CN116598443A - Positive electrode lithium supplementing material, preparation method and application thereof - Google Patents
Positive electrode lithium supplementing material, preparation method and application thereof Download PDFInfo
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- CN116598443A CN116598443A CN202310334657.0A CN202310334657A CN116598443A CN 116598443 A CN116598443 A CN 116598443A CN 202310334657 A CN202310334657 A CN 202310334657A CN 116598443 A CN116598443 A CN 116598443A
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- Prior art keywords
- lithium
- positive electrode
- particles
- supplementing
- rich material
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- 239000000463 material Substances 0.000 title claims abstract description 366
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 342
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 340
- 230000001502 supplementing effect Effects 0.000 title claims abstract description 107
- 238000002360 preparation method Methods 0.000 title claims abstract description 34
- 239000002245 particle Substances 0.000 claims abstract description 283
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 175
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 164
- 238000000034 method Methods 0.000 claims abstract description 42
- 230000008569 process Effects 0.000 claims abstract description 33
- 239000000835 fiber Substances 0.000 claims description 108
- 239000002243 precursor Substances 0.000 claims description 70
- 238000002156 mixing Methods 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 18
- 238000005245 sintering Methods 0.000 claims description 13
- 239000011148 porous material Substances 0.000 claims description 10
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 9
- 239000004917 carbon fiber Substances 0.000 claims description 9
- 239000002041 carbon nanotube Substances 0.000 claims description 8
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 8
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 7
- 239000012298 atmosphere Substances 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 4
- 239000011363 dried mixture Substances 0.000 claims description 3
- 230000001681 protective effect Effects 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 25
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 25
- 230000002427 irreversible effect Effects 0.000 abstract description 7
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- GLNWILHOFOBOFD-UHFFFAOYSA-N lithium sulfide Chemical compound [Li+].[Li+].[S-2] GLNWILHOFOBOFD-UHFFFAOYSA-N 0.000 description 31
- 239000000126 substance Substances 0.000 description 14
- 238000007600 charging Methods 0.000 description 12
- 239000011159 matrix material Substances 0.000 description 12
- HSZCZNFXUDYRKD-UHFFFAOYSA-M lithium iodide Chemical compound [Li+].[I-] HSZCZNFXUDYRKD-UHFFFAOYSA-M 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 239000010410 layer Substances 0.000 description 9
- 238000006138 lithiation reaction Methods 0.000 description 9
- 239000002105 nanoparticle Substances 0.000 description 8
- 238000012545 processing Methods 0.000 description 8
- 238000006479 redox reaction Methods 0.000 description 8
- 229910018091 Li 2 S Inorganic materials 0.000 description 7
- 230000002829 reductive effect Effects 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000006258 conductive agent Substances 0.000 description 6
- 230000000670 limiting effect Effects 0.000 description 6
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 description 6
- 229910003002 lithium salt Inorganic materials 0.000 description 6
- 159000000002 lithium salts Chemical class 0.000 description 6
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 description 6
- 238000003860 storage Methods 0.000 description 6
- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 description 6
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- 239000002131 composite material Substances 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 230000001965 increasing effect Effects 0.000 description 4
- 239000007774 positive electrode material Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 238000006722 reduction reaction Methods 0.000 description 4
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- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
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- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 2
- 239000012300 argon atmosphere Substances 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
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- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
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- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 2
- 229910001386 lithium phosphate Inorganic materials 0.000 description 2
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- 238000003756 stirring Methods 0.000 description 2
- 230000008093 supporting effect Effects 0.000 description 2
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 2
- OADJRHDTYUXHAR-UHFFFAOYSA-N 1,3-dioxolan-2-one;ethyl methyl carbonate Chemical compound O=C1OCCO1.CCOC(=O)OC OADJRHDTYUXHAR-UHFFFAOYSA-N 0.000 description 1
- 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
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- 125000003184 C60 fullerene group Chemical group 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- PTHCMJGKKRQCBF-UHFFFAOYSA-N Cellulose, microcrystalline Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC)C(CO)O1 PTHCMJGKKRQCBF-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
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- 239000002033 PVDF binder Substances 0.000 description 1
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- 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
- 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 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
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- 230000015572 biosynthetic process Effects 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical group [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 238000003490 calendering Methods 0.000 description 1
- 239000011203 carbon fibre reinforced carbon Substances 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
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- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
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- 229910021389 graphene Inorganic materials 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 description 1
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 description 1
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 description 1
- 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
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 150000002642 lithium compounds Chemical class 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
- JXGGISJJMPYXGJ-UHFFFAOYSA-N lithium;oxido(oxo)iron Chemical compound [Li+].[O-][Fe]=O JXGGISJJMPYXGJ-UHFFFAOYSA-N 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
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- 239000012982 microporous membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229920000767 polyaniline Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920000128 polypyrrole Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- 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)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application discloses a positive electrode lithium supplementing material, and a preparation method and application thereof. The positive electrode lithium supplementing material comprises carbon particles and lithium-rich material particles; wherein at least a portion of the lithium-rich material particles are dispersed into the carbon particles. The positive electrode lithium supplementing material plays a role in synergy between the carbon particles and at least the lithium-rich material particles dispersed therein, so that the positive electrode lithium supplementing material provides more irreversible lithium ions in the first cycle process, the capacity utilization rate of the lithium-rich material particles is improved, and the lithium supplementing effect of the lithium-rich material particles is improved. In addition, the preparation method of the positive electrode lithium supplementing material can ensure that the structure and the electrochemical performance of the prepared positive electrode lithium supplementing material are stable, the efficiency is high, and the production cost is saved.
Description
Technical Field
The application belongs to the field of lithium batteries, and particularly relates to a positive electrode lithium supplementing material, and a preparation method and application thereof.
Background
The petroleum energy crisis problem in the 60 th and 70 th centuries forces people to find new alternative new energy sources, and the awareness of environmental protection and energy crisis is increased. The lithium ion battery has the advantages of higher working voltage and energy density, relatively smaller self-discharge level, no memory effect, no pollution of heavy metal elements such as lead, cadmium and the like, ultra-long cycle life and the like, and is considered as one of the energy storage and power battery technologies with the best comprehensive performance at present. Lithium ion batteries are widely used in many fields such as electric vehicles, electric tools, mobile electronic consumer goods, energy storage, and the like.
However, at the time of the initial charging process, lithium ions are stored by the positive electrode to the negative electrode, accompanied by formation of a Solid Electrolyte (SEI) on the surface of the negative electrode. This process irreversibly consumes a portion of the active lithium and reduces the capacity and energy density of the battery. Pre-lithiation can introduce additional active lithium into the battery system and is very promising in compensating for initial lithium loss and increasing the energy density of lithium ion batteries.
