JP2020021609A - Aqueous solution secondary battery - Google Patents

Aqueous solution secondary battery Download PDF

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JP2020021609A
JP2020021609A JP2018144139A JP2018144139A JP2020021609A JP 2020021609 A JP2020021609 A JP 2020021609A JP 2018144139 A JP2018144139 A JP 2018144139A JP 2018144139 A JP2018144139 A JP 2018144139A JP 2020021609 A JP2020021609 A JP 2020021609A
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negative electrode
positive electrode
secondary battery
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conductive material
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JP6863347B2 (en
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志賀　亨
Toru Shiga
亨 志賀
長谷　陽子
Yoko Hase
陽子 長谷
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Toyota Central R&D Labs Inc
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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
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Abstract

To further improve charge/discharge characteristics of an aqueous solution secondary battery.SOLUTION: An aqueous solution secondary battery of the present disclosure includes: a positive electrode having a positive electrode active material; a negative electrode having an oxidation-reduction potential within the range of 1.2 V or more and 2.5 V or less at Li reference potential, including one or more of Nb, Ru and Ti as a negative electrode active material, and containing powder of one or more of Zn, Al, Mg, Si, Sn and TaB as a conductive material; and an aqueous solution electrolyte conducting alkali metal ions between the positive electrode and the negative electrode.SELECTED DRAWING: Figure 3

Description

本明細書では、水溶液系二次電池を開示する。   In this specification, an aqueous secondary battery is disclosed.

従来、蓄電デバイスとして用いられるＬｉイオン電池の課題の一つとして、電解液の不燃化が挙げられる。この課題に対して、水溶液を電解液とする二次電池が開発されている。近年、水溶液系二次電池において、作動電圧が２．０Ｖを超えるものが提案されている（例えば、非特許文献１，２参照）。非特許文献１には、正極活物質をＬｉＭｎ2Ｏ4、負極活物質をＭｏ6Ｓ8とし、Ｌｉ（ＣＦ3ＳＯ2）2Ｎ（ＬｉＴＦＳＡ）を高濃度に溶解した電解液を用いており、作動電圧２．１Ｖを示すとしている。また、非特許文献２には、正極活物質をＬｉＮｉ0.5Ｍｎ1.5Ｏ4、負極活物質をＬｉ4Ｔｉ5Ｏ12とし、ＬｉＴＦＳＡとＬｉ（Ｃ2Ｆ5ＳＯ2）2Ｎ（ＬｉＢＥＴＩ）とを３：１で高濃度に溶解した電解液を用いており、作動電圧３．０Ｖを示すとしている。 2. Description of the Related Art Conventionally, one of the problems of a Li-ion battery used as a power storage device is to make an electrolyte non-flammable. To address this problem, secondary batteries using an aqueous solution as an electrolyte have been developed. In recent years, an aqueous secondary battery having an operating voltage exceeding 2.0 V has been proposed (for example, see Non-Patent Documents 1 and 2). Non-Patent Document 1 uses an electrolyte in which LiMn 2 O 4 is used as a positive electrode active material, Mo 6 S 8 is used as a negative electrode active material, and Li (CF 3 SO 2 ) 2 N (LiTFSA) is dissolved at a high concentration. , Operating voltage 2.1V. In addition, Non-Patent Document 2 discloses that the positive electrode active material is LiNi 0.5 Mn 1.5 O 4 , the negative electrode active material is Li 4 Ti 5 O 12, and LiTFSA and Li (C 2 F 5 SO 2 ) 2 N (LiBETI) are used. It uses an electrolytic solution dissolved at a high concentration of 3: 1 and exhibits an operating voltage of 3.0 V.

Science 20 Nov 2015:Vol.350,Issue6263,pp.938-943Science 20 Nov 2015: Vol.350, Issue6263, pp.938-943 Nature Energy 1, Article number: 16129 (2016)Nature Energy 1, Article number: 16129 (2016)

ところで、水溶液系二次電池では、ＬｉＴＦＳＡの水溶液は、電極の構成によっては充放電の電位により電気分解することがあり、キャリアとなるイオン（例えば、Ｌｉイオン）が消費されてしまうことがあった。このため、水溶液系二次電池では、放電容量が小さくなることがあった。   By the way, in the aqueous secondary battery, the aqueous solution of LiTFSA may be electrolyzed depending on the charge / discharge potential depending on the electrode configuration, and the ions serving as carriers (for example, Li ions) may be consumed. . For this reason, in the aqueous secondary battery, the discharge capacity was sometimes small.

本開示は、このような課題に鑑みなされたものであり、充放電特性をより向上した水溶液系二次電池を提供することを主目的とする。   The present disclosure has been made in view of such a problem, and has as its main object to provide an aqueous secondary battery with further improved charge / discharge characteristics.

上述した目的を達成するために鋭意研究したところ、本発明者らは、特定の金属粉や化合物粉を導電材として負極に添加すると、充放電特性をより向上することができることを見いだし、本明細書で開示する発明を完成するに至った。   The present inventors have conducted intensive studies to achieve the above-described object, and as a result, the present inventors have found that when a specific metal powder or compound powder is added to a negative electrode as a conductive material, the charge-discharge characteristics can be further improved. The invention disclosed in this document has been completed.

即ち、本明細書で開示する水溶液系二次電池は、
正極活物質を有する正極と、
Ｌｉ基準電位で１．２Ｖ以上２．５Ｖ以下の範囲内に酸化還元電位を有しＮｂ、Ｒｕ及びＴｉのうち１以上を含む金属酸化物を負極活物質として有し、導電材としてのＺｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を含む負極と、
前記正極と前記負極との間でアルカリ金属イオンを伝導する水溶液系電解液と、
を備えたものである。 That is, the aqueous secondary battery disclosed herein is:
A positive electrode having a positive electrode active material,
A metal oxide having a redox potential within a range of 1.2 V or more and 2.5 V or less at a Li reference potential and containing one or more of Nb, Ru, and Ti as a negative electrode active material; Zn as a conductive material; A negative electrode containing at least one powder of Al, Mg, Si, Sn, and TaB;
An aqueous electrolyte solution that conducts alkali metal ions between the positive electrode and the negative electrode,
It is provided with.

本開示は、放電容量をより向上するなど、充放電特性をより向上する水溶液系二次電池を提供することができる。このような効果が得られる理由は、例えば、以下のように考えられる。この水溶液系二次電池では、特定の粉体を導電材として含む。一般的に、水溶液系二次電池では、集電体としてＡｌ箔を用い、導電材としてカーボン系の材料、例えば、カーボンブラックなどを用いる。図１は、水の還元電位と充放電曲線との一例の関係図である。図１では、Ａｌを添加したリチウムマンガン複合酸化物を正極活物質とし、ニオブ酸化物を負極活物質に用いた一例を示す。図２は、水溶液系二次電池に用いられる材料の電位と電流密度との一例の関係図である。図２では、電解液としてマグネシウムビス（トリフルオロメタンスルホニル）アミド（ＭｇＴＦＳＡ）を３．４８ｍｏｌ％添加したものを用いた一例を示す。図１に示すように、水溶液系二次電池では、放電電位が水の還元電位を下回ると水が還元分解されキャリアであるＬｉイオンが消費される。このため、充放電サイクルを行うと、数回のサイクルで大きな放電容量の低下が起きる。このキャリアの消費は、負極に含まれるカーボン上で起きると推察される（図２参照）。本開示の水溶液系二次電池では、導電材として、Ｚｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を用いることにより、これらの粉体が導電性を示すと共に、水溶液の還元分解をより抑制することができるものと推察される。このため、この水溶液系二次電池では、充電容量と放電容量との差がより小さく、且つ放電容量を飛躍的に増大することができるものと推察される。   The present disclosure can provide an aqueous secondary battery in which the charge and discharge characteristics are further improved, such as by further improving the discharge capacity. The reason why such an effect is obtained is considered, for example, as follows. This aqueous secondary battery contains a specific powder as a conductive material. Generally, in an aqueous secondary battery, an Al foil is used as a current collector, and a carbon-based material such as carbon black is used as a conductive material. FIG. 1 is a diagram illustrating an example of a relationship between a reduction potential of water and a charge / discharge curve. FIG. 1 illustrates an example in which a lithium-manganese composite oxide to which Al is added is used as a positive electrode active material and niobium oxide is used as a negative electrode active material. FIG. 2 is a diagram illustrating an example of the relationship between the potential and the current density of a material used for an aqueous secondary battery. FIG. 2 shows an example in which magnesium bis (trifluoromethanesulfonyl) amide (MgTFSA) to which 3.48 mol% is added is used as the electrolytic solution. As shown in FIG. 1, in the aqueous secondary battery, when the discharge potential is lower than the reduction potential of water, water is reductively decomposed and Li ions as carriers are consumed. Therefore, when a charge / discharge cycle is performed, a large reduction in discharge capacity occurs in several cycles. It is presumed that this carrier consumption occurs on carbon contained in the negative electrode (see FIG. 2). In the aqueous secondary battery of the present disclosure, by using one or more powders of Zn, Al, Mg, Si, Sn, and TaB as the conductive material, these powders exhibit conductivity, and It is presumed that reductive decomposition can be further suppressed. For this reason, it is presumed that in this aqueous secondary battery, the difference between the charge capacity and the discharge capacity is smaller, and the discharge capacity can be dramatically increased.

