JP2015216046A - Power storage device - Google Patents

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JP2015216046A
JP2015216046A JP2014098745A JP2014098745A JP2015216046A JP 2015216046 A JP2015216046 A JP 2015216046A JP 2014098745 A JP2014098745 A JP 2014098745A JP 2014098745 A JP2014098745 A JP 2014098745A JP 2015216046 A JP2015216046 A JP 2015216046A
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active material
material layer
thickness
electrode active
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厚志 南形
Atsushi MINAGATA
厚志 南形
元章 奥田
Motoaki Okuda
元章 奥田
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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
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Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which enables the suppression of an internal short circuit caused by an expected foreign material.SOLUTION: A power storage device 1 comprises: a positive electrode 10 having a metal foil 11, and a positive electrode active material layer 12 provided on at least one surface of the metal foil; a negative electrode 20 having a metal foil 21, a negative electrode active material layer 22 provided on at least one surface of the metal foil, and a protection layer 23 provided on the negative electrode active material layer 22; and a separator 30 disposed between the positive electrode 10 and the negative electrode 20. The protection layer 23 is harder than the positive electrode active material layer 12 in hardness. Supposing that of the thickness of the positive electrode active material layer 12 of the thickness of the negative electrode active material layer 22, a larger thickness is P, the hardness of the positive electrode active material layer 12 is x, the hardness of the protection layer 23 is y, the thickness of the protection layer 23 is T, and the thickness of the separator 30 is D, they satisfy the conditions given by: x/(x+y)×(P-D)<T, and P>D.

Description

本発明は、蓄電装置に関する。   The present invention relates to a power storage device.

正極と、負極と、正極と負極との間に介在するセパレータと、電極（正極又は負極）の表面に接着された多孔質絶縁膜とを含む非水電解液二次電池が知られている（例えば特許文献１参照）。   A non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a porous insulating film bonded to the surface of the electrode (positive electrode or negative electrode) is known ( For example, see Patent Document 1).

特許第４８４７８６１号公報Japanese Patent No. 4847861

非水電解液二次電池等の蓄電装置を製造中に、異物（例えば、活物質層から落ちた活物質）がセパレータと電極（正極又は負極）との間に入る場合がある。異物が入った場合、異物によって、まずセパレータが破断し、その後、電極表面の保護層（多孔質絶縁膜）が破断する可能性がある。セパレータ及び保護層の両方が破断すると、正極と負極とが直接又は異物を介して内部短絡する可能性がある。   During manufacturing of a power storage device such as a non-aqueous electrolyte secondary battery, foreign matter (for example, an active material dropped from the active material layer) may enter between the separator and the electrode (positive electrode or negative electrode). When a foreign substance enters, there is a possibility that the separator is first broken by the foreign substance, and then the protective layer (porous insulating film) on the electrode surface is broken. If both the separator and the protective layer are broken, the positive electrode and the negative electrode may be internally short-circuited directly or through foreign matter.

セパレータと電極（正極又は負極）との間に入る最大の異物としては、電極製造工程の打抜き等のときに活物質層から落ちる活物質又は活物質層の一部等が考えられる。よって、保護層の厚み方向における異物の最大サイズは、正極活物質層の厚みと負極活物質層の厚みのうちの厚いほうの厚みと同じであると想定される。   As the largest foreign substance that enters between the separator and the electrode (positive electrode or negative electrode), an active material falling from the active material layer or a part of the active material layer at the time of punching of the electrode manufacturing process or the like can be considered. Therefore, the maximum size of the foreign material in the thickness direction of the protective layer is assumed to be the same as the thicker one of the thickness of the positive electrode active material layer and the thickness of the negative electrode active material layer.

そこで、本発明の一側面は、想定される異物による内部短絡を抑制できる蓄電装置を提供することを目的とする。   In view of the above, an object of one aspect of the present invention is to provide a power storage device that can suppress an internal short circuit due to an assumed foreign object.

本発明の一側面に係る蓄電装置は、第１集電箔の少なくとも一面に設けられた第１活物質層を有する第１電極と、第２集電箔の少なくとも一面に設けられた第２活物質層と、前記第２活物質層上に設けられ前記第１活物質層に対向配置された保護層とを有する第２電極と、前記第１電極と前記第２電極との間に配置されたセパレータと、を備え、前記第１電極及び前記第２電極の一方が正極であり、前記第１電極及び前記第２電極の他方が負極であり、前記保護層の硬さは前記第１活物質層の硬さよりも硬く、前記第１活物質層の厚みと前記第２活物質層の厚みのうちの厚いほうの厚みをＰとし、前記第１活物質層の硬さをｘとし、前記保護層の硬さをｙとし、前記保護層の厚みをＴとし、前記セパレータの厚みをＤとした場合、下記の式（１）及び式（２）を満たす。

Figure 2015216046
A power storage device according to one aspect of the present invention includes a first electrode having a first active material layer provided on at least one surface of a first current collector foil, and a second active material provided on at least one surface of a second current collector foil. A second electrode having a material layer and a protective layer provided on the second active material layer and disposed opposite to the first active material layer; and disposed between the first electrode and the second electrode. A separator, wherein one of the first electrode and the second electrode is a positive electrode, the other of the first electrode and the second electrode is a negative electrode, and the hardness of the protective layer is the first active layer. It is harder than the hardness of the material layer, the thickness of the thickness of the first active material layer and the thickness of the second active material layer is P, the hardness of the first active material layer is x, When the hardness of the protective layer is y, the thickness of the protective layer is T, and the thickness of the separator is D, the following formula ( ) And satisfies the equation (2).
Figure 2015216046

本明細書において、「硬さ」は、例えば、ビッカース硬さ試験で測定されたビッカース硬さ［ＨＶ］である。   In the present specification, the “hardness” is, for example, a Vickers hardness [HV] measured by a Vickers hardness test.

