Composition of timn2-based hydrogen storage alloy

Abstract

A composition of a TiMn2-based hydrogen storage alloy according to an embodiment of the present invention may be a composition including a component that reduces the relative contents of Ti, Mn, and Mn, wherein the component is at least one of Fe, Al, or Si, and reduces the hysteresis that occurs during hydrogen absorption and release.

Description

Composition of TIMN2-based hydrogen storage alloys

[0001] The present invention relates to a composition of an AB2-based hydrogen storage alloy, and more specifically, to a composition of a TiMn2-based hydrogen storage alloy in which hysteresis is reduced.

[0002]

[0003] Hydrogen is being studied as a new energy medium to replace fossil fuels, and its energy density per unit mass is very high compared to gasoline or liquefied natural gas; however, since hydrogen has a boiling point of -256.6°C and is a gas at room temperature and pressure, its storable energy density per unit volume is low.

[0004] Due to these problems, the efficient storage and transportation of hydrogen is a critical issue in the use of hydrogen.

[0005] Although various studies have recently been conducted on efficient hydrogen storage methods, for the stored hydrogen to be utilized, its release must be easy in terms of temperature, pressure, and absorption / release rates.

[0006] From this perspective, hydrogen storage using certain metal hydrides possesses excellent characteristics and has the advantages of high volumetric storage density and outstanding stability.

[0007] Representative examples of such hydrogen storage alloys developed include LaNi5, Mg2Ni, and AB2-type Laves phase alloys.

[0008] Although the LaNi5-based alloy developed above has excellent hydrogen absorption / release characteristics, its hydrogen storage capacity is low at about 1.5 wt%, making it difficult to apply as a hydrogen storage alloy, and it has the disadvantage of being economically unviable due to the high price of La.

[0009] In addition, Mg2Ni-based hydrogen storage alloys have a very large hydrogen storage capacity, but they have the disadvantage of being difficult to apply to room-temperature hydrogen storage media because the operating temperature is 200°C or higher.

[0010] Meanwhile, AB2-type Laves phase alloys are known to have a large hydrogen storage capacity and a fast hydrogenation reaction rate, making them suitable for applications such as hydrogen storage and heat pumps.

[0011] In this regard, US registered patent US 12077838 B2 (September 3, 2024) discloses a non-flammable hydrogen storage alloy and a hydrogen storage system using said alloy.

[0012] However, there is a demand in the field for the development of AB2-based hydrogen storage alloys that secure sufficient hydrogen storage capacity and possess excellent hysteresis and sloping characteristics.

[0013]

[0014] The present invention has been devised to solve the above-mentioned problems and aims to provide a hydrogen storage alloy in which hysteresis can be reduced through the composition of an AB2-based hydrogen storage alloy, more specifically, a TiMn2-based hydrogen storage alloy.

[0015]

[0016] The problems that the present invention aims to solve are not limited to those described above, and problems not mentioned will be clearly understood by those skilled in the art from this specification and the attached drawings.

[0017]

[0018] A composition of a TiMn2-based hydrogen storage alloy according to one embodiment of the present invention may be a composition of a TiMn2-based hydrogen storage alloy that includes a component that reduces the relative content of Ti, Mn, and Mn, wherein the component is at least one of Fe, Al, and Si, and reduces hysteresis occurring during the absorption and release of hydrogen.

[0019]

[0020] According to the composition of a TiMn2-based hydrogen storage alloy according to one embodiment of the present invention, the hysteresis can be reduced by including Fe, Al, and Si components that reduce the Mn content.

[0021] Accordingly, hydrogen storage alloys manufactured using the composition of TiMn2-based hydrogen storage alloys have the advantage of increasing the effective hydrogen storage capacity.

[0022] In addition, according to the composition of the TiMn2-based hydrogen storage alloy according to one embodiment of the present invention, by including Fe, Al, and Si components that reduce the Mn content, there is an advantage that the melting process cost can be reduced due to the relatively low Mn content.

