ISSN:
1572-8838
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Elektrotechnik, Elektronik, Nachrichtentechnik
Notizen:
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.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01132440
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