JP6146231B2 - Secondary battery - Google Patents

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JP6146231B2
JP6146231B2 JP2013195256A JP2013195256A JP6146231B2 JP 6146231 B2 JP6146231 B2 JP 6146231B2 JP 2013195256 A JP2013195256 A JP 2013195256A JP 2013195256 A JP2013195256 A JP 2013195256A JP 6146231 B2 JP6146231 B2 JP 6146231B2
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positive electrode
active material
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electrode active
insulating layer
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JP2015060787A (en
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晃一 谷山
晃一 谷山
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Mitsubishi Motors Corp
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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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Description

本発明は、セパレータを挿んで交互に配置される正極板と負極板との端部の間で短絡することを防止する構造を有した二次電池に関する。   The present invention relates to a secondary battery having a structure that prevents a short circuit between end portions of a positive electrode plate and a negative electrode plate that are alternately arranged with a separator interposed therebetween.

リチウムイオン電池などの二次電池は、セパレータを間に挟んで正極板と負極板とを交互に配置したコアを有している。短いシート状の正極板と負極板とをセパレータを介して厚み方向に繰り返し重ねた積層型のコアと、セパレータを挿んで長い帯状の正極板と負極板とを巻き重ねた捲回型のコアとが知られている。正極板は、基材となるアルミニウム箔に正極活物質が塗布された正極活物質合剤層を両面に有し、一方の縁にアルミニウム箔が露出した正極リードを備えている。負極板は、基材となる銅箔に負極活物質が塗布された負極活物質合剤層を両面に有し、他方の縁に銅箔が露出した負極リードを備えている。   A secondary battery such as a lithium ion battery has a core in which a positive electrode plate and a negative electrode plate are alternately arranged with a separator interposed therebetween. A laminated core in which a short sheet-like positive electrode plate and a negative electrode plate are repeatedly stacked in the thickness direction through a separator, and a wound core in which a long strip-shaped positive electrode plate and a negative electrode plate are wound with the separator interposed therebetween, It has been known. The positive electrode plate has a positive electrode active material mixture layer in which a positive electrode active material is applied to an aluminum foil serving as a base material on both sides, and includes a positive electrode lead in which the aluminum foil is exposed on one edge. The negative electrode plate has a negative electrode active material mixture layer in which a negative electrode active material is applied to a copper foil serving as a base material on both sides, and a negative electrode lead in which the copper foil is exposed on the other edge.

正極リードおよび負極リードは、正極板と負極板との間に配置されるセパレータの両縁から互いに反対側に張り出すように配置される。このとき、負極活物質合剤層の塗布領域の幅に比べて正極活物質合剤層の塗布領域の幅のほうが狭いため、負極活物質合剤層と正極リードとが対向する範囲において、短絡しないような配慮が必要である。   The positive electrode lead and the negative electrode lead are arranged so as to protrude from both edges of the separator arranged between the positive electrode plate and the negative electrode plate to the opposite sides. At this time, since the width of the application region of the positive electrode active material mixture layer is narrower than the width of the application region of the negative electrode active material mixture layer, a short circuit occurs in a range where the negative electrode active material mixture layer and the positive electrode lead face each other. Consideration not to be necessary is necessary.

電極間が短絡する要因は、製造工程で生じる電極の断片など導電性の異物であると想定される。これらの異物は、電極間に直接触れて短絡させるだけでなく、電解液に溶解してイオン化したのち負極側で還元されて析出し、デンドライトを形成することによっても短絡を引き起こすと考えられる。   The cause of a short circuit between the electrodes is assumed to be conductive foreign matter such as electrode fragments generated in the manufacturing process. These foreign substances are not only directly touched between the electrodes to cause a short circuit, but are also dissolved and ionized in the electrolytic solution, and then reduced and deposited on the negative electrode side to form a dendrite.

特許文献１に記載された角型リチウムイオン二次電池は、捲回型の捲回電極群（コア）を有している。正極板は、正極リードと正極活物質合剤層との境界に絶縁層を有している。この絶縁層は、正極活物質合剤層の側縁に重なるように、かつ正極活物質合剤層と同じ厚みに形成されている。絶縁層とセパレータとで正極リードの基部を覆うことで、負極活物質合剤層と正極リードとが触れないようにしている。   The prismatic lithium ion secondary battery described in Patent Document 1 has a wound type wound electrode group (core). The positive electrode plate has an insulating layer at the boundary between the positive electrode lead and the positive electrode active material mixture layer. This insulating layer is formed to have the same thickness as the positive electrode active material mixture layer so as to overlap the side edge of the positive electrode active material mixture layer. The base portion of the positive electrode lead is covered with the insulating layer and the separator so that the negative electrode active material mixture layer and the positive electrode lead are not touched.

