Microstructure Design And Modification Of Cathode Materials For Lithium Sulfur Battery

Compared with traditional lithium ion battery,the lithium-sulfur battery is one of the most promising candidates as energy storage and power battery due to its high theoretical capacity.But there are a few challenges for the practical application and commercialization of Li-S batteries,including the poor electrical conductivity of sulfur and the large volume expansion during the discharge.To improve Li-S battery's performance,this paper mainly design different micro structures of cathode materials.At beginning,through different ways we synthesized sulfur nanopparticles.Then,we designed and gained the core shell structure of TiO₂@S and yolk shell structure of Pan@S composites by using sulfur nanopparticles as core.Many characterization techniques,such as scanning,transmission electron microscopy and X-Ray diffraction analysis,were used to investigate the prepared materials.In addition,the prepared materials were applied into Li-S battery to investigate the performance of cathode materials.Through exploring and improving different preparation processes,the sulfur nanoparticles with an average diameter of 500 nm were synthesised by using sodium thiosulfate to react with sulfuric acid.We fabricated the core shell structure of TiO₂@S composite by adjusting the pH and the amount of bis?2,4-pentanedionato?bis?2-propanoic?titannium.At 0.1 C,its initial discharge capacity is 1029.3 mA h g^-1.And still remain a high discharge capacity 512.5mA h g^-11 after 50 cycles at 0.1 C.Compared to C/S composite,the core shell structure of TiO₂@S composite has better cyclic stability and rate performance.Using ammonium persulfate as an initiator,the yolk shell structure of Pan@S was prepared by adjusting the molar ratio of sulfur nanoparticles and aniline.The results show that compared with C/S and Pan@S composites the yolk shell structure of Pan@S composite has better cyclic stability and rate performance.