Titanium Sulfides as Intercalation-Type Cathode Materials for Rechargeable Aluminum Batteries.

We report the electrochemical intercalation-extraction of aluminum (Al) in the layered TiS ₂ and spinel-based cubic Cu _0.31 Ti ₂ S ₄ as the potential cathode materials for rechargeable Al-ion batteries. The electrochemical characterizations demonstrate the feasibility of reversible Al intercalation in both titanium sulfides with layered TiS ₂ showing better properties. The crystallographic study sheds light on the possible Al intercalation sites in the titanium sulfides, while the results from galvanostatic intermittent titration indicate that the low Al ³⁺ diffusion coefficients in the sulfide crystal structures are the primary obstacle to facile Al intercalation-extraction.