Electrolyte used for Li-S battery, Li-S battery and method for preparing electrolyte membrane contained in same

Abstract

The invention discloses an electrolyte used for a Li-S battery, comprising an electrolyte membrane and electrolyte, wherein the electrolyte membrane takes PVDF (polyvinylidene fluoride) or PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) as a main chain, the side chain of the main chain comprises one or more than one of lithium sulphonate group, lithium carboxylate group and lithium amide group; and the electrolyte is mixed solution containing at least one of 1,3-dioxolame, dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and sulfolane. The electrolyte, an anode and a cathode form the Li-S battery in the invention. The method for preparing the electrolyte membrane contained in the electrolyte comprises the following steps: firstly dissolving PVDF or PVDF-HFP, heating and stirring, and casting to obtain a membrane; treating the membrane with KOH / ethyl alcohol solution, then transferring the membrane into mixed solution of graft monomer / tetrahydrofuran, and adding formylamine peroxide for grafting; and cleaning the grafted membrane and soaking to obtain the electrolyte membrane. The electrolyte membrane in the invention is simple to prepare,the cost is low, the loss of active substance can be reduced, and the cycle life of the battery can be prolonged.

Description

technical field [0001] The invention relates to a preparation method of an electrolyte membrane in a secondary battery, an electrolytic cell and an electrolyte, in particular to a preparation method of an electrolyte membrane in a secondary battery, an electrolytic cell and an electrolyte with a sulfur-containing material as a positive electrode. Background technique [0002] With the growing demand for smaller portable electronic devices such as camcorders, portable communication devices and portable computers, the demand for batteries with larger capacity, lighter and thinner is also growing rapidly, and the demand for such batteries Research and development is also being carried out on a large scale. Conventional Li-ion secondary batteries utilize transition metal oxides such as LiCoO 2 and LiMnO 2 ) as the positive electrode active material and carbon as the negative electrode active material. The theoretical gram capacity of carbon is 372 mAh / g, while transition meta...

AI Technical Summary

Problems solved by technology

However, the scale of use of Li-S batteries is still small today, one of the reasons is that the reaction between polysulfides and lithium metal leads to shortened battery cycle life, that is, sulfur molecules form polysulfide anions during battery discharge, when using When lithium metal is used as the negative electrode active material, polysulfide anions pass through the separator and directly react with lithium metal, so it is difficult to obtain high utilization of sulfur

Images