セパレータと第１電極又は第２電極との間には、異物が入る可能性がある。そのような異物としては、電極製造工程の打抜き等のときに第１活物質層又は第２活物質層から落ちる活物質（粒子）又は活物質層の一部（バリ）等が考えられる。よって、保護層の厚み方向における異物の最大サイズは、第１活物質層の厚みと第２活物質層の厚みのうちの厚いほうの厚みＰと同じであると想定される。最大サイズＰの異物がセパレータと第１電極又は第２電極との間に入った場合、上記の式（２）のように、最大サイズＰはセパレータの厚みＤよりも大きいので、異物はセパレータを貫通する。異物がセパレータからはみ出す距離は（Ｐ−Ｄ）となる。はみ出た異物は、ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）だけ第１活物質層内に入り込み、ｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）だけ保護層内に入り込む。したがって、保護層の凹み量はｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）となる。保護層の厚みＴはｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）よりも大きい（上記の式（１）を満たす）ので、保護層の破断が抑制される。その結果、異物による内部短絡が抑制される。よって、上記の式（１）及び（２）を満たす蓄電装置では、セパレータと第１電極又は第２電極との間に異物が入っても、異物による内部短絡を抑制できる。したがって、この蓄電装置では、想定される異物による内部短絡を抑制できる。   There is a possibility that foreign matter enters between the separator and the first electrode or the second electrode. As such a foreign material, an active material (particles) falling from the first active material layer or the second active material layer or a part of the active material layer (burr) at the time of punching the electrode manufacturing process or the like can be considered. Therefore, the maximum size of the foreign matter in the thickness direction of the protective layer is assumed to be the same as the thicker thickness P of the thicknesses of the first active material layer and the second active material layer. When the foreign material of the maximum size P enters between the separator and the first electrode or the second electrode, the maximum size P is larger than the thickness D of the separator as in the above formula (2). To penetrate. The distance that the foreign matter protrudes from the separator is (PD). The protruding foreign matter enters the first active material layer by y / (x + y) × (P−D), and enters the protective layer by x / (x + y) × (P−D). Therefore, the amount of depression of the protective layer is x / (x + y) × (P−D). Since the thickness T of the protective layer is larger than x / (x + y) × (P−D) (the above formula (1) is satisfied), the breakage of the protective layer is suppressed. As a result, an internal short circuit due to foreign matter is suppressed. Therefore, in the power storage device that satisfies the above expressions (1) and (2), even if a foreign substance enters between the separator and the first electrode or the second electrode, an internal short circuit due to the foreign substance can be suppressed. Therefore, in this power storage device, it is possible to suppress an internal short circuit due to an assumed foreign object.

一実施形態において、前記第１活物質層の硬さは前記第２活物質層の硬さよりも硬くてもよい。   In one embodiment, the hardness of the first active material layer may be higher than the hardness of the second active material layer.

この場合、第１活物質層の凹み量ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）が小さくなるので、保護層の凹み量ｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）が大きくなる。そのような場合であっても、保護層の厚みＴはｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）よりも大きい（上記の式（１）を満たす）ので、保護層の破断が抑制される。   In this case, since the dent amount y / (x + y) × (P−D) of the first active material layer is reduced, the dent amount x / (x + y) × (P−D) of the protective layer is increased. Even in such a case, since the thickness T of the protective layer is larger than x / (x + y) × (P−D) (satisfies the above formula (1)), the breakage of the protective layer is suppressed.

一実施形態において、前記第１活物質層の厚みをｔとした場合、下記の式（３）を満たしてもよい。

Figure 2015216046
In one embodiment, when the thickness of the first active material layer is t, the following formula (3) may be satisfied.
Figure 2015216046

セパレータからはみ出た異物は、ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）だけ第１活物質層内に入り込む。したがって、第１活物質層の凹み量はｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）となる。第１活物質層の厚みｔがｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）よりも大きいと（上記の式（３）を満たすと）、異物が第１集電箔に到達しないので、第１活物質層の破断が抑制される。   Foreign matter that protrudes from the separator enters the first active material layer by y / (x + y) × (P−D). Therefore, the dent amount of the first active material layer is y / (x + y) × (P−D). When the thickness t of the first active material layer is larger than y / (x + y) × (P−D) (when the above expression (3) is satisfied), the foreign matter does not reach the first current collector foil. Breaking of the active material layer is suppressed.

一実施形態において、前記第１活物質層の厚みと前記第２活物質層の厚みのうちの厚いほうの厚みは、負極活物質層の厚みであってもよい。   In one embodiment, the thickness of the thickness of the first active material layer and the thickness of the second active material layer may be the thickness of the negative electrode active material layer.

