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WO2024216468A1 - 隔离膜、电池单体、电池和用电装置 - Google Patents

隔离膜、电池单体、电池和用电装置 Download PDF

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Publication number
WO2024216468A1
WO2024216468A1 PCT/CN2023/088796 CN2023088796W WO2024216468A1 WO 2024216468 A1 WO2024216468 A1 WO 2024216468A1 CN 2023088796 W CN2023088796 W CN 2023088796W WO 2024216468 A1 WO2024216468 A1 WO 2024216468A1
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Prior art keywords
aldehyde
polymer
ketone polymer
battery
substituted
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PCT/CN2023/088796
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English (en)
French (fr)
Inventor
彭琳
彭爽娟
李白清
金海族
赵丰刚
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2023/088796 priority Critical patent/WO2024216468A1/zh
Publication of WO2024216468A1 publication Critical patent/WO2024216468A1/zh

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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of batteries, and in particular to an isolation membrane, a battery cell, a battery and an electrical device.
  • Battery cells have the characteristics of high capacity and long life, and are therefore widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc.
  • the embodiments of the present application are made in view of the above-mentioned problems, and an object thereof is to provide a separator, a battery cell, a battery, and an electric device.
  • the first aspect of the present application provides an isolation membrane, which includes an isolation body and a polymer layer arranged on at least one surface of the isolation body, wherein the polymer layer includes an aldehyde-ketone polymer, wherein the aldehyde-ketone polymer is made into a sheet structure; the sheet structure is subjected to a dynamic frequency scanning test at (T m +20)°C to obtain an elastic modulus G'-energy loss modulus G" curve, the slope of the elastic modulus G'-energy loss modulus G" curve is K, 0.8 ⁇ K ⁇ , and T m °C represents the melting temperature of the aldehyde-ketone polymer.
  • the entanglement state of the molecular chains can be reduced, which is beneficial to the diffusion of the electrolyte between the molecular chains; and the polymer still maintains a certain molecular chain entanglement state, which can lock the electrolyte inside the polymer, and can reduce the risk of the polymer dissolving in the electrolyte, thereby improving the stability of the polymer performance;
  • the polymer and the electrolyte can construct a three-dimensional connected interface between the isolation membrane and the electrode, and the interface has a network structure, which is beneficial to increase the rate of diffusion of active ions such as lithium ions from the electrolyte phase to the electrode, and increase the conductivity of the isolation membrane, reduce concentration polarization, and allow the active ions to be quickly embedded in the electrode and evenly deposited, thereby improving the storage performance of the battery cell.
  • 0.8 ⁇ K ⁇ 100 In some embodiments, 0.8 ⁇ K ⁇ 100; optionally, 0.8 ⁇ K ⁇ 10.
  • an aldehyde-ketone polymer is added to a first solvent at 70°C to form an aldehyde-ketone polymer system; the aldehyde-ketone polymer system is allowed to stand at 70°C for 8 hours and at 25°C for ⁇ 24 hours, and then the aldehyde-ketone polymer system is filtered through a 200-mesh filter to leave a first substance, wherein the mass of the aldehyde-ketone polymer is q, and its unit is g; the mass of the first substance is m, and its unit is g; the aldehyde-ketone polymer and the first substance satisfy: 5 ⁇ m/q ⁇ 1000.
  • the stretching of the polymer molecular chain can be achieved within the safe operating temperature range of the battery cell, promoting the mutual attraction and physical bonding between the polymer molecular chain and the electrolyte.
  • the activity of the aldehyde-ketone polymer molecular chain segments is reduced, and they remain attached to the surface of the isolation body and lock the electrolyte in the space environment where the polymer is located, forming a gel or a gel-like state, which can increase the transmission rate of active ions such as lithium ions and improve storage performance.
  • the glass transition temperature of the aldehyde-ketone polymer is Tg, which is expressed in °C, -100 ⁇ Tg ⁇ 50; optionally, -80 ⁇ Tg ⁇ 30.
  • the glass transition temperature of the polymer is relatively low, the segment flexibility of the molecular chain is better, and adjacent molecular chains are easier to open.
  • the aldehyde-ketone polymer comprises a structural unit represented by formula (I),
  • R1 includes a single bond, a substituted or unsubstituted C1-C6 methylene group
  • R2 includes a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group
  • R1 includes a single bond, a substituted or unsubstituted C1-C4 methylene group
  • R2 includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group.
  • the aldehyde-ketone polymer includes at least one of the structural units represented by formula (I-1) to the structural units represented by formula (I-6),
  • the aldehyde-ketone polymer comprises a structural unit represented by formula (II),
  • R3 to R6 each independently include a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group or a substituted or unsubstituted C1-C3 alkoxy group; r and s are each independently selected from an integer from 0 to 5, and at least one of r and s is selected from a positive integer.
  • R 3 to R 6 each independently include a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C2 hydroxyalkyl group, or a substituted or unsubstituted C1-C2 alkoxy group.
  • the aldehyde-ketone polymer includes at least one of the structural units represented by formula (II-1) to the structural units represented by formula (II-4),
  • n is selected from a positive integer ranging from 500 to 15,000.
  • the aldehyde-ketone polymer has a molecular weight of 1.2 ⁇ 10 5 g/mol to 1.0 ⁇ 10 6 g/mol.
  • the molecular chains of the aldehyde-ketone polymer can be stretched in the electrolyte, but are not easily completely dissolved and dispersed by the electrolyte, which is beneficial to regulating the uniform distribution and dispersion of the molecular chains of the aldehyde-ketone polymer in the electrolyte; and can further improve the flexibility between the molecular chains of the aldehyde-ketone polymer, and the interaction force between the molecular chains is relatively weak, which is beneficial for the solvent molecules in the electrolyte to open the molecular chains, enter between the molecular chains, and be wrapped by the molecular chains, thereby facilitating the active ions to enter the active substance through the solvent, thereby realizing the smooth and rapid migration of the active ions.
  • the isolation body includes a substrate, and the polymer layer is disposed on at least one surface of the substrate.
  • the isolation body includes a substrate and a heat-resistant coating, wherein the heat-resistant coating is disposed on at least one surface of the substrate, and the polymer layer is disposed on a surface of the heat-resistant coating facing away from the substrate.
  • the polymer layer further comprises heat-resistant particles.
  • the heat-resistant particles and the aldehyde-ketone polymer work synergistically to further improve the heat resistance and ion transmission performance of the isolation membrane as a whole.
  • the mass percent of the aldehyde-ketone polymer is based on the total mass of the polymer layer.
  • the ratio of the mass percentage of the heat-resistant particles to the mass percentage of the heat-resistant particles is (0.2 to 5): 1; optionally (0.5 to 2): 1.
  • the coating weight of the polymer layer may be 0.5 mg/1540.25 mm 2 to 5 mg/1540.25 mm 2 .
  • the coating weight of the polymer layer is within the above range, the heat resistance and ion transmission performance of the entire separator can be further improved.
  • the present application proposes a battery cell, comprising an isolation membrane as described in any embodiment of the first aspect of the present application.
  • the present application proposes a battery, comprising a battery cell as described in any embodiment of the second aspect of the present application.
  • the present application proposes an electrical device, comprising a battery as described in any embodiment of the third aspect of the present application.
  • FIG. 1 is a schematic diagram of a battery cell according to an embodiment of the present application.
  • FIG. 2 is an exploded schematic diagram of an embodiment of the battery cell of FIG. 1 .
  • FIG. 3 is a schematic diagram of an embodiment of a battery module of the present application.
  • FIG. 4 is a schematic diagram of an embodiment of a battery pack of the present application.
  • FIG. 5 is an exploded schematic diagram of the embodiment of the battery pack shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of an embodiment of an electric device including the battery cell of the present application as a power source.
  • “Scope” disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • a method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • alkyl encompasses both straight and branched chain alkyls.
  • the alkyl can be a C1-C5 alkyl, a C1-C4 alkyl, a C1-C3 alkyl, a C1-C2 alkyl.
  • the alkyl includes a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, etc.
  • the alkyl can be optionally substituted. When substituted, the substituent includes a fluorine atom.
  • alkoxy refers to a group in which an alkyl group is connected to an oxygen atom by a single bond.
  • the alkoxy group can be a C 1 to C 5 alkoxy group, a C 1 to C 3 alkoxy group, a C 1 to C 2 alkoxy group.
  • the alkoxy group can include a methoxy group, an ethoxy group, a propoxy group.
  • the alkoxy group can be optionally substituted.
  • halogen atom means a fluorine atom, a chlorine atom, a bromine atom or the like.
  • hydrogen refers to 1H (protium, H), 2H (deuterium, D) or 3H (tritium, T). In various embodiments, “hydrogen” may be 1H (protium, H).
  • a battery cell includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte.
  • the separator is located between the positive electrode sheet and the negative electrode sheet to isolate the positive electrode sheet from the negative electrode sheet.
  • the positive electrode sheet as an example, there is a solid-liquid contact interface between the positive active material contained in the positive electrode sheet and the electrolyte.
  • the positive active material may have a side reaction with the electrolyte, which deteriorates the storage performance of the battery cell, and the side reaction may produce products that are not conducive to the cycle of the battery cell, thereby deteriorating the storage performance of the battery cell.
  • the embodiment of the present application proposes an isolation membrane from the perspective of constructing an interface.
  • the isolation membrane includes an isolation body and a polymer layer arranged on at least one surface of the isolation body.
  • the polymer molecular chains in the polymer layer have segment flexibility.
  • the isolation membrane is applied to a battery cell, the polymer layer is in contact with the electrolyte, the polymer molecular chains stretch and open, and the electrolyte can diffuse between the molecular chains, thereby constructing a three-dimensional connected interface between the isolation membrane and the electrode.
  • the interface has a network structure, which is beneficial to increase the rate of diffusion of active ions such as lithium ions from the electrolyte phase to the electrode, and to increase the conductivity of the isolation membrane, reduce concentration polarization, and enable active ions to be quickly embedded in the electrode and evenly deposited, thereby improving the storage performance of the battery cell.
  • an embodiment of the present application proposes an isolation membrane, which includes an isolation body and a polymer layer arranged on at least one surface of the isolation body, wherein the polymer layer includes an aldehyde-ketone polymer, wherein the aldehyde-ketone polymer is made into a sheet structure; the sheet structure is subjected to a dynamic frequency scanning test at (T m +20)°C to obtain an elastic modulus G'-energy loss modulus G" curve, the slope of the elastic modulus G'-energy loss modulus G" curve is K, 0.8 ⁇ K ⁇ , and T m °C represents the melting temperature of the aldehyde-ketone polymer.
  • the preparation process of the sheet structure is as follows: the polymer is vacuum dried at 80°C for 12h.
  • the dried polymer is hot-pressed into a thin sheet by a flat vulcanizer, the hot pressing temperature is set to (Tm+20)°C, the calendering thickness is 1-2min, the calendering time is 2min, and the pressure is 8MPa.
  • the sample is taken out and placed on another vulcanizer of the same model for cold pressing, and the cold pressing pressure is 10MPa.
  • a fixed 10-size polymer disc (sheet structure) can be obtained using a circular mold with a diameter of 25mm.
  • the sheet structure can be a disc with a thickness of 1-2mm and a diameter of 25mm; it can also be prepared according to the sample standard required by the test equipment.
  • the elastic modulus G’-dissipation modulus G” in the terminal region of the elastic modulus G’-dissipation modulus G” curve conforms to the frequency dependence, and the longest chain of the polymer plays a role in the viscoelastic behavior.
  • the specific steps of the dynamic frequency sweep test are as follows: The dynamic frequency sweep test is performed using a TA-AR2000EX rotational rheometer (TAinstruments, USA), with a parallel plate diameter of 25 mm and a thickness of 0.9 mm. To ensure that the test is in the linear point-elastic region, the strain during the dynamic frequency sweep test is 2%, the test temperature is Tm+20°C, and the frequency sweep range of the test is: 500rad/s ⁇ w 2 ⁇ 0.05rad/s, so as to obtain data in the low frequency region as much as possible.
  • the dynamic frequency scanning test can characterize the degree of entanglement of molecular chains under solid phase melting (melt state). Compared with linear structures or short branched structures, long branched structures, network structures and low cross-linked structures have a high degree of entanglement, which will show deviation from linear terminal behavior, and the polymer will show solid phase behavior.
