WO2006109930A1 - Cathode active material coated with fluorine compound for lithium secondary batteries and method for preparing the same - Google Patents
Cathode active material coated with fluorine compound for lithium secondary batteries and method for preparing the same Download PDFInfo
- Publication number
- WO2006109930A1 WO2006109930A1 PCT/KR2006/000987 KR2006000987W WO2006109930A1 WO 2006109930 A1 WO2006109930 A1 WO 2006109930A1 KR 2006000987 W KR2006000987 W KR 2006000987W WO 2006109930 A1 WO2006109930 A1 WO 2006109930A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- active material
- cathode active
- fluorine compound
- coated
- fluorine
- Prior art date
Links
- 239000006182 cathode active material Substances 0.000 title claims abstract description 146
- 150000002222 fluorine compounds Chemical class 0.000 title claims abstract description 63
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 62
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims description 35
- 229910052731 fluorine Inorganic materials 0.000 claims description 30
- 150000001875 compounds Chemical class 0.000 claims description 21
- 239000011737 fluorine Substances 0.000 claims description 20
- 239000000243 solution Substances 0.000 claims description 20
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 19
- 229910052782 aluminium Inorganic materials 0.000 claims description 19
- 229910052749 magnesium Inorganic materials 0.000 claims description 19
- 229910052751 metal Inorganic materials 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 19
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical group [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 16
- 229910052804 chromium Inorganic materials 0.000 claims description 16
- 239000002243 precursor Substances 0.000 claims description 16
- 229910052725 zinc Inorganic materials 0.000 claims description 16
- 229910052759 nickel Inorganic materials 0.000 claims description 14
- 239000011259 mixed solution Substances 0.000 claims description 13
- 229910052719 titanium Inorganic materials 0.000 claims description 13
- 239000007864 aqueous solution Substances 0.000 claims description 12
- 229910052791 calcium Inorganic materials 0.000 claims description 12
- 229910052748 manganese Inorganic materials 0.000 claims description 12
- 229910052721 tungsten Inorganic materials 0.000 claims description 12
- 229910017709 Ni Co Inorganic materials 0.000 claims description 11
- 239000006185 dispersion Substances 0.000 claims description 10
- 239000000843 powder Substances 0.000 claims description 10
- 229910052718 tin Inorganic materials 0.000 claims description 9
- -1 Hg^ Chemical compound 0.000 claims description 8
- 229910052796 boron Inorganic materials 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims description 8
- 229910052700 potassium Inorganic materials 0.000 claims description 6
- KWVVTSALYXIJSS-UHFFFAOYSA-L silver(ii) fluoride Chemical compound [F-].[F-].[Ag+2] KWVVTSALYXIJSS-UHFFFAOYSA-L 0.000 claims description 6
- 229910052708 sodium Inorganic materials 0.000 claims description 6
- 238000000137 annealing Methods 0.000 claims description 5
- 229910052710 silicon Inorganic materials 0.000 claims description 5
- 229910052596 spinel Inorganic materials 0.000 claims description 5
- 239000011029 spinel Substances 0.000 claims description 5
- 229910052720 vanadium Inorganic materials 0.000 claims description 5
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 4
- 229910016569 AlF 3 Inorganic materials 0.000 claims description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 4
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 4
- 229910052693 Europium Inorganic materials 0.000 claims description 4
- 229910052765 Lutetium Inorganic materials 0.000 claims description 4
- 229910002651 NO3 Inorganic materials 0.000 claims description 4
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 4
- 229910052771 Terbium Inorganic materials 0.000 claims description 4
- 229910052775 Thulium Inorganic materials 0.000 claims description 4
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 4
- 150000004703 alkoxides Chemical group 0.000 claims description 4
- 229910052787 antimony Inorganic materials 0.000 claims description 4
- 229910052788 barium Inorganic materials 0.000 claims description 4
- 229910052797 bismuth Inorganic materials 0.000 claims description 4
- 229910052793 cadmium Inorganic materials 0.000 claims description 4
- 229910052792 caesium Inorganic materials 0.000 claims description 4
- 229910052738 indium Inorganic materials 0.000 claims description 4
- 229910052746 lanthanum Inorganic materials 0.000 claims description 4
- 229910052745 lead Inorganic materials 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 229910052702 rhenium Inorganic materials 0.000 claims description 4
- 229910052701 rubidium Inorganic materials 0.000 claims description 4
- 229910052709 silver Inorganic materials 0.000 claims description 4
- 229910052712 strontium Inorganic materials 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 229910052724 xenon 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
- 229910021594 Copper(II) fluoride Inorganic materials 0.000 claims description 3
- 229910016468 DyF3 Inorganic materials 0.000 claims description 3
- 229910016653 EuF3 Inorganic materials 0.000 claims description 3
- 229910005270 GaF3 Inorganic materials 0.000 claims description 3
- 229910005693 GdF3 Inorganic materials 0.000 claims description 3
- 229910004650 HoF3 Inorganic materials 0.000 claims description 3
- 229910021620 Indium(III) fluoride Inorganic materials 0.000 claims description 3
- 229910002319 LaF3 Inorganic materials 0.000 claims description 3
- 229910013482 LuF3 Inorganic materials 0.000 claims description 3
- 229910021570 Manganese(II) fluoride Inorganic materials 0.000 claims description 3
- 229910021571 Manganese(III) fluoride Inorganic materials 0.000 claims description 3
- 229910017557 NdF3 Inorganic materials 0.000 claims description 3
- 229910019322 PrF3 Inorganic materials 0.000 claims description 3
- 229910018096 ScF3 Inorganic materials 0.000 claims description 3
- 229910021608 Silver(I) fluoride Inorganic materials 0.000 claims description 3
- 229910021175 SmF3 Inorganic materials 0.000 claims description 3
- 229910004299 TbF3 Inorganic materials 0.000 claims description 3
- 229910010346 TiF Inorganic materials 0.000 claims description 3
- 229910010348 TiF3 Inorganic materials 0.000 claims description 3
- 229910008903 TmF3 Inorganic materials 0.000 claims description 3
- GUNJVIDCYZYFGV-UHFFFAOYSA-K antimony trifluoride Chemical compound F[Sb](F)F GUNJVIDCYZYFGV-UHFFFAOYSA-K 0.000 claims description 3
- 229910001632 barium fluoride Inorganic materials 0.000 claims description 3
- WTEOIRVLGSZEPR-UHFFFAOYSA-N boron trifluoride Chemical compound FB(F)F WTEOIRVLGSZEPR-UHFFFAOYSA-N 0.000 claims description 3
- LVEULQCPJDDSLD-UHFFFAOYSA-L cadmium fluoride Chemical compound F[Cd]F LVEULQCPJDDSLD-UHFFFAOYSA-L 0.000 claims description 3
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 3
- GWFAVIIMQDUCRA-UHFFFAOYSA-L copper(ii) fluoride Chemical compound [F-].[F-].[Cu+2] GWFAVIIMQDUCRA-UHFFFAOYSA-L 0.000 claims description 3
- CTNMMTCXUUFYAP-UHFFFAOYSA-L difluoromanganese Chemical compound F[Mn]F CTNMMTCXUUFYAP-UHFFFAOYSA-L 0.000 claims description 3
- FMSYTQMJOCCCQS-UHFFFAOYSA-L difluoromercury Chemical compound F[Hg]F FMSYTQMJOCCCQS-UHFFFAOYSA-L 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- FZGIHSNZYGFUGM-UHFFFAOYSA-L iron(ii) fluoride Chemical compound [F-].[F-].[Fe+2] FZGIHSNZYGFUGM-UHFFFAOYSA-L 0.000 claims description 3
- SHXXPRJOPFJRHA-UHFFFAOYSA-K iron(iii) fluoride Chemical compound F[Fe](F)F SHXXPRJOPFJRHA-UHFFFAOYSA-K 0.000 claims description 3
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Inorganic materials [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims description 3
- SRVINXWCFNHIQZ-UHFFFAOYSA-K manganese(iii) fluoride Chemical compound [F-].[F-].[F-].[Mn+3] SRVINXWCFNHIQZ-UHFFFAOYSA-K 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 3
- HHQFLEDKAVLHOM-UHFFFAOYSA-N oxovanadium;trihydrofluoride Chemical compound F.F.F.[V]=O HHQFLEDKAVLHOM-UHFFFAOYSA-N 0.000 claims description 3
- AHLATJUETSFVIM-UHFFFAOYSA-M rubidium fluoride Inorganic materials [F-].[Rb+] AHLATJUETSFVIM-UHFFFAOYSA-M 0.000 claims description 3
- OEKDNFRQVZLFBZ-UHFFFAOYSA-K scandium fluoride Chemical compound F[Sc](F)F OEKDNFRQVZLFBZ-UHFFFAOYSA-K 0.000 claims description 3
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Inorganic materials [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 claims description 3
- FDIFPFNHNADKFC-UHFFFAOYSA-K trifluoroholmium Chemical compound F[Ho](F)F FDIFPFNHNADKFC-UHFFFAOYSA-K 0.000 claims description 3
- JNLSTWIBJFIVHZ-UHFFFAOYSA-K trifluoroindigane Chemical compound F[In](F)F JNLSTWIBJFIVHZ-UHFFFAOYSA-K 0.000 claims description 3
- BYMUNNMMXKDFEZ-UHFFFAOYSA-K trifluorolanthanum Chemical compound F[La](F)F BYMUNNMMXKDFEZ-UHFFFAOYSA-K 0.000 claims description 3
- LKNRQYTYDPPUOX-UHFFFAOYSA-K trifluoroterbium Chemical compound F[Tb](F)F LKNRQYTYDPPUOX-UHFFFAOYSA-K 0.000 claims description 3
- 229910019142 PO4 Inorganic materials 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 239000010450 olivine Substances 0.000 claims description 2
- 229910052609 olivine Inorganic materials 0.000 claims description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 2
- 239000010452 phosphate Substances 0.000 claims description 2
- 101100274801 Caenorhabditis elegans dyf-3 gene Proteins 0.000 claims 1
- 229910020186 CeF4 Inorganic materials 0.000 claims 1
- 229910006160 GeF4 Inorganic materials 0.000 claims 1
- 229910004504 HfF4 Inorganic materials 0.000 claims 1
- 229910017698 Ni 1-x-y Co Inorganic materials 0.000 claims 1
- 229910004014 SiF4 Inorganic materials 0.000 claims 1
- 229910008449 SnF 2 Inorganic materials 0.000 claims 1
- 229910009527 YF3 Inorganic materials 0.000 claims 1
- 229910009520 YbF3 Inorganic materials 0.000 claims 1
- ABTOQLMXBSRXSM-UHFFFAOYSA-N silicon tetrafluoride Chemical compound F[Si](F)(F)F ABTOQLMXBSRXSM-UHFFFAOYSA-N 0.000 claims 1
- PPMWWXLUCOODDK-UHFFFAOYSA-N tetrafluorogermane Chemical compound F[Ge](F)(F)F PPMWWXLUCOODDK-UHFFFAOYSA-N 0.000 claims 1
