Superior electrochemical performances of highly porous bismuth oxyhalide/lemon peel derived activated carbon electrode materials for solid state asymmetric and symmetric supercapattery devices

Abstract

The escalating global energy consumption, driven by dwindling fossil fuel reserves and rapid industrial expansion, necessitates the urgent development of alternative renewable energy solutions. Within this context, hybrid electrochemical energy storage (EES) systems, particularly the supercapattery, have emerged as a highly promising technology. This device amalgamates the high energy density of batteries with the superior power density and longevity of supercapacitors. This study investigates the electrochemical characteristics of bismuth oxyhalide (BiOX, where X = Br, Cl, I) nanocomposites with lemon peel-derived activated carbon (LPAC)—designated as BBAC, BCAC, and BIAC—for application in solid-state supercapatteries. These composites were synthesized via a straightforward ultrasonication technique. Comprehensive structural, vibrational, morphological, and elemental analyses confirm the successful anchoring of phase-pure BiOX nanostructures onto the LPAC matrix. The resultant materials exhibit a highly porous, sheet-like morphology, which facilitates enhanced electrolyte ion accessibility and charge transfer kinetics. Electrochemically, the BBAC, BCAC, and BIAC electrodes demonstrated exceptional specific capacities of 1575.15 C g⁻¹, 1228 C g⁻¹, and 905.37 C g⁻¹, respectively, at a current density of 1 A g⁻¹, significantly surpassing the capacities of the pristine components. This performance enhancement is attributed to a synergistic charge storage mechanism, combining the battery-type faradaic reactions of BiOX with the capacitive, double-layer behavior of LPAC. A fabricated symmetric solid-state supercapattery (SSC) with a BBAC‖BBAC configuration delivered a remarkable energy density of 172.06 Wh kg⁻¹, vastly outperforming its asymmetric BBAC‖LPAC (ASC) counterpart (47.1 Wh kg⁻¹). In practical demonstrations, the SSC device powered a 2 V red LED for 555 seconds and a 3.7 V electric motor fan for 122 seconds, markedly outperforming the ASC device. These findings collectively establish the BBAC nanocomposite as a premier electrode candidate for high-performance, symmetric solid-state supercapattery devices.