WO2011125557A1 - Copper foil for lithium-ion battery collector body - Google Patents

Copper foil for lithium-ion battery collector body Download PDF

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Publication number
WO2011125557A1
WO2011125557A1 PCT/JP2011/057440 JP2011057440W WO2011125557A1 WO 2011125557 A1 WO2011125557 A1 WO 2011125557A1 JP 2011057440 W JP2011057440 W JP 2011057440W WO 2011125557 A1 WO2011125557 A1 WO 2011125557A1
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Prior art keywords
copper foil
surface roughness
rolling
ion battery
avg
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PCT/JP2011/057440
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French (fr)
Japanese (ja)
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習太郎 西田
大輔 鮫島
嘉一郎 中室
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Jx日鉱日石金属株式会社
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Priority to KR1020127018875A priority Critical patent/KR101422376B1/en
Priority to CN201180016720.1A priority patent/CN102812585B/en
Publication of WO2011125557A1 publication Critical patent/WO2011125557A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • 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

Definitions

  • An important issue of the copper foil used as the negative electrode current collector is its adhesion to the negative electrode active material.
  • a copper foil for a current collector has been made focusing on improving the adhesion.
  • a surface treatment for forming irregularities on the surface of the copper foil which is called a roughening treatment
  • methods such as blasting, rolling with a rough surface roll, mechanical polishing, electrolytic polishing, chemical polishing and plating of electrodeposited grains are known, and among these, electrodeposited grain plating is particularly preferred. It is used a lot.
  • an object of the present invention is to provide a copper foil for a lithium ion battery current collector with high plate thickness accuracy. Moreover, this invention makes it another subject to provide the manufacturing method of such a copper foil.
  • the ratio of ⁇ RSm RSm max ⁇ RSm min to the average (RSm avg ) of the surface roughness RSm in the rolling parallel direction ( ⁇ RSm / RSm avg ) Is 0.5 or less.
  • the copper foil for a lithium ion battery current collector is for a lithium ion secondary battery negative electrode current collector.
  • the surface roughness Ra of the work roll used for the final pass is 0.03 ⁇ m or more in the final cold rolling step, and the surface of the work roll used for one pass immediately before the final pass.
  • Roughness Ra is less than 0.03 micrometer
  • the copper foil according to the present invention is excellent in plate thickness accuracy, it is possible to suppress an error in the coating amount of the negative electrode active material, so that it is possible to stabilize the battery capacity of a mass-produced lithium ion battery. .
  • the thickness of the copper foil is not particularly limited and may be appropriately selected depending on the required characteristics. Generally, the thickness is 1 to 100 ⁇ m, but when used as a current collector for a negative electrode of a lithium ion secondary battery, a battery having a higher capacity can be obtained by thinning the copper foil. From such a viewpoint, it is typically 2 to 50 ⁇ m, more typically about 5 to 20 ⁇ m.
  • Ra is a value obtained by folding the roughness curve from the center line and dividing the area obtained by the roughness curve and the center line by the reference length L, and is measured according to JIS B0601: 2001.
  • the average (Ra avg ) of the surface roughness Ra is an average of arbitrary 10 points.
  • ⁇ Ra is the maximum value Ra max and the minimum value among the measured 10 points Ra. is the difference of the Ra min is.
  • the arbitrary 10 points here do not mean 10 points in the vicinity of each measurement point.
  • the rolling direction depends on the obtained length.
  • 10 points are selected at intervals of at least 150 mm, preferably at intervals of 400 mm, more preferably at intervals of 1 m.
  • Ra at each measurement point is given by an average value obtained by measuring the vicinity of the measurement point three times. Each measurement point is Ra in the center in the width direction.
  • the measurement interval of 150 mm or more can be secured, the surface roughness of the sheet can be measured. .
  • the copper foil according to the present invention is characterized in that the average (Ra avg ) of the surface roughness Ra in the rolling parallel direction satisfies 0.01 to 0.15 ⁇ m.
  • the condition of 0.01 ⁇ m ⁇ Ra ⁇ 0.15 ⁇ m is that when Ra is less than 0.01 ⁇ m, the surface is smooth and sufficient adhesion to the negative electrode active material cannot be obtained, while when it exceeds 0.15 ⁇ m This is because, even if the roughness is reduced by rolling before the final pass and the variation in surface roughness is small, the rolling of the final pass varies.
  • Ra 0.03 ⁇ m or more is desirable, and 0.03 ⁇ m ⁇ Ra ⁇ 0.1 ⁇ m is a more preferable range from the viewpoint of stably producing appearance quality with few surface defects such as surface scratches.
  • ⁇ Ra Ra max ⁇ Ra min satisfies 0.025 ⁇ m or less.
  • ⁇ Ra exceeds 0.025 ⁇ m
  • ⁇ Ra before the final pass of the final rolling often exceeds 0.25 ⁇ m.
  • the surface roughness is large between the surface roughness and the surface roughness is small.
  • ⁇ Ra is preferably 0.025 ⁇ m or less, and more preferably 0.020 ⁇ m or less.
  • the oil pit is a depression generated when the rolling oil is pushed into the material to be rolled, and the density of the oil pit on the surface varies depending on the thickness of the oil film of the rolling oil. If the density of the oil pits on the surface is different, the thickness of the copper foil required by the gravimetric method is also affected, which causes variation. Therefore, it is desirable that the oil pits are uniformly distributed on the copper foil surface.
  • the amount of oil pits generated can be determined using the surface roughness RSm in the rolling parallel direction as an index.
  • RSm surface roughness
  • RSm max the number of oil pits on the surface
  • a smaller ⁇ RSm / RSm avg indicates that the oil pits are uniformly distributed on the copper foil surface.
  • the reason for dividing by RSm avg is that the variation in distribution is not necessarily large because ⁇ RSm is large. That is, even with the same ⁇ RSm, if RSm avg is large, the variation in distribution is not large and the influence is small. If RSm avg is small, the distribution is large and the influence is large.
  • RSm is an average value of the interval between the peaks and valleys obtained from the intersection where the roughness curve intersects the average line, and is measured in accordance with JIS B0601: 2001.
  • the average surface roughness RSm (RSm avg ) is an average of 10 arbitrary points
  • ⁇ RSm is the difference between RSm max which is the maximum value and RSm min which is the minimum value among 10 measured Ras. It is.
  • the arbitrary 10 points here do not mean 10 points in the vicinity of each measurement point.
  • the rolling direction depends on the obtained length. 10 points are selected at intervals of at least 150 mm, preferably at intervals of 400 mm, more preferably at intervals of 1 m.
  • RSm at each measurement point is given as an average value obtained by measuring the vicinity of the measurement point three times.
  • Each measurement point is RSm at the center in the width direction.
  • the proportion of the average value of the larger one of the values of the difference between (t avg), to the average value of the plate thickness (t avg) can be 1.3% or less. This ratio can be preferably 1.2% or less, more preferably 1.1% or less.
  • the surface roughness Ra can be controlled by adjusting the surface roughness of the work roll. For example, if a work roll having a large Ra is used, Ra of the rolled copper foil is increased, and conversely, a work having a small Ra is performed. If a roll is used, Ra of the rolled copper foil obtained will also become small.
  • the variation value itself increases as the average value increases. The same applies to the variation value of the surface roughness Ra. The larger the average value of the surface roughness Ra, the larger the variation value. Therefore, the average value of the surface roughness Ra is reduced in order to reduce the variation value of the surface roughness Ra. Should be reduced.