  • the entanglement state of the molecular chain can be further reduced, which is conducive to the diffusion of the electrolyte between the molecular chains; and the polymer still maintains a certain molecular chain entanglement state, which can lock the electrolyte inside the polymer and reduce the polymer
  • the polymer and the electrolyte can construct a three-dimensional connected interface between the isolation membrane and the electrode, and the interface has a network structure, which is beneficial to increase the diffusion rate of active ions such as lithium ions from the electrolyte phase to the electrode, and increase the conductivity of the isolation membrane, reduce concentration polarization, and allow the active ions to be quickly embedded in the electrode and evenly deposited, thereby improving the storage performance of the battery cell.
  • 0.8 ⁇ K ⁇ 100 In some embodiments, 0.8 ⁇ K ⁇ 100; optionally, 0.8 ⁇ K ⁇ 10.
  • K may be 0.8, 1, 1.01, 1.1, 1.2, 1.5, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range consisting of any two of the above values.
  • the glass transition temperature of the aldehyde-ketone polymer is Tg, with the unit of °C, -100 ⁇ Tg ⁇ 50; optionally, -80 ⁇ Tg ⁇ 30.
  • the glass transition temperature is the transition temperature of the polymer chain segments from freezing to movement.
  • the glass transition temperature has a certain influence on the flexibility of the polymer molecular chain. The lower the glass transition temperature, the better the flexibility of the polymer molecular chain at room temperature. The higher the glass transition temperature, the worse the flexibility of the molecular chain at room temperature.
  • the glass transition temperature can be measured by differential scanning calorimetry DSC. Specifically, the test steps are: take 0.5g to 0.8g of sample, place the sample in a carrier crucible, and perform temperature rise and fall treatment on the sample under a nitrogen atmosphere.
  • the temperature is raised from an initial temperature 20°C lower than the intrinsic Tg of the material to a cutoff temperature 20°C higher than the intrinsic Tm of the material at a heating rate of 10°C/min.
  • the actual glass transition temperature Tg and melting temperature Tm of the material are determined according to the endothermic and exothermic peak or transition point of the material in the process.
  • the glass transition temperature of the polymer is relatively low, the segment flexibility of the molecular chain is better, and the adjacent molecular chains are easier to open.
  • the glass transition temperature of the aldehyde-ketone polymer can be -100°C, -90°C, -80°C, -60°C, -30°C, 0°C, 30°C, 50°C, or a range consisting of any two of the above values.
  • the aldehyde-ketone polymer comprises a structural unit represented by formula (I),
  • R1 includes a single bond, a substituted or unsubstituted C1-C6 methylene group
  • R2 includes a hydrogen atom, a substituted or unsubstituted C1-C6 alkyl group
  • R1 includes a single bond, a substituted or unsubstituted C1-C4 methylene group.
  • R1 includes a single bond, a substituted or unsubstituted C1-C2 methylene group.
  • R 2 includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group.
  • a single bond indicates that the group does not exist, and the atoms on both sides of the group are connected by a single bond.
  • R1 is a single bond, which indicates that the carbon atoms on both sides of R1 are connected by a single bond.
  • the aldehyde-ketone polymer includes at least one of the structural units represented by formula (I-1) to the structural units represented by formula (I-6),
  • the aldehyde-ketone polymer comprises a structural unit represented by formula (II),
  • R3 to R6 each independently include a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group or a substituted or unsubstituted C1-C3 alkoxy group; r and s are each independently selected from an integer from 0 to 5, and at least one of r and s is selected from a positive integer.
  • R 3 to R 6 each independently include a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C2 hydroxyalkyl group, or a substituted or unsubstituted C1-C2 alkoxy group.
  • the aldehyde-ketone polymer includes at least one of the structural units represented by formula (II-1) to the structural units represented by formula (II-4),
  • the molecular chain entanglement degree of the above-mentioned aldehyde-ketone polymer is low, which is conducive to improving the flexibility of the molecular chain.
  • the molecular chain can fully stretch in the electrolyte, thereby further improving the interface performance.
  • the above-mentioned polymers are only examples of the structural groups of the main molecular chains.
  • the polymers can also be obtained by copolymerizing the above-mentioned structural groups with a small amount of other types of structural groups (such as olefin structural units, ester monomers, nitrile monomers, amide monomers and other structural units).
  • the groups of the polymers of the present application can be detected by infrared spectrophotometry IR. Specifically, the polymers are tested by Thermo Nicolet Nexus 670 attenuated total reflection Fourier transform infrared spectrometer (FTIR-ATR), and then tested with reference to standard GB/T6040-2002.
  • the test range is: ATR method 600-4000 cm -1 ; repeatability: ⁇ 2 cm -1 ; resolution: better than 4 cm -1 ; transmission depth 0.2-0.6 ⁇ m.
  • the structure of the polymer of the present application can be tested by nuclear magnetic resonance NMR. Specifically, 1H NMR and 13C NMR are carried out on a Varian Mercury Plus-400 nuclear magnetic resonance instrument. The test temperature is 20° C., TMS is used as the internal standard, CDCl 3 is used as the solvent, and the proton resonance frequency is 400 MHz.
  • the polymer monomer type of the present application (especially suitable for monomers with a small proportion in the polymer) can be tested by pyrolysis-gas chromatography-mass spectrometry, and the specific test steps are as follows: accurately weigh 0.5 mg of sample and put it into the sample cup, fix it to the injection rod, and then put it into the pyrolyzer installed near the GC (gas chromatography) injection port. After the temperature of the pyrolyzer reaches the set temperature, press the injection button, and the sample cup quickly falls into the core of the pyrolysis furnace by free fall. In the inert gas N2 atmosphere, the volatile components are instantly vaporized and carried into the gas chromatography column by the carrier gas for separation. Finally, it is detected by a flame ionization detector FID or a mass spectrometer MS to obtain a gas chromatogram or a total ion flow diagram.
  • FID flame ionization detector
  • MS mass spectrometer MS
  • the substituents may include one or more of nitrile group (-CN), nitro group, sulfonic acid group, sulfonyl group, carboxyl group, amide group, carboxyl group, ester group, halogen atom such as chlorine atom, fluorine atom, bromine atom.
  • -CN nitrile group
  • sulfonic acid group sulfonyl group
  • carboxyl group amide group
  • carboxyl group ester group
  • halogen atom such as chlorine atom, fluorine atom, bromine atom.
  • n is selected from a positive integer ranging from 500 to 15,000.
  • n is selected from a positive integer ranging from 500 to 10,000.
  • the molecular weight of the polymer is 1.2 ⁇ 10 5 g/mol to 1.0 ⁇ 10 6 g/mol.
  • the molecular chain of the aldehyde-ketone polymer can be stretched in the electrolyte, but it is not easy to be completely dissolved and dispersed by the electrolyte, which is conducive to regulating the uniform distribution and dispersion of the aldehyde-ketone polymer molecular chain in the electrolyte; and the flexibility between the molecular chains of the aldehyde-ketone polymer can be further improved, and the force between the molecular chains is relatively weak, which is conducive to the solvent molecules in the electrolyte to open the molecular chains and enter between the molecular chains, and be wrapped by the molecular chains, thereby facilitating the active ions to enter the active substance through the solvent, and realizing the smooth and rapid migration of the active ions.
  • the molecular weight of the aldehyde-ketone polymer can be 1.2 ⁇ 10 5 g/mol, 2 ⁇ 10 5 g/mol, 5 ⁇ 10 5 g/mol, 8 ⁇ 10 5 g/mol, 1 ⁇ 10 6 g/mol, or a range consisting of any two of the above values.
  • the molecular weight of the polymer is well known in the art and can be measured using commonly used equipment and methods in the art.
  • the Gel Permeation Chromatography (GPC) test can be used. The specific test steps are as follows: take an appropriate amount of the sample to be tested (the sample concentration is sufficient to ensure 8%-12% shading), add 20 ml of deionized water, and simultaneously conduct an external ultraviolet for 5 minutes (53KHz/120W). Ensure that the sample is completely dispersed, and then measure the sample according to GB/T19077-2016/ISO13320:2009 standard.
  • a multi-angle laser light scattering instrument MALLS is used for testing, specifically, a GPC combined with a Dawn Heleos II multi-angle laser light scattering device, an Optilab T-rEX refractive index (RI) detector and a ViscoStar II viscometer (Wyatt Technology Corporation, USA) is used. The test is carried out at 30°, tetrahydrofuran is used as the mobile phase, and the flow rate is 1.0 ml/min.
  • the commercial software ASTRA6 is used to process the SEC-SAMLL data to obtain the molecular weight parameters.
  • the cycle performance and storage performance of the battery cell can be further improved.
  • an aldehyde-ketone polymer is added to a first solvent at 70°C to form an aldehyde-ketone polymer system; the aldehyde-ketone polymer system is left at 70°C for 8 hours, and at 25°C for ⁇ 24 hours. After two stages of standing treatment, the aldehyde-ketone polymer system is partially swollen and adsorbed to form a gel-state substance, and then the aldehyde-ketone polymer system is filtered through a 200-mesh filter to leave the first substance.
  • the mass of the aldehyde-ketone polymer is q, and its unit is g; the mass of the first substance is m, and its unit is g; the aldehyde-ketone polymer and the first substance satisfy: 5 ⁇ m/q ⁇ 1000; optionally, 10 ⁇ m/q ⁇ 1000; further optionally, 10 ⁇ m/q ⁇ 50.
  • m/q can be 5, 10, 20, 25, 28, 30, 32, 35, 40, 50, 80, 100, 200, 500, 1000 or a range consisting of any two of the above values.
  • the ratio of the mass content of the polymer to the mass content of the first solvent ranges from 1:100 to 1:10, such as 3:50.
  • the first solvent is the same as or similar to the solvent of the electrolyte, and the first solvent may include at least one of a carbonate solvent and an ether solvent.
  • the carbonate solvent includes a cyclic carbonate solvent and/or a linear carbonate solvent.
  • the cyclic carbonate solvent includes one or more of ethylene carbonate EC, vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinyl vinyl carbonate VEC, and dioctyl carbonate CC.
  • the linear carbonate solvent includes one or more of dimethyl carbonate DMC, diethyl carbonate DEC, ethyl methyl carbonate EMC, diphenyl carbonate DPC, methyl allyl carbonate MAC, and polycarbonate VA.
  • the ether solvent includes one or more of tetrahydrofuran THF, 2-methyltetrahydrofuran 2me-thf, 1,3-dioxolane DOL, dimethoxymethane DMM, 1,2-dimethoxyethane DME, and diglyme DG.
  • the first solvent may also contain a lithium salt and an electrolyte additive, such as lithium hexafluorophosphate, vinylene carbonate VC, fluorovinylene carbonate FEC, and the like.
  • a lithium salt such as lithium hexafluorophosphate, vinylene carbonate VC, fluorovinylene carbonate FEC, and the like.
  • m/q is also referred to as precipitation value, which characterizes the ability of the polymer and the electrolyte to transform into a gel-state substance.
  • the first substance mainly includes a gel-state substance formed by a polymer and a first solvent.
  • the molecular structure of the polymer will not change substantially.
  • the first material is dried at 80° C. for 12 h to remove the first
  • the solvent is detected by infrared spectrophotometry IR or nuclear magnetic resonance NMR test, and the main component of the first substance after drying is the polymer mentioned above.
  • the embodiments of the present application can achieve the stretching of polymer molecular chains within the safe operating temperature range of the battery monomer by increasing the temperature, promoting the mutual attraction and physical combination of the polymer molecular chains and the electrolyte.
  • the activity of the aldehyde-ketone polymer molecular chain segments is reduced, and they remain attached to the surface of the isolation body and lock the electrolyte in the spatial environment where the polymer is located, forming a gel or a gel-like state, which can increase the transmission rate of active ions such as lithium ions, and improve the cycle performance and storage performance.
  • the isolation membrane includes an isolation body and a polymer layer, and the polymer layer is disposed on at least one surface of the isolation body, which means that the polymer layer can be disposed on one of the surfaces of the isolation body or on both surfaces of the isolation body. Since the isolation body has a variety of structural forms, the polymer layer has a variety of settings accordingly. Aldehyde-ketone polymers can be dispersed in a solvent to form a polymer mixed system, and the polymer mixed system is coated on the isolation body by a coating process such as atomization spraying and gravure coating.
  • the isolation body includes a substrate, and the polymer layer is disposed on at least one surface of the substrate.
