CN117525339A - Composite anode layer, preparation method and application thereof in battery - Google Patents
Composite anode layer, preparation method and application thereof in battery Download PDFInfo
- Publication number
- CN117525339A CN117525339A CN202311567962.0A CN202311567962A CN117525339A CN 117525339 A CN117525339 A CN 117525339A CN 202311567962 A CN202311567962 A CN 202311567962A CN 117525339 A CN117525339 A CN 117525339A
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- Prior art keywords
- transition metal
- carbon
- lithium
- fluoride
- source
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- 239000002131 composite material Substances 0.000 title claims abstract description 45
- 238000002360 preparation method Methods 0.000 title claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 110
- 239000000463 material Substances 0.000 claims abstract description 87
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 81
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 80
- 229910021524 transition metal nanoparticle Inorganic materials 0.000 claims abstract description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 48
- 229910052723 transition metal Inorganic materials 0.000 claims description 41
- 150000003624 transition metals Chemical class 0.000 claims description 33
- 229910052757 nitrogen Inorganic materials 0.000 claims description 25
- 229910052799 carbon Inorganic materials 0.000 claims description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- 229910052731 fluorine Inorganic materials 0.000 claims description 14
- -1 transition metal acetate Chemical class 0.000 claims description 14
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 13
- 239000011737 fluorine Substances 0.000 claims description 13
- 239000002253 acid Substances 0.000 claims description 12
- 238000001354 calcination Methods 0.000 claims description 12
- 229910052698 phosphorus Inorganic materials 0.000 claims description 11
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 10
- 239000011574 phosphorus Substances 0.000 claims description 10
- 239000002243 precursor Substances 0.000 claims description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 8
- 238000000576 coating method Methods 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 229910052755 nonmetal Inorganic materials 0.000 claims description 8
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 8
- 239000003153 chemical reaction reagent Substances 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 7
- 239000010949 copper Substances 0.000 claims description 7
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 6
- DTQVDTLACAAQTR-UHFFFAOYSA-N Trifluoroacetic acid Chemical compound OC(=O)C(F)(F)F DTQVDTLACAAQTR-UHFFFAOYSA-N 0.000 claims description 6
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 239000012039 electrophile Substances 0.000 claims description 5
- 239000002002 slurry Substances 0.000 claims description 5
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 claims description 4
- WTEOIRVLGSZEPR-UHFFFAOYSA-N boron trifluoride Chemical compound FB(F)F WTEOIRVLGSZEPR-UHFFFAOYSA-N 0.000 claims description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 4
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 claims description 4
- 235000013024 sodium fluoride Nutrition 0.000 claims description 4
- 239000011775 sodium fluoride Substances 0.000 claims description 4
- AKEJUJNQAAGONA-UHFFFAOYSA-N sulfur trioxide Chemical compound O=S(=O)=O AKEJUJNQAAGONA-UHFFFAOYSA-N 0.000 claims description 4
- FPGGTKZVZWFYPV-UHFFFAOYSA-M tetrabutylammonium fluoride Chemical compound [F-].CCCC[N+](CCCC)(CCCC)CCCC FPGGTKZVZWFYPV-UHFFFAOYSA-M 0.000 claims description 4
- RIOQSEWOXXDEQQ-UHFFFAOYSA-N triphenylphosphine Chemical compound C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 RIOQSEWOXXDEQQ-UHFFFAOYSA-N 0.000 claims description 4
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 claims description 4
- 239000002033 PVDF binder Substances 0.000 claims description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 3
- MIOPJNTWMNEORI-GMSGAONNSA-N (S)-camphorsulfonic acid Chemical compound C1C[C@@]2(CS(O)(=O)=O)C(=O)C[C@@H]1C2(C)C MIOPJNTWMNEORI-GMSGAONNSA-N 0.000 claims description 2
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 claims description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 2
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 claims description 2
- 229910015900 BF3 Inorganic materials 0.000 claims description 2
- 239000005711 Benzoic acid Substances 0.000 claims description 2
- 239000002028 Biomass Substances 0.000 claims description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 2
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 claims description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 claims description 2
- 239000012298 atmosphere Substances 0.000 claims description 2
- 235000010233 benzoic acid Nutrition 0.000 claims description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 2
- 229910017052 cobalt Inorganic materials 0.000 claims description 2
- 239000010941 cobalt Substances 0.000 claims description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 2
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 claims description 2
- 229910000397 disodium phosphate Inorganic materials 0.000 claims description 2
- 235000019800 disodium phosphate Nutrition 0.000 claims description 2
- ZRRLFMPOAYZELW-UHFFFAOYSA-N disodium;hydrogen phosphite Chemical compound [Na+].[Na+].OP([O-])[O-] ZRRLFMPOAYZELW-UHFFFAOYSA-N 0.000 claims description 2
- 235000019253 formic acid Nutrition 0.000 claims description 2
- 229910021389 graphene Inorganic materials 0.000 claims description 2
- 150000002357 guanidines Chemical class 0.000 claims description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 claims description 2
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 claims description 2
- 229910001635 magnesium fluoride Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 239000011572 manganese Substances 0.000 claims description 2
- GICWIDZXWJGTCI-UHFFFAOYSA-I molybdenum pentachloride Chemical compound Cl[Mo](Cl)(Cl)(Cl)Cl GICWIDZXWJGTCI-UHFFFAOYSA-I 0.000 claims description 2
- 229910000403 monosodium phosphate Inorganic materials 0.000 claims description 2
