Valorization of tar-modified rice husk activated carbon for high-performance supercapacitor electrodes

Abstract

Biomass valorization for energy storage remains limited by underutilized byproducts such as tar, generated during thermal conversion. This work demonstrates a novel approach that integrates tar as a carbon-rich modifier to engineer the pore structure and electrochemical performance of rice husk-derived activated carbon (RHAC). Rice husk was gasified to produce tar and char, with the char chemically activated using K2CO3. Different tar concentrations were mixed with the activated carbon and further activated at varied pyrolysis temperatures. Tar modification induced structural disorder and localized graphitic domains, which enhanced electrical conductivity, ion transport, and double-layer formation. The optimum material, containing 10 wt% tar and activated at 800 °C (RHACT-10), achieved a high specific surface area (1650 m2 g−1) and specific capacitance (235.6 F g−1 at 5 mV s−1), while retaining 99 % of its capacitance over 500 cycles. This study offers a new valorization route for biomass byproducts, enabling the design of hierarchical porous carbon electrodes for high-performance supercapacitors. The integration of waste-derived carbon sources into advanced energy storage materials provides a sustainable and cost-effective pathway for clean energy applications.