CN113270644A - Electrolyte and preparation method and application thereof - Google Patents
Electrolyte and preparation method and application thereof Download PDFInfo
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- CN113270644A CN113270644A CN202110534984.1A CN202110534984A CN113270644A CN 113270644 A CN113270644 A CN 113270644A CN 202110534984 A CN202110534984 A CN 202110534984A CN 113270644 A CN113270644 A CN 113270644A
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 145
- 238000002360 preparation method Methods 0.000 title abstract description 21
- RAXXELZNTBOGNW-UHFFFAOYSA-N imidazole Natural products C1=CNC=N1 RAXXELZNTBOGNW-UHFFFAOYSA-N 0.000 claims abstract description 48
- 239000002608 ionic liquid Substances 0.000 claims abstract description 43
- 239000003960 organic solvent Substances 0.000 claims abstract description 31
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 28
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 28
- 150000002460 imidazoles Chemical class 0.000 claims abstract description 24
- JDZCKJOXGCMJGS-UHFFFAOYSA-N [Li].[S] Chemical compound [Li].[S] JDZCKJOXGCMJGS-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 6
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims abstract description 6
- 125000003545 alkoxy group Chemical group 0.000 claims abstract description 5
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 5
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 28
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 25
- WNXJIVFYUVYPPR-UHFFFAOYSA-N 1,3-dioxolane Chemical compound C1COCO1 WNXJIVFYUVYPPR-UHFFFAOYSA-N 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 9
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 8
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 8
- LRESCJAINPKJTO-UHFFFAOYSA-N bis(trifluoromethylsulfonyl)azanide;1-ethyl-3-methylimidazol-3-ium Chemical class CCN1C=C[N+](C)=C1.FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F LRESCJAINPKJTO-UHFFFAOYSA-N 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 5
- XNWFRZJHXBZDAG-UHFFFAOYSA-N 2-METHOXYETHANOL Chemical compound COCCO XNWFRZJHXBZDAG-UHFFFAOYSA-N 0.000 claims description 4
- JWUJQDFVADABEY-UHFFFAOYSA-N 2-methyltetrahydrofuran Chemical compound CC1CCCO1 JWUJQDFVADABEY-UHFFFAOYSA-N 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 4
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims description 4
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 4
- LCGLNKUTAGEVQW-UHFFFAOYSA-N methyl monoether Natural products COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 11
- 229910001416 lithium ion Inorganic materials 0.000 description 11
- 239000002904 solvent Substances 0.000 description 10
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 6
- 238000011056 performance test Methods 0.000 description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 239000008151 electrolyte solution Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 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 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 238000007614 solvation Methods 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- JHRWWRDRBPCWTF-OLQVQODUSA-N captafol Chemical compound C1C=CC[C@H]2C(=O)N(SC(Cl)(Cl)C(Cl)Cl)C(=O)[C@H]21 JHRWWRDRBPCWTF-OLQVQODUSA-N 0.000 description 1
- 150000001733 carboxylic acid esters Chemical class 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 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
- 150000002148 esters Chemical class 0.000 description 1
- 150000002170 ethers Chemical class 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
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000011244 liquid electrolyte Substances 0.000 description 1
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000005677 organic carbonates Chemical class 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- 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)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
Abstract
The invention provides an electrolyte and a preparation method and application thereof. The electrolyte comprises lithium salt, an organic solvent and an ionic liquid; the ionic liquid is selected from alkyl substituted imidazole ionic liquid and/or alkoxy substituted imidazole ionic liquid. The preparation method comprises the following steps: and mixing lithium salt, an organic solvent and ionic liquid to obtain the electrolyte. The electrolyte provided by the invention has higher conductivity and better cycle performance, and is suitable for being used as the electrolyte of lithium-sulfur batteries, lithium-iron phosphate batteries and other lithium secondary batteries.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an electrolyte and a preparation method and application thereof.
