Advanced Ultra-Pressure-Resistant Three-Phase Composite Insulation: Halting Thermal Runaway in Lithium-Ion Batteries

Abstract

Thermal runaway propagation (TRP) remains a critical barrier to the widespread adoption of lithium-ion batteries (LIBs). This study presents a novel composited insulation material that integrates nanofiber aerogel, particle aerogel, and robust microspheres to effectively mitigate TRP. Flexible mullite nanofibers (MNFs) are synthesized via a sol-gel method combined with electrospinning, with systematic investigations of the effects of aluminum-silicon ratio, spinning parameters, and polymer concentration on their properties. The resulting MNF mats exhibit ultralow thermal conductivity (0.0241 W/(m·K)) and exceptional thermal stability (-196°C to 1300°C). To further enhance the composite properties, hollow glass microspheres provide a robust mechanical support framework, achieving a compressive strength of 1.45 MPa, while specially modified aerogel particles significantly improve thermal insulation performance. Results show that increasing MNF content enhances mechanical strength and initially improves but later reduces thermal insulation performance. Tests on battery modules reveal that a 1 mm thick insulation material extends the average TRP time from 48.5 s to 1046 s, reducing the heat transferred to the adjacent battery from 198.34 kJ to 85.52 kJ. Remarkably, a 2 mm thick insulation layer completely blocks TRP, achieving a maximum temperature differential of 634.2°C between the front and back batteries while lowering heat transfer to 59.71 kJ. This study overcomes the longstanding trade-off between mechanical performance and thermal insulation in conventional materials, presenting a scalable and effective design strategy for advanced insulation materials with broad application potential in LIBs.