Cyclotriphosphonitrile-Based Electroactive Flame-Retardant Polymers for Electrochromic/Supercapacitor Devices

To mitigate the thermal runaway issue and thereby enhance the safety of electrochemical energy storage devices, designing electro-active materials with intrinsic flame-retardant and thermal insulation functions is considered an effective way. Herein, we propose an innovative molecular design strategy that amalgamated the cyclotriphosphonitrile derivative HCTP-BTDPBr with a conjugated polymer framework to construct intrinsic flame-retardant electro-active materials serving as dual function electrochromic/supercapacitor applications. Two series of donor–acceptor type copolymers, namely, PrOEG-BTD x -CTP y and PrOC 12 -BTD x -CTP y, were prepared by carefully modulating the ratio of HCTP-BTDPBr in the whole polymers. Systematic characterization of the electrochemical and flame-retardant performance revealed that PrOEG-BTD 0.82 -CTP 0.18, PrOC 12 -BTD 0.46 -CTP 0.54, and PrOC 12 -CTP showed obvious flame-retardant effects with the ignition times of 120, 108, and 80 s alongside heat release rates of 41.9, 27.5, and 31 KW m –2 g –1, respectively. The high specific capacitance of 87.34 mF cm –2 (at 0.1 mA cm –2 ) was obtained from PrOEG-BTD 0.82 -CTP 0.18 . Meanwhile, those three copolymers showed excellent electrochromic performance with multiple color changes between blue/transparent, purple/gray, and red-orange/grass green and impressive coloration efficiencies of 258, 158, and 172 cm 2 C 1–, respectively. Thus, we believe this molecular design strategy has great potential to improve the safety of electrochemical energy storage devices.