U.S. patent application number 12/939125 was filed with the patent office on 2012-03-22 for hydrogen-storage alloy.
This patent application is currently assigned to National Tsing Hua University. Invention is credited to SWE-KAI CHEN.
Application Number | 20120070333 12/939125 |
Document ID | / |
Family ID | 45817929 |
Filed Date | 2012-03-22 |
United States Patent
Application |
20120070333 |
Kind Code |
A1 |
CHEN; SWE-KAI |
March 22, 2012 |
HYDROGEN-STORAGE ALLOY
Abstract
In a hydrogen-storage alloy which is a high-entropy alloy having
a molecular formula of
Co.sub.uFe.sub.vMn.sub.wTi.sub.xV.sub.yZr.sub.z, the
hydrogen-storage alloy is an alloy free from rare-earth elements
and having a stable single C14 Laves phase structure. The
hydrogen-storage alloy has a high capacity of absorbing and
releasing hydrogen under ambient temperature and pressure and a
high hydrogen-storage capacity at room temperature, so that the
hydrogen-storage alloy can be used extensively in the fields of
hydrogen storage, heat storage, heat pump, hydrogen purification,
isotope separation, secondary battery and fuel cell without
producing harmful polluted gases, and the hydrogen-storage alloy
has high potential for the development of a green energy
source.
Inventors: |
CHEN; SWE-KAI; (Hsinchu
City, TW) |
Assignee: |
National Tsing Hua
University
Hsinchu City
TW
|
Family ID: |
45817929 |
Appl. No.: |
12/939125 |
Filed: |
November 3, 2010 |
Current U.S.
Class: |
420/581 |
Current CPC
Class: |
C01B 3/0031 20130101;
C01B 2203/066 20130101; Y02E 60/327 20130101; Y02P 20/129 20151101;
C22C 30/00 20130101; Y02E 60/32 20130101; C01B 3/508 20130101 |
Class at
Publication: |
420/581 |
International
Class: |
C22C 30/00 20060101
C22C030/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 16, 2010 |
TW |
099131383 |
Claims
1. A hydrogen-storage alloy, having a molecular formula of
Co.sub.uFe.sub.vMn.sub.wTi.sub.xV.sub.yZr.sub.z, wherein
0.5.ltoreq.u.ltoreq.2.0, 0.5.ltoreq.v.ltoreq.2.5,
0.5.ltoreq.w.ltoreq.2.0, 0.5.ltoreq.x.ltoreq.2.5,
0.4.ltoreq.y.ltoreq.3.0 and 0.4.ltoreq.z.ltoreq.3.0, and atomic
percentages used for representing contents of the hydrogen-storage
alloy indicating that the content of Co falls within the range from
9.0 to 28.6, and the remaining contents fall within the range from
14.3 to 18.2; or the content of Fe falls within the range from 9.0
to 33.3 and the remaining contents fall within the range from 13.3
to 18.2; or the content of Mn falls within the range from 9.0 to
28.6, and the remaining contents fall within the range from 14.3 to
18.2; or the content of Ti falls within the range from 9.0 to 33.3,
and the remaining contents fall within the range from 13.3 to 18.2;
or the content of V falls within the range from 9.0 to 33.3 and the
remaining contents fall within the range from 13.3 to 18.2; or the
content of Zr falls within the range from 7.5 to 37.5, and the
remaining contents fall within the range from 12.5 to 18.5.
2. The hydrogen-storage alloy of claim 1, wherein the hydrogen
storage alloy is in a C14-Laves phase.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the invention
[0002] The present invention relates to a hydrogen-storage alloy
system that contains no rare-earth elements, and, more
particularly, to a hydrogen-storage alloy system with a stable
alloy structure and a high capacity of absorbing and releasing
hydrogen under ambient temperature and pressure.
[0003] 2. Description of Related Art
[0004] Owing to energy crisis and harms done to the earth by the
present ways of using energy sources, the development of green
energy sources, including the usage of natural hydrogen energy,
solar energy, bio-energy, geothermal energy, and tidal energy, in
the most economic condition becomes a notable research and
development subject, and any energy source and method causing no
threats to the environmental pollution is studied extensively.
[0005] Hydrogen is a chemical element whose reserve ranks the third
among all elements in the world. Heat can be produced in a quantity
of 140 kJ per kg of hydrogen when hydrogen gas is combusted. In
addition to the advantage of an excellent combustion rate, the
product produced by the combustion is pollution-free water, and
thus hydrogen has become a popular green energy source. Since Ni--H
battery features a large storage capacity and a high stability, the
Ni--H battery becomes very popular when it comes to the decision of
choosing an energy source for applications in different areas,
particularly in the research and development of hydrogen fuel cell
cars. However, hydrogen is highly flammable, so that if hydrogen is
used as energy for generating electric power, the storage of
hydrogen becomes a safety issue. On the other hand, hydride
features a low price, a high safety, an advantage of not producing
green house gases, a high storage capacity, and a property of
absorbing and releasing hydrogen easily, and thus hydride is
considered as an excellent hydrogen storage material.
