CN110911756B - Diluted lithium salt mixed lithium-sulfur battery electrolyte - Google Patents
Diluted lithium salt mixed lithium-sulfur battery electrolyte Download PDFInfo
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Abstract
本发明涉及一种稀释的混合锂盐的锂硫电池电解液，属于锂硫电池技术领域。该电解液含有混合锂盐、溶解混合锂盐的溶剂和稀释剂，溶剂混合锂盐的溶剂优选地为酯类或醚类溶剂，稀释剂优选地为氟代醚类化合物或芳香类化合物。本这种电解液能够用于高性能锂硫电池，同时起到稳定锂负极和促进硫正极容量发挥的作用。该电解液通过加入不同的锂盐按一定比例混合达到兼顾锂负极保护和硫正极容量发挥的双重功效，并且由于稀释剂的加入使得该电解液具有高的电导率，低的粘度，良好的浸润性，大大降低了电解液的成本，能够大规模应用，具有极高的商业价值。
The invention relates to a dilute mixed lithium salt lithium-sulfur battery electrolyte, which belongs to the technical field of lithium-sulfur batteries. The electrolyte contains a mixed lithium salt, a solvent for dissolving the mixed lithium salt, and a diluent. The solvent for the mixed lithium salt is preferably an ester or ether solvent, and the diluent is preferably a fluorinated ether compound or an aromatic compound. This electrolyte can be used in high-performance lithium-sulfur batteries, and at the same time plays the role of stabilizing the lithium negative electrode and promoting the capacity of the sulfur positive electrode. The electrolyte is mixed in a certain proportion by adding different lithium salts to achieve the dual effect of taking into account the protection of lithium negative electrode and the capacity of sulfur positive electrode, and due to the addition of diluent, the electrolyte has high conductivity, low viscosity, good infiltration It can greatly reduce the cost of electrolyte, can be applied on a large scale, and has extremely high commercial value.
Description
Technical Field
The invention belongs to the technical field of lithium-sulfur batteries, and particularly relates to a diluted lithium salt mixed lithium-sulfur battery electrolyte.
Background
The lithium-sulfur battery is regarded as a next-generation secondary battery with great prospect due to the characteristics of high theoretical specific capacity (1670mAh/g) and wide material resources and low cost. However, current lithium sulfur batteries face the shuttling effect of the sulfur positive electrode, low capacity exertion at high loading, and problems of dendritic growth of the lithium negative electrode. These problems greatly affect the practical application and large-scale commercialization prospects of lithium-sulfur batteries.
For the above problems, although there are a series of studies to propose respective solutions, for example, zhangguang et al in north western countries of pacific usa uses a local high concentration electrolyte to improve a solvation structure in the electrolyte to accelerate lithium ion transport, and to uniformize lithium metal deposition to suppress dendritic growth on the surface of the lithium metal (Adv Mater 201830 (21): e 1706102). The method is characterized in that a film-forming additive is added into an electrolyte to form a special protective layer on the surface of sulfur, so that the dissolution of polysulfide ions is inhibited, and the shuttle effect is reduced (Journal of Materials Chemistry A20186 (46): 23396-.
Disclosure of Invention
The invention solves the problems that the polarization large capacity of a high-capacity anode in a lithium sulfur battery can not be normally exerted and the service life of a lithium cathode is rapidly reduced in the prior art. The electrolyte of the lithium-sulfur battery contains the mixed lithium salt, can be used for the lithium-sulfur battery under the actual test condition, namely, the harsh conditions of high loading capacity, low electrolyte, limited lithium source and the like are met, and the electrolyte has high conductivity, low viscosity and good wettability, greatly reduces the cost of the electrolyte, can be applied in a large scale and has extremely high commercial value.
In accordance with the object of the present invention, there is provided a diluted lithium mixed lithium salt lithium sulfur battery electrolyte comprising a mixed lithium salt, a solvent dissolving the mixed lithium salt, and a diluent; the mixed lithium salt contains at least one lithium salt mainly capable of forming a film on a lithium negative electrode of the lithium-sulfur battery and at least one lithium salt mainly capable of forming a film on a sulfur positive electrode of the lithium-sulfur battery; the lithium salt mainly capable of forming a film on a lithium cathode of the lithium-sulfur battery is used for improving the conductivity of the electrolyte, and the lithium salt mainly capable of forming a film on a sulfur anode of the lithium-sulfur battery is used for preventing the corrosion of a current collector of the lithium-sulfur battery; the mixed lithium salt is used for improving the lithium ion transmission performance of the electrolyte to the sulfur anode of the lithium-sulfur battery and improving the oxidation resistance of the electrolyte, thereby promoting the capacity exertion and the circulation stability of the sulfur anode and improving the potential window of the electrolyte.
