AlCl₃ -assisted dissolution of NdCl₃ in organic solvents for Nd refining

Reliable access to Nd-containing mineral resources and their effective future use and recycling are crucial for the sustainable development of industries based on rare earth metals. As a precursor for room-temperature Nd electrodeposition, NdCl3 is advantageous due to its abundance, low cost, and high availability; however, it is poorly soluble in most specialized ionic liquids and is therefore not widely used in solvometallurgical processes. Herein, we develop a practical means of Nd electrodeposition from a solution of NdCl3 and AlCl3 in 1,3-dimethyl-2-imidazolidinone, revealing that Al electrodeposition does not occur at the employed AlCl3 concentration. Instrumental and electrochemical techniques are used to confirm the electrodeposition of Nd on high-purity Al substrates, and together with theoretical calculations, these techniques are employed to probe the mechanism of NdCl3 dissolution, the electrolyte structure/composition, and the electrochemical behavior of the Nd-containing electroactive species. Our findings provide a strategy and theoretical basis for the cost-effective electrowinning of rare earth metals from their chlorides as upstream precursors.