JP2007046133A - Hydrogen storage alloy and method for producing the same, hydrogen storage alloy electrode and secondary battery - Google Patents
Hydrogen storage alloy and method for producing the same, hydrogen storage alloy electrode and secondary battery Download PDFInfo
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- 239000001257 hydrogen Substances 0.000 title claims abstract description 158
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 158
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 151
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 138
- 239000000956 alloy Substances 0.000 title claims abstract description 138
- 238000003860 storage Methods 0.000 title claims abstract description 138
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- 239000013078 crystal Substances 0.000 claims abstract description 38
- 239000000203 mixture Substances 0.000 claims abstract description 28
- 229910010380 TiNi Inorganic materials 0.000 claims abstract description 27
- 239000000126 substance Substances 0.000 claims abstract description 27
- 229910003266 NiCo Inorganic materials 0.000 claims abstract description 22
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 17
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 14
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 11
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 11
- 229910052802 copper Inorganic materials 0.000 claims abstract description 11
- 229910052742 iron Inorganic materials 0.000 claims abstract description 11
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 11
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 11
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims abstract description 9
- 150000001342 alkaline earth metals Chemical group 0.000 claims abstract description 9
- 229910004247 CaCu Inorganic materials 0.000 claims abstract description 7
- 239000012298 atmosphere Substances 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 5
- 230000003578 releasing effect Effects 0.000 abstract description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 38
- 239000002245 particle Substances 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 15
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 14
- 239000011164 primary particle Substances 0.000 description 12
- 229910001122 Mischmetal Inorganic materials 0.000 description 10
- 238000000137 annealing Methods 0.000 description 10
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- 238000005259 measurement Methods 0.000 description 5
- -1 nickel metal hydride Chemical class 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 239000012300 argon atmosphere Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 150000002431 hydrogen Chemical class 0.000 description 4
- 229910052746 lanthanum Inorganic materials 0.000 description 4
- 229910052749 magnesium Inorganic materials 0.000 description 4
- 238000010298 pulverizing process Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 229910052684 Cerium Inorganic materials 0.000 description 3
- 229910052779 Neodymium Inorganic materials 0.000 description 3
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- 238000004458 analytical method Methods 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000008151 electrolyte solution Substances 0.000 description 3
- 229910052987 metal hydride Inorganic materials 0.000 description 3
- 239000012768 molten material Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 2
- 229910018007 MmNi Inorganic materials 0.000 description 2
- 229910000905 alloy phase Inorganic materials 0.000 description 2
- 229910052790 beryllium Inorganic materials 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
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- 238000007599 discharging Methods 0.000 description 1
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- 239000001307 helium Substances 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- NPURPEXKKDAKIH-UHFFFAOYSA-N iodoimino(oxo)methane Chemical compound IN=C=O NPURPEXKKDAKIH-UHFFFAOYSA-N 0.000 description 1
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- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
【課題】水素吸蔵合金の水素放出作用を改善した水素吸蔵合金の製造法及び該水素吸蔵合金を用いた二次電池を提供する。
【解決手段】化学組成が、一般式Ｒ１vＴｉxＲ２yＲ３z（但し、０＜ｖ、１≦ｘ≦５、２≦ｙ≦４．５、７５≦ｚ≦８３、ｖ＋ｘ＋ｙ＋ｚ＝１００であり、Ｒ１はＹを含む希土類元素、Ｒ２はアルカリ土類金属、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ａｌ、Ｃｕ、Ｆｅ、ＣｒおよびＳｉからなる群から選択される１種又は２種以上の元素である）で表され、ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相を有し、且つ、ＣａＣｕ5型結晶構造からなるＲ１Ｒ３5相、およびＰｕＮｉ3型結晶構造からなる（Ｒ１aＴｉbＲ２c）Ｒ３3相（但し、ａ＞０、ｂ＞０、ｃ＞０、ａ＋ｂ＋ｃ＝１）を有する水素吸蔵合金による。
【選択図】なしThe present invention provides a method for producing a hydrogen storage alloy in which the hydrogen releasing action of the hydrogen storage alloy is improved, and a secondary battery using the hydrogen storage alloy.
The chemical composition is represented by the general formula R1 v Ti x R2 y R3 z (where 0 <v, 1 ≦ x ≦ 5, 2 ≦ y ≦ 4.5, 75 ≦ z ≦ 83, v + x + y + z = 100). , R1 is a rare earth element containing Y, R2 is an alkaline earth metal, R3 is one or more elements selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Cr and Si R1R3 5 phase having a TiNi 3 phase or Ti (NiCo) 3 phase and having a CaCu 5 type crystal structure, and (R1 a Ti b R2 c ) R3 3 having a PuNi 3 type crystal structure According to a hydrogen storage alloy having phases (where a> 0, b> 0, c> 0, a + b + c = 1).
[Selection figure] None
Description
本発明は、水素吸蔵合金とその製造方法、並びに、水素吸蔵合金電極および該水素吸蔵合金電極を備えた二次電池に関する。 The present invention relates to a hydrogen storage alloy, a method for producing the same, a hydrogen storage alloy electrode, and a secondary battery including the hydrogen storage alloy electrode.
水素吸蔵合金は、安全に、かつ容易にエネルギー源としての水素を貯蔵できる合金であり、新しいエネルギー変換及び貯蔵用材料として非常に注目されている。
機能性材料としての水素吸蔵合金の応用分野は、水素の貯蔵・輸送、熱の貯蔵・輸送、熱−機械エネルギーの変換、水素の分離・精製、水素同位体の分離、水素を活物質とした電池、合成化学における触媒、温度センサーなどの広範囲にわたって提案されている。
The hydrogen storage alloy is an alloy that can safely and easily store hydrogen as an energy source, and has attracted much attention as a new energy conversion and storage material.
Applications of hydrogen storage alloys as functional materials include hydrogen storage and transport, heat storage and transport, thermal-mechanical energy conversion, hydrogen separation and purification, hydrogen isotope separation, and hydrogen as the active material It has been proposed over a wide range of applications, including batteries, catalysts in synthetic chemistry, and temperature sensors.
例えば、水素吸蔵合金を負極材料に使用したニッケル水素蓄電池は、（ａ）高容量であること、（ｂ）過充電・過放電に強いこと、（ｃ）高率充放電が可能であること、（ｄ）クリーンであること、などの特長を持つため、民生用電池として注目され、また、その応用・実用化が活発に行われている。
このように、水素吸蔵合金は、機械的、物理的、化学的に様々な応用の可能性を秘めており、将来の産業におけるキー材料の一つとして挙げられるものである。
For example, a nickel metal hydride storage battery using a hydrogen storage alloy as a negative electrode material is (a) high capacity, (b) strong against overcharge / overdischarge, (c) capable of high rate charge / discharge, (D) It has a feature such as being clean, and has attracted attention as a consumer battery, and its application / practical use has been actively conducted.
Thus, the hydrogen storage alloy has the potential for various mechanical, physical and chemical applications, and is one of the key materials in the future industry.
そして、このような水素吸蔵合金の一応用例であるニッケル水素蓄電池の電極材として、例えば、ＣａＣｕ5型結晶構造のＬａＮｉ5もしくはＭｍＮｉ5（Ｍｍ：ミッシュメタル：希土類元素の混合物）などで示されるＡＢ5型希土類系合金が数多く提案されている（例えば、特許文献１など）。
しかし、前記ＣａＣｕ5型結晶構造のＬａＮｉ5もしくはＭｍＮｉ5などで示されるＡＢ5型希土類系合金をニッケル水素蓄電池の電極として用いた場合には、放電電流を大きくした際の放電容量が低下し易いという問題を有しており、水素吸蔵合金の水素吸蔵放出機能をさらに改善することが要望されている。
As an electrode material of a nickel metal hydride storage battery which is one application example of such a hydrogen storage alloy, for example, AB indicated by LaNi 5 or MmNi 5 (Mm: Misch metal: mixture of rare earth elements) having a CaCu 5 type crystal structure, etc. Many type 5 rare earth alloys have been proposed (for example, Patent Document 1).
However, when an AB 5 type rare earth alloy represented by LaNi 5 or MmNi 5 having the CaCu 5 type crystal structure is used as an electrode of a nickel metal hydride storage battery, the discharge capacity when the discharge current is increased is likely to decrease. Therefore, it is desired to further improve the hydrogen storage / release function of the hydrogen storage alloy.
また、高容量の水素吸蔵合金を得るために、ＬａやＬａリッチのミッシュメタル（Ｌｍ）、ミッシュメタル（Ｍｍ）およびＭｇ、Ｎｉを主構成元素とし、ＰｕＮｉ3型の結晶構造を有する相を主相とする水素吸蔵合金が提案され、公知文献の実施例に記載されている（例えば特許文献２および３） In order to obtain a high-capacity hydrogen storage alloy, La and La-rich misch metal (Lm), misch metal (Mm), and Mg and Ni are main constituent elements, and a phase having a PuNi 3 type crystal structure is mainly used. Hydrogen storage alloys as phases are proposed and described in examples of known literature (for example, Patent Documents 2 and 3)
しかしながら、該提案に係る水素吸蔵合金を適用した水素吸蔵電極は、水素吸蔵合金が高容量ではあるものの、水素を放出し難い（放出速度が遅い）ためか高率放電特性に劣るという問題があり、加えて、アルカリ電解液に対する耐食性に劣るためかサイクル特性が十分でないという問題があった。 However, the hydrogen storage electrode to which the hydrogen storage alloy according to the proposal is applied has a problem that although the hydrogen storage alloy has a high capacity, it is difficult to release hydrogen (the release speed is slow) or the high rate discharge characteristic is inferior. In addition, there is a problem that the cycle characteristics are not sufficient because of poor corrosion resistance to the alkaline electrolyte.
