JP6105389B2 - Alkaline storage battery - Google Patents
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- 238000003860 storage Methods 0.000 title claims description 114
- 239000001257 hydrogen Substances 0.000 claims description 88
- 229910052739 hydrogen Inorganic materials 0.000 claims description 88
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 86
- 229910045601 alloy Inorganic materials 0.000 claims description 72
- 239000000956 alloy Substances 0.000 claims description 72
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 56
- 239000013078 crystal Substances 0.000 claims description 55
- 229910052759 nickel Inorganic materials 0.000 claims description 30
- 239000003792 electrolyte Substances 0.000 claims description 8
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 claims description 8
- 238000000634 powder X-ray diffraction Methods 0.000 claims description 7
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 7
- 229910052772 Samarium Inorganic materials 0.000 claims description 6
- 229910052727 yttrium Inorganic materials 0.000 claims description 5
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 18
- 238000005259 measurement Methods 0.000 description 17
- 229910052987 metal hydride Inorganic materials 0.000 description 16
- -1 nickel metal hydride Chemical class 0.000 description 12
- 239000000203 mixture Substances 0.000 description 9
- 238000007789 sealing Methods 0.000 description 9
- 239000000758 substrate Substances 0.000 description 8
- 239000000843 powder Substances 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 5
- 230000015556 catabolic process Effects 0.000 description 5
- 238000006731 degradation reaction Methods 0.000 description 5
- 239000007774 positive electrode material Substances 0.000 description 5
- 241000156302 Porcine hemagglutinating encephalomyelitis virus Species 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 150000002815 nickel Chemical class 0.000 description 4
- 238000010298 pulverizing process Methods 0.000 description 4
- 230000001172 regenerating effect Effects 0.000 description 4
- 229910052779 Neodymium Inorganic materials 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- 229910021503 Cobalt(II) hydroxide Inorganic materials 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000002174 Styrene-butadiene Substances 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- ASKVAEGIVYSGNY-UHFFFAOYSA-L cobalt(ii) hydroxide Chemical compound [OH-].[OH-].[Co+2] ASKVAEGIVYSGNY-UHFFFAOYSA-L 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000010494 dissociation reaction Methods 0.000 description 2
- 230000005593 dissociations Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229920002725 thermoplastic elastomer Polymers 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000003232 water-soluble binding agent Substances 0.000 description 2
- 150000003746 yttrium Chemical class 0.000 description 2
- 150000003751 zinc Chemical class 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- ONDPHDOFVYQSGI-UHFFFAOYSA-N zinc nitrate Chemical compound [Zn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ONDPHDOFVYQSGI-UHFFFAOYSA-N 0.000 description 2
- NGDQQLAVJWUYSF-UHFFFAOYSA-N 4-methyl-2-phenyl-1,3-thiazole-5-sulfonyl chloride Chemical compound S1C(S(Cl)(=O)=O)=C(C)N=C1C1=CC=CC=C1 NGDQQLAVJWUYSF-UHFFFAOYSA-N 0.000 description 1
- 229910005813 NiMH Inorganic materials 0.000 description 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001868 cobalt Chemical class 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 239000004816 latex Substances 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- 229910000652 nickel hydride Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- XMVONEAAOPAGAO-UHFFFAOYSA-N sodium tungstate Chemical compound [Na+].[Na+].[O-][W]([O-])(=O)=O XMVONEAAOPAGAO-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
- DEXZEPDUSNRVTN-UHFFFAOYSA-K yttrium(3+);trihydroxide Chemical compound [OH-].[OH-].[OH-].[Y+3] DEXZEPDUSNRVTN-UHFFFAOYSA-K 0.000 description 1
- UGZADUVQMDAIAO-UHFFFAOYSA-L zinc hydroxide Chemical compound [OH-].[OH-].[Zn+2] UGZADUVQMDAIAO-UHFFFAOYSA-L 0.000 description 1
- 229910021511 zinc hydroxide Inorganic materials 0.000 description 1
- 229940007718 zinc hydroxide Drugs 0.000 description 1
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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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Description
本発明は、水素吸蔵合金負極を用いたアルカリ蓄電池に関する。 The present invention relates to an alkaline storage battery using a hydrogen storage alloy negative electrode.
ニッケル水素蓄電池等のアルカリ蓄電池では、正極の極板容量に対し、負極の極板容量が高くなるように設計されている。これは負極において、過充電時の水素発生を防止するための充電リザーブと、過放電時の酸素発生を防止するための放電リザーブを確保するためである。一方、充放電の繰り返しなどにより、電池内材料（正極・負極材料、その他の材料）が酸化されると放電リザーブが増加／充電リザーブが減少する。加えて負極合金の酸化劣化によっても充電リザーブは減少し、最終的に充電リザーブが枯渇すると、過充電時に負極から水素が発生し、ガス圧上昇にともなうリークによりセパレータが保持する電解液が枯渇して充放電ができなくなる。 An alkaline storage battery such as a nickel metal hydride storage battery is designed such that the electrode plate capacity of the negative electrode is higher than the electrode plate capacity of the positive electrode. This is to ensure a charge reserve for preventing hydrogen generation during overcharge and a discharge reserve for preventing oxygen generation during overdischarge in the negative electrode. On the other hand, when the material in the battery (positive electrode / negative electrode material, other materials) is oxidized due to repeated charge / discharge, etc., the discharge reserve increases / the charge reserve decreases. In addition, the charge reserve decreases due to the oxidative deterioration of the negative electrode alloy.If the charge reserve is eventually depleted, hydrogen is generated from the negative electrode during overcharge, and the electrolyte retained by the separator is depleted due to leakage due to the gas pressure increase. Charge / discharge is not possible.
放電リザーブ量の蓄積量制御のための水素吸蔵合金の高耐久化及び高容量化の観点から、Ａ２Ｂ７型結晶構造やＡ５Ｂ１９型結晶構造を有するＭｇ含有水素吸蔵合金が検討されている（下記特許文献１〜３参照）。Ａ２Ｂ７型結晶構造の水素吸蔵合金は、ＡＢ２型結晶構造とＡＢ５型結晶構造とが２層を周期として重なり合った例えばＣｅ２Ｎｉ７型の六方晶系（２Ｈ）の結晶構造のものが知られている。Ａ５Ｂ１９型結晶構造の水素吸蔵合金は、ＡＢ２型結晶構造とＡＢ５型結晶構造とが３層を周期として積み重なった例えばＣｅ２Ｃｏ１９型の三方晶系（３Ｒ）の結晶構造のものと、ＡＢ２型結晶構造とＡＢ５型結晶構造とが２層を周期として重なり合った例えばＰｒ５Ｃｏ１９型の六方晶系（２Ｈ）の結晶構造のものとが知られている。 Mg-containing hydrogen storage alloys having an A2B7 type crystal structure or an A5B19 type crystal structure have been studied from the viewpoint of increasing the durability and capacity of the hydrogen storage alloy for controlling the amount of stored discharge reserve (the following patent documents) 1-3). As the hydrogen storage alloy having the A2B7 type crystal structure, for example, a Ce 2 Ni 7 type hexagonal crystal (2H) crystal structure in which the AB2 type crystal structure and the AB5 type crystal structure overlap each other with a period of two layers is known. Yes. The hydrogen storage alloy having an A5B19 crystal structure includes, for example, a Ce 2 Co 19 type trigonal (3R) crystal structure in which an AB2 type crystal structure and an AB5 type crystal structure are stacked with a period of three layers, and an AB2 type For example, a Pr 5 Co 19 type hexagonal (2H) crystal structure in which the crystal structure and the AB5 type crystal structure overlap each other with a period of two layers is known.
