CN114824489A - Medium-salt-concentration electrolyte for lithium-sulfur battery - Google Patents
Medium-salt-concentration electrolyte for lithium-sulfur battery Download PDFInfo
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 46
- JDZCKJOXGCMJGS-UHFFFAOYSA-N [Li].[S] Chemical compound [Li].[S] JDZCKJOXGCMJGS-UHFFFAOYSA-N 0.000 title claims abstract description 13
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims abstract description 62
- 239000002904 solvent Substances 0.000 claims abstract description 51
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 39
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 27
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 27
- 150000002170 ethers Chemical class 0.000 claims abstract description 26
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000002161 passivation Methods 0.000 claims abstract description 9
- 150000003839 salts Chemical class 0.000 claims abstract description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 6
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 6
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 6
- 239000001301 oxygen Substances 0.000 claims abstract description 6
- 125000004430 oxygen atom Chemical group O* 0.000 claims abstract description 6
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 3
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 18
- 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 claims description 9
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 9
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 claims description 8
- ZAFNJMIOTHYJRJ-UHFFFAOYSA-N Diisopropyl ether Chemical compound CC(C)OC(C)C ZAFNJMIOTHYJRJ-UHFFFAOYSA-N 0.000 claims description 7
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 6
- SZNYYWIUQFZLLT-UHFFFAOYSA-N 2-methyl-1-(2-methylpropoxy)propane Chemical compound CC(C)COCC(C)C SZNYYWIUQFZLLT-UHFFFAOYSA-N 0.000 claims description 4
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 claims description 4
- ZUHZGEOKBKGPSW-UHFFFAOYSA-N tetraglyme Chemical compound COCCOCCOCCOCCOC ZUHZGEOKBKGPSW-UHFFFAOYSA-N 0.000 claims description 4
- DURPTKYDGMDSBL-UHFFFAOYSA-N 1-butoxybutane Chemical compound CCCCOCCCC DURPTKYDGMDSBL-UHFFFAOYSA-N 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- CWIFAKBLLXGZIC-UHFFFAOYSA-N 1,1,2,2-tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane Chemical compound FC(F)C(F)(F)OCC(F)(F)F CWIFAKBLLXGZIC-UHFFFAOYSA-N 0.000 claims description 2
- RQUBQBFVDOLUKC-UHFFFAOYSA-N 1-ethoxy-2-methylpropane Chemical compound CCOCC(C)C RQUBQBFVDOLUKC-UHFFFAOYSA-N 0.000 claims description 2
- PZHIWRCQKBBTOW-UHFFFAOYSA-N 1-ethoxybutane Chemical compound CCCCOCC PZHIWRCQKBBTOW-UHFFFAOYSA-N 0.000 claims description 2
- AOPDRZXCEAKHHW-UHFFFAOYSA-N 1-pentoxypentane Chemical compound CCCCCOCCCCC AOPDRZXCEAKHHW-UHFFFAOYSA-N 0.000 claims description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 2
- AQZGPSLYZOOYQP-UHFFFAOYSA-N Diisoamyl ether Chemical compound CC(C)CCOCCC(C)C AQZGPSLYZOOYQP-UHFFFAOYSA-N 0.000 claims description 2
- DHXVGJBLRPWPCS-UHFFFAOYSA-N Tetrahydropyran Chemical compound C1CCOCC1 DHXVGJBLRPWPCS-UHFFFAOYSA-N 0.000 claims description 2
- QQQCWVDPMPFUGF-ZDUSSCGKSA-N alpinetin Chemical compound C1([C@H]2OC=3C=C(O)C=C(C=3C(=O)C2)OC)=CC=CC=C1 QQQCWVDPMPFUGF-ZDUSSCGKSA-N 0.000 claims description 2
- SBZXBUIDTXKZTM-UHFFFAOYSA-N diglyme Chemical compound COCCOCCOC SBZXBUIDTXKZTM-UHFFFAOYSA-N 0.000 claims description 2
- KGPPDNUWZNWPSI-UHFFFAOYSA-N flurotyl Chemical compound FC(F)(F)COCC(F)(F)F KGPPDNUWZNWPSI-UHFFFAOYSA-N 0.000 claims description 2
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 claims description 2
- 229910001486 lithium perchlorate Inorganic materials 0.000 claims description 2
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 2
- YFNKIDBQEZZDLK-UHFFFAOYSA-N triglyme Chemical compound COCCOCCOCCOC YFNKIDBQEZZDLK-UHFFFAOYSA-N 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims 1