水の還元電位と充放電曲線との一例の関係図。FIG. 3 is a diagram illustrating an example of a relationship between a reduction potential of water and a charge / discharge curve. 電位と電流密度との関係図。FIG. 4 is a diagram showing the relationship between potential and current density. 水溶液系二次電池２０の一例を示す模式図。FIG. 2 is a schematic view showing an example of an aqueous secondary battery 20. 実験例１〜３の充放電曲線。9 is a charge / discharge curve of Experimental Examples 1 to 3. 実験例６の３サイクルまでの充放電曲線。9 is a charge / discharge curve of Experimental Example 6 up to three cycles. 実験例７、８の充放電曲線。9 is a charge / discharge curve of Experimental Examples 7 and 8. 実験例１１、１２の充放電曲線。13 is a charge / discharge curve of Experimental Examples 11 and 12. 実験例１５の充放電曲線。15 is a charge / discharge curve of Experimental Example 15. 実験例１７の充放電曲線。18 is a charge / discharge curve of Experimental Example 17. 実験例１８の充放電曲線。18 is a charge / discharge curve of Experimental Example 18. 実験例２４、２５の充放電曲線。25 is a charge / discharge curve of Experimental Examples 24 and 25.

本開示の水溶液系二次電池は、正極活物質を有する正極と、負極活物質を有する負極と、正極と負極との間に介在しアルカリ金属イオンを伝導する水溶液系電解液と、を備えている。ここで、この水溶液系二次電池のキャリアとなるアルカリ金属イオンは、例えば、リチウム、ナトリウム、カリウムなどのイオンが挙げられ、このうちリチウムやナトリウムのイオンが好ましい。負極は、Ｌｉ基準電位で１．２Ｖ以上２．５Ｖ以下の範囲内に酸化還元電位を有し、Ｎｂ、Ｒｕ及びＴｉのうち１以上を含む金属酸化物を負極活物質として有するものとする。また、負極には、Ｚｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を導電材として含むものとする。なお、以下では、説明の便宜のため、アルカリ金属イオンなど、アルカリ金属元素としてリチウムを主に説明する。   The aqueous secondary battery of the present disclosure includes a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and an aqueous solution electrolyte interposed between the positive electrode and the negative electrode and conducting alkali metal ions. I have. Here, examples of the alkali metal ion serving as a carrier of the aqueous secondary battery include ions such as lithium, sodium, and potassium. Of these, lithium and sodium ions are preferable. The negative electrode has an oxidation-reduction potential in a range of 1.2 V or more and 2.5 V or less as a Li reference potential, and has a metal oxide containing one or more of Nb, Ru, and Ti as a negative electrode active material. The negative electrode contains one or more powders of Zn, Al, Mg, Si, Sn, and TaB as a conductive material. In the following, for convenience of explanation, lithium is mainly described as an alkali metal element such as an alkali metal ion.

本開示の水溶液系二次電池の正極は、例えば正極活物質と導電材と結着材とを混合し、適当な溶剤を加えてペースト状の正極材としたものを、集電体の表面に塗布乾燥し、必要に応じて電極密度を高めるべく圧縮して形成してもよい。正極活物質としては、Ｌｉ基準電位で３．５Ｖ以上４．９Ｖ以下の範囲内に酸化還元電位を有するものを用いることが好ましい。このような正極活物質では、二次電池の電圧をより高めることができる。正極活物質は、例えば、Ｍｎを含み、更にＣｏ及びＮｉのうち１以上を含む遷移金属複合酸化物であるものとしてもよい。具体的には、基本組成式をＬｉ(1-x)ＭｎＯ2（０＜ｘ＜１など、以下同じ）やＬｉ(1-x)Ｍｎ2Ｏ4などとするリチウムマンガン複合酸化物、基本組成式をＬｉ(1-x)ＮｉaＭｎbＯ4（ａ＋ｂ＝２）などとするリチウムニッケルマンガン複合酸化物、基本組成式をＬｉ(1-x)ＮｉaＣｏbＭｎcＯ2（ａ＋ｂ＋ｃ＝１）などとするリチウムニッケルコバルトマンガン複合酸化物などを用いることができる。なお、「基本組成式」とは、他の元素（例えばＡｌやＭｇ、Ｃｒなど）を含んでもよい趣旨である。また、上記基本組成式のｘは１を超えてもよく、ａ＋ｂやａ＋ｂ＋ｃが１を超えるものとしてもよい。これらのうち、正極活物質は、ＬｉＭｎ2Ｏ4、ＬｉＡｌ0.1Ｍｎ1.9Ｏ4、ＬｉＣｒ0.1Ｍｎ1.9Ｏ4、ＬｉＮｉ0.5Ｍｎ1.5Ｏ4、ＬｉＮｉ1/3Ｃｏ1/3Ｍｎ1/3Ｏ2などが好ましい。 The positive electrode of the aqueous secondary battery of the present disclosure is, for example, a paste obtained by mixing a positive electrode active material, a conductive material and a binder, and adding an appropriate solvent to form a paste-like positive electrode material on the surface of the current collector. It may be formed by coating, drying, and, if necessary, compressing to increase the electrode density. It is preferable to use a positive electrode active material having an oxidation-reduction potential in a range of 3.5 V or more and 4.9 V or less as a Li reference potential. With such a positive electrode active material, the voltage of the secondary battery can be further increased. The positive electrode active material may be, for example, a transition metal composite oxide containing Mn and one or more of Co and Ni. Specifically, a lithium-manganese composite oxide having a basic composition formula of Li (1-x) MnO 2 (0 <x <1, etc., the same applies hereinafter), Li (1-x) Mn 2 O 4, etc. wherein the Li (1-x) Ni a Mn b O 4 (a + b = 2) lithium-nickel-manganese composite oxide, and the like, the basic compositional formula Li (1-x) Ni a Co b Mn c O 2 (a + b + c = The lithium nickel cobalt manganese composite oxide described in 1) and the like can be used. The “basic composition formula” is intended to include other elements (for example, Al, Mg, and Cr). Further, x in the above basic composition formula may exceed 1, and a + b or a + b + c may exceed 1. Among these, the positive electrode active materials include LiMn 2 O 4 , LiAl 0.1 Mn 1.9 O 4 , LiCr 0.1 Mn 1.9 O 4 , LiNi 0.5 Mn 1.5 O 4 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 and the like. Is preferred.

正極に用いられる導電材は、正極の電池性能に悪影響を及ぼさない電子伝導性材料であれば特に限定されず、例えば、天然黒鉛（鱗状黒鉛、鱗片状黒鉛）や人造黒鉛などの黒鉛、アセチレンブラック、カーボンブラック、ケッチェンブラック、カーボンウィスカ、ニードルコークス、炭素繊維、金属（銅、ニッケル、アルミニウム、銀、金など）などの１種又は２種以上を混合したものを用いることができる。これらの中で、導電材としては、電子伝導性及び塗工性の観点より、カーボンブラック及びアセチレンブラックが好ましい。結着材は、活物質粒子及び導電材粒子を繋ぎ止める役割を果たすものであり、例えば、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶｄＦ）、フッ素ゴム等の含フッ素樹脂、或いはポリプロピレン、ポリエチレン等の熱可塑性樹脂、エチレンプロピレンジエンモノマー（ＥＰＤＭ）ゴム、スルホン化ＥＰＤＭゴム、天然ブチルゴム（ＮＢＲ）等を単独で、あるいは２種以上の混合物として用いることができる。また、水系バインダーであるセルロース系やスチレンブタジエンゴム（ＳＢＲ）の水分散体等を用いることもできる。正極活物質、導電材、結着材を分散させる溶剤としては、例えばＮ−メチルピロリドン（ＮＭＰ）、ジメチルホルムアミド、ジメチルアセトアミド、メチルエチルケトン、シクロヘキサノン、酢酸メチル、アクリル酸メチル、ジエチレントリアミン、Ｎ，Ｎ−ジメチルアミノプロピルアミン、エチレンオキシド、テトラヒドロフランなどの有機溶剤を用いることができる。また、水に分散剤、増粘剤等を加え、ＳＢＲなどのラテックスで活物質をスラリー化してもよい。増粘剤としては、例えば、カルボキシメチルセルロース、メチルセルロースなどの多糖類を単独で、あるいは２種以上の混合物として用いることができる。導電材と結着材との比率は、導電材１００質量部に対し、結着材が３〜２５質量部であればよい。塗布方法としては、例えば、アプリケータロールなどのローラコーティング、スクリーンコーティング、ドクターブレイド方式、スピンコーティング、バーコータなどが挙げられ、これらのいずれかを用いて任意の厚さ・形状とすることができる。集電体としては、アルミニウム、チタン、ステンレス鋼、ニッケル、鉄、焼成炭素、導電性高分子、導電性ガラスなどのほか、接着性、導電性及び耐酸化性向上の目的で、アルミニウムや銅などの表面をカーボン、ニッケル、チタンや銀などで処理したものを用いることができる。これらについては、表面を酸化処理することも可能である。集電体の形状については、箔状、フィルム状、シート状、ネット状、パンチ又はエキスパンドされたもの、ラス体、多孔質体、発泡体、繊維群の形成体などが挙げられる。集電体の厚さは、例えば１〜５００μｍのものが用いられる。   The conductive material used for the positive electrode is not particularly limited as long as it is an electronic conductive material that does not adversely affect the battery performance of the positive electrode. For example, graphite such as natural graphite (flaky graphite, flaky graphite) and artificial graphite, and acetylene black , Carbon black, Ketjen black, carbon whiskers, needle coke, carbon fiber, and a mixture of two or more of metals (such as copper, nickel, aluminum, silver, and gold) can be used. Among these, carbon black and acetylene black are preferable as the conductive material from the viewpoints of electron conductivity and coatability. The binder plays a role of binding the active material particles and the conductive material particles. For example, a binder resin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), a fluorine-containing resin such as fluororubber, or polypropylene, Thermoplastic resins such as polyethylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM rubber, natural butyl rubber (NBR) and the like can be used alone or as a mixture of two or more. Further, an aqueous dispersion of a cellulose-based or styrene-butadiene rubber (SBR) as an aqueous binder can also be used. Examples of the solvent for dispersing the positive electrode active material, the conductive material, and the binder include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, and N, N-dimethyl. Organic solvents such as aminopropylamine, ethylene oxide, and tetrahydrofuran can be used. Further, a dispersant, a thickener, and the like may be added to water, and the active material may be slurried with a latex such as SBR. As the thickener, for example, polysaccharides such as carboxymethylcellulose and methylcellulose can be used alone or as a mixture of two or more. The ratio of the conductive material to the binder may be 3 to 25 parts by mass with respect to 100 parts by mass of the conductive material. Examples of the application method include roller coating such as an applicator roll, screen coating, a doctor blade method, spin coating, and a bar coater, and any of these can be used to obtain an arbitrary thickness and shape. Current collectors include aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, conductive glass, etc., and aluminum and copper for the purpose of improving adhesion, conductivity and oxidation resistance. The surface of which has been treated with carbon, nickel, titanium, silver or the like can be used. For these, the surface can be oxidized. Examples of the shape of the current collector include a foil shape, a film shape, a sheet shape, a net shape, a punched or expanded material, a lath body, a porous body, a foam, and a formed body of a fiber group. The thickness of the current collector is, for example, 1 to 500 μm.