Ａ２Ｂ７型結晶構造の水素吸蔵合金は、水素の吸蔵・放出のサイクル寿命特性を向上させることができるが、大電流放電特性（アシスト出力）が不十分であって、従来の範囲を超えた高出力用途としては満足いく特性が得られない。Ａ５Ｂ１９型結晶構造の水素吸蔵合金は、単位結晶格子当たりのニッケル比率を増加させることができ、水素分子の吸着及び水素原子への解離を促進する活性点を増加させることが可能となるが、金属原子間の隙間が小さくなって水素吸蔵圧が上昇する。そのため、Ａ５Ｂ１９型結晶構造の水素吸蔵合金を大電流の充放電用途に用いると、水素吸蔵合金の微粉化が加速されて耐久性が低下する。 The hydrogen storage alloy with A2B7 crystal structure can improve the cycle life characteristics of hydrogen storage / release, but the high current discharge characteristics (assist output) is insufficient and the high output exceeds the conventional range. Satisfactory characteristics cannot be obtained for use. The hydrogen storage alloy having the A5B19 type crystal structure can increase the nickel ratio per unit crystal lattice and increase the active sites that promote the adsorption of hydrogen molecules and the dissociation into hydrogen atoms. The gap between atoms becomes smaller and the hydrogen storage pressure rises. For this reason, when a hydrogen storage alloy having an A5B19 crystal structure is used for charging and discharging with a large current, pulverization of the hydrogen storage alloy is accelerated and durability is lowered.
なお、従来の水素吸蔵合金負極を用いたアルカリ蓄電池では、出力特性（水素吸蔵圧が高いと有利）と回生特性（水素吸蔵圧が低いと有利）の両立のため、４０℃、Ｈ／Ｍ＝０．５における水素吸蔵圧が０．０２０ＭＰａ以上、０．０５５ＭＰａ以下のものが多く用いられている。 In addition, in the alkaline storage battery using the conventional hydrogen storage alloy negative electrode, 40 ° C., H / M = for compatibility between output characteristics (advantageous when the hydrogen storage pressure is high) and regenerative characteristics (advantageous when the hydrogen storage pressure is low). A hydrogen storage pressure at 0.5 of 0.020 MPa or more and 0.055 MPa or less is often used.
水素吸蔵合金負極を用いたアルカリ蓄電池をハイブリッド自動車（ＨＥＶ、ＰＨＥＶ）や電気自動車（ＥＶ）等の電源として用いるには、出力特性や回生特性だけでなく、多数の電池を用いる必要上、コストダウンが求められている。近年、磁石用途で用いられるＮｄなどの希土類元素については、価格が高騰しており、その使用量削減が必要となり、比較的安価なＬａへの置換えが検討されている。しかし、水素吸蔵合金中のＬａの添加量を単純に増加させていくと、水素吸蔵圧が低下するため、水素吸蔵合金負極を用いたアルカリ蓄電池では出力特性の低下が顕著となる。 In order to use an alkaline storage battery using a hydrogen storage alloy negative electrode as a power source for a hybrid vehicle (HEV, PHEV), an electric vehicle (EV), etc., it is necessary to use not only output characteristics and regenerative characteristics, but also a large number of batteries. Is required. In recent years, the price of rare earth elements such as Nd used in magnet applications has risen and it is necessary to reduce the amount used, and replacement with relatively inexpensive La is being studied. However, when the addition amount of La in the hydrogen storage alloy is simply increased, the hydrogen storage pressure decreases, so that the output characteristics of the alkaline storage battery using the hydrogen storage alloy negative electrode are significantly reduced.
また、水素吸蔵合金負極を用いたアルカリ蓄電池をＨＥＶ、ＰＨＥＶやＥＶ用途に用いるには、低温での高率放電性（例えば−１０℃で５Ｉｔ以上の放電性）が求められるだけでなく、エンジンなどの付近で高温放置されるため、耐高温特性も要求される。 In addition, in order to use alkaline storage batteries using a hydrogen storage alloy negative electrode for HEV, PHEV and EV applications, not only high-rate discharge characteristics at low temperatures (for example, discharge characteristics of 5 It or more at −10 ° C.) are required. Therefore, high temperature resistance is also required.
本発明の一態様のアルカリ蓄電池は、
水素吸蔵合金を主成分とする水素吸蔵合金負極と、
水酸化ニッケルを主成分とするニッケル正極と、
セパレータとからなる電極群をアルカリ電解液とともに外装缶内に備えたアルカリ蓄電池であって、
前記水素吸蔵合金は、Ｌａを主要希土類元素とする一般式（ＬａｘＬｎｙ）１一ｚＭｇｚＮｉｔ−ｕＴｕ（Ｔ：Ａｌ、Ｃｏ、Ｍｎ、Ｚｎから選択され、ＬｎはＬａ以外の希土類元素及びＹから選択された少なくとも１種であり、ｘ>ｙ、０．０９≦ｚ≦０．１４、３．６５≦ｔ≦３．８０、０．０５≦ｕ≦０．２５）であって、六方晶系（２Ｈ）のＡ５Ｂ１９型結晶構造のものと、三方晶系（３Ｒ）のＡ５Ｂ１９型結晶構造のものと、Ａ２Ｂ７型結晶構造のものとを含み、
前記六方晶系（２Ｈ）のＡ５Ｂ１９型結晶構造のもののＣｕ−Ｋα線による粉末Ｘ線回折強度ピークは、前記三方晶系（３Ｒ）のＡ５Ｂ１９型結晶構造のもの及びＡ２Ｂ７型結晶構造のものよりも大きいものとされている。
The alkaline storage battery of one embodiment of the present invention is
A hydrogen storage alloy negative electrode mainly composed of a hydrogen storage alloy;
A nickel positive electrode mainly composed of nickel hydroxide;
An alkaline storage battery comprising an electrode group consisting of a separator and an alkaline electrolyte in an outer can,
The hydrogen storage alloy is selected from the general formula (La x Ln y ) 11 z Mg z Ni tu- Tu (T: Al, Co, Mn, Zn) in which La is a main rare earth element, and Ln is other than La X> y, 0.09 ≦ z ≦ 0.14, 3.65 ≦ t ≦ 3.80, 0.05 ≦ u ≦ 0.25) A hexagonal (2H) A5B19 crystal structure, a trigonal (3R) A5B19 crystal structure, and an A2B7 crystal structure,
The powder X-ray diffraction intensity peak by Cu-Kα ray of the hexagonal (2H) A5B19 crystal structure is higher than that of the trigonal (3R) A5B19 crystal structure and A2B7 crystal structure. It is supposed to be big.
