JP2021089857A

JP2021089857A - Secondary battery

Info

Publication number: JP2021089857A
Application number: JP2019219876A
Authority: JP
Inventors: 草間　和幸; Kazuyuki Kusama; 和幸草間; 文彦石黒; Fumihiko Ishiguro
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2021-06-10
Anticipated expiration: 2039-12-04
Also published as: JP7236036B2

Abstract

【課題】二次電池の大容量化等を想定して活物質層が厚く形成された正負極シートを含む電極体を備えた二次電池を、安定的に供給すること。【解決手段】ここで開示される二次電池においては、正極シート３０の正極集電箔露出部分３６に絶縁層２１０が厚く設けられている。かかる絶縁層２１０は、捲回電極体の捲回軸方向の正極集電箔３２を集箔する側において、近接する負極シート４０の外方に至るまで設けられており、さらに、少なくとも正極シート３０ａの集電箔露出部分３６ａが集箔された状態では、線部Ｑにおいて、絶縁層２１０ａの端部と該端部に近接するセパレータ５０ａ，５０ｂおよび別の正極シート３０ｂとの間に隙間が無くなるように形成されている。【選択図】図４PROBLEM TO BE SOLVED: To stably supply a secondary battery provided with an electrode body including a positive / negative electrode sheet in which a thick active material layer is formed in anticipation of increasing the capacity of the secondary battery. In the secondary battery disclosed here, an insulating layer 210 is thickly provided on an exposed portion 36 of a positive electrode current collector foil of a positive electrode sheet 30. The insulating layer 210 is provided on the side where the positive electrode current collecting foil 32 in the winding axis direction of the wound electrode body is collected, up to the outside of the adjacent negative electrode sheet 40, and further, at least the positive electrode sheet 30a. In the state where the current collecting foil exposed portion 36a is collected, there is no gap between the end portion of the insulating layer 210a and the separators 50a and 50b close to the end portion and another positive electrode sheet 30b in the wire portion Q. It is formed like this. [Selection diagram] Fig. 4

Description

本発明は、二次電池に関する。詳しくは、正極および負極がセパレータを介在させつつ積層された積層構造を有する電極体を備える二次電池に関する。 The present invention relates to a secondary battery. More specifically, the present invention relates to a secondary battery including an electrode body having a laminated structure in which a positive electrode and a negative electrode are laminated with a separator interposed therebetween.

リチウムイオン二次電池（リチウム二次電池）、ナトリウムイオン二次電池等の非水電解質二次電池は、既存の電池に比べて軽量且つエネルギー密度が高いことから、近年、パソコンや携帯端末等のいわゆるポータブル電源や車両駆動用電池として用いられている。特に、軽量で高エネルギー密度が得られるリチウムイオン二次電池は、電気自動車（ＥＶ）、ハイブリッド自動車（ＨＶ）、プラグインハイブリッド自動車（ＰＨＶ）等の車両の駆動用高出力電源としても好ましく用いられている。 Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries (lithium secondary batteries) and sodium ion secondary batteries are lighter and have higher energy density than existing batteries. Therefore, in recent years, personal computers, mobile terminals, etc. have been used. It is used as a so-called portable power supply and a battery for driving a vehicle. In particular, a lithium ion secondary battery that is lightweight and has a high energy density is preferably used as a high-output power source for driving a vehicle such as an electric vehicle (EV), a hybrid vehicle (HV), or a plug-in hybrid vehicle (PHV). ing.

この種の二次電池の一形態としては、シート状の正極（以下、「正極シート」という場合がある。）および負極（以下、「負極シート」という場合がある。）が、セパレータを介在させつつ相互に複数回重なり合った正負極積層構造を有する電極体（以下、「積層構造電極体」という場合がある。）を備えるものが挙げられる。例えば、長尺な正極シートと同じく長尺な負極シートをセパレータを間に介在させつつ重ね合わせて長尺方向に捲回し、扁平に成形したいわゆる捲回型電極体は、かかる正負極積層構造を有する電極体の典型例である。あるいは、矩形状の正負極シートをセパレータを介在させつつ複正負交互に所定の枚数を重ね合わせて形成したいわゆる積層電極体もこの種の正負極積層構造を有する電極体である。
ここで、正極シートは、正極集電箔の一部に正極活物質層を塗布することで形成されたものであり、負極シートは、負極集電箔の一部に負極活物質層を塗布することで形成されたものである。また、正極シートにおける正極活物質層非形成部分（以下、「正極集電箔露出部分」ともいう。）と負極シートにおける負極活物質層形成部分とが対向する領域において内部短絡が生じることがないように、該正極シートの該領域に絶縁部材を設けることがある（特許文献１を参照）。 As one form of this type of secondary battery, a sheet-shaped positive electrode (hereinafter, may be referred to as a “positive electrode sheet”) and a negative electrode (hereinafter, may be referred to as a “negative electrode sheet”) interpose a separator. However, an electrode body having a positive / negative electrode laminated structure in which the positive and negative electrodes are laminated a plurality of times (hereinafter, may be referred to as a “laminated structure electrode body”) is provided. For example, a so-called wound electrode body formed by laminating a long negative electrode sheet like a long positive electrode sheet with a separator interposed therebetween and winding it in a long direction to form a flat electrode has such a positive and negative electrode laminated structure. This is a typical example of an electrode body having an electrode body. Alternatively, a so-called laminated electrode body formed by stacking a predetermined number of rectangular positive and negative electrode sheets alternately with a separator interposed therebetween is also an electrode body having this kind of positive and negative electrode laminated structure.
Here, the positive electrode sheet is formed by applying a positive electrode active material layer to a part of the positive electrode current collecting foil, and the negative electrode sheet is formed by applying the negative electrode active material layer to a part of the negative electrode current collecting foil. It was formed by that. Further, no internal short circuit occurs in the region where the positive electrode active material layer non-formed portion in the positive electrode sheet (hereinafter, also referred to as “positive electrode current collector foil exposed portion”) and the negative electrode active material layer formed portion in the negative electrode sheet face each other. As described above, an insulating member may be provided in the region of the positive electrode sheet (see Patent Document 1).