  • the oil pit distribution uniform In order to reduce the variation in the surface roughness RSm, it is important to make the oil pit distribution uniform. In order to make the oil pit distribution uniform, among other factors, it is important to keep the viscosity of the rolling oil constant during rolling.
  • the viscosity of the rolling oil is basically determined by the type of the rolling oil, but the viscosity is lowered by gradually increasing the rolling oil by the processing heat during rolling. As the viscosity of the rolling oil changes, if the degree to which the rolling oil is pushed into the copper foil surface changes, it leads to variations in the oil pit distribution. For example, when the rolling oil is kept at around 25 ° C.
  • the viscosity of the rolling oil used was 7.0 cSt (40 ° C.), and in the inventive examples, the temperature of the rolling oil during the final cold rolling was adjusted to be around 40 ° C.
  • Various characteristics were evaluated in the same manner as in Example 1. The test results are shown in Table 2.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Cell Electrode Carriers And Collectors (AREA)
  • Metal Rolling (AREA)

Abstract

Disclosed is a copper foil for a lithium-ion battery collector body, the plate thickness of which is highly precise. A copper foil for a lithium-ion battery collector body has an average surface roughness (Ra) in a rolling parallel direction (Raavg) of 0.01-0.15µm, and ΔRa=Ramax-Ramin is less than or equal to 0.025µm.

Description

リチウムイオン電池集電体用銅箔Copper foil for lithium-ion battery current collector
　本発明はリチウムイオン電池集電体用銅箔に関し、とりわけリチウムイオン二次電池負極集電体用銅箔に関する。 The present invention relates to a copper foil for a lithium ion battery current collector, and more particularly to a copper foil for a negative electrode current collector of a lithium ion secondary battery.
　リチウムイオン電池はエネルギー密度が高く、比較的高い電圧が得ることができるという特徴を有し、ノートパソコン、ビデオカメラ、デジタルカメラ、携帯電話等の小型電子機器用に多用されている。将来、電気自動車や一般家庭の分散配置型電源といった大型機器の電源としての利用も有望視されている。 Lithium ion batteries are characterized by high energy density and relatively high voltage, and are widely used for small electronic devices such as notebook computers, video cameras, digital cameras, and mobile phones. In the future, it is expected to be used as a power source for large equipment such as electric vehicles and distributed power sources for general households.
　リチウムイオン電池の電極体は一般に、正極、セパレータ及び負極が幾十にも巻回又は積層されたスタック構造を有している。一般的には、正極は、アルミニウム箔でできた正極集電体とその表面に設けられたＬｉＣｏＯ2、ＬｉＮｉＯ2及びＬｉＭｎ2Ｏ4といったリチウム複合酸化物を材料とする正極活物質から構成され、負極は銅箔でできた負極集電体とその表面に塗布されたカーボン等を材料とする負極活物質から構成される。 An electrode body of a lithium ion battery generally has a stack structure in which a positive electrode, a separator, and a negative electrode are wound or stacked in dozens. Generally, the positive electrode is composed of a positive electrode current collector made of an aluminum foil and a positive electrode active material made of a lithium composite oxide such as LiCoO 2 , LiNiO 2 and LiMn 2 O 4 provided on the surface thereof, The negative electrode is composed of a negative electrode current collector made of copper foil and a negative electrode active material made of carbon or the like coated on the surface thereof.
　負極集電体として使用される銅箔の重要課題として負極活物質との密着性があり、従来はこの密着性を向上させることを中心に集電体用銅箔の研究開発がなされてきた。活物質層との密着性を改善するための一般的な方法としては、予め粗化処理と呼ばれる銅箔表面に凹凸を形成する表面処理が挙げられる。粗化処理の方法としては、ブラスト処理、粗面ロールによる圧延、機械研磨、電解研磨、化学研磨及び電着粒のめっき等の方法が知られており、これらの中でも特に電着粒のめっきは多用されている。この技術は、硫酸銅酸性めっき浴を用いて、銅箔表面に樹枝状又は小球状に銅を多数電着せしめて微細な凹凸を形成し、投錨効果による密着性の改善を狙ったり、体積変化の大きな活物質の膨張時に活物質層の凹部に応力を集中させて亀裂を形成せしめ、集電体界面に応力が集中することによる剥離を防ぐことを狙ったりして行われている（例えば、特許第３７３３０６７号公報）。 An important issue of the copper foil used as the negative electrode current collector is its adhesion to the negative electrode active material. Conventionally, research and development of a copper foil for a current collector have been made focusing on improving the adhesion. As a general method for improving the adhesion with the active material layer, a surface treatment for forming irregularities on the surface of the copper foil, which is called a roughening treatment, can be mentioned. As a method of roughening treatment, methods such as blasting, rolling with a rough surface roll, mechanical polishing, electrolytic polishing, chemical polishing and plating of electrodeposited grains are known, and among these, electrodeposited grain plating is particularly preferred. It is used a lot. This technology uses a copper sulfate acidic plating bath to deposit a large number of copper in a dendritic or small spherical shape on the surface of the copper foil to form fine irregularities, aiming to improve the adhesion by the anchoring effect, or to change the volume It is carried out with the aim of preventing cracking by concentrating stress on the concave portion of the active material layer during expansion of a large active material, and preventing peeling due to stress concentration on the current collector interface (for example, Japanese Patent No. 3733067).
　特許第３７３３０６５号公報には、好ましい表面性状が粗さのパラメータで具体的に特定されており、表面粗さＲａの値が大きな銅箔を集電体として用いることにより、集電体と活物質との密着性が向上することが記載されている（段落０２０９）。集電体の表面粗さＲａは、０．０１μｍ以上であることが好ましく、さらに好ましくは０．０１～１μｍであり、さらに好ましくは０．０５～０．５μｍであるとされる（段落００２１等）。集電体の表面粗さＲａと局部山頂の平均間隔Ｓは、１００Ｒａ≧Ｓの関係を有することが好ましいとされる（段落００２２等）。集電体表面の凹凸の凸部の形状は錐体状であることが好ましいとされる（段落００２３等）。
　そして、このような表面形態は、電解銅箔（段落００４４）、圧延銅箔の表面に電解法により銅を析出させて表面を粗面化すること（段落００４５）、及びエメリー紙で研磨処理すること（段落０２０５）で得られることが記載されている。 In Japanese Patent No. 3733065, a preferable surface property is specifically specified by a roughness parameter, and a current collector and an active material are obtained by using a copper foil having a large surface roughness Ra as a current collector. It is described that the adhesiveness to the surface is improved (paragraph 0209). The surface roughness Ra of the current collector is preferably 0.01 μm or more, more preferably 0.01 to 1 μm, and further preferably 0.05 to 0.5 μm (paragraph 0021 and the like). ). The surface roughness Ra of the current collector and the average interval S between the local peaks are preferably 100Ra ≧ S (paragraph 0022 and the like). The shape of the convex and concave portions on the surface of the current collector is preferably a cone (paragraph 0023 and the like).
Such surface morphology is obtained by electrolytic copper foil (paragraph 0044), precipitation of copper on the surface of the rolled copper foil by an electrolytic method to roughen the surface (paragraph 0045), and polishing with emery paper. (Paragraph 0205).
