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 (≈2.2 Wh kg⁻¹ and ≈2529 W kg⁻¹), a high coulomb efficiency (99%), a short charging time (≈2 s), and a charge retention (V_½) of ≈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.