JP6691906B2 - Secondary battery - Google Patents

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JP6691906B2
JP6691906B2 JP2017250737A JP2017250737A JP6691906B2 JP 6691906 B2 JP6691906 B2 JP 6691906B2 JP 2017250737 A JP2017250737 A JP 2017250737A JP 2017250737 A JP2017250737 A JP 2017250737A JP 6691906 B2 JP6691906 B2 JP 6691906B2
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active material
porous
electrode
current collector
secondary battery
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JP2019117716A (en
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奥田　匠昭
匠昭 奥田
佐々木　厳
厳 佐々木
邦光 山本
邦光 山本
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Toyota Motor Corp
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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • 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
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    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
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Description

本発明は、二次電池に関する。   The present invention relates to a secondary battery.

従来、二次電池としては、正極活物質を含む合材を正極集電体に形成し、負極活物質を含む合材を負極集電体に形成し、電解液を含むセパレータを介してこれらを捲回又は積層したものが知られている（例えば、特許文献１参照）。また、電池ケースの内部をセパレーターで正極室と負極室とに分離し、正極室に正極活物質を含むスラリーを供給し、負極室に負極活物質を含むスラリーを供給するものが提案されている（例えば、特許文献２参照）。   Conventionally, as a secondary battery, a composite material containing a positive electrode active material is formed on a positive electrode current collector, a composite material containing a negative electrode active material is formed on a negative electrode current collector, and these are inserted through a separator containing an electrolytic solution. A wound or laminated product is known (see, for example, Patent Document 1). Further, it is proposed that the inside of the battery case is separated into a positive electrode chamber and a negative electrode chamber by a separator, a slurry containing a positive electrode active material is supplied to the positive electrode chamber, and a slurry containing a negative electrode active material is supplied to the negative electrode chamber. (For example, refer to Patent Document 2).

特開２０１４−２２９５４４号公報JP, 2014-229544, A 特開２００９−２２４１４１号公報JP, 2009-224141, A

ところで、近年、二次電池の高容量化が望まれている。特許文献１のような捲回型や積層型の電池において、電池容量を高める方法としては、活物質層の厚膜化や高密度化によって電池内における活物質の充填率を高める方法などがある。しかしながら、活物質層を厚膜化するとイオンの移動距離が長くなり、活物質層を高密度化するとイオンの移動経路が狭くなるため、出力が低下することがあった。また、特許文献２のようなスラリー利用型の電池でも同様に、電池内における活物質の充填率を高めようとすると、イオンの移動距離が長くなったりイオンの移動経路が狭くなったりして、出力が低下することがあった。このため、電池容量を高め、出力低下を抑制することが望まれていた。   By the way, in recent years, there is a demand for higher capacity secondary batteries. As a method of increasing the battery capacity in the wound type or laminated type battery as disclosed in Patent Document 1, there is a method of increasing the filling rate of the active material in the battery by thickening the active material layer or increasing the density. .. However, increasing the thickness of the active material layer increases the migration distance of ions, and increasing the density of the active material layer narrows the migration path of ions, which may reduce the output. In addition, similarly in a battery using a slurry as in Patent Document 2, when an attempt is made to increase the filling rate of the active material in the battery, the migration distance of ions becomes long or the migration path of ions becomes narrow, The output was sometimes reduced. Therefore, it has been desired to increase the battery capacity and suppress the output reduction.

本発明は、このような課題に鑑みなされたものであり、電池容量を高め、出力低下を抑制できる二次電池を提供することを主目的とする。   The present invention has been made in view of such problems, and a main object of the present invention is to provide a secondary battery capable of increasing battery capacity and suppressing output reduction.

上述した目的を達成するために、本発明者らは、鋭意研究した。そして、正極及び負極のうちの一方の活物質を多孔質集電体の孔表面に形成して多孔質電極とし、他方の活物質を含む液状電極を多孔質電極の空隙に充填して二次電池を作製したところ、電池容量を高め、出力低下を抑制できることを見いだし、本発明を完成するに至った。   In order to achieve the above-mentioned object, the present inventors have conducted extensive research. Then, one active material of the positive electrode and the negative electrode is formed on the pore surface of the porous current collector to form a porous electrode, and the liquid electrode containing the other active material is filled in the voids of the porous electrode to form a secondary electrode. When a battery was manufactured, it was found that the battery capacity could be increased and output reduction could be suppressed, and the present invention was completed.

即ち、本発明の二次電池は、
多孔質集電体と、正極活物質及び負極活物質のうちの一方の活物質を含み前記多孔質集電体の孔表面に形成された活物質層と、を有する多孔質電極と、
前記多孔質電極の孔表面に該孔の空隙が残るように形成されたイオン伝導性の絶縁膜と、
前記正極活物質及び前記負極活物質のうちの他方の活物質と支持塩とを含み、前記絶縁膜が形成された前記多孔質電極の前記空隙に充填された液状電極と、
を備えた、ものである。 That is, the secondary battery of the present invention,
Porous current collector, a porous electrode having an active material layer formed on the surface of the pores of the porous current collector containing one active material of the positive electrode active material and the negative electrode active material,
An ion conductive insulating film formed so that voids of the pores remain on the surface of the pores of the porous electrode,
A liquid electrode containing the other active material of the positive electrode active material and the negative electrode active material and a supporting salt, and filled in the voids of the porous electrode in which the insulating film is formed,
It is equipped with.

この二次電池では、電池容量を高め、出力低下を抑制できる。こうした効果が得られる理由は、以下のように推察される。例えば、この二次電池では、多孔質集電体を用いており、集電体の比表面積が大きいため、活物質を形成するのに必要な所定の表面積を確保する際、集電体自体の体積を小さくできる。また、多孔質集電体では、集電体の全体が三次元的に導通しているため、複数の集電体を接続する構成などが必要なく、集電構造を簡略化・小体積化できる。こうして、集電体を含む集電構造の簡略化・小体積化が可能となり、その分だけ活物質の充填率を高めることができる。また、多孔質電極の空隙に液状電極が充填されるため、多孔質電極の空隙を利用して活物質の充填率を高めることができる。このように、活物質の充填率を高めることができるため、電池容量をより高めることができる。また、多孔質電極と液状電極とが絶縁膜を介して至近距離に配置されており、電荷のキャリアであるイオンの移動距離が短いため、イオン伝導抵抗を低減でき、出力低下を抑制できる。   With this secondary battery, it is possible to increase the battery capacity and suppress a decrease in output. The reason why such an effect is obtained is speculated as follows. For example, in this secondary battery, a porous current collector is used, and since the current collector has a large specific surface area, when securing a predetermined surface area necessary for forming the active material, Volume can be reduced. Further, in the porous current collector, since the entire current collector is three-dimensionally conductive, there is no need to connect a plurality of current collectors, and the current collection structure can be simplified and the volume can be reduced. .. In this way, the current collecting structure including the current collector can be simplified and reduced in volume, and the filling rate of the active material can be increased correspondingly. Further, since the liquid electrode is filled in the voids of the porous electrode, the filling rate of the active material can be increased by utilizing the voids of the porous electrode. In this way, the filling rate of the active material can be increased, so that the battery capacity can be further increased. Further, since the porous electrode and the liquid electrode are arranged at a close distance via the insulating film, and the migration distance of the ions, which are charge carriers, is short, the ion conduction resistance can be reduced and the output reduction can be suppressed.

