JP4019722B2

JP4019722B2 - Coin-cell battery

Info

Publication number: JP4019722B2
Application number: JP2002019663A
Authority: JP
Inventors: 望原
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2002-01-29
Filing date: 2002-01-29
Publication date: 2007-12-12
Anticipated expiration: 2022-01-29
Also published as: JP2003217562A

Description

【０００１】
【発明の属する技術分野】
本発明は、発電要素を電池ケースに収納し、上記発電要素に接続されたリードと一方の端子である電池ケース及び他方端子である封口キャップとを抵抗溶接によって接続したコイン型電池の、特にリード先端と電池ケースまたは封口キャップとの溶接部の改良に関するもので、リード先端をその素材に影響されることなく、電池ケースまたは封口キャップと確実に接続することにより、製造コストの低減と電池の信頼性向上を図ったものである。
【０００２】
【従来の技術】
近年、各種ポータブル機器の小型化が進み、小型高容量の電池がこれらの機器の電源に利用され始めた。また大きな放電容量を得るために、活物質として利用率の高い組成物が電池材料として用いられるようになってきた。さらに省スペースの観点から高容量化を図るため正、負極集電体やリードの極薄化が検討されている。
【０００３】
図６（ａ）は近年開発された巻回式の極板群を用いるコイン型電池の断面図であり、図７（ａ）はこのコイン型電池の発電要素１である正極板１１、図７（ｂ）は負極板１２、図７（ｃ）はセパレータ１３のそれぞれ展開図である。
【０００４】
このコイン型電池は、リチウムイオン二次電池として構成した例を示すもので、正極板１１は、アルミニウム箔の両側にコバルト酸リチウムの微粒子を主体とする正極材料を塗布し、アルミニウム箔を一端から長さ６０ｍｍ，幅５ｍｍで延出させて正極リード２とし、負極板１２は銅箔の両側にカーボンの微粒子を主体とする負極材料を塗布し銅箔を一端から長さ４０ｍｍ，幅５ｍｍで延出させて負極リード３としている。また、セパレータ１３には微孔性ポリエチレンフィルムを使用した。
【０００５】
この発電要素１は前記正極板１１と負極板１２とを図７に示すように正極積層面１７ａ〜１７ｅと負極積層面１８ａ〜１８ｆとがセパレータ１３を介して対面し積層されるように正極連結片１９ａ〜１９ｄ及び負極連結片２０ａ〜２０ｅ部分で折り曲げられて巻回される。
【０００６】
次に図６（ａ）に示すように巻回した発電要素１の一方端であるアルミニウム箔製正極リード２は、電池ケース４を形成する外側面ステンレス鋼，内側面アルミニウムのクラッド材のアルミニウムに、レーザー溶接、超音波溶着、または抵抗溶接によって接続される。
【０００７】
他方端である銅箔製負極リード３は例えば、本出願人が先に出願した特願昭２０００−２４１６７９号に示すように、ステンレス鋼製である封口キャップ５の内側面に接続される。この時負極リード３は、図６（ｂ）に示すように溶接性を高めるために抵抗発熱性の高い金属片１０と電池ケース５との間に負極リード３の先端を配置して一対の溶接電極棒８，９で両側から挟み付けた加圧状態で抵抗溶接することによって接続される。
【０００８】
【発明が解決しようとする課題】
このように発電要素から延出されるリード端と電池ケース４及び封口キャップ５とは接続されるのであるが、溶接工法にレーザー溶接法を用いる場合は、設備費が高価なため電池の製造コストが高くなり、かつ溶接の高精度な位置決めが要求される。
【０００９】
また超音波溶接法を用いた場合は、溶接可能な範囲が狭くて溶接条件の設定が難しく、しかも過剰に加圧されたり過剰なエネルギーを加えたりすると被溶接材料にクラックが発生する等の課題を有していた。
【００１０】
