Figure (a) shows the SEM image of the thin-film LNMO electrode, where a dense polycrystalline LNMO layer, approximately 80 nm thick, is coated on the Pt current collector. EIS is obtained at different electrode potential, i.e., SOC, shown in Figure and. Due to the possible measurement artifacts in the high frequency range, the EIS analysis focus on the frequency range of 10 mHz to 2 kHz. The EIS spectra are fairly simple, consisting of one major time constant associated with kinetics at the high frequency region and a predominant diffusion impedance at the low frequency region. The outlier at 3.8 V, which equates to 0% SOC, exhibits significantly higher impedance with one convoluted time constant. Such EIS behavior is expected due to the sluggish kinetics at low SOC . Starting from 4.2 V onward, the kinetics-related impedance in the high frequency region decreases with elevated electrode potential (i.e., SOC). This can be associated with the intrinsic kinetic changes of the electrode materials. This is also the case for the state-of-the-art Ni-rich cathode materials . The variation of the diffusion impedance at different SOCs is more complicated. Nevertheless, the anomalous diffusion impedance is present for all the potentials beyond 3.8 V as indicated in the Nyquist plot (b), where the Warburg tail deviates from a vertical line, or in the Bode-phase plot (c), the phase angle at the low viii frequency is plateaued deviates from -90°.