Transformative Hydrochloric Acid Treatment of Red Mud for Sustainable Cathode Material Production in Aqueous Zinc Ion Batteries

Abstract

The aluminum industry generates a significant amount of red mud as solid waste. This waste is high in mineral content, particularly metal oxides, and difficult to treat, manage, and recycle, resulting in malignant environmental effects. A simple, scalable, and precisely controlled hydrochloric acid treatment transforms the red mud into a useful product by selectively removing electrochemically inactive phases. This process produces a highly porous material with a significantly increased surface area, which effectively serves as the cathode material in an aqueous zinc ion battery (AZIB). RM‐HCl, which was treated with acid, had better electrochemical performance than plain red mud (RM). It had an initial specific discharge capacity of 105 mAh g‐1 at 0.2 to 1.8 voltage and a current density of 100 mA g‐1, which stayed at 63% after 250 cycles. It also showed long‐term cyclic stability at high currents of 500 mAg‐1 and 1000 mAg‐1 for 1000 cycles. The properties of a cathode material made from RM have the potential to be a cost‐effective and environmentally friendly option. This study proposes a practical, sustainable, and expandable technique for recycling RM that promotes eco‐friendly and sustainable growth in the aluminium industry.