CN113540565B - Flame-retardant lithium ion battery electrolyte and preparation method thereof - Google Patents
Flame-retardant lithium ion battery electrolyte and preparation method thereof Download PDFInfo
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- CN113540565B CN113540565B CN202110297545.3A CN202110297545A CN113540565B CN 113540565 B CN113540565 B CN 113540565B CN 202110297545 A CN202110297545 A CN 202110297545A CN 113540565 B CN113540565 B CN 113540565B
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 104
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 title claims abstract description 72
- 239000003063 flame retardant Substances 0.000 title claims abstract description 72
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 60
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 59
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- 239000000654 additive Substances 0.000 claims abstract description 58
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 53
- 239000010452 phosphate Substances 0.000 claims abstract description 52
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 44
- 230000000996 additive effect Effects 0.000 claims abstract description 42
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910052796 boron Inorganic materials 0.000 claims abstract description 36
- 239000013538 functional additive Substances 0.000 claims abstract description 36
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 22
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 22
- 239000003960 organic solvent Substances 0.000 claims abstract description 17
- 150000001875 compounds Chemical class 0.000 claims abstract description 13
- XGCTUKUCGUNZDN-UHFFFAOYSA-N [B].O=O Chemical compound [B].O=O XGCTUKUCGUNZDN-UHFFFAOYSA-N 0.000 claims abstract description 5
- -1 cyano, sulfonyl Chemical group 0.000 claims description 22
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 18
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 15
- 229910052744 lithium Inorganic materials 0.000 claims description 15
- 239000002904 solvent Substances 0.000 claims description 13
- 125000001424 substituent group Chemical group 0.000 claims description 9
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 claims description 8
- 239000011737 fluorine Substances 0.000 claims description 8
- 229910052731 fluorine Inorganic materials 0.000 claims description 8
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 claims description 8
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 7
- 125000004432 carbon atom Chemical group C* 0.000 claims description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 5
- ORNGPPZBMMHKPM-UHFFFAOYSA-N 1,1,1,2,2-pentafluoro-2-(1,1,2,2,2-pentafluoroethoxy)ethane Chemical compound FC(F)(F)C(F)(F)OC(F)(F)C(F)(F)F ORNGPPZBMMHKPM-UHFFFAOYSA-N 0.000 claims description 4
- VDFVNEFVBPFDSB-UHFFFAOYSA-N 1,3-dioxane Chemical compound C1COCOC1 VDFVNEFVBPFDSB-UHFFFAOYSA-N 0.000 claims description 4
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 claims description 4
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 claims description 4
- 125000003342 alkenyl group Chemical group 0.000 claims description 4
- 125000000217 alkyl group Chemical group 0.000 claims description 4
- 125000000304 alkynyl group Chemical group 0.000 claims description 4
- 125000003277 amino group Chemical group 0.000 claims description 4
- 125000003118 aryl group Chemical group 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 150000005678 chain carbonates Chemical class 0.000 claims description 4
- 125000004093 cyano group Chemical group *C#N 0.000 claims description 4
- 150000005676 cyclic carbonates Chemical class 0.000 claims description 4
- 125000001153 fluoro group Chemical group F* 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims description 4
- 150000003949 imides Chemical class 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims description 4
- 125000000472 sulfonyl group Chemical group *S(*)(=O)=O 0.000 claims description 4
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 3
- CHHOPPGAFVFXFS-UHFFFAOYSA-M [Li+].[O-]S(F)(=O)=O Chemical compound [Li+].[O-]S(F)(=O)=O CHHOPPGAFVFXFS-UHFFFAOYSA-M 0.000 claims description 3
- 239000003660 carbonate based solvent Substances 0.000 claims description 3
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 3
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 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
- MCVFFRWZNYZUIJ-UHFFFAOYSA-M lithium;trifluoromethanesulfonate Chemical compound [Li+].[O-]S(=O)(=O)C(F)(F)F MCVFFRWZNYZUIJ-UHFFFAOYSA-M 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 2
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 2
- 125000001931 aliphatic group Chemical group 0.000 claims description 2
- 239000004327 boric acid Substances 0.000 claims description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 claims description 2
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims description 2
- NKDDWNXOKDWJAK-UHFFFAOYSA-N dimethoxymethane Chemical compound COCOC NKDDWNXOKDWJAK-UHFFFAOYSA-N 0.000 claims description 2
- 229910001486 lithium perchlorate Inorganic materials 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 2
- 229920001774 Perfluoroether Polymers 0.000 claims 1
- 239000004210 ether based solvent Substances 0.000 claims 1
- UJMWVICAENGCRF-UHFFFAOYSA-N oxygen difluoride Chemical compound FOF UJMWVICAENGCRF-UHFFFAOYSA-N 0.000 claims 1
- 125000002467 phosphate group Chemical group [H]OP(=O)(O[H])O[*] 0.000 claims 1
- 230000002195 synergetic effect Effects 0.000 abstract description 4
- 150000001642 boronic acid derivatives Chemical class 0.000 abstract description 2