- 230000008021 deposition Effects 0.000 abstract description 9
- 230000000694 effects Effects 0.000 abstract description 5
- 229910052751 metal Inorganic materials 0.000 abstract description 3
- 239000002184 metal Substances 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 14
- 239000005077 polysulfide Substances 0.000 description 7
- 229920001021 polysulfide Polymers 0.000 description 7
- 150000008117 polysulfides Polymers 0.000 description 7
- 238000004090 dissolution Methods 0.000 description 6
- HCBRSIIGBBDDCD-UHFFFAOYSA-N 1,1,2,2-tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane Chemical group FC(F)C(F)(F)COC(F)(F)C(F)F HCBRSIIGBBDDCD-UHFFFAOYSA-N 0.000 description 5
- 239000012046 mixed solvent Substances 0.000 description 4
- 229920001774 Perfluoroether Polymers 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 239000003085 diluting agent Substances 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- SMBQBQBNOXIFSF-UHFFFAOYSA-N dilithium Chemical compound [Li][Li] SMBQBQBNOXIFSF-UHFFFAOYSA-N 0.000 description 2
- 238000010494 dissociation reaction Methods 0.000 description 2
- 230000005593 dissociations Effects 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- IRKHBNAABNTMHI-UHFFFAOYSA-N 1,2-dimethoxyethane;1,3-dioxolane Chemical compound C1COCO1.COCCOC IRKHBNAABNTMHI-UHFFFAOYSA-N 0.000 description 1
- YTWGSXKSYJOIOY-UHFFFAOYSA-N 1,3-dioxolane;methoxymethane Chemical compound COC.C1COCO1 YTWGSXKSYJOIOY-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- OPHUWKNKFYBPDR-UHFFFAOYSA-N copper lithium Chemical compound [Li].[Cu] OPHUWKNKFYBPDR-UHFFFAOYSA-N 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000005562 fading Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 239000012442 inert solvent Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- PYLWMHQQBFSUBP-UHFFFAOYSA-N monofluorobenzene Chemical compound FC1=CC=CC=C1 PYLWMHQQBFSUBP-UHFFFAOYSA-N 0.000 description 1
- 229910021392 nanocarbon Inorganic materials 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0569—Liquid materials characterised by the solvents
-
- 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
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
- H01M2300/0028—Organic electrolyte characterised by the solvent
- H01M2300/0037—Mixture of solvents
- H01M2300/0042—Four or more solvents
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses a medium-salt-concentration electrolyte for a lithium-sulfur battery, which contains a diether-fluorinated ether three-solvent system formed by mixed lithium salt, a first ether solvent, a second ether solvent and at least one fluorinated ether solvent; the mixed lithium salt contains a lithium salt capable of forming a passivation film on a lithium metal negative electrode; the first ether solvent has small oxygen coordination steric hindrance (the number of carbon atoms/the number of oxygen atoms in a molecule is less than or equal to 4) and can dissociate lithium salt; the second ether solvent has larger oxygen coordination steric hindrance (the number of carbon atoms/the number of oxygen atoms in a molecule is more than or equal to 5), and can reduce the salt concentration and the viscosity of the electrolyte; the fluorinated ether solvent can further reduce the concentration of lithium salt and improve the miscibility of electrolyte, and the fluorinated group of the fluorinated ether solvent can promote the formation of a stable lithium metal negative electrode passivation layer and improve the deposition stripping efficiency of negative electrode metal. The electrolyte provided by the invention can be used for assembling lithium batteries, and the assembled lithium batteries have the advantages of long cycle life, weak self-discharge effect, high conductivity, low viscosity, good wettability and higher commercial application value.
