Finding EV Battery Insulation Materials

Picture an electric vehicle exploding into flames. Nobody wants to be the guy who designed that battery. 

You’ve probably seen thermal runaway in videos; this is when a battery becomes dangerously hot and can catch fire. Luckily, modern manufacturers can reduce the odds of thermal runaway by using proper EV battery insulation materials. 

As a converter specializing in complex die cutting, Strouse frequently sources insulating materials for new EV battery designs. These are the most common types used in electric vehicles.

The EV Battery Pack: Electrical Insulation

Reliable EV battery packs use components for electrical and thermal insulation. Luckily, the necessary materials may overlap. 

• Electrical insulation: Ensures the EV battery’s electrical current does not exceed the specified voltage, preventing arcing (an unwanted electrical discharge) or system failure. 
• Thermal insulation: Controls heat distribution within cells and modules to prevent overheating and, in worst-case scenarios, mitigate the effects of thermal runaway. 

Thermal Management for Improved Battery Systems

Thermal insulation for EV batteries controls the flow of heat within the battery to prevent short circuits (unwanted electrical paths). It protects the individual components within the battery pack from damage caused by rough movement, such as collisions.

Even minor scrapes on an EV battery can lead to thermal runaway propagation over time. When thermal runaway is confined to the modules, the cost of replacing an EV battery can exceed $15,000. 

Because electric vehicle battery failures are hazardous, insulating the space between modules and cells and securing the battery to the vehicle are critical components of any design. 

EV BATTERY PACKS — AREAS OF INSULATION

Every EV battery design is unique, but many use similar insulation methods.

Insulated areas include:

• EV battery cell-to-cell insulation
• Lid or casing
• Between layers

Common Materials Used to Insulate EV Batteries

The following examples provide an overview of insulation and shock-absorption materials to consider. Designs may benefit from alternative materials based on specific application needs.

1. SILICONE 

Silicone can protect your EV battery design by insulating individual cells from heat or conducting it to other parts of the battery.

1a. PROS

• Increase battery safety without adding weight or stress to surrounding components.
• Silicone braces components against vibration or sudden movement damage.
  
  

1b. CONS

• Silicone struggles to adhere to other materials that aren’t itself. 
  • If you’re designing a silicone adhesive thermal gap pad, you may need to choose a specialized adhesive for double-sided attachment to non-silicone materials.
• Silicone is often among the more expensive choices.
  
  

2. CERAMIC

When combined with silicone and other polymers, ceramic creates a highly heat-resistant combination. 

2a. PROS

• • Technical ceramics are a well-known solution to thermal conductivity due to their strong heat dissipation abilities (ideal for an EV cooling system).
  • They can sustain high temperatures for long periods without exceeding their limit (to prevent thermal runaway). 
    
    

2b. CONS

• • Ceramic material takes longer to heat up.
    • • However, it can help reduce the risk of thermal runaway by encapsulating and dissipating the battery's heat, allowing the unit to operate at a consistent temperature.

3. MICA

Mica is a cost-efficient choice for thermal runaway protection, making it a popular choice for EVs. 

3a. PROS

• • Often considered to be one of the less-expensive options for EV thermal insulation with wide temperature ranges.
  •  Forms highly effective dielectric barriers within the battery pack.
    
    

3b. CONS

• • Mica’s texture can be challenging to adhere to, and requires adhesive expertise. 

4. POLYIMIDE (KAPTON)

Polyimide film (often known by the brand name Kapton) is commonly used for EV electrical and thermal insulation. 

4a. PROS

• • Polyimide offers high thermal and dielectric resistance. 
  • It’s very durable and has high tensile strength. 
    
    

4b. CONS

• • It could be more expensive than other standard materials. 

Adhering EV Battery Components with Tape

EV manufacturers use specialized tapes that can bond EV battery cell insulation components by sealing cells, layers, or lids to help regulate the internal temperature. Examples of lightweight adhesive materials include: 

• Flame-retardant tapes
• Dielectric tapes
• Structural bonding adhesives
  
  

Building EV Insulation Solutions

The best insulation solution will depend on your battery’s design and application, so while we can recommend general materials, you should reach out to your manufacturer for specific material sourcing recommendations. 

Based on your design’s specifications, our team will help you find the most suitable options for your project. 

Of course, all development processes involve testing new, complex material designs to discover the most efficient method for creating EV batteries. If you need suitable materials or testing design adjustments, contact Strouse to test and prototype your EV battery adhesives. 

Originally published: July 11, 2023