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WO2024027551A1 - 电化学装置及包含该电化学装置的电子装置 - Google Patents

电化学装置及包含该电化学装置的电子装置 Download PDF

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Publication number
WO2024027551A1
WO2024027551A1 PCT/CN2023/109567 CN2023109567W WO2024027551A1 WO 2024027551 A1 WO2024027551 A1 WO 2024027551A1 CN 2023109567 W CN2023109567 W CN 2023109567W WO 2024027551 A1 WO2024027551 A1 WO 2024027551A1
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WIPO (PCT)
Prior art keywords
active material
negative electrode
electrochemical device
negative
current collector
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PCT/CN2023/109567
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English (en)
French (fr)
Inventor
董佳丽
胡茜
Original Assignee
宁德新能源科技有限公司
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Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to EP23849259.9A priority Critical patent/EP4394969A1/en
Publication of WO2024027551A1 publication Critical patent/WO2024027551A1/zh
Priority to US18/620,161 priority patent/US20240274787A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • 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 electrochemical technology, and in particular, to an electrochemical device and an electronic device including the electrochemical device.
  • Secondary batteries such as lithium-ion batteries, are widely used in electric vehicles, outdoor equipment, solar equipment and other fields due to their high energy density and long cycle life. With the rapid development of the above-mentioned fields, the market has put forward increasingly higher requirements for the long-term high temperature resistance performance of lithium-ion batteries.
  • the purpose of this application is to provide an electrochemical device and an electronic device including the electrochemical device, so as to improve the high-temperature storage performance of the electrochemical device.
  • a lithium ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to lithium ion batteries.
  • the specific technical solutions are as follows:
  • a first aspect of the present application provides an electrochemical device, which includes a negative electrode piece.
  • the negative electrode piece 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.
  • the negative electrode active material layer is disposed on at least one surface of the negative electrode current collector.
  • the material layer includes anode active material; the length L of the anode current collector and the width W of the anode current collector satisfy: 8 ⁇ L/W ⁇ 40, 40mm ⁇ W ⁇ 145mm; preferably, 18 ⁇ L/W ⁇ 40 ;
  • the R value of the negative active material is 0.1 to 0.4, preferably 0.15 to 0.30; the R value is within any area of 100 ⁇ m ⁇ 100 ⁇ m on the negative active material layer, and the negative active material particles are made of The average value of the peak intensity ratio I(D)/I(G) of the D peak and G peak of the Raman test; the D peak is the displacement range of 1300cm -1 to 1400cm in the Raman spectrum of the negative active material particles -1 peak, and the G peak is a peak in the Raman spectrum of the negative electrode active material particles with a displacement range from 1530 cm -1 to 1630 cm -1 .
  • the electrochemical device has an impedance of 30 m ⁇ to 60 m ⁇ . By regulating the impedance within the above range, the electrochemical device is placed in a more stable system. When the electrochemical device is stored at high temperatures, the phenomenon of gas production due to the reaction of the electrolyte is alleviated, thereby reducing the risk of expansion of the electrochemical device and improving High temperature storage performance of electrochemical devices.
  • the electrical conductivity ⁇ of the negative electrode plate satisfies: 15S/cm ⁇ 35S/cm, preferably, 25S/cm ⁇ 30S/cm.
  • the areal density of the negative active material layer is 0.05 mg/mm 2 to 0.11 mg/mm 2 .
  • the negative active material layer has a compacted density of 1.6 to 1.8 g/cm 3 .
  • the energy density of the electrochemical device can be increased while also improving the high-temperature storage performance of the electrochemical device.
  • the lattice index OI of the negative active material satisfies: 8 ⁇ OI ⁇ 20.
  • the electrochemical device includes an electrolyte, and the electrolyte includes ethylene carbonate (also known as ethylene carbonate, abbreviated as EC); based on the quality of the electrolyte, the carbonic acid
  • ethylene carbonate also known as ethylene carbonate, abbreviated as EC
  • the mass percentage of ethylene is 8% to 30%, preferably 15% to 25%.
  • the electrolyte includes a lithium salt
  • the lithium salt includes LiPF 6 , lithium bisfluorosulfonyl imide (LiFSI) or lithium bistrifluoromethanesulfonyl imide (LiTFSI).
  • LiPF 6 lithium bisfluorosulfonyl imide
  • LiTFSI lithium bistrifluoromethanesulfonyl imide
  • At least one of; the concentration of the lithium salt in the electrolyte is 0.9 mol/L to 1.5 mol/L.
  • a second aspect of the present application provides an electronic device, which includes the electrochemical device according to any of the preceding embodiments.
  • the present application provides an electrochemical device and an electronic device including the electrochemical device, wherein the electrochemical device includes a negative electrode piece, and the negative electrode piece includes a negative electrode current collector and is disposed on at least one surface of the negative electrode current collector.
  • the negative active material layer on the negative active material layer includes the negative active material; the length L of the negative current collector and the width W of the negative current collector satisfy: 8 ⁇ L/W ⁇ 40, 40mm ⁇ W ⁇ 145mm ;
  • the R value of the negative active material is 0.1 to 0.4; the R value is the D peak of the negative active material particles measured by Raman in any area with a size of 100 ⁇ m ⁇ 100 ⁇ m on the negative active material layer
  • the G peak is a peak in the Raman spectrum of the negative active material particles with
  • Figure 1 is a negative electrode current collector in one embodiment of the present application
  • Figure 2 is a Raman spectrum chart of the negative active material of Examples 1-4.
  • a lithium ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to lithium ion batteries.
  • the specific technical solutions are as follows:
  • a first aspect of the present application provides an electrochemical device, which includes a negative electrode piece.
  • the negative electrode piece 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.
  • the negative electrode active material layer includes a negative electrode active material.
  • the length L of the negative electrode current collector 10 and the width W of the negative electrode current collector 10 satisfy: 8 ⁇ L/W ⁇ 40, 40mm ⁇ W ⁇ 145mm; preferably, 18 ⁇ L/W ⁇ 40; negative electrode
  • the R value of the active material is 0.1 to 0.4, preferably 0.15 to 0.30; the R value is the negative active material in any area with a size of 100 ⁇ m ⁇ 100 ⁇ m on the negative active material layer.
  • the peak of 1 , the G peak is a peak in the Raman spectrum of the negative electrode active material particles with a displacement ranging from 1530 cm -1 to 1630 cm -1 .
  • the value of L/W can be 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40 or any value between any two of the above ranges.
  • W can be 40mm, 45.8mm, 50mm, 60mm, 66.4mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 145mm or any value between any two of the above numerical ranges.
  • the value of L/W is too small (for example, less than 8), the width W of the negative electrode piece is larger; when the value of L/W is too large (for example, greater than 40), the length L of the negative electrode piece is larger.
  • a larger width W of the negative electrode piece or a larger length L of the negative electrode piece will affect the initial impedance of the electrochemical device, causing the initial impedance to be outside a reasonable range, causing the system stability of the electrochemical device to be reduced, and the electrochemical During the charge and discharge cycle of the device, the impedance increases sharply, thereby increasing the thickness expansion rate of the electrochemical device.
  • the length L of the negative electrode current collector and the width W of the negative electrode current collector are more coordinated, so that the initial impedance of the electrochemical device is within a reasonable range, and the system stability of the electrochemical device is relatively stable.
  • the impedance of the electrochemical device increases slowly during the charge and discharge cycle, causing the thickness expansion rate of the electrochemical device to decrease.
  • the system stability of the electrochemical device is further improved.
  • the impedance increases more slowly, further reducing the thickness expansion rate of the electrochemical device. .
  • the R value can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 or any value between any two of the above numerical ranges.
  • the R value represents the crystallinity of the surface of the negative active material.
  • the R value is too small (for example, less than 0.1), and the kinetics of the negative active material is poor, resulting in high initial impedance.
  • the impedance continues to increase after high-temperature storage, ultimately affecting the system stability of the electrochemical device; the R value is too large (for example, greater than 0.4) , the surface of the negative active material is too active, and the surface reaction is violent, which is not conducive to long-term high-temperature storage of electrochemical devices.
