Recent advances of chitosan-based nanocomposites for supercapacitor applications: Key challenges and future research directions

The scientific community must follow renewable and sustainable energy sources because of the remarkable decline in fossil fuels and the simultaneous rise in energy demand. A key issue limiting the variety of energy that can be used from these sources is the lack of effective energy storage devices (ESDs). Hence, researchers' interest has recently been drawn to supercapacitors (SCs) as a developing class of ESDs because of their exceptional cycle life, high power density, and ability to charge quickly without experiencing thermal runaway or explosion. Nowadays, the electrodes used in SCs are created using environmentally hazardous, carcinogenic, and nonrenewable materials. Biopolymers are a promising replacement for these materials. Recently, chitosan (CS) has been extensively utilized for use in supercapacitors among the polysaccharides examined in creating nanocomposites (NCs) (either pure or coupled with natural or synthetic polymers). This review focuses on the recent five years' advancements in CS-based nanocomposites (CS-NCs), their properties, and notable discoveries in the field of supercapacitors in light of the future potential uses for such materials. Also, the performance of chitosan-based electrodes is compared with the currently used electrodes for supercapacitor applications. Finally, the challenges and possible directions for future studies are also mentioned.