JP2016122581A - Hermetically sealed secondary battery - Google Patents
Hermetically sealed secondary battery Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
Description
本発明は、密閉型二次電池(典型的には全体形状が角形(直方体形状)である密閉型二次電池)に関する。詳しくは、内圧上昇により作動する電流遮断機構を備えた密閉型二次電池に関する。 The present invention relates to a sealed secondary battery (typically a sealed secondary battery whose overall shape is a square (cuboid shape)). Specifically, the present invention relates to a sealed secondary battery provided with a current interrupting mechanism that operates by increasing internal pressure.
リチウム二次電池、ニッケル水素電池等の二次電池は、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源として好ましく用いられている。特に、軽量で高エネルギー密度が得られるリチウム二次電池は、電気自動車、ハイブリッド自動車等の車両の駆動用高出力電源として好ましく用いられるものとして期待されている。 In recent years, secondary batteries such as lithium secondary batteries and nickel metal hydride batteries are preferably used as so-called portable power sources such as personal computers and portable terminals, and vehicle drive power sources. In particular, a lithium secondary battery that is lightweight and has a high energy density is expected to be preferably used as a high-output power source for driving vehicles such as electric vehicles and hybrid vehicles.
このような二次電池の典型的な構造の一つとして、正極および負極を備える電極体を電解質とともに電池ケース内に密閉して成る密閉構造の電池(密閉型電池)が挙げられる。この種の電池を充電処理する際、不良電池の存在や充電装置の故障による誤作動等があった場合、電池に通常以上の電流が供給されて過充電状態に陥る場合が想定される。かかる過充電等の際に、電池反応が急速に進行して密閉された電池ケースの内部でガスが発生して該電池ケースの内圧が上昇し、当該異常内圧(ガス圧)によって該ケースの変形等を生じたりすることがあり得る。このような異常時に対処すべく、従来技術として、電池の異常時に伴うケース内部の圧力(ガス圧)を用いて部品を変形させ、通電部分を物理的に開裂させることにより電流を遮断する電流遮断機構を備えた電池構造が提案されている。 As one of typical structures of such a secondary battery, there is a sealed battery (sealed battery) in which an electrode body including a positive electrode and a negative electrode is sealed in a battery case together with an electrolyte. When charging this type of battery, if there is a malfunction due to the presence of a defective battery or a failure of the charging device, it is assumed that a current exceeding the normal level is supplied to the battery, resulting in an overcharged state. During such overcharge, the battery reaction proceeds rapidly, gas is generated inside the sealed battery case, the internal pressure of the battery case rises, and the abnormal internal pressure (gas pressure) deforms the case. Etc. may occur. In order to cope with such abnormalities, as a conventional technology, current interruption is performed by deforming parts using the pressure (gas pressure) inside the case that accompanies abnormalities in the battery and physically breaking the energized part. A battery structure with a mechanism has been proposed.
例えば、そのような構成の電流遮断機構を備えた二次電池に関する従来例として特許文献1が挙げられる。かかる文献に記載されている電流遮断機構は、角形状の密閉型二次電池のケース内部に収容された電極体に接続されたプレート状の集電板と、該集電板の一部に通電可能に溶接された反転板(電流遮断弁)とを備えており、ケース内圧(ガス圧)が上昇した際には当該ガス圧によって当該反転板が電極体および集電板から離れる方向に反転・変形し、その変形とともに上記溶接された部分を含む集電板の一部が破断されるように構成されている。このように反転板が反転・変形して集電板の本体から離脱することにより、電流遮断が実現される。 For example, Patent Document 1 is given as a conventional example related to a secondary battery having a current interruption mechanism having such a configuration. The current interrupting mechanism described in this document includes a plate-shaped current collector plate connected to an electrode body housed inside a case of a square-shaped sealed secondary battery, and energizing a part of the current collector plate. Inverted plate (current cutoff valve) welded as possible, and when the case internal pressure (gas pressure) rises, the gas plate reverses the reversing plate in the direction away from the electrode body and the current collector plate. The current collector plate is deformed and a part of the current collector plate including the welded portion is broken along with the deformation. In this way, current reversal is realized by reversing and deforming the reversing plate and separating from the main body of the current collecting plate.
上記特許文献1に記載されるような構成の電流遮断機構では、予め設定されたケース内圧(即ち所定のガス圧)に到達した際に正しく電流が遮断されることを実現するため、当該ケース内圧に到達した際に上記反転板(電流遮断弁)の反転・変形とともに上記溶接部分を含む集電板の一部の破断が速やかに行われるべく、集電板の当該溶接される部分およびその周囲を集電板の他の部分よりも相対的に薄肉に形成する、更に/或いは、破断させたい部位に予め溝(ノッチ:切り込み部)を形成する、等の措置が行われている。 In the current interruption mechanism configured as described in Patent Document 1 above, in order to realize that the current is correctly interrupted when reaching a preset case internal pressure (that is, a predetermined gas pressure), the case internal pressure In order to quickly break a part of the current collector plate including the welded portion together with the reversal / deformation of the reverse plate (current cutoff valve) when the current reaches the current plate, the welded portion of the current collector plate and its surroundings Measures are taken such as forming the wall relatively thinner than the other parts of the current collector plate and / or forming a groove (notch) in advance at a site to be broken.
ところで、電気自動車、ハイブリッド自動車(プラグインハイブリッド自動車を含む)等の車両の駆動電源用として使用される密閉型二次電池には、更なる高性能化のため、高出力で大容量(典型的には1時間率容量が3Ah以上、例えば5〜20Ah又は20Ah以上(例えば20〜30Ah)であるような大容量)の電池が求められる。このため、パソコンや携帯端末の電源として使用される(即ち民生用)電池とは比較にならないほどのハイレートな充放電が要求される。 By the way, a sealed secondary battery used as a drive power source for a vehicle such as an electric vehicle or a hybrid vehicle (including a plug-in hybrid vehicle) has a high output and a large capacity (typical) for further enhancement of performance. Requires a battery having an hourly capacity of 3 Ah or more, for example, 5 to 20 Ah or 20 Ah or more (for example, 20 to 30 Ah). For this reason, charging / discharging at a high rate that is incomparable with a battery used as a power source for a personal computer or a portable terminal (that is, a consumer product) is required.
しかし、従来の車両駆動電源用二次電池よりも一層のハイレートでの充放電が求められる場合、上記のような構成の電流遮断機構を備える密閉型二次電池においては、当該ハイレート充放電時においても正常に維持されて不測な動作を行わないように電流遮断機構を構築する必要がある。例えば、上記のとおり、所定のケース内圧(ガス圧)時に電流遮断弁(反転板)を速やかに反転・変形させ、集電板の一部を破断させるために当該集電板に形成された薄肉部分や溝(ノッチ)が形成された部分は、その部分の断面積が周囲の相対的に厚肉な部分の断面積よりも小さい。特に薄肉部分に更に溝を設けた場合には当該溝形成部の断面積は更に小さくなる。そのような小さい断面積の部分をハイレート充放電時に大電流が流れる際には、発生するジュール熱によって当該部分が発熱し、該発熱が過剰すぎる場合には当該箇所が過熱に伴って変形(クリープ)および溶断する虞がある。かかる変形(クリープ)および溶断は、電流遮断の原因となるため好ましくない。 However, when charging / discharging at a higher rate than that of a conventional secondary battery for vehicle driving power is required, in a sealed secondary battery having a current interruption mechanism having the above-described configuration, at the time of high-rate charging / discharging. However, it is necessary to construct a current interruption mechanism so that it is maintained normally and does not perform unexpected operations. For example, as described above, the thin wall formed on the current collector plate in order to quickly reverse and deform the current cutoff valve (reverse plate) at a predetermined case internal pressure (gas pressure) and to break a part of the current collector plate A portion or a portion where a groove (notch) is formed has a smaller cross-sectional area than that of a relatively thick portion around the portion. In particular, when a groove is further provided in the thin portion, the cross-sectional area of the groove forming portion is further reduced. When a large current flows through such a small cross-sectional area during high-rate charge / discharge, the part generates heat due to the generated Joule heat, and if the heat generation is excessive, the part deforms (creep) with overheating. ) And fusing. Such deformation (creep) and fusing are not preferable because they cause current interruption.
