High performance asymmetric electrochromic-supercapacitor device based on poly(indole-6-carboxylicacid)/TiO2 nanocomposite.

A difunctional porous network poly(indole-6-carboxylicacid) (PICA)/TiO2 nanocomposite is firstly prepared using TiO2 nanorod arrays as scaffold. Because of the synergistic effect of PICA and TiO2, the nanocomposite shows good electrochemical performance, high specific capacitance value (23.34 mF cm-2) and excellent galvanostatic charge and discharge stability. Meanwhile, this nanocomposite can be reversibly switched among yellow, green, brown with high coloration efficiency (124 cm2 C-1). An asymmetric electrochromic-supercapacitor device (ESD) is also constructed using PICA/TiO2 nanocomposite as anode material and poly(3,4-ethylenedioxythiophene) (PEDOT) as cathode material. This ESD has robust cycle stability and high specific capacitance value (9.65 mF cm-2), which can be switched from light green to dark blue. After charged, the device can light up a single LED for 108 s and the energy storage level can also be monitored by the corresponding color changes. This constructed ESD will have great potential application in intelligent energy storage and other smart electronics fields.