CN113964385B - Electrolyte, preparation method and application thereof - Google Patents
Electrolyte, preparation method and application thereof Download PDFInfo
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- CN113964385B CN113964385B CN202111217259.8A CN202111217259A CN113964385B CN 113964385 B CN113964385 B CN 113964385B CN 202111217259 A CN202111217259 A CN 202111217259A CN 113964385 B CN113964385 B CN 113964385B
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- lithium
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- carbonate
- lithium salt
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 145
- 238000002360 preparation method Methods 0.000 title abstract description 19
- 239000000654 additive Substances 0.000 claims abstract description 168
- 230000000996 additive effect Effects 0.000 claims abstract description 131
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 64
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 64
- -1 alkenyl silane Chemical compound 0.000 claims abstract description 55
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims abstract description 51
- 229910001416 lithium ion Inorganic materials 0.000 claims abstract description 51
- 238000002156 mixing Methods 0.000 claims abstract description 35
- 229910000077 silane Inorganic materials 0.000 claims abstract description 34
- 239000003125 aqueous solvent Substances 0.000 claims abstract description 31
- 239000002904 solvent Substances 0.000 claims abstract description 20
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 32
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 30
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 30
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 24
- 229910052744 lithium Inorganic materials 0.000 claims description 24
- 239000000203 mixture Substances 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 16
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 15
- 239000007774 positive electrode material Substances 0.000 claims description 15
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 14
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 13
- VEWLDLAARDMXSB-UHFFFAOYSA-N ethenyl sulfate;hydron Chemical compound OS(=O)(=O)OC=C VEWLDLAARDMXSB-UHFFFAOYSA-N 0.000 claims description 13
- DGTVXEHQMSJRPE-UHFFFAOYSA-M difluorophosphinate Chemical compound [O-]P(F)(F)=O DGTVXEHQMSJRPE-UHFFFAOYSA-M 0.000 claims description 12
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 239000007773 negative electrode material Substances 0.000 claims description 9
- 239000011888 foil Substances 0.000 claims description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 7
- 239000004698 Polyethylene Substances 0.000 claims description 7
- 150000001875 compounds Chemical class 0.000 claims description 7
- 239000011889 copper foil Substances 0.000 claims description 7
- 229920000573 polyethylene Polymers 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 150000005676 cyclic carbonates Chemical class 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 6
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 5
- 125000004122 cyclic group Chemical group 0.000 claims description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 4
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 3
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 claims description 3
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims description 3
- NDPGDHBNXZOBJS-UHFFFAOYSA-N aluminum lithium cobalt(2+) nickel(2+) oxygen(2-) Chemical compound [Li+].[O--].[O--].[O--].[O--].[Al+3].[Co++].[Ni++] NDPGDHBNXZOBJS-UHFFFAOYSA-N 0.000 claims description 3
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 3
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 3
- 229910021385 hard carbon Inorganic materials 0.000 claims description 3
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 claims description 3
- 229910002102 lithium manganese oxide Inorganic materials 0.000 claims description 3
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 claims description 3
- VLXXBCXTUVRROQ-UHFFFAOYSA-N lithium;oxido-oxo-(oxomanganiooxy)manganese Chemical compound [Li+].[O-][Mn](=O)O[Mn]=O VLXXBCXTUVRROQ-UHFFFAOYSA-N 0.000 claims description 3
- URIIGZKXFBNRAU-UHFFFAOYSA-N lithium;oxonickel Chemical compound [Li].[Ni]=O URIIGZKXFBNRAU-UHFFFAOYSA-N 0.000 claims description 3
- 229910021382 natural graphite Inorganic materials 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 229910021384 soft carbon Inorganic materials 0.000 claims description 3
- 239000008151 electrolyte solution Substances 0.000 claims 1
- 238000006116 polymerization reaction Methods 0.000 abstract description 7
- 230000001681 protective effect Effects 0.000 abstract description 7
- 230000003647 oxidation Effects 0.000 abstract description 3
- 238000007254 oxidation reaction Methods 0.000 abstract description 3
- 239000007784 solid electrolyte Substances 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 13
- 125000000217 alkyl group Chemical group 0.000 description 12
- 125000003342 alkenyl group Chemical group 0.000 description 11
- VOEUMFXKYRCDKK-UHFFFAOYSA-N FS(=N)F.FS(=N)F.[Li] Chemical compound FS(=N)F.FS(=N)F.[Li] VOEUMFXKYRCDKK-UHFFFAOYSA-N 0.000 description 10
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 7
- 239000002994 raw material Substances 0.000 description 6
- 230000014759 maintenance of location Effects 0.000 description 5
- 229910052759 nickel Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 3
