Electrical Conductivity of PbO and Discharge Property of Thin Film PbO₂/PbO/Pb Solid Cell

Abstract

In order to develop all solid state electrochemical cells, thin film PbO₂/PbO/Pb solid cells were produced. All the constituents were systematically deposited on a glass substrate by reactive sputtering and vacuum evaporation. The discharge properties of the solid cells were improved by the addition of a uni-valent impurity such as sodium or potassium to the PbO electrolyte; the electromotive force of the solid cell using PbO-3.13 mass % Na₂CO₃ as the electrolyte reached 69% of the theoretical value during discharge. On the other hand, the presence of a tri-valent impurity such as antimony or bismuth in the electrolyte decreased the electromotive force. The electrolytes with the uni-valent impurities had a lower electronic conductivity compared with the impurity-free PbO, while the electrolytes with the tri-valent impurities had a higher one. These results were interpreted by a point defect model of oxygen ion vacancies which are the dominant defects in the PbO electrolyte; the uni-valent impurities increase the concentration of the vacancies to improve the ionic conductivity of the electrolyte. Also, the discharge reactions at both interfaces of PbO₂/PbO and PbO/Pb were determined by X-ray photoelectron spectroscopy.