JP2013131465A - INTERMEDIATE PRODUCT METAL SHEET FOR Sn-Cu ALLOY ACTIVE MATERIAL LAYER SUPPORTED ELECTRODE MEMBER - Google Patents

INTERMEDIATE PRODUCT METAL SHEET FOR Sn-Cu ALLOY ACTIVE MATERIAL LAYER SUPPORTED ELECTRODE MEMBER Download PDF

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JP2013131465A
JP2013131465A JP2011281894A JP2011281894A JP2013131465A JP 2013131465 A JP2013131465 A JP 2013131465A JP 2011281894 A JP2011281894 A JP 2011281894A JP 2011281894 A JP2011281894 A JP 2011281894A JP 2013131465 A JP2013131465 A JP 2013131465A
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coating layer
copper
active material
layer
thickness
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Osamu Majima
将 真嶋
Takao Tsujimura
太佳夫 辻村
Takahiro Fujii
孝浩 藤井
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Nippon Steel Nisshin Co Ltd
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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
    • 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
    • Y02E60/13—Energy storage using capacitors

Abstract

PROBLEM TO BE SOLVED: To provide a material suitable for forming a negative electrode which can accommodate an increase in battery capacity of a lithium ion secondary battery and lithium ion capacitor, and hardly causes a decrease in battery capacity due to repeated charge/discharge cycles and a deterioration in battery performance caused by insufficient strength of a collector.SOLUTION: An intermediate product metal sheet for an Sn-Cu alloy active material layer supported electrode member includes a copper coated layer at least on one side surface of a steel sheet, and a tin coated layer on the copper coated layer. The copper coated layer is in contact with the tin coated layer. When a thickness of the steel sheet is denoted as t, a thickness of the copper coated layer per one side surface is denoted as t, a thickness of the tin coated layer is denoted as t, and a total thickness of the sheets including each of the coated layers is denoted as t, tis in a range of 3-100 μm and t/t is 0.20 or more, and tis in a range of 0.5-10.0 μm and t/tis in a range of 0.5-2.5 on the same surface side.

Description

本発明は、熱処理に供することによってＳｎ−Ｃｕ合金活物質を表面に有する電極部材が得られる、中間製品金属シートに関する。   The present invention relates to an intermediate product metal sheet from which an electrode member having a Sn—Cu alloy active material on its surface can be obtained by subjecting it to a heat treatment.

従来リチウムイオン二次電池の負極活物質には黒鉛やハードカーボンなどの炭素系活物質が広く適用されている。しかし、炭素系活物質の理論容量は３７０ｍＡｈ／ｇ程度であり、実用電池の容量は理論容量をほとんど限界まで使用している。そこで、電池の更なる大容量化を実現するために、充電時にＬｉと合金化することで大きな容量を発揮する合金系活物質の適用が検討されている。そのような合金系活物質として錫および錫合金が挙げられる。   Conventionally, carbon-based active materials such as graphite and hard carbon have been widely used as negative electrode active materials for lithium ion secondary batteries. However, the theoretical capacity of the carbon-based active material is about 370 mAh / g, and the capacity of the practical battery uses the theoretical capacity almost to the limit. Therefore, in order to realize a further increase in capacity of the battery, application of an alloy-based active material that exhibits a large capacity by alloying with Li during charging has been studied. Examples of such alloy-based active materials include tin and tin alloys.

単体金属の錫は充放電時のリチウムイオンの吸蔵および脱離に伴う体積変化が炭素系活物質よりも大きい。そのため充放電を繰り返すことにより活物質自体の崩壊や基板（集電体）からの剥離が生じやすく、電池寿命が短くなるという欠点がある。この体積変化を緩和する手法として錫を他の金属（Ｃｕ、Ｃｏ、Ｎｉなど）と合金化させて錫合金とし、これを負極に用いることが有効である。   The single metal tin has a larger volume change with the insertion and extraction of lithium ions during charge and discharge than the carbon-based active material. For this reason, there is a drawback that the active material itself is easily collapsed or peeled off from the substrate (current collector) by repeating charge and discharge, and the battery life is shortened. As a technique for mitigating this volume change, it is effective to alloy tin with other metals (Cu, Co, Ni, etc.) to form a tin alloy, which is used for the negative electrode.

特許文献１には銅箔からなる集電体上に錫または錫合金からなる活物質層を溶融めっき法、スパッタ法、真空蒸着法により形成したのち熱処理して、活物質層と集電体を相溶させた負極が開示されている。特許文献２には高強度な銅合金箔からなる集電体と錫または錫合金からなる活物質層を有する負極が開示されている。   In Patent Document 1, an active material layer made of tin or a tin alloy is formed on a current collector made of copper foil by a hot dipping method, a sputtering method, or a vacuum deposition method, and then heat-treated to form an active material layer and a current collector. A compatible negative electrode is disclosed. Patent Document 2 discloses a negative electrode having a current collector made of a high-strength copper alloy foil and an active material layer made of tin or a tin alloy.

特開２００３−３６８４０号公報JP 2003-36840 A 特開２０００−３０３１２８号公報JP 2000-303128 A

銅箔を芯材としてその表面に錫合金の活物質層を形成させる場合、合金化のための熱処理過程で芯材の銅が軟化し、強度が低下してしまうという問題がある。芯材の強度が低下すると電池の充放電に伴う活物質の体積変化によって芯材が塑性変形して、電極部材である集電体としての初期の形状を維持できなくなることがある。熱処理による軟化の影響が少ない場合であっても銅箔は本来的に強度レベルが低いため、錫層の製膜時に生じた膜応力によって集電体が変形することがある。このように集電体の形状が所定の設計形状から逸脱すると、電池内でのセルの状態が不均一となり、電池性能に悪影響が生じる。   When a copper foil is used as a core material and a tin alloy active material layer is formed on the surface thereof, there is a problem that the copper of the core material is softened during the heat treatment process for alloying and the strength is lowered. When the strength of the core material is reduced, the core material may be plastically deformed due to the volume change of the active material accompanying charging / discharging of the battery, and the initial shape of the current collector as the electrode member may not be maintained. Even when the influence of softening by heat treatment is small, the strength of the copper foil is inherently low, and the current collector may be deformed by the film stress generated when the tin layer is formed. Thus, when the shape of the current collector deviates from the predetermined design shape, the state of the cells in the battery becomes non-uniform, and the battery performance is adversely affected.

本発明は、リチウムイオン二次電池やリチウムイオンキャパシタの電池容量増大に対応でき、かつ充放電の繰り返しによる電池容量の低下や集電体の強度不足に起因した電池性能の低下を起こしにくい負極を構築するのに適した材料を提供しようというものである。   The present invention provides a negative electrode that can cope with an increase in the battery capacity of a lithium ion secondary battery or a lithium ion capacitor and is less likely to cause a decrease in battery performance due to repeated charge / discharge or a lack of strength of the current collector. It is intended to provide materials suitable for construction.

上記目的は、鋼シートの少なくとも片側表面に、銅被覆層を有し、その上に錫被覆層を有し、前記銅被覆層と前記錫被覆層は接しており、鋼シートの厚さをｔS、片面当たりの銅被覆層の厚さをｔCu、錫被覆層の厚さをｔSn、各被覆層を含めたシートのトータル厚さをｔとするとき、ｔS：３〜１００μｍ、ｔS／ｔ：０.２０以上、ｔSn：０.５〜１０.０μｍであり、かつ同一表面側においてｔSn／ｔCu：０.５〜２.５であるＳｎ−Ｃｕ合金活物質層担持電極部材用の中間製品金属シートによって達成される。 The object is to have a copper coating layer on at least one surface of the steel sheet, and have a tin coating layer thereon, the copper coating layer and the tin coating layer are in contact with each other, and the thickness of the steel sheet is t S , where the thickness of the copper coating layer per side is t Cu , the thickness of the tin coating layer is t Sn , and the total thickness of the sheet including each coating layer is t, t S : 3 to 100 μm, t S / t: 0.20 or more, t Sn : 0.5 to 10.0 μm, and Sn Sn / t Cu : 0.5 to 2.5 on the same surface side. This is achieved by an intermediate product metal sheet for electrode members.