特許第３７３３０６７号公報Japanese Patent No. 3733067 特許第３７３３０６５号公報Japanese Patent No. 3733065
　リチウムイオン電池の電池容量は負極活物質の塗布量に応じて変化するため、電池特性の安定化を図るためには負極活物質の塗布量の制御・管理が重要となるが、負極活物質の塗布工程における塗布量の管理は、塗布後の銅箔を含めた重量で行われているのが現状である。したがって、集電体である銅箔の厚みが一定でなければ塗布すべき負極活物質の量を適切に管理することができない。銅箔の比重は約８．９２ｇ／ｃｍ3であり、負極活物質として使用されるカーボンの比重は約０．５ｇ／ｃｍ3であることから、例えば、銅箔の厚み０．１μｍに相当するカーボンの厚みは１．７８μｍである。したがって、厚み１０μｍを目標として銅箔を製造したときに厚みがわずか０．１μｍ（１．００％）ばらつくだけで、カーボンの厚みに１．７８μｍ（厚み４０μｍを目標とした場合は４．４５％に相当する。）もの誤差を生じさせてしまうことになる。これは、４０μｍの厚みの活物質では、４．４５％のばらつきに相当する。すなわち、銅箔の僅かな厚みのばらつきが活物質の厚みに大きく影響を与える結果となる。そのため、板厚精度に優れた銅箔が望まれる。 Since the battery capacity of a lithium ion battery changes according to the amount of the negative electrode active material applied, it is important to control and manage the amount of the negative electrode active material applied in order to stabilize the battery characteristics. At present, the amount of coating in the coating process is managed by the weight including the copper foil after coating. Therefore, unless the thickness of the copper foil as the current collector is constant, the amount of the negative electrode active material to be applied cannot be properly managed. Since the specific gravity of the copper foil is about 8.92 g / cm 3 and the specific gravity of the carbon used as the negative electrode active material is about 0.5 g / cm 3 , for example, this corresponds to a thickness of the copper foil of 0.1 μm. The thickness of the carbon is 1.78 μm. Therefore, when the copper foil is manufactured with a target thickness of 10 μm, the thickness varies by only 0.1 μm (1.00%), and the carbon thickness is 1.78 μm (4.45% when the target thickness is 40 μm). Will cause an error. This corresponds to a variation of 4.45% for an active material having a thickness of 40 μm. That is, a slight thickness variation of the copper foil greatly affects the thickness of the active material. Therefore, a copper foil excellent in plate thickness accuracy is desired.
　しかしながら、集電体用銅箔のこれまでの開発の方向性は、負極活物質との密着性向上を狙ったミクロ的な視点での表面性状制御が圧倒的であった。そのため、マクロ的な視点で銅箔の板厚精度を向上させて、リチウムイオン電池の容量安定性を図るという課題は未解決のままである。 However, the direction of development of copper foils for current collectors so far has been overwhelming in controlling surface properties from a microscopic viewpoint aimed at improving adhesion to the negative electrode active material. Therefore, the problem of improving the plate thickness accuracy of the copper foil from a macro viewpoint and achieving the capacity stability of the lithium ion battery remains unsolved.
　そこで、本発明は板厚精度の高いリチウムイオン電池集電体用銅箔を提供することを課題の一つとする。また、本発明はそのような銅箔の製造方法を提供することを別の課題の一つとする。 Therefore, an object of the present invention is to provide a copper foil for a lithium ion battery current collector with high plate thickness accuracy. Moreover, this invention makes it another subject to provide the manufacturing method of such a copper foil.
　銅箔は圧延銅箔と電解銅箔に大別される。圧延銅箔においては、板厚精度は圧延機の機能（能力）に起因することが多いが、現状の圧延機では板厚精度は目標とする板厚１０μｍにおいて±１．６％が限度である。根本的な対策として圧延機の改造や開発も望まれるが、多額の研究開発費用が必要となるため、直ちに行うことは困難である。 Copper foil is roughly divided into rolled copper foil and electrolytic copper foil. In the rolled copper foil, the plate thickness accuracy often depends on the function (capability) of the rolling mill, but in the current rolling mill, the plate thickness accuracy is limited to ± 1.6% at a target plate thickness of 10 μm. . As a fundamental measure, remodeling and development of rolling mills is also desired, but it requires a large amount of research and development and is difficult to do immediately.
　本発明者はこのような実情の下で、上記課題を解決するために研究を重ねたところ、圧延銅箔の製造過程において、圧延の多くはフィードフォワードでの板厚制御のため、製品の板厚精度について、最終冷間圧延の最終パス前の表面粗さのばらつきが板厚制御に影響を与える要因の一つであることに着目し、最終パスの前段階において表面粗さを小さくし、表面粗さのばらつきを小さくすることで、板厚精度が向上することを見出した。具体的には、最終パス前の圧延について表面粗さの小さなワークロールを用い、最終パスにおいて所望する表面粗さのワークロールを用いることで最終的に板厚精度がよく、所望の表面粗さを有する銅箔を得ることができることが分かった。集電体用銅箔では活物質との密着性を考慮する関係から一定の表面粗さが要求されるが、最終冷間圧延の最終パス前において表面粗さを可及的に小さくしておくことで、板厚精度を高めながら所望の表面粗さを有することができるのである。 Under such circumstances, the present inventor has conducted research to solve the above-described problems. In the manufacturing process of rolled copper foil, many of the rolling operations are performed in order to control the thickness of the product in the feed forward. With regard to thickness accuracy, paying attention to the fact that the variation in surface roughness before the final pass of the final cold rolling is one of the factors affecting the sheet thickness control, reduce the surface roughness before the final pass, It has been found that the plate thickness accuracy is improved by reducing the variation of the surface roughness. Specifically, using a work roll having a small surface roughness for rolling before the final pass, and using a work roll having a desired surface roughness in the final pass, the plate thickness accuracy is finally good and the desired surface roughness is obtained. It has been found that a copper foil with can be obtained. The current collector copper foil requires a certain surface roughness in consideration of the adhesion to the active material, but the surface roughness should be as small as possible before the final pass of the final cold rolling. Thus, the desired surface roughness can be obtained while increasing the plate thickness accuracy.
　以上の知見を基礎として完成した本発明は一側面において、圧延平行方向における表面粗さＲａの平均（Ｒａavg）が０．０１～０．１５μｍであり、ΔＲａ＝Ｒａmax－Ｒａminが０．０２５μｍ以下であることを特徴とするリチウムイオン電池集電体用銅箔である。 In one aspect of the present invention completed based on the above findings, the average (Ra avg ) of surface roughness Ra in the rolling parallel direction is 0.01 to 0.15 μm, and ΔRa = Ra max −Ra min is 0.00. A copper foil for a lithium ion battery current collector, characterized by having a thickness of 025 μm or less.
　本発明に係るリチウムイオン電池集電体用銅箔の一実施形態においては、銅箔の板厚が５～２０μｍである。 In one embodiment of the copper foil for a lithium ion battery current collector according to the present invention, the thickness of the copper foil is 5 to 20 μm.
　本発明に係るリチウムイオン電池集電体用銅箔の別の一実施形態においては、銅箔の板厚の最大値（ｔmax）と板厚の平均値（ｔavg）との差、又は最小値（ｔmin）と板厚の平均値（ｔavg）との差のいずれか大きい方の値の、板圧の平均値（ｔavg）に対する割合が１．３％以下である。 In another embodiment of the copper foil for a lithium ion battery current collector according to the present invention, the difference between the maximum value (t max ) of the copper foil thickness and the average value (t avg ) of the copper foil, or the minimum any larger value of the difference value between (t min) the thickness of the average value (t avg), the ratio to the average value of the plate thickness (t avg) is less than 1.3%.