本開示の水溶液系二次電池の負極は、負極活物質と集電体とを密着させて形成したものとしてもよいし、例えば負極活物質と結着材と必要に応じて導電材とを混合し、適当な溶剤を加えてペースト状の負極材としたものを、集電体の表面に塗布乾燥し、必要に応じて電極密度を高めるべく圧縮して形成してもよい。負極活物質は、Ｌｉ基準電位で１．２Ｖ以上２．５Ｖ以下の範囲内、より好ましくは１．５Ｖ以上２．５Ｖ以下の範囲内に酸化還元電位を有するものが好ましい。この範囲にある負極活物質では、水溶液系二次電池の電圧をより高めることができる。この負極活物質は、Ｎｂ、Ｒｕ及びＴｉのうち１以上を含む金属酸化物とすることができ、ニオブ酸化物、ルテニウム酸化物及びリチウムチタン複合酸化物のうち１以上とすることができる。具体的には、負極活物質は、Ｎｂ2Ｏ5、ＮｂＯ2、ＲｕＯ2及びＬｉ4Ｔｉ5Ｏ12のうち１以上であるものとしてもよい。負極に用いられる結着材、溶剤などは、それぞれ正極で例示したものを用いることができる。負極の集電体には、銅、ニッケル、ステンレス鋼、チタン、アルミニウム、焼成炭素、導電性高分子、導電性ガラス、Ａｌ−Ｃｄ合金などのほか、接着性、導電性及び耐還元性向上の目的で、例えば銅などの表面をカーボン、ニッケル、チタンや銀などで処理したものも用いることができる。これらについては、表面を酸化処理することも可能である。集電体の形状は、正極と同様のものを用いることができる。 The negative electrode of the aqueous secondary battery of the present disclosure may be formed by closely contacting a negative electrode active material and a current collector, or for example, mixing a negative electrode active material, a binder, and a conductive material as necessary. Then, a paste-like negative electrode material obtained by adding an appropriate solvent may be applied on the surface of the current collector and dried, and may be compressed and formed as necessary to increase the electrode density. The negative electrode active material preferably has an oxidation-reduction potential in a range of 1.2 V or more and 2.5 V or less, more preferably in a range of 1.5 V or more and 2.5 V or less in terms of Li reference potential. With the negative electrode active material in this range, the voltage of the aqueous secondary battery can be further increased. This negative electrode active material can be a metal oxide containing one or more of Nb, Ru and Ti, and one or more of niobium oxide, ruthenium oxide and lithium titanium composite oxide. Specifically, the negative electrode active material may be one or more of Nb 2 O 5 , NbO 2 , RuO 2 and Li 4 Ti 5 O 12 . As the binder and the solvent used for the negative electrode, those exemplified for the positive electrode can be used. The current collector of the negative electrode includes copper, nickel, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc., as well as adhesiveness, conductivity and reduction resistance improvement. For the purpose, for example, those obtained by treating the surface of copper or the like with carbon, nickel, titanium, silver, or the like can be used. For these, the surface can be oxidized. The shape of the current collector can be the same as that of the positive electrode.

この負極には、Ｚｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を導電材として含む。これらの金属粉体あるいは化合物粉体は、水溶液系二次電池の放電容量をより高めることができる。この導電材は、Ｚｎ、Ａｌ、Ｍｇ、Ｓｉ及びＳｎが好ましく、ＺｎやＭｇがより好ましい。特に、この負極は、Ａｌ集電体を含み、負極活物質としてリチウムチタン複合酸化物を有し、導電材としてＭｇ粉末を含むものがより好ましい。このような構成にすると、放電電位をより向上することができ、エネルギー密度やエネルギー効率などを含む充放電特性をより高めることができる。この負極に含まれる導電材の粒径は、２００μｍ以下であることが好ましく、１００μｍ以下であることがより好ましく、５０μｍ以下であることが更に好ましい。導電材の粒径が小さいほど、導電性を高めることができ、負極合材を形成する厚さの調整も行いやすい。導電材は、負極活物質と導電材と結着材とを含む負極合材の全体のうち３０質量％以上６０質量％以下の範囲で含まれていることが好ましい。導電材の含有量が３０質量％以上では、導電材の機能を発揮しやすい。また、導電材の含有量が６０質量％以下では、相対的に負極活物質を多くできるため、電池容量の低下をより抑制することができる。なお、導電材の含有量の数値が比較的大きいのは、金属粉体は炭素材料などに比して質量が大きいためである。導電材の含有量は、４０質量％以上としてもよいし、４５質量％以上としてもよい。また、導電材の含有量は、５５質量％以下としてもよいし、５０質量％以下としてもよい。なお、負極活物質や導電材などの含有量は、製造時に用いる溶媒などの揮発成分を除いた固形成分で算出するものとする。   The negative electrode contains one or more powders of Zn, Al, Mg, Si, Sn and TaB as a conductive material. These metal powders or compound powders can further increase the discharge capacity of the aqueous secondary battery. This conductive material is preferably Zn, Al, Mg, Si and Sn, and more preferably Zn or Mg. In particular, the negative electrode preferably contains an Al current collector, has a lithium-titanium composite oxide as a negative electrode active material, and contains Mg powder as a conductive material. With such a configuration, the discharge potential can be further improved, and charge / discharge characteristics including energy density and energy efficiency can be further improved. The particle size of the conductive material contained in the negative electrode is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. As the particle size of the conductive material is smaller, the conductivity can be increased, and the thickness for forming the negative electrode mixture can be easily adjusted. The conductive material is preferably contained in the range of 30% by mass or more and 60% by mass or less of the whole negative electrode mixture including the negative electrode active material, the conductive material, and the binder. When the content of the conductive material is 30% by mass or more, the function of the conductive material is easily exerted. In addition, when the content of the conductive material is 60% by mass or less, the amount of the negative electrode active material can be relatively increased, so that a decrease in battery capacity can be further suppressed. The reason why the numerical value of the content of the conductive material is relatively large is that the metal powder has a larger mass than a carbon material or the like. The content of the conductive material may be 40% by mass or more, or may be 45% by mass or more. Further, the content of the conductive material may be 55% by mass or less, or may be 50% by mass or less. Note that the contents of the negative electrode active material, the conductive material, and the like are calculated based on solid components excluding volatile components such as a solvent used in the production.

本開示の水溶液系電解液としては、支持塩を含む水溶液を用いることができる。溶媒は水である。支持塩としては、例えば、リチウムビス（トリフルオロメタンスルホニル）アミド（Ｌｉ（ＣＦ3ＳＯ2）2Ｎ：ＬｉＴＦＳＡ）、リチウムビス（フルオロスルホニル）アミド（Ｌｉ（ＳＯ2Ｆ）2Ｎ：ＬｉＦＳＡ）、Ｌｉ（Ｃ2Ｆ5ＳＯ2）2Ｎ（ＬｉＢＥＴＩ）のうち１以上が挙げられる。このうち、ＬｉＴＦＳＡやＬｉＦＳＡなどが好ましい。この水溶液系電解液は、ＬｉＣＦ3ＳＯ3やＬｉ（Ｃ2Ｆ5ＳＯ2）2Ｎを３０体積％以下の範囲で含むものとしてもよい。この支持塩は、その濃度が希薄系から飽和状態まで溶解したものも可能である。このうち、水溶液系電解液としては、作動電圧を高める観点からは、支持塩を高濃度（例えば、５ｍｏｌ／Ｌ以上や１０ｍｏｌ／Ｌ以上、２０ｍｏｌ／Ｌ以上など）に溶解した水溶液とすることが好ましい。支持塩と水の混合比はモル比で１：２〜１：４であるものとしてもよい。 As the aqueous electrolyte solution of the present disclosure, an aqueous solution containing a supporting salt can be used. The solvent is water. Examples of the supporting salt include lithium bis (trifluoromethanesulfonyl) amide (Li (CF 3 SO 2 ) 2 N: LiTFSA), lithium bis (fluorosulfonyl) amide (Li (SO 2 F) 2 N: LiFSA), and Li One or more of (C 2 F 5 SO 2 ) 2 N (LiBETI) are exemplified. Of these, LiTFSA and LiFSA are preferred. This aqueous electrolyte solution may contain LiCF 3 SO 3 or Li (C 2 F 5 SO 2 ) 2 N in a range of 30% by volume or less. The supporting salt may be dissolved in a concentration ranging from a dilute system to a saturated state. Among these, from the viewpoint of increasing the operating voltage, the aqueous solution is preferably an aqueous solution in which the supporting salt is dissolved in a high concentration (for example, 5 mol / L or more, 10 mol / L or more, 20 mol / L or more). preferable. The mixing ratio of the supporting salt and water may be 1: 2 to 1: 4 in molar ratio.

