Structural, hydrogen storage, and electrochemical properties of Laves phase-related body-centered-cubic solid solution metal hydride alloys

Abstract

Structure, gaseous phase hydrogen storage, and electrochemical properties of a series of Laves phase-related BCC solid solution metal hydride alloys with BCC/C14 ratios ranging from 0.09 to 8.52 were studied. Some properties are correlated to the phase abundance and V-content in the alloy with monotonic evolutions, for example, lattice constant, phase abundance, and hydrogen storage pressure. Other properties such as gaseous phase capacities, PCT hysteresis, high-rate dischargeability, and bulk hydrogen diffusion correlate better with the C14 phase crystallite size, which are considered to be more related to the synergetic effect between main and secondary phases. In contrast with conventional metal hydride alloys used in NiMH batteries, the electrochemical discharge capacities of these alloys are not between the maximum and the reversible hydrogen storage measured in the gaseous phase. The current study's alloys have electrochemical capacities that are insensitive to composition but have much room for improvement, with high-rate dischargeabilities that are superior compared to other commercially available alloys. With further research, these alloys show potential for high-rate battery applications.