Capacity decline of ambient temperature secondary Li-TiS₂ cells

The main objective of the study described was to identify the causes responsible for the capacity losses observed during cycling of secondary Li-TiS₂ cells. Experimental Li-TiS₂ cells were fabricated and tested for their cycle life performance. The open circuit voltage of the cells was monitored during the rest period between the charging and discharging. The polarization at the Li and TiS₂ electrodes was also monitored during cycling. Cycled cells were disassembled and the cathodes were analyzed by various analytical techniques. The results of the study indicate that the observed capacity loss is almost entirely due to the increased polarization of the TiS₂ electrode with cycling. The electrolyte was found to degrade during cycling and the degradation products were found to deposit at the TiS₂ electrode, which probably lead to the higher polarization.