本発明のアルカリ蓄電池によれば、負極の水素吸蔵合金中に安価なＬａを特定量で含み、かつ、特定の結晶構造のものを含むものとしたことにより、従来の水素吸蔵合金負極を用いたアルカリ蓄電池と比較して、安価でありながら、放電出力特性が向上し、また高温耐久性も同等以上となる。なお、水素吸蔵合金中のＬａ以外の希土類元素Ｌｎとしては、Ｓｍ、Ｇｄ、Ｙの少なくとも１種を主要成分として含むことが好ましい。 According to the alkaline storage battery of the present invention, the conventional hydrogen storage alloy negative electrode is used because the hydrogen storage alloy of the negative electrode contains inexpensive La in a specific amount and includes a specific crystal structure. Compared with alkaline storage batteries, while being inexpensive, the discharge output characteristics are improved, and the high-temperature durability is equal to or higher. The rare earth element Ln other than La in the hydrogen storage alloy preferably includes at least one of Sm, Gd, and Y as a main component.
以下、本発明を実施するための形態について，各種実験例により詳細に説明する。ただし、以下に示す各種実験例は、本発明の技術思想を理解するために例示するものであって、本発明をこの実施形態に特定することを意図するものではない。本発明は、特許請求の範囲に示した技術思想を逸脱することなく種々の変更を行ったものにも均しく適用し得るものである。 Hereinafter, embodiments for carrying out the present invention will be described in detail with various experimental examples. However, the following various experimental examples are given for the purpose of understanding the technical idea of the present invention, and are not intended to specify the present invention in this embodiment. The present invention can be equally applied to various changes made without departing from the technical idea shown in the claims.
［水素吸蔵合金の調製］
金属元素を所定のモル比となるように混合した後、これらの混合物をアルゴンガス雰囲気の高周波誘導炉に投入して溶解させ、これを金型に注入して凝固させ、下記表１に示す組成を有する実験例１〜５の鋳塊状態のＬａＳｍ系水素吸蔵合金及び表２に示す組成を有する実験例６〜８の鋳塊状態のＬａＮｄ系水素吸蔵合金を調製した。これらの水素吸蔵合金の組成は、一般式（ＬａｘＬｎｙ）１一ｚＭｇｚＮｉｔ−ｕＡｌｕ（Ｌｎ＝Ｓｍ又はＮｄ）で表される。
[Preparation of hydrogen storage alloy]
After mixing the metal elements so as to have a predetermined molar ratio, these mixtures are put into a high-frequency induction furnace in an argon gas atmosphere to be melted, poured into a mold and solidified, and the compositions shown in Table 1 below are given. The ingot-state LaSm-based hydrogen storage alloys of Experimental Examples 1 to 5 and the ingot-state LaNd-based hydrogen storage alloys having the compositions shown in Table 2 were prepared. The composition of these hydrogen storage alloy is represented by the general formula (La x Ln y) 1 one z Mg z Ni t-u Al u (Ln = Sm or Nd).
次いで、得られた各水素吸蔵合金について、ＤＳＣ（示差走査熱量計）を用いて融点（Ｔｍ）を測定した。その後、各水素吸蔵合金について、それらの融点（Ｔｍ）より低い所定温度、例えば１０２５℃（実験例１〜５）又は１０２０℃（実験例６〜８）で、所定時間、例えば１０時間、熱処理を行った。この後、これらの各水素吸蔵合金の塊を粗粉砕した後、不活性ガス雰囲気中で機械的に粉砕し、体積累積頻度５０％での粒径（Ｄ５０）が２５μｍの実験例１〜８に係る水素吸蔵合金粉末を調製した。 Subsequently, about each obtained hydrogen storage alloy, melting | fusing point (Tm) was measured using DSC (differential scanning calorimeter). Thereafter, each hydrogen storage alloy is subjected to heat treatment at a predetermined temperature lower than the melting point (Tm) thereof, for example, 1025 ° C. (Experimental Examples 1 to 5) or 1020 ° C. (Experimental Examples 6 to 8) for a predetermined time, for example, 10 hours. went. After that, these hydrogen storage alloy ingots were coarsely crushed and then mechanically pulverized in an inert gas atmosphere, and Experimental Examples 1 to 8 having a particle diameter (D 50 ) at a volume cumulative frequency of 50% of 25 μm. A hydrogen storage alloy powder was prepared.
次いで、Ｃｕ−Ｋα管をＸ線源とするＸ線回折測定装置を用いる粉末Ｘ線回折法により、実験例１〜８に係る水素吸蔵合金粉末の結晶構造の同定を行った。この場合、スキャンスピード１°／ｍｉｎ、管電圧４０ｋＶ、管電流３００ｍＡ、スキャンステップ１°、測定角度２０〜５０θ／ｄｅｇでＸ線回折測定を行った。実験例１〜５に係る水素吸蔵合金粉末の粉末Ｘ線回折チャートを図２に、実験例６〜８に係る水素吸蔵合金粉末の粉末Ｘ線回折チャートを図３に、それぞれ示した。 Subsequently, the crystal structure of the hydrogen storage alloy powder according to Experimental Examples 1 to 8 was identified by a powder X-ray diffraction method using an X-ray diffraction measurement apparatus using a Cu—Kα tube as an X-ray source. In this case, X-ray diffraction measurement was performed at a scan speed of 1 ° / min, a tube voltage of 40 kV, a tube current of 300 mA, a scan step of 1 °, and a measurement angle of 20 to 50θ / deg. A powder X-ray diffraction chart of the hydrogen storage alloy powders according to Experimental Examples 1 to 5 is shown in FIG. 2, and a powder X-ray diffraction chart of the hydrogen storage alloy powders according to Experimental Examples 6 to 8 is shown in FIG.
三方晶系（３Ｒ）のＡ５Ｂ１９型結晶構造、六方晶系（２Ｈ）のＡ５Ｂ１９型結晶構造、Ａ２Ｂ７型結晶構造は、それぞれ、２θ＝３１．４°〜３１．７°、３２．１°〜３２．４°、３２．７°〜３３．０°のピークより同定した。図２及び図３に示したチャートから、実験例１〜８のいずれの水素吸蔵合金においても、Ａ２Ｂ７型結晶構造とＡ５Ｂ１９型結晶構造が存在することが確認された。また、Ａ５Ｂ１９型結晶構造の六方晶系（２Ｈ）と三方晶系（３Ｒ）のピーク強度について、Ａ２Ｂ７型結晶構造のピーク強度を１００％とした際の相対値（％）を、実験例１〜５の測定結果については表１に、実験例６〜８の測定結果については表２に、それぞれ示した。 The trigonal (3R) A5B19 crystal structure, the hexagonal (2H) A5B19 crystal structure, and the A2B7 crystal structure are 2θ = 31.4 ° to 31.7 °, 32.1 ° to 32, respectively. It was identified from the peaks of .4 ° and 32.7 ° to 33.0 °. From the charts shown in FIGS. 2 and 3, it was confirmed that any of the hydrogen storage alloys of Experimental Examples 1 to 8 has an A2B7 crystal structure and an A5B19 crystal structure. Further, regarding the peak intensities of the hexagonal system (2H) and the trigonal system (3R) of the A5B19 type crystal structure, relative values (%) when the peak intensity of the A2B7 type crystal structure is set to 100% are shown in Experimental Examples 1 to 3. The measurement results of 5 are shown in Table 1, and the measurement results of Experimental Examples 6 to 8 are shown in Table 2.
