Engineering Analysis of Shape Change in Zinc Secondary Electrodes: II . Experimental

Choi, King Wai; Hamby, Drannan C.; Bennion, Douglas N.; Newman, John

doi:10.1149/1.2132658

Cited by 46 publications

(45 citation statements)

References 6 publications

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Section: N2mentioning

confidence: 99%

“…However, several reaction mechanisms have been proposed by different researchers, and, unfortunately, agreement about a kinetics expression has not been obtained. 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).…”

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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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 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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“…Dendritic deposits, as well as passivation effects during the discharge process are challenges arising from concentration depletion or oversaturation in the electrolyte and the subsequent precipitation of zincate ions at the electrode. Likewise, an unequal current distribution during operation induces a non‐uniform distribution of the deposition of zinc species . It has been shown previously that the dissolution of zinc within the electrolyte induces an increase of the density of the electrolyte.…”

Section: Introductionmentioning

confidence: 99%

Multiscale Structured Particle‐Based Zinc Anodes in Non‐Stirred Alkaline Systems for Zinc–Air Batteries

et al. 2018

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Primary zinc–air batteries are well established in the commercial market, but secondary zinc–air batteries still suffer from challenging problems. Multiple charge and discharge cycles result in zinc density migration and the formation of passivating by‐products, which can ultimately change the shape of the zinc anode. This work focuses on the use of zinc particles in combination with highly structured current collectors in a cell with a stagnant alkaline electrolyte. Copper weave and copper foam were used as current collectors. The influences of the zinc particle size, the mass loading and the macroscopic structure of the anodes were characterized. Highly structured electrode designs led to improved discharge and cycling performances. Due to the increased active surface area, the electrodes take advantage of highly distributed zinc deposits. The results reveal that the use of multiscale structures within the zinc anode can be beneficial for further applications.

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Metal/air batteries: the zinc/air case

Haas

Holzer

Müller

et al. 2010

Handbook of Fuel Cells

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Metal/air batteries provide high specific energy and consist of inexpensive and environmentally benign materials. They have begun to penetrate the market of portable power sources and offer great promise for transportation applications. In this review, we first discuss the basic aspects of metal/air batteries, then concentrate on the Zn/air system as the most promising metal/air battery. The Zn/air systems have important advantages due to the excellent electrochemical properties of metallic zinc, which include a high overpotential towards hydrogen evolution. This implies that Zn/air batteries with aqueous electrolytes can be electrically recharged, that zinc from spent batteries can be regenerated by electrolysis in aqueous systems, and that mechanically rechargeable Zn/air batteries (arrangements resembling fuel cells) can be realized with aqueous electrolytes. Advances in the development of Zn/air battery components are reviewed and the state of the art of electrically and mechanically rechargeable Zn/air systems is described in detail. An overview of industrial developments in zinc/air battery systems and the nominal performance of available products is included. Practical specific energies in the range of 90–120 Wh kg −1 have been reported for electrically rechargeable Zn/air batteries, about twice as much for mechanically rechargeable systems. Significant progress has been made concerning the cyclability of the electrically rechargeable Zn/air system, by utilizing pasted zinc electrodes and graphitized carbon for the bifunctional oxygen diffusion electrodes. Cycle lives in the range of 200–450 cycles have been achieved.

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Engineering Analysis of Shape Change in Zinc Secondary Electrodes: II . Experimental

Cited by 46 publications

References 6 publications

Mathematical Modeling of a Primary Zinc/Air Battery

Mathematical Modeling of a Primary Zinc/Air Battery

Multiscale Structured Particle‐Based Zinc Anodes in Non‐Stirred Alkaline Systems for Zinc–Air Batteries

Metal/air batteries: the zinc/air case

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