JP2014110148A - Solid electrolyte material and metal-air whole solid secondary battery using the same - Google Patents
Solid electrolyte material and metal-air whole solid secondary battery using the same Download PDFInfo
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- 239000007784 solid electrolyte Substances 0.000 title claims abstract description 86
- 239000000463 material Substances 0.000 title claims abstract description 29
- 239000007787 solid Substances 0.000 title claims abstract description 25
- GDVKFRBCXAPAQJ-UHFFFAOYSA-A dialuminum;hexamagnesium;carbonate;hexadecahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Al+3].[Al+3].[O-]C([O-])=O GDVKFRBCXAPAQJ-UHFFFAOYSA-A 0.000 claims abstract description 22
- 229910001701 hydrotalcite Inorganic materials 0.000 claims abstract description 21
- 229960001545 hydrotalcite Drugs 0.000 claims abstract description 21
- -1 hydroxide ions Chemical group 0.000 claims abstract description 17
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims abstract description 8
- 150000001450 anions Chemical class 0.000 claims abstract description 8
- 229910052751 metal Inorganic materials 0.000 claims description 120
- 239000002184 metal Substances 0.000 claims description 120
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 54
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 29
- 229910052799 carbon Inorganic materials 0.000 claims description 24
- 229910052742 iron Inorganic materials 0.000 claims description 23
- 239000003054 catalyst Substances 0.000 claims description 19
- 239000002131 composite material Substances 0.000 claims description 17
- 150000008044 alkali metal hydroxides Chemical group 0.000 claims description 12
- 229910052760 oxygen Inorganic materials 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 11
- 239000001301 oxygen Substances 0.000 claims description 11
- 230000009467 reduction Effects 0.000 claims description 8
- 239000011229 interlayer Substances 0.000 claims description 7
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 104
- 239000003792 electrolyte Substances 0.000 description 25
- 239000004020 conductor Substances 0.000 description 22
- 239000000843 powder Substances 0.000 description 21
- 239000010410 layer Substances 0.000 description 18
- 239000002245 particle Substances 0.000 description 11
- 239000002001 electrolyte material Substances 0.000 description 10
- 238000000034 method Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000006722 reduction reaction Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000001035 drying Methods 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- 239000011812 mixed powder Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000000499 gel Substances 0.000 description 3
- 239000000017 hydrogel Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
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- 238000009751 slip forming Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910001339 C alloy Inorganic materials 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- QANIADJLTJYOFI-UHFFFAOYSA-K aluminum;magnesium;carbonate;hydroxide;hydrate Chemical compound O.[OH-].[Mg+2].[Al+3].[O-]C([O-])=O QANIADJLTJYOFI-UHFFFAOYSA-K 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- OJIJEKBXJYRIBZ-UHFFFAOYSA-N cadmium nickel Chemical compound [Ni].[Cd] OJIJEKBXJYRIBZ-UHFFFAOYSA-N 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
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- 150000001875 compounds Chemical class 0.000 description 1
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- 238000010494 dissociation reaction Methods 0.000 description 1
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- 230000000694 effects Effects 0.000 description 1
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- 238000002848 electrochemical method Methods 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
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- 239000002360 explosive Substances 0.000 description 1
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- 239000011888 foil Substances 0.000 description 1
- 239000011245 gel electrolyte Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
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- 238000004544 sputter deposition Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 210000002268 wool Anatomy 0.000 description 1
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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- Hybrid Cells (AREA)
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Abstract
Description
本発明は固体電解質材料およびこれを用いた全固体二次電池に関するものである。 The present invention relates to a solid electrolyte material and an all-solid secondary battery using the same.
二次電池の中で、現在最もエネルギー密度（電池質量に対する放電可能な電力量）が高いと考えられているのはリチウムイオン電池であるが、リチウムイオン電池のエネルギー密度を超える二次電池の一つとして、金属−空気二次電池が注目されている。金属−空気二次電池は、正極の反応物質が空気中の酸素であり、負極が金属である。この金属−空気二次電池の最大の特徴は、正極で大気中の酸素を活用しているため正極の反応物質の質量を理論上ゼロにできる点にある。電池の質量は、正・負電極での反応物質の重さと、反応を仲介する電解質の重さが大部分を占めるため、片方の電極の反応物質をゼロにできる金属−空気二次電池は、エネルギー密度を飛躍的に向上できる可能性がある。 Among the secondary batteries, the lithium ion battery is considered to have the highest energy density (the amount of electric power that can be discharged with respect to the battery mass) at present, but the secondary battery exceeds the energy density of the lithium ion battery. For example, metal-air secondary batteries have attracted attention. In the metal-air secondary battery, the reactant of the positive electrode is oxygen in the air, and the negative electrode is metal. The greatest feature of this metal-air secondary battery is that, since oxygen in the atmosphere is utilized at the positive electrode, the mass of the reactant in the positive electrode can theoretically be reduced to zero. The mass of the battery is mostly the weight of the reaction material at the positive and negative electrodes and the weight of the electrolyte that mediates the reaction, so the metal-air secondary battery that can make the reaction material of one electrode zero, There is a possibility that the energy density can be dramatically improved.
従来、金属−空気電池は、炭素粉末などの導電材と酸素還元触媒とを組み合わせた空気極を正極とし、亜鉛、アルミニウム、鉄、水素などを負極とし、電解質としては例えばアルカリ性水溶液のような液体を備えるものであった。一般に、アルカリ性水溶液のような水溶液電解質は、アルカリ性が強いため腐食による液漏れを封止する必要があり、持ち運びの点で課題がある。また、水溶液を用いるためにエネルギー密度の向上には限界がある。例えば特許文献１には、イオン液体を用いた電池が提案されているが、制御が難しいとともに、上述の通り液体であるために液漏れ等の課題は解決されていない。これに対して、近年、有機溶媒電解液や有機高分子ゲル電解質を用いた電池もあるが、これらの電解質は揮発性や可燃性であるため、未使用状態での長期保存によって電解液が枯渇したり劣化したりする可能性がある。また電池が破損した場合には、可燃性成分により爆発的な破壊を生じる危険性もある。 Conventionally, a metal-air battery has an air electrode in which a conductive material such as carbon powder and an oxygen reduction catalyst are combined as a positive electrode, zinc, aluminum, iron, hydrogen, or the like as a negative electrode, and an electrolyte such as an alkaline aqueous solution. It was equipped with. In general, an aqueous electrolyte such as an alkaline aqueous solution has strong alkalinity, so that it is necessary to seal liquid leakage due to corrosion, and there is a problem in carrying it. In addition, since an aqueous solution is used, there is a limit to improving the energy density. For example, Patent Document 1 proposes a battery using an ionic liquid, but it is difficult to control and, as described above, it is a liquid, and thus problems such as liquid leakage are not solved. In contrast, in recent years, there are batteries that use organic solvent electrolytes or organic polymer gel electrolytes, but these electrolytes are volatile and flammable, so the electrolytes are depleted by long-term storage in unused conditions. Or may deteriorate. Further, when the battery is damaged, there is a risk of causing explosive destruction due to combustible components.
