The excellent capacitive capability for N,P-doped carbon microsphere/reduced graphene oxide nanocomposites in H2SO4/KI redox electrolyte.

In order to ameliorate the capacitance and energy density of supercapacitors in aqueous electrolytes, nitrogen- and phosphorus-codoped carbon microspheres/reduced graphene oxide nanocomposites are obtained by hydrothermal treatment of graphite oxide and N,P-doped carbon microsphere. The as-prepared nanocomposites display a high specific surface area of 604.3 m2 g−1 and hierarchical pore structure composed of micropores, mesopores, and macropores. N,P-codoped carbon microspheres/reduced graphene oxide are used as electrode materials in the redox electrolyte of H2SO4 and KI aqueous solution, exhibiting a excellent capacitance performance of up to ~ 654 F g−1 at 2 A g−1, corresponding to the energy density of 14.53 Wh kg−1 at power density of 402 W kg−1. Even at a high current of 20 A g−1, the electrode can keep a capacitance of 318 F g−1, showing an energy density of 7 Wh kg−1 at power density of 3984 W kg−1. This study indicates the potential of nitrogen- and phosphorus-codoped carbon microspheres/reduced graphene oxide in high energy density supercapacitor. [ABSTRACT FROM AUTHOR]