JP4688605B2 - Cylindrical secondary battery - Google Patents

Cylindrical secondary battery Download PDF

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JP4688605B2
JP4688605B2 JP2005227488A JP2005227488A JP4688605B2 JP 4688605 B2 JP4688605 B2 JP 4688605B2 JP 2005227488 A JP2005227488 A JP 2005227488A JP 2005227488 A JP2005227488 A JP 2005227488A JP 4688605 B2 JP4688605 B2 JP 4688605B2
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diaphragm
battery
exhaust port
cleavage groove
upper lid
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JP2007042527A (en
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貴之 三谷
克典 鈴木
祐一 高塚
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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

本発明は円筒型二次電池に係り、特に、所定圧で開裂する開裂溝が形成され皿状で中央に平面部を有する導電性ダイヤフラムと、周縁部がダイヤフラムの周縁部に固定され中央に排気口が形成された凸部を有する上蓋キャップと、電極群を構成する正極及び負極のいずれか一方に電気的に接続されダイヤフラム側に突出した中央の平面部がダイヤフラムの電極群側の平面部に接合された接続部材とを有する上蓋を備え、上蓋がガスケットを介して円筒状電池缶にカシメ固定された大容量円筒型二次電池に関する。   The present invention relates to a cylindrical secondary battery, and more particularly, a conductive diaphragm having a dish-shaped cleavage groove that is cleaved at a predetermined pressure and having a flat portion in the center, and a peripheral portion fixed to the peripheral portion of the diaphragm and exhausted in the center. An upper lid cap having a convex portion with a mouth, and a central flat portion that is electrically connected to one of the positive electrode and the negative electrode constituting the electrode group and protrudes toward the diaphragm side is a flat portion on the electrode group side of the diaphragm. The present invention relates to a large-capacity cylindrical secondary battery including an upper lid having a joined connection member and the upper lid being caulked and fixed to a cylindrical battery can via a gasket.

従来、密閉円筒型電池は家電製品に汎用されており、最近では、密閉円筒型電池の中でも特にリチウム電池が数多く用いられるに至っている。また、リチウム電池はエネルギ密度が高いことから、電気自動車（ＥＶ）やハイブリッド車（ＨＥＶ）の車載電源としても開発が進められている。   Conventionally, sealed cylindrical batteries have been widely used in household electrical appliances, and recently, lithium batteries have been used in particular, among sealed cylindrical batteries. In addition, since lithium batteries have a high energy density, they are being developed as on-vehicle power sources for electric vehicles (EV) and hybrid vehicles (HEV).

ところが、密閉円筒型二次電池は充電装置の故障などにより過充電状態に陥ると、電解液の分解でガスが発生し電池内圧が極端に上昇することがある。特に、有機溶媒を電解液の溶媒として用いるリチウム電池においては、電池容量が大きくなるので、より確実な防爆動作が要求される。このため、薄板金属板の中央部を下方に突出させた突起部を厚板金属板に溶接し、これらの金属板の周部がカシメ固定された防爆機構を有する二次電池が開示されている（例えば、特許文献１参照）。   However, when the sealed cylindrical secondary battery is overcharged due to a failure of the charging device or the like, gas is generated due to decomposition of the electrolytic solution, and the internal pressure of the battery may extremely increase. In particular, in a lithium battery using an organic solvent as a solvent for an electrolytic solution, since the battery capacity is increased, a more reliable explosion-proof operation is required. For this reason, a secondary battery having an explosion-proof mechanism is disclosed in which a protruding portion in which a central portion of a thin metal plate is protruded downward is welded to a thick metal plate, and a peripheral portion of these metal plates is fixed by caulking. (For example, refer to Patent Document 1).

また、本発明者らは、防爆機構を内蔵した上蓋を備えた密閉円筒型リチウム二次電池を先に提案した（特許文献２参照）。図６に示すように、上蓋４０は、鉄製でニッケルメッキが施された円板状で電池の外部端子を兼ねる上蓋キャップ１を有している。上蓋キャップ１の中央には円筒状の凸部が形成されており、凸部には排気口（開口）が形成されている。上蓋キャップ１の周縁部は、アルミニウム合金製の皿状で中央に平面部を有するダイヤフラム２２の周縁部にカシメ固定されている。ダイヤフラム２２の平面部には、アルミニウム合金製で正極及び負極のいずれか一方に接続された接続板２６の中央のダイヤフラム２２側に突出した平面部が、抵抗溶接により電気的・機械的に接合されている。ダイヤフラム２２の反転圧は、電池内圧が所定圧になったときに作動（ダイヤフラム２２が上蓋キャップ１側に反転）するように抵抗溶接で設定されている。また、ダイヤフラム２２の中央部と周縁部との間には、薄肉化されており電池内圧が所定圧に達すると開裂する開裂溝３０が形成されている。開裂溝３０は、図７に示すように、円環状の開裂溝３０ａと、円環状の開裂溝３０ａから周縁部側に延びる放射状の開裂溝３０ｂとで構成されている。開裂溝３０の開裂圧は、ダイヤフラム２２の反転圧より高く設定されている。   In addition, the present inventors previously proposed a sealed cylindrical lithium secondary battery having an upper lid with a built-in explosion-proof mechanism (see Patent Document 2). As shown in FIG. 6, the upper lid 40 has an upper lid cap 1 that is made of iron and plated with nickel, and also serves as an external terminal of the battery. A cylindrical convex portion is formed in the center of the upper lid cap 1, and an exhaust port (opening) is formed in the convex portion. The peripheral portion of the upper lid cap 1 is caulked and fixed to the peripheral portion of the diaphragm 22 having a flat plate portion in the center and made of an aluminum alloy dish. The flat surface portion of the connecting plate 26 made of an aluminum alloy and connected to one of the positive electrode and the negative electrode is protruded toward the diaphragm 22 side electrically and mechanically by resistance welding to the flat surface portion of the diaphragm 22. ing. The reversing pressure of the diaphragm 22 is set by resistance welding so that it operates (the diaphragm 22 is reversed to the upper lid cap 1 side) when the battery internal pressure reaches a predetermined pressure. Further, between the central portion and the peripheral portion of the diaphragm 22, there is formed a cleaving groove 30 that is thinned and cleaves when the battery internal pressure reaches a predetermined pressure. As shown in FIG. 7, the cleavage groove 30 includes an annular cleavage groove 30 a and a radial cleavage groove 30 b extending from the annular cleavage groove 30 a toward the peripheral edge side. The cleavage pressure of the cleavage groove 30 is set higher than the reverse pressure of the diaphragm 22.

このような構造の防爆機構では、電池内圧が上昇してダイヤフラム２２の反転圧に達すると、ダイヤフラム２２が反転してダイヤフラム２２と接続板２６との接合が破断するため、接続板２６及び上蓋キャップ１間の電流が遮断される。電池内圧が更に上昇して開裂溝３０の開裂圧に達すると、開裂溝３０が開裂し電池内のガスが放出されるため、電池内圧が低減する。   In the explosion-proof mechanism having such a structure, when the internal pressure of the battery rises and reaches the reverse pressure of the diaphragm 22, the diaphragm 22 is reversed and the joint between the diaphragm 22 and the connection plate 26 is broken. The current between 1 is interrupted. When the battery internal pressure further increases and reaches the cleavage pressure of the cleavage groove 30, the cleavage groove 30 is cleaved and the gas in the battery is released, so that the battery internal pressure is reduced.

