CN117832758A - Solid electrolyte separator, preparation method thereof and electrochemical device - Google Patents
Solid electrolyte separator, preparation method thereof and electrochemical device Download PDFInfo
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- CN117832758A CN117832758A CN202211212472.4A CN202211212472A CN117832758A CN 117832758 A CN117832758 A CN 117832758A CN 202211212472 A CN202211212472 A CN 202211212472A CN 117832758 A CN117832758 A CN 117832758A
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- solid electrolyte
- coating layer
- lithium
- base film
- polyethylene
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- 239000007784 solid electrolyte Substances 0.000 title claims abstract description 61
- 238000002360 preparation method Methods 0.000 title abstract description 14
- 239000011247 coating layer Substances 0.000 claims abstract description 59
- -1 polyethylene Polymers 0.000 claims abstract description 49
- 239000004698 Polyethylene Substances 0.000 claims abstract description 33
- 229920000573 polyethylene Polymers 0.000 claims abstract description 33
- 239000012528 membrane Substances 0.000 claims abstract description 27
- 239000011230 binding agent Substances 0.000 claims abstract description 19
- 239000002562 thickening agent Substances 0.000 claims abstract description 18
- 239000000080 wetting agent Substances 0.000 claims abstract description 14
- 239000000203 mixture Substances 0.000 claims description 21
- 239000003792 electrolyte Substances 0.000 claims description 17
- 239000002002 slurry Substances 0.000 claims description 14
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 11
- 229920001577 copolymer Polymers 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 10
- 239000002033 PVDF binder Substances 0.000 claims description 9
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 9
- 239000002904 solvent Substances 0.000 claims description 9
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 7
- 150000002500 ions Chemical class 0.000 claims description 7
- 229910052744 lithium Inorganic materials 0.000 claims description 7
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 7
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 7
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 6
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 6
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 6
- 239000000839 emulsion Substances 0.000 claims description 6
- YYVXOEQBDYYRKU-UHFFFAOYSA-K lithium;zinc;phosphate Chemical compound [Li+].[Zn+2].[O-]P([O-])([O-])=O YYVXOEQBDYYRKU-UHFFFAOYSA-K 0.000 claims description 6
- 238000002844 melting Methods 0.000 claims description 6
- 230000008018 melting Effects 0.000 claims description 6
- 239000004743 Polypropylene Substances 0.000 claims description 5
- 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 claims description 5
- VVSMKOFFCAJOSC-UHFFFAOYSA-L disodium;dodecylbenzene;sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O.CCCCCCCCCCCCC1=CC=CC=C1 VVSMKOFFCAJOSC-UHFFFAOYSA-L 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 229920001155 polypropylene Polymers 0.000 claims description 5
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 4
- NRJJZXGPUXHHTC-UHFFFAOYSA-N [Li+].[O--].[O--].[O--].[O--].[Zr+4].[La+3] Chemical compound [Li+].[O--].[O--].[O--].[O--].[Zr+4].[La+3] NRJJZXGPUXHHTC-UHFFFAOYSA-N 0.000 claims description 4
- NPDXHCPLBBTVKX-UHFFFAOYSA-K [Zr+4].P(=O)([O-])([O-])[O-].[Li+] Chemical compound [Zr+4].P(=O)([O-])([O-])[O-].[Li+] NPDXHCPLBBTVKX-UHFFFAOYSA-K 0.000 claims description 4
- CEMTZIYRXLSOGI-UHFFFAOYSA-N lithium lanthanum(3+) oxygen(2-) titanium(4+) Chemical compound [Li+].[O--].[O--].[O--].[O--].[Ti+4].[La+3] CEMTZIYRXLSOGI-UHFFFAOYSA-N 0.000 claims description 4
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 4
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 4
- LFZYLAXEYRJERI-UHFFFAOYSA-N [Li].[Zr] Chemical compound [Li].[Zr] LFZYLAXEYRJERI-UHFFFAOYSA-N 0.000 claims description 3
- SZEFOBMPGYTUDO-UHFFFAOYSA-N [O-2].[Ta+5].[La+3].[Li+] Chemical compound [O-2].[Ta+5].[La+3].[Li+] SZEFOBMPGYTUDO-UHFFFAOYSA-N 0.000 claims description 3
- DGQGEJIVIMHONW-UHFFFAOYSA-N [O-2].[Ta+5].[Zr+4].[La+3].[Li+] Chemical compound [O-2].[Ta+5].[Zr+4].[La+3].[Li+] DGQGEJIVIMHONW-UHFFFAOYSA-N 0.000 claims description 3
- UQSQSQZYBQSBJZ-UHFFFAOYSA-N fluorosulfonic acid Chemical compound OS(F)(=O)=O UQSQSQZYBQSBJZ-UHFFFAOYSA-N 0.000 claims description 3
- OVVKJDODGQRIDN-UHFFFAOYSA-N lithium lanthanum(3+) niobium(5+) oxygen(2-) Chemical compound [O-2].[Nb+5].[La+3].[Li+] OVVKJDODGQRIDN-UHFFFAOYSA-N 0.000 claims description 3
- 229920005862 polyol Polymers 0.000 claims description 3
- 150000003077 polyols Chemical class 0.000 claims description 3
- 239000006255 coating slurry Substances 0.000 claims description 2
- 125000005456 glyceride group Chemical group 0.000 claims description 2
- 229910052912 lithium silicate Inorganic materials 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 abstract description 15
- 239000011148 porous material Substances 0.000 abstract description 6
- 239000002585 base Substances 0.000 description 30
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 23
- 229910001416 lithium ion Inorganic materials 0.000 description 23
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 12
- 239000007774 positive electrode material Substances 0.000 description 12
- 229910052799 carbon Inorganic materials 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- 239000010410 layer Substances 0.000 description 10
- 229910052782 aluminium Inorganic materials 0.000 description 8
- 239000006258 conductive agent Substances 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 239000006183 anode active material Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 230000006872 improvement Effects 0.000 description 6
