JP7412883B2 - Positive electrode active material for lithium ion secondary battery and method for manufacturing the same - Google Patents
Positive electrode active material for lithium ion secondary battery and method for manufacturing the same Download PDFInfo
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- JP7412883B2 JP7412883B2 JP2018246679A JP2018246679A JP7412883B2 JP 7412883 B2 JP7412883 B2 JP 7412883B2 JP 2018246679 A JP2018246679 A JP 2018246679A JP 2018246679 A JP2018246679 A JP 2018246679A JP 7412883 B2 JP7412883 B2 JP 7412883B2
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- lithium
- positive electrode
- nickel composite
- composite oxide
- nickel
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- 239000007774 positive electrode material Substances 0.000 title claims description 60
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims description 43
- 229910001416 lithium ion Inorganic materials 0.000 title claims description 43
- 238000000034 method Methods 0.000 title claims description 19
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 171
- 239000002131 composite material Substances 0.000 claims description 101
- 229910052759 nickel Inorganic materials 0.000 claims description 77
- RSNHXDVSISOZOB-UHFFFAOYSA-N lithium nickel Chemical compound [Li].[Ni] RSNHXDVSISOZOB-UHFFFAOYSA-N 0.000 claims description 45
- 238000010304 firing Methods 0.000 claims description 33
- 239000000203 mixture Substances 0.000 claims description 31
- 229910052744 lithium Inorganic materials 0.000 claims description 29
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 229910052782 aluminium Inorganic materials 0.000 claims description 23
- 229910017052 cobalt Inorganic materials 0.000 claims description 21
- 239000010941 cobalt Substances 0.000 claims description 21
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 21
- 150000002642 lithium compounds Chemical class 0.000 claims description 21
- 239000000843 powder Substances 0.000 claims description 14
- 239000002994 raw material Substances 0.000 claims description 13
- 238000005406 washing Methods 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 12
- 239000002002 slurry Substances 0.000 claims description 11
- 239000012298 atmosphere Substances 0.000 claims description 9
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 238000002441 X-ray diffraction Methods 0.000 claims description 7
- 229910052720 vanadium Inorganic materials 0.000 claims description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- 229910052760 oxygen Inorganic materials 0.000 claims description 5
- 239000001301 oxygen Substances 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 238000003991 Rietveld refinement Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 229910017698 Ni 1-x-y Co Inorganic materials 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 2
- 150000002816 nickel compounds Chemical class 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 22
- 238000011156 evaluation Methods 0.000 description 20
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 16
- 229910052751 metal Inorganic materials 0.000 description 15
- 239000002245 particle Substances 0.000 description 13
- 239000006104 solid solution Substances 0.000 description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 12
- 239000013078 crystal Substances 0.000 description 12
- 239000007784 solid electrolyte Substances 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 239000002184 metal Substances 0.000 description 10
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 9
- 150000001875 compounds Chemical class 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- 239000011255 nonaqueous electrolyte Substances 0.000 description 8
- -1 etc.) Substances 0.000 description 7
- 239000011812 mixed powder Substances 0.000 description 7
- 239000002904 solvent Substances 0.000 description 7
- 239000000654 additive Substances 0.000 description 6
- 230000000996 additive effect Effects 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
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- 239000000047 product Substances 0.000 description 6
- 238000003786 synthesis reaction Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 229910021293 PO 4 Inorganic materials 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 4
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 4
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 4
- 229910000480 nickel oxide Inorganic materials 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 238000010828 elution Methods 0.000 description 3
- 150000002815 nickel Chemical class 0.000 description 3
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 3
- 239000011164 primary particle Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910018119 Li 3 PO 4 Inorganic materials 0.000 description 2
- 229910013684 LiClO 4 Inorganic materials 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- KLARSDUHONHPRF-UHFFFAOYSA-N [Li].[Mn] Chemical compound [Li].[Mn] KLARSDUHONHPRF-UHFFFAOYSA-N 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 239000006182 cathode active material Substances 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 2
- 229910052808 lithium carbonate Inorganic materials 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium;hydroxide;hydrate Chemical compound [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002905 metal composite material Substances 0.000 description 2
- 229910021382 natural graphite Inorganic materials 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 1
- YBJCDTIWNDBNTM-UHFFFAOYSA-N 1-methylsulfonylethane Chemical compound CCS(C)(=O)=O YBJCDTIWNDBNTM-UHFFFAOYSA-N 0.000 description 1
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- YEVQZPWSVWZAOB-UHFFFAOYSA-N 2-(bromomethyl)-1-iodo-4-(trifluoromethyl)benzene Chemical compound FC(F)(F)C1=CC=C(I)C(CBr)=C1 YEVQZPWSVWZAOB-UHFFFAOYSA-N 0.000 description 1
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 description 1
- GKZFQPGIDVGTLZ-UHFFFAOYSA-N 4-(trifluoromethyl)-1,3-dioxolan-2-one Chemical compound FC(F)(F)C1COC(=O)O1 GKZFQPGIDVGTLZ-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
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- 229910018133 Li 2 S-SiS 2 Inorganic materials 0.000 description 1
- 229910000733 Li alloy Inorganic materials 0.000 description 1
- 229910008745 Li2O-B2O3-P2O5 Inorganic materials 0.000 description 1
- 229910008523 Li2O-B2O3-ZnO Inorganic materials 0.000 description 1
- 229910008590 Li2O—B2O3—P2O5 Inorganic materials 0.000 description 1
- 229910008627 Li2O—B2O3—ZnO Inorganic materials 0.000 description 1
- 229910012722 Li3N-LiI-LiOH Inorganic materials 0.000 description 1
- 229910012716 Li3N-LiI—LiOH Inorganic materials 0.000 description 1
- 229910012734 Li3N—LiI—LiOH Inorganic materials 0.000 description 1
- 229910013043 Li3PO4-Li2S-SiS2 Inorganic materials 0.000 description 1
- 229910013035 Li3PO4-Li2S—SiS2 Inorganic materials 0.000 description 1
- 229910012810 Li3PO4—Li2S-SiS2 Inorganic materials 0.000 description 1
- 229910012804 Li3PO4—Li2S—Si2S Inorganic materials 0.000 description 1
- 229910012797 Li3PO4—Li2S—SiS2 Inorganic materials 0.000 description 1
- 229910012053 Li4SiO4-Li3VO4 Inorganic materials 0.000 description 1
- 229910012072 Li4SiO4—Li3VO4 Inorganic materials 0.000 description 1
- 229910010640 Li6BaLa2Ta2O12 Inorganic materials 0.000 description 1
- 229910015015 LiAsF 6 Inorganic materials 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910013184 LiBO Inorganic materials 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910010833 LiI-Li2S-SiS2 Inorganic materials 0.000 description 1
- 229910010823 LiI—Li2S—B2S3 Inorganic materials 0.000 description 1
- 229910010842 LiI—Li2S—P2O5 Inorganic materials 0.000 description 1
- 229910010855 LiI—Li2S—SiS2 Inorganic materials 0.000 description 1
- 229910010847 LiI—Li3PO4-P2S5 Inorganic materials 0.000 description 1
- 229910010864 LiI—Li3PO4—P2S5 Inorganic materials 0.000 description 1
- 229910014689 LiMnO Inorganic materials 0.000 description 1
- 229910013131 LiN Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 229910012254 LiPO4—Li2S—SiS Inorganic materials 0.000 description 1
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- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
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- 238000004458 analytical method Methods 0.000 description 1
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- CKFRRHLHAJZIIN-UHFFFAOYSA-N cobalt lithium Chemical compound [Li].[Co] CKFRRHLHAJZIIN-UHFFFAOYSA-N 0.000 description 1
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- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- VUPKGFBOKBGHFZ-UHFFFAOYSA-N dipropyl carbonate Chemical compound CCCOC(=O)OCCC VUPKGFBOKBGHFZ-UHFFFAOYSA-N 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
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- 239000011883 electrode binding agent Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
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- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
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- 229910001386 lithium phosphate Inorganic materials 0.000 description 1
- VROAXDSNYPAOBJ-UHFFFAOYSA-N lithium;oxido(oxo)nickel Chemical compound [Li+].[O-][Ni]=O VROAXDSNYPAOBJ-UHFFFAOYSA-N 0.000 description 1
- URIIGZKXFBNRAU-UHFFFAOYSA-N lithium;oxonickel Chemical compound [Li].[Ni]=O URIIGZKXFBNRAU-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
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- 238000002844 melting Methods 0.000 description 1
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- 239000011259 mixed solution Substances 0.000 description 1
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- MHYFEEDKONKGEB-UHFFFAOYSA-N oxathiane 2,2-dioxide Chemical compound O=S1(=O)CCCCO1 MHYFEEDKONKGEB-UHFFFAOYSA-N 0.000 description 1
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- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
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Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Description
本発明は、リチウムイオン二次電池用正極活物質、および該リチウムイオン二次電池用正極活物質の製造方法に関する。 The present invention relates to a positive electrode active material for a lithium ion secondary battery, and a method for producing the positive electrode active material for a lithium ion secondary battery.
近年、スマートフォン、タブレットＰＣ等の小型情報端末の急速な拡大とともに、充放電可能な電源として、リチウムイオン二次電池の需要が急激に伸びている。
このリチウムイオン二次電池に用いられる正極活物質としては、コバルト酸リチウム（ＬｉＣｏＯ２）に代表されるリチウムコバルト複合酸化物とともに、ニッケル酸リチウム（ＬｉＮｉＯ２）に代表されるリチウムニッケル複合酸化物、マンガン酸リチウム（ＬｉＭｎＯ２）に代表されるリチウムマンガン複合酸化物等が広く用いられている。
In recent years, with the rapid expansion of small information terminals such as smartphones and tablet PCs, the demand for lithium ion secondary batteries as chargeable and dischargeable power sources has increased rapidly.
The positive electrode active materials used in this lithium ion secondary battery include lithium cobalt composite oxides such as lithium cobalt oxide (LiCoO 2 ), lithium nickel composite oxides such as lithium nickel oxide (LiNiO 2 ), Lithium-manganese composite oxides such as lithium manganate (LiMnO 2 ) are widely used.
ところで、コバルト酸リチウムの主成分であるコバルトは、埋蔵量が少ないために高価かつ供給不安定で、価格の変動も大きい金属であるという問題点があった。このため、比較的安価なマンガンまたはニッケルを主成分とするリチウムマンガン複合酸化物またはリチウムニッケル複合酸化物がコストの観点から注目されている。
しかし、マンガン酸リチウムは、その熱安定性はコバルト酸リチウムに比べて優れているものの、充放電容量が他のリチウム金属複合酸化物に比べ小さく、かつ二次電池の寿命に関わる充放電サイクル特性に劣ることから、二次電池としての実用上の課題が多い。
By the way, cobalt, which is the main component of lithium cobalt oxide, has the problem that it is a metal that is expensive and has an unstable supply due to its small reserves, and its price fluctuates widely. For this reason, lithium-manganese composite oxides or lithium-nickel composite oxides containing relatively inexpensive manganese or nickel as main components are attracting attention from the viewpoint of cost.
However, although lithium manganate has superior thermal stability compared to lithium cobalt oxide, its charge/discharge capacity is smaller than other lithium metal composite oxides, and its charge/discharge cycle characteristics are related to the lifespan of secondary batteries. Because of this, there are many problems in practical use as a secondary battery.