また抵抗溶接法を用いる場合は、被溶接材料に電流を流し、その際の被溶接材料の抵抗発熱（ジュール熱）を利用して溶接を行なうが、リードは前記理由によりアルミニウム箔、銅箔等の導電性の高い材料が使用されるため、抵抗比熱が小さく、溶接部を発熱溶融させるためには大電流を必要とする。
【００１１】
しかし、あまりに大きな電流を流すと、封口キャップ５または電池ケース４側が先に大きく溶融して、火花やピンホール等の発生を招くという課題を有している。
【００１２】
そこで、本出願人が先に出願した特願昭２０００−２４１６７９号に示すように、負極リード３をニッケル金属片またはステンレス鋼片と電池ケースとで挟んで抵抗溶接するコイン型電池を提案したが、リードが薄い為に、金属片とリードの間での発熱、およびリードと電池ケースとの間での発熱が同じ温度で生じないために安定した溶接状態を得るのが困難であった。近年、電池容量向上のため正負リードは益々薄くなる傾向にあり、前述の困難さが深まっている。
【００１３】
本発明では、この溶接状態を簡単な操作で安定化させると共に、安価にリード先端と電池ケースまたは封口キャップとの接続が確実な電池を提供することを目的とする。
【００１４】
【課題を解決するための手段】
上記目的を達成するために、
本願発明では、正負の極板とセパレータを介して巻回した発電要素の正極および負極にそれぞれ一端が接続されたリードの他端を、一方極の端子をなす電池ケース及び他方極端子をなす封口キャップの内側に、それぞれ接続したコイン型電池において、
リードの他端と電池ケースまたは封口キャップとが接した状態で、リードよりも抵抗発熱性が高くリードに相対向した面に凹凸状に加工された金属片を当接し、リードの他端を金属片と電池ケースまたは封口キャップとの間に挟み、これら三者が抵抗溶接で一体化して発電要素より導出したリードの他端と電池ケースまたは封口キャップとを接合したものである。
【００１５】
上述のように、リードよりも抵抗発熱性が高く、前記リードに相対向した面に凹凸状に加工された金属片を溶接用部材として用いて抵抗溶接を行なえば、その凸面は確実にリードに接触し、かつ電池ケースまたは封口キャップに小さな接触面積で広い範囲において接触するので凸面部分に通電電流が集中して、この部分が高いジュール熱を発生する。
【００１６】
このように、リードに相対向した面の金属片の表面に凹凸を形成させると、低電流で大きな抵抗発熱を得ることが出来、その熱はリードと電池ケースの両方に伝播される。これにより、十分な溶接部を形成することができ確実な溶接箇所の確保と、機械的強度の向上につながる。また、低電流で溶接を行うことができるため、火花、ピンホールの発生等を発生させることなく溶接を行うことができる。
【００１７】
このとき、上記において、負極リードの幅より大きい金属片を用いることが好ましい。これにより、溶接を行う位置を固定することが困難な三層溶接において溶接を行う位置の自由度を広くすることができる。また、発熱によって溶融した溶融材を封じ込めることができ、一層の機械的強度の向上を図ることができる。
【００１８】
さらに好ましくは、リードに孔を一ヶ所以上穿ち、前記リードよりも抵抗発熱性が高く前記リードに相対向した面に凹凸のある金属片を用い、金属片と電池ケースまたは封口キャップをナゲットのできやすい材質と厚みを選ぶことによって、合金化し難い材質のリードに孔をあけ、この孔を介して前記ナゲットを生じさせることによって、リードをリベットのように挟み込むことができる。
【００１９】
このとき、リードよりも抵抗発熱性が高く前記リードに相対向した面に凹凸のある金属片の凸部に略一致する孔を一ヶ所以上穿つことが好ましい。前記ナゲットのできる位置と前記リードの孔位置をあらかじめ一致させておくことにより一層確実にリードをリベットのように挟み込むことができる。
【００２０】
さらに好ましくは、リードよりも抵抗発熱性が高く前記リードに相対向した面に凹凸のある金属片が、リードよりも厚くする。金属片を厚くすることによって、溶接部をより一層確実に封じ込め、火花を防ぐことができる。
【００２１】
