Electrochemistry of Anodic Reaction in Molten Salt Containing LiOH for Lithium-Hydrogen Energy Cycle

To establish an efficient hydrogen storage and transportation system, LiH is a promising medium material because of its larger hydrogen storage capacity and easy handling based on its chemical stability. LiH generates hydrogen by reacting with H₂O and remains as LiOH as the by-product. In the system, LiOH must be returned to lithium metal to regenerate LiH again. The electrolytic winning of lithium metal from LiOH was investigated as part of the study on the hydrogen utilization system using LiH. However, LiOH reacts with lithium metal and makes the electrolysis difficult. Therefore, LiCl-KCl eutectic melt was used as the electrolyte, and the cathode and anode compartments were separated by a porous diaphragm in order to prevent contact between lithium deposited and LiOH in the electrolyte. The electrolysis was carried out by feeding LiOH into the anode compartment. As a result, the lithium metal was successfully obtained from LiOH without chlorine evolution by electrolysis with a high current efficiency, higher than 90%.