[0023]

[0024] The effects of the present invention are not limited to the effects described above, and unmentioned effects will be clearly understood by those skilled in the art from this specification and the accompanying drawings.

[0025]

[0026] Figure 1 is an example diagram illustrating an AB2-based hydrogen storage alloy.

[0027] FIG. 2 is a PCT graph to explain that hysteresis is reduced by the composition of a TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention.

[0028] FIG. 3 is a PCT graph to explain that hysteresis is reduced through the relationship between Fe, Cr, and V constituting the composition of a TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention.

[0029] FIG. 4 is a graph for explaining how the effective hydrogen storage amount changes through the relationship between Fe, Cr, and V constituting the composition of the TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention.

[0030] FIG. 5 is a PCT graph to explain that hysteresis is reduced depending on the content of Si constituting the composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention.

[0031] FIG. 6 is a graph for explaining the ratio of flatness pressure during hydrogen absorption and release according to the content of Si constituting the composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention.

[0032] FIG. 7 is a graph illustrating that the effective hydrogen storage amount changes depending on the content of Si constituting the composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention.

[0033] FIG. 8 is a PCT graph to explain that hysteresis is reduced depending on the content of Al constituting the composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention.

[0034] FIG. 9 is a graph for explaining the ratio of flatness pressure during hydrogen absorption and release according to the content of Al constituting the composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention.

[0035] FIG. 10 is a graph illustrating that the effective hydrogen storage amount changes depending on the content of Al constituting the composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention.

[0036]

[0037] Specific embodiments of the present invention will be described in detail below with reference to the drawings. However, the concept of the present invention is not limited to the presented embodiments. Those skilled in the art who understand the concept of the present invention may easily propose other inventions that are inferior or other embodiments included within the scope of the concept of the present invention by adding, changing, or deleting other components within the same scope of the concept, and such are also to be considered to be included within the scope of the concept of the present invention.

[0038]

[0039] A composition of a TiMn2-based hydrogen storage alloy according to one embodiment of the present invention may be a composition of a TiMn2-based hydrogen storage alloy that includes a component that reduces the relative content of Ti, Mn, and Mn, wherein the component is at least one of Fe, Al, and Si, and reduces hysteresis occurring during the absorption and release of hydrogen.

[0040] In addition, the above components may further include Cr and V, and when the above components are Fe, the composition may be a TiMn2-based hydrogen storage alloy containing at least 20% of the content of Cr and V based on atomic percentage.

[0041] In such cases, for example, the above components may be a composition of a TiMn2-based hydrogen storage alloy that may further include, as components of the components, ferrochrome formed by the reaction of Fe and Cr instead of Fe and Cr, in addition to Fe and Cr.

[0042] As another example, the above component may be a composition of a TiMn2-based hydrogen storage alloy that may further include, as a component of the component, ferrovanadium formed by the reaction of Fe and V instead of Fe and V, in addition to Fe and V.

[0043] More specifically, the above composition may be a composition of a TiMn2-based hydrogen storage alloy satisfying the following chemical formula 1.

[0044] [Chemical Formula 1]

[0045] Ti A Zr B Mn C Fe D Cr E V F

[0046] A+B=1

[0047] 0.7≤A≤0.95

[0048] C+D+E+F=2

[0049] 0.8≤C≤1.5

[0050] 0 <E≤0.5

[0051] 0 <F≤0.5

[0052] 0.2(E+F)≤D

[0053] Meanwhile, the above composition may be a composition of a TiMn2-based hydrogen storage alloy that contains more than 0% and less than or equal to 5% of the total moles based on atomic percentage when the component is Si.

[0054] In such cases, the above composition may be a composition of a TiMn2-based hydrogen storage alloy satisfying the following chemical formula 2.

