CN115088127B - Electrochemical device - Google Patents
Electrochemical device Download PDFInfo
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- CN115088127B CN115088127B CN202080096453.2A CN202080096453A CN115088127B CN 115088127 B CN115088127 B CN 115088127B CN 202080096453 A CN202080096453 A CN 202080096453A CN 115088127 B CN115088127 B CN 115088127B
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- 239000010954 inorganic particle Substances 0.000 claims abstract description 106
- 239000011148 porous material Substances 0.000 claims abstract description 89
- 239000002245 particle Substances 0.000 claims abstract description 88
- 229920005594 polymer fiber Polymers 0.000 claims abstract description 51
- 239000002033 PVDF binder Substances 0.000 claims description 18
- -1 polypropylene carbonate Polymers 0.000 claims description 18
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 18
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 12
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 12
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 10
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 10
- 229920000379 polypropylene carbonate Polymers 0.000 claims description 10
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 8
- 239000000919 ceramic Substances 0.000 claims description 8
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 6
- 239000004952 Polyamide Substances 0.000 claims description 6
- 239000002202 Polyethylene glycol Substances 0.000 claims description 6
- 239000004642 Polyimide Substances 0.000 claims description 6
- 239000011521 glass Substances 0.000 claims description 6
- 229910052744 lithium Inorganic materials 0.000 claims description 6
- 229920005569 poly(vinylidene fluoride-co-hexafluoropropylene) Polymers 0.000 claims description 6
- 229920002647 polyamide Polymers 0.000 claims description 6
- 229920001223 polyethylene glycol Polymers 0.000 claims description 6
- 229920000139 polyethylene terephthalate Polymers 0.000 claims description 6
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 6
- 229920001721 polyimide Polymers 0.000 claims description 6
- 239000004721 Polyphenylene oxide Substances 0.000 claims description 5
- 229920006380 polyphenylene oxide Polymers 0.000 claims description 5
- 229910008550 Li2O—Al2O3—SiO2—P2O5—TiO2—GeO2 Inorganic materials 0.000 claims description 4
- 229910010093 LiAlO Inorganic materials 0.000 claims description 4
- PPVYRCKAOVCGRJ-UHFFFAOYSA-K P(=S)([O-])([O-])[O-].[Ge+2].[Li+] Chemical compound P(=S)([O-])([O-])[O-].[Ge+2].[Li+] PPVYRCKAOVCGRJ-UHFFFAOYSA-K 0.000 claims description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 4
- 229910006404 SnO 2 Inorganic materials 0.000 claims description 4
- 229910002367 SrTiO Inorganic materials 0.000 claims description 4
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 4
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 4
- 229910001593 boehmite Inorganic materials 0.000 claims description 4
- 239000002223 garnet Substances 0.000 claims description 4
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 4
- 229910000659 lithium lanthanum titanates (LLT) Inorganic materials 0.000 claims description 4
- 229910001386 lithium phosphate Inorganic materials 0.000 claims description 4
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 4
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 4
- 239000000347 magnesium hydroxide Substances 0.000 claims description 4
- 229920000131 polyvinylidene Polymers 0.000 claims description 4
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 claims description 4
- IDBFBDSKYCUNPW-UHFFFAOYSA-N lithium nitride Chemical compound [Li]N([Li])[Li] IDBFBDSKYCUNPW-UHFFFAOYSA-N 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 32
- 229910001416 lithium ion Inorganic materials 0.000 description 32
- 238000011049 filling Methods 0.000 description 25
- 239000000835 fiber Substances 0.000 description 19
- 238000000034 method Methods 0.000 description 18
- 239000011159 matrix material Substances 0.000 description 15
- 238000002360 preparation method Methods 0.000 description 14
- 238000009987 spinning Methods 0.000 description 13
- 239000002002 slurry Substances 0.000 description 12
- 239000007774 positive electrode material Substances 0.000 description 11
- 239000002904 solvent Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 229910003002 lithium salt Inorganic materials 0.000 description 6
- 159000000002 lithium salts Chemical class 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 5
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 238000001523 electrospinning Methods 0.000 description 5
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 239000007773 negative electrode material Substances 0.000 description 5
- 229920000642 polymer Polymers 0.000 description 5
- 229920001955 polyphenylene ether Polymers 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 238000000151 deposition Methods 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- 238000003475 lamination Methods 0.000 description 4
- 230000035515 penetration Effects 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- 229910000838 Al alloy Inorganic materials 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-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
- 230000005540 biological transmission Effects 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000007787 electrohydrodynamic spraying Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- BHZCMUVGYXEBMY-UHFFFAOYSA-N trilithium;azanide Chemical compound [Li+].[Li+].[Li+].[NH2-] BHZCMUVGYXEBMY-UHFFFAOYSA-N 0.000 description 3
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 2
- BJWMSGRKJIOCNR-UHFFFAOYSA-N 4-ethenyl-1,3-dioxolan-2-one Chemical compound C=CC1COC(=O)O1 BJWMSGRKJIOCNR-UHFFFAOYSA-N 0.000 description 2
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 2
- MKGYHFFYERNDHK-UHFFFAOYSA-K P(=O)([O-])([O-])[O-].[Ti+4].[Li+] Chemical compound P(=O)([O-])([O-])[O-].[Ti+4].[Li+] MKGYHFFYERNDHK-UHFFFAOYSA-K 0.000 description 2
- CVJYOKLQNGVTIS-UHFFFAOYSA-K aluminum;lithium;titanium(4+);phosphate Chemical compound [Li+].[Al+3].[Ti+4].[O-]P([O-])([O-])=O CVJYOKLQNGVTIS-UHFFFAOYSA-K 0.000 description 2
- 239000006183 anode active material Substances 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- VUPKGFBOKBGHFZ-UHFFFAOYSA-N dipropyl carbonate Chemical compound CCCOC(=O)OCCC VUPKGFBOKBGHFZ-UHFFFAOYSA-N 0.000 description 2
- 238000004070 electrodeposition Methods 0.000 description 2
- 229910052733 gallium Inorganic materials 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910000664 lithium aluminum titanium phosphates (LATP) Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- KKQAVHGECIBFRQ-UHFFFAOYSA-N methyl propyl carbonate Chemical compound CCCOC(=O)OC KKQAVHGECIBFRQ-UHFFFAOYSA-N 0.000 description 2
- 239000002121 nanofiber Substances 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- DSMUTQTWFHVVGQ-UHFFFAOYSA-N 4,5-difluoro-1,3-dioxolan-2-one Chemical compound FC1OC(=O)OC1F DSMUTQTWFHVVGQ-UHFFFAOYSA-N 0.000 description 1
- AQJSPWIJMNBRJR-UHFFFAOYSA-N 4,5-difluoro-4-methyl-1,3-dioxolan-2-one Chemical compound CC1(F)OC(=O)OC1F AQJSPWIJMNBRJR-UHFFFAOYSA-N 0.000 description 1
- PYKQXOJJRYRIHH-UHFFFAOYSA-N 4-fluoro-4-methyl-1,3-dioxolan-2-one Chemical compound CC1(F)COC(=O)O1 PYKQXOJJRYRIHH-UHFFFAOYSA-N 0.000 description 1
- LECKFEZRJJNBNI-UHFFFAOYSA-N 4-fluoro-5-methyl-1,3-dioxolan-2-one Chemical compound CC1OC(=O)OC1F LECKFEZRJJNBNI-UHFFFAOYSA-N 0.000 description 1
- 229910015015 LiAsF 6 Inorganic materials 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910013684 LiClO 4 Inorganic materials 0.000 description 1
- 229910013528 LiN(SO2 CF3)2 Inorganic materials 0.000 description 1
- 229910012258 LiPO Inorganic materials 0.000 description 1
