CN117638230A - Electrolyte, secondary battery and electric equipment - Google Patents
Electrolyte, secondary battery and electric equipment Download PDFInfo
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- CN117638230A CN117638230A CN202410039959.XA CN202410039959A CN117638230A CN 117638230 A CN117638230 A CN 117638230A CN 202410039959 A CN202410039959 A CN 202410039959A CN 117638230 A CN117638230 A CN 117638230A
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 38
- 239000000654 additive Substances 0.000 claims abstract description 38
- 230000000996 additive effect Effects 0.000 claims abstract description 35
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims abstract description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 6
- 150000001875 compounds Chemical class 0.000 claims abstract description 6
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 4
- 239000010703 silicon Substances 0.000 claims abstract description 4
- 229910003002 lithium salt Inorganic materials 0.000 claims description 11
- 159000000002 lithium salts Chemical class 0.000 claims description 11
- -1 hydroxy, amino Chemical group 0.000 claims description 10
- 239000002210 silicon-based material Substances 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 239000007773 negative electrode material Substances 0.000 claims description 7
- 239000003960 organic solvent Substances 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 4
- 239000007774 positive electrode material Substances 0.000 claims description 4
- 239000002153 silicon-carbon composite material Substances 0.000 claims description 4
- 125000000008 (C1-C10) alkyl group Chemical group 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
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 2
- 150000001335 aliphatic alkanes Chemical group 0.000 claims description 2
- 125000003277 amino group Chemical group 0.000 claims description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 2
- 239000007770 graphite material Substances 0.000 claims description 2
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 claims description 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims description 2
- 125000006318 tert-butyl amino group Chemical group [H]N(*)C(C([H])([H])[H])(C([H])([H])[H])C([H])([H])[H] 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 238000007086 side reaction Methods 0.000 abstract description 6
- 229910018091 Li 2 S Inorganic materials 0.000 abstract description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 5
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 5
- 125000000472 sulfonyl group Chemical group *S(*)(=O)=O 0.000 abstract description 5
- 239000010406 cathode material Substances 0.000 abstract description 3
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 abstract description 2
- 239000000463 material Substances 0.000 abstract description 2
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 12
- 238000003860 storage Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 description 8
- 239000002904 solvent Substances 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 6
- 239000010410 layer Substances 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 5
- 229910052744 lithium Inorganic materials 0.000 description 5
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 4
- HNAGHMKIPMKKBB-UHFFFAOYSA-N 1-benzylpyrrolidine-3-carboxamide Chemical compound C1C(C(=O)N)CCN1CC1=CC=CC=C1 HNAGHMKIPMKKBB-UHFFFAOYSA-N 0.000 description 4
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 description 4
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 4
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 4
- JGFBQFKZKSSODQ-UHFFFAOYSA-N Isothiocyanatocyclopropane Chemical compound S=C=NC1CC1 JGFBQFKZKSSODQ-UHFFFAOYSA-N 0.000 description 4
- RJUFJBKOKNCXHH-UHFFFAOYSA-N Methyl propionate Chemical compound CCC(=O)OC RJUFJBKOKNCXHH-UHFFFAOYSA-N 0.000 description 4
- OBNCKNCVKJNDBV-UHFFFAOYSA-N butanoic acid ethyl ester Natural products CCCC(=O)OCC OBNCKNCVKJNDBV-UHFFFAOYSA-N 0.000 description 4
- PWLNAUNEAKQYLH-UHFFFAOYSA-N butyric acid octyl ester Natural products CCCCCCCCOC(=O)CCC PWLNAUNEAKQYLH-UHFFFAOYSA-N 0.000 description 4
- ROORDVPLFPIABK-UHFFFAOYSA-N diphenyl carbonate Chemical compound C=1C=CC=CC=1OC(=O)OC1=CC=CC=C1 ROORDVPLFPIABK-UHFFFAOYSA-N 0.000 description 4
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 4
- 229940017219 methyl propionate Drugs 0.000 description 4
- KKQAVHGECIBFRQ-UHFFFAOYSA-N methyl propyl carbonate Chemical compound CCCOC(=O)OC KKQAVHGECIBFRQ-UHFFFAOYSA-N 0.000 description 4
- YKYONYBAUNKHLG-UHFFFAOYSA-N n-Propyl acetate Natural products CCCOC(C)=O YKYONYBAUNKHLG-UHFFFAOYSA-N 0.000 description 4
