Studies on transmittance modulation and ions transfer kinetic based on capacitive-controlled 2D V₂O₅ inverse opal film for electrochromic energy storage application

Abstract

Two-dimensional vanadium pentoxide inverse opal (2D V2O5 IO) architecture was fabricated by polystyrene (PS) sphere template assisted electrodeposition process. In comparison to the un-templated V2O5 film, the 2D V2O5 IO film exhibited a highly ordered hexagonal close-packed bowel-like array, as well as noticeable electrochromism, such as transmittance modulation up to 42.6% at 800 nm, high coloration efficiency (28.6 cm2 · C−1), fast ions transfer kinetic (t b = 7.2 s, t c = 2.5 s). These improvements of electrochromic performance were attributed to the ordered morphology with larger surface areas, which considerably shortened the ions diffusion paths and accelerated ions migration. An electrochromic energy storage device assembled from the 2D V2O5 IO film with simultaneous electrochromic and pseudocapacitive performance could not only show transmittance modulation accompanied by multicolor variations but also powered an LCD screen and an LED bulb, demonstrating a promising potential for practical applications.

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

“…For Figure 2b, the intensity of two new broad peaks located at around 223 (P 1 ) and 800 cm –1 (P 4 ) enhances greatly in the negative‐going sweep (i‐x) and then completely disappear when the potential reaches the first oxidation peak (xvi) in CV process. The result can be attributed to the reversible redox transition of vanadium ions (according to the reaction equation [ 1 ] : V 2 O 5 + xLi + + xe ↔ Li x V 2 O 5 ) caused by the reversible insertion/extraction of lithium ions. [ 1,20–22 ] Figure 2c shows that the intensity of Raman spectra at 994 cm –1 (P 5 ) and 1090 cm –1 (P 6 ) diminishes substantially when the potential tends to be more negative (i‐x), which results from an increase of disorder within the V 2 O 5 thin film and a fairly sharp weakening of the V–O and V–O bonds at deep insertion of lithium ions.…”

“…The result can be attributed to the reversible redox transition of vanadium ions (according to the reaction equation [ 1 ] : V 2 O 5 + xLi + + xe ↔ Li x V 2 O 5 ) caused by the reversible insertion/extraction of lithium ions. [ 1,20–22 ] Figure 2c shows that the intensity of Raman spectra at 994 cm –1 (P 5 ) and 1090 cm –1 (P 6 ) diminishes substantially when the potential tends to be more negative (i‐x), which results from an increase of disorder within the V 2 O 5 thin film and a fairly sharp weakening of the V–O and V–O bonds at deep insertion of lithium ions. [ 12 ] Moreover, the intensity of peaks assignment at 994 cm –1 (P 5 ) and 1090 cm –1 (P 6 ) grows from the first oxidation peak (xvi) and recovers to the original level after the potential reaches the second oxidation peak (xvii) in the positive‐going sweep during CV process, indicating the reversible extraction of lithium ions from the V 2 O 5 thin film.…”

“…For Figure 2b, the intensity of two new broad peaks located at around 223 (P 1 ) and 800 cm -1 (P 4 ) enhances greatly in the negative-going sweep (i-x) and then completely disappear when the potential reaches the first oxidation peak (xvi) in CV process. The result can be attributed to the reversible redox transition of vanadium ions (according to the reaction equation [1] :…”

“…The electrochromic materials, whose optical properties (transmittance, reflectance, and absorbance) reversibly change with transitions in polarity and intensity of an applied electric field, [ 1 ] show increasingly broad prospects due to their huge commercial application potential in the fields of variable reflection mirrors, smart windows, displays, flexible wearable fabric and so on. [ 2–4 ] As the promising electrochromic material that can display both cathodic and anodic coloration, vanadium pentoxide (V 2 O 5 ) has received tremendous research attention owing to its layered structure and several oxidation states (V 2+ to V 5+ ).…”

“…[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.…”