JP5171441B2 - Sealed secondary battery - Google Patents

Sealed secondary battery Download PDF

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JP5171441B2
JP5171441B2 JP2008175598A JP2008175598A JP5171441B2 JP 5171441 B2 JP5171441 B2 JP 5171441B2 JP 2008175598 A JP2008175598 A JP 2008175598A JP 2008175598 A JP2008175598 A JP 2008175598A JP 5171441 B2 JP5171441 B2 JP 5171441B2
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injection port
battery
sleeve
liquid injection
secondary battery
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JP2010015867A (en
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幹男 小熊
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Vehicle Energy Japan Inc
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Hitachi Vehicle Energy Ltd
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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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Description

本発明は密閉型二次電池に係り、特に、正負極がセパレータを介して配置された電極群と、電極群を浸潤する電解液と、電極群および電解液を収容する電池容器と、電池容器に装着された安全弁とを備えた密閉型二次電池に関する。   The present invention relates to a sealed secondary battery, and in particular, an electrode group in which positive and negative electrodes are arranged via a separator, an electrolyte solution infiltrating the electrode group, a battery container containing the electrode group and the electrolyte solution, and a battery container The present invention relates to a sealed secondary battery including a safety valve mounted on the battery.

従来、電気自動車や据置型電力供給装置などの電源として用いられる大電流充放電用途の密閉型二次電池では、一般に、正負極がセパレータを介して配置された電極群が電解液に浸潤され、電池容器内に収容されている。電池容器には内圧上昇時にガスを放出する安全弁が装着されており、安全弁は、電解液を注入するための注液口とは別個に設けられている。   Conventionally, in a sealed secondary battery for large current charge and discharge used as a power source for an electric vehicle or a stationary power supply device, generally, an electrode group in which positive and negative electrodes are arranged via a separator is infiltrated into an electrolyte solution, Housed in a battery container. The battery container is equipped with a safety valve that releases gas when the internal pressure rises, and the safety valve is provided separately from the liquid injection port for injecting the electrolyte.

注液口は電解液を注入後にネジを用いて塞ぐか、あるいは円形または球形の金属片（以下、ネジを含めてこれらを閉塞部材という。）を溶接して塞ぐ方法などが採用されている（例えば、特許文献１参照）。一方、安全弁は、電池容器自体に部分的な脆弱部を設けることが難しいため、予め脆弱部を加工した別部品の弁体を、電池容器に形成された開口に電極群や電解液を収容する前に溶接することが一般的である（例えば、特許文献２参照）。   The injection port may be closed with a screw after injecting an electrolytic solution, or may be closed by welding a circular or spherical metal piece (hereinafter referred to as a closing member including a screw) (see FIG. For example, see Patent Document 1). On the other hand, since it is difficult to provide a partial fragile part in the battery container itself, the safety valve accommodates the electrode body and the electrolytic solution in an opening formed in the battery container with a separate valve body processed in advance. It is common to weld before (for example, refer patent document 2).

特開２００５−１５８２６７号公報JP 2005-158267 A 特開２００２−０５０３３８号公報JP 2002-050338 A

しかしながら、上述した従来の構造では、注液口を封口する封口部材と安全弁にそれぞれ別の部品を必要とするためコスト低減の妨げとなるのみならず、溶接工程でも不良が発生しやすいため、安定した量産を阻害する要因となっている。また、有機電解液（非水電解液）を用いた二次電池では、注液口を溶接で塞ぐ際に電解液への引火のおそれが排除できず、製造上の安全性の面でも十分な配慮が必要であった。   However, the above-described conventional structure requires separate parts for the sealing member that seals the liquid injection port and the safety valve, which not only hinders cost reduction, but also causes defects in the welding process. This is a factor that hinders mass production. In addition, in secondary batteries using organic electrolyte (non-aqueous electrolyte), there is no possibility of igniting the electrolyte when the injection hole is closed by welding, which is sufficient in terms of manufacturing safety. Consideration was necessary.

本発明は上記事案に鑑み、コスト低減および生産性向上が可能で電解液への引火を防止できる密閉型二次電池を提供することを課題とする。   An object of the present invention is to provide a sealed secondary battery capable of reducing cost and improving productivity and preventing ignition of an electrolyte solution in view of the above-described case.

上記課題を解決するために、本発明は、密閉型二次電池であって、正負極がセパレータを介して配置された電極群と、前記電極群を浸潤する電解液と、前記電解液を注液するための注液口が形成され、前記電極群および電解液を収容する電池容器と、前記電池容器の注液口を密閉する安全弁とを備え、前記安全弁は、前記電池容器の注液口に、一側端部が拡径された芯金と該芯金を包み込む金属製有底筒状部材とを有する弁体を予め挿入しておき、前記芯金を引き抜くことで前記筒状部材を内側から拡径して前記電池容器の注液口に装着されたものであることを特徴とする。   In order to solve the above-described problems, the present invention provides a sealed secondary battery, in which an electrode group in which positive and negative electrodes are arranged via a separator, an electrolyte solution infiltrating the electrode group, and the electrolyte solution are injected. A liquid injection port for forming a liquid is formed, the battery container containing the electrode group and the electrolyte, and a safety valve that seals the liquid injection port of the battery container, the safety valve being a liquid injection port of the battery container In addition, a valve body having a core metal whose one end is enlarged in diameter and a metal bottomed cylindrical member that wraps the core metal is inserted in advance, and the cylindrical member is removed by pulling out the core metal. The diameter is increased from the inside and is mounted on the liquid injection port of the battery container.