あるいは、水溶液系電解液は、スルホン酸アルカリ基を２以上有するスルホン酸化合物を支持塩とする水溶液としてもよい。このスルホン酸化合物は、例えば、芳香環構造を有する芳香族系スルホン酸化合物としてもよいし、炭素の鎖状構造を有する脂肪族系スルホン酸化合物としてもよい。芳香族系スルホン酸化合物としては、例えば、ビフェニルなど２以上の芳香環が結合した芳香族多環化合物としてもよいし、ナフタレンやアントラセン、ピレンなど２以上の芳香環が縮合した縮合多環化合物としてもよい。なお、水への溶解性を考慮すると芳香環は少ない方が望ましい。この芳香族系スルホン酸化合物としては、例えば、ベンゼンジスルホン酸リチウム、ベンゼンジスルホン酸ナトリウム、ナフタレンジスルホン酸リチウム、ナフタレンジスルホン酸ナトリウムなどが挙げられる。また、脂肪族系スルホン酸化合物としては、炭素数１〜６の鎖状構造を有するものが挙げられ、末端側にスルホン酸アルカリ基が結合されたものとしてもよい。この脂肪族系スルホン酸化合物としては、例えば、プロパンジスルホン酸リチウム（ＰＤＳＬ）やプロパンジスルホン酸ナトリウム（ＰＤＳＮ）などが挙げられる。これらの有機化合物は、水への溶解度ができるだけ高いことが望ましい。このスルホン酸化合物の支持塩は、その濃度が希薄系から飽和状態まで溶解したものも利用可能である。この支持塩の濃度は、０．５ｍｏｌ／Ｌ以上であることが好ましく、１．０ｍｏｌ／Ｌ以上であることがより好ましく、１．５ｍｏｌ／Ｌ以上であることが更に好ましい。また、支持塩の濃度は、より高いことが好ましく、飽和状態が好ましい。プロパンジスルホン酸リチウムを支持塩の例として説明すると、０．５ｍｏｌ／Ｌ以上３．７９ｍｏｌ／Ｌ以下の範囲が好ましい。この濃度が０．５ｍｏｌ／Ｌ以上では、水溶液系電解液の電位窓が２．０Ｖ以上とすることができ、高い作動電圧を得ることができる。この水溶液系電解液は、電位窓がＬｉ基準電位において、１．７Ｖ以上４．９Ｖ以下の範囲であるものとしてもよい。この電位窓の下限値はより低いことが好ましく、上限値はより高いことが好ましい。この水溶液系電解液を用いる際は、電位窓の下限電位から、負極活物質としてＮｂ2Ｏ5、ＮｂＯ2、ＲｕＯ2及びＬｉ4Ｔｉ5Ｏ12のうち１以上を用いることができる。水溶液系電解液の電位窓は、水溶液系電解液のサイクリックボルタモグラムを測定し、その曲線の平坦領域から求めることができる。 Alternatively, the aqueous electrolyte solution may be an aqueous solution using a sulfonic acid compound having two or more sulfonic acid alkali groups as a supporting salt. The sulfonic acid compound may be, for example, an aromatic sulfonic acid compound having an aromatic ring structure or an aliphatic sulfonic acid compound having a carbon chain structure. The aromatic sulfonic acid compound may be, for example, an aromatic polycyclic compound in which two or more aromatic rings such as biphenyl are bonded, or a condensed polycyclic compound in which two or more aromatic rings such as naphthalene, anthracene, and pyrene are condensed. Is also good. In consideration of solubility in water, it is preferable that the number of aromatic rings is small. Examples of the aromatic sulfonic acid compound include lithium benzenedisulfonate, sodium benzenedisulfonate, lithium naphthalenedisulfonic acid, and sodium naphthalenedisulfonic acid. In addition, examples of the aliphatic sulfonic acid compound include those having a chain structure having 1 to 6 carbon atoms, and those having an alkali sulfonic acid group bonded to the terminal side may be used. Examples of the aliphatic sulfonic acid compound include lithium propane disulfonic acid (PDSL) and sodium propane disulfonic acid (PDSN). It is desirable that these organic compounds have as high a solubility in water as possible. As the supporting salt of the sulfonic acid compound, a solution in which the concentration is dissolved from a dilute system to a saturated state can be used. The concentration of the supporting salt is preferably at least 0.5 mol / L, more preferably at least 1.0 mol / L, even more preferably at least 1.5 mol / L. Further, the concentration of the supporting salt is preferably higher, and a saturated state is preferable. When lithium propane disulfonate is described as an example of the supporting salt, the range is preferably 0.5 mol / L or more and 3.79 mol / L or less. When the concentration is 0.5 mol / L or more, the potential window of the aqueous electrolyte solution can be 2.0 V or more, and a high operating voltage can be obtained. This aqueous electrolyte solution may have a potential window in a range of 1.7 V to 4.9 V at the Li reference potential. The lower limit of this potential window is preferably lower and the upper limit is preferably higher. When this aqueous electrolyte is used, one or more of Nb 2 O 5 , NbO 2 , RuO 2 and Li 4 Ti 5 O 12 can be used as the negative electrode active material from the lower limit potential of the potential window. The potential window of the aqueous electrolyte solution can be determined from the flat region of the curve by measuring the cyclic voltammogram of the aqueous electrolyte solution.

この水溶液系電解液は、キャリアの支持塩とは異なるカチオンを含む添加剤が添加されていることが好ましい。この添加剤としては、例えば、カチオンとしてＭｇ、Ｃａ及びＣｓなどを含むものが挙げられる。この添加剤は、上述した支持塩と同じアニオンを含むものを用いることができる。具体的には、ＭｇＴＦＳＡ、ＣａＴＦＳＡ、ＣｓＴＦＳＡなどが挙げられる。この添加剤は、例えば、１．０ｍｏｌ％以上含まれているものとしてもよいし、５．０ｍｏｌ％以下含まれているものとしてもよい。   It is preferable that an additive containing a cation different from the supporting salt of the carrier is added to the aqueous electrolyte solution. Examples of the additive include those containing Mg, Ca, Cs, and the like as cations. As this additive, one containing the same anion as the above-mentioned supporting salt can be used. Specifically, MgTFSA, CaTFSA, CsTFSA and the like can be mentioned. For example, the additive may be contained at 1.0 mol% or more, or may be contained at 5.0 mol% or less.

本開示の水溶液系二次電池は、負極と正極との間にセパレータを備えていてもよい。セパレータとしては、水溶液系二次電池の使用範囲に耐えうる組成であれば特に限定されないが、例えば、ポリプロピレン製不織布やポリフェニレンスルフィド製不織布などの高分子不織布、ポリエチレンやポリプロピレンなどのオレフィン系樹脂の薄い微多孔膜が挙げられる。あるいは、濾紙をセパレータとして用いてもよい。これらは単独で用いてもよいし、複数を混合して用いてもよい。   The aqueous secondary battery of the present disclosure may include a separator between the negative electrode and the positive electrode. The separator is not particularly limited as long as it has a composition that can withstand the use range of the aqueous secondary battery.For example, a polymer nonwoven fabric such as a polypropylene nonwoven fabric or a polyphenylene sulfide nonwoven fabric, or a thin olefin resin such as polyethylene or polypropylene is used. Microporous membranes. Alternatively, filter paper may be used as the separator. These may be used alone or in combination of two or more.

この水溶液系二次電池の形状は、特に限定されないが、例えばコイン型、ボタン型、シート型、積層型、円筒型、偏平型、角型などが挙げられる。また、電気自動車等に用いる大型のものなどに適用してもよい。図３は、本明細書で開示する水溶液系二次電池２０の一例を示す模式図である。この水溶液系二次電池２０は、カップ形状の電池ケース２１と、正極活物質を有しこの電池ケース２１の下部に設けられた正極２２と、負極活物質を有し正極２２に対してセパレータ２４を介して対向する位置に設けられた負極２３と、絶縁材により形成されたガスケット２５と、電池ケース２１の開口部に配設されガスケット２５を介して電池ケース２１を密封する封口板２６と、水溶液系電解液２７とを備えている。この水溶液系二次電池２０は、Ｚｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を導電材として負極２３に含む。   The shape of the aqueous secondary battery is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a stacked type, a cylindrical type, a flat type, and a square type. Further, the present invention may be applied to a large vehicle used for an electric vehicle or the like. FIG. 3 is a schematic diagram illustrating an example of the aqueous secondary battery 20 disclosed in this specification. The aqueous secondary battery 20 includes a cup-shaped battery case 21, a positive electrode 22 having a positive electrode active material and provided below the battery case 21, and a separator 24 having a negative electrode active material and a positive electrode 22. A gasket 25 formed of an insulating material; a sealing plate 26 disposed at an opening of the battery case 21 and sealing the battery case 21 through the gasket 25; And an aqueous electrolyte 27. This aqueous secondary battery 20 includes the negative electrode 23 as a conductive material containing at least one powder of Zn, Al, Mg, Si, Sn, and TaB.

本開示の水溶液系二次電池は、正極内の正極活物質量に対する負極内の負極活物質量から求められる容量比（負極活物質容量／正極活物質容量）が１．２以上２．４以下の範囲であることが好ましい。この容量比が１．２以上では、より安定的に水溶液系二次電池の出力特性を高めることができる。また、導電材としてＺｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を用いることにより、容量比を２．４以下としても十分な放電容量を示すことができる。この容量比は、１．５以上がより好ましく、２．０以上が更に好ましい。なお、セルの容積などを考慮すると、この容量比は、５以下であるものとしてもよい。水溶液系電解液の電位窓の下限電位は還元分解電位に相当し、この電位を下回ると電解液が負極において電気分解する。負極では、放電開始時から徐々に電位が低下することから、負極の容量をより大きくすると、正極での容量との兼ね合いからこの電位低下をより抑制することができる。このような理由から、容量比はより大きいことが望ましい。なお、この容量比は、水溶液系二次電池の用途に合わせて適宜設定すればよい。   In the aqueous secondary battery of the present disclosure, the capacity ratio (negative electrode active material capacity / positive electrode active material capacity) obtained from the amount of the negative electrode active material in the negative electrode to the amount of the positive electrode active material in the positive electrode is 1.2 or more and 2.4 or less. Is preferably within the range. When the capacity ratio is 1.2 or more, the output characteristics of the aqueous secondary battery can be more stably improved. In addition, by using one or more powders of Zn, Al, Mg, Si, Sn, and TaB as the conductive material, a sufficient discharge capacity can be exhibited even when the capacity ratio is set to 2.4 or less. This capacity ratio is more preferably 1.5 or more, and even more preferably 2.0 or more. In consideration of the cell volume and the like, the capacity ratio may be set to 5 or less. The lower limit potential of the potential window of the aqueous electrolyte solution corresponds to the reductive decomposition potential. When the potential falls below this potential, the electrolytic solution is electrolyzed at the negative electrode. In the negative electrode, since the potential gradually decreases from the start of discharge, if the capacity of the negative electrode is increased, the decrease in the potential can be further suppressed in consideration of the capacity of the positive electrode. For this reason, it is desirable that the capacity ratio be larger. Note that this capacity ratio may be appropriately set according to the use of the aqueous secondary battery.

