CN116230933A - Method for removing alkali from surface of pre-lithiated anode material - Google Patents
Method for removing alkali from surface of pre-lithiated anode material Download PDFInfo
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- CN116230933A CN116230933A CN202211623593.8A CN202211623593A CN116230933A CN 116230933 A CN116230933 A CN 116230933A CN 202211623593 A CN202211623593 A CN 202211623593A CN 116230933 A CN116230933 A CN 116230933A
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- 239000010405 anode material Substances 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 51
- 239000003513 alkali Substances 0.000 title claims abstract description 37
- 238000006138 lithiation reaction Methods 0.000 claims abstract description 27
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 24
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 20
- 239000011248 coating agent Substances 0.000 claims abstract description 17
- 238000000576 coating method Methods 0.000 claims abstract description 17
- 238000002791 soaking Methods 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 16
- 239000012298 atmosphere Substances 0.000 claims abstract description 13
- 238000001291 vacuum drying Methods 0.000 claims abstract description 12
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims abstract description 10
- 239000000126 substance Substances 0.000 claims abstract description 8
- 239000010406 cathode material Substances 0.000 claims abstract description 7
- 238000005229 chemical vapour deposition Methods 0.000 claims abstract description 6
- 239000002243 precursor Substances 0.000 claims abstract description 6
- 239000002904 solvent Substances 0.000 claims abstract description 5
- 230000001681 protective effect Effects 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims description 21
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 8
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 8
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 8
- 229910000103 lithium hydride Inorganic materials 0.000 claims description 8
- 229910002804 graphite Inorganic materials 0.000 claims description 7
- 239000010439 graphite Substances 0.000 claims description 7
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 claims description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- -1 lithium aluminum hydride Chemical compound 0.000 claims description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 4
- 239000005049 silicon tetrachloride Substances 0.000 claims description 4
- 229910021627 Tin(IV) chloride Inorganic materials 0.000 claims description 3
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical compound Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 claims description 3
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 2
- 239000005977 Ethylene Substances 0.000 claims description 2
- 239000012448 Lithium borohydride Substances 0.000 claims description 2
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000011247 coating layer Substances 0.000 claims description 2
- AFRJJFRNGGLMDW-UHFFFAOYSA-N lithium amide Chemical compound [Li+].[NH2-] AFRJJFRNGGLMDW-UHFFFAOYSA-N 0.000 claims description 2
- IDBFBDSKYCUNPW-UHFFFAOYSA-N lithium nitride Chemical compound [Li]N([Li])[Li] IDBFBDSKYCUNPW-UHFFFAOYSA-N 0.000 claims description 2
- 238000007669 thermal treatment Methods 0.000 claims 2
- 239000012280 lithium aluminium hydride Substances 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 14
- 230000000694 effects Effects 0.000 abstract description 9
- 238000011065 in-situ storage Methods 0.000 abstract description 5
- 238000004321 preservation Methods 0.000 description 16
- 238000001816 cooling Methods 0.000 description 11
- 239000010410 layer Substances 0.000 description 10
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 8
- 239000007773 negative electrode material Substances 0.000 description 8
- 239000010703 silicon Substances 0.000 description 8
- 229910052710 silicon Inorganic materials 0.000 description 8
- 239000012300 argon atmosphere Substances 0.000 description 7
- 239000011259 mixed solution Substances 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 6
- SIAPCJWMELPYOE-UHFFFAOYSA-N lithium hydride Chemical compound [LiH] SIAPCJWMELPYOE-UHFFFAOYSA-N 0.000 description 5
- 239000002210 silicon-based material Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 229910052718 tin Inorganic materials 0.000 description 3
- 239000013543 active substance Substances 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000013557 residual solvent Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 229910003902 SiCl 4 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 1
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 150000002642 lithium compounds Chemical class 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 235000019837 monoammonium phosphate Nutrition 0.000 description 1
- 239000006012 monoammonium phosphate Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000002153 silicon-carbon composite material Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000011135 tin Substances 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
Classifications
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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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
- 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
-
- 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
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- Chemical Kinetics & Catalysis (AREA)
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- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Carbon And Carbon Compounds (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a method for removing alkali on the surface of a pre-lithiated anode material, which comprises the following steps: s1, carrying out pre-lithiation treatment on a lithium ion battery cathode material; s2, preserving heat of the anode material subjected to the pre-lithiation treatment at 50-800 ℃ for 0.5-6 hours, and introducing reactive gas in an inert atmosphere to obtain an activated anode material; s3, soaking the activated anode material in a solvent and carrying out vacuum drying to obtain a precursor A; s4, coating the precursor A with chemical vapor deposition carbon in a protective atmosphere. The invention adopts simple chemical reaction, can convert the residual alkali on the surface of the anode material after the pre-lithium into the material with chemical activity in situ, namely, reduces the influence on the capacity of the anode material while solving the residual alkali on the surface, and even further improves the capacity of the anode material. Meanwhile, the method can be introduced in the pre-lithiation process, and can also be used for treating the anode material after the pre-lithiation is finished, so that the process is simple and efficient.