本発明では、電池容器に電解液を注液するための注液口が形成されており、注液口を介して電解液の注液後、注液口に、一側端部が拡径された芯金と該芯金を包み込む金属製有底筒状部材とを有する弁体を予め挿入しておき、芯金を引き抜くことで筒状部材が内側から拡径されて弁体が注液口に装着され、芯金が引き抜かれた弁体すなわち安全弁により注液口が密閉される。このため、注液口を塞ぐ閉塞部材と安全弁とをそれぞれ別部品とする必要がなくコスト低減を図ることができ、安全弁を溶接する必要がなく生産性を高めることができるとともに、電解液への引火のおそれもなく安全性を高めることができる。   In the present invention, a liquid injection port for injecting an electrolytic solution into the battery container is formed, and after injection of the electrolytic solution through the liquid injection port, one end of the diameter is expanded in the liquid injection port. A valve body having a metal core and a metal bottomed cylindrical member that wraps the metal core is inserted in advance, and the diameter of the cylindrical member is expanded from the inside by pulling out the metal core, so that the valve body is a liquid inlet. The liquid injection port is hermetically sealed by a valve body, that is, a safety valve that is attached to the metal core and from which the metal core is pulled out. For this reason, it is not necessary to separate the closing member and the safety valve for closing the liquid injection port, so that the cost can be reduced, the safety valve need not be welded, the productivity can be improved, and the electrolyte solution can be improved. Safety can be improved without fear of ignition.

本発明において、筒状部材の硬度が芯金の硬度より小さいことが好ましい。弁体には、芯金の拡径された一側端部近傍に脆弱部が形成されていてもよい。   In this invention, it is preferable that the hardness of a cylindrical member is smaller than the hardness of a metal core. In the valve body, a weakened portion may be formed in the vicinity of one end portion of the core metal whose diameter has been increased.

また、電池の気密性を向上させるために、安全弁と電池容器の注液口との間に熱可塑性樹脂製スリーブを介在させることがより好ましい。この場合、安全弁は、電池容器の注液口にスリーブと弁体とを予め挿入しておき、芯金を引き抜くことで筒状部材を内側から拡径するとともにスリーブを圧縮して電池容器の注液口に装着されることが好ましい。注液口は円形状であり、筒状部材は円筒状であり、スリーブは無底円筒状であってもよい。また、スリーブは電池容器に当接する鍔部を有し、筒状部材はスリーブの鍔部に当接する鍔部を有していてもよい。筒状部材を拡径した後の弁体の外径は、電池容器の注液口の内径より小さいことが好ましい。また、スリーブの圧縮率は６０％未満であることが好ましい。   In order to improve the air tightness of the battery, it is more preferable to interpose a thermoplastic resin sleeve between the safety valve and the liquid container inlet. In this case, the safety valve inserts the sleeve and the valve body into the liquid container inlet beforehand, and pulls out the core bar to expand the diameter of the cylindrical member from the inside and compress the sleeve to inject the battery container. It is preferable to attach to the liquid port. The liquid injection port may be circular, the cylindrical member may be cylindrical, and the sleeve may be bottomless cylindrical. In addition, the sleeve may have a flange that contacts the battery container, and the cylindrical member may have a flange that contacts the flange of the sleeve. It is preferable that the outer diameter of the valve body after expanding the cylindrical member is smaller than the inner diameter of the liquid injection port of the battery container. The compression rate of the sleeve is preferably less than 60%.

本発明によれば、注液口を塞ぐ閉塞部材と安全弁とをそれぞれ別部品とする必要がなくコスト低減を図ることができ、安全弁を溶接する必要がなく生産性を高めることができるとともに、電解液への引火のおそれもなく安全性を高めることができる、という効果を得ることができる。   According to the present invention, it is not necessary to separately form a closing member for closing the liquid injection port and a safety valve, so that the cost can be reduced, the safety valve need not be welded, and productivity can be improved. The effect that safety can be improved without fear of ignition of the liquid can be obtained.

以下、図面を参照して、本発明を、ハイブリッド自動車用の電源となる扁平密閉型リチウムイオン電池に適用した実施の形態について説明する。   Hereinafter, an embodiment in which the present invention is applied to a flat sealed lithium ion battery serving as a power source for a hybrid vehicle will be described with reference to the drawings.

