Owing to the superior performances of AF-PCMRST-900, a symmetrical supercapacitor was assembled in 1 M Na2SO4 aqueous solution with a high potential window of 1.8 V. The symmetric supercapacitor electrode delivered the specific capacitance of 58.5 F g -1 at 0.5 A g - 1 with a retention of 94% after 100000 charge-discharge cycles at 1 A g -1 . Further, the AF-PCMRST-900 symmetric supercapacitor displayed a higher energy density of 26. The cyclic-stability experiments were performed in a twoelectrode system using 6 M KOH at A g -1 current density, which showed the capacitance retention of 95.74% after 100000 cycles. The overall performance of the fabrication N-HNC supercapacitor electrode was determined by calculating the energy and power densities. N-HNC exhibited the energy density of 15.99 W h Kg -1 at 500 W Kg -1 , and there was no remarkable decrement in the energy density at higher power density, with the energy density still remained at 11.97 W h Kg -1 for a power density of 10 4 W Kg -1 . Further, the capacitive behaviour of the N-HNC electrode showed the electrode resistance (Rs) of 0.29 Ω, which confirmed the low internal resistance and good conductivity. Further, the phase shift of 79.2 degree, reflected the ideal EDLC behaviour of the prepared carbon materials with a low resistance.