- 229910000664 lithium aluminum titanium phosphates (LATP) Inorganic materials 0.000 description 6
- 239000007773 negative electrode material Substances 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 5
- 238000002474 experimental method Methods 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- 239000000654 additive Substances 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 229910021383 artificial graphite Inorganic materials 0.000 description 4
- 229910001593 boehmite Inorganic materials 0.000 description 4
- 239000003575 carbonaceous material Substances 0.000 description 4
- 239000011883 electrode binding agent Substances 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 229910021382 natural graphite Inorganic materials 0.000 description 4
- 229920000049 Carbon (fiber) Polymers 0.000 description 3
- 239000006245 Carbon black Super-P Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000004917 carbon fiber Substances 0.000 description 3
- 239000011889 copper foil Substances 0.000 description 3
- 239000000835 fiber Substances 0.000 description 3
- 239000011302 mesophase pitch Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical group C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 2
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 description 2
- 229910015645 LiMn Inorganic materials 0.000 description 2
- 229910015643 LiMn 2 O 4 Inorganic materials 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 2
- 229920000265 Polyparaphenylene Polymers 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 150000001342 alkaline earth metals Chemical class 0.000 description 2
- 229910003481 amorphous carbon Inorganic materials 0.000 description 2
- 239000006256 anode slurry Substances 0.000 description 2
- 239000005466 carboxylated polyvinylchloride Substances 0.000 description 2
- 229910052798 chalcogen Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229920001940 conductive polymer Polymers 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000009831 deintercalation Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 229920005994 diacetyl cellulose Polymers 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 230000005518 electrochemistry Effects 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 229910021385 hard carbon Inorganic materials 0.000 description 2
- 239000001863 hydroxypropyl cellulose Substances 0.000 description 2
- 235000010977 hydroxypropyl cellulose Nutrition 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 239000003273 ketjen black Substances 0.000 description 2
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229920001778 nylon Polymers 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920006254 polymer film Polymers 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 229920002635 polyurethane Polymers 0.000 description 2
- 239000004814 polyurethane Substances 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 2
- 229920000915 polyvinyl chloride Polymers 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- 229920002620 polyvinyl fluoride Polymers 0.000 description 2
- 229920000973 polyvinylchloride carboxylated Polymers 0.000 description 2
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 2
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 2
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 229910021384 soft carbon Inorganic materials 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- WDXYVJKNSMILOQ-UHFFFAOYSA-N 1,3,2-dioxathiolane 2-oxide Chemical compound O=S1OCCO1 WDXYVJKNSMILOQ-UHFFFAOYSA-N 0.000 description 1
- 102000004310 Ion Channels Human genes 0.000 description 1
- 229910000733 Li alloy Inorganic materials 0.000 description 1
- 229910013733 LiCo Inorganic materials 0.000 description 1
- 229910013275 LiMPO Inorganic materials 0.000 description 1
- 229910014689 LiMnO Inorganic materials 0.000 description 1
- 229910013716 LiNi Inorganic materials 0.000 description 1
- 229910013705 LiNi 1-x Mn Inorganic materials 0.000 description 1
- 229910013292 LiNiO Inorganic materials 0.000 description 1
- 229910020813 Sn-C Inorganic materials 0.000 description 1
- 229910018732 Sn—C Inorganic materials 0.000 description 1
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000011884 anode binding agent Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- NKCVNYJQLIWBHK-UHFFFAOYSA-N carbonodiperoxoic acid Chemical compound OOC(=O)OO NKCVNYJQLIWBHK-UHFFFAOYSA-N 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000011294 coal tar pitch Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 239000011326 fired coke Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000011325 microbead Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000009828 non-uniform distribution Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229910052699 polonium Inorganic materials 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000002296 pyrolytic carbon Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 150000003346 selenoethers Chemical class 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
Classifications
-
- 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
Abstract
The invention relates to a solid electrolyte membrane, a preparation method thereof and an electrochemical device. The solid electrolyte separator includes a base film, and a coating layer formed on at least one side of the base film, the coating layer including the following components in mass fraction: 40-80% of solid electrolyte, 20-60% of polyethylene, 0-5% of binder, 0-1.5% of thickener and 0-1% of wetting agent. The solid electrolyte membrane is provided with the coating layer on at least one side of the base membrane, the solid electrolyte of the coating layer can effectively improve interface stability, the temperature of the closed pores of the membrane is obviously reduced by the polyethylene ball, and the impedance and the heating safety performance of the battery core can be reduced.
