Battery Impact and Thermal Runaway
Hi everybody, my name is Adam Remmel. I'm an application engineer for Ozen Engineering. Today, I'm going to give you a brief introduction on how to model structural deformation and thermal abuse of a battery using ANSYS tools.
Introduction to Battery and Thermal Runaway
Thermal runaway in batteries is caused by external abuse, such as:
- External heating
- Overcharging
- Impact (as demonstrated in this presentation)
This abuse leads to internal events, specifically exothermic reactions within the battery, causing the temperature to increase. If the heat generated by these reactions exceeds the battery's heat dissipation rate, thermal runaway occurs.
Understanding Exothermic Reactions
To model this complex process, we break it down into three main steps:
- Model the structural impact.
- Capture the physical characteristics of the damaged zone.
- Use the information for electrochemical thermal modeling.
Modeling Example
For this example, I use a six-cell battery and ANSYS Workbench LS-DYNA to model the battery being impacted by a sphere. The sphere is given an initial velocity and collides with the battery, allowing us to observe the deformation caused by the impact.
Here are the results from the simulation:
- The top right displays the displacement caused by the impact, which helps us assess the damage and its effects.
Internal Battery Reactions
In an ideal battery, there is a positive electrode, a separator, and a negative electrode. Damage to the battery can break the separator, allowing a large current to pass between the electrodes, resulting in exothermic reactions and increased temperature.
Electrochemical Thermal Simulation Steps
Once displacement damage occurs, follow these steps to simulate the electrochemical thermal behavior:
- Run the thermal abuse model with the MSMD battery model enabled in Fluent.
- Simulate until a battery stop condition is met, typically when the voltage difference between electrodes drops below a certain point.
- Turn off electric, ohmic, and short circuit heat sources, and run the thermal abuse model standalone.
- Run the thermal abuse model with a small time step.
- When thermal abuse heat source terms approach zero, increase the time step to solve for the thermal behavior of the cells.
Simulation Results
The simulation shows a temperature contour at the point of impact, where the temperature increases and heats the entire battery. Over time, the temperature decreases due to convection.
Volume-averaged temperature plots of each cell indicate temperatures reaching approximately 900 Kelvin.
Conclusion
Thank you for watching. This video is brought to you by Ozen Engineering. We use physics-based simulation to solve multidisciplinary engineering problems, specializing in FEA, CFD, and electromagnetics.
For more information, you can:
- Email us at info@ozeninc.com
- Call our office
- Visit our website at www.ozeninc.com
Hi everyone, my name is Adam Remmel. I'm an application engineer for Ozen Engineering. Today, I'm going to be giving you a brief introduction to how to model structural deformation and thermal abuse of a battery using ANSYS tools.
Let's start with a quick introduction to batteries and thermal runaway. Thermal runaway in batteries is caused by some sort of external abuse, such as external heating, overcharging, or impact.
This causes internal events, specifically exothermic reactions within the battery, which cause the temperature to increase. If the heat generation of those reactions exceeds the rate at which the battery can dissipate the heat, you lead to a thermal runaway.
Exothermic reactions are a critical part of this process. Let's break it down into three main steps: 1. Model the structural impact. 2. Capture the physical characteristics of the damaged zone. 3. Use that information for the electrochemical thermal modeling.
For this example, I have a six-cell battery. I'm using ANSYS workbench LS-Dyna to model the battery being impacted by a sphere. The sphere is given initial velocity and runs into the battery. We look at the deformation caused by that. Here are the results from the simulation.
The displacement caused by the impact is what we'll use to examine the damage and its effects. Once there's damage to the battery, this is what happens inside: in an ideal battery, you have a positive electrode, a separator, and a negative electrode.
When the battery undergoes damage, you get a break in the separator, allowing a large amount of current to pass from the positive to the negative electrode, resulting in exothermic reactions, which cause the temperature to go up.
Now, let's discuss the electrochemical thermal simulation part of this problem.
There are several steps: 1. Run the thermal abuse model with the MSMD battery model turned on in Fluent. 2. Simulate until a battery stop condition is met. 3. Turn off the electric, ohmic, and short circuit heat sources. 4. Run the thermal abuse model standalone. 5. Run the thermal abuse model with a small time step. 6. Increase the time step and solve for the thermal behavior of the cells when the thermal abuse heat source terms approach zero.
This is what the temperature contour looks like. At the point of impact, the temperature goes up, heating the entire battery. Over time, it eventually starts dropping back down due to convection. Finally, here's a plot of the volume-averaged temperatures of each cell.
The temperatures of the cells reach about 900 degrees Kelvin. Thank you for watching. This video has been brought to you by Ozen Engineering. We use physics-based simulation to solve multidisciplinary engineering problems. We specialize in FEA, CFD, and electromagnetic.
If you'd like to learn more, you can email us at [info@ozeninc.com](mailto:info@ozeninc.com), call our office phone number, or visit our website at [www.ozening.com](http://www.ozening.com).
