JP2016189302A - Battery and insulation film - Google Patents

Battery and insulation film Download PDF

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JP2016189302A
JP2016189302A JP2015069597A JP2015069597A JP2016189302A JP 2016189302 A JP2016189302 A JP 2016189302A JP 2015069597 A JP2015069597 A JP 2015069597A JP 2015069597 A JP2015069597 A JP 2015069597A JP 2016189302 A JP2016189302 A JP 2016189302A
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battery
insulating film
battery case
electrode body
insulating
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JP6219873B2 (en
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圭一郎 小林
Keiichiro Kobayashi
圭一郎 小林
洋一 松浦
Yoichi Matsuura
洋一 松浦
山田　聡
Satoshi Yamada
聡 山田
佳孝 深貝
Yoshitaka Fukagai
佳孝 深貝
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Toray Advanced Film Co Ltd
Toyota Motor Corp
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Toray Advanced Film Co Ltd
Toyota Motor Corp
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/10—Homopolymers or copolymers of propene
    • C08L23/12—Polypropene
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/131—Primary casings, jackets or wrappings of a single cell or a single battery characterised by physical properties, e.g. gas-permeability or size
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/102—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure
    • H01M50/103—Primary casings, jackets or wrappings of a single cell or a single battery characterised by their shape or physical structure prismatic or rectangular
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
    • H01M50/117—Inorganic material
    • H01M50/119—Metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
    • H01M50/121—Organic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings, jackets or wrappings of a single cell or a single battery
    • H01M50/116—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material
    • H01M50/124—Primary casings, jackets or wrappings of a single cell or a single battery characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

PROBLEM TO BE SOLVED: To provide a battery that can suppress occurrence of crack or breaking in an insulation film of an insulation member interposed between a battery case and an electrode body, and has high reliability, and an insulation film used for the same.SOLUTION: A battery 1 comprises a metallic battery case 10, an electrode body 20 housed in the battery case, and an insulating member 30 which is formed of an insulating film 31 and interposed between the battery case 10 and the electrode body 20 to insulate both the battery case and the electrode body from each other. The insulating film 31 contains polypropylene-based resin as a main component, and cold xylene-soluble content of 16 wt% or less, has a yield point strength of 2.5 to 7.4 N/mm under an atmosphere of 60°C and contains no organic lubricant.SELECTED DRAWING: Figure 1

Description

本発明は、金属製の電池ケースと、これに収容された電極体と、絶縁フィルムからなり、電池ケースと電極体との間に介在して両者を絶縁する絶縁部材とを備える電池、及び、この電池に用いる絶縁フィルムに関する。   The present invention is a battery comprising a metal battery case, an electrode body accommodated therein, an insulating film, and an insulating member interposed between the battery case and the electrode body to insulate both, and The present invention relates to an insulating film used for this battery.

従来より、金属製の電池ケース内に電極体を収容する電池において、電池ケースと電極体との間を電気的に絶縁するために、両者の間に絶縁フィルムからなる絶縁部材を介在させることが知られている。例えば特許文献１には、電極体を、絶縁フィルムを袋状にした絶縁部材内に収め、更にこれらを電池ケース内に収容することで、電池ケースと電極体との間を絶縁部材で絶縁した電池が開示されている（特許文献１の特許請求の範囲、図２、図８等を参照）。   Conventionally, in a battery in which an electrode body is housed in a metal battery case, an insulating member made of an insulating film is interposed between the battery case and the electrode body in order to electrically insulate between the battery case and the electrode body. Are known. For example, in Patent Document 1, the electrode body is housed in an insulating member made of an insulating film in a bag shape, and further housed in the battery case, whereby the battery case and the electrode body are insulated by the insulating member. A battery is disclosed (refer to the claims of Patent Document 1, FIG. 2, FIG. 8, etc.).

特開２０１０−２８７４５６号公報JP 2010-287456 A

しかしながら、電池の使用条件によっては、特に車両に搭載される車載用電池は、低温から高温まで厳しい温度条件下で使用され得る。また、車両が悪路を走行した際などに、電池に大きな衝撃が伝わることがある。このように電池が厳しい温度条件下で使用されたり、電池が大きな衝撃を受けると、電池ケースと電極体との間に介在する絶縁部材の絶縁フィルムに亀裂や破れが生じて、電池ケースと電極体との間の絶縁性が損なわれるおそれがある。   However, depending on the use conditions of the battery, the vehicle-mounted battery mounted on the vehicle can be used under severe temperature conditions from low temperature to high temperature. Further, when the vehicle travels on a rough road, a large impact may be transmitted to the battery. Thus, when the battery is used under severe temperature conditions or when the battery is subjected to a large impact, the insulating film of the insulating member interposed between the battery case and the electrode body is cracked or torn, and the battery case and the electrode Insulation between the body and the body may be impaired.

具体的には、電池の使用温度条件を考慮して、後に詳述するように、例えば電池温度を−３０〜５０℃の範囲で繰り返し変動させる熱衝撃試験（以下、単に「熱衝撃試験」とも言う）を行うと、絶縁フィルムに破断が生じる場合があることが判った。
また、電池を搭載した車両は、低温環境下で悪路を走行することがある。そこで、後に詳述するように、電池が−３０℃の低温状態で、車両が突起を乗り越えるときなどに電池が受ける衝撃を考慮した低温衝撃試験（以下、単に「低温衝撃試験」とも言う）を行うと、絶縁フィルムに、特に絶縁フィルムの折り曲げ部分に、微小な亀裂（クレーズ）が発生し、更にはその亀裂に起因して破れが生じる場合もあることが判った。 Specifically, in consideration of the battery operating temperature conditions, as will be described in detail later, for example, a thermal shock test (hereinafter simply referred to as “thermal shock test”) in which the battery temperature is repeatedly varied in the range of −30 to 50 ° C. It was found that the insulating film sometimes breaks.
A vehicle equipped with a battery may travel on a rough road in a low temperature environment. Therefore, as will be described in detail later, a low temperature impact test (hereinafter also simply referred to as “low temperature impact test”) taking into consideration the impact that the battery receives when the vehicle gets over the protrusions in a low temperature state of −30 ° C. When it did, it turned out that a micro crack (craze) generate | occur | produces in the insulating film, especially in the bending part of an insulating film, and also a tear may arise due to the crack.

本発明は、かかる現状に鑑みてなされたものであって、電池ケースと電極体との間に介在させる絶縁部材の絶縁フィルムに亀裂や破れが生じ難く、信頼性の高い電池、及び、この電池に用いる絶縁フィルムを提供することを目的とする。   The present invention has been made in view of the current situation, and the insulating film of the insulating member interposed between the battery case and the electrode body is hardly cracked or torn, and the battery having high reliability and the battery It aims at providing the insulating film used for.

