If we apply an AC current to a conductor it creates an associated alternating magnetic field around it. That's the theory. Additionally, when a current passes through the conductor, there is some voltage drop associated with the resistance. That's the theory (Ohm's law) as well. For the calculation of the voltage drop, one can take the electrical conductivity (in S/m) from a database and calculate that resistance.

Now, what happens if we have an electrolyte instead of a solid conductor? The conductivity associated with the electrolyte is the "ionic conductivity", correct? This means that the energy is transferred through ions, instead of electrons, which makes sense. The theory looks clear, but what is confusing is... what happens with the electrons? Is the conductivity of an electrolyte a combination of both electronic conductivity and ionic conductivity?

I have found a helpful graph here:

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But this one still doesn't explain the deconvolution of the two properties for the same material. It seems like they are separated and different and have different charges, and one would expect them to be different, but when reading about electrolytes, it's many times associated with "ionic conductivity". Although, on Wikipedia, one can find this:

The electrical conductivity of a solution of an electrolyte is measured by determining the resistance of the solution between two flat or cylindrical electrodes separated by a fixed distance

Which makes me think that they are separated.

My question:

  1. Is the ionic conductivity the same as the electrical conductivity for an ionic liquid, if one wants to calculate the voltage drop or the electrical resistance?

2 Answers 2


In a normal electrolyte the ionic conductivity dominates. The motion of ions to different locations moves much more charge per unit time than the movement of electrons between molecules. They surely both happen, but the ionic conductivity dominates (in typical electrolytes).

The primary purpose of an electrode is to convert an electronic current to an ionic current. At the surface of an electrode there is an electrochemical reaction. For example, at a copper cathode electrons in the metal go to the surface and, at the surface, they combine with a copper ion to pull the ion out of solution and deposit it as additional metal on the electrode (electroplating). This results in both electrons in the metal and ions in the solution flowing towards the surface, for current flowing in to the electrode from the electrolyte.


Is the ionic conductivity the same as the electrical conductivity for an ionic liquid, if one wants to calculate the voltage drop or the electrical resistance?

No, it is not.

Conductivity can be generally described as the ease with which charge carriers move through a material as a result of an applied potential

The electrical conductivity in a solid (metal) is a function of electron mobility in the conduction band of a metal since the electrons are the charge carriers Typically, a very fast process since the electrons move rapidly through a metal.

The conductivity of a liquid aqueous based electrolyte is NOT a function the mobility of the electrons in the liquid. The electrons are not moving through the conduction band of the liquid. The electrons hitch a ride on the much slower moving ions in solution at one electrode and then move through the solution until they reach an electrode and the ions give up the electrons to create a current flow. So the charge carriers are the ions in solution, not the electrons.

While the IV behavior of a liquid electrolyte may show linear behavior over small voltage ranges, it becomes non-linear as the voltage for the hydrolysis of water is approached.

Also, the electrodes in an liquid electroyte have built in capacitive component (Gouy-Chapman layer) which gives RC behavior. AC measurements are recommended for accurate conductivity measurements.


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