特開２０１１−２１６４０３号公報JP 2011-216403 A

ところで、リチウムイオン電池のような二次電池は、製造直後の充放電において、電極の周囲にわずかながらにガスを発生する。これらのガスは、電極の間に残留すると電池の性能を低下させるだけでなく、電池の容器を膨らませるなど変形させる要因となるため、排出されることが望ましい。特許文献１に開示されたリチウムイオン電池の場合、正極活物質合剤層と同じ厚みに絶縁層を形成している。この絶縁層は、セパレータとともに正極リードの基部を周囲から隔絶するように覆い隠している。特許文献１における絶縁層は、ホットメルトコーティング方式によって熱可塑性の絶縁性樹脂を塗布することで形成される。そのため、発生したガスは、絶縁層を通して排出しにくい。   By the way, a secondary battery such as a lithium ion battery generates a slight amount of gas around the electrode during charge and discharge immediately after manufacture. If these gases remain between the electrodes, they not only deteriorate the performance of the battery, but also cause deformation such as inflating the battery container, so that it is desirable to discharge these gases. In the case of the lithium ion battery disclosed in Patent Document 1, the insulating layer is formed in the same thickness as the positive electrode active material mixture layer. The insulating layer covers the base of the positive electrode lead together with the separator so as to isolate it from the surroundings. The insulating layer in Patent Document 1 is formed by applying a thermoplastic insulating resin by a hot melt coating method. Therefore, the generated gas is difficult to exhaust through the insulating layer.

また、負極板の負極リードを集電板に溶接する際に生じるスパッタなどによって正極板と負極板とが短絡することを防止するために、正極板の正極リードと反対側の縁に正極合剤層と同じ厚さの耐熱絶縁層を設けることも知られている。この耐熱絶縁層は、セラミック系の材料が採用され、正極合剤層の空隙率よりも大きい空隙率に形成される。しかしながら、絶縁層の空隙率が正極合剤層の空隙率よりも大きいということは、電解液中に溶解したイオンが正極合剤層と同様に通過することを意味している。つまり、絶縁層が空隙率を有した部材で形成されていると、空隙にデンドライトが析出することで、正極と負極とが短絡する。   In addition, in order to prevent the positive electrode plate and the negative electrode plate from being short-circuited by sputtering or the like generated when the negative electrode lead of the negative electrode plate is welded to the current collector plate, the positive electrode mixture is formed on the edge of the positive electrode plate opposite to the positive electrode lead. It is also known to provide a heat resistant insulating layer with the same thickness as the layer. This heat-resistant insulating layer is made of a ceramic material and is formed with a porosity larger than the porosity of the positive electrode mixture layer. However, the fact that the porosity of the insulating layer is larger than the porosity of the positive electrode mixture layer means that ions dissolved in the electrolytic solution pass in the same manner as the positive electrode mixture layer. That is, when the insulating layer is formed of a member having a porosity, dendrites are deposited in the voids, so that the positive electrode and the negative electrode are short-circuited.

さらに、上述のこれらのリチウムイオン電池において、絶縁層は、いずれも正極活物質合剤層（正極合剤）の縁を覆っている。正極活物質合剤層の縁が覆われることによって、正極からリチウムイオンを供給するための有効な表面積が減少することになるため、発電効率及び充電効率が低下する。   Furthermore, in these lithium ion batteries described above, the insulating layer covers the edge of the positive electrode active material mixture layer (positive electrode mixture). When the edge of the positive electrode active material mixture layer is covered, the effective surface area for supplying lithium ions from the positive electrode is reduced, so that power generation efficiency and charging efficiency are reduced.

そこで、本発明は、電極間が短絡することを簡単な構造で防止し、かつ電極に発生するガスを排出しやすい二次電池を提供する。   Therefore, the present invention provides a secondary battery that prevents a short circuit between electrodes with a simple structure and easily discharges gas generated in the electrodes.

