Radiation Induced Electrochemistry Suppression Probed by Spatially Resolved Operando X-Ray Diffraction

Abstract The use of synchrotron radiation has become common for probing the structure of rechargeable batteries, particularly for operando analysis of battery materials. In a recent operando X-ray diffraction study of graphite lithiation in a half cell we found that no lithiation of the sample could be observed in the XRD despite electrochemistry indicating full lithiation. Scanning the sample to examine other areas revealed that exposure of the electrode to high photon flux during the operando study had shut down local electrochemical transformations in the cell and caused formation of lithium fluoride. The effects are not limited to the irradiated area and a gradient of lithiation is observed in areas further from the operando beam position. We rationalize these changes through radiation induced ionization which may be caused by the direct beam, Compton scattered X-rays, or possibly both.