このとき、前記リードよりも抵抗発熱性が高く前記リードに相対向した面に凹凸のある金属片の材質がニッケルまたはニッケル合金であることが好ましい。
【００２２】
上記ではコイン型電池に付いて記述したが、同質の材料を用いるリチウム一次電池やリチウム二次電池の円筒型電池、角型電池、偏平角型電池等に付いても本願発明を用い得ることは、いうまでもない。
【００２３】
【発明の実施の形態】
以下、添付図面を参照して本発明の２つの実施形態について説明する。２つの実施形態の共通部分に付いてまず説明する。
【００２４】
図１は本発明の実施形態での、直径３０ｍｍ，厚さ３．５ｍｍのリチウムイオン電池の断面図であり同（ｂ）、（ｃ）はそのリード溶接部の拡大断面図である。図において、発電要素１は前記同様正極板、セパレータおよび負極板を積層巻回して構成されていて、厚さ２０μｍのアルミニウム箔からなる長さ６０ｍｍ，幅５ｍｍの正極リード２は電池ケース４の内面に、厚さ２０μｍの銅箔からなる負極リード３は封口キャップ５の内面にそれぞれ凹凸のある溶接用金属片７で裏打ちされた状態に溶接されている。
【００２５】
以下図２および図３を用いて本発明の第１の実施形態について説明する。
【００２６】
図２に示すように、銅箔製負極リード３の先端を、封口キャップ５の内面中央部に引出し、リードよりも幅広い正方形状で厚さが例えば４０μｍ、リードと対向する片面に８μｍ〜８０μｍのピッチでクロス状の筋目を施したニッケル箔からなる金属片７が上側に押し当てられて、前記リードと共に、溶接される。なお、図２中６は、ケース周縁部に予め取付けられた絶縁封口用ガスケットである。
【００２７】
リードの溶接は、図４に拡大して示すように、金属片７の上側と封口キャップ５の下側に溶接電極棒８，９をそれぞれあてがい２点の溶接部を形成する溶接過程を２度行うことで合計４点の溶接部を形成した。電極棒８，９で上下から挟まれた金属片７、銅箔リード３の先端、封口キャップ５の三者は加圧接触して、対向した２本の電極棒８，９間を流れる溶接電流が、金属片７のクロス状筋目とリードとの接触部に集中し、そのうちの電極棒で最も強く加圧された２ヶ所が溶融すると同時に下側のケース対応箇所の抵抗発熱とあいまって一体に溶接される。この処方で図４の実線位置で示す電極棒を、２点鎖線位置に移動させて通電することで、Ａ，Ｂ２ヶ所ずつ合計４点の溶接部を形成できる。
【００２８】
図２の（ａ）はリードが溶接された封口キャップを示す平面図であり、金属片７は確実にリード先端を覆って、４点の溶接部でリードをケースに接続している。金属片７に設ける凹凸部は、図３（ａ）のクロス状筋目７−１のほか、同（ｂ）に示すリード側に向けて突出したくぼみを等間隔で複数設けた７−２や、同（ｃ）のように金属片７全体を波板状に加工したもの７−３でもよく、いずれもリードとは部分的に接触して、その接触部に発熱を集中させることができる。
【００２９】
また、リードは銅箔のほか、この電池の正極で用いられるアルミニウム箔であっても同様に処理でき、厚さの薄いアルミニウム箔リードを、それよりも厚さの厚い金属片と封口キャップとの間に挟み込んで、前記金属片と共に、抵抗溶接することができる。いずれの場合も、厚さの薄いリード先端は、これより厚さが厚い二つの部材に挟まれているので、溶接時の過大溶断やピンホール等を生じることなく溶接できる。
【００３０】
リード先端を挟み込んで溶接する金属片は、上記の例ではニッケル箔を用いたが、これ以外にニッケル合金やニッケルメッキ鋼でもよく、リードよりも抵抗発熱性の高い材料で、かつ厚く、大きく形成されていればよい。
【００３１】
次に図５を用いて本発明の第２の実施形態に付いて説明する。
【００３２】
ここで説明する被溶接物は、本発明の第１の実施形態と同じく負極リードと電池ケースである。図５（ａ）に示すように、銅箔製負極リード３の先端にあらかじめ４個の直径０．８ｍｍ孔を穿つ、ついで図５（ｂ）に示すような、ニッケル製金属片を準備する。このニッケル金属片は本発明の第１の実施形態７−２と同じ形状をしており、リード側に向けて突出したくぼみが４ヶ所設けられている。この４ヶ所のくぼみと前記負極リード３の４個の孔は同一のピッチであり、突出した凸部の外径と孔径は略一致している。