二次電池１０の構成の一例を示す模式図。FIG. 3 is a schematic diagram showing an example of the configuration of the secondary battery 10. 実施例で用いた二次電池６０の構成の概略を示す説明図。Explanatory drawing which shows the outline of a structure of the secondary battery 60 used in the Example.

以下では、本発明の二次電池の好適な実施形態について、図面を用いて説明する。図１は、本発明の一実施形態である二次電池１０の構成の一例を示す模式図である。   Hereinafter, preferred embodiments of the secondary battery of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the configuration of a secondary battery 10 that is an embodiment of the present invention.

二次電池１０は、図１に示すように、多孔質電極２０と、多孔質電極２０の孔表面にこの孔の空隙が残るように形成された絶縁膜３０と、絶縁膜３０が形成された多孔質電極２０の先ほどの空隙に充填された液状電極４０と、を備えている。ここでは、二次電池１０は、リチウムイオンを電荷のキャリアとする、リチウムイオン二次電池であるものとする。また、多孔質電極２０を正極とし、液状電極４０を負極とする。   As shown in FIG. 1, the secondary battery 10 includes a porous electrode 20, an insulating film 30 formed on the surface of the hole of the porous electrode 20 so that voids of the hole remain, and an insulating film 30. The liquid electrode 40 filled in the former void of the porous electrode 20 is provided. Here, the secondary battery 10 is assumed to be a lithium-ion secondary battery that uses lithium ions as charge carriers. Further, the porous electrode 20 serves as a positive electrode and the liquid electrode 40 serves as a negative electrode.

多孔質電極２０は、多孔質集電体２２と、正極活物質２４を含む活物質層２６と、を有している。多孔質集電体２２は、空隙が三次元的に連結した多孔体である。この空隙の直径は、１０μｍ以上が好ましく５０μｍ以上がより好ましく、また、２０００μｍ以下が好ましく１０００μｍ以下がより好ましく６００μｍ以下がさらに好ましい。空隙の直径を１０μｍ以上とすれば、空隙内に負極活物質４４が進入しやすく、２０００μｍ以下とすれば、多孔質電極２０と液状電極４０との間でのイオンの移動距離を短くできる。なお、空隙の直径は、その空隙の外接球の直径とする。多孔質集電体２２の気孔率は、８０％以上９８％以下が好ましい。また、多孔質集電体２２の比表面積は、５００ｍ2／ｍ3以上８０００ｍ2／ｍ3以下が好ましい。多孔質集電体２２の骨格構造は、例えば、三次元の網目状になっている網目構造、三次元の周期極小曲面であるジャイロイド構造、同粒径の粒子を三次元に周期配列したオパール構造の粒子間部分の構造である逆オパール構造、繊維が三次元に絡み合ったファイバー構造、とすることができる。このうち、網目構造や、ジャイロイド構造、逆オパール構造のように規則性の高い構造では、電池反応の均一性を高めることができ、好ましい。多孔質集電体２２の材質は、電子伝導性を有するものであればよく、例えば、ニッケル、アルミニウム、ステンレス鋼、銅、チタン、鉄、白金などの金属や、炭素、導電性高分子、導電性ガラスとすることができる。このうち、ニッケルは正極における耐食性が良好であるとともに強度が高いため好ましく、アルミニウムはニッケルに比べて強度が劣るものの正極における耐食性がより良好であるため好ましい。多孔質集電体２２は、接着性や導電性、耐食性などを向上するために、表面をカーボン、ニッケル、チタン、銀、白金、金などで処理したものとしてもよい。 The porous electrode 20 has a porous current collector 22 and an active material layer 26 containing a positive electrode active material 24. The porous current collector 22 is a porous body in which voids are three-dimensionally connected. The diameter of the voids is preferably 10 μm or more, more preferably 50 μm or more, preferably 2000 μm or less, more preferably 1000 μm or less, and further preferably 600 μm or less. If the diameter of the void is 10 μm or more, the negative electrode active material 44 easily enters the void, and if it is 2000 μm or less, the migration distance of ions between the porous electrode 20 and the liquid electrode 40 can be shortened. The diameter of the void is the diameter of the circumscribing sphere of the void. The porosity of the porous current collector 22 is preferably 80% or more and 98% or less. The specific surface area of the porous current collector 22 is preferably 500 m 2 / m 3 or more and 8000 m 2 / m 3 or less. The skeleton structure of the porous current collector 22 is, for example, a three-dimensional mesh-like network structure, a three-dimensional periodic minimal curved surface gyroid structure, or opal in which particles of the same particle size are three-dimensionally arrayed. An inverse opal structure, which is the structure of the interparticle portion of the structure, or a fiber structure in which fibers are entangled three-dimensionally can be used. Among these, a highly regular structure such as a mesh structure, a gyroid structure, or an inverse opal structure is preferable because the uniformity of the battery reaction can be enhanced. The material of the porous current collector 22 may be any material having electronic conductivity, and examples thereof include metals such as nickel, aluminum, stainless steel, copper, titanium, iron and platinum, carbon, conductive polymers, and conductive materials. It can be made of natural glass. Of these, nickel is preferable because it has good corrosion resistance and high strength in the positive electrode, and aluminum is preferable because it has lower strength than nickel but has better corrosion resistance in the positive electrode. The porous current collector 22 may have the surface thereof treated with carbon, nickel, titanium, silver, platinum, gold or the like in order to improve adhesiveness, conductivity, corrosion resistance and the like.

正極活物質２４としては、例えば、リチウムと遷移金属とを有する化合物、例えば、リチウムと遷移金属元素とを含む酸化物や、リチウムと遷移金属元素とを含むリン酸化合物などが挙げられる。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)ＣｏＯ2などとするリチウムコバルト複合酸化物、基本組成式をＬｉ(1-x)ＮｉＯ2などとするリチウムニッケル複合酸化物、基本組成式をＬｉ(1-x)ＣｏaＮｉbＭｎcＯ2（ａ＞０、ｂ＞０、ｃ＞０、ａ＋ｂ＋ｃ＝１）などとするリチウムコバルトニッケルマンガン複合酸化物、基本組成式をＬｉＶ2Ｏ3などとするリチウムバナジウム複合酸化物、基本組成式をＶ2Ｏ5などとする遷移金属酸化物などを用いることができる。また、基本組成式をＬｉＦｅＰＯ4とするリン酸鉄リチウム化合物などを正極活物質として用いることができる。これらのうち、リチウムコバルトニッケルマンガン複合酸化物、例えば、ＬｉＣｏ1/3Ｎｉ1/3Ｍｎ1/3Ｏ2やＬｉＮｉ0.4Ｃｏ0.3Ｍｎ0.3Ｏ2などが好ましい。なお、「基本組成式」とは、他の元素、例えば、ＡｌやＭｇなどの成分を含んでもよい趣旨である。正極活物質２４の平均粒径は、例えば、１μｍ以上２０μｍ以下とすることができる。ここで、活物質などの粉体の平均粒径は、粉体を電子顕微鏡（ＳＥＭ）観察し、この観察画像に含まれる粉体粒子の直径を測定して平均した値とする。 Examples of the positive electrode active material 24 include a compound containing lithium and a transition metal, such as an oxide containing lithium and a transition metal element, and a phosphoric acid compound containing lithium and a transition metal element. 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., a basic composition Li (1-x) CoO 2 and other lithium cobalt composite oxides, basic composition formula Li (1-x) NiO 2 and other lithium nickel composite oxides, basic composition formula Li (1-x) Co a Ni b Mn c O 2 (a> 0, b> 0, c> 0, a + b + c = 1), etc., lithium cobalt nickel manganese composite oxide, lithium vanadium composite having a basic composition formula such as LiV 2 O 3 An oxide, a transition metal oxide having a basic composition formula of V 2 O 5, or the like can be used. Further, a lithium iron phosphate compound having a basic composition formula of LiFePO 4 can be used as the positive electrode active material. Of these, lithium cobalt nickel manganese composite oxides such as LiCo 1/3 Ni 1/3 Mn 1/3 O 2 and LiNi 0.4 Co 0.3 Mn 0.3 O 2 are preferable. The “basic composition formula” means that other elements, for example, components such as Al and Mg may be included. The average particle size of the positive electrode active material 24 can be, for example, 1 μm or more and 20 μm or less. Here, the average particle size of the powder of the active material or the like is a value obtained by observing the powder with an electron microscope (SEM) and measuring the diameters of the powder particles included in the observed image and averaging the diameters.