  • the isolation body includes a substrate and a heat-resistant coating
  • the heat-resistant coating is disposed on at least one surface of the substrate
  • the polymer layer is disposed on the surface of the heat-resistant coating facing away from the substrate. It is understood that the heat-resistant coating can be disposed on one surface of the substrate, or on both surfaces of the substrate.
  • the substrate may include at least one of a porous polyolefin-based resin film (e.g., at least one of polyethylene, polypropylene, and polyvinylidene fluoride), a porous glass fiber, and a porous non-woven fabric.
  • the substrate may be a single-layer film or a multi-layer composite film. When the substrate is a multi-layer composite film, the materials of each layer may be the same or different.
  • the porosity of the substrate is greater than or equal to 25%, and can be 25% to 50%.
  • the air permeability of the substrate can be improved, which is beneficial to the migration of active ions, and because the porosity is relatively small, the mechanical properties of the substrate can be improved, and it can provide good support for the polymer layer.
  • the thickness of the substrate may be less than or equal to 16 ⁇ m, and may be 5 ⁇ m to 12 ⁇ m.
  • the thickness of the substrate may be 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, 16 ⁇ m, or a range consisting of any two of the above values.
  • the heat-resistant coating may include heat-resistant particles.
  • the heat-resistant particles include at least one of inorganic particles and organic particles. By adding heat-resistant particles, the heat resistance of the isolation film can be improved.
  • the mass percentage of the inorganic particles in the heat-resistant coating is ⁇ 30.
  • the mass percentage of the inorganic particles in the heat-resistant coating is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30% or a range consisting of any two of the above values.
  • the inorganic particles may include at least one of inorganic particles having a dielectric constant of 5 or more, inorganic particles having the ability to transport active ions, and inorganic particles capable of electrochemical oxidation and reduction.
  • the inorganic particles having a dielectric constant of 5 or more may include boehmite ( ⁇ -AlOOH), aluminum oxide (Al 2 O 3 ), barium sulfate (BaSO 4 ), magnesium oxide (MgO), magnesium hydroxide (Mg(OH) 2 ), silicon oxide SiO x (0 ⁇ x ⁇ 2), tin dioxide (SnO 2 ), titanium oxide (TiO 2 ), At least one of calcium (CaO), zinc oxide (ZnO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), nickel oxide (NiO), hafnium oxide (HfO 2 ), cerium oxide (CeO 2 ), zirconium titanate (ZrTiO 3 ), barium titanate (BaTiO 3 ), magnesium fluoride (MgF 2 ), Pb(Zr,Ti)O 3 (abbreviated as PZT), Pb 1-m Lam Zr 1-n Tin O 3 (
  • the inorganic particles capable of transporting active ions may include lithium phosphate ( Li3PO4 ), lithium titanium phosphate ( LixTiy ( PO4 ) 3 , 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 3), lithium aluminum titanium phosphate ( LixAlyTiz ( PO4 ) 3 , 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 3), (LiAlTiP) xOy type glass (0 ⁇ x ⁇ 4, 0 ⁇ y ⁇ 13), lithium lanthanum titanate (LixLayTiO3, 0 ⁇ x ⁇ 2 , 0 ⁇ y ⁇ 3 ), lithium germanium thiophosphate (LixGeyPzSw, 0 ⁇ x ⁇ 4, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, 0 ⁇ w ⁇ 5) , lithium nitride (LixNy , 0 ⁇ x ⁇ 4, 0 ⁇ y ⁇ 2), SiS2 type glass ( LixSiySz
  • the inorganic particles capable of electrochemical oxidation and reduction may include at least one of lithium-containing transition metal oxides, olivine-structured lithium-containing phosphates, carbon-based materials, silicon-based materials, tin-based materials, and lithium-titanium compounds.
  • the heat-resistant coating may also include other organic particles, for example, the organic particles may include at least one of polystyrene, polyethylene, polyimide, melamine resin, phenolic resin, polypropylene, polyester (such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyphenylene sulfide, polyaramid, polyamideimide, polyimide, copolymer of butyl acrylate and ethyl methacrylate and mixtures thereof.
  • the organic particles may include at least one of polystyrene, polyethylene, polyimide, melamine resin, phenolic resin, polypropylene, polyester (such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyphenylene sulfide, polyaramid, polyamideimide, polyimide, copolymer of butyl acrylate and ethyl methacrylate and mixtures thereof.
  • the heat-resistant coating may further include a binder.
  • the binder may include at least one of an aqueous solution type acrylic resin (e.g., acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer or copolymer with other comonomers), polyvinyl alcohol (PVA), isobutylene-maleic anhydride copolymer, and polyacrylamide.
  • an aqueous solution type acrylic resin e.g., acrylic acid, methacrylic acid, sodium acrylate monomer homopolymer or copolymer with other comonomers
  • PVA polyvinyl alcohol
  • isobutylene-maleic anhydride copolymer e.g., isobutylene-maleic anhydride copolymer, and polyacrylamide.
  • the thickness of the heat-resistant coating may be ⁇ 4 ⁇ m. This helps to improve the energy density of the battery cell.
  • the thickness of the heat-resistant coating refers to the thickness of the heat-resistant coating located on one side of the substrate. Exemplarily, the thickness of the heat-resistant coating may be 0.1 ⁇ m, 0.5 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, or a range consisting of any two of the above values.
  • the polymer layer may further include heat-resistant particles, and the heat-resistant particles and the aldehyde-ketone polymer may work synergistically to further improve the heat resistance and ion transmission performance of the isolation membrane as a whole.
  • the aldehyde-ketone polymer and the heat-resistant particles may be dispersed in a solvent to form a polymer mixed system, and the polymer mixed system may be coated on the isolation body by a coating process such as atomization spraying and gravure coating.
  • the ratio of the mass percentage of the aldehyde-ketone polymer to the mass percentage of the heat-resistant particles is (0.2 to 5.0):1; optionally (0.5 to 2.0):1.
  • the contents of heat-resistant particles and aldehyde-ketone polymers are within the above range, the heat resistance and ion transmission properties of the isolation membrane as a whole can be further improved.
  • the ratio of the mass percentage of the aldehyde-ketone polymer to the mass percentage of the heat-resistant particles can be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.8:1, 1.0:1, 1.2:1, 1.5:1, 1.8:1, 2.0:1, 2.5:1, 2.8:1, 3.0:1, 3.2:1, 3.5:1, 3.8: 1, 4.0:1, 4.2:1, 4.5:1, 4.8:1, 5.0:1 or a range consisting of any two of the above values.
  • the coating weight of the polymer layer may be 0.5 mg/1540.25 mm 2 to 5 mg/1540.25 mm 2 .
  • the coating weight of the polymer layer is within the above range, the heat resistance and ion transmission performance of the entire separator can be further improved.
  • the coating weight of the polymer layer may be 0.5 mg/1540.25 mm 2 to 3.5 mg/1540.25 mm 2 .
  • the coating weight of the polymer layer may be 0.5 mg/1540.25 mm 2 , 0.6 mg/1540.25 mm 2 , 0.8 mg/1540.25 mm 2 , 1.0 mg/1540.25 mm 2 , 1.2 mg/1540.25 mm 2 , 1.5 mg/1540.25 mm 2 , 1.8 mg/1540.25 mm 2 , 2.0 mg/1540.25 mm 2 , 2.5 mg/1540.25 mm 2 , 3 mg/1540.25 mm 2 , 3.5 mg/1540.25 mm 2 , 4 mg/1540.25 mm 2 , 4.5 mg/1540.25 mm 2 , 5 mg/1540.25 mm 2 2 or a range consisting of any two of the above values.
  • the coating weight of the polymer layer refers to the single-sided weight.
  • the polymer layer is provided on both sides of the substrate, it refers to the coating weight of the polymer layer on one side of the substrate.
  • the coating weight is well known in the art and can be detected by using equipment and methods well known in the art.
  • the coating weight of the polymer in the isolation film can be obtained by cutting the same mother roll substrate and isolation film into small discs of 1540.25 mm2 , weighing 10 small discs of isolation film respectively, and calculating the coating weight of the polymer in the isolation film.
  • an embodiment of the present application proposes a battery cell, wherein the battery cell includes an electrode assembly and an electrolyte, wherein the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the separator includes a separator as in any embodiment of the first aspect of the present application.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be a positive electrode active material for a battery cell known in the art.
  • the positive electrode active material can include at least one of the following materials: a lithium-containing phosphate compound, a lithium-containing transition metal oxide, a sodium-containing phosphate compound, and a sodium-containing transition metal oxide.
  • the general formula of the olivine-type phosphate active material is: Li x A y Me a M b P 1-c X c Y z , wherein 0 ⁇ x ⁇ 1.3, 0 ⁇ y ⁇ 1.3, and 0.9 ⁇ x+y ⁇ 1.3; 0.9 ⁇ a ⁇ 1.5, 0 ⁇ b ⁇ 0.5, and 0.9 ⁇ a+b ⁇ 1.5; 0 ⁇ c ⁇ 0.5; 3 ⁇ z ⁇ 5;
  • A includes one or more of Na, K, and Mg;
  • Me includes one or more of Mn, Fe, Co, and Ni;
  • M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce;
  • X includes one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F.
  • lithium transition metal oxides layered materials such as ternary, lithium/sodium nickel oxide, lithium/sodium cobalt oxide
  • the general formula of the layered positive electrode active material is: Li x A y Ni a Co b Mn c M (1-abc) Y z , wherein 0 ⁇ x ⁇ 2.1, 0 ⁇ y ⁇ 2.1, and 0.9 ⁇ x+y ⁇ 2.1; 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1, and 0.1 ⁇ a+b+c ⁇ 1; 1.8 ⁇ z ⁇ 3.5;
  • A includes one or more of Na, K, and Mg;
  • M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce;
  • Y includes one or more of O and F.
  • the layered structure positive electrode active material may include one or more of lithium cobalt oxide LCO, lithium nickel oxide LNO, lithium manganese oxide LMO, LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) and NCA.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • a metal foil an aluminum foil or an aluminum alloy foil may be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include a combination of one or more selected from aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy
  • the polymer material base layer may include a combination of one or more selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).
  • the positive electrode active material layer may further include a positive electrode conductive agent.
  • a positive electrode conductive agent includes a combination of one or more selected from superconducting carbon, conductive carbon black, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the mass percentage of the positive electrode conductive agent is less than 5%.
  • the positive electrode active material layer may also optionally include a positive electrode binder.
  • the positive electrode binder may include a combination of one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the mass percentage of the positive electrode binder is less than 5%. Compared with the crystallinity of the aldehyde-ketone polymer of the embodiment of the present application, the crystallinity of the positive electrode binder is higher. Compared with the melting temperature of the aldehyde-ketone polymer of the embodiment of the present application, the melting temperature of the positive electrode binder is higher.
  • the positive electrode active material layer is usually formed by coating the positive electrode slurry on the positive electrode current collector, drying and cold pressing.
  • the positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder and any other components in a solvent and stirring them evenly.
  • the solvent can be N-methylpyrrolidone (NMP), but is not limited to this.
  • NMP N-methylpyrrolidone
  • the preparation of the positive electrode sheet is not limited to the above method, and the preparation method described above can also be used.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode active material may be a negative electrode active material for a battery cell known in the art.
  • the negative electrode active material may include but is not limited to at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate.
  • the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material.
  • the tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.
  • the negative electrode active material layer may further include a negative electrode conductive agent.
  • a negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the mass percentage of the negative electrode conductive agent is ⁇ 5%.
  • the negative electrode active material layer may further include a negative electrode binder.
  • the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • SR-1B water-soluble unsaturated resin
  • acrylic resin e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • CMCS carboxymethyl chitosan
  • the negative electrode active material layer may further include other additives.
  • other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.
  • CMC sodium carboxymethyl cellulose
  • PTC thermistor materials etc.
  • the mass percentage of the other additives is ⁇ 2%.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • a metal foil a copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy.
  • the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).
  • the negative electrode active material layer is usually formed by coating the negative electrode slurry on the negative electrode current collector, drying and cold pressing.
  • the negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional auxiliary agents in a solvent and stirring them evenly.
  • the solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.
  • NMP N-methylpyrrolidone
  • the preparation of the negative electrode sheet is not limited to the above method, and the preparation method described above can also be used.
  • the negative electrode plate does not exclude other additional functional layers in addition to the negative electrode active material layer.
