Beam damage in operando X-ray diffraction studies of Li-ion batteries

Operando powder X-ray diffraction (PXRD) is a widely employed method for investigation of structural evolution and phase transitions in electrodes for rechargeable batteries. Due to the advantages of high brilliance and high X-ray energies, the experiments are often carried out at synchrotron facilities. It is known that the X-ray exposure can cause beam damage in the battery cell resulting in hindrance of the electrochemical reaction. In this study, we investigate the extent of X-ray beam damage during operando powder X-ray diffraction synchrotron experiments of battery materials with varying X-ray energies, amount of X-ray exposure and battery cell chemistries. Battery cells were exposed to 15, 25, or 35 keV X-rays (with varying dose) during charge or discharge in a battery tests cell specially designed for operando experiments. The observed beam damage was probed by µPXRD mapping of the electrodes recovered from the operando battery cell after charge/discharge. Our investigation reveals that beam damage depends strongly both on X-ray energy, amount of exposure and that it depends strongly on the cell chemistry, i.e. the chemical composition of the electrode.