Stress Properties and Modeling of Lithium-ion Pouch Batteries

Abstract:

Lithium-ion battery is an electro-thermo-mechanical coupling system. It is of great significance to study the mechanical properties during the charging and discharging processes. According to Linear Variable Differential Transformer (LVDT), the static stress properties at different states and the dynamic stress properties under different charging and discharging currents of single-cell Lithium-ion pouch battery are measured and analyzed. The effects of current, state of charge, historical operating conditions and other factors on the stress change of the battery are studied. Through goodness analysis of fit test and significance validation, a reliable multivariate regression model of stress properties is established. The research shows that there is a monotonous relationship between static stress and state of charge; dynamic stress is generated during the charging and discharging process, and as the charging current becomes larger, the dynamic stress will increase accordingly. The established battery stress model can well describe the stress changes of the battery at different charging phases and under different currents.