本発明はかかる点に鑑みてなされたものであり、その目的とするところは、電池の高出力化に伴うハイレート充放電時にも上記ジュール熱による集電板の変形(クリープ)および溶断を防止し、且つ、所定のケース内圧(ガス圧)が生じた場合には精度よく電流遮断を実現する信頼性の高い電流遮断機構を備えた密閉型二次電池を提供することである。 The present invention has been made in view of such a point, and the object of the present invention is to prevent deformation (creep) and fusing of the current collector plate due to Joule heat even during high-rate charge / discharge associated with higher output of the battery. In addition, it is an object of the present invention to provide a sealed secondary battery including a highly reliable current interrupting mechanism that realizes current interrupting accurately when a predetermined case internal pressure (gas pressure) occurs.
本発明者は予め破断用の溝が形成されたプレート形状の集電板と電流遮断弁を使用する電流遮断機構を採用する場合において、該集電板に形成された溝の形状に関して所定の条件を具備するように該集電板を設計することにより、上記目的を実現し得ることを見出して本発明を完成するに至った。
即ち、ここで開示される密閉型二次電池は、正極および負極を備える電極体と、上記電極体を収容する電池ケースと、上記電池ケースの外面に設けられて上記電極体の正極および負極とそれぞれ電気的に接続される正極外部端子および負極外部端子と、上記ケース内の内圧が所定レベルを超えて上昇した際に電流を遮断する電流遮断機構とを備える密閉型二次電池である。
上記電流遮断機構は、上記電極体の正極と上記正極外部端子との間または上記電極体の負極と上記負極外部端子との間において、上記正負いずれかの端子と電気的に接続される電流遮断弁と、上記電極体の正負いずれかの電極と電気的に接続されるプレート形状の集電板とを備える。
また、上記集電板は、相対的に薄肉に形成された中央薄肉部と該中央薄肉部の周囲であって相対的に厚肉に形成された厚肉部とから構成されており、且つ、該中央薄肉部の内側において所定の直径で環状に破断用の溝が形成されている。
また、上記電流遮断弁は、その一部が上記環状溝の内側において上記集電板の中央薄肉部に通電可能に接合されており、上記ケース内の内圧が所定レベルを超えて上昇した際には、該内圧によって電流遮断弁が上記集電板から離れる方向に変形するとともに上記環状溝の部分で上記集電板の中央薄肉部が破断することによって、上記集電板から上記破断した中央薄肉部を伴う電流遮断弁が離れて電流遮断が実現するように構成されている。
そして、ここで開示される密閉型二次電池は、上記薄肉部のうちの上記環状溝の底面に該当する部分に、当該環状溝の底面よりも凹んだ細孔が該溝の表面に沿って複数形成されていることを特徴とする。
In the case of adopting a plate-shaped current collector plate in which a breaking groove is formed in advance and a current interrupting mechanism using a current shut-off valve, the present inventor has predetermined conditions regarding the shape of the groove formed in the current collector plate. The present invention has been completed by finding that the above-mentioned object can be realized by designing the current collector plate to include
That is, a sealed secondary battery disclosed herein includes an electrode body including a positive electrode and a negative electrode, a battery case that houses the electrode body, and a positive electrode and a negative electrode of the electrode body that are provided on the outer surface of the battery case. A sealed secondary battery comprising a positive external terminal and a negative external terminal that are electrically connected to each other, and a current interrupt mechanism that interrupts current when the internal pressure in the case rises above a predetermined level.
The current interrupt mechanism is a current interrupt that is electrically connected to either the positive or negative terminal between the positive electrode of the electrode body and the positive external terminal or between the negative electrode of the electrode body and the negative external terminal. A valve, and a plate-shaped current collector electrically connected to either the positive or negative electrode of the electrode body.
Further, the current collector plate is composed of a central thin portion formed relatively thin and a thick portion formed relatively thick around the central thin portion, and A breaking groove is formed in an annular shape with a predetermined diameter inside the central thin portion.
The current cutoff valve is partly joined to the central thin portion of the current collector plate inside the annular groove so as to be energized, and when the internal pressure in the case rises above a predetermined level. The current cutoff valve is deformed in the direction away from the current collector plate by the internal pressure, and the central thin portion of the current collector plate is broken at the annular groove portion. The current cutoff valve with the part is separated and the current cutoff is realized.
In the sealed secondary battery disclosed here, a portion of the thin-walled portion corresponding to the bottom surface of the annular groove has pores recessed from the bottom surface of the annular groove along the surface of the groove. A plurality is formed.
ここで開示される密閉型二次電池において、該電池のケース内圧が所定の圧力に達すると、集電板の薄肉部のうちの環状溝の底面に形成された細孔(典型的には当該細孔の端部)に応力が集中し、当該応力が集中した細孔(典型的には当該細孔の端部)を起点として集電板が破断され得る。このため、ここで開示される密閉型二次電池に備えられる電流遮断機構は、従来の密閉型二次電池に備えられる集電板に設けられる環状溝の深さと比較して該環状溝の深さを浅くしても(即ち、上記集電板の薄肉部のうちの環状溝が形成された部分の残肉部の厚みを厚くしても)、電池ケース内の圧力(ケース内圧、ガス圧)が所定の圧力に達した際に電流遮断弁を速やかに変形させて集電板の一部を破断させることができる。即ち、ここで開示される密閉型二次電池に備えられる電流遮断機構によると、上記所定のケース内圧(ガス圧)時の電流遮断効果を高度に発揮しつつ、上記集電板の薄肉部のうちの環状溝形成部分の断面積を増大することができる。これにより、当該環状溝形成部分におけるジュール熱の発熱量を低減し、上記薄肉部(特に上記環状溝形成部分)における発熱(過熱)を抑制することができる。即ち、かかる構成の密閉型二次電池では、電池の高出力化に伴うハイレート充放電時における集電板の変形および溶断を防止し、且つ、所定のケース内圧(ガス圧)時に電流遮断弁を速やかに変形させて集電板の一部を破断させることができる。以上より、電池の高出力化に求められるハイレート充放電に対応して電流遮断機構の信頼性を向上させ、より高品質の密閉型二次電池(例えば密閉型リチウム二次電池)を提供することができる。 In the sealed secondary battery disclosed herein, when the internal pressure of the case of the battery reaches a predetermined pressure, the pores (typically, the pores formed in the bottom surface of the annular groove in the thin portion of the current collector plate). The stress concentrates on the end of the pore), and the current collector plate can be broken starting from the pore where the stress is concentrated (typically, the end of the pore). Therefore, the current interruption mechanism provided in the sealed secondary battery disclosed herein has a depth of the annular groove compared to the depth of the annular groove provided in the current collector plate provided in the conventional sealed secondary battery. Even if the thickness is shallow (that is, even if the thickness of the remaining portion of the thin portion of the current collector plate where the annular groove is formed), the pressure in the battery case (case internal pressure, gas pressure) When the pressure reaches a predetermined pressure, the current cutoff valve can be quickly deformed to break a part of the current collector plate. That is, according to the current interruption mechanism provided in the sealed secondary battery disclosed here, the current interruption effect at the predetermined case internal pressure (gas pressure) is highly exhibited, and the thin portion of the current collector plate The cross-sectional area of the annular groove forming portion can be increased. Thereby, the heat generation amount of Joule heat in the annular groove forming portion can be reduced, and the heat generation (overheating) in the thin wall portion (particularly, the annular groove forming portion) can be suppressed. That is, in the sealed secondary battery having such a configuration, the current collector plate is prevented from being deformed and blown at the time of high-rate charge / discharge accompanying the high output of the battery, and a current cutoff valve is provided at a predetermined case internal pressure (gas pressure). A part of the current collector plate can be broken by being quickly deformed. As described above, the reliability of the current interrupt mechanism is improved in response to the high rate charge / discharge required for high output of the battery, and a higher quality sealed secondary battery (for example, a sealed lithium secondary battery) is provided. Can do.
本明細書において「リチウム二次電池」とは、電解質イオンとしてリチウムイオンを利用し、正負極間におけるリチウムイオンに伴う電荷の移動により充放電が実現される二次電池をいう。一般にリチウムイオン電池(若しくはリチウムイオン二次電池)等と称される二次電池は、本明細書におけるリチウム二次電池に包含される典型例である。また、本明細書において「活物質」とは、正極側又は負極側において蓄電に関与する物質(化合物)をいう。即ち、電池の充放電時において電子の吸蔵および放出に関与する物質をいう。 In the present specification, the “lithium secondary battery” refers to a secondary battery that uses lithium ions as electrolyte ions and is charged / discharged by movement of charges accompanying the lithium ions between the positive and negative electrodes. A secondary battery generally called a lithium ion battery (or a lithium ion secondary battery) is a typical example included in the lithium secondary battery in this specification. Further, in this specification, the “active material” refers to a substance (compound) involved in power storage on the positive electrode side or the negative electrode side. That is, it refers to a substance that is involved in the insertion and extraction of electrons during battery charge / discharge.