特開平８−７８６６号公報JP-A-8-7866 特開２００４−１３４２０４号公報JP 2004-134204 A

しかしながら、電池を高容量化した場合、上述した防爆機構では、過充電時の電池内圧上昇時に安全に電池を使用不能状態とすることはできるものの、電池への急激な変形を伴う外力が作用すると、図８に示すように、電池内圧の急激な上昇によりダイヤフラム２２が上蓋キャップ１に張り付く現象が起こる。このため、開裂溝３０の開裂が妨げられ内圧開放が不確実となり、電池内圧を低減することができない、という問題がある。この問題は、上述した家電製品等に用いられる容量１．３Ａｈ程度の小型電池では起こらないが、例えば、容量３．５Ａｈ以上、とりわけ、１０Ａｈを超える大容量をもつ電池で顕著となる。   However, when the capacity of the battery is increased, the above-described explosion-proof mechanism can safely make the battery unusable when the battery internal pressure rises during overcharging, but an external force with sudden deformation of the battery acts. As shown in FIG. 8, a phenomenon occurs in which the diaphragm 22 sticks to the upper lid cap 1 due to a rapid rise in the battery internal pressure. For this reason, there is a problem that the cleavage of the cleavage groove 30 is prevented, the internal pressure release becomes uncertain, and the battery internal pressure cannot be reduced. This problem does not occur in a small battery having a capacity of about 1.3 Ah used in the above-described home appliances and the like, but becomes prominent in, for example, a battery having a capacity of 3.5 Ah or more, particularly a large capacity exceeding 10 Ah.

本発明は上記事案に鑑み、大容量をもつ電池において、急激な変形を伴う外力が作用しても安全性を確保することができる円筒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 cylindrical secondary battery capable of ensuring safety even when an external force accompanied by abrupt deformation is applied to a battery having a large capacity in view of the above-mentioned cases.

上記課題を解決するために、本発明は、所定圧で開裂する開裂溝が形成され皿状で中央に平面部を有する導電性ダイヤフラムと、周縁部が前記ダイヤフラムの周縁部に固定され中央に排気口が形成された凸部を有する上蓋キャップと、電極群を構成する正極及び負極のいずれか一方に電気的に接続され前記ダイヤフラム側に突出した中央の平面部が前記ダイヤフラムの前記電極群側の平面部に接合された接続部材とを有する上蓋を備え、前記上蓋がガスケットを介して円筒状電池缶にカシメ固定された大容量円筒型二次電池において、前記開裂溝は前記ダイヤフラムの平面部に形成されており、前記排気口は、中心が前記ダイヤフラムの前記開裂溝で画定される内側部分の中心と同軸線上に位置し、大きさが前記内側部分の大きさ以上であることを特徴とする。   In order to solve the above-described problems, the present invention provides a conductive diaphragm having a dish-shaped cleavage groove that is cleaved at a predetermined pressure and having a flat portion in the center, and a peripheral portion fixed to the peripheral portion of the diaphragm and exhausted in the center. An upper lid cap having a convex portion formed with a mouth, and a central flat portion that is electrically connected to one of the positive electrode and the negative electrode constituting the electrode group and protrudes toward the diaphragm side is on the electrode group side of the diaphragm. A large-capacity cylindrical secondary battery including an upper lid having a connecting member joined to a flat surface portion, and the upper lid is caulked and fixed to a cylindrical battery can via a gasket. The cleavage groove is formed in the flat surface portion of the diaphragm. The exhaust port is located on the same axis as the center of the inner portion defined by the cleavage groove of the diaphragm, and has a size equal to or larger than the size of the inner portion. And wherein the door.

本発明の円筒型二次電池では、過充電時や電池への急激な変形を伴う外力の作用による正極及び負極の短絡時にガス発生で電池内圧が急激に上昇し、電池内圧がダイヤフラムの反転圧に達すると、ダイヤフラムが反転してダイヤフラムの平面部と接続部材の平面部との接合が破断することで、電極群を構成する正極及び負極のいずれか一方と上蓋キャップとの電気的接続が遮断され、電池内圧が更に上昇すると、ダイヤフラムの反転圧より高い圧力に設定された開裂溝の開裂圧に達する。本発明では、上蓋キャップに形成された排気口の中心がダイヤフラムの開裂溝で画定される内側部分の中心と同軸線上に位置し、排気口の大きさが開裂溝で画定される内側部分の大きさ以上のため、反転したダイヤフラムが上蓋キャップに張り付いても開裂溝が開裂して開裂溝で画定される内側部分が排気口を越えて電池外に押し出され、電池内のガスが排気口を通じて確実に排気されるので、電池内圧が低減し電池の安全性を確保することができる。   In the cylindrical secondary battery of the present invention, when the positive electrode and the negative electrode are short-circuited due to the action of an external force accompanied by rapid deformation of the battery, the battery internal pressure rapidly increases due to gas generation, and the battery internal pressure is the reverse pressure of the diaphragm. The diaphragm is inverted and the joint between the flat portion of the diaphragm and the flat portion of the connecting member is broken, so that the electrical connection between one of the positive electrode and the negative electrode constituting the electrode group and the upper lid cap is interrupted. When the battery internal pressure further rises, it reaches the cleavage pressure of the cleavage groove set to a pressure higher than the reverse pressure of the diaphragm. In the present invention, the center of the exhaust port formed in the upper lid cap is located on the same line as the center of the inner portion defined by the cleavage groove of the diaphragm, and the size of the inner portion is defined by the cleavage groove. For this reason, even if the inverted diaphragm sticks to the top cap, the cleavage groove is broken and the inner part defined by the cleavage groove is pushed out of the battery beyond the exhaust port, and the gas in the battery passes through the exhaust port. Since the exhaust is reliably performed, the internal pressure of the battery is reduced and the safety of the battery can be ensured.

この場合において、上蓋キャップの凸部に円筒型二次電池同士を接続するためのブスバを接合し、ブスバに中心が排気口の中心と同軸線上に位置する貫通穴を形成し、該貫通穴の大きさを排気口の大きさ以上としてもよい。このようにすれば、円筒型二次電池同士を接続して使用するときに、電池への急激な変形を伴う外力が作用しても開裂溝の開裂により電池内のガスが上蓋キャップの排気口及びブスバの貫通穴を通じて確実に排気されるので、安全性を確保することができる。このとき、排気口及び貫通穴が略円形で、開裂溝が円環状であり、排気口の最小径をＡ、開裂溝の円環外径をＢ、貫通穴の最小径をＣとしたときに、最小径Ｃ≧最小径Ａ≧円環外径Ｂとしてもよい。また、ダイヤフラムに、円環状の開裂溝から周縁部側に放射状の開裂溝が更に形成されていてもよい。更に、開裂溝がダイヤフラムの上蓋キャップ側の平面部に形成されていることが好ましい。   In this case, a bus bar for connecting the cylindrical secondary batteries to each other is joined to the convex portion of the upper lid cap, and a through hole whose center is located on the same line as the center of the exhaust port is formed in the bus bar. The size may be greater than the size of the exhaust port. In this way, when the cylindrical secondary batteries are connected and used, even if an external force accompanied by rapid deformation of the batteries is applied, the gas in the batteries is discharged from the opening of the top cap by the cleavage of the cleavage groove. And since it exhausts reliably through the through-hole of a bus bar, safety | security can be ensured. At this time, when the exhaust port and the through hole are substantially circular, the cleavage groove is annular, the minimum diameter of the exhaust port is A, the outer diameter of the ring of the cleavage groove is B, and the minimum diameter of the through hole is C The minimum diameter C ≧ minimum diameter A ≧ annular outer diameter B may be set. Further, a radial cleavage groove may be further formed on the diaphragm from the annular cleavage groove to the peripheral edge side. Furthermore, it is preferable that the cleavage groove is formed in the flat portion on the upper lid cap side of the diaphragm.

本発明によれば、上蓋キャップに形成された排気口の中心がダイヤフラムの開裂溝で画定される内側部分の中心と同軸線上に位置し、排気口の大きさが開裂溝で画定される内側部分の大きさ以上のため、反転したダイヤフラムが上蓋キャップに張り付いても開裂溝が開裂して内側部分が排気口を越えて電池外に押し出されるので、電池内圧が低減し電池の安全性を確保することができる、という効果を得ることができる。   According to the present invention, the center of the exhaust port formed in the upper lid cap is located on the same axis as the center of the inner portion defined by the cleavage groove of the diaphragm, and the inner portion of which the size of the exhaust port is defined by the cleavage groove. Therefore, even if the inverted diaphragm sticks to the top lid cap, the cleavage groove is broken and the inner part is pushed out of the battery beyond the exhaust port, reducing the internal pressure of the battery and ensuring the safety of the battery. It is possible to obtain the effect of being able to.