以上詳述した水溶液系二次電池では、放電容量をより向上するなど、充放電特性をより向上することができる。このような効果が得られる理由は、例えば、以下のように考えられる。この水溶液系二次電池では、例えば、一般的に導電材として用いられる炭素材料ではない、Ｚｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の特定の粉体を導電材として負極に含む。これらの導電材は、負極での水の電気分解をより抑制することができ、その結果、放電容量がより向上するものと推察される。   In the aqueous secondary battery described in detail above, the charge / discharge characteristics can be further improved, for example, the discharge capacity can be further improved. The reason why such an effect is obtained is considered, for example, as follows. In this aqueous secondary battery, for example, the negative electrode contains one or more specific powders of Zn, Al, Mg, Si, Sn and TaB, which are not carbon materials generally used as a conductive material, as a conductive material. . It is presumed that these conductive materials can further suppress the electrolysis of water at the negative electrode, and as a result, the discharge capacity is further improved.

なお、本開示は上述した実施形態に何ら限定されることはなく、本開示の技術的範囲に属する限り種々の態様で実施し得ることはいうまでもない。   Note that the present disclosure is not limited to the above-described embodiments at all, and it goes without saying that the present disclosure can be implemented in various modes as long as it belongs to the technical scope of the present disclosure.

例えば上述した実施形態では、リチウムをアルカリ金属元素の主として説明したが、特にこれに限定されず、ナトリウムやカリウムとしてもよい。例えば、支持塩をＬｉＴＦＳＡやＬｉＦＳＡとして説明したが、ＮａＴＦＳＡやＮａＦＳＡとしてもよい。   For example, in the above-described embodiment, lithium is mainly described as an alkali metal element. However, the present invention is not particularly limited to this, and lithium and sodium may be used. For example, the supporting salt is described as LiTFSA or LiFSA, but may be NaTFSA or NaFSA.

以下には、本明細書で開示する水溶液系二次電池を具体的に作製した例を実験例として説明する。なお、実験例１、６、７、１０、１１、１３、１５、１６、１７〜１９、２２、２４が実施例に該当し、実験例２〜５、８、９、１２、１４、２０、２１、２３、２５が比較例に該当する。   Hereinafter, an example in which the aqueous secondary battery disclosed in this specification is specifically manufactured will be described as an experimental example. Experimental examples 1, 6, 7, 10, 11, 13, 15, 16, 17 to 19, 22, and 24 correspond to the examples, and experimental examples 2 to 5, 8, 9, 12, 14, 20, and 20. 21, 23 and 25 correspond to comparative examples.

［実験例１］
正極は以下のように作製した。スピネル型のアルミニウム置換リチウムマンガン酸化物（三井住友金属鉱山製：Ｌｉ1.1Ａｌ0.1Ｍｎ1.9Ｏ4）と、導電材（東海カーボン製ＴＢ５５００）、結着材としてのＰＶｄＦ（呉羽化学製♯１３２０）をＮ−メチルピロリドン（ＮＭＰ）と共に湿式混合した。混合には、混練機（シンキー製泡とり錬太郎）を用いた。これを２０μｍ厚のアルミニウム箔上に塗工し、１５０℃で真空乾燥した。その後、直径１４ｍｍに打ち抜き、これをプレスして正極とした。正極合材層の厚さは４０μｍであった。活物質：導電材：結着材の最終的な割合は、質量比で７７：１４：９であった。また、正極活物質の目付け量は、６．５５ｍｇ／ｃｍ2であった。負極は以下のように作製した。Ｎｂ2Ｏ5（アルドリッチ製）と導電材としての亜鉛ナノ粉末（アルドリッチ製、１μｍ以下（カタログ値））、結着材としての結着材としてのＰＶｄＦ（呉羽化学製♯９３０５）をＮＭＰと共に湿式混合し負極合材を得た。この負極合材を、アルミニウム箔上に塗工し、１５０℃で真空乾燥した。その後、直径１４ｍｍに打ち抜き、これをプレスして負極とした。負極合材層の厚さは４０μｍであった。活物質：金属粒子：結着材の最終的な割合は、質量比で３９．９：５４．３：５．８であった。また、正極活物質の目付け量は、６．５５ｍｇ／ｃｍ2であった。仕込み量から計算された負極活物質と正極活物質の容量比は２．１１であった。 [Experimental example 1]
The positive electrode was produced as follows. A spinel-type aluminum-substituted lithium manganese oxide (manufactured by Sumitomo Mitsui Metal Mining: Li 1.1 Al 0.1 Mn 1.9 O 4 ), a conductive material (TB5500 manufactured by Tokai Carbon), and PVdF (# 1320 manufactured by Kureha Chemical) as a binder It was wet mixed with N-methylpyrrolidone (NMP). For the mixing, a kneader (Rintaro Awatori, manufactured by Sinky) was used. This was applied on an aluminum foil having a thickness of 20 μm, and vacuum dried at 150 ° C. Then, it was punched to a diameter of 14 mm and pressed to obtain a positive electrode. The thickness of the positive electrode mixture layer was 40 μm. The final ratio of active material: conductive material: binder was 77: 14: 9 by mass. The basis weight of the positive electrode active material was 6.55 mg / cm 2 . The negative electrode was manufactured as follows. Nb 2 O 5 (manufactured by Aldrich), zinc nanopowder (manufactured by Aldrich, 1 μm or less (catalog value)) as a conductive material, PVdF (manufactured by Kureha Chemical # 9305) as a binder as a binder were wet-processed together with NMP. The mixture was mixed to obtain a negative electrode mixture. This negative electrode mixture was applied on an aluminum foil and vacuum dried at 150 ° C. Then, it was punched to a diameter of 14 mm and pressed to obtain a negative electrode. The thickness of the negative electrode mixture layer was 40 μm. The final ratio of active material: metal particles: binder was 39.9: 54.3: 5.8 by mass ratio. The basis weight of the positive electrode active material was 6.55 mg / cm 2 . The capacity ratio between the negative electrode active material and the positive electrode active material calculated from the charged amount was 2.11.

上記正極と負極とをセパレータを挟んで対向させ、電解液を入れて加圧型コインセルを組んだ。電解液として、Ｌｉ（ＣＦ3ＳＯ2）2Ｎ（ＬｉＴＦＳＡ、キシダ化学製）を溶解した水溶液（２２．２ｍｏｌ／Ｌ）に添加剤としてのＭｇ（ＴＦＳＡ）2をモル比で３．５％添加したものを用いた。 また、セパレータとして、濾紙（桐山製５Ｃ）を用いた。得られたものを実験例１のセルとした。このセルを用い、２５℃で０．１ｍＡ／ｃｍ2の電流密度で２．７Ｖまで充電し、その後０．０４ｍＡ／ｃｍ2の電流密度で１．２Ｖまで放電させた。１サイクル目における実験例１のセルの正極活物質あたりの放電容量は、１００ｍＡｈ／ｇであった。なお、実験例１〜１４の正極及び負極の詳細と、負極容量／正極容量の容量比、電解液の詳細、及び１サイクル目の放電用をまとめて表１、２に示した。 The positive electrode and the negative electrode were opposed to each other with a separator interposed therebetween, and an electrolytic solution was charged to form a pressurized coin cell. As an electrolytic solution, 3.5% by mole of Mg (TFSA) 2 as an additive was added to an aqueous solution (22.2 mol / L) in which Li (CF 3 SO 2 ) 2 N (LiTFSA, manufactured by Kishida Chemical) was dissolved. What was done was used. In addition, filter paper (Kiriyama 5C) was used as a separator. The obtained one was used as the cell of Experimental Example 1. Using this cell, charged to 2.7V at a current density of 0.1 mA / cm 2 at 25 ° C., it was then discharged at a current density of 0.04 mA / cm 2 until 1.2V. The discharge capacity per positive electrode active material of the cell of Experimental Example 1 in the first cycle was 100 mAh / g. Tables 1 and 2 collectively show details of the positive electrode and the negative electrode, the capacity ratio of negative electrode capacity / positive electrode capacity, details of the electrolytic solution, and the first cycle discharge for Experimental Examples 1 to 14.