Background
With the development of society, energy problems become a major problem that needs to be considered in human society, and electrochemical technology plays an important role in solving the energy problems. Among many energy conversion and storage devices, lithium ion batteries have been successfully commercialized and widely used in various fields of daily life by virtue of their advantages of high operating voltage, high energy density, low self-discharge rate, long cycle life, no memory effect, and the like.
At present, commercial lithium ion battery electrolyte is mainly a mixed solution of an organic carbonate solvent and lithium salt, carbonate substances are volatile and have low flash points, the use safety of the lithium ion battery under special conditions such as high temperature and overcharge cannot be guaranteed, the concentration of the lithium salt in the electrolyte is generally lower than 1-1.5 mol/L, and although the liquid electrolyte is widely applied, the electrolyte is easy to decompose under high voltage, so that the charge-discharge efficiency of the lithium battery is lower and the cycle performance of the lithium battery is poor.
Different from the situation that a large number of free solvent molecules and anions exist in a low-concentration electrolyte, in a high-concentration electrolyte (the concentration of lithium salt is more than 3mol/L), the solvent molecules and the anions almost participate in the solvation of lithium ions, so that a special solvation structure is formed, and the electrolyte has some outstanding performances. Firstly, the reaction activity of the electrolyte is obviously reduced, which is beneficial to inhibiting the carbonate electrolyte from being oxidized under higher voltage, and meanwhile, the carbonate electrolyte can be prevented from being reduced under lower voltage, so that the method is an effective measure for obtaining the electrolyte with good stability of the counter electrode; secondly, the high-concentration electrolyte also contributes to the inhibition of corrosion of aluminum foil by a sulfonimide-based electrolyte represented by lithium bistrifluoromethylsulfonimide (LiTFSI); thirdly, the flammable solvent molecules in the high-concentration electrolyte are less, and the flammability of the electrolyte is reduced; fourthly, solvent molecules in the high-concentration electrolyte have strong binding force with lithium ions, so that the solvent is not easy to volatilize, and the thermal stability of the electrolyte is obviously improved; fifthly, the high-concentration electrolyte is helpful for inhibiting the growth of metal lithium dendrites, but the proportion of lithium salt in the electrolyte is too high, so that the viscosity of the electrolyte is obviously increased, the activity of lithium ions is reduced, the conductivity of the electrolyte is obviously reduced, and good wetting between the electrolyte and an electrode is also not facilitated.
For example, CN108270035B discloses a battery electrolyte containing a high concentration of lithium salt. The electrolyte contains lithium salt, a fluoro solvent and an organic solvent, and the molar concentration of the lithium salt in the electrolyte is higher than 3 mol/L; the mass fraction of the fluorinated solvent in the electrolyte is 5-90%, the mass fraction of the organic solvent in the electrolyte is 20-98%, and the organic solvent is at least one selected from cyclic carbonate compounds, chain carbonate compounds, ether compounds and carboxylic esters. CN106816633A discloses a high-concentration ester lithium-sulfur battery electrolyte and a lithium-sulfur battery. The electrolyte contains a battery electrolyte of lithium salt, an ester solvent and a non-solvent solution, wherein the concentration of the lithium salt in the ether solvent is higher than 3.0mol/L, and the overall concentration of the lithium salt in the pseudo high-concentration electrolyte is not lower than 0.5 mol/L. Although the concentration of the lithium salt in the battery electrolyte provided by the technical scheme is higher, the viscosity of the battery electrolyte is higher, the conductivity is lower, and the battery electrolyte is not suitable for practical use.
Therefore, how to provide a lithium ion battery electrolyte with higher lithium salt concentration and higher conductivity has become a technical problem to be solved urgently at present.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide an electrolyte and a preparation method and application thereof. According to the invention, through the design of the components of the electrolyte and further adopting the alkyl substituted imidazole ionic liquid and/or the alkoxy substituted imidazole ionic liquid, the prepared electrolyte has higher conductivity and better cycle performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides an electrolyte comprising a lithium salt, an organic solvent and an ionic liquid;
the ionic liquid is selected from alkyl substituted imidazole ionic liquid and/or alkoxy substituted imidazole ionic liquid.
