JP5809888B2 - Non-aqueous electrolyte battery - Google Patents

Non-aqueous electrolyte battery Download PDF

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JP5809888B2
JP5809888B2 JP2011192038A JP2011192038A JP5809888B2 JP 5809888 B2 JP5809888 B2 JP 5809888B2 JP 2011192038 A JP2011192038 A JP 2011192038A JP 2011192038 A JP2011192038 A JP 2011192038A JP 5809888 B2 JP5809888 B2 JP 5809888B2
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flame retardant
positive electrode
aqueous electrolyte
battery
electrolyte battery
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JP2013054891A (en
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辻川　知伸
知伸 辻川
荒川　正泰
正泰 荒川
隆之 木村
隆之 木村
傳馬　寛一
寛一 傳馬
林　晃司
晃司 林
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NTT Facilities Inc
Resonac Corp
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Shin Kobe Electric Machinery Co Ltd
NTT Facilities Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
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  • Manufacturing & Machinery (AREA)
  • Secondary Cells (AREA)
  • Cell Separators (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Description

本発明は非水電解液電池に係り、特に、活物質を含む正極合剤が集電体に塗着された正極板と、活物質を含む負極合剤が集電体に塗着された負極板とが多孔質セパレータを介して配置された非水電解液電池に関する。   The present invention relates to a nonaqueous electrolyte battery, and in particular, a positive electrode plate in which a positive electrode mixture containing an active material is applied to a current collector, and a negative electrode in which a negative electrode mixture containing an active material is applied to a current collector. The present invention relates to a non-aqueous electrolyte battery in which a plate is disposed via a porous separator.

電解液が水溶液系である二次電池としては、アルカリ蓄電池や鉛蓄電池等が知られている。これらの水溶液系二次電池に代わり、小型、軽量かつ高エネルギー密度であり、リチウム二次電池に代表される非水電解液電池が普及している。非水電解液電池に用いられる電解液には、ジメチルエーテル等の有機溶媒が含まれている。有機溶媒が可燃性を有するため、短絡等の電池異常時や火中投下時に電池温度が上昇した場合には、電池構成材料の燃焼や活物質の熱分解反応により電池挙動が激しくなるおそれがある。   Known secondary batteries whose electrolyte is an aqueous solution are alkaline storage batteries, lead storage batteries, and the like. Instead of these aqueous secondary batteries, non-aqueous electrolyte batteries typified by lithium secondary batteries, which are small, light, and have high energy density, are in widespread use. The electrolyte used for the nonaqueous electrolyte battery contains an organic solvent such as dimethyl ether. Because organic solvents are flammable, battery behavior may become severe due to combustion of battery components or thermal decomposition of active materials when battery temperature rises during battery abnormalities such as short circuits or when dropped in fire .

このような事態を回避し電池の安全性を確保するために種々の安全化技術が提案されている。例えば、非水電解液に難燃化剤（難燃性付与物質）を溶解させて非水電解液を難燃化する技術（特許文献１参照）が開示されている。また、本出願人らは、正極板、負極板あるいはセパレータに難燃化剤層を形成させる技術（特許文献２参照）を開示している。   Various safety techniques have been proposed in order to avoid such a situation and ensure the safety of the battery. For example, a technique for making a non-aqueous electrolyte incombustible by dissolving a flame retardant (a flame retardant imparting substance) in the non-aqueous electrolyte is disclosed (see Patent Document 1). Moreover, the present applicants have disclosed a technique (see Patent Document 2) for forming a flame retardant layer on a positive electrode plate, a negative electrode plate, or a separator.

特開平４−１８４８７０号公報JP-A-4-184870 ＷＯ／２０１０／１０１１８０号公報WO / 2010/101180 Publication

しかしながら、特許文献１の技術では、難燃化剤を含有させた非水電解液を難燃化させることができるものの、難燃化剤により、非水電解液電池内におけるリチウムイオンの移動抵抗が増大することが考えられる。特に、大容量非水電解液電池のように大型化するほど、難燃化剤によるリチウムイオンの移動抵抗は大きくなり、高率放電容量の低下の影響が大きく問題となる。また、特許文献２の技術では、難燃化剤層が形成された正極板、負極板あるいはセパレータ等の電池構成材料を難燃化することができるものの、リチウムイオンの移動性を考えれば、高率放電時の容量を十分に確保できるとはいえない。   However, in the technique of Patent Document 1, although the non-aqueous electrolyte containing a flame retardant can be made flame retardant, the flame retardant can reduce the movement resistance of lithium ions in the non-aqueous electrolyte battery. It is possible to increase. In particular, the larger the size of a large-capacity non-aqueous electrolyte battery, the greater the resistance of lithium ion migration due to the flame retardant, and the greater the effect of reduced high-rate discharge capacity becomes a problem. Further, in the technology of Patent Document 2, although the battery constituent material such as the positive electrode plate, the negative electrode plate, or the separator on which the flame retardant layer is formed can be made flame retardant, It cannot be said that sufficient capacity during rate discharge can be secured.

本発明は上記事案に鑑み、電池異常時の安全性を確保し高率放電時の容量低下を抑制することができる非水電解液電池を提供することを課題とする。   An object of the present invention is to provide a non-aqueous electrolyte battery capable of ensuring safety when a battery is abnormal and suppressing a decrease in capacity during high-rate discharge.

上記課題を解決するために、本発明の第１の態様は、活物質を含む正極合剤が集電体に塗着された正極板と、活物質を含む負極合剤が集電体に塗着された負極板とが多孔質セパレータを介して配置された非水電解液電池において、前記非水電解液電池の設計容量が９０Ａｈ以上であり、前記正極板の片面または両面に難燃化剤を含む難燃化剤層が配されており、前記難燃化剤の前記正極合剤に対する割合が３質量％以上８質量％以下であるとともに、前記難燃化剤層が未形成の非水電解液電池の放電容量に対する前記難燃化剤層が配された非水電解液電池の放電容量の比が５ＣＡ放電のときに８０％以上であることを特徴とする。本発明の第２の態様は、活物質を含む正極合剤が集電体に塗着された正極板と、活物質を含む負極合剤が集電体に塗着された負極板とが多孔質セパレータを介して配置された非水電解液電池において、前記非水電解液電池の設計容量が９０Ａｈ以上であり、前記正極板の片面または両面に難燃化剤のホスファゼン化合物を含む難燃化剤層が配されており、前記難燃化剤の前記正極合剤に対する割合が３質量％以上８質量％以下であるとともに、前記難燃化剤層が未形成の非水電解液電池の放電容量に対する前記難燃化剤層が配された非水電解液電池の放電容量の比が１０ＣＡ放電のときに４０％以上であることを特徴とする。 In order to solve the above-described problems, a first aspect of the present invention includes a positive electrode plate in which a positive electrode mixture containing an active material is applied to a current collector, and a negative electrode mixture containing an active material applied to the current collector. In the non-aqueous electrolyte battery in which the attached negative electrode plate is disposed via a porous separator, the design capacity of the non-aqueous electrolyte battery is 90 Ah or more, and the one or both surfaces of the positive electrode plate are flame retardant. A flame retardant layer containing an agent is disposed, and the ratio of the flame retardant to the positive electrode mixture is 3% by mass or more and 8% by mass or less, and the flame retardant layer is not formed. The ratio of the discharge capacity of the non-aqueous electrolyte battery in which the flame retardant layer is disposed to the discharge capacity of the water electrolyte battery is 80% or more at 5 CA discharge . In the second aspect of the present invention, a positive electrode plate in which a positive electrode mixture containing an active material is applied to a current collector and a negative electrode plate in which a negative electrode mixture containing an active material is applied to a current collector are porous. In the non-aqueous electrolyte battery disposed through the porous separator, the design capacity of the non-aqueous electrolyte battery is 90 Ah or more, and the one or both surfaces of the positive electrode plate include a phosphazene compound as a flame retardant Discharge of the nonaqueous electrolyte battery in which the agent layer is arranged, the ratio of the flame retardant to the positive electrode mixture is 3% by mass or more and 8% by mass or less, and the flame retardant layer is not formed. The ratio of the discharge capacity of the nonaqueous electrolyte battery in which the flame retardant layer is disposed with respect to the capacity is 40% or more when 10 CA discharge is performed.

