CN116632345A - Lithium ion battery electrolyte and lithium ion battery - Google Patents
Lithium ion battery electrolyte and lithium ion battery Download PDFInfo
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- CN116632345A CN116632345A CN202310564123.7A CN202310564123A CN116632345A CN 116632345 A CN116632345 A CN 116632345A CN 202310564123 A CN202310564123 A CN 202310564123A CN 116632345 A CN116632345 A CN 116632345A
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- additive
- lithium
- ion battery
- electrolyte
- lithium ion
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 51
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 38
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 36
- 239000000654 additive Substances 0.000 claims abstract description 89
- 230000000996 additive effect Effects 0.000 claims abstract description 89
- 239000002904 solvent Substances 0.000 claims abstract description 28
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 13
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 13
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 12
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 8
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims abstract description 8
- 125000001424 substituent group Chemical group 0.000 claims abstract description 8
- 125000001153 fluoro group Chemical group F* 0.000 claims abstract description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 239000011574 phosphorus Substances 0.000 claims abstract description 6
- 150000001336 alkenes Chemical class 0.000 claims abstract description 4
- 125000003342 alkenyl group Chemical group 0.000 claims abstract description 4
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims abstract description 4
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims abstract description 4
- 125000004430 oxygen atom Chemical group O* 0.000 claims abstract description 4
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 claims abstract description 4
- 150000001345 alkine derivatives Chemical class 0.000 claims abstract 2
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 claims abstract 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 14
- 229910052744 lithium Inorganic materials 0.000 claims description 14
- 239000012528 membrane Substances 0.000 claims description 12
- 239000007774 positive electrode material Substances 0.000 claims description 10
- 239000006258 conductive agent Substances 0.000 claims description 8
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 7
- 239000011230 binding agent Substances 0.000 claims description 6
- 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 6
- 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 6
- 239000007773 negative electrode material Substances 0.000 claims description 6
- WVLBCYQITXONBZ-UHFFFAOYSA-N trimethyl phosphate Chemical group COP(=O)(OC)OC WVLBCYQITXONBZ-UHFFFAOYSA-N 0.000 claims description 6
- KOMNUTZXSVSERR-UHFFFAOYSA-N 1,3,5-tris(prop-2-enyl)-1,3,5-triazinane-2,4,6-trione Chemical compound C=CCN1C(=O)N(CC=C)C(=O)N(CC=C)C1=O KOMNUTZXSVSERR-UHFFFAOYSA-N 0.000 claims description 5
- 229910013870 LiPF 6 Inorganic materials 0.000 claims description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- 239000010439 graphite Substances 0.000 claims description 4
- 229910002804 graphite Inorganic materials 0.000 claims description 4
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910013075 LiBF Inorganic materials 0.000 claims description 3
- 229910019142 PO4 Inorganic materials 0.000 claims description 3
- 239000007770 graphite material Substances 0.000 claims description 3
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 3
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 3
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 3
- 239000010452 phosphate Substances 0.000 claims description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 230000000052 comparative effect Effects 0.000 description 14
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 8
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 8
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 8
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 7
- 238000003860 storage Methods 0.000 description 6
- 125000002029 aromatic hydrocarbon group Chemical group 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- JYEUMXHLPRZUAT-UHFFFAOYSA-N 1,2,3-triazine Chemical group C1=CN=NN=C1 JYEUMXHLPRZUAT-UHFFFAOYSA-N 0.000 description 2
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 2
- GWAOOGWHPITOEY-UHFFFAOYSA-N 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide Chemical compound O=S1(=O)CS(=O)(=O)OCO1 GWAOOGWHPITOEY-UHFFFAOYSA-N 0.000 description 2
- VTHRQKSLPFJQHN-UHFFFAOYSA-N 3-[2-(2-cyanoethoxy)ethoxy]propanenitrile Chemical compound N#CCCOCCOCCC#N VTHRQKSLPFJQHN-UHFFFAOYSA-N 0.000 description 2
