JP2006155908A

JP2006155908A - Flat battery

Info

Publication number: JP2006155908A
Application number: JP2004340123A
Authority: JP
Inventors: Keiichiro Uenae; 圭一郎植苗; Jun Sato; 佐藤　　淳
Original assignee: Hitachi Maxell Ltd
Current assignee: Maxell Holdings Ltd
Priority date: 2004-11-25
Filing date: 2004-11-25
Publication date: 2006-06-15

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat battery which can be sealed excellently even if a heating temperature at the sealing of an inner container and an outer container is made low or a heating time is shortened, and in which superior leakage resistance can be secured, and the expansion of an inner volume and the weight reduction of the battery can be achieved. <P>SOLUTION: The battery 10 has a power generation element sealed in the outer package in which the inner container 11 and the outer container 12 are insertion-engaged at respective side walls. The insertion engagement part of the inner container and the outer container is sealed by heat-sealing an adhesive layer 13 laminating two or more resin layers 13a, 13b having as adhesive components resins different in melting temperatures to the inner container and the outer container. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、内容積の拡大や軽量化を達成できると共に、耐漏液性にも優れた扁平形電池に関するものである。 The present invention relates to a flat battery that can achieve an increase in internal volume and weight reduction, and is excellent in leakage resistance.

近年、ブルーツースなどの無線技術の進歩やＩＣの高集積化などによって、小型携帯機器（小型モバイル機器）の多様化が進んでおり、その一方でこれらの機器に適応できる電池が要求されている。こうした電池に要求される主な特性としては、容量が大きいこと、軽いこと、更には機器が人体に接触した状態で使用されることから、信頼性が高いことが挙げられる。 In recent years, due to advances in wireless technology such as Bluetooth and higher integration of ICs, diversification of small portable devices (small mobile devices) has progressed, while batteries that can be adapted to these devices are required. The main characteristics required for such a battery include high capacity, light weight, and high reliability because the device is used in contact with the human body.

現在、こうした用途には、コイン形電池（ボタン形電池）やラミネート型電池が主に用いられているが、これらの電池の特性は、上記の各要求特性の高まりに十分に追随できているとはいい難く、特に容量については、要求レベルと現実のレベルの差が大きくなっている。例えば、携帯機器の電源として主に用いられているリチウムイオン二次電池では、電極材料などの改良によって高容量化が図られてきたが、こうした改良方法による特性向上もほぼ飽和しつつある。 At present, coin-type batteries (button-type batteries) and laminate-type batteries are mainly used for such applications, but the characteristics of these batteries can sufficiently follow the above-mentioned increases in required characteristics. In particular, regarding the capacity, the difference between the required level and the actual level is large. For example, in a lithium ion secondary battery mainly used as a power source for portable devices, the capacity has been increased by improving electrode materials and the like, but the improvement in characteristics by such an improved method is almost saturated.

従来のコイン形電池の断面概略図を図５に示す。図５中、２０は電池、２１は内側容器（負極缶）、２２は外側容器（正極缶）、２３はガスケット、２４は負極、２５はセパレータ、２６は正極である。また、電池２０内部には、電解液（図示しない）が注入されている。図５に示すように、コイン形電池２０では、電池の外装体を構成することになる内側容器２１と外側容器２２とを、成形体であるガスケット２３を介してかしめ封口しており、気密性が高く、かつ機械的強度に優れている。しかしながら、これらのコイン形電池では、図５に示すように、ガスケット２３を使用する関係上、内側容器２１と外側容器２２との嵌合部の占める体積が大きく、また、ガスケット２３のように、封止に用いる材料の量も多いため、これらを含めた封止部（外側容器２２側壁の外周部と、ガスケット２３の内周面とで仕切られた領域、すなわち図５中の２本の点線で仕切られた領域Ａ’）の占める割合は大きなものとなり、電池の内容積の拡大、さらに電池の軽量化に当たっては、大きな制約があった。すなわち、優れた封止性能を確保するためには、封止部の幅（図５の２本の点線の間の距離）をおよそ１ｍｍ以上とする必要があり、径方向での電池の断面積：Ｓ（ｍｍ^２）に対する封止部の断面積の割合：Ｔ（％）は、電池径が２５ｍｍのときには約１５％、１５ｍｍの時には約２５％、５ｍｍのときには約６４％と、電池径が小さくなるほど電池内容積のロスが大きくなっていた。 A schematic cross-sectional view of a conventional coin-type battery is shown in FIG. In FIG. 5, 20 is a battery, 21 is an inner container (negative electrode can), 22 is an outer container (positive electrode can), 23 is a gasket, 24 is a negative electrode, 25 is a separator, and 26 is a positive electrode. In addition, an electrolytic solution (not shown) is injected into the battery 20. As shown in FIG. 5, in the coin-type battery 20, the inner container 21 and the outer container 22 that constitute the battery outer body are caulked and sealed through a gasket 23 that is a molded body, so that airtightness is achieved. And high mechanical strength. However, in these coin-type batteries, as shown in FIG. 5, the volume occupied by the fitting portion between the inner container 21 and the outer container 22 is large due to the use of the gasket 23. Since the amount of the material used for sealing is also large, the sealing portion including these (the region partitioned by the outer peripheral portion of the side wall of the outer container 22 and the inner peripheral surface of the gasket 23, that is, the two dotted lines in FIG. The area occupied by the area A ′) partitioned by is large, and there are significant restrictions in expanding the internal volume of the battery and reducing the weight of the battery. That is, in order to ensure excellent sealing performance, the width of the sealing portion (the distance between the two dotted lines in FIG. 5) needs to be approximately 1 mm or more, and the cross-sectional area of the battery in the radial direction : Ratio of the cross-sectional area of the sealing portion to S (mm ² ): T (%) is about 15% when the battery diameter is 25 mm, about 25% when the battery diameter is 15 mm, and about 64% when the battery diameter is 5 mm. The smaller the battery capacity, the greater the battery capacity loss.

他方、内側容器と外側容器との嵌合部の封口を、ガスケットを用いたかしめによらず、接着剤で行った電池も提案されている（特許文献１〜２）。これらの技術によれば、封止部が占める部分の体積を抑えて、電池内容積を大きくできる可能性がある。 On the other hand, a battery has been proposed in which the fitting portion between the inner container and the outer container is sealed with an adhesive regardless of caulking using a gasket (Patent Documents 1 and 2). According to these techniques, there is a possibility that the internal volume of the battery can be increased by suppressing the volume of the portion occupied by the sealing portion.

特開昭５５−１１１０６０号公報JP 55-1111060 A 実開昭５８−１３９６６８号公報Japanese Utility Model Publication No. 58-139668

しかしながら、上記特許文献１〜２に係る電池では、主として接着剤の接着能力により電池の封止性能が決定されるが、これは、例えば接着面積などに依存するため、電池の高さを低くして電池を薄型化しようとした場合には、接着面積が小さくなって接着能力が低下し、ガスケットを用いる電池に比べて気密性が劣り、電解液の漏れ抑制が不十分となることもあった。 However, in the batteries according to Patent Documents 1 and 2, the sealing performance of the battery is determined mainly by the adhesive ability of the adhesive. This depends on, for example, the adhesion area, and thus the height of the battery is reduced. When trying to reduce the thickness of the battery, the bonding area is reduced, the bonding ability is lowered, the airtightness is inferior to the battery using the gasket, and the electrolyte leakage control may be insufficient. .

