Electrochemo-mechanical response of all solid-state batteries: Finite element simulations supported by image-based 3D reconstruction of X-ray microscopy tomography

Diffusion-induced stress (DIS) generation in the microstructure and contact loss at the active material (AM)/solid electrolyte (SE) and active layer/current collector interfaces strongly affect the electrochemical and mechanical stabilities of all-solid-state batteries (ASSBs). A fully coupled chemo-mechanical model based on the 3D microstructure of ASSBs reconstructed via synchrotron transmission X-ray microscopy tomography was established to analyze the voltage profile of different Young's modulus matching factors for AM and SE, singular DIS generation, and interfacial failure in ASSBs. The working voltage plateau of the ASSBs increases with the Young's modulus of the SE, while the voltage oscillation at the beginning of the delithiation process was attributed to the chemical potential difference between the various points of the active particles. Stress and deformation are key factors affecting the interfacial stability of ASSBs. A singular stress field, in which strain localization preferentially occurs in AM particles, results in complex interfacial failures in ASSBs. Theoretical considerations suggest that an interlayer combining high interfacial toughness with a sufficient electron transport coefficient will prevent the delamination of ASSBs by making strain localization away from the current collector. The established model explains the electrochemo-mechanical behavior in response to different mechanical properties of AM and SE and the interfacial failure mechanism of ASSBs, which in turn will offer guidance in the design of future ASSBs.