N, O co-doped carbon aerogel derived from sodium alginate/melamine composite for all-solid-state supercapacitor

Hierarchical porous carbon shows great potential in the field of energy storage due to high porosity, large surface area, and excellent electrical conductivity. Here, we successfully fabricated carbon aerogel derived from sodium alginate/melamine composite (SAM) by directional freeze-drying combined with simple carbonization and activation process. The optimal SAM-700-4 possesses a high nitrogen (5.67 at.%) and oxygen (8.98 at.%) contents along with high specific surface area of 2577.62 m 2 /g and unique directional channel structure. Due to their synergistic effect, the SAM-700-4 electrode exhibits a high specific capacitance of 441.80   F/g at a current density of 0.5 A/g. Interestingly, the all-solid-state symmetric supercapacitor based on SAM-700-4//SAM-700-4 in PVA/SA/KOH gel electrolyte has a large energy density of 20.87 Wh/kg at a power density of 4000 W/kg and exhibits excellent cycling stability. It is believed that this N, O co-doped directional hierarchical porous carbon aerogel may show promising prospects as advanced energy storage materials.