CN113571771B - Electrolyte for lithium ion battery, preparation method of electrolyte and lithium ion battery - Google Patents
Electrolyte for lithium ion battery, preparation method of electrolyte and lithium ion battery Download PDFInfo
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- CN113571771B CN113571771B CN202110179189.5A CN202110179189A CN113571771B CN 113571771 B CN113571771 B CN 113571771B CN 202110179189 A CN202110179189 A CN 202110179189A CN 113571771 B CN113571771 B CN 113571771B
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 91
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 91
- 239000003792 electrolyte Substances 0.000 title claims abstract description 88
- 238000002360 preparation method Methods 0.000 title abstract description 12
- -1 pyridine ring compound Chemical class 0.000 claims abstract description 78
- 150000001875 compounds Chemical class 0.000 claims abstract description 76
- 239000000654 additive Substances 0.000 claims abstract description 59
- 125000002560 nitrile group Chemical group 0.000 claims abstract description 59
- 125000001174 sulfone group Chemical group 0.000 claims abstract description 51
- 230000000996 additive effect Effects 0.000 claims abstract description 42
- 239000003960 organic solvent Substances 0.000 claims abstract description 32
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 29
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 29
- 229910052744 lithium Inorganic materials 0.000 claims description 24
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 21
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 claims description 14
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 14
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 14
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 14
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 claims description 14
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 claims description 14
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 12
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 10
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 10
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 9
- 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 9
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 8
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- PFJLHSIZFYNAHH-UHFFFAOYSA-N 2,2-difluoroethyl acetate Chemical compound CC(=O)OCC(F)F PFJLHSIZFYNAHH-UHFFFAOYSA-N 0.000 claims description 7
- 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 claims description 7
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 claims description 7
- 229910001486 lithium perchlorate Inorganic materials 0.000 claims description 7
- MCVFFRWZNYZUIJ-UHFFFAOYSA-M lithium;trifluoromethanesulfonate Chemical compound [Li+].[O-]S(=O)(=O)C(F)(F)F MCVFFRWZNYZUIJ-UHFFFAOYSA-M 0.000 claims description 7
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 5
- IFDLFCDWOFLKEB-UHFFFAOYSA-N 2-methylbutylbenzene Chemical compound CCC(C)CC1=CC=CC=C1 IFDLFCDWOFLKEB-UHFFFAOYSA-N 0.000 claims description 5
- LNLFLMCWDHZINJ-UHFFFAOYSA-N hexane-1,3,6-tricarbonitrile Chemical compound N#CCCCC(C#N)CCC#N LNLFLMCWDHZINJ-UHFFFAOYSA-N 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 229910052786 argon Inorganic materials 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- ZPFAVCIQZKRBGF-UHFFFAOYSA-N 1,3,2-dioxathiolane 2,2-dioxide Chemical compound O=S1(=O)OCCO1 ZPFAVCIQZKRBGF-UHFFFAOYSA-N 0.000 claims description 3
- 238000003860 storage Methods 0.000 abstract description 23
- 230000014759 maintenance of location Effects 0.000 abstract description 11
- 230000009471 action Effects 0.000 abstract description 9
- 238000007254 oxidation reaction Methods 0.000 abstract description 4
- 239000011149 active material Substances 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 25
- 239000007774 positive electrode material Substances 0.000 description 17
- 229910052723 transition metal Inorganic materials 0.000 description 17
- 125000004432 carbon atom Chemical group C* 0.000 description 14
- 230000001681 protective effect Effects 0.000 description 14
- 238000012360 testing method Methods 0.000 description 10
- 125000000472 sulfonyl group Chemical group *S(*)(=O)=O 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000007773 negative electrode material Substances 0.000 description 8
- 125000000217 alkyl group Chemical group 0.000 description 7
- 239000003153 chemical reaction reagent Substances 0.000 description 7
- 238000004090 dissolution Methods 0.000 description 7
- 229910052736 halogen Inorganic materials 0.000 description 7
- 125000001424 substituent group Chemical group 0.000 description 7
- 125000004093 cyano group Chemical group *C#N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 150000002367 halogens Chemical class 0.000 description 6
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 description 6
- 230000002195 synergetic effect Effects 0.000 description 6
- 239000002000 Electrolyte additive Substances 0.000 description 5
- 239000011230 binding agent Substances 0.000 description 5
- ABDBNWQRPYOPDF-UHFFFAOYSA-N carbonofluoridic acid Chemical class OC(F)=O ABDBNWQRPYOPDF-UHFFFAOYSA-N 0.000 description 5
- 239000006258 conductive agent Substances 0.000 description 5
- 125000001153 fluoro group Chemical group F* 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 239000011267 electrode slurry Substances 0.000 description 4
- 239000008151 electrolyte solution Substances 0.000 description 4
- 229940021013 electrolyte solution Drugs 0.000 description 4
- 230000008961 swelling Effects 0.000 description 4
- 150000003624 transition metals Chemical class 0.000 description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 3
- 239000002841 Lewis acid Substances 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- VEWLDLAARDMXSB-UHFFFAOYSA-N ethenyl sulfate;hydron Chemical compound OS(=O)(=O)OC=C VEWLDLAARDMXSB-UHFFFAOYSA-N 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 150000007517 lewis acids Chemical class 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- JUJWROOIHBZHMG-UHFFFAOYSA-N pyridine Substances C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 3
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000006245 Carbon black Super-P Substances 0.000 description 2
- 229910012258 LiPO Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 125000003342 alkenyl group Chemical group 0.000 description 2
- 125000003545 alkoxy group Chemical group 0.000 description 2
- 125000002947 alkylene group Chemical group 0.000 description 2
- 125000000304 alkynyl group Chemical group 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000006256 anode slurry Substances 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002109 single walled nanotube Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000009966 trimming Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- WXNUAYPPBQAQLR-UHFFFAOYSA-N B([O-])(F)F.[Li+] Chemical compound B([O-])(F)F.[Li+] WXNUAYPPBQAQLR-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910010941 LiFSI Inorganic materials 0.000 description 1
- 229910013716 LiNi 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
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000006183 anode active material Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 239000006182 cathode active material Substances 0.000 description 1
- 125000003636 chemical group Chemical group 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 150000003457 sulfones Chemical class 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- NDZWKTKXYOWZML-UHFFFAOYSA-N trilithium;difluoro oxalate;borate Chemical compound [Li+].[Li+].[Li+].[O-]B([O-])[O-].FOC(=O)C(=O)OF NDZWKTKXYOWZML-UHFFFAOYSA-N 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to an electrolyte for a lithium ion battery, a preparation method of the electrolyte and the lithium ion battery. The electrolyte for the lithium ion battery comprises an organic solvent, a lithium salt and an additive, wherein the additive comprises a pyridine ring compound and a compound containing a sulfone group and a nitrile group, the pyridine ring compound is selected from the compounds shown in the general formula (I), and the compound containing the sulfone group and the nitrile group is selected from the compounds shown in the general formula (II). By utilizing the combined action of the pyridine ring compound and the compound containing the sulfone group and the nitrile group, the oxidation reaction of the electrolyte on the surfaces of the positive electrode and the negative electrode is inhibited, the active materials of the positive electrode and the negative electrode are stabilized, the circulation capacity retention rate and the circulation performance of the battery are improved, and the expansion of the battery during high-temperature storage is slowed down.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrolyte for a lithium ion battery, a preparation method of the electrolyte and the lithium ion battery.
