Facile synthesis and characterization of Bi13S18I2 films as a stable supercapacitor electrode material

Abstract

Electrical double layer capacitors (EDLCs) featuring low-cost and solution-processable electrode materials have attracted significant research interest for their green and economical applications in energy harvesting and storage devices. Here, we demonstrate a novel synthetic route for films of an underexplored 3-D hexagonal bismuth chalcohalide, Bi₁₃S₁₈I₂, and investigate its potential as the active electrode material in EDLC-type supercapacitors. The synthetic procedure has been optimised and comprises the lowest annealing temperature (150 °C) and the shortest processing time (1 h) currently reported. When integrated in a symmetrical EDLC with an aqueous NaClO₄ electrolyte, the Bi₁₃S₁₈I₂-based device achieves a remarkable areal capacitance of 210.68 mF cm⁻² with 99.7% capacitance retention after 5000 cycles. Both the Bi₁₃S₁₈I₂ powder and thin-film electrodes have been characterized through XRD, XPS, Raman spectroscopy, and SEM. The superior stability, low-cost, and facile synthesis of Bi₁₃S₁₈I₂ proves its promising potential for supercapacitor applications.