Mechanism of the influence of thermal aging on flame-retardant microcapsulated phase-change materials for battery thermal safety

Flame-retardant composite phase-change materials (CPCMs) often face low flame-retardant efficiency and performance degradation after temperature aging owing to flame-retardant migration, limiting their use in electric vehicle battery packs and marine power systems. To address these challenges, we propose an innovative flame-retardant microencapsulated CPCM comprising ammonium polyphosphate (APP), dipentaerythritol (DPER), and melamine cyanurate (MCA) (AD@MCA) to improve battery module thermal safety. The microcapsules, prepared via in situ polymerization, enhance the flame-retardant efficiency and cycling stability of APP. This study compares the properties of CPCMs containing microencapsulated flame retardants and traditional physically blended flame retardants before and after thermal aging. Results show that the synergistic effect between MCA and DPER in the microencapsulated structure markedly improves the flame-retardant efficiency and cycling stability of APP. Furthermore, CPCMs containing microencapsulated flame retardants exhibit excellent battery thermal management performance and delay thermal runaway trigger times. This study presents a novel approach for developing multifunctional flame-retardant CPCMs for battery packs, addressing key challenges in battery thermal safety under extreme conditions.