　本発明に係るリチウムイオン電池集電体用銅箔の一実施形態においては、圧延平行方向における表面粗さＲＳｍの平均（ＲＳｍavg）に対するΔＲＳｍ＝ＲＳｍmax－ＲＳｍminの比（ΔＲＳｍ／ＲＳｍavg）が０．５以下である。 In one embodiment of the copper foil for a lithium ion battery current collector according to the present invention, the ratio of ΔRSm = RSm max −RSm min to the average (RSm avg ) of the surface roughness RSm in the rolling parallel direction (ΔRSm / RSm avg ) Is 0.5 or less.
　本発明に係るリチウムイオン電池集電体用銅箔の別の一実施形態においては、銅箔がリチウムイオン二次電池負極集電体用である。 In another embodiment of the copper foil for a lithium ion battery current collector according to the present invention, the copper foil is for a lithium ion secondary battery negative electrode current collector.
　本発明は別の一側面において、本発明に係る銅箔を集電体として備えたリチウムイオン電池である。 In another aspect, the present invention is a lithium ion battery including the copper foil according to the present invention as a current collector.
　本発明は更に別の一側面において、最終冷間圧延工程において、最終パスに用いられるワークロールの表面粗さＲａが０．０３μｍ以上であり、最終パス直前の１パスに用いられるワークロールの表面粗さＲａが０．０３μｍ未満であることを特徴とするリチウムイオン電池集電体用銅箔の製造方法である。 In still another aspect of the present invention, the surface roughness Ra of the work roll used for the final pass is 0.03 μm or more in the final cold rolling step, and the surface of the work roll used for one pass immediately before the final pass. Roughness Ra is less than 0.03 micrometer, It is a manufacturing method of the copper foil for lithium ion battery collectors characterized by the above-mentioned.
　本発明に係る銅箔は板厚精度に優れているため、負極活物質の塗布量の誤差を抑えることが可能となるので、量産されるリチウムイオン電池の電池容量の安定化を図ることができる。 Since the copper foil according to the present invention is excellent in plate thickness accuracy, it is possible to suppress an error in the coating amount of the negative electrode active material, so that it is possible to stabilize the battery capacity of a mass-produced lithium ion battery. .
　本発明において使用する銅箔基材は圧延銅箔である。「銅箔」には銅合金箔も含まれるものとする。銅箔の材料としては、特に制限はなく、用途や要求特性に応じて適宜選択すればよい。例えば、限定的ではないが、高純度の銅（無酸素銅やタフピッチ銅等）の他、Ｓｎ、Ａｇ、Ｆｅ、Ｉｎ、Ｔｅ等を添加した銅合金、Ｎｉ、Ｓｉ等を添加したＣｕ－Ｎｉ－Ｓｉ系銅合金、Ｃｒ、Ｚｒ等を添加したＣｕ－Ｚｒ系、Ｃｕ－Ｃｒ－Ｚｒ系銅合金のような銅合金が挙げられる。圧延銅箔は、強度が高く、振動が継続的に発生する環境に対応でき、耐屈曲性が高い点で優れている。 The copper foil base material used in the present invention is a rolled copper foil. “Copper foil” includes copper alloy foil. There is no restriction | limiting in particular as a material of copper foil, What is necessary is just to select suitably according to a use or a required characteristic. For example, but not limited to, high purity copper (oxygen-free copper, tough pitch copper, etc.), copper alloy added with Sn, Ag, Fe, In, Te, etc., Cu—Ni added with Ni, Si, etc. Examples thereof include copper alloys such as -Si based copper alloys, Cu-Zr based alloys to which Cr, Zr and the like are added, and Cu-Cr-Zr based copper alloys. The rolled copper foil is excellent in that it has high strength, can cope with an environment in which vibration continuously occurs, and has high bending resistance.
　銅箔の厚みは特に制限はなく、要求特性に応じて適宜選択すればよい。一般的には１～１００μｍであるが、リチウムイオン二次電池負極の集電体として使用する場合、銅箔を薄肉化した方がより高容量の電池を得ることができる。そのような観点から、典型的には２～５０μｍ、より典型的には５～２０μｍ程度である。 The thickness of the copper foil is not particularly limited and may be appropriately selected depending on the required characteristics. Generally, the thickness is 1 to 100 μm, but when used as a current collector for a negative electrode of a lithium ion secondary battery, a battery having a higher capacity can be obtained by thinning the copper foil. From such a viewpoint, it is typically 2 to 50 μm, more typically about 5 to 20 μm.
　本発明に係る銅箔は、圧延平行方向における表面粗さＲａの平均（Ｒａavg）、及びΔＲａ＝Ｒａmax－Ｒａminによって規定される。Ｒａは粗さ曲線を中心線から折り返し、その粗さ曲線と中心線によって得られた面積を基準長さＬで割った値であり、ＪＩＳ　Ｂ０６０１：２００１に準拠して測定される。本発明において表面粗さＲａの平均（Ｒａavg）とは、任意の１０点の平均であり、本発明においてΔＲａとは、測定した１０点のＲａのうち、最大値であるＲａmaxと最小値であるＲａminの差である。ただし、ここでいう任意の１０点は、各測定点がお互いの近傍での１０点を意味するものではなく、たとえば、コイル状の場合であれば、得られた長さに応じて、圧延方向に少なくとも１５０ｍｍ間隔、好ましくは４００ｍｍ間隔、より好ましくは１ｍ間隔以上で１０点を選択する。各測定点におけるＲａは測定点近傍を３回測定した平均値で与えられる。なお、各測定点は、幅方向中央のＲａとする。また、電池を分解した場合には複数重ねられた負極用銅箔のシートであっても１５０ｍｍ以上の測定間隔が確保できるのであれば、そのシートに対して表面粗さの測定をすることができる。 The copper foil according to the present invention is defined by the average (Ra avg ) of surface roughness Ra in the rolling parallel direction and ΔRa = Ra max −Ra min . Ra is a value obtained by folding the roughness curve from the center line and dividing the area obtained by the roughness curve and the center line by the reference length L, and is measured according to JIS B0601: 2001. In the present invention, the average (Ra avg ) of the surface roughness Ra is an average of arbitrary 10 points. In the present invention, ΔRa is the maximum value Ra max and the minimum value among the measured 10 points Ra. is the difference of the Ra min is. However, the arbitrary 10 points here do not mean 10 points in the vicinity of each measurement point. For example, in the case of a coil shape, the rolling direction depends on the obtained length. 10 points are selected at intervals of at least 150 mm, preferably at intervals of 400 mm, more preferably at intervals of 1 m. Ra at each measurement point is given by an average value obtained by measuring the vicinity of the measurement point three times. Each measurement point is Ra in the center in the width direction. In addition, when the battery is disassembled, even if a plurality of sheets of negative electrode copper foil are stacked, if the measurement interval of 150 mm or more can be secured, the surface roughness of the sheet can be measured. .
　本発明に係る銅箔は圧延平行方向における表面粗さＲａの平均（Ｒａavg）について、０．０１～０．１５μｍを満たすことを特徴としている。０．０１μｍ≦Ｒａ≦０．１５μｍを条件としたのは、Ｒａが０．０１μｍ未満だと表面が平滑で負極活物質との十分な接着性が得られない一方で、０．１５μｍを超えるとたとえ、最終パス前の圧延で粗さを小さくして表面粗さのばらつきが少ない状態にしても最終パスの圧延でばらついてしまうからである。しかし、表面傷等の表面欠陥の少ない外観品質が安定的に作りこめるという観点から考えるとＲａ０．０３μｍ以上が望ましく、０．０３μｍ≦Ｒａ≦０．１μｍがより好ましい範囲である。 The copper foil according to the present invention is characterized in that the average (Ra avg ) of the surface roughness Ra in the rolling parallel direction satisfies 0.01 to 0.15 μm. The condition of 0.01 μm ≦ Ra ≦ 0.15 μm is that when Ra is less than 0.01 μm, the surface is smooth and sufficient adhesion to the negative electrode active material cannot be obtained, while when it exceeds 0.15 μm This is because, even if the roughness is reduced by rolling before the final pass and the variation in surface roughness is small, the rolling of the final pass varies. However, Ra 0.03 μm or more is desirable, and 0.03 μm ≦ Ra ≦ 0.1 μm is a more preferable range from the viewpoint of stably producing appearance quality with few surface defects such as surface scratches.