よって、電解質を非有機物で形成することが望まれている。近年では、層状構造を有する無機複合酸化物の粘土鉱物、特にハイドロタルサイトを用いたヒドロゲル電解質が、水溶性電解液の場合と同様の電気化学特性を有するため、全固体型二次電池用の電解質として提案されている（例えば特許文献２）。この技術は、層間に単に水溶液を保持するのでなく、アルカリ水溶液電解質を用いてゲル化しても層状構造の壊れない無機ヒドロゲル電解質とすることにより、電気化学特性の良い全固体アルカリ二次電池用無機電解質を得るものである。しかし、上記特許文献２の技術のヒドロゲル電解質は、ハイドロタルサイトに対するＫＯＨのモル比が１７から３０と多いため、イオン伝導性は高いが、電解質が空気中の水分を吸収するため、アルカリ水溶液の漏洩が懸念される。 Therefore, it is desired to form the electrolyte with a non-organic substance. In recent years, clay minerals of inorganic composite oxides with a layered structure, especially hydrogel electrolytes using hydrotalcite, have the same electrochemical characteristics as in the case of water-soluble electrolytes. It has been proposed as an electrolyte (for example, Patent Document 2). This technology does not simply hold an aqueous solution between the layers, but by forming an inorganic hydrogel electrolyte that does not break the layered structure even when gelled using an alkaline aqueous electrolyte, it is an inorganic material for all solid alkaline secondary batteries with good electrochemical characteristics. An electrolyte is obtained. However, since the hydrogel electrolyte of the technique of Patent Document 2 has a high KOH to hydrotalcite ratio of 17 to 30 and thus has high ionic conductivity, the electrolyte absorbs moisture in the air, so There is concern about leakage.
本発明は、上記事情に鑑みてなされたものであり、イオン伝導性が高くかつ安定的な金属−空気全固体二次電池を得るべく、該金属−空気全固体二次電池の固体電解質の主成分を非有機物で形成することを目的とする。 The present invention has been made in view of the above circumstances. In order to obtain a stable metal-air all-solid secondary battery having high ion conductivity, the main component of the solid electrolyte of the metal-air all-solid secondary battery is as follows. The purpose is to form the components with non-organic substances.
上記課題を解決し得た本発明の固体電解質材料は、キセロゲル状のハイドロタルサイトを用いた固体電解質材料であって、該ハイドロタルサイトの層間アニオンである炭酸イオンの少なくとも一部が、水酸化物イオンに置換されている点に特徴を有する。
前記固体電解質材料は、前記ハイドロタルサイトと、アルカリ金属水酸化物とが複合体を形成したものであることが好ましい。
また本発明には、炭素と酸素還元触媒を含む空気極と、金属（好ましくは鉄）を含む金属極と、第１の固体電解質とを備えた金属−空気全固体二次電池であって、前記第１の固体電解質が、前記固体電解質材料からなる点に特徴を有する金属−空気全固体二次電池も含まれる。
The solid electrolyte material of the present invention capable of solving the above problems is a solid electrolyte material using xerogel-like hydrotalcite, wherein at least a part of carbonate ions which are interlayer anions of the hydrotalcite are hydroxylated. It is characterized by the fact that it is replaced by a product ion.
The solid electrolyte material is preferably a composite of the hydrotalcite and the alkali metal hydroxide.
The present invention also provides a metal-air all-solid secondary battery comprising an air electrode containing carbon and an oxygen reduction catalyst, a metal electrode containing a metal (preferably iron), and a first solid electrolyte, A metal-air all-solid secondary battery characterized in that the first solid electrolyte is made of the solid electrolyte material is also included.
本発明に係る固体電解質によれば、キセロゲル状の層状水酸化物（ＬＤＨ）であるハイドロタルサイト［Ｍｇ2+ 1-xＡｌ3+ x（ＯＨ）2］Ａn- x/n・ｍＨ2Ｏを用いた電解質材料であって、層間アニオンである炭酸イオンの少なくとも一部が水酸化物イオンに置換されていることから、室温であっても十分な伝導性（例えば１０-3Ｓ／ｃｍ程度）を発揮することができる。上記の通り、特にゲルを乾燥させたキセロ（ドライ）ゲル状のハイドロタルサイトを用いるため耐水性に優れている。また、この固体電解質は、例えば金属−空気全固体二次電池に有用であり、本発明の固体電解質を用いた金属−空気全固体二次電池は、充電−放電が可能であり、二次電池として十分に作動させることができる。 According to the solid electrolyte of the present invention, hydrotalcite [Mg 2+ 1-x Al 3+ x (OH) 2 ] A n− x / n · mH 2 which is a xerogel-like layered hydroxide (LDH). An electrolyte material using O, in which at least part of carbonate ions as interlayer anions is substituted with hydroxide ions, so that sufficient conductivity (for example, 10 −3 S / cm) can be obtained even at room temperature. Degree). As described above, in particular, xero (dry) gel hydrotalcite obtained by drying the gel is used, so that the water resistance is excellent. The solid electrolyte is useful for, for example, a metal-air all solid secondary battery, and the metal-air all solid secondary battery using the solid electrolyte of the present invention can be charged and discharged. Can be fully operated as.
本発明者らは、有機固体電解質に代わる新たな固体の電解質について検討した。その結果、層状水酸化物（ＬＤＨ）であるハイドロタルサイト［Ｍｇ2+ 1-xＡｌ3+ x（ＯＨ）2］Ａn- x/n・ｍＨ2Ｏで構成されるキセロゲルを用いた電解質材料であって、該ハイドロタルサイトの層間アニオンである炭酸イオンの少なくとも一部が、水酸化物イオンに置換されたものが、水酸化物イオンを高度に伝導でき、電解質材料として有用であることが明らかとなり、非有機（無機）固体電解質を実現するに至った。 The present inventors examined a new solid electrolyte to replace the organic solid electrolyte. As a result, an electrolyte using a xerogel composed of hydrotalcite [Mg 2+ 1-x Al 3+ x (OH) 2 ] A n- x / n · mH 2 O which is a layered hydroxide (LDH) A material in which at least a portion of carbonate ions, which are interlayer anions of the hydrotalcite, is substituted with hydroxide ions can highly conduct hydroxide ions and is useful as an electrolyte material As a result, non-organic (inorganic) solid electrolytes were realized.
