Experiments on the Discharge Mechanism of the Manganese Dioxide Electrode

Vosburgh, W. C.; Lou, Pao‐Soong

doi:10.1149/1.2428121

Cited by 20 publications

(10 citation statements)

References 17 publications

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“…The Overpotential.--It has been assumed previously that in the early part of the discharge of electrodeposited ~-MnO2 electrodes in ammonium salt electrolyte at pH 7-8 the following reaction takes place (12,13).…”

Section: Discussionmentioning

confidence: 99%

“…Diffusion must be involved, but whether it is rate-determining is not clear. There is evidence that the amount of lower oxide on the surface is a small fraction of the total (13).…”

Section: July 1961mentioning

confidence: 99%

“…Part of this paper was prepared for delivery before the Columbus Meeting, Oct. [9][10][11][12][13] 1959. Based on a thesis submitted to tbe graduate faculty of Duke University in partial fulfillment of the reauirements for the degree of Doctor of Philosophy by H. B.…”

Section: Acknowledqmentmentioning

confidence: 99%

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The Discharge Mechanism of Certain Oxide Electrodes

Mark

Vosburgh

1961

J. Electrochem. Soc.

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The discharges of PbO~, TiO~, and TLOz electrodes were studied and are compared with similar discharges of the MnO~ electrode. The overpotentials of PbO~ and TiO2 electrodes at small current densities are linear functions of the current density, but TLO~ is like MnO~ in having a square-root relation. It is considered that the first step in the electrode reaction is reduction to a lower oxide or hydroxide and that the subsequent disposal of this is rate-determining. The square-root relation is correlated with the existence of an unstable valence state between the initial and final products. A few experiments with Ce(OH), and SnO~ electrodes were carried out, but these were less satisfactory as current-producing electrodes than the others.

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Section: Discussionmentioning

confidence: 99%

“…Diffusion must be involved, but whether it is rate-determining is not clear. There is evidence that the amount of lower oxide on the surface is a small fraction of the total (13).…”

Section: July 1961mentioning

confidence: 99%

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The Discharge Mechanism of Certain Oxide Electrodes

Mark

Vosburgh

1961

J. Electrochem. Soc.

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“…In an attempt to gain an understanding of the discharge mechanism of manganese dioxide many studies have been conducted. The studies by Vosburgh et al [1][2][3][4][5][6][7][8][9] represent the first steps in gaining an understanding of this discharge mechanism. These authors suggested that electrons from an external circuit combine with protons from the electrolyte near the surface of the solid manganese dioxide to reduce Mn 4+ ions to Mn 3+ , and also to protonate O 2− to form OH − ions.…”

Section: Introductionmentioning

confidence: 99%

Surface characterisation of chemically reduced electrolytic manganese dioxide

Malloy

Donne

2008

Journal of Colloid and Interface Science

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“…Reduction of ␥-MnO 2 .-Combined with the initial work by Vosburgh et al, [17][18][19][20][21][22][23][24][25] the investigations reported by Kowaza et al [26][27][28][29][30][31][32] represent the first serious studies into the ␥-MnO 2 reduction mechanism. One of the key findings by Kozawa et al was the presence of two distinct stages in the reduction of ␥-MnO 2 .…”

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confidence: 99%

Porosity Changes during Reduction of γ-MnO[sub 2] for Aqueous Alkaline Applications

Malloy

Donne

2008

J. Electrochem. Soc.

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In this work a structural and porosity analysis of a series of chemically reduced electrolytic manganese dioxide ͑EMD͒ samples has been carried out. EMD, or ␥-MnO 2 , for use in aqueous alkaline cathodes possesses an orthorhombic unit cell that progressively increases in size as reduction continues. This unit cell expansion is nonuniform, with dimensional changes being different in all three dimensions ͑b 0 Ͼ a 0 Ͼ c 0 ͒. The unit cell expansion is the direct result of the reduction process, with the discharge products ͑Mn 3+ and OH − ͒ being larger than the corresponding ions in the host lattice ͑Mn 4+ and O 2− ͒. Gas adsorption isotherms on the same series of reduced EMD samples demonstrated that the Brunauer-Emmett-Teller surface area decreased considerably over the entire discharge compositional range. The calculated pore size distribution showed that microporosity was eliminated with reduction, but the mesopore volume increased. The origin of these changes in porosity is discussed in terms of the structural expansion, as is their effect on electrochemical performance.Background.-Electrolytic manganese dioxide ͑EMD͒ is a porous material 1-3 with Brunauer-Emmett-Teller ͑BET͒ surface areas ranging from 10 to 100 m 2 /g, although commercially produced materials are typically in the range 25-35 m 2 /g. These large BET surface areas are the result of the EMD containing a large amount of internal porosity, covering a broad range of pore sizes from micro-, through meso-, to macropores. 1 Changes to the conditions used to manufacture EMD alter this pore size distribution, and given the wide range of BET surface areas that an EMD can possess, the variation in pore size distribution can be substantial. The implications of this on the electrochemical behavior of the EMD are also quite significant, given that not all of this porosity may be accessible to the electrolyte, meaning that the electrochemically active surface area is almost always going to be different compared to the BET surface area. 2 Manganese dioxide has been used as the cathode-active material in primary batteries for many decades. EMD is the active material of choice, and within an alkaline cathode it is mixed intimately with an electronic conductor such as graphite and an ionic conductor such as a concentrated aqueous KOH solution. 2-4 This electrode configuration generates a high surface-area-to-volume ratio, which results in a large electrolyte-electrode interface, thus allowing its efficient use as a cathode. 2 As performance of the alkaline EMD cathode is a limiting factor for alkaline batteries at high drain rates, 2 gaining a better understanding of how electrode features such as porosity effect mass-transport phenomena occurring near this interface is desired. Despite many years of use, and research into its behavior, there are still many features of manganese dioxide behavior that need clarification. One of these is the role of manganese dioxide porosity, which is the subject of this work.

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Experiments on the Discharge Mechanism of the Manganese Dioxide Electrode

Cited by 20 publications

References 17 publications

The Discharge Mechanism of Certain Oxide Electrodes

The Discharge Mechanism of Certain Oxide Electrodes

Surface characterisation of chemically reduced electrolytic manganese dioxide

Porosity Changes during Reduction of γ-MnO[sub 2] for Aqueous Alkaline Applications

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