そして、かかる積層構造電極体には、所定の一の幅方向において、該電極体の本体部分（即ち、正負極の積層構造部分、換言すれば正負極活物質層形成部分が対向しつつ積層された部分をいう。）の一方の端部には、積層された正極シートそれぞれにおける正極集電箔露出部分が積層方向に複数重なり合うようにして存在しており、同様に、該本体部分の上記幅方向における他方の端部には、積層された負極シートそれぞれにおける負極活物質層非形成部分（以下、「負極集電箔露出部分」ともいう。）が積層方向に複数重なり合うようにして存在している。そして、かかる集電箔露出部分を束ね（以下、「集箔」ともいう。）、対応する極の集電端子の一部を配置し、超音波溶接等の溶接手段により接合することで正負極それぞれの集電構造が形成されている。 Then, on the laminated structure electrode body, the main body portion of the electrode body (that is, the laminated structure portion of the positive and negative electrodes, in other words, the positive and negative electrode active material layer forming portions, is laminated while facing each other in a predetermined width direction. At one end of each of the laminated positive electrode sheets, a plurality of exposed positive electrode current collecting foil portions are present so as to overlap in the stacking direction, and similarly, the width of the main body portion is described above. At the other end in the direction, a plurality of negative electrode active material layer non-formed portions (hereinafter, also referred to as “negative electrode current collecting foil exposed portions”) in each of the laminated negative electrode sheets are present so as to overlap in the laminated direction. There is. Then, the exposed parts of the current collecting foil are bundled (hereinafter, also referred to as "foil collecting"), a part of the current collecting terminals of the corresponding poles is arranged, and the positive and negative electrodes are joined by welding means such as ultrasonic welding. Each current collecting structure is formed.