[0006] In recent years, high-entropy alloy (HEA) is one of the most
noticeable materials and composed of at least five principal
elements, and each element has an atomic percentage falling within
a range of 5%.about.35%. After the elements are mixed uniformly in
a liquid phase at a high temperature and then cooled, a hydrogen
storage alloy with the characteristics of high entropy and low
Gibbs free energy is formed. Compared with a conventional alloy,
the high-entropy alloy has a simpler microstructure that can be
used to produce a nano-scaled material easily and features the
advantages of high thermal stability, excellent ductility and
compressibility, high hardness, and outstanding electric and
magnetic properties. It is noteworthy to point out that the
proportion of metal elements selected and mixed to form such an
alloy material has a substantial effect of storing hydrogen, and
absorbing/desorbing hydrogen of the alloy, and optimal conditions
are applied for the usage of the alloy.
SUMMARY OF THE INVENTION
[0007] Therefore, it is a primary objective of the present
invention to provide a hydrogen-storage alloy with an optimal
hydrogen-storage performance to enhance the usage. The inventor of
the present invention developed a hydrogen-storage alloy that uses
a vacuum arc remelting (VAR) method and a thermal treatment, if
necessary, to prepare an as-cast high-entropy alloy.
[0008] The hydrogen-storage alloys of the present invention have a
molecular formula Co.sub.uFe.sub.vMn.sub.wTi.sub.xV.sub.yZr.sub.z,
where 0.5.ltoreq.u.ltoreq.2.0, 0.5.ltoreq.v.ltoreq.2.5,
0.5.ltoreq.w.ltoreq.2.0, 0.5.ltoreq.x.ltoreq.2.5,
0.4.ltoreq.y.ltoreq.3.0 and 0.4.ltoreq.z.ltoreq.3.0, and such
hydrogen-storage alloys can be a non-equal molar alloy material
with a structure of a single C14 Laves phase, and the structure is
stable and capable of absorbing and desorbing hydrogen in an
operation environment under ambient temperature and pressure and a
high ratio of the weight percentage of the total number of hydrogen
atoms to the weight percentage of the total number of alloy atoms
(H/M value), which indicates a high hydrogen-storage capacity.
[0009] The hydrogen-storage alloys of the present invention can be
used extensively in the areas of hydrogen storage, heat storage,
heat pump, hydrogen purification, isotope separation, secondary
battery and fuel cell.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention, as well as its many advantages, may be
further understood by the following detailed description and
drawings in which:
[0011] FIG. 1 is a schematic view showing the distribution of all
compositions of a hydrogen-storage alloy in accordance with the
present invention;
[0012] FIG. 2A shows X-ray diffraction patterns of hydrogen-storage
alloys with different titanium contents of the present invention
before the test of a pressure-composition-isotherm curve takes
place;
[0013] FIG. 2B shows X-ray diffraction patterns of hydrogen-storage
alloys with different titanium contents of the present invention
after the test of a pressure-composition-isotherm curve takes
place;
[0014] FIG. 3 is a temperature versus titanium content graph of a
hydrogen-storage alloy of the present invention showing the
hydrogen absorption capacity of the hydrogen storage alloys with
different titanium contents at different temperatures;
[0015] FIG. 4A is a pressure-composition-isotherm curve of
hydrogen-storage alloys with different titanium contents at
25.degree. C. in accordance with the present invention;
[0016] FIG. 4B is a pressure-composition-isotherm curve of
hydrogen-storage alloys with different titanium contents at
80.degree. C. in accordance with the present invention;
[0017] FIG. 5A shows X-ray diffraction patterns of hydrogen-storage
alloys with different vanadium contents of the present invention
before the test of a pressure-composition-isotherm curve takes
place;
[0018] FIG. 5B shows X-ray diffraction patterns of hydrogen-storage
alloys with different vanadium contents of the present invention
after the test of a pressure-composition-isotherm curve takes
place;
[0019] FIG. 6 is a temperature versus vanadium content graph of a
hydrogen-storage alloy of the present invention showing the
hydrogen absorption capability of the hydrogen storage alloy with
different vanadium contents at different temperatures;
[0020] FIG. 7A shows X-ray diffraction patterns of hydrogen-storage
alloys with different vanadium contents of the present invention
before the test of a pressure-composition-isotherm curve takes