前記Ｓｎ−Ｃｕ合金活物質は、具体的にはリチウムイオン二次電池またはリチウムイオンキャパシタの負極活物質として機能するものである。   Specifically, the Sn—Cu alloy active material functions as a negative electrode active material of a lithium ion secondary battery or a lithium ion capacitor.

本発明に従う金属シートは、熱処理に供することによって表層部にＳｎ−Ｃｕ合金活物質層が担持された電極部材（集電体など）とすることができる。芯材に鋼シートを使用しているため従来の銅箔芯材のように熱処理で軟化しない。得られた電極部材は高強度であるため充放電に伴って活物質層の体積変化が生じても塑性変形しない。すなわち、繰り返し充放電を行っても当該電極部材は活物質の膨張収縮に追従して均一に弾性変形するため、活物質の脱落や剥離が抑止される。また、本発明に従う金属シートは銅被覆層と錫被覆層の膜厚が適性化されているので、充放電に伴う体積変化の激しい金属Ｓｎ層の残存が抑えられ、そのことも充放電挙動の安定化につながる。このようなことから本発明はリチウムイオン二次電池の電池容量の向上に有利とされるＳｎ−Ｃｕ合金活物質を備えた負極において、その長寿命化に寄与するものである。   The metal sheet according to the present invention can be used as an electrode member (current collector or the like) having an Sn—Cu alloy active material layer supported on the surface layer portion by subjecting it to a heat treatment. Since a steel sheet is used for the core material, it is not softened by heat treatment unlike conventional copper foil core materials. Since the obtained electrode member has high strength, it does not undergo plastic deformation even if the volume of the active material layer changes with charge / discharge. That is, even if charging / discharging is repeated, the electrode member is elastically deformed uniformly following the expansion and contraction of the active material, so that the active material is prevented from falling off or peeling off. In addition, since the thickness of the copper coating layer and the tin coating layer of the metal sheet according to the present invention is optimized, it is possible to suppress the remaining of the metal Sn layer that undergoes a large volume change due to charge / discharge, which also indicates the charge / discharge behavior. It leads to stabilization. For this reason, the present invention contributes to extending the life of the negative electrode including the Sn—Cu alloy active material, which is advantageous for improving the battery capacity of the lithium ion secondary battery.

本発明の金属シートの断面構造を模式的に示した図。The figure which showed typically the cross-section of the metal sheet of this invention. 銅以外の下地めっき層を有する本発明の金属シートの断面構造を模式的に示した図。The figure which showed typically the cross-section of the metal sheet of this invention which has foundation | substrate plating layers other than copper. 本発明に従う中間製品の金属シートを熱処理することによって得られる電極部材の断面構造を模式的に示した図。The figure which showed typically the cross-section of the electrode member obtained by heat-processing the metal sheet of the intermediate product according to this invention. 銅以外の下地めっき層を有するタイプの本発明に従う中間製品の金属シート（図２参照）を熱処理することによって得られる電極部材の断面構造を模式的に示した図。The figure which showed typically the cross-section of the electrode member obtained by heat-treating the metal sheet (refer FIG. 2) of the intermediate product according to this invention of the type which has base plating layers other than copper. 錫めっき層の量が過剰である中間製品の金属シートを熱処理することによって得られる電極部材の断面構造を模式的に示した図。The figure which showed typically the cross-sectional structure of the electrode member obtained by heat-processing the metal sheet of the intermediate | middle product in which the quantity of a tin plating layer is excess.

図１に、本発明の金属シートの断面構造を模式的に示す。鋼シート１を芯材として、その表面に銅被覆層２を有し、さらにその上に錫被覆層３を有することにより金属シート１０が構成されている。銅被覆層２と錫被覆層３は接触している。これらの被覆層は電極として作用させる側の表面に形成されていればよい。この図では、鋼シート１の両面に均等に銅被覆層２と錫被覆層３を形成した場合を例示してある。この金属シート１０はＳｎ−Ｃｕ合金活物質を有する電極部材を得るための中間製品である。すなわち、この金属シート１０を所定温度で熱処理すれば、銅被覆層２と錫被覆層３の間で拡散が進行して、Ｓｎ−Ｃｕ活物質層を備えた電極部材となる。銅被覆層２と錫被覆層３からなる積層構造は、Ｓｎ−Ｃｕ合金活物質を得るための「前駆体」であると言うことができる。   FIG. 1 schematically shows a cross-sectional structure of the metal sheet of the present invention. A metal sheet 10 is configured by using a steel sheet 1 as a core material, a copper coating layer 2 on the surface, and a tin coating layer 3 thereon. The copper coating layer 2 and the tin coating layer 3 are in contact. These coating layers should just be formed in the surface of the side made to act as an electrode. In this figure, the case where the copper coating layer 2 and the tin coating layer 3 are formed equally on both surfaces of the steel sheet 1 is illustrated. This metal sheet 10 is an intermediate product for obtaining an electrode member having a Sn—Cu alloy active material. That is, if this metal sheet 10 is heat-treated at a predetermined temperature, diffusion proceeds between the copper coating layer 2 and the tin coating layer 3 and an electrode member provided with an Sn—Cu active material layer is obtained. It can be said that the laminated structure composed of the copper coating layer 2 and the tin coating layer 3 is a “precursor” for obtaining an Sn—Cu alloy active material.

図２に、銅以外の下地めっき層を有する本発明の金属シートの断面構造を模式的に示す。後述するように銅被覆層２を形成するための手段として電気銅めっき法が好適に利用できるが、芯材である鋼シートがステンレス鋼の場合などは銅めっきの密着性を確保するために下地めっきとしてニッケルめっきを施しておくことが有効である。そのような場合、鋼シート１と銅被覆層の間にはニッケル等の下地めっき層４が介在して構わない。   FIG. 2 schematically shows a cross-sectional structure of the metal sheet of the present invention having a base plating layer other than copper. As will be described later, an electrolytic copper plating method can be suitably used as a means for forming the copper coating layer 2. However, when the steel sheet as the core material is stainless steel, the base is used to ensure the adhesion of the copper plating. It is effective to apply nickel plating as plating. In such a case, a base plating layer 4 such as nickel may be interposed between the steel sheet 1 and the copper coating layer.

図３に、本発明に従う中間製品の金属シートを熱処理することによって得られる電極部材の断面構造を模式的に示す。芯材である鋼シート１の表面にはＳｎ−Ｃｕ合金活物質層５が形成され、電極部材２０を構成している。Ｓｎ−Ｃｕ合金活物質層５は図１に示した銅被覆層２と錫被覆層３との間で拡散が進行することによって形成された層であり、主として金属間化合物Ｃｕ6Ｓｎ5およびＣｕ3Ｓｎからなる。鋼シート１とＳｎ−Ｃｕ合金活物質層５の間には、上記の金属間化合物の生成に余剰となった銅被覆層２が残留している。図１に示した銅被覆層２と錫被覆層３の量比によって残留する銅被覆層２の厚さは変わってくる。銅被覆層２の残留は必ずしも必要ないが、逆に錫被覆層３が最表層に多量に残留すると、金属Ｓｎ活物質は充放電時の体積変化が大きいことから、電池寿命の向上を阻害する要因となる。したがって、錫被覆層３よりも銅被覆層２の方が過剰となるようにそれらの量比を設定することが望ましい。また、Ｓｎ−Ｃｕ合金活物質層５の下地に銅被覆層２がある程度残留すると、充放電を繰り返したときの電池容量の低下が緩和される傾向にある。 FIG. 3 schematically shows a cross-sectional structure of an electrode member obtained by heat-treating an intermediate product metal sheet according to the present invention. An Sn—Cu alloy active material layer 5 is formed on the surface of the steel sheet 1 as a core material, and constitutes an electrode member 20. The Sn—Cu alloy active material layer 5 is a layer formed by diffusion between the copper coating layer 2 and the tin coating layer 3 shown in FIG. 1, and is mainly composed of intermetallic compounds Cu 6 Sn 5 and Cu. 3 It consists of Sn. Between the steel sheet 1 and the Sn—Cu alloy active material layer 5, there remains a copper coating layer 2 that is excessive for the production of the intermetallic compound. The thickness of the remaining copper coating layer 2 varies depending on the quantity ratio of the copper coating layer 2 and the tin coating layer 3 shown in FIG. The copper coating layer 2 does not necessarily remain, but conversely, if the tin coating layer 3 remains in a large amount on the outermost layer, the metal Sn active material has a large volume change during charge / discharge, which hinders improvement in battery life. It becomes a factor. Therefore, it is desirable to set the quantity ratio thereof so that the copper coating layer 2 becomes excessive rather than the tin coating layer 3. Moreover, when the copper coating layer 2 remains to some extent on the base of the Sn—Cu alloy active material layer 5, there is a tendency that a decrease in battery capacity when charging / discharging is repeated is alleviated.

