JP2010040488A - Battery - Google Patents
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- JP2010040488A JP2010040488A JP2008205665A JP2008205665A JP2010040488A JP 2010040488 A JP2010040488 A JP 2010040488A JP 2008205665 A JP2008205665 A JP 2008205665A JP 2008205665 A JP2008205665 A JP 2008205665A JP 2010040488 A JP2010040488 A JP 2010040488A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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
Description
本発明は、捲回型の電池（例えばリチウムイオン二次電池）に関するものである。 The present invention relates to a wound battery (for example, a lithium ion secondary battery).
正極に金属酸化物、電解質に有機電解液（非水系電解液）、負極に黒鉛等の炭素材料、正極及び負極間に多孔質セパレータを用いるリチウムイオン二次電池（以下、単に電池とも呼ぶ）は、１９９１年に初めて製品化されて以来、そのエネルギー密度の高さから、小型、軽量化が進む携帯電話のような携帯機器向けの電池として急速に普及してきた。 A lithium ion secondary battery (hereinafter also simply referred to as a battery) using a metal oxide as a positive electrode, an organic electrolyte (non-aqueous electrolyte) as an electrolyte, a carbon material such as graphite as a negative electrode, and a porous separator between the positive electrode and the negative electrode Since it was first commercialized in 1991, it has rapidly spread as a battery for portable devices such as mobile phones that are becoming smaller and lighter due to its high energy density.
また、発電された電気を蓄えるために容量を大きくしたリチウムイオン二次電池（大容量電池）も研究されている。なお、この大容量電池としては、従来の電池を単にスケールアップして製造された例が報告されている。 In addition, lithium ion secondary batteries (large capacity batteries) having a large capacity for storing the generated electricity have been studied. In addition, as this large-capacity battery, the example manufactured only by scaling up the conventional battery is reported.
一方で、リチウムイオン二次電池の急速な普及や大容量化に伴い、その安全性に対する要望は高くなってきている。 On the other hand, with the rapid spread and increase in capacity of lithium ion secondary batteries, there is an increasing demand for safety.
リチウムイオン二次電池は、電解質として有機電解液を用いているため、過酷な使用条件においても破裂や発火等の事故に至らないように、いくつかの対策が施されている。その対策としては、電池温度が上昇した場合に、セパレータが溶融することによって、セパレータの孔が塞がり、その結果、電流が遮断される”シャットダウン機能”のような安全性を確保する対策が備えられている。 Since the lithium ion secondary battery uses an organic electrolyte as an electrolyte, some measures are taken so as not to cause an accident such as rupture or ignition even under severe use conditions. As a countermeasure, when the battery temperature rises, the separator melts to close the hole in the separator, and as a result, measures to ensure safety such as a “shutdown function” that cuts off the current are provided. ing.
しかしながら、これらの対策が施された電池であっても、電池の安全性に関する問題は生じている。例えば、外部からの要因による短絡（釘が刺さった場合等）や内部短絡（異物混入の場合等）が生じて、短絡箇所に電流が集中して流れると、抵抗発熱による発熱が生じ、その熱によって電池内の活物質や電解液の化学反応が引き起こされる。その結果、電池に、いわゆる“熱暴走”が起こり、最悪の場合には破裂、発火に至るといった問題が起こっている。 However, even with such a countermeasure, there is a problem regarding the safety of the battery. For example, if a short circuit due to an external factor (such as when a nail is pierced) or an internal short circuit (such as when a foreign object is mixed) occurs and current flows in the short circuit location, heat is generated due to resistance heat generation. Causes a chemical reaction between the active material and the electrolyte in the battery. As a result, so-called “thermal runaway” occurs in the battery, and in the worst case, the battery ruptures and ignites.
これまでに、内部短絡を防止できる安全性の高いリチウムイオン二次電池として、正極集電体の露出部と対向する負極合剤の表面、及び、負極合剤の表面と対向する正極集電体の露出部の少なくともいずれか一方の表面に絶縁体層を形成した非水系二次電池が開示・提案されている（例えば、特許文献１を参照）。
確かに、特許文献１に記載の従来技術は、電池の内部短絡防止に資するものであるが、長期の評価において、前記絶縁体層は、少なからず剥離や落下等を生じる懸念がある。そのため、特許文献１に記載の従来技術では、正極集電体の露出部と対向する負極合剤の表面、及び、負極合剤の表面と対向する正極集電体の露出部間の少なくともいずれかで、長期の使用において生じる内部短絡を十分に抑制することができなくなるおそれがあった。 Certainly, the prior art described in Patent Document 1 contributes to prevention of internal short circuit of the battery. However, in the long-term evaluation, there is a concern that the insulator layer is not a little peeled off or dropped. Therefore, in the prior art described in Patent Document 1, at least one of the surface of the negative electrode mixture facing the exposed portion of the positive electrode current collector and the exposed portion of the positive electrode current collector facing the surface of the negative electrode mixture. Therefore, there is a possibility that the internal short circuit that occurs during long-term use cannot be sufficiently suppressed.
本発明は、上記の問題点に鑑み、内部短絡を効果的に抑制してその安全性を高めることが可能な捲回型の電池を提供することを目的とする。 An object of this invention is to provide the winding type battery which can suppress an internal short circuit effectively and can improve the safety | security in view of said problem.
上記目的を達成するために、本発明に係る電池は、正極と負極とセパレータを一体とした捲回体を有して成る電池であって、前記正極及び前記負極のうち、少なくともいずれか一方は、その両面或いは片面に導電層が形成された樹脂フィルムを集電体としたものであり、かつ、前記樹脂フィルムは、前記捲回体の外周部分に、前記導電層が一切形成されない露出領域を有する構成（第１の構成）とされている。 In order to achieve the above object, a battery according to the present invention is a battery having a wound body in which a positive electrode, a negative electrode, and a separator are integrated, and at least one of the positive electrode and the negative electrode is The resin film having a conductive layer formed on both sides or one side is used as a current collector, and the resin film has an exposed region where no conductive layer is formed on the outer periphery of the wound body. It is set as the structure (1st structure) to have.
なお、上記第１の構成から成る電池において、前記樹脂フィルムは、前記捲回体の最外周部分にのみ、前記露出領域を有する構成（第２の構成）にするとよい。 In the battery having the first configuration, the resin film may have a configuration (second configuration) having the exposed region only at the outermost peripheral portion of the wound body.
また、上記第１または第２の構成から成る電池において、前記樹脂フィルムは、１２０℃での熱収縮率が縦、横いずれかの方向で１．５％以上の熱可塑性樹脂から成る構成（第３の構成）にするとよい。 Further, in the battery having the first or second configuration, the resin film is formed of a thermoplastic resin having a thermal shrinkage rate at 120 ° C. of 1.5% or more in either the vertical or horizontal direction (first configuration). 3).
また、上記第３の構成から成る電池において、前記樹脂フィルムは、ポリオレフィン樹脂、または、ポリ塩化ビニル、若しくは、これらの複合材料から成る構成（第４の構成）にするとよい。 In the battery having the third configuration, the resin film may have a configuration (fourth configuration) made of a polyolefin resin, polyvinyl chloride, or a composite material thereof.
