Vibrant Color Palettes of Electrochromic Manganese Oxide Electrodes for Colorful Zn‐Ion Battery

Abstract

Colorful electrochromic batteries operating in the visible region, which display their residual capacity through real‐time color variation, have recently attracted tremendous attention due to the ever‐rising demands of smart electronics. However, the currently available electrochromic batteries incur certain serious limitations, such as, low capacity utilization, non‐aesthetic versatility, and unsatisfactory performance in practical applications. Manganese oxide, as an extensively used cathode material in zinc‐ion batteries (ZIBs), can yield a prominently high energy density, but with a poor electrochromic performance. By designing a metamaterial with a photonic metastructure, manganese oxide can be remolded into an attractive electrochromic electrode, which shows vibrant color palettes capable of accurately displaying the stored energy level. Based on the combined oxidic and reductive coloration in the as‐prepared manganese oxide electrodes, the developed electrochromic ZIB exhibits a high capacity of 283 mAh g−1 at 0.2 A g−1, with an energy retrieval rate up to 72% during the round‐trip solar charging and galvanostatic discharging processes. This electrochromic ZIB with vibrant color palettes exhibits promising application in next‐generation electrochromic devices with multiple functionalities.

Photochromic and Electrochromic Hydrogels Based on Ammonium- and Sulfonate-Functionalized Thienoviologen Derivatives

“…Photochromic (PC) and electrochromic (EC) materials, whose colors can be reversibly changed upon light and electricity stimuli, have attracted increasing interest due to their extensive applications in displays, optical switches, sensors, energy storage devices, and information storage devices. − Among various smart materials, viologens, i.e., 1,1′-dialkyl-4,4′-bipyridine salts, have become one of the most representative organic PC and EC molecules due to their excellent optical contrast in response to both light and electricity. − Upon light irradiation, colorless viologens change to colored radical cations owing to the reduction of one pyridinium unit caused by photoinduced electron transfer. , However, the colored species always spontaneously disappear in the liquid media because the rate of back electron transfer is rapid and accelerated by the existence of oxygen or other oxidants in the system. , Therefore, to achieve visible photochromism, viologens have been usually dispersed in polar aprotic matrices, such as poly­( N -vinylpyrrolidone) (PVP), to form solid films or quasi-solid gels . For further applications, the latter is usually preferred due to the facile functionalization.…”

Deep eutectic solvent‐based gel electrolytes for flexible electrochromic devices with excellent high/low temperature durability

“…Thus, they have a high potential for numerous applications, including energy-efficient information displays, electronic labels, smart windows, switchable mirrors, adaptive camouflage, and other cutting-edge applications. [1][2][3][4][5][6][7][8][9][10] With the increasing interest in flexible and wearable electronics in recent years, diverse electrolyte strategies have been developed to improve the ionic conductivity and mechanical properties. [11][12][13][14] However, the design of flexible ECDs that can function at extreme temperatures (below 0 C and above 60 C) is severely hampered by the inadequate choice of electrochromic electrolytes, 15,16 which basically restricts an increased deployment of such ECDs in critical areas such as space environments, hot deserts, and high-latitude regions.…”

“…Electrochromic devices (ECDs) can reversibly change colors in response to a change in the applied voltage. Thus, they have a high potential for numerous applications, including energy‐efficient information displays, electronic labels, smart windows, switchable mirrors, adaptive camouflage, and other cutting‐edge applications 1–10 . With the increasing interest in flexible and wearable electronics in recent years, diverse electrolyte strategies have been developed to improve the ionic conductivity and mechanical properties 11–14 .…”

An energy-saving, bending sensitive, and self-healing PVA-borax-IL ternary hydrogel electrolyte for visual flexible electrochromic strain sensors

“…in the visible and near-infrared regions by inducing redox reactions with an external electric field. 1 Due to their unique optoelectronic properties such as low driving voltage, high optical contrast, and long cycle life, ECDs are widely used in smart windows, 2–4 smart labels, 5 electrochromic energy storage, 6 military camouflage, 7 supercapacitors, 8 wearable devices, 9 sensors, 10 etc.…”