- UUIQMZJEGPQKFD-UHFFFAOYSA-N n-butyric acid methyl ester Natural products CCCC(=O)OC UUIQMZJEGPQKFD-UHFFFAOYSA-N 0.000 description 4
- 229940090181 propyl acetate Drugs 0.000 description 4
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 4
- NQPDZGIKBAWPEJ-UHFFFAOYSA-N valeric acid Chemical compound CCCCC(O)=O NQPDZGIKBAWPEJ-UHFFFAOYSA-N 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical group O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
- 239000002033 PVDF binder Substances 0.000 description 3
- 229920002125 Sokalan® Polymers 0.000 description 3
- 239000002174 Styrene-butadiene Substances 0.000 description 3
- 229910021383 artificial graphite Inorganic materials 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 229920003048 styrene butadiene rubber Polymers 0.000 description 3
- 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 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 2
- 238000010494 dissociation reaction Methods 0.000 description 2
- 230000005593 dissociations Effects 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 description 2
- 229910001486 lithium perchlorate Inorganic materials 0.000 description 2
- 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 description 2
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 239000011268 mixed slurry Substances 0.000 description 2
- 239000012046 mixed solvent Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 239000002985 plastic film Substances 0.000 description 2
- 229920006255 plastic film Polymers 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910004437 Li(Ni0.8Mn0.1Co0.1)O2 Inorganic materials 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000007547 defect Effects 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
- 230000000694 effects Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000007731 hot pressing Methods 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
- 239000004816 latex Substances 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- XKLXIRVJABJBLQ-UHFFFAOYSA-N lithium;2-(trifluoromethyl)-1h-imidazole-4,5-dicarbonitrile Chemical compound [Li].FC(F)(F)C1=NC(C#N)=C(C#N)N1 XKLXIRVJABJBLQ-UHFFFAOYSA-N 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 239000011356 non-aqueous organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 125000006340 pentafluoro ethyl group Chemical group FC(F)(F)C(F)(F)* 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- PBIMIGNDTBRRPI-UHFFFAOYSA-N trifluoro borate Chemical compound FOB(OF)OF PBIMIGNDTBRRPI-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The application belongs to the technical field of secondary batteries, and particularly relates to electrolyte, a secondary battery and electric equipment. The electrolyte provided by the application comprises a compound with a structure shown in a formula I, wherein the compound contains sulfonyl and borate at the same time, so that the sulfide content (such as Li 2 S、ROSO 2 Li、Li 2 S x O y Etc.), the conductivity of lithium ions at the interface can be improved, thereby reducing the impedance and improving the dynamic performance of the battery. Meanwhile, the side reaction of the anode/electrolyte interface can be inhibited, and the gas production risk of the battery is reduced. In addition, the elastic modulus and mechanical properties of the interface layer (CEI and SEI) are obviously enhanced compared with those of the interface layer without the additive, and the interface layer and the living property can be improvedThe structural stability of the material can inhibit the side reaction of the interface and relieve the volume expansion of the cathode material, especially the silicon cathode material.
Description
Technical Field
The application belongs to the technical field of secondary batteries, and particularly relates to electrolyte, a secondary battery and electric equipment.
Background
The secondary battery has the advantages of high specific energy, small volume, light weight, short charging time, no memory effect and the like, and plays an important role in the energy storage field. However, with the development of society, the consumer market has put higher demands on the performance of secondary batteries, so that the development of a battery having high cycle performance and safety performance is an urgent need for the current development of the battery industry.
The electrolyte is a component in contact with all parts in the battery, and can effectively regulate and control the physical and chemical characteristics of the electrolyte to various properties including interface structure and stability by perfecting the design of the electrolyte, thereby improving the cycle performance and the safety performance of the battery.
