JP5261884B2 - Lithium ion battery - Google Patents
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- JP5261884B2 JP5261884B2 JP2006087326A JP2006087326A JP5261884B2 JP 5261884 B2 JP5261884 B2 JP 5261884B2 JP 2006087326 A JP2006087326 A JP 2006087326A JP 2006087326 A JP2006087326 A JP 2006087326A JP 5261884 B2 JP5261884 B2 JP 5261884B2
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims description 66
- 229910001416 lithium ion Inorganic materials 0.000 title claims description 66
- 239000010410 layer Substances 0.000 claims description 66
- 239000004743 Polypropylene Substances 0.000 claims description 52
- 238000001514 detection method Methods 0.000 claims description 49
- 239000003792 electrolyte Substances 0.000 claims description 48
- 238000007789 sealing Methods 0.000 claims description 36
- 229920005989 resin Polymers 0.000 claims description 27
- 239000011347 resin Substances 0.000 claims description 27
- 239000002356 single layer Substances 0.000 claims description 23
- -1 polypropylene Polymers 0.000 claims description 20
- 230000002093 peripheral effect Effects 0.000 claims description 15
- 229920001155 polypropylene Polymers 0.000 claims description 14
- 238000009423 ventilation Methods 0.000 claims description 11
- 239000004698 Polyethylene Substances 0.000 claims description 10
- 229920006254 polymer film Polymers 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
- 229920000573 polyethylene Polymers 0.000 claims description 5
- 239000000853 adhesive Substances 0.000 claims description 4
- 230000001070 adhesive effect Effects 0.000 claims description 4
- 230000035699 permeability Effects 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 143
- 229910052751 metal Inorganic materials 0.000 description 20
- 239000002184 metal Substances 0.000 description 20
- 239000000463 material Substances 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 230000004888 barrier function Effects 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 7
- 239000011888 foil Substances 0.000 description 5
- 239000007774 positive electrode material Substances 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000011229 interlayer Substances 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
- 239000007773 negative electrode material Substances 0.000 description 3
- 239000012466 permeate Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 230000009172 bursting Effects 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000032798 delamination Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229920002239 polyacrylonitrile Polymers 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 206010039203 Road traffic accident Diseases 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000006183 anode active material Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- UQOULBWSWCWZJC-UHFFFAOYSA-N ethene;methyl hydrogen carbonate Chemical compound C=C.COC(O)=O UQOULBWSWCWZJC-UHFFFAOYSA-N 0.000 description 1
- 239000011245 gel electrolyte Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 229910003480 inorganic solid Inorganic materials 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000009545 invasion Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 150000002641 lithium Chemical group 0.000 description 1
- 150000002642 lithium compounds Chemical class 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 229910021437 lithium-transition metal oxide Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 229910052976 metal sulfide Inorganic materials 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 239000012945 sealing adhesive Substances 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- 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、電池内部で発生したガスを電池外部へ逃す安全弁及び電解質の漏洩を検知する機能を備えたリチウムイオン電池に関する。 The present invention relates to a safety valve for letting gas generated inside a battery escape to the outside of the battery and a lithium ion battery having a function of detecting leakage of electrolyte.
リチウムイオン電池とは、リチウム二次電池ともいわれ、液状、ゲル状および高分子ポリマー状の電解質を持ち、正極・負極活物質が高分子ポリマーからなるものを含むものである。このリチウムイオン電池は、充電時には正極活物質であるリチウム遷移金属酸化物中のリチウム原子（Ｌｉ）がリチウムイオン（Ｌｉ+）となって負極の炭素層間に入り込み（インターカレーション）、放電時にはリチウムイオン（Ｌｉ+）が炭素層間から離脱（デインターカレーション）して正極に移動し、元のリチウム化合物となることにより充放電反応が進行する電池である。 The lithium ion battery is also referred to as a lithium secondary battery, and includes a battery having a liquid, gel-like, and polymer-like electrolyte, and a positive electrode / negative electrode active material made of a polymer. In this lithium ion battery, the lithium atom (Li) in the lithium transition metal oxide, which is the positive electrode active material, is charged as lithium ion (Li + ) during charging and enters the carbon layer of the negative electrode (intercalation). This is a battery in which charge / discharge reaction proceeds when ions (Li + ) are desorbed (deintercalated) from the carbon layer and moved to the positive electrode to become the original lithium compound.
リチウムイオン電池の構成は、正極集電材（アルミニウム、ニッケル）／正極活性物質層（金属酸化物、カーボンブラック、金属硫化物、電解液、ポリアクリロニトリル等の高分子正極材料）／電解質層（プロピレンカーボネート、エチレンカーボネート、炭酸ジメチル、エチレンメチルカーボネート等のカーボネート系電解液、リチウム塩からなる無機固体電解質、ゲル電解質等）／負極活性物質層（リチウム金属、合金、カーボン、電解液、ポリアクリロニトリル等の高分子負極材料）／負極集電材（銅、ニッケル、ステンレス）及び、これらを包装する外装体からなる。 The composition of the lithium ion battery is as follows: positive electrode current collector (aluminum, nickel) / positive electrode active material layer (polymeric positive electrode material such as metal oxide, carbon black, metal sulfide, electrolyte, polyacrylonitrile) / electrolyte layer (propylene carbonate) , Carbonate electrolytes such as ethylene carbonate, dimethyl carbonate, ethylene methyl carbonate, inorganic solid electrolytes composed of lithium salts, gel electrolytes, etc.) / Anode active material layers (lithium metals, alloys, carbon, electrolytes, polyacrylonitrile, etc.) Molecular negative electrode material) / negative electrode current collector (copper, nickel, stainless steel) and an outer package for packaging them.
外装体としては、金属をプレス加工して円筒状または直方体状に容器化した金属製缶、あるいは、プラスチックフィルム、金属箔等のラミネートにより得られる複合フィルムからなる積層体を袋状にしたもの（以下、外装体）が挙げられる。従来、金属製缶が主に用いられていたが、金属製缶の容器外壁がリジッドであるため、電池自体の形状が決められてしまい、ハード側を電池に合わせ設計する必要があった。 As an exterior body, a metal can formed by pressing a metal into a cylindrical or rectangular parallelepiped container, or a laminate made of a composite film obtained by laminating a plastic film, a metal foil or the like in a bag shape ( Hereinafter, an exterior body) may be mentioned. Conventionally, metal cans have been mainly used. However, since the outer wall of the metal can container is rigid, the shape of the battery itself is determined, and the hardware side must be designed to match the battery.
そのため、近年、形状の自由度が高い積層体からなる外装体を用いる傾向にある。前記外装体の材質構成は、電池としての必要な物性、加工性、経済性等から、少なくとも基材層、バリア層、ヒートシール層と前記各層を接着する接着層からなり、必要に応じて中間層を設けることがある。前記構成の積層体からパウチを形成し、または、少なくとも片面をプレス成形して電池の収納部を形成して電池本体を収納し、パウチタイプまたは、エンボスタイプ（蓋体を被覆して）において、それぞれの周縁の必要部分をヒートシールにより電池とする。 Therefore, in recent years, there is a tendency to use an exterior body made of a laminate having a high degree of freedom in shape. The material structure of the exterior body is composed of at least a base material layer, a barrier layer, a heat seal layer and an adhesive layer that bonds the respective layers in view of necessary physical properties, workability, economy, etc. as a battery. A layer may be provided. A pouch is formed from the laminate having the above-described structure, or at least one side is press-molded to form a battery housing portion and a battery main body is housed. In a pouch type or an embossed type (covering a lid), A necessary part of each peripheral edge is made into a battery by heat sealing.
