Synergetic Functionalization of the ZnS@ASCs Biocomposite: For Enhanced Electrochemical Performance of Redox Flow Batteries and Supercapacitors

Abstract

Redox flow batteries and supercapacitors are attracting significant attention worldwide because of their roles in grid-level energy storage and smaller-scale applications. Both of these technologies play unique roles in the operation of electrochemical energy storage devices. An investigation of ZnS@ASCs composite materials shows their excellent electrochemical performance. The cost-effective, efficient, and straightforward synthesis of ZnS and their composites with bioactivated carbon was performed using a hydrothermal technique. In the context of redox flow batteries (RFBs), the ZnS@ASCs composite material was utilized as a positive electrode with an area of 132 cm2. It acted as an electrocatalyst for both vanadium redox flow batteries (VRFBs) and iron redox flow batteries (IRFBs). The stability of the ZnS@ASC-treated graphite felt electrode was demonstrated up to 200 cycles for VRFBs and 25 cycles for IRFBs, resulting in satisfactory Coulombic efficiencies (CEs) of 86.66% and 89.26% for VRFB and IRFB, respectively. Furthermore, the ZnS@ASCs composite material is applied as a coating onto a Toray carbon sheet and is utilized as the active electrode for supercapacitor applications. This working electrode exhibited a significantly high specific capacitance of 1070.80 F/g at 4 mA/g in a sulfuric acid (H2SO4) solution. The electrode maintained impressive CEs of 97.41% and 95.87% of its initial performance after undergoing 3500 charge–discharge cycles. Notably, the ZnS@ASCs composite material has been shown to be an efficient and exceptional electrochemically active material for various energy storage devices.