- 235000021317 phosphate Nutrition 0.000 description 42
- 230000000052 comparative effect Effects 0.000 description 14
- 230000000694 effects Effects 0.000 description 14
- 229920000742 Cotton Polymers 0.000 description 7
- 239000003365 glass fiber Substances 0.000 description 7
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 7
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 7
- 239000003153 chemical reaction reagent Substances 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 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 description 5
- 230000002829 reductive effect Effects 0.000 description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 239000012300 argon atmosphere Substances 0.000 description 4
- 239000011267 electrode slurry Substances 0.000 description 4
- 239000008151 electrolyte solution Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 239000011574 phosphorus Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000013112 stability test Methods 0.000 description 3
- WVLBCYQITXONBZ-UHFFFAOYSA-N trimethyl phosphate Chemical compound COP(=O)(OC)OC WVLBCYQITXONBZ-UHFFFAOYSA-N 0.000 description 3
- WBRSYBLNSTYNPP-UHFFFAOYSA-N 2,4,6-tris(ethenyl)-1,3,5,2,4,6-trioxatriborinane Chemical compound C=CB1OB(C=C)OB(C=C)O1 WBRSYBLNSTYNPP-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- YJTKZCDBKVTVBY-UHFFFAOYSA-N 1,3-Diphenylbenzene Chemical group C1=CC=CC=C1C1=CC=CC(C=2C=CC=CC=2)=C1 YJTKZCDBKVTVBY-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000662429 Fenerbahce Species 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- HYTUWJOIMIPIGK-UHFFFAOYSA-N [O].C(C)B(CC)CC Chemical compound [O].C(C)B(CC)CC HYTUWJOIMIPIGK-UHFFFAOYSA-N 0.000 description 1
- UIBSFHCPFRDYMD-UHFFFAOYSA-N [O].C1(=CC=CC=C1)B(C1=CC=CC=C1)C1=CC=CC=C1 Chemical compound [O].C1(=CC=CC=C1)B(C1=CC=CC=C1)C1=CC=CC=C1 UIBSFHCPFRDYMD-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000011255 nonaqueous electrolyte Substances 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 description 1
- 238000005303 weighing 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
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- 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
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- 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 a flame-retardant lithium ion battery electrolyte and a preparation method thereof, wherein the electrolyte comprises an organic solvent, lithium salt and an additive, and is characterized in that the additive comprises a phosphate additive and a boron-containing functional additive, the phosphate additive is selected from a compound shown in the following general formula (1), and the boron-containing functional additive comprises unsaturated borate and/or boron-oxygen hexacyclic ring. According to the flame-retardant lithium ion battery electrolyte, the phosphate additive with a specific structure and the boron-containing functional additive are contained, the content ratio of the phosphate additive and the boron-containing functional additive is precisely set, and the synergistic effect of the two additives is exerted, so that the flame retardance and the charge and discharge performance can be improved simultaneously.
Description
Technical Field
The invention relates to the field of electrolytes for lithium ion batteries, in particular to a flame-retardant lithium ion battery electrolyte and a preparation method thereof.
Background
With the continuous development of new energy technology, the market of portable electronic devices and electric vehicles is growing, and the worldwide demand for new energy is increasing. Lithium ion batteries have replaced traditional batteries and have been widely used in the field of new energy sources due to their advantages of high energy density, excellent cycle performance, low self-discharge rate, etc.
However, the electrolyte used in the lithium ion battery contains a large amount of organic solvents with low flash points, and when the lithium ion battery is charged or heated, the electrolyte in the battery can undergo irreversible redox decomposition to generate combustible gas, so that the internal pressure and temperature of a battery system can be increased rapidly to cause safety accidents, and therefore, a flame retardant additive needs to be added into the electrolyte to reduce the flammability of the electrolyte of the lithium ion battery and improve the safety performance of the lithium ion battery.
In order to solve the above-mentioned safety problems, it is disclosed in Japanese patent applications JP2000-235867 and JP 2002-280061 that flame retardancy is achieved by using an organic phosphate compound such as trimethyl phosphate or triethyl phosphate as an additive or co-solvent. However, when the organic phosphate compound is applied to an electrolyte of a lithium ion battery, the conductivity is lowered, and the organic phosphate compound is reduced and decomposed on the surface of a graphite negative electrode, thereby inhibiting the charge and discharge performance of the battery.
Patent application CN110590848 discloses a five-membered ring phosphate which has flame retardancy and film forming functions of positive and negative electrodes, but when used alone, is often greatly influenced by the addition amount, greatly influencing the charge and discharge performance.
In general, in order to maintain the normal charge and discharge function of the battery, it is necessary to mix it with a carbonate-based flammable solvent, and in this case, the content of the organic phosphate compound in the mixed solvent is generally reduced, resulting in a reduction in the flame retardant property.
