Acetate acid and glucose assisted subcritical reaction for metal recovery from spent lithium ion batteries

As a typical urban mineral resource, spent lithium ion batteries (LIBs) contain abundant valuable metal resources, such as Li, Co, Mn and Ni, but facile separation with environmental benignity is challenging. Although the organic acid leaching method has been proposed to address this issue, its application is still hindered by the limitations of low leaching efficiency, high acid consumption and relatively long treatment time. Here a green and simple intensifying method is demonstrated for facile leaching of high value metals from spent LIBs using subcritical water, which combines glucose as a reductant and acetic acid as a leaching agent. More than 97% of the four metals were effectively leached from spent LIBs in 67 min under optimal conditions. Furthermore, the mechanism of the hydrothermal reaction is elucidated. Hydrothermal activation can accelerate the dissociation of the crystal structure, and the large ionization constant of acetic acid assists in maintaining a constant supply of protons in the solution. In addition, glucose can promote the reduction of dissolved metal ions to a more soluble low-valent state, and decompose to other low molecular weight organic acids that can coordinate with metal cations to promote the dissolution of metals from the cathode material. As a result, the proposed use of organic acids and glucose in subcritical reaction manifests an effective, ecofriendly, economic and sustainable strategy for metals recovery of spent LIBs.