The obtained maximum value
of specific capacitance for PVA gel electrolyte based supercapacitor
device is the 112 F g1, which is much larger than the CMC and PEO
gel electrolyte based FSS-SCs (supporting Fig. 1(C)). The higher
specific capacitance for PVA gel electrolyte based supercapacitor
device is due to the higher ionic conductivity of PVA gel electrolyte
with more interface for electrochemical reactions. The estimated
value of specific capacitance for PVA gel electrolyte is much larger
as compared to previous report [18–20]. Further, the rate capability
of supercapacitor devices is studied by the measuring charge–
discharge at different constant current densities and presented in
Fig. 6(C). The asymmetric behavior of charge–discharge profile
interpreting the redox reactions occurs at the interface of electrode/
electrolyte. In comparison with supercapacitor devices with
CMC and PEO gel electrolytes (supporting Fig. 2(A) and (B)), the
PVA gel electrolyte based supercapacitor has longer charge–
discharge time. This is may be due to the more interface available
for redox reaction as the compatibility of PVA gel electrolyte is more
with active electrode than the CMC and PEO gel electrolytes.