JP6507679B2 - Lithium ion secondary battery - Google Patents
Lithium ion secondary battery Download PDFInfo
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- JP6507679B2 JP6507679B2 JP2015015983A JP2015015983A JP6507679B2 JP 6507679 B2 JP6507679 B2 JP 6507679B2 JP 2015015983 A JP2015015983 A JP 2015015983A JP 2015015983 A JP2015015983 A JP 2015015983A JP 6507679 B2 JP6507679 B2 JP 6507679B2
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims description 37
- 229910001416 lithium ion Inorganic materials 0.000 title claims description 37
- 238000010292 electrical insulation Methods 0.000 claims description 48
- 239000000463 material Substances 0.000 claims description 18
- 150000002500 ions Chemical class 0.000 claims description 14
- 239000008151 electrolyte solution Substances 0.000 claims description 6
- 239000011148 porous material Substances 0.000 claims description 5
- 230000000052 comparative effect Effects 0.000 description 15
- 239000004743 Polypropylene Substances 0.000 description 9
- 229920001155 polypropylene Polymers 0.000 description 9
- -1 polyethylene Polymers 0.000 description 8
- 238000005259 measurement Methods 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- 229910052744 lithium Inorganic materials 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- 239000007774 positive electrode material Substances 0.000 description 4
- 239000004698 Polyethylene Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000010220 ion permeability Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 238000001035 drying Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000013032 Hydrocarbon resin Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 229920003235 aromatic polyamide Polymers 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000003411 electrode reaction Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 229920006270 hydrocarbon resin Polymers 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000002648 laminated material Substances 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000012982 microporous membrane Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920005569 poly(vinylidene fluoride-co-hexafluoropropylene) Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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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
-
- 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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- Secondary Cells (AREA)
- Cell Separators (AREA)
Description
本発明は、リチウムイオン二次電池に関する。 The present invention relates to a lithium ion secondary battery.
電池セルにおける正極および負極の正確な電位を測定する場合、参照極が必要とされている。従来技術としては、正極、負極、少なくとも２つの参照極を有する電気化学セルがある。この電気化学セルにおいては、少なくとも１つの参照極は正極面上の近傍に配置されている正極用参照極である。他の少なくとも１つの参照極は負極面上の近傍に配置されている負極用参照極である。参照極が配置される正極面上の近傍または負極面上の近傍とは、正極と負極との間の任意の位置であるとされている（特許文献１）。 When measuring the exact potential of the positive and negative electrodes in a battery cell, a reference electrode is required. Prior art includes electrochemical cells having a positive electrode, a negative electrode, and at least two reference electrodes. In this electrochemical cell, at least one reference electrode is a positive electrode reference electrode disposed in the vicinity of the positive electrode surface. The other at least one reference electrode is a negative electrode reference electrode disposed in the vicinity on the negative electrode surface. The vicinity on the positive electrode surface where the reference electrode is disposed or the vicinity on the negative electrode surface is considered to be an arbitrary position between the positive electrode and the negative electrode (Patent Document 1).
電池セルに参照極を用いる場合、正極と正極用参照極の間および負極と負極用参照極の間を電気絶縁する必要がある。このため従来技術では、正極と負極の間に複数のセパレーターを配置して、それら複数のセパレーターの間に参照極を配置している。つまり正極、セパレーター、正極用参照極、セパレーター、負極用参照極、セパレーター、負極の順に積層された構造となっている。 When using a reference electrode for a battery cell, it is necessary to electrically insulate between the positive electrode and the positive electrode reference electrode and between the negative electrode and the negative electrode reference electrode. For this reason, in the prior art, a plurality of separators are disposed between the positive electrode and the negative electrode, and a reference electrode is disposed between the plurality of separators. That is, the positive electrode, the separator, the reference electrode for the positive electrode, the separator, the reference electrode for the negative electrode, the separator, and the negative electrode are laminated in this order.
しかしながら、セパレーターはもともと充放電時において正極と負極の間に掛かる電圧を十分に電気絶縁させるために所定の電気抵抗を有している。このため正極と正極用参照極の間、および負極と負極用参照極の間の電気絶縁にセパレーターを用いると、正極と正極用参照極の間および負極と負極用参照極の間の電気抵抗が高くなる。このため正極と正極用参照極の間および負極と負極用参照極の間における電解液のイオン伝導抵抗も高くなってしまい、正極電位や負極電位の検出精度が落ちるという問題があった。 However, the separator originally has a predetermined electrical resistance in order to electrically insulate the voltage applied between the positive electrode and the negative electrode at the time of charge and discharge. Therefore, if a separator is used for electrical insulation between the positive electrode and the reference electrode for the positive electrode, and between the reference electrode for the negative electrode and the negative electrode, the electrical resistance between the positive electrode and the reference electrode for the positive electrode and between the negative electrode and the reference electrode for the negative electrode is Get higher. Therefore, the ion conduction resistance of the electrolytic solution between the positive electrode and the reference electrode for the positive electrode and between the negative electrode and the reference electrode for the negative electrode is also increased, which causes a problem that the detection accuracy of the positive electrode potential and the negative electrode potential decreases.
そこで本発明の目的は、正極および負極の正確な電位測定が可能となるリチウムイオン二次電池を提供することである。 Therefore, an object of the present invention is to provide a lithium ion secondary battery capable of accurately measuring the potential of the positive electrode and the negative electrode.
上記目的を達成するための本発明のリチウムイオン二次電池は、正極と負極とをセパレーターを介在させて対向するように配置し、電解液と共に外装材内に密封したリチウムイオン二次電池において、正極とセパレーターとの間に正極用参照極を配置し、負極とセパレーターとの間に負極用参照極を配置している。そして少なくとも正極用参照極が正極に対向する部分および少なくとも負極用参照極が負極に対向する部分には参照極電気絶縁部材を配置し、この参照極電気絶縁部材は多孔質材であり、セパレーターよりもイオン伝導抵抗が低いことを特徴とする。 The lithium ion secondary battery of the present invention for achieving the above object is a lithium ion secondary battery in which a positive electrode and a negative electrode are disposed to face each other with a separator interposed, and sealed in an outer package together with an electrolytic solution The positive electrode reference electrode is disposed between the positive electrode and the separator, and the negative electrode reference electrode is disposed between the negative electrode and the separator. A reference electrode electrical insulation member is disposed at least in a portion where the positive electrode reference electrode faces the positive electrode and at least a portion where the negative electrode reference electrode faces the negative electrode, and the reference electrode electrical insulation member is a porous material Is also characterized by low ion conduction resistance.
