Excimer ultraviolet-irradiated graphene separator for suppressing polysulfide shuttling in Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries are expected to become efficient new-generation energy storage systems owing to their properties such as high theoretical specific capacity (1675 mAh g−1) and high energy density (2600 Wh kg−1). However, some factors restrict their rapid development; for example, the dissolution and migration of polysulfides during the charge and discharge process, extremely poor conductivity of sulfur, and increase in volume. A glass fiber separator with graphene was loaded on a surface modified by excimer ultraviolet light (EUV/graphene separator) as the separator for Li–S batteries. The modified separator was irradiated by excimer ultraviolet light with graphene powder loaded on a glass fiber via vacuum filtration; this can effectively block polysulfide diffusion and improve the utilization rate of active materials when assembled into a Li–S battery. The first discharge specific capacity for this separator was as high as 1164 mAh g−1 at 0.2 C; after 300 cycles, the specific capacity was maintained at 640.5 mAh g−1. This modified separator guarantees the efficient migration of lithium ions and effectively inhibits the shuttle effect of Li–S batteries.