JP2022024868A - Non-aqueous secondary battery - Google Patents

Non-aqueous secondary battery Download PDF

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JP2022024868A
JP2022024868A JP2020127692A JP2020127692A JP2022024868A JP 2022024868 A JP2022024868 A JP 2022024868A JP 2020127692 A JP2020127692 A JP 2020127692A JP 2020127692 A JP2020127692 A JP 2020127692A JP 2022024868 A JP2022024868 A JP 2022024868A
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insulating layer
mass
secondary battery
less
aqueous secondary
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JP7402766B2 (en
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亘 森村
Wataru Morimura
聡 西川
Satoshi Nishikawa
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Teijin Ltd
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Priority to US18/006,669 priority patent/US20230282936A1/en
Priority to PCT/JP2021/027797 priority patent/WO2022025081A1/en
Priority to KR1020237002170A priority patent/KR20230028435A/en
Priority to EP21849844.2A priority patent/EP4190860A4/en
Priority to CN202180060101.6A priority patent/CN116134089A/en
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Abstract

To provide a non-aqueous secondary battery having high reliability.SOLUTION: A non-aqueous secondary battery includes a positive electrode, a negative electrode, an insulating layer which is a single layer whose one surface comes in contact with the positive electrode and the other surface comes in contact with the negative electrode, and contains a polyvinylidene fluoride-based resin and inorganic particles, and an electrolyte. A weight average molecular weight of the polyvinylidene fluoride-based resin contained in the insulating layer is 900,000 or more and 1,500,000 or less, and a mass ratio of the inorganic particles in the insulating layer is 50 mass% or more and less than 90 mass%.SELECTED DRAWING: Figure 1

Description

本開示は、非水系二次電池に関する。 The present disclosure relates to non-aqueous secondary batteries.

非水系二次電池において、正極と負極とを絶縁させる目的で絶縁層又はセパレータが使用されている。
例えば特許文献1又は特許文献2には、正極活物質又は負極活物質を含む活物質層と、この活物質層の上に積層された耐熱性高分子及び無機フィラーを含む耐熱性多孔質層とを備えた非水電解質電池用電極シートが開示されている。
例えば特許文献3には、正極と、負極と、フッ素系樹脂及び絶縁性無機粒子を含有するセラミックセパレータ層と、リチウムイオン伝導性非水電解質とを含む電池要素と、電池要素を収容する外装体と、を備えたリチウムイオン二次電池が開示されている。
例えば特許文献4には、互いに平均粒径の異なる2種以上の樹脂粒子を含有するセパレータ層形成用組成物を電極上に塗工する工程と、電極上に塗工されたセパレータ層形成用組成物を塗工端部から乾燥させて電極上に該電極と一体化したセパレータ層を形成する工程と、セパレータ層が形成された電極と、対極と、電解液とを用いて二次電池を構築する工程と、を有する二次電池の製造方法が開示されている。
例えば特許文献5には、平均粒径0.5μm~3.0μmの水酸化マグネシウムを含む多孔質層であるセパレータと、電極とを接合一体化してなるリチウムイオン二次電池用セパレータ電極一体型蓄電素子が開示されている。
例えば特許文献6には、正極と、負極と、正極と負極との間に配置され正極と負極のうち少なくとも一方を接着する接着性樹脂層とを備えた電池であって、接着性樹脂層が平均径0.01μm~1μmのフィラーと樹脂とを含む電池が開示されている。
例えば特許文献7には、固体粒状材料及びポリマー結合剤を含有するセパレータ前駆体溶液を電極上にスクリーン印刷により配置する工程と、セパレータ前駆体溶液を薄膜の形態の多孔性セパレータに変化させる工程と、を有する多孔性セパレータの製造方法が開示されている。
例えば特許文献8には、多孔質基材と、ポリフッ化ビニリデン系樹脂を含み結晶サイズが1nm~13nmである接着性多孔質層と、を備えたセパレータを用いた非水系二次電池が開示されている。
例えば特許文献9には、多孔質基材と、重量平均分子量60万~300万のポリフッ化ビニリデン系樹脂を含み空孔率が30%~60%である接着性多孔質層と、を備えたセパレータを用いた非水系二次電池が開示されている。
例えば特許文献10には、無機粒子及び有機バインダを含む複合材料からなり、顔料体積濃度と臨界顔料体積濃度との比が0.7~1.15であるセパレータを用いた蓄電デバイスが開示されている。
例えば特許文献11には、集電体と、集電体の一面に形成された電極活物質層と、電極活物質層上に形成され、無機粒子及びバインダ高分子を含む有無機多孔性層と、有無機多孔性層上に形成された多孔性の第1支持層と、を含むシート型の二次電池用電極が開示されている。
例えば特許文献12には、多孔質基材と、バインダ樹脂及び平均一次粒径が0.01μm以上0 .30μm未満である硫酸バリウム粒子を含み硫酸バリウム粒子の体積割合が50体積%~90体積%である耐熱性多孔質層と、を備えたセパレータを用いた非水系二次電池が開示されている。
例えば特許文献13には、正極活物質層を有する正極と、負極活物質層を有する負極と、セパレータと、電解液と、正極活物質層又は負極活物質層とセパレータとの間に配置されたAl及びポリフッ化ビニリデンを含有する無機粒子層と、を有するリチウムイオン二次電池が開示されている。
例えば特許文献14には、多孔質基材と、単量体成分としてフッ化ビニリデン及びアクリル系モノマーを含み融点が130℃~148℃であるポリフッ化ビニリデン系樹脂を含む接着性多孔質層と、を備えたセパレータを用いた非水系二次電池が開示されている。
In a non-aqueous secondary battery, an insulating layer or a separator is used for the purpose of insulating the positive electrode and the negative electrode.
For example, Patent Document 1 or Patent Document 2 describes an active material layer containing a positive electrode active material or a negative electrode active material, and a heat-resistant porous layer containing a heat-resistant polymer and an inorganic filler laminated on the active material layer. Disclosed is an electrode sheet for a non-aqueous electrolyte battery.
For example, Patent Document 3 describes a positive electrode, a negative electrode, a battery element containing a fluororesin and a ceramic separator layer containing insulating inorganic particles, a battery element containing a lithium ion conductive non-aqueous electrolyte, and an exterior body containing the battery element. A lithium ion secondary battery equipped with the above is disclosed.
For example, Patent Document 4 describes a step of coating a separator layer forming composition containing two or more kinds of resin particles having different average particle sizes on an electrode, and a separator layer forming composition coated on the electrode. A secondary battery is constructed by using a step of drying an object from the coated end to form a separator layer integrated with the electrode on an electrode, an electrode on which the separator layer is formed, a counter electrode, and an electrolytic solution. And a method of manufacturing a secondary battery having the above-mentioned steps are disclosed.
For example, Patent Document 5 describes a separator electrode integrated storage device for a lithium ion secondary battery, which is formed by joining and integrating a separator, which is a porous layer containing magnesium hydroxide having an average particle size of 0.5 μm to 3.0 μm, and an electrode. The element is disclosed.
For example, Patent Document 6 describes a battery including a positive electrode, a negative electrode, and an adhesive resin layer arranged between the positive electrode and the negative electrode and adhering at least one of the positive electrode and the negative electrode, wherein the adhesive resin layer is provided. A battery containing a filler having an average diameter of 0.01 μm to 1 μm and a resin is disclosed.
For example, Patent Document 7 describes a step of arranging a separator precursor solution containing a solid granular material and a polymer binder on an electrode by screen printing, and a step of changing the separator precursor solution into a porous separator in the form of a thin film. A method for producing a porous separator having the above is disclosed.
For example, Patent Document 8 discloses a non-aqueous secondary battery using a separator provided with a porous substrate and an adhesive porous layer containing a polyvinylidene fluoride-based resin and having a crystal size of 1 nm to 13 nm. ing.
For example, Patent Document 9 includes a porous substrate and an adhesive porous layer containing a polyvinylidene fluoride-based resin having a weight average molecular weight of 600,000 to 3,000,000 and having a porosity of 30% to 60%. A non-aqueous secondary battery using a separator is disclosed.
For example, Patent Document 10 discloses a power storage device using a separator made of a composite material containing inorganic particles and an organic binder and having a ratio of a pigment volume concentration to a critical pigment volume concentration of 0.7 to 1.15. There is.
For example, Patent Document 11 describes a current collector, an electrode active material layer formed on one surface of the current collector, and a porous layer formed on the electrode active material layer and containing inorganic particles and a binder polymer. Disclosed is a sheet-type secondary battery electrode including a porous first support layer formed on the presence / absence machine porous layer.
For example, Patent Document 12 describes a porous substrate, a binder resin, and an average primary particle size of 0.01 μm or more. A non-aqueous secondary battery using a separator provided with a heat-resistant porous layer containing barium sulfate particles having a size of less than 30 μm and having a volume ratio of barium sulfate particles of 50% by volume to 90% by volume is disclosed.
For example, in Patent Document 13, a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, a separator, an electrolytic solution, and a positive electrode active material layer or a negative electrode active material layer and a separator are arranged. A lithium ion secondary battery having an inorganic particle layer containing Al 2 O 3 and polyvinylidene fluoride is disclosed.
For example, Patent Document 14 describes a porous substrate, an adhesive porous layer containing vinylidene fluoride and an acrylic monomer as monomer components, and a polyvinylidene fluoride resin having a melting point of 130 ° C. to 148 ° C. A non-aqueous secondary battery using a separator provided with the above is disclosed.

特開2010-056037号公報Japanese Unexamined Patent Publication No. 2010-056037 特開2011-108516号公報Japanese Unexamined Patent Publication No. 2011-108516 特開2015-191710号公報JP-A-2015-191710 特開2016-177962号公報Japanese Unexamined Patent Publication No. 2016-179962 特開2017-123269号公報Japanese Unexamined Patent Publication No. 2017-123269 特許第4077045号公報Japanese Patent No. 4077045 特許第4790880号公報Japanese Patent No. 4790880 特許第4988972号公報Japanese Patent No. 4988972 特許第5129895号公報Japanese Patent No. 5129895 特許第5880555号公報Japanese Patent No. 5880555 特許第5938523号公報Japanese Patent No. 59385523 特許第6526359号公報Japanese Patent No. 6526359 特許第6597267号公報Japanese Patent No. 6597267 国際公開第2018/212252号International Publication No. 2018/212252

非水系二次電池は、放電特性、クーロン効率、セル強度のいずれにも優れ、すなわち信頼性が高いことが望まれる。非水系二次電池を構成する部材の一つである絶縁層には、非水系二次電池の信頼性を高めるために、電気的絶縁性、イオン透過性、電極に対する接着性などが要求される。 It is desired that the non-aqueous secondary battery has excellent discharge characteristics, coulombic efficiency, and cell strength, that is, high reliability. The insulating layer, which is one of the members constituting the non-aqueous secondary battery, is required to have electrical insulation, ion permeability, adhesion to electrodes, etc. in order to improve the reliability of the non-aqueous secondary battery. ..