上記課題を解決するための本発明の一態様は、金属製の電池ケースと、上記電池ケース内に収容された電極体と、絶縁フィルムからなり、上記電池ケースと上記電極体との間に介在して両者を絶縁する絶縁部材と、を備える電池であって、上記絶縁フィルムは、ポリプロピレン系樹脂を主成分とし、冷キシレン可溶分が１６ｗｔ％以下であり、かつ、６０℃雰囲気下での降伏点強力が２．５〜７．４Ｎ／１０ｍｍである電池である。   One aspect of the present invention for solving the above problems includes a metal battery case, an electrode body accommodated in the battery case, and an insulating film, and is interposed between the battery case and the electrode body. And an insulating member that insulates the two, wherein the insulating film is mainly composed of a polypropylene resin, has a soluble content of cold xylene of 16 wt% or less, and in an atmosphere at 60 ° C. A battery having a yield point strength of 2.5 to 7.4 N / 10 mm.

この電池では、上述の絶縁フィルムからなる絶縁部材を備えるので、後述する「熱衝撃試験」や「低温衝撃試験」を行っても、絶縁フィルムに亀裂や破れが生じるのを防止できる。従って、この電池は、電池ケースと電極体との間に介在させる絶縁部材の絶縁フィルムに亀裂や破れが生じ難く、信頼性が高い。   Since this battery includes an insulating member made of the above-described insulating film, it is possible to prevent the insulating film from being cracked or torn even if a “thermal shock test” or “low temperature shock test” described later is performed. Therefore, this battery has high reliability because the insulating film of the insulating member interposed between the battery case and the electrode body is hardly cracked or torn.

なお、「熱衝撃試験」は、例えば、エスペック株式会社製の液槽冷熱衝撃装置ＴＳＢシリーズや同社製の冷熱衝撃装置ＴＳＡシリーズを用いて行う。具体的には、電池の使用温度条件を考慮して、電池温度を−３０〜５０℃の範囲で繰り返し冷却、加熱する。まず、電池温度を５０℃にして３分間維持する。その後、電池温度を５０℃から−３０℃まで降温速度３℃／ｍｉｎで冷却して、−３０℃を３分間維持する。その後、電池温度を−３０℃から５０℃まで昇温速度３℃／ｍｉｎで加熱して、５０℃を３分間維持する。この冷却・加熱を１サイクルとして、これを１０００サイクル行う。   The “thermal shock test” is performed using, for example, a liquid bath cold thermal shock device TSB series manufactured by Espec Co., Ltd. or a cold thermal shock device TSA series manufactured by the same company. Specifically, the battery temperature is repeatedly cooled and heated in the range of −30 to 50 ° C. in consideration of the use temperature condition of the battery. First, the battery temperature is set to 50 ° C. and maintained for 3 minutes. Thereafter, the battery temperature is cooled from 50 ° C. to −30 ° C. at a temperature lowering rate of 3 ° C./min, and −30 ° C. is maintained for 3 minutes. Thereafter, the battery temperature is heated from −30 ° C. to 50 ° C. at a rate of temperature increase of 3 ° C./min and maintained at 50 ° C. for 3 minutes. This cooling / heating is performed as one cycle, and 1000 cycles are performed.

「低温衝撃試験」は、例えば、ＩＭＶ株式会社製の振動試験装置ｉ２４０／ＳＡ３Ｍ／Ｃを用いて行う。具体的には、−３０℃の環境下で、電池に１０Ｇ以上の正弦半波の衝撃を所定回数与える。   The “low temperature impact test” is performed using, for example, a vibration test apparatus i240 / SA3M / C manufactured by IMV Corporation. Specifically, a sine half-wave impact of 10 G or more is given a predetermined number of times in an environment of −30 ° C.

「絶縁フィルム」が「ポリプロピレン系樹脂を主成分とする」とは、絶縁フィルムを構成する材質の中で、ポリプロピレン系樹脂の割合が５０ｗｔ％を越えていることを言う。
「ポリプロピレン系樹脂」としては、例えば、プロピレンが単独重合したものや、プロピレンにエチレンやブテンが共重合したランダムコポリマー、プロピレン重合時にエチレン・プロピレンゴム等のエチレン系エラストマーを重合ブレンドしたブロックコポリマーなどが挙げられる。 “Insulating film” means that “the main component is polypropylene resin” means that the proportion of the polypropylene resin exceeds 50 wt% in the material constituting the insulating film.
Examples of the “polypropylene resin” include those obtained by homopolymerizing propylene, random copolymers obtained by copolymerizing propylene with ethylene or butene, and block copolymers obtained by polymerizing and blending ethylene elastomer such as ethylene / propylene rubber during propylene polymerization. Can be mentioned.

また、「絶縁フィルム」としては、ポリプロピレン系樹脂のほかに、エチレン−α−オレフィン共重合体を含ませたフィルム、具体的には、低結晶性エチレン−α−オレフィン共重合体及び非結晶性エチレン−α−オレフィン共重合体の少なくともいずれかを含ませたフィルムを用いることができる。この低結晶性エチレン−α−オレフィン共重合体及び非結晶性エチレン−α−オレフィン共重合体は、熱可塑性エラストマーであることが好ましい。エチレン−α−オレフィン共重合体の熱可塑性エラストマーを含ませることで、ポリプロピレン系樹脂の低温衝撃性を改良できる。具体的には、低結晶性エチレン−α−オレフィン共重合体の熱可塑性エラストマーとして、エチレン・ブテンゴム（ＥＢＲ）、非結晶性エチレン−α−オレフィン共重合体の熱可塑性エラストマーとして、エチレン・プロピレンゴム（ＥＰＲ）などが挙げられる。   The “insulating film” includes a film containing an ethylene-α-olefin copolymer in addition to a polypropylene resin, specifically, a low crystalline ethylene-α-olefin copolymer and an amorphous material. A film containing at least one of an ethylene-α-olefin copolymer can be used. The low crystalline ethylene-α-olefin copolymer and the amorphous ethylene-α-olefin copolymer are preferably thermoplastic elastomers. By including the thermoplastic elastomer of the ethylene-α-olefin copolymer, the low temperature impact property of the polypropylene resin can be improved. Specifically, as a thermoplastic elastomer of a low crystalline ethylene-α-olefin copolymer, ethylene / butene rubber (EBR), as a thermoplastic elastomer of an amorphous ethylene-α-olefin copolymer, ethylene / propylene rubber (EPR).

