Research on the cyclic stability of infrared emissivity electroinduction control devices based on CNT films

Carbon nanotube(CNT)thin films have been found to possess excellent infrared surface emissivity electromodulation functions, exhibiting great potential in fields such as infrared camouflage and intelligent thermal control of spacecraft. The cycling stability of electrochromic devices based on CNT thin films is crucial for device applications, yet the underlying physical mechanisms affecting their stability have received limited attention. In this study, a sandwich structure electroinduced infrared emissivity dynamic control device was constructed using multi-walled CNT thin films, porous membranes, and ionic liquids. The surface emissivity control range reached an exceptional dynamic emissivity control performance of 0.60, and the fastest control response speed achieved 0.20 seconds. Further research focused on the cyclic stability of the device and its physical roots. The research revealed that the ordered structure of CNT films was severely damaged after electromodulation exceeded 200 cycles, leading to the loss of infrared emissivity modulation performance and eventual complete failure. The damage to the ordered CNT structure may originate from the impact stress of ionic liquids following electric field application, causing gradual disordering and agglomeration of the CNT film, resulting in slowed response speed and ultimate failure of infrared emission dynamic control. Based on the Coffin-Manson reliability equation, a formula for predicting cyclic stability is proposed and found to be consistent with experimental results. The research results indicate that an ordered porous structure facilitating conductive ion transport and storage is critical for achieving excellent electroinduced infrared emissivity. This research provides reference ideas for high-performance and highly stable electro-infrared emissivity control device design and material selection, as well as feasible methods for predicting lifespan.