前記電解質材料として、ハイドロタルサイトがアルカリ金属水酸化物と複合体を形成したものであれば、上記複合体を構成するアルカリ金属水酸化物の少なくとも一部の解離により生じた水酸化物イオンが、ハイドロタルサイトの層間アニオンである炭酸イオンの少なくとも一部と、置換されて、上記本発明の電解質材料が得られる。 If the hydrotalcite forms a complex with an alkali metal hydroxide as the electrolyte material, hydroxide ions generated by dissociation of at least a part of the alkali metal hydroxide constituting the complex The electrolyte material of the present invention is obtained by substituting at least a part of the carbonate ion which is an interlayer anion of hydrotalcite.
上記ハイドロタルサイトのキセロゲルを用いれば、アルカリ金属水酸化物等の塩基性水酸化物の存在下、すなわち強アルカリ性の環境下でも安定なゲル化物が得られる。 If the hydrotalcite xerogel is used, a stable gelled product can be obtained even in the presence of a basic hydroxide such as an alkali metal hydroxide, that is, in a strongly alkaline environment.
なお、前記のゲル化物は、水酸化物イオンがインターカレーションしていれば良く、層間アニオンとして、他のイオン（例えば炭酸イオン）などが結合または残留していても良い。 In addition, the gelled material is sufficient if hydroxide ions are intercalated, and other ions (for example, carbonate ions) may be bonded or remain as interlayer anions.
本発明の電解質材料は、後記に詳述する通り、ハイドロタルサイト（粉末）とアルカリ金属水酸化物（溶液）とを混合、撹拌してゲル化物（中間ゲル化物）を生成し、このゲル化物を乾燥することで得られる。 As described in detail later, the electrolyte material of the present invention is a mixture of hydrotalcite (powder) and alkali metal hydroxide (solution) and stirred to produce a gelled product (intermediate gelled product). Is obtained by drying.
前記アルカリ金属水酸化物としては、水酸化物イオンを遊離し得る化合物を使用できる。この様なアルカリ金属水酸化物を使用することで、上述の通り、上記ハイドロタルサイトの層間アニオンである炭酸イオンの少なくとも一部が水酸化物イオンに置換される。その結果、この水酸化物イオン（ＯＨ-イオン）が固体電解質内を移動可能となり、電解質の伝導性を高めることができる。前記アルカリ金属水酸化物は、水酸化リチウム、水酸化ナトリウム、水酸化カリウムなどが好ましく、特に水酸化カリウムが好ましい。 As the alkali metal hydroxide, a compound capable of liberating hydroxide ions can be used. By using such an alkali metal hydroxide, as described above, at least a part of the carbonate ions that are interlayer anions of the hydrotalcite are replaced with hydroxide ions. As a result, the hydroxide ions (OH - ions) can move in the solid electrolyte, and the conductivity of the electrolyte can be increased. The alkali metal hydroxide is preferably lithium hydroxide, sodium hydroxide, potassium hydroxide or the like, and particularly preferably potassium hydroxide.
アルカリ金属水酸化物として水酸化カリウム（ＫＯＨ）を用いた場合、ハイドロタルサイト（ＬＤＨ）に対するＫＯＨのモル比（ｘ）は１以上とすることが好ましく、より好ましい値は２程度である。 When potassium hydroxide (KOH) is used as the alkali metal hydroxide, the molar ratio (x) of KOH to hydrotalcite (LDH) is preferably 1 or more, and a more preferable value is about 2.
本発明の電解質材料は、ハイドロタルサイト粉末を出発原料として、該粉末とＫＯＨなどのアルカリ金属水酸化物溶液とを、室温または５０℃程度（例えば４０〜８０℃）で撹拌し、得られたゲル化物を６０℃程度の温度で乾燥させることで得ることができる。前記電解質材料の製造方法としては、例えば共沈法を用いることができる。 The electrolyte material of the present invention was obtained by using hydrotalcite powder as a starting material and stirring the powder and an alkali metal hydroxide solution such as KOH at room temperature or about 50 ° C. (for example, 40 to 80 ° C.). It can be obtained by drying the gelled product at a temperature of about 60 ° C. As a manufacturing method of the electrolyte material, for example, a coprecipitation method can be used.
中間ゲル化物が生成する限り、上記放置の温度条件等は特に限定されないが、例えば４０〜８０℃程度で保持する場合には、生成完了までに通常１〜２日間程度を要する。 As long as the intermediate gelled product is generated, the temperature condition of the standing is not particularly limited. However, for example, when it is held at about 40 to 80 ° C., it usually takes about 1 to 2 days to complete the generation.
中間ゲル化物を乾燥処理することで、本発明の固体電解質材料（最終ゲル化物）を得ることができる。乾燥（熱処理）温度は、アルカリ金属水酸化を用いる場合、６０〜８０℃程度とすれば、得られるゲル粉末の結晶性を高めることができ、室温付近でも高い導電率を確保できる。 By drying the intermediate gelled product, the solid electrolyte material (final gelled product) of the present invention can be obtained. When alkali metal hydroxide is used as the drying (heat treatment) temperature, the crystallinity of the gel powder obtained can be increased and high conductivity can be ensured even near room temperature.
上記固体電解質材料の用途は特に限定されず、金属−空気二次電池、ニッケル水素電池、またはニッケルカドミウム電池などに用いることができる。特には、空気極と、金属を含む金属極を備える上記金属−空気全固体二次電池に用いるのが好ましい。 The use of the solid electrolyte material is not particularly limited, and can be used for a metal-air secondary battery, a nickel metal hydride battery, a nickel cadmium battery, or the like. In particular, it is preferably used for the metal-air all-solid secondary battery including an air electrode and a metal electrode containing a metal.
前記金属−空気全固体二次電池の態様（態様Ａ）として、炭素と酸素還元触媒を含む空気極と、金属を含む金属極と、第１の固体電解質とを備えた、金属−空気全固体二次電池であって、前記第１の固体電解質が、本発明の固体電解質材料であるものが好ましい。具体的態様として、前記固体電解質（第１の固体電解質）の一方側に、炭素と酸素還元触媒を含む空気極（好ましくは触媒付きカーボン層）が設けられ、他方側に、金属を含む金属極が設けられたものが挙げられる。 As an aspect (aspect A) of the metal-air all solid secondary battery, a metal-air all solid comprising an air electrode containing carbon and an oxygen reduction catalyst, a metal electrode containing a metal, and a first solid electrolyte. A secondary battery is preferable in which the first solid electrolyte is the solid electrolyte material of the present invention. As a specific aspect, an air electrode (preferably a carbon layer with a catalyst) containing carbon and an oxygen reduction catalyst is provided on one side of the solid electrolyte (first solid electrolyte), and a metal electrode containing a metal on the other side. Are provided.