本発明の第１、第２の態様において、難燃化剤層がリチウムイオン透過性を有することが好ましい。このとき、難燃化剤層が多孔化されていてもよい。また、難燃化剤が８０℃以下の温度環境で固体であることが好ましい。 In the first and second aspects of the present invention , the flame retardant layer preferably has lithium ion permeability. At this time, the flame retardant layer may be made porous. The flame retardant is preferably solid in a temperature environment of 80 ° C. or lower .

本発明によれば、正極板の片面または両面に難燃化剤を含む難燃化剤層を配したことで、電池異常で温度上昇したときに難燃化剤が分解するため、電池挙動を穏やかにし安全性を確保できると共に、難燃化剤の正極合剤に対する割合を３質量％以上８質量％以下とすることで、充放電時に正負極板間のリチウムイオンの移動抵抗が低減するので、設計容量が９０Ａｈ以上の非水電解液電池において、難燃化剤層が未形成の非水電解液電池の放電容量に対する難燃化剤層が配された非水電解液電池の放電容量の比が５ＣＡ放電のときに８０％以上、若しくは、１０ＣＡ放電のときに４０％以上となり高率放電時の容量低下を抑制することができる、という効果を得ることができる。 According to the present invention, by the one or both surfaces of the positive electrode plate arranged a flame retardant layer comprising a flame retardant, since the flame retardant is decomposed when the temperature increases a battery abnormality, the battery behavior As the ratio of the flame retardant to the positive electrode mixture is 3 mass% or more and 8 mass% or less, the migration resistance of lithium ions between the positive and negative electrode plates is reduced during charging and discharging. In a non-aqueous electrolyte battery having a design capacity of 90 Ah or more, the discharge capacity of the non-aqueous electrolyte battery in which the flame retardant layer is disposed relative to the discharge capacity of the non-aqueous electrolyte battery in which the flame retardant layer is not formed The ratio is 80% or more when 5 CA discharge is performed, or 40% or more when 10 CA discharge is performed, and the effect of suppressing the capacity reduction during high rate discharge can be obtained.

本発明を適用した実施形態の円筒形リチウムイオン二次電池の断面図である。It is sectional drawing of the cylindrical lithium ion secondary battery of embodiment to which this invention is applied. 実施例および比較例における設計容量４Ａｈのリチウムイオン二次電池について、正極合剤に対する難燃化剤の配合割合と、高率放電時の放電容量との関係を示すグラフである。It is a graph which shows the relationship between the mixture ratio of the flame retardant with respect to positive mix, and the discharge capacity at the time of high rate discharge about the lithium ion secondary battery of design capacity 4Ah in an Example and a comparative example. 実施例および比較例における設計容量９０Ａｈのリチウムイオン二次電池について、正極合剤に対する難燃化剤の配合割合と、高率放電時の放電容量との関係を示すグラフである。It is a graph which shows the relationship between the mixture ratio of the flame retardant with respect to positive mix, and the discharge capacity at the time of high rate discharge about the lithium ion secondary battery of the design capacity of 90Ah in an Example and a comparative example.

以下、図面を参照して、本発明を設計容量が４Ａｈの円筒形リチウムイオン二次電池に適用した実施の形態について説明する。   Hereinafter, an embodiment in which the present invention is applied to a cylindrical lithium ion secondary battery having a design capacity of 4 Ah will be described with reference to the drawings.

図１に示すように、本実施形態の円筒形リチウムイオン二次電池２０は、ニッケルメッキが施されたスチール製で有底円筒状の電池容器７を有している。電池容器７には、帯状の正負極板がセパレータを介して断面渦巻状に捲回された電極群６が収容されている。   As shown in FIG. 1, the cylindrical lithium ion secondary battery 20 of the present embodiment includes a bottomed cylindrical battery container 7 made of steel plated with nickel. The battery container 7 accommodates an electrode group 6 in which strip-like positive and negative electrode plates are wound in a spiral shape through a separator.

電極群６の捲回中心には、ポリプロピレン樹脂製で中空円筒状の軸芯１が使用されている。電極群６の上側には、軸芯１のほぼ延長線上に正極板からの電位を集電するための円環状導体の正極集電リング４が配置されている。正極集電リング４は、軸芯１の上端部に固定されている。正極集電リング４の周囲から一体に張り出している鍔部周縁には、正極板から導出された正極リード片２の端部が超音波溶接で接合されている。正極集電リング４の上方には、安全弁を内蔵し正極外部端子となる円盤状の電池蓋１１が配置されている。正極集電リング４の上部は、導体リードを介して電池蓋１１に接続されている。   A hollow cylindrical shaft core 1 made of polypropylene resin is used at the winding center of the electrode group 6. On the upper side of the electrode group 6, a positive electrode current collecting ring 4 of an annular conductor for collecting the electric potential from the positive electrode plate is disposed substantially on the extension line of the shaft core 1. The positive electrode current collecting ring 4 is fixed to the upper end portion of the shaft core 1. The edge part of the positive electrode lead piece 2 led out from the positive electrode plate is joined by ultrasonic welding to the peripheral edge of the flange part integrally protruding from the periphery of the positive electrode current collecting ring 4. Above the positive electrode current collecting ring 4, a disc-shaped battery lid 11 is provided that incorporates a safety valve and serves as a positive electrode external terminal. The upper part of the positive electrode current collecting ring 4 is connected to the battery lid 11 via a conductor lead.

一方、電極群６の下側には負極板からの電位を集電するための円環状導体の負極集電リング５が配置されている。負極集電リング５の内周面には軸芯１の下端部外周面が固定されている。負極集電リング５の外周縁には、負極板から導出された負極リード片３の端部が溶接で接合されている。負極集電リング５の下部は、導体リードを介して電池容器７の内底部に接続されている。電池容器７の寸法は、本例では、外径４０ｍｍ、内径３９ｍｍに設定されている。   On the other hand, an annular conductor negative electrode current collecting ring 5 for collecting electric potential from the negative electrode plate is disposed below the electrode group 6. The outer peripheral surface of the lower end portion of the shaft core 1 is fixed to the inner peripheral surface of the negative electrode current collecting ring 5. The end of the negative electrode lead piece 3 led out from the negative electrode plate is joined to the outer peripheral edge of the negative electrode current collecting ring 5 by welding. The lower part of the negative electrode current collection ring 5 is connected to the inner bottom part of the battery container 7 through a conductor lead. In this example, the dimensions of the battery container 7 are set to an outer diameter of 40 mm and an inner diameter of 39 mm.