以下、ここで開示される密閉型二次電池の一例としてリチウム二次電池(リチウムイオン電池)10に関する好適な一実施形態を図面を参照しつつ説明する。特に限定することを意図したものではないが、以下では捲回タイプの電極体(以下「捲回電極体」という。)と非水電解液とを角形(即ち直方体の箱形状)のケースに収容した形態のリチウムイオン電池を例として説明する。各図における寸法関係(長さ、幅、厚さ等)は実際の寸法関係を反映するものではない。また、同じ作用を奏する部材・部位には同じ符号を付し、重複する説明は省略または簡略化する。
なお、本発明はここで開示される構成の電流遮断機構を有する限りにおいて、二次電池の種類はリチウム二次電池(典型的には非水電解質を備えたリチウムイオン電池)に限定されず、ニッケル水素電池その他の二次電池にも適用することができる。
Hereinafter, a preferred embodiment relating to a lithium secondary battery (lithium ion battery) 10 as an example of a sealed secondary battery disclosed herein will be described with reference to the drawings. Although not intended to be particularly limited, hereinafter, a wound type electrode body (hereinafter referred to as a “wound electrode body”) and a non-aqueous electrolyte are accommodated in a rectangular (that is, a rectangular box shape) case. A lithium ion battery having the above-described form will be described as an example. The dimensional relationship (length, width, thickness, etc.) in each figure does not reflect the actual dimensional relationship. Further, members / parts having the same action are denoted by the same reference numerals, and redundant description is omitted or simplified.
Note that the present invention is not limited to a lithium secondary battery (typically a lithium ion battery having a nonaqueous electrolyte) as long as it has a current interruption mechanism having a configuration disclosed herein, The present invention can also be applied to nickel metal hydride batteries and other secondary batteries.
本実施形態に係るリチウムイオン電池10は、図2に示すような扁平形状の捲回電極体50が、図示しない液状電解質(電解液)とともに、捲回電極体50の形状に対応する図1に示すような扁平な角形状の電池ケース(即ち外装容器)12に収容されて構成される電池である。
電池ケース12は、一端(電池10の通常の使用状態における上端部に相当する。)に開口部を有する箱形(すなわち有底直方体状)のケース本体14と、その開口部に取り付けられて該開口部を塞ぐ矩形状プレート部材からなる封口板(蓋体)16とから構成される。かかる封口板(蓋体)16がケース本体14の開口部周縁に溶接されることにより、扁平形状の捲回電極体50の幅広面に対向する一対のケース幅広面と、該ケース幅広面に隣接する4つの矩形状ケース面(即ち、そのうちの一つの矩形状ケース上面が封口板16により構成される。)との六面体形状の密閉構造の電池ケース12が構成される。
特に制限するものではないが、この種の角形電池の六面体形状ケースの好適なサイズとして、ケース本体14及び封口板16の長辺側の長さ:約80〜200mm(例えば100〜150mm)、ケース本体14及び封口板16の短辺側の長さ(即ちケース12の厚み):約8〜25mm(例えば10〜20mm)、ケース12の高さ:約70〜150mmを例示することができる。
In the lithium ion battery 10 according to the present embodiment, a flat wound electrode body 50 as shown in FIG. 2 corresponds to the shape of the wound electrode body 50 together with a liquid electrolyte (electrolytic solution) not shown in FIG. The battery is configured to be accommodated in a flat rectangular battery case (that is, an exterior container) 12 as shown.
The battery case 12 has a box-shaped (that is, a bottomed rectangular parallelepiped) case body 14 having an opening at one end (corresponding to the upper end in a normal use state of the battery 10), and is attached to the opening. It is comprised from the sealing board (lid body) 16 which consists of a rectangular-shaped plate member which plugs up an opening part. The sealing plate (lid body) 16 is welded to the peripheral edge of the opening of the case body 14, so that a pair of case wide surfaces facing the wide surface of the flat wound electrode body 50 and the case wide surface are adjacent to each other. A battery case 12 having a hexahedron-shaped sealed structure with four rectangular case surfaces (that is, one of the rectangular case upper surfaces is constituted by the sealing plate 16) is formed.
Although it does not restrict | limit in particular, As a suitable size of the hexahedron shape case of this kind of square battery, the length of the long side of the case main body 14 and the sealing board 16: about 80-200 mm (for example, 100-150 mm), a case The length on the short side of the main body 14 and the sealing plate 16 (that is, the thickness of the case 12): about 8 to 25 mm (for example, 10 to 20 mm), and the height of the case 12: about 70 to 150 mm can be exemplified.
ケース12の材質は、従来の密閉型電池で使用されるものと同じであればよく、特に制限はない。軽量で熱伝導性の良い金属材料を主体に構成されたケース12が好ましく、このような金属製材料としてアルミニウム、ステンレス鋼、ニッケルめっき鋼等が例示される。本実施形態に係るケース12(ケース本体14および封口板16)はアルミニウム若しくはアルミニウムを主体とする合金によって構成されている。
また、ケース12(ケース本体14および封口板16)の厚みは、特に限定されないが、車両駆動電源用の密閉型電池を構成する場合、0.3mm〜2mm程度が適当であり、0.5mm〜1mm程度が好ましい。
The material of case 12 should just be the same as what is used with the conventional sealed battery, and there is no restriction | limiting in particular. A case 12 mainly composed of a metal material that is lightweight and has good thermal conductivity is preferable. Examples of such a metal material include aluminum, stainless steel, nickel-plated steel, and the like. The case 12 (the case main body 14 and the sealing plate 16) according to the present embodiment is made of aluminum or an alloy mainly composed of aluminum.
Further, the thickness of the case 12 (the case main body 14 and the sealing plate 16) is not particularly limited, but in the case of constituting a sealed battery for a vehicle driving power source, about 0.3 mm to 2 mm is appropriate, and 0.5 mm to About 1 mm is preferable.
図1に示すように、封口板16には外部接続用の正極外部端子20および負極外部端子18が形成されている。これら外部端子18,20には、本実施形態に係るリチウムイオン電池10の利用形態に応じて適当な形状の端子板若しくは外部接続端子を装着し得る。
封口板16の両端子18,20間には、ケース12の内圧が所定レベル(例えば設定開弁圧0.3〜1.0MPa程度)以上に上昇した場合に該内圧を開放するように構成された薄肉の安全弁40と、注液口42(図1は当該注液口42が注液後に封止材43により封止されてマスクされた状態である。)が形成されている。
As shown in FIG. 1, a positive electrode external terminal 20 and a negative electrode external terminal 18 for external connection are formed on the sealing plate 16. These external terminals 18 and 20 can be equipped with a terminal plate or an external connection terminal having an appropriate shape according to the usage pattern of the lithium ion battery 10 according to the present embodiment.
Between the two terminals 18 and 20 of the sealing plate 16, the internal pressure is released when the internal pressure of the case 12 rises to a predetermined level (for example, a set valve opening pressure of about 0.3 to 1.0 MPa). A thin safety valve 40 and a liquid injection port 42 (FIG. 1 is a state in which the liquid injection port 42 is sealed and masked by a sealing material 43 after liquid injection) are formed.
