Thermal Runaway: Can Your Lithium-ion Battery Cover Plate Withstand It

According to the Ministry of Emergency Management, China reported 42 lithium-ion battery thermal runaway accidents in H1 2025, 70% involving battery pack structural damage. A lithium-ion battery cover plate is the first line of defense against thermal runaway-its performance directly affects safety. This article explores its thermal resistance requirements, material selection, structural design, application scenarios, and Xiamen APOLLO's solutions.

 

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1. High-Temperature Tolerance​

An aluminum battery cover uses 6061-T6 aluminum alloy, which maintains structural stability at 250-300℃. During thermal runaway, it won't melt immediately, buying 5-8 minutes for emergency cooling systems to activate.​

 

2. Impact Resistance Under Thermal Stress​

The cover plate must withstand 50-80kN impact force when battery internal pressure rises to 3MPa (a common thermal runaway scenario). It prevents fragments from exploding outward and damaging nearby components.​

 

3. Sealing Integrity Maintenance​

The cover plate's sealing gasket (made of silicone rubber with high-temperature resistance) must stay intact at 200℃. It stops electrolyte leakage during initial thermal runaway, avoiding secondary fire risks.

 

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1. 6061-T6 aluminum alloy: Ideal for power battery cover plate. It has a melting point of 605℃ and good formability, balancing cost and thermal resistance. It's widely used in passenger EV battery packs.​

 

2. 304 stainless steel: Suitable for prismatic lithium battery annexe. It resists corrosion from leaked electrolytes during thermal runaway, but its higher density (7.93g/cm³) adds 10-15% to battery pack weight.​

 

3. Aluminum-composite material: Combines aluminum alloy's light weight and ceramic's high-temperature resistance. It tolerates 400℃ but costs 30% more than pure aluminum, used in high-end energy storage batteries.

 

 

1. Pressure Relief Valve Layout​

Add 2-3 pressure relief valves on the power battery cover plate. Each valve opens at 1.5-2MPa (lower than battery explosion pressure), releasing internal gas to reduce explosion risks during thermal runaway.​

 

2. Reinforced Edge Structure​

Thicken the cover plate's edge by 1.5-2mm (from 1mm to 2.5-3mm). This strengthens the connection with the battery shell, preventing the cover from detaching when internal pressure surges.​

 

3. Heat Insulation Layer Addition​

Bond a 0.5mm-thick ceramic fiber layer to the cover plate's inner surface. It reduces heat transfer to the external environment by 40%, protecting nearby electrical components from high-temperature damage.

 

 

Anti-thermal runaway battery cover plates are widely used in key lithium-ion battery fields. In passenger EVs (e.g., BYD Han), the lithium-ion battery cover plate works with battery management systems to trigger pressure relief within 3 seconds of thermal runaway. In household energy storage systems, the prismatic lithium battery annexe resists long-term high temperatures (60-80℃) during charging, reducing thermal runaway risks. In commercial electric buses, the aluminum battery cover withstands frequent vibration and temperature changes, ensuring long-term safety. These scenarios verify the cover plate's critical role in thermal runaway protection.

 

 

Xiamen APOLLO's lithium-ion battery cover plate uses 99.8% high-purity 6061-T6 aluminum alloy (higher than industry's 99.5% purity), which improves high-temperature stability by 15%. Our battery cover plate undergoes 4-step quality checks (high-temperature resistance, impact resistance, sealing, pressure relief) - stricter than industry's 3-step checks - and meets IATF 16949 and UL standards.​

 

We offer flexible custom services: adjust the thickness (1-3mm) and pressure relief valve quantity of prismatic lithium battery annexe according to customers' battery models (EV, energy storage). Our global sea-land-air logistics delivers to European ports in 18-25 days, North American ports in 15-22 days, and Southeast Asia in 5-10 days. Our after-sales team provides 24-hour technical support, helping customers solve thermal runaway protection matching issues for battery packs.