CN114784235B - High-voltage composite positive plate, preparation method thereof and all-solid-state lithium battery - Google Patents
High-voltage composite positive plate, preparation method thereof and all-solid-state lithium battery Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims abstract description 72
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 59
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 55
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 239000007774 positive electrode material Substances 0.000 claims abstract description 76
- 229920000642 polymer Polymers 0.000 claims abstract description 61
- 239000007784 solid electrolyte Substances 0.000 claims abstract description 60
- 238000000034 method Methods 0.000 claims abstract description 59
- 239000002086 nanomaterial Substances 0.000 claims abstract description 34
- 230000008569 process Effects 0.000 claims abstract description 22
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 39
- 238000005245 sintering Methods 0.000 claims description 38
- 208000028659 discharge Diseases 0.000 claims description 24
- 238000000498 ball milling Methods 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 18
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 13
- 239000011248 coating agent Substances 0.000 claims description 13
- 238000000576 coating method Methods 0.000 claims description 13
- 238000000227 grinding Methods 0.000 claims description 13
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 12
- 238000003851 corona treatment Methods 0.000 claims description 12
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 claims description 12
- 229910001486 lithium perchlorate Inorganic materials 0.000 claims description 11
- 239000011259 mixed solution Substances 0.000 claims description 11
- 229910004283 SiO 4 Inorganic materials 0.000 claims description 9
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 claims description 9
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 238000003825 pressing Methods 0.000 claims description 9
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 8
- 239000011521 glass Substances 0.000 claims description 6
- 239000004677 Nylon Substances 0.000 claims description 4
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 claims description 4
- 229920001778 nylon Polymers 0.000 claims description 4
- 239000010935 stainless steel Substances 0.000 claims description 4
- 229910001220 stainless steel Inorganic materials 0.000 claims description 4
- PFYQFCKUASLJLL-UHFFFAOYSA-N [Co].[Ni].[Li] Chemical compound [Co].[Ni].[Li] PFYQFCKUASLJLL-UHFFFAOYSA-N 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 14
- 238000000354 decomposition reaction Methods 0.000 abstract description 7
- 230000003197 catalytic effect Effects 0.000 abstract description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 25
- 239000007789 gas Substances 0.000 description 25
- 229910001416 lithium ion Inorganic materials 0.000 description 25
- 230000000052 comparative effect Effects 0.000 description 15
- 239000012535 impurity Substances 0.000 description 15
- 230000005540 biological transmission Effects 0.000 description 14
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 13
- 229910052808 lithium carbonate Inorganic materials 0.000 description 13
- 239000007787 solid Substances 0.000 description 13
- 238000006555 catalytic reaction Methods 0.000 description 11
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 10
- 150000002500 ions Chemical class 0.000 description 8
- 239000002103 nanocoating Substances 0.000 description 8
- 239000011812 mixed powder Substances 0.000 description 7
- 239000000919 ceramic Substances 0.000 description 6
- 239000002105 nanoparticle Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 229910001182 Mo alloy Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910013684 LiClO 4 Inorganic materials 0.000 description 4
- RJEIKIOYHOOKDL-UHFFFAOYSA-N [Li].[La] Chemical compound [Li].[La] RJEIKIOYHOOKDL-UHFFFAOYSA-N 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
- -1 tungsten ions Chemical class 0.000 description 4
- 229910000846 In alloy Inorganic materials 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- 239000011324 bead Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- LHJOPRPDWDXEIY-UHFFFAOYSA-N indium lithium Chemical compound [Li].[In] LHJOPRPDWDXEIY-UHFFFAOYSA-N 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 150000002641 lithium Chemical group 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 230000008439 repair process Effects 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- 229910002991 LiNi0.5Co0.2Mn0.3O2 Inorganic materials 0.000 description 2
- 229910015872 LiNi0.8Co0.1Mn0.1O2 Inorganic materials 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910013716 LiNi Inorganic materials 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002290 gas chromatography-mass spectrometry Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 1
- 239000005518 polymer electrolyte Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000012360 testing method Methods 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
-
- 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
-
- 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
- H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
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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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
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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
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
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Abstract
The invention discloses a high-voltage composite positive plate, a preparation method thereof and an all-solid-state lithium battery, and relates to the technical field of lithium batteries, wherein the preparation method of the high-voltage composite positive plate comprises the following steps: s1, preparing a W-LLZO nano material; s2, preparing a W-LLZO coated high-voltage positive electrode material; s3, preparing a high-voltage composite positive plate; and S4, treating the high-voltage composite positive plate obtained in the step S3 by adopting a repeated pulse corona discharge method. The high-voltage composite positive plate prepared by the method can effectively inhibit the catalytic effect of the high-voltage positive electrode material on the decomposition of the polymer solid electrolyte, improve the interface performance of the high-voltage positive electrode and the polymer solid electrolyte, reduce the gas production rate of the lithium battery in the charge-discharge cycle process, and greatly improve the safety of the battery.
Description
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a high-voltage composite positive plate, a preparation method thereof and an all-solid-state lithium battery.