正極及び負極の集電体が金属箔から成る従来構成の電池では、内部短絡を生じ易い箇所として、正極集電体の露出部と負極の表面との間、正極集電体の露出部と負極集電体の露出部との間、正極の表面と負極の表面との間、並びに、正極の表面と負極集電体の露出部との間を挙げることができる。なかでも、正極集電体の露出部と負極の表面との間は、内部短絡が生じた場合に、特に大きな電流が流れ易い箇所として考えられる。 In a battery having a conventional configuration in which the current collector of the positive electrode and the negative electrode is made of metal foil, the exposed portion of the positive electrode current collector and the surface of the negative electrode, the exposed portion of the positive electrode current collector, and the negative electrode are likely to cause an internal short circuit. Examples thereof include between the exposed portion of the current collector, between the surface of the positive electrode and the surface of the negative electrode, and between the surface of the positive electrode and the exposed portion of the negative electrode current collector. In particular, it is considered that a particularly large current easily flows between the exposed portion of the positive electrode current collector and the surface of the negative electrode when an internal short circuit occurs.
これに対して、本発明に係る電池であれば、正極及び前記負極のうち、少なくともいずれか一方は、その両面或いは片面に導電層が形成された樹脂フィルムを集電体としたものであり、かつ、前記樹脂フィルムは、捲回体の外周部分に、導電層が一切形成されない露出領域を有しているので、正極集電体の露出部と負極の表面との間で内部短絡を生じにくい構造となる。 On the other hand, in the case of the battery according to the present invention, at least one of the positive electrode and the negative electrode is a collector made of a resin film having a conductive layer formed on both sides or one side thereof, And since the said resin film has the exposure area | region where a conductive layer is not formed at all in the outer peripheral part of a winding body, it is hard to produce an internal short circuit between the exposed part of a positive electrode electrical power collector, and the surface of a negative electrode. It becomes a structure.
さらに、本発明に係る電池であれば、サイクル中に生じる電極の膨張収縮にも、樹脂フィルムの伸縮で対応することができるので、サイクル特性に及ぼす効果も大きくなる。 Furthermore, in the case of the battery according to the present invention, the expansion and contraction of the electrode occurring during the cycle can be dealt with by the expansion and contraction of the resin film, so that the effect on the cycle characteristics is also increased.
また、本発明に係る電池であれば、正極及び負極の集電体が金属箔から成る従来構成の電池と比べて、金属の使用量を低減することができる。その結果、電池の軽量化、金属の使用量低減による低コスト化が可能となる。 Moreover, if it is a battery which concerns on this invention, the usage-amount of a metal can be reduced compared with the battery of the conventional structure from which the electrical power collector of a positive electrode and a negative electrode consists of metal foil. As a result, it is possible to reduce the cost by reducing the weight of the battery and reducing the amount of metal used.
以下では、本発明を捲回型のリチウムイオン二次電池に適用した構成を例に挙げて、詳細な説明を行う。 Hereinafter, a configuration in which the present invention is applied to a wound lithium ion secondary battery will be described in detail as an example.
図１は、本発明に係る捲回型のリチウムイオン二次電池の縦断面図である。図１に示すように、本発明に係るリチウムイオン二次電池１０は、正極１１と、負極１２と、セパレータ１３と、正極リード１４と、負極リード１５と、電池缶１６と、正極蓋１７と、絶縁パッキン１８と、センターピン１９と、を有して成る。なお、図１において、セパレータ１３、正極蓋１７、及び、絶縁パッキン１８には断面を示すハッチングを省略している。 FIG. 1 is a longitudinal sectional view of a wound lithium ion secondary battery according to the present invention. As shown in FIG. 1, a lithium ion secondary battery 10 according to the present invention includes a positive electrode 11, a negative electrode 12, a separator 13, a positive electrode lead 14, a negative electrode lead 15, a battery can 16, and a positive electrode lid 17. Insulating packing 18 and center pin 19 are provided. In FIG. 1, hatching indicating a cross section is omitted from the separator 13, the positive electrode lid 17, and the insulating packing 18.
上記の構成要素を有するリチウムイオン二次電池１０の電極構造は、次の通りである。正極１１と負極１２との間には、それぞれ多孔質のセパレータ１３が挟まれている。そして、これらを一体として端からスパイラル状に捲回することにより、円筒形の捲回体が形成される。この捲回体は、電池缶１６の上面側（正極蓋１７側）から正極リード１４、底面側から負極リード１５がそれぞれ引き出された状態で、円筒形の電池缶１６（例えば、直径１８［ｍｍ］、高さ６５［ｍｍ］）内に収納されている。 The electrode structure of the lithium ion secondary battery 10 having the above constituent elements is as follows. A porous separator 13 is sandwiched between the positive electrode 11 and the negative electrode 12, respectively. And these are united and wound from the end in a spiral shape, whereby a cylindrical wound body is formed. The wound body has a cylindrical battery can 16 (for example, a diameter of 18 [mm], with the positive electrode lead 14 and the negative electrode lead 15 drawn from the upper surface side (positive electrode lid 17 side) of the battery can 16 and the bottom surface side, respectively. ], The height is 65 [mm]).
また、正極リード１４は正極蓋１７に、負極リード１５は電池缶１６の底面に、スポット溶接によってそれぞれ取り付けられている。また、上記捲回体の中心部には、巻き崩れ防止のためにセンターピン１９が挿入されている。また、電池缶１６と正極蓋１７との間は、絶縁パッキン１８を介在させた状態で、かしめによる密封処理が施されている。 The positive electrode lead 14 is attached to the positive electrode lid 17 and the negative electrode lead 15 is attached to the bottom surface of the battery can 16 by spot welding. A center pin 19 is inserted in the center of the wound body to prevent the winding body from collapsing. Further, the battery can 16 and the positive electrode lid 17 are sealed by caulking with an insulating packing 18 interposed therebetween.
セパレータ１３は、例えば、電気絶縁性の合成樹脂繊維、ガラス繊維、天然繊維等の不織布、織布、又は、微多孔質膜の中から適宜選択可能である。なかでも、ポリエチレン、ポリプロピレン、ポリエステル等の不織布、及び、微多孔質膜は、品質の安定性等の点から、セパレータ１３として好適に使用することができる。また、上記合成樹脂の不織布、及び、微多孔質膜をセパレータ１３として用いれば、リチウムイオン二次電池１０が異常発熱した場合にセパレータ１３が熱により溶解し、正極１１と負極１２との間で電流が遮断される機能、いわゆる”シャットダウン機能”を付加することが可能となる。従って、安全性の観点から見ても、上記合成樹脂の不織布、及び、微多孔質膜は、セパレータ１３として好適に使用することができる。 The separator 13 can be appropriately selected from, for example, electrically insulating synthetic resin fibers, glass fibers, nonwoven fabrics such as natural fibers, woven fabrics, or microporous membranes. Especially, nonwoven fabrics, such as polyethylene, a polypropylene, and polyester, and a microporous film can be used conveniently as the separator 13 from points, such as stability of quality. Moreover, if the synthetic resin nonwoven fabric and the microporous membrane are used as the separator 13, when the lithium ion secondary battery 10 abnormally generates heat, the separator 13 is melted by heat, and between the positive electrode 11 and the negative electrode 12. It is possible to add a function of interrupting current, a so-called “shutdown function”. Therefore, from the viewpoint of safety, the synthetic resin nonwoven fabric and the microporous membrane can be suitably used as the separator 13.
なお、セパレータ１３の厚みについては、特に限定されないが、必要量の電解液を保持することが可能であって、かつ、正極１１と負極１２との短絡を防ぐことが可能な厚さがあればよい。例えば、０．０１〜１［ｍｍ］程度の厚さとすればよく、好ましくは、０．０２〜０．０５［ｍｍ］程度の厚さとすればよい。 The thickness of the separator 13 is not particularly limited as long as it has a thickness capable of holding a necessary amount of electrolyte and preventing a short circuit between the positive electrode 11 and the negative electrode 12. Good. For example, the thickness may be about 0.01 to 1 [mm], and preferably about 0.02 to 0.05 [mm].