- 239000006230 acetylene black Substances 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000002482 conductive additive Substances 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006864 oxidative decomposition reaction Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 150000008053 sultones Chemical class 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- PKRKCDBTXBGLKV-UHFFFAOYSA-N tris(ethenyl)-methylsilane Chemical compound C=C[Si](C)(C=C)C=C PKRKCDBTXBGLKV-UHFFFAOYSA-N 0.000 description 2
- 229920002554 vinyl polymer Polymers 0.000 description 2
- ZPFAVCIQZKRBGF-UHFFFAOYSA-N 1,3,2-dioxathiolane 2,2-dioxide Chemical compound O=S1(=O)OCCO1 ZPFAVCIQZKRBGF-UHFFFAOYSA-N 0.000 description 1
- DCBKFUVWBRFDDD-UHFFFAOYSA-N 4-fluoro-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile Chemical compound O1C(C)(C)C(C)(C)OB1C1=CC(C#N)=CC=C1F DCBKFUVWBRFDDD-UHFFFAOYSA-N 0.000 description 1
- 229910015872 LiNi0.8Co0.1Mn0.1O2 Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000002001 electrolyte material Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 description 1
- 125000001972 isopentyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 229920000609 methyl cellulose Polymers 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000001923 methylcellulose Substances 0.000 description 1
- 235000010981 methylcellulose Nutrition 0.000 description 1
- GRPIQKZLNSCFTB-UHFFFAOYSA-N n-[bis(dimethylamino)-fluoroimino-$l^{5}-phosphanyl]-n-methylmethanamine Chemical compound CN(C)P(=NF)(N(C)C)N(C)C GRPIQKZLNSCFTB-UHFFFAOYSA-N 0.000 description 1
- 125000004108 n-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000001280 n-hexyl group Chemical group C(CCCCC)* 0.000 description 1
- 125000000740 n-pentyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 125000004123 n-propyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])* 0.000 description 1
- 229910001453 nickel ion Inorganic materials 0.000 description 1
- 239000011356 non-aqueous organic solvent Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- HSFQBFMEWSTNOW-UHFFFAOYSA-N sodium;carbanide Chemical group [CH3-].[Na+] HSFQBFMEWSTNOW-UHFFFAOYSA-N 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- UFHILTCGAOPTOV-UHFFFAOYSA-N tetrakis(ethenyl)silane Chemical group C=C[Si](C=C)(C=C)C=C UFHILTCGAOPTOV-UHFFFAOYSA-N 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
Abstract
The invention provides an electrolyte, a preparation method and application thereof. The electrolyte includes a non-aqueous solvent, a lithium salt, and an additive, wherein the additive includes an alkenyl silane-containing additive. The invention also provides a preparation method of the electrolyte; and mixing the nonaqueous solvent, lithium salt and additives to obtain the electrolyte. According to the electrolyte provided by the invention, an oxidation polymerization reaction is carried out on the anode through the additive containing alkenyl silane, so that a compact solid electrolyte interface protective film is formed, and the electrolyte is inhibited from reacting with the anode; the lithium ion battery comprising the electrolyte has excellent high-temperature storage performance and rate performance.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to electrolyte, a preparation method and application thereof.
Background
The lithium ion battery has the advantages of high energy density, high working voltage, long cycle life, no memory effect and the like, is a main energy source of the current portable electronic equipment, and simultaneously shows good performance in the application fields of electric automobiles, intelligent Internet of things and the like.
To further accommodate the ever-evolving needs of applications, lithium ion batteries are required to have higher energy densities. Currently, there are two main schemes for improving the energy density of lithium ion batteries: the first scheme is to adopt a positive electrode material with high nickel element content; the second solution is to raise the charge cut-off voltage of the lithium ion battery. However, both of these solutions can have an adverse effect on the electrolyte. The stability of the positive electrode material is reduced due to the excessively high content of nickel element, and the electrolyte is subjected to oxidative decomposition in the positive electrode due to trivalent unstable nickel ions; on the other hand, increasing the battery charging voltage increases the positive electrode potential, and the electrolyte is also prone to oxidative decomposition, which causes a series of problems such as battery gassing and increased interface impedance. Thus, the art places more stringent demands on the electrolyte materials.
The prior art discloses a high-nickel ternary lithium ion power battery electrolyte and a high-nickel ternary lithium ion power battery. The electrolyte comprises a nonaqueous organic solvent, lithium salt, a conductive additive, a film-forming additive and an impregnating additive, wherein the conductive additive is lithium difluorophosphate, the film-forming additive is vinyl sulfate, and the impregnating additive is at least one of fluorophosphazene and fluoroethylene carbonate; through the synergistic effect and mutual promotion of the three additives, an excellent SEI film can be formed on the surface of the electrode, and each dynamic process in the lithium ion battery can be effectively promoted. However, the above does not take into account the interaction of the positive electrode material with the electrolyte, and the electrolyte is suitable for low-temperature and normal-temperature conditions, and is difficult to use in high-temperature conditions.