- 229910020346 SiS 2 Inorganic materials 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-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
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical class [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000010042 air jet spinning Methods 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- LEGITHRSIRNTQV-UHFFFAOYSA-N carbonic acid;3,3,3-trifluoroprop-1-ene Chemical compound OC(O)=O.FC(F)(F)C=C LEGITHRSIRNTQV-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000011161 development Methods 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
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000007590 electrostatic spraying Methods 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- QQUZYDCFSDMNPX-UHFFFAOYSA-N ethene;4-methyl-1,3-dioxolan-2-one Chemical compound C=C.CC1COC(=O)O1 QQUZYDCFSDMNPX-UHFFFAOYSA-N 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000011244 liquid electrolyte Substances 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 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
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- 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)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Secondary Cells (AREA)
- Cell Separators (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
An electrochemical device comprising: a first pole piece, and a first porous layer disposed on a surface of the first pole piece, a second pole piece: wherein the first porous layer comprises first polymer fibers and first inorganic particles, the average pore diameter of pores formed by the first polymer fibers in a region far from the first pole piece is A [ mu ] m, the average pore diameter of pores formed by the first polymer fibers in a region near to the first pole piece is B [ mu ] m, the average particle diameter of the first inorganic particles in a region far from the first pole piece is C [ mu ] m, the average particle diameter of the first inorganic particles in a region near to the first pole piece is D [ mu ] m, and the following relation is satisfied: (a) A > B; (b) C > D. With the electrochemical device, both self-discharge problems and electrical properties are improved.
Description
Technical Field
The present application relates to an electrochemical device and an electronic device including the same, and more particularly, to a lithium ion battery and an electronic device including the same.
Background
The lithium ion battery has the advantages of high energy density, long cycle life, high nominal voltage (more than 3.7V), low self-discharge rate and the like, and has wide application in the consumer electronics field. With the rapid development of electric vehicles and mobile electronic devices in recent years, the requirements of lithium ion batteries on energy density, safety, cycle performance and the like are increasingly high, and the appearance of novel lithium ion batteries with comprehensive improvement of comprehensive performance is expected. Among them, a fibrous porous layer is provided between the positive and negative electrodes of a lithium ion battery to replace a conventional common separator, which is a new technology of great attention.
The fiber porous layer prepared on the surface of the electrode pole piece by adopting the spinning method can be directly integrated on the surface of the electrode pole piece, the step of independently manufacturing the isolating film in the traditional process is not needed, the production flow of the lithium ion battery can be simplified, and meanwhile, the thickness of the fiber porous layer prepared by the spinning can be made thinner, so that the energy density of the lithium ion battery can be improved; meanwhile, the fiber porous layer prepared by spinning has higher porosity than the traditional isolating film, so that the liquid retaining capacity of the lithium ion battery can be improved, and therefore, the fiber porous layer is widely paid attention to.
The defect of the porous fiber layer prepared by the prior spinning technology is obvious. When the pore diameter of the fiber porous layer is smaller, the fiber distribution is denser, the interfacial bonding force with the electrode plate is good, the capability of resisting particle penetration is stronger, but at the moment, the porosity of the fiber porous layer is lower, the ion transmission is not facilitated, and the electric performance is adversely affected after the fiber porous layer is assembled into a lithium ion battery; when the pore diameter of the fiber porous layer is larger, the fiber distribution is more sparse, the porosity is higher, the ion transmission is facilitated, the electric performance is favorably influenced after the fiber porous layer is assembled into a lithium ion battery, but the fiber porous layer is weaker in the capability of resisting particle puncture in an electrode pole piece due to the fact that the fiber porous layer is larger in porosity and lower in mechanical strength, internal short circuit is easy to occur, and the problem of overlarge self-discharge exists after the fiber porous layer is assembled into the lithium ion battery.
Disclosure of Invention
The object of the present application is to provide an electrochemical device having a porous layer provided on the surface of an electrode, which has a strong puncture resistance and a high electrochemical performance.
The first aspect of the present application provides an electrochemical device, comprising:
a first pole piece, and a first porous layer disposed on a surface of the first pole piece;
a second pole piece;
wherein the first porous layer contains first polymer fibers and first inorganic particles, in the thickness direction of the first porous layer, the average pore diameter of pores formed by the first polymer fibers in a region away from the first pole piece is a μm, the average pore diameter of pores formed by the first polymer fibers in a region close to the first pole piece is B μm, the average particle diameter of the first inorganic particles in a region away from the first pole piece is C μm, the average particle diameter of the first inorganic particles in a region close to the first pole piece is D μm, and the following relationship is satisfied:
(a)A>B;
(b)C>D。
in some embodiments of the first aspect of the present application, the first porous layer comprises a first layer that is a region proximate to the first pole piece and a second layer that is a region distal to the first pole piece.
In some embodiments of the first aspect of the present application, the value of a ranges from 0.05 to 5, the value of B ranges from 0.02 to 3, the value of C ranges from 0.01 to 10, and the value of D ranges from 0.01 to 10.
In some embodiments of the first aspect of the present application, the a, the B, the C, and the D satisfy at least one of the following relationships:
(a)1.01≤A/B≤250;
(b)1.01≤C/D≤500;
(c)0.1≤C/A≤20;
(d)0.1≤D/B≤20。
in some embodiments of the first aspect of the present application, the average particle diameter of the first inorganic particles continuously increases from a region near the first pole piece to a region distant from the first pole piece in the thickness direction of the first porous layer.
In some embodiments of the first aspect of the present application, the average pore diameter of the pores formed by the first polymer fibers continuously increases from a region near the first pole piece to a region distant from the first pole piece in the thickness direction of the first porous layer.
In some embodiments of the first aspect of the present application, wherein the first polymer fiber has a diameter of 0.1nm to 10 μm.
In some embodiments of the first aspect of the present application, the first porous layer has a porosity of 30% to 95%; the thickness of the first porous layer is 1-20 mu m.
