Dual Function Metallo-Organic Assemblies for Electrochromic-Hybrid Supercapacitors

An integrated electrochromic-hybrid supercapacitor (EHSC) is demonstrated; the device's operation (charging-discharging) is indicated by optical changes (from colored to transparent). The heart of the device is an electrochromic metallo-organic layer that functions as both the battery-type electrode and the charge indicator. The capacitive electrode is a layered composite of multiwalled carbon nanotubes (MWCNTs) and a conductive polymer (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, PEDOT:PSS). The device operates under low potentials (-0.6 to 2 V), displays high energy and power densities (approximate to 2.2 Wh kg(-1)and approximate to 2529 W kg(-1)), a high coulomb efficiency (99%), a short charging time (approximate to 2 s), and a charge retention (V-1/2) of approximate to 60 min. Stability, both in color and energy, for more than 1000 consecutive charging-discharging cycles is demonstrated. No significant changes in device temperature are indicated under the operating conditions. The EHSC is wired with a conventional circuit board to be charged and subsequently to operate a diode. The results demonstrate the potential of metallo-organic assemblies for usage in these types of supercapacitors.