Development of multi-scale structure homogenization approaches based on modeled particle deposition for the simulation of electrochemical energy conversion and storage devices

Abstract

In this work multi-scale homogenization approaches for porous electrodes are developed and compared. The results are used for the simulation of mass transport, and charge transfer processes at different active material loadings in various power sources, such as batteries, fuel cells and supercapacitors.A general pore-scale model is developed by mimicking the layer fabrication process. Electrode structures are virtually generated taking into account the interaction between the deposited particles during layer formation and surface relaxation. The effective transport and kinetic coefficients of the layers are calculated by different homogenization approaches and used in macro homogeneous models to predict macroscopic behaviour of fuel cells, supercapacitors and Li-ion batteries. The model predictions are compared with experimental kinetic and transport coefficients of fuel cells and supercapacitors and a good agreement was found.The results imply that porosity, tortuosity and specific surface area may follow a power law scaling with increasing deposited mass as a consequence of agglomeration during layer deposition. Consequently, effective transport and kinetic coefficients depend on the active material loading of the electrode.