また、セパレータ１３を構成する材質についても、特に限定されないが、電池の内部抵抗値を小さく維持しつつ、電池の内部短絡を防ぐことが可能な強度を確保するために、１〜５００［秒／ｃｍ３］程度の透気度を有する材質を用いることが好ましい。 Further, the material constituting the separator 13 is not particularly limited, but in order to ensure the strength capable of preventing the internal short circuit of the battery while maintaining the internal resistance value of the battery small, 1 to 500 [second / second]. It is preferable to use a material having an air permeability of about cm 3 ].
また、セパレータ１３の形状や大きさについても、特に限定されないが、正極１１及び負極１２と共に捲回した場合に、正極１１よりも大きいことが好ましく、なかでも、正極１１よりもやや大きく、負極１２よりもやや小さな相似形であることが好ましい。 Further, the shape and size of the separator 13 are not particularly limited, but when wound together with the positive electrode 11 and the negative electrode 12, it is preferably larger than the positive electrode 11, and in particular, slightly larger than the positive electrode 11. It is preferable that the shape is a little smaller than that.
また、リチウムイオン二次電池１０に含まれる電解質としては、一般に、有機溶媒と電解質塩とを含む非水系電解液が使用される。 Further, as the electrolyte contained in the lithium ion secondary battery 10, a non-aqueous electrolyte solution containing an organic solvent and an electrolyte salt is generally used.
なお、上記有機溶媒としては、プロピレンカーボネート（ＰＣ）、エチレンカーボネート（ＥＣ）、ブチレンカーボネート等の環状カーボネート類と、ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート、ジプロピルカーボネート等の鎖状カーボネート類、γ−ブチロラクトン、γ−バレロラクトン等のラクトン類、テトラヒドロフラン、２−メチルテトラヒドロフラン等のフラン類、ジエチルエーテル、１，２−ジメトキシエタン、１，２−ジエトキシエタン、エトキシメトキシエタン、ジオキサン等のエーテル類、ジメチルスルホキシド、スルホラン、メチルスルホラン、アセトニトリル、ギ酸メチル、酢酸メチル等が挙げられる。これら有機溶媒は、２種以上混合してもよい。 Examples of the organic solvent include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and dipropyl carbonate; -Lactones such as butyrolactone and γ-valerolactone, furans such as tetrahydrofuran and 2-methyltetrahydrofuran, ethers such as diethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane and dioxane Dimethyl sulfoxide, sulfolane, methyl sulfolane, acetonitrile, methyl formate, methyl acetate and the like. Two or more of these organic solvents may be mixed.
また、上記電解質塩としては、ホウフッ化リチウム（ＬｉＢＦ４）、リンフッ化リチウム（ＬｉＰＦ６）、トリフルオロメタンスルホン酸リチウム（ＬｉＣＦ３ＳＯ３）、トリフルオロ酢酸リチウム（ＬｉＣＦ３ＣＯＯ）、トリフルオロメタンスルホン酸イミドリチウム（ＬｉＮ（ＣＦ３ＳＯ２）２）等のリチウム塩が挙げられる。これら電解質塩は、２種以上を混合してもよい。 Examples of the electrolyte salt include lithium borofluoride (LiBF 4 ), lithium phosphofluoride (LiPF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium trifluoroacetate (LiCF 3 COO), and trifluoromethanesulfonic acid. Examples thereof include lithium salts such as imidolithium (LiN (CF 3 SO 2 ) 2 ). Two or more of these electrolyte salts may be mixed.
また、上記の非水系電解液をポリマーマトリックス中に保持したゲル電解質や、イオン液体から成る電解質を用いることも可能である。 Moreover, it is also possible to use the gel electrolyte which hold | maintained said nonaqueous electrolyte solution in the polymer matrix, and the electrolyte which consists of an ionic liquid.
次に、正極１１及び負極１２の電極構造について説明する。本発明に係るリチウムイオン二次電池１０において、捲回体を形成する正極１１及び負極１２のうち、少なくともいずれか一方は、その表面に導電層が形成された樹脂フィルムを集電体としたものであり、かつ、上記の樹脂フィルムは、捲回体の外周部分に、導電層が一切形成されない露出領域を有する構造とされている。以下では、この特徴的な構造について、詳細な説明を行う。 Next, the electrode structure of the positive electrode 11 and the negative electrode 12 will be described. In the lithium ion secondary battery 10 according to the present invention, at least one of the positive electrode 11 and the negative electrode 12 forming a wound body is a resin film having a conductive layer formed on the surface thereof as a current collector. And said resin film is set as the structure which has the exposed area | region where a conductive layer is not formed at all in the outer peripheral part of a winding body. Hereinafter, this characteristic structure will be described in detail.
図２及び図３は、それぞれ、捲回体の横断面図（捲回軸に対して垂直方向に切断した場合の断面図）である。なお、図２には、正極１１及び負極１２の断面構造を詳細に説明するために、正極１１及び負極１２をシート状に広げた状態（捲回する前の状態）が示されている。一方、図３には、電池缶１６内部における正極１１及び負極１２の相対的な位置関係を詳細に説明するために、正極１１及び負極１２を捲回した状態が示されている。なお、図３では、正極１１が実線で示されており、負極１２が破線で示されている。 2 and 3 are cross-sectional views of the wound body (cross-sectional views when cut in a direction perpendicular to the winding axis), respectively. FIG. 2 shows a state in which the positive electrode 11 and the negative electrode 12 are spread in a sheet shape (a state before winding) in order to explain the cross-sectional structures of the positive electrode 11 and the negative electrode 12 in detail. On the other hand, FIG. 3 shows a state in which the positive electrode 11 and the negative electrode 12 are wound in order to explain the relative positional relationship between the positive electrode 11 and the negative electrode 12 in the battery can 16 in detail. In FIG. 3, the positive electrode 11 is indicated by a solid line, and the negative electrode 12 is indicated by a broken line.
図２に示すように、正極１１は、その両面に導電層１１ｙが形成された樹脂フィルム１１ｘを集電体としている。また、負極１２は、その両面に導電層１２ｙが形成された樹脂フィルム１２ｘを集電体としている。なお、導電層１１ｙ及び導電層１２ｙの形成方法については、特に限定されないが、蒸着、スパッタリング、無電解めっき等の方法を用いることができる。また、正極１１の導電層１１ｙを形成する導電性材料としては、アルミニウムを用いることが好ましく、負極１２の導電層１２ｙを形成する導電性材料としては、銅或いはニッケルを用いることが好ましい。また、導電層１１ｙ及び導電層１２ｙの厚さについては、電池の負荷特性を鑑みて０．３［μｍ］以上とすることが好ましく、また、導電性材料の使用量低減を鑑みて３［μｍ］以下とすることが好ましい。 As shown in FIG. 2, the positive electrode 11 uses a resin film 11x having a conductive layer 11y formed on both sides as a current collector. Further, the negative electrode 12 uses a resin film 12x having a conductive layer 12y formed on both surfaces thereof as a current collector. Note that a method for forming the conductive layer 11y and the conductive layer 12y is not particularly limited, and methods such as vapor deposition, sputtering, and electroless plating can be used. Further, aluminum is preferably used as the conductive material for forming the conductive layer 11y of the positive electrode 11, and copper or nickel is preferably used as the conductive material for forming the conductive layer 12y of the negative electrode 12. In addition, the thickness of the conductive layer 11y and the conductive layer 12y is preferably set to 0.3 [μm] or more in view of the load characteristics of the battery, and 3 [μm] in view of reduction of the amount of the conductive material used. The following is preferable.