Description
Technical Field
The invention relates to the technical field of electrochemistry, in particular to a solid electrolyte membrane, a preparation method thereof and an electrochemistry device.
Background
The lithium ion battery has the characteristics of higher energy density, long service life, high power and the like, and is rapidly developed in the fields of energy storage and power. Currently, the power field has increasingly high requirements on the energy density, the safety performance and the calendar life of lithium ion batteries. The current strategy mainly adopts a high-voltage monocrystal positive electrode material to simultaneously consider the energy density and the safety performance of the battery cell, however, the mode can bring deterioration of dynamic performance, and the improvement on long-term high-temperature storage, long service life and battery cell safety is very limited.
The energy density improvement strategy for improving the variable valence element content of the positive electrode and improving the use condition of the positive electrode is the mainstream at present, but the strategy has obvious deterioration on the cycle life, the safety performance and the high-temperature storage performance of the battery. The method mainly comprises the steps of improving the shape of positive electrode particles, increasing doping and cladding amount of the positive electrode, optimizing sintering curves and the like around the positive electrode and electrolyte in the early stage, wherein the monocrystalline material is used for improving the high-temperature gas production of the battery cell to a certain extent, but the safety performance and the service life of the battery cell are not obviously improved, and meanwhile, the cost is obviously increased; the direction of the electrolyte is mainly to introduce some high-efficiency interfacial film-forming additives such as methyl disulfonate, ethylene sulfite and the like, however, the introduction of the additives in the electrolyte can influence the conductivity of the electrolyte, increase the interfacial impedance, and deteriorate the low-temperature performance, high-rate discharge, cycle life and other electrical properties.
Disclosure of Invention
Based on this, it is necessary to provide a solid electrolyte separator, a method for preparing the same, and an electrochemical device to reduce the resistance and improve the safety of heating the battery cells.
A solid electrolyte separator comprising a base film and a coating layer formed on at least one side of the base film, the coating layer comprising the following components in mass fraction:
in one embodiment, the polyethylene has a melting point of 90℃to 130 ℃.
In one embodiment, the coating layer is distributed in a dot shape on the base film, and the coating layer covers 50% -90% of the area of the base film.
In one embodiment, the solid electrolyte has a D50 particle size of no more than 4.5 μm and is ionic at room temperatureConductivity is not lower than 1×10 -3 ms/cm。
In one embodiment, the solid electrolyte separator meets at least one of the following characteristics:
(1) The thickness of the base film is 1-50 mu m;
(2) The thickness of the coating layer is 0.1-10 mu m.
In one embodiment, the solid electrolyte separator meets at least one of the following characteristics:
(1) The material of the base film is at least one selected from polyethylene, ethylene-propylene copolymer, polypropylene, ethylene-butene copolymer, ethylene-hexene copolymer and ethylene-methacrylate copolymer;
(2) The material of the solid electrolyte is at least one selected from zirconium lithium silicate, zinc lithium phosphate, titanium aluminum lithium phosphate, lithium lanthanum zirconium tantalum oxide, lithium lanthanum zirconium oxide, lithium lanthanum niobium oxide, lithium lanthanum tantalum oxide, lithium lanthanum titanium oxide, lithium calcium tantalum oxide, zirconium lithium phosphate and zinc lithium phosphate.
In one embodiment, the solid electrolyte separator meets at least one of the following characteristics:
(1) The thickener is at least one selected from sodium carboxymethyl cellulose and lithium carboxymethyl cellulose;
(2) The binder is at least one selected from polyvinylidene fluoride and polymethyl methacrylate;
(3) The wetting agent is at least one selected from sodium dodecyl benzene sulfate, fatty glyceride, perfluorosulfonate and modified polyol.
A method of preparing a solid electrolyte separator comprising the steps of:
obtaining a base film, coating slurry on at least one side of the base film, and drying the slurry to form a coating layer, wherein the coating layer comprises the following components in percentage by mass:
in one embodiment, the slurry is prepared by the following method:
dissolving a thickening agent and a binder in a solvent to obtain a first mixture;
adding polyethylene emulsion into the first mixture to obtain a second mixture;
and adding a solid electrolyte and a wetting agent into the second mixture to obtain the slurry.
An electrochemical device having the solid electrolyte membrane of any one of the above embodiments or a solid electrolyte membrane prepared by the preparation method of any one of the above embodiments.