The lithium-rich material is rich in lithium ions, and can be subjected to lithium removal in the primary charging process to provide lithium ions. For example, lithium sulfide has high theoretical capacity, potential barrier and cut-off discharge potential, and has excellent lithium removing performance. If lithium sulfide has 1166mAh/g of high theoretical capacity, the potential barrier at the initial charge is as high as 3.5V, which is lower than the cut-off charge potential of many existing cathode materials, so that the complete delithiation of lithium sulfide can be ensured. In addition, lithium sulfide also has a higher off-discharge potential than existing cathode materials to avoid electrochemical lithiation of sulfur. Thus, in theory, all active lithium in lithium-rich materials such as lithium sulfide can be irreversibly extracted during the first cycle and used to compensate for the loss of active lithium consumed to form the SEI.
Although lithium-rich materials such as lithium sulfide have the above characteristics, two challenges must be overcome if one wants to fully exploit the high prelithiation capacity of lithium-rich materials, particularly lithium sulfide: (1) The water vapor is easy to absorb in the air to hydrolyze, and the highly toxic hydrogen sulfide gas is emitted, namely, the lithium-rich material such as lithium sulfide has high chemical reactivity with the moisture in the ambient atmosphere; the chemical stability characteristics of this intersection make it difficult for lithium-rich materials to withstand multiple processing steps in battery electrode fabrication, such as exposure to air, slurry mixing and baking, and electrode calendaring under ambient/dry air conditions; (2) Existing commercial lithium-rich materials, such as lithium sulfides in particular, are typically 10 to 30 μm in size and, due to insulating properties, the internal volume of most lithium-rich materials such as lithium sulfides impedes sulfur conversion, resulting in lithium-rich materials exhibiting higher barriers and lower capacity utilization.
These two challenges make lithium-rich materials prohibitive for use in batteries. Therefore, how to improve the chemical stability and reduce the particle size of lithium-rich materials has been a technical problem that the art has attempted to solve.
Disclosure of Invention
The application aims to overcome the defects in the prior art and provide a positive electrode lithium supplementing material and a preparation method thereof, so as to solve the technical problems of low chemical stability and large particle size of a lithium-rich material.
The application further aims to provide a positive plate and a secondary battery containing the positive plate, so as to solve the technical problem of low energy density of the conventional secondary battery containing the lithium-rich material.
In order to achieve the above object, according to a first aspect of the present application, a positive electrode lithium supplementing material is provided. The positive electrode lithium supplementing material comprises lithium-rich material particles and carbon particles; wherein at least a portion of the lithium-rich material particles are dispersed in the carbon particles.
The carbon particles contained in the positive electrode lithium supplementing material play a role of a carbon matrix, so that the lithium-rich material particles are loaded; the lithium-rich material particles are dispersed in the carbon particles, and the carbon particles can protect the lithium-rich material particles and prevent the lithium-rich material particles from directly contacting with the environment, so that the chemical stability of the lithium-rich material particles contained in the positive electrode lithium-supplementing material in applications such as storage and processing is obviously improved. The lithium-rich material particles contained in the positive electrode lithium-supplementing material are rich in lithium and have high lithium removal effect, so that the positive electrode lithium-supplementing material is endowed with excellent lithium supplementing effect, all lithium ions can be released as once as possible in the first-round charging process, and the first effect and the overall electrochemical performance of the battery are improved. Meanwhile, as the lithium-rich material particles are at least partially dispersed in the carbon particles, the particle size of the lithium-rich material particles is effectively inhibited, the particle size of the lithium-rich material particles is effectively reduced, and the dispersibility of the lithium-rich material particles in the carbon particles is improved, so that the pre-lithiation capacity of the lithium-rich material particles is remarkably improved. In addition, the carbon particles also effectively play a good role in electric conduction, so that a synergistic effect is achieved between the carbon particles and the lithium-rich material particles, the positive electrode lithium-supplementing material provided by the application provides more irreversible lithium ions in the first cycle process, the capacity utilization rate of the lithium-rich material particles is improved, and the lithium-supplementing effect of the lithium-rich material particles is improved.
In a second aspect of the present application, a method for preparing the positive electrode lithium-supplementing material of the present application is provided. The preparation method of the positive electrode lithium supplementing material comprises the following steps:
mixing the lithium-rich material and/or the lithium-rich material precursor with a carbon source to prepare a mixture;
and sintering the mixture in a protective atmosphere to generate the positive electrode lithium supplementing material.
According to the preparation method of the positive electrode lithium-supplementing material, the lithium-rich material particles can be effectively dispersed in the carbon particles in-situ, so that the particle size growth of the generated lithium-rich material particles can be restrained, the particle size of the lithium-rich material particles is obviously reduced, the lithium-rich material particles can be uniformly dispersed in the carbon particles, the internal resistance of the prepared positive electrode lithium-supplementing material is reduced on the basis of ensuring the chemical stability of the lithium-rich material particles in the application of storage, processing and the like, the pre-lithiation capacity of the lithium-rich material particles is fully exerted, the capacity utilization rate of the lithium-rich material particles is improved, more irreversible lithium ions are provided by the positive electrode lithium-supplementing material in the first cycle process, and the lithium supplementing effect is improved. In addition, the preparation method of the positive electrode lithium supplementing material can ensure that the structure and the electrochemical performance of the prepared positive electrode lithium supplementing material are stable, the efficiency is high, and the production cost is saved.
In a third aspect of the present application, a positive electrode sheet is provided. The positive plate comprises a positive current collector and a positive active layer combined with the positive current collector, wherein the positive active layer contains the positive lithium supplementing material or the positive lithium supplementing material prepared by the preparation method of the positive lithium supplementing material.
The positive electrode plate contains the positive electrode lithium supplementing material, so that the positive electrode lithium supplementing material can provide more irreversible lithium ions in the first circulation process, thereby having high energy density and low internal resistance of the positive electrode plate.
In a fourth aspect of the present application, a secondary battery is provided. The application comprises a positive plate and a negative plate, wherein the positive plate is the positive plate of the application.
The secondary battery of the application has high initial efficiency and energy density, stable cycle performance and high multiplying power because of the positive plate of the application.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a positive electrode lithium-supplementing material according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a positive electrode lithium supplementing material containing conductive fibers according to an embodiment of the present application;
fig. 3 is a flow chart of a preparation method of a positive electrode lithium supplementing material according to an embodiment of the application.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
In the present application, the term "and/or" describes an association relationship of an association object, which means that three relationships may exist, for example, a and/or B may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.
In the present application, "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
It should be understood that, in various embodiments of the present application, the sequence number of each process described above does not mean that the execution sequence of some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The weights of the relevant components mentioned in the description of the embodiments of the present application may refer not only to the specific contents of the components, but also to the proportional relationship between the weights of the components, so long as the contents of the relevant components in the description of the embodiments of the present application are scaled up or down within the scope of the disclosure of the embodiments of the present application. Specifically, the mass described in the specification of the embodiment of the application can be mass units known in the chemical industry field such as mu g, mg, g, kg.
The terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated for distinguishing between objects such as substances from each other. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the application. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.
