Hybrid electrolyte-mediated nano-scaled γ-Fe2O3 cathode for emerging aqueous zinc battery

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.

Unraveling chemical origins of dendrite formation in zinc-ion batteries via in situ/operando X-ray spectroscopy and imaging

To prevent zinc (Zn) dendrite formation and improve electrochemical stability, it is essential to understand Zn dendrite growth, particularly in terms of morphology and relation with the solid electrolyte interface (SEI) film. In this study, we employ in-situ scanning transmission X-ray microscopy (STXM) and spectro-ptychography to monitor the morphology evolution of Zn dendrites and to identify their chemical composition and distribution on the Zn surface during the stripping/plating progress. Our findings reveal that in 50 mM ZnSO4, the initiation of moss/whisker dendrites is chemically controlled, while their continued growth over extended cycles is kinetically governed. The presence of a dense and stable SEI film is critical for inhibiting the formation and growth of Zn dendrites. By adding 50 mM lithium chloride (LiCl) as an electrolyte additive, we successfully construct a dense and stable SEI film composed of Li2S2O7 and Li2CO3, which significantly improves cycling performance. Moreover, the symmetric cell achieves a prolonged cycle life of up to 3900 h with the incorporation of 5% 12-crown-4 additives. This work offers a strategy for in-situ observation and analysis of Zn dendrite formation mechanisms and provides an effective approach for designing high-performance Zn-ion batteries.