　また、ΔＲａ＝Ｒａmax－Ｒａminが０．０２５μｍ以下を満たすことも特徴としている。ΔＲａ＝Ｒａmax－Ｒａminが０．０２５μｍ以下を条件としたのは、製品である最終圧延後の銅箔のΔＲａが０．０２５μｍ以下であれば、最終圧延の最終パス前のΔＲａが０．０２５μｍ以下であることを意味することができるからである。最終圧延の最終パス前のΔＲａが０．０２５μｍ以下であれば、最終圧延の最終パス時での表面粗さのばらつき（変動）による板厚制御への影響は小さく、最終パスでのすなわち、製品の板厚精度が向上する。ΔＲａが０．０２５μｍを超える場合には、最終圧延の最終パス前のΔＲａが０．２５μｍを超えている場合が多く、その場合には表面粗さの大きいところと表面粗さの小さいところの粗さが最終圧延の最終パスの板厚制御に与える影響が異なり、結果としてその条における最終圧延板厚のばらつきが大きくなる。ΔＲａは好ましくは０．０２５μｍ以下であり、より好ましくは０．０２０μｍ以下である。 Further, ΔRa = Ra max −Ra min satisfies 0.025 μm or less. The condition that ΔRa = Ra max −Ra min is 0.025 μm or less is that if ΔRa of the copper foil after the final rolling as a product is 0.025 μm or less, ΔRa before the final pass of the final rolling is 0.00. This is because it can mean 025 μm or less. If ΔRa before the final pass of the final rolling is 0.025 μm or less, the influence on the sheet thickness control due to the variation (variation) of the surface roughness at the final pass of the final rolling is small, that is, the product in the final pass. The plate thickness accuracy is improved. When ΔRa exceeds 0.025 μm, ΔRa before the final pass of the final rolling often exceeds 0.25 μm. In this case, the surface roughness is large between the surface roughness and the surface roughness is small. Have different effects on the thickness control of the final pass of the final rolling, and as a result, the variation of the final rolled thickness in the strip becomes large. ΔRa is preferably 0.025 μm or less, and more preferably 0.020 μm or less.
　一方で、圧延銅箔においては、ロール目によって定まる表面粗さとは別に、オイルピットとよばれる圧延銅箔特有のくぼみが表面上に多数存在する。オイルピットは圧延油が被圧延材に押し込まれて発生するくぼみであり、圧延油の油膜の厚さによって表面上のオイルピットの密度が異なることとなる。表面上のオイルピットの密度が異なれば、重量法で求められる銅箔の板厚にも影響を与え、ばらつきの要因となる。従って、オイルピットは銅箔表面上に均一に分布しているほうが望ましい。 On the other hand, in the rolled copper foil, apart from the surface roughness determined by the rolls, there are a number of depressions unique to the rolled copper foil called oil pits on the surface. The oil pit is a depression generated when the rolling oil is pushed into the material to be rolled, and the density of the oil pit on the surface varies depending on the thickness of the oil film of the rolling oil. If the density of the oil pits on the surface is different, the thickness of the copper foil required by the gravimetric method is also affected, which causes variation. Therefore, it is desirable that the oil pits are uniformly distributed on the copper foil surface.
　オイルピットの発生量は、圧延平行方向における表面粗さＲＳｍを指標とすることができる。ＲＳｍが大きい場合には表面上のオイルピットが少なく、ＲＳｍが小さい場合にはオイルピットの量が多いことを示す。板厚精度の特定に影響を与えるのは、オイルピットの分布のばらつきであることから、圧延平行方向における表面粗さＲＳｍの平均（ＲＳｍavg）に対するΔＲＳｍ＝ＲＳｍmax－ＲＳｍminの比（ΔＲＳｍ／ＲＳｍavg）を指標とした。ΔＲＳｍ／ＲＳｍavgが小さいほど、オイルピットが銅箔表面上に均一に分布していることを示す。ＲＳｍavgで割ることとしたのは、分布のばらつきにおいては、ΔＲＳｍが大きいからといって必ずしもばらつきは大きいとはいえないからである。すなわち、たとえ、同じΔＲＳｍでも、ＲＳｍavgが大きければ分布のばらつきとしては大きくないためその影響は小さく、ＲＳｍavgが小さい場合には分布のばらつきとして大きいため影響が大きくなる。 The amount of oil pits generated can be determined using the surface roughness RSm in the rolling parallel direction as an index. When RSm is large, the number of oil pits on the surface is small, and when RSm is small, the amount of oil pits is large. Since it is the dispersion of oil pit distribution that affects the specification of the plate thickness accuracy, the ratio of ΔRSm = RSm max −RSm min to the average (RSm avg ) of the surface roughness RSm in the rolling parallel direction (ΔRSm / RSm avg) was used as the index. A smaller ΔRSm / RSm avg indicates that the oil pits are uniformly distributed on the copper foil surface. The reason for dividing by RSm avg is that the variation in distribution is not necessarily large because ΔRSm is large. That is, even with the same ΔRSm, if RSm avg is large, the variation in distribution is not large and the influence is small. If RSm avg is small, the distribution is large and the influence is large.
　圧延速度を速く、圧延油の粘度を高く、又は１パス当たりの圧下率を小さくすることでオイルピットの発生量が増加し、ＲＳｍが小さくなりやすい。逆に、圧延速度を遅く、圧延油の粘度を低く、又は１パス当たりの圧下率を大きくすることでオイルピットの発生量が減少し、ＲＳｍが大きくなりやすい。 When the rolling speed is increased, the viscosity of the rolling oil is increased, or the reduction rate per pass is decreased, the amount of oil pits generated increases, and RSm tends to decrease. Conversely, by reducing the rolling speed, lowering the viscosity of the rolling oil, or increasing the rolling reduction per pass, the amount of oil pits decreases and RSm tends to increase.
　ＲＳｍは粗さ曲線が平均線と交差する交点から求めた山谷－周期の間隔の平均値であり、ＪＩＳ　Ｂ０６０１：２００１に準拠して測定される。本発明において表面粗さＲＳｍの平均（ＲＳｍavg）は任意の１０点の平均であり、ΔＲＳｍとは測定した１０点のＲａのうち、最大値であるＲＳｍmaxと最小値であるＲＳｍminの差である。ただし、ここでいう任意の１０点は、各測定点がお互いの近傍での１０点を意味するものではなく、たとえば、コイル状の場合であれば、得られた長さに応じて、圧延方向に少なくとも１５０ｍｍ間隔、好ましくは４００ｍｍ間隔、より好ましくは１ｍ間隔以上で１０点を選択する。各測定点におけるＲＳｍは測定点近傍を３回測定した平均値で与えられる。なお、各測定点は、幅方向中央のＲＳｍとする。また、電池を分解した場合には複数重ねられた負極用銅箔のシートであっても１５０ｍｍ以上の測定間隔が確保できるのであれば、そのシートに対して表面粗さの測定をすることができる。 RSm is an average value of the interval between the peaks and valleys obtained from the intersection where the roughness curve intersects the average line, and is measured in accordance with JIS B0601: 2001. In the present invention, the average surface roughness RSm (RSm avg ) is an average of 10 arbitrary points, and ΔRSm is the difference between RSm max which is the maximum value and RSm min which is the minimum value among 10 measured Ras. It is. However, the arbitrary 10 points here do not mean 10 points in the vicinity of each measurement point. For example, in the case of a coil shape, the rolling direction depends on the obtained length. 10 points are selected at intervals of at least 150 mm, preferably at intervals of 400 mm, more preferably at intervals of 1 m. RSm at each measurement point is given as an average value obtained by measuring the vicinity of the measurement point three times. Each measurement point is RSm at the center in the width direction. In addition, when the battery is disassembled, even if a plurality of sheets of negative electrode copper foil are stacked, if the measurement interval of 150 mm or more can be secured, the surface roughness of the sheet can be measured. .
