Fabrication of nitrogen and phosphorus-codoped porous carbon for high volumetric performance supercapacitors

• Using the MnO 2 as the self-sacrificial template and oxidant agent synthesis of nitrogen and phosphorus codoped porous carbons (NPPCs). • The fabricated NPPC-700 electrode achieves superior volumetric performance and rate retention performance. • The theoretical calculation demonstrates the N and P atoms codoping in the NPPC-700 could improve Na atom adsorption properties. • The electronic structure analysis indicates that there are ionic and partial covalent bonds co-existing during the Na atom adsorption on the doped carbon surface. Porous carbon with outstanding volumetric performance is particularly attractive and important for the miniature energy storage device in practical applications. However, the porous carbon is restricted by its large pore volume and poor density, resulting in the undesirable volumetric performance. Herein, we present a facile strategy for the fabrication of nitrogen- and phosphorus-codoped porous carbons (NPPCs) by utilizing the MnO 2 as the self-sacrificial template and oxidant agent, which display its excellent volumetric performance as supercapacitor electrode material. The NPPC-700 electrode demonstrates an outstanding volumetric capacitance of 398.11 F cm –3 at 0.5 A g –1 , and the symmetrical device delivers a volumetric energy density of 20.48 Wh L –1 at a power density of 511.0 W L –1 in Na 2 SO 4 electrolyte. The theoretical calculation also shows that the N and P atoms codoping in the NPPC-700 could enhance the Na atom adsorption properties. Furthermore, the electronic structure analysis indicates that ionic and partial covalent bonds coexist during the Na atom adsorption on the carbon surface. These results demonstrate that the NPPC-700 has considerable potential for future applications in high-performance supercapacitors.