本発明に係る一実施形態の二次電池は、第１の辺とこの対辺の第２の辺とを有するセパレータを間に挟んで正極及び負極を交互に積層した構造のコアを備える。そして、正極は、正極集電体と、正極活物質と、絶縁部とを有する。正極集電体は、セパレータの第１の辺を越えて延出する正極リードを有している。正極活物質は、セパレータの外周縁よりも内側の範囲の正極集電体の両面を覆う。絶縁部は、正極活物質の縁から離れた位置の正極リードの両面に形成される。また、負極は、負極集電体と、負極活物質とを有する。負極集電体は、セパレータの第２の辺を越えて延出する負極リードを有している。負極活物質は、セパレータの外周縁よりも内側で正極活物質が形成された範囲よりも広い範囲の負極集電体の両面を覆う。絶縁部は、第１の絶縁層と、第２の絶縁層とを含む。第１の絶縁層は、電解液を透過させない中実に正極リードを覆う。第２の絶縁層は、電解液が透過する空隙を有し第１の絶縁層を覆う。   A secondary battery according to an embodiment of the present invention includes a core having a structure in which positive electrodes and negative electrodes are alternately stacked with a separator having a first side and a second side of the opposite side interposed therebetween. The positive electrode includes a positive electrode current collector, a positive electrode active material, and an insulating part. The positive electrode current collector has a positive electrode lead that extends beyond the first side of the separator. The positive electrode active material covers both surfaces of the positive electrode current collector in a range inside the outer peripheral edge of the separator. The insulating part is formed on both surfaces of the positive electrode lead at a position away from the edge of the positive electrode active material. The negative electrode has a negative electrode current collector and a negative electrode active material. The negative electrode current collector has a negative electrode lead that extends beyond the second side of the separator. The negative electrode active material covers both surfaces of the negative electrode current collector in a wider range than the range where the positive electrode active material is formed inside the outer peripheral edge of the separator. The insulating part includes a first insulating layer and a second insulating layer. The first insulating layer covers the positive electrode lead in a solid state that does not allow the electrolytic solution to pass therethrough. The second insulating layer has a gap through which the electrolytic solution passes and covers the first insulating layer.

このとき、絶縁部は、負極活物質が形成された範囲の内側から少なくとも負極活物質の縁を越える位置までの範囲に形成される。または、絶縁部は、負極活物質が形成された範囲の内側から少なくともセパレータの外周縁までの範囲に形成される。また、第１の絶縁層は、第２の絶縁層よりも薄い。   At this time, the insulating portion is formed in a range from the inside of the range where the negative electrode active material is formed to at least a position beyond the edge of the negative electrode active material. Alternatively, the insulating portion is formed in a range from the inside of the range where the negative electrode active material is formed to at least the outer peripheral edge of the separator. The first insulating layer is thinner than the second insulating layer.

本発明に係る二次電池によれば、正極リードの基部に絶縁部が形成されているので、製造時に混入する導電性の異物が接触しても正極が負極に短絡されない。また、絶縁部は、電解液を透過させない中実に正極リードを覆う第１の絶縁層と、電解液が透過する空隙を有した第２の絶縁層とを含む。したがって、正極活物質が形成された内側へ電解液が透過することを妨げることなく、また、内側で発生したガスを第２の絶縁層を通して排出することができる。そして、電解液中のイオンが正極リードの周辺に析出してデンドライトを形成しても、正極が負極に短絡することを第１の絶縁層によって確実に防ぐことができる。また、絶縁部は、正極活物質の縁から離れた位置に形成されるので、正極活物質の縁からイオンが放出されることを妨げない。つまり、正極活物質が形成された範囲を最大に活用できるため、絶縁部を有した本発明の二次電池は、絶縁部を有していない二次電池に比べて、発電効率及び充電効率を低下させない、すなわち維持することができる。   According to the secondary battery of the present invention, since the insulating portion is formed at the base portion of the positive electrode lead, the positive electrode is not short-circuited to the negative electrode even when conductive foreign matter mixed in at the time of manufacture comes into contact. The insulating portion includes a first insulating layer that covers the positive electrode lead that does not allow the electrolytic solution to pass therethrough, and a second insulating layer that has a gap through which the electrolytic solution passes. Therefore, the gas generated inside can be discharged through the second insulating layer without preventing the electrolyte from permeating into the inside where the positive electrode active material is formed. Even if ions in the electrolytic solution are deposited around the positive electrode lead to form dendrites, the first insulating layer can reliably prevent the positive electrode from being short-circuited to the negative electrode. Moreover, since the insulating part is formed at a position away from the edge of the positive electrode active material, it does not prevent ions from being released from the edge of the positive electrode active material. In other words, since the range in which the positive electrode active material is formed can be utilized to the maximum, the secondary battery of the present invention having an insulating part has higher power generation efficiency and charging efficiency than a secondary battery having no insulating part. It cannot be reduced, i.e. maintained.

