Figure 4.

A) EIS spectra of symmetric K/GPE/K cell before and after polarization. The current profile response to the DC voltage step is shown in the inset. B) Potential vs. test time of potassium stripping and plating carried out in a symmetrical K/GPE/K cell at 0.1 mA cm⁻² and 0.5 mA cm⁻² (see the Supporting Information, Figure S1, which shows a zoomed portion of the experimental curve). C) Cycling performances of a Super‐P/GPE/K half‐cell tested at a specific current of 0.05 A g⁻¹ for 200 cycles.