In view of the above, in order to achieve both the flame retardant safety performance and the charge and discharge performance of the battery, it is urgently required to develop an electrolyte solution that can exhibit excellent flame retardant properties and thermal stability without affecting electrochemical properties such as the charge and discharge performance.
Disclosure of Invention
The invention aims to provide a flame-retardant lithium ion battery electrolyte and a preparation method thereof.
The purpose of the invention can be realized by the following technical scheme:
[1] the flame-retardant lithium ion battery electrolyte comprises an organic solvent, a lithium salt and additives, wherein the additives comprise phosphate additives and boron-containing functional additives, and the phosphate additives are selected from compounds shown in the following general formula (1):
wherein n is an integer of 1 to 5, preferably an integer of 1 to 3, the ring may or may not have a double bond, and the substituent R1 on the ring is selected from hydrogen, fluorine, an isocyanate group, a cyano group, a sulfonyl group, a carbonyl group or an amino group,
x is selected from lithium ion, substituted or unsubstituted straight-chain or branched-chain alkyl, aryl, alkenyl or alkynyl with 1-8 carbon atoms, and the substituent is selected from fluorine, isocyanate group, cyano, sulfonyl, carbonyl or amino.
[2] The flame-retardant lithium ion battery electrolyte according to [1], wherein the total mass of the electrolyte is 100%,
the mass of the organic solvent is 28.5-89.5%, preferably 47.8-82.6%,
the mass of the lithium salt is 5.0-30.0%, preferably 10.0-25.0%;
the phosphate additive is 5.0 to 50.0% by mass, preferably 5.0 to 40.4% by mass, more preferably 10.0 to 30.0% by mass,
the mass of the boron-containing functional additive is 0.5-2.0%.
[3] The flame-retardant lithium ion battery electrolyte according to [1] or [2], wherein the phosphate additive comprises at least 1 of compounds represented by structural formulas I to X:
[4] the flame-retardant lithium ion battery electrolyte according to [1] or [2],
the compound represented by the general formula (1) is a phosphate additive having a four-membered ring represented by the following general formula (2):
wherein, the quaternary ring in the general formula (2) may or may not have double bonds, R1 is selected from hydrogen, fluorine, isocyanate group, cyano group, sulfonyl group, carbonyl group or amino group,
x is selected from lithium ion, substituted or unsubstituted straight chain or branched chain alkyl, aryl, alkenyl or alkynyl with 1-8 carbon atoms, and the substituent is selected from fluorine, isocyanate group, cyano, sulfonyl, carbonyl or amino.
[5] According to the flame-retardant lithium ion battery electrolyte of 4,
the phosphate ester additive with four-membered rings is a compound shown in structural formulas I to IV
[6] The flame-retardant lithium ion battery electrolyte according to the [1] or [2], wherein the boron-containing functional additive comprises unsaturated boric acid ester and/or boron-oxygen hexacyclic ring,
the unsaturated borate comprises a tributyleneborate and/or a trivinylborate,
the boron-oxygen-six ring comprises one or more than two of trivinyl boron-oxygen-six ring, triethyl boron-oxygen-six ring and triphenyl boron-oxygen-six ring,
the boron-containing functional additive is preferably trivinylboroxine or tributenyl borate, and more preferably trivinylboroxine.
[7] The flame-retardant lithium ion battery electrolyte according to [1] or [2], wherein the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis (oxalato) phosphate, lithium difluorooxalato borate, lithium bis (oxalato) borate, lithium bis (fluorosulfonato) imide, lithium bis (trifluoromethanesulfonyl) imide, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium fluorosulfonate and lithium perchlorate, and preferably comprises lithium bis (fluorosulfonato) imide and/or lithium bis (trifluoromethanesulfonyl) imide.
[8] The flame-retardant lithium ion battery electrolyte according to [1] or [2], wherein the organic solvent comprises a carbonate solvent and/or an ether solvent,
the carbonate-based solvent contains a cyclic carbonate and/or a chain carbonate,
the cyclic carbonate contains one or more of vinylene carbonate, fluoroethylene carbonate, ethylene carbonate, propylene carbonate and gamma-butyrolactone;
the chain carbonate comprises one or more than two of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, linear chain or branched chain aliphatic mono-alcohol with 3-8 carbon atoms and carbonate synthesized by carbonic acid;
the ether solvent contains one or more of 1, 3-dioxane, dimethoxymethane, diglyme, perfluoroethyl ether, C4-10 linear or branched monobasic ether and C4-10 linear or branched polybasic ether, preferably 1, 3-dioxane and perfluoroethyl ether.
[9] A lithium ion battery comprises a positive pole piece, a negative pole piece, electrolyte and a diaphragm, wherein the electrolyte is the flame-retardant lithium ion battery electrolyte in any one of the following items [1] to [8 ].
