Co single-atom doped V2O5-x coupled with poly(5-formylindole) for high-performance electrochromic supercapacitor

Electrochromic supercapacitors (EC-SC), which integrate energy storage and intelligent light modulation, show broad application prospects despite being constrained by limitations such as single-color variation, sluggish color transition kinetics, and inadequate electrical conductivity. To break through this bottleneck, we simultaneously introduce Co single-atoms and oxygen vacancies (Ov) into the V 2 O 5 substrate and further modify it with poly(5-formylindole) (P5FIn), thereby greatly improving the conducting and electrochromic performance of the material. The modified P5FIn/Co-V 2 O 5-x electrochromic film has a capacitance of 291.6 mF cm −2 at a current density of 1 mA cm −2 and an optical modulation effect of 54.5 % at 800 nm, while its capacitance remains at 95 % during 10,000 charge and discharge tests. The finely tuned EC-SC has high specific capacitance (241.1 mF cm −2 ), practical power density and capacity density (1.7 W cm −2 and 133.94 mWh cm −2 ), significant optical contrast (ΔT 980 nm = 71 %), high coloration efficiency (156.4 cm 2 C −1 ), fast switching (4.2 s/4.2 s for color rendering/bleaching), and long operational stability (>3000 cycles). In this study, a synergistic structure that combines Ov, single-atoms, and conductive polymers is constructed, which leads to significant enhancements in optical response, capacitive performance, and cycling stability, and this work presents a scalable strategy for designing high-performance EC-SC devices.