CN116525767A - Lithium-rich positive electrode plate, preparation method thereof and lithium ion battery - Google Patents
Lithium-rich positive electrode plate, preparation method thereof and lithium ion battery Download PDFInfo
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- CN116525767A CN116525767A CN202210879592.3A CN202210879592A CN116525767A CN 116525767 A CN116525767 A CN 116525767A CN 202210879592 A CN202210879592 A CN 202210879592A CN 116525767 A CN116525767 A CN 116525767A
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 237
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 48
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 48
- 238000002360 preparation method Methods 0.000 title abstract description 16
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- 229910021102 Li0.5La0.5TiO3 Inorganic materials 0.000 description 2
- 229910009274 Li1.4Al0.4Ti1.6 (PO4)3 Inorganic materials 0.000 description 2
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- ISJNWFZGNBZPQE-UHFFFAOYSA-N germanium;sulfanylidenesilver Chemical compound [Ge].[Ag]=S ISJNWFZGNBZPQE-UHFFFAOYSA-N 0.000 description 2
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- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 1
- 125000003184 C60 fullerene group Chemical group 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
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- XMSXQFUHVRWGNA-UHFFFAOYSA-N Decamethylcyclopentasiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1 XMSXQFUHVRWGNA-UHFFFAOYSA-N 0.000 description 1
- 229910021617 Indium monochloride Inorganic materials 0.000 description 1
- 239000005279 LLTO - Lithium Lanthanum Titanium Oxide Substances 0.000 description 1
- 229910009265 Li1.4Al0.4Ge1.6(PO4)3 Inorganic materials 0.000 description 1
- 229910005317 Li14Zn(GeO4)4 Inorganic materials 0.000 description 1
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- 229910006406 SnO 2 At Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- PFYQFCKUASLJLL-UHFFFAOYSA-N [Co].[Ni].[Li] Chemical compound [Co].[Ni].[Li] PFYQFCKUASLJLL-UHFFFAOYSA-N 0.000 description 1
- QRVIVVYHHBRVQU-UHFFFAOYSA-H [Li+].[V+5].[O-]P([O-])(F)=O.[O-]P([O-])(F)=O.[O-]P([O-])(F)=O Chemical compound [Li+].[V+5].[O-]P([O-])(F)=O.[O-]P([O-])(F)=O.[O-]P([O-])(F)=O QRVIVVYHHBRVQU-UHFFFAOYSA-H 0.000 description 1
- YWJVFBOUPMWANA-UHFFFAOYSA-H [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O Chemical compound [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O YWJVFBOUPMWANA-UHFFFAOYSA-H 0.000 description 1
- PAHNBNDPQWLRQX-UHFFFAOYSA-N [N].[O].[P].[Li] Chemical compound [N].[O].[P].[Li] PAHNBNDPQWLRQX-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
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- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229940086555 cyclomethicone Drugs 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
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- 230000003628 erosive effect Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- MDQRDWAGHRLBPA-UHFFFAOYSA-N fluoroamine Chemical compound FN MDQRDWAGHRLBPA-UHFFFAOYSA-N 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
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- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 description 1
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- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 description 1
- APHGZSBLRQFRCA-UHFFFAOYSA-M indium(1+);chloride Chemical compound [In]Cl APHGZSBLRQFRCA-UHFFFAOYSA-M 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
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- 239000011244 liquid electrolyte Substances 0.000 description 1
- BDKWOJYFHXPPPT-UHFFFAOYSA-N lithium dioxido(dioxo)manganese nickel(2+) Chemical compound [Mn](=O)(=O)([O-])[O-].[Ni+2].[Li+] BDKWOJYFHXPPPT-UHFFFAOYSA-N 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- DVATZODUVBMYHN-UHFFFAOYSA-K lithium;iron(2+);manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[Fe+2].[O-]P([O-])([O-])=O DVATZODUVBMYHN-UHFFFAOYSA-K 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
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- 239000011859 microparticle Substances 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 150000001282 organosilanes Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
-
- 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
- H01M2004/028—Positive 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to the field of lithium ion battery anodes, in particular to a lithium-rich anode plate, a preparation method thereof and a lithium ion battery. The lithium-rich positive electrode plate comprises a current collector, a lithium-rich material layer formed on the current collector and a protective layer formed on the lithium-rich material layer; the protective layer comprises a solid protective material and a pore repairing agent. The lithium-rich positive electrode plate provided by the invention is provided with the protective layer, and the protective layer can play a role in protecting the electrode plate, so that the storage life is prolonged, the storage cost is reduced, and the performance of the battery is improved. Experiments show that the protective layer can effectively isolate carbon dioxide and water vapor in the air, and the overall stability of the electrode plate is improved; in the process of charging and discharging the battery, the protective layer can protect the surface of the positive electrode side, inhibit the phenomenon that metal is easy to dissolve out of the positive electrode, and not influence the intercalation and deintercalation of lithium ions in the positive electrode material, so that the self-discharging, the cycle life and the charging and discharging efficiency of the battery are improved.
Description
Technical Field
The invention relates to the field of lithium ion battery anodes, in particular to a lithium-rich anode plate, a preparation method thereof and a lithium ion battery.
Background
The lithium ion battery has the advantages of high working voltage, long cycle life, high energy density, no memory effect and the like, and can be rapidly applied to the fields of mobile communication, notebook computers and the like after being put into the market in 1991. The lithium ion battery mainly comprises a positive electrode, a negative electrode, electrolyte and a diaphragm, wherein the charging and discharging process of the lithium ion battery is the process of deintercalation and intercalation of lithium ions in the positive electrode and the negative electrode.