絶縁フィルムの「冷キシレン可溶分」は、２０℃キシレン可溶成分量（ＣＸＳ）（ｗｔ％）であり、以下の手法により求める。即ち、絶縁フィルムの試料１ｇを沸騰キシレン１００ｍｌに完全溶解させた後、２０℃に降温し、４時間放置する。その後、これを析出物と溶液とに濾別し、濾液を乾固して減圧下、７０℃で乾燥し、残存物を得る。得られた残存物の質量を測定して、試料１ｇに対する割合を求めて、２０℃キシレン可溶成分量（ｗｔ％）とする。   The “cold xylene soluble content” of the insulating film is 20 ° C. xylene soluble component amount (CXS) (wt%), and is determined by the following method. That is, 1 g of a sample of an insulating film is completely dissolved in 100 ml of boiling xylene, then cooled to 20 ° C. and left for 4 hours. Thereafter, this is separated into a precipitate and a solution, and the filtrate is dried and dried at 70 ° C. under reduced pressure to obtain a residue. The mass of the obtained residue is measured, and the ratio with respect to 1 g of the sample is obtained to obtain the 20 ° C. xylene-soluble component amount (wt%).

「６０℃雰囲気下での降伏点強力（Ｎ／１０ｍｍ）」は、以下の手法により求める。具体的には、株式会社エー・アンド・デイ社製のテンシロンＲＴＧ−１２１０に、三田産業社製のテンシロン用高低温度恒温槽ＴＬＦ−Ｒ３Ｔ−Ｆ−Ｇ−Ａを取り付けた引っ張り試験装置を用いる。絶縁フィルムを製膜流れ方向に１００ｍｍ、幅方向に１０ｍｍの大きさに切断したものを、チャック間５０ｍｍで挟み、測定雰囲気温度６０℃、引っ張り速度３００ｍｍ／分で引っ張って、引っ張り強力を測定する。そして、この測定により得られる引っ張り強力−変異曲線（Ｓ−Ｓカーブ）について、引っ張り強力の最初のピークにおける引っ張り強力を降伏点強力（Ｎ／１０ｍｍ）とする。   “Yield point strength at 60 ° C. atmosphere (N / 10 mm)” is determined by the following method. Specifically, a tensile test apparatus is used in which a high and low temperature thermostat TLF-R3T-FGA for Tensilon is attached to Tensilon RTG-1210 manufactured by A & D Co., Ltd. An insulating film cut to a size of 100 mm in the film forming flow direction and 10 mm in the width direction is sandwiched between chucks at 50 mm, and pulled at a measurement atmosphere temperature of 60 ° C. and a pulling speed of 300 mm / min to measure the tensile strength. And about the tensile strength-mutation curve (SS curve) obtained by this measurement, let the tensile strength in the first peak of tensile strength be a yield point strength (N / 10mm).

「電池ケース」の形態は、特に限定されず、例えば、角型の電池ケースや、円筒型の電池ケースなどが挙げられる。
また、「電極体」の形態は、特に限定されず、例えば、各々帯状をなす正極板及び負極板をセパレータを介して捲回してなる扁平状や円筒状の捲回型の電極体や、矩形状等をなす正極板及び負極板をセパレータを介して複数積層した積層型の電極体などが挙げられる。 The form of the “battery case” is not particularly limited, and examples thereof include a rectangular battery case and a cylindrical battery case.
The form of the “electrode body” is not particularly limited. For example, a flat or cylindrical wound electrode body formed by winding a positive electrode plate and a negative electrode plate each having a band shape through a separator, Examples include a stacked electrode body in which a plurality of positive and negative electrode plates having a shape or the like are stacked with a separator interposed therebetween.

更に、上記の電池であって、前記絶縁フィルムは、前記ポリプロピレン系樹脂とは別に、エチレン−α−オレフィン共重合体の熱可塑性エラストマーを含有する電池とすると良い。この電池では、絶縁部材の絶縁フィルムに亀裂や破れが更に生じ難く、更に信頼性が高い。   Further, in the battery described above, the insulating film may be a battery containing a thermoplastic elastomer of an ethylene-α-olefin copolymer separately from the polypropylene resin. In this battery, the insulating film of the insulating member is not easily cracked or torn, and the reliability is higher.

更に、上記の電池であって、前記絶縁フィルムは、未延伸フィルムであり、前記絶縁部材は、上記絶縁フィルムを溶着して形成してなる電池とすると良い。未延伸フィルムを用いることで、溶着により容易に絶縁部材を形成できるので、信頼性の高い電池とすることができる。   Furthermore, in the above battery, the insulating film is an unstretched film, and the insulating member is preferably a battery formed by welding the insulating film. By using an unstretched film, an insulating member can be easily formed by welding, so that a highly reliable battery can be obtained.

更に、上記のいずれかに記載の電池であって、前記絶縁部材は、前記電極体を包囲する袋状絶縁部材である電池とすると良い。この電池では、絶縁部材が袋状絶縁部材であるので、袋状絶縁部材により電極体を確実に包囲して、電極体と電池ケースとの間を確実に絶縁できる。   Furthermore, in the battery according to any one of the above, the insulating member may be a battery that is a bag-like insulating member surrounding the electrode body. In this battery, since the insulating member is a bag-like insulating member, the electrode body can be reliably surrounded by the bag-like insulating member, and the electrode body and the battery case can be reliably insulated.

また、他の態様は、金属製の電池ケースと、上記電池ケース内に収容された電極体と、絶縁フィルムからなり、上記電池ケースと上記電極体との間に介在して両者を絶縁する絶縁部材と、を備える電池に用いられる上記絶縁フィルムであって、ポリプロピレン系樹脂を主成分とし、冷キシレン可溶分が１６ｗｔ％以下であり、かつ、６０℃雰囲気下での降伏点強力が２．５〜７．４Ｎ／１０ｍｍである絶縁フィルムである。   In another aspect, the battery comprises a metal battery case, an electrode body accommodated in the battery case, and an insulating film, and is interposed between the battery case and the electrode body to insulate the two. And an insulating film for use in a battery comprising a member, having a polypropylene-based resin as a main component, a cold xylene soluble content of 16 wt% or less, and a yield point strength in a 60 ° C. atmosphere of 2. It is an insulating film which is 5-7.4N / 10mm.

この絶縁フィルムを用いて絶縁部材を形成し、更にこれを用いて電池を製造すれば、前述のように、絶縁フィルムに亀裂や破れが更に生じ難く、更に信頼性が高い電池とすることができる。   If an insulating member is formed using this insulating film, and a battery is further manufactured using the insulating member, as described above, the insulating film is not easily cracked or torn, and a battery with higher reliability can be obtained. .

