A Green and Cost-Effective Method for Production of LiOH from Spent LiFePO4

An environment friendly and cost-effective process has been developed for production of LiOH from spent LFP cathode material. By using a suspension electrolysis system comprising an electrodialysis process, the spent LFP cathode material was oxidized and released lithium ion in the anode chamber, which is similar to that in the charging of an LFP battery. More than 95% of Li was leached and the current efficiency can reach up to 85.81%. And then the resulting lithium ion was migrated through the cation-exchange membrane and generated LiOH with OH– in the cathode chamber. High purity LiOH solution could be obtained due to the impurities in anode chamber being insulated by the monovalent permselectivity cation-exchange membrane. Kinetics analysis indicates that the delithiation process on the anode electrode was divided into two stages. In the first stage, the reaction rate was limited by the electrochemistry. Thereafter, it was controlled by the diffusion in the second stage. Finally, LiOH·H2O can be directly produced after evaporative crystallization via vacuum evaporation. A green close-loop process was then proposed, in which very little solid waste or wastewater is generated. Compared with other recovery processes, the proposed process has the highest profit due to the production of LiOH·H2O which is more valuable and no chemical regents being consumed.