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 125000002355 alkine group Chemical group 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 2
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000006864 oxidative decomposition reaction Methods 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- IAHFWCOBPZCAEA-UHFFFAOYSA-N succinonitrile Chemical compound N#CCCC#N IAHFWCOBPZCAEA-UHFFFAOYSA-N 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 229930195735 unsaturated hydrocarbon Natural products 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- ZPFAVCIQZKRBGF-UHFFFAOYSA-N 1,3,2-dioxathiolane 2,2-dioxide Chemical compound O=S1(=O)OCCO1 ZPFAVCIQZKRBGF-UHFFFAOYSA-N 0.000 description 1
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 description 1
- UHOPWFKONJYLCF-UHFFFAOYSA-N 2-(2-sulfanylethyl)isoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCS)C(=O)C2=C1 UHOPWFKONJYLCF-UHFFFAOYSA-N 0.000 description 1
- SXAMGRAIZSSWIH-UHFFFAOYSA-N 2-[3-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]-1,2,4-oxadiazol-5-yl]-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C1=NOC(=N1)CC(=O)N1CC2=C(CC1)NN=N2 SXAMGRAIZSSWIH-UHFFFAOYSA-N 0.000 description 1
- JVKRKMWZYMKVTQ-UHFFFAOYSA-N 2-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]pyrazol-1-yl]-N-(2-oxo-3H-1,3-benzoxazol-6-yl)acetamide Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)C=1C=NN(C=1)CC(=O)NC1=CC2=C(NC(O2)=O)C=C1 JVKRKMWZYMKVTQ-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000006183 anode active material Substances 0.000 description 1
- 239000006256 anode slurry Substances 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding 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 invention discloses lithium ion battery electrolyte and a lithium ion battery, wherein the lithium ion battery electrolyte comprises lithium salt, a solvent and an additive, and the additive comprises an additive A and a phosphorus-containing additive B; the general formula of the additive A is shown in the following formula I:the general formula of the additive B is shown in the following formulas II, III and IV:in the formula I, R 1 ～R 3 Each independently selected from any one of a hydrogen atom, a fluorine atom, an alkyl group and a substituent thereof, an alkenyl group and a substituent thereof; in the formulas II, III and IV, X1, X2, X3 and X4 are selected from any one of alkyl, fluorine atom, hydrogen atom, halogenated alkyl, olefin, alkyne, aromatic alkyl and halogenated aromatic alkyl, R 4 One selected from methyl, ethyl, propyl and oxygen atoms; wherein the additive A and the additive B both account for 0.2-3% of the electrolyte by mass.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to lithium ion battery electrolyte and a lithium ion battery.
Background
Lithium batteries are classified into lithium batteries and lithium ion batteries, and lithium ion batteries are used for mobile phones and notebook computers. The lithium ion battery has the advantages of high specific energy, no memory effect, long cycle life, small self-discharge and the like, and is widely applied to the fields of digital codes, energy storage, electric automobiles and the like.
With the increasing demands of mobile office in recent years, higher demands are put on application environments of lithium ion batteries, such as notebook batteries, and higher high-temperature storage and low-temperature discharge performance and longer cycle life are required.
Disclosure of Invention
The invention aims to provide lithium ion battery electrolyte and a lithium ion battery, which can prolong the cycle life of the battery and simultaneously give consideration to high and low temperature performance.
The invention discloses lithium ion battery electrolyte, which comprises lithium salt, a solvent and an additive, wherein the additive comprises an additive A and a phosphorus-containing additive B; the general formula of the additive A is shown in the following formula I:
the general formula of the additive B is shown in the following formulas II, III and IV:
in the formula I, R 1 ～R 3 Each independently selected from any one of a hydrogen atom, a fluorine atom, an alkyl group and a substituent thereof, an alkenyl group and a substituent thereof; a formula II, III,In IV, X1, X2, X3 and X4 are selected from any one of alkyl, fluorine atom, hydrogen atom, halogenated alkyl, olefin group, alkyne group, aromatic hydrocarbon group and halogenated aromatic hydrocarbon group, and R4 is selected from one of methyl, ethyl, propyl and oxygen atom;
wherein the additive A and the additive B both account for 0.2-3% of the electrolyte by mass.
Optionally, the additive A is triallyl isocyanurate, and the triallyl isocyanurate accounts for 1% of the mass of the electrolyte.
Optionally, the additive B is trimethyl phosphate, and the trimethyl phosphate accounts for 1% of the mass of the electrolyte.
