Analysis of cycled 1 Ah Li-TiS2 cells

The use of rechargeable lithium batteries is presently restricted because of their limited cycle life and safety issues. To understand the causes responsible for these limitations, 1 Ah Li-TiS₂ cells were tested and studied by nondestructive and destructive methods before and after cycling. The nondestructive methods included microcalorimetry and AC impedance spectroscopy. Cycled cells showed higher heat output after cycling. Cells were disassembled and the components were analyzed for their physical and chemical properties. The following changes were observed in the cell components with cycling: electrolyte consumption, lithium electrode swelling and disintegration, and separator dry out. No significant disintegration or swelling of the cathode was observed with cycling. Lithium dendrites were seen on the anode and cathode separators of the cells that failed due to shorts. The results of these studies indicated that capacity loss observed on cycling is mainly due to electrolyte degradation/consumption