US20190393497A1 - Lithiated silicon/carbon composite materials and method for producing the same - Google Patents
Lithiated silicon/carbon composite materials and method for producing the same Download PDFInfo
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- US20190393497A1 US20190393497A1 US16/561,204 US201916561204A US2019393497A1 US 20190393497 A1 US20190393497 A1 US 20190393497A1 US 201916561204 A US201916561204 A US 201916561204A US 2019393497 A1 US2019393497 A1 US 2019393497A1
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- United States
- Prior art keywords
- lithium
- composite materials
- lithiated
- carbonate
- silicon
- Prior art date
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- 239000002131 composite material Substances 0.000 title claims abstract description 54
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 47
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 13
- 239000010703 silicon Substances 0.000 title claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 7
- 229910052799 carbon Inorganic materials 0.000 title description 4
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 69
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 68
- 238000000034 method Methods 0.000 claims abstract description 27
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 26
- 239000010439 graphite Substances 0.000 claims abstract description 26
- 239000000843 powder Substances 0.000 claims abstract description 25
- 239000002245 particle Substances 0.000 claims abstract description 21
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910021389 graphene Inorganic materials 0.000 claims abstract description 17
- 239000000463 material Substances 0.000 claims abstract description 11
- 239000011863 silicon-based powder Substances 0.000 claims abstract description 9
- 238000010521 absorption reaction Methods 0.000 claims abstract description 4
- 239000011248 coating agent Substances 0.000 claims description 23
- 239000010405 anode material Substances 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 10
- 239000011247 coating layer Substances 0.000 claims description 8
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 8
- 239000000470 constituent Substances 0.000 claims description 7
- 125000000524 functional group Chemical group 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 claims description 6
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 5
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 5
- 239000003960 organic solvent Substances 0.000 claims description 5
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 5
- 239000011856 silicon-based particle Substances 0.000 claims description 5
- BJWMSGRKJIOCNR-UHFFFAOYSA-N 4-ethenyl-1,3-dioxolan-2-one Chemical compound C=CC1COC(=O)O1 BJWMSGRKJIOCNR-UHFFFAOYSA-N 0.000 claims description 4
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 4
- 150000004651 carbonic acid esters Chemical group 0.000 claims description 4
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 4
- 239000011255 nonaqueous electrolyte Substances 0.000 claims description 4
- 229910019256 POF3 Inorganic materials 0.000 claims description 3
- 150000002484 inorganic compounds Chemical class 0.000 claims description 3
- 229910010272 inorganic material Inorganic materials 0.000 claims description 3
- FFUQCRZBKUBHQT-UHFFFAOYSA-N phosphoryl fluoride Chemical compound FP(F)(F)=O FFUQCRZBKUBHQT-UHFFFAOYSA-N 0.000 claims description 2
- 239000000203 mixture Substances 0.000 description 20
- 229910001416 lithium ion Inorganic materials 0.000 description 12
- 238000000227 grinding Methods 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 10
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 9
- 150000001875 compounds Chemical class 0.000 description 9
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 8
- 230000002687 intercalation Effects 0.000 description 7
- 238000009830 intercalation Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 229910021332 silicide Inorganic materials 0.000 description 7
- 229910013458 LiC6 Inorganic materials 0.000 description 6
- 239000002904 solvent Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- -1 e.g. Chemical class 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 3
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- 229910010661 Li22Si5 Inorganic materials 0.000 description 3
- 229910013733 LiCo Inorganic materials 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 3
- 229910052808 lithium carbonate Inorganic materials 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 2
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 229910000733 Li alloy Inorganic materials 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
- KAESVJOAVNADME-UHFFFAOYSA-N Pyrrole Chemical compound C=1C=CNC=1 KAESVJOAVNADME-UHFFFAOYSA-N 0.000 description 2
- 229910000676 Si alloy Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 150000001335 aliphatic alkanes Chemical class 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 239000011244 liquid electrolyte Substances 0.000 description 2
- 238000006138 lithiation reaction Methods 0.000 description 2
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 2
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical class [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 2
- 229910001947 lithium oxide Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- WDXYVJKNSMILOQ-UHFFFAOYSA-N 1,3,2-dioxathiolane 2-oxide Chemical compound O=S1OCCO1 WDXYVJKNSMILOQ-UHFFFAOYSA-N 0.000 description 1
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 description 1
- BSKHPKMHTQYZBB-UHFFFAOYSA-N 2-methylpyridine Chemical class CC1=CC=CC=N1 BSKHPKMHTQYZBB-UHFFFAOYSA-N 0.000 description 1
- KGIGUEBEKRSTEW-UHFFFAOYSA-N 2-vinylpyridine Chemical compound C=CC1=CC=CC=N1 KGIGUEBEKRSTEW-UHFFFAOYSA-N 0.000 description 1
- URBKPKQEPDPNSQ-UHFFFAOYSA-N 4-ethenyl-1,3,2-dioxathiolane 2-oxide Chemical compound C=CC1COS(=O)O1 URBKPKQEPDPNSQ-UHFFFAOYSA-N 0.000 description 1
