CeO2 decorated graphene as separator modification material for capture and boost conversion of polysulfide in lithium-sulfur batteries

The commercialization of lithium-sulfur (Li-S) batteries is hindered by the poor electrochemical performance which mainly originates from the shuttle of polysulfides and the loss of active sulfur. In this work, a multi-functional separator modified by CeO2 decorated graphene (CeO2@G) is designed to enhance the performance of Li-S batteries. The CeO2 nanoparticles not only immobilize polysulfides by strong chemisorption, but also act as catalytic agent to accelerate polysulfides redox reaction. Moreover, the highly conductive graphene sheets functioned as an upper current collector to improve the electron/ion conductivity and facilitate the reutilization of sulfur species. As a result, the Li-S battery with the CeO2@G modified separator delivers high specific capacity (1546 mAh g-1 at 0.2 A g-1), excellent rate performance (861 mAh g-1 at 3 A g-1), and long-term cycle durability (480 mAh g-1 at 5 A g-1 after 1000 cycles). In addition, the modified separator can effectively against the self-discharge behavior. The outstanding electrochemical performance brings us a closer step towards practical applications of Li-S batteries.