A self-supporting functional interlayer for lithium-sulfur batteries and its preparation method

Abstract

The invention relates to a functional interlayer for lithium-sulfur batteries and a preparation method thereof. Using MAX phase ceramic powder as raw material, nitrogen-doped MXene was first prepared, and then the nitrogen-doped MXene composite copper sulfide self-supporting film was prepared by hydrothermal reaction. The preparation method not only simplifies the preparation process of the functional interlayer, but also avoids the comminution and shedding of effective components from the diaphragm during the cycle of the battery after coating in the traditional method. The nitrogen-doped MXene composite copper sulfide self-supporting film used as a functional interlayer of a lithium-sulfur battery has the characteristics of good conductivity, large specific surface area, many storage sites, and high rate performance, and can absorb polysulfide lithium, effectively Reduce the loss of active substances.

Description

technical field [0001] The technical solution of the present invention relates to a functional interlayer for lithium-sulfur batteries and a preparation method thereof, in particular to a nitrogen-doped MXene composite copper sulfide self-sulphide prepared by first preparing nitrogen-doped MXene and then utilizing hydrothermal reaction. A supported thin film and a method thereof belong to the field of materials chemistry. Background technique [0002] The development of new energy vehicles has put forward higher and higher requirements on the performance of batteries. It is of great significance to develop new lithium-ion secondary energy storage batteries with high specific energy and environmental friendliness. Elemental sulfur has the highest specific capacity, in lithium / sulfur (Li / S) batteries, its theoretical specific capacity is as high as 1675 mAh g -1 , the theoretical specific energy is 2600 Wh kg -1 , than LiCoO in conventional Li-ion batteries 2 Waiting for th...

AI Technical Summary

Problems solved by technology

[0003] Although lithium-sulfur batteries have been studied for decades, and some research results have been obtained in recent years, there is still a certain distance from the realization of industrialization.

There are some serious problems in the charging and discharging process of lithium-sulfur batteries. First, the conductivity of sulfur and lithium sulfide is low, and the volume of sulfur particles changes greatly during the charging and discharging process. Such changes will destroy the electrode structure; second, The generated intermediate polysulfide is highly soluble in the organic electrolyte, resulting in the loss of active materials and energy consumption; third, the dissolved polysulfide will diffuse to the cathode and react with the lithium cathode, forming a discharge product Li 2 S or Li 2 S 2 It will form a precipitate on the surface of the lithium cathode; fourth, the dissolved polysulfide is prone to shuttle effect

The shuttle effect and precipitation on the surface of the lithium cathode lead to low sulfur utilization, low coulombic efficiency and fast capacity fading of the sulfur cathode

In order to solve these problems, researchers at home and abroad have adopted many methods. Among them, adding a functional interlayer to the lithium-sulfur battery is an effective and simple method. The functional interlayer is placed between the positive electrode and the separator. It can physically or chemically fix the shuttling effect of polysulfides, which improves the utilization rate of positive active materials, thereby improving the overall performance of lithium-sulfur batteries. However, the traditional coating method is not practical in practice. In the application process, there are problems such as complex preparation process, difficult operation, and effective component falling off

Images