CN113437265A - Positive active material for lithium battery and preparation method thereof - Google Patents
Positive active material for lithium battery and preparation method thereof Download PDFInfo
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- CN113437265A CN113437265A CN202010206982.5A CN202010206982A CN113437265A CN 113437265 A CN113437265 A CN 113437265A CN 202010206982 A CN202010206982 A CN 202010206982A CN 113437265 A CN113437265 A CN 113437265A
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- CN
- China
- Prior art keywords
- active material
- positive active
- lithium battery
- shell
- preparing
- Prior art date
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- 239000007774 positive electrode material Substances 0.000 title claims abstract description 139
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 109
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 109
- 238000002360 preparation method Methods 0.000 title claims abstract description 29
- 239000002243 precursor Substances 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims abstract description 28
- 239000011258 core-shell material Substances 0.000 claims abstract description 26
- 239000000126 substance Substances 0.000 claims description 43
- 238000005245 sintering Methods 0.000 claims description 40
- 239000003513 alkali Substances 0.000 claims description 35
- 150000001875 compounds Chemical class 0.000 claims description 29
- 238000002156 mixing Methods 0.000 claims description 27
- 230000014759 maintenance of location Effects 0.000 claims description 26
- 229910052782 aluminium Inorganic materials 0.000 claims description 24
- 238000001816 cooling Methods 0.000 claims description 24
- 239000000203 mixture Substances 0.000 claims description 21
- 239000000243 solution Substances 0.000 claims description 20
- 239000007864 aqueous solution Substances 0.000 claims description 18
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 238000004140 cleaning Methods 0.000 claims description 13
- 239000003792 electrolyte Substances 0.000 claims description 11
- 238000000227 grinding Methods 0.000 claims description 11
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 10
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 10
- 229910001416 lithium ion Inorganic materials 0.000 claims description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 9
- 239000004094 surface-active agent Substances 0.000 claims description 9
- 229910052783 alkali metal Inorganic materials 0.000 claims description 8
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 8
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 7
- 229910052723 transition metal Inorganic materials 0.000 claims description 7
- 150000003624 transition metals Chemical class 0.000 claims description 7
- 239000002270 dispersing agent Substances 0.000 claims description 6
- 229910052749 magnesium Inorganic materials 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- 229910052706 scandium Inorganic materials 0.000 claims description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- 229910052772 Samarium Inorganic materials 0.000 claims description 5
- 238000000137 annealing Methods 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229910052792 caesium Inorganic materials 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 229910052712 strontium Inorganic materials 0.000 claims description 4
- 229910052718 tin Inorganic materials 0.000 claims description 4
- 229910052721 tungsten Inorganic materials 0.000 claims description 4
- 229910052727 yttrium Inorganic materials 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- NWGKJDSIEKMTRX-AAZCQSIUSA-N Sorbitan monooleate Chemical group CCCCCCCC\C=C/CCCCCCCC(=O)OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O NWGKJDSIEKMTRX-AAZCQSIUSA-N 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 229910052715 tantalum Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 19
- 230000008569 process Effects 0.000 abstract description 10
- 238000004519 manufacturing process Methods 0.000 abstract 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 117
- 239000011572 manganese Substances 0.000 description 75
- 230000000052 comparative effect Effects 0.000 description 37
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 24
- 229910052751 metal Inorganic materials 0.000 description 24
- 239000002184 metal Substances 0.000 description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 229910052748 manganese Inorganic materials 0.000 description 20
- 239000013078 crystal Substances 0.000 description 19
- 238000012360 testing method Methods 0.000 description 19
- 229910052759 nickel Inorganic materials 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 16
- 239000000047 product Substances 0.000 description 15
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 14
- 238000009616 inductively coupled plasma Methods 0.000 description 14
- 239000002245 particle Substances 0.000 description 14
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 12
- 238000004458 analytical method Methods 0.000 description 12
- 239000001569 carbon dioxide Substances 0.000 description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 description 12
- 229910052808 lithium carbonate Inorganic materials 0.000 description 11
- 230000001351 cycling effect Effects 0.000 description 9
- 239000011777 magnesium Substances 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 8
- 229910021645 metal ion Inorganic materials 0.000 description 8
- 238000005406 washing Methods 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 239000011164 primary particle Substances 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 239000012086 standard solution Substances 0.000 description 6
- 238000010998 test method Methods 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 239000010406 cathode material Substances 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 description 4
- 229910019421 CoxAly Inorganic materials 0.000 description 4
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 4
- 239000012752 auxiliary agent Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 150000001868 cobalt Chemical class 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 description 4
- 238000001914 filtration Methods 0.000 description 4
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 4
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 description 4
- 150000002696 manganese Chemical class 0.000 description 4
- 150000002815 nickel Chemical class 0.000 description 4
- 229910016401 Ni0.34Co0.33Mn0.33 Inorganic materials 0.000 description 3
- 239000011149 active material Substances 0.000 description 3
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- 239000006182 cathode active material Substances 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 239000003292 glue Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- 239000012798 spherical particle Substances 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 2
- 229910017166 Ni0.815CO0.15Al0.035 Inorganic materials 0.000 description 2
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 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 description 2
- 239000006183 anode active material Substances 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 238000000975 co-precipitation Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Chemical compound [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- KJFMBFZCATUALV-UHFFFAOYSA-N phenolphthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2C(=O)O1 KJFMBFZCATUALV-UHFFFAOYSA-N 0.000 description 2
- 229920001223 polyethylene glycol 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
- 238000001556 precipitation Methods 0.000 description 2
- 238000010079 rubber tapping Methods 0.000 description 2
- 239000011163 secondary particle Substances 0.000 description 2
- 229910052596 spinel Inorganic materials 0.000 description 2
- 239000011029 spinel Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 229910021380 Manganese Chloride Inorganic materials 0.000 description 1
- GLFNIEUTAYBVOC-UHFFFAOYSA-L Manganese chloride Chemical compound Cl[Mn]Cl GLFNIEUTAYBVOC-UHFFFAOYSA-L 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 229910017023 Ni0.88CO0.08Mn0.04 Inorganic materials 0.000 description 1
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- PFYQFCKUASLJLL-UHFFFAOYSA-N [Co].[Ni].[Li] Chemical compound [Co].[Ni].[Li] PFYQFCKUASLJLL-UHFFFAOYSA-N 0.000 description 1
- QTHKJEYUQSLYTH-UHFFFAOYSA-N [Co]=O.[Ni].[Li] Chemical compound [Co]=O.[Ni].[Li] QTHKJEYUQSLYTH-UHFFFAOYSA-N 0.000 description 1
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 description 1
- HDYRYUINDGQKMC-UHFFFAOYSA-M acetyloxyaluminum;dihydrate Chemical compound O.O.CC(=O)O[Al] HDYRYUINDGQKMC-UHFFFAOYSA-M 0.000 description 1
- 238000002479 acid--base titration Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- SMZOGRDCAXLAAR-UHFFFAOYSA-N aluminium isopropoxide Chemical compound [Al+3].CC(C)[O-].CC(C)[O-].CC(C)[O-] SMZOGRDCAXLAAR-UHFFFAOYSA-N 0.000 description 1
- 229940009827 aluminum acetate Drugs 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229940011182 cobalt acetate Drugs 0.000 description 1
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 1
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 1
- 229940044175 cobalt sulfate Drugs 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000001095 inductively coupled plasma mass spectrometry Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 235000015110 jellies Nutrition 0.000 description 1
- 239000008274 jelly Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000006138 lithiation reaction Methods 0.000 description 1