Background
The lithium ion battery is widely applied to the fields of consumer electronics products, new energy power automobiles, energy storage and the like. With the miniaturization of consumer electronic products and the increasing demand of people on the endurance mileage of new energy vehicles, the lithium ion battery is urgently required to be developed towards the direction of high energy density, and the improvement of the upper limit voltage of the lithium ion battery and the use of positive and negative electrode materials with high theoretical capacity are effective ways for improving the energy density of the lithium ion battery.
However, high-voltage lithium cobaltate, high nickel and other high-theoretical capacity positive active materials are prone to transition metal dissolution during cycling and high-temperature storage processes, which aggravates side reactions of the electrolyte for the lithium ion battery, and leads to poor cycling and high-temperature storage performance. High-capacity negative active materials such as silicon-based negative electrodes and the like can cause continuous fracture and generation of an SEI (solid electrolyte interface) film on the surface of the negative active material due to large volume expansion, so that electrolyte is continuously consumed, and the capacity is continuously attenuated. Therefore, it is necessary to develop an electrolyte capable of matching with high-capacity positive and negative electrode materials to solve the problems that the electrolyte is continuously consumed and the capacity of the lithium ion battery is continuously attenuated.
The Chinese patent application CN110943253A discloses a high-voltage lithium ion battery combined electrolyte additive, an electrolyte and a battery thereof, wherein the high-voltage lithium ion battery combined electrolyte additive is formed by mixing sulfone compounds and fluoro-carbonate compounds. The patent takes the fluoro-carbonate as a main additive, the fluoro-carbonate is easy to decompose to generate gas, and in addition, the cost of the fluoro-carbonate is high, so that the cost of the battery is high, and the application of the fluoro-carbonate is limited.
Chinese patent application CN111244543A discloses a high-voltage lithium ion battery electrolyte additive, an electrolyte, a battery and a formation method thereof, wherein the high-voltage lithium ion battery electrolyte additive is a pyridine compound, and the pyridine compound additive is sufficiently decomposed by formation at high temperature and high voltage, however, the application of the high-voltage lithium ion battery electrolyte additive is limited by using the pyridine compound alone under the conditions of high temperature performance and cycle performance.
Disclosure of Invention
The invention provides an electrolyte for a lithium ion battery, a preparation method of the electrolyte and the lithium ion battery, and aims to solve the problems that a lithium battery in the prior art is poor in electrochemical performance, particularly poor in cycle stability, serious in cycle capacity attenuation, serious in battery expansion during high-temperature storage and the like.
The purpose of the invention can be realized by the following technical scheme:
[1] an electrolyte for a lithium ion battery comprises an organic solvent, a lithium salt and an additive, and is characterized in that the additive comprises a pyridine ring compound and a compound containing a sulfone group and a nitrile group;
wherein the pyridine ring compound is selected from the compounds shown in the following general formula (I):
wherein R is 1 、R 2 、R 3 、R 4 、R 5 Each independently selected from hydrogen atom, fluorine atom, and substituted or unsubstituted alkyl group with 1-6 carbon atoms, and the substituent is selected from cyano or halogen;
the compound containing sulfuryl and nitrile is selected from compounds shown in the following general formula (II):
wherein R is 6 Is selected from substituted or unsubstituted alkylene with 1 to 8 carbon atoms, and the substituent is selected from cyano or halogen;
R 7 is selected from substituted or unsubstituted alkyl with 1 to 8 carbon atoms, substituted or unsubstituted alkenyl with 2 to 8 carbon atoms, substituted or unsubstituted alkynyl with 2 to 8 carbon atoms, substituted or unsubstituted alkoxy with 1 to 8 carbon atoms and substituted or unsubstituted phenyl with 6 to 10 carbon atoms, and the substituent is selected from cyano or halogen.
[2] The electrolyte for a lithium ion battery according to [1], wherein the pyridine ring compound comprises at least one of compounds represented by structural formulae I to X:
[3] the electrolyte for the lithium ion battery as recited in [1], wherein the compound containing the sulfone group and the nitrile group comprises at least one of compounds represented by structural formulas XI to XXI:
[4] the electrolyte for a lithium ion battery according to [1], which is characterized by comprising 70 to 85 parts of the organic solvent, 5 to 15 parts of the lithium salt and 1.5 to 15 parts of the additive by 100 parts of the total mass of the electrolyte;
the additive comprises 0.1-10.0 parts of pyridine ring compound and 0.2-10.0 parts of compound containing sulfuryl and nitrile group.