前記金属−空気全固体二次電池の別の態様（態様Ｂ）として、炭素と酸素還元触媒を含む空気極と、金属と導体と第２の固体電解質とを含む金属極と、第１の固体電解質とを備えた、金属−空気全固体二次電池であって、前記第１と第２の固体電解質が同一又は異なって、本発明の電解質材料である金属−空気全固体二次電池が好ましい態様として挙げられる。具体的には、前記空気極、第１の固体電解質、金属極がこの順に備えられ、前記金属極が、金属と導体と第２の固体電解質とを含むもの（例えば、下記に示す通り、第２の固体電解質の各粒子表面に金属が直接かつ部分的に形成され、かつ該金属の形成された第２の固体電解質と導体との混合体）が挙げられる。 As another aspect (aspect B) of the metal-air all-solid secondary battery, an air electrode including carbon, an oxygen reduction catalyst, a metal electrode including a metal, a conductor, and a second solid electrolyte, and a first solid A metal-air all-solid secondary battery comprising an electrolyte, wherein the first and second solid electrolytes are the same or different, and a metal-air all-solid secondary battery that is the electrolyte material of the present invention is preferred. It is mentioned as an aspect. Specifically, the air electrode, the first solid electrolyte, and the metal electrode are provided in this order, and the metal electrode includes a metal, a conductor, and a second solid electrolyte (for example, as shown below, And a mixture of a second solid electrolyte and a conductor in which a metal is directly and partially formed on each particle surface of the solid electrolyte and the metal is formed.
上記電池における第１と第２の固体電解質層の厚み（第２の固体電解質の場合、金属極（負極）を構成する固体電解質層の厚みをいう）は、水酸化物イオンを伝導するという作用を十分に発揮させ、短絡を防ぐために０．１ｍｍ程度が好ましい。一方、固体電解質層の厚みが厚くなりすぎると、実抵抗（電池内部抵抗）が大きくなり、電流を取り出せなくなるという不具合が生じる。そこで固体電解質層の厚みは０．３ｍｍ以下とすることが好ましい。 The thickness of the first and second solid electrolyte layers in the battery (in the case of the second solid electrolyte, the thickness of the solid electrolyte layer constituting the metal electrode (negative electrode)) acts to conduct hydroxide ions. Is preferably about 0.1 mm in order to sufficiently exhibit the above and prevent short circuit. On the other hand, when the thickness of the solid electrolyte layer becomes too thick, the actual resistance (battery internal resistance) increases, resulting in a problem that current cannot be extracted. Therefore, the thickness of the solid electrolyte layer is preferably 0.3 mm or less.
次に、金属極について詳述する。前記金属極は、金属−空気全固体二次電池の負極として作用するものであり、用いる金属をＭとすると、下記（１）式の反応が生じている。
Ｍ ＋ ｘ(ＯＨ-) → Ｍ(ＯＨ)x ＋ ｘｅ- …（１）
Next, the metal electrode will be described in detail. The metal electrode functions as a negative electrode of a metal-air all-solid secondary battery. When the metal used is M, a reaction of the following formula (1) occurs.
M + x (OH − ) → M (OH) x + xe − (1)
前記金属極に用いられる金属として、亜鉛、アルミニウム、リチウム、鉄、マグネシウム等が挙げられるが、その中でも、鉄、アルミニウム、マグネシウムが好ましい。マグネシウムは、リチウムなどとは異なり豊富に存在する元素であり、電池の電圧の向上が期待できる。また、前記鉄とは、鉄合金や鉄含有物質も含む意味である。鉄は、酸化還元電位の絶対値は比較的小さいが、そのイオン化物（鉄イオン）が移動しないため、繰返し充放電しても金属極が安定するという利点を有する。前記金属は、充電−放電状態により、その一部または全部が、金属（例えばＦｅ）または金属酸化物（例えばＦｅ2Ｏ3）の状態をとる。 Examples of the metal used for the metal electrode include zinc, aluminum, lithium, iron, and magnesium. Among them, iron, aluminum, and magnesium are preferable. Magnesium is an abundant element unlike lithium and the like, and an improvement in battery voltage can be expected. Moreover, the said iron is meant to include iron alloys and iron-containing substances. Although the absolute value of the oxidation-reduction potential is relatively small, iron has an advantage that the metal electrode is stabilized even when repeatedly charged and discharged because the ionized product (iron ion) does not move. A part or all of the metal is in a metal (eg, Fe) or metal oxide (eg, Fe 2 O 3 ) state depending on a charge-discharge state.
上記電池における金属極の厚みは、例えば１ｎｍ以上であり、負極として十分に作用させるには０．１ｍｍ以上が好ましい。一方、金属極の厚みが厚くなりすぎると、電解質との良好な接触が困難となり有効に負極材料が利用できない、または素子の軽量・薄肉化が難しくなるという不具合が生じる。よって金属極の厚みは、３ｍｍ以下とすることが好ましく、より好ましくは１ｍｍ以下、さらに好ましくは１００μｍ未満である。 The thickness of the metal electrode in the said battery is 1 nm or more, for example, and 0.1 mm or more is preferable in order to fully function as a negative electrode. On the other hand, if the thickness of the metal electrode is too thick, it is difficult to make good contact with the electrolyte, and the negative electrode material cannot be used effectively, or it is difficult to reduce the weight and thickness of the element. Therefore, the thickness of the metal electrode is preferably 3 mm or less, more preferably 1 mm or less, and still more preferably less than 100 μm.
金属極は、金属箔であっても良いし、例えば平均粒径が０．０１〜１０μｍ（より好ましくは平均粒径が０．１〜５μｍ）である金属粉と金属ウール（例えば繊維径が１０〜６０μｍ）をペレット状に成形したものから構成されていても良い。 The metal electrode may be a metal foil, for example, metal powder having an average particle diameter of 0.01 to 10 μm (more preferably an average particle diameter of 0.1 to 5 μm) and metal wool (for example, a fiber diameter of 10 ˜60 μm) may be formed into a pellet shape.
金属極は、上記態様Ｂに示す通り、前記金属の他に、導体（例えばカーボン、カーボン合金、炭化物など）と、本発明の固体電解質材料（第２の固体電解質）とを含んだもの（以下「混合体」ということがある）が好ましい（特には、上記金属、導体および本発明の固体電解質材料からなる混合体が好ましい）。 As shown in the above-mentioned aspect B, the metal electrode includes a conductor (for example, carbon, carbon alloy, carbide, etc.) and the solid electrolyte material of the present invention (second solid electrolyte) in addition to the metal (hereinafter referred to as “the following”). “Sometimes referred to as“ mixture ”) is preferred (in particular, a mixture comprising the metal, conductor and solid electrolyte material of the present invention is preferred).
上記の通り金属極に導体が含まれることによって、金属極の金属が不動態化することによる電池のセル抵抗の上昇を軽減できる。特に前記金属が鉄、アルミニウム（特に鉄）である場合にその効果が顕著に発揮される。また、金属極に固体電解質（第２の固体電解質）が含まれることにより、金属の酸化によって生成する電子や、水酸化物イオンからの電子の授受を効率的に行うことができる。 By including a conductor in the metal electrode as described above, it is possible to reduce an increase in the cell resistance of the battery due to passivation of the metal of the metal electrode. In particular, when the metal is iron or aluminum (particularly iron), the effect is remarkably exhibited. Further, since the solid electrolyte (second solid electrolyte) is included in the metal electrode, electrons generated by metal oxidation and electrons from hydroxide ions can be efficiently exchanged.
