CN117613383A - Electrolyte additive, electrolyte containing same and lithium battery - Google Patents
Electrolyte additive, electrolyte containing same and lithium battery Download PDFInfo
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- CN117613383A CN117613383A CN202311519516.2A CN202311519516A CN117613383A CN 117613383 A CN117613383 A CN 117613383A CN 202311519516 A CN202311519516 A CN 202311519516A CN 117613383 A CN117613383 A CN 117613383A
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- additive
- electrolyte
- silane
- battery
- lithium battery
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 37
- 239000002000 Electrolyte additive Substances 0.000 title claims abstract description 20
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 14
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 14
- 239000000654 additive Substances 0.000 claims abstract description 53
- 230000000996 additive effect Effects 0.000 claims abstract description 45
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 31
- 229910000077 silane Inorganic materials 0.000 claims abstract description 31
- -1 fluoroalkynyl Chemical group 0.000 claims abstract description 7
- 125000000304 alkynyl group Chemical group 0.000 claims abstract description 4
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 3
- 125000003709 fluoroalkyl group Chemical group 0.000 claims abstract description 3
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims abstract description 3
- 229910003002 lithium salt Inorganic materials 0.000 claims description 24
- 159000000002 lithium salts Chemical class 0.000 claims description 24
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 16
- 239000011737 fluorine Substances 0.000 claims description 16
- 229910052731 fluorine Inorganic materials 0.000 claims description 16
- 150000001875 compounds Chemical class 0.000 claims description 4
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 claims description 3
- 239000003960 organic solvent Substances 0.000 claims description 3
- 125000004169 (C1-C6) alkyl group Chemical group 0.000 claims description 2
- 125000003601 C2-C6 alkynyl group Chemical group 0.000 claims description 2
- 150000004996 alkyl benzenes Chemical class 0.000 claims description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 abstract description 10
- 238000003860 storage Methods 0.000 abstract description 10
- 238000000034 method Methods 0.000 abstract description 9
- 229910052799 carbon Inorganic materials 0.000 abstract description 7
- 230000000694 effects Effects 0.000 abstract description 6
- 229910052759 nickel Inorganic materials 0.000 abstract description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 4
- 230000006866 deterioration Effects 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 229910052710 silicon Inorganic materials 0.000 abstract description 3
- 239000010703 silicon Substances 0.000 abstract description 3
- 125000004423 acyloxy group Chemical group 0.000 abstract description 2
- 230000015556 catabolic process Effects 0.000 abstract description 2
- 238000006731 degradation reaction Methods 0.000 abstract description 2
- 125000000026 trimethylsilyl group Chemical group [H]C([H])([H])[Si]([*])(C([H])([H])[H])C([H])([H])[H] 0.000 abstract description 2
- 239000003795 chemical substances by application Substances 0.000 abstract 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000011203 carbon fibre reinforced carbon Substances 0.000 description 4
- 239000011267 electrode slurry Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- 229910013075 LiBF Inorganic materials 0.000 description 3
- 229910013870 LiPF 6 Inorganic materials 0.000 description 3
- 239000002033 PVDF binder Substances 0.000 description 3
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 230000001351 cycling effect Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 125000005373 siloxane group Chemical group [SiH2](O*)* 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- HNAGHMKIPMKKBB-UHFFFAOYSA-N 1-benzylpyrrolidine-3-carboxamide Chemical compound C1C(C(=O)N)CCN1CC1=CC=CC=C1 HNAGHMKIPMKKBB-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- 229910013716 LiNi Inorganic materials 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- ZJPPTKRSFKBZMD-UHFFFAOYSA-N [Li].FS(=N)F Chemical compound [Li].FS(=N)F ZJPPTKRSFKBZMD-UHFFFAOYSA-N 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- OBNCKNCVKJNDBV-UHFFFAOYSA-N butanoic acid ethyl ester Natural products CCCC(=O)OCC OBNCKNCVKJNDBV-UHFFFAOYSA-N 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229940125904 compound 1 Drugs 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 230000021615 conjugation Effects 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910021382 natural graphite Inorganic materials 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- 239000011255 nonaqueous electrolyte Substances 0.000 description 2
- 238000006864 oxidative decomposition reaction Methods 0.000 description 2
- 125000004430 oxygen atom Chemical group O* 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000002153 silicon-carbon composite material Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 1