電池蓋１１は、絶縁性および耐熱性のＥＰＤＭ樹脂製ガスケット１０を介して電池容器７の上部にカシメ固定されている。このため、リチウムイオン二次電池２０の内部は密封されている。また、電池容器７には、非水電解液が注液されている。非水電解液には、エチレンカーボネート（ＥＣ）とジメチルカーボネート（ＤＭＣ）とジエチルカーボネート（ＤＥＣ）との体積比１：１：１の混合溶媒中にリチウム塩として６フッ化リン酸リチウム（ＬｉＰＦ６）を１モル／リットル溶解したものが用いられている。なお、リチウムイオン二次電池２０は、所定電圧および電流で初充電を行うことで、電池機能が付与される。 The battery lid 11 is caulked and fixed to the upper part of the battery container 7 via an insulating and heat resistant EPDM resin gasket 10. For this reason, the inside of the lithium ion secondary battery 20 is sealed. In addition, a non-aqueous electrolyte is injected into the battery container 7. The non-aqueous electrolyte includes lithium hexafluorophosphate (LiPF 6) as a lithium salt in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in a volume ratio of 1: 1: 1. 1) / mol dissolved. The lithium ion secondary battery 20 is given a battery function by performing initial charging at a predetermined voltage and current.

電極群６は、正極板と負極板とが、これらの両極板が直接接触しないように、リチウムイオンが通過可能なポリエチレン製セパレータＷ５を介し、軸芯１の周囲に捲回されている。セパレータＷ５の厚さは、本例では、３０μｍに設定されている。正極リード片２と負極リード片３とが、それぞれ電極群６の互いに反対側の両端面に配置されている。下表１に示すように、電極群６の直径は、電池の設計容量によって異なり、正極板、負極板、セパレータＷ５の長さを調整することで調整される。本例では、電極群６の直径は３８ｍｍに設定されている。電極群６および正極集電リング４の鍔部周面全周には、電極群６と電池容器７との電気的接触を防止するために絶縁被覆が施されている。絶縁被覆には、ポリイミド製の基材の片面にヘキサメタアクリレートの粘着剤が塗布された粘着テープが用いられている。粘着テープは鍔部周面から電極群６の外周面に亘って一重以上巻かれている。電極群６の最大径部が絶縁被覆存在部となるように捲き数が調整され、該最大径が電池容器７の内径より僅かに小さく設定されている。   In the electrode group 6, the positive electrode plate and the negative electrode plate are wound around the shaft core 1 through a polyethylene separator W 5 through which lithium ions can pass so that the both electrode plates do not directly contact each other. In this example, the thickness of the separator W5 is set to 30 μm. The positive electrode lead piece 2 and the negative electrode lead piece 3 are arranged on both end surfaces of the electrode group 6 opposite to each other. As shown in Table 1 below, the diameter of the electrode group 6 varies depending on the design capacity of the battery, and is adjusted by adjusting the lengths of the positive electrode plate, the negative electrode plate, and the separator W5. In this example, the diameter of the electrode group 6 is set to 38 mm. Insulation coating is applied to the entire circumference of the collar peripheral surface of the electrode group 6 and the positive electrode current collecting ring 4 in order to prevent electrical contact between the electrode group 6 and the battery container 7. For the insulation coating, an adhesive tape in which a hexamethacrylate adhesive is applied to one side of a polyimide base material is used. The pressure-sensitive adhesive tape is wound one or more times from the collar surface to the outer circumferential surface of the electrode group 6. The number of windings is adjusted so that the maximum diameter portion of the electrode group 6 becomes an insulating coating existing portion, and the maximum diameter is set slightly smaller than the inner diameter of the battery container 7.

Figure 0005809888
Figure 0005809888

電極群６を構成する正極板は、正極集電体としてアルミニウム箔Ｗ１を有している。アルミニウム箔Ｗ１の厚さは、本例では、２０μｍに設定されている。アルミニウム箔Ｗ１の両面には、正極活物質としてリチウム遷移金属複合酸化物を含む正極合剤が実質的に均等かつ均質に塗着され正極合剤層Ｗ２が形成されている。すなわち、形成された正極合剤層Ｗ２の厚さがほぼ一様であり、かつ、正極合剤層Ｗ２内では正極合剤がほぼ一様に分散されている。リチウム遷移金属複合酸化物には、層状結晶構造を有するマンガンニッケルコバルト複酸リチウム粉末、スピネル結晶構造を有するマンガン酸リチウム粉末のいずれかが用いられている。正極合剤には、例えば、リチウム遷移金属複合酸化物の８５ｗｔ％に対して、導電材として鱗片状黒鉛の８ｗｔ％およびアセチレンブラックの２ｗｔ％と、バインダ（結着材）としてポリフッ化ビニリデン（以下、ＰＶＤＦと略記する。）の５ｗｔ％と、が配合されている。アルミニウム箔Ｗ１に正極合剤を塗着するときには、分散溶媒のＮ−メチル−２−ピロリドン（以下、ＮＭＰと略記する。）が用いられる。アルミニウム箔Ｗ１の長寸方向一側の側縁には、幅３０ｍｍの正極合剤の無塗着部が形成されている。無塗着部は櫛状に切り欠かれており、切り欠き残部で正極リード片２が形成されている。隣り合う正極リード片２の間隔が２０ｍｍ、正極リード片２の幅が５ｍｍに設定されている。正極板は、乾燥後プレス加工され、幅８０ｍｍに裁断されている（表１参照）。   The positive electrode plate constituting the electrode group 6 has an aluminum foil W1 as a positive electrode current collector. In this example, the thickness of the aluminum foil W1 is set to 20 μm. On both surfaces of the aluminum foil W1, a positive electrode mixture containing a lithium transition metal composite oxide as a positive electrode active material is applied substantially uniformly and uniformly to form a positive electrode mixture layer W2. That is, the thickness of the formed positive electrode mixture layer W2 is substantially uniform, and the positive electrode mixture is dispersed substantially uniformly in the positive electrode mixture layer W2. As the lithium transition metal composite oxide, either manganese nickel cobalt double acid lithium powder having a layered crystal structure or lithium manganate powder having a spinel crystal structure is used. The positive electrode mixture includes, for example, 85 wt% of the lithium transition metal composite oxide, 8 wt% of flaky graphite and 2 wt% of acetylene black as a conductive material, and polyvinylidene fluoride (hereinafter referred to as a binder). And 5 wt% of PVDF). When the positive electrode mixture is applied to the aluminum foil W1, a dispersion solvent N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) is used. An uncoated portion of a positive electrode mixture having a width of 30 mm is formed on one side edge of the aluminum foil W1 in the longitudinal direction. The non-coated portion is cut out in a comb shape, and the positive electrode lead piece 2 is formed in the remaining portion of the cutout. The interval between the adjacent positive electrode lead pieces 2 is set to 20 mm, and the width of the positive electrode lead piece 2 is set to 5 mm. The positive electrode plate is pressed after drying and cut into a width of 80 mm (see Table 1).