図４に、銅以外の下地めっき層を有するタイプの本発明に従う中間製品の金属シート（図２参照）を熱処理することによって得られる電極部材の断面構造を模式的に示す。この場合は、下地めっき層４（例えばニッケル）はＳｎ−Ｃｕ合金活物質の生成反応にはほとんど関与することなく、ほぼそのまま残留する。このタイプの電極部材２０の構造は、下地めっき層４が残留していることを除き、上記図３の場合と基本的に同じである。   FIG. 4 schematically shows a cross-sectional structure of an electrode member obtained by heat-treating a metal sheet (see FIG. 2) of an intermediate product according to the present invention having a base plating layer other than copper. In this case, the base plating layer 4 (for example, nickel) remains almost as it is without being substantially involved in the formation reaction of the Sn—Cu alloy active material. The structure of this type of electrode member 20 is basically the same as in the case of FIG. 3 except that the base plating layer 4 remains.

図５に、錫めっき層の量が過剰である中間製品の金属シートを熱処理することによって得られる電極部材の断面構造を模式的に示す。この場合、電極部材２０の最表層に錫被覆層３が残留する。錫被覆層３の若干の残留は許容されることが多いが、残留量が多くなると前述のように充放電時における金属Ｓｎ活物質の体積変化が大きいことに起因して電池寿命が短くなるので、好ましくない。   FIG. 5 schematically shows a cross-sectional structure of an electrode member obtained by heat-treating an intermediate product metal sheet in which the amount of the tin plating layer is excessive. In this case, the tin coating layer 3 remains on the outermost layer of the electrode member 20. In some cases, a slight residual amount of the tin coating layer 3 is allowed. However, if the residual amount increases, the battery life is shortened due to the large volume change of the metal Sn active material during charge and discharge as described above. It is not preferable.

〔鋼シート〕
本発明に従う金属シートの芯材である鋼シートは、電極部材（集電体など）を構成した際の強度を担う。鋼シート厚さが薄すぎると芯材としての強度が不充分となり、充放電時の活物質層の体積変化によって不均一に塑性変形する場合がある。検討の結果、鋼シートの厚さｔSは３μｍ以上とすることが望まれる。５μｍ以上とすることがより好ましい。一方、鋼シートが厚すぎると電池やキャパシタ内で電極材料の占める体積が過剰となり、電池またはキャパシタの単位体積当たりの容量が十分に稼げないので、１００μｍ以下とすることが好ましく、５０μｍ以下、あるいは３０μｍ以下に管理してもよい。 [Steel sheet]
The steel sheet which is a core material of the metal sheet according to the present invention bears strength when an electrode member (current collector or the like) is configured. If the steel sheet thickness is too thin, the strength as a core material becomes insufficient, and plastic deformation may occur unevenly due to the volume change of the active material layer during charge and discharge. As a result of the study, it is desirable that the thickness t S of the steel sheet be 3 μm or more. More preferably, it is 5 μm or more. On the other hand, if the steel sheet is too thick, the volume occupied by the electrode material in the battery or capacitor becomes excessive, and the capacity per unit volume of the battery or capacitor cannot be sufficiently obtained. Therefore, the thickness is preferably 100 μm or less, or 50 μm or less, or You may manage to 30 micrometers or less.

鋼シート厚さｔS自体が適正であっても、金属シートに占める鋼シート厚さの割合が少なすぎると、活物質層の体積変化に弾性限度内で追随するに足る剛性が確保できない。種々検討の結果、中間製品である金属シートのトータル厚さｔに占める鋼シート厚さｔSの割合ｔS／ｔは０.２以上とする必要がある。それより小さいと芯材に銅箔を用いている従来材に対する強度的な優位性が十分に発揮されない。ｔS／ｔは０.３以上とすることがより好ましい。銅被覆層および錫被覆層の厚さが後述の規定を満たす限り、ｔS／ｔの上限は特に定める必要がないが、通常、ｔS／ｔは０.９以下の範囲で設定すればよい。 Even if the steel sheet thickness t S itself is appropriate, if the ratio of the steel sheet thickness to the metal sheet is too small, the rigidity sufficient to follow the volume change of the active material layer within the elastic limit cannot be secured. As a result of various studies, the ratio t S / t of the steel sheet thickness t S to the total thickness t of the intermediate product metal sheet needs to be 0.2 or more. If it is smaller than that, the strength advantage over the conventional material using copper foil as the core material is not sufficiently exhibited. More preferably, t S / t is 0.3 or more. As long as the thicknesses of the copper coating layer and the tin coating layer satisfy the regulations described later, the upper limit of t S / t does not need to be particularly defined, but usually, t S / t may be set within a range of 0.9 or less. .

鋼種としては、普通鋼の他、各種ステンレス鋼が適用できる。規格製品を例示すれば、普通鋼の場合、例えばＪＩＳ Ｇ３１４１：２００９に規定される冷延鋼板（鋼帯を含む）が挙げられる。ステンレス鋼の場合、例えばＪＩＳ Ｇ４３０５：２００５に規定されるフェライト系またはオーステナイト系の化学組成を有する鋼板（鋼帯を含む）が適用できる。   As a steel type, various stainless steels can be applied besides ordinary steel. As an example of a standard product, in the case of plain steel, for example, a cold-rolled steel sheet (including a steel strip) defined in JIS G3141: 2009 can be mentioned. In the case of stainless steel, for example, a steel plate (including a steel strip) having a ferritic or austenitic chemical composition defined in JIS G4305: 2005 can be applied.

鋼シートに適用できる普通鋼、フェライト系ステンレス鋼、オーステナイト系ステンレス鋼の具体的な成分組成を以下に例示する。
（１）普通鋼
質量％で、Ｃ：０.００１〜０.１５％、Ｓｉ：０.００１〜０.１％、Ｍｎ：０.００５〜０.６％、Ｐ：０.００１〜０.０５％、Ｓ：０.００１〜０.５％、Ａｌ：０.００１〜０.５％、Ｎｉ：０.００１〜１.０％、Ｃｒ：０.００１〜１.０％、Ｃｕ：０〜０.１％、Ｔｉ：０〜０.５％、Ｎｂ：０〜０.５％、Ｎ：０〜０.０５％、残部Ｆｅおよび不可避的不純物。 Specific component compositions of ordinary steel, ferritic stainless steel, and austenitic stainless steel applicable to the steel sheet are exemplified below.
(1) Normal steel In mass%, C: 0.001 to 0.15%, Si: 0.001 to 0.1%, Mn: 0.005 to 0.6%, P: 0.001 to 0.00. 05%, S: 0.001 to 0.5%, Al: 0.001 to 0.5%, Ni: 0.001 to 1.0%, Cr: 0.001 to 1.0%, Cu: 0 -0.1%, Ti: 0-0.5%, Nb: 0-0.5%, N: 0-0.05%, balance Fe and inevitable impurities.