図６（ａ）は、ピロー状の外装体５を用いるパウチタイプのリチウムイオン電池の斜視図であり、図６（ｂ）はリチウムイオン電池を分解した状態を示す斜視図である。図６（ａ）及び（ｂ）に示すように、リチウムイオン電池１は、リチウムイオン電池本体２及び外装体５から構成されており、外装体５に収納されたリチウムイオン電池本体２は、その周縁を密封することにより、防湿性を確保している。 FIG. 6A is a perspective view of a pouch-type lithium ion battery using the pillow-shaped exterior body 5, and FIG. 6B is a perspective view showing a state in which the lithium ion battery is disassembled. As shown in FIGS. 6A and 6B, the lithium ion battery 1 is composed of a lithium ion battery body 2 and an exterior body 5, and the lithium ion battery body 2 housed in the exterior body 5 is By sealing the periphery, moisture resistance is secured.
図７は、エンボス部が形成されたトレイ５ａとシート５ｂとから成る外装体５を用いてリチウムイオン電池本体２を密封収納するエンボスタイプのリチウムイオン電池の斜視図である。 FIG. 7 is a perspective view of an embossed type lithium ion battery in which the lithium ion battery main body 2 is hermetically housed using the exterior body 5 including the tray 5a and the sheet 5b in which the embossed portion is formed.
リチウムイオン電池本体２は、正極活物質及び正極集電体から成る正極と、負極活物質及び負極集電体から成る負極と、正極及び負極間に充填される電解質と（いずれも図示せず）を含むセル（蓄電部）３と、セル３内の正極及び負極に連結されるとともに先端が外装体５の外部に突出するタブ（電極端子）４から構成されている。 The lithium ion battery body 2 includes a positive electrode composed of a positive electrode active material and a positive electrode current collector, a negative electrode composed of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode (none shown). And a tab (electrode terminal) 4 that is connected to a positive electrode and a negative electrode in the cell 3 and has a tip projecting outside the exterior body 5.
これら外装体において、外装体外部から外装体内部に水蒸気が浸入した場合、電解質と前記水蒸気との反応によりフッ化水素酸が生成し、デラミネーション（剥離）の発生を引き起こす。近年、この問題を解決するため、外装体は様々な積層構造が研究され密封性に優れ外部からの水蒸気の浸入を遮断するものが開発されている。 In these exterior bodies, when water vapor enters the exterior body from the outside of the exterior body, hydrofluoric acid is generated by the reaction between the electrolyte and the water vapor, causing delamination (peeling). In recent years, in order to solve this problem, various types of laminated bodies have been studied, and those having excellent sealing properties and blocking the entry of water vapor from the outside have been developed.
一方、外装体内部では、リチウムイオン電池の充放電により電解質と電極の間でイオンの交換がおこなわれており、この過程で少量の水素や酸素等が発生する場合がある。特に急速な充放電や過充電をした場合、ガスが発生し易く、これらのガスは充放電を繰り返すことで、徐々に外装体内部に蓄積し内圧を上昇する。 On the other hand, in the exterior body, ions are exchanged between the electrolyte and the electrodes by charging and discharging the lithium ion battery, and a small amount of hydrogen, oxygen, or the like may be generated in this process. In particular, when rapid charging / discharging or overcharging is performed, gases are likely to be generated, and these gases are repeatedly charged and discharged to gradually accumulate in the exterior body and increase the internal pressure.
内圧が上昇し続けた場合、最終的に外装体がその力に抗しきれず破裂し、外装体内部に充填された電解質は破裂と同時に飛び散り、リチウムイオン電池周辺の機器の故障や汚れにつながる。また、複数のリチウムイオン電池を接続して収納する場合、破裂の衝撃または、電解質の飛散により、隣接する他のリチウムイオン電池まで破損しかねない。 If the internal pressure continues to rise, the outer package will eventually burst without resisting the force, and the electrolyte filled in the outer package will scatter at the same time as the burst, leading to failure and contamination of the equipment around the lithium ion battery. In addition, when a plurality of lithium ion batteries are connected and stored, other adjacent lithium ion batteries may be damaged due to the impact of rupture or scattering of the electrolyte.
これまで、この問題を解決するため種々の提案がなされてきた。例えば、外装材に切り込み部を設け金属箔で塞ぐように接着することにより、ガス圧の上昇により外装体自体が破裂する前に前記金属箔を破断させるもの（特許文献１参照）や、シール部の一部に剥離強度の低い箇所を設け、ガス圧の上昇により当該箇所が剥離しガスを放出し外装体の破裂を防ぐもの（特許文献２参照）が挙げられる。 Until now, various proposals have been made to solve this problem. For example, by providing a cut portion in the exterior material and adhering it so as to close it with a metal foil, the metal foil is broken before the exterior body itself is ruptured due to an increase in gas pressure (see Patent Document 1), or a seal portion A part having a low peel strength is provided in a part of the film, and the part is peeled off by an increase in gas pressure to release gas and prevent the outer body from bursting (see Patent Document 2).
しかし、これらの発明は、ガスを放出する部分のシール強度が不十分であるため、外装体内部の気密性が低下し水蒸気の浸入の原因となっていた。また、ガスの放出とともに電解質も漏洩するため周辺機器を汚す可能性があった。
本発明は上記問題点に鑑み、複合フィルムからなる積層体を外装体に用いて、外装体内部の気密性と水蒸気バリア性を十分確保するとともに、内部のガスを逃がすことにより内圧の上昇による外装体の破裂を防止する機能を有し、ガスとともに電解質が漏洩した場合は、漏洩を検知することができるリチウムイオン電池を提供することを目的とする。 In view of the above-mentioned problems, the present invention uses a laminate made of a composite film for an exterior body to ensure sufficient airtightness and water vapor barrier properties inside the exterior body and to release the internal gas to increase the internal pressure. An object of the present invention is to provide a lithium ion battery that has a function of preventing body rupture and can detect leakage when an electrolyte leaks together with gas.
上記目的を達成するために本発明の構成は、正極と負極と、前記正極及び負極間に充填される電解質とを含むリチウムイオン電池本体を、最内層にシール層を有する積層体からなる外装体に封入し前記外装体の周縁部を密封シールして成るリチウムイオン電池において、前記外装体の周縁部の一部に外装体内部で発生したガスを外装体外部に逃すための安全弁を設け、該安全弁が外装体内部のガス圧が所定値を超えたとき開く弁部と、ガスのみを透過するガス透過部と、前記弁部から前記ガス透過部へガスを導くガス通気路とで構成され、前記弁部と前記ガス透過部がそれぞれ前記ガス通気路を介して外装体内側と外装体外側に配され、前記ガス通気路に電解質の漏れを検知するための検知タブを設けたことを特徴とするリチウムイオン電池である。 In order to achieve the above object, the structure of the present invention comprises a lithium ion battery main body comprising a positive electrode, a negative electrode, and an electrolyte filled between the positive electrode and the negative electrode, and an outer package comprising a laminate having a seal layer as the innermost layer. In a lithium ion battery that is sealed in and sealed at the periphery of the exterior body, a safety valve is provided at a part of the periphery of the exterior body to release gas generated inside the exterior body to the outside of the exterior body, The safety valve is configured by a valve portion that opens when the gas pressure inside the exterior body exceeds a predetermined value, a gas permeable portion that allows only gas to pass through, and a gas ventilation path that guides gas from the valve portion to the gas permeable portion. The valve portion and the gas permeation portion are respectively disposed on the inner side of the exterior body and the outer side of the exterior body through the gas ventilation path, and a detection tab for detecting leakage of electrolyte is provided in the gas ventilation path. Lithium ion battery A.
本発明は上記構成のリチウムイオン電池において、前記弁部と前記ガス透過部が前記外装体の周縁部に挟持され密封シールされることにより安全弁が形成されることを特徴とする。 According to the present invention, in the lithium ion battery having the above-described configuration, a safety valve is formed by sandwiching and sealingly sealing the valve portion and the gas permeable portion on a peripheral edge portion of the exterior body.
本発明は上記構成のリチウムイオン電池において、前記検知タブが、前記ガス透過部と前記外装体に挟持され密封シールされることを特徴とする。 According to the present invention, in the lithium ion battery having the above-described configuration, the detection tab is sandwiched and hermetically sealed between the gas permeable portion and the exterior body.
