Advances in electrochemical recovery of valuable metals: A focus on lithium

Lithium demand has been increasing greatly due to its primary importance in energy storage systems. This has exposed critical limitations in traditional extraction processes such as solar evaporation and hard rock mining. These methods usually suffer from long processing times, low lithium selectivity, extensive land use, and are environmentally disruptive. As a result, there is a growing need for cleaner, more selective alternatives. Recovery from different sources such as salt lake brines, seawater, geothermal brines, and battery recycling streams has brought the exploration and development of novel recovery technologies. Electrochemical techniques are usually more compact and present a lower by-product waste disposal burden than conventional methods, including hard rock mining, solar evaporation, etc. This in turn, helps in minimizing the landscape disruption and lowering the ecological footprint of lithium extraction operations. Another important advantage of electrochemical methods is that they do not usually employ chemicals that would result in soil and groundwater pollution; thus, they are much cleaner processes. In this work, the recent advances in the electrochemical recovery of valuable metals are summarized with special emphasis on lithium recovery from various sources using processes such as capacitive deionization (CDI) and electrodialysis (ED), all carrying efficiency and selectivity, with less impact on the environment. Furthermore, this review aims to offer a basic understanding of electrochemical processes and compile their contributions toward environmental impact reduction while highlighting their viability alongside green extraction paradigms that tackle, in context, the reduction of the dependence on traditional high-impact mining processes. Additionally, hybrid electrochemical processes such as coupling CDI with a fractional submerged membrane distillation crystallizer (F-SMDC), and the integration of F-SMDC with electrocrystallization are suggested to improve the lithium extraction performance of electrochemical methods.