特開２０１９−００３７８９号公報Japanese Unexamined Patent Publication No. 2019-003789

ところで、二次電池の大容量化等を想定して活物質層が厚く形成された正負極シートを有する積層構造電極体（即ち、比較的厚く積層された正負極積層構造を構成する複数の正極シートのうち最外部に存在する正極シートの集箔角度が大きい電極体）を集箔する場合、該積層構造の最外部付近に存在する正極シートには、該積層構造の積層方向中央部（即ち、集箔位置に近い部分）に存在する正極シートよりも大きなテンションがかかり得る。そして、上記正極シートにより押圧されたセパレータが近接する負極の端部と大きく干渉することで該セパレータが損傷し得るため、上記電極体の正負極間で内部短絡が生じる虞があり、好ましくない。例えば、図６は、従来の正極集電箔積層部の集箔の態様を示す模式図であり、捲回電極体の捲回軸方向の正極集電箔１３２を集箔する側（以後、「集箔方向」ともいう。）において、正極シート１３０の正極集電箔露出部分１３６が負極シート１４０およびセパレータ１５０からはみ出た状態で積層された正極集電箔積層部１３５が存在する。そして、負極シート１４０の負極活物質層形成部分との内部短絡を防止するために、上記集箔方向において、正極シート１３０の正極集電箔露出部分１３６に絶縁層１１０が薄く形成されており、且つ、該絶縁層１１０の形成部位が近接する負極シート１４０の外方に至るまで伸びている。かかる絶縁層１１０を有する正極集電箔積層部１３５を積層方向のいずれかの部分に存在する集箔位置において集箔し、該正極集電箔積層部１３５と正極集電端子１３７とを超音波溶接装置のホーン１２０およびアンビル１２１で挟み込み、該ホーン１２０から該アンビル１２１方向に押し込み荷重をかけながら溶接を行うことで、正極集電構造が形成される。しかしながら、上記正極集電箔積層部１３５の集箔に際しては、該集電箔積層部１３５の最外部付近に存在する正極シート１３０ａに対して、該集電箔積層部１３５の積層方向中央部（即ち、集箔位置に近い部分）に存在する正極シートと比較して大きなテンションがかかり得るため、該正極シート１３０ａに押圧されたセパレータ１５０ａが近接する負極１４０ａの端部と大きく干渉する虞がある。これにより、上記セパレータ１５０ａが損傷することで電極体の正負極間で内部短絡が生じ得るため、好ましくない。なお、上述したように、特許文献１には、正極シートにおける上記領域に絶縁部材を設ける技術が開示されているが、かかる絶縁部材を最外部の集箔角度が大きい電極体の作製に活用する内容の開示はない。 By the way, assuming an increase in the capacity of a secondary battery or the like, a laminated structure electrode body having a positive / negative electrode sheet in which an active material layer is thickly formed (that is, a plurality of positive electrodes constituting a relatively thick laminated positive / negative electrode structure). When collecting foil (an electrode body having a large foil collecting angle of the positive electrode sheet existing on the outermost side of the sheet), the positive electrode sheet existing near the outermost part of the laminated structure has a central portion in the stacking direction of the laminated structure (that is, that is). , A portion closer to the foil collection position) may be subject to greater tension than the positive electrode sheet. Then, the separator pressed by the positive electrode sheet greatly interferes with the end of the adjacent negative electrode, so that the separator can be damaged, which may cause an internal short circuit between the positive and negative electrodes of the electrode body, which is not preferable. For example, FIG. 6 is a schematic view showing a mode of collecting foil in the conventional positive electrode current collecting foil laminated portion, and is a side for collecting the positive electrode current collecting foil 132 in the winding axis direction of the wound electrode body (hereinafter, “” In the "foil collecting direction"), there is a positive electrode current collecting foil laminated portion 135 in which the positive electrode current collecting foil exposed portion 136 of the positive electrode sheet 130 is laminated so as to protrude from the negative electrode sheet 140 and the separator 150. Then, in order to prevent an internal short circuit of the negative electrode sheet 140 with the negative electrode active material layer forming portion, the insulating layer 110 is thinly formed on the positive electrode current collecting foil exposed portion 136 of the positive electrode sheet 130 in the foil collecting direction. Moreover, the forming portion of the insulating layer 110 extends to the outside of the adjacent negative electrode sheet 140. The positive electrode current collecting foil laminated portion 135 having the insulating layer 110 is collected at a foil collecting position existing at any portion in the laminating direction, and the positive electrode current collecting foil laminated portion 135 and the positive electrode current collecting terminal 137 are ultrasonically bonded. A positive electrode current collecting structure is formed by sandwiching the horn 120 and the anvil 121 of the welding apparatus and performing welding while applying a pushing load from the horn 120 toward the anvil 121. However, when collecting the foil of the positive electrode current collecting foil laminated portion 135, the central portion of the current collecting foil laminated portion 135 in the stacking direction (the central portion of the current collecting foil laminated portion 135 with respect to the positive electrode sheet 130a existing near the outermost portion of the current collecting foil laminated portion 135. That is, since a large tension can be applied as compared with the positive electrode sheet existing in the portion near the foil collecting position), the separator 150a pressed against the positive electrode sheet 130a may greatly interfere with the end portion of the adjacent negative electrode 140a. .. As a result, damage to the separator 150a may cause an internal short circuit between the positive and negative electrodes of the electrode body, which is not preferable. As described above, Patent Document 1 discloses a technique of providing an insulating member in the above-mentioned region of the positive electrode sheet, and the insulating member is utilized for manufacturing the outermost electrode body having a large foil collecting angle. There is no disclosure of the contents.

本発明は、かかる事情に鑑みてなされたものであり、その目的は、二次電池の大容量化等を想定して活物質層が厚く形成された正負極シートを含む電極体を備えた二次電池を、安定的に供給することである。 The present invention has been made in view of such circumstances, and an object of the present invention is to include an electrode body including a positive and negative electrode sheets in which an active material layer is thickly formed in anticipation of increasing the capacity of a secondary battery. The next battery is to be supplied stably.

上記目的を実現するべく、本発明は、正極集電箔上に正極活物質層が形成されたシート状正極と、負極集電箔上に負極活物質層が形成されたシート状負極とが、セパレータを介在させつつ複数重なり合って構成された正負極積層構造を有する電極体を備える二次電池を提供する。ここで開示される二次電池の上記電極体における所定の一の幅方向の両端部のうちの一方の端部には、上記正極活物質層が形成されていない正極集電箔露出部分が負極からはみ出た状態で積層された正極集電箔積層部が存在し、且つ、該両端部のうちの他方の端部には、上記負極活物質層が形成されていない負極集電箔露出部分が正極からはみ出た状態で積層された負極集電箔積層部が存在し、上記正負極集電箔積層部のうち少なくとも正極集電箔積層部において、積層方向のいずれかの部分に各集電箔露出部分が集箔される集箔位置が存在し、該集箔位置において集箔された該集電箔露出部分は対応する正極集電端子と接合されており、上記正極集電箔積層部のうち上記集箔位置から最も遠い位置にある正極シートの集電箔露出部分が集箔される際の集箔角度が３０°以上であり、上記幅方向における上記正極集電箔積層部が集箔される側において、上記正極シートの集電箔露出部分に絶縁層が形成されており、且つ、該絶縁層の形成部位は近接する上記負極の外方に至るまで上記幅方向に延びており、ここで、上記絶縁層は少なくとも上記最も遠い位置にある正極シートの集電箔露出部分が集箔された状態において、該絶縁層の端部と該端部に近接するセパレータおよび別の正極シートとの間に隙間が無くなるように形成されることを特徴とする。 In order to realize the above object, the present invention comprises a sheet-shaped positive electrode in which a positive electrode active material layer is formed on a positive electrode current collecting foil, and a sheet-shaped negative electrode in which a negative electrode active material layer is formed on a negative electrode current collecting foil. Provided is a secondary battery including an electrode body having a positive and negative electrode laminated structure configured by overlapping a plurality of layers with a separator interposed therebetween. At one end of both ends in a predetermined width direction of the electrode body of the secondary battery disclosed here, a positive electrode current collecting foil exposed portion on which the positive electrode active material layer is not formed is a negative electrode. There is a positive electrode current collecting foil laminated portion laminated in a state of protruding from the above, and at the other end of the both end portions, a negative electrode current collecting foil exposed portion on which the negative electrode active material layer is not formed is formed. There is a negative electrode current collecting foil laminated portion that is laminated so as to protrude from the positive electrode, and among the positive and negative electrode current collecting foil laminated portions, at least the positive electrode current collecting foil laminated portion, each current collecting foil is located in any part in the stacking direction. There is a foil collection position where the exposed portion is collected, and the current collection foil exposed portion collected at the foil collection position is joined to the corresponding positive electrode current collection terminal, and the positive electrode current collection foil laminated portion The foil collection angle when the exposed portion of the positive electrode sheet, which is the farthest from the foil collection position, is collected is 30 ° or more, and the positive electrode current collection foil laminated portion in the width direction collects foil. An insulating layer is formed on the exposed portion of the current collecting foil of the positive electrode sheet, and the formed portion of the insulating layer extends in the width direction to the outside of the adjacent negative electrode. Here, the insulating layer includes an end portion of the insulating layer, a separator close to the end portion, and another positive electrode sheet in a state where the exposed portion of the current collecting foil of the positive electrode sheet located at least at the farthest position is collected. It is characterized in that it is formed so that there is no gap between the two.

