JP2004022479A

JP2004022479A - Battery and its manufacturing method

Info

Publication number: JP2004022479A
Application number: JP2002179378A
Authority: JP
Inventors: Toshiharu Kitagawa; 北川　俊治; Masaaki Kaneda; 金田　正明; Kanehito Masumoto; 増本　兼人; Ryuichiro Ebi; 海老　龍一郎
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2002-06-20
Filing date: 2002-06-20
Publication date: 2004-01-22
Anticipated expiration: 2022-06-20
Also published as: JP4191433B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin battery constituted of a simple structure. <P>SOLUTION: Electrode plate groups 4 are housed in a battery case 2 in which a concave 5 and a welding margin 8 are formed around it, and by covering the welding margin 8, with a cover plate 3 and by carrying out seam-welding to the welding margin 8, the inside of the concave 5 is sealed. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、角形電池の薄型化を可能にする構造を備えた電池とその製造方法に関するものである。
【０００２】
【従来の技術】
携帯電話機やＰＤＡなどの携帯電子機器は、高機能化と共に小型化、薄型化の進展が著しく、それに適用する電池に小型、薄型にして高エネルギー密度であることが要求され、これに対応する電池として扁平角形のリチウムイオン二次電池の需要が増加している。携帯電子機器の最近の傾向は、小型化よりむしろ薄型化の方向にあり、ポケットやバッグに入れやすく、使いやすさを損なうことがないため、薄型化を競う商品も見受けられる。
【０００３】
機器の薄型化を達成するためには、その電源である電池により薄型化が要求されるが、現在実用化されている電池ケースの製造方法では薄型化に限度がある。電池ケースは絞り加工や扱き加工によって形成されるので、加工方向の深さに対して開口面積が小さくなるほどに加工が困難になり、極板群を電池ケース内に挿入することも困難になる。現状の扁平角形電池の更なる薄型化を図るためには、電池ケースの構造を根本的に変える必要があり、電池ケースを半殻体に形成し、極板群を収容して後、平板もしくは半殻体の蓋体により電池ケースを閉じる電池構造が開発されている。
【０００４】
例えば、特開平９−２１３２８６号公報に開示された電池は、半殻体に形成された容器内に極板群を収容し、容器の開口部に蓋板を配し、蓋板の周囲を容器にレーザー溶接することにより容器内を封止している。このような半殻体の電池ケースの大きな開口部を平板で封止する構造は、特開２００１−５２６５８号公報にも開示されており、半殻体に形成された電池ケースの開口端に電池蓋が嵌まり合う段差部を形成し、極板群を電池ケース内に収容して後、前記段差部に電池蓋を嵌め込み、電池蓋と電池ケースとをその周囲でレーザー溶接することにより電池ケース内を封止している。
【０００５】
また、特開２００１−１６７７４４号公報に開示された電池は、鍔部を設けた一対の半殻体の部材の凹部内に極板群を収容し、鍔部で両部材を溶接することにより、極板群を収容した両部材の間を封止している。
【０００６】
【発明が解決しようとする課題】
上記各従来技術において、電池ケースの極板群を収容した凹部を封止するために蓋体の周辺部を半殻体に周囲に溶接する工程はレーザー溶接が用いられている。レーザー溶接は設備コストが高く、レーザーパワーの選択が困難で、パワーが弱いと反射によって熱の吸収率が低くなって溶融させるまでに時間がかかり、パワーを強くすると急激に加熱されるために溶融物が飛散してピンホールやクラックが発生しやすくなる。
【０００７】
