Influence of alkaline pre-treatment on acid dissolution of cathode material of 18650 lithium battery

Abstract

Abstract Lithium battery cathodes contain lithium, cobalt, nickel, and manganese. Recycling of spent lithium batteries aims to recover these elements for re-use. Liberation of cathode materials from other metals in the battery such as aluminium, copper, and iron, is essential to obtain a good leaching efficiency in the recovery of valuable metals from end-of-life lithium batteries. This study investigates the behaviour of cathode materials and other metals in spent 18650 lithium batteries during leaching in H2SO4 solution with and without NaOH pre-treatment. Dissolution of aluminium using NaOH is a selective method to separate the metal from other elements. The influence of a 2-hour NaOH pre-treatment on subsequent acid leaching of cathode materials was investigated at both room temperature and 80°C. The extraction of aluminium increased to 75% at a higher temperature. Lithium concentration in the pregnant leach solution from acid leaching also increases with NaOH pre-treatment. The pre-treatment had a negligible effect on nickel, manganese, iron, and copper extraction. However, the cobalt extraction with NaOH pre-treatment was significantly lower. The result was likely due to indirect impact of less hydrogen gas was generated from a lower Al amount. The lattice structure of the leach residue for the sample with NaOH pre-treatment was monoclinic rather than rhombohedral due to stronger delithiation.