Flexible Inorganic All-Solid-State Electrochromic Devices toward Visual Energy Storage and Two-Dimensional Color Tunability

Abstract

Multicolor display has gradually become a soughtafter trend for electrochromic devices due to its broadened application scope. Meanwhile, the advantages of inorganic electrochromic devices such as stable electrochemical performance and good energy storage ability also have great attraction in practical production applications. However, there are still huge challenges for inorganic electrochromic materials to achieve multicolor transformation due to their single-color hue change. Herein, we design an inorganic and multicolor electrochromic energy storage device (MEESD) exhibiting flexibility and all-solidstate merits. Prussian blue (PB) and MnO 2 , as the asymmetrical electrodes of this MEESD, show good pseudocapacitance property, matching charge capacity, and obvious color change. As a typical electrochromic device, the MEESD shows a fast response of 0.5 s and good coloration efficiency of 144.2 cm 2 /C. As an energy storage device, the MEESD presents excellent rate capability and volumetric energy/power density (84.2 mWh cm −3 /23.3 W cm −3 ). Its energy level can be visually monitored by color contrast and optical modulation. In the charging/discharging process, its color can obviously change to various degrees of yellow, green, and blue along with 40% wide optical modulation at 710 nm. Meanwhile, the stability of the MEESD in a common and humidity environment was analyzed in detail from electrochemical, optical, and energy storage aspects. This work provides feasible thoughts to design multifunctional electrochromic devices integrated with inorganic, flexible, all-solid-state, multicolor, and energy storage properties.

A highly transparent ion conducting film enabling a visual electrochromic battery

“…Both areal capacities showed a decreasing trend as the current density increased due to insufficient reaction at the large current density. 47 Meanwhile, the LTO and LMO films had almost equal capacity ranging from 0.1 to 0.8 mA cm À2 . In conclusion, LMO and LTO films achieved the matched charge storage capabilities and EC behaviors, which promoted the construction of high-performance EC batteries.…”

“…3c, the b values of Peak 1 and Peak 2 were calculated to be 0.36 and 0.35, respectively, which demonstrated that the total capacity of the LTO was mainly controlled by the Li-ions diffusion behavior. 46,47 Here, the area specific capacity was used to evaluate the energy storage performance of the LTO. Fig.…”

Advances in multicolor electrochromic devices based on inorganic materials

“…6(b)). Ding et al 69 employed MnO 2 film as the counter electrode and Prussian blue film as the working electrode to develop a flexible multicolor EC storage device (Fig. 6(c)).…”

Multicolored inorganic electrochromic materials: status, challenge, and prospects

“…16c). 123 During the charging/discharging process, various degrees of yellow, green, and blue corresponded to different energy states. To further expand the range of colors that can be displayed, the combination of WO 3 and SVO electrodes was proposed to display multiple colors traversing a 2D CIE regional color space.…”