- 235000019799 monosodium phosphate Nutrition 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 235000006408 oxalic acid Nutrition 0.000 claims description 2
- 235000014786 phosphorus Nutrition 0.000 claims description 2
- 235000003270 potassium fluoride Nutrition 0.000 claims description 2
- 239000011698 potassium fluoride Substances 0.000 claims description 2
- 230000035484 reaction time Effects 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 claims description 2
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 2
- 239000001488 sodium phosphate Substances 0.000 claims description 2
- 229910000162 sodium phosphate Inorganic materials 0.000 claims description 2
- 235000011008 sodium phosphates Nutrition 0.000 claims description 2
- BRKFQVAOMSWFDU-UHFFFAOYSA-M tetraphenylphosphanium;bromide Chemical compound [Br-].C1=CC=CC=C1[P+](C=1C=CC=CC=1)(C=1C=CC=CC=1)C1=CC=CC=C1 BRKFQVAOMSWFDU-UHFFFAOYSA-M 0.000 claims description 2
- HPGGPRDJHPYFRM-UHFFFAOYSA-J tin(iv) chloride Chemical compound Cl[Sn](Cl)(Cl)Cl HPGGPRDJHPYFRM-UHFFFAOYSA-J 0.000 claims description 2
- UBZYKBZMAMTNKW-UHFFFAOYSA-J titanium tetrabromide Chemical compound Br[Ti](Br)(Br)Br UBZYKBZMAMTNKW-UHFFFAOYSA-J 0.000 claims description 2
- 229910021381 transition metal chloride Inorganic materials 0.000 claims description 2
- 229910021561 transition metal fluoride Inorganic materials 0.000 claims description 2
- 229910002001 transition metal nitrate Inorganic materials 0.000 claims description 2
- FEONEKOZSGPOFN-UHFFFAOYSA-K tribromoiron Chemical compound Br[Fe](Br)Br FEONEKOZSGPOFN-UHFFFAOYSA-K 0.000 claims description 2
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 2
- NCPXQVVMIXIKTN-UHFFFAOYSA-N trisodium;phosphite Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])[O-] NCPXQVVMIXIKTN-UHFFFAOYSA-N 0.000 claims description 2
- 235000005074 zinc chloride Nutrition 0.000 claims description 2
- 239000011592 zinc chloride Substances 0.000 claims description 2
- 229910021627 Tin(IV) chloride Inorganic materials 0.000 claims 1
- 229910017053 inorganic salt Inorganic materials 0.000 claims 1
- 229910052744 lithium Inorganic materials 0.000 abstract description 55
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 52
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 24
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 24
- 230000005540 biological transmission Effects 0.000 abstract description 19
- 210000001787 dendrite Anatomy 0.000 abstract description 18
- 230000000149 penetrating effect Effects 0.000 abstract description 7
- 239000002071 nanotube Substances 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 18
- 230000015572 biosynthetic process Effects 0.000 description 13
- 239000000243 solution Substances 0.000 description 10
- 238000005452 bending Methods 0.000 description 7
- 230000009286 beneficial effect Effects 0.000 description 7
- 230000007547 defect Effects 0.000 description 7
- 239000012634 fragment Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 238000009831 deintercalation Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 239000002210 silicon-based material Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 230000001788 irregular Effects 0.000 description 3
- 230000002427 irreversible effect Effects 0.000 description 3
- 230000006911 nucleation Effects 0.000 description 3
- 238000010899 nucleation Methods 0.000 description 3
- 229920001296 polysiloxane Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229920002125 Sokalan® Polymers 0.000 description 2
- 239000002174 Styrene-butadiene Substances 0.000 description 2
- CKUAXEQHGKSLHN-UHFFFAOYSA-N [C].[N] Chemical group [C].[N] CKUAXEQHGKSLHN-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- SZQUEWJRBJDHSM-UHFFFAOYSA-N iron(3+);trinitrate;nonahydrate Chemical compound O.O.O.O.O.O.O.O.O.[Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O SZQUEWJRBJDHSM-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 2
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002048 multi walled nanotube Substances 0.000 description 2
- 239000004584 polyacrylic acid Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002109 single walled nanotube Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910004761 HSV 900 Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
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- 239000006258 conductive agent Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
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- 230000001351 cycling effect Effects 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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 discloses a composite negative electrode layer, which comprises a basic negative electrode plate, wherein at least one surface of the basic negative electrode plate is compounded with an interface layer, the interface layer contains a carbon nano tube material, the carbon nano tube material is of a bent or spiral shape, transition metal nano particles exist at the port of the carbon nano tube material, and the carbon nano tube material is of a hollow structure. The composite negative electrode layer is used in a battery, the high porosity promotes lithium ion transmission, the dense carbon nano tube has high stability, and the interface layer can further prevent lithium dendrites from penetrating through a diaphragm, so that the safety performance of the battery is improved.
Description
Technical Field
The invention relates to the technical field of battery materials, in particular to a composite anode layer, a preparation method and application thereof in batteries.
Background
The carbon nanotube as one-dimensional nanometer material has light weight, perfect hexagonal structure connection and many abnormal mechanical, electrical and chemical properties. Carbon nanotubes, if composed of a single sheet, are also known as single-walled nanotubes (SWNTs); consisting of several concentric sheets, also known as multiwall nanotubes (MWNTs). In recent years, with the deep research of carbon nanotubes and nano materials, the wide application prospect is also continuously shown, and particularly, the conductivity of electrodes (including anodes and cathodes) is enriched as an additive in lithium ion batteries.
