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

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%.