First-principles computation of dislocation structures and stress-driven phase transformations in layered oxides for Na-ion batteries

Dislocation dynamics at the atomic scale play a significant role in phase transformations and mechanical degradation of layered cathode materials in Na-ion batteries (NIBs), yet their fundamental behavior remains poorly understood. Here, we employ first-principle calculations to investigate dislocation-mediated processes in a range of O3- and O'3-type layered transition metal (TM) oxides, Na(TM)O₂, with TM = Ti, Cr, Mn, Fe, Co, and Ni. Generalized stacking fault $$\gamma$$-surfaces are computed to quantify the influence of TM chemistry on stacking sequence energetics. These $$\gamma$$-surfaces, combined with elastic tensor data, inform a semi-discrete variational Peierls–Nabarro model to characterize dislocation core structures and Peierls stresses. Our results reveal narrow dislocation cores and partial splitting behaviors governed by the γ-surface topology and material elasticity. We further propose a dislocation-driven mechanism for the O3$$\leftrightarrow$$P3 phase transformation, wherein partial dislocation motion facilitates the broadening of stacking faults during desodiation. This work establishes a detailed first-principles computational framework for understanding dislocation-mediated degradation pathways in layered oxides, offering atomistic-scale insights for the design of more robust NIB cathode materials.