JP4518850B2 - Secondary battery electrode plate, method for producing the same, and secondary battery using the electrode plate - Google Patents

Secondary battery electrode plate, method for producing the same, and secondary battery using the electrode plate Download PDF

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JP4518850B2
JP4518850B2 JP2004197627A JP2004197627A JP4518850B2 JP 4518850 B2 JP4518850 B2 JP 4518850B2 JP 2004197627 A JP2004197627 A JP 2004197627A JP 2004197627 A JP2004197627 A JP 2004197627A JP 4518850 B2 JP4518850 B2 JP 4518850B2
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electrode plate
secondary battery
tape
positive electrode
insulating tape
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JP2006019199A (en
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敬太 細川
雅統 大木
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Sanyo Electric 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Description

本発明は、二次電池用電極板、その製造方法及び前記電極板を用いた二次電池に関し、特にリチウム非水電解質二次電池等の渦巻状電極群を備えた電池用の電極板、その製造方法及び前記電極板を用いた二次電池に関する。さらに詳しくは、本発明は電池の温度が高くなった際にも短絡等の故障の発生が少ない二次電池用電極板、その製造方法及び前記電極板を用いた二次電池に関する。   The present invention relates to an electrode plate for a secondary battery, a method for producing the same, and a secondary battery using the electrode plate, and more particularly, an electrode plate for a battery having a spiral electrode group such as a lithium nonaqueous electrolyte secondary battery, The present invention relates to a manufacturing method and a secondary battery using the electrode plate. More specifically, the present invention relates to an electrode plate for a secondary battery that is less likely to cause a failure such as a short circuit even when the temperature of the battery becomes high, a manufacturing method thereof, and a secondary battery using the electrode plate.

二次電池の用途は、パーソナルコンピュータ（ＰＣ）、携帯電話、自動車、電気自動車（ＥＶ）、ハイブリッド車（ＨＥＶ）、電動アシスト自転車、電動工具等広範囲に亘り、それらに使用される電池への要求仕様は年々厳しくなり、より一層の特性向上のため、高エネルギー密度化、自己放電抑制、長寿命化などの様々な改良が行われている。   Secondary batteries are used in a wide range of applications such as personal computers (PCs), mobile phones, automobiles, electric vehicles (EV), hybrid vehicles (HEV), electric assist bicycles, electric tools, and so on. The specifications have become stricter year by year, and various improvements such as higher energy density, suppression of self-discharge, and longer life have been made to further improve the characteristics.

近年では、携帯型の電子機器の急速な普及に伴い、特に小型薄型化したもの、高容量でサイクル特性が優れ、性能の安定したものが要求されており、軽量かつ高容量で高エネルギー密度が得られることから負極に水素吸蔵合金を用いた金属水素化物二次電池や、特に他の電池に比べて高エネルギー密度であるリチウム非水電解質二次電池が注目され、二次電池市場で大きな伸びを示している。   In recent years, with the rapid spread of portable electronic devices, there has been a demand for particularly compact, thin, high capacity, excellent cycle characteristics, stable performance, light weight, high capacity and high energy density. As a result, metal hydride secondary batteries using a hydrogen storage alloy for the negative electrode and lithium non-aqueous electrolyte secondary batteries, which have a higher energy density than other batteries, are attracting attention, and the secondary battery market is growing significantly. Is shown.

このうち、金属水素化物二次電池は、例えば下記特許文献１及び２に開示されているように、水素吸蔵合金粉末にポリテトラフルオロエチレンを結着剤として添加し、均一に混練した混合物を圧延の後、集電体の両面に配置して圧着し、乾燥することにより水素吸蔵合金電極からなる負極を作製し、この水素吸蔵合金電極からなる負極を公知のニッケル正極と組み合わせ、これら正負極の間にセパレータを介して巻回して渦巻状電極群を作製し、角型電池の場合はさらに渦巻状電極群を押し潰して偏平状とし、電池外装体に収納後、電解液を注液し、封口することにより作製されている。   Among these, as disclosed in Patent Documents 1 and 2 below, for example, a metal hydride secondary battery is obtained by rolling a mixture obtained by adding polytetrafluoroethylene to a hydrogen storage alloy powder as a binder and uniformly kneading. After that, the negative electrode made of a hydrogen storage alloy electrode was prepared by arranging the pressure collector on both sides of the current collector and then pressing and drying, and combining the negative electrode made of this hydrogen storage alloy electrode with a known nickel positive electrode. Wound through a separator to produce a spiral electrode group, and in the case of a square battery, further crush the spiral electrode group to make it flat, and after storing it in the battery outer package, injecting an electrolyte, It is made by sealing.

また、リチウム非水電解質二次電池は、短冊状の銅箔等からなる負極集電体の両面に負極用活物質合剤が塗布されて形成された負極と、短冊状のアルミニウム箔等からなる正極集電体の両面に正極用活物質合剤が塗布されて形成された正極との間に微多孔性ポリプロピレンフィルム等からなるセパレータを介して互いに絶縁した状態で円柱状又は楕円形状に巻回して渦巻状電極群を作製し、角型電池の場合はさらに渦巻状電極群を押し潰して偏平状に成型し、次いで、上記負極及び正極の各所定部分にそれぞれ負極リード及び正極リードを溶接して所定形状の外装体に収納された構成を有している。     Further, the lithium non-aqueous electrolyte secondary battery is composed of a negative electrode formed by applying a negative electrode active material mixture on both surfaces of a negative electrode current collector made of a strip-shaped copper foil, and a strip-shaped aluminum foil. It is wound into a cylindrical or elliptical shape in a state of being insulated from each other through a separator made of a microporous polypropylene film or the like between a positive electrode formed by applying a positive electrode active material mixture on both surfaces of a positive electrode current collector In the case of a rectangular battery, the spiral electrode group is further crushed and formed into a flat shape, and then a negative electrode lead and a positive electrode lead are welded to the predetermined portions of the negative electrode and the positive electrode, respectively. And having a configuration housed in an exterior body of a predetermined shape.

ところが、このような渦巻状電極群の製造に際しては、負極材及び正極材から巻芯に巻回するための負極及び正極が切り出されるが、その際に負極及び正極の切断端部、すなわち金属材からなる負極芯体及び正極芯体の切断端部にばりが発生する。このばりが発生している状態で渦巻状電極群を押しつぶし成型すると、ばりにより隣接するセパレータが突き破られ、このばりを介して負極と正極とが電気的に導通して短絡回路が形成される。するとこの短絡回路により、電池はその使用中に異常な熱を発生し、容量低下を招き、しかも電池寿命を短くする原因にもなっていた。   However, in the production of such a spiral electrode group, the negative electrode and the positive electrode for winding around the core are cut out from the negative electrode material and the positive electrode material. At that time, the cut ends of the negative electrode and the positive electrode, that is, the metal material A flash occurs at the cut ends of the negative electrode core and the positive electrode core. When the spiral electrode group is crushed and molded in a state where the flash is generated, the adjacent separator is broken through by the flash, and the negative electrode and the positive electrode are electrically connected through the flash to form a short circuit. . As a result, the short-circuit causes the battery to generate abnormal heat during use, leading to a reduction in capacity and shortening the battery life.