活物質層２６は、多孔質集電体２２の孔表面にこの孔を塞がないように形成されている。活物質層２６の厚みは、５μｍ以上が好ましく２５μｍ以上がより好ましく、また、１０００μｍ以下が好ましく２５０μｍ以下がより好ましい。活物質層２６の厚みを５μｍ以上とすれば、活物質層２６をムラ無く形成できるし、１０００μｍ以下とすれば、多孔質集電体２２と正極活物質２４との間の電子伝導をより円滑にできる。活物質層２６は、正極活物質２４のほか、導電材や結着材などを含んでいてもよい。導電材は、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、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、正極活物質２４や導電材を繋ぎ止めて所定の形状を保つ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。   The active material layer 26 is formed on the surface of the holes of the porous current collector 22 so as not to close the holes. The thickness of the active material layer 26 is preferably 5 μm or more, more preferably 25 μm or more, and preferably 1000 μm or less and more preferably 250 μm or less. If the thickness of the active material layer 26 is 5 μm or more, the active material layer 26 can be formed uniformly, and if it is 1000 μm or less, the electron conduction between the porous current collector 22 and the positive electrode active material 24 is smoother. You can The active material layer 26 may include a conductive material, a binder, and the like, in addition to the positive electrode active material 24. The conductive material is not particularly limited as long as it is an electron conductive material that does not adversely affect the battery performance, and examples thereof include graphite such as natural graphite (scaly graphite and flake graphite) and artificial graphite, acetylene black, carbon black, and Ketjen. It is possible to use one or a mixture of two or more of black, carbon whisker, needle coke, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.). Among these, carbon black and acetylene black are preferable as the conductive material. The binding material plays a role of holding the positive electrode active material 24 and the conductive material together and maintaining a predetermined shape, and includes, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluororubber. Fluorine resins, thermoplastic resins such as polypropylene and 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 kinds. Further, it is also possible to use an aqueous dispersion of cellulose-based or styrene-butadiene rubber (SBR), which is an aqueous binder.

絶縁膜３０は、多孔質電極２０の孔表面にこの孔の空隙が残るように形成されたイオン伝導性及び絶縁性を有する膜である。この絶縁膜３０は、多孔質電極２０と液状電極４０との間に介在し、多孔質電極２０と液状電極４０との短絡を防止する。絶縁膜３０としては、イオン伝導性と絶縁性とを有するポリマーが好適である。この絶縁膜３０は、例えば、フッ化ビニリデン（ＶｄＦ）とヘキサフルオロプロピレン（ＨＦＰ）との共重合体や、ポリメタクリル酸メチル（ＰＭＭＡ）、及びＰＭＭＡとアクリルポリマーとの共重合体などが挙げられる。例えば、ＶｄＦとＨＦＰとの共重合体では、後述する電解液４６の一部がこの膜を膨潤ゲル化し、イオン伝導膜となる。この絶縁膜３０の厚さは、例えば、０．５μｍ以上であることが好ましく、２μｍ以上であることがより好ましく、５μｍ以上であるものとしてもよい。厚さが０．５μｍ以上では、絶縁性を確保する上で好ましい。また、絶縁膜３０の厚さは、２０μｍ以下であることが好ましく、１０μｍ以下であることがより好ましい。厚さが２０μｍ以下では、イオン伝導性の低下を抑制できる点で好ましい。このような範囲では、イオン伝導性及び絶縁性が好適である。   The insulating film 30 is a film having ion conductivity and insulating property formed on the surface of the holes of the porous electrode 20 so that voids of the holes remain. The insulating film 30 is interposed between the porous electrode 20 and the liquid electrode 40 to prevent a short circuit between the porous electrode 20 and the liquid electrode 40. As the insulating film 30, a polymer having ionic conductivity and insulating properties is suitable. Examples of the insulating film 30 include a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), polymethyl methacrylate (PMMA), and a copolymer of PMMA and an acrylic polymer. .. For example, in the case of a copolymer of VdF and HFP, a part of the electrolytic solution 46, which will be described later, swells and gels this film and becomes an ion conductive film. The thickness of the insulating film 30 is, for example, preferably 0.5 μm or more, more preferably 2 μm or more, and may be 5 μm or more. When the thickness is 0.5 μm or more, it is preferable in order to secure insulation. Moreover, the thickness of the insulating film 30 is preferably 20 μm or less, and more preferably 10 μm or less. When the thickness is 20 μm or less, it is preferable because a decrease in ionic conductivity can be suppressed. In such a range, ionic conductivity and insulating property are suitable.

液状電極４０は、負極活物質４４と支持塩とを含み、絶縁膜３０が形成された多孔質電極２０の空隙に充填されている。ここでは、液状電極４０は、粉末状の負極活物質４４を電解液４６に分散させたスラリー又は懸濁液である。こうしたものでは、液状電極４０により多くの負極活物質４４を含ませることができる。なお、支持塩は溶媒に溶解されて電解液４６の中に存在している。   The liquid electrode 40 contains a negative electrode active material 44 and a supporting salt, and is filled in the voids of the porous electrode 20 on which the insulating film 30 is formed. Here, the liquid electrode 40 is a slurry or suspension in which a powdery negative electrode active material 44 is dispersed in an electrolytic solution 46. In such a case, the liquid electrode 40 can contain more negative electrode active material 44. The supporting salt is dissolved in the solvent and exists in the electrolytic solution 46.