- 229910015900 BF3 Inorganic materials 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 241000871495 Heeria argentea Species 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910011184 Li7Si3 Inorganic materials 0.000 description 1
- 229910013465 LiC12 Inorganic materials 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 1
- 229920005987 OPPANOL® Polymers 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229920002367 Polyisobutene Polymers 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000000783 alginic acid Substances 0.000 description 1
- 235000010443 alginic acid Nutrition 0.000 description 1
- 229920000615 alginic acid Polymers 0.000 description 1
- 229960001126 alginic acid Drugs 0.000 description 1
- 150000004781 alginic acids Chemical class 0.000 description 1
- 125000005376 alkyl siloxane group Chemical group 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 150000001733 carboxylic acid esters Chemical class 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- TXLQIRALKZAWHN-UHFFFAOYSA-N dilithium carbanide Chemical compound [Li+].[Li+].[CH3-].[CH3-] TXLQIRALKZAWHN-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 229940021013 electrolyte solution Drugs 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229940093499 ethyl acetate Drugs 0.000 description 1
- 235000019439 ethyl acetate Nutrition 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- ZTOMUSMDRMJOTH-UHFFFAOYSA-N glutaronitrile Chemical compound N#CCCCC#N ZTOMUSMDRMJOTH-UHFFFAOYSA-N 0.000 description 1
- 125000000623 heterocyclic group Chemical group 0.000 description 1
- 238000010952 in-situ formation Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical class [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 150000003457 sulfones Chemical class 0.000 description 1
- 150000008053 sultones Chemical class 0.000 description 1
- 238000001149 thermolysis Methods 0.000 description 1
- ZTWTYVWXUKTLCP-UHFFFAOYSA-N vinylphosphonic acid Chemical compound OP(O)(=O)C=C ZTWTYVWXUKTLCP-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/381—Alkaline or alkaline earth metals elements
- H01M4/382—Lithium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the invention relates to composite materials comprising Li, Si and C, wherein the electrochemical rest potential of these compounds is below approximately 2 V, preferably below 1 V, measured against Li/Li + .
- Silicon is one of the most-promising anode materials for lithium batteries of the next generation.
- the semimetal has an extremely high absorbing capacity for lithium via the mechanism of alloy formation: for example, the alloy Li 22 Si 5 has a maximum theoretical capacity of 4200 Ah/kg, which is more than ten times higher than that of the graphites currently built into lithium ion batteries (372 Ah/kg).
- the high volume changes (>300%) during charging/discharging result in a pulverizing and a separation of the connection from the current arrester so that a poor reversibility and an extremely rapid capacity drop take place.
- a reversible capacity of up to 740 mAh/g corresponding to a composition LiC 3 is considered to be possible, according to the document US 2015/0000118 A1.
- the electrochemical properties of silicon can be improved by reducing the particle sizes in the submicron range, by alloy formation with other elements, nanostructuring of electrodes or by admixing components which buffer the volume change (e.g., carbon).
- An improved anode material mainly based on silicon is sought.
- This material should be able to be produced by a commercially advantageous process.
- composite materials of this invention comprising lithiated or partially-lithiated graphite or graphene and silicon having particle sizes from about 1 ⁇ m to about 100 ⁇ m, and having an electrochemical rest potential less than about 2 V measured against Li/Li + .
- Such composite materials can also comprise metallic lithium.
- such composite materials can have a coating layer comprising functional groups or molecular constituents that have reacted with lithium that was available on the composite materials' surfaces, including wherein the coating layer is applied with one or more gaseous or liquid coating means.
- Also provided are methods for producing composite materials comprising combining (i) a graphitic material with particle sizes from about 5 ⁇ m to about 200 ⁇ m and a silicon powder with particle sizes from about 1 ⁇ m to about 100 ⁇ m in a molar ratio of 9:1 to 1:9 with (ii) a lithium powder with a particle sizes from about 5 ⁇ m to about 500 ⁇ m under inert gas conditions to form a combination and mechanochemically converting the combination in a temperature range of about 0° C. to about 120° C.
- the amount of lithium in the composite materials is in the range of about 10 molar % to about 100 molar % of the stochiometrically maximally possible lithium absorption.
- the mechanochemically converting is conducted in a temperature range of about 20° C. to about 100° C., and/or such methods comprising also combining metallic lithium particles having sizes between about 5 ⁇ m to about 500 ⁇ m to form the combination.
- such methods comprising subjecting the produced composite materials to a temperature of about 150° C. to about 350° C. for about 5 minutes to about 24 hours.
- Such methods additionally comprising applying to the produced composite materials a coating layer comprising functional groups or molecular constituents such that the functional groups or molecular constituents react with lithium available on the composite materials' surfaces, including applying the coating layer via a gaseous coating agent or a liquid coating agent, and wherein the gaseous coating agent is selected from N 2 , CO 2 , CO, O 2 , N 2 O, NO, NO 2 , HF, F 2 , PF 3 , PF 5 , and POF 3 , and the liquid coating agent is selected from carbonic acid esters, vinyl ethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate; lithium chelateoborate solutions in organic solvents, and inorganic compounds.
