CN-122025840-A - Preparation method and application of lithium sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethyl pyridine

Abstract

The invention provides a preparation method and application of a lithium sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethyl pyridine, belonging to the technical field of chemical energy storage batteries, the lithium sulfur battery electrolyte containing the 2-hydroxy-6-trifluoromethyl pyridine is obtained by adding the 2-hydroxy-6-trifluoromethyl pyridine into the ether lithium sulfur battery basic electrolyte and sealing and stirring the solution. The invention utilizes the hydroxyl and trifluoromethyl contained in the 2-hydroxyl-6-trifluoromethyl pyridine, can regulate and control the positive side polysulfide behavior and the negative side SEI composition simultaneously when being used as the additive of the lithium sulfur battery electrolyte, and forms the synergistic closed-loop effect of 'positive side shuttle inhibition and negative side reinforcing SEI', thereby further improving the interface stability and the battery coulomb efficiency and reducing the capacity attenuation.

Inventors

• TAO SILU
• KANG YAOWEN

Assignees

• 电子科技大学

Dates

Publication Date

20260512

Application Date

20260225

Claims (6)

1. 1. The preparation method of the lithium sulfur battery electrolyte containing the 2-hydroxy-6-trifluoromethyl pyridine is characterized by comprising the following steps of: step 1, preparing a basic electrolyte of an ether lithium-sulfur battery; And 2, adding 2-hydroxy-6-trifluoromethylpyridine into the ether lithium sulfur battery base electrolyte, and sealing and stirring to obtain the lithium sulfur battery electrolyte containing the 2-hydroxy-6-trifluoromethylpyridine.
2. 2. The method for preparing the lithium sulfur battery electrolyte containing the 2-hydroxy-6-trifluoromethylpyridine according to claim 1, wherein the concentration of the 2-hydroxy-6-trifluoromethylpyridine in the lithium sulfur battery electrolyte obtained in the step 2 is 0.1-10wt%.
3. 3. The method for preparing the lithium sulfur battery electrolyte containing the 2-hydroxy-6-trifluoromethylpyridine according to claim 1, wherein in the step 2, a small amount of ether lithium sulfur battery basic electrolyte is used for prewetting the 2-hydroxy-6-trifluoromethylpyridine, and then the prewetted 2-hydroxy-6-trifluoromethylpyridine is added into the rest ether lithium sulfur battery basic electrolyte, so that caking of the 2-hydroxy-6-trifluoromethylpyridine is reduced and dissolution is accelerated.
4. 4. The preparation method of the lithium sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine is characterized in that the specific process of the step 1 is that lithium salt and LiNO 3 are dissolved in a DOL/DME mixed solution with the volume ratio of 1:9-9:1, the concentration of the lithium salt in the ether lithium sulfur battery basic electrolyte is 0.2-3 mol/L, and the concentration of LiNO 3 is 0.1-10 wt%.
5. 5. A lithium sulfur battery using the lithium sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethylpyridine obtained by the preparation method of any one of claims 1 to 4.
6. 6. The lithium sulfur battery according to claim 5, wherein the electrolyte of the lithium sulfur battery containing 2-hydroxy-6-trifluoromethylpyridine is added at 15-50 mu L respectively at two sides of the diaphragm, and the total amount is 30-100 mu L.

Description

Preparation method and application of lithium sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethyl pyridine Technical Field The invention belongs to the technical field of chemical energy storage batteries, and particularly relates to a preparation method and application of a lithium sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethyl pyridine. Background Under the push of the background of double carbon and the requirement of renewable energy grid connection, the high specific energy secondary battery becomes an important support for energy storage and traffic electric drive. Lithium sulfur batteries have been attracting attention because of their advantages of abundant sulfur resources, high theoretical specific capacity, high theoretical energy density, and the like. However, the lithium sulfur battery still faces the comprehensive problems of polysulfide shuttle effect, active material loss, serious interface side reaction, insufficient rate capability and the like in practical application. Specifically, in a common ether electrolyte (such as DOL (1, 3-dioxolane)/DME (1, 2-dimethoxyethane) system), long-chain lithium polysulfide (Li 2Sx, 4<x is less than or equal to 8) generated in the discharging process has certain solubility, can diffuse in the electrolyte, can migrate to the surface of a lithium cathode through a diaphragm under the driving of an electric field, is reduced and deposited and causes continuous side reaction consumption, and can be reoxidized and returned to the positive electrode side in the charging process to form a typical shuttle cycle. The charge and discharge processes described above result in reduced coulomb efficiency, rapid capacity decay and significant self-discharge. In addition, the interfacial chemistry on the lithium negative electrode side in a lithium-sulfur system is particularly complex, and the interfacial chemistry is particularly characterized in that a coupling reaction occurs near the interface between a solvent, lithium salt anions, polysulfide, nitrate and the like, and if the formed SEI (solid electrolyte interface film)/deposition layer is not compact or stable, local current density unevenness is caused, so that uneven deposition and polarization rise of lithium are induced. In order to solve the above problems, the prior art generally adopts strategies such as positive limit field, multifunctional membrane, catalytic/adsorption material, electrolyte engineering (high concentration/local high concentration, functional additives, etc.), and the like. The functional additive strategy has high practical value because of small change to the existing system, simple process and capability of rapidly realizing performance improvement. However, the common additives have the problems of narrow effective window, insufficient compatibility, side effects on ion transmission and interface reaction, and the like, so that a new molecular structure and a new action mode still need to be developed to realize selective regulation and control on polysulfide behavior and interface reaction. Disclosure of Invention Aiming at the problems of strong lithium polysulfide shuttle effect, serious lithium negative electrode side reaction, low coulomb efficiency, short cycle life, obvious self-discharge and the like in the prior art, the invention provides a preparation method and application of a lithium sulfur battery electrolyte containing 2-hydroxy-6-trifluoromethyl pyridine, so as to realize regulation and control of polysulfide solvation/migration and improvement of electrode interface stability. The technical scheme adopted by the invention is as follows: The preparation method of the lithium sulfur battery electrolyte containing the 2-hydroxy-6-trifluoromethyl pyridine comprises the following steps: step 1, preparing a basic electrolyte of an ether lithium-sulfur battery; And 2, adding 2-hydroxy-6-trifluoromethylpyridine into the ether lithium sulfur battery base electrolyte, and sealing and stirring to obtain the lithium sulfur battery electrolyte containing the 2-hydroxy-6-trifluoromethylpyridine. Further, the specific process of the step 1 is that lithium salt and LiNO 3 are dissolved in DOL/DME mixed solution with the volume ratio of 1:9-9:1, the concentration of the lithium salt in the ether lithium sulfur battery basic electrolyte is 0.2-3 mol/L, and the concentration of LiNO 3 is 0.1-10wt%. Preferably, the volume ratio of DOL to DME is 1:1, the concentration of lithium salt is 1mol/L, and the concentration of LiNO 3 is 2: 2 wt%. The term "wt%" refers to the mass of a component as a percentage of the total mass of the component and other components of the electrolyte (e.g., additive mass/(additive mass+base electrolyte mass) ×100%). Further, the lithium salt is LiTFSI (lithium bis (trifluoromethylsulfonyl imide)) or LiFSI (lithium bis (fluorosulfonyl imide)). Further, the concentration of the 2-hydroxy-6-trifluoromethyl pyridine in the lithium