（構成）
＜電池＞
図１に示すように、本実施形態のリチウムイオン電池３０（以下、単に電池３０という。）は、電池容器としての、断面扁平円形状でニッケルメッキが施されたスチール製の電池缶１７および扁平円盤状の電池蓋２２内に、後述する電極群および非水電解液が収容されている。電池蓋２２の一側には正極出力端子２３が突設されており、他側には安全弁２０が装着されている。電池３０は、電池缶１７が負極性を有し、電池蓋２２（正極出力端子２３）が正極性を有している。電池缶１７の底面を除く側周部は図示しないシュリンクチューブで被覆されている。 (Constitution)
<Battery>
As shown in FIG. 1, a lithium ion battery 30 (hereinafter simply referred to as a battery 30) of the present embodiment is a battery case 17 and a flat battery case 17 made of nickel and plated in a flat circular shape as a battery container. An electrode group and a non-aqueous electrolyte described later are accommodated in a disk-shaped battery lid 22. A positive output terminal 23 projects from one side of the battery cover 22 and a safety valve 20 is attached to the other side. In the battery 30, the battery can 17 has a negative polarity, and the battery lid 22 (positive electrode output terminal 23) has a positive polarity. The side periphery except the bottom surface of the battery can 17 is covered with a shrink tube (not shown).

図２に示すように、電池缶１７と電池蓋２２で構成される電池容器の内部には、帯状の正負極板がセパレータを介して捲回された電極群１６が収容されている。電極群１６の捲回中心には、ポリプロピレン製で中空扁平円筒状の軸芯１１が使用されている。   As shown in FIG. 2, an electrode group 16 in which a band-like positive and negative electrode plate is wound through a separator is accommodated in a battery container composed of a battery can 17 and a battery lid 22. A hollow flat cylindrical shaft core 11 made of polypropylene is used at the winding center of the electrode group 16.

電極群１６の上側には、正極板からの電位を集電するための正極集電リング１４が配置されている。正極集電リング１４は、扁平ドーナツ盤状に形成されており、軸芯１１の上端部に固定されている。正極集電リング１４の周囲から一体に張り出した鍔部周面付近には正極板から導出された正極リード片１２が変形され集合されており、正極リード片１２と鍔部周面とが超音波溶接で接合されている。正極集電リング１４の鍔部周面全周には、絶縁被覆が施されている。正極集電リング１４の上方には、電池缶１７を封口するための電池蓋２２が配置されている。   On the upper side of the electrode group 16, a positive electrode current collecting ring 14 for collecting a potential from the positive electrode plate is disposed. The positive electrode current collecting ring 14 is formed in a flat donut disk shape, and is fixed to the upper end portion of the shaft core 11. The positive electrode lead pieces 12 led out from the positive electrode plate are deformed and assembled in the vicinity of the collar peripheral surface integrally projecting from the periphery of the positive electrode current collecting ring 14, and the positive electrode lead pieces 12 and the collar peripheral surface are ultrasonic. It is joined by welding. An insulation coating is applied to the entire circumference of the collar peripheral surface of the positive electrode current collecting ring 14. A battery lid 22 for sealing the battery can 17 is disposed above the positive electrode current collecting ring 14.

電池蓋２２は、アルミニウム製の蓋ケースと、上述した正極出力端子２３が突設されニッケルメッキが施されたスチール製の蓋キャップとで構成されており、これらが積層され蓋ケースの周縁部をカシメ固定することによって組立てられている。電池蓋２２は、蓋ケースが電極群１６側に配置され、蓋キャップが外側に配置されている。なお、電池缶１７および電池蓋２２のいずれにもニッケルメッキが施されていることから、電池３０は、同種の金属（ニッケル）を接続部材として直列接続ないし直並列接続をすることができる。   The battery lid 22 includes an aluminum lid case and a steel lid cap provided with the above-described positive electrode output terminal 23 protruding and nickel-plated, and these are laminated to form a peripheral portion of the lid case. It is assembled by caulking and fixing. The battery lid 22 has a lid case disposed on the electrode group 16 side and a lid cap disposed outside. Since both the battery can 17 and the battery lid 22 are nickel-plated, the battery 30 can be connected in series or in series-parallel using the same kind of metal (nickel) as a connecting member.

電池蓋２２の正極出力端子２３が突設された反対側には、非水電解液を注液するとともに、安全弁２０を装着するため円形状の注液口２２Ａ（図３参照）が形成されている（図２では、電解液を注液し安全弁２０を装着した後の電池完成状態が示されている。）。正極集電リング１４の上部には、予め複数枚のアルミニウム製リボンを重ね合わせて構成した正極リード１９の一端が接合されており、正極リード１９の他端は電池蓋２２の下面に接合されている。   On the opposite side of the battery cover 22 where the positive electrode output terminal 23 protrudes, a non-aqueous electrolyte solution is injected, and a circular injection port 22A (see FIG. 3) is formed for mounting the safety valve 20. (In FIG. 2, the battery is in a completed state after the electrolytic solution is injected and the safety valve 20 is mounted). One end of a positive electrode lead 19 formed by previously stacking a plurality of aluminum ribbons is bonded to the upper portion of the positive electrode current collecting ring 14, and the other end of the positive electrode lead 19 is bonded to the lower surface of the battery lid 22. Yes.