本開示の実施形態は、上記状況のもとになされた。
本開示の実施形態は、信頼性の高い非水系二次電池を提供することを目的とし、これを達成することを課題とする。
The embodiments of the present disclosure have been made under the above circumstances.
An embodiment of the present disclosure aims to provide a highly reliable non-aqueous secondary battery, and an object of the present invention is to achieve this.

前記課題を解決するための具体的手段には、以下の態様が含まれる。 Specific means for solving the above-mentioned problems include the following aspects.

<1> 正極と、負極と、一方の面が前記正極に接し他方の面が前記負極に接する単一層であり、ポリフッ化ビニリデン系樹脂及び無機粒子を含有する絶縁層と、電解液と、を備え、
前記絶縁層に含まれる前記ポリフッ化ビニリデン系樹脂の重量平均分子量が90万以上150万以下であり、
前記絶縁層に占める前記無機粒子の質量割合が50質量%以上90質量%未満である、
非水系二次電池。
<2> 前記無機粒子が金属水酸化物粒子及び金属硫酸塩粒子からなる群から選ばれる少なくとも1種を含む、<1>に記載の非水系二次電池。
<3> 前記絶縁層に含まれる前記無機粒子の平均一次粒径が0.01μm以上1.00μm未満である、<1>又は<2>に記載の非水系二次電池。
<4> 前記絶縁層の厚さが5μm以上30μm以下である、<1>~<3>のいずれか1つに記載の非水系二次電池。
<5> 前記絶縁層の空孔率が40%以上80%未満である、<1>~<4>のいずれか1つに記載の非水系二次電池。
<6> 前記絶縁層の単位面積当たりの質量が4g/m以上40g/m未満である、<1>~<5>のいずれか1つに記載の非水系二次電池。
<7> リチウムイオンのドープ及び脱ドープにより起電力を得る、<1>~<6>のいずれか1つに記載の非水系二次電池。
<1> A positive electrode, a negative electrode, a single layer having one surface in contact with the positive electrode and the other surface in contact with the negative electrode, an insulating layer containing a polyvinylidene fluoride-based resin and inorganic particles, and an electrolytic solution. Prepare,
The weight average molecular weight of the polyvinylidene fluoride-based resin contained in the insulating layer is 900,000 or more and 1.5 million or less.
The mass ratio of the inorganic particles to the insulating layer is 50% by mass or more and less than 90% by mass.
Non-water-based secondary battery.
<2> The non-aqueous secondary battery according to <1>, wherein the inorganic particles contain at least one selected from the group consisting of metal hydroxide particles and metal sulfate particles.
<3> The non-aqueous secondary battery according to <1> or <2>, wherein the average primary particle size of the inorganic particles contained in the insulating layer is 0.01 μm or more and less than 1.00 μm.
<4> The non-aqueous secondary battery according to any one of <1> to <3>, wherein the thickness of the insulating layer is 5 μm or more and 30 μm or less.
<5> The non-aqueous secondary battery according to any one of <1> to <4>, wherein the insulating layer has a porosity of 40% or more and less than 80%.
<6> The non-aqueous secondary battery according to any one of <1> to <5>, wherein the mass of the insulating layer per unit area is 4 g / m 2 or more and less than 40 g / m 2 .
<7> The non-aqueous secondary battery according to any one of <1> to <6>, which obtains an electromotive force by doping and dedoping lithium ions.

本開示によれば、信頼性の高い非水系二次電池が提供される。 According to the present disclosure, a highly reliable non-aqueous secondary battery is provided.

本開示の非水系二次電池の実施形態例を示す模式図である。It is a schematic diagram which shows the embodiment of the non-aqueous secondary battery of this disclosure.

以下に、本開示の実施形態について説明する。これらの説明及び実施例は実施形態を例示するものであり、実施形態の範囲を制限するものではない。 Hereinafter, embodiments of the present disclosure will be described. These explanations and examples illustrate the embodiments and do not limit the scope of the embodiments.

本開示において「A及び/又はB」は、「A及びBのうちの少なくとも1つ」と同義である。つまり、「A及び/又はB」は、Aだけであってもよいし、Bだけであってもよいし、A及びBの組み合わせであってもよい、という意味である。 In the present disclosure, "A and / or B" is synonymous with "at least one of A and B". That is, "A and / or B" means that it may be only A, it may be only B, or it may be a combination of A and B.

本開示において「~」を用いて示された数値範囲は、「~」の前後に記載される数値をそれぞれ最小値及び最大値として含む範囲を示す。
本開示中に段階的に記載されている数値範囲において、一つの数値範囲で記載された上限値又は下限値は、他の段階的な記載の数値範囲の上限値又は下限値に置き換えてもよい。また、本開示中に記載されている数値範囲において、その数値範囲の上限値又は下限値は、実施例に示されている値に置き換えてもよい。
The numerical range indicated by using "-" in the present disclosure indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively.
In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in another stepwise description. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

本開示において「工程」との語は、独立した工程だけでなく、他の工程と明確に区別できない場合であってもその工程の所期の目的が達成されれば、本用語に含まれる。 In the present disclosure, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.

本開示において実施形態を図面を参照して説明する場合、当該実施形態の構成は図面に示された構成に限定されない。また、各図における部材の大きさは概念的なものであり、部材間の大きさの相対的な関係はこれに限定されない。 When the embodiments are described in the present disclosure with reference to the drawings, the configuration of the embodiments is not limited to the configurations shown in the drawings. Further, the size of the members in each figure is conceptual, and the relative relationship between the sizes of the members is not limited to this.

本開示において組成物中の各成分の量について言及する場合、組成物中に各成分に該当する物質が複数種存在する場合には、特に断らない限り、組成物中に存在する当該複数種の物質の合計量を意味する。 When referring to the amount of each component in the composition in the present disclosure, if a plurality of substances corresponding to each component are present in the composition, unless otherwise specified, the plurality of species present in the composition. It means the total amount of substances.

本開示において各成分に該当する粒子は複数種含んでいてもよい。組成物中に各成分に該当する粒子が複数種存在する場合、各成分の粒径は、特に断らない限り、組成物中に存在する当該複数種の粒子の混合物についての値を意味する。 In the present disclosure, a plurality of types of particles corresponding to each component may be contained. When a plurality of particles corresponding to each component are present in the composition, the particle size of each component means a value for a mixture of the plurality of particles present in the composition, unless otherwise specified.

<非水系二次電池>
本開示の技術は、電解液に水を含まない二次電池、すなわち非水系二次電池に関する。本開示の非水系二次電池の実施形態の一例は、リチウムイオンのドープ及び脱ドープによって起電力を得るリチウムイオン二次電池である。
<Non-water-based secondary battery>
The technique of the present disclosure relates to a secondary battery that does not contain water in the electrolytic solution, that is, a non-aqueous secondary battery. An example of an embodiment of the non-aqueous secondary battery of the present disclosure is a lithium ion secondary battery that obtains an electromotive force by doping and dedoping lithium ions.

本開示の非水系二次電池は、正極と、負極と、絶縁層と、電解液とを備える。絶縁層は、一方の面が正極に接し他方の面が負極に接する単一層であり、ポリフッ化ビニリデン系樹脂及び無機粒子を含有する。絶縁層に含まれるポリフッ化ビニリデン系樹脂の重量平均分子量は90万以上150万以下であり、絶縁層に占める無機粒子の質量割合は50質量%以上90質量%未満である。 The non-aqueous secondary battery of the present disclosure includes a positive electrode, a negative electrode, an insulating layer, and an electrolytic solution. The insulating layer is a single layer in which one surface is in contact with the positive electrode and the other surface is in contact with the negative electrode, and contains a polyvinylidene fluoride-based resin and inorganic particles. The weight average molecular weight of the polyvinylidene fluoride-based resin contained in the insulating layer is 900,000 or more and 1.5 million or less, and the mass ratio of the inorganic particles in the insulating layer is 50% by mass or more and less than 90% by mass.

以下、「正極」と「負極」とを総称して「電極」という。また、「非水系二次電池」を単に「電池」ともいう。 Hereinafter, the "positive electrode" and the "negative electrode" are collectively referred to as an "electrode". Further, the "non-aqueous secondary battery" is also simply referred to as a "battery".

本開示の電池において絶縁層は、単一層であるゆえ、(1)絶縁層の内部に層間の境界がないので、絶縁層の電気抵抗を低く抑えることができ、電池の放電特性及びクーロン効率を高めることができ、(2)絶縁層の内部で層間剥離を起こすことがないので、電池のクーロン効率及びセル強度を高めることができる。 In the battery of the present disclosure, since the insulating layer is a single layer, (1) since there is no boundary between the layers inside the insulating layer, the electric resistance of the insulating layer can be suppressed low, and the discharge characteristics and the Coulomb efficiency of the battery can be improved. It can be enhanced, and (2) delamination does not occur inside the insulating layer, so that the Coulomb efficiency and cell strength of the battery can be enhanced.

本開示の電池において、絶縁層に含まれるポリフッ化ビニリデン系樹脂の重量平均分子量(Mw)は90万以上150万以下である。
ポリフッ化ビニリデン系樹脂のMwは、絶縁層の電気的絶縁性を高める観点と、絶縁層の空孔の閉塞を抑制してイオン透過性を良好にし、電池の放電特性を高める観点とから、90万以上である。ポリフッ化ビニリデン系樹脂のMwが90万未満であると、絶縁層の電気的絶縁性が不十分な場合がある。また、ポリフッ化ビニリデン系樹脂のMwが90万未満であると、電池の製造時に絶縁層に熱を印加した際に絶縁層の空孔が閉塞する場合があり、電池の放電特性が劣る。
ポリフッ化ビニリデン系樹脂のMwは、絶縁層と電極との接着を良好にして、電池のクーロン効率及びセル強度を高める観点から、150万以下である。ポリフッ化ビニリデン系樹脂のMwが150万超であると、電池の製造時に絶縁層に熱を印加した際にポリフッ化ビニリデン系樹脂が軟化しにくいゆえ絶縁層が電極に十分に接着せず、絶縁層と電極との間に空隙が生じる場合があり、その結果として、電池のクーロン効率及びセル強度が劣る。
In the battery of the present disclosure, the weight average molecular weight (Mw) of the polyvinylidene fluoride-based resin contained in the insulating layer is 900,000 or more and 1.5 million or less.
Mw of the polyvinylidene fluoride-based resin is 90 from the viewpoint of enhancing the electrical insulation of the insulating layer and suppressing the blockage of the pores of the insulating layer to improve the ion permeability and improve the discharge characteristics of the battery. It is over 10,000. If the Mw of the polyvinylidene fluoride-based resin is less than 900,000, the electrical insulating property of the insulating layer may be insufficient. Further, if the Mw of the polyvinylidene fluoride-based resin is less than 900,000, the pores of the insulating layer may be closed when heat is applied to the insulating layer during the manufacturing of the battery, and the discharge characteristics of the battery are inferior.
The Mw of the polyvinylidene fluoride-based resin is 1.5 million or less from the viewpoint of improving the adhesion between the insulating layer and the electrode and increasing the coulombic efficiency and cell strength of the battery. If the Mw of the polyvinylidene fluoride-based resin is more than 1.5 million, the polyvinylidene fluoride-based resin is difficult to soften when heat is applied to the insulating layer during battery manufacturing, so that the insulating layer does not sufficiently adhere to the electrode and is insulated. Voids may form between the layer and the electrodes, resulting in poor battery Coulomb efficiency and cell strength.

