Electro-chemo-thermo-mechanical phase-field model for lithium penetration in solid electrolytes

Abstract

The penetration of lithium (Li) dendrites through solid electrolytes (SEs) induces mechanical degradation and catastrophic short circuits in solid-state batteries (SSBs), posing a critical barrier to their commercialization. To address this, we develop a novel multi-physics phase-field model (PFM) that simultaneously simulates Li dendrite propagation and SE fracture. Unlike prior approaches, our model introduces two independent phase-field variables to decouple material damage and electrodeposition, enabling explicit resolution of the asynchronous crack growth and dendrite evolution observed in experiments. The model incorporates species diffusion, electric potential, reaction kinetics, heat transfer, mechanical deformation and fracture process within a thermodynamically consistent formulation. A staggered finite element scheme ensures numerical robustness for solving this highly nonlinear system. Representative numerical experiments are conducted to demonstrate the capability of the model in capturing complex deposition-induced fracture behaviors of SEs. The results highlight the role of Li nucleation location and microstructural heterogeneity in dictating the propagation pathways of dendrites. This work provides fundamental insights into the electro-chemo-thermo-mechanical degradation of SEs and offers design principles for advanced SEs in next-generation SSBs.