  • Controlling the R value within the range of this application shows that the surface crystallinity of the negative active material is low and the dynamic properties of the negative active material are better. As a result, the relative impedance of the electrochemical device is still low after long-term half-charge storage at high temperatures above 80°C, and the dynamic performance of the electrochemical device is better. The lithium precipitation phenomenon after charging of the electrochemical device is suppressed and alleviated.
  • the kinetic performance of the electrochemical device will be better after long-term half-charge storage at high temperatures above 80°C. The lithium precipitation phenomenon after charging of the electrochemical device is further suppressed and alleviated.
  • the R value can be controlled by selecting different types of negative active materials. This application does not place special restrictions on this, as long as the R value is controlled within the scope of this application.
  • the ratio L/W of the length L to the width W of the negative electrode current collector is consistent with the ratio of the length L to the width W of the negative electrode current collector.
  • the synergistic effect between the R values of the active materials effectively improves the high-temperature storage performance of the electrochemical device.
  • the high-temperature storage performance of the electrochemical device can be further effectively improved.
  • the negative electrode current collector refers to one or both surfaces of the two surfaces along the thickness direction of the negative electrode current collector itself.
  • the "surface” can be the entire area of the negative electrode current collector, or it can be a part of the area of the negative electrode current collector.
  • the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, titanium foil, nickel foam or copper foam, etc.
  • the thickness of the negative electrode current collector is 6 ⁇ m to 10 ⁇ m.
  • the electrochemical device has an impedance of 30 m ⁇ to 60 m ⁇ .
  • the impedance may be 30m ⁇ , 35m ⁇ , 40m ⁇ , 45m ⁇ , 50m ⁇ , 55m ⁇ , 60m ⁇ , or any value between any two of the above numerical ranges. If the impedance is too small (for example, less than 30m ⁇ ) or too large (for example, more than 60m ⁇ ), the stability of the electrochemical device system will decrease. During the charging and discharging process of the electrochemical device, the increase in impedance will increase, which will affect the high temperature of the electrochemical device. Storage performance. By regulating the impedance within the above range, the electrochemical device is placed in a more stable system.
  • the electrical conductivity ⁇ of the negative electrode plate satisfies: 15S/cm ⁇ 35S/cm, preferably, 25S/cm ⁇ 30S/cm.
  • the conductivity ⁇ of the negative electrode piece can be 15 S/cm, 25 S/cm, 28 S/cm, 30 S/cm, 35 S/cm, or any value between any two of the above numerical ranges.
  • the current density at the interface between the negative electrode piece and the electrolyte can be further effectively controlled, thereby effectively alleviating the lithium precipitation phenomenon of the negative electrode piece and further improving the performance of the electrochemical device. High temperature storage performance.
  • the conductivity ⁇ of the negative electrode piece can be controlled by adjusting the type of negative electrode active material, the compaction density of the negative electrode active material layer, etc. This application does not impose any special restrictions on this, as long as the conductivity of the negative electrode piece is The rate ⁇ can be controlled within the scope of this application.
  • the areal density of the negative active material layer is 0.05 mg/mm 2 to 0.11 mg/mm 2 .
  • the areal density of the negative active material layer may be 0.05 mg/mm 2 , 0.07 mg/mm 2 , 0.09 mg/mm 2 , or 0.11 mg/mm 2 Or any value between any two numerical ranges mentioned above. If the area density of the negative active material layer is too small (for example, less than 0.05 mg/mm 2 ), it will easily affect the adhesion between the negative active material layer and the negative current collector.
  • the area density of the negative active material layer is too large (for example, greater than 0.11 mg/mm 2 ), it will easily affect the transmission of lithium ions, causing lithium precipitation in the electrochemical device, and affecting the high-temperature storage performance of the electrochemical device.
  • the areal density of the negative active material layer is more conducive to improving the high-temperature storage performance of the electrochemical device.
  • the negative active material layer has a compacted density of 1.6 to 1.8 g/cm 3 .
  • the compacted density of the negative active material layer may be 1.6g/cm 3 , 1.65g/cm 3 , 1.7g/cm 3 , 1.75g/cm 3 , 1.8g/cm 3 or any two of the above numerical ranges. any value.
  • the compaction density of the negative active material layer can be adjusted by adjusting the roll gap size of the cold press and the preset pressure value. This application does not impose special restrictions on this, as long as the negative active material layer is The compaction density can be controlled within the scope of this application.
  • the lattice index OI of the negative active material when the state of charge of the electrochemical device is 0%, the lattice index OI of the negative active material satisfies: 8 ⁇ OI ⁇ 20.
  • the lattice index OI of the negative active material may be 8, 10, 12, 14, 16, 18, 20, or any value between any two of the above numerical ranges.
  • the negative active material may include, but is not limited to, at least one of artificial graphite, natural graphite, or hard carbon.
  • This application has no special restrictions on the preparation method of the negative active material, as long as the purpose of this application can be achieved.
  • the electrochemical device includes an electrolyte, and the electrolyte includes EC; based on the mass of the electrolyte, the mass percentage of EC is 8% to 30%, preferably 15% to 25%.
  • the mass percentage of EC can be 8%, 12%, 15%, 17%, 20%, 25%, 30% or any value between any two of the above numerical ranges. If the mass percentage of EC is too low (for example, less than 8%), it is difficult to passivate the interface between the negative electrode plate and the electrolyte.
  • the mass percentage of EC is too high (for example, higher than 30%), the viscosity of the electrolyte will increase at low temperatures, gas generation will easily occur at high voltages, and the expansion rate of the electrochemical device will increase.
  • it is more conducive to passivating the interface between the negative electrode plate and the electrolyte, so that the lithium evolution phenomenon can be alleviated, and it is also more conducive to suppressing the gas production phenomenon of the electrolyte, thereby being more conducive to Improve the high-temperature storage performance of electrochemical devices.
  • the electrolyte solution includes a lithium salt
  • the lithium salt includes at least one of LiPF 6 , LiFSI or LiTFSI
  • the concentration of the lithium salt in the electrolyte solution is 0.9 mol/L to 1.5 mol/L.
  • the concentration of lithium salt in the electrolyte can be 0.9 mol/L, 1.0 mol/L, 1.1 mol/L, 1.3 mol/L, 1.5 mol/L or any value between any two of the above numerical ranges.
  • Lithium salts have poor thermal stability in high-temperature environments and are easily decomposed, causing an increase in the acidity of the electrolyte.
  • lithium salts By selecting the above types of lithium salts and regulating the concentration of lithium salts in the electrolyte within the above range, it is more conducive to reducing the acidity of the electrolyte.
  • the increase can alleviate the impact of the dissolution of transition metals in the cathode active material, thereby improving the high-temperature storage performance of the electrochemical device.
  • the electrolyte solution of the present application includes non-aqueous solvents.
  • the non-aqueous solvent may include at least one of a carbonate compound, a carboxylate compound, an ether compound, or other organic solvents.
  • the above-mentioned carbonate compound may include, but is not limited to, at least one of a chain carbonate compound, a cyclic carbonate compound or a fluorinated carbonate compound.
  • the above-mentioned chain carbonate compounds may include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), and ethylpropyl carbonate (EPC). Or at least one of ethyl methyl carbonate (EMC).
  • the above-mentioned cyclic carbonate compound may include, but is not limited to, at least one of propylene carbonate (PC), butylene carbonate (BC) or vinyl ethylene carbonate (VEC).
  • the above-mentioned fluorocarbonate compounds may include, but are not limited to, fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-difluoroethylene carbonate. Trifluoroethylene, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, At least one of 2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-difluoroethylene carbonate 1,1,2-difluoroethylene carbonate
  • Trifluoroethylene 1,1,2,2-tetrafluoroethylene carbonate
  • 1-fluoro-2-methylethylene carbonate 1-fluoro-1-methylethylene carbonate
  • the above-mentioned carboxylic acid ester compound may include, but is not limited to, at least one of ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate or propyl propionate.
  • the above-mentioned ether compounds may include but are not limited to dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxy At least one of methylmethoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include, but are not limited to, dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2- At least one of pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate or phosphate.