[10] The preparation method of the flame-retardant lithium ion battery electrolyte is any one of 1-8, and comprises the following steps:
adding 5.0-30.0 parts by mass of lithium salt into 28.5-89.5 parts of organic solvent with the water content of less than 20ppm and the oxygen content of less than 1ppm in a glove box, stirring and dissolving, adding 5.0-50.0 parts of phosphate flame-retardant additive and 0.5-2.0 parts of boron-containing functional additive after the lithium salt is completely dissolved, and completely mixing the materials to obtain the flame-retardant lithium ion battery electrolyte.
The invention has the following beneficial effects:
the invention provides a flame-retardant lithium ion battery electrolyte, which comprises an organic solvent, lithium salt, phosphate additives and boron-containing functional additives in a specific content ratio. Research shows that the redox decomposition degree of the electrolyte on the surfaces of the positive and negative electrodes is related to the contact area between the electrolyte and the electrode plate. According to the invention, the phosphate additive with a specific structure and the boron-containing functional additive with a specific structure are added into the electrolyte in a combined manner, so that the synergistic effect of the phosphate additive and the boron-containing functional additive can be fully exerted, the phosphate additive has excellent flame retardant effect and thermal stability, and has a cyclic structure and other functional groups, so that a Solid Electrolyte Interface (SEI) film can be formed, the boron-containing functional additive has low impedance, the cycle performance at high temperature can be improved, and the SEI film can be formed on the surface of a positive electrode material and a negative electrode material preferentially, so that the redox decomposition reaction of the electrolyte on the surfaces of the positive electrode and the negative electrode can be inhibited, and the electrochemical stability can be improved. Therefore, the electrolyte has excellent flame retardant property and thermal stability, and has excellent electrochemical properties such as charge and discharge performance.
Detailed Description
In the present specification, unless otherwise specified, the following meanings are given to the symbols, units, abbreviations and terms.
In the present specification, when numerical ranges are expressed using "or", they include both endpoints, and the units are common. For example, 5 to 25% means 5% or more and 25% or less.
Hereinafter, the flame-retardant lithium ion battery electrolyte and the preparation method thereof according to the present invention will be described in detail based on preferred embodiments.
The invention discloses a flame-retardant lithium ion battery electrolyte, which comprises an organic solvent, lithium salt and additives, wherein the additives comprise phosphate additives and boron-containing functional additives, and the phosphate additives are selected from compounds shown in the following general formula (1):
wherein n is an integer of 1 to 5, the ring may or may not have a double bond, and the substituent R1 on the ring is selected from hydrogen, fluorine, an isocyanate group, a cyano group, a sulfonyl group, a carbonyl group or an amino group,
x is selected from lithium ion, substituted or unsubstituted straight-chain or branched-chain alkyl, aryl, alkenyl or alkynyl with 1-8 carbon atoms, and the substituent is selected from fluorine, isocyanate group, cyano, sulfonyl, carbonyl or amino.
In the flame-retardant lithium ion battery electrolyte, based on 100% of the total mass of the electrolyte,
the mass of the organic solvent is 28.5-89.5%, preferably 47.8-82.6%,
the mass of the lithium salt is 5.0-30.0%, preferably 10-25%;
the phosphate additive is 5.0 to 50.0% by mass, preferably 5.0 to 40.4% by mass, more preferably 10.0 to 30.0% by mass,
the mass of the boron-containing functional additive is 0.5-2.0%.
In some embodiments, the lithium salt in the flame-retardant lithium ion battery electrolyte of the present invention comprises one or more of the following compounds: lithium hexafluorophosphate (LiPF 6), lithium difluorophosphate (LiPF 2O 2), lithium difluorobis (oxalato) phosphate (LiODFP), lithium difluorooxalato borate (LiODFB), lithium bis (oxalato) borate (LiBOB), lithium bis (fluorosulfonyl) imide (LiFSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium tetrafluoroborate (LiBF 4), lithium trifluoromethanesulfonate (LiSO 3 CF 3), lithium fluorosulfonate (LiSO 3F) and lithium perchlorate (LiClO 4). Among them, it is preferable to contain LiFSI and/or LiTFSI in view of excellent charge and discharge characteristics of the battery.
The addition amount of the lithium salt in the electrolyte is 5.0-30.0% based on 100% of the total mass of the electrolyte, and when the addition amount of the lithium salt is less than 5 parts or more than 30 parts, the conductivity of the electrolyte solution is reduced at a high charge-discharge rate, which causes deterioration of charge-discharge characteristics of the lithium ion battery. From the viewpoint of obtaining more excellent charge/discharge performance, it is preferably 10.0 to 25.0%.
The amount of the phosphate flame retardant additive added is, for example, 5.0 to 50.0%, preferably 5.0 to 40.4%, and more preferably 10.0 to 30.0% based on 100% by mass of the total electrolyte. When the addition amount of the phosphate flame-retardant additive is less than 5.0%, the flame-retardant effect of the flame-retardant additive cannot be effectively exerted, and when the addition amount is more than 50.0%, the conductivity of an electrolyte system is reduced, so that the charge and discharge characteristics of a battery system are influenced.
