Hydrogen storage materials having excellent kinetics, capacity, and cycle stability
A BCC phase hydrogen storage alloy capable of storing approximately 4.0 wt. % hydrogen and delivering reversibly up to 3.0 wt. % hydrogen at temperatures up to 110° C. The hydrogen storage alloys also possess excellent kinetics whereby up to 80% of the hydrogen storage capacity of the hydrogen storage alloy may be reached in 30 seconds and 80% of the total hydrogen storage capacity may be desorbed from the hydrogen storage alloy in 90 seconds. The hydrogen storage alloys also have excellent stability which provides for long cycle life.
1. A BCC hydrogen storage alloy processed to be substantially free of oxides, said alloy stably absorbing at least 80% of its hydrogen storage capacity within 90 seconds, desorbing at least 80% of its total hydrogen storage capacity within 30 seconds, and reversibly storing at least 2.2 weight percent hydrogen at 90° C., said alloy reversibly storing at least 1.5 weight percent hydrogen per cycle for at least 700 cycles.
2. The hydrogen storage alloy according to claim 1 , wherein at least 85% of said hydrogen storage alloy reverts to a BCC crystal structure from a FCC crystal structure upon desorption of hydrogen from said hydrogen storage alloy.
3. The hydrogen storage alloy according to claim 1 , wherein at least 90% of said hydrogen storage alloy reverts to a BCC crystal structure from a FCC crystal structure upon desorption of hydrogen from said hydrogen storage alloy.
4. The hydrogen storage alloy according to claim 1 , wherein at least 95% of said hydrogen storage alloy reverts to a BCC crystal structure from a FCC crystal structure upon desorption of hydrogen from said hydrogen storage alloy.
5. The hydrogen storage alloy according to claim 1 , wherein the lattice constant of said hydrogen storage alloy is in the range of 3.015 to 3.045 angstroms.
6. The hydrogen storage alloy according to claim 5 , wherein the lattice constant of said hydrogen storage alloy is in the range of 3.015 to 3.028 angstroms.
7. The hydrogen storage alloy according to claim 5 , wherein the lattice constant of said hydrogen storage alloy is in the range of 3.028 to 3.045 angstroms.
8. The hydrogen storage alloy according to claim 1 , wherein the surface of said hydrogen storage alloy is substantially free of any oxides via low oxygen processing to inhibit and/or remove oxides at each step.
9. The hydrogen storage alloy according to claim 1 , wherein said hydrogen storage alloy reversibly stores up to 2.83 weight percent hydrogen at 90° C.
10. The hydrogen storage alloy according to claim 1 , wherein said alloy is cooled at a quench rate in the range of 10 2 to 10 3 ° C./second.
11. The hydrogen storage alloy according to claim 1 , wherein said hydrogen storage alloy has a single phase BCC structure.
12. The hydrogen storage alloy according to claim 1 , wherein said hydrogen storage alloy comprises:
8.0 to 45 atomic percent titanium;
5.0 to 75 atomic percent vanadium; and
10 to 65 atomic percent chromium.
13. The hydrogen storage alloy according to claim 1 , wherein said hydrogen storage alloy further comprises one or more modifier elements selected from nickel, manganese, molybdenum, aluminum, iron, silicon, magnesium, ruthenium, or cobalt, wherein said modifier elements are present in an amount greater than 0 up to 16 atomic percent.
14. The hydrogen storage alloy according to claim 8 , wherein oxides are removed from said hydrogen storage alloy at each processing step.
15. The hydrogen storage alloy according to claim 8 , wherein the formation of oxides on said hydrogen storage alloy are inhibited at each step.
16. The hydrogen storage alloy according to claim 1 , wherein said hydrogen storage alloy comprises:
10 to 65 atomic percent chromium.
17. A BCC hydrogen storage alloy processed to be substantially free of oxides, said alloy reversibly storing at least 1.5 weight percent hydrogen for at least 700 cycles.