Fig. 4(A) displays the digital photograph of
PVA gel electrolyte ribbon. To check the mechanical flexibility of
gel electrolyte, the ribbon of PVA gel electrolyte is bended at an
angle of 180 without any fracturing (Fig. 4(B)). Moreover, the ribbon
of PVA gel electrolyte is elastically stretched to about 3 times
than its original length (Fig. 4(C)). Further, it is observed that the
ribbon recover its original dimension when external applied force
is removed, pointing the excellent mechanical features of PVA gel
electrolytes. The excellent mechanical and elastic properties of
PVA gel electrolytes are useful to develop the high performance
flexible solid state supercapacitor.