CN117276660A - Electrolyte additive, lithium ion battery electrolyte and lithium ion battery - Google Patents
Electrolyte additive, lithium ion battery electrolyte and lithium ion battery Download PDFInfo
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- CN117276660A CN117276660A CN202311039107.2A CN202311039107A CN117276660A CN 117276660 A CN117276660 A CN 117276660A CN 202311039107 A CN202311039107 A CN 202311039107A CN 117276660 A CN117276660 A CN 117276660A
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- electrolyte
- additive
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- lithium ion
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 57
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 57
- 239000003792 electrolyte Substances 0.000 title claims abstract description 39
- 239000002000 Electrolyte additive Substances 0.000 title claims abstract description 25
- 150000001875 compounds Chemical class 0.000 claims abstract description 31
- HTSGKJQDMSTCGS-UHFFFAOYSA-N 1,4-bis(4-chlorophenyl)-2-(4-methylphenyl)sulfonylbutane-1,4-dione Chemical compound C1=CC(C)=CC=C1S(=O)(=O)C(C(=O)C=1C=CC(Cl)=CC=1)CC(=O)C1=CC=C(Cl)C=C1 HTSGKJQDMSTCGS-UHFFFAOYSA-N 0.000 claims abstract description 27
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 16
- 125000005843 halogen group Chemical group 0.000 claims abstract description 8
- 125000002252 acyl group Chemical group 0.000 claims abstract description 6
- 229930195735 unsaturated hydrocarbon Natural products 0.000 claims abstract description 6
- 125000003545 alkoxy group Chemical group 0.000 claims abstract description 5
- 125000004093 cyano group Chemical group *C#N 0.000 claims abstract description 5
- 150000001335 aliphatic alkanes Chemical group 0.000 claims abstract description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims abstract description 3
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 claims abstract description 3
- 125000000542 sulfonic acid group Chemical group 0.000 claims abstract description 3
- 239000000654 additive Substances 0.000 claims description 49
- 230000000996 additive effect Effects 0.000 claims description 49
- 239000003960 organic solvent Substances 0.000 claims description 17
- 229910003002 lithium salt Inorganic materials 0.000 claims description 14
- 159000000002 lithium salts Chemical class 0.000 claims description 14
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 11
- 125000001153 fluoro group Chemical group F* 0.000 claims description 4
- 125000001183 hydrocarbyl group Chemical group 0.000 claims description 4
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 4
- 125000000217 alkyl group Chemical group 0.000 claims description 3
- ZPFAVCIQZKRBGF-UHFFFAOYSA-N 1,3,2-dioxathiolane 2,2-dioxide Chemical compound O=S1(=O)OCCO1 ZPFAVCIQZKRBGF-UHFFFAOYSA-N 0.000 claims description 2
- FALRKNHUBBKYCC-UHFFFAOYSA-N 2-(chloromethyl)pyridine-3-carbonitrile Chemical compound ClCC1=NC=CC=C1C#N FALRKNHUBBKYCC-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
- SJHAYVFVKRXMKG-UHFFFAOYSA-N 4-methyl-1,3,2-dioxathiolane 2-oxide Chemical compound CC1COS(=O)O1 SJHAYVFVKRXMKG-UHFFFAOYSA-N 0.000 claims description 2
- BTGRAWJCKBQKAO-UHFFFAOYSA-N adiponitrile Chemical compound N#CCCCCC#N BTGRAWJCKBQKAO-UHFFFAOYSA-N 0.000 claims description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 2
- 229910052731 fluorine Inorganic materials 0.000 claims description 2
- MGNVWUDMMXZUDI-UHFFFAOYSA-N propane-1,3-disulfonic acid Chemical compound OS(=O)(=O)CCCS(O)(=O)=O MGNVWUDMMXZUDI-UHFFFAOYSA-N 0.000 claims description 2
- 229940014800 succinic anhydride Drugs 0.000 claims description 2
- IAHFWCOBPZCAEA-UHFFFAOYSA-N succinonitrile Chemical compound N#CCCC#N IAHFWCOBPZCAEA-UHFFFAOYSA-N 0.000 claims description 2
- 238000003860 storage Methods 0.000 abstract description 18
- 239000007774 positive electrode material Substances 0.000 abstract description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 7
- 229910002804 graphite Inorganic materials 0.000 abstract description 7
- 239000010439 graphite Substances 0.000 abstract description 7
- 229910052723 transition metal Inorganic materials 0.000 abstract description 4
- 150000003624 transition metals Chemical class 0.000 abstract description 4
- 150000002430 hydrocarbons Chemical group 0.000 abstract 1
- 239000012266 salt solution Substances 0.000 description 11
- UHOPWFKONJYLCF-UHFFFAOYSA-N 2-(2-sulfanylethyl)isoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCS)C(=O)C2=C1 UHOPWFKONJYLCF-UHFFFAOYSA-N 0.000 description 7
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 7
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 210000004027 cell Anatomy 0.000 description 6
- 238000007600 charging Methods 0.000 description 6
- 229910052744 lithium Inorganic materials 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 230000006872 improvement Effects 0.000 description 5
- 230000014759 maintenance of location Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000007773 negative electrode material Substances 0.000 description 5
- 229910013872 LiPF Inorganic materials 0.000 description 4
- 101150058243 Lipf gene Proteins 0.000 description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 4
