Efficient recovery and regeneration method of spent LiNi0.5Co0.2Mn0.3O2 cathode materials based on novel deep eutectic solvent design

Due to the increasing number of spent lithium batteries (LIBs), it is imperative to recycle spent LIBs to reduce environmental pollution and raw material consumption. Here, we present a novel deep eutectic solvent (DES) composed of guanidine hydrochloride with formic acid for spent LIBs the recycling to achieve rapid and efficient leaching of cathode materials from spent LIBs and synthesis of high-quality cathode material precursors in the DES leach solution. The multifaceted characterisation of the DES leach solution has revealed the mechanisms of the novel DES leached cathode materials. Under the optimal leaching conditions, the leaching rates of Li, Ni, Co, and Mn have been explored to be 99.79 %, 98.86 %, 99.51 %, and 96.12 %, respectively. More importantly, the DES leach solution addition of oxalic acid solution can be used to synthesise the precursor and to produce LiNi0.5Co0.2Mn0.3O2 with the recovered Li2CO3. Electrochemical test shows that the initial discharge specific capacity of regenerated LiNi0.5Co0.2Mn0.3O2 has 162.72 mAh g(-1), which is as good as that of commercial LiNi0.5Co0.2Mn0.3O2. The entire study accomplishes the regeneration of DES, and highly efficient recovery and regeneration of cathode materials from spent LIBs. This research provides a valuable alternate treatment for various DES leach cathode materials and an efficient new method for recycling spent LIBs cathode materials.