Smart Energy Storage: WO NW/TiCT Composite-Enabled All Solid State Flexible Electrochromic Supercapacitors.

Developing a highly efficient electrochromic energy storage device with sufficient color fluctuation and significant electrochemical performance is highly desirable for practical energy-saving applications. Here, to achieve a highly stable material with a large electrochemical storage capacity, a WO NW/TiCT composite has been fabricated and deposited on a pre-assembled Ag and WO NW conductive network by Langmuir-Blodgett technique. The resulting hybrid electrode composed of 15 layers of WO NW/TiCT composite exhibits an areal capacitance of 125 mF cm, with a fast and reversible switching response. An optical modulation of 98.2% can be maintained at a current density of 5 mA cm. Using this electrode, a bifunctional symmetric electrochromic supercapacitor device having an energy density of 10.26 µWh cm and a power density of 0.605 mW cm is fabricated, with high capacity retention and full columbic efficiency over 4000 charge-discharge cycles. Meanwhile, the device displays remarkable electrochromic characteristics, including fast switching time (5 s for coloring and 7 s for bleaching), and a significant coloration efficiency of 116 cm C with good optical modulation stability. In addition, the device exhibits significant mechanical flexibility and fast switching while being stable over 100 bending cycles, which is promising for real-world applications.