　本発明に係る銅箔の好ましい一実施形態においては、ΔＲＳｍ／ＲＳｍavgが０．５以下である。 In a preferred embodiment of a copper foil according to the present invention, ΔRSm / RSm avg is 0.5 or less.
　本発明に係る銅箔の好ましい一実施形態においては、銅箔の板厚の最大値（ｔmax）と板厚の平均値（ｔavg）との差、又は最小値（ｔmin）と板厚の平均値（ｔavg）との差のいずれか大きい方の値の、板圧の平均値（ｔavg）に対する割合が１．３％以下とすることができる。この割合は好ましくは１．２％以下とすることもでき、より好ましくは１．１％以下とすることもできる。 In a preferred embodiment of the copper foil according to the present invention, the difference between the maximum value (t max ) of the copper foil thickness and the average value (t avg ) of the plate thickness, or the minimum value (t min ) and the plate thickness. the proportion of the average value of the larger one of the values of the difference between (t avg), to the average value of the plate thickness (t avg) can be 1.3% or less. This ratio can be preferably 1.2% or less, more preferably 1.1% or less.
　次に、本発明に係る銅箔の製造方法について説明する。表面粗さＲａの制御はワークロールの表面粗さの調整により行うことができ、例えば、Ｒａの大きなワークロールを使用すれば得られる圧延銅箔のＲａも大きくなり、逆に、Ｒａの小さなワークロールを使用すれば得られる圧延銅箔のＲａも小さくなる。一方、一般的にばらつきの値自体は平均値が大きい方が大きくなる。表面粗さＲａのばらつきの値についても同様で、表面粗さＲａの平均値が大きいほうがばらつきの値も大きいので、表面粗さＲａのばらつきの値を低減するため、表面粗さＲａの平均値を小さくすればよい。 Next, a method for producing a copper foil according to the present invention will be described. The surface roughness Ra can be controlled by adjusting the surface roughness of the work roll. For example, if a work roll having a large Ra is used, Ra of the rolled copper foil is increased, and conversely, a work having a small Ra is performed. If a roll is used, Ra of the rolled copper foil obtained will also become small. On the other hand, in general, the variation value itself increases as the average value increases. The same applies to the variation value of the surface roughness Ra. The larger the average value of the surface roughness Ra, the larger the variation value. Therefore, the average value of the surface roughness Ra is reduced in order to reduce the variation value of the surface roughness Ra. Should be reduced.
　ただし、各々の製品においては、負極活物質との密着性などの観点から求められる表面粗さの要求があるので、最終的には求められる値に作りこむ必要がある。また、冷間圧延においては、圧延速度を高く設定できるという圧延効率の観点では表面粗さがある程度粗いほうがよい。
　そこで、例えば、最終冷間圧延の最終パス直前の１パスについてのみ表面粗さの小さいワークロールを用いて表面粗さの小さな、すなわち表面が平滑な銅箔を作り込み、最終パスで表面粗さの大きなワークロールを用いて所望の表面粗さＲａを作り込む。
　これにより、高い厚み精度を得ながら所望の表面粗さを有し、活物質との密着性の良好な銅箔を得ることができる。すなわち、最終パスの２パス前までは表面粗さＲａの粗いロールでよく、最終パス直前の１パスのみ、前パス及び最終パスより小さい粗さのロールを用いる。 However, in each product, since there is a demand for surface roughness required from the viewpoint of adhesion to the negative electrode active material, it is necessary to finally make it to the required value. In cold rolling, the surface roughness should be rough to some extent from the viewpoint of rolling efficiency that the rolling speed can be set high.
Therefore, for example, a copper foil having a small surface roughness, that is, a smooth surface is formed by using a work roll having a small surface roughness for only one pass immediately before the final pass of the final cold rolling, and the surface roughness is obtained in the final pass. The desired surface roughness Ra is made using a large work roll.
Thereby, it is possible to obtain a copper foil having a desired surface roughness and good adhesion to the active material while obtaining high thickness accuracy. That is, a roll having a surface roughness Ra may be used up to two passes before the final pass, and a roll having a smaller roughness than the previous pass and the final pass is used for only one pass immediately before the final pass.
　最終パス直前の１パスのみならず、それ以前のパスについても表面粗さの小さなワークロールを使用してもよいが、表面粗さの小さいロールは、圧延速度を上げることが出来ないため、生産性の観点からは望まれない。そこで通常は最終パス直前のパスに使用するワークロールのみ表面粗さを小さくする。ただし、生産性の観点を無視すれば、最終パス直前の１パスよりも前のパスについても表面粗さの小さいロールとする方が表面粗さのばらつきの低減効果は高い。例えば最終パス直前の２パスだけ表面粗さの小さいロールとするのでも効果はある。 Work rolls with a small surface roughness may be used not only for the first pass just before the final pass, but also for the passes before that. However, a roll with a small surface roughness cannot be rolled up, so it can be produced. Not desirable from a gender perspective. Therefore, the surface roughness is usually reduced only for the work roll used in the pass immediately before the final pass. However, if the viewpoint of productivity is ignored, the effect of reducing the variation in surface roughness is higher when a roll having a smaller surface roughness is used in the pass before the first pass immediately before the final pass. For example, it is effective to use a roll having a small surface roughness for only two passes immediately before the final pass.
　最終パスにおいて、銅箔の圧延平行方向におけるＲａの平均（Ｒａavg）が０．０１～０．１５μｍとなるように、ワークロールは表面粗さＲａが０．０１μｍを超えるものを用いることになるため、表面粗さのばらつきの値を小さくするためには、最終パス直前の１パスに用いられるワークロールの表面粗さＲａは、最終パスに用いられるワークロールより小さくなければならない。したがって、最終パス直前の１パスに用いられるワークロールの表面粗さＲａは、０．０１μｍ以下が望ましい。
　しかしながら、表面粗さＲａが０．０１μｍ以下で表面傷等の外観上の問題ないロールを安定的に作製することは、高い技術を要し、コスト的にも割高となる。
　したがって、より好ましい範囲は、最終パスにおいて使用するワークロールは表面粗さＲａが０．０３μｍ以上であるのが好ましく、ゆえに最終パス直前の１パスに用いられるワークロールの表面粗さＲａは、０．０３μｍ未満とすることが望ましい。 In the final pass, a work roll having a surface roughness Ra exceeding 0.01 μm is used so that an average (Ra avg ) of Ra in the rolling parallel direction of the copper foil is 0.01 to 0.15 μm. Therefore, in order to reduce the variation value of the surface roughness, the surface roughness Ra of the work roll used for one pass immediately before the final pass must be smaller than the work roll used for the final pass. Therefore, the surface roughness Ra of the work roll used in one pass immediately before the final pass is desirably 0.01 μm or less.