- 229910012820 LiCoO Inorganic materials 0.000 description 33
- 239000011572 manganese Substances 0.000 description 31
- 230000000052 comparative effect Effects 0.000 description 27
- 239000011248 coating agent Substances 0.000 description 21
- 238000000576 coating method Methods 0.000 description 21
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 21
- 238000002441 X-ray diffraction Methods 0.000 description 14
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 11
- 238000000975 co-precipitation Methods 0.000 description 11
- 239000003792 electrolyte Substances 0.000 description 11
- 239000012153 distilled water Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 229910015672 LiMn O Inorganic materials 0.000 description 8
- 230000007423 decrease Effects 0.000 description 8
- 238000000840 electrochemical analysis Methods 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 239000011149 active material Substances 0.000 description 7
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- 229910015643 LiMn 2 O 4 Inorganic materials 0.000 description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 238000004090 dissolution Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminium flouride Chemical compound F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- BHHYHSUAOQUXJK-UHFFFAOYSA-L zinc fluoride Chemical compound F[Zn]F BHHYHSUAOQUXJK-UHFFFAOYSA-L 0.000 description 4
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 3
- 229910017855 NH 4 F Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 150000007513 acids Chemical class 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011244 liquid electrolyte Substances 0.000 description 3
- 229910001512 metal fluoride Inorganic materials 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- POAOYUHQDCAZBD-UHFFFAOYSA-N 2-butoxyethanol Chemical compound CCCCOCCO POAOYUHQDCAZBD-UHFFFAOYSA-N 0.000 description 2
- 229910015900 BF3 Inorganic materials 0.000 description 2
- FIPWRIJSWJWJAI-UHFFFAOYSA-N Butyl carbitol 6-propylpiperonyl ether Chemical compound C1=C(CCC)C(COCCOCCOCCCC)=CC2=C1OCO2 FIPWRIJSWJWJAI-UHFFFAOYSA-N 0.000 description 2
- 229910020187 CeF3 Inorganic materials 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 229910021564 Chromium(III) fluoride Inorganic materials 0.000 description 2
- 229910015645 LiMn Inorganic materials 0.000 description 2
- 229910013292 LiNiO Inorganic materials 0.000 description 2
- 229910001228 Li[Ni1/3Co1/3Mn1/3]O2 (NCM 111) Inorganic materials 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910021587 Nickel(II) fluoride Inorganic materials 0.000 description 2
- 238000001479 atomic absorption spectroscopy Methods 0.000 description 2
- 238000011088 calibration curve Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- FPHIOHCCQGUGKU-UHFFFAOYSA-L difluorolead Chemical compound F[Pb]F FPHIOHCCQGUGKU-UHFFFAOYSA-L 0.000 description 2
- HHFAWKCIHAUFRX-UHFFFAOYSA-N ethoxide Chemical compound CC[O-] HHFAWKCIHAUFRX-UHFFFAOYSA-N 0.000 description 2
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 2
- NBTOZLQBSIZIKS-UHFFFAOYSA-N methoxide Chemical compound [O-]C NBTOZLQBSIZIKS-UHFFFAOYSA-N 0.000 description 2
- DBJLJFTWODWSOF-UHFFFAOYSA-L nickel(ii) fluoride Chemical compound F[Ni]F DBJLJFTWODWSOF-UHFFFAOYSA-L 0.000 description 2
- 229960005235 piperonyl butoxide Drugs 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000005518 polymer electrolyte Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- OGHBATFHNDZKSO-UHFFFAOYSA-N propan-2-olate Chemical compound CC(C)[O-] OGHBATFHNDZKSO-UHFFFAOYSA-N 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- ANOBYBYXJXCGBS-UHFFFAOYSA-L stannous fluoride Chemical compound F[Sn]F ANOBYBYXJXCGBS-UHFFFAOYSA-L 0.000 description 2
- FVRNDBHWWSPNOM-UHFFFAOYSA-L strontium fluoride Chemical compound [F-].[F-].[Sr+2] FVRNDBHWWSPNOM-UHFFFAOYSA-L 0.000 description 2
- 229910001637 strontium fluoride Inorganic materials 0.000 description 2
- FTBATIJJKIIOTP-UHFFFAOYSA-K trifluorochromium Chemical compound F[Cr](F)F FTBATIJJKIIOTP-UHFFFAOYSA-K 0.000 description 2
- IGELFKKMDLGCJO-UHFFFAOYSA-N xenon difluoride Chemical compound F[Xe]F IGELFKKMDLGCJO-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910013733 LiCo Inorganic materials 0.000 description 1
- 229910015679 LiMn 2 O4 Inorganic materials 0.000 description 1
- 229910013553 LiNO Inorganic materials 0.000 description 1
- 229910013290 LiNiO 2 Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- NKCVNYJQLIWBHK-UHFFFAOYSA-N carbonodiperoxoic acid Chemical compound OOC(=O)OO NKCVNYJQLIWBHK-UHFFFAOYSA-N 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000000349 field-emission scanning electron micrograph Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 235000002639 sodium chloride Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G45/00—Compounds of manganese
- C01G45/12—Manganates manganites or permanganates
- C01G45/1221—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof
- C01G45/1242—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof of the type [Mn2O4]-, e.g. LiMn2O4, Li[MxMn2-x]O4
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G51/00—Compounds of cobalt
- C01G51/40—Cobaltates
- C01G51/42—Cobaltates containing alkali metals, e.g. LiCoO2
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G51/00—Compounds of cobalt
- C01G51/40—Cobaltates
- C01G51/42—Cobaltates containing alkali metals, e.g. LiCoO2
- C01G51/44—Cobaltates containing alkali metals, e.g. LiCoO2 containing manganese
- C01G51/50—Cobaltates containing alkali metals, e.g. LiCoO2 containing manganese of the type [MnO2]n-, e.g. Li(CoxMn1-x)O2, Li(MyCoxMn1-x-y)O2
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/40—Nickelates
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Definitions
- the present invention relates to a method for treating the surface of a cathode active material for lithium secondary batteries with superior cycle characteristics and excellent high-rate characteristics. More particularly, the present invention relates to an improvement in the charge-discharge characteristics, cycle characteristics, high-voltage characteristics and thermal stability of lithium secondary batteries by coating a cathode active material for the lithium secondary batteries with a fluorine compound.
- Lithium secondary batteries are classified into lithium metal batteries using lithium as an anode and lithium ion batteries using an interlayer compound, e.g., carbon, capable of intercalation/deintercalation of lithium ions. Further, lithium secondary batteries are classified into liquid type batteries using a liquid electrolyte, gel type polymer batteries using a mixture of liquid and polymer electrolytes, and solid type polymer batteries using a pure polymer electrolyte according to the kind of electrolytes used.
- LiCoO LiCoO
- carbon LiMn O
- LiCoO 2 LiCo x Ni 1-x O 2
- LiMn 2 O 4 LiCoO 2 is a promising material in terms of its stable charge-discharge char- acteristics, high electronic conductivity, superior thermal stability and constant discharge voltage characteristics, but has disadvantages of insufficient cobalt deposits, high price and toxicity.
- LiNiO has problems that it is difficult to synthesize and is thermally unstable, which make LiNiO unsuitable for commercialization.
- Commercial applications of LiMn 2 O 4 are currently limited to some low-priced products.
- LiMn 2 O 4 is has a spinel structure and deliverers a lower theoretical capacity (-148 mAh/g) than other active materials.
- LiMn 2 O 4 has poor cycle characteristics due to the Mn dissolution into electrolyte. Particularly, since LiMn O has poor high-temperature characteristics at 55°C or higher when compared to LiCoO , it has not yet been put to practical use in batteries.
- Li[Ni Mn ]O is extremely low, which causes difficulty in the commercialization of the material (J. of Power Sources, ' 112 ( V 2002) ' 41-48) '.
- LiCoO 2 and LiMn 2 O 4 show poor high-power characteristics over LiCoO 2 and LiMn 2 O 4 , which makes them unsuitable as materials for hybrid power sources for use in electric automobiles.
- Japanese Patent Laid-open No. 2003-59491 suggests a method for treating the surface of a cathode active material with conductive carbon black.
- significant improvement has not hitherto been reported.
- Lithium secondary batteries have problems in that the cycle life is drastically shortened due to repeated charge-discharge cycles, especially at high temperatures. The reason for this is that electrolytes are decomposed, active materials are degraded, and the internal resistance of batteries is increased due to the presence of moisture within batteries and other factors. A number of efforts to solve these problems have been made.
- Korean Patent No. 10-277796 discloses a cathode active material surface-coated with a metal oxide, such as an oxide of Mg, Al, Co, K, Na or Ca, by annealing.
- a metal oxide such as an oxide of Mg, Al, Co, K, Na or Ca
- a technique for improving the energy density and high-rate characteristics of lithium secondary batteries by adding TiO to an active material, e.g., LiCoO is suggested (Electrochemical and Solid-State Letters, 4 (6) A65-A67 2001).
- a technique for prolonging the cycle life of lithium secondary batteries by treating the surface of natural graphite with aluminum is known (Electrochemical and Solid-State Letters, 4 (8) A109-A112 2001).
- Korean Patent Laid-open No. 2003-0032363 describes a technique for coating the surface of a cathode active material with a hydroxide, oxyhydroxide, oxycarbonate or hydroxy carbonate of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, or Zr.
- the present invention has been made in view of the above problems, and it is an object of the present invention to provide a cathode active material coated with a fluorine compound powder that is capable of preventing deterioration in the performance of batteries, such as cycle characteristics, particularly at high voltage and high rate by coating of nano-sized fluorine compound.
- a cathode active material for lithium secondary batteries wherein the surface of the cathode active material is coated with a fluorine compound.
