A physics-based model explaining stress-induced degradation in composite cathode for all-solid-state batteries

All-solid-state batteries (ASSBs) offer improved safety and energy density compared to conventional liquid–electrolyte systems, yet their widespread adoption is hindered by complex electro-chemo-mechanical degradation mechanisms. In this work, we introduce a stochastic continuum framework to capture microstructural heterogeneity and its influence on interfacial degradation in ASSBs. The approach combines physics-based modeling of electro-chemo-mechanical coupling, including a traction–separation law for interface decohesion, with non-Gaussian, spatially correlated random fields representing the variability of solid electrolyte properties. Random fields are constructed via a Gaussian translation method with Gamma marginals and a copula-based correlation structure, enabling realistic representation of particle-scale property fluctuations while maintaining computational efficiency. Numerical simulations on a representative half-cell of NMC811 cathode particles embedded in LPSCl electrolyte demonstrate the emergence of localized stress concentrations and interface damage under cyclic charging. The model quantitatively captures the evolution of specific differential capacity and depth of discharge, revealing how heterogeneous electrolyte properties amplify interfacial failure and drive catastrophic degradation. This framework provides a versatile tool for predictive design and reliability assessment of ASSBs accounting for microstructural variability.