High-Performance Asymmetric Electrochromic-Supercapacitor Device Based on Poly(indole-6-carboxylicacid)/TiO2 Nanocomposites.

A difunctional porous network of poly(indole-6-carboxylicacid) (PICA)/TiO2 nanocomposites is first prepared using TiO2 nanorod arrays as the scaffold. Because of the synergistic effect of PICA and TiO2, the nanocomposites show good electrochemical performance, a high specific capacitance value (23.34 mF cm-2), and excellent galvanostatic charge-discharge stability. Meanwhile, this nanocomposite can be reversibly switched (yellow, green, brown) with a high coloration efficiency (124 cm2 C-1). An asymmetric electrochromic-supercapacitor device (ESD) is also constructed using the PICA/TiO2 nanocomposites as the anode material and poly(3,4-ethylenedioxythiophene) as the cathode material. This ESD has robust cycle stability and a high specific capacitance value (9.65 mF cm-2), which can be switched from light green to dark blue. After charging, 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 applications in intelligent energy storage and other smart electronic fields.