Background
Polyethylene oxide (PEO) -based solid polymer batteries are expected to play a role in the next generation of high energy density lithium ion battery technologyThe bond action, however, with the introduction of high voltage positive electrodes, safety issues associated with PEO decomposition and concomitant gas release have attracted considerable attention. At present, in a solid battery taking lithium metal as a negative electrode, the surface catalysis of a high-voltage positive electrode material is found to be due to the fact that PEO-based polymer solid electrolyte releases hydrogen H within the range of 3.0-4.2V 2 And the constant generation and accumulation of gases can cause cell swelling, deformation, thermal runaway and other safety hazards. Therefore, an effective strategy is needed to enhance the interfacial stability of the high-voltage positive electrode/polymer solid electrolyte, and avoid the generation of gas, thereby improving the safety of the solid battery.
Disclosure of Invention
1. Technical problem to be solved by the invention
Aiming at the technical problems that the existing lithium battery is high in gas production efficiency and safety due to the fact that high-voltage positive electrode materials are easy to catalyze polymer solid electrolyte, the invention provides a high-voltage composite positive electrode plate and a preparation method thereof, and an all-solid-state lithium battery.
2. Technical proposal
In order to solve the problems, the technical scheme provided by the invention is as follows:
the preparation method of the high-voltage composite positive plate comprises the following steps:
s1, preparing a W-LLZO nano material: liOH, la (OH) 3 、ZrO 2 And WO 3 Mixing absolute ethyl alcohol, performing vibration ball milling, and then sintering to obtain a W-LLZO nano material with a cubic structure;
s2, preparing a W-LLZO coated high-voltage positive electrode material: mixing the W-LLZO nano material, the high-voltage positive electrode material and the sintering aid obtained in the step S1, performing vibration ball milling, and then sintering to obtain the W-LLZO coated high-voltage positive electrode material;
s3, preparing a high-voltage composite positive plate: carrying out mould pressing and pressing on the W-LLZO coated high-voltage positive electrode material obtained in the step S2 to obtain a high-voltage composite positive electrode plate;
and S4, treating the high-voltage composite positive plate obtained in the step S3 by adopting a repeated pulse corona discharge method.
The W-LLZO nano material prepared by the method has the advantages that due to the doping of tungsten ions, compared with a pure lanthanum lithium zirconate LLZO nano material, the cubic structure stability of LLZO is improved, and the ceramic density and the lithium ion conductivity are higher. Meanwhile, the W-LLZO coated high-voltage positive electrode material prepared by the method has the advantages that the W-LLZO nano coating with high density is coated on the surface of the high-voltage positive electrode material, so that on one hand, the direct contact between the high-voltage positive electrode material and the polymer solid electrolyte is isolated, the catalysis is inhibited, and meanwhile, the transmission channel of lithium ions in positive electrode particles can be effectively ensured due to the fact that the W-LLZO has lithium ion conductivity. In addition, in consideration of the fact that the W-LLZO nano particles and the high-voltage positive electrode material are extremely easy to generate lithium carbonate impurities with low ion conductivity and low oxidation potential on the surfaces of the W-LLZO nano particles and the high-voltage positive electrode material during sintering, the method adopts a repeated pulse corona discharge method to treat the obtained high-voltage composite positive electrode plate, so that lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode material can be rapidly and effectively removed, lithium ion transmission characteristics are improved, interfacial gas precipitation is further restrained, and the method is high in efficiency, environment-friendly and free of third-party impurities. In a word, the high-voltage composite positive plate prepared by the method can effectively inhibit the catalytic effect of the high-voltage positive electrode material on the decomposition of the polymer solid electrolyte, improve the interface performance of the high-voltage positive electrode and the polymer solid electrolyte, reduce the gas production rate of the lithium battery in the charge-discharge cycle process, and greatly improve the safety of the battery.
Optionally, in step S1, the ball milling time is 3-6h, the sintering temperature is 800-1000 ℃ and the sintering time is 10-15h. Compared with the pure lanthanum lithium zirconate LLZO nanomaterial, the W-LLZO nanomaterial prepared by the method not only improves the cubic structure stability of LLZO, but also has higher ceramic density and high lithium ion conductivity.
Optionally, in step S1, liOH, la (OH) 3 、ZrO 2 And WO 3 The mass ratio of (2) is 6-8:2-4:1-3:0.05 to 0.09 percent of absolute ethyl alcohol accounting for 4 to 9 percent of the total mass of the material. For LiOH, la (OH) 3 、ZrO 2 And WO 3 The mass ratio and the dosage of the absolute ethyl alcohol are limited, the W-LLZO nano material with strong cubic structure stability, high ceramic density and high ion conductivity can be synthesized, and lithium loss in the synthesis process can be effectively compensated.
Optionally, in step S1, the ball-to-material ratio in the vibration ball milling process is 20-40:60-80, wherein the grinding ball is selected from any one of zirconia balls, alumina balls, stainless steel balls, zirconium silicate balls and nylon balls. The definition of the parameter can improve the grinding efficiency and the grinding quality.
Optionally, in step S2, the ball milling time is 30-45min, and the mass ratio of the W-LLZO nanomaterial, the high-voltage cathode material and the sintering aid is 3-8:55-70:1.5-3, the sintering aid is Li 4 SiO 4 Or Li (lithium) 2 ZrO 3 The method comprises the steps of carrying out a first treatment on the surface of the The sintering temperature is 550-800 ℃ and the sintering time is 4-8h. Through limiting each parameter and limiting the dosage of each component, the surface of the high-voltage positive electrode material can be uniformly coated with a W-LLZO nano coating, so that the direct contact between the high-voltage positive electrode material and the polymer solid electrolyte is effectively isolated, and the catalysis is inhibited. At the same time, adopt Li 4 SiO 4 Or Li (lithium) 2 ZrO is used as a sintering aid, so that on one hand, the sintering temperature is reduced, lithium loss in the sintering process is reduced, and meanwhile, the ionic conductivity of LLZO can be improved. Therefore, the W-LLZO coated high-voltage positive electrode material prepared by the method can effectively isolate the direct contact between the high-voltage positive electrode material and the polymer solid electrolyte, inhibit the catalysis, and effectively ensure the transmission channel of lithium ions in the positive electrode particles.
