Search

The increased interest in the transition from liquid to solid polymer electrolytes (SPEs) has driven enormous research in the area polymer electrolyte technology. Solid biopolymer electrolytes (SBEs) are a special class of SPEs that are obtained from natural polymers. Recently, SBEs have been generating much attention because they are simple, inexpensive, and environmentally friendly. In this work, SBEs based on glycerol-plasticized methylcellulose/pectin/potassium phosphate (MC/PC/K3PO4) are investigated for their potential application in an electrochemical double-layer capacitor (EDLC). The structural, electrical, thermal, dielectric, and energy moduli of the SBEs were analyzed via X-ray diffractometry (XRD), Fourier transforms infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS), transference number measurement (TNM), and linear sweep voltammetry (LSV). The plasticizing effect of glycerol in the MC/PC/K3PO4/glycerol system was confirmed by the change in the intensity of the samples' FTIR absorption bands. The broadening of the XRD peaks demonstrates that the amorphous component of SBEs increases with increasing glycerol concentration, while EIS plots demonstrate an increase in ionic conductivity with increasing plasticizer content owing to the formation of charge-transfer complexes and the expansion of amorphous domains in polymer electrolytes (PEs). The sample containing 50% glycerol has a maximal ionic conductivity of about 7.5 × 10−4 scm−1, a broad potential window of 3.99 V, and a cation transference number of 0.959 at room temperature. Using the cyclic voltammetry (CV) test, the EDLC constructed from the sample with the highest conductivity revealed a capacitive characteristic. At 5 mVs−1, a leaf-shaped profile with a specific capacitance of 57.14 Fg−1 was measured based on the CV data. [ABSTRACT FROM AUTHOR]

Presently, the rising concerns about the fossil fuel crisis and ecological deterioration have greatly affected the world economy and hence have attracted attention to the utilization of renewable energies. Among the renewable energy being developed, supercapacitors hold great promise in broad applications such as electric vehicles. Presently, the main challenge facing supercapacitors is the amount of energy stored. This, however, does not satisfy the increasing demand for higher energy storage devices, and therefore, intensive research is being undertaken to overcome the challenges of low energy density. The purpose of this review is to report on solid polymer electrolytes (SPEs) based on polyvinyl alcohol (PVA). The review discussed the PVA as a host polymer in SPEs followed by a discussion on the influence of conducting salts. The formation of SPEs as well as the ion transport mechanism in PVA SPEs were discussed. The application and development of PVA-based polymer electrolytes on supercapacitors and other energy storage devices were elucidated. The fundamentals of electrochemical characterization for analyzing the mechanism of supercapacitor applications, such as EIS, LSV and dielectric constant, are highlighted. Similarly, thermodynamic transport models of ions and their mechanism about temperature based on Arrhenius and Vogel–Tammann–Fulcher (VTF) are analyzed. Methods for enhancing the electrochemical performance of PVA-based SPEs were reported. Likely challenges facing the current electrolytes are well discussed. Finally, research directions to overcome the present challenges in producing SPEs are proposed. Therefore, this review is expected to be source material for other researchers concerned with the development of PVA-based SPE material. [ABSTRACT FROM AUTHOR]

The oxygen-containing functional groups in graphene oxide (GO) impose considerable limitations in their applications requiring chemical inertness and electrical conductivity such as supercapacitive charge storage. Chemical reduction of GO has been frequently employed; however, processing of large volume of hazardous solvents impose severe environmental concerns. This article demonstrates the optical reduction of freeze dried GO into reduced GO (rGO) by a computer controlled laser engraver as a plug and operate device. The conversion of GO into rGO as a function of laser powers has been monitored by X-ray diffraction, X-ray photon electron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, Thermogravimetric analysis, and field emission scanning microscopy. The rGO thus produced has been evaluated for their charge storage capability in aqueous electrolytes. The best performing laboratory prototype demonstrated one of the best energy density of rGO electrodes in an aqueous electrolyte. The promising properties of the supercapacitors thereby developed as well as cost effectiveness and potential for large scale production engaging laser engraving process, the present work offers numerous potentials for deploying efficient and low cost supercapacitive devices. • Graphene oxide (GO) is physically reduced using a laser engraver. • Oxygen removal efficiency from GO increases with increase in laser power. • Porous network of interconnected few layer rGO sheets are obtained. • rGO sheets engraved using higher laser power showed superior charge storage. • A supercapacitor prototype using the rGO gave specific energy as high as 17 Wh/kg. [ABSTRACT FROM AUTHOR]