本発明者らは、特定形状の内側容器および外側容器を使用すると共に、これら内側容器と外側容器の嵌合部を接着層により封止することで、上記特許文献１〜２に係る電池の抱える問題点を解決して、ガスケットを用いてかしめ封口した電池と同等レベルの耐漏液性を確保しつつ、内容積の拡大や軽量化を達成し得る扁平形電池と、該電池の製造方法を開発した。かかる扁平形電池では、内側容器と外側容器の嵌合部を封止するに当たり、接着層を内側容器および外側容器に熱融着させることが推奨される。 The present inventors use a specific shape of the inner container and the outer container, and seal the fitting portion between the inner container and the outer container with an adhesive layer, thereby holding the battery according to Patent Documents 1 and 2 above. Developed a flat battery that can solve the problem and achieve an increase in internal volume and weight while securing the same level of leakage resistance as that of a battery that is caulked and sealed with a gasket, and a method for manufacturing the battery. did. In such a flat battery, it is recommended that the adhesive layer be heat-sealed to the inner container and the outer container when the fitting portion between the inner container and the outer container is sealed.

本発明は、このような扁平形電池を更に改良して、内側容器と外側容器の封止の際に与える加熱温度を低くしたり加熱時間を短くしても、良好に封止でき優れた耐漏液性を確保できると共に、電池内容積の拡大や電池の軽量化も達成可能な扁平形電池を提供することを課題とする。 The present invention further improves such a flat battery so that it can be sealed well even when the heating temperature applied when sealing the inner container and the outer container is lowered or the heating time is shortened. It is an object of the present invention to provide a flat battery capable of ensuring liquidity and capable of increasing the battery internal volume and reducing the weight of the battery.

本発明は、内側容器と外側容器とを、それぞれの側壁で嵌合してなる外装体内部に発電要素を封入した扁平形電池について、上記内側容器と上記外側容器との嵌合部を封止するに当たり、互いに融着温度の異なる樹脂を接着成分として有する２以上の樹脂層を積層してなる接着層を、上記外側容器および上記内側容器に熱融着させることで、上記課題を解決したものである。 The present invention seals a fitting portion between the inner container and the outer container for a flat battery in which a power generation element is sealed inside an outer package formed by fitting an inner container and an outer container with respective side walls. In doing so, an adhesive layer formed by laminating two or more resin layers each having a resin having a different fusion temperature as an adhesive component is heat-sealed to the outer container and the inner container, thereby solving the above problems. It is.

すなわち、内側容器と外側容器との嵌合部を、内側容器および外側容器に接着層を熱融着させて封止する場合には、一方から（すなわち、外側容器の外側から）加熱することとなるため、外側容器と接着層との融着と、内側容器と接着層との融着とでは、これらの厚みに起因して融着時の条件（温度）が異なってしまう。接着層は、その温度が、接着成分である樹脂の融点を超えると融着が進み接着強度が高くなり始め、以後温度が上がるにつれて接着強度も高めることができ、ある程度の温度で強度は飽和する。仮に、接着層を単一の層とした場合、融着温度を、外側容器と接着層との熱融着が良好となるような（すなわち、接着強度が十分に確保できるような）温度にしても、内側容器と接着層との熱融着の場合には温度が低いままで、十分な融着が達成できないことがある。他方、内側容器と接着層との熱融着が良好となるような温度条件とした場合には、外側容器側では、接着層の温度が高くなりすぎて接着層の流れが生じ、内側容器−外側容器間の絶縁が不十分となって短絡を引き起こすことがある。また、融着温度はあまり高めずに融着時間を長くすることで、内側容器と接着層との熱融着を達成しようとすると、電池内部に装填した発電要素が熱の影響を受けて、電池特性の低下を引き起こすこともある。このようなことから、接着層が単一の樹脂層の場合には、融着の際の温度や時間を厳密に調整する必要があった。 That is, when the fitting portion between the inner container and the outer container is sealed by thermally fusing the adhesive layer to the inner container and the outer container, heating from one side (that is, from the outside of the outer container) Therefore, the fusion condition between the outer container and the adhesive layer and the fusion between the inner container and the adhesive layer are different from each other in terms of the conditions (temperature) at the time of fusion. When the temperature of the adhesive layer exceeds the melting point of the resin as the adhesive component, the fusion proceeds and the adhesive strength starts to increase, and thereafter the adhesive strength can be increased as the temperature increases, and the strength is saturated at a certain temperature. . If the adhesive layer is a single layer, the fusing temperature is set to a temperature at which the thermal fusion between the outer container and the adhesive layer is good (that is, sufficient adhesive strength can be secured). However, in the case of thermal fusion between the inner container and the adhesive layer, the temperature remains low and sufficient fusion may not be achieved. On the other hand, when the temperature condition is such that the thermal fusion between the inner container and the adhesive layer is good, the temperature of the adhesive layer becomes too high on the outer container side, causing the flow of the adhesive layer, and the inner container- Insufficient insulation between the outer containers may cause a short circuit. In addition, by trying to achieve heat fusion between the inner container and the adhesive layer by increasing the fusion time without raising the fusion temperature so much, the power generation element loaded inside the battery is affected by heat, It may cause deterioration of battery characteristics. For this reason, when the adhesive layer is a single resin layer, it has been necessary to strictly adjust the temperature and time during fusion.

本発明では、接着層を、互いに融着温度の異なる樹脂を接着成分として有する２以上の樹脂層を積層した構成とすることで、外側容器と接着層との好適融着温度と、内側容器と接着層との好適融着温度とを変えることができる。よって、接着層を内側容器および外側容器に熱融着させる際の条件として、外側容器と接着層との融着が良好になり、かつ内側容器−外側容器間の絶縁が損なわれないように接着層の樹脂流れを抑制できるような温度とし、融着時間を比較的短時間としても、内側容器と接着層についても良好に熱融着させて、十分な接着強度を確保することができる。 In the present invention, the adhesive layer has a structure in which two or more resin layers having resins having different fusion temperatures as adhesive components are laminated, so that a suitable fusion temperature between the outer container and the adhesive layer, the inner container, The preferred fusing temperature with the adhesive layer can be changed. Therefore, as a condition when the adhesive layer is heat-sealed to the inner container and the outer container, the outer container and the adhesive layer are bonded well so that the insulation between the inner container and the outer container is not impaired. Even if the temperature is such that the resin flow of the layer can be suppressed and the fusing time is relatively short, the inner container and the adhesive layer can also be thermally fused well to ensure sufficient adhesive strength.

このようなことから、上記接着層は、外側容器に接する樹脂層の有する樹脂の融解温度が、内側容器に接する樹脂層の有する樹脂の融解温度よりも高いことが望ましい。 For this reason, the adhesive layer desirably has a melting temperature of the resin in the resin layer in contact with the outer container higher than the melting temperature of the resin in the resin layer in contact with the inner container.

