Performance of AA-size spiral-wound lithium secondary cells

Hermetic AA-size lithium secondary cells with spiral-wound electrode design were used to compare the performance of TiS₂ and Li_xCoO₂ based cathodes. The TiS₂ based cells, with a system-optimized electrolyte, demonstrated significantly greater cycle life although their load voltage plateau was approximately 1.8 V lower than that of the Li_xCoO₂ based cells. In an attempt to extend the cycle life of an Li/Li_x CoO₂ cell, KPG, a solvent used routinely in organic synthesis to solubilize and stabilize alkaline-earth metals, was added to the methyl formate (MeF)-based electrolyte at a concentration of 1 v/o. As shown by the data presented, the effect of this addition was a doubling in cycle life combined with a doubling in cycle capacity. Although these improvements are significant in improving the performance of the Li/Li_xCoO₂ cell, this cell still has significantly lower cycle life than an Li/TiS₂ cell