Description
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to a medium-salt-concentration electrolyte for a lithium-sulfur battery.
Background
Since lithium metal has a very high theoretical specific capacity, a lithium metal battery using lithium metal as a negative electrode has a great potential as a next-generation secondary battery because of its outstanding theoretical energy density. During charging and discharging, the electrolyte may continuously undergo side reactions with metallic lithium and be accompanied by lithium dendrite growth, thereby causing capacity fade or short circuit of the battery. The NCM positive electrode material and the sulfur-containing material also cause severe self-discharge and capacity fade of the battery with dissolution of components. The elemental sulfur has rich reserve capacity, low price and very high theoretical specific capacity (1670 mAh/g). However, the conventional lithium-sulfur battery is faced with the problem of the loss of active material due to the shuttling effect of lithium polysulfide, which is an intermediate product in discharge; and these problems severely limit the commercial large-scale application of lithium sulfur batteries.
In view of the above problems, researchers have proposed a series of different solutions, such as using transition metal ion-doped nanocarbon having an adsorption capacity to lithium polysulfide as a support and coating structure of a positive electrode material, or using a surface-modified separator, and using an ether electrolyte containing a lithium nitrate additive having a passivation effect on a negative electrode metal surface. The traditional ester electrolyte can not effectively passivate the surface of a lithium metal cathode, so that the stripping and deposition efficiency of lithium is low, and the cycle life of the battery is short. In addition, the prior art scheme represented by a glycol dimethyl ether-1, 3-dioxolane mixed solvent system still causes a lithium polysulfide shuttling effect, the deposition and stripping efficiency of lithium is generally lower than 99%, and the cycle life of the battery is short. Although the locally difficult electrolyte based on fluoroether as a single diluent reported previously can inhibit the dissolution of the positive active material, the fluoroether solvent has strong volatility and high cost, and cannot promote the dissolution of lithium salt, so that the electrolyte cannot meet the commercialization requirements. In addition, fluorobenzene and its homologues are a low cost alternative to potential fluoroether solvents, but the solvents have low fluorine content and high toxicity. Therefore, the corresponding electrolyte cannot form an excellent passivation layer on the surface of the lithium metal and has great harm to the environment. In addition, since the dissociation of lithium ions is greatly restricted, an electrolyte using a single low-viscosity inert solvent (e.g., n-butyl ether) exhibits very low lithium ion conductivity.
Disclosure of Invention
In view of the above technical problems, the present invention provides a medium salt electrolyte for a lithium-sulfur battery to solve the problems of rapid capacity fading, severe self-discharge during storage, and severe side reactions between a lithium negative electrode and the electrolyte in a low-rate cycle condition of a lithium metal battery in the prior art. The lithium metal battery electrolyte provided by the invention contains a mixed lithium salt and a ternary mixed solvent consisting of diether-fluorinated ether, can be used for assembling a lithium metal battery, the assembled lithium battery can simultaneously meet the practical requirements of long cycle life, weak self-discharge effect and the like, and the electrolyte has high enough conductivity, low viscosity and excellent wettability, thereby having high commercial value.
The technical scheme provided by the invention is as follows:
a medium salt electrolyte for a lithium sulfur battery: the double-ether-fluorinated ether three-solvent system is formed by mixed lithium salt, a first ether solvent, a second ether solvent and at least one fluorinated ether solvent;
wherein the content of the first and second substances,
the mixed lithium salt contains a lithium salt capable of forming a passivation film on a lithium metal negative electrode;
the oxygen coordination steric hindrance of the first ether solvent is small, the number of carbon atoms/oxygen atoms in a molecule is less than or equal to 4, and lithium salt can be dissociated;
the second ether solvent has larger oxygen coordination steric hindrance, and the number of carbon atoms/oxygen atoms in molecules is more than or equal to 5, so that the salt concentration and the viscosity of the electrolyte can be reduced;
the fluorinated ether solvent can further reduce the concentration of lithium salt and improve the miscibility of the electrolyte, and the fluorinated group of the fluorinated ether solvent can promote the formation of a stable lithium metal negative electrode passivation layer.