Preferably, the lithium salt mainly capable of forming a film on the lithium negative electrode of the lithium-sulfur battery is lithium bis (fluorosulfonyl) imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate or lithium perchlorate; the lithium salt mainly capable of forming a film on the sulfur positive electrode of the lithium-sulfur battery is lithium bistrifluoromethylsulfonyl imide, lithium difluorooxalato borate, lithium difluorophosphate or lithium dioxaoxalato borate;
preferably, the lithium salt mainly capable of forming a film on a lithium negative electrode of the lithium-sulfur battery is lithium bis (fluorosulfonyl) imide, and the lithium salt mainly capable of forming a film on a sulfur positive electrode of the lithium-sulfur battery is lithium bis (trifluoromethanesulfonyl) imide.
Preferably, the concentration of the mixed lithium salt in the electrolyte is 1 mol/L-10 mol/L.
Preferably, the amount of the lithium salt which can be mainly formed on the lithium negative electrode of the lithium-sulfur battery and the lithium salt which can be mainly formed on the sulfur positive electrode of the lithium-sulfur battery is (1-10): 1.
Preferably, the solvent for dissolving the lithium salt is at least one of an ester solvent and an ether solvent.
Preferably, the ester solvent is ethylene carbonate, dimethyl carbonate, diethyl carbonate, fluoro carbonate or propylene carbonate, and the ether solvent is ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran or 1, 3-dioxolane.
Preferably, the ratio of the amount of the solvent for dissolving the lithium mixture to the amount of the substance for dissolving the lithium mixture is (1-20): 1.
Preferably, the diluent is at least one of a fluoroether compound and an aromatic compound.
Preferably, the fluoroether compound is at least one of 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether, 2,2, 2-trifluoroethyl ether and hexafluoroisopropyl methyl ether, and the aromatic compound is at least one of benzene, halogenated benzene homolog, halogenated benzene isomer, alkane benzene homolog and alkane benzene isomer;
preferably, the halogenated benzene is fluorobenzene, methylfluorobenzene, chlorobenzene, bromobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene or hexafluorobenzene; the halogenated benzene isomer is difluorobenzene isomer, trifluorobenzene isomer, tetrafluorobenzene isomer or methyl fluorobenzene isomer; the alkane benzene is toluene or ethylbenzene.
Preferably, the amount ratio of the diluent to the lithium salt mixture is (1-10): 1.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
(1) the electrolyte contains a mixed lithium salt, a solvent for dissolving the mixed lithium salt and a diluent; the mixed lithium salt contains at least one lithium salt which can mainly form a film on a lithium cathode of the lithium-sulfur battery, and a small amount of the lithium salt forms a film on a sulfur anode; and at least one lithium salt capable of forming a film mainly on the positive electrode of sulfur in the lithium-sulfur battery, and a small amount of lithium salt capable of forming a film on the negative electrode of lithium; the lithium salt mainly capable of forming a film on a lithium cathode of the lithium-sulfur battery is used for improving the conductivity of the electrolyte, and the lithium salt mainly capable of forming a film on a sulfur anode of the lithium-sulfur battery is used for preventing the corrosion of a current collector of the lithium-sulfur battery; the mixed lithium salt is used for improving the lithium ion transmission performance of the electrolyte to the sulfur anode of the lithium-sulfur battery and improving the oxidation resistance of the electrolyte, thereby promoting the capacity exertion and the circulation stability of the sulfur anode and improving the potential window of the electrolyte.
(2) At present, most methods can only be independently applied to a positive electrode or a negative electrode and cannot give consideration to both the positive electrode and the negative electrode, so that the service life of the lithium-sulfur full battery cannot be really prolonged, and particularly under severe test conditions including high loading capacity, low electrolyte and limited lithium sources, the actual cycle performance is difficult to guarantee. The present invention thus provides a dilute lithium salt mixed lithium-sulfur battery electrolyte. The electrolyte can simultaneously act on a positive electrode and a negative electrode by adding mixed lithium salt, has high conductivity, low viscosity and good wettability by adding a diluent, can effectively and greatly prolong the cycle life of a lithium-sulfur battery, is particularly applied to a lithium-sulfur secondary battery under actual conditions, greatly reduces the cost of the electrolyte, can be applied in a large scale and has high commercial value.