本発明は上記構成のリチウムイオン電池において、前記弁部がシールされた前記外装体の周縁部より内側に突出した形状であり、前記シール層よりも接着強度の低いシール樹脂で構成されていることを特徴とする。 In the lithium ion battery having the above-described configuration, the present invention is configured such that the valve portion protrudes inward from the peripheral edge portion of the sealed outer body and is made of a seal resin having lower adhesive strength than the seal layer. It is characterized by.
本発明は上記構成のリチウムイオン電池において、前記シール層がポリプロピレンで構成され、且つシール樹脂がポリプロピレンとポリエチレンを含むブレンド樹脂で構成されていること特徴とする。 According to the present invention, in the lithium ion battery having the above-described configuration, the sealing layer is made of polypropylene, and the sealing resin is made of a blend resin containing polypropylene and polyethylene.
本発明は上記構成のリチウムイオン電池において、前記ガス透過部が気体のみを透過する高分子フィルムで構成され、前記安全弁の開口部を塞ぐように配置されていることを特徴とする。 The present invention is characterized in that, in the lithium ion battery having the above-described configuration, the gas permeable portion is formed of a polymer film that allows only gas to pass through, and is disposed so as to close the opening of the safety valve.
本発明は上記構成のリチウムイオン電池において、前記高分子フィルムが折り曲げられた構造をとることを特徴とする。 The present invention is a lithium ion battery having the above-described configuration, wherein the polymer film is bent.
本発明は上記構成のリチウムイオン電池において、前記高分子フィルムがポリプロピレン単層フィルムであることを特徴とする。 According to the present invention, in the lithium ion battery configured as described above, the polymer film is a polypropylene single layer film.
本発明の第１の構成によると、外装体の周縁部の一部に外装体内部で発生したガスを外装体外部に逃すための安全弁を設け、安全弁が外装体内部のガス圧が所定値を超えたとき開く弁部と、ガスのみを透過するガス透過部で構成され、弁部とガス透過部をそれぞれガス通気路を介して外装体内側と外装体外側に配し、ガス通気路に電解質の漏れを検知するための検知タブを設けたことにより、ガス圧が一定の間は、弁部により外装体内部の気密性が確保され外部からの水蒸気の浸入を防ぐことができる。また、ガス圧が上昇し弁部が開いた後は、ガス透過部においてガスが透過されるため、ガス圧の上昇を抑え外装体の破裂を防ぐ。このとき、ガス透過部はガスのみを透過し電解質を透過しないため電解質の漏洩を防ぐことができる。 According to the first configuration of the present invention, the safety valve for releasing the gas generated inside the exterior body to the outside of the exterior body is provided in a part of the peripheral portion of the exterior body, and the safety valve has a predetermined value of the gas pressure inside the exterior body. Consists of a valve part that opens when exceeded and a gas permeable part that allows only gas to pass through. By providing a detection tab for detecting the leakage of gas, the valve portion ensures airtightness inside the exterior body while the gas pressure is constant, and can prevent water vapor from entering from the outside. Further, after the gas pressure rises and the valve portion opens, gas is permeated through the gas permeation portion, so that the increase in gas pressure is suppressed and the outer body is prevented from bursting. In this case, the gas permeable portion can prevent electrolyte leakage for not transmitting the transmitted electrolytic electrolyte only gas.
また、検知タブに検知装置を接続することにより、弁部が開いた際、ガス透過部側へ押し出される電解質を検知することができる。これにより、弁部が開いたことを確認することができ外装体内部のガス圧が所定値に達したことがわかる。 Further, by connecting a detection device to the detection tab, it is possible to detect the electrolyte pushed out to the gas permeable portion side when the valve portion is opened. Thereby, it can confirm that the valve part opened and it turns out that the gas pressure inside an exterior body reached the predetermined value.
本発明の第２の構成によると、弁部とガス透過部が前記外装体の周縁部に挟持され密封シールされることにより安全弁が形成されるため、新たに安全弁を構成する部品が簡易なものとなる。このため製造コストを抑えることができる。また、外装体に挟持して密封シールするだけであるので製造工程も従来のままで、安全弁付きのリチウムイオン電池を製造することができる。 According to the second configuration of the present invention, the valve part and the gas permeable part are sandwiched between the outer peripheral parts of the exterior body and hermetically sealed to form a safety valve, so that the parts constituting the safety valve are newly simplified. It becomes. For this reason, manufacturing cost can be held down. In addition, since it is only sandwiched between the outer package and hermetically sealed, the lithium ion battery with a safety valve can be manufactured with the same manufacturing process.
本発明の第３の構成によると、検知タブが、ガス透過部と外装体に挟持され密封シールされることで検知タブを容易に設けることができる。また、外装体内部の気密性も確保することができる。 According to the third configuration of the present invention, the detection tab can be easily provided by being sandwiched and sealed between the gas permeable portion and the exterior body. Moreover, the airtightness inside an exterior body can also be ensured.
本発明の第４の構成によると、シールされた外装体の周縁部より内側に突出した形状の弁部を外装体最内層に設けられたシール層よりも接着強度の低いシール樹脂で構成することにより、外装体内部でガスが発生し、内圧が上昇したとき外装体周縁部のシール層が剥れる前に弁部のシール樹脂が剥れる。これにより、ガスは弁部を通りガス透過部において外装体外部へ放出される。このとき、電解質はガス透過部で遮断され外部へ漏洩しない。仮に、外装体周縁部のシール層が剥れた場合、その箇所からガスとともに電解質が外部へ漏れ出るが、本発明の構成によりガスのみをガス透過部より放出するため外装体内部のガス圧が下がり、外装体周縁部のシール層の剥れを防ぐことができる。また、弁部のシール樹脂が剥れた際、検知タブが電解質を検知するためシール樹脂が剥れたことを知ることができる。 According to the fourth configuration of the present invention, the valve portion having a shape protruding inward from the peripheral edge portion of the sealed exterior body is configured with a seal resin having lower adhesive strength than the seal layer provided in the innermost layer of the exterior body. As a result, gas is generated inside the exterior body, and when the internal pressure rises, the seal resin on the valve portion is peeled off before the seal layer on the periphery of the exterior body is peeled off. As a result, the gas passes through the valve portion and is released to the outside of the exterior body at the gas permeable portion. At this time, the electrolyte is blocked by the gas permeable portion and does not leak to the outside. If the seal layer on the outer periphery of the outer package is peeled off, the electrolyte leaks out of the gas together with the gas, but the gas pressure inside the outer package is increased because only the gas is released from the gas permeation unit according to the configuration of the present invention. It can fall and it can prevent peeling of the seal layer of a peripheral part of an exterior body. Further, when the sealing resin of the valve portion is peeled off, the detection tab detects the electrolyte, so that it can be known that the sealing resin has been peeled off.
本発明の第５の構成によると、外装体最内層に設けられたシール層をポリプロピレンで構成し、弁部を構成するシール樹脂をポリプロピレンとポリエチレンを含むブレンド樹脂で構成することにより、ヒートシールする場合シール層と弁部が同程度の融点を有するため、融着させ易い。また、ポリプロピレンとポリエチレンの配合を変えることにより、シール強度を調整することができる。これにより、弁部が開く内圧の所定値も調節が可能となる。 According to the fifth configuration of the present invention, the seal layer provided in the innermost layer of the exterior body is made of polypropylene, and the seal resin constituting the valve portion is made of a blend resin containing polypropylene and polyethylene, thereby heat-sealing. In this case, since the sealing layer and the valve portion have the same melting point, they are easily fused. Also, the seal strength can be adjusted by changing the blending of polypropylene and polyethylene. Thereby, the predetermined value of the internal pressure at which the valve portion opens can also be adjusted.
本発明の第６の構成によると、ガス透過部が気体のみを透過する高分子フィルムを外装体に挟持して密封シールするのみでガス透過部を形成することができる。 According to the sixth configuration of the present invention, the gas permeable portion can be formed only by sandwiching and sealing the polymer film through which the gas permeable portion transmits only gas.
