Evaluation of the characteristics of exchange reactions

Farr, J.P.G.; Hampson, N.A.

doi:10.1016/0022-0728(67)80046-9

Cited by 87 publications

(42 citation statements)

References 3 publications

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Section: N2mentioning

confidence: 99%

“…It is generally accepted that the anodic zinc dissolution forms zincate ions as follows Zn + 4 OH-~-Zn(OH)~-+ 2e [2] Often the reaction orders of zincate and hydroxide ions obtained from the anodic portion of a polarization curve are different from those obtained from the cathodic portion. The reaction order of hydroxide varies from 1.0 to 3.6, and that of zincate ions changes from 0.65 to 0.9, and the exchange current density varies from 0.5 to 400 mA/cm 2 (13)(14)(15)(16). For engineering purposes, it may be reasonable to use the Butler-Volmer equation as the overall kinetic expression.…”

Section: Chemistry and Electrochemistrymentioning

confidence: 99%

“…A charge balance for the currents (ia and i2) and the electrochemical reaction (reaction [2]) yields the equation where ja is the transfer current per unit volume of the electrode due to reaction [2], which can be expressed by a Butler-Volmer equation (15,16) 9 r/c= p…”

Section: N2mentioning

confidence: 99%

“…The potential in the solid phase of the electrode changes according to Ohm's law ia = I -i2 = -~(1 -~1) l+v 0(~a [13] bX where I is the applied current density, +a is the potential in the solid phase, ia is the current density in the solid phase, and cr(1 -el) 1 § represents the effective electrode conductivity with el representing the porosity related only to metallic zinc. A charge balance for the currents (ia and i2) and the electrochemical reaction (reaction where ja is the transfer current per unit volume of the electrode due to reaction [2], which can be expressed by a Butler-Volmer equation (15,16) 9 r/c= pwhere a, is the surface area of metallic zinc per unit volume of the electrode which is assumed here to be proportional to (1 -el)where ~ is a surface effect factor, ao and e ~ are the initial specific surface area and porosity of the zinc electrode, respectively. Since zinc dissolution is due to the electrochemical reaction, e~ changes according to the equation 0El Yzn .…”

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Mathematical Modeling of a Primary Zinc/Air Battery

Mao

White

1992

J. Electrochem. Soc.

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The mathematical model developed by Sunu and Bennion has been extended to include the separator, precipitation of both solid ZnO and K2Zn(OH)4, and the air electrode, and has been used to investigate the behavior of a primary Zn-Alr battery with respect to battery design features. Predictions obtained from the model indicate that anode material utilization is predominantly limited by depletion of the concentration of hydroxide ions. The effect of electrode thickness on anode material utilization is insignificant, whereas material loading per unit volume has a great effect on anode material utilization; a higher loading lowers both the anode material utilization and delivered capacity. Use of a thick separator will increase the anode material utilization, but may reduce the cell voltage.Zinc is used widely as an anode in many alkaline batteries, such as Zn]Ni and Zn/Air. Optimum designs of these batteries depend on understanding the zinc chemistry and electrochemistry in alkaline solution and the mass-transport processes in the battery during charge and discharge. While the former has been extensively investigated experimentally, only a few mass-transport models have been presented. Choi, Bennion, and Newman (1) presented a mathematical model of a secondary Zn/AgO battery for analysis of the material redistribution in the battery during charge and discharge. Their model includes convective flow caused primarily by osmosis and electro-osmosis forces. It was found that the convective flow is primarily responsible for the nonuniform zinc distribution on the electrode plate. The validity of their conclusions was verified partially by their experiments that showed virtually no zinc redistribution when the convective flow was minimized (2). Sunu and Bennion (3) developed a comprehensive model of a porous zinc electrode to investigate the electrode phenomena in the direction perpendicular to the projected electrode surface. In their model, the masstransport equations were developed based on concentrated ternary electrolyte theory. Three electrode failure mechanisms (namely, depletion of hydroxide ions, pore plugging by zinc oxide, and surface passivation) were identified by analyzing the model simulations. The validity of their model was verified by good agreement between their model predictions and experimental data of porosity and zinc oxide distributions (4). Their model was used later by Isaacson et al. (5) and Miller et al. (6) to investigate zinc movement in both the vertical and parallel directions to the electrode surface. Good agreement was obtained by Isaacson et al. (5) between their model predictions and experimental chronopotentiometric data.It should be noted that all previous mathematical models were used to study secondary batteries and that the model verification was conducted using a half cell or a ZnNiOOH cell. Previous modeling efforts were focused on the zinc electrode; and, consequently, the concentration distributions in the separator were neglected. Although the findings from such resea...

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Section: N2mentioning

confidence: 99%

Section: Chemistry and Electrochemistrymentioning

confidence: 99%

Section: N2mentioning

confidence: 99%

mentioning

confidence: 99%

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Mathematical Modeling of a Primary Zinc/Air Battery

Mao

White

1992

J. Electrochem. Soc.

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“…The electrochemical behaviour of zinc in alkaline aqueous media has been the subject of a relatively large number of investigations (1)(2)(3)(4)(5)(6) due to the importance of this system for both industrial electrodeposition processes and high density electrical batteries. With regard to the latter, corrosion is one of the principal factors that restricts the application of the zinc-zincate system as an efficient energy source over very long periods of time.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the diffusion coefficient of the zincate ion using a rotating disk electrode

Pessine¹,

Agostinho²,

Chagas³

1986

Can. J. Chem.

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ELISABETE JORGE PESSINE, SILVIA M. L. AGOSTINHO, and HBLIO C. CHAGAS. Can. J. Chem. 64, 523 (1986). Using a rotating Hg-film disc electrode, the diffusion coefficient of the zincate ion in a 1-4 M aqueous solution of NaOH was measured. Experiments covered a temperature range from 25 to 40°C. The experimental results are in agreement with the predictions of the Stokes-Einstein theory for diffusivity. The obtained Stokes radii decrease with increasing alkali concentration, but the ratio D q / T is reasonably constant within the whole range of temperature investigated.

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Mechanisms of Stepwise Electrode Processes on Amalgams

Losev

1972

Modern Aspects of Electrochemistry No. 7

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Evaluation of the characteristics of exchange reactions

Cited by 87 publications

References 3 publications

Mathematical Modeling of a Primary Zinc/Air Battery

Mathematical Modeling of a Primary Zinc/Air Battery

Evaluation of the diffusion coefficient of the zincate ion using a rotating disk electrode

Mechanisms of Stepwise Electrode Processes on Amalgams

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