The positive electrode of a lithium ion battery is the only (or primary) provider of lithium ions in a lithium ion battery and generally comprises an active material, a conductive agent, a binder and a current collector. The current improvement on the positive electrode of the lithium ion battery generally comprises modification of an active material, structural improvement of a current collector and the like, but the improvement on the positive electrode of the lithium ion battery is seldom performed from the protection perspective.
The current manufacturing process of the lithium-rich positive electrode plate in the lithium ion battery generally comprises the steps of firstly preparing slurry with certain viscosity from positive electrode active microparticles, a lithium supplementing additive, a conductive agent and a binder in an NMP (N-methylpyrrolidone) solvent. And coating the slurry on an aluminum foil, drying, rolling and cutting to obtain the required lithium-rich positive plate. Although the method is a general technology in the industry, the technology has certain defects that the surface of the electrode plate is not provided with a protective layer, and in an environment with certain humidity, the electrode plate can react with water in the air, so that the electrode plate is deteriorated and loses efficacy, and the service life of the electrode plate is seriously influenced. In order to store the electrode sheet for a long time, there is a high requirement on the environment in which the electrode sheet is stored, which in turn increases the storage cost of the electrode sheet.
Disclosure of Invention
In view of the above, the technical problem to be solved by the invention is to provide a lithium-rich positive electrode plate, a preparation method thereof and a lithium ion battery.
The invention provides a lithium-rich positive electrode plate, which comprises a current collector, a lithium-rich material layer formed on the current collector and a protective layer formed on the lithium-rich material layer, wherein the protective layer is formed on the lithium-rich material layer; the protective layer comprises a solid protective material and a pore repairing agent.
Specifically, the protective layer takes the solid protective material as a main constituent material, and pores are formed among the solid protective material in consideration of the fact that the solid protective material forms the protective layer, so that the protective layer is filled with a pore repairing agent; the pore repairing agent can fill pores formed between solid protection materials, and the water vapor prevention capability of the protection layer is enhanced. In certain embodiments of the invention, the pore-modifying agent fills at least one of the pores formed between the solid protective materials or is sealed at the openings of the pores. After the invention is applied to the battery, the pore repairing agent can be separated from the pores or can be dissolved in the electrolyte in the use process of the battery, and the protective layer is used for thoroughly isolating the pole piece from being contacted with water in the air, so that the pore repairing agent can be present or absent after the pore repairing agent is applied to the battery and used.
More specifically, at least one of the solid protective material and the pore-repairing agent of the present invention has hydrophobicity. The material forming the protective layer has hydrophobicity, so that the protective layer also has hydrophobicity, moisture in air is better isolated, and the erosion effect of the moisture on the protective layer is reduced.
In certain embodiments of the present invention, the pore-modifying agent is at least one of a solid pore-modifying agent or a liquid pore-modifying agent; the liquid state of the liquid crystal Kong Jicheng is that the solid crystal pore-repairing agent is in a solid or semi-solid state, and the solid crystal pore-repairing agent is made of the same material and has different molecular weights and different forms. When the pore-repairing agent is a solid pore-repairing agent, the physical properties of the solid pore-repairing agent, such as particle size, molecular weight and the like, have different influences on the effect of filling the pores and the protection effect after filling. When the particle size of the solid pore-repairing agent is too large, the filling effect is poor, and when the particle size of the solid pore-repairing agent is too small, the solid pore-repairing agent is easy to agglomerate and difficult to disperse, and is generally about the particle size of the positive electrode material; when the molecular weight of the solid pore-repairing agent is too small, the strength is reduced, and when the molecular weight is too large, the viscosity of the slurry is increased, so that the thickness of the prepared positive plate is uneven, and the performance of the battery is affected. In some embodiments, the solid pore former has a particle size of 0.01nm to 3 μm, preferably 1nm to 2 μm, more preferably 20nm. In some embodiments, the molecular weight of the solid pore former is 40000Da to 500000Da, preferably 80000Da.
When the pore repairing agent is a liquid pore repairing agent, pores formed among solid protective materials can be filled more favorably, a better protective effect is achieved, and physical properties of the liquid pore repairing agent such as molecular weight and evaporation temperature have different influences on the effect of filling the pores and the protective effect after filling. When the molecular weight of the pore-repairing agent is too large, the filling speed is low, and the filling effect is poor; when the molecular weight of the pore-repairing agent is too small, it is easily volatilized. When the evaporation temperature of the pore repairing agent is too low, the pore repairing agent is easy to evaporate in the subsequent treatment process, and the protective effect is lost. In some embodiments, the molecular weight of the liquid pore-modifying agent is 70Da to 20000Da, preferably 161.12Da. In some embodiments, the evaporation temperature of the liquid pore repair agent is from 90 ℃ to 300 ℃, preferably from 130 ℃ to 300 ℃, more preferably 190 ℃.
In certain embodiments of the present invention, the pore-modifying agent is selected from one or more of a polyolefin, a fluoroamine, an ester, a nitrile, a perfluoroalkyl methacrylic polymer, a polyorganosiloxane, or an organosilane. In some embodiments, the solid pore-modifying agent is selected from one or more of polyethylene, polybutylene, polypropylene, polydimethylsiloxane, 4-trifluoromethylaniline, perfluoroalkyl ethyl methacrylate, or cyclomethicone. In certain embodiments of the present invention, the pore-modifying agent may also be selected from one or more of PE-PP copolymers, polyethylene oxide based polymers, polysiloxane based polymers, and aliphatic polycarbonate based polymers. In some embodiments, the pore-modifying agent may also be selected from one or more of polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polyvinyl alcohol.