(3) The mixed lithium salt in the electrolyte is preferably the mixed lithium salt of the bis-fluoro-sulfonyl-imide lithium and the bis-trifluoromethyl-sulfonyl-imide lithium, and the addition of the bis-trifluoromethyl-sulfonyl-imide lithium greatly improves the lithium ion transmission performance of the electrolyte to the sulfur anode and improves the oxidation resistance of the electrolyte, thereby promoting the capacity exertion and the circulation stability of the sulfur anode, and improving the potential window of the electrolyte so that the electrolyte can be matched with more anode materials. The single lithium bis (fluorosulfonate) imide can severely corrode a current collector under a high-pressure condition, and the decomposition of the current collector can be obviously inhibited when a certain amount of lithium bis (trifluoromethanesulfonyl) imide is added, so that the cycle life of the battery is obviously prolonged.
(4) The preferable diluent is 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether, the addition of the diluent can change the solvation effect of the electrolyte, stable free solvent molecules are added to accelerate lithium ion transmission, the degree of local current density unevenness on the surface of the lithium metal is reduced, the coulombic efficiency of the lithium metal battery can be effectively improved, and the cycle life of the lithium metal battery is greatly prolonged.
(5) According to the invention, the concentration of the mixed lithium salt in the electrolyte is preferably 1-10 mol/L, so that the electrolyte with the lithium salt concentration has low viscosity, smaller density and lower cost, and can also protect a lithium cathode to have higher coulombic efficiency, thereby prolonging the cycle life of the lithium-sulfur battery.
(6) According to the invention, the mixed lithium salt is preferably a mixture of two different lithium salts, the amount of substances of the two different lithium salts is (1-10): 1, and the electrolyte prepared according to the proportion has the conductivity exceeding that of a single lithium salt electrolyte and has a high lithium ion diffusion coefficient, so that the capacity of the lithium-sulfur battery can be greatly exerted, the sulfur utilization rate is greatly improved, and the polarization can be effectively reduced, thereby further prolonging the cycle life.
Drawings
Fig. 1 is a coulombic efficiency test of example 1 on a lithium negative electrode using an electrolyte of a diluted mixed lithium salt proposed in the present invention.
Fig. 2 is a coulombic efficiency test of example 3 using electrolytes of mixed lithium salts of different ratios proposed in the present invention on a lithium negative electrode.
Fig. 3 is a deposition profile of an electrolyte of example 5 using a diluted mixed lithium salt proposed by the present invention.
Fig. 4 is a conductivity test of the electrolyte of example 7 using mixed lithium salts of different compounding ratios proposed in the present invention.
Fig. 5 is a capacity exertion test of example 9 using an electrolyte of a diluted mixed lithium salt proposed by the present invention for a sulfur positive electrode.
Fig. 6 is a graph of the cycle capacity of a lithium-sulfur full cell assembled in example 11 using a dilute lithium salt mixed electrolyte as proposed by the present invention.
Fig. 7 is a schematic diagram of a lithium-sulfur pouch cell assembled in example 13 using a dilute lithium salt mixed electrolyte as proposed by the present invention.
Fig. 8 is a graph of the cycle capacity of a lithium-sulfur pouch cell assembled in example 14 using a dilute lithium salt mixed electrolyte as proposed by the present invention.
Fig. 9 is a lithium ion transport performance test of example 15 using an electrolyte of a diluted mixed lithium salt proposed by the present invention for a sulfur positive electrode.
Fig. 10 example 16 linear sweep voltammetry tests using the electrolyte of diluted mixed lithium salts proposed by the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. 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 do not conflict with each other.
A diluted lithium mixed lithium salt lithium-sulfur battery electrolyte comprises a mixed lithium salt, a solvent for dissolving the mixed lithium salt and a diluent; the mixed lithium salt contains at least one lithium salt mainly capable of forming a film on a lithium negative electrode of the lithium-sulfur battery and at least one lithium salt mainly capable of forming a film on a sulfur positive electrode of the lithium-sulfur battery; the lithium salt mainly capable of forming a film on a lithium cathode of the lithium-sulfur battery is used for improving the conductivity of the electrolyte, and the lithium salt mainly capable of forming a film on a sulfur anode of the lithium-sulfur battery is used for preventing the corrosion of a current collector of the lithium-sulfur battery; the mixed lithium salt is used for improving the lithium ion transmission performance of the electrolyte to the sulfur anode of the lithium-sulfur battery and improving the oxidation resistance of the electrolyte, thereby promoting the capacity exertion and the circulation stability of the sulfur anode and improving the potential window of the electrolyte.