【００３３】
リード溶接は、図５（ｃ）に示すように、金属片７−２をこの凸部と負極リード３の孔を各々一致させて封口キャップ５とで負極リード３を電極棒８，９で挟み、加圧通電して行う。この溶接で金属片７−２は、この凸部と電池ケース５の間が発熱してナゲットができると共に、負極リード３をリベットの如くかしめる。孔径が凸部径より小径の場合、前記発熱より負極リード３の孔の周辺が溶融し金属片７−２および封口キャップ５と密着状態になる。
【００３４】
ナゲットのできる第２の実施形態は、第１の実施形態に比較して、ナゲットの生じ難いリードが間に無いので溶接強度を格段に向上させることができる。
【００３５】
上記の処理で正極リード２及び負極リード３がそれぞれ溶接された電池ケース４を封口キャップ５に被せ、電池ケース４の開口端側を内側に折り曲げるカシメ加工により、図１（ａ）に示すように、封口キャップ４と電池ケース５とガスケット６で形成される密閉容器内に回構造の極板群１を収容したコイン型電池が完成する。
【００３６】
【発明の効果】
以上の説明の通り、本発明によれば、正極・負極リードと電池ケースおよび封口キャップとを抵抗溶接法によって確実に接続できることにより、製造コストの低減と電池の信頼性の向上とを図ることができると共に、十分な溶接部を形成することにより集電性が良好で内部抵抗の低いコイン型電池を提供することができる。
【図面の簡単な説明】
【図１】（ａ）本願発明のコイン型電池の断面図
（ｂ）同電池ケースとリードとの溶接部の拡大断面図
（ｃ）同封口キャップとリードとの溶接部の拡大断面図
【図２】（ａ）本願実施の形態による電池の封口キャップとリードとの溶接状態を示す平面図
（ｂ）同断面図
【図３】（ａ）第１の実施形態を示す溶接用金属片の表面状態を示す図
（ｂ）別な金属片の表面状態を示す図
（ｃ）さらに別な金属片の表面状態を示す図
【図４】本願発明の第１の実施形態示す封口キャップへのリード溶接時の状態図
【図５】（ａ）本願発明の第２の実施形態を示すリード先端の平面図
（ｂ）同金属片の平面図と断面図
（ｃ）同封口キャップへのリード溶接時の状態を示す断面図
【図６】（ａ）従来のコイン型電池の構成を示す断面図
（ｂ）同電池の封口キャップにリードを溶接する際の説明図
【図７】（ａ）巻回した発電要素の正極板展開図
（ｂ）同負極板展開図
（ｃ）同セパレータ展開図
【符号の説明】
１巻回した発電要素
２正極リード
３負極リード
４電池ケース
５封口キャップ
６ガスケット
７溶接用金属片
８溶接電極棒
９溶接電極棒[0001]
BACKGROUND OF THE INVENTION
The present invention particularly relates to a coin-type battery in which a power generation element is housed in a battery case, and a lead connected to the power generation element is connected to a battery case as one terminal and a sealing cap as the other terminal by resistance welding. This relates to the improvement of the weld between the tip and the battery case or sealing cap. The lead tip is not affected by the material, and the battery case or sealing cap is securely connected to reduce manufacturing costs and battery reliability. This is intended to improve performance.