Description
Technical Field
The invention belongs to the technical field of lithium ion battery materials, and particularly relates to a method for removing alkali from the surface of a pre-lithiated anode material.
Background
Lithium ion battery technology has penetrated aspects of life since the first application of sony in 1991, such as portable electronic devices, energy storage facilities, and more mature electric automobiles in recent years. Due to these demands on the application end, the energy density of lithium ion batteries is also gradually increasing. The actual capacity of the traditional graphite cathode material is close to the theoretical specific capacity, and the improvement of the battery energy density is almost impossible by improving the specific capacity of the graphite cathode material.
In order to realize the jump of the energy density of the battery, the development of a new generation of high specific capacity anode materials, such as silicon, tin and other alloy type anode materials, is a common knowledge in academia and industry. However, such alloy materials have a common disadvantage in that they undergo substantial volumetric expansion during circulation, resulting in particle breakage, pulverization and eventual failure; in addition, the huge volume expansion causes more silicon-based materials to be exposed to the electrolyte, forming more SEI films, and thus the first coulombic efficiency of the silicon-based materials is lower. In particular, for silicon oxygen materials, an inert lithium compound is irreversibly formed during the first lithium intercalation process, and thus has a lower first coulombic efficiency than elemental Si. The lower first coulombic efficiency of the silicon-based negative electrode material greatly consumes lithium source from the limited positive side, resulting in lower energy density of the battery.
The pre-lithiation technique is thus developed for the lower first coulombic efficiency of silicon-based anode materials. The lithium source consumed in the first cycle process of the battery is compensated by additionally supplementing lithium to the silicon-based material before the silicon-based material is assembled into the battery, so that the first coulomb efficiency and the energy density are improved. The prior pre-lithiation technology mainly comprises electrochemical pre-lithiation, wet chemical pre-lithiation, SLMP, thermal doping pre-lithiation and the like. However, the silicon-based material inevitably generates the problem of residual alkali on the surface even dead lithium after prelithiation, which affects the subsequent processing performance of the negative electrode material and ultimately affects the battery performance. At present, the processing performance of the material is improved mainly by a method of preventing residual alkali from being dissolved in the pulping process and eliminating surface residual alkali through wet chemical reaction through coating of a barrier layer, but the method inevitably causes the capacity reduction of the cathode material.
Patent CN111710845a discloses a silicon-oxygen composite negative electrode material, a preparation method thereof and a lithium ion battery, wherein the silicon-oxygen composite negative electrode material is obtained by roasting a mixture containing a silicon source and a lithium-containing compound in a protective gas atmosphere, and the silicon-oxygen negative electrode material is pre-lithiated. After the prelithiation is finished, the silicon-oxygen composite anode material is immersed in a hydrophobic solution and subjected to solid-liquid separation, so that the subsequent slurry mixing performance of the battery is improved, and the problem of residual alkali on the surface is solved. However, the hydrophobic layer introduced into the surface of the method has no chemical activity, the capacity of the anode material is necessarily reduced, and the method also does not thoroughly solve the problem of residual alkali on the surface and only has a certain relieving effect. If the size mixing time is prolonged, the severe problem of residual alkali is also faced.