一方、電極群１６の下側には、負極板からの電位を集電するための負極集電リング１５が配置されている。負極集電リング１５は、扁平ドーナツ盤状に形成されており、軸芯１１の下端部に固定されている。負極集電リング１５の周面には、正極集電リング１４と正極リード片１２との接続操作と同様に、負極板から導出された負極リード片１３が超音波溶接で接合されている。負極集電リング１５の下側には、予め電気的導通のための負極リード板１８が溶接されており、負極リード板１８は負極外部端子を兼ねる電池缶１７の内底面に溶接されている。   On the other hand, a negative electrode current collecting ring 15 for collecting the electric potential from the negative electrode plate is disposed below the electrode group 16. The negative electrode current collecting ring 15 is formed in a flat donut disk shape, and is fixed to the lower end portion of the shaft core 11. Similarly to the connection operation between the positive electrode current collector ring 14 and the positive electrode lead piece 12, the negative electrode lead piece 13 led out from the negative electrode plate is joined to the peripheral surface of the negative electrode current collector ring 15 by ultrasonic welding. A negative electrode lead plate 18 for electrical conduction is welded to the lower side of the negative electrode current collecting ring 15 in advance, and the negative electrode lead plate 18 is welded to the inner bottom surface of the battery can 17 that also serves as a negative electrode external terminal.

正極リード１９は電池缶１７内に折りたたむようにして収容されており、電池蓋２２は電池缶１７の上部にＥＰＤＭ樹脂製ガスケット２１を介してカシメ固定されている。また、電池缶１７内には、電極群１６全体を浸潤可能な量の図示しない非水電解液が注液されている。非水電解液には、例えば、有機溶媒のエチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＭＣ）とを体積比１：２の割合で混合した混合溶媒中へ六フッ化リン酸リチウム（ＬｉＰＦ６）を１モル／リットルの濃度で溶解したものを用いることができる。 The positive electrode lead 19 is accommodated in the battery can 17 so as to be folded, and the battery lid 22 is fixed by caulking to the upper part of the battery can 17 via an EPDM resin gasket 21. Further, a non-aqueous electrolyte solution (not shown) in an amount capable of infiltrating the entire electrode group 16 is injected into the battery can 17. In the non-aqueous electrolyte, for example, lithium hexafluorophosphate (LiPF 6 ) is mixed into a mixed solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC), which are organic solvents, are mixed at a volume ratio of 1: 2. Those dissolved at a concentration of 1 mol / liter can be used.

電極群１６は、正極板と負極板とが、これら両極板が直接接触しないように、ポリエチレン製の微多孔性セパレータを介して軸芯１１の周りに捲回されている。正極板および負極板からそれぞれ導出された正極リード片１２および負極リード片１３は、それぞれ電極群１６の互いに反対側の両端面に配置されている。   In the electrode group 16, the positive electrode plate and the negative electrode plate are wound around the shaft core 11 via a microporous separator made of polyethylene so that the two electrode plates do not directly contact each other. The positive electrode lead piece 12 and the negative electrode lead piece 13 led out from the positive electrode plate and the negative electrode plate, respectively, are disposed on the opposite end surfaces of the electrode group 16.

電極群１６を構成する正極板は、正極活物質に、例えば、マンガン酸リチウム等のリチウム遷移金属複酸化物が用いられる。正極板は、帯状のアルミニウム箔（正極集電体）に正極合剤が略均一に塗着されている。正極合剤には、リチウム遷移金属複酸化物の粉末、導電材の炭素粉末および結着材のポリフッ化ビニリデン（ＰＶＤＦ）が混合されている。正極合剤をアルミニウム箔に塗布するときには、例えば、溶媒のＮ−メチルピロリドン（ＮＭＰ）で粘度調整される。アルミニウム箔の長手方向に沿う一側には、正極合剤の未塗布部が残されており、未塗布部を櫛状に切り欠くことで正極リード片１２が形成されている。正極板は、乾燥後、プレス成形され、裁断されている。   The positive electrode plate constituting the electrode group 16 uses, for example, a lithium transition metal double oxide such as lithium manganate as the positive electrode active material. In the positive electrode plate, a positive electrode mixture is applied substantially uniformly to a strip-shaped aluminum foil (positive electrode current collector). The positive electrode mixture is mixed with powder of lithium transition metal double oxide, carbon powder of conductive material, and polyvinylidene fluoride (PVDF) of binder. When the positive electrode mixture is applied to the aluminum foil, for example, the viscosity is adjusted with N-methylpyrrolidone (NMP) as a solvent. An uncoated portion of the positive electrode mixture is left on one side along the longitudinal direction of the aluminum foil, and the positive electrode lead piece 12 is formed by cutting the uncoated portion into a comb shape. The positive electrode plate is press-molded and cut after being dried.

一方、負極板は、負極活物質に、例えば、非晶質炭素等の炭素材が用いられる。負極板は、帯状の銅箔（負極集電体）に負極合剤が略均一に塗着されている。負極合剤には、非晶質炭素の粉末および結着材のＰＶＤＦが混合されている。負極合剤を銅箔に塗布するときには、正極板と同様に例えば、溶媒のＮＭＰで粘度調整される。銅箔の長手方向に沿う一側には、正極板と同様に負極リード片１３が形成されている。負極板は、乾燥後、プレス成形され、裁断されている。   On the other hand, for the negative electrode plate, for example, a carbon material such as amorphous carbon is used as the negative electrode active material. In the negative electrode plate, a negative electrode mixture is applied substantially uniformly to a strip-shaped copper foil (negative electrode current collector). The negative electrode mixture is mixed with amorphous carbon powder and binder PVDF. When the negative electrode mixture is applied to the copper foil, the viscosity is adjusted with NMP as a solvent, for example, in the same manner as the positive electrode plate. On one side along the longitudinal direction of the copper foil, a negative electrode lead piece 13 is formed in the same manner as the positive electrode plate. The negative electrode plate is press-molded and cut after being dried.