The concentration of the mixed lithium salt in the electrolyte is 1-10 mol/L, and more preferably 2 mol/L; the mixed lithium salt is a mixture of lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethylsulfonyl) imide, and the mass ratio of the lithium bis (fluorosulfonyl) imide to the lithium bis (trifluoromethylsulfonyl) imide is (1-10): 1, preferably (1-3): 1, and further preferably 2: 1; the ratio of the solvent for dissolving the lithium mixture to the substance for dissolving the lithium mixture is (1-20): 1, preferably (1-10): 1, and more preferably 2: 1; the amount ratio of the diluent to the substance mixed with the lithium salt is (1-10: 1), preferably 4: 1.
Example 1
Respectively preparing uniform solutions (a control group 1, a control group 2 and an experimental group in sequence) from lithium bifluoride sulfimide, lithium bistrifluoromethylsulfonyl imide, ethylene glycol dimethyl ether and 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether according to the molar ratio of 0:1:2:4,1:0:2:4 and 1:1:2:4, assembling the lithium copper half-cell together with a lithium sheet, a copper sheet and a diaphragm at the concentration of 1mA cm-2As shown in fig. 1, in the experimental group to which the electrolytes of lithium bis (fluorosulfonyl imide) and lithium bis (trifluoromethanesulfonyl imide) were added simultaneously, the lithium negative electrode stabilized over 600 cycles, and the average coulombic efficiency was higher than 99.4%, while the control group 1 failed to normally circulate, and the control group 2 was able to circulate but the coulombic efficiency was inferior to that of the experimental group.
Example 2
The solvent used was dimethyl carbonate, as in example 1.
Example 3
Respectively preparing uniform solutions (proportion 1, proportion 2 and proportion 3 in sequence) from lithium bifluoride sulfonyl imide, lithium bistrifluoromethyl sulfonyl imide, ethylene glycol dimethyl ether and 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether according to the molar ratio of 1:1:2:4,1:2:2:4 and 2:1:2:4, assembling the lithium copper half-cell together with a lithium sheet, a copper sheet and a diaphragm by using the electrolyte, and assembling the lithium copper half-cell at 1mA cm-2The coulomb efficiency test was performed at the current density of (1), as shown in FIG. 2The ratio 3, namely the ratio of the lithium bis (fluorosulfonyl) imide to the lithium bis (trifluorosulfonyl) imide is 2:1, the coulombic efficiency of the lithium negative electrode is highest.
Example 4
The ratio of lithium salt to ethylene glycol dimethyl ether used was 1: 3, the rest of the procedure was the same as in example 3.
Example 5
Preparing uniform solution from lithium difluoride sulfimide, lithium bistrifluoromethyl sulfimide, ethylene glycol dimethyl ether and 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether according to the molar ratio of 2:1:2:4, assembling a lithium-copper half-cell together with a lithium sheet, a copper sheet and a diaphragm by using the electrolyte, and depositing 5mAh cm-2The lithium is on the surface of the copper sheet, the copper sheet is taken out to shoot the appearance of the lithium deposition, and as shown in figure 3, the lithium deposited by the electrolyte has a uniform and compact surface.
Example 6
The diluent used was 2,2, 2-trifluoroethyl ether, as in example 5.
Example 7
Respectively preparing a uniform solution (proportion 1, proportion 2 and proportion 3 in sequence) from lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide and ethylene glycol dimethyl ether in a molar ratio of 1:1:2:4,1:2:2:4 and 2:1:2:4, and using the electrolyte, a stainless steel sheet and a diaphragm to assemble a battery, and measuring impedance at room temperature to compare conductivity of different electrolytes, wherein the proportion 3 is that the proportion of lithium bis (fluorosulfonyl) imide to lithium bis (trifluorosulfonyl) imide is 2:1, the highest conductivity.
Example 8
The ratio of the lithium salt to the diluent 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether used was 1:2, the rest of the same procedure as in example 7.