  • the negative electrode plate described in the present application also includes a conductive primer layer (for example, composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode active material layer and disposed on the surface of the negative electrode current collector.
  • the negative electrode plate described in the present application also includes a protective layer covering the surface of the negative electrode active material layer.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.
  • the electrolyte salt may include but is not limited to at least one of lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorobisoxalatophosphate (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium
  • the electrolyte salt may include but is not limited to at least one of sodium hexafluorophosphate (NaPF 6 ), sodium tetrafluoroborate (NaBF 4 ), sodium perchlorate (NaClO 4 ), sodium hexafluoroarsenate (NaAsF 6 ), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalatoborate (NaDFOB), sodium dioxalatoborate (NaBOB), sodium difluorophosphate (NaPO 2 F 2 ), sodium difluorobis(oxalatophosphate) (NaDFOP) and sodium tetrafluorooxalatophosphate (NaPF 6 ), sodium tetrafluoroxalatophosphate
  • the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), diethyl sul
  • the electrolyte may further include additives, for example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, or additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature power performance, etc.
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, or additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature power performance, etc.
  • the positive electrode sheet, the separator, and the negative electrode sheet may be formed into an electrode assembly by a winding process and/or a lamination process.
  • the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the battery cell may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, such as polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS). At least one of .
  • the positive electrode sheet, the separator, and the negative electrode sheet may be formed into an electrode assembly by a winding process or a lamination process.
  • FIG1 is a battery cell 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film may form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the battery cell 5 may be one or more, which can be adjusted according to demand.
  • the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form a battery cell.
  • the positive electrode sheet, the separator and the negative electrode sheet can be formed into an electrode assembly through a winding process or a lamination process, and the electrode assembly is placed in an outer package, and the electrolyte is injected after drying, and the battery cell is obtained through vacuum packaging, standing, forming, shaping and other processes.
  • the battery cells according to the present application can be assembled into a battery module.
  • the battery module can contain multiple battery cells, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG3 is a schematic diagram of an exemplary battery module 4.
  • a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.
  • the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.
  • Both the battery module 4 and the battery pack can be used as specific examples of batteries in the embodiments of the present application.
  • FIG4 and FIG5 are schematic diagrams of a battery pack 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, wherein the upper box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 may be arranged in the battery box in any manner.
  • the present application provides an electrical device, which includes at least one of the battery cells, battery modules and battery packs of the present application.
  • the battery cells, battery modules and battery packs can be used as power sources for electrical devices, or as energy storage units for electrical devices.
  • the electrical device can be, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the electrical device can select a battery cell, a battery module or a battery pack according to its usage requirements.
  • the power-consuming device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack 1 or a battery module can be used.
  • the power-consuming device can be a mobile phone, a tablet computer, a laptop computer, etc.
  • the power-consuming device is usually required to be light and thin, and a battery cell can be used as a power source.
  • Aluminum foil with a thickness of 12 ⁇ m was used as the positive electrode current collector.
  • the positive electrode active material LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an appropriate amount of N-methylpyrrolidone (NMP) to form a positive electrode slurry.
  • NMP N-methylpyrrolidone
  • the mass ratio of NCM622, conductive carbon black, and PVDF in the positive electrode slurry is 97.5:1.4:1.1.
  • the positive electrode slurry is coated on the current collector aluminum foil and vacuum dried at 100°C and then cold pressed. Then, after trimming, cutting, and striping, it is dried under vacuum conditions at 85°C for 4 hours to form a positive electrode sheet.
  • a copper foil with a thickness of 8 ⁇ m was used as the negative electrode current collector.
  • the negative electrode active material artificial graphite, conductive agent carbon black, adhesive styrene butadiene rubber (SBR), and thickener sodium hydroxymethyl cellulose (CMC) were mixed evenly in a weight ratio of 97.4:2:0.5:2.6 and added into deionized water to prepare the negative electrode slurry.
  • the negative electrode slurry was coated on the current collector copper foil and dried at 85°C, then cold pressed, trimmed, cut into pieces, and striped, and then dried at 120°C under vacuum conditions for 12 hours to prepare the negative electrode sheet.
  • non-aqueous organic solvents ethylene carbonate EC and ethyl methyl carbonate (EMC) are mixed in a volume ratio of 3:7 to obtain an electrolyte solvent, and then lithium salt LiPF 6 and the mixed solvent are mixed to prepare an electrolyte with a lithium salt concentration of 1 mol/L.
  • PE polyethylene film
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then they are wound to obtain an electrode assembly; the electrode assembly is placed in an outer packaging shell, and after drying, the electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, a lithium-ion battery is obtained.
  • a lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 was that the isolation film in Comparative Example 1 was a polyethylene film (PE) with a thickness of 7 ⁇ m.