本発明の第７の構成によると、ガス透過部を形成するフィルムを折り曲げることによりガス透過部におけるフィルムの表面積が大きくなりガス透過部から外装体外部へ放出できるガス量が上昇する。また、ガス透過部の省スペース化を図ることができる。 According to the seventh configuration of the present invention, by bending the film forming the gas permeable portion, the surface area of the film in the gas permeable portion is increased, and the amount of gas that can be discharged from the gas permeable portion to the exterior of the exterior body is increased. Moreover, space saving of a gas permeation | transmission part can be achieved.
本発明の第８の構成によると、ガス透過部を形成するフィルムにポリプロピレン単層フィルムを用いることにより、外装体最内層に設けられたシール層がポリプロピレンで構成されている場合、同じ物質で構成されているためヒートシールによるシール強度が高い。また、ポリプロピレンはガス透過性を有し、液体を透過させないため、ガス透過部として好適な基材である。また、金属基材とのシール性も有するため検知タブに金属基材を用いた場合でも、外装体５とポリプロピレン単層フィルムの間に検知タブを挟持して、密封シールすることができる。 According to the 8th structure of this invention, when the sealing layer provided in the outermost body inner layer is comprised with a polypropylene by using a polypropylene single layer film for the film which forms a gas permeation | transmission part, it is comprised with the same substance. Therefore, the sealing strength by heat sealing is high. Polypropylene is a base material suitable as a gas permeable part because it has gas permeability and does not allow liquid to permeate. Moreover, since it also has a sealing property with a metal base material, even when a metal base material is used for the detection tab, the detection tab can be sandwiched between the outer package 5 and the polypropylene single-layer film and hermetically sealed.
以下、本発明の実施形態について図面を参照しながら説明する。本発明では外装体内部に蓄積されたガスを放出する安全弁を設け外装体の破裂を未然に防止するとともに、外部からの水蒸気の浸入を有効に防ぎ、電解質の飛散を防止するリチウムイオン電池を提供しようとするものである。また、リチウムイオン電池は、リチウムイオン電池本体を包装する外装体のタイプにより、パウチタイプと、エンボスタイプとがあり、本発明はいずれのタイプにも適用することができる。なお、従来例の図６、図７と共通する部分には同一の符号を付して説明を省略する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention provides a lithium-ion battery that is provided with a safety valve that discharges gas accumulated in the exterior body to prevent the exterior body from rupturing, effectively prevents water vapor from entering from the outside, and prevents the electrolyte from scattering. It is something to try. Moreover, there are a lithium ion battery in a pouch type and an embossed type depending on the type of the outer package that wraps the lithium ion battery main body, and the present invention can be applied to any type. In addition, the same code | symbol is attached | subjected to the part which is common in FIG. 6, FIG. 7 of a prior art example, and description is abbreviate | omitted.
図１（ａ）は本発明に係るリチウムイオン電池１の概略平面図であり、図１（ｂ）は安全弁６近傍を拡大して示すものである。安全弁６は図１（ａ）で示されるようにリチウムイオン電池１の正極と負極のタブ材４の中間付近に設けられている。これは、リチウムイオン電池１の収納効率を上げるために最も好適な配置であり、使用態様又はリチウムイオン電池１の収納スペースに応じてタブ材の中間付近以外に配すことも可能である。 FIG. 1A is a schematic plan view of a lithium ion battery 1 according to the present invention, and FIG. As shown in FIG. 1A, the safety valve 6 is provided in the vicinity of the middle between the positive electrode and negative electrode tab members 4 of the lithium ion battery 1. This is the most suitable arrangement for increasing the storage efficiency of the lithium ion battery 1, and can be arranged other than the middle of the tab material depending on the use mode or the storage space of the lithium ion battery 1.
安全弁６は外装体内側に設けられた弁部９と外装体外側に設けられたガス透過部７で構成され、弁部９とガス透過部７の間にはガス通気路８が設けられガスの通路が確保されている。また、検知タブ１５の検知装置１６（図５参照）と接続される部分は外装体外部へ突出し、電解質の漏れを検知する端部１５ａはガス通気路８内に配置されている。 The safety valve 6 is composed of a valve portion 9 provided inside the exterior body and a gas permeation portion 7 provided outside the exterior body, and a gas ventilation path 8 is provided between the valve portion 9 and the gas permeation portion 7 so as to prevent gas from flowing. A passage is secured. The portion to be connected to the detector 16 of the detecting tab 15 (see FIG. 5) end portion 15a for detecting the leakage of the exterior body protrudes to the outside, electrolytic electrolyte is disposed in the gas vent passage 8.
また、図１（ｂ）に示されるように安全弁６を上方から見た場合、ガス透過部７と弁部９を外装体５の所定の位置に挟持させ上下から加圧及び加熱し、ヒートシールするのみで本発明にかかる安全弁６を形成することができる。また、検知タブ１５の電解質の漏れを検知する端部１５ａをガス透過部７と弁部９の間に配し、ガス透過部７と外装体５で、検知タブ１５を挟持しヒートシールすれば、弁部９とガス透過部７と検知タブ１５が一体となったリチウムイオン電池１を構成することができる。このとき、外装体５のガス透過部７と弁部９を挟持する部分はヒートシールしても良いが、ガス透過部７と弁部９の間はガス通気路８となる空間を形成する必要があるため、ヒートシールしてはならない。もし、この領域をヒートシールして外装体５の上面と下面がシールされた場合、弁部９が開いてもガスはガス透過部７へ達することができないため、安全弁６の効果を発揮することができない。また、検知タブ１５の端部１５ａも外装体５の上面と下面にシールされないようガス通気路８に配置する必要がある。 Further, as shown in FIG. 1B, when the safety valve 6 is viewed from above, the gas permeable portion 7 and the valve portion 9 are sandwiched between predetermined positions of the exterior body 5 and pressurized and heated from above and below, and heat sealing is performed. The safety valve 6 according to the present invention can be formed only by doing this. Further, an end 15a for detecting leakage of electrolyte in the detection tab 15 is arranged between the gas permeable portion 7 and the valve portion 9, and the detection tub 15 is sandwiched between the gas permeable portion 7 and the exterior body 5 and heat sealed. The lithium ion battery 1 in which the valve part 9, the gas permeation part 7, and the detection tab 15 are integrated can be configured. At this time, the portion of the exterior body 5 that sandwiches the gas permeable portion 7 and the valve portion 9 may be heat-sealed, but it is necessary to form a space that becomes the gas ventilation path 8 between the gas permeable portion 7 and the valve portion 9. There must be no heat sealing. If this area is heat sealed and the upper and lower surfaces of the outer package 5 are sealed, the gas cannot reach the gas permeation section 7 even if the valve section 9 is opened. I can't. Moreover, it is necessary to arrange | position the edge part 15a of the detection tab 15 in the gas ventilation path 8 so that it may not be sealed by the upper surface and lower surface of the exterior body 5. FIG.
図２は図１（ａ）の矢印ｘ方向からみたリチウムイオン電池１の概略正面図であり、図２（ａ）はヒートシール前の状態を示し、図２（ｂ）はヒートシール後の状態を示す。 2 is a schematic front view of the lithium ion battery 1 seen from the direction of the arrow x in FIG. 1 (a), FIG. 2 (a) shows a state before heat sealing, and FIG. 2 (b) shows a state after heat sealing. Indicates.