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- BDKWOJYFHXPPPT-UHFFFAOYSA-N lithium dioxido(dioxo)manganese nickel(2+) Chemical compound [Mn](=O)(=O)([O-])[O-].[Ni+2].[Li+] BDKWOJYFHXPPPT-UHFFFAOYSA-N 0.000 description 1
- 229910002102 lithium manganese oxide Inorganic materials 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- VLXXBCXTUVRROQ-UHFFFAOYSA-N lithium;oxido-oxo-(oxomanganiooxy)manganese Chemical compound [Li+].[O-][Mn](=O)O[Mn]=O VLXXBCXTUVRROQ-UHFFFAOYSA-N 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 1
- 235000019341 magnesium sulphate Nutrition 0.000 description 1
- 229940071125 manganese acetate Drugs 0.000 description 1
- 239000011565 manganese chloride Substances 0.000 description 1
- 235000002867 manganese chloride Nutrition 0.000 description 1
- 229940099607 manganese chloride Drugs 0.000 description 1
- 229940099596 manganese sulfate Drugs 0.000 description 1
- 239000011702 manganese sulphate Substances 0.000 description 1
- 235000007079 manganese sulphate Nutrition 0.000 description 1
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 description 1
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 description 1
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 description 1
- QCAWEPFNJXQPAN-UHFFFAOYSA-N methoxyfenozide Chemical compound COC1=CC=CC(C(=O)NN(C(=O)C=2C=C(C)C=C(C)C=2)C(C)(C)C)=C1C QCAWEPFNJXQPAN-UHFFFAOYSA-N 0.000 description 1
- CEQFOVLGLXCDCX-WUKNDPDISA-N methyl red Chemical compound C1=CC(N(C)C)=CC=C1\N=N\C1=CC=CC=C1C(O)=O CEQFOVLGLXCDCX-WUKNDPDISA-N 0.000 description 1
- 229940078494 nickel acetate Drugs 0.000 description 1
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 1
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 1
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920000223 polyglycerol Polymers 0.000 description 1
- -1 polyoxyethylene octylphenol Polymers 0.000 description 1
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 150000003346 selenoethers Chemical class 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 230000007847 structural defect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- XSOKHXFFCGXDJZ-UHFFFAOYSA-N telluride(2-) Chemical compound [Te-2] XSOKHXFFCGXDJZ-UHFFFAOYSA-N 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- OBROYCQXICMORW-UHFFFAOYSA-N tripropoxyalumane Chemical compound [Al+3].CCC[O-].CCC[O-].CCC[O-] OBROYCQXICMORW-UHFFFAOYSA-N 0.000 description 1
Images
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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
-
- 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
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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- 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
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- 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 present invention relates to a positive active material for a lithium battery and a method for preparing the same, the method for preparing the positive active material for a lithium battery comprising: preparing a nuclear precursor; adding a doping material M4 to prepare a shell precursor; adding lithium source to sinter to obtain target product Lia(Ni1‑x‑yCoxM1y)O2]d·[Lis(Ni1‑m‑n‑ tComM2nM4t)O2]1‑d. The lithium battery with the core-shell structure synthesized by the preparation method of the inventionThe positive electrode active material has excellent cycle performance. The preparation method has simple process and controllable process, and is easy for industrial mass production.
Description
Technical Field
The invention belongs to the field of lithium ion batteries, and particularly relates to a positive active material for a lithium battery and a preparation method thereof.
Background
With the popularization of new energy automobiles, the power type lithium ion battery is greatly developed, and meanwhile, the high requirements of the new energy automobiles on the endurance mileage and the energy density, the high cycle performance and the high safety performance of the new energy automobiles are also high. The positive active material for a lithium battery is one of the key materials of the lithium ion battery and is also a key factor hindering the energy density of the lithium ion battery.
At present, most of materials produced by anode material manufacturers at home and abroad are secondary particles formed by agglomeration of fine grains. However, secondary spherical particles present some problems to be solved: (1) the structure of the secondary ball is poor in structural firmness, and the secondary ball is easy to break when being pressed by high pressure in the electrode preparation process, so that particles in the material are exposed, side reaction with electrolyte is intensified, metal ions are dissolved out, and the electrochemical performance is reduced; (2) the primary particles forming the secondary spheres have small particle size and many structural defects, and are easy to collapse under the condition of high voltage and sufficiency; (3) the interior of the secondary spherical particles is difficult to modify in structure, and interface side reaction is difficult to inhibit in the charging and discharging process; (4) the secondary spherical particles easily cause problems such as air expansion.
Researches find that the single-crystal-morphology cathode material not only has higher specific capacity and cycling stability under high voltage, but also can effectively improve the problems of the material in the aspects of high-temperature performance, gas expansion and the like compared with the traditional ternary cathode material with a secondary sphere structure, and meanwhile, the single-crystal cathode material also has the following advantages: (1) high mechanical strength, not easy to be broken in the electrode compacting process, and the compacted density can reach 3.8g/cm3～4.0g/cm3The higher compaction density can reduce the internal resistance of the material, reduce the polarization loss, prolong the cycle life of the battery and improve the energy density of the battery; (2) the special shape of primary single crystal particles has low specific surface area, and the side reaction between the material and the electrolyte is effectively reduced; (3) the surface of the single crystal particles is smooth, the single crystal particles are more fully contacted with the conductive agent, and the lithium ion transmission is facilitated. Therefore, the research on the single crystal cathode material will become a new direction for the research on the lithium ion battery material.
Disclosure of Invention
In view of the above, embodiments of the present invention provide a positive active material for a lithium battery and a method for preparing the same.
The invention provides a positive active material for a lithium battery, which has a core-shell structure and has a chemical formula shown in formula (I):
[Lia(Ni1-x-yCoxM1y)O2]d·[Lis(Ni1-m-nComM2nM4t)O2]1-d (I)
Lia(Ni1-x-yCoxM1y)O2is a chemical formula of a core of the positive active material for a lithium battery, Lis(Ni1-m-n-tComM2nM4t)O2Is a chemical formula of a shell of the positive active material for a lithium battery; the M1 and M2 are respectively and independently selected from Mn and/or Al; the M4 is selected from one or more of alkali metal elements, alkaline earth metal elements, IIIA group elements, IVA group elements, transition metals and rare earth elements;
wherein x, y, m, n, t, a, s and d are mole fractions, x is more than 0, y is more than or equal to 0.01 and less than or equal to 0.10, m is more than 0, n is more than or equal to 0.2 and less than or equal to 0.4, t is more than or equal to 0 and less than or equal to 0.02, a is more than or equal to 1.01 and less than or equal to 1.07, s is more than or equal to 1.01 and less than or equal to 1.07, 1-x-y is more than or equal to 0.80 and less than or equal to 0.96, 1-m-n-t is more than or equal to.
The second aspect of the present invention provides a method for preparing the positive active material for a lithium battery, comprising the steps of:
step 1, nuclear precursor preparation: preparing a first mixed aqueous solution of a Ni source compound, a Co source compound and an M1 source compound, mixing the first mixed aqueous solution, a carbonate solution and ammonia water, and reacting under an alkaline condition to obtain a nuclear precursor Ni1-x-yCoxM1yCO3(ii) a Wherein M1 is selected from Mn and/or Al; x and y are mole fractions, x>0，0.01≤y≤0.10，0.60≤1-x-y≤0.96；
And step 3, sintering: mixing and grinding the precursor with the core-shell structure obtained in the step 2, a lithium source and a water-soluble sintering aid, uniformly grinding, sintering, and cooling and annealing after sintering to obtain a target product with a core-shell structure, wherein the chemical formula of the target product is as follows:
[Lia(Ni1-x-yCoxM1y)O2]d·[Lis(Ni1-m-n-tComM2nM4t)O2]1-d (I)
Lia(Ni1-x-yCoxM1y)O2is a chemical formula of a core of the positive active material for a lithium battery, Lis(Ni1-m-n-tComM2nM4t)O2Is a chemical formula of a shell of the positive active material for a lithium battery; the M2 is selected from Mn and/or Al; the M4 is selected from one or more of alkali metal elements, alkaline earth metal elements, IIIA group elements, IVA group elements, transition metals and rare earth elements; wherein M4 is at least one selected from Mg, Zr, Al, Sc, Ti, W, Sr, Nb, Si, Y, La, Ta, Cs, Ce, Ga, Sn, Er, V, Sm and Mo; m, n, t, s and d are mole fractions, m>0，0.2≤n≤0.4，0≤t≤0.02，0.30≤1-m-n-t≤0.70，1.01≤s≤1.07，0.70≤d≤1。
A third aspect of the invention provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, the positive electrode containing the positive electrode active material for a lithium battery as described above.
