Modeling of Concurrent Reaction Driven Stress at Heterogeneous Composite Electrode-Collector Interface in Li-Ion Batteries: Elastic and Elasto-Plastic Analysis

Abstract

A model is developed to study the concurrent reaction driven interfacial stress for an elastically heterogeneous, isotropic bi-layer electrode free for deformation at one end. The slow and fast electrochemical charging reaction process and stiffness induced elasto-plastic deformation characteristics often arise during lithiation of composite electrode with high capacity. The analytical formalism of the stress generated at electrode-collector interface incorporates elasto-plastic behavior of the material and relative change in resistivity in detail through regional material heterogeneity sensitivity exponent. The elasto-plastic behavior and stiffness of the anode material (i.e., Si composite electrode) has been accounted as a non-linear function of Li-ion concentration and validated. The insight for initiation of cracking due to interfacial stress and state-of-health of the battery electrodes has also been discussed. Finally, unified lithiation-induced stress model unravels the effect of embedded material heterogeneity parameter coupled with resistivity and stiffness and its anomalous dynamics at composite electrode-collector interface. The verification with the available experimental data in the literature has also been made and hence providing a better insight into the origin of degradation and the evaluation of advanced battery electrodes.

Keywords: Composite layered electrodes, Lithiation-induced stress, Elasto-plasticity, Stiffness, Heterogeneity, Resistivity