[0055] [Chemical Formula 2]

[0056] Ti A Zr B Mn C Fe D Cr E V F Si G

[0057] A+B=1

[0058] 0.7≤A≤0.95

[0059] C+D+E+F+G=2

[0060] 0.8≤C≤1.5

[0061] 0.1≤D≤0.4

[0062] 0.1≤E≤0.5

[0063] 0.1≤F≤0.5

[0064] 0 <G≤0.15

[0065] Meanwhile, the above composition may be a composition of a TiMn2-based hydrogen storage alloy that contains more than 0% and less than or equal to 5% of the total moles based on atomic percentage when the component is Al.

[0066] In such cases, the above composition may be a composition of a TiMn2-based hydrogen storage alloy satisfying the following chemical formula 3.

[0067] [Chemical Formula 3]

[0068] Ti A Zr B Mn C Fe D Cr E V F Al G

[0069] A+B=1

[0070] 0.7≤A≤0.95

[0071] C+D+E+F+G=2

[0072] 0.8≤C≤1.5

[0073] 0.1≤D≤0.4

[0074] 0.1≤E≤0.5

[0075] 0.1≤F≤0.5

[0076] 0 <G≤0.15

[0077]

[0078] Additionally, components with the same function within the scope of the same concept appearing in the drawings of each embodiment are described using the same reference numeral.

[0079]

[0080] Figure 1 is an example diagram illustrating an AB2-based hydrogen storage alloy.

[0081] FIG. 2 is a PCT graph to explain that hysteresis is reduced by the composition of a TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention.

[0082] Figure 3 is a PCT graph to explain how hysteresis is reduced through the relationship between Fe, Cr, and V constituting the composition of the TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention.

[0083] Figure 4 is a graph to explain how the effective hydrogen storage amount changes through the relationship between Fe, Cr, and V constituting the composition of the TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention.

[0084] Figure 5 is a PCT graph to explain that hysteresis is reduced depending on the content of Si constituting the composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention.

[0085] Figure 6 is a graph illustrating the ratio of flatness pressure during hydrogen absorption and release according to the content of Si constituting the composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention.

[0086] FIG. 7 is a graph illustrating that the effective hydrogen storage amount changes depending on the content of Si constituting the composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention.

[0087] FIG. 8 is a PCT graph to explain that hysteresis is reduced depending on the content of Al constituting the composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention.

[0088] FIG. 9 is a graph illustrating the ratio of flatness pressure during hydrogen absorption and release according to the content of Al constituting the composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention.

[0089] FIG. 10 is a graph illustrating that the effective hydrogen storage amount changes depending on the content of Al constituting the composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention.

[0090]

[0091] In order to express the technical concept of the present invention more clearly, the attached drawings have simplified or omitted parts that are less related to the technical concept of the present invention or that can be easily derived by those skilled in the art.

[0092]

[0093] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description.

[0094] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0095] In describing the present invention, if it is determined that a detailed description of related known technology may obscure the essence of the present invention, such detailed description is omitted.

[0096] A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0097] In this application, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0098]

[0099] AB2-based hydrogen storage alloys can refer to alloys that absorb hydrogen under specific temperature and pressure conditions as shown in Fig. 1 to become metal hydrides, and have the property of releasing hydrogen when pressure or temperature changes.

[0100] An example of the composition of the TiMn2-based hydrogen storage alloy according to the present invention (hereinafter referred to as the composition) was prepared using an arc melting method under vacuum and argon atmospheres. The alloy prepared experimentally as a sample was mechanically ground into powder, and then the hydrogenation reaction characteristics were measured using a Sievert-type PCT diagram measuring instrument, and the data were plotted.

[0101] Hereinafter, with reference to FIGS. 1 to 4, the composition of a TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention will be described in detail.

[0102]

[0103] <1st Example>

[0104] The composition according to the first embodiment of the present invention may, for example, mean a composition of a TiMn2-based hydrogen storage alloy satisfying the following chemical formula 1.

[0105] [Chemical Formula 1]

[0106] (Ti A Zr B )Mn C Fe D Cr E V F

[0107] Here, Ti is the element symbol for titanium, Zr is zirconium, Mn is manganese, Fe is iron, Cr is chromium, and V is vanadium.