In order to make the aforementioned and other objects, features and advantages of the invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.
In one aspect, the present invention provides a positive active material for a lithium battery having a chemical formula as shown in formula (I):
[Lia(Ni1-x-yCoxM1y)O2]d·[Lis(Ni1-m-n-tComM2nM4t)O2]1-d (I)
in some embodiments, the chemical formula of the core of the positive active material for a lithium battery is Lia(Ni1-x- yCoxM1y)O2The chemical formula of the shell of the positive active material for a lithium battery is Lis(Ni1-m-n-tComM2nM4t)O2. Wherein M1 and M2 are each independently selected from Mn and/or Al; the M4 is selected from one or more of alkali metal elements, alkaline earth metal elements, IIIA group elements, IVA group elements, transition metals and rare earth elements.
As an embodiment, M1 is selected from Mn and Al, M2 is selected from Mn; the chemical formula of the core is Lia(Ni1-x-yCoxAl1- yMny)O2(ii) a The chemical formula of the shell is Lis(Ni1-m-n-tComMnnM4t)O2；
As an embodiment, M1 is selected from Mn and Al, M2 is selected from Al; the chemical formula of the core is Lia(Ni1-x-yCoxAl1- yMny)O2The chemical formula of the shell is Lis(Ni1-m-n-tComAlnM4t)O2；
As an embodiment, M1 is selected from Mn and Al, M2 is selected from Mn and Al; the chemical formula of the core is Lia(Ni1-x- yCoxAl1-yMny)O2The chemical formula of the shell is Lis(Ni1-m-n-tComAl1-nMnnM4t)O2；
In one embodiment, M1 is selected from Al, M2 is selected from Mn; the chemical formula of the core is Lia(Ni1-x-yCoxAly)O2The chemical formula of the shell is Lis(Ni1-m-n-tComMnnM4t)O2；
AsIn one embodiment, M1 is selected from Al, M2 is selected from Al; the chemical formula of the core is Lia(Ni1-x-yCoxAly)O2The chemical formula of the shell is Lis(Ni1-m-n-tComAlnM4t)O2；
As an embodiment, M1 is selected from Al, M2 is selected from Mn and Al; the chemical formula of the core is Lia(Ni1-x-yCoxAly)O2The chemical formula of the shell is Lis(Ni1-m-n-tComAl1-nMnnM4t)O2；
As an embodiment, M1 is selected from Mn, M2 is selected from Mn; the chemical formula of the core is Lia(Ni1-x-yCoxMny)O2The chemical formula of the shell is Lis(Ni1-m-n-tComMnnM4t)O2；
As an embodiment, M1 is selected from Mn, M2 is selected from Al; the chemical formula of the core is Lia(Ni1-x-yCoxMny)O2The chemical formula of the shell is Lis(Ni1-m-n-tComAlnM4t)O2；
As an embodiment, M1 is selected from Mn, M2 is selected from Al and Mn; the chemical formula of the core is Lia(Ni1-x-yCoxMny)O2The chemical formula of the shell is Lis(Ni1-m-n-tComAl1-nMnnM4t)O2。
In some embodiments, the Mn may be derived from one or more of manganese sulfate, manganese acetate, manganese chloride, manganese nitrate; the Al may be derived from one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum trichloride, aluminum acetate, aluminum isopropoxide, aluminum n-propoxide, aluminum sulfate, aluminum nitrate.
In some embodiments, the shell of the positive active material for a lithium battery has a layered or spinel structure. As one embodiment, the layered positive active material for a lithium battery includes one or more of lithium nickel cobalt manganese oxide, lithium rich lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium cobalt oxide, lithium nickel cobalt oxide, and lithium manganese oxide. As one embodiment, the spinel is used for a positive active material of a lithium battery including lithium manganate and/or lithium nickel manganate.
In the embodiment of the invention, x, y, m, n, t, a, s, b and d are mole fractions, x is more than 0, y is more than or equal to 0.01 and less than or equal to 0.10, m is more than or equal to 0, n is more than or equal to 0.2 and less than or equal to 0.4, t is more than or equal to 0 and less than or equal to 0.02, a is more than or equal to 1.01 and less than or equal to 1.07, s is more than or equal to 1.01 and less than or equal to 1.07, 1-x-y is more than or equal to 0.60 and less than or equal to 0.96, 1-m-n-t is more than or equal to 0.30 and less than or equal to 0.70 and less than or equal to 1.
In some embodiments, x>0，0.01≤y≤0.05，m>0，0.2≤n≤0.3，0<t≤0.02，1.015≤a≤1.06，0<b is less than or equal to 0.02, s is less than or equal to 1.015 and less than or equal to 1.06, 1-x-y is less than or equal to 0.80 and less than or equal to 0.92, 1-m-n-t is less than or equal to 0.34 and less than or equal to 0.60, and d is more than or equal to 0.70 and less than or equal to 0.85. In some embodiments, the mole fraction of Ni content in the positive active material for a lithium battery (e.g., as in formula Li)a(Ni1-x-yCoxM1y)O21-x-y) of (a) may be at least 0.60, at least 0.61, at least 0.62, at least 0.63, at least 0.64, at least 0.65, at least 0.66, at least 0.67, at least 0.68, at least 0.69, at least 0.70, at least 0.71, at least 0.75, at least 0.80, at least 0.81, at least 0.82, at least 0.83, at least 0.85, at least 0.86, at least 0.88, at least 0.89, at least 0.90, at least 0.91, at least 0.92, at least 0.93, at least 0.94, at least 0.95, at least 0.951, at least 0.953, at least 0.955, at least 0.957, at least 0.96, and/or not more than 0.96, not more than 0.957, not more than 0.955, not more than 0.953, not more than 0.951, not more than 0.95, not more than 0.94, not more than 0.93, not more than 0.90, not more than 0.81, not more than 0.80, not more than 0.70, not more than 0.80, not, A mole fraction of no greater than 0.70, no greater than 0.69, no greater than 0.68, no greater than 0.67, no greater than 0.66, no greater than 0.65, no greater than 0.64, no greater than 0.63, no greater than 0.62, no greater than 0.61, no greater than 0.60, and the like.
In some embodiments, the molar fraction of Li content in the positive active material core for a lithium battery (e.g., asFormula Lia(Ni1-x-yCoxM1y)O2A) of (a) can be present in a mole fraction of at least 1.01, at least 1.02, at least 1.03, at least 1.035, at least 1.04, at least 1.045, at least 1.05, at least 1.055, at least 1.06, at least 1.065, at least 1.07, and/or not more than 1.07, not more than 1.065, not more than 1.06, not more than 1.055, not more than 1.05, not more than 1.045, not more than 1.04, not more than 1.035, not more than 1.03, not more than 1.02, not more than 1.01, and the like.
Here, when a is less than 1, the content of Li is insufficient, which may affect Li+The lithium removal or insertion can reduce the charge and discharge capacity of the positive active material for the lithium battery, the content of Li is too high, more byproducts are generated in the preparation process, and the obtained positive active material for the lithium battery can contain LiOH and Li2CO3When alkaline substances are left, the alkaline substances on the surface are easy to attack the binder in the positive electrode glue solution, the binder forms double bonds to generate adhesion, slurry jelly is caused, the coating effect is influenced, and the performance of the battery cell is influenced. According to the embodiment of the invention, the molar fraction of the Li content is 1.01-1.07, the charge and discharge capacity is high, the byproducts are few, the improvement of the battery cell performance is facilitated, and the unexpected effect is achieved.
In some embodiments, the positive active material structure for a lithium battery has an average particle diameter D50 of 3 to 5 μm and an average particle diameter D50 of 2.5 to 4 μm; the positive active material for a lithium battery has a tap density of 1.9 to 2.4g/cm3. In some embodiments, the positive active material for a lithium battery is a primary particle. In some cases, it may also be present as secondary particles of the positive active material for a lithium battery. The positive active material for the lithium battery has a core-shell structure, and can effectively inhibit the corrosion of electrolyte on a body material and the dissolution of metal ions, so that more lithium vacancies of the active material are kept, and the cycling stability of the material is improved.