Optionally, in step S2, the high-voltage cathode material is one or more of lithium cobaltate, lithium nickel cobalt manganate and lithium nickel cobalt aluminate. The material is used as a high-voltage positive electrode material, and has the advantages of high energy density, high lithium ion conductivity and the like.
Optionally, in step S4, the corona discharge treatment time is 10-30S, the voltage is 10-40kV, and the frequency is 5-10kHZ. Applying a high-voltage high-frequency power supply of 10-40kV and 5-10kHZ on the electrode, generating a plasma atmosphere in the cavity, and directly or indirectly chemically reacting the plasma with the surface of the pressed high-voltage composite positive plate; and secondly, strong ion impact is generated by high-frequency pulse discharge, lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode materials can be removed rapidly and effectively, the corona discharge treatment time is 10-30S, the surface structures of the LLZO and the high-voltage positive electrode materials can be damaged obviously due to overlong time, the performance of the materials is not facilitated, and the residual lithium removal effect is not obvious due to overlong time.
Meanwhile, the application also provides a high-voltage composite positive plate, which is prepared by adopting the preparation method.
In addition, the application also provides an all-solid-state lithium battery, which comprises the high-voltage composite positive plate, the PEO-based polymer solid electrolyte and the negative plate, wherein the PEO-based polymer solid electrolyte is positioned between the high-voltage composite positive plate and the negative plate.
Optionally, the preparation method of the PEO-based polymer solid electrolyte is as follows: polyethylene oxide, lithium bis (trifluoromethanesulfonyl) imide and lithium perchlorate are mixed according to the molar ratio of 60-70:5-10:1-3 are dissolved in dimethyl sulfoxide and stirred for 3-5 hours at the temperature of 45-55 ℃ until the mixture is fully dissolved, thus obtaining a mixed solution; and then uniformly coating the mixed solution on the surface of a glass plate and curing to obtain the PEO-based polymer solid electrolyte. The PEO-based polymer solid electrolyte prepared by the above method is prepared by using lithium perchlorate (LiClO) 4 ) When contacting with the high-voltage composite positive plate, liClO 4 The composite anode plate can form a salt bridge with the W-LLZO nano material on the surface of the high-voltage composite anode plate, repair the interface crystal boundary of the high-voltage anode material and the polymer solid electrolyte, and play a role in optimizing the internal interface impedance of the battery.
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:
(1) The preparation method of the high-voltage composite positive plate provided by the embodiment of the application is simple in steps, and the W-LLZO nano material prepared by the application is higher in ceramic density and high in lithium ion conductivity compared with a pure lanthanum lithium zirconate LLZO nano material due to the fact that tungsten ions are doped. Meanwhile, the W-LLZO coated high-voltage positive electrode material prepared by the method has the advantages that the W-LLZO nano coating with high density is coated on the surface of the high-voltage positive electrode material, so that on one hand, the direct contact between the high-voltage positive electrode material and the polymer solid electrolyte is isolated, the catalysis is inhibited, and meanwhile, the transmission channel of lithium ions in positive electrode particles can be effectively ensured due to the fact that the W-LLZO has lithium ion conductivity. In addition, in consideration of the fact that the W-LLZO nano particles and the high-voltage positive electrode material are extremely easy to generate lithium carbonate impurities with low ion conductivity and low oxidation potential on the surfaces of the W-LLZO nano particles and the high-voltage positive electrode material during sintering, the method adopts a repeated pulse corona discharge method to treat the obtained high-voltage composite positive electrode plate, so that lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode material can be rapidly and effectively removed, lithium ion transmission characteristics are improved, interfacial gas precipitation is further restrained, and the method is high in efficiency, environment-friendly and free of third-party impurities. In a word, the high-voltage composite positive plate prepared by the method can effectively inhibit the catalytic effect of the high-voltage positive electrode material on the decomposition of the polymer solid electrolyte, improve the interface performance of the high-voltage positive electrode and the polymer solid electrolyte, reduce the gas production rate of the lithium battery in the charge-discharge cycle process, and greatly improve the safety of the battery.
(2) According to the preparation method of the high-voltage composite positive plate, in the step of preparing the W-LLZO coated high-voltage positive plate, the surface of the high-voltage positive plate can be uniformly coated with the W-LLZO nano coating layer by limiting parameters and the dosage of components, so that the direct contact between the high-voltage positive plate and the polymer solid electrolyte is effectively isolated, and the catalysis is inhibited. At the same time, adopt Li 4 SiO 4 Or Li (lithium) 2 ZrO is used as a sintering aid, so that on one hand, the sintering temperature is reduced, lithium loss in the sintering process is reduced, and meanwhile, the ionic conductivity of LLZO can be improved. From the results, the W-LLZO coated high-voltage positive electrode material prepared by the method can not onlyThe direct contact between the high-voltage positive electrode material and the polymer solid electrolyte is effectively isolated, the catalysis is inhibited, and the transmission channel of lithium ions in the positive electrode particles can be effectively ensured.