更に、上記の絶縁フィルムであって、前記ポリプロピレン系樹脂とは別に、エチレン−α−オレフィン共重合体の熱可塑性エラストマーを含有する絶縁フィルムとすると良い。この絶縁フィルムを用いて絶縁部材を形成し、更にこれを用いて電池を製造すれば、絶縁フィルムに亀裂や破れが更に生じ難く、更に信頼性が高い電池とすることができる。   Furthermore, the insulating film is preferably an insulating film containing a thermoplastic elastomer of an ethylene-α-olefin copolymer separately from the polypropylene resin. If an insulating member is formed using this insulating film, and a battery is manufactured using the insulating member, the insulating film is less likely to be cracked or broken, and a battery with higher reliability can be obtained.

更に、上記の絶縁フィルムであって、前記電池の前記絶縁部材は、上記絶縁フィルムを溶着して形成してなり、上記絶縁フィルムは、未延伸フィルムである絶縁フィルムとすると良い。未延伸フィルムを用いることで、溶着により容易に絶縁部材を形成でき、更にこれを用いて電池を製造すれば、信頼性の高い電池とすることができる。   Furthermore, it is said insulating film, Comprising: The said insulating member of the said battery is formed by welding the said insulating film, and it is good for the said insulating film to be an insulating film which is an unstretched film. By using an unstretched film, an insulating member can be easily formed by welding, and if a battery is manufactured using this, a highly reliable battery can be obtained.

実施形態に係るリチウムイオン二次電池の縦断面図である。It is a longitudinal cross-sectional view of the lithium ion secondary battery which concerns on embodiment. 実施形態に係る袋状絶縁部材の斜視図である。It is a perspective view of the bag-shaped insulating member concerning an embodiment.

以下、本発明の実施の形態を、図面を参照しつつ説明する。図１に、本実施形態に係るリチウムイオン二次電池（非水電解質二次電池）１（以下、単に「電池１」とも言う）を示す。また、図２に、本実施形態に係る袋状絶縁部材（絶縁部材）３０を示す。なお、本明細書では、図１における上方を電池１の上側ＵＷ、下方を電池１の下側ＤＷとして説明する。
この電池１は、ハイブリッド自動車や電気自動車等の車両などに搭載される角型で密閉型のリチウムイオン二次電池である。この電池１は、電池ケース１０と、この内部に収容された電極体２０と、電池ケース１０と電極体２０との間に配置された袋状絶縁部材３０と、電池ケース１０に支持された正極端子４０及び負極端子４１等から構成されている。また、電池ケース１０内には、非水系の電解液１７が保持されている。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a lithium ion secondary battery (nonaqueous electrolyte secondary battery) 1 (hereinafter also simply referred to as “battery 1”) according to the present embodiment. FIG. 2 shows a bag-like insulating member (insulating member) 30 according to this embodiment. In this specification, the upper side in FIG. 1 is described as the upper side UW of the battery 1 and the lower side is described as the lower side DW of the battery 1.
The battery 1 is a rectangular and sealed lithium ion secondary battery mounted on a vehicle such as a hybrid vehicle or an electric vehicle. The battery 1 includes a battery case 10, an electrode body 20 accommodated therein, a bag-like insulating member 30 disposed between the battery case 10 and the electrode body 20, and a positive electrode supported by the battery case 10. It consists of a terminal 40, a negative electrode terminal 41, and the like. Further, a non-aqueous electrolyte solution 17 is held in the battery case 10.

このうち電池ケース１０は、直方体状で金属（本実施形態ではアルミニウム）からなる。この電池ケース１０は、上側ＵＷのみが開口した直方体箱状のケース本体部材１１と、このケース本体部材１１の開口１１ｈを閉塞する形態で溶接された矩形板状のケース蓋部材１３とから構成される。ケース蓋部材１３には、電池ケース１０の内圧が所定圧力に達した際に破断する安全弁１４が設けられている。また、このケース蓋部材１３には、電池ケース１０の内外を連通する貫通孔（注液孔）１３ｈが形成されている。この貫通孔１３ｈは、リベット１５により気密に封止されている。
また、ケース蓋部材１３には、それぞれ延出端子部材４３とボルト４４により構成される正極端子４０及び負極端子４１が、樹脂からなる絶縁樹脂部材４７を介して固設されている。電池ケース１０内において、正極端子４０は、後述する電極体２０のうち正極板２１の正極集電部２１ｍに接続され、負極端子４１は、電極体２０のうち負極板２５の負極集電部２５ｍに接続されている。 Among these, the battery case 10 has a rectangular parallelepiped shape and is made of metal (in this embodiment, aluminum). The battery case 10 includes a rectangular parallelepiped box-shaped case main body member 11 in which only the upper UW is opened, and a rectangular plate-shaped case cover member 13 which is welded so as to close the opening 11h of the case main body member 11. The The case lid member 13 is provided with a safety valve 14 that is broken when the internal pressure of the battery case 10 reaches a predetermined pressure. In addition, the case lid member 13 is formed with a through hole (a liquid injection hole) 13 h that communicates the inside and outside of the battery case 10. The through hole 13h is hermetically sealed by a rivet 15.
Further, the case lid member 13 is fixedly provided with a positive terminal 40 and a negative terminal 41 each composed of an extended terminal member 43 and a bolt 44 via an insulating resin member 47 made of resin. In the battery case 10, the positive electrode terminal 40 is connected to the positive electrode current collector 21 m of the positive electrode plate 21 in the electrode body 20 to be described later, and the negative electrode terminal 41 is connected to the negative electrode current collector 25 m of the negative electrode plate 25 in the electrode body 20. It is connected to the.

次に、電極体２０について説明する。この電極体２０は、扁平状をなし、後述する袋状絶縁部材３０内に収められた状態で、電池ケース１０内に収容されている。電極体２０は、帯状の正極板２１と帯状の負極板２５とを、帯状のセパレータ２９を介して互いに重ねて捲回し、扁平状に圧縮したものである。
正極板２１は、帯状のアルミニウム箔からなる正極集電箔２２の両主面のうち、幅方向の一部でかつ長手方向に延びる領域上に、正極活物質層２３を帯状に設けてなる。正極活物質層２３には、正極活物質、導電剤及び結着剤が含まれる。また、正極集電箔２２のうち、幅方向の片方の端部は、自身の厚み方向に正極活物質層２３が存在せず、正極集電箔２２が露出した正極集電部２１ｍとなっている。前述の正極端子４０は、この正極集電部２１ｍに接続している。 Next, the electrode body 20 will be described. The electrode body 20 has a flat shape and is accommodated in the battery case 10 in a state of being accommodated in a bag-like insulating member 30 described later. The electrode body 20 is formed by winding a belt-like positive electrode plate 21 and a belt-like negative electrode plate 25 on each other via a belt-like separator 29 and compressing them into a flat shape.
The positive electrode plate 21 is formed by providing a positive electrode active material layer 23 in a band shape on a region extending in a part of the width direction and extending in the longitudinal direction among both main surfaces of a positive electrode current collector foil 22 made of a band-shaped aluminum foil. The positive electrode active material layer 23 includes a positive electrode active material, a conductive agent, and a binder. Also, one end of the positive electrode current collector foil 22 in the width direction is a positive electrode current collector part 21 m where the positive electrode current collector foil 22 is exposed without the positive electrode active material layer 23 in the thickness direction of the positive electrode current collector foil 22. Yes. The positive electrode terminal 40 is connected to the positive electrode current collector 21m.