なお、上記では、正極１１、負極１２の端部にそれぞれ１箇所ずつリード取り出し箇所（タブ接続部）を載置した構成を例に挙げて説明を行ったが、タブ接続部の載置位置や載置数は、これに限定されるものではない。例えば、導電層や活物質層が形成された集電体での抵抗ロスを鑑みると、電極端部に１箇所だけタブ接続部を載置した上記の構成では、タブ接続部から集電体最遠部（タブ接続部を起点としてそこから最も遠い位置にある集電体の一部分を指すものであって、上記の構成に即して言えば、タブ接続部が載置された電極端部とは逆側の電極端部に相当）までの距離が大きくなるので、集電体での抵抗ロスも大きくなる。そこで、さらなる電池特性の向上を図る場合には、タブ接続部から集電体最遠部までの距離を短縮して、集電体での抵抗ロスを抑制するために、電極端部以外（例えば電極両端からの距離が等しくなる中間位置）にタブ接続部を載置したり、若しくは、電極上の２箇所以上にタブ接続部を載置することが好ましい。なお、このような構成を採用する場合、負極１２のタブ接続部に対向する箇所には、正極１１の活物質層が存在しないように設計することが好ましい。また、このような構成は、正極側、負極側のいずれにも適用することが可能であるが、正極側に適用することがより好ましい。 In the above description, the configuration in which one lead take-out place (tab connection part) is placed on each of the end portions of the positive electrode 11 and the negative electrode 12 has been described as an example. The number of placement is not limited to this. For example, in view of resistance loss in a current collector on which a conductive layer or an active material layer is formed, in the above configuration in which only one tab connection portion is placed on the electrode end, the current collector is connected to the current collector from the tab connection portion. Distant part (refers to a part of the current collector that is located farthest from the tab connection part as a starting point. According to the above configuration, the electrode end part on which the tab connection part is mounted) Corresponds to the electrode end on the opposite side), and the resistance loss at the current collector also increases. Therefore, when further improving the battery characteristics, in order to reduce the distance from the tab connection part to the farthest part of the current collector and suppress the resistance loss at the current collector, It is preferable to place the tab connection part at an intermediate position where the distances from both ends of the electrode are equal, or to place the tab connection part at two or more locations on the electrode. In addition, when employ | adopting such a structure, it is preferable to design so that the active material layer of the positive electrode 11 may not exist in the location facing the tab connection part of the negative electrode 12. FIG. Such a configuration can be applied to either the positive electrode side or the negative electrode side, but is more preferably applied to the positive electrode side.
樹脂フィルム１１ｘ及び樹脂フィルム１２ｘの材質としては、熱可塑性樹脂から成るプラスチック材料が好ましく、例えば、熱変形温度が１５０℃以下であるポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等のポリオレフィン樹脂、ポリスチレン（ＰＳ）、ポリ塩化ビニル、ポリアミドを好適に用いることができる。なかでも、１２０℃での熱収縮率が縦、横いずれかの方向で１．５％以上のポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等のポリオレフィン樹脂、ポリ塩化ビニルが好ましい。また、これらの複合フィルムや、これらに表面加工処理を行った樹脂フィルムも好適に用いることができる。また、セパレータ１３と同じ材質から成る樹脂フィルムを用いることもできる。 The material of the resin film 11x and the resin film 12x is preferably a plastic material made of a thermoplastic resin. For example, a polyolefin resin such as polyethylene (PE) or polypropylene (PP) having a thermal deformation temperature of 150 ° C. or lower, polystyrene (PS ), Polyvinyl chloride, and polyamide can be preferably used. Of these, polyolefin resins such as polyethylene (PE) and polypropylene (PP) and polyvinyl chloride having a heat shrinkage rate at 120 ° C. of 1.5% or more in either the vertical or horizontal direction are preferable. Moreover, these composite films and resin films obtained by subjecting these composite films to surface treatment can also be suitably used. A resin film made of the same material as the separator 13 can also be used.
なお、上記熱収縮率の測定は次のように行えばよい。まず、樹脂フィルム上に５０［ｍｍ］以上の間隔を空けて２つのポイントを付け、両者のポイント間距離を測定する。その後、１５分間、１２０℃で加熱処理を行った後に、再度、同じポイント間距離を測定し、加熱処理前後の測定値に基づいて熱収縮率を求める。この方法に基づき、樹脂フィルムの縦方向及び横方向について、それぞれ３つ以上のポイント間距離を測定し、各々の測定結果から算出された熱収縮率の平均値を最終的な樹脂フィルムの熱収縮率として採用する。このとき、樹脂フィルムの縦方向及び横方向のそれぞれについて、少なくとも、樹脂フィルムの端部から１０％以内の２点と、樹脂フィルムの端部から５０％前後の１点を、ポイント間距離の測定地点として選定すべきである。 In addition, what is necessary is just to perform the measurement of the said heat contraction rate as follows. First, two points are provided on the resin film with an interval of 50 [mm] or more, and the distance between the two points is measured. Then, after heat-processing for 15 minutes at 120 degreeC, the distance between the same points is measured again, and a thermal contraction rate is calculated | required based on the measured value before and behind heat processing. Based on this method, measure the distance between three or more points in the longitudinal direction and lateral direction of the resin film, respectively, and calculate the average value of the thermal shrinkage calculated from each measurement result as the final thermal shrinkage of the resin film. Adopt as a rate. At this time, for each of the longitudinal direction and the lateral direction of the resin film, at least two points within 10% from the end of the resin film and one point around 50% from the end of the resin film are measured for the distance between the points. It should be selected as a point.
樹脂フィルム１１ｘ及び樹脂フィルム１２ｘの厚さについては、二次電池としてのエネルギー密度向上と強度維持のバランスを取るべく、１０［μｍ］以上、１００［μｍ］以下とすることが望ましい。樹脂フィルム１１ｘ及び樹脂フィルム１２ｘの製造方法については、一軸延伸、二軸延伸、または、無延伸等のいずれの方法を採用しても構わない。 About the thickness of the resin film 11x and the resin film 12x, it is desirable to set it as 10 [micrometers] or more and 100 [micrometers] or less in order to balance the energy density improvement and strength maintenance as a secondary battery. About the manufacturing method of the resin film 11x and the resin film 12x, you may employ | adopt any methods, such as uniaxial stretching, biaxial stretching, or non-stretching.
上記構成から成る正極１１において、導電層１１ｙ上には、正極活物質を含む正極活物質層（正極合剤層）１１ｚが形成される。また、上記構成から成る負極１２において、導電層１２ｙ上には、負極活物質を含む負極活物質層（負極合剤層）１２ｚが形成される。 In the positive electrode 11 having the above structure, a positive electrode active material layer (positive electrode mixture layer) 11z containing a positive electrode active material is formed on the conductive layer 11y. In the negative electrode 12 having the above-described configuration, a negative electrode active material layer (negative electrode mixture layer) 12z containing a negative electrode active material is formed on the conductive layer 12y.