In certain embodiments of the present invention, the solid protective material is selected from at least one of an ion-conductive material or an electron-conductive material. The solid protection material is a main material of the protection layer, the material selection of the solid protection material can influence the performance of the pole piece, the ion conductivity of the pole piece can be further improved by taking the ion conductive material as the solid protection material to form the protection layer, the electron conductivity of the pole piece can be further improved by taking the electron conductive material as the solid protection material to form the protection layer, meanwhile, the ion conductivity material and the electron conductivity material can play a role in enhancing compactness by taking the ion conductive material and the electron conductivity material as the solid protection material, and the compactness of the protection layer is improved and the ion and electron conductivity performance of the protection layer are improved.
In certain embodiments of the present invention, the solid protective material is selected from one or more of a perovskite-type solid protective material, a NASICON-type solid protective material, a garnet-type solid protective material, or a conductive metal oxide-type solid protective material; the perovskite type solid protection material, the NASICON type solid protection material and the garnet type solid protection material all belong to ion conductive materials, and the conductive metal oxide type solid protection material belongs to electron conductive materials.
Wherein the perovskite type solid protection material comprises Li 3x La 2/3 -xTiO 3 LLTO, specifically comprising Li 0.5 La 0.5 TiO 3 、Li 0.33 La 0.57 TiO 3 、Li 0.29 La 0.57 TiO 3 、Li 0.33 Ba 0.25 La 0.39 TiO 3 、(Li 0.33 La 0.56 ) 1.005 Ti 0.99 Al 0.01 O 3 Or Li (lithium) 0.5 La 0.5 Ti 0.95 Zr 0.05 O 3 At least one of (a) and (b);
the NASICON type solid protection material comprises Li 1+x Al x Ti 2-x (PO 4 ) 3 Or Li (lithium) 1+x Al x Ge 2-x (PO 4 ) 3 The Li is 1+x Al x Ti 2-x (PO 4 ) 3 Comprises Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 LATP for short; the Li is 1+x Al x Ge 2-x (PO 4 ) 3 Comprises Li 1.4 Al 0.4 Ge 1.6 (PO 4 ) 3 。
The garnet type solid protection material comprises Li 7 La 3 Zr 2 O 12 、Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 Or Li (lithium) 6.5 La 3 Zr 1.5 Ta 0.5 O 12 At least one of the Li 7 La 3 Zr 2 O 12 Simply referred to as LLZO.
The conductive metal oxide solid protection material comprises In 2 O 3 ZnO or SnO 2 At least one of them.
In certain embodiments of the present invention, the solid protective material may also be selected from one or more of LISICON-type solid protective materials, thio-LISICON-type solid protective materials, sulfur silver germanium ore-type sulfide solid protective materials, halide solid protective materials, garnet-type solid protective materials, anti-perovskite-type solid protective materials, or lithium phosphorus oxygen nitrogen solid protective materials. In some embodiments, the LISICON-type solid protective material comprises Li 14 Zn-(GeO 4 ) 4 、Li 4 SiO 4 、Li 4 ScO 4 、Li 4 GeO 4 、Li 4 TiO 4 、Li 3 PO 4 、Li 3 AsO 4 、Li 3 VO 4 、Li 3 CrO 4 、γ-Li 3 PO 4 、Li 9.4 Si 1.74 P 1.44 S 11.7 Cl 0.3 、Li 11-x M 2-x P 1+x S 12 Or Li (lithium) 10±1 MP 2 X 12 At least one of (a) and (b); wherein saidLi 11-x M 2- x P 1+x S 12 M in (a) is Ge, sn or Si, 0.ltoreq.x.ltoreq.1, e.g. Li 10 GeP 2 S 12 Or Li (lithium) 10 SnP 2 S 12 Or Li (lithium) 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 The method comprises the steps of carrying out a first treatment on the surface of the The Li is 10±1 MP 2 X 12 M in (C) is Ge, si, sn, al or P, X is O, S or Se. In some embodiments, the Thio-LISICON-type solid protective material comprises (100-x) Li 2 S-xP 2 S 5 ，0<x<100; or Li (lithium) 4-x Ge 1- x P x S 4 ，0<x<1, a step of; or Li (lithium) 4 SnS 4 At least one of them. In some embodiments, the sulfur silver germanium ore type sulfide solid protection material includes Li 6 PS 5 Cl、Li 6 PS 5 Br or Li 6 PS 5 At least one of I; in some embodiments, the halide solid protective material comprises: li (Li) 3 InCl 6 Or Li (lithium) 3 YBr 6 . In some embodiments, the Garnet-type solid protective material comprises Li 5 La 3 Ta 2 O 12 Or Li (lithium) 7 La 3 Zr 2 O 12 The Li is 7 La 3 Zr 2 O 12 Simply referred to as LLZO. In some embodiments, the anti-perovskite solid protection material comprises Li 3-2x M x HalO, where M is typically a cation of valence > 2, such as Mg, ca or Ba, and where Hal is a halide such as Cl, I or mixtures thereof.
In some embodiments, the solid protective material is selected from Li 0.5 La 0.5 TiO 3 、Li 0.33 La 0.57 TiO 3 、Li 0.29 La 0.57 TiO 3 、Li 0.33 Ba 0.25 La 0.39 TiO 3 、(Li 0.33 La 0.56 ) 1.005 Ti 0.99 Al 0.01 O 3 、Li 0.5 La 0.5 Ti 0.95 Zr 0.05 O 3 、Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 、Li 7 La 3 Zr 2 O 12 、Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 Or Li (lithium) 6.5 La 3 Zr 1.5 Ta 0.5 O 12 One or more of the following.
When the content of the pore-repairing agent in the protective layer is too high, the pole piece is unstable, and when the content of the pore-repairing agent is too low, the material in the lithium-rich positive pole piece is not well protected, so that the release of lithium ions is influenced, and the storage life of the pole piece is not prolonged. In some embodiments, the pore-modifying agent is present in the protective layer in an amount of 10ppm to 8000ppm by mass, preferably 90ppm to 8000ppm by mass, more preferably 90ppm to 5000ppm by mass, more preferably 90ppm to 3000ppm by mass, and even more preferably 90ppm to 1000ppm by mass.