The boron-containing functional additive adopted by the invention contains unsaturated boric acid ester and/or boron-oxygen hexacyclic compound, such as one or more of tributylene boric acid ester, trivinyl boron-oxygen hexacyclic compound, triethyl boron-oxygen hexacyclic compound, triphenyl boron-oxygen hexacyclic compound, etc., which can form SEI film on positive and negative electrodes, protect positive and negative electrodes, and inhibit redox of electrolyte on the surfaces of the positive and negative electrodes. The addition amount of the boron-containing functional additive is 0.5-2.0 wt%, preferably 1.0-1.5 wt% based on 100% of the total mass of the electrolyte. When the addition amount of the boron-containing functional additive is less than 0.5%, the boron-containing functional additive is difficult to form a film on the positive electrode and the negative electrode in advance, so that the redox decomposition reaction of the electrolyte on the surfaces of the positive electrode and the negative electrode cannot be effectively inhibited, and when the addition amount is more than 2.0%, the film is thicker on the positive electrode and the negative electrode, so that the charge and discharge performance of a battery system is adversely affected.
The solvent used in the present invention includes a carbonate solvent and/or an ether solvent, and is a solvent commonly used in an electrolytic solution, and the internal compounding ratio thereof is not particularly limited as long as a predetermined effect can be obtained.
The compound represented by the above general formula (1) is preferably a phosphate additive having a four-membered ring represented by the following general formula (2):
the phosphate ester additive with a four-membered ring has higher phosphorus content and relatively better flame retardant effect, and is preferred.
The present invention will be described in more detail with reference to examples and comparative examples, but the technical scope of the present invention is not limited to these examples. All percentages, parts and ratios used in the present invention are based on mass unless otherwise specified.
The raw materials or reagents used in the present invention are all purchased from mainstream manufacturers in the market, and those without reference to manufacturers or concentrations are all analytical pure grade raw materials or reagents that can be obtained conventionally, and are not particularly limited as long as they can perform the intended function. The instruments and devices used in the present example, such as a glove box, a moisture tester, a potentiometric titrator, a conductivity meter, and a stirrer, are purchased from major manufacturers in the market, and are not particularly limited as long as they can perform the intended functions. The specific techniques or conditions not specified in this example were performed according to the techniques or conditions described in the literature in the art or according to the product specification.
The raw materials and instruments used in the examples and comparative examples were as follows:
glove box, available from Shanghai Mi Karana electro-mechanical technology, inc.;
organic solvents, available from hadamard (Adamas);
lithium salts, purchased from Korea Tianbao industry co., aladdin chemical reagent net;
phosphate additives, available from Shanghai Yixie chemical industry Co., ltd., allantin chemical reagent net, national medicine reagent net;
boron-containing functional additives purchased from aladine chemical reagent net.
Example 1
In an argon atmosphere glove box with the moisture content of less than 1ppm and the oxygen content of less than 1ppm, EC 39.3g and DMC 30.0g (the sum of the mass fractions of the solvents is 69.3%) with the moisture contents of 9ppm and 6ppm, respectively, are added into a 250mL beaker washed and dried in advance at 25 ℃, then 7.6g of lithium bis (fluorosulfonyl) imide (7.6%) and 7.0g of lithium bis (trifluoromethanesulfonyl) imide (7.0%) are added, and the mixture is stirred for 30min with a stirrer at 400rpm and dissolved uniformly, and then 2,4, 6-trivinylboroxine (1.0%) with the mass of 1.0g and 15.0g of 2- (2, 2-trifluoroethoxy) -1,3, 2-dioxaphosphorinanolide phosphate (structural formula I) (15.0%) are added thereto to prepare the flame-retardant lithium ion battery electrolyte of example 1.
The moisture content in the electrolyte was measured to be 18ppm by a moisture meter (Switzerland 917) and the acid value in the electrolyte was measured to be 56ppm (free acid) by a potentiometric titrator (Switzerland 916).
The internal mixing ratio of the organic solvent used in the present invention is not particularly limited, and the moisture content thereof is very low as long as a predetermined effect can be obtained, and the moisture content and the acid value of the flame-retardant lithium ion battery electrolyte prepared in an argon atmosphere glove box having a moisture content of less than 1ppm are both 50ppm or less and 100ppm or less, which all meet the electrolyte use standard. The prepared flame-retardant lithium ion battery electrolyte is subjected to the following flame retardance test, charge and discharge performance test and stability test.
Examples 2 to 17
Lithium ion battery electrolytes of examples 2 to 17 were obtained in the same manner as in example 1 except that the types and contents of the solvent, lithium salt, phosphate flame retardant additive and boron-containing functional additive were changed as shown in table 1.