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 description 1
- UHOPWFKONJYLCF-UHFFFAOYSA-N 2-(2-sulfanylethyl)isoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCS)C(=O)C2=C1 UHOPWFKONJYLCF-UHFFFAOYSA-N 0.000 description 1
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 description 1
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- JGFBQFKZKSSODQ-UHFFFAOYSA-N Isothiocyanatocyclopropane Chemical compound S=C=NC1CC1 JGFBQFKZKSSODQ-UHFFFAOYSA-N 0.000 description 1
- 229910015015 LiAsF 6 Inorganic materials 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910013684 LiClO 4 Inorganic materials 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 1
- 229910015643 LiMn 2 O 4 Inorganic materials 0.000 description 1
- 229910013290 LiNiO 2 Inorganic materials 0.000 description 1
- RJUFJBKOKNCXHH-UHFFFAOYSA-N Methyl propionate Chemical compound CCC(=O)OC RJUFJBKOKNCXHH-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 229920003235 aromatic polyamide Polymers 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- PWLNAUNEAKQYLH-UHFFFAOYSA-N butyric acid octyl ester Natural products CCCCCCCCOC(=O)CCC PWLNAUNEAKQYLH-UHFFFAOYSA-N 0.000 description 1
- ANTVXUWVWRKHPP-UHFFFAOYSA-N carbonic acid;pent-1-ene Chemical compound OC(O)=O.CCCC=C ANTVXUWVWRKHPP-UHFFFAOYSA-N 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229940126214 compound 3 Drugs 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- VUPKGFBOKBGHFZ-UHFFFAOYSA-N dipropyl carbonate Chemical compound CCCOC(=O)OCCC VUPKGFBOKBGHFZ-UHFFFAOYSA-N 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 1
- 229940017219 methyl propionate Drugs 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- UUIQMZJEGPQKFD-UHFFFAOYSA-N n-butyric acid methyl ester Natural products CCCC(=O)OC UUIQMZJEGPQKFD-UHFFFAOYSA-N 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 238000003797 solvolysis reaction Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- CWMFRHBXRUITQE-UHFFFAOYSA-N trimethylsilylacetylene Chemical group C[Si](C)(C)C#C CWMFRHBXRUITQE-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to the field of electrolyte, and provides an electrolyte additive, electrolyte containing the additive and a lithium battery, aiming at the problem of power performance degradation of the lithium battery when the high-temperature cycle and storage performance of a high-nickel/silicon carbon battery are improved, wherein the electrolyte additive comprises a silane additive, and the structure of the silane additive is shown as a formula (I):
Description
Technical Field
The invention relates to the field of electrolyte, in particular to an electrolyte additive, and an electrolyte and a lithium battery containing the electrolyte additive.
Background
The high-nickel silicon carbon system of the automobile power battery needs to ensure high-rate charge and discharge, namely high-power characteristics, and simultaneously has long service life and high-low temperature performance, so that the high-nickel silicon carbon system has higher requirements on the design of electrolyte. When the high-rate charge and discharge is carried out, the electrochemical reaction is violently carried out, so that the nickel of the positive electrode of the battery is dissolved out, the electrolyte is subjected to oxidative decomposition on the surface of the positive electrode, the silicon-carbon negative electrode is rapidly expanded and pulverized, the capacity of the battery is exerted and the retention rate is rapidly attenuated, and even the lithium precipitation phenomenon is possibly generated in the charging process; meanwhile, the heat generation of the battery core is obviously increased, the thermal runaway risk of the battery is increased, and potential safety hazards exist.
Aiming at the problems of nickel dissolution, silicon cathode expansion, capacity attenuation and safety which possibly occur in the high-power charge and discharge, the prior solution mainly comprises two types: 1. the positive and negative pole pieces are optimized, and the contact area between the positive and negative poles and the electrolyte is increased by reducing the particle size of the material, changing the shape of the material and other schemes, so that the rapid intercalation and deintercalation of lithium ions are promoted. 2. The electrolyte formulation is optimized, and film forming additives with interface improving effect, such as FEC and the like, are added, so that the method is the most direct and convenient method. For example, patent CN110600803a discloses a silane additive which can effectively reduce the moisture content and acidity in the electrolyte and improve the cycle performance of the cell at high temperature and high pressure. However, when the problems of positive electrode nickel dissolution, negative electrode silicon carbon negative electrode expansion and the like are solved through the use of the additive from the viewpoint of electrolyte, the storage performance is reduced, the cycle life is further reduced, and the requirements of high power, high safety, stable cycle life and the like cannot be met at the same time. There is a need for an ideal solution.