The protective layer has a certain thickness, and can not play a role in protection when the thickness is too thin; when the thickness is too thick, the transmission of lithium ions is affected; the proper thickness is selected to facilitate the transmission of lithium ions in the pores, to facilitate better embedding of particles in the active layer into the protective layer, and to improve the cycle performance and energy density of the battery. In some embodiments, the protective layer has a thickness of 1nm to 20 μm, preferably 1nm to 15 μm, more preferably 1nm to 1 μm, more preferably 1nm to 500nm, more preferably 1nm to 200nm, more preferably 1nm to 100nm, more preferably 10nm to 50nm, and most preferably 20nm to 30nm.
The protective layer and the positive electrode matrix have a certain proportion relation, and if the content of the protective layer is too much, the cost is increased due to the weight of the pole piece; if the content of the protective layer is too small, the pole piece cannot be uniformly protected. In some embodiments, the mass ratio of the protective layer to the positive electrode substrate is 0.1wt% to 15wt%; preferably 0.5 to 10wt%, more preferably 1 to 10wt%, even more preferably 1 to 7wt%, and even more preferably 1 to 5wt%.
In certain embodiments of the present invention, the lithium-rich material layer includes a positive electrode active material and a lithium-containing metal compound. Specifically, the lithium-rich material layer comprises a lithium-rich material, wherein the lithium-rich material comprises a positive electrode active material and a lithium-containing metal compound; the lithium-containing metal compound may be defined as a lithium-supplementing material (lithium-containing metal compound) or some lithium-containing metal compounds may be used as a lithium-rich positive electrode material in the case of a lithium-rich material. The current collector is not particularly limited in the present invention, and a current collector well known to those skilled in the art may be used.
The positive electrode active material is a common positive electrode active material of a lithium ion battery; in some embodiments, the positive active material is selected from one or more of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, lithium vanadium fluorophosphate, lithium titanate, lithium nickel manganate, lithium nickel cobalt aluminate.
The lithium-containing metal compound of the invention is Li x M y O z Wherein x is more than 0 and less than or equal to 6, y is more than 0 and less than or equal to 3, z is more than 0 and less than or equal to 4, and M comprises one or more of Fe, co, ni, mn, V, cu, mo, al, ti, mg, zr.
The lithium-containing metal compounds of the present invention include a wide variety of lithium-supplementing agents, some of which can be used as positive electrode active materials, and some of which can be used as lithium-rich positive electrode materials, and are mainly determined by the structure of the lithium-containing metal compounds. Such as Li 5 FeO 4 In the charge and discharge process, after lithium ions are released, the structure collapses, so that the released lithium ions serve as sacrificial lithium, and an SEI film is formed on the surface of the negative electrode. Such as Li 2 NiO 2 The lithium-rich cathode material can be used as a lithium supplementing agent, and can be used as the lithium supplementing agent of the cathode active material when a small amount of the lithium-rich cathode material is compounded with other cathode active materials; when the lithium-rich cathode material is used as a lithium-rich cathode material and is compounded with other cathode active materials to form a whole, the lithium-rich cathode material is equivalent to another cathode active material under the whole, and after the lithium is released by the cathode active material, the structure is converted into a layered structure from an oblique square phase, so that part of lithium can participate in forming an SEI film and is irreversible, and part of lithium can return to the layered structure again.
The invention provides a preparation method of the lithium-rich positive plate, which comprises the following steps:
coating the lithium-rich material layer on the current collector, mixing the solid protection material and the pore-repairing agent, and coating the mixture on the lithium-rich material layer to prepare a lithium-rich positive plate;
or alternatively, the process may be performed,
coating the lithium-rich material layer on the current collector, coating the solid protection material on the lithium-rich material layer, and then coating a pore-repairing agent to prepare a lithium-rich positive plate;
or alternatively, the process may be performed,
coating the lithium-rich material layer on the current collector, coating the pore-repairing agent on the lithium-rich material layer, and then coating a solid protective material to prepare a lithium-rich positive electrode plate;
or alternatively, the process may be performed,
and mixing the lithium-rich material layer, the solid protective material and the pore-repairing agent, and coating the mixture on the current collector to prepare the lithium-rich positive electrode plate.
In some embodiments of the present invention, the lithium-rich material layer is coated on the current collector, and the solid protection material and the pore-repairing agent are mixed and then coated on the lithium-rich material layer, so as to prepare the lithium-rich positive electrode sheet. Specifically, mixing a positive electrode active material and a lithium-containing metal compound, and then coating the mixture on the current collector to obtain a lithium-rich material layer formed on the current collector; and mixing the solid protection material with a pore repairing agent, and coating the mixture on the surface of the lithium-rich material layer to prepare the lithium-rich positive electrode plate. In some embodiments, the positive electrode active material and the lithium-containing metal compound are mixed, coated on the surface of a current collector, and dried to obtain a lithium-rich material layer formed on the current collector; and mixing the solid protective material with the pore repairing agent, coating the mixture on the surface of the lithium-rich material layer, drying, transferring the pore repairing agent into pores formed between the solid protective materials in the drying process, and rolling after the drying process to obtain the lithium-rich positive electrode plate. In some embodiments, the temperature of the drying process is 80 ℃ to 120 ℃ and the time of the drying process is 20 hours to 24 hours.
