Anomalous interfacial stress generation and role of elasto-plasticity in mechanical failure of Si-based thin film anodes of Li-ion batteries

To understand the reason for mechanical failure and capacity fading of Si-based composite thin film batteries, we have developed a lithiation-induced interfacial stress model. The role of electrochemical charging reaction process, stiffness-induced elasto-plastic deformation and relative change in resistivity in detail through regional material heterogeneity sensitivity exponent has been accounted for anomalous interfacial stress generation. The insight gained from the results of state-of-health of the battery electrodes suggests that the transition of material from elastic to plastic behaviour and cracking at the interface are due to volume expansion, i.e., fully lithiated. Finally, the unified lithiation-induced stress model unravels the effect of embedded material heterogeneity parameters 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.