CN117410561A - Electrolyte additive, electrolyte containing same and lithium ion battery - Google Patents
Electrolyte additive, electrolyte containing same and lithium ion battery Download PDFInfo
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- CN117410561A CN117410561A CN202311344096.9A CN202311344096A CN117410561A CN 117410561 A CN117410561 A CN 117410561A CN 202311344096 A CN202311344096 A CN 202311344096A CN 117410561 A CN117410561 A CN 117410561A
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- Prior art keywords
- electrolyte
- carbonate
- lithium
- trimethylsilane
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 97
- 239000002000 Electrolyte additive Substances 0.000 title claims abstract description 15
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 15
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 12
- -1 phenyl isocyanate compound Chemical class 0.000 claims abstract description 30
- 239000000654 additive Substances 0.000 claims abstract description 8
- 125000006527 (C1-C5) alkyl group Chemical group 0.000 claims abstract description 3
- 125000003545 alkoxy group Chemical group 0.000 claims abstract description 3
- 125000003709 fluoroalkyl group Chemical group 0.000 claims abstract description 3
- 229910052736 halogen Inorganic materials 0.000 claims abstract description 3
- 150000002367 halogens Chemical class 0.000 claims abstract description 3
- 125000001183 hydrocarbyl group Chemical group 0.000 claims abstract description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims abstract description 3
- 229930195735 unsaturated hydrocarbon Natural products 0.000 claims abstract description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 34
- 229910003002 lithium salt Inorganic materials 0.000 claims description 25
- 159000000002 lithium salts Chemical class 0.000 claims description 25
- MWKJTNBSKNUMFN-UHFFFAOYSA-N trifluoromethyltrimethylsilane Chemical compound C[Si](C)(C)C(F)(F)F MWKJTNBSKNUMFN-UHFFFAOYSA-N 0.000 claims description 25
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 18
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 18
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 18
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 16
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 13
- 229910052744 lithium Inorganic materials 0.000 claims description 13
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 6
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 6
- 229910019142 PO4 Inorganic materials 0.000 claims description 6
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 6
- 239000010452 phosphate Substances 0.000 claims description 6
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000003960 organic solvent Substances 0.000 claims description 5
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 4
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 claims description 4
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- VEWLDLAARDMXSB-UHFFFAOYSA-N ethenyl sulfate;hydron Chemical compound OS(=O)(=O)OC=C VEWLDLAARDMXSB-UHFFFAOYSA-N 0.000 claims description 4
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 claims description 4
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 claims description 4
- 239000007774 positive electrode material Substances 0.000 claims description 3
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 claims description 2
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 2
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 2
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 claims description 2
- GWAOOGWHPITOEY-UHFFFAOYSA-N 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide Chemical compound O=S1(=O)CS(=O)(=O)OCO1 GWAOOGWHPITOEY-UHFFFAOYSA-N 0.000 claims description 2
- HNAGHMKIPMKKBB-UHFFFAOYSA-N 1-benzylpyrrolidine-3-carboxamide Chemical compound C1C(C(=O)N)CCN1CC1=CC=CC=C1 HNAGHMKIPMKKBB-UHFFFAOYSA-N 0.000 claims description 2
- HFZLSTDPRQSZCQ-UHFFFAOYSA-N 1-pyrrolidin-3-ylpyrrolidine Chemical compound C1CCCN1C1CNCC1 HFZLSTDPRQSZCQ-UHFFFAOYSA-N 0.000 claims description 2
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 claims description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 2