図2に示すように、捲回電極体50は通常のリチウムイオン電池の捲回電極体と同様、長尺なシート状正極(正極シート)52と、該正極シート52と同様の図示されない長尺シート状負極(負極シート)とを計二枚の長尺シート状セパレータ(セパレータシート)54とともに積層して長手方向に捲回し、次いで得られた捲回体を側面方向から押しつぶして拉げさせることによって作製される。具体的には、正極シート52と負極シートとは幅方向に位置をややずらしてセパレータシート54の幅方向の一端および他端から該正負いずれかのシートの幅方向の一端がそれぞれはみ出すように積層された状態で捲回される。その結果として、捲回電極体50の捲回軸方向の一方および他方の端部に、それぞれ、正極シート52および負極シートの幅方向の一端が捲回コア部55(すなわち正極シートと負極シートとセパレータシートとが密に捲回された部分)から外方にはみ出した部分が形成されている。 As shown in FIG. 2, the wound electrode body 50 has a long sheet-like positive electrode (positive electrode sheet) 52 and a long length (not shown) similar to the positive electrode sheet 52, similar to a wound electrode body of a normal lithium ion battery. A sheet-like negative electrode (negative electrode sheet) is laminated together with a total of two long sheet-like separators (separator sheets) 54 and wound in the longitudinal direction, and then the obtained wound body is crushed from the side direction and abducted. It is produced by. Specifically, the positive electrode sheet 52 and the negative electrode sheet are slightly shifted in the width direction so that one end in the width direction of either the positive or negative sheet protrudes from one end and the other end in the width direction of the separator sheet 54. It is wound in the state that was done. As a result, one end of the wound electrode body 50 in the winding axis direction and one end in the width direction of the positive electrode sheet 52 and the negative electrode sheet respectively are wound core portions 55 (that is, the positive electrode sheet and the negative electrode sheet). A portion protruding outward from a portion where the separator sheet is wound tightly is formed.
図2には、正極シート52のはみ出し部分52Aが図示されており、かかる正極シート52のはみ出し部分52Aに対して、ケース12の内部に配置される正極集電タブ60および正極内部端子70を介して上記外部接続用の正極外部端子20と電気的に接続されている。図示しない負極側も同様に、ケース12の内部に配置される図示しない負極集電タブおよび負極集電板を介して上記外部接続用の負極外部端子18と電気的に接続されている。
なお、本実施形態に係るリチウムイオン電池10において、電流遮断機構80は、正極外部端子20の一部と、正極内部端子70の一部と、電流遮断弁(反転板)30により構成されている。かかる電流遮断機構80については後述する。
FIG. 2 shows a protruding portion 52 </ b> A of the positive electrode sheet 52, and the protruding portion 52 </ b> A of the positive electrode sheet 52 is interposed via a positive electrode current collecting tab 60 and a positive electrode internal terminal 70 disposed inside the case 12. Thus, the external connection positive electrode external terminal 20 is electrically connected. Similarly, the negative electrode side (not shown) is also electrically connected to the negative electrode external terminal 18 for external connection via a negative electrode current collector tab and a negative electrode current collector plate (not shown) arranged inside the case 12.
In the lithium ion battery 10 according to the present embodiment, the current cutoff mechanism 80 includes a part of the positive external terminal 20, a part of the positive internal terminal 70, and a current cutoff valve (reversing plate) 30. . The current interruption mechanism 80 will be described later.
捲回電極体50を構成する材料および部材自体は、従来のリチウムイオン電池に備えられる電極体と同様でよく、特に制限はない。例えば正極シート52は、長尺状の正極集電体(例えばアルミニウム箔)の上に正極活物質層が形成された構成であり得る。この正極活物質層の形成に用いる正極活物質としては、従来からリチウムイオン電池に用いられる物質の一種または二種以上を特に限定なく使用することができる。好適例として、リチウムニッケル酸化物(例えばLiNiO2)、リチウムコバルト酸化物(例えばLiCoO2)、リチウムマンガン酸化物(例えばLiMn2O4)等のリチウムと遷移金属元素とを構成金属元素として含む酸化物(リチウム遷移金属酸化物)や、リン酸マンガンリチウム(LiMnPO4)、リン酸鉄リチウム(LiFePO4)等のリチウムと遷移金属元素とを構成金属元素として含むリン酸塩等が挙げられる。
負極シートは、長尺状の負極集電体(例えば銅箔)の上に負極活物質層が形成された構成であり得る。この負極活物質層の形成に用いる負極活物質としては、従来からリチウムイオン電池に用いられる物質の一種または二種以上を特に限定なく使用することができる。好適例として、グラファイトカーボン、アモルファスカーボン等の炭素系材料、リチウム遷移金属酸化物、リチウム遷移金属窒化物等が挙げられる。また、上記セパレータシートの好適例としては、多孔質ポリオレフィン系樹脂で構成されたものが挙げられる。
The material and the member itself constituting the wound electrode body 50 may be the same as those of the electrode body provided in the conventional lithium ion battery, and are not particularly limited. For example, the positive electrode sheet 52 may have a configuration in which a positive electrode active material layer is formed on a long positive electrode current collector (for example, an aluminum foil). As the positive electrode active material used for forming this positive electrode active material layer, one or two or more materials conventionally used in lithium ion batteries can be used without particular limitation. As a preferred example, an oxide containing lithium and a transition metal element as constituent metal elements such as lithium nickel oxide (for example, LiNiO 2 ), lithium cobalt oxide (for example, LiCoO 2 ), and lithium manganese oxide (for example, LiMn 2 O 4 ). And a phosphate containing lithium and a transition metal element as constituent metal elements, such as lithium oxide (lithium transition metal oxide), lithium manganese phosphate (LiMnPO 4 ), and lithium iron phosphate (LiFePO 4 ).
The negative electrode sheet may have a configuration in which a negative electrode active material layer is formed on a long negative electrode current collector (for example, copper foil). As the negative electrode active material used for forming this negative electrode active material layer, one or two or more materials conventionally used in lithium ion batteries can be used without particular limitation. Preferable examples include carbon-based materials such as graphite carbon and amorphous carbon, lithium transition metal oxides, lithium transition metal nitrides, and the like. Moreover, as a suitable example of the said separator sheet, what was comprised with porous polyolefin resin is mentioned.
液状電解質(電解液)としては、従来からリチウムイオン電池に用いられる非水電解液と同様のものを特に限定なく使用することができる。かかる非水電解液は、典型的には、適当な非水溶媒に支持塩を含有させた組成を有する。上記非水溶媒としては、例えば、エチレンカーボネート、プロピレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート、1,2−ジメトキシエタン、1,2−ジエトキシエタン、テトラヒドロフラン、1,3−ジオキソラン等からなる群から選択された一種または二種以上を用いることができる。また、上記支持塩としては、例えば、LiPF6,LiBF4,LiAsF6,LiCF3SO3,LiC4F9SO3,LiN(CF3SO2)2,LiC(CF3SO2)3等のリチウム塩を用いることができる。一例として、エチレンカーボネートとジエチルカーボネートとの混合溶媒(例えば質量比1:1)にLiPF6を約1mol/Lの濃度で含有させた非水電解液が挙げられる。なお、電解液の代わりに固体状やゲル状の電解質を採用してもよい。 As the liquid electrolyte (electrolytic solution), the same non-aqueous electrolytic solution conventionally used in lithium ion batteries can be used without particular limitation. Such a non-aqueous electrolyte typically has a composition in which a supporting salt is contained in a suitable non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,3-dioxolane, and the like. One kind or two or more kinds selected from the group can be used. Examples of the supporting salt include LiPF 6 , LiBF 4 , LiAsF 6 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 and the like. Lithium salts can be used. As an example, a nonaqueous electrolytic solution in which LiPF 6 is contained in a mixed solvent of ethylene carbonate and diethyl carbonate (for example, a mass ratio of 1: 1) at a concentration of about 1 mol / L can be given. A solid or gel electrolyte may be used instead of the electrolytic solution.