リチウムイオン電池に代表される非水電解質二次電池においては、充電時に正極活物質から放出されたリチウムイオンを負極活物質に円滑に吸蔵するために、負極合剤層は必ず正極合剤塗布部を越えてセパレータを介して対向していなければならない。したがって、非水電解質二次電池には上述の正極の活物質合剤未塗布部分と負極の負極合剤塗布部分が対向している部分は少なからず存在し、この部分での導電性粒子が原因となる内部短絡対策は急務である。   In a non-aqueous electrolyte secondary battery typified by a lithium ion battery, the negative electrode mixture layer must be a positive electrode mixture application part in order to smoothly occlude lithium ions released from the positive electrode active material during charging into the negative electrode active material. Must face each other across the separator. Therefore, in the non-aqueous electrolyte secondary battery, there are not a few portions where the active material mixture uncoated portion of the positive electrode and the negative electrode mixture coated portion of the negative electrode face each other, and the conductive particles in this portion are the cause. There is an urgent need for internal short circuit countermeasures.

そのため、例えば、下記特許文献３には、正極、セパレータ、負極のうち少なくとも正極リードに対向する部分の負極に、正極と負極とをセパレータを介在させて重ねた状態で形成される渦巻状電極群の製造時に、負極を位置決めし、渦巻状電極群が形成される際に正極との短絡の原因となる正極側及び／又は負極側に生じているばりの高さよりも厚い所定の絶縁性テープを、位置決めされた負極の少なくとも一方の面における正極との短絡想定位置に貼付させた非水電解質二次電池が開示されている。この下記特許文献３に開示されている非水電解質二次電池の電極の具体例を図５を用いて説明する。   Therefore, for example, Patent Document 3 below discloses a spiral electrode group formed by stacking a positive electrode and a negative electrode with a separator interposed between at least a portion of a positive electrode, a separator, and a negative electrode facing a positive electrode lead. During the manufacture of the electrode, a predetermined insulating tape thicker than the height of the flash produced on the positive electrode side and / or the negative electrode side, which causes a short circuit with the positive electrode when the spiral electrode group is formed, is formed. In addition, a non-aqueous electrolyte secondary battery is disclosed in which it is pasted at a short-circuit expected position with the positive electrode on at least one surface of the positioned negative electrode. The specific example of the electrode of the nonaqueous electrolyte secondary battery currently disclosed by the following patent document 3 is demonstrated using FIG.

図５は、下記特許文献３に開示されている非水電解質二次電池の渦巻状電極群の構成を示す。巻芯７０はシート状の２枚の絶縁性セパレータ７２と７４の一端近傍を折り返すように挟んでいる。正極芯体７６は、中央部の両面に正極活物質合剤層７８が形成されており、先端ＣＴの近傍の両面には正極活物質合剤層が形成されておらず、正極芯体部が露出している。正極リード８０は、正極芯体７６の上の正極芯体露出部に接合されている。負極芯体８２は、中央部の両面に負極活物質合剤層８４が形成されており、先端ＣＴの近傍の両面には負極合剤が塗布されておらず、負極芯体露出部となっている。   FIG. 5 shows a configuration of a spiral electrode group of a nonaqueous electrolyte secondary battery disclosed in Patent Document 3 below. The core 70 is sandwiched between two sheet-like insulating separators 72 and 74 so as to be folded back in the vicinity of one end. In the positive electrode core body 76, a positive electrode active material mixture layer 78 is formed on both surfaces of the central portion, and no positive electrode active material mixture layer is formed on both surfaces in the vicinity of the tip CT. Exposed. The positive electrode lead 80 is joined to the exposed portion of the positive electrode core body on the positive electrode core body 76. The negative electrode core body 82 has a negative electrode active material mixture layer 84 formed on both surfaces of the central portion, and the negative electrode mixture is not applied to both surfaces in the vicinity of the tip CT, and becomes a negative electrode core exposed portion. Yes.

正極芯体７６は巻芯７０とセパレータ７２の間に挟まれて巻回され、負極芯体８２は２枚のセパレータ７２と７４の間に挟まれて巻回される。負極芯体８２の先端ＣＴがセパレータ７２を挟んで対向する正極芯体７６の部分の巻芯７０側の面に正極リード８０が接合されている。すなわち、正極芯体７６上で正極リード８０が接合されている部分は、セパレータ７２を挟んで負極芯体８２の先端ＣＴの端部と対向している。   The positive electrode core body 76 is sandwiched and wound between the core 70 and the separator 72, and the negative electrode core body 82 is sandwiched and wound between the two separators 72 and 74. A positive electrode lead 80 is joined to the surface on the winding core 70 side of the portion of the positive electrode core body 76 where the tip CT of the negative electrode core body 82 is opposed to the separator 72. That is, the portion where the positive electrode lead 80 is bonded on the positive electrode core 76 is opposed to the end portion of the tip CT of the negative electrode core 82 with the separator 72 interposed therebetween.

かかる構成のものにおいては、正極芯体７６と負極芯体８２が短絡してしまうのを防止するために、以下の構成が採用されている。すなわち、
（１）正極リード８０が接合された正極芯体７６の部分のうちセパレータ７２を挟んで負極シート８６の先端ＣＴの周辺部分に対向する正極芯体７６の面を絶縁性材料８８で被覆する。
（２）正極リード８０が接合された正極芯体７６の部分とそれに対向する負極シート８６の先端ＣＴの周辺部分の間にあるセパレータ７２の部分のうち正極シート９０又は負極シート８６のいずれかに対向する面を絶縁性材料９２で被覆する。
（３）正極リード８０が接合された正極芯体７６の部分にセパレータ７２を挟んで対向する負極シート８６の先端ＣＴの周辺部分の面を絶縁性材料９４で被覆する。 In such a configuration, the following configuration is employed to prevent the positive electrode core 76 and the negative electrode core 82 from being short-circuited. That is,
(1) The surface of the positive electrode core body 76 facing the peripheral portion of the tip CT of the negative electrode sheet 86 with the separator 72 interposed therebetween is covered with the insulating material 88 among the positive electrode core body 76 portion to which the positive electrode lead 80 is bonded.
(2) Of the portion of the separator 72 between the portion of the positive electrode core body 76 to which the positive electrode lead 80 is joined and the peripheral portion of the tip CT of the negative electrode sheet 86 facing the positive electrode sheet 80, The opposing surfaces are covered with an insulating material 92.
(3) The surface of the peripheral portion of the tip CT of the negative electrode sheet 86 opposed to the portion of the positive electrode core 76 to which the positive electrode lead 80 is bonded with the separator 72 interposed therebetween is covered with the insulating material 94.

この場合、上記の３つの手段のうちの１つを施せばよい。すなわち、絶縁性材料８８で正極芯体７６を被覆すれば、正極リード８０のバリは絶縁性材料８８に保護され、セパレータ７２は破損しない。また、絶縁性材料９４で負極芯体８２を被覆すれば、正極リード８０のバリがセパレータ７２を貫通しても絶縁性材料９４によって保護される。さらに、絶縁性材料９２をセパレータ７２のいずれかの面に被覆した場合にも、上記と同様な作用が生じる。以上が絶縁性材料８８、９２、９４の作用であるが、この絶縁性材料８８、９２、９４は樹脂を塗布又は塗り付けたり、絶縁性テープを貼り付けたりすれば良いが、粘着性絶縁性テープが好ましいとされている。   In this case, one of the above three means may be applied. That is, if the positive electrode core 76 is covered with the insulating material 88, the burrs of the positive electrode lead 80 are protected by the insulating material 88, and the separator 72 is not damaged. Further, if the negative electrode core 82 is covered with the insulating material 94, even if the burr of the positive electrode lead 80 penetrates the separator 72, it is protected by the insulating material 94. Further, when the insulating material 92 is coated on any surface of the separator 72, the same action as described above occurs. The above is the action of the insulating materials 88, 92, and 94. The insulating materials 88, 92, and 94 may be coated or coated with resin or attached with insulating tape. Tape is preferred.