The prior art discloses an electrolyte for a high-nickel ternary positive electrode material system battery and a lithium ion battery. The electrolyte comprises a solvent, electrolyte lithium salt and an additive, wherein the additive comprises an anode film forming additive trivinyl methyl silane and a cathode film forming additive 5-cyano-2-fluorobenzeneboronic acid pinacol ester, so that the interface compatibility of the electrolyte and the anode and the cathode can be improved, and the cycle performance, high-low temperature performance and safety of the lithium ion battery are improved. However, the trivinylmethylsilane has low reactivity, and the stability of forming an SEI film needs to be further improved.
The common defects in the prior art are that the reaction between the positive electrode and the electrolyte is ignored or the activity of a positive electrode film forming additive in the electrolyte is low, and the formed SEI film has poor stability and is not suitable for high-temperature application, so that the performance of the lithium ion battery is affected.
Therefore, developing an electrolyte capable of forming a stable SEI film, protecting positive and negative electrode materials, thereby improving high temperature storage performance and safety performance of a lithium ion secondary battery is a problem to be solved in the art.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide an electrolyte, and a preparation method and application thereof. The electrolyte comprises a nonaqueous solvent, lithium salt and an additive; the additive includes an alkenylsilane-containing additive; the alkenyl silane-containing additive has the advantages that due to the existence of vinyl groups, oxidation polymerization reaction occurs at the positive electrode to form a compact Solid Electrolyte Interface (SEI) protective film, so that the reaction between electrolyte and a positive electrode material is inhibited, and the high-temperature storage performance of the lithium ion battery is improved.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides an electrolyte comprising a non-aqueous solvent, a lithium salt, and an additive, wherein the additive comprises an alkenylsilane-containing additive, and the alkenylsilane-containing additive comprises a compound having a structure represented by formula I or formula II,
wherein R is 1 、R 2 、R 3 、R 4 Each independently selected from Any one of R 0 、R 6 Each independently selected from any one of H, -ch=chr or C1 to C6 linear or branched alkyl, represents the attachment site of the group, and R, R 5 Each independently selected from H or C1 to C6 linear or branched alkyl, and wherein R 1 、R 2 、R 3 、R 4 Each independently selected from H or C1 to C6 linear or branched alkyl, X is selected from NR 0 、O、CH 2 Any one of, and R 0 A linear or branched alkyl group selected from H or C1 to C6.
In the invention, the additive of the electrolyte comprises an alkenyl silane-containing additive, the alkenyl silane-containing additive is subjected to oxidation polymerization reaction on the surface of the positive electrode to form a compact SEI film, the electrolyte is inhibited from reacting with the positive electrode material, the high-temperature storage performance and the safety performance of the lithium ion battery are improved, and the higher the electron cloud density of the vinyl in the alkenyl silane-containing additive, namely, the higher the reactivity of the alkenyl silane-containing additive is when the vinyl is connected with an electron donating group, the better the performance of the lithium ion battery comprising the electrolyte is.
The C1 to C6 linear or branched alkyl group includes C1, C2, C3, C4, C5 or C6 linear or branched alkyl groups; exemplary include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, n-hexyl, and the like.
As a preferred embodiment of the present invention, the alkenylsilane-containing additive includes any one or a combination of at least two of the following structural compounds:
wherein R is 1 、R 2 、R 3 、R 4 Each independently selected from H or a C1 to C6 linear or branched alkyl group.
Preferably, the alkenylsilane-containing additive comprises any one or a combination of at least two of the following compounds:
preferably, the electrolyte contains 0.05 to 15% by mass of the alkenylsilane additive, for example 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% etc.; preferably 0.05% to 5%.
In the invention, the mass percentage of the alkenyl silane-containing additive is less than 0.05 percent, and the lithium ion battery comprising the electrolyte has poor high-temperature storage performance; greater than 15%, the formed SEI film is thicker, resulting in an increase in internal resistance of the battery and a decrease in battery capacity.
Preferably, the additive further comprises other additives.
Preferably, the other additives include any one or a combination of at least two of a cyclic carbonate, a cyclic sultone, or a cyclic sulfate.
Preferably, the cyclic carbonate comprises any one or a combination of at least two of Vinylene Carbonate (VC), fluoroethylene carbonate (FEC) or ethylene carbonate (VEC).
Preferably, the cyclic sultone comprises 1, 3-Propane Sultone (PS) and/or 1, 3-Propenoic Sultone (PST).
Preferably, the cyclic sulfate comprises vinyl sulfate (DTD).