以下、電流遮断機構80について図面を参照しつつ詳述する
図2に示すように、捲回電極体50の捲回軸方向の一方の端部にはみ出した正極はみ出し部分52Aには、電気伝導性に優れた金属製(例えばアルミニウム又はアルミニウム主体の合金製)の正極集電タブ60が接続されている。かかる集電タブ60から上方(即ち封口板方向)に延びるようにして電気伝導性に優れた金属製(例えばアルミニウム又はアルミニウム主体の合金製)の正極内部端子70が形成されている。正極内部端子70は、封口板16の内面側に近接して当該内面とほぼ平行に配置されるプレート形状(典型的には矩形のプレート形状、例えば長方形のプレート形状)の集電板72と、該集電板72と正極集電タブ60とを連結するアーム状の連結部71とから構成されている。
集電板72は、後述する電流遮断弁(反転板)30の一部(中央凹部30A)が溶接される中央薄肉部74とその周囲の相対的に厚い厚肉部78とから構成されている。中央薄肉部は典型的には円形状若しくは矩形状に形成される。また、図2に示すように、中央薄肉部74の中心部ならびに厚肉部78の複数箇所(本実施形態では2箇所)に、ガス流通孔74A,78Aが形成されている。また、図3に示すように、中央薄肉部74の内側において所定の直径で環状に破断用の溝(ノッチ)79が形成されている。かかる破断用の環状溝(ノッチ)79は、図3に示すように、集電板72の薄肉部78の表面のうち、電極体50に対向する面、或いは絶縁ホルダー32に対向する面のいずれに形成してもよい。また、上記環状溝79を横切る位置に適宜切り込みを設けてもよい。かかる切り込みを形成することで、集電板72の薄肉部74が変形する際の周方向の変形阻害を抑制し、集電板72が変形するのに必要な応力(変形応力)を低減することができる。
Hereinafter, the current interrupting mechanism 80 will be described in detail with reference to the drawings. As shown in FIG. 2, the positive electrode protruding portion 52A protruding from one end portion in the winding axis direction of the wound electrode body 50 is electrically conductive. A positive electrode current collecting tab 60 made of metal (for example, made of aluminum or an alloy mainly composed of aluminum) is connected. A positive electrode internal terminal 70 made of metal (for example, made of aluminum or an aluminum-based alloy) having excellent electrical conductivity is formed so as to extend upward (that is, in the sealing plate direction) from the current collecting tab 60. The positive electrode internal terminal 70 has a plate-like current collector plate 72 (typically a rectangular plate shape, for example, a rectangular plate shape) that is disposed in proximity to the inner surface side of the sealing plate 16 and substantially parallel to the inner surface. The current collecting plate 72 and the positive current collecting tab 60 are configured by an arm-shaped connecting portion 71 that connects the current collecting plate 72 and the positive current collecting tab 60.
The current collecting plate 72 is composed of a central thin portion 74 to which a part (central recess 30A) of a current cutoff valve (reversing plate) 30 described later is welded and a relatively thick thick portion 78 around the central thin portion 74. . The central thin portion is typically formed in a circular shape or a rectangular shape. Further, as shown in FIG. 2, gas flow holes 74 </ b> A and 78 </ b> A are formed at a central portion of the central thin portion 74 and a plurality of locations (two locations in the present embodiment) of the thick portion 78. Further, as shown in FIG. 3, a breaking groove (notch) 79 is formed in a ring shape with a predetermined diameter inside the central thin portion 74. As shown in FIG. 3, the annular groove (notch) 79 for breakage is either a surface facing the electrode body 50 or a surface facing the insulating holder 32 among the surfaces of the thin portion 78 of the current collector plate 72. You may form in. Further, an appropriate cut may be provided at a position crossing the annular groove 79. By forming such a cut, it is possible to suppress deformation inhibition in the circumferential direction when the thin portion 74 of the current collector plate 72 is deformed, and to reduce stress (deformation stress) necessary for the current collector plate 72 to be deformed. Can do.
図5に示すように、環状溝79の底面には、当該環状溝79の底面よりも凹んだ細孔76が該溝の底面に沿って複数個(例えば30〜130個、好ましくは64〜112個)環状に形成されている。また、各細孔は、細孔76の中心と細孔76の中心とが等間隔に配置されることが好ましい。かかる細孔76は、貫通孔あるいは非貫通孔のいずれであってもよい。貫通孔は、細孔端部に応力を集中させやすく、該応力集中部において集電板を好適に破断し得るため好ましい。細孔76の形状は特に限定されないが、集電板72について当該細孔76が形成された面を平面視したときの該細孔76の形状が略円形状(典型的には円形)、即ち円柱状の細孔であり得る。 As shown in FIG. 5, the bottom surface of the annular groove 79 has a plurality of (for example, 30 to 130, preferably 64 to 112) pores 76 that are recessed from the bottom surface of the annular groove 79. Are formed in an annular shape. Moreover, it is preferable that the center of the pore 76 and the center of the pore 76 are arrange | positioned at equal intervals for each pore. The pores 76 may be either through holes or non-through holes. The through hole is preferable because stress can be easily concentrated on the end portion of the pore, and the current collector plate can be suitably broken at the stress concentration portion. The shape of the pores 76 is not particularly limited, but the shape of the pores 76 when the surface of the current collector plate 72 on which the pores 76 are formed is viewed in plan view (typically circular), that is, It may be a cylindrical pore.
特に限定されるものではないが、車両の駆動電源用として使用する電池の場合、かかる集電板72の短辺の長さ(短径)は典型的には6mm〜15mm程度であり、集電板72の長辺側の長さ(長径)は典型的には短径の2〜5倍程度に規定される。
なお、中央薄肉部74の大きさは特に制限はないが、集電板72の短径の長さの40〜70%に相当する長さ(例えば集電板72の短径が8mmの場合で3.2mm〜5.6mm)を直径とする円形若しくは方形状に形成されることが適当である。
環状溝79の直径は2mm以上(典型的には3mm以上6mm以下)であることが好ましい。また、環状溝79の形成位置であるが、集電板72の変形および溶断に対する抵抗性(耐熱性)向上の観点から、厚肉部78と環状溝79との距離が1mm以下であることが適当であり、0.4〜0.6mm(例えば0.5mm±0.05mm程度)が好ましい。
Although not particularly limited, in the case of a battery used as a drive power source for a vehicle, the length (short axis) of the short side of the current collecting plate 72 is typically about 6 mm to 15 mm. The length (major axis) on the long side of the plate 72 is typically defined to be about 2 to 5 times the minor axis.
The size of the central thin portion 74 is not particularly limited, but is a length corresponding to 40 to 70% of the length of the minor axis of the current collector plate 72 (for example, when the minor axis of the current collector plate 72 is 8 mm). It is appropriate to form a circular or square shape having a diameter of 3.2 mm to 5.6 mm.
The diameter of the annular groove 79 is preferably 2 mm or more (typically 3 mm or more and 6 mm or less). Moreover, although it is a formation position of the cyclic | annular groove | channel 79, from a viewpoint of the resistance (heat resistance) improvement with respect to the deformation | transformation and fusing of the current collecting plate 72, the distance of the thick part 78 and the cyclic | annular groove | channel 79 may be 1 mm or less. It is suitable, and 0.4 to 0.6 mm (for example, about 0.5 mm ± 0.05 mm) is preferable.
厚肉部78の厚みは典型的には2mm以下(例えば0.4mm〜2mm)であり、1mm以下(例えば0.5mm〜1mm)が好ましい。中央薄肉部74の厚みは典型的には0.2mm以下(例えば0.05mm〜0.2mm)であり、0.15mm以下(例えば0.08mm〜0.15mm)が好ましい。
環状溝79の深さ(切り込み深さ)は、当該環状溝79形成部分における残肉部のうちの最薄部分の厚みが少なくとも0.03mm以上となるように設定することが適当であり、例えば0.05mm以上、典型的には0.08mm以上となるように設定することが好ましい。残肉部の厚みが小さすぎると、当該環状溝79形成部分の発熱が大きくなり過ぎて集電板(典型的には集電板の薄肉部のうちの環状溝79形成部分)が変形(クリープ)および溶断する虞があるため好ましくない。一方で、残肉部の厚みが多すぎると、所定のケース内圧発生時に上記集電板の破断が困難となるため好ましくない。このため、上記環状溝79の深さ(切り込み深さ)は、当該環状溝形成部分における残肉部のうちの最薄部分の厚みが例えば0.15mm以下、典型的には0.12mm以下、一般的には0.10mm以下となるように設定することが好ましい。
The thickness of the thick portion 78 is typically 2 mm or less (for example, 0.4 mm to 2 mm), and preferably 1 mm or less (for example, 0.5 mm to 1 mm). The thickness of the central thin portion 74 is typically 0.2 mm or less (for example, 0.05 mm to 0.2 mm), and preferably 0.15 mm or less (for example, 0.08 mm to 0.15 mm).
The depth (incision depth) of the annular groove 79 is suitably set so that the thickness of the thinnest portion of the remaining portion in the annular groove 79 forming portion is at least 0.03 mm or more. It is preferable to set it to be 0.05 mm or more, typically 0.08 mm or more. If the thickness of the remaining portion is too small, the heat generation in the annular groove 79 forming portion becomes too large, and the current collector plate (typically, the annular groove 79 forming portion in the thin wall portion of the current collector plate) is deformed (creep). ) And fusing. On the other hand, when the thickness of the remaining portion is too large, it is not preferable because it is difficult to break the current collector plate when a predetermined internal pressure is generated. For this reason, the depth (cut depth) of the annular groove 79 is such that the thickness of the thinnest portion of the remaining portion in the annular groove forming portion is, for example, 0.15 mm or less, typically 0.12 mm or less, Generally, it is preferable to set it to be 0.10 mm or less.
