Speaker
Description
Reliable structural prediction in functional materials requires atomistic models that capture both the intended cation arrangement and the local disorder that control electronic behaviour. In this work, we study layered NMC622 using spin-polarized DFT simulations. The simulated cation ordering is benchmarked against experimental hybrid XRD–XAS measurements, validating that the structural models reproduce key features of the real material before their electronic properties are examined. Within these models, the calculated electronic structure shows signatures of localized, hole-like small polarons trapped on oxygen ions. Additionally, rather than appearing as a generic feature of the pristine layered structure, these oxygen-centered states emerge only in specific local structural and conditions. In particular, partial delithiation of local regions is required to create the relevant charge imbalance while TM_LI anti-site defects provide a local environment that stabilizes polaron trapping on oxygen. The results highlight the importance of predicting not only the average crystal structure of NMC cathodes, but also the local defect configurations that determine their electronic response. Thus, by linking cation ordering, lithium-vacancy environments, anti-site formation and oxygen-centered polarons, this work contributes to structural prediction towards understanding the highly correlated relationship between structure and property in complex battery materials.