Disclosure of Invention
In order to solve the problem of deterioration of power performance of a lithium battery when high-temperature circulation and storage performance of a high-nickel/silicon carbon battery are improved, the invention provides an electrolyte additive, an electrolyte containing the electrolyte additive and the lithium battery, and a silane additive can obviously improve film forming performance, improve high-temperature performance and reduce gas production effect of the battery under the condition of low addition amount because the silane additive contains trimethylsilyl groups and acyloxy groups, and has no obvious deterioration on the cycle life and high-temperature storage of the battery.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
electrolyte additive, including silane additive, the structure is as shown in formula (I):
wherein R1, R2, R3 and R4 are independently selected from any one of alkyl, alkynyl, fluoroalkyl, fluoroalkynyl, phenyl and silane.
As a further preference, R1, R2, R3, R4 are independently selected from the group consisting of C1-C6 alkyl, C2-C6 alkynyl, C1-C6 alkylbenzene, C1-C6 alkylsilicon.
As still further preferred, the silane-based additive is at least one of the compounds 1 to 11:
the silane additive disclosed by the invention contains carbonyl and siloxane groups, the carbonyl and the siloxane groups share 1 oxygen atom, and the silane additive is subjected to reduction reaction in preference to other components of the electrolyte, so that a compact and stable SEI film is generated to inhibit the decomposition of the electrolyte; in the formation process, the additive can react with other components in the electrolyte to generate a compact SEI film on the surface of the material, so that the contact between the electrolyte and the material is reduced, the decomposition of the electrolyte is reduced, the gas production is reduced, and the cycle performance is improved. The c=o bond of the carbonyl group in compounds 5 and 6 is adjacent to a carbon-carbon triple bond or a carbon-carbon double bond, creating a conjugation effect, which is more advantageous for the improvement of the above properties.
Preferably, the electrolyte additive further comprises a fluorine-containing lithium salt additive. The fluorine-containing lithium salt additive can improve the long-term high-temperature cycle stability of the battery.
Preferably, the fluorine-containing lithium salt is selected from one or more of lithium bis (trifluoromethylsulfonyl) imide and lithium bis (trifluoromethylsulfonyl) imide. The fluorine-containing lithium salt additive can construct an interfacial film which has stronger ionic conductivity and is beneficial to charge migration, thereby inhibiting the continuous increase of the impedance of a battery core in the battery cycle process and improving the long-term high-temperature cycle stability of the battery.
The silane additive and the fluorine-containing lithium salt additive are matched with each other, so that the power and the low-temperature discharge performance of the battery are improved.
The invention also provides an electrolyte comprising a lithium salt, an organic solvent and the electrolyte additive.
Preferably, the silane additive and the fluorine-containing lithium salt additive account for 0.1 to 15.0 percent of the total mass of the electrolyte.
More preferably, the silane additive and the fluorine-containing lithium salt additive respectively account for 0.1 to 5.0% and 0.2 to 5.0% of the total mass of the electrolyte.
The organic solvent is selected from one or more of common solvents in electrolyte, such as ethylene carbonate, propylene carbonate, butylene carbonate, pentene carbonate, fluoroethylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, 1, 4-butyrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate and ethyl butyrate.
The lithium salt is selected from conventional lithium salts in electrolyte, such as LiPF 6 、LiN(SO 2 F) 2 、LiBF 4 、LiClO 4 、LiAsF 6 、LiB(C 2 O 4 ) 2 、LiBF 2 C 2 O 4 、LiN(SO 2 RF) 2 、LiN(SO 2 F)(SO 2 RF), wherein RF is CnF 2n+1 N=1 to 10; further, n is 1-3, RF is-CF 3 ，-CF 2 CF 3 or-CF 2 CF 2 CF 3 The method comprises the steps of carrying out a first treatment on the surface of the Further, the lithium salt is selected from LiPF 6 、LiN(SO 2 F) 2 、LiB(C 2 O 4 ) 2 、LiBF 2 C 2 O 4 One or more of the following; further, the lithium salt is selected from LiPF 6 、LiN(SO 2 F) 2 、LiBF 2 C 2 O 4 One or more of the following. The lithium salt does not includeThe components of the fluorine-containing lithium salt additive.
Preferably, the molar concentration of the lithium salt in the electrolyte is 0.8 to 1.2mol/L.
The invention also provides a lithium battery, which comprises a positive plate, a negative plate, a diaphragm and the electrolyte.
