Deciphering the defect micro-environment of graphene for highly efficient Li-S redox reactions

The lithium polysulfides (LiPS) dissolution into electrolyte as well as consequent shuttle behavior seriously exacerbate the electrochemical performance of lithium-sulfur batteries. Herein, the intrinsic defect of graphene has been tailored by using plasma irradiation. The topological defective carbon structure is demystified into monovacancy and divacancy which effectively promote Li-S redox kinetics by selectively decelerating the generation of soluble high-order LiPSs and passingly promoting the conversion to final solid products. Theoretical prediction uncovers the selective manipulation of Li-S redox kinetics by defective graphene, facilitating the reduced overpotential effect and uniform deposition of Li2S. Moreover, the divacancy presents a higher activity for Li-S chemistry in contrast with monovacancy. Therefore, the battery achieves superior cyclability with a capacity retention of 88.6% at 1.0 C over 300 cycles. Furthermore, it yields an areal capacity up to 8.5 mAh cm(-2) with a sulfur loading of 13.3 mg cm(-2).