Moreover, the optimised material was fabricated as flexible solid-state supercapacitor (FSSCs) exhibits an high volumetric energy density of 1.7 mWh cm -3 along with 4.6% decay after 10000 cycles demonstrating the excellent electrochemical stability of the FSSCs. investigations revealed that the Cl-doped RGO film attained a gravimetric capacitance of 210 F g -1 at 1 A g -1 which is appreciably larger than RGO film without chlorine (140. 5 F g -1 ) in 6 M KOH aqueous solution as the electrolyte and 94.3% of initial capacitance retained after 5000 cycles at 30 A g -1 . It was also demonstrated that the areal capacitance is directly proportional to the mass loading. Moreover, the Cl-doped RGO film based flexible solid-state device with the mass loading of 11 mg cm -2 achieved a very high areal capacitance as well as energy density of 2312 mF cm -2 and 160.6 μW h cm -2 in PVA-KOH gel electrolyte, respectively. Interestingly, the flexible solid-state device could drive a toy fan unceasingly even during intense bending or rolling process as displayed in Fig. . prepared the F-doped graphene aerogel by the hydrothermal treatment of GO with HF at 150 °C for 12 h and the subsequent freeze drying . The F-doped graphene aerogel with 4.5 at. % of fluorine showed an enhanced specific capacitance of 279.8 F g -1 at 0.5 A g -1 in 6 M KOH aqueous electrolyte solution which is higher than graphene aerogel without fluorine (141. 6 F g -1 ) as the SBET of former (312.6 m 2 g -1 ) is larger compared to the latter (198.6 m 2 g -1 ). Moreover, the good electrochemical stability with the capacitance retention of 94% after 5000 cycles at 0.5 A g -1 was obtained. The F-doped graphene was fabricated as a symmetric . It was observed that with increasing the concentration of ammonium chloride, the content of chlorine from XPS increases while both the SBET and the pore volume first increases and then decreases. Among the three various samples, the Cl-doped graphene prepared from the 0.02 M of NH4Cl displayed the maximum volumetric capacitance of 160 F cm -3 at 20 mV s -1 in PVA/H2SO4 gel electrolyte along with 98.1% of capacitance retained after 250000 cycles as it got the highest SBET of 238.8 m 2 g -1 as well as the largest pore volume of 0.83 cm 3 g -1 . Fig. represents the cycling stability of Cl-doped graphene derived microsupercapacitor at different current densities in three stages. Moreover, the assembled MSC flexible device exhibited the high volumetric capacitance and volumetric energy density of 160 F cm -3 and 97.9 m Wh cm -3 in EMIMBF4/PVDF-HFP along with 94.8% of capacitance retained after 10000 cycles and also powered LED with variety of colours at 3.5 V which was apparently depicted in Fig. . Yucel et al. reported the synthesis of Cl-doped RGO via electrochemical exfoliation of graphite electrodes in 5 M HClO4 solution with different potential ranges . Among the different potential ranges and the optimised cycles, the Cl1-GE40 (40 th cycle obtained at -1 to + 1.9 V), Cl2-GE20 (20 th cycle obtained at +0.8 to + 1.9 V) and Cl3-GE50 (50 th cycle obtained at 1.26 to +1.9 V) accomplished the specific areal capacitance of 248.5, 1264.8 and 2531 mF cm -2 at 10 mA cm -2 in 1 M H2SO4 solution. The remarkable increase in the capacitance of Cl3-GE50 is due to the presence of oxygen functionalities. The supercapacitive performance of halogen doped graphene reported in the different literatures is displayed in Table . 180 °C for 12 h and freeze-drying method using ammonia boron trifluoride as the source of boron . Hence all-solid-state device fabricated using PVA/H2SO4 gel electrolyte and delivered the specific capacitance of 62 F g -1 at 5 mV s -1 along with high energy density of 8.6