[5] The electrolyte for a lithium ion battery according to [4], which is characterized by comprising 70 to 85 parts of the organic solvent, 5 to 15 parts of the lithium salt and 1.5 to 15 parts of the additive by 100 parts of the total mass of the electrolyte;
the additive comprises 0.1 to 10.0 parts of pyridine ring compound, 0.2 to 10.0 parts of sulfuryl and nitrile group-containing compound and 1.0 to 14.5 parts of other additives,
the other additive comprises one or more than two of 1, 3-propane sultone, ethylene sulfate, fluoroethylene carbonate, vinylene carbonate, 1,3, 6-hexanetricarbonitrile, 1, 3-propene sultone and lithium difluoro oxalato borate.
[6] The electrolyte solution for a lithium ion battery according to [1], wherein the organic solvent contains one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ -butyrolactone, methyl formate, ethyl propionate, propyl propionate, and difluoroethyl acetate.
[7] The electrolyte for a lithium ion battery according to [1], wherein the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium bis (fluorosulfonyl) imide, lithium bisoxalato borate, lithium hexafluoroarsenate, lithium perchlorate, and lithium trifluoromethanesulfonate.
[8] A method for producing an electrolyte solution for a lithium ion battery, characterized in that the electrolyte solution is any one of the electrolyte solutions [1] to [7], comprising the steps of:
(1) Setting the water oxygen value to be less than 5ppm in a glove box filled with argon, preparing 70-85 parts of organic solvent based on 100 parts of the total mass of the electrolyte,
the organic solvent comprises one or more than two of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, gamma-butyrolactone, methyl formate, ethyl propionate, propyl propionate and difluoroethyl acetate;
(2) Based on 100 parts of the total mass of the electrolyte, 1.5-15 parts of additive is prepared,
the additive comprises 0.1 to 10.0 parts of pyridine ring compound and 0.2 to 10.0 parts of compound containing sulfuryl and nitrile group, or,
the additive comprises 0.1 to 10.0 parts of pyridine ring compound, 0.2 to 10.0 parts of sulfone group and nitrile group-containing compound and 1.0 to 14.5 parts of other additives;
(3) Mixing 70-85 parts of organic solvent and 5-15 parts of lithium salt at room temperature to obtain a mixture of the organic solvent and the lithium salt, adding 1.5-15 parts of additive to obtain the electrolyte for the lithium ion battery,
the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium bis (fluorosulfonyl) imide, lithium bis (oxalato) borate, lithium hexafluoroarsenate, lithium perchlorate and lithium trifluoromethanesulfonate.
[9] A lithium ion battery comprises electrolyte, a positive plate, a negative plate and a diaphragm, and is characterized in that the electrolyte is the electrolyte for the lithium ion battery in any one of the items [1] to [7 ].
The invention has the following beneficial effects:
the pyridine ring compound can form a compact and stable protective film in the negative electrode of the lithium ion battery, inhibit volume expansion of a negative electrode active material in the charging and discharging process, and simultaneously, the pyridine ring compound can perform a complex reaction with a transition metal element in a positive electrode active material on the surface of a positive electrode to stabilize the transition metal element of the positive electrode, so that the reaction of an electrolyte on the surface of the positive electrode and the dissolution of the transition metal element are effectively inhibited, particularly, when fluorine atoms are contained, the fluorine atoms can generate lithium fluoride, and the stability of an SEI film can be improved.
Regarding the compound containing the sulfone group and the nitrile group, the sulfone group can be oxidized under the action of Lewis acid and a high-oxidation-state positive electrode active material to generate a protective film containing sulfonic acid alkyl lithium or sulfonic acid alkyl compound, the nitrile group can be complexed with transition metal in the positive electrode active material and the surface of the positive electrode to inhibit the dissolution of the transition metal element, and the compound containing the sulfone group and the nitrile group can inhibit the oxidation reaction of the electrolyte on the surface of the positive electrode by utilizing the combined action of the nitrile group and the sulfone group of the compound containing the sulfone group and the nitrile group, so that the positive electrode material is stabilized, and the expansion of the battery during high-temperature storage is inhibited.
According to the invention, the pyridine ring compound, the compound containing the sulfone group and the nitrile group and the like are combined in the electrolyte as additives, and the synergistic effect of the two compounds is utilized, so that the stability of the high-capacity anode and cathode materials can be improved, the redox reaction of the electrolyte on the surfaces of the anode and cathode is inhibited, the electrochemical performance, particularly the cycle performance, of the high-energy density lithium ion battery is improved, and the battery expansion during high-temperature storage is inhibited.
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 25mol% means 5mol% or more and 25mol% or less.
The present invention is further described below.
The invention provides an electrolyte for a lithium ion battery, which comprises an organic solvent, a lithium salt and an additive, and is characterized in that the additive comprises a pyridine ring compound and a compound containing a sulfone group and a nitrile group;
wherein the pyridine ring compound is selected from the compounds shown in the following general formula (I):
wherein R is 1 、R 2 、R 3 、R 4 、R 5 Each independently selected from hydrogen atom, fluorine atom, and substituted or unsubstituted alkyl group with 1-6 carbon atoms, and the substituent is selected from cyano or halogen;
the compound containing the sulfone group and the nitrile group is selected from compounds shown in the following general formula (II):
wherein R is 6 Is selected from substituted or unsubstituted alkylene with 1 to 8 carbon atoms, and the substituent is selected from cyano or halogen;
R 7 is selected from substituted or unsubstituted alkyl with 1 to 8 carbon atoms, substituted or unsubstituted alkenyl with 2 to 8 carbon atoms, substituted or unsubstituted alkynyl with 2 to 8 carbon atoms, substituted or unsubstituted alkoxy with 1 to 8 carbon atoms and substituted or unsubstituted phenyl with 6 to 10 carbon atoms, and the substituent is selected from cyano or halogen.