[0108] In addition, A, B, C, D, and E of the above Chemical Formula 1 are each the atomic or mole fractions of the elements constituting the composition, where A+B=1, 0.7≤A≤0.95, C+D+E+F=2, 0.8≤C≤1.5, 0 <E≤0.5, 0<F≤0.5, 0.2(E+F)≤D의 조건을 만족하도록 한다.

[0109] To explain this in more detail, TiMn2-based hydrogen storage alloys have the disadvantage that as the Mn content ratio increases relatively, hysteresis—that is, the separation phenomenon where there is a difference between the absorption and release pressures of hydrogen—increases significantly, and not only does the flatness pressure increase, but the cost of the melting process also increases due to the generation of steam during melting.

[0110] Accordingly, the present invention enables the minimization of these disadvantages by adding a component to a TiMn2-based hydrogen storage alloy composition that includes Ti and Mn, but reduces the relative content of Mn.

[0111] The above components may be, for example, at least one of Fe, Al, Si, Cr, and V, and in the first embodiment, I will describe a composition that reduces hysteresis by controlling the content of Fe, Cr, and V.

[0112] FIG. 2 is according to a first embodiment of the present invention (Ti 0.9 Zr 0.1 )(Mn 1.3 Fe 0.3 Cr 0.1 V 0.3 ) and (Ti 0.9 Zr 0.1 )(Mn 1.5 Fe 0.1 Cr 0.1 V 0.3 This is a PCT graph at 30°C having the chemical formula of ).

[0113] In this way, the composition according to the first embodiment of the present invention establishes a relationship regarding the content of Fe, Cr, and V, and when this relationship is satisfied, hysteresis can be reduced.

[0114] More specifically, the composition according to the first embodiment of the present invention, when the content of Fe is 20% or more relative to the content of Cr and V based on atomic percentage (at %), reduces hysteresis, and as a result, allows the effective hydrogen storage capacity (wt%) to be relatively increased.

[0115] Figure 3 is a PCT graph to explain that hysteresis is reduced through the relationship between Fe, Cr, and V constituting the composition according to the first embodiment of the present invention.

[0116] As shown in FIG. 3, the inventors prepared hydrogen storage alloy samples with Fe content of 11% [Comparative Example 1], 18% [Comparative Example 2], 21% [Example 1], 27% [Example 2], and 32% [Example 3] relative to Cr and V content, and then calculated the PCT curve at 30°C.

[0117] As can be seen in FIG. 3, the composition according to the first embodiment of the present invention has a relatively high flatness pressure and a minimal reduction in hysteresis when the content of Fe is less than 20% relative to the content of Cr and V, whereas when the content of Fe is 20% or more relative to the content of Cr and V, it has a relatively low flatness pressure and a reduction in hysteresis.

[0118] That is, when the above composition contains Fe at a content of 20% or more relative to the content of Cr and V, it enables use in a safer environment due to relatively low flatness pressure, and at the same time reduces hysteresis, thereby improving the lifespan of the hydrogen storage alloy.

[0119] Figure 4 is a graph to explain how the effective hydrogen storage amount changes through the relationship between Fe, Cr, and V constituting the composition of the TiMn2-based hydrogen storage alloy according to the first embodiment of the present invention.

[0120] The inventors set the value of the pressure ratio for hydrogen absorption and release to "5" and calculated the effective hydrogen storage amount through the change in Fe content relative to Cr and V.

[0121] The above effective hydrogen storage capacity may refer to the hydrogen storage capacity corresponding to the difference between the absorption flat pressure and the emission flat pressure in the PCT graph.

[0122] The composition according to the first embodiment of the present invention allows for a significant increase in effective hydrogen storage capacity when the content of Fe is 20% or more relative to the content of Cr and V, as shown in FIG. 4.

[0123] That is, when the above composition contains Fe at a content of 20% or more relative to the content of Cr and V, compared to when it contains less than 20%, the flatness pressure is relatively lowered and hysteresis is relatively reduced, thereby improving the effective hydrogen storage capacity.