- 239000006258 conductive agent Substances 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- 125000000524 functional group Chemical group 0.000 description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000013538 functional additive Substances 0.000 description 3
- -1 lithium hexafluorophosphate Chemical compound 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 2
- 229910012820 LiCoO Inorganic materials 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
- 239000011230 binding agent Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000010280 constant potential charging Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000011363 dried mixture Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 125000001301 ethoxy group Chemical group [H]C([H])([H])C([H])([H])O* 0.000 description 2
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 description 2
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 125000002560 nitrile group Chemical group 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 description 1
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910013075 LiBF Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 150000007942 carboxylates Chemical class 0.000 description 1
- 150000001733 carboxylic acid esters Chemical class 0.000 description 1
- 150000005678 chain carbonates Chemical class 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 150000005676 cyclic carbonates Chemical class 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- FUZZWVXGSFPDMH-UHFFFAOYSA-M hexanoate Chemical compound CCCCCC([O-])=O FUZZWVXGSFPDMH-UHFFFAOYSA-M 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 150000002632 lipids Chemical class 0.000 description 1
- 239000011244 liquid electrolyte Substances 0.000 description 1
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 description 1
- 229910001486 lithium perchlorate Inorganic materials 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- 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 1
- 238000000034 method Methods 0.000 description 1
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 210000000352 storage cell Anatomy 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical group O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
- H01M10/0568—Liquid materials characterised by the solutes
-
- 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
- H01M10/0569—Liquid materials characterised by the solvents
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses an electrolyte additive, lithium ion battery electrolyte and a lithium ion battery. The electrolyte additive comprises a compound I with a structure shown in the following formula (1) and a compound II with a structure shown in the formula (2);
Description
Technical Field
The invention relates to the technical field of liquid electrolytes, in particular to an electrolyte additive, lithium ion battery electrolyte and a lithium ion battery.
Background
The lithium ion battery is widely applied to the fields of 3C electronic products, electric tools, energy storage power stations and the like due to the advantages of high energy density, wide use temperature range, long cycle life and the like. In addition, with the development of new energy automobiles and the improvement of the requirements for portable mobile electric equipment, the specific capacity requirement for lithium ion batteries is also higher and higher. In the prior art, high-voltage positive electrode materials are generally adopted to improve the specific capacity of the lithium ion battery, but even though the high-voltage positive electrode materials (such as lithium cobaltate) can influence the structural stability of the high-voltage positive electrode materials when the working voltage is more than 4.5V, so that transition metals in the positive electrode materials are dissolved out and reduced and deposited on the surface of a negative electrode, and the storage performance of the battery is deteriorated and the cycle stability is reduced. Moreover, the conventional electrolyte (carbonate electrolyte) is easy to decompose to generate gas under the conditions of high voltage and/or high temperature, so that the cycle stability of the battery is further reduced, the battery is expanded, and even safety problems are caused.
In order to solve the above problems, some functional additives are usually added to the electrolyte. For example, in the prior art, an electrolyte additive containing a phosphoric anhydride structure is disclosed, and the additive can form a protective film on the surface of a high-voltage ternary positive electrode material, so that the high-temperature storage performance of a battery is improved; for another example, in the prior art, an additive containing a double bond and a cyano structure is disclosed, and a protective substance can be formed on the surface of the positive electrode to improve the high-temperature storage performance of the battery; alternatively, the cycle performance of the battery is improved by adding a high-pressure film-forming additive. However, the improvement of the storage performance of the battery tends to be accompanied by an increase in the resistance thereof, which in turn leads to a decrease in the cycle performance thereof, i.e., it is difficult to achieve both the improvement of the storage performance and the cycle performance with the conventional electrolyte functional additives.
