Cu-MOF-derived Cu2V2O7@C nanofilm for electrochromic properties

Electrochromism (EC) is an emerging energy conversion technology, in which vanadium pentoxide (V 2 O 5 ) is a promising material for electrochromic applications due to its excellent ionic intercalation/deintercalation properties and cathodic/anodic color-changing properties. However, its poor cycling stability and color change response rate limit its practical application. Metal-organic frameworks (MOFs) combine the rigidity and flexibility of inorganic-organic materials and can meet the requirements of EC materials such as cycle stability, electrical conductivity, and stress-interference resistance. We report here a strategy to modify V 2 O 5 with CuMOF. Cu-doped V 2 O 5 and carbon skeleton (Cu 2 V 2 O 7 @C) composites were prepared for electrochromism. In this scheme, Cu doping can facilitate lithium ion migration by broadening and stabilizing the structure of V 2 O 5 , and the distribution of the carbon skeleton can broaden the contact of the active material with the electrolyte and improve the electron conduction. Combining these merits, it exhibits excellent long-term cycle stability (the capacity retention rate reaches 91.78% after 2000 cycles), the light transmission modulation is greatly improved compared with V 2 O 5 (ΔT = 69%, doubled), and the response time is reduced by 30.43%. This study provides a new perspective for improving the light modulation ability and long-term use stability of vanadium oxide EC materials and promotes the development of MOFs materials in the field of electrochromism.