When the lithium ion battery is charged and discharged, lithium dendrites are inevitably generated in the repeated deposition and precipitation processes of lithium ions, and the growth of the lithium dendrites not only causes irreversible loss of lithium elements, so that the cycle performance of the battery is weakened, but also can puncture a diaphragm, so that the battery is short-circuited, even fire is caused, and great hidden danger is caused to the use of the lithium metal secondary battery. Therefore, inhibition of lithium dendrite growth has become a highly desirable problem.
Disclosure of Invention
Aiming at the problems in the prior art, the invention discloses a composite anode layer, which comprises a plurality of active sites of a spiral porous nano tube material containing transition metal, wherein the transition metal is distributed at the tube end, the tube diameter is uniformly dispersed, lithium metal is induced to be uniformly deposited, lithium dendrite formation is avoided, and simultaneously, the defect sites of the spiral material are more, especially, the defect sites are increased after N is doped, the sites can promote lithium ions to pass through, and the conductivity is improved without reducing the lithium ion transmission performance. The lithium-philic material is of a spiral nanotube structure, a composite negative electrode layer is formed after the surface of the existing basic negative electrode plate is compounded, transition metal is positioned at a nanotube port on one hand for forming a core for the growth of a carbon nanotube, and on the other hand, when a battery is charged, the uniformly distributed transition metal can not only induce the deintercalation of lithium in the negative electrode, but also timely disperse lithium ions, so that the situation that the lithium ions are not timely embedded between the negative electrode layers and are locally gathered on the surface when the lithium intercalation speed of the negative electrode is too high is avoided; the composite material is used as an interface layer of the basic negative electrode plate, the high porosity promotes lithium ion transmission, the dense nano tube has high stability, the interface layer can further prevent negative electrode lithium dendrite from penetrating through a diaphragm, and the safety performance of the battery is improved.
The invention is realized by the following technical scheme:
the invention provides a composite negative electrode layer, which comprises a basic negative electrode plate, wherein at least one surface of the basic negative electrode plate is compounded with an interface layer, the interface layer contains a carbon nano tube material, the carbon nano tube material is bent or spiral, transition metal nano particles exist at the port of the carbon nano tube material, and the carbon nano tube material is of a hollow structure. The basic negative plate can be a common negative plate and comprises a graphite negative plate, a silicon-containing negative plate and a lithium metal negative plate.
According to the design of the invention, the inventor researches and discovers that the morphology characteristics of the hollow carbon nanotube material can be adjusted, and the further construction of an electron transmission network of the carbon nanotube material can be realized on the premise of less addition. Different active sites and specific surface areas are realized by adjusting the helicity of the carbon nano tube, so that the conductivity of the carbon nano tube material and the liquid absorption rate of electrolyte are improved; the carbon nano tube has uniform tube diameter distribution, can avoid material agglomeration, is beneficial to dispersion, and can improve the resistance, the multiplying power performance and the cycle performance of the battery by only adding a small amount. The transition metal nanoparticles at the ports of the carbon nanotube material are nucleation sites formed by the carbon nanotube material of the present invention. In the in-situ synthesis process of the carbon nano tube, the shape of the carbon nano tube can be controlled to be straight, curved and spiral with different degrees by controlling the synthesis conditions, the screw pitch is uniform when in spiral, and the screw angle changes along with the number of spiral turns, so that the stability of the carbon nano tube is maintained. When the carbon nanotubes are used for improving the conductivity of the silicon material, the carbon nanotubes with high spiral degree are more beneficial to improving the conductivity of the silicon material and inhibiting the expansion because the silicon material has poor conductivity and high expansion compared with the carbon material; when the carbon nano tube is used for the positive electrode active material containing the transition metal, the performance requirement can be met when the carbon nano tube is in a straight line shape, a bent shape or a low-degree spiral shape because the positive electrode has relatively small expansion and the conductivity requirement is smaller than that of a silicon material; when the carbon nano tube is used for a sulfur-containing positive electrode, the high-degree spiral morphology advantage is higher as the mechanism of a silicon negative electrode is similar.
The inventor further researches to compound the carbon nano tube on a basic negative plate to form a compound negative layer, wherein transition metal is positioned at a nano tube port on one hand for forming a core for the growth of the carbon nano tube, and on the other hand, when the battery is charged, the uniformly distributed transition metal can not only induce the deintercalation of lithium in the negative electrode, but also enable lithium ions to be uniformly intercalated to avoid local lithium dendrites; the composite material is used as an interface layer of the composite anode layer, the high porosity promotes lithium ion transmission, the dense nano tube has strong stability, and when the interface layer is arranged between the diaphragm and the anode, the interface layer can be used as an intermediate layer to prevent lithium dendrite from penetrating through the diaphragm, so that the safety performance of the battery is improved; when the interface layer is positioned on the other side of the negative electrode piece and far away from the diaphragm end, lithium can be induced to be embedded into the deep part of the negative electrode, and lithium dendrite formation on the surface of the negative electrode piece near the diaphragm end can be prevented.
As a further scheme, the diameter of the carbon nanotube material is 5nm-100nm. The bending of the carbon nano tube material is facilitated while the electrical property of the carbon nano tube is improved.
As a further aspect, the diameter of the carbon nanotube material is 20nm-40nm.
As a further scheme, the pitch of the carbon nanotube material is 90nm-100nm. The appropriate screw pitch not only can easily realize the stability of the curled carbon nano tube, but also can avoid the influence of difficult dispersion of conductive material agglomeration when the screw pitch is too small, and the internal resistance of the battery is increased because the spacing between active material particles cannot be further reduced after the active material is mixed when the screw pitch is too large, thereby increasing the consumption of the binder and the internal resistance of the battery.
The pitch of the carbon nanotube material in the invention represents the straight line distance between two points corresponding to the centers of the planes of the adjacent two spirals by the spiral coil.