本発明によれば、正極と正極用参照極の間および負極と負極用参照極の間は、セパレーターに比べイオン伝導抵抗が低い参照極電気絶縁部材によってそれぞれ電気絶縁することとした。これにより、正極と正極用参照極の間、および負極と負極用参照極の間の電気抵抗が小さくなり、正極電位および負極電位を正確に測定することができる。 According to the present invention, the positive electrode and the positive electrode reference electrode and the negative electrode and the negative electrode reference electrode are electrically insulated by the reference electrode electrical insulation member having lower ion conduction resistance than the separator. As a result, the electrical resistance between the positive electrode and the positive electrode reference electrode and between the negative electrode and the negative electrode reference electrode is reduced, and the positive electrode potential and the negative electrode potential can be accurately measured.
以下、図面を参照して、本発明の実施形態を説明する。なお、図面において同一の機能を有する要素には同一の符号を付し、重複する説明を省略する。また、図面はあくまでも本発明の実施形態を説明するためのものであるので、各部材の寸法や比率は説明の都合上誇張または簡略化しており、実際の寸法や比率とは異なる。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, elements having the same function are denoted by the same reference numerals, and redundant description will be omitted. Further, since the drawings are for describing the embodiments of the present invention to the last, the dimensions and ratios of each member are exaggerated or simplified for the convenience of the description, and are different from the actual dimensions and ratios.
図１は、本実施形態によるリチウムイオン二次電池の外観を示す斜視図である。図２は本実施形態によるリチウムイオン二次電池の構成を示す分解斜視図である。 FIG. 1 is a perspective view showing the appearance of the lithium ion secondary battery according to the present embodiment. FIG. 2 is an exploded perspective view showing the configuration of the lithium ion secondary battery according to the present embodiment.
リチウムイオン二次電池１０１は、図１に示すように、電池セル（後述する正極、セパレーターおよび負極からなる）が外装材１５０によって密封された構造である。外装材１５０からは、正極タブ１０２、負極タブ１０３、正極用参照極タブ１０４、および負極用参照極タブ１０５が引き出されている。このため、このリチウムイオン二次電池１０１は、４端子構成である（４電極構成といわれることもある）。 As shown in FIG. 1, the lithium ion secondary battery 101 has a structure in which a battery cell (consisting of a positive electrode, a separator and a negative electrode described later) is sealed by an exterior material 150. The positive electrode tab 102, the negative electrode tab 103, the positive electrode reference electrode tab 104, and the negative electrode reference electrode tab 105 are drawn out from the package material 150. Therefore, the lithium ion secondary battery 101 has a four-terminal configuration (sometimes referred to as a four-electrode configuration).
リチウムイオン二次電池１０１の内部の構造は、図２に示すように、電池セル（発電要素）となる正極１０６、負極１０７、およびセパレーター１０８を有する。正極１０６とセパレーター１０８の間に正極用参照極１０９が配置されている。負極１０７とセパレーター１０８の間に負極用参照極１１０が配置されている。正極用参照極１０９は正極１０６の電位を測定するための基準電極となる。負極用参照極１１０は負極１０７の電位を測定するための基準電極となる。正極１０６は正極タブ１０２に接続されている。負極１０７は負極タブ１０３に接続されている。正極用参照極１０９と正極用参照極タブ１０４は一体物であり、外装材１５０から引き出されている部分をタブと称している。負極用参照極１１０と負極用参照極タブ１０５は一体物であり、外装材１５０から引き出されている部分をタブと称している。 The internal structure of the lithium ion secondary battery 101 has, as shown in FIG. 2, a positive electrode 106, a negative electrode 107, and a separator 108 which are battery cells (power generation elements). The positive electrode reference electrode 109 is disposed between the positive electrode 106 and the separator 108. The negative electrode reference electrode 110 is disposed between the negative electrode 107 and the separator 108. The positive electrode reference electrode 109 serves as a reference electrode for measuring the potential of the positive electrode 106. The negative electrode reference electrode 110 serves as a reference electrode for measuring the potential of the negative electrode 107. The positive electrode 106 is connected to the positive electrode tab 102. The negative electrode 107 is connected to the negative electrode tab 103. The positive electrode reference electrode 109 and the positive electrode reference electrode tab 104 are an integral body, and a portion drawn from the exterior material 150 is referred to as a tab. The negative electrode reference electrode 110 and the negative electrode reference electrode tab 105 are an integral body, and a portion drawn from the exterior material 150 is referred to as a tab.
なお、正極１０６、負極１０７、セパレーター１０８、外装材１５０、正極タブ１０２、負極タブ１０３の部材などは、通常のリチウムイオン二次電池と同様であるので、それらの詳細な説明は省略する。また、図示ないが電池セル内は電解液が充填されており、これについても通常のリチウムイオン二次電池と同様である。 The members of the positive electrode 106, the negative electrode 107, the separator 108, the package member 150, the positive electrode tab 102, the negative electrode tab 103, and the like are the same as in a normal lithium ion secondary battery, and thus detailed description thereof is omitted. Although not shown, the inside of the battery cell is filled with an electrolytic solution, which is also similar to that of a normal lithium ion secondary battery.
正極用参照極１０９および負極用参照極１１０は、それぞれその表面を参照極電気絶縁部材２１０で被覆されている。この参照極電気絶縁部材２１０によって、イオンは透過させるが電極（正極１０６、負極１０７）との間は電気絶縁している。 The surfaces of the positive electrode reference electrode 109 and the negative electrode reference electrode 110 are each covered with a reference electrode electrical insulation member 210. By means of the reference electrode electrical insulation member 210, ions are transmitted but electrical insulation is made between the electrode (positive electrode 106, negative electrode 107).
さらに参照極の構造の一例を説明する。図３は参照極の構造を説明するための説明図である。正極用参照極１０９および負極用参照極１１０は両方とも同じ構造であるので、ここでは参照極２００と称して説明する。 Further, an example of the structure of the reference electrode will be described. FIG. 3 is an explanatory view for explaining the structure of the reference electrode. Since both the positive electrode reference electrode 109 and the negative electrode reference electrode 110 have the same structure, they will be referred to as the reference electrode 200 here.
