Leaching of a mixture of cathode materials from spent lithium-ion batteries

The solution to the problem of recycling spent lithium-ion batteries is becoming one of the most pressing issues of our time. Given the significant increase in the production of lithium-ion batteries in recent years, a large amount of this type of waste, classified as hazard class 2, is expected to be generated in the next 5–10 years. This dictates the need for the fastest possible development of technologies and the creation of production sites for their processing. It is important to note that spent batteries contain such valuable materials as lithium, nickel, cobalt and manganese compounds, graphite and solvents. A method is proposed for obtaining an active cathode material from a mixture of spent lithium-ion batteries of household appliances and electronics with a product yield of 0.7 g/g of cathode. The chemical, phase and granulometric composition of the mixture of cathode materials, as well as their morphology and structure, were studied. Extraction of valuable components from this secondary raw material into a solution was carried out using acid reductive leaching. The effect of sulfuric acid and hydrogen peroxide concentrations in the range of 1–5 and 1–4 mol/l, respectively, temperature and solid/liquid ratio on the leaching degree was studied. It was noted that the process rate does not depend on the stirring rate in the range of 300–700 min–1. Optimum parameters for the material leaching process were determined. The study showed that the leaching cake is hollow particles of mixed cobalt (II, III) oxide. The apparent activation energy of the cobalt leaching process was calculated. It was found that in the temperature range of 20–40 оC the process occurs in the kinetic region of reaction, and at 40–80 оC the leaching rate is limited by internal diffusion.