CN117810532A - Ternary high-voltage lithium ion battery nonaqueous electrolyte and lithium ion battery - Google Patents
Ternary high-voltage lithium ion battery nonaqueous electrolyte and lithium ion battery Download PDFInfo
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- CN117810532A CN117810532A CN202211165530.2A CN202211165530A CN117810532A CN 117810532 A CN117810532 A CN 117810532A CN 202211165530 A CN202211165530 A CN 202211165530A CN 117810532 A CN117810532 A CN 117810532A
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 46
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 46
- 239000011255 nonaqueous electrolyte Substances 0.000 title claims abstract description 23
- 239000000654 additive Substances 0.000 claims abstract description 53
- 239000003792 electrolyte Substances 0.000 claims abstract description 51
- 230000000996 additive effect Effects 0.000 claims abstract description 44
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical group OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 16
- 125000000472 sulfonyl group Chemical group *S(*)(=O)=O 0.000 claims abstract description 14
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 12
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 12
- 150000001875 compounds Chemical class 0.000 claims abstract description 7
- 239000011356 non-aqueous organic solvent Substances 0.000 claims abstract description 5
- 239000012948 isocyanate Substances 0.000 claims description 22
- -1 isocyanate compound Chemical class 0.000 claims description 21
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 13
- 229910052744 lithium Inorganic materials 0.000 claims description 13
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 11
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims description 11
- 229910000077 silane Inorganic materials 0.000 claims description 11
- ZPFAVCIQZKRBGF-UHFFFAOYSA-N 1,3,2-dioxathiolane 2,2-dioxide Chemical compound O=S1(=O)OCCO1 ZPFAVCIQZKRBGF-UHFFFAOYSA-N 0.000 claims description 9
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 9
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 8
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 8
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 8
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 8
- YZYKZHPNRDIPFA-UHFFFAOYSA-N tris(trimethylsilyl) borate Chemical compound C[Si](C)(C)OB(O[Si](C)(C)C)O[Si](C)(C)C YZYKZHPNRDIPFA-UHFFFAOYSA-N 0.000 claims description 6
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 4
- 229910019142 PO4 Inorganic materials 0.000 claims description 4
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 claims 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 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 4
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000010452 phosphate Substances 0.000 claims description 4
- QJMMCGKXBZVAEI-UHFFFAOYSA-N tris(trimethylsilyl) phosphate Chemical compound C[Si](C)(C)OP(=O)(O[Si](C)(C)C)O[Si](C)(C)C QJMMCGKXBZVAEI-UHFFFAOYSA-N 0.000 claims description 4
- VMZOBROUFBEGAR-UHFFFAOYSA-N tris(trimethylsilyl) phosphite Chemical compound C[Si](C)(C)OP(O[Si](C)(C)C)O[Si](C)(C)C VMZOBROUFBEGAR-UHFFFAOYSA-N 0.000 claims description 4
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 3
- 125000001424 substituent group Chemical group 0.000 claims description 3
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 2
- 229910013075 LiBF Inorganic materials 0.000 claims description 2
- 229910013872 LiPF Inorganic materials 0.000 claims description 2
- 101150058243 Lipf gene Proteins 0.000 claims description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 2
- 239000011149 active material Substances 0.000 claims description 2
- 125000000217 alkyl group Chemical group 0.000 claims description 2
- 125000001153 fluoro group Chemical group F* 0.000 claims description 2
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 claims description 2
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 2
- 229910021382 natural graphite Inorganic materials 0.000 claims description 2
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims description 2
- 229910052710 silicon Inorganic materials 0.000 claims description 2
- 239000010703 silicon Substances 0.000 claims description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims 2
- 238000003860 storage Methods 0.000 abstract description 10
- 230000009471 action Effects 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 10
- 238000000034 method Methods 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 150000002513 isocyanates Chemical class 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910002804 graphite Inorganic materials 0.000 description 5
- 239000010439 graphite Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 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
- 239000006230 acetylene black Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- WVQUCYVTZWVNLV-UHFFFAOYSA-N boric acid;oxalic acid Chemical compound OB(O)O.OC(=O)C(O)=O WVQUCYVTZWVNLV-UHFFFAOYSA-N 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000012044 organic layer Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000009517 secondary packaging Methods 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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Abstract
The invention belongs to the technical field of lithium ion batteries, and discloses a ternary high-voltage lithium ion battery nonaqueous electrolyte and a lithium ion battery. The ternary high-voltage lithium ion battery nonaqueous electrolyte comprises a nonaqueous organic solvent, electrolyte lithium salt, a film-forming additive, an oxalate-type additive and a silane-type additive, wherein the electrolyte lithium salt is not oxalate, and the film-forming additive comprises isocyanate-type compounds containing sulfonyl structures. According to the nonaqueous electrolyte, through optimizing the formula, under the combined action of multiple components in a unique combination, the electrolyte system has high energy density and high stability, so that the requirements of the electrolyte on circulation and storage performance under high voltage are met, and meanwhile, the safety is ensured.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a ternary high-voltage lithium ion battery nonaqueous electrolyte and a lithium ion battery.
