Modification techniques to improve the capacitive performance of biocarbon materials

Carbon materials that are derived from various biomasses receive increasing importance in energy storage and conversion applications, especially in supercapacitors due to their physicochemical, structural and morphological features. Advantages of biocarbon materials as supercapacitor electrode are their abundance, structural and morphological diversity, renewable origin and eco-friendly feedstock. However, they exhibit limited capacitive performance as its pristine form due to lower porosity that reflects on their active surface area, limited electrical conductivity and poor structural stability over the larger cycling activity. In order to overcome these challenges, various physicochemical modification techniques have been adopted for the biocarbon materials, which include activation, surface modification, metal/ metal oxide incorporation and composite fabrication. As there is an exponential demand in utilizing sustainable materials for high-performance supercapacitor, this review summarizes the recent developments on the various modification techniques that deal with the biomass-derived carbon materials for supercapacitor applications.