一方、ニッケル酸リチウムは、コバルト酸リチウムよりも大きな充放電容量を示すことから、安価で高エネルギー密度の二次電池を製造することができる正極活物質として期待されている。
このニッケル酸リチウムは、通常、水酸化ニッケルまたは酸化ニッケルなどのニッケル化合物とリチウム化合物の混合物を焼成して製造されており、その形状は、一次粒子が単分散した粉末または一次粒子の集合体である二次粒子からなる粉末となる。
しかし、純粋なニッケル酸リチウムはリチウムが引き抜かれた充電状態での結晶構造の安定性がコバルト酸リチウムに劣るという欠点があり、熱安定性や充放電サイクル特性等の問題のため、実用電池としての利用は遅れていた。
On the other hand, since lithium nickelate exhibits a larger charge/discharge capacity than lithium cobaltate, it is expected to be a positive electrode active material that can be used to manufacture secondary batteries with high energy density at low cost.
This lithium nickelate is usually manufactured by firing a mixture of a nickel compound such as nickel hydroxide or nickel oxide and a lithium compound, and its shape is either a powder with monodispersed primary particles or an aggregate of primary particles. It becomes a powder consisting of certain secondary particles.
However, pure lithium nickel oxide has the disadvantage that its crystal structure is inferior to lithium cobalt oxide in the charged state where lithium is extracted, and due to problems such as thermal stability and charge/discharge cycle characteristics, it cannot be used as a practical battery. The use of was delayed.
このため、リチウムが引き抜かれた充電状態での結晶構造の安定化を図り、正極活物質として熱安定性および充放電サイクル特性が良好なリチウムニッケル複合酸化物を得るために、リチウムニッケル複合酸化物のニッケルの一部を他の元素と置換することが一般的に行われている。
例えば、ニッケルの一部を、コバルト、マンガン、鉄等の遷移金属元素や、アルミニウム、バナジウム、スズ等の金属元素などで置換することが行われている（例えば、特許文献１参照）。
Therefore, in order to stabilize the crystal structure in the charged state where lithium is extracted and to obtain a lithium-nickel composite oxide with good thermal stability and charge-discharge cycle characteristics as a positive electrode active material, we developed a lithium-nickel composite oxide. It is common practice to replace part of the nickel in other elements with other elements.
For example, a portion of nickel has been replaced with a transition metal element such as cobalt, manganese, or iron, or a metal element such as aluminum, vanadium, or tin (see, for example, Patent Document 1).
また、リチウムニッケル複合酸化物の熱安定性を改善させる方法として、焼成後のニッケル酸リチウムを水洗する技術が開発されている（例えば、特許文献２、３参照）。焼成後のニッケル酸リチウムを水洗すれば、リチウムイオン二次電池に採用した場合に、高容量で熱安定性や高温環境下での保存特性に優れた正極活物質が得られるとされている。
Further, as a method for improving the thermal stability of lithium-nickel composite oxide, a technique of washing lithium nickelate with water after firing has been developed (see, for example,
しかしながら、リチウムニッケル複合酸化物におけるニッケルの一部を他の金属元素で置換する場合、多量の元素置換を行う（リチウム以外の金属元素に占めるニッケル比率を低くする）と、熱安定性は高くなるものの電池容量の低下が生じる。
一方、電池容量の低下を防ぐために、元素置換を少量にとどめる（リチウム以外の金属元素に占めるニッケル比率を高くする）と、リチウムニッケル複合酸化物の熱安定性が十分に改善されない。また、ニッケル比率が高まると焼成時に、結晶構造中でリチウム以外の金属元素が占めるべきサイトにリチウムが入り込むカチオンミキシングが生じやすくなり、リチウムニッケル複合酸化物の合成が難しくなるという問題点もある。
However, when replacing part of the nickel in the lithium-nickel composite oxide with other metal elements, thermal stability will increase if a large amount of element substitution is performed (lowering the ratio of nickel to metal elements other than lithium). However, the battery capacity will decrease.
On the other hand, if element substitution is kept to a small amount (increasing the ratio of nickel to metal elements other than lithium) in order to prevent a decrease in battery capacity, the thermal stability of the lithium-nickel composite oxide will not be sufficiently improved. In addition, when the nickel ratio increases, cation mixing tends to occur during firing, where lithium enters sites that should be occupied by metal elements other than lithium in the crystal structure, making it difficult to synthesize a lithium-nickel composite oxide.
すなわち、ニッケルの一部を他の金属元素と置換したリチウムニッケル複合酸化物は種々開発されているものの、リチウムイオン二次電池における高容量化や高出力化の要求に十分に対応しているとはいえない。
同様に、焼成後のニッケル酸リチウムを水洗する方法を採用しても、リチウムイオン二次電池における高容量化や高出力化の要求に十分に対応したものは得られていない。
In other words, although various lithium-nickel composite oxides in which part of the nickel is replaced with other metal elements have been developed, it is difficult to believe that they fully meet the demands for higher capacity and higher output in lithium-ion secondary batteries. No, no.
Similarly, even if a method of washing lithium nickelate with water after firing is adopted, a lithium ion secondary battery that satisfactorily meets the demands for higher capacity and higher output has not been obtained.
以上のように、リチウムイオン二次電池に採用した場合に、高容量化や高出力化の要求に十分に対応できるリチウムニッケル複合酸化物からなる正極活物質は得られておらず、本発明は、このような高容量と高出力を示す電池特性を発現し得るリチウムニッケル複合酸化物を提供するものである。 As described above, a positive electrode active material made of a lithium-nickel composite oxide that can sufficiently meet the demands for higher capacity and higher output when used in a lithium ion secondary battery has not been obtained, and the present invention is The present invention provides a lithium-nickel composite oxide that can exhibit battery characteristics such as high capacity and high output.
発明者らは、上記課題を解決するために、正極活物質の合成に関する研究を進めた結果、水洗工程後のリチウムニッケル複合化合物中のニッケルと置換した元素の物質量比と、リチウムニッケル複合酸化物の結晶構造におけるｃ軸の長さに一定の相関関係があることを知見し、その相関関係が焼成合成時の最高到達温度により変化することを見出した。
さらに、焼成温度の範囲を調整することで、高容量かつ高出力なリチウムイオン二次電池を実現可能なリチウムニッケル複合酸化物が得られるとの知見を得て、本発明の完成に至ったものである。
In order to solve the above problems, the inventors conducted research on the synthesis of positive electrode active materials and found that the ratio of the amount of the element substituted for nickel in the lithium-nickel composite compound after the water washing process and the lithium-nickel composite oxide It was discovered that there is a certain correlation between the length of the c-axis in the crystal structure of a substance, and that this correlation changes depending on the maximum temperature reached during calcination synthesis.
Furthermore, it was discovered that by adjusting the firing temperature range, a lithium-nickel composite oxide capable of realizing high-capacity and high-output lithium-ion secondary batteries could be obtained, leading to the completion of the present invention. It is.
即ち、本発明の第１の発明は、一般式：ＬｉｚＮｉ１－ｘ－ｙＣｏｘＭｙＯ２（ただし、０．０１≦ｘ≦０．１９、０．０１≦ｙ≦０．１０、０．９５≦ｚ≦１．１０、ＭはＡｌ、又はＡｌとＭｎ、Ｖ、Ｍｇ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉから選ばれる少なくとも１種の元素とからなる）で表されるリチウムニッケル複合酸化物であり、前記リチウムニッケル複合酸化物のＸ線回折測定から得られた（００３）面回折ピークの半価幅を用いてＳｃｈｅｒｒｅｒ式により求めた結晶子径が、１００ｎｍ以上、１６０ｎｍ以下であり、前記Ｘ線回折測定結果からリートベルト解析を行なって求めた「３ａサイト」におけるリチウムの席占有率が、９７％以上であり、前記リチウムニッケル複合酸化物のＮｉとＣｏの物質量の和に対するＭの物質量の比［ｍＭ／（ｍＮｉ＋ｍＣｏ）］の百分率表示をα［％］とした時に、下記式（１）より求められる数値βよりも、ｃ軸格子定数（単位：ｎｍ）が小さいリチウムニッケル複合酸化物であることを特徴とするリチウムイオン二次電池用正極活物質である。 That is, the first invention of the present invention is based on the general formula: Li z Ni 1-x-y Co x M y O 2 (where 0.01≦x≦0.19, 0.01≦y≦0.10 , 0.95≦z≦1.10, M is Al, or a lithium-nickel composite consisting of Al and at least one element selected from Mn, V, Mg, W, Mo, Nb, and Ti) is an oxide , and has a crystallite diameter of 100 nm or more and 160 nm or less as determined by the Scherrer equation using the half width of the (003) plane diffraction peak obtained from the X-ray diffraction measurement of the lithium-nickel composite oxide. , the occupancy rate of lithium at the "3a site" determined by Rietveld analysis from the X-ray diffraction measurement results is 97% or more, and the occupancy rate of lithium is 97% or more with respect to the sum of the amounts of Ni and Co in the lithium-nickel composite oxide. When the percentage expression of the ratio of the amount of substance [m M / (m Ni + m Co )] is α [%], the c-axis lattice constant (unit: nm ) is a lithium-nickel composite oxide with small lithium ion secondary battery positive electrode active material.
本発明の第２の発明は、第１の発明に記載のリチウムイオン二次電池用正極活物質の製造方法であり、少なくともニッケルとコバルトを含み、ニッケルとコバルトおよび添加元素Ｍ（ＭはＡｌ、又はＡｌとＭｎ、Ｖ、Ｍｇ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉから選ばれる少なくとも１種の元素とからなる）の物質量比Ｎｉ：Ｃｏ：Ｍが１－ｘ－ｙ：ｘ：ｙであるニッケル化合物と、リチウム化合物とを混合して原料混合物を得る混合工程と、前記原料混合物を、酸素濃度が８０容量％以上の雰囲気中で、前記原料混合物の最高温度が７１５℃以上、７６５℃以下で、加熱開始から最高温度への到達およびその保持を経由して冷却が完了するまでの工程全体の時間である焼成時間は、８時間以上、２０時間以下となるように焼成してリチウムニッケル複合酸化物の焼成粉末を得る焼成工程と、前記リチウムニッケル複合酸化物の焼成粉末、７００ｇ以上、１２００ｇ以下を水と混合して１Ｌのスラリーとし、該スラリーのスラリー温度を１０℃以上、４０℃以下に維持しつつ、１０分以上、１時間以内で撹拌して前記リチウムニッケル複合酸化物を水洗処理した後、濾過、乾燥してリチウムニッケル複合酸化物粉末を得る水洗工程とを含むことを特徴とするリチウムイオン二次電池用正極活物質の製造方法である。 A second invention of the present invention is a method for producing a positive electrode active material for a lithium ion secondary battery according to the first invention, which contains at least nickel and cobalt, and an additive element M (M is Al, or nickel (consisting of Al and at least one element selected from Mn, V, Mg, W, Mo, Nb, Ti) whose material ratio Ni:Co:M is 1-xy:x:y a mixing step of mixing a compound and a lithium compound to obtain a raw material mixture; and mixing the raw material mixture in an atmosphere with an oxygen concentration of 80% by volume or more at a maximum temperature of the raw material mixture of 715°C or higher and 765°C or lower. The lithium-nickel composite oxide is baked so that the firing time, which is the time for the entire process from the start of heating to reaching the maximum temperature and maintaining it until cooling is completed, is 8 hours or more and 20 hours or less. A firing step for obtaining a fired powder of the product, and mixing 700 g or more and 1200 g or less of the fired powder of the lithium-nickel composite oxide with water to make 1 L of slurry, and setting the slurry temperature of the slurry to 10° C. or more and 40° C. or less. The lithium nickel composite oxide is washed with water by stirring for at least 10 minutes and within 1 hour while maintaining the temperature, followed by filtration and drying to obtain a lithium nickel composite oxide powder. This is a method for producing a positive electrode active material for a lithium ion secondary battery.
