Efficient Recovery of High-Purity Li2CO3 from Spent Li-SOCl2 Primary Batteries Through Thermal Treatment and Selective Hydrometallurgical Processing

Lithium-thionyl chloride (Li-SOCl2) primary batteries contain a large amount of lithium and are increasingly being produced as hazardous waste, but little work has been done on recycling these batteries. This study reports an efficient process for the recycling of Li from used Li-SOCl2 batteries using thermal treatment, water leaching and selective precipitation. The recovered black mass obtained after manual dismantling of the batteries contained 6.734 wt.% Li, which was thermally treated under different conditions to minimize lithium loss. Thermal treatment at 500 °C for 2 h limited Li volatilization to about 7%, but loss was significant at higher temperatures. Water leaching selectively recovered lithium into solution, leaving most of the impurities in the solid residue. Different precipitation strategies were assessed for the recovery of lithium as Li2CO3. Although ammonium carbonate yielded a recovery efficiency at 68%, sodium carbonate provided higher overall precipitation yields. Thus, the optimal conditions involved solution preconcentration, pH adjustment to above 11, and the use of ethanol as an antisolvent using sodium carbonate as a precipitating agent. These results reveal an efficient recycling pathway to recover lithium from spent Li-SOCl2 batteries, contributing to the sustainable management of this under-explored battery waste stream.