In some embodiments of the first aspect of the present application, the weight of the first inorganic particles per unit area of the first porous layer is 0.004g/m 2 ~60g/m 2 。
In some embodiments of the first aspect of the present application, the composition of the first polymer fiber comprises at least one of polyvinylidene fluoride, polyimide, polyamide, polyacrylonitrile, polyethylene glycol, polyphenylene ether, polypropylene carbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, or polyethylene oxide.
In some embodiments of the first aspect of the present application, the first inorganic particles comprise HfO 2 、SrTiO 3 、SnO 2 、CeO 2 、MgO、NiO、CaO、BaO、ZnO、ZrO 2 、Y 2 O 3 、Al 2 O 3 、TiO 2 、SiO 2 Boehmite, magnesium hydroxide, aluminum hydroxide, lithium phosphate, lithium titanate, lithium aluminotitanate, lithium lanthanum titanate, lithium germanium thiophosphate, lithium nitride, siS 2 Glass, P 2 S 5 Glass, li 2 O、LiF、LiOH、Li 2 CO 3 、LiAlO 2 、Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 At least one of a ceramic or garnet ceramic.
In some embodiments of the first aspect of the present application, the second pole piece further comprises a second porous layer disposed on a surface of the second pole piece, the second porous layer comprising second polymer fibers and second inorganic particles, the second polymer fibers forming pores having an average pore size of E μm, the second inorganic particles having an average particle size of F μm and satisfying the following relationship:
(a)A>E;
(b)C>F。
In some embodiments of the first aspect of the present application, the first porous layer and the second porous layer are in contact.
A second aspect of the present application provides an electronic device comprising the electrochemical device provided in the first aspect of the present application.
According to the electrochemical device provided by the scheme of the application, the porous layer is arranged on the surface of the pole piece, the pore diameter of the area close to the pole piece is small, and the fibers are densely distributed, so that the adhesion force with the pole piece is strong, and the capability of resisting the penetration of positive and negative particles is strong; the aperture of the area far away from the pole piece is large, the ion conduction capacity is strong, and the electric performance of the electrochemical device is improved; inorganic particles with different particle diameters are adopted to fill in areas with different pore diameters, so that the mechanical strength of the porous layer is further improved, the pore diameter distribution of the porous layer is optimized, the average pore diameter is reduced, and the self-discharge problem of an electrochemical device is further improved.
In the present application, the term "average particle diameter" means Dv50, and Dv50 means a particle diameter of 50% by volume from the small particle diameter side in the particle size distribution based on the volume of the inorganic particles.
Drawings
In order to more clearly illustrate the embodiments of the present application and the technical solutions of the prior art, the following description of the embodiments and the drawings required in the prior art will briefly describe, it should be apparent that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.
Fig. 1 is an SEM image of a second layer of the first porous layer of the electrochemical device of example 1.
Detailed Description
For the purposes of making the objects, technical solutions, and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.
The electrochemical device of the present application may be any electrochemical device using a pole piece and a porous layer, such as a lithium ion battery, a supercapacitor, etc., and will be described below by taking a lithium ion battery as an example. It is to be understood by persons skilled in the art that the following descriptions are exemplary only and are not intended to limit the scope of the present application.
The first aspect of the present application provides an electrochemical device, comprising:
a first pole piece, and a first porous layer disposed on a surface of the first pole piece;
a second pole piece;
wherein the first porous layer contains first polymer fibers and first inorganic particles, in the thickness direction of the first porous layer, the average pore diameter of pores formed by the first polymer fibers in a region away from the first pole piece is a μm, the average pore diameter of pores formed by the first polymer fibers in a region close to the first pole piece is B μm, the average particle diameter of the first inorganic particles in a region away from the first pole piece is C μm, the average particle diameter of the first inorganic particles in a region close to the first pole piece is D μm, and the following relationship is satisfied:
(a)A>B;
(b)C>D。
The electrochemical device comprises a positive electrode plate and a negative electrode plate, wherein the first electrode plate can be the positive electrode plate or the negative electrode plate; the first porous layer can be arranged on the surface of the positive electrode plate or the surface of the negative electrode plate; the first porous layer may be disposed on one surface of the positive electrode sheet and the negative electrode sheet, or may be formed on both surfaces of the positive electrode sheet or the negative electrode sheet.
In the application, the first porous layer is formed on the first pole piece, one surface of the first porous layer is contacted with the first pole piece, and the other surface of the first porous layer is not contacted with the first pole piece; the 'area close to the first pole piece' refers to an area of the porous layer extending from one surface contacted with the first pole piece to the middle of the porous layer, and the thickness of the porous layer can be 10% -90% of the thickness of the porous layer; the 'region far away from the first pole piece' refers to a region extending from one surface of the porous layer, which is not contacted with the first pole piece, to the middle part of the porous layer, and the thickness of the region can be 10% -90% of the thickness of the porous layer; the area close to the first pole piece and the area far away from the first pole piece can be directly connected, and an intermediate area can be further included between the area close to the first pole piece and the area far away from the first pole piece, the average pore diameter of the intermediate area is not limited in the application, and the pore diameter of the intermediate area can be between A and B.
The porous layer in the present application is composed of polymer fibers forming a porous matrix in which the inorganic particles are distributed. In the present application, the pore size of pores formed by the polymer fibers in different regions is understood to be the pore size of the porous matrix in different regions. The inventor finds in the study that, without being limited by any theory, the porous layer of the application has smaller average pore diameter of the porous matrix in the area close to the first pole piece, and the polymer fibers are densely distributed, so that high adhesion with the pole piece can be realized, and the capability of resisting the penetration of positive and negative particles is ensured; and the area far away from the first pole piece is provided with larger average pore diameter of the porous matrix, and polymer fibers are loose in distribution, so that high ion conductivity is provided. Meanwhile, the inorganic particles with the particle size matched with the pore size of the porous matrix are filled, so that the gaps of the porous matrix can be effectively filled, the mechanical strength of the porous layer is further improved, the pore size distribution of the porous layer is optimized, the average pore size is reduced, and the self-discharge problem of the electrochemical device is further improved.
In some embodiments of the first aspect of the present application, 1.01.ltoreq.A/B.ltoreq.250.
In some embodiments of the first aspect of the present application, 1.01.ltoreq.C/D.ltoreq.500.
The average pore diameter of the polymer fibers formed in the different regions is not particularly limited as long as the object of the present application can be achieved; for example, the average pore diameter of the pores formed by the first polymer fibers in the region far away from the first pole piece can be 50nm to 5 μm, namely, the value of A is in the range of 0.05 to 5; the average pore diameter of the pores formed by the first polymer fibers in the area close to the first pole piece can be 20 nm-3 mu m, and the value range of B is 0.02-3.
The average particle diameter of the inorganic particles is not particularly limited as long as the object of the present application can be achieved; for example, the average particle size of the first inorganic particles in the region far from the first pole piece may be 10nm to 10 μm, that is, the value of C is in the range of 0.01 to 10, and the average particle size of the first inorganic particles in the region near to the first pole piece may be 10nm to 10 μm, that is, the value of D is in the range of 0.01 to 10.
