Also, the device displayed an excellent cyclic stability over 5000 cycles with retention in capacitance of 90.8%. Besides, another single asymmetric device fabricated using CuBG and activated carbon as the positive and negative electrode in PVA/KOH as the solid electrolyte, respectively. This device delivered a high energy density of 31.1 W h kg -1 at a power density of 800 W kg -1 in the cell voltage of 1.6 V with good electrochemical stability showing the 84.5% retention in capacitance from its initial value along with 93% coulombic efficiency. In studies indicated that the specific capacitance of SmMO-NPRGO hybrid was found to be 668 F g -1 which is appreciably higher than SmMO (400 F g -1 ) and SmMO-RGO (516 F g -1 ) at 0.5