また、上記細孔を環状溝79の底面に形成することで、環状溝79形成部分の集電板の断面積を大きくしたとしても、所定のケース内圧(ガス圧)が生じた場合には精度よく電流遮断を実現することができる。換言すると、本発明における集電板の環状溝79形成部分の断面積は、環状溝79の底部に細孔76が形成されていない集電板72における環状溝79形成部分の断面積よりも大きく(例えば1.1倍以上、典型的には1.2倍以上、好ましくは1.6倍以上)することができる。ここで、本明細書において集電板72の環状溝79形成部分の断面積とは、環状溝79の環の中心を通過するように集電板72を厚み方向に切断したときの環状溝79形成部分の集電板72(即ち、集電板の残肉部)の断面積であって、当該断面積が最小となる断面(典型的には細孔76の中心を通過するように切断した断面)の断面積をいう。 Further, even if the cross-sectional area of the current collector plate in the annular groove 79 forming portion is increased by forming the above-mentioned pores on the bottom surface of the annular groove 79, it is accurate when a predetermined case internal pressure (gas pressure) occurs. A current interruption can be realized well. In other words, the cross-sectional area of the current collector plate where the annular groove 79 is formed is larger than the cross-sectional area of the current collector plate 72 where the pores 76 are not formed in the bottom of the annular groove 79. (For example, 1.1 times or more, typically 1.2 times or more, preferably 1.6 times or more). Here, in this specification, the cross-sectional area of the annular groove 79 forming portion of the current collector plate 72 is the annular groove 79 when the current collector plate 72 is cut in the thickness direction so as to pass through the center of the ring of the annular groove 79. The cross-sectional area of the current collector plate 72 (that is, the remaining portion of the current collector plate) at the formation portion, and the cross-section where the cross-sectional area is the smallest (typically cut so as to pass through the center of the pore 76) Section).
細孔76の大きさは特に限定されないが、当該細孔76の直径が環状溝79の幅よりも小さくなるように設定することが好ましい。典型的には0.02mm以上0.1mm以下(例えば0.04mm以上0.08mm以下、好ましくは0.06mm±0.01mm程度)が適当である。また、上記細孔76を形成する間隔は、例えば、2つの細孔76の中心間の距離が、細孔76の直径の1.8倍〜4倍程度が適当である。細孔76の直径および細孔76の間隔を適宜調整することで、集電板72が破断する圧力(反転圧)を設計することができる。
このような細孔76の形成方法は、特に限定されず、公知の細孔形成方法を採用すればよい。例えば放電加工、或いはレーザ加工等の手法によって形成することができる。
The size of the pores 76 is not particularly limited, but is preferably set so that the diameter of the pores 76 is smaller than the width of the annular groove 79. Typically, 0.02 mm to 0.1 mm (for example, 0.04 mm to 0.08 mm, preferably about 0.06 mm ± 0.01 mm) is appropriate. The interval between the pores 76 is suitably set such that the distance between the centers of the two pores 76 is about 1.8 to 4 times the diameter of the pores 76. By appropriately adjusting the diameter of the pores 76 and the interval between the pores 76, the pressure (reversing pressure) at which the current collector plate 72 breaks can be designed.
The formation method of such a pore 76 is not specifically limited, What is necessary is just to employ | adopt a well-known pore formation method. For example, it can be formed by a technique such as electric discharge machining or laser machining.
図3に示すように、本実施形態に係る正極外部端子20は、封口板16の外面側(図3の上方向)において、封口板16に予め形成されている正極装着孔16Aに装着される筒状の接続端子22と、該筒状接続端子22と封口板16(装着孔16Aの周縁)との間に挟み込まれるガスケット24とを備える。筒状接続端子22の貫通孔22B内には、ゴム製の端子栓23が封入される。
さらに本実施形態に係る正極外部端子20は、封口板16の内面側(図3の下方向)において、上記筒状接続端子22が挿入され得る挿入孔がそれぞれ形成されたキャップ状の合成樹脂製の絶縁板26および金属製の封口体タブ28を備える。
より具体的には、図3に示すように、正極内部端子70と電気的に接続される筒状接続端子22は、ガスケット24、封口板16、絶縁板26および封口体タブ28にそれぞれ形成された孔内に挿入され、その先端部22Cが図示されるようにかしめられることにより、これら部材22,24,16,26,28が一体に固定される。
As shown in FIG. 3, the positive electrode external terminal 20 according to the present embodiment is mounted in a positive electrode mounting hole 16 </ b> A formed in advance on the sealing plate 16 on the outer surface side (upward direction in FIG. 3) of the sealing plate 16. A cylindrical connection terminal 22 and a gasket 24 sandwiched between the cylindrical connection terminal 22 and the sealing plate 16 (periphery of the mounting hole 16A) are provided. A rubber terminal plug 23 is sealed in the through hole 22B of the cylindrical connection terminal 22.
Furthermore, the positive electrode external terminal 20 according to the present embodiment is made of a cap-shaped synthetic resin in which insertion holes into which the cylindrical connection terminals 22 can be inserted are formed on the inner surface side (downward in FIG. 3) of the sealing plate 16. The insulating plate 26 and the metal sealing member tab 28 are provided.
More specifically, as shown in FIG. 3, the cylindrical connection terminals 22 electrically connected to the positive electrode internal terminal 70 are respectively formed on the gasket 24, the sealing plate 16, the insulating plate 26, and the sealing body tab 28. The members 22, 24, 16, 26, and 28 are integrally fixed by being inserted into the holes and caulking the tip 22 C as shown in the figure.
また、かかるキャップ状の封口体タブ28の縁部には、プレート状の電流遮断弁として機能する反転板30が溶接されており、さらに集電板72および反転板30の周辺部には、当該集電板72および反転板30の位置決めと周辺部の電気的絶縁とを目的として合成樹脂製の絶縁ホルダー32が配置されている。
また、プレート状の反転板30の中央部は、対応する絶縁ホルダー32の中央部に形成された孔を介して集電板72の中央薄肉部74に接するように凹んでおり、かかる反転板30の中央凹部30Aはレーザ溶接あるいは超音波溶接によって集電板72の中央薄肉部74の環状溝79の内側に接合されている。換言すれば、正極内部端子70の集電板72の中央薄肉部74において、上記反転板30の中央凹部30Aの接合箇所の周囲に破断用環状溝79が存在する。
上記構成の結果、正極シート52は、正極はみ出し部分52A、集電タブ60、正極内部端子70、反転板30および封口体タブ28を介して接続端子22と電気的に接続される。
Further, the reversing plate 30 functioning as a plate-like current cutoff valve is welded to the edge of the cap-shaped sealing body tab 28, and the current collecting plate 72 and the peripheral portion of the reversing plate 30 are connected to the periphery of the reversing plate 30. An insulating holder 32 made of synthetic resin is disposed for the purpose of positioning the current collecting plate 72 and the reversing plate 30 and electrically insulating the peripheral portion.
Further, the central portion of the plate-like reversing plate 30 is recessed so as to contact the central thin portion 74 of the current collector plate 72 through a hole formed in the central portion of the corresponding insulating holder 32. The central recess 30A is joined to the inside of the annular groove 79 of the central thin portion 74 of the current collector plate 72 by laser welding or ultrasonic welding. In other words, in the central thin portion 74 of the current collector plate 72 of the positive electrode internal terminal 70, the fracture annular groove 79 exists around the joint portion of the central recess 30A of the reversing plate 30.
As a result of the above configuration, the positive electrode sheet 52 is electrically connected to the connection terminal 22 through the positive electrode protruding portion 52A, the current collecting tab 60, the positive electrode internal terminal 70, the reversing plate 30, and the sealing body tab 28.
