How to find the best settings for Cyclic voltametery test?
I know nothing about Agar or volummetry but higher scan rates ought to increase current dues the dielectric constant and how thin the material layer is without voids between conducting electrodes.
This is essentially a voltage sensitive material with polar hysteresis created by a REDOX cell voltage reaction, much like permeability is to magnetic materials which normally display H field current on the X axis orthogonal to yours.
My suggestion is to change the thickness and

also change the sweep waveform to more of a square wave with slew rate limits.( if this is permitted) If this makes it worse then you are seeing excessive ESR from galvanic resistance.

in event of the above failure, then I would suggest investigating your electrode material for better types. ( gold plated)



Ic = C dV/dt for linear dielectrics and hysteresis depends on saturation of the polar ions without voids or contaminants.
I’ll have to read up on  electrochemical impedance spectroscopy. Right now it looks a bit like a 10 Ohm resistor with asymmetric hysteresis.
Here is my simulation of your signals using a buffered bipolar Howland Current Source with a variable sweep current linear slow sweep (faster than real-time) of your signal with ideal diodes and 0.6V bipolar cells with an RC network.