In some embodiments, the tap density of the positive active material for a lithium battery may be at least 1.5g/cm3At least 1.6g/cm3At least 1.7g/cm3At least 1.8g/cm3At least 1.9 g-cm3At least 2.0g/cm3At least 2.1g/cm3At least 2.2g/cm3At least 2.3g/cm3At least 2.4g/cm3And/or not more than 2.4g/cm3Not more than 2.3g/cm3Not more than 2.2g/cm3Not more than 2.1g/cm3Not more than 2.0g/cm3Not more than 1.9g/cm3Not more than 1.8g/cm3Not more than 1.7g/cm3Not more than 1.6g/cm3Not more than 1.5g/cm3Etc. are present.
In some cases, the thickness of the shell of the positive active material for a lithium battery is 0.05 to 1.1 μm; in some cases, the shell thickness is less than 1.1 μm, less than 1.05 μm, less than 1.0 μm, less than 0.95 μm, less than 0.9 μm, less than 0.8 μm, less than 0.7 μm, less than 0.6 μm, less than 0.5 μm, less than 0.4 μm, less than 0.3 μm, less than 0.2 μm, less than 0.1 μm, less than 0.08 μm, less than 0.06 μm, less than 0.05 μm; in some cases, the shell thickness can be at least 0.05 μm, at least 0.06 μm, at least 0.08 μm, at least 0.1 μm, at least 0.2 μm, at least 0.3 μm, at least 0.4 μm, at least 0.5 μm, at least 0.6 μm, at least 0.7 μm, at least 0.8 μm, at least 0.9 μm, at least 0.95 μm, at least 1.0 μm, at least 1.05 μm, at least 1.1 μm, and the like. In various embodiments, any combination of these is also possible; for example: the shell thickness may be between 0.05 μm and 1.1 μm. In addition, it should be understood that the shell may be uniformly or non-uniformly distributed around the core.
The thickness of the shell has a great influence on the performance of the core-shell structure composition, and if the thickness of the shell is too thin, the shell is easily corroded by electrolyte to expose the core, so that the stability of the composition is influenced; conversely, if the shell is too thick, the capacity of the composition will be reduced. The composition provided by the embodiment of the invention has proper shell thickness, can balance the stability of the composition and the capacity of the composition, and has optimal stability and capacity.
In another aspect, an embodiment of the present invention further provides a method for preparing a positive active material for a lithium battery, including the steps of:
step 1, nuclear precursor preparation: preparation of Ni Source CompoundThe method comprises the steps of mixing a first mixed aqueous solution of a Co source compound and an M1 source compound, a carbonate solution and ammonia water, and reacting under an alkaline condition to obtain a nuclear precursor Ni1-x-yCoxM1yCO3(ii) a Wherein x and y are mole fractions, and x>0，0.01≤y≤0.10，0.60≤1-x-y≤0.96；
In embodiments of the invention, M1 is selected from Mn and/or Al. The reaction conditions include: the pH value is 9-12, the reaction temperature is 60-90 ℃, the reaction time is 3-12h under the constant temperature, and the cooling temperature is 25-30 ℃.
In the embodiment of the invention, the M2 is selected from Mn and/or Al; the M4 is selected from one or more of alkali metal elements, alkaline earth metal elements, IIIA group elements, IVA group elements, transition metals and rare earth elements; the M4 is at least one selected from Mg, Zr, Al, Sc, Ti, W, Sr, Nb, Si, Y, La, Ta, Cs, Ce, Ga, Sn, Er, V, Sm and Mo. The reaction conditions include: the pH value is 10-12, and the reaction temperature is 60-65 ℃.
In some embodiments, in steps 1 and 2, the reaction may be carried out in the presence of a dispersant, which may use one or more mixtures of surfactants, polyvinyl alcohols, polyglycerols. In some cases, the surfactant may be exemplified by cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG-400), Span-80 (Span-80), and polyoxyethylene octylphenol ether-10 (op-10), and the like.
In the present invention, the above-mentioned surfactants may be used alone or in combination of two or more, and may be used in combination with other dispersants. In the embodiment of the invention, the addition of the surfactant realizes the effect that a common surfactant such as Cetyl Trimethyl Ammonium Bromide (CTAB) is beneficial to particle dispersion and uniform particle distribution, and can regulate and control the growth direction and the dispersibility of crystals, regulate the crystal morphology, influence the layered structure of the material and enable the crystal structure to grow and have uniform particle size.
The mixed salt solution and the alkali liquor are added into the reaction kettle dispersed with the surfactant in a parallel flow manner, so that a large number of crystal nuclei are formed, when metal ions and the precipitant are continuously added, the metal ions and the precipitant are rapidly dispersed in the solution containing the surfactant under the stirring action, the concentrations of the precipitant and the metal ions in the reaction system are low, the supersaturation degree in the solution is low, new crystal nuclei are formed, the crystal particles grow gradually and the particle morphology is regulated, and the particle size of the positive electrode active material for the lithium battery obtained by metal ion parallel flow feeding is relatively uniformly distributed.
In some embodiments, the Ni source compound is derived from one or more mixtures of nickel chloride, nickel sulfate, nickel acetate, nickel nitrate, or crystalline water compounds thereof; in some embodiments, the Co source compound is derived from one or more mixtures of cobalt sulfate, cobalt acetate, cobalt chloride, cobalt nitrate, or crystalline water compounds thereof.
According to the invention, a Ni source compound, a Co source compound, a Mn source compound and/or an Al source compound are prepared into a solution, a nickel salt, a cobalt salt, an aluminum salt and a manganese salt can be uniformly distributed in the solution, and the positive active material for the lithium battery is prepared by adopting the solution in which the nickel salt, the cobalt salt, the aluminum salt and the manganese salt are uniformly distributed. The precipitation equilibrium constants Ksp of Ni, Co, Al and Mn are different, so that the precipitation order of Ni, Co, Al and Mn in a solution can be influenced.
And step 3, sintering: mixing and grinding the precursor with the core-shell structure obtained in the step 2, a lithium source and a water-soluble sintering aid, uniformly grinding, sintering, and cooling and annealing after sintering to obtain the anode active material with the core-shell structure for the lithium battery, wherein the chemical formula of the anode active material for the lithium battery is shown as a formula (I):
[Lia(Ni1-x-yCoxM1y)O2]d·[Lis(Ni1-m-n-tComM2nM4t)O2]1-d (I)
Lia(Ni1-x-yCoxM1y)O2is a chemical formula of a core of the positive active material for a lithium battery, Lis(Ni1-m-n-tComM2nM4t)O2Is a chemical formula of a shell of the positive active material for a lithium battery; wherein M4 is selected from one or more of alkali metal elements, alkaline earth metal elements, IIIA group elements, IVA group elements, transition metals and rare earth elements; wherein s, t and d are mole fractions, s is more than or equal to 1.01 and less than or equal to 1.07, t is more than or equal to 0 and less than or equal to 0.02, and d is more than or equal to 0.70 and less than or equal to 1.
In one embodiment, when t is 0, the product obtained in the step 3 reaction is [ Li ═ Lia(Ni1-x-yCoxM1y)O2]d·[LisNi1-m-nComM2nO2]1-d。
In one embodiment, when t is 0 and d is 1, the product obtained from the reaction in step 4 is Lia(Ni1-x- yCoxM1y)O2。
In the embodiment of the invention, the sintering is carried out for 8-20 hours by adding a lithium source and a water-soluble auxiliary agent at 780-900 ℃ in the air or oxygen atmosphere.
When the sintering temperature is less than 700 ℃, lithiation is insufficient, whereas when the sintering temperature exceeds 1000 ℃, oxidation of metal ions is inhibited, and charge-discharge cycle durability and initial capacity are reduced. The sintering temperature is preferably 780 to 900 ℃. Sintering may be performed in multiple stages.