- the fluorine compound is at least one compound selected from the group consisting of CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF 2 , BaF 2 , CaF 2 , CuF 2 , CdF 2 , FeF 2 , HgF 2 , Hg ⁇ , MnF 2 , MgF 2 , NiF 2 , PbF 2 , SnF 2 , SrF 2 , XeF 2 , ZnF 2 , AlF 3 , BF 3 , BiF 3 , CeF 3 , CrF 3 , DyF 3 , EuF 3 , GaF 3 , GdF 3 , FeF 3 , HoF 3 , InF 3 , LaF 3 , LuF 3 , MnF 3 , NdF 3 , VOF 3 , PrF 3 , SbF 3 , ScF 3 , SmF 3 , TbF
- the cathode active material coated with the fluorine compound is Li[Co M ]O F or Li [Co M ]O S (0 ⁇ a ⁇ 0.1, 0 ⁇ x ⁇ l-x x 2-a a 1-x x 2-a a
- the cathode active material coated with the fluorine compound is Li [Ni M ]O F or Li [Ni M ]O S (0.01 ⁇ a ⁇ 0.2, 0 l+a l-x x 2-b b 1+a l-x x 2-b b ⁇ b ⁇ 0.1, 0.01 ⁇ x ⁇ 0.5, and M is at least one metal selected from the group consisting of Mg, Al, Co, Mn, Zn, Fe, Cr, Ga, Mo and W) having a hexagonal layered rock-salt structure.
- the cathode active material coated with the fluorine compound is Li [Ni Co Mn ]O F or Li [Ni Co Mn ]O S (0.01 l+a 1-x-y x y 2-b b 1+a 1-x-y x y 2-b b
- the cathode active material coated with the fluorine compound is Li[Li (Ni Co Mn ) ]O F or Li[Li (Ni Co Mn ) ]O S a x l-2x x 1-a 2-b b a x l-2x x 1-a 2 b
- the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x Mn x-y/2 M y) 1-a ]O 2-b F b or Li[Li a (Ni x Co l-2x Mn x-y/2
- M is at least one metal selected from the group consisting of Mg, Ca, Cu and Zn, 0.01 ⁇ a ⁇ 0.2, 0.05 ⁇ x ⁇ 0.5, 0.01 ⁇ y ⁇ 0.1, and 0 ⁇ b ⁇ 0.1) having a hexagonal layered rock-salt structure.
- the cathode active material coated with the fluorine compound is Li[Li a (Ni 1/3 Co (l/3-2x) Mn (1/3+x) M x) 1-a ]O 2-b F b or Li[Li a (Ni 1/3 Co (l/3-2x)
- M is at least one metal selected from the g toroup f consisting to of Mg to,'
- the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x-y Mn x M y) 1-a ]O 2-b F b or Li[Li a (Nix Co l-2x-y Mn x M y )
- M is at least one metal selected from the group consisting of B, Al, Fe and Cr, 0.01 ⁇ a ⁇ 0.2, 0.05 ⁇ x ⁇ 0.5, 0.01 ⁇ y ⁇ 0.1, and 0 ⁇ b ⁇ 0.1) having a hexagonal layered rock-salt structure.
- the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x-y Mn x-z/2 M yN z) 1-a ]O 2-b F b or Li[Li a (Ni x Co l-2x-y Mn x-z/2 M yN z) 1-a ]O 2-b S b (M is at least one metal selected from the g toroup r consisting to of B,> Al,>
- N is Mg or Ca, 0.01 ⁇ a ⁇ 0.2, 0 ⁇ x ⁇ 0.5, 0.01 ⁇ y ⁇ 0.1, and 0 ⁇ b ⁇ 0.1) having a hexagonal layered rock-salt structure.
- the cathode active material coated with the fluorine comp *ound is LiM x Fe l-x PO 4 (M is at least one metal selected from the group consisting of Co, Ni and Mn, and 0 ⁇ x ⁇ 1) having an olivine structure.
- the cathode active material coated with the fluorine compound is spinel Li l+a [Mn 2-x M x ]O 4-b F b or Li l+a [Mn 2-x M x ]O 4-b S b (0.01 ⁇ a
- the cathode active material coated with the fluorine compound is spinel Li [Ni Mn M IO F or Li [Ni Mn M IO S l+a 0.5 1.5-x x 4-b b 1+a 0.5 1.5-x x 4-b b
- M is at least one metal selected from the group consisting of Co, Ni, Cr, Mg, Al, Zn, Mo and W) having a cubic structure.
- a preferred method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries comprising mixing a fluorine (F) compound with an elemental precursor in an aqueous solution to obtain a fluorine compound powder with a high degree of dispersion therein, adding a solution of a cathode active material for lithium secondary batteries to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
- F fluorine
- a method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries comprising mixing a cathode active material for lithium secondary batteries with 0.1-10% by weight of an elemental precursor, relative to the weight of the cathode active material, in an aqueous solution, adding a solution of a fluorine (F) compound to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
- F fluorine
- the methods of the present invention further comprise drying the coated cathode active material at 110°C for 6-24 hours, followed by annealing in an oxidizing or reducing atmosphere or under vacuum at 150-900°C for 1-20 hours.
- the elemental precursor is an alkoxide, sulfate, nitrate, acetate, chloride or phosphate of at least one element selected from the group consisting of Cs, K, Li, Na, Rb, Ti, Ag (I), Ag (II), Ba, Ca, Cu, Cd, Fe, Hg (H), Hg (I), Mn (H), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi (HT), Ce (III), Cr, Dy, Eu, Ga, Gd, Fe, Ho, In, La, Lu, Mn (III), Nd, VO, Pr, Sb (UI), Sc, Sm, Tb, Ti (JlI), Tm, Y, Yb, TL Ce (IV), Ge, Hf, Si, Sn, Ti (IV), V, Zr, Nb, Sb (V), Ta, Bi (V), Mo, Re, S, and W.
- FIG. 1 is a flow chart illustrating the procedure of a method for coating a cathode active material in Example 1 of the present invention
- Fig. 2 shows X-ray diffraction (XRD) patterns of a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention
- Fig. 3 is a field emission scanning electron microscopy (FESEM) image of a cathode active material prepared in Example 1 of the present invention
- Fig. 4 is a field emission scanning electron microscopy (FESEM) image of a cathode active material used in Comparative Example 1 of the present invention
- FIG. 5 and 6 are images showing the results of a cathode active material prepared in Example 1 of the present invention by energy dispersive spectroscopy (EDS);
- Fig. 7 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of
- Fig. 8 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of
- Fig. 9 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of
- Fig. 10 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention according to C-rates in the voltage range of 3.0-4.5 V at room temperature (30°C); [40] Fig.
- FIG. 11 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention according to C-rates in the voltage range of 3.0-4.5 V at a high temperature (55°C);
- Fig. 12 is a graph showing the Co dissolution rate of a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention as a function of time;
- Fig. 13 shows XRD patterns of cathode active materials prepared in Examples 1 to
- FIG. 14 is a graph showing discharge capacity versus number of cycles of half-cells using cathode active materials prepared in Examples 1 to 3 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of 3.0-4.5V at 30°C and a constant current density of 0.2 mA/cm 2 ;
- Fig. 15 shows XRD patterns of cathode active materials prepared in Examples 4 to
- Fig. 16 is a graph showing discharge capacity versus number of cycles of half-cells using cathode active materials prepared in Examples 4 to 6 and a cathode active material used in Comparative Example 2 of the present invention in the voltage range of 3.4-4.3V at 55°C and a constant current density of 1.1 mA/cm (1C); and
- Fig. 17 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 7 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of 3.0-4.5 V at 30°C and a constant current density of 0.8 mA/cm .
- the present invention provides a cathode active material coated with a fluorine compound powder that is capable of preventing deterioration in the performance of lithium secondary batteries, such as cycle characteristics, particularly at high temperature and high rate.
- the fluorine compound coated on the surface of the cathode active material may be at least one compound selected from the group consisting of CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF 2 , BaF 2 , CaF 2 , CuF 2 , CdF 2 , FeF 2 , HgF 2 , Hg ⁇ , MnF 2 , MgF 2 , NiF 2 , PbF 2 , SnF 2 , SrF 2 , XeF 2 , ZnF 2 , AlF 3 , BF 3 , BiF 3 , CeF 3 , CrF 3 , DyF 3 , EuF 3 , GaF 3 , GdF 3 , FeF 3 , HoF 3 , InF 3 , LaF 3 , LuF 3 , MnF 3 , NdF 3 , VOF 3 , PrF 3 , SbF 3 , ScF 3 , SmF 3 , S
- the coating with the fluorine compound reduces the influence of acids formed in the vicinity of the cathode active material and inhibits the reactivity between the cathode active material and an electrolyte so that a drastic reduction in the capacity of batteries can be prevented, thereby improving the charge-discharge characteristics, cycle characteristics, high- voltage and high-rate characteristics, and thermal stability of the final cathode active material for batteries.
- the surface of the cathode active material to be coated with the fluorine compound is amorphous, crystalline, or a mixed state thereof.
- the present invention also provides a preferred method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, the method comprising the steps of mixing a fluorine (F) compound with an elemental precursor in an aqueous solution to obtain a fluorine compound powder with a high degree of dispersion therein, adding a solution of a cathode active material for lithium secondary batteries to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
- F fluorine
- the reason for the high co-precipitation reaction temperature is that the co- precipitation of the elemental precursor enables the formation of a precipitate with a high degree of dispersion in a complex state.
- the fluorine compound powder with a high degree of dispersion is obtained after a certain time of the mixing of the fluorine (F) compound with the elemental precursor. Since the coating is carried out after the formation of the fluorine compound powder with a high degree of dispersion, the necessity of controlling the precipitation rate is avoided when the fluorine (F) compound is added. In addition, since the fluorine compound is previously obtained by mixing the fluorine (F) compound and the elemental precursor, the amount of a solvent used, e.g., an alcohol, which is a more expensive reagent than distilled water, can be reduced, thus reducing the coating cost.
- a solvent used e.g., an alcohol, which is a more expensive reagent than distilled water
- the cathode active material coated with the fluorine compound is prepared in accordance with the following procedure.
- the amount of the fluorine (F)-containing solution used is preferably in the range of
- the coating element there can be used an alkoxide, such as methoxide, ethoxide, isopropoxide or butoxide, sulfate, nitrate, acetate, chloride, or oxide.
- the amount of the coating element used is desirably in the range of 0.1 to 10% by weight, relative to the weight of the cathode active material. If the coating element is used in an amount of less than 0.1% by weight, coating effects are not exhibited. Meanwhile, if the coating element is used in an amount exceeding 10% by weight, the excessive weight of the coating element causes a reduction in the capacity and energy density of batteries.
