The regeneration by electrode reconstruction is an effective method and includes replenishing lithium with molten salt containing lithium [46, , , , ], de-lithiation [18, 37], or re-lithiation through electroosmosis and electrochemical methods (Table 12). Table 12.
The latest research status of direct regeneration of spent lithium–ion batteries was reviewed and summarized in focus. The application examples of direct regeneration technology in production practice are introduced for the first time, and the problems exposed in the initial stage of industrialization were revealed.
There are three main strategies for the recovery of cathode materials in lithium-ion batteries, namely, pyrometallurgy, hydrometallurgy and direct regeneration. Pyrometallurgy is the use of high-temperature techniques like pyrolysis, roasting, or melting to separate the necessary components from the cathode material .
Jung et al. reported a green closed-loop regeneration method to recover lithium by electrodialysis using LiOH and Li 2 CO 3 as the extractants and precipitants, respectively. The ionothermal lithiation method can directly regenerate spent LiBs. This is a green closed-loop process as ionic liquids can be reused.
Jung et al. reported a novel hydrometallurgical electrodialysis method to regenerate spent lithium cathode materials with lithium hydroxide (LiOH) or lithium carbonate (Li2CO3) to replace the impurities and used a three-compartment electrodialysis cell to regenerate LiOH and sulfuric acid (H2SO4) in recovering lithium.
After the separation of pretreatment to obtain the cathode electrode material, to regenerate the cathode electrode material from the leaching solution through the indirect regeneration strategy, it is necessary to use the appropriate reagent to leach the metal. The commonly used leaching methods are summarized in Fig. 4 a. Fig. 4.