Novel Electrodeposition Method for Cu-In-Cd-Ga Sequential Separation from Waste Solar Cell: Mechanism, Application, and Environmental Impact Assessment

While CIGS solar cell has been experiencing an expanded photovoltaic market and increasing research interest in cell design, its treatment after obsoletion remains an upcoming issue. The heavy metals involved, such as Cd, can threat the environment, while strategic resources, such as rare metals In and Ga, offer a great recycling oppotunity. However, due to its multimetal feature, traditional recycling methodology shows poor separation-extraction efficiency and additional environmental burdens with intense reagent consumption and waste generation. Here, we report a sequential electrodeposition method for pure metal recycling from this Cu-In-Cd-Ga quaternary system in a more environmentally friendly and efficient manner. Stability constant-corrected redox potential supplemented with metal electroreduction tests predicts well the potential window for sequential electrodeposition. Cu and In electrodeposition shows 100% separation with high Coulombic efficiency (>80%), whereas Ga electrodeposition presents slower kinetics and performs better at a pH of 2.5. Environmental impact assessment indicates that the proposed recycling route allows remarkable reduction of global warming and toxicity impacts compared with metal production from virgin mining and reference processes. We further unveiled the applicability of the electrodeposition technique in the context of anthropogenic mineral recycling, emphasizing resource sustainability and cleaner production.