As the lithium source, one or more of lithium carbonate, lithium hydroxide, lithium acetate, and lithium oxalate can be used. When lithium carbonate is used as the lithium source, for example, the cost is lower than when lithium hydroxide is used. One or more of water-soluble sulfate and water-soluble chloride can be used as the water-soluble sintering aid, and the addition of the water-soluble sintering aid can further reduce the sintering temperature and avoid the influence of high-temperature sintering on the particle morphology and the performance of the high-nickel material.
In some embodiments, different temperature-reducing annealing treatments may also produce different effects. Furnace cooling, staged rate cooling or rate cooling can be adopted, as an implementation mode, the cooling rate of the rate cooling is 0.01-3.0 ℃/min; as an embodiment, the cooling rate is 0.02-2.5 ℃/min; as an embodiment, the cooling rate is 0.02-1.0 deg.C/min. The composition is of a core-shell structure, and in the cooling process, if the temperature is rapidly reduced and the temperature difference change is too large, the crystallization stress of the core and the shell is inconsistent, and the stress is distorted, the shell is cracked, and the core-shell structure cannot be formed; the core-shell structure is formed by adopting rate cooling, staged rate cooling or furnace cooling, the cooling rate is slow, and the contraction ratio of the core and the shell can be effectively prevented from being inconsistent; meanwhile, the annealing process eliminates oxygen defects formed by local overburning of the material in the sintering process, so that the obtained material has higher crystallinity and better structural stability. Therefore, the high-nickel core-shell structure cathode material obtained by the preparation method has high structural stability and long cycle life.
In some embodiments, the method further comprises a second sintering: and cleaning the sintered product, mixing the cleaned product with a water-soluble sintering aid and a coating material, grinding, and sintering.
In some embodiments, the cleaning means is flushed with a stream of carbon dioxide gas; in some embodiments, the washing means is washing with carbonated water. The residual alkali on the surface of the positive active material cleaned by carbon dioxide airflow or carbonated water is effectively reduced, the attack of alkaline substances on the surface of the positive active material on the binder in the positive glue solution in the preparation process of the positive active material is reduced, the double bonds formed by the binder are avoided, the coating effect is improved, and the performance of a battery cell is improved.
In some embodiments, M4 is selected from one or more of alkali metal elements, alkaline earth metal elements, group IIIA elements, group IVA elements, transition metals, and rare earth elements.
In one embodiment, M4 is at least one selected from the group consisting of Mg, Zr, Al, Sc, Ti, W, Sr, Nb, Si, Y, La, Ta, Cs, Ce, Ga, Sn, Er, V, Sm, and Mo. In some cases, M4 is derived from one or more of an oxide of metal M4, a hydroxide of metal M4, a chloride of metal M4, a sulfate of metal M4, a nitrate of metal M4, a fluoride of metal M4, a sulfide of metal M4, a telluride of metal M4, a selenide of metal M4, an antimonide of metal M4, a phosphide of metal M4, and a complex oxide of metal M4. In one embodiment, Mg is derived from one or more of magnesium hydroxide, magnesium chloride, magnesium sulfate, magnesium carbonate, and magnesium nitrate.
According to the technical scheme, different metal elements are coated on the surfaces of the core and/or the shell of the positive active material for the lithium battery, and the influence on the structure and the size of the unit cell is different, so that the influence on the multiplying power and the specific capacity of the material is different, and the alkali metal elements and the alkaline earth metal elements have structures which are beneficial to the stability of a laminated structure, so that the crystal structure is smoother, the collapse of the unit cell in the circulating process is prevented, the capacity density is improved, and the capacity and the multiplying power of the positive active material for the lithium battery are improved.
According to the method, a metal source compound and a dispersing agent are used for coprecipitation to obtain a single crystal precursor, then the single crystal precursor is mixed with a lithium source and a water-soluble auxiliary agent, the mixture is ground and sintered to obtain a single crystal anode material, wherein the single crystal precursor is of a core-shell structure, and the finally prepared anode material is single-crystal in shape and has a core-shell structure.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
Fig. 2 is a schematic view of a process of forming a positive active material for a lithium battery according to one embodiment of the present invention.
Detailed Description
To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description of the embodiments, structures, features and effects according to the present invention will be made with reference to the accompanying drawings and preferred embodiments.
The positive active material for a lithium battery according to the present invention will be described in detail with reference to examples.
Example 1
A positive active material for a lithium battery, which is a primary particle having a structural formula of:
[Li1.06(Ni0.83Co0.07Al0.05Mn0.05)O2]0.95·[Li1.02(Ni0.55Co0.05Al0.4)O2]0.05
Li1.06(Ni0.83Co0.07Al0.05Mn0.05)O2a chemical formula of a core of the positive active material for a lithium battery, Li1.02(Ni0.55Co0.05Al0.4)CO3For the chemical formula of the shell of the positive active material for a lithium battery, the preparation method includes:
step 1, preparation of Nuclear precursor
According to the molar ratio of the elements Ni: co: al: mn 0.83:0.07:0.05
Calculating and weighing soluble nickel salt, soluble cobalt salt, soluble aluminum salt and soluble manganese salt; adding the two into deionized water together to mix and prepare a first mixed aqueous solution A with the concentration of 1 mol/L;
mixing the first mixed aqueous solution A, ammonia water, carbonate solution and a dispersing agent, controlling the pH to be 9, reacting at the constant temperature of 60 ℃ for 3 hours, cooling to 30 ℃, filtering, washing and drying precipitates to obtain Ni0.83Co0.07Al0.05Mn0.05CO3；
Dissolving Ni source, Co source and Al source in deionized water in proportion to obtain a second mixed aqueous solution, mixing with Ni0.83Co0.07Al0.05Mn0.05CO3Mixing ammonia water and NaOH solution, controlling the reaction temperature of the system at 60 ℃, controlling the stirring speed at 750 rpm, adjusting the pH of the mixed solution to 10, carrying out coprecipitation reaction for 3 hours, and filtering, washing and drying precipitates to obtain the composition.
Step 3, preparing the positive active material of the lithium battery with the core-shell structure
And (2) mixing the composition obtained by sintering in the step (2) with dried lithium carbonate and a water-soluble auxiliary agent in proportion, wherein the use amount of the lithium carbonate is that the molar ratio of Li in the lithium carbonate to (Ni + Co + Al) in a positive active material for a lithium battery is 0.86, the addition amount of the water-soluble sintering auxiliary agent is that the mass ratio of the positive active material for the lithium battery is 10%, uniformly mixing and grinding the mixture, sintering the mixture in an oxygen atmosphere, heating the mixture to 850 ℃ for reaction for 12 hours, and then cooling the mixture to room temperature along with a furnace to obtain a target product with a core-shell structure.
The structural formula of the target product is as follows:
[Li1.06(Ni0.83Co0.07Al0.05Mn0.05)O2]0.95·[Li1.02(Ni0.55Co0.05Al0.4)O2]0.05
ICP element analysis test results show that the mole percentage of each metal of Ni, Co, Al and Mn is as follows:
example 2
[Li1.05(Ni0.85Co0.08Al0.04Mn0.03)O2]0.93·[Li1.03(Ni0.58Co0.06Mn0.35Sc0.01)O2]0.07
the preparation process is similar to example 1, except that:
And dissolving a Ni source, a Co source, an Al source and a Sc source in deionized water according to a ratio (Ni: Co: Mn: Sc is 0.58:0.06:0.35:0.01) to obtain a second mixed aqueous solution, mixing the second mixed aqueous solution with the core precursor, ammonia water and a NaOH solution, and reacting to obtain the precursor with the core-shell structure.
The structural formula of the target product in this example 2 is:
[Li1.05(Ni0.85Co0.08Al0.04Mn0.03)O2]0.93·[Li1.03(Ni0.58Co0.06Mn0.35Sc0.01)O2]0.07
ICP element analysis test results show that the mole percentages of Ni, Co, Al, Mn and Sc are as follows:
example 3
Embodiment 3 of the present invention provides a positive electrode active material for a lithium battery doped with a V-shell, having a structural formula:
[Li1.07(Ni0.86Co0.08Al0.03Mn0.03O2]0.9·[Li1.05(Ni0.53Co0.15Al0.1Mn0.2V0.02)O2]0.1
the preparation process is similar to example 2.
