Investigation and Development of Lithium-Carbon Monofluoride AA-Size Cells

摘要

The technical goals for Phase I consisted of a best effort baseline cell designusing off the shelf materials, processing and assembly techniques. The goals of this Phase were met with additional improvements that can be made to improve the performance of the cell design to meet the longer term program goals. In summary, the following conclusions apply to the cell development efforts of the program: Baseline cell design is complete. 100 cells have been built for the current design and were evaluated on a comprehensive test program. The design as presently implemented utilizes a spiral wound construction with a case negative design. Assessment of Phase I performance is complete. Current performance yields typically 2.2 Ahr out of the cell versus a final goal of 1.8 Ahr or greater. Best performance to date is 2.3 Ahr. Low temperature (28 deg F) and higher rate performance has been very good and exceeds expectations. Problems were resolved with a shortfall in cell capacity as a result of degradation of cathode integrity during discharge due to loss of adhesion to the cathode substrate. A majority of the development effort of Phase I was in the area of improving cathode adhesion and fabricating handleable electrodes. Originally the cathodes had enough integrity to be assembled into cells, but the adhesion was lost after the cells are assembled due to swelling when in contact with the electrolyte and also due to discharge. These problems have been resolved. Initial samples of Dr. Yazami produced CFx were evaluated and found to be unacceptable due to heavy corrosion of internal components. Corrosion is indicative of HF inside the cell. CFx was washed as per Yazami to eliminate metal fluoride compounds which could be producing HF and was also unsuccessful to date. Other CFx material received in January 1996 from Yazami also proved to unacceptable once coin cells were ma.