1) Using gel electrolyte (solid state or gel state eg PVA/H2SO4) as a separator between electrodes wont cause quick self discharge of EDLC due to gel conductivity?
2) If gel electrolyte is solidified will it still be conductive enough to form double layer with electrode material according to my understanding electrolyte should reach the pores of electrode material and solid state wont?
a recently published paper: Chemically Crosslinked Hydrogel Film Leads to Integrated Flexible Supercapacitors with Superior Performance. Hope help you!
1) Self-discharge in EDLC mainly arises due to three reasons: leakage-current, faradaic reactions and charge redistribution. I think due to the last point, charge redistribution, is prominent in presence of gel electrolytes.
2) In the vicinity of the solid seperator, I think charge redistribution would be less comapare to the gel ones, results quick discharge.
If the capacitor is kept at rated voltage (e.g. 1V ) for about >10 min or more, the charge redistribution inside electrodes should be ended. More, probably the self-discharges is coming for faradaic shuttle reactions, which are not always reversible in particular in acid enviroment. The purity of the carbon materials also influences the shuttle irreversible reactions
Using gel electrolyte should not cause more self-discharge, unless you had pressed the cell too hard so that there is a short circuit between your positrode and negatrode.
Gel electrolyte needs to be "wet", i.e. contain water to form the gel. If dried, a gel electrolyte will no longer contact ions properly, depending how dry the gel is.
By the way, the electric double layer (EDL) exists mostly inside the pores of the activated carbon electrode in which liquid electrolyte is still present. However, if your gel had penetrated into the pores (e.g. you mixed the activated carbon with the gel before assemble the cell), the EDL can still form, but it may not be as effective as that of a liquid electrolyte in the pores.
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