本開示の電池において、絶縁層に占める無機粒子の質量割合は50質量%以上90質量%未満である。
絶縁層に占める無機粒子の質量割合は、絶縁層の電気的絶縁性を高める観点と、絶縁層の空孔率を高めてイオン透過性を良好にし、電池の放電特性を高める観点とから、50質量%以上である。絶縁層に占める無機粒子の質量割合が50質量%未満であると、絶縁層の電気的絶縁性が不十分な場合がある。また、絶縁層に占める無機粒子の質量割合が50質量%未満であると、絶縁層の空孔率が十分でなく、電池の放電特性が劣る。
絶縁層に占める無機粒子の質量割合は、絶縁層の機械強度を高め、絶縁層と電極との接着を良好にして、電池のクーロン効率及びセル強度を高める観点から、90質量%未満である。絶縁層に占める無機粒子の質量割合が90質量%以上であると、絶縁層と電極との間に空隙が生じる場合があり、電池のクーロン効率及びセル強度が劣る。加えて、絶縁層に占める無機粒子の質量割合が90質量%以上であると、絶縁層がもろくなる場合がある。
In the battery of the present disclosure, the mass ratio of the inorganic particles in the insulating layer is 50% by mass or more and less than 90% by mass.
The mass ratio of the inorganic particles in the insulating layer is 50 from the viewpoint of enhancing the electrical insulating property of the insulating layer and increasing the pore ratio of the insulating layer to improve the ion permeability and the discharge characteristics of the battery. It is mass% or more. If the mass ratio of the inorganic particles to the insulating layer is less than 50% by mass, the electrical insulating property of the insulating layer may be insufficient. Further, when the mass ratio of the inorganic particles to the insulating layer is less than 50% by mass, the porosity of the insulating layer is not sufficient and the discharge characteristics of the battery are inferior.
The mass ratio of the inorganic particles to the insulating layer is less than 90% by mass from the viewpoint of increasing the mechanical strength of the insulating layer, improving the adhesion between the insulating layer and the electrode, and increasing the Coulomb efficiency and cell strength of the battery. If the mass ratio of the inorganic particles to the insulating layer is 90% by mass or more, voids may be formed between the insulating layer and the electrodes, and the Coulomb efficiency and cell strength of the battery are inferior. In addition, if the mass ratio of the inorganic particles to the insulating layer is 90% by mass or more, the insulating layer may become brittle.

以上の各構成の作用が相乗して、本開示の非水系二次電池は、放電特性、クーロン効率及びセル強度に優れ、したがって、信頼性が高い。 The actions of each of the above configurations are synergistic, and the non-aqueous secondary battery of the present disclosure is excellent in discharge characteristics, Coulomb efficiency and cell strength, and is therefore highly reliable.

以下、本開示の非水系二次電池が備える構成を詳細に説明する。 Hereinafter, the configuration included in the non-aqueous secondary battery of the present disclosure will be described in detail.

[正極]
正極は、例えば、集電体と、集電体の片面又は両面に配置された正極活物質層とを備える。
[Positive electrode]
The positive electrode includes, for example, a current collector and a positive electrode active material layer arranged on one side or both sides of the current collector.

正極の集電体としては、例えば、金属箔が挙げられる。金属箔としては、例えば、アルミニウム箔、チタン箔、ステンレス箔等が挙げられる。正極の集電体の厚さは、5μm~20μmが好ましい。 Examples of the current collector of the positive electrode include a metal foil. Examples of the metal foil include aluminum foil, titanium foil, stainless steel foil and the like. The thickness of the current collector of the positive electrode is preferably 5 μm to 20 μm.

正極活物質層は、正極活物質と樹脂とを含むことが好ましい。正極活物質層は、さらに導電助剤を含んでもよい。 The positive electrode active material layer preferably contains a positive electrode active material and a resin. The positive electrode active material layer may further contain a conductive auxiliary agent.

正極活物質としては、例えば、リチウム含有遷移金属酸化物が挙げられる。リチウム含有遷移金属酸化物としては、例えば、LiCoO、LiNiO、LiMn1/2Ni1/2、LiCo1/3Mn1/3Ni1/3、LiMn、LiFePO、LiCo1/2Ni1/2、LiAl1/4Ni3/4等が挙げられる。 Examples of the positive electrode active material include lithium-containing transition metal oxides. Examples of the lithium-containing transition metal oxides include LiCoO 2 , LiNiO 2 , LiMn 1/2 Ni 1/2 O 2 , LiCo 1/3 Mn 1/3 Ni 1/3 O 2 , LiMn 2 O 4 , and LiFePO 4 . , LiCo 1/2 Ni 1/2 O 2 , LiAl 1/4 Ni 3/4 O 2 , and the like.

樹脂としては、例えば、ポリフッ化ビニリデン系樹脂、アルギン酸塩等が挙げられる。 Examples of the resin include polyvinylidene fluoride-based resin, alginate and the like.

導電助剤としては、例えば、炭素材料が挙げられる。炭素材料としては、例えば、アセチレンブラック、ケッチェンブラック、炭素繊維等が挙げられる。 Examples of the conductive auxiliary agent include carbon materials. Examples of the carbon material include acetylene black, ketjen black, carbon fiber and the like.

[負極]
負極は、例えば、集電体と、集電体の片面又は両面に配置された負極活物質層とを備える。
[Negative electrode]
The negative electrode includes, for example, a current collector and a negative electrode active material layer arranged on one side or both sides of the current collector.

負極の集電体としては、例えば、金属箔が挙げられる。金属箔としては、例えば、銅箔、ニッケル箔、ステンレス箔等が挙げられる。負極の集電体の厚さは、5μm~20μmが好ましい。 Examples of the current collector of the negative electrode include a metal foil. Examples of the metal foil include copper foil, nickel foil, stainless steel foil and the like. The thickness of the current collector of the negative electrode is preferably 5 μm to 20 μm.

負極活物質層は、負極活物質と樹脂とを含むことが好ましい。負極活物質層は、さらに導電助剤を含んでもよい。 The negative electrode active material layer preferably contains a negative electrode active material and a resin. The negative electrode active material layer may further contain a conductive auxiliary agent.

負極活物質としては、例えば、リチウムイオンを電気化学的に吸蔵し得る材料が挙げられる。当該材料としては、例えば、炭素材料;ケイ素、ケイ素化合物、スズ、アルミニウム等とリチウムとの合金;ウッド合金;などが挙げられる。 Examples of the negative electrode active material include a material capable of electrochemically occluding lithium ions. Examples of the material include a carbon material; an alloy of silicon, a silicon compound, tin, aluminum and the like and lithium; a wood alloy; and the like.

樹脂としては、例えば、ポリフッ化ビニリデン系樹脂、スチレン-ブタジエン共重合体、カルボキシメチルセルロース等が挙げられる。 Examples of the resin include polyvinylidene fluoride-based resins, styrene-butadiene copolymers, carboxymethyl cellulose and the like.

導電助剤としては、例えば、炭素材料が挙げられる。炭素材料としては、例えば、アセチレンブラック、ケッチェンブラック、炭素繊維等が挙げられる。 Examples of the conductive auxiliary agent include carbon materials. Examples of the carbon material include acetylene black, ketjen black, carbon fiber and the like.

[絶縁層]
絶縁層は、内部に多数の微細孔を有し、これら微細孔が連結された多孔構造となっており、一方の面から他方の面へと気体あるいは液体が通過可能となっている単一層である。
[Insulation layer]
The insulating layer is a single layer that has a large number of micropores inside and has a porous structure in which these micropores are connected so that gas or liquid can pass from one surface to the other. be.

絶縁層の実施形態の一例は、一方の面が正極活物質層に接し、他方の面が負極活物質層に接する。 In one example of the insulating layer embodiment, one surface is in contact with the positive electrode active material layer and the other surface is in contact with the negative electrode active material layer.

絶縁層は、ポリフッ化ビニリデン系樹脂と無機粒子とを含有する。絶縁層は、ポリフッ化ビニリデン系樹脂以外のその他の樹脂、有機フィラー等を含んでもよい。 The insulating layer contains a polyvinylidene fluoride-based resin and inorganic particles. The insulating layer may contain a resin other than the polyvinylidene fluoride-based resin, an organic filler, and the like.

-ポリフッ化ビニリデン系樹脂-
ポリフッ化ビニリデン系樹脂としては、例えば、フッ化ビニリデンの単独重合体(即ちポリフッ化ビニリデン);フッ化ビニリデンと、ヘキサフルオロプロピレン、テトラフルオロエチレン、トリフルオロエチレン、クロロトリフルオロエチレン、フッ化ビニル、トリクロロエチレン等の含ハロゲン単量体との共重合体;これらの混合物;が挙げられる。ポリフッ化ビニリデン系樹脂は、1種を単独で使用してもよく、2種以上を組み合わせて使用してもよい。
-Polyvinylidene fluoride resin-
Examples of the polyvinylidene fluoride-based resin include homopolymers of vinylidene fluoride (that is, polyvinylidene fluoride); vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, vinyl fluoride, and the like. Polymers with halogen-containing monomers such as trichloroethylene; mixtures thereof; can be mentioned. As the polyvinylidene fluoride-based resin, one type may be used alone, or two or more types may be used in combination.

ポリフッ化ビニリデン系樹脂としては、電極に対する絶縁層の接着性の観点から、フッ化ビニリデン(VDF)とヘキサフルオロプロピレン(HFP)との共重合体(VDF-HFP共重合体)が好ましい。本開示においてVDF-HFP共重合体には、VDFとHFPのみを重合した共重合体(VDF-HFP二元共重合体という。)、及び、VDFとHFPと他の単量体を重合した共重合体のいずれも含まれる。ここでの他の単量体としては、例えば、テトラフルオロエチレン、トリフルオロエチレン、クロロトリフルオロエチレン、フッ化ビニル、トリクロロエチレン等の含ハロゲン単量体が挙げられる。 As the polyvinylidene fluoride-based resin, a copolymer (VDF-HFP copolymer) of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) is preferable from the viewpoint of adhesiveness of the insulating layer to the electrode. In the present disclosure, the VDF-HFP copolymer includes a copolymer obtained by polymerizing only VDF and HFP (referred to as a VDF-HFP binary copolymer), and a copolymer obtained by polymerizing VDF, HFP and other monomers. Any of the polymers are included. Examples of other monomers here include halogen-containing monomers such as tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, vinyl fluoride, and trichlorethylene.