Further, the first ether solvent is selected from one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and tetrahydrofuran. Preferably, the first ether solvent is tetrahydrofuran.
Further, the second ether solvent is one selected from tetrahydropyran, n-propyl ether, isopropyl ether, ethyl butyl ether, ethyl isobutyl ether, n-butyl ether, isobutyl ether, n-pentyl ether and isoamyl ether. Preferably, the second ether solvent is isopropyl ether.
Further, the fluorinated ether solvent is one or more selected from the group consisting of 1- (2,2, 2-trifluoroethoxy) -1,1,2, 2-tetrafluoroethane, 1,2, 2-tetrafluoroethyl 2,2,3, 3-tetrafluoropropyl ether, and bis (2,2, 2-trifluoroethyl) ether. Preferably, the fluorinated ether solvent is 1,1,2, 2-tetrafluoroethyl 2,2,3, 3-tetrafluoropropyl ether isopropyl ether.
Furthermore, the first ether solvent is tetrahydrofuran, the fluorinated ether solvent is 1,1,2, 2-tetrafluoroethyl 2,2,3, 3-tetrafluoropropyl ether isopropyl ether, and the molar ratio of the two is 1 (0.1-3). The preferred molar ratio is 8: 9.
Further, the mixed lithium salt is selected from two or more of lithium hexafluorophosphate, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide, lithium tetrafluoroborate, lithium bis (fluorooxalato) borate, lithium hexafluoroarsenate or lithium perchlorate.
Furthermore, the mixed lithium salt is a mixture of lithium bis (trifluoromethylsulfonyl) imide and lithium bis (fluorosulfonyl) imide, and the molar ratio is 1 (0.1-3). The preferred molar ratio is 1: 3.
further, the molar ratio of the first ether solvent to the second ether solvent is (0.1-10): 1.
Further, the molar ratio of the first ether solvent to the fluorinated ether solvent is 1 (0.1 to 3).
Further, the total concentration of the mixed lithium salt is 1.0 mol/L-2.0 mol/L. The preferable concentration is 1.5-2.0 mol/L.
The invention has the following beneficial effects:
(1) the ternary mixed solvent composed of the diether-fluorinated ether solvent is used as a diluent for the electrolyte of the lithium-sulfur battery, and the weak polar ether solvent (first ether solvent and second ether solvent) with chemical inertness effectively reduces the use proportion of the fluorinated ether so as to reduce the cost, improve the dissociation capability of lithium salt and reduce the salt concentration and the viscosity of the electrolyte; the use of the fluorinated ether is beneficial to the electrolyte to form a stable passivation layer on the lithium metal negative electrode, the deposition stripping efficiency of the negative electrode metal is improved, and the side reaction can be effectively inhibited. In addition, the introduction of the fluorinated ether improves the miscibility of the weak polar ether solvent and expands the working temperature range of the electrolyte.
(2) The concentration of the mixed lithium salt in the electrolyte is 2.0-1.0 mol/L, and the electrolyte in the salt concentration range has lower viscosity and synergistically inhibits the dissolution of the active material of the positive electrode on the premise of ensuring that the lithium negative electrode has higher deposition stripping efficiency.
Drawings
Fig. 1 is a lithium-lithium symmetric cycling test of solution assembly of various embodiments.
FIG. 2 is a lithium polysulfide solubility test of solutions of various examples.
FIG. 3 is a test of stripping efficiency for lithium deposition incorporating various ratios of fluorinated ether solutions.
Fig. 4 is a capacity retention rate test after a long-time shelf of the solution-assembled battery of the control group 1.
Fig. 5 is a capacity retention rate test after a long-term shelf life of the solution assembled battery of example 2.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the embodiments and the accompanying drawings. The specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they are in conflict with each other.
Example 1
Preparing a solution from lithium bis (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide, tetrahydrofuran, isopropyl ether and 1,1,2, 2-tetrafluoroethyl 2,2,3, 3-tetrafluoropropyl ether according to the mass ratio of 1:3:8:2: 5.
