Interfacial Charge Transfer and Zinc Ion Intercalation and Deintercalation Dynamics in Flexible Multicolor Electrochromic Energy Storage Devices

Abstract

Bifunctional electrochromic devices integrating electrochromism and energy storage have attracted extensive attention in recent years. Here, zinc-ion-intercalation-based multicolor electrochromic energy storage devices (EESDs) based on a free-standing Zn2+-based polymeric electrolyte membrane (ZPEM) and a nanocrystal-in-glass V2O5 thin film were constructed. Evolution of the interlayer spacing, V–O-related bonds, and chemical compositions of the V2O5 thin films with zinc ion intercalation and deintercalation is elaborated in a liquid Zn­(CF3SO3)2-propylene carbonate (PC) electrolyte. Impressively, highly reversible multi-electrochromism among greenish-blue, yellowish-green, greenish-yellow, faint-yellow, yellowish-orange, and reddish-orange colors is observed in both flexible V2O5 thin films and flexible ZPEM/V2O5/indium tin oxide (ITO) EESDs, which enjoy the benefits from the free channel originating from the large interlayer spacing, the buffering effect of the amorphous phase in the host nanocrystal-in-glass V2O5 matrix, the robust electrostatic interactions between the host V2O5 and guest Zn2+, and Faradaic redox reactions at the Zn2+/V2O5 active interface. The flexible multicolor EESD based on zinc ion intercalation and deintercalation exhibits remarkable electrochromic and energy storage performance with a high transmittance modulation of 57.88%, an excellent coloration efficiency of 36.91 cm2 C–1, a superior specific capacitance of 51 μF cm–2, an enhanced rate capacity, and a pseudocapacitive feature, making it a promising candidate for cost-efficient, environmentally friendly, and bifunctional electrochromic devices.

In Situ Raman Observation of Dynamically Structural Transformation Induced by Electrochemical Lithium Intercalation and Deintercalation from Multi‐Electrochromic V2O5 Thin Films

“…Apparently, the diffusion coefficient of reduction peak is about 2.5 and 1.2 times larger than that of oxidation peak 1 and 2, respectively, suggesting that intercalation is easier than deintercalation for lithium ions. The most plausible explanation can be concluded that the intercalation of lithium ions into the V 2 O 5 thin film during the reduction process leads to the transformation from a semiconductor (V 2 O 5 ) to a conductor (Li x V 2 O 5 ), [ 8 ] and thus the V 2 O 5 thin film in the reduced state exhibits faster ion transfer kinetic compared to the V 2 O 5 thin film in the oxidized state. [ 26 ] Furthermore, the diffusive effect of lithium ions at different redox peaks can be characterized by the following Equation () [ 27 ] $$\[ \begin{array}{*{20}{c}}{i\; = {a^v}b}\end{array} \]$$where a and b (the slope of the “log v − log i ” line) are parameters, i and v are the peak current and scan rate in CV curves, respectively.…”

“…[5,6] Both amorphous and crystalline layered V 2 O 5 thin films enable reversibly electrochemical conduction cations intercalation and deintercalation enjoy multi-electrochromic performance, [5,7] accompanying a reversible redox reaction from V 2 O 5 to M x V 2 O 5 (M = Li, Na, Zn). [1,8,9] For instance, the nanocrystal-in-glass (nanocrystals embedded amorphous matrix) V 2 O 5 thin films with large interlayer spacing can withstand stress caused by intercalation/deintercalation of conduction ions into/from the host structure, thereby avoiding the collapse of the host structure of the film and realizing the reversible insertion of lithium ions. [8,10] The interface between the V 2 O 5 thin films and electrolytes has been shown to be crucial in determining the electrochemical and electrochromic properties.…”

“…[1,8,9] For instance, the nanocrystal-in-glass (nanocrystals embedded amorphous matrix) V 2 O 5 thin films with large interlayer spacing can withstand stress caused by intercalation/deintercalation of conduction ions into/from the host structure, thereby avoiding the collapse of the host structure of the film and realizing the reversible insertion of lithium ions. [8,10] The interface between the V 2 O 5 thin films and electrolytes has been shown to be crucial in determining the electrochemical and electrochromic properties. While ex situ methods have yielded a great deal of information for understanding electrochemical lithium intercalation and deintercalation processes, [11][12][13] the operation dynamics of the V 2 O 5 -electrolyte system can be best revealed via in situ methods.…”

Recent advances in vanadium pentoxide (V2O5) towards related applications in chromogenics and beyond: fundamentals, progress, and perspectives

“…214 Stacked multilayer film exhibits a fast response time with t c /t b = 20.9/34.4 s and excellent stability with 17.75% decreased DT after 2000 cycles. 244 In contrast, ultrathin NS (4 to 40 nm) EC material showed a rapid t c -t b of 4.1-6.4 s but has poor stability with 35% decreased DT after 100 cycles. 245 Surca et al 243 synthesized NPs (100 nm) using a mechanical milling method, and then the film was coated using a spin-coating technique on ITO-PET before being treated thermally at 150 1C for 1 h. Interestingly, DT increases to 6% and 24% after the 41st and 521st cycles, respectively, compared to the 6th cycle.…”

“…90 V 2 O 5 NWs with diameters ranging from 10 to 100 nm and lengths up to several hundred nanometers fabricated by the TE methods were stable for 1000 redox cycles. 60 Other morphologies of V 2 O 5 micro-nanostructures, i.e., NPs, 214,243 stacked multilayer film, 244 and NSs, 245 have been investigated on flexible ECDs. NPs and NSs show excellent contact with a flexible substrate, but the difference in the method and morphology has advantages and disadvantages for each EC material.…”