place;
[0021] FIG. 7B shows X-ray diffraction patterns of hydrogen-storage
alloys with different vanadium contents of the present invention
after the test of a pressure-composition-isotherm curve takes
place;
[0022] FIG. 8 is a temperature versus vanadium content graph of a
hydrogen-storage alloy of the present invention showing the
hydrogen absorption capacity of the hydrogen storage alloy with
different vanadium contents at different temperatures;
[0023] FIG. 9A shows X-ray diffraction patterns of hydrogen-storage
alloys with different manganese contents of the present invention
before the test of a pressure-composition-isotherm curve takes
place;
[0024] FIG. 9B shows X-ray diffraction patterns of hydrogen-storage
alloys with different manganese contents of the present invention
after the test of a pressure-composition-isotherm curve takes
place;
[0025] FIG. 10 is a temperature versus manganese content graph of a
hydrogen-storage alloy of the present invention showing the
hydrogen absorption capacity of the hydrogen storage alloy with
different manganese contents at different temperatures;
[0026] FIG. 11A shows X-ray diffraction patterns of
hydrogen-storage alloys with different cobalt contents of the
present invention before the test of a
pressure-composition-isotherm curve takes place;
[0027] FIG. 11B shows X-ray diffraction patterns of
hydrogen-storage alloys with different cobalt contents of the
present invention after the test of a pressure-composition-isotherm
curve takes place;
[0028] FIG. 12 is a temperature versus cobalt content graph of a
hydrogen-storage alloy of the present invention showing the
hydrogen absorption capacity of the hydrogen storage alloy with
different cobalt contents at different temperatures;
[0029] FIG. 13A shows X-ray diffraction patterns of
hydrogen-storage alloys with different iron contents of the present
invention before the test of a pressure-composition-isotherm curve
takes place;
[0030] FIG. 13B shows X-ray diffraction patterns of
hydrogen-storage alloys with different iron contents of the present
invention after the test of a pressure-composition-isotherm curve
takes place;
[0031] FIG. 14 is a temperature versus iron content graph of a
hydrogen-storage alloy of the present invention showing the
hydrogen absorption capacity of the hydrogen storage alloy with
different cobalt contents at different temperatures.
[0032] Description of Designations Used for Representing Respective
Elements of the Present Invention: According to the design of
experiment of the present invention, any alloy with a mole ratio of
1.0 is identical to each other. In other words, A2=B3=C3=D4=E4=F2.
An alloy with an equal mole ratio correlates to an indicated alloy
of the non-equal molar alloys having different metal contents in
the system.
[0033] A1 is a high-entropy hydrogen-storage alloy containing
titanium of 0.5 mole ratio.
[0034] A2 is a high-entropy hydrogen-storage alloy containing
titanium of 1.0 mole ratio.
[0035] A3 is a high-entropy hydrogen-storage alloy containing
titanium of 1.5 mole ratio.
[0036] A4 is a high-entropy hydrogen-storage alloy containing
titanium of 2.0 mole ratio.
[0037] A5 is a high-entropy hydrogen-storage alloy containing
titanium of 2.5 mole ratio.
[0038] B1 is a high-entropy hydrogen-storage alloy containing
zircon of 0.4 mole ratio.
[0039] B2 is a high-entropy hydrogen-storage alloy containing
zircon of 0.7 mole ratio.
[0040] B3 is a high-entropy hydrogen-storage alloy containing
zircon of 1.0 mole ratio.
[0041] B4 is a high-entropy hydrogen-storage alloy containing
zircon of 1.3 mole ratio.
[0042] B5 is a high-entropy hydrogen-storage alloy containing
zircon of 1.7 mole ratio.
[0043] B6 is a high-entropy hydrogen-storage alloy containing
zircon of 2.0 mole ratio.
[0044] B7 is a high-entropy hydrogen-storage alloy containing
zircon of 2.3 mole ratio.
[0045] B8 is a high-entropy hydrogen-storage alloy containing
zircon of 2.6 mole ratio.
[0046] B9 is a high-entropy hydrogen-storage alloy containing
zircon of 3.0 mole ratio.
[0047] C1 is a high-entropy hydrogen-storage alloy containing
vanadium of 0.4 mole ratio.
[0048] C2 is a high-entropy hydrogen-storage alloy containing
vanadium of 0.7 mole ratio.
[0049] C3 is a high-entropy hydrogen-storage alloy containing
vanadium of 1.0 mole ratio.
[0050] C4 is a high-entropy hydrogen-storage alloy containing
vanadium of 1.3 mole ratio.
[0051] C5 is a high-entropy hydrogen-storage alloy containing
vanadium of 1.7 mole ratio.