  • the mass percentage of the above-mentioned non-aqueous solvent is 5% to 70%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% , 50%, 55%, 60%, 65%, 70% or any value between any two of the above numerical ranges.
  • the electrochemical device of this application includes a positive electrode piece.
  • the positive electrode sheet includes a positive current collector and a positive active material layer.
  • the positive electrode current collector may include aluminum foil, aluminum alloy foil, or the like.
  • the cathode active material layer of the present application contains a cathode active material. This application has no particular limitation on the type of positive electrode active material, as long as it can achieve the purpose of this application.
  • the positive active material may include lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO 2 ), lithium manganate, lithium iron manganese phosphate, or lithium titanate. at least one of them.
  • the cathode active material may also contain non-metal elements.
  • the non-metal elements include at least one of fluorine, phosphorus, boron, chlorine, silicon, sulfur, etc. These elements can further improve the stability of the cathode active material.
  • the thickness of the positive electrode current collector is 5 ⁇ m to 20 ⁇ m, preferably 6 ⁇ m to 18 ⁇ m.
  • the thickness of the single-sided positive active material layer is 30 ⁇ m to 120 ⁇ m.
  • the cathode active material layer may be disposed on one surface in the thickness direction of the cathode current collector, or may be disposed on both surfaces in the thickness direction of the cathode current collector.
  • the "surface" here can be the entire area of the positive electrode current collector, or it can be a partial area of the positive electrode current collector.
  • the positive electrode plate may further include a conductive layer located between the positive electrode current collector and the positive electrode active material layer.
  • the composition of the conductive layer is not particularly limited and may be a conductive layer commonly used in this field.
  • the preparation method of the positive active material includes the following steps:
  • step (3) Mechanical crushing and airflow pulverization: The primary sintered material obtained in step (3) is cooled and then subjected to mechanical crushing, airflow pulverization and classification;
  • Secondary sintering coating Mix the primary sintering material crushed and classified in step (4) and the coating additive at a mass ratio of (90-110):0.5, then mix them evenly in a high mixer, and install After being put into the sagger, it is placed in the kiln and calcined in an air atmosphere for 5 to 7 hours. The obtained material is then subjected to mechanical powder classification, demagnetization, and sieving to obtain the positive active material.
  • This application has no special restrictions on the types of the above-mentioned coating additives, as long as the purpose of this application can be achieved.
  • the electrochemical device of the present application includes a separator, and the present application has no special restrictions on the separator, as long as it can achieve the purpose of the present application.
  • the separator may include a substrate layer and a surface treatment layer.
  • the base material layer can be a non-woven fabric, film or composite film with a porous structure.
  • the material of the base material layer can include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide. kind.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • a surface treatment layer is provided on at least one surface of the base material layer.
  • the surface treatment layer may be a polymer layer or an inorganic layer, or may be a layer formed by mixing a polymer and an inorganic substance.
  • the inorganic layer includes inorganic particles and a binder.
  • the inorganic particles are not particularly limited and may include, for example, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, and zinc oxide. , at least one of calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the binder is not particularly limited, and may include, for example, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, and polyvinylpyrrolidone. , at least one of polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the polymer material includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( At least one of vinylidene fluoride-hexafluoropropylene), etc.
  • the electrochemical device of the present application is not particularly limited and may include any device that undergoes electrochemical reactions.
  • the electrochemical device may include, but is not limited to: a lithium metal secondary battery, a lithium ion battery, a sodium ion secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, and the like.
  • the preparation process of the electrochemical device is well known to those skilled in the art, and the present application is not particularly limited. For example, it may include but is not limited to the following steps: stack the positive electrode sheets, separators, and negative electrode sheets in order, and stack the positive electrode sheets as needed.
  • the winding, folding and other operations obtain an electrode assembly with a wound structure.
  • the electrode assembly is placed into the packaging shell and the electrolyte is injected into the packaging.
  • a second aspect of the present application provides an electronic device, which includes the electrochemical device according to any of the preceding embodiments. Therefore, the beneficial effects of the electrochemical device described in any of the preceding embodiments can be obtained.
  • the electronic device of the present application is not particularly limited, and may include but is not limited to the following categories: notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, head-mounted Stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles , bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • D peak the displacement range is 1300cm -1 to 1400cm -1 , caused by the symmetric stretching vibration radial breathing mode of sp2 carbon atoms in the aromatic ring (structural defect);
  • G peak the displacement range is 1530cm -1 to 1630cm -1 , caused by It is caused by the stretching vibration between sp2 carbon atoms, which corresponds to the vibration of the E2g optical phonon in the center of the Brillouin zone (in-plane vibration of the carbon atom).
  • the DCR measured for each lithium-ion battery after the fifth discharge step was taken, and the corresponding average value was calculated as the DCR measured for each embodiment and comparative example of the present application (as shown in Table 1 to Table 3).
  • the DCR mentioned in this application refers to the average DCR measured after the fifth discharge step of each lithium-ion battery.
  • R is the resistance of the negative electrode piece
  • ⁇ is the resistivity of the negative electrode piece
  • S is the test area of the negative electrode piece.
  • m is the mass of the negative active material layer, unit: g;
  • Ar is the area of the negative active material layer, unit: mm 2 .
  • Ma is the mass of the negative active material layer, unit: g; Va is the volume of the negative active material layer, unit: cm 3 , where the volume Va is the area Sa of the negative active material layer and the thickness of the negative active material layer. product.
  • OI value C(004)/C(110).
  • the passing number refers to the number of lithium-ion batteries whose thickness expansion rate is less than or equal to 12% among the 10 lithium-ion batteries tested in each example or comparative example.
  • the concentration of LiPF 6 in the electrolyte is 1.0 mol/L; based on the mass of the electrolyte, the mass percentage of EC is 8%, the mass percentage of fluoroethylene carbonate is 3%, and the mass percentage of adiponitrile is The mass percentage is 3%; the rest is PC and DEC, and the mass ratio of PC and DEC is 1:2.
  • the negative electrode piece with a specification of 87.6mm ⁇ 700.8mm (length L is 700.8mm, width W is 87.6mm) is obtained.
  • the lattice index OI of the negative active material is 18, the R value is 0.15, the areal density of the negative active material layer is 0.08mg/mm 2 , the compacted density is 1.7g/cm 3 , and the conductivity ⁇ of the negative electrode sheet is 15S/cm.
  • Sodium oxide is prepared into an alkali solution with a molar concentration of 4 mol/L, and ammonia water with a concentration of 4 mol/L is used as a complexing agent; all prepared solutions must be filtered first to remove solid impurities before entering the next step; mix the filtered
  • the salt solution, alkali solution, and complexing agent were added to the reaction kettle at a flow rate of 30L/h. The stirring rate of the reaction kettle was controlled to 30r ⁇ min -1 .
  • the temperature of the reaction slurry was normal temperature and the pH was 11.5 to neutralize the salt and alkali. and react to generate ternary precursor crystal nuclei and gradually grow up.
  • the reaction slurry is filtered, washed, and dried to obtain a ternary precursor;
  • step (3) Mechanical crushing and airflow pulverization: The primary sintered material obtained in step (3) is cooled and then subjected to mechanical crushing, airflow pulverization and classification;
  • Secondary sintering coating Mix the primary sintering material crushed and classified in step (4) with the coating additive alumina at a mass ratio of 100:0.5, mix them evenly in a high mixer, and put them into the box The pot is placed in a kiln, and after calcining in an air atmosphere for 6 hours, the obtained material is subjected to mechanical powder classification, demagnetization, and sieving to obtain the cathode active material.
  • a positive electrode slurry is obtained, in which the solid content of the positive electrode slurry is 70wt%.
  • the positive electrode slurry is evenly coated on one surface of the positive electrode current collector aluminum foil with a thickness of 12 ⁇ m, and the aluminum foil is dried at 120°C to obtain a positive electrode sheet coated with a positive electrode active material layer on one side.
  • a porous polyethylene film with a thickness of 7 ⁇ m (provided by Celgard) was used.
  • the positive electrode piece, separator, and negative electrode piece prepared above are stacked in order, so that the separator is between the positive electrode piece and the negative electrode piece to play an isolation role, and the electrode assembly is obtained by winding.