Patent WO2021/254142A1 discloses a silicon-carbon composite material for a secondary lithium battery and a preparation method thereof, wherein conductive layer coating and ion conducting layer coating are carried out on the surface of a pre-lithiated silicon-oxygen material. The ion conducting layer is coated, so that the subsequent processing performance of the material is good, the slurry is stable, and the problem of residual alkali on the surface is relieved through surface coating. The method also faces that the coated ion conducting layer has no chemical activity and can certainly drag down the capacity of the anode material, and the method also does not thoroughly solve the problem of residual alkali on the surface and only has a certain relieving effect.
In view of this, the present invention has been made.
Disclosure of Invention
Aiming at the problems in the prior art, the invention can thoroughly solve the problem of residual alkali after the anode material is pre-lithiated, further improve the capacity of the anode material and has wide commercial application prospect.
In order to solve the technical problems, the invention provides the following technical scheme:
a method for surface dealkalization of a pre-lithiated anode material, the method comprising the steps of:
s1, carrying out pre-lithiation treatment on a lithium ion battery cathode material;
preferably, the lithium ion battery anode material is at least one selected from graphite anode material, silicon oxygen anode material and silicon carbon anode material. The above-described anode material is required to improve the initial efficiency or energy density by a prelithiation treatment.
Preferably, the pre-lithiation treatment is selected from at least one of electrochemical pre-lithium, wet chemical pre-lithium, thermally doped pre-lithium, preferably thermally doped pre-lithium. Because the thermally doped pre-lithium can be used for carrying out seamless cooperative connection on the subsequent surface alkali removal process after the heating is completed, if other pre-lithium modes are adopted, the heat treatment equipment is required to be transferred to start the surface alkali removal process.
Preferably, the thermally doped pre-lithium comprises the steps of: and uniformly mixing the lithium ion battery anode material and the pre-lithiation agent in argon or vacuum atmosphere, and then performing heat treatment, wherein the heat treatment temperature is 100-1000 ℃, preferably 500-900 ℃, and the heat treatment time is 1-10h, preferably 3-6h.
Preferably, the pre-lithiating agent is at least one selected from lithium hydride, metallic lithium, aluminum lithium hydride, alkyl lithium, lithium nitride, lithium amide, lithium borohydride. Taking lithium hydride as an example, the mass ratio of the anode material to the pre-lithiating agent is 50:1 to 1:1, preferably 30:1 to 5: 1.
S2, preserving heat of the anode material subjected to the pre-lithiation treatment at 50-800 ℃ for 0.5-6h, wherein the temperature is preferably 200-500 ℃ and the time is preferably 1-3h, introducing reactive gas in inert atmosphere, and obtaining the activated anode material after the reaction is finished;
preferably, the reactive gas is silicon tetrachloride or tin tetrachloride, and the action mechanism can be summarized as the following two chemical reaction formulas, but is not limited to reactants in the two reaction formulas:
SiCl 4 +4Li＝Si+4LiCl
2SiCl 4 +4Li 2 O＝2SiO 2 +8LiCl
through the reaction, residual alkali (lithium, lithium oxide and the like which are not completely reacted) on the surface of the anode material after the pre-lithium is reacted with silicon tetrachloride, tin tetrachloride and the like in situ, and the residual alkali is converted into silicon, tin, silicon oxide, tin oxide, lithium chloride and the like, wherein the silicon and the tin are active substances with extremely high capacity.
Preferably, the inflow amount of the reactive gas is 0.01-1L/min.
Preferably, if the pre-lithiation treatment is heat-doped pre-lithiation, the process is performed in a cooling stage of the heat treatment, that is, the negative electrode material is kept at 50-800 ℃ for 1-6 hours in the cooling stage of the heat treatment, and the reactive gas is introduced into the original inert atmosphere.
Preferably, if the pre-lithiation treatment is not a thermal doping method pre-lithiation, the temperature of the pre-lithiated anode material is directly raised to 50-800 ℃ in an inert atmosphere for 1-6 hours, and the corresponding reactive gas is introduced.