（２）フェライト系ステンレス鋼
質量％で、Ｃ：０.０００１〜０.１５％、Ｓｉ：０.００１〜１.２％、Ｍｎ：０.００１〜１.２％、Ｐ：０.００１〜０.０４％、Ｓ：０.０００５〜０.０３％、Ｎｉ：０〜０.６％、Ｃｒ：１１.５〜３２.０％、Ｍｏ：０〜２.５％、Ｃｕ：０〜１.０％、Ｎｂ：０〜１.０％、Ｔｉ：０〜１.０％、Ａｌ：０〜０.２％、Ｎ：０〜０.０２５％、Ｂ：０〜０.０１％、Ｖ：０〜０.５％、Ｗ：０〜０.３％、Ｃａ、Ｍｇ、Ｙ、ＲＥＭ（希土類元素）の合計：０〜０.１％、残部Ｆｅおよび不可避的不純物。 (2) Ferritic stainless steel In mass%, C: 0.0001 to 0.15%, Si: 0.001 to 1.2%, Mn: 0.001 to 1.2%, P: 0.001 0.04%, S: 0.0005 to 0.03%, Ni: 0 to 0.6%, Cr: 11.5 to 32.0%, Mo: 0 to 2.5%, Cu: 0 to 1 0.0%, Nb: 0 to 1.0%, Ti: 0 to 1.0%, Al: 0 to 0.2%, N: 0 to 0.025%, B: 0 to 0.01%, V : 0-0.5%, W: 0-0.3%, Ca, Mg, Y, REM (rare earth elements) total: 0-0.1%, the balance Fe and inevitable impurities.

（３）オーステナイト系ステンレス鋼
質量％で、Ｃ：０.０００１〜０.１５％、Ｓｉ：０.００１〜４.０％、Ｍｎ：０.００１〜２.５％、Ｐ：０.００１〜０.０４５％、Ｓ：０.０００５〜０.０３％、Ｎｉ：６.０〜２８.０％、Ｃｒ：１５.０〜２６.０％、Ｍｏ：０〜７.０％、Ｃｕ：０〜３.５％、Ｎｂ：０〜１.０％、Ｔｉ：０〜１.０％、Ａｌ：０〜０.１％、Ｎ：０〜０.３％、Ｂ：０〜０.０１％、Ｖ：０〜０.５％、Ｗ：０〜０.３％、Ｃａ、Ｍｇ、Ｙ、ＲＥＭ（希土類元素）の合計：０〜０.１％、残部Ｆｅおよび不可避的不純物。
ここで、下限が０％である元素は任意元素である。 (3) Austenitic stainless steel in mass%, C: 0.0001 to 0.15%, Si: 0.001 to 4.0%, Mn: 0.001 to 2.5%, P: 0.001 0.045%, S: 0.0005 to 0.03%, Ni: 6.0 to 28.0%, Cr: 15.0 to 26.0%, Mo: 0 to 7.0%, Cu: 0 -3.5%, Nb: 0-1.0%, Ti: 0-1.0%, Al: 0-0.1%, N: 0-0.3%, B: 0-0.01% , V: 0 to 0.5%, W: 0 to 0.3%, Ca, Mg, Y, REM (rare earth elements) total: 0 to 0.1%, remaining Fe and inevitable impurities.
Here, the element whose lower limit is 0% is an arbitrary element.

〔銅被覆層〕
銅被覆層は、後述の錫被覆層とともに、Ｓｎ−Ｃｕ合金活物質を生成させるための前駆体として機能する。片面当たりの銅被覆層の平均厚さｔCuは、後述のｔSn／ｔCuを満たす限り特に規定しなくてよいが、通常、１.０〜８.０μｍの範囲で設定すればよい。銅被覆層の形成方法としては、電気銅めっき法、クラッド法、気相めっき法（例えばスパッタリング、イオンプレーティング）などが挙げられる。このうち、電気銅めっき法、クラッド法は大量生産現場での実用的な手法として好適である。 (Copper coating layer)
A copper coating layer functions as a precursor for producing | generating a Sn-Cu alloy active material with the tin coating layer mentioned later. The average thickness t Cu of the copper coating layer per one side does not have to be specified as long as t Sn / t Cu described later is satisfied, but it is usually set within a range of 1.0 to 8.0 μm. Examples of the method for forming the copper coating layer include an electrolytic copper plating method, a cladding method, and a vapor phase plating method (for example, sputtering and ion plating). Among these, the electrolytic copper plating method and the clad method are suitable as practical methods at a mass production site.

電気銅めっき法は公知の手法が採用できる。例えば硫酸浴を用いた電気銅めっき法の場合、硫酸銅：２００〜２５０ｇ／Ｌ、硫酸：３０〜７５ｇ／Ｌ、液温：２０〜５０℃のめっき浴を用いて、陰極電流密度：１〜２０Ａ／ｄｍ2とする条件が例示できる。 A known technique can be adopted as the electrolytic copper plating method. For example, in the case of an electrolytic copper plating method using a sulfuric acid bath, a cathode current density of 1 to 1 is obtained using a plating bath of copper sulfate: 200 to 250 g / L, sulfuric acid: 30 to 75 g / L, and liquid temperature: 20 to 50 ° C. The condition of 20 A / dm 2 can be exemplified.

〔下地めっき層〕
電気銅めっきを施す場合は、鋼シート表面と銅めっき層の密着性を向上させるために、予め鋼シート表面に下地めっき層を形成させておくことが有効な場合がある。例えば鋼シートがステンレス鋼の場合、下地めっきとしてニッケルストライクめっきを施すことが効果的である。この場合、図２に示したように、銅被覆層の下に銅以外の下地めっき層が介在することとなる。 [Underplating layer]
When performing electrolytic copper plating, in order to improve the adhesion between the steel sheet surface and the copper plating layer, it may be effective to form a base plating layer on the steel sheet surface in advance. For example, when the steel sheet is stainless steel, it is effective to perform nickel strike plating as the base plating. In this case, as shown in FIG. 2, a base plating layer other than copper is interposed under the copper coating layer.

ニッケルストライクめっきの条件は、例えば、塩化ニッケル：２３０〜２５０ｇ／Ｌ、塩酸：１２５ｍｌ／Ｌ、ｐＨ：１〜１.５の常温のめっき浴を用いて、陰極電流密度：１〜１０Ａ／ｄｍ2とすることができる。 The conditions of nickel strike plating are, for example, a normal temperature plating bath of nickel chloride: 230 to 250 g / L, hydrochloric acid: 125 ml / L, pH: 1 to 1.5, and cathode current density: 1 to 10 A / dm 2. It can be.

一方、鋼シートが普通鋼の場合など、下地めっきとして銅ストライクめっきを施しておくことが効果的なこともある。銅ストライクめっきは、その上に施す電気銅めっき（本めっき）と同種の金属を付着させるものであるから、この場合は、銅ストライクめっき層と電気銅めっき（本めっき）層によって銅被覆層が構成される。したがって、銅ストライクめっき層と電気銅めっき（本めっき）層の合計厚さが、片面当たりの銅被覆層厚さｔCuに相当する。 On the other hand, when the steel sheet is plain steel, it may be effective to perform copper strike plating as the base plating. In copper strike plating, the same kind of metal as the electro copper plating (main plating) applied thereon is adhered. In this case, the copper coating layer is formed by the copper strike plating layer and the electro copper plating (main plating) layer. Composed. Therefore, the total thickness of the copper strike plating layer and the electrolytic copper plating (main plating) layer corresponds to the copper coating layer thickness t Cu per side.

銅ストライクめっきの条件は、例えば、ピロリン酸銅：６５〜１０５ｇ／Ｌ、ピロリン酸カリウム：２４０〜４５０ｇ／Ｌ、全銅イオン濃度（ｇ／Ｌ）に対する全ピロリン酸塩イオン濃度（ｇ／Ｌ）の比（Ｐ比）：６.４〜８.０、アンモニア水：１〜６ｍＬ／Ｌ、液温：５０〜６０℃、ｐＨ：８.２〜９.２のめっき浴を用いて、陰極電流密度：１〜７Ａ／ｄｍ2とすることができる。 The conditions for copper strike plating are, for example, copper pyrophosphate: 65-105 g / L, potassium pyrophosphate: 240-450 g / L, total pyrophosphate ion concentration (g / L) relative to total copper ion concentration (g / L) Ratio (P ratio): 6.4 to 8.0, aqueous ammonia: 1 to 6 mL / L, liquid temperature: 50 to 60 ° C., pH: 8.2 to 9.2, cathode current density: it can be 1~7A / dm 2.