以下、図面を参照して、本発明を円筒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。   Embodiments in which the present invention is applied to a cylindrical lithium ion battery will be described below with reference to the drawings.

（構成）
図１に示すように、本実施形態の円筒型リチウムイオン電池５０は、中空円筒状の軸芯の周りに、正極及び負極を、リチウムイオンの通過を許容するポリエチレン製微多孔膜からなるセパレータを介して捲回した電極捲回群１１を備えている。 (Constitution)
As shown in FIG. 1, a cylindrical lithium ion battery 50 according to this embodiment includes a positive electrode and a negative electrode around a hollow cylindrical shaft core, and a separator made of a polyethylene microporous membrane that allows lithium ions to pass therethrough. And an electrode winding group 11 wound around.

正極は、正極活物質のリチウムマンガン複合酸化物の粉末９０重量部に対して、導電材として炭素粉末５重量部と、結着剤としてポリフッ化ビニリデン（以下、ＰＶＤＦと略記する。）５重量部と、を添加し、これに分散溶媒としてＮ−メチルピロリドン（以下、ＮＭＰと略記する。）を添加、混練したスラリを、厚さ２０μｍのアルミニウム箔（正極集電体）の両面に均一に塗布し、乾燥させた後、プレス、集電するための一部を残して短冊状に裁断して得られたものである。集電するために残した部分には正極タブが形成されている。上述したリチウムマンガン複合酸化物には、例えば、マンガン酸リチウム（ＬｉＭｎ２Ｏ４）又はＬｉＭｎ２Ｏ４のリチウムサイト又はマンガンサイトを他の金属元素で置換又はドープした、例えば、化学式Ｌｉ１＋ｘＭｙＭｎ２−ｘ−ｙＯ４（ＭはＬｉ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ａｌ、Ｃｒ、Ｍｇ、Ｚｎ、Ｖ、Ｇａ、Ｂ、Ｆ）や層状系マンガン酸リチウム（ＬｉＭｎｘＭ１−ｘＯ２）（ＭはＬｉ、Ｃｏ、Ｎｉ、Ｆｅ、Ｃｕ、Ａｌ、Ｃｒ、Ｍｇ、Ｚｎ、Ｖ、Ｇａ、Ｂ、Ｆの１種類以上の金属元素）を用いることができる。 In the positive electrode, 5 parts by weight of carbon powder as a conductive material and 5 parts by weight of polyvinylidene fluoride (hereinafter abbreviated as PVDF) as a binder with respect to 90 parts by weight of lithium manganese composite oxide powder as a positive electrode active material. Then, N-methylpyrrolidone (hereinafter abbreviated as NMP) is added as a dispersion solvent, and the kneaded slurry is uniformly applied to both sides of a 20 μm thick aluminum foil (positive electrode current collector). Then, after drying, it was obtained by cutting into a strip shape, leaving a part for pressing and collecting current. A positive electrode tab is formed in a portion left for current collection. In the lithium manganese composite oxide described above, for example, lithium manganate (LiMn 2 O 4 ) or lithium sites or manganese sites of LiMn 2 O 4 are substituted or doped with other metal elements, for example, chemical formula Li 1 + x M y Mn 2−x−y O 4 (M is Li, Co, Ni, Fe, Cu, Al, Cr, Mg, Zn, V, Ga, B, F) or layered lithium manganate (LiMn x M 1-x O 2 ) (M is one or more metal elements of Li, Co, Ni, Fe, Cu, Al, Cr, Mg, Zn, V, Ga, B, and F).

一方、負極は、負極活物質の非晶質炭素粉末９０重量部に、結着剤としてＰＶＤＦの１０重量部を添加し、これに分散溶媒としてＮＭＰを添加、混練したスラリを、厚さ１０μｍの圧延銅箔（負極集電体）の両面に塗布し、乾燥させた後、所定寸法にプレス、集電するための一部を残して短冊状に裁断して得られたものである。集電するために残した部分には負極タブが形成されている。負極活物質には、上述した非晶質炭素の他に、リチウムを吸蔵放出可能な物質または金属リチウムを用いるようにしてもよい。   On the other hand, the negative electrode was prepared by adding 10 parts by weight of PVDF as a binder to 90 parts by weight of amorphous carbon powder of the negative electrode active material, adding NMP as a dispersion solvent thereto, and kneading the slurry with a thickness of 10 μm. It was obtained by applying it to both sides of a rolled copper foil (negative electrode current collector), drying it, and cutting it into strips, leaving a part for pressing and collecting current to a predetermined size. A negative electrode tab is formed in a portion left for current collection. As the negative electrode active material, in addition to the amorphous carbon described above, a material capable of occluding and releasing lithium or metallic lithium may be used.

電極捲回群１１は有底円筒状の金属製電池缶１０内に挿入されており、上述した正極タブ及び負極タブは電極捲回群１１の互いに反対側の両端面に位置するように配置されている。軸芯の下端には、集電用の負極集電リングが固定されており、負極集電リングの周縁部には負極タブが超音波溶接されている。負極集電リングは、電池缶１０に抵抗溶接されている。一方、軸芯の上端には集電用の正極集電リング１４が固定されており、正極集電リング１４の周縁部には正極タブが超音波溶接されている。正極集電リング１４には、短冊状のアルミニウム箔を積層し略Ｕ字状に折り曲げられた正極リード板３２の一側が溶接されている。正極リード板３２の他側は、電極捲回群１１の上部に配置された上蓋２０を構成するアルミニウム合金製のスプリッタ４の底面に溶接されている。   The electrode winding group 11 is inserted into a bottomed cylindrical metal battery can 10, and the above-described positive electrode tab and negative electrode tab are disposed so as to be positioned on both end surfaces of the electrode winding group 11 opposite to each other. ing. A negative electrode current collecting ring for current collection is fixed to the lower end of the shaft core, and a negative electrode tab is ultrasonically welded to the peripheral edge of the negative electrode current collecting ring. The negative electrode current collector ring is resistance-welded to the battery can 10. On the other hand, a positive electrode current collecting ring 14 for current collection is fixed to the upper end of the shaft core, and a positive electrode tab is ultrasonically welded to the peripheral portion of the positive electrode current collecting ring 14. The positive electrode current collector ring 14 is welded to one side of a positive electrode lead plate 32 that is formed by laminating strip-shaped aluminum foil and bent into a substantially U shape. The other side of the positive electrode lead plate 32 is welded to the bottom surface of the aluminum alloy splitter 4 constituting the upper lid 20 disposed on the upper part of the electrode winding group 11.

図２に示すように、上蓋２０は、鉄製でニッケルメッキが施された円板状の上蓋キャップ（トップキャップ）１を有している。円板の中央には上方に向けて突出した円筒状の突起（凸部）が形成されており、突起の上面には電池内部で発生したガスを排出するための排気口（開口）９が形成されている。排気口９は略円形の形状に形成されている。上蓋キャップ１は正極外部出力端子としての機能を有しており、上蓋キャップ１の周部はダイヤフラム２の周部でカシメ固定されている。ダイヤフラム２は、アルミニウム合金製で下方に底部が形成された皿状の形状を有している。皿状の底部は平面状でありダイヤフラム２の中央部を形成している。ダイヤフラム２の上蓋キャップ１側の中央部には、薄肉化されており電池内圧が所定圧に達すると開裂する開裂溝８が形成されている。   As shown in FIG. 2, the upper lid 20 has a disk-shaped upper lid cap (top cap) 1 made of iron and plated with nickel. A cylindrical projection (convex portion) that protrudes upward is formed at the center of the disk, and an exhaust port (opening) 9 for discharging gas generated inside the battery is formed on the upper surface of the projection. Has been. The exhaust port 9 is formed in a substantially circular shape. The upper lid cap 1 has a function as a positive electrode external output terminal, and the peripheral portion of the upper lid cap 1 is fixed by caulking with the peripheral portion of the diaphragm 2. The diaphragm 2 is made of an aluminum alloy and has a dish-like shape with a bottom portion formed below. The dish-shaped bottom is flat and forms the center of the diaphragm 2. In the central portion of the diaphragm 2 on the side of the upper cap 1, a tear groove 8 is formed that is thinned and cleaves when the battery internal pressure reaches a predetermined pressure.

