High‐Density Co and N Dual‐Doping in Self‐Supporting 3D Graphene Aerogel for Synergistically Enhanced Supercapacitor Performance

Graphene aerogel (GA) is characterized by its 3D interconnected conductive network, ultra‐high specific surface area, and exceptional chemical stability, and has emerged as the preferred skeleton material for supercapacitors. However, the double‐layer mechanism that exclusively relies on physical ion adsorption presents challenges in further enhancing its specific capacitance. Fortunately, cobalt (Co) exhibits multiple valence states and possesses a high theoretical specific capacitance. This characteristic not only enhances the capacity for ion adsorption on its surface but also introduces redox‐active sites, thereby significantly contributing to the achievement of high pseudocapacitance. In this study, we successfully synthesized Co/nitrogen (N) co‐doped graphene aerogel (Co‐NGA) by a one‐step hydrothermal co‐doping strategy. By leveraging the coordination capability of N atoms within the graphene lattice, the atomic‐level dispersion and stable anchoring of Co atoms were achieved. The synergistic effect resulting from the combination of a porous structure and Co/N co‐doping endows this aerogel with outstanding electrochemical performance in supercapacitor applications. At a current density of 1 A/g, the specific capacitance of 5.6%Co‐NGA achieves an impressive value of 2092 F/g, significantly surpassing that of NGA (390 F/g) and GA (239 F/g). Furthermore, an asymmetric supercapacitor assembled using 5.6%Co‐NGA and activated carbon (AC) demonstrates great energy storage capabilities. This work presents a promising strategy for designing high‐performance capacitor electrode materials and highlights the promising application prospects within the realm of supercapacitors.