負極活物質４４としては、例えば、電荷のキャリアであるリチウムを吸蔵放出可能な材料が挙げられる。負極活物質４４は、例えば、リチウム、リチウム合金、スズ化合物などの無機化合物、リチウムイオンを吸蔵・放出可能な炭素質材料、複数の元素を含む複合酸化物、導電性ポリマーなどが挙げられる。炭素質材料は、例えば、コークス類、ガラス状炭素類、グラファイト類、難黒鉛化性炭素類、熱分解炭素類、炭素繊維などが挙げられる。このうち、人造黒鉛、天然黒鉛などのグラファイト類が好ましい。複合酸化物としては、例えば、リチウムチタン複合酸化物やリチウムバナジウム複合酸化物などが挙げられる。負極活物質４４は、粒子状の固体活物質であることが好ましい。負極活物質４４の平均粒径は、例えば、１μｍ以上が好ましく３μｍ以上がより好ましく、また、２０μｍ以下が好ましく１０μｍ以下がより好ましい。１μｍ以上とすれば、液状電極４０の流動性がよく、２０ｍ以下とすれば、負極活物質４４が多孔質電極２０の空隙に侵入しやすい。負極活物質４４の添加量は、液状電極４０の全体の体積に対して３０体積％以上が好ましく６０体積％以上がより好ましく、７５体積％以下が好ましく７０体積％以下がより好ましい。このような範囲では、電池容量を好適なものとすることができる。   As the negative electrode active material 44, for example, a material capable of inserting and extracting lithium, which is a carrier of electric charge, can be used. Examples of the negative electrode active material 44 include inorganic compounds such as lithium, lithium alloys and tin compounds, carbonaceous materials capable of inserting and extracting lithium ions, composite oxides containing a plurality of elements, conductive polymers and the like. Examples of the carbonaceous material include cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, and carbon fibers. Of these, graphites such as artificial graphite and natural graphite are preferable. Examples of the composite oxide include lithium titanium composite oxide and lithium vanadium composite oxide. The negative electrode active material 44 is preferably a particulate solid active material. The average particle diameter of the negative electrode active material 44 is, for example, preferably 1 μm or more, more preferably 3 μm or more, and preferably 20 μm or less, more preferably 10 μm or less. When the thickness is 1 μm or more, the fluidity of the liquid electrode 40 is good, and when the thickness is 20 m or less, the negative electrode active material 44 easily enters the voids of the porous electrode 20. The added amount of the negative electrode active material 44 is preferably 30% by volume or more, more preferably 60% by volume or more, more preferably 75% by volume or less, and more preferably 70% by volume or less with respect to the entire volume of the liquid electrode 40. In such a range, the battery capacity can be made suitable.

電解液４６に含まれる支持塩は、二次電池１０の電荷のキャリアであるリチウムイオンを含むものとしてもよい。こうした支持塩としては、例えば、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＡｓＦ6、ＬｉＣ Ｆ3ＳＯ3、ＬｉＮ（ＣＦ3ＳＯ2）2、ＬｉＣ（ＣＦ3ＳＯ2）3、ＬｉＳｂＦ6、ＬｉＳｉＦ6、ＬｉＡｌＦ4、ＬｉＳＣＮ、ＬｉＣｌＯ4、ＬｉＣｌ、ＬｉＦ、ＬｉＢｒ、ＬｉＩ、ＬｉＡｌＣｌ4などが挙げられる。このうち、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＡｓＦ6、ＬｉＣｌＯ4などの無機塩、及びＬｉＣＦ3ＳＯ3、ＬｉＮ（ＣＦ3ＳＯ2）2、ＬｉＣ（ＣＦ3ＳＯ2）3などの有機塩からなる群より選ばれる１種又は２種以上の塩を組み合わせて用いること が電気特性の点から見て好ましい。この支持塩は、電解液４６における濃度が０．１ｍｏｌ／Ｌ以上５ｍｏｌ／Ｌ以下であることが好ましく、０．５ｍｏｌ／Ｌ以上２ｍｏｌ／Ｌ以下であることがより好ましい。支持塩の濃度が０．１ｍｏｌ／Ｌ以上では、十分な電流密度を得ることができ、５ｍｏｌ／Ｌ以下では、電解液をより安定させることができる。 The supporting salt contained in the electrolytic solution 46 may contain lithium ions which are carriers of electric charge of the secondary battery 10. Examples of such a supporting salt include LiPF 6 , LiBF 4 , LiAsF 6 , LiC F 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiSbF 6 , LiSiF 6 , LiAlF 4 , Examples thereof include LiSCN, LiClO 4 , LiCl, LiF, LiBr, LiI, LiAlCl 4 . Of these, inorganic salts such as LiPF 6 , LiBF 4 , LiAsF 6 and LiClO 4 and organic salts such as LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 and LiC (CF 3 SO 2 ) 3 From the viewpoint of electric characteristics, it is preferable to use one kind or two or more kinds of selected salts in combination. The concentration of the supporting salt in the electrolytic solution 46 is preferably 0.1 mol / L or more and 5 mol / L or less, and more preferably 0.5 mol / L or more and 2 mol / L or less. When the concentration of the supporting salt is 0.1 mol / L or more, a sufficient current density can be obtained, and when it is 5 mol / L or less, the electrolytic solution can be more stabilized.

電解液４６に含まれる溶媒としては、例えば、非水電解液に用いられる溶媒などが挙げられる。こうした溶媒としては、例えば、カーボネート類、エステル類、エーテル類、ニトリル類、フラン類、スルホラン類及びジオキソラン類などが挙げられ、これらを単独又は混合して用いることができる。具体的には、カーボネート類としてエチレンカーボネートやプロピレンカーボネート、ビニレンカーボネート、ブチレンカーボネート、クロロエチレンカーボネートなどの環状カーボネート類や、ジメチルカーボネート、エチルメチルカーボネート、ジエチルカーボネート、エチル−ｎ−ブチルカーボネート、メチル−ｔ−ブチルカーボネート、ジ−ｉ−プロピルカーボネート、ｔ−ブチル−ｉ−プロピルカーボネートなどの鎖状カーボネート類、γ−ブチルラクトン、γ−バレロラクトンなどの環状エステル類、ギ酸メチル、酢酸メチル、酢酸エチル、酪酸メチルなどの鎖状エステル類、ジメトキシエタン、エトキシメトキシエタン、ジエトキシエタンなどのエーテル類、アセトニトリル、ベンゾニトリルなどのニトリル類、テトラヒドロフラン、メチルテトラヒドロフラン、などのフラン類、スルホラン、テトラメチルスルホランなどのスルホラン類、１，３−ジオキソラン、メチルジオキソランなどのジオキソラン類などが挙げられる。このうち、環状カーボネート類と鎖状カーボネート類の組み合わせが好ましい。この組み合わせによると、充放電の繰り返しでの電池特性を表すサイクル特性が優れているばかりでなく、電解液の粘度、得られる電池の電気容量、電池出力などをバランスの取れたものとすることができる。   Examples of the solvent contained in the electrolytic solution 46 include the solvent used in the non-aqueous electrolytic solution. Examples of such a solvent include carbonates, esters, ethers, nitriles, furans, sulfolanes and dioxolanes, and these can be used alone or in combination. Specifically, as carbonates, cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, ethyl-n-butyl carbonate, methyl-t. -Chain carbonates such as -butyl carbonate, di-i-propyl carbonate, t-butyl-i-propyl carbonate, cyclic esters such as γ-butyl lactone and γ-valerolactone, methyl formate, methyl acetate, ethyl acetate, Chain esters such as methyl butyrate, ethers such as dimethoxyethane, ethoxymethoxyethane and diethoxyethane, nitriles such as acetonitrile and benzonitrile, tetrahydrofuran Furans such as orchid and methyltetrahydrofuran; sulfolanes such as sulfolane and tetramethylsulfolane; and dioxolanes such as 1,3-dioxolane and methyldioxolane. Of these, a combination of cyclic carbonates and chain carbonates is preferable. According to this combination, not only the cycle characteristics showing the battery characteristics in repeated charging and discharging are excellent, but also the viscosity of the electrolytic solution, the electric capacity of the obtained battery, the battery output, etc. can be balanced. it can.

