Leaching of Metals from Spent Lithium-Ion Batteries

The recycling of valuable metals from spent lithium-ion batteries (LIBs) is becoming increasingly important due to the depletion of natural resources and potential pollution from the spent batteries. In this work, different types of acids (2 M citric (C6H8O7), 1 M oxalic (C2H2O4), 2 M sulfuric (H2SO4), 4 M hydrochloric (HCl), and 1 M nitric (HNO3) acid)) and reducing agents (hydrogen peroxide (H2O2), glucose (C6H12O6) and ascorbic acid (C6H8O6)) were selected for investigating the recovery of valuable metals from waste LIBs. The crushed and sieved material contained on average 23% (w/w) cobalt, 3% (w/w) lithium, and 1–5% (w/w) nickel, copper, manganese, aluminum, and iron. Results indicated that mineral acids (4 M HCl and 2 M H2SO4 with 1% (v/v) H2O2) produced generally higher yields compared with organic acids, with a nearly complete dissolution of lithium, cobalt, and nickel at 25 °C with a slurry density of 5% (w/v). Further leaching experiments carried out with H2SO4 media and different reducing agents with a slurry density of 10% (w/v) show that nearly all of the cobalt and lithium can be leached out in sulfuric acid (2 M) when using C6H8O6 as a reducing agent (10% g/gscraps) at 80 °C.