The pyridine ring compound can participate in polymerization in a lithium ion battery cathode to form a compact and stable protective film, and if a substituent on the pyridine ring compound is a halogen fluorine atom, lithium fluoride can be generated, so that the stability of an SEI film is improved, the volume expansion of a cathode active material in the charge-discharge process is inhibited, meanwhile, the pyridine ring compound can perform a complex reaction with a transition metal element in an anode active material on the surface of an anode, the transition metal element of the anode is stabilized, and the reaction of an electrolyte on the surface of the anode and the dissolution of the transition metal element are effectively inhibited.
The sulfone group of the compound containing the sulfone group and the nitrile group can be oxidized under the action of Lewis acid and a high-oxidation-state positive electrode active material to generate a protective film containing sulfonic acid alkyl lithium or sulfonic acid alkyl compound, the nitrile group can be complexed with transition metal in the positive electrode active material and the surface of the positive electrode to inhibit the dissolution of the transition metal element, and the compound containing the sulfone group and the nitrile group can inhibit the oxidation reaction of the electrolyte on the surface of the positive electrode and stabilize the positive electrode active material by enabling the nitrile group and the sulfone group of the compound containing the sulfone group and the nitrile group to play a synergistic effect.
In some embodiments of the invention, the pyridine ring compound comprises at least one of compounds of structural formulae I through X:
the pyridine ring compound preferably comprises at least one compound of the formulae I, VI, VII, X.
In some embodiments of the present invention, the compound having a sulfone group and a nitrile group comprises at least one of the compounds of formula XI through formula XXI:
the compound of the sulfone group and the nitrile group preferably comprises at least one of the compounds shown in structural formulas XI, XII, XV, XVI and XVIII.
In some embodiments of the present invention, the electrolyte comprises 70 to 85 parts of the organic solvent, 5 to 15 parts of the lithium salt, and 1.5 to 15 parts of the additive, based on 100 parts of the total mass of the electrolyte;
the additive comprises 0.1 to 10.0 parts of pyridine ring compound and 0.2 to 10.0 parts of compound containing sulfuryl and nitrile group;
preferably, the additive comprises 0.1 to 6.5 parts of pyridine ring compound and 0.2 to 8.5 parts of compound containing sulfuryl and nitrile groups;
preferably, the additive comprises 0.1-4.8 parts of pyridine ring compound and 0.2-4.9 parts of compound containing sulfuryl and nitrile groups.
In the electrolyte of the invention, when the pyridine ring compound is too low relative to 100 parts of the electrolyte, the formed protective film is not compact enough, and the side reaction of the electrolyte cannot be effectively inhibited; when the pyridine ring compound is too high, the protective film formed therefrom is too thick, and the impedance increases, which may adversely affect the performance of the lithium ion battery.
In the electrolyte, when the compound containing the sulfone group and the nitrile group is too low relative to 100 parts of the electrolyte, a complex structure formed by the nitrile group and a transition metal element in a positive active material is not compact enough, the sulfone group cannot form a compact protective layer, the side reaction of the electrolyte cannot be effectively inhibited, and the performance of a lithium ion battery cannot be improved; when the compound containing the sulfone group and the nitrile group is too high, the impedance of the formed protective film is too high, which is not beneficial to the extraction and insertion of lithium ions, and the performance of the lithium ion battery is deteriorated.
In some embodiments of the present invention, the electrolyte comprises 70 to 85 parts of the organic solvent, 5 to 15 parts of the lithium salt, and 1.5 to 15 parts of the additive, based on 100 parts of the total mass of the electrolyte;
the additive comprises 0.1 to 10.0 parts of pyridine ring compound, 0.2 to 10.0 parts of sulfone group and nitrile group-containing compound and 1.0 to 14.5 parts of other additives,
preferably, the additive comprises 0.1 to 6.5 parts of pyridine ring compound, 0.2 to 8.5 parts of sulfone group and nitrile group-containing compound and 1.0 to 14.5 parts of other additives,
preferably, the additive comprises 0.2 to 1.5 parts of pyridine ring compound, 0.2 to 2.0 parts of sulfone group and nitrile group-containing compound and 1.0 to 14.5 parts of other additives,
the other additive comprises one or more than two of 1, 3-propane sultone, ethylene sulfate, fluoroethylene carbonate, vinylene carbonate, 1,3, 6-hexanetricarbonitrile, 1, 3-propene sultone and lithium difluoro oxalato borate.
Among them, 1, 3-Propane Sultone (PS), vinyl sulfate (DTD) and 1, 3-Propene Sultone (PST) can form a good protective film on the surface of the positive electrode of the lithium ion battery, stabilize the positive electrode material and inhibit the decomposition of the electrolyte on the surface of the positive electrode. Fluoroethylene carbonate (FEC) and Vinylene Carbonate (VC) can form a stable and elastic protective film on the surface of the lithium ion battery negative electrode, and inhibit the reduction reaction of the electrolyte on the lithium ion battery negative electrode and the volume expansion of the negative electrode. If the mass percentage of the fluoroethylene carbonate (FEC) in the electrolyte is too high, the high-temperature performance of the lithium ion battery is deteriorated. Lithium difluoro oxalate borate (LiODFB) can optimize the structure of the anode and cathode protective films, reduce the impedance of the lithium ion battery and further improve the performance of the lithium ion battery. The 1,3, 6-Hexanetricarbonitrile (HTCN) can consume redundant energy when the lithium ion battery is overcharged, and the safety performance of the lithium ion battery is improved. The combination and ratio of the compounds in the other additives are not particularly limited as long as they can exert the predetermined action.
