Recycling of EoL Batteries with Ultrasonic Assisted Nitric-Ascorbic Acid Leaching: Experimental Design and Process Optimization

In recent years, the expansion of lithium-ion battery (LiB) applications and the growing demand for electric vehicles have led to a rapid increase in the amount of battery waste. This situation has made recycling processes important in terms of environmental sustainability and critical metal supply security. Hydrometallurgical processes are characterized by high metal recovery efficiency and low energy consumption. In this study, the black mass obtained from end-of-life (EoL) LiBs was dissolved by an ultrasonic assisted leaching method using HNO₃ (NA) and ascorbic acid (AA). The black mass contained about 40% graphite and consisted of LCO, NMC and LMO active cathode materials. During the leaching process, AA exhibited a synergistic effect with HNO₃, functioning as both a reducing agent and a complexing agent. The effects of parameters such as NA concentration, AA concentration and time were investigated using Taguchi experimental design method and optimized by ANOVA analysis. As a result of the study, over 98% dissolution efficiency was obtained for Li, Co, Ni and Mn with 0.5 M HNO₃, 0.1 M AA and 15 min leaching time. This method is characterized by low acid consumption, short process time, and industrial applicability.