The Electrochemical Behaviour of Manganese(II)‐Hydroxide and Manganese(II)‐Hydroxide/Aluminum Hydroxide

Bauer, J.; Buss, D. H.; Glemser, Oskar

doi:10.1002/bbpc.19850891011

Cited by 7 publications

(2 citation statements)

References 7 publications

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“…However, there may exist a narrow concentration "window" in which carbide formation is possible. This phenomenon has been studied in detail for tantalum carbide (5). A similar situation may exist for titanium (6).…”

Section: Introductionmentioning

confidence: 67%

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The Electrochemical Behavior of Positive Cobalt/Aluminum and Cobalt/Iron Hydroxide Electrodes

Bauer

Buss

Harms

et al. 1990

J. Electrochem. Soc.

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Doping ~-Co(OH)2 with M 3 § (A13 § Fe 3 § ions by coprecipitation of the nitrate or sulfate salts at pH = 12.5 leads to compounds in which the usual electrochemical inertness of CoOOH is overcome. Products of molar ratio Co:M = 4:1 have the highest charge capacity. They crystallize in the double layer structure of the pyroaurite type, consisting of Co/M hydroxide cations [Co4M(OH)~0]-, M = A1, Fe and anion interlayers [X-, nH20]-X = NO3-, SO42-. The pyroaurite structure favors the formation of various hydrogen bonds. These hydrogen bonds facilitate both the proton availability, which increases as the anion is changed from NO3-to SO42-(as indicated by the increase of capacity and stability of cycles), and also the electrochemical oxidation of cobalt, leading to a maximal oxidation state of + 3.7. The iron compounds are not pure; in addition to the pyroaurite phase, they contain some ~-Co(OH)2, which lowers the capacity.In contrast to the nickel hydroxide electrode (1), there have been very few experimental investigations of the cobalt hydroxide electrode; this is probably a consequence of its irreversibility when acting as a positive electrode. The product formed on charging is CoOOH, which is nearly inert electrochemically and thus practically unable to charge and discharge. Oxidation states of cobalt exceeding +3 have been discussed in earlier thin layer studies of the cobalt hydroxide electrode (2, 3). The discharge of such products appeared possible but further studies were not reported.Partial substitution of Co s § ions by A13 § ions [up to -40 mole percent (m/o) A1] into the layer lattice of ~-Co(OH)2 by coprecipitation of the nitrate salts leads to various products. In one of these cobalt could be electrochemically oxidized in alkaline solution to an oxidation state of +3.7, as we described recently (4). The species with the ratio Co:A1 = 4:1 in Co~l(OH)10NO3 has striking electrochemical properties: of all investigated products it has maximal discharge capacity and can be used as a reversible positive electrode (4). We have continued and extended our studies in this field and prepared, corresponding to the above mentioned products, Co/A1 samples of the ratio Co:A1 = 4:1 from their sulfate salts and Co/Fe species of the ratio 4:1 from their nitrate and sulfate salts. ExperimentalThe compounds were prepared according to former reports (4, 5, 7, 8) by computer-controlled precipitation of cobalt(II)-and aluminum(III)-or iron(III)-salt solutions with potassium hydroxide solutions. Corresponding to former investigations in this field (5), the precipitations were carried out at, or as near as possible to, the isoelectric point of solid (IEPS). Parks (6), on the basis of an empirical equation, calculated the IEPS of Co(OH)2 at pH = 11.2. For Co/Fe precipitates we preferred pH = 12.5; and for Co/A1 precipitates pH = 9.0, bearing in mind the solubility of aluminum hydroxide in more highly concentrated potassium hydroxide solutions. Furthermore, the metal salt solutions had to be acidified to pH=<2, to exclude hydrox...

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Section: Introductionmentioning

confidence: 67%

“…The products were characterized electrochemically by measuring the specific charge (q) in mAh/g in a test cell (5). The positive electrode was a mixture of 3g substance and 7g nickel powder placed in a tube fitted with nickel gauze.…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

The Electrochemical Behavior of Positive Cobalt/Aluminum and Cobalt/Iron Hydroxide Electrodes

Bauer

Buss

Harms

et al. 1990

J. Electrochem. Soc.

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Computergesteuerte Fällung von Metallhydroxiden und -oxidaquaten – Herstellung von Braunstein einheitlicher Partikelgröße

1985

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Bis heute konnten ca. zwanzig polycyclische Organophosphane isoliert und charakterisiert['S2] sowie einige weitere spektroskopisch nachgewiesen ~e r d e n~' -~' .Wir konnten jetzt Bis(2,4,6-tri-tert-butylphenyl)bicyclotetraphosphan 1, ein Derivat des einfachsten bicyclischen Phosphans, synthetisieren. 1 entsteht neben Bis(2,4,6-tri-tert-butylpheny1)diphosphen 214] bei der Einwirkung von 2,4,6-Tn-tert-butylphenyllithium und l-Brom-2,4,6-tri-tert-butylbenzol auf weiBen Phosphor. Damit ist es erstmals gelungen, weiBen Phosphor so umzusetzen, daB nur eine Bindung des P4-Tetraeders ge6ffnet wird. 4 R L i + 4 R B r + 3 P4 -2 R2P4 + 2 R2P2 + 4 L i B r 1 2

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Computer‐Controlled Precipitation of Metal Hydroxides and Hydrous Oxides—Preparation of Manganese Dioxide Having Uniform Particle Sizes

Buss

Schaumberg

Glemser

1985

Angew. Chem. Int. Ed. Engl.

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1 shows two multiplets, 6= -272 (bridgehead P atoms) and 6= -130, while the 'H(3'P)-NMR spectrum contains two singlets at 6= 1.27 (4-tBu) and 1.74 (2,6-tBu) as well as a multiplet at 6=7.0. These findings are consistent with the results of an X-ray structure analysis (Fig. l).I5' Eggenstein-Leopoldshafen 2, on quoting the depository number CSD-51 578, the names of the authors, and the full citation of the journal. 161 E. Niecke, R. Ruger, B. Krebs, Angew. Chem. 94 (1982) 553; Angew.Chem. I n t . Ed. Engl. 21 (1982) 544.

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The Electrochemical Behaviour of Manganese(II)‐Hydroxide and Manganese(II)‐Hydroxide/Aluminum Hydroxide

Cited by 7 publications

References 7 publications

The Electrochemical Behavior of Positive Cobalt/Aluminum and Cobalt/Iron Hydroxide Electrodes

The Electrochemical Behavior of Positive Cobalt/Aluminum and Cobalt/Iron Hydroxide Electrodes

Computergesteuerte Fällung von Metallhydroxiden und -oxidaquaten – Herstellung von Braunstein einheitlicher Partikelgröße

Computer‐Controlled Precipitation of Metal Hydroxides and Hydrous Oxides—Preparation of Manganese Dioxide Having Uniform Particle Sizes

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