本発明によれば、得られた正極活物質は、リチウムイオン二次電池の正極材料として用いられた場合、高容量、高出力が得られるリチウムイオン二次電池とすることができるため、本発明の工業的価値は極めて大きい。 According to the present invention, when the obtained positive electrode active material is used as a positive electrode material of a lithium ion secondary battery, it can be used as a lithium ion secondary battery that can obtain high capacity and high output. The industrial value of is extremely large.
以下、本発明の実施の形態について詳細に説明する。
（１）リチウムイオン二次電池用の正極活物質およびその製造方法
リチウムイオン二次電池用の正極活物質であるリチウムニッケル複合酸化物を工業的に生産する場合、一般的に、原料混合物をセラミック製の焼成容器に充填し、ローラーハースキルンやプッシャー炉などの焼成炉中に連続的に送り込み、所定の時間、所定の温度で焼成し、下記反応式（Ａ）に例示するような合成反応を起こさせている。また、焼成に関する諸条件を検討する際は、バッチ式の雰囲気制御が可能なバッチ式電気炉を用いる場合もある。
Embodiments of the present invention will be described in detail below.
(1) Positive electrode active material for lithium ion secondary batteries and its manufacturing method When producing lithium nickel composite oxide, which is a positive electrode active material for lithium ion secondary batteries, on an industrial scale, generally the raw material mixture is The mixture is filled into a manufactured baking container, continuously fed into a baking furnace such as a roller hearth kiln or a pusher furnace, and baked for a predetermined time and at a predetermined temperature to carry out a synthesis reaction as exemplified by the following reaction formula (A). I'm making it happen. Furthermore, when considering various conditions for firing, a batch-type electric furnace capable of batch-type atmosphere control may be used.
さらに、生産性を高くするために、匣鉢の搬送速度を速めて全焼成時間を短縮する方法があるが、焼成時間が短すぎると原料混合物の反応に必要な熱が十分に伝わらず、合成反応が完全に進まないために電池性能を劣化させてしまうという問題がある。
そこで、合成反応を促進するために焼成温度を高くする方法があるが、焼成温度が高すぎると、リチウムニッケル複合酸化物結晶中の添加元素、例えばＡｌなどが結晶中から脱離してしまい、目的とするＡｌの添加効果が得られず、熱安定性や電池性能を劣化させてしまうという問題がある。
そして、その脱離したＡｌは粒子表面でリチウムとの可溶性化合物を形成するので、Ａｌの脱離が大きい正極活物質は、水洗処理するとＡｌとリチウムの化合物が除去されてしまい、水洗前後でＡｌの品位が低下する。
Furthermore, in order to increase productivity, there is a method to shorten the total firing time by increasing the transport speed of the saggers, but if the firing time is too short, the heat required for the reaction of the raw material mixture will not be transmitted sufficiently, resulting in There is a problem that battery performance deteriorates because the reaction does not proceed completely.
Therefore, there is a method of increasing the firing temperature to promote the synthesis reaction, but if the firing temperature is too high, added elements such as Al in the lithium nickel composite oxide crystal will be eliminated from the crystal, resulting in the desired purpose. There is a problem that the desired effect of adding Al cannot be obtained, and the thermal stability and battery performance deteriorate.
Then, the released Al forms a soluble compound with lithium on the particle surface, so if a positive electrode active material with a large amount of Al released is washed with water, the compound of Al and lithium will be removed, and the Al and lithium compounds will be removed before and after washing with water. The quality of the product deteriorates.
また、添加元素の残留量、例えばＡｌの残留量を、メタル比：αＡｌ［％］＝１００×ｍＡｌ［ｍｏｌ］／（ｍＮｉ＋ｍＣｏ）［ｍｏｌ］で表わすと、実験により、その上限値αＡｌ １は、αＡｌ １＝ｍＡｌ［ｍｏｌ]＋０．５が得られ、その時に、αＡｌ＞αＡｌ １－１にある場合、Ａｌの溶出を抑えたため優れた電池特性が発現する。 In addition, when the residual amount of an additive element, for example, the residual amount of Al, is expressed as metal ratio: α Al [%] = 100 × m Al [mol] / (m Ni + m Co ) [mol], the upper limit is determined by experiment. The value α Al 1 is α Al 1 = m Al [mol] + 0.5, and when α Al > α Al 1 -1, excellent battery characteristics are exhibited because the elution of Al is suppressed. .
従って、良好な電池性能を得るためには、前記のような添加元素の脱離が起こりにくい温度域で、リチウムニッケル複合酸化物の合成反応に必要な熱量を原料混合物へ加えることが必要となる。
ここで、発明者らは、ニッケル複合酸化物とリチウム化合物からなる原料混合物の焼成工程において、結晶成長を促進する温度領域として７１５℃以上、７６５℃以下の範囲で、保持時間を適宜設定することで、添加元素の溶出を抑えられ、かつ電池特性に優れた正極材料が得られる知見を見出した。
Therefore, in order to obtain good battery performance, it is necessary to add the amount of heat necessary for the synthesis reaction of the lithium-nickel composite oxide to the raw material mixture in a temperature range where desorption of the added elements as mentioned above is difficult to occur. .
Here, the inventors have proposed that in the firing process of the raw material mixture consisting of a nickel composite oxide and a lithium compound, the holding time should be appropriately set within a temperature range of 715°C or higher and 765°C or lower to promote crystal growth. We have discovered that it is possible to suppress the elution of additive elements and obtain a positive electrode material with excellent battery characteristics.
また、リチウムニッケル複合酸化物ＬｉｚＮｉ１－ｘ－ｙＣｏｘＭｙＯ２が電池特性に優れた正極活物質であるためには、Ｘ線回折のリートベルト解析から得られるｃ軸の長さが、ＮｉとＣｏの物質量（ｍＮｉ、ｍＣｏ）の和に対するＭの物質量（ｍＭ）の比（ｍＭ／［ｍＮｉ＋ｍＣｏ］）の百分率表示であるメタル比：αＭ［％］との関係において、下記式（２）により求められる値βＭよりも、小さいことが必要なことを見出した。 In addition, in order for the lithium nickel composite oxide Li z Ni 1-x-y C x M y O 2 to be a positive electrode active material with excellent battery properties, the c-axis length obtained from Rietveld analysis of X-ray diffraction is The metal ratio: α M is the ratio (m M /[m Ni + m Co ]) of the amount of M (m M ) to the sum of the amounts of Ni and Co (m Ni , m Co ). It has been found that the relationship with [%] needs to be smaller than the value β M determined by the following formula (2).
この焼成における最高温度が７６５℃より高い場合、Ａｌの溶出が多くαＡｌ＜αＡｌ
１－１となってしまい、Ａｌが結晶中に含まれることによる結晶構造の安定性が乱されるため、熱に対する正極材料の安定性が低下することや、充放電サイクル時の寿命劣化が起こる。
又、最高温度が７１５℃より低い場合、Ｘ線回折測定により得られた結晶子径サイズが小さくなり、結晶子同士の界面が多くなってしまうことから、充放電時のリチウムイオンの拡散抵抗が大きくなり、電池性能が劣化する。
If the maximum temperature in this firing is higher than 765°C, a large amount of Al will be eluted, and α Al < α Al 1 -1, and the stability of the crystal structure due to Al being included in the crystal will be disturbed. The stability of the cathode material against heat decreases, and the lifespan deteriorates during charge/discharge cycles.
In addition, if the maximum temperature is lower than 715°C, the crystallite size obtained by X-ray diffraction measurement becomes smaller and the number of interfaces between crystallites increases, so the diffusion resistance of lithium ions during charging and discharging increases. becomes larger, and battery performance deteriorates.
次に、保持時間に関しては、ある程度以上長い時間をかけて合成すれば、十分な結晶性を維持し、かつ電池性能を損なわずに合成することが可能であるが、工業的な生産性を考慮した場合、焼成時間はなるべく短い方が好ましい。したがって、混合物の入った焼成容器が焼成用の炉に入ってから出てくるまで、すなわち、加熱開始から最高温度への到達およびその保持を経由して冷却が完了する（焼成物の温度が１５０℃以下となる）までの工程全体の時間（焼成時間）は、２０時間以下とすることが好ましい。一方、温度を急激に上昇させると、焼成容器内の混合物の温度が不均一となり、反応も均一にならない場合があるため、前記加熱開始から冷却完了までの時間（焼成時間）は、８時間以上とすることが好ましい。 Next, regarding retention time, it is possible to maintain sufficient crystallinity and synthesize without impairing battery performance if the synthesis is carried out over a certain period of time, but considering industrial productivity. In this case, it is preferable that the firing time be as short as possible. Therefore, cooling is completed from the time the firing container containing the mixture enters the firing furnace until it comes out, that is, from the start of heating to reaching the maximum temperature and maintaining it (the temperature of the fired product is 150 It is preferable that the entire process time (baking time) until the temperature reaches 20 hours or less (firing time) is 20 hours or less. On the other hand, if the temperature is increased rapidly, the temperature of the mixture in the firing container may become uneven, and the reaction may not be uniform. It is preferable that
本発明の製造方法においては、前記混合物の原料となるニッケル複合酸化物の平均粒径を８～３０μｍの範囲内とする。平均粒径が８μｍ未満では、得られる正極活物質物の粒径も小さくなり、体積あたりの充填量が少なく、電池の容量が低下する。また、焼成中に焼結が生じやすく、粗大な正極活物質が生成されて電池特性が低下する。一方、平均粒径が３０μｍを超えても、正極活物質間の接点が少なく、正極の抵抗が上昇して、電池容量が低下する。 In the production method of the present invention, the average particle size of the nickel composite oxide, which is the raw material for the mixture, is within the range of 8 to 30 μm. If the average particle size is less than 8 μm, the particle size of the obtained positive electrode active material will also be small, the filling amount per volume will be small, and the capacity of the battery will be reduced. In addition, sintering tends to occur during firing, producing coarse positive electrode active material and deteriorating battery characteristics. On the other hand, even if the average particle size exceeds 30 μm, there are fewer contact points between the positive electrode active materials, the resistance of the positive electrode increases, and the battery capacity decreases.
