Core-shell structured S@CuO/delta-MnO2 composites as cathodes for lithium-sulfur batteries

The dissolution of polysulfides (LiPSs) always leads to low coulombic efficiency, dramatic capacity decay, and short cycle life, which hinder the practical application of lithium-sulfur (Li-S) batteries. In this study, we designed a CuO/delta-MnO2 shell to mechanically confine and chemically adsorb the soluble LiPSs, besides, delta-MnO2 may effectively catalyze the conversion of soluble LiPSs to insoluble Li2S2/Li2S, shortening the retention time of LiPSs and thus reduce their dissolution and shuttle. The core-shell structured S@CuO/delta-MnO2 composites have been successfully prepared by doping Cu2+ in the process of coating PDA on the surface of sulfur spheres, and then in situ generating delta-MnO2 on the surface of sulfur spheres through the redox reaction between KMnO4 and PDA. Finally, the as-prepared S@CuO/delta-MnO2 composites were used as cathodes for the Li-S battery and realized an improved electrochemical performance with an initial specific capacity of 848.1 mAh g(-1) at a current density of 0.1 C.