VDF-HFP共重合体は、HFP単位の含有量を増減することによって、当該共重合体の結晶性、電極活物質層に対する接着性、電解液に対する耐溶解性などを適度な範囲に制御できる。
VDF-HFP共重合体において、全重合成分に占めるHFPの割合は、1.0モル%超が好ましく、1.5モル%超がより好ましく、2.0モル%以上が更に好ましく、2.2モル%以上が更に好ましく、7.0モル%以下が好ましく、6.5モル%以下がより好ましく、6.0モル%以下が更に好ましい。
By increasing or decreasing the content of the HFP unit, the VDF-HFP copolymer can control the crystallinity of the copolymer, the adhesiveness to the electrode active material layer, the solubility resistance to the electrolytic solution, and the like within an appropriate range.
In the VDF-HFP copolymer, the ratio of HFP to the total polymer components is preferably more than 1.0 mol%, more preferably more than 1.5 mol%, still more preferably 2.0 mol% or more, 2.2. More preferably, it is more than mol%, more preferably 7.0 mol% or less, more preferably 6.5 mol% or less, still more preferably 6.0 mol% or less.

絶縁層に含まれるポリフッ化ビニリデン系樹脂の重量平均分子量(Mw)は90万~150万である。
ポリフッ化ビニリデン系樹脂のMwが90万以上であると、絶縁層の電気的絶縁性が良好であり、また、電池の製造時に絶縁層に熱を印加した際に、絶縁層の空孔の閉塞が起きにくい。この観点から、ポリフッ化ビニリデン系樹脂のMwは、90万以上であり、100万以上が好ましく、110万以上がより好ましい。
ポリフッ化ビニリデン系樹脂のMwが150万以下であると、電池の製造時に絶縁層に熱を印加した際に、絶縁層と電極とが良好に接着し、絶縁層と電極との間に空隙が生じにくい。この観点から、ポリフッ化ビニリデン系樹脂のMwは、150万以下であり、140万以下が好ましく、130万以下がより好ましい。
The weight average molecular weight (Mw) of the polyvinylidene fluoride-based resin contained in the insulating layer is 900,000 to 1,500,000.
When the Mw of the polyvinylidene fluoride-based resin is 900,000 or more, the electrical insulation of the insulating layer is good, and when heat is applied to the insulating layer during manufacturing of the battery, the pores of the insulating layer are closed. Is hard to occur. From this viewpoint, the Mw of the polyvinylidene fluoride-based resin is 900,000 or more, preferably 1 million or more, and more preferably 1.1 million or more.
When the Mw of the polyvinylidene fluoride resin is 1.5 million or less, the insulating layer and the electrode adhere well when heat is applied to the insulating layer during the manufacturing of the battery, and a gap is formed between the insulating layer and the electrode. It is unlikely to occur. From this viewpoint, the Mw of the polyvinylidene fluoride-based resin is 1.5 million or less, preferably 1.4 million or less, and more preferably 1.3 million or less.

絶縁層に占めるポリフッ化ビニリデン系樹脂の質量割合は、10質量%~50質量%が好ましく、15質量%~50質量%がより好ましく、20質量%~50質量%が更に好ましい。 The mass ratio of the polyvinylidene fluoride-based resin to the insulating layer is preferably 10% by mass to 50% by mass, more preferably 15% by mass to 50% by mass, still more preferably 20% by mass to 50% by mass.

絶縁層に含まれるポリフッ化ビニリデン系樹脂の含有量は、絶縁層に含まれる全樹脂の全量に対して、85質量%~100質量%が好ましく、90質量%~100質量%がより好ましく、95質量%~100質量%が更に好ましい。 The content of the polyvinylidene fluoride-based resin contained in the insulating layer is preferably 85% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, and 95% by mass, based on the total amount of the total resin contained in the insulating layer. More preferably, it is from% by mass to 100% by mass.

-その他の樹脂-
絶縁層は、ポリフッ化ビニリデン系樹脂以外のその他の樹脂を含んでいてもよい。その他の樹脂としては、例えば、アクリル系樹脂、フッ素系ゴム、スチレン-ブタジエン共重合体、ビニルニトリル化合物(アクリロニトリル、メタクリロニトリル等)の単独重合体又は共重合体、カルボキシメチルセルロース、ヒドロキシアルキルセルロース、ポリビニルアルコール、ポリビニルブチラール、ポリビニルピロリドン、ポリエーテル(ポリエチレンオキサイド、ポリプロピレンオキサイド等)、ポリアミド、全芳香族ポリアミド(アラミドともいう。)、ポリイミド、ポリアミドイミド、ポリスルホン、ポリケトン、ポリエーテルケトン、ポリエーテルスルホン、ポリエーテルイミド、及びこれらの混合物が挙げられる。
-Other resins-
The insulating layer may contain other resins other than the polyvinylidene fluoride-based resin. Examples of other resins include acrylic resins, fluororubbers, styrene-butadiene copolymers, homopolymers or copolymers of vinylnitrile compounds (acrylonitrile, methacrylonitrile, etc.), carboxymethyl cellulose, hydroxyalkyl cellulose, and the like. Polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, polyether (polyethylene oxide, polypropylene oxide, etc.), polyamide, total aromatic polyamide (also referred to as aramid), polyimide, polyamideimide, polysulfone, polyketone, polyetherketone, polyethersulfone, Polyetherimides and mixtures thereof can be mentioned.

絶縁層に含まれるポリフッ化ビニリデン系樹脂以外のその他の樹脂の含有量は、絶縁層に含まれる全樹脂の全量に対して、0質量%~15質量%が好ましく、0質量%~10質量%がより好ましく、0質量%~5質量%が更に好ましい。 The content of the resin other than the polyvinylidene fluoride-based resin contained in the insulating layer is preferably 0% by mass to 15% by mass, preferably 0% by mass to 10% by mass, based on the total amount of the total resin contained in the insulating layer. Is more preferable, and 0% by mass to 5% by mass is further preferable.

-無機粒子-
無機粒子の粒子形状に限定はなく、球状、板状、針状、不定形状のいずれでもよい。無機粒子は、電池の短絡抑制の観点又は絶縁層に緻密に充填されやすい観点から、球状又は板状の粒子であることが好ましい。
-Inorganic particles-
The particle shape of the inorganic particles is not limited, and may be spherical, plate-shaped, needle-shaped, or indefinite. The inorganic particles are preferably spherical or plate-shaped particles from the viewpoint of suppressing short circuits in the battery or from the viewpoint of being easily filled in the insulating layer.

無機粒子の材質は制限されるものではない。無機粒子としては、金属水酸化物粒子、金属硫酸塩粒子、金属酸化物粒子、金属炭酸塩粒子、金属窒化物粒子、金属フッ化物粒子、粘土鉱物の粒子等が挙げられる。無機粒子は、1種を単独で使用してもよく、材質が異なる2種以上を組み合わせて使用してもよい。 The material of the inorganic particles is not limited. Examples of the inorganic particles include metal hydroxide particles, metal sulfate particles, metal oxide particles, metal carbonate particles, metal nitride particles, metal fluoride particles, and clay mineral particles. As the inorganic particles, one kind may be used alone, or two or more kinds of different materials may be used in combination.

金属水酸化物粒子としては、例えば、水酸化マグネシウム(Mg(OH))、水酸化アルミニウム(Al(OH))、水酸化カルシウム(Ca(OH))、水酸化ニッケル(Ni(OH))等の粒子が挙げられる。金属水酸化物粒子としては、水酸化マグネシウム粒子が好ましい。 Examples of the metal hydroxide particles include magnesium hydroxide (Mg (OH) 2 ), aluminum hydroxide (Al (OH) 3 ), calcium hydroxide (Ca (OH) 2 ), and nickel hydroxide (Ni (OH) 2). ) 2 ) and other particles can be mentioned. As the metal hydroxide particles, magnesium hydroxide particles are preferable.

金属硫酸塩粒子としては、例えば、硫酸バリウム(BaSO)、硫酸ストロンチウム(SrSO)、硫酸カルシウム(CaSO)、硫酸カルシウム二水和物(CaSO・2HO)、ミョウバン石(KAl(SO(OH))、ジャロサイト(KFe(SO(OH))等の粒子が挙げられる。金属硫酸塩粒子としては、硫酸バリウム粒子が好ましい。 Examples of the metal sulfate particles include barium sulfate (BaSO 4 ), strontium sulfate (SrSO 4 ), calcium sulfate (CaSO 4 ), calcium sulfate dihydrate (CaSO 4.2H 2 O), and myoban stone (KAl 3 ). Particles such as (SO 4 ) 2 (OH) 6 ) and jarosite (KFe 3 (SO 4 ) 2 (OH) 6 ) can be mentioned. As the metal sulfate particles, barium sulfate particles are preferable.

金属酸化物粒子としては、例えば、酸化マグネシウム、アルミナ(Al)、ベーマイト(AlOOH、アルミナ1水和物)、チタニア(TiO)、シリカ(SiO)、ジルコニア(ZrO)、チタン酸バリウム(BaTiO)、酸化亜鉛等の粒子が挙げられる。 Examples of the metal oxide particles include magnesium oxide, alumina (Al 2 O 3 ), boehmite (AlOOH, alumina monohydrate), titania (TiO 2 ), silica (SiO 2 ), zirconia (ZrO 2 ), and titanium. Examples include particles such as barium acid (BaTIO 3 ) and zinc oxide.

金属炭酸塩粒子としては、例えば、炭酸マグネシウム、炭酸カルシウム等の粒子が挙げられる。 Examples of the metal carbonate particles include particles such as magnesium carbonate and calcium carbonate.

金属窒化物粒子としては、例えば、窒化マグネシウム、窒化アルミニウム、窒化カルシウム、窒化チタン等の粒子が挙げられる。 Examples of the metal nitride particles include particles such as magnesium nitride, aluminum nitride, calcium nitride, and titanium nitride.

金属フッ化物粒子としては、例えば、フッ化マグネシウム、フッ化カルシウム等の粒子が挙げられる。 Examples of the metal fluoride particles include particles such as magnesium fluoride and calcium fluoride.

粘土鉱物の粒子としては、例えば、ケイ酸カルシウム、リン酸カルシウム、アパタイト、タルク等の粒子が挙げられる。 Examples of the clay mineral particles include particles such as calcium silicate, calcium phosphate, apatite, and talc.

無機粒子としては、難燃性の観点から、金属水酸化物粒子が好ましく、電解液に対して安定でありガス発生を抑制する観点から、金属硫酸塩粒子が好ましい。無機粒子は、金属水酸化物粒子及び金属硫酸塩粒子からなる群から選ばれる少なくとも1種を含むことが好ましい。 As the inorganic particles, metal hydroxide particles are preferable from the viewpoint of flame retardancy, and metal sulfate particles are preferable from the viewpoint of being stable with respect to the electrolytic solution and suppressing gas generation. The inorganic particles preferably contain at least one selected from the group consisting of metal hydroxide particles and metal sulfate particles.

