Chemical affinity guided high-valence metal oxide interphase engineering for upcycling of ternary cathodes from electric vehicles

Abstract

The efficient regeneration and upcycling of spent ternary cathode materials from end-of-life electric vehicle batteries are essential for realizing a sustainable lithium-ion battery ecosystem. Interfacial engineering with high-valence metal oxides can in principle upgrade the performance of spent cathodes, however, the practically introduced interfacial layers are often nonuniform across the surface, which ultimately compromises the electrochemical performance. Herein, we propose an intermediate interphase strategy that leverages chemical affinity to achieve homogeneous interfacial modification. Formed on the surface of spent single-crystal LiNi0.55Co0.15Mn0.30O2, the lithium molybdenum oxide intermediate layer (Li-Mo-O) serves as a reactive scaffold that guides Nb2O5 to form a uniformly distributed lithium niobium oxide interphase (Li-Nb-O), which is widely known for its high Li + conductivity and excellent chemical stability. The strong affinity between Li-Mo-O and Nb2O5 yields a conformal Li-Mo-O/Li-Nb-O interphase (~10 nm) that accelerates Li + transport, suppresses parasitic surface reactions, and mitigates Ni dissolution. Consequently, the regenerated Ni55 delivers a reversible capacity of 207.7 mAh g -1 at 0.1 C, retaining 91% of its capacity after 200 cycles and 81% after 400 cycles at 1 C in the high-voltage range of 2.8-4.55 V vs. Li + /Li, as well as 90% after 300 cycles at elevated temperature of 50 o C. This work establishes interphase homogenization via intermediate layer engineering as a general paradigm for sustainable upcycling of cathodes from end-of-life batteries.