Interconnected N/P co-doped carbon nanocage as high capacitance electrode material for energy storage devices

Heteroatom doping carbon materials exhibit a huge application potential for energy storage devices (ESDs). Herein, interconnected N/P co-doped carbon nanocage (NP-CNC) was synthesized from pyrene molecules by using nano-MgO as template and melamine-phytic acid supramolecular aggregate as dopant coupled with KOH activation. The as-prepared NP-CNC possesses interconnected nanocages for electron transportation and abundant micropores for ion adsorption. Moreover, codoped N/P species in NP-CNC provide active sites and additional pseudocapacitance. Consequently, NP-CNC as electrode material for symmetric supercapacitor exhibits a high gravimetric capacitance of 435 F.g(-1) at 0.05 A.g(-1), high volumetric capacitance of 274 F.cm(-3) at 0.032 A.cm(-3), and long cycle lifespan with 96.1% capacitance retention after 50,000 cycles. Furthermore, NP-CNC as cathode for zinc-ion hybrid supercapacitor delivers satisfactory energy and power densities of 130.6 Wh.kg(-1) (82.3 Wh.L-1) and 14.4 kW.kg(-1) (9.1 kW.L-1). This work paves a promising approach to the preparation of high capacitance NP-CNC for ESDs.