摘要
The practical application of lithium-sulfur(Li-S)batteries is hindered by the sluggish redox kinetics of sulfur,significant volume expansion,and the shuttle effect of lithium polysulfides(LiPSs).To address these challenges,this study utilizes hollow carbon spheres(HCS)as a matrix,incorporating a heterojunction of transition metal sulfides(CoS_(2)/MoS_(2))as the sulfur host.The HCS,with their ultrahigh specific surface area,effectively mitigate structural damage to the cathode caused by sulfur’s volume expansion during charge and discharge cycles.Meanwhile,the CoS_(2)/MoS_(2)heterojunction provides abundant chemical adsorption and reaction sites,which accelerate the redox kinetics of sulfur and alleviating the shuttle effect of LiPSs.Density functional theory(DFT)calculations reveal that the coupling effect at the CoS_(2)/MoS_(2)heterointerface significantly enhances charge transfer and adsorption interactions between CoS_(2)/MoS_(2)and LiPSs.Experimental results demonstrate that Li-S batteries with S/CoS_(2)/MoS_(2)@HCS composites as the cathode exhibit an exceptionally low capacity decay rate of only 0.023%per cycle after 1200 cycles at 2.0 C.Even with high sulfur loading(7.9 mg cm^(−2))and a low electrolyte-to-sulfur(E/S)ratio(6.0μL mg^(−1)),the battery achieves an outstanding areal capacity of 6.86 mA h cm^(−2).This study develops a highly efficient CoS_(2)/MoS_(2)heterojunction within HCS for the adsorption and conversion of LiPSs,providing valuable insights into the design of high-performance cathode materials for Li-S batteries.
基金
supported in part by the Institute for Advanced Study of Central South University and the High Performance Computing Center of Central South University。
