| With the increasing demand of the world energy consumption, Li-ion batteries (LIBs) have been widely used as the primary electrical energy storage devices in various portable electronics for their lightweight relative to other types of batteries. With high theoretical capacity of1675mA h g-1, natural abundance, low cost, and environmental friendliness, elemental sulfur has been considered as one of the most promising alternative cathode materials. However, the Li-S battery systems investigated previously have some persistent problems, like low utilization and poor cycle capability.To overcome these problems, many attempts have been made, which focus on enhancing the electrical conductivity of the cathode and suppressing the loss of soluble polysulfide intermediates during cycling. On the basis of the aforementioned studies, it is evident that porous carbon/sulfur composites, especially for mesoporous carbon, can yield a much improved electro-chemical activity and cycling stability. The main research contents and results are as follows:(1) Design and synthesize ordered mesoporous carbon-sulfur composites with conductive polymers introduced, to examine the effect of mesoporous carbon and conductive polymer through the electrochemical performance of the composites. Found that with the mesoporous carbon, elemental sulfur particles can be reduced to the nanoscale, and the composites coated with polypyrrole can effectively inhibit the shuttle effect, raising the electrode capacity.(2) Preparation of peapodlike mesoporous carbon with large pore volume to construct the carbon-sulfur composite, which sulfur loading is up to84wt%. Using conductive polymer coated carbon-sulfur multiple composite to prove that the polypyrrole coated layer can effectively reduce the dissolution of polysulfides, curb the loss of the active substance, and then get a good cycle stability, with the specific capacity of719mA h g-1after50cycles. Explore different capacity calculation methods and analyze the decay rate. |
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