- RJUFJBKOKNCXHH-UHFFFAOYSA-N Methyl propionate Chemical compound CCC(=O)OC RJUFJBKOKNCXHH-UHFFFAOYSA-N 0.000 claims description 2
- XNENYPKLNXFICU-UHFFFAOYSA-N P(O)(O)O.C[SiH](C)C.C[SiH](C)C.C[SiH](C)C Chemical compound P(O)(O)O.C[SiH](C)C.C[SiH](C)C.C[SiH](C)C XNENYPKLNXFICU-UHFFFAOYSA-N 0.000 claims description 2
- BTGRAWJCKBQKAO-UHFFFAOYSA-N adiponitrile Chemical compound N#CCCCCC#N BTGRAWJCKBQKAO-UHFFFAOYSA-N 0.000 claims description 2
- OBNCKNCVKJNDBV-UHFFFAOYSA-N butanoic acid ethyl ester Natural products CCCC(=O)OCC OBNCKNCVKJNDBV-UHFFFAOYSA-N 0.000 claims description 2
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims description 2
- VUPKGFBOKBGHFZ-UHFFFAOYSA-N dipropyl carbonate Chemical compound CCCOC(=O)OCCC VUPKGFBOKBGHFZ-UHFFFAOYSA-N 0.000 claims description 2
- ZTOMUSMDRMJOTH-UHFFFAOYSA-N glutaronitrile Chemical compound N#CCCCC#N ZTOMUSMDRMJOTH-UHFFFAOYSA-N 0.000 claims description 2
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 2
- 229940017219 methyl propionate Drugs 0.000 claims description 2
- KKQAVHGECIBFRQ-UHFFFAOYSA-N methyl propyl carbonate Chemical compound CCCOC(=O)OC KKQAVHGECIBFRQ-UHFFFAOYSA-N 0.000 claims description 2
- 239000002153 silicon-carbon composite material Substances 0.000 claims description 2
- IAHFWCOBPZCAEA-UHFFFAOYSA-N succinonitrile Chemical compound N#CCCC#N IAHFWCOBPZCAEA-UHFFFAOYSA-N 0.000 claims description 2
- HXJUTPCZVOIRIF-UHFFFAOYSA-N sulfolane Chemical compound O=S1(=O)CCCC1 HXJUTPCZVOIRIF-UHFFFAOYSA-N 0.000 claims description 2
- YFNKIDBQEZZDLK-UHFFFAOYSA-N triglyme Chemical compound COCCOCCOCCOC YFNKIDBQEZZDLK-UHFFFAOYSA-N 0.000 claims description 2
- QKBJDEGZZJWPJA-UHFFFAOYSA-N ethyl propyl carbonate Chemical compound [CH2]COC(=O)OCCC QKBJDEGZZJWPJA-UHFFFAOYSA-N 0.000 claims 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 abstract description 8
- 230000000996 additive effect Effects 0.000 abstract description 5
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 abstract 1
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 32
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 16
- 229910052786 argon Inorganic materials 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 16
- 238000002360 preparation method Methods 0.000 description 16
- 238000003756 stirring Methods 0.000 description 16
- 230000014759 maintenance of location Effects 0.000 description 9
- 229940125904 compound 1 Drugs 0.000 description 8
- 238000000034 method Methods 0.000 description 6
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 5
- 239000007773 negative electrode material Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000010280 constant potential charging Methods 0.000 description 4
- 230000001351 cycling effect Effects 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- DGTNSSLYPYDJGL-UHFFFAOYSA-N phenyl isocyanate Chemical class O=C=NC1=CC=CC=C1 DGTNSSLYPYDJGL-UHFFFAOYSA-N 0.000 description 4
- YZSKZXUDGLALTQ-UHFFFAOYSA-N [Li][C] Chemical compound [Li][C] YZSKZXUDGLALTQ-UHFFFAOYSA-N 0.000 description 3
- 239000007770 graphite material Substances 0.000 description 3
- QPJSUIGXIBEQAC-UHFFFAOYSA-N n-(2,4-dichloro-5-propan-2-yloxyphenyl)acetamide Chemical compound CC(C)OC1=CC(NC(C)=O)=C(Cl)C=C1Cl QPJSUIGXIBEQAC-UHFFFAOYSA-N 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000010405 anode material Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 238000010277 constant-current charging Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000006138 lithiation reaction Methods 0.000 description 2
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910001428 transition metal ion Inorganic materials 0.000 description 2
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 230000010718 Oxidation Activity Effects 0.000 description 1
- SYRDSFGUUQPYOB-UHFFFAOYSA-N [Li+].[Li+].[Li+].[O-]B([O-])[O-].FC(=O)C(F)=O Chemical compound [Li+].[Li+].[Li+].[O-]B([O-])[O-].FC(=O)C(F)=O SYRDSFGUUQPYOB-UHFFFAOYSA-N 0.000 description 1
- ZJPPTKRSFKBZMD-UHFFFAOYSA-N [Li].FS(=N)F Chemical compound [Li].FS(=N)F ZJPPTKRSFKBZMD-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229940125782 compound 2 Drugs 0.000 description 1
- 229940126214 compound 3 Drugs 0.000 description 1