次いで、実験例１〜８のそれぞれの水素吸歳合金粉末を、例えば８０℃で水素吸蔵放出を５回繰り返して活性化させた後、これらを４０℃の雰囲気下で、水素吸蔵量（Ｈ／Ｍ）が０．５、０．７のときの解離圧を水素平衡圧として、ＪＩＳ Ｈ７２０１（１９９１）「水素吸蔵合金の圧力一組成等温線（ＰＣＴ曲線）の測定方法」に基づいて、水素吸蔵圧及びその傾きを測定した。水素吸蔵圧の傾きは、以下の計算式により求めた。
傾き＝Ｌｏｇ（吸蔵圧（Ｈ／Ｍ＝０．７）／吸蔵圧（Ｈ／Ｍ＝０．５））
／（０．７−０．５）
実験例１〜５の測定結果を表１に、実験例６〜８の測定結果を表２に、それぞれ示した。
Next, each of the hydrogen-absorbing alloy powders of Experimental Examples 1 to 8 was activated by repeating hydrogen storage and release five times at, for example, 80 ° C., and then the hydrogen storage amount (H / Based on JIS H7201 (1991) “Method for measuring pressure-composition isotherm (PCT curve) of hydrogen storage alloy” with dissociation pressure when M) is 0.5 and 0.7 as hydrogen equilibrium pressure The pressure and its slope were measured. The slope of the hydrogen storage pressure was determined by the following formula.
Inclination = Log (Occlusion pressure (H / M = 0.7) / Occlusion pressure (H / M = 0.5))
/(0.7-0.5)
The measurement results of Experimental Examples 1 to 5 are shown in Table 1, and the measurement results of Experimental Examples 6 to 8 are shown in Table 2, respectively.
図２に示した結果から、ＬａＳｍ系のＡ５Ｂ１９型結晶構造については、実験例１の水素吸蔵合金では六方晶系（２Ｈ）が主であったが、実験例２〜５の水素吸蔵合金では三方晶系（３Ｒ）が主であることが確認された。同様に、図３に示した結果から、ＬａＮｄ系のＡ５Ｂ１９型結晶構造については、実験例６の水素吸蔵合金では六方晶系（２Ｈ）が主であったが、実験例７及び８の水素吸蔵合金では三方晶系（３Ｒ）が主であることが確認された。 From the results shown in FIG. 2, the LaSm-based A5B19 type crystal structure was mainly hexagonal (2H) in the hydrogen storage alloy of Experimental Example 1, but three-way in the hydrogen storage alloys of Experimental Examples 2-5. It was confirmed that the crystal system (3R) was predominant. Similarly, from the results shown in FIG. 3, the LaNd-based A5B19 type crystal structure was mainly hexagonal (2H) in the hydrogen storage alloy of Experimental Example 6, but the hydrogen storage of Experimental Examples 7 and 8 It was confirmed that the alloy was mainly trigonal (3R).
また、表１に示した結果から、実験例２〜５では、水素吸蔵合金中のＬａの添加量が増大するにしたがって水素吸蔵合金の平衡圧が低下しているが、実験例１では、水素吸蔵合金中のＬａの添加量が最も多いにもかかわらず、水素吸蔵合金の平衡圧が実験例２のものよりも大きくなっていることがわかる。同じく、表２に示した結果から、実験例７及び８では、水素吸蔵合金中のＬａの添加量が増大するにしたがって水素吸蔵合金の平衡圧が低下しているが、実験例６では、水素吸蔵合金中のＬａの添加量が最も多いにもかかわらず、水素吸蔵合金の平衡圧は実験例７のものとほぼ同等の結果が得られていることがわかる。このことは、水素吸蔵合金は、六方晶系（２Ｈ）のＡ５Ｂ１９型結晶構造を有するものとすることにより、水素吸蔵合金の平衡圧が上昇し、水素吸蔵合金中のＬａの添加量の増加による平衡圧力低下分が緩和されることを示すものと考えられる。 Further, from the results shown in Table 1, in Experimental Examples 2 to 5, the equilibrium pressure of the hydrogen storage alloy decreases as the amount of La added in the hydrogen storage alloy increases. It can be seen that the equilibrium pressure of the hydrogen storage alloy is higher than that of Experimental Example 2 despite the largest amount of La added in the storage alloy. Similarly, from the results shown in Table 2, in Experimental Examples 7 and 8, the equilibrium pressure of the hydrogen storage alloy decreases as the amount of La added in the hydrogen storage alloy increases. It can be seen that despite the largest amount of La added in the storage alloy, the equilibrium pressure of the hydrogen storage alloy is almost the same as that of Experimental Example 7. This is because when the hydrogen storage alloy has a hexagonal (2H) A5B19 type crystal structure, the equilibrium pressure of the hydrogen storage alloy increases, and the amount of La added in the hydrogen storage alloy increases. This is considered to indicate that the equilibrium pressure drop is relaxed.
ただし、Ｌａは水素との結合強度が強いため、Ｌａの添加量の増加により吸蔵されるが放出されない不可逆水素が増加することが想定される。しかしながら、車載用途などでは、完全放電を行なわないため、問題とならない。なお、六方晶系（２Ｈ）のＡ５Ｂ１９型結晶構造は、水素吸蔵合金の組成を特定するほか、熱処理条件等の製造条件を調整することで含有させることができる。 However, since La has a strong bond strength with hydrogen, it is assumed that irreversible hydrogen that is occluded but not released increases due to an increase in the amount of La added. However, there is no problem in in-vehicle applications because complete discharge is not performed. The hexagonal (2H) A5B19 type crystal structure can be included by specifying the composition of the hydrogen storage alloy and adjusting the manufacturing conditions such as the heat treatment conditions.
実験例１〜８では、ＬｎとしてＳｍ及びＮｄを用いた例を示した。Ｌｎとしては、Ｌａ以外の希土類元素及びＹから選択された少なくとも１種を採用することができるが、水素吸蔵合金の微粉化抑制の観点から、Ｎｄ、Ｓｍ、Ｇｄ、Ｐｒ、Ｙなどの元素が望ましい。さらに、Ｌｎとしては、Ｌａの添加量の増加による平衡圧が低下することから、平衡圧を上昇させる効果が大きいＳｍ、Ｙ、Ｇｄなどの希土類元素が望ましい。なお、水素吸蔵合金中のＬａの添加量はＬｎよりも多量、すなわち上記の水素吸蔵合金組成の一般式において、ｘ>ｙなるようにすることが好ましい。 In Experimental Examples 1 to 8, examples using Sm and Nd as Ln were shown. As Ln, at least one selected from rare earth elements other than La and Y can be used, but from the viewpoint of suppressing pulverization of the hydrogen storage alloy, elements such as Nd, Sm, Gd, Pr, and Y are used. desirable. Further, as Ln, since the equilibrium pressure is decreased due to an increase in the amount of La added, rare earth elements such as Sm, Y, and Gd that have a large effect of increasing the equilibrium pressure are desirable. It should be noted that the amount of La added in the hydrogen storage alloy is preferably larger than Ln, that is, x> y in the above general formula of the hydrogen storage alloy composition.