- the mixed solution containing the cathode active material for lithium secondary batteries and the fluorine compound is reacted at 50-150°C for 3-48 hours.
- the present invention also provides a method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, comprising mixing a cathode active material for lithium secondary batteries with 0.1-10% by weight of an elemental precursor, relative to the weight of the cathode active material, in an aqueous solution, adding a solution of a fluorine (F) compound to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
- a fluorine (F) compound a fluorine (F) compound
- the fluorine compound powder obtained from the mixture of the fluorine (F) compound and the elemental precursor may not have a high degree of dispersion in view of the characteristics of the elemental precursor and has a strong tendency to aggregate so that it has a large size. As a result, an improvement in characteristics may not be expected. Accordingly, it is desirable to control the precipitation rate so that the fluorine compound is slowly formed, and at the same time, it is coated on the surface of the cathode active material.
- the cathode active material coated with the fluorine compound is prepared in accordance with the following procedure.
- at least one elemental precursor selected from Cs, K, Li, Na, Rb, Ti, Ag (I), Ag (II), Ba, Ca, Cu, Cd, Fe, Hg (II), Hg (I), Mn (II), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi (HI), Ce (III), Cr, Dy, Eu, Ga, Gd, Fe, Ho, In, La, Lu, Mn (JlI), Nd, VO, Pr, Sb (III), Sc, Sm, Tb, Ti (HI), Tm, Y, Yb, TI, Ce (IV), Ge, Hf, Si, Sn, Ti (IV), V, Zr, Nb, Sb (V), Ta, Bi (V), Mo, Re, S and W is dissolved in an alcohol, such as a monohydric (e.g., a monohydric (
- the amount of the fluorine (F)-containing solution used is preferably in the range of
- the metal salt there can be used an alkoxide, such as methoxide, ethoxide, isopropoxide or butoxide, sulfate, nitrate, acetate, chloride, or oxide.
- the amount of the coating element used is desirably in the range of 0.1 to 10% by weight, relative to the weight of the cathode active material. If the coating element is used in an amount of less than 0.1% by weight, coating effects are not exhibited. Meanwhile, if the coating element is used in an amount exceeding 10% by weight, the excessive weight of the coating element causes a reduction in the capacity and energy density of batteries.
- the mixed solution containing the cathode active material for lithium secondary batteries and the fluorine compound is reacted at 50-150°C for 3-48 hours.
- the methods of the present invention may further comprise drying the coated cathode active material at 110°C for 6-24 hours, followed by annealing in an oxidizing or reducing atmosphere or under vacuum at 150-900°C for 1-20 hours.
- the annealing serves to remove remaining impurities to obtain the fluorine compound in a desired form and to enhance the binding force of the fluorine compound powder coated on the surface of the cathode active material.
- the reason for the high co- precipitation reaction temperature is that the co-precipitation of AlF enables the formation of a precipitate with a high degree of dispersion in a complex state.
- the LiCoO coated with the fluorine compound was washed with distilled water, dried in a hot-air thermostat at 110°C for 12 hours, and annealed in an inert atmosphere at 400°C, giving the final AlF -coatedLiCoO .
- a 2032 coin cell was fabricated by using the cathode, a lithium foil as a counter electrode, a porous polyethylene film (thickness: 25 D, Celgard 2300, Celgard LLC) as a separator, and a IM LiPF 6 solution in a mixed solvent of ethylene carbonate and dimethyl carbonate (1:1 (Wv)) as a liquid electrolyte in accordance with procedures well known in the art.
- charge-discharge tests were conducted at room temperature (30°C) and a current density of 0.8 mA/cm (Fig. 7), at a high temperature (55°C) and a current density of 0.8 mA/cm (Fig.
- the reason for the high co- precipitation reaction temperature is that the co-precipitation of ZnF enables the formation of a precipitate with a high degree of dispersion in a complex state.
- the LiCoO coated with the fluorine compound was washed with distilled water, dried in a hot-air thermostat at 110°C for 12 hours, and annealed in an inert atmosphere at 400°C, giving the final ZnF -coatedLiCoO .
- a cathode was produced using the ZnF -coated LiCoO , and a coin cell comprising the cathode was fabricated in accordance with the procedure of Example 1.
- a charge-discharge test was conducted at 30°C and a current density of 0.2 mA/cm in the voltage range of 3.0-4.5 V using an electrochemical analysis system (Toscat3000U, Toyo, Japan). Changes in discharge capacity with increasing number of cycles are shown in Fig. 13. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
- the reason for the high co-precipitation reaction temperature is that the co-precipitation of LiF enables the formation of a precipitate with a high degree of dispersion in a complex state.
- the LiCoO coated with the fluorine compound was washed with distilled water, dried in a hot-air thermostat at 110°C for 12 hours, and annealed in an inert atmosphere at 400°C, giving the final LiF-coatedLiCoO .
- a cathode was produced using the LiF-coated LiCoO , and a coin cell comprising the cathode was fabricated.
- a charge- discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 30°C and a current density of 0.2 mA/cm in the voltage range of 3.0-4.5 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 14. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
- AlF 3 -coated LiMn 2 O 4 was p r rep rared, ⁇ > the characteristics of the AlF 3 -coated LiMn 2 O 4 were evaluated, and a cell comprising the AlF -coated LiMn O was fabricated in accordance with the procedure of Example 1.
- a charge-discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 55°C and a current density of 1.1 mA/cm (1C) in the voltage range of 3.4-4.3 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 16. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
- ZnF 2 -coated LiMn 2 O was p V rep *ared,> the characteristics of the ZnF 2 -coated LiMn 2 O were evaluated, and a cell comprising the ZnF -coated LiMn O was fabricated in accordance with the procedure of Example 1.
- a charge-discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 55°C and a current density of 1.1 mA/cm (1C) in the voltage range of 3.4-4.3 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 16. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
- LiF-coated LiMn O was prepared, the characteristics of the LiF-coated LiMn O were evaluated, and a cell comprising the LiF-coated LiMn O was fabricated in accordance with the procedure of Example 1.
- a charge-discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 55°C and a current density of 1.1 mA/cm 2 (1C) in the voltage range of 3.4-4.3 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 16. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
- Fig. 2 shows XRD patterns of the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1.
- Fig. 4 is a FESEM image of the cathode active material used in Comparative Example 1.
- Fig. 7 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 in the voltage range of 3.0-4.5 V at room temperature (30°C) and a constant current density of
- Fig. 8 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 in the voltage range of 3.0-4.5 V at a high temperature (55°C) and a constant current density of 0.8 mA/cm .
- Fig. 9 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Compara tive Example 1 in the voltage range of 3.0-4.5 V at room temperature (30°C) and a constant current density of 0.2 mA/cm 2 .
- Fig. 8 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 in the voltage range of 3.0-4.5 V at a high temperature (55°C) and a constant current density of 0.8 mA/cm
- Fig. 10 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 according to C-rates in the voltage range of 3.0-4.5V at room temperature (30°C).
- Fig. 11 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 according to C-rates in the voltage range of 3.0-4.5 V at a high temperature (55°C).
- Fig. 12 is a graph showing the Co dissolution rate of the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 as a function of time.
- Fig. 12 is a graph showing the Co dissolution rate of the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 as a function of time.
- FIG. 13 shows XRD patterns of the cathode active materials prepared in Examples 1 to 3 and the cathode active material used in Comparative Example 1.
- FIG. 14 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active materials prepared in Examples 1 to 3 and the cathode active material used in Comparative Example 1 in the voltage range of 3.0-4.5 V at 30°C and a constant current density of 0.2 mA/cm .
- [124] [ 125] Comparative Example 2
- Fig. 15 shows XRD patterns of the cathode active materials prepared in Examples 4 to 6 and the cathode active material used in Comparative Example 2.
- Fig. 16 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active materials prepared in Examples 4 to 6 and the cathode active material used in Comparative Example 2 in the voltage range of 3.4-4.3 V at 55°C and a constant current density of Ll mA/cm 2 (lC).
- the coating of a cathode active material for lithium secondary batteries with a fluorine compound reduces the influence of acids formed in the vicinity of the cathode active material and inhibits the reactivity between the cathode active material and an electrolyte so that a drastic reduction in the capacity of batteries can be prevented, thereby improving the charge-discharge characteristics, cycle characteristics, high- voltage and high-rate characteristics, and thermal stability of the final cathode active material for batteries.
Abstract
Disclosed herein is a cathode active material coated with a fluorine compound for lithium secondary batteries. The cathode active material is structurally stable, and improves the charge-discharge characteristics, cycle characteristics, high-voltage characteristics, high-rate characteristics and thermal stability of batteries.
Description
Description
CATHODE ACTIVE MATERIAL COATED WITH FLUORINE
COMPOUND FOR LITHIUM SECONDARY BATTERIES AND
METHOD FOR PREPARING THE SAME
Technical Field
[1] The present invention relates to a method for treating the surface of a cathode active material for lithium secondary batteries with superior cycle characteristics and excellent high-rate characteristics. More particularly, the present invention relates to an improvement in the charge-discharge characteristics, cycle characteristics, high-voltage characteristics and thermal stability of lithium secondary batteries by coating a cathode active material for the lithium secondary batteries with a fluorine compound.
[2]
Background Art
[3] Demand for rechargeable lithium secondary batteries as power sources of portable electronic devices for digital communication, such as personal digital assistants (PDAs), cellular phones and notebooks, as well as electric bicycles and electric automobiles is rapidly growing. The performance of these devices is greatly influenced by secondary batteries as key components of the devices. Accordingly, there is a strong need for high-performance batteries. Several main characteristics required in batteries are charge-discharge characteristics, cycle characteristics, high-rate characteristics, and high-temperature stability. Lithium secondary batteries have drawn attention because of their high voltage and high energy density.
[4] Lithium secondary batteries are classified into lithium metal batteries using lithium as an anode and lithium ion batteries using an interlayer compound, e.g., carbon, capable of intercalation/deintercalation of lithium ions. Further, lithium secondary batteries are classified into liquid type batteries using a liquid electrolyte, gel type polymer batteries using a mixture of liquid and polymer electrolytes, and solid type polymer batteries using a pure polymer electrolyte according to the kind of electrolytes used.
