Local high-concentration lithium-sulfur battery electrolyte

Abstract

The invention provides a local high-concentration lithium-sulfur battery electrolyte. The electrolyte is prepared from a solvent ethylene glycol dimethyl ether with a high donor number, dimethyl sulfoxide, 1, 3-dimethyl-2-imidazolinone, a diluent fluoro-ether with a low donor number and an amphiphilic surfactant perfluoroalkyl sulfonyl fluoride, the solvent with the high donor number dissolves lithium salt to form a high-concentration electrolyte solution, so that the free solvent is reduced; the fluoro-ether is used for diluting a high-concentration lithium salt solution to reduce the viscosity of the electrolyte; and the amphiphilic surfactant perfluoroalkyl sulfonyl fluoride is used for optimizing the spatial distribution of the high-concentration lithium salt, so that high-concentration lithium ions are uniformly distributed, and the electrochemical performance is improved. The local high-concentration electrolyte can reduce shuttling of soluble intermediate products of a lithium-sulfur battery, inhibit growth of lithium dendrites and improve the cycling stability and rate capability of the lithium-sulfur battery.

Description

technical field [0001] The invention relates to the field of lithium-sulfur batteries, in particular to a local high-concentration lithium-sulfur battery electrolyte that can inhibit lithium polysulfide shuttle and lithium dendrite growth. Background technique [0002] With the rapid development of new energy vehicles, electric drones and other large electric devices, there is an urgent need for rechargeable batteries with higher energy density. Lithium-sulfur batteries use sulfur as the positive electrode and lithium metal as the negative electrode. The theoretical capacities of the sulfur positive electrode and lithium negative electrode are 1675 and 3860 mAh / g, respectively. Lithium-sulfur batteries can provide a theoretical energy density of up to 2600 Wh / kg, which is eight times higher than that of current commercial lithium-ion batteries. At present, the energy density of lithium-sulfur batteries actually manufactured can reach 500-600Wh / kg, which is about twice that ...

AI Technical Summary

Problems solved by technology

[0006]The physical properties of the electrolyte solvent can limit the dissolution of lithium polysulfide in the electrolyte, and the low solubility of lithium salts in low-donating solvents limits the reaction of lithium-sulfur batteries power

The high-concentration electrolyte has no free solvent molecules, which can inhibit the dissolution of lithium polysulfide and the growth of lithium dendrites, but increases the cost of electrolyte preparation and reduces the ion conductivity

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