Performance boost for primary magnesium cells using iron complexing agents as electrolyte additives

Aqueous Mg battery technology holds significant appeal, owing to the availability of raw materials, high power densities and the possibility of fast mechanical recharge. However, Mg batteries have so far been prone to decreased capacity due to self-corrosion of the anodes from the electrochemical redeposition of impurities, such as Fe, which results in parasitic cathodically active sites on the discharging anode. This work demonstrates that by adding Fe³⁺-complexing agents like Tiron or salicylate to the aqueous electrolyte of an Mg battery, it was possible to prevent the redeposition of Fe impurities and subsequent self-corrosion of the anode surface, thereby boosting battery performance. To prevent detrimental fouling of anode surface by Mg(OH)₂, employed Fe³⁺-complexing agents must also form soluble complexes with Mg²⁺ of moderate stability. The interplay of these requirements predetermines the improvement of operating voltage and utilization efficiency.