LAUSR

Nitrogen-doped activated carbon (PNAC) have been successfully synthesized using carbonized polyvinylidene fluoride as carbon precursor via HNO3-activation and subsequent urea-assisted hydrothermal nitrogen-doping method. As a result, the PNAC electrode exhibits high specific capacitance of 247 F g−1 at 0.5 A g−1 and excellent rate performance in 2 M KOH aqueous electrolyte. Furthermore, the all-solid-state asymmetric supercapacitor (ASC) was assembled using PNAC as negative electrode, ZnCo2O4 nanosheet arrays as positive electrode and the PVA–KOH gel as solid-state electrolyte, which shows superior electrochemical behavior an energy density of 14.1 W h kg−1 at power density of 375 W kg−1 and super cycle performance of 81.3% capacitance retention after 5000 cycles at 4 A g−1. A red light-emitting-diode can be lighted using two ASC in series, demonstrating its practical potential in supercapacitors.