The facile synthesis and enhanced lithium–sulfur battery performance of an amorphous cobalt boride (Co2B)@graphene composite cathode

Abstract

Rechargeable lithium–sulfur (Li–S) batteries have attracted extensive attention as next-generation energy storage devices, owing to their high theoretical energy density, environmental benignancy, and cost effectiveness. However, the commercial application of Li–S batteries is limited because of the severe polysulfide shuttle effect, the insulating nature of sulfur, and fast capacity decay. To address these obstacles, we report for the first time a facile synthesis of an amorphous cobalt boride (Co₂B)@graphene material as a novel sulfur host, which provides high specific capacity and cycling performance. Endowed by the unique “synergistic effect” of Co and B interaction with polysulfides and the high electrical conductivity of graphene, the cobalt boride (Co₂B)@graphene composite shows a specific capacity of 1487 mA h g⁻¹ at 0.1C and delivers an outstanding cycling performance with a capacity of 758 mA h g⁻¹ for the 450^th cycle at 1C, representing a 0.029% fading rate per cycle.