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Ionic current and electrostatics
Posted 4 ago 2017, 18:48 GMT-4 Low-Frequency Electromagnetics, Battery Design, Chemical Reaction Engineering, Electrochemistry Version 5.3 3 Replies
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Thanks in advance for any help that may come from the post!
I'm trying to put together a model to resolve the resulting ionic current between two Ag/AgCl electrodes at fixed potential in a KCl electrolyte. My first approach was to use the electrical currents module to determine the current since I know the conductivity of my electrolyte. However, because future iterations of the model may look at charged surfaces, nanometer scale-lengths, and electrophoretic transport, I'd like to make the model a bit more robust and determine the ionic current by looking at the flux of the ions. As a result, I've tried combining the transport of diluted species and electrostatics physics to get a ion distribution (N-P). My problem lies in that I do not know what physics is best to consume and generate chlorine ions, and therefore produce a current. With the current setup, the chlorine ions concentrate near one electrode.
I understand that there are ways to do this using an electrochemistry approach, but since I am not concerned with the actual physics of the redox reactions at the electrodes, I am hoping there is a simple solution.
Just to rephrase the overall goal: I'm hoping to measure ionic current through a salt water electrolyte, with the current being generated by two electrodes with fixed potential. By tracking ionic flux, I am hoping to have a model that also incorporates things like ionic screening and interaction with charged surfaces.
I'm trying to put together a model to resolve the resulting ionic current between two Ag/AgCl electrodes at fixed potential in a KCl electrolyte. My first approach was to use the electrical currents module to determine the current since I know the conductivity of my electrolyte. However, because future iterations of the model may look at charged surfaces, nanometer scale-lengths, and electrophoretic transport, I'd like to make the model a bit more robust and determine the ionic current by looking at the flux of the ions. As a result, I've tried combining the transport of diluted species and electrostatics physics to get a ion distribution (N-P). My problem lies in that I do not know what physics is best to consume and generate chlorine ions, and therefore produce a current. With the current setup, the chlorine ions concentrate near one electrode.
I understand that there are ways to do this using an electrochemistry approach, but since I am not concerned with the actual physics of the redox reactions at the electrodes, I am hoping there is a simple solution.
Just to rephrase the overall goal: I'm hoping to measure ionic current through a salt water electrolyte, with the current being generated by two electrodes with fixed potential. By tracking ionic flux, I am hoping to have a model that also incorporates things like ionic screening and interaction with charged surfaces.
3 Replies Last Post 9 ago 2017, 07:59 GMT-4
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Posted:
7 years ago
S A
Combining transport of dilute species with secondary current distribution would be the way to go. You cannot get away from an electro-chemical approach if you want to capture all the potential drops and eventually capture the ionic current correctly. You can use a not-so-real tafel relationship to account for the consumption of chlorine ions.
Sri.
Combining transport of dilute species with secondary current distribution would be the way to go. You cannot get away from an electro-chemical approach if you want to capture all the potential drops and eventually capture the ionic current correctly. You can use a not-so-real tafel relationship to account for the consumption of chlorine ions.
Sri.
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Posted:
7 years ago
Thanks for the reply! Unfortunately, I do not know much about the electrochemistry physics that occurs at the electrodes, but I'm willing to learn! My only concern with the approach you suggested is that things like ion screening and non-electroneutrality conditions are not taken into consideration without N-P equations also being included in the model.
Is it as simple as just combining the transport of diluted species, secondary current distributions, and N-P modules to manage the entire problem?
Is it as simple as just combining the transport of diluted species, secondary current distributions, and N-P modules to manage the entire problem?
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Posted:
7 years ago
Hi
Are you trying to model transient or steady-state phenomena?
I agree with the previous reply in that electrochemical reactions are unavoidable at the electrodes. On the anode, chlorine gas is evolving and on the cathode water is split to hydrogen gas and hydroxyl ions. Modeling this reaction contains this and that, perhaps the Tafel equation suffices.
Lasse
Are you trying to model transient or steady-state phenomena?
I agree with the previous reply in that electrochemical reactions are unavoidable at the electrodes. On the anode, chlorine gas is evolving and on the cathode water is split to hydrogen gas and hydroxyl ions. Modeling this reaction contains this and that, perhaps the Tafel equation suffices.
Lasse