To further demonstrate the flexibility of the ICI method, an operando XRD experiment coupled with the ICI method was performed on cell 1 after 56 cycles. As depicted in Figure , when the 003 reflection (R3 R m) shifts to higher 2θ values, the diffusion coefficient drops over an order of magnitude and the internal resistance tripled. The shift of the 003 reflection starts at 4.1 V and accelerates at 4.2 V, which coincides with the start of the increase in internal resistance and the decrease in diffusion coefficient, respec-tively. The reverse can be observed during discharge. In addition, by comparing the patterns taken above 4.2 V with a previous operando XRD study on the same material in the first cycle, it can be observed that in the degraded cell here, the 003 reflection is composed of two rhombohedral phases with dissimilar c lattice parameters (Figure ). The exact mechanism for this phase separation is still debated, but most models attribute this to the ramifications of the formation of the degraded rock salt phase. Nevertheless, it is shown here that the ICI method can be easily combined with operando XRD and track the diffusion coefficient and internal resistance in real time, which constitutes a valuable method for further studies of the degradation mechanisms of this and other materials.