In a first aspect, an embodiment of the present application provides a positive electrode lithium supplementing material. In some embodiments of the present application, the structure of the positive electrode lithium-supplementing material according to the embodiment of the present application is shown in fig. 1, and the positive electrode lithium-supplementing material includes carbon particles 1 and lithium-rich material particles 2. Wherein at least part of the lithium rich material particles 2 are dispersed in the carbon particles 1.
The number of the lithium-rich material particles 2 contained in the positive electrode lithium-supplementing material according to the embodiment of the application is not one but plural, for example, two or more. The carbon particles 1 may be primary particles or secondary particles formed by agglomeration of the primary particles. At this time, at least a part of the lithium-rich material particles 2 are dispersed in the carbon particles 1 means that at least a part of the lithium-rich material particles 2 among all the number of lithium-rich material particles 2 are dispersed inside primary particles or secondary particles of the carbon particles 1, and at this time, the lithium-rich material particles 2 dispersed inside the carbon particles 1 are isolated from the outside. The remaining amount of lithium-rich material particles 2 may be bound to the surface of the carbon particles 1. Based on the chemical stability characteristics of the lithium-rich material particles 2 themselves in contact with the environment, it is desirable that more or all of the lithium-rich material particles 2 be dispersed within the carbon particles 1, rather than meaning a mixture of particles of the lithium-rich material particles 2 and the carbon particles 1. Since the lithium-rich material particles 2 are dispersed in the carbon particles 1, the carbon particles 1 constitute a carbon matrix supporting the lithium-rich material particles 2.
Based on the structure of the positive electrode lithium supplementing material, the carbon particles 1 at least can play a role in protecting the lithium-rich material particles 2 dispersed in the particles, and the lithium-rich material particles 2 dispersed in the carbon particles 1 can be isolated from the environment, so that the chemical stability of the lithium-rich material particles 2 in applications including storage, processing and the like is remarkably improved. The lithium-rich material particles 2 are rich in lithium and have high lithium removal effect, so that the positive electrode lithium-supplementing material is endowed with excellent lithium supplementing effect, all lithium ions can be released as once as possible in the first-cycle charging process, and the first effect and the overall electrochemical performance of the battery are improved. And the lithium-rich material particles 2 are dispersed into the carbon particles 1, so that the particle size of the lithium-rich material particles 2 is effectively reduced, and the uniformity of the distribution of the lithium-rich material particles 2 in the carbon particles 1 is improved, thereby obviously improving the pre-lithiation capacity of the lithium-rich material particles 2. The carbon particles 1 have good conductivity, and the characteristic of small particle size of the lithium-rich material particles 2 dispersed in the carbon particles 1 is combined, so that the migration performance of lithium contained in the lithium-rich material particles 2 is remarkably improved, the capacity utilization rate of the lithium-rich material particles 2 is improved, and the lithium supplementing effect of the positive electrode lithium supplementing material is improved. In addition, since the carbon particles 1 have excellent conductivity, the positive electrode lithium-supplementing material of the embodiment of the present application may also be able to function as a conductive agent after the lithium supplementation is completed.
Therefore, the positive electrode lithium supplementing material provided by the embodiment of the application can play a role in synergy among all the components through interaction among the contained components, so that the positive electrode lithium supplementing material provided by the embodiment of the application can provide more irreversible lithium ions in the first cycle process, the lithium supplementing effect is improved, and the conductive agent can play a role after the lithium supplementing effect is finished.
In some embodiments, as shown in fig. 2, the positive electrode lithium supplementing material according to the embodiment of the present application further includes conductive fibers 3. The at least partially conductive fibers 3 are dispersed in the carbon particles 1.
Wherein at least part of the conductive fibers 3 may understand that the number of conductive fibers 3 is plural, such as two or more. At least a part of the conductive fibers 3 dispersed in the carbon particles 1 means that a part of the conductive fibers 3 of all the conductive fibers are dispersed inside the carbon particles 1, and then the remaining conductive fibers 3 may be bonded to the surfaces of the carbon particles 1. At least part of the conductive fibers 3 may also be understood that for individual conductive fibers 3, at least a part of the individual conductive fibers 3 is dispersed into the carbon particles 1.
This is at least partly understood to be at least a part of the number of the plurality of conductive fibers 3 dispersed in the carbon particles 1, or to be at least a part of the individual conductive fibers 3 dispersed in the carbon particles 1. For the embodiment of the present application, it is desirable that more or all of the conductive fibers 3 be dispersed inside the carbon particles 1.
The conductive fibers 3 are additionally arranged and dispersed in the positive electrode lithium supplementing material, and form a composite conductive component with the carbon particles 1 contained in the positive electrode lithium supplementing material, so that the conductive performance of the positive electrode lithium supplementing material is improved, the reinforcing ribs can be also formed in the carbon particles 1, a good mechanical supporting effect can be achieved on the positive electrode lithium supplementing material, and the mechanical strength and structural stability of the positive electrode lithium supplementing material are improved.
In the embodiment, when the positive electrode lithium supplementing material of the embodiment of the present application contains the conductive fiber 3, the conductive fiber 3 forms a network structure in the carbon particles 1, as shown in fig. 2. The conductive fibers 3 are dispersed in the carbon particles 1 in a network structure, so that the conductive fibers 3 construct a conductive network in the carbon particles 1 and form a composite conductive matrix with the carbon particles 1, thereby being capable of remarkably improving the conductive performance of the positive electrode lithium supplementing material, enhancing the effect of reinforcing ribs and improving the mechanical property of the carbon particle structure. At this time, the lithium-rich material particles 2 contained in the positive electrode lithium-supplementing material according to the embodiment of the present application remain at least partially dispersed in the carbon particles 1.
In the embodiment, when the positive electrode lithium supplementing material according to the embodiment of the present application contains the above-described conductive fibers 3, the lithium-rich material particles 2 are not excluded from being attached to the conductive fibers 3 in addition to being dispersed in the carbon particles 1. Wherein attachment to the conductive fibers 3 is understood to be in contact with the surface of the conductive fibers 3 or at least partially dispersed in the surface layer of the conductive fibers 3. The lithium-rich material particles 2 are attached to the conductive fibers 3, so that the effect of isolating the lithium-rich material particles 2 from the environment can be improved, the chemical stability of the lithium-rich material particles 2 can be improved, the characteristic of small particle size of the lithium-rich material particles 2 can be realized, the conductivity can be improved, and the capacity utilization rate of the lithium-rich material particles 2 can be improved.
In the embodiment, the mass ratio of the conductive fiber 3 to the carbon particle 1 in the positive electrode lithium supplementing material according to the embodiments of the present application may be 1: (1 to 10), further may be 1: (1-9), further may be 1: (5-9). In an exemplary embodiment, the mass ratio of the conductive fiber 3 to the carbon particle 1 may be 1: 1. 1: 2. 1: 3. 1: 4. 1: 5. 1: 6. 1: 7. 1: 8. 1: 9. 1:10, etc., typically but not by way of limitation. By adjusting the mass ratio of the conductive fibers 3 to the carbon particles 1, the network structure formed by the conductive fibers 3 in the carbon particles 1 can be adjusted, the structural stability of the conductive fibers with the carbon particles 1 and the formed composite conductive matrix can be enhanced, and the amount of the lithium-rich material particles 2 loaded by the carbon particles 1 can be adjusted.