Disclosure of Invention
Therefore, the technical problem to be solved by the application is to overcome the defect that the existing secondary battery has poor cycle performance and safety performance, so as to provide electrolyte, the secondary battery and electric equipment.
Therefore, the application provides the following technical scheme:
the application provides an electrolyte comprising a lithium salt, an organic solvent, and a first additive comprising a compound having a structure represented by formula I:
wherein,ortho, meta and para positions of the borate; r in the additive 1 At least one of C1-C10 alkyl, hydroxy, amino and C1-C10 amino; r is R 2 Comprises at least one of H and methyl.
Optionally, the C1-C10 alkane group comprises at least one of methyl, ethyl and isopropyl;
and/or the amino group of C1-C10 contains at least one of N, N-dimethylamino and tert-butylamino.
Optionally, the first additive includes a structure as shown in any one of the following:
the first additive provided by the invention has sulfonyl and borate. On the one hand, the sulfonyl group contains an S element, and the SEI is formed by the sulfonyl group and Li in CEI 2 S x 、ROSO 2 Li、Li 2 S x O y The S-containing derivatives are favorable for the conduction of lithium ions in the interface and can be changedGood electrochemical reaction kinetics; in addition, the S component can promote mechanical performance of the interface and improve stability of the interface. The 2p empty orbit on the B element in the borate can be combined with singlet oxygen to annihilate the side reaction catalytic activity of the singlet oxygen, so that the side reaction of the electrolyte and the singlet oxygen at the interface is inhibited, the stability of the interface is improved, and the gas production risk of the battery can be reduced. The two are cooperated to improve the cycle performance and the safety performance of the battery.
Optionally, the first additive accounts for 0.1 to 5.0 percent of the total mass of the electrolyte. For example, the mass ratio of the first additive may be one or any range value between 0.1%, 0.5%, 1.0%, 2%, 3.0%, 5.0%.
When the mass ratio of the first additive is maintained within the range of 0.1-5.0%, the passivation layer formed at the electrode/electrolyte interface is uniform and compact, so that the electronic conduction can be effectively blocked, and the electrolyte is inhibited from further reacting at the interface; meanwhile, the lithium ions are promoted to be transmitted in the interface layer, and the interface impedance is reduced. The interface protection layer formed by the content range has high mechanical strength, and can inhibit structural collapse in the lithium intercalation and deintercalation process of the anode electrode material and the cathode electrode material, thereby improving the cycle life of the battery.
Optionally, a second additive is also included, the second additive comprising at least one of a fluorocarbonate, a vinylene carbonate.
In the application, the second additive is a typical negative electrode film forming additive, so that the stability of a negative electrode/electrolyte interface can be effectively improved, the first additive and the second additive are matched for use, the first additive and the second additive can better act on a positive electrode interface and a negative electrode interface at the same time, and the combination of the first additive and the second additive can further give consideration to the performance of a full battery.
Optionally, the mass ratio of the first additive to the second additive is (1-10): (1-15).
For example, the mass ratio of the first additive to the second additive may be a range of values between one or any two of 1:15, 1:5, 1:2, 5:2, 10:1.
Optionally, the lithium salt accounts for 10.0% -20% of the total mass of the electrolyte.
For example, the lithium salt mass may be in a range of values between one or any two of 10%, 12%, 13%, 14%, 15%, 16%, 18%, 20% of the total mass of the electrolyte.
In this application, the lithium salts used are conventional in the art. Typically, but not by way of limitation, the lithium salt is lithium hexafluorophosphate (LiPF 6 ) One or more of the following lithium salts may also be included: lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (oxalato) borate (LiBOB), lithium difluorooxalato borate (LiDFOB), lithium difluorodioxaato phosphate (LiDFOP), lithium bis (fluorosulfonyl) imide (LiLSI) and lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium perchlorate (LiClO) 4 ) Lithium difluorophosphate (LiPO) 2 F 2 ) Lithium pentafluoroethyl trifluoroborate (LiDAB), lithium 2-trifluoromethyl-4, 5-dicyanoimidazole (LiTDI). The lithium hexafluorophosphate has moderate ion migration number, moderate dissociation constant, good oxidation resistance and good aluminum foil passivation capability in a common nonaqueous organic solvent, can be matched with various anode and cathode materials, and is one of the most main lithium salts in the secondary battery. Compared with lithium hexafluorophosphate, the lithium bis (fluorosulfonyl) imide has higher ion migration number and greater dissociation degree, is favorable for improving the ion conductivity, but can be mixed with lithium hexafluorophosphate as a main salt in consideration of the corrosiveness of the lithium bis (fluorosulfonyl) imide to an aluminum current collector.
