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JP6911463B2 - Power storage device - Google Patents
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JP6911463B2 - Power storage device - Google Patents

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JP6911463B2
JP6911463B2 JP2017068905A JP2017068905A JP6911463B2 JP 6911463 B2 JP6911463 B2 JP 6911463B2 JP 2017068905 A JP2017068905 A JP 2017068905A JP 2017068905 A JP2017068905 A JP 2017068905A JP 6911463 B2 JP6911463 B2 JP 6911463B2
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electrode
edge portion
active material
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negative electrode
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JP2018170243A (en
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厚志 南形
厚志 南形
雅人 小笠原
雅人 小笠原
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Toyota Industries 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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  • Connection Of Batteries Or Terminals (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Electric Double-Layer Capacitors Or The Like (AREA)
  • Cell Separators (AREA)

Description

本発明は、電極組立体及び電極組立体を覆う絶縁シートを備える蓄電装置に関する。 The present invention relates to an electrode assembly and a power storage device including an insulating sheet covering the electrode assembly.

ＥＶ（Electric Vehicle）やＰＨＶ（Plug-in Hybrid Vehicle）などの車両には、走行用モータへの供給電力を蓄える蓄電装置としての二次電池が搭載されている。二次電池は、シート状の正極電極及び負極電極が積層された電極組立体と、当該電極組立体を収容する有底筒状のケースとを備えている。また、電極組立体を袋状に形成された絶縁シートによって覆うことで、電極組立体とケースとを絶縁させている（特許文献１参照）。 Vehicles such as EVs (Electric Vehicles) and PHVs (Plug-in Hybrid Vehicles) are equipped with a secondary battery as a power storage device that stores the power supplied to the traveling motor. The secondary battery includes an electrode assembly in which a sheet-shaped positive electrode and a negative electrode are laminated, and a bottomed tubular case for accommodating the electrode assembly. Further, the electrode assembly is insulated from the case by covering the electrode assembly with an insulating sheet formed in a bag shape (see Patent Document 1).

特開２０１４−３８７３６号公報Japanese Unexamined Patent Publication No. 2014-38736

ところで、二次電池の充放電時、正極電極及び負極電極は、面に沿う方向（面方向）の外側へ膨張したり内側へ収縮したりする。このため、絶縁シートは、面方向の外側へ膨張した電極の縁部によってケース側へ押圧される。そして、電極の膨張量が大きくなると、絶縁シートは電極の縁部によって突き破られるおそれがある。絶縁シートが破れると、電極組立体とケースが短絡してしまう。 By the way, when the secondary battery is charged and discharged, the positive electrode and the negative electrode expand outward or contract inward in the direction along the surface (plane direction). Therefore, the insulating sheet is pressed toward the case by the edge of the electrode that expands outward in the surface direction. Then, when the expansion amount of the electrode becomes large, the insulating sheet may be pierced by the edge portion of the electrode. If the insulating sheet is torn, the electrode assembly and the case will be short-circuited.

本発明は、上記課題を解決するためになされたものであり、その目的は、電極の膨張による絶縁シートの破れを抑制できる蓄電装置を提供することにある。 The present invention has been made to solve the above problems, and an object of the present invention is to provide a power storage device capable of suppressing tearing of an insulating sheet due to expansion of electrodes.

上記問題点を解決するための蓄電装置は、第１の電極と、前記第１の電極と異なる極性であるとともに前記第１の電極の外形よりも大きい外形の第２の電極とを互いに絶縁した状態で積層した電極組立体と、前記電極組立体を覆う絶縁シートと、を備え、前記第１の電極及び前記第２の電極は、矩形シート状の集電体と、該集電体の片面又は両面に存在する活物質層と、前記集電体の一辺に沿う第１縁部から突出する形状のタブと、を有するとともに、前記第１縁部の対辺である第２縁部と、前記第１縁部と前記第２縁部の一端を繋ぐ第３縁部と、前記第３縁部の対辺である第４縁部とを備え、前記第２の電極の面に沿う方向を面方向としたとき、積層方向から前記電極組立体を見て、前記第１の電極は、前記第２の電極の第１〜第４縁部よりも前記面方向の内側に位置している蓄電装置であって、前記第２の電極は、前記第２〜第４縁部に沿って前記活物質層が存在せず前記集電体が露出した未塗工部を有し、前記活物質層と前記未塗工部との境界部は、前記第２〜第４縁部と平行に存在することを要旨とする。 The power storage device for solving the above problems insulates the first electrode and the second electrode having a polarity different from that of the first electrode and having an outer shape larger than the outer shape of the first electrode. The electrode assembly laminated in the state and an insulating sheet covering the electrode assembly are provided, and the first electrode and the second electrode are a rectangular sheet-shaped current collector and one side of the current collector. Alternatively, it has an active material layer existing on both sides and a tab having a shape protruding from the first edge portion along one side of the current collector, and also has a second edge portion which is the opposite side of the first edge portion and the said. A third edge portion connecting the first edge portion and one end of the second edge portion and a fourth edge portion opposite to the third edge portion are provided, and the direction along the surface of the second electrode is the plane direction. When the electrode assembly is viewed from the stacking direction, the first electrode is a power storage device located inside the first to fourth edges of the second electrode in the plane direction. The second electrode has an uncoated portion in which the active material layer does not exist and the current collector is exposed along the second to fourth edges, and the active material layer and the said. The gist is that the boundary portion with the unpainted portion exists in parallel with the second to fourth edge portions.

蓄電装置を充放電させると、第１の電極及び第２の電極は、面方向外側に膨張したり面方向内側に収縮したりする。面方向外側へ膨張する第２の電極の縁部は、絶縁シートをケース側に押圧する。しかしながら、第２〜第４縁部に沿って金属箔が露出した未塗工部が存在するため、活物質層が存在する他の部分と比べて剛性が低い。よって、第２の電極において第２〜第４縁部に沿う部分は折れ曲がり、絶縁シートを突き破ることが抑制される。また、境界部が第２〜第４縁部と平行に存在することで、第２〜第４縁部に沿う部分の膨張量は縁部全体でほぼ同じになる。つまり、絶縁シートは、縁部全体によって押圧されるため、縁部の一部によって押圧される場合と比べて、絶縁シートにかかる荷重を分散できる。その結果、電極の膨張による絶縁シートの破れを抑制できる。 When the power storage device is charged and discharged, the first electrode and the second electrode expand outward in the plane direction or contract inward in the plane direction. The edge of the second electrode, which expands outward in the plane direction, presses the insulating sheet toward the case. However, since there is an uncoated portion where the metal foil is exposed along the second to fourth edges, the rigidity is lower than that of the other portion where the active material layer is present. Therefore, the portion of the second electrode along the second to fourth edges is bent and is prevented from breaking through the insulating sheet. Further, since the boundary portion exists in parallel with the second to fourth edge portions, the amount of expansion of the portion along the second to fourth edge portions is substantially the same for the entire edge portion. That is, since the insulating sheet is pressed by the entire edge portion, the load applied to the insulating sheet can be dispersed as compared with the case where the insulating sheet is pressed by a part of the edge portion. As a result, the tearing of the insulating sheet due to the expansion of the electrodes can be suppressed.

