Zero-waste recycling of lithium and cobalt from lithium-ion batteries by three-stage electrodialysis

Abstract

Lithium cobalt(III) oxide (LCO) is an essential component of lithium-ion batteries (LIBs) in portable devices. Electrodialysis is being researched as a sustainable refining method in the recycling of these batteries, with low chemical input and few by-products. This study presents a novel process for zero-waste recycling of LIBs using three types of electrodialysis: metathesis, acid stripping and salt splitting. LCO was leached with sulfuric acid and hydrogen peroxide to bring metals into solution, whereafter cobalt (Co) was transferred to a negatively charged chelate upon addition of ethylenediaminetetraacetic acid (EDTA). Co sulfate (CoSO4) was used in a metathesis procedure to separate lithium (Li) from Co in the leachate, achieving a separation factor of 16.6 for Li and 41.9 for Co. The Li product was split into Li hydroxide and sulfuric acid using bipolar membranes. Sulfuric acid was added to precipitate EDTA from the Co product and 81.0% of the free acid could be stripped from the solution by electrodialysis. The Co product was evaporated and converted to CoSO4 upon thermal treatment. Some reagents could potentially be recirculated to achieve a zero-waste process but dilute products, low current utilization and membrane fouling are challenging and make the process less efficient.