また、前記Ｌａリッチのミッシュメタル（Ｌｍ）、ミッシュメタル（Ｍｍ）、Ｍｇ、Ｎｉを主構成元素とし、Ｔｉおよび他の元素を含有する水素吸蔵合金が提案され、公知文献の実施例に記載されている（例えば特許文献２、特許文献４〜６）。 In addition, hydrogen-absorbing alloys containing the La-rich misch metal (Lm), misch metal (Mm), Mg, and Ni as main constituent elements and containing Ti and other elements have been proposed and described in the examples of known literature. (For example, Patent Document 2 and Patent Documents 4 to 6).
しかしながら、これらの特許文献に提案されている水素吸蔵合金を適用した水素吸蔵電極は、共通して高率放電特性が劣るという欠点がある。 However, the hydrogen storage electrodes to which the hydrogen storage alloys proposed in these patent documents are applied have the disadvantage that the high rate discharge characteristics are inferior in common.
本発明は、上記問題点に鑑み、水素吸蔵合金の水素放出作用を改善することを一の課題とし、該水素吸蔵合金を用いた二次電池の特性を改善することを他の課題とする。 In view of the above problems, it is an object of the present invention to improve the hydrogen releasing action of a hydrogen storage alloy, and to improve the characteristics of a secondary battery using the hydrogen storage alloy.
本発明者らは、上記課題を解決するために鋭意研究を重ねた結果、上記特許文献には一切開示されていない相であって、水素吸蔵作用を有しないＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相が存在することにより、水素吸蔵合金の水素の放出を促進させ得ること、及びＰｕＮｉ3型結晶構造を有することにより水素吸蔵合金の水素吸蔵容量の低下を防止し得ることを見出し、本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the inventors of the present invention are TiNi 3 phase or Ti (NiCo) 3 that is a phase that is not disclosed at all in the above patent document and does not have a hydrogen storage function. It has been found that the presence of the phase can promote the release of hydrogen from the hydrogen storage alloy, and the decrease in the hydrogen storage capacity of the hydrogen storage alloy can be prevented by having a PuNi 3 type crystal structure. It came to be completed.
即ち、本発明は、化学組成が、一般式Ｒ１vＴｉxＲ２yＲ３z（但し、０＜ｖ、１≦ｘ≦５、２≦ｙ≦４．５、７５≦ｚ≦８３、ｖ＋ｘ＋ｙ＋ｚ＝１００であり、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ２はアルカリ土類金属から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ａｌ、Ｃｕ、Ｆｅ、ＣｒおよびＳｉからなる群から選択される１種又は２種以上の元素である）で表される水素吸蔵合金であって、ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相を有し、且つ、ＣａＣｕ5型結晶構造からなるＲ１Ｒ３5相（但し、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ、ＳｉおよびＡｌからなる群から選択される１種又は２種以上の元素である）、およびＰｕＮｉ3型結晶構造からなる（Ｒ１aＴｉbＲ２c）Ｒ３3相（但し、ａ＞０、ｂ＞０、ｃ＞０、ａ＋ｂ＋ｃ＝１であり、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ２はアルカリ土類金属から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ、ＳｉおよびＡｌからなる群から選択される１種又は２種以上の元素である）を有することを特徴とする水素吸蔵合金を提供する。 That is, the present invention has a chemical composition of the general formula R1 v Ti x R2 y R3 z (where 0 <v, 1 ≦ x ≦ 5, 2 ≦ y ≦ 4.5, 75 ≦ z ≦ 83, v + x + y + z = 100). R1 is one or more elements selected from rare earth elements including Y, R2 is one or more elements selected from alkaline earth metals, R3 is Ni, A hydrogen storage alloy represented by a TiNi 3 phase or Ti (NiCo), which is represented by one or more elements selected from the group consisting of Co, Mn, Al, Cu, Fe, Cr and Si) R1R3 5 phase having three phases and having a CaCu 5 type crystal structure (where R1 is one or more elements selected from rare earth elements including Y, and R3 is Ni, Co, Mn Selected from the group consisting of Fe, Cu, Cr, Si and Al One or more elements), and PuNi a three type crystal structure (R1 a Ti b R2 c) R3 3 -phase (except in a> 0, b> 0, c> 0, a + b + c = 1 R1 is one or more elements selected from rare earth elements including Y, R2 is one or more elements selected from alkaline earth metals, and R3 is Ni, Co , Mn, Fe, Cu, Cr, Si, and Al, which is one or more elements selected from the group consisting of Al).
本発明に係る水素吸蔵合金は、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相からなる複数の単結晶、Ｒ１Ｒ３5相からなる複数の単結晶および（Ｒ１aＴｉbＲ２c）Ｒ３3相からなる複数の単結晶（本明細書において、このような単結晶を一次粒子ともいい、単結晶と単結晶との境界を粒界ともいう）が混ざり合った集合体である。
前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相は、それ自身は水素を吸蔵するものではないが、上記のようなＲ１Ｒ３5相および（Ｒ１aＴｉbＲ２c）Ｒ３3相の水素吸蔵反応および水素放出反応において触媒作用を発揮するものと推測され、この相が、Ｒ１Ｒ３5相や（Ｒ１aＴｉbＲ２c）Ｒ３3相と混ざり合って存在することが水素の吸蔵および放出を促進するものと考えられる。また、ＴｉＮｉ3相やＴｉ（ＮｉＣｏ）3相は導電性を有しており、Ｒ１Ｒ３5相や（Ｒ１aＴｉbＲ２c）Ｒ３3相からなる一次粒子の粒界に介在して集電機能を発揮しているものと考えられる。
したがって、本発明によれば、特に水素の放出速度が速い場合（即ち、二次電池に使用された際においては放電電流が大きい場合）にも水素吸蔵合金からの水素の放出を促進させることができる。よって、該水素吸蔵合金を用いた二次電池は、レート特性に優れたものとなる。
The hydrogen storage alloy according to the present invention comprises a plurality of single crystals composed of the TiNi 3 phase or Ti (NiCo) 3 phase, a plurality of single crystals composed of the R1R3 5 phase, and a (R1 a Ti b R2 c ) R3 3 phase. It is an aggregate in which a plurality of single crystals (in this specification, such a single crystal is also referred to as a primary particle, and a boundary between the single crystal and the single crystal is also referred to as a grain boundary).
The TiNi 3 phase or Ti (NiCo) 3 phase itself does not occlude hydrogen, but the hydrogen occlusion reaction and hydrogen of the R1R3 5 phase and (R1 a Ti b R2 c ) R3 3 phase as described above. It is presumed that it exerts a catalytic action in the release reaction, and this phase is mixed with the R1R3 5 phase and the (R1 a Ti b R2 c ) R3 3 phase to promote hydrogen occlusion and release. Conceivable. Further, the TiNi 3 phase and the Ti (NiCo) 3 phase have conductivity, and the current collecting function is interposed between the grain boundaries of the primary particles composed of the R1R3 5 phase and the (R1 a Ti b R2 c ) R3 3 phase. It is considered that
Therefore, according to the present invention, it is possible to promote the release of hydrogen from the hydrogen storage alloy even when the hydrogen release rate is particularly high (that is, when the discharge current is large when used in a secondary battery). it can. Therefore, the secondary battery using the hydrogen storage alloy has excellent rate characteristics.
さらに、前記（Ｒ１aＴｉbＲ２c）Ｒ３3相は電解液に対する耐食性が劣り、Ｒ１Ｒ３5相は電解液に対する耐食性は優れるが、水素吸蔵量の点では前記（Ｒ１aＴｉbＲ２c）Ｒ３3相に劣るという特性があるところ、本発明に係る水素吸蔵合金は、これらＲ１Ｒ３5相と（Ｒ１aＴｉbＲ２c）Ｒ３3相とが混ざり合った状態で存在するので、（Ｒ１aＴｉbＲ２c）Ｒ３3相と電解液との接触が制約され、（Ｒ１aＴｉbＲ２c）Ｒ３3相の腐食が抑制されることによって合金の腐食も抑制され、二次電池の水素吸蔵合金電極に適用した場合にも耐久性に優れたものとなると考えられる。 Further, the (R1 a Ti b R2 c ) R3 3 phase is inferior in corrosion resistance to the electrolytic solution, and the R1R3 5 phase is excellent in corrosion resistance to the electrolytic solution, but in terms of the hydrogen storage amount, the (R1 a Ti b R2 c ) R3 Since the hydrogen storage alloy according to the present invention has a characteristic that it is inferior to the three phases, the R1R3 5 phase and the (R1 a Ti b R2 c ) R3 3 phase exist in a mixed state, so that (R1 a Ti b R2 c ) The contact between the R3 3 phase and the electrolyte is restricted, and the corrosion of the (R1 a Ti b R2 c ) R3 3 phase is suppressed, so that the corrosion of the alloy is also suppressed. Even when applied to an electrode, it is considered to be excellent in durability.
