Advancing Supercapacitors with Coconut Rachis Activated Carbon: A Sustainable Electrode Material

¹ Department of Physics, Amrita Vishwa Vidyapeetham, Amritapuri, Kollam, 690525, Kerala, India;
² Center for Advanced Intelligent Materials & Universiti Malaysia Pahang, 26300 Kuantan, Pahang, Malaysia
³ Faculty of Industrial Sciences and Technology, Universiti Malaysia Pahang, 26300 Kuantan, Pahang, Malaysia

Abstract

Carbon derived from renewable energy sources plays a crucial role in fostering sustainability within supercapacitor applications. This study investigates the use of activated carbon produced from a unique biomass source, coconut rachis, containing approximately 81% carbon, as a potential electrode material. The coconut rachis-derived activated carbon features a high surface area (around 1630 m²·g⁻¹) and a honeycomb-like surface structure, which enhance its ability to adsorb electrolyte ions efficiently. This carbon is termed as honeycomb-shaped porous carbon (HSPC). The performances of these electrodes in adsorbing different cations, i.e., Na⁺ and Li ⁺ in 1M Na₂SO₄ and 1M Li₂SO₄ electrolytes, were studied and reported a higher specific capacitance. The supercapacitor performance using 1M Na₂SO₄ as an electrolyte shows a high energy density and potential window. The supercapacitor also shows excellent cyclic stability with an increment in capacitance retention from 82 % to 93% over 2000 cycles. Keywords: Renewable carbon, Bioresources, Electrochemical Double Layer Capacitor (EDLC), Cation adsorption, Supercapacitors.