また、正極合剤層Ｗ２の表面、すなわち、正極板の両面には、難燃化剤を含む難燃化剤層Ｗ６が形成されている。難燃化剤層Ｗ６は、リチウムイオン透過性を有するように、造孔剤（孔形成剤）を配合することで多孔化されている。難燃化剤には、リンおよび窒素を基本骨格とするホスファゼン化合物が用いられている。難燃化剤の配合割合は、本例では、正極合剤に対して８ｗｔ％以下に設定されている。また、造孔剤には酸化アルミニウムが用いられている。酸化アルミニウムの配合割合は、難燃化剤層Ｗ６に形成する多孔の割合に合わせて調整することができる。この難燃化剤層Ｗ６は、次のようにして形成された
ものである。すなわち、ホスファゼン化合物とバインダのＰＶＤＦとを溶解させたＮＭＰ溶液に酸化アルミニウムを分散させる。得られた分散溶液を正極合剤層Ｗ２の表面に塗布し、乾燥後、プレス処理を施すことで正極板全体の厚さを調整する。 Moreover, the flame retardant layer W6 containing a flame retardant is formed on the surface of the positive electrode mixture layer W2, that is, on both surfaces of the positive electrode plate. The flame retardant layer W6 is made porous by blending a pore forming agent (pore forming agent) so as to have lithium ion permeability. As the flame retardant, a phosphazene compound having phosphorus and nitrogen as a basic skeleton is used. In this example, the blending ratio of the flame retardant is set to 8 wt% or less with respect to the positive electrode mixture. In addition, aluminum oxide is used as the pore forming agent. The mixing ratio of aluminum oxide can be adjusted according to the ratio of the porosity formed in the flame retardant layer W6. This flame retardant layer W6 is formed as follows. That is, aluminum oxide is dispersed in an NMP solution in which a phosphazene compound and a binder PVDF are dissolved. The obtained dispersion solution is applied to the surface of the positive electrode mixture layer W2, dried, and then subjected to press treatment to adjust the thickness of the entire positive electrode plate.

ホスファゼン化合物は、一般式（ＮＰＲ２）３または（ＮＰＲ２）４で表される環状化合物である。一般式中のＲは、フッ素や塩素等のハロゲン元素または一価の置換基を示している。一価の置換基としては、メトキシ基やエトキシ基等のアルコキシ基、フェノキシ基やメチルフェノキシ基等のアリールオキシ基、メチル基やエチル基等のアルキル基、フェニル基やトリル基等のアリール基、メチルアミノ基等の置換型アミノ基を含むアミノ基、メチルチオ基やエチルチオ基等のアルキルチオ基、および、フェニルチオ基等のアリールチオ基を挙げることができる。置換基の種類により固体または液体となるが、本例では、８０℃以下の温度環境で固体のホスファゼン化合物が用いられている。また、これらのホスファゼン化合物は、それぞれ所定温度で分解するものである。 The phosphazene compound is a cyclic compound represented by the general formula (NPR 2 ) 3 or (NPR 2 ) 4 . R in the general formula represents a halogen element such as fluorine or chlorine or a monovalent substituent. As monovalent substituents, alkoxy groups such as methoxy group and ethoxy group, aryloxy groups such as phenoxy group and methylphenoxy group, alkyl groups such as methyl group and ethyl group, aryl groups such as phenyl group and tolyl group, Examples thereof include an amino group containing a substituted amino group such as a methylamino group, an alkylthio group such as a methylthio group and an ethylthio group, and an arylthio group such as a phenylthio group. Depending on the type of substituent, the solid or liquid is used. In this example, a solid phosphazene compound is used in a temperature environment of 80 ° C. or lower. These phosphazene compounds are each decomposed at a predetermined temperature.

一方、負極板は、負極集電体として圧延銅箔Ｗ３を有している。圧延銅箔Ｗ３の厚さは、本例では、１０μｍに設定されている。圧延銅箔Ｗ３の両面には、負極活物質としてリチウムイオンを吸蔵、放出可能な炭素材を含む負極合剤が、正極板と同様に実質的に均等かつ均質に塗着され負極合剤層Ｗ４が形成されている。負極活物質の炭素材には、本例では、非晶質炭素粉末が用いられている。負極合剤には、例えば、非晶質炭素粉末の９０ｗｔ％に対して、バインダとしてＰＶＤＦの１０ｗｔ％が配合されている。圧延銅箔Ｗ３に負極合剤を塗着するときには、分散溶媒のＮＭＰが用いられる。圧延銅箔Ｗ３の長寸方向一側の側縁には、正極板と同様に幅３０ｍｍの負極合剤の無塗着部が形成されており、負極リード片３が形成されている。隣り合う負極リード片３の間隔が２０ｍｍ、負極リード片３の幅が５ｍｍに設定されている。負極板は、乾燥後、プレス加工され、幅８６ｍｍに裁断されている（表１参照）。なお、負極板の長さは、正極板および負極板を捲回したときに、捲回最内周および最外周で捲回方向に正極板が負極板からはみ出すことがないように、正極板の長さより１２０ｍｍ長く設定されている。また、負極合剤層Ｗ４（合剤塗布部）の幅は、捲回方向と垂直方向において正極合剤層Ｗ２が負極合剤層Ｗ４からはみ出すことがないように、正極合剤層Ｗ２の幅より６ｍｍ長く設定されている。   On the other hand, the negative electrode plate has a rolled copper foil W3 as a negative electrode current collector. In this example, the thickness of the rolled copper foil W3 is set to 10 μm. A negative electrode mixture containing a carbon material capable of occluding and releasing lithium ions as a negative electrode active material is applied to both surfaces of the rolled copper foil W3 substantially uniformly and homogeneously in the same manner as the positive electrode plate, and the negative electrode mixture layer W4. Is formed. In this example, amorphous carbon powder is used for the carbon material of the negative electrode active material. In the negative electrode mixture, for example, 10 wt% of PVDF is blended as a binder with respect to 90 wt% of the amorphous carbon powder. When applying the negative electrode mixture to the rolled copper foil W3, NMP as a dispersion solvent is used. An uncoated portion of a negative electrode mixture having a width of 30 mm is formed on the side edge on one side in the longitudinal direction of the rolled copper foil W3, and the negative electrode lead piece 3 is formed. The interval between the adjacent negative electrode lead pieces 3 is set to 20 mm, and the width of the negative electrode lead piece 3 is set to 5 mm. The negative electrode plate is dried and then pressed and cut into a width of 86 mm (see Table 1). The length of the negative electrode plate is such that when the positive electrode plate and the negative electrode plate are wound, the positive electrode plate does not protrude from the negative electrode plate in the winding direction at the innermost winding and outermost winding. 120 mm longer than the length. The width of the negative electrode mixture layer W4 (mixture application portion) is such that the positive electrode mixture layer W2 does not protrude from the negative electrode mixture layer W4 in the direction perpendicular to the winding direction. 6 mm longer.

次に、本実施形態に従い作製したリチウムイオン二次電池２０の実施例について説明する。なお、比較のために作製した比較例のリチウムイオン二次電池についても併記する。   Next, examples of the lithium ion secondary battery 20 manufactured according to the present embodiment will be described. In addition, it describes together about the lithium ion secondary battery of the comparative example produced for the comparison.

（実施例１）
実施例１では、設計容量が４Ａｈのリチウムイオン二次電池２０を作製した。すなわち、難燃化剤のホスファゼン化合物（株式会社ブリヂストン製、商品名ホスライト（登録商標）、固体状、分解温度２５０℃以上）とＰＶＤＦとを溶解させたＮＭＰ溶液に酸化アルミニウムを分散させ分散溶液を調製した。この分散溶液を正極合剤層Ｗ２の表面に塗布した。このとき、分散溶液の塗布量を調整することで、正極合剤に対する難燃化剤の配合割合を調整した。下表２に示すように、実施例１では、難燃化剤の配合割合を１ｗｔ％に調整した。また、設計容量が２０Ａｈ、５０Ａｈ、９０Ａｈのリチウムイオン二次電池２０についても、各設計容量に対応するように電極群６の直径を調整し（表１参照）、同様の手順でそれぞれ作製した。 (Example 1)
In Example 1, a lithium ion secondary battery 20 having a design capacity of 4 Ah was produced. That is, a phosphazene compound as a flame retardant (trade name Phoslite (registered trademark), manufactured by Bridgestone Corporation, solid, decomposition temperature of 250 ° C. or higher) and PVDF dissolved in an NMP solution in which aluminum oxide is dispersed to form a dispersion solution Prepared. This dispersion was applied to the surface of the positive electrode mixture layer W2. At this time, the blending ratio of the flame retardant with respect to the positive electrode mixture was adjusted by adjusting the coating amount of the dispersion solution. As shown in Table 2 below, in Example 1, the blending ratio of the flame retardant was adjusted to 1 wt%. Moreover, the diameter of the electrode group 6 was adjusted so that it corresponded to each design capacity | capacitance also about the lithium ion secondary battery 20 with a design capacity | capacitance of 20Ah, 50Ah, and 90Ah (refer Table 1), and each was produced in the same procedure.