また、本発明に係る水素吸蔵合金は、好ましくは、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相を、４〜１４重量％含んでなる。
また、本発明に係る水素吸蔵合金は、好ましくは、前記（Ｒ１aＴｉbＲ２c）Ｒ３3相のａ軸長が、５．０１６〜５．０２５Åである。
The hydrogen storage alloy according to the present invention preferably contains 4 to 14% by weight of the TiNi 3 phase or Ti (NiCo) 3 phase.
In the hydrogen storage alloy according to the present invention, preferably, the (R1 a Ti b R2 c ) R3 3 phase has an a-axis length of 5.016 to 5.025 mm.
（Ｒ１aＴｉbＲ２c）Ｒ３3相は、ＰｕＮｉ３型結晶構造を有し、水素吸蔵量が大（即ち、高容量）であり、該相を含有させることによって高容量を確保することができ、特に該相のａ軸長を５．０１６〜５．０２５Åとすると高容量を維持しつつ水素の放出が容易になるため、優れた高率放電特性を得ることができる。 The (R1 a Ti b R2 c ) R3 3 phase has a PuNi3 type crystal structure, has a large hydrogen storage amount (ie, high capacity), and a high capacity can be secured by containing the phase. In particular, when the a-axis length of the phase is 5.016 to 5.025 mm, hydrogen can be easily released while maintaining a high capacity, so that excellent high rate discharge characteristics can be obtained.
また、本発明は、溶融状態にある合金を１０００Ｋ／秒以上の冷却速度で急冷凝固して鋳造し、かつ、この鋳造物が加圧状態の不活性ガス雰囲気下において焼鈍することにより、請求項１〜３の何れか一項に記載の水素吸蔵合金を製造することを特徴とする水素吸蔵合金の製造方法を提供する。また、好ましくは、焼鈍する際の圧力を０．１ＭＰａ（ゲージ圧）の加圧状態とする。 Further, the present invention claims that an alloy in a molten state is rapidly solidified and cast at a cooling rate of 1000 K / second or more, and the cast is annealed in a pressurized inert gas atmosphere. The manufacturing method of the hydrogen storage alloy characterized by manufacturing the hydrogen storage alloy as described in any one of 1-3. Preferably, the pressure at the time of annealing is set to a pressurized state of 0.1 MPa (gauge pressure).
さらに、本発明は、上記のような水素吸蔵合金を含むことを特徴とする水素吸蔵合金電極を提供する。さらに、本発明は、該水素吸蔵合金電極を備えたことを特徴とする二次電池を提供する。 Furthermore, this invention provides the hydrogen storage alloy electrode characterized by including the above hydrogen storage alloys. Furthermore, the present invention provides a secondary battery comprising the hydrogen storage alloy electrode.
本発明に係る水素吸蔵合金は、Ｔｉを添加してＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相を生成させたことにより、水素吸蔵容量及び水素放出作用が改善されたものとなり、また、該水素吸蔵合金を用いた本発明の二次電池は、放電容量及びレート特性に優れたものとなる。 The hydrogen storage alloy according to the present invention has an improved hydrogen storage capacity and hydrogen release action by adding Ti to produce a TiNi 3 phase or a Ti (NiCo) 3 phase. The secondary battery of the present invention using an alloy has excellent discharge capacity and rate characteristics.
本発明に係る水素吸蔵合金は、化学組成が、一般式Ｒ１vＴｉxＲ２yＲ３z（但し、０＜ｖ、１≦ｘ≦５、２≦ｙ≦４．５、７５≦ｚ≦８３、ｖ＋ｘ＋ｙ＋ｚ＝１００であり、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ２はアルカリ土類金属から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ａｌ、Ｃｕ、Ｆｅ、ＣｒおよびＳｉからなる群から選択される１種又は２種以上の元素である）で表される水素吸蔵合金であって、
ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相を有し、且つ、
ＣａＣｕ5型結晶構造からなるＲ１Ｒ３5相（但し、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ、ＳｉおよびＡｌからなる群から選択される１種又は２種以上の元素である）、
およびＰｕＮｉ3型結晶構造からなる（Ｒ１aＴｉbＲ２c）Ｒ３3相（但し、ａ＞０、ｂ＞０、ｃ＞０、ａ＋ｂ＋ｃ＝１であり、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ２はアルカリ土類金属から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ、ＳｉおよびＡｌからなる群から選択される１種又は２種以上の元素である）
を有する。
The hydrogen storage alloy according to the present invention has a chemical composition of the general formula R1 v Ti x R2 y R3 z (where 0 <v, 1 ≦ x ≦ 5, 2 ≦ y ≦ 4.5, 75 ≦ z ≦ 83, v + x + y + z = 100, R1 is one or more elements selected from rare earth elements including Y, R2 is one or more elements selected from alkaline earth metals, R3 Is one or more elements selected from the group consisting of Ni, Co, Mn, Al, Cu, Fe, Cr and Si),
Having a TiNi 3 phase or Ti (NiCo) 3 phase, and
R1R3 5 phase having a CaCu 5 type crystal structure (where R1 is one or more elements selected from rare earth elements including Y, and R3 is Ni, Co, Mn, Fe, Cu, Cr, Si) And one or more elements selected from the group consisting of Al)
And PuNi of 3 type crystal structure (R1 a Ti b R2 c) R3 3 -phase (where, a> 0, b> 0 , c> a 0, a + b + c = 1, R1 is selected from rare earth elements including Y R2 is one or more elements selected from alkaline earth metals, and R3 is Ni, Co, Mn, Fe, Cu, Cr, Si, and Al. Or one or more elements selected from the group consisting of
Have
ＴｉＮｉ3相或いはＴｉ（ＮｉＣｏ）3相は、生成相の粒界に析出し、水素吸蔵合金において水素化触媒機能や内部集電機能を発揮するものと考えられる。
ここで、Ｔｉ（ＮｉＣｏ）3相は、ＴｉＮｉ3相と同じ結晶構造を有し、Ｎｉの一部がＣｏに置換されてなる相である。尚、本発明において、Ｎｉに対するＣｏの比率は特に限定されるものではないが、一般的にはＮｉに対するＣｏの比が、１：０．０６〜１：０．１５である。
It is considered that the TiNi 3 phase or Ti (NiCo) 3 phase precipitates at the grain boundary of the generated phase and exhibits a hydrogenation catalyst function and an internal current collecting function in the hydrogen storage alloy.
Here, the Ti (NiCo) 3 phase has the same crystal structure as the TiNi 3 phase, and a part of Ni is substituted with Co. In the present invention, the ratio of Co to Ni is not particularly limited, but in general, the ratio of Co to Ni is 1: 0.06 to 1: 0.15.
本発明の水素吸蔵合金においては、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相が、４〜１４重量％の範囲で含まれていることが好ましい。ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相の含有量が、４重量％未満であれば、水素放出反応における触媒作用が十分に発揮されず放電特性の改善が不十分となるおそれがあり、また、含有量が１４重量％を超えると他の水素吸蔵作用を有する相の割合が低下し、水素吸蔵量そのものが低下して放電容量が小さくなるおそれがある。
さらに、本発明の水素吸蔵合金においては、該ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相が、４〜７重量％含まれていることがより好ましく、これによって高い放電容量を維持しつつ、レート特性も特に優れたものとなる。
In the hydrogen storage alloy of the present invention, the TiNi 3 phase or Ti (NiCo) 3 phase, it is preferably contained in the range of 4-14 wt%. If the content of the TiNi 3 phase or Ti (NiCo) 3 phase is less than 4% by weight, the catalytic action in the hydrogen releasing reaction may not be sufficiently exhibited, and the improvement of the discharge characteristics may be insufficient, When the content exceeds 14% by weight, the ratio of the other phases having a hydrogen storage function is decreased, and the hydrogen storage amount itself is decreased, which may reduce the discharge capacity.
Furthermore, in the hydrogen storage alloy of the present invention, it is more preferable that the TiNi 3 phase or Ti (NiCo) 3 phase is contained in an amount of 4 to 7% by weight, thereby maintaining rate characteristics while maintaining a high discharge capacity. Is also particularly excellent.
尚、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相の含有量は、電子線プローブマイクロアナリシス（ＥＰＭＡ）や、Ｘ線回折により分析した後、リートベルト法を用いた解析によって算出することができる。 The content of the TiNi 3 phase or Ti (NiCo) 3 phase can be calculated by analysis using the Rietveld method after analysis by electron probe microanalysis (EPMA) or X-ray diffraction.