[0052] C6 is a high-entropy hydrogen-storage alloy containing
vanadium of 2.0 mole ratio.
[0053] C7 is a high-entropy hydrogen-storage alloy containing
vanadium of 2.3 mole ratio.
[0054] C8 is a high-entropy hydrogen-storage alloy containing
vanadium of 2.6 mole ratio.
[0055] C9 is a high-entropy hydrogen-storage alloy containing
vanadium of 3.0 mole ratio.
[0056] D1 is a high-entropy hydrogen-storage alloy containing
manganese of 0 mole ratio.
[0057] D2 is a high-entropy hydrogen-storage alloy with manganese
of 0.5 mole ratio.
[0058] D3 is a high-entropy hydrogen-storage alloy with manganese
of 0.75 mole ratio.
[0059] D4 is a high-entropy hydrogen-storage alloy with manganese
of 1.0 mole ratio.
[0060] D5 is a high-entropy hydrogen-storage alloy with manganese
of 1.25 mole ratio.
[0061] D6 is a high-entropy hydrogen-storage alloy with manganese
of 1.5 mole ratio.
[0062] D7 is a high-entropy hydrogen-storage alloy with manganese
of 2.0 mole ratio.
[0063] E1 is a high-entropy hydrogen-storage alloy containing
cobalt with a mole ratio equal to 0.
[0064] E2 is a high-entropy hydrogen-storage alloy containing
cobalt with a mole ratio equal to 0.5.
[0065] E3 is a high-entropy hydrogen-storage alloy containing
cobalt with a mole ratio equal to 0.75.
[0066] E4 is a high-entropy hydrogen-storage alloy containing
cobalt with a mole ratio equal to 1.0.
[0067] E5 is a high-entropy hydrogen-storage alloy containing
cobalt with a mole ratio equal to 1.25.
[0068] E6 is a high-entropy hydrogen-storage alloy containing
cobalt with a mole ratio equal to 1.5.
[0069] E7 is a high-entropy hydrogen-storage alloy containing
cobalt with a mole ratio equal to 2.0.
[0070] F1 is a high-entropy hydrogen-storage alloy containing iron
with a mole ratio equal to 0.5.
[0071] F2 is a high-entropy hydrogen-storage alloy containing iron
with a mole ratio equal to 1.0.
[0072] F3 is a high-entropy hydrogen-storage alloy containing iron
with a mole ratio equal to 1.25.
[0073] F4 is a high-entropy hydrogen-storage alloy containing iron
with a mole ratio equal to 1.5.
[0074] F5 is a high-entropy hydrogen-storage alloy containing iron
with a mole ratio equal to 2.0.
[0075] F6 is a high-entropy hydrogen-storage alloy containing iron
with a mole ratio equal to 2.5.
DETAILED DESCRIPTION OF THE INVENTION
[0076] The technical characteristics and preparation method of the
hydrogen-storage alloy of the present invention will become
apparent with the detailed description of preferred embodiments and
the illustration of related drawings as follows.
[0077] The hydrogen-storage alloy of the present invention has a
molecular formula of
Co.sub.uFe.sub.vMn.sub.wTi.sub.xV.sub.yZr.sub.z, wherein
0.5.ltoreq.u.ltoreq.2.0, 0.5.ltoreq.v.ltoreq.2.5,
0.5.ltoreq.w.ltoreq.2.0, 0.5.ltoreq.x.ltoreq.2.5,
0.4.ltoreq.y.ltoreq.3.0 and 0.4.ltoreq.z.ltoreq.3.0.
[0078] The first embodiment is provided to illustrate a common
method of preparing the hydrogen storage alloy of the present
invention, and an equivalent preparation method such as a
mechanical-alloying method can be used.
[0079] The hydrogen storage alloy of the present invention is cast
by melting pure metal lumps by a vacuum arc remelter (VAR) to
produce the alloy, wherein each pure metal is placed on a
water-cooled copper crucible, and then a vacuum pump is turned on
until the pressure reaches 2.times.10.sup.-2 torr, and a valve of
the pump is shut, and argon gas is pumped in repeatedly to maintain
the pressure at 200 ton, so as to assure a sufficiently low
pressure of oxygen in the furnace, such that only the argon gas
with a pressure lower than 1 atmosphere can be passed through and
ignited by an electric arc, and the metal is melted to a molten
form, and after the electric arc stirs the molten metal uniformly,
the power is turned off, and the alloy is turned upside down. The
aforementioned melting process is repeated for several times, and
the alloy is cooled completely and is taken out.
[0080] The second embodiment is provided to show the effect of
different titanium (Ti) contents.