In the present application, the selection of the organic solvent is also conventional in the art, and typically, but not limited to, the organic solvent includes a first solvent and a second solvent, where the negative electrode material is graphite, the first solvent is ethylene carbonate, and the second solvent is at least one selected from Propylene Carbonate (PC), butylene Carbonate (BC), fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), methylpropyl carbonate (MPC), diphenyl carbonate (DPhC), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), and γ -butyrolactone (γ -GBL); when the negative electrode material is a silicon-based material, the first solvent is fluoroethylene carbonate (FEC), and the second solvent includes at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), butylene Carbonate (BC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), methylpropyl carbonate (MPC), diphenyl carbonate (DPhC), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), and γ -butyrolactone (γ -GBL).
The application also provides a secondary battery, which comprises a positive electrode plate, a negative electrode plate, a diaphragm and the electrolyte.
Optionally, the positive electrode sheet comprises a positive electrode active material, and the chemical formula of the positive electrode active material comprises Li a Ni x Co y Mn z M b O 2 Wherein a is more than or equal to 0.95 and less than or equal to 1.2,0.5, x is more than or equal to 1.0, y is more than or equal to 0 and less than or equal to 0.3, z is more than or equal to 0 and less than or equal to 0.2, and b is more than or equal to 0 and less than or equal to 0<0.1, and x+y+z+b=1.0, m includes at least one of Al, zr, ti, V, mg, fe, B, mo;
and/or the negative electrode plate comprises a negative electrode active material, wherein the negative electrode active material comprises at least one of a graphite material and a silicon-based material, and the silicon-based material comprises at least one of a simple substance silicon, a silicon-carbon composite material, a silicon-oxygen compound or a silicon metal compound, and the mass of the silicon-carbon composite material in the silicon-based material accounts for 3-30% of the mass of the silicon-based material.
The application also provides electric equipment, which comprises the secondary battery.
Other compositions and preparation methods of the secondary battery and the electric equipment provided by the application are conventional in the field, and are not particularly limited herein.
The technical scheme of the application has the following advantages:
the electrolyte provided by the application comprises a compound with a structure shown in a formula I, wherein the compound contains sulfonyl and borate at the same time, so that the sulfide content (such as Li 2 S、ROSO 2 Li、Li 2 S x O y Etc.), the conductivity of lithium ions at the interface can be improved, thereby reducing the impedance and improving the dynamic performance of the battery. Meanwhile, the side reaction of the anode/electrolyte interface can be inhibited, and the gas production risk of the battery is reduced. This isIn addition, the elastic modulus and the mechanical property of the interface layer (CEI and SEI) are obviously enhanced compared with those of the interface layer without the additive, the structural stability of the interface layer and the active material can be improved, the side reaction of the interface is inhibited, and the volume expansion of the anode material (especially the silicon anode) is relieved.
Detailed Description
The following examples are provided for a better understanding of the present application and are not limited to the preferred embodiments described, but are not intended to limit the scope of the present application, and any product that is the same or similar to the present application, given the benefit of this disclosure or the combination of this application with other prior art features, falls within the scope of this application.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
Example 1
The application provides a secondary battery, which comprises the following specific components and preparation methods:
the specific composition of the electrolyte is shown in table 1, and the preparation steps are as follows:
(1) Mixing the organic solvents to obtain a mixed solvent, and then usingRemoving water by using a molecular sieve for standby;
(2) Sequentially adding lithium salt into the mixed solvent obtained in the step (1) in a glove box filled with argon at room temperature, continuously stirring and cooling to obtain colorless transparent liquid; (3) And (3) adding an additive into the colorless transparent liquid obtained in the step (2) to obtain the electrolyte.