Disclosure of Invention
The invention aims to provide an electrolyte additive aiming at the defect and the defect that the existing electrolyte functional additive cannot improve the storage performance and the cycle performance of a battery at the same time.
It is yet another object of the present invention to provide a lithium ion battery electrolyte.
Another object of the present invention is to provide a lithium ion battery.
The above object of the present invention is achieved by the following technical scheme:
the invention provides an electrolyte additive, which comprises an additive a, wherein the additive a comprises a compound I with a structure shown in the following formula (1) and a compound II with a structure shown in the formula (2);
wherein R1, R2, R3, R4, R5, R6, R7 and R8 are each independently selected from one of H, a halogen atom, an alkane group having 1 to 10 carbon atoms, an unsaturated hydrocarbon group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkanoyl group having 2 to 10 carbon atoms and a phenyl group;
and H in the alkanyl, the unsaturated hydrocarbon group, the alkoxy group, and the alkanoyl group may be partially or entirely substituted with one or more of a halogen atom, a cyano group, a carboxyl group, and a sulfonic acid group.
The compound I in the electrolyte additive a takes a carbonyl group with larger activity as a main chain skeleton (C=O), and simultaneously introduces active functional groups (such as F atoms, methoxy groups, azomethyl groups and the like), so that the compound I not only has good lithium ion affinity, but also can generate smaller impedance, and can form a stable negative electrode interface film on the surface of a negative electrode material to effectively inhibit graphite peeling; the active functional groups of nitrile group (-CN), unsaturated double bond (-C=C) and ethoxy are introduced into the lipid main chain of the compound II in the additive a, and the nitrile group and the unsaturated double bond can induce to form a firm and stable CEI film on the surface of the positive electrode material so as to inhibit the dissolution of transition metal in the positive electrode material; and the ethoxy can provide lithium ion coordination, so that the viscosity of the additive is reduced, and the multiplying power and the cycle performance of the battery are improved. After the compound I and the compound II are combined, different specific active functional groups can interact, and meanwhile, the storage performance and the cycle performance of the battery under a high-voltage (4.53V) system are improved, and particularly, the battery has obvious improvement effects on the high-temperature storage performance, the high-temperature cycle performance and the multiplying power performance of the battery.
Preferably, in the compound I, R1, R2 and R3 are respectively halogen atoms, and R4 and R5 are respectively alkyl groups with 1-10 carbon atoms. More preferably, in the compound I, R1, R2 and R3 are each a fluorine atom, and R4 and R5 are each a methyl group. When R1, R2 and R3 are fluorine atoms, a LiF-rich anode interface film can be formed on the surface of the anode, so that graphite anode flaking is more effectively inhibited, and the rate performance, storage at high temperature and cycle performance of the battery are improved.
Preferably, R6, R7 and R8 in the compound II are alkyl groups with 1-10 carbon atoms respectively. More preferably, R6 in compound II is ethyl, and R7 and R8 are both methyl.
Specifically, compound I is
At least one of (a) and (b); compound II is At least one of them.
Specifically, the mass ratio of the compound I to the compound II is (0.5-3): 0.5-2; preferably, the mass ratio of the compound I to the compound II is (1.5-2): 1; more preferably, the mass ratio of compound I to compound II is 2:1.
Typically, the electrolyte additive further comprises an additive b which is one or more of ethylene carbonate, fluoroethylene carbonate, ethylene carbonate, 1, 3-propane sulfonate, propylene sulfite, ethylene sulfate, 4-methyl ethylene sulfate and, succinic anhydride, succinonitrile, adiponitrile and 1,3, 6-hexanetrinitrile. When the additive b and the additive a cooperate, a more uniform and compact SEI film with smaller impedance can be formed, and the storage performance, the cycle performance and the rate performance of the battery can be further improved.
Specifically, the mass ratio of the additive a to the additive b is (1.5-4): 15. Optionally, the mass ratio of additive a to additive b is 1.5:15, 2:15, 2.5:15, 3:15, 3.5:15, 4:15, but is not limited to the recited values, as other non-recited values within the range are equally applicable.
The invention also provides lithium ion battery electrolyte, which comprises lithium salt, organic solvent and the electrolyte additive.
In particular, the lithium salt may be lithium hexafluorophosphate (LiPF 6 ) Lithium perchlorate, lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (trifluoromethylsulfonyl) imide (LiN (SO) 2 CF 3 ) 2 ) Lithium bisoxalato borate (LiBOB), lithium difluorophosphate (LiPO) 2 F 2 ) Lithium difluorooxalato borate (LiODFB), lithium difluorodioxaato phosphate (LiPF) 2 (C 2 O 4 ) 2 ) And at least one of lithium bis-fluorosulfonyl imide.