[0002]
[Prior art]
In recent years, various portable devices have been miniaturized, and small and high-capacity batteries have begun to be used as power sources for these devices. In order to obtain a large discharge capacity, a composition having a high utilization rate as an active material has been used as a battery material. Furthermore, from the viewpoint of space saving, ultrathinning of positive and negative electrode current collectors and leads has been studied in order to increase the capacity.
[0003]
FIG. 6A is a cross-sectional view of a coin-type battery using a winding-type electrode plate group developed in recent years, and FIG. 7A is a positive electrode plate 11 that is a power generation element 1 of this coin-type battery. FIG. 7B is a development view of the negative electrode plate 12, and FIG.
[0004]
This coin type battery shows an example configured as a lithium ion secondary battery. A positive electrode plate 11 is formed by applying a positive electrode material mainly composed of fine particles of lithium cobaltate on both sides of an aluminum foil, and the aluminum foil from one end. The negative electrode plate 12 is coated with a negative electrode material mainly composed of carbon fine particles on both sides of the copper foil, and the copper foil is extended from one end to a length of 40 mm and a width of 5 mm. The negative lead 3 is taken out. The separator 13 was a microporous polyethylene film.
[0005]
In the power generating element 1, the positive electrode plate 11 and the negative electrode plate 12 are connected to each other so that the positive electrode laminate surfaces 17a to 17e and the negative electrode laminate surfaces 18a to 18f face each other via the separator 13 as shown in FIG. The pieces 19a to 19d and the negative electrode connecting pieces 20a to 20e are bent and wound.
[0006]
Next, as shown in FIG. 6 (a), the positive electrode lead 2 made of aluminum foil, which is one end of the power generating element 1 wound, is formed on the aluminum of the cladding material of the outer surface stainless steel and the inner surface aluminum forming the battery case 4. Connected by laser welding, ultrasonic welding, or resistance welding.
[0007]
The negative electrode lead 3 made of copper foil at the other end is connected to the inner surface of the sealing cap 5 made of stainless steel, as shown in, for example, Japanese Patent Application No. 2000-241679 previously filed by the present applicant. At this time, as shown in FIG. 6B, the negative electrode lead 3 has a pair of welds in which the tip of the negative electrode lead 3 is disposed between the metal piece 10 having high resistance heat generation and the battery case 5 in order to improve weldability. The electrodes 8 and 9 are connected by resistance welding in a pressurized state sandwiched from both sides.
[0008]
[Problems to be solved by the invention]
Thus, the lead end extended from the power generation element is connected to the battery case 4 and the sealing cap 5. However, when the laser welding method is used for the welding method, the manufacturing cost of the battery is high because the equipment cost is high. Higher positioning with high accuracy is required.
[0009]
In addition, when using the ultrasonic welding method, it is difficult to set the welding conditions because the weldable range is narrow, and there are problems such as cracking in the welded material if excessive pressure is applied or excessive energy is applied. Had.
[0010]
When resistance welding is used, a current is passed through the material to be welded, and welding is performed using the resistance heat generation (Joule heat) of the material to be welded. Therefore, the specific heat of resistance is small, and a large current is required to heat and melt the weld.
[0011]
However, when an excessively large current is applied, the sealing cap 5 or the battery case 4 side is melted first and causes a spark, a pinhole or the like.
[0012]
Therefore, as shown in Japanese Patent Application No. 2000-241679 filed earlier by the present applicant, a coin-type battery in which the negative electrode lead 3 is sandwiched between a nickel metal piece or a stainless steel piece and a battery case has been proposed. Since the lead is thin, heat generation between the metal piece and the lead and heat generation between the lead and the battery case do not occur at the same temperature, so it is difficult to obtain a stable welded state. In recent years, positive and negative leads tend to become thinner and thinner to improve battery capacity, and the above-mentioned difficulties are deepening.
[0013]
An object of the present invention is to provide a battery in which the welding state is stabilized by a simple operation and the lead tip and a battery case or a sealing cap are securely connected at low cost.