- the gaseous coating agent is selected from N 2 , CO 2 , CO, O 2 , N 2 O, NO, NO 2 , HF, F 2 , PF 3 , PF
- composite materials that comprise lithiated or partially-lithiated graphite or graphene and silicon particles having sizes from about 1 ⁇ m to about 100 ⁇ m, and that have an electrochemical rest potential less than about 2 V measured against Li/Li + , as anode material in galvanic cells with non-aqueous electrolytes and/or as anode materials in lithium batteries.
- the composite materials that comprise lithiated or partially-lithiated graphite or graphene, and silicon particles having sizes between 1 to 100 ⁇ m, and that have an electrochemical rest potential less than about 2 V measured against Li/Li+, can be used as anode material in galvanic cells with non-aqueous electrolytes.
- the composite materials that comprise lithiated or partially-lithiated graphite or graphene, and silicon particles having sizes between 1 to 100 ⁇ m, and that have an electrochemical rest potential less than about 2 V measured against Li/Li+, can be used as anode material in lithium batteries.
- the amount of the lithium in the composite materials of this invention is in the range of about 10 to 100 molar % of the stochiometrically maximally possible lithium absorption (LiC 6 and Li 22 Si 5 are the thermodynamically Li-richest stable phases at room temperature).
- the production of the composite materials of the invention takes place for example via a grinding process which can be optionally combined with a tempering process.
- the graphitic material for example graphite powder with particle sizes between 5 and 200 ⁇ m or graphene powder
- silicon powder particle size 1 to 100 ⁇ m
- lithium powder particle size 5 to 500 ⁇ m
- the mechanically induced conversion takes place in the temperature range between 0 and 120° C., preferably 20 to 100° C. either in vacuum or under an atmosphere whose components do not react or only acceptably slowly react with metallic lithium, silicon and/or lithium graphite intercalation compounds.
- This is preferably either dry air or a noble gas, especially preferably argon.
- the lithium is added in powdery form comprising particles with an average particle size between about 5 and 500 ⁇ m preferably 10 and 200 ⁇ m.
- Coated powders such as, e.g., a stabilized metallic powder offered by the FMC company (Lectromax powder 100, SLMP) with a lithium content of at least 97 wt % or, for example, a powder coated with alloy-forming elements and with metallic contents of at least 95 wt % (WO2013/104787A1) are used.
- Non-coated lithium powders with a metallic content of ⁇ 99 wt % are especially preferably used.
- the sodium content must not be >200 ppm.
- the Na content is preferably ⁇ 100 ppm, especially preferably ⁇ 80 ppm.
- All powdery graphite qualities can be used as graphite.
- Macrocrystalline flake graphites as well as amorphous or microcrystalline graphites can be used.
- the oxygen content should be below 5 wt %, preferably below 1 wt %.
- the silicon powder has a content of at least 80 wt % Si, preferably at least 90 wt % Si; and the remainder substantially comprises oxygen.
- the conversion (that is the lithiation or partial lithiation) of the graphite or graphene takes place during admixing, compression and/or grinding of the two components lithium powder and graphite-or graphene powder in the presence of the Si powder.
- the grinding can take place by mortar and pestle on a laboratory scale.
- the conversion preferably takes place in a mechanical mill, for example, a rod mill, oscillating mill or ball mill.
- the conversion is especially advantageously carried out in a planet ball mill.
- the planet ball mill Pulverisette 7 premium line from the Fritsch company can be used on a laboratory scale.
- the mixture of lithium powder and graphite powder is preferably ground in the dry state.
- a fluid which is inert to both substances can also be added up to a weight ratio of up to 1:1 (sum of Li+C+Si:fluid).
- the inert fluid is preferably a non-aqueous hydrocarbon solvent, e.g., a liquid alkane or alkane mixture or an aromatic hydrocarbon mixture. The vigorousness of the grinding process is dampened and the graphite particles are groundless strongly by the addition of solvents.
- the grinding time is a function of various requirements and process parameters:
- the grinding times fluctuate between 5 minutes and 24 hours, preferably between 10 minutes and 10 hours.
- a composite is present consisting of lithiated or partially lithiated graphite/graphene powder, largely unchanged Si-Powder and lithium metallic remainders.
- lithiated or partially lithiated composite powders are “active” to environmental conditions (air and water) and to many functionalized solvents (e.g., NMP) and liquid electrolyte solutions, i.e. they react or decompose upon rather long exposure times.
- functionalized solvents e.g., NMP
- liquid electrolyte solutions i.e. they react or decompose upon rather long exposure times.
- the contained lithium reacts under the development of hydrogen to thermodynamically stable salts such as lithium hydroxide, lithium oxide and/or lithium carbonate.
- the lithiated or partially lithiated composite powders can be stabilized by a second process step, a coating method. To this end the lithiated or partially lithiated composite powder is passivated with a gaseous or liquid coating agent.
- the coating agents used contain, compared to metallic lithium and lithium graphite intercalation compounds or lithium graphene intercalation compounds, reactive functional groups or molecular constituents and they therefore react with the lithium available on the surface.
- the conversion of the lithium-containing surface zone takes place under the formation of lithium salts such as, e.g., lithium carbonate, lithium chloride, lithium hydroxide, lithium alcoholates, lithium carboxylates, etc.) which are non-reactive or only slightly reactive to air (therefore thermodynamically stable).
