Chitosan-based materials for supercapacitor applications: a review

Increasing demand of energy with an exponential depletion of fossil fuel has persuaded the scientific community to search for renewable and sustainable sources of energy. Lack of efficient energy storage devices (ESD) is one of the great challenges that ultimately diminish the diverse applications of energy from these sources. Supercapacitor, an emerging ESD, has drawn the special interest of researchers due to its outstanding cycle life, high power density, and ultrafast charging ability without any risk of explosion and thermal runway. Currently, electrodes and electrolytes of supercapacitors are being made of non-renewable, toxic, and hazardous materials, which are also harmful to the environment. Biopolymers can be a suitable alternative for replacing these substances. Recently, chitosan, an abundantly available biopolymer, has been exploited to develop various electrolytes and electrodes, which have exhibited promising results. Moreover, low cost, biodegradability, and environmentally safe nature of these materials have drawn a lot of interest for further research and investigation, which has led to the publication of increased number of papers every year. This review has summarized and critically analyzed the recent developments of various chitosan-based electrodes and electrolyte materials for supercapacitor applications. Further, the performance of these supercapacitors is evaluated and compared with currently available highly efficient materials. Finally, the remaining challenges and possible future research directions are also outlined.