図２（ｂ）に示されるようにガス透過部７は外装体５の外側に面するように配されている。これにより弁部９が開いたとき外装体内部のガスはガス透過部７を透過し外装体５の外側へ放出される。また、検知タブ１５はガス透過部７周縁部より外装体外部へ突出している。これは、検知タブ１５が、ガス透過部７と外装体５に挟持され、シールされているからである。また、ガス透過部７及び検知タブ１５の周縁部は外装体５と密封シールされ、ガス透過部７を介すことなく外装体内部のガスは外部へ漏れ出ることはない。したがって、ガス透過部７にガス透過性を有する高分子フィルムを用いる場合、安全弁６（図1参照）により形成される開口部を塞ぐように配置しなければならない。 As shown in FIG. 2B, the gas permeable part 7 is arranged so as to face the outside of the outer package 5. As a result, when the valve portion 9 is opened, the gas inside the exterior body passes through the gas permeable portion 7 and is released to the outside of the exterior body 5. The detection tab 15 protrudes from the outer periphery of the gas permeable portion 7 to the outside of the exterior body. This is because the detection tab 15 is sandwiched and sealed between the gas permeable portion 7 and the exterior body 5. Moreover, the gas permeation | transmission part 7 and the peripheral part of the detection tab 15 are sealed with the exterior body 5, and the gas inside an exterior body does not leak outside without passing the gas permeation | transmission part 7. FIG. Therefore, when a polymer film having gas permeability is used for the gas permeable portion 7, it must be disposed so as to close the opening formed by the safety valve 6 (see FIG. 1).
外装体内側に設けられた弁部９は、ガス内部の圧力が所定値に達するまで外装体内部を閉弁し気密性を確保している。また、外装体外部からの水蒸気の浸入を防ぐために一定のバリア性が必要である。一方、内圧が所定値を超えたとき弁部９は開きガスの通気口を形成する。このとき、内圧の力で外装体内部のガスとともに電解質もガス透過部７側へ押し出される。また、この電解質は、検知タブ１５の端部１５ａ（図１（ｂ）参照）に接触したとき検知装置１６（図５参照）に検知される。 The valve portion 9 provided inside the exterior body closes the interior of the exterior body until the internal pressure of the gas reaches a predetermined value to ensure airtightness. In addition, a certain barrier property is required to prevent the intrusion of water vapor from the exterior of the exterior body. On the other hand, when the internal pressure exceeds a predetermined value, the valve portion 9 opens to form a gas vent. At this time, the electrolyte is pushed out to the gas permeable portion 7 side together with the gas inside the outer casing by the force of the internal pressure. The electrolyte is detected by the detection device 16 (see FIG. 5) when it contacts the end 15a of the detection tab 15 (see FIG. 1B).
外装体外側に設けられたガス透過部７は、弁部９が開きガス通気路８を通って外装体外部へ抜け出ようとする電解質を遮断し外部への漏洩を防ぐ。したがって、ガス透過部７に高分子フィルムを用い、弁部９にシール樹脂を用いる場合、高分子フィルムはシール樹脂と比較して外装体５と高いシール強度を持つ必要がある。つまり、弁部９に設けられた樹脂が内圧の上昇により凝集破壊することで弁部９が開くため、高分子フィルムと外装体５とのシール強度が低いとその内圧で高分子フィルムも凝集破壊し、ガス透過部７から電解質がガスとともに噴出する恐れがある。 The gas permeation section 7 provided outside the exterior body blocks the electrolyte that attempts to escape from the exterior body through the gas ventilation path 8 by opening the valve section 9 and prevents leakage to the outside. Therefore, when a polymer film is used for the gas permeable portion 7 and a seal resin is used for the valve portion 9, the polymer film needs to have higher sealing strength with the outer package 5 than the seal resin. That is, since the resin provided in the valve portion 9 is cohesively broken due to an increase in internal pressure, the valve portion 9 is opened. In addition, the electrolyte may be ejected from the gas transmission part 7 together with the gas.
また、ガス透過部７は電解質を遮断しガスのみを透過するため、ガスを外装体外部へ放出して外装体内部のガス圧を下げる役割を果たす。これにより、内圧の上昇により弁部９が凝集破壊した後も電解質の漏洩を防ぐことができる。 Moreover, since the gas permeation | transmission part 7 interrupts | blocks an electrolyte and permeate | transmits only gas, it plays the role which discharge | releases gas to the exterior body exterior and reduces the gas pressure inside an exterior body. Thereby, leakage of the electrolyte can be prevented even after the valve portion 9 is cohesively broken due to an increase in internal pressure.
ガス透過部７と弁部９の間に電解質を検知する端部１５ａが配置される検知タブ１５は検知装置１６と接続することで弁部９の凝集破壊を検知することができる。これは、弁部９の凝集破壊により外装体内部から押し出される電解質を検知することによるものである。これにより、外装体内部のガス圧が所定値を超えていることが予測できる。 The detection tab 15 in which the end 15a for detecting the electrolyte is disposed between the gas permeable portion 7 and the valve portion 9 can be connected to the detection device 16 to detect cohesive failure of the valve portion 9. This is due to the detection of the electrolyte pushed out from the inside of the exterior body due to the cohesive failure of the valve portion 9. Thereby, it can be predicted that the gas pressure inside the exterior body exceeds a predetermined value.
電気自動車などにリチウムイオン電池を搭載しモーターを駆動させる場合、省スペース化や高出力を実現するため複数のリチウムイオン電池を複数並べ収納ケースに収納する必要がある。このときリチウムイオン電池の外装体５が破裂すると周辺のリチウムイオン電池を破損させるだけでなく、強酸性、強アルカリ性の電解質が漏れ出しショート等が原因で発火する可能性がある。 When a lithium ion battery is mounted on an electric vehicle or the like to drive a motor, it is necessary to store a plurality of lithium ion batteries in a storage case in order to save space and achieve high output. At this time, if the outer package 5 of the lithium ion battery ruptures, not only the surrounding lithium ion battery is damaged, but a strong acidic or strong alkaline electrolyte may leak out and ignite due to a short circuit or the like.
また、走行中にこれらリチウムイオン電池の破裂が起こった場合、車両の故障にとどまらず自動車事故等、２次災害につながる危険性もある。したがって、リチウムイオン電池の破裂を高精度に防ぐ必要がある。 In addition, if these lithium ion batteries rupture during running, there is a risk of not only a vehicle failure but also a secondary disaster such as an automobile accident. Therefore, it is necessary to prevent rupture of the lithium ion battery with high accuracy.
次にガス透過部７、弁部９及び検知タブ１５について具体的に説明する。図３（ａ）は図１（ａ）の安全弁をＡ−Ａ‘方向からみた横断面図である。安全弁６において弁部９は外装体内側、ガス透過部７は外装体外側に直列的に配されている。また、検知タブ１５は検知タブ１５の電解質を検知する端部１５ａが弁部９とガス透過部７の間に配置されるよう設けられている。これにより弁部９が開きガス透過部７側へ電解質が押し出されたとき、電解質は端部１５ａに付着する。このとき、検知装置１６（図５参照）が電解質を検知する。 Next, the gas permeable part 7, the valve part 9, and the detection tab 15 will be described in detail. FIG. 3A is a cross-sectional view of the safety valve of FIG. 1A viewed from the A-A ′ direction. In the safety valve 6, the valve portion 9 is arranged in series on the inside of the exterior body, and the gas permeable portion 7 is arranged in series on the outside of the exterior body. The detection tab 15 is provided so that an end 15 a for detecting the electrolyte of the detection tab 15 is disposed between the valve portion 9 and the gas permeable portion 7. Thereby, when the valve part 9 opens and the electrolyte is pushed out to the gas permeation part 7 side, the electrolyte adheres to the end part 15a. At this time, the detection device 16 (see FIG. 5) detects the electrolyte.
弁部９は、外装体５に上下に挟持された状態でシールしている。このため、内圧が所定値に達するまでは、外装体内部は高い気密性を保ち、外部からの水蒸気の浸入に対しても高いバリア性を有する。 The valve part 9 is sealed in a state of being sandwiched up and down by the exterior body 5. Therefore, until the internal pressure reaches a predetermined value, the outer package interior maintaining high air-tightness, it has a high barrier property against penetration of water vapor from the outside.