また、レーザー溶接する部分は、極板群に対する熱影響を軽減させるために電池ケースと蓋体とを突き合わせた端縁でなされるが、電池ケースと蓋体との隙間を溶融物で充填するように溶接されるので、溶接後に窪みが発生しやすく、窪みの発生は溶接強度の低下をまねきやすい問題がある。
【０００８】
本発明が目的とするところは、極板群を収容した電池ケースを蓋体で閉じる溶接工法の改良により安価に薄型の電池を構成できるようにした電池及びその製造方法を提供することにある。
【０００９】
【課題を解決するための手段】
上記目的を達成するための本願第１発明に係る電池は、金属板を加工して凹部の開口周囲にフランジを設けた半殻体に電池ケースが形成され、前記凹部内に極板群を収容して前記フランジに周辺部を重ね合わせて配設された金属製の蓋板とフランジとの間がシーム溶接により接合されてなることを特徴とする。
【００１０】
上記構成によれば、電池ケースの加工が容易になされ、極板群の収容も容易に行うことができる。この電池ケースの封止は円板電極を回転移動させながら蓋板の溶接を線状に連続形成できるシーム溶接によってなされるので、加工コストが削減でき、極板群に対して悪影響を及ぼすことなく封止加工することができる。
【００１１】
上記各構成において、凹部の端部に深さを減少させた段差部が形成され、この段差部に極板群を構成する正極板及び負極板にそれぞれ接続して外部露出する正極及び負極の外部接続端子を設けると、電池の厚さ範囲内で外部接続を行うことができ、小型薄型化された機器での電池接続を容易に実施できる。
【００１２】
また、本願第２発明に係る電池の製造方法は、金属板をプレス加工して、凹部と、その周囲にフランジ状に設けた溶接代と、前記凹部内から外部に通じる開口部とを設けた半殻体に電池ケースを形成し、前記開口部にガスケットを介して外部接続端子を取り付けて開口部を封止し、前記外部接続端子に接続した極板群を電池ケース内に収容し、電池ケースの開放部側に蓋板を配して蓋板の周辺部と溶接代との間をシーム溶接して電池ケース内を封止し、電池ケースの任意位置に形成した注入口から電池ケース内に電解液を注入し、前記注入口を封栓により閉じることを特徴とする。
【００１３】
上記製造方法によれば、極板群を収容した電池ケースと蓋板との間は円板電極を回転移動させながら溶接を線状に連続形成するシーム溶接によって接合されるので、レーザー溶接による溶融接合と異なり、溶接時に極板群に与える熱影響が少なく、微小な隙間（クラック）が生じることがないので密封性の低下を引き起こすことがなく、安価な装置構成により電池ケースの封止が可能である。
【００１４】
上記製造方法において、蓋板又は溶接代に、対向する相手側に向けて突出する突出部を連続的に形成し、シーム溶接がプロジェクション溶接を加味してなされるようにすることにより、接合をより確実に実施することができる。
【００１５】
【発明の実施の形態】
以下、添付図面を参照して本発明の実施形態について説明し、本発明の理解に供する。尚、以下に示す実施形態は本発明を具体化した一例であって、本発明の技術的範囲を限定するものではない。
【００１６】
図１は、本実施形態に係る電池１の外観形状を示すもので、扁平な角形のリチウムイオン二次電池として構成されたものである。この電池１は、図２に各構成要素に分解して示すように、半殻体に形成された電池ケース２内に極板群４を収容し、電池ケース２の開放部を蓋板３で封止するように構成されている。前記電池ケース２と蓋板３の金属板の材質としては特に限定されるものでなく、ニッケルメッキ鋼鈑、ステンレス、アルミニウム合金を用いることができ、その厚さは０．４ｍｍ以下が好ましく、０．１ｍｍ〜０．３ｍｍの範囲が好適であり、電池ケース２と蓋板３とは同じ材質のものを用いることがシーム溶接の容易性、信頼性の観点から好ましい。
【００１７】
図２に示すように、電池ケース２は、金属板をプレス加工して段差部６を設けた凹部５を形成すると共に、凹部５の周囲にフランジ状に溶接代８を設けて形成される。前記段差部６は正極及び負極の外部接続端子を形成する部位で、ここでは段差部６に形成された端子孔７に外ガスケット１１及び内ガスケット１２で電池ケース２と絶縁すると共に気密性を確保して正極外部接続端子とするリベット１０が締結固定される。また、段差部６には電解液の注入口１４が形成されている。
【００１８】