The inventor also discovers that in different areas, a certain matching relation needs to be provided between the average particle diameter of the inorganic particles and the average pore diameter of the porous matrix, and if the average particle diameter of the inorganic particles is too small, the pores of the porous matrix cannot be effectively filled, and the purposes of improving the mechanical strength of the porous layer and reducing the average pore diameter of the porous layer cannot be achieved; the average particle size of the inorganic particles is too large, so that the pores of the porous matrix of the porous layer cannot be filled effectively, the whole thickness of the porous layer is enlarged, and the thickness uniformity is destroyed; in some embodiments of the first aspect of the present application, 0.1.ltoreq.C/A.ltoreq.20; preferably 0.5.ltoreq.C/A.ltoreq.3.0; more preferably 1.5; in other embodiments of the first aspect of the present application, 0.1.ltoreq.D/B.ltoreq.20; preferably 0.5 to 3.0; more preferably 1.5.
In some embodiments of the first aspect of the present application, the average particle size of the first inorganic particles continuously increases from a region near the first pole piece to a region far from the first pole piece in the thickness direction of the first porous layer; for example, the pore size of the porous matrix may be changed in a gradient manner by linear or nonlinear increase: the small-aperture area gradually transits to the mixed area of the large aperture and the small aperture, and then transits to the large-aperture area, and the large-aperture area and the small-aperture area have no obvious interface.
In some embodiments of the first aspect of the present application, the average particle diameter of the first inorganic particles continuously increases from a region near the first pole piece to a region distant from the first pole piece in the thickness direction of the first porous layer.
In some embodiments of the first aspect of the present application, the first porous layer comprises a first layer that is a region proximate to the first pole piece and a second layer that is a region distal to the first pole piece.
In other embodiments of the first aspect of the present application, the first porous layer further includes an intermediate layer, where the intermediate layer is located between the first layer and the second layer, and the average pore size layers of the first layer, the intermediate layer, and the second layer sequentially increase, which is understood to mean that the change in average pore size of the porous matrix is a sharp change, that is, the large pore size region has a distinct interface with the small pore size region. In some embodiments of the first aspect of the present application, the first polymer fibers have a diameter of 0.1nm to 10 μm. The diameter of the polymer fiber is too small, the strength of the fiber is too low, the polymer fiber is easily broken in the preparation or use process of the lithium ion battery, and the porous layer is pierced by positive and negative electrode active material particles to generate self-discharge; too large a diameter of the polymer fibers occupies too large a volume of the porous layer, which may result in too large a pore size of the porous layer when the porous layer contains the same weight of nanofibers. In the case where the porous layer maintains the same porosity, the nanofiber content decreases, resulting in a decrease in the strength of the porous layer and an excessive pore size.
In some embodiments of the first aspect of the present application, the first porous layer has a porosity of 30% to 95%. The inventor finds that too small porosity can cause the blockage of an ion transmission channel to prevent the normal charge and discharge of the electrochemical device in the research; too high porosity can lead to unstable porous layer structure, too poor mechanical strength and incapability of resisting penetration of particles on the surface of the pole piece.
The thickness of the first porous layer is not particularly limited, and is preferably smaller than that of the prior art separator, for example, the thickness of the porous layer of the present application may be 1 μm to 20 μm, and preferably 5 μm to 10 μm. The first porous layer has a small thickness, and can improve the energy density of the electrochemical device.
In some implementations of the first aspect of the present applicationIn this manner, the weight of the first inorganic particles per unit area of the first porous layer is 0.004g/m 2 ~60g/m 2 。
The polymer type of the first polymer fiber is not particularly limited as long as the first porous layer of the present application can be formed. For example, the composition of the first polymer fiber may include at least one of polyvinylidene fluoride (PVDF), polyimide (PI), polyamide (PA), polyacrylonitrile (PAN), polyethylene glycol (PEG), polyphenylene ether (PPE), polypropylene carbonate (PPC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-chlorotrifluoroethylene, polyethylene oxide (PEO), or derivatives; preferably at least one of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyphenylene oxide (PPO), polypropylene carbonate (PPC), polyethylene oxide (PEO). These polymers may be used singly or in combination of two or more.
The first inorganic particles are not particularly limited and may be selected from, for example, hfO 2 、SrTiO 3 、SnO 2 、CeO 2 、MgO、NiO、CaO、BaO、ZnO、ZrO 2 、Y 2 O 3 、Al 2 O 3 、TiO 2 、SiO 2 Boehmite, magnesium hydroxide, aluminum hydroxide, lithium phosphate (Li) 3 PO 4 ) Lithium titanium phosphate (Li) x Ti y (PO 4 ) 3 Wherein 0 < x < 2 and 0 < y < 3), lithium aluminum titanium phosphate (Li) x Al y Ti z (PO 4 ) 3 Wherein 0 < x < 2,0 < y < 1, and 0 < z < 3), li 1+x+y (Al,Ga) x (Ti,Ge) 2-x Si y P 3-y O 12 Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and lithium lanthanum titanate (Li) x La y TiO 3 Wherein 0 < x < 2 and 0 < y < 3), lithium germanium thiophosphate (Li) x Ge y P z S w Wherein 0 < x < 4,0 < y < 1,0 < z < 1, and 0 < w < 5), lithium nitride (Li x N y Wherein 0 < >x<4,0<y<2)、SiS 2 Glass (Li) x Si y S z Wherein 0.ltoreq.x < 3,0 < y < 2, and 0 < z < 4), P 2 S 5 Glass (Li) x P y S z Wherein 0.ltoreq.x < 3,0 < y < 3, and 0 < z < 7), li 2 O、LiF、LiOH、Li 2 CO 3 、LiAlO 2 、Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 Ceramic or garnet ceramic (Li) 3+x La 3 M 2 O 12 Wherein 0.ltoreq.x.ltoreq.5, and M is any one or a mixture of at least two of Te, nb, or Zr).
In some embodiments of the first aspect of the present application, the second pole piece further comprises a second porous layer disposed on a surface of the second pole piece, the second porous layer comprising second polymer fibers and second inorganic particles, the second polymer fibers forming pores having an average pore size of E μm, the second inorganic particles having an average particle size of F μm and satisfying the following relationship:
(a)A>E;
(b)C>F。
In the application, the first porous layer can be directly obtained by processing the surface of the first pole piece, and is contacted and bonded with the second pole piece when the electrochemical device is assembled; in a preferred embodiment of the present application, the second porous layer is provided on the surface of the second electrode sheet, and the second porous layer is in contact with the first porous layer when the electrochemical device is assembled, so that the adhesion between the electrode sheet and the porous layer can be further improved.
In some embodiments of the first aspect of the present application, the second polymer fibers may have a diameter of 0.1nm to 10 μm. The second polymer fibers may have the same or different diameters than the first polymer fibers.