［実験例２〜５］
負極において、Ｎｂ2Ｏ5とカーボンブラック（ＣＢ：東海カーボン製ＴＢ５５００）とＰＶｄＦとを質量比で８０：１２：８とし、負極／正極容量比を１．７９とした以外は、実験例１と同様の工程を経て得られたものを実験例２のセルとした。実験例２のセルの正極活物質あたりの放電容量は、７８ｍＡｈ／ｇであった。また、電解液にＭｇ（ＴＦＳＡ）2を含まないものを用い、負極／正極容量比を３．１８とした以外は実験例２と同様の工程を経て得られたものを実験例３のセルとした。この実験例３の正極活物質あたりの放電容量は、６５ｍＡｈ／ｇであった。また、負極／正極容量比を２．４９とした以外は実験例３と同様の工程を経て得られたものを実験例４のセルとした。この実験例４の正極活物質あたりの放電容量は、５０ｍＡｈ／ｇであった。また、負極／正極容量比を１．６１とした以外は実験例３と同様の工程を経て得られたものを実験例５のセルとした。この実験例５の正極活物質あたりの放電容量は、３２ｍＡｈ／ｇであった。 [Experimental Examples 2 to 5]
Experimental Example 1 was repeated except that the mass ratio of Nb 2 O 5 , carbon black (CB: TB5500 made by Tokai Carbon) and PVdF was 80: 12: 8, and the anode / cathode capacity ratio was 1.79. The cell obtained through the same steps was used as the cell of Experimental Example 2. The discharge capacity per positive electrode active material of the cell of Experimental Example 2 was 78 mAh / g. Further, a cell obtained in the same manner as in Experimental Example 2 except that the electrolytic solution did not contain Mg (TFSA) 2 and the negative electrode / positive electrode capacity ratio was set to 3.18 was referred to as a cell of Experimental Example 3. did. The discharge capacity per positive electrode active material of Experimental Example 3 was 65 mAh / g. A cell obtained in the same manner as in Experimental Example 3 except that the negative electrode / positive electrode capacity ratio was set to 2.49 was used as a cell in Experimental Example 4. The discharge capacity per positive electrode active material of Experimental Example 4 was 50 mAh / g. A cell obtained through the same process as in Experimental Example 3 except that the negative electrode / positive electrode capacity ratio was 1.61 was used as a cell of Experimental Example 5. The discharge capacity per positive electrode active material of Experimental Example 5 was 32 mAh / g.

［実験例６］
負極において、Ｎｂ2Ｏ5と亜鉛ナノ粉末とＰＶｄＦとを質量比で５６：３８：６とし、負極／正極容量比を２．０５とした以外は、実験例１と同様の工程を経て得られたものを実験例６のセルとした。実験例６のセルの正極活物質あたりの放電容量は、１０２ｍＡｈ／ｇであった。 [Experimental example 6]
In the negative electrode, Nb 2 O 5 , zinc nanopowder, and PVdF were obtained through the same steps as in Experimental Example 1 except that the mass ratio was 56: 38: 6 and the negative electrode / positive electrode capacity ratio was 2.05. This was used as the cell of Experimental Example 6. The discharge capacity per positive electrode active material of the cell of Experimental Example 6 was 102 mAh / g.

［実験例７］
正極活物質にスピネル型のリチウムマンガン酸化物（ＬｉＭｎ2Ｏ4：アルドリッチ）を用い、電解液にプロパンジスルホニルリチウム（ＰＤＳＬ）の水溶液（濃度３．７９ｍｏｌ／Ｌ）を用い、正極の活物質と導電材と結着材との質量比を７６：１１：１３とし、負極／正極容量比を２．０８とした以外は実験例６と同様の工程を経て得られたものを実験例７のセルとした。実験例７の正極活物質あたりの放電容量は、１０２ｍＡｈ／ｇであった。 [Experimental example 7]
A spinel-type lithium manganese oxide (LiMn 2 O 4 : Aldrich) was used as a positive electrode active material, and an aqueous solution (concentration 3.79 mol / L) of propane disulfonyl lithium (PDSL) was used as an electrolyte. A cell obtained in the same manner as in Experimental Example 6 except that the mass ratio of the conductive material to the binder was set to 76:11:13 and the negative electrode / positive electrode capacity ratio was set to 2.08 And The discharge capacity per positive electrode active material of Experimental Example 7 was 102 mAh / g.

［実験例８、９］
実験例２の負極を用い、負極／正極容量比を３．３２とした以外は実験例７と同様の工程を経て得られたものを実験例８のセルとした。実験例８の正極活物質あたりの放電容量は、４６ｍＡｈ／ｇであった。負極／正極容量比を４．４３とした以外は実験例８と同様の工程を経て得られたものを実験例９のセルとした。実験例９の正極活物質あたりの放電容量は、６６ｍＡｈ／ｇであった。 [Experimental Examples 8, 9]
A cell obtained in Experimental Example 8 was obtained through the same steps as in Experimental Example 7 except that the negative electrode of Experimental Example 2 was used and the negative electrode / positive electrode capacity ratio was 3.32. The discharge capacity per positive electrode active material in Experimental Example 8 was 46 mAh / g. A cell obtained in the same manner as in Experimental Example 8 except that the negative electrode / positive electrode capacity ratio was set to 4.43 was used as a cell in Experimental Example 9. The discharge capacity per positive electrode active material in Experimental Example 9 was 66 mAh / g.

［実験例１０］
ＰＤＳＬの水溶液（濃度３．７９ｍｏｌ／Ｌ）に４．５ｍｏｌ％のセシウムビス（トリフルオロメタンスルホニル）アミド（ＣｓＴＦＳＡ）を加えたものを電解液に用い、負極／正極容量比を１．８７とした以外は実験例７と同様の工程を経て得られたものを実験例１０のセルとした。実験例１０の正極活物質あたりの放電容量は、９３ｍＡｈ／ｇであった。 [Experimental example 10]
A solution obtained by adding 4.5 mol% of cesium bis (trifluoromethanesulfonyl) amide (CsTFSA) to an aqueous solution of PDSL (concentration of 3.79 mol / L) was used as an electrolytic solution, and the anode / cathode capacity ratio was set to 1.87. The cell obtained through the same steps as in Experimental Example 7 was used as the cell of Experimental Example 10. The discharge capacity per positive electrode active material of Experimental Example 10 was 93 mAh / g.

［実験例１１、１２］
負極活物質としてチタン酸リチウム（Ｌｉ4Ｔｉ5Ｏ12：ＬＴＯ，石原産業製)を用い、負極の活物質と導電材と結着材との質量比を５４：４０：６とし、負極／正極容量比を１．６９とした以外は実験例１と同様の工程を経て得られたものを実験例１１のセルとした。実験例１１の正極活物質あたりの放電容量は、９７ｍＡｈ／ｇであった。導電材としてＣＢを用い、負極の活物質と導電材と結着材との質量比を８０：１５：５とし、負極／正極容量比を３．４３とした以外は実験例１１と同様の工程を経て得られたものを実験例１２のセルとした。実験例１２の正極活物質あたりの放電容量は、２２ｍＡｈ／ｇであった。 [Experimental Examples 11 and 12]
Lithium titanate (Li 4 Ti 5 O 12 : LTO, manufactured by Ishihara Sangyo) was used as the negative electrode active material, and the mass ratio of the active material, the conductive material, and the binder of the negative electrode was set to 54: 40: 6. A cell obtained through the same steps as in Experimental Example 1 except that the capacity ratio was 1.69 was used as the cell of Experimental Example 11. The discharge capacity per positive electrode active material in Experimental Example 11 was 97 mAh / g. Steps similar to those in Experimental Example 11 except that CB was used as the conductive material, the mass ratio of the active material of the negative electrode, the conductive material, and the binder was 80: 15: 5, and the negative electrode / positive electrode capacity ratio was 3.43. The cell obtained through the above was used as the cell of Experimental Example 12. The discharge capacity per positive electrode active material of Experimental Example 12 was 22 mAh / g.

［実験例１３、１４］
下記の正極を用いた以外は実験例１と同様の工程を経て得られたセルを実験例１０とした。正極活物質としてのスピネル型のニッケル置換リチウムマンガン酸化物（ＬｉＮｉ0.5Ｍｎ1.5Ｏ4 ：アルドリッチ社製）と導電材としてのＣＢ（東海カーボン製ＴＢ５５００）と、結着材としてのＰＶｄＦ（クレハ化学製♯１３２０）とをＮ−メチルピロリドン（ＮＭＰ）とともに湿式混合し正極合材を得た。この正極合材ペーストをＡｌ箔上に塗工し、１５０℃で真空乾燥した。その後、直径１４ｍｍに打ち抜き、これをプレスして正極に用いた。正極合材の厚さは４０μｍであった。活物質と導電材と結着材との最終的な割合は質量比で７５：１２：１３であった。また、負極／正極容量比が２．３９であり、正極活物質の目付け量は、６．５５ｍｇ／ｃｍ2であった。実験例１３の正極活物質あたりの放電容量は、７１ｍＡｈ／ｇであった。また、実験例２の負極を用い、負極／正極容量比を３．６５とした以外は実験例１３と同様の工程を経て得られたものを実験例１４のセルとした。実験例１４の正極活物質あたりの放電容量は、５６ｍＡｈ／ｇであった。 [Experimental examples 13 and 14]
A cell obtained through the same steps as in Experimental Example 1 except that the following positive electrode was used was used as Experimental Example 10. Spinel type nickel-substituted lithium manganese oxide (LiNi 0.5 Mn 1.5 O 4 : manufactured by Aldrich) as a positive electrode active material, CB (TB5500 manufactured by Tokai Carbon) as a conductive material, and PVdF (manufactured by Kureha Chemical Co., Ltd.) as a binder # 1320) was wet-mixed with N-methylpyrrolidone (NMP) to obtain a positive electrode mixture. This positive electrode mixture paste was applied on an Al foil and vacuum dried at 150 ° C. Then, it was punched to a diameter of 14 mm and pressed to use as a positive electrode. The thickness of the positive electrode mixture was 40 μm. The final ratio of the active material, the conductive material, and the binder was 75:12:13 by mass. Further, the negative electrode / positive electrode capacity ratio was 2.39, and the basis weight of the positive electrode active material was 6.55 mg / cm 2 . The discharge capacity per positive electrode active material of Experimental Example 13 was 71 mAh / g. A cell obtained in the same manner as in Example 13 except that the negative electrode of Example 2 was used and the negative electrode / positive electrode capacity ratio was set to 3.65 was used as a cell of Example 14. The discharge capacity per positive electrode active material of Experimental Example 14 was 56 mAh / g.