Figure 0005809888
Figure 0005809888

（実施例２〜実施例６）
表２に示すように、実施例２〜実施例６では、難燃化剤の配合割合を変える以外は実施例１と同様にして、設計容量が４Ａｈ、２０Ａｈ、５０Ａｈ、９０Ａｈのリチウムイオン二次電池２０をそれぞれ作製した。すなわち、難燃化剤の配合割合は、実施例２では２ｗｔ％、実施例３では３ｗｔ％、実施例４では５ｗｔ％、実施例５では６ｗｔ％、実施例６では８ｗｔ％にそれぞれ調整した。 (Example 2 to Example 6)
As shown in Table 2, in Examples 2 to 6, a lithium ion secondary having a design capacity of 4 Ah, 20 Ah, 50 Ah, and 90 Ah was obtained in the same manner as in Example 1 except that the blending ratio of the flame retardant was changed. Each battery 20 was produced. That is, the blending ratio of the flame retardant was adjusted to 2 wt% in Example 2, 3 wt% in Example 3, 5 wt% in Example 4, 6 wt% in Example 5, and 8 wt% in Example 6.

（比較例１〜比較例３）
表２に示すように、比較例１では、正極合剤層の表面に難燃化剤層を形成しない以外は実施例１と同様にして、設計容量が４Ａｈ、２０Ａｈ、５０Ａｈ、９０Ａｈのリチウムイオン二次電池をそれぞれ作製した。また、比較例２および比較例３では、難燃化剤を８ｗｔ％を超える配合割合としたこと以外は実施例１と同様にして、設計容量が４Ａｈ、２０Ａｈ、５０Ａｈ、９０Ａｈのリチウムイオン二次電池をそれぞれ作製した。すなわち、難燃化剤の配合割合を、比較例２では１０ｗｔ％、比較例３では１５ｗｔ％にそれぞれ調整した。 (Comparative Examples 1 to 3)
As shown in Table 2, in Comparative Example 1, lithium ions having a design capacity of 4 Ah, 20 Ah, 50 Ah, and 90 Ah are the same as Example 1 except that the flame retardant layer is not formed on the surface of the positive electrode mixture layer. Secondary batteries were produced respectively. Moreover, in Comparative Example 2 and Comparative Example 3, the lithium ion secondary having a design capacity of 4 Ah, 20 Ah, 50 Ah, and 90 Ah was obtained in the same manner as in Example 1 except that the flame retardant was mixed in a proportion exceeding 8 wt%. Each battery was produced. That is, the blending ratio of the flame retardant was adjusted to 10 wt% in Comparative Example 2 and 15 wt% in Comparative Example 3, respectively.

（試験１）
各実施例および比較例のリチウムイオン二次電池のうち、設計容量が４Ａｈおよび９０Ａｈのリチウムイオン二次電池についてそれぞれ放電試験を行い、放電容量を評価した。放電試験は、０．２ＣＡ、５ＣＡおよび１０ＣＡの放電電流で３．０Ｖまでの放電容量を測定した。正極合剤に対する難燃化剤の割合と、比較例１のリチウムイオン二次電池の放電容量を１００％としたときの、実施例１〜６および比較例２、３の放電容量比との関係を、設計容量毎に、図２および図３のグラフにそれぞれ示す。 (Test 1)
Among the lithium ion secondary batteries of each Example and Comparative Example, discharge tests were performed on lithium ion secondary batteries with design capacities of 4 Ah and 90 Ah, and the discharge capacity was evaluated. In the discharge test, discharge capacities up to 3.0 V were measured with discharge currents of 0.2 CA, 5 CA, and 10 CA. Relationship between the ratio of the flame retardant to the positive electrode mixture and the discharge capacity ratio of Examples 1 to 6 and Comparative Examples 2 and 3 when the discharge capacity of the lithium ion secondary battery of Comparative Example 1 is 100% Are shown in the graphs of FIGS. 2 and 3 for each design capacity.

図２、図３に示すように、０．２ＣＡの放電電流で放電容量を測定した場合、難燃化剤層が形成された実施例１〜６および比較例２、３では、設計容量が４Ａｈおよび９０Ａｈのいずれについても放電容量比が９０％以上を示し、固体難燃化剤量が増加しても放電容量が維持された。これは、難燃化剤層が多孔化されて形成されたことで、充放電時にリチウムイオンが正負極板間を十分に移動でき、電池性能が確保されたためと考えられる。   As shown in FIGS. 2 and 3, when the discharge capacity was measured with a discharge current of 0.2 CA, in Examples 1 to 6 and Comparative Examples 2 and 3 in which the flame retardant layer was formed, the design capacity was 4 Ah. The discharge capacity ratio of both 90 and 90 Ah was 90% or more, and the discharge capacity was maintained even when the amount of the solid flame retardant increased. This is probably because the flame retardant layer was formed to be porous, so that lithium ions were able to move sufficiently between the positive and negative electrode plates during charge and discharge, and the battery performance was ensured.

これに対して、５ＣＡの放電電流で放電容量を測定した場合、固体難燃化剤量が８ｗｔ％以下の実施例１〜６のリチウムイオン二次電池では、設計容量が４Ａｈおよび９０Ａｈのいずれについても放電容量比が８０％以上を示したが、固体難燃化剤量が８ｗｔ％を超える比較例２、３では、放電容量比が７０％以下を示した。また、１０ＣＡの放電電流で放電容量を測定した場合、固体難燃化剤量が５ｗｔ％以下の実施例１〜４のリチウムイオン二次電池では、設計容量が４Ａｈおよび９０Ａｈのいずれについても放電容量比が８５％以上を示したが、固体難燃化剤量が６ｗｔ％以上の実施例５、６のリチウムイオン二次電池では、固体難燃化剤量が増加するにつれ放電容量比が次第に減少した。さらに、固体難燃化剤量が１０ｗｔ％以上の比較例２、３のリチウムイオン二次電池では、放電容量比が２５％以下となり、大幅に減少した。このことから、固体難燃化剤量が同じ場合、放電電流が大きいほどリチウムイオンの移動抵抗が大きくなることが判った。これは、固体難燃化剤が高率放電のような速い反応に対して正負極板間のリチウムイオンの移動抵抗となるため、放電容量比が低下したものと考えられる。   On the other hand, when the discharge capacity is measured at a discharge current of 5 CA, in the lithium ion secondary batteries of Examples 1 to 6 in which the amount of the solid flame retardant is 8 wt% or less, the design capacity is 4 Ah or 90 Ah. The discharge capacity ratio was 80% or more, but in Comparative Examples 2 and 3 where the amount of solid flame retardant exceeded 8 wt%, the discharge capacity ratio was 70% or less. In addition, when the discharge capacity was measured with a discharge current of 10 CA, in the lithium ion secondary batteries of Examples 1 to 4 in which the amount of the solid flame retardant was 5 wt% or less, the discharge capacity was 4 Ah and 90 Ah for both design capacities. The ratio was 85% or more, but in the lithium ion secondary batteries of Examples 5 and 6 in which the amount of the solid flame retardant was 6 wt% or more, the discharge capacity ratio gradually decreased as the amount of the solid flame retardant increased. did. Furthermore, in the lithium ion secondary batteries of Comparative Examples 2 and 3 in which the amount of the solid flame retardant was 10 wt% or more, the discharge capacity ratio was 25% or less, which was significantly reduced. From this, it was found that when the amount of the solid flame retardant is the same, the migration resistance of lithium ions increases as the discharge current increases. This is presumably because the solid flame retardant acts as a migration resistance of lithium ions between the positive and negative electrode plates for a fast reaction such as high rate discharge, so that the discharge capacity ratio is lowered.