また、上記蓄電装置について、前記面方向は、前記第１縁部及び前記第２縁部と直交する第１方向と、前記第３縁部及び前記第４縁部と直交する第２方向とを有し、前記第２縁部に沿って存在する未塗工部の第１方向に沿う寸法、及び前記第３縁部及び前記第４縁部に沿って存在する未塗工部の第２方向に沿う寸法は、それぞれ、前記第２の電極の前記集電体及び前記活物質層の厚さ方向の寸法よりも大きいのが好ましい。 Further, with respect to the power storage device, the plane direction is a first direction orthogonal to the first edge portion and the second edge portion, and a second direction orthogonal to the third edge portion and the fourth edge portion. The dimensions of the uncoated portion along the second edge portion along the first direction, and the second direction of the uncoated portion existing along the third edge portion and the fourth edge portion. It is preferable that the dimensions along the above-mentioned are larger than the dimensions in the thickness direction of the current collector and the active material layer of the second electrode, respectively.

これによれば、折れ曲がった未塗工部は、境界部、すなわち第２の電極の活物質層の縁部を厚さ方向に覆った状態となる。このため、折れ曲がった未塗工部により、第２の電極の活物質層を絶縁シートに接触させないようにでき、電極の膨張による絶縁シートの破れをより抑制できる。 According to this, the bent uncoated portion covers the boundary portion, that is, the edge portion of the active material layer of the second electrode in the thickness direction. Therefore, the bent uncoated portion can prevent the active material layer of the second electrode from coming into contact with the insulating sheet, and the tearing of the insulating sheet due to the expansion of the electrode can be further suppressed.

また、上記蓄電装置について、前記第２の電極は、負極電極であるのが好ましい。
一般に負極電極の外形の方が正極電極の外形よりも大きく設定されるため、負極電極の第２〜第４縁部の方が正極電極の第２〜第４縁部よりも絶縁シートに接触しやすい。このため、負極電極の第２〜第４縁部に沿って未塗工部を設けることで、負極電極の膨張による絶縁シートの破れを抑制できる。 Further, regarding the power storage device, the second electrode is preferably a negative electrode.
Generally, the outer shape of the negative electrode is set larger than the outer shape of the positive electrode, so that the second to fourth edges of the negative electrode come into contact with the insulating sheet more than the second to fourth edges of the positive electrode. Cheap. Therefore, by providing the uncoated portion along the second to fourth edges of the negative electrode, it is possible to suppress the tearing of the insulating sheet due to the expansion of the negative electrode.

また、上記蓄電装置について、前記負極電極の活物質層は、ケイ素を含むのが好ましい。
ケイ素を含む活物質層の膨張率は、ケイ素を含まない活物質層の膨張率よりも大きいため、電極の膨張による絶縁シートの破れが発生しやすい。このため、活物質層にケイ素を含む電極の第２〜第４縁部に沿って未塗工部を設けることで、電極の膨張による絶縁シートの破れを抑制できる。 Further, with respect to the power storage device, the active material layer of the negative electrode preferably contains silicon.
Since the expansion coefficient of the active material layer containing silicon is larger than the expansion coefficient of the active material layer containing no silicon, the insulating sheet is likely to be torn due to the expansion of the electrodes. Therefore, by providing the uncoated portion along the second to fourth edges of the electrode containing silicon in the active material layer, it is possible to suppress the tearing of the insulating sheet due to the expansion of the electrode.

本発明によれば、電極の膨張による絶縁シートの破れを抑制できる。 According to the present invention, it is possible to suppress the tearing of the insulating sheet due to the expansion of the electrodes.

実施形態の二次電池の分解斜視図。An exploded perspective view of the secondary battery of the embodiment. 電極組立体の分解斜視図。An exploded perspective view of the electrode assembly. 電極組立体の平面図。Top view of the electrode assembly. （ａ），（ｂ）は実施形態の二次電池の作用を説明するための拡大断面図。(A) and (b) are enlarged cross-sectional views for explaining the operation of the secondary battery of the embodiment.

以下、蓄電装置を二次電池に具体化した一実施形態を図１〜図４にしたがって説明する。
図１に示すように、蓄電装置としての二次電池１０は、ケース１１を備える。二次電池１０は、ケース１１に収容された電極組立体１２を備える。ケース１１は、直方体状のケース本体１３と、ケース本体１３の開口部１３ａを閉塞する矩形平板状の蓋１４とを有する。ケース１１を構成するケース本体１３と蓋１４は、何れも金属製（例えば、ステンレスやアルミニウム）である。また、本実施形態の二次電池１０は、その外観が角型をなす角型電池である。また、本実施形態の二次電池１０は、リチウムイオン電池である。 Hereinafter, an embodiment in which the power storage device is embodied in a secondary battery will be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the secondary battery 10 as a power storage device includes a case 11. The secondary battery 10 includes an electrode assembly 12 housed in a case 11. The case 11 has a rectangular parallelepiped case body 13 and a rectangular flat plate-shaped lid 14 that closes the opening 13a of the case body 13. The case body 13 and the lid 14 constituting the case 11 are both made of metal (for example, stainless steel or aluminum). Further, the secondary battery 10 of the present embodiment is a square battery having a square appearance. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

ケース本体１３は、底壁１３ｂと、底壁１３ｂに繋がる第１〜第４壁部１３ｃ〜１３ｆとを備える。ケース本体１３は、底壁１３ｂの一対の長縁部に繋がる壁部のうちの一方の壁部に第１壁部１３ｃを備え、第１壁部１３ｃと対面する他方の壁部に第２壁部１３ｄを備える。また、ケース本体１３は、第１壁部１３ｃと第２壁部１３ｄとを繋ぎ、底壁１３ｂの一対の短縁部に繋がる壁部のうちの一方の壁部に第３壁部１３ｅを備え、第３壁部１３ｅと対面する他方の壁部に第４壁部１３ｆを備える。 The case body 13 includes a bottom wall 13b and first to fourth wall portions 13c to 13f connected to the bottom wall 13b. The case body 13 is provided with a first wall portion 13c on one of the wall portions connected to the pair of long edges of the bottom wall 13b, and a second wall on the other wall portion facing the first wall portion 13c. A unit 13d is provided. Further, the case body 13 is provided with a third wall portion 13e on one of the wall portions that connects the first wall portion 13c and the second wall portion 13d and is connected to the pair of short edge portions of the bottom wall 13b. A fourth wall portion 13f is provided on the other wall portion facing the third wall portion 13e.

二次電池１０は、電極組立体１２から電気を取り出すための正極端子１５と負極端子１６を備える。正極端子１５と負極端子１６は、蓋１４に所定の間隔をあけて並設された一対の孔１４ａからケース１１の外部に露出される。また、正極端子１５及び負極端子１６には、ケース１１から絶縁するためのリング状の絶縁リング１７ａがそれぞれ取り付けられている。 The secondary battery 10 includes a positive electrode terminal 15 and a negative electrode terminal 16 for extracting electricity from the electrode assembly 12. The positive electrode terminal 15 and the negative electrode terminal 16 are exposed to the outside of the case 11 through a pair of holes 14a arranged side by side on the lid 14 at predetermined intervals. Further, a ring-shaped insulating ring 17a for insulating from the case 11 is attached to the positive electrode terminal 15 and the negative electrode terminal 16, respectively.

図２及び図４（ａ）に示すように、電極組立体１２は、第１の電極としての正極電極２０と、第２の電極としての負極電極２１と、セパレータ３０とを複数備える。電極組立体１２は、正極電極２０と負極電極２１との間にセパレータ３０を介在させ、かつ相互に絶縁させた状態で積層した構造を備える。 As shown in FIGS. 2 and 4A, the electrode assembly 12 includes a plurality of positive electrode electrodes 20 as first electrodes, negative electrode 21 as second electrodes, and a plurality of separators 30. The electrode assembly 12 has a structure in which a separator 30 is interposed between the positive electrode 20 and the negative electrode 21 and is laminated in a state of being insulated from each other.