Alternatively, the concentration of lithium salt in the electrolyte is 0.9M to 2M.
Alternatively, the concentration of lithium salt in the electrolyte is 1.0M to 1.3M.
Alternatively, the lithium salt comprises lithium hexafluorophosphate (LiPF 6 ) Lithium difluorooxalato borate (LiODFB), lithium difluorodioxaato phosphate (LiDFOP), lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), lithium difluorophosphate (LiPOF) 2 ) At least one of (a) and (b).
Optionally, the solvent comprises EC, PC, DEC and PP; the mass ratio of EC in the solvent is 10% -30%, the mass ratio of PC in the solvent is 10% -30%, and the mass ratio of DEC in the solvent is 10% -30%; the mass ratio of the PP in the solvent is 30% -60%.
The invention also discloses a lithium ion battery, which comprises a positive plate, a negative plate, a diaphragm and the electrolyte.
Optionally, the mass ratio of the total content of the P element in the positive plate and the negative plate of the lithium ion battery is not lower than 120ppm.
Optionally, the positive electrode plate comprises a positive electrode current collector and a positive electrode membrane, the negative electrode plate comprises a negative electrode current collector and a negative electrode membrane, the positive electrode membrane comprises a positive electrode active material, a conductive agent and a binder, and the negative electrode membrane comprises a negative electrode active material, a conductive agent and a binder; the positive electrode active material comprises lithium cobaltate, ternary lithium iron phosphate and/or one or more of graphite and/or silicon, the positive electrode active material is preferably lithium cobaltate, and the negative electrode active material is graphite material.
According to the lithium ion battery electrolyte, the additive A and the additive B are added, so that the triazine ring structure in the additive A is active in nature, and can be oxidized on the surface of the positive electrode preferentially, meanwhile, unsaturated hydrocarbon substances can undergo open-chain polymerization, and the formed film has the characteristics of compactness, solvent resistance and the like, so that the reactivity of the surface of the electrode is reduced, and the oxidative decomposition of the electrolyte at a high temperature is reduced. And the phosphorus-containing additive B can participate in the formation of an SEI film at the negative electrode, and the formed SEI film is rich in P element, has lower interface impedance and is beneficial to the passage of Li ions. The additive A and the additive B are matched for use, so that the thermal stability and the cycle performance of the battery can be improved, the service life of the battery can be prolonged, and the low-temperature performance can be 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 invention may be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.
The invention is described in detail below with reference to alternative embodiments.
As an embodiment of the present invention, there is disclosed 1. A lithium ion battery electrolyte, characterized by comprising a lithium salt, a solvent, and an additive, the additive comprising an additive a and a phosphorus-containing additive B; the general formula of the additive A is shown in the following formula I:
the general formula of the additive B is shown in the following formulas II, III and IV:
in the formula I, R 1 ～R 3 Each independently selected from the group consisting of hydrogen, fluorine, alkyl, and extraction thereofAny one of a substituent, an alkenyl group and a substituent thereof; in the formulas II, III and IV, X1, X2, X3 and X4 are selected from any one of alkyl, fluorine atom, hydrogen atom, halogenated alkyl, olefin group, alkyne group, aromatic hydrocarbon group and halogenated aromatic hydrocarbon group, and R4 is selected from one of methyl, ethyl, propyl and oxygen atom. Wherein the additive A and the additive B both account for 0.2-3% of the electrolyte by mass.
According to the lithium ion battery electrolyte, the additive A and the additive B are added, so that the triazine ring structure in the additive A is active in nature, and can be oxidized on the surface of the positive electrode preferentially, meanwhile, unsaturated hydrocarbon substances can undergo open-chain polymerization, and the formed film has the characteristics of compactness, solvent resistance and the like, so that the reactivity of the surface of the electrode is reduced, and the oxidative decomposition of the electrolyte at a high temperature is reduced. And the phosphorus-containing additive B can participate in the formation of an SEI film at the negative electrode, and the formed SEI film is rich in P element, has lower interface impedance and is beneficial to the passage of Li ions. The additive A and the additive B are matched for use, so that the thermal stability and the cycle performance of the battery can be improved, the service life of the battery can be prolonged, and the low-temperature performance can be improved.
