Hence the assembled solid-state symmetric supercapacitor delivered an energy density of 24.7 Wh Kg -1 at 1 A g -1 in PVA-KOH gel electrolyte. It has been suggested that the heteroatoms significantly promote the reversible redox reactions with the help of their unshared pair of electrons thereby improving the pseudocapacitance. Chen et al. investigated the electrochemical capacitive performance of N, S co-doped porous graphene hydrogel which was obtained by the hydrothermal treatment of GO and hydrazine hydrate with sulphur in different mass ratios in autoclave at 200 °C for . The elemental composition of the optimized material from XPS revealed that it possesses the 5.24 at. % and 0.52 at. % of nitrogen and sulphur, respectively. The sample prepared in this report was fabricated as a symmetric supercapacitor and achieved the specific capacitance of 203 F g -1 at 1 A g -1 in EMIMBF4 solution and the outstanding energy density of 100 W h kg -1 was obtained at a power density of 0.94 kW kg -1 and the excellent capacitance is owing to the fact that it has got the maximum SBET of 242.3 m 2 g -1 . Zhang et al. prepared the N, S co-doped graphene by hydrothermal at 180 °C for 24 h using ammonia and thiourea as the precursors . Thus, the synthesized material has got the specific capacitance of 1063 C g -1 at 1 A g -1 in 6 M KOH aqueous solution and 76% of the original capacity retained after 6000 cycles. Besides, all-symmetric solid-state supercapacitor was fabricated in the absence of any binders and delivered an energy density of 6.25 Wh kg -1 at a power density of 500 W kg -1 . The appreciable increment in the supercapacitive performance is accounted to various factors such as high surface area, porous nature and the pseudocapacitive nature due to the presence of heteroatom active sites such as nitrogen and sulphur. Lu et al. produced the N, S co-doped graphene aerogels by subjecting the mixture of GO and 2-mercapto-1-methyl-imidazole in different weight proportions to hydrothermal at 200 °C for 12 h followed by the freeze-drying . Out of samples having the variety of proportions, the material derived from the mass ratio of dopant and GO is 2 (N/S-GA-2) was constructed as a symmetric supercapacitor and produced a maximum specific capacitance of 212 F g -1 along with ultra-high energy density of 117 W h kg -1 at power density of 1.0 kW kg -1 at 1 A g -1 at 1 A g -1 in EMIMBF4 as the ionic liquid electrolyte where the operating voltage reached 4 V. XPS characterizations revealed that the atomic percentage of N and S present in the N/S-GA-2 are calculated to be about 2.77 and 0.89 %, respectively.