なお、正極活物質としては、リチウムを含有した酸化物が挙げられる。具体的には、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＦｅＯ２、ＬｉＭｎＯ２、ＬｉＭｎ２Ｏ４、及び、これら正極活物質の遷移金属を一部他の金属元素で置換した物が挙げられる。また、通常の使用において、正極活物質が保有するリチウム量の８０％以上を電池反応に利用することが可能なものであれば、過充電による課題を解決し、電池の安全性を高めることが可能となる。このような正極活物質としては、ＬｉＭｎ２Ｏ４のようなスピネル構造を有するものや、ＬｉＭＰＯ４（ＭはＣｏ、Ｎｉ、Ｍｎ、Ｆｅから選ばれる少なくとも１種以上の元素）で表されるオリビン構造を有する正極材料等がある。なかでも、ＭｎやＦｅを用いた正極活物質がコストの観点から好ましい。 In addition, as a positive electrode active material, the oxide containing lithium is mentioned. Specific examples include LiCoO 2 , LiNiO 2 , LiFeO 2 , LiMnO 2 , LiMn 2 O 4 , and those obtained by partially replacing the transition metal of these positive electrode active materials with other metal elements. In addition, if it is possible to use 80% or more of the lithium content of the positive electrode active material in the battery reaction in normal use, the problem due to overcharging can be solved and the safety of the battery can be improved. It becomes possible. Examples of such a positive electrode active material include those having a spinel structure such as LiMn 2 O 4 and olivine represented by LiMPO 4 (M is at least one element selected from Co, Ni, Mn, and Fe). Examples include a positive electrode material having a structure. Especially, the positive electrode active material using Mn and Fe is preferable from a viewpoint of cost.
また、さらに好ましい正極活物質としては、安全性及び充電電圧の観点から、ＬｉＦｅＰＯ４が挙げられる。通常、電池に温度上昇が生じると、これに伴って正極活物質が酸素を放出するので、電解液が燃焼してさらに激しい発熱を生じてしまうが、ＬｉＦｅＰＯ４は、全ての酸素が強固な共有結合によって燐と結合しているため、電池に温度上昇が生じた場合でも、酸素の放出が非常に起こりにくく、安全性の観点から好ましい。また、ＬｉＦｅＰＯ４は燐を含んでいるため、消炎作用も期待できる。 Further, a more preferable positive electrode active material includes LiFePO 4 from the viewpoints of safety and charging voltage. Normally, when the temperature rises in the battery, the positive electrode active material releases oxygen along with this, so that the electrolyte solution burns and generates more intense heat generation. However, LiFePO 4 has a strong share of all oxygen. Since it is bonded to phosphorus by bonding, even when the temperature rises in the battery, oxygen is hardly released, which is preferable from the viewpoint of safety. Moreover, since LiFePO 4 contains phosphorus, it can be expected to have a flame-extinguishing action.
さらに、ＬｉＦｅＰＯ４は、その充電電圧が３．５［Ｖ］程度であり、３．８［Ｖ］でほぼ充電が完了するため、電解液の分解を引き起こす電圧レベルまでは少し余裕がある。従って、ＬｉＦｅＰＯ４を正極活物質として用いれば、規定された負荷特性に電極の分極があったとしても、充電電圧を適切なレベルまで高めることにより、電解液の分解を引き起こすことなく充電が可能となる。一方、充電電圧が４［Ｖ］以上に達するような正極活物質を用いた場合には、それ以上に充電電圧を上げると、電解液の分解が起こりやすくなる。そのため、上記のように分極が大きい場合に、さらに充電電圧を上げて充電すると、サイクル特性に影響を及ぼすおそれがあり、好ましくない。 Furthermore, LiFePO 4 has a charging voltage of about 3.5 [V], and charging is almost completed at 3.8 [V]. Therefore, there is a little margin to the voltage level that causes decomposition of the electrolytic solution. Therefore, if LiFePO 4 is used as the positive electrode active material, charging can be performed without causing decomposition of the electrolytic solution by increasing the charging voltage to an appropriate level even if there is polarization of the electrode in the specified load characteristics. Become. On the other hand, when a positive electrode active material whose charging voltage reaches 4 [V] or higher is used, if the charging voltage is further increased, the electrolytic solution is likely to be decomposed. For this reason, when the polarization is large as described above, if the charging voltage is further increased and charging is performed, cycle characteristics may be affected, which is not preferable.
また、ＬｉＦｅＰＯ４は、充電の末期に電圧が急激に上昇するため、満充電状態の検出が非常に行いやすく、組み電池にした場合にも、電圧検出の精度があまり要求されることがないという利点も有する。 In addition, since the voltage of LiFePO 4 rises sharply at the end of charging, it is very easy to detect the fully charged state, and even when an assembled battery is used, the accuracy of voltage detection is not so required. There are also advantages.
一方、負極活物質としては、天然黒鉛、粒子状（鱗片状ないし塊状、繊維状、ウイスカー状、球状、破砕状等）の人造黒鉛、或いは、メソカーボンマイクロビーズ、メソフェーズピッチ粉末、等方性ピッチ粉末等の黒鉛化品等に代表される高結晶性黒鉛、若しくは、樹脂焼成炭等の難黒鉛化炭素等が挙げられ、さらにはこれらを２種以上混合してもよい。また、錫の酸化物、シリコン系の負極活物質等の容量の大きい合金系の材料を使用することもできる。 On the other hand, as the negative electrode active material, natural graphite, particulate (scalar or lump, fiber, whisker, spherical, crushed, etc.) artificial graphite, mesocarbon microbead, mesophase pitch powder, isotropic pitch, etc. Examples thereof include highly crystalline graphite typified by graphitized products such as powder, non-graphitizable carbon such as resin-fired charcoal, and the like, and two or more thereof may be mixed. In addition, an alloy material having a large capacity such as a tin oxide or a silicon-based negative electrode active material may be used.
また、図２及び図３に示したように、本発明に係るリチウムイオン二次電池１０において、正極１１の集電体を形成する樹脂フィルム１１ｘは、捲回体の最外周部分（符号ｂ〜ｃで示された区間）に、導電層１１ｙが一切形成されない露出領域（非導電領域）を有する構成とされている。この露出領域は、導電層１１ｙの形成工程において、パターニングを行うことにより作成すればよい。パターニングの方法としては、マスクを用いる方法など、一般的に用いられている方法で対応することができる。 Moreover, as shown in FIG.2 and FIG.3, in the lithium ion secondary battery 10 which concerns on this invention, the resin film 11x which forms the electrical power collector of the positive electrode 11 is the outermost periphery part (code | symbol b-) of the winding body. The section indicated by c) has an exposed area (non-conductive area) where no conductive layer 11y is formed. This exposed region may be created by patterning in the step of forming the conductive layer 11y. As a patterning method, a generally used method such as a method using a mask can be used.
なお、上記した捲回体の「最外周部分」とは、符号ａで示すポイントを起点とし、センターピン１９を捲回軸として、スパイラル状に捲回体を形成したときに、最後に巻き取られる１周分（符号ｂ〜ｃで示された区間）を指すものとする。 The “outermost peripheral portion” of the wound body described above is the last winding when the wound body is formed in a spiral shape with the point indicated by symbol a as a starting point and the center pin 19 as a winding shaft. It is assumed that it indicates one round (a section indicated by reference numerals b to c).
また、図３において、極太線Ｘで示された領域は、樹脂フィルム上に導電層と活物質層が形成された領域を示している。太線Ｙで示された領域は、樹脂フィルム上に導電層のみが形成された領域（電極領域）を示している。細線Ｚで示された領域は、樹脂フィルム上に導電層が形成されていない露出領域（非導電領域）を示している。また、図３中の符号ａ〜ｃは、それぞれ、図２中の符号ａ〜ｃに相当する。 Moreover, in FIG. 3, the area | region shown with the very thick line X has shown the area | region where the conductive layer and the active material layer were formed on the resin film. A region indicated by a thick line Y indicates a region (electrode region) where only a conductive layer is formed on the resin film. A region indicated by a thin line Z indicates an exposed region (non-conductive region) where a conductive layer is not formed on the resin film. Also, reference symbols a to c in FIG. 3 correspond to reference symbols a to c in FIG. 2, respectively.
