Reduction of ZrO2 in LiCl-Li2O Melt During Electrolysis

Reduction of spent nuclear fuel (SNF) components to metals during the electrolysis of the LiCl-Li2O melt at 650 degrees C is extremely important in the framework of the development of fuel reprocessing technology. In the present paper the ZrO2 reduction by lithium during the electrolysis of the LiCl-Li2O melt at 650 degrees C was studied. Cathode processes on a molybdenum substrate in contact with different ZrO2 samples (powder, pressed pellet, dense ceramic) were analyzed using cyclic voltammetry and electrolysis. It was shown that the appearance of ZrO2 near the molybdenum cathode leads to increasing cathode currents and decreasing lithium oxidation current. Both effects indicate the consumption of reduced lithium for the reduction of ZrO2 samples. In order to analyze the reduction products X-ray phase analysis and scanning electron microscopy were used, and to estimate the reduction degree of ZrO2 samples three methods were tested: dissolution of samples in inorganic acid solution, dissolution of samples in EtOAc/Br-2 solution, and carbothermal reduction. It was shown that during the electrolysis of dense samples only the lithium zirconate (Li2ZrO3) was formed at their surfaces, whereas the electrolysis of ZrO2 powder samples resulted in the formation of Li2ZrO3, Zr3O, and ZrO phases.

Automated summary

The reduction of spent nuclear fuel components to metals is crucial for the development of fuel reprocessing technology. This study investigated the reduction of ZrO2 by lithium during the electrolysis of LiCl-Li2O melt at 650°C. It was found that the presence of ZrO2 led to increased cathode currents and decreased lithium oxidation current, indicating the consumption of lithium for the reduction of ZrO2 samples. X-ray phase analysis and microscopy techniques were used to analyze the reduction products, and it was observed that lithium zirconate (Li2ZrO3) was formed during the electrolysis process.