context: Based on the above discussion, a driving mechanism of the EC procedures in the shoulder-by-shoulder structure was proposed (Fig. 2d) which is similar to that of a planar-arrangement supercapacitor. When both WO3 films were transparent during the first process, in essence, the conductive ITO layers were likely acting as two split capacitance plates. Once a working voltage was applied, Li ions were driven by the edge effect of the electric field of the capacitance plates and intercalated into the WO3 film at the negative potential, namely PI. Because the edge effect of the electric field was intense in the middle of the two EC films, more Li ions were injected into this area than into other areas, showing an uneven color distribution. These concentration differences resulted in the self-diffusion of Li ions in the colored film, namely PIII. However, when one EC unit was colored in the subsequent processes, it was likely acting as a charged capacitor. Once a reverse driving voltage was employed, the charge transfer procedure (namely PII) preferentially occurred. Electrons were transferred through the outer loop, while Li ions were transferred through the electrolyte, and they simultaneously intercalated into another EC film that was at a negative potential and colored it. The ions (electrons and Li ions) in the area of the colored film that was next to the middle of the two EC units were first transported into its counterpart and placed in the area that was also next to the seam because the electric field in the seam area was very intense. It is reasonable that PII is much quicker than PI because discharging a capacitor is a rapid process. When PII finished, the EC film was partly colored. Next, PI and PIII both occurred, and the partly colored film became completely colored. When the working voltage was turned off, the colored film became evenly colored, driven by PIII.