Electrochemical Reduction of Oxygen and Nitric Oxide on Mn-Based Perovskites with Different A-Site CationsRead the full article
International Journal of Electrochemistry publishes research on all aspects of electrochemistry including fundamental electrochemical processes, new electrochemical techniques and the applications of electrochemistry in analytical determination.
Professor Kenneth Ozoemena, the journal’s Chief Editor, is based at the University of the Witwatersrand in South Africa. His current research activities include materials synthesis and characterisation, electroanalytical chemistry, electrocatalysis and electrochemical energy conversion and storage.
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Low-Temperature Conductivity Study of Multiorganic Solvent Electrolyte for Lithium-Sulfur Rechargeable Battery Application
The conductivity of an electrolyte plays a significant role in deciding the performance of any battery over a wide temperature range from −40°C to 60°C. In this work, the conductivity of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at a varied salt concentration range from 0.2 M to 2.0 M in a multisolvent organic electrolyte system over a wide temperature range from −40°C to 60°C is reported. The mixed solvents used were 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), and tetraethylene glycol dimethyl ether (TEGDME) with an equal ratio of DOL : DME : TEGDME (1 : 1 : 1 by volume). The experimental analysis performed over a wide temperature range revealed the maximum conductivity at salt concentrations ranging from 1.0 M to 1.4 M for equal molar solvents. The optimum salt concentration and maximum conductivity in a different solvent composition ratio (i.e., 3 : 2 : 1) for all the temperatures is reported herein. The temperature-dependence conductivity of the salt concentration did not fit the Arrhenius plot, but it resembled the Vogel–Tamman–Fulcher plot behavior. The present conductivity study was carried out to evaluate the overall operable temperature limit of the electrolyte used in the lithium-sulfur battery.
Straight-Parallel Electrodes and Variable Gap for Hydrogen and Oxygen Evolution Reactions
The challenges to be overtaken with alkaline water electrolysis are the reduction of energy consumption, the maintenance, and the cost as well as the increase of durability, reliability, and safety. Having these challenges in mind, this work focused on the reduction of the electrical resistance of the electrolyte which directly affects energy consumption. According to the definition of electrical resistance of an object, the reduction of the space between electrodes could lower the electrical resistance but, in this process, the formation of bubbles could modify this affirmation. In this work, the performance analyses of nine different spaces between stainless steel 316L electrodes were carried out, although the spaces proposed are not the same as those from the positive electrode (anode) to the separator and from the separator to the negative electrode (cathode). The reason why this is studied is that stoichiometry of the reaction states that two moles of hydrogen and one mole of oxygen can be obtained per every two moles of water. The proposed spaces were 10.65, 9.20, 8.25, 7.25, 6.30, 6.05, 4.35, 4.15, and 3.40 millimetres. From the nine different analysed distances between electrodes, it can be said that the best performance was reached by one of the smallest distances proposed, 4.15 mm. When the same distance between electrodes was compared (the same and different distance between electrodes and separator), the one that had almost twice the distance (negative compartment) presented an increase in current density of approximately 33% with respect to that where both distances (from electrodes to separator) are the same. That indicates that the stichometry of the electrolysis reaction influenced the performance.
Increased Cycling Performance of Li-Ion Batteries by Phosphoric Acid Modified LiNi0.5Mn1.5O4 Cathodes in the Presence of LiBOB
LiNi0.5Mn1.5O4 (LNMO), which has an operating voltage of 4.8 vs Li/Li+ and a theoretical capacity of 147 mAh g−1, is an interesting cathode material for advanced lithium ion batteries. However, electrolyte decomposition at the electrode can gradually decrease the capacity of the battery. In this study, the surface of the LNMO cathode has been modified with phosphoric acid (PA) to improve the capacity of the LNMO/graphite full cell. Modification of LNMO cathodes by PA is confirmed by surface analysis. Additionally, the presence of lithium bis-(oxalato) borate (LiBOB) as an electrolyte additive further enhances the performance of PA modified LNMO/graphite cells. The improved performance of PA modified cathodes and electrolytes containing LiBOB can be attributed to the suppressed Mn and Ni deposition on the anode. Elemental analysis suggests that the Mn and Ni dissolution is significantly reduced compared to unmodified LNMO/graphite cells with standard electrolyte.
Synthesis, Cyclic Voltammetric, Electrochemical, and Gravimetric Corrosion Inhibition Investigations of Schiff Base Derived from 5,5-Dimethyl-1,3-cyclohexanedione and 2-Aminophenol on Mild Steel in 1 M HCl and 0.5 M H2SO4
Schiff base 2,2’-(5,5-dimethylcyclohexane-1,3-diylidene)bis(azan-1-yl-1-ylidene) diphenol (DmChDp) was synthesized and characterized using spectroscopic methods (IR, UV, NMR, and Mass) and cyclic voltammetric (CV) studies. The corrosion inhibition potency of (DmChDp) on mild steel (MS) in 1M HCl and 0.5M H2SO4 was investigated. The corrosion monitoring techniques employed for this purpose are gravimetric and electrochemical methods (EIS and potentiodynamic polarization studies). The study reveals that the Schiff base, DmChDp, acts as excellent corrosion inhibitor on mild steel in 1M HCl. DmChDp obeys Langmuir adsorption isotherm both in 1M HCl and 0.5M H2SO4 on MS. Polarization studies show that DmChDp behaves as a mixed type inhibitor in both media. Scanning electron microscopic analysis established the protective nature of DmChDp on mild steel surface. The impact of temperature on the corrosion of MS was also evaluated using gravimetric method.
Electrical Conductivity of Films Formed by Few-Layer Graphene Structures Obtained by Plasma-Assisted Electrochemical Exfoliation of Graphite
Current-voltage characteristics of few-layer graphene structures (FLGS) obtained by plasma-assisted electrochemical exfoliation of graphite in Na2SO4 solution were measured. FLGS are shown to possess electronic conductivity, which indicates the predominant functionalization of the edges of graphene planes and the preservation of the structure of basal planes in obtained nanostructures as in the source graphite. The effect of humidity on the conductivity of FLGS films was studied. The resistance of films was found to increase with an increase in the relative humidity of the environment due to the shielding of FLGS flakes by a film of water. The effect of different solvents on the current-voltage characteristics of FLGS was analyzed. The conductivity of films significantly decreased in vapors of polar protic solvents, while there was a minor effect of nonpolar aprotic solvents on the conductivity of FLGS films.
Development of an In-Field Method for the Detection of Barium in Various Water Samples Using Differential Pulse Anodic Stripping Voltammetry
This work presents a reliable, cost-effective, rapid and in-field voltammetric method for the detection of barium. The optimized method consists of an ultrathin mercury film deposited in situ on a glassy carbon electrode in dilute potassium chloride without deoxygenation, using differential pulse anodic stripping voltammetry (DP-ASV). Application of the method allowed for the quantitative determination of barium concentration in a variety of waters and brake pad dust samples. Comparative analysis of sample results from DP-ASV with inductively coupled plasma mass spectroscopy (ICP-MS) showed a mean percent difference of 1.8%.