- 229940125898 compound 5 Drugs 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- QQUZYDCFSDMNPX-UHFFFAOYSA-N ethene;4-methyl-1,3-dioxolan-2-one Chemical compound C=C.CC1COC(=O)O1 QQUZYDCFSDMNPX-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 239000012948 isocyanate Substances 0.000 description 1
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 description 1
- 150000002513 isocyanates Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 125000002023 trifluoromethyl group Chemical group FC(F)(F)* 0.000 description 1
- 125000000026 trimethylsilyl group Chemical group [H]C([H])([H])[Si]([*])(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
Abstract
The invention provides an electrolyte additive, an electrolyte containing the additive and a lithium ion battery, and relates to the technical field of lithium ion batteries. The electrolyte additive comprises a phenyl isocyanate compound shown in a structural formula I:R 1 ‑R 5 one or more selected from hydrogen atom, C1-C5 alkyl, C1-C5 fluoroalkyl, C1-C5 alkoxy, substituted or unsubstituted C2-C6 unsaturated hydrocarbon group, halogen. The electrolyte provided by the invention can effectively promote the formation of a stable SEI film on the surface of the silicon-carbon negative electrode, improves the cycle performance of the silicon-carbon negative electrode, and is especially suitable for ternary/silicon-carbon lithium ion battery systems.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte additive, an electrolyte containing the additive and a lithium ion battery.
Background
Along with the continuous improvement of the energy density of the power battery, the traditional graphite material is difficult to meet the design requirement of the high-specific-energy battery, the theoretical capacity of the Si negative electrode material can reach 4200mAh/g, which is more than 10 times of that of the graphite material, and the lithium intercalation potential is close to that of the graphite material, so that the Si negative electrode material is an ideal choice of the next-generation high-capacity negative electrode material.
The high-nickel anode material has higher oxidation activity in a low lithiation degree state or a high working voltage state, and the silicon-carbon anode material has larger volume effect in the lithiation/delithiation process, so that the stability of an electrode/electrolyte interface is reduced, the electrolyte is severely decomposed, and the reversible capacity is rapidly reduced. In addition, trace amount of water (H) 2 O) and lithium hexafluorophosphate (LiPF) 6 ) The base electrolyte generates hydrofluoric acid (HF), the high nickel cathode material may be eroded during the cycle, causing dissolution of transition metal ions, which will destroy the structure of the cathode material, and transition metal ions will also migrate and deposit on the anode interface, which will affect the SEI film of the anode. Therefore, the construction of an effective interfacial protection film by electrolyte additives is one of the most cost-effective methods to solve these problems.
Based on the above, it is necessary to provide an electrolyte additive and an electrolyte for improving the cycle performance of a ternary/silicon carbon lithium ion battery, so as to improve the problems of the destruction of an SEI film in the cycle process of a silicon carbon negative electrode material and the generation of HF in the cycle process, and further improve the technical limitation problem of the existing ternary/silicon carbon lithium ion battery.
Disclosure of Invention
Based on the technical problems in the background technology, the invention provides an electrolyte additive, an electrolyte containing the additive and a lithium ion battery.
The invention provides an electrolyte additive, which comprises a phenyl isocyanate compound shown in a structural formula I:
R 1 -R 5 one or more selected from hydrogen atom, C1-C5 alkyl, C1-C5 fluoroalkyl, C1-C5 alkoxy, substituted or unsubstituted C2-C6 unsaturated hydrocarbon group, halogen.
Preferably, the phenyl isocyanate compound is selected from one or more of the compounds 1 to 5:
the invention also provides an electrolyte comprising lithium salt, an organic solvent, the electrolyte additive, (trifluoromethyl) trimethylsilane and other additives.