負極活物質が形成された範囲の内側から少なくとも負極活物質の縁を越える位置までの範囲に絶縁部が形成される発明の二次電池によれば、絶縁部と負極との間にセパレータの縁をしっかりと保持することができる。また、負極活物質が形成された範囲の内側から少なくともセパレータの外周縁までの範囲に絶縁部が形成される発明の二次電池によれば、積層方向に比べて正極に沿う方向に十分な長さを有している。したがって、デンドライトが析出しても、正極活物質が形成された領域へデンドライトが到達することを確実に抑制する。さらに、第１の絶縁層が第２の絶縁層よりも薄い発明の二次電池によれば、発生したガス及び電解液の透過経路が広くなるので、電解液が浸入しやすく、かつ、ガスが排出されやすくなる。   According to the secondary battery of the invention in which the insulating part is formed in a range from the inside of the range where the negative electrode active material is formed to at least a position beyond the edge of the negative electrode active material, the edge of the separator is formed between the insulating part and the negative electrode. Can be held firmly. In addition, according to the secondary battery of the invention in which the insulating portion is formed in the range from the inside of the range where the negative electrode active material is formed to at least the outer peripheral edge of the separator, the secondary battery is sufficiently long in the direction along the positive electrode compared to the stacking direction. Have Therefore, even if dendrite is deposited, it is reliably prevented from reaching the region where the positive electrode active material is formed. Furthermore, according to the secondary battery of the invention in which the first insulating layer is thinner than the second insulating layer, the permeation path of the generated gas and electrolyte is widened, so that the electrolyte can easily enter and the gas It becomes easy to be discharged.

本発明に係る第１の実施形態の二次電池の斜視図。1 is a perspective view of a secondary battery according to a first embodiment of the present invention. 図１に示した二次電池のコアの分解斜視図。The disassembled perspective view of the core of the secondary battery shown in FIG. 図２に示したコアの積層部分を拡大した断面図。Sectional drawing which expanded the lamination | stacking part of the core shown in FIG. 図３に示した正極の絶縁部の周辺を拡大した断面図。Sectional drawing which expanded the periphery of the insulation part of the positive electrode shown in FIG.

本発明に係る第１の実施形態の二次電池について、リチウムイオン電池１に適用した場合を一例に、図１から図４を参照して説明する。図１に示すリチウムイオン電池１は、コア１０及び電解液をケース２の中に収納しており、開口部２１に蓋３が取り付けられている。ケース２は、図１に示すような角型の容器である以外に、円筒型であってもよいし、ラミネートフィルムで形成された袋状のものでもよい。正極端子１０１および負極端子１０２は、それぞれ蓋３を貫通して取り付けられている。   The secondary battery according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4, taking as an example a case where the secondary battery is applied to a lithium ion battery 1. A lithium ion battery 1 shown in FIG. 1 houses a core 10 and an electrolyte in a case 2, and a lid 3 is attached to an opening 21. The case 2 may be a cylindrical shape or a bag shape formed of a laminate film other than the rectangular container as shown in FIG. The positive terminal 101 and the negative terminal 102 are attached through the lid 3, respectively.

コア１０は、セパレータ１３を間に挟んで正極１１および負極１２が交互に積層配置された構造を有している。本実施形態のコア１０は、図２に示すように、帯状に長いセパレータ１３を間に挟んで、同じくそれぞれ帯状に長い正極１１と負極１２とを巻いた捲回型のコア１０である。   The core 10 has a structure in which positive electrodes 11 and negative electrodes 12 are alternately stacked with a separator 13 interposed therebetween. As shown in FIG. 2, the core 10 according to the present embodiment is a wound core 10 in which a strip-like long separator 13 is sandwiched and a long positive electrode 11 and a negative electrode 12 are wound around each other.

本実施形態において、セパレータ１３は、図２に示すように帯状の長手方向に、第１の辺１３１とこの対辺に位置する第２の辺１３２とを有する。セパレータ１３は、例えば、ポリエチレンやポリプロピレンなどのポリオレフィン系微多孔膜で作られており、その空孔中に電解液を流動させるとともに保持する。   In this embodiment, the separator 13 has the 1st edge | side 131 and the 2nd edge | side 132 located in this other side in a strip | belt-shaped longitudinal direction, as shown in FIG. The separator 13 is made of, for example, a polyolefin microporous film such as polyethylene or polypropylene, and flows and holds the electrolyte in the pores.