Specifically, the mass ratio of the additive a in the electrolyte may be 0.2%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 2.8%, 3%. The mass ratio of the additive B in the electrolyte can be 0.2%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 2.8% and 3%.
Specifically, the specific structural formula of the additive a may be any one of the following:
specifically, the specific structural formula of the additive B may be any one of the following:
preferably, additive A is triallyl isocyanurate, which is 1% of the electrolyte mass, and in combination with additive B, the interface resistance, circulation, high temperature storage and low temperature performance are better. Preferably, the additive B is trimethyl phosphate, the trimethyl phosphate accounts for 1% of the electrolyte mass, and the electrolyte is used in combination with the additive A, so that the interface impedance, the circulation, the high-temperature storage and the low-temperature performance are better.
Preferably, the electrolyte further comprises an additive C, wherein the additive C is used as an additive capable of acting on the positive electrode and the negative electrode in a targeted manner and mainly plays roles of film formation of the negative electrode and complexation of the positive electrode. Specifically, the additive C is at least two of Vinylene Carbonate (VC), 1, 3-Propane Sultone (PS), fluoroethylene carbonate (FEC), ethylene sulfate (DTD), succinonitrile (SN), adionitrile (ADN), 1,3, 6-Hexanetrinitrile (HTCN), propylene Sultone (PST), methylene Methane Disulfonate (MMDS) and ethylene glycol bis (propionitrile) ether (EGBE). The additive C accounts for 5-16% of the electrolyte. Specifically, the additive C may be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16% of the electrolyte mass.
Specifically, the concentration of lithium salt in the electrolyte is 0.9M to 2M. For example, 0.9M, 1M, 1.1M, 1.2M, 1.3M, 1.4M, 1.5M, 1.6M, 1.7M, 1.8M, 1.9M, 2M are possible. Preferably, the concentration of lithium salt in the electrolyte is 1.0M to 1.3M. For example, 1M, 1.1M, 1.2M, 1.3M
Specifically, the lithium salt includes lithium hexafluorophosphate (LiPF 6 ) Lithium difluorooxalato borate (LiODFB), lithium difluorodioxaato phosphate (LiDFOP), lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), lithium difluorophosphate (LiPOF) 2 ) At least one of (a) and (b).
Specifically, the solvent includes Ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC), and Propyl Propionate (PP); the mass ratio of EC in the solvent is 10% -30%, the mass ratio of PC in the solvent is 10% -30%, and the mass ratio of DEC in the solvent is 10% -30%; the mass ratio of the PP in the solvent is 30% -60%. Preferably, the mass ratio of EC, PC, DEC, PP is 1:1:1:2.
Specifically, the mass ratio of EC in the solvent may be 10%, 12%, 15%, 17%, 20%, 23%, 25%, 28%, 30%. The mass ratio of PC in the solvent can be 10%, 12%, 15%, 17%, 20%, 23%, 25%, 28%, 30%. The mass ratio of DEC in the solvent may be 10%, 12%, 15%, 17%, 20%, 23%, 25%, 28%, 30%. The mass ratio of PP in the solvent may be 10%, 12%, 15%, 17%, 20%, 23%, 25%, 28%, 30%.
The invention also discloses a lithium ion battery, which comprises a positive plate, a negative plate, a diaphragm and the electrolyte.
Specifically, in the positive plate and the negative plate of the lithium ion battery, the mass ratio of the total content of the P element is not lower than 120ppm.
Specifically, the positive electrode plate comprises a positive electrode current collector and a positive electrode membrane, the negative electrode plate comprises a negative electrode current collector and a negative electrode membrane, the positive electrode membrane comprises a positive electrode active material, a conductive agent and a binder, and the negative electrode membrane comprises a negative electrode active material, a conductive agent and a binder; the positive electrode active material comprises lithium cobaltate, ternary lithium iron phosphate and/or one or more of graphite and/or silicon, the positive electrode active material is preferably lithium cobaltate, and the negative electrode active material is graphite material.
The technical scheme of the present invention is described below by way of specific examples.
Manufacturing of battery
Manufacturing a positive plate: lithium cobalt oxide (LiCoO) as a positive electrode active material 2 ) The conductive agent CNT and the adhesive PVDF are fully stirred and mixed in NMP solvent according to the weight ratio of 97:1.5:1.5, the slurry is coated on an Al foil of the positive current collector, and the positive plate meeting the winding requirement is prepared through the procedures of drying, cold pressing, slitting, tab welding, tab rubberizing and the like.