上述のような従来例によれば、正極及び負極の作製時に生じたばりによる問題点は十分に解決することができるはずのものであるが、ばりの発生を極限まで抑制させて製造された渦巻状電極群を有する非水電解質二次電池、特に角型の非水電解質二次電池には依然として正極及び負極間の短絡現象が見受けられた。   According to the conventional example as described above, the problem caused by the flash generated during the production of the positive electrode and the negative electrode should be able to be sufficiently solved, but the spiral produced by suppressing the generation of the flash to the limit. In the non-aqueous electrolyte secondary battery having the electrode group, particularly the rectangular non-aqueous electrolyte secondary battery, the short circuit phenomenon between the positive electrode and the negative electrode was still observed.

この原因は、電極のばりだけに起因するものではなく、製造工程における活物質合剤の脱落や製造装置の磨耗により、正極の活物質合剤未塗布部分上すなわち芯体露出部上に導電性の粒子が付着し、この導電性粒子が渦巻状電極群を押しつぶし成型した際や、電池の充放電による電極板の膨張によりセパレータを突き破り、この導電性粒子を介して負極と正極とが電気的に導通して短絡回路が形成されることに起因するものであり、この場合、この短絡は、図５の符号９９に示した正極の活物質合剤未塗布部分と負極の負極合剤塗布部分が対向している部分において非常に高率で発生する。   This cause is not only due to the flash of the electrode, but due to the dropping of the active material mixture in the manufacturing process and the wear of the manufacturing equipment, the conductive material on the positive electrode active material mixture uncoated part, that is, on the core exposed part When the conductive particles crush and form the spiral electrode group or when the electrode plate expands due to charge / discharge of the battery, the separator and the positive electrode are electrically connected through the conductive particles. In this case, this short circuit is caused by the positive electrode active material mixture uncoated portion and the negative electrode negative electrode mixture coated portion indicated by reference numeral 99 in FIG. Is generated at a very high rate in the facing part.

加えて、従来から短絡防止に用いられている粘着性絶縁テープは、電極板切断工程や電極板成型工程などの電池製造工程において粘着剤が製造装置に付着するので、頻繁に装置を清掃する必要があり、生産性が低下するという問題点が存在している。   In addition, adhesive insulating tapes that have been used to prevent short circuits from the past have to be cleaned frequently because the adhesive adheres to the manufacturing equipment in the battery manufacturing process such as the electrode plate cutting process and the electrode plate molding process. There is a problem that productivity decreases.

そこで、本願の出願人は、上述のような問題点を解決し、電極間の内部短絡が生じ難く、また電池製造工程の清掃頻度を減らすことができるようになす目的で、図６（ａ）及び図６（ｂ）に示すように、電極板の活物質合剤塗布部分と未塗布部分とに跨ってポリプロビレンやポリエチレンなどの高分子材料からなる基材の片面に室温では粘着性がほとんどないが温度が上昇すると粘着性が増す低温熱可塑性糊材を使用した熱溶着性絶縁性テープ（以下、「熱溶着性テープ」という。）１００からなる絶縁層を設けた「非水電解質二次電池、及びそれに使用する電極の製造方法」の発明を既に特願２００３−０４９９５８号（以下、「先願」という。）として特許出願している。なお、図６（ａ）は先願発明で使用されている一方の電極板の長さ方向の横断面図であり、図６（ｂ）は平面図である。また、図６（ａ）及び図６（ｂ）においては、図５に記載の非水電解質二次電池の渦巻状電極群と同一の構成部分には同じ参照符号を付与することとしてその詳細な説明は省略する。   Accordingly, the applicant of the present application solves the above-described problems, makes it difficult for internal short-circuiting between the electrodes, and reduces the frequency of cleaning in the battery manufacturing process. And as shown in FIG.6 (b), there is almost no adhesiveness at room temperature on the one side of the base material which consists of polymeric materials, such as a polypropylene and polyethylene, across the active material mixture application | coating part of an electrode plate, and an unapplied part. "Non-aqueous electrolyte secondary battery" provided with an insulating layer made of a heat-welding insulating tape (hereinafter referred to as "heat-welding tape") 100 using a low-temperature thermoplastic paste that increases in adhesiveness when the temperature rises And the manufacturing method of the electrode used therefor have already been filed as Japanese Patent Application No. 2003-049958 (hereinafter referred to as “prior application”). 6A is a cross-sectional view in the length direction of one electrode plate used in the prior invention, and FIG. 6B is a plan view. 6 (a) and 6 (b), the same components as those of the spiral electrode group of the nonaqueous electrolyte secondary battery shown in FIG. Description is omitted.

前記先願の明細書及び図面に開示されている非水電解質二次電池の渦巻状電極群を使用すると、一応製造時の電極間の内部短絡が生じ難く、また電池製造工程の清掃頻度を減らすことができるが、大電流充放電時に電池が発熱して高温状態となった場合や外部から熱を受けて電池が高温に加熱された際に電極板間の短絡が生じる場合があることが見出された。   When the spiral electrode group of the non-aqueous electrolyte secondary battery disclosed in the specification and drawings of the prior application is used, internal short-circuiting between the electrodes at the time of manufacturing is less likely to occur, and the cleaning frequency of the battery manufacturing process is reduced. However, it can be seen that a short circuit between the electrode plates may occur when the battery generates heat during high-current charge / discharge and becomes hot or when the battery is heated to high temperature due to external heat. It was issued.

本発明者等はこの原因につき種々検討を重ねた結果、従来の短絡防止用として使用されている熱溶着性テープ１００は熱溶着性テープコイルから繰り出されて電極板の幅方向に付着されているが、この熱溶着性テープ１００の基材はその製造方法に起因してある一定の熱を受けると、例えば図７に示したように、単軸方向（例えば、図７の矢印の方向）に熱収縮し易い性質がある（以下、このような収縮しやすい単軸を「易収縮軸」という。）ため、熱溶着性テープ１００の貼付後に電極板に熱が加えられると、熱溶着性テープ１００の基材が収縮して、前述の境界部が大幅に露出してしまうことによるものであることを見出した。なお、図７は電極板に熱が加えられた後の図６（ｂ）に対応する平面図であり、さらに、図５に記載の非水電解質二次電池の渦巻状電極群と同一の構成部分には同じ参照符号を付与することとしてその詳細な説明は省略する。   As a result of various investigations on this cause, the present inventors have conducted heat-welding tape 100 used for conventional short-circuit prevention to be fed out from the heat-welding tape coil and attached in the width direction of the electrode plate. However, when the base material of the heat-welding tape 100 is subjected to a certain amount of heat due to the manufacturing method thereof, for example, as shown in FIG. 7, in the uniaxial direction (for example, the direction of the arrow in FIG. 7). Since it has the property of being easily heat-shrinkable (hereinafter referred to as “easy-shrinkable axis”), when heat is applied to the electrode plate after application of the heat-welding tape 100, the heat-welding tape. It has been found that this is due to the fact that 100 base materials contract and the above-mentioned boundary portion is significantly exposed. 7 is a plan view corresponding to FIG. 6B after heat is applied to the electrode plate, and further, the same configuration as the spiral electrode group of the nonaqueous electrolyte secondary battery shown in FIG. The same reference numerals are assigned to the parts, and detailed description thereof is omitted.