[5] Currently available small-size lithium ion secondary batteries use LiCoO as a cathode material and carbon as an anode material. Lithium ion secondary batteries using LiMn O as a cathode material were developed by MoIi Energy Corp., Japan, but their use is negligible in comparison with that of batteries using LiCoO . Extensive research on LiNiO 2 , LiCo x Ni 1-x O 2 and LiMn 2 O 4 is actively J underway J as cathode materials. LiCoO 2 is a promising material in terms of its stable charge-discharge char- acteristics, high electronic conductivity, superior thermal stability and constant
discharge voltage characteristics, but has disadvantages of insufficient cobalt deposits, high price and toxicity. For these reasons, development of novel cathode materials is needed. LiNiO has problems that it is difficult to synthesize and is thermally unstable, which make LiNiO unsuitable for commercialization. Commercial applications of LiMn 2 O 4 are currently limited to some low-priced products. However, LiMn 2 O 4 is has a spinel structure and deliverers a lower theoretical capacity (-148 mAh/g) than other active materials. In addition, LiMn 2 O 4 has poor cycle characteristics due to the Mn dissolution into electrolyte. Particularly, since LiMn O has poor high-temperature characteristics at 55°C or higher when compared to LiCoO , it has not yet been put to practical use in batteries.
[6] To overcome these problems, numerous studies have focused on materials having a layered crystal structure. Under such circumstances, Li[Ni Mn ]O (nickel: manganese = 1:1) and Li[Ni Co Mn ]O (nickel: cobalt: manganese = 1:1:1), each
1/3 1/3 1/3 2 of which has a layered crystal structure, are currently in the spotlight. These materials are advantageous over LiCoO in terms their low price, high capacity and superior thermal stability. [7] However, since Li[Ni 1/2 Mn 1/2 ]O 2 and Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 have a lower electronic conductivity than LiCoO , they show poor high-rate characteristics and poor low- temp rerature characteristics. Further, since Li[Ni 1/2 Mn 1/2 ]O 2 and Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 have a low tap density, no improvement in the energy density of batteries is achieved despite their high capacity. Particularly, the electronic conductivity of Li[Ni Mn ]O is extremely low, which causes difficulty in the commercialization of the material (J. of Power Sources, ' 112 ( V2002) ' 41-48) '. Particularly •", Li[ LNi 1/2 Mn 1/2 ]JO 2 and Li[ LNi 1/3 Co 1/3
Mn 1/3 ]O 2 show poor high-power characteristics over LiCoO 2 and LiMn 2 O 4 , which makes them unsuitable as materials for hybrid power sources for use in electric automobiles. In an attempt to solve such problems, Japanese Patent Laid-open No. 2003-59491 suggests a method for treating the surface of a cathode active material with conductive carbon black. However, significant improvement has not hitherto been reported. [8] Lithium secondary batteries have problems in that the cycle life is drastically shortened due to repeated charge-discharge cycles, especially at high temperatures. The reason for this is that electrolytes are decomposed, active materials are degraded, and the internal resistance of batteries is increased due to the presence of moisture within batteries and other factors. A number of efforts to solve these problems have been made. For example, Korean Patent No. 10-277796 discloses a cathode active material surface-coated with a metal oxide, such as an oxide of Mg, Al, Co, K, Na or Ca, by annealing. A technique for improving the energy density and high-rate characteristics of lithium secondary batteries by adding TiO to an active material, e.g.,
LiCoO , is suggested (Electrochemical and Solid-State Letters, 4 (6) A65-A67 2001). A technique for prolonging the cycle life of lithium secondary batteries by treating the surface of natural graphite with aluminum is known (Electrochemical and Solid-State Letters, 4 (8) A109-A112 2001). However, the problems of the shortened cycle life and gas evolution arising from the decomposition of electrolytes during charge and discharge still remain unsolved. Further, active materials may be dissolved by acids formed from the oxidation of electrolytes during charge due to a reduction in the capacity of batteries (Journal of Electrochemical Society, 143 (1996) P2204). In recent years, Korean Patent Laid-open No. 2003-0032363 describes a technique for coating the surface of a cathode active material with a hydroxide, oxyhydroxide, oxycarbonate or hydroxy carbonate of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, or Zr.
[9]
Disclosure of Invention Technical Problem
[10] The present invention has been made in view of the above problems, and it is an object of the present invention to provide a cathode active material coated with a fluorine compound powder that is capable of preventing deterioration in the performance of batteries, such as cycle characteristics, particularly at high voltage and high rate by coating of nano-sized fluorine compound.
[H]
Technical Solution
[12] In accordance with one aspect of the present invention for achieving the above object, there is provided a cathode active material for lithium secondary batteries wherein the surface of the cathode active material is coated with a fluorine compound.
[13] In one preferred embodiment of the present invention, the fluorine compound is at least one compound selected from the group consisting of CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF2, BaF2, CaF2, CuF2, CdF2, FeF2, HgF2, Hg^, MnF2, MgF2, NiF2, PbF2, SnF2, SrF2, XeF2, ZnF2, AlF3, BF3, BiF3, CeF3, CrF3, DyF3, EuF3, GaF3, GdF3, FeF3, HoF3, InF3, LaF3, LuF3, MnF3, NdF3, VOF3, PrF3, SbF3, ScF3, SmF3, TbF3, TiF3, TmF3,
YF , YbF , TIF , CeF , GeF , HfF , SiF , SnF , TiF , VF , ZrF , NbF , SbF , TaF , BiF ,
3 3 3 4 4 4 4 4 4 4 4 5 5 5 5
MoF , ReF , SF , WF , and other fluorine-containing compounds.
6 6 6 6
[14] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li[Co M ]O F or Li [Co M ]O S (0 < a < 0.1, 0 < x < l-x x 2-a a 1-x x 2-a a
0.1, and M is at least one metal selected from the group consisting of Mg, Al, Ni, Mn, Zn, Fe, Cr, Ga, Mo and W) having a hexagonal layered rock-salt structure. [15] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li [Ni M ]O F or Li [Ni M ]O S (0.01 < a < 0.2, 0 l+a l-x x 2-b b 1+a l-x x 2-b b
< b < 0.1, 0.01 < x < 0.5, and M is at least one metal selected from the group consisting of Mg, Al, Co, Mn, Zn, Fe, Cr, Ga, Mo and W) having a hexagonal layered rock-salt structure.
[16] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li [Ni Co Mn ]O F or Li [Ni Co Mn ]O S (0.01 l+a 1-x-y x y 2-b b 1+a 1-x-y x y 2-b b
< a < 0.2, 0 < b < 0.1, 0.05 < x < 0.4, 0.05 < y < 0.35, and 0.1 < x + y < 0.75) having a hexagonal layered rock-salt structure.
[17] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li[Li (Ni Co Mn ) ]O F or Li[Li (Ni Co Mn ) ]O S a x l-2x x 1-a 2-b b a x l-2x x 1-a 2 b
(0.01 < a < 0.2, 0.05 < x < 0.5, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[18] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x Mn x-y/2 M y) 1-a ]O 2-b F b or Li[Li a (Ni x Co l-2x Mn x-y/2
M y) 1-a ]O 2-b S b (M is at least one metal selected from the group consisting of Mg, Ca, Cu and Zn, 0.01 < a < 0.2, 0.05 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[19] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li[Li a (Ni 1/3 Co (l/3-2x) Mn (1/3+x) M x) 1-a ]O 2-b F b or Li[Li a (Ni 1/3 Co (l/3-2x)
Mn (1/3+x) M x)'l-a ]O 2-b S b (M is at least one metal selected from the g toroup f consisting to of Mg to,'
Ca, Cu and Zn, 0.01 < a < 0.2, 0 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[20] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x-y Mn x M y) 1-a ]O 2-b F b or Li[Li a (Nix Co l-2x-y Mn x M y )
]O S (M is at least one metal selected from the group consisting of B, Al, Fe and Cr, 0.01 < a < 0.2, 0.05 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[21] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x-y Mn x-z/2 M yN z) 1-a ]O 2-b F b or Li[Li a (Ni x Co l-2x-y Mn x-z/2 M yN z) 1-a ]O 2-b S b (M is at least one metal selected from the g toroup r consisting to of B,> Al,>
Fe and Cr, N is Mg or Ca, 0.01 < a < 0.2, 0 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[22] In one embodiment of the present invention, the cathode active material coated with the fluorine comp *ound is LiM x Fe l-x PO 4 (M is at least one metal selected from the group consisting of Co, Ni and Mn, and 0 < x < 1) having an olivine structure. [23] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is spinel Li l+a [Mn 2-x M x ]O 4-b F b or Li l+a [Mn 2-x M x ]O 4-b S b (0.01 < a
< 0.15, 0 < b < 0.1, 0 < x < 0.1, and M is at least one metal selected from the group consisting of Co, Ni, Cr, Mg, Al, Zn, Mo and W) having a cubic structure.
[24] In one embodiment of the present invention, the cathode active material coated with the fluorine compound is spinel Li [Ni Mn M IO F or Li [Ni Mn M IO S l+a 0.5 1.5-x x 4-b b 1+a 0.5 1.5-x x 4-b b
(0.01 < a < 0.15, 0 < b < 0.1, 0 < x < 0.1, and M is at least one metal selected from the group consisting of Co, Ni, Cr, Mg, Al, Zn, Mo and W) having a cubic structure.
[25] In accordance with another aspect of the present invention, there is provided a preferred method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, the method comprising mixing a fluorine (F) compound with an elemental precursor in an aqueous solution to obtain a fluorine compound powder with a high degree of dispersion therein, adding a solution of a cathode active material for lithium secondary batteries to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
[26] In accordance with yet another aspect of the present invention, there is provided a method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, the method comprising mixing a cathode active material for lithium secondary batteries with 0.1-10% by weight of an elemental precursor, relative to the weight of the cathode active material, in an aqueous solution, adding a solution of a fluorine (F) compound to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
[27] In one preferred embodiment, the methods of the present invention further comprise drying the coated cathode active material at 110°C for 6-24 hours, followed by annealing in an oxidizing or reducing atmosphere or under vacuum at 150-900°C for 1-20 hours.
[28] In one preferred embodiment of the present invention, the elemental precursor is an alkoxide, sulfate, nitrate, acetate, chloride or phosphate of at least one element selected from the group consisting of Cs, K, Li, Na, Rb, Ti, Ag (I), Ag (II), Ba, Ca, Cu, Cd, Fe, Hg (H), Hg (I), Mn (H), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi (HT), Ce (III), Cr, Dy, Eu, Ga, Gd, Fe, Ho, In, La, Lu, Mn (III), Nd, VO, Pr, Sb (UI), Sc, Sm, Tb, Ti (JlI), Tm, Y, Yb, TL Ce (IV), Ge, Hf, Si, Sn, Ti (IV), V, Zr, Nb, Sb (V), Ta, Bi (V), Mo, Re, S, and W.