  • the electrode assembly is placed in an aluminum-plastic film packaging bag, dried and then injected with electrolyte. After vacuum packaging, standing, formation, degassing, trimming and other processes, a lithium-ion battery is obtained.
  • Example 1-1 Except for adjusting relevant preparation parameters according to Table 1, the rest is the same as Example 1-1.
  • Example 1-1 Except for adjusting relevant preparation parameters according to Table 2, the rest is the same as Example 1-1.
  • Example 1-1 Except for adjusting relevant preparation parameters according to Table 3, the rest is the same as Example 1-1.
  • Example 1-1 Except for adjusting relevant preparation parameters according to Table 1, the rest is the same as Example 1-1.
  • Examples 1-1 to 1-9 and Comparative Examples 3 to 6 that both the L/W value and the R value are within the scope of the present application (such as Examples 1-1 to 6).
  • Examples 1-9) compared to lithium-ion batteries whose L/W values or R values are not within the scope of the present application (such as Comparative Examples 3 to 6), have smaller thickness expansion rates and higher pass rates. number, indicating that lithium-ion batteries have better high-temperature storage performance.
  • Figure 2 shows the Raman spectrum of the negative active material of Examples 1-4. As shown in Figure 2, the figure has a D peak with a displacement range from 1300 cm -1 to 1400 cm -1 and a displacement range from 1530 cm -1 to The G peak at 1630cm -1 has an R value of 0.30.
  • the mass percentage of EC in the electrolyte usually affects the high-temperature storage performance of lithium-ion batteries. It can be seen from Example 1-1, Example 2-1 to Example 2-5 that a lithium-ion battery with a mass percentage of EC in the electrolyte within the scope of the present application has a larger DCR and has Lower thickness expansion rate and higher number of passes means good high-temperature storage performance.
  • lithium salt often affects the high-temperature storage performance of lithium-ion batteries. It can be seen from Examples 2-4, 2-6 and 2-7 that lithium ion batteries with lithium salt types within the scope of the present application have larger DCR and lower thickness expansion. rate and high number of passes, that is, it has good high-temperature storage performance.
  • the concentration of lithium salt in the electrolyte often affects the high-temperature storage performance of lithium-ion batteries. It can be seen from Examples 2-4 and 2-8 that lithium-ion batteries with a concentration of lithium salt in the electrolyte within the scope of the present application have a larger DCR and a lower thickness expansion rate and A higher number of passes means good high-temperature storage performance.
  • the conductivity ⁇ of the negative electrode plate usually affects the high-temperature storage performance of lithium-ion batteries. It can be seen from Example 1-1, Example 3-1 to Example 3-3 that a lithium-ion battery with a negative electrode plate with a conductivity ⁇ within the scope of the present application has a larger DCR and a lower The thickness expansion rate and high number of passes mean it has good high-temperature storage performance.
  • the areal density of the negative active material layer usually affects the high-temperature storage performance of lithium-ion batteries. It can be seen from Example 1-1, Example 3-4 and Example 3-5 that the area density of the negative active material layer is within the range of the lithium ion battery of the present application.
  • the pool has a large DCR, a low thickness expansion rate and a high number of passes, that is, it has good high-temperature storage performance.
  • the compaction density of the negative active material layer usually affects the high-temperature storage performance of lithium-ion batteries. It can be seen from Example 1-1, Example 3-6 and Example 3-7 that a lithium-ion battery with a compacted density of the negative active material layer within the scope of the present application has a larger DCR and a smaller Low thickness expansion rate and high number of passes mean it has good high-temperature storage performance.

