Unlocking the Power of Woody and Non-Woody Biochar: Maximising Supercapacitor Performance Through Feedstock and Activation Treatment Selection

Abstract

This study investigates the influence of feedstocks and activation methods on the electrochemical properties of activated biochars, which are promising electrode materials for energy storage devices. Two categories of lignocellulosic biomasses (woody and non-woody) and three activation methods (CO2, steam, and KOH) were used to produce biochars, and the physicochemical and electrochemical properties were evaluated. The results showed that biochars derived from non-woody had higher specific capacitance than woody biochars, despite lower electrical conductivity and porosity. Chemical activation was found to increase volatile matter and porosity of the biochar material, resulting in improved electrochemical performance compared to physical activation. However, chemical activation can cause low electrical conductivity. KOH activated Miscanthus straw pellet biochar exhibited best specific capacitance of 468 F g-1. The study highlights the importance of carefully selecting the feedstocks and activation methods to optimise the electrochemical properties of biochar for potential commercial use as a sustainable supercapacitor material.

Keywords: Agriculture waste, Biochar, Supercapacitor, Activation, Carbon material