参照極２００は、参照極基材２１１の先端に参照極部２１２を接合することで形成されている。そして参照極部２１２が参照極電気絶縁部材２１０によって被覆されている。参照極基材２１１はたとえばニッケル（Ｎｉ）箔が用いられる。参照極部２１２は電位測定のための基準電極となる部分である。参照極部２１２は参照極基材２１１の先端に、たとえば金属リチウムを接合することで形成されている。参照極基材２１１はそのまま外装材１５０の外に引き出されて参照極のタブ（正極用参照極タブ１０４および負極用参照極タブ１０５）となる。 The reference electrode 200 is formed by bonding the reference electrode 212 to the tip of the reference electrode base 211. The reference electrode 212 is covered by a reference electrode electrical insulation member 210. For example, a nickel (Ni) foil is used as the reference electrode base material 211. The reference electrode portion 212 is a portion to be a reference electrode for potential measurement. The reference electrode 212 is formed by bonding metal lithium, for example, to the tip of the reference electrode base 211. The reference electrode base material 211 is drawn out of the package 150 as it is to form the tabs of the reference electrode (the reference electrode tab 104 for the positive electrode and the reference electrode tab 105 for the negative electrode).
参照極部２１２として金属リチウムを用いる場合は、参照極基材２１１の先端に金属リチウム箔を巻きつけ、参照極基材２１１ごと全体を外部からローラー等で圧力を掛けることで、参照極基材２１１と参照極部２１２とを圧着する。これにより参照極基材２１１と参照極部２１２を一体化させる。参照極基材２１１と参照極基材２１１を一体化させたのち、型抜きなどで成形してもよい。 When metallic lithium is used as the reference electrode portion 212, a metal lithium foil is wound around the tip of the reference electrode base member 211, and pressure is applied to the whole of the reference electrode base member 211 from the outside with a roller or the like. The pressure contact 211 and the reference electrode 212 are crimped. Thereby, the reference electrode base material 211 and the reference electrode part 212 are integrated. After the reference electrode base 211 and the reference electrode base 211 are integrated, they may be molded by die cutting or the like.
そして、参照極部２１２の部分を袋状の参照極電気絶縁部材２１０で被覆する。この参照極電気絶縁部材２１０は、正極用参照極１０９と正極１０６との間、および負極用参照極１１０と負極１０７との間をイオンは透過させるが電気は絶縁するものである。したがって、参照極電気絶縁部材２１０は、少なくとも正極用参照極１０９が正極１０６に対向する部分、および少なくとも負極用参照極１１０が負極１０７に対向する部分にそれぞれ配置されている必要がある。 Then, the portion of the reference electrode 212 is covered with a bag-shaped reference electrode electrical insulation member 210. The reference electrode electrical insulation member 210 transmits ions between the reference electrode 109 for the positive electrode and the positive electrode 106 and between the reference electrode 110 for the negative electrode and the negative electrode 107 but insulates electricity. Therefore, the reference electrode electrical insulation member 210 needs to be disposed at least in a portion where the positive electrode reference electrode 109 faces the positive electrode 106 and at least in a region where the negative electrode reference electrode 110 faces the negative electrode 107.
これは逆にいうと、後述する電池内部の構造から、セパレーター１０８によって電気絶縁されている面側は参照極電気絶縁部材２１０を配置しなくてもよい。正極用参照極１０９は正極１０６とセパレーター１０８との間に配置され、負極用参照極１１０は負極１０７とセパレーター１０８との間に配置されている。このため正極用参照極１０９が負極１０７と対向する部分、および負極用参照極１１０が正極１０６と対向する部分は、いずれもセパレーター１０８によって電気絶縁されている。すなわち、正極用参照極１０９においては、負極１０７と対向する部分側はセパレーター１０８が配置されているので参照極電気絶縁部材２１０はなくてもよい。同様に負極用参照極１１０においては、正極１０６と対向する部分側はセパレーター１０８が配置されているので参照極電気絶縁部材２１０はなくてもよい。 Conversely, the reference electrode electrical insulation member 210 may not be disposed on the side electrically insulated by the separator 108 because of the structure inside the battery described later. The positive electrode reference electrode 109 is disposed between the positive electrode 106 and the separator 108, and the negative electrode reference electrode 110 is disposed between the negative electrode 107 and the separator 108. Therefore, the portion where the positive electrode reference electrode 109 faces the negative electrode 107 and the portion where the negative electrode reference electrode 110 faces the positive electrode 106 are both electrically insulated by the separator 108. That is, in the reference electrode 109 for positive electrodes, since the separator 108 is disposed on the side facing the negative electrode 107, the reference electrode electrical insulation member 210 may be omitted. Similarly, in the negative electrode reference electrode 110, the separator 108 is disposed on the side opposite to the positive electrode 106, so the reference electrode electrical insulation member 210 may be omitted.
本実施形態では、図３に示したように、参照極電気絶縁部材２１０を袋状に形成することで、参照極部２１２に被せるようにしている。これにより参照極２００の製造が容易になるようにしたものである。ただし、このような袋状の参照極電気絶縁部材２１０に限定されるものではなく、たとえば参照極部２１２にフィルム状の参照極電気絶縁部材２１０を貼り付けたり、巻き付けたりするなどとしてもよい。 In the present embodiment, as shown in FIG. 3, the reference electrode portion 212 is covered by forming the reference electrode electrical insulation member 210 in a bag shape. Thereby, the manufacture of the reference electrode 200 is facilitated. However, the present invention is not limited to such a bag-like reference electrode electrical insulation member 210. For example, the film-like reference electrode electrical insulation member 210 may be attached or wound around the reference electrode portion 212.
参照極電気絶縁部材２１０は多孔質材である。多孔質材は、微多孔質（微多孔膜）を用いることが好ましい。具体的には、たとえば、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）などのポリオレフィン（また、これらを複数積層した積層体（たとえば、ＰＰ／ＰＥ／ＰＰの３層構造の積層体など））、ポリイミド、アラミド、ポリフッ化ビニリデン−ヘキサフルオロプロピレン（ＰＶｄＦ−ＨＦＰ）等の炭化水素系樹脂、さらにはガラス繊維などを挙げることができる。これらは、セパレーター１０８に用いられている材料である。さらにここに挙げた以外にも、セパレーター１０８よりもイオン伝導抵抗を低くすることのできる材料であれば使用可能である。 The reference electrode electrical insulation member 210 is a porous material. It is preferable to use a microporous (microporous membrane) as the porous material. Specifically, for example, polyolefins such as polyethylene (PE), polypropylene (PP) (also, a laminate obtained by laminating a plurality of these (eg, a laminate of a three-layer structure of PP / PE / PP, etc.)), polyimide, Examples thereof include hydrocarbon resins such as aramid and polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), and further glass fibers and the like. These are the materials used for the separator 108. Furthermore, other than those listed here, any material that can lower the ion conduction resistance than the separator 108 can be used.
