Electrowinning of Metallic Lithium from Molten Salts

As lithium metal is expensive and is widely used as a anode material of lithium primary battery, reducing the cost of production is required by improving the process. In current method, metallic lithium is produced by using molten eutectic LiCl-KCl electrolyte. This process has some problems. At first, the source of lithium ion for cathodic reaction is the electrolyte itself. This means that LiCl in the electrolyte is consumed in the progress of electrolysis and that LiCl must be fed into the electrolyte continuously to keep the composition. At second, the working temperature of the electrolysis is considerably higher than the melting point of lithium. Furthermore, LiCl is expensive and is not easily handled due to its hygroscopicity. To reduce the cost for producing lithium, new process using other materials for the source of lithium is required. An alternative material is assumed to be Li2CO3 that is less expensive and is stable in the atmosphere. Another electrolyte other than LiCl-KCl eutectic should be searched to decrease the working temperature. Authors successfully used Li2CO3 as a lithium source for producing Al-Li alloy at 973K and obtained high current efficiency of about 95%. Fray also tried to produce lithium by using chloride-carbonate melt. However, the working temperature is still high, about 800K. In this work, it was tried to deposit lithium in LiCl-KCl eutectic and the condition of deposition was studied based on the electrochemical measurements and the current efficiency.