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  • 1
    Electronic Resource
    Electronic Resource
    Screening of manganese dioxides for battery activity by thermogravimetric analysis (1971)
    Springer
    Journal of applied electrochemistry 1 (1971), S. 127-136 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Manganese dioxides which are suitable as cathodes for Leclanché cells need (a) a high MnO2 content and (b) battery activity. In this study it is shown that thermogravimetric analysis is a valuable method of screening manganese dioxides for battery activity. The parameter used is the temperature, under standard conditions, at which the rate of decomposition to Mn2O3 is maximum. This is called peak decomposition temperature. Battery activity, which was assessed from actual battery discharges, correlated well with peak decomposition temperature for the 20 manganese dioxides examined. A low peak decomposition temperature indicates high battery activity. As the total range of peak decomposition temperatures is only about 130°C, it is essential that the standard conditions are chosen to ensure decomposition of any one material over a narrow temperature range. For this reason the effects on sharpness of decomposition of gaseous environment, rate of gas flow, sample weight, particle size and rate of temperature rise have been examined. A significant improvement was effected by the use of an oxygen rather than a nitrogen environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01111859
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  • 2
    Electronic Resource
    Electronic Resource
    The cause of residual capacity in nickel oxyhydroxide electrodes (1980)
    Springer
    Journal of applied electrochemistry 10 (1980), S. 61-70 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Chemical analysis, X-ray diffraction and linear sweep voltammetry have been used to examine the cause of the secondary discharge plateau associated with the inefficient reduction of sintered plate NiOOH electrodes. The techniques confirm the presence ofβ-Ni(OH)2,β-NiOOH andγ-NiOOH in electrodes after failure at high rates. No evidence was obtained in support of the plateau arising from a new intrinsically less active compound. In disagreement with previous claims theγ-phase formed on overcharging was found to discharge as efficiently as theβ-phase. Inefficient discharge is considered to be caused by an insulating barrier layer ofβ-Ni(OH)2 between the charged active material and the current collector. The complex non-linear current-potential behaviour, exhibited by the secondary discharge plateau near −200 mV, is considered to be caused by the removal of Ni3+ or Ni3+ defects from the electronically conducting Ni(OH)2 prior to returning it to the poorly conducting divalent state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937339
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  • 3
    Electronic Resource
    Electronic Resource
    Corrigendum (1981)
    Springer
    Journal of applied electrochemistry 11 (1981), S. 401-401 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613961
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  • 4
    Electronic Resource
    Electronic Resource
    Studies concerning charged nickel hydroxide electrodes I. Measurement of reversible potentials (1980)
    Springer
    Journal of applied electrochemistry 10 (1980), S. 109-125 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Reversible potentials (E R) have been measured for nickel hydroxide/oxyhydroxide couples over a range of KOH concentrations from 0·01–10 M. It is shown that the couples derived from the parentα- andβ-Ni(OH)2 systems can be distinguished by the relative change in KOH level on oxidation and reduction. In the case of couples derived from theα-class of materials a dependence of 0·470 moles of KOH per 2e change is found compared with 0·102 moles of KOH per 2e change for theβ-class of materials. Couples derived from theα- andβ-Ni(OH)2 systems can be encountered in a series of ‘activated’ and ‘de-activated’ forms having a range of formal potentialsE 0 ′ . ‘Activated’. and ‘de-activated’β-Ni(OH)2/β-NiOOH couples are found to lie in the range 0·443–0·470 V whilstα-Ni(OH)2/γ-NiOOH couples lie in the range 0·392–0·440 V w.r.t. Hg/HgO/KOH. It is demonstrated for ‘de-activated’,β-Ni(OH)2/β-NiOOH couples thatE R is independent of the degree of oxidation of the nickel cation between states of charge of 25% and 70%. SimilarlyE R is constant for states of charge between 12% and 60% for ‘activated’α-Ni(OH)2/γ-NiOOH couples. The constant potential regions are considered to be derived from heterogeneous equilibria between pairs of co-existing phases both containing nickel in upper and lower states of oxidation. Differences inE 0 ′ between the ‘activated’ and ‘de-activated’ couples are considered to be related to the degree of order/disorder in the crystal lattice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937345
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  • 5
    Electronic Resource
    Electronic Resource
    On the manganese dioxide electrode. V. The evidence indicating the presence of two solid solutions in the range MnO2-MnO1·5 with γ-MnO2 as one end member (1982)
    Springer
    Journal of applied electrochemistry 12 (1982), S. 101-108 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract An examination of the literature has revealed that several of the properties of oxyhydroxides derived fromγ-MnO2 show a sharp change around the midpoint at MnO1.75. These include the lattice parameters, the activation energy for semiconduction, the magnetic susceptibility, the thermal behaviour and the electrical potential. Intermediate compounds have been observed by X-ray diffraction in the closely related systems ramsdellite/groutite and VO2/VOOH. It is suggested that for theγ-MnO2/δ-MnOOH system two solid solutions exist, one between MnO2 and MnO1.75 (e.g. Mn2O4H) and another between Mn2O4H and MnOOH. Ways in which the two solid solutions may arise involving different proton-electron filling mechanisms above and below the midpoint are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01112070
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  • 6
    Electronic Resource
    Electronic Resource
    The manganese dioxide electrode part XI: An X-ray diffraction study of materials produced by H insertion into an EMD (1991)
    Springer
