All‐Graphene Quantum Dot‐Derived Battery: Regulating Redox Activity Through Localized Subdomains

Abstract In the quest for materials sustainability for grid‐scale applications, graphene quantum dot (GQD), prepared via eco‐efficient processes, is one of the promising graphitic‐organic matters that have the potential to provide greener solutions for replacing metal‐based battery electrodes. However, the utilization of GQDs as electroactive materials has been limited; their redox behaviors associated with the electronic bandgap property from the sp² carbon subdomains, surrounded by functional groups, are yet to be understood. Here, the experimental realization of a subdomained GQD‐based anode with stable cyclability over 1000 cycles, combined with theoretical calculations, enables a better understanding of the decisive impact of controlled redox site distributions on battery performance. The GQDs are further employed in cathode as a platform for full utilization of inherent electrochemical activity of bio‐inspired redox‐active organic motifs, phenoxazine. Using the GQD‐derived anode and cathode, an all‐GQD battery achieves a high energy density of 290 Wh kg_cathode⁻¹ (160 Wh kg_{cathode+anode}⁻¹), demonstrating an effective way to improve reaction reversibility and energy density of sustainable, metal‐free batteries.