CN116598587A - Electrolyte and lithium ion battery - Google Patents
Electrolyte and lithium ion battery Download PDFInfo
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- CN116598587A CN116598587A CN202310490334.0A CN202310490334A CN116598587A CN 116598587 A CN116598587 A CN 116598587A CN 202310490334 A CN202310490334 A CN 202310490334A CN 116598587 A CN116598587 A CN 116598587A
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 70
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 15
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 14
- 239000000654 additive Substances 0.000 claims abstract description 111
- 230000000996 additive effect Effects 0.000 claims abstract description 109
- 150000003839 salts Chemical class 0.000 claims abstract description 12
- 239000003960 organic solvent Substances 0.000 claims abstract description 8
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 4
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 3
- IAHFWCOBPZCAEA-UHFFFAOYSA-N succinonitrile Chemical compound N#CCCC#N IAHFWCOBPZCAEA-UHFFFAOYSA-N 0.000 claims description 6
- MYWOJODOMFBVCB-UHFFFAOYSA-N 1,2,6-trimethylphenanthrene Chemical compound CC1=CC=C2C3=CC(C)=CC=C3C=CC2=C1C MYWOJODOMFBVCB-UHFFFAOYSA-N 0.000 claims description 5
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical group O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 claims description 5
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 4
- 238000003860 storage Methods 0.000 abstract description 17
- 230000014759 maintenance of location Effects 0.000 description 18
- 238000012360 testing method Methods 0.000 description 11
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 238000002161 passivation Methods 0.000 description 9
- 239000007784 solid electrolyte Substances 0.000 description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 7
- 229910052744 lithium Inorganic materials 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 6
- 239000002002 slurry Substances 0.000 description 6
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- -1 hexafluorophosphate Chemical compound 0.000 description 5
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 description 4
- 125000000524 functional group Chemical group 0.000 description 4
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 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 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 125000003837 (C1-C20) alkyl group Chemical group 0.000 description 2
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 2
- JGFBQFKZKSSODQ-UHFFFAOYSA-N Isothiocyanatocyclopropane Chemical compound S=C=NC1CC1 JGFBQFKZKSSODQ-UHFFFAOYSA-N 0.000 description 2
- 229910013872 LiPF Inorganic materials 0.000 description 2
- 101150058243 Lipf gene Proteins 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 150000008065 acid anhydrides Chemical group 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- PWLNAUNEAKQYLH-UHFFFAOYSA-N butyric acid octyl ester Natural products CCCCCCCCOC(=O)CCC PWLNAUNEAKQYLH-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000000536 complexating effect Effects 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 125000004185 ester group Chemical group 0.000 description 2
- WBJINCZRORDGAQ-UHFFFAOYSA-N formic acid ethyl ester Natural products CCOC=O WBJINCZRORDGAQ-UHFFFAOYSA-N 0.000 description 2
- 150000003949 imides Chemical class 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- UUIQMZJEGPQKFD-UHFFFAOYSA-N n-butyric acid methyl ester Natural products CCCC(=O)OC UUIQMZJEGPQKFD-UHFFFAOYSA-N 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 125000001424 substituent group Chemical group 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 2
- 125000001889 triflyl group Chemical group FC(F)(F)S(*)(=O)=O 0.000 description 2
- MFGALGYVFGDXIX-UHFFFAOYSA-N 2,3-Dimethylmaleic anhydride Chemical compound CC1=C(C)C(=O)OC1=O MFGALGYVFGDXIX-UHFFFAOYSA-N 0.000 description 1
- AYKYXWQEBUNJCN-UHFFFAOYSA-N 3-methylfuran-2,5-dione Chemical compound CC1=CC(=O)OC1=O AYKYXWQEBUNJCN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229910012820 LiCoO Inorganic materials 0.000 description 1
- 229910010710 LiFePO 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
- 239000007983 Tris buffer Substances 0.000 description 1
- SOXUFMZTHZXOGC-UHFFFAOYSA-N [Li].[Mn].[Co].[Ni] Chemical compound [Li].[Mn].[Co].[Ni] SOXUFMZTHZXOGC-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
- 239000006230 acetylene black Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000000872 buffer Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000011883 electrode binding agent Substances 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 150000002430 hydrocarbons Chemical group 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000002153 silicon-carbon composite material Substances 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
- 238000004804 winding Methods 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
Abstract
The application discloses electrolyte and a lithium ion battery, and relates to the technical field of batteries, wherein the electrolyte comprises electrolyte salt, an organic solvent and an additive, and the additive at least comprises an additive A and an additive B; the additive A has the following structural formula I:wherein X is independently selected from any one of the following structural formulas 1 to 4, and the terminal is connected with-c=c;the additive B has the following structural formula II:wherein R is 1 And R is 2 Independently selected from alkyl groups having 1 to 20 carbon atoms; additive A in electrolyteThe mass ratio is 0.3-9.5%; the mass ratio of the additive B in the electrolyte is 5-15%. The electrolyte provided by the application can improve the high-temperature long-cycle performance, the high-temperature storage performance and the safety performance of the battery.