S3, soaking the activated anode material in a solvent and carrying out vacuum drying to obtain a precursor A;
preferably, the solvent is at least one of water and ethanol, the soaking time is 1-60min, and the soaking and vacuum drying are performed for 0-3 times. Among them, soaking can remove excessive byproducts such as LiCl. If the amount of LiCl is small, soaking, that is, soaking and vacuum drying may be performed 0 times, because a small amount of LiCl can be dissolved in the electrolyte, and at the same time, the generation of the SEI film is promoted, improving the cycle stability. The residual solvent after soaking can be removed by drying, so that the residual solvent is prevented from affecting the battery performance.
S4, coating the precursor A with Chemical Vapor Deposition (CVD) carbon in a protective atmosphere;
preferably, the chemical vapor deposition temperature is 500-1000 ℃, at least one of methane, ethane, ethylene and acetylene is introduced as a carbon source, the coating time is 0.5-12h, and the thickness of the carbon coating layer is 2-200 nm, preferably 5-50 nm.
The carbon coating functions as follows: silicon-based anode materials are currently accepted to require a carbon layer to be coated outside the materials to improve conductivity due to poor conductivity. Meanwhile, the carbon layer can cover a high-capacity micro-region, such as a Si micro-region, generated in the surface alkali removal process and buffer the volume expansion of the high-capacity micro-region.
The graphite anode material can generate SEI film in the first cycle circulation process, so that the first effect is lower. One of the methods known to date is to coat an amorphous carbon layer. Meanwhile, the carbon layer can also cover high-capacity micro-areas generated in the surface alkali removal process, such as Si micro-areas, and buffer the volume expansion of the high-capacity micro-areas.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts simple chemical reaction, can convert the residual alkali on the surface of the anode material after the pre-lithium into the material with chemical activity in situ, namely, reduces the influence on the capacity of the anode material while solving the residual alkali on the surface, and even further improves the capacity of the anode material. Meanwhile, the method can be introduced in the pre-lithiation process, and can also be used for treating the anode material after the pre-lithiation is finished, so that the process is simple and efficient. The concrete explanation is as follows:
1. the method has the advantages that the reactive gas is introduced into the existing pre-lithiation process or the pre-lithiated anode material under the heating condition, and the reaction is thorough due to the large gas-solid reaction contact area, so that the surface residual alkali of the anode material is reacted in situ to generate the chemical active substance with higher capacity, the influence on the capacity of the anode material is reduced while the residual alkali is removed, and even the capacity of the anode material can be improved;
2. the method can be even used for constructing the silicon-carbon structure cathode, namely, the silicon tetrachloride is introduced to react after the graphite is mixed with the lithium source, thereby avoiding the use of SiH 4 The risk of gas deposition of silicon;
3. the byproduct generated in situ by the method is mainly LiCl. Under a certain degree, the SEI film can be dissolved in electrolyte, and meanwhile, the generation of the SEI film is promoted, so that the cycling stability is improved;
4. the method has simple process, is compatible with the prior art, and has wide market prospect.
Detailed Description
The technical solutions and the technical problems to be solved in the embodiments of the present invention will be described below in conjunction with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present patent.
Example 1
SiO and LiH were mixed according to 12:1, and preserving the temperature for 6 hours at 800 ℃ under the argon atmosphere. Cooling to 300 ℃ after heat preservation is finished, and preserving heat for 1h, and introducing SiCl at a flow rate of 0.03L/min during the heat preservation 4 And (5) cooling to room temperature after the heat preservation is finished. The resulting material was prepared using water and ethanol 1:9 soaking the mixed solution for 5 minutes, and immediately after the completion, vacuum drying at 80 ℃. The dried product was kept at 800℃for 1 hour, and acetylene gas was introduced during this period so that the carbon coating amount was 2% (mass content).
