Fig. 1

First cycle electrochemical and structural behavior of LMR-NMC. a First and second cycle voltage profiles of LMR-NMC at a 4 mA g⁻¹ current density, showing the irreversible drop in voltage after charging through the 4.50 V plateau. The red dashed trace is the voltage profile when the material is cycled below 4.35 V. Inset: dQ dV⁻¹ plots. Voltages here and in all other plots are measured against a lithium counter electrode. b Synchrotron XRD patterns throughout the first cycle showing the loss of in-plane superstructure peaks (red dashed box) after charging through the 4.50 V plateau. The in-plane structure is not recovered during discharge, indicating an irreversible rearrangement in the cation ordering. c Fraction of the TMs in the Li layer (TM_Li) throughout the first cycle, obtained through refinement of the crystal structure to the XRD patterns, showing the substantial increase in out-of-plane disorder during the plateau. The TM migration is hysteretic and the material never fully recovers the pristine structure. Error bars representing the refinement error are smaller than the data symbols and are therefore omitted