絶縁層に含まれる無機粒子の平均一次粒径は、絶縁層を多孔質化してイオン透過性を高める観点から、0.01μm以上が好ましく、0.02μm以上がより好ましく、0.03μm以上が更に好ましい。
絶縁層に含まれる無機粒子の平均一次粒径は、絶縁層を薄膜化して電池のエネルギー密度を高める観点から、1.00μm未満が好ましく、0.95μm未満がより好ましく、0.90μm未満が更に好ましい。
The average primary particle size of the inorganic particles contained in the insulating layer is preferably 0.01 μm or more, more preferably 0.02 μm or more, and further preferably 0.03 μm or more, from the viewpoint of making the insulating layer porous and enhancing ion permeability. preferable.
The average primary particle size of the inorganic particles contained in the insulating layer is preferably less than 1.00 μm, more preferably less than 0.95 μm, and further less than 0.90 μm from the viewpoint of thinning the insulating layer and increasing the energy density of the battery. preferable.

無機粒子として平均一次粒径が異なる無機粒子を2種以上併用してもよく、その場合、それぞれの平均一次粒径が上記範囲であることが好ましく、且つ、全体の平均一次粒径が上記範囲であることが好ましい。 Two or more kinds of inorganic particles having different average primary particle sizes may be used in combination as the inorganic particles. In that case, the average primary particle size of each is preferably in the above range, and the overall average primary particle size is in the above range. Is preferable.

無機粒子の平均一次粒径は、走査型電子顕微鏡(SEM)による観察において無作為に選んだ一次粒子100個の長径を計測し、100個の長径を平均することで求める。無機粒子の一次粒径が小さくSEMでは一次粒子の長径が測定困難な場合及び/又は無機粒子の凝集が顕著でありSEMでは一次粒子の長径が測定困難な場合は、無機粒子のBET比表面積(m/g)を測定し、無機粒子を真球と仮定して、下記の式に従い平均一次粒径を求める。
平均一次粒径(μm)=6÷[比重(g/cm)×BET比表面積(m/g)]
BET比表面積(m/g)は、窒素ガスを用いたガス吸着法であってBET多点法により求める。ガス吸着法による測定の際、窒素ガスは、無機粒子に液体窒素の沸点(-196℃)で吸着させる。
The average primary particle size of the inorganic particles is determined by measuring the major axis of 100 primary particles randomly selected in observation with a scanning electron microscope (SEM) and averaging the major axis of 100 particles. If the primary particle size of the inorganic particles is small and it is difficult to measure the major axis of the primary particles with SEM and / or if the aggregation of the inorganic particles is remarkable and the major axis of the primary particles is difficult to measure with SEM, the BET specific surface area of the inorganic particles ( m 2 / g) is measured, assuming that the inorganic particles are true spheres, and the average primary particle size is obtained according to the following formula.
Average primary particle size (μm) = 6 ÷ [specific gravity (g / cm 3 ) x BET specific surface area (m 2 / g)]
The BET specific surface area (m 2 / g) is a gas adsorption method using nitrogen gas and is obtained by the BET multipoint method. During the measurement by the gas adsorption method, nitrogen gas is adsorbed on inorganic particles at the boiling point (-196 ° C.) of liquid nitrogen.

SEMによる観察又はBET比表面積の測定に供する試料は、絶縁層を形成する材料である無機粒子、又は、絶縁層から取り出した無機粒子である。絶縁層から無機粒子を取り出す方法に制限はなく、例えば、絶縁層を800℃程度に加熱してバインダ樹脂を消失させ無機粒子を取り出す方法、絶縁層を有機溶剤に浸漬して有機溶剤でバインダ樹脂を溶解させ無機粒子を取り出す方法などが挙げられる。 The sample to be used for observation by SEM or measurement of the BET specific surface area is inorganic particles which are materials for forming the insulating layer or inorganic particles taken out from the insulating layer. There is no limitation on the method of extracting the inorganic particles from the insulating layer, for example, a method of heating the insulating layer to about 800 ° C. to eliminate the binder resin and extracting the inorganic particles, a method of immersing the insulating layer in an organic solvent and using an organic solvent for the binder resin. A method of dissolving the inorganic particles and taking out the inorganic particles can be mentioned.

絶縁層に占める無機粒子の質量割合は、絶縁層の電気的絶縁性を高める観点と、絶縁層の空孔率を高めてイオン透過性を良好にし、電池の放電特性を高める観点とから、50質量%以上であり、55質量%以上が好ましく、60質量%以上がより好ましい。
絶縁層に占める無機粒子の質量割合は、絶縁層と電極との接着を良好にして、電池のクーロン効率及びセル強度を高める観点から、90質量%未満であり、88質量%未満が好ましく、85質量%未満がより好ましい。
The mass ratio of the inorganic particles in the insulating layer is 50 from the viewpoint of enhancing the electrical insulating property of the insulating layer and increasing the pore ratio of the insulating layer to improve the ion permeability and the discharge characteristics of the battery. It is 5% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more.
The mass ratio of the inorganic particles in the insulating layer is less than 90% by mass, preferably less than 88% by mass, preferably 85, from the viewpoint of improving the adhesion between the insulating layer and the electrode and increasing the coulombic efficiency and cell strength of the battery. More preferably less than% by weight.

-有機フィラー-
有機フィラーとしては、例えば、架橋ポリ(メタ)アクリル酸、架橋ポリ(メタ)アクリル酸エステル、架橋ポリシリコーン、架橋ポリスチレン、架橋ポリジビニルベンゼン、スチレン-ジビニルベンゼン共重合体架橋物、メラミン樹脂、フェノール樹脂、ベンゾグアナミン-ホルムアルデヒド縮合物等の架橋高分子からなる粒子;ポリスルホン、ポリアクリロニトリル、アラミド、ポリアセタール等の耐熱性高分子からなる粒子;などが挙げられる。これら有機フィラーは、1種を単独で使用してもよく、2種以上を組み合わせて使用してもよい。本開示において「(メタ)アクリル」との表記は「アクリル」及び「メタクリル」のいずれでもよいことを意味する。
-Organic filler-
Examples of the organic filler include crosslinked poly (meth) acrylic acid, crosslinked poly (meth) acrylic acid ester, crosslinked polysilicone, crosslinked polystyrene, crosslinked polydivinylbenzene, styrene-divinylbenzene copolymer crosslinked product, melamine resin, and phenol. Particles made of crosslinked polymers such as resins and benzoguanamine-formaldehyde condensates; particles made of heat-resistant polymers such as polysulfone, polyacrylonitrile, aramid, and polyacetal; and the like. These organic fillers may be used alone or in combination of two or more. In the present disclosure, the notation "(meth) acrylic" means that it may be either "acrylic" or "methacrylic".

-その他の成分-
絶縁層は、界面活性剤等の分散剤、湿潤剤、消泡剤、pH調整剤などの添加剤を含んでいてもよい。これらは、絶縁層を形成するための塗工液に添加されることがある。
-Other ingredients-
The insulating layer may contain an additive such as a dispersant such as a surfactant, a wetting agent, a defoaming agent, and a pH adjuster. These may be added to the coating liquid for forming the insulating layer.

[絶縁層の特性]
絶縁層の厚さは、絶縁層の電気的絶縁性及び機械的強度の観点から、5μm以上が好ましく、イオン透過性及び電池のエネルギー密度の観点から、30μm以下が好ましく、25μm以下がより好ましく、20μm以下が更に好ましい。
[Characteristics of insulating layer]
The thickness of the insulating layer is preferably 5 μm or more from the viewpoint of electrical insulation and mechanical strength of the insulating layer, preferably 30 μm or less, more preferably 25 μm or less from the viewpoint of ion permeability and energy density of the battery. 20 μm or less is more preferable.

絶縁層の単位面積当たりの質量は、絶縁層の電気的絶縁性及び機械的強度の観点から、4g/m以上が好ましく、8g/m以上がより好ましく、10g/m以上が更に好ましく、イオン透過性及び電池のエネルギー密度の観点から、40g/m未満が好ましく、35g/m未満がより好ましく、30g/m未満が更に好ましい。 The mass per unit area of the insulating layer is preferably 4 g / m 2 or more, more preferably 8 g / m 2 or more, still more preferably 10 g / m 2 or more, from the viewpoint of electrical insulation and mechanical strength of the insulating layer. From the viewpoint of ion permeability and energy density of the battery, less than 40 g / m 2 is preferable, less than 35 g / m 2 is more preferable, and less than 30 g / m 2 is further preferable.

絶縁層の空孔率は、イオン透過性の観点から、40%以上が好ましく、45%以上がより好ましく、50%以上が更に好ましく、絶縁層の電気的絶縁性及び機械的強度の観点から、80%未満が好ましく、75%未満がより好ましく、70%未満が更に好ましい。 The porosity of the insulating layer is preferably 40% or more, more preferably 45% or more, further preferably 50% or more from the viewpoint of ion permeability, and further preferably 50% or more, from the viewpoint of electrical insulation and mechanical strength of the insulating layer. Less than 80% is preferred, less than 75% is more preferred, and less than 70% is even more preferred.

絶縁層の空孔率ε(%)は、下記の方法で求める。
絶縁層の単位面積当たりの質量を絶縁層の厚さで除算し、絶縁層の嵩密度d1を求める。絶縁層の真密度d0を、下記の式(1)から算出する。そして、絶縁層の空孔率ε(%)を、下記の式(2)から算出する。
式(1)・・・d0=100/(絶縁層の樹脂固形分比/樹脂の密度+絶縁層の無機粒子固形分比/無機粒子の密度)
式(2)・・・ε=(1-d1/d0)×100
The porosity ε (%) of the insulating layer is obtained by the following method.
The mass per unit area of the insulating layer is divided by the thickness of the insulating layer to obtain the bulk density d1 of the insulating layer. The true density d0 of the insulating layer is calculated from the following equation (1). Then, the porosity ε (%) of the insulating layer is calculated from the following equation (2).
Equation (1) ... d0 = 100 / (resin solid content ratio of insulating layer / density of resin + solid content ratio of inorganic particles in insulating layer / density of inorganic particles)
Equation (2) ... ε = (1-d1 / d0) × 100

[電解液]
電解液としては、例えば、リチウム塩を非水系溶媒に溶解した溶液が挙げられる。
リチウム塩としては、例えば、LiPF、LiBF、LiClO等が挙げられる。
非水系溶媒としては、例えば、エチレンカーボネート、プロピレンカーボネート、フルオロエチレンカーボネート、ジフルオロエチレンカーボネート、ビニレンカーボネート等の環状カーボネート;ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネート、及びそのフッ素置換体等の鎖状カーボネート;γ-ブチロラクトン、γ-バレロラクトン等の環状エステル;などが挙げられる。これらは単独で用いても混合して用いてもよい。
[Electrolytic solution]
Examples of the electrolytic solution include a solution in which a lithium salt is dissolved in a non-aqueous solvent.
Examples of the lithium salt include LiPF 6 , LiBF 4 , LiClO 4 , and the like.
Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and vinylene carbonate; and chain carbonates such as dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and fluorine-substituted products thereof; Cyclic esters such as γ-butyrolactone and γ-valerolactone; and the like. These may be used alone or in combination.

