Nano Energy | 2019
Expanded lithiation of titanium disulfide: Reaction kinetics of multi-step conversion reaction
Abstract
Abstract Phase evolution during a thorough Li\xa0+\xa0ion s insertion of electrode materials governs their battery performance during charge and discharge. Here we investigated the lithiation pathway of titanium disulfide using in situ TEM combined with synchrotron-based pair distribution function measurement and first-principles calculations. A 2D intercalation reaction proceeds along with a transition from van der Waals interaction between Ti–S slabs to the covalent bonding of S–Li–S, with no symmetry broken. Further lithiation triggers unconventionally multiple step conversion reactions as proved: LiTiS 2 →TiS→Ti 2 S→Ti. The conversion reaction pathway is also verified in fully discharged sample in coin-cell. The expanded conversion chemistry is supposed to increase the capacity of TiS 2 electrode and downgrade the cyclability, whereas the existence of intermediate phases shows the promise of improving the reversibility with a successful control of the state of charge.