Operando synchrotron XRD measurements of the FMO thin film during (dis)charging were performed at the BL02B2 beamline of SPring-8 in Japan. To prevent exposure of the FMO and LCO thin films to moisture in the air during (dis)charging, the sample was placed in a sample holder equipped with a polyimide dome, as shown in Fig. , and 100% He was flowed inside the dome. X-rays with an energy of 15.5 keV and a beam size of 1 mm x 20 µm were incident on the FMO thin film from outside the dome at an incident angle of 0.5°. The XRD profiles of the FMO thin film during (dis)charging were then collected using a high-resolu-on onedimensional solid-state detector (MYTHEN) . The exposure -me was set to 60 seconds for measurements at (dis)charging rates of 0.4C and below, 30 seconds for measurements at 1C and 2C (dis)charging rates, and 10 seconds for measurements at higher rates.