Electro-chemo-mechanical analysis of the effect of bending deformation on the interface of flexible solid-state battery

Flexible solid-state battery has several unique characteristics including high flexibility, easy portability, and high safety, which may have broad application prospects in new technology products such as rollup displays, power implantable medical devices, and wearable equipments. The interfacial mechanical and electrochemical problems caused by bending deformation, resulting in the battery damage and failure, are particularly interesting. Herein, a fully coupled electro-chemo-mechanical model is developed based on the actual solid-state battery structure. Concentration-dependent material parameters, stress-dependent diffusion, and potential shift are considered. According to four bending forms (k = 8/mm, 0/mm, -8/mm, and free), the results show that the negative curvature bending is beneficial to reducing the plastic strain during charging/discharging, while the positive curvature is detrimental. However, with respect to the electrochemical performance, the negative curvature bending creates a negative potential shift, which causes the battery to reach the cut-off voltage earlier and results in capacity loss. These results enlighten us that suitable electrode materials and charging strategy can be tailored to reduce plastic deformation and improve battery capacity for different forms of battery bending.