Direct Recycling and Upcycling of Spent LiNi_xMn_yCo_zO₂ (NMC) Cathodes in Molten Salts

With the rapid increase in lithium-ion battery (LIB) usage, addressing the proper handling of end-of-life (EOL) LIBs has become a critical challenge.¹ Recovering high-value cathodes from EOL LIBs not only alleviates the pressure on the raw material supply chain but also mitigates environmental pollution and minimizes wastes.² A novel “reciprocal ternary molten salts (RTMS)” system focused on the direct recycling and upcycling of Ni-rich cathodes with a particular emphasis on lithium-nickel-manganese-cobalt oxide (NMC) materials was developed.^3,4 This process restores the layered structure, lithium content, and electrochemical performance of NMC 622 to levels comparable to pristine material.³ Cost analysis reveals that cathode regeneration through this method is more economical than conventional recycling methods or virgin production. Additionally, the upcycling of spent NMC 111 to next-generation Ni-rich NMC cathodes was realized using the RTMS system.⁴ This innovative approach simultaneously incorporates nickel and relithiates the cathodes, resulting in Ni-rich materials with an α-NaFeO₂-type layered structure, restored lithium content, and excellent electrochemical performance. The regenerated cathodes closely match the pristine NMC materials, highlighting the potential of RTMS technology to maximize material value and support the sustainable development of LIBs.

References:
1. Fan, J., Luo, H., Wang, T. and Dai, S. Progress in direct recycling of spent lithium nickel manganese cobalt oxide (NMC) cathodes. Energy Storage Materials, 2024, 73, 103813.
2. Wang, T., Luo, H., Bai, Y., Li, J., Belharouak, I. and Dai, S. Direct recycling of spent NCM cathodes through ionothermal lithiation. Advanced Energy Materials, 2020, 10(30), 2001204.
3. Wang, T., Luo, H., Bai, Y., Belharouak, I., Jayanthi, K., Paranthaman, M.P., Manard, B.T., Wang, E.T.H., Dogan, F., Son, S.B. and Ingram, B.J. Direct recycling of spent nickel-rich cathodes in reciprocal ternary molten salts. Journal of Power Sources, 2024, 593, 233798.
4. Wang, T., Luo, H., Fan, J., Thapaliya, B.P., Bai, Y., Belharouak, I. and Dai, S. Flux upcycling of spent NMC 111 to nickel-rich NMC cathodes in reciprocal ternary molten salts. Iscience, 2022, 25(2), 103801.