金属極が、金属と導体と第２の固体電解質とを含む場合、これらの相互の位置関係及び濃度分布は特に限定されない。位置関係については、例えば金属と導体と第２の固体電解質の全てが混合された状態でも良いし、任意の順番で層状に並んでいても良い。前記混合された状態は、金属、導体および第２の固体電解質のいずれもが粉末であって、これらの混合粉末（混合方法は、一般的な方法を採用できる）を用いて形成したり、下記に示す通り、粉末状固体電解質に金属が部分的または連続的にコーティングされたものを用いたり、導体に金属が担持されたものを用いて形成してもよい。また濃度分布については、金属、導体、第２の固体電解質のそれぞれについて金属極中で均一であっても良いし、不均一であっても良い。 When the metal electrode includes a metal, a conductor, and a second solid electrolyte, their mutual positional relationship and concentration distribution are not particularly limited. Regarding the positional relationship, for example, the metal, the conductor, and the second solid electrolyte may all be mixed, or may be arranged in layers in an arbitrary order. The mixed state is formed by using any powder of the metal, the conductor, and the second solid electrolyte, and using a mixed powder thereof (a general method can be adopted), As shown in FIG. 5, the powdered solid electrolyte may be formed by partially or continuously coating a metal, or may be formed by using a metal supported on a conductor. The concentration distribution may be uniform in the metal electrode or non-uniform for each of the metal, the conductor, and the second solid electrolyte.
金属極として前記混合体を用いる場合、金属に対する導体の割合（導体／金属）は、質量比で０．０３／１〜０．３／１程度であり、金属に対する固体電解質の割合（固体電解質／金属）は、質量比で１／１〜１０／１程度である。 When the above mixture is used as the metal electrode, the ratio of the conductor to the metal (conductor / metal) is about 0.03 / 1 to 0.3 / 1 by mass ratio, and the ratio of the solid electrolyte to the metal (solid electrolyte / (Metal) is about 1/1 to 10/1 in mass ratio.
金属極における金属元素の含有割合は、例えば１５原子％以上であり、好ましくは２０原子％以上、より好ましくは３０原子％以上であり、１００原子％であっても良い。 The content ratio of the metal element in the metal electrode is, for example, 15 atomic% or more, preferably 20 atomic% or more, more preferably 30 atomic% or more, and may be 100 atomic%.
また金属極は、固体電解質（上記態様Ａにおける第１の固体電解質、上記態様Ｂ（即ち、第１及び第２の固体電解質を含む場合）における第２の固体電解質）の表面に直接形成されることも好ましい。固体電解質を用いた電池では、電極材料と電解質材料との界面部分の抵抗が大きく、特性を悪化させることが知られている。また、電池材料に粉末状の物質を用いた場合、電池は、それぞれのエレメント（電極材料、電解質材料）を混合し、圧力を加えて形成するが、該方法ではエレメント同士の接触が十分ではなく、電池の特性が十分に発揮できない恐れがある。よって金属極を、固体電解質材料表面に直接接触するように形成することで、金属極と電解質との間の抵抗を下げて特性を向上できる。 The metal electrode is directly formed on the surface of the solid electrolyte (the first solid electrolyte in the above-described aspect A, the second solid electrolyte in the above-described aspect B (that is, the case where the first and second solid electrolytes are included)). It is also preferable. In a battery using a solid electrolyte, it is known that the resistance at the interface between the electrode material and the electrolyte material is large and the characteristics are deteriorated. In addition, when a powdery substance is used as the battery material, the battery is formed by mixing each element (electrode material, electrolyte material) and applying pressure, but this method does not provide sufficient contact between the elements. The battery characteristics may not be fully exhibited. Therefore, by forming the metal electrode so as to be in direct contact with the surface of the solid electrolyte material, the resistance between the metal electrode and the electrolyte can be lowered to improve the characteristics.
前記直接形成する態様には、金属が第２の固体電解質の表面に、部分的に形成される場合と、連続的に形成される場合とがある。 There are cases where the metal is partially formed on the surface of the second solid electrolyte and a case where the metal is continuously formed.
好ましくは、金属が第２の固体電解質の各粒子表面に直接かつ部分的に（不連続に）形成された態様である。金属極が、上記表面に直接かつ部分的に金属の形成された第２の固体電解質（粒子）と、導体粉末（例えばカーボンを主成分とする導体粉末）との混合体であり、この金属極と、第１の固体電解質（金属は形成されていない）と、空気極とがこの順に備えられた電池が好ましい。この様な構成の電池であれば、空気極側から導入された水酸化物イオンが、金属の不連続部分から進入して該金属（例えば鉄）と反応し、導電体に電子を効率よく受け渡すことが可能となり、利用効率の高い電池が実現できる。 Preferably, the metal is formed directly and partially (discontinuously) on the surface of each particle of the second solid electrolyte. The metal electrode is a mixture of a second solid electrolyte (particle) in which a metal is formed directly and partially on the surface, and a conductor powder (for example, a conductor powder containing carbon as a main component). A battery in which the first solid electrolyte (no metal is formed) and the air electrode are provided in this order is preferable. In a battery having such a configuration, hydroxide ions introduced from the air electrode side enter from a discontinuous portion of the metal and react with the metal (for example, iron), and efficiently receive electrons in the conductor. It is possible to deliver a battery with high utilization efficiency.
金属が第２の固体電解質の各粒子表面に直接かつ部分的に形成される場合、固体電解質の各粒子表面の金属の被覆率は５０％以上であることが好ましい。またこの場合、固体電解質の各粒子表面に形成する金属の厚さは、１ｎｍ以上が好ましい。金属の厚さが薄すぎると、金属が固体電解質の凹凸部分に入って金属表面への金属、固体電解質、炭素との接触ができず、電気が流れない。一方、上記金属の厚さが厚すぎると、反応に寄与しない金属の割合が増え、効率が低下する。金属の厚さの上限は、固体電解質（例えば粉末）の形状がほぼ金属付着前の状態を保っていれば良く、例えば固体電解質粉末の粒径の１／１０程度であり、通常は１μｍ以下である。 When the metal is directly and partially formed on each particle surface of the second solid electrolyte, the metal coverage on each particle surface of the solid electrolyte is preferably 50% or more. In this case, the thickness of the metal formed on the surface of each particle of the solid electrolyte is preferably 1 nm or more. If the thickness of the metal is too thin, the metal enters the uneven portion of the solid electrolyte and cannot contact the metal, solid electrolyte, or carbon on the metal surface, and electricity does not flow. On the other hand, if the thickness of the metal is too thick, the proportion of the metal that does not contribute to the reaction increases and the efficiency decreases. The upper limit of the thickness of the metal is sufficient if the shape of the solid electrolyte (for example, the powder) is substantially in a state before adhesion of the metal, for example, about 1/10 of the particle diameter of the solid electrolyte powder, and is usually 1 μm or less. is there.
