Recycling the cathode materials of spent Li-ion batteries in a H-Shaped neutral water electrolysis cell

[Display omitted] •A large pH gradient is generated in a neutral water electrolysis cell.•The pH gradient allows concurrent LiCoO2 leaching and Co(OH)2 precipitation.•The use of external acid and base is avoided.•The Co(OH)2 and Li2CO3 recovered were calcined to resynthesize new LiCoO2.•The treatment of LiMn2O4 and NCM with this process was also investigated. The recycling of Li-ion batteries is becoming increasingly urgent due to the rapid accumulation of spent Li-ion batteries from aging portable electronics and electric vehicles. The lack of environmentally and economically feasible recycling technologies will not only cause material losses and environmental contamination, but also poses a serious limit for the penetration of more Li-ion batteries in electric vehicles and grid-scale energy storage applications. Here, we present a proof-of-concept demonstration of an innovative process for recycling cathode materials of Li-ion batteries in a neutral water electrolysis cell. During electrolysis, an electrochemical pH gradient was generated, which enables the leaching of waste LiCoO2 at low pH in the anode chamber and the precipitation of solid Co(OH)2 at high pH in the cathode chamber. The Co(OH)2 precipitates can be readily filtered and separated from the electrolysis cell. In addition, the Li+ is recovered in the form of Li2CO3. Unlike conventional hydrometallurgical processes and other aqueous electrochemical processes, this work harnesses the in-situ electrochemical pH gradient generated by neutral water electrolysis. This allows concurrent LiCoO2 leaching and Co(OH)2 precipitation at separate chambers and avoids the use of external acid and base, extractant or ion-selective polymer electrolyte membrane. This method is also extended to recycling waste LiMn2O4 and LiNi0.5Co0.2Mn0.3O2. Therefore, this new process represents a green advance for recycling the waste cathode materials of the Li-ion batteries.