[0124] Meanwhile, in the composition according to the first embodiment of the present invention, if the content of Fe is 20% or more relative to the content of Cr and V, Fe and Cr can react to form ferrochrome (Fe-Cr), and Fe and V can react to form ferrovanadium (Fe-V).

[0125] By utilizing this, when the composition contains Fe at a content of 20% or more relative to the content of Cr and V, ferrochrome and ferrovanadium can be used as constituent elements instead of pure Fe, pure Cr, and pure V, thereby reducing the manufacturing cost of the hydrogen storage alloy.

[0126] That is, when the above composition contains Fe at a content of 20% or more relative to the content of Cr and V, ferrochrome and ferrovanadium can be substituted as components of the composition instead of pure Fe, Cr, and V.

[0127] Accordingly, the above composition has the advantage of improving economic efficiency compared to alloy compositions containing Fe, Cr, and V as pure materials in TiMn2-based hydrogen storage alloys.

[0128] That is, the composition according to the first embodiment of the present invention contains Fe at a content of 20% or more relative to the content of Cr and V, thereby relatively lowering the flatness pressure and relatively reducing hysteresis, while simultaneously enabling a reduction in manufacturing costs.

[0129]

[0130] Hereinafter, with reference to FIGS. 5 to 7, the composition of a TiMn2-based hydrogen storage alloy according to a second embodiment of the present invention will be described in detail.

[0131] However, I will omit the content that overlaps with what was explained in the first embodiment above.

[0132]

[0133] <2nd Example>

[0134] The composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention may, for example, mean a composition of the TiMn2-based hydrogen storage alloy satisfying the following chemical formula 2.

[0135] [Chemical Formula 2]

[0136] (Ti A Zr B )Mn C Fe D Cr E V F Si G

[0137] Here, Ti is the element symbol for titanium, Zr is zirconium, Mn is manganese, Fe is iron, Cr is chromium, V is vanadium, and Si is silicon.

[0138] In addition, A, B, C, D, and E in the above Chemical Formula 2 are each the atomic or mole fractions of the elements constituting the composition, wherein A+B=1, 0.7≤A≤0.95, C+D+E+F+G=2, 0.8≤C≤1.5, 0.1≤D≤0.4, 0.1≤E≤0.5, 0.1≤F≤0.5, 0 <G≤0.15의 조건을 만족하도록 한다.

[0139] To explain this in more detail, the composition according to the second embodiment of the present invention also includes components that reduce the relative content of Mn, namely Fe, Cr, V, and Si, so as to minimize the disadvantages associated with the Mn content.

[0140] The composition according to the second embodiment of the present invention may additionally include Si as a constituent element of the composition when compared to the composition according to the first embodiment.

[0141] Figure 5 is a PCT graph to explain that hysteresis is reduced depending on the content of Si constituting the composition of the TiMn2-based hydrogen storage alloy according to the second embodiment of the present invention.

[0142] The inventors confirmed that when Si is added to the composition of a TiMn2-based hydrogen storage alloy as shown in FIG. 5, hysteresis is reduced and flatness pressure can be changed. After preparing hydrogen storage alloy samples with different Si contents based on atomic percentage (at %), PCT curves at 30°C were calculated, and the chemical formula for the composition used in the experiment is as follows.

[0143] Si 2.0 at%: (Ti 0.74 Zr 0.26 )(Mn 1.1434 Fe 0.3 Cr 0.26 V 0.18 Si 0.06 ) [Example 4]

[0144] Si 3.5 at%: (Ti 0.74 Zr 0.26 )(Mn 1.1434 Fe 0.255 Cr 0.26 V 0.18 Si 0.105 ) [Example 5]

[0145] Si 5.0 at%: (Ti 0.74 Zr 0.26 )(Mn 1.1434 Fe 0.21 Cr 0.26 V 0.18 Si 0.15 ) [Example 6]

[0146] Si 7.0 at%: (Ti 0.74 Zr 0.26 )(Mn 1.1434 Fe 0.15 Cr 0.26 V 0.18 Si 0.21 ) [Comparative Example 3]

[0147] In addition, the substitution ratio of Si was calculated according to the following mathematical formula.

