Figure - available from: Journal of The Electrochemical Society
This content is subject to copyright. Terms and conditions apply.
Diagram of the vanadium redox flow battery, including the negative and positive porous electrodes, membrane separator transporting ideally protons (single charged hydrogen), solid current collectors, reservoir (storage tanks) for electrolytes for the electrodes, pumps to push electrolytes into and out of the electrodes, and the total current in the electrical circuit. Current and electron flow appropriate for discharging condition. Charging and discharging currents and their directions are shown. So, are the flow directions of the electrons feeding into the terminals.
Source publication
Vanadium redox flow batteries (VRFB) has been intensively examined since the 1970s, with researchers looking at their electrochemical time varying electrolyte concentration time variation equations for negative and positive half cells, its thermal time variation equations, and fluid flow equations. The chemistry behavior of the electrolyte ions hav...
Similar publications
Citations
... The membranes were equilibrated in testing solution before the measurements. The proton conductivity was calculated by [24] : ...
... The membrane sample was sandwiched between the two chambers (A and B) [ spectrometer at 420 nm. The ferric ion diffusion constant (D diffusion const ) was calculated using Fick's law, denoted as [24,25] : ...
Porous ion-selective membranes are promising alternatives for the expensive perfluorosulfonic acid membranes in redox flow batteries. In this work, novel non-ionic porous polyvinylidene fluoride-hexafluoro propylene membranes are designed for iron-lead single-flow batteries. The membranes are prepared using a multiple template approach, involving simultaneously using polyethylene glycol and dibutyl phthalate (DBP) as pore-forming templates. Their porous structure is finely tuned by adjusting the ratio of the two templates. As a result, dual-porous membranes bearing both macro and micropores are obtained. The H3520 membrane with modified porous structure attains a high proton conductivity of 43.5 mS·cm-1 and a relatively low ferric ion diffusion constant (8.61 × 10-8 cm2·min-1) and demonstrates the best balance between these performance-determining parameters (selectivity 5.04 × 105 S·min·cm-3, higher than that of the N115 membrane). Besides, performance tests of the iron-lead single-flow single cells equipped with the dual-porous membranes show a high energy efficiency, exceeding 87.2% at its rated current density, and outstanding cycling stability over 200 charge-discharge cycles. Altogether, the mixed template method presents a promising strategy to prepare high-performance and low-cost non-ionic membranes for redox flow batteries.
... Experimental tests of our battery have been reported by B. Khaki and P. Das for sensorless parameter estimation regarding capacity fading, 21 an equivalent circuit model, 22 and algorithms for Soc and SoH estimation. 22 Even more recent works addressing fabrication and testing of our battery are available in: Krowne, 165 Nernst equations and overpotential; Krowne, 166 ...
The vanadium redox flow battery has been intensively examined since the 1970s, with researchers looking at its electrochemical time varying electrolyte concentration time variation (both tank and cells, for negative and positive half cells), its thermal time variation, and the fluid flow behavior. Chemistry behavior of the electrolyte ions have also been intensively examined too. Our focus here was to examine the disturbance and effect of other chemical reactions and constituents to those typically found in the positive electrode electrolyte, while handling the less problematic negative electrode. Appropriate formulas are developed which allow assessment of the size of the effect, and their evaluation indicates something on the order of up to 14%. Therefore, for unambiguous non-invasive optical measurements, knowledge of the disturbance effect, and taking it into account will allow proper concentration determination. This treatment includes a comprehensive examination of identified side reactions which occur due to crossover ions between the electrodes.
... To understand the redox flow battery, requires understanding electrochemistry, electronic circuits, fluid dynamics, statistical and thermodynamic physics, material science, and mechanics. Background studies for vanadium redox flow batteries, our focus in this paper, may be found in variety of articles: membranes, [1][2][3][4][5][6][7][8][9][10][11][12] electrodes/materials/properties, [13][14][15][16][17] measures of performance, [18][19][20][21][22][23][24][25][26] fluid flow, cell aspects, [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63] battery control parameters, [64][65][66][67][68][69][70][71][72][73][74][75][76] electrolytes, [77][78][79][80][81][82][83][84][85][86][87][88] optical measurements, [89][90][91][92] and grids/systems. [93][94][95][96][97][98][99] There are also some reviews, 100-109 theses [110][111][112][113] and books. ...
Our focus in this treatment is a relatively novel approach to minimizing the fluid transfer imbalance between the negative and positive electrodes of a vanadium redox flow battery (VRFB) through the membrane, and determination of the horizontal/lateral change in pressure across each electrode, as well as the vertical pressure distributions. Underpinnings of the fluid transfer are the Darcy continuum equation. Here we develop analytical equations from the field equations affecting the fluid flow in the VRFB, which are very useful for controlling settings in battery stacks consisting of several cells.
The Vanadium redox flow battery (VRFB) has been intensively examined since the 1970s, with researchers looking at its electrochemical time varying electrolyte concentration time variation equations (both tank and cells, for negative and positive half cells), its thermal time variation equations, and fluid flow equations. Chemical behavior of the electrolyte ions has also been intensively examined. Our focus in this treatment is a completely new approach to understanding the physics, chemistry, and electronics of the VRFB. Here, we develop complete theoretical equations by an analytical treatment affecting the fluid flow in the VRFB as well as all other redox flow batteries, providing background derivations applicable for all of the fundamental concepts required to properly understand flow batteries. With these concepts presented, calculations are done to determine actual values for fluid velocity, strain rate, angular fluid velocity, angular momentum, rotational kinetic energy, and gravity effects on fluid velocity in a redox flow battery.
The Vanadium redox flow battery and other redox flow batteries have been studied intensively in the last few decades. The focus in this research is on summarizing some of the leading key measures of the flow battery, including state of charge (SoC), efficiencies of operation, including Coulombic efficiency, energy efficiency, and voltage efficiency, and energy density. New formulas are presented to allow calculation of energy density, under varying circumstances, including varying ionic electrolyte concentrations, terminal voltage, discharge times and cycle numbers, and electron exchange numbers in the redox chemical reactions. Effects of ionic crossover and side reactions are addressed, and it is shown which forms of energy density are robust against these additional undesirable chemical reactions.
The vanadium redox flow battery has been intensively examined since the 1970s, with researchers looking at its electrochemical time varying electrolyte concentration time variation equations (both tank and cells, for negative and positive half cells), its thermal time variation equations, and fluid flow equations. Chemistry behavior of the electrolyte ions have also been intensively examined too. In this perspective, all of the phenomena have been examined, unified and presented together with their physical chemistry shown in the appropriate equations. This is done by providing the field equations for the battery, which are electronic, electrochemical, chemical, physics of fluid dynamics, and thermal physics of heat transport, in character. They are interpreted in new analytical equations providing fundamental scientific insights, as well as allowing engineering and manufacturing assessments. Graphs of pressure trend in electrodes, power and temperature tables for electrode and current collector loss mechanisms are provided. Current density, concentration, electrostatic, and overpotential functional dependences in the electrodes are given.
The vanadium redox flow battery has been intensively examined since the 1970s. What is missing is a connection between the current‐overpotential Butler‐Volmer equation, which provides an extremely helpful starting point for analytical and numerical studies, and microscopic quantum mechanical behavior at the atomic level. Such a connection will allow further advancements beyond the macroscopic, though very useful and insightful, modeling already done in the literature. Here we show rigorously the connection between the Butler‐Volmer transfer coefficients, and the Marcus Gibbs free energy quantum mechanical parameters, and develop the equation directly in terms of the quantum mechanical parameters.
