Development of a Highly Efficient Hydrometallurgical Recycling Process for Automotive Li–Ion Batteries

In this paper, an efficient and product-oriented hydrometallurgical recycling process including pre-treatment is developed to handle the spent automotive Li–ion batteries. The possibility to recover the high-grade graphite, cathode metal salts and lithium carbonate is investigated. In the designed process, leaching, solution refining, cathode metals precipitation and lithium carbonate crystallisation are implemented. The leaching efficiencies of valuable metals (Co, Ni, Cu and Li) are in the range of 98.6–99.9 % under the optimum conditions: 80 °C, 50 g/L of hydrogen peroxide, 2 mol/L of sulphuric acid or 4 mol/L of hydrochloric acid in 2 h. Meanwhile, the filtered graphite with purity of 99.8 % is obtained. In the following Cu cementation, an optimum temperature of 60 °C is found and the calculated activation energy of the cementation reaction is 12.9 kJ/mol. In the hydroxide precipitation, pH 3.5–4 is suggested for Al and Fe removal and pH 10 is high enough for cathode metal (Co, Ni and Mn) salts precipitation. The carbonate and sulphide precipitation methods are also demonstrated to be successful. In all, several marketable products are obtained, such as graphite, Cu powder, cathode metal salts and lithium carbonate.