リチウムイオン二次電池の電解液としては、環状カーボネートと鎖状カーボネートとを環状カーボネート:鎖状カーボネート=20:80~40:60(質量比)で混合し、リチウム塩を0.5mol/L~1.5mol/Lの範囲にて溶解した溶液が好適である。 As the electrolytic solution of the lithium ion secondary battery, cyclic carbonate and chain carbonate are mixed at a cyclic carbonate: chain carbonate = 20:80 to 40:60 (mass ratio), and the lithium salt is 0.5 mol / L or more. A solution dissolved in the range of 1.5 mol / L is suitable.

図1は、本開示の非水系二次電池の実施形態の一例である。図1は、電池の断面を模式的に示した図である。図1は、非水系二次電池の実施形態の例示であり、実施形態を限定するものではない。 FIG. 1 is an example of an embodiment of the non-aqueous secondary battery of the present disclosure. FIG. 1 is a diagram schematically showing a cross section of a battery. FIG. 1 is an example of an embodiment of a non-aqueous secondary battery, and does not limit the embodiment.

図1に示す非水系二次電池100は、電池素子10と、電解液50と、外装材90とを備える。外装材90の内部に電池素子10及び電解液50が収容されている。 The non-aqueous secondary battery 100 shown in FIG. 1 includes a battery element 10, an electrolytic solution 50, and an exterior material 90. The battery element 10 and the electrolytic solution 50 are housed inside the exterior material 90.

電池素子10は、正極20と絶縁層30と負極40とを備える。電池素子10は、正極20と絶縁層30と負極40とがこの順に少なくとも1層ずつ積層した構造を有する。 The battery element 10 includes a positive electrode 20, an insulating layer 30, and a negative electrode 40. The battery element 10 has a structure in which a positive electrode 20, an insulating layer 30, and a negative electrode 40 are laminated in this order by at least one layer.

正極20は、正極集電体22と、正極集電体22の両面に配置された正極活物質層24とを備える。正極集電体22の一端は、正極活物質層24が配置されておらず、例えば、タブの形状になっている。 The positive electrode 20 includes a positive electrode current collector 22 and a positive electrode active material layer 24 arranged on both sides of the positive electrode current collector 22. The positive electrode active material layer 24 is not arranged at one end of the positive electrode current collector 22, and is in the shape of a tab, for example.

負極40は、負極集電体42と、負極集電体42の両面に配置された負極活物質層44とを備える。負極集電体42の一端は、負極活物質層44が配置されておらず、例えば、タブの形状になっている。 The negative electrode 40 includes a negative electrode current collector 42 and negative electrode active material layers 44 arranged on both sides of the negative electrode current collector 42. The negative electrode active material layer 44 is not arranged at one end of the negative electrode current collector 42, and is in the shape of a tab, for example.

絶縁層30は、一方の面が正極活物質層24に接し、他方の面が負極活物質層44に接している。絶縁層30は、多孔質層であり、絶縁層30には電解液50が含浸している。 One surface of the insulating layer 30 is in contact with the positive electrode active material layer 24, and the other surface is in contact with the negative electrode active material layer 44. The insulating layer 30 is a porous layer, and the insulating layer 30 is impregnated with the electrolytic solution 50.

外装材90としては、金属缶、アルミニウムラミネートフィルム製パック等が挙げられる。 Examples of the exterior material 90 include metal cans, aluminum laminated film packs, and the like.

非水系二次電池100は、外装材90の外部に正極端子(図示せず)と負極端子(図示せず)とを備える。正極端子には、複数の正極集電体22が連結し、負極端子には、複数の負極集電体42が連結している。正極端子と正極集電体22との間(又は、負極端子と負極集電体42との間)には、リードタブが介在していてもよい。 The non-aqueous secondary battery 100 includes a positive electrode terminal (not shown) and a negative electrode terminal (not shown) outside the exterior material 90. A plurality of positive electrode current collectors 22 are connected to the positive electrode terminals, and a plurality of negative electrode current collectors 42 are connected to the negative electrode terminals. A lead tab may be interposed between the positive electrode terminal and the positive electrode current collector 22 (or between the negative electrode terminal and the negative electrode current collector 42).

非水系二次電池100の形状としては、例えば、角型、円筒型、コイン型などが挙げられる。 Examples of the shape of the non-aqueous secondary battery 100 include a square type, a cylindrical type, and a coin type.

[非水系二次電池の製造方法]
本開示の非水系二次電池は、例えば、下記の製造方法によって製造可能である。すなわち、
絶縁層を支持体上に湿式塗工法又は乾式塗工法で形成する工程Aと、
正極と負極との間に絶縁層を配置した積層体を製造する工程Bと、
積層体にウェットヒートプレス及び/又はドライヒートプレスを行う工程Cと、
を含む製造方法である。
[Manufacturing method of non-aqueous secondary battery]
The non-aqueous secondary battery of the present disclosure can be manufactured by, for example, the following manufacturing method. That is,
Step A of forming an insulating layer on a support by a wet coating method or a dry coating method, and
Step B of manufacturing a laminate in which an insulating layer is arranged between a positive electrode and a negative electrode, and
Step C of performing a wet heat press and / or a dry heat press on the laminate,
It is a manufacturing method including.

-工程A-
支持体とは、絶縁層形成用の塗工液を塗工するシート状の材料を意味する。支持体としては、例えば、正極、負極、剥離シートが挙げられる。
-Process A-
The support means a sheet-like material to which a coating liquid for forming an insulating layer is applied. Examples of the support include a positive electrode, a negative electrode, and a release sheet.

湿式塗工法とは、塗工層を凝固液中で固化させる方法を意味し、乾式塗工法とは、塗工層を乾燥させて固化させる方法を意味する。 The wet coating method means a method of solidifying the coating layer in a coagulating liquid, and the dry coating method means a method of drying and solidifying the coating layer.

工程Aの実施形態例として、絶縁層を正極の活物質層上に湿式塗工法又は乾式塗工法で形成する工程;絶縁層を負極の活物質層上に湿式塗工法又は乾式塗工法で形成する工程;絶縁層を剥離シート上に湿式塗工法又は乾式塗工法で形成する工程;が挙げられる。 As an example of the embodiment of step A, a step of forming an insulating layer on an active material layer of a positive electrode by a wet coating method or a dry coating method; forming an insulating layer on an active material layer of a negative electrode by a wet coating method or a dry coating method. A step; a step of forming an insulating layer on a release sheet by a wet coating method or a dry coating method;

以下、絶縁層を支持体上に湿式塗工法で形成する実施形態例を説明する。 Hereinafter, an example of an embodiment in which the insulating layer is formed on the support by a wet coating method will be described.

湿式塗工法の実施形態例として、樹脂及び無機粒子を含有する塗工液を支持体上に塗工し、凝固液に浸漬して塗工層を固化させ、凝固液から引き揚げ水洗及び乾燥を行う形態が挙げられる。 As an example of an embodiment of the wet coating method, a coating liquid containing a resin and inorganic particles is applied onto a support, immersed in a coagulating liquid to solidify the coating layer, and then withdrawn from the coagulating liquid to be washed with water and dried. The form is mentioned.

絶縁層形成用の塗工液は、樹脂及び無機粒子を溶媒に溶解又は分散させて作製する。塗工液には、必要に応じて、樹脂及び無機粒子以外のその他の成分を溶解又は分散させる。 The coating liquid for forming the insulating layer is prepared by dissolving or dispersing the resin and the inorganic particles in a solvent. If necessary, the coating liquid dissolves or disperses other components other than the resin and inorganic particles.

塗工液の調製に用いる溶媒は、樹脂を溶解する溶媒(以下、「良溶媒」ともいう。)を含む。良溶媒としては、N-メチルピロリドン、ジメチルアセトアミド、ジメチルホルムアミド等の極性アミド溶媒が挙げられる。 The solvent used for preparing the coating liquid includes a solvent that dissolves the resin (hereinafter, also referred to as “good solvent”). Examples of the good solvent include polar amide solvents such as N-methylpyrrolidone, dimethylacetamide and dimethylformamide.

塗工液の調製に用いる溶媒は、良好な多孔構造を有する絶縁層を形成する観点から、相分離を誘発させる相分離剤を含むことが好ましい。したがって、塗工液の調製に用いる溶媒は、良溶媒と相分離剤との混合溶媒であることが好ましい。相分離剤は、塗工に適切な粘度が確保できる範囲の量で良溶媒と混合することが好ましい。相分離剤としては、水、メタノール、エタノール、プロピルアルコール、ブチルアルコール、ブタンジオール、エチレングリコール、プロピレングリコール、トリプロピレングリコール等が挙げられる。 The solvent used for preparing the coating liquid preferably contains a phase separation agent that induces phase separation from the viewpoint of forming an insulating layer having a good porous structure. Therefore, the solvent used for preparing the coating liquid is preferably a mixed solvent of a good solvent and a phase separation agent. The phase separation agent is preferably mixed with a good solvent in an amount that can secure an appropriate viscosity for coating. Examples of the phase separation agent include water, methanol, ethanol, propyl alcohol, butyl alcohol, butane diol, ethylene glycol, propylene glycol, tripropylene glycol and the like.

塗工液の調製に用いる溶媒としては、良好な多孔構造を有する絶縁層を形成する観点から、良溶媒と相分離剤との混合溶媒であって、良溶媒を60質量%以上含み、相分離剤を5質量%~40質量%含む混合溶媒が好ましい。 The solvent used for preparing the coating liquid is a mixed solvent of a good solvent and a phase separation agent from the viewpoint of forming an insulating layer having a good porous structure, and contains 60% by mass or more of the good solvent for phase separation. A mixed solvent containing 5% by mass to 40% by mass of the agent is preferable.

塗工液の樹脂濃度は、良好な多孔構造を有する絶縁層を形成する観点から、3質量%~10質量%であることが好ましい。塗工液の無機粒子濃度は、良好な多孔構造を有する絶縁層を形成する観点から、2質量%~50質量%であることが好ましい。 The resin concentration of the coating liquid is preferably 3% by mass to 10% by mass from the viewpoint of forming an insulating layer having a good porous structure. The concentration of inorganic particles in the coating liquid is preferably 2% by mass to 50% by mass from the viewpoint of forming an insulating layer having a good porous structure.

塗工液は、界面活性剤等の分散剤、湿潤剤、消泡剤、pH調整剤等を含有していてもよい。これらの添加剤は、非水系二次電池の使用範囲において電気化学的に安定で電池内反応を阻害しないものであれば、絶縁層に残存するものであってもよい。 The coating liquid may contain a dispersant such as a surfactant, a wetting agent, an antifoaming agent, a pH adjusting agent and the like. These additives may remain in the insulating layer as long as they are electrochemically stable in the range of use of the non-aqueous secondary battery and do not inhibit the reaction in the battery.

