Long-Lasting Panchromatic Electrochromic Device and Energy-Dense Supercapacitor Based on Zn-Doped NiO Microstars and a Redox-Active Gel

Abstract

The technological importance of cost-effective zinc-doped nickel oxide (Zn:NiO) coatings is demonstrated by applying them to energy saving-electrochromic devices (ECDs) as well as energy storing-asymmetric supercapacitors (ASCs). These devices encompass an inexpensive nonaqueous gel electrolyte of ZnCl 2 /γ-butyrolactone/ ferrocene (Fc)/poly(vinyl butyral), where Fc serves as a redox mediator and accelerates charge transfer and transport kinetics, enhancing both ion-storage and optical modulation responses. This report showcases the prowess of a simple doping and a redox-gel in an unprecedented manner, wherein the improved dc and ac electrical conduction by an order of magnitude, the star-like morphology of Zn:NiO compared to NiO microflowers, and the high conductivity of the gel (33 mS cm −1 ) come to the fore in an ASC [with activated carbon (AC) derived from corncobs as the anode, Zn:NiO//AC], which delivers a very high specific capacitance (SC) of 460 F g −1 (at 1.25 A g −1 ), comparable to expensive rare oxides, a battery like energy density of 164 W h kg −1 (at 1 kW kg −1 ), and a cycle life of 10,000 cycles with 95% SC retention. The potential of Zn doping is further showcased through the panchromatic visible light modulation of the Zn:NiO//WO 3 ECD, switching reversibly between the colorless and the dark black−brown states, accompanied by a remarkably high integrated transmission modulation (ΔT 400−900nm ) of 60.2%, sustained over 3500 cycles with no performance loss, and color/bleach times of 10 s/5 s, most suitable for smart window applications.

Low cost & quasi solid state Na2Mn0.5Ni0.5Fe(CN)6//NaxFe2O3 hybrid Na-ion batteries for solar energy storage

“…Herein, single wall carbon nanotube (SWCNT) coated stainless steel (SS304) sheets were employed as low cost current collectors, where the SWCNT coating minimizes the corrosion and improves the electrolyte stability window. 36 In the threeelectrode cell, the active material coated current collector was used as a working electrode, while a pristine current collector and Ag/AgCl served as the counter and reference electrodes, respectively. The working electrodes were prepared through slurry coating onto the current collectors by a doctor blade method (geometric area: 1 cm 2 & mass loading: 1 mg cm −2 ), where the active material slurry was prepared by homogeneous mixing of 80% active material, 10% conducting carbon black and 10% polyvinylidene uoride (PVDF) binder in dimethyl formamide (DMF) solvent.…”

“…It is mentioned in our earlier publication that PBA are known to form in different crystal structures, like monoclinic, cubic and orthorhombic phases. 36 Herein, the PXRD pattern of Mn-PBA was carefully analysed and rened with the monoclinic phase, 20 and the Rietveld renement results are presented in Fig. 1(a) and Table S2 in the ESI.…”

“…† The Mn(NC) 6 octahedra alternate with the Fe(CN) 6 octahedra along the crystallographic a direction leading to the formation of a three-dimensional open framework structure with one-dimensional channels of Na atoms as described earlier. 36 Similarly, MnNi-PBA also crystallizes in the isostructural monoclinic phase 37 13(2)°) in which the Mn-site of Mn-PBA is occupied by Ni and Mn together (atomic ratio: 1 : 1). The resulting crystal structure of MnNi-PBA is depicted in Fig.…”