Compared with the prior art, the solid electrolyte membrane, the preparation method thereof and the electrochemical device have the following beneficial effects:
according to the solid electrolyte membrane and the preparation method thereof, the coating layer is formed on at least one side of the base membrane, the solid electrolyte of the coating layer can effectively improve interface stability, the temperature of the closed pores of the membrane is obviously reduced by the polyethylene ball, the impedance can be reduced, and the heating safety performance of the battery core can be improved.
The solid electrolyte membrane has excellent electrochemical calendar stability and thermodynamic calendar stability, has higher migration number of lithium ions, can obviously reduce the electrolyte injection amount, improves the energy density, and improves the cycle life and the high-temperature storage performance. In the formation process, the solid electrolyte interface and the pole piece form an intermediate phase, and the intermediate phase has excellent mechanical strength and toughness, and meanwhile, the ion conductivity is not affected, so that the mechanical safety performance of the battery cell is remarkably improved.
The above electrochemical device contains the above solid electrolyte separator, and thus can obtain corresponding technical effects.
Detailed Description
The present invention will be described more fully hereinafter in order to facilitate an understanding of the present invention. This invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The invention provides a solid electrolyte membrane which can be applied to a lithium ion battery.
The solid electrolyte membrane of an embodiment includes a base film and a coating layer formed on the base film. Wherein the coating layer comprises the following components in percentage by mass:
the solid electrolyte membrane comprises the base membrane and the coating layer formed on the base membrane, wherein the solid electrolyte of the coating layer can effectively improve interface stability, the temperature of the closed pores of the membrane is obviously reduced by the polyethylene ball, impedance can be reduced, and the heating safety performance of the battery core can be improved.
The solid electrolyte membrane has excellent electrochemical calendar stability and thermodynamic calendar stability, has higher migration number of lithium ions, can obviously reduce the electrolyte injection amount, improves the energy density, and improves the cycle life and the high-temperature storage performance. In the formation process, the solid electrolyte interface and the pole piece form an intermediate phase, and the intermediate phase has excellent mechanical strength and toughness, and meanwhile, the ion conductivity is not affected, so that the mechanical safety performance of the battery cell is remarkably improved.
Alternatively, the base film may have a single-layer structure or a multilayer structure.
Alternatively, the material of the base film may be at least one selected from, but not limited to, polyethylene, ethylene-propylene copolymer, polypropylene, ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-methacrylate copolymer.
In one example, the base film has a thickness of 1 to 50 μm. Further, in one example, the thickness of the base film is 4 to 20 μm. In some specific examples, the thickness of the base film is 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, etc.
In one example, the base film is a porous film. Further, the porosity of the base film is 20% -60%, preferably 30% -40%, and the pore diameter is above 100 nm.
The rupture temperature of the base film is not lower than 150 ℃, and the self-closing hole temperature is not higher than 145 ℃. The MD directional elongation of the base film is not lower than 120%, and the TD directional elongation is not higher than 120%. The pore D50 of the base film is distributed between 10 and 90 mu m.
Alternatively, the coating layer may be formed on only one side of the base film, or may be formed on both sides of the base film.
In one example, the coating layer is distributed in a dot shape on the base film. Further, the coating layer is dotted and uniformly distributed on the base film. In other examples, the coating layer may also be in a dot-like, non-uniform distribution.
In one example, the coating layer covers 50% to 90% of the area of one side of the base film, i.e., the area of the base film not covered by the coating layer occupies 10% to 50% of the total area.
In one example, the thickness of the coating layer is 30% to 50% of the thickness of the base film.
In one example, the thickness of the coating layer is 0.1 to 10 μm, specifically, for example, 0.5 μm, 1 μm, 2 μm, 5 μm, 8 μm, or the like.
In the coating layer, the mass fraction of the solid electrolyte is 40% -80%. Solid electrolytes can be effective in improving interfacial stability, but too high a content may result in a decrease in stability of the coating layer slurry.
Optionally, the material of the solid electrolyte is selected from at least one of lithium zirconium silicate, lithium zinc phosphate, lithium aluminum titanium phosphate, lithium lanthanum zirconium tantalum oxide, lithium lanthanum zirconium oxide, lithium lanthanum niobium oxide, lithium lanthanum tantalum oxide, lithium lanthanum titanium oxide, lithium calcium tantalum oxide, lithium zirconium phosphate, and lithium zinc phosphate.
In one example, the D50 particle size of the solid electrolyte is not higher than 4.5 μm, for example, 500nm to 4.5 μm, and the ion conductivity at room temperature is not lower than 1X 10 -3 ms/cm。
The mass fraction of the polyethylene is 20% -60%. Too high a polyethylene content can seriously affect the viscosity and leveling properties of the coating layer slurry and affect the processability of the slurry.
The polyethylene preferably has a lower melting point. In one example, the polyethylene has a melting point of 90℃to 130 ℃. Further, in one example, the polyethylene has a melting point of 90 ℃ to 108 ℃. In some specific examples, the polyethylene has a melting point of 90 ℃, 95 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, and the like. The low-melting-point polyethylene is selected, so that the closed pore temperature of the diaphragm can be reduced better.
