Hydrothermal synthesis of the AC@In3S4 composite and investigation of its enhanced electrocatalytic properties for improving the energy-storage efficiency in vanadium redox flow batteries and supercapacitors†

Abstract

Recent studies on redox flow batteries and supercapacitors have focused on grid-scale and micro-scale energy-storage systems, typically utilizing carbon composite materials as cost-effective electrocatalysts. Herein, we report an eco-friendly and safe method for synthesizing the AC@In₃S₄ active material, which was coated onto 132 cm² of graphite felt (MGF). This MGF acts as an electrocatalyst for VRFB applications. We observed that the MGF increased the catalytic activity toward the VO₂⁺/VO²⁺ ions, achieving a 90% Coulombic efficiency (CE) along with good cycle stability up to 100 cycles at a current density of 60 mA cm⁻². Furthermore, the AC@In₃S₄ material was also investigated for supercapacitor applications, demonstrating excellent capacitive performance in 1 M H₂SO₄. Specifically, it delivered a high C_s of 256 F g⁻¹ with a CE of 80.82% and 96.11% retention at up to 3900 cycles. This pioneering work demonstrates that AC@In₃S₄ composites possess significant potential as low-cost, environmentally friendly, and efficient materials for sustainable energy-storage applications.