正極１１は、図３に示すように正極集電体１１１と正極活物質１１２と絶縁部１４とを有する。正極集電体１１１は、セパレータ１３の有する第１の辺１３１から延出する正極リード１１３を具備している。この実施形態において正極集電体１１１は、アルミニウム箔である。正極活物質１１２は、セパレータ１３の外周縁１３Ａよりも内側の範囲の正極集電体１１１の両面を覆うように形成される。正極活物質１１２は、電極材料の粉末を溶媒で溶いてスラリーにし、正極集電体１１１の両側の面に均質に塗工され、乾燥されることによって、形成される。正極活物質１１２の一例としてマンガン酸リチウムが採用される。   As shown in FIG. 3, the positive electrode 11 includes a positive electrode current collector 111, a positive electrode active material 112, and an insulating portion 14. The positive electrode current collector 111 includes a positive electrode lead 113 extending from the first side 131 of the separator 13. In this embodiment, the positive electrode current collector 111 is an aluminum foil. The positive electrode active material 112 is formed so as to cover both surfaces of the positive electrode current collector 111 in the range inside the outer peripheral edge 13 </ b> A of the separator 13. The positive electrode active material 112 is formed by dissolving powder of an electrode material with a solvent to form a slurry, which is uniformly coated on both sides of the positive electrode current collector 111 and dried. As an example of the positive electrode active material 112, lithium manganate is employed.

絶縁部１４は、図３及び図４に示すように、正極活物質１１２の縁１１２Ａから離れた位置の正極リード１１３の両面に形成される。本実施形態では、絶縁部１４は、図２に示すように、正極活物質１１２の縁１１２Ａに平行に形成される。絶縁部１４は、正極活物質１１２と同様に、スラリーにして塗工される。絶縁部１４は、正極活物質１１２から離れて形成されるので、正極活物質１１２と同時に塗工されてもよいし、正極活物質１１２の前にまたは後に塗工されてもよい。   As shown in FIGS. 3 and 4, the insulating portion 14 is formed on both surfaces of the positive electrode lead 113 at a position away from the edge 112 </ b> A of the positive electrode active material 112. In the present embodiment, the insulating portion 14 is formed in parallel to the edge 112A of the positive electrode active material 112, as shown in FIG. The insulating part 14 is applied in the form of a slurry in the same manner as the positive electrode active material 112. Since the insulating part 14 is formed away from the positive electrode active material 112, it may be applied simultaneously with the positive electrode active material 112, or may be applied before or after the positive electrode active material 112.

負極１２は、負極集電体１２１と負極活物質１２２とを有する。負極集電体１２１は、セパレータ１３の有する第２の辺１３２から延出する負極リード１２３を具備している。この実施形態において負極集電体１２１は、銅箔である。負極活物質１２２は、セパレータ１３の外周縁１３Ａよりも内側の範囲で、かつ、正極活物質１１２が形成された範囲よりも広い範囲の負極集電体１２１の両面を覆うように形成される。負極活物質１２２は、正極活物質１１２と同様に、スラリーにして塗工される。負極活物質１２２の一例として黒鉛が採用される。   The negative electrode 12 includes a negative electrode current collector 121 and a negative electrode active material 122. The negative electrode current collector 121 includes a negative electrode lead 123 extending from the second side 132 of the separator 13. In this embodiment, the negative electrode current collector 121 is a copper foil. The negative electrode active material 122 is formed so as to cover both surfaces of the negative electrode current collector 121 in a range inside the outer peripheral edge 13A of the separator 13 and in a range wider than the range where the positive electrode active material 112 is formed. The negative electrode active material 122 is applied as a slurry in the same manner as the positive electrode active material 112. As an example of the negative electrode active material 122, graphite is employed.

