Zn‐Electrochromic Device with Hierarchical Aerogel and Phase‐Change Material Enables Dynamic Infrared Camouflage at Extreme Temperatures

ABSTRACT Effective infrared camouflage is critical for military platforms operating in thermally extreme environments, such as high‐speed aircraft skins, armored vehicle surfaces, engine external parts, where surface temperatures can exceed 200°C. Conventional infrared camouflage systems, primarily based on liquid‐electrolyte electrochromic devices, fail under extreme heat due to the thermal instability of liquid electrolytes. Here, we overcome this limitation by developing a solid‐state, sandwich‐structured device that combines a Zn 2+ ‐based electrochromic layer with two thermally protective components: an ultralow‐conductivity polyimide aerogel (29.7 mW m −1 K −1 ) and a high‐enthalpy polyimide/polyethylene glycol phase‐change composite (150.1 J g −1 ). This integrated design achieves dynamic infrared modulation with emissivity contrasts of 0.63 (3–5 µm bands) and 0.71 (8–14 µm bands), while maintaining stable operation at 250°C and surviving short‐term exposure to 300°C. The system decouples optical control from thermal degradation, a key advance over existing approaches, facilitating real‐time signature adaptation on high‐temperature military platforms. Rapid switching (<10 s), near‐zero static power consumption in bistable states, and reversibility over thousands of cycles further support its practical deployment. By unifying electrochromic tuning, thermal insulation, and latent heat buffering in a single architecture, our work opens a new route toward intelligent thermal management in extreme conditions.