本発明の電池は、従来のガスケットを用いて封口した電池に比べて遜色ない耐漏液性を確保しつつ、封止部（内側容器の側壁内周面と外側容器の側壁外周面とで仕切られる領域）の占める割合を低減し、また、封止部に用いる材料を低減できるため、内容積を大きくして電池容量を向上させ、かつ電池の軽量化を図ることができる。また、接着層に単一の樹脂層を用いた場合に比べて、内側容器と外側容器との封止の際の融着温度を低くしたり、融着時間を短縮化しても、良好な耐漏液性が確保できるため、電池の生産性を高めることができる。 The battery of the present invention is partitioned by the sealing portion (the inner peripheral surface of the inner container side wall and the outer peripheral surface of the outer container side wall while ensuring liquid leakage resistance comparable to that of a battery sealed using a conventional gasket. The ratio of the area) can be reduced, and the material used for the sealing portion can be reduced. Therefore, the internal volume can be increased to improve the battery capacity and reduce the weight of the battery. Compared to the case where a single resin layer is used for the adhesive layer, even if the fusing temperature when sealing the inner container and the outer container is lowered or the fusing time is shortened, good leakage resistance is achieved. Since liquidity can be ensured, battery productivity can be increased.

以下、本発明を詳細に説明する。図１は、本発明の電池の一例の要部を示す断面概略図である。１０は電池、１１は内側容器、１２は外側容器、１３は接着層、１４は負極、１５はセパレータ、１６は正極、１７は絶縁体であり、電池内部には電解液（図示しない）が注入されている。また図１の電池１０に係る接着層１３は、２つの樹脂層１３ａ、１３ｂにより構成されている。図１中、Ａは封止部であり、内側容器１１の側壁の内周面と外側容器１２の側壁の外周面とで仕切られる領域である。 Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic cross-sectional view showing the main part of an example of the battery of the present invention. 10 is a battery, 11 is an inner container, 12 is an outer container, 13 is an adhesive layer, 14 is a negative electrode, 15 is a separator, 16 is a positive electrode, and 17 is an insulator. An electrolyte (not shown) is injected into the battery. Has been. Further, the adhesive layer 13 according to the battery 10 of FIG. 1 includes two resin layers 13a and 13b. In FIG. 1, A is a sealing portion, which is an area partitioned by the inner peripheral surface of the side wall of the inner container 11 and the outer peripheral surface of the side wall of the outer container 12.

内側容器および外側容器は、電池の外装体を構成するものである。その素材は特に限定されず、従来公知の電池に用いられているもの［例えば、ステンレス鋼、鉄（例えば冷間圧延鋼板、好ましくは表面にＮｉなどのメッキを施したもの）、銅−ステンレス鋼クラッド材、ステンレス鋼を母材とするアルミニウムクラッド材など］を採用すればよい。 The inner container and the outer container constitute a battery outer package. The material is not particularly limited, and those used in conventionally known batteries [for example, stainless steel, iron (for example, cold-rolled steel plate, preferably plated with Ni or the like on its surface), copper-stainless steel A clad material, an aluminum clad material using stainless steel as a base material, etc.] may be employed.

内側容器および外側容器は、電池の状態では、図１に示すように、これらの側壁が、内側容器の底面および外側容器の底面に対して略垂直であるが、互いに嵌合される前は、側壁が、開口部側から底面側に向かって窄まる形状（以下、「テーパ形状」という場合がある）のカップ状であることが好ましい。 In the state of the battery, the inner container and the outer container are substantially perpendicular to the bottom surface of the inner container and the bottom surface of the outer container as shown in FIG. It is preferable that the side wall has a cup shape that is narrowed from the opening side toward the bottom surface side (hereinafter sometimes referred to as “taper shape”).

内側容器として、上記のようなテーパ形状を有するカップ状容器を用い、電池とする際に側壁を底面に対して略垂直にすることで、内側容器の側壁には、外側容器側に向けて広がろうとする押圧力が生じる。この押圧力によって、内側容器の側壁が、外側容器の側壁に押し付けられる。こうした内側容器の側壁のバネのような働き（バネ効果）により、内側容器−外側容器間の密着性が向上するため、電池の気密性、すなわち耐漏液性を更に高めることができる。 The cup-shaped container having the tapered shape as described above is used as the inner container, and when the battery is made, the side wall is made substantially perpendicular to the bottom surface so that the side wall of the inner container is widened toward the outer container side. A pressing force is generated to try to peel off. By this pressing force, the side wall of the inner container is pressed against the side wall of the outer container. Due to the action (spring effect) of the side wall of the inner container, the adhesion between the inner container and the outer container is improved, so that the airtightness of the battery, that is, the leakage resistance can be further improved.

また、図２に、本発明の扁平形電池の他の例の要部を表す断面概略図を示す。図２の電池は、外側容器１２の開口部側が内側容器１１の方に傾斜していることを除き、図１の電池と同じ構成を有している。この図２の電池のように、外側容器１２の開口部側を内側容器１１側へ傾斜させ、内側容器１１の抜け止めがなされるようにすると、密着性が向上することから、より好ましい。 FIG. 2 is a schematic cross-sectional view showing the main part of another example of the flat battery of the present invention. The battery of FIG. 2 has the same configuration as the battery of FIG. 1 except that the opening side of the outer container 12 is inclined toward the inner container 11. Like the battery of FIG. 2, it is more preferable that the opening side of the outer container 12 is inclined toward the inner container 11 so that the inner container 11 is prevented from coming off because the adhesion is improved.

図３に好適な内側容器１１の要部の断面図を示すが、図３中θ_１、すなわち、底面に対する垂線と、側壁の最も長い直線部分とのなす内角（以下、「テーパ角」という場合がある。後記の外側容器についても同じ。）が、０．５°以上、より好ましくは１°以上であって、１０°以下、より好ましくは５°以下であることが望ましい。内側容器側壁のテーパ角をこのような範囲に制御することで、上記のバネ効果が一層顕著となる。すなわち、内側容器側壁のテーパ角が小さすぎると、電池とした際の上記押圧力が小さくなり、内側容器側壁の上記バネ効果、すなわち内側容器−外側容器間の密着性向上効果が不十分となることがある。また、内側容器側壁のテーパ角が大きすぎると、外側容器との嵌合時の作業性が低下するなど、電池製造の際の作業性が低下することがある。 FIG. 3 shows a cross-sectional view of a main part of the preferred inner container 11. In FIG. 3, θ ₁ , that is, an internal angle formed by a perpendicular to the bottom surface and the longest straight portion of the side wall (hereinafter referred to as “taper angle”). The same applies to the outer container described later.) Is preferably 0.5 ° or more, more preferably 1 ° or more, and 10 ° or less, more preferably 5 ° or less. By controlling the taper angle of the inner container side wall in such a range, the above-described spring effect becomes more remarkable. That is, when the taper angle of the inner container side wall is too small, the pressing force when the battery is formed becomes small, and the spring effect of the inner container side wall, that is, the effect of improving the adhesion between the inner container and the outer container becomes insufficient. Sometimes. Moreover, when the taper angle of the inner container side wall is too large, workability at the time of battery manufacture may be lowered, for example, workability at the time of fitting with the outer container is lowered.