In embodiments, the conductive fibers 3 in the above embodiments may be of the following dimensions:
the diameter of the conductive fiber 3 may be a nanometer diameter, for example, 10nm to 100nm, and further 60nm to 100nm, and in an exemplary embodiment, the diameter may be a typical but non-limiting diameter of 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70m, 80nm, 90nm, 100nm, 10nm, etc.
The length of the conductive fiber 3 may be in the order of micrometers, for example, 1 μm to 20 μm, and further 5 μm to 10 μm, and in an example, the diameter may be typical but not limited to 1 μm, 3 μm, 5 μm, 7 μm, 10nm, 12 μm, 15 μm, 18 μm, 20 μm, etc.
The conductive fiber 3 with the above size can form a rich network structure in the carbon particles 1, so that the conductivity of a composite conductive matrix formed by the conductive fiber and the carbon particles 1 is improved, the effect of the conductive fiber 3 on the reinforcing ribs in the carbon particles 1 is improved, and the mechanical property of the anode lithium supplementing material is improved.
In an embodiment, the material of the conductive fiber 3 in each of the above embodiments may include at least one of carbon fiber, carbon nanotube, and silicon carbide fiber. The carbon fibers may be carbon nanofibers, and the carbon nanotubes may be array carbon nanotubes. The one-dimensional structural materials have good mechanical properties and excellent conductivity.
In the structure shown in fig. 2, the lithium-rich material particles 2 are at least bound in the carbon matrix 1, and then bound inside the carbon matrix 1, and also bound on the surface of the carbon matrix 1. Based on the chemical instability of the lithium-rich material particles 2 in contact with water, it is desirable to have the lithium-rich material particles 2 dispersed within the carbon matrix 1, i.e., the carbon contained in the carbon matrix 1 is coated with the lithium-rich material particles 2. Thus, the particle size of the lithium-rich material particles 2 can be obviously smaller than that of the existing lithium-rich material particles, and the particles are uniformly dispersed, so that the pre-lithiation capacity of the lithium-rich material particles can be fully exerted, and the capacity utilization rate of the lithium-rich material particles is improved.
In some embodiments, the mass ratio of the lithium-rich material particles 2 to the carbon particles 1 included in the positive electrode lithium-supplementing material in each of the above embodiments may be 70: (20 to 29), further may be 70: (24-29), further may be 70: (27-29). By controlling the mass ratio of the lithium-rich material particles 2 to the carbon particles 1 in the range, the conductivity and the capacity of the positive electrode lithium-supplementing material can be balanced, the pre-lithiation capacity of the lithium-rich material particles 2 can be improved, and the capacity utilization rate of the lithium-rich material particles 2 can be improved.
In some embodiments, the D50 particle size of the carbon particles 1 contained in the positive electrode lithium-supplementing material of the above-described embodiments of the present application may be controlled to be 5 to 30 μm, and in an exemplary embodiment, the D50 particle size may be a typical but non-limiting particle size of 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, 30 μm, etc. Because the carbon particles 1 contained in the positive electrode lithium-supplementing material of the embodiment of the application form a carbon matrix, the particle size range of the positive electrode lithium-supplementing material of the embodiment of the application can be effectively adjusted by adjusting the particle size of the carbon particles 1, and the carbon particles 1 in the particle size range can improve the relevant electrochemical performance of the positive electrode lithium-supplementing material of the embodiment of the application, such as the compaction density and the like of the positive electrode lithium-supplementing material of the embodiment of the application.
In some embodiments, the carbon particles 1 contained in the positive electrode lithium-supplementing material of the above embodiments of the present application contain a porous structure, and the porous structure can be understood as a porous structure. In the embodiment, the pore diameter of the porous structure is 18 nm-900 nm, and the pore volume is 0.09m 3 ·g -1 ～0.15m 3 ·g -1 Specific surface area 138m 2 ·g -1 ～240m 2 ·g -1 。
At this time, it is not excluded that at least part of the lithium-rich material particles 2 are dispersed in the pores of the porous structure. The carbon particles 1 containing the porous structure have the excellent performances of good conductivity, light weight, high toughness, good adsorptivity, easy processing and the like, and meanwhile, the porous carbon with proper pore diameter further regulates and controls the crystal growth condition of the lithium-rich material particles 2, and particularly inhibits the growth of the lithium-rich material particles 2, so that the lithium-rich material particles 2 have the characteristic of small particle size, such as the nano particle size range described below.
In some embodiments, the lithium-rich material particles 2 included in the positive electrode lithium-supplementing material according to the above embodiments of the present application have at least any of the following characteristics:
(1) The lithium-rich material particles are nano particles; in an embodiment, the D50 particle size of the nanoparticle is 5nm to 300nm, and further may be 5nm to 30nm; in an exemplary embodiment, the D50 particle size may be, but is not limited to, a typical diameter of 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 50nm, 100nm, 120nm, 150nm, 180nm, 200nm, 220nm, 250nm, 280nm, 300nm, etc.
(2) The crystal of the lithium-rich material particles is of an inverse fluorite structure;
(3) The morphology of the lithium-rich material particles is at least one of spherical and spheroidal.
Since the lithium-rich material particles 2 are dispersed in the carbon particles 1 of each of the above embodiments, the particle diameter of the lithium-rich material particles 2 can be controlled in the nanometer range. The crystal structure and the morphology of the lithium-rich material particles 2 are further controlled, the stability of the lithium-rich material particles 2 in applications including storage, processing and the like can be improved, the pre-lithiation capacity of the lithium-rich material particles 2 is further improved, and the capacity utilization rate of the lithium-rich material particles is improved.
In some embodiments, the material of the lithium-rich material particles 2 included in the positive electrode lithium-supplementing material according to the above embodiments of the present application may be at least one of a binary lithium-supplementing material and a ternary lithium-supplementing material. Other lithium-rich materials may of course also be included. In an exemplary embodiment, the binary lithium supplementing material may include at least one of lithium sulfide, lithium phosphide, lithium iodide, and lithium bromide. Wherein the lithium sulfide may include a compound of formula Li x S y Wherein 1.ltoreq.x.ltoreq.2, 1.ltoreq.y.ltoreq.6, so that, in an example, the chemical formula of the lithium sulfide may be Li 2 S、Li 2 S、Li 2 S 2 、Li 2 S 4 、Li 2 S 6 At least one of them. These kinds of lithium sulfides 2 have high capacities.
In an exemplary embodiment, the ternary lithium supplement material may include a lithium rich oxide, such as, but not limited to, lithium ferrite, lithium nickelate, and the like.
The lithium-rich material particles 2 are rich in lithium, and can remove lithium in the primary charging process to provide rich lithium ions.