また、負極板２５は、帯状の銅箔からなる負極集電箔２６の両主面のうち、幅方向の一部でかつ長手方向に延びる領域上に、負極活物質層２７を帯状に設けてなる。負極活物質層２７には、負極活物質、結着剤及び増粘剤が含まれる。また、負極集電箔２６のうち、幅方向の片方の端部は、自身の厚み方向に負極活物質層２７が存在せず、負極集電箔２６が露出した負極集電部２５ｍとなっている。前述の負極端子４１は、この負極集電部２５ｍに接続している。
また、セパレータ２９は、樹脂、具体的にはポリプロピレン（ＰＰ）とポリエチレン（ＰＥ）からなる多孔質膜であり、帯状をなす。 The negative electrode plate 25 has a negative electrode active material layer 27 formed in a band shape on a part of the width direction and extending in the longitudinal direction of both main surfaces of the negative electrode current collector foil 26 made of a strip-shaped copper foil. Become. The negative electrode active material layer 27 includes a negative electrode active material, a binder, and a thickener. Also, one end of the negative electrode current collector foil 26 in the width direction is a negative electrode current collector 25m where the negative electrode active material layer 27 is not present in the thickness direction of the negative electrode current collector foil 26 and the negative electrode current collector foil 26 is exposed. Yes. The negative electrode terminal 41 described above is connected to the negative electrode current collector 25m.
The separator 29 is a porous film made of resin, specifically, polypropylene (PP) and polyethylene (PE), and has a strip shape.

次に、袋状絶縁部材３０について説明する（図２も参照）。この袋状絶縁部材３０は、所定形状に切断した絶縁フィルム３１を折り畳み、絶縁フィルム３１同士を複数箇所で溶着して固定し、上側ＵＷのみに開口部３０ｈを有する袋状に形成したものである。この袋状絶縁部材３０は、電極体２０を包囲した状態で、電池ケース１０内に収容されており、電池ケース１０と電極体２０との間に介在して両者を電気的に絶縁している。   Next, the bag-like insulating member 30 will be described (see also FIG. 2). This bag-like insulating member 30 is formed in a bag shape in which an insulating film 31 cut into a predetermined shape is folded, the insulating films 31 are welded and fixed to each other at a plurality of locations, and an opening 30h is provided only on the upper UW. . The bag-shaped insulating member 30 is housed in the battery case 10 in a state of surrounding the electrode body 20 and is interposed between the battery case 10 and the electrode body 20 to electrically insulate them. .

袋状絶縁部材３０を構成する絶縁フィルム３１は、ポリプロピレン系樹脂を主成分としている。具体的には、プロピレンが単独重合したホモのポリプロピレン樹脂、プロピレンにエチレンやブテンを共重合したランダムコポリマー樹脂、及び、プロピレンにエチレン系エラストマーをブレンドしたブロックコポリマー樹脂を使用している。また、この絶縁フィルム３１は、エチレン−α−オレフィン共重合体の熱可塑性エラストマー、具体的には、非結晶性エチレン−α−オレフィン共重合体の熱可塑性エラストマー、更に具体的には、エチレン・プロピレンゴム（ＥＰＲ）を含有している。
そして、この絶縁フィルム３１は、前述した手法により測定される「冷キシレン可溶分」が１６ｗｔ％以下（本実施形態では８ｗｔ％）である。更に、前述した手法により測定される「６０℃雰囲気下での降伏点強力」が２．５〜７．４Ｎ／１０ｍｍ（本実施形態では４．５Ｎ／１０ｍｍ）である。 The insulating film 31 constituting the bag-like insulating member 30 is mainly composed of polypropylene resin. Specifically, a homopolypropylene resin obtained by homopolymerizing propylene, a random copolymer resin obtained by copolymerizing propylene with ethylene or butene, and a block copolymer resin obtained by blending propylene with an ethylene-based elastomer are used. The insulating film 31 is made of an ethylene-α-olefin copolymer thermoplastic elastomer, specifically, a non-crystalline ethylene-α-olefin copolymer thermoplastic elastomer, more specifically, ethylene Contains propylene rubber (EPR).
The insulating film 31 has a “cold xylene soluble content” measured by the above-described method of 16 wt% or less (8 wt% in this embodiment). Furthermore, the “yield point strength at 60 ° C. atmosphere” measured by the above-described method is 2.5 to 7.4 N / 10 mm (4.5 N / 10 mm in this embodiment).

この絶縁フィルム３１は、ポリプロピレン系樹脂にエチレン−α−オレフィン共重合体の熱可塑性エラストマー（具体的にはエチレン・プロピレンゴム）を配合した樹脂組成物を、樹脂の融点や溶融粘度（通常１〜２０ｇ／１０分）を考慮して溶融し、Ｔダイやリングダイにより押出し冷却することでフィルムに成型する、常法による製造方法で製造する。
押出されたフィルムは延伸してもよいが、絶縁フィルム３１から絶縁部材３０を形成する際の溶着性を良好にするには、延伸しないのが好ましい。本実施形態の絶縁フィルム３１は、Ｔダイにより押出され、冷却ドラムに巻き付けられながら冷却された未延伸フィルムであり、配向の指標である複屈折率が１×１０-2以下である。 This insulating film 31 is made of a resin composition in which a thermoplastic elastomer (specifically, ethylene / propylene rubber) of an ethylene-α-olefin copolymer is blended with a polypropylene resin, and the melting point and melt viscosity (usually 1 to 1) of the resin. 20 g / 10 min) is melted, extruded by a T die or a ring die, and cooled to be formed into a film.
Although the extruded film may be stretched, it is preferably not stretched in order to improve the weldability when forming the insulating member 30 from the insulating film 31. The insulating film 31 of this embodiment is an unstretched film that is extruded by a T-die and cooled while being wound around a cooling drum, and has a birefringence of 1 × 10 −2 or less, which is an index of orientation.