Comparative example 1
In an argon atmosphere glove box with a moisture content of <1ppm and an oxygen content of <1ppm, EC 48.2g and EMC 36.2g with moisture contents of 9ppm and 6ppm, respectively, were added to a 250mL beaker washed and dried in advance at 25 ℃, 7.6g of lithium bis (fluorosulfonyl) imide (7.6%, 0.6 mol/L) and 7.0g of lithium bis (trifluoromethanesulfonyl) imide (7.0%, 0.8 mol/L) were added in two portions, and after uniform dissolution with stirring in a 400rpm stirrer, 2,4, 6-trivinyloxybenzone (1%) with a mass of 1.0g was added thereto to prepare the electrolyte for a lithium ion battery of comparative example 1.
The moisture content in the electrolyte was measured to be 15ppm by a moisture tester (switzerland wantong 917), and the acid value in the electrolyte was measured to be 36ppm by a potentiometric titrator (switzerland wantong 916), and the following flame retardancy test, charge and discharge performance test, and stability test were performed.
Comparative examples 2 to 6
The procedure of example 1 was repeated, except that the components and the amounts shown in Table 1 were mixed uniformly.
TABLE 1
In Table 1, TVBO is 2,4, 6-trivinylboroxine, TBB is tributenylborate, EC is ethylene carbonate, DMC is dimethyl carbonate, EMC is ethyl methyl carbonate, and PFEE is perfluoroethyl ether.
The electrolytes in the above examples and comparative examples were subjected to the following tests.
(1) Conductivity test
30mL of the prepared electrolyte was measured for conductivity at 25 ℃ using a conductivity Meter (Switzerland 914 PH Meter/conductor Meter).
(2) Flame retardancy test
A glass fiber cotton sliver prepared in advance and having the length of 300mm and the diameter of 2mm is placed in a flask containing the electrolyte of the embodiment and the comparative example to be soaked for 12 hours, and after the electrolyte is sufficiently absorbed, the excess electrolyte on the glass fiber cotton is removed by using the edge of the flask. And weighing the weight of the glass fiber cotton sliver before and after soaking to obtain the mass of the electrolyte absorbed by the glass fiber cotton sliver. Clamping the glass fiber cotton by using tweezers, burning the lower end of the glass fiber cotton for 3 seconds by using an igniter, removing a fire source after the glass fiber cotton is burnt, starting timing until the flame is extinguished, and stopping timing so as to measure the self-extinguishing time of the burning, carrying out parallel measurement for at least 5 times, and taking the average value. This combustion self-extinguishing time is converted to a combustion self-extinguishing time per gram of electrolyte. And judging the flame retardant property of the electrolyte according to the combustion self-extinguishing time of the electrolyte per unit mass.
(3) Discharge capacity test
Natural graphite and a polyvinylidene fluoride resin as a binder were mixed at a mass ratio of 90: 10, dispersed in an N-methylpyrrolidone solvent to form a negative electrode slurry, and the negative electrode slurry was coated on both sides of a copper foil and dried to obtain a negative electrode sheet. The negative electrode sheet was cut into a width of 20mm and a length of 150mm to serve as a negative electrode. Lithium cobalt oxide (LiCoO 2), acetylene black, and a polyvinylidene fluoride resin were mixed at a weight ratio of 90: 5, and dispersed in N-methylpyrrolidone to form a positive electrode slurry, and the positive electrode slurry was coated on both surfaces of an aluminum foil as a positive electrode current collector and dried to obtain a positive electrode sheet. The positive electrode sheet was cut into a width of 20mm and a length of 150mm to obtain a positive electrode. The negative electrode and the positive electrode thus produced were each provided with a tab, and a porous polypropylene film having a width of 25mm and a length of 200mm was wound to produce a cell. The cell is put into a closed battery shell in a dry argon environment, and the lithium ion battery electrolyte prepared in the embodiment and the comparative example of the invention is injected to prepare the lithium ion secondary battery. The charge/discharge characteristics of the battery were evaluated while maintaining the airtightness of the battery.
At 25 ℃, the prepared lithium ion secondary battery is charged to 4.2V at constant current and constant voltage of 50mA, the current is cut off and 0.02C is kept for 5min, and when the battery is discharged to the voltage of 2.5V at constant current of 10mA, the battery is kept for 5min, and the discharge capacity of the battery after the first circulation at 25 ℃ is recorded. And thirdly, stopping charging to 4.2V at a constant current and a constant voltage of 50mA, stopping the current at 0.02C, standing for 5min, discharging at a constant current of 10mA until the voltage is 2.5V, standing for 5min, circulating according to the above steps, and recording the discharge capacity after 100 cycles of charging and discharging.
(4) Thermal stability test
The lithium ion secondary battery prepared as described above was charged and discharged for 2 cycles under the above conditions, charged to a voltage of 4.2V, kept in a fully charged state, charged in a predetermined high-pressure sealed container (withstand voltage 105 × 10 Pa) in a dry argon atmosphere, heated at a temperature rise rate of 1 ℃ per minute in a range of 25 to 300 ℃ by an adiabatic acceleration calorimeter ARC 254 (german relaxation resistance), and the heat generation rate and the pressure rise rate in the thermal decomposition process of the battery at that time were measured, thereby evaluating the thermal stability (thermal decomposition rate) of the battery.
