Advancements in Sustainable Electrolytic Manganese Recovery: Techniques, Mechanisms, and Future Trends

Electrolytic manganese metal (EMM) produced from recyclable resources has recently gained increasing attention due to the scarcity of high-quality manganese natural resources and its broad range of applications. This review has summarised recent progress in manganese recovery techniques, including pyrometallurgy and hydrometallurgy. It has also critically assessed the processes and mechanisms involved in manganese electrodeposition for the Mn chloride- and Mn sulphate-based systems, with a major focus on electrode reactions and Mn nucleation growth. The key optimisation factors influencing manganese electrodeposition, such as electrolytes, power consumption, additives, cell structures, and electrode materials, were analysed, with particular attention to their impact on current efficiency, specific energy consumption, and product quality. The recent research directions were also highlighted to address practical challenges and enhance the sustainability of the EMM process, which mainly includes improving the ecological outcomes and reducing both the operating and investment costs. Promising strategies for the simultaneous production of EMM and electrolytic manganese dioxide (EMD) were also identified, which mainly comprised applying membrane technology, electrodeposition from ionic liquids, recycling and reusing waste materials, and exploring hybrid techniques. The results of this study showed that the prospective optimisation approaches for EMM are mainly driven by the need to enhance efficiency, reduce costs, and improve product quality through sustainable technological advancements. This review can be used as a comprehensive guide for manganese electrodeposition approaches for both practical and scientific research communities.