Preparation of nickel oxide nanoparticles/biomass-derived activated carbon composites for high-performance aqueous asymmetric supercapacitor electrode

Developing supercapacitors with higher energy density and better cycling performance at a low cost requires cost-effective advanced electrode materials with high specific capacitance and high structural sustainability. In this study, we synthesized nickel-MOF/waste sugarcane bagasse (WSB) fiber composites using a hydrothermal process and pyrolyzed them into nickel-oxide/activated carbon (NiO@AC) composites. The spectroscopic and morphological investigations confirmed that Ni-MOF has converted to NiO nanoparticles, while WSB has become highly porous carbon. The electrochemical performances of the NiO@AC composites were evaluated in a highly basic medium and investigated their suitability as electrode materials for asymmetric supercapacitor system. The NiO@AC electrode delivered a high specific capacitance of 364.13 F g- 1 at a current density of 0.2 A g- 1 , which is 3.5 times higher than that delivered by the WSB-derived activated carbon (WSB-AC) electrode. Furthermore, the NiO@AC electrode retained 95.98 % capacitance and exhibited 88.88 % coulombic efficiency after 5000 cycles. An asymmetric supercapacitor cell (ASC) was assembled using a NiO@AC electrode as an anode and a WSB-AC electrode as a cathode, and it delivered a high energy density of 44.07 Wh kg- 1 at a power density of 401.7 W kg- 1 , which is superior to several reported carbon-based ASCs. Therefore, these impressive electrochemical properties make NiO@AC composite an attractive electrode material for supercapacitors. Furthermore, the utilization of waste sugarcane bagasse as a sustainable and renewable carbon source would not only reduce material costs but also offer a solution to the problem of waste management in various sugar mills. This work can lead to manufacting innovation in the future.