Abstract
Performing high resolution 3D imaging with transmission X-ray microscopy (TXM) in an in situ battery system is extremely challenging. We show herein a method to conduct an in situ nano-X ray Computed Tomography (nano-XCT) experiment assisted by the in-line phase contrast technique for low Z elements in batteries. A carbon-based O2-cathode of Li-O2 battery was used for this investigation and the time-resolved 3D volumes were obtained and successfully reconstructed. Our approach is to perform a nano-XCT by zooming directly into a laser-shaped area not larger than 50 μm in an in-house in situ cell. The rotation axis of the tomography of this cell being parallel to the plan of the electrode, a specific method of preparing the electrode by laser is required. This method is essential in this approach, which allows to minimize the dead angles, align the beam and adjust the focus plan. We have demonstrated in situ observation of the difficult light species, lithium peroxide, in a lithium-oxygen battery. The time-resolved 3D volumes obtained showed a force pushing the analyzed area out of the field of view. This is due to the thickening of the lithium foil during the electrochemical process. Although X-ray Computed-Tomography (XCT) is often considered non-invasive and beneficial for the development of an in situ experiment for battery research, here we discuss the effect of the focused beam at the nanoscale with a focusing X-ray beam. The current contribution opens possibilities of characterization of battery materials by local in situ nano-XCT under realistic cycling conditions.