Example 9
Respectively preparing uniform solutions (a control group 1, a control group 2 and an experimental group in sequence) from lithium bifluoride sulfimide, lithium bistrifluoromethylsulfonyl imide, ethylene glycol dimethyl ether and 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether according to the molar ratio of 0:1:2:4,1:0:2:4 and 1:1:2:4, and using the electrolyte, a lithium sheet, a high-load sulfur positive electrode and a diaphragm to form a group togetherAnd packaging to obtain the lithium-sulfur full cell. At 0.5mA cm-2The current is charged and discharged, and the charging and discharging conditions of the first circle of different electrolytes are compared, so that the polarization of the first circle of different electrolytes is judged. As shown in fig. 5, the sulfur positive electrode for the experimental group had the highest capacity exertion and the lowest polarization voltage.
Example 10
The remaining examples were the same as example 9, except that the lithium mixed salt used was lithium hexafluorophosphate and lithium trifluoromethanesulfonylimide.
Example 11
Respectively preparing uniform solutions (a control group 1, a control group 2 and an experimental group in sequence) from lithium difluoride sulfimide, lithium bistrifluoromethylsulfonyl imide and ethylene glycol dimethyl ether in a molar ratio of 0:1:2:4,1:0:2:4 and 1:1:2:4, using the electrolyte, a lithium sheet, a high-capacity sulfur positive electrode and a diaphragm to assemble a lithium-sulfur full cell, and performing a circulation test under a current of 1mA cm-2, wherein the circulation stability exceeds 50 circles and the capacity exertion exceeds 10mAh cm-2 in the experimental group with diluted mixed salt electrolyte as shown in figure 6-2And is much better than the control groups 1 and 2.
Example 12
The lithium salt mixture used was lithium hexafluorophosphate and lithium tetrafluoroborate, as in example 11.
Example 13
Lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, ethylene glycol dimethyl ether, 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether are prepared into a uniform solution according to a molar ratio of 2:1:2:4, and the electrolyte, a lithium foil, a high-load sulfur positive electrode and a diaphragm are used for assembling the lithium-sulfur soft package battery together, as shown in fig. 7.
Example 14
Preparing uniform solution from lithium difluoride sulfimide, lithium bistrifluoromethyl sulfimide, ethylene glycol dimethyl ether and 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether according to the molar ratio of 2:1:2:4, assembling the lithium-sulfur soft package battery by using the electrolyte, a lithium foil, a high-load sulfur positive electrode and a diaphragm together, and performing high-temperature sintering at 0.5 mA/cm-2The current is charged and discharged, and the practical application value of the current is tested. As shown in FIG. 8, this dilution was usedThe soft package battery assembled by the mixed salt electrolyte can be stably circulated, and the coulomb efficiency is kept above 99.8%.
Example 15
Respectively preparing uniform solutions (a comparison group 1, a comparison group 2 and an experimental group in sequence) from difluoride sulfimide lithium, bistrifluoromethyl sulfimide lithium and ethylene glycol dimethyl ether in a molar ratio of 0:1:2:4,1:0:2:4 and 1:1:2:4, and 3-tetrafluoropropyl ether, assembling the electrolyte, a lithium sheet, a sulfur positive electrode and a diaphragm into a lithium-sulfur battery, measuring cyclic voltammetry curves of the battery at different sweep rates, and drawing a half power of peak current and a sweep rate, wherein the slope rate reflects the lithium ion transmission performance of the electrolyte to the sulfur positive electrode. As shown in fig. 9, it is the most excellent lithium ion transport performance for the sulfur positive electrode in the experimental group with the diluted mixed salt electrolyte.
Example 16
Respectively preparing uniform solutions (a control group 1, a control group 2 and an experimental group in sequence) from lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethanesulfonyl) imide, ethylene glycol dimethyl ether and 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether according to the molar ratio of 0:1:2:4,1:0:2:4 and 1:1:2:4, assembling a lithium-stainless steel battery together with the electrolyte, a lithium sheet, stainless steel and a diaphragm, and measuring a linear scanning voltammetry curve of the battery to judge a potential window of the battery. As shown in fig. 10, the potential window was the widest in the experimental group with diluted mixed salt electrolyte, i.e. it remained stable at a voltage of 5V.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (11)
1. A diluted lithium mixed lithium salt lithium-sulfur battery electrolyte is characterized by comprising a mixed lithium salt, a solvent for dissolving the mixed lithium salt and a diluent; the mixed lithium salt contains at least one lithium salt mainly capable of forming a film on a lithium negative electrode of the lithium-sulfur battery and at least one lithium salt mainly capable of forming a film on a sulfur positive electrode of the lithium-sulfur battery; the lithium salt mainly capable of forming a film on a lithium cathode of the lithium-sulfur battery is used for improving the conductivity of the electrolyte, and the lithium salt mainly capable of forming a film on a sulfur anode of the lithium-sulfur battery is used for preventing the corrosion of a current collector of the lithium-sulfur battery; the amount of the lithium salt which can mainly form a film on the lithium cathode of the lithium-sulfur battery and the lithium salt which can mainly form a film on the sulfur anode of the lithium-sulfur battery is (1-10): 1; the mixed lithium salt is used for improving the lithium ion transmission performance of the electrolyte to the sulfur anode of the lithium-sulfur battery and improving the oxidation resistance of the electrolyte, thereby promoting the capacity exertion and the circulation stability of the sulfur anode and improving the potential window of the electrolyte.