(3) According to the preparation method of the high-voltage composite positive plate, provided by the embodiment of the application, the corona discharge treatment time is limited to 10-30S, the voltage is 10-40kV, the frequency is 5-10kHZ, specifically, a high-voltage high-frequency power supply of 10-40kV and 5-10kHZ is applied to an electrode, a plasma atmosphere is generated in a cavity, and the plasma and the surface of the pressed high-voltage composite positive plate have direct or indirect chemical action; and secondly, strong ion impact is generated by high-frequency pulse discharge, lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode materials can be removed rapidly and effectively, the corona discharge treatment time is 10-30S, the surface structures of the LLZO and the high-voltage positive electrode materials can be damaged obviously due to overlong time, the performance of the materials is not facilitated, and the residual lithium removal effect is not obvious due to overlong time.
(4) According to the high-voltage composite positive plate, the catalytic process of the high-voltage positive electrode material on the decomposition and gas production of the polymer solid electrolyte can be effectively inhibited, the lithium ion transmission characteristic is improved, the separation of interfacial gas is further inhibited, the interfacial performance of the high-voltage positive electrode and the polymer solid electrolyte is effectively improved, the gas production rate of the solid lithium battery in the charge-discharge cycle process is further reduced, and the safety and reliability of the battery are improved.
(5) The all-solid-state lithium battery provided by the embodiment of the application can obviously reduce the gas production rate in the charge-discharge cycle process, and effectively improve the safety and reliability of the battery.
(6) In the preparation of PEO-based polymer solid electrolyte, the embodiment of the application provides an all-solid-state lithium battery, which adopts lithium perchlorate (LiClO 4 ) When contacting with the high-voltage composite positive plate, liClO 4 The composite anode plate can form a salt bridge with the W-LLZO nano material on the surface of the high-voltage composite anode plate, repair the interface crystal boundary of the high-voltage anode material and the polymer solid electrolyte, and play a role in optimizing the internal interface impedance of the battery.
Drawings
Fig. 1 is a schematic structural diagram of an all-solid-state lithium battery according to an embodiment of the present invention.
Detailed Description
For a further understanding of the present invention, the present invention will be described in detail with reference to the drawings and examples.
The present application is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be noted that, for convenience of description, only the portions related to the invention are shown in the drawings. The first, second, etc. words are provided for convenience in describing the technical scheme of the present invention, and have no specific limitation, and are all generic terms, and do not constitute limitation to the technical scheme of the present invention. It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
The application provides a preparation method of a high-voltage composite positive plate, which comprises the following steps:
s1, preparing a W-LLZO nano material: mixing LiOH, la (OH) 3, zrO2, WO3 and absolute ethyl alcohol, performing vibration ball milling, performing ball milling for 3-6 hours at normal temperature, and then sintering for 10-15 hours at 800-1000 ℃ to obtain a W-LLZO nano material with a cubic structure; wherein, liOH, la (OH) 3 、ZrO 2 And WO 3 The mass ratio of (2) is 6-8:2-4:1-3:0.05-0.09, the absolute ethyl alcohol accounts for 4-9% of the total mass, and the limitation of the parameter can ensure the synthesis of the W-LLZO nano material with strong cubic structure stability, high ceramic density and high ion conductivity, and can effectively compensate the lithium loss in the synthesis process. Meanwhile, the ball-to-material ratio in the vibration ball milling process is 20-40:60-80, wherein the limitation can improve the grinding efficiency and the grinding quality, and the grinding ball is any one of zirconia balls, alumina balls, stainless steel balls, zirconium silicate balls and nylon balls.
S2, preparing a W-LLZO coated high-voltage positive electrode material: mixing the W-LLZO nano material, the high-voltage positive electrode material and the sintering aid obtained in the step S1, performing vibration ball milling, and performing ball milling for 30-45min at normal temperature, wherein the mass ratio of the W-LLZO nano material to the high-voltage positive electrode material to the sintering aid is 3-8:55-70:1.5-3, the sintering aid is Li 4 SiO 4 Or Li (lithium) 2 ZrO 3 The high-voltage positive electrode material is one or more of lithium cobaltate, lithium nickel cobalt manganate and lithium nickel cobalt aluminate; then sintering the ball-milled mixed powder for 4-8 hours at the temperature of 550-800 ℃ in air to obtain a W-LLZO coated high-voltage positive electrode material; the W-LLZO coated high-voltage positive electrode material ensures that the surface of the high-voltage positive electrode material can be uniformly coated with a W-LLZO nano coating, thereby effectively isolating the direct contact between the high-voltage positive electrode material and the polymer solid electrolyte and inhibiting the catalysis. At the same time, adopt Li 4 SiO 4 Or Li (lithium) 2 ZrO is used as a sintering aid, so that on one hand, the sintering temperature is reduced, lithium loss in the sintering process is reduced, and meanwhile, the ionic conductivity of LLZO can be improved. In addition, the high-voltage positive electrode material has the advantages of high energy density, high lithium ion conductivity and the like.
