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

Abstract

Abstract 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.

Keywords

• defect micro‐environment
• defective graphene
• lithium–sulfur battery
• plasma irradiation
• sulfur redox reaction kinetics