かかる構成の二次電池においては、正極集電箔積層部のうち集箔位置から最も遠い位置に存在する正極シートの集電箔露出部分が集箔される際の集箔角度が緩和され得るため、該正極シートに対して（該集箔位置に近い部分に存在する正極シートと比較して）大きなテンションがかかりにくくなる。これにより、上記正極シートにより押圧されたセパレータと近接する負極の端部との干渉が弱くなることで、該セパレータが損傷する可能性が低減されるため、電極体の正負極間での内部短絡が生じにくくなる。 In the secondary battery having such a configuration, the foil collection angle when the exposed portion of the positive electrode collecting foil of the positive electrode sheet existing at the position farthest from the foil collecting position in the positive electrode current collecting foil laminated portion is collected can be relaxed. , It becomes difficult to apply a large tension to the positive electrode sheet (compared to the positive electrode sheet existing in the portion near the foil collecting position). As a result, the interference between the separator pressed by the positive electrode sheet and the end portion of the adjacent negative electrode is weakened, so that the possibility of damage to the separator is reduced, and thus an internal short circuit between the positive and negative electrodes of the electrode body is reduced. Is less likely to occur.

本実施形態に係る角型形状のリチウムイオン二次電池の外形を模式的に示す斜視図である。It is a perspective view which shows typically the outer shape of the square-shaped lithium ion secondary battery which concerns on this embodiment. 図１におけるII−II線断面図である。FIG. 2 is a sectional view taken along line II-II in FIG. 本実施形態に係る捲回電極体の構成を模式的に示す斜視図である。It is a perspective view which shows typically the structure of the winding electrode body which concerns on this embodiment. 本実施形態に係る正極集電箔積層部の集箔の態様を示す模式図である。It is a schematic diagram which shows the mode of the foil collection of the positive electrode current collector foil laminated part which concerns on this embodiment. 図４における正極シートの集電箔露出部分に形成される絶縁層を示す模式図である。It is a schematic diagram which shows the insulating layer formed in the current collector foil exposed part of the positive electrode sheet in FIG. 従来の正極集電箔積層部の集箔の態様を示す模式図である。It is a schematic diagram which shows the mode of the foil collection of the conventional positive electrode current collector foil laminated part.

以下、適宜図面を参照しながら、本発明の好適な実施形態ついて説明する。なお、本明細書において特に言及している事項以外の事柄であって本発明の実施に必要な事柄（例えば、本発明を特徴付けない電池の一般的な製造プロセス等）は、当該分野における従来技術に基づく当業者の設計事項として把握され得る。本発明は、本明細書に開示されている内容と当該分野における技術常識とに基づいて実施することができる。なお、以下の図面において、同じ作用を奏する部材・部位に同じ符号を付して説明し、重複する説明は省略または簡略化することがある。また、各図における寸法関係（長さ、幅、厚さ等）は必ずしも実際の寸法関係を反映するものではない。 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned in the present specification and necessary for carrying out the present invention (for example, general manufacturing processes of batteries that do not characterize the present invention) are conventionally used in the art. It can be grasped as a design matter of a person skilled in the art based on technology. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art. In the following drawings, members / parts having the same function may be described with the same reference numerals, and duplicate description may be omitted or simplified. Further, the dimensional relationship (length, width, thickness, etc.) in each drawing does not necessarily reflect the actual dimensional relationship.