Preferably, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active slurry layer on the positive electrode current collector, wherein the positive electrode material is selected from LiCoO 2 、LiNiO 2 、LiMn 2 O 4 、LiFePO 4 And LiNi x Co y Mn z O 2 One or more of the following; where x+y+z=1.
Preferably, the negative electrode sheet comprises a negative electrode current collector and a negative electrode active slurry layer positioned on the negative electrode current collector, wherein the negative electrode material is selected from one or more of natural graphite, artificial graphite, a mixture of natural graphite and artificial graphite, lithium carbonate, silicon oxide and silicon carbon composite.
Preferably, the diaphragm comprises a compound mainly composed of one or more of polyethylene, polypropylene, polyimide, aramid, ceramic and PVDF.
Therefore, the invention has the beneficial effects that: (1) The oxidative decomposition of the electrolyte is inhibited by the silane additive, so that the cycling stability of the lithium ion battery at high temperature is improved; (2) The interface impedance between the electrolyte and the positive electrode and the negative electrode is reduced by the fluorine-containing lithium salt additive, and the utilization rate of the active material is improved. The additives in the electrolyte are silane additives and fluorine-containing lithium salt additives, and the high-temperature cycle performance and the high-temperature storage performance of the prepared lithium ion battery are improved greatly.
Detailed Description
The technical scheme of the invention is further described through specific embodiments.
In the present invention, unless otherwise specified, the materials and equipment used are commercially available or are commonly used in the art, and the methods in the examples are conventional in the art unless otherwise specified.
Example 1
The preparation method of the lithium battery comprises the following steps:
(1) Preparing a negative plate: mixing silicon-carbon composite particles serving as a negative electrode active material, styrene-butadiene rubber (SBR) serving as a binder, sodium carboxymethylcellulose (CMC) serving as a thickener, carbon black serving as a conductive agent and a carbon tube according to a mass ratio of 97:1:1, adding deionized water, stirring in a vacuum stirrer until the mixture is stable and uniform to obtain negative electrode slurry, coating the obtained negative electrode slurry on copper foil with the thickness of 8 mu m after the detected viscosity is qualified, drying the copper foil coated with the slurry in a baking oven at the temperature of 100 ℃, and rolling and punching to obtain a negative electrode plate.
(2) Preparation of a positive plate: the positive electrode active material nickel cobalt lithium manganate (LiNi 0.8 Mn 0.1 Co 0.1 ) Mixing polyvinylidene fluoride (PVDF) binder, carbon black as a conductive agent and a carbon tube according to a mass ratio of 97:1:1, adding N-methyl pyrrolidone, stirring in a vacuum stirrer until the mixture is stable and uniform to obtain positive electrode slurry, coating the obtained positive electrode slurry on aluminum foil with the thickness of 12 mu m after the detected viscosity is qualified, drying the aluminum foil coated with the slurry in a baking oven at the temperature of 100 ℃, and rolling and punching to obtain the positive electrode plate.
(3) Preparation of nonaqueous electrolyte: mixing anhydrous solvent ethylene carbonate, methyl ethyl carbonate and diethyl carbonate according to a mass ratio of 1:1:1, adding 12.5% of lithium hexafluorophosphate by mass fraction, uniformly mixing, and then adding an additive, wherein the additive is compound 1 with a mass ratio of 0.5% and lithium difluorosulfimide salt with a mass ratio of 3%.
(4) And (3) assembling a battery cell: and laminating the prepared positive and negative plates and the diaphragm according to the designed capacity, packaging by using an aluminum plastic film to obtain a dry battery cell, and drying in vacuum at 85 ℃.
(5) And (3) liquid injection pre-filling and formation: and (3) injecting the prepared electrolyte into the dry battery cell according to a designed electrolyte injection coefficient in a glove box, sealing, standing at normal temperature, forming, exhausting and sealing secondarily to obtain the activated lithium ion battery.
Performance test method of lithium battery
(1) High temperature cycle test: the battery was charged to 4.25V at a constant current and constant voltage of 1C at 45C, and the off current was 0.05C. Then, the initial discharge capacity D1 was recorded by constant-current discharge at 1C to 2.8V. The test was stopped by cycling until the discharge capacity was less than 80% of the initial capacity.