In some embodiments of the first aspect of the present application, the second porous layer has a porosity of 30% to 95%. The second porous layer may have the same or different porosity as the first porous layer.
The thickness of the second porous layer is not particularly limited, and may be, for example, 1 μm to 5 μm.
The weight of the second inorganic particles in the second porous layer is not particularly limited, and may be, for example, 0.004g/m 2 ~60g/m 2 The weight of the second inorganic particles may be the same as or different from the weight of the first inorganic particles.
The polymer type of the second polymer fiber is not particularly limited as long as the second porous layer of the present application can be formed. For example, the composition of the second polymer fiber may include at least one of polyvinylidene fluoride (PVDF), polyimide (PI), polyamide (PA), polyacrylonitrile (PAN), polyethylene glycol (PEG), polyphenylene ether (PPE), polypropylene carbonate (PPC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-chlorotrifluoroethylene, polyethylene oxide (PEO), or derivatives; preferably at least one of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyphenylene oxide (PPO), polypropylene carbonate (PPC), polyethylene oxide (PEO). These polymers may be used singly or in combination of two or more kinds thereof. The polymer used for the second polymer fibers may be the same as or different from the first polymer fibers.
The second inorganic particles are not particularly limited and may be selected from, for example, hfO 2 、SrTiO 3 、SnO 2 、CeO 2 、MgO、NiO、CaO、BaO、ZnO、ZrO 2 、Y 2 O 3 、Al 2 O 3 、TiO 2 、SiO 2 Boehmite, magnesium hydroxide, aluminum hydroxide, lithium phosphate (Li) 3 PO 4 ) Lithium titanium phosphate (Li) x Ti y (PO 4 ) 3 Wherein 0 < x < 2 and 0 < y < 3), lithium aluminum titanium phosphate (Li) x Al y Ti z (PO 4 ) 3 Wherein 0 < x < 2,0 < y < 1, and 0 < z < 3), li 1+x+y (Al,Ga) x (Ti,Ge) 2-x Si y P 3-y O 12 Wherein x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, and lithium lanthanum titanate (Li) x La y TiO 3 Wherein 0 < x < 2 and 0 < y < 3), lithium germanium thiophosphate (Li) x Ge y P z S w Wherein 0 < x < 4,0 < y < 1,0 < z < 1, and 0 < w < 5), lithium nitride (Li x N y Wherein x is more than 0 and less than 4, y is more than 0 and less than 2), siS 2 Glass (Li) x Si y S z Wherein 0.ltoreq.x < 3,0 < y < 2, and 0 < z < 4), P 2 S 5 Glass (Li) x P y S z Wherein 0.ltoreq.x < 3,0 < y < 3, and 0 < z < 7), li 2 O、LiF、LiOH、Li 2 CO 3 、LiAlO 2 、Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 Ceramic or garnet ceramic (Li) 3+x La 3 M 2 O 12 Wherein 0.ltoreq.x.ltoreq.5, and M is any one or a mixture of at least two of Te, nb, or Zr).
In the electrochemical device of the present application, the second inorganic particles may be the same as or different from the first inorganic particles.
In the present application, the method of depositing the polymer fibers and the inorganic particles is not particularly limited, and may be performed using a deposition method well known in the art, for example, the porous matrix is prepared by electrospinning, gas spinning, or centrifugal spinning, and the inorganic particles are filled in the porous matrix by the electrodeposition method. The order of depositing the polymer fibers and the inorganic particles is not particularly limited as long as the porous layer of the present application is formed, and the porous layer of the present application includes a porous matrix formed of polymer fibers and inorganic particles distributed in the porous matrix. For example, the polymer fibers and the inorganic particles of the corresponding particle size may be deposited simultaneously.
The porous layer of the present application may be carried out with any spinning apparatus known in the art, without particular limitation, as long as the object of the present application can be achieved, any spinning apparatus known in the art may be used, for example, the electrospinning apparatus may be of the Elite series of Yongkangle industry or the like; the air spinning equipment can be an air jet spinning machine and the like for Nanjing Jiesnano new materials; the centrifugal spinning equipment can be a centrifugal spinning machine of Sichuan research technology and the like. The electrodeposition method may be carried out with any apparatus known in the art, and is not particularly limited as long as the object of the present application can be achieved. For example, an electrostatic spraying device of samis, france may be used.
The type of lithium ion battery according to the present application is not limited, and may be any type of lithium ion battery, such as button type, cylindrical type, soft pack type lithium ion battery, and the like. A lithium ion battery according to the present application includes a positive electrode, a negative electrode, an electrolyte, and a porous layer according to the present application. In one embodiment of the present application, the first porous layer may be formed on both surfaces of the positive electrode tab, and then laminated in such a manner that the negative electrode tab, the first porous layer, the positive electrode tab, and the first porous layer form a lithium ion battery laminate, in which the negative electrode tab has no porous layer on the surface. In another embodiment of the present application, the first porous layer may be formed on both surfaces of the negative electrode tab, and then laminated in such a manner that the first porous layer+the negative electrode tab+the first porous layer, the positive electrode tab, to form a lithium ion battery laminate. In other embodiments of the present application, a first porous layer may be formed on both surfaces of the positive electrode sheet, a second porous layer is formed on the negative electrode sheet, and then laminated in such a manner that the second porous layer+the negative electrode sheet+the second porous layer, the first porous layer+the positive electrode sheet+the first porous layer, to form a lithium ion battery laminate; or the first porous layer is formed on two surfaces of the negative electrode plate, the second porous layer is formed on the positive electrode plate, and then the lithium ion battery laminated body is formed by laminating the second porous layer, the positive electrode plate, the second porous layer, the first porous layer, the negative electrode plate and the first porous layer. The laminate formed in the above embodiment may be continuously laminated in the above order, or may be directly wound to form a multi-layered lithium ion battery laminate. The lamination method is not limited in this application, and those skilled in the art can select according to the actual situation.
In the embodiment of the present application, the positive electrode sheet is not particularly limited as long as the object of the present application can be achieved. For example, the positive electrode sheet generally includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material. The positive electrode collector is not particularly limited, and may be any positive electrode collector known in the art, such as copper foil, aluminum alloy foil, composite collector, and the like. The positive electrode active material is not particularly limited, and may be any positive electrode active material of the prior art, for example, the active material is selected from at least one of lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium cobalt oxide, lithium manganate, lithium manganese iron phosphate.
Optionally, the positive electrode sheet may further include a conductive layer between the positive electrode current collector and the positive electrode active material. The composition of the conductive layer is not particularly limited, and may be a conductive layer commonly used in the art.