According to the invention, through the design of the components of the electrolyte and further adopting the alkyl substituted imidazole ionic liquid and/or the alkoxy substituted imidazole ionic liquid, the prepared electrolyte has higher conductivity and better cycle performance.
In the invention, the electrolyte prepared from the alkyl-substituted imidazole ionic liquid and/or the alkoxy-substituted imidazole ionic liquid has a viscosity suitable for use and a high lithium ion conductivity, and the lithium ion battery prepared by the electrolyte has excellent cycle performance.
The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the object and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.
In a preferred embodiment of the present invention, the lithium salt is selected from any one or a combination of at least two of lithium bis (fluorosulfonyl) imide, lithium hexafluorophosphate, lithium bis (trifluoromethylsulfonyl) imide, and lithium tetrafluoroborate.
In a preferred embodiment of the present invention, the lithium salt in the electrolyte solution is 20 to 40% by mass, for example, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, or 40%.
In the invention, the content of the lithium salt in the electrolyte is controlled within a specific range, so that the prepared electrolyte has excellent electrochemical performance. If the content of lithium salt in the electrolyte is too low, the prepared electrolyte has poor cycle performance; if the content of lithium salt in the electrolyte is too much, the prepared electrolyte has high viscosity and low conductivity.
In a preferred embodiment of the present invention, the organic solvent includes a combination of an organic solvent a and an organic solvent B.
According to the invention, the organic solvent A is used for dissociating lithium salt to form lithium ions, and the organic solvent B can effectively reduce the viscosity of the electrolyte.
Preferably, the organic solvent A is selected from any one or a combination of at least two of dioxolane, tetrahydrofuran or 2-methyltetrahydrofuran.
Preferably, the content of the organic solvent a in the electrolyte solution is 5 to 20% by mass, and may be, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or the like.
In the invention, by controlling the mass percentage of the organic solvent A within a specific range, the lithium salt can be fully dissociated, and the prepared electrolyte has better safety. If the mass percentage of the organic solvent A is smaller, the lithium salt cannot be fully dissociated, and the electrochemical performance of the prepared electrolyte is poorer; if the mass percentage content of the organic solvent A is larger, the prepared electrolyte can generate gas, so that the safety of the electrolyte is poorer.
Preferably, the organic solvent B is selected from any one of or a combination of at least two of ethylene glycol dimethyl ether, methyl glycol dimethyl ether or diethylene glycol dimethyl ether.
Preferably, the content of the organic solvent B in the electrolyte is 20 to 45% by mass, and may be, for example, 20%, 22%, 25%, 27%, 30%, 33%, 35%, 28%, 40%, 42%, 45%, or the like.
In a preferred embodiment of the present invention, the ionic liquid is selected from any one or a combination of at least two of 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl ether-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt, and 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt.
In a preferred embodiment of the present invention, the ionic liquid in the electrolyte solution is 10 to 30% by mass, for example, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or the like.
In the invention, the electrolyte has better circulation performance and higher conductivity by controlling the concentration of the ionic liquid within a specific range. If the content of the ionic liquid is too low, the prepared electrolyte has poor cycle performance; if the content of the ionic liquid is too much, the prepared electrolyte has high viscosity, low conductivity and poor cycle performance.
In a second aspect, the present invention provides a method for preparing the electrolyte according to the first aspect, the method comprising:
and mixing lithium salt, an organic solvent and ionic liquid to obtain the electrolyte.
In a preferred embodiment of the present invention, the mixing temperature is 15 to 40 ℃, and may be, for example, 15 ℃, 17 ℃, 20 ℃, 22 ℃, 25 ℃, 27 ℃, 30 ℃, 33 ℃, 35 ℃, 38 ℃ or 40 ℃.
In a preferred embodiment of the present invention, the mixing is performed in the presence of an inert gas.
Preferably, the inert gas is selected from nitrogen and/or argon.
