Biomass Activated Carbon Composites and Their Potential in Supercapacitor Applications: Current Trends and Future Perspectives

Supercapacitors have attracted increasing research interest in the search for high-power and high-energy-density energy storage systems, because they combine the exceptional power density of double-layer electrodes with the high energy density of faradaic-type electrodes into a single device. Biomass has been used as a renewable precursor to prepare carbonaceous electrodes for supercapacitor application, because of its diverse compositions and morphologies, excellent intrinsic structures, and renewability. Moreover, biomass activated carbons combined with pseudocapacitive/2D materials have become more popular as high-performance electrodes for supercapacitors in recent years. Therefore, we provide an overview of recent developments in the biomass activated carbon-based composites containing metal oxides, hydroxides, sulfides, MXenes, metal–organic frameworks (MOFs), and polymers with some physical properties and their applications for supercapacitors. These electrodes offer a lot of commercial application potential, because of their remarkable electrochemical stability, excellent cyclic stability, high electrical conductivity, and effective charge transport kinetics at the electrode/electrolyte junction. In relation to the utilization of high-performance supercapacitor electrodes, we have completed this Review with some future trends and opportunities for development of composite electrodes with biomass activated carbon as the conductive template.