V-Ti alloy is very attractive for anode material of Ni/MH secondary battery because of its large hydrogen storage capacity. However, for being incapable of discharging in KOH electrolyte the alloy has not been used for anode material.
V-Ti alloy was sintered with Ni powder to have a catalytic effect of hydrogen absorption/desorption in KOH electrolyte. The sintering condition was 900℃, 5min and in this condition, the amount of Ni powder was varied to investigate the electrode characteristics and surface modification.
All electrodes prepared under this condition were fully activated within 10 cycles. The discahrge capacity of the electrodes was increased up to the peak value and then decreased. In case of $V_0.9Ti_0.1$ alloy the optimal amount of Ni powder showing highest discharge capacity, 302 mAh/g, was 25wt%. As the amount of Ni powder was increased the activation behaviour and rate capability were improved and the discharging overpotential was decreased.
The second phase formed during sintering was $VNi_3$. The $VNi_3$ can't absorb hydrogen, which decreased the theoretical capacity of the electrode, but it has a high catalytic effect of hydrogen absorption/desorption in KOH electrolyte, which improved the rate capability and the discharge efficiency of the electrode.
If thinner $VNi_3$ is evenly distributed around V-Ti alloy the discharge capacity of the electrode will be increased.
For developing anode materials of Ni/MH secondary battery. It may be suggested for new process to use the metal hydride, by surface modification of it, which has large hydrogen storage capacity, but can't be discharged in KOH electrolyte.