また、本発明に係る水素吸蔵合金は、その化学組成が、下記一般式（１）で表されるものである。
Ｒ１vＴｉxＲ２yＲ３z （１）
ここで、ｖ、ｘ、ｙおよびｚは、０＜ｖ、１≦ｘ≦５、２≦ｙ≦４．５、７５≦ｚ≦８３であって、且つｖ＋ｘ＋ｙ＋ｚ＝１００を満たす数である。
ｘが１に満たなければＴｉＮｉ3相やＴｉ（ＮｉＣｏ）3相の生成量が減少し、触媒機能が十分に発揮されない虞があり、逆にｘが５を超えると水素吸蔵合金の容量が減少する虞がある。
The hydrogen storage alloy according to the present invention has a chemical composition represented by the following general formula (1).
R1 v Ti x R2 y R3 z (1)
Here, v, x, y, and z are numbers satisfying 0 <v, 1 ≦ x ≦ 5, 2 ≦ y ≦ 4.5, and 75 ≦ z ≦ 83, and satisfying v + x + y + z = 100.
If x is less than 1, the amount of TiNi 3 phase or Ti (NiCo) 3 phase is reduced and the catalytic function may not be fully exhibited. Conversely, if x exceeds 5, the capacity of the hydrogen storage alloy decreases. There is a risk of doing.
また、本発明に係る水素吸蔵合金は、前記式（１）におけるｖが、１３≦ｖ≦１６である化学組成が好ましい。ｖの値をこのような範囲とすれば、水素吸蔵合金の水素吸蔵容量を増大させることができる。
また、前記式（１）におけるｘが３≦ｘ≦４である化学組成が好ましい。ｘがこのような範囲であれば、該水素吸蔵合金からの水素の放出がより一層促進され、二次電池においては特に優れたレート特性を示すものとなる。
さらに、ｚが７５未満や、８３を超える場合には、ＰｕＮｉ3型の結晶構造を有する（Ｒ１aＴｉbＲ２c）Ｒ３3相の生成比率が低下し、水素吸蔵合金の容量が減少する虞がある。
Further, the hydrogen storage alloy according to the present invention preferably has a chemical composition in which v in the formula (1) is 13 ≦ v ≦ 16. If the value of v is in such a range, the hydrogen storage capacity of the hydrogen storage alloy can be increased.
Moreover, the chemical composition whose x in said Formula (1) is 3 <= x <= 4 is preferable. When x is in such a range, the release of hydrogen from the hydrogen storage alloy is further promoted, and in the secondary battery, particularly excellent rate characteristics are exhibited.
Further, when z is less than 75 or exceeds 83, the production ratio of the (R1 a Ti b R2 c ) R3 3 phase having a PuNi 3 type crystal structure is lowered, and the capacity of the hydrogen storage alloy may be reduced. There is.
また、前記式（１）において、Ｒ１は、Ｙを含む希土類元素から選ばれる１種又は２種以上の元素であり、例えば、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄなどが例示される。さらに、該Ｒ１としては、希土類元素の混合物であるミッシュメタル（Ｍｍ）が用いられてもよい。尚、ミッシュメタルとしては、Ｌａ、Ｃｅ、Ｐｒ及びＮｄの含有量が９９重量％以上の合金が望ましい。具体的には、Ｃｅ含有量が５０重量％以上で、Ｌａ含有量が３０重量％以下であるＣｅリッチなミッシュメタル（Ｍｍ）、Ｌａ含有量が前記Ｍｍに比べて多いＬａリッチなミッシュメタル（Ｌｍ）が挙げられる。
本発明においては、高容量化という観点から、Ｒ１として原子半径の大きなＬａ、若しくはＬａの含有割合の多いＭｍが好ましい。
In the formula (1), R1 is one or more elements selected from rare earth elements including Y. Examples thereof include Y, La, Ce, Pr, and Nd. Further, as R1, Misch metal (Mm) that is a mixture of rare earth elements may be used. As the misch metal, an alloy having a content of La, Ce, Pr and Nd of 99% by weight or more is desirable. Specifically, Ce-rich misch metal (Mm) having a Ce content of 50% by weight or more and a La content of 30% by weight or less, a La-rich misch metal having a La content higher than the Mm ( Lm).
In the present invention, from the viewpoint of increasing the capacity, R1 having a large atomic radius or Mm having a large La content is preferable.
また、前記式（１）において、Ｒ２は、アルカリ土類金属から選ばれる１種又は２種以上の元素であり、例えば、Ｂｅ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｒａなどが例示される。尚、本発明においては、ＢｅおよびＭｇもアルカリ土類金属に属するものとする。
本発明においては、ＰｕＮｉ3型の結晶構造を形成するという観点から、Ｒ２としてＭｇが好ましい。
Moreover, in said Formula (1), R2 is 1 type, or 2 or more types of elements chosen from alkaline-earth metal, for example, Be, Mg, Ca, Sr, Ba, Ra etc. are illustrated. In the present invention, Be and Mg also belong to alkaline earth metals.
In the present invention, Mg is preferable as R2 from the viewpoint of forming a PuNi 3 type crystal structure.
また、前記式（１）において、Ｒ３は、Ｎｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ、ＳｉおよびＡｌからなる群から選ばれる１種又は２種以上の元素である。
本発明においては、ＰｕＮｉ3型の結晶構造を有する（Ｒ１aＴｉbＲ２c）Ｒ３3相の生成を促進し、且つ水素吸蔵合金の容量を増大させるという観点から、Ｒ３としてＮｉを用いることが好ましい。
さらに、Ｒ３としてＡｌを含有することが好ましく、Ａｌを含有することにより、上記のＣａＣｕ5型結晶構造からなるＲ１Ｒ３5相、ＰｕＮｉ3型結晶構造からなる（Ｒ１aＴｉbＲ２c）Ｒ３3相およびＴｉＮｉ3型結晶相の全ての結晶相を比較的容易に生成させることができる。Ａｌの含有量は、該水素吸蔵合金の化学組成中、１〜３モル％が好ましく、２モル％が特に好ましい。
In the formula (1), R3 is one or more elements selected from the group consisting of Ni, Co, Mn, Fe, Cu, Cr, Si and Al.
In the present invention, Ni is used as R3 from the viewpoint of promoting the formation of the (R1 a Ti b R2 c ) R3 3 phase having a PuNi 3 type crystal structure and increasing the capacity of the hydrogen storage alloy. preferable.
Furthermore, it is preferable to contain Al as R3, and by containing Al, the R1R3 5 phase composed of the above-mentioned CaCu 5 type crystal structure and the (R1 a Ti b R2 c ) R3 3 phase composed of the PuNi 3 type crystal structure And all the crystal phases of the TiNi 3 type crystal phase can be produced relatively easily. The content of Al is preferably 1 to 3 mol%, particularly preferably 2 mol%, in the chemical composition of the hydrogen storage alloy.
本発明に係る水素吸蔵合金の具体的な化学組成（モル比）としては、例えば、
Ｌａ13Ｔｉ4Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2、Ｌａ15Ｔｉ2Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2、Ｌａ16Ｔｉ1Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2などが挙げられる。
As a specific chemical composition (molar ratio) of the hydrogen storage alloy according to the present invention, for example,
Examples include La 13 Ti 4 Mg 4 Ni 69 Co 6 Al 2 Mn 2 , La 15 Ti 2 Mg 4 Ni 69 Co 6 Al 2 Mn 2 , and La 16 Ti 1 Mg 4 Ni 69 Co 6 Al 2 Mn 2 .
本発明に係る水素吸蔵合金は、ＰｕＮｉ3型結晶構造からなる（Ｒ１aＴｉbＲ２c）Ｒ３3相が、合金全体に対して２５〜７０重量％有するものが好ましく、４０〜７０％含有するものがより好ましい。 The hydrogen storage alloy according to the present invention is preferably such that the (R1 a Ti b R2 c ) R3 3 phase having a PuNi 3 type crystal structure has 25 to 70% by weight with respect to the whole alloy, and contains 40 to 70%. Those are more preferred.
斯かるＲ１Ｒ３5相としては、例えば、Ｌａ（ＮｉＣｏＭｎ）5相が挙げられ、また、（Ｒ１aＴｉbＲ２c）Ｒ３3相としては、（ＬａＴｉＭｇ）Ｎｉ3相が挙げられる。 Examples of such R1R3 5 phase include La (NiCoMn) 5 phase, and examples of (R1 a Ti b R2 c ) R3 3 phase include (LaTiMg) Ni 3 phase.
また、本発明に係る水素吸蔵合金は、前記ＰｕＮｉ3型結晶からなる（Ｒ１aＴｉbＲ２c）Ｒ３3相のａ軸長が、５．０１６〜５．０２５Åであることが好ましい。該ａ軸長が５．０１６〜５．０２５Åの範囲内であれば、高容量を維持しつつ高率放電特性（レート特性）の向上を図ることができる。
尚、ａ軸長は、Ｘ線回折パターンから算定することができる。
In the hydrogen storage alloy according to the present invention, it is preferable that the a-axis length of the (R1 a Ti b R2 c ) R3 3 phase made of the PuNi 3 type crystal is 5.016 to 5.025 mm. If the a-axis length is in the range of 5.016 to 5.025 mm, high rate discharge characteristics (rate characteristics) can be improved while maintaining high capacity.