In some embodiments of the present invention, the organic solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ -butyrolactone, methyl formate, ethyl propionate, propyl propionate, and difluoroethyl acetate.
Preferably, the organic solvent comprises one or more of ethylene carbonate, propylene carbonate, diethyl carbonate and ethyl methyl carbonate.
In some embodiments of the invention, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium bis (fluorosulfonyl) imide, lithium bis (oxalato) borate, lithium hexafluoroarsenate, lithium perchlorate, and lithium trifluoromethanesulfonate.
Preferably, the lithium salt is one or more of lithium hexafluorophosphate and lithium difluorophosphate, lithium hexafluorophosphate and lithium bis (fluorosulfonyl) imide.
In the electrolyte of the present invention, the concentration of the lithium salt may be 0.8 to 1.8M. Preferably, the concentration of the lithium salt may be 1 to 1.2M.
The invention also provides a preparation method of the electrolyte for the lithium ion battery, which is characterized in that the electrolyte is the electrolyte and comprises the following steps:
(1) Setting the water oxygen value to be less than 5ppm in a glove box filled with argon, preparing 70-85 parts of organic solvent based on 100 parts of the total mass of the electrolyte,
the organic solvent comprises one or more than two of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, gamma-butyrolactone, methyl formate, ethyl propionate, propyl propionate and difluoroethyl acetate;
(2) Based on 100 parts of the total mass of the electrolyte, 1.5 to 15 parts of additive are prepared,
the additive comprises 0.1 to 6.5 parts of pyridine ring compound and 0.2 to 8.5 parts of compound containing sulfuryl and nitrile group, or,
the additive comprises 0.2 to 1.5 parts of pyridine ring compound, 0.2 to 2.0 parts of sulfone group and nitrile group-containing compound and 1.0 to 14.5 parts of other additives;
(3) At room temperature, mixing 70-85 parts of organic solvent with 5-15 parts of lithium salt to obtain a mixture of the organic solvent and the lithium salt, and then adding 1.5-15 parts of additive to obtain electrolyte for the lithium ion battery;
the lithium salt comprises one or more than two of lithium hexafluorophosphate, lithium difluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium bis (fluorosulfonyl) imide, lithium bis (oxalato) borate, lithium hexafluoroarsenate, lithium perchlorate and lithium trifluoromethanesulfonate.
In addition, the invention also provides a lithium ion battery, which comprises electrolyte, a positive plate, a negative plate and a diaphragm, and is characterized in that the electrolyte is the electrolyte for the lithium ion battery.
The positive plate comprises a positive current collector and a positive diaphragm coated on the positive current collector. The positive electrode membrane may include a positive electrode active material, a binder, and a conductive agent. And coating the positive electrode slurry containing the positive electrode active material, the binder and the conductive agent on the positive electrode current collector, and drying the positive electrode slurry to obtain the positive electrode plate. Similarly, negative electrode slurry containing a negative electrode active material, a binder and a conductive agent is coated on a negative electrode current collector, and a negative electrode sheet is obtained after the negative electrode slurry is dried.
The separator of the present invention is not particularly limited as long as it has a predetermined effect.
The present invention will be described in further detail with reference to examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present application.
The abbreviations for the compounds used in the following examples and comparative examples are as follows:
among other additives, 1, 3-propane sultone is PS, vinyl sulfate is DTD, fluoroethylene carbonate is FEC, vinylene carbonate is VC,1,3, 6-hexanetricarbonitrile is HTVN,1, 3-propene sultone is PST, and lithium difluoroborate is LiODFB.
In the organic solvent, ethylene carbonate is EC, propylene carbonate is PC, dimethyl carbonate is DMC, diethyl carbonate is DEC, and methyl ethyl carbonate is EMC.
The raw materials or reagents used in the examples of the present invention are all purchased from mainstream manufacturers in the market, and are all commodities of analytical grade or higher, and are not particularly limited as long as they can play the intended role. The specific techniques or conditions not specified in the examples of the present invention are performed according to the techniques or conditions described in the literature in the art or according to the product specification. The apparatus or raw materials used are not indicated by the manufacturer, and are all conventional products that can be obtained commercially, and the reagents used are not indicated by the manufacturer or concentration, and are all analytical pure-grade reagents that can be obtained conventionally, as long as the desired effect can be achieved, and are not particularly limited. The apparatus such as a glove box, a stirrer, an oven, a coater, a thermostat, a high temperature furnace, and a roll squeezer used in the embodiments of the present invention are not particularly limited as long as they can perform the intended functions.
The raw materials and equipment used in the following examples, comparative examples are as follows:
PC, EC, DEC and EMC: battery grade purity, purchased from Shandong Shi Dashenghua chemical group, inc.;
FEC, VC, and PS: battery grade purity, purchased from Jiangsu Huasheng materials science and technology group, inc.;
DTD, liODFB and LiPO 2 F 2 : battery grade purity, purchased from alatin chemical reagent net;
LiPF 6 : battery grade purity, purchased from polyfluoro chemical industries, ltd;
LiFSI: battery grade purity, available from frei fine chemicals, inc;
HTCN: battery grade purity, purchased from korea Tianbao industries co;
PST: battery grade purity, purchased from Shijiazhuang Shengtai chemical Co., ltd;
compounds of structural formulae I, VI, VII, X: battery grade purity, purchased from national medicine reagent net, mobei chemical net;
compounds of structural formulae XI, XII, XV, XVI, XVIII: battery grade purity, purchased from the alatin chemical reagent net, the national drug reagent net, the mobei chemical net.