前記電池ケース２の凹部５内には、正極板と負極板とをセパレータを介して巻回した極板群４が収容される。図２に示す極板群４の正極板から引き出された正極リード１５は前記リベット１０に接合され、負極板から引き出された負極リード１６は段差部６上に接合される。極板群４の構成は正極板及び負極板の巻回方向を長手方向にして、図４に示すように構成することもできる。図４に示す極板群４ａは、正極板と負極板とをセパレータを介して長手方向に巻回し、正極リード１５を正極板の終端部（巻端）から引き出し、負極リード１６を負極板の終端部（巻端）から引き出したもので、正極リード１５のリベット１０への接合、負極リード１６の段差部６上への接合が容易で、接合の確実性を向上させることができる。
【００１９】
極板群４を収容した電池ケース２の開放部上には蓋板３が被せられ、蓋板３の周辺部と前記溶接代８との間がシーム溶接されることにより、電池ケースの凹部５は蓋板３によって封止される。前記シーム溶接は周知のように円板電極を回転移動させながら溶接を線状に連続形成するもので、溶接代８と蓋板３との当接面が溶融したナゲットが連続して形成されるので、凹部５内は封止される。
【００２０】
図３に示すように、溶接代８又は蓋板３の溶接線上にプロジェクション（突出部）２４を線状に形成しておくと、プロジェクション２４とその当接部分に集中的な抵抗発熱が伴い、溶融したとき加圧力により圧し潰されるので、シーム溶接にプロジェクション溶接を加味した確実な溶接がなされる。
【００２１】
封止された凹部５内には、前記電解液注入口１４から所定量の電解液が注入され、注入完了後に電解液注入口１４には封栓１３が挿入され、段差部に封栓１３を溶接することにより凹部５内は密封される。
【００２２】
上記製造手順により製造された電池１は、図１に示すように段差部６上に形成されたリベット１０を正極外部接続端子とし、段差部６の面を負極外部接続端子として外部接続の用に供することができる。正極及び負極の外部接続端子が段差部６上に形成されていることにより、外部接続端子に接続したリードを電池１の厚さ内で処理することができる。また、外部接続端子に接触接続させる場合にも電池１の厚さ内に接触構造を構成することができる。従って、薄型に構成した電池１の特質を損なうことなく機器に装着することができる。
【００２３】
【発明の効果】
以上の説明の通り本発明によれば、発電要素を収容する電池容器の構造は、金属板を半殻体に加工した電池ケースの開放部に金属製の蓋体をシーム溶接することによって封止する構造に構成されるので、設備コストや加工コストを少なくして薄型の電池に構成することができる。また、電池の厚さより薄くした段差部上に外部接続端子が形成されているので、電池の厚さ内で接続処理を行うことができ、薄型電池の特質を損なうことなく接続構造を設けることができる。
【図面の簡単な説明】
【図１】実施形態に係る電池の外観形状を示す斜視図。
【図２】同上電池の各構成要素を示す分解斜視図。
【図３】プロジェクションを設けた構成を示す部分断面図。
【図４】極板群の別構成を適用した分解斜視図。
【符号の説明】
１　電池
２　電池ケース
３　蓋板
４、４ａ　極板群
５　凹部
６　段差部
８　溶接代
１０　リベット（外部接続端子）
１１　外ガスケット
１２　内ガスケット
１３　封栓[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a battery having a structure that enables a thinner rectangular battery and a method for manufacturing the same.
[0002]
[Prior art]
Mobile electronic devices, such as mobile phones and PDAs, have been significantly reduced in size and thickness as well as becoming more sophisticated. Batteries applied to them have been required to be smaller, thinner and have higher energy densities. As a result, the demand for flat-shaped lithium ion secondary batteries is increasing. The recent trend of portable electronic devices is to reduce the thickness rather than reduce the size, and it is easy to put them in pockets and bags, and it does not impair ease of use.