Ｍｇ添加量は、多すぎると微粉化及びＭｇ成分の溶解が加速し、少なすぎると結晶構造が不安定（Ｍｇを含まないＡＢ５型結晶構造の生成が顕著）となり、水素吸蔵特性が安定しない（吸蔵カーブの２段化など）。水素吸蔵特性を安定させるためには、Ａ５Ｂ１９型結晶構造を安定的に構築する必要があるため、Ｍｇ量及び希土類元素（Ｌａ＋Ｌｎ）量の合計（Ａ）と、Ｎｉ及び添加元素（Ｔ）量の合計（Ｂ）との量論比（Ｂ／Ａ）を所定の範囲にコントロールする必要がある。Ａ２Ｂ７型結晶構造は存在しても問題ないが、Ｂ／Ａが少なすぎるとＡＢ２やＡＢ３型結晶構造が、多すぎるとＡＢ５型結晶構造が混在しやすくなる。ＡＢ２やＡＢ３型結晶構造、ＡＢ５型結晶構造が混在した場合においては、サイクルに伴う微粉化が顕著となる。 If the amount of Mg added is too large, pulverization and dissolution of the Mg component accelerate, and if it is too small, the crystal structure becomes unstable (production of AB5-type crystal structure not containing Mg is remarkable) and the hydrogen storage characteristics are not stable ( (Two steps of occlusion curve). In order to stabilize the hydrogen storage characteristics, it is necessary to stably build the A5B19 type crystal structure. Therefore, the total amount of Mg and rare earth elements (La + Ln) (A), and the amount of Ni and additive elements (T) It is necessary to control the stoichiometric ratio (B / A) to the total (B) within a predetermined range. There is no problem even if an A2B7 crystal structure exists, but if the B / A is too small, the AB2 or AB3 crystal structure tends to be mixed, and if it is too much, the AB5 crystal structure tends to be mixed. In the case where AB2, AB3 type crystal structure, and AB5 type crystal structure are mixed, the pulverization accompanying the cycle becomes remarkable.
車載用途においては、いつでもアシスト（放電）できるようにするため、ＳＯＣ（充電状態：Ｓｔａｔｅ ｏｆ Ｃｈａｒｇｅ）５０％以上の充電状態で保持されており、そういった高ＳＯＣの状況で大きな出力特性が望まれる。同じく、放電に伴ってＳＯＣが低下した際には、回生充電により即座にＳＯＣ位置を回復することが必要であり、大きな回生出力特性も必要となる。このような観点から、高ＳＯＣ領域では電池電圧が高く、低ＳＯＣ領域では電池電圧が低いほうが望ましいため、水素吸蔵曲線（ＰＣＴカーブ）は、Ｈ／Ｍ＝０．５〜０．７での傾きが０．７以上３．０以下であることが望ましく、Ａ５Ｂ１９型結晶構造とＡ２Ｂ７型結晶構造からなる範囲にＢ／Ａをコントロールすることが必要である。以上の点を考慮すると、０．０９≦ｚ≦０．１４、３．６５≦ｔ≦３．８０とすることが好ましい。 In an in-vehicle application, in order to be able to assist (discharge) at any time, a state of charge (SOC) is maintained in a state of charge of 50% or more, and a large output characteristic is desired in such a high SOC state. Similarly, when the SOC decreases with discharge, it is necessary to immediately recover the SOC position by regenerative charging, and a large regenerative output characteristic is also required. From this point of view, it is desirable that the battery voltage is high in the high SOC region and low in the low SOC region. Therefore, the hydrogen storage curve (PCT curve) has a slope at H / M = 0.5 to 0.7. Is preferably 0.7 or more and 3.0 or less, and it is necessary to control B / A within a range consisting of an A5B19 type crystal structure and an A2B7 type crystal structure. Considering the above points, it is preferable that 0.09 ≦ z ≦ 0.14, 3.65 ≦ t ≦ 3.80.
実験例１〜８では、Ｔ成分としてＡｌを用いた例を示したが、他に、Ｃｏ、Ｍｎ又はＺｎを用いることができる。Ｔ成分の添加量は、少なすぎると結晶構造の安定性及び水素吸蔵量の面で不利となり、多すぎるとＴ成分の溶解の影響が顕著となるので、０．０５≦ｕ≦０．２５とすることが好ましい。 In Experimental Examples 1-8, although the example which used Al as a T component was shown, Co, Mn, or Zn can be used for others. If the amount of T component added is too small, it will be disadvantageous in terms of the stability of the crystal structure and the amount of hydrogen occlusion, and if it is too large, the effect of dissolution of the T component will be significant, so 0.05 ≦ u ≦ 0.25. It is preferable to do.
［ニッケル水素蓄電池の特性測定］
上述のようにして調製された実験例１〜８の各水素吸蔵合金を用い、以下に示すようにしてニッケル水素蓄電池を作製し、高温放置試験及び出力特性の測定を行った。
[Characteristic measurement of nickel metal hydride storage battery]
Using each of the hydrogen storage alloys of Experimental Examples 1 to 8 prepared as described above, a nickel metal hydride storage battery was produced as shown below, and a high temperature storage test and measurement of output characteristics were performed.
（水素吸蔵合金負極の作製）
上述した実験例１〜８の各水素吸蔵合金粉末と水溶性結着剤、熱可塑性エラストマー及び炭素系導電剤を混合・混練して水素吸蔵合金スラリーを調製した。水溶性結着剤としては、０．１質量％のＣＭＣ（カルボキシメチルセルロース）の水溶液を使用した。熱可塑性エラストマーとしては、スチレンブタジエンラテックス（ＳＢＲ）を使用した。炭素系導電剤としては、ケッチエンブラックを使用した。
(Production of hydrogen storage alloy negative electrode)
The hydrogen storage alloy slurries were prepared by mixing and kneading each of the hydrogen storage alloy powders of Experimental Examples 1 to 8, the water-soluble binder, the thermoplastic elastomer, and the carbon-based conductive agent. As the water-soluble binder, an aqueous solution of 0.1% by mass of CMC (carboxymethyl cellulose) was used. Styrene butadiene latex (SBR) was used as the thermoplastic elastomer. Ketchen Black was used as the carbon-based conductive agent.
上述のようにして作製した水素吸蔵合金スラリーを、ニッケルメッキを施した軟鋼材製の多孔性基板（パンチングメタル）からなる負極用導電性芯体に、所定の充填密度（例えば、５．２ｇ／ｃｍ３）となるように塗着、乾燥させた後、所定の厚みになるように圧延した。この後、所定の寸法になるように切断して、実験例１〜８のそれぞれに対応する水素吸蔵合金負極をそれぞれ作製した。 The hydrogen storage alloy slurry produced as described above is applied to a negative electrode conductive core made of a nickel-plated mild steel porous substrate (punching metal) with a predetermined packing density (for example, 5.2 g / After coating and drying so as to be cm 3 ), it was rolled to a predetermined thickness. Then, it cut | disconnected so that it might become a predetermined dimension, and produced the hydrogen storage alloy negative electrode corresponding to each of Experimental Examples 1-8, respectively.
