Upcycling Spent LiNi0.55Co0.15Mn0.3O2 Battery Cathode via High-Valence-Element Oxide Surface Engineering

The advancement of efficient cathode upcycling solutions of degraded batteries is paramount in light of environmental and resource considerations. Here, we introduce a one-step solid-state annealing approach employing nanosized MoO₃ as a surface treatment reagent and LiOH as a lithium compensation reagent to rejuvenate degraded single-crystal LiNi_0.55Co_0.15Mn_0.3O₂ cathodes from 110 Ah electric vehicle batteries. High-valence Mo species enrich along grain boundaries on the material surface, engendering a 5 nm thick amorphous Li–Mo–O interface layer that envelops the revitalized cathode particles with the recovered bulk structure, significantly bolstering ionic conductivity and resistance to undesired side reactions. As a result, the regenerated LiNi_0.55Co_0.15Mn_0.30O₂ achieves a reversible capacity of 184.2 mAh g^–1 at 0.1 C and retains 81% of its capacity after 450 cycles at 0.5 C, which outperforms current commercial material. A 120 mAh pouch cell with such a cathode maintains an impressive capacity retention rate of 80.6% even after 700 cycles at 1 C/0.2 C (charge/discharge).