[0003]
In order to achieve the reduction in the thickness of the device, it is required to reduce the thickness of the battery, which is the power source of the device. Since the battery case is formed by drawing or handling, the smaller the opening area with respect to the depth in the processing direction, the more difficult the processing becomes, and the more difficult it is to insert the electrode plate group into the battery case. In order to further reduce the thickness of the current flat prismatic battery, it is necessary to fundamentally change the structure of the battery case.The battery case is formed in a half-shell, and after the electrode group is housed, the flat plate or A battery structure in which a battery case is closed by a half-shell lid has been developed.
[0004]
For example, in a battery disclosed in Japanese Patent Application Laid-Open No. 9-213286, a group of electrodes is accommodated in a container formed in a half-shell, a cover plate is arranged at an opening of the container, and the periphery of the cover plate is a container. The inside of the container is sealed by laser welding. Such a structure in which a large opening of a half-shell battery case is sealed with a flat plate is also disclosed in JP-A-2001-52658, and a battery is formed at an opening end of a battery case formed in a half-shell. The battery case is formed by forming a step portion where the lid fits, accommodating the electrode plate group in the battery case, fitting the battery lid into the step portion, and laser-welding the battery cover and the battery case around the battery cover. The inside is sealed.
[0005]
Further, the battery disclosed in Japanese Patent Application Laid-Open No. 2001-167744 has a configuration in which a group of electrode plates is accommodated in a concave portion of a pair of half-shell members provided with a flange portion, and the two members are welded at the flange portion. The space between the two members accommodating the electrode plate group is sealed.
[0006]
[Problems to be solved by the invention]
In each of the above prior arts, laser welding is used for the step of welding the peripheral portion of the lid to the periphery of the half shell to seal the concave portion accommodating the electrode group of the battery case. Laser welding has high equipment costs and it is difficult to select the laser power.If the power is weak, it takes a long time to melt due to low heat absorption due to reflection, and if the power is increased, it will be rapidly heated and will melt. Objects are scattered and pinholes and cracks are likely to occur.
[0007]
Also, the portion to be laser-welded is made at the edge where the battery case and the lid are abutted to reduce the thermal effect on the electrode group, but the gap between the battery case and the lid is filled with a molten material. Therefore, there is a problem that dents are easily generated after welding, and the occurrence of dents tends to lower the welding strength.
[0008]
An object of the present invention is to provide a battery capable of forming a thin battery at low cost by improving a welding method in which a battery case accommodating an electrode plate group is closed with a lid, and a method of manufacturing the battery.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a battery according to the first invention of the present application has a battery case formed in a half-shell body obtained by processing a metal plate and providing a flange around an opening of a concave portion, and accommodating an electrode plate group in the concave portion. The metal cover plate, which is disposed with the peripheral portion overlapping the flange, and the flange are joined by seam welding.
[0010]
According to the above configuration, the battery case can be easily processed, and the electrode plate group can be easily accommodated. Since the sealing of the battery case is performed by seam welding that can continuously form the welding of the lid plate in a linear manner while rotating the disk electrode, the processing cost can be reduced and the electrode group is not adversely affected. It can be sealed.
[0011]
In each of the above configurations, a step portion with a reduced depth is formed at the end of the concave portion, and the outside of the positive electrode and the negative electrode connected to the positive electrode plate and the negative electrode plate forming the electrode plate group and exposed to the outside at the step portion, respectively. When the connection terminal is provided, external connection can be performed within the thickness range of the battery, and battery connection can be easily performed with a small and thin device.