正極電極２０は、矩形シート状の集電体としての正極金属箔（例えばアルミニウム箔）２２と、正極金属箔２２の両面に存在する正極活物質層２３とを有する。正極金属箔２２は、正極電極２０の外形を構成する。正極活物質層２３は、活物質、導電助剤、溶媒及びバインダを混合した活物質ペーストを正極金属箔２２に塗布した後、乾燥させることで形成される。正極電極２０は、一対の長辺に沿う縁部のうちの一方の縁部に第１縁部２０ａを備える。正極電極２０は、第１縁部２０ａの一部から突出した形状のタブとしての正極タブ２４を有する。正極タブ２４は、正極活物質層２３が存在せず、正極金属箔２２そのもので構成されている。 The positive electrode electrode 20 has a positive electrode metal foil (for example, an aluminum foil) 22 as a current collector in the shape of a rectangular sheet, and a positive electrode active material layer 23 existing on both sides of the positive electrode metal foil 22. The positive electrode metal leaf 22 constitutes the outer shape of the positive electrode 20. The positive electrode active material layer 23 is formed by applying an active material paste, which is a mixture of an active material, a conductive additive, a solvent, and a binder, to the positive electrode metal foil 22 and then drying it. The positive electrode 20 includes a first edge portion 20a on one edge portion of the edge portions along a pair of long sides. The positive electrode electrode 20 has a positive electrode tab 24 as a tab having a shape protruding from a part of the first edge portion 20a. The positive electrode tab 24 does not have the positive electrode active material layer 23 and is composed of the positive electrode metal foil 22 itself.

また、正極電極２０は、一対の長辺に沿う縁部のうちの第１縁部２０ａの対辺となる他方の縁部に第２縁部２０ｂを備える。さらに、正極電極２０は、第１縁部２０ａと第２縁部２０ｂ同士を繋ぐ一対の短辺に沿う縁部のうちの一方の縁部に第３縁部２０ｃを備え、第３縁部２０ｃの対辺となる他方の縁部に第４縁部２０ｄを備える。正極活物質層２３の縁部は、正極電極２０の第１〜第４縁部２０ａ〜２０ｄと一致する。つまり、正極活物質層２３は、正極タブ２４を除く正極金属箔２２全体を覆っている。 Further, the positive electrode electrode 20 includes a second edge portion 20b on the other edge portion which is the opposite side of the first edge portion 20a among the edge portions along the pair of long sides. Further, the positive electrode 20 includes a third edge portion 20c on one edge portion of one of the edge portions along the pair of short sides connecting the first edge portion 20a and the second edge portion 20b, and the third edge portion 20c. A fourth edge portion 20d is provided on the other edge portion which is the opposite side of the above. The edge portion of the positive electrode active material layer 23 coincides with the first to fourth edge portions 20a to 20d of the positive electrode electrode 20. That is, the positive electrode active material layer 23 covers the entire positive electrode metal foil 22 except for the positive electrode tab 24.

負極電極２１は、矩形シート状の集電体としての負極金属箔（例えば銅箔）２５と、負極金属箔２５の両面に存在する負極活物質層２６とを有する。負極金属箔２５は、負極電極２１の外形を構成する。負極活物質層２６は、活物質、導電助剤、溶媒及びバインダを混合した活物質ペーストを負極金属箔２５に塗布した後、乾燥させることで形成される。本実施形態の活物質はシリコンであり、負極活物質層２６はケイ素を含む。活物質にシリコン（ケイ素）を用いることで、例えばカーボンを用いる場合と比較して、二次電池１０の容量を増大させることができる。一方で、ケイ素を含む負極活物質層２６は、二次電池１０の充放電時に膨張収縮しやすい。負極電極２１は、一対の長辺に沿う縁部のうちの一方の縁部に第１縁部２１ａを備える。負極電極２１は、第１縁部２１ａの一部から突出した形状のタブとしての負極タブ２７を有する。負極タブ２７は、負極活物質層２６が存在せず、負極金属箔２５そのもので構成されている。 The negative electrode electrode 21 has a negative electrode metal foil (for example, a copper foil) 25 as a rectangular sheet-shaped current collector, and a negative electrode active material layer 26 existing on both sides of the negative electrode metal foil 25. The negative electrode metal foil 25 constitutes the outer shape of the negative electrode electrode 21. The negative electrode active material layer 26 is formed by applying an active material paste, which is a mixture of an active material, a conductive auxiliary agent, a solvent, and a binder, to the negative electrode metal foil 25 and then drying the negative electrode active material layer 26. The active material of the present embodiment is silicon, and the negative electrode active material layer 26 contains silicon. By using silicon as the active material, the capacity of the secondary battery 10 can be increased as compared with the case where carbon is used, for example. On the other hand, the negative electrode active material layer 26 containing silicon tends to expand and contract during charging and discharging of the secondary battery 10. The negative electrode electrode 21 includes a first edge portion 21a on one edge portion of the edge portions along the pair of long sides. The negative electrode electrode 21 has a negative electrode tab 27 as a tab having a shape protruding from a part of the first edge portion 21a. The negative electrode tab 27 does not have the negative electrode active material layer 26 and is composed of the negative electrode metal foil 25 itself.

また、負極電極２１は、一対の長辺に沿う縁部のうちの第１縁部２１ａの対辺となる他方の縁部に他の縁部としての第２縁部２１ｂを備える。さらに、負極電極２１は、第１縁部２１ａと第２縁部２１ｂ同士を繋ぐ一対の短辺に沿う縁部のうちの一方の縁部に他の縁部としての第３縁部２１ｃを備え、第３縁部２１ｃの対辺となる他方の縁部に他の縁部としての第４縁部２１ｄを備える。 Further, the negative electrode electrode 21 includes a second edge portion 21b as another edge portion on the other edge portion which is the opposite side of the first edge portion 21a among the edge portions along the pair of long sides. Further, the negative electrode electrode 21 includes a third edge portion 21c as another edge portion at one edge portion of the edge portions along the pair of short sides connecting the first edge portion 21a and the second edge portion 21b. , The other edge portion opposite to the third edge portion 21c is provided with a fourth edge portion 21d as another edge portion.

負極電極２１の第１縁部２１ａの長さは、正極電極２０の第１縁部２０ａの長さより長く、負極電極２１の第２縁部２１ｂの長さは、正極電極２０の第２縁部２０ｂの長さより長い。さらに、負極電極２１の第３縁部２１ｃの長さは、正極電極２０の第３縁部２０ｃの長さより長く、負極電極２１の第４縁部２１ｄの長さは、正極電極２０の第４縁部２０ｄの長さより長い。よって、負極電極２１の外形は、正極電極２０の外形より一回り大きい。なお、セパレータ３０の外形は、負極電極２１の外形と同じ大きさである。 The length of the first edge portion 21a of the negative electrode electrode 21 is longer than the length of the first edge portion 20a of the positive electrode electrode 20, and the length of the second edge portion 21b of the negative electrode electrode 21 is the length of the second edge portion 20 of the positive electrode electrode 20. It is longer than the length of 20b. Further, the length of the third edge portion 21c of the negative electrode electrode 21 is longer than the length of the third edge portion 20c of the positive electrode electrode 20, and the length of the fourth edge portion 21d of the negative electrode electrode 21 is the length of the fourth edge portion 21d of the positive electrode electrode 20. It is longer than the length of the edge 20d. Therefore, the outer shape of the negative electrode 21 is one size larger than the outer shape of the positive electrode 20. The outer shape of the separator 30 is the same size as the outer shape of the negative electrode 21.

