Utilization of lithium sulphate electrodialysis for closed-loop LIB recycling: Experimental study and process simulation

The hydrometallurgical recycling of spent lithium-ion batteries (LIBs) frequently relies on sodium hydroxide and sodium carbonate. This process generates a sodium-enriched solution, requiring treatment prior to safe discharge. This study focuses on a closed-loop recycling process for spent Lithium Nickel Manganese Cobalt Oxide (NMC) cathode material, eliminating sodium ions from conventional hydrometallurgical methods and regenerating acid and precipitant from disposal slurry. It employs lithium hydroxide (LiOH) as the precipitating reagent, while lithium recovery is conducted employing electrodialysis (ED) to regenerate LiOH and sulfuric acid (H2SO4) from the lithium sulfate solution. A part of the LiOH and H2SO4 reagents are subsequently used for the leaching and precipitation steps, creating a closed-loop recycling process. An experimental setup was developed to study the leaching, impurity removal, and metal extraction processes. The closed-loop recycling process was further investigated by simulation of this process. This involved the development of the ED module in both continuous and batch configurations using the Aspen Custom Modeler. This ED module is incorporated into Aspen Plus to integrate with the recycling process under experimental operational conditions. The minimal deviations of 3.34% and 2.38% within the precipitation and co-precipitation processes indicated the accuracy and validity of this work. Utilizing multiple batch-mode ED cells yields a 25% higher recovery of LiOH solution compared to continuous ED cells in the same operation conditions, i.e., employing 48 cells for 96 min under a current density of 1100 A.m(-2). Furthermore, increasing the leaching temperature by 60 degrees C yields a 53% increase in lithium leaching efficiency.