Electrochromic Asymmetric Supercapacitor Windows Enable Direct Determination of Energy Status by the Naked Eye

Abstract

Because of the popularity of smart electronics, multifunctional energy storage devices, especially electrochromic supercapacitors (SCs), have attracted tremendous research interest. Herein, a solid-state electrochromic asymmetric SC (ASC) window is designed and fabricated by introducing WO and polyaniline as the negative and positive electrodes, respectively. The two complementary materials contribute to the outstanding electrochemical and electrochromic performances of the fabricated device. With an operating voltage window of 1.4 V and an areal capacitance of 28.3 mF cm, the electrochromic devices show a high energy density of 7.7 × 10 mW h cm. Meanwhile, they exhibit an obvious and reversible color transition between light green (uncharged state) and dark blue (charged state), with an optical transmittance change between 55 and 12% at a wavelength of 633 nm. Hence, the energy storage level of the ASC is directly related to its color and can be determined by the naked eye, which means it can be incorporated with other energy cells to visual display their energy status. Particularly, a self-powered and color-indicated system is achieved by combining the smart windows with commercial solar cell panels. We believe that the novel electrochromic ASC windows will have great potential application for both smart electronics and smart buildings.

Semitransparent Energy‐Storing Functional Photovoltaics Monolithically Integrated with Electrochromic Supercapacitors

“…Namely, the transmittance of the ECS was decreased (namely, colored) as charging and the higher transmittance was observed (i.e., bleached) when discharged. This feature of displaying real‐time storage level in color is one important characteristic of ECSs . Furthermore, we conducted coloration/bleaching and charging/discharging cyclic tests for the ECSs.…”

“…The capacitive performance of the ECS in this work was compared to those of previously reported ECSs (see Table 1). [25,[31][32][33][34] Although a direct comparison is not fair because there were no reports on two-terminal ECSs using viologens, our ECSs compared favorably to those based on EC conducting polymers or metal oxide.…”

A Wearable Second Skin‐Like Multifunctional Supercapacitor with Vertical Gold Nanowires and Electrochromic Polyaniline

“…[38,39] As shown in Figure 5e, under non-charged states, both electrodes showed color green (middle inset photograph). [38,39] As shown in Figure 5e, under non-charged states, both electrodes showed color green (middle inset photograph).…”

“…[11][12][13][14][15][16] For www.advmattechnol.de that reversibly change its colors between green and blue during redox reactions. [38][39][40][41] Here, we report on a wearable second skin-like multifunctional supercapacitor with self-assembled vertical gold nanowires (v-AuNWs) and electrochromic PANI. In comparison to traditional synthesis of gold-based conductive film such as evaporation, sputtering, or other gilding methods, [42] v-AuNW films offer the advantages of high softness and stretchability that retain integrity under severe deformations, firm attachment to the substrates with high electroactive surface area [43,44] -the two key requirements for current collectors in skin-like ultrathin supercapacitors.…”

In Situ Monitoring Small Energy Storage Change of Electrochromic Supercapacitors via Perovskite Photodetectors

“…Feng's group utilized exfoliated graphene/V 2 O 5 as the active material of micro supercapacitors to judge its charge‐discharge state via its visible color . We also developed an asymmetric electrochromic supercapacitor window based on polyaniline (PANI) and WO 3 , whose energy status can be clearly identified by naked eyes . However, the precise charge state seems hard to be obtained only through visible color, and it is also not convenient to analyze the optical state at any time.…”