A model for diffusion and immobilization of Lithium in SiOC nanocomposite anodes

Authors: Peter Stein, Dragoljub Vrankovic, Magdalena Graczyk-Zajac, Ralf Riedel, and Bai-Xiang Xu

In order to simulate the diffusion of Li ions in SiOC nanocomposites, we developed a reaction-diffusion model for multiphase materials. This model extends existing models for single-phase diffusion through consideration of the ion transport across material interfaces. In each phase, this model regards mobile and immobilized ions together with the irreversible trapping process. The behavior of material interfaces is incorporated using a Butler-Volmer reaction kinetics model. The model is verified using a simple two-phase benchmark on a square domain. Simulations of the coupled diffusion in a random microstructure show a stalling effect, whereby the immobilization process effectively stops the diffusion of mobile ions during the first stages of intercalation.

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