In the invention, the other additives form a compact SEI protective film on the negative electrode, inhibit the reaction of electrolyte and a negative electrode material, reduce the interface impedance of the negative electrode and improve the high-temperature storage performance and the multiplying power performance of the lithium ion battery.
Preferably, the mass percentage of the other additives in the electrolyte is 0.05% to 15%, for example, may be 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc.
In the invention, the mass percentage of the other additives is less than 0.05 percent, and a protective and compact SEI film cannot be formed on the surface of the negative electrode; greater than 15%, the SEI film formed is thicker, so that the impedance is greatly increased, and the conduction of lithium ions is hindered.
Preferably, the non-aqueous solvent includes any one or a combination of at least two of Ethylene Carbonate (EC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), propylene Carbonate (PC) or diethyl carbonate (DEC).
Preferably, the mass percentage of the nonaqueous solvent in the electrolyte is 60% to 85%, for example, 60%, 62%, 64%, 65%, 66%, 68%, 70%, 72%, 74%, 75%, 76%, 78%, 80%, 82%, 84%, 85%, etc.
Preferably, the non-aqueous solvent comprises a combination of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate.
Preferably, the mass ratio of the ethylene carbonate, the ethylmethyl carbonate and the diethyl carbonate is 1 (1 to 2): (0.1 to 1), and for example, may be 1:1:0.1, 1:1.2:0.2, 1:1.4:0.4, 1:1.6:0.6, 1:1.8:0.8, 1:2:1, etc.
Preferably, the lithium salt comprises lithium hexafluorophosphate (LiPF 6 )。
Preferably, the concentration of lithium hexafluorophosphate in the electrolyte is 0.5mol/L to 2mol/L, and may be, for example, 0.5mol/L, 0.6mol/L, 0.8mol/L, 1mol/L, 1.2mol/L, 1.4mol/L, 1.6mol/L, 1.8mol/L, 2mol/L, or the like.
Preferably, the lithium salt further comprises a lithium salt additive;
preferably, the lithium salt additive comprises lithium difluorophosphate (LiPO) 2 F 2 ) Any one or a combination of at least two of lithium bis (difluorosulfonimide) (LiFSI), lithium difluorooxalato borate (LiODFB), lithium bis (trifluoromethylsulfonimide) (LiTFSI) or lithium bis (oxalato difluorophosphate) (LiODFP).
In the invention, the electrolyte is used cooperatively by the lithium salt, the alkenyl silane-containing additive, other additives and the solvent, so that the lithium ion battery comprising the electrolyte has excellent rate capability and high-temperature storage capability.
Preferably, the mass percentage of the lithium salt additive in the electrolyte is 1% to 2%, for example, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc.
In a second aspect, the present invention provides a method for preparing the electrolyte according to the first aspect, the method comprising:
and mixing the nonaqueous solvent, lithium salt and the additive according to the formula amount to obtain the electrolyte.
Preferably, mixing a nonaqueous solvent, a lithium salt, and an additive to obtain the electrolyte comprises:
mixing 2 to 3 non-aqueous solvents, and then adding lithium salt into the mixture to obtain a mixed solution; and
and uniformly mixing the mixed solution with an additive to obtain the electrolyte.
In a third aspect, the present invention provides a lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, a separator and the electrolyte according to the first aspect.
Preferably, the positive electrode sheet includes an aluminum foil and a positive electrode active material coated on the aluminum foil.
Preferably, the positive electrode active material includes any one or a combination of at least two of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.
Preferably, the negative electrode tab includes a copper foil and a negative electrode active material coated on the copper foil.
Preferably, the negative electrode active material includes any one or a combination of at least two of soft carbon, hard carbon, artificial graphite, natural graphite, silicon, a silicon oxygen compound, a silicon carbon compound, or lithium titanate.
Preferably, the isolating film comprises a polyethylene membrane and nano alumina coated on the polyethylene membrane.
The numerical ranges recited herein include not only the recited point values, but also any point values between the recited numerical ranges that are not recited, and are limited to, and for the sake of brevity, the invention is not intended to be exhaustive of the specific point values that the recited range includes.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides an electrolyte comprising an alkenylsilane-containing additive; the alkenyl silane-containing additive is subjected to oxidative polymerization reaction at the positive electrode to form a compact SEI film, inhibit the reaction of electrolyte and a positive electrode material, and improve the high-temperature storage performance and the rate capability of the lithium ion battery; after the lithium ion battery comprising the electrolyte is stored for 30 days at 60 ℃, the thickness expansion rate of the battery is less than 23%, and the capacity retention rate is more than 82%.
