Some Studies Of Electrolysis Of Solid Compounds In Molten Salts

High temperature molten salts have potential use in many areas due to their distinctive physical and chemical properties. Firstly molten salts are a crucial electrolyte for high energy density batteries technology for its high ion conductivity, wider electrochemical window and so on. On the other hand, due to the less energy consumption and less even no contamination of molten salt electrolysis, it will be one of the most important directions of development to prepare metals in the 21 century. So it is important to accumulate the knowledge and be engaged in the basic research in these areas.The reference electrodes are essental in the research of electrochemistry. These are no universal reference electrodes in the field of high temperature molten salts electrochemistry. In this work, we achieved reasonable ion conductivity of quartz in two ways and devised two wholly sealed Ag/AgCl reference electrodes, named as the ionized reference electrode and quartz reference electrode. Both reference electrodes are stable, temperature-reversible, contamination free to the molten salt, and re-usable in the same or different electrolyte systems. It was found that the former reference electrode could be used at temperatures ranging from 400 to 900°C and the latter 700-950°C.Till now there have been no appropriate methods to research the powder materials in high temperature molten salts. In this work, we prepared a W-SiO₂ powder microelectrode and molybdenum cavity electrode to study the electrochemical characteristics of various powdery materials in molten salts. Rationality and practicability of the electrode have been proved on a certain extent .The results provide a good basis for further research in this field.The preparation of Si from molten salts electrolysis is the potential replacement to the traditional way due to high reactive temperature, low product purity and CO₂ pollution. It was proven that Si could be prepared by electrolyzing the SiO₂ thin pellets directly in molten CaCl₂. Using pre-electrolysis and constant potentialelectrolysis with the aid of a quartz reference electrode, we can eliminate the impurities such as calcium and magnesium in molten salts and control the cathode potential accurately, aiming to prepare silicon with higher purity.Using the W-SiC>2 electrode prepared in this work, we studied in-depth the reduction mechanism of SiC>2 and illustrated the relationship between the reduction depth and reduction time of solid SiC>2 . It is very popular to prepare the metal materials through electrolyzing the electrode of solid oxide thin pellets directly. So it will have the universal sense to guide industrial scale production of metal materials.