Example 2
SiO and LiH were mixed according to 12:1, and preserving the temperature for 6 hours at 800 ℃ under the argon atmosphere. Cooling to 300 ℃ after heat preservation is finished, and preserving heat for 1h, and introducing SiCl at a flow rate of 0.03L/min during the heat preservation 4 And (3) heating the gas to 800 ℃ after the heat preservation at 300 ℃ is finished, and preserving the heat for 1h, and introducing acetylene gas during the heat preservation, so that the carbon coating amount is 2%.
Example 3
SiO and LiH were mixed according to 12:1, and preserving the temperature for 6 hours at 800 ℃ under the argon atmosphere. Cooling to 300 ℃ after the heat preservation is finished, preserving the heat for 1h, and introducing SiCl at a flow rate of 0.1L/min during the heat preservation 4 And (5) cooling to room temperature after the heat preservation is finished. The resulting material was prepared using water and ethanol 1:9 soaking the mixed solution for 5 minutes, and immediately after the completion, vacuum drying at 80 ℃. The dried product was kept at 800℃for 1 hour, and acetylene gas was introduced during this period so that the carbon coating amount was 2%.
Example 4
SiO and Li were mixed according to 14:1, and preserving the temperature for 6 hours at 800 ℃ under the argon atmosphere. Cooling to 300 ℃ after heat preservation is finished, and preserving heat for 1h, and introducing SiCl at a flow rate of 0.03L/min during the heat preservation 4 And (5) cooling to room temperature after the heat preservation is finished. The resulting material was prepared using water and ethanol 1:9 soaking the mixed solution for 5 minutes, and immediately after the completion, vacuum drying at 80 ℃. The dried product is kept at 800 ℃ for 1h, and is introduced in the periodAcetylene gas so that the carbon coating amount was 2%.
Example 5
Graphite material and Li were mixed according to 20:1, and preserving the temperature for 6 hours at 600 ℃ under the argon atmosphere. Cooling to 400 ℃ after the heat preservation is finished, preserving the heat for 3 hours, and introducing SiCl at a flow rate of 0.1L/min during the heat preservation 4 And (5) cooling to room temperature after the heat preservation is finished. The resulting material was prepared using water and ethanol 1:9 soaking the mixed solution for 5 minutes, and immediately after the completion, vacuum drying at 80 ℃. The dried product was kept at 800℃for 1 hour, and acetylene gas was introduced during this period so that the carbon coating amount was 2%.
Comparative example 1
SiO and LiH were mixed according to 12:1, and preserving the temperature for 6 hours at 800 ℃ under the argon atmosphere. The resulting material was soaked with ammonium fluoride solution at 60 ℃ for 1h, followed by water and ethanol 1:9 soaking the mixed solution for 5 minutes, and immediately after the completion, vacuum drying at 80 ℃. The dried product was kept at 800℃for 1h, and acetylene gas was introduced during this period to give a carbon coating of 2%.
Comparative example 2
SiO and LiH were mixed according to 12:1, and preserving the temperature for 6 hours at 800 ℃ under the argon atmosphere. The resulting material was soaked with monoammonium phosphate solution at 60 ℃ for 1h, followed by water and ethanol 1:9 soaking the mixed solution for 5 minutes, and immediately after the completion, vacuum drying at 80 ℃. The dried product was kept at 800℃for 1h, and acetylene gas was introduced during this period to give a carbon coating of 2%.
The negative electrode materials obtained in the above examples and comparative examples were assembled and buckled for performance testing. Mixing a cathode material, acetylene black and a binder according to a mass ratio of 85:5:10, wherein the binder is a mixed binder with a mass ratio of CMC to SBR of 3:8, and 1mol/L LiPF is used 6 in EC: dmc=1:1:1vol% was electrolyte, lithium metal sheets were counter electrodes, and CR2032 cells were assembled in a glove box. After 10h of standing, the test was performed on a blue electric test system at a charge-discharge rate of 0.1C, and the delithiation cut-off voltage was 1.0V. The pH value test method is to dissolve 2g of the anode material in 250g of water, stir for 2h and measure by a pH meter.