Manufacturing a negative plate: and (3) fully stirring and mixing the graphite anode serving as an anode active material, the conductive agent SP, the thickening agent CMC and the adhesive SBR in a mass ratio of 96.3:1:1.2:1.5 in a proper amount of deionized water solvent to form uniform anode slurry. The slurry is coated on a Cu foil of a negative current collector, and the negative pole piece meeting the winding requirement is prepared through the procedures of drying, cold pressing, slitting, slice making, tab bonding, and the like
Preparation of electrolyte: the preparation steps of the electrolyte are as follows: EC/PC/DEC/PP was mixed in a mass ratio of 1:1:1:2 as solvent. After mixing evenly, 1.2mol/LLiPF is slowly added 6 Obtaining LiPF 6 Mixed solution with concentration of 1.2mol/L for LiPF 6 After complete dissolution, the electrolyte is obtained by adding the corresponding additive A and additive B.
Wherein, the specific structural formula of the additive A is as follows:
the specific structural formula of the additive B is as follows:
examples 1 to 9 and comparative examples 1 to 5: the electrolytes and the cells to be injected of examples 1 to 9 and comparative examples 1 to 5 were prepared according to the above-described preparation methods, wherein the amounts of additive a and additive B in the electrolytes are shown in table 1 below. 700 baked cells to be injected (moisture less than 120 ppm) are taken, 14 groups of 50 cells are respectively injected with the electrolyte of examples 1-9 and comparative examples 1-5. Then standing, forming, sealing and capacity-dividing detection are carried out according to the normal flow.
The additive a and additive B in the electrolytes of examples 1 to 9 and comparative examples 1 to 5 were added in the following amounts in table 1:
TABLE 1
| Example of the other | Additive A | Additive B |
| Example 1 | 0.2％ | 0.2％ |
| Example 2 | 0.5％ | 0.5％ |
| Example 3 | 0.5％ | 1％ |
| Example 4 | 0.5％ | 2％ |
| Example 5 | 0.5％ | 3％ |
| Example 6 | 0.2％ | 1％ |
| Example 7 | 1％ | 1％ |
| Example 8 | 2％ | 1％ |
| Example 9 | 3％ | 3％ |
| Comparative example 1 | / | / |
| Comparative example 2 | / | 0.5％ |
| Comparative example 3 | 0.5％ | / |
| Comparative example 4 | 5％ | / |
| Comparative example 5 | / | 5％ |
Lithium ion battery performance test
Standing and circulating test at 45 ℃): charging to upper limit voltage at 45deg.C with constant current and constant voltage of 0.7C, cutting off current of 0.05C, standing for 24h, discharging 0.5C to 3.0V, recording discharge energy E0 as initial, repeating for 50 weeks to obtain capacity E50 of 50 weeks, and maintaining energy rate=E50/E0.
And (3) storing at 85 ℃ for 6 hours: charging to upper limit voltage at 25deg.C with constant current and constant voltage of 0.7C, cutting off current of 0.05C, standing for 10min, testing cell thickness H0, storing at 85+ -2deg.C for 6H, and thermally testing thickness H6 to obtain thickness expansion= (H6-H0)/H0.
-10 ℃ discharge: full at 25 ℃ with 0.7C, off-current 0.05C, rest for 10min, 0.2C discharge to 3.0V at 25 ℃, record discharge capacity C0, full at 25 ℃ with 0.7C, off-current 0.05C, rest for 2H at-10 ℃, then discharge to 3.4V with 0.2C, record discharge capacity C1,3.4V capacity retention = C1/C0.
The results of examples 1 to 9 and comparative examples 1 to 5 are shown in Table 2 below:
TABLE 2
The test results of comparative examples 1-3 show that the additive A is added, and the standing circulation and the high-temperature storage of the battery cell at 45 ℃ are improved; the addition of the additive B obviously improves the low-temperature discharge. Examples 1 to 9, additive a and additive B simultaneously, improved standing cycle, high temperature storage, and low temperature discharge. In comparative examples 4 to 5, when the additive A was added in an amount of 5%, the additive A deteriorated the low-temperature discharge, and the additive B improved the low-temperature discharge because the interface resistance was increased and the discharge electrode was excessively polarized due to the excessive content of the additive A.