以下、負極電極２１の面と直交する方向を厚さ方向Ｘとし、負極電極２１の面に沿う方向を面方向Ｙとする。面方向Ｙは、第１及び第２縁部２１ａ，２１ｂと直交する第１方向Ｙ１と、第３及び第４縁部２１ｃ，２１ｄと直交する第２方向Ｙ２とを有する。 Hereinafter, the direction orthogonal to the surface of the negative electrode electrode 21 is defined as the thickness direction X, and the direction along the surface of the negative electrode electrode 21 is defined as the surface direction Y. The plane direction Y has a first direction Y1 orthogonal to the first and second edge portions 21a and 21b, and a second direction Y2 orthogonal to the third and fourth edge portions 21c and 21d.

図３に示すように、負極電極２１は、第２〜第４縁部２１ｂ〜２１ｄに沿って負極金属箔２５の露出した未塗工部２８を備える。未塗工部２８は、負極金属箔２５において負極活物質層２６が存在せず、負極金属箔２５そのもので構成された部分である。第２縁部２１ｂに沿って存在する未塗工部２８を第１未塗工部２８ａとし、第３縁部２１ｃに沿って存在する未塗工部２８を第２未塗工部２８ｂとし、第４縁部２１ｄに沿って存在する未塗工部２８を第３未塗工部２８ｃとする。なお、第１縁部２１ａの第２方向Ｙ２の一端部には第２未塗工部２８ｂの一部が存在し、他端部には第３未塗工部２８ｃの一部が存在し、中央部には負極活物質層２６が存在する。 As shown in FIG. 3, the negative electrode electrode 21 includes an exposed uncoated portion 28 of the negative electrode metal foil 25 along the second to fourth edge portions 21b to 21d. The uncoated portion 28 is a portion of the negative electrode metal foil 25 in which the negative electrode active material layer 26 does not exist and is composed of the negative electrode metal foil 25 itself. The uncoated portion 28 existing along the second edge portion 21b is referred to as the first uncoated portion 28a, and the uncoated portion 28 existing along the third edge portion 21c is referred to as the second uncoated portion 28b. The uncoated portion 28 existing along the fourth edge portion 21d is referred to as the third uncoated portion 28c. A part of the second uncoated portion 28b is present at one end of the first edge portion 21a in the second direction Y2, and a part of the third uncoated portion 28c is present at the other end. The negative electrode active material layer 26 is present in the central portion.

負極電極２１は、負極活物質層２６と未塗工部２８との境界部２９を備える。負極活物質層２６の縁部は境界部２９と一致する。負極活物質層２６と第１未塗工部２８ａとの境界部２９を第１境界部２９ａとする。第１境界部２９ａは、第２縁部２１ｂと平行に存在する。よって、第１未塗工部２８ａの第１方向Ｙ１に沿う寸法Ａ１は、第２方向Ｙ２に沿う第１未塗工部２８ａ全体で同じである。負極活物質層２６と第２未塗工部２８ｂとの境界部２９を第２境界部２９ｂとする。第２境界部２９ｂは、第３縁部２１ｃと平行に存在する。よって、第２未塗工部２８ｂの第２方向Ｙ２に沿う寸法Ａ２は、第１方向Ｙ１に沿う第２未塗工部２８ｂ全体で同じである。負極活物質層２６と第３未塗工部２８ｃとの境界部２９を第３境界部２９ｃとする。第３境界部２９ｃは、第４縁部２１ｄと平行に存在する。よって、第３未塗工部２８ｃの第２方向Ｙ２に沿う寸法Ａ３は、第１方向Ｙ１に沿う第３未塗工部２８ｃ全体で同じである。本実施形態では、第１〜第３未塗工部２８ａ〜２８ｃの寸法Ａ１〜Ａ３は同じ寸法に設定されている。第１〜第３未塗工部２８ａ〜２８ｃの寸法Ａ１〜Ａ３は、負極金属箔２５及び負極金属箔２５の両面に存在する負極活物質層２６の厚さ方向Ｘの寸法Ｂ（図４（ａ）参照）、すなわち負極電極２１の厚みよりも大きい。 The negative electrode electrode 21 includes a boundary portion 29 between the negative electrode active material layer 26 and the uncoated portion 28. The edge of the negative electrode active material layer 26 coincides with the boundary portion 29. The boundary portion 29 between the negative electrode active material layer 26 and the first uncoated portion 28a is designated as the first boundary portion 29a. The first boundary portion 29a exists in parallel with the second edge portion 21b. Therefore, the dimension A1 of the first uncoated portion 28a along the first direction Y1 is the same for the entire first uncoated portion 28a along the second direction Y2. The boundary portion 29 between the negative electrode active material layer 26 and the second uncoated portion 28b is referred to as a second boundary portion 29b. The second boundary portion 29b exists in parallel with the third edge portion 21c. Therefore, the dimension A2 of the second uncoated portion 28b along the second direction Y2 is the same for the entire second uncoated portion 28b along the first direction Y1. The boundary portion 29 between the negative electrode active material layer 26 and the third uncoated portion 28c is designated as the third boundary portion 29c. The third boundary portion 29c exists in parallel with the fourth edge portion 21d. Therefore, the dimension A3 of the third uncoated portion 28c along the second direction Y2 is the same for the entire third uncoated portion 28c along the first direction Y1. In the present embodiment, the dimensions A1 to A3 of the first to third uncoated portions 28a to 28c are set to the same dimensions. Dimensions A1 to A3 of the first to third uncoated portions 28a to 28c are dimensions B in the thickness direction X of the negative electrode active material layer 26 existing on both sides of the negative electrode metal foil 25 and the negative electrode metal foil 25 (FIG. 4 (FIG. 4). a)), that is, it is larger than the thickness of the negative electrode 21.

図１に示すように、各正極電極２０は、それぞれの正極タブ２４が電極組立体１２の積層方向に沿って列状に配置されるように積層される。同様に、各負極電極２１は、それぞれの負極タブ２７が、正極タブ２４と重ならないように電極組立体１２の積層方向に沿って列状に配置されるように積層される。そして、各正極タブ２４は、電極組立体１２における積層方向の一端から他端までの範囲に集められて正極タブ群２４ａとされる。正極タブ群２４ａには、正極端子１５が電気的に接合される。また、各負極タブ２７も同様に、電極組立体１２における積層方向の一端から他端までの範囲に集められて負極タブ群２７ａとされる。負極タブ群２７ａには、負極端子１６が電気的に接続される。 As shown in FIG. 1, the positive electrode electrodes 20 are laminated so that the positive electrode tabs 24 are arranged in a row along the stacking direction of the electrode assembly 12. Similarly, the negative electrode electrodes 21 are laminated so that the negative electrode tabs 27 are arranged in a row along the stacking direction of the electrode assembly 12 so that the negative electrode tabs 27 do not overlap with the positive electrode tabs 24. Then, the positive electrode tabs 24 are gathered in the range from one end to the other end in the stacking direction in the electrode assembly 12 to form a positive electrode tab group 24a. The positive electrode terminal 15 is electrically joined to the positive electrode tab group 24a. Similarly, the negative electrode tabs 27 are also gathered in the range from one end to the other end in the stacking direction in the electrode assembly 12 to form a negative electrode tab group 27a. The negative electrode terminal 16 is electrically connected to the negative electrode tab group 27a.

