Enhancing EV battery safety with superior resistance to flames and particle blasts

The Japanese technology company Asahi Kasei is introducing a new material solution for enhanced EV battery safety. A flame-retardant and highly flexible nonwoven fabric, LASTAN™ is an outstanding alternative to conventional materials for thermal runaway protection. It can be utilized in top covers, busbar protection sleeves, and other applications within the EV battery pack.

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New grade of LASTAN™ (Photo: Business Wire)

Although electric vehicles are becoming more common worldwide, battery safety is still a major concern for many car users. According to the latest “Asahi Kasei Automotive Consumer Survey,” 34% of non-EV owners in China see improved safety as a primary consideration in buying an electric vehicle. Against this background, global OEMs seek to further raise the safety of EV batteries, and the market for materials to prevent thermal runaway is expected to grow by some 15% annually from 2024 onward, with even further expansion of demand in the future (IDTechEX: “Fire Protection Materials for Electric Vehicle Batteries 2024–2034”).

In this context, there is increasing demand for materials in EV battery cover applications having excellent resistance against flames and particle blasts, as well as good electrical insulation properties. While mineral-based materials are generally used as protection against thermal runaway at present, such materials tend to be heavy and brittle. Being stiff, these materials are difficult to adapt to complex shapes, making processability an issue for automotive OEMs.

LASTAN™ is a non-mineral flame-resistant fabric made by air baking a special acrylic fiber at 200–300°C. It is characterized by high flame resistance and good electrical insulation, which are further improved by a special coating process that also augments abrasion resistance. This allows the material to provide effective protection against particle bombardment from venting gas. With these exceptional characteristics, LASTAN™ has been used for many years as an optimal material for failure prevention and safety in various industries.

Withstanding 1,300°C flames and impact of 200–500 µm particles

Even when a 1,300°C flame is applied, the temperature on the opposite side of LASTAN™ remains below 400°C. While a “limiting oxygen index” (LOI) value of 27 or higher is generally considered to indicate flame retardance, this material has an LOI value of 50 or higher. In UL94 flame retardance testing, LASTAN™ has obtained the highest rating of 5VA. No holes are formed in LASTAN™ even when it is exposed to a flame of 1,300°C for one minute.

In addition to its high flame resistance, LASTAN™ is resistant to high-pressure impact by particles of 200–500 µm. It also provides electrical insulating capacity of up to 3.5 kV at a thickness of 1 mm. LASTAN™ also features outstanding processability, being highly flexible while maintaining its performance characteristics in sheets as thin as 0.8 mm. This makes it easily processed with ordinary tools, contributing to a simplified manufacturing process.

Having integrated production of LASTAN™ currently in Japan, Asahi Kasei is considering production in the United States and other countries in the future. The company will exhibit the new LASTAN™ grade at the North American Battery Show from October 7 to 10, 2024, in Detroit, Michigan.

About Asahi Kasei

The Asahi Kasei Group contributes to life and living for people around the world. Since its founding in 1922 with ammonia and cellulose fiber businesses, Asahi Kasei has consistently grown through the proactive transformation of its business portfolio to meet the evolving needs of every age. With more than 49,000 employees worldwide, the company contributes to a sustainable society by providing solutions to the world's challenges through its three business sectors of Material, Homes, and Health Care. Its Material sector, comprised of Environmental Solutions, Mobility & Industrial, and Life Innovation, includes a wide array of products from battery separators and biodegradable textiles to engineering plastics and sound solutions. For more information, visit https://www.asahi-kasei.com/.

Asahi Kasei is also dedicated to sustainability initiatives and is contributing to reaching a carbon-neutral society by 2050. To learn more, visit https://www.asahi-kasei.com/sustainability/.

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