[29]
Brief Description of the Drawings
[30] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
[31] Fig. 1 is a flow chart illustrating the procedure of a method for coating a cathode
active material in Example 1 of the present invention; [32] Fig. 2 shows X-ray diffraction (XRD) patterns of a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention; [33] Fig. 3 is a field emission scanning electron microscopy (FESEM) image of a cathode active material prepared in Example 1 of the present invention; [34] Fig. 4 is a field emission scanning electron microscopy (FESEM) image of a cathode active material used in Comparative Example 1 of the present invention; [35] Figs. 5 and 6 are images showing the results of a cathode active material prepared in Example 1 of the present invention by energy dispersive spectroscopy (EDS); [36] Fig. 7 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of
3.0-4.5V at room temperature (30°C) and a constant current density of 0.8 mA/cm ; [37] Fig. 8 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of
3.0-4.5V at a high temperature (55°C) and a constant current density of 0.8 mA/cm ; [38] Fig. 9 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of
3.0-4.5 V at room temperature (30°C) and a constant current density of 0.2 mA/cm ; [39] Fig. 10 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention according to C-rates in the voltage range of 3.0-4.5 V at room temperature (30°C); [40] Fig. 11 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention according to C-rates in the voltage range of 3.0-4.5 V at a high temperature (55°C); [41] Fig. 12 is a graph showing the Co dissolution rate of a cathode active material prepared in Example 1 and a cathode active material used in Comparative Example 1 of the present invention as a function of time; [42] Fig. 13 shows XRD patterns of cathode active materials prepared in Examples 1 to
3 and a cathode active material used in Comparative Example 1 of the present invention; [43] Fig. 14 is a graph showing discharge capacity versus number of cycles of half-cells using cathode active materials prepared in Examples 1 to 3 and a cathode active
material used in Comparative Example 1 of the present invention in the voltage range of 3.0-4.5V at 30°C and a constant current density of 0.2 mA/cm2;
[44] Fig. 15 shows XRD patterns of cathode active materials prepared in Examples 4 to
6 and a cathode active material used in Comparative Example 2 of the present invention;
[45] Fig. 16 is a graph showing discharge capacity versus number of cycles of half-cells using cathode active materials prepared in Examples 4 to 6 and a cathode active material used in Comparative Example 2 of the present invention in the voltage range of 3.4-4.3V at 55°C and a constant current density of 1.1 mA/cm (1C); and
[46] Fig. 17 is a graph showing discharge capacity versus number of cycles of half-cells using a cathode active material prepared in Example 7 and a cathode active material used in Comparative Example 1 of the present invention in the voltage range of 3.0-4.5 V at 30°C and a constant current density of 0.8 mA/cm .
[47]
Best Mode for Carrying Out the Invention
[48] Hereinafter, the present invention will be described in greater detail.
[49] The present invention provides a cathode active material coated with a fluorine compound powder that is capable of preventing deterioration in the performance of lithium secondary batteries, such as cycle characteristics, particularly at high temperature and high rate.
[50] The fluorine compound coated on the surface of the cathode active material may be at least one compound selected from the group consisting of CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF2, BaF2, CaF2, CuF2, CdF2, FeF2, HgF2, Hg^, MnF2, MgF2, NiF2, PbF2, SnF2, SrF2, XeF2, ZnF2, AlF3, BF3, BiF3, CeF3, CrF3, DyF3, EuF3, GaF3, GdF3, FeF3, HoF3, InF3, LaF3, LuF3, MnF3, NdF3, VOF3, PrF3, SbF3, ScF3, SmF3, TbF3, TiF3, TmF3,
YF , YbF , TIF , CeF , GeF , HfF , SiF , SnF , TiF , VF , ZrF , NbF , SbF , TaF , BiF ,
3 3 3 4 4 4 4 4 4 4 4 5 5 5 5
MoF , ReF , SF , WF , and other fluorine-containing compounds.
6 6 6 6
[51] The coating with the fluorine compound reduces the influence of acids formed in the vicinity of the cathode active material and inhibits the reactivity between the cathode active material and an electrolyte so that a drastic reduction in the capacity of batteries can be prevented, thereby improving the charge-discharge characteristics, cycle characteristics, high- voltage and high-rate characteristics, and thermal stability of the final cathode active material for batteries.
[52] The surface of the cathode active material to be coated with the fluorine compound is amorphous, crystalline, or a mixed state thereof.
[53] The present invention also provides a preferred method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, the
method comprising the steps of mixing a fluorine (F) compound with an elemental precursor in an aqueous solution to obtain a fluorine compound powder with a high degree of dispersion therein, adding a solution of a cathode active material for lithium secondary batteries to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
[54] The reason for the high co-precipitation reaction temperature is that the co- precipitation of the elemental precursor enables the formation of a precipitate with a high degree of dispersion in a complex state.
[55] The fluorine compound powder with a high degree of dispersion is obtained after a certain time of the mixing of the fluorine (F) compound with the elemental precursor. Since the coating is carried out after the formation of the fluorine compound powder with a high degree of dispersion, the necessity of controlling the precipitation rate is avoided when the fluorine (F) compound is added. In addition, since the fluorine compound is previously obtained by mixing the fluorine (F) compound and the elemental precursor, the amount of a solvent used, e.g., an alcohol, which is a more expensive reagent than distilled water, can be reduced, thus reducing the coating cost.
[56] Specifically, the cathode active material coated with the fluorine compound is prepared in accordance with the following procedure. First, at least one elemental precursor selected from Cs, K, Li, Na, Rb, Ti, Ag (I), Ag (II), Ba, Ca, Cu, Cd, Fe, Hg (II), Hg (I), Mn (II), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi (HI), Ce (III), Cr, Dy, Eu, Ga, Gd, Fe, Ho, In, La, Lu, Mn (HI), Nd, VO, Pr, Sb (III), Sc, Sm, Tb, Ti (UL), Tm, Y, Yb, TI, Ce (IV), Ge, Hf, Si, Sn, Ti (IV), V, Zr, Nb, Sb (V), Ta, Bi (V), Mo, Re, S and W is dissolved in an alcohol, such as a monohydric (e.g., methanol, ethanol or isopropanol) or dihydric alcohol (e.g., ethylene glycol or butyl glycol), or distilled water. A fluorine (F)-containing solution is added to the solution to obtain a metal fluoride compound powder. Thereafter, a cathode active material for lithium secondary batteries is added to the mixed solution so that it is coated with the metal fluoride compound.
[57] The amount of the fluorine (F)-containing solution used is preferably in the range of
1 to 20 moles, relative to one mole of the coating element. As the elemental precursor, there can be used an alkoxide, such as methoxide, ethoxide, isopropoxide or butoxide, sulfate, nitrate, acetate, chloride, or oxide. The amount of the coating element used is desirably in the range of 0.1 to 10% by weight, relative to the weight of the cathode active material. If the coating element is used in an amount of less than 0.1% by weight, coating effects are not exhibited. Meanwhile, if the coating element is used in an amount exceeding 10% by weight, the excessive weight of the coating element causes a reduction in the capacity and energy density of batteries. The mixed solution
containing the cathode active material for lithium secondary batteries and the fluorine compound is reacted at 50-150°C for 3-48 hours.
[58] In another aspect, the present invention also provides a method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, comprising mixing a cathode active material for lithium secondary batteries with 0.1-10% by weight of an elemental precursor, relative to the weight of the cathode active material, in an aqueous solution, adding a solution of a fluorine (F) compound to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
[59] According to the previous method, the fluorine compound powder obtained from the mixture of the fluorine (F) compound and the elemental precursor may not have a high degree of dispersion in view of the characteristics of the elemental precursor and has a strong tendency to aggregate so that it has a large size. As a result, an improvement in characteristics may not be expected. Accordingly, it is desirable to control the precipitation rate so that the fluorine compound is slowly formed, and at the same time, it is coated on the surface of the cathode active material.
[60] Specifically, the cathode active material coated with the fluorine compound is prepared in accordance with the following procedure. First, at least one elemental precursor selected from Cs, K, Li, Na, Rb, Ti, Ag (I), Ag (II), Ba, Ca, Cu, Cd, Fe, Hg (II), Hg (I), Mn (II), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi (HI), Ce (III), Cr, Dy, Eu, Ga, Gd, Fe, Ho, In, La, Lu, Mn (JlI), Nd, VO, Pr, Sb (III), Sc, Sm, Tb, Ti (HI), Tm, Y, Yb, TI, Ce (IV), Ge, Hf, Si, Sn, Ti (IV), V, Zr, Nb, Sb (V), Ta, Bi (V), Mo, Re, S and W is dissolved in an alcohol, such as a monohydric (e.g., methanol, ethanol or isopropanol) or dihydric alcohol (e.g., ethylene glycol or butyl glycol), or distilled water. A cathode active material for lithium secondary batteries is added to the solution. Thereafter, to the mixed solution is added a fluorine (F)-containing solution so that the cathode active material for lithium secondary batteries is coated with the metal fluoride compound.
[61] The amount of the fluorine (F)-containing solution used is preferably in the range of
1 to 20 moles, relative to one mole of the coating element. As the metal salt, there can be used an alkoxide, such as methoxide, ethoxide, isopropoxide or butoxide, sulfate, nitrate, acetate, chloride, or oxide. The amount of the coating element used is desirably in the range of 0.1 to 10% by weight, relative to the weight of the cathode active material. If the coating element is used in an amount of less than 0.1% by weight, coating effects are not exhibited. Meanwhile, if the coating element is used in an amount exceeding 10% by weight, the excessive weight of the coating element causes a reduction in the capacity and energy density of batteries. The mixed solution containing the cathode active material for lithium secondary batteries and the fluorine
compound is reacted at 50-150°C for 3-48 hours.
[62] The methods of the present invention may further comprise drying the coated cathode active material at 110°C for 6-24 hours, followed by annealing in an oxidizing or reducing atmosphere or under vacuum at 150-900°C for 1-20 hours. The annealing serves to remove remaining impurities to obtain the fluorine compound in a desired form and to enhance the binding force of the fluorine compound powder coated on the surface of the cathode active material.
[63]
Mode for the Invention
[64] The present invention will now be described in more detail with reference to the following examples. However, these examples are not to be construed as limiting the scope of the invention.