さらに本実施形態の場合、絶縁部１４は、図３及び図４に示すように、第１の絶縁層１４１と第２の絶縁層１４２を含む二層構造を有している。第１の絶縁層１４１は、電解液を透過させない中実な部材であり、正極リード１１３を覆う。第１の絶縁層１４１は、電解液と反応しない合成樹脂製の材料、例えばポリオレフィンやアラミド、カルボキシメチルセルロース（ＣＭＣ）など、好ましくはセパレータ１３と同じ素材やセパレータよりも耐熱性の高い素材で形成される。この第１の絶縁層１４１の厚みＴ４１は、正極活物質１１２の厚みＴ１よりも薄い。   Further, in the present embodiment, the insulating portion 14 has a two-layer structure including a first insulating layer 141 and a second insulating layer 142, as shown in FIGS. The first insulating layer 141 is a solid member that does not allow the electrolytic solution to pass therethrough and covers the positive electrode lead 113. The first insulating layer 141 is formed of a synthetic resin material that does not react with the electrolyte, such as polyolefin, aramid, carboxymethylcellulose (CMC), or the like, preferably the same material as the separator 13 or a material having higher heat resistance than the separator. The The thickness T41 of the first insulating layer 141 is thinner than the thickness T1 of the positive electrode active material 112.

第２の絶縁層１４２は、電解液が透過する空隙を有した部材であり、第１の絶縁層１４１を覆って形成される。第２の絶縁層１４２の材料として塗膜を形成するものであれば、ポリエチレンやポリプロピレンなどのポリオレフィン系の有機材料や、セラミック系の無機材料を採用することができる。   The second insulating layer 142 is a member having a gap through which the electrolytic solution passes, and is formed so as to cover the first insulating layer 141. Any material that forms a coating film as the material of the second insulating layer 142 may be a polyolefin-based organic material such as polyethylene or polypropylene, or a ceramic-based inorganic material.

セラミック系の無機材料の一例をあげると、正極１１の正極集電体１１１の材料であるアルミ箔との化学反応が起こらないイオン化傾向の大きな金属の酸化物で、かつ電解液との化学反応も起こらない素材、具体的には、アルミナや、シリカなどであることが好ましい。第２の絶縁層１４２としてセラミック系の無機材料を採用することによって、リチウムイオン電池１が熱暴走して正極集電体に密着された第１の絶縁層１４１として採用したポリオレフィンの樹脂材料が融解した場合でも、第２の絶縁層１４２が正極１１と負極１２との間の絶縁機能を維持することができる。   An example of a ceramic-based inorganic material is an oxide of a metal having a large ionization tendency that does not cause a chemical reaction with the aluminum foil that is the material of the positive electrode current collector 111 of the positive electrode 11, and also has a chemical reaction with the electrolytic solution. A material that does not occur, specifically, alumina or silica is preferable. By adopting a ceramic inorganic material as the second insulating layer 142, the polyolefin resin material employed as the first insulating layer 141 in which the lithium ion battery 1 is thermally runaway and is in close contact with the positive electrode current collector is melted. Even in this case, the second insulating layer 142 can maintain the insulating function between the positive electrode 11 and the negative electrode 12.

また、絶縁部１４は、負極活物質１２２が形成された範囲の内側から少なくとも負極活物質１２２の縁１２２Ａを越える位置までの範囲に形成される。本実施形態では、図３及び図４に示すように、負極活物質１２２が形成された範囲の内側から少なくともセパレータ１３の外周縁１３Ａを越える位置までの範囲に、絶縁部１４が形成されている。つまり、コア１０の内部に面した絶縁部１４の端部１４Ａは、負極活物質１２２が形成された範囲の内側に位置しており、コア１０の外部に面した絶縁部１４の端部１４Ｂは、セパレータ１３の外周縁１３Ａよりも外側に位置する。正極１１と負極１２の積層方向に絶縁部１４の厚みＴ４は、内側の端部１４Ａから外側の端部１４Ｂまで均一であり、正極活物質１１２の厚みＴ１と同じである。そして、第１の絶縁層１４１の厚みＴ４１は、第２の絶縁層１４２の厚みＴ４２よりも薄い。   The insulating portion 14 is formed in a range from the inside of the range where the negative electrode active material 122 is formed to at least a position beyond the edge 122A of the negative electrode active material 122. In this embodiment, as shown in FIGS. 3 and 4, the insulating portion 14 is formed in a range from the inside of the range where the negative electrode active material 122 is formed to a position exceeding at least the outer peripheral edge 13 </ b> A of the separator 13. . That is, the end portion 14A of the insulating portion 14 facing the inside of the core 10 is located inside the range where the negative electrode active material 122 is formed, and the end portion 14B of the insulating portion 14 facing the outside of the core 10 is The separator 13 is located outside the outer peripheral edge 13A. The thickness T4 of the insulating portion 14 in the stacking direction of the positive electrode 11 and the negative electrode 12 is uniform from the inner end portion 14A to the outer end portion 14B, and is the same as the thickness T1 of the positive electrode active material 112. The thickness T41 of the first insulating layer 141 is thinner than the thickness T42 of the second insulating layer 142.

