All-Climate Solid-State Flexible Electrochromic Devices Enabled by Layered Hydrated Vanadate/MXene Composite and Hydrogel Electrolyte

Hydrated vanadate possesses a large layer distance and rich vanadium redox center superior for flexible electrochromic devices (FECDs). However, the low mechanical strength and high interfacial impedance caused by the low processing temperature pose key challenges. This study presents the successful development of an all-climate solid-state FECD using a hydrate vanadate/MXene composite and hydrogel electrolyte. The integration of high-crystallinity, layer-structured V2O5·1.6H2O with two-dimensional MXene nanoflakes facilitates fast ion transfer, enabling excellent electrochromic properties with fast responses (Coloring time = 5.8 s; Bleaching time = 9.8 s), large optical modulation (64.02%), coloring efficiency, and high flexibility. The hydrogel electrolyte provides strong mechanical strength and a wide operating temperature range between −10 and 55 °C. This work signifies a critical step toward the application of FECDs in smart windows, offering a promising solution for environments requiring high flexibility and climate resilience.