Optimization of Zr-based hydrogen storage alloys for nickel-hydride batteries

The hydrogen storage and electrochemical properties of Zr(Ni0.6Mn0.3V0.1Cr0.05)2 alloy were optimized by multi-component substitution and changing the stoichiometry. Firstly, the effects of the partial substitution of Ti for Zr were studied. Ti substitution for Zr is effective in improving the activation behavior but results in higher hydrogen equilibrium pressure. Then, to decrease the hydrogen equilibrium pressure, the effects of substitution of V for Mn atoms were investigated. P-C isotherms indicated that substitution of V for Mn led to a decrease of the hydrogen equilibrium pressure and an increase of maximum hydrogen storage capacity. Finally, a series of Zr0.8Ti0.2(Ni0.6Mn0.2V0.2Cr0.05)x alloys were studied to reveal the effects of the stoichiometry. With increasing value of x, the activation property, the discharge capacity and the high rate dischargeability are improved. Among all the alloys, Zr0.8Ti0.2(Ni0.6Mn0.2V0.2Cr0.05)2.2 alloy shows the best comprehensive electrochemical performance and is promising for practical application in nickel-hydride batteries.