2. The dilute lithium salt mixed lithium salt lithium sulfur battery electrolyte of claim 1 wherein the lithium salt capable of forming a film predominantly on the lithium negative electrode of a lithium sulfur battery is lithium bis (fluorosulfonyl) imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate or lithium perchlorate; the lithium salt mainly capable of forming a film on the sulfur positive electrode of the lithium-sulfur battery is lithium bistrifluoromethylsulfonyl imide, lithium difluorooxalate borate, lithium difluorophosphate or lithium dioxalate borate.
3. The diluted lithium salt mixed lithium-sulfur battery electrolyte of claim 2, wherein the lithium salt capable of forming a film predominantly on the lithium negative electrode of a lithium-sulfur battery is lithium bis (fluorosulfonyl) imide and the lithium salt capable of forming a film predominantly on the sulfur positive electrode of a lithium-sulfur battery is lithium bis (trifluoromethylsulfonyl) imide.
4. The diluted lithium salt mixed lithium sulfur battery electrolyte of claim 1, wherein the concentration of the mixed lithium salt in the electrolyte is 1mol/L to 10 mol/L.
5. The diluted lithium salt mixed lithium-sulfur battery electrolyte of claim 1, wherein the solvent dissolving the lithium salt is at least one of an ester solvent and an ether solvent.
6. The diluted lithium salt-mixed lithium-sulfur battery electrolyte according to claim 5, wherein the ester-based solvent is ethylene carbonate, dimethyl carbonate, diethyl carbonate, fluoro carbonate or propylene carbonate, and the ether-based solvent is ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran or 1, 3-dioxolane.
7. The diluted lithium mixed salt lithium-sulfur battery electrolyte of claim 1, wherein the ratio of the amount of the solvent dissolving the lithium mixed salt to the amount of the substance mixing the lithium salt is (1-20): 1.
8. The diluted lithium salt mixed lithium sulfur battery electrolyte of claim 1, wherein the diluent is at least one of a fluoroether-based compound and an aromatic-based compound.
9. The diluted lithium salt mixed lithium sulfur battery electrolyte according to claim 8, wherein the fluoroether-based compound is at least one of 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether, 2,2, 2-trifluoroethyl ether and hexafluoroisopropyl methyl ether, and the aromatic-based compound is at least one of benzene, halogenated benzene homolog, halogenated benzene isomer, alkane benzene homolog and alkane benzene isomer.
10. The diluted lithium mixed salt lithium sulfur battery electrolyte of claim 9, wherein the halogenated benzene is fluorobenzene, methylfluorobenzene, chlorobenzene, bromobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene or hexafluorobenzene; the halogenated benzene isomer is difluorobenzene isomer, trifluorobenzene isomer, tetrafluorobenzene isomer or methyl fluorobenzene isomer; the alkane benzene is toluene or ethylbenzene.
11. The diluted lithium salt-mixed lithium-sulfur battery electrolyte of claim 1, wherein the amount ratio of the diluent to the lithium salt-mixed material is (1-10): 1.
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| CN112382792A (en) * | 2020-10-31 | 2021-02-19 | 华南理工大学 | Fluoroether-containing electrolyte cosolvent for lithium metal/lithium ion/lithium sulfur battery, electrolyte and lithium secondary battery |
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| CN120999124A (en) * | 2025-09-12 | 2025-11-21 | 山东大学 | A far-oxygen-terminated fluorinated electrolyte, its preparation method, and its application in high-energy-density, long-life lithium metal batteries. |
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