Nanofilament array embedded tungsten oxide for highly efficient electrochromic supercapacitor electrodes

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 similar to 92% capacitance retention after 2000 cycles (pristine WO3: similar to 75% capacitance retention) and a coloration efficiency of 128 cm(2) C-1 (pristine WO3: 91 cm(2) 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.