この場合、想定される異物の最大サイズＰは負極活物質層の厚みと同じになる。通常、正極活物質層に含まれるバインダと負極活物質層に含まれるバインダとの違いによって、正極活物質層の活物質等に比べて負極活物質層の活物質等は落ち易い。よって、最大の異物は、主として負極活物質層の活物質等であると想定される。   In this case, the assumed maximum size P of the foreign material is the same as the thickness of the negative electrode active material layer. Usually, the active material and the like of the negative electrode active material layer are more likely to fall than the active material and the like of the positive electrode active material layer due to the difference between the binder contained in the positive electrode active material layer and the binder contained in the negative electrode active material layer. Therefore, the largest foreign substance is assumed to be mainly the active material of the negative electrode active material layer.

一実施形態において、前記第１活物質層は正極活物質層であってもよい。   In one embodiment, the first active material layer may be a positive electrode active material layer.

本発明の一側面によれば、想定される異物による内部短絡を抑制できる蓄電装置が提供され得る。   According to one aspect of the present invention, it is possible to provide a power storage device that can suppress an internal short circuit due to an assumed foreign object.

本実施形態に係る蓄電装置を模式的に示す断面図である。It is sectional drawing which shows typically the electrical storage apparatus which concerns on this embodiment. 第１電極と第２電極との間に異物が入った場合の蓄電装置の一部を模式的に示す断面図である。It is sectional drawing which shows typically a part of electrical storage apparatus when a foreign material enters between the 1st electrode and the 2nd electrode.

以下、添付図面を参照しながら本発明の実施形態が詳細に説明される。図面の説明において、同一又は同等の要素には同一符号が用いられ、重複する説明は省略される。   Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and redundant descriptions are omitted.

図１は、本実施形態に係る蓄電装置を模式的に示す断面図である。図１に示される蓄電装置１は、例えば二次電池又は電気二重層キャパシタ等である。二次電池としては、例えば、リチウムイオン二次電池等の非水電解質二次電池が挙げられる。   FIG. 1 is a cross-sectional view schematically showing the power storage device according to this embodiment. The power storage device 1 shown in FIG. 1 is, for example, a secondary battery or an electric double layer capacitor. Examples of the secondary battery include non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries.

蓄電装置１は、電極組立体２と、電極組立体２を収容するケース４とを備える。ケース４内には電解液３が収容される。電極組立体２は、第１電極としての正極１０と、第２電極としての負極２０と、正極１０と負極２０との間に配置されたセパレータ３０とを備える。複数の正極１０及び複数の負極２０が、セパレータ３０を介して交互に積層されている。電解液３は、例えば有機溶媒系又は非水系の電解液等である。ケース４は導電性を有し、例えばアルミニウム又はアルミニウム合金等の金属からなる。ケース４の形状は例えば直方体状である。   The power storage device 1 includes an electrode assembly 2 and a case 4 that houses the electrode assembly 2. The electrolyte solution 3 is accommodated in the case 4. The electrode assembly 2 includes a positive electrode 10 as a first electrode, a negative electrode 20 as a second electrode, and a separator 30 disposed between the positive electrode 10 and the negative electrode 20. A plurality of positive electrodes 10 and a plurality of negative electrodes 20 are alternately stacked via separators 30. The electrolytic solution 3 is, for example, an organic solvent-based or non-aqueous electrolytic solution. The case 4 has conductivity and is made of a metal such as aluminum or an aluminum alloy. The case 4 has a rectangular parallelepiped shape, for example.

正極１０は、第１集電箔としての金属箔１１と、金属箔１１の少なくとも一面に設けられた第１活物質層としての正極活物質層１２とを有する。本実施形態では、金属箔１１の両面にそれぞれ正極活物質層１２が設けられている。正極１０は、金属箔１１の端部において、正極活物質層１２が設けられていないタブ部を有してもよい。タブ部は、正極１０の上縁部に延び、導電部材を介して正極端子に接続される。   The positive electrode 10 includes a metal foil 11 as a first current collector foil and a positive electrode active material layer 12 as a first active material layer provided on at least one surface of the metal foil 11. In the present embodiment, the positive electrode active material layers 12 are provided on both surfaces of the metal foil 11, respectively. The positive electrode 10 may have a tab portion where the positive electrode active material layer 12 is not provided at the end of the metal foil 11. The tab portion extends to the upper edge portion of the positive electrode 10 and is connected to the positive electrode terminal via the conductive member.

金属箔１１は、例えば、アルミニウム箔、アルミニウム合金箔である。正極活物質層１２は、正極活物質及びバインダを含む。正極活物質層１２は、導電助剤を含んでもよい。正極活物質は、例えば、複合酸化物、金属リチウム、硫黄である。複合酸化物は、マンガン、ニッケル、コバルト及びアルミニウムの少なくとも１つとリチウムとを含む。バインダは、例えば、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、フッ素ゴム等の含フッ素樹脂、ポリプロピレン、ポリエチレン等の熱可塑性樹脂、ポリイミド、ポリアミドイミド等のイミド系樹脂、アルコキシシリノレ基含有樹脂等である。導電助剤は、例えば、カーボンブラック、黒鉛、アセチレンブラック、ケッチェンブラック（登録商標）である。   The metal foil 11 is, for example, an aluminum foil or an aluminum alloy foil. The positive electrode active material layer 12 includes a positive electrode active material and a binder. The positive electrode active material layer 12 may include a conductive additive. The positive electrode active material is, for example, a composite oxide, metallic lithium, or sulfur. The composite oxide includes at least one of manganese, nickel, cobalt, and aluminum and lithium. The binder is, for example, a fluorine-containing resin such as polyvinylidene fluoride, polytetrafluoroethylene or fluororubber, a thermoplastic resin such as polypropylene or polyethylene, an imide resin such as polyimide or polyamideimide, or an alkoxysilanol group-containing resin. . Examples of the conductive auxiliary agent include carbon black, graphite, acetylene black, and ketjen black (registered trademark).