As a further aspect, the helix angle of the carbon nanotube material is 30 ° to 120 °.
The helix angle of the carbon nanotube material in the invention represents a bending angle formed by starting bending growth in a direction deviating from a straight line in the growth process of the nearly straight line by using the growth start point at the end opening of the tube, and the sequentially-appearing spiral bending angles can be respectively represented as theta 1, theta 2 and theta 3.
As a further scheme, the aspect ratio of the carbon nanotube material is 3-1000. When the length-diameter ratio is too small, the performance of the conductive battery is reduced like that of the spherical granular conductive agent; when the aspect ratio is too large, the nanotube structure is liable to be unstable.
As a further proposal, the diameter ratio of the particle size of the transition metal nano particles to the diameter of the carbon nano tube material is (1-1.5): 1-1.5. The diameters of the two are similar, so that the transition metal particles are stably connected to the carbon nano tube ports, and the formation of longer spiral morphology is promoted through the stable chemical bond action.
As a further proposal, the thickness of the interface layer is 2-200 μm. An excessively thick interface layer can increase the distance of an ion transmission path, so that the impedance of a lithium battery is increased, and more irreversible capacity is lost; the too thin interface layer cannot thoroughly inhibit the growth and puncture of dendrites due to lower mechanical strength, and has no obvious modification effect on the negative plate.
As a further alternative, the thickness of the interfacial layer is 5-40 μm.
As a further aspect, the transition metal nanoparticles comprise one or more of transition metals;
as a still further aspect, the transition metal includes one or more of iron, cobalt, nickel, copper, and manganese.
As a further aspect, the transition metal includes one or both of iron and copper. Iron and copper facilitate the formation of multi-coordination bonds.
As a still further aspect, the transition metal is a mixture of iron and copper. The combination of iron and copper is more beneficial in promoting the formation of the helical shape of the carbon nanotubes.
The second aspect of the present invention provides a method for preparing a composite anode layer, comprising the steps of:
s1: uniformly mixing a transition metal-containing lithium-philic material precursor, a carbon source and a nitrogen source, drying, and calcining in an inert atmosphere to obtain an A1 material;
s2: mixing the A1 material obtained in the step S1 with an electrophile and a protonic acid solution under a certain condition, and drying to obtain an A2 material;
s3: and (3) compositing the A2 material obtained in the step (S2) with at least one surface of the basic negative plate, so that the A2 material is uniformly covered on at least one surface of the negative plate, and obtaining the composite negative plate.
In the method, a transition metal-containing lithium-philic material precursor, a carbon source and a nitrogen source are calcined at high temperature, so that non-spiral Carbon Nanotubes (CNTs) which are short and straight tend to be easily obtained, and then the carbon nanotubes are treated under the combined action of an electrophile and protonic acid, so that a curved or spiral carbon nanotube material is obtained. The transition metal salt is reduced by the carbon source during high temperature calcination to form the transition metal nanoparticles. The transition metal and the carbon nitrogen form coordination bonds, more carbon nitrogen fragments are adsorbed to migrate to the transition metal nano particles and grow gradually, other irregular structural fragments or particles are formed in the process, and in the S2 step, the particles, chain-shaped and irregular annular fragments which do not form a tube are subjected to electrophilic reagent and protonic acid mixing treatment, so that the nano tubes are further promoted to stably form a bending shape with a certain degree of helicity, and even form a helix shape which is stable to different degrees through the rupture and recombination of chemical bonds. In addition, in the step S2, defective sites in the tube are filled by fragments, and the originally separated tubes are caused to be combined together by metal complexation effect, so that the tube is prolonged, the appearance is more dense and uniform, and the carbon nano tubes are crosslinked to form a stable structure by the comprehensive coordination of multiple bond energies. In the S3 step, the composite material is used as an interface layer of the composite negative plate, the high porosity promotes lithium ion transmission, the dense nano tube has high stability, the interface layer can further prevent lithium dendrites from penetrating through a diaphragm, the safety performance of the battery is improved, when the interface layer is loaded on two sides of the negative plate, one side of the interface layer material far away from the diaphragm can attract part of lithium to be deposited on one side close to the interface layer, lithium precipitation on the surface of the negative electrode is prevented, and the performance of the battery is further improved.
As a further scheme, the precursor of the lithium-philic material in S1 is selected from transition metal inorganic salts.
As a still further aspect, at least one of the transition metal chloride, the transition metal nitrate, the transition metal acetate, and the transition metal fluoride.
As a further scheme, the carbon source in S1 includes at least one of biomass carbon source, carbon powder, graphene and activated carbon.
As a further scheme, the nitrogen source in S1 includes one or more of nitrogen-containing heterocycle and its derivative, guanidine salt derivative.
As a further scheme, the electrophilic reagent solution in S2 includes at least one of aluminum chloride, aluminum sulfate, boron trifluoride, sulfur trioxide, ferric bromide, titanium bromide, tin chloride, zinc chloride, ferric trichloride, and molybdenum pentachloride.
As a further scheme, the protonic acid solution in S2 includes at least one of formic acid, trifluoroacetic acid, oxalic acid, hydrochloric acid, sulfuric acid, citric acid, camphorsulfonic acid, and benzoic acid. Under the combined action of no electrophile and proton acid, the carbon nano tube tends to be in a relatively short eccentric line shape, the helicity of the carbon nano tube is improved after the step of adding S2, and each turning part of the carbon nano tube with high helicity can form a new topological structure active site, so that the conductivity is improved.