電極組立体１２は、蓋１４に対向した端面にタブ側端面１２ａを備え、ケース本体１３の底壁１３ｂの内面に対向した端面に底側端面１２ｂを備える。タブ側端面１２ａは、負極電極２１の第１縁部２１ａが積層されて構成されている。底側端面１２ｂは、負極電極２１の第２縁部２１ｂ（第１未塗工部２８ａ）が積層されて構成されている。また、電極組立体１２は、ケース本体１３の第１壁部１３ｃの内面に対向した端面に第１側面１２ｃを備え、ケース本体１３の第２壁部１３ｄの内面に対向した端面に第２側面１２ｄを備える。電極組立体１２は、ケース本体１３の第３壁部１３ｅの内面に対向した端面に第３側面１２ｅを備え、ケース本体１３の第４壁部１３ｆの内面に対向した端面に第４側面１２ｆを備える。第３側面１２ｅは、負極電極２１の第３縁部２１ｃ（第２未塗工部２８ｂ）が積層されて構成され、第４側面１２ｆは、負極電極２１の第４縁部２１ｄ（第３未塗工部２８ｃ）が積層されて構成されている。 The electrode assembly 12 includes a tab-side end surface 12a on the end surface facing the lid 14, and a bottom-side end surface 12b on the end surface facing the inner surface of the bottom wall 13b of the case body 13. The tab side end surface 12a is configured by laminating the first edge portion 21a of the negative electrode electrode 21. The bottom end surface 12b is configured by laminating a second edge portion 21b (first uncoated portion 28a) of the negative electrode electrode 21. Further, the electrode assembly 12 is provided with a first side surface 12c on an end surface facing the inner surface of the first wall portion 13c of the case body 13, and a second side surface on the end surface facing the inner surface of the second wall portion 13d of the case body 13. 12d is provided. The electrode assembly 12 includes a third side surface 12e on an end surface of the case body 13 facing the inner surface of the third wall portion 13e, and a fourth side surface 12f on the end surface of the case body 13 facing the inner surface of the fourth wall portion 13f. Be prepared. The third side surface 12e is formed by laminating the third edge portion 21c (second uncoated portion 28b) of the negative electrode electrode 21, and the fourth side surface 12f is formed by the fourth edge portion 21d (third uncoated portion 28b) of the negative electrode electrode 21. The coating portion 28c) is laminated.

図３に示すように、電極組立体１２を積層方向から見たとき、正極電極２０の第１縁部２０ａは、第１方向Ｙ１において負極電極２１の第１縁部２１ａよりも内側に位置し、正極電極２０の第２縁部２０ｂは、第１方向Ｙ１において負極電極２１の第２縁部２１ｂよりも内側に位置する。また、正極電極２０の第３縁部２０ｃは、第２方向Ｙ２において負極電極２１の第３縁部２１ｃよりも内側に位置し、正極電極２０の第４縁部２０ｄは、第２方向Ｙ２において負極電極２１の第４縁部２１ｄよりも内側に位置する。 As shown in FIG. 3, when the electrode assembly 12 is viewed from the stacking direction, the first edge portion 20a of the positive electrode electrode 20 is located inside the first edge portion 21a of the negative electrode electrode 21 in the first direction Y1. The second edge portion 20b of the positive electrode electrode 20 is located inside the second edge portion 21b of the negative electrode electrode 21 in the first direction Y1. Further, the third edge portion 20c of the positive electrode 20 is located inside the third edge portion 21c of the negative electrode electrode 21 in the second direction Y2, and the fourth edge portion 20d of the positive electrode electrode 20 is located in the second direction Y2. It is located inside the fourth edge portion 21d of the negative electrode electrode 21.

このような電極組立体１２は、絶縁シートとしての絶縁フィルム４０で覆われている。絶縁フィルム４０は、電極組立体１２を金属製のケース１１と絶縁するための絶縁性シートであり、例えば、ポリプロピレン（ＰＰ）製である。絶縁フィルム４０は、１枚の絶縁フィルム４０を折り畳み、かつ溶着して袋状に形成されている。絶縁フィルム４０は、電極組立体１２のタブ側端面１２ａを除く５面（底側端面１２ｂ及び第１〜第４側面１２ｃ〜１２ｆ）を覆っている。負極電極２１の第２〜第４縁部２１ｂ〜２１ｄ及びセパレータ３０の縁部は、絶縁フィルム４０と当接している。 Such an electrode assembly 12 is covered with an insulating film 40 as an insulating sheet. The insulating film 40 is an insulating sheet for insulating the electrode assembly 12 from the metal case 11, and is made of polypropylene (PP), for example. The insulating film 40 is formed in a bag shape by folding and welding one insulating film 40. The insulating film 40 covers five surfaces (bottom side end surface 12b and first to fourth side surfaces 12c to 12f) excluding the tab side end surface 12a of the electrode assembly 12. The second to fourth edge portions 21b to 21d of the negative electrode electrode 21 and the edge portion of the separator 30 are in contact with the insulating film 40.

次に、本実施形態の作用について説明する。
二次電池１０の充放電を行うと、正極電極２０の正極活物質層２３及び負極電極２１の負極活物質層２６は、面方向Ｙ外側に膨張したり、面方向Ｙ内側に収縮したりする。なお、正極活物質層２３及び負極活物質層２６は厚さ方向Ｘにも膨張収縮しようとするが、一般に二次電池１０の充放電は、図示しない拘束治具によって電極組立体１２を厚さ方向Ｘに拘束した状態で行われるため、厚さ方向Ｘ外側への膨張量及び厚さ方向Ｘ内側への収縮量は十分小さい。正極活物質層２３及び負極活物質層２６の膨張に伴い、正極電極２０の正極金属箔２２及び負極電極２１の負極金属箔２５も面方向Ｙ外側に膨張する。負極電極２１の第１縁部２１ａ及び第２縁部２１ｂは、第１方向Ｙ１外側へ膨張し、第３縁部２１ｃ及び第４縁部２１ｄは、第２方向Ｙ２外側へ膨張する。 Next, the operation of this embodiment will be described.
When the secondary battery 10 is charged and discharged, the positive electrode active material layer 23 of the positive electrode 20 and the negative electrode active material layer 26 of the negative electrode electrode 21 expand outward in the plane direction Y or contract inward in the plane direction Y. .. The positive electrode active material layer 23 and the negative electrode active material layer 26 try to expand and contract in the thickness direction X as well, but in general, charging and discharging of the secondary battery 10 causes the electrode assembly 12 to be thickened by a restraint jig (not shown). Since the operation is performed in a state of being constrained in the direction X, the amount of expansion outward in the thickness direction X and the amount of contraction inward the thickness direction X are sufficiently small. As the positive electrode active material layer 23 and the negative electrode active material layer 26 expand, the positive electrode metal foil 22 of the positive electrode 20 and the negative electrode metal foil 25 of the negative electrode 21 also expand outward in the plane direction Y. The first edge portion 21a and the second edge portion 21b of the negative electrode electrode 21 expand outward in the first direction Y1, and the third edge portion 21c and the fourth edge portion 21d expand outward in the second direction Y2.

これにより、負極電極２１の第２〜第４縁部２１ｂ〜２１ｄは、絶縁フィルム４０をケース本体１３側へ押圧する。しかしながら、第２〜第４縁部２１ｂ〜２１ｄに沿って負極金属箔２５が露出した第１〜第３未塗工部２８ａ〜２８ｃが存在するため、負極活物質層２６が存在する他の部分と比べて剛性が低い。よって、第２〜第４縁部２１ｂ〜２１ｄに沿う部分は、図４（ｂ）に示すように折れ曲がる。折れ曲がった部分は、第１〜第３境界部２９ａ〜２９ｃ、すなわち負極活物質層２６の縁部を厚さ方向Ｘに覆った状態となる。 As a result, the second to fourth edge portions 21b to 21d of the negative electrode electrode 21 press the insulating film 40 toward the case body 13. However, since the first to third uncoated portions 28a to 28c in which the negative electrode metal foil 25 is exposed are present along the second to fourth edge portions 21b to 21d, the other portion in which the negative electrode active material layer 26 is present. Rigidity is low compared to. Therefore, the portion along the second to fourth edge portions 21b to 21d is bent as shown in FIG. 4 (b). The bent portion covers the first to third boundary portions 29a to 29c, that is, the edge portion of the negative electrode active material layer 26 in the thickness direction X.

