Supercapacitive study of a high entropy alloy and green carbon composite electrode with a wide potential window (1.3 V) and its application towards an aqueous symmetric device

Abstract

The development of high-performance energy storage devices is essential for advancing sustainable technologies. This study explores the potential of a novel composite material composed of high entropy alloys (HEAs) and green carbon for supercapacitor applications. High entropy alloys, characterized by their unique multi-principal element compositions, offer exceptional electrochemical stability and electrical conductivity. When combined with green carbon derived from biomass, the composite exhibits synergistic effects, including enhanced capacitance, high energy density, and improved cycling stability. Accordingly, the synthesis of rice straw green carbon and its composites with high entropy alloys refers to a novel material for high-specific capacitance supercapacitor applications. The green carbon composite electrode along with Fe–Co–Ni–Cr–Mn (FCNCM) high entropy alloy powder exhibits a significantly improved specific capacitance value of 450 F g⁻¹ at 2 A g⁻¹ as compared to pure HEA and biochar electrode in a three-electrode system with a wide potential window of 1.3 V. These outstanding three electrode characteristics enabled the development of a symmetric liquid state device with a 3 M KOH aqueous electrolyte operated up to 1.8 V and displays a specific energy of 33.5 W h kg⁻¹ by consuming specific power of 1800 W kg⁻¹.