Graphene and Polyethyleneimine Bilayer Wrapping onto Quinone Molecular Crystal Cathode Materials for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries are promising large-scale stationary batteries, owing to their safety and environmental friendliness. For cathode materials, the utilization of redox-active organic materials instead of conventional transition metal oxides is considered to be an effective approach to enhance specific capacity and eliminate resource constraints. However, the poor cyclability of these materials due to their poor electrical conductivity and high solubility hinders their practical application, calling for in-depth investigations to overcome these limitations. Herein, we demonstrate a facile graphene wrapping method for organic quinone materials. We resolve the strong Coulombic repulsion between graphene and quinone by using polyethyleneimine as an interlayer. The graphene- and polyethyleneimine-wrapped quinone exhibits superior cyclability in aqueous zinc-ion batteries by suppressing elution into the electrolyte and crystal growth of quinone during charge/discharge cycles. This bilayer wrapping concept can be widely applied to various organic materials to achieve an electrical conductivity and cyclability with high capacity.