金属が固体電解質の各粒子表面に部分的に形成されている上記態様には、金属が凝集して形成されているような場合も含み、部分的に形成されている場合の金属の厚さとは、連続膜に換算した膜厚を意味する。 The above-described embodiment in which the metal is partially formed on the surface of each particle of the solid electrolyte includes the case where the metal is aggregated and formed. What is the thickness of the metal in the case where the metal is partially formed? It means the film thickness converted into a continuous film.
一方、金属を固体電解質材料表面に直接かつ連続的に形成する場合には、該金属の厚みは、１ｎｍ以上、１００μｍ未満であることが好ましく（より好ましくは３ｎｍ以上、１μｍ以下）、かつ金属極中のＦｅ濃度が３０原子％以上であることが好ましい。金属の厚みが１ｎｍ未満となると、固体電解質上の金属極の被覆性が極端に低下するため、電極層としての性能が十分に発揮できない。一方、金属の厚みが１００μｍ以上となると、金属極自体の質量が電池質量の増加を招き、単位質量当たりの充電効率が低くなるため好ましくない。また、金属極中のＦｅ濃度を３０原子％以上とすれば、電池の単位重量当たりの放電容量が大きくすることができるため好ましい。尚、上記Ｆｅ濃度は、ＴＥＭのＥＤＸ分析の半定量分析の分析値から算出できる。 On the other hand, when the metal is directly and continuously formed on the surface of the solid electrolyte material, the thickness of the metal is preferably 1 nm or more and less than 100 μm (more preferably 3 nm or more and 1 μm or less), and the metal electrode The Fe concentration in the medium is preferably 30 atomic% or more. When the thickness of the metal is less than 1 nm, the coverage of the metal electrode on the solid electrolyte is extremely lowered, so that the performance as the electrode layer cannot be sufficiently exhibited. On the other hand, when the thickness of the metal is 100 μm or more, the mass of the metal electrode itself causes an increase in the mass of the battery, which is not preferable because the charging efficiency per unit mass is reduced. Moreover, it is preferable that the Fe concentration in the metal electrode is 30 atomic% or more because the discharge capacity per unit weight of the battery can be increased. The Fe concentration can be calculated from the analysis value of semi-quantitative analysis of EDX analysis of TEM.
前記固体電解質材料表面に金属極を直接形成する方法として、例えばＰＶＤ法（例えばスパッタリング法、真空蒸着法）が挙げられる。 As a method for directly forming a metal electrode on the surface of the solid electrolyte material, for example, a PVD method (for example, a sputtering method or a vacuum deposition method) can be cited.
前記混合体において、前記導体と前記金属の形成された第２の固体電解質との混合比は、前記金属の形成された第２の固体電解質の割合が、空気極側に近づくにつれて多くなるようにすると、金属極の電子の取出しがスムーズに行われるので好ましい。 In the mixture, the mixing ratio between the conductor and the second solid electrolyte formed with the metal is such that the ratio of the second solid electrolyte formed with the metal increases toward the air electrode side. Then, since the taking-out of the electron of a metal electrode is performed smoothly, it is preferable.
また金属極が、金属と導体と第２の固体電解質とを含む態様において、金属を導体に担持させることも好ましい。金属を導体に担持させることで、ナノサイズの金属を形成することができ、反応に寄与する表面積を増やすことができる。特には、前記金属が鉄、前記導体がカーボンであり、且つカーボンに鉄が担持されていることが好ましい。 In the aspect in which the metal electrode includes a metal, a conductor, and a second solid electrolyte, it is also preferable that the metal be supported on the conductor. By supporting the metal on the conductor, a nano-sized metal can be formed, and the surface area contributing to the reaction can be increased. In particular, it is preferable that the metal is iron, the conductor is carbon, and iron is supported on the carbon.
次に本発明の金属−空気全固体二次電池における空気極について詳述する。該空気極は、金属−空気全固体二次電池の正極として作用するものであり、下記（２）式の反応が生じている。
Ｏ2 ＋ Ｈ2Ｏ ＋ ４ｅ- → ４ＯＨ- …（２）
Next, the air electrode in the metal-air all-solid secondary battery of the present invention will be described in detail. The air electrode functions as a positive electrode of the metal-air all solid secondary battery, and a reaction of the following formula (2) occurs.
O 2 + H 2 O + 4e − → 4OH − (2)
本発明における空気極は、炭素と酸素還元触媒を含むものである。例えば空気極として触媒付きカーボン層を用いることができる。前記触媒は、酸素の還元反応を促進できるものであればよく、例えばＰｔやＭｎＯ2などが挙げられる。前記カーボン層の形態は、炭素粉末の圧粉体であっても良いし、カーボンペーパーなどを用いても良い。 The air electrode in the present invention contains carbon and an oxygen reduction catalyst. For example, a carbon layer with a catalyst can be used as the air electrode. The catalyst may be any catalyst that can promote the oxygen reduction reaction, and examples thereof include Pt and MnO 2 . The form of the carbon layer may be a green compact of carbon powder, or carbon paper or the like may be used.
上記空気極を正極として十分に機能させるため、空気極の厚みは０．０５ｍｍ以上が好ましく、より好ましくは０．１ｍｍ以上である。一方、空気極（例えば、触媒付きカーボン層）の厚みが厚くなりすぎると、電解質／触媒／空気の三相界面を効率良く形成することが困難となる。よって、空気極（正極）の厚みは０．３ｍｍ以下とすることが好ましく、より好ましくは０．２ｍｍ以下である。 In order for the air electrode to function sufficiently as a positive electrode, the thickness of the air electrode is preferably 0.05 mm or more, and more preferably 0.1 mm or more. On the other hand, if the thickness of the air electrode (for example, the carbon layer with catalyst) becomes too thick, it becomes difficult to efficiently form the three-phase interface of electrolyte / catalyst / air. Therefore, the thickness of the air electrode (positive electrode) is preferably 0.3 mm or less, more preferably 0.2 mm or less.
金属−空気全固体二次電池は、上記の固体電解質層の一方側に炭素と酸素還元触媒を含む空気極、他方側に金属を含む金属極を積層し、室温〜５００℃、５００ＭＰａ以下、１〜１００分の条件下でプレスすることによって製造することができる。また、固体電解質層と空気極、また固体電解質層と金属極は、これらの間に密着性を向上させるためのプライマー層を設けても良い。 The metal-air all solid state secondary battery is formed by laminating an air electrode containing carbon and an oxygen reduction catalyst on one side of the solid electrolyte layer and a metal electrode containing a metal on the other side, and having a room temperature to 500 ° C., 500 MPa or less, 1 It can manufacture by pressing on the conditions for -100 minutes. In addition, the solid electrolyte layer and the air electrode, or the solid electrolyte layer and the metal electrode may be provided with a primer layer for improving adhesion.