このように絶縁部１４を形成することによって、セパレータ１３の外周縁１３Ａは、絶縁部１４と負極１２の端部１２Ａの間に保持される。特に、図４に示すようにセパレータの外周縁１３Ａを越える位置まで絶縁部１４が形成される本実施形態のリチウムイオン電池１の場合、積層方向に対して正極集電体１１１に沿う方向へ十分な長さを有しているので、第２の絶縁層１４２の空隙にデンドライトが成長しても、デンドライトが絶縁部１４を越えて正極活物質１１２に到達することはない。   By forming the insulating portion 14 in this way, the outer peripheral edge 13A of the separator 13 is held between the insulating portion 14 and the end portion 12A of the negative electrode 12. In particular, as shown in FIG. 4, in the case of the lithium ion battery 1 of the present embodiment in which the insulating portion 14 is formed up to the position beyond the outer peripheral edge 13A of the separator, it is sufficient in the direction along the positive electrode current collector 111 with respect to the stacking direction. Therefore, even if dendrite grows in the gap of the second insulating layer 142, the dendrite does not reach the positive electrode active material 112 beyond the insulating portion 14.

以上のように構成されたリチウムイオン電池１によれば、製造過程において導電性の異物が混入していても、絶縁部１４を有しているので、異物によって正極１１が負極１２に短絡されることを防止される。この絶縁部１４は、中実な第１の絶縁層１４１と空隙を有した第２の絶縁層１４２で構成されている。電解液や正極集電体１１１の近傍で発生するガスは、第２の絶縁層１４２を透過することができる。したがって、製造過程において電解液がコア１０の内部へ浸透しやすく、また、製造直後の充放電によって生じるガスもコア１０から排出されやすい。   According to the lithium ion battery 1 configured as described above, the positive electrode 11 is short-circuited to the negative electrode 12 by the foreign matter because the insulating portion 14 is provided even if conductive foreign matter is mixed in the manufacturing process. To be prevented. The insulating portion 14 includes a solid first insulating layer 141 and a second insulating layer 142 having a gap. Gas generated in the vicinity of the electrolytic solution and the positive electrode current collector 111 can pass through the second insulating layer 142. Therefore, the electrolytic solution easily penetrates into the core 10 during the manufacturing process, and gas generated by charging / discharging immediately after the manufacturing is easily discharged from the core 10.

また、異物が電解液に溶解するあるいは電解液中の溶存金属が正極リード１１３の近傍で析出することによって絶縁部１４の第２の絶縁層１４２にデンドライトが成長しても、絶縁部１４の第１の絶縁層１４１によって、デンドライトが正極リード１１３に達することを防ぐことができる。   In addition, even if dendrites grow on the second insulating layer 142 of the insulating portion 14 due to the foreign matter being dissolved in the electrolytic solution or the dissolved metal in the electrolytic solution being deposited in the vicinity of the positive electrode lead 113, the first of the insulating portion 14 One insulating layer 141 can prevent dendrite from reaching the positive electrode lead 113.

さらに、第１の絶縁層１４１の厚みが正極活物質１１２の厚みよりも薄いので、電池を組み立てた直後に充電及び放電を行うことで正極リード１１３側の正極１１の周りに発生するガスは、第２の絶縁層１４２を通してコア１０の外へ排出されやすくなる。   Further, since the thickness of the first insulating layer 141 is thinner than the thickness of the positive electrode active material 112, the gas generated around the positive electrode 11 on the positive electrode lead 113 side by charging and discharging immediately after the battery is assembled is It becomes easy to be discharged out of the core 10 through the second insulating layer 142.

なお、本発明に係る二次電池は、リチウムイオン電池１を一例に、捲回型のコアを採用する場合を例に説明した。本発明に係る二次電池の技術は、セパレータを挿んで正極と負極とが積層され、正極リードがセパレータの第１の辺から延出し、負極リードがセパレータの第２の辺から延出している積層型のコアを有する二次電池に採用することもできる。本発明に係る二次電池の技術を積層型のコアを有する二次電池に採用した場合にも、捲回型のコアを有する二次電池と同様の効果を得ることができる。   The secondary battery according to the present invention has been described by taking the lithium ion battery 1 as an example and the case where a wound core is employed as an example. In the secondary battery technology according to the present invention, a positive electrode and a negative electrode are stacked by inserting a separator, a positive electrode lead extends from the first side of the separator, and a negative electrode lead extends from the second side of the separator. It can also be employed in a secondary battery having a laminated core. Even when the technology of the secondary battery according to the present invention is applied to a secondary battery having a laminated core, the same effect as that of a secondary battery having a wound core can be obtained.