液状電極４０は、さらに導電材を含むものとしてもよい。導電材としては、多孔質電極２０で説明したものを適宜用いることができる。導電材の平均粒径は、例えば、０．０２μｍ以上が好ましく０．０５μｍ以上がより好ましく、０．２μｍ以下が好ましく０．１μｍ以下がより好ましい。このような範囲では、流動性がよい。導電材の添加量は、液状電極４０の全体の体積に対して５体積％以上が好ましく１０体積％以上がより好ましく、３０体積％以下が好ましく２０体積％以下がより好ましい。このような範囲では、電池容量の低下を抑制し、導電性を十分に付与することができる。   The liquid electrode 40 may further include a conductive material. As the conductive material, those described for the porous electrode 20 can be appropriately used. The average particle diameter of the conductive material is, for example, preferably 0.02 μm or more, more preferably 0.05 μm or more, preferably 0.2 μm or less, and more preferably 0.1 μm or less. In such a range, the fluidity is good. The added amount of the conductive material is preferably 5% by volume or more, more preferably 10% by volume or more, more preferably 30% by volume or less, and more preferably 20% by volume or less with respect to the entire volume of the liquid electrode 40. In such a range, a decrease in battery capacity can be suppressed and conductivity can be sufficiently imparted.

二次電池１０では、多孔質電極２０と液状電極４０と絶縁膜３０とで構成された電極複合体１５などが、図示しない電池ケースに収容されている。電極複合体１５の一端には、正極タブ２８が絶縁層２９を介して設けられ、他端には負極タブ４８が絶縁層４９を介して設けられ、正極タブ２８の少なくとも一部及び負極タブ４８の少なくとも一部が外部と導通可能に構成されている。絶縁層２９は、正極タブ２８と液状電極４０との接触による短絡を防止するものである。絶縁層２９の内部では、正極タブ２８と多孔質集電体２２とが接続しており、正極タブ２８と多孔質電極２０とが導通している。絶縁層２９としては、少なくとも負極活物質４４が通過できない程度に緻密な材料を用いることができ、緻密な絶縁樹脂などを用いることができる。絶縁層４９は、負極タブ４８と多孔質電極２０との接触による短絡を防止するものである。絶縁層４９の内部には液状電極４０が存在しており、負極タブ４８と液状電極４０とが導通している。絶縁層４９としては、少なくとも負極活物質４４が通過できる程度の空隙を有する材料や筒状の材料などを用いることができ、絶縁樹脂製の多孔体や筒などを用いることができる。電池ケースは、多孔質電極２０と液状電極４０とが短絡しないような材質であればよいが、収容物を保護できる強度を有するものがより好ましい。電池ケースの材質としては、例えば、絶縁樹脂や、絶縁樹脂コーティングをした金属などとしてもよい。二次電池１０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、角型などとすることができる。   In the secondary battery 10, the electrode composite body 15 including the porous electrode 20, the liquid electrode 40, and the insulating film 30 is housed in a battery case (not shown). A positive electrode tab 28 is provided on one end of the electrode composite 15 via an insulating layer 29, and a negative electrode tab 48 is provided on the other end via an insulating layer 49. At least a part of the positive electrode tab 28 and the negative electrode tab 48 are provided. At least a part of which is configured to be able to conduct to the outside. The insulating layer 29 prevents a short circuit due to contact between the positive electrode tab 28 and the liquid electrode 40. Inside the insulating layer 29, the positive electrode tab 28 and the porous current collector 22 are connected, and the positive electrode tab 28 and the porous electrode 20 are electrically connected. As the insulating layer 29, a dense material that does not allow at least the negative electrode active material 44 to pass can be used, and a dense insulating resin or the like can be used. The insulating layer 49 prevents a short circuit due to contact between the negative electrode tab 48 and the porous electrode 20. The liquid electrode 40 exists inside the insulating layer 49, and the negative electrode tab 48 and the liquid electrode 40 are electrically connected. As the insulating layer 49, a material having a void that allows at least the negative electrode active material 44 to pass, a tubular material, or the like can be used, and a porous body or a tubular body made of an insulating resin can be used. The battery case may be made of any material that does not cause short circuit between the porous electrode 20 and the liquid electrode 40, but it is more preferable that the battery case has a strength capable of protecting the contents. The material of the battery case may be, for example, an insulating resin or a metal coated with an insulating resin. The shape of the secondary battery 10 is not particularly limited, but may be, for example, a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, a square type, or the like.

次に、二次電池１０の製造例について説明する。二次電池１０の製法は、例えば、（ａ）多孔質集電体２２の孔表面にこの孔を塞がないように活物質層２６を形成して多孔質電極２０を作製する工程と、（ｂ）多孔質電極２０の孔表面にこの孔の空隙が残るように絶縁膜３０を形成する工程と、（ｃ）絶縁膜３０が形成された多孔質電極２０の先ほどの空隙に液状電極４０を充填する工程と、を含む。   Next, a manufacturing example of the secondary battery 10 will be described. The manufacturing method of the secondary battery 10 includes, for example, (a) a step of forming the active material layer 26 on the surface of the pores of the porous current collector 22 so as not to close the pores, and manufacturing the porous electrode 20 ( b) a step of forming the insulating film 30 on the surface of the pores of the porous electrode 20 so that the voids of the holes remain, and (c) the liquid electrode 40 is placed in the former void of the porous electrode 20 on which the insulating film 30 is formed. And a filling step.

工程（ａ）では、正極活物質２４と導電材と結着材とを、適当な分散媒を加えて混合して正極スラリーを作製し、この正極スラリーを多孔質集電体２２の表面に塗布・乾燥して活物質層２６を形成してもよい。分散媒としては、例えばＮ−メチルピロリドン、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、分散媒としては、水に分散剤、増粘剤等を加え、ＳＢＲなどのラテックスを加えたものとしてもよい。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。塗布方法としては、例えば、正極スラリーに多孔質集電体２２を浸漬させて引き上げる方法（ディップ法）や、正極スラリーを多孔質集電体２２の上方からかけ流す方法や、正極スラリーを多孔質集電体２２の一端から供給し、他端から吸引する方法などが挙げられる。   In the step (a), the positive electrode active material 24, the conductive material, and the binder are added and mixed with an appropriate dispersion medium to prepare a positive electrode slurry, and the positive electrode slurry is applied to the surface of the porous current collector 22. The active material layer 26 may be formed by drying. As the dispersion medium, for example, an organic solvent such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N, N-dimethylaminopropylamine, ethylene oxide or tetrahydrofuran can be used. it can. As the dispersion medium, water may be added with a dispersant, a thickener, etc., and a latex such as SBR may be added. As the thickener, for example, polysaccharides such as carboxymethyl cellulose and methyl cellulose can be used alone or as a mixture of two or more kinds. Examples of the coating method include a method of immersing the porous current collector 22 in the positive electrode slurry and pulling it up (dip method), a method of pouring the positive electrode slurry from above the porous current collector 22, or a method of applying the positive electrode slurry to the porous body. A method of supplying from one end of the current collector 22 and sucking from the other end thereof may be mentioned.

工程（ｂ）では、絶縁膜３０の原料を含む溶液を多孔質電極２０の表面に塗布・乾燥して絶縁膜３０を形成してもよい。塗布方法としては、工程（ａ）と同様の方法が挙げられる。絶縁膜３０がポリマーの場合、絶縁膜３０の原料を塗布したのちに、重合させてもよい。   In the step (b), the insulating film 30 may be formed by applying and drying a solution containing the raw material of the insulating film 30 on the surface of the porous electrode 20. As the coating method, the same method as in step (a) can be mentioned. When the insulating film 30 is a polymer, the raw material of the insulating film 30 may be applied and then polymerized.

工程（ｃ）では、絶縁膜３０が形成された多孔質電極２０を液状電極４０に浸漬させて、多孔質電極２０の空隙に液状電極４０を充填してもよい。このとき、さらに真空引きを行ってもよい。浸漬は、電池ケース内で行ってもよいし、電池ケースの外で行ってもよいし、両方を組み合わせてもよい。   In the step (c), the porous electrode 20 on which the insulating film 30 is formed may be immersed in the liquid electrode 40 to fill the voids of the porous electrode 20 with the liquid electrode 40. At this time, vacuuming may be further performed. The immersion may be performed inside the battery case, outside the battery case, or a combination of both.