[0148] [Mathematical Formula]

[0149] (Si confiscation / Total confiscation) X 100

[0150]

[0151] For example, [Example 4] yields a substitution ratio of 2% by applying the above mathematical formula (0.06 / 3)X100.

[0152] As can be seen in FIG. 5, the composition according to the second embodiment of the present invention, when the Si content is greater than 0% and less than or equal to 5% of the total moles based on atomic percentage (at %), reduces hysteresis and allows the flatness pressure range to be relatively longer, thereby further improving the performance of the hydrogen storage alloy, i.e., the storage capacity.

[0153] Figure 6 is a graph illustrating the ratio of flat pressure during hydrogen absorption and release according to the content of Si constituting the composition according to the second embodiment of the present invention.

[0154] The inventors calculated the flat pressure ratio during hydrogen absorption and release according to the Si content as shown in Fig. 6, and it means that the larger the flat pressure ratio, the better the storage capacity of the hydrogen storage alloy.

[0155] As can be seen in Figure 6, the slope of the flatness ratio relative to the Si content decreased when the Si content (at %) relative to the total content was approximately 5%.

[0156] This means that when the Si content is 5% (at %) or less, the storage capacity of the hydrogen storage alloy is improved, and when it exceeds 5% (at %), the degree of improvement in the storage capacity of the hydrogen storage alloy is negligible.

[0157] Accordingly, the composition according to the second embodiment of the present invention satisfies a Si content (at %) of 5% or less relative to the total content, as shown in FIG. 6, thereby enabling the storage capacity of the hydrogen storage alloy to be improved.

[0158] FIG. 7 is a graph illustrating that the effective hydrogen storage amount changes depending on the content of Si constituting the composition according to the second embodiment of the present invention.

[0159] The inventors set the value of the pressure ratio for hydrogen absorption and release to "5" and calculated the effective hydrogen storage amount through the change in the Si content (at %) relative to the total content.

[0160] The inventors confirmed that when the Si content (at %) is 5% or less of the total content as shown in Fig. 7, the effective hydrogen storage capacity increases, and when the Si content (at %) is more than 5%, the effective hydrogen storage capacity decreases.

[0161] This is because, as shown in Fig. 5, when the Si content (at %) is 5% or less of the total content, the flattening pressure section becomes relatively longer, and when the Si content (at %) exceeds 5% of the total content, the flattening pressure section becomes relatively shorter.

[0162] As such, the composition according to the second embodiment of the present invention includes a Si content (at %) of 5% or less of the total content to reduce hysteresis and change the flatness pressure, and at the same time, allows the length of the flatness pressure section to be extended, thereby enabling a significant increase in the effective hydrogen storage capacity.

[0163]

[0164] Hereinafter, with reference to FIGS. 8 to 10, the composition of a TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention will be described in detail.

[0165] However, I will omit any content that overlaps with what was explained in the first and second embodiments above.

[0166]

[0167] <3rd Example>

[0168] The composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention may, for example, mean a composition of the TiMn2-based hydrogen storage alloy satisfying the following chemical formula 3.

[0169] [Chemical Formula 3]

[0170] (Ti A Zr B )Mn C Fe D Cr E V F Al G

[0171] Here, Ti is the element symbol for titanium, Zr is zirconium, Mn is manganese, Fe is iron, Cr is chromium, V is vanadium, and Al is aluminum.

[0172] In addition, A, B, C, D, and E in the above Chemical Formula 3 are each the atomic or mole fractions of the elements constituting the composition, where A+B=1, 0.7≤A≤0.95, C+D+E+F+G=2, 0.8≤C≤1.5, 0.1≤D≤0.4, 0.1≤E≤0.5, 0.1≤F≤0.5, 0 <G≤0.15의 조건을 만족하도록 한다.