［実験例１５〜１９］
導電材の微粉末としてＭｇ粉末（高純度化学製、１８０μｍ以下）を負極に用い、負極の活物質と導電材と結着材との割合を質量比で５０：４４：６とし、負極／正極容量比を２．０９とした以外は実験例１と同様の工程を経て得られたものを実験例１５のセルとした。また、導電材の微粉末としてＡｌ粉末（高純度化学製、３μｍ以下）を負極に用い、負極の活物質と導電材と結着材との割合を質量比で４８：４７：５とし、負極／正極容量比を１．７９とした以外は実験例１と同様の工程を経て得られたものを実験例１６のセルとした。また、導電材の微粉末としてＳｉ粉末（高純度化学製、４５μｍ以下）を負極に用い、負極の活物質と導電材と結着材との割合を質量比で５１：４４：５とし、負極／正極容量比を２．２９とした以外は実験例１と同様の工程を経て得られたものを実験例１７のセルとした。また、導電材の微粉末としてＳｎ粉末（アルドリッチ製、１０μｍ以下）を負極に用い、負極の活物質と導電材と結着材との割合を質量比で４８：４７：５とし、負極／正極容量比を２．２３とした以外は実験例１と同様の工程を経て得られたものを実験例１８のセルとした。また、導電材の微粉末としてＴａＢ粉末（アルドリッチ製、１０μｍ以下）を負極に用い、負極の活物質と導電材と結着材との割合を質量比で４２：５３：５とし、負極／正極容量比を１．６９とした以外は実験例１と同様の工程を経て得られたものを実験例１９のセルとした。 [Experimental Examples 15 to 19]
As a fine powder of a conductive material, Mg powder (manufactured by Kojundo Chemical Co., Ltd., 180 μm or less) was used for the negative electrode, and the ratio of the active material of the negative electrode, the conductive material, and the binder was 50: 44: 6 by mass ratio, and the negative electrode / the positive electrode was used. A cell obtained in Experimental Example 15 was obtained through the same steps as in Experimental Example 1 except that the capacity ratio was 2.09. Further, Al powder (3 μm or less, manufactured by Kojundo Chemical Co., Ltd.) was used for the negative electrode as the fine powder of the conductive material, and the mass ratio of the active material of the negative electrode, the conductive material, and the binder was 48: 47: 5. The cell obtained through the same steps as in Experimental Example 1 except that the / positive electrode capacity ratio was 1.79 was used as the cell of Experimental Example 16. In addition, Si powder (45 μm or less, manufactured by High Purity Chemical Co., Ltd.) was used for the negative electrode as a fine powder of the conductive material, and the mass ratio of the active material, the conductive material, and the binder of the negative electrode was 51: 44: 5. A cell obtained through the same steps as in Experimental Example 1 except that the / capacity ratio was set to 2.29 was used as the cell of Experimental Example 17. Also, Sn powder (made by Aldrich, 10 μm or less) was used for the negative electrode as a fine powder of the conductive material, and the mass ratio of the active material of the negative electrode, the conductive material, and the binder was 48: 47: 5, and the negative electrode / the positive electrode was used. A cell obtained in the same manner as in Experimental Example 1 except that the capacity ratio was 2.23 was used as a cell in Experimental Example 18. Also, TaB powder (made by Aldrich, 10 μm or less) was used for the negative electrode as a fine powder of the conductive material, the mass ratio of the active material of the negative electrode, the conductive material, and the binder was 42: 53: 5, and the negative electrode / the positive electrode was used. A cell obtained in Experimental Example 19 was obtained through the same steps as in Experimental Example 1 except that the capacity ratio was 1.69.

［実験例２０、２１］
導電材の微粉末としてＣｏ粉末（高純度化学製、平均粒径５μｍ）を負極に用い、負極の活物質と導電材と結着材との割合を質量比で５０：４５：５とした以外は実験例１と同様の工程を経て得られたものを実験例２０のセルとした。また、導電材の微粉末としてＴｅ粉末（高純度化学製、４５μｍ以下）を負極に用い、負極の活物質と導電材と結着材との割合を質量比で４９：４６：５とした以外は実験例１と同様の工程を経て得られたものを実験例２１のセルとした。 [Experimental Examples 20 and 21]
Except that Co powder (manufactured by Kojundo Chemical Co., Ltd., average particle size: 5 μm) was used for the negative electrode as the fine powder of the conductive material, and the mass ratio of the active material of the negative electrode, the conductive material, and the binder was 50: 45: 5. The cell obtained through the same steps as in Experimental Example 1 was used as the cell of Experimental Example 20. In addition, a Te powder (high purity chemical, 45 μm or less) was used for the negative electrode as the fine powder of the conductive material, and the ratio of the active material, the conductive material, and the binder of the negative electrode was 49: 46: 5 by mass ratio. The cell obtained through the same steps as in Experimental Example 1 was used as the cell of Experimental Example 21.

［実験例２２、２３］
負極活物質としてルテニウム酸化物（ＲｕＯ2、アルドリッチ製、５０μｍ以下）、導電材の微粉末としてＺｎ粉末とＡｌ粉末とを用い、負極の活物質とＺｎ粉末とＡｌ粉末と結着材との割合を質量比で５１：３３：１１：５とし、負極／正極容量比を２．２２とした以外は実験例１と同様の工程を経て得られたものを実験例２２のセルとした。また、導電材をＣＢとし、負極の活物質と導電材と結着材との割合を質量比で７６：１６：８とし、負極／正極容量比を３．８９とした以外は実験例２２と同様の工程を経て得られたものを実験例２３のセルとした。 [Experimental Examples 22, 23]
Using ruthenium oxide (RuO 2 , manufactured by Aldrich, 50 μm or less) as the negative electrode active material, Zn powder and Al powder as the fine powder of the conductive material, the ratio of the negative electrode active material, Zn powder, Al powder, and the binder Was obtained through the same steps as in Experimental Example 1 except that the mass ratio was 51: 33: 11: 5 and the negative electrode / positive electrode capacity ratio was 2.22. Experimental Example 22 except that the conductive material was CB, the mass ratio of the active material of the negative electrode, the conductive material, and the binder was 76: 16: 8, and the negative electrode / positive electrode capacity ratio was 3.89. The cell obtained through the same steps was used as the cell of Experimental Example 23.

［実験例２４、２５］
負極活物質としてＬＴＯ、導電材の微粉末としてＭｇ粉末とＡｌ粉末とを用い、負極の活物質とＭｇ粉末とＡｌ粉末と結着材との割合を質量比で５２：２９：１９：５とし、負極／正極容量比を１．３９とした以外は実験例７と同様の工程を経て得られたものを実験例２４のセルとした。導電材をＣＢとし、負極の活物質と導電材と結着材との割合を質量比で８１：１２：７とした以外は実験例２４と同様の工程を経て得られたものを実験例２５のセルとした。 [Experimental Examples 24 and 25]
LTO was used as the negative electrode active material, and Mg powder and Al powder were used as the fine powder of the conductive material. The mass ratio of the active material of the negative electrode, Mg powder, Al powder, and the binder was 52: 29: 19: 5. The cell obtained in the same manner as in Experimental Example 7 except that the negative electrode / positive electrode capacity ratio was set to 1.39 was used as the cell of Experimental Example 24. Experimental Example 25 was obtained through the same steps as in Experimental Example 24 except that the conductive material was CB and the mass ratio of the active material of the negative electrode, the conductive material, and the binder was 81: 12: 7. Cell.

（結果と考察）
図４は、実験例１〜３の充放電曲線である。図５は、実験例６の３サイクルまでの充放電曲線である。図６は、実験例７、８の充放電曲線である。図７は、実験例１１、１２の充放電曲線である。図８は、実験例１５の充放電曲線である。図９は、実験例１７の充放電曲線である。図１０は、実験例１８の充放電曲線である。図１１は、実験例２４、２５の充放電曲線である。表１、２に実験例１〜２５の正極、負極、電解液の構成及び１サイクル目の放電容量をまとめて示した。図４に示すように、実験例１〜３は、ほぼ同程度の充電容量を示した一方、Ｚｎ粉末を用いた実験例１では、大きく放電容量が向上した。これは、おそらくカーボンブラックを負極の導電材として用いると水の電気分解によりＬｉが消費されて放電容量が低下する一方、Ｚｎ粉末ではそのようなＬｉの消費をより低減することができるためであると推察された。また、図５に示すように、実験例６では、サイクル特性が好適であることがわかった。 (Results and discussion)
FIG. 4 is a charge / discharge curve of Experimental Examples 1 to 3. FIG. 5 is a charge / discharge curve of Experimental Example 6 up to three cycles. FIG. 6 is a charge / discharge curve of Experimental Examples 7 and 8. FIG. 7 is a charge / discharge curve of Experimental Examples 11 and 12. FIG. 8 is a charge / discharge curve of Experimental Example 15. FIG. 9 is a charge / discharge curve of Experimental Example 17. FIG. 10 is a charge / discharge curve of Experimental Example 18. FIG. 11 is a charge / discharge curve of Experimental Examples 24 and 25. Tables 1 and 2 collectively show the configurations of the positive electrode, the negative electrode, and the electrolytic solution and the discharge capacity in the first cycle in Experimental Examples 1 to 25. As shown in FIG. 4, Experimental Examples 1 to 3 exhibited substantially the same charge capacity, while Experimental Example 1 using Zn powder significantly improved the discharge capacity. This is probably because when carbon black is used as the conductive material of the negative electrode, Li is consumed by electrolysis of water and the discharge capacity is reduced, while the consumption of Li can be further reduced in the Zn powder. It was inferred. Further, as shown in FIG. 5, in Experimental Example 6, it was found that the cycle characteristics were favorable.