以上説明した二次電池１０では、多孔質集電体２２の孔表面に正極活物質２４を含む活物質層２６が形成されている。多孔質集電体２２は、平板状の集電体などに比して比表面積が大きいため、活物質を形成するのに必要な所定の表面積を確保する際、集電体自体の体積を小さくできる。また、多孔質集電体２２では、集電体の全体が三次元的に導通しているため、複数の集電体を接続する構成などが必要なく、集電構造を簡略化・小体積化できる。こうして、集電体を含む集電構造の簡略化・小体積化が可能となり、その分だけ活物質の充填率を高めることができる。特に、電池を大型化させる場合（例えば車載用途など）には、充填率をより高めることができる。また、多孔質電極２０の空隙に負極活物質４４を含む液状電極４０が充填されるため、多孔質電極２０の空隙を利用して活物質の充填率を高めることができる。このように、活物質の充填率を高めることができるため、電池容量をより高めることができる。また、正極活物質２４を備えた多孔質電極２０と負極活物質４４を含む液状電極４０とが絶縁膜３０を介して至近距離に配置されており、電荷のキャリアであるイオンの移動距離が短いため、イオン伝導抵抗を低減でき、出力低下を抑制できる。また、多孔質電極２０では、比表面積の大きい多孔質集電体２２の孔表面に正極活物質２４が形成されているため、活物質の充填率が高くても多孔質集電体２２と正極活物質２４との接触面積を大きくすることができる。このため、多孔質集電体２２と正極活物質２４との間の電子伝導経路が良好に形成され、活物質の容量を無駄なく取り出すことができ、電池容量を高めることができる。   In the secondary battery 10 described above, the active material layer 26 containing the positive electrode active material 24 is formed on the pore surface of the porous current collector 22. Since the porous current collector 22 has a larger specific surface area than a flat plate current collector or the like, the volume of the current collector itself is reduced when securing a predetermined surface area necessary for forming the active material. it can. Further, in the porous current collector 22, since the whole current collector is three-dimensionally conducted, there is no need to connect a plurality of current collectors, and the current collection structure is simplified and the volume is reduced. it can. In this way, the current collecting structure including the current collector can be simplified and reduced in volume, and the filling rate of the active material can be increased accordingly. In particular, when increasing the size of the battery (for example, in-vehicle use), the filling rate can be further increased. Further, since the liquid electrode 40 containing the negative electrode active material 44 is filled in the voids of the porous electrode 20, it is possible to increase the filling rate of the active material by utilizing the voids of the porous electrode 20. In this way, the filling rate of the active material can be increased, so that the battery capacity can be further increased. Further, the porous electrode 20 provided with the positive electrode active material 24 and the liquid electrode 40 containing the negative electrode active material 44 are arranged in close proximity to each other with the insulating film 30 interposed therebetween, and the migration distance of ions, which are charge carriers, is short. Therefore, the ion conduction resistance can be reduced and the output reduction can be suppressed. Further, in the porous electrode 20, since the positive electrode active material 24 is formed on the pore surface of the porous current collector 22 having a large specific surface area, even if the filling rate of the active material is high, the porous current collector 22 and the positive electrode are positive. The contact area with the active material 24 can be increased. Therefore, the electron conduction path between the porous current collector 22 and the positive electrode active material 24 is favorably formed, the capacity of the active material can be taken out without waste, and the battery capacity can be increased.

また、二次電池１０では、多孔質電極２０が正極であるため、電池容量を高める効果がより大きい。というのも、正極活物質には電子伝導性の低いものが多く、そうしたものでは、集電体と活物質との間の電子伝導経路が良好に形成されていないと、活物質の容量を十分に取り出せないことがある。しかし、二次電池１０では、多孔質集電体２２の孔表面に正極活物質２４が形成されているため、上述したように電子伝導経路が良好に形成され、活物質の容量を無駄なく取り出すことができるからである。   Moreover, in the secondary battery 10, since the porous electrode 20 is the positive electrode, the effect of increasing the battery capacity is greater. This is because many positive electrode active materials have a low electron conductivity, and in such a material, if the electron conduction path between the current collector and the active material is not well formed, the capacity of the active material will not be sufficient. It may not be possible to retrieve it. However, in the secondary battery 10, since the positive electrode active material 24 is formed on the surface of the pores of the porous current collector 22, the electron conduction path is well formed as described above, and the capacity of the active material is taken out without waste. Because you can.

また、二次電池１０では、液状電極４０が負極であるため、電池容量を高める効果がより大きい。というのも、負極活物質には電子伝導性の高いものが多く、電子伝導性の高い負極活物質４４を含む液状電極４０では導電材を添加する必要がないため、活物質の充填率をより高めることができるからである。また、負極活物質には、充放電時の体積変化が大きいものが多いが、二次電池１０では、液状電極４０が負極であるため、負極活物質４４の体積変化の影響を受けにくい。   Further, in the secondary battery 10, since the liquid electrode 40 is the negative electrode, the effect of increasing the battery capacity is greater. This is because many negative electrode active materials have high electron conductivity, and it is not necessary to add a conductive material to the liquid electrode 40 containing the negative electrode active material 44 having high electron conductivity, so that the filling rate of the active material can be increased. This is because it can be increased. Many negative electrode active materials have a large volume change during charging and discharging, but in the secondary battery 10, since the liquid electrode 40 is the negative electrode, the negative electrode active material 44 is less likely to be affected by the volume change.

また、二次電池１０では、三次元的に全体が導通している多孔質集電体２２を用いることにより、複数の集電体が必要な積層型に比して集電構造を簡略化できるし、捲回型や積層型に比して薄膜作製や捲回、積層などの工程がなく製造工程を簡略化できるため、製造コストを低減できる。   Further, in the secondary battery 10, by using the porous current collector 22 which is three-dimensionally electrically conductive as a whole, the current collecting structure can be simplified as compared with the laminated type in which a plurality of current collectors are required. However, as compared with the wound type and the laminated type, the manufacturing process can be simplified because there are no thin film forming, winding, and laminating processes, and thus the manufacturing cost can be reduced.

なお、本発明は上述した実施形態に何ら限定されることはなく、本発明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 invention is not limited to the above-described embodiment and can be implemented in various modes within the technical scope of the present invention.

例えば、上述した実施形態では、リチウムイオン二次電池について説明したが、これに限定されない。例えば、稼働イオン種はリチウムイオンに限定されず、ナトリウムイオンやカリウムイオンなどのアルカリ金属イオンとしてもよいし、カルシウムイオンやマグネシウムイオンなどのアルカリ土類金属イオンとしてもよい。   For example, in the above-described embodiment, the lithium ion secondary battery has been described, but the present invention is not limited to this. For example, the working ion species is not limited to lithium ions, and may be alkali metal ions such as sodium ions and potassium ions, or alkaline earth metal ions such as calcium ions and magnesium ions.

上述した実施形態では、多孔質電極を正極とし、液状電極を負極としたが、多孔質電極を負極とし、液状電極を正極としてもよい。   Although the porous electrode is the positive electrode and the liquid electrode is the negative electrode in the above-described embodiment, the porous electrode may be the negative electrode and the liquid electrode may be the positive electrode.