The a-axis length can be calculated from the X-ray diffraction pattern.
また、本発明においては、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相からなる単結晶、前記Ｒ１Ｒ３5相からなる単結晶、前記（Ｒ１aＴｉbＲ２c）Ｒ３3相からなる単結晶（一次粒子）の径を１０〜１００ｎｍとすることが好ましい。このように、一次粒子の径を上記のような範囲とすることにより、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相と、前記Ｒ１Ｒ３5相や前記（Ｒ１aＴｉbＲ２c）Ｒ３3相との間の接触面積が大きくなり、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相の触媒としての機能が十分に発揮され、さらに放電の高効率化を図ることができる。
尚、一次粒子の径が１０〜１００ｎｍであるとは、一次粒子の略全てが最小１０ｎｍ、最大１００ｎｍの範囲内に含まれることを意味するものである。また、該一次粒子とは、１個の結晶子で構成された単結晶構造を有する粒子（結晶粒ともいう）のことをいう。
結晶粒径は、透過型電子顕微鏡（Ｈｉｔａｃｈｉ Ｈ９０００）を用い、任意の１００個を対象としてそれぞれの結晶粒の最も長い長辺と最も短い短辺の長さを測定し、下記の式により求めた。
結晶粒径＝（長辺＋短辺）／２
In the present invention, a single crystal composed of the TiNi 3 phase or Ti (NiCo) 3 phase, a single crystal composed of the R1R3 5 phase, a single crystal composed of the (R1 a Ti b R2 c ) R3 3 phase (primary The diameter of the particles is preferably 10 to 100 nm. Thus, by setting the diameter of the primary particles in the above range, the TiNi 3 phase or Ti (NiCo) 3 phase, the R1R3 5 phase, the (R1 a Ti b R2 c ) R3 3 phase, The contact area between the two is increased, the function of the TiNi 3 phase or Ti (NiCo) 3 phase catalyst is sufficiently exerted, and the discharge efficiency can be further increased.
The primary particle diameter of 10 to 100 nm means that almost all of the primary particles are included in the range of a minimum of 10 nm and a maximum of 100 nm. The primary particles are particles having a single crystal structure (also referred to as crystal grains) composed of one crystallite.
The crystal grain size was determined by the following formula using a transmission electron microscope (Hitachi H9000), measuring the length of the longest and shortest short sides of each crystal grain for any 100 samples. .
Crystal grain size = (long side + short side) / 2
さらに、前記Ｒ１Ｒ３5相や前記（Ｒ１aＴｉbＲ２c）Ｒ３3相は、水素を吸蔵および放出する際に一次粒子の大きさが変化するが、変化の度合いが両相で異なる。これに対して、前記ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相は、水素を吸蔵および放出することがなく、一次粒子の大きさが変わらないものと考えられる。本発明は、上記の如く、一次粒子の大きさを１０〜１００ｎｍとすることにより、一次粒子の体積変化が生じた際に、該一次粒子の粒界に生じる歪みの大きさを低減することができ、粒界における亀裂を抑制して耐久性に優れた水素吸蔵合金を構成することができる。
なお、このような微小な一次粒子の集合体からなる水素吸蔵合金は、溶融させた材料を急冷固化し、その後、後述する条件下において焼鈍することによって得ることができる。
Further, in the R1R3 5 phase and the (R1 a Ti b R2 c ) R3 3 phase, the size of the primary particles changes when storing and releasing hydrogen, but the degree of change differs between the two phases. On the other hand, the TiNi 3 phase or Ti (NiCo) 3 phase does not occlude and release hydrogen, and the primary particle size is considered not to change. In the present invention, as described above, by setting the size of the primary particles to 10 to 100 nm, when the volume change of the primary particles occurs, it is possible to reduce the size of distortion generated at the grain boundaries of the primary particles. It is possible to form a hydrogen storage alloy having excellent durability by suppressing cracks at grain boundaries.
In addition, the hydrogen storage alloy which consists of an aggregate | assembly of such a micro primary particle can be obtained by rapidly solidifying the melted material and then annealing it on the conditions mentioned later.
次に、本発明の水素吸蔵合金の製造方法について説明する。
まず、目的とする水素吸蔵合金の化学組成に基づいて原料粉末を所定量秤量し、反応容器に入れ、不活性ガス雰囲気中で高周波溶融炉を用いて該原料粉末を溶融させる。そして、溶融状態から毎秒１０００Ｋ／秒以上の冷却速度で急冷凝固させることにより溶製する。これによって、目的とする合金相を効率的に生成させることができる。
さらに、目的の合金相の生成割合を増やすために、加圧状態のＡｒやＨｅなどの不活性ガス雰囲気中で焼鈍を行なうことが好ましい。焼鈍条件は、５５０〜１１００℃の温度範囲にて２〜５０時間、より好ましくは８００〜１０００℃の温度範囲にて２〜１０時間、さらに好ましくは９００〜１０００℃の温度範囲にて３〜８時間とすることが好ましい。また、焼鈍の際の不活性ガスとしてはヘリウムガスを用いることが好ましく、加圧条件としては、０．１ＭＰａ（ゲージ圧）以上とすることが好ましく、０．２〜０．５ＭＰａ（ゲージ圧）とすることがより好ましい。
Next, the manufacturing method of the hydrogen storage alloy of this invention is demonstrated.
First, a predetermined amount of raw material powder is weighed based on the chemical composition of the target hydrogen storage alloy, put in a reaction vessel, and melted in an inert gas atmosphere using a high-frequency melting furnace. And it melts by making it rapidly solidify at a cooling rate of 1000 K / second or more from the molten state. Thereby, the target alloy phase can be efficiently generated.
Furthermore, in order to increase the production rate of the target alloy phase, it is preferable to perform annealing in an inert gas atmosphere such as Ar or He under pressure. The annealing conditions are 2 to 50 hours in the temperature range of 550 to 1100 ° C, more preferably 2 to 10 hours in the temperature range of 800 to 1000 ° C, and even more preferably 3 to 8 in the temperature range of 900 to 1000 ° C. Time is preferred. Moreover, it is preferable to use helium gas as an inert gas at the time of annealing, and as pressurization conditions, it is preferable to be 0.1 MPa (gauge pressure) or more, and 0.2 to 0.5 MPa (gauge pressure). More preferably.
本発明の水素吸蔵合金を電極として使用する際には、水素吸蔵合金を粉砕して使用することが好ましい。粉砕は、焼鈍の前後どちらで行ってもよいが、粉砕により表面積が大きくなるため、合金表面の酸化を防止する観点から、焼鈍後に粉砕するのが望ましい。粉砕は、合金表面の酸化防止のために不活性雰囲気中で行うことが好ましい。前記粉砕は、例えば、ボールミルなどが用いられる。 When the hydrogen storage alloy of the present invention is used as an electrode, the hydrogen storage alloy is preferably used after being pulverized. The pulverization may be performed either before or after annealing, but since the surface area is increased by pulverization, it is desirable to pulverize after annealing from the viewpoint of preventing oxidation of the alloy surface. The pulverization is preferably performed in an inert atmosphere to prevent oxidation of the alloy surface. For the pulverization, for example, a ball mill or the like is used.
必要により粉末化した後、得られた粉末を適当なバインダー（例えば、ポリビニルアルコール等の樹脂）および水（または他の液体）と混合してペースト状とし、ニッケル多孔体に充填して乾燥した後、所望の電極形状に加圧成型することにより、ニッケル−水素電池等の二次電池に使用しうる負極を製造することができる。 After powdering if necessary, the obtained powder is mixed with an appropriate binder (for example, a resin such as polyvinyl alcohol) and water (or other liquid) to form a paste, filled into a nickel porous body and dried Then, a negative electrode that can be used for a secondary battery such as a nickel-hydrogen battery can be manufactured by pressure molding into a desired electrode shape.
前記のようにして作製された負極は、正極（例えばニッケル電極 ）、およびアルカリ電解液等と組合わされ二次電池（例えば、ニッケル−水素電池）が製造される。 The negative electrode produced as described above is combined with a positive electrode (for example, a nickel electrode) and an alkaline electrolyte to produce a secondary battery (for example, a nickel-hydrogen battery).
以下、実施例および比較例を用いて本発明を更に具体的に説明するが、本発明は、以下の実施例に限定されるものではない。なお、各種特性については以下の方法によって測定を行った。 Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Various characteristics were measured by the following methods.
