In Part 2 of this report, the hydrogen gas charging and electrochemical properties of a series of AB 2-based metal alloys (Ti 12.5Zr 21V 10Cr 8.5Mn xCo 1.5Ni 46.5-x) designed to have different fractions of Zr-Ni-type secondary phases by varying the Mn/Ni-content were studied to establish correlations of these properties with abundances of the secondary phases. In the gas charging, the general trend of pressure- concentration-temperature slope factor and hysteresis is to diminish with increase in the Zr 7Ni 10 phase abundance; the trend of reversible hydrogen storage capacity is to increase as the TiNi-derived AB phase abundance increases. As for the electrochemical properties, the number of activation cycles needed to achieve a given percentage of capacity and power decreases with increase in the total amount of secondary phases. Trends of changes in both the total and reversible capacities follow that in AB phase abundance; the evolution of high-rate dischargeability, bulk diffusion, and surface exchange current is similar to that of Zr 7Ni 10 phase abundance - increase in the beginning and decrease afterward as the Mn-content in the alloy increases. Other properties, such as metal-hydrogen bond strength and maximum gaseous phase storage capacity, are predominately dependent on the alloys' composition, i.e. the Mn/Ni ratio.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering