Lithium-ion batteries (LIBs) possess remarkable advantages over other secondary batteries, including high energy density, high output power, and strong cycle stability. With the increase in portable electronic devices in recent years, there is a rising demand for LIBs. Furthermore, the large-scale deployment of electric vehicles in the upcoming years results in high demand for LIBs. However, the LIBs have a short life span of about 1−3 years for portable electronic devices and around 5−8 years for electric vehicles. The LIBs need to be replaced when the battery capacity depletes to about 70−80% of the initial capacity. It is estimated that the amount of spent LIBs will reach 97.7GW·h by 2025, posing a significant environmental hazard. The active cathode materials containing several high-value metals such as Ni, Co, Mn, and Li, if fully recycled, can significantly relieve the pressure from the high demand for resources.

At present, the recovery of valuable metals from the cathode materials of spent LIBs has been conducted through pyrometallurgical and hydrometallurgical recycling routes, or a combination of both. Some hydrometallurgical processes suffer from drawbacks of relatively long leaching times and relatively low efficiency. Moreover, the extensive use of concentrated acids and reductants, along with multiple process steps, results in significant effluent generation, exacerbating secondary pollution from the discharge of acidic wastewater and gas during the leaching process. Lithium is also dispersed amongst the separation and refining stages, leading to low lithium recovery. While some conventional pyrometallurgical methods offer high rates of chemical reactions and large treatment capacity, they may suffer from low selectivity and lithium recovery. Hence, continuous research and development are necessary to enable more efficient extraction and separation of valuable metals from spent LIBs.

This presentation will briefly discuss pretreatment, hydrometallurgical, and pyrometallurgical processing methods for extracting critical metals from spent LIBs. Ongoing research efforts from my team at Central South University will also be presented. Guided by high-temperature thermodynamics, we have proposed and experimentally investigated innovative processes. Our research aims to significantly improve the selectivity of pyrometallurgical processes and enhance the recovery rate of critical metals, particularly lithium.