In a second aspect, the embodiment of the application also provides a preparation method of the positive electrode lithium supplementing material. The preparation method of the positive electrode lithium supplementing material provided by the embodiment of the application has a flow chart shown in a figure 3, and comprises the following steps:
s01: mixing a lithium-rich material or/and a lithium-rich material precursor with a carbon source to prepare a mixture;
s02: and sintering the mixture in a protective atmosphere to generate the positive electrode lithium supplementing material.
In the method for preparing a positive electrode lithium-compensating material according to the embodiment of the present application, the lithium-rich material in step S01 should be understood to form the lithium-rich material particles 2 contained in the positive electrode lithium-compensating material according to the embodiment of the present application, the precursor of the lithium-rich material should be understood to form the precursor of the lithium-rich material particles 2 contained in the positive electrode lithium-compensating material according to the embodiment of the present application, and the carbon source should be understood to be the precursor of the carbon-containing particles 1 contained in the positive electrode lithium-compensating material according to the embodiment of the present application. Therefore, the sintering process in step S02 should be such that the carbon source is carbonized to produce carbon particles 1 and the lithium-rich material precursor is fully reacted to produce lithium-rich material particles 2.
Therefore, with reference to fig. 1 to fig. 2, the preparation method of the positive electrode lithium-supplementing material according to the embodiment of the present application can effectively disperse the grown lithium-rich material particles 2 at least in the generated carbon particles 1, so as to inhibit the particle size growth of the generated lithium-rich material particles 2, thereby making the particle size of the lithium-rich material particles 2 small, and as reaching the nano particle size of the lithium-rich material particles 2 contained in the positive electrode lithium-supplementing material according to the embodiment of the present application, the particles can be uniformly dispersed in the carbon particles 1, so that the chemical stability of the lithium-rich material particles 2 in storage and processing is ensured. Meanwhile, the internal resistance of the prepared positive electrode lithium supplementing material is reduced, so that the pre-lithiation capacity of the lithium-rich material particles 2 is fully exerted, the capacity utilization rate of the lithium-rich material particles 2 is improved, more irreversible lithium ions are provided by the positive electrode lithium supplementing material in the first cycle process, and the lithium supplementing effect is improved. In addition, the preparation method of the positive electrode lithium supplementing material can ensure that the prepared positive electrode lithium supplementing material is stable in structure and electrochemical performance, high in efficiency and low in production cost.
Step S01:
the mixing treatment in step S01 is to uniformly mix the lithium-rich material or the lithium-rich material precursor or the lithium-rich material and the lithium-rich material precursor with the carbon source at the same time, so that the lithium-rich material particles 2 and the carbon particles 1 generated after the sintering treatment in step S02 can have the bonding relationship between the lithium-rich material particles 2 and the carbon particles 1 contained in the positive electrode lithium-supplementing material according to the embodiment of the present application, and meanwhile, the uniformity of dispersing the generated lithium-rich material particles 2 in the carbon particles 1 can be improved.
In an embodiment, the method for mixing the lithium-rich material and/or the lithium-rich material precursor with the carbon source in step S01 includes the following steps:
preparing a mixed solution from a lithium-rich material and/or a lithium-rich material precursor and a carbon source, and drying to obtain a dried mixture.
The lithium-rich material and/or the precursor of the lithium-rich material (namely at least one of the lithium-rich material and the precursor of the lithium-rich material) and the precursor of the carbon source and the like are prepared into a mixed solution, so that the dispersion uniformity of the raw materials can be improved. The solvent of the mixed solution should be a precursor capable of dissolving the lithium-rich material (when the lithium-rich material is used as a raw material, the solvent can also dissolve the lithium-rich material), a carbon source, and have no harm or side effects to the raw materials. As in the examples, the solvent may be selected from, but is not limited to, water.
In an embodiment, the drying treatment of the mixed solution may be a freeze-drying treatment. The mixed solution is freeze-dried, so that the dried mixture forms rich pores. That is, the positive electrode lithium supplementing material generated after the sintering treatment in step S02 has a rich pore structure, and specifically, the carbon particles 1 have a rich pore structure.
In the embodiment, the mass ratio of the lithium-rich material and/or the lithium-rich material precursor and the carbon source should ensure that the mass ratio of the lithium-rich material particles 2 and the carbon particles 1 generated correspondingly in the mixing process of the lithium-rich material and/or the lithium-rich material precursor and the carbon source satisfies the mass ratio of the lithium-rich material particles 2 and the carbon particles 1 contained in the positive electrode lithium-supplementing material according to the above embodiment of the present application, for example, in the embodiment, the mass ratio of the generated lithium-rich material particles 2 and the carbon particles 1 satisfies 70: (20-29). Then, as in the example, the mass ratio of the lithium-rich material precursor to the carbon source may be 10:25 or more, further may be 10:50 to 10:60, and in an exemplary example, may be 10: 51. 10: 52. 10: 53. 10: 54. 10: 55. 10: 56. 10: 57. 10: 58. 10: 59. 10:60, etc., by way of non-limiting example. And the mass ratio of the generated lithium-rich material particles 2 to the carbon particles 1 can be adjusted by adjusting the mass ratio of the lithium-rich material and/or the lithium-rich material precursor to the carbon source.
In an exemplary embodiment, the carbon source may include at least one of a polymer, a resin, and a saccharide. Wherein the polymer may include at least one of polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), and Polyacrylonitrile (PAN). The saccharide may include at least one of glucose, starch, chitosan, etc. The preparation method comprises the steps of selecting a polymer or saccharide with higher molecular weight as a carbon source to form a long-chain packaging layer, controlling the growth of a lithium-rich material by using a suspension liquid in the long-chain packaging layer, specifically, inhibiting heterogeneous nucleation through physical confinement in the process of converting a lithium-rich precursor into the lithium-rich material, and introducing stable lithium-rich material nano particles.
In an exemplary embodiment, the lithium-rich material precursor may include a binary lithium-supplementing material, a ternary lithium-supplementing material precursor as described above, such as at least one of a lithium salt that may contain sulfur and lithium, a lithium salt that contains phosphorus and lithium, a lithium salt that contains iodine and lithium, a lithium salt that contains bromine and lithium, and a lithium salt that contains nitrogen and lithium. The lithium salt may include at least one of lithium sulfate, lithium phosphate, lithium iodide, and lithium bromide. In embodiments, the lithium-rich material particles may include at least one of lithium sulfide, lithium phosphide, lithium iodide, lithium bromide, and the like.
In some embodiments, during the mixing process in step S01, conductive fibers and/or conductive fiber precursors are also added and formed into a mixture with the lithium-rich material and/or lithium-rich material precursors, a carbon source.
The conductive fibers are understood to form the conductive fibers 3 contained in the positive electrode lithium supplementing material according to the embodiment of the present application, and the conductive fiber precursor is understood to be the precursor of the conductive fibers 3 contained in the positive electrode lithium supplementing material according to the embodiment of the present application.