The target product of this example 3 has the formula:
[Li1.07(Ni0.86Co0.08Al0.03Mn0.03O2]0.9·[Li1.05(Ni0.53Co0.15Al0.1Mn0.2V0.02)O2]0.1
ICP element analysis test results show that the mole percentage of each metal of Ni, Co, Al, Mn and V is as follows:
example 4
This example 4 adopts a Ti-doped positive active material for a lithium battery, and the structural formula is:
[Li1.035(Ni0.88Co0.08Al0.04)O2]0.88·[Li1.01(Ni0.52Co0.165Al0.3Ti0.015)O2]0.12
ICP element analysis test results show that the mole percentage of each metal of Ni, Co, Al and Ti is as follows:
example 5
This example 5 provides a positive active material for a lithium battery doped with Sm shell, the structural formula of which is:
[Li1.02(Ni0.90Co0.08Al0.02O2]0.85·[Li1.015(Ni0.34Co0.25Mn0.4Sm0.01)O2]0.15
the ICP element analysis test result shows that the mole percentages of the metals of Ni, Co, Al, Mn and Sm are as follows:
example 6
This example 6 provides a Mo-doped positive active material for a lithium battery, having a structural formula:
[Li1.025(Ni0.91Co0.05Al0.04O2]0.82·[Li1.03(Ni0.45Co0.13Al0.1Mn0.3Mo0.02)O2]0.18
the ICP element analysis test result shows that the mole percentages of the metals of Ni, Co, Al, Mn and Mo are as follows:
example 7
This example 7 provides a positive active material for a lithium battery doped with Ta, having a structural formula:
[Li1.055(Ni0.92Co0.04Mn0.04)O2]0.8·[Li1.02(Ni0.5Co0.14Al0.35Ta0.01)O2]0.2
ICP element analysis test results show that the mole percentages of Ni, Co, Al, Mn and Ta are as follows:
example 8
This example 8 provides a positive active material for a lithium battery doped with Mg, having a structural formula:
[Li1.04(Ni0.93Co0.02Mn0.05O2]0.75·[Li1.05(Ni0.6Co0.08Mn0.3Mg0.02)O2]0.25
ICP element analysis test results show that the mole percentage of each metal of Ni, Co, Mn and Mg is as follows:
example 9
This example 9 provides a positive active material for a lithium battery doped with Nb, which has a structural formula:
[Li1.01(Ni0.95Co0.02Mn0.03)O2]0.7·[Li1.03(Ni0.7Co0.08Al0.1Mn0.1Nb0.02)O2]0.3
ICP element analysis test results show that the mole percentages of Ni, Co, Al, Mn and Nb are as follows:
example 10
The positive active material for a lithium battery provided in this example 10 has the structural formula:
[Li1.06(Ni0.60Co0.30Al0.05Mn0.05)O2]0.95·[Li1.02(Ni0.34Co0.33Mn0.33)O2]0.05
ICP element analysis test results show that the mole percentage of each metal of Ni, Co, Al and Mn is as follows:
example 11
The positive active material for a lithium battery provided in example 11 has a structural formula as follows:
[Li1.06(Ni0.63Co0.27Al0.05Mn0.05)O2]0.95·[Li1.02(Ni0.34Co0.33Mn0.33)O2]0.05
ICP element analysis test results show that the mole percentage of each metal of Ni, Co, Al and Mn is as follows:
example 12
The positive active material for a lithium battery provided in example 12 has the structural formula:
[Li1.06(Ni0.64Co0.26Al0.05Mn0.05)O2]0.95·[Li1.02(Ni0.34Co0.33Mn0.33)O2]0.05
ICP element analysis test results show that the mole percentage of each metal of Ni, Co, Al and Mn is as follows:
examples 4 to 14 are similar to the preparation methods of examples 1 to 3, except that: the reaction conditions, raw material ratios and products of each step are shown in tables 1 and 2.
Example 15
A positive active material for a lithium battery, which is a primary particle, has a structural formula of:
Li1.06(Ni0.64Co0.26Al0.05Mn0.05)O2the preparation method comprises the following steps:
step 1, precursor Ni0.64Co0.26Al0.05Mn0.05CO3Preparation of
According to the molar ratio of the elements of Ni, Co, Al and Mn being 0.64, 0.26, 0.05 and 0.05
Calculating and weighing soluble nickel salt, soluble cobalt salt, soluble aluminum salt and soluble manganese salt; adding the two into deionized water together to mix and prepare a first mixed aqueous solution A with the concentration of 1 mol/L;
mixing the first mixed aqueous solution A, ammonia water, carbonate solution and a dispersing agent, controlling the pH to be 9, reacting at the constant temperature of 60 ℃ for 3 hours, cooling to 30 ℃, filtering, washing and drying precipitates to obtain Ni0.64Co0.26Al0.05Mn0.05CO3；
And (3) sintering: drying lithium carbonate until crystal water is completely lost, and mixing with the Ni prepared in the step 10.64Co0.26Al0.05Mn0.05CO3Mixing the water-soluble sintering aid in proportion, wherein the use amount of lithium carbonate is that the molar ratio of Li in lithium carbonate to (Ni + Co + Al + Mn) in the composition is 0.86, the addition amount of the water-soluble sintering aid is that the mass ratio of the composition is 10%, uniformly mixing and grinding, sintering in an oxygen atmosphere, heating to 820 ℃, reacting for 16 hours, and then cooling to room temperature at a cooling rate of 0.3 ℃/min; obtaining a target product Li1.06(Ni0.64Co0.26Al0.05Mn0.05)O2。
Example 16
A positive active material for a lithium battery, which is a primary particle, has a structural formula of: li1.01(Ni0.70Co0.20Al0.10)O2The preparation process is analogous to example 15.
Example 17
A positive active material for a lithium battery, which is a primary particle, has a structural formula of: li1.03(Ni0.88Co0.08Mn0.04)O2The preparation process is analogous to example 15.
Example 18
A positive active material for a lithium battery, which is a primary particle, has a structural formula of: li1.04(Ni0.93Co0.02Al0.205Mn0.025)O2The preparation process is analogous to example 15.
Comparative example 1
Comparative example 1 provides a ternary cathode active material of the formula Li1.035Ni0.815Co0.15Al0.035O2The preparation method comprises the following steps:
step (1), primary sintering: precursor Ni of ternary positive electrode active material1-x-yCoxAly(OH)2+ySintering, heating to 500 ℃ and reacting for 10 hours;
step (2), sintering for the second time: drying lithium hydroxide monohydrate until crystal water is completely lost, mixing the lithium hydroxide monohydrate with the sintered product obtained in the step (1), wherein the use amount of the lithium hydroxide monohydrate is that the molar ratio of Li in the lithium hydroxide monohydrate to (Ni + Co + Al) in a ternary positive electrode active material precursor is 1.035:1, uniformly mixing and grinding, sintering in an oxygen atmosphere, heating to 715 ℃ for reaction for 16.5 hours, and then cooling to room temperature at a cooling rate of 0.3 ℃/min;
step (3), sintering for the third time: heating the sintered product obtained in the step (2) to 650 ℃, sintering for 3.5 hours, and cooling to room temperature to obtain the comparative material Li1.035Ni0.815Co0.15Al0.035O2。
Table 1, examples 1 to 18 and comparative example 1 reaction conditions in the respective steps
Table 2, examples 1 to 18 and comparative example 1 Each step reaction conditions and products
Assembling a CR2032 button battery:
the positive active material for the lithium battery prepared in the embodiments 1 to 18 and the positive active material prepared in the comparative example 1 are used as active materials of a positive electrode, a metal lithium sheet is used as a negative electrode, a Celgard 2500 diaphragm is used as the diaphragm, the electrolyte is fosai LB-002 electrolyte of Suzhou Buddhist New Material Co., Ltd, a CR2032 type button battery is assembled according to the prior art, and the assembling sequence is as follows: the positive cover is flatly placed, the spring piece is placed, the stainless steel sheet is placed, the positive plate is placed, the electrolyte is injected, the diaphragm sheet is placed, the lithium sheet is placed, the negative cap is covered, the sealing is carried out, and the assembly is completed. The cell was assembled in a dry glove box filled with argon. After the assembly was completed, the cell was subjected to performance testing, the test results of which are shown in table 3.
