CN-121215884-B - Gel solid electrolyte for lithium sulfur battery, lithium sulfur battery and preparation method

CN121215884BCN 121215884 BCN121215884 BCN 121215884BCN-121215884-B

Abstract

The invention discloses a gel solid electrolyte for a lithium-sulfur battery, the lithium-sulfur battery and a preparation method thereof, and belongs to the technical field of lithium-sulfur batteries. The preparation method of the gel solid electrolyte comprises the following steps of ball milling and mixing LiFNFSI and LiWSI, annealing to obtain mixed lithium salt A, mechanically mixing with 2-isocyanatoethyl acrylate to obtain a mixture B, dissolving the mixture B in EC and DME, adding lithium nitrate and 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether to obtain a precursor C, refrigerating, adding tridecafluorooctyl triethoxysilane and an initiator to obtain a precursor D, and finally injecting the precursor D into a lithium sulfur battery to perform in-situ gel curing to obtain the gel solid electrolyte. The gel solid electrolyte solves polysulfide shuttle effect, realizes solid phase reaction from sulfur anode to lithium sulfide, and improves circulation stability and energy density.

Inventors

LIU GUOFENG
YANG HUI
CHEN DONGXU
WANG YONGZHONG
SHU YONG
CHEN ZHAOFAN
WANG YIDING
YUE PEIYU
WANG MENG

Assignees

中国铁塔股份有限公司

Dates

Publication Date: 20260512
Application Date: 20251128

Claims (10)

1. The preparation method of the gel solid electrolyte for the lithium-sulfur battery is characterized by comprising the following steps of: ball-milling and mixing (fluorosulfonyl) (n-perfluorobutylsulfonyl) lithium imine and lithium difluorosulfonyl imide to obtain a ball-milling mixture, and annealing the ball-milling mixture to obtain a mixed lithium salt A, wherein the mass ratio of (fluorosulfonyl) (n-perfluorobutylsulfonyl) lithium imine to lithium difluorosulfonyl imide is 1:1-3, the heating rate of the annealing treatment is 3-5 ℃ per minute, the annealing temperature is 200-500 ℃, and the heat preservation time is 1-5h; mechanically mixing the mixed lithium salt A with 2-isocyanatoethyl acrylate to obtain a mixture B; after the mixture B is dissolved in a mixed solution of solvent ethylene carbonate and ethylene glycol dimethyl ether, lithium nitrate and 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether are added into the mixed solution to obtain a precursor C; After the precursor C is refrigerated, adding tridecafluorooctyl triethoxysilane in a refrigerated environment for freezing and light-shielding stirring, and then adding an initiator for stirring to obtain gel solid electrolyte precursor D; and injecting the gel solid electrolyte precursor solution D into the lithium sulfur battery to perform gel curing in situ, so as to obtain the gel solid electrolyte for the lithium sulfur battery.
2. The method for producing a gel solid electrolyte for a lithium-sulfur battery according to claim 1, wherein the mass ratio of the mixed lithium salt to the 2-isocyanatoethyl acrylate is 1:2-5; And/or, the lithium nitrate accounts for 0.2-2% of the total mass of the precursor C; and/or, the 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether accounts for 10-50% of the total mass of the precursor C.
3. The method for preparing a gel solid electrolyte for a lithium sulfur battery according to claim 1, wherein the tridecafluorooctyltriethoxysilane accounts for 0.5-5% of the total mass of the gel solid electrolyte precursor solution D; and/or the initiator accounts for 0.2-0.5% of the total mass of the gel solid electrolyte precursor liquid D.
4. The method for preparing a gel solid electrolyte for a lithium-sulfur battery according to claim 1, wherein the ball-milling mixing speed is 5000-10000r/min for 10-90min; and/or the rotation speed of the mechanical mixing is 20000-30000r/min, and the time is 5-20min.
5. The method for preparing a gel solid electrolyte for a lithium sulfur battery according to claim 1, wherein the gel is cured at a temperature of 40 to 70 ℃ for a time of 12 to 48 hours.
6. A gel solid electrolyte for lithium sulfur battery, characterized by being produced by the production method of the gel solid electrolyte for lithium sulfur battery according to any one of claims 1 to 5.
7. A lithium-sulfur battery comprising the gel solid electrolyte for a lithium-sulfur battery according to claim 6.
8. A method of making a lithium sulfur battery as defined in claim 7 comprising the steps of: assembling a lithium sulfur battery positive electrode, a lithium metal negative electrode and a diaphragm into a soft-package dry battery; injecting the gel solid electrolyte precursor solution D in the claim 1 into the soft-package dry battery, sealing the soft-package dry battery after the injection, and placing the soft-package dry battery in a refrigerating environment for formation to obtain a formation cell; And (3) performing gel curing on the formed battery cell to obtain the lithium-sulfur battery.
9. The method for preparing a lithium-sulfur battery according to claim 8, wherein the formation temperature is 30-60 ℃ for 24-72 hours; and/or the gel is solidified at a temperature of 40-70 ℃ for 12-48 hours.
10. The method for preparing the lithium sulfur battery according to claim 8, wherein the lithium sulfur battery anode is a carbon sulfur anode plate, and the carbon sulfur anode plate is prepared by the following method: Mixing sulfur and a first carbon conductive agent, sequentially performing first ball milling, sealing and sintering to obtain a sintered material; performing second ball milling on the sintered material to obtain a carbon-sulfur composite material; stirring and mixing the carbon-sulfur composite material, an adhesive, a second carbon conductive agent and a solvent to obtain slurry; and (3) coating the slurry on the surface of a current collector, and sequentially drying and rolling to obtain the carbon-sulfur positive plate.