Preparation of positive electrode plate
Positive electrode active material Li (Ni 0.8 Mn 0.1 Co 0.1 )O 2 (NMC 811), acetylene black (Super P) as a conductive agent and polyvinylidene fluoride (PVDF, molecular weight 110 ten thousand) as a binder in mass ratio NMC811 Super P: PVDF=94:3:3, uniformly mixing, uniformly dispersing with 1-methyl-2-pyrrolidone (NMP) to prepare uniform black slurry, coating the mixed slurry on two sides of an aluminum foil, baking, rolling and cutting to obtain positive pole pieces, wherein the compacted density of the positive pole pieces is 3.5g/cm 3 。
Preparation of negative electrode plate
Uniformly mixing negative electrode active material Artificial Graphite (AG), conductive agent acetylene black (Super P), polyacrylic acid (PAA, chengduyule, LA 136D) and Binder styrene-butadiene latex (SBR, BASF, binder 21-11) according to the mass ratio AG: super P: PAA: SBR=94:3:2:1, uniformly dispersing into deionized water to prepare uniform black slurry, coating the mixed slurry on two sides of a copper foil, baking, rolling, cutting to obtain a negative electrode plate, wherein the compaction density of the obtained negative electrode plate is 1.6g/cm 3 。
Manufacture of soft package battery
The prepared positive plate and diaphragm (star source material, 9 μm PE)&3μm Al 2 O 3 Coating layer) and negative electrode sheets are sequentially stacked, the diaphragm is positioned between the positive electrode sheet and the negative electrode sheet, the bare cell is obtained through winding, hot-pressing shaping and tab welding, the bare cell is placed in an outer package aluminum plastic film, the outer package aluminum plastic film is placed in an oven at 85+/-10 ℃ for baking for 24 hours, the prepared electrolyte is injected into a dried battery, and standing, formation and capacity division are carried out, so that the preparation of the lithium ion soft package battery is completed.
Examples 2 to 17
Examples 2 to 17 were similar to example 1 except that the electrolyte component contents were set as shown in table 1.
Comparative examples 1 to 4
Comparative examples 1 to 4 were the same as example 1 except that the electrolyte component contents were set as shown in table 1.
Battery performance test
Normal temperature DCR test: at 25±2 ℃, the soft pack battery 1C obtained in examples and comparative examples was charged to 4.25V, discharged at 1C capacity for 30min, and after being adjusted to 50% soc, 5C constant current pulse discharge was performed for 10s and then charged for 10s, and dcr= (voltage before pulse discharge-voltage after pulse discharge)/discharge current was calculated. After storage at 60 ℃ for 30 days, when the battery was completely cooled to 25±2 ℃, DCR was again tested, and the internal resistance change rate after storage = (DCR after 30 days-DCR before 30 days)/DCR before 30 days was 100%, and the obtained recording results are shown in table 2.
And (3) testing normal temperature cycle performance: the soft pack batteries obtained in examples and comparative examples were subjected to charge-discharge cycle test at 25.+ -. 2 ℃ at a charge-discharge rate of 1C/1C in the range of 2.8 to 4.25V, and the first-week discharge specific capacity and the discharge specific capacity after 1000-week cycle of the batteries were recorded. Capacity retention for 1000 weeks = specific discharge capacity for 1000 weeks/specific discharge capacity for first week x 100%, recorded data are shown in table 2.
High temperature storage performance: the soft pack batteries obtained in examples and comparative examples were subjected to charge and discharge tests at 60.+ -. 2 ℃ at a charge and discharge rate of 1C/1C in the range of 2.8 to 4.25V, and the first-week discharge specific capacity of the batteries was recorded, and then stored at 60.+ -. 2 ℃ for 30 days, and again subjected to the charge and discharge tests, and the discharge specific capacity was recorded. High-temperature storage capacity retention = specific discharge capacity after 30 days/specific discharge capacity at first week x 100%, and the recorded data are shown in table 2.