（実施例１）
水素吸蔵合金の元素のモル比がＬａ１３、Ｔｉ４、Ｍｇ４、Ｎｉ６９、Ｃｏ６、Ａｌ２およびＭｎ２となるように原料インゴットをそれぞれ所定量秤量し、るつぼに入れ、アルゴンガス雰囲気下において、高周波溶融炉を用いて１５００℃に加熱し、材料を溶融させた。さらに、溶融された材料を前記高周波溶融炉中で水冷鋳型に移すことによって冷却（徐冷）し、固化させることにより化学組成がＬａ13Ｔｉ4Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2で表されるＴｉＮｉ3相含有水素吸蔵合金を得た。尚、合金の化学組成はＩＣＰ分析により測定した。
得られた水素吸蔵合金を、アルゴン雰囲気下で粉砕機により機械的に粉砕し、平均粒径（Ｄ５０）が６０μｍとなるように調整した。
尚、水素吸蔵合金の平均粒径及び粒度分布は、粒度分析計（マイクロトラック社製、品番「ＭＴ３０００」）を用い、レーザ回折・散乱法で測定し、粉体の全体積を１００％とした際の累積カーブが５０％となる点の粒径、即ち、累積平均径Ｄ５０を平均粒径とした。
Example 1
Each raw material ingot was weighed in a predetermined amount so that the molar ratio of the elements of the hydrogen storage alloy was La13, Ti4, Mg4, Ni69, Co6, Al2 and Mn2, placed in a crucible, and then used in a high-frequency melting furnace in an argon gas atmosphere. And heated to 1500 ° C. to melt the material. Further, the molten material is cooled (slowly cooled) by transferring it to a water-cooled mold in the high-frequency melting furnace, and solidified by being solidified, whereby the chemical composition is expressed as La 13 Ti 4 Mg 4 Ni 69 Co 6 Al 2 Mn 2. A TiNi 3 phase-containing hydrogen storage alloy was obtained. The chemical composition of the alloy was measured by ICP analysis.
The obtained hydrogen storage alloy was mechanically pulverized by a pulverizer under an argon atmosphere, and the average particle diameter (D50) was adjusted to 60 μm.
The average particle size and particle size distribution of the hydrogen storage alloy were measured by a laser diffraction / scattering method using a particle size analyzer (manufactured by Microtrack, product number “MT3000”), and the total volume of the powder was 100%. The particle diameter at which the cumulative curve at that time becomes 50%, that is, the cumulative average diameter D50 was taken as the average particle diameter.
（実施例２）
実施例１と同様にしてＴｉＮｉ3相含有水素吸蔵合金を作成し、さらに、０．２ＭＰａに加圧されたアルゴンガス雰囲気下、電気炉を用いて９１０℃の温度で７時間の熱処理を行い、焼鈍を行なった。そして、得られた水素吸蔵合金をアルゴン雰囲気下で粉砕機により機械的に粉砕し、平均粒径（Ｄ５０）が６０μｍとなるように調整した。
(Example 2)
A TiNi 3 phase-containing hydrogen storage alloy was prepared in the same manner as in Example 1, and further heat-treated at a temperature of 910 ° C. for 7 hours using an electric furnace under an argon gas atmosphere pressurized to 0.2 MPa, Annealing was performed. The obtained hydrogen storage alloy was mechanically pulverized by a pulverizer under an argon atmosphere, and the average particle size (D50) was adjusted to 60 μm.
（実施例３）
電気炉を用いて９４０℃の温度で７時間の熱処理を行う以外は、実施例２と同様にして水素吸蔵合金の粉末を得た。
(Example 3)
A hydrogen storage alloy powder was obtained in the same manner as in Example 2 except that heat treatment was performed at a temperature of 940 ° C. for 7 hours using an electric furnace.
（実施例４）
電気炉を用いて９７０℃の温度で７時間の熱処理を行う以外は、実施例２と同様にして水素吸蔵合金の粉末を得た。
Example 4
A hydrogen storage alloy powder was obtained in the same manner as in Example 2 except that heat treatment was performed at 970 ° C. for 7 hours using an electric furnace.
（実施例５）
電気炉を用いて１０００℃の温度で７時間の熱処理を行う以外は、実施例２と同様にして水素吸蔵合金の粉末を得た。
(Example 5)
A hydrogen storage alloy powder was obtained in the same manner as in Example 2 except that heat treatment was performed at 1000 ° C. for 7 hours using an electric furnace.
（比較例１）
水素吸蔵合金の元素のモル比がＬａ１３、Ｃｅ２、Ｎｄ１、Ｎｉ６１、Ｃｏ１３、Ｍｎ５及びＡｌ５となるように原料インゴットをそれぞれ所定量秤量し、るつぼに入れ、アルゴンガス雰囲気下において、高周波溶融炉を用いて１５００℃に加熱し、材料を溶融させた。さらに、溶融された材料を前記高周波溶融炉中で水冷鋳型に移すことによって徐冷し、固化させることにより化学組成がＬａ13Ｃｅ2Ｎｄ1Ｎｉ61Ｃｏ13Ｍｎ5Ａｌ5である水素吸蔵合金を得た。
(Comparative Example 1)
Each raw material ingot was weighed in a predetermined amount so that the molar ratio of the elements of the hydrogen storage alloy was La13, Ce2, Nd1, Ni61, Co13, Mn5, and Al5, placed in a crucible, and used in a high-frequency melting furnace in an argon gas atmosphere. And heated to 1500 ° C. to melt the material. Furthermore, a hydrogen storage alloy having a chemical composition of La 13 Ce 2 Nd 1 Ni 61 Co 13 Mn 5 Al 5 is obtained by slow cooling and solidifying the molten material by transferring it to a water-cooled mold in the high-frequency melting furnace. Obtained.
次に、０．２ＭＰａに加圧されたアルゴンガス雰囲気下、電気炉を用いて１０００℃の温度で７時間の熱処理を行い、再結晶化および焼鈍を行なった。そして、得られた水素吸蔵合金を、アルゴン雰囲気下で粉砕機により機械的に粉砕し、平均粒径（Ｄ５０）が６０μｍとなるように調整した。 Next, heat treatment was performed for 7 hours at a temperature of 1000 ° C. using an electric furnace in an argon gas atmosphere pressurized to 0.2 MPa, and recrystallization and annealing were performed. The obtained hydrogen storage alloy was mechanically pulverized by a pulverizer under an argon atmosphere, and the average particle diameter (D50) was adjusted to 60 μm.
（比較例２）
水素吸蔵合金の元素のモル比をＬａ１７、Ｍｇ８、Ｎｉ６２及びＣｏ１３とすること以外は比較例１と同様にし、化学組成がＬａ17Ｍｇ8Ｎｉ62Ｃｏ13である水素吸蔵合金を得た。さらに、熱処理温度を９００℃とする以外は比較例１と同様にして平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Comparative Example 2)
A hydrogen storage alloy having a chemical composition of La 17 Mg 8 Ni 62 Co 13 was obtained in the same manner as in Comparative Example 1 except that the molar ratio of elements of the hydrogen storage alloy was La17, Mg8, Ni62, and Co13. Further, a hydrogen storage alloy having an average particle size (D50) of 60 μm was obtained in the same manner as in Comparative Example 1 except that the heat treatment temperature was 900 ° C.
（比較例３）
水素吸蔵合金の元素のモル比をＬａ１５、Ｍｇ６、Ｎｉ６５、Ｃｏ６、Ａｌ４及びＭｎ４とすること以外は比較例１と同様にし、化学組成がＬａ15Ｍｇ6Ｎｉ65Ｃｏ6Ａｌ4Ｍｎ4である水素吸蔵合金を得た。さらに、熱処理温度を９８０℃とする以外は比較例１と同様にして平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Comparative Example 3)
Hydrogen whose chemical composition is La 15 Mg 6 Ni 65 Co 6 Al 4 Mn 4 , except that the molar ratio of the elements of the hydrogen storage alloy is La15, Mg6, Ni65, Co6, Al4, and Mn4. A storage alloy was obtained. Further, a hydrogen storage alloy having an average particle diameter (D50) of 60 μm was obtained in the same manner as in Comparative Example 1 except that the heat treatment temperature was 980 ° C.
（比較例４）
水素吸蔵合金の元素のモル比をＬａ１５、Ｔｉ２、Ｍｇ４、Ｎｉ７２、Ｃｏ４及びＭｎ３とすること以外は比較例１と同様にし、化学組成がＬａ15Ｔｉ2Ｍｇ4Ｎｉ72Ｃｏ4Ｍｎ3である水素吸蔵合金を得た。さらに、熱処理温度を９４０℃とする以外は比較例１と同様にして平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Comparative Example 4)
Hydrogen whose chemical composition is La 15 Ti 2 Mg 4 Ni 72 Co 4 Mn 3 , except that the molar ratio of the elements of the hydrogen storage alloy is La15, Ti2, Mg4, Ni72, Co4, and Mn3. A storage alloy was obtained. Further, a hydrogen storage alloy having an average particle diameter (D50) of 60 μm was obtained in the same manner as in Comparative Example 1 except that the heat treatment temperature was 940 ° C.