The mass fraction of the binder is 0-5%. Further, in one example, the mass fraction of binder is 0.25% to 5%.
Alternatively, the binder may be at least one of, but not limited to, polyvinylidene fluoride and polymethyl methacrylate.
The mass fraction of the thickener is 0-1.5%. Further, in one example, the mass fraction of thickener is 0.5% to 1.5%.
Alternatively, the thickener may be at least one of, but not limited to, sodium carboxymethyl cellulose and lithium carboxymethyl cellulose.
The mass fraction of the wetting agent is 0-1%. Further, in one example, the wetting agent is present in an amount of 0.75% to 1% by mass.
Optionally, the wetting agent is selected from at least one of sodium dodecyl benzene sulfate, fatty acid glyceride, perfluorosulfonate, and modified polyol.
Further, the invention also provides a preparation method of the solid electrolyte membrane of any example.
The preparation method of the solid electrolyte membrane in one embodiment comprises the following steps:
a base film is obtained, slurry is coated on the base film and dried, so that the slurry forms a coating layer, and the coating layer comprises the following components in percentage by mass:
in one example, the slurry is prepared by the following method:
and S1, dissolving a thickening agent and a binder in a solvent to obtain a first mixture.
And S2, adding polyethylene emulsion into the first mixture to obtain a second mixture.
And step S3, adding solid electrolyte and wetting agent into the second mixture to obtain the slurry.
Wherein, the polyethylene component is added in the form of polyethylene emulsion to form polyethylene spherical particles, which is convenient for uniform mixing with other materials.
In one example, the solids content of the polyethylene emulsion may be 10% to 50%, specifically, for example, 10%, 20%, 30%, 40%, 50%, etc.
Further, the invention also provides an electrochemical device.
An electrochemical device of an embodiment includes a housing, a positive electrode sheet, a negative electrode sheet, an electrolyte, and a solid electrolyte separator of any of the examples described above disposed in the housing.
The electrochemical device may be a lithium ion battery, a sodium ion battery, a zinc ion battery, a supercapacitor, or the like.
Hereinafter, an electrochemical device will be described in more detail by taking a lithium ion battery as an example, but the present invention is not limited thereto.
In a lithium ion battery, a positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material, and may further contain a binder, a conductive agent, and the like.
The positive electrode current collector is a supporting layer capable of conducting electricity and not reacting with other components in the electrochemical device, for example, aluminum foil may be selected as the positive electrode current collector.
The positive electrode active material is selected from substances capable of desorbing lithium ions. For example, the positive electrode active material may be selected from LiMnO 2 、LiMn 2 O 4 LiNi 1-x Co y O 2 、LiCo 1-x Mn x O 2 、LiNi 1-x Mn x O 2 (0＜x＜1)、Li(Ni x Co y Mn z )O 4 (0＜x＜1，0＜y＜1，0＜z＜1，0＜x+y+z＜1)、LiMn 2-a Ni a O 4 、LiMn 2-a Co a O 4 (0＜a＜2)、LiMPO 4 (M is one or more selected from Co, ni, fe, mn and V), spinel material LiMn 2 O 4 Layered material lithium cobalt oxide (LiCoO) 2 ) Lithium nickelate (LiNiO) 2 )、Li a Ni x A y B (1-x-y) O 2 (0.95.ltoreq.a.ltoreq.1, A and B may be independently selected from one of Co, mn and Al, and A and B are different, 0 < x < 1,0 < y < 1,0 < x+y < 1), etc. The positive electrode active material may include at least one of sulfide, selenide, and halide.
In one example, the surface of the positive electrode active material also has a coating layer, or is mixed with a material having a coating layer. In one example, the coating layer includes at least one selected from an oxide, hydroxide, oxyhydroxide, oxycarbonate, and hydroxycarbonate of the coating element. The coating element comprises a mixture of one or more of Mg, al, co, K, na, ca, si, ti, V, sn, ge, ga, B, as, zr. The compound forming the coating layer may be crystalline or amorphous.
In one example, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent. The positive electrode binder is used to improve the binding properties of the positive electrode active material particles to each other and to the current collector. The positive electrode binder is, for example, at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethyleneoxy-containing polymer, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber of acrylic acid (ester), epoxy resin, and nylon. The positive electrode conductive agent is used to provide conductivity to the electrode, and may include any conductive material as long as it does not chemically react with the positive electrode active material. The positive electrode conductive agent is, for example, at least one of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, and polyphenylene derivative. Wherein the metal in the metal powder and the metal fiber comprises at least one of copper, nickel, aluminum and silver.
The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The anode active material layer contains an anode active material.
In some embodiments, the negative electrode current collector is a supporting layer that is capable of conducting electricity and that does not react with other components in the electrochemical device, for example, a copper foil may be used as the negative electrode current collector.
