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Lithium Ion Battery, NCA/graphite, cannot apply time-dependent steps

Posted 10 oct. 2020, 03:57 UTC−4 Battery Design, Studies & Solvers Version 5.5 2 Replies

Chun Huai Hsu
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Hi,

I have a NCA/Graphite battery in my thesis project going through a charge-discharge-cycling, which includes constant current charge, constant voltage charge, rest 1, constant current discharge, and rest 2.

I followed the example https://reurl.cc/8n68rg and blogpost https://reurl.cc/Kjd5KM and configured all bounary conditions of each stage. The concatenation worked with no problem with a test on simplified model. However, I just couldn't have CV charge run right after CC charge. Please refer to the attached simplified model. Since different charging stages could not run, neither could I concat them. Could it be the step 1 & 2 makng all the issues, which are Stationary and Current Distribution Initialization.

By the way, does anyone have the detailed electrochemical properties of the batteries cathode in a Tesla Model 3? I believe they are Panasonic made, while the 90% cobalt is a bit different from the COMSOL provided 80%.

Thanks in Advance,

CH

2 Replies Last Post 17 nov. 2020, 09:01 UTC−5
Chun Huai Hsu
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Posted: 4 years ago 10 oct. 2020, 10:57 UTC−4

I've found some part of answers to this question. The reason that no further execuation of the CC to CV is that there's no solver for this operation. One solution to this is manually adding a time-dependent solver in solver configuration of the very study. However, there's too much settings by adding a solver manually, and some following the example configuration is not achievable: like enabling 2 direct slvers.

CH

I've found some part of answers to this question. The reason that no further execuation of the CC to CV is that there's no solver for this operation. One solution to this is manually adding a time-dependent solver in solver configuration of the very study. However, there's too much settings by adding a solver manually, and some following the example configuration is not achievable: like enabling 2 direct slvers. CH
Chun Huai Hsu
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Posted: 4 years ago 17 nov. 2020, 09:01 UTC−5
Updated: 4 years ago 17 nov. 2020, 09:03 UTC−5

Hi All,

I have successfully solved part of the problem, especially to get the computation run. The trick works only for natural convection, where I added a heat flux to the heat transfer module, but took off the incoming air inlet. On top of that, I have to add additionally study steps for each one of "stages" included. (which are CC charge, CV charge, R1 rest, CC discharge. and R2 rest) Each "stage" contains 4 steps in the solver configuration: 1) Compile Equations, 2) Dependent Variables, 3) Time-Dependent Solver, 4) Solution Store.

Follow the instruction of this will help: https://reurl.cc/KjorNg Also to combine them up at the end of the computation: Combine Solutions. For example, to combine CC charge and CV charge, I have to combine the solution stores of them and get a combined solution in "solution 1." For the rest, I combined the previously generated sol1 with the new sol store and so on. Please refer to the attached mph files.

For anyone interesting getting the file: https://reurl.cc/KjorNg

To get off not converging issues, you have to set the boundary conditions and initial condotions correctly. It's in the higher menu of study in the model builder. First you have to select the correct liion boundary condition, and initial condition in "values of dependent variables" section. For this, you should select the solution store you arranged in solver configurations, and properly the ending second.

Hope it will be helpful.

CH

Hi All, I have successfully solved part of the problem, especially to get the computation run. The trick works only for natural convection, where I added a heat flux to the heat transfer module, but took off the incoming air inlet. On top of that, I have to add additionally study steps for each one of "stages" included. (which are CC charge, CV charge, R1 rest, CC discharge. and R2 rest) Each "stage" contains 4 steps in the solver configuration: 1) Compile Equations, 2) Dependent Variables, 3) Time-Dependent Solver, 4) Solution Store. Follow the instruction of this will help: https://reurl.cc/KjorNg Also to combine them up at the end of the computation: Combine Solutions. For example, to combine CC charge and CV charge, I have to combine the solution stores of them and get a combined solution in "solution 1." For the rest, I combined the previously generated sol1 with the new sol store and so on. Please refer to the attached mph files. For anyone interesting getting the file: https://reurl.cc/KjorNg To get off not converging issues, you have to set the boundary conditions and initial condotions correctly. It's in the higher menu of study in the model builder. First you have to select the correct liion boundary condition, and initial condition in "values of dependent variables" section. For this, you should select the solution store you arranged in solver configurations, and properly the ending second. Hope it will be helpful. CH

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