[0014]
[Means for Solving the Problems]
To achieve the above objective,
In the present invention, the other end of the lead, one end of which is connected to the positive electrode and the negative electrode of the power generation element wound through the positive and negative electrode plates and the separator, respectively, the battery case forming one terminal, and the sealing forming the other electrode terminal In the coin type battery connected to the inside of the cap,
With the other end of the lead in contact with the battery case or sealing cap, a metal piece processed into a concavo-convex shape is brought into contact with the surface opposite to the lead, which has higher resistance heat generation than the lead, and the other end of the lead is made of metal. The other end of the lead, which is sandwiched between the piece and the battery case or the sealing cap, is integrated by resistance welding and led out from the power generation element, and the battery case or the sealing cap is joined .
[0015]
As described above, if resistance welding is performed using a metal piece processed into a concavo-convex shape on a surface opposite to the lead as a welding member, the convex surface is surely formed into the lead. In contact with the battery case or the sealing cap in a wide range with a small contact area, the energizing current concentrates on the convex surface portion, and this portion generates high Joule heat.
[0016]
Thus, when unevenness is formed on the surface of the metal piece opposite to the lead , a large resistance heat can be obtained at a low current, and the heat is transmitted to both the lead and the battery case. As a result, it is possible to form a sufficient welded portion, thereby ensuring a reliable weld location and improving the mechanical strength. In addition, since welding can be performed at a low current, welding can be performed without generating sparks or pinholes.
[0017]
At this time, in the above, it is preferable to use a metal piece larger than the width of the negative electrode lead. Thereby, the freedom degree of the position which welds in the three-layer welding where it is difficult to fix the position which welds can be expanded. In addition, the molten material melted by the heat generation can be contained, and the mechanical strength can be further improved.
[0018]
More preferably, one or more holes are formed in the lead, a metal piece having higher resistance heat generation than the lead and having irregularities on the surface opposite to the lead, and the metal piece and the battery case or the sealing cap can be nugged. By selecting an easy material and thickness, a lead is made in a material that is difficult to be alloyed, and the nugget is generated through the hole, whereby the lead can be sandwiched like a rivet.
[0019]
At this time, it is preferable that at least one hole having a resistance exothermic property higher than that of the lead and substantially coinciding with the convex portion of the metal piece having concavities and convexities on the surface facing the lead is formed. By aligning the position where the nugget can be formed and the hole position of the lead in advance, the lead can be sandwiched more reliably like a rivet.
[0020]
More preferably, the metal piece having higher resistance heat generation than the lead and having irregularities on the surface facing the lead is made thicker than the lead. By thickening the metal piece, it is possible to contain the welded portion more reliably and prevent sparks.
[0021]
At this time, it is preferable that the material of the metal piece which has higher resistance heat generation than the lead and has irregularities on the surface facing the lead is nickel or a nickel alloy.
[0022]
In the above description, the coin type battery is described. However, the present invention can also be used for a lithium primary battery, a lithium secondary battery cylindrical battery, a rectangular battery, a flat rectangular battery, etc., using the same material. Needless to say.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, two embodiments of the present invention will be described with reference to the accompanying drawings. The common part of the two embodiments will be described first.
[0024]
FIG. 1 is a cross-sectional view of a lithium ion battery having a diameter of 30 mm and a thickness of 3.5 mm according to an embodiment of the present invention. FIGS. 1B and 1C are enlarged cross-sectional views of the lead welded portion. In the figure, the power generating element 1 is constructed by laminating and winding a positive electrode plate, a separator and a negative electrode plate as described above, and the positive electrode lead 2 made of aluminum foil with a thickness of 20 μm and having a length of 60 mm and a width of 5 mm is the inner surface of the battery case 4. In addition, the negative electrode lead 3 made of a copper foil having a thickness of 20 μm is welded in a state where the inner surface of the sealing cap 5 is lined with a metal piece 7 having unevenness.
[0025]
The first embodiment of the present invention will be described below with reference to FIGS.