また、弁部９を構成する基材としてはポリプロピレン（以下ＰＰと略す）とポリエチレン（以下ＰＥと略す）のブレンド樹脂が用いられる。この樹脂はＰＥをブレンドすることによりＰＰ樹脂と比較して強度が弱くなる。したがって、外装体５最内層のヒートシール層にＰＰ層を用いた場合、外装体５が重なりＰＰ層間でシールされる外装体周縁部５ａと比較してＰＰ層とブレンド樹脂のシール強度は低下する。これにより、外装体内部でガスが蓄積され外装体５が膨張し外装体５上面と外装体５下面を引き剥がす圧力がかかったとき、ブレンド樹脂のシール部分が外装体周縁部５ａのシール部分より先に剥離する。 As the base material constituting the valve portion 9, a blend resin of polypropylene (hereinafter abbreviated as PP) and polyethylene (hereinafter abbreviated as PE) is used. This resin becomes weaker than PE resin by blending PE. Therefore, when a PP layer is used as the innermost heat seal layer of the outer package 5, the sealing strength of the PP layer and the blended resin is lower than that of the outer package periphery 5 a where the outer package 5 overlaps and is sealed between the PP layers. . As a result, when gas is accumulated in the exterior body and the exterior body 5 expands and pressure is applied to peel off the upper surface of the exterior body 5 and the lower surface of the exterior body 5, the seal portion of the blend resin is more than the seal portion of the outer periphery portion 5 a. Peel off first.
これにより、外装体周縁部５ａからガスとともに電解質が外装体外部へ漏洩することを防ぎ、ガスおよび電解質をガス透過部７へ導くことができる。その後、ガス透過部７においてガスのみを外装体外部へ放出し内圧を下げることで外装体５の破裂および電解質の漏洩を防ぐことができる。また、弁部９の凝集破壊後、検知タブ１５が電解質を検知することにより、外装体外部から外装体内部における弁部９の凝集破壊を知ることができる。これにより、前もって外装体５の破裂に対処することができる。 Thereby, it is possible to prevent the electrolyte from leaking from the outer periphery of the exterior body 5 a together with the gas to the outside of the exterior body, and to guide the gas and the electrolyte to the gas permeable portion 7. Thereafter, the gas permeation section 7 releases only the gas to the outside of the exterior body and lowers the internal pressure, thereby preventing the exterior body 5 from rupturing and electrolyte leakage. Further, after the cohesive failure of the valve portion 9, the detection tab 15 detects the electrolyte, so that the cohesive failure of the valve portion 9 inside the exterior body can be known from the outside of the exterior body. Thereby, it is possible to cope with the rupture of the outer package 5 in advance.
また、弁部９と外装体５のシール強度が低過ぎる場合、外装体内部の気密性が確保されず外部からの蒸気の浸入を招き易い。また、弁部９のシール強度が高過ぎる場合、外装体内部の圧力が相当高くなった状態で弁部９が凝集破壊され、その衝撃でガス透過部７も破裂する可能性がある。したがって弁部９には、強度の高いＰＰと強度の低いＰＥの構成比率を調整し好適な強度のブレンド樹脂を用いる必要がある。なお、弁部９は内圧が上昇したときに外装体周縁部５ａのシール部より先に剥離させる必要がある。このため図２（ｂ）に示すようにシールされた外装体周縁部５ａよりも先端を外装体内側に突出した形状とすることが好ましい。 Moreover, when the sealing strength of the valve part 9 and the exterior body 5 is too low, the airtightness inside the exterior body is not ensured, and the invasion of vapor from the outside is likely to occur. Moreover, when the sealing strength of the valve part 9 is too high, the valve part 9 may be coherently broken while the pressure inside the exterior body is considerably high, and the gas permeable part 7 may also be ruptured by the impact. Therefore, it is necessary to use a blend resin having a suitable strength by adjusting the constituent ratio of PP having high strength and PE having low strength. In addition, when the internal pressure rises, it is necessary to peel the valve part 9 ahead of the seal part of the outer periphery part 5a. For this reason, as shown in FIG.2 (b), it is preferable to set it as the shape which protruded the front-end | tip rather than the sealed exterior body peripheral part 5a.
ガス透過部７は図３に示すように蛇腹状に折込まれたＰＰ単層フィルム１０で構成することができる。このとき、ＰＰ単層フィルム１０の上端部１０ａは外装体５内面にシールされ、ＰＰ単層フィルム１０の下端部１０ｂと外装体５内面は検知タブ１５を挟持してシールされ、外装体内部の気密性が確保されている。これにより、ＰＰ単層フィルム１０はガスを透過させるための一定の表面積を確保した上で安全弁６における開口部を密封シールすることができる。なお、図示されていないがＰＰ単層フィルムの幅方向における両端も外装体５に挟持され密封シールされている。 The gas permeation | transmission part 7 can be comprised with PP single layer film 10 folded in the shape of a bellows as shown in FIG. At this time, the upper end portion 10a of the PP single layer film 10 is sealed to the inner surface of the exterior body 5, the lower end portion 10b of the PP single layer film 10 and the inner surface of the exterior body 5 are sealed with the detection tab 15 interposed therebetween, and Airtightness is ensured. Thereby, the PP single layer film 10 can seal the opening of the safety valve 6 while ensuring a certain surface area for allowing gas to permeate. Although not shown, both ends of the PP single layer film in the width direction are also sandwiched and sealed by the outer package 5.
また、ＰＰは熱融着性であり、外装体５の最内層をＰＰ層で構成した場合、ガス透過部７と外装体５のヒートシール層が同質で融点が等しく親和性が高いため、シール強度に優れ外装体内部の高い気密性を確保することができる。また、金属基材との接着性も有するため、金属基材で構成される検知タブ１５を挟持して外装体５とシールしても外装体内部の気密性は失われない。なお、ＰＰとのシール強度を向上させるため、予め検知タブ１５の表面に熱融着性樹脂を被覆したものを用いてもよい。 Also, PP is heat-fusible, and when the innermost layer of the outer package 5 is composed of a PP layer, the heat-seal layer of the gas permeable portion 7 and the outer package 5 are the same and have the same melting point and high affinity. Excellent strength and high airtightness inside the exterior body can be secured. Moreover, since it has adhesiveness with a metal base material, even if the detection tab 15 comprised with a metal base material is pinched and it seals with the exterior body 5, the airtightness inside an exterior body is not lost. In addition, in order to improve the sealing strength with PP, the surface of the detection tab 15 previously coated with a heat-fusible resin may be used.
また、ＰＰ単層フィルム１０を蛇腹状に構成した場合、ガス透過面積が広がりガス透過部７から外部へ放出するガス量を増加させるためである。これにより、内圧の上昇をいっそう防ぐことができる。なお、ＰＰ単層フィルムの形状は特に蛇腹状に限定するものではなく、ガス透過のための表面積が十分確保され、安全弁６における開口部を塞ぎ密封シールするものであれば、一つ折り又は折り曲げられていないものでもよい。 In addition, when the PP single layer film 10 is formed in a bellows shape, the gas permeation area is increased and the amount of gas released from the gas permeation part 7 to the outside is increased. Thereby, the rise of internal pressure can be prevented further. The shape of the PP single-layer film is not particularly limited to a bellows shape, and can be folded or folded as long as a sufficient surface area for gas permeation is secured and the opening in the safety valve 6 is closed and hermetically sealed. It may not be.
