Fire-extinguishing microcapsules are self-responsive, passive materials that store extinguishing agents inside thermally responsive shells. In confined battery systems, they can quickly suppress early fires caused by thermal runaway and slow further escalation before external firefighting systems are activated. In this study, two types of microcapsules, PFH@PRS and PFH/7100@PRS, were produced by microfluidic technology. They contained perfluorohexanone (PFH) and a PFH/HFE-7100 composite core, respectively. Their morphology, pyrolysis behavior, and fire-extinguishing performance were systematically evaluated. Results show that PFH@PRS has a lower initial decomposition temperature and greater activation-energy variation, making it more suitable for rapid low-temperature triggering in the early stage of thermal runaway. By contrast, PFH/7100@PRS has a higher trigger temperature and a smoother release after activation, helping maintain extinguishing-agent concentration for longer periods. Shelf-life predictions indicate that both microcapsules can be stored effectively for more than two years at 25 °C. Fire tests show that PFH@PRS is better for rapid short-range suppression, while PFH/7100@PRS can extend the effective suppression distance and perform better in higher-temperature environments. Tests on lithium-ion batteries further confirm that both types can delay thermal runaway, reduce thermal hazards, and influence smoke emission. Their complementary trigger temperatures, release behaviors, and spatial coverage provide a useful basis for designing layered, synergistic passive protection systems.
Gao et al. (Fri,) studied this question.