Applications of Ti–Ni alloys for secondary batteries

A flexible wire Li battery was fabricated using a thermal-sulfurized Ti–Ni alloy as a cathode material. Sulfides formed by the sulfidation had a layered structure consisting of NiS1.97, NiS and Ti8.2S11. Sulfur pressure was an important factor to control the sulfur content in the sulfide and the thickness of the sulfurized layers. No apparent changes in thermal and mechanical properties were found after the sulfidation of the Ti–Ni alloy at 80 kPa. The shape memory effect and the superelasticity still remained after the sulfidation. The discharge capacity of sulfurized Ti–Ni alloy applied to the Li battery was measured to be over 400 mAh/g-NiS1.97 until the fifth cycle. The initial discharge capacity of our homemade wire battery with 1 mm of diameter and 100 mm of length was 0.66 mAh-cell.