Design of coral-like P5ICA/Ov-MoO3 composites with oxygen vacancy for electrochromic supercapacitors

Novel materials with highly synchronized electrochromic and energy storage properties are required for integrated visualization and real-time monitoring of the energy state of energy storage devices. However, developing electrochromic supercapacitor (ECSC) devices with high optical contrast, capacitive properties, and cycling stability remains a long-term challenge. Here, we propose an oxygen vacancy converts nanorods into nanoparticles design strategy to prepare a transparent film by combining poly(indole-5-carboxylic acid) (P5ICA) nanofibers with monoclinic oxygen vacancy-engineered MoO₃ (Ov-MoO₃), which greatly improving the light absorption range and pseudocapacitive performance of Ov-MoO₃. The obtained coral-like heterostructure P5ICA/Ov-MoO₃ film can work synergistically through more redox-active sites, including pronounced electrochromic performance (54.3 % optical contrast at 600 nm with coloration efficiency of 120 cm² C⁻¹), fast switching time (t_b/t_c = 3.6 s/1.2 s), high specific capacitance (575.9 mF cm⁻² at 1 mA cm⁻²) and good cycling stability (94.8 % optical modulation maintained after 3000 cycles). In addition, we further fabricate its-based ECSC to simultaneously quantify and visualize its energy storage state in real-time, which exhibits high electrochromic performance (51.1 % at 540 nm), favorable specific capacitance (358.6 mF cm⁻² at 1 mA cm⁻²), and successfully powered light emitting diodes with the stored electrical energy. The oxygen vacancies design strategy and coral-like heterostructure P5ICA/Ov-MoO₃ materials are working to broaden the application scope of ECSC composite materials and provide a feasible design strategy for next-generation smart energy storage devices.