In comparative examples 1 to 9 and comparative example 1, the high-temperature cycle performance was improved first and then slightly deteriorated as the amount of the additive A added was increased, and the low-temperature discharge was improved by the addition of the additive B, wherein the improvement by 0.2% was not significant, the improvement by 1% was more significant, and the improvement effect was not significant by the subsequent increase in the amount.
The comprehensive effect of the embodiment 7 is optimal, and the proper addition amount of the additive A and the additive B has a synergistic effect, so that the film has stronger mechanical property and toughness, and meanwhile, the film forming resistance of the additive B is lower. Therefore, proper amounts of the additive A and the additive B are added, and through the synergistic effect of the additive A and the additive B, the standing circulation, high-temperature storage and low-temperature performance of the battery cell at 45 ℃ can be improved.
The above description of the invention in connection with specific alternative embodiments is further detailed and it is not intended that the invention 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 invention, and these should be considered to be within the scope of the invention.
Claims (10)
1. The lithium ion battery electrolyte is characterized by comprising lithium salt, a solvent and an additive, wherein the additive comprises an additive A and a phosphorus-containing additive B; the general formula of the additive A is shown in the following formula I:
the general formula of the additive B is shown in the following formulas II, III and IV:
in the formula I, R 1 ～R 3 Each independently selected from any one of a hydrogen atom, a fluorine atom, an alkyl group and a substituent thereof, an alkenyl group and a substituent thereof; in the formulas II, III and IV, X1, X2, X3 and X4 are selected from any one of alkyl, fluorine atom, hydrogen atom, halogenated alkyl, olefin, alkyne, aromatic alkyl and halogenated aromatic alkyl, R 4 One selected from methyl, ethyl, propyl and oxygen atoms;
wherein the additive A and the additive B both account for 0.2-3% of the electrolyte by mass.
2. The lithium ion battery electrolyte according to claim 1, wherein the additive a is triallyl isocyanurate, and the triallyl isocyanurate accounts for 1% of the mass of the electrolyte.
3. The lithium ion battery electrolyte according to claim 2, wherein the additive B is trimethyl phosphate, and the trimethyl phosphate accounts for 1% of the mass of the electrolyte.
4. The lithium-ion battery electrolyte of claim 1, wherein the concentration of lithium salt in the electrolyte is between 0.9M and 2M.
5. The lithium ion battery electrolyte of claim 4, wherein the concentration of lithium salt in the electrolyte is 1.0M to 1.3M.
6. The lithium-ion battery electrolyte of claim 1, wherein the lithium salt comprises lithium hexafluorophosphate (LiPF 6 ) Lithium difluorooxalato borate (LiODFB), lithium difluorodioxaato phosphate (LiDFOP), lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), lithium difluorophosphate (LiPOF) 2 ) At least one of (a) and (b).
7. The lithium-ion battery electrolyte of claim 1, wherein the solvent comprises EC, PC, DEC and PP; the mass ratio of the EC in the solvent is 10-30%, the mass ratio of the PC in the solvent is 10-30%, and the mass ratio of the DEC in the solvent is 10-30%; the mass ratio of the PP in the solvent is 30% -60%.
8. A lithium ion battery comprising a positive plate, a negative plate, a separator and the electrolyte according to any one of claims 1 to 7.
9. The lithium ion battery according to claim 8, wherein a mass ratio of a total content of P element in the positive electrode sheet and the negative electrode sheet of the lithium ion battery is not less than 120ppm.
10. The lithium ion battery of claim 8, wherein the positive electrode tab comprises a positive electrode current collector and a positive electrode membrane, the negative electrode tab comprises a negative electrode current collector and a negative electrode membrane, the positive electrode membrane comprises a positive electrode active material, a conductive agent, and a binder, and the negative electrode membrane comprises a negative electrode active material, a conductive agent, and a binder; the positive electrode active material comprises lithium cobaltate, ternary lithium iron phosphate and/or one or more of graphite and/or silicon, the positive electrode active material is preferably lithium cobaltate, and the negative electrode active material is graphite material.
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