By adding the conductive fibers and/or conductive fiber precursors to the mixture, the conductive fibers and/or conductive fiber precursors and the lithium-rich material and/or lithium-rich material precursors, the carbon source, are formed into a uniform mixture, such as a slurry layer, on the surface of the conductive fibers or conductive fiber precursors during the mixing process in step S01. In this way, the conductive fibers and/or conductive fibers produced from the conductive fiber precursor after the sintering treatment in step S02 can have the conductive fibers 3 contained in the positive electrode lithium supplementing material according to the embodiment of the present application described above.
In addition, the mode of mixing the conductive fibers and/or the conductive fiber precursors with the lithium-rich material precursors and the carbon source is controlled, so that the distribution state of the finally formed conductive fibers 3, the lithium-rich material particles 2 and the carbon particles 1 in the positive electrode lithium-supplementing material can be controlled, and a rich network structure shown in fig. 2 can be formed in the carbon particles 1.
In the embodiment, in the mixing process of the conductive fiber and/or the conductive fiber precursor and the lithium-rich material and/or the lithium-rich material precursor and the carbon source, the mixing ratio of the conductive fiber and/or the conductive fiber precursor and the lithium-rich material and/or the lithium-rich material precursor and the carbon source should ensure that the mass ratio of the conductive fiber 3 to the lithium-rich material particles 2 and the carbon particles 1 correspondingly generated satisfies the mass ratio of the lithium-rich material particles 2 and the carbon particles 1 contained in the positive electrode lithium-supplementing material according to the embodiment of the present application, for example, in the embodiment, the mass ratio of the conductive fiber 3 to the carbon particles 1 generated satisfies 1: (1-10). Then, as in the examples, the mass ratio of the conductive fiber precursor to the lithium-rich material precursor may be controlled to be 10: (10 to 20), further may be 10: (15-20), in an exemplary example, may be 10: 15. 10: 16. 10: 17. 10: 18. 10: 19. 10:20, etc., by way of non-limiting example.
In an exemplary embodiment, the conductive fiber precursor includes at least one of bacterial cellulose, microcrystalline cellulose, polyaniline fiber, polypyrrole fiber, and polythiophene fiber.
In an exemplary embodiment, the conductive fibers include at least one of carbon nanofibers, carbon nanotubes, and silicon carbide fibers. The carbon fibers may be carbon nanofibers, and the carbon nanotubes may be array carbon nanotubes.
By selecting the types of the raw materials such as the conductive fibers and/or the conductive fiber precursors, the lithium-rich materials, and/or the lithium-rich material precursors, the dispersibility of the raw materials can be improved. And the types of conductive fibers and/or conductive fiber precursors, lithium-rich materials, and/or lithium-rich material precursors can be dispersed in a carbon source solution. In another embodiment, a surfactant may be added during the mixing process of the conductor and/or conductor precursor with the lithium-rich material and/or lithium-rich material precursor, the carbon source, and the surfactant may include, but is not limited to, a cationic surfactant. The addition of the surfactant can repel the conductive fibers and/or the conductive fiber precursors from each other, and can effectively improve the dispersion uniformity of the conductive body and/or the conductive body precursors in the mixture, thereby forming a rich conductive network structure in the carbon particles 1.
Step S02:
by the sintering process in step S02, the mixture in step S01 is sintered to produce a sintered product, and the carbon source is carbonized to produce carbon, specifically, carbon particles 1 included in the positive electrode lithium-supplementing material constituting the above-described embodiment of the present application. When the mixture contains the conductive fiber precursor, the conductive fiber precursor is sintered to generate conductive fibers, and the conductive fibers 3 contained in the positive electrode lithium supplementing material in the embodiment of the application are specifically formed. When the mixture contains conductive fibers, the conductive fibers directly form the conductive fibers 3 contained in the positive electrode lithium supplementing material of the embodiment of the application.
In addition, in the mixture, the carbon source can play a role in loading the lithium-rich material precursor, the lithium-rich material and/or the lithium-rich material precursor are dispersed in the carbon source, and when the carbon particles 1 formed by carbonization play an isolating role in the sintering treatment process, the generated lithium-rich material particles 2 are prevented from growing up, so that the particle size of the lithium-rich material particles 2 is effectively reduced, and the lithium-rich material particles 2 can be nano particles.
In an embodiment, the sintering process in step S02 may include a low-temperature pre-sintering process and a high-temperature oxidation-reduction reaction process. The particle size uniformity of the positive electrode lithium supplementing material can be improved by subjecting the mixture to a sectional sintering treatment. It was detected that during the sintering process in step S02, the carbon source is mostly consumed during the oxidation-reduction process of the cracking, e.g. the amount of the finally produced carbon matrix 1 is about 16% of the remaining carbon source, i.e. about 84% of the carbon source is consumed by decomposition.
Wherein the temperature of the pre-carbonization treatment can be 200-300 ℃. By controlling the pre-carbonization temperature within this range, at least a part of the carbon source can be carbonized to generate carbon, and when the conductive fiber precursor is contained, at least a part of the conductive fiber precursor or the like can be generated to generate conductive fibers. In addition, the time of the preliminary carbonization treatment should be sufficient, for example, the time of the preliminary carbonization treatment may be controlled to be 1 to 10 hours at the preliminary carbonization treatment temperature.
The oxidation-reduction reaction in step S02 can ensure that all the carbon source, the precursor of the lithium-rich material, the precursor of the further conductive fiber, and the like react to generate corresponding carbon, lithium-rich material particles and conductive fibers, that is, the carbon particles 1, the lithium-rich material particles 2 or the further conductive fibers 3 contained in the positive electrode lithium-supplementing material respectively form the embodiment of the application. When the lithium-rich material precursor contains lithium sulfate, for example, the lithium sulfate may react during the redox process as follows:
Li 2 SO 4 +2C＝Li 2 S+2CO 2
Li 2 SO 4 +4C＝Li 2 S+4CO
that is, carbon generated from the carbon source acts as a reducing agent during the oxidation-reduction reaction, reacts with lithium sulfate to be oxidized into gas, and is reduced into lithium sulfide, and during this process, carbon is consumed to some extent and forms a porous structure to provide a receiving space of lithium sulfide and limit a growth space of lithium sulfide.
In an embodiment, the temperature of the oxidation-reduction reaction may be 600 to 800 ℃, and may further be 680 to 700 ℃. The oxidation-reduction reaction in the temperature range can ensure that all carbon sources, lithium-rich material precursors or further conductive fiber precursors and the like react to generate corresponding carbon, lithium-rich material particles and conductive fibers, and the microstructure of the generated positive electrode lithium-supplementing material can be regulated on the basis. In addition, the time of the redox reaction should be sufficient, for example, at the redox reaction temperature, the time of the redox reaction may be controlled to 2 to 15 hours.