〔錫被覆層〕
本発明に従う金属シートは、上記の銅被覆層の上に、錫被覆層を有する。これら銅被覆層と錫被覆層は互いに接しており、これら２層は熱処理に供することによってＳｎ−Ｃｕ合金活物質層を生成させるためのＳｎおよびＣｕ供給源となる。したがって、錫被覆層は銅被覆層と共に、Ｓｎ−Ｃｕ合金活物質の前駆体として機能する。 [Tin coating layer]
The metal sheet according to the present invention has a tin coating layer on the copper coating layer. The copper coating layer and the tin coating layer are in contact with each other, and these two layers serve as Sn and Cu supply sources for generating a Sn—Cu alloy active material layer by being subjected to heat treatment. Therefore, the tin coating layer functions as a precursor of the Sn—Cu alloy active material together with the copper coating layer.

錫被覆層の厚さが薄すぎると熱処理によって形成されるＳｎ−Ｃｕ合金活物質の厚さも薄くなり、現存の炭素系活物質を用いた負極を上回る単位面積当たりの容量を実現することができない。検討の結果、錫被覆層の片面当たりの平均厚さｔSnは０.５μｍ以上を確保する必要がある。０.７μｍ以上、あるいは１.０μｍ以上に管理してもよい。一方、錫被覆層の平均厚さが過剰になると、熱処理による拡散を利用してＳｎ−Ｃｕ合金の金属間化合物を十分に生成させることが難しくなる場合がある。その場合、表層部（銅被覆層から遠い部分）に充放電時の体積変化が大きい金属Ｓｎ層が残存し、電池寿命の向上を阻害する要因となる。発明者らの検討によれば、片面当たりの錫被覆層厚さｔSnは１０.０μｍ以下とすることが望まれる。７.０μｍ以下、あるいは５.０μｍ以下に管理してもよい。 If the thickness of the tin coating layer is too thin, the thickness of the Sn—Cu alloy active material formed by the heat treatment also becomes thin, and the capacity per unit area exceeding the negative electrode using the existing carbon-based active material cannot be realized. . As a result of the study, it is necessary to secure an average thickness t Sn per one side of the tin coating layer of 0.5 μm or more. You may manage to 0.7 micrometer or more, or 1.0 micrometer or more. On the other hand, when the average thickness of the tin coating layer is excessive, it may be difficult to sufficiently generate an intermetallic compound of the Sn—Cu alloy by utilizing diffusion by heat treatment. In that case, a metal Sn layer having a large volume change at the time of charging / discharging remains in the surface layer portion (portion far from the copper coating layer), which becomes a factor that hinders improvement in battery life. According to the study by the inventors, it is desired that the tin coating layer thickness t Sn per side is 10.0 μm or less. You may manage to 7.0 micrometers or less, or 5.0 micrometers or less.

錫被覆層の形成方法としては公知の各種錫めっき法が利用できる。例えば、電気めっき法、溶融めっき法、化学めっき法（例えば無電解めっき法）、気相めっき法（例えばスパッタリング、イオンプレーティングなど）が挙げられる。なかでも電気錫めっき法は比較的高速かつ経済的にめっき層を形成させることができ、かつめっき厚さのコントロールも容易であることから、大量生産に適している。錫被覆層厚さを特に厚くしたい場合には溶融錫めっき法が適している。クラッド法によって錫被覆層を形成させてもよい。   Various known tin plating methods can be used as a method for forming the tin coating layer. For example, electroplating method, hot dipping method, chemical plating method (for example, electroless plating method), vapor phase plating method (for example, sputtering, ion plating, etc.) can be mentioned. In particular, the electrotin plating method is suitable for mass production because it can form a plating layer relatively quickly and economically and it is easy to control the plating thickness. When it is desired to increase the thickness of the tin coating layer, the hot-dip tin plating method is suitable. A tin coating layer may be formed by a cladding method.

電気錫めっきの条件は、例えば、硫酸第一錫：３０〜５０ｇ／Ｌ、硫酸：４０〜８０ｇ／Ｌ、クレゾールスルホン酸：３０〜６０ｇ／Ｌ、ゼラチン：１〜３ｇ／Ｌ、β−ナフトール：０.５〜１ｇ／Ｌ、液温：１５〜２５℃のめっき浴を用いて、陰極電流密度：０.５〜５Ａ／ｄｍ2とすることができる。 The conditions for electrotin plating are, for example, stannous sulfate: 30-50 g / L, sulfuric acid: 40-80 g / L, cresolsulfonic acid: 30-60 g / L, gelatin: 1-3 g / L, β-naphthol: Using a plating bath of 0.5 to 1 g / L and liquid temperature of 15 to 25 ° C., the cathode current density can be set to 0.5 to 5 A / dm 2 .

〔錫被覆層と銅被覆層の厚さ比ｔSn／ｔCu〕
錫被覆層と銅被覆層は互いに接触して積層することにより、Ｓｎ−Ｃｕ合金活物質の前駆体として機能する。そのＳｎ−Ｃｕ合金活物質層は主として金属間化合物Ｃｕ6Ｓｎ5およびＣｕ3Ｓｎにより構成されるものとなるが、Ｓｎ含有率の高いＣｕ6Ｓｎ5の方が単位重量あたりの充放電容量が高いため、Ｃｕ6Ｓｎ5が電極の表層側にできるだけ多量に形成されることが望ましい。中間製品の金属シートにおいて銅被覆層の上に錫被覆層を形成させる積層順序とすることによって表層側にＣｕ6Ｓｎ5を有するＳｎ−Ｃｕ合金活物質層が得られる。 [Thickness ratio of tin coating layer and copper coating layer t Sn / t Cu ]
The tin coating layer and the copper coating layer function as a precursor of the Sn—Cu alloy active material by laminating in contact with each other. Its Sn-Cu alloy active material layer is assumed to be mainly composed of intermetallic compound Cu 6 Sn 5 and Cu 3 Sn, the charge-discharge capacity per person is unit weight of high Cu 6 Sn 5 with Sn content Since it is high, it is desirable that Cu 6 Sn 5 is formed as much as possible on the surface layer side of the electrode. An Sn—Cu alloy active material layer having Cu 6 Sn 5 on the surface layer side is obtained by adopting a lamination order in which a tin coating layer is formed on a copper coating layer in a metal sheet of an intermediate product.

金属Ｓｎ自体は活物質として機能するものの、充放電に伴う体積変化が大きいため、熱処理によって形成される活物質層の表層部に錫被覆層ができるだけ残存しないようにすることが電池寿命の向上に有利となる。発明者らの検討によれば、錫被覆層と銅被覆層の厚さ比ｔSn／ｔCuを２.５以下とすることによって、熱処理後に表層部に残存する錫被覆層をほぼ消失させることが可能となる。熱処理条件によっては若干の錫被覆層の残存が見られることもあるが、電池寿命を阻害しない程度に抑制することができる。ただし、ｔSn自体の厚さが過剰であると錫被覆層の表層部付近まで銅原子が十分に拡散しきれない場合もあるので、ｔSnは上述の規定に従う膜厚範囲とすることが前提となる。ｔSn／ｔCuは２.０以下であることがより好ましい。 Although the metal Sn itself functions as an active material, the volume change accompanying charging / discharging is large, so that the tin coating layer does not remain as much as possible in the surface layer portion of the active material layer formed by heat treatment to improve the battery life. It will be advantageous. According to the study by the inventors, the thickness ratio t Sn / t Cu between the tin coating layer and the copper coating layer is set to 2.5 or less so that the tin coating layer remaining on the surface layer portion is substantially eliminated after the heat treatment. Is possible. Although some tin coating layer may remain depending on the heat treatment conditions, it can be suppressed to such an extent that the battery life is not impaired. However, since t Sn copper atoms to the vicinity of the surface layer portion thickness is excessive and the tin coating layer itself may not be sufficiently diffused, t Sn is assumed that the thickness range according to the provisions of the above It becomes. t Sn / t Cu is more preferably 2.0 or less.

