Progress in the research of lithium sulfur battery separator materials in Fujian Institute of physical structure

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 demand for energy storage. Lithium sulfur battery (li-s) is regarded as one of the most promising high-capacity storage systems because of its high theoretical specific capacity and energy density, as well as its low cost and environment-friendly advantages. However, there are still some technical challenges in the commercial application of li-s battery, such as the insulation of solid sulfide, the shuttle effect of soluble long-chain polysulfides, and the large volume change of sulfur during charging and discharging. These problems usually lead to low utilization rate of sulfur, poor cycle life, and even a series of safety problems. How to greatly improve the actual energy density and cycle stability of li-s battery has become one of the current research hotspots.

Diaphragm is also one of the important components of battery. Its function is to conduct ion transmission and prevent battery short circuit. Commercial PP diaphragms can not effectively inhibit the diffusion and shuttle of polysulfides because of their large pore size and easy passage of polysulfides. Supported by the National Natural Science Foundation of China (21471151, 21673241) and the special program of strategic leading science and technology of the Chinese Academy of Sciences (xdb20030200), Wang Ruihu, a researcher at the State Key Laboratory of structural chemistry, Fujian Institute of material structure, Chinese Academy of Sciences, made use of the catalytic effect of metal nanoparticles, and used ionic polymer coated graphene oxide as the precursor to prepare cobalt Nitrogen uniformly doped porous carbon nano sheet composites. The composite modified diaphragm can not only effectively block the shuttle of polysulfides through the diaphragm through physical / chemical action, but also act as an electrocatalyst to further promote the catalytic conversion of intercepted polysulfides. Modified diaphragm assisted by catalytic effect, high sulfur loading (10.5 mg cm^-2）The self-supporting electrode shows a high discharge surface capacity (12.5 Ma h cm) at 0.1 C^-2）And volume specific capacity (1136 Ma h cm^-3）。 This electrochemical performance is better than most carbon based cathode materials reported at present, and realizes the synchronous improvement of sulfur load, volume capacity and area capacity of lithium sulfur battery, which is of great significance to the design and construction of high energy density lithium sulfur battery.

The above research results were recently published in advanced energy materials（Adv. Energy Mater. 2019, September, 1901609), the first author of the paper is chengzhibin.