１…リチウムイオン電池（二次電池）、１０…コア、１１…正極、１１１…正極集電体、１１２…正極活物質、１１２Ａ…縁、１１３…正極リード、１２…負極、１２１…負極集電体、１２２…負極活物質、１２３…負極リード、１３…セパレータ、１３Ａ…外周縁、１３１…第１の辺、１３２…第２の辺、１４…絶縁部、１４１…第１の絶縁層、１４２…第２の絶縁層。   DESCRIPTION OF SYMBOLS 1 ... Lithium ion battery (secondary battery), 10 ... Core, 11 ... Positive electrode, 111 ... Positive electrode collector, 112 ... Positive electrode active material, 112A ... Edge, 113 ... Positive electrode lead, 12 ... Negative electrode, 121 ... Negative electrode current collector Body, 122 ... negative electrode active material, 123 ... negative electrode lead, 13 ... separator, 13A ... outer periphery, 131 ... first side, 132 ... second side, 14 ... insulating part, 141 ... first insulating layer, 142 ... second insulating layer.

Claims (4)

外周縁に第１の辺とこの対辺の第２の辺とを有するセパレータを間に挟んで正極及び負極を交互に積層した構造のコアを備える二次電池であって、
前記正極は、前記セパレータの有する前記第１の辺を越えて延出する正極リードを具備した正極集電体と、前記セパレータの外周縁よりも内側の範囲の前記正極集電体の両面を覆う正極活物質と、前記正極活物質の縁から離れた位置の前記正極リードの両面に形成される絶縁部と、を有し、
前記負極は、前記セパレータの有する前記第２の辺を越えて延出する負極リードを具備した負極集電体と、前記セパレータの外周縁よりも内側で前記正極活物質が形成された範囲よりも広い範囲の前記負極集電体の両面を覆う負極活物質と、を有し、
前記絶縁部は、電解液を透過させない中実に前記正極リードを覆う第１の絶縁層と、電解液が透過する空隙を有し前記第１の絶縁層を覆う第２の絶縁層と、を含む
ことを特徴とする二次電池。 A secondary battery including a core having a structure in which a positive electrode and a negative electrode are alternately stacked with a separator having a first side and a second side of the opposite side interposed therebetween,
The positive electrode covers both surfaces of the positive electrode current collector having a positive electrode lead extending beyond the first side of the separator and the positive electrode current collector in a range inside the outer peripheral edge of the separator. A positive electrode active material, and an insulating part formed on both surfaces of the positive electrode lead at a position away from the edge of the positive electrode active material,
The negative electrode includes a negative electrode current collector having a negative electrode lead extending beyond the second side of the separator, and a range in which the positive electrode active material is formed inside an outer peripheral edge of the separator. A negative electrode active material covering both surfaces of the negative electrode current collector in a wide range,
The insulating portion includes a first insulating layer that covers the positive electrode lead that does not allow electrolyte to permeate, and a second insulating layer that has a gap through which the electrolyte passes and covers the first insulating layer. A secondary battery characterized by that. 前記絶縁部は、前記負極活物質が形成された範囲の内側から少なくとも前記負極活物質の縁を越える位置までの範囲に形成される
ことを特徴とする請求項１に記載された二次電池。 2. The secondary battery according to claim 1, wherein the insulating part is formed in a range from the inside of the range where the negative electrode active material is formed to a position at least beyond the edge of the negative electrode active material. 前記絶縁部は、前記負極活物質が形成された範囲の内側から少なくとも前記セパレータの外周縁までの範囲に形成される
ことを特徴とする請求項１に記載された二次電池。 The secondary battery according to claim 1, wherein the insulating part is formed in a range from an inside of a range where the negative electrode active material is formed to at least an outer peripheral edge of the separator. 前記第１の絶縁層は、前記第２の絶縁層よりも積層方向に薄い
ことを特徴とする請求項１に記載された二次電池。 The secondary battery according to claim 1, wherein the first insulating layer is thinner than the second insulating layer in a stacking direction.
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