The structural formula of the (trifluoromethyl) trimethylsilane is as follows:
preferably, the other additive is selected from one or more of vinyl sulfate, vinylene carbonate, methylene methane disulfonate, 1, 3-propane sultone, tris (trimethylsilane) phosphite, propenyl-1, 3-sultone, ethylene carbonate.
Preferably, the mass of the (trifluoromethyl) trimethylsilane accounts for 0.1-3.5% of the total mass of the electrolyte.
Preferably, the mass of the isocyanate benzene ester compound accounts for 0.1-3.5% of the total mass of the electrolyte.
Preferably, the mass of the other additive accounts for 0.1-5% of the total mass of the electrolyte.
Preferably, the mass of the lithium salt accounts for 6.25-18.75% of the total mass of the electrolyte; the mass of the organic solvent accounts for 75-90% of the total mass of the electrolyte.
Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluoro (oxalato) phosphate, lithium difluorophosphate, lithium oxalato phosphate, lithium bisoxalato borate, lithium difluorooxalato borate, lithium tetrafluoro borate and lithium difluorosulfimide.
Preferably, the concentration of the lithium salt in the electrolyte is 0.5M to 1.5M.
More preferably, the concentration of the lithium salt in the electrolyte is 0.5M, 0.75M, 1M, 1.3M or 1.5M.
Preferably, the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylethyl carbonate, methylpropyl carbonate, ethylene propylene carbonate, dimethyl ether, diethyl ether, adiponitrile, succinonitrile, glutaronitrile, dimethyl sulfoxide, sulfolane, 1, 4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate, ethyl butyrate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and 1, 3-dioxolane.
The invention also provides a lithium ion battery, which comprises a positive plate, a negative plate, a diaphragm, a battery shell and the electrolyte.
Preferably, the positive plate is a ternary positive electrode material with the molar ratio of Ni to Co to Mn of 5:3:2, 6:2:2 or 8:1:1, and the negative plate is a silicon-carbon composite material.
The beneficial effects of the invention are as follows:
the electrolyte additive comprises (trifluoromethyl) trimethylsilane and phenyl isocyanate compounds, wherein trimethylsilyl group in the (trifluoromethyl) trimethylsilane can stabilize LiPF 6 Synergistic action with isocyanate groups in isocyanate-based compounds to capture H 2 O and remove HF generated in the battery circulation process, improve the stability of the electrolyte at high temperature, and reduce the subsequent damage to the structure and composition of the CEI layer of the battery anode; the trifluoromethyl in the (trifluoromethyl) trimethylsilane is easy to form a film on a negative electrode, improves the oxidation resistance of a positive electrode, is easier to form an SEI film containing LiF, improves the stability of an electrode/electrolyte interface, and improves the cycling stability of a silicon-carbon negative electrode.
Detailed Description
The technical scheme of the invention is described in detail through specific embodiments.
In the following examples and comparative examples, the structural formula of the phenyl isocyanate compound used is shown in Table 1:
TABLE 1 phenyl isocyanate compounds 1-5 structural formulas
Example 1
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, and then adding 3.0% (trifluoromethyl) trimethylsilane and 1.0% of compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 2
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 2.0% of (trifluoromethyl) trimethylsilane and 1.0% of compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 3
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, and then adding 1.0% of (trifluoromethyl) trimethylsilane and 3.0% of compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 4
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 2.5% of (trifluoromethyl) trimethylsilane and 0.5% of compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 5
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 0.5% of (trifluoromethyl) trimethylsilane and 2.5% of compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 6
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 2.0% of (trifluoromethyl) trimethylsilane and 1.0% of compound 2 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 7
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 2.0% of (trifluoromethyl) trimethylsilane and 1.0% of compound 3 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 8
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 2.0% of (trifluoromethyl) trimethylsilane and 1.0% of compound 4 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 9
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 2.0% of (trifluoromethyl) trimethylsilane and 1.0% of compound 5 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 10
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.0M lithium hexafluorophosphate and 0.3M lithium bis (fluorosulfonyl) imide, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, and then adding 2.0% of (trifluoromethyl) trimethylsilane and 1.0% of compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Example 11
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% lithium difluorooxalato borate and 1.0% vinyl sulfate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 2.0% (trifluoromethyl) trimethylsilane and 1.0% compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Comparative example 1
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, and then adding 3.0% of (trifluoromethyl) trimethylsilane according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Comparative example 2
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, adding 3.0% of compound 1 according to the total mass of the electrolyte, and uniformly stirring to obtain the battery electrolyte.