  • PE polyethylene film
  • a lithium-ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 was that the material of the aldehyde-ketone polymer of the isolation membrane in Comparative Example 2 was changed.
  • a lithium-ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 was that the material of the aldehyde-ketone polymer of the isolation membrane of Example 2-1 was changed.
  • a lithium-ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 was that the thickness of the polymer layer of the isolation membrane was adjusted in Examples 3-1 to 3-5.
  • Example 4-1 adjusts the setting position of the polymer layer of the isolation membrane. Specifically, the steps of preparing the isolation membrane include:
  • PE polyethylene film
  • the silicon oxide particles and the binder aqueous solution type polyacrylic acid were uniformly mixed in a proper amount of solvent deionized water at a mass ratio of 20:80 to obtain a coating slurry.
  • the prepared coating slurry was applied on both surfaces of the PE substrate using a coater to form a heat-resistant coating.
  • a lithium-ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the composition of the polymer layer of the isolation membrane was adjusted in Examples 4-2 to 4-6. Specifically, the steps of preparing the isolation membrane included:
  • PE polyethylene film
  • the mass ratio of silicon oxide particles and aldehyde-ketone polymer in Example 4-2 is 1.5:1; the mass ratio of silicon oxide particles and aldehyde-ketone polymer in Example 4-3 is 0.5:1; the mass ratio of silicon oxide particles and aldehyde-ketone polymer in Example 4-4 is 2:1; the mass ratio of silicon oxide particles and aldehyde-ketone polymer in Example 4-5 is 0.2:1; the mass ratio of silicon oxide particles and aldehyde-ketone polymer in Example 4-5 is 0.5:1.
  • the lithium-ion batteries prepared in the examples and comparative examples were charged to 4.25V at a constant current of 1/3C at room temperature, then charged to a current of 0.05C at a constant voltage of 4.25V, left for 5 minutes, and then discharged to 2.8V at 1/3C.
  • the resulting capacity was recorded as the initial capacity C0.
  • the battery capacity retention rate data in the table is the data measured after 150 days of storage under the above test conditions, that is, the value of P5.
  • the lithium-ion battery prepared in the embodiment and comparative example is charged to 4.25V at 1/3C constant current at 25°C, and then charged to 0.05C at 4.25V constant voltage. After 5 minutes, the voltage V1 is recorded. Then, it is discharged at 1/3C for 30s, and the voltage V2 is recorded. Then (V2-V1)/1/3C is used to obtain the internal resistance DCR1 of the battery after the first cycle.
  • the battery is charged to 4.25V at 1/3C constant current at room temperature, and then charged to 0.05C at 4.25V constant voltage. After 5 minutes, it is discharged to 2.8V at 1/3C. The obtained capacity is recorded as the initial capacity C0. Then, it is adjusted to 97% SOC and transferred to 60°C environment for storage.
  • the battery internal resistance increase ratio in the table (DCRn-DCR1)/DCR1*100%.
  • the data in the table are measured after storage for 150D under the above test conditions.
  • 70% formaldehyde means that the molar percentage of formaldehyde is 70% based on the total molar amount of formaldehyde and polyvinyl alcohol.
  • the aldehyde-ketone polymer of the present application is added to the isolation membrane in the embodiment of the present application, and the cycle performance and storage performance of the lithium-ion battery are improved.
  • Comparative Example 2 when the embodiment of the present application satisfies 0.8 ⁇ K ⁇ , especially 0.8 ⁇ K ⁇ 100; optionally, when 0.8 ⁇ K ⁇ 10, its molecular chain arrangement tends to be loose, the force between the molecular chains is small, the adjacent molecular chains are easily opened, and the chain segment movement is achieved through the internal rotation between the molecules, forming a molecular chain structure with high flexibility, which can more significantly improve the cycle performance and storage performance of the lithium-ion battery.

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Abstract

本申请提供了一种隔离膜、电池单体、电池和用电装置，所述隔离膜包括隔离本体和设置于所述隔离本体至少一个表面上的聚合物层，所述聚合物层包括醛酮聚合物，其中，将所述醛酮聚合物制成片状结构体；所述片状结构体在(Tm+20)℃下经动态频率扫描测试获得弹性模量G'-耗能模量G"曲线，所述弹性模量G'-耗能模量G"曲线的斜率为K，0.8≤K＜∞，Tm℃表示所述醛酮聚合物的熔融温度。

Description

隔离膜、电池单体、电池和用电装置 技术领域
本申请涉及电池领域，具体涉及一种隔离膜、电池单体、电池和用电装置。
背景技术
电池单体具有容量高、寿命长等特性，因此广泛应用于电子设备，例如手机、笔记本电脑、电瓶车、电动汽车、电动飞机、电动轮船、电动玩具汽车、电动玩具轮船、电动玩具飞机和电动工具等等。
随着电池应用范围越来越广泛，对电池单体性能的要求也逐渐严苛。然而，目前电池单体的存储性能较差，仍需要进一步提高。
发明内容
本申请实施方式是鉴于上述课题而进行的，其目的在于，提供一种隔离膜、电池单体、电池和用电装置。
本申请的第一方面提供了一种隔离膜，所述隔离膜包括隔离本体和设置于所述隔离本体至少一个表面上的聚合物层，所述聚合物层包括醛酮聚合物，其中，将所述醛酮聚合物制成片状结构体；所述片状结构体在(Tm+20)℃下经动态频率扫描测试获得弹性模量G’-耗能模量G”曲线，所述弹性模量G’-耗能模量G”曲线的斜率为K，0.8≤K＜∞，Tm℃表示所述醛酮聚合物的熔融温度。
由此，本申请实施方式的聚合物满足上述范围时，可以降低分子链缠结状态，有利于电解液在分子链之间的扩散；并且，聚合物仍保持有一定的分子链缠结状态，能够将电解液锁于聚合物内部，且能够降低聚合物溶解于电解液的风险，提高聚合物性能的稳定性；聚合物和电解液能够在隔离膜和极片之间构建形成三维连通的界面，该界面具有网状结构，有利于提高活性离子例如锂离子从电解液相扩散到极片的速率，并提高隔离膜的电导率，降低浓差极化，使得活性离子快速嵌入至极片中，并均匀沉积，从而提高电池单体的存储性能。
在一些实施方式中，0.8≤K≤100；可选地，0.8≤K≤10。
在一些实施方式中，醛酮聚合物在70℃下加入第一溶剂中形成醛酮聚合物体系；醛酮聚合物体系在70℃下静置8h，在25℃下静置≥24h后，将醛酮聚合物体系经200目滤网过滤后剩余第一物质，其中，醛酮聚合物的质量为q，其单位为g；所述第一物质的质量为m，其单位为g；醛酮聚合物和第一物质满足：5≤m/q≤1000。本申请实施方式 通过提高温度可以在电池单体安全工作温度范围内实现聚合物分子链的舒展，促进聚合物分子链与电解液的相互吸引与物理结合。常温下醛酮聚合物分子链段活性降低，保持在隔离本体表面附着并将电解液锁在聚合物所在空间环境，形成凝胶或类似凝胶的状态，能够提升活性离子例如锂离子的传输速率，改善存储性能。
在一些实施方式中，所述醛酮聚合物的玻璃化转变温度为Tg，其单位为℃，-100≤Tg≤50；可选地，-80≤Tg≤30。聚合物的玻璃化转变温度相对较低，分子链的链段柔性更好，相邻分子链更容易被打开。
在一些实施方式中，所述醛酮聚合物包括式(I)所示的结构单元，
式(I)中，R1包括单键、取代或未取代的C1-C6亚甲基；R2包括氢原子、取代或未取代的C1-C6烷基；可选地，R1包括单键、取代或未取代的C1-C4亚甲基；R2包括氢原子、取代或未取代的C1-C3烷基。
在一些实施方式中，所述醛酮聚合物包括式(I-1)所示的结构单元至式(I-6)所示的结构单元中的至少一者，
在一些实施方式中，所述醛酮聚合物包括式(II)所示的结构单元，
式(II)中，R3至R6各自独立地包括氢原子、羟基、取代或未取代的C1-C3烷基、取代或未取代的C1-C3羟烷基或者取代或未取代的C1-C3烷氧基；r和s各自独立地选自0至5中的整数，且r和s中至少一者选自正整数。
可选地，R3至R6各自独立地包括氢原子、羟基、取代或未取代的C1-C3烷基、取代或未取代的C1-C2羟烷基或者取代或未取代的C1-C2烷氧基。
在一些实施方式中，所述醛酮聚合物包括式(II-1)所示的结构单元至式(II-4)所示的结构单元中的至少一者，
在一些实施方式中，n选自500至15000的正整数。
在一些实施方式中，所述醛酮聚合物的分子量为1.2×105g/mol至1.0×106g/mol。
醛酮聚合物的分子量在上述范围时，能够使得醛酮聚合物的分子链在电解液中得到舒展，但是不易被电解液完全溶解分散，有利于调控醛酮聚合物分子链在电解液中均匀分布与分散；并且能够进一步提高醛酮聚合物的分子链之间的柔性，分子链之间的作用力相对较弱，有利于电解液中的溶剂分子打开分子链进入分子链之间，并被分子链所包裹，由此有利于活性离子通过溶剂进入活性物质内，实现活性离子的顺利和快速迁移。
在一些实施方式中，所述隔离本体包括基材，所述聚合物层设置于所述基材至少一个表面上。
在一些实施方式中，所述隔离本体包括基材和耐热涂层，所述耐热涂层设置于所述基材至少一个表面上，所述耐热涂层背离所述基材的表面上设置有所述聚合物层。
在一些实施方式中，所述聚合物层还包括耐热颗粒。耐热颗粒和醛酮聚合物协同作用，可以进一步提升隔离膜整体的耐热性能和离子传输性能等。
在一些实施方式中，基于所述聚合物层的总质量计，所述醛酮聚合物的质量百 分含量与所述耐热颗粒的质量百分含量的比值为(0.2至5)：1；可选为(0.5至2)：1。耐热颗粒和醛酮聚合物的含量在上述范围时，可以进一步提升隔离膜整体的耐热性能和离子传输性能等。
在一些实施方式中，所述聚合物层的涂布克重可以为0.5mg/1540.25mm2至5mg/1540.25mm2。聚合物层的涂布克重在上述范围时，能够进一步提升隔离膜整体的耐热性能和离子传输性能等。