- lithium salts such as, e.g., lithium carbonate, lithium chloride, lithium hydroxide, lithium alcoholates, lithium carboxylates, etc.
- Such coating means are known from lithium ion battery technology as in-situ film producers (also designated as a SEI producers) for the negative electrodes and are described, for example, in the following survey article: A. Lex-Balducci, W. Henderson, S. Passerini, Electrolytes for Lithium Ion Batteries, in Lithium - Ion Batteries, Advanced Materials and Technologies , X. Yuan, H. Liu and J. Zhang (Hrsg.), CRC Press Boca Raton, 2012, p. 147-196. Coating agents used are cited by way of example in the following.
- Suitable gases are N 2 , CO 2 , CO, O 2 , N 2 O, NO, NO 2 , HF, F 2 , PF 3 , PF 5 , POF 3 and the like.
- Liquid coating agents used are, for example: carbonic acid esters (e.g., vinylene carbonate (VC), vinyl ethylene carbonate (VEC) ,ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), fluoroethylene carbonate (FEC)); lithium chelateoborate solutions (e.g., lithium bis(oxalato)borate (LiBOB), lithium bis(salicylato)borate (LiBSB), lithium bis(malonato)borate (LiBMB), lithium difluorooxalatoborate (LiDFOB) as solutions in organic solvents, preferably selected from: oxygen-containing heterocycles such as T
- the coating process When using liquid coating agents the coating process generally takes place under an atmosphere of inert gas (e.g., argon protective atmosphere) at temperatures between 0 and 150° C.
- inert gas e.g., argon protective atmosphere
- mixing or agitating conditions are advantageous.
- the necessary contact time between the coating agent and the lithiated or partially lithiated composite powder is a function of the reactivity of the coating agent, of the prevailing temperature and of other process parameters. In general, times between 1 minute and 24 hours are appropriate.
- the coating not only improves the handling properties and the safety in the production of electrodes (generally anodes) but also the properties of use in an electrochemical battery cell.
- electrodes generally anodes
- anode materials When pre-coated anode materials are used, the in situ formation of an SEI (solid electrolyte interface) is eliminated upon contact of the lithiated or partially lithiated composite anode material with the liquid electrolyte of the battery cell.
- SEI solid electrolyte interface
- the anode filming brought about outside of the electrochemical cell by pre-coating corresponds in its properties to a so-called artificial SEI. In the ideal case the otherwise necessary forming process of the electrochemical cell is eliminated or it is at least simplified.
- the composite products lithiated or partially lithiated and stabilized according to the above-described method can be used to produce battery electrodes. For this, they are mixed and homogenized under inert or dry spatial conditions with at least one binder material and optionally with a conductivity-improving additive (e.g., blacks or metallic powder, e.g., Ni powder or Ni foam) and with an organic solvent and this dispersion is applied by a coating method (casting method, spin coating or airbrush method) onto a current arrester and dried.
- a coating method (casting method, spin coating or airbrush method) onto a current arrester and dried.
- the stabilized lithiated or partially lithiated composite powders produced according to the method of the invention are surprisingly not very reactive to N-methylpyrrolidone (NMP) and to other functionalized, organic solvents.
- NMP N-methylpyrrolidone
- binder materials polyvinylidene fluoride (PVdF) to a castable or sprayable dispersion.
- suitable binder materials are, among others: carboxymethyl cellulose (CMC), polyisobutylene (e.g., OPPANOL of the BASF Company), alginic acid.
- the described, non-coated, lithiated or partially lithiated composites are subjected following the mechanochemical conversion to a temperature step at temperatures between 100 and 350° C., preferably between 150 and 250° C.
- a tempering time of 5 minutes to 24 h a conversion takes place between the lithiated or partially lithiated graphite-/graphene compounds and optionally any elementary (metallic) lithium still present to alloys of lithium and silicon (lithium silicides, e.g. Li 7 Si 3 ).
- lithium silicides e.g. Li 7 Si 3
- Upon maintaining sufficient storage times at a certain temperature it is possible to extract all lithium intercalated in the graphite or graphene and to use it for the production of the lithium silicides. In this manner a silicide composite is produced in the extreme case which consists of lithium-free or very lithium-poor graphite/graphene and lithium silicides.
- the exact composition results from the stoichiometry of
- non-coated, lithiated or partially lithiated composites as well as the silicide composites in contact with electrolytic solutions and carbonate solvents are more stable than pure lithium-graphite intercalation compounds.
- the materials according to the invention have an improved thermal stability compared to an EC/EMC mixture.
- the composite materials are not self-igniting in air as a rule. This is the opposite of the behavior of non-coated LiC 6 .
- the electrochemical rest potential of the composite material of the invention is below about 2 V, preferably below 1 V measured against Li/Li + .
- the composite materials according to the invention can be used as high-capacitive anode materials for galvanic cells with non-aqueous electrolytes, for example lithium batteries.
- the product surprisingly proved to be non-self-igniting in air. It vigorously reacts with N-methylpyrrolidone after a short time.
- the product is not self-igniting in air. It reacts mildly with NMP at room temperature.
- the product is not self-igniting in air. It reacts only extremely weakly with NMP at room temperature.
