Preparation Of Carbon/sulfur Composite Membrane For Energy Storage

Carbon materials has been an important part of energy storage and conversion devices.More attention has been paid on carbon materials using in energy storage since graphene was prepared successfully.As a macroscopical two-dimension form of carbon materials,carbon based membrane has an advantage of operability,which play an important role in flexible energy storage.However,fabrication of appropriate carbon based membrane and searching out its relevant application restricted its development.To overcome these problems,in this dissertation,starting with high dispersible sulfur,we manufactured GO/S membrane and CNT/S membrane with different sulfur content and explored possibility of applying in energy storage.In this thesis,the main contents include:After prepared the GO/S membrane with sulfur homogeneously distributed on graphene oxide sheet,we found that mechanical behavior of the membrane was promoted.Then we chose SiO₂ and TiO₂ to replace sulfur in the composite membrane,the same phenomenon was observed.So for the first time,we proposed a method to increase the mechanical behavior of graphene oxide based membrane,which was not chemical cross-linking.Besides,hydrophobicity of the CNT/S membrane was improved because of sulfur changing its porosity.Due to its good mechanical behavior,GO/S membrane was possible to apply in flexible supercapacitor aselectrodes.However,the mechanical behavior and hydrophily of GO/S was damaged after heat treatment,result in poor electrochemical performance in supercapacitor.To research suitable electrode materials for flexible supercapacitor,CNT was used to take place of sulfur in GO/S.We found that electrochemical performance of graphene based membrane applied in supercapacitor was greatly promoted,after GO/CNT membrane was reduced by HI acid to maintain its mechanical behavior and hydrophily.Porous structure and sparse netof CNT/S membrane was enhanced owing to sulfur uniformly distributed on carbon nanotubes,so we inserted CNT/S membrane between cathode and separator as a polysulfide barrier in lithium-sulfur battery.As a result,the CNT/S membrane suppressed the shuttle effect greatly,and the sulfur loading of the electrode was also increased because of sulfur content was easily controlled in CNT/S.Therefore,as a polysulfide barrier,CNT/S was beneficial to enhance the cycling stability of lithium-sulfur battery.