To develop the energy density in the next stage, the same was fabricated as a asymmetric supercapacitor in which the CNT@HCNF-1.5 and Co3O4 deposited over Ni foam were employed as a negative and positive electrode, respectively. Hence the fabricated flexible asymmetric supercapacitor delivered a ultrahigh energy density of 87.5 Wh Kg -1 as well as high capacitance retention of 93.2% from its initial value after 10000 cycles. Very recently, we developed the N, P co-doped CNT via CVD with acetylene and di-ammonium hydrogen phosphate as the dopants and accomplished the enriched gravimetric capacitance of 358.2 F g - 1 at 0.5 A g -1 in 1 M H2SO4 aqueous solution . XPS analyses revealed the atomic percentage of N and P in the synthesized material are found to be 2 and 0.9 at. %, respectively.