Effect of Zr additions on the electrode characteristics of nanocrystalline TiNi-type hydrogen storage alloys

The effect of Zr on the structure and electrochemical properties of nanocrystalline TiNi-type alloys was studied. These materials were prepared by mechanical alloying (MA) followed by annealing. It was found that the respective replacement of Ni in nanocrystalline TiNi by Zr, and by Zr and Fe improved not only the discharge capacity but also the cycle life of these electrodes. In the nanocrystalline TiNi0.875Zr0.125, a powder discharge capacity up to 135 mA h g−1 was measured on the 10th cycle (at 40 mA g−1 discharge current). The studies show that the electrochemical properties of Ni-MH batteries are a function of the microstructure and the chemical composition of the used electrode materials.