Flame Retardant Silicone Foam Composites with Long-term Heat Resistance for Sodium-ion Battery Thermal Runaway Protections

Sodium-ion batteries are prone to thermal runaway due to metal dendrite growth and structural stability defects, posing safety hazards. This study proposes a multi-component synergistic flame retardant and ceramization strategy, preparing a PDMS-based foam composite by introducing multi-component synergistic fillers. The material exhibits excellent comprehensive properties: after continuous burning at 1100°C for 60 minutes, the backside temperature only rises to 200°C, forming a dense ceramic layer that effectively blocks heat and oxygen transfer. The material exhibits low thermal conductivity, thereby demonstrating superior thermal insulation performance. The compression modulus is 25 kPa, and it can withstand 1000 cycles of 60% strain compression without significant stress decay, highlighting its excellent mechanical flexibility. Cone calorimetry tests show that its peak heat release rate (PHRR) is reduced by 41% compared to pure PDMS, total heat release (THR) is decreased by 27.7%, and total smoke production (TSP) is reduced by 66.9%, indicating excellent flame retardant and fireproof performance. Microscopic analysis reveals that multi-component fillers synergistically react at high temperatures to form a triple protection mechanism of "glass phase-crystalline phase-porous structure". This material provides a new solution for thermal runaway protection of sodium-ion batteries and has broad application prospects in energy storage power stations, new energy vehicles, and other fields.