さらに、ニッケル複合化合物とリチウム化合物を混合して得られる混合物の嵩密度を１．０～２．２ｇ／ｍｌの範囲内とするのが好ましい。この嵩密度が１．０ｇ／ｍｌ未満では、焼成容器へ一定量充填する際に必要な焼成容器の必要容量が大きくなりすぎて、生産性を著しく低下させる。一方、嵩密度が２．２ｇ／ｍｌを超えると、混合物が密に詰まることで酸素拡散が遅くなり、焼成に必要な時間が延びて生産性を低下させる。 Further, it is preferable that the bulk density of the mixture obtained by mixing the nickel composite compound and the lithium compound is within the range of 1.0 to 2.2 g/ml. If the bulk density is less than 1.0 g/ml, the required capacity of the firing container becomes too large when filling a certain amount into the firing container, resulting in a significant decrease in productivity. On the other hand, when the bulk density exceeds 2.2 g/ml, the mixture becomes densely packed, which slows down oxygen diffusion, prolongs the time required for firing, and reduces productivity.
混合物の原料として用いるリチウム化合物は、特に限定されるものではないが、水酸化リチウムまたは炭酸リチウムが好ましく、融点が４８０℃付近にある水酸化リチウムまたは水酸化リチウム水和物が、ニッケル複合酸化物との反応を考慮すると特に好ましい。水酸化リチウムが溶融し、ニッケル複合酸化物と固液反応することでより、均一に反応が進むからである。 The lithium compound used as a raw material for the mixture is not particularly limited, but lithium hydroxide or lithium carbonate is preferable, and lithium hydroxide or lithium hydroxide hydrate, which has a melting point around 480°C, is preferable for nickel composite oxide. This is particularly preferable in consideration of the reaction with. This is because lithium hydroxide melts and undergoes a solid-liquid reaction with the nickel composite oxide, which allows the reaction to proceed uniformly.
また、混合物の原料として用いるニッケル複合化合物も、特に限定されるものではないが、反応中に水以外の副反応物を生成しないという観点から、ニッケル複合水酸化物またはニッケル複合酸化物が好ましい。 Further, the nickel composite compound used as a raw material for the mixture is not particularly limited, but a nickel composite hydroxide or a nickel composite oxide is preferable from the viewpoint of not producing by-products other than water during the reaction.
本発明の製造方法においては、焼成によって得られたリチウムニッケル複合酸化物を水洗することで、リチウムニッケル複合酸化物粒子表面の余剰のリチウムが除去され、高容量で安全性が高いリチウムイオン二次電池用正極活物質となる。 In the manufacturing method of the present invention, by washing the lithium-nickel composite oxide obtained by firing with water, excess lithium on the surface of the lithium-nickel composite oxide particles is removed, resulting in a high capacity and highly safe lithium ion secondary It becomes a positive electrode active material for batteries.
ここで、水洗方法としては、例えば、水洗する際のスラリー濃度として、好ましくは、質量比で水１に対してリチウムニッケル複合酸化物を０．５～２を投入し、リチウムニッケル複合酸化物粒子表面の余剰のリチウムが十分に除去される間、撹拌した後、固液分離して乾燥すればよい。スラリー濃度が質量比で２を超えると、粘度も非常に高いため撹拌が困難となるばかりか、液中のアルカリが高いので平衡の関係から付着物の溶解速度が遅くなったり、剥離が起きても粉末からの分離が難しくなったりすることがある。
一方、スラリー濃度が質量比で０．５未満では、希薄過ぎるためリチウムの溶出量が多く、正極活物質の結晶格子中からのリチウムの脱離も起きるようになり、結晶が崩れやすくなるばかりか、高ｐＨの水溶液が大気中の炭酸ガスを吸収して炭酸リチウムを再析出する。
Here, as for the water washing method, for example, the slurry concentration at the time of water washing is preferably such that 0.5 to 2 parts of lithium nickel composite oxide are added to 1 part of water in a mass ratio, and the lithium nickel composite oxide particles are After stirring while excess lithium on the surface is sufficiently removed, solid-liquid separation may be performed and then dried. If the slurry concentration exceeds 2 in terms of mass ratio, not only will the viscosity be very high, making stirring difficult, but also the high alkali content in the liquid will slow down the dissolution rate of deposits and cause peeling. It may also be difficult to separate it from the powder.
On the other hand, if the slurry concentration is less than 0.5 in terms of mass ratio, the slurry is too dilute and a large amount of lithium is eluted, causing lithium to be desorbed from the crystal lattice of the positive electrode active material, which not only makes the crystal more likely to collapse. , a high pH aqueous solution absorbs carbon dioxide gas in the atmosphere and reprecipitates lithium carbonate.
上記水洗に使用する水は、特に限定されるものではないが、電気伝導率測定で１０μＳ／ｃｍ未満の水が好ましく、１μＳ／ｃｍ以下の水がより好ましい。
即ち、電気伝導率測定で１０μＳ／ｃｍ未満の水を使用することにより、正極活物質への不純物の付着による電池性能の低下を防止することが可能となる。
上記スラリーの固液分離時の粒子表面に残存する付着水は少ないことが好ましい。
この付着水が多いと、液中に溶解したリチウムが再析出し、乾燥後のリチウムニッケル複合酸化物粉末の表面に存在するリチウム量が増加する。固液分離には、通常に用いられる遠心機、フィルタープレスなどが用いられる。
The water used for the washing is not particularly limited, but preferably has an electrical conductivity of less than 10 μS/cm, more preferably 1 μS/cm or less.
That is, by using water with an electrical conductivity of less than 10 μS/cm in the measurement of electrical conductivity, it is possible to prevent deterioration in battery performance due to adhesion of impurities to the positive electrode active material.
It is preferable that the amount of adhering water remaining on the particle surface during solid-liquid separation of the slurry is small.
If there is a large amount of this attached water, the lithium dissolved in the liquid will re-precipitate, and the amount of lithium present on the surface of the lithium-nickel composite oxide powder after drying will increase. For solid-liquid separation, commonly used centrifuges, filter presses, etc. are used.
乾燥の温度は、特に限定されるものではないが、好ましくは８０～５５０℃、さらに好ましくは１２０～３５０℃である。
８０℃以上とするのは、水洗後の正極活物質を素早く乾燥し、粒子表面と粒子内部とでリチウム濃度の勾配が起こることを防ぐためである。一方、正極活物質の表面付近では化学量論比にきわめて近いか、もしくは若干リチウムが脱離して充電状態に近い状態になっていることが予想されるので、５５０℃を超える温度では、充電状態に近い粉末の結晶構造が崩れる契機になり、電気特性の低下を招くおそれがある。さらに、生産性および熱エネルギーコストをも考慮すると、１２０～３５０℃がより好ましい。
このとき、乾燥方法としては、濾過後の粉末を、炭素および硫黄を含む化合物成分を含有しないガス雰囲気下、または真空雰囲気下に制御できる乾燥機を用いて、所定の温度で行うことが好ましい。
The drying temperature is not particularly limited, but is preferably 80 to 550°C, more preferably 120 to 350°C.
The reason for setting the temperature to 80° C. or higher is to quickly dry the positive electrode active material after washing with water and to prevent a lithium concentration gradient from occurring between the particle surface and the inside of the particle. On the other hand, near the surface of the positive electrode active material, it is expected that the stoichiometric ratio is very close to that of the lithium, or that lithium is slightly desorbed and the state is close to the charged state. This may cause the crystal structure of the powder close to that of the powder to collapse, leading to a decrease in electrical properties. Furthermore, in consideration of productivity and thermal energy cost, the temperature is more preferably 120 to 350°C.
At this time, the drying method is preferably carried out at a predetermined temperature using a dryer that can control the filtered powder under a gas atmosphere that does not contain carbon and sulfur-containing compound components or under a vacuum atmosphere.
本発明は、さまざまなリチウムニッケル複合酸化物から構成される、リチウムイオン二次電池用の正極活物質の工業的な製造に適用することが可能であるが、特に、その組成が、一般式：ＬｉｚＮｉ１－ｘ－ｙＣｏｘＭｙＯ２（ただし、０．０１≦ｘ≦０．１９、０．０１≦ｙ≦０．１０、０．９５≦ｚ≦１．１０、ＭはＡｌ、又はＡｌとＭｎ、Ｖ、Ｍｇ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉから選ばれる少なくとも１種の元素とからなる）で表されるリチウムニッケル複合酸化物に好適に適用される。 The present invention can be applied to the industrial production of cathode active materials for lithium ion secondary batteries, which are composed of various lithium-nickel composite oxides, but in particular, the composition is of the general formula: Li z Ni 1-x-y Co x M y O 2 (0.01≦x≦0.19, 0.01≦y≦0.10, 0.95≦z≦1.10, M is Al , or consisting of Al and at least one element selected from Mn, V, Mg, W, Mo, Nb, and Ti).
上記リチウムニッケル複合酸化物の原料となる、ニッケル複合水酸化物またはニッケル複合酸化物は、公知の方法に基づいて得ることができる。たとえば、ニッケルとコバルトおよび添加元素Ｍを共沈させることによりニッケル複合水酸化物を得ることができる。さらに、ニッケル複合水酸化物を酸化焙焼することにより、コバルトおよび添加元素Ｍが酸化ニッケルに固溶しているニッケル複合酸化物が得られる。ただし、ニッケル酸化物とその他の添加元素の酸化物を粉砕混合するなどのその他の手段によっても得ることは可能である。
本発明が提供するリチウムイオン二次電池用の正極活物質は、上記製造方法で得られるものであり、リチウムイオン二次電池に用いられた場合には、高容量で安全性の高い電池となる。
Nickel composite hydroxide or nickel composite oxide, which is a raw material for the lithium-nickel composite oxide, can be obtained based on a known method. For example, a nickel composite hydroxide can be obtained by coprecipitating nickel, cobalt, and the additive element M. Further, by oxidizing and roasting the nickel composite hydroxide, a nickel composite oxide in which cobalt and the additive element M are dissolved in nickel oxide can be obtained. However, it is also possible to obtain it by other means such as pulverizing and mixing nickel oxide and oxides of other additive elements.
The positive electrode active material for lithium ion secondary batteries provided by the present invention is obtained by the above manufacturing method, and when used in lithium ion secondary batteries, it becomes a battery with high capacity and high safety. .
（２）リチウムイオン二次電池
本発明のリチウムイオン二次電池は、正極、負極及び非水系電解液などからなり、一般のリチウムイオン二次電池と同様の構成要素により構成される。なお、以下で説明する実施形態は例示に過ぎず、本発明のリチウムイオン二次電池は、本明細書に記載されている実施形態を基に、当業者の知識に基づいて種々の変更、改良を施した形態で実施することができる。また、本発明のリチウムイオン二次電池は、その用途を特に限定するものではない。
(2) Lithium ion secondary battery The lithium ion secondary battery of the present invention includes a positive electrode, a negative electrode, a non-aqueous electrolyte, and the like, and is constructed from the same components as a general lithium ion secondary battery. The embodiments described below are merely examples, and the lithium ion secondary battery of the present invention can be modified and improved based on the embodiments described in this specification based on the knowledge of those skilled in the art. It can be implemented in a form with Moreover, the lithium ion secondary battery of the present invention is not particularly limited in its use.