負極２０は、第２集電箔としての金属箔２１と、金属箔２１の少なくとも一面に設けられた第２活物質層としての負極活物質層２２と、負極活物質層２２上に設けられ正極活物質層１２に対向配置された保護層２３とを有する。保護層２３は、負極活物質層２２の表面全体を覆ってもよい。本実施形態では、金属箔２１の両面にそれぞれ負極活物質層２２が設けられている。負極２０は、金属箔２１の端部において、負極活物質層２２が設けられていないタブ部を有してもよい。タブ部は、負極２０の上縁部に延び、導電部材を介して負極端子に接続される。   The negative electrode 20 includes a metal foil 21 as a second current collector foil, a negative electrode active material layer 22 as a second active material layer provided on at least one surface of the metal foil 21, and a positive electrode provided on the negative electrode active material layer 22. And a protective layer 23 disposed opposite to the active material layer 12. The protective layer 23 may cover the entire surface of the negative electrode active material layer 22. In the present embodiment, the negative electrode active material layers 22 are respectively provided on both surfaces of the metal foil 21. The negative electrode 20 may have a tab portion where the negative electrode active material layer 22 is not provided at the end of the metal foil 21. The tab portion extends to the upper edge portion of the negative electrode 20 and is connected to the negative electrode terminal via a conductive member.

金属箔２１は、例えば、銅箔、銅合金箔である。負極活物質層２２は、負極活物質及びバインダを含む。負極活物質層２２は、導電助剤を含んでもよい。負極活物質は、例えば、黒鉛、高配向性グラファイト、メソカーボンマイクロビーズ、ハードカーボン、ソフトカーボン等のカーボン、リチウム、ナトリウム等のアルカリ金属、金属化合物、ＳｉＯｘ（０．５≦ｘ≦１．５）等の金属酸化物、ホウ素添加炭素である。バインダ及び導電助剤としては、例えば、正極１０に用いられるバインダ及び導電助剤と同じものが挙げられる。バインダとしては、さらに、例えばカルボキシメチルセルロース、メチルセルロース、スチレンブタジエンゴム、アルコキシシリル基含有樹脂等が挙げられる。保護層２３は、例えば多孔質絶縁層である。保護層２３は、例えばセラミック等の絶縁材料と、バインダとを含む。セラミックは、例えばＡｌ２Ｏ３、ＳｉＯ２、ＴｉＯ２等である。バインダとしては、例えば、正極１０に用いられるバインダと同じものが挙げられる。 The metal foil 21 is, for example, a copper foil or a copper alloy foil. The negative electrode active material layer 22 includes a negative electrode active material and a binder. The negative electrode active material layer 22 may include a conductive additive. Examples of the negative electrode active material include graphite, highly oriented graphite, carbon such as mesocarbon microbeads, hard carbon, and soft carbon, alkali metals such as lithium and sodium, metal compounds, and SiOx (0.5 ≦ x ≦ 1.5). ) And the like, and boron-added carbon. As a binder and a conductive support agent, the same thing as the binder and conductive support agent used for the positive electrode 10 are mentioned, for example. Examples of the binder further include carboxymethyl cellulose, methyl cellulose, styrene butadiene rubber, and alkoxysilyl group-containing resin. The protective layer 23 is, for example, a porous insulating layer. The protective layer 23 includes, for example, an insulating material such as ceramic and a binder. The ceramic is, for example, Al 2 O 3 , SiO 2 , TiO 2 or the like. As a binder, the same thing as the binder used for the positive electrode 10 is mentioned, for example.

セパレータ３０は、正極１０と負極２０とを隔離し、両極の接触による短絡を防止しつつ、リチウムイオンを通過させる。セパレータ３０の一方の面が保護層２３に密着し、セパレータ３０の他方の面が正極活物質層１２に密着してもよい。セパレータ３０は、例えば、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等のポリオレフィン系樹脂からなる多孔質フィルム、ポリプロピレン、ポリエチレンテレフタレート（ＰＥＴ）、メチルセルロース等からなる織布又は不織布である。   The separator 30 separates the positive electrode 10 and the negative electrode 20 and allows lithium ions to pass through while preventing a short circuit due to contact between the two electrodes. One surface of the separator 30 may be in close contact with the protective layer 23, and the other surface of the separator 30 may be in close contact with the positive electrode active material layer 12. The separator 30 is, for example, a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), a woven fabric or a non-woven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose, or the like.

