ITW Formex® Electrical Insulation is Ideal for Electric Vehicles

Battery systems in electric vehicles face demanding environmental, mechanical, and chemical requirements. In addition to these requirements, vehicle designers are being asked to emphasize safety and weight reduction. These demands drive their search for battery-related materials that are lightweight, inexpensive, flame retardant, and meet rigorous electrical insulation requirements. These requirements extend to the battery cover material, which must not only serve reliably as an electrical barrier, but also meet an OEM’s targets for original cost, and maintenance costs under service agreements.

While electric vehicle battery requirements are similar to those for cars with only internal combustion engines, there are some differences in these two applications. Perhaps the most striking differences are the much larger size of electric vehicle batteries, and where they are located in the car. Conventional car batteries located in the engine compartment typically use only small covers over two battery terminals. Electric vehicles typically use many batteries with their terminals strapped together to get the drive voltage and current needed for the car motor. This means the battery cover must be larger. In addition, an electric car battery system could be placed in different locations depending on vehicle design. This has implications for the shape and other requirements placed on an electric vehicle battery cover.

When ITW Formex® looked at these battery cover requirements, company engineers saw that its FORMEX™ electrical insulation material would be an ideal solution. This polypropylene sheet insulation meets the demanding requirements of electric vehicle design, and is easily formed in a wide range of sizes and shapes. This makes battery cover manufacturing highly cost efficient.

Unlike materials that need to be formed with large, expensive injection molding equipment, FORMEX is easily and economically formed into complex three-dimensional parts with a variety of inexpensive equipment and processes. These include:

• Die Cutting
• Blanking
• Scoring
• Folding/bending
• Hole punching
• Tab formation
• Joinery
• Welding
• Laminating
• Thermoforming

In addition, FORMEX is resistant to most battery chemistries, and the same electrical insulation material can be used to insulate batteries and conductors from each other.

FORMEX delivers superior performance in comparison to other battery cover materials such as aramid paper. Aramid paper absorbs significantly more moisture, is less dimensionally stable, is more expensive, and does not provide score and fold capabilities. Because FORMEX has higher dielectric strength (is a better electrical insulator), thinner product can be used to reduce weight.

References. For more information about using FORMEX to make automotive battery covers and insulators for conventional and electric vehicles, or to request samples, contact ITW Formex at www.itwformex.com/battery; click on Technical Lit to access the ITW Formex Design Guide and Product Data Brochure. You can also phone 630-315-2212, fax 630-315-2155, or send an email to info@itwformex.com; in Asia, visit www.itwelecshanghai.com.