As a further scheme, in S1, besides the carbon source and the nitrogen source are uniformly mixed, other nonmetallic sources are also included, and the other nonmetallic sources are one or more of a phosphorus source and a fluorine source. P, F is easy to form a coordination bond with transition metal, so that the active site is further improved, the formation of nano tubes is promoted, the porosity of the material is increased, and the ion transmission, the conductivity and the safety of an interface layer are comprehensively improved. The phosphorus source is an organic or inorganic substance containing phosphorus, and the fluorine source is an organic or inorganic substance containing fluorine, typically but not limited to, for example, the phosphorus source is at least one of triphenylphosphine, tetraphenylphosphonium bromide, sodium 1-butyl-3-methylimidazolium hexafluorophosphate, hydrogen phosphide, sodium phosphate, sodium phosphite, elemental phosphorus, sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium hydrogen phosphite and phosphoric acid, and the fluorine source is at least one of hydrogen fluoride, lithium fluoride, ammonium fluoride, sodium fluoride, ammonium fluoride, potassium fluoride, aluminum fluoride, magnesium fluoride, sodium fluoride, calcium fluoride, tetrabutylammonium fluoride, triethylmethoxyammonium fluoride, ammonium fluoroborate, tetrabutylammonium fluoroborate and polyvinylidene fluoride.
As a further scheme, the carbon source, the nitrogen source, other non-metal sources and the precursor of the lithium-philic material have the molar ratio of carbon, nitrogen, other non-metal and transition metal elements of (5-20): (50-150): (5-50): (1-5).
As a further proposal, the carbon source, the nitrogen source, the other non-metal source and the precursor of the lithium-philic material have the molar ratio of carbon, nitrogen, other non-metal and transition metal elements of (5-20): 50-120): 5-50): 1-5. At this ratio, the resulting carbon nanotube helix is suitable, the ionic conductivity and the electronic conductivity of the negative electrode interface are both good, the comprehensive performance is good, the electronic conductivity is insufficient when the relative ratio of nitrogen is lower than 50, the nanotubes tend to be more linear, the too long and denser porosity decrease of the tubes gradually starts to inhibit lithium ion transmission when the relative ratio of nitrogen exceeds 120, and the electronic conductivity is better but the ionic conductivity slightly decreases.
As a further scheme, the mass ratio of the A1 material to the electrophilic reagent solution to the protonic acid solution in the S2 is 1 (5-10): 10-200.
As a further scheme, the calcination temperature in the S1 is 500-800 ℃ and the calcination time is 2-10 h. When the calcination temperature is too high, the metal-nitrogen bond is broken, and the performance is lowered.
As a further scheme, the calcination temperature in the step S1 is kept at 550 ℃ for 2 hours, and the temperature is continuously increased to 750 ℃ for 2 hours. Calcination at the staged temperature may allow nucleation and tube growth reactions to proceed more fully.
As a further scheme, the temperature of the treatment in the step S2 is 10-100 ℃, and the reaction time is 1-20 h.
As a further scheme, the S3 is coated by adopting preparation slurry, and the mass ratio of the A2 material in the slurry is not less than 80%.
A third aspect of the present invention is to provide a battery or an electrochemical device having the composite anode layer and the composite anode layer prepared by the method of preparing the same.
The invention has the characteristics and beneficial effects that:
(1) The spiral porous nano tube material containing transition metal has more active sites, the transition metal is distributed at the tube end, the tube diameter is uniformly dispersed, and the spiral material has more defect sites, especially the defect sites are increased after N is doped, the sites can promote lithium ions to pass through, and the conductivity is improved without reducing the transmission performance of the lithium ions. The lithium-philic material is of a spiral nanotube structure, a composite negative electrode layer structure is formed after the surface of a basic negative electrode plate is compounded, transition metal is positioned at a nanotube port on one hand for forming a core for carbon nanotube growth, and on the other hand, when a battery is charged, uniformly distributed transition metal can not only induce the deintercalation of lithium ions, but also enable the uniform intercalation of lithium ions to avoid the formation of local lithium dendrites; the composite material is used as an interface layer of the composite anode layer, the high porosity promotes lithium ion transmission, the dense nano tube has high stability, the interface layer can further prevent lithium dendrites from penetrating through a diaphragm, and the safety performance of the battery is improved.
(2) The method for preparing the composite negative plate is simple and efficient, and is beneficial to mass production.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a view of a negative electrode sheet obtained by disassembling a battery after 200 weeks of cycling and full charge;
FIG. 2 is a 500nm Scanning Electron Microscope (SEM), 100nm Transmission Electron Microscope (TEM), and a corresponding high power mirror (2 nm) transmission electron microscope (HTEM) at the end of a carbon nanotube of the A2 material of example 1;
FIG. 3a is a Transmission Electron Microscope (TEM) of the A2 material of example 4; FIG. 3b is a Transmission Electron Microscope (TEM) of the A2 material of example 5;
FIG. 4 is a Scanning Electron Microscope (SEM) image of 1 μm of the A2 material of comparative example 1 and a Transmission Electron Microscope (TEM) image of 100nm of the A2 material of comparative example 3;
FIG. 5 is a sectional view of a composite negative plate scanning electron microscope (CP-SEM) of example 1;
Detailed Description
In order to facilitate understanding of a composite negative electrode layer according to the present invention, the following more complete description of the composite negative electrode layer according to the present invention will be given, but the embodiment of the present invention (taking a sheet obtained by compounding an interface layer with a silicon-oxygen negative electrode sheet as an example of the composite negative electrode sheet) is not limited to the scope of the present invention.