第二方面，本申请提出了一种电池单体，包括如本申请第一方面任一实施方式所述的隔离膜。
第三方面，本申请提出了一种电池，包括如本申请第二方面任一实施方式所述的电池单体。
第四方面，本申请提出了一种用电装置，包括如本申请第三方面任一实施方式所述的电池。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，显而易见地，下面所描述的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据附图获得其他的附图。
图1是本申请的电池单体的一实施方式的示意图。
图2是图1的电池单体的实施方式的分解示意图。
图3是本申请的电池模块的一实施方式的示意图。
图4是本申请的电池包的一实施方式的示意图。
图5是图4所示的电池包的实施方式的分解示意图。
图6是包含本申请的电池单体作为电源的用电装置的一实施方式的示意图。
附图未必按照实际的比例绘制。
附图标记说明如下：
1、电池包；2、上箱体；3、下箱体；4、电池模块；
5、电池单体；51、壳体；52、电极组件；
53、盖板；
6、用电装置。
具体实施方式
以下，详细说明具体公开了本申请的隔离膜、电池单体、电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员 充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，方法包括步骤(a)和(b)，表示方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，提到方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到方法，例如，方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
在本申请中，术语“多个”、“多种”是指两个或两种以上。
术语“烷基”涵盖直链和支链烷基。例如，烷基可为C1-C5烷基、C1-C4烷基、C1-C3烷基、C1-C2烷基。在一些实施例中，烷基包括甲基、乙基、丙基、异丙基、丁基、异丁基等。另外，烷基可以是任选地被取代的。当经取代时，取代基包括氟原子。
术语“烷氧基”是指烷基与氧原子以单键连接的基团。例如烷氧基可以为C1至C5烷氧基、C1至C3烷氧基、C1至C2烷氧基。在一些实施例中，烷氧基可以包括甲氧基、乙氧基、丙氧基。另外，烷氧基可以是任选地被取代的。
术语“卤素原子”是指氟原子、氯原子、溴原子等。
术语“氢”是指1H(氕，H)、2H(氘，D)或3H(氚，T)。在各实施例中，“氢”可以是1H(氕，H)。
电池单体包括正极极片、负极极片、隔离膜和电解液。隔离膜位于正极极片和负极极片之间，以隔绝正极极片和负极极片。极片和电解液之间具有固液接触界面，在该接触界面可能会发生副反应，恶化电池单体的性能。以正极极片为例进行说明，正极极片所包含的正极活性物质和电解液之间具有固液接触界面，在该界面中正极活性物质可能会与电解液发生副反应，使得电池单体的存储性能恶化，并且副反应可能会产生不利于电池单体循环的产物，从而恶化电池单体的存储性能。
鉴于上述问题，本申请实施方式从构建界面的角度出发，提出了一种隔离膜，该隔离膜包括隔离本体和设置于隔离本体至少一个表面上的聚合物层，聚合物层中的聚合物分子链具有链段柔性，在隔离膜应用于电池单体时，聚合物层与电解液相接触，聚合物分子链舒展打开，电解液能够扩散至分子链之间，在隔离膜和极片之间构建形成三维连通的界面，该界面具有网状结构，有利于提高活性离子例如锂离子从电解液相扩散到极片的速率，并提高隔离膜的电导率，降低浓差极化，使得活性离子快速嵌入至极片中，并均匀沉积，从而提高电池单体的存储性能。
隔离膜
第一方面，本申请实施方式提出了一种隔离膜，所述隔离膜包括隔离本体和设置于隔离本体至少一个表面上的聚合物层，所述聚合物层包括醛酮聚合物，其中，将所述醛酮聚合物制成片状结构体；所述片状结构体在(Tm+20)℃下经动态频率扫描测试获得弹性模量G’-耗能模量G”曲线，所述弹性模量G’-耗能模量G”曲线的斜率为K，0.8≤K＜∞，Tm℃表示所述醛酮聚合物的熔融温度。
具体地，片状结构体的制备过程如下：将聚合物于80℃下真空干燥12h。将干燥后的聚合物通过平板硫化机热压成薄片，热压温度设定为(Tm+20)℃，压延厚度为1-2min，压延时间为2min，压力为8MPa。压延2min后将样品取出，放置在同型号另一台硫化机上冷压，冷压压力为10MPa。采用直径25mm的圆形模具即可获得固定10尺寸的聚合物圆片(片状结构体)。示例性地，片状结构体可以为厚度1-2mm，直径25mm的圆片；也可以根据测试设备所需的样品标准制样。
根据经典线性粘弹性的结论，对于聚合物，弹性模量G’-耗能模量G”曲线的末端区(趋近角速度最大值的区间范围)中弹性模量G’-耗能模量G”符合频率依赖性，聚合物的最长链对黏弹性行为起作用。
动态频率扫描测试的具体步骤如下：采用TA-AR2000EX旋转流变仪(TAinstruments，美国)进行动态频率扫描测试，平行板直径为25mm，厚度为0.9mm。为确保测试在线性點弹区，动态频率扫描测试时应变为2％，测试温度为Tm+20℃，测试的频率扫描范围：500rad/s≤w2≤0.05rad/s，以便能获取尽量低频区的数据。
动态频率扫描测试可以表征固相融化(熔体状态)下分子链的缠结程度，相比于线性结构或者短支链结构，长支化结构、网状结构和低交联结构缠结程度高，会表现出偏离线性末端行为，聚合物表现出固相行为。本申请的聚合物满足上述范围时，可以进一步降低分子链缠结状态，有利于电解液在分子链之间的扩散；并且，聚合物仍保持有一定的分子链缠结状态，能够将电解液锁于聚合物内部，且能够降低聚合物 溶解于电解液的风险，提高聚合物性能的稳定性；聚合物和电解液能够在隔离膜和极片之间构建形成三维连通的界面，该界面具有网状结构，有利于提高活性离子例如锂离子从电解液相扩散到极片的速率，并提高隔离膜的电导率，降低浓差极化，使得活性离子快速嵌入至极片中，并均匀沉积，从而提高电池单体的存储性能。
在一些实施方式中，0.8≤K≤100；可选地，0.8≤K≤10。
示例性地，K可以为0.8、1、1.01、1.1、1.2、1.5、2、5、10、15、20、30、50、100、200、500、1000、5000、10000或是上述任意两个数值组成的范围。
在一些实施方式中，所述醛酮聚合物的玻璃化转变温度为Tg，其单位为℃，-100≤Tg≤50；可选地，-80≤Tg≤30。
玻璃化转变温度是聚合物的链段从冻结到运动的转变温度，玻璃化转变温度对聚合物分子链的柔性具有一定影响，玻璃化转变温度越低，则常温下聚合物分子链的柔性越好，玻璃化转变温度越高，则常温下分子链的柔性越差。玻璃化温度可以采用差示扫描量热法DSC测得，具体地，测试步骤为：取0.5g至0.8g样品，将样品放置于载物坩埚中，在氮气气氛下对样品进行升降温处理，以10℃/min升温速度从比材料本征Tg低20℃的初始温度升温到材料本征Tm高20℃过程的截止温度，根据过程中材料的吸热放热峰值或转变点确定材料实际的玻璃化转变温度Tg和熔融温度Tm等。
聚合物的玻璃化转变温度相对较低，分子链的链段柔性更好，相邻分子链更容易被打开。示例性地，醛酮聚合物的玻璃化转变温度可以为-100℃、-90℃、-80℃、-60℃、-30℃、0℃、30℃、50℃或是上述任意两个数值组成的范围。
在一些实施方式中，所述醛酮聚合物包括式(I)所示的结构单元，
式(I)中，R1包括单键、取代或未取代的C1-C6亚甲基；R2包括氢原子、取代或未取代的C1-C6烷基；
可选地，R1包括单键、取代或未取代的C1-C4亚甲基。
可选地，R1包括单键、取代或未取代的C1-C2亚甲基。
可选地，R2包括氢原子、取代或未取代的C1-C3烷基。
在本申请实施方式中，单键表示基团不存在，基团两侧的原子以单键相连，例如R1为单键，表示R1两侧的碳原子以单键形式连接。
示例性地，所述醛酮聚合物包括式(I-1)所示的结构单元至式(I-6)所示的结构单元中的至少一者，
示例性地，所述醛酮聚合物包括式(II)所示的结构单元，
式(II)中，R3至R6各自独立地包括氢原子、羟基、取代或未取代的C1-C3烷基、取代或未取代的C1-C3羟烷基或者取代或未取代的C1-C3烷氧基；r和s各自独立地选自0至5中的整数，且r和s中至少一者选自正整数。
可选地，R3至R6各自独立地包括氢原子、羟基、取代或未取代的C1-C3烷基、取代或未取代的C1-C2羟烷基或者取代或未取代的C1-C2烷氧基。
在一些实施方式中，所述醛酮聚合物包括式(II-1)所示的结构单元至式(II-4)所示的结构单元中的至少一者，

上述醛酮聚合物的分子链纠缠结程度较低，有利于提高分子链的柔性，分子链能够在电解液中充分舒展，由此能够进一步改善界面性能。
上述聚合物仅为主要分子链的结构基团的举例，在本申请的实施方式中，聚合物还可以为上述结构基团与少量其它类型的结构基团(例如烯烃类结构单元、酯类单体、腈类单体、酰胺类单体等结构单元等)进行共聚获得。
本申请的聚合物的基团可以采用红外分光光度法IR进行检测，具体地，聚合物用ThermoNicoletNexus670衰减全反射傅里叶转换红外光谱仪(FTIR-ATR)进行测试，然后参照标准GB/T6040-2002进行测试，测试范围:ATR方法600～4000cm-1；重复性:±2cm-1；分辨率:优于4cm-1；透射深度0.2～0.6μm。
本申请的聚合物的结构可以采用核磁共振NMR测试，具体地，1HNMR和13CNMR在VarianMercuryPlus-400核磁共振仪上进行，测试温度为20℃，TMS为内标，CDCl3作为溶剂，质子共振频率为400MHz。
本申请的聚合物单体类型(尤其适用于聚合物中占比较少的单体)可以采用裂解-气相色谱-质谱联用进行，具体测试步骤如下：准确称取0.5mg样品装入样品杯，固定于进样杆后，装入安装在GC(气相色谱)进样口附近的裂解器，待裂解器温度达到设定温度后，按下进样按钮，样品杯通过自由落体迅速掉入裂解炉炉心，在惰性气体N2氛围中，挥发性成分瞬间气化，由载气带入气相色谱柱中进行分离，最后通过火焰离子化检测仪FID或质谱仪MS检出，从而得到气相色谱图或总离子流图。
上述基团经取代时，取代基可以包括腈基(-CN)、硝基、磺酸基、磺酰基、羧基、酰胺、羧基、酯基、卤素原子例如氯原子、氟原子、溴原子中的一种或多种。上述取代基为耐高压取代基，更有利于稳定聚合物的结构。
在一些实施方式中，n选自500至15000的正整数。
可选地，n选自500至10000的正整数。
在一些实施方式中，所述聚合物的分子量为1.2×105g/mol至1.0×106g/mol。
醛酮聚合物的分子量在上述范围时，能够使得醛酮聚合物的分子链在电解液中得到舒展，但是不易被电解液完全溶解分散，有利于调控醛酮聚合物分子链在电解液中均匀分布与分散；并且能够进一步提高醛酮聚合物的分子链之间的柔性，分子链之间的作用力相对较弱，有利于电解液中的溶剂分子打开分子链进入分子链之间，并被分子链所包裹，由此有利于活性离子通过溶剂进入活性物质内，实现活性离子的顺利和快速迁移。示例性地，醛酮聚合物的分子量可以为1.2×105g/mol、2×105g/mol、5×105g/mol、8×105g/mol、1×106g/mol或是上述任意两个数值组成的范围。
聚合物的分子量为本领域公知的含义，可以采用本领域常用的设备和方法进行测定，可以采用凝胶渗透色谱法GPC测试，具体测试步骤为：取待测样品适量(样品浓度保证8％-12％遮光度即可)，加入20ml去离子水，同时外超5min(53KHz/120W)， 确保样品完全分散，之后按照GB/T19077-2016/ISO13320:2009标准对样品进行测定。
或者采用多角激光散射仪MALLS进行测试，具体地，采用GPC与DawnHeleosⅡ型多角激光光散射装置，OptilabT-rEX折光率(RI)检测器和ViscoStarⅡ型粘度计联用的仪器(WyattTechnologyCorporation,美国)。测试在30°条件进行，采用四氢呋喃作为流动相，以1.0ml/min的流速测试，采用商用软件ASTRA6处理SEC-SAMLL数据取得分子量参数。
本申请实施方式中的聚合物还满足以下条件中的一个或多个时，能够进一步改善电池单体的循环性能和存储性能。
在一些实施方式中，醛酮聚合物在70℃下加入第一溶剂中形成醛酮聚合物体系；所述醛酮聚合物体系在70℃下静置8h，在25℃下静置≥24h后，经历两个阶段的静置处理后，醛酮聚合物体系部分经溶胀、吸附转变为凝胶状态物质，继而将所述醛酮聚合物体系经200目滤网过滤后剩余第一物质。醛酮聚合物的质量为q，其单位为g；所述第一物质的质量为m，其单位为g；所述醛酮聚合物和所述第一物质满足：5≤m/q≤1000；可选地，10≤m/q≤1000；进一步可选地，10≤m/q≤50。示例性地，m/q可以为5、10、20、25、28、30、32、35、40、50、80、100、200、500、1000或是上述任意两个数值组成的范围。
示例性地，基于聚合物体系的质量，聚合物的质量含量和第一溶剂的质量含量的比值范围为1：100至1:10，例如3:50。
示例性地，第一溶剂与电解液的溶剂相同或相似，第一溶剂可以包括碳酸酯类溶剂和醚类溶剂中的至少一种。例如，碳酸酯类溶剂包括环状碳酸酯溶剂和/或线性碳酸酯溶剂。
作为环状碳酸酯溶剂的示例，环状碳酸酯溶剂包括碳酸乙烯酯EC、碳酸亚乙烯酯VC、氟代碳酸乙烯酯FEC、二氟代碳酸乙烯酯DFEC、乙烯基碳酸乙烯酯VEC和碳酸二辛酯CC中的一种或多种。
作为线性碳酸酯溶剂的示例，线性碳酸酯溶剂包括碳酸二甲酯DMC、碳酸二乙酯DEC、碳酸甲乙酯EMC、碳酸二苯酯DPC、碳酸甲基烯丙酯MAC和聚碳酸酯VA中的一种或多种。
作为醚类溶剂的示例，醚类溶剂包括四氢呋喃THF、2-甲基四氢呋喃2me-thf、1,3-二氧环戊烷DOL、二甲氧基甲烷DMM、1,2-二甲氧基乙烷DME和二甘醇二甲醚DG中的一种或多种。
可选地，第一溶剂还可以同时包含锂盐和电解液添加剂，如六氟磷酸锂、碳酸亚乙烯酯VC、氟代碳酸亚乙烯酯FEC等。
在本申请中，m/q也称为沉淀值，其表征了聚合物和电解液转变为凝胶状态物质的能力。
第一物质主要包括聚合物和第一溶剂所形成的凝胶状态物质，该类凝胶状态物质中，聚合物的分子结构基本不会发生变化。
在一些实施方式中，将第一物质于80℃下干燥12h，以去除第一物质中的第一 溶剂，经红外分光光度法IR进行检测或核磁共振NMR测试，第一物质在干燥后主要成分为前文所述的聚合物。
本申请实施方式通过提高温度可以在电池单体安全工作温度范围内实现聚合物分子链的舒展，促进聚合物分子链与电解液的相互吸引与物理结合。常温下醛酮聚合物分子链段活性降低，保持在隔离本体表面附着并将电解液锁在聚合物所在空间环境，形成凝胶或类似凝胶的状态，能够提升活性离子例如锂离子的传输速率，改善循环性能和存储性能。
本申请实施方式中，隔离膜包括隔离本体和聚合物层，聚合物层设置于隔离本体至少一个表面，意味着聚合物层可以设置于隔离本体的其中一个表面，也可以设置于隔离本体的两个表面上。由于隔离本体具有多种结构形式，相应地，聚合物层具有多种设置形式。醛酮聚合物可以分散于溶剂中形成聚合物混合体系，该聚合物混合体系经雾化喷涂、凹版涂布等涂布工艺涂布于隔离本体上。
在一些实施方式中，隔离本体包括基材，聚合物层设置于基材至少一个表面上。
在另一些实施方式中，隔离本体包括基材和耐热涂层，耐热涂层设置于基材至少一个表面上，所述耐热涂层背离所述基材的表面上设置有所述聚合物层。可以理解的是，耐热涂层可以设置于基材的其中一个表面，或者设置于基材的两个表面。