また、リチウムイオン二次電池の設計容量の違いを考えると、設計容量４Ａｈのものと比較して設計容量９０Ａｈのものでは、放電電流を大きくするほど、容量低下の大きくなることが判った。さらに、設計容量２０Ａｈ、５０Ａｈのリチウムイオン二次電池についても同様の結果を示し、設計容量４Ａｈのものと９０Ａｈのものとの中間的な結果となることを確認している。従って、固体難燃化剤量を８ｗｔ％以下とすることで、設計容量が４Ａｈ以上の非水電解液電池において高率放電時の容量低下を抑制することが期待できる。   Further, considering the difference in the design capacity of the lithium ion secondary battery, it was found that the capacity decrease was greater as the discharge current was increased in the design capacity 90 Ah than in the design capacity 4 Ah. Furthermore, similar results were also shown for lithium ion secondary batteries with design capacities of 20 Ah and 50 Ah, and it was confirmed that the results were intermediate between those with design capacities of 4 Ah and those with 90 Ah. Therefore, by setting the amount of the solid flame retardant to 8 wt% or less, it can be expected that a decrease in capacity during high rate discharge is suppressed in a non-aqueous electrolyte battery having a design capacity of 4 Ah or more.

（試験２）
各実施例および比較例のリチウムイオン二次電池について、過充電試験を行い、電池表面の破裂・発火の有無を確認した。過充電試験では、電池中央部に熱電対を配置し、各リチウムイオン二次電池を０．５ＣＡの電流値で充電し続けた。過充電における破裂・発火の有無を下表３に示す。なお、表３において、矢印を表記した欄は、その上の欄と同じ結果であることを示す。 (Test 2)
About the lithium ion secondary battery of each Example and the comparative example, the overcharge test was done and the presence or absence of the burst and ignition of the battery surface was confirmed. In the overcharge test, a thermocouple was placed in the center of the battery, and each lithium ion secondary battery was continuously charged at a current value of 0.5 CA. Table 3 below shows the presence or absence of rupture / ignition during overcharge. In Table 3, the column with an arrow indicates the same result as the column above it.

Figure 0005809888
Figure 0005809888

表３に示すように、難燃化剤層が形成されていない比較例１の電池では、いずれの設計容量の電池においても、過充電試験により破裂・発火が認められた。これに対して、難燃化剤層が形成された実施例１〜６および比較例２、３の電池のうち、設計容量が４Ａｈの電池では、固体難燃化剤量が１ｗｔ％以上含まれれば、破裂・発火しないことが確認された。また、設計容量が２０Ａｈおよび５０Ａｈの電池では、固体難燃化剤量が２ｗｔ％以上、設計容量が９０Ａｈの電池では、固体難燃化剤量が３ｗｔ％以上含まれれば、破裂・発火しないことが確認された。この結果から、過充電試験における安全性を確保するためには、設計容量が大きい電池ほど固体難燃化剤量が多く必要になることが判明した。これは、設計容量の大きい電池ほど、充放電時にエネルギーが大きく、放熱性が悪化するためと考えられる。   As shown in Table 3, in the battery of Comparative Example 1 in which the flame retardant layer was not formed, rupture / ignition was observed in the battery of any design capacity by the overcharge test. On the other hand, among the batteries of Examples 1 to 6 and Comparative Examples 2 and 3 in which the flame retardant layer is formed, the battery having a design capacity of 4 Ah contains 1 wt% or more of the solid flame retardant. It was confirmed that no rupture or fire occurred. Also, batteries with a design capacity of 20 Ah and 50 Ah should not burst or ignite if the amount of solid flame retardant is 2 wt% or more, and for batteries with a design capacity of 90 Ah, if the amount of solid flame retardant is 3 wt% or more. Was confirmed. From this result, in order to ensure the safety in the overcharge test, it was found that a battery having a larger design capacity requires a larger amount of solid flame retardant. This is considered to be because a battery with a larger design capacity has a larger energy during charge / discharge, resulting in a deterioration in heat dissipation.

（作用等）
次に、本実施形態のリチウムイオン二次電池２０の作用等について説明する。 (Action etc.)
Next, the operation and the like of the lithium ion secondary battery 20 of the present embodiment will be described.

本実施形態では、電極群６を構成する正極板の正極合剤層Ｗ２の表面に、難燃化剤としてホスファゼン化合物が含有された難燃化剤層Ｗ６が形成されている。このホスファゼン化合物は、電池異常時等の高温環境下の所定温度で分解する。難燃化剤層Ｗ６が正極合剤層Ｗ２の表面に形成されることで、ホスファゼン化合物が正極活物質の近傍に存在することとなる。このため、リチウムイオン二次電池２０が異常な高温環境下に曝されたときや電池異常が生じたときに、正極活物質の熱分解反応やその連鎖反応で電池温度が上昇すると、ホスファゼン化合物が分解する。これにより、電池構成材料の燃焼が抑制されるため、リチウムイオン二次電池２０の電池挙動を穏やかにし、安全性を確保することができる。   In the present embodiment, a flame retardant layer W6 containing a phosphazene compound as a flame retardant is formed on the surface of the positive electrode mixture layer W2 of the positive electrode plate constituting the electrode group 6. This phosphazene compound decomposes at a predetermined temperature in a high temperature environment such as when the battery is abnormal. By forming the flame retardant layer W6 on the surface of the positive electrode mixture layer W2, the phosphazene compound is present in the vicinity of the positive electrode active material. For this reason, when the lithium ion secondary battery 20 is exposed to an abnormally high temperature environment or when a battery abnormality occurs, if the battery temperature rises due to the thermal decomposition reaction or chain reaction of the positive electrode active material, the phosphazene compound becomes Decompose. Thereby, since combustion of a battery constituent material is suppressed, the battery behavior of the lithium ion secondary battery 20 can be moderated and safety can be ensured.

また、本実施形態では、難燃化剤層Ｗ６に含まれる難燃化剤を正極合剤に対して８質量％以下に設定した。また、難燃化剤層Ｗ６はリチウムイオン透過性を有し、多孔化されている。このため、通常の電池使用時（充放電）時に正負極板間のリチウムイオンの移動抵抗が低減し、リチウムイオンが正負極板間を十分に移動することができる。従って、大型（設計容量が４Ａｈ以上）の非水電解液電池において、電池性能を確保することができ、高率放電時の容量低下を抑制することができる。更に、難燃化剤層Ｗ６が正極合剤層Ｗ２の表面に形成されているため、正極合剤層Ｗ２では、電極反応を生じさせる正極活物質の配合割合が確保されるので、リチウムイオン二次電池２０の容量や出力を確保することができる。   Moreover, in this embodiment, the flame retardant contained in the flame retardant layer W6 was set to 8 mass% or less with respect to the positive electrode mixture. The flame retardant layer W6 has lithium ion permeability and is made porous. For this reason, the movement resistance of lithium ions between the positive and negative electrode plates is reduced during normal battery use (charging and discharging), and lithium ions can sufficiently move between the positive and negative electrode plates. Therefore, in a large-sized (design capacity is 4 Ah or more) non-aqueous electrolyte battery, battery performance can be ensured, and capacity reduction during high rate discharge can be suppressed. Furthermore, since the flame retardant layer W6 is formed on the surface of the positive electrode mixture layer W2, the positive electrode mixture layer W2 ensures a blending ratio of the positive electrode active material that causes an electrode reaction. The capacity and output of the secondary battery 20 can be ensured.

