I tried dip coating copper and Al substrates which act like current collector. I used 1M Na2SO4 as electrolyte in a 3 cell setup. I purge N on the surface of the electrolyte during CV and purge through electrolyte before start. But still I don't see any rectangular form of CV. (I see tilted rectangle)
I had tried before with Graphene on copper, even that time, we didn't see rectangular curves.
What might be wrong?
What scanrate did you apply? At very high scanrates the shape of the CV might distort into a tilted rectangle as you described it. Also the conductivity of your coated electrode material can influence the shape of the CV a lot if you produce a rather thick coating.
Thanks Xu Xiao ! I don't know why EIS is negative.... something not right?
Try H2SO4 at 4 mol/L, for increasing significantly the conductivity of the electrolyte, and a low scan rate, 1 or 2 mV/s, for giving more time to ions to diffuse inside the porosity. You can see some papers about CV of carbon gels in my RG profile. The curves should be more rectangular, but perfect rectangular shape is just the theory for a perfect capacitor (i.e. not taking into account other effects, always present).
Alain
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