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Abstract

一种电化学装置及包含该电化学装置的电子装置，其中，该电化学装置包括负极极片，负极极片包括负极集流体以及设置于负极集流体至少一个表面上的负极活性材料层，负极活性材料层包括负极活性材料；负极集流体的长度L与负极集流体的宽度W满足：8≤L/W≤40，40mm≤W≤145mm；负极活性材料的R值为0.1至0.4。将负极集流体的长度L与宽度W的比值、以及负极活性材料的R值同时调控在上述范围内，使电化学装置的高温存储性能得到有效提升。

Description

电化学装置及包含该电化学装置的电子装置
本申请要求于2022年8月1日提交中国专利局、申请号为202210914963.7、发明名称为“电化学装置及包含该电化学装置的电子装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电化学技术领域，特别是涉及一种电化学装置及包含该电化学装置的电子装置。
背景技术
二次电池，如锂离子电池，因其高能量密度、长循环寿命等优点，被广泛应用于电动汽车、户外设备、太阳能设备等领域。随着上述领域的迅速发展，市场对锂离子电池的长期耐高温性能提出了越来越高的要求。
但是现有的锂离子电池在80℃以上的高温下连续存储时，其存储性能受到较大影响。因此，如何提高电化学装置的高温存储性能，成为本领域技术人员亟待解决的技术问题。
发明内容
本申请的目的在于提供一种电化学装置及包含该电化学装置的电子装置，以提升电化学装置的高温存储性能。
需要说明的是，本申请的发明内容中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。具体技术方案如下：
本申请第一方面提供了一种电化学装置，其包括负极极片，所述负极极片包括负极集流体以及设置于所述负极集流体至少一个表面上的负极活性材料层，所述负极活性材料层包括负极活性材料；所述负极集流体的长度L与所述负极集流体的宽度W满足：8≤L/W≤40，40mm≤W≤145mm；优选地，18≤L/W≤40；所述负极活性材料的R值为0.1至0.4，优选为0.15至0.30；所述R值为所述负极活性材料层上尺寸为100μm×100μm的任一区域内，所述负极活性材料颗粒采用拉曼测试的D峰与G峰的峰强比值I(D)/I(G)的平均值；所述D峰为所述负极活性材料颗粒的拉曼光谱中位移范围为1300cm-1至1400cm-1的峰，所述G峰为负极活性材料颗粒的拉曼光谱中位移范围为1530cm-1至1630cm-1的峰。通过将负极集流体的长度L与宽度W的比值、以及负极活性材料的R值同时调控在上述范围内，使电化学装置的 高温存储性能得到有效提升。
在本申请的一种实施方案中，所述电化学装置的阻抗为30mΩ至60mΩ。通过将阻抗调控在上述范围内，使电化学装置处于较稳定的体系中，电化学装置在高温下存储时，电解液反应产气的现象得以缓解，从而降低电化学装置发生膨胀的风险，提升电化学装置的高温存储性能。
在本申请的一种实施方案中，所述负极极片的电导率σ满足：15S/cm≤σ≤35S/cm，优选地，25S/cm≤σ≤30S/cm。通过将负极极片的电导率σ调控在上述范围内，能够有效控制负极极片与电解液界面的电流密度，从而缓解负极极片的析锂现象，提升电化学装置的高温存储性能。
在本申请的一种实施方案中，所述负极活性材料层的面密度为0.05mg/mm2至0.11mg/mm2。通过将负极活性材料层的面密度调控在上述范围内，更利于提升电化学装置的高温存储性能。
在本申请的一种实施方案中，所述负极活性材料层的压实密度为1.6g/cm3至1.8g/cm3。通过将负极活性材料层的压实密度调控在上述范围内，能够在提高电化学装置能量密度的同时，提升电化学装置的高温存储性能。
在本申请的一种实施方案中，所述电化学装置的荷电状态(SOC)为0％时，所述负极活性材料的晶格指数OI满足：8≤OI≤20。通过将负极活性材料的晶格指数OI调控在上述范围内，从而更利于提升电化学装置的高温存储性能。
在本申请的一种实施方案中，所述电化学装置包括电解液，所述电解液包括碳酸亚乙酯(也称碳酸乙烯酯，简写EC)；基于所述电解液的质量，所述碳酸亚乙酯的质量百分含量为8％至30％，优选为15％至25％。通过将EC的质量百分含量调控在本申请范围内，更利于钝化负极极片与电解液的界面，使得析锂现象得以缓解，也更利于抑制电解液的产气现象，从而更利于提升电化学装置的高温存储性能。
在本申请的一种实施方案中，所述电解液包括锂盐，所述锂盐包括LiPF6、双氟磺酰亚胺锂(LiFSI)或双三氟甲烷磺酰亚胺锂(LiTFSI)中的至少一种；所述锂盐在所述电解液中的浓度为0.9mol/L至1.5mol/L。通过选用上述种类的锂盐，且将锂盐在电解液中的浓度调控在上述范围内，更有利于降低电解液酸度的上升，缓解正极活性材料中过渡金属溶出带来的影响，从而提升电化学装置的高温存储性能。
本申请第二方面提供了一种电子装置，其包括前述任一实施方案所述的电化学装置。
本申请提供了一种电化学装置及包含该电化学装置的电子装置，其中，该电化学装置包括负极极片，所述负极极片包括负极集流体以及设置于所述负极集流体至少一个表面上的负极活性材料层，所述负极活性材料层包括负极活性材料；所述负极集流体的长度L与所述负极集流体的宽度W满足：8≤L/W≤40，40mm≤W≤145mm；所述负极活性材料的R值为0.1至0.4；所述R值为所述负极活性材料层上尺寸为100μm×100μm的任一区域内，所述负极活性材料颗粒采用拉曼测试的D峰与G峰的峰强比值I(D)/I(G)的平均值；所述D峰为所述负极活性材料颗粒的拉曼光谱中位移范围为1300cm-1至1400cm-1的峰，所述G峰为负极活性材料颗粒的拉曼光谱中位移范围为1530cm-1至1630cm-1的峰。将负极集流体的长度L与宽度W的比值、以及负极活性材料的R值同时调控在上述范围内，使电化学装置的高温存储性能得到有效提升。
当然，实施本申请的任一产品或方法并不一定需要同时达到以上所述的所有优点。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中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，还可以根据这些附图获得其他的实施例。
图1为本申请一种实施方案中的负极集流体；
图2为实施例1-4的负极活性材料的拉曼光谱图。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照实施例并举附图，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。本领域普通技术人员基于本申请中的实施例所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。具体技术方案如下：
本申请第一方面提供了一种电化学装置，其包括负极极片，负极极片包括负极集流体以及设置于负极集流体至少一个表面上的负极活性材料层，负极活性材料层包括负极活性材料；如图1所示，负极集流体10的长度L与负极集流体10的宽度W满足：8≤L/W≤40，40mm≤W≤145mm；优选地，18≤L/W≤40；负极活性材料的R值为0.1至0.4，优选为0.15至0.30；R值为负极活性材料层上尺寸为100μm×100μm的任一区域内，负极活性材 料颗粒采用拉曼测试的D峰与G峰的峰强比值I(D)/I(G)的平均值；D峰为负极活性材料颗粒的拉曼光谱中位移范围为1300cm-1至1400cm-1的峰，G峰为负极活性材料颗粒的拉曼光谱中位移范围为1530cm-1至1630cm-1的峰。
例如，L/W的值可以为8、10、12、14、16、18、20、25、30、35、40或上述任两个数值范围间的任一数值。W可以为40mm、45.8mm、50mm、60mm、66.4mm、70mm、80mm、90mm、100mm、110mm、120mm、130mm、140mm、145mm或上述任两个数值范围间的任一数值。当L/W的值过小(例如小于8)时，负极极片的宽度W较大；当L/W的值过大(例如大于40)时，负极极片的长度L较大。负极极片的宽度W较大或负极极片的长度L较大，均会影响电化学装置的初始阻抗，导致初始阻抗处于合理的范围之外，使得电化学装置的体系稳定性降低，电化学装置在充放电循环过程中，阻抗急剧增大，从而增大电化学装置的厚度膨胀率。通过将L/W的值调控在本申请范围内，负极集流体的长度L和负极集流体的宽度W更协调，使得电化学装置的初始阻抗处于合理范围内，电化学装置的体系稳定性较高，电化学装置在充放电循环过程中，阻抗增加缓慢，使得电化学装置的厚度膨胀率减小。将L/W的值调控在本申请优选范围内，电化学装置的体系稳定性进一步提高，电化学装置在充放电循环过程中，阻抗增加更缓慢，使得电化学装置的厚度膨胀率进一步减小。