また、第１未塗工部２８ａの第１方向Ｙ１に沿う寸法Ａ１は、第２方向Ｙ２に沿う第２縁部２１ｂ全体で同じである。このため、第２縁部２１ｂに沿う部分の第１方向Ｙ１外側への膨張量は、第２方向Ｙ２に沿う第２縁部２１ｂ全体でほぼ同じになる。同様に、第２及び第３未塗工部２８ｂ，２８ｃの第２方向Ｙ２に沿う寸法Ａ２，Ａ３は、第１方向Ｙ１に沿う第３及び第４縁部２１ｃ，２１ｄ全体で同じである。このため、第３縁部２１ｃに沿う部分の第２方向Ｙ２外側への膨張量は、第１方向Ｙ１に沿う第３縁部２１ｃ全体でほぼ同じになる。また、第４縁部２１ｄに沿う部分の第２方向Ｙ２外側への膨張量は、第１方向Ｙ１に沿う第４縁部２１ｄ全体でほぼ同じになる。よって、絶縁フィルム４０は、第２〜第４縁部２１ｂ〜２１ｄ全体によってケース本体１３側に押圧されるため、第２〜第４縁部２１ｂ〜２１ｄの一部によって押圧される場合と比べて、絶縁フィルム４０にかかる荷重が分散される。 Further, the dimension A1 of the first uncoated portion 28a along the first direction Y1 is the same for the entire second edge portion 21b along the second direction Y2. Therefore, the amount of expansion of the portion along the second edge portion 21b to the outside in the first direction Y1 is substantially the same for the entire second edge portion 21b along the second direction Y2. Similarly, the dimensions A2 and A3 of the second and third uncoated portions 28b and 28c along the second direction Y2 are the same for the entire third and fourth edge portions 21c and 21d along the first direction Y1. Therefore, the amount of expansion of the portion along the third edge portion 21c to the outside in the second direction Y2 is substantially the same for the entire third edge portion 21c along the first direction Y1. Further, the amount of expansion of the portion along the fourth edge portion 21d to the outside of the second direction Y2 is substantially the same for the entire fourth edge portion 21d along the first direction Y1. Therefore, since the insulating film 40 is pressed toward the case body 13 by the entire second to fourth edge portions 21b to 21d, compared with the case where the insulating film 40 is pressed by a part of the second to fourth edge portions 21b to 21d. , The load applied to the insulating film 40 is dispersed.

次に、本実施形態の効果を記載する。
（１）二次電池１０の充放電を行うと、正極電極２０及び負極電極２１は、面方向外側へ膨張したり面方向内側へ収縮したりする。第１方向Ｙ１外側へ膨張する負極電極２１の第２縁部２１ｂと第２方向Ｙ２外側へ膨張する負極電極２１の第３及び第４縁部２１ｃ，２１ｄは、絶縁フィルム４０を押圧する。しかしながら、第２〜第４縁部２１ｂ〜２１ｄに沿って負極金属箔２５が露出した第１〜第３未塗工部２８ａ〜２８ｃが存在するため、負極活物質層２６が存在する他の部分と比べて剛性が低い。よって、負極電極２１において第２〜第４縁部２１ｂ〜２１ｄに沿う部分は折れ曲がる。 Next, the effect of this embodiment will be described.
(1) When the secondary battery 10 is charged and discharged, the positive electrode 20 and the negative electrode 21 expand outward in the plane direction and contract inward in the plane direction. The second edge 21b of the negative electrode 21 expanding outward in the first direction Y1 and the third and fourth edges 21c and 21d of the negative electrode 21 expanding outward in the second direction Y2 press the insulating film 40. However, since the first to third uncoated portions 28a to 28c in which the negative electrode metal foil 25 is exposed are present along the second to fourth edge portions 21b to 21d, the other portion in which the negative electrode active material layer 26 is present. Rigidity is low compared to. Therefore, in the negative electrode electrode 21, the portion along the second to fourth edge portions 21b to 21d is bent.

また、第１〜第３境界部２９ａ〜２９ｃは、第２〜第４縁部２１ｂ〜２１ｄと平行に存在する。このため、第２縁部２１ｂに沿う部分の第１方向Ｙ１外側への膨張量は、第２方向Ｙ２に沿う第２縁部２１ｂ全体でほぼ同じになり、第３及び第４縁部２１ｃ，２１ｄに沿う部分の第２方向Ｙ２外側への膨張量は、第１方向Ｙ１に沿う第３及び第４縁部２１ｃ，２１ｄ全体でほぼ同じになる。よって、絶縁フィルム４０は、第２〜第４縁部２１ｂ〜２１ｄ全体によって押圧されるため、第２〜第４縁部２１ｂ〜２１ｄの一部によって押圧される場合と比べて、絶縁フィルム４０にかかる荷重を分散できる。その結果、負極電極２１の膨張による絶縁フィルム４０の破れを抑制できる。 Further, the first to third boundary portions 29a to 29c exist in parallel with the second to fourth edge portions 21b to 21d. Therefore, the amount of expansion of the portion along the second edge portion 21b to the outside in the first direction Y1 is substantially the same for the entire second edge portion 21b along the second direction Y2, and the third and fourth edge portions 21c, The amount of expansion of the portion along the 21d to the outside of the second direction Y2 is substantially the same for the entire third and fourth edge portions 21c and 21d along the first direction Y1. Therefore, since the insulating film 40 is pressed by the entire second to fourth edge portions 21b to 21d, the insulating film 40 is pressed by a part of the second to fourth edge portions 21b to 21d as compared with the case where the insulating film 40 is pressed by a part of the second to fourth edge portions 21b to 21d. The load can be dispersed. As a result, the tearing of the insulating film 40 due to the expansion of the negative electrode electrode 21 can be suppressed.

（２）第１未塗工部２８ａの第１方向Ｙ１に沿う寸法Ａ１は、負極電極２１（負極金属箔２５及び負極金属箔２５の両面に存在する負極活物質層２６）の厚さ方向Ｘの寸法Ｂよりも大きい。また、第２及び第３未塗工部２８ｂ，２８ｃの第２方向Ｙ２に沿う寸法Ａ２，Ａ３は、負極電極２１（負極金属箔２５及び負極金属箔２５の両面に存在する負極活物質層２６）の厚さ方向Ｘの寸法Ｂよりも大きい。このため、折れ曲がった第１〜第３未塗工部２８ａ〜２８ｃは、第１〜第３境界部２９ａ〜２９ｃ、すなわち負極活物質層２６の縁部を厚さ方向Ｘに覆った状態となる。よって、折れ曲がった第１〜第３未塗工部２８ａ〜２８ｃにより、負極活物質層２６を絶縁フィルム４０に接触させないようにでき、負極電極２１の膨張による絶縁フィルム４０の破れをより抑制できる。 (2) The dimension A1 along the first direction Y1 of the first uncoated portion 28a is the thickness direction X of the negative electrode electrode 21 (the negative electrode active material layer 26 existing on both sides of the negative electrode metal foil 25 and the negative electrode metal foil 25). Is larger than the dimension B of. Further, the dimensions A2 and A3 of the second and third uncoated portions 28b and 28c along the second direction Y2 are the negative electrode electrodes 21 (negative electrode active material layers 26 existing on both sides of the negative electrode metal foil 25 and the negative electrode metal foil 25). ) Is larger than the dimension B in the thickness direction X. Therefore, the bent first to third uncoated portions 28a to 28c are in a state of covering the first to third boundary portions 29a to 29c, that is, the edge portion of the negative electrode active material layer 26 in the thickness direction X. .. Therefore, the bent first to third uncoated portions 28a to 28c can prevent the negative electrode active material layer 26 from coming into contact with the insulating film 40, and the tearing of the insulating film 40 due to the expansion of the negative electrode electrode 21 can be further suppressed.