TABLE 2
In Table 2, the self-extinguishing time is 0s, indicating that the electrolyte is nonflammable.
As can be seen from tables 1 and 2, in the electrolytes of examples 1 to 17, the phosphorus-containing flame retardant additive and the boron-containing functional additive according to the present invention are included in a specific range, and the synergistic effect of the two additives is utilized, so that the excellent flame retardant effect can be exerted while the electrical conductivity is ensured, the internal heat generation of the battery is significantly suppressed, the pressure rise rate in the battery is slowed, the good thermal stability is exhibited, the safety performance of the battery is ensured, and simultaneously, the SEI film is favorably formed on the positive and negative electrode materials, and the electrochemical properties such as the discharge capacity of the battery are improved. Moreover, the flame retardant composition can exert good electrochemical performance even when the content of the phosphate additive is high (the mass fraction is 50%), can exert excellent flame retardant property and thermal stability even when the content of the phosphate additive is low (the mass fraction is 5%), can expand the application range of the phosphate additive, and can achieve both flame retardancy and electrochemical performance.
Further, the phosphorus-containing flame retardant additives represented by the general formulae I to IV are phosphate additives having four-membered rings, and are relatively excellent in overall properties in terms of flame retardant effect, electrochemical properties, etc., probably because these phosphate compounds having four-membered rings have a relatively high phosphorus-containing ratio and high flame retardancy, and in addition, have substituents that facilitate the formation of an SEI film to improve electrochemical properties. In particular, in the electrolytes of examples 15 to 17, the two types of four-membered ring phosphates having different substituents were combined, and therefore, the electrolytes were more excellent in the overall properties such as conductivity, flame retardant effect, and electrochemical properties.
As can be seen from tables 1 and 2, the electrolyte of comparative example 1 contains boron functional additives, but does not contain phosphate flame retardant additives, so the electrolyte has no flame retardant effect, and has a serious potential safety hazard because the heating speed and the pressure rise speed are remarkably increased in a full-charge state.
As is apparent from tables 1 and 2, the electrolyte of comparative example 2, which contains a boron-containing functional additive and trimethyl phosphate, has a flame retardant effect but poor discharge performance, and may be caused by the fact that trimethyl phosphate is easily intercalated into a graphite negative electrode material to cause a loss in discharge capacity, and does not have a film-forming function like a cyclic phosphate ester, has a certain volatility, and adversely affects the electrochemical performance of a battery.
As is apparent from tables 1 and 2, the electrolyte of comparative example 3 contains a phosphate flame retardant additive, but does not contain a boron-containing functional additive, and the electrolyte is not easily inhibited from redox decomposition on the surfaces of the positive and negative electrodes, and the battery discharge capacity performance is deteriorated.
As can be seen from tables 1 and 2, the electrolyte of the comparative example 4 does not contain the phosphate flame retardant additive and the boron-containing functional additive, and the electrolyte does not have a flame retardant effect, so that the heating speed and the pressure rise speed of the electrolyte are obviously increased in a full-electricity state, and serious potential safety hazards exist.
As can be seen from tables 1 and 2, the discharge performance is seriously reduced when the addition amount of the phosphate flame retardant additive in the electrolyte of the comparative example 5 is too large to exceed the range of the present invention, and the reason may be that the excessive addition of the flame retardant additive may reduce the system conductivity and have a great negative effect on the charge and discharge performance of the battery.
As can be seen from tables 1 and 2, when the amount of the boron-containing functional additive added to the electrolyte of comparative example 6 is outside the range of the present invention, the discharge performance is rather decreased, which may be caused by the negative effect of the boron-containing functional additive on the charge/discharge performance of the battery due to the thick film formed on the positive and negative electrodes.
The nonaqueous electrolytic solution of the present invention contains an organic solvent, a lithium salt, a phosphate additive having a specific structure and a boron-containing functional additive having a specific structure at a specific ratio, and thereby can sufficiently exhibit the synergistic effect of the phosphate additive and the boron-containing functional additive. The phosphate additive has a cyclic structure and other functional groups or Li ions, has excellent flame retardant effect and thermal stability, and particularly has relatively better flame retardant comprehensive performance of the phosphate additive with a four-membered ring, thereby being beneficial to forming an SEI film. The boron-containing functional additive has low impedance, can improve discharge capacity and cycle performance at high temperature, and can form an SEI film on the surfaces of the positive and negative electrode materials preferentially, so that redox decomposition reaction of the electrolyte on the surfaces of the positive and negative electrodes is inhibited, and electrochemical stability is improved. Therefore, the non-aqueous electrolyte provided by the invention has excellent flame retardant property and thermal stability, and can improve the charge and discharge performance and cycle performance of the battery.
The above description is only for the purpose of illustrating the present invention, but not for the purpose of limiting the same, and the present invention is not limited thereto. Numerous other simple derivations, modifications and substitutions will now occur to those skilled in the art upon reviewing the present disclosure. Such deductions, modifications or alternatives also fall within the scope of the present invention.