In practical application, the nickel cobalt lithium manganate can be LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523)、LiNi 0.5 Co 0.2 Mn 0.2 O 2 (NCM622)、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)。
S3, preparing a high-voltage composite positive plate: and (3) transferring the W-LLZO coated high-voltage positive electrode material obtained in the step (S2) into a molybdenum alloy mold, and pressing at 100-300 standard atmospheric pressures to obtain the high-voltage composite positive electrode plate.
S4, treating the high-voltage composite positive plate obtained in the step S3 by adopting a repeated pulse corona discharge method, wherein the corona discharge treatment time is 10-30S, the voltage is 10-40kV, and the frequency is 5-10kHZ; specifically, a high-voltage high-frequency power supply of 10-40kV and 5-10kHZ is applied to the electrode, a plasma atmosphere is generated in the cavity, and the plasma and the surface of the pressed high-voltage composite positive plate have direct or indirect chemical action; and secondly, strong ion impact is generated by high-frequency pulse discharge, lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode materials can be removed rapidly and effectively, the corona discharge treatment time is 10-30S, the surface structures of the LLZO and the high-voltage positive electrode materials can be damaged obviously due to overlong time, the performance of the materials is not facilitated, and the residual lithium removal effect is not obvious due to overlong time.
Therefore, the W-LLZO nano material prepared by the method has the advantages that the stability of the cubic structure of the LLZO is improved compared with that of pure lanthanum lithium zirconate LLZO nano material due to the doping of tungsten ions, and the W-LLZO nano material has higher ceramic density and high lithium ion conductivity. Meanwhile, the W-LLZO coated high-voltage positive electrode material prepared by the method has the advantages that the W-LLZO nano coating with high density is coated on the surface of the high-voltage positive electrode material, so that on one hand, the direct contact between the high-voltage positive electrode material and the polymer solid electrolyte is isolated, the catalysis is inhibited, and meanwhile, the transmission channel of lithium ions in positive electrode particles can be effectively ensured due to the fact that the W-LLZO has lithium ion conductivity. In addition, in consideration of the fact that the W-LLZO nano particles and the high-voltage positive electrode material are extremely easy to generate lithium carbonate impurities with low ion conductivity and low oxidation potential on the surfaces of the W-LLZO nano particles and the high-voltage positive electrode material during sintering, the method adopts a repeated pulse corona discharge method to treat the obtained high-voltage composite positive electrode plate, so that lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode material can be rapidly and effectively removed, lithium ion transmission characteristics are improved, interfacial gas precipitation is further restrained, and the method is high in efficiency, environment-friendly and free of third-party impurities. In a word, the high-voltage composite positive plate prepared by the method can effectively inhibit the catalytic effect of the high-voltage positive electrode material on the decomposition of the polymer solid electrolyte, improve the interface performance of the high-voltage positive electrode and the polymer solid electrolyte, reduce the gas production rate of the lithium battery in the charge-discharge cycle process, and greatly improve the safety of the battery.
Meanwhile, the application also provides a high-voltage composite positive plate, which is prepared by adopting the preparation method, so that the catalytic process of the high-voltage positive plate material on the decomposition and gas production of the polymer solid electrolyte can be effectively inhibited, the lithium ion transmission characteristic is improved, the separation of interfacial gas is further inhibited, the interfacial performance of the high-voltage positive plate and the polymer solid electrolyte is effectively improved, the gas production rate of the solid lithium battery in the charge-discharge cycle process is further reduced, and the safety and reliability of the battery are improved.
In addition, the application also provides an all-solid-state lithium battery, which comprises the high-voltage composite positive plate, the PEO-based polymer solid electrolyte and the negative plate, wherein the PEO-based polymer solid electrolyte is positioned between the high-voltage composite positive plate and the negative plate; the all-solid-state lithium battery can obviously reduce the gas production rate in the charge-discharge cycle process and effectively improve the safety and reliability of the battery. The preparation method of the PEO-based polymer solid electrolyte comprises the following steps: polyethylene oxide, lithium bis (trifluoromethanesulfonyl) imide and lithium perchlorate are mixed according to the molar ratio of 60-70:5-10:1-3 are dissolved in dimethyl sulfoxide and stirred for 3-5 hours at the temperature of 45-55 ℃ until the mixture is fully dissolved, thus obtaining a mixed solution; and then uniformly coating the mixed solution on the surface of a glass plate, wherein the coating thickness is 50-250 mu m, and curing to obtain the PEO-based polymer solid electrolyte. The PEO-based polymer solid electrolyte adopts lithium perchlorate (LiClO) 4 ) When contacting with the high-voltage composite positive plate, liClO 4 Can form a salt bridge with W-LLZO nano material on the surface of the high-voltage composite positive plate to repair the high-voltage positive plate material and the high-voltage composite positive plateThe polymer solid electrolyte interface grain boundary plays a role in optimizing the internal interface impedance of the battery. Meanwhile, by limiting the coating thickness to 50-250 mu m, the energy density and the lithium ion transmission speed of the battery can be effectively ensured, the mechanical stability of an electrolyte membrane can be improved, and the safety and the selectivity of the solid battery can be improved. If the coating thickness is less than 50 μm, the mechanical strength of the electrolyte membrane layer is lowered, and the electrolyte membrane layer is easily bent and broken during the assembly and actual use of the battery, causing a short circuit of the solid battery, and lowering the safety of the battery. If the coating thickness is higher than 250 μm, the lithium ion transmission path increases significantly, resulting in an increase in internal resistance of the solid battery, and a decrease in power density of the battery.
