INVESTIGATION ON THE STRUCTURE AND ELEC TROCHEMICAL PROPERTIES OF SUPER-STOICH IOMETRIC Ti-Zr-V-Mn-Cr-Ni HYDROGEN STORAGE ELECTRODE ALLOYS
超化学计量比Ti-Zr-V-Mn-Cr-Ni贮氢电极合金相结构及电化学性能研究

The structure and electrochemical properties of the super-stoichiometric Ti-based hydrogen storage alloys (Ti0.8Zr0.2)(V0.533Mn0.107Cr0.16Ni0.2)x (x=2, 3, 4, 5, 6) have been studied. It is found by XRD and EDS analysis that these alloys all mainly consist of two phases: a C14 type Laves phase with hexagonal structure and a V-based solid solution phase with bcc structure. The lattice parameters and unit cell volumes of the two phases all decrease with increasing x. The electrochemical studies show that the maximum discharge capacity, the discharge potential, the high rate dischargeability (HRD), the cyclic stability, the exchange current density Io and the limiting current density IL of the alloys all increase with increasing x from 2 to 5. When x reaches 6, the discharge potential, HRD and cyclic stability are still increasing proportionately, while the maximum discharge capacity, I0 and IL all decrease. Furthermore, the alloy electrodes become more difficult to be activated for the higher stoichiometric alloys.