そして反転板30は、電池ケース12内の圧力(ガス圧)が所定値以上に増大すると、接続端子22側に撓んで変形する(典型的には接続端子22側に反転・変形する)ように形成されているとともに、当該反転板30の中央凹部30Aに集電板72が溶接されているため、ケース12内の圧力が所定値を超えて反転板30が上記のように変形した際はそれに伴って集電板72の薄肉部74が環状溝79の部分で破断する。このことにより、図4に示すように、反転板30と集電板72との間の電気的接続が遮断される。なお、本実施形態に係る電流遮断機構80は正極外部端子20側に設けられているが、この態様に限られず、負極外部端子18側に設けられていてもよい。 When the pressure (gas pressure) in the battery case 12 increases to a predetermined value or more, the reversing plate 30 is bent and deformed to the connection terminal 22 side (typically reversing and deforming to the connection terminal 22 side). Since the current collecting plate 72 is welded to the central recess 30A of the reversing plate 30 when the reversing plate 30 is deformed as described above when the pressure in the case 12 exceeds a predetermined value, Accordingly, the thin portion 74 of the current collector plate 72 is broken at the annular groove 79. Thereby, as shown in FIG. 4, the electrical connection between the reversing plate 30 and the current collecting plate 72 is interrupted. In addition, although the electric current interruption mechanism 80 which concerns on this embodiment is provided in the positive electrode external terminal 20 side, it is not restricted to this aspect, You may be provided in the negative electrode external terminal 18 side.
以下、本発明によって提供される集電板に関する具体的な試験例の幾つかを紹介するが、本発明によって提供される集電板を以下に紹介する形態のものに限定することを意図したものではない。 Hereinafter, some specific test examples relating to the current collector provided by the present invention will be introduced, but the current collector provided by the present invention is intended to be limited to the form introduced below. is not.
環状溝79が図6に示す形状である計5種類(サンプル1,2,3,4および5)のプレート形状のアルミニウム製集電板72を設計し、各サンプルついてCAE(computer aided engineering)解析にて応力解析を行った。サンプル1〜3および5は、当該集電板72を備えた電流遮断機構80を用いて電池10を構築した場合に絶縁ホルダー32に対向する面に環状溝79を形成し、サンプル4は、サンプル1〜3および5の環状溝形成面とは逆の面(即ち、電池構築時に電極体50に対向する面)に環状溝79を形成した。なお、各サンプルに係る集電板72は、環状溝79の深さ(残肉部の厚み)、環状溝79の形成面、環状溝形成部分の断面積、細孔76の間隔以外は同様のパラメータとなるように設計した。
サンプル1に係る集電板72の環状溝79は、所定の応力が負荷された際に(かかる集電板72を備えた電流遮断機構80を備えた電池10のケース内圧が所定の圧力に達した際)に破断されるように設計された、従来の集電板72に形成される環状溝79と同様の形状の環状溝79であり、残肉部のうちの最薄部分の厚みを0.075mmとした。また、サンプル2に係る集電板72の環状溝79は、上記サンプル1の環状溝79よりも切り込み深さが浅く(即ち、残肉部の厚みが厚い)、残肉部のうちの最薄部分の厚みを0.15mmとした。また、サンプル3〜5に係る集電板72の環状溝79の底面には、直径0.06mmの貫通孔(細孔76)を形成し、サンプル3とサンプル4は細孔間隔が同じになるように、またサンプル5はサンプル3、4よりも細孔間隔が広くなるように設計した。なお、サンプル3〜5について、残肉部のうちの最薄部分の厚みはサンプル2と同様に0.15mmとした。各サンプルに係る集電板72の環状溝形成部分の断面積について、サンプル1における環状溝形成部分の断面積を100%としたときの相対比として図9に示す。
A total of five types (samples 1, 2, 3, 4 and 5) of plate-shaped aluminum current collector plates 72 in which the annular groove 79 has the shape shown in FIG. 6 are designed, and CAE (computer aided engineering) analysis is performed for each sample. The stress analysis was performed. Samples 1 to 3 and 5 have an annular groove 79 formed on the surface facing the insulating holder 32 when the battery 10 is constructed using the current interrupting mechanism 80 provided with the current collector plate 72. An annular groove 79 was formed on the surface opposite to the annular groove forming surfaces 1 to 3 and 5 (that is, the surface facing the electrode body 50 when the battery was constructed). The current collecting plate 72 according to each sample is the same except for the depth of the annular groove 79 (the thickness of the remaining portion), the formation surface of the annular groove 79, the cross-sectional area of the annular groove forming portion, and the interval between the pores 76. Designed to be a parameter.
The annular groove 79 of the current collecting plate 72 according to the sample 1 has a predetermined internal pressure when the battery 10 having the current interrupting mechanism 80 including the current collecting plate 72 reaches a predetermined pressure when a predetermined stress is applied. The annular groove 79 having the same shape as the annular groove 79 formed in the conventional current collector plate 72, and the thickness of the thinnest portion of the remaining portion is reduced to 0. 075 mm. Further, the annular groove 79 of the current collector plate 72 according to the sample 2 has a smaller depth of cut than the annular groove 79 of the sample 1 (that is, the remaining portion is thicker), and is the thinnest of the remaining portions. The thickness of the part was 0.15 mm. In addition, a through-hole (pore 76) having a diameter of 0.06 mm is formed on the bottom surface of the annular groove 79 of the current collector plate 72 according to Samples 3 to 5, and Sample 3 and Sample 4 have the same pore spacing. Thus, Sample 5 was designed so that the pore spacing was wider than Samples 3 and 4. For samples 3 to 5, the thickness of the thinnest portion of the remaining portion was 0.15 mm as in sample 2. FIG. 9 shows a relative ratio of the cross-sectional area of the annular groove forming portion of the current collector plate 72 according to each sample when the cross-sectional area of the annular groove forming portion in Sample 1 is 100%.
各例に係る集電板72について、図7に示すように、当該集電板72を用いた電流遮断機構80を備える電池10を構築した際に絶縁ホルダー32に対向する面が上面となるように配置し、厚肉部78の端部側面を固定し且つ薄肉部74の端部を上方向に押し上げる方向に荷重を負荷したときの応力分布をCAE(computer aided engineering)解析にて応力解析した。サンプル3に係る集電板72の応力解析の結果を図8に示す(当該図8では、応力が集中している箇所を濃い色で示す)。図8に示すように、環状溝79の底面に細孔76を設けたサンプル3では、該細孔76の端部に応力が集中することを確認した。また、ここでは図示していないが、サンプル4及びサンプル5も、サンプル3と同様に、細孔76の端部に応力が集中することを確認した。各サンプルに係る集電板72で生じた最大応力について、サンプル1に係る集電板72において生じた最大応力を100%としたときの相対比を図9に示す。サンプル2に係る集電板72で生じた最大応力はサンプル1で生じた最大応力の0.6倍であり、所定荷重(設定荷重)を負荷しても環状溝79が破断する破断応力には至らなかった。その一方で、環状溝79の底面に細孔76を設けたサンプル3〜5に係る集電板で生じた最大応力はサンプル1で生じた最大応力の0.9〜1.3倍であり、所定荷重(設定荷重)を負荷することで、環状溝79が破断し得る破断応力に達することを確認した。
また、図9に示す通り、サンプル3およびサンプル4に係る集電板72の環状溝形成部分の断面積はサンプル1の集電板の環状溝形成部分の断面積と比較して1.25倍であり、サンプル5に係る集電板72の環状溝形成部分の断面積はサンプル1の集電板72の環状溝形成部分の断面積と比較して1.6倍であった。即ち、各サンプルに係る集電板72について環状溝形成部分のうちの断面積が最も小さい箇所で発生するジュール熱を比較すると、サンプル3およびサンプル4はサンプル1の1/1.25倍(凡そ80%)であり、サンプル5はサンプル1の1/1.6倍(凡そ62%)であった。即ち、環状溝79の底部に細孔76を設けることで、該環状溝形成部分におけるジュール熱の発生を抑制し得ることを確認した。
With respect to the current collector plate 72 according to each example, as shown in FIG. 7, the surface facing the insulating holder 32 becomes the upper surface when the battery 10 including the current interruption mechanism 80 using the current collector plate 72 is constructed. The stress distribution was analyzed by CAE (computer aided engineering) analysis when the load was applied in the direction of fixing the end side surface of the thick portion 78 and pushing the end portion of the thin portion 74 upward. . FIG. 8 shows the result of the stress analysis of the current collector 72 according to the sample 3 (in FIG. 8, the portion where the stress is concentrated is shown in a dark color). As shown in FIG. 8, in the sample 3 in which the pores 76 are provided on the bottom surface of the annular groove 79, it was confirmed that stress was concentrated on the end portions of the pores 76. Further, although not shown here, it was confirmed that stress was concentrated on the ends of the pores 76 in the sample 4 and the sample 5 as in the case of the sample 3. FIG. 9 shows the relative ratio of the maximum stress generated in the current collector plate 72 according to each sample when the maximum stress generated in the current collector plate 72 according to sample 1 is 100%. The maximum stress generated in the current collector 72 according to the sample 2 is 0.6 times the maximum stress generated in the sample 1, and the breaking stress at which the annular groove 79 is broken even when a predetermined load (set load) is applied. It did not come. On the other hand, the maximum stress generated in the current collector plate according to Samples 3 to 5 provided with the pores 76 in the bottom surface of the annular groove 79 is 0.9 to 1.3 times the maximum stress generated in Sample 1. It was confirmed that by applying a predetermined load (set load), the annular groove 79 reached a breaking stress at which the annular groove 79 could break.