Example 1
1. Preparing a high-voltage composite positive plate: liOH (99.99% by mass), la (OH) 3 (99.9% by mass), zrO 2 (99.99% by mass) and WO 3 (99.99% by mass) and absolute ethanol into a high-energy vibration ball mill, wherein LiOH and La (OH) 3 、ZrO 2 And WO 3 The mass ratio of (2) is 6:2:1:0.05, wherein the absolute ethyl alcohol accounts for 4% of the total mass, the grinding beads are zirconia balls, the ball-to-material ratio is 35:70, grinding is carried out for 4 hours at normal temperature, and then the balls are placed in a muffle furnace to be sintered for 13 hours at 920 ℃ to form the W-LLZO nano material with a cubic structure; next, the obtained W-LLZO nanomaterial was subjected to NCM523 (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ) And Li (lithium) 4 SiO 4 Adding the mixed powder into a high-energy vibration ball mill according to a mass ratio of 6:65:2.0, ball milling and mixing for 40min at normal temperature, sintering the mixed powder in air at 700 ℃ for 6h to obtain a W-LLZO coated high-pressure positive electrode material, transferring the W-LLZO coated high-pressure positive electrode material into a molybdenum alloy mold, and pressing the molybdenum alloy mold under 180 standard atmospheric pressures to obtain a high-pressure composite positive electrode sheet; finally, in order to remove lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode materials, a repeated pulse corona discharge method is adopted to treat the high-voltage composite positive electrode sheet, namely, a high-voltage high-frequency power supply of 35kV and 6kHZ is applied to an electrode, and the corona discharge treatment time is 25S.
2. PEO-based polymer solid electrolyte: polyethylene oxide PEO, lithium bis (trifluoromethanesulfonyl) imide LiTFSI andlithium perchlorate LiClO 4 The mixed solution is uniformly coated on the surface of a glass plate according to the mol ratio of 66:8:2, dissolved in dimethyl sulfoxide at 50 ℃, stirred for 4 hours until the mixed solution is fully dissolved, and the coating thickness is 120 mu m.
3. Assembling an all-solid-state lithium battery: the high-voltage composite positive electrode sheet and the lithium indium alloy sheet negative electrode sheet (the lithium atom percentage is 55%) prepared in the above way are respectively pressed at 60 standard atmospheric pressures on two sides of the PEO-based polymer solid electrolyte prepared in the way, and an all-solid lithium battery with the structure shown in figure 1 is prepared and comprises a negative electrode 1, a PEO-based polymer solid electrolyte 2, a positive electrode sheet 3 with holes, a gasket 4 with holes and a spring 5.
Example 2
1. Preparing a high-voltage composite positive plate: liOH (99.99% by mass), la (OH) 3 (99.9% by mass), zrO 2 (99.99% by mass) and WO 3 (99.99% by mass) and absolute ethanol into a high-energy vibration ball mill, wherein LiOH and La (OH) 3 、ZrO 2 And WO 3 The mass ratio of (2) is 7:3:2:0.07, wherein the absolute ethyl alcohol accounts for 6% of the total mass of the materials, the grinding beads are nylon balls, the ball-to-material ratio is 40:60, grinding is carried out for 6 hours at normal temperature, and then the materials are placed in a muffle furnace to be sintered for 10 hours at 1000 ℃ to form the W-LLZO nano material with a cubic structure; then the obtained W-LLZO nano material, lithium cobalt oxide LCO and Li 4 SiO 4 Adding the mixed powder into a high-energy vibration ball mill according to a mass ratio of 8:55:3, ball-milling and mixing for 45min at normal temperature, sintering the mixed powder in air at 550 ℃ for 4h to obtain a W-LLZO coated high-pressure positive electrode material, transferring the W-LLZO coated high-pressure positive electrode material into a molybdenum alloy mold, and pressing the high-pressure positive electrode material under 300 standard atmospheric pressures to obtain a high-pressure composite positive electrode sheet; finally, in order to remove lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode materials, a repeated pulse corona discharge method is adopted to treat the high-voltage composite positive electrode sheet, namely, a 40kV and 5kHZ high-voltage high-frequency power supply is applied to the electrode, and the corona discharge treatment time is 10S.
2. PEO-based polymer solid electrolyte: polyethylene oxide PEO, lithium bis (trifluoromethanesulfonyl) imide LiTFSI and lithium perchlorate LiClO 4 At a molar ratio of 60:10:3Dissolving in dimethyl sulfoxide at 55deg.C, stirring for 3 hr until it is fully dissolved, and uniformly coating the mixed solution on the surface of glass plate with a coating thickness of 250 μm.
3. Assembling an all-solid-state lithium battery: the high-voltage composite positive electrode sheet and the lithium indium alloy sheet negative electrode sheet (the lithium atom percentage is 60%) prepared in the above way are respectively pressed at 80 standard atmospheric pressures on two sides of the PEO-based polymer solid electrolyte prepared in the way, and an all-solid lithium battery with the structure shown in figure 1 is prepared and comprises a negative electrode 1, a PEO-based polymer solid electrolyte 2, a positive electrode sheet 3 with holes, a gasket 4 with holes and a spring 5.
