Preparation And Performance Improvement Study Of Eletrodematerials For Lithium-sulfur Battery With High Specific Capacity

As one of the most competitive next generation of rechargeable batteries,lithium-sulfur(Li-S)batteries have attracted considerable attention due to their high theoretical energy density of 2600 Wh kg-1.In addition to high energy density,elemental sulfur as the cathode of Li-S batteries benefits from advantages of natural abundance,low cost and non toxic.The development of Li-S battery has a huge advantage.However,due to the restriction of current research level and technical level,the existing problems of lithium-sulfur battery have not been completely resolved.Specially,the "shuttle effect" is considered as one of the main obstacles,which can lead to capacity fast fading and low coulomb efficiency.In this study,for the "shuttle effect",multi-functional carbon paper and a novel gel polymer electrolyte(PEGPE)were prepared,which significantly improved the performance of lithium-sulfur battery.(1)For the "shuttle effect",we studied a multi-functional carbon paper barrier layer.The multi-functional carbon paper layer was fabricated by modifying the carbon paper coated with a conductive agent and a metal oxide.Then,this carbon paper was inserted between the positive electrode and the separator as a barrier,which can retain the movement of the dissolved polysulfide.Li-S battery equipped with carbon paper layer show excellent long-cycle performance(0.5 C,the initial discharge specific capacity of 1250 mAh g-1)and through the scanning electrode and elemental distribution map analysis,intuitive proof of the carbon paper barrier layer resistance to polysulfide.(2)In this paper,to solve the "shuttle effect",A novel GPE(PEGPE)supported by PE was prepared,which has many ester groups and uses pentaerythritol tetraacrylate(PETEA)as cross-linker to polymerize with divinyladipate(Ester),replacing the traditional liquid electrolyte in Li-S battery.The Li-S batteries with PEGPE showed an excellent cyclic stability and retained a reversible specific discharge capacity of 343 mAh g-1 after 300 cycles at 0.5 C rate,with approximately 92% coulombic efficiency.The good cyclability of this Li-S battery is due to the PEGPE blocking polysulfide shuttle and the extremely stable electrode/electrolyte interface.