[65]
[66] Example 1
[67] 1. Preparation of AlF -coated LiCoO
[68] 2 mol% of Al(NO ) -9H O was dissolved in 150 ml of distilled water in a 500-ml beaker, and then a commercially available LiCoO active material was contained therein. The mixture was stirred. Separately, 150 ml of a solution of NH 4 F (6 mol%) was continuously added to the previous solution at a flow rate of 1 ml/min while maintaining the temperature of the reactor at 80°C. The mixed solution was subjected to co-precipitation, followed by stirring for 24 hours. At this time, the average temperature of the reactor was maintained at 80°C. The reason for the high co- precipitation reaction temperature is that the co-precipitation of AlF enables the formation of a precipitate with a high degree of dispersion in a complex state. The LiCoO coated with the fluorine compound was washed with distilled water, dried in a hot-air thermostat at 110°C for 12 hours, and annealed in an inert atmosphere at 400°C, giving the final AlF -coatedLiCoO .
[69]
[[7700]] 2. Evaluation of characteristics of AlF 3 -coatedLiCoO 2
[71] i) XRD
[72] A Ann XX--rraay diffraction pattern of the AlF -coatedLiCoO was obtained using an X-ray diffraction analyzer (Rint-2000, Rigaku, Japan). The pattern is shown in Fig. 2. [73]
[74] ii) Scanning Electron Microscopy (SEM)
[75] An image of the AlF -coatedLiCoO prepared in Example 1 was obtained using a
SEM (JSM 6400, JEOL, Japan), and the image is shown in Fig. 3. [76]
[77] iii) Energy Dispersive Spectroscopy (EDS)
[78] An image of the AlF -coatedLiCoO prepared in Example 1 was obtained using an
EDS (JSM 6400, JEOL, Japan), and the image is shown in Fig. 5. The image indicates uniform distribution of Al and F. [79]
[80] 3. Production of cathode
[81] 20 mg of the AlF -coated LiCoO , 8 mg of teflonized acetylene black and 4 mg of graphite were homogeneously mixed. The mixture was uniformly pressed under a load of 1 ton using a stainless steel Ex-met, and dried at 100°C to produce a cathode for lithium secondary batteries. [82]
[83] 4. Fabrication of coin cell
[84] A 2032 coin cell was fabricated by using the cathode, a lithium foil as a counter electrode, a porous polyethylene film (thickness: 25 D, Celgard 2300, Celgard LLC) as a separator, and a IM LiPF 6 solution in a mixed solvent of ethylene carbonate and dimethyl carbonate (1:1 (Wv)) as a liquid electrolyte in accordance with procedures well known in the art. [85] To evaluate the characteristics of the coin cell, charge-discharge tests were conducted at room temperature (30°C) and a current density of 0.8 mA/cm (Fig. 7), at a high temperature (55°C) and a current density of 0.8 mA/cm (Fig. 8), and at room temperature (30°C) and a constant current density of 0.2 mA/cm2 (Fig. 9) in the voltage range of 3.0-4.5 V using an electrochemical analysis system (Toscat3000U, Toyo, Japan). Changes in discharge capacity with increasing number of cycles are shown in Figs. 7 to 9. After 50 cycles of discharging and recharging, the AlF -coated LiCoO showed a capacity retention of 93% at 0.8 mA/cm2 at room temperature (30°C), a capacity retention of 99% at 0.2 mA/cm at room temperature (30°C), and a capacity retention of 90% at 0.8 mA/cm2 at a high temperature of 55°C. These results demonstrate that there is little or no decrease in capacity retention with increasing number of cycles.
[86] To evaluate the high-rate characteristics of the cell, charge-discharge tests were conducted at room temperature (30°C) (Fig. 10) and at a high temperature (55°C) (Fig. 11) in the voltage range of 3.0-4.5 V under various current density conditions using an electrochemical analysis system (Toscat3000U, Toyo, Japan). Changes in discharge capacity with increasing number of cycles are shown in Figs. 10 and 11. The graphs demonstrate that the AlF -coated LiCoO shows superior high-rate characteristics both at room temperature (30°C) and a high temperature (55°C) under various current density conditions, compared to LiCoO .
[87] To evaluate the Co dissolution of the AlF -coated LiCoO , after three cycles of
charging and recharging in the potential range of 3.0-4.5 V at a high temperature (60°C), the coin cell was charged to 4.5V at the 4-th cycle. Thereafter, the cell was disassembled to separate the cathode. The cathode was immersed in an electrolyte and stored in a thermostat at 60°C. Changes in the Co concentration in the electrolyte were analyzed with the passage of time using an atomic absorption spectroscopy (AAS) (Varionό, Analytik-jena, Germany). The analytical results of the Co dissolution are shown in Fig. 8. For the AAS analysis, a Co standard solution (1,000 ppm, AnApex Co. Ltd. Korea) was diluted to 100 ppm and 10 ppm sequentially to optimize the concentrations (ppm). Using the optimized concentrations, a calibration curve was plotted. As a result, the calibration curve had a confidence level of 99.99%. Co was dissolved at 86.925 ppm from LiCoO within the electrolyte after 336 hours, whereas Co was dissolved at 23.275 ppm from the AlF -coated LiCoO within the electrolyte after 336 hours. From these results, it is apparent that the coating with AlF considerably decreases the Co dissolution.
[88]
[89] Example 2
[90] Preparation of ZnF -coated LiCoO
[91] 2 mol% of Zn(NO ) -H O was dissolved in 150 ml of distilled water in a 500-ml beaker, and then a commercially available LiCoO active material was contained therein. The mixture was stirred. Separately, 150 ml of a solution of NH 4 F (4 mol%) was continuously added to the previous solution at a flow rate of 1 ml/min while maintaining the temperature of the reactor at 80°C. The mixed solution was subjected to co-precipitation, followed by stirring for 24 hours. At this time, the average temperature of the reactor was maintained at about 80°C. The reason for the high co- precipitation reaction temperature is that the co-precipitation of ZnF enables the formation of a precipitate with a high degree of dispersion in a complex state. The LiCoO coated with the fluorine compound was washed with distilled water, dried in a hot-air thermostat at 110°C for 12 hours, and annealed in an inert atmosphere at 400°C, giving the final ZnF -coatedLiCoO .
[92]
[93] 2. XRD evaluation of ZnF 2 -coated LiCoO 2
[94] An X-ray diffraction pattern of the ZnF -coated LiCoO was obtained using an X- ray diffraction analyzer. The pattern is shown in Fig. 13. [95]
[96] 3. Fabrication of coin cell and evaluation of characteristics
[97] A cathode was produced using the ZnF -coated LiCoO , and a coin cell comprising the cathode was fabricated in accordance with the procedure of Example 1. [98] To evaluate the characteristics of the coin cell, a charge-discharge test was
conducted at 30°C and a current density of 0.2 mA/cm in the voltage range of 3.0-4.5 V using an electrochemical analysis system (Toscat3000U, Toyo, Japan). Changes in discharge capacity with increasing number of cycles are shown in Fig. 13. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
[99]
[100] Example 3
[101] Preparation of LiF-coated LiCoO
[102] 2 mol% of LiNO was dissolved in 150 ml of distilled water in a 500-ml beaker, and then a commercially available LiCoO active material was contained therein. The mixture was stirred. Separately, 150 ml of a solution of NH 4 F (2 mol%) was con- tinuously added to the previous solution at a flow rate of 1 ml/min while maintaining the temperature of the reactor at 80°C. The mixed solution was subjected to co- precipitation, followed by stirring for 24 hours. At this time, the average temperature of the reactor was maintained at about 80°C. The reason for the high co-precipitation reaction temperature is that the co-precipitation of LiF enables the formation of a precipitate with a high degree of dispersion in a complex state. The LiCoO coated with the fluorine compound was washed with distilled water, dried in a hot-air thermostat at 110°C for 12 hours, and annealed in an inert atmosphere at 400°C, giving the final LiF-coatedLiCoO .
[103]
[ 104] 2. XRD evaluation of LiF-coated LiCoO
2
[105] An X-ray diffraction pattern of the LiF-coated LiCoO was obtained using an X-ray diffraction analyzer. The pattern is shown in Fig. 13.
[106]
[107] 3. Fabrication of coin cell and evaluation of characteristics
[108] A cathode was produced using the LiF-coated LiCoO , and a coin cell comprising the cathode was fabricated. To evaluate the characteristics of the coin cell, a charge- discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 30°C and a current density of 0.2 mA/cm in the voltage range of 3.0-4.5 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 14. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
[109]
[110] Example 4
[111] AlF 3 -coated LiMn 2 O 4 was p rrep rared, ■> the characteristics of the AlF 3 -coated LiMn 2 O4 were evaluated, and a cell comprising the AlF -coated LiMn O was fabricated in
accordance with the procedure of Example 1. To evaluate the characteristics of the coin cell, a charge-discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 55°C and a current density of 1.1 mA/cm (1C) in the voltage range of 3.4-4.3 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 16. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
[112]
[113] Example 5
[114] ZnF 2 -coated LiMn 2 O was p Vrep *ared,> the characteristics of the ZnF 2 -coated LiMn 2 O were evaluated, and a cell comprising the ZnF -coated LiMn O was fabricated in accordance with the procedure of Example 1. To evaluate the characteristics of the coin cell, a charge-discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 55°C and a current density of 1.1 mA/cm (1C) in the voltage range of 3.4-4.3 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 16. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
[115]
[116] Example 6
[117] LiF-coated LiMn O was prepared, the characteristics of the LiF-coated LiMn O were evaluated, and a cell comprising the LiF-coated LiMn O was fabricated in accordance with the procedure of Example 1. To evaluate the characteristics of the coin cell, a charge-discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at 55°C and a current density of 1.1 mA/cm2 (1C) in the voltage range of 3.4-4.3 V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 16. The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics.
[118]
[119] Example 7
[120] 2 kg of AlF -coated LiCoO was prepared in a 70-L reactor in the same manner as in Example 1. The characteristics of the AlF -coated LiCoO were evaluated, and a cell comprising the AlF -coated LiCoO was fabricated in accordance with the procedure of Example 1. To evaluate the characteristics of the coin cell, a charge-discharge test was conducted using an electrochemical analysis system (Toscat3000U, Toyo, Japan) at
30°C and a current density of 0.8 mA/cm (lC)in the voltage range of 3.0-4.5V. Changes in discharge capacity with increasing number of cycles are shown in Fig. 17.
The graph shows that there is a slight decrease in the discharge capacity of the coin cell with increasing number of cycles, indicating superior cycle characteristics. The cell comprising the AlF -coated LiCoO prepared in a larger amount (2 kg) in Example 7 exhibited the same effects as that comprising the AlF -coated LiCoO prepared in a smaller amount in Example 1.
