amongs these 5 samples in the image attached below
which one is having the least resistance and how do we say interpret that. i wanted to know how can we interpret the eis graph
The Nyquist plots you've shown have very distinct shapes. These shapes are indicators of the cell's electrochemical reactions.
The strongest feature in all the measurements is the long straight line going up the graph. Only one of them (P5) is at a 45-degree angle, the rest are steeper than that. P5 has a diffusion characteristic which is modelled by a Warburg element. The others (P1-P4) are best modelled with a capacitor (specifically the constant phase element (CPE))
Regarding the resistance you asked, this can be found from the intercepts with the x-axis (real resistance values). P2 is the only one with a clear semicircle. The left-hand intercept of the semicircle (which is at higher frequency) is the high frequency resistance AKA solution resistance (Rs). This is the resistance attributed to the cell materials. P5 is strange because when you extrapolate its left handed intercept, you get a negative resistance value. You may want to redo the wiring for that sample to avoid inductive effects.
To get the reaction resistances, you have to consider the diameter of the semicircle (right hand intercept minus left hand intercept). This resistance is called the charge-transfer resistance (Rct) because it tells you how easily the redox reaction takes place at the electrode interface. I don't see strong semi-circles for P1, P3, and P4 but that could be due to the scale of the figure
Your question of which has the least resistance in the simplest terms would be the one that has the smallest right hand intercept value (total resistance Rs + Rct)
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