Synthesis of Ni-Rich Cathode Material from Maleic Acid-Leachate of Spent Lithium-Ion Batteries

Abstract

The recycling and reclamation of spent lithium-ion batteries have attracted more and more attention. In the present study, maleic acid was employed to leach spent LiCoO₂ cathode materials. The leachate was then taken to synthesize LiNi₀.₈Co₀.₁Mn₀.₁O₂ materials through a coprecipitation and calcination process, where the leachate dosage was controlled at 0%, 20%, 40%, 60%, 80%, and 100%, separately. The results of X-ray diffraction showed that when leachate dosage was lower than 60%, the crystal structure of the materials was normal. However, when the dosage exceeded 80%, the crystal structure was negatively affected, and Li⁺/Ni²⁺ mixing was aggravated. The morphology of the materials became irregular when leachate dosages were 80% and 100%. Moreover, the ratio of Ni²⁺/Ni³⁺ in the materials increased as the leachate dosage increased. When the leachate dosage was lower than 60%, the electrochemical performance of the materials was reasonable. However, if the dosage exceeded 80%, the discharge specific capacity, cycling stability, and rate stability were significantly decreased, while the irreversibility, polarization, and impedance of the electrodes increased. In conclusion, maleic acid-leachate of spent LiCoO₂ materials can be used to synthesize LiNi₀.₈Co₀.₁Mn₀.₁O₂ materials, only if the leachate dosage is kept lower than 60%.