Mechanism of early capacity loss of Ti2Ni hydrogen-storage alloy electrode

The mechanism underlying the rapid, early, capacity loss of titanium-based (Ti2Ni) hydrogen-storage alloys is examined via X-ray diffraction analysis. The formation and accumulation of Ti2NiH0.5, a hydride phase that cannot be reversibly charged/discharged according to the experimental results, is proposed as a dominant cause of the early capacity loss of such electrodes.