（ａ）正極
先に述べたリチウムイオン二次電池用正極活物質を用い、例えば、以下のようにして、リチウムイオン二次電池の正極を作製する。
まず、粉末状の正極活物質、導電材、結着剤を混合し、さらに必要に応じて活性炭、粘度調整等の目的の溶剤を添加し、これを混練して正極合剤ペーストを作製する。
この時、その正極合剤ペースト中のそれぞれの混合比も、リチウムイオン二次電池の性能を決定する重要な要素となる。溶剤を除いた正極合剤の固形分の全質量を１００質量部とした場合、一般のリチウムイオン二次電池の正極と同様、正極活物質の含有量を６０～９５質量部とし、導電材の含有量を１～２０質量部とし、結着剤の含有量を１～２０質量部とすることが好ましい。
(a) Positive electrode A positive electrode for a lithium ion secondary battery is produced, for example, in the following manner using the positive electrode active material for a lithium ion secondary battery described above.
First, a powdered positive electrode active material, a conductive material, and a binder are mixed, and if necessary, activated carbon and a solvent for purposes such as viscosity adjustment are added, and the mixture is kneaded to prepare a positive electrode mixture paste.
At this time, the respective mixing ratios in the positive electrode mixture paste are also important factors that determine the performance of the lithium ion secondary battery. Assuming that the total mass of the solid content of the positive electrode mixture excluding the solvent is 100 parts by mass, the content of the positive electrode active material is 60 to 95 parts by mass, similar to the positive electrode of general lithium ion secondary batteries, and the content of the conductive material is 60 to 95 parts by mass. It is preferable that the content is 1 to 20 parts by mass, and the content of the binder is 1 to 20 parts by mass.
その得られた正極合剤ペーストを、例えば、アルミニウム箔製の集電体の表面に塗布し、乾燥して、溶剤を飛散させる。必要に応じ、電極密度を高めるべく、ロールプレス等により加圧することもある。このようにして、シート状の正極を作製することができる。
シート状の正極は、目的とする電池に応じて適当な大きさに裁断等をして、電池の作製に供することができる。ただし、正極の作製方法は、例示のものに限られることなく、他の方法によってもよい。
The obtained positive electrode mixture paste is applied to the surface of a current collector made of aluminum foil, for example, and dried to scatter the solvent. If necessary, pressure may be applied using a roll press or the like to increase the electrode density. In this way, a sheet-like positive electrode can be produced.
The sheet-like positive electrode can be cut into an appropriate size depending on the intended battery and used for battery production. However, the method for producing the positive electrode is not limited to the exemplified method, and other methods may be used.
正極の作製にあたって、黒鉛（天然黒鉛、人造黒鉛、膨張黒鉛など）や、アセチレンブラック、ケッチェンブラック（登録商標）などのカーボンブラック系材料などを導電剤として添加することができる。
又、活物質粒子をつなぎ止める役割を果たす結着剤には、例えば、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、フッ素ゴム、エチレンプロピレンジエンゴム、スチレンブタジエン、セルロース系樹脂、ポリアクリル酸などを用いることができる。
なお、必要に応じ、正極活物質、導電剤、活性炭を分散させ、結着剤を溶解する溶剤を正極合剤に添加する。
In producing the positive electrode, graphite (natural graphite, artificial graphite, expanded graphite, etc.), carbon black-based materials such as acetylene black, Ketjenblack (registered trademark), etc. can be added as a conductive agent.
In addition, examples of binders that bind active material particles include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), fluororubber, ethylene propylene diene rubber, styrene butadiene, cellulose resin, and polyacrylic resin. An acid etc. can be used.
Note that, if necessary, a solvent for dispersing the positive electrode active material, conductive agent, and activated carbon and dissolving the binder is added to the positive electrode mixture.
溶剤としては、具体的には、Ｎ－メチル－２－ピロリドン等の有機溶剤を用いることができる。また、正極合剤には、電気二重層容量を増加させるために、活性炭を添加することができる。 Specifically, an organic solvent such as N-methyl-2-pyrrolidone can be used as the solvent. Furthermore, activated carbon can be added to the positive electrode mixture in order to increase the electric double layer capacity.
（ｂ）負極
負極には、金属リチウムやリチウム合金等、あるいは、リチウムイオンを吸蔵及び脱離できる負極活物質に、結着剤を混合し、適当な溶剤を加えてペースト状にした負極合材を、銅等の金属箔集電体の表面に塗布し、乾燥し、必要に応じて電極密度を高めるべく圧縮して形成したものを使用する。
(b) Negative electrode The negative electrode is made of metal lithium, lithium alloy, etc., or a negative electrode composite made by mixing a binder with a negative electrode active material that can absorb and desorb lithium ions, and adding an appropriate solvent to form a paste. is applied onto the surface of a metal foil current collector made of copper or the like, dried, and compressed to increase the electrode density if necessary.
負極活物質としては、例えば、天然黒鉛、人造黒鉛、フェノール樹脂等の有機化合物焼成体、コークス等の炭素物質の粉状体を用いることができる。この場合、負極結着剤としては、正極同様、ＰＶＤＦ等の含フッ素樹脂等を用いることができ、これらの活物質及び結着剤を分散させる溶剤としては、Ｎ－メチル－２－ピロリドン等の有機溶剤を用いることができる。 As the negative electrode active material, for example, natural graphite, artificial graphite, fired organic compounds such as phenol resin, and powdered carbon materials such as coke can be used. In this case, as the negative electrode binder, a fluororesin such as PVDF can be used as in the positive electrode, and as a solvent for dispersing these active materials and binder, N-methyl-2-pyrrolidone or the like can be used. Organic solvents can be used.
（ｃ）セパレータ
正極と負極との間には、セパレータを挟み込んで配置する。
セパレータは、正極と負極とを分離し、電解質を保持するものであり、ポリエチレン、ポリプロピレン等の薄い膜で、微少な孔を多数有する膜を用いることができる。
(c) Separator A separator is placed between the positive electrode and the negative electrode.
The separator separates the positive electrode and the negative electrode and holds the electrolyte, and can be a thin film made of polyethylene, polypropylene, etc., and has many minute pores.
（ｄ）非水系電解質
非水系電解質としては、非水系電解液、固体電解質などが用いられる。
非水系電解液は、支持塩としてのリチウム塩を有機溶媒に溶解したものである。
使用する有機溶媒としては、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、トリフルオロプロピレンカーボネート等の環状カーボネート、また、ジエチルカーボネート、ジメチルカーボネート、エチルメチルカーボネート、ジプロピルカーボネート等の鎖状カーボネート、さらに、テトラヒドロフラン、２－メチルテトラヒドロフラン、ジメトキシエタン等のエーテル化合物、エチルメチルスルホン、ブタンスルトン等の硫黄化合物、リン酸トリエチル、リン酸トリオクチル等のリン化合物等から選ばれる１種を単独で、あるいは２種以上を混合して用いることができる。
支持塩としては、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＣｌＯ４、ＬｉＡｓＦ６、ＬｉＮ（ＣＦ３ＳＯ２）２等、及びそれらの複合塩を用いることができる。
さらに、非水系電解液は、ラジカル捕捉剤、界面活性剤及び難燃剤等を含んでいてもよい。
(d) Non-aqueous electrolyte As the non-aqueous electrolyte, a non-aqueous electrolyte, a solid electrolyte, etc. are used.
The non-aqueous electrolyte is a solution in which a lithium salt as a supporting salt is dissolved in an organic solvent.
Examples of organic solvents used include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, and dipropyl carbonate, and tetrahydrofuran. One type selected from ether compounds such as 2-methyltetrahydrofuran and dimethoxyethane, sulfur compounds such as ethylmethylsulfone and butane sultone, and phosphorus compounds such as triethyl phosphate and trioctyl phosphate, etc., or a mixture of two or more types. It can be used as
As the supporting salt, LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiN(CF 3 SO 2 ) 2 , etc., and complex salts thereof can be used.
Furthermore, the nonaqueous electrolyte may contain a radical scavenger, a surfactant, a flame retardant, and the like.
一方、固体電解質としては、酸化物系固体電解質、硫化物系固体電解質などが用いられる。
酸化物系固体電解質としては、特に限定されず、酸素（Ｏ）を含有し、かつ、リチウムイオン伝導性と電子絶縁性とを有するものであれば用いることができる。酸化物系固体電解質としては、例えば、リン酸リチウム（Ｌｉ３ＰＯ４）、Ｌｉ３ＰＯ４ＮＸ、ＬｉＢＯ２ＮＸ、ＬｉＮｂＯ３、ＬｉＴａＯ３、Ｌｉ２ＳｉＯ３、Ｌｉ４ＳｉＯ４－Ｌｉ３ＰＯ４、Ｌｉ４ＳｉＯ４－Ｌｉ３ＶＯ４、Ｌｉ２Ｏ－Ｂ２Ｏ３－Ｐ２Ｏ５、Ｌｉ２Ｏ－ＳｉＯ２、Ｌｉ２Ｏ－Ｂ２Ｏ３－ＺｎＯ、Ｌｉ１＋ＸＡｌＸＴｉ２－Ｘ（ＰＯ４）３（０≦Ｘ≦１）、Ｌｉ１＋ＸＡｌＸＧｅ２－Ｘ（ＰＯ４）３（０≦Ｘ≦１）、ＬｉＴｉ２（ＰＯ４）３、Ｌｉ３ＸＬａ２／３－ＸＴｉＯ３（０≦Ｘ≦２／３）、Ｌｉ５Ｌａ３Ｔａ２Ｏ１２、Ｌｉ７Ｌａ３Ｚｒ２Ｏ１２、Ｌｉ６ＢａＬａ２Ｔａ２Ｏ１２、Ｌｉ３．６Ｓｉ０．６Ｐ０．４Ｏ４等が挙げられる。
硫化物系固体電解質としては、特に限定されず、硫黄（Ｓ）を含有し、かつ、リチウムイオン伝導性と電子絶縁性とを有するものであれば用いることができる。硫化物系固体電解質としては、例えば、Ｌｉ２Ｓ－Ｐ２Ｓ５、Ｌｉ２Ｓ－ＳｉＳ２、ＬｉＩ－Ｌｉ２Ｓ－ＳｉＳ２、ＬｉＩ－Ｌｉ２Ｓ－Ｐ２Ｓ５、ＬｉＩ－Ｌｉ２Ｓ－Ｂ２Ｓ３、Ｌｉ３ＰＯ４－Ｌｉ２Ｓ－Ｓｉ２Ｓ、Ｌｉ３ＰＯ４－Ｌｉ２Ｓ－ＳｉＳ２、ＬｉＰＯ４－Ｌｉ２Ｓ－ＳｉＳ、ＬｉＩ－Ｌｉ２Ｓ－Ｐ２Ｏ５、ＬｉＩ－Ｌｉ３ＰＯ４－Ｐ２Ｓ５等が挙げられる。
On the other hand, as the solid electrolyte, oxide-based solid electrolytes, sulfide-based solid electrolytes, etc. are used.