なお、電池３０の定格容量は１０Ａｈである。また、電池３０内の電極群１６から正負極外部端子までの集電部材および接続部材は、定格容量に対する１時間率放電電流の５倍以上の電流を通電可能である。   The rated capacity of the battery 30 is 10 Ah. Further, the current collecting member and the connecting member from the electrode group 16 in the battery 30 to the positive and negative external terminals can be energized with a current that is five times or more the hourly discharge current with respect to the rated capacity.

＜安全弁の構成＞
図３に示すように、安全弁２０は、弁体１０とガスケットとして機能するスリーブ４とで構成されている。弁体１０は筒状部材１と芯金２とを有している。筒状部材１は鍔部３を有する金属製の有底円筒状で、内部に、一側端部（先端部）に拡径された大径部５を有し、その近傍に脆弱部６を形成した金属製の芯金２が包み込まれるように配置されている。筒状部材１は芯金２より硬度の小さい（軟らかい）材質で構成されている。スリーブ４は熱可塑性樹脂で鍔部を有する無底円筒状を呈しており、円筒部８の内径は筒状部材１の外形とほぼ等しく、外径は電池蓋２２に形成された注液口２２Ａの内径にほぼ等しい。 <Composition of safety valve>
As shown in FIG. 3, the safety valve 20 includes a valve body 10 and a sleeve 4 that functions as a gasket. The valve body 10 has a cylindrical member 1 and a cored bar 2. The cylindrical member 1 has a bottomed cylindrical shape made of metal having a flange 3, and has a large-diameter portion 5 whose diameter is enlarged at one end portion (tip portion) inside, and a fragile portion 6 in the vicinity thereof. It arrange | positions so that the formed metal core metal 2 may be wrapped. The cylindrical member 1 is made of a material having a lower hardness (softer) than the core metal 2. The sleeve 4 is made of a thermoplastic resin and has a bottomless cylindrical shape having a flange portion. The inner diameter of the cylindrical portion 8 is substantially equal to the outer shape of the cylindrical member 1, and the outer diameter is a liquid injection port 22 </ b> A formed in the battery lid 22. Is approximately equal to the inner diameter of

＜安全弁の取り付け＞
電池蓋２２に形成された注液口２２Ａから電解液を注入した後、注液口２２Ａにスリーブ４と弁体１０を挿入する。このとき、スリーブ４の鍔部は電池蓋２２の上面に当接し、筒状部材１の鍔部３（底面）はスリーブ４の鍔部（上面）に当接するため、両者は電池蓋２２で支持され電池缶１７の内部に落下することはない。図３はこのときの状態を示している。 <Installation of safety valve>
After injecting the electrolyte from the injection port 22A formed in the battery lid 22, the sleeve 4 and the valve body 10 are inserted into the injection port 22A. At this time, the collar portion of the sleeve 4 abuts on the upper surface of the battery lid 22, and the collar portion 3 (bottom surface) of the tubular member 1 abuts on the collar portion (upper surface) of the sleeve 4. Then, it does not fall into the battery can 17. FIG. 3 shows the state at this time.

次いで、筒状部材１の鍔部３を治具（不図示）により電池３０本体（電池蓋２２）側に押圧する。この状態で芯金２の他側端部（露出した部分）をグリッパ（不図示）で挟んで上方に引き抜くと、芯金２より硬度の小さい（軟らかい）材質で作られている筒状部材１は、芯金２の一側端部の大径部５が上方に移動するため、図４に示すように変形し、内径および外径が拡張（拡径）される。このとき、スリーブ４の円筒部８が圧縮されて筒状部材１と電池蓋２２とが密着し電池２０が密封される。芯金２には脆弱部６が形成されているので、最後にこの部分を破断して分離排除する。このため、芯金２の大径部５は筒状部材１の内部に残り、芯金２が引き抜かれた弁体１０が安全弁２０となる。   Next, the flange 3 of the cylindrical member 1 is pressed toward the battery 30 main body (battery cover 22) side by a jig (not shown). In this state, when the other side end (exposed portion) of the cored bar 2 is sandwiched between grippers (not shown) and pulled upward, the cylindrical member 1 made of a material having a lower hardness (softer) than the cored bar 2 Since the large-diameter portion 5 at one end portion of the core metal 2 moves upward, it is deformed as shown in FIG. 4, and the inner diameter and the outer diameter are expanded (expanded). At this time, the cylindrical portion 8 of the sleeve 4 is compressed, the tubular member 1 and the battery lid 22 are brought into close contact with each other, and the battery 20 is sealed. Since the fragile portion 6 is formed in the cored bar 2, this portion is finally broken and separated and removed. For this reason, the large-diameter portion 5 of the core metal 2 remains inside the cylindrical member 1, and the valve body 10 from which the core metal 2 is pulled out becomes the safety valve 20.

