In situ synchrotron X-ray diffraction studies of lithium oxygen batteries

Lithium oxygen batteries were studied in situ by synchrotron X-ray diffraction. Crystalline Li2O2 was shown to form reversibly on a plain carbon cathode under normal cycling conditions. However, if the cell was polarized to induce electrolyte decomposition before the oxygen reduction reaction was initiated, LiOH was found to cycle reversibly on the cathode instead. A mechanism linking the LiOH production to the electrolyte decomposition was proposed.