[0081] With reference to FIG. 1 for the effect of specified metals
of different mole ratios on the properties of a hydrogen-storage
alloy, a specific metal content is adjusted while other metal
contents are fixed. For example, the hydrogen storage alloy of the
second embodiment has a molecular formula of
Co.sub.uFe.sub.vMn.sub.wTi.sub.xV.sub.yZr.sub.z wherein u, v, w, y
and z are fixed to 1, and the value x of (CoFeMnTi.sub.xVZr,
0.5.ltoreq.x.ltoreq.2.5) is adjusted, and we can observe the effect
of the titanium content on the properties of the hydrogen-storage
alloy.
[0082] Referred to FIGS. 2A to 4B, the range of changing the
titanium content is limited to the condition of
0.5.ltoreq.x.ltoreq.2.5, or atomic percentages used for indicating
the contents of the hydrogen-storage alloy, wherein the Ti content
falls within a range from 9.0 to 33.3 and the remaining contents
fall within a range from 13.3 to 18.2, and then crystal structure,
hydrogen absorption kinetics and hydrogen absorption/desorption
capacities are tested, and Designations A1 to A5 represent mole
ratios of 0.5, 1.0, 1.5, 2.0 and 2.5 of titanium in the
hydrogen-storage alloy, respectively. In the X-ray diffraction
patterns, we can observed that the hydrogen-storage alloy has a
C14-Laves phase, and the lattice increases as the titanium content
increases, and the peaks shift to the right, since the atomic
diameter of titanium is greater than the average atomic diameter of
other metals in the alloy. At different temperatures (25.degree. C.
and 80.degree. C.), the required time (t.sub.0.9) will increase
with the titanium content of the hydrogen-storage alloy when 90% of
the maximum hydrogen absorption capacity is reached, and become
smaller gradually, and then become greater gradually. At a lower
temperature (25.degree. C.), it takes a longer time to reach
t.sub.0.9. In the analysis of pressure-composition-isotherm (PCI)
curve, we can observe that if the titanium content increases at
25.degree. C. and 80.degree. C., the hydrogen affinity is improved,
so that the ratio of percentages by weight of all hydrogen atoms to
all alloy atoms (H/M value) will be increased, and the maximum
ratio of percentages by weight of all hydrogen atoms to all alloy
atoms (max H/M value) with the hydrogen storage capacity is 1.8.
The maximum (H/M) value at a low temperature is usually greater
than the maximum H/M value at high temperature, and this result
matches the theory of the hydrogen absorption being a heat
releasing reaction. However, if the mole ratio of titanium is 2.5,
the H/M value at different temperatures tends to drop, and the
maximum H/M value at 80.degree. C. is greater than the maximum H/M
value at 25.degree. C. The parameters of a lattice before/after a
PCI analysis and the volume expansion ratios of alloys with
different titanium contents are listed in Table 1 below.
TABLE-US-00001 TABLE 1 Parameters of Lattice Before/After PCI
Analysis and Volume Expansion Ratios of Alloys With Different
Titanium Contents Parameters of Parameters of Volume Titanium
Lattice Before Lattice After PCI Expansion Content PCI Analysis
Analysis Ratio (mole ratio) a (.ANG.) c (.ANG.) a (.ANG.) c (.ANG.)
(%) 0.5 5.212 8.687 5.273 8.562 0.87 1.0 4.958 8.046 4.982 8.152
2.30 1.5 5.236 8.776 5.303 8.789 2.73 2.0 5.255 8.804 5.413 9.903
19.40 2.5 5.286 8.867 5.522 9.801 20.63
[0083] The third embodiment is provided to show the effect of
different zirconium (Zr) contents.
[0084] With reference to FIG. 1 for the effect of different mole
ratios of zirconium on the properties of the hydrogen-storage
alloy, the zirconium content is adjusted and the other metal
contents are kept constant. In the hydrogen-storage alloy with the
molecular formula CoFeMnTiVZr.sub.z, the zirconium (Zr) content is
changed within the range of 0.4.ltoreq.z.ltoreq.3.0, or atomic
percentages are used for representing the contents of the hydrogen
storage alloy, wherein the Zr content falls within the range from
7.5 to 37.5 and the remaining contents fall within the range from
12.5 to 18.5, and crystal structure, hydrogen absorption kinetics
and hydrogen absorption/desorption capacity are tested, and the
Designations B1 to B9 represent the mole ratios 0.4, 0.7, 1.0, 1.3,
1.7, 2.0, 2.3, 2.6 and 3.0 of zirconium in the hydrogen-storage
alloy, respectively. In the X-ray diffraction patterns as shown in
FIGS. 5A, 5B, we can observe that the lattice increases with the
zirconium content, and thus the (110) peak shifts to the right, and
thus both titanium and zirconium have a significant effect to the
lattice parameters of the lattice. In FIG. 6, if the zirconium
content of the hydrogen-storage alloy is increased, the hydrogen
absorption capacity of the hydrogen-storage alloy will be enhanced,
and a drop of temperature of the environment of the reaction drops,
the hydrogen absorption capacity of the hydrogen-storage alloy will
be enhanced, too. In addition, the PCI analysis shows that the
volume of lattice will expand 23.83% (as shown in Table 2) if the
zirconium content of the hydrogen-storage alloy has a mole ratio
equal to 1.6. This result together with the X-ray diffraction
patterns can explain a hydrogen-storage alloy with high zirconium
content still contains large amount of retained hydrogen, and it
shows that the hydrogen-storage alloy has an excellent hydrogen
absorption capacity.