図３（Ｂ）に示すように、開裂溝８は、円環状の開裂溝８ａと、開裂溝８ａからダイヤフラム２の周縁部側に延びる放射状の開裂溝８ｂとで形成されている。開裂溝８ａは円環の外径ｂ（以下、円環径ｂという。）（円環外径Ｂ）に設定されている。図３（Ａ）に示すように、上蓋キャップ１に形成された排気口９は最小径ａ（以下、排気口径ａという。）（最小径Ａ）に設定されている。排気口９は、中心が開裂溝８ａの円環（ダイヤフラム２の開裂溝８ａで画定される内側部分）の中心と同軸線上（同心位置）に位置している。排気口９の大きさは、開裂溝８ａの円環の大きさ以上に形成されており、排気口径ａは円環径ｂ以上（排気口径ａ≧円環径ｂ）に設定されている。   As shown in FIG. 3B, the cleavage groove 8 is formed by an annular cleavage groove 8a and a radial cleavage groove 8b extending from the cleavage groove 8a toward the peripheral edge side of the diaphragm 2. The cleavage groove 8a is set to an outer diameter b (hereinafter referred to as an annulus diameter b) (an annulus outer diameter B). As shown in FIG. 3A, the exhaust port 9 formed in the upper lid cap 1 is set to a minimum diameter a (hereinafter referred to as an exhaust port diameter a) (minimum diameter A). The exhaust port 9 is positioned coaxially (concentrically) with the center of the ring of the cleavage groove 8a (inner portion defined by the cleavage groove 8a of the diaphragm 2). The size of the exhaust port 9 is formed to be larger than the size of the ring of the cleavage groove 8a, and the exhaust port diameter a is set to be equal to or larger than the ring diameter b (exhaust port diameter a ≧ annular diameter b).

図２に示すように、ダイヤフラム２の中央部の底面（電極捲回群１１側の面）には、アルミニウム合金製でダイヤフラム２より肉厚が薄い接続板（接続部材）６が配置されている。接続板６は、中央部の上面が平面状で上方（ダイヤフラム２側）に突出しており、抵抗溶接により接合部７でダイヤフラム２に電気的・機械的に接合されている。ダイヤフラム２と接続板６との接合強度は、リチウムイオン電池５０の内圧が所定圧になったときにダイヤフラム２が作動（ダイヤフラム２が上蓋キャップ１側に反転）するように、抵抗溶接で調整されている。   As shown in FIG. 2, a connection plate (connecting member) 6 made of an aluminum alloy and having a thickness smaller than that of the diaphragm 2 is disposed on the bottom surface (surface on the electrode winding group 11 side) of the diaphragm 2. . The connection plate 6 has a flat upper surface at the center and protrudes upward (diaphragm 2 side), and is electrically and mechanically joined to the diaphragm 2 at the joint 7 by resistance welding. The bonding strength between the diaphragm 2 and the connection plate 6 is adjusted by resistance welding so that the diaphragm 2 operates (the diaphragm 2 is reversed to the upper lid cap 1 side) when the internal pressure of the lithium ion battery 50 reaches a predetermined pressure. ing.

ダイヤフラム２の中央部の底面と接続板６の周縁部との間には、フランジ部がダイヤフラム２の中央部の底面に当接するポリプロピレン樹脂製で円環状のブッシュ５を介して、扁平ドーナツ状（皿状の中央部が空けられた形状）のスプリッタ４が狭持されている。このため、スプリッタ４と接続板６とは電気的に接続されている。また、スプリッタ４には、電池内部とダイヤフラム２とを連通させる複数の貫通穴が形成されている。ダイヤフラム２のスプリッタ４が沿う部分と、スプリッタ４とが、図１に示した正極集電リング１４内に収容されている。スプリッタ４の外周部は、断面略Ｔ字状の樹脂製絶縁リング３によりダイヤフラム２の底面と所定間隔を隔てて係止されている。絶縁リング３は、内面側にスプリッタ４の外周部を支持する複数のツメを有しており、絶縁リング３とツメとは一体成形されている。なお、ダイヤフラム２、スプリッタ４、上蓋キャップ１及び接続板６は、プレス加工により成形されている。   Between the bottom surface of the center portion of the diaphragm 2 and the peripheral edge portion of the connection plate 6, a flat donut shape (with a flange portion made of polypropylene resin abutting against the bottom surface of the center portion of the diaphragm 2 is interposed ( A splitter 4 having a plate-like central portion is sandwiched. For this reason, the splitter 4 and the connection plate 6 are electrically connected. The splitter 4 is formed with a plurality of through holes that allow the inside of the battery to communicate with the diaphragm 2. The portion along the splitter 4 of the diaphragm 2 and the splitter 4 are accommodated in the positive electrode current collecting ring 14 shown in FIG. The outer periphery of the splitter 4 is locked with a predetermined interval from the bottom surface of the diaphragm 2 by a resin insulating ring 3 having a substantially T-shaped cross section. The insulating ring 3 has a plurality of claws that support the outer peripheral portion of the splitter 4 on the inner surface side, and the insulating ring 3 and the claws are integrally formed. The diaphragm 2, the splitter 4, the upper lid cap 1, and the connection plate 6 are formed by pressing.

図１に示すように、電池缶１０内に非水電解液が所定量注入された後、上蓋２０の周縁部は電池缶１０にガスケット１３を介してカシメ固定されて電池内が密閉されている。非水電解液には、６フッ化リン酸リチウムや４フッ化ホウ酸リチウムをエチレンカーボネート、ジメチルカーボネートなどの有機溶媒に１モル／リットル程度溶解した電解液が用いられている。本実施形態のリチウムイオン電池５０は１０Ａｈを超える容量を有している。なお、非水電解液には、これ以外に、例えば、カーボネート系、スルホラン系、エーテル系、ラクトン系等の有機溶剤を単体または混合して用いた溶媒中にリチウム塩を溶解させたものを用いることができる。   As shown in FIG. 1, after a predetermined amount of nonaqueous electrolyte is injected into the battery can 10, the peripheral edge of the upper lid 20 is caulked and fixed to the battery can 10 via a gasket 13 to seal the inside of the battery. . As the nonaqueous electrolytic solution, an electrolytic solution obtained by dissolving lithium hexafluorophosphate or lithium tetrafluoroborate in an organic solvent such as ethylene carbonate or dimethyl carbonate in an amount of about 1 mol / liter is used. The lithium ion battery 50 of the present embodiment has a capacity exceeding 10 Ah. As the non-aqueous electrolyte, for example, a solution obtained by dissolving a lithium salt in a solvent in which an organic solvent such as carbonate, sulfolane, ether, or lactone is used alone or in combination is used. be able to.

（作用等）
次に、本実施形態のリチウムイオン電池５０の電池異常時の作用等について説明する。 (Action etc.)
Next, the operation of the lithium ion battery 50 according to this embodiment when the battery is abnormal will be described.