本申请实施方式对基材的材质没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的基材，例如，所述基材可包括多孔聚烯烃基树脂膜(例如聚乙烯、聚丙烯、聚偏氟乙烯中的至少一种)、多孔玻璃纤维和多孔无纺布中的至少一种。所述基材可以是单层薄膜，也可以是多层复合薄膜。所述基材为多层复合薄膜时，各层的材料可以相同，也可以不同。
在一些实施方式中，所述基材的孔隙率大于或等于25％；可选为25％至50％。基材的孔隙率在上述范围时，可以提升基材的透气率有利于活性离子的迁移，且由于孔隙率相对较小，还可以提升基材的机械性能，并为聚合物层起到良好的支撑作用。
在一些实施方式中，所述基材的厚度可为小于或等于16μm，可选为5μm至12μm。示例性地，基材的厚度可以为1μm、2μm、3μm、5μm、10μm、12μm、15μm、16μm或是上述任意两个数值组成的范围。
耐热涂层可以包括耐热颗粒。在一些实施方式中，耐热颗粒包括无机颗粒和有机颗粒中的至少一种。通过加入耐热颗粒，可以改善隔离膜的耐热性能。
在一些实施方式中，无机颗粒在耐热涂层中的质量百分含量≤30。示例性地，无机颗粒在耐热涂层中的质量百分含量为1％、2％、3％、4％、5％、6％、7％、8％、9％、10％、15％、20％、25％、30％或是上述任意两个数值组成的范围。
无机颗粒可包括具有5或更高的介电常数的无机颗粒、具有传输活性离子能力的无机颗粒、能够发生电化学氧化和还原的无机颗粒中的至少一种。
在一些实施方式中，具有5或更高的介电常数的无机颗粒可包括勃姆石(γ-AlOOH)、氧化铝(Al2O3)、硫酸钡(BaSO4)、氧化镁(MgO)、氢氧化镁(Mg(OH)2)、硅氧化合物SiOx(0＜x≤2)、二氧化锡(SnO2)、氧化钛(TiO2)、氧化 钙(CaO)、氧化锌(ZnO)、氧化锆(ZrO2)、氧化钇(Y2O3)、氧化镍(NiO)、二氧化铪(HfO2)、氧化铈(CeO2)、钛酸锆(ZrTiO3)、钛酸钡(BaTiO3)、氟化镁(MgF2)、Pb(Zr,Ti)O3(简写为PZT)、Pb1-mLamZr1-nTinO3(简写为PLZT，0＜m＜1，0＜n＜1)和Pb(Mg3Nb2/3)O3-PbTiO3(简写为PMN-PT)中的至少一种。
在一些实施方式中，具有传输活性离子能力的无机颗粒可包括磷酸锂(Li3PO4)、磷酸钛锂(LixTiy(PO4)3，0＜x＜2，0＜y＜3)、磷酸钛铝锂(LixAlyTiz(PO4)3，0＜x＜2，0＜y＜1，0＜z＜3)、(LiAlTiP)xOy类玻璃(0＜x＜4，0＜y＜13)、钛酸镧锂(LixLayTiO3，0＜x＜2，0＜y＜3)、硫代磷酸锗锂(LixGeyPzSw，0＜x＜4，0＜y＜1，0＜z＜1，0＜w＜5)、氮化锂(LixNy，0＜x＜4，0＜y＜2)、SiS2类玻璃(LixSiySz，0＜x＜3，0＜y＜2，0＜z＜4)和P2S5类玻璃(LixPySz，0＜x＜3，0＜y＜3，0＜z＜7)中的至少一种。
在一些实施方式中，能够发生电化学氧化和还原的无机颗粒可包括含锂过渡金属氧化物、橄榄石结构的含锂磷酸盐、碳基材料、硅基材料、锡基材料和锂钛化合物中的至少一种。
在一些实施方式中，耐热涂层还可以包括其它有机颗粒，例如有机颗粒可包括聚苯乙烯、聚乙烯、聚酰亚胺、三聚氰胺树脂、酚醛树脂、聚丙烯、聚酯(例如聚对苯二甲酸乙二酯、聚萘二甲酸乙二酯、聚对苯二甲酸丁二酯)、聚苯硫醚、聚芳酰胺、聚酰胺酰亚胺、聚酰亚胺、丙烯酸丁酯与甲基丙烯酸乙酯的共聚物及其混合物中的至少一种。
在一些实施方式中，耐热涂层还可包括粘结剂。作为示例，所述粘结剂可包括水溶液型丙烯酸类树脂(例如，丙烯酸、甲基丙烯酸、丙烯酸钠单体均聚物或与其他共聚单体共聚物)、聚乙烯醇(PVA)、异丁烯-马来酸酐共聚物和聚丙烯酰胺中的至少一种。
在一些实施方式中，所述耐热涂层的厚度可≤4μm。由此有助于提升电池单体的能量密度。在本申请实施方式中，耐热涂层的厚度是指位于基材单侧的耐热涂层的厚度。示例性地，耐热涂层的厚度可以为0.1μm、0.5μm、1μm、1.5μm、2μm、2.5μm、3μm、3.5μm、4μm或是上述任意两个数值组成的范围。
在一些实施方式中，聚合物层还可以包括耐热颗粒，耐热颗粒和醛酮聚合物协同作用，可以进一步提升隔离膜整体的耐热性能和离子传输性能等。醛酮聚合物和耐热颗粒可以分散于溶剂中形成聚合物混合体系，该聚合物混合体系经雾化喷涂、凹版涂布等涂布工艺涂布于隔离本体上。
在一些实施方式中，基于所述聚合物层的总质量计，所述醛酮聚合物的质量百分含量与所述耐热颗粒的质量百分含量的比值为(0.2至5.0)：1；可选为(0.5至2.0)：1。耐热颗粒和醛酮聚合物的含量在上述范围时，可以进一步提升隔离膜整体的耐热性能和离子传输性能等。示例性地，醛酮聚合物的质量百分含量与所述耐热颗粒的质量百分含量的比值可以为0.2：1、0.3：1、0.4：1、0.5：1、0.6：1、0.8：1、1.0：1、1.2：1、1.5：1、1.8：1、2.0：1、2.5：1、2.8：1、3.0：1、3.2：1、3.5：1、3.8： 1、4.0：1、4.2：1、4.5：1、4.8：1、5.0：1或是上述任意两个数值组成的范围。
在一些实施方式中，所述聚合物层的涂布克重可以为0.5mg/1540.25mm2至5mg/1540.25mm2。聚合物层的涂布克重在上述范围时，能够进一步提升隔离膜整体的耐热性能和离子传输性能等。
可选地，聚合物层的涂布克重可以为0.5mg/1540.25mm2至3.5mg/1540.25mm2。
示例性地，聚合物层的涂布克重可以为0.5mg/1540.25mm2、0.6mg/1540.25mm2、0.8mg/1540.25mm2、1.0mg/1540.25mm2、1.2mg/1540.25mm2、1.5mg/1540.25mm2、1.8mg/1540.25mm2、2.0mg/1540.25mm2、2.5mg/1540.25mm2、3mg/1540.25mm2、3.5mg/1540.25mm2、4mg/1540.25mm2、4.5mg/1540.25mm2、5mg/1540.25mm2或是上述任意两个数值组成的范围。
在本申请实施方式中聚合物层的涂布克重是指单面克重，例如基材的两面均设置有聚合物层，则此处是指基材的一面上聚合物层的涂布克重。
涂布克重为本领域公知的含义，可以采用本领域公知的设备和方法进行检测，通过将同一母卷基材与隔离膜裁剪成1540.25mm2的小圆片，分别称取10片隔离膜小圆片重量，通过计算可得到所述隔离膜中聚合物的涂布克重。
电池单体
第二方面，本申请实施方式提出了一种电池单体，所述电池单体包括电极组件和电解质，所述电极组件包括正极极片、负极极片和隔离膜，所述隔离膜设置于所述正极极片和负极极片之间，隔离膜包括如本申请第一方面任一实施方式的隔离膜。
[正极极片]
所述正极极片包括正极集流体和设置于正极集流体至少一个表面上的正极活性物质层。
作为示例，正极集流体具有在自身厚度方向相对的两个表面，正极活性物质层设置于正极集流体的两个相对表面中的任意一者或两者上。
所述正极活性物质层包括正极活性物质，所述正极活性物质可采用本领域公知的用于电池单体的正极活性物质。作为示例，正极活性物质可包括以下材料中的至少一种：含锂磷酸盐化合物、含锂过渡金属氧化物、含钠磷酸盐化合物和含钠过渡金属氧化物。
示例性地，橄榄石型磷酸盐活性物质(含锂磷酸盐化合物)的通式为：LixAyMeaMbP1-cXcYz，其中，0≤x≤1.3，0≤y≤1.3，且0.9≤x+y≤1.3；0.9≤a≤1.5，0≤b≤0.5，且0.9≤a+b≤1.5；0≤c≤0.5；3≤z≤5；A包括Na、K、Mg中的一种或几种；Me包括Mn、Fe、Co、Ni中的一种或几种；M包括B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；X包括S、Si、Cl、B、C、N中的一种或几种；Y包括O、F中的一种或几种。具体地，橄榄石型磷酸盐活性物质包括LiFePO4、LiMnPO4、LiNiPO4、和LiCoPO4中的一种或多种。
示例性地，锂过渡金属氧化物(层状材料例如三元、镍酸锂/钠、钴酸锂/钠、 锰酸锂/钠、富锂层状和岩盐相层状等材料)。层状结构正极活性物质的通式为：LixAyNiaCobMncM(1-a-b-c)Yz，其中，0≤x≤2.1，0≤y≤2.1，且0.9≤x+y≤2.1；0≤a≤1，0≤b≤1，0≤c≤1，且0.1≤a+b+c≤1；1.8≤z≤3.5；A包括Na、K、Mg中的一种或几种；M包括B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Fe、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；Y包括O、F中的一种或几种。可选地，y＝0。具体地，层状结构正极活性物质可以包括钴酸锂LCO、镍酸锂LNO、锰酸锂LMO、LiNi1/3Co1/3Mn1/3O2(NCM333)、LiNi0.5Co0.2Mn0.3O2(NCM523)、LiNi0.6Co0.2Mn0.2O2(NCM622)、LiNi0.8Co0.1Mn0.1O2(NCM811)和NCA中的一种或多种。
在一些实施方式中，正极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铝箔或铝合金箔。复合集流体可包括高分子材料基层以及形成于高分子材料基层至少一个表面上的金属材料层，作为示例，金属材料可包括选自铝、铝合金、镍、镍合金、钛、钛合金、银和银合金中的一种或多种的组合，高分子材料基层可包括选自聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)和聚乙烯(PE)中的一种或多种的组合。
在一些实施方式中，正极活性物质层还可选地包括正极导电剂。本申请实施方式对正极导电剂的种类没有特别的限制，作为示例，正极导电剂包括选自超导碳、导电炭黑、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的一种或多种的组合。在一些实施方式中，基于正极活性物质层的总质量，正极导电剂的质量百分含量在5％以下。
在一些实施方式中，正极活性物质层还可选地包括正极粘结剂。本申请实施方式对正极粘结剂的种类没有特别的限制，作为示例，正极粘结剂可包括选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物和含氟丙烯酸酯类树脂中的一种或多种的组合。在一些实施方式中，基于正极活性物质层的总质量，正极粘结剂的质量百分含量在5％以下。相较于本申请实施方式的醛酮聚合物的结晶度，正极粘结剂的结晶度更高。相较于本申请实施方式的醛酮聚合物的熔融温度，正极粘结剂的熔融温度更高。
正极活性物质层通常是将正极浆料涂布在正极集流体上，经干燥、冷压而成的。正极浆料通常是将正极活性物质、可选的导电剂、可选的粘结剂以及任意的其他组分分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)，但不限于此。当然正极极片的制备不限于上述方法，还可以采用前文所述的制备方法。
[负极极片]
在一些实施方式中，所述负极极片包括负极集流体以及设置在所述负极集流体至少一个表面且包括负极活性物质的负极活性物质层。
示例性地，所述负极集流体具有在自身厚度方向相对的两个表面，所述负极活性物质层设置在所述负极集流体的两个相对表面中的任意一者或两者上。
所述负极活性物质可采用本领域公知的用于电池单体的负极活性物质。作为示例，所述负极活性物质可包括但不限于天然石墨、人造石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂中的至少一种。所述硅基材料可包括单质硅、硅氧化物、硅碳复合物、硅氮复合物和硅合金材料中的至少一种。所述锡基材料可包括单质锡、锡氧化物和锡合金材料中的至少一种。
在一些实施方式中，所述负极活性物质层还可选地包括负极导电剂。本申请实施方式对所述负极导电剂的种类没有特别的限制，作为示例，所述负极导电剂可包括超导碳、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的至少一种。在一些实施方式中，基于所述负极活性物质层的总质量，所述负极导电剂的质量百分含量为≤5％。
在一些实施方式中，所述负极活性物质层还可选地包括负极粘结剂。本申请实施方式对所述负极粘结剂的种类没有特别的限制，作为示例，所述负极粘结剂可包括丁苯橡胶(SBR)、水溶性不饱和树脂SR-1B、水性丙烯酸类树脂(例如，聚丙烯酸PAA、聚甲基丙烯酸PMAA、聚丙烯酸钠PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)和羧甲基壳聚糖(CMCS)中的至少一种。在一些实施方式中，基于所述负极活性物质层的总质量，所述负极粘结剂的质量百分含量为≤5％。
在一些实施方式中，所述负极活性物质层还可选地包括其他助剂。作为示例，其他助剂可包括增稠剂，例如，羧甲基纤维素钠(CMC)、PTC热敏电阻材料等。在一些实施方式中，基于所述负极活性物质层的总质量，所述其他助剂的质量百分含量为≤2％。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铜箔。所述复合集流体可包括高分子材料基层以及形成于所述高分子材料基层至少一个表面上的金属材料层。作为示例，所述金属材料可包括铜、铜合金、镍、镍合金、钛、钛合金、银和银合金中的至少一种。作为示例，所述高分子材料基层可包括聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)和聚乙烯(PE)中的至少一种。
所述负极活性物质层通常是将负极浆料涂布在负极集流体上，经干燥、冷压而成的。所述负极浆料通常是将负极活性物质、可选的导电剂、可选地粘结剂、其他可选的助剂分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水，但不限于此。当然负极极片的制备不限于上述方法，还可以采用前文所述的制备方法。
所述负极极片并不排除除了所述负极活性物质层之外的其他附加功能层。例如在某些实施例中，本申请所述的负极极片还包括夹在所述负极集流体和所述负极活性物质层之间、设置在所述负极集流体表面的导电底涂层(例如由导电剂和粘结剂组成)。在另外一些实施例中，本申请所述的负极极片还包括覆盖在所述负极活性物质层表面的保护层。
[电解液]
在电池单体充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出，电解液在正极极片和负极极片之间起到传导活性离子的作用。本申请对电解液的种类没有特别的限制，可根据实际需求进行选择。
所述电解液包括电解质盐和溶剂。所述电解质盐和所述溶剂的种类不受具体的限制，可根据实际需求进行选择。
当本申请的电池单体为锂离子电池时，作为示例，所述电解质盐可包括但不限于六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、高氯酸锂(LiClO4)、六氟砷酸锂(LiAsF6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO2F2)、二氟二草酸磷酸锂(LiDFOP)和四氟草酸磷酸锂(LiTFOP)中的至少一种。