Description
Technical Field
The application relates to the technical field of batteries, in particular to electrolyte and a lithium ion battery.
Background
Lithium ion batteries have the advantages of high specific energy density, long cycle life and the like, and are widely used in various electronic products, and in recent years, are also widely used in electric vehicles, various electric tools and energy storage devices. Along with the improvement of the living standard of people and the trend of better life, higher requirements are also put on the energy density of the battery. And forming the silicon-carbon anode material by compounding the silicon-carbon material. In the silicon-carbon composite material, silicon is used as an active substance to improve the lithium storage capacity; the carbon can buffer the volume change of the silicon cathode in the charge-discharge process to a certain extent and improve the conductivity of the silicon-based material. Therefore, developing an electrolyte that matches with a silicon-carbon negative electrode material has become a hotspot for lithium battery electrolyte research.
High pressure silicon carbon electrolyte is taken as an example, although high pressure silicon carbon electrolyte has great attraction in improving the capacity of lithium ion batteries. However, the high-voltage silicon-carbon electrolyte faces a series of problems that the surface of the negative electrode cannot repeatedly and stably form a solid electrolyte passivation film (SEI film), the active sites of silicon are exposed, and the like, and the high-temperature long-cycle performance, the high-temperature storage performance and the service life of the battery are deteriorated.
At present, the battery performance is improved by adding the additive, namely, the ethylene carbonate, to the high-voltage silicon-carbon electrolyte, wherein the addition of the ethylene carbonate can form a solid electrolyte passivation film (SEI film) on the surface of a negative electrode, but the solid electrolyte passivation film (SEI film) is not compact, has poor flexibility and is easy to lose effectiveness, and the addition of the ethylene carbonate also increases the battery impedance, so that the high-temperature long-cycle performance, the high-temperature storage performance and the service life of the battery still cannot be effectively improved.
Disclosure of Invention
The application aims to provide an electrolyte and a lithium ion battery, which can effectively improve the high-temperature long-cycle performance, the high-temperature storage performance and the safety performance of the battery.
The application discloses an electrolyte, which comprises electrolyte salt, an organic solvent and an additive, wherein the additive at least comprises an additive A and an additive B;
the additive A has the following structural formula I:
wherein X is independently selected from any one of the following structural formulas 1 to 4, and the terminal is connected with-c=c;
the additive B has the following structural formula II:
wherein R is 1 And R is 2 Independently selected from alkyl groups having 1 to 20 carbon atoms; the mass ratio of the additive A in the electrolyte is 0.3-9.5%; the mass ratio of the additive B in the electrolyte is 5-15%.
Optionally, the additive A is at least one of the following structural formulas I-1 to I-3:
optionally, the additive B is at least one of the following structural formulas II-1 to II-3:
optionally, the additive A is pentaerythritol tetraacrylate; the structural formula is as follows:
optionally, the additive B is maleic anhydride; the structural formula is as follows:
optionally, the additive further comprises an additive C, wherein the additive C at least comprises 1, 3-propane sultone, succinonitrile, hexadinitrile and 1,3, 6-hexanetrinitrile; the mass ratio of the additive C in the electrolyte is 5-10%.