以下、実施例を挙げて本発明をより具体的に説明する。本発明は以下の実施例によって制限を受けるものではなく、前記、後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも勿論可能であり、それらはいずれも本発明の技術的範囲に包含される。 Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited by the following examples, and can of course be implemented with appropriate modifications within a range that can be adapted to the above-described gist. Included in the range.
［実施例１］
固体電解質材料の作製は、図１に示す手順で行った。まず、層状水酸化物であるハイドロタルサイト（以下、「ＬＤＨ」という場合がある）粉末と水酸化カリウム水溶液との混合液を室温で３０分間撹拌して、ゲル化物（中間ゲル化物）を得た。前記ＬＤＨに対する水酸化カリウムのモル比（ｘ）は、０，０．５，１，１．５，２とした。上記ゲル化物（中間ゲル化物）を６０℃で２日間放置し、固体電解質材料として、水酸化カリウムとハイドロタルサイトの複合体（以下、「ＫＯＨ／ＬＤＨ複合体」という）の粉末を形成した。
[Example 1]
The production of the solid electrolyte material was performed according to the procedure shown in FIG. First, a mixture of a hydrotalcite (hereinafter sometimes referred to as “LDH”) powder that is a layered hydroxide and an aqueous potassium hydroxide solution is stirred at room temperature for 30 minutes to obtain a gelled product (intermediate gelled product). It was. The molar ratio (x) of potassium hydroxide to LDH was 0, 0.5, 1, 1.5, 2. The gelled product (intermediate gelled product) was left at 60 ° C. for 2 days to form a powder of a complex of potassium hydroxide and hydrotalcite (hereinafter referred to as “KOH / LDH complex”) as a solid electrolyte material.
得られたＫＯＨ／ＬＤＨ複合体のイオン導電率（交流導電率）は、次の様にして測定した。即ち、金型（島津製作所、ＫＢｒ錠剤成形器）を用い、前記ＫＯＨ／ＬＤＨ複合体粉末を、カーボンペーパー（直径１３ｍｍ、厚み０．２ｍｍ程度）で挟んだ状態で、５ＭＰａ、１０ｍｉｎの条件下で圧着させることにより、ペレット状（直径１３ｍｍ、厚み０．４〜０．８ｍｍ）、かつ電極の接合された試料を得た。この試料を用い、電気化学測定システム（ＳＩ １２６０、Ｓｏｌａｒｔｒｏｎ社）、および専用のソフトウェア（Ｚ−ｐｌｏｔ）を用い、ＫＯＨ／ＬＤＨ複合体の３０〜８０℃の種々の温度でのイオン導電率（交流導電率）を測定した。その結果を図２に示す。 The ionic conductivity (AC conductivity) of the obtained KOH / LDH composite was measured as follows. That is, using a mold (Shimadzu Corporation, KBr tablet molding machine), the KOH / LDH composite powder was sandwiched between carbon papers (diameter 13 mm, thickness 0.2 mm) under the conditions of 5 MPa and 10 min. By pressure bonding, a sample in the form of pellets (diameter 13 mm, thickness 0.4 to 0.8 mm) and electrodes joined thereto was obtained. Using this sample, using an electrochemical measurement system (SI 1260, Solartron) and dedicated software (Z-plot), the ionic conductivity (alternating current) of KOH / LDH complex at various temperatures of 30 to 80 ° C. Conductivity) was measured. The result is shown in FIG.
図２は、ＬＤＨに対する水酸化カリウムのモル比ｘを０、０．５、１、１．５、２と変化させたときの、ＫＯＨ／ＬＤＨ複合体の交流導電率を示したグラフである（なお、縦軸は交流導電率の常用対数で表す）。この図２より、ＬＤＨに対する水酸化カリウムのモル比（ｘ）が１以上で良好な伝導性が得られることが分かった。即ち、図２によれば、水酸化カリウムを含む本発明の固体電解質材料を電極に用いた場合、室温付近でも１０-3Ｓ／ｃｍ程度の高い導電率を達成できることが分かった。 FIG. 2 is a graph showing the AC conductivity of the KOH / LDH composite when the molar ratio x of potassium hydroxide to LDH is changed to 0, 0.5, 1, 1.5, and 2 ( The vertical axis represents the common logarithm of AC conductivity). From FIG. 2, it was found that good conductivity can be obtained when the molar ratio (x) of potassium hydroxide to LDH is 1 or more. That is, according to FIG. 2, it was found that when the solid electrolyte material of the present invention containing potassium hydroxide was used as an electrode, a high conductivity of about 10 −3 S / cm could be achieved even near room temperature.
［実施例２］
実施例１で得られた固体電解質材料を用い、金属−空気全固体二次電池を作製した。
[Example 2]
Using the solid electrolyte material obtained in Example 1, a metal-air all solid secondary battery was produced.
金属極には、スポンジ状鉄０．２ｇ（和光純薬工業株式会社製、鉄粉の平均粒径：１〜５μｍ）を使用した。空気極には、触媒付きカーボン層として、ケミックス社製のカーボンペーパーに触媒として、ＭｎＯ2（５〜１０ｍｇ／ｃｍ2）を担持させたものをそれぞれ用意した。そして図３に概略的に示す通り、スポンジ状鉄３、ＬＤＨに対する水酸化カリウムのモル比（ｘ）が種々のＫＯＨ／ＬＤＨ複合体粉末２、触媒付きカーボンペーパー１を順に積層し、室温、２００ＭＰａで３分間プレスして直径（φ）１３ｍｍの円柱状電池を作製した。該電池における各層の厚みは、金属極（スポンジ状鉄を使用）：０．２ｍｍ、固体電解質（ＫＯＨ／ＬＤＨ複合体粉末を使用）：０．３ｍｍ、空気極（触媒付きカーボンペーパーを使用）：０．１ｍｍとした。 For the metal electrode, 0.2 g of sponge iron (manufactured by Wako Pure Chemical Industries, Ltd., average particle size of iron powder: 1 to 5 μm) was used. In the air electrode, a carbon layer with a catalyst and a carbon paper made by Chemix Co., Ltd., carrying MnO 2 (5 to 10 mg / cm 2 ) as a catalyst were prepared. Then, as schematically shown in FIG. 3, sponge iron 3, KOH / LDH composite powder 2 having various molar ratios (x) of potassium hydroxide to LDH, and carbon paper 1 with catalyst are sequentially laminated, and room temperature, 200 MPa. Was pressed for 3 minutes to produce a cylindrical battery having a diameter (φ) of 13 mm. The thickness of each layer in the battery is as follows: metal electrode (using sponge iron): 0.2 mm, solid electrolyte (using KOH / LDH composite powder): 0.3 mm, air electrode (using carbon paper with catalyst): It was set to 0.1 mm.