また、以下の実施形態においては、二次電池として捲回電極体を備えるリチウムイオン二次電池を例にして詳細に説明するが、本発明をかかる実施形態に限定することを意図したものではない。例えば、正極シートと負極シートとがセパレータを介在させつつ相互に複数重なり合った積層構造を有する積層電極体等も好適に使用され得る。 Further, in the following embodiments, a lithium ion secondary battery including a wound electrode body as a secondary battery will be described in detail as an example, but the present invention is not intended to be limited to such embodiments. .. For example, a laminated electrode body or the like having a laminated structure in which a positive electrode sheet and a negative electrode sheet are laminated on each other while interposing a separator can be preferably used.

図１は、本実施形態に係る角型形状のリチウムイオン二次電池の外形を模式的に示す斜視図であり、図２は、図１中のII−II線断面図である。また、図３は、本実施形態に係る捲回電極体の構成を模式的に示す斜視図である。なお、これ以降に記載の「幅方向」とは、特に断りのない限り、捲回電極体の捲回軸方向を示すものとする。
図１および図２に示されるように、本実施形態に係るリチウムイオン二次電池１００は、直方体形状の角型の電池ケース１０と、該ケース１０の開口部１２を塞ぐ蓋体１４とを備える。また、電池ケース１０の内部には、上記開口部１２より収容された扁平形状の捲回電極体２０および電解質が配置されている。そして、上記蓋体１４には、外部接続用の外部正極集電端子３８と外部負極集電端子４８とが設けられており、外部集電端子３８、４８の一部はケース内部で正極集電端子３７または負極集電端子４７にそれぞれ接続されている。 FIG. 1 is a perspective view schematically showing the outer shape of a square-shaped lithium ion secondary battery according to the present embodiment, and FIG. 2 is a sectional view taken along line II-II in FIG. Further, FIG. 3 is a perspective view schematically showing the configuration of the wound electrode body according to the present embodiment. The "width direction" described below shall indicate the winding axis direction of the wound electrode body unless otherwise specified.
As shown in FIGS. 1 and 2, the lithium ion secondary battery 100 according to the present embodiment includes a rectangular parallelepiped square battery case 10 and a lid 14 that closes the opening 12 of the case 10. .. Further, inside the battery case 10, a flat wound electrode body 20 and an electrolyte housed through the opening 12 are arranged. The lid 14 is provided with an external positive electrode current collecting terminal 38 and an external negative electrode current collecting terminal 48 for external connection, and a part of the external current collecting terminals 38 and 48 is positive electrode current collecting inside the case. It is connected to the terminal 37 or the negative electrode current collector terminal 47, respectively.

次に、図２および図３を参照しながら、本実施形態に係る捲回電極体２０について説明する。図２に示されるように、捲回電極体２０は、長尺状の正極集電箔３２の表面に正極活物質層３４を有する正極シート３０、長尺シート状のセパレータ５０、長尺状の負極集電箔４２の表面に負極活物質層４４を有する負極シート４０から構成される。そして、図３に示されるように、捲回軸方向の方向での断面視において、正極シート３０及び負極シート４０は２枚のセパレータ５０を介して積層されており、正極シート３０、セパレータ５０、負極シート４０、セパレータ５０の順に積層されている。かかる積層物は、軸芯（図示しない）の周囲に筒状に捲回され、得られた捲回電極体２０を側面方向から押しつぶして拉げさせることによって扁平形状に成形されている。 Next, the wound electrode body 20 according to the present embodiment will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, the wound electrode body 20 includes a positive electrode sheet 30 having a positive electrode active material layer 34 on the surface of a long positive electrode current collecting foil 32, a long sheet-shaped separator 50, and a long-shaped positive electrode body 20. It is composed of a negative electrode sheet 40 having a negative electrode active material layer 44 on the surface of the negative electrode current collecting foil 42. Then, as shown in FIG. 3, in the cross-sectional view in the direction of the winding axis, the positive electrode sheet 30 and the negative electrode sheet 40 are laminated via the two separators 50, and the positive electrode sheet 30, the separator 50, and the like. The negative electrode sheet 40 and the separator 50 are laminated in this order. Such a laminate is wound in a tubular shape around a shaft core (not shown), and the obtained wound electrode body 20 is crushed from the side surface direction and squeezed to form a flat shape.

