Electric vehicles, or EVs, are becoming increasingly popular in the automotive industry. With their growing popularity, it is important to ensure these vehicles are as safe and efficient as possible, and one of the most dangerous aspects of EV batteries is the potential for thermal runaway.
What Is Thermal Runaway?
Thermal runaway is what occurs when an individual cell’s internal temperature rapidly and uncontrollably increases. This can cause the cell to catch fire or even explode, leading to damage to the battery and the vehicle, and putting the users’ safety at risk.
How to Mitigate Thermal Runaway
One of the better options to limit the impact of thermal runaway is to use premium insulation materials for your EV battery packs. Proper insulation prevents the heat or flame generated in one cell from propagating to another. Improving thermal runaway protection greatly reduces the cascading effect across other cells and allows for extra time for occupants of a vehicle to exit without being harmed.
Mica as a Thermal Runaway Insulator
While there are many materials that can be used for thermal runaway protection, the most popular option is mica. Mica creates a premium flame and heat barrier that can withstand the intensity of a thermal runaway event. Various thicknesses can be designed to withstand the thermal runaway event from a specific type of cell (18650, 21700, 26650, 4680, LiFePO4, pouch cells).
Mica has many benefits, including:
- High thermal stability/operating temperature
- Low thermal conductivity
- UL 94 V-0 fire resistance
- Lowest cost of any thermal runaway barrier
Mica can be used in various applications in the battery pack. Applications include cell and module barriers, insulating the inside perimeter of the battery pack, and the battery pack lid. Mica is also used as a flexible wrap on parts of the pack such as busbars and wire harnesses.
Further Advantages of Mica in Thermal Runaway Protection
High Voltage Resistance
In addition to its capabilities as a flame and thermal runaway barrier, mica also performs very well as a dielectric barrier. Mica products are commonly used as a primary dielectric barrier in battery packs, as well as in high voltage applications, including generators, motors, and wire and cable products.
High Thermal Stability and Fire Resistance
When a cell goes into thermal runaway, the intensity of the flame and gas, plus the molten metals ejected from the cell, can erode through most thermal runaway barriers in a matter of seconds. Temperatures can reach as high as 1200℃. Mica can easily withstand the high temperatures from the gas and flame, and when designed to the correct thickness, can withstand the intensity of the cell ejecta.
High Degree of Design Flexibility
Mica provides high flexibility of design for your EV battery insulation solutions. It can be created in thin, flexible tapes and sheets that are ideal for use in curved surfaces or areas with high geometric complexity. This material can also be provided in rigid panels that can be punched into parts for specific areas within a battery pack. Options include:
- Rigid — between modules or the inside perimeter walls of the battery pack
- Flexible — inside perimeter walls of the battery pack where conformability is required
- Rigid shapes — Molded to shapes to conform to internal components of the battery pack
- Tapes — Wrappable for solutions like busbar
Sustainability and Responsibly Sourced
There is concern for the sustainability and responsible sourcing of mica. Electrolock can offer mica options that address both of these concerns. Ask us about these options for the projects you are working on.
Cost Effectiveness
Mica is the lowest cost thermal runaway barrier. It is also the most common option for this type of protection.
Want to Learn More About Mica as a Thermal Runaway Protection Solution?
If you are looking for more information about mica as a thermal runaway protection solution for your EV batteries, Electrolock is here to help. Our team of experts has been engineering solutions for battery, high-voltage, and thermal insulation industries since 1957. With our extensive experience, we know how to design and manufacture the EV battery thermal runaway protection solutions you need.
Contact our team today to learn more, or talk to our experts in person this spring. We will be on hand at The Battery Show South in Atlanta, April 16-17. The Electrolock team will also be exhibiting at the 2025 Battery Show – Europe in Stuttgart, Germany, from June 3-5. We will be at booth 8-D71.