このような熱溶着性テープの基材に生じる現象は、高分子材料製テープは、例えば下記特許文献５に開示されているように、通常幅方向に引き裂き易いようにするために長さ方向に延伸して製造されているが、その結果として延伸方向に熱収縮し易い性質、即ち長さ方向が易収縮軸となってしまうために生じるものである。   The phenomenon that occurs in the base material of such a heat-welding tape is that, as disclosed in, for example, Patent Document 5 below, a tape made of a polymer material is usually stretched in the length direction so as to be easily torn in the width direction. Although it is manufactured by stretching, it results from the property that it easily contracts by heat in the stretching direction, that is, the length direction becomes the easy contraction axis.

特開平０７−１５３４８３号公報Japanese Patent Application Laid-Open No. 07-153484 特開平０５−１０１８２２号公報Japanese Patent Laid-Open No. 05-101822 特開平１０−２４１７３７号公報（段落［００１８］〜［００２７］、［００４０］〜［００５０］、図１、図５、図７）JP-A-10-241737 (paragraphs [0018] to [0027], [0040] to [0050], FIG. 1, FIG. 5, FIG. 7) 特願２００３−０４９９５８号（特許請求の範囲、段落［００３２］〜［００３６］、図６）Japanese Patent Application No. 2003-049958 (claims, paragraphs [0032] to [0036], FIG. 6) 特開平１１−３４９９０７号公報（段落［０００３］、［００２０］）JP 11-349907 A (paragraphs [0003] and [0020])

そこで本発明は、このような従来技術が抱える課題を解決するためになされたものであり、本発明の第１の目的は、電極板の活物質合剤塗布部と未塗布部との境界付近での短絡防止用に絶縁性テープを使用した際に、電極板に熱が加えられて絶縁性テープが熱収縮しても、電極板の活物質合剤塗布部と未塗布部との境界付近を有効に被覆して短絡防止機能を維持できるようになした二次電池用電極板を提供することにある。   Therefore, the present invention has been made to solve such problems of the prior art, and the first object of the present invention is near the boundary between the active material mixture coated portion and the uncoated portion of the electrode plate. When insulating tape is used to prevent short-circuiting at the electrode, even if heat is applied to the electrode plate and the insulating tape is thermally contracted, the vicinity of the boundary between the active material mixture coated portion and uncoated portion of the electrode plate It is an object to provide an electrode plate for a secondary battery that can effectively cover the surface and maintain a short-circuit prevention function.

また、本発明の第２の目的は、前記二次電池用電極板を用いた二次電池を提供することにある。   The second object of the present invention is to provide a secondary battery using the electrode plate for a secondary battery.

また、本発明の第３の目的は、前記二次電池用電極板の製造方法を提供することにある。   The third object of the present invention is to provide a method for producing the electrode plate for a secondary battery.

さらに、本発明の第４の目的は、前記二次電池用電極板の製造方法により製造された電極板を用いた二次電池を提供することにある。   Furthermore, the fourth object of the present invention is to provide a secondary battery using an electrode plate manufactured by the method for manufacturing a secondary battery electrode plate.

本発明の上記目的は以下の構成により解決し得る。すなわち、請求項１に記載の二次電池用電極板の発明は、電極板の活物質合剤塗布部と未塗布部との境界部が絶縁性テープで被覆されており、かつその絶縁性テープの易収縮軸方向が電極板の長さ方向であることを特徴とする。   The above object of the present invention can be solved by the following configuration. That is, in the invention of the electrode plate for a secondary battery according to claim 1, the boundary portion between the active material mixture coated portion and the uncoated portion of the electrode plate is covered with the insulating tape, and the insulating tape The easy contraction axis direction is the length direction of the electrode plate.

この場合、電極板としては、ニッケル水素二次電池用電極板やリチウム非水電解質二次電池用電極等、対となる他の電極板とセパレータを介して渦巻状に巻回して渦巻状電極群を構成して使用される二次電池用電極板に対して等しく適用できる。また、絶縁性テープとしては粘着性絶縁性テープも一応使用し得る。   In this case, the electrode plate is a spiral electrode group that is wound in a spiral shape through a separator and another electrode plate, such as an electrode plate for a nickel hydride secondary battery or an electrode for a lithium nonaqueous electrolyte secondary battery, and a separator. The present invention can be equally applied to the electrode plate for a secondary battery used in the configuration. In addition, an adhesive insulating tape can be used as the insulating tape.

また、請求項２に記載の発明は、前記請求項１に記載の二次電池用電極板において、前記絶縁性テープは、その一面に低温熱可塑性糊材が付着されており、前記電極板の活物質合剤塗布部と未塗布部との境界部に熱溶着されていることを特徴とする・   The invention according to claim 2 is the electrode plate for a secondary battery according to claim 1, wherein the insulating tape has a low-temperature thermoplastic paste attached to one surface thereof, It is characterized by being heat-welded at the boundary between the active material mixture coated part and the uncoated part.-

この場合、前記絶縁性テープは、基材としてポリエチレン、ポリプロピレン等のポリオエレフィン、ポリ塩化ビニル、ポリエチレンテレフタレート等のポリエステル、ポリイミド、ポリアミド、ポリフェニレンサルファイド等の樹脂材料からなるものを使用でき、その一面に貼付する糊材として、室温では粘着性がほとんどなく、６０〜１２０℃、好ましくは７０〜１００℃で接着性が増す糊材、たとえば、ＥＶＡ（エチレン酢酸ビニル共重合体）、ＥＥＡ（エチレンエチルアクリレート）、ＥＭＡＡ（エチレンメタクリル酸）等を使用することができる。   In this case, the insulating tape can be made of a resin material such as polyester, polyimide, polyamide, polyphenylene sulfide, polyester such as polyethylene elefin, polyethylene chloride, polyethylene terephthalate, etc. As a paste material to be affixed to a paste, a paste material that has almost no adhesiveness at room temperature and has increased adhesion at 60 to 120 ° C., preferably 70 to 100 ° C., for example, EVA (ethylene vinyl acetate copolymer), EEA (ethylene ethyl) Acrylate), EMAA (ethylene methacrylic acid), and the like.

また、請求項３に記載の二次電池の発明は、前記請求項１又は２に記載の二次電池用電極板が対となる他の電極板とセパレータを介して渦巻状に巻回された渦巻状電極群を有し、前記渦巻状電極群が外装体内に封入されていることを特徴とする。この場合、外装体として、金属製外装缶やアルミニウムラミネート外装体等、任意のものを適宜選択して使用し得る。   Moreover, in the invention of the secondary battery according to claim 3, the electrode plate for the secondary battery according to claim 1 or 2 is wound in a spiral shape through another electrode plate and a separator as a pair. It has a spiral electrode group, and the spiral electrode group is enclosed in an exterior body. In this case, as the exterior body, an arbitrary body such as a metal exterior can or an aluminum laminate exterior body can be appropriately selected and used.