本実施形態のリチウムイオン電池５０では、接合部７の接合が解除されダイヤフラム２が上蓋キャップ１側に反転する反転圧と、ダイヤフラム２に形成された開裂溝８が開裂する開裂圧とが設定されており、反転圧は大気圧より大きく（例えば、１．５ＭＰａ）、開裂圧は反転圧より大きい値に設定されている（例えば、２ＭＰａ）。   In the lithium ion battery 50 of the present embodiment, the reversal pressure at which the joint 7 is released and the diaphragm 2 is reversed to the upper lid cap 1 side, and the cleavage pressure at which the cleavage groove 8 formed in the diaphragm 2 is cleaved are set. The reverse pressure is larger than atmospheric pressure (for example, 1.5 MPa), and the cleavage pressure is set to a value larger than the reverse pressure (for example, 2 MPa).

電池内圧が反転圧に達すると、接続板６が破断し（ダイヤフラム２の中央部の底面と、接続板６の中央部の上面との接合部７の接合が解除され）て、ダイヤフラム２が上蓋キャップ１側に反転する。これにより、電極捲回群１１の正極タブ、正極集電リング１４、正極リード板３２、スプリッタ４、接続板６、ダイヤフラム２、上蓋キャップ１（正極外部出力端子）の順で接続された電流経路のうち、接続板６とダイヤフラム２との間の電流経路が遮断されるので、上蓋キャップ１及び電極捲回群１１間の通電が遮断される。電池内圧が更に上昇して開裂圧に達すると、開裂溝８が開裂する。これにより、電池内のガスが排気口９を通じて電池外に排気されるため、電池内圧が低減する。このため、リチウムイオン電池５０が過充電状態に陥っても、安全にリチウムイオン電池５０を使用不能状態とすることができる。なお、反転圧は大気圧より大きい値に設定されているので、一旦ダイヤフラム２が反転すると、再度、ダイヤフラム２の中央部の底面と、接続板６の中央部の上面とが接触することはない。   When the internal pressure of the battery reaches the reverse pressure, the connection plate 6 is broken (the connection between the bottom surface of the central portion of the diaphragm 2 and the upper surface of the central portion of the connection plate 6 is released), and the diaphragm 2 is covered with the upper lid. Invert to cap 1 side. As a result, the current path in which the positive electrode tab of the electrode winding group 11, the positive electrode current collecting ring 14, the positive electrode lead plate 32, the splitter 4, the connection plate 6, the diaphragm 2, and the upper lid cap 1 (positive electrode external output terminal) are connected in this order. Among them, since the current path between the connection plate 6 and the diaphragm 2 is interrupted, the energization between the upper lid cap 1 and the electrode winding group 11 is interrupted. When the battery internal pressure further increases and reaches the cleavage pressure, the cleavage groove 8 is cleaved. Thereby, since the gas in the battery is exhausted outside the battery through the exhaust port 9, the internal pressure of the battery is reduced. For this reason, even if the lithium ion battery 50 falls into an overcharged state, the lithium ion battery 50 can be safely made unusable. Since the reversal pressure is set to a value larger than the atmospheric pressure, once the diaphragm 2 is reversed, the bottom surface of the central portion of the diaphragm 2 and the top surface of the central portion of the connection plate 6 do not come into contact again. .

また、リチウムイオン電池５０への急激な変形を伴う外力が作用した場合（例えば、リチウムイオン電池５０が圧壊されたり、釘等の異物で突き刺された場合）には、電極捲回群１１の正極及び負極が短絡し、非水電解液が加速度的に分解しガスが発生する。とりわけ、本実施形態のリチウムイオン電池５０は容量１０Ａｈを超えており、非水電解液の量も多いため、電池内圧は熱暴走を伴って急激に上昇する。このため、電池内圧が反転圧に達すると、ダイヤフラム２が上蓋キャップ１側に反転して上蓋キャップ１の内側に張り付いてしまう。リチウムイオン電池５０では、開裂溝８の円環径ｂが上蓋キャップ１に形成された排気口９の排気口径ａ以下（排気口径ａ≧円環径ｂ）のため、図４に示すように、開裂溝８が開裂して開裂溝８ａの内側部分が排気口９から上蓋キャップ１を越えて電池外に押し上げられるので、電池缶１０内のガスが排気口９を通じて電池外に放出される。従って、リチウムイオン電池５０は、急激な変形を伴う外力が作用した場合でも、電池内圧を確実に低減させることができるので、電池の安全性を確保することができる。   Further, when an external force accompanied by abrupt deformation is applied to the lithium ion battery 50 (for example, when the lithium ion battery 50 is crushed or pierced with a foreign object such as a nail), the positive electrode of the electrode winding group 11 And the negative electrode is short-circuited, and the non-aqueous electrolyte is decomposed at an accelerated rate to generate gas. In particular, since the lithium ion battery 50 of the present embodiment has a capacity exceeding 10 Ah and the amount of non-aqueous electrolyte is large, the internal pressure of the battery rapidly increases with thermal runaway. For this reason, when the battery internal pressure reaches the reverse pressure, the diaphragm 2 is reversed to the upper lid cap 1 side and sticks to the inner side of the upper lid cap 1. In the lithium ion battery 50, since the annular diameter b of the cleavage groove 8 is equal to or smaller than the exhaust diameter a of the exhaust opening 9 formed in the upper cap 1 (exhaust diameter a ≧ annular diameter b), as shown in FIG. Since the cleavage groove 8 is cleaved and the inner part of the cleavage groove 8 a is pushed up from the exhaust port 9 over the upper cap 1 to the outside of the battery, the gas in the battery can 10 is released to the outside of the battery through the exhaust port 9. Therefore, the lithium ion battery 50 can reliably reduce the battery internal pressure even when an external force with abrupt deformation is applied, so that the safety of the battery can be ensured.

更に、本実施形態のリチウムイオン電池５０では、開裂溝８ａ、８ｂがダイヤフラム２の上蓋キャップ１側の中央部に形成されている。このため、ダイヤフラム２の電極捲回群１１側の中央部に接続板６を抵抗溶接で接合するときに、開裂溝８ａ、８ｂの損傷を防止することができる。   Furthermore, in the lithium ion battery 50 of the present embodiment, the cleavage grooves 8 a and 8 b are formed in the center portion on the upper lid cap 1 side of the diaphragm 2. For this reason, when connecting plate 6 is joined to the central part of diaphragm 2 on the side of electrode winding group 11 by resistance welding, damage to cleavage grooves 8a and 8b can be prevented.

なお、本実施形態では、排気口９を略円形、開裂溝８ａを円環状とする例を示したが、本発明はこれに限定されるものではない。例えば、四角形状や多角形状としてもよく、排気口９の大きさが開裂溝８ａの内側部分の大きさ以上であればよい。   In the present embodiment, the exhaust port 9 has a substantially circular shape, and the cleavage groove 8a has an annular shape. However, the present invention is not limited to this. For example, it may be a quadrangular shape or a polygonal shape, as long as the size of the exhaust port 9 is equal to or larger than the size of the inner portion of the cleavage groove 8a.

また、本実施形態では、リチウムイオン電池について例示したが、本発明はこれに限定されるものではなく、例えば、１０Ａｈを超える容量をもつ円筒型の二次電池に適用可能である。また、電極捲回群１１を構成する正極、負極、セパレータや非水電解液について例示したが、本発明はこれらの活物質、材質、電解質、溶媒等に制限されるものでないことは論を待たない。更に、本実施形態では、電極捲回群１１の正極を上蓋キャップ１に接続して正極外部出力端子とした例を示したが、負極を上蓋キャップ１に接続するようにしてもよい。   In the present embodiment, the lithium ion battery is exemplified, but the present invention is not limited to this, and can be applied to, for example, a cylindrical secondary battery having a capacity exceeding 10 Ah. Moreover, although the positive electrode, the negative electrode, the separator, and the nonaqueous electrolytic solution constituting the electrode winding group 11 have been exemplified, it is awaited that the present invention is not limited to these active materials, materials, electrolytes, solvents, and the like. Absent. Further, in the present embodiment, the example in which the positive electrode of the electrode winding group 11 is connected to the upper lid cap 1 to form the positive electrode external output terminal is shown, but the negative electrode may be connected to the upper lid cap 1.