図２は、第１電極と第２電極との間に異物が入った場合の蓄電装置の一部を模式的に示す断面図である。図２では、蓄電装置１の正極１０と負極２０との間に異物Ａが入っている。   FIG. 2 is a cross-sectional view schematically showing a part of the power storage device when a foreign substance enters between the first electrode and the second electrode. In FIG. 2, foreign matter A is present between the positive electrode 10 and the negative electrode 20 of the power storage device 1.

本実施形態では、正極活物質層１２の硬さが負極活物質層２２の硬さよりも硬い。保護層２３の硬さは正極活物質層１２の硬さよりも硬い。負極活物質層２２の硬さは、セパレータ３０の硬さよりも硬い。   In the present embodiment, the positive electrode active material layer 12 is harder than the negative electrode active material layer 22. The hardness of the protective layer 23 is harder than the hardness of the positive electrode active material layer 12. The hardness of the negative electrode active material layer 22 is harder than the hardness of the separator 30.

正極活物質層１２の硬さ及び負極活物質層２２の硬さは、活物質層の密度によって決まり、密度が高いほど硬い。したがって、活物質層の密度を所望の密度（予め設定された値）にすることによって、活物質層の硬さを調整することができる。密度は、例えば、活物質層を形成するための電極ペーストの固形分率、金属箔１１，２１に電極ペーストを塗布して乾燥させた後のプレス工程におけるプレス圧等を調整することによって調整され得る。   The hardness of the positive electrode active material layer 12 and the hardness of the negative electrode active material layer 22 are determined by the density of the active material layer, and the higher the density, the harder. Therefore, the hardness of the active material layer can be adjusted by setting the density of the active material layer to a desired density (a preset value). The density is adjusted, for example, by adjusting the solid content ratio of the electrode paste for forming the active material layer, the pressing pressure in the pressing step after the electrode paste is applied to the metal foils 11 and 21, and dried. obtain.

保護層２３の硬さは、保護層２３に用いる素材の選択、保護層２３の密度によって決まり、密度が高いほど硬い。したがって、保護層２３の密度を所望の密度（予め設定された値）にすることによって、保護層２３の硬さを調整することができる。密度は、例えば、保護層２３を形成するためのペーストの固形分率、ペーストを塗布して乾燥させた後のプレス工程におけるプレス圧等を調整することによって調整され得る。   The hardness of the protective layer 23 is determined by the selection of the material used for the protective layer 23 and the density of the protective layer 23, and the higher the density, the harder. Therefore, the hardness of the protective layer 23 can be adjusted by setting the density of the protective layer 23 to a desired density (a preset value). The density can be adjusted, for example, by adjusting the solid content ratio of the paste for forming the protective layer 23, the pressing pressure in the pressing step after the paste is applied and dried, and the like.

セパレータ３０の硬さは、セパレータ３０に用いる素材の選択、気孔率又は気孔径の調整等によって調整され得る。   The hardness of the separator 30 can be adjusted by selecting a material used for the separator 30, adjusting the porosity or the pore diameter, and the like.

本実施形態では、負極活物質層２２が正極活物質層１２よりも厚い。正極活物質層１２及び負極活物質層２２はセパレータ３０よりも厚い。保護層２３は正極活物質層１２、負極活物質層２２及びセパレータ３０よりも薄い。保護層２３は、蓄電装置１の容量に寄与しないので、蓄電装置１の小型化のためには薄い方が好ましい。負極活物質層２２の厚み、正極活物質層１２の厚み及び保護層２３の厚みは、例えば、ペーストの塗布量、プレス工程におけるプレスロール間隔の調整等によって調整され得る。セパレータ３０の厚みは、例えば素材を引っ張って薄くする際の力等によって調整され得る。   In the present embodiment, the negative electrode active material layer 22 is thicker than the positive electrode active material layer 12. The positive electrode active material layer 12 and the negative electrode active material layer 22 are thicker than the separator 30. The protective layer 23 is thinner than the positive electrode active material layer 12, the negative electrode active material layer 22, and the separator 30. Since the protective layer 23 does not contribute to the capacity of the power storage device 1, the protective layer 23 is preferably thinner in order to reduce the size of the power storage device 1. The thickness of the negative electrode active material layer 22, the thickness of the positive electrode active material layer 12, and the thickness of the protective layer 23 can be adjusted, for example, by adjusting the amount of paste applied, the press roll interval in the pressing step, and the like. The thickness of the separator 30 can be adjusted by, for example, a force when the material is pulled and thinned.

正極活物質層１２の厚みと負極活物質層２２の厚みのうち厚いほうである負極活物質層２２の厚みをＰとし、正極活物質層１２の硬さをｘとし、保護層２３の硬さをｙとし、保護層２３の厚みをＴとし、セパレータ３０の厚みをＤとした場合、下記の式（１）及び式（２）を満たす。
ｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）＜Ｔ…（１）
Ｐ＞Ｄ…（２） The thickness of the positive electrode active material layer 12 and the thickness of the negative electrode active material layer 22, which is the thicker one, is P, the positive electrode active material layer 12 is x, and the protective layer 23 is hard. Is y, the thickness of the protective layer 23 is T, and the thickness of the separator 30 is D, the following expressions (1) and (2) are satisfied.
x / (x + y) × (P−D) <T (1)
P> D (2)