In the invention, the electrolyte is prepared in the presence of inert gas to avoid the contact of moisture and oxygen with the electrolyte solution and the side reaction of the electrolyte.
In a third aspect, the invention provides a use of the electrolyte according to the first aspect in a lithium sulphur battery or a lithium iron phosphate battery.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, through the design of the components of the electrolyte, alkyl-substituted imidazole ionic liquid and/or alkoxy-substituted imidazole ionic liquid are further adopted and the content of the alkyl-substituted imidazole ionic liquid and/or alkoxy-substituted imidazole ionic liquid is controlled within a specific range, the prepared electrolyte has high conductivity, good cycle performance and low viscosity, the conductivity is 6.93-11.24S/cm, the viscosity is 2.2-4.5 cP, the cycle performance test of more than 200 circles can be completed under the charge-discharge rate of 0.1C, and the electrolyte is suitable for being used as the electrolyte of secondary batteries such as lithium-sulfur batteries, lithium-iron phosphate batteries and the like.
Detailed Description
The technical scheme of the invention is further illustrated by the following specific examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides an electrolyte and a preparation method thereof, wherein the electrolyte comprises the following components in percentage by mass: 30% of lithium bis (fluorosulfonyl) imide, 17% of dioxolane, 35% of ethylene glycol dimethyl ether and 18% of 1-butyl-3-methylimidazolium hexafluorophosphate.
The preparation method of the electrolyte comprises the following steps:
in the presence of nitrogen, lithium bis (fluorosulfonyl) imide, dioxolane, ethylene glycol dimethyl ether and 1-butyl-3-methylimidazole hexafluorophosphate are uniformly mixed at 20 ℃ to obtain the electrolyte.
Example 2
The embodiment provides an electrolyte and a preparation method thereof, wherein the electrolyte comprises the following components in percentage by mass: lithium hexafluorophosphate 20%, tetrahydrofuran 5%, methyl glycol dimethyl ether 45% and 1-ethyl ether-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt 30%.
The preparation method of the electrolyte comprises the following steps:
in the presence of argon, lithium hexafluorophosphate, tetrahydrofuran, methyl glycol dimethyl ether and 1-ethyl ether-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt are uniformly mixed at 15 ℃ to obtain the electrolyte.
Example 3
The embodiment provides an electrolyte and a preparation method thereof, wherein the electrolyte comprises the following components in percentage by mass: lithium bis (trifluoromethanesulfonyl) imide 40%, 2-methyltetrahydrofuran 20%, diglyme 20%, and 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt 20%.
The preparation method of the electrolyte comprises the following steps:
in the presence of nitrogen, lithium bis (trifluoromethylsulfonyl) imide, 2-methyltetrahydrofuran, diglyme and 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt are uniformly mixed at 30 ℃ to obtain the electrolyte.
Example 4
The embodiment provides an electrolyte and a preparation method thereof, wherein the electrolyte comprises the following components in percentage by mass: lithium tetrafluoroborate 25%, dioxolane 15%, ethylene glycol dimethyl ether 38%, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt 10% and 1-ethylethylether-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt 12%.
The preparation method of the electrolyte comprises the following steps:
in the presence of argon, lithium tetrafluoroborate, dioxolane, ethylene glycol dimethyl ether, 1-ethyl ether-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt and 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt are uniformly mixed at 40 ℃ to obtain the electrolyte.
Example 5
The embodiment provides an electrolyte and a preparation method thereof, and the difference from the embodiment 1 is that the electrolyte comprises the following components in percentage by mass: 30% of lithium bis (fluorosulfonyl) imide, 20% of dioxolane, 40% of ethylene glycol dimethyl ether and 10% of 1-butyl-3-methylimidazole hexafluorophosphate; other conditions were the same as in example 1.
Example 6
The embodiment provides an electrolyte and a preparation method thereof, and the difference from the embodiment 1 is that the electrolyte comprises the following components in percentage by mass: 30% of lithium bis (fluorosulfonyl) imide, 13% of dioxolane, 27% of ethylene glycol dimethyl ether and 30% of 1-butyl-3-methylimidazole hexafluorophosphate; other conditions were the same as in example 1.
