A brief review of external physical field boosted low-temperature electrodeposition for metals and alloys

Electrochemical metallurgy at low temperatures (temperature <473 K) is promising for the extracting/refining metals and alloys in a green and sustainable way. However, the kinetics of electrodeposition process is generally slow at the low-temperature, which causes unexpected large overpotential and low efficiency. Thus, external physical fields are effective strategies for improving the mass transfer process and charge transfer process of electrochemical reaction. The rates of mass transfer and charge transfer determine the magnitude of overpotential and higher overpotential leads to lower energy efficiency, which in turn reduces the efficiency of the electrochemical process. In this review, we introduced the challenge in low-temperature electrochemical process. The recent achievements in the optimization of electrodeposition processes by applying an external physical field are briefly discussed. From the aspects of equipment and mechanism, summarized the regulating effects on optimization of electrodeposition process and selection strategies of diverse external physical fields, consisting of magnetic, ultrasonic and supergravity fields. Finally, advanced methods for in-situ characterization of external physical field-assisted electrodeposition processes are summarized to deeply understand of the metallic electrodeposition. In-depth mechanism of the external physical field on the electrode process is helpful for promoting the efficient of extracting metals at low temperatures.