Operando observation of dynamic dendritic formation and dissolution within the symmetric Zn||Zn cell was performed with a 4K digital microscope (Keyence VHX-7000, Japan). A 50× objective lens was used to obtain sufficient resolution of ca. 0.5 µm, resulting in a relatively large field of view (FOV) of 5.8 × 4.2 mm2. The image acquisition was synchronized with electrochemical measurements.