TABLE-US-00002 TABLE 2 Parameters of Lattice Before/After PCI
Analysis and Volume Expansion Ratios of Alloys With Different
Zirconium Contents Parameters of Parameters of Volume Zirconium
Lattice Before Lattice After PCI Expansion Content PCI Analysis
Analysis Ratio (mole ratio) a (.ANG.) c (.ANG.) a (.ANG.) c (.ANG.)
(%) 0.4 4.866 7.915 4.866 7.936 0.27 0.7 4.866 7.936 4.935 7.989
3.51 1.0 4.958 8.046 4.982 8.152 2.30 1.3 4.994 8.169 5.273 8.597
17.32 1.6 5.031 8.222 5.342 9.030 23.83 2.0 5.056 8.258 5.383 8.753
20.16 2.3 5.067 8.302 5.411 8.853 21.62 2.6 5.117 8.319 5.469 8.937
22.70 3.9 5.117 8.763 5.469 8.906 16.10
[0085] The fourth embodiment is provided to show the effect of
different vanadium (V) contents.
[0086] With reference to FIGS. 1, 7A, 7B and 8 for the effect of
different mole ratios of vanadium on the properties of the
hydrogen-storage alloy, the vanadium content is adjusted an the
other metal contents are kept constant. In the hydrogen-storage
alloy with the molecular formula CoFeMnTiV.sub.yZr, the vanadium
(V) content is changed within the range of 0.5.ltoreq.y.ltoreq.2.5,
or atomic percentages are used for representing the contents of the
hydrogen storage alloy, wherein the vanadium content falls within
the range from 9.0 to 33.3 and the remaining contents fall within
the range from 13.3 to 18.2, and crystal structure, hydrogen
absorption kinetics and hydrogen absorption/desorption capacity are
tested, and the Designations C1 to B9 represent the mole ratios
0.4, 0.7, 1.0, 1.3, 1.7, 2.0, 2.3, 2.6 and 3.0 of vanadium in the
hydrogen-storage alloy respectively. In the X-ray diffraction
patterns, we cannot observe any significant shift of each wave peak
caused by the hydrogen-storage alloy when the vanadium content is
increased, since the atomic diameter of the vanadium metal is
smaller than the titanium and zirconium metals and almost equal to
the average atomic diameter of the alloy. Therefore, the size of
the lattice will not be affected significantly (as shown in Table
3), and the hydrogen absorption capacity of alloys with different
vanadium contents will not be affected completely by temperature.
However, the enthalpy of formation between vanadium and hydrogen is
equal to -37.4 kJ/mol H.sub.2, and thus the alloy with high
vanadium content will release hydrogen easily.
TABLE-US-00003 TABLE 3 Parameters of Lattice Before/After PCI
Analysis and Volume Expansion Ratios of Alloys With Different
Vanadium Contents Parameters of Parameters of Volume Vanadium
Lattice Before Lattice After PCI Expansion Content PCI Analysis
Analysis Ratio (mole ratio) a (.ANG.) c (.ANG.) a (.ANG.) c (.ANG.)
(%) 0.4 4.958 8.095 5.006 8.137 2.47 0.7 4.970 8.113 4.982 8.127
0.66 1.0 4.958 8.046 4.982 8.152 2.30 1.3 4.958 8.095 4.994 8.169
2.39 1.6 4.970 8.135 5.006 8.290 3.40 2.0 4.958 8.095 4.982 8.203
2.31 2.3 4.958 8.095 5.043 8.163 4.32 2.6 4.970 8.135 5.043 8.240
4.29 3.9 4.970 8.113 5.043 8.240 4.57
[0087] The fifth embodiment is provided to show the effect of
different manganese (Mn) contents.
