The EIS measurement results at different experimental stages, namely at the beginning of the experiment (#1), at peak water content (#2), and at the lowest water content point after switching to dry gas for around 15 mins (#3), are illustrated in Fig. . The water content measured by neutron imaging and assessed by attenuation of the neutron beam at various positions is shown in Fig. (the corresponding total water distribution across the entire active area, the height of the 3D mapping is proportional to the water thickness in mm). For #1, the internal water content is approximately 0.022 g and exhibits a uniform distribution as little water is present. The Nyquist plot confirms this by having a larger intersection with the real axis (higher membrane resistance) and smaller arc (indicating low mass transfer resistance). In contrast, for #2, a significant amount of liquid water (0.213 g, an order of magnitude higher) is observed, primarily present in the channel regions. Although the intersection with the real axis shifts to the left at this stage, the impedance points in the low-frequency region, both on the real and imaginary axes, show a larger value, corresponding to a lower cell voltage (Fig. ).