The buckling test results are shown in table 1:
TABLE 1
As can be seen from Table 1, the method provided by the invention can effectively remove residual alkali on the surface of the anode material, and can reduce the influence on the capacity of the anode material while solving the residual alkali on the surface, and even further improve the capacity of the anode material. The comparative examples 1 and 2 both adopt the representative residual alkali removal mode at present, and the first effect and the capacity of the two methods are obviously lower than those of examples 1 to 4, and the pH value is obviously higher than that of the negative electrode material provided by the invention. After the existing graphite negative electrode is pre-lithiated by adopting the method provided in the example 5, the first effect is obviously improved, the capacity is further improved, and the theoretical specific capacity is exceeded.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A method for surface dealkalization of a pre-lithiated anode material, comprising the steps of:
s1, carrying out pre-lithiation treatment on a lithium ion battery cathode material;
s2, preserving heat of the anode material subjected to the pre-lithiation treatment at 50-800 ℃ for 0.5-6 hours, and introducing reactive gas in inert atmosphere to obtain an activated anode material after the reaction is finished;
s3, soaking the activated anode material in a solvent and carrying out vacuum drying to obtain a precursor A;
s4, coating the precursor A with chemical vapor deposition carbon in a protective atmosphere.
2. The method for removing alkali from the surface of a pre-lithiated anode material of claim 1, wherein in step S1, the lithium ion battery anode material is selected from at least one of a graphite anode material, a silicon oxygen anode material, and a silicon carbon anode material.
3. The method for surface alkali removal for a prelithiated anode material according to claim 1, characterized in that in step S1, the prelithiation treatment is selected from at least one of electrochemical prelithiation, wet chemical prelithiation, thermally doped prelithiation, preferably thermally doped prelithiation.
4. The method for surface alkali removal for a prelithiated anode material of claim 3, wherein the thermally doped prelithiation comprises the steps of: and uniformly mixing the lithium ion battery anode material and the pre-lithiation agent in argon or vacuum atmosphere, and then performing heat treatment, wherein the heat treatment temperature is 100-1000 ℃, preferably 500-900 ℃, and the heat treatment time is 1-10h, preferably 3-6h.
5. The method for surface alkali removal for a prelithiated anode material of claim 4, wherein the prelithiation agent is at least one selected from lithium hydride, lithium metal, lithium aluminum hydride, alkyl lithium, lithium nitride, lithium amide, lithium borohydride.
6. The method for removing alkali from the surface of a pre-lithiated anode material according to claim 3, wherein in step S2, the reactive gas is silicon tetrachloride or tin tetrachloride, and preferably the amount of the reactive gas introduced is 0.01 to 1L/min.
7. The method for removing alkali from the surface of a pre-lithiated anode material according to claim 6, wherein if the pre-lithiation treatment is a thermally doped pre-lithiation, the process is performed in a temperature reduction stage of the thermal treatment, i.e., the anode material is kept at 50-800 ℃ for 1-6 hours in the temperature reduction stage of the thermal treatment, and a reactive gas is introduced into the original inert atmosphere.
8. The method for removing alkali from the surface of a pre-lithiated anode material according to claim 6, wherein if the pre-lithiation treatment is not a thermal doping method pre-lithiation, the pre-lithiated anode material is directly heated to 50-800 ℃ in an inert atmosphere for 1-6 hours and a corresponding reactive gas is introduced.
9. The method for removing alkali from the surface of a pre-lithiated anode material according to claim 1, wherein in step S3, the solvent is at least one of water and ethanol, the soaking time is 1 to 60 minutes, and the soaking and vacuum drying are performed 0 to 3 times.
10. The method for removing alkali from the surface of the pre-lithiated anode material according to claim 1, wherein in step S4, the chemical vapor deposition temperature is 500-1000 ℃, at least one of methane, ethane, ethylene, and acetylene is introduced as a carbon source, the coating time is 0.5-12 hours, and the thickness of the carbon coating layer is 2-200 nm, preferably 5-50 nm.
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| CN116495744B (en) * | 2023-06-26 | 2023-10-03 | 北京壹金新能源科技有限公司 | Lithium doped silicon-based anode material and preparation method and application thereof |
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