Electrochemical hydrogen storage properties of a non-equilibrium Ti ₂Ni alloy

A crystalline Ti ₂Ni alloy was mechanically milled and subsequently annealed to form a non-equilibrium Ti ₂Ni alloy. This non-equilibrium structure could restrain the formation of irreversible metal hydride during charging. Consequently, we demonstrated that the alloy had a discharge capacity of 336 mAh g ^-1, which was much higher than those of other Ti ₂Ni alloys reported in the literature and also higher than that of the commercial LaNi ₅-based alloy. An electrochemical hydrogen absorption-desorption mechanism of the alloy during cycling is also presented.