The Rate Limiting Mechanism in Li / I 2 (P2VP) Batteries: I . Effect of Discharge Rate on the Morphology and Dimensions of the Cell Components

Abstract

As part of an effort to delineate the rate limiting mechanism in (P2VP) batteries with pelletized cathodes, scanning electron microscopy was performed on cells fully discharged across 20, 5, and 1 kΩ resistors at room temperature. This required the development of a specimen preparation technique due to the mechanical and chemical properties of the cell components. The dependence of the dimensions and morphology of the cell components upon discharge rate was determined. A strong dependence of the electrolyte layer morphology upon discharge rate was observed and related to the increased polarization observed in these cells when they are discharged at high rates. The electrolyte layer was also found to develop with a density less than one‐half of the theoretical value.