The effect of Ni content on the phase structures and electrochemical properties of V2.1TiNix (x=0.1–0.9) hydrogen storage alloys

The phase structures and electrochemical properties of V2.1TiNix (x=0.1,0.3,0.5,0.7,0.9) alloys were investigated by the general electrochemical techniques and X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray spectrometer and emission spectrochemical analysis. Nickel added into V2.1Ti alloy plays a key role in the performance of the new alloys, due to the formation of a continuous TiNi-based secondary phase in the form of a three-dimensional network around the main phase. Though the hydrogen absorbed by the alloy reduces with the increase of nickel content, the actual electrochemical discharge capacity and the high-rate discharge capability are improved noticeably. Among the studied alloys, V2.1TiNi0.5 with a good combination of the main phase and the secondary phase has the best overall electrochemical performance.