Background
With technological progress, the quality requirements of people on living environments are continuously improved, and the environmental pollution problems caused by the increasingly depleted and consumed fossil energy sources are more serious, so that the research and development of clean renewable new energy sources become urgent. A large amount of new energy sources such as solar energy, wind energy, tidal energy, geothermal energy and the like are developed and used at present, but the energy sources are limited in time and space and need to be properly converted and stored for use.
The lithium ion battery is used as a green environment-friendly high-energy battery and is the most ideal and potential rechargeable battery in the world at present. Compared with other batteries, the battery has a series of advantages of no memory effect, rapid charge and discharge, high energy density, long cycle life, no environmental pollution and the like, and is widely applied to small electronic equipment such as notebook computers, video cameras, mobile phones, electronic watches and the like. However, with the continuous increase of the capacity requirements of lithium ion batteries, such as pure electric vehicles, hybrid electric vehicles, portable energy storage devices, and the like, it is expected to develop lithium ion batteries with higher energy density and power density to realize long-term endurance and energy storage.
The energy density of the lithium ion battery can be improved by improving the working voltage, but the electrochemical window of the traditional carbonate electrolyte is narrower, and after the voltage is increased, the electrolyte can be decomposed on one hand; on the other hand, the oxidation capability of the anode under high pressure is enhanced, a large amount of metal is dissolved, gas is separated out, and the phase change of the material causes the battery to fail and even causes safety accidents. The above problems limit the development of high-voltage lithium ion batteries, and therefore, development of high-performance and high-safety electrolytes resistant to high voltages is required.
Disclosure of Invention
The invention aims to overcome the defects of the background technology and provide a ternary high-voltage lithium ion battery nonaqueous electrolyte and a lithium ion battery. According to the ternary high-voltage lithium ion battery nonaqueous electrolyte, through optimizing a formula, under the combined action of multiple components of a unique combination, an electrolyte system has high energy density and high stability, so that the requirements of the electrolyte on circulation and storage performance under high voltage are met, and meanwhile, the safety is ensured.
In order to achieve the purpose of the invention, the nonaqueous electrolyte of the ternary high-voltage lithium ion battery comprises a nonaqueous organic solvent, an electrolyte lithium salt, a film forming additive, an oxalate additive and a silane additive, wherein the electrolyte lithium salt is not of an oxalate type, the film forming additive comprises an isocyanate compound containing a sulfonyl structure, and the structural formula of the isocyanate compound is shown as the formula (I):
wherein the substituents R 1 、R 2 Independently selected from the group consisting of alkyl groups of 1-4 carbons, phenyl groups, fluoro groups, isocyanate groups.
Further, in some embodiments of the present invention, the isocyanate-based compound is selected from at least one of the compounds represented by the following structural formulas:
preferably, in some embodiments of the present invention, the isocyanate-based compound is 0.15 to 1.1% by mass in the electrolyte.
Further, in some embodiments of the present invention, the film-forming additive comprises at least one of 1, 3-Propane Sultone (PS), fluoroethylene carbonate (FEC), vinylene Carbonate (VC), and ethylene sulfate (DTD); preferably, in some embodiments of the present invention, the film forming additive is present in the electrolyte in an amount of 0.5 to 5% by mass.