[0088] With reference to FIGS. 1, 9A, 9B and 10 for the effect of
different mole ratios of manganese on the properties of the
hydrogen-storage alloy, the manganese content is adjusted and the
other metal contents are kept constant. In the hydrogen-storage
alloy with the molecular formula CoFeMn.sub.wTiVZr, the manganese
(Mn) content is changed within the range of
0.5.ltoreq.w.ltoreq.2.0, or atomic percentages are used for
representing the contents of the hydrogen-storage alloy, wherein
the manganese content falls within the range from 9.0 to 28.6 and
the remaining contents fall within the range from 14.3 to 18.2, and
crystal structure, hydrogen absorption kinetics and hydrogen
absorption/desorption capacity are tested, and the Designations D1
to D7 represent the mole ratios 0, 0.5, 0.75, 1.0, 1.25, 1.5 and
2.0 0 of manganese in the hydrogen-storage alloy respectively.
Similarly, in the X-ray diffraction patterns, we cannot observe any
significant shift of each diffraction peak caused by the
hydrogen-storage alloy when the manganese content is increased,
since the atomic diameter of the manganese metal is also smaller.
In FIGS. 4A, 4B, the time required to reach 90% of the maximum
hydrogen absorption capacity is usually within 100 s, and the
maximum hydrogen absorption capacity and the maximum hydrogen
desorption capacity of the hydrogen-storage alloy are 1.94 wt % and
1.39 wt %, respectively.
TABLE-US-00004 TABLE 4 Properties of Hydrogen-Storage Alloys With
Different Manganese Contents at Different Temperatures Maximum
Effective Hydrogen Hydrogen Manganese Temper- Absorption Desorption
Content ature a c Capacity Capacity t.sub.0.9 (mole ratio) (K)
(.ANG.) (.ANG.) (wt %) (wt %) (s) 0 278 5.02 8.166 1.94 0.48 48 0.5
278 4.976 8.117 1.94 0.88 52 0.75 278 4.953 7.088 1.7 0.88 76 1.0
278 4.972 8.107 1.67 0.92 50 1.25 278 4.937 8.086 1.6 1.09 66 1.5
278 4.907 8.042 1.53 1.22 85 2.0 278 4.922 8.04 0.37 0.37 30 0 298
-- -- 1.76 0.68 54 0.5 298 -- -- 1.7 0.78 33 0.75 298 -- -- 1.63
1.08 42 1.0 298 -- -- 1.49 1.39 45 1.25 298 -- -- 1.56 1.39 58 1.5
298 -- -- 1.32 1.25 96 2.0 298 -- -- 0.24 0.24 -- 0 353 -- -- 1.54
0.87 57 0.5 353 -- -- 1.44 1.38 45 0.75 353 -- -- 1.38 1.38 73 1.0
353 -- -- 1.18 1.07 45 1.25 353 -- -- 1.04 1.01 58 1.5 353 -- --
0.71 0.67 96 2.0 353 -- -- 0 0 --
[0089] The sixth embodiment is provided to show the effect of
different cobalt (Co) contents.
[0090] Referred to FIGS. 1, 11A, 11B and 12 for the effect of
different mole ratios of cobalt on the properties of the
hydrogen-storage alloy, the cobalt content is adjusted and the
other metal contents are kept constant. In the hydrogen-storage
alloy with the molecular formula Co.sub.uFeMnTiVZr, the cobalt (Co)
content is changed within the range of 0.5.ltoreq.w.ltoreq.2.0, or
atomic percentages are used for representing the contents of the
hydrogen-storage alloy, wherein the cobalt content falls within the
range from 9.0 to 28.6 and the remaining contents fall within the
range from 14.3 to 18.2, and crystal structure, hydrogen absorption
kinetics and hydrogen absorption/desorption capacity are tested,
and the Designations E1 to E7 represent the mole ratios 0, 0.5,
0.75, 1.0, 1.25, 1.5 and 2.0 0 of cobalt in the hydrogen-storage
alloy respectively. Similarly, in the X-ray diffraction patterns,
we cannot observe any significant shift of each diffraction peak
caused by the hydrogen-storage alloy when the cobalt content is
increased, since the atomic diameter of the cobalt is also smaller.
In FIG. 5, the time required to reach 90% of the maximum hydrogen
absorption capacity has a significant difference caused by the
cobalt content, and thus the cobalt content of the hydrogen storage
alloy will affect the hydrogen absorption efficiency, and the
maximum hydrogen absorption capacity and the maximum hydrogen
desorption capacity of the hydrogen-storage alloy are 1.91 wt % and
1.39 wt %, respectively.
