XYRON™ G803Z Passes the UL 2596 Battery Enclosure Thermal Runaway (BETR) Test with Excellent Heat and Flame Resistance
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Asahi Kasei's high-performance resin XYRON™ G803Z has passed the BETR test (Battery Enclosure Thermal Runaway) specified in UL 2596, established by Underwriters Laboratories (UL).

What is UL 2596?

UL 2596 is an international test standard that evaluates enclosure durability — specifically, whether a battery enclosure can maintain its structural integrity under the high-temperature, high-pressure conditions generated when a lithium-ion battery (LiB) enters thermal runaway.

This result is a significant milestone that accelerates deployment across a broad range of battery applications: not only EVs, but also ESS (stationary energy storage systems), industrial equipment, and residential storage batteries.

As batteries diversify, UL 2596 raises the bar for material-level safety

Driven by decarbonization, battery applications are expanding rapidly. Beyond EVs, batteries are being adopted in backup power supplies for data centers and factories, storage systems for offices and homes, and industrial equipment such as robots and agricultural machinery.
Across these diverse applications, a common set of requirements has emerged:

Across these diverse applications, a common set of requirements has emerged:

• Shape retention under high-temperature conditions
• Resistance to rising internal pressure
• Fire propagation suppression and safety assurance during thermal runaway
• Electrical insulation and weight reduction
• Design freedom through injection molding

The UL 2596 evaluation demonstrates that XYRON™ meets these performance requirements at a high level.

Key characteristics of XYRON™ G803Z confirmed in the BETR test specified in UL 2596

In the BETR test, a representative test specified in UL 2596, XYRON™ G803Z demonstrated the following:

• Retains enclosure shape even at temperatures of approximately 750°C
• Mechanical strength to withstand 563 kPa of internal pressure
• Suppression of fire propagation caused by combustion gas leakage

These results indicate the material’s potential for use in a wide range of battery-related components, including EV battery enclosures, residential energy storage system enclosures, partition walls for industrial battery modules, and covers for backup power systems.​

The value of an injection-moldable material that passes the UL 2596 BETR test

Conventional materials that pass the BETR test rely on long-fiber reinforcement to achieve mechanical strength, which places constraints on product design. XYRON™, by contrast, can be injection molded into complex geometries.​​

• Weight reduction through metal replacement
• High-precision design with greater design freedom
• Both heat resistance and flame retardancy

These characteristics make a substantial contribution to higher battery system performance and expanded design freedom.​

Looking ahead to growth in the energy sector (developer comment)

Rui Yoshioka, XYRON Technology Development Department, Performance Plastics Division, Asahi Kasei Corporation