(2) High temperature storage test: the battery was charged to 4.25V at a constant current and constant voltage of 0.3C, the off-current was 0.05C, and then discharged to 2.8V at a constant current of 0.3C, and the initial discharge capacity D1 was recorded, and was charged again. After the battery was stored at 60 ℃ for N days, the battery was taken out and cooled to room temperature, discharged to 2.8V at a constant current of 0.3C, the discharge capacity Dn was recorded, the battery was fully charged, the charge capacity was recorded as Cn, the capacity retention=dn/D1, and the capacity recovery=cn/D1.
Examples 2-11 and comparative examples 1-5 differ from example 1 only in the electrolyte additives, see table in detail.
Example 12
The difference from example 1 is in the preparation of the nonaqueous electrolyte in step (3): mixing anhydrous solvent ethylene carbonate, methyl ethyl carbonate and ethyl butyrate according to the mass ratio of 1:1:1, adding 12.5% of lithium hexafluorophosphate by mass fraction, uniformly mixing, and then adding an additive, wherein the additive is compound 1 with the mass ratio of 5% and lithium difluorosulfimide salt with the mass ratio of 0.2%.
As can be seen from the above table, the high temperature cycle performance and the high temperature storage performance of the lithium battery of each example of the present invention are improved greatly as compared with the comparative examples. Wherein the c=o bond of the carbonyl group in the silane additives used in examples 5 and 6 is adjacent to a carbon-carbon triple bond or a carbon-carbon double bond, resulting in a conjugation effect with optimal performance. Compared with example 5: comparative examples 3 and 4 only used one of the silane additive or the fluorine-containing lithium salt additive, and the performance was far inferior to that of example 5, indicating that the two additives could be matched with each other to significantly improve the performance; comparative example 5 the silane additive of the present invention was replaced with the common commercially available additive 1, 3-propane sultone, and comparative example 2 replaced the silane additive of the present invention with (trimethylsilyl) acetylene of the prior art, both of which perform less well than example 5, demonstrating the structure of the silane additive of the present invention in which the carbonyl and siloxane groups share 1 oxygen atom.
Specifically, it is found from the data of comparative example 1 that the addition of compound 3 and lithium bis (fluorosulfonyl) imide to the electrolyte has the best effect of improving the high-temperature cycle performance and storage performance of the lithium ion battery. Because the silane additive and the fluorine-containing lithium salt additive form a layer of passivation film on the surface of the negative electrode under the synergistic effect, the solvolysis is effectively inhibited, the volume expansion of the silicon-carbon negative electrode is relieved, the battery impedance is further effectively improved, and the risk of the power performance degradation of the battery is effectively reduced, especially in the battery using high voltage and high nickel/silicon-carbon lithium ions. As can be seen from the data of comparative examples 2 and 3, the silane additives with silicon-oxygen bonds and carbonyl functionality provide certain advantages in the high temperature cycling performance and storage performance of lithium ion batteries over silane additives containing only alkynyl groups.
The present invention is not limited to the above-mentioned embodiments, but is capable of modification and variation in all aspects, including all obvious modifications and equivalents, which can be made by those skilled in the art without departing from the scope of the present invention.
Claims (9)
1. An electrolyte additive is characterized by comprising a silane additive, wherein the structure of the silane additive is shown as a formula (I):
wherein R1, R2, R3 and R4 are independently selected from any one of alkyl, alkynyl, fluoroalkyl, fluoroalkynyl, phenyl and silane.
2. An electrolyte additive according to claim 1 wherein R1, R2, R3, R4 are independently selected from C1-C6 alkyl, C2-C6 alkynyl, C1-C6 alkylbenzene, C1-C6 alkylsilicon.
3. An electrolyte additive according to claim 2, wherein the silane-based additive is at least one of compounds 1 to 11:
4. an electrolyte additive according to claim 1, wherein the electrolyte additive further comprises a fluorine-containing lithium salt additive.
5. An electrolyte additive according to claim 4 wherein the fluorine-containing lithium salt is selected from one or more of lithium bis (trifluoromethylsulfonyl) imide.
6. An electrolyte comprising a lithium salt, an organic solvent and the electrolyte additive of any one of claims 1-5.
7. The electrolyte according to claim 6, wherein the silane additive and the fluorine-containing lithium salt additive in the electrolyte additive are 0.1-15.0% of the total mass of the electrolyte.
8. The electrolyte according to claim 7, wherein the silane additive and the fluorine-containing lithium salt additive respectively account for 0.1-5.0% and 0.2-5.0% of the total mass of the electrolyte.
9. A lithium battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte of any one of claims 6-8.
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