また、外側容器に上記のようなテーパ形状を有するカップ状容器を用いることで、外側容器内に内側容器を嵌合する際の作業性が向上するため、電池の生産性を更に高めることができる。図４に好適な外側容器１２の要部の断面図を示すが、図４中θ_２、すなわち、底面に対する垂線と、側壁の最も長い直線部分とのなす角（テーパ角）が、１°以上、より好ましくは２°以上であって、２０°以下、より好ましくは１５°以下であることが望ましい。外側容器側壁のテーパ角をこのような範囲に制御することで、電池製造時の作業性向上効果が一層顕著となる。すなわち、外側容器側壁のテーパ角が小さすぎると、電池製造の際の作業性向上効果が十分に確保できないことがある。また、このような形状の容器を用いて電池を製造する際には、内側容器と外側容器を、接着層を介して嵌合させ、内側容器の側壁および外側容器の側壁が、内側容器の底面および外側容器の底面に対して略垂直となるように圧縮するが、外側容器側壁のテーパ角が大きすぎると、側壁の圧縮加工が困難になるなど、かえって作業性が低下することがある。 Moreover, since the workability | operativity at the time of fitting an inner container in an outer container improves by using the cup-shaped container which has the above taper shapes for an outer container, the productivity of a battery can be improved further. . FIG. 4 shows a cross-sectional view of the main part of the preferred outer container 12. In FIG. 4, θ ₂ , that is, the angle (taper angle) formed by the perpendicular to the bottom surface and the longest straight portion of the side wall is 1 ° or more. More preferably, it is 2 ° or more, 20 ° or less, and more preferably 15 ° or less. By controlling the taper angle of the outer container side wall in such a range, the workability improvement effect at the time of battery production becomes more remarkable. That is, if the taper angle of the outer container side wall is too small, the workability improvement effect during battery manufacturing may not be sufficiently ensured. Further, when manufacturing a battery using a container having such a shape, the inner container and the outer container are fitted via an adhesive layer, and the side wall of the inner container and the side wall of the outer container are the bottom surfaces of the inner container. In addition, the compression is performed so as to be substantially perpendicular to the bottom surface of the outer container. However, if the taper angle of the outer container side wall is too large, the workability may be deteriorated, for example, it may be difficult to compress the side wall.

内側容器底面および外側容器底面の形状としては、例えば、平面視で略円形や略楕円形、略四角形（略正方形や略長方形など）など、従来公知の一般的な扁平形電池（コイン形電池など）と同様の形状が挙げられるが、これらの形状に限定される訳ではない。また、内側容器および外側容器の大きさも特に制限はなく、例えば、従来公知の扁平形電池と同様の大きさとすることができ、更には、従来公知のものよりも大きくしたり小さくしたりすることもできる。具体的には、例えば、底面および上面が平面視で円形のコイン形電池でいえば、内側容器について、底面の直径：５〜３０ｍｍ、側壁の高さ（底面に対する垂直高さ、図３中ｈ_１）：１〜５ｍｍとすることが、また、外側容器について、底面の直径：５〜３０ｍｍ、側壁の高さ（底面に対する垂直高さ、図４中ｈ_２）：１〜５ｍｍとすることが一般的である。 The shapes of the bottom surface of the inner container and the bottom surface of the outer container include, for example, a generally known flat battery (coin-shaped battery, etc.) such as a substantially circular shape, a substantially oval shape, or a substantially square shape (such as a substantially square shape or a substantially rectangular shape) in plan view. ) And the like, but are not limited to these shapes. The size of the inner container and the outer container is not particularly limited. For example, the inner container and the outer container can be the same size as a conventionally known flat battery, and can be made larger or smaller than a conventionally known battery. You can also. Specifically, for example, in the case of a coin-shaped battery whose bottom and top surfaces are circular in plan view, the diameter of the bottom surface: 5 to 30 mm, the height of the side wall (the vertical height with respect to the bottom surface, h in FIG. ₁ ): 1 to 5 mm, and for the outer container, the bottom surface diameter: 5 to 30 mm, the side wall height (vertical height with respect to the bottom surface, h ₂ in FIG. 4): 1 to 5 mm. It is common.

なお、内側容器および外側容器の各底面形状が平面視で略四角形の電池の場合、四隅が曲線形状に仕上げられることが一般的であるが、本発明の電池に用いる内側容器および外側容器が上記のテーパ形状を有するカップ状容器の場合には、側壁が直線的な箇所で測定されるテーパ角（上記θ_１および上記θ_２）が、上記所定範囲内にあることが望ましい。 In addition, when each bottom shape of the inner container and the outer container is a substantially rectangular battery in plan view, the four corners are generally finished in a curved shape, but the inner container and the outer container used for the battery of the present invention are the above In the case of a cup-shaped container having a taper shape, it is desirable that the taper angles (the above θ ₁ and the above θ ₂ ) measured at a location where the side wall is linear are within the predetermined range.

本発明の電池では、内側容器と外側容器の嵌合部に、接着層を介在させて接着する。本発明の電池に係る接着層は、互いに融着温度が異なる樹脂を接着成分として有する２以上の樹脂層を積層してなるものである。接着層を構成する各樹脂層に適用できる樹脂としては、例えば、ポリエチレン、ポリプロピレン、エチレン−プロピレン共重合体などのポリオレフィン；ナイロン６、ナイロン６６、ナイロン１１、ナイロン１２、ナイロン６１０、ナイロン６１２、ナイロン６−ナイロン６６共重合体などの共重合ナイロンなどのポリアミド；熱可塑性ポリイミド；熱可塑性ポリアミドイミド；などが挙げられる。また、上記ポリオレフィンは、内側容器や外側容器を構成する金属との親和性が小さいことから、接着性を向上させる目的で、極性基（カルボキシル基や水酸基など）を導入した変性ポリオレフィンであってもよい。なお、後述するように、本発明の電池を製造する際に、接着層を内側容器および外側容器に熱融着させるときの温度は、外側容器に付加する温度を、１５０〜２３０℃とすることが望ましい。このため、上記合成樹脂の中でも、上記温度で熱融着可能なもの（すなわち、融着温度が上記範囲内にあるもの）が推奨される。 In the battery according to the present invention, the inner container and the outer container are bonded to each other with an adhesive layer interposed therebetween. The adhesive layer according to the battery of the present invention is formed by laminating two or more resin layers having resins having different fusion temperatures as adhesive components. Examples of the resin that can be applied to each resin layer constituting the adhesive layer include polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymer; nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon Polyamides such as nylon 6 copolymer such as 6-nylon 66 copolymer; thermoplastic polyimide; thermoplastic polyamideimide; In addition, the polyolefin is a modified polyolefin having a polar group (such as a carboxyl group or a hydroxyl group) introduced for the purpose of improving adhesiveness because of its low affinity with the metal constituting the inner and outer containers. Good. As will be described later, when the battery of the present invention is manufactured, the temperature when the adhesive layer is thermally fused to the inner container and the outer container is set to 150 to 230 ° C. Is desirable. For this reason, among the synthetic resins, those that can be heat-sealed at the above temperature (that is, those having a fusion temperature in the above range) are recommended.

なお、内側容器や外側容器と接着層との接着性が不十分な場合には、内側容器や外側容器の接着層との接着面を処理したり、接着層に使用する樹脂を処理するなどして、これらの接着性を高めることもできる。例えば、内側容器や外側容器の接着層との接着面を処理する方法としては、該接着面に、リン酸塩、クロム酸塩、フッ化物、トリアジンチオール化合物などの皮膜を形成する化成処理などが挙げられる。また、接着層に使用する樹脂の処理方法としては、例えば、該樹脂に無水マレイン酸などの不飽和基を有する酸などをグラフトさせる酸変性処理などが挙げられる。これら内側容器や外側容器の接着層との接着面の処理や、接着層に使用する樹脂の処理は、必要に応じていずれか一つを選択してもよく、両者を同時に実施しても構わない。 If the adhesiveness between the inner container or outer container and the adhesive layer is insufficient, the adhesive surface of the inner container or outer container with the adhesive layer is treated, or the resin used for the adhesive layer is treated. Thus, these adhesive properties can be enhanced. For example, as a method of treating the adhesion surface with the adhesive layer of the inner container or the outer container, there is a chemical conversion treatment for forming a film of phosphate, chromate, fluoride, triazine thiol compound, etc. on the adhesion surface. Can be mentioned. Examples of a method for treating the resin used for the adhesive layer include an acid modification treatment in which an acid having an unsaturated group such as maleic anhydride is grafted on the resin. Any one of the treatment of the adhesive surface with the adhesive layer of the inner container and the outer container and the treatment of the resin used for the adhesive layer may be selected as necessary, or both may be performed simultaneously. Absent.