このように、本発明に係るリチウムイオン二次電池１０において、正極１１の集電体を形成する樹脂フィルム１１ｘは、捲回体の最外周部分に、導電層１１ｙが一切形成されない露出領域を有しているので、この露出領域と負極１２との間では、内部短絡を生じるおそれがない。従って、集電体が金属箔で形成されていた従来構成と異なり、電池の内部短絡を生じた場合であっても、正極集電体の露出領域と負極との間に大電流が流れることを防止できるので、電池の安全性向上に大きく寄与することが可能となる。 Thus, in the lithium ion secondary battery 10 according to the present invention, the resin film 11x forming the current collector of the positive electrode 11 has an exposed region where no conductive layer 11y is formed at the outermost peripheral portion of the wound body. Therefore, there is no possibility of causing an internal short circuit between the exposed region and the negative electrode 12. Therefore, unlike the conventional configuration in which the current collector is formed of a metal foil, a large current flows between the exposed region of the positive electrode current collector and the negative electrode even when an internal short circuit of the battery occurs. Therefore, it is possible to greatly contribute to improving the safety of the battery.
また、本発明に係るリチウムイオン二次電池１０では、捲回体の最外周部分にのみ樹脂フィルム１１ｘの露出領域が形成されているので、電池容量を不要に損なうことがない。 Further, in the lithium ion secondary battery 10 according to the present invention, since the exposed region of the resin film 11x is formed only at the outermost peripheral portion of the wound body, the battery capacity is not unnecessarily impaired.
さらに、本発明に係るリチウムイオン二次電池１０であれば、サイクル中に生じる電極の膨張収縮にも、樹脂フィルム１１ｘ、１２ｘの伸縮で対応することができるので、サイクル特性に及ぼす効果も大きくなる。 Furthermore, with the lithium ion secondary battery 10 according to the present invention, the expansion and contraction of the electrodes that occur during the cycle can be handled by the expansion and contraction of the resin films 11x and 12x, so that the effect on the cycle characteristics is also increased. .
また、本発明に係るリチウムイオン二次電池１０であれば、正極１１及び負極１２の集電体が金属箔から成る従来構成の電池と比べて、金属の使用量を低減することができる。その結果、電池の軽量化、金属の使用量低減による低コスト化が可能となる。 In addition, the lithium ion secondary battery 10 according to the present invention can reduce the amount of metal used compared to a battery having a conventional configuration in which the current collectors of the positive electrode 11 and the negative electrode 12 are made of metal foil. As a result, it is possible to reduce the cost by reducing the weight of the battery and reducing the amount of metal used.
なお、上記の実施形態では、本発明を捲回型のリチウムイオン二次電池に適用した構成を例示して詳細な説明を行ったが、本発明の適用対象はこれに限定されるものではなく、捲回型の電池全般に広く適用することが可能である。 In the above embodiment, a detailed description has been given by exemplifying a configuration in which the present invention is applied to a wound lithium ion secondary battery. However, the scope of application of the present invention is not limited to this. It can be widely applied to all types of wound type batteries.
また、本発明の構成は、上記実施形態のほか、発明の主旨を逸脱しない範囲で種々の変更を加えることが可能である。 The configuration of the present invention can be variously modified within the scope of the present invention in addition to the above embodiment.
例えば、上記実施形態では、正極１１と負極１２の両方に樹脂フィルム１１ｘ、１２ｘを用いた構成を例に挙げて説明を行ったが、本発明の構成はこれに限定されるものではなく、いずれか一方のみに樹脂フィルムを用い、他方については従来通りの金属箔を用いる構成としても構わない。 For example, in the said embodiment, although demonstrated taking the example of the structure which used resin film 11x, 12x for both the positive electrode 11 and the negative electrode 12, the structure of this invention is not limited to this, A resin film may be used for only one of them, and a conventional metal foil may be used for the other.
また、上記実施形態では、捲回体の最外周部分（図２及び図３の符号ｂ〜ｃで示された区間）にのみ、樹脂フィルム１１ｘの露出領域を形成する構成を例に挙げて説明を行ったが、本発明の構成はこれに限定されるものではなく、図４に示すように、樹脂フィルム１１ｘの露出領域を符号ｂで示すポイントよりもさらに内側の符号ｄで示すポイントから形成した構成、すなわち、捲回体の外周部分に、樹脂フィルム１１ｘの露出領域を有する構成としても構わない。 Moreover, in the said embodiment, the structure which forms the exposed area | region of the resin film 11x only as an example is demonstrated and demonstrated only in the outermost periphery part (section shown by code | symbol b-c of FIG.2 and FIG.3). However, the configuration of the present invention is not limited to this, and as shown in FIG. 4, the exposed region of the resin film 11 x is formed from a point indicated by a symbol d further inside than a point indicated by a symbol b. In other words, a configuration having an exposed region of the resin film 11x in the outer peripheral portion of the wound body may be used.
なお、上記した捲回体の「外周部分」とは、符号ａで示すポイントを起点とし、センターピン１９を捲回軸として、スパイラル状に捲回体を形成したときに、最後に巻き取られるｎ周分（ただしｎ＞１であり、符号ｄ〜ｂ〜ｃで示された区間）を指すものとする。 The “outer peripheral portion” of the wound body is wound last when the wound body is formed in a spiral shape with the point indicated by the symbol a as a starting point and the center pin 19 as a winding axis. It is intended to indicate n rounds (where n> 1 and a section indicated by symbols d to b).
また、上記実施形態では、正極１１側の樹脂フィルム１１ｘのみに露出領域を形成する構成を例に挙げて説明を行ったが、本発明の構成はこれに限定されるものではなく、図４に示すように、正極１１側の樹脂フィルム１１ｘと負極１２側の樹脂フィルム１２ｘの双方に、導電層１１ｙ、１２ｙが形成されていない露出領域を設けても構わない。 Moreover, in the said embodiment, although demonstrated taking the example of the structure which forms an exposure area | region only in the resin film 11x by the side of the positive electrode 11, the structure of this invention is not limited to this, FIG. As shown, both the resin film 11x on the positive electrode 11 side and the resin film 12x on the negative electrode 12 side may be provided with exposed regions where the conductive layers 11y and 12y are not formed.
また、上記実施形態では、樹脂フィルム１１ｘ、１２ｘの両面に、それぞれ、導電層１１ｙ、１２ｙを形成する構成を例に挙げて説明を行ったが、本発明の構成はこれに限定されるものではなく、図５に示すように、樹脂フィルム１１ｘ、１２ｘの片面にのみ、それぞれ、導電層１１ｙ、１２ｙを形成する構成としても構わない。このような構成とすることにより、捲回体を形成する際に、導電層１１ｙ、１２ｙを互いに対向させることで、両者の間に１枚のセパレータ１３を介在すれば足りることになる。 Moreover, in the said embodiment, although demonstrated taking the example of the structure which forms the conductive layers 11y and 12y on both surfaces of the resin films 11x and 12x, respectively, the structure of this invention is not limited to this. Alternatively, as shown in FIG. 5, the conductive layers 11y and 12y may be formed only on one side of the resin films 11x and 12x, respectively. With such a configuration, when forming the wound body, it is sufficient that the conductive layers 11y and 12y are opposed to each other so that one separator 13 is interposed therebetween.
