Ultra‐Thin Manganese Dioxide‐Encrusted Vanadium Pentoxide Nanowire Mats for Electrochromic Energy Storage Applications

Abstract

is relatively inexpensive and eco-friendly material that exhibits outstanding theoretical capacitance values with a distinct electro-polychromism. [17] However, studies exploiting their concurrent electropolychromism and energy-storing performance in devices are still aberrant. The main hindrance in V 2 O 5 electrode usage for potential commercial applications is their electrochemical instability, write-erase stability, and trapping-related degradations. [18] Constructing the thin film-based EESD electrodes needs a critical selection of components. In principle, the components should offer synergistic enhancements in the charge capacitance and also produce obvious color change during the charge insertion/extraction. Such bifunctionality could be used for either online charge level monitoring or in the energy storing smart window applications. Moreover, the electrochemical stability of transparent conductors must not be compromised by the adopted process as explained by the work of Cai et al. [19] Typically, researchers employ techniques like nanostructuring [20] or binary [21] /ternary [22] hybridizations of materials as effective ways to improve the capacitance of TMOs. The synergistic effect of a thin layer of TMOs on V 2 O 5 nanostructure in enhancing the capacitance and cyclic stability is described in some recent publications. [23,24] These reports highlighted the modifications in the electronic structure and chemical environment of V 2 O 5 that led to the electrode performance enhancements.Research on V 2 O 5 -based EESDs is still in its infancy with only a few reports appeared in the literature. An EC supercapacitor with V 2 O 5 in gyroid nanostructure is reported by Wei et al. [25] They observed a reduction in the initial specific capacitance to half of the value within the first few cycles before stabilization to a constant value of 155 F g −1 . This behavior was attributed to the structural instability of the gyroid nanostructure, which points to the fact that the capacitance retention is a serious issue even in a controlled nanostructuring of V 2 O 5 . In another paper, carbon nanosphere-decorated V 2 O 5 hybrid nanobelts were synthesized, and the effect of annealing on the capacitance and EC property was studied. [8] In the study, the film with higher capacitance is having a relatively slow response time. More attempts are required for the matured development/understanding of better V 2 O 5 based electrode materials V 2 O 5 electrochromic (EC) coatings are attractive for various photonic applications owing to their multiple oxidation states discernable by distinct colors. The material also shows massive potential for electrochemical energy storage because of their layered structure and high theoretical capacitance. Here, the solution processing of the electrodes composed of an ultra-thin layer of MnO 2 -encrusted V 2 O 5 (V 2 O 5 /MnO 2 ) nanowire mats on fluorinated tin oxide substrates is reported that offer much enhanced electrochemical stability along with a superior energy storage performance com...

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

“…This is favored by the many electroactive sites and favors the chargetransfer resistance. 57 Emphasizing this morphology, 1D nanostructured V 2 O 5 as an EC layer, such as NRs, 82,83,150,184 NWs, 59,60,89,90 NBs, 93 and NFs, 57 has been reported.…”

“…85,87 Micrometer-, centimeter-, and ultra-long NWs, NFBs, NSPs, and NRs were formed as a result of a continuous process in a long-term reaction. 37,47,59,60,[88][89][90][91] Similarly, this process can lead to the diameter increase or assembly of NWs and NFBs to form NBs. 86,92,93 The bent layers (for a = 901) may form nanoscrolls, NHLs, or closed NTs, as shown in Fig.…”

“…For example, when x = 0.5 and 1, green and blue colors are observed, as shown in eqn ( 15) and ( 16), respectively. 90 On the other hand, the specific relationship between the x value and color of ECDs depends on the intrinsic film.…”

“…89 Multicolor (black, pale, yellow, light yellow, and dark green) V 2 O 5 / PANI CDs demonstrated cycling stability for 1000 cycles and rapid bleaching-coloration times of 1.5-2.3 s. The optical contrast retention at 1000 cycles was 85% for MnO 2 -entrusted V 2 O 5 compared to 80% for bare V 2 O 5 . 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.…”

“…The proposed strategies to improve the performance include doping through the addition of Ti in V 2 O 5 283 to promote lattice distortion and the increase in ion insertion kinetics along with the addition of another oxide, such as MnO 2 , providing enhanced stability and increased energy storage performance. 90 Furthermore, V 2 O 5 has a unique band structure allowing it to absorb almost the entire solar spectrum. Therefore, the incorporation of EC materials and batteries (or supercapacitor) to form EC energy storage devices (EESDs), 184,[283][284][285] using a solar cells and EC materials to form photo-electrochromic devices (PECDs), 259 using the battery (or supercapacitor) with a solar cell to form photo-recharge energy storage devices (PRESDs) and using solar cells and CDs to form photovoltachromic devices (PVCDs) 286 are an advantage in energy-saving applications.…”