また、本発明の電池では、例えば、外側容器の外側から加熱して熱融着を行うに当たり、例えば、一般的なポリエチレンやポリプロピレンの融着温度である１６０〜２００℃程度の温度を短時間（例えば、４秒以下）付加すると、接着層の厚みにもよるが、外側容器側と内側容器側の温度差は、大凡２０〜６０℃となる。よって、接着層を構成する各樹脂層のうち、最外層となる２つの層のうちの一方の層が有する樹脂の融着温度と、他方の層が有する樹脂の融着温度との差が、２０℃以上、より好ましくは３０℃以上であって、６０℃以下、更に好ましくは５０℃以下となるようにすることが望ましい。両外層が有する各樹脂の融着温度の差がこのような範囲となるようにし、より高い融着温度の樹脂を有する層を外側容器側に、より低い融着温度の樹脂を有する層を内側容器側に配することで、接着層と外側容器および内側容器とを、外側容器と接着層との融着に好適な温度で、かつ比較的短時間で、良好に熱融着させることができる。 Further, in the battery of the present invention, for example, when performing heat fusion by heating from the outside of the outer container, for example, a temperature of about 160 to 200 ° C., which is a fusion temperature of general polyethylene or polypropylene, is set for a short time ( (For example, 4 seconds or less), depending on the thickness of the adhesive layer, the temperature difference between the outer container side and the inner container side is approximately 20 to 60 ° C. Therefore, among the resin layers constituting the adhesive layer, the difference between the fusion temperature of the resin that one of the two outer layers becomes and the fusion temperature of the resin that the other layer has, It is desirable that the temperature be 20 ° C. or higher, more preferably 30 ° C. or higher, 60 ° C. or lower, more preferably 50 ° C. or lower. The difference between the fusing temperatures of the resins of both outer layers is within such a range, the layer having a resin having a higher fusing temperature is provided on the outer container side, and the layer having a resin having a lower fusing temperature is provided on the inner side. By arranging on the container side, the adhesive layer, the outer container, and the inner container can be heat-sealed well at a temperature suitable for fusion between the outer container and the adhesive layer and in a relatively short time. .

なお、本発明に係る上記接着層は、２つの樹脂層を有していればよいが、更に、３層以上（３層、４層、５層など）としてもよい。例えば、両外層に配すべき２つの樹脂層の密着性が、構成樹脂の特性上不十分となるような場合には、両外層との密着性が良好な他の樹脂層を間に設けた３層構成とすることができる。なお、上記接着層が３層以上の場合でも、外側容器に接する樹脂層の有する樹脂の融解温度が、内側容器に接する樹脂層の有する樹脂の融解温度よりも高くしておくことが好ましく、これらの間に存在する各樹脂層の樹脂については、その融解温度は、外側容器側および内側容器側の樹脂層に係る樹脂の融解温度よりも高くてもよく、低くても構わない。 The adhesive layer according to the present invention only needs to have two resin layers, but may further have three or more layers (three layers, four layers, five layers, etc.). For example, when the adhesion between two resin layers to be arranged on both outer layers is insufficient due to the characteristics of the constituent resin, another resin layer having good adhesion with both outer layers is provided between them. A three-layer structure can be adopted. Even when the number of the adhesive layers is three or more, it is preferable that the melting temperature of the resin in the resin layer in contact with the outer container is higher than the melting temperature of the resin in the resin layer in contact with the inner container. As for the resin of each resin layer existing between the two, the melting temperature may be higher or lower than the melting temperature of the resin related to the resin layer on the outer container side and the inner container side.

ここで、接着層を構成する各樹脂層が有する樹脂の融着温度は、ＪＩＳＫ７１２１の規定に準じて測定される融解温度で評価することができる。また、接着層を構成する各樹脂層には、上記の樹脂の他に、必要に応じて公知の各種添加剤が含まれていてもよい。 Here, the fusing temperature of the resin included in each resin layer constituting the adhesive layer can be evaluated by a melting temperature measured according to the provisions of JIS K7121. In addition to the above resins, various known additives may be contained in each resin layer constituting the adhesive layer as necessary.

接着層の厚みは、３０μｍ以上、より好ましくは５０μｍ以上であって、２００μｍ以下、より好ましくは１００μｍ以下とすることが望ましい。接着層の厚みが小さすぎると、内側容器−外側容器間の接着性や絶縁が不十分となることがある。他方、接着層の厚みをあまり大きくしても、内側容器−外側容器間の接着性や絶縁性が飽和するばかりか、接着に用いる材料（樹脂など）の量が増大するため、かえって電池の軽量化を阻害する要因になることがある。 The thickness of the adhesive layer is 30 μm or more, more preferably 50 μm or more, and is desirably 200 μm or less, more preferably 100 μm or less. If the thickness of the adhesive layer is too small, the adhesiveness and insulation between the inner container and the outer container may be insufficient. On the other hand, even if the thickness of the adhesive layer is too large, not only the adhesion and insulation between the inner container and the outer container are saturated, but the amount of material (resin etc.) used for adhesion increases, so the battery is lighter. It may become a factor that inhibits the conversion.

また、接着層を構成する各樹脂層の厚みは、特に制限はなく、接着層全体の厚みが上記の範囲内になるように調整し、かつ電池の気密性を十分に確保すべく外側容器および内側容器との密着性が良好なるように各層の厚みを適宜すればよい。特に電池では、電解液の漏液防止のみならず、外部の水分の電池内への浸入や電池内ガスの外部へのリークが好ましくない場合も多いため、これら水分の浸入やガスの外部リークが抑制できるように、構成する樹脂の特性に応じて各樹脂層の厚みを変化させることも推奨される。具体的には、各層の厚みを、例えば１０μｍ以上としつつ、接着層全体として、上記所定値となるように調整することが望ましい。 In addition, the thickness of each resin layer constituting the adhesive layer is not particularly limited, and is adjusted so that the thickness of the entire adhesive layer is within the above range, and the outer container and the battery to sufficiently ensure the airtightness of the battery. The thickness of each layer may be appropriately determined so that the adhesion with the inner container is good. In particular, in the battery, not only the leakage of the electrolyte solution but also the entry of external moisture into the battery and the leakage of gas inside the battery to the outside are often undesirable. It is also recommended to change the thickness of each resin layer in accordance with the characteristics of the resin to be configured so that it can be suppressed. Specifically, it is desirable to adjust the thickness of each layer to be the above-mentioned predetermined value as a whole while setting the thickness of each layer to 10 μm or more, for example.

なお、上記接着層は、外側容器および内側容器に熱融着させた後には、各樹脂層の界面近傍で構成樹脂同士がある程度混ざり合うことがあるため、界面は多少不明確になることがある。 In addition, after the above-mentioned adhesive layer is heat-sealed to the outer container and the inner container, the constituent resins may be mixed to some extent in the vicinity of the interface between the resin layers, so the interface may be somewhat unclear. .