支持体への塗工液の塗工手段としては、マイヤーバー、ダイコーター、リバースロールコーター、ロールコーター、グラビアコーター、ナイフコーター等が挙げられる。 Examples of the means for applying the coating liquid to the support include a Meyer bar, a die coater, a reverse roll coater, a roll coater, a gravure coater, a knife coater and the like.

塗工層の固化は、塗工層を形成した支持体を凝固液に浸漬し、塗工層において相分離を誘発しつつ樹脂を固化させることで行われる。これにより、支持体上に絶縁層が配置された複合体を得る。 The solidification of the coating layer is performed by immersing the support on which the coating layer is formed in the coagulating liquid and solidifying the resin while inducing phase separation in the coating layer. As a result, a complex in which an insulating layer is arranged on the support is obtained.

凝固液は、塗工液の調製に用いた良溶媒及び相分離剤と、水とを含むことが一般的である。良溶媒と相分離剤の混合比は、塗工液の調製に用いた混合溶媒の混合比に合わせるのが生産上好ましい。凝固液中の水の含有量は40質量%~90質量%であることが、絶縁層の多孔構造の形成及び生産性の観点から好ましい。凝固液の温度は、例えば20℃~50℃である。 The coagulation liquid generally contains a good solvent and a phase separation agent used for preparing the coating liquid, and water. It is preferable in terms of production that the mixing ratio of the good solvent and the phase separation agent is adjusted to the mixing ratio of the mixed solvent used for preparing the coating liquid. The content of water in the coagulation liquid is preferably 40% by mass to 90% by mass from the viewpoint of forming the porous structure of the insulating layer and productivity. The temperature of the coagulant is, for example, 20 ° C to 50 ° C.

凝固液中で塗工層を固化させた後、複合体を凝固液から引き揚げ、水洗する。水洗することによって、複合体から凝固液を除去する。さらに、乾燥することによって、複合体から水を除去する。水洗は、例えば、複合体を水浴中を搬送することによって行う。乾燥は、例えば、複合体を高温環境中を搬送すること、複合体に風をあてること、複合体をヒートロールに接触させること等によって行う。乾燥温度は40℃~80℃が好ましい。絶縁層中の水を電解液と接触させないために、絶縁層から水をできる限り除去する観点から、高温下(例えば80℃~110℃)の減圧乾燥を行うことが好ましい。 After the coating layer is solidified in the coagulation liquid, the complex is withdrawn from the coagulation liquid and washed with water. The coagulant is removed from the complex by washing with water. In addition, drying removes water from the complex. Water washing is performed, for example, by transporting the complex in a water bath. Drying is performed, for example, by transporting the complex in a high temperature environment, blowing air on the complex, bringing the complex into contact with a heat roll, and the like. The drying temperature is preferably 40 ° C to 80 ° C. In order to prevent the water in the insulating layer from coming into contact with the electrolytic solution, it is preferable to perform vacuum drying at a high temperature (for example, 80 ° C. to 110 ° C.) from the viewpoint of removing water from the insulating layer as much as possible.

絶縁層は、乾式塗工法でも形成し得る。乾式塗工法の実施形態例として、塗工液を支持体に塗工し、塗工層を乾燥させて溶媒を揮発除去することにより、絶縁層を支持体上に形成する形態が挙げられる。 The insulating layer can also be formed by a dry coating method. As an example of the embodiment of the dry coating method, there is a mode in which an insulating layer is formed on the support by applying a coating liquid to the support and drying the coating layer to volatilize and remove the solvent.

-工程B-
工程Bの実施形態例として、正極と、負極活物質層上に絶縁層を形成した負極とを重ねる実施形態;負極と、正極活物質層上に絶縁層を形成した正極とを重ねる実施形態;正極と、剥離シートから剥離した絶縁層と、負極とを重ねる実施形態;などが挙げられる。
-Process B-
As an example of the embodiment of step B, an embodiment in which a positive electrode and a negative electrode having an insulating layer formed on a negative electrode active material layer are overlapped; an embodiment in which a negative electrode and a positive electrode having an insulating layer formed on a positive electrode active material layer are overlapped; Examples thereof include an embodiment in which a positive electrode, an insulating layer peeled from a release sheet, and a negative electrode are overlapped with each other.

正極と負極との間に絶縁層を配置する方式は、正極、絶縁層、負極をこの順に少なくとも1層ずつ積層する方式(所謂スタック方式)でもよく、正極、絶縁層、負極、絶縁層をこの順に重ね、長さ方向に捲回する方式でもよい。 The method of arranging the insulating layer between the positive electrode and the negative electrode may be a method of stacking at least one layer of the positive electrode, the insulating layer, and the negative electrode in this order (so-called stack method), and the positive electrode, the insulating layer, the negative electrode, and the insulating layer are laminated in this order. A method of stacking them in order and winding them in the length direction may also be used.

-工程C-
ウェットヒートプレスとは、絶縁層に電解液を含浸させて熱プレス処理を行うことを意味し、ドライヒートプレスとは、塗工層に電解液を含浸させずに熱プレス処理を行うことを意味する。
-Process C-
Wet heat press means that the insulating layer is impregnated with the electrolytic solution and the hot press treatment is performed, and dry heat press means that the coating layer is not impregnated with the electrolytic solution and the hot press treatment is performed. do.

工程Cの実施形態例として、下記の(1)~(3)が挙げられる。 Examples of the embodiment of the step C include the following (1) to (3).

(1)積層体を外装材(例えばアルミニウムラミネートフィルム製パック。以下同じ)に収容し、そこに電解液を注入し、外装材内を真空状態にした後、外装材の上から積層体をウェットヒートプレスし、電極と絶縁層との接着と、外装材の封止とを行う。 (1) The laminate is housed in an exterior material (for example, a pack made of an aluminum laminate film; the same applies hereinafter), an electrolytic solution is injected therein, the inside of the exterior material is evacuated, and then the laminate is wetted from above the exterior material. Heat press to bond the electrode to the insulating layer and seal the exterior material.

(2)積層体をドライヒートプレスして電極と絶縁層とを接着した後、外装材に収容し、そこに電解液を注入し、外装材内を真空状態にした後、外装材の封止を行う。 (2) After dry heat pressing the laminate to bond the electrode and the insulating layer, the laminate is housed in the exterior material, an electrolytic solution is injected therein, the inside of the exterior material is evacuated, and then the exterior material is sealed. I do.

(3)積層体をドライヒートプレスして電極と絶縁層とを接着した後、外装材に収容し、そこに電解液を注入し、外装材内を真空状態にした後、外装材の上からさらに積層体をウェットヒートプレスし、電極と絶縁層との接着と、外装材の封止とを行う。 (3) After the laminate is dry heat pressed to bond the electrode and the insulating layer, the laminate is housed in the exterior material, an electrolytic solution is injected therein, the inside of the exterior material is evacuated, and then from above the exterior material. Further, the laminate is wet heat-pressed to bond the electrode and the insulating layer and to seal the exterior material.

上記(1)~(3)の製造方法における熱プレスの条件としては、ドライヒートプレス及びウェットヒートプレスそれぞれ、プレス圧は0.1MPa~10.0MPaが好ましく、温度は60℃~100℃が好ましい。 As the conditions for the hot press in the manufacturing methods (1) to (3) above, the press pressure is preferably 0.1 MPa to 10.0 MPa, and the temperature is preferably 60 ° C. to 100 ° C., respectively, for the dry heat press and the wet heat press. ..

以下に実施例を挙げて、本開示の非水系二次電池をさらに具体的に説明する。以下の実施例に示す材料、使用量、割合、処理手順等は、本開示の趣旨を逸脱しない限り適宜変更することができる。したがって、本開示の非水系二次電池の範囲は、以下に示す具体例により限定的に解釈されるべきではない。 Hereinafter, the non-aqueous secondary battery of the present disclosure will be described in more detail with reference to examples. The materials, amounts, ratios, treatment procedures, etc. shown in the following examples may be appropriately changed as long as they do not deviate from the gist of the present disclosure. Therefore, the scope of the non-aqueous secondary batteries of the present disclosure should not be construed as limiting by the specific examples shown below.

<測定方法、評価方法>
実施例及び比較例に適用した測定方法及び評価方法は、以下のとおりである。
<Measurement method, evaluation method>
The measurement methods and evaluation methods applied to the examples and comparative examples are as follows.

[絶縁層の厚さ]
電極の厚さ(μm)と、電極上に絶縁層が配置された複合体の厚さ(μm)とは、接触式の厚み計(株式会社ミツトヨ、LITEMATIC VL-50)にて5cm×3cmの長方形の中の20点を測定し、これを平均することで求めた。測定端子は直径5mmの円柱状の端子を用い、測定中に0.01Nの荷重が印加されるように調整した。そして、複合体の厚さから電極の厚さを減算した値を絶縁層の厚さ(μm)とした。
[Thickness of insulating layer]
The thickness of the electrode (μm) and the thickness of the composite in which the insulating layer is arranged on the electrode (μm) are 5 cm × 3 cm with a contact type thickness gauge (Mitutoyo Co., Ltd., LITEMATTIC VL-50). It was calculated by measuring 20 points in the rectangle and averaging them. As the measurement terminal, a columnar terminal having a diameter of 5 mm was used, and the load was adjusted so that a load of 0.01 N was applied during the measurement. Then, the value obtained by subtracting the thickness of the electrode from the thickness of the composite was taken as the thickness of the insulating layer (μm).

[絶縁層の単位面積当たりの質量]
電極と、電極上に絶縁層が配置された複合体とを、それぞれ5cm×3cmの長方形に切り出し、質量(g)をそれぞれ測定し、その質量を面積(0.0015m)で除算して単位面積当たりの質量(g/m)を求めた。そして、複合体の単位面積当たりの質量から電極の単位面積当たりの質量を減算した値を、絶縁層の単位面積当たりの質量(g/m)とした。
[Mass per unit area of insulating layer]
The electrode and the composite in which the insulating layer is arranged on the electrode are cut into rectangles of 5 cm × 3 cm each, the mass (g) is measured, and the mass is divided by the area (0.0015 m 2 ) to unit. The mass per area (g / m 2 ) was determined. Then, the value obtained by subtracting the mass per unit area of the electrode from the mass per unit area of the composite was taken as the mass per unit area (g / m 2 ) of the insulating layer.

[絶縁層の空孔率]
先述の方法で絶縁層の空孔率ε(%)を求めた。
[Porosity of insulating layer]
The porosity ε (%) of the insulating layer was determined by the method described above.

[無機粒子の平均一次粒径]
無機粒子の平均一次粒径は、絶縁層を形成するための塗工液に添加する前の無機粒子を試料とし、走査型電子顕微鏡(SEM)による観察において無作為に選んだ一次粒子100個の長径を計測し、100個の長径を平均することで求めた。
[Average primary particle size of inorganic particles]
The average primary particle size of the inorganic particles is 100 primary particles randomly selected for observation with a scanning electron microscope (SEM) using the inorganic particles before addition to the coating liquid for forming the insulating layer as a sample. It was obtained by measuring the major axis and averaging 100 major diameters.