正極活物質層１２の厚みをｔとした場合、下記の式（３）を満たしてもよい。
ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）＜ｔ…（３） When the thickness of the positive electrode active material layer 12 is t, the following formula (3) may be satisfied.
y / (x + y) × (P−D) <t (3)

セパレータ３０と正極１０又は負極２０との間には、異物Ａが入る可能性がある。そのような異物Ａとしては、電極製造工程の打抜き等のときに正極活物質層１２又は負極活物質層２２から落ちる活物質（粒子）又は活物質層の一部（バリ）等が考えられる。よって、保護層２３の厚み方向における異物Ａの最大サイズは、正極活物質層１２の厚みと負極活物質層２２の厚みのうちの厚いほうである負極活物質層２２の厚みＰと同じであると想定される。最大サイズＰの異物Ａがセパレータ３０と正極１０又は負極２０との間に入った場合、上記の式（２）のように、最大サイズＰはセパレータ３０の厚みＤよりも大きいので、異物Ａはセパレータ３０を貫通する。異物Ａがセパレータ３０からはみ出す距離は（Ｐ−Ｄ）となる。はみ出た異物Ａは、ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）だけ正極活物質層１２内に入り込み、ｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）だけ保護層２３内に入り込む。したがって、保護層２３の凹み量はｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）となる。保護層２３の厚みＴはｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）よりも大きい（上記の式（１）を満たす）ので、保護層２３の破断が抑制される。その結果、異物Ａによる内部短絡が抑制される。よって、上記の式（１）及び（２）を満たす蓄電装置１では、セパレータ３０と正極１０又は負極２０との間に最大サイズＰの異物Ａが入っても、異物Ａによる内部短絡を抑制できる。したがって、蓄電装置１では、想定される異物Ａによる内部短絡を抑制できる。   There is a possibility that foreign matter A enters between the separator 30 and the positive electrode 10 or the negative electrode 20. As such a foreign material A, an active material (particle) falling from the positive electrode active material layer 12 or the negative electrode active material layer 22 or a part of the active material layer (burr) at the time of punching of the electrode manufacturing process or the like can be considered. Therefore, the maximum size of the foreign matter A in the thickness direction of the protective layer 23 is the same as the thickness P of the negative electrode active material layer 22 which is the larger of the thickness of the positive electrode active material layer 12 and the thickness of the negative electrode active material layer 22. It is assumed. When the foreign matter A having the maximum size P enters between the separator 30 and the positive electrode 10 or the negative electrode 20, the maximum size P is larger than the thickness D of the separator 30 as in the above formula (2). The separator 30 is penetrated. The distance that the foreign matter A protrudes from the separator 30 is (P−D). The protruding foreign matter A enters the positive electrode active material layer 12 by y / (x + y) × (P−D), and enters the protective layer 23 by x / (x + y) × (P−D). Therefore, the amount of depression of the protective layer 23 is x / (x + y) × (P−D). Since the thickness T of the protective layer 23 is larger than x / (x + y) × (P−D) (the above formula (1) is satisfied), the breakage of the protective layer 23 is suppressed. As a result, an internal short circuit due to the foreign matter A is suppressed. Therefore, in the power storage device 1 that satisfies the above formulas (1) and (2), even if the foreign matter A having the maximum size P enters between the separator 30 and the positive electrode 10 or the negative electrode 20, an internal short circuit due to the foreign matter A can be suppressed. . Therefore, in the power storage device 1, an internal short circuit due to the assumed foreign object A can be suppressed.

セパレータ３０からはみ出た異物Ａは、ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）だけ正極活物質層１２内に入り込む。したがって、正極活物質層１２の凹み量はｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）となる。正極活物質層１２の厚みｔがｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）よりも大きいと（上記の式（３）を満たすと）、異物Ａが金属箔１１に到達しないので、正極活物質層１２の破断が抑制される。   The foreign matter A protruding from the separator 30 enters the positive electrode active material layer 12 by y / (x + y) × (P−D). Therefore, the amount of depression of the positive electrode active material layer 12 is y / (x + y) × (P−D). When the thickness t of the positive electrode active material layer 12 is larger than y / (x + y) × (P−D) (when the above formula (3) is satisfied), the foreign matter A does not reach the metal foil 11, so the positive electrode active material Breakage of the layer 12 is suppressed.

本実施形態では、正極活物質層１２の硬さが負極活物質層２２の硬さよりも硬い。よって、正極活物質層１２の凹み量ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）が小さくなるので、保護層２３の凹み量ｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）が大きくなる。そのような場合であっても、保護層２３の厚みＴがｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）よりも大きい（上記の式（１）を満たす）ので、保護層２３の破断が抑制される。   In the present embodiment, the positive electrode active material layer 12 is harder than the negative electrode active material layer 22. Therefore, since the dent amount y / (x + y) × (P−D) of the positive electrode active material layer 12 decreases, the dent amount x / (x + y) × (P−D) of the protective layer 23 increases. Even in such a case, since the thickness T of the protective layer 23 is larger than x / (x + y) × (P−D) (the above formula (1) is satisfied), the breakage of the protective layer 23 is suppressed. The

本実施形態では、保護層２３の厚み方向における異物Ａの最大サイズＰは負極活物質層２２の厚みＰと同じである。通常、正極活物質層１２に含まれるバインダと負極活物質層２２に含まれるバインダとの違いによって、正極活物質層１２の活物質等に比べて負極活物質層２２の活物質等は落ち易い。よって、最大の異物Ａは、主として負極活物質層２２の活物質等であると想定される。   In the present embodiment, the maximum size P of the foreign matter A in the thickness direction of the protective layer 23 is the same as the thickness P of the negative electrode active material layer 22. Usually, the active material of the negative electrode active material layer 22 is more likely to fall than the active material of the positive electrode active material layer 12 due to the difference between the binder contained in the positive electrode active material layer 12 and the binder contained in the negative electrode active material layer 22. . Therefore, it is assumed that the largest foreign material A is mainly the active material of the negative electrode active material layer 22.

