Impact of Li₂O₂ Particle Size on Li–O₂ Battery Charge Process: Insights from a Multiscale Modeling Perspective

We report a comprehensive multiscale model describing charge processes of Li–O₂ batteries. On the basis of a continuum approach, the present model combines mathematical descriptions of mass transport of soluble species (O₂, Li⁺, LiO₂) and elementary reaction kinetics, which are assumed to be dependent on the morphology of the Li₂O₂ formed during discharge. The simulated charge curves are in agreement with previously reported experimental studies. The model along with the assumed reaction mechanisms provides physical explanations for the two-step charge profiles. Furthermore, it suggests that these charge profiles depend on the size of the Li₂O₂ particles, which are determined by the applied current density during discharge. Therefore, the model underlines the strong link between discharge and charge processes.