Preparation And Characteristics Of Cathode Composite Materials Of GO@KB-S And GO@MKB-S By Spray Drying Process For Lithium-sulfur Batteries

Li-S battery,which owns a theoretical discharge capacity of 1675 mAh g^-1,catches the attention of scholars.If sulfur reacts completely during the electrochemical reaction process,the mass energy density and volume energy density of Li-S battery can approximately reach 2500 Wh kg^-1 and 2800 Wh L^-1.However,low utilization of positive materials and low cycling discharge performance have impeded the commercialization of Li-S battery.Sulfur-based cathode materials play an important role in affecting the electrochemical performance of Li-S battery.Owing to outstanding absorbtion of polysulfides by the functional groups on the surface area of GO,we successfully developed a spray drying method to prepare Graphene Oixed?GO?coating Ketjen Black-S composite powders?GO@KB-S?,which is a kind of cathode materials similar to the core-shell structure.The effects of different GO coating content on the electrochemical performance of Li-S battery were first carefully studied.Comparing the GO content from 0%to 15%,the prepared GO@KB-S composites with 10%GO coating appears the best performances.Actually,with a sulfur loading of 3 mg cm^-2,the 10%GO@KB-S cathode electrode reveals a high discharge capacity of 782.8 mAh g^-1 at 0.5 C.Furthermore,the discharge capacity of the 10%GO coating sample maintains 609.2 mAh g^-1 after 100 cycles and556.8 mAh g^-1 after 200 cycles.Meanwhile,the cycle retention of 10%GO coating sample is 77.82%after 100 cycles and 71.13%after 200 cycles.Additionally,the 2D nanosheet-like?-MnS has large polar,which can absorb polysulfides to hinder the diffusion and shuttle effect of polysulfides.In addition,?-MnS can catalyze the REDOX reaction of Li-S battery,improve the reaction kinetics,and accelerate the completion of charge and discharge.The?-MnS-KB composite powders?MKB?was prepared via a solvothermal reaction,then a spray drying method was used to obtain GO coating?-MnS-KB-S composites?GO@MKB-S?,and the GO content keeps 10%.The specific areas of MKB is 1157m² g^-1,and most pore diameter of MKB is 4 nm.With a sulfur loading of 5 mg cm^-2,the cathode electrode of GO@MKB-S shows a considerable discharge capacity of749.9 mAh g^-1 at 0.36 C,which is better than the cathode electrode of GO@KB-S.Additionally,after 100 cycles,the cycle retention rate of GO@MKB-S sample reaches 97.36%,after 200 cycles,the cycle retention rate of GO@MKB-S sample reaches 78.69%.