（ニッケル正極の作製）
多孔度が約８５％の多孔性ニッケル焼結基板を比重が１．７５の硝酸ニッケル、硝酸コバルト及び硝酸亜鉛の混合水溶液に浸漬し、多孔性ニッケル焼結基板の細孔内にニッケル塩、コバルト塩及び亜鉛塩を保持させた。この後、この多孔性ニッケル焼結基板を２５質量％の水酸化ナトリウム（ＮａＯＨ）水溶液中に浸漬し、ニッケル塩、コバルト塩および亜鉛塩をそれぞれ水酸化ニッケル、水酸化コバルトおよび水酸化亜鉛に転換させた。次いで、充分に水洗してアルカリ溶液を除去した後、乾燥し、多孔性ニッケル焼結基板の細孔内に水酸化ニッケルを主成分とする正極活物質を充填した。このような活物質充填操作を所定回数（例えば６回）繰り返して、多孔性焼結基板の細孔内に水酸化ニッケルを主体とする活物質を充填密度が２．５ｇ／ｃｍ３になるように充填した。
(Preparation of nickel positive electrode)
A porous nickel sintered substrate having a porosity of about 85% is immersed in a mixed aqueous solution of nickel nitrate, cobalt nitrate and zinc nitrate having a specific gravity of 1.75, and nickel salt and cobalt are placed in the pores of the porous nickel sintered substrate. Salt and zinc salt were retained. Thereafter, this porous nickel sintered substrate is immersed in a 25% by mass aqueous sodium hydroxide (NaOH) solution to convert nickel salt, cobalt salt and zinc salt into nickel hydroxide, cobalt hydroxide and zinc hydroxide, respectively. I let you. Next, after sufficiently washing with water to remove the alkaline solution, it was dried, and the positive electrode active material mainly composed of nickel hydroxide was filled in the pores of the porous nickel sintered substrate. Such an active material filling operation is repeated a predetermined number of times (for example, 6 times) so that the active material mainly composed of nickel hydroxide is filled in the pores of the porous sintered substrate so that the filling density becomes 2.5 g / cm 3. Filled.
次いで、水酸化ニッケルを主成分とする正極活物質が充填された多孔性ニッケル焼結基板を、硝酸ニッケル及び硝酸イットリウムの混合水溶液に浸漬し、極板表面にニッケル塩及びイットリウム塩を保持させ、この後、この多孔性ニッケル焼結基板を２５質量％の水酸化ナトリウム（ＮａＯＨ）水溶液中に浸漬し、ニッケル塩及びイットリウム塩をそれぞれ水酸化ニッケルおよび水酸化イットリウムに転換させた。次いで、充分に水洗してアルカリ溶液を除去した後、乾燥し、所定の寸法に切断してニッケル正極を作製した。 Next, a porous nickel sintered substrate filled with a positive electrode active material mainly composed of nickel hydroxide is immersed in a mixed aqueous solution of nickel nitrate and yttrium nitrate, and the nickel salt and yttrium salt are held on the electrode plate surface, Thereafter, this porous nickel sintered substrate was immersed in a 25% by mass sodium hydroxide (NaOH) aqueous solution to convert the nickel salt and yttrium salt into nickel hydroxide and yttrium hydroxide, respectively. Next, after sufficiently washing with water to remove the alkaline solution, it was dried and cut into predetermined dimensions to produce a nickel positive electrode.
（アルカリ電解液の調製）
アルカリ電解液は、３０質量％の水酸化カリウム（ＫＯＨ）水溶液に、水酸化ナトリウム（ＮａＯＨ）及び水酸化リチウム（ＬｉＯＨ）を所定のモル比となるよう調製した混合水溶液に対し、タングステン酸ナトリウムをタングステン換算でアルカリ電解液１ｇあたり２０ｍｇとなるように添加したものを使用した。
(Preparation of alkaline electrolyte)
The alkaline electrolyte was prepared by adding sodium tungstate to a mixed aqueous solution prepared by adding sodium hydroxide (NaOH) and lithium hydroxide (LiOH) in a predetermined molar ratio to a 30% by mass potassium hydroxide (KOH) aqueous solution. What was added so that it might become 20 mg per 1 g of alkaline electrolyte in conversion of tungsten was used.
（ニッケル水素蓄電池の作製）
上述のように作製された水素吸蔵合金負極とニッケル正極とを用い、これらの間に、スルフォン化処理されたポリプロピレン繊維を含む不織布からなるセパレータを介在させて渦巻状に巻回して渦巻状電極群を作製した。このスルフォン化処理されたポリプロピレン繊維は、アンモニア吸着能を有している。このようにして作製された渦巻状電極群の下部こは水素吸蔵合金負極の芯体露出部が露出しており、その上部にはニッケル正極の芯体露出部が露出している。次いで、得られた渦巻状電極群の下端面に露出する芯体露出部に負極集電体を溶接するとともに、渦巻状電極群の上端面に露出するニッケル正極の芯体露出部の上に正極集電体を溶接して、電極体とした。
(Production of nickel metal hydride storage battery)
Using the hydrogen storage alloy negative electrode and the nickel positive electrode produced as described above, a separator made of nonwoven fabric containing a sulfonated polypropylene fiber is interposed therebetween, and the spiral electrode group is wound in a spiral shape. Was made. This sulfonated polypropylene fiber has an ammonia adsorption ability. In the lower part of the spiral electrode group thus produced, the core exposed part of the hydrogen storage alloy negative electrode is exposed, and the core exposed part of the nickel positive electrode is exposed above it. Next, the negative electrode current collector is welded to the core exposed portion exposed at the lower end surface of the obtained spiral electrode group, and the positive electrode is exposed on the nickel positive electrode core exposed portion exposed at the upper end surface of the spiral electrode group. The current collector was welded to obtain an electrode body.
得られた電極体を鉄にニッケルメッキを施した有底筒状の外装缶（底面の外面は負極外部端子となる）内に収納した後、負極集電体を外装缶の内底面に溶接した。正極集電体より延出する集電リード部を正極端子を兼ねるとともに外周部に絶縁ガスケットが装着された封口体の底部を構成する封口体に溶接した。なお、封口体には正極キャップが設けられていて、この正極キャップ内に所定の圧力になると変形する弁体とスプリングよりなる圧力弁が配置されている。 The obtained electrode body was housed in a bottomed cylindrical outer can made of nickel-plated iron (the outer surface of the bottom surface becomes the negative electrode external terminal), and then the negative electrode current collector was welded to the inner bottom surface of the outer can . The current collector lead portion extending from the positive electrode current collector served as the positive electrode terminal and was welded to the sealing body constituting the bottom portion of the sealing body having an insulating gasket attached to the outer peripheral portion. In addition, the positive electrode cap is provided in the sealing body, and the pressure valve which consists of the valve body and spring which deform | transform when it becomes predetermined pressure in this positive electrode cap is arrange | positioned.
次いで、外装缶の上部外周部に環状溝部を形成した後、アルカリ電解液を注液し、外装缶の上部に形成された環状溝部の上に封口体の外周部に装着された絶縁ガスケットを載置した。この後、外装缶の開口端縁をかしめ、外装缶内に上記アルカリ電解液を電池容量あたり２．５ｇ／Ａｈ注入し、実験例１〜８のそれぞれに対応するニッケル水素蓄電池を作製した。 Next, after forming an annular groove in the upper outer periphery of the outer can, an alkaline electrolyte is injected, and an insulating gasket mounted on the outer periphery of the sealing body is placed on the annular groove formed in the upper portion of the outer can. I put it. Then, the opening edge of the outer can was crimped, and the alkaline electrolyte was injected into the outer can at 2.5 g / Ah per battery capacity, and nickel hydride storage batteries corresponding to each of Experimental Examples 1 to 8 were produced.