Example 1:
s1: and (3) weighing a certain amount of sucrose, dicyandiamide and ferric nitrate nonahydrate according to the molar ratio of the carbon to the nitrogen to the transition metal being 10:100:1, dissolving in absolute ethyl alcohol, drying at 70 ℃ to obtain solid powder, transferring the solid powder into a tubular furnace, keeping the solid powder in a nitrogen atmosphere at 550 ℃ for calcination for 2 hours, and continuously heating up to 750 ℃ for 2 hours to obtain the A1 material.
S2: and adding the A1 material obtained after cooling to room temperature into a mixed solution of aluminum trichloride and trifluoroacetic acid (the mass ratio is 1:10:200), uniformly mixing, heating at 45 ℃ for 20 hours, and filtering and drying to obtain the A2 material.
S3: a2 material of S2, CMC, SBR (98% by weight: 1.5% by weight: 0.5%) were prepared as a slurry and then applied to one side of a silicone negative electrode sheet, with an average thickness of about 5 μm.
Example 2:
lithium fluoride was additionally added to example 1 as carbon: nitrogen: fluorine: the molar ratio of iron is 10:100:5:1, otherwise identical.
Example 3:
the same applies to both sides of the silicone negative electrode sheet in S3 of example 1 instead.
Example 4:
the same applies to example 1 except that 1:10:200 in S2 is changed to 1:5:200.
Example 5:
the procedure was the same as in example 1 except that the heating at 45℃was changed from heating at 45℃for 20 hours to heating at 45℃for 10 hours.
Example 6:
the coating in example 1 was changed to be applied only to the other side of the silicone negative electrode sheet, and the other was the same.
Example 7:
the coating in example 1 was changed to an average thickness of 200 μm, and the other was the same.
Comparative example 1:
the ferric nitrate nonahydrate was removed in example 1, except that the same was made.
Comparative example 2:
the dicyandiamide was removed in example 1, and the same was repeated.
Comparative example 3:
the aluminum trichloride was removed in example 1, and the same was repeated.
Comparative example 4:
the calcination temperature in example 1 was changed to 900℃and the same applies to the other.
Comparative example 5:
in example 1, a silicon oxide negative electrode sheet was directly used as the negative electrode, and an interfacial layer coating was not applied.
Comparative example 6:
an equivalent amount of commercially available carbon nanotube material (available from Shenyang tandem nanotechnology Co., ltd.) was used in place of the A2 material of example 1.
The obtained composite negative electrode plate and the lithium cobaltate positive electrode plate are assembled into a soft package battery, and the battery is tested and compared:
preparation of the battery:
and (3) a positive electrode: lithium cobalt oxide (LiCoO) 2 ) Preparing positive electrode slurry by the proportion of +carbon black (SP) +polyvinylidene fluoride (HSV 900) (the mass ratio is 97.5:1.5:1) and coating the positive electrode slurry on aluminum foil to prepare a positive electrode plate;
and (3) a negative electrode: the composite negative plate composed of the interface layer and the silica negative plate in the embodiment above; wherein the silica negative electrode sheet is silica-mixed graphite negative electrode material (silica-graphite mass ratio 9:1) according to mass ratio: carbon nanotube material: SBR (styrene butadiene rubber): the negative electrode paste was prepared at a ratio of PAA (polyacrylic acid) =96%: 1%:0.5%:2.5%, and was coated on a copper foil and dried to prepare a negative electrode sheet.
Assembling a battery: the separator was a 16 μm thick PP separator. Electrolyte 1M LiPF 6 Lithium hexafluorophosphate (EC) and EMC (methyl ethyl carbonate) and DMC (dimethyl carbonate) (the mass ratio is 1:1:1), assembling into a soft package battery, and performing constant current charge and discharge test in a voltage range of 2.75V-4.5V; the 3C/0.3C first-cycle discharge capacity retention rate represents the retention rate of the first-cycle discharge capacity of the charge-discharge program of 3C charge and 0.3C discharge relative to the 0.3C/0.3C first-cycle discharge capacity, and is used for detecting the rate capability of the battery 3C;the discharge capacity retention rate of the nth turn was calculated as 100% of the 0.3C first turn discharge capacity retention rate.
According to the lithium separation grades, the lithium separation conditions are divided into 7 grades according to the severity, the higher the numerical value is, the more serious the lithium separation degree is, and the total lithium separation conditions of the 7 grades can be distinguished as shown in the table 1:
TABLE 1 negative electrode lithium precipitation conditions
| Grade | Lithium evolution condition |
| 0 | Lithium is not separated out; |
| 1 | slightly separating out lithium, wherein the coverage rate of lithium on the surface of the negative electrode is 1-15%; |
| 2 | small part of lithium is separated, and the coverage rate of lithium on the surface of the cathode is 16-30%; |
| 3 | partially analyzing lithium, wherein the coverage rate of lithium on the surface of the negative electrode is 31% -50%; |
| 4 | most of lithium is separated out, and the coverage rate of lithium on the surface of the negative electrode is between 51% and 65%; |
| 5 | most of lithium is separated out, and the coverage rate of lithium on the surface of the negative electrode is 66% -90%; |
| 6 | almost all lithium is separated out, and the coverage rate of lithium on the surface of the negative electrode is 91-100%; |
and (3) verification result analysis:
table 2 test results of inventive examples and comparative examples
The invention discloses a composite negative electrode layer, which comprises a basic negative electrode plate, wherein at least one surface of the basic negative electrode plate is compounded with an interface layer, the interface layer contains a carbon nano tube material, the carbon nano tube material is of a bent or spiral shape, transition metal nano particles exist at the port of the carbon nano tube material, and the carbon nano tube material is of a hollow structure. The composite negative electrode layer is used in a battery, the high porosity promotes lithium ion transmission, the dense carbon nano tube has high stability, and the interface layer can further prevent lithium dendrites from penetrating through a diaphragm, so that the safety performance of the battery is improved.
