In-Situ Evaluation of Electrochemo-Mechanical Coupling Phenomena in Two-Phase Battery Electrodes

In solid-state energy storage devices such as solid-state batteries (SSBs), the constituent materials can be exposed to large stress. Such stress has been increasingly recognized to significantly alter the fundamental properties of constituent materials, including Li chemical potential, which governs the equilibria between phases. Therefore, the phase equilibrium in two-phase electrode materials can be altered by stress, potentially modifying the performance of these materials. However, the influence of stress on the two-phase materials is not fully elucidated. Here, we present our studies investigating the influence of stress on the properties of two-phase electrode materials such as LiFePO4 and Fe2(MO4)3. These works demonstrated that stress can significantly influence μLi, phase equilibria, and (dis)charge behaviour of these materials, and the thermodynamic influence of stress is essentially governed by the chemical expansion coefficient of the material. These findings expand our understanding of the role of stress in SSBs, contributing to their performance enhancement.