Streamlined electrochemical harvesting of cobalt and nickel from soft cemented carbide scrap for superior supercapacitors

We propose a complete circular economy and sustainability model from soft cemented carbide scrap to supercapacitor application. An enhanced recovery of cobalt and nickel was observed when deep eutectic solvent was used. A comparative in-situ electrochemical deposition of the recovered metals was done on stainless steel (SS), SS/activated carbon (AC), and SS/AC/polyaniline (PANI). The optimization of electrochemical extraction was carried out by varying voltage, time, and temperature. The surface area and conductive polymer's electronic distribution contributed to different surface morphological deposition of specific metals on them. Unique fluffy particle deposition was observed on the surface as fine grain particles with uniform particle size within 1 µm. The fabricated supercapacitors showed the pseudocapacitance behaviour. The presence of metal oxide nanocomposite deposition as the active material is particularly pronounced in the SS/AC/PANI device due to the inclusion of PANI as an active material and its substantial contribution to pseudocapacitance. The higher charge-discharge time of SS/AC/PANI at the same current densities compared to SS/AC may be due to the above-mentioned additional contribution of PANI's quickly reversible redox behavior.