Stabilizing interface of novel 3D-hierarchical porous carbon for high-performance lithium–sulfur batteries

Abstract

Li–S batteries (LSBs) are promising next-generation rechargeable batteries owing to their high theoretical capacity (1675 mAh g − 1), high energy density (2500 Wh kg−1), and affordability. However, the practical application of LSBs is hindered by rapid capacity fading and poor cycle life due to the shuttle effect of dissolved polysulfides. In this study, 3D-hierarchical porous carbon impregnated with sulfur (S@3DC), followed by coating with polyvinylpyrrolidone (PVP), is used as a cathode for LSB. The 3D-hierarchical carbon possesses high porosity with micro/mesopores and an open framework that enables the electrolyte penetration for fast ion/mass transfer. The Li–S cells employing PVP-coated S@3DC cathode depicts excellent cycling stability with a high initial capacity of ∼1527 mAh g − 1 at 0.1 C, capacity retention of 80.66% after 800 cycles at 1.5 C, and a remarkable rate capability up to a high rate of 2 C. The thin PVP layer coating, used as a buffer layer on the S@3DC surface, contributes appropriate functional groups at the sulfur-carbon interface. These functional groups enhance sulfur immobilization and suppress the shuttle effect; they also provide additional electrochemically active sites on S@3DC surface for accelerating the charge transfer kinetics between electrode and electrolytes.