（３）負極電極２１の負極活物質層２６はケイ素を含む。ケイ素を含む負極活物質層２６の膨張率は、ケイ素を含まない負極活物質層の膨張率よりも大きいため、負極電極２１の膨張による絶縁フィルム４０の破れが発生しやすい。このため、負極活物質層２６にケイ素を含む負極電極２１の第２〜第４縁部２１ｂ〜２１ｄに沿って未塗工部２８を設けることで、負極電極２１の膨張による絶縁フィルム４０の破れを抑制できる。 (3) The negative electrode active material layer 26 of the negative electrode electrode 21 contains silicon. Since the expansion coefficient of the negative electrode active material layer 26 containing silicon is larger than the expansion coefficient of the negative electrode active material layer containing no silicon, the insulating film 40 is likely to be torn due to the expansion of the negative electrode electrode 21. Therefore, by providing the uncoated portion 28 along the second to fourth edge portions 21b to 21d of the negative electrode electrode 21 containing silicon in the negative electrode active material layer 26, the insulating film 40 is torn due to the expansion of the negative electrode electrode 21. Can be suppressed.

なお、上記実施形態は、以下のように変更してもよい。
○ 集電体は、正極活物質層２３や負極活物質層２６が形成できるものであれば、正極金属箔２２や負極金属箔２５に限定されるものではない。例えば、織物状や網状のシートを用いてもよい。 The above embodiment may be changed as follows.
○ The current collector is not limited to the positive electrode metal foil 22 and the negative electrode metal foil 25 as long as the positive electrode active material layer 23 and the negative electrode active material layer 26 can be formed. For example, a woven or net-like sheet may be used.

○ 正極電極２０は、正極金属箔２２の片面に正極活物質層２３が存在する構造でもよい。同様に、負極電極２１は、負極金属箔２５の片面に負極活物質層２６が存在する構成でもよい。 ○ The positive electrode electrode 20 may have a structure in which the positive electrode active material layer 23 exists on one side of the positive electrode metal foil 22. Similarly, the negative electrode electrode 21 may have a configuration in which the negative electrode active material layer 26 is present on one side of the negative electrode metal foil 25.

○ 正極電極２０は、正極タブ２４以外に正極活物質層２３が存在しない部分を備えていてもよい。
○ 負極電極２１は、負極タブ２７及び未塗工部２８以外に負極活物質層２６が存在しない部分を備えていてもよい。例えば、負極電極２１は、第１縁部２１ａに沿って未塗工部２８を備えていてもよい。 ○ The positive electrode electrode 20 may include a portion other than the positive electrode tab 24 where the positive electrode active material layer 23 does not exist.
○ The negative electrode electrode 21 may include a portion where the negative electrode active material layer 26 does not exist other than the negative electrode tab 27 and the uncoated portion 28. For example, the negative electrode 21 may include an uncoated portion 28 along the first edge portion 21a.

○ 第１の電極を負極電極２１とし、第２の電極を正極電極２０としてもよい。この場合、正極電極２０の第２〜第４縁部２０ｂ〜２０ｄに沿って正極活物質層２３が存在せず正極金属箔２２の露出した未塗工部を設ける。 ○ The first electrode may be the negative electrode 21, and the second electrode may be the positive electrode 20. In this case, the positive electrode active material layer 23 does not exist along the second to fourth edge portions 20b to 20d of the positive electrode electrode 20, and an exposed uncoated portion of the positive electrode metal foil 22 is provided.

○ 第１未塗工部２８ａの第１方向Ｙ１に沿う寸法Ａ１は、負極電極２１（負極金属箔２５及び負極金属箔２５の両面に存在する負極活物質層２６）の厚さ方向Ｘの寸法Ｂより小さくてもよいし、同じでもよい。同様に、第２及び第３未塗工部２８ｂ，２８ｃの第２方向Ｙ２に沿う寸法Ａ２，Ａ３は、負極電極２１（負極金属箔２５及び負極金属箔２５の両面に存在する負極活物質層２６）の厚さ方向Ｘの寸法Ｂより小さくてもよいし、同じでもよい。 ○ The dimension A1 along the first direction Y1 of the first uncoated portion 28a is the dimension X in the thickness direction of the negative electrode 21 (the negative electrode active material layer 26 existing on both sides of the negative electrode metal foil 25 and the negative electrode metal foil 25). It may be smaller than B or the same. Similarly, the dimensions A2 and A3 of the second and third uncoated portions 28b and 28c along the second direction Y2 are the negative electrode active material layers existing on both sides of the negative electrode electrode 21 (negative electrode metal foil 25 and negative electrode metal foil 25). It may be smaller than or the same as the dimension B in the thickness direction X of 26).

○ 負極活物質層２６の活物質は、カーボンでもよく、シリコンとカーボンの両方を含んでもよい。活物質に用いる材料の種類や割合は、二次電池１０の容量に応じて変更してよい。 ○ The active material of the negative electrode active material layer 26 may be carbon or may contain both silicon and carbon. The type and proportion of the material used for the active material may be changed according to the capacity of the secondary battery 10.

○ 絶縁シートの種類は、絶縁フィルム４０に限定されず、ラミネートシートであってもよい。
○ 絶縁フィルム４０の材料は、ポリプロピレン（ＰＰ）に限定されず、ポリフェニレンサルファイド（ＰＰＳ）など他の材料でもよい。 ○ The type of the insulating sheet is not limited to the insulating film 40, and may be a laminated sheet.
○ The material of the insulating film 40 is not limited to polypropylene (PP), and other materials such as polyphenylene sulfide (PPS) may be used.

○ 複数枚の絶縁フィルム４０によって電極組立体１２を覆う構成としてもよい。
○ 絶縁フィルム４０を袋状に形成する方法は、溶着に限定されない。例えば、絶縁フィルム４０によって電極組立体１２を覆った後、電極組立体１２からはみ出した部分を、電極組立体１２を覆っている部分に重ねてテープで貼り付けてもよい。また、他の方法として、電極組立体１２より一回り大きい袋状の絶縁フィルム４０の中に電極組立体１２を収納し、その後で絶縁フィルム４０を熱収縮させることで電極組立体１２と絶縁フィルム４０とを密着させてもよい。 O The electrode assembly 12 may be covered with a plurality of insulating films 40.
○ The method of forming the insulating film 40 in a bag shape is not limited to welding. For example, after covering the electrode assembly 12 with the insulating film 40, the portion protruding from the electrode assembly 12 may be overlapped with the portion covering the electrode assembly 12 and attached with tape. As another method, the electrode assembly 12 is housed in a bag-shaped insulating film 40 that is one size larger than the electrode assembly 12, and then the insulating film 40 is heat-shrinked to obtain the electrode assembly 12 and the insulating film. It may be brought into close contact with 40.