R值可以为0.1、0.15、0.2、0.25、0.3、0.35、0.4或上述任两个数值范围间的任一数值。R值表征负极活性材料表面的结晶度。R值过小(例如小于0.1)，负极活性材料动力学较差，导致初始阻抗高，高温存储后阻抗继续增大，最终影响电化学装置的体系稳定性；R值过大(例如大于0.4)，负极活性材料表面太活跃，表面反应剧烈，不利于电化学装置的长时间高温存储。将R值调控在本申请范围内，表明负极活性材料的表面结晶度较低，负极活性材料的动力学性能较好。使得电化学装置在80℃以上的高温下长期半充存储后，相对阻抗仍然较低，电化学装置的动力学性能较好。电化学装置充电后析锂现象得到抑制和缓解。将R值调控在本申请优选范围内，电化学装置在80℃以上的高温下长期半充存储后，电化学装置的动力学性能更好。电化学装置充电后析锂现象进一步得到抑制和缓解。
在本申请中，R值可以通过选用不同种类的负极活性材料等方式来调控，本申请对此不做特别限制，只要将R值调控在本申请范围内即可。
由此，通过将负极集流体的长度L与宽度W的比值L/W、以及负极活性材料的R值同时调控在上述范围内，负极集流体的长度L与宽度W的比值L/W与负极活性材料的R值之间产生协同作用，使电化学装置的高温存储性能得到有效提升。
将负极集流体的长度L与宽度W的比值L/W、和/或负极活性材料的R值同时调控在上述优选范围内，电化学装置的高温存储性能得到进一步有效提升。
在本申请中，“负极集流体至少一个表面”是指，沿负极集流体自身厚度方向的两个表面中的一个表面或两个表面。“表面”可以是负极集流体的全部区域，也可以是负极集流体的部分区域，本申请没有特别限制，本领域技术人员可以根据实际需要选择，只要能实现本申请目的即可。本申请对负极集流体的种类没有特别限制，只要能够实现本申请目的即可。例如，负极集流体可以包含铜箔、铜合金箔、镍箔、钛箔、泡沫镍或泡沫铜等。本申请对负极集流体的厚度没有特别限制，只要能够实现本申请目的即可。例如负极集流体的厚度为6μm至10μm。
在本申请的一种实施方案中，电化学装置的阻抗为30mΩ至60mΩ。例如，阻抗可以为30mΩ、35mΩ、40mΩ、45mΩ、50mΩ、55mΩ、60mΩ或上述任两个数值范围间的任一数值。阻抗过小(例如小于30mΩ)或过大(例如大于60mΩ)，电化学装置体系的稳定性有所下降，电化学装置充放电过程中，阻抗的增加幅度增大，将影响电化学装置的高温存储性能。通过将阻抗调控在上述范围内，使电化学装置处于较稳定的体系中，电化学装置在高温下存储时，电解液反应产气的现象得以缓解，从而降低电化学装置发生膨胀的风险，提升电化学装置的高温存储性能。需要说明，本申请中的“阻抗”应当理解为直流阻抗(DCR)。
在本申请的一种实施方案中，负极极片的电导率σ满足：15S/cm≤σ≤35S/cm，优选地，25S/cm≤σ≤30S/cm。例如，负极极片的电导率σ可以为15S/cm、25S/cm、28S/cm、30S/cm、35S/cm或上述任两个数值范围间的任一数值。通过将负极极片的电导率σ调控在上述范围内，能够有效控制负极极片与电解液之间界面的电流密度，从而缓解负极极片的析锂现象，提升电化学装置的高温存储性能。通过将负极极片的电导率σ调控在上述优选范围内，能够进一步有效控制负极极片与电解液之间界面的电流密度，从而有效缓解负极极片的析锂现象，进一步提升电化学装置的高温存储性能。
在本申请中，负极极片的电导率σ可以通过调节负极活性材料的种类、负极活性材料层的压实密度等方式来调控，本申请对此不做特别限制，只要将负极极片的电导率σ调控在本申请范围内即可。
在本申请的一种实施方案中，负极活性材料层的面密度为0.05mg/mm2至0.11mg/mm2。例如，负极活性材料层的面密度可以为0.05mg/mm2、0.07mg/mm2、0.09mg/mm2、0.11mg/mm2 或上述任两个数值范围间的任一数值。负极活性材料层的面密度过小(例如小于0.05mg/mm2)，易影响负极活性材料层与负极集流体之间的粘结性。负极活性材料层的面密度过大(例如大于0.11mg/mm2)，易影响锂离子的传输而导致电化学装置产生析锂现象，影响电化学装置的高温存储性能。通过将负极活性材料层的面密度调控在上述范围内，更利于提升电化学装置的高温存储性能。
在本申请的一种实施方案中，负极活性材料层的压实密度为1.6g/cm3至1.8g/cm3。例如，负极活性材料层的压实密度可以为1.6g/cm3、1.65g/cm3、1.7g/cm3、1.75g/cm3、1.8g/cm3或上述任两个数值范围间的任一数值。通过将负极活性材料层的压实密度调控在上述范围内，能够在提高电化学装置能量密度的同时，使负极活性材料层中留有充足的孔隙，缓解电化学装置充放电过程中负极活性材料的膨胀，从而降低电化学装置发生膨胀的风险，提升电化学装置的高温存储性能。
在本申请中，可以通过调整冷压机的辊缝缝隙大小和预设压力值等方式来调控负极活性材料层的压实密度，本申请对此不做特别限制，只要将负极活性材料层的压实密度调控在本申请范围内即可。
在本申请的一种实施方案中，电化学装置的荷电状态为0％时，负极活性材料的晶格指数OI满足：8≤OI≤20。例如，负极活性材料的晶格指数OI可以为8、10、12、14、16、18、20或上述任两个数值范围间的任一数值。通过将负极活性材料的晶格指数OI调控在上述范围内，能够让负极活性材料有较好动力学的同时也能保证负极活性材料的结构稳定性，从而更利于提升电化学装置的高温存储性能。
本申请对负极活性材料的种类没有特别限制，只要能够实现本申请目的即可。例如，负极活性材料可以包括但不限于人造石墨、天然石墨或硬碳中的至少一种。
本申请对负极活性材料的制备方法没有特别限制，只要能够实现本申请目的即可。
在本申请的一种实施方案中，电化学装置包括电解液，电解液包括EC；基于电解液的质量，EC的质量百分含量为8％至30％，优选为15％至25％。例如，EC的质量百分含量可以为8％、12％、15％、17％、20％、25％、30％或上述任两个数值范围间的任一数值。EC的质量百分含量过低(例如低于8％)，不易于钝化负极极片与电解液的界面。EC的质量百分含量过高(例如高于30％)，电解液在低温下粘度增大，在高电压下容易发生产气，增大电化学装置的膨胀率。通过将EC的质量百分含量调控在本申请范围内，更利于钝化负极极片与电解液的界面，使得析锂现象得以缓解，也更利于抑制电解液的产气现象，从而更利于 提升电化学装置的高温存储性能。通过将EC的质量百分含量调控在本申请优选范围内，更利于进一步钝化负极极片与电解液的界面，使得析锂现象得以进一步缓解，也更利于进一步抑制电解液的产气现象，从而更利于进一步提升电化学装置的高温存储性能。
在本申请的一种实施方案中，电解液包括锂盐，锂盐包括LiPF6、LiFSI或LiTFSI中的至少一种；锂盐在电解液中的浓度为0.9mol/L至1.5mol/L。例如，锂盐在电解液中的浓度可以为0.9mol/L、1.0mol/L、1.1mol/L、1.3mol/L、1.5mol/L或上述任两个数值范围间的任一数值。锂盐在高温环境下的热稳定性差，容易分解导致电解液酸度上升，通过选用上述种类的锂盐，且将锂盐在电解液中的浓度调控在上述范围内，更有利于降低电解液酸度的上升，缓解正极活性材料中过渡金属溶出带来的影响，从而提升电化学装置的高温存储性能。
本申请的电解液包括非水溶剂。本申请对非水溶剂没有特别限制，只要能够实现本申请目的即可。例如，非水溶剂可以包含碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(EMC)中的至少一种。上述环状碳酸酯化合物可以包括但不限于碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。上述氟代碳酸酯化合物可以包括但不限于氟代碳酸亚乙酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯或丙酸丙酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯或磷酸酯中的至少一种。基于电解液的质量，上述非水溶剂的质量百分含量为5％至70％，例如，5％、10％、15％、20％、25％、30％、35％、40％、45％、50％、55％、60％、65％、70％或上述任两个数值范围间的任一数值。
本申请的电化学装置包括正极极片，本申请对正极极片没有特别限制，只要能够实现 本申请目的即可。例如，正极极片包含正极集流体和正极活性材料层。本申请对正极集流体没有特别限制，只要能够实现本申请目的即可。例如，正极集流体可以包含铝箔或铝合金箔等。本申请的正极活性材料层包含正极活性材料。本申请对正极活性材料的种类没有特别限制，只要能够实现本申请目的即可。例如，正极活性材料可以包含锂镍钴锰氧、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂(LiCoO2)、锰酸锂、磷酸锰铁锂或钛酸锂等中的至少一种。在本申请中，正极活性材料还可以包含非金属元素，例如非金属元素包括氟、磷、硼、氯、硅、硫等中的至少一种，这些元素能进一步提高正极活性材料的稳定性。在本申请中，对正极集流体和正极活性材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为5μm至20μm，优选为6μm至18μm。单面正极活性材料层的厚度为30μm至120μm。在本申请中，正极活性材料层可以设置于正极集流体厚度方向上的一个表面上，也可以设置于正极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是正极集流体的全部区域，也可以是正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。任选地，正极极片还可以包含导电层，导电层位于正极集流体和正极活性材料层之间。导电层的组成没有特别限制，可以是本领域常用的导电层。