また、請求項４に記載の二次電池用電極板の製造方法の発明は、次の（１）〜（４）の各工程を含むこと特徴とする。
（１）所定の電極板の幅よりも広い導電性芯体の少なくとも一方の表面に、前記所定の電極板の幅より広くかつ所定の長さに亘って活物質合剤を塗布する工程、
（２）一面に糊材が付着された絶縁性テープから、電極板の所定の幅長より広い絶縁性テープを得る工程、
（３）前記電極板の活物質合剤塗布部と未塗布部との境界部を覆い、前記絶縁性テープの易収縮軸方向が前記電極板の長さ方向となるように、前記絶縁性テープを貼付する工程、
（４）次いで、前記電極板と前記絶縁性テープとを同時に切断して、復数の所定の電極板を形成する工程。 Moreover, the invention of the manufacturing method of the electrode plate for secondary batteries of Claim 4 includes each process of following (1)-(4), It is characterized by the above-mentioned.
(1) A step of applying an active material mixture over a predetermined length that is wider than the predetermined electrode plate, on at least one surface of the conductive core wider than the predetermined electrode plate;
(2) A step of obtaining an insulating tape wider than a predetermined width of the electrode plate from an insulating tape having a glue material attached to one surface;
(3) The insulating tape covers a boundary portion between the active material mixture application portion and the non-application portion of the electrode plate, and the easy contraction axis direction of the insulating tape is the length direction of the electrode plate. A process of applying,
(4) Next, the step of simultaneously cutting the electrode plate and the insulating tape to form a predetermined number of electrode plates.

また、請求項５に記載の発明は、前記請求項４に記載の二次電池用電極板の製造方法において、前記糊材は低温熱可塑性の糊材であって、前記（３）の工程における絶縁性テープを貼付する工程を熱溶着法により行うことを特徴とする。   The invention according to claim 5 is the method for producing an electrode plate for a secondary battery according to claim 4, wherein the paste material is a low-temperature thermoplastic paste material, and is in the step (3). The step of applying the insulating tape is performed by a heat welding method.

さらに、請求項６に記載の発明は、前記請求項４に記載の二次電池用電極板の製造方法において、前記（２）及び（３）の工程を、加熱手段を備えるとともに吸着ヘッドを兼ねている金属製本体と、前記金属製本体に取り付けられた可動式テープカット刃とを備えたテープ貼付治具を用いて行うことを特徴とする。   Furthermore, the invention according to claim 6 is the method for manufacturing an electrode plate for a secondary battery according to claim 4, wherein the steps (2) and (3) are provided with heating means and also serve as a suction head. It is characterized by using a tape sticking jig provided with a metal main body and a movable tape cutting blade attached to the metal main body.

本発明は、上記の構成を備えることにより以下に述べるような優れた効果を奏する。すなわち、請求項１の発明によれば、電極板の活物質合剤塗布部と未塗布部との境界部を被覆する絶縁性テープが、その易収縮軸方向が電極板の長さ方向となるように貼付されているので、テープの貼付後に電極板に熱が加えられてテープが収縮した場合でも、テープを従来のような易収縮軸方向が電極板の幅方向になるように貼り付けた時と比べ、前述の境界部の露出を抑えることができる。そのため、この二次電池用電極板を用いて製造された二次電池は、大電流充放電等により使用時に高温となっても、あるいは高温条件下に放置された場合であっても、内部短絡を起こすことが少なくなる。   The present invention provides the following excellent effects by having the above configuration. That is, according to the invention of claim 1, the insulating tape that covers the boundary portion between the active material mixture application portion and the non-application portion of the electrode plate has the easy contraction axis direction as the length direction of the electrode plate. Even when heat is applied to the electrode plate after the tape is applied and the tape shrinks, the tape is attached so that the easy-shrink axis direction is the width direction of the electrode plate as in the past. Compared to the time, exposure of the aforementioned boundary portion can be suppressed. Therefore, the secondary battery manufactured using the electrode plate for the secondary battery can be internally short-circuited even when it is used at a high temperature due to large current charge / discharge, etc. Is less likely to occur.

また、請求項２の発明によれば、粘着性絶縁性テープのような粘着性を有する糊材が存在していないために、二次電池用電極板を製造する際に絶縁性テープを貼付するための糊材のプレス機等への付着を抑制することが可能となり、また、糊材に低温熱可塑性糊材を使用しているので、室温での糊材の粘着性を抑制できるから、二次電池用電極板の製造装置に糊材の付着を抑制できるようになる。   According to the invention of claim 2, since there is no adhesive material having adhesiveness such as an adhesive insulating tape, the insulating tape is applied when manufacturing the electrode plate for the secondary battery. It is possible to suppress adhesion of the adhesive material to a press or the like, and since the low-temperature thermoplastic adhesive material is used for the adhesive material, the adhesiveness of the adhesive material at room temperature can be suppressed. It becomes possible to suppress adhesion of the paste material to the production apparatus for the secondary battery electrode plate.

また、請求項３の発明によれば、製造歩留まりが高く、内部短絡が極めて減少した信頼性の高い二次電池を得ることができる。   In addition, according to the invention of claim 3, it is possible to obtain a highly reliable secondary battery having a high manufacturing yield and extremely reduced internal short circuit.

また、請求項４の発明によれば、容易に前記請求項１に記載の二次電池用電極板を製造することができるとともに、導電性芯体に複数枚分の活物質合剤を塗布した後に、絶縁性テープを所定形状の電極板に切断するので、複数の電極板を纏めて加工することができ、生産性を上げることができる。   According to the invention of claim 4, the electrode plate for a secondary battery according to claim 1 can be easily manufactured, and a plurality of active material mixtures are applied to the conductive core. Later, since the insulating tape is cut into electrode plates having a predetermined shape, a plurality of electrode plates can be processed together, and productivity can be increased.

また、請求項５の発明によれば、絶縁性テープの糊材を加熱溶融させて貼り付けるので、室温での糊材の粘着性を抑制でき、後工程での装置への糊材の付着を抑制できる。   Further, according to the invention of claim 5, since the adhesive material of the insulating tape is heated and melted and pasted, the adhesive property of the adhesive material at room temperature can be suppressed, and adhesion of the adhesive material to the apparatus in the subsequent process can be suppressed. Can be suppressed.

また、請求項６に記載の発明によれば、簡単な構成のテープ貼付治具を使用して効率よく絶縁性テープを切断し、電極板の所定位置へ貼付することができるようになり、製造効率が向上する。   In addition, according to the invention described in claim 6, the insulating tape can be efficiently cut using a tape applying jig having a simple structure, and can be applied to a predetermined position of the electrode plate. Efficiency is improved.

以下、図１〜図４を参照にして本発明の実施例を説明する。ただし、以下に示す実施例は本発明の技術思想を具体化するための二次電池用電極板及びその製造方法の一例をリチウム非水電解質二次電池の正極板の場合を例にとり説明するものであって、本発明をこのリチウム非水電解質二次電池の正極板に特定することを意図するものではなく、リチウム非水電解質二次電池の負極板に対しても、また、ニッケル水素二次電池等の渦巻状電極群を備えた電池の電極板に対しても等しく適用し得るものである。   Embodiments of the present invention will be described below with reference to FIGS. However, in the following examples, an example of a secondary battery electrode plate for embodying the technical idea of the present invention and an example of a method for manufacturing the same will be described taking the case of a positive electrode plate of a lithium non-aqueous electrolyte secondary battery as an example. However, the present invention is not intended to specify the positive electrode plate of the lithium non-aqueous electrolyte secondary battery, and also for the negative electrode plate of the lithium non-aqueous electrolyte secondary battery. The present invention can be equally applied to a battery electrode plate having a spiral electrode group such as a battery.