電極（正極１０６および負極１０７、以下同様）の電位を精度よく測定するためには、電解液を介した状態における電極と参照極２００の間の電気抵抗を小さく抑える必要がある。この電気抵抗は、電極と参照極２００の間のイオン透過性に由来する。イオン透過性は電極と参照極２００の間の参照極電気絶縁部材２１０の厚さおよび空孔率に依存する。したがって電極と参照極２００の間の間隔が小さくなるほど単位間隔あたりのイオン透過性が高くなって、電気抵抗を抑制することができる。このため参照極電気絶縁部材２１０できるだけ薄く、また空孔率が高いほど電気抵抗を抑制することができることになる。 In order to accurately measure the potential of the electrode (positive electrode 106 and negative electrode 107, the same applies to the following), it is necessary to reduce the electrical resistance between the electrode and the reference electrode 200 in the state through the electrolytic solution. This electrical resistance is derived from the ion permeability between the electrode and the reference electrode 200. The ion permeability depends on the thickness and porosity of the reference electrode electrical insulation member 210 between the electrode and the reference electrode 200. Therefore, as the distance between the electrode and the reference electrode 200 decreases, the ion permeability per unit distance increases, and the electrical resistance can be suppressed. Therefore, as the reference electrode electrical insulation member 210 is as thin as possible and the porosity is high, the electrical resistance can be suppressed.
ところで、電池の充放電時には、正極１０６と負極１０７の間に電流が流れる。このため正極１０６と負極１０７の間に介在するセパレーター１０８は両極間に電流が流れたときに絶縁破壊しない性能を有する必要がある。このためセパレーター１０８は正極１０６と負極１０７の間に流れる電流によって絶縁破壊しないような電気抵抗を有する必要がある。そのためにセパレーター１０８は所定の厚みが必要となる。このような電気絶縁性能、また電解質保持性の観点から、セパレーター１０８は、上述した参照極電気絶縁部材２１０と同じ多孔質材を用いた場合、セパレーター１０８が乾いた状態において厚さ２５μｍ以上、空孔率５０％未満であることが好ましい。 By the way, current flows between the positive electrode 106 and the negative electrode 107 during charge and discharge of the battery. For this reason, the separator 108 interposed between the positive electrode 106 and the negative electrode 107 needs to have a performance not to cause dielectric breakdown when current flows between both electrodes. For this reason, the separator 108 needs to have an electrical resistance so as not to break down by the current flowing between the positive electrode 106 and the negative electrode 107. Therefore, the separator 108 needs to have a predetermined thickness. When the same porous material as that of the reference electrode electrical insulation member 210 described above is used from the viewpoint of such electrical insulation performance and electrolyte retention, the separator 108 has a thickness of 25 μm or more and an empty space when dried. Preferably, the porosity is less than 50%.
これに対して、正極１０６と正極用参照極１０９の間および負極１０７と負極用参照極１１０の間は、充放電時にはほとんど電流が流れない。このため正極１０６と正極用参照極１０９の間および負極１０７と負極用参照極１１０の間の電気絶縁性能は、正極負極間に配置されるセパレーター１０８より低くてもよい。このことから参照極電気絶縁部材２１０の厚みはセパレーター１０８より薄く、空孔率はセパレーター１０８より高くすることができる。 On the other hand, almost no current flows between the positive electrode 106 and the positive electrode reference electrode 109 and between the negative electrode 107 and the negative electrode reference electrode 110 during charge and discharge. Therefore, the electrical insulation performance between the positive electrode 106 and the positive electrode reference electrode 109 and between the negative electrode 107 and the negative electrode reference electrode 110 may be lower than that of the separator 108 disposed between the positive electrode and the negative electrode. From this, the thickness of the reference electrode electrical insulation member 210 can be thinner than that of the separator 108, and the porosity can be higher than that of the separator 108.
このような観点から、参照極電気絶縁部材２１０は、乾いた状態において厚さ２５μｍ未満、空孔率５５％以上であることが好ましい。これにより参照極電気絶縁部材２１０は、セパレーター１０８よりもイオン伝導抵抗を低減することができて、正極１０６と正極用参照極１０９の間および負極１０７と負極用参照極１１０の間の電気抵抗を下げることができる。 From such a viewpoint, it is preferable that the reference electrode electrical insulation member 210 has a thickness of less than 25 μm and a porosity of 55% or more in a dry state. Thereby, the reference electrode electrical insulation member 210 can reduce the ion conduction resistance more than the separator 108, and the electrical resistance between the positive electrode 106 and the positive electrode reference electrode 109 and between the negative electrode 107 and the negative electrode reference electrode 110 can be reduced. It can be lowered.
なお、参照極電気絶縁部材２１０の厚さの下限、および空孔率の上限は、正極１０６と正極用参照極１０９の間および負極１０７と負極用参照極１１０の間で絶縁破壊が起きない程度とすればよい。電気絶縁破壊が起きる限界は、実際に使用する参照極電気絶縁部材２１０の材質によって異なるため、参照極電気絶縁部材２１０の厚さの下限および空孔率の上限は特に限定されるものでない。 The lower limit of the thickness of the reference electrode electrical insulation member 210 and the upper limit of the porosity are such that dielectric breakdown does not occur between the positive electrode 106 and the positive electrode reference electrode 109 and between the negative electrode 107 and the negative electrode reference electrode 110. And it is sufficient. The lower limit of the thickness of the reference electrode electrical insulation member 210 and the upper limit of the porosity are not particularly limited because the limit at which the electrical breakdown occurs is different depending on the material of the reference electrode electrical insulation member 210 actually used.
参照極電気絶縁部材２１０は、たとえばセパレーター１０８と同じ空孔率の材料を使った場合、その厚さを薄くすることでイオン伝導抵抗を小さくしてもよい。特に、厚さを薄くすることは、電池セルとして積層方向の厚みを薄くすることができるので好ましいものである。また参照極電気絶縁部材２１０は、セパレーター１０８より空孔率を高くすることでイオン伝導抵抗を小さくしてもよい。また参照極電気絶縁部材２１０は、セパレーター１０８より薄くかつ空孔率を高くしてもよい。 For example, when using a material having the same porosity as that of the separator 108, the reference electrode electrical insulation member 210 may reduce the ion conduction resistance by reducing its thickness. In particular, reducing the thickness is preferable because the thickness in the stacking direction of the battery cell can be reduced. Further, the reference electrode electrical insulation member 210 may reduce the ion conduction resistance by making the porosity higher than that of the separator 108. The reference electrode electrical insulation member 210 may be thinner than the separator 108 and have a high porosity.