（安全弁の動作）
次に、本実施形態の電池３０の安全弁２０の動作について説明する。 (Safety valve operation)
Next, operation | movement of the safety valve 20 of the battery 30 of this embodiment is demonstrated.

上記のように取り付けられた筒状部材１（弁体１０）の外径は、電池蓋２２に形成された注液口２２Ａの内径よりは小さく作られている。このため、万一過充電などの異常によってガスが発生し、電池３０の内圧が上昇すると、図５に示すように、弁体１０はスリーブ４との摩擦力に抗して上方に移動して行き、ついにはスリーブ４から抜け出て、内部のガスが放出される。このため、電池容器の破裂を防ぐ安全弁として機能する。   The outer diameter of the cylindrical member 1 (valve element 10) attached as described above is made smaller than the inner diameter of the liquid injection port 22 </ b> A formed in the battery lid 22. Therefore, if gas is generated due to an abnormality such as overcharge and the internal pressure of the battery 30 increases, the valve body 10 moves upward against the frictional force with the sleeve 4 as shown in FIG. Finally, it escapes from the sleeve 4 and the gas inside is released. For this reason, it functions as a safety valve that prevents the battery container from bursting.

圧力上昇がわずかで、弁体１０が抜けるところまではいかない場合でも、弁体１０が浮き上がることによって内圧上昇を知ることができ、いわゆるインジケータとしても機能する。従って、例えば、弁体１０の上方にリミットスイッチの検知レバーを配置すれば、内圧が上昇したときに、電気的に警報を発することも可能となる。   Even when the pressure rise is slight and the valve body 10 does not come off, the valve body 10 can be lifted to know the internal pressure rise, and also functions as a so-called indicator. Therefore, for example, if a detection lever of a limit switch is arranged above the valve body 10, an alarm can be issued electrically when the internal pressure rises.

安全弁としての作動圧（弁体１０が抜けるときの圧力）は、スリーブ４の圧縮率を調節することによって変えることができる。しかし、スリーブ４は熱可塑性樹脂で作られているので、あまり圧縮率を高くすると、時間の経過につれて亀裂を生ずるおそれがある。このため、ＰＰやＰＦＡなどの一般的な熱可塑性樹脂を用いるときは、最大でも圧縮率を６０％未満に抑えることが望ましい。このためには、拡径後の弁体１０の外径と、電池蓋２２に形成された注液口２２Ａの内径との差が、スリーブ４の円筒部８の肉厚を越えないように設定することが好ましい。   The operating pressure as the safety valve (pressure when the valve body 10 is released) can be changed by adjusting the compression rate of the sleeve 4. However, since the sleeve 4 is made of a thermoplastic resin, if the compression rate is too high, there is a risk that cracks will occur over time. For this reason, when using general thermoplastic resins, such as PP and PFA, it is desirable to suppress a compression rate to less than 60% at the maximum. For this purpose, the difference between the outer diameter of the valve body 10 after the diameter expansion and the inner diameter of the liquid injection port 22A formed in the battery lid 22 is set so as not to exceed the wall thickness of the cylindrical portion 8 of the sleeve 4. It is preferable to do.

（作用等）
次に、本実施形態の電池３０の作用等について、安全弁２０の作用等を中心に説明する。 (Action etc.)
Next, the operation and the like of the battery 30 of the present embodiment will be described focusing on the operation and the like of the safety valve 20.

本実施形態の安全弁２０は、電池容器の一部としての電池蓋２２の注液口２２Ａにスリーブ４と弁体１０とを予め挿入しておき、芯金２を引き抜くことで筒状部材１を内側から拡径するとともにスリーブ４の円筒部８を圧縮して電池蓋２２の注液口２２Ａに装着されたものである。このため、従来のように注液口を塞ぐ閉塞部材と安全弁とをそれぞれ別部品とする必要がなくコスト低減を図ることができ、安全弁２０を溶接する必要がなく生産性を高めることができるとともに、非水電解液への引火のおそれもなく安全性を高めることができる。   In the safety valve 20 of the present embodiment, the sleeve 4 and the valve body 10 are inserted in advance into the injection port 22A of the battery lid 22 as a part of the battery container, and the core member 2 is pulled out to remove the cylindrical member 1. The diameter is expanded from the inside and the cylindrical portion 8 of the sleeve 4 is compressed and attached to the liquid injection port 22 </ b> A of the battery lid 22. For this reason, it is not necessary to separate the closing member and the safety valve for closing the liquid injection port as in the conventional case, and the cost can be reduced, and the safety valve 20 is not required to be welded and the productivity can be improved. In addition, safety can be improved without fear of ignition of the non-aqueous electrolyte.

なお、本実施形態では、電池３０の気密性を確保するために、スリーブ４を例示したが、本発明はこのスリーブ４を必須とするものではない。すなわち、安全弁は、電池蓋２２の注液口２２Ａに弁体１０を予め挿入しておき、芯金２を引き抜くことで筒状部材１の内側から拡径して電池蓋２２の注液口２２Ａに直接装着されるようにしてもよい。   In the present embodiment, the sleeve 4 is illustrated in order to ensure the airtightness of the battery 30, but the present invention does not require the sleeve 4. That is, the safety valve inserts the valve body 10 into the liquid injection port 22A of the battery lid 22 in advance and withdraws the cored bar 2 to expand the diameter from the inside of the cylindrical member 1 to the liquid injection port 22A of the battery lid 22. You may make it attach directly to.

