Simple and efficient selective extraction of lithium from spent ternary lithium-ion batteries via oxidation/de-lithiation using NaClO

Abstract

Selective lithium recovery from spent lithium-ion batteries (LIBs) is attracting attention due to the large consumption of lithium for battery manufacturing. In this work, a novel method is proposed for selective extraction of lithium from spent ternary nickel–cobalt-manganese (NCM) LIBs under near-neutral pH and oxidative conditions by using NaClO as oxidant. The results shows that NaClO addition is the key to realize the selective extraction of lithium from the layered NCM structure under a non-acidic environment. Interestingly, the cracking and phase transition of spent cathode particles, which generally occur during electrochemical degradation, were also observed via NaClO oxidation in this work. Due to the unique properties of the spent NCM cathode particles, NaClO was activated catalytically in situ and generated highly active, electrophilic oxygen species such as OH, 1O2, and O2−, which were confirmed by quenching experiments. Their generation can further facilitate the oxidation/de-lithiation process and improve lithium extraction efficiency. As a result, approximately 92.54% of lithium was leached out from spent NCM cathode materials with >99% selectivity under the optimized leaching conditions (20 g/L solid-to-liquid ratio, 8% NaClO volume fraction, pH 7–8, 6 h, and room temperature). The purity of recovered Li2CO3 can reach to around 99.02% in the absence of purification process. The proposed method is operationally simple and safe because it is performed under near-neutral conditions (pH 7–8) and room temperature. Furthermore, NaClO is inexpensive, making this method attractive for application.