Detailed Description
To facilitate understanding of the present invention, examples are set forth below. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
The scheme in the prior art is that the activity of the added negative electrode film forming additive or the added positive electrode film forming additive is low, and the formed SEI film has poor stability and is not suitable for high-temperature application, thereby influencing the performance of the lithium ion battery.
In order to solve the problems, the invention provides an electrolyte, a preparation method and application thereof, wherein the electrolyte comprises a nonaqueous solvent, lithium salt and an additive; the additive includes an alkenylsilane-containing additive; the electrolyte is subjected to oxidative polymerization reaction at the positive electrode through the alkenyl silane-containing additive to form a compact and stable SEI protective film, so that an electrode material is protected, and the high-temperature storage performance and the rate capability of the lithium ion battery are improved.
The alkenyl silane-containing additive comprises a compound with a structure shown in a formula I or a formula II,
wherein R is 1 、R 2 、R 3 、R 4 Each independently selected from Any one of R 0 、R 6 Each independently selected from any one of H, -ch=chr or C1 to C6 linear or branched alkyl, represents the attachment site of the group, and R, R 5 Each independently selected from H or C1 to C6 linear or branched alkyl, and wherein R 1 、R 2 、R 3 、R 4 Each independently selected from H or C1 to C6 linear or branched alkyl, X is selected from NR 0 、O、CH 2 Any one of, and R 0 A linear or branched alkyl group selected from H or C1 to C6.
In some embodiments, the alkenylsilane-containing additive includes any one or a combination of at least two of the following structural compounds:
wherein R is 1 、R 2 、R 3 、R 4 Each independently selected from H or a C1 to C6 linear or branched alkyl group.
In some embodiments, the alkenyl silane-containing additive comprises any one or a combination of at least two of the following compounds:
in some embodiments, the electrolyte contains an alkenylsilane additive in an amount of 0.05% to 15%, preferably 0.05% to 5% by mass.
In some embodiments, the additive further comprises other additives.
In some embodiments, the other additives include any one or a combination of at least two of a cyclic carbonate, a cyclic sultone, or a cyclic sulfate.
In some embodiments, the cyclic carbonate comprises any one or a combination of at least two of vinylene carbonate, fluoroethylene carbonate, or ethylene carbonate.
In some embodiments, the cyclic sultone comprises 1, 3-propane sultone and/or 1, 3-propenoic sultone.
In some embodiments, the cyclic sulfate comprises vinyl sulfate.
In some embodiments, the electrolyte comprises 0.05% to 15% by mass of other additives.
In some embodiments, the non-aqueous solvent comprises any one or a combination of at least two of ethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, propylene carbonate, or diethyl carbonate.
In some embodiments, the electrolyte comprises 60% to 85% by mass of non-aqueous solvent.
In some embodiments, the non-aqueous solvent comprises a combination of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate.
In some embodiments, the mass ratio of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate is 1 (1 to 2): 0.1 to 1.
In some embodiments, the lithium salt comprises lithium hexafluorophosphate.
In some embodiments, the concentration of lithium hexafluorophosphate in the electrolyte is 0.5mol/L to 2mol/L.
In some embodiments, the lithium salt further comprises a lithium salt additive.
In some embodiments, the lithium salt additive comprises any one or a combination of at least two of lithium difluorophosphate, lithium bis-difluorosulfonimide, lithium difluorooxalato borate, lithium bis-trifluoromethylsulfonimide, or lithium bis-oxalato difluorophosphate.
In some embodiments, the lithium salt additive is present in the electrolyte in an amount of 1% to 2% by mass.
The invention provides a preparation method of the electrolyte, which comprises the following steps:
and mixing the nonaqueous solvent, lithium salt and the additive according to the formula amount to obtain the electrolyte.
In some embodiments, mixing a non-aqueous solvent, a lithium salt, and an additive to obtain the electrolyte comprises:
mixing 2 to 3 non-aqueous solvents, and then adding lithium salt into the mixture to obtain a mixed solution; and
and uniformly mixing the mixed solution with an additive to obtain the electrolyte.
The invention provides a lithium ion battery, which comprises an anode plate, a cathode plate, a separation film and electrolyte.
In some embodiments, the positive electrode sheet includes an aluminum foil and a positive electrode active material coated on the aluminum foil.
In some embodiments, the positive electrode active material includes any one or a combination of at least two of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.
In some embodiments, the negative electrode tab includes a copper foil and a negative electrode active material coated on the copper foil.
In some embodiments, the negative electrode active material includes any one or a combination of at least two of soft carbon, hard carbon, artificial graphite, natural graphite, silicon, a silicon oxygen compound, a silicon carbon compound, or lithium titanate.
In some embodiments, the separator comprises a polyethylene separator and a nano alumina coated on the polyethylene separator.