Example 7
The embodiment provides an electrolyte and a preparation method thereof, and the difference from the embodiment 1 is that the electrolyte comprises the following components in percentage by mass: 30% of lithium bis (fluorosulfonyl) imide, 21% of dioxolane, 42% of ethylene glycol dimethyl ether and 7% of 1-butyl-3-methylimidazolium hexafluorophosphate; other conditions were the same as in example 1.
Example 8
The embodiment provides an electrolyte and a preparation method thereof, and the difference from the embodiment 1 is that the electrolyte comprises the following components in percentage by mass: 11.5% of lithium bis (fluorosulfonyl) imide, 16% of dioxolane, 23.5% of ethylene glycol dimethyl ether and 35% of 1-butyl-3-methylimidazolium hexafluorophosphate; other conditions were the same as in example 1.
Example 9
The embodiment provides an electrolyte and a preparation method thereof, and the difference from the embodiment 1 is only that the electrolyte does not contain dioxolane, and the mass percentage of glycol dimethyl ether is 52%; other conditions were the same as in example 1.
Example 10
The embodiment provides an electrolyte and a preparation method thereof, and the difference from the embodiment 1 is only that the electrolyte does not contain ethylene glycol dimethyl ether, and the mass percentage of dioxolane is 52%; other conditions were the same as in example 1.
Example 11
The embodiment provides an electrolyte and a preparation method thereof, and the difference from the embodiment 1 is that the electrolyte comprises the following components in percentage by mass: 30% of lithium bis (fluorosulfonyl) imide, 32% of dimethyl carbonate, 20% of ethylene carbonate and 18% of 1-butyl-3-methylimidazolium hexafluorophosphate; other conditions were the same as in example 1.
Comparative example 1
This comparative example provides an electrolyte and a method for preparing the same, which are different from example 1 in that 1-butyl-3-methylimidazolium hexafluorophosphate is replaced with N-propyl-N-methylpyrrolidine bis (trifluoromethanesulfonyl) imide salt; other conditions were the same as in example 1.
The performance of the electrolytes provided in the above examples and comparative examples was tested according to the following test criteria:
(1) conductivity: testing in a drying room (dew point is minus 50 ℃ and temperature is 20 ℃) by using a conductivity tester;
(2) cycle performance: the electrolyte provided by the embodiment and the comparative example is assembled into a CR2025 battery by taking polyacrylonitrile sulfur and nickel cobalt lithium manganate as positive electrode materials, and a cycle performance test is carried out under the charge-discharge rate of 0.1C to test the number of cycles that the battery can complete, wherein each group of experiments is tested for ten times.
(3) Viscosity: the test is carried out in a drying room (dew point is minus 50 ℃ and the temperature is 20 ℃) by using a viscosity tester.
The electrolyte provided by the above examples and comparative examples has the following performance test results as shown in table 1 below:
TABLE 1
As can be seen from Table 1, by designing the components of the electrolyte, the alkyl-substituted imidazole ionic liquid and/or the alkoxy-substituted imidazole ionic liquid are further adopted, and the content of the alkyl-substituted imidazole ionic liquid and/or the alkoxy-substituted imidazole ionic liquid is controlled within a specific range, so that the prepared electrolyte has high conductivity, good cycle performance and low viscosity, the conductivity is 6.93-11.24S/cm, the viscosity is 2.2-4.5 cP, and the cycle performance test of more than 200 circles can be completed under the charge-discharge multiplying power of 0.1C, so that the electrolyte is suitable for being used as the electrolyte of secondary batteries such as lithium-sulfur batteries, lithium-iron phosphate batteries and the like.