The negative electrode active material is a substance capable of reversibly intercalating and deintercalating active ions, or a substance capable of reversibly doping and deintercalating active ions. In one example, the negative electrode active material includes at least one of lithium metal, a lithium metal alloy, a carbon material, and a silicon-based material. The lithium metal alloy comprises an alloy of lithium and a metal selected from Na, K, rb, cs, fr, be, mg, ca, sr, si, sb, in, zn, ba, ra, ge, al, sn. In one example, the carbon material is selected from at least one of crystalline carbon and amorphous carbon. The crystalline carbon is, for example, natural graphite or artificial graphite. The crystalline carbon is amorphous, plate-shaped, sheet-shaped, spherical or fibrous in shape. In one example, the crystalline carbon is a low crystalline carbon or a high crystalline carbon. The low crystalline carbon includes at least one of soft carbon and hard carbon. The high crystalline carbon comprises at least one of natural graphite, crystalline graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesophase carbon microbeads, mesophase pitch, and high temperature calcined carbon. The high temperature calcined carbon is petroleum or coke derived from coal tar pitch. The amorphous carbon is soft carbon,At least one of hard carbon, mesophase pitch carbonized product, and fired coke. In one example, the anode active material includes a transition metal oxide. In one example, the anode active material includes Si, siO x (0 < x < 2), si/C composite, si-Q alloy, sn, snO Z At least one of a Sn-C compound and a Sn-R alloy. Wherein Q is at least one selected from alkali metal, alkaline earth metal, group 13 to group 16 elements, transition element and rare earth element, and Q is not Si. R is at least one selected from alkali metal, alkaline earth metal, group 13 to group 16 elements, transition element and rare earth element, and R is not Sn. Wherein Q and R comprise at least one of Mg, ca, sr, ba, sc, Y, ti, zr, hf, rf, V, nb, ta, db, cr, mo, W, sg, tc, re, bh, fe, pb, ru, os, hs, rh, ir, pd, pt, cu, ag, au, zn, cd, B, al, ga, sn, in, tl, ge, P, as, sb, bi, S, se, te and Po.
In one example, the anode active material layer further includes an anode binder and an anode conductive agent. The negative electrode binder is, for example, at least one of vinylidene fluoride-hexafluoropropylene copolymer (PVDF-Co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethyleneoxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber of acrylic acid (ester), epoxy resin, and nylon. The negative electrode conductive agent is used to provide conductivity to the electrode, and is, for example, one or more of a carbon-based material, a metal-based material, and a conductive polymer. Wherein the carbon-based material is at least one of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber, for example. The metal-based material is, for example, at least one of metal powder of copper, nickel, aluminum, silver, etc., and metal fiber. The conductive polymer is, for example, a polyphenylene derivative.
In the preparation process of the anode slurry, a solvent is generally added, an anode active material is added with a binder, and a conductive material and a thickener are added as needed, and then dissolved or dispersed in the solvent to prepare the anode slurry. The solvent is volatilized during the drying process. The solvent is, for example, water and the thickener is, for example, sodium carboxymethylcellulose.
The mixing ratio of the negative electrode active material, the binder, and the thickener in the negative electrode active material layer is not particularly limited, and the content may be optimized according to the performance expectation.
The equipment using the above electrochemical device may be, for example, but not limited to, an automobile, a motorcycle, a skateboard, an airplane, a passenger car, a motor, a standby power supply, a large-sized storage battery for home use, a lithium ion capacitor, a computer, a cellular phone, an electronic book, a facsimile machine, a copier, a flash lamp, a television, a VR/AR, an energy storage power station, a marine vehicle, an air vehicle, and the like. Wherein the air vehicle comprises an air vehicle within the atmosphere and an air vehicle outside the atmosphere.
The invention will be further illustrated with reference to specific examples.
Examples 1 to 10
The solid electrolyte separators provided in examples 1 to 10 were prepared by using a porous polyethylene polymer film as a base film, and forming coating layers on both sides of the base film, respectively. The coating layer is composed of solid electrolyte, polyethylene, binder, thickener and wetting agent with the mass ratio of 75:21:2.5:1:0.5.
Wherein the thickener is sodium carboxymethyl cellulose, the binder is polyvinylidene fluoride, and the wetting agent is sodium dodecyl benzene sulfate.
In examples 1 to 4, the solid electrolyte was Lithium Aluminum Titanium Phosphate (LATP). In examples 5 to 6, the solid electrolyte was Lithium Lanthanum Zirconium Oxide (LLZO). In examples 7 to 8, the solid electrolyte was Lithium Lanthanum Titanium Oxide (LLTO). In examples 9 to 10, the solid electrolyte was Lithium Zirconium Phosphate (LZP).
The preparation method of the solid electrolyte membrane comprises the following steps:
dissolving a thickening agent and a binder in water to obtain a first mixture;
adding polyethylene emulsion into the first mixture to obtain a second mixture;
and adding a solid electrolyte and a wetting agent into the second mixture to obtain the slurry.