Example 3
1. Preparing a high-voltage composite positive plate: liOH (99.99% by mass), la (OH) 3 (99.9% by mass), zrO 2 (99.99% by mass) and WO 3 (99.99% by mass) and absolute ethanol into a high-energy vibration ball mill, wherein LiOH and La (OH) 3 、ZrO 2 And WO 3 The mass ratio of (2) is 8:4:3:0.09, wherein the absolute ethyl alcohol accounts for 9 percent of the total mass, the grinding beads are stainless steel balls, the ball-to-material ratio is 20:80, grinding is carried out for 3 hours at normal temperature, and then the materials are placed in a muffle furnace to be sintered for 15 hours at 800 ℃ to form the W-LLZO nano material with a cubic structure; next, the obtained W-LLZO nanomaterial was subjected to NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) And Li (lithium) 4 SiO 4 Adding the mixed powder into a high-energy vibration ball mill according to a mass ratio of 3:70:1.5, ball milling and mixing for 30min at normal temperature, sintering the mixed powder in air at 800 ℃ for 4h to obtain a W-LLZO coated high-pressure positive electrode material, transferring the W-LLZO coated high-pressure positive electrode material into a molybdenum alloy mold, and pressing the high-pressure positive electrode material under 100 standard atmospheric pressures to obtain a high-pressure composite positive electrode plate; finally, in order to remove lithium carbonate impurities on the surfaces of the LLZO and the high-voltage positive electrode materials, a repeated pulse corona discharge method is adopted to treat the high-voltage composite positive electrode sheet, namely, a 40kV and 5kHZ high-voltage high-frequency power supply is applied to the electrode, and the corona discharge treatment time is 30S.
2. PEO-based polymer solid electrolyte: polyethylene oxide PEO, lithium bis (trifluoromethanesulfonyl) imide LiTFSI and lithium perchlorate LiClO 4 The molar ratio is 70:5:1 is dissolved in dimethyl sulfoxide at 45 ℃, stirred for 3 hours until the mixed solution is fully dissolved, and the mixed solution is uniformly coated on the surface of a glass plate, wherein the coating thickness is 50 mu m.
3. Assembling an all-solid-state lithium battery: and respectively pressing the prepared high-voltage composite positive plate and lithium indium alloy plate negative plate (the lithium atom percentage is 40%) at 40 standard atmospheric pressures on two sides of the prepared PEO-based polymer solid electrolyte to prepare the all-solid lithium battery with the structure shown in figure 1.
Comparative example 1
The difference compared to example 1 is that the high voltage positive electrode material used in comparative example 1 was pure NCM523, was not subjected to W-LLZO coating treatment, and the other conditions were the same as in example 1.
Comparative example 2
In comparison with example 1, the difference is that no LiClO was added in the preparation of the polymer electrolyte in comparative example 2 4 As salt bridge, the other conditions were the same as in example 1.
Comparative example 3
The difference compared with example 1 is that the high-voltage composite positive electrode sheet used in comparative example 3 was not subjected to corona discharge treatment, and the other conditions were the same as in example 1.
Comparative example 4
The difference compared with example 1 is that the polymer solid electrolyte coating thickness in comparative example 4 is 350 μm, and the other conditions are the same as in example 1.
Performance evaluation test of all-solid-state lithium battery
After the all-solid-state lithium batteries prepared in the examples 1-3 and the comparative examples 1-4 are connected as shown in fig. 1, gas generated in the charge and discharge process enters gas chromatography MASs spectrometry GC-MAS equipment along a vacuum pipeline, the gas volume generated by the battery in the charge and discharge process is monitored in real time, the gas generation speed is obtained, and the vacuum pipeline needs to be as short as possible in order to improve the accuracy of gas measurement; and the gas production rates of all solid-state lithium batteries prepared in examples 1 to 3 and comparative examples 1 to 4 in different voltage ranges were tested under the conditions of 60 ℃ with a discharge cut-off voltage of 2.7V and charge cut-off voltages of 3.7V, 3.9V, 4.1V, 4.3V and 4.5V, respectively, at 0.1 to 0.3C rate charge-discharge cycles, as shown in table 1.
Table 1: gas production rate of all solid-state lithium batteries of examples 1 to 3 and comparative examples 1 to 4 in different voltage ranges
As shown in Table 1, compared with comparative examples 1-4, the all-solid lithium battery using the high-voltage composite positive electrode sheet and/or the polymer solid electrolyte prepared by the method can effectively improve the interface performance of the high-voltage positive electrode and the polymer solid electrolyte, remarkably reduce the gas production rate in the charge-discharge cycle process and greatly improve the safety of the battery. Specifically, as can be seen from the results of example 1 and comparative example 1, the use of the W-LLZO coated high voltage cathode material significantly improved the interfacial stability between the high voltage cathode material and the polymer solid electrolyte, and increased the stable charging voltage to 4.3V. The specific mechanism is as follows: PEO begins to decompose under catalysis of high-voltage positive electrode material to generate free H + The free H+ results in the formation of extremely strong acidic HTFSI, which readily reacts with metallic lithium to form H when it migrates to the negative side of metallic lithium 2 . As the charge cutoff voltage increases, the positive electrode material surface activity increases, resulting in an increased gassing process. In the application, after the high-density W-LLZO nano coating is coated on the surface of the high-voltage positive electrode material, on one hand, the direct contact between the positive electrode material and the PEO-based polymer solid electrolyte is isolated, the catalysis is inhibited, and meanwhile, the W-LLZO has lithium ion conductivity, so that a lithium ion transmission channel in positive electrode particles is ensured.
