Environmentally friendly and economic method for recovery of metals from spent lithium-ion batteries using ethylenediaminetetraacetic acid disodium salt and citric acid

Abstract

The recovery of lithium (Li), cobalt (Co), and nickel (Ni) from spent lithium-ion batteries (LIBs) has been targeted through leaching with environmentally friendly agents, aiming for lower chemical usage and reduced costs. The leaching agents employed in this study include ethylenediamine tetraacetic acid disodium salt (EDTANa₂), citric acid (CA), and a mixture of EDTANa₂ + CA. When the leaching process was carried out under the optimum conditions of 180 min, 100 °C, 20 g/L solid–liquid ratio and 1–4 % H₂O₂ (w/w), the lithium, cobalt recovery rate from spent LIBs was over 99 % for EDTANa₂ and EDTANa₂ + CA. Under the same conditions, the recovery of cobalt (93 %) and lithium (96 %) by CA reached a lower leaching efficiency. Nickel recovery was approximately 90 % for all leaching agents. For all three leaching agents, it was understood that chemical control was less effective in leaching reactions and the rate-limiting step was the porous layer transfer mechanism. When EDTANa₂ + CA was used as a leaching agent for Li, Co and Ni recovery from waste LIBs, the amount of matter was reduced by about 65–85 % and the leachate cost was reduced by 48–95 % compared with other leachates. All the results show that the EDTANa₂ + CA mixture can be used as an environmentally friendly leachate for recycling spent LIBs with less matter, lower cost and high-efficiency process.