次に、リチウムイオン二次電池内部における正極用参照極１０９および負極用参照極１１０の配置について説明する。図４は図１中のＡ−Ａ線に沿う要部断面図、図５は図１中のＢ−Ｂ線に沿う要部断面図である。ただし、図４および図５において外装材１５０は省略した。また、セパレーター１０８は不定形であるが、これは電池セル内部が電解液で満たされた状態を示している。このためセパレーター１０８の一部は電解液により膨潤している状態である。 Next, the arrangement of the positive electrode reference electrode 109 and the negative electrode reference electrode 110 inside the lithium ion secondary battery will be described. 4 is a cross-sectional view of the main part along the line A-A in FIG. 1, and FIG. 5 is a cross-sectional view of the main part along the line B-B in FIG. However, the exterior material 150 was abbreviate | omitted in FIG. 4 and FIG. Further, the separator 108 is indeterminate, but this indicates that the inside of the battery cell is filled with the electrolyte. Therefore, a part of the separator 108 is in a state of being swollen by the electrolytic solution.
電池セル３００は、正極１０６、セパレーター１０８、負極１０７が積層された構造である。正極１０６は集電体３０１に正極活物質３０６が塗布されている。負極１０７は集電体３０１に負極活物質３０７が塗布されている。 The battery cell 300 has a structure in which the positive electrode 106, the separator 108, and the negative electrode 107 are stacked. In the positive electrode 106, a positive electrode active material 306 is applied to a current collector 301. In the negative electrode 107, a current collector 301 is coated with a negative electrode active material 307.
正極用参照極１０９および負極用参照極１１０は、図４に示すように、電池の１辺側に配置されている（図１参照）。正極用参照極１０９および負極用参照極１１０は、それぞれが互いに電池厚み方向（電極積層方向）で重ならないよう配置される。これにより正極用参照極１０９および負極用参照極１１０を配置したことによる電池の厚み増加を抑えることができる。 The positive electrode reference electrode 109 and the negative electrode reference electrode 110 are disposed on one side of the battery as shown in FIG. 4 (see FIG. 1). The positive electrode reference electrode 109 and the negative electrode reference electrode 110 are disposed so as not to overlap with each other in the battery thickness direction (electrode stacking direction). Thereby, the increase in thickness of the battery due to the arrangement of the positive electrode reference electrode 109 and the negative electrode reference electrode 110 can be suppressed.
また、正極用参照極１０９および負極用参照極１１０は、図５に示すように、電極端（正確には、正極活物質３０６の端部および負極活物質３０７の端部）より内側に、正極用参照極１０９および負極用参照極１１０のそれぞれの参照極部２１２部分が重なるように配置されている。 Further, as shown in FIG. 5, the reference electrode 109 for the positive electrode and the reference electrode 110 for the negative electrode are located inside the electrode end (more precisely, the end of the positive electrode active material 306 and the end of the negative electrode active material 307) The respective reference electrode portions 212 of the reference electrode 109 and the negative electrode reference electrode 110 are arranged so as to overlap each other.
これにより正極用参照極１０９および負極用参照極１１０は、電池の反応領域（正負極対向域）に存在することになって、電極反応面の電位をより精度よく捉えることができる。しかし、このような正極用参照極１０９および負極用参照極１１０の存在は、電池の充放電時に正極負極間におけるリチウムイオンの移動を阻害し、抵抗要素となってしまう虞がある。このため、電極と正極用参照極１０９および負極用参照極１１０との重なりは少ないほど好ましい。このような観点から正極用参照極１０９が正極１０６に対向する部分の重なりの長さおよび負極用参照極１１０が負極１０７に対向する部分の重なりの長さ（図中ｗ）は、たとえば１ｍｍ未満であることが好ましい（正極用参照極側がこの断面図では見えていないが負極用参照極側と同じである）。１ｍｍ未満であれば正極１０６と負極１０７の間に正極用参照極１０９および負極用参照極１１０が存在してもリチウムイオンの移動を阻害したり、抵抗要素となったりすることをきわめて少なくすることができる。 As a result, the positive electrode reference electrode 109 and the negative electrode reference electrode 110 are present in the reaction region (positive and negative electrode facing region) of the battery, and the potential on the electrode reaction surface can be captured more accurately. However, the presence of the positive electrode reference electrode 109 and the negative electrode reference electrode 110 may inhibit the movement of lithium ions between the positive electrode and the negative electrode during charge and discharge of the battery, and may be a resistive element. Therefore, it is preferable that the overlap between the electrode and the positive electrode reference electrode 109 and the negative electrode reference electrode 110 be as small as possible. From such a viewpoint, the overlapping length of the portion where the positive electrode reference electrode 109 faces the positive electrode 106 and the overlapping length (w in the figure) of the portion where the negative electrode reference electrode 110 faces the negative electrode 107 are less than 1 mm, for example. (The reference electrode side for the positive electrode is not visible in this sectional view, but is the same as the reference electrode side for the negative electrode). If it is less than 1 mm, even if the positive electrode reference electrode 109 and the negative electrode reference electrode 110 are present between the positive electrode 106 and the negative electrode 107, the movement of lithium ions is significantly reduced or the resistance element is hardly reduced. Can.
なお、重なりの長さｗの下限は、電極（正極１０６および負極１０７）の端と参照極（正極用参照極１０９および負極用参照極１１０）の端が０ｍｍとなってもよい。これは参照極電気絶縁部材２１０を介して電極から参照極にイオンが到達すれば電位測定が可能だからである。ただし、重なりが０ｍｍを超えると、すなわち電極端と参照極端が離れてしまうと、電極端と参照極端が参照極電気絶縁部材２１０の厚さよりも離れてしまうことになる。こうなると、電極と参照極との間の電気抵抗が高くなってしまうため好ましくない。 The lower limit of the overlapping length w may be 0 mm at the end of the electrode (positive electrode 106 and negative electrode 107) and the end of the reference electrode (positive electrode reference electrode 109 and negative electrode reference electrode 110). This is because if the ions reach the reference electrode from the electrode through the reference electrode electrical insulation member 210, the potential can be measured. However, if the overlap exceeds 0 mm, that is, if the electrode end and the reference extreme are separated, the electrode end and the reference extreme will be separated more than the thickness of the reference electrode electrical insulation member 210. This is not preferable because the electrical resistance between the electrode and the reference electrode is increased.