本申请对正极活性材料的制备方法没有特别限制，只要能实现本申请目的即可。例如，正极活性材料的制备方法包括以下步骤：
(1)前驱体：将硫酸镍(或氯化镍)、硫酸钴(或氯化钴)、硫酸锰(或氯化锰)按照n(Ni):n(Co):n(Mn)＝(0.4-0.6):(0.1-0.3):0.3配制成摩尔溶度1mol/L至3mol/L的混合盐溶液，氢氧化钠配制成摩尔浓度3mol/L至5mol/L的碱溶液，用浓度3mol/L至5mol/L的氨水作为络合剂；所有配制好的溶液要先经过过滤，去除固体杂质后才能进入下一个环节；将过滤后的盐溶液、碱溶液、络合剂以流量20L/h至40L/h加入到反应釜，控制反应釜的搅拌速率为20r·min-1至40r·min-1、反应浆料的温度为常温、pH为10至13，使盐、碱发生中和反应生成三元前驱体晶核并逐渐长大，当平均粒径达到2.5μm至4.5μm后，将反应浆料过滤、洗涤、干燥得到三元前驱体；
(2)一次混料：将锂源Li2CO3与前驱体按照(1.01-1.10):1的Li/M(M＝Ni、Co、Mn)摩尔比配料后置于高混机中加入到匣钵中进行下一步一次烧结工序；
(3)一次烧结：将步骤(2)中混合均匀的装入匣钵中的物料置于窑炉中先在空气气氛中以升温速率4℃/min至6℃/min缓慢升温至一次烧结温度680℃至720℃进行预烧，再在该一次烧结温度下的空气气氛煅烧11至13h得到一次烧结物料；
(4)机械破碎及气流粉碎：将步骤(3)中得到的一次烧结物料冷却后进行机械破碎、气流粉碎以及分级处理；
(5)二次烧结包覆：将步骤(4)中粉碎及分级处理后的一次烧结物料与包覆添加剂按(90-110):0.5的质量比混合后在高混机中混合均匀，装入匣钵后置于窑炉中，在空气气氛中煅烧5h至7h后，将获得物料经过机械制粉分级、除磁、筛粉获得正极活性材料。本申请对上述包覆添加剂的种类没有特别限制，只要能够实现本申请目的即可。
本申请的电化学装置包括隔膜，本申请对隔膜没有特别限制，只要能够实现本申请目的即可。例如，隔膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺等中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。例如，无机物层包括无机颗粒和粘结剂，无机颗粒没有特别限制，例如可以包括氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡等中的至少一种。粘结剂没有特别限制，例如可以包括聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯等中的至少一种。聚合物层中包含聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)等中的至少一种。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在一些实施方案中，电化学装置可以包括但不限于：锂金属二次电池、锂离子电池、钠离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池等。
电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极极片、隔膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装壳内，将电解液注入包 装壳并封口，得到电化学装置；或者，将正极极片、隔膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装壳内，将电解液注入包装壳并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装壳中，从而防止电化学装置内部的压力上升、过充放电。
本申请第二方面提供了一种电子装置，其包括前述任一实施方案所述的电化学装置。因此，能够获得前述任一实施方案所述的电化学装置的有益效果。
本申请的电子装置没有特别限制，其可以包括但不限于以下种类：笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。
测试方法和设备：
R值的测试：
在负极活性材料层上选取一个大小为100μm×100μm的面积，利用激光显微共聚焦拉曼光谱仪(Raman，HR Evolution，HORIBA科学仪器事业部)扫描该面积内的负极活性材料颗粒，得到该面积范围内所有负极活性材料颗粒的D峰、G峰，采用LabSpec软件对数据进行处理得到每一个负极活性材料颗粒的D峰、G峰的峰强，分别为I(D)和I(G)，拉曼光谱仪的激光波长可处于532nm至785nm的范围内。R值＝I(D)/I(G)的值，为该范围内测得的所有负极活性材料颗粒的I(D)和I(G)比值的平均值。
D峰：位移范围为1300cm-1至1400cm-1，由芳香环中sp2碳原子的对称伸缩振动径向呼吸模式引起(结构缺陷)；G峰：位移范围为1530cm-1至1630cm-1，由sp2碳原子间的拉伸振动引起，它对应布里渊区中心的E2g光学声子的振动(碳原子面内振动)。
DCR的测试：
取5颗各实施例和对比例制得的锂离子电池，将各锂离子电池置于25℃的恒温箱中搁置5分钟，以1C的倍率恒流充电至4.2V，再恒压充电至电流小于等于0.05C，静置30分 钟，以0.1C的电流放电10秒，记录对应电压值U1，再以1C的电流放电360秒，记录对应电压值U2，重复上述放电步骤直至电池的电压小于3.0V。“1C”是在1小时内将各锂离子电池容量完全放完的电流值。
对各锂离子电池每进行上述一次放电步骤(即分别以0.1C的电流放电10秒和以1C的电流放电360秒各1次)后，按如下公式计算得出锂离子电池在25℃下相应放电步骤后的直流电阻DCR：R＝(U1－U2)/(1C－0.1C)，单位为毫欧姆mΩ。取各锂离子电池在第5次放电步骤后测得的DCR，并求相应的平均值后，作为本申请各实施例和对比例测得的DCR(如表1-表3)。
除非有特别说明，本申请所述的DCR指的是各锂离子电池在第5次放电步骤后测得的DCR的平均值。
负极极片的电导率σ的测试：
负极极片电导率σ通过极片电阻仪测试，通过公式R＝ρ×l/S，而σ＝1/ρ，所以σ＝l/(R×S)。式中，R是负极极片的电阻，ρ是负极极片的电阻率，S是负极极片的测试面积。
负极活性材料层的面密度的测试：
负极活性材料层的面密度Q通过公式：Q＝1540.25m/Ar计算得出。式中，m为负极活性材料层的质量，单位：g；Ar为负极活性材料层的面积，单位：mm2。
负极活性材料层的压实密度的测试：
负极活性材料层的压实密度Pa通过公式：Pa＝Ma/Va计算得出。式中，Ma为负极活性材料层的质量，单位：g；Va为负极活性材料层的体积，单位：cm3，其中，体积Va是负极活性材料层的面积Sa与负极活性材料层的厚度之积。
晶格指数OI的测试：
使用X射线(XRD)衍射仪测试负极活性材料的晶格指数OI值：将负极活性材料层置于XRD衍射仪中，测得(004)和(110)峰的晶面面积分别为C(004)和C(110)，并按照下式计算OI值：OI值＝C(004)/C(110)。
高温存储性能的测试：
每个实施例或对比例测试10个锂离子电池，取平均值为最终结果。在25℃下，将锂离子电池静置30分钟，然后以0.7C恒流充电至3.65V，再在3.65V下恒压充电至0.05C，静置5分钟，测量锂离子电池的厚度，记为存储前厚度；然后在湿度85％、温度80℃、电压3.65V下储存1008小时后，测量锂离子电池的厚度，记为存储后厚度，再通过下式计算 锂离子电池的厚度膨胀率：厚度膨胀率＝[(存储后厚度/存储前厚度)－1]×100％。
通过个数是指每个实施例或对比例测试的10个锂离子电池中，厚度膨胀率小于或等于12％的锂离子电池数量。
实施例1-1
<电解液的制备>
在干燥的氩气气氛手套箱中，将EC、PC、DEC混合得到有机溶剂，然后向有机溶剂中加入锂盐LiPF6溶解并混合均匀，再加入氟代碳酸乙烯酯和己二腈得到电解液。其中，LiPF6在电解液中的浓度为1.0mol/L；基于电解液的质量，EC的质量百分含量为8％、氟代碳酸乙烯酯的质量百分含量为3％、己二腈的质量百分含量为3％；其余为PC和DEC，PC和DEC的质量比为1:2。
<负极极片的制备>
将负极活性材料石墨、丁苯橡胶(SBR)、羧甲基纤维素钠(CMC)按照质量比为95:2:3进行混合，加入去离子水，在真空搅拌机作用下搅拌均匀，获得负极浆料，其中负极浆料的固含量为75wt％。将负极浆料均匀涂覆于厚度为12μm的负极集流体铜箔的一个表面上，将铜箔在120℃下烘干，得到涂层厚度为1.5μm的单面涂覆有负极活性材料层的负极极片。在铜箔的另一个表面上重复以上步骤，即得到双面涂布负极活性材料层的负极极片。然后经过干燥、冷压、裁片、分切后得到规格为87.6mm×700.8mm(长度L为700.8mm，宽度W为87.6mm)的负极极片。其中，负极活性材料的晶格指数OI为18、R值为0.15，负极活性材料层的面密度为0.08mg/mm2、压实密度为1.7g/cm3，负极极片的电导率σ为15S/cm。