蓄電装置１を製造する際に、負極活物質層２２の厚みをＰとし、正極活物質層１２の硬さをｘとし、保護層２３の硬さをｙとし、保護層２３の厚みをＴとし、セパレータ３０の厚みをＤとした場合、上記の式（１）及び式（２）を満たすように、負極活物質層２２の厚み、正極活物質層１２の硬さ、保護層２３の硬さ、保護層２３の厚み、及びセパレータ３０の厚みを決定してもよい。また、正極活物質層１２の厚みをｔとした場合、上記の式（３）を満たすように、正極活物質層１２の厚みを決定してもよい。   When the power storage device 1 is manufactured, the thickness of the negative electrode active material layer 22 is P, the hardness of the positive electrode active material layer 12 is x, the hardness of the protective layer 23 is y, and the thickness of the protective layer 23 is T. When the thickness of the separator 30 is D, the thickness of the negative electrode active material layer 22, the hardness of the positive electrode active material layer 12, and the hardness of the protective layer 23 so as to satisfy the above formulas (1) and (2). The thickness of the protective layer 23 and the thickness of the separator 30 may be determined. In addition, when the thickness of the positive electrode active material layer 12 is t, the thickness of the positive electrode active material layer 12 may be determined so as to satisfy the above formula (3).

各層の厚み及び硬さは例えば以下のように決定される。まず、電極組立体２のサイズ、正極１０及び負極２０の積層数等を考慮して、正極活物質層１２の厚みｔ、負極活物質層２２の厚みＰ、保護層２３の厚みＴ、セパレータ３０の厚みＤを決定する。次に、上記の式（１）〜式（３）を満たすように、正極活物質層１２の硬さｘ及び保護層２３の硬さｙを決定する。次に、決められた厚み及び硬さに従って、電極組立体２を作製する。   The thickness and hardness of each layer are determined as follows, for example. First, in consideration of the size of the electrode assembly 2, the number of stacked positive electrodes 10 and negative electrodes 20, the thickness t of the positive electrode active material layer 12, the thickness P of the negative electrode active material layer 22, the thickness T of the protective layer 23, the separator 30. Thickness D is determined. Next, the hardness x of the positive electrode active material layer 12 and the hardness y of the protective layer 23 are determined so as to satisfy the above formulas (1) to (3). Next, the electrode assembly 2 is produced according to the determined thickness and hardness.

以上、本発明の好適な実施形態について詳細に説明されたが、本発明は上記実施形態に限定されない。   As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment.

例えば、正極活物質層１２の硬さが負極活物質層２２の硬さと同じであってもよい。また、負極活物質層２２が正極活物質層１２よりも硬くてもよい。この場合、正極活物質層１２の硬さｘが小さくなる。すなわち、正極活物質層１２が軟らかくなる。よって、正極活物質層１２の凹み量ｙ／（ｘ＋ｙ）×（Ｐ−Ｄ）が大きくなり、保護層２３の凹み量ｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）が小さくなる。   For example, the hardness of the positive electrode active material layer 12 may be the same as the hardness of the negative electrode active material layer 22. Further, the negative electrode active material layer 22 may be harder than the positive electrode active material layer 12. In this case, the hardness x of the positive electrode active material layer 12 is reduced. That is, the positive electrode active material layer 12 becomes soft. Therefore, the dent amount y / (x + y) × (PD) of the positive electrode active material layer 12 is increased, and the dent amount x / (x + y) × (PD) of the protective layer 23 is decreased.

また、正極活物質層１２の厚みが負極活物質層２２の厚みと同じであってもよい。さらに、正極活物質層１２が負極活物質層２２よりも厚くてもよい。この場合、上記の式（１）〜式（３）において、負極活物質層２２の厚みではなく、正極活物質層１２の厚みをＰとする。正極活物質層１２の厚みが異物Ａの最大サイズＰと同じになる。   Further, the thickness of the positive electrode active material layer 12 may be the same as the thickness of the negative electrode active material layer 22. Further, the positive electrode active material layer 12 may be thicker than the negative electrode active material layer 22. In this case, in the above formulas (1) to (3), P is not the thickness of the negative electrode active material layer 22 but the thickness of the positive electrode active material layer 12. The thickness of the positive electrode active material layer 12 is the same as the maximum size P of the foreign matter A.