TABLE-US-00005 TABLE 5 Properties of Hydrogen-Storage Alloys With
Different Cobalt Contents at Different Temperatures Maximum
Effective Cobalt Hydrogen Hydrogen Content Temper- Absorption
Desorption (mole ature a c Capacity Capacity t.sub.0.9 ratio) (K)
(.ANG.) (.ANG.) (wt %) (wt %) (s) 0 278 5.04 8.23 2.01 0.51 22 0.5
278 4.987 8.123 1.91 0.54 36 0.75 278 4.976 8.118 1.91 0.71 38 1.0
278 4.972 8.107 1.67 0.92 50 1.25 278 4.944 8.044 1.29 1.22 242 1.5
278 4.917 8.006 0.64 0.56 163 2.0 278 4.902 7.978 0 0 -- 0 298 --
-- 1.83 0.37 21 0.5 298 -- -- 1.86 0.64 20 0.75 298 -- -- 1.76 0.85
32 1.0 298 -- -- 1.49 1.39 45 1.25 298 -- -- 1.25 1.22 182 1.5 298
-- -- 0.45 0.41 410 2.0 298 -- -- 0 0 -- 0 353 -- -- 1.75 0.54 20
0.5 353 -- -- 1.61 1.07 32 0.75 353 -- -- 1.54 1.28 50 1.0 353 --
-- 1.18 1.07 73 1.25 353 -- -- 0.6 0.57 382 1.5 353 -- -- 0 0 --
2.0 353 -- -- 0 0 --
[0091] The seventh embodiment 7 is provided to show the effect of
different iron (Fe) contents.
[0092] With reference to FIGS. 1, 13A, 13B and 14 for the effect of
different mole ratios of iron on the properties of the
hydrogen-storage alloy, the iron content is adjusted and the other
metal contents are kept constant. In the hydrogen-storage alloy
with the molecular formula CoFe.sub.vMnTiVZr, the iron (Fe) content
is changed within the range of 0.5.ltoreq.w.ltoreq.2.5, or atomic
percentages are used for representing the contents of the
hydrogen-storage alloy, wherein the iron content falls within the
range from 9.0 to 33.3 and the remaining contents fall within the
range from 13.3 to 18.2, and crystal structure, hydrogen absorption
kinetics and hydrogen absorption/desorption capacity are tested,
and the Designations F1 to F7 represent the mole ratios 0.5, 1.0,
1.25, 1.5, 2.0 and 2.5 of iron in the hydrogen storage alloy,
respectively. Similarly, in the X-ray diffraction patterns, we
cannot observe any significant shift of each intensity peak caused
by the hydrogen-storage alloy when the iron content is increased,
since the atomic diameter of the iron metal is also smaller.
[0093] In FIG. 6, the time required to reach 90% of the maximum
hydrogen absorption capacity may be affected at ambient temperature
by the iron content of the hydrogen-storage alloy easily. Changing
the iron content can achieve 1.97 wt % and 1.39 wt % for the
maximum hydrogen absorption capacity and the maximum hydrogen
desorption capacity of the hydrogen-storage alloy,
respectively.
TABLE-US-00006 TABLE 6 Properties of Hydrogen-Storage Alloys With
Different Iron Contents at Different Temperatures Maximum Effective
Iron Hydrogen Hydrogen Content Temper- Absorption Desorption (mole
ature a c Capacity Capacity t.sub.0.9 ratio) (K) (.ANG.) (.ANG.)
(wt %) (wt %) (s) 0 278 -- -- 1.97 0.34 28 0.5 278 -- -- 1.67 0.92
50 0.75 278 5.036 8.205 1.86 0.41 24 1.0 278 4.988 8.155 1.29 0.2
250 1.25 278 4.972 8.107 1.49 1.39 45 1.5 278 4.92 8.022 0.61 0.47
2500 2.0 278 4.914 8.061 0.14 0.1 -- 0 353 -- -- 1.68 0.64 32 0.5
353 -- -- 1.07 0.24 40 0.75 353 -- -- 1.49 1.39 73 1.0 353 -- --
1.11 0.81 50 1.25 353 -- -- 0.37 0.34 -- 1.5 353 -- -- 1.97 0.34 28
2.0 353 -- -- 1.67 0.92 50
[0094] In summation of the description above, the content of each
metal in the hydrogen-storage alloy of the present invention is
adjusted to achieve the hydrogen-storage alloy, such that the
hydrogen has excellent hydrogen absorption/desorption and
hydrogen-storage capacities in an operation environment at ambient
temperature and pressure, and the hydrogen-storage alloy has the
potential to become a green energy source.
[0095] Many changes and modifications in the above-described
embodiment of the invention can, of course, be carried out without
departing from the scope thereof Accordingly, to promote the
progress in science and the useful arts, the invention is disclosed
and is intended to limit only by the scope of the appended
claims.
* * * * *