Example 2
Preparing a solution from lithium bis (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide, tetrahydrofuran, isopropyl ether and 1,1,2, 2-tetrafluoroethyl 2,2,3, 3-tetrafluoropropyl ether according to the mass ratio of 1:3:8:2: 9.
Example 3
Preparing a solution from lithium bis (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide, tetrahydrofuran, isopropyl ether and 1,1,2, 2-tetrafluoroethyl 2,2,3, 3-tetrafluoropropyl ether according to the mass ratio of 1:3:8:2: 18.
Control group 1
Preparing a control electrolyte, and dissolving lithium bis (trifluoromethylsulfonyl) imide in a volume ratio of 1: in the mixed solvent of 1 ethylene glycol dimethyl ether-1, 3-dioxolane, the concentration of lithium salt is 1mol/L, and the electrolyte is the most widely used electrolyte in the current lithium-sulfur battery.
Control group 2
Preparing a solution from lithium bis (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide, tetrahydrofuran and isopropyl ether according to the mass ratio of 1:3:8: 2.
The performance test results of the electrolyte prepared in the examples are as follows:
the electrolyte of control 2, example 1, example 2 and example 3 was used together with a lithium sheet, a separator and a steel mesh to assemble a lithium-lithium symmetrical battery at 1mA cm -2 Long cycle test (1 h for each charge and discharge) was performed at the current density of (g). As shown in fig. 1, the control group 2, example 1, and example 2 all achieved a long stabilization cycle, and example 1 and example 2 maintained a relatively low polarization voltage, while example 3 exhibited a large polarization voltage due to a low lithium salt concentration, and a short circuit occurred as the cycle time was extended.
Lithium polysulfide was added to the solutions corresponding to control 1, control 2, example 1, example 2, and example 3, and the mixture was stirred for 30 minutes to form a saturated solution, and the solution was allowed to stand for 1 week and then observed for color. As shown in fig. 2, control 1 appeared opaque dark brown, indicating that significant dissolution of lithium polysulfide occurred, and examples 1,2, and 3 showed lighter color than control 2, indicating that the use of mixed diluents can further inhibit dissolution of lithium polysulfide.
The solutions described in control 2, example 1, example 2 and example 3 were used to assemble lithium copper half-cells with lithium sheets, copper sheets and separators at 0.5mA cm -2 Current density of 1mAh cm -2 The deposition stripping coulombic efficiency test was performed at the face volume density of (1). As shown in fig. 3, when the molar ratio of tetrahydrofuran to fluorinated ether is 8:0 and 8:9 for the control group 2 and the example group 2, the deposition stripping efficiency corresponding to lithium is 99.3% and 99.6%, respectively, and both can be stably cycled for not less than 300 times, which shows that the deposition stripping efficiency of lithium can be obviously improved by introducing the fluorinated ether in a proper ratio.
The solutions of the control group 1 and the example 2, lithium foil, a diaphragm and a sulfur positive pole piece are assembled together to form a button simulation lithium-sulfur battery, and the button simulation lithium-sulfur battery is subjected to charge-discharge cycles for a plurality of times in a voltage range of 1.0V-3.0V, then discharged to 1.9V, and continuously cycled after being placed for 10 days. As shown in fig. 4, the battery using the electrolyte of the control group exhibited a significant self-discharge phenomenon after being left alone. As shown in fig. 5, the batteries using the experimental electrolyte set according to the present invention did not show capacity fade due to self-discharge after being left.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A medium salt electrolyte for a lithium sulfur battery, comprising: the electrolyte contains a double-ether-fluorinated ether three-solvent system formed by mixed lithium salt, a first ether solvent, a second ether solvent and at least one fluorinated ether solvent;
wherein the content of the first and second substances,
the mixed lithium salt contains a lithium salt capable of forming a passivation film on a lithium metal negative electrode;
the first ether solvent has small oxygen coordination steric hindrance, has a carbon atom number/oxygen atom number less than or equal to 4 in a molecule, and can dissociate lithium salt;
the second ether solvent has larger oxygen coordination steric hindrance, and the number of carbon atoms/oxygen atoms in molecules is more than or equal to 5, so that the salt concentration and the viscosity of the electrolyte can be reduced;
the fluorinated ether solvent can further reduce the concentration of lithium salt and improve the miscibility of the electrolyte, and the fluorinated group of the fluorinated ether solvent can promote the formation of a stable lithium metal negative electrode passivation layer.