Optionally, the mass ratio of the additive A in the electrolyte is 1% -5%.
Optionally, the mass ratio of the additive B in the electrolyte is 9% -11%.
Optionally, the mass ratio of the additive C in the electrolyte is 6% -8%.
The application also discloses a lithium ion battery comprising the electrolyte.
According to the electrolyte, the unsaturated functional groups contained in the electrolyte are reduced on the negative electrode side in preference to the solvent in the battery formation stage through the addition of the additive A, a plurality of double bond functional groups can be polymerized, the generated polymer has stronger flexibility and reducibility compared with the traditional vinylene carbonate, a layer of compact and stable solid electrolyte passivation film (SEI) is formed on the surface of the negative electrode, the high-temperature long-cycle stability, the high-temperature storage performance and the long-cycle life of the battery are improved, and in addition, the kinetic performance of the electrolyte can be improved again due to the ester groups contained in the additive A, and the cycle life of the battery is further improved. Meanwhile, through the addition of the additive B, the additive B is acid anhydride, and can be combined with water and free acid in electrolyte to protect a formed solid electrolyte passivation film (SEI) from being damaged; in addition, the additive B can also form a film again in the battery formation stage, a compact and repairable solid electrolyte passivation film (SEI) structural layer is formed again, the cycle stability of the battery is improved again, meanwhile, the addition of the additive B can also reduce the impedance of the battery, the negative electrode is protected together under the cooperative and matched use of the additive A and the additive B, the stability of the silicon negative electrode side is improved, and the long cycle performance, the high temperature performance and the long cycle life of the battery are effectively improved.
Detailed Description
It is to be understood that the terminology used herein, the specific structural and functional details disclosed are merely representative for the purpose of describing particular embodiments, but that the application may be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.
The application is described in detail below with reference to alternative embodiments.
As an embodiment of the present application, an electrolyte is disclosed, comprising an electrolyte salt, an organic solvent, and an additive, the additive comprising an additive a, an additive B, and an additive C;
the additive A has the following structural formula I:
wherein X is independently selected from any one of the following structural formulas 1-4, wherein the terminal is connected to-c=c;
the additive B has the following structural formula II:
wherein R is 1 And R is 2 Independently selected from C1-20 alkyl groups, when R 1 ～R 2 When each is independently selected from the group consisting of C1-C20 alkyl groups, the specific type of alkyl group is not particularly limited and may be selected according to the actual requirements, for exampleFor example, both a chain group and a cyclic group may be used, wherein the chain hydrocarbon group includes a straight chain group and a branched chain group, and the cyclic group may have a substituent or may not have a substituent.
The mass ratio of the additive A in the electrolyte is 0.5% -9.5%, and the additive A can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% and 9.5%.
The mass ratio of the additive B in the electrolyte is 5% -15%, and the additive B can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% and 15%.
More specifically, the additive A is at least one of the following structural formulas I-1 to I-3:
wherein, the formula I-1 is pentaerythritol tetraacrylate, the formula I-2 is pentaerythritol difluoro tetrabutenate, and the formula I-3 is pentaerythritol hexafluorotetrabutenate.
More specifically, the additive B is at least one of the following structural formulas II-1 to II-3:
wherein, the formula II-1 is maleic anhydride, the formula II-2 is methyl maleic anhydride, and the formula II-3 is dimethyl maleic anhydride.
More specifically, additive a is pentaerythritol tetraacrylate; the structural formula is as follows:
more specifically, additive B is maleic anhydride; the structural formula is as follows:
more specifically, the additive also comprises an additive C, wherein the additive C at least comprises 1, 3-Propane Sultone (PS), succinonitrile (SN), hexadinitrile (ADN) and 1,3, 6-Hexanetrinitrile (HTCN), the mass ratio of the additive C in the electrolyte is 5% -10%, and the additive C can be 6%, 7%, 8%, 9% and 10%.