Meanwhile, as can be seen from the results of example 1 and comparative example 2, the polymer solid electrolyte prepared in the present application was prepared by using LiClO 4 LiClO when the polymer solid electrolyte is contacted with the high-voltage composite positive electrode sheet 4 And a salt bridge is formed on the surface of the W-LLZO nano coating, so that the interface crystal boundary of the high-voltage anode material and the polymer solid electrolyte can be repaired, the interface impedance of the battery is optimized, and the performance of the solid battery is improved.
Furthermore, as can be seen from the results of example 1 and comparative example 3, the electric power was appliedAfter corona discharge treatment, lithium carbonate on the surfaces of the W-LLZO nano material and the high-voltage positive electrode material is effectively removed, so that Lewis acid-base action between the W-LLZO and PEO is enhanced, transmission of lithium ions at the interface between the positive electrode plate and the polymer solid electrolyte is improved, and H is effectively inhibited 2 Is precipitated.
Therefore, the high-voltage composite positive plate and/or the polymer solid electrolyte all-solid-state lithium battery prepared by the method can effectively improve the interface stability of the high-voltage positive plate material and the polymer solid electrolyte, improve an electrochemical window and provide effective technical support for developing the high-energy-density high-safety all-solid-state battery.
The invention and its embodiments have been described above by way of illustration and not limitation, and the invention is illustrated in the accompanying drawings and described in the drawings in which the actual structure is not limited thereto. Therefore, if one of ordinary skill in the art is informed by this disclosure, the structural mode and the embodiments similar to the technical scheme are not creatively designed without departing from the gist of the present invention.
Claims (7)
1. The preparation method of the high-voltage composite positive plate is characterized by comprising the following steps of:
s1, preparing a W-LLZO nano material: liOH, la (OH) 3 、ZrO 2 And WO 3 Mixing absolute ethyl alcohol, performing vibration ball milling, and then sintering to obtain a W-LLZO nano material with a cubic structure;
s2, preparing a W-LLZO coated high-voltage positive electrode material: mixing the W-LLZO nano material, the high-voltage positive electrode material and the sintering aid obtained in the step S1, performing vibration ball milling, and then sintering to obtain the W-LLZO coated high-voltage positive electrode material;
s3, preparing a high-voltage composite positive plate: carrying out mould pressing and pressing on the W-LLZO coated high-voltage positive electrode material obtained in the step S2 to obtain a high-voltage composite positive electrode plate;
s4, treating the high-voltage composite positive plate obtained in the step S3 by adopting a repeated pulse corona discharge method;
in the step S1, liOH, la (OH) 3 、ZrO 2 And WO 3 The mass ratio of (2) is 6-8:2-4:1-3:0.05-0.09, wherein the absolute ethyl alcohol accounts for 4-9% of the total mass of the material;
in the step S2, the ball milling time is 30-45min, and the mass ratio of the W-LLZO nano material to the high-voltage positive electrode material to the sintering aid is 3-8:55-70:1.5-3, the sintering aid is Li 4 SiO 4 Or Li (lithium) 2 ZrO 3 The method comprises the steps of carrying out a first treatment on the surface of the The sintering temperature is 550-800 ℃ and the sintering time is 4-8h;
in the step S4, the corona discharge treatment time is 10-30S, the voltage is 10-40kV, and the frequency is 5-10kHZ.
2. The method for preparing the high-voltage composite positive plate according to claim 1, wherein in the step S1, the ball milling time is 3-6 hours, the sintering temperature is 800-1000 ℃ and the sintering time is 10-15 hours.
3. The method for preparing the high-voltage composite positive plate according to claim 1 or 2, wherein in the step S1, the ball-to-material ratio in the vibration ball milling process is 20-40:60-80, wherein the grinding ball is selected from any one of zirconia balls, alumina balls, stainless steel balls, zirconium silicate balls and nylon balls.
4. The method for preparing a high-voltage composite positive electrode sheet according to claim 3, wherein in the step S2, the high-voltage positive electrode material is one or more of lithium cobaltate, lithium nickel cobalt manganate and lithium nickel cobalt aluminate.
5. The high-voltage composite positive plate is characterized in that the high-voltage composite positive plate is prepared by the preparation method of any one of claims 1-4.
6. An all-solid-state lithium battery comprising the high-voltage composite positive electrode sheet, the PEO-based polymer solid electrolyte, and the negative electrode sheet of claim 5, the PEO-based polymer solid electrolyte being located between the high-voltage composite positive electrode sheet and the negative electrode sheet.
7. The all-solid-state lithium battery according to claim 6, wherein the PEO-based polymer solid electrolyte is prepared by the following method: polyethylene oxide, lithium bis (trifluoromethanesulfonyl) imide and lithium perchlorate are mixed according to the molar ratio of 60-70:5-10:1-3 are dissolved in dimethyl sulfoxide and stirred for 3-5 hours at the temperature of 45-55 ℃ until the mixture is fully dissolved, thus obtaining a mixed solution;
and then uniformly coating the mixed solution on the surface of a glass plate and curing to obtain the PEO-based polymer solid electrolyte.
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| 核壳结构富锂锰基层状正极材料的研究;胡思江;《中国博士学位论文全文数据库 工程科技Ⅱ辑》;第四章 * |
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