The Impact of Lattice Stress on the Layered to Spinel Transformation of Li-Ion Battery Cathode Chemistries

The layered-to-spinel transformation of transition metal oxides is a major degradation mode in Li-Ion batteries LiMO 2 (M=Co, Ni and Mn). Transformation pathways for partially delithiated metal oxides have been investigated under lattice stress using the nudged elastic band method within density functional theory. We find that the relative stabilities and energy barriers of all steps along this pathway are significantly affected by local lattice strain, with high tensile strain destablising the undesired “Li-Mn” dumbbell structure, a recurring thorn in LiMnO 2 batteries. This yields insight into inhibiting degradation processes for layered Mn cathodes.