The JS-CK2NS electrode delivered a specific capacitance of 262.43 F g -1 at 1 A g -1 , and a superior cycling stability with 96.28% capacitance retention after 10000 cycles under 10 A g - 1 , which is higher than that of JS-C (136.08 F g -1 ), JS-CK (197. 95 F g -1 ), and JS-CKNS (232.21 respectively. The decreased SBET of ACt may be due to the acid treatment, which could cause partial destruction of the porous structure and blockage of the pore opening. The doping of phosphorous has increased the total SBET, and created more mesopores, which were blocked during the acid treatment, and it is the reason for highest SBET of ACtP-850. The XPS studies showed the presence of phosphorus-doping in the porous carbon structure. The electrochemical analysis was performed in 1 M Na2SO4 electrolyte, and the ACtP-850 electrode showed the maximum specific capacitance of 328 F g -1 at 0.5 A g -1 . Further, a symmetric supercapacitor device was fabricated using ACtP-850 electrode, and it delivered a specific energy of 29 W h