上述した実施形態では、液状電極は、支持塩を含む電解液に活物質を分散させたものとしたが、これに限定されない。例えば、支持塩としてのイオン液体に活物質を分散させたものとしてもよい。また、固体活物質と固体支持塩とを混合することにより常温（例えば２０℃）以下で液状化した混合溶融液体としてもよい。固体活物質としては、例えば、２，２，６，６−テトラメチルピペリジン−１−オキシル（ＴＥＭＰＯ）や４−メトキシ−２，２，６，６−テトラメチルピペリジン−１−オキシル（ＭｅＯ−ＴＥＭＰＯ）などの、ＴＥＭＰＯ系ラジカル化合物が挙げられる。また、固体支持塩としては、例えば、ビス（トリフルオロメタンスルホニル）イミド（ＬｉＴＦＳＩ）やビス（ペンタフルオロエタンスルホニル）イミド（ＬｉＢＥＴＩ）などの、フルオロアルキルスルホニル部位を有する金属塩が挙げられる。   In the above-described embodiment, the liquid electrode is the one in which the active material is dispersed in the electrolytic solution containing the supporting salt, but the liquid electrode is not limited to this. For example, an active material may be dispersed in an ionic liquid serving as a supporting salt. Alternatively, a mixed molten liquid that is liquefied at room temperature (for example, 20 ° C.) or lower by mixing the solid active material and the solid supporting salt may be used. Examples of the solid active material include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MeO-TEMPO). ) And other TEMPO-based radical compounds. In addition, examples of the solid supporting salt include metal salts having a fluoroalkylsulfonyl moiety such as bis (trifluoromethanesulfonyl) imide (LiTFSI) and bis (pentafluoroethanesulfonyl) imide (LiBETI).

上述した実施形態では、電極複合体の一端には、正極タブが絶縁層を介して設けられ、他端には負極タブが絶縁層を介して設けられているものとしたが、こうしたものに限定されない。例えば、後述の図２に示すように、正極タブと液状電極とを両者が接触しないように配置してその間の絶縁層を省略してもよいし、負極タブと多孔質電極とを両者が接触しないように配置してその間の絶縁層を省略してもよい。   In the above-described embodiment, the positive electrode tab is provided at one end of the electrode composite through the insulating layer, and the negative electrode tab is provided at the other end through the insulating layer. However, the present invention is not limited to this. Not done. For example, as shown in FIG. 2 described later, the positive electrode tab and the liquid electrode may be arranged so that they do not contact each other, and the insulating layer between them may be omitted, or the negative electrode tab and the porous electrode may contact each other. The insulating layer may be omitted so that the insulating layer therebetween may be omitted.

次に、本発明の二次電池を作製した例について、実施例として説明する。実施例では、図２に示す二次電池６０を作製して評価を行った。図２では、ラミネート袋６２の内部を透視した状態を示した。図２の左側の全体図において、活物質層７６と記した矩形の領域は、活物質層７６が多孔質集電体７２の孔表面に形成された領域を示し、絶縁膜８０と記した矩形の領域は、絶縁膜８０が多孔質正極７０または多孔質集電体７２の孔表面に形成された領域を示した。なお、本発明は、以下の実施例に何ら限定されることはなく、本発明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。   Next, an example of producing the secondary battery of the present invention will be described as an example. In the example, the secondary battery 60 shown in FIG. 2 was manufactured and evaluated. FIG. 2 shows a state in which the inside of the laminated bag 62 is seen through. In the overall view on the left side of FIG. 2, a rectangular area denoted by the active material layer 76 indicates an area in which the active material layer 76 is formed on the surface of the pores of the porous current collector 72 and is denoted by an insulating film 80. The region of (2) indicates a region where the insulating film 80 is formed on the surface of the hole of the porous positive electrode 70 or the porous current collector 72. Needless to say, the present invention is not limited to the following examples and can be carried out in various modes within the technical scope of the present invention.

（多孔質正極７０の作製）
正極活物質７４として層状岩塩型構造を有するＬｉ（Ｎｉ1/3Ｍｎ1/3Ｃｏ1/3）Ｏ2（粒径約５．０μｍ）を９０．５質量％、導電材としてアセチレンブラックを８．０質量％、及び、バインダーとしてＰＶｄＦを１．５質量％含む正極合材を、適量の分散媒（Ｎ−メチル−２−ピロリドン）を用いて混合し、正極スラリーを得た。この正極スラリーを、網目構造のＮｉ金属発泡体（住友電工製のセルメット、品番＃６）である５×５×３５ｍｍの多孔質集電体７２のうちの、５×５×２０ｍｍの部分にディップ法により塗布・乾燥して活物質層７６を形成し、多孔質正極７０を作製した。活物質層７６の厚みは５０μｍであった。活物質層７６には、０．７２ｇの正極合材が含まれていた。つづいて、多孔質正極７０のうち活物質層７６の形成されていない多孔質集電体部分にＮｉ製の正極タブ７８を溶接した。 (Production of Porous Positive Electrode 70)
90.5% by mass of Li (Ni 1/3 Mn 1/3 Co 1/3 ) O 2 (particle size: about 5.0 μm) having a layered rock salt structure as the positive electrode active material 74, and acetylene black 8 as a conductive material. A positive electrode mixture containing 0.0% by mass and 1.5% by mass of PVdF as a binder was mixed with an appropriate amount of a dispersion medium (N-methyl-2-pyrrolidone) to obtain a positive electrode slurry. This positive electrode slurry is dipped in a 5 × 5 × 20 mm portion of a 5 × 5 × 35 mm porous current collector 72, which is a mesh-shaped Ni metal foam (Celmet manufactured by Sumitomo Electric, product number # 6). Then, the active material layer 76 was formed by coating and drying by a method to prepare a porous positive electrode 70. The thickness of the active material layer 76 was 50 μm. The active material layer 76 contained 0.72 g of the positive electrode mixture. Subsequently, a positive electrode tab 78 made of Ni was welded to the porous current collector portion of the porous positive electrode 70 where the active material layer 76 was not formed.

（絶縁膜８０の形成）
得られた多孔質正極７０の表面に、ＶｄＦ−ＨＦＰの共重合体を含むスラリーを、ディップ法により塗布・乾燥して、絶縁膜８０を形成した。絶縁膜８０の膜厚は、モデル実験などから、２〜１０μｍ程度と推察された。絶縁膜８０が形成された多孔質電極７０を、放射光を線源に用いたＣＴにより観察したところ、多孔質電極７０の孔の空隙が約６０体積％残っていることが確認された。 (Formation of insulating film 80)
On the surface of the obtained porous positive electrode 70, a slurry containing a VdF-HFP copolymer was applied and dried by a dipping method to form an insulating film 80. The film thickness of the insulating film 80 was estimated to be about 2 to 10 μm from model experiments. When the porous electrode 70 on which the insulating film 80 was formed was observed by CT using radiated light as a radiation source, it was confirmed that about 60% by volume of voids remained in the pores of the porous electrode 70.

（液状負極９０の作製）
エチレンカーボネートとジエチルカーボネートとを体積比３：７で混合した混合溶媒に、ＬｉＰＦ6を２ｍｏｌ／Ｌとなるように溶解して電解液９６を調製した。得られた電解液９６に負極活物質９４としての人造黒鉛粉末（粒径約１０μｍ）を懸濁させ、スラリー状の液状負極９０を得た。液状負極９０において、負極活物質９４の濃度は６５質量％とした。 (Production of Liquid Negative Electrode 90)
An electrolyte solution 96 was prepared by dissolving LiPF 6 in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 3: 7 so as to be 2 mol / L. An artificial graphite powder (particle size: about 10 μm) as a negative electrode active material 94 was suspended in the obtained electrolytic solution 96 to obtain a liquid negative electrode 90 in a slurry form. In the liquid negative electrode 90, the concentration of the negative electrode active material 94 was 65% by mass.

