The high rate capability of two electrochemically distInct rechargeable lithium power sources will be examined in order to quantitatively determine those factors which promote long cycle life and low polarization in high discharge rate applications. Both systems employ a sulfur dioxide electrolyte which demonstrates high ionic conductivity; however, in one system the electrochemical discharge results in a dilution of the electrolyte while in the other system the net electrolyte concentration is invariant over the discharge duration. Based upon the high rate performance comparison one system will be selected for further optimization over the 0-25 deg temperature range. A new commercially available microporous tefzel separator will be evaluated for this high rate application. - this material is inert to both lithium and the oxidizing electrolyte \ -and is available as 1.5 mil thick sheets between porosities of 40, 60, and 80%. Possible trade-offs between high rate capacity and cycle life will be investigated. The final stage of phase I program will evaluate the effects of electrolyte changes on the high rate performance of the chosen system.