Claims (13)
1. The flame-retardant lithium ion battery electrolyte comprises an organic solvent, a lithium salt and an additive, and is characterized in that the additive comprises a phosphate additive and a boron-containing functional additive, wherein the phosphate additive is selected from phosphate additives with four-membered rings shown in the following general formula (2):
wherein, the quaternary ring in the general formula (2) may or may not have double bonds, and the substituent R1 on the ring is selected from hydrogen, fluorine, isocyanate group, cyano group, sulfonyl group, carbonyl group or amino group,
x is selected from lithium ion, substituted straight chain or branched chain alkyl, aryl, alkenyl or alkynyl with 1-8 carbon atoms, and the substituent is selected from fluorine, isocyanate group, cyano, sulfonyl, carbonyl or amino;
based on 100% of the total mass of the electrolyte, the mass of the phosphate additive is 10.0-30.0%, and the mass of the boron-containing functional additive is 0.5-2.0%;
the boron-containing functional additive is trivinyl boron-oxygen hexacyclic or tributenyl boric acid ester.
2. The flame-retardant lithium ion battery electrolyte according to claim 1, wherein the electrolyte is characterized in that, based on 100% of the total mass of the electrolyte,
the mass of the organic solvent is 28.5-89.5%.
3. The flame-retardant lithium ion battery electrolyte according to claim 2, wherein the mass of the organic solvent is 47.8 to 82.6% based on 100% of the total mass of the electrolyte.
4. The flame-retardant lithium ion battery electrolyte according to claim 1, wherein the mass of the lithium salt is 5.0 to 30.0% based on 100% of the total mass of the electrolyte.
5. The flame-retardant lithium ion battery electrolyte according to claim 4, wherein the mass of the lithium salt is 10.0 to 25.0% based on 100% of the total mass of the electrolyte.
6. The flame-retardant lithium ion battery electrolyte according to claim 1, wherein the phosphate additive having a four-membered ring is a compound represented by structural formulas I to IV
7. The flame-retardant lithium ion battery electrolyte according to claim 1, wherein the boron-containing functional additive is trivinylboroxine.
8. The flame-retardant lithium ion battery electrolyte according to claim 1 or 2, wherein the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis (oxalato) phosphate, lithium difluorooxalato borate, lithium bis (oxalato) borate, lithium bis (fluorosulfonato) imide, lithium bis (trifluoromethanesulfonato) imide, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium fluorosulfonate and lithium perchlorate.
9. The flame retardant lithium ion battery electrolyte according to claim 8, wherein the lithium salt comprises lithium bis-fluorosulfonylimide and/or lithium bis-trifluoromethanesulfonylimide.
10. The flame-retardant lithium ion battery electrolyte according to claim 1 or 2, wherein the organic solvent comprises a carbonate-based solvent and/or an ether-based solvent,
the carbonate-based solvent contains a cyclic carbonate and/or a chain carbonate,
the cyclic carbonate contains one or more of vinylene carbonate, fluoroethylene carbonate, ethylene carbonate, propylene carbonate and gamma-butyrolactone;
the chain carbonate comprises one or more than two of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, linear chain or branched chain aliphatic mono-alcohol with 3-8 carbon atoms and carbonate synthesized by carbonic acid;
the ether solvent comprises one or more than two of 1, 3-dioxane, dimethoxymethane, diglyme, perfluoroether, C4-10 linear or branched chain monobasic ether and C4-10 linear or branched chain polybasic ether.
11. The flame-retardant lithium ion battery electrolyte according to claim 10, wherein the ether solvent comprises one or two of 1, 3-dioxane and perfluoroethyl ether.
12. A lithium ion battery is characterized by comprising a positive pole piece, a negative pole piece, electrolyte and a diaphragm, wherein the electrolyte is the flame-retardant lithium ion battery electrolyte according to any one of claims 1 to 11.
13. The preparation method of the flame-retardant lithium ion battery electrolyte is characterized in that the electrolyte is the electrolyte of any one of claims 1 to 11, and comprises the following steps:
adding 5.0-30.0 parts by mass of lithium salt into 28.5-89.5 parts of organic solvent with the water content of less than 20ppm in a glove box with the water content of less than 1ppm and the oxygen content of less than 1ppm, stirring and dissolving, adding 5.0-50.0 parts of phosphate flame-retardant additive and 0.5-2.0 parts of boron-containing functional additive after the lithium salt is completely dissolved, and completely mixing the materials to obtain the flame-retardant lithium ion battery electrolyte.
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| CN111082138A (en) * | 2018-10-19 | 2020-04-28 | Sk新技术株式会社 | Electrolyte for lithium secondary battery and lithium secondary battery including the same |
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| JP4521525B2 (en) * | 2003-08-26 | 2010-08-11 | 独立行政法人 宇宙航空研究開発機構 | Non-flammable non-aqueous electrolyte and lithium ion battery using the same |
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