このようなリチウムイオン二次電池１０１は、上述した参照極付きの電池セル（正極１０６、セパレーター１０８、負極１０７）を外装材１５０（たとえばアルミラミネート）で覆い、内部に電解液を注液後、外装体の全辺を封止することで製造される。このような二次電池の製造工程は通常の二次電池製造工程と同様である。 Such a lithium ion secondary battery 101 covers the above-described battery cell with a reference electrode (positive electrode 106, separator 108, negative electrode 107) with an exterior material 150 (for example, aluminum laminate), and after injecting an electrolyte therein, It is manufactured by sealing all the sides of an exterior body. The manufacturing process of such a secondary battery is the same as the usual secondary battery manufacturing process.
そして、このリチウムイオン二次電池１０１は、正極用参照極タブ１０４および負極用参照極タブ１０５を通じて正極１０６、負極１０７の正確な電位測定を行うことができる。 And this lithium ion secondary battery 101 can perform exact electric potential measurement of the positive electrode 106 and the negative electrode 107 through the reference electrode tab 104 for positive electrodes, and the reference electrode tab 105 for negative electrodes.
（実施例１）
下記の通り実施例となるリチウムイオン二次電池１０１を作成した。
Example 1
A lithium ion secondary battery 101 as an example was produced as follows.
正極１０６は、集電体３０１となる厚み２０μｍのアルミニウム箔の片面に、正極活物質３０６として厚み約８０μｍのマンガン酸リチウム層を塗布後、乾燥させたものを用いた。 The positive electrode 106 was obtained by applying a lithium manganate layer having a thickness of about 80 μm as the positive electrode active material 306 on one side of an aluminum foil having a thickness of 20 μm to be the current collector 301 and drying it.
負極１０７は、集電体３０１となる厚み１０μｍの銅箔の片面に、負極活物質３０７として厚み約６０μｍのカーボン層を塗布後、乾燥させたものを用いた。 The negative electrode 107 was obtained by applying a carbon layer having a thickness of about 60 μm as the negative electrode active material 307 on one side of a copper foil having a thickness of 10 μm to be the current collector 301 and drying it.
セパレーター１０８は、ポリプロピレン製多孔質フィルム（乾いた状態において厚さ２５μｍ、空孔率５０％）を用いた。 As the separator 108, a polypropylene porous film (thickness 25 μm in a dry state, porosity 50%) was used.
正極用参照極１０９および負極用参照極１１０はともに同じ形態であり、平板状のニッケル箔の先端にリチウム箔を圧着形成し、さらに参照極電気絶縁部材２１０により参照部（リチウムの部分）を被覆して作製した。参照極電気絶縁部材２１０は、ポリプロピレン製多孔質フィルムを用いた。ポリプロピレン製多孔質フィルムは乾いた状態において厚さ１５μｍ、空孔率５５％である。 The positive electrode reference electrode 109 and the negative electrode reference electrode 110 both have the same form, and a lithium foil is formed by pressure bonding on the tip of a flat nickel foil, and the reference electrode electrical insulation member 210 further covers the reference portion (the lithium portion) Made. As the reference electrode electrical insulation member 210, a polypropylene porous film was used. The polypropylene porous film has a thickness of 15 μm and a porosity of 55% in a dry state.
図１に示たように、正極１０６、負極タブ１０３が設けられた辺とは反対側の辺に正極用参照極１０９および負極用参照極１１０を配置させた。正極用参照極１０９および負極用参照極１１０は、それぞれが互いに電池厚み方向（電極積層方向）で重ならないよう配置した。また、電極端面と正極用参照極１０９および負極用参照極１１０の重なりの長さｗは０．５ｍｍとした。 As shown in FIG. 1, the positive electrode reference electrode 109 and the negative electrode reference electrode 110 were disposed on the side opposite to the side where the positive electrode 106 and the negative electrode tab 103 were provided. The positive electrode reference electrode 109 and the negative electrode reference electrode 110 were disposed so as not to overlap with each other in the battery thickness direction (electrode stacking direction). The overlapping length w of the electrode end face, the positive electrode reference electrode 109, and the negative electrode reference electrode 110 was 0.5 mm.
これら正極１０６、セパレーター１０８、負極１０７からなる積層体をアルミラミネート材で覆い、内部に電解液を注液後に外装体開口部を全辺封止することで実施例のリチウムイオン二次電池１０１を得た。 The lithium ion secondary battery 101 of the embodiment is obtained by covering the laminate including the positive electrode 106, the separator 108, and the negative electrode 107 with an aluminum laminate material, injecting an electrolyte therein, and sealing the opening of the outer package on all sides. Obtained.
（実施例２）
実施例１において、参照極電気絶縁部材２１０として、乾いた状態において厚さ２０μｍ、空孔率７０％のポリプロピレン製多孔質フィルムを使用した。それ以外の構成は実施例１と同様である。
(Example 2)
In Example 1, a polypropylene porous film having a thickness of 20 μm and a porosity of 70% in a dry state was used as the reference electrode electrical insulation member 210. The other configuration is the same as that of the first embodiment.
（比較例）
参照極電気絶縁部材２１０に、乾いた状態において厚さ２５μｍ、空孔率５０％のポリプロピレン製多孔質フィルムを使用した以外は実施例１と同様である。
(Comparative example)
This embodiment is the same as the embodiment 1 except that a polypropylene porous film having a thickness of 25 μm and a porosity of 50% in a dry state is used for the reference electrode electrical insulation member 210.
（評価試験）
各実施例および比較例のリチウムイオン二次電池１０１を用いて充電（１Ｃ）時における正極電位および負極電位を測定した。正極電位は、正極１０６と正極用参照極１０９の間の電圧を電圧計により測定した。負極電位は、負極１０７と負極用参照極１１０の間の電圧を電圧計により測定した。測定は電池を環境温度２５℃にて行った。
(Evaluation test)
The positive electrode potential and the negative electrode potential at the time of charge (1C) were measured using the lithium ion secondary batteries 101 of each example and comparative example. The voltage between the positive electrode 106 and the reference electrode 109 for positive electrode was measured by a voltmeter. The negative electrode potential was obtained by measuring the voltage between the negative electrode 107 and the negative electrode reference electrode 110 with a voltmeter. The measurement was performed at a battery temperature of 25 ° C.