Example 1
Preparing an electrolyte:
(1) In a glove box filled with argon gas at room temperature, setting a water oxygen value to be less than 5ppm, and mixing 16 parts of Ethylene Carbonate (EC), 12 parts of Propylene Carbonate (PC), 36 parts of diethyl carbonate (DEC) and 16 parts of Ethyl Methyl Carbonate (EMC) to obtain an organic solvent;
(2) Uniformly mixing 2 parts of pyridine ring compound shown in a structural formula I and 3 parts of compound containing sulfonyl and nitrile groups shown in a structural formula XVI, and preparing to obtain an additive;
(3) An organic solvent was mixed with 15 parts of a lithium salt (containing 13 parts of LiPF) 6 And 2 parts of LiPO 2 F 2 ) And mixing to obtain a mixture of the organic solvent and the lithium salt, adding the additive, and stirring uniformly by using a stirrer at 200rpm for 30 minutes to obtain the electrolyte for a lithium battery of example 1.
Examples 2 to 11
The procedure of the preparation method was substantially the same as in example 1, except for the relevant components and contents, as shown in Table 1.
Comparative examples 1 to 8
The procedure of the preparation method was substantially the same as in example 1, except for the relevant components and contents, as shown in Table 1.
Table 1 shows the process recipes for each example and each comparative example, wherein the total mass of the electrolyte is 100 parts. In columns 4 and 5 of table 1, each structural formula represents a compound represented by each structural formula.
TABLE 1
The preparation and performance testing of the lithium ion battery are described below.
Preparation of (1) lithium ion battery
(1) Preparing a positive pole piece:
LiNi to be an active material 0.8 Co 0.1 Mn 0.1 O 2 The conductive carbon black Super P is used as a conductive agent, and the polyvinylidene fluoride is used as a binder, wherein the mass ratio of the conductive carbon black Super P to the polyvinylidene fluoride is 97:1.5:1.5 fully stirring and mixing in an N-methyl pyrrolidone solvent system to prepare anode slurry, uniformly coating the anode slurry on an anode current collector aluminum foil with the thickness of 20 mu m, drying at 100 ℃, cold pressing, trimming, cutting and slitting, drying for 4 hours at 85 ℃, and welding lugs to obtain the anode piece.
(2) Preparing a negative pole piece:
the preparation method comprises the following steps of mixing natural graphite serving as a negative electrode active material, conductive carbon black (Super P) serving as a conductive agent, styrene Butadiene Rubber (SBR) serving as a binder, sodium carboxymethylcellulose (CMC) serving as a thickening agent and single-walled carbon nanotubes (SWCNT) according to a mass ratio of 95:1:2.5:1.4:0.1, fully stirring in a deionized water solution system to prepare negative slurry, uniformly coating the negative slurry on a negative current collector copper foil with the thickness of 10um, drying at 75 ℃, cold pressing, trimming, cutting into pieces, slitting, and welding tabs to obtain a negative pole piece.
(3) Preparation of a separation film:
a polyethylene film (PE) was used as the separator.
(4) Assembling the lithium ion battery:
winding the positive pole piece, the negative pole piece and the isolating film to prepare a naked battery cell, packaging by using an aluminum plastic film, and vacuumizing at 85 ℃ to-0.95 multiplied by 10 relative vacuum 5 Pa, dried at 100 ℃ to a moisture content of 100ppm or less. And injecting the electrolyte prepared in the examples 1-11 and the comparative examples 1-8, carrying out vacuum packaging, and carrying out the procedures of standing, hot and cold pressing, formation, liquid extraction, capacity separation and the like to prepare the lithium ion battery.
Performance test of (2) lithium ion battery
(1) Cycle performance test
The lithium ion batteries of examples 1 to 11 and comparative examples 1 to 8 were placed in a thermostatic chamber of 25 ℃ and a thermostatic chamber of 45 ℃ respectively, and left to stand for 30min to keep the temperature of the lithium ion batteries constant. The lithium ion battery reaching a constant temperature was charged at a constant current of 0.5C to a voltage of 4.2V, then charged at a constant voltage of 4.2V to a current of 0.025C, and then discharged at a constant current of 1C to a voltage of 2.75V, which is a charge-discharge cycle. Thus, the charge and discharge were repeated, and the capacity retention ratio after each lithium ion battery was cycled 300 times was calculated, respectively. The capacity retention of the lithium ion battery was calculated as follows:
capacity retention rate = (300 th cycle discharge capacity/first cycle discharge capacity) × 100%
(2) High temperature storage volume expansion test
The lithium ion battery is charged to 4.2V at a constant current of 0.5C, and then charged to a full charge state at a constant voltage of 0.025C. The thickness THK1 of the lithium ion battery in the fully charged state was tested. And (4) placing the fully-charged battery cell in a high-temperature furnace at 60 ℃ for 7 days, and testing the thickness THK2 of the battery cell. The swelling ratio of the lithium ion battery was calculated as follows:
swelling rate = (THK 2-THK 1)/THK 1 × 100%.
The test results are shown in table 2.
TABLE 2
As shown in table 2, as a result of analyzing the test results of examples 1 to 11 and comparative example 1, in comparative example 1, since the pyridine ring compound and the compound containing a sulfone group and a nitrile group were not added, swelling of the battery occurred in the cycle performance test, and the battery was not able to be cycled, and the swelling rate was high when stored at 60 ℃ for 7 days. However, in examples 1 to 11 of the present invention, by adding the pyridine ring compound and the compound containing the sulfone group and the nitrile group to the electrolyte at the same time, compared with comparative example 1, the cycle capacity retention rate and the high-temperature cycle retention rate are significantly increased, and the volume expansion rate of the battery after storage at 60 ℃ for 7 days is improved, which proves that the pyridine ring compound and the compound containing the sulfone group and the nitrile group have good cooperativity, and the cycle performance and the high-temperature storage performance of the lithium ion battery can be improved.