    Journal of applied electrochemistry 21 (1991), S. 130-135 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Thirty-one samples of composition MnOOHr, where 0.1〈r〈1.0, were prepared under mild conditions by reacting a commercial electrodeposited manganese dioxide (EMD) with xylene, acetone, cinnamyl alcohol or combinations thereof. Although the X-ray pattern reflected the expected dilation of the crystal structure in the region 0.1〈r〈0.8 the attainment of an H insertion level of MnOOH0.8 without the emergence of additional peaks is a new finding. The expansion was nearly isotropic and careful examination of peak positions and intensities indicated changes in behaviour at aboutr=0.25 and 0.45. Another finding was the ability of inserted H to migrate across the boundaries of nominally dry powders in the region 0.1〈r〈0.8. In the regionr〉0.8 expansion was clearly anisotropic and as a consequence new diffraction peaks emerged and some of the peaks present at lower H insertion levels were substantially reduced in intensity. A particularly important observation was the restricted mobility shown by inserted H in the end-product MnOOH as this has implications for the performance of EMD in batteries. The X-ray diffraction pattern of the end-product was dissimilar to α- and γ-MnOOH in important respects and a previous suggestion that it is called δ-MnOOH seems preferable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01464293
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  • 7
    Electronic Resource
    Electronic Resource
    Discharge performance of electrodeposited manganese dioxides in Leclanché cells (1971)
    Springer
    Journal of applied electrochemistry 1 (1971), S. 45-52 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodeposited manganese dioxide is finding increasing use as the cathode in high performance Leclanché cells. In this study a number of commercial and pilot plant materials together with experimental variants were examined in Leclanché R.20 size cells and found to have widely different performances on a simulated motor discharge. The initial X-ray diffraction diagrams of the manganese dioxides, viewed in order of decreasing discharge performance, show a gradual diminution of theγ phase peak and the emergence of aβ phase peak. X-ray diffraction thus provides a means of recognizing a preferred electrodeposited manganese dioxide for the simulated motor discharge.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615746
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  • 8
    Electronic Resource
    Electronic Resource
    Studies concerning the growth of cadmium dendrites. II. Morphology in acidic media (1983)
    Springer
    Journal of applied electrochemistry 13 (1983), S. 765-773 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The morphology of cadmium deposits formed during potentiostatic deposition onto etched cadmium substrates in a range of cadmium sulphate solutions with 0.5 mol dm−3 sulphuric acid as supporting electrolyte has been investigated. The deposit morphology and induction time was found to be both concentration and overpotential dependent. At 10−1 mol dm−3 CdSO4 for an overpotential range −20 to −80 mV, large crystalline aggregates were observed and large dendrites resulted after longer deposition times. The induction time was less than 1 min and the current time curves linear, indicating instantaneous rather than progressive initiation. At 10−2 mol dm−3 CdSO4 the morphology varied from fine, 2D-fern dendrites atη=−75 mV to needle dendrites atη=−150 mV. The morphology at 10−3 mol dm−3 CdSO4 closely resembled that at 10−2 mol dm−3 CdSO4 but, showed finer structural detail with less filling in of the main skeletal structure. The induction time was an order of magnitude greater at 10−3 mol dm−3 CdSO4 than at 10−2 mol dm−3 CdSO4, and the time taken to grow dendrites of the same length was also increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615826
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  • 9
    Electronic Resource
    Electronic Resource
    Studies concerning the growth of cadmium dendrites. I. Morphology in alkaline media (1983)
    Springer
    Journal of applied electrochemistry 13 (1983), S. 751-764 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The morphology of cadmium dendrites formed during potentiostatic electrodeposition onto nickel and cadmium substrates from cadmate solutions in alkaline supporting electrolyte has been investigated. The morphology is potential dependent for deposition under convective diffusion conditions to a nickel substrate. For 1.05×10−4 mol dm−3 Cd(OH) 4 2− /30% KOH solutions, 2D- fern dendrites are observed at an overpotential of −150mV, needle dendrites at −200 mV, and large ‘filled-in’ fern dendrites at −300 mV. Similar results were found at the higher concentration, 2.4×10−4 mol dm−3 Cd(OH) 4 2− /50% KOH, but the time taken to grow an equivalent morphology and length were reduced in proportion. Crystalline aggregate dendrites were observed on a cadmium substrate in 1.05×10−4 mol dm−3 Cd(OH) 4 2− /30% KOH, becoming more crystalline and well defined with increase in overpotential. A significant induction time of the order 8 h was observed for all deposition onto stationary nickel and cadmium wires. Under the well-defined diffusion conditions at a rotating nickel disc electrode only one morphology, namely small ferns, was observed over a wide range of overpotentials. The current-time behaviour is presented, and the current is shown to have a (time)2 dependence, indicative of progressive nucleation of dendrites. The induction time, indicated approximately by the current minima, had decreased significantly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615825
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  • 10
    Electronic Resource
    Electronic Resource
    Studies concerning the growth of cadmium dendrites III. Theoretical treatment (1984)
    Springer
    Journal of applied electrochemistry 14 (1984), S. 187-196 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The growth of dendritic cadmium during electrodeposition in alkaline and acid media has been investigated. By combining electrochemical data with measurements taken from scanning electron micrographs, a selection of which have been presented in parts I and II, it is shown that the theoretical approach of Diggle, Despic and Bockris [5] is in good agreement with the experimental results. The total current versus time behaviour for the alkaline system can be predicted using the exponential limiting form of the equations with the assumption that the dendrites approximate to rectangular rods and follow a first order progressive initiation law. The very different behaviour in the acidic media is predicted from the linear limiting form of the equations with the assumption that the dendrites approximate to cylindrical rods and follow an instantaneous initiation law.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618737
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