Comparative examples 1 to 10
The separators of comparative examples 1 to 10 were made of porous polyethylene polymer films as the base films. In comparative example 1, no coating layer was formed. Comparative examples 2 to 10 each formed a coating layer on both sides of the base film. In comparative examples 2 to 4, the coating layer component was polyethylene. In comparative examples 5 to 7, the coating layer was composed of boehmite, polyethylene, a binder, a thickener and a wetting agent in a mass ratio of 75:21:2.5:1:0.5. Wherein the thickener is sodium carboxymethyl cellulose, the binder is polyvinylidene fluoride, and the wetting agent is sodium dodecyl benzene sulfate. In comparative examples 8 to 10, the coating layer component was Lithium Aluminum Titanium Phosphate (LATP).
The separators using the above examples 1 to 10 and comparative examples 1 to 10 were applied to lithium ion batteries of the same structure, and the lithium ion batteries were prepared as follows.
Preparation of a positive plate:
the environment is required to have humidity lower than 10% and temperature 20-30 ℃.
Preparing super-P conductive solution with 65% of solid content, and uniformly coating the solution on the surface of the aluminum foil to obtain the aluminum foil with the conductive coating. Forming a positive electrode active material layer on the aluminum foil, wherein the formula is as follows: li (Ni) 0.8 Co 0.1 Mn 0.1 )O 2 The mass ratio of the conductive agent Super-P to the binder polyvinylidene fluoride is 96:2.2:1.8. And rolling, slitting and cutting to obtain the positive plate. The coating surface density of the positive plate is 14.0mg/cm 2 Compacting 3.3g/cm 3 。
Preparing a negative plate:
mixing negative electrode active material artificial graphite, conductive agent Super-P, thickener sodium carboxymethylcellulose (CMC) and binder styrene-butadiene rubber according to the mass ratio of 96.2:2:0.8:1, adding deionized water, and obtaining negative electrode slurry with the solid content of 54wt% under the action of a vacuum stirrer.
And uniformly coating the negative electrode slurry on a negative electrode current collector copper foil. And (3) drying the coated copper foil at a high temperature, cold pressing, cutting, slitting and drying for 12 hours under the vacuum condition at 120 ℃ to obtain the negative plate.
Preparation of electrolyte:
in a dry argon glove box, solvents (including EC, DEC, EMC, mass ratio 3:2:5), additives and lithium salts were mixed in the desired amounts. Specifically, a solvent is added firstly, then an additive is added, lithium salt is added after dissolution and full stirring, and the electrolyte is obtained after uniform mixing.
Preparation of a lithium ion battery:
and stacking the positive plate, the diaphragm and the negative plate in sequence, enabling the diaphragm to be positioned between the positive plate and the negative plate, playing an isolating role, and then winding to obtain the bare cell. After welding the electrode lugs, placing the obtained bare cell in an aluminum plastic film of an outer package, injecting the prepared electrolyte into the dried bare cell, vacuum packaging, standing, forming (charging 3.3V with a constant current of 0.02C and then charging 3.6V with a constant current of 0.1C), shaping, testing the capacity and other procedures to obtain the target cell.
The lithium ion batteries using the separators of examples 1 to 10 and comparative examples 1 to 10 described above were subjected to performance tests including DCR test and heat test, and the test methods are specifically as follows.
Lithium ion battery DCR test:
placing the lithium ion battery in a constant temperature box at 25 ℃ for 2 hours, charging to 4.2V with constant current of 0.5C, charging to 0.05C with constant voltage, standing for 5min, discharging to 3.0V with constant current of 0.1C, and recording as capacity C 2 . At 0.2C 2 Constant current discharge for 2.5h, recording end voltage U 0 ，1C 2 Discharge for 1s, record terminal voltage U 1 。
The calculation formula of the DC internal resistance DCR is as follows: dcr= (U 0 -U 1 )/(0.9C 2 )。
Lithium ion heating test:
each verification group takes 5 electric cores, the lithium ion battery is charged to 3.65V at a constant current of 0.5C, and then the thickness of the lithium ion battery is measured by using a plate thickness gauge to obtain L1. Continuously charging the lithium ion battery to 4.2V at a constant current of 0.5C, charging the lithium ion battery to 0.05C at a constant voltage, then placing the lithium ion battery in a high-temperature oven, setting the high-temperature oven to 180 ℃, keeping the temperature for 1h after the temperature rises to the target temperature, and heating the lithium ion battery at a speed of 5 ℃/min. The electric core is not ignited and does not explode, namely passes.
Table 1 results of DCR test and core heating test for different experimental groups
As can be seen from the DCR test results of comparative examples 1 to 7 above, the formation of an inorganic or organic coating layer with a relatively thin thickness (thickness of 1 μm or less) on the separator greatly contributes to the liquid retention at the separator/pole piece interface, however, when the thickness of the coating layer is greater than 1 μm, it causes a decrease in the air permeability of the separator itself, increasing ion obstruction, and deteriorating the impedance. From the test results of the above comparative examples 8 to 10, it is seen that when the coating layer composition is a solid electrolyte, the solid electrolyte has both the effects of increasing the retention and constructing the dual ion channels, thereby significantly improving the impedance. However, when the thickness of the coating layer is too large, for example, when the thickness is 5 μm or more, the air permeability of the separator is deteriorated, and the improvement effect is also affected.