<正極板の製造>
実施例及び比較例においては、熱溶着性テープの易収縮軸方向の差異による効果の差異を確認するため、以下のようにして、基本的な正極板の構成を全て同一とし、正極板に貼付した熱溶着性テープの易収縮軸方向を電極板の長さ方向としたもの（実施例）及び幅方向としたもの（比較例）についてそれぞれ１０個のサンプルを作製した。この実施例及び比較例のサンプルの具体例を図１に示す。なお、図１（ａ）は実施例に対応する正極板の平面図であり、図１（ｂ）は比較例に対応する正極板の平面図であり、図中の矢印は易収縮軸方向を示している。 <Manufacture of positive electrode plate>
In the examples and comparative examples, in order to confirm the difference in the effect due to the difference in the direction of the easily shrinkable axis of the heat-weldable tape, the basic configuration of the positive electrode plate is all the same as described below, and affixed to the positive electrode plate as follows. Ten samples were prepared for each of the heat-weldable tapes having the easily shrinkable axis direction as the length direction of the electrode plate (Example) and the width direction (Comparative Example). Specific examples of samples of this example and comparative example are shown in FIG. 1A is a plan view of the positive electrode plate corresponding to the embodiment, FIG. 1B is a plan view of the positive electrode plate corresponding to the comparative example, and the arrow in the figure indicates the direction of the easy contraction axis. Show.

これらの実施例及び比較例に対応する正極板１０Ｘ及び１０Ｙは、いずれも正極板の構成として正極芯体１１の両面に一定厚さの正極活物質合剤１２が塗布された構成を備えている点では共通しているが、実施例に対応する正極板１０Ｘでは一方の面の正極活物質合剤１２が塗布されている領域と未塗布の領域との境界付近を覆う熱溶着性テープ１３Ｘの易収縮軸が正極板の長さ方向となっている（図１（ａ）参照）のに対し、比較例に対応する正極板１０Ｙでは熱溶着性テープ１３Ｙの易収縮軸が正極板の幅方向となっている（図１（ｂ）参照）点でのみ相違している。   The positive plates 10X and 10Y corresponding to these examples and comparative examples each have a configuration in which a positive electrode active material mixture 12 having a certain thickness is applied to both surfaces of the positive electrode core 11 as a configuration of the positive plate. Although common in respect, the positive electrode plate 10X corresponding to the embodiment of the heat-welding tape 13X that covers the vicinity of the boundary between the area where the positive electrode active material mixture 12 is applied on one side and the area where the positive electrode active material mixture 12 is not applied. Whereas the easy contraction axis is the length direction of the positive electrode plate (see FIG. 1A), in the positive electrode plate 10Y corresponding to the comparative example, the easy contraction axis of the heat-welding tape 13Y is the width direction of the positive electrode plate. (Refer to FIG. 1 (b)).

これらの正極板１０Ｘ及び１０Ｙは次のようにして作製した。まず、コバルト酸リチウム（ＬｉＣｏＯ２）からなる正極活物質をアセチレンブラック、グラファイト等の炭素系導電剤（例えば５質量％）と、ポリビニリデンフルオライド（ＰＶｄＦ）よりなる結着剤（例えば３質量％）等を、Ｎ−メチルピロリドンからなる有機溶剤等に溶解したものを混合して、活物質合剤スラリーあるいは活物質合剤ペーストとした。これらの活物質合剤スラリーあるいは活物質合剤ペーストを、スラリーの場合はダイコーター、ドクターブレード等を用いて、ペーストの場合はローラコーティング法等により正極芯体（例えば、厚みが１５μｍのアルミニウム箔あるいはアルミニウムメッシュ）１１の両面に均一に塗付して活物質合剤１２を塗布した正極板を形成した。この後、活物質合剤を塗布した正極板を乾燥機中に通過させて、スラリーあるいはペースト作製時に必要であった有機溶剤を除去して乾燥させ、乾燥後にこの正極板をロールプレス機により圧延して、厚みが０．１８ｍｍ、幅５８０ｍｍ、長さ７００ｍｍの正極板の原材１５を２枚作製した。 These positive plates 10X and 10Y were produced as follows. First, a positive electrode active material made of lithium cobaltate (LiCoO 2 ) is made of a carbon-based conductive agent (eg, 5% by mass) such as acetylene black and graphite, and a binder (eg, 3% by mass) of polyvinylidene fluoride (PVdF). ) And the like dissolved in an organic solvent composed of N-methylpyrrolidone or the like was mixed to obtain an active material mixture slurry or an active material mixture paste. These active material mixture slurries or active material mixture pastes are used in the case of a slurry by using a die coater, a doctor blade or the like. (Alternatively, an aluminum mesh) 11 was applied uniformly on both surfaces of the positive electrode plate with the active material mixture 12 applied thereto. Thereafter, the positive electrode plate coated with the active material mixture is passed through a dryer to remove the organic solvent necessary for slurry or paste preparation and dried. After drying, the positive electrode plate is rolled by a roll press. Then, two raw materials 15 for the positive electrode plate having a thickness of 0.18 mm, a width of 580 mm, and a length of 700 mm were produced.

次に、図２のテープ貼付治具２０を使用した熱溶着性テープの電極板への貼付工程を図３を用いて説明する。このテープ貼付治具２０は、アルミニウム等の熱伝導性の良好な金属製本体２１及び可動式テープカット刃２２とからなる。金属製本体２１は、底面２３は平らな表面を有しており、底面２３から上部に向けて内部を貫通する複数個の吸引孔２４を備えている。そして、金属製本体２１は、内部にヒータ（図示せず）を備え、常時底面２３が所定温度（例えば１００℃）に加熱制御されるようになっている。さらに複数個の吸引孔２４は図示しない吸引手段に接続されて内部に負圧が与えられ、金属製本体２１が吸着ヘッドを構成するようになっている。また、可動式テープカット刃２２は、金属製本体２１の一側面に上下動可能に取り付けられており、図示しない制御手段により制御されて金属製本体２１の底面２３に吸着されている熱溶着性テープを所定の長さに切断するようになっている。このテープ用治具２０は、周知の位置決め手段（図示せず）により、テープ吸着切断位置とテープ貼付位置との間の移動を制御されている。   Next, the process of applying the heat-welding tape to the electrode plate using the tape application jig 20 of FIG. 2 will be described with reference to FIG. The tape sticking jig 20 is composed of a metal main body 21 having a good thermal conductivity such as aluminum and a movable tape cutting blade 22. The metal main body 21 has a flat bottom surface 23 and a plurality of suction holes 24 penetrating the inside from the bottom surface 23 toward the top. The metal main body 21 includes a heater (not shown) inside, and the bottom surface 23 is constantly controlled to be heated to a predetermined temperature (for example, 100 ° C.). Further, the plurality of suction holes 24 are connected to suction means (not shown) so that a negative pressure is applied to the inside, and the metal main body 21 constitutes a suction head. The movable tape cutting blade 22 is attached to one side surface of the metal main body 21 so as to be movable up and down, and is thermally welded by being controlled by a control means (not shown) and adsorbed on the bottom surface 23 of the metal main body 21. The tape is cut to a predetermined length. The movement of the tape jig 20 between the tape suction cutting position and the tape application position is controlled by a known positioning means (not shown).