The additive C can act on the anode and the cathode in a targeted manner, mainly plays roles of forming a film on the cathode and complexing the anode, and can protect the cathode together under the synergistic cooperation of the additive A, the additive B and the additive C, so that the stability of the silicon cathode side is improved, and the long-cycle performance, the high-temperature performance and the long-cycle life of the battery are effectively improved.
The organic solvent of the present embodiment is selected from at least two of Ethylene Carbonate (EC), propylene Carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl Formate (MF), ethyl Formate (EF), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), tetrahydrofuran (THF).
The organic solvents of this example include Ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC) and Propyl Propionate (PP).
The electrolyte salt of the present embodiment is optionally at least one of an organic lithium salt or an inorganic lithium salt, wherein the electrolyte salt of the present embodiment is at least one selected from a compound containing fluorine element and lithium element, and the electrolyte salt specifically used is at least one selected from hexafluorophosphate, hexafluoroarsenate, perchlorate, lithium trifluorosulfonyl, lithium difluoro (trifluoromethylsulfonyl) imide, lithium tris (trifluoromethylsulfonyl) imide, lithium difluoroimide sulfonate, and the electrolyte salt of the present embodiment is hexafluorophosphate.
The electrolyte salt concentration of this example may be 0.5mol/L to 1.5mol/L, and the electrolyte salt concentration may be 0.5mol/L, 0.6mol/L, 0.7mol/L, 0.8mol/L, 0.9mol/L, 1.0mol/L, 1.1mol/L, 1.2mol/L, 1.3mol/L, 1.4mol/L, 1.5mol/L. The concentration of electrolyte salt is too low, and the conductivity of electrolyte is low, so that the multiplying power and the cycle performance of the whole battery system can be influenced; too high an electrolyte salt concentration and too high an electrolyte viscosity also affect the rate of the overall battery system.
According to the electrolyte, the unsaturated functional groups contained in the electrolyte are reduced on the negative electrode side in preference to the solvent in the battery formation stage through the addition of the additive A, a plurality of double bond functional groups can be polymerized, the generated polymer has stronger flexibility and reducibility compared with the traditional vinylene carbonate, a layer of compact and stable solid electrolyte passivation film (SEI) is formed on the surface of the negative electrode, the high-temperature long-cycle stability, the high-temperature storage performance and the long-cycle life of the battery are improved, and in addition, the kinetic performance of the electrolyte can be improved again due to the ester groups contained in the additive A, and the cycle life of the battery is further improved. Meanwhile, through the addition of the additive B, the additive B is acid anhydride, and can be combined with water and free acid in electrolyte to protect a formed solid electrolyte passivation film (SEI) from being damaged; in addition, the additive B can also form a film again in the formation stage, a compact and repairable solid electrolyte passivation film (SEI) structural layer is formed again, the circulation stability of the battery is improved again, meanwhile, the addition of the additive B can also reduce the impedance of the battery, the additive C can act on the anode and the cathode in a targeted manner, the film forming and the anode complexing effects of the cathode are mainly achieved, the cathode is protected together under the cooperative cooperation of the additive A, the additive B and the additive C, the stability of the silicon cathode side is improved, and the long circulation performance, the high-temperature performance and the long circulation life of the battery are effectively improved.
The electrolyte preparation process of this example:
ethylene Carbonate (EC), polycarbonate (PC), diethyl carbonate (DEC) and Propyl Propionate (PP) were mixed at a mass ratio of 1:1:2:6 as organic solvents. Adding additive C, which is 1, 3-Propane Sultone (PS), succinonitrile (SN), hexadinitrile (ADN) and 1,3, 6-Hexanetrinitrile (HTCN), into organic solvent, mixing uniformly, adding lithium hexafluorophosphate (LiPF) 6 ) Obtain lithium hexafluorophosphate (LiPF) 6 ) The electrolyte of this example was obtained by adding the corresponding additive A and the corresponding additive B to the mixed solution having a concentration of 1.1 mol/L.