Description

Gel solid electrolyte for lithium sulfur battery, lithium sulfur battery and preparation method Technical Field The invention belongs to the technical field of lithium sulfur batteries, and particularly relates to a gel solid electrolyte for a lithium sulfur battery, the lithium sulfur battery and a preparation method. Background The gram capacity of the lithium-sulfur battery can be 1675 mAh/g, the energy density can be 2600 Wh/kg, in addition, the sulfur simple substance is cheap, the safety is high, the battery for base station power preparation is extremely friendly, the safety risk of the battery pack for base station power preparation is hopefully thoroughly solved, and the battery pack for base station power preparation becomes a high specific energy battery for the next generation of large-scale application. However, the lithium sulfur battery in the present stage has the problem that the electrolyte in the lithium sulfur battery has high solubility to polysulfides generated by charge and discharge, and the generated mesophase polysulfides are caused to leave the surface of the positive electrode to form a shuttle effect, so that the electrochemical activity of the mesophase polysulfides is lost. In addition, the shuttle polysulfide and lithium metal of the negative electrode can generate chemical reaction, and the surface of the negative electrode is blunt, so that the cycle life and the rate capability of the battery are further restricted under the condition of active material loss, and the energy density of the lithium-sulfur battery cannot be improved. In view of the above problems, conventional solutions mainly include adding a polar group to the positive electrode or coating a carbon material on the separator to buffer polysulfide dissolution and shuttling. For example, application number CN201810810039.8 discloses a lithium-based montmorillonite@sulfur composite material, a preparation method and application thereof, and the shuttle problem of polysulfide is relieved and the circulation stability of a sulfur anode is improved by introducing the lithium-based montmorillonite into the interior. Although the above method can improve the cycle stability of the battery to a certain extent, the generation of polysulfide cannot be fundamentally avoided, and further, the formation of shuttle effect cannot be fundamentally inhibited. Therefore, the design of the electrolyte basically changes the electrochemical reaction path of sulfur, which is a key point for improving the cycle stability of the lithium-sulfur battery. At present, researches show that the reaction path of polysulfide can be fundamentally changed by adopting ester electrolyte, and solid phase reaction from sulfur to lithium sulfide conversion is realized. In 2018 Linda f. Nazar, professor NAT ENERGY, 783-791 (2018) proposes a sulfur conversion method of quasi-solid reaction, and a partial network of electrolyte is designed to form a fluorinated ether system electrolyte by using diethylene glycol dimethyl ether, so that the solid phase reaction of a sulfur positive electrode is realized, however, the prepared battery can realize normal charge and discharge only at high temperature due to low ionic conductivity and low activity of electrolyte, and practical application is restricted. Patent number CN106816633B discloses a pseudo high-concentration ester lithium sulfur battery electrolyte and a lithium sulfur battery, wherein the electrolyte contains lithium salt, an ester solvent and a non-solvent solution, the concentration of the lithium salt in an 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 0.5mol/L. The electrolyte can solve the problems of high viscosity and low conductivity of lithium-sulfur battery electrolyte using high-concentration lithium salt, radically changes the reaction path of polysulfide and realizes solid-phase reaction. However, the compatibility of the ester electrolyte with lithium metal is poor, and the reversibility of lithium sulfide in the ester electrolyte severely restricts the application of the ester electrolyte in lithium sulfur batteries, so that the ester electrolyte is still not the optimal choice of the lithium sulfur battery electrolyte. In addition, because the liquid electrolyte is adopted, the lithium sulfur battery has the advantages of high fluidity, low ignition point, low flash point, inflammability, explosiveness and other potential safety hazards when meeting conditions such as high temperature, and therefore the safety of the lithium sulfur battery is limited. Compared with the traditional liquid electrolyte, the gel electrolyte has better thermal stability and mechanical property, and is not easy to cause safety problems such as leakage, combustion and the like. According to the application number CN202110518906.2, a polymer film is obtained by adding a high molecular monomer, and fi