The effect of gel structure on ionic conductance and capacitor impedance

The aim of this work was the determination of the effects of gelling the electrolytes used in electrolytic capacitors of the type Ta/Ta2O5/gel electrolyte/counter electrode. The investigation was divided between two main areas: firstly, the ionic conductivity of gel electrolytes was examined using Pt/Pt black electrodes; secondly, the influence of various electrolytes on the properties of tantalum and Ta/Ta2O5 electrodes, and on the electrolytic capacitors was examined. The conductivity of a series of gels prepared from fumed silica and 40% sulphuric acid showed a non-linear dependence on silica content, but was sensitive to the method of preparation. A standard mixing technique was developed and the reproducible conductivity of gels prepared by this method showed a linear decrease with increasing silica content. [Continues.]