また、本実施形態では、電池蓋２２に形成された円形状の注液口２２Ａ、有底円筒状の筒状部材１、円筒状のスリーブ４を例示したが、本発明はこれに制限されるものではない。例えば、安全弁は電池缶１７の任意の箇所に形成されていてもよい。また、注液口は例えば楕円ないし長円状、四角形、多角形等の任意の形状を有しており、スリーブ４や弁体１０は注液口の形状に応じた形状とするようにしてもよい。   Further, in the present embodiment, the circular liquid injection port 22A formed in the battery lid 22, the cylindrical member 1 with the bottomed cylindrical shape, and the cylindrical sleeve 4 are illustrated, but the present invention is limited to this. It is not a thing. For example, the safety valve may be formed at any location of the battery can 17. Further, the liquid injection port has an arbitrary shape such as an ellipse, an oval, a quadrangle, or a polygon, and the sleeve 4 and the valve body 10 may have a shape corresponding to the shape of the liquid injection port. Good.

さらに、本実施形態では、扁平円筒型電池を例示したが、本発明はこれに限ることなく、例えば、円柱型（円筒型）電池、角型電池にも適用可能である。また、電極群も捲回式のものに限らず、セパレータを介して正負極を積層したタイプの電池にも適用可能である。   Furthermore, in the present embodiment, a flat cylindrical battery is illustrated, but the present invention is not limited to this, and is applicable to, for example, a columnar (cylindrical) battery and a square battery. Further, the electrode group is not limited to a wound type, and can be applied to a battery of a type in which positive and negative electrodes are stacked via a separator.

実施形態の電池３０に従って実施例の電池を作製し、安全弁２０としての作動の安定性を調べた。実施例では、筒状部材１の材質をアルミニウム合金Ａ１０５０、芯金２の材質をＳＵＳ３０４、スリーブ４の材質をＰＦＡとした。また、スリーブ４の圧縮率を、電池蓋２２に形成された注液口２２Ａの内径とスリーブ４の肉厚を変えて調節した。スリーブ４の圧縮率を１０％から７０％まで変えた電池をそれぞれ５０個ずつ作製し、１ＣＡの充電電流で過充電状態とした。安全弁２０の作動圧は、電池蓋２２の一部にもうひとつの穴をあけ、この穴に圧力センサを取付けて測定した。結果を下表１に示す。   The battery of the example was manufactured according to the battery 30 of the embodiment, and the stability of the operation as the safety valve 20 was examined. In the embodiment, the material of the cylindrical member 1 is aluminum alloy A1050, the material of the cored bar 2 is SUS304, and the material of the sleeve 4 is PFA. Further, the compression ratio of the sleeve 4 was adjusted by changing the inner diameter of the liquid injection port 22 </ b> A formed in the battery lid 22 and the thickness of the sleeve 4. Fifty batteries, each having a compression ratio of the sleeve 4 changed from 10% to 70%, were manufactured and overcharged with a charging current of 1 CA. The operating pressure of the safety valve 20 was measured by making another hole in a part of the battery lid 22 and attaching a pressure sensor to this hole. The results are shown in Table 1 below.

Figure 0005171441
Figure 0005171441

実施した範囲では、電池容器の破裂や発煙、発火に至ったものはなく、安全弁としてはいずれも有効であったが、スリーブ４の圧縮率が６０％以上のものでは、弁体１０の取り付けから１０００時間経過後に亀裂を生じたものがあった。亀裂を生ずると、電池の気密は保てなくなり、電池性能の急速な劣化を招くこととなる。このため、スリーブ４の圧縮率は６０％未満に抑えることが望ましいことが判明した。   In the implemented range, there was no battery container that ruptured, smoked, or ignited, and all were effective as safety valves. However, when the compression rate of the sleeve 4 was 60% or more, the valve body 10 was attached. Some had cracked after 1000 hours. When cracks occur, the battery cannot be kept airtight, leading to rapid deterioration of battery performance. For this reason, it turned out that it is desirable to suppress the compression rate of the sleeve 4 to less than 60%.

本発明はコスト低減および生産性向上が可能で電解液への引火を防止できる密閉型二次電池を提供するものであるため、密閉型二次電池の製造、販売に寄与するので、産業上の利用可能性を有する。   Since the present invention provides a sealed secondary battery capable of reducing costs and improving productivity and preventing ignition of the electrolyte, it contributes to the manufacture and sale of sealed secondary batteries. Has availability.

本発明が適用可能な実施形態のリチウムイオン電池の外観斜視図である。It is an external appearance perspective view of the lithium ion battery of embodiment which can apply this invention. 実施形態のリチウムイオン電池の断面図である。It is sectional drawing of the lithium ion battery of embodiment. 実施形態のリチウムイオン電池の注液口に装着される安全弁の筒状部材拡径前の状態を示す断面図である。It is sectional drawing which shows the state before the cylindrical member diameter expansion of the safety valve with which the injection hole of the lithium ion battery of embodiment is attached. 実施形態のリチウムイオン電池の注液口に装着された安全弁の筒状部材拡径後の状態を示す断面図である。It is sectional drawing which shows the state after the cylindrical member diameter expansion of the safety valve with which the injection hole of the lithium ion battery of embodiment was mounted | worn. 実施形態のリチウムイオン電池の内圧上昇時の安全弁の状態を示す断面図である。It is sectional drawing which shows the state of the safety valve at the time of the internal pressure rise of the lithium ion battery of embodiment.

