Electrochemical Separation and Clean Energy Applications of Rare Earth Elements

来源：ACS Publications

Rare-earth elements (REEs) are critical to multiple areas in clean energy technology, including magnets, catalysts, as well as lighting and electronic products. With the growing awareness for sustainable mining and recycling, electrochemical approaches have emerged as a promising pathway for the energy-efficient and green recovery of rare-earth elements, including processes for extraction, concentration, purification, and utilization. In this paper, we review electrochemical pathways for the recovery of REEs from mining and unconventional feedstocks, including coal mining byproducts. Electrochemical separations offer a modular alternative to the traditional thermal and solvent-based extraction methods, by potentially combining both selectivity and a low chemical footprint. We review advances in various electrolysis and electrosorption-based separation processes for REE recovery and purification, and discuss opportunities for future materials development. Finally, we provide an overview of applications of REEs in clean energy conversion, especially their use as next-generation electrocatalysts. We conclude that electrochemical processes can play an important role in the recovery and utilization of REEs in clean energy technologies and provide perspectives for emerging areas of research and needs in rare-earth separation and utilization.

In this review, we will first present the unconventional sources suited for extraction of REEs, followed by a comprehensive review of methods for recovery of REEs by traditional separation methods; such as precipitation, ion-exchange, liquid–liquid extraction, and adsorption, as well as emerging electrochemical separation processes such as electrodialysis, electrochemical dissolution, and electrodeposition which have been used for REE recovery to reduce chemical consumption and increase efficiency. We will then discuss REE applications for sustainability and clean technologies, focusing on the electrochemical processes, and end with perspectives on the current challenges and opportunities.