一方、ｔSn／ｔCuが小さくなるとＳｎ−Ｃｕ合金活物質層の下に活物質として機能しない銅被覆層が残存するようになる。また、Ｓｎ−Ｃｕ合金活物質層中においてはＣｕ6Ｓｎ5より単位重量あたりの充放電容量の小さいＣｕ3Ｓｎの存在割合が多くなる。熱処理後にこれらの層が多量に存在するような過剰な銅被覆層の形成は不経済である。検討の結果、ｔSn／ｔCuを０.５以上とすることが望ましく、０.７以上、あるいは１.０以上に管理してもよい。 On the other hand, when t Sn / t Cu becomes small, a copper coating layer that does not function as an active material remains under the Sn—Cu alloy active material layer. In the Sn—Cu alloy active material layer, the proportion of Cu 3 Sn having a smaller charge / discharge capacity per unit weight than Cu 6 Sn 5 increases. It is uneconomical to form an excess copper coating layer in which these layers are present in large amounts after heat treatment. As a result of the study, t Sn / t Cu is preferably set to 0.5 or more, and may be controlled to 0.7 or more, or 1.0 or more.

〔金属シートの製造工程〕
本発明に従う中間製品の金属シート（本発明品）は、例えば以下のような工程で製造できる。［ ］内は材料形態を示す。（ ）は必要に応じて採用する工程を示す。脱脂・洗浄等の中間工程は記載を省略してある。
（ａ）［鋼シート］→圧延→［箔状鋼シート］→（下地めっき）→電気銅めっき→電気錫めっき→（圧延）→［本発明品］
（ｂ）［鋼シート］→（下地めっき）→電気銅めっき→電気錫めっき→圧延→［本発明品］
（ｃ）［鋼シート］→銅シートとのクラッド圧延→電気錫めっき→（圧延）→［本発明品］
（ｄ）［鋼シート］→（下地めっき）→電気銅めっき→錫シートとのクラッド圧延→［本発明品］
（ｅ）［鋼シート］→銅シートおよび錫シートとのクラッド圧延→［本発明品］ [Manufacturing process of metal sheet]
The intermediate product metal sheet according to the present invention (product of the present invention) can be produced, for example, by the following steps. [] Shows the material form. () Indicates a process to be adopted as necessary. The description of intermediate processes such as degreasing and washing is omitted.
(A) [Steel sheet] → Rolling → [Foiled steel sheet] → (Under plating) → Electro copper plating → Electro tin plating → (Roll) → [Invention product]
(B) [Steel sheet] → (Under plating) → Electro copper plating → Electro tin plating → Rolling → [Product of the present invention]
(C) [Steel sheet] → Clad rolling with copper sheet → Electro tin plating → (Rolling) → [Invention product]
(D) [Steel sheet] → (Undercoat) → Electro copper plating → Clad rolling with tin sheet → [Invention product]
(E) [Steel sheet] → Clad rolling with copper sheet and tin sheet → [Invention product]

〔熱処理〕
本発明に従う中間製品の金属シートは、熱処理に供することによって表面にＳｎ−Ｃｕ合金活物質を有する電極部材となる。熱処理方法は赤外線加熱、誘導加熱など公知の種々の加熱方法が採用できる。電極部材表面の酸化を防ぐために真空中あるいは不活性ガス雰囲気中での熱処理が好ましい。熱処理条件は金属シートの表面温度が例えば１８０〜２１０℃となる状態で１５〜３０ｈ保持する条件が適用できる。 〔Heat treatment〕
The metal sheet of the intermediate product according to the present invention becomes an electrode member having a Sn—Cu alloy active material on the surface by being subjected to heat treatment. As the heat treatment method, various known heating methods such as infrared heating and induction heating can be adopted. In order to prevent oxidation of the electrode member surface, heat treatment in a vacuum or in an inert gas atmosphere is preferable. As a heat treatment condition, a condition of holding for 15 to 30 hours in a state where the surface temperature of the metal sheet is 180 to 210 ° C. can be applied.

〔リチウムイオン二次電池への適用〕
熱処理を終えて得られた電極部材はリチウムイオン二次電池やリチウムイオンキャパシタの負極集電体として使用される。各負極集電体はセパレータを介して正極集電体と組み合わされて「電極積層体」とされ、電解液とともにリチウムイオン二次電池やリチウムイオンキャパシタを構成することとなる。 [Application to lithium ion secondary batteries]
The electrode member obtained after the heat treatment is used as a negative electrode current collector of a lithium ion secondary battery or a lithium ion capacitor. Each negative electrode current collector is combined with the positive electrode current collector via a separator to form an “electrode laminate”, and constitutes a lithium ion secondary battery or a lithium ion capacitor together with the electrolytic solution.

電解液を例示すると、溶媒としては例えば、エチレンカーボネート（ＥＣ）、ジエチルカーボネート（ＤＥＣ）、プロピレンカーボネート、ブチレンカーボネート、ジメチルカーボネート、スルホラン、ジメトキシエタン、テトラヒドロフラン、ジオキソランなどの非水溶媒が挙げられ、これらを単独で使用してもよいし２種以上を混合して使用してもよい。溶質としては例えば、ＬｉＣｌＯ4、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＡｓＦ6、ＬｉＮ(ＣＦ3ＳＯ2)2、ＬｉＮ（Ｃ2Ｆ5ＳＯ2)2、ＬｉＮ(ＣＦ3ＳＯ2)(Ｃ4Ｆ9ＳＯ2)、ＬｉＣ(ＣＦ3ＳＯ2)3、ＬｉＣＦ3(ＣＦ2)3ＳＯ3などが挙げられ、これらを単独で使用してもよいし２種以上を混合して使用してもよい。 Examples of the electrolyte include non-aqueous solvents such as ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate, butylene carbonate, dimethyl carbonate, sulfolane, dimethoxyethane, tetrahydrofuran, and dioxolane. May be used singly or in combination of two or more. Examples of the solute include LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiC (CF 3 SO 2 ) 3 , LiCF 3 (CF 2 ) 3 SO 3 and the like may be used, and these may be used alone or in admixture of two or more.

《中間製品金属シートの作製》
芯材用の鋼板として、普通鋼、ＳＵＳ４３０、ＳＵＳ３０４の各冷延焼鈍鋼板（板厚０．１５ｍｍ、幅２００ｍｍ）を用意した。普通鋼は以下の化学組成を有するものである。
質量％で、Ｃ：０.００３％、Ａｌ：０.０３８％、Ｓｉ：０.００３％、Ｍｎ：０.１２％、Ｐ：０.０１２％、Ｓ：０.１２２％、Ｎｉ：０.０２％、Ｃｒ：０.０２％、Ｃｕ：０.０１％、Ｔｉ：０.０７３％、Ｎ：０.００２３％、残部Ｆｅおよび不可避的不純物。
ＳＵＳ４３０、ＳＵＳ３０４はいずれもＪＩＳ Ｇ４３０５：２００５相当の市販材である。 << Production of intermediate product metal sheet >>
As steel plates for the core material, cold rolled annealed steel plates (plate thickness 0.15 mm, width 200 mm) of ordinary steel, SUS430, and SUS304 were prepared. Normal steel has the following chemical composition.
In mass%, C: 0.003%, Al: 0.038%, Si: 0.003%, Mn: 0.12%, P: 0.012%, S: 0.122%, Ni: 0.1. 02%, Cr: 0.02%, Cu: 0.01%, Ti: 0.073%, N: 0.0027%, balance Fe and inevitable impurities.
Both SUS430 and SUS304 are commercially available materials corresponding to JIS G4305: 2005.

