Electrochemical impedance of ion-exchange systems with weakly charged membranes

Moya, A.A.

doi:10.1007/s11581-013-0850-0

Cited by 8 publications

(8 citation statements)

References 32 publications

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“…Figure 5a displays the Nyquist plots for all samples. The semicircle in the high-frequency range is related to one set of parallel resistor and capacitor [30][31][32]. As shown in Figure 5 and Table 1, DH-7 had the lowest charge-transfer resistance (Rct) and highest DLi, which suggests the highest activity of electrochemical reactions and fastest migration of lithium ions.…”

Section: Resultsmentioning

confidence: 97%

Electrochemical Properties for Co-Doped Pyrite with High Conductivity

Liu

Wang

2015

Energies

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Abstract:In this paper, the hydrothermal method was adopted to synthesize nanostructure Co-doped pyrite (FeS2). The structural properties and morphology of the synthesized materials were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Co in the crystal lattice of FeS2 could change the growth rate of different crystal planes of the crystal particles, which resulted in various polyhedrons with clear faces and sharp outlines. In addition, the electrochemical performance of the doping pyrite in Li/FeS2 batteries was evaluated using the galvanostatic discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. The results showed that the discharge capacity of the doped material (801.8 mAh·g) with a doping ratio of 7% was significantly higher than that of the original FeS2 (574.6 mAh·g −1 ) because of the enhanced conductivity. Therefore, the doping method is potentially effective for improving the electrochemical performance of FeS2.

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Section: Resultsmentioning

confidence: 97%

Electrochemical Properties for Co-Doped Pyrite with High Conductivity

Liu

Wang

2015

Energies

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“…An intercept at the Z' real axis in the high frequency region corresponded to electrolyte resistance, R e , in the equivalent circuits. The semicircle in the intermediate frequency range indicates the charge transfer resistance, R ct , which is related to both the charge transfer through and the double-layer capacitance at the electrode/electrolyte interface [17][18][19]. The shapes of the semicircles provided information pertaining to the charge-transfer resistances of the electrochemical reactions taking place.…”

Section: Electrochemical Impedance Spectroscopy (Eis)mentioning

confidence: 99%

Electrochemical Mechanism for FeS2/C Composite in Lithium Ion Batteries with Enhanced Reversible Capacity

Wang

2016

Energies

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Nanoscale FeS 2 was synthesized via a simple hydrothermal method and was decorated by hydrothermal carbonization (FeS 2 @C). The structural properties of the synthesized materials detected by X-ray diffraction (XRD), together with the morphologies characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the hydrothermal carbonization only had an impact on the morphology of pyrite. Additionally, the electrochemical performance of the coated pyrite in Li/FeS 2 batteries was evaluated by galvanostatic discharge-charge tests and electrochemical impedance spectroscopy (EIS). The results showed that the initial capacity of FeS 2 @C was 799.2 mAh¨g´1 (90% of theoretical capacity of FeS 2 ) and that of uncoated FeS 2 was only 574.6 mAh¨g´1. XRD and ultraviolet (UV) visible spectroscopy results at different depths of discharge-charge for FeS 2 were discussed to clarify the electrochemical mechanism, which play an important part in Li/FeS 2 batteries.

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“…This approach is based on the numerical solution of the Nernst–Planck, Poisson equations with a special boundary condition for the electric potential. Unlike potentiodynamic models [16,17,18,19,20,21,22,23,24,25,26,27], where the potential difference was set, in [37,38,39] the electric field strength at the outer edge of the diffusion layer was specified as an explicit function of the current density for the one-dimensional (1D) case. A similar approach was used for the two-dimensional (2D) case in [40] to study the chronopotentiograms (ChP) of ion-selective microchannel-nanochannel devices with current density uniformly distributed along the border; in [41] to study ChP of heterogeneous ion exchange membranes without taking into account the forced flow.…”

Section: Introductionmentioning

confidence: 99%

2D Mathematical Modelling of Overlimiting Transfer Enhanced by Electroconvection in Flow-Through Electrodialysis Membrane Cells in Galvanodynamic Mode

Uzdenova

2019

Membranes

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Flow-through electrodialysis membrane cells are widely used in water purification and the processing of agricultural products (milk, wine, etc.). In the research and operating practice of such systems, a significant place is occupied by a galvanodynamic (or galvanostatic) mode. 2D mathematical modelling of ion transfer in the galvanodynamic mode requires solving the problem of setting the average current density equal to a certain value, while the current density distribution in the system is uneven. This article develops a 2D mathematical model of the overlimiting transfer enhanced by electroconvection in a flow-through electrodialysis cell in the galvanodynamic mode. The model is based on the system of Navier–Stokes, Nernst–Planck, Poisson equations and equations for the electric current stream function. To set the electric mode we use a boundary condition, relating the electric field strength and current density. This approach allows us to describe the formation of the extended space charge region and development of electroconvection at overlimiting currents. For the first time, chronopotentiograms and current–voltage characteristics of the membrane systems are calculated for the galvanodynamic mode taking into account the forced flow and development of electroconvection. The behaviors of the calculated chronopotentiograms and current–voltage characteristic coincide qualitatively with experimental data. The effects of the electrolyte concentration, forced flow velocity and channel size on the mass transfer at overlimiting currents are estimated.

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Electrochemical impedance of ion-exchange systems with weakly charged membranes

Cited by 8 publications

References 32 publications

Electrochemical Properties for Co-Doped Pyrite with High Conductivity

Electrochemical Properties for Co-Doped Pyrite with High Conductivity

Electrochemical Mechanism for FeS2/C Composite in Lithium Ion Batteries with Enhanced Reversible Capacity

2D Mathematical Modelling of Overlimiting Transfer Enhanced by Electroconvection in Flow-Through Electrodialysis Membrane Cells in Galvanodynamic Mode

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