Lithium-ion batteries are widely used in people's daily life. With the development of society, traditional lithium-ion batteries are far from meeting people's needs for energy storage. Lithium-sulfur batteries (Li-S) are considered as one of the most promising high-capacity storage systems due to their high theoretical specific capacity and energy density, as well as the low cost and environmental friendliness of sulfur. However, there are still some technical challenges in the commercial application of Li-S batteries, such as the insulation properties of solid sulfides, the shuttle effect of soluble long-chain polysulfides, and the large volume change of sulfur during charge and discharge. These problems often lead to low sulfur utilization, poor cycle life, and even a series of safety issues. How to greatly improve the actual energy density and cycle stability of Li-S batteries has become one of the current research hotspots.
The separator is also one of the important components of the battery, and its role is to conduct ion transmission and prevent the battery from short-circuiting. Commercial PP separators, because of their larger pore diameters, allow polysulfides to pass through more easily, so they cannot effectively inhibit the diffusion and shuttle of polysulfides. Supported by the National Natural Science Foundation of China (21471151, 21673241) and the Strategic Leading Science and Technology Project of the Chinese Academy of Sciences (XDB20030200), Wang Ruihu, a researcher at the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Materials, Chinese Academy of Sciences, uses the catalytic effect of metal nanoparticles A porous carbon nanosheet composite material uniformly doped with cobalt and nitrogen was prepared by ion-exchange and high-temperature roasting technology using ionene-coated graphene oxide as a precursor. The composite-modified membrane not only can effectively prevent the polysulfide from shuttle through the membrane through physical / chemical action, but also can act as an electrocatalyst, further promoting the catalytic conversion of the intercepted polysulfide. Modified diaphragm assisted by catalytic effect, self-supporting electrode with high sulfur (10.5 mg cm-2) exhibits high discharge surface capacity (12.5 mA h cm-2) and volume specific capacity (1136 mA h) at 0.1 C cm-3). The electrochemical performance is better than most of the carbon-based positive electrode materials reported so far, and has achieved a synchronous increase in sulfur load, volume capacity, and area capacity of lithium-sulfur batteries, which is of great significance for the design and construction of high-energy density lithium-sulfur batteries.