Thermoresponsive Microcapsules with Fire-Extinguishing Composites for Fire Prevention

Due to the increased demand for energy-storage devices, such as lithium-ion batteries (LIBs), for use in diverse pieces of equipment ranging from portable electronic devices to automobiles, the number of battery-related fires has increased. In particular, for LIBs, controlling the fires caused by thermal runaway after the initial ignition is difficult, making initial fire control vital. In this study, we developed fire-extinguishing composites, namely, PFMPF19, PFMPF55, and PFMPF91, for use in fire-control systems. Further, we tested their fire-extinguishing performance and compared them with existing fire-extinguishing agents (FEAs), with PFMPF55 exhibiting the best performance. Through a microencapsulation technique involving urea-formaldehyde (UF) as the shell material, we effectively encapsulated the composites, obtaining the UF-X series, where X represents FEAs. We implemented various analysis techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy, and optical imaging, to evaluate the synthesized UF-X series. Moreover, thermogravimetric analysis and differential scanning calorimetry were implemented to predict the temperature-dependent release rate of the capsule's FEAs for the UF-X series. These findings were further validated by laboratory-scale combustion tests, in which UF-PFMPF55 exhibited the shortest combustion time (19 s), highlighting its outstanding fire-suppression effect.