However, stably producing a roll having a surface roughness Ra of 0.01 μm or less and having no appearance problems such as surface scratches requires high technology and is expensive.
Accordingly, a more preferable range is that the work roll used in the final pass preferably has a surface roughness Ra of 0.03 μm or more. Therefore, the surface roughness Ra of the work roll used in one pass immediately before the final pass is 0. It is desirable to be less than 0.03 μm.
　表面粗さＲＳｍのばらつきを低減するためには、オイルピットの分布を均一にすることが重要となる。オイルピットの分布を均一にするには、いくつかの要因の中でも圧延油の粘度を圧延中に一定に保つことが重要である。圧延油の粘度は圧延油の種類によって基本的に定まるが、圧延中の加工熱によって圧延油が徐々に上昇することで粘度が低下する。圧延油の粘度の変化に伴い、圧延油が銅箔表面へ押し込まれる度合いが変化すると、オイルピット分布のばらつきにつながる。
　例えば、圧延油は、圧延前の温度調整においては２５℃前後に保たれる時、圧延油を圧延中のワークロールに噴射すると加工熱によって上昇したワークロール等からの熱が伝わり、圧延油は４０℃くらいまで上昇する。この状態で維持できれば、オイルピットの分布のばらつきは少なく、銅箔形状には問題ない。しかしながら、圧延油の温度制御が十分でなく、圧延油温度が４０℃を超えてばらつく場合には、銅箔の表面性状がばらつきやすくなるだけでなく、板形状にも影響を与える。従って、圧延中の圧延油の温度を４０℃程度に調整するためには、ロール噴射前の圧延油温度、圧延速度、加工度等を総合的に調整する必要がある。 In order to reduce the variation in the surface roughness RSm, it is important to make the oil pit distribution uniform. In order to make the oil pit distribution uniform, among other factors, it is important to keep the viscosity of the rolling oil constant during rolling. The viscosity of the rolling oil is basically determined by the type of the rolling oil, but the viscosity is lowered by gradually increasing the rolling oil by the processing heat during rolling. As the viscosity of the rolling oil changes, if the degree to which the rolling oil is pushed into the copper foil surface changes, it leads to variations in the oil pit distribution.
For example, when the rolling oil is kept at around 25 ° C. in the temperature adjustment before rolling, when the rolling oil is sprayed onto the work roll being rolled, heat from the work roll and the like that has risen due to the processing heat is transmitted, It rises to about 40 ° C. If maintained in this state, there is little variation in oil pit distribution and there is no problem with the copper foil shape. However, when the temperature control of the rolling oil is not sufficient and the rolling oil temperature varies beyond 40 ° C., not only the surface properties of the copper foil are likely to vary but also the plate shape is affected. Therefore, in order to adjust the temperature of the rolling oil during rolling to about 40 ° C., it is necessary to comprehensively adjust the rolling oil temperature, the rolling speed, the working degree, etc. before roll injection.
　本発明に係る圧延銅箔を材料とする集電体とその上に形成された活物質層によって構成された負極を用いて、慣用手段によりリチウムイオン電池を作製することができる。リチウムイオン電池には、電解質中のリチウムイオンが電気伝導を担うリチウムイオン一次電池用及びリチウムイオン二次電池が含まれる。負極活物質としては、限定的ではないが、炭素、珪素、スズ、ゲルマニウム、鉛、アンチモン、アルミニウム、インジウム、リチウム、酸化スズ、チタン酸リチウム、窒化リチウム、インジウムを固溶した酸化錫、インジウム－錫合金、リチウム－アルミニウム合金、リチウム－インジウム合金等が挙げられる。 A lithium ion battery can be produced by conventional means using a current collector made of a rolled copper foil according to the present invention and an anode composed of an active material layer formed thereon. The lithium ion battery includes a lithium ion primary battery and a lithium ion secondary battery in which lithium ions in the electrolyte are responsible for electrical conduction. Examples of the negative electrode active material include, but are not limited to, carbon, silicon, tin, germanium, lead, antimony, aluminum, indium, lithium, tin oxide, lithium titanate, lithium nitride, indium-tin oxide, indium Examples thereof include a tin alloy, a lithium-aluminum alloy, and a lithium-indium alloy.
　以下、本発明の実施例を示すが、これらは本発明をより良く理解するために提供するものであり、本発明が限定されることを意図するものではない。 Examples of the present invention will be described below, but these are provided for better understanding of the present invention and are not intended to limit the present invention.
＜例１（表面粗さＲａのばらつきの影響）＞
［圧延銅箔の製造］
　タフピッチ銅のインゴットを熱間圧延した後、焼鈍と冷間圧延を繰り返し、最後に冷間圧延を行って圧延方向長さが１０ｍ以上で設定厚み１０μｍの圧延銅箔（Ｎｏ．１～６）を得た。最終冷間圧延において、最終パス直前の１パスにのみ用いたワークロールの表面粗さ、及び最終パスに用いたワークロール表面粗さを表１に示す。用いた圧延油の粘度は７．０ｃＳｔ（４０℃）であり、最終冷間圧延における圧延油の温度は４０℃前後に制御した。ワークロールの表面粗さは、ＪＩＳ　Ｂ０６０１：２００１に従い、接触式の表面粗さ計にて測定した。 <Example 1 (effect of variation in surface roughness Ra)>
[Manufacture of rolled copper foil]
After hot rolling a tough pitch copper ingot, annealing and cold rolling are repeated, and finally cold rolling is performed to obtain a rolled copper foil (No. 1 to 6) having a rolling direction length of 10 m or more and a set thickness of 10 μm. Obtained. Table 1 shows the surface roughness of the work roll used for only one pass immediately before the final pass and the work roll surface roughness used for the final pass in the final cold rolling. The viscosity of the rolling oil used was 7.0 cSt (40 ° C.), and the temperature of the rolling oil in the final cold rolling was controlled around 40 ° C. The surface roughness of the work roll was measured with a contact-type surface roughness meter according to JIS B0601: 2001.
　得られた圧延銅箔をガラス板上に乗せて固定し、レーザーテック社のコンフォーカル顕微鏡ＨＤ１００Ｄを用い、Ｒａavg、ΔＲａ、ＲＳｍavg、及びΔＲＳｍを先述した測定方法に基づいて算出した。結果を表１に示す。 The obtained rolled copper foil was fixed on a glass plate, and Ra avg , ΔRa, RSm avg , and ΔRSm were calculated based on the measurement method described above using a laser tech confocal microscope HD100D. The results are shown in Table 1.
［板厚精度評価］
　圧延銅箔の板厚は、重量法（ＩＰＣ－ＴＭ－６５０）に準拠して測定した。得られた銅箔から任意の１０ｍの圧延方向長さを選択し、これについて１ｍおきに板厚を１０点測定した。各測定点の板厚Ｔは３回測定した平均値を取った。１０点のＴの平均値をＴavg、１０点のＴの最大値をＴmax、１０点のＴの最小値をＴminとした。表１には（Ｔavg－Ｔmin）／Ｔavg及び（Ｔmax－Ｔavg）／Ｔavgの大きい方を「板厚ばらつき（％）」として記載した。 [Thickness accuracy evaluation]
The plate thickness of the rolled copper foil was measured according to the weight method (IPC-TM-650). An arbitrary length of 10 m in the rolling direction was selected from the obtained copper foil, and the thickness was measured at 10 points every 1 m. The plate thickness T at each measurement point was an average value measured three times. The average value of T at 10 points was T avg , the maximum value of T at 10 points was T max , and the minimum value of T at 10 points was T min . In Table 1, the larger of (T avg −T min ) / T avg and (T max −T avg ) / T avg is described as “plate thickness variation (%)”.