In a third aspect, the embodiment of the application also provides a positive plate. The positive plate comprises a positive current collector and a positive active layer combined with the positive current collector, wherein the positive active layer contains the positive lithium supplementing material of the embodiment of the application. Because the positive plate of the embodiment of the application contains the positive lithium supplementing material of the embodiment of the application, the positive lithium supplementing material contained in the positive plate plays the role in the charging and discharging process, can be used as a lithium source to be consumed as a sacrificial agent in the first-round charging process for supplementing irreversible lithium ions consumed by forming an SEI film by the negative electrode, thereby maintaining the abundance of lithium ions in a battery system and improving the initial efficiency and the overall electrochemical performance of the battery. And the electrode plate has stable quality and high yield.
In one embodiment, the mass content of the positive electrode lithium supplementing material of the embodiment of the present application contained in the positive electrode active layer may be 3 to 8wt%; preferably 4 to 6wt%. The positive electrode active layer includes a positive electrode active material, a binder and a conductive agent in addition to the positive electrode lithium supplementing material, wherein the binder may be a common electrode binder such as 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 an embodiment of the present application, the conductive agent may be a conventional conductive agent such as one or more including graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotube. The electrode active material may be a positive electrode active material or a negative electrode active material, and in a specific embodiment, the positive electrode active material includes 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 cobalt manganate, and lithium nickel cobalt aluminate.
In an embodiment, the preparation process of the positive electrode sheet may be: and mixing the positive electrode active material, the positive electrode lithium supplementing material, the conductive agent and the binder to obtain electrode slurry, coating the electrode slurry on a positive electrode current collector, and preparing the positive electrode plate through the steps of drying, rolling, die cutting and the like.
In a fourth aspect, an embodiment of the present application also provides a secondary battery. The secondary battery provided by the embodiment of the application comprises necessary components such as a positive plate, a negative plate, a diaphragm, electrolyte and the like, and other necessary or auxiliary components. The positive plate is the positive plate of the embodiment of the application and contains the positive lithium supplementing material of the embodiment of the application.
The secondary battery provided by the embodiment of the application contains the positive electrode lithium supplementing material of the embodiment of the application, and the positive electrode lithium supplementing material based on the embodiment of the application has excellent lithium supplementing performance or further has electronic conductivity, storage and processing performance, so that the secondary battery provided by the embodiment of the application has excellent first coulombic efficiency, battery capacity and cycle performance, long service life and stable electrochemical performance.
The following examples are provided to illustrate the positive electrode lithium supplementing material, the preparation method and the application thereof.
1. Positive electrode lithium supplementing material and particle diameter control method embodiment:
example 1
The embodiment provides a positive electrode lithium supplementing material and a preparation method thereof. The structure of the positive electrode lithium supplementing material is shown in fig. 1, and comprises carbon particles 1 and lithium sulfide (lithium-rich material particles 2) at least partially dispersed in the carbon particles 1.
The preparation method of the positive electrode lithium supplementing material comprises the following steps:
s1, dissolving 10g of lithium sulfate and 58g of chitosan in 1000ml of deionized water, stirring and dissolving to form a uniform mixed solution, and freeze-drying for 12 hours to obtain a precursor;
s2, keeping the temperature of the precursor at 200 ℃ for 1h under the argon atmosphere, keeping the temperature at 250 ℃ for 5h for pretreatment carbonization, and then keeping the temperature at 680 ℃ for 5h for oxidation reduction; cooling, transferring into a glove box, crushing and grinding.
Example 2
The embodiment provides a positive electrode lithium supplementing material and a preparation method thereof. The positive electrode lithium supplementing material comprises conductive fibers, carbon particles and lithium sulfide particles, wherein the lithium sulfide particles and at least most of the conductive fibers are dispersed in the carbon particles, and the conductive fibers form a conductive network structure in the carbon particles. The data such as D50 particle diameters of the carbon particles and lithium sulfide particles, which are the conductive fibers, are shown in table 1 below.
The preparation method of the positive electrode lithium supplementing material comprises the following steps:
s1, dissolving 10g of lithium sulfate and 58g of chitosan in 1000ml of deionized water to completely dissolve to form uniform solution A; slowly pouring 34g of bacterial cellulose aqueous solution (0.6%) treated by the cationic surfactant into the solution A, uniformly stirring by ultrasonic, and freeze-drying for 12 hours to obtain a precursor;
S2, preserving heat at 200 ℃ for 1h under argon atmosphere, heating to 250 ℃ for 5h, pretreating and carbonizing, and heating to 680 ℃ for 5h through high-temperature oxidation and reduction; cooling, transferring into a glove box, crushing and grinding.
Example 3
The embodiment provides a positive electrode lithium supplementing material and a preparation method thereof. The structure of the positive electrode lithium-supplementing material was the same as that of the positive electrode lithium-supplementing material in example 2. The data such as D50 particle diameter of the carbonaceous particles and lithium sulfide particles are shown in Table 1.
The preparation method of the positive electrode lithium supplementing material comprises the following steps:
s1, the same as the step S1 in the embodiment 2;
s2, unlike the step S2 in the example 2, the temperature is increased to 600 ℃ and the oxidation and reduction are carried out for 10 hours.
Example 4
The embodiment provides a positive electrode lithium supplementing material and a preparation method thereof. The structure of the positive electrode lithium-supplementing material was the same as that of the positive electrode lithium-supplementing material in example 2. The data such as D50 particle diameter of the carbonaceous particles and lithium sulfide particles are shown in Table 1.
The preparation method of the positive electrode lithium supplementing material comprises the following steps:
s1, the same as the step S1 in the embodiment 2;
s2, unlike the step S2 in the example 2, the temperature is increased to 800 ℃ and the oxidation and reduction are carried out for 5 hours.
Example 5
The embodiment provides a positive electrode lithium supplementing material and a preparation method thereof. The structure of the positive electrode lithium-supplementing material was the same as that of the positive electrode lithium-supplementing material in example 2. The data such as D50 particle diameter of the carbonaceous particles and lithium sulfide particles are shown in Table 1.
The preparation method of the positive electrode lithium supplementing material comprises the following steps:
s1, different from the step S1 in the embodiment 2; bacterial cellulose treated with an anionic surfactant;
s2. The procedure is the same as in step S2 of example 2.
Example 6
The embodiment provides a positive electrode lithium supplementing material and a preparation method thereof. The structure of the positive electrode lithium-supplementing material was the same as that of the positive electrode lithium-supplementing material in example 2. The data of the D50 particle diameter and the like of the carbon-containing particles and the lithium phosphide particles are shown in the following Table 1.
The preparation method of the positive electrode lithium supplementing material comprises the following steps:
s1, unlike the step S1 in the embodiment 2, 12g of lithium phosphate is adopted as a precursor of a lithium-rich material;
s2. The procedure is the same as in step S2 of example 2.
Example 7
The embodiment provides a positive electrode lithium supplementing material and a preparation method thereof. The structure of the positive electrode lithium-supplementing material was the same as that of the positive electrode lithium-supplementing material in example 2. The data such as D50 particle diameters of the carbon-containing particles and lithium iodide particles are shown in Table 1 below.