なお、絶縁フィルム３１の厚さは、樹脂組成物の押出し量と引き取り速度で調整することができる。
また、絶縁フィルム３１の冷キシレン可溶分を１６ｗｔ％以下、６０℃雰囲気下での降伏点強力を２．５〜７．４Ｎ／１０ｍｍとするには、用いるポリプロピレン系樹脂の種類や配合量を適宜変更したり、エチレン−α−オレフィン共重合体の熱可塑性エラストマーの種類や配合量を適宜変更すればよい。 In addition, the thickness of the insulating film 31 can be adjusted with the extrusion amount and take-off speed of a resin composition.
Further, in order to set the cold xylene soluble content of the insulating film 31 to 16 wt% or less and the yield point strength at 60 ° C. to 2.5 to 7.4 N / 10 mm, the type and blending amount of the polypropylene resin to be used What is necessary is just to change suitably and to change suitably the kind and compounding quantity of the thermoplastic elastomer of an ethylene-alpha-olefin copolymer.

（実施例及び比較例）
次いで、本発明の効果を検証するために行った試験の結果について説明する。まず、実施例１〜６として、「冷キシレン可溶分」のみが互いに異なる絶縁フィルム３１で形成した袋状絶縁部材３０を用い、それ以外は実施形態の電池１と同様にした６種類の電池を用意した。具体的には、絶縁フィルムの「冷キシレン可溶分」を、２ｗｔ％（実施例１）、４ｗｔ％（実施例２）、８ｗｔ％（実施例３）、９ｗｔ％（実施例４）、１２ｗｔ％（実施例５）、または１５ｗｔ％（実施例６）とした。なお、実施例３の電池は、前述した実施形態の電池１と同じ絶縁フィルム３１を用いている。
一方、比較例１として、「冷キシレン可溶分」が１７ｗｔ％の絶縁フィルムを用い、それ以外は実施形態の電池１と同様にした電池を用意した。 (Examples and Comparative Examples)
Subsequently, the result of the test conducted in order to verify the effect of this invention is demonstrated. First, as Examples 1 to 6, six types of batteries similar to the battery 1 of the embodiment except that a bag-like insulating member 30 formed of insulating films 31 that differ only in “cold xylene solubles” is used. Prepared. Specifically, the “cold xylene soluble content” of the insulating film is 2 wt% (Example 1), 4 wt% (Example 2), 8 wt% (Example 3), 9 wt% (Example 4), 12 wt%. % (Example 5) or 15 wt% (Example 6). In addition, the battery of Example 3 uses the same insulating film 31 as the battery 1 of the embodiment described above.
On the other hand, as Comparative Example 1, a battery was prepared in the same manner as the battery 1 of the embodiment except that an insulating film having a “cold xylene soluble content” of 17 wt% was used.

次に、実施例１〜６及び比較例１の各電池について、前述の「熱衝撃試験」を行って、試験後に電池を解体し、袋状絶縁部材の絶縁フィルムの状態をそれぞれ調査した。具体的には、目視にて絶縁フィルムを観察して、絶縁フィルムに破れが生じているか否かを判断した。その結果を表１に示す。   Next, about each battery of Examples 1-6 and the comparative example 1, the above-mentioned "thermal shock test" was performed, the battery was disassembled after the test, and the state of the insulating film of the bag-shaped insulating member was investigated. Specifically, the insulating film was visually observed to determine whether or not the insulating film was torn. The results are shown in Table 1.

Figure 2016189302
Figure 2016189302

表１から判るように、比較例１の電池では、絶縁フィルムに破れが生じていた。これに対し、実施例１〜６の各電池では、いずれの電池においても、絶縁フィルムに破れが生じていなかった。このことから、絶縁フィルムの「冷キシレン可溶分」を１６ｗｔ％以下にすると、「熱衝撃試験」を行っても絶縁フィルムに破れが生じるのを防止できると考えられる。   As can be seen from Table 1, in the battery of Comparative Example 1, the insulating film was broken. On the other hand, in each battery of Examples 1 to 6, the insulating film was not broken in any battery. From this, it is considered that when the “cold xylene soluble content” of the insulating film is 16 wt% or less, the insulating film can be prevented from being broken even if the “thermal shock test” is performed.

なお、「冷キシレン可溶分」を１６ｗｔ％以下にすると、「熱衝撃試験」で絶縁フィルムに破れが生じなくなる理由は、以下であると考えられる。即ち、前述のように、絶縁フィルム３１は、熱可塑性エラストマーを含有している。熱可塑性エラストマーは、その結晶性が低いと「冷キシレン」に溶解し易いが、結晶性が高いと「冷キシレン」に溶解し難い。このため、「冷キシレン可溶分」は、結晶性の低い熱可塑性エラストマーの含有割合を示す。この結晶性の低い熱可塑性エラストマーは、柔軟性が低く破壊され易いため、その含有割合が多くなると、破れ易くなる。具体的には、「冷キシレン可溶分」が１６ｗｔ％を越えると、「熱衝撃試験」において絶縁フィルムに破れが生じると考えられる。   If the “cold xylene soluble content” is 16 wt% or less, the reason why the insulating film does not break in the “thermal shock test” is considered as follows. That is, as described above, the insulating film 31 contains a thermoplastic elastomer. A thermoplastic elastomer is easily dissolved in “cold xylene” when its crystallinity is low, but is difficult to dissolve in “cold xylene” when its crystallinity is high. For this reason, “cold xylene soluble content” indicates the content of thermoplastic elastomer with low crystallinity. The thermoplastic elastomer having low crystallinity has low flexibility and is easily broken, and therefore, when the content is increased, the thermoplastic elastomer is easily broken. Specifically, when the “cold xylene soluble content” exceeds 16 wt%, it is considered that the insulating film is broken in the “thermal shock test”.

次に、実施例７〜１１として、「６０℃雰囲気下での降伏点強力」のみが互いに異なる絶縁フィルム３１で形成した袋状絶縁部材３０を用い、それ以外は実施形態の電池１と同様にした５種類の電池を用意した。具体的には、絶縁フィルムの「６０℃雰囲気下での降伏点強力」を、２．９Ｎ／１０ｍｍ（実施例７）、３．５Ｎ／１０ｍｍ（実施例８）、４．５Ｎ／１０ｍｍ（実施例９）、５．７Ｎ／１０ｍｍ（実施例１０）、または７．０Ｎ／１０ｍｍ（実施例１１）とした。なお、実施例９の電池は、前述した実施形態の電池１及び実施例３の電池と同じ絶縁フィルム３１を用いている。
一方、比較例２として、「６０℃雰囲気下での降伏点強力」が２．１Ｎ／１０ｍｍの絶縁フィルムを用い、また、比較例３として、「６０℃雰囲気下での降伏点強力」が７．８Ｎ／１０ｍｍの絶縁フィルムを用い、それ以外は実施形態の電池１と同様にした電池をそれぞれ用意した。 Next, as Examples 7 to 11, the bag-like insulating member 30 formed of the insulating films 31 different from each other only in “yield point strength at 60 ° C. atmosphere” is used, and other than that, similarly to the battery 1 of the embodiment. Five types of batteries were prepared. Specifically, the “yield point strength at 60 ° C. atmosphere” of the insulating film is 2.9 N / 10 mm (Example 7), 3.5 N / 10 mm (Example 8), 4.5 N / 10 mm (implemented). Example 9) 5.7 N / 10 mm (Example 10) or 7.0 N / 10 mm (Example 11). In addition, the battery of Example 9 uses the same insulating film 31 as the battery 1 of the embodiment described above and the battery of Example 3.
On the other hand, as Comparative Example 2, an insulating film having a yield strength at 60 ° C. of 2.1 N / 10 mm was used, and as Comparative Example 3, “Yield strength at 60 ° C.” was 7 Each battery was prepared in the same manner as the battery 1 of the embodiment except that an insulating film of 8 N / 10 mm was used.