Further, in some embodiments of the invention, the oxalate-based additive is selected from one or more of lithium difluorobis-oxalato-phosphate (LiDFOP), lithium difluorooxalato-borate (LiDFOB), lithium tetrafluorooxalato-phosphate (LTFOP), and lithium bis-oxalato-borate (LiBOB); preferably, in some embodiments of the present invention, the oxalate-based additive is present in the electrolyte at a mass percentage of 0.3-1.5%.
Further, in some embodiments of the invention, the silane-based additive is selected from one or more of tris (trimethylsilyl) phosphate (TMSP), tris (trimethylsilyl) borate (TMSB), tris (trimethylsilyl) phosphite (TMSPi); preferably, in some embodiments of the present invention, the silane-based additive is 0.1-2% by mass of the electrolyte.
Preferably, in some embodiments of the present invention, the film forming additive is Vinylene Carbonate (VC) or ethylene sulfate (DTD), and the silane-based additive is tris (trimethylsilyl) phosphate (TMSP) or tris (trimethylsilyl) borate (TMSB); wherein the mass percentage of the film forming additive in the electrolyte is 0.3-0.7%, and the mass percentage of the silane additive in the electrolyte is 0.3-1.2%.
Further preferably, in some embodiments of the present invention, when the film-forming additive is ethylene sulfate (DTD), the oxalate-type additive does not contain lithium bis (oxalato) borate (LiBOB).
Further, in some embodiments of the invention, the electrolyte lithium salt is selected from lithium hexafluorophosphate (LiPF 6 ) Lithium bis (fluorosulfonyl) imide (LiLSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium difluorophosphate (LiPO) 2 F 2 ) Lithium tetrafluoroborate (LiBF) 4 ) One or more of the following.
Preferably, in some embodiments of the present invention, the mass percentage of the electrolyte lithium salt in the electrolyte is 10 to 20%.
Further, in some embodiments of the invention, the non-aqueous organic solvent is selected from one or more of Ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC), ethyl Methyl Carbonate (EMC).
On the other hand, the invention also provides a ternary high-voltage lithium ion battery, which comprises a positive electrode, a negative electrode, a diaphragm and the ternary high-voltage lithium ion battery nonaqueous electrolyte.
Further, in some embodiments of the invention, the active material of the positive electrode is a ternary NCM material; the negative electrode is made of one or more of natural graphite, artificial graphite, lithium titanate, silicon-oxygen negative electrode and silicon negative electrode.
Further, in some embodiments of the invention, the upper cutoff voltage of the high voltage is 4.35-4.5V.
Compared with the prior art, the invention has the advantages that:
(1) In the nonaqueous electrolyte of the high-voltage lithium ion battery, functional groups (fluorosulfonyl structure can improve the content of S element in SEI film, reduce interface resistance and accelerate kinetics of lithium ion movement) contained in isocyanate compound with specific structural formula form SEI film with multiple inorganic components, thinner organic layer and low impedance on the negative electrode, so as to improve the multiplying power capability of the battery; the high-voltage environment is adapted, a stable CEI film is formed at the positive electrode, the water-acid environment is optimized, the impedance increase in the circulation and storage processes is restrained, the storage performance of the battery is improved, the internal resistance increase and gas production in the use process are reduced, and the circulation stability and the thermal stability of the battery are comprehensively ensured.
(2) According to the nonaqueous electrolyte for the high-voltage lithium ion battery, through optimizing a formula and combining the combined action of isocyanate compounds containing sulfonyl structures, oxalate additives and silicate-containing borate additives in a specific structural formula, the nonaqueous electrolyte for the high-voltage lithium ion battery comprises a main component and a main component, wherein the main component is a main component of a lithium ion battery, and the main component is a main component of the main component: the positive and negative electrodes of the isocyanate additive containing sulfonyl structure form a film, and inhibit gas production, and inhibit impedance increase in the circulating and storing processes; the oxalate additive plays a film forming role, and simultaneously optimizes the film impedance through the isocyanate additive containing sulfonyl structure, and inhibits the gas production side effect of the oxalate additive; oxidation stability of EC and Li enhancement by silicate-containing borate additives + The migration number, and further comprehensively ensures that the high-voltage lithium ion battery has excellent cycle performance and storage performance, so that the battery system has high energy density and high stability.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that the following description is intended to be illustrative of the invention and not restrictive.
