In recent years, all-solid-state batteries (ASSBs) have attracted considerable attention within the scientific community owing to their potential for achieving high energy density, enhanced safety characteristics, and a broader operational temperature window. Specifically, sulfide-based solid-state electrolytes (SSEs) demonstrated the most promising ASSB chemistry with their room-temperature Li+ ionic conductivity comparable or exceeding to that of conventional liquid electrolytes (~10 mS cm-1). Our previous works showcased the superior cyclability of ASSB implementing sulfide-SSEs and carbon-free silicon anode with phenomenal stable cycling for 500 cycles1. Recently, we further demonstrated the scalability of carbon-free Si anode at the pouch cell level with cell capacity reaching 100 mAh under significantly low stacking pressure of 5 MPa2-3, showing promise to accelerate the development and commercialization of ASSBs.Characterizing ASSBs during and after operation is critical for their further development. Crucially, scaling up ASSBs to pouch-cell level introduces new challenges as characterizing the internal microstructure and morphological evolution at a larger scale becomes difficult and time-consuming. Previous works using destructive focus-ion beam-scanning electron microscope (FIB-SEM) can only visualize several tens of micrometers with long imaging times for 3D reconstruction up to hours. Thus, techniques with larger field of view (FOV) and shorter imaging time are inevitably needed to have a better statistical analysis. This study leverages the non-destructive nature of synchrotron X-ray micro-computed tomography (CT) to visualize the morphology and microstructure of each component within an ASSB pouch cell. Leveraging the large FOV of X-ray micro-CT, up to several millimeters and shorter imaging time, we are able to perform a quantitative analysis of the extracted microstructural information, including porosity, loss of contact, and tortuosity. These findings will provide a broader understanding of the structural evolution in ASSB pouch cells, bridging the gap between lab-level research and application-level production.Reference: Tan, D. H. S.; Chen, Y. T.; Yang, H.; Bao, W.; Sreenarayanan, B.; Doux, J. M.; Li, W.; Lu, B.; Ham, S. Y.; Sayahpour, B.; Scharf, J.; Wu, E. A.; Deysher, G.; Han, H. E.; Hah, H. J.; Jeong, H.; Lee, J. B.; Chen, Z.; Meng, Y. S., Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes. Science 2021, 373(6562), 1494-1499. Tan, D. H. S.; Meng, Y. S.; Jang, J., Scaling up high-energy-density sulfidic solid-state batteries: A lab-to-pilot perspective. Joule 2022, 6 (8), 1755-1769. Chen, Y.-T.; Jang, J.; Oh, J. A. S.; Ham, S.-Y.; Yang, H.; Lee, D.-J.; Vicencio, M.; Lee, J. B.; Tan, D. H. S.; Chouchane, M.; Cronk, A.; Song, M.-S.; Yin, Y.; Qian, J.; Chen, Z.; Meng, Y. S., Enabling Uniform and Accurate Control of Cycling Pressure for All-Solid-State Batteries. 2023.
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