Further, as shown in FIG. 9, the cross-sectional area of the annular groove forming portion of the current collecting plate 72 according to Sample 3 and Sample 4 is 1.25 times the cross sectional area of the annular groove forming portion of the current collecting plate of Sample 1. The sectional area of the annular groove forming portion of the current collecting plate 72 according to Sample 5 was 1.6 times that of the annular groove forming portion of the current collecting plate 72 of Sample 1. That is, when comparing the Joule heat generated at the location where the cross-sectional area of the annular groove forming portion of the current collecting plate 72 relating to each sample is the smallest, Sample 3 and Sample 4 are 1 / 1.25 times as large as Sample 1 (approximately 80%), and Sample 5 was 1 / 1.6 times that of Sample 1 (approximately 62%). That is, it was confirmed that the generation of Joule heat at the annular groove forming portion can be suppressed by providing the pores 76 at the bottom of the annular groove 79.
上記のとおり、本発明によると、ここで開示される集電板を使用した電流遮断機構を備える密閉型二次電池(典型的には外形が角形状のリチウム二次電池その他の密閉型二次電池)を提供することができる。かかる集電板は充放電に伴って発生し得るジュール熱による変形(クリープ)および溶断が抑制された集電板であるため、当該集電板を使用した電流遮断機構は、耐熱性に優れ且つ所定のケース内圧(ガス圧)が生じた場合には精度よく電流遮断を実現する信頼性の高い電流遮断機構である。したがって、かかる電流遮断機構を備える密閉型二次電池は、高出力化にともなうハイレート充放電を要求される車両(例えば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。 As described above, according to the present invention, a sealed secondary battery (typically a lithium secondary battery having a square outer shape or other sealed secondary battery having a current interruption mechanism using a current collector plate disclosed herein is used. Battery). Since such a current collector plate is a current collector plate in which deformation (creep) and fusing due to Joule heat that can occur in association with charge and discharge are suppressed, the current interrupting mechanism using the current collector plate is excellent in heat resistance and This is a highly reliable current interrupting mechanism that realizes current interrupting accurately when a predetermined case internal pressure (gas pressure) occurs. Therefore, a sealed secondary battery equipped with such a current interrupting mechanism is a vehicle (for example, a plug-in hybrid vehicle (PHV), a hybrid vehicle (HV), an electric vehicle (EV), etc.) that requires high-rate charging / discharging as the output increases. It is suitable as a driving power source.
以上、本発明の具体例を詳細に説明したが、これらは例示にすぎず、請求の範囲を限定するものではない。請求の範囲に記載の技術には、以上に例示した具体例を様々に変形、変更したものが含まれる。 As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
10 二次電池(リチウムイオン電池)
12 電池ケース
14 ケース本体
16 封口板(蓋体)
18 負極外部端子
20 正極外部端子
22 接続端子
22B 貫通孔
22C 先端部
24 ガスケット
26 絶縁板
28 封口体タブ
30 反転板(電流遮断弁)
30A 中央凹部
32 絶縁ホルダー
50 捲回電極体
52 正極シート
54 セパレータシート
55 捲回コア部
60 正極集電タブ
70 正極内部端子
71 連結部(アーム部)
72 集電板
74 中央薄肉部
74A ガス流通孔
76 細孔
78 厚肉部
78A ガス流通孔
79 環状溝(ノッチ)
80 電流遮断機構
10 Secondary battery (lithium ion battery)
12 Battery case 14 Case body 16 Sealing plate (lid)
18 Negative External Terminal 20 Positive External Terminal 22 Connection Terminal 22B Through Hole 22C Tip 24 Gasket 26 Insulating Plate 28 Sealing Body Tab 30 Reverse Plate (Current Cutoff Valve)
30A Central recessed part 32 Insulation holder 50 Winding electrode body 52 Positive electrode sheet 54 Separator sheet 55 Winding core part 60 Positive electrode current collection tab 70 Positive electrode internal terminal 71 Connection part (arm part)
72 Current Collector Plate 74 Center Thin Wall 74A Gas Flow Hole 76 Fine Hole 78 Thick Wall 78A Gas Flow Hole 79 Annular Groove (Notch)
80 Current interrupt mechanism
Claims (1)
前記電極体を収容する電池ケースと、
前記電池ケースの外面に設けられ、前記電極体の正極および負極とそれぞれ電気的に接続される正極外部端子および負極外部端子と、
前記ケース内の内圧が所定レベルを超えて上昇した際に電流を遮断する電流遮断機構と、を備える密閉型二次電池であって、
前記電流遮断機構は、前記電極体の正極と前記正極外部端子との間または前記電極体の負極と前記負極外部端子との間において、前記正負いずれかの端子と電気的に接続される電流遮断弁と、前記電極体の正負いずれかの電極と電気的に接続されるプレート形状の集電板と、を備えており、
前記集電板は、相対的に薄肉に形成された中央薄肉部と該中央薄肉部の周囲であって相対的に厚肉に形成された厚肉部とから構成されており、且つ、該中央薄肉部の内側において所定の直径で環状に破断用の溝が形成されており、
前記電流遮断弁は、その一部が前記環状溝の内側において前記集電板の中央薄肉部に通電可能に接合されており、
前記ケース内の内圧が所定レベルを超えて上昇した際には、該内圧によって電流遮断弁が前記集電板から離れる方向に変形するとともに前記環状溝の部分で前記集電板の中央薄肉部が破断することによって、前記集電板から前記破断した中央薄肉部を伴う電流遮断弁が離れて電流遮断が実現するように構成されており、
前記薄肉部のうちの前記環状溝の底面に該当する部分には、当該環状溝の底面よりも凹んだ細孔が該溝の底面に沿って複数形成されている、密閉型二次電池。
An electrode body comprising a positive electrode and a negative electrode;
A battery case that houses the electrode body;
A positive external terminal and a negative external terminal provided on the outer surface of the battery case and electrically connected to the positive electrode and the negative electrode of the electrode body, respectively;
A sealed secondary battery comprising a current interrupting mechanism that interrupts current when the internal pressure in the case rises above a predetermined level,
The current interruption mechanism is an electric current interruption electrically connected to either the positive or negative terminal between the positive electrode of the electrode body and the positive external terminal or between the negative electrode of the electrode body and the negative external terminal. A valve and a plate-shaped current collector electrically connected to either the positive or negative electrode of the electrode body,
The current collector plate is composed of a central thin portion formed relatively thin and a thick portion formed around the central thin portion and relatively thick, and the center A breaking groove is formed in an annular shape with a predetermined diameter inside the thin portion,
A part of the current cutoff valve is joined to the central thin part of the current collector plate inside the annular groove so as to be energized,
When the internal pressure in the case rises above a predetermined level, the current shut-off valve is deformed in a direction away from the current collector plate by the internal pressure, and the central thin portion of the current collector plate is at the annular groove portion. By breaking, the current cut-off valve with the broken central thin portion is separated from the current collector plate, and the current cut-off is configured to be realized.
A sealed secondary battery in which a plurality of pores recessed from the bottom surface of the annular groove are formed in a portion corresponding to the bottom surface of the annular groove in the thin portion, along the bottom surface of the groove.
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JP2014261968A JP2016122581A (en) | 2014-12-25 | 2014-12-25 | Hermetically sealed secondary battery |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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JP2014261968A JP2016122581A (en) | 2014-12-25 | 2014-12-25 | Hermetically sealed secondary battery |
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JP2016122581A true JP2016122581A (en) | 2016-07-07 |
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2014
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