A phase field model to guide the development and design of next generation solid-state-batteries

The major bottleneck towards large-scale electrical transport is the restricted energy density and safety issues of current Li-ion batteries. Solid-state-batteries are intrinsically more safe and promise higher energy densities.

However, their power densities are far below the demands. One of the key challenges is to understand this limitation, which is determined by the complex interplay of charge transport processes.

Current modelling approaches are not able to predict the properties of these next generation systems, which requires introduction of a physically realistic Gibbs Free Energy, the exact shape of which determines the locally large Li-ion concentrations and strong ion-vacancy interactions in solid-electrolytes.

The associated computational challenge is the very fine and inhomogeneous finite element grid, necessary to describe the atomic-scale processes a the interfaces in macroscopic complete batteries. Here we propose a fundamental approach by integrating detailed Free Energy functionals for the solid-electrolytes, determined by first principle methods, into current state-of-the-art Phase Field models.

The correct physical description on the atomic-scale will result in a realistic general description of the interfaces, that play a pivotal role in solid-state batteries. The proposed model will boost the understanding and guide the design of these important next generation battery systems.