[0173] To explain this in more detail, the composition according to the third embodiment of the present invention also includes components that reduce the relative content of Mn, namely Fe, Cr, V, and Al, so as to minimize the disadvantages associated with the Mn content.

[0174] The composition according to the third embodiment of the present invention may additionally include Al as a constituent element of the composition when compared to the composition according to the first embodiment, and may additionally include Al instead of Si as a constituent element of the composition when compared to the composition according to the second embodiment.

[0175] FIG. 8 is a PCT graph to explain that hysteresis is reduced depending on the content of Al constituting the composition of the TiMn2-based hydrogen storage alloy according to the third embodiment of the present invention.

[0176] As shown in FIG. 8, the inventors confirmed that when Al is added to the composition of a TiMn2-based hydrogen storage alloy, hysteresis is reduced and flatness pressure can be changed. After preparing hydrogen storage alloy samples with different Al contents based on atomic percentage (at %), PCT curves at 30°C were calculated, and the chemical formula for the composition used in the experiment is as follows.

[0177] Existing sample: (Ti 0.9 Zr 0.1 )(Mn 1.5 Fe 0.1 Cr 0.1 V 0.3 ) [Comparative Example 4]

[0178] Al 2.5 at%: (Ti 0.9 Zr 0.1 )(Mn 1.425 Fe 0.1 Cr 0.1 V 0.3 Al 0.075 ) [Example 7]

[0179] Al 5.0 at%: (Ti 0.9 Zr 0.1 )(Mn 1.35 Fe 0.1 Cr 0.1 V 0.3 Al 0.15 ) [Example 8]

[0180] Al 7.5 at%: (Ti 0.9 Zr 0.1 )(Mn 1.275 Fe 0.1 Cr 0.1 V 0.3 Al 0.225 ) [Comparative Example 5]

[0181] In addition, the substitution ratio of Al was calculated according to the following mathematical formula.

[0182] [Mathematical Formula]

[0183] (Si confiscation / Total confiscation) X 100

[0184]

[0185] For example, [Example 7] yields a substitution ratio of 2.5% by applying the above mathematical formula (0.075 / 3)X100.

[0186] As can be seen in FIG. 8, the composition according to the third embodiment of the present invention, when the content of Al is greater than 0% and less than or equal to 5% of the total moles based on atomic percentage (at %), reduces hysteresis and allows the flatness pressure range to be relatively longer, thereby further improving the performance of the hydrogen storage alloy, i.e., the storage capacity.

[0187] FIG. 9 is a graph for explaining the ratio of flat pressure during hydrogen absorption and release according to the content of Al constituting the composition according to the third embodiment of the present invention.

[0188] The inventors calculated the flat pressure ratio during hydrogen absorption and release according to the Al content as shown in Fig. 9, and it means that the larger the flat pressure ratio, the better the storage capacity of the hydrogen storage alloy.

[0189] As can be seen in Figure 9, the slope of the flat pressure ratio relative to the Al content decreased when the Al content (at %) relative to the total content was approximately 5%.

[0190] This means that when the Al content is 5% (at %) or less, the storage capacity of the hydrogen storage alloy is improved, and when it exceeds 5% (at %), the degree of improvement in the storage capacity of the hydrogen storage alloy is negligible.

[0191] Accordingly, the composition according to the third embodiment of the present invention satisfies the requirement that the content of Al (at %) relative to the total content is 5% or less, as shown in FIG. 9, thereby improving the storage capacity of the hydrogen storage alloy.

[0192] FIG. 7 is a graph illustrating that the effective hydrogen storage amount changes depending on the content of Si constituting the composition according to the second embodiment of the present invention.

[0193] The inventors set the value of the pressure ratio for hydrogen absorption and release to "5" and calculated the effective hydrogen storage amount through the change in the content of Al (at %) relative to the total content.

[0194] The inventors confirmed that when the content of Al (at %) is 5% or less of the total content as shown in FIG. 10, the effective hydrogen storage capacity increases, and when the content of Si (at %) is more than 5%, the effective hydrogen storage capacity decreases.

