Stoichiometrically Optimized Electrochromic Complex [V₂O_2+ξ(OH)_3‐ξ] Based Electrode: Prototype Supercapacitor with Multicolor Indicator

Abstract

The systematic structure modification of metal oxides is becoming more attractive, and effective strategies for structural tunning are highly desirable for improving their practical color‐modulating energy storage performances. Here, the ability of a stoichiometrically tuned oxide‐hydroxide complex of porous vanadium oxide, namely [V2O2+ξ(OH)3‐ξ]ξ = 0:3 for multifunctional electrochromic supercapacitor application is demonstrated. Theoretically, the pre‐optimized oxide complex is synthesized using a simple wet chemical etching technique in its optimized stoichiometry [V2O2+ξ(OH)3‐ξ] with ξ = 0, providing more electroactive surface sites. The multifunctional electrode shows a high charge storage property of 610 Fg−1 at 1A g−1, as well as good electrochromic properties with high color contrast of 70% and 50% at 428 and 640 nm wavelengths, faster switching, and high coloration efficiency. When assembled in a solid‐state symmetric electrochromic supercapacitor device, it exhibits an ultrahigh power density of 1066 mWcm−2, high energy density of 246 mWhcm−2, and high specific capacitance of 290 mFcm−2 at 0.2 mAcm−2. A prepared prototype device displays red when fully charged, green when half charged, and blue when fully discharged. A clear evidence of optimizing the multifunctional performance of electrochromic supercapacitor by stoichiometrical tuning is presented along with demonstrating a device prototype of a 25 cm2 large device for real‐life applications.

Developments in Raman Spectromicroscopy for Strengthening Materials and Natural Science Research: Shaping the Future of Physical Chemistry

“…Therefore, Raman spectroscopy is a versatile and nondestructive analytical technique that plays a crucial role everywhere in materials science and applications . Recently, Raman spectroscopy has been widely used in the field of smart devices such as electrochromic (EC) smart windows, memory devices, etc., for live monitoring of the device performance. , …”

Nano-Nest Type Porous NiCo2S4@polyindole Core–Shell Array: Efficient Energy Storage Supercapacitor Device

“…Fast consumption of fossil energy sources and consequent anticipated crises have been acknowledged globally, and serious efforts are being made to switch to alternate power sources by exploring new and efficient energy conversion and storage devices. − (Super-) capacitors have their practical applicability due to their high power density, fast charge–discharge, easy synthesis, high capacitance retention, high mechanical strength, and better ecological coexistence. − Nevertheless, the low energy density of supercapacitors always restricts their practical applications due to the small operational potential window. , To increase the energy density, asymmetric supercapacitors are fabricated with positive electrodes as high-specific capacitance material to increase the power density and negative electrodes (negatrodes) as carbonaceous material (usually activated carbon) to increase the energy density of the device. , In addition to these carbon materials, transition metal sulfides have emerged as promising positive electrode materials for supercapacitors − owing to the advantages of ultrahigh theoretical specific capacitance, excellent cyclic stability, and fast ion diffusion rate. Among them, NiS x and CoS x are the most reported metal sulfide supercapacitors; however, their specific capacitance is always higher than that of their corresponding metal oxides under the same experimental conditions, which is attributed to their high electrical conductivity. − The specific capacitance can further be improved if dual metal sulfides such as NiCo 2 S 4 (NCS) and CuCo 2 S 4 are used due to their strong redox reactions and high theoretical specific capacitance.…”