The oxide-based solid electrolyte is not particularly limited, and any material that contains oxygen (O) and has lithium ion conductivity and electronic insulation can be used. Examples of oxide - based solid electrolytes include lithium phosphate ( Li 3 PO 4 ) , Li 3 PO 4 N X , LiBO 2 N PO 4 , Li 4 SiO 4 -Li 3 VO 4 , Li 2 O-B 2 O 3 -P 2 O 5 , Li 2 O-SiO 2 , Li 2 O-B 2 O 3 -ZnO, Li 1+X Al X Ti 2-X (PO 4 ) 3 (0≦X≦1), Li 1+X Al X Ge 2-X (PO 4 ) 3 (0≦X≦1), LiTi 2 (PO 4 ) 3 , Li 3 3-X TiO 3 (0≦X≦2/3), Li 5 La 3 Ta 2 O 12 , Li 7 La 3 Zr 2 O 12 , Li 6 BaLa 2 Ta 2 O 12 , Li 3.6 Si 0.6 Examples include P 0.4 O 4 and the like.
The sulfide-based solid electrolyte is not particularly limited, and any material can be used as long as it contains sulfur (S) and has lithium ion conductivity and electronic insulation. Examples of the sulfide solid electrolyte include Li 2 SP 2 S 5 , Li 2 S-SiS 2 , LiI-Li 2 S-SiS 2 , LiI- Li 2 SP 2 S 5 , LiI-Li 2 S-B 2 S 3 , Li 3 PO 4 -Li 2 S-Si 2 S, Li 3 PO 4 -Li 2 S-SiS 2 , LiPO 4 -Li 2 S-SiS, LiI-Li 2 S-P 2 O 5 , LiI-Li 3 PO 4 -P 2 S 5 , and the like.
なお、無機固体電解質としては、上記以外のものを用いてよく、例えば、Ｌｉ３Ｎ、ＬｉＩ、Ｌｉ３Ｎ－ＬｉＩ－ＬｉＯＨ等を用いてもよい。
有機固体電解質としては、イオン電導性を示す高分子化合物であれば、特に限定されず、例えば、ポリエチレンオキシド、ポリプロピレンオキシド、これらの共重合体などを用いることができる。また、有機固体電解質は、支持塩（リチウム塩）を含んでいてもよい。なお、固体電解質を用いる場合は、電解質と正極活物質の接触を確保するため、正極材中にも固体電解質を混合させてもよい。
Note that as the inorganic solid electrolyte, other than those mentioned above may be used, for example, Li 3 N, LiI, Li 3 N-LiI-LiOH, etc. may be used.
The organic solid electrolyte is not particularly limited as long as it is a polymer compound that exhibits ionic conductivity, and for example, polyethylene oxide, polypropylene oxide, copolymers thereof, etc. can be used. Moreover, the organic solid electrolyte may contain a supporting salt (lithium salt). Note that when a solid electrolyte is used, the solid electrolyte may also be mixed in the positive electrode material in order to ensure contact between the electrolyte and the positive electrode active material.
（ｅ）電池の形状、構成
以上、説明した正極、負極、セパレータ及び非水系電解液で構成される本発明のリチウムイオン二次電池の形状は、円筒型、積層型等、種々のものとすることができる。
いずれの形状を採る場合であっても、正極及び負極を、セパレータを介して積層させて電極体とし、得られた電極体に、非水系電解液を含浸させ、正極集電体と外部に通ずる正極端子との間、及び、負極集電体と外部に通ずる負極端子との間を、集電用リード等を用いて接続し、電池ケースに密閉して、リチウムイオン二次電池を完成させる。
(e) Shape and structure of battery The lithium ion secondary battery of the present invention, which is composed of the positive electrode, negative electrode, separator, and non-aqueous electrolyte described above, may have various shapes such as cylindrical, laminated, etc. be able to.
Regardless of the shape, the positive electrode and negative electrode are laminated with a separator in between to form an electrode body, the obtained electrode body is impregnated with a non-aqueous electrolyte, and communicated with the positive electrode current collector to the outside. The positive electrode terminal and the negative electrode current collector and the negative electrode terminal communicating with the outside are connected using a current collecting lead or the like and sealed in a battery case to complete a lithium ion secondary battery.
（ｆ）特性
本発明の正極活物質を用いたリチウムイオン二次電池は、高容量で高出力となる。
特に、より好ましい形態で得られた本発明による正極活物質を用いたリチウムイオン二次電池は、例えば、図１のような２０３２型コイン電池の正極に用いた場合、約２００ｍＡｈ／ｇ以上の高い初期放電容量と低い正極抵抗が得られ、高容量と高出力を両立するものである。さらに、熱安定性が高く、安全性においても優れているといえる。
(f) Characteristics A lithium ion secondary battery using the positive electrode active material of the present invention has high capacity and high output.
In particular, when a lithium ion secondary battery using the positive electrode active material according to the present invention obtained in a more preferable form is used as the positive electrode of a 2032 type coin battery as shown in FIG. The initial discharge capacity and low positive electrode resistance are obtained, and both high capacity and high output are achieved. Furthermore, it has high thermal stability and can be said to be excellent in safety.
なお、本発明における正極抵抗の測定方法を例示すれば、次のようになる。
電気化学的評価手法として一般的な交流インピーダンス法にて電池反応の周波数依存性について測定を行うと、溶液抵抗、負極抵抗と負極容量、及び正極抵抗と正極容量に基づくナイキスト線図が図２のように得られる。
電極における電池反応は、電荷移動に伴う抵抗成分と電気二重層による容量成分とからなり、これらを電気回路で表すと抵抗と容量の並列回路となり、電池全体としては溶液抵抗と負極、正極の並列回路を直列に接続した等価回路で表される。
An example of the method for measuring positive electrode resistance in the present invention is as follows.
When the frequency dependence of the battery reaction is measured using the alternating current impedance method, which is a common electrochemical evaluation method, the Nyquist diagram based on the solution resistance, negative electrode resistance and negative electrode capacity, and positive electrode resistance and positive electrode capacity is shown in Figure 2. obtained as follows.
The battery reaction at the electrode consists of a resistance component due to charge transfer and a capacitance component due to the electric double layer.If these are represented as an electrical circuit, it becomes a parallel circuit of resistance and capacitance.The battery as a whole consists of a parallel circuit of solution resistance, negative electrode, and positive electrode. Represented by an equivalent circuit in which circuits are connected in series.
この等価回路を用いて測定したナイキスト線図に対してフィッティング計算を行い、各抵抗成分、容量成分を見積もることができる。
正極抵抗は、得られるナイキスト線図の低周波数側の半円の直径と等しい。
以上のことから、作製される正極について、交流インピーダンス測定を行い、得られたナイキスト線図に対し等価回路でフィッティング計算することで、正極抵抗を見積もることができる。
本発明により得られた正極活物質を用いた正極を有する二次電池について、その性能（初期放電容量、正極抵抗、サイクル特性）を測定した。
以下、本発明の実施例を用いて具体的に説明するが、本発明は、これらの実施例によって何ら限定されるものではない。
A fitting calculation is performed on the Nyquist diagram measured using this equivalent circuit, and each resistance component and capacitance component can be estimated.
The positive electrode resistance is equal to the diameter of the semicircle on the low frequency side of the obtained Nyquist diagram.
From the above, the positive electrode resistance can be estimated by measuring the alternating current impedance of the manufactured positive electrode and performing a fitting calculation using an equivalent circuit to the obtained Nyquist diagram.
The performance (initial discharge capacity, positive electrode resistance, cycle characteristics) of a secondary battery having a positive electrode using the positive electrode active material obtained according to the present invention was measured.
Hereinafter, the present invention will be specifically explained using examples, but the present invention is not limited to these examples in any way.
（電池の製造及び評価）
正極活物質の評価には、図１に示す２０３２型コイン電池１（以下、コイン型電池と称す）を使用した。
図１に示すように、コイン型電池１は、ケース２と、このケース２内に収容された電極３とから構成されている。
ケース２は、中空かつ一端が開口された正極缶２ａと、この正極缶２ａの開口部に配置される負極缶２ｂとを有しており、負極缶２ｂを正極缶２ａの開口部に配置すると、負極缶２ｂと正極缶２ａとの間に電極３を収容する空間が形成されるように構成されている。
電極３は、正極３ａ、セパレータ３ｃ及び負極３ｂとからなり、この順で並ぶように積層されており、正極３ａが正極缶２ａの内面に接触し、負極３ｂが負極缶２ｂの内面に接触するようにケース２に収容されている。
なお、ケース２はガスケット２ｃを備えており、このガスケット２ｃによって、正極缶２ａと負極缶２ｂとの間が非接触の状態を維持するように相対的な移動が固定されている。また、ガスケット２ｃは、正極缶２ａと負極缶２ｂとの隙間を密封してケース２内と外部との間を気密・液密に遮断する機能も有している。
(Battery manufacturing and evaluation)
A 2032 type coin battery 1 (hereinafter referred to as a coin battery) shown in FIG. 1 was used to evaluate the positive electrode active material.
As shown in FIG. 1, a coin-type battery 1 includes a
The
The
Note that the
図１に示すコイン型電池１は、以下のようにして製作した。
まず、リチウムイオン二次電池用正極活物質５２．５ｍｇ、アセチレンブラック１５ｍｇ、及びポリテトラフッ化エチレン樹脂（ＰＴＦＥ）７．５ｍｇを混合し、１００ＭＰａの圧力で直径１１ｍｍ、厚さ１００μｍにプレス成形して、正極３ａを作製した。作製した正極３ａを真空乾燥機中１２０℃で１２時間乾燥した。
この正極３ａと、負極３ｂ、セパレータ３ｃ及び電解液とを用いて、図１に示すコイン型電池１を、露点が－８０℃に管理されたＡｒ雰囲気のグローブボックス内で作製した。
なお、負極３ｂには、直径１４ｍｍの円盤状に打ち抜かれた平均粒径２０μｍ程度の黒鉛粉末とポリフッ化ビニリデンが銅箔に塗布された負極シートを用いた。
セパレータ３ｃには膜厚２５μｍのポリエチレン多孔膜を用いた。電解液には、１ＭのＬｉＣｌＯ４を支持電解質とするエチレンカーボネート（ＥＣ）とジエチルカーボネート（ＤＥＣ）の等量混合液（富山薬品工業株式会社製）を用いた。
The coin-type battery 1 shown in FIG. 1 was manufactured as follows.
First, 52.5 mg of a positive electrode active material for a lithium ion secondary battery, 15 mg of acetylene black, and 7.5 mg of polytetrafluoroethylene resin (PTFE) were mixed and press-molded at a pressure of 100 MPa to a diameter of 11 mm and a thickness of 100 μm. A positive electrode 3a was produced. The produced positive electrode 3a was dried in a vacuum dryer at 120° C. for 12 hours.
Using this positive electrode 3a,
As the
A polyethylene porous film with a film thickness of 25 μm was used as the
製造したコイン型電池１の性能を示す初期放電容量、正極抵抗は、以下のように評価した。
初期放電容量は、コイン型電池１を製作してから２４時間程度放置し、開回路電圧ＯＣＶ（Ｏｐｅｎ Ｃｉｒｃｕｉｔ Ｖｏｌｔａｇｅ）が安定した後、正極に対する電流密度を０．１ｍＡ／ｃｍ２としてカットオフ電圧４．３Ｖまで充電し、１時間の休止後、カットオフ電圧３．０Ｖまで放電したときの容量を初期放電容量とした。
The initial discharge capacity and positive electrode resistance, which indicate the performance of the manufactured coin-type battery 1, were evaluated as follows.