次に、本実施形態に従って作製した円筒型リチウムイオン電池５０の実施例について説明する。なお、比較のために作製した比較例の円筒型リチウムイオン電池についても併記する。また、実施例及び比較例の電池において、開裂圧はすべて２．０ＭＰａとし、電池の容量はすべて１３Ａｈとした。   Next, examples of the cylindrical lithium ion battery 50 manufactured according to the present embodiment will be described. In addition, it describes together about the cylindrical lithium ion battery of the comparative example produced for the comparison. In the batteries of Examples and Comparative Examples, the cleavage pressures were all 2.0 MPa, and the battery capacities were all 13 Ah.

以下の実施例及び比較例では、上蓋キャップ１に形成された排気口９の排気口径ａ、ダイヤフラム２に形成された開裂溝８ａの円環径ｂをそれぞれ変えて上蓋２０を作製し、リチウムイオン電池５０を作製した。作製したリチウムイオン電池５０を２セル使用し、電池接続用のブスバを２個用いて２並列に抵抗溶接で接続し２パラセルユニットとした。図５（Ａ）、（Ｂ）に示すように、ブスバ６０は扁平楕円状の金属板で構成されており、金属板の長手方向の一側には電池内で発生したガスの放出経路となる略円形の貫通穴６２が形成されている。ブスバ６０は、リチウムイオン電池５０の上蓋キャップ１の上面に抵抗溶接で固定されている。貫通穴６２の中心は排気口９の中心と同軸線上（同心位置）に位置している。貫通穴６２の大きさは、排気口９の大きさ以上に形成されている。すなわち、貫通穴６２の最小径ｃ（以下、貫通穴最小径ｃという。）（最小径Ｃ）は、図５（Ｂ）、（Ｃ）に示すように、排気口径ａ以上（貫通穴最小径ｃ≧排気口径ａ）に設定されている。貫通穴６２の形状は、上述した略円形の他に、例えば、四角形状や多角形状としてもよく、貫通穴６２の大きさが排気口９の大きさ以上であればよい。２セルのリチウムイオン電池５０にそれぞれ固定されたブスバ６０の他側同士を抵抗溶接で接合することで、２パラセルユニットを作製することができる。   In the following examples and comparative examples, the upper lid 20 is manufactured by changing the exhaust port diameter a of the exhaust port 9 formed in the upper cap cap 1 and the annular diameter b of the cleavage groove 8a formed in the diaphragm 2, respectively. A battery 50 was produced. Two lithium ion batteries 50 were used, and two bus bars for battery connection were used, and two parallel connection was made by resistance welding in two parallel units. As shown in FIGS. 5A and 5B, the bus bar 60 is formed of a flat elliptical metal plate, and a discharge path for gas generated in the battery is provided on one side in the longitudinal direction of the metal plate. A substantially circular through hole 62 is formed. The bus bar 60 is fixed to the upper surface of the upper lid cap 1 of the lithium ion battery 50 by resistance welding. The center of the through hole 62 is located coaxially with the center of the exhaust port 9 (concentric position). The size of the through hole 62 is larger than the size of the exhaust port 9. That is, the minimum diameter c of the through hole 62 (hereinafter referred to as the through hole minimum diameter c) (minimum diameter C) is equal to or greater than the exhaust port diameter a (as shown in FIGS. 5B and 5C). c ≧ exhaust port diameter a). The shape of the through hole 62 may be, for example, a square shape or a polygonal shape in addition to the substantially circular shape described above, and the size of the through hole 62 only needs to be greater than or equal to the size of the exhaust port 9. A two-paracell unit can be produced by joining the other sides of the bus bars 60 fixed to the two-cell lithium-ion battery 50 by resistance welding.

（実施例１）
下表１に示すように、実施例１では、排気口径ａを６ｍｍ、円環径ｂを６ｍｍに設定したリチウムイオン電池５０を作製し、貫通穴最小径ｃを６ｍｍに設定したブスバ６０で２パラセルユニットを作製した。排気口径ａ、円環径ｂ、貫通穴最小径ｃの大きさを比較すると、ｃ＝ａ＝ｂとなる。 Example 1
As shown in Table 1 below, in Example 1, a lithium ion battery 50 having an exhaust port diameter a set to 6 mm and an annular diameter b set to 6 mm was manufactured. A paracel unit was prepared. Comparing the sizes of the exhaust port diameter a, the annular diameter b, and the through-hole minimum diameter c, c = a = b.

Figure 0004688605
Figure 0004688605

（実施例２）
表１に示すように、実施例２では、排気口径ａを１２ｍｍ、円環径ｂを１２ｍｍに設定したリチウムイオン電池５０を作製し、貫通穴最小径ｃを１２ｍｍに設定したブスバ６０で２パラセルユニットを作製した。排気口径ａ、円環径ｂ、貫通穴最小径ｃの大きさを比較すると、ｃ＝ａ＝ｂとなる。 (Example 2)
As shown in Table 1, in Example 2, a lithium ion battery 50 with an exhaust port diameter a set to 12 mm and an annular diameter b set to 12 mm was manufactured, and 2 paracels were formed using a bus bar 60 with a through-hole minimum diameter c set to 12 mm. A unit was made. Comparing the sizes of the exhaust port diameter a, the annular diameter b, and the through-hole minimum diameter c, c = a = b.

（実施例３）
表１に示すように、実施例３では、排気口径ａを６ｍｍ、円環径ｂを５ｍｍに設定したリチウムイオン電池５０を作製し、貫通穴最小径ｃを７ｍｍに設定したブスバ６０で２パラセルユニットを作製した。排気口径ａ、円環径ｂ、貫通穴最小径ｃの大きさを比較すると、ｃ＞ａ＞ｂとなる。 (Example 3)
As shown in Table 1, in Example 3, a lithium ion battery 50 having an exhaust port diameter a set to 6 mm and an annular diameter b set to 5 mm was manufactured, and 2 paracels were formed using a bus bar 60 having a minimum through hole diameter c set to 7 mm. A unit was made. When the sizes of the exhaust port diameter a, the annular diameter b, and the through-hole minimum diameter c are compared, c>a> b.

（実施例４）
表１に示すように、実施例４では、排気口径ａを６ｍｍ、円環径ｂを５ｍｍに設定したリチウムイオン電池５０を作製し、貫通穴最小径ｃを６ｍｍに設定したブスバ６０で２パラセルユニットを作製した。排気口径ａ、円環径ｂ、貫通穴最小径ｃの大きさを比較すると、ｃ＝ａ＞ｂとなる。 Example 4
As shown in Table 1, in Example 4, a lithium ion battery 50 having an exhaust port diameter a set to 6 mm and an annular diameter b set to 5 mm was manufactured, and two paracels were formed using a bus bar 60 having a minimum through-hole diameter c set to 6 mm. A unit was made. Comparing the sizes of the exhaust port diameter a, the annular diameter b, and the through-hole minimum diameter c, c = a> b.

（比較例１）
表１に示すように、比較例１では、排気口径ａを６ｍｍ、円環径ｂを１２ｍｍに設定したリチウムイオン電池を作製し、貫通穴最小径ｃを７ｍｍに設定したブスバ６０で２パラセルユニットを作製した。排気口径ａ、円環径ｂ、貫通穴最小径ｃの大きさを比較すると、ａ＜ｃ＜ｂとなる。 (Comparative Example 1)
As shown in Table 1, in Comparative Example 1, a lithium ion battery having an exhaust port diameter a of 6 mm and an annular diameter b of 12 mm was prepared, and a 2-paracell unit was formed by a bus bar 60 having a through-hole minimum diameter c of 7 mm. Was made. When the sizes of the exhaust port diameter a, the annular diameter b, and the through-hole minimum diameter c are compared, a <c <b.