このようにして作製されたニッケル水素蓄電池１０の具体的構成を図１を用いて説明する。ニッケル水素蓄電池１０は、上述のようにして作製されたニッケル正極１１と、水素吸蔵合金負極１２とがセパレータ１３とを介して互いに絶縁された状態で巻き回された巻回電極体１４を有している。ニッケル正極１１は、ニッケルめっき鋼板製のパンチングメタルからなる正極芯体１５の両面に形成された多孔質ニッケル焼結体内に、水酸化ニッケルを主成分とし、水酸化コバルト等が添加された正極活物質１６が充填された構成を有している。水素吸蔵合金負極１２は、ニッケルメッキした軟鋼材製のパンチングメタルからなる負極芯体１８の両面に負極活物質としての水素吸蔵合金粉末を有する負極合剤層１９が形成されている。
A specific configuration of the nickel-metal
巻回電極体１４の下部には負極芯体１８に負極集電体２０が抵抗溶接されており、巻回電極体１４の上部には正極芯体１５に正極集電体２１が抵抗溶接されている。巻回電極体１４は、鉄にニッケルメッキを施した有底円筒形の金属製の外装缶２２内に挿入されており、負極集電体２０と外装缶２２の底部との間はスポット溶接されている。
A negative electrode
外装缶２２の開放端側には、鉄にニッケルメッキを施した封口体２３が、ガスケット２４を介して外装缶２２とは電気的に絶縁された状態で、カシメ固定されている。正極集電体２１は、封口体２３に溶接されて電気的に接続されている。正極集電体２１の中央部には開口２５が設けられており、この開口２５には弁体２６が開口２５を塞ぐように配置されている。
On the open end side of the
また、封口体２３の上面には、開口２５の周囲を覆い、かつ、弁体２６とは一定距離だけ隔てた状態となるように、正極キャップ２７が設けられている。正極キャップ２７には、適宜ガス抜き孔（図示省略）が設けられている。正極キャップ２７の内面と弁体２６との間にはバネ２８が設けられており、弁体２６はバネ２８によって封口体２３の開口２５を塞ぐように押圧されている。この弁体２６は外装缶２２の内部の圧力が高くなった際に、内部の圧力を逃がす安全弁としての機能を有している。
Further, a positive electrode cap 27 is provided on the upper surface of the sealing
（ニッケル水素蓄電池の活性化）
上述のようにして作製された実験例１〜８に対応するそれぞれの円筒状ニッケル水素蓄電池を、それぞれ２５℃に維持された恒温槽中で、１Ｉｔの充電電流でＳＯＣが１２０％となるまで充電し、次いで、７０℃に維持された恒温槽中で２４時間放置した後、４５℃に維持された恒温槽中で、１Ｉｔの放電電流で電池電圧が０．３Ｖになるまで放電させた。この充放電サイクルを１サイクルとして２サイクル繰り返して、電池を活性化した。
(Activation of NiMH batteries)
Each cylindrical nickel-metal hydride storage battery corresponding to Experimental Examples 1 to 8 manufactured as described above was charged in a thermostat maintained at 25 ° C. until the SOC became 120% with a charging current of 1 It. Then, after being left for 24 hours in a thermostat maintained at 70 ° C., the battery was discharged in a thermostat maintained at 45 ° C. until the battery voltage became 0.3 V with a discharge current of 1 It. The battery was activated by repeating this charge / discharge cycle as one cycle for two cycles.
次いで、活性化された実験例１〜８に対応するそれぞれの円筒状ニッケル水素蓄電池に対して、２５℃に維持された恒温槽中で、０．５Ｉｔの定電流でＳＯＣが１２０％となるまで充電し、１時間放置した後、１Ｉｔの放電電流で電池電圧が０．９Ｖになるまで放電させた。この充放電サイクルを３サイクル繰り返した。 Next, for each of the cylindrical nickel-metal hydride storage batteries corresponding to the activated Experimental Examples 1 to 8, in a thermostat maintained at 25 ° C., until the SOC becomes 120% at a constant current of 0.5 It. The battery was charged and allowed to stand for 1 hour, and then discharged at a discharge current of 1 It until the battery voltage reached 0.9V. This charge / discharge cycle was repeated three times.
（高温放置試験）
水素吸蔵合金の耐食性を調べるために、以下の評価を実施した。上述のようにして活性化した実験例１〜８のそれぞれに対応する円筒形ニッケル水素蓄電池の電池質量を測定した後、２５℃の温度雰囲気で１Ｉｔの充電電流でＳＯＣの８０％まで充電した後、８０℃の温度雰囲気で１週間放置させた。次いで、２５℃の温度雰囲気下で１Ｉｔの放電電流で、電池電圧が０．９Ｖになるまで放電させた。このような充電放置を６回（実験例１〜５）又は５回（実験例６〜８）繰り返した。
(High temperature storage test)
In order to investigate the corrosion resistance of the hydrogen storage alloy, the following evaluation was performed. After measuring the battery mass of the cylindrical nickel metal hydride storage battery corresponding to each of Experimental Examples 1 to 8 activated as described above, after charging to 80% of SOC at a charging current of 1 It in a temperature atmosphere of 25 ° C. , And allowed to stand at 80 ° C. for 1 week. Next, the battery was discharged with a discharge current of 1 It in a temperature atmosphere of 25 ° C. until the battery voltage became 0.9V. Such charge leaving was repeated 6 times (Experimental Examples 1 to 5) or 5 times (Experimental Examples 6 to 8).
（出力特性評価）
８０℃の温度雰囲気での放置前及び放置後の実験例１〜８のそれぞれに対応する円筒形ニッケル水素蓄電池の低温出力特性評価を以下のように測定した。上述のようにして活性化した実験例１〜８のそれぞれに対応する円筒形ニッケル水素蓄電池を２５℃の温度雰囲気で１Ｉｔの充電電流でＳＯＣの５０％まで充電した後、−１０℃の温度雰囲気で３時間休止させた。次いで、−１０℃の温度雰囲気で、以下に示す所定の充電レートで２０秒間充電させた後、−１０℃の温度雰囲気で３０分間休止させた。この後、−１０℃の温度雰囲気で、以下に示す所定の放電レートで１０秒間放電させた後、−１０℃の温度雰囲気で３０分間休止させた。このような−１０℃の温度雰囲気での所定の充電レートでの２０秒間充電、３０分の休止、所定の放電レートで１０秒間放電、一１０℃の温度雰囲気での３０分の休止を繰り返した。
(Output characteristic evaluation)
The low-temperature output characteristic evaluation of the cylindrical nickel-metal hydride storage battery corresponding to each of Experimental Examples 1 to 8 before and after being left in an 80 ° C. temperature atmosphere was measured as follows. The cylindrical nickel metal hydride storage batteries corresponding to each of Experimental Examples 1 to 8 activated as described above were charged to 50% of SOC at a charging current of 1 It in a temperature atmosphere of 25 ° C., and then the temperature atmosphere of −10 ° C. And rested for 3 hours. Next, the battery was charged for 20 seconds at a predetermined charging rate shown below in a temperature atmosphere of −10 ° C., and then rested for 30 minutes in a temperature atmosphere of −10 ° C. Thereafter, the battery was discharged for 10 seconds at a predetermined discharge rate shown below in a temperature atmosphere of −10 ° C., and then rested for 30 minutes in a temperature atmosphere of −10 ° C. Such a 20 second charge at a predetermined charge rate in a temperature atmosphere of −10 ° C., a 30 minute pause, a 10 second discharge at a predetermined discharge rate, and a 30 minute pause in a temperature atmosphere of 10 ° C. were repeated. .