As shown in table 2, it is known from the results of the tests performed in examples 1 to 11 and comparative example 2 that the pyridine ring compound is added alone in comparative example 2, which results in high volume expansion rate of high-temperature storage and poor cycle performance, but the pyridine ring compound and the compound containing sulfone group and nitrile group are added simultaneously in examples 1 to 11, and the synergistic effect of the two compounds is exerted with the addition of the sulfone group and the nitrile group compound, thereby improving the cycle performance and the high-temperature storage performance of the lithium ion battery.
As shown in table 2, it is understood from the results of the tests of examples 1 to 11 and comparative example 3 that the addition of the compound containing a sulfone group and a nitrile group alone in comparative example 3 results in a high volumetric expansion rate of high-temperature storage and a reduction in cycle performance, but the addition of the compound containing a sulfone group and a nitrile group in examples 1 to 6 not only results in a high volumetric expansion rate of high-temperature storage, but also results in the synergistic effect of the two additive compounds with the addition of the pyridine ring compound, thereby improving cycle performance and high-temperature storage performance of the lithium ion battery.
As shown in table 2, it can be seen from the results of the tests of examples 7 to 11 and comparative example 4 that, in comparative example 4, the addition of other additives alone, the absence of the pyridine ring compound and the compound containing sulfone and nitrile groups, resulted in low capacity retention in battery cycles and high expansion rate after 7 days of storage at 60 ℃. However, in examples 7 to 11 of the present invention, by adding the pyridine ring compound, the compound containing the sulfone group and the nitrile group, and other additives to the electrolyte at the same time, compared to comparative example 4, the cycle capacity retention rate and the high-temperature cycle retention rate are both significantly improved, the volume expansion rate of the battery after storage at 60 ℃ for 7 days is improved, and the cycle performance and the high-temperature storage performance of the lithium ion battery are improved.
As shown in table 2, it can be seen from the results of the tests conducted in examples 7 to 11 and comparative examples 5 and 6 that the addition of only the pyridine ring compound and other additives in comparative example 5 and the addition of only the compound containing the sulfone group and the nitrile group and other additives in comparative example 6 results in poor cycle performance and a high volume expansion rate of the battery, but the addition of not only the pyridine ring compound but also the compound containing the sulfone group and the nitrile group and other additives in examples 7 to 11 results in the synergistic effect of the two additive compounds and significantly improves the cycle performance and the high-temperature storage performance of the lithium ion battery compared to comparative examples 5 and 6.
As shown in table 2, when the test results of examples 1 to 6 and comparative examples 7 and 8 were analyzed, it was found that the addition of an excessive amount of the pyridine ring compound in comparative example 7 and the addition of an excessive amount of the compound containing a sulfone group and a nitrile group in comparative example 8 resulted in the deterioration of cycle characteristics of the lithium ion battery and the volume expansion rate of the battery after 7 days of storage at 60 ℃. The reason for this may be that an excessive amount of the pyridine ring compound causes an excessively thick protective film formed on the surface of the lithium ion battery electrode, and an excessive amount of the compound containing a sulfone group and a nitrile group increases the resistance of the lithium ion battery protective film, which is disadvantageous in improving cycle performance and high-temperature storage performance.
Without limiting the invention, the mechanism by which the electrolyte of the invention is excellent may be as follows: the pyridine ring compound can participate in polymerization in the negative electrode of the lithium ion battery to form a compact and stable protective film (lithium fluoride can be generated under the condition of containing fluorine atoms), the stability of an SEI film is improved, the volume expansion of a negative electrode active material in the charging and discharging process is inhibited, meanwhile, the pyridine ring compound can perform a complex reaction with a transition metal element in a positive electrode active material on the surface of the positive electrode, the transition metal element of the positive electrode is stabilized, the reaction of an electrolyte on the surface of the positive electrode and the dissolution of the transition metal element are effectively inhibited, the cycle performances of the lithium battery such as the cycle capacity retention rate and the like are improved, and the attenuation of the cycle capacity is inhibited. The sulfone group in the compound containing the sulfone group and the nitrile group can be oxidized under the action of Lewis acid and a high-oxidation-state positive electrode active material to generate a protective film containing sulfonic acid alkyl lithium or sulfonic acid alkyl compound, and the nitrile group can be complexed with transition metal in the positive electrode active material and the surface of the positive electrode to inhibit the dissolution of the transition metal element. By utilizing the combined action of nitrile group and sulfone group, the compound containing the sulfone group and the nitrile group can inhibit the oxidation reaction of the electrolyte on the surface of the anode, stabilize the anode material and inhibit the volume expansion of the battery during high-temperature storage.
According to the electrolyte disclosed by the invention, the compounding amount of each component is precisely adjusted, and the synergistic effect of the pyridine ring compound and the compound containing the sulfone group and the nitrile group is utilized, so that the stability of a high-capacity anode and cathode material can be improved, the redox reaction of the electrolyte on the surface of an anode and a cathode is inhibited, the cycle performance and the high-temperature storage performance of a lithium ion battery are successfully improved, and the electrochemical performance of the high-energy-density lithium ion battery, especially the capacity retention rate performance under cyclic charge and discharge, is improved.
In the above examples 1 to 11 and comparative examples 1 to 8, only ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate were used as the organic solvent, and since ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ -butyrolactone, methyl formate, ethyl propionate, propyl propionate and difluoroethyl acetate were used as the organic solvent in the reaction of preparing the electrolyte according to the present invention, the same or similar effects in action and technical effects to those used as the organic solvent in the examples were applied to the present invention.
In examples 1 to 11 and comparative examples 1 to 8, lithium hexafluorophosphate, lithium difluorophosphate and lithium bis (fluorosulfonyl) imide were used as the lithium salt, and lithium difluorophosphate, lithium hexafluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium bis (oxalato) borate, lithium hexafluoroarsenate, lithium perchlorate and lithium trifluoromethanesulfonate were used as the lithium salt in the reaction for preparing the electrolyte according to the present invention, and the same effects in action and technical effect as those of the lithium salt used in the examples are applicable to the present invention.