[0026]
As shown in FIG. 2, the tip of the copper foil negative electrode lead 3 is drawn out to the center of the inner surface of the sealing cap 5, has a square shape wider than the lead and has a thickness of, for example, 40 μm, and is 8 μm to 80 μm on one side facing the lead. A metal piece 7 made of nickel foil having cross-shaped lines with a pitch is pressed upward and welded together with the lead. In addition, 6 in FIG. 2 is the gasket for insulation sealing previously attached to the case peripheral part.
[0027]
As shown in an enlarged view of FIG. 4, the welding of the lead is performed by performing a welding process in which welding electrode rods 8 and 9 are respectively applied to the upper side of the metal piece 7 and the lower side of the sealing cap 5 to form a two-point weld. In total, four welds were formed. The metal piece 7 sandwiched from above and below by the electrode rods 8, 9, the tip of the copper foil lead 3, and the sealing cap 5 are in pressure contact, and the welding current flowing between the two electrode rods 8, 9 facing each other. However, it concentrates on the contact part between the cross-shaped streak of the metal piece 7 and the lead, and at the same time, the two parts that are most strongly pressed by the electrode rod melt, and at the same time, combined with the resistance heat generation at the corresponding part of the lower case Welded. By moving the electrode rod indicated by the solid line position in FIG. 4 to the two-dot chain line position and energizing with this prescription, a total of four welds can be formed for each of A and B.
[0028]
FIG. 2A is a plan view showing the sealing cap to which the lead is welded. The metal piece 7 reliably covers the lead tip, and the lead is connected to the case at four welds. The uneven part provided in the metal piece 7 includes 7-2 provided with a plurality of depressions protruding toward the lead side shown in FIG. As in (c), the metal piece 7 as a whole may be processed into a corrugated plate 7-3, both of which are in partial contact with the lead and can concentrate heat generation at the contact portion.
[0029]
In addition to the copper foil, the lead can be processed in the same way even if it is an aluminum foil used in the positive electrode of this battery. It is possible to perform resistance welding together with the metal piece by sandwiching them. In either case, the lead tip having a small thickness is sandwiched between two members having a larger thickness, and therefore can be welded without causing excessive fusing or pinholes during welding.
[0030]
The metal piece to be welded with the tip of the lead sandwiched was nickel foil in the above example, but in addition to this, a nickel alloy or nickel-plated steel may be used, and it is made of a material that has higher resistance heat generation than the lead, and is thick and large. It only has to be done.
[0031]
Next, a second embodiment of the present invention will be described with reference to FIG.
[0032]
The workpieces described here are the negative electrode lead and the battery case as in the first embodiment of the present invention. As shown in FIG. 5A, four 0.8 mm diameter holes are drilled in advance at the tip of the copper foil negative electrode lead 3, and then a nickel metal piece as shown in FIG. 5B is prepared. This nickel metal piece has the same shape as that of the first embodiment 7-2 of the present invention, and is provided with four recesses protruding toward the lead side. The four recesses and the four holes of the negative electrode lead 3 have the same pitch, and the outer diameter and the hole diameter of the protruding protrusions are substantially the same.
[0033]
In lead welding, as shown in FIG. 5 (c), the metal piece 7-2 is sandwiched between the projection cap and the hole of the negative electrode lead 3, and the negative electrode lead 3 is sandwiched between the electrode bars 8 and 9 with the sealing cap 5. , Conducted by applying pressure. With this welding, the metal piece 7-2 generates heat between the projection and the battery case 5 to form a nugget, and the negative electrode lead 3 is crimped like a rivet. When the hole diameter is smaller than the diameter of the convex portion, the periphery of the hole of the negative electrode lead 3 is melted by the heat generation and is brought into close contact with the metal piece 7-2 and the sealing cap 5.
[0034]
Compared with the first embodiment, the second embodiment capable of forming a nugget can significantly improve the welding strength because there are no leads in which nuggets are unlikely to occur.