この場合、所定の充電レートは０．８Ｉｔ−１．７Ｉｔ−２．５Ｉｔ−３．３１ｔ−４．２１ｔの順で充電電流を増加させ、所定の放電レートは、１．７Ｉｔ−３．３Ｉｔ−５．０Ｉｔ−６．７Ｉｔ−８．３Ｉｔの順で放電電流を増加させるものであり、各放電レートで１０秒間経過時点での各電池の電池電圧（Ｖ）を放電レート毎に測定した。次いで、測定した１０秒間経過時点での各電池の電池電圧（Ｖ）を放電レート毎の放電電流値に対して２次元プロットし、電池電圧と放電電流値の関係を示す近似曲線を求め、近似曲線における０．９Ｖ時の放電電流値をＳＯＣ５０％出力特性として求めた。実験例１〜５のＬａＳｍ系の測定結果は、実験例１の測定結果を１００とした相対値で表３の「初期」の欄に示し、実験例６〜８のＬａＮｄ系は実験例６の測定結果を１００とした相対値で表４の「初期」の欄に示した。
In this case, the predetermined charging rate increases the charging current in the order of 0.8 It−1.7 It−2.5 It−3.31 t−4.21 t, and the predetermined discharging rate is 1.7 It−3.3 It−. The discharge current was increased in the order of 5.0 It-6.7 It-8.3 It, and the battery voltage (V) of each battery when 10 seconds passed at each discharge rate was measured for each discharge rate. Then, the measured battery voltage (V) of each battery at the time point of 10 seconds is two-dimensionally plotted with respect to the discharge current value for each discharge rate to obtain an approximate curve indicating the relationship between the battery voltage and the discharge current value. The discharge current value at 0.9 V in the curve was determined as
次いで、高温放置後の実験例１〜８のそれぞれに対応する円筒形ニッケル水素蓄電池について、上記の場合と同様にして、ＳＯＣ５０％出力特性を求めた。実験例１〜５のＬａＳｍ系の測定結果は実験例１の測定結果を１００とした相対値で表３の「劣化後」の欄に示し、実験例６〜８のＬａＮｄ系は実験例６の測定結果を１００とした相対値で表４の「劣化後」の欄に示した。
Next, the
なお、表３及び表４の「初期×劣化後」の欄は、「初期」の出力特性及び「劣化後」の出力特性を総合的に勘案するため、「初期」の測定結果と「劣化後」の測定結果の積について、実験例１〜５のＬａＳｍ系の測定結果は実験例１の測定結果を１００とした相対値で表３に示し、実験例６〜８のＬａＮｄ系は実験例６の測定結果を１００とした相対値で表４に示したものである。 In addition, in the columns of “Initial × After Degradation” in Tables 3 and 4, the “Initial” measurement results and “After Degradation” are taken into account in order to comprehensively consider the “Initial” output characteristics and “After Degradation” output characteristics. The measurement results of the LaSm system of Experimental Examples 1 to 5 are shown in Table 3 as relative values with the measurement result of Experimental Example 1 being 100, and the LaNd systems of Experimental Examples 6 to 8 are Experimental Example 6 Table 4 shows the relative values with the measurement result of 100 as 100.
これらの表３及び表４に示した結果から明らかなように、実験例１及び実験例６に対応するニッケル水素蓄電池においては、実験例２〜５ないし実験例７、８に対応するニッケル水素蓄電池よりもＬａ添加量が多い（コスト安価）にもかかわらず、初期特性の低下が抑制され、また、劣化後（高温放置後）においても充放電特性の優位性を保っており、初期と劣化後の特性バランスに優れていることが確認できた。特に、実験例１に対応するニッケル水素蓄電池においては、実施例２のものに対し、よりＬａ添加量を増大させることが可能となっており、コスト面でも優位であることが明らかである。 As is clear from the results shown in Tables 3 and 4, in the nickel metal hydride storage batteries corresponding to Experimental Examples 1 and 6, the nickel hydrogen storage batteries corresponding to Experimental Examples 2 to 5 to Experimental Examples 7 and 8 are used. In spite of the addition amount of La (cost is low), the deterioration of the initial characteristics is suppressed, and the superiority of the charge / discharge characteristics is maintained even after deterioration (after leaving at high temperature). It was confirmed that the balance of characteristics was excellent. In particular, in the nickel metal hydride storage battery corresponding to Experimental Example 1, it is possible to increase the amount of La added more than that of Example 2, and it is clear that the cost is superior.
１０…ニッケル水素蓄電池 １１…ニッケル正極 １２…水素吸蔵合金負極
１３…セパレータ １４…巻回電極体 １５…正極芯体
１６…正極活物質 １８…負極芯体 １９…負極合剤層
２０…負極集電体 ２１…正極集電体 ２２…外装缶
２３…封口体 ２４…ガスケット ２５…開口
２６…弁体 ２７…正極キャップ ２８…バネ
DESCRIPTION OF
Claims (2)
水酸化ニッケルを主成分とするニッケル正極と、
セパレータとからなる電極群をアルカリ電解液とともに外装缶内に備えたアルカリ蓄電池であって、
前記水素吸蔵合金は、Ｌａを主要希土類元素とする一般式（ＬａｘＬｎｙ）１一ｚＭｇｚＮｉｔ−ｕＴｕ（Ｔ：Ａｌ、Ｃｏ、Ｍｎ、Ｚｎから選択され、ＬｎはＬａ以外の希土類元素及びＹから選択された少なくとも１種であり、ｘ>ｙ、０．０９≦ｚ≦０．１４、３．６５≦ｔ≦３．８０、０．０５≦ｕ≦０．２５）であって、六方晶系（２Ｈ）のＡ５Ｂ１９型結晶構造のものと、三方晶系（３Ｒ）のＡ５Ｂ１９型結晶構造のものと、Ａ２Ｂ７型結晶構造のものとを含み、
前記六方晶系（２Ｈ）のＡ５Ｂ１９型結晶構造のもののＣｕ−Ｋα線による粉末Ｘ線回折強度ピークは、前記三方晶系（３Ｒ）のＡ５Ｂ１９型結晶構造のもの及びＡ２Ｂ７型結晶構造のものよりも大きい、
アルカリ蓄電池。 A hydrogen storage alloy negative electrode mainly composed of a hydrogen storage alloy;
A nickel positive electrode mainly composed of nickel hydroxide;
An alkaline storage battery comprising an electrode group consisting of a separator and an alkaline electrolyte in an outer can,
The hydrogen storage alloy is selected from the general formula (La x Ln y ) 11 z Mg z Ni tu- Tu (T: Al, Co, Mn, Zn) in which La is a main rare earth element, and Ln is other than La X> y, 0.09 ≦ z ≦ 0.14, 3.65 ≦ t ≦ 3.80, 0.05 ≦ u ≦ 0.25) A hexagonal (2H) A5B19 crystal structure, a trigonal (3R) A5B19 crystal structure, and an A2B7 crystal structure,
The powder X-ray diffraction intensity peak by Cu-Kα ray of the hexagonal (2H) A5B19 crystal structure is higher than that of the trigonal (3R) A5B19 crystal structure and A2B7 crystal structure. large,
Alkaline storage battery.
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