Comparative example 3
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, and uniformly stirring to obtain the battery electrolyte.
Comparative example 4
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.3M lithium hexafluorophosphate, adding 0.5% lithium difluorooxalate borate and 1.0% vinyl sulfate according to the total mass of the electrolyte after the lithium salt is completely dissolved, and uniformly stirring to obtain the battery electrolyte.
Comparative example 5
Preparation of electrolyte: in a glove box filled with argon, uniformly mixing ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, propylene carbonate and fluoroethylene carbonate according to a mass ratio of 20:10:50:8:12, adding 1.0M lithium hexafluorophosphate and 0.3M lithium bis (fluorosulfonyl) imide, adding 0.5% of ethylene carbonate and 1.0% of lithium difluorophosphate according to the total mass of the electrolyte after the lithium salt is completely dissolved, and uniformly stirring to obtain the battery electrolyte.
And (3) battery assembly: liNi is added to 0.8 Co 0.1 Mn 0.1 O 2 The positive electrode material and the silicon carbon negative electrode material (400 mAh/g) were paired according to N/p=1.1 to assemble a 3.4Ah soft pack battery, and the electrolytes in examples 1 to 11 and comparative examples 1 to 5 were used, respectively.
The assembled batteries of examples 1 to 11 and comparative examples 1 to 5 were subjected to normal temperature cycle and high temperature cycle tests, respectively, and 3 batteries were tested in parallel for each of the assembled batteries of example/comparative example under each test, and the test results are shown in table 2.
The normal temperature cycle test conditions were as follows: in a constant temperature cabinet at 25 ℃,1C is discharged to 2.75V,1C constant current charging is carried out to 4.25V, constant voltage charging is carried out to 0.05C, the constant voltage charging is recorded as one circle of circulation, the 1 st-5 th circle of circulation discharge capacity is taken as initial discharge capacity, when the circulation is carried out to 800 circles of circulation, 800 th circle of circulation discharge capacity is calculated, and the calculated capacity retention rate is compared with the initial capacity. The calculation formula is as follows: the 800 th cycle capacity retention= (800 th cycle discharge capacity/initial discharge capacity) ×100%.
The high temperature cycle test conditions were as follows: in a 45 ℃ incubator, 1C is discharged to 2.75V,1C constant current charging is carried out to 4.25V, constant voltage charging is carried out to 0.05C, the constant voltage charging is recorded as one circle of circulation, the 1 st-5 th circle of circulation discharge capacity is taken as initial discharge capacity, when the circulation is carried out to 500 circles of circulation, the 500 th circle of circulation discharge capacity is calculated, and the calculated 500 th circle of circulation discharge capacity is compared with the initial capacity to calculate the capacity retention rate. The calculation formula is as follows: the 500 th cycle capacity retention= (500 th cycle discharge capacity/initial discharge capacity) ×100%.
Table 2 battery test results for examples 1-11 and comparative examples 1-5
| Examples | Battery capacity retention rate after 800 cycles at normal temperature | Battery capacity retention after 500 cycles at high temperature |
| Example 1 | 94.07％ | 88.84％ |
| Example 2 | 94.58％ | 89.97％ |
| Example 3 | 92.38％ | 87.30％ |
| Example 4 | 94.35％ | 89.21％ |
| Example 5 | 92.47％ | 88.09％ |
| Example 6 | 93.13％ | 88.45％ |
| Example 7 | 92.74％ | 87.91％ |
| Example 8 | 93.15％ | 87.89％ |
| Example 9 | 92.37％ | 87.26％ |
| Example 10 | 93.49％ | 88.57％ |
| Example 11 | 93.38％ | 88.62％ |
| Comparative example 1 | 90.77％ | 84.22％ |
| Comparative example 2 | 89.23％ | 83.98％ |
| Comparative example 3 | ＜80％ | ＜80％ |
| Comparative example 4 | ＜80％ | ＜80％ |
| Comparative example 5 | ＜80％ | ＜80％ |
As shown in the results of Table 2, the electrolyte prepared by the invention by combining (trifluoromethyl) trimethylsilane and phenyl isocyanate compounds has good cycling stability, the capacity retention rate is 92.37-94.58% after cycling at 25 ℃ for 800 circles, and the capacity retention rate is 87.26-89.97% after cycling at 45 ℃ for 500 circles. Compared with examples 1-11, if only (trifluoromethyl) trimethylsilane or only phenyl isocyanate compound is used, the prepared battery has poor normal-temperature cycle. Compared with examples 1-11, the prepared battery has the retention rate lower than 80% after 800 cycles at 25 ℃ and 500 cycles at 45 ℃ without adding (trifluoromethyl) trimethylsilane and phenyl isocyanate compounds or further changing the types of lithium salts.