また、図３に示されるように、本実施形態に係る捲回電極体２０は、その捲回軸方向の中心部に、正極集電箔３２の表面上に形成された正極活物質層３４と、負極集電箔４２の表面上に形成された負極活物質層４４とが重なり合って密に積層された部分を有する。また、上記捲回軸方向の一方の端部においては、正極活物質層３４が形成されずに正極集電箔３２が露出した部分（正極集電箔露出部分３６）がセパレータ５０および負極シート４０（あるいは、正極活物質層３４と負極活物質層４４との密な積層部分）からはみ出た状態で積層されている。即ち、上記電極体２０の端部には、正極集電箔露出部分３６が積層することで形成される正極集電箔積層部３５が存在する。また、電極体２０の他方の端部も同様に、負極集電箔露出部分４６が積層することで形成される負極集電箔積層部４５が存在する。なお、ここで開示される技術が好適に適用され得る対象となる電極体は、正極集電箔積層部における集箔位置から最も遠い位置に存在する正極シートの集電箔露出部分が集箔される際の集箔角度が３０°以上のものである。また、上記集箔角度は、４０°以上、５０°以上であり得る。なお、本実施形態に係る正負極の電極活物質、セパレータ、電解質、非水電解液等の構成は特に限定されず、従来公知のリチウムイオン二次電池に使用し得るものを好適に使用し得る。本発明は、正極集電箔積層部の集箔に関するものであるため、詳細の説明は割愛する。 Further, as shown in FIG. 3, the wound electrode body 20 according to the present embodiment has a positive electrode active material layer 34 formed on the surface of the positive electrode current collecting foil 32 at the center in the winding axis direction. It has a portion in which the negative electrode active material layer 44 formed on the surface of the negative electrode current collecting foil 42 is overlapped and densely laminated. Further, at one end in the winding axis direction, the portion where the positive electrode current collecting foil 32 is exposed without forming the positive electrode active material layer 34 (the positive electrode current collecting foil exposed portion 36) is the separator 50 and the negative electrode sheet 40. (Alternatively, the positive electrode active material layer 34 and the negative electrode active material layer 44 are laminated so as to protrude from the densely laminated portion). That is, at the end of the electrode body 20, there is a positive electrode current collector foil laminated portion 35 formed by laminating the positive electrode current collecting foil exposed portion 36. Similarly, the other end portion of the electrode body 20 also has a negative electrode current collecting foil laminated portion 45 formed by laminating the negative electrode current collecting foil exposed portion 46. In the electrode body to which the technique disclosed here can be preferably applied, the exposed portion of the current collecting foil of the positive electrode sheet existing at the position farthest from the foil collecting position in the positive electrode current collecting foil laminated portion is collected. The foil collection angle is 30 ° or more. Further, the foil collection angle may be 40 ° or more and 50 ° or more. The configurations of the positive and negative electrode active materials, separators, electrolytes, non-aqueous electrolytes, etc. according to the present embodiment are not particularly limited, and those that can be used in conventionally known lithium ion secondary batteries can be preferably used. .. Since the present invention relates to the foil collection of the positive electrode current collector foil laminated portion, detailed description thereof will be omitted.

続いて、図４および図５を参照しながら、本実施形態に係る正極集電箔積層部の集箔の態様について説明する。なお、図４および図５における絶縁層としては、絶縁性と、好ましくは耐熱性を有するものがよく、例えば、シリカやアルミナ等の無機フィラーが好適に使用され得る。 Subsequently, the mode of collecting the foil of the positive electrode current collecting foil laminated portion according to the present embodiment will be described with reference to FIGS. 4 and 5. The insulating layer in FIGS. 4 and 5 is preferably one having insulating properties and preferably heat resistance, and for example, an inorganic filler such as silica or alumina can be preferably used.