The composite negative electrode layer obtained by the invention is used in a battery, a series of tests are carried out, the battery is circulated for 200 weeks and is fully charged, then the composite negative electrode sheet is disassembled, the lithium precipitation condition of the negative electrode is shown in table 1 and fig. 1, and the charge and discharge electrical performance test data of the battery are shown in table 2. The composite electrode plates obtained in the examples 1-7 of the invention have the electric performance in the battery which is obviously better than that of the batteries of the comparative examples 1-6, and the negative electrode plates of the examples 1-7 are obviously improved relative to the lithium precipitation conditions of the comparative examples 1-6 under the same conditions. The main reason is that the interfacial layer material of the present invention has a curled curved or spiral morphology as shown in fig. 2-3. The spiral porous nano tube material containing transition metal has more active sites, the transition metal is distributed at the tube end, the tube diameter is uniformly dispersed, lithium ions are induced to be uniformly deintercalated, lithium dendrite formation is avoided, and simultaneously, the spiral material has more defect sites, especially the defect sites are increased after N is doped, the sites can promote lithium ions to pass through, and the conductivity is improved without reducing the lithium ion transmission performance. The transition metal is positioned at the port of the nano tube for forming the core for the growth of the carbon nano tube on one hand, and on the other hand, when the battery is charged, the uniformly distributed transition metal can not only induce the deintercalation of lithium in the anode, but also disperse lithium ions which do not enter the anode layer so as to avoid local lithium aggregation; the carbon nano tube material is used as an interface layer, the high porosity promotes lithium ion transmission, the dense nano tube has high stability, the interface layer can further prevent lithium dendrite from penetrating through a diaphragm, and the safety performance of the battery is improved. Therefore, the invention of example 1-example 7 has better electrical performance. In addition, the morphological characteristics of the carbon nano tube also increase the active site and the specific surface area of the carbon nano tube, and are beneficial to improving the liquid absorption rate of the carbon nano tube material to the electrolyte, so that the wettability of the cathode is beneficial to improving, the multiplying power performance and the cycle performance of the battery are further improved, the side reaction of the cathode material and the electrolyte is inhibited, the gas production is reduced, and the safety performance of the battery is improved. In comparative example 1, since the transition metal salt was not added (as in fig. 4-1 μm sem), nucleation sites could not be formed at the ports, and thus, carbon nanotubes could not be formed finally, and the battery performance was greatly reduced. Comparison of example 1, example 3 and example 6 shows that the effect of the interface layer on the battery performance on which side of the basic negative electrode sheet is not much different when single-sided coating is performed, and the battery performance is better when double-sided simultaneous coating is performed than when single-sided coating is performed. Further comparing example 1 with example 7, an excessively thick interfacial layer increases the distance of the ion transport path, increasing the impedance of the lithium battery, resulting in more irreversible capacity loss, and thus the solution of example 7 results in a small amount of lithium evolution from the final pole piece.
In the method of the invention, electrophilic reagent solution and protonic acid solution are further added, and the mixed treatment of electrophilic reagent solution and protonic acid is found, so that on one hand, irregular annular fragments such as particles, chain, five-membered or seven-membered rings and the like which are not completely formed into tubes can further promote the carbon nano tube to form a bending shape with a certain helicity through the rupture and recombination of chemical bonds, and even form a stable helicity with different degrees; on the other hand, the defect sites in the carbon nano tube can be filled by fragments, and the originally separated tubes are promoted to be combined together by the metal complexing effect, so that the tubes are prolonged, the appearance is more dense and uniform, and the carbon nano tube is crosslinked to form a stable structure by the multiple bond energy comprehensive coordination effect, as shown in figure 3. Comparative example 1 and comparative example 3, after removal of the electrophile, did not co-act with the protonic acid, and were disadvantageous in that long spiral nanotubes were formed to precipitate lithium from the negative electrode, and battery performance was degraded.
We also add a nitrogen source during the preparation process, although nitrogen is not a necessary condition for the formation of the tube shape, nitrogen doping can increase the active sites, promoting the formation of a more dense tube shape. We verify the findings by comparing example 1-example 7 with comparative example 2. The batteries of examples 1 to 7 are superior to comparative example 2 in both rate performance and cycle performance, particularly in long cycle process, and as charge and discharge are continued, the addition of no nitrogen causes instability of nanotubes, and also there is no way to well inhibit the generation of lithium dendrites in the battery.
The fluorine source is added in the preparation process, and although fluorine is not a necessary condition for forming the tube shape, the fluorine has strong polarity, and is easy to form a matched bond with transition metal, so that active sites are further increased, more dense tube shapes are promoted to be formed, and meanwhile, the polarization of the battery and the internal resistance of the battery can be reduced. Comparison of example 1 and example 2 shows that the rate performance and the cycle performance of the battery of example 2 are better than those of example 1, and the addition of fluorine is proved to actually further improve the battery performance.
Finally, the formation of carbon nanotubes was not separated from the sintering process, and we found that the electrical properties of the cells of examples 1-7 were better than that of comparative example 4 by comparing examples 1-7 with comparative example 4. It is believed that when the temperature is greater than 800 c, most of the metal ions do not remain coordinated with the original nanotube structure, the metal-nitrogen bonds are broken, more fragments are formed, and a tubular structure is not easily formed, resulting in a decrease in performance.