　Ｎｏ．１～Ｎｏ．４は発明例であり、板厚のばらつきを１．３％以下に抑えることができた。
　Ｎｏ．５は最終パス直前の１パスの表面粗さが大きかったため、ΔＲａが十分に制御できなかった。Ｎｏ．６は最終パス直前の１パスのワークロールの表面粗さを大きくするかわりに、最終パスのワークロールの表面粗を小さくしたが、依然としてΔＲａが十分に制御できなかった。 No. 1-No. No. 4 is an invention example, and the variation of the plate thickness could be suppressed to 1.3% or less.
No. In No. 5, since the surface roughness of one pass immediately before the final pass was large, ΔRa could not be controlled sufficiently. No. In Example 6, instead of increasing the surface roughness of the work roll of one pass immediately before the final pass, the surface roughness of the work roll of the final pass was reduced, but ΔRa could not be sufficiently controlled.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
＜例２（オイルピットの分布の影響）＞
［圧延銅箔の製造］
　タフピッチ銅のインゴットを熱間圧延した後、焼鈍と冷間圧延を繰り返し、最後に冷間圧延を行って圧延方向長さが１０ｍ以上で設定厚み１０μｍの圧延銅箔（Ｎｏ．７～１２）を得た。最終冷間圧延において、最終パス前まで用いたワークロールの表面粗さＲａを０．０１０μｍ、及び最終パスに用いたワークロール表面粗さＲａを０．０５０μｍとした。用いた圧延油の粘度は７．０ｃＳｔ（４０℃）であり、発明例は、最終冷間圧延中の圧延油の温度を４０℃前後となるように調整した。各種特性評価は例１と同様の方法で行った。試験結果を表２に示す。 <Example 2 (effect of oil pit distribution)>
[Manufacture of rolled copper foil]
After hot rolling a tough pitch copper ingot, annealing and cold rolling were repeated, and finally, cold rolling was performed to obtain a rolled copper foil (No. 7 to 12) having a set thickness of 10 μm or more in a rolling direction length of 10 m or more. Obtained. In the final cold rolling, the surface roughness Ra of the work roll used before the final pass was 0.010 μm, and the work roll surface roughness Ra used for the final pass was 0.050 μm. The viscosity of the rolling oil used was 7.0 cSt (40 ° C.), and in the inventive examples, the temperature of the rolling oil during the final cold rolling was adjusted to be around 40 ° C. Various characteristics were evaluated in the same manner as in Example 1. The test results are shown in Table 2.
　発明例Ｎｏ．７～９は最終圧延機の圧延油の温度管理が４０℃に管理されているため、オイルピットの分布は均一となり、ばらつきは少なく、板厚のばらつきは１．２％未満と小さかった。
　発明例Ｎｏ．１０～１２は、最終冷間圧延機中の圧延油の温度の管理以外は発明例Ｎｏ．７～９と同じ条件で実施した。ここでは最終冷間圧延機中の圧延油の温度の管理を十分には行なわなかったため、４０℃を超えて４５℃程度にまで上昇した。測定では確認できないが局部的には５０℃を超える部分もあったと想定される。その結果、オイルピットの分布は均一化することができず、板厚のばらつきが１．２％を超えるケースが見られた。 Invention Example No. In Nos. 7 to 9, since the temperature control of the rolling oil of the final rolling mill was controlled at 40 ° C., the oil pit distribution was uniform, there was little variation, and the plate thickness variation was as small as less than 1.2%.
Invention Example No. Nos. 10 to 12 are invention example Nos. Except for controlling the temperature of the rolling oil in the final cold rolling mill. The test was carried out under the same conditions as in 7-9. Here, since the temperature of the rolling oil in the final cold rolling mill was not sufficiently controlled, the temperature rose from 40 ° C. to about 45 ° C. Although it cannot be confirmed by measurement, it is assumed that there was a part that exceeded 50 ° C locally. As a result, the distribution of oil pits could not be made uniform, and there was a case where the variation in thickness exceeded 1.2%.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002

Claims (7)

  1. 　圧延平行方向における表面粗さＲａの平均（Ｒａavg）が０．０１～０．１５μｍであり、ΔＲａ＝Ｒａmax－Ｒａminが０．０２５μｍ以下であることを特徴とするリチウムイオン電池集電体用銅箔。 Lithium ion battery current collector characterized by having an average (Ra avg ) of surface roughness Ra in the rolling parallel direction of 0.01 to 0.15 μm and ΔRa = Ra max −Ra min of 0.025 μm or less Copper foil.
  2. 　銅箔の板厚が５～２０μｍであることを特徴とする請求項１に記載のリチウムイオン電池集電体用銅箔。 2. The copper foil for a lithium ion battery current collector according to claim 1, wherein the copper foil has a thickness of 5 to 20 μm.
  3. 　銅箔の板厚の最大値（ｔmax）と板厚の平均値（ｔavg）との差、又は最小値（ｔmin）と板厚の平均値（ｔavg）との差のいずれか大きい方の値の、板厚の平均値（ｔavg）に対する割合が１．３％以下であることを特徴とする請求項１又は２に記載のリチウムイオン電池集電体用銅箔。 The difference between the maximum value (t max ) of the copper foil thickness and the average value (t avg ) of the plate thickness, or the difference between the minimum value (t min ) and the average value (t avg ) of the plate thickness, whichever is greater 3. The copper foil for a lithium ion battery current collector according to claim 1, wherein a ratio of the first value to the average value (t avg ) of the plate thickness is 1.3% or less.
  4. 　圧延平行方向における表面粗さＲＳｍの平均（ＲＳｍavg）に対するΔＲＳｍ＝ＲＳｍmax－ＲＳｍminの比（ΔＲＳｍ／ＲＳｍavg）が０．５以下であることを特徴とする請求項１～３の何れか一項記載のリチウムイオン電池集電体用銅箔。 The ratio (ΔRSm / RSm avg ) of ΔRSm = RSm max -RSm min to the average (RSm avg ) of the surface roughness RSm in the rolling parallel direction is 0.5 or less, or any one of claims 1 to 3 The copper foil for lithium ion battery collectors according to one item.
  5. 　リチウムイオン二次電池負極集電体用である請求項１～４何れか一項記載のリチウムイオン電池集電体用銅箔。 The copper foil for a lithium ion battery current collector according to any one of claims 1 to 4, which is used for a negative electrode current collector of a lithium ion secondary battery.
  6. 　請求項１～５何れか一項記載の銅箔を集電体として備えたリチウムイオン電池。 A lithium ion battery comprising the copper foil according to any one of claims 1 to 5 as a current collector.
  7. 　最終冷間圧延工程において、最終パスに用いられるワークロールの表面粗さＲａが０．０３μｍ以上であり、最終パス直前の１パスに用いられるワークロールの表面粗さＲａが０．０３μｍ未満であることを特徴とするリチウムイオン電池集電体用銅箔の製造方法。 In the final cold rolling step, the surface roughness Ra of the work roll used for the final pass is 0.03 μm or more, and the surface roughness Ra of the work roll used for one pass immediately before the final pass is less than 0.03 μm. The manufacturing method of the copper foil for lithium ion battery collectors characterized by the above-mentioned.
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JP5226027B2 (en) 2013-07-03
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CN102812585A (en) 2012-12-05
CN102812585B (en) 2015-06-17

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