Layer-Structured Copper Antimony Chalcogenides (CuSbSe_<i>x</i>S_2–<i>x</i>): Stable Electrode Materials for Supercapacitors

Abstract

The ever-growing need for energy generation and storage applications demands development of materials with high performance and long-term stability. A sizable number of chalcogenide-based materials have been investigated for supercapacitor applications. Layer-structured chalcogenides are advantageous in terms of providing large surface area with good ionic conductivity and ability to host a variety of atoms or ions between the layers. CuSbS₂ is a ternary layered chalcogenide material that is composed of earth abundant and less-toxic elements. For the first time, we have developed a simple colloidal method for the synthesis of CuSbSe_<i>x</i>S_2–<i>x</i> mesocrystals over the whole composition range (0 ≤ <i>x</i> ≤ 2) by substitution of S with Se. Our approach yields mesocrystals with belt-like morphology for all the compositions. X-ray diffraction results show that substitution of sulfur with selenium in CuSbS₂ enables tuning the width of the interlayer gap between the layers. To investigate the suitability of CuSbSe_<i>x</i>S_2–<i>x</i> mesocrystals for supercapacitor applications, we have carried out electrochemical measurements by cyclic voltammetry and galvanostatic charge–discharge measurements in 3 M KOH, NaOH and LiOH electrolytes. Our investigations reveal that the mesocrystals exhibit promising specific capacitance values with excellent cyclic stability. The unique properties of CuSbSe_<i>x</i>S_2–<i>x</i> mesocrystals make them attractive both for solar energy conversion and energy storage applications