The organic solvent is preferably at least one of a carbonate and a carboxylate, wherein the carbonate is a cyclic carbonate or a chain carbonate, optionally one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate and butylene carbonate; the carboxylic acid ester is one or more of butyl acetate, ethyl propionate and propyl propionate.
Specifically, the mass percentage of the electrolyte additive relative to the lithium ion battery electrolyte is 16.5-19%. Alternatively, the mass percentages are 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, but are not limited to the recited values, as other non-recited values within the range are equally applicable.
The lithium ion battery comprises a positive electrode plate, a negative electrode plate, a diaphragm positioned between the positive electrode plate and the negative electrode plate and the electrolyte of the lithium ion battery, and the lithium ion battery is also within the protection scope of the invention.
Specifically, the positive electrode material in the positive electrode sheet is lithium cobaltate or other high-voltage positive electrode materials; the negative electrode material in the negative electrode sheet is graphite, such as artificial graphite or natural graphite.
Compared with the prior art, the invention has the beneficial effects that:
the electrolyte additive combines the compound I with a specific structure with the compound II, and through different specific active functional group interactions, not only can form a stable negative electrode interface film on the surface of a negative electrode material to effectively inhibit graphite peeling, but also can induce a firm and stable CEI film on the surface of a positive electrode material to inhibit transition metal dissolution in the positive electrode material, and the two can cooperate to improve the storage performance and the cycle performance of the battery under a high-voltage system.
Detailed Description
The invention will be further described with reference to the following specific embodiments, but the examples are not intended to limit the invention in any way. Raw materials reagents used in the examples of the present invention are conventionally purchased raw materials reagents unless otherwise specified.
The conventional positive electrode plate and negative electrode plate in the art can be used in the invention, and for convenience in explanation of the technical effects of the invention, the following positive electrode plate (the positive electrode material is LiCoO) is specifically selected 2 ) And carrying out experiments on the negative electrode plate (the negative electrode material is commercial graphite).
Example 1
A lithium ion battery electrolyte is prepared by the following preparation method:
s1, in a glove box (O) filled with nitrogen 2 ＜2ppm，H 2 O < 3 ppm), the organic solvent is prepared from EC (ethylene carbonate), PC (propylene carbonate), DEC (diethyl carbonate) and PP (propyl propionate) according to the weight ratio of 15:10:10: 65;
s2, slowly adding LiPF into the organic solvent in S1 6 A lithium salt solution with a concentration of 1.2mol/L is prepared;
s3, mixing the lithium salt solution in S2, the organic solvent in S1, the compound I in the additive a, the compound II in the additive a and the additive b according to the weight ratio of 15:67:2:1:15, uniformly mixing to obtain the lithium ion battery electrolyte.
Wherein the structural formula of the compound I isCompound 2 has the structural formula
Example 2
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: in the step S3, the mass ratio of the lithium salt solution to the organic solvent to the compound I in the additive a to the compound II in the additive a to the additive b is 15:68.5:0.5:1:15.
example 3
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: in the step S3, the mass ratio of the lithium salt solution to the organic solvent to the compound I in the additive a to the compound II in the additive a to the additive b is 15:68:1:1:15.
example 4
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: in the step S3, the mass ratio of the lithium salt solution to the organic solvent to the compound I in the additive a to the compound II in the additive a to the additive b is 15:66:3:1:15.
example 5
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: in the step S3, the mass ratio of the lithium salt solution to the organic solvent to the compound I in the additive a to the compound II in the additive a to the additive b is 15:67.5:2:0.5:15.
example 6
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: in the step S3, the mass ratio of the lithium salt solution to the organic solvent to the compound I in the additive a to the compound II in the additive a to the additive b is 15:66:2:2:15.