• Synthesis of PT/MC/K 2 CO 3 /EC solid polymer electrolytes (SPE) • Design of experiment and analysis of data by RSM. • Optimization and interaction studies by RSM. • Prediction by RSM and experimental validation of optimum response. • Structural studies of optimum sample. • Electrochemical studies of optimum sample. • Fabrication and testing of electrochemical capacitor based on optimum response. In this study, we developed an eco-friendly solid electrolyte by blending pectin (PT) with methylcellulose (MC) and complexed with potassium carbonate (K 2 CO 3) salt and ethylene carbonate (EC) plasticizer. The goal of the study was to understand the salt-plasticizer interaction and to optimize the electrochemical performance using response surface methodology (RSM) within the central composite design (CCD). RSM approach unveiled that K 2 CO 3 and EC interact significantly, impacting the ionic conductivity and potential window of the solid biopolymer electrolytes (SBEs). After optimization, this work achieved ideal conditions with 35.05 wt% K 2 CO 3 and 16.78 wt% EC, yielding an ionic conductivity of ∼ 1 × 10-3 Scm−1 and a 4.77 V potential window. Structural analysis confirmed coordination among constituents and increased amorphous content. This work, therefore, highlights PT/MC/K 2 CO 3 /EC's potential for electrochemical device applications. An electrochemical cell constructed using the optimized sample exhibited the highest specific capacitance of 50.74 Fg–1, as determined by cyclic voltammetry (CV) analysis. [ABSTRACT FROM AUTHOR]

Charge accessibility in nanotube electrodes and consequent electrochemical properties exploitable for energy storage and sensing device is higher due to their dual surfaces than solid nanowires; however, their controlled growth is often challenging. This article demonstrates synthesis of metal nanowires of cobalt and nickel using a template-assisted electrodeposition technique and its transformation into cobalt oxide (Co 3 O 4) and nickel oxide (NiO) nanotubes by controlled annealing. The materials are characterized for their phase, surface, and morphology. The Co 3 O 4 nanotubes has a spinal-type crystal structure, an inner diameter of ~100 nm and wall thickness of ~220 nm with uniform micropores centered at ~21 nm, whereas NiO has a face centered cubic crystal structure, inner diameter ~90 nm and wall thickness ~330 nm with uniform micropores centered at ~21 nm. The electrochemical charge storability of the nanotubes is evaluated in an aqueous alkaline electrolyte (6 M KOH) using a three-electrode system measurement. The Co 3 O 4 and the NiO nanotubes delivered discharge specific charges of ~324 and ~263 C g−1, respectively, the difference charge storability is attributed to the surface and electrochemical properties. Further, a battery – electrochemical capacitor hybrid device is developed with desirable charge storage performance indicators using the Co 3 O 4 nanotubes and reduced graphene oxide as positive electrode and negative electrode, respectively. This research thereby provides a method for developing scalable, reproducible, and efficient battery-electrochemical capacitor hybrid device using NiO and Co 3 O 4 nanotubes. • Co 3 O 4 and NiO nanotubes are synthesized via template-assisted electrodeposition. • The tubes had higher wall thickness than inner diameter for operational stability. • The nanotubes showed superior surface properties for charge storage. • Co 3 O 4 showed lower electrochemical resistance due to surface characteristics. • A battery – electrochemical capacitor hybrid is fabricated using the Co 3 O 4 nanotubes. [ABSTRACT FROM AUTHOR]