1. ICP elemental detection
The test method comprises the following steps: inductively coupled plasma mass spectrometry test method
Inductively coupled plasma mass spectrometer
The model is as follows: prodigy DC Arc
Test instrument manufacturers: leisha Leibos company, Rieman
2. Resistivity of powder
The test method comprises the following steps: four-probe method
The instrument name: powder resistance tester
The instrument model is as follows: MCP-T700
The instrument manufacturer: mitsubishi chemical
3. Cycle performance
Name of the test instrument: xinwei battery detection system, model: BTS-5V10mA
Test instrument manufacturers: shenzhen, New Wille electronics, Inc.;
the test method comprises the following steps: charging to 4.3V at a constant current of 1C at 25 ℃, keeping the constant voltage of 4.3V to 0.05C, then discharging to 3V at 1C, repeatedly carrying out 100 times of the charge-discharge cycles, measuring the discharge capacity at the first cycle and the discharge capacity at the 100 th cycle, and calculating the capacity retention rate after 100 cycles, wherein the formula is as follows: capacity retention after cycling ═ 100% of (discharge capacity at 100 th cycle)/(discharge capacity at first cycle).
4. Tap density
Name of the test instrument: tap density instrument
The instrument model is as follows: JZ-1
The instrument manufacturer: chengdu refined powder test equipment Co Ltd
The test method comprises the following steps: about 10 to 20g of the positive electrode active material for a lithium battery was weighed with an accuracy of 0.0001 g. The positive active material for a lithium battery is put into a measuring cylinder, and then the measuring cylinder is fixed on a support. The positive active material for a lithium battery was repeatedly tapped (i.e., automatically lifted and dropped into a measuring cylinder) 3000 times, and then the corresponding volume was measured. Tap density is the mass after tapping/volume after tapping. Three replicates were performed and the results listed in table 2 represent the average of the three experiments.
5. The surface residual alkali amount test method comprises the following steps: acid-base titration method
(1) Preparation of positive active material for lithium battery clear solution: w was weighed with an accuracy of 0.0001g1(30.0000. + -. 0.0040g) of a positive electrode active material for lithium battery, W was weighed with an accuracy of 0.01g2(100 +/-0.1 g) deionized water, mixing a positive electrode active material for a lithium battery with the deionized water, replacing air in the mixed solution with argon, stirring, filtering to obtain a filtrate, transferring 50mL of the filtrate, putting the filtrate into a 100mL beaker, and preparing for titration;
(2) measurement of LiOH content: using phenolphthalein as an indicator, titrating with 0.05mol/L hydrochloric acid standard solution, and measuring the volume V of the consumed hydrochloric acid standard solution at the end point1；
(3) Measurement of Li2CO3The content is as follows: replacing CO in the titrated clear liquid in the step (2) by argon2Then titrating with 0.05mol/L hydrochloric acid standard solution by using methyl red indicator, and titrating the hydrochloric acid standard solution consumed at the end pointVolume V2；
LiOH content (wt%) calculation formula: omega1＝(2V1-V2)*0.05*2.395*W2/W1/50；
Li2CO3Content (wt%) calculation formula: omega2＝(V2-V1)*0.05*7.389*W2/W1/50；
2.395: the mass of LiOH in g corresponding to the hydrochloric acid standard solution (1.000 mol/L);
7.389: li in g equivalent to hydrochloric acid standard solution (2.000mol/L)2CO3The mass of (c);
surface residual alkali content omega of positive active material for lithium battery1+ω2。
Table 3, examples 1-18 and comparative example 1 Performance test results
Referring to tables 1 to 3 together, it can be seen that:
compared with the comparative example 1, the positive active material of the core-shell structure in the example 1 has the capacity retention rate of 95.2% and the surface residual alkali content of 0.32% after being cycled for 100 cycles, and the positive active material of the comparative example 1 has the capacity retention rate of 79.7% and the surface residual alkali content of 0.83% after being cycled for 100 cycles, so that compared with the comparative example 1, the positive active material of the core-shell structure in the example 1 has more stable cycling performance and reduced surface residual alkali content.
Compared with the comparative example 1, the positive active material doped with the Sc shell in the example 2 has the capacity retention rate of 101.2% and the surface residual alkali content of 0.38% after being cycled for 100 circles, the positive active material in the comparative example 1 has the capacity retention rate of 79.7% and the surface residual alkali content of 0.83% after being cycled for 100 circles, and compared with the comparative example 1, the positive active material doped with the Sc shell in the example 2 has more stable cycling performance and reduced surface residual alkali content.
Compared with the comparative example 1, the positive active material obtained by doping the V shell and cleaning the positive active material by using carbon dioxide gas flow in the embodiment 3 has the capacity retention rate of 106% after being cycled for 100 circles, the surface residual alkali content of 0.04% by weight, the positive active material in the comparative example 1 has the capacity retention rate of 79.7% after being cycled for 100 circles, and the surface residual alkali content of 0.83% by weight, and compared with the comparative example 1, the positive active material in the embodiment 3 doped with the V shell has more stable cycling performance; and the carbon dioxide airflow is adopted for cleaning, so that the residual alkali on the surface is effectively reduced.
Example 4 compared with comparative example 1, example 4 is a positive electrode active material obtained by doping with a Ti shell and washing with carbonated water, the capacity retention rate after 100 cycles is 99.5%, the weight percentage of surface residual alkali is 0.07%, the capacity retention rate after 100 cycles of the positive electrode active material of comparative example 1 is 79.7%, the weight percentage of surface residual alkali is 0.83%, and compared with comparative example 1, the positive electrode active material doped with a Ti shell of example 4 has more stable cycle performance; the residual alkali on the surface is effectively reduced by adopting carbonated water for cleaning.
Compared with the comparative example 1, the positive active material obtained by doping Sm shell and cleaning with carbon dioxide gas flow in the example 5 has the capacity retention rate of 96.7% and the surface residual alkali weight percentage of 0.11% after 100 cycles, the positive active material in the comparative example 1 has the capacity retention rate of 79.7% and the surface residual alkali weight percentage of 0.83% after 100 cycles, and compared with the comparative example 1, the positive active material doped with Sm shell in the example 5 has more stable cycle performance; and the carbon dioxide airflow is adopted for cleaning, so that the residual alkali on the surface is effectively reduced.
Compared with the comparative example 1, the positive active material obtained by doping the Mo shell and cleaning the positive active material by using carbon dioxide gas flow in the example 6 has the capacity retention rate of 102% and the surface residual alkali content of 0.12% after being cycled for 100 circles, the positive active material in the comparative example 1 has the capacity retention rate of 79.7% and the surface residual alkali content of 0.83% after being cycled for 100 circles, and compared with the comparative example 1, the positive active material doped by the Mo shell in the example 6 has more stable cycling performance; and the carbon dioxide airflow is adopted for cleaning, so that the residual alkali on the surface is effectively reduced.
Compared with the comparative example 1, the positive active material obtained by doping the Ta shell and washing the positive active material by using the carbonated water in the example 7 has the capacity retention rate of 102.6% and the surface residual alkali weight percentage of 0.14% after 100 cycles, the positive active material in the comparative example 1 has the capacity retention rate of 79.7% and the surface residual alkali weight percentage of 0.83% after 100 cycles, and compared with the comparative example 1, the positive active material doped by the Ta shell in the example 7 has more stable cycle performance; the residual alkali on the surface is effectively reduced by adopting carbonated water for cleaning.
Compared with the comparative example 1, the positive active material doped with the Mg shell in the example 8 has the capacity retention rate of 101.5% and the surface residual alkali content of 0.46% after 100 cycles, the positive active material in the comparative example 1 has the capacity retention rate of 79.7% and the surface residual alkali content of 0.83% after 100 cycles, and compared with the comparative example 1, the positive active material doped with the Mg shell in the example 8 has more stable cycle performance and reduced surface residual alkali content.