本発明の扁平形電池に係る正極、負極、セパレータ、電解液などの各発電要素は特に制限されず、従来公知の一次電池や二次電池に採用されているものが適用できる。また、図１および図２に示す扁平形電池では、内側容器（負極缶）１１の側壁端部と外側容器（正極缶）１２と間に、絶縁板１７を配して内側容器１１−外側容器１２間の絶縁を図っているが、かかる絶縁板としても、従来公知の一次電池や二次電池に用いられているものが適用可能である。なお、図１および図２に示す扁平形電池では、内側容器１１側に負極１４が、外側容器１２側に正極１６が配されているが、本発明の扁平形電池では、内側容器側に正極が、外側容器側に負極が配された構造であってもよい。 The power generation elements such as the positive electrode, the negative electrode, the separator, and the electrolyte solution according to the flat battery of the present invention are not particularly limited, and those employed in conventionally known primary batteries and secondary batteries can be applied. Moreover, in the flat battery shown in FIG. 1 and FIG. 2, an insulating plate 17 is arranged between the side wall end of the inner container (negative electrode can) 11 and the outer container (positive electrode can) 12, and the inner container 11 -the outer container. Although insulation between 12 is aimed at, what is used for a conventionally well-known primary battery and secondary battery is applicable also as this insulating board. 1 and 2, the negative electrode 14 is disposed on the inner container 11 side and the positive electrode 16 is disposed on the outer container 12 side. However, in the flat battery of the present invention, the positive electrode is disposed on the inner container side. However, a structure in which the negative electrode is arranged on the outer container side may be used.

なお、本発明によれば、径方向での電池の断面積をＳ（ｍｍ^２）としたときに、径方向での電池の断面積に対する封止部の断面積の割合：Ｔ（％）が、およそ、
４０／（Ｓ）^１／２ ≦ Ｔ ≦ ２００／（Ｓ）^１／２
となる扁平形電池を構成することができる。外側容器または内側容器の厚みを低減するか、接着層の厚みを低減することにより、Ｔの値を上記範囲以下とすることは可能であるが、外側容器や内側容器の厚みを低減しすぎると、強度が低下して電池の変形などの問題が生じることがあり、また、接着層の厚みを低減しすぎると、短絡などの問題が生じることがあるため、Ｔの値は４０／（Ｓ）^１／２以上とすることが望ましく、５０／（Ｓ）^１／２以上とすることがより望ましい。他方、Ｔの値が大きくなるほど、電池の内容積が低下するため、Ｔの値は２００／（Ｓ）^１／２以下とすることが望ましい。 According to the present invention, when the cross-sectional area of the battery in the radial direction is S (mm ² ), the ratio of the cross-sectional area of the sealing portion to the cross-sectional area of the battery in the radial direction is T (%). ,about,
40 / (S) ^1/2 ≤ T ≤ 200 / (S) ^1/2
A flat battery can be configured. By reducing the thickness of the outer container or the inner container or by reducing the thickness of the adhesive layer, it is possible to make the value of T below the above range, but if the thickness of the outer container or the inner container is reduced too much The strength may decrease and problems such as battery deformation may occur, and if the thickness of the adhesive layer is excessively reduced, problems such as short circuits may occur, so the value of T is 40 / (S). it is desirable that a ^half or more, and more preferably set to 50 / ^{(S) 1/2} or more. On the other hand, as the value of T increases, the internal volume of the battery decreases. Therefore, the value of T is preferably 200 / (S) ^1/2 or less.

接着層について上記の好適厚みを採用し、汎用の容器厚みを採用した場合には、径方向での電池の断面積Ｓに対する封止部の断面積の割合Ｔは、電池径が２５ｍｍのときには約３〜５％、１５ｍｍのときには約６〜８％、５ｍｍのときには約１６〜２２％となり、ガスケットを用いた扁平形電池に比べて、封止部の断面積の割合Ｔを約１／３〜１／５に低減させることができる。 When the above preferred thickness is adopted for the adhesive layer and a general-purpose container thickness is adopted, the ratio T of the cross-sectional area of the sealing portion to the cross-sectional area S of the battery in the radial direction is approximately when the battery diameter is 25 mm. 3 to 5%, about 6 to 8% at 15 mm, and about 16 to 22% at 5 mm, and the ratio T of the cross-sectional area of the sealing portion is about 1/3 to that of a flat battery using a gasket. It can be reduced to 1/5.

次に、本発明の電池の製造方法を説明する。まず、内側容器の側壁外側、または外側容器の側壁内側に、接着層を構成するためのフィルム（接着成分である樹脂を含むフィルム）を貼り付ける。また、例えば、内側容器の側壁外側に融解温度の低い樹脂フィルムを、外側容器の側壁内側に融解温度の高い樹脂フィルムを貼り付けておき、熱融着時にこれらの樹脂フィルムを積層して接着層としてもよい。内側容器や外側容器への樹脂フィルムの貼り付けは、例えば、熱融着により行えばよいが、その他、仮止め接着剤を用いたり、接着層を構成するための合成樹脂や合成ゴムを含む薄肉のリング状成形体を作製して、これを内側容器の側壁外側に嵌める手法などを採用してもよい。 Next, a method for manufacturing the battery of the present invention will be described. First, a film for forming an adhesive layer (a film containing a resin as an adhesive component) is attached to the outer side wall of the inner container or the inner side wall of the outer container. Also, for example, a resin film having a low melting temperature is attached to the outside of the side wall of the inner container, and a resin film having a high melting temperature is attached to the inside of the side wall of the outer container, and these resin films are laminated at the time of heat-sealing to form an adhesive layer It is good. Affixing the resin film to the inner container or the outer container may be performed, for example, by heat sealing, but in addition, a thin-walled material including a temporary fixing adhesive or a synthetic resin or synthetic rubber for forming an adhesive layer A method may be employed in which a ring-shaped molded body is prepared and fitted to the outside of the side wall of the inner container.

次に、内側容器内に、例えば、図１に示すような構成で発電要素を装填する。電解液は、電池組み立て時にセパレータを所定位置に設置した後、該セパレータ上に注入することによって電池内部に導入することが一般的であるが、例えば、図１に示す電池であれば、内側容器１１に負極１４を圧着などさせた後、セパレータ１５を設置し、該セパレータ１５の正極１６側となる面に電解液を数滴垂らし、その後正極１６を設置し、該正極１６の外側容器１２側となる面に電解液を数滴垂らす方法などが採用できる。 Next, the power generation element is loaded into the inner container, for example, in a configuration as shown in FIG. The electrolytic solution is generally introduced into the battery by placing the separator at a predetermined position when the battery is assembled and then injecting the separator onto the separator. For example, in the case of the battery shown in FIG. After the negative electrode 14 is pressure-bonded to the separator 11, the separator 15 is installed, a few drops of the electrolyte is dropped on the surface of the separator 15 on the positive electrode 16 side, and then the positive electrode 16 is installed. For example, a method of dropping a few drops of electrolyte on the surface can be employed.

