Modeling oxygen loss and phase transformation in Ni‐rich cathode materials: Impact of electrode microstructure

Nickel‐Manganese‐Cobalt (NMC) oxides are widely used as cathode materials in lithium‐ion batteries. While increasing the nickel content increases the available capacity in a given voltage window, it also reduces the structural stability of the material when cycled to high cutoff voltages. Oxygen release from the crystal structure as well as a layered‐to‐rocksalt phase transformation of the layered oxide material cause capacity loss and impedance rise. In this work, we propose a continuum approach to model oxygen release and the associated phase transformation using a 1+1D model informed by atomistic simulations to predict the thickness of reconstructed active material over time. An efficient interface model allows us to combine this approach with 3D microstructure‐resolved simulations in order to study the effect of a resistive layer on a real cathode microstructure. This novel workflow enables us to investigate the effect of individual electrode properties on the phase transformation and guide future electrode design.