Specifically, the additive A is pentaerythritol tetraacrylate, and the structural formula is as follows:
the additive B is maleic anhydride and has the structural formula:
as another embodiment of the present application, a lithium ion battery is disclosed, comprising the above electrolyte; the battery also comprises a positive pole piece, a negative pole piece and a separation film between the positive pole piece and the negative pole piece.
The positive electrode plate comprises a positive electrode current collector and a positive electrode active slurry layer positioned on the positive electrode current collector, wherein the positive electrode active slurry layer comprises a positive electrode active material;
the negative electrode plate comprises a negative electrode current collector and a negative electrode active slurry layer positioned on the negative electrode current collector, wherein the negative electrode active slurry layer comprises a negative electrode active material.
The specific types of the positive electrode active material, the positive electrode binder and the negative electrode active material are not particularly limited, and may be selected according to requirements.
The positive electrode active material in this embodiment is selected from lithium cobaltate (LiCoO) 2 ) Ternary materials of lithium nickel manganese cobalt, lithium iron phosphate (LiFePO) 4 ) Lithium manganate (LiMn) 2 O 4 ) One or more of the following.
Manufacturing a positive electrode plate:
and fully stirring and mixing the positive electrode active substance LCO and the conductive agent CNT in an N-methylpyrrolidone solvent according to the weight ratio of 97:1.5:1.5 of the binder polyvinylidene fluoride to form uniform positive electrode slurry. And (3) coating the slurry on an Al foil of the positive current collector, drying, and cold pressing to obtain the positive pole piece.
Manufacturing a negative electrode plate:
and (3) fully stirring and mixing the negative electrode active material graphite, the conductive agent acetylene black, the adhesive styrene-butadiene rubber and the thickener sodium carboxymethyl cellulose in a proper amount of deionized water solvent according to a mass ratio of 95:2:2:1, so that uniform negative electrode slurry is formed. And (3) coating the slurry on a negative current collector Cu foil, drying, and cold pressing to obtain a negative electrode plate.
Examples:
manufacturing a lithium ion battery:
sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, enabling the isolating film to be positioned between the positive electrode plate and the negative electrode plate, playing an isolating role, and then winding to obtain the bare cell. And (3) placing the bare cell in an outer packaging bag, respectively injecting the electrolyte in the table 1 into the dried battery, and performing the procedures of vacuum packaging, standing, formation, shaping and the like to complete the preparation of the lithium ion battery, thereby obtaining the lithium ion battery.
The lithium ion battery performance test passed the following two tests:
high temperature cycle testing of batteries
The testing method comprises the following steps: and placing the battery in an environment of 45+/-2 ℃, and calculating the capacity retention rate of the battery after circulation according to standard charge-discharge circulation, circulation multiplying power of 1C and charging voltage of 3.0-4.5V. The calculation formula is as follows: the nth cycle capacity retention (%) = (nth cycle discharge capacity)/(first cycle discharge capacity) ×100%.
High temperature storage test of battery:
the testing method comprises the following steps: and (3) charging the battery core with the separated capacity to 4.5V at normal temperature at 0.5C, placing the full-charge battery in an environment of 85 ℃ for 6 hours, thermally measuring the thickness expansion rate, and after the battery core is restored to the room temperature, discharging to 3.0V at 0.5C, and recording the discharge capacity.
The battery test conditions are shown in table 2.
The compositions of the components and additives added to the electrolytes of examples 1 to 7 and comparative examples 1 to 8 are shown in Table 1:
TABLE 1
The results of examples 1 to 7 and comparative examples 1 to 8 are shown in Table 2:
TABLE 2
The test results of examples 1-6 and comparative examples 1-3 show that the additive A and the additive B are added to greatly improve the high-temperature cycle capacity retention rate and the safety performance of the battery at 45 ℃ and the high-temperature storage capacity retention rate and the safety performance of the battery at 85 ℃.