- the examples show the production of Li/C/Si composites with a high lithium content (52 wt % of maximum lithium capacity) and their qualitative composition.
- a thermal post-treatment improves the stability to reactive solvents shown, for example, on a mixture with N-methyl pyrrolidone.
Abstract
Description
- This application is a continuation-in-part of U.S. application Ser. No. 15/546,746 dated Jul. 27, 2017, which is the National Stage of International Patent Application Number PCT/EP2016/051680, filed on Jan. 27, 2016, which in turn claims benefit of German Application Number 10 2015 201 461.4, filed on Jan. 28, 2015, the disclosures of which are incoroporated herein by reference.
- The invention relates to composite materials comprising Li, Si and C, wherein the electrochemical rest potential of these compounds is below approximately 2 V, preferably below 1 V, measured against Li/Li+.
- Silicon is one of the most-promising anode materials for lithium batteries of the next generation. The semimetal has an extremely high absorbing capacity for lithium via the mechanism of alloy formation: for example, the alloy Li22Si5 has a maximum theoretical capacity of 4200 Ah/kg, which is more than ten times higher than that of the graphites currently built into lithium ion batteries (372 Ah/kg). Unfortunately, the high volume changes (>300%) during charging/discharging result in a pulverizing and a separation of the connection from the current arrester so that a poor reversibility and an extremely rapid capacity drop take place. For graphene, a reversible capacity of up to 740 mAh/g corresponding to a composition LiC3 is considered to be possible, according to the document US 2015/0000118 A1.
- The electrochemical properties of silicon can be improved by reducing the particle sizes in the submicron range, by alloy formation with other elements, nanostructuring of electrodes or by admixing components which buffer the volume change (e.g., carbon).
- When using silicon as anode material in lithium batteries there is another problem in that very high, irreversible losses are recorded during the first charge/discharge cycle. They can be traced back primarily to the content of foreign elements such as, e.g., oxygen, hydrogen and inorganic carbon (e.g., carbonate). The foreign elements react irreversibly with lithium to electrochemically inactive products such as lithium oxides, lithium carbonate, lithium carbide, lithium hydroxide, etc.
- An improved anode material mainly based on silicon is sought.
- This material should be able to be produced by a commercially advantageous process.
- The problem is solved with composite materials of this invention comprising lithiated or partially-lithiated graphite or graphene and silicon having particle sizes from about 1 μm to about 100 μm, and having an electrochemical rest potential less than about 2 V measured against Li/Li+. Such composite materials can also comprise metallic lithium. Further, such composite materials can have a coating layer comprising functional groups or molecular constituents that have reacted with lithium that was available on the composite materials' surfaces, including wherein the coating layer is applied with one or more gaseous or liquid coating means.
- Also provided are methods for producing composite materials comprising combining (i) a graphitic material with particle sizes from about 5 μm to about 200 μm and a silicon powder with particle sizes from about 1 μm to about 100 μm in a molar ratio of 9:1 to 1:9 with (ii) a lithium powder with a particle sizes from about 5 μm to about 500 μm under inert gas conditions to form a combination and mechanochemically converting the combination in a temperature range of about 0° C. to about 120° C. under inert gas or in a vacuum, into the composite materials, wherein the amount of lithium in the composite materials is in the range of about 10 molar % to about 100 molar % of the stochiometrically maximally possible lithium absorption. Included are such methods wherein the mechanochemically converting is conducted in a temperature range of about 20° C. to about 100° C., and/or such methods comprising also combining metallic lithium particles having sizes between about 5 μm to about 500 μm to form the combination. Also provided are such methods comprising subjecting the produced composite materials to a temperature of about 150° C. to about 350° C. for about 5 minutes to about 24 hours. Also provided are such methods additionally comprising applying to the produced composite materials a coating layer comprising functional groups or molecular constituents such that the functional groups or molecular constituents react with lithium available on the composite materials' surfaces, including applying the coating layer via a gaseous coating agent or a liquid coating agent, and wherein the gaseous coating agent is selected from N2, CO2, CO, O2, N2O, NO, NO2, HF, F2, PF3, PF5, and POF3, and the liquid coating agent is selected from carbonic acid esters, vinyl ethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate; lithium chelateoborate solutions in organic solvents, and inorganic compounds.
- Also covered by the present invention is the use of composite materials that comprise lithiated or partially-lithiated graphite or graphene and silicon particles having sizes from about 1 μm to about 100 μm, and that have an electrochemical rest potential less than about 2 V measured against Li/Li+, as anode material in galvanic cells with non-aqueous electrolytes and/or as anode materials in lithium batteries.
- The composite materials that comprise lithiated or partially-lithiated graphite or graphene, and silicon particles having sizes between 1 to 100 μm, and that have an electrochemical rest potential less than about 2 V measured against Li/Li+, can be used as anode material in galvanic cells with non-aqueous electrolytes.
- Preferably, the composite materials that comprise lithiated or partially-lithiated graphite or graphene, and silicon particles having sizes between 1 to 100 μm, and that have an electrochemical rest potential less than about 2 V measured against Li/Li+, can be used as anode material in lithium batteries.
