Ni-based layered double hydroxides (LDHs) with high theoretical capacity are appealing electrode candidates for electrochromic supercapacitors (ECSCs). However, the development of LDH-based ECSCs has been comparatively slow, largely because electrochromic performance—particularly cycling durability—has not been well established in LDH electrodes. Here, we report a NiCo-LDH nanosheet film that concurrently delivers robust electrochromism and efficient charge storage, enabled by chemical bath deposition (CBD) directly on substrate. Benefiting from a nanosheet-assembled porous architecture with accessible ion-transport pathways and abundant redox-active sites, the optimized NiCo-LDH film achieves broadband optical modulation (ΔT = 57.2/69.1 % at 550/950 nm), high coloration efficiency (92.3/71.1 cm²·C^-1), fast switching, and excellent electrochromic durability (95.8/80.3 % optical retention after 10,000 cycles), together with an areal capacitance of 58.0 mF·cm^-2 and 76.3% capacitance retention after 5,000 cycles. The assembled ECSC exhibits outstanding electrochromic and energy-storage performance, and further demonstrates practical functionalities including a color-indicated state of charge, the ability to power a bulb, and reduced interior temperature under simulated sunlight. These results establish NiCo-LDH films as high-performance bifunctional electrodes with scalability potential, providing a practical pathway toward electrochromic energy-storage windows for energy-efficient and intelligent buildings.

Electrochromic supercapacitors; NiCo layered double hydroxides (NiCo-LDHs); Chemical bath deposition; Nanosheet films; Cycling stability