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  • 1980-1984  (10)
  • 1975-1979  (2)
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Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effects of charge rate and cycling on the morphology of Cd and Cd(OH)2 in sintered plate electrodes (1976)
    Springer
    Journal of applied electrochemistry 6 (1976), S. 431-444 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Optical and scanning electron microscopy have been used to study the growth and redistribution of Cd and Cd(OH)2 in sintered plate electrodes as a function of charge rate and cycle number. As expected, the growth of both components was found to increase with increasing cycle number and decreasing charge rate. Because the deposits, particularly after extended cycling, always contained appreciable quantities of Cd metal in both the charged and discharged state, the sizes of Cd(OH)2 crystallites were difficult to quantify. High charge and discharge rates promoted greater aggregation and redistribution of active material towards the electrode edge. This resulted in a considerable decrease in the available pore volume per unit mass of active material and in extreme cases to localized pore blockage. The trapping of Cd metal by highly crystalline, unchargeable hexagonal platelets of (δ-Cd(OH)2 resulted in about 50% of the active material becoming obsolete after 100 cycles at high charge and discharge rates. At this stage only the finely divided Cd metal in the electrode interior continued to function. Low charge rates gave deposits of more uniform size and distribution but these contained a high percentage of large Cd particles which discharged less efficiently than those produced at the high charge rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616543
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  • 2
    Electronic Resource
    Electronic Resource
    Cyclic charge-discharge behaviour of sintered plate and planar cadmium electrodes (1976)
    Springer
    Journal of applied electrochemistry 6 (1976), S. 107-118 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The cyclic charge-discharge behaviour of sintered plate and planar cadmium electrodes has been studied using galvanostatic and potentiostatic sweep techniques. The cycling inefficiency of sintered electrodes reflected more the discharge process as shown by analytical monitoring of cadmium levels before and after charge. The effect of discharge rate on cycling efficiency was also investigated. Open-circuit recovery experiments indicated that a critical potential was reached at which passivation occurs subsequent to which a plateau region was observed for sintered electrodes. Potentiostatic sweeps on partially discharged electrodes and X-ray diffraction suggested the formation of a nickel-cadmium alloy during charge. Comparison of cyclic sweeps on sintered and planar electrodes showed the distribution effects of active material through the sinter and also the improved charge acceptance of sintered electrodes. Cyclic sweeps on planar electrodes indicated the involvement of forms of cadmium of different activity, whilst cathodic sweeps after prolonged retention at potentials anodic to passivation indicated a more complex reduction route.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615375
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  • 3
    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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  • 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
    Studies concerning charged nickel hydroxide electrodes. II. Thermodynamic considerations of the reversible potentials (1980)
    Springer
    Journal of applied electrochemistry 10 (1980), S. 127-141 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper the thermodynamics of mixing are applied to account for the independence of the discharge potential of the nickel hydroxide electrode as a function of nickel oxidation state. The constant potential region is considered to arise from the formation of a pair of co-existing solid solutions having a composition predetermined by the magnitude of the interactions between the oxidized and reduced species. From considerations of the excess-energy terms, it can be shown for a symmetrical potential/ composition profile, that the constant potential region is identical with the standard potentialE 0. The influence of asymmetry on the changes inE 0 are discussed. Consideration has also been made of the influence of dissociation of oxidized and/or reduced species on the potential determining equations. The removal of n-type defects from the nickel(II)-rich phase on discharge is considered to be responsible for the observed secondary discharge plateau at potentials ∼ 300 mV more cathodic than normal. This non-equilibrium behaviour can be explained in terms of a mixed pn-semiconducting material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00937346
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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Studies concerning charged nickel hydroxide electrodes IV. Reversible potentials in LiOH, NaOH, RbOH and CsOH (1981)
    Springer
    Journal of applied electrochemistry 11 (1981), S. 517-523 
    Details
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The variation of reversible potential Er with log amoh and $$a_{H_2 O} $$ has been studied for several nickel hydroxide/oxyhydroxide couples in various alkali hydroxides. Both ‘activated’ and ‘deactivated’ β-phase couples show only a small dependence ofE r with logmoh (or $$a_{H_2 O} $$ where known) in LiOH, NaOH, RbOH and CsOH electrolytes. The change in MOH content on oxidation/reduction is found to be about 0.1 mol MOH per two-electron transfer and is the same as found previously in KOH. These results confirm that the bulk oxidized β-phase lattice is devoid of alkali cation although a small quantity may be adsorbed by the surface. On the other hand both ‘activated’ and ‘deactivated’ α/γ-phase couples show a marked dependence of ∼ 0.45 mol MOH per two-electron transfer in LiOH, NaOH and RbOH (at concentrations 〉 0.5 m), also in good agreement with earlier data for KOH. On the basis of these results a general stoichiometry can be inferred for the γ-phase, namely M0.32NiO2 · 0.7H2O where M=Li+, Na+, K+ or Rb+. Measurements imply that the Cs+ ion or the Rb+ ion at low concentration (〈0.5 m) do not enter the interlayer structure of the γ-phase. This behaviour is thought to be related to the low Rb-O and Cs-O bond strengths afforded by the γ-phase structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01132440
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