Waste to Energy Storage: Fe‐Doped ZnO /Carbon Anodes Synthesized From Galvanizing Flue Dust

ABSTRACT Zinc, in a complex form, is one of the main components of the flue dust formed during the hot‐dip galvanizing (HDG). Its disposal not only causes economic losses but also poses significant environmental challenges. In alignment with circular economy, the utilization of such industrial residues in value‐added applications becomes vital. Herein, using HDG flue dust as an input material, a novel approach for synthesizing Fe‐doped ZnO/carbon‐based composite anode materials for lithium‐ion batteries (LIBs) is proposed. In this scope, a three‐step process comprising neutral leaching, calcination, and ball milling is employed for the fabrication. Neutral leaching is optimized to enrich the hot‐dip galvanizing (HDG) flue dust residue with zinc and iron while simultaneously reducing the concentrations of ammonia and chlorine. The optimal leaching conditions (95.7 wt% Zn retention efficiency) are determined to be 80°C, a solid to liquid ratio of 1:100, and a leaching time of 1 h at 750 rpm. Later, the solid residue is subjected to thermal treatment at 500°C for 4 h, resulting in Fe‐doped ZnO powder. Lastly, the synthesized Fe‐doped ZnO powder is mechanically ball‐milled with activated carbon (AC) at three different weight ratios: Fe‐ZnO:C = 1:1, 2:1, and 3:1. Fe‐ZnO:C = 3:1 achieves the highest capacity and the best retention: at the 1st and 100th cycles, it delivers 1760.72 and 592.68 mAh g ⁻¹ , respectively. The enhanced performance of the composite is attributed to its unique properties in morphology, structure, and chemistry. image