Electrode Engineering for High‐Durability Variable‐Emissivity Devices Based on Reversible Copper Electrodeposition

Abstract Variable emissivity devices enable dynamic infrared emissivity modulation for thermal camouflage, energy‐efficient architecture, spacecraft thermal control, and wearable thermoregulators. While reversible metal electrodeposition allows remarkable spectral modulation via controlled metal deposition/dissolution, electrode degradation‐induced cycling instability hinders practical application. Ultra‐thin Ir‐based electrode strategy is developed to enhance durability of reversible copper electrodeposition variable‐emissivity device. The Ir‐electrode‐enabled devices exhibit merely 11% degradation in radiative temperature variation after 8000 cycles and 23% attenuation in emissivity modulation after 6000 cycles, substantially outperforming Pt‐based counterparts (54% attenuation after 5000 cycles). This stability stems from Ir's inherent chemical inertness, superior conductivity, and mechanical robustness, which collectively suppress stress‐induced cracking, electrolyte corrosion, and electrochemical oxidation. Ir‐Au grid composite electrode ensures homogeneous deposition/dissolution, maintaining performance in large‐area rigid and flexible devices (>3000 cycles on 10 × 10 cm 2 rigid Si, >1000 cycles on 8 × 8 cm 2 flexible polyamide). Integration of Cr 2 O 3 optical interference layer with Ir electrode on BaF 2 enables dual‐band modulation (visible coloration and 3–14 µm infrared wavelength, emissivity modulation range Δε = 0.56) with stability exceeding 10 000 cycles. The Ir‐based electrode engineering exhibits enhanced stability, scalable manufacturability, compliant substrate integration, and color‐compatible operation, providing pivotal implications for thermal regulation systems, IR stealth applications, and advanced display technology.