Cost-effective direct regeneration of spent NCM cathode via solvothermal regeneration process

Abstract

With the rapid expansion of the electric vehicle market, managing spent lithium-ion batteries (LIBs) has become a critical environmental and economic challenge. However, conventional pyrometallurgical and hydrometallurgical processes have limitations, such as high energy consumption and secondary pollution. This study presents a simple direct regeneration process using an ethanol-based solvothermal treatment to obtain regenerated spent NCM. Through this solvothermal direct regeneration process, the NCM material regenerated at 130°C for 4 hours achieved a high discharge capacity, and the ST-NCM maintained an excellent capacity retention of 94.08% after 100 charge-discharge cycles.Morphological and structural analyses revealed that the solvothermal process effectively removed surface impurities and restored the disordered rock salt structure to a wellordered layered structure. Furthermore, the CO2 emissions of the regenerated NCM were only 1.01 kg/kg, representing a reduction of approximately 74% compared to pyrometallurgy (3.86 kg/kg) and approximately 66% compared to hydrometallurgy (2.98 kg/kg). This study presents an eco-friendly direct regeneration strategy that preserves the original metal composition while maintaining excellent electrochemical stability, offering a sustainable approach for the large-scale recycling of high-nickel lithium-ion battery cathodes.