In summary, the carbon nanotubes with certain helicity and bending or high helicity are used in the negative electrode interface layer of the battery, so that not only can the electrical performance of the battery be improved, but also the generation of lithium dendrite of the battery can be reduced.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The composite negative electrode layer is characterized by comprising a basic negative electrode plate, wherein at least one surface of the basic negative electrode plate is composited with an interface layer, the interface layer contains carbon nanotube materials, the carbon nanotube materials are in a bent shape or a spiral shape, transition metal nano particles exist at the port of the carbon nanotube materials, and the carbon nanotube materials are in a hollow structure.
2. The composite anode layer according to claim 1, wherein the carbon nanotube material has a diameter of 5nm to 100nm;
further preferably, the diameter of the carbon nanotube material is 20nm to 40nm.
3. The composite anode layer according to claim 1, wherein the pitch of the carbon nanotube material is 90nm to 100nm;
further preferably, the helix angle of the carbon nanotube material is 30 ° -120 °.
4. The composite anode layer according to claim 1, wherein the aspect ratio of the carbon nanotube material is not less than 3;
further preferably, the ratio of the particle diameter of the transition metal nanoparticle to the diameter of the carbon nanotube is (1-1.5): 1-1.5.
5. The composite anode layer according to claim 1, wherein the thickness of the interfacial layer is 2-200 μm;
further preferably, the thickness of the interface layer is 5-40 μm;
the transition metal nanoparticles include one or more of transition metals;
further preferably, the transition metal comprises one or more of iron, cobalt, nickel, copper, manganese;
still more preferably, the transition metal comprises one or both of iron and copper.
6. A method for preparing the composite anode layer according to claim 1-claim 5, comprising the steps of:
s1: uniformly mixing a transition metal-containing lithium-philic material precursor, a carbon source and a nitrogen source, drying, and calcining in an inert atmosphere to obtain an A1 material;
s2: mixing the A1 material obtained in the step S1 with an electrophile and a protonic acid solution under a certain condition, and drying to obtain an A2 material;
s3: and (3) compositing the A2 material obtained in the step (S2) with at least one surface of the basic negative plate, so that the A2 material is uniformly covered on at least one surface of the basic negative plate, and obtaining the composite negative plate.
7. The method for preparing a composite anode layer according to claim 6, wherein the precursor of the lithium-philic material in S1 is selected from transition metal inorganic salts;
further preferably, the transition metal inorganic salt includes at least one of a transition metal chloride, a transition metal nitrate, a transition metal acetate, and a transition metal fluoride;
the carbon source in the S1 comprises at least one of biomass carbon source, carbon powder, graphene and activated carbon;
the nitrogen source in S1 comprises one or more of nitrogen-containing heterocycle and its derivative, guanidine salt derivative;
the electrophilic reagent solution in the step S2 comprises at least one of aluminum chloride, aluminum sulfate, boron trifluoride, sulfur trioxide, ferric bromide, titanium bromide, stannic chloride, zinc chloride, ferric trichloride and molybdenum pentachloride;
the protonic acid solution in S2 includes at least one of formic acid, trifluoroacetic acid, oxalic acid, hydrochloric acid, sulfuric acid, citric acid, camphorsulfonic acid, and benzoic acid.
8. The method for preparing a composite anode layer according to claim 6, wherein the step S1 comprises other nonmetallic sources in addition to the carbon source and the nitrogen source, and the other nonmetallic sources are one or more of phosphorus source and fluorine source;
the phosphorus source is an organic or inorganic substance containing phosphorus, and the fluorine source is an organic or inorganic substance containing fluorine;
further preferably, the phosphorus source is at least one of triphenylphosphine, tetraphenylphosphonium bromide, sodium 1-butyl-3-methylimidazolium phosphate, hydrogen phosphide, sodium phosphate, sodium phosphite, elemental phosphorus, sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium hydrogen phosphite and phosphoric acid, and the fluorine source is at least one of hydrogen fluoride, lithium fluoride, ammonium fluoride, sodium fluoride, ammonium fluoride, potassium fluoride, aluminum fluoride, magnesium fluoride, sodium fluoride, calcium fluoride, tetrabutylammonium fluoride, triethylmethoxymethyl ammonium fluoride, ammonium fluoroborate, tetrabutylammonium fluoroborate and polyvinylidene fluoride;
the carbon source, the nitrogen source, other non-metal sources and the lithium-philic material precursor contain carbon, nitrogen and other non-metal and transition metal elements in the molar ratio of (5-20): (50-150): (5-50): (1-5);
further preferably, the carbon source, the nitrogen source, the other non-metal sources and the precursor of the lithium-philic material have the molar ratio of carbon, nitrogen, other non-metal and transition metal elements of (5-20): 50-120): 5-50): 1-5;
in the S2, the mass ratio of the A1 material to the electrophilic reagent solution to the protonic acid solution is 1 (5-10) (10-200).
9. The method for preparing a composite anode according to claim 6, wherein the calcination temperature in S1 is 500 ℃ to 800 ℃ and the calcination time is 2h to 10h;
further preferably, the calcination temperature in S1 is 550 ℃ for 2 hours, and the temperature is continuously raised to 750 ℃ for 2 hours;
the temperature of the treatment in the step S2 is 10-100 ℃, and the reaction time is 1-20 h;
in the step S3, the composite material A2 is used for preparing slurry for coating, and the mass ratio of the material A2 in the slurry is not less than 80%.
10. A battery or an electrochemical device having the composite anode layer according to any one of claims 1 to 5 and the composite anode layer prepared by the preparation method according to any one of claims 6 to 9.
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