The various materials used in the examples and comparative examples of the present invention are commercially available or may be prepared according to conventional methods in the art unless specifically stated otherwise. The mass percent (%) of the components in the examples and comparative examples was 100% based on the electrolyte.
Example 1
The embodiment provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 0.05% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 2
The embodiment provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 0.2% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 3
The present example provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 1% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 4
The embodiment provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 2.5% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 5
The embodiment provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 0.05% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives are prepared from ethylene sulfate, vinylene carbonate and 1, 3-propane sultone in mass ratioIs 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 6
The embodiment provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 0.2% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 7
The embodiment provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 0.4% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bis-difluorosulfimide and bis-fluorosulfonamideThe lithium difluorophosphate oxalate consists of the components in a mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 8
The embodiment provides an electrolyte comprising 1.8% lithium salt additive, 2.5% other additives, 2.5% alkenylsilane-containing additive, 1mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 9
The present example provides an electrolyte comprising 1% lithium salt additive, 0.05% other additives, 15% alkenylsilane additive, 0.5mol/L lithium hexafluorophosphate, the balance being a non-aqueous solvent; the non-aqueous solvent is prepared from carbonic acidVinyl ester, methyl ethyl carbonate and diethyl carbonate are formed according to the mass ratio of 1:2:1; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 10
The embodiment provides an electrolyte comprising 1% lithium salt additive, 15% other additives, 15% alkenylsilane additive, 2mol/L lithium hexafluorophosphate, and the balance being a non-aqueous solvent; the nonaqueous solvent consists of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the mass ratio of 1:1:0.5; the lithium salt additive consists of lithium difluorophosphate, lithium bisdifluorosulfimide and lithium bisoxalato difluorophosphate according to the mass ratio of 8:5:5; the other additives consist of vinyl sulfate, vinylene carbonate and 1, 3-propane sultone with the mass ratio of 2:1:2; the alkenyl-containing silane additive is
The embodiment provides a preparation method of the electrolyte, which specifically comprises the following steps:
and uniformly mixing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate according to the formula amount, adding lithium salt into the mixture, and uniformly mixing the mixture with an additive to obtain the electrolyte.
Example 11
This example provides an electrolyte which differs from example 1 only in that: the alkenylsilane-containing additive is tetravinylsilane, and other raw materials, proportions and mass percentage of each component are the same as those in example 1.
This example provides a method for preparing the electrolyte, and the specific steps are the same as in example 1.
Example 12
This example provides an electrolyte which differs from example 1 only in that: the electrolyte contains 25% of alkenyl silane additive by mass, and the non-aqueous solvent is adaptively adjusted to make the total amount of the electrolyte 100%, and other raw materials, proportions and mass percentages of all components are the same as those of the example 1.
This example provides a method for preparing the electrolyte, and the specific steps are the same as in example 1.
Example 13
This example provides an electrolyte which differs from example 5 only in that: the electrolyte contains 25% of alkenyl silane additive by mass, and the non-aqueous solvent is adaptively adjusted to make the total amount of the electrolyte 100%, and other raw materials, proportions and mass percentages of all components are the same as those of example 5.
This example provides a method for preparing the electrolyte, and the specific steps are the same as in example 5.
Example 14
This example provides an electrolyte which differs from example 1 only in that: the electrolyte is free of other additives, the balance is supplemented by a non-aqueous solvent, and other raw materials, proportions and mass percentages of all components are the same as those in the example 1.
This example provides a method for preparing the electrolyte, and the specific steps are the same as in example 1.
Comparative example 1
This comparative example provides an electrolyte which differs from example 1 only in that: the electrolyte contains no alkenyl silane additive, the balance is supplemented by a non-aqueous solvent, and other raw materials, proportions and mass percent of each component are the same as those in the example 1.
This comparative example provides a method for preparing the electrolyte, and the specific procedure is the same as in example 1.
Comparative example 2
This comparative example provides an electrolyte which differs from example 1 only in that: the electrolyte contains no alkenyl silane additive, the percentage of other additives in the electrolyte is 2.55%, and the mass percentage of other raw materials, the proportion and the components are the same as those in the example 1.
This comparative example provides a method for preparing the electrolyte, and the specific procedure is the same as in example 1.
