Recent Progress of Vanadium Oxide and its Hybrid Composites-Based Electrochromic Supercapacitors: An Advanced Future Energy Storage Technology

Supercapacitors with integrated electrochromic functionality, capable of changing color in response to stored energy levels, represent a promising and emerging technology. These multifunctional devices offer simultaneous energy storage and real-time visual feedback through dynamic color modulation, making them particularly appealing for modern digital applications. When integrated into smart windows, they can contribute to energy savings by reducing the need for artificial heating and cooling. The selection of electrode materials is critical for the practical implementation of such devices in everyday applications. Among various candidates, vanadium oxide-based materials garner significant attention due to their unique optical, electrical, magnetic, and optoelectronic properties. Unlike conventional electrochromic materials such as tungsten oxide, vanadium oxide exhibits a broader range of color changes, including red, green, and gray, under different applied voltages. It also demonstrates excellent performance in energy storage systems, including batteries and supercapacitors. This review presents the fundamentals, challenges, recent advances, and future prospects of green energy technologies, with a particular focus on vanadium oxide-based electrochromic energy storage devices.