High performance multi-color prussian blue/poly(indole-5-carboxylic acid) nanocomposites with multiple layer nanosphere structure for electrochromic supercapacitor application

A novel Prussian blue/poly(indole-5-carboxylic acid) (PB/P5ICA) nanocomposites with multiple layer nanosphere structure are successfully prepared. The structure and morphology of the prepared PB/P5ICA nanocomposites are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman and X-ray photoelectron spectroscopy (XPS) techniques. Due to the synergistic effect of the electrochromic properties of PB and P5ICA, the PB/P5ICA nanocomposites have good electrochromic performance and rich color changes, which can be reversibly changed among light yellow, light green, blue, and yellow-green. In addition, PB/P5ICA also shows good capacitance performance and cycle stability. The specific capacitance value reaches up to 98.12 mF cm−2 (723.48 F g−1) at the current density of 0.2 mA cm−2, which is much higher than PB and P5ICA at the same current density. A symmetric electrochromic supercapacitor device (ESD) is fabricated based on the PB/P5ICA nanocomposite. The supercapacitive properties, color changes and cycle stability of the device are also studied. The results indicate that the device has good energy storage capacity. When the current density is 0.2 mA cm−2, the specific capacitance of the device is 36.2 mF cm−2 (321.09 F g−1). Moreover, the color of the electrode material changes obviously during the charging and discharging process of the device, which can realize the visual monitoring of the device’s energy storage state. Through long-term cyclic voltammetry (CV) and galvanostatic charge and discharge (GCD) test, the device shows good cycle stability. The research is of great significance to the preparation of multifunctional energy storage materials and the application of electronic devices.