上記各鋼板について、連続式電気めっきラインにて下地めっき、電気銅めっき、および電気錫めっきを順次施し、その後、冷間圧延する工程（上述の（ｂ）に相当）により、鋼シートを芯材としてその表面に銅被覆層および錫被覆層を有する中間製品の金属シートを作製した。めっき付着量および冷間圧延率を調整することにより、鋼シートの厚さｔS、片面当たりの銅被覆層の厚さｔCu、および片面当たりの錫被覆層の厚さｔSnをコントロールした。なお、下地めっきは、普通鋼については銅ストライクめっきを、ＳＵＳ４３０およびＳＵＳ３０４についてはニッケルストライクめっきとした。銅ストライクめっき層の厚さは銅被覆層の厚さｔCuに含まれる。各層の厚さは表２中に示してある。 About each said steel plate, a steel sheet is made into a core material by the process (equivalent to the above-mentioned (b)) which performs base plating, electrolytic copper plating, and electrotin plating sequentially in a continuous electroplating line, and is then cold-rolled. An intermediate product metal sheet having a copper coating layer and a tin coating layer on its surface was prepared. The thickness t S of the steel sheet, the thickness t Cu of the copper coating layer per side, and the thickness t Sn of the tin coating layer per side were controlled by adjusting the plating adhesion amount and the cold rolling rate. The base plating was copper strike plating for ordinary steel, and nickel strike plating for SUS430 and SUS304. The thickness of the copper strike plating layer is included in the thickness t Cu of the copper coating layer. The thickness of each layer is shown in Table 2.

各電気めっきの具体的な条件は以下のとおりである。
〔銅ストライクめっき〕
ピロリン酸銅：７０ｇ／Ｌ、ピロリン酸カリウム：２５０ｇ／Ｌ、全銅イオン濃度（ｇ／Ｌ）に対する全ピロリン酸塩イオン濃度（ｇ／Ｌ）の比（Ｐ比）：８〜１０、液温：５５℃、ｐＨ：９のめっき浴を用いて、陰極電流密度：５Ａ／ｄｍ2の条件範囲で両面均等に行い、片面当たりのめっき付着量を０.３μｍとした。 Specific conditions for each electroplating are as follows.
[Copper strike plating]
Copper pyrophosphate: 70 g / L, potassium pyrophosphate: 250 g / L, ratio of total pyrophosphate ion concentration (g / L) to total copper ion concentration (g / L) (P ratio): 8-10, liquid temperature : Using a plating bath of 55 ° C. and pH: 9 with a cathode current density of 5 A / dm 2 , both surfaces were evenly formed, and the amount of plating deposited on one surface was 0.3 μm.

〔ニッケルストライクめっき〕
塩化ニッケル：２３０〜２５０ｇ／Ｌ、塩酸：１２５ｍｌ／Ｌ、ｐＨ：１〜１.５の常温のめっき浴を用いて、陰極電流密度：１〜１０Ａ／ｄｍ2の条件範囲で両面均等に行った。 [Nickel strike plating]
Using a plating bath at room temperature of nickel chloride: 230 to 250 g / L, hydrochloric acid: 125 ml / L, pH: 1 to 1.5, both surfaces were evenly processed in a condition range of cathode current density: 1 to 10 A / dm 2 . .

〔電気銅めっき（本めっき）〕
硫酸銅：２１０ｇ／Ｌ、硫酸：４５ｇ／Ｌ、液温：４０℃の銅めっき浴を用い、陰極電流密度：１０Ａ／ｄｍ2の条件範囲で両面均等に行った。 [Electro copper plating (main plating)]
Copper sulfate: 210 g / L, sulfuric acid: 45 g / L, liquid temperature: 40 ° C. A copper plating bath was used, and the both sides were uniformly applied in a condition range of cathode current density: 10 A / dm 2 .

比較用のために市販の銅板（板厚０.２ｍｍ）を用意し、その両側表面に上記の電気錫めっきを施したのち圧延して１０μｍ厚さの銅箔を芯材とする中間製品の金属シートを作製した。   For comparison purposes, a commercially available copper plate (thickness 0.2 mm) is prepared, and after applying the above-mentioned electrotin plating to both surfaces, it is rolled and the intermediate product metal having a 10 μm thick copper foil as the core material A sheet was produced.

《電極部材の作製》
各中間製品の金属シートに以下の熱処理を施し、一部の比較例を除きＳｎ−Ｃｕ合金活物質層を有する負極集電体用の電極部材を作製した。
〔熱処理〕
赤外線加熱炉にて真空中で材料表面温度が２００℃となるように２４ｈ保持した。 <Production of electrode member>
The metal sheet of each intermediate product was subjected to the following heat treatment, and an electrode member for a negative electrode current collector having a Sn—Cu alloy active material layer was produced except for some comparative examples.
〔Heat treatment〕
The material surface temperature was kept for 24 hours in an infrared heating furnace so that the material surface temperature was 200 ° C.

《芯材の強度確認試験》
上記各鋼板および銅板をそれぞれ１０μｍまで冷間圧延した試料、並びにそれらの試料を上記熱処理条件で熱処理した試料を別途作製し、電極部材の芯材としての強度を確認するために引張試験に供した。表１に、試験数ｎ＝１０で引張試験を行った場合の引張強さの平均値を示す。 《Core strength check test》
Samples obtained by cold rolling each steel plate and copper plate to 10 μm, and samples obtained by heat-treating these samples under the heat treatment conditions were separately prepared and subjected to a tensile test to confirm the strength of the electrode member as a core material. . Table 1 shows the average value of the tensile strength when the tensile test is performed with the number of tests n = 10.

Figure 2013131465
Figure 2013131465

表１に示されるように、鋼シート（普通鋼、ＳＵＳ４３０およびＳＵＳ３０４）は２００℃での熱処理による軟化がほとんどないことがわかる。すなわち、鋼シートを芯材としてＳｎ−Ｃｕ合金活物質層を形成した場合には、銅箔を芯材とする場合と比べ、極めて強度の高い電極部材が得られることが確認された。   As shown in Table 1, it can be seen that the steel sheets (regular steel, SUS430 and SUS304) are hardly softened by heat treatment at 200 ° C. That is, it was confirmed that when an Sn—Cu alloy active material layer was formed using a steel sheet as a core material, an electrode member having extremely high strength was obtained compared to the case where a copper foil was used as a core material.

《各電極部材を用いた負極特性試験》
上記のように作製した各電極部材から直径１５.９５８ｍｍ（面積２ｃｍ2）の円板状試料を打ち抜いた。この試料を作用極に用い、金属リチウム箔を参照極および対極に用い、セパレータとしてポリプロピレン製微多孔膜（厚さ２５μｍ）を用いて一般的な３電極式の試験セルを構成した。試験セルの筐体には宝泉株式会社製のＨＳ−３Ｅを使用し、電解液としてエチレンカーボネート（ＥＣ）とジエチレンカーボネート（ＤＥＣ）を１：１の体積比で混合した溶媒中にＬｉＰＦ6を１ｍｏｌ／Ｌの濃度で溶解させた液を使用した。試験セルは、ガス循環精製機付きグローブボックス内にセットし、グローブボックス内の環境は酸素濃度および水分濃度をいずれも１ｐｐｍ以下にコントロールした。 << Negative electrode characteristic test using each electrode member >>
A disk-shaped sample having a diameter of 15.958 mm (area 2 cm 2 ) was punched from each electrode member produced as described above. This sample was used as a working electrode, a metal lithium foil was used as a reference electrode and a counter electrode, and a general three-electrode test cell was constructed using a polypropylene microporous membrane (thickness 25 μm) as a separator. HS-3E manufactured by Hosen Co., Ltd. is used for the test cell casing, and LiPF 6 is mixed in a solvent in which ethylene carbonate (EC) and diethylene carbonate (DEC) are mixed at a volume ratio of 1: 1 as an electrolytic solution. A solution dissolved at a concentration of 1 mol / L was used. The test cell was set in a glove box equipped with a gas circulation purifier, and the environment in the glove box was controlled to have an oxygen concentration and a water concentration of 1 ppm or less.