In the embodiments of the present application, the negative electrode tab is not particularly limited as long as the object of the present application can be achieved. For example, the negative electrode tab typically includes a negative electrode current collector and a negative electrode active material layer, the positive electrode active material layer including a positive electrode active material. The negative electrode collector is not particularly limited, and any negative electrode collector known in the art, such as copper foil, aluminum alloy foil, composite collector, and the like, may be used. The anode active material is not particularly limited, and any anode active material known in the art may be used. For example, at least one of artificial graphite, natural graphite, mesophase carbon microspheres, silicon carbon, silicon oxygen compounds, soft carbon, hard carbon, lithium titanate, niobium titanate, or the like may be included.
The electrolyte of the lithium ion battery is not particularly limited, and any electrolyte known in the art, which may be any of gel state, solid state, and liquid state, may be used. For example, the liquid electrolyte includes a lithium salt and a nonaqueous solvent.
The lithium salt is not particularly limited, and any lithium salt known in the art may be used as long as the object of the present application can be achieved. For example, the lithium salt may be selected from LiPF 6 、LiBF 4 、LiAsF 6 、LiClO 4 、LiB(C 6 H 5 ) 4 、LiCH 3 SO 3 、LiCF 3 SO 3 、LiN(SO 2 CF 3 ) 2 、LiC(8O 2 CF 3 ) 3 And LiPO 2 F 2 At least one of them. For example, the lithium salt may be LiPF 6 。
The nonaqueous solvent is not particularly limited as long as the object of the present application can be achieved. For example, the nonaqueous solvent may be at least one selected from a carbonate compound, a carboxylate compound, an ether compound, a nitrile compound, and other organic solvents.
For example, the carbonate compound may be selected from at least one of diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylene Propylene Carbonate (EPC), methylethyl carbonate (MEC), ethylene Carbonate (EC), propylene Carbonate (PC), butylene Carbonate (BC), vinyl Ethylene Carbonate (VEC), fluoroethylene carbonate (FEC), 1, 2-difluoroethylene carbonate, 1, 2-trifluoroethylene carbonate, 1, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-difluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, and trifluoromethyl ethylene carbonate.
Another aspect of the present application provides an electronic device comprising an electrochemical device according to the present application.
The testing method comprises the following steps:
weight of inorganic particles in porous layer per unit area:
disassembling the lithium ion battery after discharging to obtain an electrode plate with a porous layer on the surface, wherein the intercepting area is S m 2 The inorganic particles in the sample are then separated, dried at 110 ℃, and then weighed to give a weight of mg, m/S, which is the weight of inorganic particles in the porous layer per unit area.
Porosity of porous layer:
and (3) after discharging the lithium ion battery, disassembling the lithium ion battery to obtain an electrode plate with a porous layer on the surface, intercepting a part of porous layer samples, and testing the porosity of the porous layer by a conventional mercury intrusion method.
Self-discharge rate K value of lithium ion battery:
the lithium ion battery was discharged to 3.0V at a current of 0.5C, left standing for 5min, then charged to 3.85V at a constant current of 0.5C, then charged to 0.05C at a constant voltage of 3.85V, left standing for two days in an environment of 25 ℃ ± 3 ℃, and the voltage OCV1 at this time was tested and recorded. Then, the lithium ion battery is kept still in an environment of 25+/-3 ℃ for two days, the voltage OCV2 at the moment is tested and recorded, and the K value is obtained through the following formula: k (mV/h) = (OCV 2-OCV 1)/48 h×1000.
Capacity retention rate:
charging lithium ion battery to 4.4V at constant current of 0.5C, charging to 0.05C at constant voltage of 4.4V, standing at 25deg.C+ -3deg.C for 10min, discharging to 3.0V at current of 0.5C, and recording first discharge capacity as Q 1 The cycle was repeated 50 times, and the discharge capacity was recorded as Q at this time 50 The capacity retention η after 50 cycles is obtained by the following formula: η=q 50 /Q 1 *100%。
Examples
Preparation example 1: preparation of negative electrode plate
Mixing the negative electrode active material artificial graphite, conductive carbon black and styrene-butadiene rubber according to the weight ratio of 96:1.5:2.5, adding deionized water as a solvent, preparing into slurry with the solid content of 0.7, and uniformly stirring. The slurry was uniformly coated on one surface of a copper foil of a negative electrode current collector having a thickness of 10 μm, and dried at 110 deg.c to obtain a negative electrode tab having a single-sided coated negative electrode active material layer having a thickness of 150 μm. The above procedure was repeated on the other surface of the negative electrode collector, to obtain a negative electrode tab double-coated with a negative electrode active material layer 150 μm thick. Then, the negative electrode sheet was cut into 41mm by 61mm specifications for use.
Preparation example 2: preparation of positive electrode plate
Mixing positive active materials of lithium cobaltate, conductive carbon black and polyvinylidene fluoride according to the weight ratio of 97.5:1.0:1.5, adding N-methyl pyrrolidone (NMP) as a solvent, preparing into slurry with the solid content of 0.75, and uniformly stirring. The slurry was uniformly coated on one surface of an aluminum foil of a positive electrode current collector, and dried at 90 deg.c to form a positive electrode active material layer having a thickness of 100 μm on one surface of the positive electrode current collector. The above steps were repeated on the other surface of the positive electrode current collector aluminum foil, to obtain a positive electrode tab double-coated with a 100 μm positive electrode active material layer. After the coating is finished, the positive pole piece is cut into the specification of 38mm multiplied by 58mm for standby.
Preparation example 3: preparation of electrolyte
In a dry argon atmosphere, firstly, mixing Ethylene Carbonate (EC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) into a solvent according to the mass ratio of EC to EMC to DEC=30 to 50 to 20, then adding lithium hexafluorophosphate into the solvent, dissolving and uniformly mixing to obtain the electrolyte with the lithium salt concentration of 1.15 mol/L.
The following examples illustrate the preparation of porous layers according to the present application. These embodiments are described taking the negative electrode tab as an example, and depositing a first porous layer on both surfaces of the negative electrode tab. It should be understood that the first porous layer may be deposited on both surfaces of the positive electrode tab, or a first porous layer may be deposited on one surface of the negative electrode tab and one surface of the positive electrode tab, respectively, which embodiments may also achieve the objects of the present application. Those skilled in the art will appreciate that these embodiments are also within the scope of the present application.
Example 1
Preparation of slurry A: the first inorganic particles of aluminum oxide (Al 2 O 3 ) And polyvinylidene fluoride (PVDF) as binder, mixing according to the weight ratio of 90:10, adding N-methyl pyrrolidone (NMP) as solvent, and preparing into slurry A with solid content of 0.4, wherein the average particle size of the first inorganic particles is 60nm.
Preparation of slurry B: the first inorganic particles of aluminum oxide (Al 2 O 3 ) And polyvinylidene fluoride (PVDF) as binder, mixing according to the weight ratio of 90:10, adding N-methyl pyrrolidone (NMP) as solvent, and preparing into slurry B with solid content of 0.4, wherein the average particle size of the first inorganic particles is 300nm.