In some embodiments of the present invention, the lithium-rich material layer is coated on the current collector, and the solid protection material is coated on the lithium-rich material layer, and then the pore-repairing agent is coated, so as to obtain the lithium-rich positive electrode sheet. Specifically, mixing a positive electrode active material and a lithium-containing metal compound, and then coating the mixture on the current collector to obtain a lithium-rich material layer formed on the current collector; and coating a solid protective material on the surface of the lithium-rich material layer, and then coating a pore-repairing agent to prepare the lithium-rich positive electrode plate. In some embodiments, the positive electrode active material and the lithium-containing metal compound are mixed and then coated on the current collector, and drying treatment is performed to obtain a lithium-rich material layer formed on the current collector; and coating a solid protective material on the surface of the lithium-rich material layer, coating a pore-repairing agent on the lithium-rich material layer coated with the solid protective material, transferring the pore-repairing agent into pores formed between the solid protective materials in the drying treatment and drying treatment process, and rolling after the drying treatment to obtain the lithium-rich positive plate. In some embodiments, the temperature of the drying process is 80 ℃ to 120 ℃ and the time of the drying process is 20 hours to 24 hours.
In some embodiments of the present invention, the lithium-rich material layer is coated on the current collector, and the pore-repairing agent is coated on the lithium-rich material layer, and then the solid protection material is coated, so as to obtain the lithium-rich positive electrode plate. Specifically, mixing a positive electrode active material and a lithium-containing metal compound, and then coating the mixture on the current collector to obtain a lithium-rich material layer formed on the current collector; and coating a pore-repairing agent on the surface of the lithium-rich material layer, and then coating a solid protective material to prepare the lithium-rich positive electrode plate. In some embodiments, the positive electrode active material and the lithium-containing metal compound are mixed and then coated on the current collector, and drying treatment is performed to obtain a lithium-rich material layer formed on the current collector; and coating the pore-repairing agent on the surface of the lithium-rich material layer, coating a solid protective material on the lithium-rich material layer coated with the pore-repairing agent, drying, floating the pore-repairing agent into pores formed among the solid protective materials in the drying process, and rolling after the drying process to obtain the lithium-rich positive plate. In some embodiments, the temperature of the drying process is 80 ℃ to 120 ℃ and the time of the drying process is 20 hours to 24 hours.
In some embodiments of the present invention, the lithium-rich material layer, the solid protection material and the pore-repairing agent are mixed and coated on the current collector, so as to prepare the lithium-rich positive electrode sheet. Specifically, the lithium-containing metal compound, the positive electrode active material, the solid protection material and the pore-repairing agent are mixed and coated on the current collector to prepare the lithium-rich positive electrode plate. In some embodiments, a lithium-containing metal compound and a positive electrode active material are mixed, then a solid protective material and a pore-repairing agent are added, then N-methylpyrrolidone (NMP), a binder and a conductive agent are added, and after mixing, the mixture is subjected to homogenization, coating on a current collector, drying treatment and cutting to obtain a lithium-rich positive electrode sheet. In some embodiments, the temperature of the drying process is 80 ℃ to 120 ℃ and the time of the drying process is 20 hours to 24 hours.
In some embodiments, a lithium-containing metal compound and a positive electrode active material are mixed, and then a solid protective material, a pore-repairing agent, N-methylpyrrolidone (NMP), a binder and a conductive agent are added, and after mixing, the mixture is subjected to homogenization, coating on a current collector, drying treatment and cutting to obtain a lithium-rich positive electrode sheet. In some embodiments, the binder is selected from one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives. In some embodiments, the conductive agent is selected from one or more of graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotubes. In some embodiments, the temperature of the drying process is 80 ℃ to 120 ℃ and the time of the drying process is 20 hours to 24 hours.
The invention also provides a lithium ion battery, which comprises the lithium-rich positive electrode plate or the lithium-rich positive electrode plate obtained by the preparation method. Specifically, the lithium ion battery provided by the invention is a secondary battery, and comprises a positive electrode, a negative electrode and a diaphragm overlapped between the positive electrode and the negative electrode, wherein the positive electrode comprises the lithium-rich positive electrode plate or the lithium-rich positive electrode plate obtained by the preparation method. In certain embodiments of the invention, the lithium ion battery is a solid state lithium secondary battery or a liquid electrolyte lithium secondary battery.
The lithium-rich positive electrode plate comprises a current collector, a lithium-rich material layer formed on the current collector and a protective layer formed on the lithium-rich material layer; the protective layer comprises a solid protective material and a pore repairing agent. The lithium-rich positive electrode plate provided by the invention is provided with the protective layer which is formed by the solid protective material and contains the pore-repairing agent for filling, the preparation process of the protective layer is simple, the electrode plate can be effectively protected from being influenced by water vapor in the air after being filled by the pore-repairing agent, the storage life of the electrode plate is prolonged, the storage cost of the electrode plate is reduced, the prepared battery has good charge and discharge performance and high stability, and the performance of the electrode plate can still be fully volatilized after long-time storage. Experiments show that the lithium ion battery with the protective layer has higher gram specific capacity for the first time and higher capacity retention rate after 1C multiplying power circulation for 200 circles than the lithium ion battery without the protective layer, and the protective layer can effectively isolate carbon dioxide and water vapor in the air, so that the overall stability of the electrode plate is improved; in the process of charging and discharging the battery, the protective layer can protect the surface of the positive electrode side, inhibit the phenomenon that metal is easy to dissolve out of the positive electrode, and not influence the intercalation and deintercalation of lithium ions in the positive electrode material, so that the self-discharging, the cycle life and the charging and discharging efficiency of the battery are improved.
Drawings
Fig. 1 is a schematic diagram of the structure of the lithium-rich positive electrode sheet of the present invention.
Detailed Description
The invention discloses a lithium-rich positive plate, a preparation method thereof and a lithium ion battery. Those skilled in the art can, with the benefit of this disclosure, suitably modify the process parameters to achieve this. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that the invention can be practiced and practiced with modification and alteration and combination of the methods and applications herein without departing from the spirit and scope of the invention.