- The amount of the lithium in the composite materials of this invention is in the range of about 10 to 100 molar % of the stochiometrically maximally possible lithium absorption (LiC6 and Li22Si5 are the thermodynamically Li-richest stable phases at room temperature). The production of the composite materials of the invention takes place for example via a grinding process which can be optionally combined with a tempering process. To this end, the graphitic material (for example graphite powder with particle sizes between 5 and 200 μm or graphene powder) is mixed with silicon powder (particle size 1 to 100 μm) in a molar ratio of 9:1 to 1:9 and with lithium powder (particle size 5 to 500 μm) under inert gas conditions (e.g., Ar) and is subsequently compressed or ground. At this time Li-graphite intercalates with the composition LiCo (o=e.g., 6 or 12), meaning that lithium atoms are intercalated in graphite in a molar ratio of 1:6 or 1:12, surprisingly form at first, whereas no or only an entirely subordinate reaction or alloy formation takes place between silicon and lithium metal.
- The mechanically induced conversion takes place in the temperature range between 0 and 120° C., preferably 20 to 100° C. either in vacuum or under an atmosphere whose components do not react or only acceptably slowly react with metallic lithium, silicon and/or lithium graphite intercalation compounds. This is preferably either dry air or a noble gas, especially preferably argon.
- The lithium is added in powdery form comprising particles with an average particle size between about 5 and 500 μm preferably 10 and 200 μm. Coated powders such as, e.g., a stabilized metallic powder offered by the FMC company (Lectromax powder 100, SLMP) with a lithium content of at least 97 wt % or, for example, a powder coated with alloy-forming elements and with metallic contents of at least 95 wt % (WO2013/104787A1) are used. Non-coated lithium powders with a metallic content of ≥99 wt % are especially preferably used. For a use in the battery area the purity regarding metallic contaminations must be very high. Among other things, the sodium content must not be >200 ppm. The Na content is preferably ≤100 ppm, especially preferably ≤80 ppm.
- All powdery graphite qualities, both those from naturally occurring ones (so-called “natural graphite”) as well as synthetically/industrially produced types (“synthetic graphites”) can be used as graphite. Macrocrystalline flake graphites as well as amorphous or microcrystalline graphites can be used. As regards graphenes, there is basically no limitation. However, the oxygen content should be below 5 wt %, preferably below 1 wt %. The silicon powder has a content of at least 80 wt % Si, preferably at least 90 wt % Si; and the remainder substantially comprises oxygen.
- The conversion (that is the lithiation or partial lithiation) of the graphite or graphene takes place during admixing, compression and/or grinding of the two components lithium powder and graphite-or graphene powder in the presence of the Si powder. The grinding can take place by mortar and pestle on a laboratory scale. However, the conversion preferably takes place in a mechanical mill, for example, a rod mill, oscillating mill or ball mill. The conversion is especially advantageously carried out in a planet ball mill. To this end, e.g., the planet ball mill Pulverisette 7 premium line from the Fritsch company can be used on a laboratory scale. When using planet ball mills very advantageously short reaction times of <10 h, frequently even <1 h can be surprisingly achieved.
- The mixture of lithium powder and graphite powder is preferably ground in the dry state. However, a fluid which is inert to both substances can also be added up to a weight ratio of up to 1:1 (sum of Li+C+Si:fluid). The inert fluid is preferably a non-aqueous hydrocarbon solvent, e.g., a liquid alkane or alkane mixture or an aromatic hydrocarbon mixture. The vigorousness of the grinding process is dampened and the graphite particles are groundless strongly by the addition of solvents.
- The grinding time is a function of various requirements and process parameters:
- weight ratio of grinding balls to product mixture
- type of grinding balls (e.g., hardness and density)
- intensity of the grinding (frequency of rotation of the grinding plate)
- reactivity of the lithium powder (e.g., type of coating)
- weight ratio of Li:C
- product-specific material properties
- desired particle size, etc.
- The conditions can be discovered by a person skilled in the art by simple optimizing experiments. In general, the grinding times fluctuate between 5 minutes and 24 hours, preferably between 10 minutes and 10 hours. After the end of the mechanochemical conversion a composite is present consisting of lithiated or partially lithiated graphite/graphene powder, largely unchanged Si-Powder and lithium metallic remainders.