当本申请的电池单体为钠离子电池时，作为示例，所述电解质盐可包括但不限于六氟磷酸钠(NaPF6)、四氟硼酸钠(NaBF4)、高氯酸钠(NaClO4)、六氟砷酸钠(NaAsF6)、双氟磺酰亚胺钠(NaFSI)、双三氟甲磺酰亚胺钠(NaTFSI)、三氟甲磺酸钠(NaTFS)、二氟草酸硼酸钠(NaDFOB)、二草酸硼酸钠(NaBOB)、二氟磷酸钠(NaPO2F2)、二氟二草酸磷酸钠(NaDFOP)和四氟草酸磷酸钠(NaTFOP)中的至少一种。
作为示例，所述溶剂可包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸乙烯酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)、二乙砜(ESE)、四氢呋喃THF、2-甲基四氢呋喃2me-thf、1,3-二氧环戊烷DOL、二甲氧基甲烷DMM、1,2-二甲氧基乙烷DME和二甘醇二甲醚DG中的至少一种。
在一些实施方式中，所述电解液中还可选地包括添加剂。例如，所述添加剂可以包括负极成膜添加剂，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温功率性能的添加剂等。
在一些实施方式中，所述正极极片、所述隔离膜和所述负极极片可通过卷绕工艺和/或叠片工艺制成电极组件。
在一些实施方式中，所述电池单体可包括外包装。该外包装可用于封装上述电极组件及电解液。
在一些实施方式中，所述电池单体的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。所述电池单体的外包装也可以是软包，例如袋式软包。所述软包的材质可以是塑料，如聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)和聚丁二酸丁二醇酯(PBS) 中的至少一种。
在一些实施方式中，正极极片、隔离膜和负极极片可通过卷绕工艺或叠片工艺制成电极组件。
本申请对电池单体的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图1是作为一个示例的方形结构的电池单体5。
在一些实施例中，如图1和图2所示，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53用于盖设开口，以封闭容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于容纳腔。电解液浸润于电极组件52中。电池单体5所含电极组件52的数量可以为一个或多个，可根据需求来调节。
本申请的电池单体的制备方法是公知的。在一些实施例中，可将正极极片、隔离膜、负极极片和电解液组装形成电池单体。作为示例，可将正极极片、隔离膜、负极极片经卷绕工艺或叠片工艺形成电极组件，将电极组件置于外包装中，烘干后注入电解液，经过真空封装、静置、化成、整形等工序，得到电池单体。
在本申请的一些实施例中，根据本申请的电池单体可以组装成电池模块，电池模块所含电池单体的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图3是作为一个示例的电池模块4的示意图。如图3所示，在电池模块4中，多个电池单体5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电池单体5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个电池单体5容纳于该容纳空间。
在一些实施例中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
电池模块4和电池包均可以作为本申请实施方式中电池的具体示例。
图4和图5是作为一个示例的电池包1的示意图。如图4和图5所示，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2用于盖设下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
用电装置
第三方面，本申请提供一种用电装置，用电装置包括本申请的电池单体、电池模块和电池包中的至少一种。电池单体、电池模块和电池包可以用作用电装置的电源，也可以用作用电装置的能量存储单元。用电装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
用电装置可以根据其使用需求来选择电池单体、电池模块或电池包。图6是作 为一个示例的用电装置的示意图。该用电装置6为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对高功率和高能量密度的需求，可以采用电池包1或电池模块。作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该用电装置通常要求轻薄化，可以采用电池单体作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1锂离子电池的制备
(1)正极极片的制备：
采用厚度为12μm的铝箔作为正极集流体。
将正极活性物质LiNi0.6Co0.2Mn0.2O2(NCM622)、导电剂碳黑、粘结剂聚偏二氟乙烯(PVDF)在适量的N-甲基吡咯烷酮(NMP)中充分搅拌混合制成正极浆料。正极浆料中NCM622、导电碳黑、PVDF的质量比为97.5:1.4:1.1。将正极浆料涂布在集流体铝箔上并在100℃下真空干燥后进行冷压，然后进行切边、裁片、分条后，在85℃的真空条件下烘干4h，制成正极极片。
(2)负极极片的制备：
采用厚度为8μm的铜箔作为负极集流体。
将负极活性物质人造石墨、导电剂碳黑、粘接剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC)按照重量比为97.4：2：0.5：2.6混合均匀后加入去离子水中，制成负极浆料。将负极浆料涂布在集流体铜箔上并在85℃下烘干，然后进行冷压、切边、裁片、分条后，在120℃真空条件下烘干12h，制成负极极片。
(3)电解液的制备：
在含水量小于10ppm的环境下，将非水有机溶剂碳酸乙烯酯EC、碳酸甲乙酯(EMC)按照体积比3:7进行混合得到电解液溶剂，随后将锂盐LiPF6和混合后的溶剂混合，配置成锂盐浓度为1mol/L的电解液。
(4)隔离膜的制备
以8μm的聚乙烯薄膜(PE)作为基材。
将15g醛酮聚合物分散于100mL碳酸二甲酯DMC溶剂中形成混合体系，将混合体系雾化喷涂于聚乙烯薄膜的两个表面上，分别形成聚合物层。雾化溶剂采用水，混合体系的质量含量为1％。
(5)锂离子电池的制备：
将上述正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片之间起到隔离作用，然后卷绕得到电极组件；将电极组件置于外包装壳中，干燥后注入电解液，经过真空封装、静置、化成、整形等工序，得到锂离子电池。
对比例1
采用与实施例1相似的方法制备锂离子电池，与实施例1不同的是，对比例1中的隔离膜为7μm的聚乙烯薄膜(PE)。
对比例2
采用与实施例1相似的方法制备锂离子电池，与实施例1不同的是，对比例2中的隔离膜的醛酮聚合物更换了材质。
实施例2-1
采用与实施例1相似的方法制备锂离子电池，与实施例1不同的是，实施例2-1隔离膜的醛酮聚合物更换了材质。
实施例3-1至实施例3-5
采用与实施例1相似的方法制备锂离子电池，与实施例1不同的是，实施例3-1至实施例3-5调整了隔离膜的聚合物层的厚度。
实施例4-1
采用与实施例1相似的方法制备锂离子电池，与实施例1不同的是，实施例4-1调整了隔离膜的聚合物层的设置位置，具体地，隔离膜的制备步骤包括：
以7μm的聚乙烯薄膜(PE)作为隔离膜基材；
将硅氧化合物颗粒、粘结剂水溶液型聚丙烯酸按照质量比20：80在适量的溶剂去离子水中混合均匀，得到涂覆浆料。
将所配制的涂覆浆料用涂布机涂布在PE基材的2个表面上，形成耐热涂层。
将15g醛酮聚合物分散于100mL碳酸二甲酯DMC溶剂中形成混合体系，将混合体系雾化喷涂于耐热涂层的表面上，形成聚合物层，由此得到隔离膜。雾化溶剂采用水，混合体系的质量含量为1％。
实施例4-2至实施例4-6
采用与实施例1相似的方法制备锂离子电池，与实施例1不同的是，实施例4-2至实施例4-6调整了隔离膜的聚合物层的组成，具体地，隔离膜的制备步骤包括：
以7μm的聚乙烯薄膜(PE)作为隔离膜基材；
将硅氧化合物颗粒、15g醛酮聚合物分散于100mL碳酸二甲酯DMC溶剂中形成混合体系，将混合体系雾化喷涂于耐热涂层的表面上，形成聚合物层，由此得到隔离膜。其中，实施例4-2中硅氧化合物颗粒、醛酮聚合物的质量比为1.5:1；实施例4-3中硅氧化合物颗粒、醛酮聚合物的质量比为0.5:1；实施例4-4中硅氧化合物颗粒、醛酮聚合物的质量比为2:1；实施例4-5中硅氧化合物颗粒、醛酮聚合物的质量比为0.2:1；实施例4-5中硅氧化合物颗粒、醛酮聚合物的质量比为0.5:1。
实施例和对比例的数据如表1所示。
测试部分
1、锂离子电池容量保持率测试
将实施例和对比例制备的上述锂离子电池，在常温环境中以1/3C恒流充电至4.25V，再以4.25V恒定电压充电至电流为0.05C，搁置5min，再以1/3C放电至2.8V，所得容量记为初始容量C0。然后调至97％soc转移到60℃环境下进行存储。对上述同 一个电池重复以上步骤，并同时记录每30D电池的放电容量Cn，则每30D后电池容量保持率Pn＝Cn/C0*100％，以P1、P2……P5这5个点值为纵坐标，以对应的存储时间为横坐标，得到电池容量保持率与存储天数的点状图。表中电池容量保持率数据是在上述测试条件下存储150D之后测得的数据，即P5的值。
2、锂离子电池直流阻抗测试
将实施例和对比例制备的上述锂离子电池，在25℃下，以1/3C恒流充电至4.25V，再以4.25V恒定电压充电至电流为0.05C，搁置5min后，记录电压V1。然后再以1/3C放电30s，记录电压V2，则(V2-V1)/1/3C，得到第一次循环后电池的内阻DCR1。将该电池在常温环境中以1/3C恒流充电至4.25V，再以4.25V恒定电压充电至电流为0.05C，搁置5min，再以1/3C放电至2.8V，所得容量记为初始容量C0。然后调至97％soc转移到60℃环境下进行存储。每隔30D对上述同一个电池重复以上步骤，并同时记录第n次电池的内阻DCRn(n＝1、2、3……5)，将上述DCR1、DCR2、DCR3……DCR5这5个点值为纵坐标，以对应的循环次数为横坐标，得到电池放电DCIR的存储天数的曲线图。
表中电池内阻增大比率＝(DCRn-DCR1)/DCR1*100％，表中的数据是在上述测试条件下存储150D之后测得的数据。
测试结果
测试结果如表1所示。
表1
表1中，70％甲醛是指基于甲醛和聚乙烯醇的总摩尔量，甲醛的摩尔百分含量为70％。
由表1可知，相较于对比例1，本申请实施例在隔离膜中添加本申请的醛酮聚合物，锂离子电池的循环性能和存储性能具有改善。相较于对比例2，本申请实施例在满足0.8≤K＜∞，尤其是0.8≤K≤100；可选地，0.8≤K≤10时，其分子链排列趋向于疏松，分子链之间的作用力较小，相邻分子链容易被打开，并通过分子间内旋转实现链段运动，形成具有较高柔性的分子链结构，能够更显著地改善锂离子电池的循环性能和存储性能。
虽然已经参考优选实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (16)

  1. 一种隔离膜，包括：
    隔离本体；
    设置于所述隔离本体至少一个表面上的聚合物层，所述聚合物层包括醛酮聚合物，
    其中，
    将所述醛酮聚合物制成片状结构体；所述片状结构体在(Tm+20)℃下经动态频率扫描测试获得弹性模量G’-耗能模量G”曲线，所述弹性模量G’-耗能模量G”曲线的斜率为K，0.8≤K＜∞，Tm℃表示所述醛酮聚合物的熔融温度。
  2. 根据权利要求1所述的隔离膜，其中，0.8≤K≤100；可选地，0.8≤K≤10。
  3. 根据权利要求1或2所述的隔离膜，其中，所述醛酮聚合物在70℃下加入第一溶剂中形成醛酮聚合物体系；
    所述醛酮聚合物体系在70℃下静置8h，在25℃下静置≥24h后，所述醛酮聚合物体系经200目滤网过滤后剩余第一物质，
    其中，所述醛酮聚合物的质量为q，其单位为g；所述第一物质的质量为m，其单位为g；所述醛酮聚合物和所述第一物质满足：5≤m/q≤1000。
  4. 根据权利要求1至3中任一项所述的隔离膜，其中，所述醛酮聚合物的玻璃化转变温度为Tg，其单位为℃，-100≤Tg≤50；可选地，-80≤Tg≤30。
  5. 根据权利要求1至4中任一项所述的隔离膜，其中，所述醛酮聚合物包括式(I)所示的结构单元，
    式(I)中，
    R1包括单键、取代或未取代的C1-C6亚甲基；R2包括氢原子、取代或未取代的C1-C6烷基；
    可选地，R1包括单键、取代或未取代的C1-C2亚甲基；
    可选地，R2包括氢原子、取代或未取代的C1-C3烷基。
  6. 根据权利要求5所述的隔离膜，其中，所述醛酮聚合物包括式(I-1)所示的结构单元至式(I-6)所示的结构单元中的至少一者，

  7. 根据权利要求1至6中任一项所述的隔离膜，所述醛酮聚合物包括式(II)所示的结构单元，
    式(II)中，
    R3至R6各自独立地包括氢原子、羟基、取代或未取代的C1-C3烷基、取代或未取代的C1-C3羟烷基或者取代或未取代的C1-C3烷氧基；r和s各自独立地选自0至5中的整数，且r和s中至少一者选自正整数；
    可选地，
    R3至R6各自独立地包括氢原子、羟基、取代或未取代的C1-C3烷基、取代或未取代的C1-C2羟烷基或者取代或未取代的C1-C2烷氧基。
  8. 根据权利要求7所述的隔离膜，所述醛酮聚合物包括式(II-1)所示的结构单元至式(II-4)所示的结构单元中的至少一者，

  9. 根据权利要求5至8中任一项所述的隔离膜，其中，
    n选自500至15000的正整数；和/或
    所述醛酮聚合物的分子量为1.2×105g/mol至1.0×106g/mol。
  10. 根据权利要求1至9中任一项所述的隔离膜，其中，所述隔离本体包括基材，所述聚合物层设置于所述基材至少一个表面上。
  11. 根据权利要求1至9中任一项所述的隔离膜，其中，所述隔离本体包括基材和耐热涂层，所述耐热涂层设置于所述基材至少一个表面上，所述耐热涂层背离所述基材的表面上设置有所述聚合物层。
  12. 根据权利要求1至11中任一项所述的隔离膜，其中，所述聚合物层还包括耐热颗粒；
    可选地，基于所述聚合物层的总质量计，所述醛酮聚合物的质量百分含量与所述耐热颗粒的质量百分含量的比值为(0.2至5)：1；可选为(0.5至2)：1。
  13. 根据权利要求1至12中任一项所述的隔离膜，其中，
    所述聚合物层的涂布克重为0.5mg/1540.25mm2至5mg/1540.25mm2。
  14. 一种电池单体，包括如权利要求1至13中任一项所述的隔离膜。
  15. 一种电池，包括根据权利要求1至14中任一项所述的电池单体。
  16. 一种用电装置，包括根据权利要求15所述的电池。
PCT/CN2023/088796 2023-04-17 2023-04-17 隔离膜、电池单体、电池和用电装置 WO2024216468A1 (zh)

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