内側容器の端部の当接予定箇所に絶縁板を設置した外側容器を、発電要素を搭載した内側容器に被せ、外部容器外側から加熱することで接着層を内側容器および外側容器に熱融着させて、例えば、図１に示すような電池とする。熱融着の方法には特に制限はないが、例えば、加熱が要求される部分まで距離がある場合、効率的に短時間で加熱ができ、発電要素への伝熱を少なくして温度上昇を防ぐことが可能なことから、高周波を用いた誘導加熱が好適である。熱融着の際の温度（外側容器側へ付加する温度）は、例えば１５０〜２３０℃であることが好ましく、融着時間は、例えば１〜１０秒とすることが望ましい。温度が低すぎたり融着時間が短すぎると、融着が不十分となることがあり、温度が高すぎたり融着時間が長すぎると、発電要素に悪影響を及ぼすことがあるからである。 Cover the inner container with the power generation element on the outer container with an insulating plate at the planned contact point of the inner container end, and heat the outer container to heat-bond the adhesive layer to the inner and outer containers. For example, a battery as shown in FIG. 1 is obtained. There are no particular restrictions on the method of heat sealing, but for example, when there is a distance to the part where heating is required, heating can be performed efficiently in a short time, and heat transfer to the power generation element is reduced to increase the temperature. Induction heating using high frequency is preferable because it can be prevented. The temperature at the time of thermal fusion (temperature applied to the outer container side) is preferably 150 to 230 ° C., for example, and the fusion time is preferably 1 to 10 seconds, for example. This is because if the temperature is too low or the fusing time is too short, the fusing may be insufficient, and if the temperature is too high or the fusing time is too long, the power generation element may be adversely affected.

また、外側容器や内側容器に、図３や図４で示すようなテーパ形状のカップ状容器を用いた場合には、発電要素を装填した内側容器に外側容器を被せた後、外側容器の側壁が、外側容器底面に略垂直となるように圧縮（圧着）してから、接着層を熱融着させればよい。 When a tapered cup-shaped container as shown in FIG. 3 or FIG. 4 is used for the outer container or the inner container, the outer container is covered with the inner container loaded with the power generation element, and then the side wall of the outer container. However, after compression (crimping) so as to be substantially perpendicular to the bottom surface of the outer container, the adhesive layer may be heat-sealed.

以下、実施例に基づいて本発明を詳細に述べる。ただし、下記実施例は本発明を制限するものではなく、前・後記の趣旨を逸脱しない範囲で変更実施をすることは、全て本発明の技術的範囲に包含される。 Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

実施例１
図３に示す内側容器１１、および図４に示す外側容器１２を用いて、図１に示す構造の電池を作製した。内側容器１１は、厚みが０．２ｍｍのステンレス鋼製で、底面を円形とし、底面の直径を１９．３ｍｍ、開口端部の直径を１９．４ｍｍ、図３に示す高さｈ_１を１．９ｍｍ、テーパ角θ_１を１．５°とし、外側容器１２は、厚みが０．２ｍｍのステンレス鋼製で、底面を円形とし、底面の直径を１９．９ｍｍ、開口端部の直径を２０．２ｍｍ、図３に示す高さｈ_２を１．９ｍｍ、テーパ角θ_２を４．５°とした。 Example 1
A battery having the structure shown in FIG. 1 was produced using the inner container 11 shown in FIG. 3 and the outer container 12 shown in FIG. The inner container 11 is made of stainless steel having a thickness of 0.2 mm, has a circular bottom surface, a diameter of 19.3 mm at the bottom surface, a diameter of 19.4 mm at the open end, and a height h ₁ shown in FIG. 9 mm, and the taper angle theta ₁ 1.5 °, the outer container 12, the thickness was made 0.2mm stainless steel, and a bottom circular, 19.9 mm diameter of the bottom surface, the diameter of the open end 20. The height h ₂ shown in FIG. 3 was 1.9 mm, and the taper angle θ ₂ was 4.5 °.

正極１６は、次のようにして作製した。正極活物質としてＬｉＣｏＯ_２を、導電助剤としてカーボンブラック（三菱化学社製「ＣＢ３３５０Ｂ」）を用い、これらを質量比で８３：１０となるように混合した。バインダーとしてのポリフッ化ビニリデン（ＰＶＤＦ）が７質量％となるようにＮ−メチル−２−ピロリドンに溶解させた溶液をこの混合物に加え、撹拌して塗料とした。この塗料を一旦乾燥させて溶媒を除去した後、乳鉢で粉砕した。この粉砕物を金型に充填し加圧成形して直径が１８ｍｍ、厚みが０．９ｍｍのペレットとし、これを正極に用いた。 The positive electrode 16 was produced as follows. LiCoO ₂ was used as the positive electrode active material, and carbon black (“CB3350B” manufactured by Mitsubishi Chemical Corporation) was used as the conductive assistant, and these were mixed at a mass ratio of 83:10. A solution prepared by dissolving polyvinylidene fluoride (PVDF) as a binder in N-methyl-2-pyrrolidone so as to be 7% by mass was added to this mixture and stirred to obtain a paint. This paint was once dried to remove the solvent, and then pulverized in a mortar. This pulverized product was filled in a mold and pressure-molded to obtain pellets having a diameter of 18 mm and a thickness of 0.9 mm, and this was used for the positive electrode.

また、負極１４は、次のようにして作製した。メソフェーズ黒鉛化カーボン（日本カーボン社製「Ｐ３Ｂ−ＨＧ」）を黒鉛化処理したものと、ＰＶＤＦとを、質量比で９３：７となるように混合し、この混合物を金型に充填し加圧成形して直径が１９ｍｍ、厚みが０．７ｍｍのペレットとし、これを負極に用いた。 Moreover, the negative electrode 14 was produced as follows. Graphite-treated mesophase graphitized carbon (“P3B-HG” manufactured by Nippon Carbon Co., Ltd.) and PVDF are mixed at a mass ratio of 93: 7, this mixture is filled in a mold and pressurized. Molded into a pellet having a diameter of 19 mm and a thickness of 0.7 mm, this was used for the negative electrode.

内側容器１１の側壁（図２に示す直線部分）の外側全周に、接着層１３に係る樹脂層１１３ｂを構成するための、表面処理を施したポリエチレンフィルム（協立化学産業社製、厚み：５０μｍ）を貼り付け、更に外側容器１２の側壁の内側全周には、接着層１３に係る樹脂層１３ａを構成するための、表面処理を施したポリプロピレンフィルム（協立化学産業社製、厚み：５０μｍ）を貼り付けた。その後、内側容器１１に、負極１４、セパレータ１５、電解液、正極１６の順に装填、注入した。なお、セパレータ１５には、厚みが７μｍのポリエチレン製微孔性フィルム（旭化成社製「ＳＶ」）を用いた。また、電解液には、エチレンカーボネート（ＥＣ）／ジメチルカーボネート（ＤＭＣ）＝１／４（体積比）の混合溶媒に、溶質としてＬｉＰＦ_６を１Ｍの濃度で溶解させたものを用いた。 A polyethylene film (manufactured by Kyoritsu Chemical Industry Co., Ltd., thickness: for forming a resin layer 113b related to the adhesive layer 13 on the entire outer periphery of the side wall of the inner container 11 (the straight portion shown in FIG. 2). 50 μm) and a surface-treated polypropylene film (made by Kyoritsu Chemical Industry Co., Ltd., thickness) for forming the resin layer 13 a related to the adhesive layer 13 on the entire inner periphery of the side wall of the outer container 12. 50 μm) was applied. Thereafter, the negative electrode 14, the separator 15, the electrolytic solution, and the positive electrode 16 were sequentially loaded and injected into the inner container 11. The separator 15 was a polyethylene microporous film (“SV” manufactured by Asahi Kasei Co., Ltd.) having a thickness of 7 μm. As the electrolyte, a solution obtained by dissolving LiPF ₆ as a solute at a concentration of 1M in a mixed solvent of ethylene carbonate (EC) / dimethyl carbonate (DMC) = 1/4 (volume ratio) was used.

