1. Understanding Thermal Runaway

Thermal runaway in lithium-ion batteries occurs when internal heat generation exceeds the system’s capacity to dissipate it, resulting in self-accelerating temperature rise, electrolyte decomposition, and potential ignition. The phenomenon typically originates from:

• Internal short circuits: Separator rupture, contamination, or mechanical damage causing direct electrode contact.
• External abuse: Overcharging, deep discharge, high-rate operation, or physical impact.
• Material reactivity: High-nickel cathodes may release oxygen at elevated temperatures, triggering exothermic reactions with the electrolyte.

Once initiated, the process forms a positive feedback loop — heat generation → material degradation → increased heat release → temperature escalation — culminating in cell venting or combustion.

2. Managing Thermal Runaway: Engineering Approach

Mitigation requires three coordinated strategies: source control, thermal pathway optimization, and material-level protection.

2.1 Source Control

• Maintain strict manufacturing quality to avoid contamination or electrode misalignment.
• Use BMS monitoring for voltage, temperature, and impedance to detect early anomalies.
• Adopt thermally stable electrode chemistries and coatings for enhanced safety margins.

2.2 Thermal Pathway Optimization

• Ensure uniform temperature distribution via cooling channels or heat spreaders.
• Combine active cooling (liquid/air) with passive systems (PCM, heat pipes).
• Use spacing or isolation barriers to limit heat propagation between cells.

2.3 Material Protection Layer

Thermal runaway propagation can be delayed or even contained through high-performance insulation and interface materials. TOUSEN® provides proven solutions for passive protection using aerogel composites and silicone-based materials.

3. Key Protective Materials

4. Layered Application Strategy

• Layer 1 (Hot Zone): GA-60 Aerogel — high-temperature isolation near cells.
• Layer 2 (Intermediate Zone): HI-370 Silicone Foam — mechanical cushioning and heat buffering.
• Layer 3 (Peripheral Zone): TY-640 Silicone Foam — sealing and secondary insulation.

The multi-layer approach provides time delay, temperature control, and safety margins in the event of cell thermal failure.

5. Conclusion

Thermal runaway is a complex electrochemical and thermal feedback process. Effective mitigation requires a system-level design combining electronic control, optimized heat paths, and multi-layer passive protection. The TOUSEN® GA-60, HI-370, and TY-640 materials collectively enhance the resilience of EV battery systems against thermal propagation.