Structure and electrochemical hydrogen storage properties of A2B-type Ti–Zr–Ni alloys

Elemental substitution of part Ti by Zr has been carried out for Ti2Ni alloy to form Ti2−xZrxNi (x = 0, 0.2, 0.4) alloys. Mechanical milling and subsequent heat treatment have been used to prepare non-equilibrium Ti–Zr–Ni alloys. The effects of Zr addition on the structure and discharge properties of Ti2Ni alloy were investigated. The addition of Zr could enhance the discharge capacity of the non-equilibrium Ti2Ni alloy at electrolyte temperatures of 313 and 333 K. For instance, the non-equlibrium Ti1.6Zr0.4Ni alloy had a stable discharge capacity of about 210 mAh/g at 313 K. However, the protective surface layer formed during heat treatment was destroyed at a high electrolyte temperature of 333 K, and thus a severe capacity loss during cycling.

► Successful synthesis of non-equilibrium A2B-type Ti–Zr–Ni alloys.
► Zr could effectively enhance the stable discharge capacity of the non-equilibrium alloy.
► We present the electrochemical hydrogen absorption/desorption mechanism of the alloys.
► The capacity loss could be attributed to the damage of surface layer and subsequent corrosion.