Lithium sulfur battery membrane material and application thereof

Abstract

The invention relates to a lithium sulfur battery membrane material and application thereof. The membrane material is obtained by smearing a mixed slurry of a catalyst, a conductive agent and a binder on the surface of polypropylene and then conducting drying, and is in a micrometer grade; the catalyst is metal oxide, metal nitride, metal sulfide or a metal simple substance; the conductive agent is acetylene black, ketjen black or a carbon nanotube; the binder is polyvinylidene fluoride, polyvinylidene difluoride, polyethylene oxide or polyacrylic acid. The conductive agent and the catalyst are all in the micrometer grade. The membrane can effectively stop polysulfide ions from diffusing from a negative electrode, so that the polysulfide ions aggregate on the surface on the membrane, and the catalyst can activate the polysulfide ions, and improve the actual specific capacity and the cycling stability. The lithium sulfur battery prepared by adopting the lithium sulfur battery membrane material has the advantages of being high in performance, long in service life and high in safety.

Description

technical field [0001] The invention relates to a functional diaphragm and its application in lithium-sulfur batteries, belonging to the field of electrochemical batteries. Background technique [0002] With the continuous development of science and technology and society, people's demand for new energy continues to increase. Emerging markets such as electric vehicles and smart grids have put forward higher requirements for new energy systems, especially in the field of electric vehicles. The energy density of power batteries is required to reach 500 Wh kg -1 above. However, the energy density of today's commercial lithium-ion batteries is limited by traditional cathode materials (LiCoO 2 , LiMn 2 o 4 、LiFePO 4 etc.) and the limitation of the theoretical capacity of the carbon anode material itself, it can only reach 150-200 Wh kg -1 . 350-400 Wh kg -1 It is close to the limit of the energy density of lithium-ion batteries, and it is difficult to further improve it. ...

AI Technical Summary

Problems solved by technology

However, the energy density of today's commercial lithium-ion batteries is limited by traditional cathode materials (LiCoO 2 , LiMn 2 o 4 、LiFePO 4 etc.) and the limitation of the theoretical capacity of the carbon anode material itself, it can only reach 150-200 Wh kg -1

350-400 Wh kg -1 It is close to the limit of the energy density of lithium-ion batteries, and it is difficult to further improve

[0005] As a separator material, it must have certain porosity, flexibility, shrinkage, wettability and ionic conductivity. At present, most of the commonly used lithium-sulfur battery separators are traditional olefin separators, mainly polypropylene (PP) microporous membranes. , polyethylene (PE) microporous membrane and multi-layer composite diaphragm (PP / PE two-layer composite or PP / PE / PP three-layer composite) produced by Celgard. The production cost of polyolefin diaphragm is low and the size of the pore size is controllable. It has good chemical and electrochemical stability and good mechanical strength, but its thickness, strength, and porosity are difficult to balance, and its high temperature resistance and high current charge and discharge performance are poor, so there is a huge problem when it is applied to power lithium sulfur batteries. Security risks

At the same time, due to the complexity of the charge-discharge reaction process and the diversity of electrolytes in lithium-sulfur batteries, traditional polyolefin separators cannot well inhibit the diffusion of polysulfides, an intermediate product of lithium-sulfur batteries. Therefore, the development of higher-quality separator materials is also Become one of the important directions to improve the overall performance of lithium-sulfur batteries

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