（実施例６）
実施例１と同じモル比となるように原料インゴットをそれぞれ所定量秤量し、るつぼに入れ、アルゴンガス雰囲気下において、高周波溶融炉を用いて１５００℃に加熱し、材料を溶融させた。さらに、溶融状態にある材料を回転冷却ロールに噴射することによって１００，０００Ｋ／秒以上の冷却速度で冷却（急冷）して固化させ、実施例１と同じ化学組成で表されるＴｉＮｉ3相含有水素吸蔵合金を得た。
得られた水素吸蔵合金を、０．３ＭＰａに加圧されたアルゴンガス雰囲気下、電気炉を用いて９４０℃の温度で７時間の熱処理を行い、再結晶化および焼鈍を行なった。
さらに、得られた水素吸蔵合金をアルゴン雰囲気下で粉砕機により機械的に粉砕し、平均粒径（Ｄ５０）が６０μｍとなるように調整した。
(Example 6)
A predetermined amount of each raw material ingot was weighed so as to have the same molar ratio as in Example 1, placed in a crucible, and heated to 1500 ° C. using an induction melting furnace in an argon gas atmosphere to melt the material. Furthermore, the material in a molten state is cooled (rapidly cooled) at a cooling rate of 100,000 K / second or more by injecting the material into a rotating cooling roll, and solidified, and includes a TiNi 3 phase represented by the same chemical composition as in Example 1. A hydrogen storage alloy was obtained.
The obtained hydrogen storage alloy was subjected to heat treatment for 7 hours at 940 ° C. using an electric furnace in an argon gas atmosphere pressurized to 0.3 MPa to perform recrystallization and annealing.
Furthermore, the obtained hydrogen storage alloy was mechanically pulverized by a pulverizer under an argon atmosphere, and the average particle diameter (D50) was adjusted to 60 μm.
（実施例７）
水素吸蔵合金の元素のモル比をＬａ１５、Ｔｉ２、Ｍｇ４、Ｎｉ６９、Ｃｏ６、Ａｌ２及びＭｎ２とすること以外は実施例６と同様にし、化学組成がＬａ15Ｔｉ2Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Example 7)
The chemical composition is La 15 Ti 2 Mg 4 Ni 69 Co 6 Al 2 Mn, except that the molar ratio of the elements of the hydrogen storage alloy is La15, Ti2, Mg4, Ni69, Co6, Al2 and Mn2. A hydrogen storage alloy of 2 was obtained. Furthermore, it grind | pulverized like Example 6 and obtained the hydrogen storage alloy whose average particle diameter (D50) is 60 micrometers.
（実施例８）
水素吸蔵合金の元素のモル比をＬａ１６、Ｔｉ１、Ｍｇ４、Ｎｉ６９、Ｃｏ６、Ａｌ２及びＭｎ２とすること以外は実施例６と同様にし、化学組成がＬａ15Ｔｉ2Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Example 8)
The chemical composition is La 15 Ti 2 Mg 4 Ni 69 Co 6 Al 2 Mn, except that the molar ratio of the elements of the hydrogen storage alloy is La16, Ti1, Mg4, Ni69, Co6, Al2 and Mn2. A hydrogen storage alloy of 2 was obtained. Furthermore, it grind | pulverized like Example 6 and obtained the hydrogen storage alloy whose average particle diameter (D50) is 60 micrometers.
（実施例９）
実施例６と同様にして化学組成がＬａ15Ｔｉ2Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、０．５ＭＰａに加圧されたアルゴンガス雰囲気下とする以外は、実施例６と同様にして熱処理を行い、その後、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
Example 9
In the same manner as in Example 6, a hydrogen storage alloy having a chemical composition of La 15 Ti 2 Mg 4 Ni 69 Co 6 Al 2 Mn 2 was obtained. Further, heat treatment was performed in the same manner as in Example 6 except that the atmosphere was an argon gas atmosphere pressurized to 0.5 MPa, and then pulverized in the same manner as in Example 6 to obtain an average particle diameter (D50) of 60 μm. A hydrogen storage alloy was obtained.
（実施例１０）
溶融された材料を高周波溶融炉中で水冷鋳型に移して徐冷すること以外は実施例６と同様にして化学組成がＬａ15Ｔｉ2Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同条件にて熱処理を行い、その後、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Example 10)
A hydrogen storage alloy having a chemical composition of La 15 Ti 2 Mg 4 Ni 69 Co 6 Al 2 Mn 2 as in Example 6 except that the molten material is transferred to a water-cooled mold in a high-frequency melting furnace and gradually cooled. Got. Further, heat treatment was performed under the same conditions as in Example 6, and then pulverized in the same manner as in Example 6 to obtain a hydrogen storage alloy having an average particle size (D50) of 60 μm.
（実施例１１）
水素吸蔵合金の元素のモル比をＬａ１３、Ｔｉ４、Ｍｇ４、Ｎｉ６９、Ｆｅ３、Ｃｕ３、Ａｌ２及びＭｎ２とすること以外は実施例６と同様にし、化学組成がＬａ13Ｔｉ4Ｍｇ4Ｎｉ69Ｆｅ3Ｃｕ3Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Example 11)
The chemical composition is La 13 Ti 4 Mg 4 Ni 69 Fe 3 Cu except that the molar ratio of the elements of the hydrogen storage alloy is La13, Ti4, Mg4, Ni69, Fe3, Cu3, Al2 and Mn2. A hydrogen storage alloy of 3 Al 2 Mn 2 was obtained. Furthermore, it grind | pulverized like Example 6 and obtained the hydrogen storage alloy whose average particle diameter (D50) is 60 micrometers.
（実施例１２）
水素吸蔵合金の元素のモル比をＭｍ１３、Ｔｉ４、Ｍｇ４、Ｎｉ７０、Ｃｏ４、Ｓｉ１、Ａｌ２及びＭｎ２とすること以外は実施例６と同様にし、化学組成がＭｍ13Ｔｉ4Ｍｇ4Ｎｉ70Ｃｏ4Ｓｉ1Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。尚、Ｍｍ（ミッシュメタル）としては、Ｌａ８０％、Ｃｅ１％、Ｐｒ８％、Ｎｄ１１％を使用した。
(Example 12)
The chemical composition is Mm 13 Ti 4 Mg 4 Ni 70 Co 4 Si except that the molar ratio of the elements of the hydrogen storage alloy is Mm13, Ti4, Mg4, Ni70, Co4, Si1, Al2 and Mn2. A hydrogen storage alloy of 1 Al 2 Mn 2 was obtained. Furthermore, it grind | pulverized like Example 6 and obtained the hydrogen storage alloy whose average particle diameter (D50) is 60 micrometers. As Mm (Misch metal), La 80%, Ce 1%, Pr 8%, and Nd 11% were used.
（実施例１３）
水素吸蔵合金の元素のモル比をＬａ１４、Ｔｉ４、Ｍｇ４、Ｎｉ６８、Ｃｏ６、Ａｌ２及びＭｎ２とすること以外は実施例６と同様にし、化学組成がＬａ14Ｔｉ4Ｍｇ4Ｎｉ68Ｃｏ6Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Example 13)
The chemical composition is La 14 Ti 4 Mg 4 Ni 68 Co 6 Al 2 Mn, except that the molar ratio of the elements of the hydrogen storage alloy is La14, Ti4, Mg4, Ni68, Co6, Al2 and Mn2. A hydrogen storage alloy of 2 was obtained. Furthermore, it grind | pulverized like Example 6 and obtained the hydrogen storage alloy whose average particle diameter (D50) is 60 micrometers.
（実施例１４）
水素吸蔵合金の元素のモル比をＬａ１２、Ｔｉ４、Ｍｇ４、Ｎｉ７０、Ｃｏ６、Ａｌ２及びＭｎ２とすること以外は実施例６と同様にし、化学組成がＬａ12Ｔｉ4Ｍｇ4Ｎｉ70Ｃｏ6Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
（比較例５）
水素吸蔵合金の元素のモル比をＬａ１１、Ｔｉ６、Ｍｇ４、Ｎｉ６９、Ｃｏ６、Ａｌ２及びＭｎ２とすること以外は実施例６と同様にし、化学組成がＬａ11Ｔｉ6Ｍｇ4Ｎｉ69Ｃｏ6Ａｌ2Ｍｎ2である水素吸蔵合金を得た。さらに、実施例６と同様に粉砕して平均粒径（Ｄ５０）が６０μｍの水素吸蔵合金を得た。
(Example 14)
The chemical composition is La 12 Ti 4 Mg 4 Ni 70 Co 6 Al 2 Mn, except that the molar ratio of the elements of the hydrogen storage alloy is La12, Ti4, Mg4, Ni70, Co6, Al2 and Mn2. A hydrogen storage alloy of 2 was obtained. Furthermore, it grind | pulverized like Example 6 and obtained the hydrogen storage alloy whose average particle diameter (D50) is 60 micrometers.
(Comparative Example 5)
The chemical composition is La 11 Ti 6 Mg 4 Ni 69 Co 6 Al 2 Mn as in Example 6 except that the molar ratio of the elements of the hydrogen storage alloy is La11, Ti6, Mg4, Ni69, Co6, Al2 and Mn2. A hydrogen storage alloy of 2 was obtained. Furthermore, it grind | pulverized like Example 6 and obtained the hydrogen storage alloy whose average particle diameter (D50) is 60 micrometers.