次に、実施例７〜１１及び比較例２，３の各電池について、前述の「低温衝撃試験」を行って、試験後に電池を解体し、袋状絶縁部材の絶縁フィルムの状態をそれぞれ調査した。具体的には、目視にて絶縁フィルムを観察して、絶縁フィルムに微小な亀裂（クレーズ）が生じているか否かを判断した。その結果を表２に示す。   Next, for each of the batteries of Examples 7 to 11 and Comparative Examples 2 and 3, the aforementioned “low temperature impact test” was performed, the batteries were disassembled after the test, and the state of the insulating film of the bag-like insulating member was investigated. . Specifically, the insulating film was visually observed to determine whether or not a minute crack (craze) occurred in the insulating film. The results are shown in Table 2.

Figure 2016189302
Figure 2016189302

表２から判るように、比較例２，３の電池では、絶縁フィルムに微小な亀裂が生じていた。これに対し、実施例７〜１１の各電池では、いずれの電池においても、絶縁フィルムに微小な亀裂が生じていなかった。このことから、「６０℃雰囲気下での降伏点強力」が２．５〜７．４Ｎ／１０ｍｍの範囲内の絶縁フィルムを用いると、「低温衝撃試験」を行っても絶縁フィルムに微小な亀裂が生じるのを防止した電池を得られると考えられる。   As can be seen from Table 2, in the batteries of Comparative Examples 2 and 3, there were minute cracks in the insulating film. On the other hand, in each battery of Examples 7-11, the micro crack was not produced in the insulating film in any battery. For this reason, if an insulating film having a “yield point strength at 60 ° C.” in the range of 2.5 to 7.4 N / 10 mm is used, even if the “low temperature impact test” is performed, a minute crack is formed in the insulating film. It is considered that a battery that prevents the occurrence of the above can be obtained.

なお、「６０℃雰囲気下での降伏点強力」を２．５〜７．４Ｎ／１０ｍｍの範囲内にすると、「低温衝撃試験」で絶縁フィルムに微小な亀裂が生じなくなる理由は、以下であると考えられる。即ち、電池が低温状態で衝撃を受けたときに、絶縁フィルムに微小な亀裂が発生するのは、引っ張り試験により得られる降伏点強力と関係があることが判った。
具体的には、降伏点強力が小さすぎると、具体的には２．５Ｎ／１０ｍｍよりも小さいと、絶縁フィルムが降伏し易く、伸びて薄くなり、低温時に電池に衝撃が掛かったときに、拘束による面圧が加わる電極体近傍の部分で微小な亀裂が生じ易くなる。一方、降伏点強力が大きすぎると、具体的には７．４Ｎ／１０ｍｍよりも大きいと、絶縁フィルムの剛性が高すぎて、低温時に電池に衝撃が掛かったときに、絶縁フィルムに微小な亀裂が生じ易くなる。このことから、６０℃雰囲気下での降伏点強力は、２．５〜７．４Ｎ／１０ｍｍの範囲とするのが良い。 In addition, when the “yield point strength at 60 ° C. atmosphere” is in the range of 2.5 to 7.4 N / 10 mm, the reason why the microscopic cracks are not generated in the insulating film in the “low temperature impact test” is as follows. it is conceivable that. That is, it has been found that the occurrence of minute cracks in the insulating film when the battery is impacted at a low temperature is related to the yield point strength obtained by the tensile test.
Specifically, if the yield point strength is too small, specifically less than 2.5 N / 10 mm, the insulating film easily yields, becomes thin, and when the battery is impacted at low temperatures, Small cracks are likely to occur in the vicinity of the electrode body to which the surface pressure due to restraint is applied. On the other hand, if the yield point strength is too large, specifically greater than 7.4 N / 10 mm, the insulation film is too rigid, and when an impact is applied to the battery at a low temperature, a minute crack is formed in the insulation film. Is likely to occur. For this reason, the yield point strength at 60 ° C. is preferably in the range of 2.5 to 7.4 N / 10 mm.

加えて、６０℃という比較的高温下での降伏点強力を条件としたのは、低温では、絶縁フィルムが硬くなるため、異なる種類の絶縁フィルム間での降伏点強力の差が小さくなる。一方、例えば６０℃などの高温では、絶縁フィルムが軟化するので、異なる種類の絶縁フィルム間で、降伏点強力の差異が大きく現れるからである。従って、絶縁フィルムの「６０℃雰囲気下での降伏点強力」を規定することで、具体的には、「６０℃雰囲気下での降伏点強力」が２．５〜７．４Ｎ／１０ｍｍの絶縁フィルムを用いることで、「低温衝撃試験」で絶縁フィルムに微小な亀裂が生じるのを防止した電池を得られると考えられる。
なお、絶縁フィルムの厚みが厚い方が降伏点強力は大きくなるが、絶縁フィルムが厚いと、電池ケース内に収容する電極体の厚みを減らす必要がある。このことから、絶縁フィルムの厚みは、３０〜８０μｍの範囲とするのが好ましい。 In addition, the reason for the yield point strength at a relatively high temperature of 60 ° C. is that, since the insulating film becomes hard at low temperatures, the difference in yield point strength between different types of insulating films becomes small. On the other hand, because the insulating film softens at a high temperature such as 60 ° C., for example, a difference in yield point strength appears greatly between different types of insulating films. Therefore, by defining the “yield point strength in a 60 ° C. atmosphere” of the insulating film, specifically, the “yield point strength in a 60 ° C. atmosphere” is 2.5 to 7.4 N / 10 mm. By using the film, it is considered that a battery can be obtained in which minute cracks are prevented from occurring in the insulating film in the “low temperature impact test”.
In addition, the yield point strength increases as the thickness of the insulating film increases, but when the insulating film is thick, it is necessary to reduce the thickness of the electrode body accommodated in the battery case. For this reason, the thickness of the insulating film is preferably in the range of 30 to 80 μm.

