The mass transfer of polysulfide ions in composite micro-mesoporous carbon materials and its effect on electrochemical performance of lithium-sulfur batteries

Due to its high theoretical specific capacity, low cost and environmental benignancy, lithium-sulfur battery attracts lots of researcher’s attentions in recent days.However,before it fully commercialize, there are still several obstacles should be solved. Among them, the shuttle effect originating from the dissolved intermediate high order polysulfides, which diffuse between cathode and anode and result in a self-discharge, poor cyclic stability and fast capacity decay, is one of the most important hurdles. To tackle this challenge, here we propose to study the mass transfer process of the polysulfides inside the micro/meso-porous carbon materials and then design and synthesis of composite carbon materials, which are used as the conductive framework as well as the sulfur/lithium sulfide host. Based on the results of the literatures and our previous studies, we plan to obtain a hierarchical porous carbon materials with N/B/F doped on the surface associated the transition metal and/or transition metal oxides highly dispersed within the carbon matrix. Those composite carbon materials are expected to exhibit high interaction with polysulfide species. The mass transfer of the polysufides will be slow down then the process of the polysulfides diffusion away from the positive electrode will be impeded. In this project, we try to focus on the design and fabricate the composite carbon materials effectively, and in the mean time to realize the lithium sulfur battery with high power density and high cyclic stability.

Keywords:mass transfer of polysulfide, composite carbon material, Lithium-sulfur battery, shuttle effect, high cyclic stability

Project type:PhD project