The structure of the lithium-rich positive pole piece is shown in fig. 1, and fig. 1 is a schematic diagram of the structure of the lithium-rich positive pole piece; in fig. 1, 1 is a current collector, 2 is a lithium-rich material layer, 3 is a protective layer, 31 is a solid protective material, and 32 is a pore-repairing agent.
The invention is further illustrated by the following examples:
example 1
S1: to lithium-containing metal compound Li 5 FeO 4 And a positive electrode active material LiFePO 4 And uniformly mixing according to the mass ratio of 5:95 to obtain the lithium-rich material.
S2: adding 0.1wt% of Li to the lithium-rich material obtained in the step S1 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 And adding 90ppm of polyethylene pore-repairing agent into the solid protective material (LATP) according to the mass of the added solid protective material, and uniformly mixing to obtain the lithium-rich material mixed with the protective layer material. Wherein the grain diameter of the polyethylene pore-repairing agent is 30nm, and the molecular weight is 20 ten thousand Da.
S3: mixing the lithium-rich material mixed with the protective layer material obtained in the steps of N-methylpyrrolidone (NMP) and S2, super P conductive agent and polyvinylidene fluoride (PVDF) according to the mass ratio of 100:95:2:3, wherein the mixing mode is ball milling, the ball milling time is 60min, the rotating speed is set to be 30Hz, the lithium-rich positive plate is prepared through homogenizing, coating, drying and cutting, the lithium-rich positive plate is baked in a vacuum oven at the temperature of 100 ℃, and the baking treatment time is 20h, so that trace water in the lithium-rich positive plate is removed.
Through testing, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 90nm.
Example 2
S1: to lithium-containing metal compound Li 2 NiO 2 And a positive electrode active material LiFePO 4 And uniformly mixing according to the mass ratio of 5:95 to obtain the lithium-rich material.
S2: to the lithium-rich material obtained in S1Adding Li accounting for 0.1 weight percent of the lithium-rich material 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 And adding 90ppm of polyethylene pore-repairing agent into the solid protective material (LATP) according to the mass of the added solid protective material, and uniformly mixing to obtain the lithium-rich material mixed with the protective layer material. Wherein the grain diameter of the polyethylene pore-repairing agent is 30nm, and the molecular weight is 20 ten thousand Da.
S3: mixing the lithium-rich material mixed with the protective layer material obtained in the NMP and the S2, super P and PVDF according to the mass ratio of 100:95:2:3, wherein the mixing mode is ball milling, the ball milling time is 60min, the rotating speed is set to be 30Hz, the lithium-rich positive plate is prepared through homogenating, coating, drying and cutting operations, the lithium-rich positive plate is baked in a vacuum oven at 100 ℃, and the baking treatment time is 22h, so that trace water in the lithium-rich positive plate is removed.
Through testing, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 122nm.
Example 3
S1: to lithium-containing metal compound Li 5 FeO 4 And a positive electrode active material LiFePO 4 And uniformly mixing according to the mass ratio of 5:95 to obtain the lithium-rich material.
S2: adding Li accounting for 5 weight percent of the lithium-rich material into the lithium-rich material obtained in the step S1 0.5 La 0.5 TiO 3 And adding 1000ppm of polypropylene pore-repairing agent into the solid protective material according to the mass of the added solid protective material, and uniformly mixing to obtain the lithium-rich material mixed with the protective layer material. Wherein the particle size of the polypropylene pore-repairing agent is 29nm, and the molecular weight is 8 ten thousand Da.
S3: mixing the lithium-rich material mixed with the protective layer material obtained in the NMP and the S2, super P and PVDF according to the mass ratio of 100:95:2:3, wherein the mixing mode is ball milling, the ball milling time is 60min, the rotating speed is set to be 30Hz, the lithium-rich positive plate is prepared through homogenating, coating, drying and cutting operations, the lithium-rich positive plate is baked in a vacuum oven at 110 ℃, and the baking treatment time is 21h, so that trace water in the lithium-rich positive plate is removed.
Through test, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 350nm.
Example 4
S1: to lithium-containing metal compound Li 5 FeO 4 And a positive electrode active material LiFePO 4 And uniformly mixing according to the mass ratio of 5:95 to obtain the lithium-rich material.
S2: adding 7wt% of Li to the lithium-rich material obtained in the step S1 6.5 La 3 Zr 1.5 Ta 0.5 O 12 And adding 5000ppm of polypropylene pore-repairing agent into the solid protective material according to the mass of the added solid protective material, and uniformly mixing to obtain the lithium-rich material mixed with the protective layer material. Wherein the particle size of the polypropylene pore-repairing agent is 29nm, and the molecular weight is 8 ten thousand Da. S3: mixing the lithium-rich material mixed with the protective layer material obtained in the NMP and the S2, super P and PVDF according to the mass ratio of 100:95:2:3, wherein the mixing mode is ball milling, the ball milling time is 60min, the rotating speed is set to be 30Hz, the lithium-rich positive plate is prepared through homogenating, coating, drying and cutting operations, the lithium-rich positive plate is baked in a vacuum oven at 110 ℃, and the baking treatment time is 20h, so that trace water in the lithium-rich positive plate is removed.
Through test, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 430nm.
Example 5
S1: to lithium-containing metal compound Li 5 FeO 4 And a positive electrode active material LiFePO 4 And uniformly mixing according to the mass ratio of 5:95 to obtain the lithium-rich material.
