Figs. 4a and 4b present the evolu-on of the FMO main peak during lithia-on/delithia-on and the voltage curve of the thin film, respec-vely, at various (dis)charge rates ranging from 0.15C to 15C. Due to an equipment malfunc-on during the measurement, the la5er half of the charging data and the first half of the discharging data were lost for the voltage curve at 0.15C. While the FMO thin film showed a degraded (dis)charge capacity of 74-78% of the theore-cal capacity at a rate of 15C, it exhibited a (dis)charge capacity close to the theore-cal value at lower rates. Regardless of the (dis)charge rate, the peak posi-on changed monotonically with lithia-on/delithia-on in a broad capacity range, and the transient broadening of the peak widths was observed in the middle stage of lithia-on/delithia-on. As shown in these figures, despite varying the (dis)charge current by two orders of magnitude, the peak evolu-on behavior during lithia-on/delithia-on appeared to be nearly independent of the (dis)charge current. To quan-ta-vely track the varia-ons of the posi-on and width of the FMO main peak during lithia-on/delithia-on at each rate, we fi5ed the main peak with a Gaussian func-on and es-mated its peak posi-on and full width at half maximum (FWHM). Fig. and illustrate the changes in the posi-on and FWHM of the FMO thin film during lithia-on and delithia-on, respec-vely, at various (dis)charge rates. At all (dis)charging rates, the peak posi-on monotonically decreased and increased during lithia-on and delithia-on, respec-vely, with a temporary increase in FWHM in the intermediate capacity range. The differences in the peak posi-on and FWHM between various (dis)charge rates were insignificant. Addi-onally, no systema-c changes in the varia-on of the peak characteris-cs were observed with respect to the (dis)charge rate. These results suggest that the lithia-on/delithia-on behaviour of FMO on a solid electrolyte is not rate-dependent, and thus is not governed by kine-c factors. To further inves-gate the influence of kine-c factors, we examined the evolu-on of the FMO peak during the open-circuit period following high-rate lithia-on. As depicted in Fig. , the FMO thin film was lithiated at 15C to approximately 1.2 µAh/cm 2 , a capacity at which dis-nct peak separa-on was observed with the FMO in the liquid electrolyte