example 7
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: the structural formula of the compound I in the additive a in the step S3 is
Example 8
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: the structural formula of the compound I in the additive a in the step S3 is
Example 9
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: the structural formula of the compound I in the additive a in the step S3 is
Example 10
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: the structural formula of the compound I in the additive a in the step S3 is
Example 11
A lithium ion battery electrolyte was prepared in substantially the same manner as in example 1, except that: the structural formula of the compound II in the additive a in the step S3 is
Example 12
Lithium ion battery electrolyte, preparation method and implementation thereofExample 1 is essentially the same, except that: the structural formula of the compound II in the additive a in the step S3 is
Comparative example 1
A lithium ion battery electrolyte is prepared by the following preparation method:
s1, in a glove box (O) filled with nitrogen 2 ＜2ppm，H 2 O < 3 ppm), the organic solvent is prepared from EC (ethylene carbonate), PC (propylene carbonate), DEC (diethyl carbonate) and PP (propyl propionate) according to the weight ratio of 15:10:10: 65;
s2, slowly adding LiPF into the organic solvent in S1 6 A lithium salt solution with a concentration of 1.2mol/L is prepared;
s3, mixing the lithium salt solution in S2, the organic solvent in S1, the compound II in the additive a and the additive b according to the weight ratio of 15:69:1:15, uniformly mixing to obtain the lithium ion battery electrolyte.
Comparative example 2
A lithium ion battery electrolyte is prepared by the following preparation method:
s1, in a glove box (O) filled with nitrogen 2 ＜2ppm，H 2 O < 3 ppm), the organic solvent is prepared from EC (ethylene carbonate), PC (propylene carbonate), DEC (diethyl carbonate) and PP (propyl propionate) according to the weight ratio of 15:10:10: 65;
s2, slowly adding LiPF into the organic solvent in S1 6 A lithium salt solution with a concentration of 1.2mol/L is prepared;
s3, mixing the lithium salt solution in S2, the organic solvent in S1, the compound I in the additive a and the additive b according to the weight ratio of 15:68:2:15, uniformly mixing to obtain the lithium ion battery electrolyte.
Performance testing
The lithium ion battery electrolytes in examples 1 to 12 and comparative examples 1 to 2 were assembled with a positive electrode sheet, a separator and a negative electrode sheet, respectively, to form a lithium ion battery, and the specific preparation method was as follows: and (3) carrying out lamination and winding on the positive electrode plate, the diaphragm and the negative electrode plate to obtain a bare cell, packaging and baking the bare cell through an aluminum plastic film, injecting the electrolyte into the lithium ion battery, and sequentially carrying out standing, formation, clamp shaping, secondary sealing and capacity testing to obtain the lithium ion battery.
The positive electrode plate is prepared by the following preparation method: the positive electrode material (4.53V high voltage LiCoO) 2 ) Dispersing a binder (polyvinylidene fluoride, PVDF) and a conductive agent (CNT) in N-methyl pyrrolidone (NMP) according to a mass ratio of 98:1:1, stirring in vacuum until the mixture is stable and uniform, uniformly coating the mixture on aluminum foil with the thickness of 10 mu m, airing the mixture at room temperature, transferring the dried mixture into a blast oven with the temperature of 120 ℃ for drying for 1 hour, and carrying out cold pressing and die cutting to obtain the positive electrode plate.
The negative electrode plate is prepared by the following preparation method: dispersing a negative electrode material (commercial graphite), a binder (polyvinylidene fluoride, PVDF) and a conductive agent (CNT) in a mass ratio of 97:2:1 in N-methylpyrrolidone (NMP), stirring in vacuum until the mixture is stable and uniform, uniformly coating the mixture on a copper foil with the thickness of 8 mu m, airing at room temperature, transferring the dried mixture into a blast oven with the temperature of 120 ℃ for drying for 1 hour, and carrying out cold pressing and die cutting to obtain the negative electrode plate.
The lithium ion battery prepared by the method is subjected to normal temperature/high temperature cycle test, multiplying power performance test and 60 ℃ high temperature storage performance test, the test results are shown in table 1, and the specific test method is as follows:
(1) Normal temperature (25 ℃)/high temperature (45 ℃) cycle test: placing the prepared lithium ion battery in an incubator for standing for 4 hours, then charging to 4.53V at constant current and constant voltage of 0.5C/0.05C, then discharging to 3.0V at constant current of 1C, and recording the initial capacity and the discharge capacity of the last circle (300/200 th circle) of the lithium ion battery in a circulating manner;
capacity retention (%) = discharge capacity of last round (300/200 th round) x 100% of initial capacity.
(2) And (3) multiplying power performance test: charging the lithium ion battery to 4.53V at a constant current of 0.5C in a 25 ℃ environment, charging the lithium ion battery to 0.02C at a constant voltage, and discharging the lithium ion battery to 3.0V at a constant current of 0.2C/1C/2C/3C/5C respectively, wherein the discharge capacity is recorded as the discharge capacity of the battery cell;
capacity retention (%) at different rates=discharge capacity at different rates/initial capacity of 0.2c×100%.
