Nature-inspired composite consisting of activated carbon derived from date palm kernel and poly(aniline-co-pyrrole) copolymer as electrode for energy storage devices

Addressing global environmental challenges and transitioning towards sustainable energy requires the development of advanced and low-cost energy storage materials. This study presents a novel approach for fabricating an electrode composite made from activated carbon based on date palm kernel (ACP) and a polyaniline-co-pyrrole (PANI-co-Ppy) copolymer using date palm kernel biomass waste. The porous carbon was obtained by carbonization and thermal activation and served as a substrate for the copolymer, synthesized through oxidative polymerization. ACP@PANI-co-Ppy composites were prepared at two aniline:pyrrole molar ratios of 1:1 and 1:3 and subsequently characterized through various structural and morphological analyses. Electrochemical performance was assessed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in a 3 M KOH electrolyte. ACP@PANI-co-Ppy (1:3) composite exhibited the highest specific capacitance of 65.03 F g⁻1 at 50 mV s⁻1, along with an energy density of 6.7 Wh kg⁻1, power density of 312.2 W kg⁻1, and outstanding cycling stability with 99.5% retention after 2000 cycles. Additional tests in a two-electrode system using a Na₂SO₄:H₂SO₄ (1 M, 1:1 volume ratio (v/v)) electrolyte showed a specific capacitance of 0.84 F g⁻1, energy density of 0.11 Wh kg⁻1, and power density of 100 W kg⁻1. Although performance was lower compared to the three-electrode setup, the results still confirmed its potential for supercapacitor applications. This study demonstrates an environmentally friendly and cost-effective strategy for transforming agricultural waste into high-performance materials, offering a promising path toward sustainable supercapacitor development. The ACP matrix acts as a mechanical buffer, effectively accommodating the volumetric strain of the copolymer during doping/de-doping processes, which is the key technical novelty of this work.