S2: adding Li accounting for 15 weight percent of the lithium-rich material into the lithium-rich material obtained in the step S1 6.5 La 3 Zr 1.5 Ta 0.5 O 12 And adding 8000ppm of polydimethylsiloxane pore-repairing agent into the solid protective material according to the mass of the added solid protective material, and uniformly mixing to obtain the lithium-rich material mixed with the protective layer material. Wherein the molecular weight of the polydimethylsiloxane pore-repairing agent is 74.15Da, and the evaporation temperature is 155 ℃.
S3: mixing the lithium-rich material mixed with the protective layer material obtained in the NMP and the S2, super P and PVDF according to the mass ratio of 100:95:2:3, wherein the mixing mode is ball milling, the ball milling time is 60min, the rotating speed is set to be 30Hz, the lithium-rich positive plate is prepared through homogenating, coating, drying and cutting operations, the lithium-rich positive plate is baked in a vacuum oven at 120 ℃, and the baking treatment time is 22h, so that trace water in the lithium-rich positive plate is removed.
Through testing, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 526nm.
Example 6
The present example provides a lithium-rich positive electrode sheet containing a protective layer, and the preparation scheme in the lithium-rich positive electrode sheet is the same as that in example 3, except that the pore-repairing agent is 4-trifluoromethylaniline, the molecular weight of the pore-repairing agent is 161.14Da, and the evaporation temperature is 190 ℃.
Through test, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 420nm.
Example 7
The present embodiment provides a lithium-rich positive electrode sheet containing a protective layer, and the preparation scheme in the lithium-rich positive electrode sheet is the same as that of embodiment 1, except that the polyethylene pore-repairing agent adopted in this embodiment has a particle size of 1 μm.
Through testing, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 102nm.
Example 8
The present embodiment provides a lithium-rich positive electrode sheet containing a protective layer, and the preparation scheme in the lithium-rich positive electrode sheet is the same as that of embodiment 1, except that the polyethylene pore-repairing agent adopted in this embodiment has a particle size of 2 μm.
Through tests, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 123nm.
Example 9
The present example provides a lithium-rich positive electrode sheet containing a protective layer, and the preparation scheme in the lithium-rich positive electrode sheet is the same as that of example 1, except that the polyethylene pore-repairing agent adopted in this example has a particle size of 3 μm.
Through testing, the surface of the lithium-rich positive plate is compounded with a protective layer, and the thickness of the protective layer is 136nm.
Comparative example 1
The present comparative example provides a lithium-rich positive electrode sheet compared with the lithium-rich positive electrode sheet prepared in example 1 or any one of examples 3 to 9, except that the surface of the lithium-rich positive electrode sheet of the present comparative example does not contain a protective layer.
S1: lithium supplementing agent Li 5 FeO 4 And a positive electrode material LiFePO 4 And uniformly mixing according to the mass ratio of 5:95 to obtain the anode matrix.
S2: mixing the positive electrode matrix obtained in the NMP and the S1, super P and PVDF according to the mass ratio of 100:95:2:3, wherein the mixing mode is ball milling, the ball milling time is 60min, the rotating speed is set to be 30Hz, the lithium-rich positive electrode plate is prepared through homogenate, coating, drying and cutting operations, the lithium-rich positive electrode plate is baked in a vacuum oven at 120 ℃, and the baking treatment time is 20h, so that trace water in the lithium-rich positive electrode plate is removed.
Comparative example 2
The comparative example provides a lithium-rich positive electrode sheet to be compared with the lithium-rich positive electrode sheet prepared in example 2, except that the surface of the lithium-rich positive electrode sheet of the comparative example does not contain a protective layer.
S1: lithium supplementing agent Li 2 NiO 2 And a positive electrode material LiFePO 4 And uniformly mixing according to the mass ratio of 5:95 to obtain the anode matrix.
S2: mixing the positive electrode matrix obtained in the NMP and the S1, super P and PVDF according to the mass ratio of 100:95:2:3, wherein the mixing mode is ball milling, the ball milling time is 60min, the rotating speed is set to be 30Hz, the lithium-rich positive electrode plate is prepared through homogenate, coating, drying and cutting operations, the lithium-rich positive electrode plate is baked in a vacuum oven at 120 ℃, and the baking treatment time is 22h, so that trace water in the lithium-rich positive electrode plate is removed.
Comparative example 3
This comparative example provides a lithium-rich positive electrode sheet, the preparation method and example 5 differ in that the Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 Solid protective materialThe weight percentage of the polydimethylsiloxane pore-repairing agent is 0.01 percent, and the weight percentage of the polydimethylsiloxane pore-repairing agent is 80ppm.
Comparative example 4
This comparative example provides a lithium-rich positive electrode sheet, the preparation method and example 5 differ in that the Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 The solid protection material accounts for 16 weight percent of the lithium-rich material, and the polydimethylsiloxane pore-repairing agent accounts for 9000ppm of the solid protection material.
Examples 10 to 18
The lithium-rich positive electrode sheets obtained in examples 1 to 9 were assembled into lithium ion batteries of examples 10 to 18, respectively, and the lithium ion batteries were assembled according to the following methods and components:
and (3) a positive electrode: the lithium-rich positive electrode sheets obtained in examples 1 to 9 were used as the positive electrode sheets of the lithium ion batteries of examples 10 to 18, respectively;
and (3) a negative electrode: lithium metal sheet with a diameter of 16 mm;
electrolyte solution: liPF of 1mol/L 6 The solution comprises Ethylene Carbonate (EC) and diethyl carbonate (DEC) according to the volume ratio of 1:1;
a diaphragm: a polypropylene microporous separator;
the lithium ion battery assembling method comprises the following steps: and assembling the lithium ion battery in an inert atmosphere glove box according to the assembling sequence of the lithium metal sheet, the diaphragm, the electrolyte and the positive electrode sheet.