図４は、本実施形態に係る正極集電箔積層部の集箔の態様を示す模式図であり、図５は、図４における正極シートの集電箔露出部分に形成される絶縁層を示す模式図である。なお、以後の説明においては、幅方向のうち正極集電箔積層部３５が集箔される側のことを「集箔方向」と表記する。
図４に示されるように、集箔方向において正極シート３０の正極集電箔露出部分３６が負極シート４０およびセパレータ５０からはみ出た状態で積層された正極集電箔積層部３５が存在する。そして、負極シート４０の負極活物質層形成部分との内部短絡を防止するために、上記集箔方向において、正極シート３０の正極集電箔露出部分３６に絶縁層２１０が厚く形成されており、且つ、該絶縁層２１０の形成部位が近接する負極シート４０の外方に至るまで伸びている。かかる絶縁層２１０を有する正極集電箔積層部３５を積層方向のいずれかの部分に存在する集箔位置において集箔し、該正極集電箔積層部３５と正極集電端子３７とを超音波溶接装置のホーン２２０およびアンビル２２１で挟み込み、該ホーン２２０から該アンビル２２１方向に押し込み荷重をかけながら溶接を行うことで、正極集電構造が形成される。ここで、本実施形態に係る絶縁層２１０ａは、少なくとも正極シート３０ａの集電箔露出部分３６ａが集箔された状態では、図４中の線部Ｑにおいて、該絶縁層２１０ａの端部と該端部に近接するセパレータ５０ａ，５０ｂおよび別の正極シート３０ｂの間に隙間が無くなるように形成されることを特徴とする（前述した図６に示す正極集電箔積層部の集箔では、図６中の線部Ｐにおいて、絶縁層１１０ａの端部と該端部に近接するセパレータ１５０ａ，１５０ｂおよび別の正極シート１３０ｂとの間に隙間が生じていた）。この場合、上記正極集電箔積層部３５の集箔に際して、該正極集電箔積層部３５のうち集箔位置から最も遠い位置に存在する正極シート３０ａの正極集電箔露出部分３６ａが集箔される際の集箔角度が緩和され得るため、該正極シート３０ａに対して（上記集箔位置に近い部分に存在する正極シートと比較して）大きなテンションがかかりにくくなる。これにより、上記正極シート３０ａにより押圧されたセパレータ５０ａと近接する負極４０ａの端部との干渉が弱くなることで、該セパレータ５０ａが損傷する可能性が低減され得るため、電極体２０の正負極間で内部短絡が生じにくくなり、信頼性の高い二次電池を得ることが可能になる。 FIG. 4 is a schematic view showing a mode of collecting foil of the positive electrode current collecting foil laminated portion according to the present embodiment, and FIG. 5 shows an insulating layer formed on an exposed portion of the current collecting foil of the positive electrode sheet in FIG. It is a schematic diagram. In the following description, the side in the width direction in which the positive electrode current collector foil laminated portion 35 is collected is referred to as the “foil collection direction”.
As shown in FIG. 4, there is a positive electrode current collecting foil laminated portion 35 in which the positive electrode current collecting foil exposed portion 36 of the positive electrode sheet 30 is laminated so as to protrude from the negative electrode sheet 40 and the separator 50 in the foil collecting direction. Then, in order to prevent an internal short circuit of the negative electrode sheet 40 with the negative electrode active material layer forming portion, the insulating layer 210 is thickly formed on the positive electrode current collecting foil exposed portion 36 of the positive electrode sheet 30 in the foil collecting direction. Moreover, the forming portion of the insulating layer 210 extends to the outside of the adjacent negative electrode sheet 40. The positive electrode current collecting foil laminated portion 35 having the insulating layer 210 is collected at a foil collecting position existing at any portion in the laminating direction, and the positive electrode current collecting foil laminated portion 35 and the positive electrode current collecting terminal 37 are ultrasonically bonded. A positive electrode current collecting structure is formed by sandwiching the horn 220 and the anvil 221 of the welding apparatus and performing welding while applying a pushing load from the horn 220 in the direction of the anvil 221. Here, in the insulating layer 210a according to the present embodiment, at least in a state where the current collecting foil exposed portion 36a of the positive electrode sheet 30a is collected, the end portion of the insulating layer 210a and the insulating layer 210a are shown in the line portion Q in FIG. It is characterized in that it is formed so that there is no gap between the separators 50a and 50b close to the end portion and another positive electrode sheet 30b (in the foil collection of the positive electrode current collector foil laminated portion shown in FIG. 6 described above, FIG. In the wire portion P in 6, a gap was formed between the end portion of the insulating layer 110a and the separators 150a and 150b adjacent to the end portion and another positive electrode sheet 130b). In this case, when collecting the foil of the positive electrode current collecting foil laminated portion 35, the positive electrode current collecting foil exposed portion 36a of the positive electrode sheet 30a existing at the position farthest from the foil collecting position in the positive electrode current collecting foil laminated portion 35 collects foil. Since the foil collecting angle at the time of collecting the foil can be relaxed, a large tension is less likely to be applied to the positive electrode sheet 30a (compared to the positive electrode sheet existing in the portion close to the foil collecting position). As a result, the interference between the separator 50a pressed by the positive electrode sheet 30a and the end of the negative electrode 40a in the vicinity can be weakened, so that the possibility of damage to the separator 50a can be reduced. Therefore, the positive and negative electrodes of the electrode body 20 can be reduced. Internal short circuits are less likely to occur between them, making it possible to obtain a highly reliable secondary battery.

以上、本発明の好適な実施形態について図面を参照しつつ説明したが、より好適な絶縁層２１０としては、該絶縁層２１０の厚みが例えば２０μｍ以下（５〜１８μｍ）であり、また、図５に示されるように、上記幅方向（即ち、捲回軸方向）において、正極シート３０の正極集電箔露出部分３６と負極シート４０の負極活物質層形成部分とが対向する部分の長さをＡ１、絶縁層２１０の長さをＡ２とすると、Ａ２／Ａ１≧１．３であるものが好ましく使用され得る。 The preferred embodiment of the present invention has been described above with reference to the drawings, but as a more suitable insulating layer 210, the thickness of the insulating layer 210 is, for example, 20 μm or less (5 to 18 μm), and FIG. As shown in the above, the length of the portion where the positive electrode current collecting foil exposed portion 36 of the positive electrode sheet 30 and the negative electrode active material layer forming portion of the negative electrode sheet 40 face each other in the above width direction (that is, the winding axis direction). Assuming that the lengths of A1 and the insulating layer 210 are A2, those having A2 / A1 ≧ 1.3 can be preferably used.

以上、本発明をいくつかの好適な実施形態により説明してきたが、こうした記述は限定事項ではなく、勿論、種々の改変が可能である。例えば、電池の種類は上述したリチウムイオン二次電池に限られず、電極体構成材料や電解質が異なる種々の内容の電池、例えばニッケル水素電池、ニッケルカドミウム電池、或いは電気二重層キャパシタのようないわゆる物理電池であってもよい。また、電解質の種類も、上述した非水電解液に限定されず、水系電解液や、固体又はゲル状の電解質等であってもよい。 Although the present invention has been described above with some preferred embodiments, such a description is not a limitation and, of course, various modifications can be made. For example, the type of battery is not limited to the above-mentioned lithium ion secondary battery, and batteries having various contents having different electrode body constituent materials and electrolytes, for example, a nickel hydrogen battery, a nickel cadmium battery, or a so-called physical such as an electric double layer capacitor. It may be a battery. Further, the type of the electrolyte is not limited to the above-mentioned non-aqueous electrolyte solution, and may be an aqueous electrolyte solution, a solid or gel-like electrolyte, or the like.