符号の説明Explanation of symbols

１ 筒状部材
２ 芯金
３ 鍔部
４ スリーブ
５ 大径部
６ 脆弱部
１０ 弁体
１６ 電極群
１７ 電池缶（電池容器の一部）
２０ 安全弁
２２ 電池蓋（電池容器の一部）
２２Ａ 注液口
３０ リチウムイオン電池（密閉型二次電池） DESCRIPTION OF SYMBOLS 1 Cylindrical member 2 Core metal 3 collar part 4 Sleeve 5 Large diameter part 6 Fragile part 10 Valve body 16 Electrode group 17 Battery can (a part of battery container)
20 Safety valve 22 Battery cover (part of battery container)
22A Injection port 30 Lithium ion battery (sealed secondary battery)

Claims (9)

正負極がセパレータを介して配置された電極群と、
前記電極群を浸潤する電解液と、
前記電解液を注液するための注液口が形成され、前記電極群および電解液を収容する電池容器と、
前記電池容器の注液口を密閉する安全弁と、
を備え、
前記安全弁は、前記電池容器の注液口に、一側端部が拡径された芯金と該芯金を包み込む金属製有底筒状部材とを有する弁体を予め挿入しておき、前記芯金を引き抜くことで前記筒状部材を内側から拡径して前記電池容器の注液口に装着されたものであることを特徴とする密閉型二次電池。 An electrode group in which positive and negative electrodes are disposed via a separator;
An electrolyte solution infiltrating the electrode group;
A liquid injection port for injecting the electrolytic solution is formed, and a battery container containing the electrode group and the electrolytic solution;
A safety valve for sealing the liquid injection port of the battery container;
With
In the safety valve, a valve body having a cored bar whose one end is enlarged in diameter and a metal bottomed cylindrical member that wraps the cored bar is inserted in advance into the liquid injection port of the battery container, A sealed secondary battery, wherein a diameter of the cylindrical member is expanded from the inside by pulling a metal core and is attached to a liquid injection port of the battery container. 前記筒状部材の硬度が前記芯金の硬度より小さいことを特徴とする請求項１に記載の密閉型二次電池。   The sealed secondary battery according to claim 1, wherein a hardness of the cylindrical member is smaller than a hardness of the cored bar. 前記安全弁と前記電池容器の注液口との間に熱可塑性樹脂製スリーブを介在させたことを特徴とする請求項１に記載の密閉型二次電池。   The sealed secondary battery according to claim 1, wherein a thermoplastic resin sleeve is interposed between the safety valve and a liquid injection port of the battery container. 前記安全弁は、前記電池容器の注液口に前記スリーブと前記弁体とを予め挿入しておき、前記芯金を引き抜くことで前記筒状部材を内側から拡径するとともに前記スリーブを圧縮して前記電池容器の注液口に装着されたものであることを特徴とする請求項３に記載の密閉型二次電池。   The safety valve inserts the sleeve and the valve body in advance into the injection port of the battery container, and pulls out the core bar to expand the diameter of the cylindrical member from the inside and compress the sleeve. The sealed secondary battery according to claim 3, wherein the sealed secondary battery is attached to a liquid injection port of the battery container. 前記注液口は円形状であり、前記筒状部材は円筒状であり、前記スリーブは無底円筒状であることを特徴とする請求項４に記載の密閉型二次電池。   The sealed secondary battery according to claim 4, wherein the liquid injection port is circular, the cylindrical member is cylindrical, and the sleeve is bottomless cylindrical. 前記スリーブは前記電池容器に当接する鍔部を有し、前記筒状部材は前記スリーブの鍔部に当接する鍔部を有することを特徴とする請求項４に記載の密閉型二次電池。   5. The sealed secondary battery according to claim 4, wherein the sleeve has a flange portion that comes into contact with the battery container, and the cylindrical member has a flange portion that comes into contact with the flange portion of the sleeve. 前記筒状部材を拡径した後の前記弁体の外径が、前記電池容器の注液口の内径より小さいことを特徴とする請求項４に記載の密閉型二次電池。   The sealed secondary battery according to claim 4, wherein an outer diameter of the valve body after expanding the cylindrical member is smaller than an inner diameter of a liquid injection port of the battery container. 前記スリーブの圧縮率が６０％未満であることを特徴とする請求項４に記載の密閉型二次電池。   The sealed secondary battery according to claim 4, wherein the compression ratio of the sleeve is less than 60%. 前記弁体には、前記芯金の拡径された一側端部近傍に脆弱部が形成されたことを特徴とする請求項１に記載の密閉型二次電池。   2. The sealed secondary battery according to claim 1, wherein a fragile portion is formed in the valve body in the vicinity of one end portion of the core metal whose diameter is increased.
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