（二次電池６０の作製）
絶縁膜８０が形成された多孔質正極７０を液状負極９０に浸漬させ、さらに真空引きすることにより、液状負極９０を多孔質正極７０の空隙に充填して電極複合体６５を作製した。このとき、絶縁膜８０には、液状負極９０の一部の電解液９６が含浸され、ゲルポリマー電解質となる。続いて、この電極複合体６５を若干の余剰液状負極９０と共にアルミラミネート袋６２に挿入し、さらに集電体を兼ねるＮｉ製の負極タブ９８を液状負極９０と接触するように挿入し、熱溶着によって密封した。この二次電池６０には、０．５５ｇの負極活物質９４が含まれていた。 (Production of Secondary Battery 60)
The porous positive electrode 70 on which the insulating film 80 was formed was dipped in the liquid negative electrode 90 and further evacuated to fill the voids of the liquid positive electrode 90 into the voids of the porous positive electrode 70 to produce the electrode composite 65. At this time, the insulating film 80 is impregnated with a part of the electrolytic solution 96 of the liquid negative electrode 90 and becomes a gel polymer electrolyte. Then, this electrode composite 65 is inserted into the aluminum laminate bag 62 together with a little excess liquid negative electrode 90, and a Ni negative electrode tab 98 also serving as a current collector is inserted so as to be in contact with the liquid negative electrode 90, and heat welding is performed. Sealed by. The secondary battery 60 contained 0.55 g of the negative electrode active material 94.

（充放電試験）
作製した二次電池６０を用いて、３．０−４．２Ｖの範囲で、０．２Ｃ（１６ｍＡ）の定電流充放電試験を実施した。その結果、初回の放電容量として７６．６ｍＡｈが得られ、活物質層７６が形成された部位の多孔質正極サイズ換算で４６５Ｗｈ／Ｌという高エネルギー密度を実現できた。市販のリチウム二次電池のエネルギー密度は、２００〜４００Ｗｈ／Ｌ程度が一般的であるが、実施例では、そうしたものに比してエネルギー密度（電池容量）を高めることができ、また、従来のシート対向型電池（上述した捲回型や積層型など）で同容量のものと比較すると出力の低下を抑制できることがわかった。 (Charge / discharge test)
Using the produced secondary battery 60, a constant current charge / discharge test of 0.2 C (16 mA) was performed in the range of 3.0 to 4.2V. As a result, 76.6 mAh was obtained as the initial discharge capacity, and a high energy density of 465 Wh / L in terms of the size of the porous positive electrode in the portion where the active material layer 76 was formed could be realized. The energy density of a commercially available lithium secondary battery is generally about 200 to 400 Wh / L, but in the embodiment, the energy density (battery capacity) can be increased as compared with that, and in addition to the conventional It was found that the sheet facing type battery (such as the wound type or the laminated type described above) can suppress the decrease in output as compared with the one having the same capacity.

本発明は、電池産業の分野に利用可能である。   The present invention can be used in the field of battery industry.

１０ 二次電池、１５ 電極複合体、２０ 多孔質電極、２２ 多孔質集電体、２４ 正極活物質、２６ 活物質層、２８ 正極タブ、２９ 絶縁層、３０ 絶縁膜、４０ 液状電極、４４ 負極活物質、４６ 電解液、４８ 負極タブ、４９ 絶縁層、６０ 二次電池、６２ ラミネート袋、６５ 電極複合体、７０ 多孔質正極、７２ 多孔質集電体、７４ 正極活物質、７６ 活物質層、７８ 正極タブ、８０ 絶縁膜、９０ 液状負極、９４ 負極活物質、９６ 電解液、９８ 負極タブ。   10 secondary battery, 15 electrode composite, 20 porous electrode, 22 porous current collector, 24 positive electrode active material, 26 active material layer, 28 positive electrode tab, 29 insulating layer, 30 insulating film, 40 liquid electrode, 44 negative electrode Active material, 46 electrolytic solution, 48 negative electrode tab, 49 insulating layer, 60 secondary battery, 62 laminated bag, 65 electrode composite, 70 porous positive electrode, 72 porous current collector, 74 positive electrode active material, 76 active material layer , 78 positive electrode tab, 80 insulating film, 90 liquid negative electrode, 94 negative electrode active material, 96 electrolytic solution, 98 negative electrode tab.

Claims (8)

多孔質集電体と、正極活物質及び負極活物質のうちの一方の活物質を含み前記多孔質集電体の孔表面に形成された活物質層と、を有する多孔質電極と、
前記多孔質電極の孔表面に該孔の空隙が残るように形成されたイオン伝導性の絶縁膜と、
前記正極活物質及び前記負極活物質のうちの他方の活物質と支持塩とを含み、前記絶縁膜が形成された前記多孔質電極の前記空隙に充填された液状電極と、
を備えた、二次電池。 Porous current collector, a porous electrode having an active material layer formed on the surface of the pores of the porous current collector containing one active material of the positive electrode active material and the negative electrode active material,
An ion conductive insulating film formed so that voids of the pores remain on the surface of the pores of the porous electrode,
A liquid electrode containing the other active material of the positive electrode active material and the negative electrode active material and a supporting salt, and filled in the voids of the porous electrode in which the insulating film is formed,
A secondary battery equipped with. 前記多孔質集電体は、１０μｍ以上２０００μｍ以下の空隙が三次元的に連結した多孔体である、請求項１に記載の二次電池。   The secondary battery according to claim 1, wherein the porous current collector is a porous body in which voids of 10 μm or more and 2000 μm or less are three-dimensionally connected. 前記多孔質集電体は、５０μｍ以上６００μｍ以下の空隙が三次元的に連結した多孔体である、請求項１又は２に記載の二次電池。   The secondary battery according to claim 1, wherein the porous current collector is a porous body in which voids of 50 μm or more and 600 μm or less are three-dimensionally connected. 前記活物質層は、厚みが５μｍ以上１０００μｍ以下である、請求項１〜３のいずれか１項に記載の二次電池。   The secondary battery according to claim 1, wherein the active material layer has a thickness of 5 μm or more and 1000 μm or less. 前記活物質層は、厚みが２５μｍ以上２５０μｍ以下である、請求項１〜４のいずれか１項に記載の二次電池。   The secondary battery according to claim 1, wherein the active material layer has a thickness of 25 μm or more and 250 μm or less. 前記多孔質集電体は、金属製もしくは炭素製である、請求項１〜５のいずれか１項に記載の二次電池。   The secondary battery according to claim 1, wherein the porous current collector is made of metal or carbon. 前記多孔質集電体は、網目構造、ジャイロイド構造、逆オパール構造、ファイバー構造からなる群より選ばれる１以上の構造を有している、請求項１〜６のいずれか１項に記載の二次電池。   7. The porous current collector according to claim 1, wherein the porous current collector has one or more structures selected from the group consisting of a mesh structure, a gyroid structure, an inverse opal structure, and a fiber structure. Secondary battery. 前記液状電極は、電解液に粉末状の前記他方の活物質を分散させたものである、請求項１〜７のいずれか１項に記載の二次電池。   The secondary battery according to claim 1, wherein the liquid electrode is obtained by dispersing the other active material in powder form in an electrolytic solution.
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