Dispersing polyvinylidene fluoride in a dimethylformamide/acetone (7:3) solvent, uniformly stirring until the viscosity of slurry is stable, obtaining a solution with the mass fraction of 25%, and preparing a first layer with the thickness of 3 mu m and the average pore diameter of 20nm on one surface of the negative electrode plate obtained in preparation example 1 by using the solution through an electrospinning method; while electrospinning, using the slurry A as a raw material, and adopting an electrospraying method to obtain the final product 2 O 3 The particles are filled in the first layer, wherein, al 2 O 3 The average particle diameter of the particles is 60nm; then preparing a second layer with the thickness of 9 mu m and the average pore diameter of 100nm on the upper part by a gas spinning method, and simultaneously taking the slurry B as a raw material and adopting an electrospraying method to obtain the Al-doped aluminum alloy 2 O 3 The particles are filled in the second layer, wherein, al 2 O 3 The particles had an average particle diameter of 300nm (a second layer micrograph of the first porous layer is shown in FIG. 1);
wherein the polymer fibers (component PVDF) in each of the first and second layers have a diameter of 100nm, the first porous layer formed from the first and second layers has a porosity of 80%, and the first inorganic particles in the first porous layer formed from the first and second layers have a weight per unit area of 4.5g/m 2 。
And (3) finishing the steps on the other surface of the negative electrode plate by a completely consistent method to obtain the negative electrode plate with the first porous layer coated on both sides.
Preparing a second porous layer (PVDF) with a thickness of 3 μm and an average pore diameter of 20nm on one surface of the positive electrode sheet obtained in preparation example 2 by electrospinning, and filling Al between the second polymer fibers by electrospraying while spinning by using a slurry A 2 O 3 Inorganic particles having an average particle diameter of 60nm;
wherein the diameter of the polymer fibers of the second porous layer is 100nm; the second porous layer had a porosity of 80%.
And (3) finishing the steps on the other surface of the positive electrode plate by a completely consistent method to obtain the positive electrode plate with the double-sided coating.
Example 2
The average particle diameter of the inorganic particles filled in the first layer of the first porous layer except the surface of the negative electrode plate is 400nm; the average particle diameter of the inorganic particles filled in the second layer is 2000nm;
the average particle diameter of the inorganic particles filled in the second porous layer on the surface of the positive electrode plate is 400nm;
the remainder was the same as in example 1.
Example 3
The average pore diameter of the first porous layer except the surface of the negative electrode plate is 50nm, and the average particle diameter of the filled inorganic particles is 100nm; the average pore diameter of the second layer is 500nm, and the average particle diameter of the filling inorganic particles is 1000nm;
the average pore diameter of the second porous layer on the surface of the positive electrode plate is 50nm, and the average particle diameter of the filling inorganic particles is 100nm;
the remainder was the same as in example 1.
Example 4
The average pore diameter of the second layer except the first porous layer of the negative electrode plate is 1000nm, and the average particle diameter of the filling inorganic particles is 2000nm; the remainder was the same as in example 3.
Example 5
Except that the average pore diameter of the second layer of the first porous layer of the negative electrode plate is 5000nm, and the average particle diameter of the filling inorganic particles is 10000nm; the remainder was the same as in example 3.
Example 6
The average pore diameter of the first layer of the first porous layer except the surface of the negative electrode plate is 80nm, and the average particle diameter of the filling inorganic particles is 300nm; the average pore diameter of the second fiber layer is 400nm, and the average particle diameter of the filling inorganic particles is 1500nm;
The average pore diameter of the second porous layer on the surface of the positive electrode plate is 80nm, and the average particle diameter of the filling inorganic particles is 300nm;
the remainder was the same as in example 1.
Example 7
The average pore diameter of a layer of the first porous layer except the surface of the negative electrode plate is 100nm, and the average particle diameter of the filling inorganic particles is 10nm; the average pore diameter of the second layer is 1000nm, and the average particle diameter of the filling inorganic particles is 100nm;
the average pore diameter of the second porous layer on the surface of the positive electrode plate is 100nm, and the average particle diameter of the filling inorganic particles is 10nm;
the remainder was the same as in example 1.
Example 8
The average pore diameter of the first porous layer except the surface of the negative electrode plate is 100nm, and the average particle diameter of the filling inorganic particles is 200nm; the average pore diameter of the second fiber layer is 500nm, and the average particle diameter of the filling inorganic particles is 1000nm;
the average pore diameter of the second porous layer on the surface of the positive electrode plate is 100nm, and the average particle diameter of the filling inorganic particles is 200nm;
the remainder was the same as in example 1.
Example 9
The average pore diameter of the first porous layer except the surface of the negative electrode plate is 120nm, and the average particle diameter of the filling inorganic particles is 12nm; the average pore diameter of the second layer is 600nm, and the average particle diameter of the filling inorganic particles is 60nm;
The average pore diameter of the second porous layer on the surface of the positive electrode plate is 120nm, and the average particle diameter of the filling inorganic particles is 12nm;
the remainder was the same as in example 1.
Example 10
The average particle diameter of the inorganic particles filled in the first layer except the first porous layer on the negative electrode plate is 120nm, and the average particle diameter of the inorganic particles filled in the second layer is 600nm;
the average particle diameter of inorganic particles filled in the second porous layer on the surface of the positive electrode plate is 120nm;
the remainder was the same as in example 9.
Example 11
The average particle diameter of the inorganic particles filled in the first layer except the first porous layer on the negative electrode plate is 400nm, and the average particle diameter of the inorganic particles filled in the second layer is 2000nm;
the average particle diameter of inorganic particles filled in the second porous layer on the surface of the positive electrode plate is 400nm;
the remainder was the same as in example 9.
Example 12
The average particle diameter of the inorganic particles filled in the first layer except the first porous layer on the negative electrode plate is 1200nm, and the average particle diameter of the inorganic particles filled in the second layer is 6000nm;
the average particle diameter of inorganic particles filled in the second porous layer on the surface of the positive electrode plate is 1200nm;
the remainder was the same as in example 9.
Example 13
The average pore diameter of the first porous layer except the surface of the negative electrode plate is 180nm, and the average particle diameter of the filling inorganic particles is 2000m; the average pore diameter of the second layer is 500nm, and the average particle diameter of the filling inorganic particles is 10000nm;
The average pore diameter of the second porous layer on the surface of the positive electrode plate is 180nm, and the average particle diameter of the filling inorganic particles is 2000nm;
the remainder was the same as in example 1.
Example 14
The average pore diameter of the first porous layer except the surface of the negative electrode plate is 1000nm, and the average particle diameter of the filling inorganic particles is 100m; the average pore diameter of the second layer is 5000nm, and the average particle diameter of the filling inorganic particles is 5000nm;
the average pore diameter of the second porous layer on the surface of the positive electrode plate is 1000nm, and the average particle diameter of the filling inorganic particles is 100nm;
the remainder was the same as in example 1.