Compared with the example 1, if the content of the ionic liquid in the electrolyte is small (example 7), the prepared electrolyte has poor cycle performance, and the cycle performance test of 102-150 circles can be completed only under the charge-discharge rate of 0.1C; if the content of the ionic liquid in the electrolyte is large (example 8), the viscosity of the prepared electrolyte is large 6.4cP, the conductivity is low 4.35S/cm, and the cycle performance is poor. Therefore, the content of the ionic liquid in the electrolyte has a crucial influence on the viscosity, the conductivity and the cycle performance of the electrolyte.
Compared with example 1, if the electrolyte does not contain dioxolane (example 9), the prepared electrolyte has poor cycle performance; if the electrolyte does not contain ethylene glycol dimethyl ether (example 10), the viscosity of the prepared electrolyte is higher than 8.2cP, the conductivity is lower than 0.64S/cm, and the cycle performance is poor. Therefore, the electrolyte prepared by the invention has higher conductivity, better cycle performance and lower viscosity by matching the two organic solvents.
Compared with example 1, if the organic solvent in the electrolyte is a carbonate organic solvent (example 11), the prepared electrolyte has poor cycle performance; if 1-butyl-3-methylimidazolium hexafluorophosphate is replaced with N-butyl-N-methylpyrrolidine bis (trifluoromethanesulfonyl) imide salt (comparative example 1), the prepared electrolyte has poor cycle performance. Therefore, the electrolyte has better cycle performance through the design of the components of the electrolyte.
In summary, by designing the components of the electrolyte, the alkyl-substituted imidazole ionic liquid and/or the alkoxy-substituted imidazole ionic liquid are/is further adopted and the content of the alkyl-substituted imidazole ionic liquid and/or the alkoxy-substituted imidazole ionic liquid is controlled within a specific range, so that the prepared electrolyte has high conductivity, good cycle performance and low viscosity, and is suitable for being used as electrolytes of secondary batteries such as lithium-sulfur batteries, lithium-iron phosphate batteries and the like.
The applicant states that the present invention is illustrated by the detailed process flow of the present invention through the above examples, but the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. An electrolyte, characterized in that the electrolyte comprises a lithium salt, an organic solvent and an ionic liquid;
the ionic liquid is selected from alkyl substituted imidazole ionic liquid and/or alkoxy substituted imidazole ionic liquid.
2. The electrolyte of claim 1, wherein the lithium salt is selected from any one of or a combination of at least two of lithium bis-fluorosulfonylimide, lithium hexafluorophosphate, lithium bis-trifluoromethylsulfonyl imide, or lithium tetrafluoroborate.
3. The electrolyte according to claim 1 or 2, wherein the lithium salt is 20-40% by mass of the electrolyte.
4. The electrolyte of any one of claims 1-3, wherein the organic solvent comprises a combination of organic solvent A and organic solvent B;
preferably, the organic solvent A is selected from any one or a combination of at least two of dioxolane, tetrahydrofuran or 2-methyltetrahydrofuran;
preferably, the mass percentage of the organic solvent A in the electrolyte is 5-20%;
preferably, the organic solvent B is selected from any one or a combination of at least two of ethylene glycol dimethyl ether, methyl glycol dimethyl ether or diethylene glycol dimethyl ether;
preferably, the mass percentage of the organic solvent B in the electrolyte is 20-45%.
5. The electrolyte of any one of claims 1 to 4, wherein the ionic liquid is selected from any one of or a combination of at least two of 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl ether-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt, or 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt.
6. The electrolyte according to any one of claims 1 to 5, wherein the ionic liquid is contained in the electrolyte in an amount of 10 to 30% by mass.
7. A method for preparing the electrolyte according to any one of claims 1 to 6, characterized in that it is as follows:
and mixing lithium salt, an organic solvent and ionic liquid to obtain the electrolyte.
8. The method according to claim 7, wherein the mixing temperature is 15 to 40 ℃.
9. The production method according to claim 7 or 8, wherein the mixing is performed in the presence of an inert gas;
preferably, the inert gas is selected from nitrogen and/or argon.
10. Use of an electrolyte according to any of claims 1 to 6 in a lithium sulphur battery or a lithium iron phosphate battery.
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