図６は各実施例および比較例のリチウムイオン二次電池を用いて測定した充電（１Ｃ）時における正極電位および負極電位の測定結果を示すグラフである（正極電位は左メモリ、負極電位は右メモリ）。図中、実施例１および２は点線、比較例は一点鎖線で示した。 FIG. 6 is a graph showing the measurement results of the positive electrode potential and the negative electrode potential during charging (1C) measured using the lithium ion secondary batteries of Examples and Comparative Examples (the positive electrode potential is for the left memory, and the negative electrode potential is for the right memory). In the figures, Examples 1 and 2 are indicated by dotted lines, and Comparative Examples are indicated by alternate long and short dashed lines.
図６から、実施例１、２および比較例のいずれも、充電の進行に伴い負極電位が低下し、正極電位が上昇しているのがわかる。 It can be seen from FIG. 6 that in any of Examples 1 and 2 and the Comparative Example, the negative electrode potential decreases with the progress of charging, and the positive electrode potential increases.
実施例１および２のリチウムイオン二次電池１０１で測定された正極電位および負極電位はほぼ同じの結果が得られた。このため図６では実施例１および２はグラフの線が重なり判別できないため、１本の点線として示した。 The positive electrode potential and the negative electrode potential measured in the lithium ion secondary battery 101 of Examples 1 and 2 obtained substantially the same results. For this reason, in FIG. 6, the lines of the graphs overlap and can not be determined in Examples 1 and 2, and therefore, they are shown as one dotted line.
これに対し、比較例のリチウムイオン二次電池１０１の結果は、正極電位は実施例１および２に対して高く、負極電位は実施例１および２に対して低い結果が得られた。 On the other hand, as a result of the lithium ion secondary battery 101 of the comparative example, the positive electrode potential was higher than those of Examples 1 and 2, and the negative electrode potential was lower than that of Examples 1 and 2.
これらの測定電位の妥当性を確認するために、それぞれのリチウムイオン二次電池１０１で測定された、セル電圧（正極負極間電圧）と、測定された正極電位と負極電位の差（正極負極電位差＝正極電位−負極電位）の比較を行った。正極電位、負極電位がともに精度よく測定されている場合、両者は一致することになる。セル電圧は正極タブ１０２と負極タブ１０３の間の電圧を電圧計により測定した。 In order to confirm the validity of these measured potentials, the difference between the cell voltage (voltage between positive electrode and negative electrode) and the measured positive electrode potential and negative electrode potential (positive electrode / negative electrode potential difference) measured in each lithium ion secondary battery 101 = Comparison of positive electrode potential-negative electrode potential) was performed. When the positive electrode potential and the negative electrode potential are both accurately measured, they will match. The cell voltage was measured with a voltmeter between the positive electrode tab 102 and the negative electrode tab 103.
図７は各実施例および比較例のリチウムイオン二次電池を充電した際のセル電圧と測定された正極負極電位差を示すグラフである。 FIG. 7 is a graph showing the cell voltage and the measured positive and negative electrode potential difference when the lithium ion secondary batteries of the respective examples and comparative examples are charged.
セル電圧は実施例１、２および比較例のいずれもほぼ同様であった。このため図中には代表的に「セル電圧」として実線で示した。正極負極電位差は実施例１および２を点線で示し（実施例１および２は同じグラフの線となって判別できないため一本の点線で示した）、比較例を一点鎖線で示した。 The cell voltage was almost the same in both Examples 1 and 2 and the Comparative Example. For this reason, in the figure, a solid line is representatively shown as "cell voltage". The positive electrode / negative electrode potential difference is shown by dotted lines in Examples 1 and 2 (indicated by one dotted line because Example 1 and 2 can not be distinguished as a line of the same graph), and a comparative example is indicated by an alternate long and short dash line.
図７から、実施例１および２は、セル電圧と正極負極電位差がほぼ一致する。これに対して比較例ではこれらが乖離（セル電圧＜正極負極電位差）している。これは、実施例１および２に対し、比較例では参照極電気絶縁部材２１０が厚く、空孔率が小さい。このため比較例では正負極と参照極２００の間のイオン伝導抵抗が相対的に大きくなり、オーム損分だけ正極１０６では電位が高く、負極１０７では電位が低く測定されたものと考えられる。 From FIG. 7, in Examples 1 and 2, the cell voltage and the positive electrode / negative electrode potential difference are almost the same. On the other hand, in the comparative example, they are separated (cell voltage <positive electrode-negative electrode potential difference). This is because the reference electrode electrical insulation member 210 is thicker and the porosity is smaller in the comparative example than in the first and second embodiments. Therefore, in the comparative example, the ion conduction resistance between the positive and negative electrodes and the reference electrode 200 is relatively large, and it is considered that the potential is high at the positive electrode 106 and low at the negative electrode 107 by the ohmic loss.
このように各実施例および比較例から、本発明を適用したリチウムイオン二次電池１０１を用いることで、電池充放電時における正極電位および負極電位を精度よく測定できることがわかる。 As described above, it is understood from Examples and Comparative Examples that by using the lithium ion secondary battery 101 to which the present invention is applied, it is possible to accurately measure the positive electrode potential and the negative electrode potential at the time of battery charge and discharge.
以上説明した実施形態および実施例による効果を説明する。 The effects of the embodiment and examples described above will be described.
（１）本実施形態および実施例によれば、正極１０６と正極用参照極１０９の間および負極１０７と負極用参照極１１０の間をセパレーター１０８に比べイオン伝導抵抗が低い参照極電気絶縁部材２１０によって電気絶縁している。このため正極１０６と正極用参照極１０９の間、および負極１０７と負極用参照極１１０の間の電気抵抗が小さくなり、正極および負極１０７の正確な電位測定が可能となる。 (1) According to the present embodiment and the examples, the reference electrode electrical insulation member 210 having a lower ion conduction resistance than the separator 108 between the positive electrode 106 and the positive electrode reference electrode 109 and between the negative electrode 107 and the negative electrode reference electrode 110 Electrically isolated by For this reason, the electrical resistance between the positive electrode 106 and the positive electrode reference electrode 109 and between the negative electrode 107 and the negative electrode reference electrode 110 is reduced, and accurate potential measurement of the positive electrode and the negative electrode 107 becomes possible.
