Active material infusion strategy dependent electrochemical performance of Se-S mixed cathode in Li-S batteries

Nitrogen containing mesoporous carbon spheres act as a host for Se-S mixed cathode in Li-sulfur batteries. We prepare 50 and 60 wt% of active material (Se-S) containing carbon spheres using a single and two step infusion method individually. Loading of 60 wt% Se-S mixed active material in carbon spheres using a two step infusion method exhibits crystalline nature, whereas single step infusion method yields amorphous product. Interestingly, Se and S involve in the electrochemical reaction with Li. Among the products, 60 wt% Se-S loaded carbon spheres from a two step infusion method effectively suppresses the active material against shuttling and retains about 528 and 387 mAh/g of capacity at C/10 and 1C rate respectively due to the better electronic conductivity and polar nature of ∼5% nitrogen present in the carbon sphere. Further, Se-S@carbon sphere cathode demonstrates better electrochemical performance than S or Se@carbon sphere cathodes. The study deals with the effect of mixed active material loaded carbon spheres and the role of infusion method in improving the electrochemical behaviour of Li-S system both individually and in synergy.