（結晶構造の測定）
得られた粉末を、Ｘ線回折装置（ＢｒｕｋｅｒＡＸＳ社製、品番Ｍ０６ＸＣＥ）を用い、４０ｋＶ，１００ｍＡ（Ｃｕ管球）の条件でＸ線回折測定した後、得られたＸ線回折結果に基づいてリートベルト法（解析ソフト、ＲＩＥＴＡＮ２０００使用）により構造解析を行なった。各合金における生成相の含有量を表１に示す。
(Measurement of crystal structure)
The obtained powder was subjected to X-ray diffraction measurement under the conditions of 40 kV, 100 mA (Cu tube) using an X-ray diffractometer (manufactured by Bruker AXS, product number M06XCE), and then read based on the obtained X-ray diffraction result. Structural analysis was performed by the belt method (analysis software, using RIETA 2000). Table 1 shows the content of the product phase in each alloy.
（充放電特性の測定）
（ａ）電極の作製
得られた実施例又は比較例の水素吸蔵合金粉末１００重量部に、ニッケル粉末（ＩＮＣＯ社製、＃２１０）３重量部を加えて混合した後、増粘剤（メチルセルロース）を溶解した水溶液を加え、さらに、結着剤（スチレンブタジエンゴム）を１．５重量部加え、ペースト状にしたものを厚み４５μｍの穿孔鋼板（開口率６０％）の両面に塗布して乾燥した後、厚さ０．３６ｍｍにプレスし、負極とした。一方、正極としては、容量過剰のシンター式水酸化ニッケル電極を用いた。
(Measurement of charge / discharge characteristics)
(A) Preparation of electrode After adding and mixing 3 parts by weight of nickel powder (INCO, # 210) to 100 parts by weight of the obtained hydrogen storage alloy powder of Example or Comparative Example, thickener (methylcellulose) In addition, 1.5 parts by weight of a binder (styrene butadiene rubber) was added, and the paste was applied to both sides of a 45 μm-thick perforated steel sheet (opening ratio 60%) and dried. Thereafter, it was pressed to a thickness of 0.36 mm to obtain a negative electrode. On the other hand, as the positive electrode, an excess capacity sintered nickel hydroxide electrode was used.
（ｂ）開放形電池の作製
上述のようにして作製した負極をセパレータを介して正極で挟み込み、これらの電極に１０ｋｇｆ／ｃｍ2の圧力がかかるようにボルトで固定し、開放形セルに組み立てた。電解液としては、６．８ｍｏｌ／ＬのＫＯＨ溶液および０．８ｍｏｌ／ＬのＬｉＯＨ溶液からなる混合液を使用した。
(B) Production of an open-type battery The negative electrode produced as described above was sandwiched between positive electrodes through a separator, and these electrodes were fixed with bolts so that a pressure of 10 kgf / cm 2 was applied, and assembled into an open-type cell. . As the electrolytic solution, a mixed solution composed of a 6.8 mol / L KOH solution and a 0.8 mol / L LiOH solution was used.
（ｃ）０．２ItAにおける放電容量の測定
作製した電池を２０℃の水槽中に入れ、充電は０．１Ｃで１５０％、放電は０．２ＩｔＡで終止電圧−０．６Ｖ（ｖｓ．Ｈｇ／ＨｇＯ）となる条件で充放電を１０サイクル繰り返し、１０サイクル目の放電容量を測定して０．２ItAの放電容量[mAh／g]とした。
(C) Measurement of discharge capacity at 0.2 ItA The prepared battery was placed in a 20 ° C. water tank, charged at 150 ° C. at 0.1 C, discharged at 0.2 ItA, and final voltage −0.6 V (vs. Hg / HgO). The charge / discharge was repeated 10 cycles under the conditions of 2), and the discharge capacity at the 10th cycle was measured to obtain a discharge capacity [mAh / g] of 0.2 ItA.
（ｄ）レート特性の測定
前記０．２ItAの放電容量の測定に引き続き、同じ水槽中において、充電は０．１Ｃで１５０％、放電は３．０ＩｔＡで終止電圧−０．６Ｖ（ｖｓ．Ｈｇ／ＨｇＯ）となる条件で充放電を行い（即ち、１１サイクル目）、その際の放電容量を測定して３．０ItAの放電容量とし、放電レート（即ち、前記０．２ItA放電容量に対する３．０ItA放電容量の比）を求めた。結果をそれぞれ表３に示す。
(D) Measurement of rate characteristics Following measurement of the discharge capacity of 0.2 ItA, in the same water tank, charging was 150% at 0.1 C, discharging was 3.0 ItA, and final voltage was -0.6 V (vs. Hg / HgO) is charged / discharged (that is, the 11th cycle), the discharge capacity at that time is measured to obtain a discharge capacity of 3.0 ItA, and the discharge rate (that is, 3.0 ItA relative to the 0.2 ItA discharge capacity). The ratio of discharge capacity) was determined. The results are shown in Table 3, respectively.
表３に示したように、本発明に係る水素吸蔵合金（実施例１〜５）を用いた場合には、従来の比較例１や比較例２などの水素吸蔵合金を用いた場合に比べ、放電電流を大きくした場合でも放電電流が低下しにくく、二次電池のレート特性が顕著に改善されていることが認められる。
しかも、最大放電容量についても従来の比較例１や比較例２などの水素吸蔵合金と同程度の値が得られており、従って、本発明によれば最大放電容量を低下させることなくレート特性が顕著に改善された水素吸蔵合金が得られていることがわかる。
As shown in Table 3, when the hydrogen storage alloys according to the present invention (Examples 1 to 5) were used, compared to the case of using conventional hydrogen storage alloys such as Comparative Example 1 and Comparative Example 2, It can be seen that even when the discharge current is increased, the discharge current is unlikely to decrease, and the rate characteristics of the secondary battery are remarkably improved.
Moreover, the maximum discharge capacity is similar to that of the conventional hydrogen storage alloys such as Comparative Example 1 and Comparative Example 2. Therefore, according to the present invention, the rate characteristics can be obtained without reducing the maximum discharge capacity. It can be seen that a significantly improved hydrogen storage alloy is obtained.
また、実施例６〜１４の水素吸蔵合金では、実施例１〜５の水素吸蔵合金よりもさらに放電容量が高くなっていることが認められる。また、該実施例６〜９のうちでも、特にＴｉＮｉ3相を６％含む実施例６、実施例９、実施例１１〜１４の水素吸蔵合金は、高い放電容量に加えて８６〜９０％という極めて優れたレート特性を備えていることが認められる。さらに、該実施例６と９とを対比すると、０．５ＭＰａの圧力下において熱処理された実施例９の方が、より一層高い放電容量を達成していることが認められる。 Moreover, in the hydrogen storage alloy of Examples 6-14, it is recognized that the discharge capacity is still higher than the hydrogen storage alloy of Examples 1-5. Among Examples 6 to 9, the hydrogen storage alloys of Examples 6, 9 and 11 to 14 containing 6% of TiNi 3 phase are 86 to 90% in addition to high discharge capacity. It can be seen that it has very good rate characteristics. Further, comparing Examples 6 and 9, it can be seen that Example 9 that was heat-treated at a pressure of 0.5 MPa achieved a higher discharge capacity.
Claims (6)
ＴｉＮｉ3相又はＴｉ（ＮｉＣｏ）3相を有し、且つ、
ＣａＣｕ5型結晶構造からなるＲ１Ｒ３5相（但し、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ、ＳｉおよびＡｌからなる群から選択される１種又は２種以上の元素である）、
およびＰｕＮｉ3型結晶構造からなる（Ｒ１aＴｉbＲ２c）Ｒ３3相（但し、ａ＞０、ｂ＞０、ｃ＞０、ａ＋ｂ＋ｃ＝１であり、Ｒ１はＹを含む希土類元素から選択される１種又は２種以上の元素であり、Ｒ２はアルカリ土類金属から選択される１種又は２種以上の元素であり、Ｒ３はＮｉ、Ｃｏ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ、ＳｉおよびＡｌからなる群から選択される１種又は２種以上の元素である）
を有することを特徴とする水素吸蔵合金。 The chemical composition is the general formula R1 v Ti x R2 y R3 z (where 0 <v, 1 ≦ x ≦ 5, 2 ≦ y ≦ 4.5, 75 ≦ z ≦ 83, v + x + y + z = 100, and R1 is Y R2 is one or more elements selected from alkaline earth metals, R3 is Ni, Co, Mn, Al, A hydrogen storage alloy represented by the following: one or more elements selected from the group consisting of Cu, Fe, Cr and Si,
Having a TiNi 3 phase or Ti (NiCo) 3 phase, and
R1R3 5 phase having a CaCu 5 type crystal structure (where R1 is one or more elements selected from rare earth elements including Y, and R3 is Ni, Co, Mn, Fe, Cu, Cr, Si) And one or more elements selected from the group consisting of Al)
And PuNi of 3 type crystal structure (R1 a Ti b R2 c) R3 3 -phase (where, a> 0, b> 0 , c> a 0, a + b + c = 1, R1 is selected from rare earth elements including Y R2 is one or more elements selected from alkaline earth metals, and R3 is Ni, Co, Mn, Fe, Cu, Cr, Si, and Al. Or one or more elements selected from the group consisting of
The hydrogen storage alloy characterized by having.
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| CN115449726A (en) * | 2022-08-31 | 2022-12-09 | 广东省科学院资源利用与稀土开发研究所 | Process annealing method of La-Mg-Ni hydrogen storage alloy |
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