The NLPC-600, NLPC-800, and PC-700 showed the capacitance of 207, 345, and 111 F g -1 , respectively. The capacitance value is found to be decreased with increasing pyrolysis temperature to 800 ˚C, due to the collapse of pore structure. Further, a symmetrical supercapacitor was fabricated using NLPC-700, which showed the excellent cycle life 99.1% specific capacitance with the energy density of 13 W h Kg -1 , and a power density of 350 W Kg -1 . The high doping amount of N, porous nature of the material, and the combined activation of Mn (CH3COO)2, KCl and CO(NH2)2 is reported to be beneficial for the improved %, respectively. In a three-electrode system using 6 M KOH electrolyte, the HPC electrode delivered the maximum capacitance of 330 F g -1 at 1 A g -1 . A symmetric two-electrode devices were assembled using 6 M KOH and 1 M Na2SO4 electrolytes, which delivered an energy storage as high as 10.93 W h Kg -1 at 100 W h Kg -1 , and 24.9 W h Kg -1 at 180 W Kg -1 , for KOH and Na2SO4 loaded device, respectively. Further, symmetric supercapacitor was constructed using lithium bis(tri-fluoromethane sulfonyl) imide (Li-TFSI) water-in-salt (WIS) electrolyte, and obtained the high energy density of 32.9 W h Kg -1 and power output of 575 W Kg utilized to characterize the intrinsic electrochemical properties of the fabricated electrode, in three-and two-electrode system, respectively. The SBET of the raw needle-coke was found to be 3.0 m 2 g -1 , however a drastic enlargement in the SBET was observed after KOH activation.