[0012]
Further, in the battery manufacturing method according to the second aspect of the present invention, the metal plate is press-processed, and the concave portion, a welding margin provided in a flange shape around the concave portion, and an opening communicating from the inside of the concave portion to the outside are provided. A battery case is formed in the half shell, an external connection terminal is attached to the opening via a gasket, the opening is sealed, and the electrode plate group connected to the external connection terminal is accommodated in the battery case. A cover plate is arranged on the open side of the case, and the inside of the battery case is sealed by seam welding between the periphery of the cover plate and the welding margin, and the inside of the battery case is inserted from an inlet formed at an arbitrary position of the battery case. , And the inlet is closed with a stopper.
[0013]
According to the above manufacturing method, the battery case housing the electrode group and the lid plate are joined by seam welding in which the welding is linearly formed while rotating the disk electrode, so that the melting by laser welding is performed. Unlike bonding, the heat effect on the electrode group during welding is small and there is no generation of minute gaps (cracks), so there is no reduction in sealing performance, and the battery case can be sealed with an inexpensive device configuration It is.
[0014]
In the above-mentioned manufacturing method, by forming continuously a protruding portion protruding toward the opposing counterpart on the lid plate or the welding margin, so that the seam welding is performed in consideration of the projection welding, the joining is further improved. It can be implemented reliably.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings to facilitate understanding of the present invention. The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.
[0016]
FIG. 1 shows an external shape of a battery 1 according to the present embodiment, which is configured as a flat rectangular lithium ion secondary battery. As shown in FIG. 2, the battery 1 accommodates an electrode plate group 4 in a battery case 2 formed in a half-shell body and disposes an open portion of the battery case 2 with a cover plate 3. It is configured to be sealed. The material of the metal plates of the battery case 2 and the cover plate 3 is not particularly limited, and nickel-plated steel plate, stainless steel, and aluminum alloy can be used, and the thickness thereof is preferably 0.4 mm or less. It is preferable that the battery case 2 and the cover plate 3 be made of the same material from the viewpoints of seam welding easiness and reliability.
[0017]
As shown in FIG. 2, the battery case 2 is formed by pressing a metal plate to form a concave portion 5 having a stepped portion 6 and providing a welding margin 8 in a flange shape around the concave portion 5. The stepped portion 6 is a portion for forming external connection terminals of the positive electrode and the negative electrode. In this case, the terminal hole 7 formed in the stepped portion 6 is insulated from the battery case 2 by an outer gasket 11 and an inner gasket 12 and ensures airtightness. Then, the rivet 10 serving as the positive electrode external connection terminal is fastened and fixed. Further, an injection port 14 for the electrolyte is formed in the step portion 6.
[0018]
An electrode group 4 in which a positive electrode plate and a negative electrode plate are wound via a separator is accommodated in the concave portion 5 of the battery case 2. A positive electrode lead 15 pulled out of the positive electrode plate of the electrode plate group 4 shown in FIG. 2 is joined to the rivet 10, and a negative electrode lead 16 pulled out of the negative electrode plate is joined on the step 6. The configuration of the electrode plate group 4 may be such that the winding direction of the positive electrode plate and the negative electrode plate is the longitudinal direction, as shown in FIG. The electrode plate group 4a shown in FIG. 4 is configured such that a positive electrode plate and a negative electrode plate are wound in the longitudinal direction with a separator interposed therebetween, a positive electrode lead 15 is pulled out from a terminal end (winding end) of the positive electrode plate, and a negative electrode lead 16 is connected to the negative electrode plate. Pulled out from the terminal end (winding end), the positive electrode lead 15 can be easily joined to the rivet 10 and the negative electrode lead 16 can be easily joined to the stepped portion 6, and the joining reliability can be improved.
[0019]
A cover plate 3 is put on the open portion of the battery case 2 that accommodates the electrode plate group 4, and the peripheral portion of the cover plate 3 and the welding margin 8 are seam-welded, so that the concave portion 5 of the battery case 5 is formed. Is sealed by the cover plate 3. In the seam welding, as is well known, welding is continuously formed in a linear manner while rotating a disk electrode, and a nugget in which a contact surface between a welding margin 8 and a cover plate 3 is molten is continuously formed. Therefore, the inside of the concave portion 5 is sealed.