[0035]
As shown in FIG. 1A, the battery case 4 to which the positive electrode lead 2 and the negative electrode lead 3 are welded by the above processing is covered with the sealing cap 5, and the opening end side of the battery case 4 is bent inward. Thus, a coin-type battery in which the electrode plate group 1 having a rotating structure is accommodated in a sealed container formed by the sealing cap 4, the battery case 5, and the gasket 6 is completed.
[0036]
【The invention's effect】
As described above, according to the present invention, the positive and negative electrode leads, the battery case, and the sealing cap can be reliably connected by the resistance welding method, thereby reducing the manufacturing cost and improving the reliability of the battery. In addition, by forming a sufficient welded portion, it is possible to provide a coin-type battery with good current collection and low internal resistance.
[Brief description of the drawings]
1A is a cross-sectional view of a coin-type battery of the present invention, FIG. 1B is an enlarged cross-sectional view of a welded portion between the battery case and a lead, and FIG. 1C is an enlarged cross-sectional view of a welded portion between the sealing cap and the lead. 2A is a plan view showing a welded state between a battery sealing cap and a lead according to an embodiment of the present invention. FIG. 3B is a cross-sectional view of the battery. FIG. FIG. 4B shows the surface state of another metal piece. FIG. 4C shows the surface state of another metal piece. FIG. 4 shows lead welding to the sealing cap according to the first embodiment of the present invention. FIG. 5A is a plan view of the tip of a lead showing a second embodiment of the present invention, FIG. 5B is a plan view of the metal piece, and a cross-sectional view of the metal piece. FIG. FIG. 6 is a cross-sectional view showing a state of the battery. FIG. 6A is a cross-sectional view showing the configuration of a conventional coin-type battery. Illustration 7 when welding the lead-up (a) a positive electrode plate developed view of a power generating element formed by winding (b) the negative electrode plate developed view (c) the separator exploded view EXPLANATION OF REFERENCE NUMERALS
1 Winding power generation element 2 Positive electrode lead 3 Negative electrode lead 4 Battery case 5 Seal cap 6 Gasket 7 Metal piece for welding 8 Welding electrode rod 9 Welding electrode rod

Claims

The other end of the lead, one end of which is electrically connected to the positive electrode and the negative electrode of the power generating element wound with the positive and negative electrode plates and the separator, respectively, the battery case forming one terminal, and the inside of the sealing cap forming the other electrode terminal In each coin cell battery connected to
In a state where the other end of the lead is in contact with the battery case or the sealing cap, a metal piece having a concavo-convex shape is brought into contact with the surface opposite to the lead, which has higher resistance heat generation than the lead, and the other end of the lead Is a coin-type battery in which the other end of the lead led out from the power generation element and the battery case or sealing cap are joined together by resistance welding and sandwiched between the metal piece and the battery case or sealing cap .

In a state where the other end of the lead is in contact with the battery case or the sealing cap , a metal piece having higher resistance heat generation than the lead and having irregularities on the surface facing the lead is sufficient to cover the other end of the lead. The coin-type battery according to claim 1, wherein the coin-type battery is formed wider than the other end of the lead.

With the other end of the lead in contact with the battery case or the sealing cap, the other end of the lead is perforated with one or more through holes, and this part has a higher resistance to heat generation than the lead. The coin-type battery according to claim 1 or 2, wherein the three members are integrated by resistance welding by being sandwiched between a metal piece having irregularities on opposite surfaces and a battery case or a sealing cap.

In a state where the other end of the lead is in contact with the battery case or the sealing cap, the other end of the lead is at one or more positions where the other end of the lead substantially coincides with the convex portion of the metal piece having an uneven surface on the surface opposite to the lead. The coin-type battery according to claim 3, wherein a through hole is formed.

The coin-type battery according to any one of claims 1 to 4, wherein the metal piece having a high resistance exothermic property and having irregularities on a surface facing the lead is thicker than the lead.

The lead is formed of aluminum, copper, or an alloy thereof, and a metal piece having a resistance heat generation property higher than that of the lead and having irregularities on the surface facing the lead is formed of a nickel or nickel alloy plate or foil. The coin-type battery according to claim 1.