Bidirectional enhancement of Li2S redox reaction by NiSe2/CoSe2-rGO heterostructured bi-functional catalysts

The high activity barriers of Li 2 S nucleation and deposition limit the redox reaction kinetics of lithium polysulfides (LiPSs), meanwhile, the significant shuttle effect of LiPSs hampers the advancement of Li-S batteries (LSBs). In this work, a NiSe 2 /CoSe 2 -rGO (NiSe 2 /CoSe 2 -G) sulfur host with bifunctional catalytic activity was prepared through a hard template method. Electrochemical experiment results confirm that the combination of NiSe 2 and CoSe 2 not only facilitates the bidirectional catalytic function during charge and discharge processes, but also increases the active sites toward LiPSs adsorption. Simultaneously, the highly conductive rGO network enhances the electronic conductivity of NiSe 2 /CoSe 2 -G/S and provides convenience for loading NiSe 2 /CoSe 2 catalysts. Benefitting from the exceptional catalytic-adsorption capability of NiSe 2 /CoSe 2 and the presence of rGO, the NiSe 2 /CoSe 2 -G/S electrode exhibits excellent electrochemical properties . At 1C, it demonstrates a low capacity attenuation of 0.087 % per cycle during 500 cycles. The electrode can maintain a discharge capacity of 927 mAh/g at a sulfur loading of 3.3 mg cm −2 . The bidirectional catalytic activity of NiSe 2 /CoSe 2 -G offers a prospective approach to expedite the redox reactions of active S, meanwhile, this work also offers an ideal approach for designing efficient S hosts for LSBs.