（比較例２）
表１に示すように、比較例２では、排気口径ａを６ｍｍ、円環径ｂを１２ｍｍに設定したリチウムイオン電池を作製し、貫通穴最小径ｃを１３ｍｍに設定したブスバ６０で２パラセルユニットを作製した。排気口径ａ、円環径ｂ、貫通穴最小径ｃの大きさを比較すると、ａ＜ｂ＜ｃとなる。 (Comparative Example 2)
As shown in Table 1, in Comparative Example 2, a lithium ion battery having an exhaust port diameter a set to 6 mm and an annular diameter b set to 12 mm was prepared, and a 2-paracell unit was formed using a bus bar 60 having a minimum through-hole diameter c set to 13 mm. Was made. When the sizes of the exhaust port diameter a, the annular diameter b, and the through-hole minimum diameter c are compared, a <b <c.

（比較例３）
表１に示すように、比較例３では、排気口径ａを７ｍｍ、円環径ｂを１０ｍｍに設定したリチウムイオン電池を作製し、貫通穴最小径ｃを１０ｍｍに設定したブスバ６０で２パラセルユニットを作製した。排気口径ａ、円環径ｂ、貫通穴最小径ｃの大きさを比較すると、ａ＜ｂ＝ｃとなる。 (Comparative Example 3)
As shown in Table 1, in Comparative Example 3, a lithium ion battery having an exhaust port diameter a set to 7 mm and an annular diameter b set to 10 mm was prepared, and a 2-paracell unit was formed using a bus bar 60 having a through-hole minimum diameter c set to 10 mm. Was made. Comparing the sizes of the exhaust port diameter a, the annular diameter b, and the through-hole minimum diameter c, a <b = c.

（試験、評価）
各実施例及び比較例の２パラセルユニットについて、過充電試験、釘刺し試験、圧壊試験を行い電池挙動を評価した。過充電試験では、２パラセルユニットに対して２６Ａ（１セルあたり１Ｃ）の直流電流で過充電となるまで充電した。釘刺し試験では、電池をＳＯＣ（充電状態）１００％に調整した後、半径５．５ｍｍの釘を１．６ｍ／ｍｉｎの速度で電極捲回群１１の捲回軸に対して垂直方向から電池長手方向の中心へ長手方向に対して垂直な方向で降ろし、電池に釘を刺した。圧壊試験では、電池をＳＯＣ１００％に調整した後、半径１７．５ｍｍの圧壊治具を１．６ｍ／ｍｉｎの速度で電極捲回群１１の捲回軸に対して垂直方向から電池長手方向の中心へ長手方向に対して垂直な方向で降ろし、電池に外圧をかけた。各試験における電池挙動は、◎；試験電池の１００％について破裂発火が認められない、○；試験電池の８１〜９９％について破裂発火が認められない、△；試験電池の６１〜８０％について破裂発火が認められない、×；試験電池の０〜６０％について破裂発火が認められない、の４段階でそれぞれ評価した。各試験の評価結果を下表２に示す。なお、各試験は試験回数ｎ＝２０で行った。 (Examination, evaluation)
About 2 paracell units of each Example and the comparative example, the overcharge test, the nail penetration test, and the crush test were done, and the battery behavior was evaluated. In the overcharge test, the 2 paracell unit was charged with a direct current of 26 A (1 C per cell) until it was overcharged. In the nail penetration test, after adjusting the battery to SOC (charged state) 100%, a nail with a radius of 5.5 mm was charged at a speed of 1.6 m / min from the direction perpendicular to the winding axis of the electrode winding group 11. The battery was lowered to the longitudinal center in a direction perpendicular to the longitudinal direction, and a nail was inserted into the battery. In the crushing test, after adjusting the battery to 100% SOC, a crushing jig having a radius of 17.5 mm is centered in the battery longitudinal direction from the direction perpendicular to the winding axis of the electrode winding group 11 at a speed of 1.6 m / min. The battery was lowered in a direction perpendicular to the longitudinal direction, and external pressure was applied to the battery. Battery behavior in each test is as follows: ◎: No bursting ignition is observed for 100% of the test batteries, ○: No bursting ignition is observed for 81-99% of the test batteries, Δ: Burst is observed for 61-80% of the test batteries Evaluation was made in each of four stages: no ignition was observed, x: burst ignition was not observed for 0 to 60% of the test batteries. The evaluation results of each test are shown in Table 2 below. Each test was performed with the number of tests n = 20.

Figure 0004688605
Figure 0004688605

表２に示すように、ダイヤフラム２２の中央部と周部との間に開裂溝３０を形成し（図６参照）、円環径ｂを排気口径ａより大きく設定した比較例１〜比較例３のリチウムイオン電池では、過充電試験で破裂発火が認められなかったものの、釘刺し試験や圧壊試験のような外部からの急激な変形を伴う破壊試験では破裂発火が起こった。これは、電池容量を１３Ａｈと高容量化していることから、変形時に電池内圧が急激に上昇し、反転したダイヤフラム２２が上蓋キャップ１の下部に張り付き開裂溝３０の開裂が妨げられたためと考えられる（図８参照）。これに対して、ダイヤフラム２の中央部に開裂溝８を形成し、円環径ｂを排気口径ａ以下（排気口径ａ≧円環径ｂ）に設定した実施例１〜実施例４のリチウムイオン電池５０では、過充電試験で破裂発火が認められなかったことはもちろん、釘刺し試験や圧壊試験でもほとんど破裂発火が認められなかった。これは、反転したダイヤフラム２が上蓋キャップ１に張り付いても、開裂溝８がほぼ確実に開裂し、電池内圧が排気口９を通じて電池外に開放されたためと考えられる（図４参照）。   As shown in Table 2, Comparative Example 1 to Comparative Example 3 in which a cleavage groove 30 is formed between the center portion and the peripheral portion of the diaphragm 22 (see FIG. 6), and the ring diameter b is set larger than the exhaust port diameter a. In the lithium ion battery, no bursting ignition was observed in the overcharge test, but bursting ignition occurred in a destructive test involving rapid external deformation such as a nail penetration test or a crush test. This is probably because the battery capacity has been increased to 13 Ah, so that the internal pressure of the battery suddenly increased during deformation, and the inverted diaphragm 22 stuck to the lower part of the upper lid cap 1 and the cleavage of the cleavage groove 30 was prevented. (See FIG. 8). On the other hand, the lithium ion of Examples 1 to 4 in which the cleavage groove 8 is formed in the center of the diaphragm 2 and the annular diameter b is set to the exhaust port diameter a or less (exhaust port diameter a ≧ annular diameter b). In the battery 50, no burst ignition was observed in the overcharge test, and almost no burst ignition was observed in the nail penetration test and crush test. This is considered to be because even when the inverted diaphragm 2 stuck to the upper lid cap 1, the cleavage groove 8 was almost certainly cleaved and the battery internal pressure was released outside the battery through the exhaust port 9 (see FIG. 4).

中でも、実施例３、実施例４のリチウムイオン電池５０では、円環径ｂ≦排気口径ａ≦貫通穴最小径ｃの関係に設定したため、開裂溝８が開裂した後でも、電池接続に使用したブスバ６０が障害となることなく電池内圧をスムーズに開放することができた。従って、リチウムイオン電池５０は、過充電時に安全性を確保することができるばかりではなく、釘刺しや圧壊等の急激な変形を伴う外力が作用しても安全性を確保することができることが判明した。   Among them, in the lithium ion batteries 50 of Example 3 and Example 4, since the relationship of the annular diameter b ≦ exhaust port diameter a ≦ through hole minimum diameter c was set, it was used for battery connection even after the cleavage groove 8 was cleaved. The battery internal pressure could be released smoothly without the bus bar 60 becoming an obstacle. Accordingly, it has been found that the lithium ion battery 50 can not only ensure safety when overcharged, but also ensure safety even when an external force accompanied by abrupt deformation such as nail penetration or crushing acts. did.