2. The electrolyte of claim 1, wherein: the first ether solvent is selected from one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and tetrahydrofuran.
3. The electrolyte of claim 1, wherein: the second ether solvent is selected from one of tetrahydropyran, n-propyl ether, isopropyl ether, ethyl butyl ether, ethyl isobutyl ether, n-butyl ether, isobutyl ether, n-pentyl ether and isoamyl ether.
4. The electrolyte of claim 1, wherein: the fluorinated ether solvent is selected from one or more of 1- (2,2, 2-trifluoroethoxy) -1,1,2, 2-tetrafluoroethane, 1,2, 2-tetrafluoroethyl 2,2,3, 3-tetrafluoropropyl ether and bis (2,2, 2-trifluoroethyl) ether.
5. The electrolyte of claim 1, wherein: the mixed lithium salt is selected from two or more of lithium hexafluorophosphate, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide, lithium tetrafluoroborate, lithium bis (fluorooxalato) borate, lithium hexafluoroarsenate or lithium perchlorate.
6. The electrolyte of claim 5, wherein: the mixed lithium salt is a mixture of lithium bis (trifluoromethylsulfonyl) imide and lithium bis (fluorosulfonyl) imide, and the molar ratio is 1 (0.1-3).
7. The electrolyte of claim 1, wherein: the molar ratio of the first ether solvent to the second ether solvent is (0.1-10): 1.
8. The electrolyte of claim 1, wherein: the molar ratio of the first ether solvent to the fluorinated ether solvent is 1 (0.1-3).
9. The electrolyte of claim 1, wherein: the total concentration of the mixed lithium salt is 1.0 mol/L-2.0 mol/L.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005108724A (en) * | 2003-09-30 | 2005-04-21 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
| KR20170084452A (en) * | 2016-01-12 | 2017-07-20 | 주식회사 엘지화학 | Non-aqueous liquid electrolye for lithium-sulfur battery and lithium-sulfur battery comprising the same |
| KR20210115319A (en) * | 2020-03-12 | 2021-09-27 | 주식회사 엘지화학 | Electrolyte for lithium-sulfur secondary battery and lithium-sulfur secondary battery comprising the same |
| CN113948771A (en) * | 2021-10-14 | 2022-01-18 | 安徽工业大学 | Safe low-concentration electrolyte for lithium battery and application thereof |
| CN114204119A (en) * | 2021-11-29 | 2022-03-18 | 南京医电应用科技研究院有限公司 | Lithium-sulfur battery electrolyte containing mixed lithium salt of low-polarity ethers |
-
2022
- 2022-05-20 CN CN202210555628.2A patent/CN114824489A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005108724A (en) * | 2003-09-30 | 2005-04-21 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
| KR20170084452A (en) * | 2016-01-12 | 2017-07-20 | 주식회사 엘지화학 | Non-aqueous liquid electrolye for lithium-sulfur battery and lithium-sulfur battery comprising the same |
| KR20210115319A (en) * | 2020-03-12 | 2021-09-27 | 주식회사 엘지화학 | Electrolyte for lithium-sulfur secondary battery and lithium-sulfur secondary battery comprising the same |
| CN113948771A (en) * | 2021-10-14 | 2022-01-18 | 安徽工业大学 | Safe low-concentration electrolyte for lithium battery and application thereof |
| CN114204119A (en) * | 2021-11-29 | 2022-03-18 | 南京医电应用科技研究院有限公司 | Lithium-sulfur battery electrolyte containing mixed lithium salt of low-polarity ethers |
Non-Patent Citations (1)
| Title |
|---|
| KE SUN ET AL.: "Electrolyte with Low Polysulfide Solubility for Li-S Batteries", 《ACS APPLIEDENERGY MATERIALS》, vol. 1, no. 1, 23 May 2018 (2018-05-23), pages 2608 - 2618 * |
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