また、外装体５の最内層をＰＰ層で構成した場合、外装体内部で発生したガスはガス透過部７以外に、外装体周縁部５ａ（図１（ａ）参照）からも放出される。図４は、図１（ａ）で示されるリチウムイオン電池をＢ−Ｂ‘方向からみた横断面図である。１１は基材層、１２は金属箔等からなるバリア層、１３はヒートシール層であるＰＰ層を表す。矢印ｙ方向において、外装体周縁部５ａでは外装体内部と外装体外部は金属箔等を介さずＰＰ層のみで繋がっている。したがって内部のガスはバリア層１２の内側に設けられたヒートシール層１３の層間をｙ方向に透過し外部へ放出される。しかし、このＰＰ層の厚みは、外部からの水蒸気の浸入を防ぐため非常に薄く外装体周縁部５ａにおけるガス排出量は非常に少ない。 Further, when the innermost layer of the outer package 5 is composed of a PP layer, the gas generated inside the outer package is also released from the outer periphery 5a (see FIG. 1A) in addition to the gas permeable portion 7. FIG. 4 is a cross-sectional view of the lithium ion battery shown in FIG. 1A viewed from the B-B ′ direction. Reference numeral 11 denotes a base material layer, 12 denotes a barrier layer made of a metal foil or the like, and 13 denotes a PP layer which is a heat seal layer. In the direction of the arrow y, the exterior body periphery 5a connects the interior of the exterior body and the exterior of the exterior body only with the PP layer without a metal foil or the like. Therefore, the internal gas passes through the interlayer of the heat seal layer 13 provided inside the barrier layer 12 in the y direction and is released to the outside. However, the thickness of the PP layer is very thin in order to prevent the entry of water vapor from the outside, and the amount of gas discharged from the outer periphery 5a is very small.
したがって、外装体内部で発生するガスが微量である場合、上記外装体周縁部５ａのＰＰ層の層間よりガスが放出され外装体５の内圧が上昇することはないが、ガス発生量が外装体周縁部５ａのＰＰ層の層間より放出されるガス放出量を上回る場合、内圧が上昇し弁部９の凝集破壊につながる。また、弁部９の凝集破壊後、ガス透過部７と外装体周縁部５ａのＰＰ層の層間から放出されるガス放出量の総量がガス発生量を上回らなければ内圧は上昇し続け、ガス透過部７が破裂し電解質がガス透過部７から噴出することになる。 Therefore, when a small amount of gas is generated inside the exterior body, the gas is not released from the PP layer of the exterior body peripheral edge 5a and the internal pressure of the exterior body 5 does not increase. When it exceeds the amount of gas released from the interlayer of the PP layer of the peripheral edge 5a, the internal pressure rises, leading to cohesive failure of the valve part 9. Further, after the cohesive failure of the valve portion 9, if the total amount of gas released from the interlayer of the gas permeation portion 7 and the PP layer of the outer periphery 5a does not exceed the gas generation amount, the internal pressure continues to rise, The part 7 is ruptured and the electrolyte is ejected from the gas permeable part 7.
したがって、ガス透過部７におけるガス放出量を十分確保するため、ＰＰ単層フィルム１０を蛇腹状に折り込み一定の表面積を確保する必要がある。なお、外装体周縁部５ａのＰＰ層の層間におけるガス放出量は、外装体周縁部５ａの長さにＰＰ層の厚さを乗じた表面積に比例する。これにより、外装体内部におけるガス発生量とこの外装体周縁部５ａの表面積から、ガス透過部７におけるＰＰ単層フィルム１０の必要表面積を計算し予測することができる。 Therefore, in order to ensure a sufficient amount of gas release from the gas permeable portion 7, it is necessary to fold the PP single layer film 10 into a bellows shape to ensure a certain surface area. The amount of gas released between the layers of the PP layer at the outer periphery 5a is proportional to the surface area obtained by multiplying the length of the outer periphery 5a by the thickness of the PP layer. Thereby, the required surface area of the PP single layer film 10 in the gas permeable part 7 can be calculated and predicted from the amount of gas generated inside the exterior body and the surface area of the exterior body periphery 5a.
次に検知タブ１５の構造について説明する。図５（ｂ）は検知タブ１５を拡大して示した概略平面図である。検知タブ１５は導電性金属１７が平行に近接するように成形され、その両端が検知装置１６内の電源と接続されている。また、導電性金属１７には所定の電流が流されている。ここで、電解質が導電性金属１８に接触すると、その部分の抵抗値が変化し導電性金属１７にかかる電圧も変化する。この電圧の変化を検知装置１６が検知し、電解質の漏洩と判断する。なお、本発明に係る検知タブ１５は上記構造に限定されず、電解質を検知タブ１５が検知しその情報を検知装置１６へ送信できるものであればよい。 Next, the structure of the detection tab 15 will be described. FIG. 5B is an enlarged schematic plan view showing the detection tab 15. The detection tab 15 is formed so that the conductive metal 17 is close in parallel, and both ends thereof are connected to a power source in the detection device 16. A predetermined current is passed through the conductive metal 17. Here, when the electrolyte contacts the conductive metal 18, the resistance value of that portion changes and the voltage applied to the conductive metal 17 also changes. The change of the voltage is detected by the detection device 16 and it is determined that the electrolyte leaks. The detection tab 15 according to the present invention is not limited to the above-described structure, and may be any as long as the detection tab 15 can detect the electrolyte and transmit the information to the detection device 16.
なお、本発明において検知タブ１５は電解質の漏洩を検知するために用いているが、本発明に係る検知タブ１５と同様の方法で外装体外部からガス透過部７を介して浸入した水蒸気を検知する検知タブを設け、水蒸気の浸入を検知することも可能である。また、これら２つの検知タブ設けることにより、外装体５の破裂だけでなく外装体５のデラミネーション（剥離）の発生を未然に防止することができると解する。 In the present invention, the detection tab 15 is used to detect leakage of the electrolyte, but water vapor that has entered from the exterior of the exterior body through the gas permeable portion 7 is detected in the same manner as the detection tab 15 according to the present invention. It is also possible to provide a detection tab that detects water vapor intrusion. Further, it is understood that by providing these two detection tabs, not only the rupture of the outer package 5 but also the occurrence of delamination (peeling) of the outer package 5 can be prevented.
次に、ガス透過部７に蛇腹状に折り込んだＰＰ単層フィルム１０を用いる場合の外装体５へのシール方法について説明する。リチウムイオン電池は袋状に形成された外装体５の中にリチウムイオン電池本体を入れて密封する。このとき、外装体５開口部において、予め蛇腹状に形成したＰＰ単層フィルム１０とＰＰとＰＥのブレンド樹脂のフィルム片、を所定の位置で外装体５に挟持させヒートシールすることでガス透過部７と弁部９が形成される。また、検知タブ１５の端部１５ａをＰＰ単層フィルム１０とブレンド樹脂のフィルム片の間に配し、ＰＰ単層フィルム１０の下端１０ｂと外装体５で検知タブ１５を挟持してヒートシールすれば、安全弁６と検知タブ１５が一体となった状態で構成される。 Next, the sealing method to the exterior body 5 in the case of using the PP single layer film 10 folded in a bellows shape in the gas permeable portion 7 will be described. The lithium ion battery is sealed by putting the lithium ion battery main body in a package 5 formed in a bag shape. At this time, gas permeation is performed by sandwiching the PP single-layer film 10 formed in advance in a bellows shape and a PP / PE blend resin film piece at a predetermined position in the exterior body 5 and heat-sealing at the opening of the exterior body 5. Part 7 and valve part 9 are formed. Further, the end portion 15a of the detection tab 15 is disposed between the PP single layer film 10 and the blend resin film piece, and the detection tab 15 is sandwiched between the lower end 10b of the PP single layer film 10 and the exterior body 5 to be heat sealed. For example, the safety valve 6 and the detection tab 15 are integrated.
なお、図１（ｂ）を示して前述したようにガス透過部７と弁部９の間はヒートシールせず、ガス通気路８を形成する必要がある。 Note that, as described above with reference to FIG. 1B, it is necessary to form the gas ventilation path 8 without heat sealing between the gas permeable part 7 and the valve part 9.
しかし、蛇腹状に形成したＰＰ単層フィルム１０を外装体５で挟持して単にヒートシールしただけでは、ＰＰ単層フィルム１０自体が熱融着性を有するため蛇腹状の山折り部と谷折り部が一体となって外装体５最内層のＰＰ層及び検知タブ１５と融着する。また、ＰＰ単層フィルム１０の端部１０ａまたは１０ｂにおいて、外装体５の上面と下面が検知タブ１５を介して接着した場合も蛇腹状にガス透過部７を形成することができない。 However, if the PP single-layer film 10 formed in a bellows shape is sandwiched between the exterior bodies 5 and merely heat-sealed, the PP single-layer film 10 itself has a heat-sealing property, so that the bellows-shaped mountain folds and valley folds are formed. The parts are integrated and fused with the PP layer and the detection tab 15 in the innermost layer of the outer package 5. Further, even when the upper surface and the lower surface of the outer package 5 are bonded via the detection tab 15 at the end portion 10a or 10b of the PP single layer film 10, the gas permeable portion 7 cannot be formed in a bellows shape.