Application example
The lithium ion battery comprises a positive pole piece, a negative pole piece, an isolating membrane and electrolyte; the electrolytes were the electrolytes provided in examples 1 to 14 and comparative examples 1 to 2, respectively; the preparation method of the lithium ion battery comprises the following steps:
obtaining the positive electrode plate: the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 The conductive agent acetylene black and the binder polyvinylidene fluoride are prepared from the following components in percentage by mass: 3:2, uniformly mixing the materials in N-methyl pyrrolidone, coating the mixture on an aluminum foil, drying and cold pressing the aluminum foil to obtain a positive electrode plate; the compaction density of the positive plate is 3.5g/cm 3 ；
Obtaining the negative electrode plate: the negative electrode active material graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber and the thickener sodium methyl cellulose are mixed according to the mass ratio of 96:2:1:1, uniformly mixing in water, coating on a copper foil, drying, and cold pressing to obtain the negative electrode plate, wherein the compacted density of the negative electrode plate is 1.65g/cm 3 ；
Obtaining the diaphragm: taking a polyethylene diaphragm with the thickness of 9 mu m as a base film, and coating a nano aluminum oxide coating with the thickness of 3 mu m on the base film to obtain the diaphragm;
obtaining the lithium ion battery: sequentially stacking the positive electrode plate, the diaphragm and the negative electrode plate to obtain a bare cell; and then the bare cell is put into an aluminum plastic film, dried at 80 ℃, injected with electrolyte and sealed, and the lithium ion battery is obtained through the procedures of standing, hot and cold pressing, formation, clamping, capacity division and the like. The performance test results of the lithium ion battery are shown in table 1.
Performance testing
(1) Thickness swelling change of the battery after 30 days of storage at 60 ℃): the lithium ion battery was charged to 4.2V at a constant current of 1C at 25C, then charged at a constant voltage to a current of 0.05C, and the thickness of the lithium ion battery before storage was measured and recorded as h 0 . Then the battery in full charge state is put into a baking oven at 60 ℃ for 30 days, and the thickness after the storage is tested and recorded as h 1 Calculating a thickness expansion rate with respect to the lithium ion battery before storage; thickness expansion rate (%) = (h) after 60 ℃/30 days storage 1 -h 0 )/h 0 ×100％。
(2) Capacity change of battery after 30 days of storage at 60 ℃): charging the lithium ion battery to 4.2V at a constant current of 1C at 25 ℃, then charging to a current of less than 0.05C at a constant voltage of 4.2V, then discharging to 3.0V at a constant current of 0.5C, testing the discharge capacity of the lithium ion battery at the moment and recording as D 0 The method comprises the steps of carrying out a first treatment on the surface of the Charging to 4.2V with 1C constant current, charging to current less than 0.05C with 4.2V constant voltage, storing the lithium ion battery at 60deg.C for 30 days, and discharging to 3.0V with 1C constant current after storage; then charging to 4.2V with 1C constant current, then charging to current less than 0.05C with 4.2V constant voltage, then discharging to 3.0V with 0.5C constant current, testing discharge capacity of lithium ion battery at this time and marking as D 1 . Each group was tested for 15 lithium ion batteries and averaged. Capacity retention (%) = (D) at 60 ℃/30 days 1 /D 0 )×100％。
The specific test results are shown in table 1:
TABLE 1
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As can be seen from the above table, the present invention provides an electrolyte comprising a non-aqueous solvent, a lithium salt and an additive; the additive comprises an alkenyl silane-containing additive, wherein the alkenyl silane-containing additive is subjected to oxidative polymerization reaction at the positive electrode to form an SEI protective film, so that the electrode material is protected from being damaged; the expansion rate of the thickness of the battery is less than 23% when the lithium ion battery containing the electrolyte is stored for 30 days at 60 ℃, the capacity retention rate is more than 82%, and as a preferable technical scheme of the invention, the expansion rate of the thickness of the battery containing the electrolyte is only less than 10% when the lithium ion battery containing the electrolyte is stored for 30 days at 60 ℃, the capacity retention rate is more than 90%, and both the high-temperature storage performance and the rate performance are improved.
Comparative examples 1 to 4, examples 5 to 8 show that the high temperature storage performance of the battery is improved and then reduced with the increase of the alkenylsilane-containing additive, indicating that the alkenylsilane-containing additive can exert the best effect when a certain amount is added; comparative examples 1 and 11 illustrate that the introduction of electron donating groups with increased electron cloud density to the alkenyl group can make it easier to undergo oxidative polymerization at the positive electrode to form a dense, well-protected SEI film; comparative examples 1 and 12, examples 5 and 13, demonstrate that an excessive addition of the alkenylsilane-containing additive results in a thicker SEI film for the battery with limited performance enhancement. As is evident from comparison of example 1 with comparative examples 1 and 2, when the electrolyte contains no alkenylsilane additive, the lithium ion battery has significantly reduced thickness expansion rate and capacity retention rate after 30 days of storage at 60 ℃.
In summary, the electrolyte provided by the invention adopts the alkenyl silane-containing additive to form the SEI protective film on the anode, so as to protect the anode material and improve the high-temperature storage performance of the lithium ion battery; and through the synergistic use of the alkenyl silane-containing additive, the lithium salt and other additives, the lithium ion battery containing the electrolyte is more excellent in performance, and the performance requirement of the lithium ion battery field on the electrolyte is met.