- These lithiated or partially lithiated composite powders are “active” to environmental conditions (air and water) and to many functionalized solvents (e.g., NMP) and liquid electrolyte solutions, i.e. they react or decompose upon rather long exposure times. When stored in normal air the contained lithium reacts under the development of hydrogen to thermodynamically stable salts such as lithium hydroxide, lithium oxide and/or lithium carbonate. In order to at least largely avoid this disadvantage, the lithiated or partially lithiated composite powders can be stabilized by a second process step, a coating method. To this end the lithiated or partially lithiated composite powder is passivated with a gaseous or liquid coating agent. The coating agents used contain, compared to metallic lithium and lithium graphite intercalation compounds or lithium graphene intercalation compounds, reactive functional groups or molecular constituents and they therefore react with the lithium available on the surface. The conversion of the lithium-containing surface zone takes place under the formation of lithium salts such as, e.g., lithium carbonate, lithium chloride, lithium hydroxide, lithium alcoholates, lithium carboxylates, etc.) which are non-reactive or only slightly reactive to air (therefore thermodynamically stable). In this coating procedure the greatest part of the lithium which is not present on the particle surface (e.g. of the intercalated component) remains in active form, i.e., with an electrochemical potential of ≤1 V vs. Li/Li+. Such coating means are known from lithium ion battery technology as in-situ film producers (also designated as a SEI producers) for the negative electrodes and are described, for example, in the following survey article: A. Lex-Balducci, W. Henderson, S. Passerini, Electrolytes for Lithium Ion Batteries, in Lithium-Ion Batteries, Advanced Materials and Technologies, X. Yuan, H. Liu and J. Zhang (Hrsg.), CRC Press Boca Raton, 2012, p. 147-196. Coating agents used are cited by way of example in the following. Suitable gases are N2, CO2, CO, O2, N2O, NO, NO2, HF, F2, PF3, PF5, POF3and the like. Liquid coating agents used are, for example: carbonic acid esters (e.g., vinylene carbonate (VC), vinyl ethylene carbonate (VEC) ,ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), fluoroethylene carbonate (FEC)); lithium chelateoborate solutions (e.g., lithium bis(oxalato)borate (LiBOB), lithium bis(salicylato)borate (LiBSB), lithium bis(malonato)borate (LiBMB), lithium difluorooxalatoborate (LiDFOB) as solutions in organic solvents, preferably selected from: oxygen-containing heterocycles such as THF, 2-methyl-FHF, dioxolan; carbonic acid esters (carbonates) such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and/or ethyl methyl carbonate; nitriles such as acetonitrile, glutarodinitrile; carboxylic acid esters such as ethylacetate, butylformiate and ketones such as acetone, butanone; sulfur-organic compounds (e.g., sulfites, (vinylethylene sulfite, ethylene sulfite); sulfones, sultones and the like); N-containing organic compounds (e.g., pyrrole, pyridine, vinylpyridine, picolines, 1-vinyl-2-pyrrolidinone); phosphoric acid; organic, phosphorus-containing compounds (e.g., vinyl phosphonic acid); fluorine-containing organic and inorganic compounds (e.g., partially fluorinated hydrocarbons, BF3, LiPF6, LiBF4), silicon-containing compounds (e.g., silicon oils, alkyl siloxanes) among others.
- When using liquid coating agents the coating process generally takes place under an atmosphere of inert gas (e.g., argon protective atmosphere) at temperatures between 0 and 150° C. In order to increase the contact between the coating agent and the lithiated or partially lithiated composite powder, mixing or agitating conditions are advantageous. The necessary contact time between the coating agent and the lithiated or partially lithiated composite powder is a function of the reactivity of the coating agent, of the prevailing temperature and of other process parameters. In general, times between 1 minute and 24 hours are appropriate.
- The coating not only improves the handling properties and the safety in the production of electrodes (generally anodes) but also the properties of use in an electrochemical battery cell. When pre-coated anode materials are used, the in situ formation of an SEI (solid electrolyte interface) is eliminated upon contact of the lithiated or partially lithiated composite anode material with the liquid electrolyte of the battery cell. The anode filming brought about outside of the electrochemical cell by pre-coating corresponds in its properties to a so-called artificial SEI. In the ideal case the otherwise necessary forming process of the electrochemical cell is eliminated or it is at least simplified.
- The composite products lithiated or partially lithiated and stabilized according to the above-described method can be used to produce battery electrodes. For this, they are mixed and homogenized under inert or dry spatial conditions with at least one binder material and optionally with a conductivity-improving additive (e.g., blacks or metallic powder, e.g., Ni powder or Ni foam) and with an organic solvent and this dispersion is applied by a coating method (casting method, spin coating or airbrush method) onto a current arrester and dried. The stabilized lithiated or partially lithiated composite powders produced according to the method of the invention are surprisingly not very reactive to N-methylpyrrolidone (NMP) and to other functionalized, organic solvents. Therefore, they can be processed with NMP and the binder material polyvinylidene fluoride (PVdF) to a castable or sprayable dispersion. Other examples for suitable binder materials are, among others: carboxymethyl cellulose (CMC), polyisobutylene (e.g., OPPANOL of the BASF Company), alginic acid.
- In a preferred variant of the method according to the invention the described, non-coated, lithiated or partially lithiated composites are subjected following the mechanochemical conversion to a temperature step at temperatures between 100 and 350° C., preferably between 150 and 250° C. During a tempering time of 5 minutes to 24 h a conversion takes place between the lithiated or partially lithiated graphite-/graphene compounds and optionally any elementary (metallic) lithium still present to alloys of lithium and silicon (lithium silicides, e.g. Li7Si3). Upon maintaining sufficient storage times at a certain temperature it is possible to extract all lithium intercalated in the graphite or graphene and to use it for the production of the lithium silicides. In this manner a silicide composite is produced in the extreme case which consists of lithium-free or very lithium-poor graphite/graphene and lithium silicides. The exact composition results from the stoichiometry of the reaction batch.