From the test results of examples 1 to 10 above, it was found that the impedance can be significantly improved when the coating layer composition includes a solid electrolyte and polyethylene. When the thickness of the single-sided coating layer is 1.5 mu m, the improvement effect on the cell DCR is most remarkable. Of these, the cell DCR of example 2 was the lowest.
From the results of the electric core heating experiments of the comparative examples 1 to 4, it is apparent that the electric core heating experiment performance is improved to a certain extent by introducing polyethylene with a certain thickness on the diaphragm, and the passing rate of the heating experiment is improved obviously when the thickness of the coating layer reaches 1 mu m, and the improvement effect is not increased obviously by continuously increasing the thickness of the coating layer. The existence of polyethylene can enable the cell diaphragm to realize high-temperature self-closing hole, and inhibit Joule heat in the cell, but can not inhibit stress heat shrinkage of the diaphragm. And further introducing boehmite, the improvement amplitude can be further improved because boehmite can inhibit the stress thermal shrinkage of the separator. The safety performance of the battery core heating is obviously improved when the coating layer is a solid electrolyte, and the main reason is that the battery core heating has higher heat capacity effect and rigid self-support and inhibits interface reaction heat generation and diaphragm shrinkage.
The test results of examples 1 to 10 show that when the coating layer composition comprises the solid electrolyte and the polyethylene, the passing proportion of the heating experiment can be remarkably improved, and compared with the introduction of boehmite, the resistance and the heating safety performance of the battery cell can be better improved. In particular, when the coating layer is a mixture of polyethylene and LATP and the thickness of one side is 1.5-3 μm, the passing rate of the cell reaches 100% in a 180 ℃ heating experiment.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. 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 invention, which are all within the scope of the invention. The scope of the invention is, therefore, indicated by the appended claims, and the description may be intended to interpret the contents of the claims.
Claims (10)
1. A solid electrolyte separator characterized by comprising a base film and a coating layer formed on at least one side of the base film, the coating layer comprising the following components in mass fraction:
2. the solid state electrolyte separator of claim 1 wherein the polyethylene has a melting point of 90 ℃ to 130 ℃.
3. The solid electrolyte membrane of claim 1, wherein the coating layer is punctuated on the base film, the coating layer covering 50% to 90% of the area of the base film.
4. The solid electrolyte membrane according to claim 1, wherein the solid electrolyte has a D50 particle size of not more than 4.5 μm and an ion conductivity of not less than 1 x 10 at room temperature -3 ms/cm。
5. The solid state electrolyte separator of any one of claims 1-4, wherein the solid state electrolyte separator meets at least one of the following characteristics:
(1) The thickness of the base film is 1-50 mu m;
(2) The thickness of the coating layer is 0.1-10 mu m.
6. The solid state electrolyte separator of any one of claims 1-4, wherein the solid state electrolyte separator meets at least one of the following characteristics:
(1) The material of the base film is at least one selected from polyethylene, ethylene-propylene copolymer, polypropylene, ethylene-butene copolymer, ethylene-hexene copolymer and ethylene-methacrylate copolymer;
(2) The material of the solid electrolyte is at least one selected from zirconium lithium silicate, zinc lithium phosphate, titanium aluminum lithium phosphate, lithium lanthanum zirconium tantalum oxide, lithium lanthanum zirconium oxide, lithium lanthanum niobium oxide, lithium lanthanum tantalum oxide, lithium lanthanum titanium oxide, lithium calcium tantalum oxide, zirconium lithium phosphate and zinc lithium phosphate.
7. The solid state electrolyte separator of any one of claims 1-4, wherein the solid state electrolyte separator meets at least one of the following characteristics:
(1) The thickener is at least one selected from sodium carboxymethyl cellulose and lithium carboxymethyl cellulose;
(2) The binder is at least one selected from polyvinylidene fluoride and polymethyl methacrylate;
(3) The wetting agent is at least one selected from sodium dodecyl benzene sulfate, fatty glyceride, perfluorosulfonate and modified polyol.
8. A method for preparing a solid electrolyte membrane, comprising the steps of:
obtaining a base film, coating slurry on at least one side of the base film, and drying the slurry to form a coating layer, wherein the coating layer comprises the following components in percentage by mass:
9. the method of claim 8, wherein the slurry is prepared by:
dissolving a thickening agent and a binder in a solvent to obtain a first mixture;
adding polyethylene emulsion into the first mixture to obtain a second mixture;
and adding a solid electrolyte and a wetting agent into the second mixture to obtain the slurry.
10. An electrochemical device characterized by having the solid electrolyte membrane according to any one of claims 1 to 7 or the solid electrolyte membrane produced by the production method according to claim 8 or 9.
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