While the foregoing is directed to embodiments of the present invention, other and further details of the invention may be had by the present invention, it should be understood that the foregoing description is merely illustrative of the present invention and that no limitations are intended to the scope of the invention, except insofar as modifications, equivalents, improvements or modifications are within the spirit and principles of the invention.
Claims (20)
1. An electrolyte is characterized by comprising a non-aqueous solvent, lithium salt, a lithium salt additive, an alkenyl silane-containing additive and other additives,
the alkenyl silane-containing additive is selected from the following compounds:
the mass percentage of the alkenyl silane-containing additive in the electrolyte is 0.2 to 0.5 percent;
the other additives are a combination of cyclic carbonates, cyclic sultones and cyclic sulfates;
the mass percentage of other additives in the electrolyte is 1.5 to 2.5 percent.
2. The electrolyte of claim 1 wherein the cyclic carbonate comprises any one or a combination of at least two of vinylene carbonate, fluoroethylene carbonate or ethylene carbonate.
3. The electrolyte of claim 1 wherein the cyclic sultone comprises 1, 3-propane sultone and/or 1, 3-propenesulfontone.
4. The electrolyte of claim 1 wherein the cyclic sulfate comprises vinyl sulfate.
5. The electrolyte of claim 1 wherein the non-aqueous solvent comprises any one or a combination of at least two of ethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, propylene carbonate, or diethyl carbonate.
6. The electrolyte according to claim 1, wherein the non-aqueous solvent is present in the electrolyte in an amount of 60 to 85% by mass.
7. The electrolyte of claim 1 wherein the non-aqueous solvent comprises a combination of ethylene carbonate, ethylmethyl carbonate and diethyl carbonate.
8. The electrolyte according to claim 7, wherein the mass ratio of the ethylene carbonate, the ethylmethyl carbonate and the diethyl carbonate is 1: (1 to 2): (0.1 to 1).
9. The electrolyte of claim 1 wherein the lithium salt comprises lithium hexafluorophosphate.
10. The electrolyte of claim 1, wherein the concentration of lithium hexafluorophosphate in the electrolyte is 0.5mol/L to 2mol/L.
11. The electrolyte of claim 1, wherein the lithium salt additive comprises any one or a combination of at least two of lithium difluorophosphate, lithium bis-difluorosulfonimide, lithium difluorooxalato borate, lithium bis-trifluoromethylsulfonimide, or lithium bis-oxalato difluorophosphate.
12. The electrolyte according to claim 1, wherein the mass percentage of the lithium salt additive in the electrolyte is 1% to 2%.
13. A method of producing an electrolytic solution according to any one of claims 1 to 12, characterized in that the method comprises:
and mixing the nonaqueous solvent, lithium salt and the additive according to the formula amount to obtain the electrolyte.
14. The method of preparing according to claim 13, wherein mixing a nonaqueous solvent, a lithium salt, and an additive to obtain the electrolyte comprises:
mixing 2 to 3 non-aqueous solvents, and then adding lithium salt into the mixture to obtain a mixed solution; and
and uniformly mixing the mixed solution with an additive to obtain the electrolyte.
15. A lithium ion battery characterized in that it comprises a positive electrode sheet, a negative electrode sheet, a separator film and the electrolyte according to any one of claims 1 to 12.
16. The lithium ion battery of claim 15, wherein the positive electrode sheet comprises an aluminum foil and a positive electrode active material coated on the aluminum foil.
17. The lithium ion battery of claim 16, wherein the positive electrode active material comprises any one or a combination of at least two of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.
18. The lithium ion battery of claim 15, wherein the negative electrode tab comprises a copper foil and a negative electrode active material coated on the copper foil.
19. The lithium ion battery of claim 18, wherein the negative electrode active material comprises any one or a combination of at least two of soft carbon, hard carbon, artificial graphite, natural graphite, silicon, a silicon oxygen compound, a silicon carbon compound, or lithium titanate.
20. The lithium ion battery of claim 15, wherein the separator comprises a polyethylene separator and nano-alumina coated on the polyethylene separator.
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| US8273484B2 (en) * | 2005-05-26 | 2012-09-25 | Novolyte Technologies, Inc. | Nitrogen silylated compounds as additives in non-aqueous solutions for electrochemical cells |
| JP2016033918A (en) * | 2014-07-29 | 2016-03-10 | 富士フイルム株式会社 | All-solid type secondary battery, battery electrode sheet, method for manufacturing battery electrode sheet, solid electrolytic composition, method for manufacturing solid electrolytic composition, and method for manufacturing all-solid type secondary battery |
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