The terms "comprising," "including," "having," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.
When an equivalent, concentration, or other value or parameter is expressed as a range, preferred range, or a range bounded by a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when ranges of "1 to 5" are disclosed, the described ranges should be construed to include ranges of "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a numerical range is described herein, unless otherwise indicated, the range is intended to include its endpoints and all integers and fractions within the range.
The singular forms include plural referents unless the context clearly dictates otherwise. "optional" or "any" means that the subsequently described event or event may or may not occur, and that the description includes both cases where the event occurs and cases where the event does not.
The indefinite articles "a" and "an" preceding an element or component of the invention are not limited to the requirement (i.e. the number of occurrences) of the element or component. Thus, the use of "a" or "an" should be interpreted as including one or at least one, and the singular reference of an element or component includes the plural reference unless the amount clearly dictates otherwise.
Furthermore, the descriptions of the terms "one embodiment," "some embodiments," "examples," "particular examples," or "some examples," etc., described below mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily for the same embodiment or example. The technical features of the respective embodiments of the present invention may be combined with each other as long as they do not collide with each other.
The structures of the sulfonyl structure-containing isocyanate-based compounds in the examples and comparative examples of the present invention are as follows:
the structural formula of M1 is:
the structural formula of M2 is:
the structural formula of M3 is:
the structural formula of M4 is:
m5 has the structural formula:
example 1
Preparation of electrolyte: in a glove box filled with argon gas (oxygen content: 1ppm, water content: 1 ppm), ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC) were mixed in an amount of 25:10:20:45 to obtain a mixed solution, and adding 12.5% lithium hexafluorophosphate (LiPF) based on the total mass of the electrolyte 6 ) 0.5% of lithium difluorooxalato borate (LiDFOB), and then 0.5% of an isocyanate compound M1 containing a sulfonyl structure based on the total mass of the electrolyte, 0.5% of ethylene carbonate (VC) based on the total mass of the electrolyte, andthe electrolyte of example 1 was obtained by stirring tris (trimethylsilyl) borate (TMSB) in an amount of 0.5% by weight based on the total mass of the electrolyte and completely dissolving the tris (trimethylsilyl) borate.
Examples 2 to 11
Examples 2 to 11 are also specific examples of the preparation of the electrolyte, and the parameters and preparation method are the same as in example 1 except that the composition ratios of the components of the electrolyte are added as shown in Table 1. The specific electrolyte formulations are shown in table 1.
Comparative examples 1 to 8
Comparative examples 1 to 8 the procedure of example 1 was followed except that the electrolyte was added in the composition ratio shown in Table 1. The specific electrolyte formulations are shown in table 1.
Table 1 electrolyte compositions of examples and comparative examples
Note that: the content of each component in the lithium salt is the mass percentage content in the electrolyte;
the content of the isocyanate compound is the mass percentage content in the electrolyte;
the content of each component in other additives is the mass percentage content in the electrolyte;
the proportion of each component in the solvent is mass ratio.
Preparation of a ternary battery:
and (3) fully stirring and uniformly mixing the positive electrode active substance NCM622, the conductive agent acetylene black and the binder polyvinylidene fluoride in an N-methyl pyrrolidone system according to a mass ratio of 95:3:2, coating the mixture on an aluminum foil, drying and cold pressing to obtain the positive electrode plate.
And fully stirring and uniformly mixing negative active material artificial graphite, conductive agent super carbon black, thickener sodium carboxymethylcellulose and binder styrene-butadiene rubber in a deionized water solvent system according to a mass ratio of 95:1:2:2, coating the mixture on a copper foil, drying, and cold pressing to obtain the negative electrode plate.
Polyethylene is used as a base film, and a nano alumina coating is coated on the base film to be used as a diaphragm.
And sequentially stacking the positive plate, the diaphragm and the negative plate, enabling the diaphragm to be positioned between the positive plate and the negative plate to play a role in isolation, and winding to obtain the bare cell. And placing the bare cell in an outer package, injecting the prepared electrolyte, and carrying out the procedures of packaging, placing, forming, aging, secondary packaging, capacity division and the like to obtain the NCM 622/graphite lithium ion battery.