The initial discharge capacity is determined by setting the current density to the positive electrode at 0.1 mA/cm 2 and setting the cutoff voltage at 4 after leaving the coin-type battery 1 for about 24 hours and stabilizing the open circuit voltage OCV (Open Circuit Voltage). The initial discharge capacity was defined as the capacity when the battery was charged to .3V, and then discharged to a cutoff voltage of 3.0V after a 1-hour rest.
正極抵抗は、コイン型電池１を充電電位４．１Ｖで充電して、周波数応答アナライザ及びポテンショガルバノスタット（ソーラトロン社製、１２５５Ｂ）を使用して交流インピーダンス法により測定すると、図２に示すナイキストプロットが得られる。
このナイキストプロットは、溶液抵抗、負極抵抗とその容量、及び、正極抵抗とその容量を示す特性曲線の和として表しているため、このナイキストプロットに基づき等価回路を用いてフィッティング計算を行い、正極抵抗の値を算出した。
なお、本実施例では、複合水酸化物製造、正極活物質及び二次電池の作製には、和光純薬工業株式会社製試薬特級の各試料を使用した。
The positive electrode resistance is measured by the AC impedance method using a frequency response analyzer and a potentiogalvanostat (Solartron, 1255B) after charging the coin-type battery 1 at a charging potential of 4.1V, and the Nyquist plot shown in FIG. 2 is obtained. is obtained.
This Nyquist plot is expressed as the sum of characteristic curves showing the solution resistance, the negative electrode resistance and its capacity, and the positive electrode resistance and its capacity, so based on this Nyquist plot, a fitting calculation is performed using an equivalent circuit, and the positive electrode resistance is The value of was calculated.
In this example, each sample of reagent special grade manufactured by Wako Pure Chemical Industries, Ltd. was used for the production of the composite hydroxide, the positive electrode active material, and the secondary battery.
以下、実施例を用いて本発明を詳述する。 Hereinafter, the present invention will be explained in detail using Examples.
ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したニッケル複合水酸化物を用意した。このニッケル複合水酸化物のレーザー回折散乱法測定による体積基準の平均粒径ＭＶは１４μｍであった。なお、このニッケル複合水酸化物は、公知の晶析法により得られたものである。 A nickel composite hydroxide in which nickel, cobalt, and aluminum were dissolved in a solid solution at a molar ratio of 91:6:3 was prepared. The volume-based average particle diameter MV of this nickel composite hydroxide was 14 μm as measured by laser diffraction scattering method. Note that this nickel composite hydroxide was obtained by a known crystallization method.
このニッケル複合水酸化物を、大気雰囲気中、６００℃で酸化焙焼してニッケル複合酸化物とした後、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．０１６となるように、ニッケル複合酸化物とリチウム化合物を秤量し混合して、混合粉末を得た。
この混合粉末を、内寸が３０１ｍｍ（Ｌ）×３０１ｍｍ（Ｗ）×１０２ｍｍ（Ｈ）の焼成容器に６ｋｇ装入し、これを雰囲気制御可能なバッチ式電気炉を用いて、酸素濃度８０容量％の雰囲気中で、９時間かけて７４５℃まで昇温し、７４５℃で３時間キープした。その後、室温まで炉内で冷却した後に焼成物を回収した。この時、混合物の昇温開始から回収までに要した時間（焼成開始から冷却完了までの時間）は、２０時間以内であった。焼成物の解砕処理を行い、一次粒子が凝集した球状焼成粉末を得た。
This nickel composite hydroxide was oxidized and roasted at 600°C in the air to form a nickel composite oxide, and the molar ratio was Ni:Co:Al:Li=0.91:0.06:0.03. :1.016, the nickel composite oxide and the lithium compound were weighed and mixed to obtain a mixed powder.
6 kg of this mixed powder was charged into a firing container with internal dimensions of 301 mm (L) x 301 mm (W) x 102 mm (H), and was heated to an oxygen concentration of 80% by volume using a batch-type electric furnace capable of controlling the atmosphere. In this atmosphere, the temperature was raised to 745°C over 9 hours and kept at 745°C for 3 hours. Thereafter, the fired product was collected after being cooled to room temperature in the furnace. At this time, the time required from the start of heating the mixture to recovery (time from the start of firing to the completion of cooling) was within 20 hours. The fired product was crushed to obtain a spherical fired powder in which primary particles were aggregated.
得られた焼成物を、質量比で水１に対し０．７５となるように、純水に投入してスラリーとし、３０分間の撹拌後、濾過、乾燥してリチウムニッケル複合酸化物を得た。
その得られたリチウムニッケル複合酸化物について、ＩＣＰ発光分光分析器（ＶＡＲＩＡＮ社製、７２５ＥＳ）を用いた定量分析により、リチウム遷移金属複合酸化物は、Ｌｉ、Ｎｉ、Ｃｏ、Ａｌの物質量比が、Ｌｉ：Ｎｉ：Ｃｏ：Ａｌ＝１．０１６：０．９１：０．０６：０．０３で表されるものであることを確認した。また、ＸＲＤ（ＰＡＮＡＬＹＴＩＣＡＬ社製、Ｘ‘Ｐｅｒｔ、ＰＲＯＭＲＤ）を用いて測定したＸＲＤチャートより、Ｒｉｅｔｖｅｌｄ解析法を用いてｃ軸の長さであるｃ軸の格子定数を求めた。
The obtained fired product was poured into pure water to make a slurry at a mass ratio of 0.75 to 1 water, and after stirring for 30 minutes, it was filtered and dried to obtain a lithium-nickel composite oxide. .
Quantitative analysis of the obtained lithium-nickel composite oxide using an ICP emission spectrometer (manufactured by VARIAN, 725ES) revealed that the lithium-transition metal composite oxide has a material ratio of Li, Ni, Co, and Al. , Li:Ni:Co:Al=1.016:0.91:0.06:0.03. Further, from the XRD chart measured using XRD (PANALYTICAL, X'Pert, PROMRD), the c-axis lattice constant, which is the length of the c-axis, was determined using the Rietveld analysis method.
［電池評価］
得られた正極活物質を使用して作製された正極を有する図１に示すコイン型電池１の電池特性を評価した。初期充電容量は２３２ｍＡｈ／ｇ、初期放電容量は２０５．６ｍＡｈ／ｇ、初期充放電効率８８．７％であった。
以下、実施例及び比較例については、実施例１と変更した物質、条件のみを示す。
また、初期放電容量の他に、正極抵抗の評価値を合わせて表１に示す。
[Battery evaluation]
The battery characteristics of the coin-type battery 1 shown in FIG. 1 having a positive electrode manufactured using the obtained positive electrode active material were evaluated. The initial charging capacity was 232 mAh/g, the initial discharging capacity was 205.6 mAh/g, and the initial charging/discharging efficiency was 88.7%.
Hereinafter, in Examples and Comparative Examples, only substances and conditions that were changed from Example 1 will be shown.
In addition to the initial discharge capacity, the evaluation values of the positive electrode resistance are also shown in Table 1.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．０２４となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:6:3 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. A positive electrode active material was obtained in the same manner as in Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 06:0.03:1.024.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．０４０となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:6:3 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. A positive electrode active material was obtained in the same manner as in Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed in a ratio of 06:0.03:1.040.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．０１８となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと、混合粉末の最高到達温度を７６０℃で焼成を行ったこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:6:3 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. Same as Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 06:0.03:1.018, and the mixed powder was fired at a maximum temperature of 760 ° C. A positive electrode active material was obtained.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．０１７となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと、混合粉末の最高到達温度を７１５℃で焼成を行ったこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:6:3 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. Same as Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 06:0.03:1.017, and the mixed powder was fired at a maximum temperature of 715 ° C. A positive electrode active material was obtained.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：３：６で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０３：０．０６：１．０１８となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:3:6 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. A positive electrode active material was obtained in the same manner as in Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 03:0.06:1.018.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：５：４で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０５：０．０４：１．０１７となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:5:4 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. A positive electrode active material was obtained in the same manner as in Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 05:0.04:1.017.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が８８：９：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．８８：０．０９：０．０３：１．０２５となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと、混合粉末の最高到達温度を７６０℃で焼成を行ったこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 88:9:3 was used, and the molar ratio of Ni:Co:Al:Li=0.88:0. Same as Example 1 except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 09:0.03:1.025, and that the mixed powder was fired at a maximum temperature of 760 ° C. A positive electrode active material was obtained.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９４：３９：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９４：０．３９：０．０３：１．０１５となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 94:39:3 was used, and the molar ratio of Ni:Co:Al:Li=0.94:0. A positive electrode active material was obtained in the same manner as in Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed in a ratio of 39:0.03:1.015.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、Ｍ元素をＡｌ以外にＭｎを含み、ニッケルとコバルトとアルミニウムとマンガンのモル比が９１：６：２：１で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｍｎ：Ｌｉ＝０．９１：０．０６：０．０２：０．０１：１．０１７となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, the M element was used that contained Mn in addition to Al, and the molar ratio of nickel, cobalt, aluminum, and manganese was 91:6:2:1. Except for weighing and mixing the nickel composite oxide and lithium compound so that Ni:Co:Al:Mn:Li=0.91:0.06:0.02:0.01:1.017. A positive electrode active material was obtained in the same manner as in Example 1.
Table 1 shows the evaluation results of battery characteristics.
ニッケル複合水酸化物として、Ｍ元素をＡｌ以外にＷを含み、ニッケルとコバルトとアルミニウムとタングステンのモル比が９１：６：２：１で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｗ：Ｌｉ＝０．９１：０．０６：０．０２：０．０１：１．０１７となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
As the nickel composite hydroxide, the M element was used as a solid solution containing W in addition to Al, and the molar ratio of nickel, cobalt, aluminum, and tungsten was 91:6:2:1, and Except that the nickel composite oxide and lithium compound were weighed and mixed so that Ni:Co:Al:W:Li=0.91:0.06:0.02:0.01:1.017. A positive electrode active material was obtained in the same manner as in Example 1.
Table 1 shows the evaluation results of battery characteristics.
（比較例１）
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．０１４となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと、混合粉末の最高到達温度を７００℃で焼成を行ったこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
(Comparative example 1)
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:6:3 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. Same as Example 1 except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 06:0.03:1.014, and that the mixed powder was fired at a maximum temperature of 700 ° C. A positive electrode active material was obtained.
Table 1 shows the evaluation results of battery characteristics.
（比較例２）
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．０１５となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと、混合粉末の最高到達温度を７８０℃で焼成を行ったこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
(Comparative example 2)
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:6:3 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. Same as Example 1 except that the nickel composite oxide and lithium compound were weighed and mixed so that the ratio was 06:0.03:1.015, and that the mixed powder was fired at a maximum temperature of 780 ° C. A positive electrode active material was obtained.
Table 1 shows the evaluation results of battery characteristics.
（比較例３）
ニッケル複合水酸化物として、ニッケルとコバルトとアルミニウムのモル比が９１：６：３で固溶したものを使用したこと、および、モル比でＮｉ：Ｃｏ：Ａｌ：Ｌｉ＝０．９１：０．０６：０．０３：１．１５０となるようにニッケル複合酸化物とリチウム化合物を秤量し混合したこと以外は、実施例１と同様にして正極活物質を得た。
電池特性の評価結果を、表１に示す。
(Comparative example 3)
As the nickel composite hydroxide, a solid solution of nickel, cobalt, and aluminum with a molar ratio of 91:6:3 was used, and the molar ratio of Ni:Co:Al:Li=0.91:0. A positive electrode active material was obtained in the same manner as in Example 1, except that the nickel composite oxide and lithium compound were weighed and mixed in a ratio of 06:0.03:1.150.