From the test results of the assembled batteries of examples 1-11 and comparative examples 1-5, it can be observed that the electrolyte prepared by the matching of the (trifluoromethyl) trimethylsilane and the phenyl isocyanate compound under the condition of 2.75-4.25V can adapt to the volume change of the silicon-carbon material in the circulating process, is beneficial to improving the circulating stability of the silicon-carbon material, ensures that the battery has excellent performance in the temperature range of 25-45 ℃, and obviously improves the technical limitation problem of the existing ternary/silicon-carbon lithium ion battery.
In summary, the electrolyte additive and the electrolyte containing the same provided by the invention can effectively improve the SEI film stability and cycle performance of a ternary/silicon carbon lithium ion battery.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.
Claims (10)
1. The electrolyte additive is characterized by comprising an isocyanate benzene ester compound shown in a structural formula I:
R 1 -R 5 one or more selected from hydrogen atom, C1-C5 alkyl, C1-C5 fluoroalkyl, C1-C5 alkoxy, substituted or unsubstituted C2-C6 unsaturated hydrocarbon group, halogen.
2. The electrolyte additive according to claim 1, wherein the phenyl isocyanate compound is one or more selected from the group consisting of compounds 1 to 5:
3. an electrolyte comprising a lithium salt, an organic solvent, the electrolyte additive of any one of claims 1-2, and (trifluoromethyl) trimethylsilane, wherein the (trifluoromethyl) trimethylsilane has the following structural formula:
4. an electrolyte according to claim 3, further comprising other additives selected from one or more of vinyl sulfate, vinylene carbonate, methylene methane disulfonate, 1, 3-propane sultone, tris (trimethylsilane) phosphite, propenyl-1, 3-sultone, ethylene carbonate; the mass of the other additives accounts for 0.1-5% of the total mass of the electrolyte.
5. An electrolyte according to claim 3, wherein the mass of (trifluoromethyl) trimethylsilane is 0.1 to 3.5% of the total mass of the electrolyte; the mass of the isocyanate benzene ester compound accounts for 0.1-3.5% of the total mass of the electrolyte.
6. An electrolyte according to claim 3, wherein the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium difluorobis-oxalato phosphate, lithium tetrafluorooxalato phosphate, lithium difluorophosphate, lithium oxalato phosphate, lithium bis-oxalato borate, lithium difluorooxalato borate, lithium tetrafluoroborate and lithium difluorosulfonimide.
7. An electrolyte according to claim 3, wherein the concentration of the lithium salt in the electrolyte is 0.5M to 1.5M.
8. An electrolyte according to claim 3, wherein the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylethyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, dimethyl ether, diethyl ether, adiponitrile, succinonitrile, glutaronitrile, dimethyl sulfoxide, sulfolane, 1, 4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate, ethyl butyrate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and 1, 3-dioxolane.
9. A lithium ion battery comprising a positive plate, a negative plate, a separator and a battery shell, and further comprising the electrolyte as claimed in any one of claims 3-8.
10. The lithium ion battery of claim 9, wherein the positive electrode sheet is a ternary positive electrode material with a molar ratio of Ni to Co to Mn of 5:3:2, 6:2:2 or 8:1:1, and the negative electrode sheet is a silicon-carbon composite material.
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