全固体電気化学デバイス構成材料における応力誘起の化学ポテンシャル変調の実験的評価

抄録

Mechanical stress is being increasingly recognized as one of the factors that significantly affect the fundamental properties of the materials for solid state electrochemical devices, including batteries. However, the influence of stress has not been precisely understood because it is challenging to experimentally and quantitatively evaluate the relationship between the stress and the material properties. Here, we developed an experimental method to quantify the influence of stress on the chemical potential in a material and successfully evaluated the stress-induced Li chemical potential (μ_Li) modulation in a conventional battery electrode material, LiCoO₂ (LCO). Our results suggested that the stress-induced μ_Li modulation in LCO was anisotropic because of its anisotropic chemical expansivity. As well as LCO, many other electrode materials exhibit the anisotropic chemical expansivity, and they are subjected to highly anisotropic stress in the practical electrochemical devices. Thus, the findings in this study can provide valuable information for the design and development of the solid state electrochemical devices.