以上で説明したように、電池１は、前述の絶縁フィルム３１からなる絶縁部材３０を備えるので、前述した「熱衝撃試験」や「低温衝撃試験」を行っても、絶縁フィルム３１に亀裂や破れが生じるのを防止できる。従って、この電池１は、電池ケース１０と電極体２０との間に介在させる絶縁部材３０の絶縁フィルム３１に亀裂や破れが生じ難く、信頼性が高い。更に、絶縁部材３０を袋状絶縁部材としているので、この袋状絶縁部材３０により電極体２０を確実に包囲して、電極体２０と電池ケース１０との間を確実に絶縁できる。   As described above, since the battery 1 includes the insulating member 30 formed of the insulating film 31 described above, the insulating film 31 is cracked or torn even if the above-described “thermal shock test” or “low temperature shock test” is performed. Can be prevented. Therefore, the battery 1 is highly reliable because the insulating film 31 of the insulating member 30 interposed between the battery case 10 and the electrode body 20 is hardly cracked or torn. Furthermore, since the insulating member 30 is a bag-shaped insulating member, the electrode body 20 is reliably surrounded by the bag-shaped insulating member 30, and the electrode body 20 and the battery case 10 can be reliably insulated.

以上において、本発明を実施形態に即して説明したが、本発明は上述の実施形態に限定されるものではなく、その要旨を逸脱しない範囲で、適宜変更して適用できることは言うまでもない。
例えば、実施形態では、溶着によって絶縁フィルム３１同士を固定して袋状絶縁部材３０を形成したが、これに限られない。例えば粘着テープや接着剤を用いて、絶縁フィルム３１同士を固定して袋状絶縁部材３０を形成してもよい。 In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the embodiment, the insulating films 31 are fixed to each other by welding to form the bag-shaped insulating member 30, but the present invention is not limited to this. For example, the bag-shaped insulating member 30 may be formed by fixing the insulating films 31 using an adhesive tape or an adhesive.

また、実施形態では、ポリプロピレン系樹脂とは別に、エチレン−α−オレフィン共重合体の熱可塑性エラストマー（具体的にはエチレン・プロピレンゴム）を含んだ絶縁フィルム３１を例示したが、これに限られない。絶縁フィルムは、ポリプロピレン系樹脂とは別に、エチレン−α−オレフィン共重合体の熱可塑性エラストマーを含まないものとしてもよい。この場合、ポリプロピレン系樹脂を単独で溶融し、Ｔダイやリングダイにより押出し冷却することでフィルムに成型することにより、絶縁フィルムを製造できる。   In the embodiment, the insulating film 31 containing an ethylene-α-olefin copolymer thermoplastic elastomer (specifically, ethylene / propylene rubber) is illustrated separately from the polypropylene resin, but is not limited thereto. Absent. The insulating film may contain no ethylene-α-olefin copolymer thermoplastic elastomer, apart from the polypropylene resin. In this case, an insulating film can be manufactured by melt | dissolving polypropylene-type resin independently, and shape | molding it by extruding and cooling with a T die or a ring die.

１ 電池（リチウムイオン二次電池）
１０ 電池ケース
２０ 電極体
３０ 袋状絶縁部材（絶縁部材）
３０ｈ （袋状絶縁部材の）開口部
３１ 絶縁フィルム
４０ 正極端子
４１ 負極端子 1 Battery (Lithium ion secondary battery)
10 battery case 20 electrode body 30 bag-like insulating member (insulating member)
30h Opening 31 (of bag-like insulating member) Insulating film 40 Positive electrode terminal 41 Negative electrode terminal

Claims (6)

金属製の電池ケースと、
上記電池ケース内に収容された電極体と、
絶縁フィルムからなり、上記電池ケースと上記電極体との間に介在して両者を絶縁する絶縁部材と、を備える
電池であって、
上記絶縁フィルムは、
ポリプロピレン系樹脂を主成分とし、
冷キシレン可溶分が１６ｗｔ％以下であり、かつ、６０℃雰囲気下での降伏点強力が２．５〜７．４Ｎ／１０ｍｍである
電池。 A metal battery case,
An electrode body housed in the battery case;
An insulating film comprising an insulating film and interposed between the battery case and the electrode body to insulate the battery,
The insulating film is
The main component is polypropylene resin,
A battery having a cold xylene soluble content of 16 wt% or less and a yield point strength in an atmosphere of 60 ° C. of 2.5 to 7.4 N / 10 mm. 請求項１に記載の電池であって、
前記絶縁フィルムは、前記ポリプロピレン系樹脂とは別に、エチレン−α−オレフィン共重合体の熱可塑性エラストマーを含有する
電池。 The battery according to claim 1,
The battery in which the insulating film contains a thermoplastic elastomer of an ethylene-α-olefin copolymer separately from the polypropylene resin. 請求項２に記載の電池であって、
前記絶縁フィルムは、未延伸フィルムであり、
前記絶縁部材は、上記絶縁フィルムを溶着して形成してなる
電池。 The battery according to claim 2,
The insulating film is an unstretched film,
The insulating member is a battery formed by welding the insulating film. 金属製の電池ケースと、
上記電池ケース内に収容された電極体と、
絶縁フィルムからなり、上記電池ケースと上記電極体との間に介在して両者を絶縁する絶縁部材と、を備える
電池に用いられる上記絶縁フィルムであって、
ポリプロピレン系樹脂を主成分とし、
冷キシレン可溶分が１６ｗｔ％以下であり、かつ、６０℃雰囲気下での降伏点強力が２．５〜７．４Ｎ／１０ｍｍである
絶縁フィルム。 A metal battery case,
An electrode body housed in the battery case;
An insulating film comprising an insulating film, and used for a battery comprising an insulating member interposed between the battery case and the electrode body to insulate both,
The main component is polypropylene resin,
An insulating film having a cold xylene-soluble content of 16 wt% or less and a yield point strength in an atmosphere of 60 ° C. of 2.5 to 7.4 N / 10 mm. 請求項４に記載の絶縁フィルムであって、
前記ポリプロピレン系樹脂とは別に、エチレン−α−オレフィン共重合体の熱可塑性エラストマーを含有する
絶縁フィルム。 The insulating film according to claim 4,
An insulating film containing a thermoplastic elastomer of an ethylene-α-olefin copolymer separately from the polypropylene resin. 請求項５に記載の絶縁フィルムであって、
前記電池の前記絶縁部材は、上記絶縁フィルムを溶着して形成してなり、
上記絶縁フィルムは、未延伸フィルムである
絶縁フィルム。 The insulating film according to claim 5,
The insulating member of the battery is formed by welding the insulating film,
The insulating film is an unstretched film.
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