各試験セルについて、活物質が有する理論容量（ｍＡｈ）を計算により求めた。次に、「理論容量（ｍＡｈ）／５（ｈ）」で表される電流値で完全充電したのち同じ電流値で完全放電させ、このときの放電容量を「電池容量Ｑ0（ｍＡｈ）」とした。引き続き０.５ＣｍＡの一定の充電率で完全充電したのち０.５ＣｍＡの一定の放電率で放電させるサイクルを２０回繰り返し、２０サイクル目の活物質単位体積当たりの放電電気容量Ｑ20（ｍＡｈ）を測定した。試験温度は２５℃である。ここで充電率は下記（１）式、放電率は下記（２）式で表される。
［充電率（ＣｍＡ）］＝［電池容量Ｑ0（ｍＡｈ）］／［充電時間（ｈ）］ …（１）
［放電率（ＣｍＡ）］＝［電池容量Ｑ0（ｍＡｈ）］／［放電時間（ｈ）］ …（２） About each test cell, the theoretical capacity | capacitance (mAh) which an active material has was calculated | required by calculation. Next, the battery is fully charged with the current value represented by “theoretical capacity (mAh) / 5 (h)” and then completely discharged with the same current value. The discharge capacity at this time is expressed as “battery capacity Q 0 (mAh)”. did. Subsequently, a full charge at a constant charge rate of 0.5 CmA and a discharge at a constant discharge rate of 0.5 CmA are repeated 20 times, and the discharge electric capacity Q 20 (mAh) per unit active material volume at the 20th cycle is calculated. It was measured. The test temperature is 25 ° C. Here, the charging rate is expressed by the following formula (1), and the discharging rate is expressed by the following formula (2).
[Charging rate (CmA)] = [Battery capacity Q 0 (mAh)] / [Charging time (h)] (1)
[Discharge rate (CmA)] = [Battery capacity Q 0 (mAh)] / [Discharge time (h)] (2)

各試料の負極特性は下記（３）式で定義される容量維持率によって評価した。
［容量維持率（％）］＝［評価対象試料のＱ20］／［評価対象試料の電池容量Ｑ0］×１００ …（３）
結果を表２に示す。 The negative electrode characteristics of each sample were evaluated by the capacity retention rate defined by the following formula (3).
[Capacity maintenance ratio (%)] = [Q 20 of sample to be evaluated] / [Battery capacity Q 0 of sample to be evaluated] × 100 (3)
The results are shown in Table 2.

Figure 2013131465
Figure 2013131465

本発明例のものは芯材の鋼シートが高強度を有するため充放電サイクル時にＳｎ−Ｃｕ活物質層の体積変化に起因する芯材の塑性変形が防止され、芯材とＳｎ−Ｃｕ合金活物質層の密着性が良好に維持されたことから銅箔を芯材に用いた従来例（Ｎｏ.１）と比べ、容量維持率が向上しており、電池性能の向上に有効であることがわかる。   In the example of the present invention, since the core steel sheet has high strength, plastic deformation of the core material due to the volume change of the Sn—Cu active material layer during the charge / discharge cycle is prevented, and the core material and the Sn—Cu alloy active material are prevented. Compared with the conventional example (No. 1) using a copper foil as a core material because the adhesion of the material layer is maintained well, the capacity retention rate is improved, which is effective in improving battery performance. Recognize.

これに対し、比較例Ｎｏ.８は銅被覆層を有しない中間製品を用いたので、それを熱処理して得られた電極部材の活物質層は充放電時の体積変化が大きい金属Ｓｎからなり、その体積変化によって充放電サイクル中に活物質層が崩壊して芯材鋼シートから剥離・脱落したことによって容量維持率は非常に小さい値となった。Ｎｏ.９はｔSn／ｔCuが過大であったため熱処理後に表層部に体積変化の大きい錫被覆層が比較的多く残存し、その体積膨張に起因して活物質層の密着性が低下して従来例（Ｎｏ.１）より容量維持率が低下した。Ｎｏ.１８はｔSn／ｔCuが過小であったためＳｎ−Ｃｕ合金活物質層中に占めるＣｕ6Ｓｎ5層の割合が本発明例よりも低下し、容量維持率の向上効果は見られなかった。Ｎｏ.２０はｔS／ｔが過小であったため銅箔に対する芯材の強度向上効果に乏しく、容量維持率の向上には至っていない。Ｎｏ.２２はｔSnが過大であったことにより表層部に金属Ｓｎ層が残存し、それが充放電サイクル中に崩壊して容量維持率が低下した。 On the other hand, since Comparative Example No. 8 used an intermediate product having no copper coating layer, the active material layer of the electrode member obtained by heat-treating it was made of metal Sn with a large volume change during charge / discharge. As a result of the volume change, the active material layer collapsed during the charge / discharge cycle and was peeled / dropped from the core steel sheet, resulting in a very small capacity retention rate. In No. 9, since t Sn / t Cu was excessive, a relatively large amount of tin coating layer having a large volume change remained in the surface layer portion after the heat treatment, and the adhesion of the active material layer was lowered due to the volume expansion. The capacity retention rate was lower than that of the conventional example (No. 1). In No. 18, since t Sn / t Cu was too small, the proportion of the Cu 6 Sn 5 layer in the Sn—Cu alloy active material layer was lower than that of the present invention example, and the effect of improving the capacity retention rate was not observed. It was. In No. 20, since t S / t was too small, the effect of improving the strength of the core with respect to the copper foil was poor, and the capacity retention rate was not improved. In No. 22, since t Sn was excessive, a metal Sn layer remained in the surface layer portion, which collapsed during the charge / discharge cycle, and the capacity retention rate decreased.

１ 鋼シート
２ 銅被覆層
３ 錫被覆層
４ 下地めっき層
５ Ｓｎ−Ｃｕ合金活物質層
１０ 中間製品の金属シート
２０ 電極部材 DESCRIPTION OF SYMBOLS 1 Steel sheet 2 Copper coating layer 3 Tin coating layer 4 Undercoat layer 5 Sn-Cu alloy active material layer 10 Metal sheet of intermediate product 20 Electrode member

Claims (2)

鋼シートの少なくとも片側表面に、銅被覆層を有し、その上に錫被覆層を有し、前記銅被覆層と前記錫被覆層は接しており、鋼シートの厚さをｔS、片面当たりの銅被覆層の厚さをｔCu、錫被覆層の厚さをｔSn、各被覆層を含めたシートのトータル厚さをｔとするとき、ｔS：３〜１００μｍ、ｔS／ｔ：０.２０以上、ｔSn：０.５〜１０.０μｍであり、かつ同一表面側においてｔSn／ｔCu：０.５〜２.５であるＳｎ−Ｃｕ合金活物質層担持電極部材用の中間製品金属シート。 At least one surface of the steel sheet has a copper coating layer, and has a tin coating layer thereon, the copper coating layer and the tin coating layer are in contact with each other, and the thickness of the steel sheet is t S When the thickness of the copper coating layer is t Cu , the thickness of the tin coating layer is t Sn , and the total thickness of the sheet including each coating layer is t, t S : 3 to 100 μm, t S / t: 0.2 or more, t Sn : 0.5 to 10.0 μm, and t Sn / t Cu : 0.5 to 2.5 on the same surface side. Intermediate product metal sheet. 前記Ｓｎ−Ｃｕ合金活物質は、リチウムイオン二次電池またはリチウムイオンキャパシタの負極活物質である請求項１に記載のＳｎ−Ｃｕ合金活物質層担持電極部材用の中間製品金属シート。   The intermediate product metal sheet for an Sn-Cu alloy active material layer-supported electrode member according to claim 1, wherein the Sn-Cu alloy active material is a negative electrode active material of a lithium ion secondary battery or a lithium ion capacitor.
JP2011281894A 2011-12-22 2011-12-22 INTERMEDIATE PRODUCT METAL SHEET FOR Sn-Cu ALLOY ACTIVE MATERIAL LAYER SUPPORTED ELECTRODE MEMBER Pending JP2013131465A (en)

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JPS60175375A (en) * 1984-02-20 1985-09-09 Hitachi Maxell Ltd Lithium organic secondary cell
JP2004319457A (en) * 2003-03-28 2004-11-11 Hitachi Maxell Ltd Anode for nonaqueous secondary battery, its manufacturing method, and nonaqueous secondary battery using above anode
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019114373A1 (en) * 2017-12-12 2019-06-20 中国科学院物理研究所 Composite-coated nano-tin negative electrode material, preparation method therefor and use thereof
US11362328B2 (en) 2017-12-12 2022-06-14 Institute Of Physics, Chinese Academy Of Sciences Composite-coated nano-tin negative electrode material and preparation method and use thereof

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