Example 15
The average pore diameter of the first porous layer except the surface of the negative electrode plate is 3000nm, and the average particle diameter of the filled inorganic particles is 8000m; the average pore diameter of the second layer is 5000nm, and the average particle diameter of the filling inorganic particles is 10000nm;
the average pore diameter of the second porous layer on the surface of the positive electrode plate is 3000nm, and the average particle diameter of the filling inorganic particles is 8000nm;
the remainder was the same as in example 1.
Example 16
The procedure of example 6 was repeated except that the second porous layer was not provided.
Example 17
Except that the weight of the inorganic particles in the first porous layer was controlled to be 4mg/m 2 ;
The remainder was the same as in example 6.
Example 18
Except that the weight of the inorganic particles in the first porous layer was controlled to be 60g/m 2 ;
The remainder was the same as in example 6.
Example 19
The procedure of example 6 was repeated except that Polyacrylonitrile (PAN) was used as a raw material to prepare the first porous layer and the second porous layer.
Example 20
The procedure of example 6 was repeated except that polyethylene oxide (PEO) was used as a raw material to prepare a first porous layer and a second porous layer.
Full cell preparation:
the negative electrode sheet with the first porous layer prepared in each example and the positive electrode sheet prepared in the preparation example were opposed and stacked. And fixing four corners of the whole lamination structure by using an adhesive tape, then placing the lamination structure into an aluminum plastic film, and finally obtaining the lithium ion lamination battery after top side sealing, liquid injection and encapsulation.
Comparative example 1
No inorganic particles are filled in both the first porous layer and the second porous layer; the remainder was the same as in example 11.
Comparative example 2
Except that the first layer, the second layer and the second porous layer of the first porous layer are each filled with inorganic particles having an average particle diameter of 2000 nm; the remainder was the same as in example 11.
Comparative example 3
Except that the first layer, the second layer and the second porous layer of the first porous layer are each filled with inorganic particles having an average particle diameter of 400 nm; the remainder was the same as in example 11.
Comparative example 4
Inorganic particles with the average particle diameter of 80nm are filled in a first layer of the first porous layer except the surface of the negative electrode plate; the remainder was the same as in example 14.
Comparative example 5
Inorganic particles with average particle diameter of 2500nm are filled in a second layer of the first porous layer except the surface of the negative electrode plate; the remainder was the same as in example 2.
The data and test results for each example and comparative example are shown in Table 1.
As can be seen from example 11 of the present application, when inorganic particles of different particle diameters are filled into regions of different pore diameters of the porous layer, the self-discharge problem is significantly improved (K value is reduced) as compared with comparative examples 1, 2, 3; the cycle performance of the battery is also improved (cycle capacity retention rate is high).
Example 14 compared with comparative example 4, example 2 compared with comparative example 5, it can be seen that when the particle size of the filled inorganic particles is too large or too small, neither the self-discharge problem nor the cycle performance is well improved, but only when the ratio of the particle size of the filled inorganic particles to the pore size of the porous layer satisfies 0.1 to 20, both the self-discharge problem and the cycle efficiency are improved or enhanced.
The foregoing description of the preferred embodiments of the present invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, alternatives, and alternatives falling within the spirit and scope of the invention.
Claims (13)
1. An electrochemical device, comprising:
a first pole piece, and a first porous layer disposed on a surface of the first pole piece;
a second pole piece;
wherein the first porous layer contains first polymer fibers and first inorganic particles, in the thickness direction of the first porous layer, the average pore diameter of pores formed by the first polymer fibers in a region away from the first pole piece is a μm, the average pore diameter of pores formed by the first polymer fibers in a region close to the first pole piece is B μm, the average particle diameter of the first inorganic particles in a region away from the first pole piece is C μm, the average particle diameter of the first inorganic particles in a region close to the first pole piece is D μm, and the following relationship is satisfied:
(a) A is greater than B, the value range of A is 0.05-5, and the value range of B is 0.02-3;
(b) C > D, the value range of C is 0.06-10, and the value range of D is 0.01-8.
2. The electrochemical device of claim 1, wherein the first porous layer comprises a first layer that is a region proximate to the first pole piece and a second layer that is a region distal from the first pole piece.
3. The electrochemical device of any one of claims 1-2, wherein the a, the B, the C, and the D satisfy at least one of the following relationships:
(a)1.01≤A/B≤250;
(b)1.01≤C/D≤500;
(c)0.1≤C/A≤20;
(d)0.1≤D/B≤20。
4. the electrochemical device according to claim 1, wherein an average particle diameter of the first inorganic particles continuously increases from a region close to the first electrode sheet to a region distant from the first electrode sheet in a thickness direction of the first porous layer.
5. The electrochemical device according to claim 1, wherein an average pore diameter of pores formed by the first polymer fibers continuously increases from a region near the first electrode sheet to a region distant from the first electrode sheet in a thickness direction of the first porous layer.
6. The electrochemical device according to claim 1, wherein the first polymer fiber has a diameter of 0.1nm to 10 μm.
7. The electrochemical device according to claim 1, wherein,
the porosity of the first porous layer is 30% -95%; the thickness of the first porous layer is 1-20 mu m.
8. The electrochemical device according to claim 1, wherein the weight of the first inorganic particles per unit area of the first porous layer is 0.004g/m 2 ~60g/m 2 。
9. The electrochemical device of claim 1, wherein the first polymer fiber comprises at least one of polyvinylidene fluoride, polyimide, polyamide, polyacrylonitrile, polyethylene glycol, polyphenylene oxide, polypropylene carbonate, polymethyl methacrylate, polyethylene terephthalate, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, or polyethylene oxide.
10. The electrochemical device of claim 1, wherein the first inorganic particles comprise HfO 2 、SrTiO 3 、SnO 2 、CeO 2 、MgO、NiO、CaO、BaO、ZnO、ZrO 2 、Y 2 O 3 、Al 2 O 3 、TiO 2 、SiO 2 Boehmite, magnesium hydroxide, aluminum hydroxide, lithium phosphate, lithium titanate, lithium aluminotitanate, lithium lanthanum titanate, lithium germanium thiophosphate, lithium nitride, siS 2 Glass, P 2 S 5 Glass, li 2 O、LiF、LiOH、Li 2 CO 3 、LiAlO 2 、Li 2 O-Al 2 O 3 -SiO 2 -P 2 O 5 -TiO 2 -GeO 2 At least one of a ceramic or garnet ceramic.
11. The electrochemical device of claim 1, wherein the second electrode sheet further comprises a second porous layer disposed on a surface of the second electrode sheet, the second porous layer comprising second polymer fibers and second inorganic particles, the second polymer fibers forming pores having an average pore diameter of E μιη, the second inorganic particles having an average particle diameter of F μιη and satisfying the following relationship:
(a)A>E;
(b)C>F。
12. The electrochemical device of claim 11, wherein the first porous layer and the second porous layer are in contact.
13. An electronic device comprising the electrochemical device of any one of claims 1-12.
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