Multifunctional electrochromic energy storage devices by chemical cross-linking: impact of a WO3·H2O nanoparticle-embedded chitosan thin film on amorphous WO3 films

Abstract

With the advent of multifunctional devices with electrochromic (EC) behavior and electrochemical energy storage, complementary design of film structures using inorganic-organic materials has shown great potential for developing EC energy storage devices. Herein, hybrid films consisting of WO 3 ·H 2 O nanoparticle (WHNP)-embedded chitosan thin films on amorphous WO 3 (a-WO 3 ) films were designed. By exploiting the hybrid effect of chitosan and WHNPs to generate unique chemical cross-linking between them, the designed films exhibited attractive EC behaviors compared to bare a-WO 3 films. These included fast switching speeds (4.0 s for coloration and 0.8 s for bleaching) due to enhanced electrical conductivity and Li-ion diffusivity, high coloration efficiency (62.4 cm 2 /C) as a result of increased electrochemical activity, and superb long-cycling retention (91.5%) after 1000 cycles due to improved electrochemical stability. In addition, hybrid films exhibited a noticeable energy storage performance with a high specific capacitance (154.0 F/g at a current density of 2 A/g) and a stable rate capability as a result of improved electrochemical activity and fast electrical conductivity, respectively. This resulted in brighter illumination intensity for the 1.5-V white-light-emitting diode due to improved energy density compared to a bare a-WO 3 film. Therefore, the results suggest a new design strategy for materials to realize the coincident application of multifunctional devices with EC energy storage performance.

Two-dimensional WO3 nanosheets for high-performance electrochromic supercapacitors

“…1d, the binding energy peaks at 35.48 and 37.58 eV belong to W 4f 7/2 and W 4f 5/2 , representing W 6+ , while an additional binding energy peak at 41.31 eV was attributed to W 5p 3/2 of the WO 3 NSHs, indicating the chemical value of W was +6. [28][29][30] Furthermore, the O 1s binding energy peak (Fig. 1e) could be resolved into two dominant components at 530.31 and 531.61 eV, corresponding to the lattice oxygen ion and the surfaceabsorbed oxygen species.…”

Extremely fast electrochromic supercapacitors based on mesoporous WO3 prepared by an evaporation-induced self-assembly

“…One key parameter for achieving high-performance ECSs is an EC chromophore. Among EC materials, transition metal oxides such as tungsten trioxide (WO 3 ) have been widely employed to exploit their superior electrochemical properties [16][17][18] , large optical modulation 19,20 , and high coloration efficiency 21,22 . Recently, a few research groups reported ECSs based on WO 3 films [23][24][25][26] .…”

Boosting Transport Kinetics of Ions and Electrons Simultaneously by Ti3C2Tx (MXene) Addition for Enhanced Electrochromic Performance

“…Starting with the fundamental electrochemical reaction, electrochromic performances of the WO 3− x depend on the transport rate of the cations and electrons as well as the ability to accommodate the cations in the film. Different advanced strategies have been studied to improve electrochromic performances such as the combination of crystalline and amorphous WO 3− x [ 20 , 21 ], regulation of nanotopography [ 6 , 22 , 23 ], element doping [ 18 , 24 , 25 ], and construction of composite materials [ 26 , 27 ]. On the one hand, the structure construction of tungsten oxide almost concentrates on the transport behavior of cations.…”