Lithium ion battery performance test method
(1) And (3) testing normal temperature cycle performance: the ternary/graphite lithium ion battery is charged to 4.35V according to a constant current and a constant voltage of 1C at 25 ℃, the cut-off current is 0.05C, and then the ternary/graphite lithium ion battery is discharged to 3.0V according to the constant current of 1C. The 500 th cycle capacity retention rate was calculated after 500 cycles of charge/discharge. The calculation formula is as follows:
500 th week capacity retention = 500 th week cycle discharge capacity/first week cycle discharge capacity x 100%.
(2) High temperature storage performance at 60 ℃): and (3) charging and discharging the ternary/graphite lithium ion battery once at the room temperature according to the temperature of 1C, and recording the initial capacity by cutting off the current of 0.05C. Then, the battery is fully charged according to the constant current and constant voltage of 1C, and the initial thickness and the initial internal resistance of the battery are tested; placing the full-charge battery in a constant temperature environment at 60 ℃ for 14 days, and calculating the thermal expansion rate; after the battery is cooled to normal temperature for 6 hours, discharging to 3.0V according to 1C, recording the residual capacity of the battery, and calculating the residual capacity of the battery according to the following calculation formula:
battery thermal state expansion ratio (%) = (thermal thickness-initial thickness)/initial thickness×100%;
battery capacity remaining rate (%) =remaining capacity/initial capacity×100%;
battery capacity recovery rate (%) =recovery capacity/initial capacity×100%
Table 2 battery performance of each of examples and comparative examples
As can be seen from examples 1 to 11 and comparative examples 1 to 8, the lithium ion batteries using the electrolytes of examples 1 to 11 were superior to those of comparative examples 1 to 8 in both normal temperature cycle performance and high temperature storage performance. This is because the nonaqueous electrolyte of the high-voltage lithium ion battery of the invention is prepared by optimizing the formula under the combined action of three components (isocyanate containing sulfonyl structure, specific oxalate and silane additives) which are uniquely combined: the positive and negative electrodes of the isocyanate additive containing the sulfonyl structure form a film, so that the gas production is inhibited, and the impedance increase in the circulating and storing processes is inhibited; the oxalate additive plays a film forming role, and simultaneously optimizes the film impedance through the isocyanate additive containing sulfonyl structure, and inhibits the gas production side effect of oxalate; oxidation stability of EC and Li enhancement by silicate-containing borate additives + Migration number.
The electrolyte provided by the invention can enable stable CEI and SEI films to be generated in the battery, reduce the oxidation rate of the electrolyte on the surface of the positive electrode under high voltage, reduce the increase of the impedance of the battery, remove water and inhibit acid, inhibit the side effect of lithium bifluoride oxalate borate, prevent gas generation, thereby ensuring that the high-voltage ternary-graphite battery has long cycle life, excellent high-temperature storage performance and reliable safety.
Comparative examples 6-8 data demonstrate that the introduction of an unsuitable additive combination affects the electrochemical performance of the cell; the data of comparative example 3 shows that the formula lack of other additives has limited effect only by adding the isocyanate compound containing the sulfonyl structure, and the battery cycle performance and the high-temperature storage performance are poor; compared with the examples, the capacity retention rate of the comparative examples 1 and 2, which are not added with the isocyanate compound containing the sulfonyl structure and circulated at normal temperature for 500 weeks, is slightly lower, and the high-temperature circulation performance is remarkably lower, which indicates that the interfacial film formed by the isocyanate compound containing the sulfonyl structure, other film forming additives and lithium salt additives in the electrolyte is excellent and stable, and the circulation and storage performance of the battery can be improved. Meanwhile, the comparison of the sulfonyl-structure-containing isocyanate compounds with several different substituents shows that M1, M4 and M5 can form a CEI film with low impedance and high quality, and the cycle performance is better, and the DCR is lower; and the comprehensive effect of M2 and M3 is poor; at the same amount added, M5 performs poorly in terms of thermal expansion.