The pyridine ring compound and the compound containing the sulfone group and the nitrile group are precisely combined and used in the electrolyte for the lithium ion battery, so that the high-low temperature cycle performance of the lithium ion battery and the battery expansion rate during high-temperature storage can be obviously improved, the application range of the lithium ion battery is effectively expanded, and the pyridine ring compound and the compound containing the sulfone group and the nitrile group also have the characteristics of small addition amount, low cost and simple synthesis, and are beneficial to industrial production.
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 claims of the present invention.
Claims (5)
1. The electrolyte for the lithium ion battery consists of an organic solvent, lithium salt and an additive, and is characterized in that the additive consists of a pyridine ring compound, a compound containing a sulfone group and a nitrile group and other additives;
wherein, the first and the second end of the pipe are connected with each other,
the pyridine ring compound is at least one of the following compounds:
the compound of the sulfone group and the nitrile group is at least one of the following compounds:
based on 100 parts of the total mass of the electrolyte for the lithium ion battery, the electrolyte consists of 70-85 parts of the organic solvent, 5-15 parts of the lithium salt and 1.5-15 parts of the additive;
the additive consists of 0.2 to 1.5 parts of pyridine ring compound, 0.2 to 2 parts of sulfone group and nitrile group-containing compound and 1.0 to 14.5 parts of other additives,
the other additive is one or more than two of 1, 3-propane sultone, ethylene sulfate, fluoroethylene carbonate, vinylene carbonate, 1,3, 6-hexanetricarbonitrile, 1, 3-propene sultone and lithium difluoro oxalato borate.
2. The electrolyte for a lithium ion battery according to claim 1, wherein the organic solvent contains one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ -butyrolactone, methyl formate, ethyl propionate, propyl propionate, and difluoroethyl acetate.
3. The electrolyte for a lithium ion battery according to claim 1, wherein the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium bis (fluorosulfonyl) imide, lithium bisoxalato borate, lithium hexafluoroarsenate, lithium perchlorate, and lithium trifluoromethanesulfonate.
4. A method for preparing the electrolyte for a lithium ion battery according to any one of claims 1 to 3, comprising the steps of:
(1) Setting the water oxygen value to be less than 5ppm in a glove box filled with argon, preparing 70-85 parts of organic solvent by 100 parts of the total mass of the electrolyte for the lithium ion battery,
the organic solvent comprises one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, gamma-butyrolactone, methyl formate, ethyl propionate, propyl propionate and difluoroethyl acetate;
(2) Based on 100 parts of the total mass of the electrolyte for the lithium ion battery, 1.5 to 15 parts of additive is prepared,
the additive consists of 0.1 to 10.0 parts of pyridine ring compound, 0.2 to 10.0 parts of sulfone group and nitrile group-containing compound and 1.0 to 14.5 parts of other additives;
(3) At room temperature, mixing 70-85 parts of organic solvent with 5-15 parts of lithium salt to obtain a mixture of the organic solvent and the lithium salt, and then adding 1.5-15 parts of additive to obtain electrolyte for the lithium ion battery;
the lithium salt comprises one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium bistrifluoromethanesulfonylimide, lithium bis (fluorosulfonyl) imide, lithium bis (oxalato) borate, lithium hexafluoroarsenate, lithium perchlorate and lithium trifluoromethanesulfonate.
5. A lithium ion battery comprising an electrolyte, a positive electrode sheet, a negative electrode sheet, and a separator, wherein the electrolyte is the electrolyte for a lithium ion battery according to any one of claims 1 to 3.
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| CN114552014A (en) * | 2022-02-25 | 2022-05-27 | 惠州锂威新能源科技有限公司 | Electrolyte and electrochemical device containing same |
| CN116053590A (en) * | 2023-03-28 | 2023-05-02 | 广汽埃安新能源汽车股份有限公司 | Lithium ion battery electrolyte, lithium ion battery and electric equipment |
| CN117728035A (en) * | 2024-02-18 | 2024-03-19 | 深圳海辰储能科技有限公司 | Electrolyte, secondary battery containing same, battery pack and electric equipment |
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| WO2011025016A1 (en) * | 2009-08-31 | 2011-03-03 | 三菱化学株式会社 | Non-aqueous electrolytic solution, and non-aqueous electrolyte battery comprising same |
| JP2017188299A (en) * | 2016-04-05 | 2017-10-12 | 旭化成株式会社 | Nonaqueous secondary battery, and nonaqueous electrolyte used therefor |
| CN107394258A (en) * | 2017-06-19 | 2017-11-24 | 华南师范大学 | A kind of high-voltage lithium-ion battery electrolyte and high-voltage lithium ion batteries |
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| KR101735857B1 (en) * | 2012-08-16 | 2017-05-24 | 삼성에스디아이 주식회사 | high voltage lithium rechargeable battery |
| CN105845977B (en) * | 2016-05-26 | 2018-12-21 | 宁德时代新能源科技股份有限公司 | Electrolyte and lithium ion battery comprising same |
| WO2018059484A1 (en) * | 2016-09-29 | 2018-04-05 | 比亚迪股份有限公司 | Anionic ionic liquid polymer, preparation method therefor and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2011025016A1 (en) * | 2009-08-31 | 2011-03-03 | 三菱化学株式会社 | Non-aqueous electrolytic solution, and non-aqueous electrolyte battery comprising same |
| JP2017188299A (en) * | 2016-04-05 | 2017-10-12 | 旭化成株式会社 | Nonaqueous secondary battery, and nonaqueous electrolyte used therefor |
| CN107394258A (en) * | 2017-06-19 | 2017-11-24 | 华南师范大学 | A kind of high-voltage lithium-ion battery electrolyte and high-voltage lithium ion batteries |
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