Operando probing and adjusting of the complicated electrode process of multivalent metals at extreme temperature

Abstract

Nearly half of the elements in the periodic table are extracted, refined, or plated using electrodeposition in high-temperature melts. However, operando observations and tuning of the electrodeposition process during realistic electrolysis operations are extremely difficult due to severe reaction conditions and complicated electrolytic cell, which makes the improvement of the process very blind and inefficient. Here, we developed a multipurpose operando high-temperature electrochemical instrument that combines operando Raman microspectroscopy analysis, optical microscopy imaging, and a tunable magnetic field. Subsequently, the electrodeposition of Ti—which is a typical polyvalent metal and generally shows a very complex electrode process—was used to verify the stability of the instrument. The complex multistep cathodic process of Ti in the molten salt at 823 K was systematically analyzed by a multidimensional operando analysis strategy involving multiple experimental studies, theoretical calculations, etc. The regulatory effect and its corresponding scale-span mechanism of the magnetic field on the electrodeposition process of Ti were also elucidated, which would be inaccessible with existing experimental techniques and is significant for the real-time and rational optimization of the process. Overall, this work established a powerful and universal methodology for in-depth analysis of high-temperature electrochemistry.

Effect of electric fields on tungsten distribution in Na2WO4–WO3 molten salt

“…The high-temperature in situ Raman data were obtained by a multipurpose operando instrument for high-temperature electrochemistry, 35 as illustrated in Fig. 1a.…”

Review—Pulse-Electrolysis Protocols in High Temperature Molten Salt Electrochemistry

“…75,76 Multi-step cathode processes in high-temperature MSE can be successfully analyzed by using in situ Raman devices. 77 In addition to studying the properties of ions in the electrolyte in real time, it is necessary to further observe the morphologies of 66 electrodes in real time. Computed tomography (CT) is an important method for in situ analysis of electrode morphology.…”