Lithium-sulphur battery diaphragm preparation method, lithium-sulphur battery diaphragm and lithium-sulphur battery

Abstract

The invention relates to the field of lithium-sulphur batteries, and provides a lithium-sulphur battery diaphragm preparation method. The lithium-sulphur battery diaphragm preparation method comprises the four steps of: simultaneously adding chemical staple fibre and separated and wrinkled micro-fibre into a solvent; after free deposition of matrix slurry, coating uniformly dispersed nano-cellulose slurry on the surface of a matrix; after nano-cellulose is formed, coating conductive polymer and nano-cellulose composite slurry on the surface, finally, squeezing, and drying to form the diaphragm; and, hot pressing and cutting the diaphragm. According to the lithium-sulphur battery diaphragm preparation method provided by the invention, the lithium-sulphur battery diaphragm can be obtained through the steps S1-S4; and thus, the coulombic efficiency of the lithium-sulphur battery can be improved. The invention provides a lithium-sulphur battery diaphragm comprising an intermediate layer, a basal layer and a surface layer. The lithium-sulphur battery diaphragm provided by the invention can store a lot of electrolyte; and thus, the battery cycle capacity is improved. The invention provides a lithium-sulphur battery comprising the diaphragm. The performance of the lithium-sulphur battery provided by the invention is greatly improved.

Description

technical field [0001] The invention relates to the field of lithium-sulfur batteries, in particular to a preparation method of a lithium-sulfur battery separator, a lithium-sulfur battery separator and a lithium-sulfur battery. Background technique [0002] In the lithium-sulfur battery system, metal lithium is used as the negative electrode and elemental sulfur is used as the positive electrode. The theoretical specific energy can reach 2600Wh / kg, which is much larger than modern commercial lithium-ion batteries. In addition, elemental sulfur also has the characteristics of low price and environmental friendliness. Therefore, lithium-sulfur batteries have high potential for commercial application. However, lithium-sulfur batteries also have many problems. The most important of these is that during the charge and discharge process of lithium-sulfur batteries, the utilization rate of sulfur is low, and the capacity decays rapidly during the cycle. The reasons for this prob...

AI Technical Summary

Problems solved by technology

[0003] The serious problems existing in the existing lithium-sulfur batteries are summarized as follows: First, the conductivity of sulfur and lithium sulfide is low, and it is usually necessary to add graphite, graphene, and carbon tubes to the positive electrode to enhance the conductivity, and the sulfur particles are charged and discharged. A large change in volume occurs during the process, and such a change will destroy the electrode structure; second, the generated intermediate polysulfide is highly soluble in the organic electrolyte, resulting in active material loss and energy consumption; third, the dissolved polysulfide The substances will diffuse to the cathode and react with the lithium cathode, forming discharge products, or forming precipitates on the surface of the lithium cathode; fourth, the dissolved polysulfides are prone to shuttle effect, and the shuttle effect and the precipitation on the surface of the lithium cathode will lead to Low utilization rate of sulfur, low coulombic efficiency and fast capacity fading of sulfur cathode

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