Fully Coupled Multiphysics Modelling of Fracture Behaviour in Silicon Particles During Lithiation Delithiation Using the Phase Field Method

TL;DR

This paper presents a comprehensive multiphysics model to predict fracture and fatigue in silicon particles during battery cycling, incorporating effects of particle size, notch, charge rate, and porosity.

Contribution

It introduces a fully coupled phase field-based model for silicon particle fracture, including nanopore effects, to improve understanding of failure mechanisms in lithium-ion battery anodes.

Findings

Higher charge rates increase cracking and fracture.

Larger particle size accelerates failure.

Nanopores reduce stress and crack propagation.

Abstract

In this study, a multiphysics model fully coupling mass transport, deformation, phase field, and fatigue damage was developed to investigate the cracking and fracturing behaviours of Si particles during the single lithiation-delithiation cycle and fatigue damage during multiple cycles. The effects of particle diameter, charge rate, and pre-existing notches on the failure behaviour of Si particles were systematically analysed. The results showed that the increase in charge rate, particle diameter, and pre-existing notch length leads to larger cracking rates and faster fracturing of the particle. Then, a validated contour map of Si particle's fracture behaviours was developed. Additionally, the influence of pre-existing notch length and charge rate on fatigue damage was examined, and it was found that longer pre-existing notch length and larger charge rate can shorten the particle's cyclic life. Finally, to alleviate the particle fracture, nanopores were introduced in the particle, and the influence of porosity on the fracture behaviours was investigated. The results showed that nanopores can reduce expansion, dissipate global tensile stresses and elongate the crack propagation path. The developed computational framework established a predictive relationship between stress diffusion coupling theory and particle-level degradation, guiding future design and manufacturing of failure-resistant Si-based anodes for lithium-ion batteries.