[121]
[122] Comparative Example 1
[123] The characteristics of a commercially available uncoated LiCoO cathode active material were evaluated by the procedure of Example 1. Fig. 2 shows XRD patterns of the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1. Fig. 4 is a FESEM image of the cathode active material used in Comparative Example 1. Fig. 7 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 in the voltage range of 3.0-4.5 V at room temperature (30°C) and a constant current density of
0.8 mA/cm . Fig. 8 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 in the voltage range of 3.0-4.5 V at a high temperature (55°C) and a constant current density of 0.8 mA/cm . Fig. 9 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Compara tive Example 1 in the voltage range of 3.0-4.5 V at room temperature (30°C) and a constant current density of 0.2 mA/cm2. Fig. 10 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 according to C-rates in the voltage range of 3.0-4.5V at room temperature (30°C). Fig. 11 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 according to C-rates in the voltage range of 3.0-4.5 V at a high temperature (55°C). Fig. 12 is a graph showing the Co dissolution rate of the cathode active material prepared in Example 1 and the cathode active material used in Comparative Example 1 as a function of time. Fig. 13 shows XRD patterns of the cathode active materials prepared in Examples 1 to 3 and the cathode active material used in Comparative Example 1. Fig. 14 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active materials prepared in Examples 1 to 3 and the cathode active material used in Comparative Example 1 in the voltage range of 3.0-4.5 V at 30°C and a constant current density of 0.2 mA/cm . [124]
[ 125] Comparative Example 2
[126] The characteristics of a commercially available uncoated LiMn O cathode active material were evaluated by the procedure of Example 1. Fig. 15 shows XRD patterns of the cathode active materials prepared in Examples 4 to 6 and the cathode active material used in Comparative Example 2. Fig. 16 is a graph showing discharge capacity versus number of cycles of the half-cells using the cathode active materials prepared in Examples 4 to 6 and the cathode active material used in Comparative Example 2 in the voltage range of 3.4-4.3 V at 55°C and a constant current density of Ll mA/cm2(lC).
[127]
Industrial Applicability
[128] The coating of a cathode active material for lithium secondary batteries with a fluorine compound reduces the influence of acids formed in the vicinity of the cathode active material and inhibits the reactivity between the cathode active material and an electrolyte so that a drastic reduction in the capacity of batteries can be prevented, thereby improving the charge-discharge characteristics, cycle characteristics, high- voltage and high-rate characteristics, and thermal stability of the final cathode active material for batteries.
Claims
[1] A cathode active material for lithium secondary batteries wherein the surface of the cathode active material is coated with a fluorine compound.
[2] The cathode active material according to claim 1, wherein the fluorine compound is at least one compound selected from the group consisting of CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF2, BaF2, CaF2, CuF2, CdF2, FeF2, HgF2, Hg^, MnF2, MgF 2 , NiF 2 , PbF 2 , SnF 2 , SrF 2 , XeF 2 , ZnF 2 , AlF 3 , BF3 , BiF 3 , CeF 3 , CrF 3 , DyF3 ,
EuF3, GaF3, GdF3, FeF3, HoF3, InF3, LaF3, LuF3, MnF3, NdF3, VOF3, PrF3, SbF3, ScF3, SmF3, TbF3, TiF3, TmF3, YF3, YbF3, TIF3, CeF4, GeF4, HfF4, SiF4, SnF4, TiF , VF , ZrF , NbF , SbF , TaF , BiF , MoF , ReF , SF , WF , and other
4 4 4 5 5 5 5 6 6 6 6 fluorine-containing compounds. [3] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li[Co M ]O F or Li[Co M ]O l-x x 2-a a 1-x x
S (0 < a < 0.1, 0.01 < x < 0.1, and M is at least one metal selected from the
2-a a group consisting of Mg, Al, Ni, Mn, Zn, Fe, Cr, Ga, Mo and W) having a hexagonal layered rock-salt structure. [4] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li [Ni M ]O F or Li [Ni M l+a l-x x 2-b b 1+a l-x
]O S (0.01 < a < 0.2, 0 < b < 0.1, 0.01 < x < 0.5, and M is at least one metal x 2-b b selected from the group consisting of Mg, Al, Co, Mn, Zn, Fe, Cr, Ga, Mo and W) having a hexagonal layered rock-salt structure.
[5] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li l+a [Ni 1-x-y Co x Mn y ]O 2-b F b or Li l+a
[Ni l-x-y Co xMn y]O 2-b S b (0.01 < a < 0.2, 0 < b < 0.1, 0.05 < x < 0.4, 0.05 < y J <
0.35, and 0.1 < x + y < 0.75) having a hexagonal layered rock-salt structure.
[6] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li[Li (Ni Co Mn ) ]O F or Li[Li a (Ni x Co l-2x Mn x ) 1-a ]O 2 S b (0.01 < a < 0.2, 0.05 < x < 0.5, and 0* < b < 0.1) having a hexagonal layered rock-salt structure.
[7] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x Mn x-y/2 M y ) 1-a ]O 2-b F b or Li[Li (Ni Co Mn M ) ]O S (M is at least one metal selected from the a x l-2x x-y/2 y 1-a 2-b b group consisting of Mg, Ca, Cu and Zn, 0.01 < a < 0.2, 0.05 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[8] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li[Li a (Ni 1/3 Co (l/3-2x) Mn (1/3+x) M x ) 1-a ]
O F or Li[Li (Ni Co Mn M ) ]O S (M is at least one metal selected
2-b b a 1/3 (l/3-2x) (1/3+x) x 1-a 2-b b
from the group consisting of Mg, Ca, Cu and Zn, 0.01 < a < 0.2, 0 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[9] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li[Li (Ni Co Mn M ) ]O F a x l-2x-y x y 1-a 2-b b or Li[Li (Ni Co Mn M ) ]O S (M is at least one metal selected from the a x l-2x-y x y 1-a 2-b b group consisting of B, Al, Fe and Cr, 0.01 < a < 0.2, 0.05 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[10] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is Li[Li a (Ni x Co l-2x-y Mn x-z/2 M yN z) 1-a ]O
F or Li[Li (Ni Co Mn M N ) ]O S (M is at least one metal selected
2-b b a x l-2x-y x-z/2 y z 1-a 2-b b from the group consisting of B, Al, Fe and Cr, N is Mg or Ca, 0.01 < a < 0.2, 0 < x < 0.5, 0.01 < y < 0.1, and 0 < b < 0.1) having a hexagonal layered rock-salt structure.
[11] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine comp Vound is LiM x Fe l-x PO 4 ( VM is at least one metal selected from the group consisting of Co, Ni and Mn, and 0 < x < 1) having an olivine structure.
[12] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is spinel Li l+a [Mn 2-x M x ]O 4-b F b or Li 1+a
[Mn 2-x M x]O 4-b S b (0.01 < a < 0.15, 0 < b < 0.1, 0 < x < 0.1, and M is at least one metal selected from the group consisting of Co, Ni, Cr, Mg, Al, Zn, Mo and W) having a cubic structure.
[13] The cathode active material according to claim 1, wherein the cathode active material coated with the fluorine compound is spinel Li [Ni Mn M ]O F l+a 0.5 1.5-x x 4-b b or Li [Ni Mn M ]O S (0.01 < a < 0.15, 0 < b < 0.1, 0 < x < 0.1, and M is l+a 0.5 1.5-x x 4-b b at least one metal selected from the group consisting of Co, Ni, Cr, Mg, Al, Zn, Mo and W) having a cubic structure.
[14] A method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, the method comprising mixing a fluorine (F) compound with an elemental precursor in an aqueous solution to obtain a fluorine compound powder with a high degree of dispersion therein, adding a solution of a cathode active material for lithium secondary batteries to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
[15] A method for preparing a cathode active material coated with a fluorine compound for lithium secondary batteries, the method comprising the steps of mixing a cathode active material for lithium secondary batteries with 0.1-10% by weight of an elemental precursor, relative to the weight of the cathode active
material, in an aqueous solution, adding a solution of a fluorine (F) compound to the aqueous solution, and reacting the mixed solution at 50-100°C for 3-48 hours to coat the cathode active material with the fluorine compound.
[16] The method according to claim 14 or 15, further comprising drying the coated cathode active material at 110°C for 6-24 hours, followed by annealing in an oxidizing or reducing atmosphere or under vacuum at 150-900°C for 1-20 hours.
[17] The method according to any one of claims 14 to 16, wherein the elemental precursor is an alkoxide, sulfate, nitrate, acetate, chloride or phosphate of at least one element selected from the group consisting of Cs, K, Li, Na, Rb, Ti, Ag (I), Ag (H), Ba, Ca, Cu, Cd, Fe, Hg (II), Hg (I), Mn (TI), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi (UL), Ce (III), Cr, Dy, Eu, Ga, Gd, Fe, Ho, In, La, Lu, Mn (III), Nd, VO, Pr, Sb (IE), Sc, Sm, Tb, Ti (III), Tm, Y, Yb, TL Ce (TV), Ge, Hf, Si, Sn, Ti (IV), V, Zr, Nb, Sb (V), Ta, Bi (V), Mo, Re, S, and W.
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| EP06716437A EP1880435A4 (en) | 2005-04-15 | 2006-03-17 | Cathode active material coated with fluorine compound for lithium secondary batteries and method for preparing the same |
| US11/918,163 US9048495B2 (en) | 2005-04-15 | 2006-03-17 | Cathode active material coated with flourine compound for lithium secondary batteries and method for preparing the same |
| JP2008506363A JP2008536285A (en) | 2005-04-15 | 2006-03-17 | Positive electrode active material for lithium secondary battery coated with fluorine compound and method for producing the same |
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| KR1020060023501A KR100822013B1 (en) | 2005-04-15 | 2006-03-14 | Cathode active material coated with fluorine compounds for lithium secondary batteries and method of producing thereof |
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| US20100086853A1 (en) * | 2008-10-07 | 2010-04-08 | Subramanian Venkatachalam | Positive electrode materials for lithium ion batteries having a high specific discharge capacity and processes for the synthesis of these materials |
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| JP2011519126A (en) * | 2008-04-16 | 2011-06-30 | エンビア・システムズ・インコーポレイテッド | High energy lithium ion secondary battery |
| EP2374175A2 (en) * | 2008-12-11 | 2011-10-12 | Envia Systems, Inc. | Positive electrode materials for high discharge capacity lithium ion batteries |
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| EP1880435A1 (en) | 2008-01-23 |
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