Metal hydride alloy with catalyst particles and channels
The performance of an AB x type metal hydride alloy is improved by adding an element to the alloy which element is operative to enhance the surface area morphology of the alloy. The alloy may include surface regions of differing morphologies.
1. A hydrogen storage material for use as anode in an electrochemical cell which also contains a cathode and an electrolyte, said hydrogen storage material having an interface oxide region which in the use of said hydrogen storage material in said electrochemical cell constitutes the interface between said electrolyte and the bulk of said hydrogen storage material, said interface oxide region having channels distributed therein, said channels having interior surfaces; said interface oxide region characterized by the presence of metallic, catalytic particles formed on said channel surfaces: wherein at least some of the metallic, catalytic particles on said channel surfaces are directly exposed to said electrolyte interiorly of said channels.
2. The hydrogen storage material of claim 1 , wherein the channels have a cross-sectional dimension of 25-150 angstroms and a length dimension greater than the cross-sectional dimension.
3. The hydrogen storage material of claim 1 , wherein the average dimension of the metallic, catalytic particles is 5-15 angstroms.
4. The hydrogen storage material of claim 1 , wherein the metallic catalytic particles include Ni.
5. The hydrogen storage material of claim 1 , wherein said material is selected from the group consisting essentially of AB 2 , AB 3 , AB 5 , or A 2 B 7 .
6. A hydrogen storage material for use as anode in an electrochemical cell which also contains a cathode and an electrolyte, said hydrogen storage material having a bulk metal region and an interface oxide region, which in the use of said hydrogen storage material in said electrochemical cell constitutes the interface between said electrolyte and the bulk of said hydrogen storage material, said interface region having a plurality of catalytic channels defined therethrough, said channels having a cross-sectional dimension in the range of 25-150 angstroms and a length which is greater than said cross-sectional dimension, said channels including a plurality of catalytic sites formed on and extending from the interior surfaces thereof.
7. The material of claim 6 , wherein said catalytic sites have a concentration of nickel which is greater than the concentration of nickel in the remainder of said alloy.
8. An AB x (1≦x≦5) metal hydride material for use as anode in an electrochemical cell which also contains a cathode and an electrolyte, said hydrogen storage material having a bulk region and an interface oxide region, which in the use of said hydrogen storage material in said electrochemical cell constitutes the interface between said electrolyte and the bulk of said hydrogen storage material, said interface oxide region having a plurality of catalytic channels disposed therethrough, said channels having an average cross-sectional dimension in the range of 25-150 angstroms and a length which is greater than said cross-sectional dimension, said channels having catalytic particles formed on and extending from the interior surfaces thereof.
9. The metal hydride material of claim 8 , wherein said interface oxide region forms a matrix portion with at least one catalytic channels portion disposed in spaced relationship therein, said at least one channels portion having a concentration of said catalytic channels defined therein.
10. The metal hydride material of claim 9 , wherein a composition of the matrix portion of said metal hydride material differs from the concentration of said at least one channel portions thereof.
11. The hydrogen storage material of claim 1 , having a charge transfer resistance of no more than 50 Ohm/g at −40° C. as measured by AC impedance.
12. The hydrogen storage material of claim 1 , wherein said material includes an additive selected from the group consisting of: Si, Mo, Y, Sn, Sb, and combinations thereof.