Direct insight into sulfiphilicity-lithiophilicity design of bifunctional heteroatom-doped graphene mediator toward durable Li-S batteries

Abstract The practical applications of lithium-sulfur (Li-S) battery have been greatly hindered by the severe polysulfide shuttle at the cathode and rampant lithium dendrite growth at the anode. One of the effective solutions deals with concurrent management of both electrodes. Nevertheless, this direction remains in a nascent stage due to a lack of material selection and mechanism exploration. Herein, we devise a temperature-mediated direct chemical vapor deposition strategy to realize the controllable synthesis of three-dimensional boron/nitrogen dual-doped graphene (BNG) particulated architectures, which is employed as a light-weighted and multi-functional mediator for both electrodes in Li-S batteries. Benefiting from the “sulfiphilic” and “lithiophilic” features, the BNG modified separator not only enables boosted kinetics of polysulfide transformation to mitigate the shuttle effect but also endows uniform lithium deposition to suppress the dendritic growth. Theoretical calculations in combination with electro-kinetic tests and operando Raman analysis further elucidate the favorable sulfur and lithium electrochemistry of BNG at a molecular level. This work offers direct insight into the mediator design via controllable synthesis of graphene materials to tackle the fundamental challenges of Li-S batteries.