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Polarization curve in battery module
Posted Sep 21, 2016, 2:50 p.m. EDT Battery Design, Chemical Reaction Engineering Version 5.2a 7 Replies
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This is the most basic question and I think here is where I should start. I am trying to simulate a 2D flow battery module and am applying the primary current distribution physics to it. I have prescribed the electrical conductivity for the membrane and the two electrodes. I have also applied the electrical ground on the anode electrode and electrical potential of 0.95 V on the cathode electrode. After conducting a stationary study, I am trying to get a polarization curve (i.e. voltage vs current density) in the result. I know that only the ohmic loses will be considered now. But I am not able to get the polarization curve.
Can someone help me and tell me how do I get this basic polarization curve for a applied voltage?
Also find attached the basic model.
Thank you for your help in advance.
Can someone help me and tell me how do I get this basic polarization curve for a applied voltage?
Also find attached the basic model.
Thank you for your help in advance.
Attachments:
7 Replies Last Post Sep 23, 2016, 8:25 a.m. EDT
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Posted:
8 years ago
Simple.
Set the potential to Vcell-Vpot and subsequently use a parameter sweep on the Vpol from 0.01 up to the value you want (0.5 for example, because at lower value of voltage you have concentration losses).
I hope this will help you
Set the potential to Vcell-Vpot and subsequently use a parameter sweep on the Vpol from 0.01 up to the value you want (0.5 for example, because at lower value of voltage you have concentration losses).
I hope this will help you
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Posted:
8 years ago
Thanks Daniel for the reply. But what will be the average current density expression in the probe? Before I give a parametric sweep I need to understand what exactly goes into the X axis and Y axis. X-axis: average current density which is defined as a probe in definitions (Is it phil or phis?) and Y axis is cell voltage (V_cell)
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Posted:
8 years ago
Hi,
1) x_axis ----- average current density measured with a probe on the boundary (pay attention because you can set the siec.llz ,if I rember well, with the electrolyte but generally for an electrochemical system the average current density at the electrolyte interface is different from that measured at the electrode surface as Goodenough teach). Try yourself.
2)y_axis ------ here obviously you will have Vcell (phis). NOT phil.
Rember that phil is the electrolyte potential, different from the physical one. Look at the doc to understand better.
1) x_axis ----- average current density measured with a probe on the boundary (pay attention because you can set the siec.llz ,if I rember well, with the electrolyte but generally for an electrochemical system the average current density at the electrolyte interface is different from that measured at the electrode surface as Goodenough teach). Try yourself.
2)y_axis ------ here obviously you will have Vcell (phis). NOT phil.
Rember that phil is the electrolyte potential, different from the physical one. Look at the doc to understand better.
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Posted:
8 years ago
Hey Daniel,
Where do you think I should apply the probe for current density? I am doing everything I can but just not able to get the polarization curve...I am looking to get the curve for discharge by giving the cell voltage below the OCV i.e. the equilibrium potential of cathode.
Can you look into the model attached and let me know what is going wrong with it?
Where do you think I should apply the probe for current density? I am doing everything I can but just not able to get the polarization curve...I am looking to get the curve for discharge by giving the cell voltage below the OCV i.e. the equilibrium potential of cathode.
Can you look into the model attached and let me know what is going wrong with it?
Attachments:
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Posted:
8 years ago
Sorry I can't open because it was created with a new version.
Open the file where I draw in Paint a conceptual scheme where you should place your probes.
Open the file where I draw in Paint a conceptual scheme where you should place your probes.
Attachments:
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Posted:
8 years ago
Thank you so much Daniel. It worked like a charm. I understood exactly whats happening in simulation now. Next I tried to apply the secondary current distribution physics to the same model and used the Butler volmer equation to describe the over potential of the electrodes. But again I have problem now with simulating it. It shows that the maximum iteration is reached and the solution did not converge.
As per my knowledge, the simulation should calculate the loss of current due to the overpotential and add it to the losses it found out from the primary current distribution. In the simplest way possible, Is my idea right?
Also, do you have any idea how do I go forward with this? how can I implement the secondary current distribution to the model?
As per my knowledge, the simulation should calculate the loss of current due to the overpotential and add it to the losses it found out from the primary current distribution. In the simplest way possible, Is my idea right?
Also, do you have any idea how do I go forward with this? how can I implement the secondary current distribution to the model?
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Posted:
8 years ago
Hi,
I'm pleased for the result. The problem could be resolved by increasing the number of iterations performed by comsol. Tipically the value is around 400 by default and you could increase up to 600 in the solver but from direct experience sometimes the problems are related to a bad definitions of BC or irrealistic values.
You should describe better your battery because for every application there are a lot of parameters to set.
It is a PEM?SOFC?MCFC? or other? Porous or non porous electrode???
Remember that the secondary module introduce the butler-volmer relation which is not easy to apply due to the value of transfer coeff., active surface area and so on.
For example try to use the values proposed by Costamagna for one-step reaction.
I'm pleased for the result. The problem could be resolved by increasing the number of iterations performed by comsol. Tipically the value is around 400 by default and you could increase up to 600 in the solver but from direct experience sometimes the problems are related to a bad definitions of BC or irrealistic values.
You should describe better your battery because for every application there are a lot of parameters to set.
It is a PEM?SOFC?MCFC? or other? Porous or non porous electrode???
Remember that the secondary module introduce the butler-volmer relation which is not easy to apply due to the value of transfer coeff., active surface area and so on.
For example try to use the values proposed by Costamagna for one-step reaction.