ここに開示される電池によると、上述のとおり、信頼性の高い電池（例えばリチウムイオン二次電池）を提供することができる。したがって、ここに開示される電池は、例えば、自動車等の車両に搭載される駆動用電源として好適に用いることができる。特にプラグインハイブリッド自動車（ＰＨＶ）、ハイブリッド自動車（ＨＶ）、電気自動車（ＥＶ）、等の駆動用電源として好適である。また、本発明によれば、ここに開示される電池（例えばリチウムイオン二次電池）を、好ましくは動力源（典型的には複数個の二次電池が相互に電気的に接続されてなる組電池）として備えた車両が提供される。 According to the batteries disclosed herein, as described above, a highly reliable battery (for example, a lithium ion secondary battery) can be provided. Therefore, the battery disclosed herein can be suitably used as a driving power source mounted on a vehicle such as an automobile, for example. In particular, it is suitable as a driving power source for plug-in hybrid vehicles (PHVs), hybrid vehicles (HVs), electric vehicles (EVs), and the like. Further, according to the present invention, the battery disclosed herein (for example, a lithium ion secondary battery) is preferably a set in which a power source (typically, a plurality of secondary batteries are electrically connected to each other). A vehicle equipped as a battery) is provided.

１０電池ケース
１２開口部
１４蓋体
２０捲回電極体
３０，３０ａ，３０ｂ正極シート（正極）
３２正極集電箔
３４正極活物質層
３５正極集電箔積層部
３６，３６ａ正極集電箔露出部分
３７正極集電端子
３８外部正極集電端子
４０，４０ａ負極シート（負極）
４２負極集電箔
４４負極活物質層
４５負極集電箔積層部
４６負極集電箔露出部分
４７負極集電端子
４８外部負極集電端子
５０，５０ａ，５０ｂセパレータ
１００リチウムイオン二次電池
１１０，１１０ａ絶縁層
１２０ホーン
１２１アンビル
１３０，１３０ａ，１３０ｂ正極シート（正極）
１３２正極集電箔
１３５正極集電箔積層部
１３６正極集電箔露出部分
１３７正極集電端子
１４０，１４０ａ負極シート（負極）
１５０，１５０ａ，１５０ｂセパレータ
２１０，２１０ａ絶縁層
２２０ホーン
２２１アンビル
Ｐ，Ｑ線部

10 Battery case 12 Opening 14 Lid body 20 Winding electrode bodies 30, 30a, 30b Positive electrode sheet (positive electrode)
32 Positive electrode current collecting foil 34 Positive electrode active material layer 35 Positive electrode current collecting foil laminated portion 36, 36a Positive electrode current collecting foil exposed portion 37 Positive electrode current collecting terminal 38 External positive electrode current collecting terminal 40, 40a Negative electrode sheet (negative electrode)
42 Negative electrode current collecting foil 44 Negative electrode active material layer 45 Negative electrode current collecting foil laminated part 46 Negative electrode current collecting foil exposed part 47 Negative electrode current collecting terminal 48 External negative electrode current collecting terminal 50, 50a, 50b Separator 100 Lithium ion secondary battery 110, 110a Insulation layer 120 Horn 121 Anvil 130, 130a, 130b Positive electrode sheet (positive electrode)
132 Positive electrode current collector foil 135 Positive electrode current collector foil laminated portion 136 Positive electrode current collector foil exposed portion 137 Positive electrode current collector terminal 140, 140a Negative electrode sheet (negative electrode)
150, 150a, 150b Separator 210, 210a Insulation layer 220 Horn 221 Anvil P, Q line

Claims

A sheet-shaped positive electrode having a positive electrode active material layer formed on a positive electrode current collecting foil and a sheet-shaped negative electrode having a negative electrode active material layer formed on a negative electrode current collecting foil were formed by overlapping a plurality of sheets with a separator interposed therebetween. A secondary battery including an electrode body having a positive and negative electrode laminated structure.
A positive electrode in which a positive electrode current collecting foil exposed portion on which the positive electrode active material layer is not formed is laminated so as to protrude from the negative electrode at one end of both ends in a predetermined width direction of the electrode body. The negative electrode current collecting foil laminated portion is present, and the negative electrode current collecting foil exposed portion on which the negative electrode active material layer is not formed is laminated on the other end of both ends in a state of protruding from the positive electrode. There is a negative electrode current collector foil laminated part,
Among the positive and negative electrode current collecting foil laminated portions, at least in the positive electrode current collecting foil laminated portion, there is a foil collecting position where each current collecting foil exposed portion is collected in any part in the laminating direction, and at the foil collecting position. The exposed part of the collected foil is joined to the corresponding positive electrode current collecting terminal.
Among the positive electrode current collector foil laminated portions, the foil collection angle when the current collector foil exposed portion of the positive electrode sheet located at the position farthest from the foil collection position is collected is 30 ° or more.
An insulating layer is formed on the exposed portion of the current collecting foil of the positive electrode sheet on the side where the positive electrode current collecting foil laminated portion is collected in the width direction, and the forming portion of the insulating layer is close to the negative electrode. It extends in the width direction to the outside of the
Here, the insulating layer includes an end portion of the insulating layer, a separator close to the end portion, and another positive electrode sheet in a state where at least the exposed portion of the current collecting foil of the positive electrode sheet at the farthest position is collected. A secondary battery that is formed so that there are no gaps between them.