前記モル比ｘが種々の各電池について、高性能ポテンショスタット／ガルバノスタット（Ｓｏｌａｒｔｒｏｎ、ＳＩ １２８７、ＤＣ分極電圧：±１４．５Ｖ（±１４．５Ｖに対しての分解能１００μＶ）、電流：±２Ａ（分解能１００ｐＡ）、測定分解能（装置の解析理論限界）［電流分解能：１ｐＡ、電圧分解能：1μＶ］）、および周波数応答アナライザ（Ｓｏｌａｒｔｒｏｎ、１２５２Ａ、周波数範囲：１０ｋＨｚ〜３００ｋＨｚ、交流振幅：０〜３Ｖｒｍｓ、交流振幅分解能：５ｍＶ）を用いて、セル電圧と電流密度を測定した。その結果を図４に示す。 For each battery having various molar ratios x, a high performance potentiostat / galvanostat (Solartron, SI 1287, DC polarization voltage: ± 14.5 V (resolution of 100 μV with respect to ± 14.5 V), current: ± 2 A ( Resolution 100 pA), measurement resolution (analysis theoretical limit of the apparatus) [current resolution: 1 pA, voltage resolution: 1 μV]), and frequency response analyzer (Solartron, 1252A, frequency range: 10 kHz to 300 kHz, AC amplitude: 0 to 3 Vrms, AC Amplitude resolution: 5 mV) was used to measure cell voltage and current density. The result is shown in FIG.
図４によれば、ＫＯＨ／ＬＤＨ複合体の、ＬＤＨに対する水酸化カリウムのモル比（ｘ）が２のときに、最も大きな電流が得られることが分かった。 According to FIG. 4, when the molar ratio (x) of potassium hydroxide to LDH in the KOH / LDH composite was 2, it was found that the largest current was obtained.
［実施例３］
実施例１と同様の方法で、ＬＤＨに対する水酸化カリウムのモル比（ｘ）が種々のＫＯＨ／ＬＤＨ複合体粉末を形成した。そして該粉末を用い、ＫＯＨ／ＬＤＨ複合体の構造をＸＲＤ（Ｘ線回折）で解析した。その結果を図５に示す。
[Example 3]
In the same manner as in Example 1, KOH / LDH composite powders having various molar ratios (x) of potassium hydroxide to LDH were formed. And using this powder, the structure of the KOH / LDH complex was analyzed by XRD (X-ray diffraction). The result is shown in FIG.
図５に示されたＸ線回折スペクトルから、本発明のＫＯＨ／ＬＤＨ複合体では、ＫＯＨが単体で存在しておらず、ＫＯＨがＫ+とＯＨ-に解離し、ＬＤＨの層間もしくは表面にイオンの状態で分散、複合化されていることがわかった。 From the X-ray diffraction spectrum shown in FIG. 5, in the KOH / LDH composite of the present invention, KOH does not exist alone, KOH dissociates into K + and OH − , and ions are present between the layers or the surface of LDH. It was found that they were dispersed and compounded in this state.
［実施例４］
実施例１の電解質（ＬＤＨに対する水酸化カリウムのモル比ｘ＝２）を用い、金属極の種類を変えて二次電池の評価を行った。
[Example 4]
The secondary battery was evaluated using the electrolyte of Example 1 (molar ratio of potassium hydroxide to LDH x = 2) and changing the type of metal electrode.
金属極に、スポンジ状鉄を使用した試料（電池ａ）は、実施例２の通り作製した。また、別の試料（電池ｂ）として、金属極に、純鉄粉、電解質粉末およびカーボン粉末（混合割合は、質量比で、純鉄粉：電解質粉末（ＫＯＨ／ＬＤＨ複合体粉末）：カーボン粉末＝１：１〜１０：０．０３〜０．２４）からなる混合粉末を用いた（金属極をコンポジット電極とした）こと以外は実施例２と同様にして、金属−空気全固体二次電池を作製した。 A sample (battery a) using sponge-like iron for the metal electrode was prepared as in Example 2. As another sample (battery b), pure iron powder, electrolyte powder, and carbon powder (mixing ratio is a mass ratio, pure iron powder: electrolyte powder (KOH / LDH composite powder): carbon powder as a metal electrode. = 1: 1 to 10: 0.03 to 0.24), except that a mixed powder was used (the metal electrode was a composite electrode). Was made.
そして、各電池を、実施例２と同様に高性能ポテンショスタット／ガルバノスタットを用いて測定し、電圧と電流密度の関係を調べた。その結果を図６に示す。 Each battery was measured using a high performance potentiostat / galvanostat in the same manner as in Example 2, and the relationship between voltage and current density was examined. The result is shown in FIG.
図６より次のことがわかる。金属極に前記混合粉末を用いた電池ｂ（図６中の（ｂ））は、金属極に鉄のみを用いた電池ａ（図６中の（ａ））に比べて高い性能を示した。金属極にカーボンを含有させることによって、電子伝導パスが形成され、鉄の不動態化によるセル抵抗の上昇が軽減されたため、性能が向上したと考えられる。また、充放電試験も行った結果、金属極に前記混合粉末を用いた電池は、充放電も可能であることが分かった。 The following can be seen from FIG. Battery b using the mixed powder for the metal electrode ((b) in FIG. 6) showed higher performance than battery a using only iron for the metal electrode ((a) in FIG. 6). By including carbon in the metal electrode, an electron conduction path was formed, and the increase in cell resistance due to the passivation of iron was reduced. Moreover, as a result of conducting a charge / discharge test, it was found that the battery using the mixed powder for the metal electrode can also be charged / discharged.
１ 触媒付きカーボンペーパー
２ ＫＯＨ／ＬＤＨ複合体粉末
３ スポンジ状鉄
1 Carbon paper with catalyst 2 KOH / LDH composite powder 3 Sponge-like iron
Claims (4)
前記第１の固体電解質が、請求項１または２に記載の固体電解質材料からなることを特徴とする金属−空気全固体二次電池。 A metal-air all-solid secondary battery comprising an air electrode including carbon and an oxygen reduction catalyst, a metal electrode including a metal, and a first solid electrolyte,
3. The metal-air all-solid secondary battery, wherein the first solid electrolyte is made of the solid electrolyte material according to claim 1 or 2.
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| JP2016219248A (en) * | 2015-05-20 | 2016-12-22 | 株式会社日本触媒 | Air metal battery |
| CN108110316A (en) * | 2017-12-29 | 2018-06-01 | 成都新柯力化工科技有限公司 | A kind of lithium battery polymer dielectric and preparation method with the accumulation of neatly rock layers |
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