Balancing Electrochromic and Pseudocapacitive Properties in WO 3 -Based Electrochromic Supercapacitors via Elemental Doping

Dual-functional electrochromic supercapacitors have great application prospects, but it is difficult to balance the performance of electrochromism and pseudocapacitance. In this work, dual-functional supercapacitors with excellent electrochromic performance and enhanced specific capacitance were obtained using metal elements doping of WO 3 with core/shell nanostructures. The area-specific capacitance of the 1% Mo-doped WO 3 electrode reached 64.1 mC cm −2 at 0.5 mA cm −2 ; the 3% Nb-doped WO 3 electrode area-specific capacitance reached 51.3 mC cm −2 while optical modulation was up to 83.4% (633 nm) with a coloring efficiency of 34.8 cm 2 C −1 . The equilibrium between pseudocapacitance and electrochromism for the modification process will be helpful to guide the design of dual-functional supercapacitors. The metal-doped WO 3 -based supercapacitor was assembled to achieve a synchronized color change during electrochemical energy storage. The potential of dual-functional supercapacitors for applications such as energy management is demonstrated.