Chitosan-based films with excellent flame retardancy and highly sensitive fire response for application in self-powered dual fire-alarm systems.

The widespread use of flammable building materials severely threatens residential safety. Additionally, traditional fire-alarm systems may fail in complex fire environments due to power disruptions. It is crucial to enhance the flame retardancy of material while establishing effective fire detection and early warning systems. This study prepared a chitosan/gelatin (CG) and LiBr-modified CG (CG-LiBr) composite film using an environmentally friendly water evaporation method. We coated the CG-LiBr film with polytetrafluoroethylene (PTFE), thus a flame-retardant and conductive PTFE-coated film-based triboelectric nanogenerator (PF-TENG) was developed. Notably, the CG-LiBr film exhibits outstanding alarm capabilities, with response times of 0.41 s at 100 °C and 0.4 s under flame attack. Compared to the initial CG, CG-LiBr shows a 24.4 % increase in char residue and a 62.1 % reduction in peak heat release rate. Furthermore, PF-TENG demonstrates excellent voltage output, achieving up to 60.8 V at a vertical contact-separation frequency of 5 Hz. Integrating CG-LiBr's exceptional dual-alarm function into fire protection suits and building materials, along with the development of a fire-alarm system featuring remote signal transmission capabilities, holds considerable promise for enhancing fire safety and developing intelligent early warning systems.