(3) High temperature storage test at 60 ℃): charging the lithium ion battery to 4.53V at a constant current of 0.5C in a 25 ℃ environment, charging the lithium ion battery to 0.02C at a constant voltage, discharging the lithium ion battery to 3.0V at a constant current of 0.2C, and recording the thickness, the internal resistance and the initial capacity of the battery core at the moment; then charging to 4.53V with constant current of 0.5C, placing in an oven with constant temperature of 60 ℃ for standing for 7 days, and measuring the thickness and internal resistance of the battery cell at the moment; the capacity discharged to 3.0V at 0.2C current was recorded as the residual capacity; and (3) carrying out constant-current charging on the stored battery core to 4.53V at a current of 0.5C, carrying out constant-voltage charging to a current of 0.02C, and then carrying out constant-current discharging to 3.0V at a current of 0.2C, wherein the capacity is recorded as the recovery capacity.
Capacity retention = remaining capacity/initial capacity x 100%;
capacity recovery rate = recovery capacity/initial capacity x 100%;
thickness expansion ratio= (cell thickness after storage-cell thickness before storage)/cell thickness before storage x 100%.
Table 1 properties of lithium ion battery electrolytes in examples and comparative examples
As can be seen from the data in table 1, the lithium ion battery added with the electrolyte additive of the invention has good capacity retention rate under the conditions of room temperature (25 ℃) or high temperature (45 ℃) and different multiplying power, namely has excellent cycle performance; and the capacity retention rate after being stored for 7 days at 60 ℃ reaches more than 75 percent, the capacity recovery rate reaches more than 80 percent, the thickness expansion rate is below 11%, namely, the film has excellent cycle performance. Meanwhile, it was found from examples 1, comparative examples 1 and 2 that the high-temperature storage performance and cycle performance of the battery can be effectively improved only when the compound I is used as an electrolyte additive in combination with the compound II; it is difficult to improve the high-temperature storage performance and cycle performance of the battery using either compound I or compound II alone.
The above examples of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (11)
1. An electrolyte additive, characterized by comprising an additive a comprising a compound I of the structure of formula (1) and a compound II of the structure of formula (2);
wherein R1, R2, R3, R4, R5, R6, R7 and R8 are each independently selected from one of H, a halogen atom, an alkane group having 1 to 10 carbon atoms, an unsaturated hydrocarbon group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkanoyl group having 2 to 10 carbon atoms and a phenyl group;
and H in the alkanyl, the unsaturated hydrocarbon group, the alkoxy group, and the alkanoyl group may be partially or entirely substituted with one or more of a halogen atom, a cyano group, a carboxyl group, and a sulfonic acid group.
2. The electrolyte additive according to claim 1, wherein R1, R2 and R3 in the compound I are each a halogen atom, and R4 and R5 are each an alkyl group having 1 to 10 carbon atoms.
3. The electrolyte additive according to claim 2, wherein R1, R2 and R3 in the compound I are each a fluorine atom, and R4 and R5 are each a methyl group.
4. The electrolyte additive according to claim 1, wherein R6, R7 and R8 in the compound II are each an alkane group having 1 to 10 carbon atoms.
5. The electrolyte additive according to claim 4, wherein R6 in the compound II is ethyl, and R7 and R8 are both methyl.
6. The electrolyte additive according to claim 1, wherein the mass ratio of the compound I to the compound II is (0.5 to 3): 0.5 to 2.
7. The electrolyte additive according to any one of claims 1 to 6, further comprising an additive b which is one or more of ethylene carbonate, fluoroethylene carbonate, ethylene carbonate, 1, 3-propane sulfonate, propylene sulfite, ethylene sulfate, 4-methyl sulfate and succinic anhydride, succinonitrile, adiponitrile and 1,3, 6-hexanetrinitrile.
8. The electrolyte additive according to claim 7, wherein the mass ratio of the additive a to the additive b is (1.5-4): 15.
9. A lithium ion battery electrolyte comprising a lithium salt, an organic solvent and an additive, wherein the additive is the electrolyte additive of any one of claims 1-8.
10. The lithium ion battery electrolyte according to claim 9, wherein the mass percentage of the additive relative to the lithium ion battery electrolyte is 16.5% -19%.
11. A lithium ion battery comprising a positive electrode plate, a negative electrode plate, a diaphragm positioned between the positive electrode plate and the negative electrode plate and electrolyte, wherein the electrolyte is the lithium ion battery electrolyte as claimed in claim 9 or 10.
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