[0195] This is because, as shown in Fig. 8, when the Si content (at %) is 5% or less of the total content, the flattening pressure region becomes relatively longer, and when the Si content (at %) exceeds 5% of the total content, the flattening pressure region becomes relatively shorter.

[0196] As such, the composition according to the third embodiment of the present invention includes an Al content (at %) of 5% or less of the total content to reduce hysteresis and change the flatness pressure, and at the same time, by making the length of the flatness pressure section longer, the effective hydrogen storage capacity can be significantly increased.

[0197] However, although the composition according to the third embodiment has been described as being limited to having an Al content (at %) of 5% or less of the total content, it will be obvious to those skilled in the art that when both Si and Al are included, the content of Si and Al (at %) may be 5% or less of the total content, and the effect may also be included within the same or similar range.

[0198]

[0199] Although the structure and features of the present invention have been described above based on embodiments according to the present invention, the present invention is not limited thereto, and it is obvious to those skilled in the art that various changes or modifications can be made within the spirit and scope of the present invention; therefore, it is noted that such changes or modifications fall within the scope of the appended claims.

[0200] Furthermore, it is obvious that a hydrogen storage alloy produced by the composition of the above-mentioned TiMn2-based hydrogen storage alloy may also fall within the scope of the rights of the present invention.

Claims

1. In the composition of a TiMn2-based hydrogen storage alloy, The above composition is, It includes a component that reduces the relative content of Ti, Mn, and Mn, and The above components are, At least one of Fe, Al, and Si, and capable of reducing hysteresis generated during hydrogen absorption and release, Composition of TiMn2-based hydrogen storage alloy.

2. In Paragraph 1, The above components are, It further includes Cr and V, If the above component is Fe, Based on atomic percentage, Containing 20% ​​or more of Cr and V content, Composition of TiMn2-based hydrogen storage alloy.

3. In Paragraph 2, The above components are, Ferrochrome can be substituted for the above Fe and above Cr, Composition of TiMn2-based hydrogen storage alloys.

4. In Paragraph 2, The above components are, The above Fe and the above V can be replaced with ferrovanadium, Composition of TiMn2-based hydrogen storage alloys.

5. In Paragraph 2, The above composition is, Satisfying the following chemical formula 1, Composition of TiMn2-based hydrogen storage alloy. [Chemical Formula 1] You A Zr B Mn C Fe D Cr E V F A+B=1 0.7≤A≤0.95 C+D+E+F=2 0.8≤C≤1.5 0<E≤0.5 0<F≤0.5 0.2(E+F)≤D 6. In Paragraph 1, The above components are, It further includes Cr and V, If the above component is Si, Based on atomic percentage, Including more than 0% and not more than 5% of the total forfeiture Composition of TiMn2-based hydrogen storage alloys.

7. In Paragraph 6, The above composition is, Satisfying the following chemical formula 2, Composition of TiMn2-based hydrogen storage alloy. [Chemical Formula 2] You A Zr B Mn C Fe D Cr E V F Yes G A+B=1 0.7≤A≤0.95 C+D+E+F+G=2 0.8≤C≤1.5 0.1≤D≤0.4 0.1≤E≤0.5 0.1≤F≤0.5 0<G≤0.15 8. In Paragraph 1, The above components are, It further includes Cr and V, If the above component is Al, Based on atomic percentage, Including more than 0% and not more than 5% of the total forfeiture Composition of TiMn2-based hydrogen storage alloys.

9. In Paragraph 8, The above composition is, Satisfying the following chemical formula 3, Composition of TiMn2-based hydrogen storage alloy. [Chemical Formula 3] You A Zr B Mn C Fe D Cr E V F Al G A+B=1 0.7≤A≤0.95 C+D+E+F+G=2 0.8≤C≤1.5 0.1≤D≤0.4 0.1≤E≤0.5 0.1≤F≤0.5 0<G≤0.15 10. A hydrogen storage alloy manufactured from a composition according to any one of claims 1 to 9.

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