発電要素を装填した内側容器１１に、該内側容器１１端部の当接予定位置に絶縁板１７を設置した外側容器１２を被せ、外側容器１２の側壁が外側容器１２の底面に略垂直となるように圧縮して、その後、高周波を用いた誘導加熱により、接着層１３を内側容器１１および外側容器１２に熱融着させて電池を得た。誘導加熱による熱融着は、１９０℃で２秒加熱することで行った。このようにして得られた電池は、外径が２０ｍｍ、厚みが２．５ｍｍの扁平形電池（コイン形電池）である。 The inner container 11 loaded with the power generation element is covered with the outer container 12 provided with an insulating plate 17 at a position where the end of the inner container 11 abuts, and the side wall of the outer container 12 is substantially perpendicular to the bottom surface of the outer container 12. After that, the adhesive layer 13 was thermally fused to the inner container 11 and the outer container 12 by induction heating using a high frequency to obtain a battery. Thermal fusion by induction heating was performed by heating at 190 ° C. for 2 seconds. The battery thus obtained is a flat battery (coin battery) having an outer diameter of 20 mm and a thickness of 2.5 mm.

実施例２
樹脂層１３ｂとするために内側容器１１の外側に貼り付けるフィルムをポリアミドイミドフィルム（東亜合成社製、厚み７０μｍ）に、樹脂層１３ａとするために外側容器１２の内側に貼り付けるフィルムを、表面処理を施したポリプロピレンフィルム（協立化学産業社製、厚み２０μｍ）に、それぞれ変更し、更に樹脂層１３の熱融着条件を、２１０℃、３秒とした他は、実施例１と同様にして電池を作製した。 Example 2
A film to be affixed to the outside of the inner container 11 to form the resin layer 13b is a polyamideimide film (Toa Gosei Co., Ltd., thickness 70 μm), and a film to be affixed to the inside of the outer container 12 to be the resin layer 13a is The same procedure as in Example 1 was conducted except that the film was changed to a treated polypropylene film (produced by Kyoritsu Kagaku Sangyo Co., Ltd., thickness 20 μm), and the heat-sealing conditions for the resin layer 13 were 210 ° C. and 3 seconds. A battery was produced.

比較例
樹脂層１３ｂとするために内側容器１１の外側に貼り付けるフィルムを、ポリプロピレンフィルム（樹脂層１３ａとするために外側容器１２の内側に貼り付けたのと同じもの）に変更した他は、実施例１と同様にして電池を作製した。すなわち、この比較例の電池に係る接着層１３は、実質的にポリプロピレンで構成される単一の層である。 Comparative Example Aside from changing the film attached to the outside of the inner container 11 to make the resin layer 13b to a polypropylene film (the same as that attached to the inside of the outer container 12 to make the resin layer 13a), A battery was produced in the same manner as in Example 1. That is, the adhesive layer 13 according to the battery of this comparative example is a single layer substantially made of polypropylene.

実施例１、２および比較例の各電池（各３０個）について、１ｍＡの定電流で充電を開始し、４．０Ｖになった時点で定電圧充電に切り換え、総充電時間：７５時間で充電を終了し、その後２．０Ｖになるまで１ｍＡで放電する操作を１サイクルとし、これを２サイクルさせた後に１ｍＡの定電流で４．０Ｖになるまで充電した。このように充電した電池を６０℃、相対湿度９０％の環境中で貯蔵し、２０日ごとに漏液状況を観察した。結果を表１に示す。 For each of the batteries of Examples 1 and 2 and the comparative example (30 batteries each), charging was started at a constant current of 1 mA, switching to constant voltage charging when 4.0 V was reached, and total charging time: charging in 75 hours After that, the operation of discharging at 1 mA until 2.0 V was taken as one cycle, and after 2 cycles, the battery was charged with 4.0 mA at a constant current of 1 mA. The battery charged in this way was stored in an environment of 60 ° C. and a relative humidity of 90%, and the leakage state was observed every 20 days. The results are shown in Table 1.

表１中の日数は、貯蔵開始からの日数を意味している。表１から分かるように、実施例１、２の電池では、貯蔵開始から１００日経過後においても、全く漏液が見られなかった。これに対し、比較例の電池では、貯蔵開始から時間が経過するにつれて、漏液する電池の個数が増大しており、これらの電池では、内側容器と接着層との界面から漏液しているのが確認された。 The number of days in Table 1 means the number of days from the start of storage. As can be seen from Table 1, the batteries of Examples 1 and 2 showed no leakage even after 100 days from the start of storage. On the other hand, in the battery of the comparative example, the number of leaking batteries increases as time elapses from the start of storage, and in these batteries, the leakage occurs from the interface between the inner container and the adhesive layer. It was confirmed.

本発明の扁平形電池の一例の要部を示す断面概略図である。It is a cross-sectional schematic diagram which shows the principal part of an example of the flat battery of this invention. 本発明の扁平形電池の他の例の要部を示す断面概略図である。It is a cross-sectional schematic diagram which shows the principal part of the other example of the flat battery of this invention. 本発明の扁平形電池を構成するために好適な内側容器の要部の断面図である。It is sectional drawing of the principal part of an inner side container suitable in order to comprise the flat battery of this invention. 本発明の扁平形電池を構成するために好適な外側容器の要部の断面図である。It is sectional drawing of the principal part of an outer side container suitable in order to comprise the flat battery of this invention. 従来の電池の要部を示す断面概略図である。It is the cross-sectional schematic which shows the principal part of the conventional battery.

符号の説明Explanation of symbols

１０、２０電池
１１、２１内側容器
１２、２２外側容器
１３接着層
１３ａ、１３ｂ樹脂層
１４、２４負極
１５、２５セパレータ
１６、２６正極
２３ガスケット
ＡＡ’ 封止部 10, 20 Battery 11, 21 Inner container 12, 22 Outer container 13 Adhesive layer 13a, 13b Resin layer 14, 24 Negative electrode 15, 25 Separator 16, 26 Positive electrode 23 Gasket A A ′ Sealing part

Claims

内側容器と外側容器とを、それぞれの側壁で嵌合してなる外装体内部に発電要素を封入した扁平形電池であって、
上記内側容器と上記外側容器との嵌合部は、互いに融着温度の異なる樹脂を接着成分として有する２以上の樹脂層を積層してなる接着層が、上記内側容器および上記外側容器に熱融着することで封止されていることを特徴とする扁平形電池。 A flat battery in which a power generation element is enclosed inside an outer package formed by fitting an inner container and an outer container at respective side walls,
The fitting portion between the inner container and the outer container has an adhesive layer formed by laminating two or more resin layers having resins having different fusion temperatures as adhesive components, and the inner container and the outer container are thermally fused. A flat battery characterized by being sealed by wearing.

上記接着層は、外側容器に接する樹脂層の有する樹脂の融解温度が、内側容器に接する樹脂層の有する樹脂の融解温度よりも高い請求項１に記載の扁平形電池。
The flat battery according to claim 1, wherein the adhesive layer has a resin melting temperature of the resin layer in contact with the outer container higher than a resin melting temperature of the resin layer in contact with the inner container.