本発明は大容量をもつ電池において、急激な変形を伴う外力が作用しても安全性を確保することができる円筒型二次電池を提供するため、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。   The present invention contributes to the manufacture and sale of secondary batteries in order to provide a cylindrical secondary battery that can ensure safety even when an external force with sudden deformation is applied to a battery having a large capacity. Have industrial applicability.

本発明が適用可能な実施形態の円筒型リチウムイオン電池の断面図である。It is sectional drawing of the cylindrical lithium ion battery of embodiment which can apply this invention. 実施形態の円筒型リチウムイオン電池の上蓋の断面図である。It is sectional drawing of the upper cover of the cylindrical lithium ion battery of embodiment. 上蓋キャップに形成された排気口とダイヤフラムに形成された開裂溝との位置関係を示し、（Ａ）は上蓋の断面図であり、（Ｂ）はダイヤフラムの平面図である。The positional relationship of the exhaust port formed in the upper cover cap and the cleavage groove formed in the diaphragm is shown, (A) is a sectional view of the upper cover, and (B) is a plan view of the diaphragm. 電池異常時のダイヤフラム及び上蓋キャップを示す断面図である。It is sectional drawing which shows the diaphragm and upper cover cap at the time of battery abnormality. ブスバに形成された貫通穴と上蓋キャップに形成された排気口との位置関係を示し、（Ａ）はブスバの平面図であり、（Ｂ）はブスバの断面図であり、（Ｃ）は上蓋の断面図である。The positional relationship between the through hole formed in the bus bar and the exhaust port formed in the upper lid cap is shown, (A) is a plan view of the bus bar, (B) is a cross-sectional view of the bus bar, and (C) is the upper lid. FIG. 従来の円筒型リチウムイオン電池の上蓋の断面図である。It is sectional drawing of the upper cover of the conventional cylindrical lithium ion battery. 従来の円筒型リチウムイオン電池のダイヤフラムの平面図である。It is a top view of the diaphragm of the conventional cylindrical lithium ion battery. 従来の電池異常時のダイヤフラム及び上蓋キャップを示す断面図である。It is sectional drawing which shows the diaphragm and upper cover cap at the time of the conventional battery abnormality.

符号の説明Explanation of symbols

１ 上蓋キャップ
２ ダイヤフラム（導電性ダイヤフラム）
６ 接続板（接続部材）
８ 開裂溝
９ 排気口
１０ 電池缶（円筒状電池缶）
１１ 電極捲回群（電極群）
１３ ガスケット
２０ 上蓋
５０ 円筒型リチウムイオン電池（円筒型二次電池）
６０ ブスバ 1 Upper lid cap 2 Diaphragm (conductive diaphragm)
6 Connection plate (connection member)
8 Cleavage groove 9 Exhaust port 10 Battery can (cylindrical battery can)
11 Electrode winding group (electrode group)
13 Gasket 20 Upper lid 50 Cylindrical lithium ion battery (cylindrical secondary battery)
60 Busba

Claims (5)

所定圧で開裂する開裂溝が形成され皿状で中央に平面部を有する導電性ダイヤフラムと、周縁部が前記ダイヤフラムの周縁部に固定され中央に排気口が形成された凸部を有する上蓋キャップと、電極群を構成する正極及び負極のいずれか一方に電気的に接続され前記ダイヤフラム側に突出した中央の平面部が前記ダイヤフラムの前記電極群側の平面部に接合された接続部材とを有する上蓋を備え、前記上蓋がガスケットを介して円筒状電池缶にカシメ固定された大容量円筒型二次電池において、前記開裂溝は前記ダイヤフラムの平面部に形成されており、前記排気口は、中心が前記ダイヤフラムの前記開裂溝で画定される内側部分の中心と同軸線上に位置し、大きさが前記内側部分の大きさ以上であることを特徴とする円筒型二次電池。   A conductive diaphragm having a crevice groove formed to cleave at a predetermined pressure and having a flat surface in the center; and an upper lid cap having a convex portion with a peripheral edge fixed to the peripheral edge of the diaphragm and an exhaust port formed in the center; An upper lid having a central plane portion that is electrically connected to one of a positive electrode and a negative electrode constituting the electrode group and protrudes toward the diaphragm side, and is joined to a plane portion on the electrode group side of the diaphragm A large-capacity cylindrical secondary battery in which the upper lid is caulked and fixed to a cylindrical battery can via a gasket, the cleavage groove is formed in a flat portion of the diaphragm, and the exhaust port has a center A cylindrical secondary battery, wherein the cylindrical secondary battery is located on a coaxial line with a center of an inner portion defined by the cleavage groove of the diaphragm, and has a size equal to or larger than the size of the inner portion. 前記上蓋キャップの凸部には、前記円筒型二次電池同士を接続するためのブスバが接合されており、前記ブスバには中心が前記同軸線上に位置する貫通穴が形成されており、該貫通穴の大きさが前記排気口の大きさ以上であることを特徴とする請求項１に記載の円筒型二次電池。   A bus bar for connecting the cylindrical secondary batteries is joined to the convex portion of the upper lid cap, and a through hole whose center is located on the coaxial line is formed in the bus bar. The cylindrical secondary battery according to claim 1, wherein the size of the hole is equal to or larger than the size of the exhaust port. 前記排気口及び前記貫通穴は略円形で、前記開裂溝は円環状であり、前記排気口の最小径をＡ、前記開裂溝の円環外径をＢ、前記貫通穴の最小径をＣとしたときに、最小径Ｃ≧最小径Ａ≧円環外径Ｂであることを特徴とする請求項２に記載の円筒型二次電池。   The exhaust port and the through hole are substantially circular, the cleavage groove is annular, the minimum diameter of the exhaust port is A, the outer diameter of the ring of the cleavage groove is B, and the minimum diameter of the through hole is C. 3. The cylindrical secondary battery according to claim 2, wherein: minimum diameter C ≧ minimum diameter A ≧ annular outer diameter B. 4. 前記ダイヤフラムには、円環状の前記開裂溝から周縁部側に放射状の開裂溝が更に形成されていることを特徴とする請求項１乃至請求項３のいずれか１項に記載の円筒型二次電池。   The cylindrical secondary according to any one of claims 1 to 3, wherein the diaphragm is further formed with a radial cleavage groove on the peripheral side from the annular cleavage groove. battery. 前記開裂溝は、前記ダイヤフラムの前記上蓋キャップ側の平面部に形成されていることを特徴とする請求項１乃至請求項４のいずれか１項に記載の円筒型二次電池。   5. The cylindrical secondary battery according to claim 1, wherein the cleavage groove is formed in a planar portion of the diaphragm on the upper lid cap side. 6.
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JP2001068083A (en) * 1999-08-30 2001-03-16 Fuji Elelctrochem Co Ltd Explosionproof structure of cylindrical battery
JP2002358945A (en) * 2000-11-15 2002-12-13 Ngk Insulators Ltd Connection structure of lithium secondary unit cells
JP2004134204A (en) * 2002-10-10 2004-04-30 Shin Kobe Electric Mach Co Ltd Sealed type battery
JP2005011673A (en) * 2003-06-19 2005-01-13 Shin Kobe Electric Mach Co Ltd Sealed battery

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Publication number Priority date Publication date Assignee Title
JP2001068083A (en) * 1999-08-30 2001-03-16 Fuji Elelctrochem Co Ltd Explosionproof structure of cylindrical battery
JP2002358945A (en) * 2000-11-15 2002-12-13 Ngk Insulators Ltd Connection structure of lithium secondary unit cells
JP2004134204A (en) * 2002-10-10 2004-04-30 Shin Kobe Electric Mach Co Ltd Sealed type battery
JP2005011673A (en) * 2003-06-19 2005-01-13 Shin Kobe Electric Mach Co Ltd Sealed battery

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