Nanostructured Activated Biomass Carbon-Cu2ZnSnS4 Kesterite Material for High-Performance Supercapacitor

Abstract

This work introduces a novel Cu2ZnSnS4 (copper zinc tin sulfide [CZTS]) kesterite/coconut shell-derived biomass activated carbon (AC) nanocomposite material (CZTS0.5:AC0.5) for supercapacitor application. CZTS was prepared by microwave-assisted synthesis and combined with AC to produce CZTS0.5:AC0.5 through mechanical milling and low-temperature annealing at 350°C. X-ray diffraction (XRD) and Raman spectroscopic analyses of CZTS0.5:AC0.5 nanocomposite revealed the formation of a multiphase system consisting of residual CZTS and secondary sulfides (zinc sulfide [ZnS], CuS, and SnS), which are embedded within a highly conductive amorphous carbon matrix. High-resolution transmission electron microscopy (HRTEM) results indicate a reduction of the particle size from 55.7 nm (for CZTS) to 21.7 nm (for CZTS0.5:AC0.5) due to annealing. The nanostructurization of CZTS0.5:AC0.5 created abundant electroactive sites that made the material an efficient charge storage system. Galvanostatic studies of AC//CZTS0.5:AC0.5 in a three-electrode configuration produced a specific capacitance (Csp) of 458.2 Fg−1 at 1 Ag−1. Two-electrode AC//CZTS0.5:AC0.5 asymmetric supercapacitor device had a maximum energy density of 12.8 Wh kg−1 and a maximum power density of 890.5 W kg−1. The supercapacitor device exhibited excellent stability with a coulombic efficiency retention of 99.99% and a capacitance retention of 81.4% after 10,000 cycles. The results portray CZTS0.5:AC0.5 nanocomposite material as a promising, sustainable electrode material for next-generation supercapacitors.