また、負極２０が保護層２３を有しておらず、正極１０が保護層２３を有してもよい。この場合、負極２０が第１電極に相当し、正極１０が第２電極に相当する。負極活物質層２２が第１活物質層に相当し、正極活物質層１２が第２活物質層に相当する。負極活物質層２２の硬さが第１活物質層の硬さに相当する。よって、上記の式（１）及び式（３）において、正極活物質層１２の硬さではなく、負極活物質層２２の硬さがｘとなり、正極活物質層１２の厚さではなく、負極活物質層２２の厚さがｔとなる。この場合であっても、保護層２３の厚みＴがｘ／（ｘ＋ｙ）×（Ｐ−Ｄ）よりも大きい（上記の式（１）を満たす）ので、保護層２３の破断が抑制される。   The negative electrode 20 may not have the protective layer 23, and the positive electrode 10 may have the protective layer 23. In this case, the negative electrode 20 corresponds to the first electrode, and the positive electrode 10 corresponds to the second electrode. The negative electrode active material layer 22 corresponds to a first active material layer, and the positive electrode active material layer 12 corresponds to a second active material layer. The hardness of the negative electrode active material layer 22 corresponds to the hardness of the first active material layer. Therefore, in the above formulas (1) and (3), not the hardness of the positive electrode active material layer 12 but the hardness of the negative electrode active material layer 22 is x, not the thickness of the positive electrode active material layer 12 but the negative electrode The thickness of the active material layer 22 is t. Even in this case, since the thickness T of the protective layer 23 is larger than x / (x + y) × (P−D) (the above formula (1) is satisfied), the breakage of the protective layer 23 is suppressed.

１…蓄電装置、２…電極組立体、３…電解液、４…ケース、１０…正極（第１電極）、１１…金属箔（第１集電箔）、１２…正極活物質層（第１活物質層）、２０…負極（第２電極）、２１…金属箔（第２集電箔）、２２…負極活物質層（第２活物質層）、２３…保護層、３０…セパレータ。   DESCRIPTION OF SYMBOLS 1 ... Power storage device, 2 ... Electrode assembly, 3 ... Electrolyte solution, 4 ... Case, 10 ... Positive electrode (1st electrode), 11 ... Metal foil (1st current collection foil), 12 ... Positive electrode active material layer (1st Active material layer), 20 ... Negative electrode (second electrode), 21 ... Metal foil (second current collector foil), 22 ... Negative electrode active material layer (second active material layer), 23 ... Protective layer, 30 ... Separator.

Claims (5)

第１集電箔の少なくとも一面に設けられた第１活物質層を有する第１電極と、
第２集電箔の少なくとも一面に設けられた第２活物質層と、前記第２活物質層上に設けられ前記第１活物質層に対向配置された保護層とを有する第２電極と、
前記第１電極と前記第２電極との間に配置されたセパレータと、
を備え、
前記第１電極及び前記第２電極の一方が正極であり、
前記第１電極及び前記第２電極の他方が負極であり、
前記保護層の硬さは前記第１活物質層の硬さよりも硬く、
前記第１活物質層の厚みと前記第２活物質層の厚みのうちの厚いほうの厚みをＰとし、前記第１活物質層の硬さをｘとし、前記保護層の硬さをｙとし、前記保護層の厚みをＴとし、前記セパレータの厚みをＤとした場合、下記の式（１）及び式（２）を満たす、蓄電装置。
Figure 2015216046
 A first electrode having a first active material layer provided on at least one surface of the first current collector foil;
A second electrode having a second active material layer provided on at least one surface of the second current collector foil, and a protective layer provided on the second active material layer and disposed opposite to the first active material layer;
A separator disposed between the first electrode and the second electrode;
With
One of the first electrode and the second electrode is a positive electrode;
The other of the first electrode and the second electrode is a negative electrode,
The hardness of the protective layer is harder than the hardness of the first active material layer,
The thickness of the thickness of the first active material layer and the thickness of the second active material layer is P, the hardness of the first active material layer is x, and the hardness of the protective layer is y. A power storage device satisfying the following formulas (1) and (2), where T is the thickness of the protective layer and D is the thickness of the separator.
Figure 2015216046
 前記第１活物質層の硬さは前記第２活物質層の硬さよりも硬い、請求項１に記載の蓄電装置。   The power storage device according to claim 1, wherein the hardness of the first active material layer is harder than the hardness of the second active material layer. 前記第１活物質層の厚みをｔとした場合、下記の式（３）を満たす、請求項１又は２に記載の蓄電装置。
Figure 2015216046
 The power storage device according to claim 1 or 2, wherein when the thickness of the first active material layer is t, the following formula (3) is satisfied.
Figure 2015216046
 前記第１活物質層の厚みと前記第２活物質層の厚みのうちの厚いほうの厚みは、負極活物質層の厚みである、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 a thickness of the thickness of the first active material layer and the thickness of the second active material layer is a thickness of the negative electrode active material layer. . 前記第１活物質層は正極活物質層である、請求項１〜４のいずれか一項に記載の蓄電装置。   The power storage device according to claim 1, wherein the first active material layer is a positive electrode active material layer.
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009054455A (en) * 2007-08-28 2009-03-12 Sony Corp Nonaqueous electrolyte secondary battery and manufacturing method of electrode

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009054455A (en) * 2007-08-28 2009-03-12 Sony Corp Nonaqueous electrolyte secondary battery and manufacturing method of electrode

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