It will be readily appreciated by those skilled in the art that the foregoing is merely illustrative of the present invention and is not intended to limit the invention, but any modifications, equivalents, improvements or the like which fall within the spirit and principles of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The ternary high-voltage lithium ion battery nonaqueous electrolyte is characterized by comprising a nonaqueous organic solvent, electrolyte lithium salt, a film-forming additive, an oxalate additive and a silane additive, wherein the electrolyte lithium salt is not oxalate, the film-forming additive comprises an isocyanate compound containing a sulfonyl structure, and the structural formula of the isocyanate compound is shown as the formula (I):
wherein the substituents R 1 、R 2 Independently selected from the group consisting of alkyl groups of 1-4 carbons, phenyl groups, fluoro groups, isocyanate groups.
2. The ternary high voltage lithium ion battery nonaqueous electrolyte according to claim 1, wherein the film forming additive comprises at least one of 1, 3-Propane Sultone (PS), fluoroethylene carbonate (FEC), vinylene Carbonate (VC), and ethylene sulfate (DTD); preferably, the mass percentage of the film forming additive in the electrolyte is 0.5-5%.
3. The ternary high voltage lithium ion battery nonaqueous electrolyte of claim 1 wherein the oxalate additive is selected from one or more of lithium difluorobis (oxalato) phosphate (lidafop), lithium difluorooxalato borate (lidafob), lithium tetrafluorooxalato phosphate (LTFOP), and lithium bisoxalato borate (LiBOB); preferably, the mass percentage of the oxalate additive in the electrolyte is 0.3-1.5%.
4. The ternary high voltage lithium ion battery nonaqueous electrolyte according to claim 1, wherein the silane additive is selected from one or more of tris (trimethylsilyl) phosphate (TMSP), tris (trimethylsilyl) borate (TMSB), tris (trimethylsilyl) phosphite (TMSPi); preferably, the mass percentage of the silane additive in the electrolyte is 0.1-2%.
5. The ternary high-voltage lithium ion battery nonaqueous electrolyte according to claim 1, wherein the isocyanate compound is at least one compound selected from the group consisting of compounds represented by the following structural formulas:
preferably, the mass percentage of the isocyanate compound in the electrolyte is 0.15-1.1%.
6. The ternary high voltage lithium ion battery nonaqueous electrolyte of claim 1 wherein the film forming additive is Vinylene Carbonate (VC) or ethylene sulfate (DTD) and the silane based additive is tris (trimethylsilyl) phosphate (TMSP) or tris (trimethylsilyl) borate (TMSB); wherein the mass percentage of the film forming additive in the electrolyte is 0.3-0.7%, and the mass percentage of the silane additive in the electrolyte is 0.3-1.2%; preferably, when the film-forming additive is ethylene sulfate (DTD), the oxalate additive does not contain lithium bis (oxalato) borate (LiBOB).
7. The three of claim 1The nonaqueous electrolyte of the high-voltage lithium ion battery is characterized in that the electrolyte lithium salt is selected from lithium hexafluorophosphate (LiPF) 6 ) Lithium bis (fluorosulfonyl) imide (LiLSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium difluorophosphate (LiPO) 2 F 2 ) Lithium tetrafluoroborate (LiBF) 4 ) One or more of the following; preferably, the mass percentage of the electrolyte lithium salt in the electrolyte is 10-20%.
8. The ternary high voltage lithium ion battery nonaqueous electrolyte according to claim 1, wherein the nonaqueous organic solvent is selected from one or more of Ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC), and ethylmethyl carbonate (EMC); preferably, the mass ratio of the Ethylene Carbonate (EC), the Propylene Carbonate (PC), the diethyl carbonate (DEC) and the ethylmethyl carbonate (EMC) is 20-30:5-15:15-25:40-50.
9. A ternary high voltage lithium ion battery comprising a positive electrode, a negative electrode, a separator and the ternary high voltage lithium ion battery nonaqueous electrolyte of any one of claims 1-9.
10. The ternary high voltage lithium ion battery of claim 9 wherein the active material of the positive electrode is a ternary NCM material; the negative electrode is made of one or more of natural graphite, artificial graphite, lithium titanate, silicon-oxygen negative electrode and silicon negative electrode; preferably, the upper limit cutoff voltage of the high voltage is 4.35-4.5V.
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