（２）また本実施形態および実施例によれば、参照極電気絶縁部材２１０は、セパレーター１０８よりも厚さを薄くすることしたので、たとえばセパレーター１０８と同じ空孔率の材料を使っても、厚さを薄くした分、電気抵抗を小さくすることができる。 (2) Further, according to the present embodiment and the examples, since the reference electrode electrical insulation member 210 is thinner than the separator 108, for example, even if a material having the same porosity as the separator 108 is used, As the thickness is reduced, the electrical resistance can be reduced.
（３）また本実施形態および実施例によれば、参照極電気絶縁部材２１０は、セパレーター１０８より空孔率を高くすることとしたので、たとえばセパレーター１０８と同じ厚さの材料を使っても、空孔率を高くした分、電気抵抗を小さくすることができる。 (3) Further, according to the present embodiment and the examples, the reference electrode electrical insulation member 210 has a higher porosity than the separator 108. Therefore, even if a material having the same thickness as that of the separator 108 is used, for example, The electrical resistance can be reduced by increasing the porosity.
（４）また本実施形態および実施例によれば、正極用参照極１０９と負極用参照極１１０とが電池厚み方向（電極積層方向）で重ならないように配置したので、参照極の配置による電池全体の厚みの増加を抑えることができる。 (4) Further, according to the present embodiment and the examples, the positive electrode reference electrode 109 and the negative electrode reference electrode 110 are disposed so as not to overlap in the battery thickness direction (electrode stacking direction). An increase in the overall thickness can be suppressed.
（５）また本実施形態および実施例によれば、正極用参照極１０９が正極１０６に対向する部分の重なりの長さｗ、および負極用参照極１１０が負極１０７に対向する部分の重なりの長さｗを、参照極電気絶縁部材２１０の厚さを０ｍｍ以上、１ｍｍ未満にした。これにより正極負極間のイオン移動の阻害を抑制することができる。 (5) Further, according to the present embodiment and the examples, the overlapping length w of the part where the positive electrode reference electrode 109 faces the positive electrode 106 and the overlapping length of the part where the negative electrode reference electrode 110 faces the negative electrode 107 The thickness w of the reference electrode electrical insulation member 210 was set to 0 mm or more and less than 1 mm. Thereby, inhibition of ion migration between the positive and negative electrodes can be suppressed.
以上本発明を適用した実施形態について説明したが、本発明は上述した実施形態に限定されるものではない。 Although the embodiments to which the present invention is applied have been described above, the present invention is not limited to the above-described embodiments.
たとえば、上述した実施形態では、一対の正極と負極の間にセパレーターが介在した構成の二次電池を例に説明した。しかし本発明は正極、セパレーターおよび負極からなる単電池セルが、さらに複数積層されて成る積層電池にも適用することができる。この場合、積層された単電池セルのなかの任意の単電池セル部分を選択して正極用参照極、負極用参照極を配置する。これにより選択した単電池セルにおける正極電位および負極電位を測定することが可能となる。また、この場合、参照極を配置するために選択する単電池セルは複数であってもよい。 For example, in the above-described embodiment, a secondary battery having a configuration in which a separator is interposed between a pair of positive and negative electrodes has been described as an example. However, the present invention can also be applied to a laminated battery in which a plurality of unit cell consisting of a positive electrode, a separator and a negative electrode are further laminated. In this case, an optional unit cell portion of the stacked unit cells is selected to arrange the positive electrode reference electrode and the negative electrode reference electrode. This makes it possible to measure the positive electrode potential and the negative electrode potential in the selected single battery cell. Moreover, in this case, a plurality of single battery cells may be selected to arrange the reference electrode.
また実施形態では、電極タブと参照極タブが互いに対向する辺から引き出した外観構造を示したが、電極タブと参照極タブはどの辺から引き出されていてもよい。 In the embodiment, the external structure in which the electrode tab and the reference electrode tab are drawn out from the side facing each other is shown, but the electrode tab and the reference electrode tab may be drawn out from any side.
そのほか本発明は特許請求の範囲に記載された技術思想に基づいてさまざまな形態として実施可能であり、それらもまた本発明の範疇である。 Besides, the present invention can be embodied in various forms based on the technical idea described in the claims, and they are also within the scope of the present invention.
１０１ リチウムイオン二次電池、
１０２ 正極タブ、
１０３ 負極タブ、
１０４ 正極用参照極タブ、
１０５ 負極用参照極タブ、
１０６ 正極、
１０７ 負極、
１０８ セパレーター、
１０９ 正極用参照極、
１１０ 負極用参照極、
１５０ 外装材、
２００ 参照極、
２１０ 参照極電気絶縁部材、
２１１ 参照極基材、
２１２ 参照極部、
３００ 電池セル、
３０１ 集電体、
３０６ 正極活物質、
３０７ 負極活物質。
101 lithium ion secondary battery,
102 positive tab,
103 negative tab,
104 reference electrode tab for positive electrode,
105 Negative electrode reference electrode tab,
106 positive electrode,
107 negative electrode,
108 separators,
109 positive electrode reference electrode,
110 negative reference electrode,
150 exterior materials,
200 reference poles,
210 reference pole electrical insulation member,
211 reference electrode base material,
212 reference electrode,
300 battery cells,
301 current collector,
306 positive electrode active material,
307 Negative electrode active material.
Claims (5)
前記正極と前記セパレーターとの間に配置された正極用参照極と、
前記負極と前記セパレーターとの間に配置された負極用参照極と、
少なくとも前記正極用参照極が前記正極に対向する部分および少なくとも前記負極用参照極が前記負極に対向する部分にそれぞれ配置された参照極電気絶縁部材と、を有し、
前記参照極電気絶縁部材は多孔質材であり、前記セパレーターよりもイオン伝導抵抗が低いことを特徴とするリチウムイオン二次電池。 In a lithium ion secondary battery, in which a positive electrode and a negative electrode are disposed to face each other with a separator interposed, and sealed together with an electrolytic solution in an exterior material,
A positive electrode reference electrode disposed between the positive electrode and the separator;
A negative electrode reference electrode disposed between the negative electrode and the separator;
A reference electrode electrical insulation member disposed at least in a portion where the positive electrode reference electrode faces the positive electrode and at least a portion where the negative electrode reference electrode faces the negative electrode;
The lithium ion secondary battery, wherein the reference electrode electrical insulation member is a porous material and has a lower ion conduction resistance than the separator.
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