- In a variant of a method the silicide composite materials of the invention can also be produced by mixing separately produced, powdery LiCo intercalation compounds (o=30 to 6) with silicon powder (1-100 μm particle size) in the desired molar ratio and in possibly a subsequent thermolysis phase (130 to 350° C. for 5 min to 24 h, preferably 140-300° C. Use of the term “LiCo intercalation compounds (o=30 to 6)” means that lithium atoms are intercalated in graphite in a molar ration from 1:30 up to 1:6.
- It was surprisingly found that the non-coated, lithiated or partially lithiated composites as well as the silicide composites in contact with electrolytic solutions and carbonate solvents are more stable than pure lithium-graphite intercalation compounds. As an example, the following beginnings of an exothermal decomposition reaction can be observed for composites produced in the molar ratio Si:Li:C=1:2.7:3.9, when stored in a mixture of ethylene carbonate/ethyl methyl carbonate (EC/EMC, 1:1 w/w) in DSC experiments with the Radex system of the Systag company:
- Non-coated lithium graphite intercalation compound LiC6 (Li content=8.8 weight %) Tonset=130° C.
- Non-thermolyzed Li/Si/C—composite with the composition Li2.7SiC3.9 (Li content=28.5 weight %): Tonset=170° C.
- At 150° C. 4 hours thermolyzed Li/Si/C—composite with the composition Li2.7SiC3.9 (Li content=28.5 weight %): Tonset=140° C.
- At 250° C. 10 hours thermolyzed Li/Si/C—composite with the composition Li2.7SiC3.9 (Li content=28.5 weight %): Tonset=150° C.
- In spite of the lithium concentration in the composite materials according to the invention, which is significantly higher in comparison to LiC6, the materials according to the invention have an improved thermal stability compared to an EC/EMC mixture.
- Furthermore, it was surprisingly found that the composite materials are not self-igniting in air as a rule. This is the opposite of the behavior of non-coated LiC6.
- The electrochemical rest potential of the composite material of the invention is below about 2 V, preferably below 1 V measured against Li/Li+.
- The composite materials according to the invention can be used as high-capacitive anode materials for galvanic cells with non-aqueous electrolytes, for example lithium batteries.
- A mixture consisting of:
- 1.80 g (64 mmol) Si powder (supplier Wacker, Si content 89.4 wt %, D50=58 μm)
- 1.16 g (167 mmol) Li powder (Rockwood Lithium, non-coated, Li content >99 wt %,
- D50=105 μm)
- 3.00 g (250 mmol) graphite powder (SLP 30 from the Timcal company)
was ground together with 26 ZrO2 balls, diameter 3 mm 4 h at 400 rpm in a reversion operation in a planet ball mill Pulverisette P 7 with a zirconium oxide grinding cup from the Fritsch company in a glove box filled with Ar. This composition of mixture is within the claimed ranges: - 64 mmol Si can accommodate max. 282 mmol Li according to the limiting stoichiometry Li22Si5
- 250 mmol graphite can accommodate max. 42 mmol Li according to the limiting stoichiometry LiC6.
The maximum Li uptake capacity of this quantity of mixture is therefore 324 mmol, which is 52 molar % of the lithium metal quantity (167 mmol) used. - 5.56 g of a golden-brown powder was obtained. The phases LiC12, LiC6, Si metal, and Li metal can be identified in this product by powder x-ray diffractometry. Graphite and Li/Si alloys cannot be identified.
- The product surprisingly proved to be non-self-igniting in air. It vigorously reacts with N-methylpyrrolidone after a short time.
- 1.05 g of a mixture produced according to example 1 are thermolyzed in closed steel autoclaves in Ar protective gas for 4 hours at 150° C. Subsequently, the following phases can be identified by XRD: lithium silicides, graphite and Si (reduced intensity). Metallic lithium cannot be identified.
- The product is not self-igniting in air. It reacts mildly with NMP at room temperature.
- 1.16 g of a mixture produced according to example 1 are thermolyzed in closed steel autoclaves in Ar protective gas for 10 hours at 250° C. Subsequently, the following phases can be identified by XRD: lithium silicides (elevated intensity), graphite and Si (greatly reduced intensity). Metallic lithium cannot be identified.
- The product is not self-igniting in air. It reacts only extremely weakly with NMP at room temperature.
- The examples show the production of Li/C/Si composites with a high lithium content (52 wt % of maximum lithium capacity) and their qualitative composition. A thermal post-treatment improves the stability to reactive solvents shown, for example, on a mixture with N-methyl pyrrolidone.
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CN113497225A (en) * | 2020-04-07 | 2021-10-12 | 丰田自动车株式会社 | Method for producing active material |
WO2023273265A1 (en) * | 2021-06-30 | 2023-01-05 | 广东邦普循环科技有限公司 | Pre-lithiated graphene, and preparation method therefor and application thereof |
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CN113497225A (en) * | 2020-04-07 | 2021-10-12 | 丰田自动车株式会社 | Method for producing active material |
CN111525108A (en) * | 2020-04-20 | 2020-08-11 | 南昌大学 | Synthesis method of carbon-coated silicon negative electrode material |
WO2023273265A1 (en) * | 2021-06-30 | 2023-01-05 | 广东邦普循环科技有限公司 | Pre-lithiated graphene, and preparation method therefor and application thereof |
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