<正极活性材料的制备>
(1)前驱体：将硫酸镍、硫酸钴、硫酸锰按照n(Ni):n(Co):n(Mn)＝0.5:0.2:0.3配制成摩尔溶度2mol/L的混合盐溶液，氢氧化钠配制成摩尔浓度4mol/L的碱溶液，用浓度4mol/L的氨水作为络合剂；所有配制好的溶液要先经过过滤，去除固体杂质后才能进入下一个环节；将过滤后的混合盐溶液、碱溶液、络合剂以流量30L/h加入到反应釜，控制反应釜的搅拌速率为30r·min-1、反应浆料的温度为常温、pH为11.5，使盐、碱发生中和反应生成三元前驱体晶核并逐渐长大，当平均粒径达到3.5μm后，将反应浆料过滤、洗涤、干燥得到三元前驱体；
(2)一次混料：将锂源Li2CO3与前驱体按照n(Li):n(Ni):n(Co):n(Mn)＝1.05:0.5:0.2:0.3配料后置于高混机中加入到匣钵中进行下一步一次烧结工序；
(3)一次烧结：将步骤(2)中混合均匀的装入匣钵中的物料置于窑炉中先在空气气氛中以升温速率5℃/min缓慢升温至一次烧结温度700℃进行预烧，再在该一次烧结温度下的空气气氛煅烧12h得到一次烧结物料；
(4)机械破碎及气流粉碎：将步骤(3)中得到的一次烧结物料冷却后进行机械破碎、气流粉碎以及分级处理；
(5)二次烧结包覆：将步骤(4)中粉碎及分级处理后的一次烧结物料与包覆添加剂氧化铝按100:0.5的质量比混合后在高混机中混合均匀，装入匣钵后置于窑炉中，在空气气氛中煅烧6h后，将获得物料经过机械制粉分级、除磁、筛粉获得正极活性材料。
<正极极片的制备>
将上述制备得到的正极活性材料锂镍钴锰氧、乙炔黑、聚偏二氟乙烯按照质量比为96:2:2进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌均匀，获得正极浆料，其中正极浆料的固含量为70wt％。将正极浆料均匀涂覆于厚度为12μm的正极集流体铝箔的一个表面上，将铝箔在120℃下烘干，得到单面涂覆有正极活性材料层的正极极片。在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极活性材料层的正极极片。然后经过干燥、冷压、裁片、分切后得到规格为86mm×698.8mm的正极极片。
<隔膜的制备>
采用厚度为7μm的多孔聚乙烯薄膜(Celgard公司提供)。
<锂离子电池的制备>
将上述制备得到的正极极片、隔膜、负极极片按顺序叠好，使隔膜处于正极极片和负极极片中间起到隔离的作用，卷绕得到电极组件。将电极组件置于铝塑膜包装袋中，干燥后注入电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。
实施例1-2至实施例1-9
除了按照表1调整相关制备参数以外，其余与实施例1-1相同。
实施例2-1至实施例2-8
除了按照表2调整相关制备参数以外，其余与实施例1-1相同。
实施例3-1至实施例3-7
除了按照表3调整相关制备参数以外，其余与实施例1-1相同。
对比例1至对比例6
除了按照表1调整相关制备参数以外，其余与实施例1-1相同。
各实施例和对比例的制备参数和性能参数如表1至表3所示。
表1
从实施例1-1至实施例1-9和对比例1至对比例6可以看出，锂离子电池的高温存储性能随着负极集流体的长度L与负极集流体的宽度W的比值L/W和负极活性材料的R值的变化而变化。L/W的值和R值均在本申请范围内的锂离子电池，具有较大的DCR(如相对于对比例1)，且具有更小的厚度膨胀率和更高的通过个数，表明锂离子电池具有更好的高温存储性能。
从实施例1-1至实施例1-9和对比例3至对比例6可以看出，L/W的值和R值均在本申请范围内的锂离子电池(如实施例1-1至实施例1-9)，相比于L/W的值或R值不在本申请范围内的锂离子电池(如对比例3至对比例6)，具有更小的厚度膨胀率和更高的通过个数，表明锂离子电池具有更好的高温存储性能。
图2示出了实施例1-4的负极活性材料的拉曼光谱图，如图2所示，图中具有位移范围在1300cm-1至1400cm-1的D峰和位移范围在1530cm-1至1630cm-1的G峰，其R值为0.30。
表2

EC在电解液中的质量百分含量通常会影响锂离子电池的高温存储性能。从实施例1-1、实施例2-1至实施例2-5中可以看出，EC在电解液中的质量百分含量在本申请范围内的锂离子电池，具有较大的DCR且具有较低的厚度膨胀率和较高的通过个数，即具有良好的高温存储性能。
锂盐的种类通常会影响锂离子电池的高温存储性能。从实施例2-4、实施例2-6和实施例2-7中可以看出，锂盐的种类在本申请范围内的锂离子电池，具有较大的DCR，且具有较低的厚度膨胀率和较高的通过个数，即具有良好的高温存储性能。
锂盐在电解液中的浓度通常会影响锂离子电池的高温存储性能。从实施例2-4、实施例2-8中可以看出，锂盐在电解液中的浓度在本申请范围内的锂离子电池，具有较大的DCR，且具有较低的厚度膨胀率和较高的通过个数，即具有良好的高温存储性能。
表3
负极极片的电导率σ通常会影响锂离子电池的高温存储性能。从实施例1-1、实施例3-1至实施例3-3中可以看出，负极极片的电导率σ在本申请范围内的锂离子电池，具有较大的DCR，且具有较低的厚度膨胀率和较高的通过个数，即具有良好的高温存储性能。
负极活性材料层的面密度通常会影响锂离子电池的高温存储性能。从实施例1-1、实施例3-4和实施例3-5中可以看出，负极活性材料层的面密度在本申请范围内的锂离子电 池，具有较大的DCR，且具有较低的厚度膨胀率和较高的通过个数，即具有良好的高温存储性能。
负极活性材料层的压实密度通常会影响锂离子电池的高温存储性能。从实施例1-1、实施例3-6和实施例3-7中可以看出，负极活性材料层的压实密度在本申请范围内的锂离子电池，具有较大的DCR，且具有较低的厚度膨胀率和较高的通过个数，即具有良好的高温存储性能。
以上所述仅为本申请的较佳实施例，并非用于限定本申请的保护范围。凡在本申请的精神和原则之内所作的任何修改、等同替换、改进等，均包含在本申请的保护范围内。

Claims (11)

  1. 一种电化学装置，其包括负极极片，所述负极极片包括负极集流体以及设置于所述负极集流体至少一个表面上的负极活性材料层，所述负极活性材料层包括负极活性材料；
    所述负极集流体的长度L与所述负极集流体的宽度W满足：8≤L/W≤40，40mm≤W≤145mm；
    所述负极活性材料的R值为0.1至0.4；
    所述R值为所述负极活性材料层上尺寸为100μm×100μm的任一区域内，所述负极活性材料颗粒采用拉曼测试的D峰与G峰的峰强比值I(D)/I(G)的平均值；
    所述D峰为所述负极活性材料颗粒的拉曼光谱中位移范围为1300cm-1至1400cm-1的峰，所述G峰为负极活性材料颗粒的拉曼光谱中位移范围为1530cm-1至1630cm-1的峰。
  2. 根据权利要求1所述的电化学装置，其中，所述电化学装置的阻抗为30mΩ至60mΩ。
  3. 根据权利要求1所述的电化学装置，其中，所述负极极片的电导率σ满足：15S/cm≤σ≤35S/cm。
  4. 根据权利要求1所述的电化学装置，其中，所述负极活性材料层的面密度为0.05mg/mm2至0.11mg/mm2。
  5. 根据权利要求1所述的电化学装置，其中，所述负极活性材料层的压实密度为1.6g/cm3至1.8g/cm3。
  6. 根据权利要求1所述的电化学装置，其中，所述电化学装置的荷电状态为0％时，所述负极活性材料的晶格指数OI满足：8≤OI≤20。
  7. 根据权利要求3所述的电化学装置，其满足以下特征(1)至(3)中的至少一者：
    (1)所述负极集流体的长度L与所述负极集流体的宽度W满足：18≤L/W≤40；
    (2)所述R值为0.15至0.30；
    (3)所述负极极片的电导率σ满足：25S/cm≤σ≤30S/cm。
  8. 根据权利要求1所述的电化学装置，其中，所述电化学装置包括电解液，所述电解液包括碳酸亚乙酯；
    基于所述电解液的质量，所述碳酸亚乙酯的质量百分含量为8％至30％。
  9. 根据权利要求8所述的电化学装置，其中，基于所述电解液的质量，所述碳酸亚乙酯的质量百分含量为15％至25％。
  10. 根据权利要求8所述的电化学装置，其中，所述电解液包括锂盐，所述锂盐包括 LiPF6、双氟磺酰亚胺锂或双三氟甲烷磺酰亚胺锂中的至少一种；
    所述锂盐在所述电解液中的浓度为0.9mol/L至1.5mol/L。
  11. 一种电子装置，其包括权利要求1至10中任一项所述的电化学装置。
PCT/CN2023/109567 2022-08-01 2023-07-27 电化学装置及包含该电化学装置的电子装置 WO2024027551A1 (zh)

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JP2016009566A (ja) * 2014-06-24 2016-01-18 株式会社豊田中央研究所 リチウムイオン二次電池
JP2019179687A (ja) * 2018-03-30 2019-10-17 三菱ケミカル株式会社 人造黒鉛系負極材、非水系二次電池用負極及び非水系二次電池
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