Table 1 shows the evaluation results of battery characteristics.
［評価］
表１から明らかなように、実施例１～１１の正極活物質は、Ｘ線回折測定の結果得られたｃ軸の格子定数が、βの算出式：β＝０．０００４３４７α＋１．４２０１－０．０２×（ｘ＋ｙ）により求められる値よりも小さいこと（β－ｃ軸の格子定数＞０）から、複合元素、実施例１から９ではＡｌの溶出が抑えられており、かつ優れた電池特性を有している。また、実施１０、１１では複合元素をＡｌの他にＭｎ或いはＷを含む場合にも、複合元素の溶出が抑えられ優れた電池特性を示している。
[evaluation]
As is clear from Table 1, the positive electrode active materials of Examples 1 to 11 have c-axis lattice constants obtained as a result of X-ray diffraction measurements using the formula for calculating β: β=0.0004347α+1.4201-0. Since the value is smaller than the value determined by have. Further, in Examples 10 and 11, even when the composite element contained Mn or W in addition to Al, the elution of the composite element was suppressed and excellent battery characteristics were exhibited.
実施例１～３では、水洗前組成におけるＬｉの割合が高いほど、複合元素のメタル比が小さく、ｃ軸の格子定数が小さくなっており、かつ初期放電容量や初期充放電効率が優れている。 In Examples 1 to 3, the higher the proportion of Li in the composition before water washing, the smaller the metal ratio of the composite element, the smaller the c-axis lattice constant, and the better the initial discharge capacity and initial charge/discharge efficiency. .
実施例１、４、５では、焼成温度高いほど複合元素のメタル比が小さく、ｃ軸の長さが小さくなっている。
実施例６、７では、複合電素であるＡｌの比率が増えるに従い、ｃ軸の長さが大きくなっている。
実施例８、９では、Ｎｉの比率が増えるに従い、ｃ軸の長さが大きくなっている。
In Examples 1, 4, and 5, the higher the firing temperature, the smaller the metal ratio of the composite element and the smaller the c-axis length.
In Examples 6 and 7, as the ratio of Al, which is a composite element, increases, the length of the c-axis increases.
In Examples 8 and 9, the length of the c-axis increases as the Ni ratio increases.
比較例１では、ｃ軸の長さβを、上記式（１）により求め、測定して得たｃ軸の長さ（ｃ軸格子定数）よりも大きい（β－ｃ軸の長さ＞０）が、焼成温度が低いため結晶子径が１００ｎｍ以下になっており、このような正極活物質では正極抵抗（反応抵抗）が大きくなり、電池特性の劣化がみられる。 In Comparative Example 1, the c-axis length β was determined by the above formula (1) and was larger than the measured c-axis length (c-axis lattice constant) (β - c-axis length > 0). ), the crystallite diameter is 100 nm or less due to the low firing temperature, and such positive electrode active materials have increased positive electrode resistance (reaction resistance) and deterioration of battery characteristics.
比較例２では、焼成温度が高いためにｃ軸の長さが、上記式（１）より得られるβの値よりも大きいため（β－ｃ軸長さ＜０）、Ａｌの溶出量が多く、サイクル特性や熱安定性が劣化すると思われる。 In Comparative Example 2, the c-axis length was larger than the value of β obtained from the above formula (1) due to the high firing temperature (β-c-axis length < 0), so the amount of Al eluted was large. , cycle characteristics and thermal stability are likely to deteriorate.
比較例３でも、水洗前のＬｉ組成比が１．１０以上であるためにｃ軸の長さが、上式（１）により求められるβの値より大きいため（β－ｃ軸の長さ＜０）、Ａｌの溶出量が多く、サイクル特性や熱安定性が劣化すると思われる。 Also in Comparative Example 3, since the Li composition ratio before water washing is 1.10 or more, the length of the c-axis is larger than the value of β determined by the above formula (1) (β-length of the c-axis < 0), the amount of Al eluted is large, and the cycle characteristics and thermal stability are thought to deteriorate.
実施例１～９、及び比較例１～３で得られた正極活物質における、複合元素のメタル比：αと、ｃ軸の長さの関係を図３に示す。
図３中の実線は、上記（１）式における「β」の線形関係を示すもので、実施例１～９は全て実線より下方に位置し、比較例では、比較例１を除き、実線の上方に位置した結果となっている。
FIG. 3 shows the relationship between the metal ratio of the composite element: α and the length of the c-axis in the positive electrode active materials obtained in Examples 1 to 9 and Comparative Examples 1 to 3.
The solid line in FIG. 3 shows the linear relationship of "β" in the above equation (1). Examples 1 to 9 are all located below the solid line, and the comparative examples, except for comparative example 1, are below the solid line. As a result, it is located above.
電気自動車用の電源としてリチウムイオン二次電池が普及するためには電池の低コスト化が不可欠であるが、量産性に優れるという本発明の正極活物質を用いることで低コスト化が可能となり、その工業的価値は極めて大きいといえる。なお、電気自動車用の電源とは、純粋に電気エネルギーで駆動する電気自動車のみならず、ガソリンエンジン、ディーゼルエンジンなどの燃焼機関と併用する、いわゆるハイブリッド車の電源として用いることをも含む。 In order for lithium ion secondary batteries to become popular as a power source for electric vehicles, it is essential to reduce the cost of batteries, but by using the positive electrode active material of the present invention, which has excellent mass production, it is possible to reduce costs. Its industrial value can be said to be extremely large. Note that a power source for an electric vehicle includes not only an electric vehicle driven purely by electric energy, but also a power source for a so-called hybrid vehicle that is used in combination with a combustion engine such as a gasoline engine or a diesel engine.
１ コイン型電池
２ ケース
２ａ 正極缶
２ｂ 負極缶
２ｃ ガスケット
３ 電極
３ａ 正極
３ｂ 負極
３ｃ セパレータ
1 Coin-
Claims (2)
前記リチウムニッケル複合酸化物のＸ線回折測定から得られた（００３）面回折ピークの半価幅を用いてＳｃｈｅｒｒｅｒ式により求めた結晶子径が、１００ｎｍ以上、１６０ｎｍ以下であり、
前記Ｘ線回折測定結果からリートベルト解析を行なって求めた「３ａサイト」におけるリチウムの席占有率が、９７％以上であり、
前記リチウムニッケル複合酸化物のＮｉとＣｏの物質量の和に対するＭの物質量の比［ｍＭ／（ｍＮｉ＋ｍＣｏ）］の百分率表示をα［％］とした時に、
下記式（１）より求められる数値βよりも、ｃ軸格子定数（単位：ｎｍ）が小さいリチウムニッケル複合酸化物であることを特徴とするリチウムイオン二次電池用正極活物質。
The crystallite diameter determined by the Scherrer equation using the half width of the (003) plane diffraction peak obtained from the X-ray diffraction measurement of the lithium nickel composite oxide is 100 nm or more and 160 nm or less,
The lithium seat occupancy rate at the "3a site" determined by Rietveld analysis from the X-ray diffraction measurement results is 97% or more,
When the ratio of the amount of M to the sum of the amounts of Ni and Co in the lithium-nickel composite oxide [m M /(m Ni + m Co )] is expressed as a percentage, α [%] is:
A positive electrode active material for a lithium ion secondary battery, characterized in that it is a lithium-nickel composite oxide having a c-axis lattice constant (unit: nm) smaller than the numerical value β determined by the following formula (1).
少なくともニッケルとコバルトを含み、ニッケルとコバルトおよび添加元素Ｍ（ＭはＡｌ、又はＡｌとＭｎ、Ｖ、Ｍｇ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉから選ばれる少なくとも１種の元素からなる）の物質量比Ｎｉ：Ｃｏ：Ｍが１－ｘ－ｙ：ｘ：ｙであるニッケル化合物と、リチウム化合物とを混合して原料混合物を得る混合工程と、
前記原料混合物を、酸素濃度が８０容量％以上の雰囲気中で、前記原料混合物の最高温度が７１５℃以上、７６５℃以下で、加熱開始から最高温度への到達およびその保持を経由して冷却が完了するまでの工程全体の時間である焼成時間は、８時間以上、２０時間以下となるように焼成してリチウムニッケル複合酸化物の焼成粉末を得る焼成工程と、
前記リチウムニッケル複合酸化物の焼成粉末、７００ｇ以上、１２００ｇ以下を水と混合して１Ｌのスラリーとし、該スラリーのスラリー温度を１０℃以上、４０℃以下に維持しつつ、１０分以上、１時間以内で撹拌して前記リチウムニッケル複合酸化物を水洗処理した後、濾過、乾燥してリチウムニッケル複合酸化物粉末を得る水洗工程と、
を含むことを特徴とするリチウムイオン二次電池用正極活物質の製造方法。 A method for producing a positive electrode active material for a lithium ion secondary battery according to claim 1 ,
Contains at least nickel and cobalt, and the substance amount ratio of nickel, cobalt, and additional element M (M consists of Al, or Al and at least one element selected from Mn, V, Mg, W, Mo, Nb, and Ti) A mixing step of obtaining a raw material mixture by mixing a nickel compound in which Ni:Co:M is 1-xy:x:y and a lithium compound;
The raw material mixture is cooled in an atmosphere with an oxygen concentration of 80% by volume or more, at a maximum temperature of 715°C or more and 765°C or less , from the start of heating to reaching the maximum temperature and maintaining it. A firing step in which a fired powder of lithium-nickel composite oxide is obtained by firing so that the firing time, which is the time for the entire process to complete, is 8 hours or more and 20 hours or less ;
Mix 700 g or more and 1200 g or less of the fired powder of the lithium-nickel composite oxide with water to make 1 L of slurry, and maintain the slurry temperature at 10° C. or more and 40° C. or less for 10 minutes or more and 1 hour. a washing step of washing the lithium nickel composite oxide with water, filtering and drying the lithium nickel composite oxide to obtain a lithium nickel composite oxide powder;
A method for producing a positive electrode active material for a lithium ion secondary battery, the method comprising:
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| WO2014010448A1 (en) | 2012-07-12 | 2014-01-16 | 住友金属鉱山株式会社 | Positive electrode active substance for nonaqueous electrolyte secondary cell, method for producing same, and nonaqueous electrolyte secondary cell using positive electrode active substance |
| WO2015008582A1 (en) | 2013-07-17 | 2015-01-22 | 住友金属鉱山株式会社 | Positive-electrode active material for non-aqueous electrolyte secondary battery, method for producing said positive-electrode active material for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery using said positive-electrode active material for non-aqueous electrolyte secondary battery |
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| WO2015008582A1 (en) | 2013-07-17 | 2015-01-22 | 住友金属鉱山株式会社 | Positive-electrode active material for non-aqueous electrolyte secondary battery, method for producing said positive-electrode active material for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery using said positive-electrode active material for non-aqueous electrolyte secondary battery |
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