A strain rate-dependent interfacial contact model by considering the strain rate and temperature of lithium for LLZO-based solid-state lithium batteries

The interfacial contact between the electrolyte and electrode is a crucial factor influencing the interface impedance in all-solid-state lithium batteries. This paper investigates the effects of temperature and strain rate of lithium metal on the interfacial contact and stress state of the Li-Li7La3Zr2O12 interface using the finite element method. To predict the plastic flow behavior of lithium metal, a modified Zerilli-Armstrong constitutive model is proposed over a wide temperature range (198 to 398 K) and strain rate range (4 x 10(-5) s(-1) to 2 x 10(-2) s(-1)). Based on the experimental data, the parameters in the constitutive model of lithium are determined based on gray wolf optimizer. After optimizing the parameters, the average absolute relative error is 6.22% and the correlation coefficient is 0.9882. Based on the finite element simulation, the effects of temperature and strain rate on the interface contact and stress state under different Li7La3Zr2O12 surface roughness are further analyzed. Results show that temperature and strain rate have significant effects on the interface contact and stress state. Specifically, the interfacial contact region increases with the decrease in the strain rate and with the increase in temperature.