更に、本実施形態では、難燃化剤として８０℃以下の温度環境で固体のホスファゼン化合物が用いられている。このため、通常の電池使用時にはホスファゼン化合物が固体の状態で難燃化剤層Ｗ６として保持され、非水電解液中に溶出することがないので、リチウムイオン二次電池２０の電池性能を確保することができる。   Furthermore, in this embodiment, a solid phosphazene compound is used as a flame retardant in a temperature environment of 80 ° C. or lower. For this reason, since the phosphazene compound is held as a flame retardant layer W6 in a solid state and is not eluted in the non-aqueous electrolyte during normal battery use, the battery performance of the lithium ion secondary battery 20 is ensured. be able to.

なお、本実施形態では、設計容量が４Ａｈ、２０Ａｈ、５０Ａｈ、９０Ａｈのリチウムイオン二次電池２０をそれぞれ例示したが、本発明はこれに限定されるものではない。例えば、設計容量が９０Ａｈを超える電池において、過充電試験における安全性を確保することを考慮すれば難燃化剤の配合割合が３ｗｔ％以上に制限されるものの、難燃化剤の配合割合を８ｗｔ％以下とすることで、高率放電時の容量低下を抑制することが期待できる。   In the present embodiment, the lithium ion secondary batteries 20 having design capacities of 4 Ah, 20 Ah, 50 Ah, and 90 Ah are exemplified, but the present invention is not limited to this. For example, in a battery having a design capacity exceeding 90 Ah, the flame retardant compounding ratio is limited to 3 wt% or more in consideration of ensuring safety in the overcharge test. By setting the content to 8 wt% or less, it can be expected to suppress the capacity decrease during high rate discharge.

また、本実施形態では、正極合剤層Ｗ２の表面、すなわち、正極板の両面に難燃化剤層Ｗ６を形成する例を示したが、本発明はこれに限定されるものではない。例えば、負極板やセパレータＷ５に形成するようにしてもよい。すなわち、難燃化剤層Ｗ６が、正極板、負極板およびセパレータＷ５の少なくとも１つの片面または両面に形成されていればよい。更に、本実施形態では、バインダとしてＰＶＤＦを用いて難燃化剤層Ｗ６を形成させる例を示したが、本発明はこれに限定されるものではなく、難燃化剤層Ｗ６を形成可能であればいかなるバインダを用いてもよい。   In the present embodiment, an example in which the flame retardant layer W6 is formed on the surface of the positive electrode mixture layer W2, that is, both surfaces of the positive electrode plate is shown, but the present invention is not limited to this. For example, you may make it form in a negative electrode plate or the separator W5. That is, the flame retardant layer W6 only needs to be formed on at least one side or both sides of the positive electrode plate, the negative electrode plate, and the separator W5. Furthermore, in this embodiment, although the example which forms the flame retardant layer W6 using PVDF as a binder was shown, this invention is not limited to this, The flame retardant layer W6 can be formed. Any binder can be used.

更に、本実施形態では、難燃化剤層Ｗ６の形成時に、造孔剤として酸化アルミニウムを配合する例を示したが、本発明は、用いる造孔剤に制限されるものではない。また、本実施形態では、難燃化剤層Ｗ６が多孔化されている例を示したが、本発明はこれに限定されるものではなく、通常の充放電時にリチウムイオンが通過可能であれば、難燃化剤層Ｗ６が多孔化されていなくてもよい。   Furthermore, in this embodiment, the example which mix | blends an aluminum oxide as a pore making agent was shown at the time of formation of the flame retardant layer W6, However, This invention is not restrict | limited to the pore forming agent to be used. Moreover, in this embodiment, although the example in which the flame retardant layer W6 is made porous is shown, the present invention is not limited to this, and lithium ions can pass during normal charge / discharge. The flame retardant layer W6 may not be made porous.

また更に、本実施形態では、難燃化剤層Ｗ６に含まれる難燃化剤の正極合剤に対する割合を１ｗｔ％以上に設定する例を示した（実施例１〜実施例６）。難燃化剤の配合割合が１ｗｔ％に満たないと熱分解反応による温度上昇を抑制することが難しくなり、反対に、難燃化剤の配合割合が８ｗｔ％超えると、リチウムイオン移動抵抗が大きくなり、高率放電時の容量や出力を低下させることとなる。難燃化剤の配合割合が増加するほど、高率放電時の容量が低下することを考慮すれば、難燃化剤の配合割合を１〜８ｗｔ％の範囲とすることが好ましい。また、過充電時における安全性の確保を考慮すれば、設計容量が２０Ａｈ以上の電池では固体難燃化剤量が２ｗｔ％以上、設計容量が９０Ａｈ以上の電池では固体難燃化剤量が３ｗｔ％以上含まれることが好ましい。   Furthermore, in this embodiment, the example which sets the ratio with respect to the positive mix of the flame retardant contained in the flame retardant layer W6 to 1 wt% or more was shown (Example 1-Example 6). If the blending ratio of the flame retardant is less than 1 wt%, it is difficult to suppress the temperature rise due to the thermal decomposition reaction. Conversely, if the blending ratio of the flame retardant exceeds 8 wt%, the lithium ion transfer resistance is large. Thus, the capacity and output during high rate discharge are reduced. Considering that the capacity during high rate discharge decreases as the blending ratio of the flame retardant increases, the blending ratio of the flame retardant is preferably in the range of 1 to 8 wt%. In addition, in consideration of ensuring safety during overcharge, the amount of solid flame retardant is 2 wt% or more for a battery with a design capacity of 20 Ah or more, and the amount of solid flame retardant is 3 wt for a battery with a design capacity of 90 Ah or more. % Or more is preferable.

更にまた、本実施形態では、難燃化剤としてホスファゼン化合物を例示したが、本発明はこれに限定されるものではなく、所定温度で分解し活物質の熱分解反応やその連鎖反応による温度上昇を抑制することができるものであればよい。また、ホスファゼン化合物についても本実施形態で例示した化合物以外の化合物を用いることも可能である。   Furthermore, in the present embodiment, the phosphazene compound is exemplified as the flame retardant, but the present invention is not limited to this, and the temperature is increased by decomposition at a predetermined temperature and thermal decomposition reaction of the active material or its chain reaction. What is necessary is just to be able to suppress this. Moreover, it is also possible to use compounds other than the compound illustrated by this embodiment also about a phosphazene compound.