また、上記実施形態では、正極１１側の樹脂フィルム１１ｘに露出領域を形成した構成を例に挙げて説明を行ったが、本発明の構成はこれに限定されるものではなく、正極１１と負極１２との関係を互いに入れ替えても構わない。すなわち、図１〜図５で示した符号１１を負極とし、符号１２を正極としてもよい。ただし、一般には、正極１１よりも負極１２の方が電極面積が大きくなるので、負極１２が捲回体の外側となることが好ましい。 Moreover, in the said embodiment, although demonstrated taking the example of the structure which formed the exposed area | region in the resin film 11x by the side of the positive electrode 11, the structure of this invention is not limited to this, The positive electrode 11 and a negative electrode 12 may be interchanged with each other. That is, reference numeral 11 shown in FIGS. 1 to 5 may be a negative electrode and reference numeral 12 may be a positive electrode. However, in general, since the electrode area of the negative electrode 12 is larger than that of the positive electrode 11, the negative electrode 12 is preferably outside the wound body.
また、上記実施形態では、円筒型の電池缶１６を用いた構成を例に挙げて説明を行ったが、本発明の構成はこれに限定されるものではなく、その他の形状（例えば、三角柱型や四角柱型）を有する電池缶１６を用いても構わない。 Moreover, in the said embodiment, although demonstrated taking the structure using the cylindrical battery can 16 as an example, the structure of this invention is not limited to this, Other shapes (for example, triangular prism type | mold) Alternatively, a battery can 16 having a quadrangular prism shape may be used.
以下では、実施例と比較例を挙げ、これらを対比することによって、本発明の作用・効果を具体的に説明するが、これらの実施例や比較例によって、本発明の技術的範囲は何ら限定されるものではない。 In the following, examples and comparative examples will be given, and the actions and effects of the present invention will be specifically described by comparing them. However, the technical scope of the present invention is not limited by these examples and comparative examples. Is not to be done.
（実施例１）
本実施例では、本発明に係る円筒型電池の充放電試験を行った。なお、正極活物質としてＬｉＣｏＯ２を１００重量部、導電材としてアセチレンブラックを１０重量部、バインダーとしてポリフッ化ビニリデン（以下ではＰＶＤＦと呼ぶ）を１０重量部、溶剤としてＮ−メチル−２−ピロリドン（以下ではＮＭＰと呼ぶ）をそれぞれ用い、正極活物質層を形成するためのペーストを作製した。また、厚さ１５［μｍ］のプロピレンフィルムの両面に厚さ１［μｍ］のアルミニウム蒸着層を形成して正極の集電体を作製した。そして、上記のペーストを集電体の両面に塗工し、十分に乾燥させた後、油圧プレスでプレスすることにより、正極を得た（樹脂フィルム幅５９［ｍｍ］×長さ７２５［ｍｍ］、電極塗工幅５９［ｍｍ］×長さ６５０［ｍｍ］）。この正極における単位面積あたりの活物質の重量は４０［ｍｇ／ｃｍ２］となった。正極の一端には、正極リードとなるアルミニウムタブを取り付けた。
Example 1
In this example, a charge / discharge test of the cylindrical battery according to the present invention was performed. In addition, 100 parts by weight of LiCoO 2 as a positive electrode active material, 10 parts by weight of acetylene black as a conductive material, 10 parts by weight of polyvinylidene fluoride (hereinafter referred to as PVDF) as a binder, and N-methyl-2-pyrrolidone (as a solvent) In the following, a paste for forming a positive electrode active material layer was prepared using NMP). Moreover, a 1 [μm] thick aluminum vapor deposition layer was formed on both sides of a 15 [μm] thick propylene film to produce a positive electrode current collector. And after apply | coating said paste on both surfaces of an electrical power collector and making it fully dry, the positive electrode was obtained by pressing with a hydraulic press (resin film width 59 [mm] x length 725 [mm] , Electrode coating width 59 [mm] × length 650 [mm]). The weight of the active material per unit area in this positive electrode was 40 [mg / cm 2 ]. An aluminum tab serving as a positive electrode lead was attached to one end of the positive electrode.
次に、負極活物質として中国産の天然黒鉛（平均粒径１５［μｍ］、平均面間隔ｄ００２＝０．３３５７［ｎｍ］、ＢＥＴ比表面積３ｍ２／ｇ）を１００重量部、バインダーとしてＰＶＤＦを１２重量部、溶剤としてＮＭＰをそれぞれ用い、負極活物質層を形成するためのペーストを作製した。また、厚さ１５［μｍ］のプロピレンフィルムの両面に厚さ１［μｍ］の銅蒸着層を形成して負極の集電体を作製した。そして、上記のペーストを集電体の両面に塗工し、十分に乾燥させた後、油圧プレスでプレスすることにより、負極を得た（樹脂フィルム幅５９［ｍｍ］×長さ７２５［ｍｍ］、電極塗工幅５９［ｍｍ］×長さ６５５［ｍｍ］）。負極の一端には、負極リードとなるニッケルタブを取り付けた。 Next, 100 parts by weight of Chinese natural graphite (average particle size 15 [μm], average interplanar spacing d002 = 0.3357 [nm], BET specific surface area 3 m 2 / g) as a negative electrode active material, and PVDF as a binder Using 12 parts by weight of NMP as a solvent, a paste for forming a negative electrode active material layer was prepared. A negative electrode current collector was prepared by forming a 1 μm thick copper vapor-deposited layer on both sides of a 15 μm thick propylene film. And after apply | coating said paste on both surfaces of an electrical power collector, and making it fully dry, the negative electrode was obtained by pressing with a hydraulic press (resin film width 59 [mm] x length 725 [mm] Electrode coating width 59 [mm] × length 655 [mm]). A nickel tab serving as a negative electrode lead was attached to one end of the negative electrode.
セパレータとしては、厚さ２５［μｍ］のポリエチレン製の微多孔膜を用いた。また、電解質としては、エチレンカーボネートとジエチルカーボネートを体積比１：１で混合した混合溶媒にリンフッ化リチウムを１Ｍの割合で溶解させた電解液を電池缶に注液した。 As the separator, a microporous film made of polyethylene having a thickness of 25 [μm] was used. Moreover, as an electrolyte, an electrolytic solution obtained by dissolving lithium phosphofluoride at a ratio of 1 M in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 was poured into a battery can.
この円筒型電池の充放電試験は、２５℃の恒温槽において、下記の表１に示す通りに実施した。さらに、特性を測定した後、満充電状態で２［ｍ］の高さからコンクリート床への落下試験を１０回行い、その電池の表面温度を観測し、落下試験後の内部短絡発生の評価を行った。 The charge / discharge test of this cylindrical battery was performed in a thermostatic bath at 25 ° C. as shown in Table 1 below. In addition, after measuring the characteristics, a drop test from a height of 2 [m] to a concrete floor is performed 10 times in a fully charged state, the surface temperature of the battery is observed, and an evaluation of internal short circuit occurrence after the drop test is performed. went.
（実施例２）
正極の集電体をアルミニウム箔（厚さ２０［μｍ］）に変更し、電極塗工領域を幅５９［ｍｍ］×長さ６６０［ｍｍ］に変更した以外は、実施例１と同様に電池を作製した。得られた電池の特性を測定した後、満充電状態で２［ｍ］の高さからコンクリート床への落下試験を１０回行い、その電池の表面温度を観測し、落下試験後の内部短絡発生の評価を行った。
(Example 2)
The battery was the same as in Example 1 except that the positive electrode current collector was changed to aluminum foil (thickness 20 [μm]) and the electrode coating area was changed to width 59 [mm] × length 660 [mm]. Was made. After measuring the characteristics of the battery obtained, the drop test from a height of 2 [m] to a concrete floor was performed 10 times in a fully charged state, the surface temperature of the battery was observed, and an internal short circuit occurred after the drop test Was evaluated.