High temperature gas production test: the soft package batteries obtained in the examples and the comparative examples were charged to 4.25V at a constant current of 1C rate at 25±2 ℃ and then charged to a constant voltage of 4.25V to a current of less than 0.05C, so that they were in a full charge state of 4.25V. The volume of the full-charged battery before storage was tested and recorded as V 0 The method comprises the steps of carrying out a first treatment on the surface of the Then the battery in full charge state is placed in an oven at 70+/-2 ℃, after 10 days, the battery is taken out, and the stored volume is immediately tested and recorded as V 1 . Volume expansion ratio= (V 1 -V 0 )/V 0 100% and the results are shown in Table 2.
Table 1 electrolyte formulation
Table 2 test results
As can be seen from the experimental results of the comparative examples and comparative examples, the first additive having a specific structure provided herein can effectively improve the cycle life, storage performance, and reduce the risk of gas production safety of the high-voltage battery, and the improvement effect of the A1, A5, and A8 additives at a content of 1.0wt% is most remarkable. However, as the content of the A1, A5 and A8 additives increases, the initial DCR as well as the DCR change rate of the battery gradually increase. In view of this, the combined electrochemical properties of the A1, A5 and A8 additives at a level of 1.0 wt.% are optimal. Example 14 shows that the second additive VC slightly increases DCR and high temperature storage gas production, but effectively improves cycle performance and storage performance, and in combination with other examples, the first additive and the second additive are combined to achieve superior electrochemical performance and safety performance. Example 15 compared with example 13, liFSI was used as the main salt with LiPF 6 The mixed use and the increase of the total concentration of lithium salt can effectively reduce DCR, improve the cycle performance and the high-temperature storage performance, and only slightly worsen the high-temperature storage gas production. As is clear from the comparison between example 16 and example 15, increasing the ratio of low viscosity solvent (EMC) in the electrolyte is effective in improving DCR, but increases the risk of high temperature gassing.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present application.
Claims (10)
1. An electrolyte comprising a lithium salt, an organic solvent, and a first additive comprising a compound having the structure of formula I:
wherein,ortho, meta and para positions of the borate; r in the additive 1 At least one of C1-C10 alkyl, hydroxy, amino and C1-C10 amino; r is R 2 Comprises at least one of H and methyl.
2. The electrolyte according to claim 1, wherein the C1-C10 alkane group comprises at least one of methyl, ethyl, isopropyl;
and/or the amino group of C1-C10 contains at least one of N, N-dimethylamino and tert-butylamino.
3. The electrolyte of claim 2 wherein the first additive comprises any one of the following structures:
4. the electrolyte according to any one of claims 1 to 3, wherein the first additive is present in an amount of 0.1 to 5.0% by mass based on the total mass of the electrolyte.
5. The electrolyte of claim 1, further comprising a second additive comprising at least one of a fluorocarbonate, a vinylene carbonate.
6. The electrolyte according to claim 5, wherein the mass ratio of the first additive to the second additive is (1 to 10): (1-15).
7. The electrolyte according to any one of claims 1 to 3, wherein the lithium salt accounts for 10.0 to 20% of the total mass of the electrolyte.
8. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte according to any one of claims 1 to 7.
9. The secondary battery according to claim 8, wherein the positive electrode sheet includes a positive electrode active material having a chemical formula including Li a Ni x Co y Mn z M b O 2 Wherein a is more than or equal to 0.95 and less than or equal to 1.2,0.5, x is more than or equal to 1.0, y is more than or equal to 0 and less than or equal to 0.3, z is more than or equal to 0 and less than or equal to 0.2, and b is more than or equal to 0 and less than or equal to 0<0.1, and x+y+z+b=1.0, m includes at least one of Al, zr, ti, V, mg, fe, B, mo;
and/or the negative electrode plate comprises a negative electrode active material, wherein the negative electrode active material comprises at least one of a graphite material and a silicon-based material, and the silicon-based material comprises at least one of a simple substance silicon, a silicon-carbon composite material, a silicon-oxygen compound or a silicon metal compound, and the mass of the silicon-carbon composite material in the silicon-based material accounts for 3-30% of the mass of the silicon-based material.
10. An electric device comprising the secondary battery according to any one of claims 8 to 9.
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