まず、熱溶着性テープコイル３１より、貼付面に糊材としてエチレン−エチルアクリレート層を付着した厚み３０μｍのポリプロピレンテープからなる熱溶着性テープ３２を切断穴３３を有する基台３４の表面のテープ切断位置へ配置する。このテープ切断位置で、テープ貼付治具２０を熱溶着性テープ３２の先端部に配置し、最初に金属製本体２１を作動させることにより熱溶着性テープ３２を金属製本体２１と切断台３３との間に固定し、次いでテープカット刃３３を駆動することにより幅６００ｍｍ、長さ９ｍｍに切断するとともに復数個の吸引孔２４を負圧にすることにより切断された熱溶着性テープが金属製本体２１の底面２３に吸着された状態となるようにされている。   First, from the heat-welding tape coil 31, the surface of the base 34 having a cutting hole 33 is cut from a heat-welding tape 32 made of a polypropylene tape having a thickness of 30 μm with an ethylene-ethyl acrylate layer attached as an adhesive to the pasting surface. Place to position. At this tape cutting position, the tape adhering jig 20 is disposed at the tip of the heat-welding tape 32, and the metal main body 21 is first operated to attach the heat-welding tape 32 to the metal main body 21 and the cutting table 33. Next, by driving the tape cutting blade 33, the tape is cut into a width of 600 mm and a length of 9 mm, and the heat-sealable tape that has been cut by applying negative pressure to the multiple suction holes 24 is made of metal. The main body 21 is attracted to the bottom surface 23.

その後、テープ貼付治具２０を図３（ｂ）に示すテープ貼付位置まで移動させ、基台３４上に載置されている正極板の原材１５の表面の活物質合剤１２の塗布部と未塗布部との境界付近に押圧するとともに吸引孔２４の負圧を解く。このときテープ貼付治具２０の金属製本体２１の底面２３は１００℃程度に加熱されているので、熱溶着性テープ３２の貼付面に糊材として設けられているエチレン−エチルアクリレート層が溶融し、熱溶着性テープ３２が正極板の表面の活物質合剤１２の塗布部と未塗布部との境界が完全に覆われるように貼り付けられる。   Thereafter, the tape sticking jig 20 is moved to the tape sticking position shown in FIG. 3B, and the application portion of the active material mixture 12 on the surface of the raw material 15 of the positive electrode plate placed on the base 34 is While pressing near the boundary with the uncoated portion, the negative pressure of the suction hole 24 is released. At this time, since the bottom surface 23 of the metal main body 21 of the tape application jig 20 is heated to about 100 ° C., the ethylene-ethyl acrylate layer provided as a paste material on the application surface of the heat welding tape 32 is melted. The heat-weldable tape 32 is affixed so that the boundary between the application part and the non-application part of the active material mixture 12 on the surface of the positive electrode plate is completely covered.

このとき、実施例としては、図４（ａ）に示すように、熱溶着性テープ３２のポリプロピレンテープの易収縮軸方向が電極板の長さ方向になるように貼り付け、比較例としては、図４（ｂ）に示すように、易収縮軸方向が電極板の幅方向になるように貼り付けた。その後、図４（ａ）及び図４（ｂ）に示されているように、正極板の原材１５の幅方向に対して垂直にスリットし、それぞれ図１（ａ）及び図１（ｂ）に示すような１０枚の幅５５．５ｍｍ、長さ７００ｍｍの短冊状の電極板１０Ｘ及び１０Ｙを得た。   At this time, as an example, as shown in FIG. 4 (a), the heat-weldable tape 32 is attached so that the easy contraction axis direction of the polypropylene tape is the length direction of the electrode plate, As shown in FIG.4 (b), it affixed so that the easy contraction axis direction might turn into the width direction of an electrode plate. Thereafter, as shown in FIGS. 4 (a) and 4 (b), slitting is performed perpendicularly to the width direction of the raw material 15 of the positive electrode plate, respectively, and FIGS. 1 (a) and 1 (b) respectively. 10 strip-shaped electrode plates 10X and 10Y having a width of 55.5 mm and a length of 700 mm were obtained.

<熱収縮の測定>
得られたそれぞれ１０枚の実施例の正極板１０Ｘ及び比較例の正極板１０Ｙを、前述の境界部が完全にテープで覆われていることを確認した後に、１００℃の恒温槽の中に２時間放置して熱処理を施した。その後、それぞれの正極板１０Ｘ及び１０Ｙに貼付されているテープの電極板の幅方向の収縮長さを測定し、表１にまとめた。なお、表１中、Ｘ１〜Ｘ１０は実施例の正極板１０Ｘの１０枚のそれぞれのサンプル番号を示し、同じくＹ１〜Ｙ１０は比較例の正極板１０Ｙの１０枚のそれぞれのサンプル番号を示す。 <Measurement of heat shrinkage>
After confirming that the above-mentioned boundary part was completely covered with the tape, the positive electrode plate 10X of each of the ten examples and the positive electrode plate 10Y of the comparative example obtained were each placed in a thermostatic chamber at 100 ° C. Heat treatment was carried out by standing for a period of time. Then, the contraction length of the width direction of the electrode plate of the tape affixed to each positive electrode plate 10X and 10Y was measured, and it summarized in Table 1. In Table 1, X1 to X10 indicate 10 sample numbers of the positive electrode plate 10X of the example, and similarly Y1 to Y10 indicate 10 sample numbers of the positive electrode plate 10Y of the comparative example.

Figure 0004518850
Figure 0004518850

この表１に示した結果から以下のことがわかる。即ち、１００℃２時間の熱処理を行うことによって、ポリプロピレンテープの易収縮軸が電極板の幅方向となる比較例の正極板１０Ｙではテープの電極板の幅方向の長さが平均０．８７ｍｍ収縮することが判明した。一方、ポリプロピレンテープの易収縮軸方向が電極板の長さ方向となる実施例の正極板１０Ｘでは、テープの電極板の幅方向の長さが平均０．２３ｍｍしか収縮せず、活物質合剤塗布部と未塗布部との境界部の露出が抑えられたと言える。   From the results shown in Table 1, the following can be understood. That is, by performing heat treatment at 100 ° C. for 2 hours, in the positive electrode plate 10Y of the comparative example in which the easy contraction axis of the polypropylene tape is in the width direction of the electrode plate, the length in the width direction of the electrode plate of the tape shrinks by an average of 0.87 mm. Turned out to be. On the other hand, in the positive electrode plate 10X of the example in which the easy contraction axis direction of the polypropylene tape is the length direction of the electrode plate, the length in the width direction of the electrode plate of the tape contracts only 0.23 mm on average, and the active material mixture It can be said that the exposure of the boundary part between the application part and the non-application part was suppressed.

以上より、絶縁性テープを易収縮軸方向が電極板の長さ方向になるように貼り付けることによって、テープの貼付後に電極板に熱が加えられテープが収縮した場合でも、テープを易収縮軸方向が電極板の幅方向になるように貼り付けた時と比べ、前述の境界部の露出を抑えることができる。   As described above, even if the tape is contracted by applying heat to the electrode plate after applying the tape, the insulating tape is attached so that the direction of the easy contraction axis is the length direction of the electrode plate. Compared with the case where the direction is the width direction of the electrode plate, it is possible to suppress the exposure of the boundary portion.

