Nanofilament array embedded tungsten oxide for highly efficient electrochromic supercapacitor electrodes

Abstract

The high-activity of metallic nanofilament array (NFA) embedded tungsten oxide (WO₃) bifunctional electrodes for electrochromism and electrochemical energy storage is presented. The NFA reduces charge transfer resistance and increases the electrochemically active surface area at the electrode–electrolyte interface. The NFA-embedded WO₃ electrode exhibits a specific capacity of 214 F g⁻¹ (pristine WO₃: 133 F g⁻¹) at 0.25 mA cm⁻², excellent cycling stability with ∼92% capacitance retention after 2000 cycles (pristine WO₃: ∼75% capacitance retention) and a coloration efficiency of 128 cm² C⁻¹ (pristine WO₃: 91 cm² C⁻¹) with superb optical modulation. These properties are significantly more advanced compared to the pristine WO₃ electrode and superior to previously reported WO₃-based composites and nanostructured materials.