[0020]
As shown in FIG. 3, when the projection (projection) 24 is formed linearly on the welding margin 8 or the welding line of the cover plate 3, the projection 24 and the contact portion thereof are accompanied by intensive resistance heat generation, When it is melted, it is crushed by the pressing force, so that reliable welding in which projection welding is added to seam welding is performed.
[0021]
A predetermined amount of electrolyte is injected into the sealed recess 5 from the electrolyte injection port 14, and after the injection is completed, a plug 13 is inserted into the electrolyte injection port 14, and the plug 13 is inserted into the step. The inside of the concave portion 5 is sealed by welding.
[0022]
The battery 1 manufactured according to the above manufacturing procedure has a rivet 10 formed on the stepped portion 6 as a positive external connection terminal as shown in FIG. 1 and a surface of the stepped portion 6 as a negative external connection terminal for external connection. Can be offered. Since the external connection terminals of the positive electrode and the negative electrode are formed on the stepped portion 6, the leads connected to the external connection terminals can be processed within the thickness of the battery 1. Further, even when the battery 1 is contact-connected to the external connection terminal, the contact structure can be formed within the thickness of the battery 1. Therefore, the battery 1 can be mounted on a device without impairing the characteristics of the thin battery 1.
[0023]
【The invention's effect】
As described above, according to the present invention, the structure of the battery container accommodating the power generation element is sealed by seam welding a metal lid to an open portion of a battery case obtained by processing a metal plate into a half shell. Because of this structure, the equipment cost and processing cost can be reduced, and the battery can be made thin. Also, since the external connection terminal is formed on the step portion thinner than the thickness of the battery, the connection process can be performed within the thickness of the battery, and the connection structure can be provided without impairing the characteristics of the thin battery. it can.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the external shape of a battery according to an embodiment.
FIG. 2 is an exploded perspective view showing each component of the battery.
FIG. 3 is a partial cross-sectional view showing a configuration provided with a projection.
FIG. 4 is an exploded perspective view to which another configuration of the electrode group is applied.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 battery 2 battery case 3 cover plate 4, 4 a electrode plate group 5 concave portion 6 stepped portion 8 welding margin 10 rivet (external connection terminal)
11 outer gasket 12 inner gasket 13 sealing

Claims

A metal case is formed by processing a metal plate and forming a battery case in a half-shell body provided with a flange around the opening of the concave portion, accommodating an electrode plate group in the concave portion, and superposing a peripheral portion on the flange. A battery characterized in that a lid plate made of aluminum and a flange are joined by seam welding.

A step portion with a reduced depth is formed at the end of the concave portion, and external connection terminals of the positive electrode and the negative electrode which are connected to the positive electrode plate and the negative electrode plate constituting the electrode plate group and exposed to the outside are provided at the step portion. The battery according to claim 1, comprising:

3. The battery according to claim 1, wherein a positive electrode lead drawn from the positive electrode plate of the electrode plate group is provided at a terminal end of the positive electrode plate, and a negative electrode lead drawn from the negative electrode plate is provided at a terminal end of the negative electrode plate.

Pressing a metal plate to form a battery case in a half-shell body provided with a concave portion, a welding margin provided in a flange shape around the concave portion, and an opening communicating from the inside of the concave portion to the outside, and forming the battery case in the opening portion An external connection terminal is attached via a gasket to seal the opening, the electrode plate group connected to the external connection terminal is housed in a battery case, and a cover plate is arranged on the open side of the battery case. The inside of the battery case is sealed by seam welding between the periphery and the welding margin of the battery case, an electrolyte is injected into the battery case from an injection port formed at an arbitrary position of the battery case, and the injection port is sealed with a plug. A method for producing a battery, comprising closing the battery.

5. The method for manufacturing a battery according to claim 4, wherein a projecting portion projecting toward the opposing counterpart is continuously formed on the cover plate or the welding margin, and the seam welding is performed in consideration of the projection welding.