Comparative examples 5 to 8
The lithium-rich positive electrode sheets obtained in comparative examples 1 to 4 were assembled into lithium ion batteries of comparative examples 5 to 8, respectively, and each lithium ion battery was assembled according to the following method and composition:
and (3) a positive electrode: the lithium-rich positive plates obtained in comparative examples 1 to 4 were used as the positive plates of the lithium ion batteries of comparative examples 5 to 8, respectively;
and (3) a negative electrode: lithium metal sheet with a diameter of 16 mm;
electrolyte solution: liPF of 1mol/L 6 The solution comprises Ethylene Carbonate (EC) and diethyl carbonate (DEC) according to the volume ratio of 1:1;
a diaphragm: a polypropylene microporous separator;
the lithium ion battery assembling method comprises the following steps: and assembling the lithium ion battery in an inert atmosphere glove box according to the assembling sequence of the lithium metal sheet, the diaphragm, the electrolyte and the positive electrode sheet.
Example 19
Electrochemical performance tests were performed on the lithium ion batteries prepared in examples 10 to 18 and comparative examples 5 to 8.
The test conditions were: the button cell was charged to 4.3V at a constant current and constant voltage of 0.055C, the off current was 0.01C, left for 10min, discharged to 2.5V at 0.055C, then charged to 3.65V at a constant current and constant voltage of 1C, left for 10min, discharged to 2.5V at a 1C magnification, and circulated for 200 cycles.
The electrochemical properties of the lithium ion batteries prepared in examples 10 to 18 and comparative examples 5 to 8 were measured and are shown in table 1.
TABLE 1
As can be seen from Table 1, the lithium ion batteries prepared in examples 10 to 18 have higher specific capacity in initial charge and discharge and higher capacity retention rate after 200 cycles of 1C than those of the lithium ion batteries prepared in comparative examples 5 to 6, because the protective layer of the pore-repairing agent contained in the positive electrode sheet of the lithium ion batteries prepared in examples 10 to 18 can effectively isolate carbon dioxide and water vapor in the air, the stability of the whole electrode sheet is improved, and the protective layer can also protect the surface of the positive electrode side from metal dissolution during the charge and discharge of the battery, so that the intercalation and deintercalation of lithium ions in the positive and negative electrode materials are not affected, and meanwhile, the particle size of the pore-repairing agent can affect the performance of the battery as can be seen from examples 10, 16, 17 and 18, so that the particle size of the solid pore-repairing agent needs to be kept within a certain range, and the electrochemical performance of the lithium battery is not affected. In comparative examples 7 and 8, since the solid protective material content of the protective layer was not within the values defined in the present invention, the electrochemical properties thereof were significantly lower than those in the other examples.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (11)
1. The lithium-rich positive electrode plate is characterized by comprising a current collector, a lithium-rich material layer formed on the current collector and a protective layer formed on the lithium-rich material layer;
the protective layer comprises a solid protective material and a pore repairing agent.
2. The lithium-rich positive electrode tab of claim 1, wherein the pore-modifying agent fills at least one of the pores formed between the solid protective materials or is sealed at the openings of the pores.
3. The lithium-rich positive electrode sheet according to claim 1, wherein at least one of the solid protective material and the pore-repairing agent has hydrophobicity;
the pore-repairing agent is at least one of a liquid pore-repairing agent or a solid pore-repairing agent.
4. The lithium-rich positive electrode sheet according to claim 3, wherein the molecular weight of the liquid pore-repairing agent is 70Da to 20000Da; the evaporation temperature of the liquid pore-repairing agent is 90-300 ℃;
the particle size of the solid pore-repairing agent is 0.01 nm-3 mu m; the molecular weight of the solid pore-repairing agent is 40000 Da-500000 Da.
5. The lithium-rich positive electrode sheet according to claim 4, wherein the solid protective material is selected from one or more of perovskite type solid protective material, NASICON type solid protective material, garnet type solid protective material, or conductive metal oxide type solid protective material;
the pore-repairing agent is selected from one or more of polyolefin compounds, fluorine-containing amine compounds, ester compounds, nitrile compounds, perfluoroalkyl methacrylic acid polymers, polyorganosiloxane compounds or organosilane compounds.
6. The lithium-rich positive electrode sheet according to claim 1, wherein the mass content of the pore-repairing agent in the protective layer is 90ppm to 8000ppm.
7. The lithium-rich positive electrode sheet according to claim 1, wherein the thickness of the protective layer is 1nm to 20 μm.
8. The lithium-rich positive electrode sheet according to claim 1, wherein the protective layer accounts for 0.1-15 wt% of the lithium-rich material layer.
9. The lithium-rich positive electrode sheet of claim 1, wherein the layer of lithium-rich material comprises a positive electrode active material and a lithium-containing metal compound.
10. A method of preparing the lithium-rich positive electrode sheet of claim 1, comprising:
coating the lithium-rich material layer on the current collector, mixing the solid protection material and the pore-repairing agent, and coating the mixture on the lithium-rich material layer to prepare a lithium-rich positive plate;
or alternatively, the process may be performed,
coating the lithium-rich material layer on the current collector, coating the solid protection material on the lithium-rich material layer, and then coating a pore-repairing agent to prepare a lithium-rich positive plate;
or alternatively, the process may be performed,
coating the lithium-rich material layer on the current collector, coating the pore-repairing agent on the lithium-rich material layer, and then coating a solid protective material to prepare a lithium-rich positive electrode plate;
or alternatively, the process may be performed,
and mixing the lithium-rich material layer, the solid protective material and the pore-repairing agent, and coating the mixture on the current collector to prepare the lithium-rich positive electrode plate.
11. A lithium ion battery comprising the lithium-rich positive electrode sheet according to any one of claims 1 to 9 or the lithium-rich positive electrode sheet obtained by the production method according to claim 10.
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