Example 9 compared with comparative example 1, example 9 is a positive electrode active material obtained by doping with Nb shells and washing with carbonated water, the capacity retention rate after 100 cycles is 101.8%, the weight percentage of surface residual alkali is 0.13%, the capacity retention rate after 100 cycles is 79.7%, the weight percentage of surface residual alkali is 0.83% of the positive electrode active material of comparative example 1, and compared with comparative example 1, the positive electrode active material doped with Nb shells of example 9 has more stable cycle performance; the residual alkali on the surface is effectively reduced by adopting carbonated water for cleaning.
Compared with the embodiment 3, the embodiment 3 is the positive active material obtained by doping the V shell and cleaning the positive active material by using the carbon dioxide gas flow, the capacity retention rate after 100 cycles is 106%, the weight percentage of the surface residual alkali is 0.04%, and the capacity retention rates after 100 cycles of the embodiments 10 to 14 are respectively 99.8%, 99.45%, 99.2% and 99.1%; compared with examples 10 to 14, example 3 is a positive electrode active material doped with a V shell, and can have a stable capacity retention rate while increasing the nickel content.
In summary, the positive electrode active material of the present invention has at least the following advantages:
(1) the positive active material of the invention has more stable cycle performance: compared with the comparative example 1, after the cycles of the examples 1 to 9 are 100 times, the capacity retention rate of the core-shell structure positive active material prepared by the embodiment of the invention is higher than that of the traditional ternary positive active material in the comparative example 1; compared with the traditional ternary cathode active material, the cathode active material has a core-shell structure, and can effectively inhibit the corrosion of electrolyte on a body material and the dissolution of metal ions, so that more lithium vacancies of the active material are kept, and the cycling stability of the material is improved;
(2) the positive active material prepared by shell doping has more stable cycle performance: compared with example 1, examples 2 and 5 are shell doped, and the capacity retention rates after 100 cycles of examples 2 and 5 are 101.2% and 96.7%, respectively, which are higher than those of example 1: shell doping is shown to improve cycling stability;
(3) the positive active material for the lithium battery is cleaned by carbon dioxide gas flow or carbonated water, so that the surface residual alkali amount is effectively reduced: compared with the unwashed positive active materials in the embodiments 1, 2 and 8 and the comparative example 1, the positive active materials in the embodiments 3 to 7 and 9 are washed by carbon dioxide airflow or carbonated water, and the residual alkali amount on the surface of the positive active material for the lithium battery washed by the carbon dioxide airflow or the carbonated water is effectively reduced, so that the attack of alkaline substances on the surface of the positive active material for the lithium battery on a binder in a positive glue solution in the process of preparing the positive active material for the lithium battery is reduced, the formation of double bonds by the binder is avoided, the coating effect is improved, and the performance of a battery cell is improved;
(4) the appropriate thickness of the shell in the core-shell structure can improve the stability and capacity of the positive active material for the lithium battery: the thickness of the positive active material shell for the lithium battery in the embodiment of the invention is 0.05-1.1 μm; if the thickness of the shell is too thin, the shell is easily corroded by an electrolyte to expose the core, which may affect the stability of a positive active material for a lithium battery; on the contrary, if the shell is too thick, the capacity of the positive active material for a lithium battery is reduced. The positive active material for a lithium battery provided by the embodiment of the invention has a proper shell thickness, can balance the stability of the positive active material for the lithium battery and the capacity of the positive active material for the lithium battery, and has optimal stability and capacity.
The embodiments of the present invention have been described in detail, but the embodiments are merely examples, and the present invention is not limited to the embodiments described above. Any equivalent modifications and substitutions to those skilled in the art are also within the scope of the present invention. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.
Claims (10)
1. A method for preparing a positive active material for a lithium battery, comprising the steps of:
step 1, nuclear precursor preparation: preparing a first mixed aqueous solution of a Ni source compound, a Co source compound and an M1 source compound, mixing the first mixed aqueous solution, a carbonate solution and ammonia water, and reacting under an alkaline condition to obtain a nuclear precursor Ni1-x-yCoxM1yCO3(ii) a Wherein M1 is selected from Mn and/or Al; x and y are mole fractions, x>0，0.01≤y≤0.10，0.60≤1-x-y≤0.96；
Step 2, preparing a shell precursor: preparing a second mixed aqueous solution of a Ni source compound, a Co source compound, a M2 source compound and a M4 source compound, and mixing the second mixed aqueous solution with the nuclear precursor Ni1-x-yCoxM1yCO3Mixing with ammonia water and NaOH solution, and precipitating a shell precursor Ni on the surface of the core precursor1-m-n-tComM2nM4t(OH)2Obtaining a precursor with a core-shell structure; wherein m, n and t are mole fractions, m>0，0.2≤n≤0.4，0≤t≤0.02，0.30≤1-m-n-t≤0.70。
And step 3, sintering: mixing and grinding the product obtained in the step 2, a lithium source and a water-soluble sintering aid, uniformly grinding, sintering, and cooling and annealing after sintering to obtain the target property right with a core-shell structure, wherein the chemical formula of the target property right is as follows:
[Lia(Ni1-x-yCoxM1y)O2]d·[Lis(Ni1-m-n-tComM2nM4t)O2]1-d
Lia(Ni1-x-yCoxM1y)O2is a chemical formula of a core of the positive active material for a lithium battery, Lis(Ni1-m-n- tComM2nM4t)O2Is a chemical formula of a shell of the positive active material for a lithium battery; the M2 is selected from Mn and/or Al; the M4 is selected from one or more of alkali metal elements, alkaline earth metal elements, IIIA group elements, IVA group elements, transition metals and rare earth elements; wherein M4 is at least one selected from Mg, Zr, Al, Sc, Ti, W, Sr, Nb, Si, Y, La, Ta, Cs, Ce, Ga, Sn, Er, V, Sm and Mo; m, n, t, a, s and d are mole fractions, m>0，0.2≤n≤0.4，0≤t≤0.02，0.30≤1-m-n-t≤0.70，1.015≤a≤1.06，1.01≤s≤1.07，0.70≤d≤1。
2. The method of claim 1, wherein the step 3 further comprises cleaning the sintered product, mixing the cleaned product with a water-soluble sintering aid, grinding the mixture, and sintering the mixture.
3. The method of preparing a positive active material for a lithium battery according to claim 1, wherein the steps 1 and 2 are carried out in the presence of a dispersant which is one or more of a surfactant, polyvinyl alcohol, and polyglycerin.
4. The method of preparing a positive active material for a lithium battery as claimed in claim 3, wherein the surfactant is span-80.
5. The method of claim 1, wherein the M4 is at least one selected from Sc, V, Ti, Sm, Mo, Ta, Mg, Nb.
6. The method of preparing a positive active material for a lithium battery as claimed in claim 1, wherein t ═ 0, and the positive active material for a lithium battery has a chemical formula of [ Li ═ 0a(Ni1-x-yCoxM1y)O2]d·[Lis(Ni1-m-nComM2n)O2]1-dA, x, y, s, m and n are mole fractions, a is more than or equal to 1.015 and less than or equal to 1.06, x>0，0.01≤y≤0.10，0.60≤1-x-y≤0.96，1.01≤s≤1.07，m>0，0.2≤n≤0.4，0.30≤1-m-n≤0.70，0.70≤d≤1。
7. The method of preparing a positive active material for a lithium battery according to claim 6, wherein: d-1, the chemical formula of the positive active material for a lithium battery is Lia(Ni1-x-yCoxM1y)O2A, x and y are mole fractions, a is more than or equal to 1.015 and less than or equal to 1.06, x>0，0.01≤y≤0.10，0.60≤1-x-y≤0.96。
8. The method of preparing a positive active material for a lithium battery according to claim 1, wherein: the surface residual alkali amount of the positive active material for a lithium battery is 0.04-0.45 wt%.
9. A lithium ion battery comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the positive electrode comprises a positive active material for a lithium battery prepared by the preparation method of any one of claims 1 to 9.
10. The lithium ion battery of claim 9, wherein: under the multiplying power of 1C, the capacity retention rate of the battery after 100 cycles is 94-106%.
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