図６に示すように、スピネル型のリチウムマンガン酸化物を負極活物質とし、導電材をＣＢとし、電解液にＰＤＳＬの水溶液を用いた実験例８においても、充電容量と放電容量との差が大きかった。一方、Ｚｎ粉末を負極に用いた実験例７では、充電容量及び放電容量の向上が認められた。また、図７に示すように、ＬＴＯを負極活物質とする場合においても、Ｚｎ粉末を用いることによって、充放電容量をより向上することができることがわかった。   As shown in FIG. 6, in Experimental Example 8 in which spinel-type lithium manganese oxide was used as the negative electrode active material, the conductive material was CB, and the aqueous solution of PDSL was used as the electrolyte, the difference between the charge capacity and the discharge capacity was small. It was big. On the other hand, in Experimental Example 7 in which Zn powder was used for the negative electrode, improvements in charge capacity and discharge capacity were observed. Also, as shown in FIG. 7, it was found that, even when LTO was used as the negative electrode active material, the charge and discharge capacity could be further improved by using Zn powder.

図８〜１０、表２に示すように、Ｍｇ粉末、Ａｌ粉末、Ｓｉ粉末、Ｓｎ粉末、ＴａＢ粉末においても、Ｚｎ粉末と同様に、充放電容量をより向上することができることがわかった。また、図８に示すように、Ｍｇ粉末においては、放電曲線の電位が２Ｖ以上を示し、且つ分極も少ないため、エネルギー密度やエネルギー効率をより高めることができ、特に好ましいことがわかった。一方、Ｃｏ粉末やＴｅ粉末においては、そのような効果は認められなかった。このため、導電性を有する特定の金属及び化合物において、水溶液系二次電池の負極に添加すると、水の電気分解などにより生じうるロスをより抑制することができることがわかった。   As shown in FIGS. 8 to 10 and Table 2, it was found that the charge / discharge capacity of the Mg powder, the Al powder, the Si powder, the Sn powder, and the TaB powder could be further improved as in the case of the Zn powder. In addition, as shown in FIG. 8, it was found that the Mg powder has a potential of a discharge curve of 2 V or more and has little polarization, so that the energy density and the energy efficiency can be further increased, and thus it is found that the Mg powder is particularly preferable. On the other hand, such effects were not observed with Co powder or Te powder. For this reason, it has been found that when a specific metal or compound having conductivity is added to the negative electrode of an aqueous secondary battery, loss that can be caused by electrolysis of water or the like can be further suppressed.

以上より、Ｚｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を導電材として負極に含む水溶液系二次電池では、放電容量をより向上することができることがわかった。また、その導電材は、２００μｍ以下の粒径、より好ましくは、５０μｍ以下の粒径であることが好ましいことがわかった。また、導電材の粉体は、３０質量％以上６０質量％以下の範囲で含まれることが好ましいことがわかった。また、この水溶液系二次電池では、負極／正極容量比が１．２以上２．４以下の範囲においても、高い放電容量を示すことができることがわかった。特に、Ａｌ集電体と、負極活物質としてのＬＴＯと、導電材としてＭｇ粉末とを含む負極が好ましいことがわかった。なお、導電材は、特に電解液の分解抑制に寄与するものと推察され、放電容量の向上は、正極活物質ではなく、負極や電解液の組成に依拠するものと推察された。   From the above, it has been found that the discharge capacity can be further improved in an aqueous secondary battery including one or more powders of Zn, Al, Mg, Si, Sn, and TaB as a conductive material in a negative electrode. Further, it has been found that the conductive material preferably has a particle size of 200 μm or less, more preferably 50 μm or less. It was also found that the conductive material powder was preferably contained in a range of 30% by mass or more and 60% by mass or less. It was also found that this aqueous secondary battery can exhibit a high discharge capacity even when the negative electrode / positive electrode capacity ratio is in the range of 1.2 or more and 2.4 or less. In particular, it was found that a negative electrode containing an Al current collector, LTO as a negative electrode active material, and Mg powder as a conductive material was preferable. In addition, it was presumed that the conductive material particularly contributed to suppression of decomposition of the electrolytic solution, and it was presumed that the improvement of the discharge capacity depends not on the positive electrode active material but on the composition of the negative electrode or the electrolytic solution.

なお、本開示は上述した実施例に何ら限定されることはなく、本開示の技術的範囲に属する限り種々の態様で実施し得ることはいうまでもない。 It is needless to say that the present disclosure is not limited to the above-described embodiments, and can be implemented in various modes as long as they belong to the technical scope of the present disclosure.

本明細書で開示する水溶液系二次電池は、エネルギー産業、例えば電池産業の分野に利用可能である。   The aqueous secondary battery disclosed in this specification can be used in the field of the energy industry, for example, the battery industry.

２０ 水溶液系二次電池、２１ 電池ケース、２２ 正極、２３ 負極、２４ セパレータ、２５ ガスケット、２６ 封口板、２７ 水溶液系電解液。   Reference Signs List 20 aqueous secondary battery, 21 battery case, 22 positive electrode, 23 negative electrode, 24 separator, 25 gasket, 26 sealing plate, 27 aqueous electrolyte.

Claims (8)

正極活物質を有する正極と、
Ｌｉ基準電位で１．２Ｖ以上２．５Ｖ以下の範囲内に酸化還元電位を有しＮｂ、Ｒｕ及びＴｉのうち１以上を含む金属酸化物を負極活物質として有し、導電材としてのＺｎ、Ａｌ、Ｍｇ、Ｓｉ、Ｓｎ及びＴａＢのうち１以上の粉体を含む負極と、
前記正極と前記負極との間でアルカリ金属イオンを伝導する水溶液系電解液と、
を備えた水溶液系二次電池。 A positive electrode having a positive electrode active material,
A metal oxide having a redox potential within a range of 1.2 V or more and 2.5 V or less at a Li reference potential and containing one or more of Nb, Ru, and Ti as a negative electrode active material; Zn as a conductive material; A negative electrode containing at least one powder of Al, Mg, Si, Sn, and TaB;
An aqueous electrolyte solution that conducts alkali metal ions between the positive electrode and the negative electrode,
Aqueous secondary battery comprising: 前記負極は、２００μｍ以下の粒径の前記導電材を含む、請求項１に記載の水溶液系二次電池。   The aqueous secondary battery according to claim 1, wherein the negative electrode includes the conductive material having a particle size of 200 μm or less. 前記負極は、前記導電材が負極合材のうち３０質量％以上６０質量％以下の範囲で含まれている、請求項１又は２に記載の水溶液系二次電池。   3. The aqueous secondary battery according to claim 1, wherein the negative electrode contains the conductive material in a range of 30% by mass to 60% by mass of the negative electrode mixture. 4. 負極容量を正極容量で除算した負極／正極容量比が１．２以上２．４以下の範囲である、請求項１〜３のいずれか１項に記載の水溶液系二次電池。   The aqueous secondary battery according to any one of claims 1 to 3, wherein a negative electrode / positive electrode capacity ratio obtained by dividing the negative electrode capacity by the positive electrode capacity is in a range of 1.2 or more and 2.4 or less. 前記負極は、Ｎｂ2Ｏ5、ＮｂＯ2、ＲｕＯ2及びＬｉ4Ｔｉ5Ｏ12のうち１以上を前記負極活物質として有している、請求項１〜４のいずれか１項に記載の水溶液系二次電池。 The negative electrode, Nb 2 O 5, NbO 2 , wherein one or more of RuO 2 and Li 4 Ti 5 O 12 has a negative electrode active material, an aqueous solution according to any one of claims 1 to 4 Secondary battery. 前記水溶液系電解液は、リチウムビス（トリフルオロメタンスルホニル）アミド（ＬｉＴＦＳＡ）、リチウムビス（フルオロスルホニル）アミド（ＬｉＦＳＡ）、スルホン酸アルカリ基を２以上有するスルホン酸化合物のうち１以上を含んでいる、請求項１〜５のいずれか１項に記載の水溶液系二次電池。   The aqueous electrolyte solution contains at least one of lithium bis (trifluoromethanesulfonyl) amide (LiTFSA), lithium bis (fluorosulfonyl) amide (LiFSA), and a sulfonic acid compound having two or more alkali sulfonic groups. The aqueous secondary battery according to claim 1. 前記正極は、リチウムマンガン複合酸化物、リチウムニッケルマンガン複合酸化物、リチウムニッケルコバルトマンガン複合酸化物のうち１以上の前記正極活物質を有している、請求項１〜６のいずれか１項に記載の水溶液系二次電池。   The positive electrode according to any one of claims 1 to 6, wherein the positive electrode has one or more positive electrode active materials among lithium manganese composite oxide, lithium nickel manganese composite oxide, and lithium nickel cobalt manganese composite oxide. The aqueous secondary battery according to the above. 前記負極は、前記負極活物質としてリチウムチタン複合酸化物を有し、前記導電材としてＭｇ粉末を含む、請求項１〜７のいずれか１項に記載の水溶液系二次電池。   The aqueous secondary battery according to any one of claims 1 to 7, wherein the negative electrode has a lithium-titanium composite oxide as the negative electrode active material, and includes Mg powder as the conductive material.
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Publication number Priority date Publication date Assignee Title
WO2016114141A1 (en) * 2015-01-14 2016-07-21 国立大学法人 東京大学 Aqueous electrolyte solution for electrical storage device, and electrical storage device including said aqueous electrolyte solution
JP2017027944A (en) * 2015-07-24 2017-02-02 御国色素株式会社 Lithium ion battery
WO2017135323A1 (en) * 2016-02-01 2017-08-10 株式会社 東芝 Secondary battery, assembled battery, battery pack, and vehicle
JP2017174810A (en) * 2016-03-16 2017-09-28 株式会社東芝 Secondary battery, battery pack, and vehicle

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016114141A1 (en) * 2015-01-14 2016-07-21 国立大学法人 東京大学 Aqueous electrolyte solution for electrical storage device, and electrical storage device including said aqueous electrolyte solution
JP2017027944A (en) * 2015-07-24 2017-02-02 御国色素株式会社 Lithium ion battery
WO2017135323A1 (en) * 2016-02-01 2017-08-10 株式会社 東芝 Secondary battery, assembled battery, battery pack, and vehicle
JP2017174810A (en) * 2016-03-16 2017-09-28 株式会社東芝 Secondary battery, battery pack, and vehicle

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