Factors affecting the internal resistance of silver/silver molybdate/iodine cells

✍ Scribed by A.K. Arof

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 267 KB
• Volume: 45
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/0378-7753(93)87016-v

✦ Synopsis

A silver molybdate glass with the tool% stoichiometry of 60AgI-20Ag20--20MoO3 is prepared by liquid nitrogen temperature quenching of the melt. The glassy nature of the phase has been confirmed by powder X-ray diffraction. The conductivity of the glass from impedance spectroscopy is of the order 10 -3 S crn -1 at 300 K. The phase is an electrolyte ahd has been used to fabricate several iodine/silver electrochemical cells in which silver is mixed in different proportions with the solid electrolyte for the anode of the cells. The cathode consists of a fixed ratio of iodine, electrolyte and carbon. It is found that, if the cathode disc is placed over the electrolyte surface of the anode/electrolyte disc and clamped between two copper current collectors, the cell with a 1:1 weight ratio of silver powder and the electrolyte shows the lowest internal resistance. A second cell has been fabricated with this anode composition, but the anode, electrolyte and cathode are pressed together to form a single solid disc so as to eliminate cathode/electrolyte interfaeial resistance that also contributes to the total internal resistance of the cell. For the cells with a composition of 1:1 silver powder and electrolyte weight ratio, the internal resistance of the cell decreases from 2.3 kl'~ when the cathode and anode/electrolyte layers of the cell are pressed separately to 0.15 kO for a cell with the anode, electrolyte and cathode pressed together. The value of 0.15 k~ is in reasonable agreement with the bulk resistance of the electrolyte as obtained from the impedance plot.