Sulfur and nitrogen enriched graphene foam scaffolds for aqueous rechargeable zinc-iodine battery

Aqueous rechargeable zinc-based batteries are attractive as promising candidates for practical electric vehicles. However, such batteries still suffer from the poor cycling stability and potential safety issue due to the dendrite formation. Herein, we design three-dimensional (3D) graphene foams co-doped with sulfur and nitrogen via an in-situ reduction of graphene oxide and subsequent thermal annealing process. Performed as both cathodic and anodic matrixes, the unique features of 3D porous graphene framework with N, S co-doping not only enable the reversible plating/striping process of zinc, but also facilitate the redox reactions of iodine species. Thus, the rationally designed aqueous rechargeable zinc-iodine system can integrate the redox reactions of zinc and iodine redox couple at the interface of graphene foam and electrolytes along with reversible ion shuttles (e.g., Zn2+, I−/I3−) for efficient energy storage. More importantly, the 3D porous architecture with N, S co-doping can enhance the battery Coulombic efficiency by shortening the potential gap of charging/discharging process and suppress the formation of zinc dendrites by improve the reaction kinetics of reversible redox reactions.