また、本実施形態では、設計容量が４Ａｈの円筒形リチウムイオン二次電池２０を例示したが、本発明はこれに限定されるものではなく、電池容量が４Ａｈを超える大型のリチウムイオン二次電池に適用することができる。また、本実施形態では、正極板、負極板を捲回した電極群６を例示したが、本発明はこれに限定されるものではなく、例えば、矩形状の正極板、負極板を積層した電極群としてもよい。更に、電池形状についても、円筒形以外に角型等としてもよいことはもちろんである。また、正極活物質や負極活物質の種類、非水電解液の組成等についても特に制限されるものではない。   In the present embodiment, the cylindrical lithium ion secondary battery 20 having a design capacity of 4 Ah is exemplified. However, the present invention is not limited to this, and a large lithium ion secondary battery having a battery capacity exceeding 4 Ah. Can be applied to. Moreover, in this embodiment, although the electrode group 6 which wound the positive electrode plate and the negative electrode plate was illustrated, this invention is not limited to this, For example, the electrode which laminated | stacked the rectangular positive electrode plate and the negative electrode plate It is good also as a group. Furthermore, the battery shape may be a square shape in addition to the cylindrical shape. Further, the type of the positive electrode active material and the negative electrode active material, the composition of the non-aqueous electrolyte, and the like are not particularly limited.

更に、本実施形態では、有底円筒状の電池容器７を用いたリチウムイオン二次電池２０を例示したが、本発明はこれに限定されるものではなく、無底円筒状の電池容器を用いてもよい。電池容器に無底円筒状のものを用いた場合、２つの開口を２つの蓋体で封止すればよい。このとき、２つの蓋体の中心に穴を形成し、正極外部端子および負極外部端子を構成する２本の極柱をそれぞれ２つの蓋体の穴に嵌め込み軸芯に挿入してもよい。   Further, in the present embodiment, the lithium ion secondary battery 20 using the bottomed cylindrical battery container 7 is illustrated, but the present invention is not limited to this, and a bottomless cylindrical battery container is used. May be. When a bottomless cylindrical container is used for the battery container, the two openings may be sealed with two lids. At this time, a hole may be formed at the center of the two lids, and the two pole columns constituting the positive electrode external terminal and the negative electrode external terminal may be fitted into the holes of the two lids and inserted into the shaft core.

また更に、本実施形態では、正極活物質に、層状結晶構造を有するマンガンニッケルコバルト複酸リチウム粉末、スピネル結晶構造を有するマンガン酸リチウム粉末のいずれかを用いる例を示したが、本発明で用いることのできる正極活物質としてはリチウム遷移金属複合酸化物であればよい。また、本発明はリチウムイオン二次電池に制限されるものではなく、非水電解液を用いた非水電解液電池に適用できることはいうまでもない。   Furthermore, in the present embodiment, an example in which either a manganese nickel cobalt lithium double acid powder having a layered crystal structure or a lithium manganate powder having a spinel crystal structure is used as the positive electrode active material has been described. The positive electrode active material that can be used may be a lithium transition metal composite oxide. Further, the present invention is not limited to the lithium ion secondary battery, and it goes without saying that the present invention can be applied to a nonaqueous electrolyte battery using a nonaqueous electrolyte.

本発明は電池異常時の安全性を確保し高率放電時の容量低下を抑制することができる非水電解液電池を提供するため、非水電解液電池の製造、販売に寄与するので、産業上の利用可能性を有する。   Since the present invention contributes to the manufacture and sale of non-aqueous electrolyte batteries in order to provide a non-aqueous electrolyte battery that can ensure safety in the event of battery abnormalities and suppress capacity reduction during high rate discharge, With the above applicability.

Ｗ１ アルミニウム箔（集電体）
Ｗ２ 正極合剤層
Ｗ３ 圧延銅箔（集電体）
Ｗ４ 負極合剤層
Ｗ５ セパレータ
Ｗ６ 難燃化剤層
６ 電極群
２０ 円筒形リチウムイオン二次電池（非水電解液電池） W1 Aluminum foil (current collector)
W2 Positive electrode mixture layer W3 Rolled copper foil (current collector)
W4 Negative electrode mixture layer W5 Separator W6 Flame retardant layer 6 Electrode group 20 Cylindrical lithium ion secondary battery (non-aqueous electrolyte battery)

Claims (5)

活物質を含む正極合剤が集電体に塗着された正極板と、活物質を含む負極合剤が集電体に塗着された負極板とが多孔質セパレータを介して配置された非水電解液電池において、前記非水電解液電池の設計容量が９０Ａｈ以上であり、前記正極板の片面または両面に難燃化剤のホスファゼン化合物を含む難燃化剤層が配されており、前記難燃化剤の前記正極合剤に対する割合が３質量％以上８質量％以下であるとともに、前記難燃化剤層が未形成の非水電解液電池の放電容量に対する前記難燃化剤層が配された非水電解液電池の放電容量の比が５ＣＡ放電のときに８０％以上であることを特徴とする非水電解液電池。 A positive electrode plate in which a positive electrode mixture containing an active material is applied to a current collector and a negative electrode plate in which a negative electrode mixture containing an active material is applied to a current collector are arranged via a porous separator. In the water electrolyte battery, the non-aqueous electrolyte battery has a design capacity of 90 Ah or more, and a flame retardant layer containing a phosphazene compound as a flame retardant is disposed on one side or both sides of the positive electrode plate , The ratio of the flame retardant to the positive electrode mixture is 3% by mass or more and 8% by mass or less, and the flame retardant layer with respect to the discharge capacity of the non-aqueous electrolyte battery in which the flame retardant layer is not formed. The non-aqueous electrolyte battery is characterized in that the ratio of the discharge capacity of the non-aqueous electrolyte battery in which is disposed is 80% or more when 5 CA discharge occurs . 活物質を含む正極合剤が集電体に塗着された正極板と、活物質を含む負極合剤が集電体に塗着された負極板とが多孔質セパレータを介して配置された非水電解液電池において、前記非水電解液電池の設計容量が９０Ａｈ以上であり、前記正極板の片面または両面に難燃化剤のホスファゼン化合物を含む難燃化剤層が配されており、前記難燃化剤の前記正極合剤に対する割合が３質量％以上８質量％以下であるとともに、前記難燃化剤層が未形成の非水電解液電池の放電容量に対する前記難燃化剤層が配された非水電解液電池の放電容量の比が１０ＣＡ放電のときに４０％以上であることを特徴とする非水電解液電池。A positive electrode plate in which a positive electrode mixture containing an active material is applied to a current collector and a negative electrode plate in which a negative electrode mixture containing an active material is applied to a current collector are arranged via a porous separator. In the water electrolyte battery, the non-aqueous electrolyte battery has a design capacity of 90 Ah or more, and a flame retardant layer containing a phosphazene compound as a flame retardant is disposed on one side or both sides of the positive electrode plate, The ratio of the flame retardant to the positive electrode mixture is 3% by mass or more and 8% by mass or less, and the flame retardant layer with respect to the discharge capacity of the non-aqueous electrolyte battery in which the flame retardant layer is not formed is A non-aqueous electrolyte battery characterized in that the ratio of the discharge capacity of the arranged non-aqueous electrolyte battery is 40% or more at 10 CA discharge. 前記難燃化剤層はリチウムイオン透過性を有することを特徴とする請求項１または請求項２に記載の非水電解液電池。 Non-aqueous electrolyte battery according to claim 1 or claim 2 wherein the flame retardant layer is characterized by having lithium ion permeability. 前記難燃化剤層は多孔化されていることを特徴とする請求項３に記載の非水電解液電池。 The non-aqueous electrolyte battery according to claim 3 , wherein the flame retardant layer is porous. 前記難燃化剤は８０℃以下の温度環境で固体であることを特徴とする請求項１または請求項２に記載の非水電解液電池。 Non-aqueous electrolyte battery according to claim 1 or claim 2, wherein the flame retardant is solid at 80 ° C. below the temperature environment.
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