○ 二次電池１０は、リチウムイオン二次電池でもよいし、他の二次電池であってもよい。要は、正極用の活物質と負極用の活物質との間をイオンが移動するとともに電荷の授受を行うものであればよい。 ○ The secondary battery 10 may be a lithium ion secondary battery or another secondary battery. In short, it suffices as long as the ions move between the active material for the positive electrode and the active material for the negative electrode and transfer charges.

○ 蓄電装置は、例えばキャパシタなど、二次電池以外の蓄電装置にも適用可能である。
次に、上記実施形態及び別例から把握できる技術的思想を以下に追記する。 ○ The power storage device can also be applied to a power storage device other than a secondary battery, such as a capacitor.
Next, the technical idea that can be grasped from the above embodiment and another example will be added below.

（イ）蓄電装置は二次電池である。 (B) The power storage device is a secondary battery.

１０…蓄電装置としての二次電池、１２…電極組立体、２０…第１の電極としての正極電極、２１…第２の電極としての負極電極、２１ａ…第１縁部、２１ｂ…第２縁部、２１ｃ…第３縁部、２１ｄ…第４縁部、２２…集電体としての正極金属箔、２３…活物質層としての正極活物質層、２４…タブとしての正極タブ、２５…集電体としての負極金属箔、２６…活物質層としての負極活物質層、２７…タブとしての負極タブ、２８…未塗工部、２９…境界部、４０…絶縁シートとしての絶縁フィルム、Ｘ１…厚さ方向、Ｙ…面方向、Ｙ１…第１方向、Ｙ２…第２方向。 10 ... Secondary battery as a power storage device, 12 ... Electrode assembly, 20 ... Positive electrode as the first electrode, 21 ... Negative electrode as the second electrode, 21a ... First edge, 21b ... Second edge Part, 21c ... 3rd edge, 21d ... 4th edge, 22 ... Positive electrode metal foil as current collector, 23 ... Positive electrode active material layer as active material layer, 24 ... Positive electrode tab as tab, 25 ... Collection Negative electrode metal foil as an electric body, 26 ... Negative electrode active material layer as an active material layer, 27 ... Negative electrode tab as a tab, 28 ... Uncoated part, 29 ... Boundary part, 40 ... Insulating film as an insulating sheet, X1 ... thickness direction, Y ... surface direction, Y1 ... first direction, Y2 ... second direction.

Claims (5)

第１の電極と、前記第１の電極と異なる極性であるとともに前記第１の電極の外形よりも大きい外形の第２の電極とをセパレータを介して互いに絶縁した状態で積層した電極組立体と、
前記電極組立体を覆う絶縁シートと、
を備え、
前記第１の電極及び前記第２の電極は、矩形シート状の集電体と、該集電体の片面又は両面に存在する活物質層と、前記集電体の一辺に沿う第１縁部から突出する形状のタブと、を有するとともに、前記第１縁部の対辺である第２縁部と、前記第１縁部と前記第２縁部の一端を繋ぐ第３縁部と、前記第３縁部の対辺である第４縁部とを備え、
前記第２の電極の面に沿う方向を面方向としたとき、積層方向から前記電極組立体を見て、前記第１の電極は、前記第２の電極の第１〜第４縁部よりも前記面方向の内側に位置している蓄電装置であって、
前記第２の電極は、前記第２〜第４縁部に沿って前記活物質層が存在せず前記集電体が露出した未塗工部を有し、前記活物質層と前記未塗工部との境界部は、前記第２〜第４縁部と平行に存在する一方、前記第１縁部には、前記第３縁部に沿って存在する未塗工部と前記活物質層との境界部となる第２境界部の一端と、前記第４縁部に沿って存在する前記活物質層との境界部となる第３境界部の一端と、が位置しており、
前記第１縁部における前記第２境界部と前記第３境界部との間には、前記第１縁部に沿って前記活物質層が存在しており、
前記電極組立体は、前記第１縁部が積層されて構成されたタブ側端面と、前記第２縁部が積層されて構成された底側端面と、前記タブ側端面と前記底側端面を繋ぐ第１〜第４側面とを備え、
前記絶縁シートは、前記タブ側端面を除く前記電極組立体の５面としての前記底側端面と前記第１〜第４側面を覆っていることを特徴とする蓄電装置。 An electrode assembly in which a first electrode and a second electrode having a polarity different from that of the first electrode and having an outer shape larger than the outer shape of the first electrode are laminated in a state of being insulated from each other via a separator. ,
An insulating sheet covering the electrode assembly and
With
The first electrode and the second electrode are a rectangular sheet-shaped current collector, an active material layer existing on one side or both sides of the current collector, and a first edge portion along one side of the current collector. A tab having a shape protruding from the surface, a second edge portion opposite to the first edge portion, a third edge portion connecting the first edge portion and one end of the second edge portion, and the first edge portion. It has a fourth edge, which is the opposite side of the three edges.
When the direction along the surface of the second electrode is the plane direction, the electrode assembly is viewed from the stacking direction, and the first electrode is more than the first to fourth edges of the second electrode. A power storage device located inside in the plane direction.
The second electrode has an uncoated portion in which the active material layer does not exist and the current collector is exposed along the second to fourth edges, and the active material layer and the uncoated portion are provided. The boundary portion with the portion exists in parallel with the second to fourth edge portions, while the first edge portion includes an uncoated portion existing along the third edge portion and the active material layer. One end of the second boundary portion, which is the boundary portion of the above, and one end of the third boundary portion, which is the boundary portion between the active material layer and the active material layer existing along the fourth edge portion, are located.
The active material layer exists along the first edge portion between the second boundary portion and the third boundary portion in the first edge portion.
The electrode assembly includes a tab-side end face formed by laminating the first edge portion, a bottom-side end face formed by laminating the second edge portion, and the tab-side end face and the bottom-side end face. With the first to fourth sides to connect,
The power storage device is characterized in that the insulating sheet covers the bottom end surface and the first to fourth side surfaces as five surfaces of the electrode assembly excluding the tab side end surface. 前記第２〜第４縁部に沿う前記セパレータの縁部は前記絶縁シートと当接する請求項１に記載の蓄電装置。 The power storage device according to claim 1, wherein the edge portion of the separator along the second to fourth edge portions abuts on the insulating sheet. 前記面方向は、前記第１縁部及び前記第２縁部と直交する第１方向と、前記第３縁部及び前記第４縁部と直交する第２方向とを有し、
前記第２縁部に沿って存在する未塗工部の第１方向に沿う寸法、及び前記第３縁部及び前記第４縁部に沿って存在する未塗工部の第２方向に沿う寸法は、それぞれ、前記第２の電極の前記集電体及び前記活物質層の厚さ方向の寸法よりも大きい請求項１又は請求項２に記載の蓄電装置。 The surface direction has a first direction orthogonal to the first edge portion and the second edge portion, and a second direction orthogonal to the third edge portion and the fourth edge portion.
Dimensions along the first direction of the uncoated portion existing along the second edge portion, and dimensions along the second direction of the uncoated portion existing along the third edge portion and the fourth edge portion. The power storage device according to claim 1 or 2, respectively, which is larger than the dimensions of the current collector and the active material layer of the second electrode in the thickness direction. 前記第２の電極は、負極電極である請求項１〜３のいずれか一項に記載の蓄電装置。 The power storage device according to any one of claims 1 to 3, wherein the second electrode is a negative electrode. 前記負極電極の活物質層は、ケイ素を含む請求項４に記載の蓄電装置。 The power storage device according to claim 4 , wherein the active material layer of the negative electrode contains silicon.
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