Lithium Anode Limited Cycle Battery Investigation

The purpose of this experimental program is to develop technology sufficient to construct batteries based on the lithium-cupric fluoride couple. During this period, separator material with a resistance of less than 1 ohmsq in. has been evaluated and sheet lithium electrodes have been discharged anodically for 100 hr at 10 mAsq. in. with less than 100 mV polarization. Aluminum cased cells have been constructed that have delivered 32.2 A-hr to a 2. 0-V endpoint and had an energy to weight ratio of 72.5 W-hrlb of total cell weight. In these aluminum cased cells which are better sealed than the plastic cells used in preliminary tests, low water content in the cell becomes very important. Water introduced in the electrolyte, cathode preparation or separator reacts with the lithium to form hydrogen. Pressure from the gas evolution distorts the metal case and the resulting movement and misalignment can result in shorting the active elements of the cell. Water in the cupric fluoride used in cathodes in cells does result in higher voltage discharges, possibly because the resulting soluble copper species gives a lower effective current density.