The preparation method of the positive electrode lithium supplementing material comprises the following steps:
s1, unlike the step S1 in the embodiment 2, 13g of lithium iodide is adopted as a precursor of a lithium-rich material;
s2. The procedure is the same as in step S2 of example 2.
Comparative example 1
This comparative example provides a lithium sulfide. The lithium sulfide was commercially available existing lithium sulfide having a particle size of 10 to 30 μm, as shown in Table 1 below.
2. Lithium ion battery examples:
the positive electrode lithium-supplementing materials provided in examples 1 to 8 and the positive electrode lithium-supplementing materials provided in comparative examples described above were assembled into a positive electrode and a lithium ion battery, respectively, as follows:
positive electrode: under the same conditions, the following (main material+lithium supplementing material): super P-Li: PVDF, mixing the materials in a mass ratio of 95:2:3, wherein the main material is nano lithium iron phosphate material, the lithium supplementing material is 3% of the main material in mass, uniformly mixing the materials by taking N-methyl pyrrolidone (NMP) as a solvent to prepare slurry, uniformly coating the slurry on the surface of an aluminum foil, rolling the aluminum foil to a certain thickness, and vacuum drying the aluminum foil at 110 ℃ for 12 hours to prepare the positive electrode plate; wherein the lithium supplementing materials are the above examples 1 to 1 respectively8The provided positive electrode lithium supplementing material and the positive electrode lithium supplementing material provided by the comparative example;
A counter electrode: lithium metal sheet;
electrolyte solution: liPF with electrolyte of 1mol/L 6 Ethylene carbonate methyl ethyl carbonate (volume ratio) =1:1 solution;
a diaphragm: a polypropylene microporous membrane;
a battery case: model CR2032 (including negative electrode shell, stainless steel gasket and positive electrode shell)
And (3) assembling a lithium ion battery: the assembly sequence of the cathode shell, the stainless steel gasket, the lithium metal sheet, the diaphragm, the electrolyte, the anode sheet and the anode shell is assembled into a half cell in an inert atmosphere glove box.
3. Lithium ion battery related performance test
Testing the related electrochemical performance of each lithium ion battery assembled in the lithium ion battery embodiment, wherein the testing conditions are as follows:
test conditions: the assembled battery is put on a stand in a constant temperature chamber at 25 ℃ and is subjected to charge and discharge test after being placed for 6 hours. Firstly, charging to 4.5V at a constant current of 0.05C, then charging to a constant voltage until the cut-off current is 0.01C, discharging to 2V at 0.05C, adjusting a charging and discharging voltage window to 2.5-4.2V at the beginning of the second circle, charging and discharging at 0.05C, and circulating to 100 circles under the charging and discharging conditions at the constant voltage charging and cut-off current of 0.01C. The first charge and discharge capacity of the battery was recorded.
The first coulombic efficiency is the ratio of the first discharge capacity to the first charge capacity, and the 100-turn capacity retention rate is the ratio of the 100-turn discharge capacity to the first discharge capacity.
The relevant electrochemical properties of the lithium ion battery are shown in the following table 1:
TABLE 1
Thus, it can be seen from the data results of the examples and comparative examples in table 1: the particle size of the lithium-rich material particles and the addition amount of the carbon particles are closely related to the battery performance, and the micron-sized lithium sulfide in comparative example 1 has no gain on the battery performance, but causes performance degradation, while in the embodiment of the application, the carbon source such as a sugar liquid phase uniformly disperses the precursor, and the high-temperature carbothermal reduction lithium compound inhibits the crystal growth thereof to obtain the nano-sized ideal product. The nano particle size overcomes the influence of large internal resistance caused by large size, greatly reduces the difficulty of lithium ion migration, and fully releases the lithium supplementing capacity; the conductivity of the carbon fiber is several orders of magnitude of that of the porous carbon, and the carbon fiber and carbon particles with proper mass distribution effectively improve the overall conductivity of the lithium supplementing agent, so that the performances of initial charge, multiplying power, capacity retention rate and the like of the battery are affected. The cationic surfactant prevents carbon fibers from agglomerating, enhances the dispersion uniformity of the carbon fibers in the carbon particles and the formed conductive network structure, improves the conductivity of the carbon particles, reduces the particle size of the formed carbon particles, and fully exerts the capacity of the lithium supplementing material.
The foregoing examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (10)
1. The positive electrode lithium supplementing material is characterized in that: comprising lithium-rich material particles and carbon particles; wherein at least a portion of the lithium-rich material particles are dispersed in the carbon particles.
2. The positive electrode lithium supplementing material according to claim 1, wherein: further comprising conductive fibers, at least a portion of the conductive fibers being dispersed in the carbon particles.
3. The positive electrode lithium supplementing material according to claim 2, wherein: the conductive fibers dispersed in the carbon particles form a network structure.
4. The positive electrode lithium-supplementing material according to any one of claims 2 to 3, wherein: the conductive fiber comprises at least one of carbon fiber, carbon nanotube and silicon carbide fiber; and/or
The diameter of the conductive fiber is 10 nm-100 nm; and/or
The length of the conductive fiber is 1-20 mu m; and/or
The mass ratio of the conductive fiber to the carbon particles is 1: (1-10).
5. The positive electrode lithium-supplementing material according to any one of claims 2 to 3, wherein: the lithium-rich material particles comprise at least one of a binary lithium-supplementing material and a ternary lithium-supplementing material; and/or
The mass ratio of the lithium-rich material particles to the carbon particles is 70: (20-29); and/or
The particle diameter D50 of the lithium-rich material particles is 5-300 nm.
6. The positive electrode lithium-supplementing material according to any one of claims 2 to 3, wherein: the carbon particles comprise a multi-pore structure, and at least part of the lithium-rich material particles are dispersed in pores of the multi-pore structure; and/or
The carbon particles have a particle diameter D50 of 5-30 μm.
7. The preparation method of the positive electrode lithium supplementing material is characterized by comprising the following steps of:
mixing the lithium-rich material and/or the lithium-rich material precursor with a carbon source to prepare a mixture;
and sintering the mixture in a protective atmosphere to generate the positive electrode lithium supplementing material.
8. The method of claim 7, wherein the method of mixing the lithium-rich material and/or the lithium-rich material precursor with the carbon source comprises the steps of:
Preparing the lithium-rich material and/or the lithium-rich material precursor and the carbon source into a mixed solution, and drying to obtain a dried mixture;
and/or
And in the mixing treatment process, conductive fibers or conductive fiber precursors are also added, and the conductive fibers and/or conductive fiber precursors, the lithium-rich material and/or the lithium-rich material precursors and a carbon source form the mixture together.
9. A positive electrode sheet comprising a positive electrode current collector and a positive electrode active layer bonded to the positive electrode current collector, characterized in that: the positive electrode active layer contains the positive electrode lithium supplementing material according to any one of claims 1 to 6 or the positive electrode lithium supplementing material prepared by the preparation method according to claim 7 or 8.
10. A secondary battery, includes positive plate and negative plate, its characterized in that: the positive electrode sheet is the positive electrode sheet according to claim 9.
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