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

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 aluminum industry.