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The electrochemical properties of polymerized aniline (PANI) and polymerized melamine (PMEL) that were electrochemical copolymerized (PANIMEL) on a glassy carbon electrode (GCE) that had been coated with functionalized multiwalled carbon nanotubes (fMWCNT) to form a PANIMEL/fMWCNT/GCE film electrode were studied, with an aim toward electrochemical energy storage (EES). A number of factors, such as the choice of working electrode, electrolyte, switching potential, applied scan rate, and type of fMWCNTs, were initially investigated and evaluated during the individual electrochemical polymerization of aniline and melamine via successive potential cycling. The electrochemical copolymerisation of aniline and melamine was then studied with an ideal monomeric ratio of 1:3 that gave an optimal ratio of the voltammetric peak current heights with distinguishable redox peak potentials. Variable scan rate cyclic voltammetry (CV) of the electrosynthesized copolymer film electrode confirmed the dominance of the surface-confined electron transfer process at the electrode. The electrochemical stability of the copolymer film electrode was also assessed and revealed a limited cyclability of the daughter polymeric melamine, which was hypothesized to be due to an excessive nitrogen content combined with a low porosity that led to a poor ion intercalation-deintercalation mechanism. Electrochemical impedance spectroscopy (EIS) was performed to evaluate the electrochemical performance of the copolymerized film electrode with other control electrodes. The corresponding EIS results suggested that the copolymerized film electrode was electrochemically superior to the PMEL/fMWCNT/GCE film electrode but was inferior to the PANI/fMWCNT/GCE film electrode. [ABSTRACT FROM AUTHOR]

Summary: The operation of electrochemical capacitors depends not only on extrinsic operating and design parameters, but also intrinsic physical, material, and electrochemical parameters. Fluctuations in these stochastic parameters can significantly influence the performance and may lead to quicker degradation of the electrochemical capacitors, thereby affecting their durability and reliability. Thus, it is important to quantify the sensitivities of these extrinsic and intrinsic parameters and correlate them with the performance, to delay the inevitable performance degradation. To achieve this, we perform Monte Carlo simulations (MCS) followed by sensitivity analysis under high and low charge/discharge current (load) conditions. The MCS is statistically performed by varying all the stochastic parameters simultaneously. We then identify the critical parameters that affect the performance under different load conditions, which provides insights into optimal operation of electrochemical capacitors. The thickness of positive electrode and the radius of active material were identified as the most significant parameters under low and high load conditions, respectively. Furthermore, we derive reduced order surrogate models with at least 95% accuracy using supervised machine learning techniques to predict the performance without solving the full physics‐based model. [ABSTRACT FROM AUTHOR]

A simple electrochemical method using ac voltammetry to detect aqueous droplets up to 480 droplets per second in a flow-focusing microfluidic device is presented. The method offers a promising and versatile platform with simple and inexpensive instrumentation for droplets real time detection and preliminary characterization. [ABSTRACT FROM AUTHOR]

The application of the boundary element method (BEM) as an efficient and powerful method for the analysis of the time-dependent electrochemical processes at multiple electrode configurations is presented. The paper describes the theory and numerical details required for developing one-, two- and three-dimensional transient diffusion models for chronoampermetric simulations under diffusion control. The benefits of the BEM approach are discussed, including the reduction in dimensionality brought about by the formulation procedure and complete elimination of the need for domain discretisation with the time-domain convolution approach. The versatility and efficiency of the numerical procedures are examined with respect to a number of electrode geometries. Results are presented for chronoamperometric simulations at microband, microhemishpere, microcylinder and microdisc electrodes compared to appropriate analytical theory. The three-dimensional simulations focus on the modelling of double-electrode configurations (microdisc and microhemisphere) operating in a generator–collector mode. The influence of electrode separation on the transient current response is presented and normalised working curves currently unavailable via analytical methods are provided. [Copyright &y& Elsevier]

A tubular flow cell under pressure driven control is used to illustrate a numerically efficient approach to the simulation of hydrodynamically stepped current/time transients. A simple redox reaction is used to illustrate the voltammetric response within a tubular cell to an instantaneous pressure change. To simplify the presentation of data, a normalisation method is proposed and shown to be valid for situations in which a pressure step occurs. [Copyright &y& Elsevier]

Abstract: The article describes a numerical and experimental investigation of the voltammetric response observed within small-scale electrochemical reactors, where reagents are directed to a sensor electrode using hydrodynamic focusing. A microelectrochemical reactor was developed, fabricated and tested for electrochemical sensitivity. The studies presented examine the influence of stream velocity, lead-in length and focusing stream ratios on the electrolytic current induced. The numerical models reveal a regime where the finely focused stream of reagent responds in an identical manner to a cell completely full of reagent and also to a regime where diffusional broadening of the reagent stream into the carrier stream becomes significant with a resulting loss in voltammetric sensitivity. In addition at higher focusing ratios, where the reagent occupies a much smaller portion of the channel, full electrochemical depletion of the species is possible at substantially greater throughput rates than is feasible without the focusing arrangement. Experimental studies show qualitative agreement with numerical predictions. [Copyright &y& Elsevier]

Design and sizing of lithium-ion battery is a challenging task because of inherent multiphysical and multiscale nature of this battery type. Detailed mechanistic models have been developed to resolve the design effects on physico-chemical processes taking place inside the battery and in turn, on battery performance. However, such models are hold back by their mathematically complexity and associated computational cost. In this paper, we come up with efficient design guidelines for Li-ion battery while addressing these model complexities. In essence, we carry out scale analysis of electrochemical and thermal behaviour of a cylindrical spiral wound Li-ion battery. We secure non-dimensional numbers and scales for the leading-order phenomena of charge, energy and species transport as well as associated heat generation and electrochemical reactions. The scales, in particular, provide quick quantification of variables such as temperature increase, potential losses and state of charge during charge/discharge. We verify reliability of the derived scales by comparing their predictions with the results from numerical simulations of an electrochemical-thermal model of battery. Overall, good agreement between the predictions from scales and simulations is obtained. The non-dimensional numbers and scales – which characterize the cell both thermally and electrochemically – are also discussed from the viewpoint of battery design. [ABSTRACT FROM AUTHOR]