（実施例３）
負極の集電体を銅箔（厚さ１２［μｍ］）に変更し、電極塗工領域を幅５９［ｍｍ］×長さ７２５［ｍｍ］）に変更した以外は、実施例１と同様に電池を作製した。得られた電池の特性を測定した後、満充電状態で２［ｍ］の高さからコンクリート床への落下試験を１０回行い、その電池の表面温度を観測し、落下試験後の内部短絡発生の評価を行った。
(Example 3)
Example 1 except that the negative electrode current collector was changed to copper foil (thickness 12 [μm]) and the electrode coating area was changed to width 59 [mm] × length 725 [mm]). A battery was produced. After measuring the characteristics of the battery obtained, the drop test from a height of 2 [m] to a concrete floor was performed 10 times in a fully charged state, the surface temperature of the battery was observed, and an internal short circuit occurred after the drop test Was evaluated.
（実施例４）
負極の集電体を銅箔（厚さ１２［μｍ］）に変更し、電極塗工領域を幅５９［ｍｍ］×長さ７２５［ｍｍ］）に変更し、正極のタブ接続箇所を２箇所にした以外は、実施例１と同様に電池を作製した。得られた電池の特性を測定した後、満充電状態で２［ｍ］の高さからコンクリート床への落下試験を１０回行い、その電池の表面温度を観測し、落下試験後の内部短絡発生の評価を行った。
Example 4
The negative electrode current collector was changed to copper foil (thickness 12 [μm]), the electrode coating area was changed to width 59 [mm] × length 725 [mm]), and the positive electrode tab connection locations were 2 locations. A battery was fabricated in the same manner as in Example 1 except that. After measuring the characteristics of the battery obtained, the drop test from a height of 2 [m] to a concrete floor was performed 10 times in a fully charged state, the surface temperature of the battery was observed, and an internal short circuit occurred after the drop test Was evaluated.
（比較例１）
正極の集電体をアルミニウム箔（厚さ２０［μｍ］）に、負極の集電体を銅箔（厚さ１２［μｍ］）に変更した以外は、実施例１と同様に電池を作製した。得られた電池の特性を測定した後、満充電状態で２［ｍ］の高さからコンクリート床への落下試験を１０回行い、その電池の表面温度を観測し、落下試験後の内部短絡発生の評価を行った。
(Comparative Example 1)
A battery was fabricated in the same manner as in Example 1, except that the positive electrode current collector was changed to an aluminum foil (thickness 20 [μm]) and the negative electrode current collector was changed to a copper foil (thickness 12 [μm]). . After measuring the characteristics of the battery obtained, the drop test from a height of 2 [m] to a concrete floor was performed 10 times in a fully charged state, the surface temperature of the battery was observed, and an internal short circuit occurred after the drop test Was evaluated.
上記実施例１〜４及び比較例１の電池の測定結果を下記の表２に示す。 The measurement results of the batteries of Examples 1 to 4 and Comparative Example 1 are shown in Table 2 below.
表２から、集電体に樹脂フィルムを用いた実施例１〜４の電池は、これを用いない比較例１の電池と比べて、電流特性が同程度に維持できており、落下試験後の内部短絡の発生セル数が抑制されていることが分かる。また、実施例１〜４の電池では、電池の発熱は観測されなかったが、比較例１の電池では、電池の発熱（表面温度の上昇）が観測された。 From Table 2, the batteries of Examples 1 to 4 using a resin film as a current collector can maintain the same current characteristics as the battery of Comparative Example 1 that does not use this, and after the drop test. It can be seen that the number of internal short circuit cells is suppressed. In addition, in the batteries of Examples 1 to 4, no heat generation of the battery was observed, but in the battery of Comparative Example 1, heat generation of the battery (an increase in surface temperature) was observed.
実施例１〜４及び比較例１の結果より、本発明に係るリチウムイオン二次電池１０は、安全性に優れていることが判明した。 From the results of Examples 1 to 4 and Comparative Example 1, it was found that the lithium ion secondary battery 10 according to the present invention was excellent in safety.
本発明は、捲回型の電池（例えばリチウムイオン二次電池）の安全性向上や軽量化、低コスト化を図る上で有用な技術である。 The present invention is a useful technique for improving the safety, weight reduction, and cost reduction of a wound type battery (for example, a lithium ion secondary battery).
１０ リチウムイオン二次電池
１１ 正極
１２ 負極
１３ セパレータ
１４ 正極リード
１５ 負極リード
１６ 電池缶
１７ 正極蓋
１８ 絶縁パッキン
１９ センターピン
１１ｘ、１２ｘ 樹脂フィルム
１１ｙ、１２ｙ 導電層
１１ｚ、１２ｚ 活物質層（合剤層）
DESCRIPTION OF SYMBOLS 10 Lithium ion secondary battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Positive electrode lead 15 Negative electrode lead 16 Battery can 17 Positive electrode lid 18 Insulation packing 19 Center pin 11x, 12x Resin film 11y, 12y Conductive layer 11z, 12z Active material layer (mixture layer) )
Claims (4)
前記正極及び前記負極のうち、少なくともいずれか一方は、その両面或いは片面に導電層が形成された樹脂フィルムを集電体としたものであり、かつ、
前記樹脂フィルムは、前記捲回体の外周部分に、前記導電層が一切形成されない露出領域を有することを特徴とする電池。 A battery having a wound body in which a positive electrode, a negative electrode, and a separator are integrated,
At least one of the positive electrode and the negative electrode is a current collector made of a resin film having a conductive layer formed on both sides or one side thereof, and
The battery according to claim 1, wherein the resin film has an exposed region where the conductive layer is not formed at all on an outer peripheral portion of the wound body.
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| JP5156826B2 (en) * | 2008-04-24 | 2013-03-06 | シャープ株式会社 | Non-aqueous secondary battery |
| JP2015135829A (en) * | 2010-05-20 | 2015-07-27 | エルジー・ケム・リミテッド | Cable-type secondary battery having metal-coated polymer current collector |
| JP2020198290A (en) * | 2019-05-31 | 2020-12-10 | 寧徳時代新能源科技股▲分▼有限公司Ｃｏｎｔｅｍｐｏｒａｒｙ Ａｍｐｅｒｅｘ Ｔｅｃｈｎｏｌｏｇｙ Ｃｏ．， Ｌｉｍｉｔｅｄ | Lithium ion secondary battery, cell and negative electrode sheet |
| JPWO2021192258A1 (en) * | 2020-03-27 | 2021-09-30 | ||
| WO2021192256A1 (en) * | 2020-03-27 | 2021-09-30 | Tdk株式会社 | Electrode body, electricity storage element, and electricity storage module |
| JPWO2022208625A1 (en) * | 2021-03-29 | 2022-10-06 | ||
| US11646424B2 (en) | 2019-05-31 | 2023-05-09 | Contemporary Amperex Technology Co., Limited | Lithium-ion secondary battery |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP5156826B2 (en) * | 2008-04-24 | 2013-03-06 | シャープ株式会社 | Non-aqueous secondary battery |
| JP2015135829A (en) * | 2010-05-20 | 2015-07-27 | エルジー・ケム・リミテッド | Cable-type secondary battery having metal-coated polymer current collector |
| US11611081B2 (en) | 2019-05-31 | 2023-03-21 | Contemporary Amperex Technology Co., Limited | Lithium ion secondary battery, battery core, negative electrode plate, and apparatus |
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