なお、本実施例では、二次電池用電極を熱処理した場合の作用・効果を確認した例のみを示したが、この二次電池用電極を常法に従って対となる他の電極板とセパレータを介して渦巻状に巻回された渦巻状電極群を作製し、この渦巻型電極群を周知の外装体内に封入して二次電池を作製すれば、前記絶縁性テープの幅方向の熱収縮が小さくなることから、得られた二次電池の内部短絡が減少することは当業者にとり自明であろう。   In this example, only the example of confirming the action / effect when the electrode for the secondary battery is heat-treated is shown, but the electrode for the secondary battery is separated from the other electrode plate and separator which are paired according to a conventional method. If a spiral electrode group wound in a spiral shape is produced, and this spiral electrode group is enclosed in a well-known exterior body to produce a secondary battery, the heat shrinkage in the width direction of the insulating tape is reduced. It will be apparent to those skilled in the art that the internal battery short-circuit of the obtained secondary battery is reduced because it becomes smaller.

図１（ａ）は実施例に対応する正極板の平面図であり、図１（ｂ）は比較例に対応する正極板の平面図である。FIG. 1A is a plan view of a positive electrode plate corresponding to the example, and FIG. 1B is a plan view of a positive electrode plate corresponding to the comparative example. テープ貼付治具の斜視図である。It is a perspective view of a tape sticking jig. 図３（ａ）はテープ切断位置での動作を説明する図であり、図３（ｂ）はテープ貼付位置での動作を説明する図である。FIG. 3A is a diagram for explaining the operation at the tape cutting position, and FIG. 3B is a diagram for explaining the operation at the tape applying position. 正極板の原材の活物質合剤塗布部と未塗布部との境界部を絶縁性テープで被覆した場合の易収縮軸の関係を示す図であり、図４（ａ）は実施例、図４（ｂ）は比較例の場合を示す。It is a figure which shows the relationship of the easy contraction axis | shaft at the time of coat | covering the boundary part of the active material mixture application | coating part of a raw material of a positive electrode plate with an insulating tape, and Fig.4 (a) is an Example, figure 4 (b) shows the case of the comparative example. 従来の非水電解質二次電池の渦巻状電極群の構成を示す図である。It is a figure which shows the structure of the spiral electrode group of the conventional nonaqueous electrolyte secondary battery. 先願発明で使用されている一方の電極板を示す図であり、図６（ａ）は一方の電極板の長さ方向の横断面図であり、図６（ｂ）は平面図である。It is a figure which shows one electrode plate currently used by prior invention, FIG. 6 (a) is a cross-sectional view of the length direction of one electrode plate, FIG.6 (b) is a top view. 電極板に貼付された絶縁性テープの熱収縮方向を説明するための図である。It is a figure for demonstrating the heat shrink direction of the insulating tape affixed on the electrode plate.

符号の説明Explanation of symbols

１０ 正極板
１０Ｘ 実施例に対応する正極板
１０Ｙ 比較例に対応する正極板
１１ 正極芯体
１２ 正極活物質合剤
１３Ｘ 実施例に対応する熱溶着性テープ
１３Ｙ 比較例に対応する熱溶着性テープ
１５ 正極板の原材
２０ テープ貼付治具
２１ 金属製本体
２２ 可動式テープカット刃
２３ 底面
２４ 吸引孔
３１ 溶着性テープコイル
３２ 熱溶着性テープ
３３ 切断穴
３４ 基台 DESCRIPTION OF SYMBOLS 10 Positive electrode plate 10X Positive electrode plate 10Y corresponding to an Example Positive electrode plate 11 corresponding to a comparative example 11 Positive electrode core body 12 Positive electrode active material mixture 13X Thermal welding tape 13Y corresponding to an example Thermal weldable tape 15 corresponding to a comparative example Raw material of positive electrode plate 20 Tape attaching jig 21 Metal main body 22 Movable tape cutting blade 23 Bottom surface 24 Suction hole 31 Weldable tape coil 32 Thermal weldable tape 33 Cutting hole 34 Base

Claims (6)

電極板の活物質合剤塗布部と未塗布部との境界部が絶縁性テープで被覆されており、かつその絶縁性テープの易収縮軸方向が電極板の長さ方向である二次電池用電極板。   For secondary batteries in which the boundary between the active material mixture coated portion and uncoated portion of the electrode plate is covered with an insulating tape, and the easy contraction axis direction of the insulating tape is the length direction of the electrode plate Electrode plate. 前記絶縁性テープは、その一面に低温熱可塑性糊材が付着されており、前記電極板の活物質合剤塗布部と未塗布部との境界部に熱溶着されていることを特徴とする請求項１記載の二次電池用電極板。   The insulating tape has a low-temperature thermoplastic glue material attached to one surface thereof, and is thermally welded to a boundary portion between the active material mixture coated portion and the uncoated portion of the electrode plate. Item 2. The electrode plate for a secondary battery according to Item 1. 前記請求項１又は２に記載の二次電池用電極板が対となる他の電極板とセパレータを介して渦巻状に巻回された渦巻状電極群を有し、前記渦巻状電極群が外装体内に封入されていることを特徴とする二次電池。   The electrode plate for a secondary battery according to claim 1 or 2 has a spiral electrode group wound in a spiral shape with another electrode plate paired with a separator, and the spiral electrode group is an exterior A secondary battery characterized by being enclosed in a body. 次の（１）〜（４）の各工程を含む二次電池用電極板の製造方法。
（１）所定の電極板の幅よりも広い導電性芯体の少なくとも一方の表面に、前記所定の電極板の幅より広くかつ所定の長さに亘って活物質合剤を塗布する工程、
（２）一面に糊材が付着された絶縁性テープから、電極板の所定の幅長より広い絶縁性テープを得る工程、
（３）前記電極板の活物質合剤塗布部と未塗布部との境界部を覆い、前記絶縁性テープの易収縮軸方向が前記電極板の長さ方向となるように、前記絶縁性テープを貼付する工程、
（４）次いで、前記電極板と前記絶縁性テープとを同時に切断して、復数の所定の電極板を形成する工程。 The manufacturing method of the electrode plate for secondary batteries including each process of following (1)-(4).
(1) A step of applying an active material mixture over a predetermined length that is wider than the predetermined electrode plate, on at least one surface of the conductive core wider than the predetermined electrode plate;
(2) A step of obtaining an insulating tape wider than a predetermined width of the electrode plate from an insulating tape having a glue material attached to one surface;
(3) The insulating tape covers a boundary portion between the active material mixture application portion and the non-application portion of the electrode plate, and the easy contraction axis direction of the insulating tape is the length direction of the electrode plate. A process of applying,
(4) Next, the step of simultaneously cutting the electrode plate and the insulating tape to form a predetermined number of electrode plates. 前記糊材は低温熱可塑性の糊材であって、前記（３）の工程における絶縁性テープを貼付する工程を熱溶着法により行うことを特徴とする請求項４記載の二次電池用電極板の製造方法。   5. The electrode plate for a secondary battery according to claim 4, wherein the paste material is a low-temperature thermoplastic paste material, and the step of applying the insulating tape in the step (3) is performed by a heat welding method. Manufacturing method. 前記（２）及び（３）の工程を、加熱手段を備えるとともに吸着ヘッドを兼ねている金属製本体と、前記金属製本体に取り付けられた可動式テープカット刃とを備えたテープ貼付治具を用いて行うことを特徴とする請求項４に記載の二次電池用電極板の製造方法。   A tape sticking jig provided with a metal main body having heating means and also serving as a suction head, and a movable tape cutting blade attached to the metal main body in the steps (2) and (3). The method for producing an electrode plate for a secondary battery according to claim 4, wherein
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