The test results of examples 1 to 7 show that the performance of the additive A shows a tendency of increasing and decreasing with increasing addition, wherein the effect of example 3 is optimal, so that the addition of the corresponding additive A and additive B has a synergistic effect, protects the negative electrode together, prevents electrolyte from decomposing, improves the stability of the silicon negative electrode side, improves the high-temperature cycle capacity retention rate and safety performance at 45 ℃, improves the high-temperature storage capacity retention rate and safety performance at 85 ℃, particularly obviously reduces the thickness expansion rate in the high-temperature cycle at 45 ℃ and the high-temperature storage at 85 ℃, improves the safety performance of the battery, ensures that the thickness expansion rate of 300 cycles at 45 ℃ is only 1.27%, the thickness expansion rate of 500 cycles is only 3.84%, and the thickness expansion rate of 800 cycles is only 6.42%.
Comparative example 1 shows that in the system without additive a, the high-temperature cycle capacity retention rate and the high-temperature storage capacity retention rate of the battery are reduced, and the thickness expansion rate of the battery is slightly deteriorated.
Comparative example 2 shows that the high-temperature cycle capacity retention rate and the high-temperature storage capacity retention rate of the battery are seriously deteriorated and the thickness expansion rate is higher in the system without the additives a and B, and there is a great potential safety hazard.
Comparative example 3 shows that the high-temperature cycle capacity retention rate and the high-temperature storage capacity retention rate of the battery in the system without the additive B added
The thickness expansion rate is higher, and the potential safety hazard is large.
The test results of comparative examples 4 to 5 show that the additive amount of additive a or additive B is too large or too small (i.e., a value outside the protection range of this example) both deteriorate the 45 ℃ high-temperature cycle capacity retention rate and safety performance of the battery, and the 85 ℃ high-temperature storage capacity retention rate and safety performance of the battery.
The test results of comparative examples 6 to 7 show that the additive amount of additive A and additive B is too large or too small (i.e., values outside the protection range of this example) seriously deteriorate the high-temperature cycle capacity retention rate and safety performance of the battery at 45℃and the high-temperature storage capacity retention rate and safety performance of the battery at 85 ℃.
The test result of comparative example 8 shows that the effect of improving the high-temperature cycle capacity retention rate and the safety performance of the battery at 45 ℃ and the high-temperature storage capacity retention rate and the safety performance of the battery at 85 ℃ is not obvious by adopting the ethylene carbonate as the additive and not adding the additive A and the additive B.
The above description of the application in connection with specific alternative embodiments is further detailed and it is not intended that the application be limited to the specific embodiments disclosed. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the application, and these should be considered to be within the scope of the application.
Claims (10)
1. An electrolyte is characterized by comprising electrolyte salt, an organic solvent and an additive, wherein the additive at least comprises an additive A and an additive B;
the additive A has the following structural formula I:
wherein X is independently selected from any one of the following structural formulas 1 to 4, and the terminal is connected with-c=c;
the additive B has the following structural formula II:
wherein R is 1 And R is 2 Independently selected from alkyl groups having 1 to 20 carbon atoms;
the mass ratio of the additive A in the electrolyte is 0.3-9.5%; the mass ratio of the additive B in the electrolyte is 5% -15%; .
2. The electrolyte of claim 1, wherein the additive a is at least one of the following structural formulas i-1 to i-3:
3. the electrolyte of claim 1, wherein the additive B is at least one of the following structural formulas ii-1 to ii-3:
4. the electrolyte of claim 1 wherein additive a is pentaerythritol tetraacrylate having the formula:
5. the electrolyte of claim 1 wherein the additive B is maleic anhydride having the formula:
6. the electrolyte of claim 1 wherein the additive further comprises additive C comprising at least 1, 3-propane sultone, succinonitrile, hexadinitrile and 1,3, 6-hexanetrinitrile; the mass ratio of the additive C in the electrolyte is 5-10%.
7. The electrolyte according to claim 1, wherein the mass ratio of the additive a in the electrolyte is 1-5%.
8. The electrolyte according to claim 1, wherein the mass ratio of the additive B in the electrolyte is 9-11%.
9. The electrolyte according to claim 6, wherein the mass ratio of the additive C in the electrolyte is 6-8%.
10. A lithium ion battery comprising an electrolyte as claimed in any one of claims 1 to 9.
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