Inhibiting shuttle effect of lithium polysulfides by double metal selenides for high-performance lithium-sulfur batteries

Lithium-sulfur batteries(LSBs) have attracted the attention of more and more researchers due to the advantages of high energy density,environmental friendliness,and low production cost.However,the low electronic conductivity of active material and shuttling effect of lithium polysulfides(LiPSs) limit the commercial development of LSBs.To solve these problems,we design a core-shell composite with nitrogen-doped carbon(NC) and two types of selenides(FeSe2-NC@ZnSe-NC).The FeSe2-NC@ZnSe-NC has a strong adsorption capacity,and can effectively adsorb LiPSs.At the same time,it also effectively alleviates the shuttling effect of LiPSs,and improves the utilization of the active substance during the charge/discharge reaction processes.The mechanism involved in FeSe2-NC@ZnSe-NC is demonstrated by both experiments and density-functional theory(DFT) calculations.The electrochemical test results indicate that LSB with S/FeSe2-NC@ZnSe-NC delivers an initial discharge capacity of 1260 mAh·g-1at 0.2C.And after 500 cycles at 1C,the capacity decay rate per cycle is 0.031%,and the capacity retention rate is 85%.The FeSe2-NC@ZnSe-NC core-shell structure verifies a rational strategy to construct an electrode material for high-performance LSBs.