したがって、ＰＰ単層フィルム１０が蛇腹状に形成された状態で外装体内部を密封シールするにはＰＰ単層フィルム１０の上端部１０ａを外装体５上面に下端部１０ｂを外装体５下面にシールする必要がある。そのためには、図３（ｂ）に示すように上端部１０ａの下面及び下端部１０ｂの上面に融着防止フィルム１４を介して上端部１０ａと下端部１０ｂとシールする部分を加圧及び加熱すればよい。 Therefore, in order to hermetically seal the inside of the exterior body with the PP single layer film 10 formed in a bellows shape, the upper end portion 10a of the PP single layer film 10 is sealed on the upper surface of the exterior body 5 and the lower end portion 10b is sealed on the lower surface of the exterior body 5. There is a need to. For this purpose, as shown in FIG. 3B, the upper and lower end portions of the upper end 10a and the lower end 10b are pressed and heated on the lower surface and the upper surface of the lower end 10b via the anti-fusing film 14, respectively. That's fine.
なお、本発明は上述した各実施形態に限定されるものではなく、種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本発明の技術的範囲に含まれる。 The present invention is not limited to the above-described embodiments, and various modifications are possible. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the present invention. Included in the technical scope.
本発明は、エネルギー貯蔵用や電気自動車用の電源として好適な、耐久性、安全性の高いリチウムイオン電池に関するものである。 The present invention relates to a durable and safe lithium ion battery suitable as a power source for energy storage and electric vehicles.
１ リチウムイオン電池
２ リチウムイオン電池本体
３ セル（蓄電部）
４ タブ
４ａ タブ材
４ｂ リチウムイオン電池金属端子部密封用接着性フィルム
５ 外装体
５ａ 外装体周縁部
７ ガス透過部
８ ガス通気路
９ 弁部
１０ ＰＰ単層フィルム
１０ａ 上端部
１０ｂ 下端部
１１ 基材層
１２ バリア層
１３ 最内層（ヒートシール層）
１４ 融着防止フィルム
１５ 検知タブ
１５ａ 端部
１６ 検知器
１７ 導電性金属
DESCRIPTION OF SYMBOLS 1 Lithium ion battery 2 Lithium ion battery main body 3 Cell (electric storage part)
4 Tab 4a Tab Material 4b Lithium Ion Battery Metal Terminal Sealing Adhesive Film 5 Outer Body 5a Outer Body Perimeter 7 Gas Permeation Part 8 Gas Vent 9 Valve Part 10 PP Single Layer Film 10a Upper End Part 10b Lower End Part 11 Base Material Layer 12 Barrier layer 13 Innermost layer (heat seal layer)
14 Fusing Prevention Film 15 Detection Tab 15a End 16 Detector 17 Conductive Metal
Claims (6)
前記外装体の周縁部の一部に外装体内部で発生したガスを外装体外部に逃すための安全弁を設け、
該安全弁が外装体内部のガス圧が所定値を超えたとき開く弁部と、
ガスのみを透過するガス透過部と、
前記弁部から前記ガス透過部へガスを導くガス通気路とで構成され、
前記弁部と前記ガス透過部がそれぞれ前記ガス通気路を介して外装体内側と外装体外側に配され、
前記ガス透過部は前記外装体に挟持されたガス透過性を有する高分子フィルムが前記シール層とヒートシールされて形成され、
前記弁部は前記シール層とヒートシール可能な樹脂を前記外層体の前記シール層間に挟持させて当接する前記シール層とヒートシールされて形成されるとともに前記シール層間に挟持された前記樹脂と前記シール層との接着強度が前記シール層同士の接着強度よりも低く、
前記ガス通気路に電解質の漏れを検知するための検知タブを設けたことを特徴とするリチウムイオン電池。 A laminate including a positive electrode, a negative electrode, a cell including an electrolyte filled between the positive electrode and the negative electrode, and a lithium ion battery body having a tab connected to each of the positive electrode and the negative electrode, and a seal layer as an innermost layer In a lithium ion battery that is hermetically sealed by heat-sealing the peripheral portion of the exterior body while projecting the tab to the exterior of the exterior body ,
A safety valve for letting gas generated inside the exterior body escape to the outside of the exterior body is provided in a part of the peripheral edge of the exterior body,
A valve part that the safety valve opens when the gas pressure inside the exterior body exceeds a predetermined value;
A gas permeation section that allows only gas to pass through;
A gas ventilation path that guides gas from the valve part to the gas permeation part,
The valve part and the gas permeable part are respectively arranged on the outer side of the outer body and the outer side of the outer body through the gas ventilation path,
The gas permeable portion is formed by heat-sealing a polymer film having gas permeability sandwiched between the exterior bodies and the seal layer,
The valve portion is formed by heat-sealing with the seal layer that is in contact with the seal layer and the heat-sealable resin sandwiched between the seal layers of the outer layer body, and the resin sandwiched between the seal layers and the resin The adhesive strength with the sealing layer is lower than the adhesive strength between the sealing layers,
A lithium ion battery comprising a detection tab for detecting leakage of an electrolyte in the gas ventilation path.
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| JP2006087326A JP5261884B2 (en) | 2006-03-28 | 2006-03-28 | Lithium ion battery |
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| JP2006087326A JP5261884B2 (en) | 2006-03-28 | 2006-03-28 | Lithium ion battery |
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| JP5261884B2 true JP5261884B2 (en) | 2013-08-14 |
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Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP5261908B2 (en) * | 2006-09-20 | 2013-08-14 | 大日本印刷株式会社 | Flat electrochemical cell |
| DE102011016527A1 (en) * | 2011-04-08 | 2012-10-11 | Daimler Ag | Apparatus and method for leak detection of an electrochemical energy storage device |
| JP5840923B2 (en) | 2011-11-07 | 2016-01-06 | 昭和電工パッケージング株式会社 | Battery exterior body, method for producing battery exterior body, and lithium secondary battery |
| JP6152260B2 (en) | 2012-11-01 | 2017-06-21 | 昭和電工パッケージング株式会社 | Battery exterior material and battery |
| JP5969368B2 (en) | 2012-11-30 | 2016-08-17 | 昭和電工パッケージング株式会社 | Exterior body for electrochemical element |
| DE102013219223A1 (en) | 2013-09-25 | 2015-03-26 | Robert Bosch Gmbh | Degassing valve for battery cells |
| KR102177819B1 (en) * | 2016-02-11 | 2020-11-11 | 주식회사 엘지화학 | Method and apparatus for manufacturing of prismatic secondary battery |
| CN109425469A (en) * | 2017-08-21 | 2019-03-05 | 宁德时代新能源科技股份有限公司 | Battery module and method for detecting air tightness of battery module |
| JP7180407B2 (en) | 2019-01-24 | 2022-11-30 | Tdk株式会社 | battery pack |
| CN112787029B (en) * | 2019-11-01 | 2024-03-22 | 奥迪股份公司 | Battery system for vehicle and vehicle |
| KR20210155280A (en) * | 2020-06-15 | 2021-12-22 | 주식회사 엘지에너지솔루션 | Secondary battery |
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| JP4604441B2 (en) * | 2002-07-18 | 2011-01-05 | 日本電気株式会社 | Film-clad battery and manufacturing method thereof |
| JP2005197279A (en) * | 2003-12-26 | 2005-07-21 | Toyota Motor Corp | Electric storage element and electric storage module using the same |
| JP3884039B2 (en) * | 2004-10-29 | 2007-02-21 | 株式会社パワーシステム | Gas vent valve |
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