Defective oxygen inert phase stabilized high-voltage nickel-rich cathode for high-energy lithium-ion batteries.

Pushing layered cathode to higher operating voltage can facilitate the realization of high-energy lithium-ion batteries. However, the released oxygen species initiate materials surface upon highly delithiated states will react severely with electrolyte, accelerating the structure deterioration and triggering the thermal degradation. Here we propose an inert phase of La ₂ Mo ₂ O ₉ with abundant oxygen vacancies (about 41%) by regulating the annealing temperature to engineer the cathode interface beyond conventional modifications. By employing LiNi _0.8 Co _0.1 Mn _0.1 O ₂ as a model system and extending to higher voltage-operated LiCoO ₂ and Li-rich cathode, we demonstrate that the introduced lanthanum and molybdenum ions will transfer electrons to enhance the surface oxygen electronegativities, thus served as "oxygen anchor" to alleviate oxygen evolution. Furthermore, the possible released oxygen can be operando captured and reserved by β-phase La ₂ Mo ₂ O ₉ depositor for the intrinsic high oxygen vacancy formation energy. The reaction involving oxygen species with electrolyte is fundamentally diminished, thus effectively mitigate the structure deterioration and elevate the electrochemical performances, enabling a 1.5-Ah pouch-type full cell to exhibit negligible 6.0% capacity loss after 400 cycles.
(© 2023. The Author(s).)