| 초록 |
Currently, Ni-rich layered LiMO2 (M = Ni, Co, Mn, and/or Al) compounds are considered ideal cathode materials for EV batteries because their high capacity enables EVs to achieve high mileage per charge. Although Ni-rich layered cathodes are advantageous in terms of energy density and material cost, in general, they have considerably decreased cycling lifetimes with inferior thermal stabilities, which hinder their commercialization. The inherent structural instability of Ni-enriched layered oxide cathodes, particularly in the deeply charged state, leads to a build-up of mechanical strain. In this study, we demonstrate that limiting the primary particle size of the cathode resolves the capacity fading problem as nano-sized primary particles effectively relieve the high internal strain associated with the phase transition near charge end and fracture-toughen the cathode. Particle size refinement, achieved by inhibiting the grain growth during lithiation through the introduction of a high-valence dopant, imparts the necessary mechanical toughness to counter the high internal strain associated with the phase transition near charge end. |