[ポリフッ化ビニリデン系樹脂の重量平均分子量]
ポリフッ化ビニリデン系樹脂の重量平均分子量(Mw)は、ゲルパーミエーションクロマトグラフィー(Gel Permeation Chromatography、GPC)により測定した。GPCによる分子量測定は、日本分光社製のGPC装置GPC-900を用い、カラムに東ソー社製TSKgel SUPER AWM-Hを2本用い、溶媒にN,N-ジメチルホルムアミドを使用し、温度40℃、流量0.6mL/分の条件で測定し、ポリスチレン換算の分子量を得た。
[Weight average molecular weight of polyvinylidene fluoride resin]
The weight average molecular weight (Mw) of the polyvinylidene fluoride-based resin was measured by gel permeation chromatography (GPC). For molecular weight measurement by GPC, a GPC device GPC-900 manufactured by JASCO Corporation was used, two TSKgel SUPER AWM-H manufactured by Tosoh Corporation were used for the column, N, N-dimethylformamide was used as a solvent, and the temperature was 40 ° C. Measurement was performed under the condition of a flow rate of 0.6 mL / min to obtain a polystyrene-equivalent molecular weight.

[放電特性]
電池に、下記(a)の充放電を5サイクル行った後、下記(b)の充放電を1サイクル行った。
(a)4mA/4.2Vで15時間の定電流定電圧充電、及び、4mA/2.5Vカットオフで定電流放電
(b)8mA/4.2Vで8時間の定電流定電圧充電、及び、200mA/2.5Vカットオフで定電流放電
上記(b)の放電容量を上記(a)の5サイクル目の放電容量で除算し、得られた値を電池の放電特性とした。参考例1の放電特性を基準値とし、実施例及び比較例の放電特性それぞれについて参考例1に対する百分率を算出し、下記のとおり分類した。
A:95%以上
B:85%以上95%未満
C:70%以上85%未満
D:70%未満
[Discharge characteristics]
The battery was charged / discharged in the following (a) for 5 cycles, and then charged / discharged in the following (b) for 1 cycle.
(A) Constant current constant voltage charging at 4mA / 4.2V for 15 hours, constant current discharge at 4mA / 2.5V cutoff (b) Constant current constant voltage charging at 8mA / 4.2V for 8 hours, and , Constant current discharge with 200mA / 2.5V cutoff The discharge capacity of the above (b) was divided by the discharge capacity of the fifth cycle of the above (a), and the obtained value was taken as the discharge characteristic of the battery. Using the discharge characteristics of Reference Example 1 as a reference value, the percentages of the discharge characteristics of Examples and Comparative Examples with respect to Reference Example 1 were calculated and classified as follows.
A: 95% or more B: 85% or more and less than 95% C: 70% or more and less than 85% D: less than 70%

[クーロン効率]
上記(a)の1サイクル目の放電容量を充電容量で除算し、得られた値を電池のクーロン効率とした。参考例1のクーロン効率を基準値とし、実施例及び比較例のクーロン効率それぞれについて参考例1に対する百分率を算出し、下記のとおり分類した。
A:95%以上
B:85%以上95%未満
C:70%以上85%未満
D:70%未満
[Coulomb efficiency]
The discharge capacity in the first cycle of (a) above was divided by the charge capacity, and the obtained value was taken as the coulombic efficiency of the battery. Using the Coulomb efficiency of Reference Example 1 as a reference value, the percentages of the Coulomb efficiencies of Examples and Comparative Examples with respect to Reference Example 1 were calculated and classified as follows.
A: 95% or more B: 85% or more and less than 95% C: 70% or more and less than 85% D: less than 70%

[セル強度]
電池に、ISO178に準じて3点曲げ試験を行い、電池が破壊に至ったときの最大荷重(N)を求めた。参考例1の最大荷重を基準値とし、実施例及び比較例の最大荷重それぞれについて参考例1に対する百分率を算出し、下記のとおり分類した。
A:90%以上
B:90%未満
[Cell strength]
A three-point bending test was performed on the battery according to ISO178, and the maximum load (N) when the battery was destroyed was determined. Using the maximum load of Reference Example 1 as a reference value, the percentages for Reference Example 1 were calculated for each of the maximum loads of Examples and Comparative Examples, and classified as follows.
A: 90% or more B: less than 90%

<非水系二次電池の製造>
[実施例1]
-正極の作製-
コバルト酸リチウム粉末94質量部と、アセチレンブラック3質量部と、ポリフッ化ビニリデン樹脂3質量部と、適量のN-メチル-2-ピロリドンとを混練し、スラリーを作製した。スラリーを厚さ20μmのアルミニウム箔上に塗布し、乾燥後プレスし、正極(片面塗工、目付20.5mg/cm、密度2.95g/cm)を得た。
<Manufacturing of non-aqueous secondary batteries>
[Example 1]
-Preparation of positive electrode-
A slurry was prepared by kneading 94 parts by mass of lithium cobalt oxide powder, 3 parts by mass of acetylene black, 3 parts by mass of polyvinylidene fluoride resin, and an appropriate amount of N-methyl-2-pyrrolidone. The slurry was applied onto an aluminum foil having a thickness of 20 μm, dried and pressed to obtain a positive electrode (single-sided coating, basis weight 20.5 mg / cm 2 , density 2.95 g / cm 3 ).

-負極の作製-
グラファイト粉末96.2質量部と、スチレン-ブタジエン共重合体の変性体2.8質量部と、カルボキシメチルセルロース1.0質量部と、適量の水とを混練し、スラリーを作製した。スラリーを厚さ15μmの銅箔上に塗布し、乾燥後プレスし、負極(片面塗工、目付10.0mg/cm、密度1.60g/cm)を得た。
-Manufacturing of negative electrode-
A slurry was prepared by kneading 96.2 parts by mass of graphite powder, 2.8 parts by mass of a modified styrene-butadiene copolymer, 1.0 part by mass of carboxymethyl cellulose, and an appropriate amount of water. The slurry was applied onto a copper foil having a thickness of 15 μm, dried and pressed to obtain a negative electrode (single-sided coating, basis weight 10.0 mg / cm 2 , density 1.60 g / cm 3 ).

-絶縁層の作製-
VDF-HFP二元共重合体(重量平均分子量113万、全重合成分に占めるHFPの割合2.4モル%)を、濃度が5質量%となるように、ジメチルアセトアミド(DMAc)及びトリプロピレングリコール(TPG)の混合溶媒(DMAc:TPG=80:20[質量比])に溶解した後、水酸化マグネシウム粒子(平均一次粒径0.88μm)を加えて攪拌混合し、塗工液(1)を得た。VDF-HFP二元共重合体と水酸化マグネシウム粒子との質量比(VDF-HFP二元共重合体:水酸化マグネシウム粒子)が20:80であった。
-Preparation of insulating layer-
The VDF-HFP binary copolymer (weight average molecular weight 1.13 million, ratio of HFP to total polymerization components 2.4 mol%) was mixed with dimethylacetamide (DMAc) and tripropylene glycol so that the concentration was 5% by mass. After dissolving in a mixed solvent (DMAc: TPG = 80: 20 [mass ratio]) of (TPG), magnesium hydroxide particles (average primary particle size 0.88 μm) are added and mixed by stirring, and the coating liquid (1) Got The mass ratio of the VDF-HFP binary copolymer to the magnesium hydroxide particles (VDF-HFP binary copolymer: magnesium hydroxide particles) was 20:80.

ナイフコーターを用いて塗工液(1)を負極の活物質層上に塗工した。これを、凝固液(DMAc:水=50:50(質量比)、液温25℃)に5分間浸漬し塗工層を固化させ、次いで、水温25℃の水洗槽で1分間洗浄した。これを水洗槽から引き上げ、70℃の恒温槽に入れて15分間乾燥した後、110℃で3時間減圧乾燥した。こうして、負極上に絶縁層が配置された複合体を得た。 The coating liquid (1) was applied onto the active material layer of the negative electrode using a knife coater. This was immersed in a coagulating liquid (DMAc: water = 50:50 (mass ratio), liquid temperature 25 ° C.) for 5 minutes to solidify the coating layer, and then washed in a water washing tank at a water temperature of 25 ° C. for 1 minute. This was pulled up from the washing tank, placed in a constant temperature bath at 70 ° C. and dried for 15 minutes, and then dried under reduced pressure at 110 ° C. for 3 hours. In this way, a complex in which an insulating layer was arranged on the negative electrode was obtained.

-電池の作製-
正極を5.0cm×3.0cmに切り出し、負極上に絶縁層が配置された複合体を5.2cm×3.2cmに切り出して、それぞれにリードタブを溶接した。正極活物質層と絶縁層とが接するように、正極と複合体とを重ね、積層体を得た。積層体に電解液を含浸させ、アルミニウムラミネートフィルムの外装材に封入した。外装材の上から熱プレス(85℃、0.5MPa、2分間)して、電極と絶縁層との接着を行い、電池を得た。電解液には1mol/L LiPF-エチレンカーボネート:エチルメチルカーボネート(質量比3:7)を用いた。電池の設定容量は40mAh(4.2V-2.5Vの範囲)とした。
-Making batteries-
The positive electrode was cut out to 5.0 cm × 3.0 cm, and the complex having the insulating layer arranged on the negative electrode was cut out to 5.2 cm × 3.2 cm, and lead tabs were welded to each. The positive electrode and the composite were laminated so that the positive electrode active material layer and the insulating layer were in contact with each other to obtain a laminated body. The laminate was impregnated with an electrolytic solution and sealed in the exterior material of an aluminum laminate film. A battery was obtained by hot-pressing (85 ° C., 0.5 MPa, 2 minutes) from above the exterior material to bond the electrode and the insulating layer. As the electrolytic solution, 1 mol / L LiPF 6 -ethylene carbonate: ethylmethyl carbonate (mass ratio 3: 7) was used. The set capacity of the battery was 40 mAh (range 4.2 V-2.5 V).

[実施例2~8、比較例1~7]
実施例1と同様にして、但し、絶縁層の材料、組成及び厚さを表1に記載の仕様にして各電池を作製した。
実施例7~8においては、水酸化マグネシウム粒子と硫酸バリウム粒子とを、水酸化マグネシウム粒子:硫酸バリウム粒子=50:50(質量比)で併用した。
[Examples 2 to 8, Comparative Examples 1 to 7]
Each battery was manufactured in the same manner as in Example 1, except that the material, composition and thickness of the insulating layer were set to the specifications shown in Table 1.
In Examples 7 to 8, magnesium hydroxide particles and barium sulfate particles were used in combination with magnesium hydroxide particles: barium sulfate particles = 50:50 (mass ratio).

[参考例1]
-3層からなるセパレータの作製-
リバースロールコーターを用いて塗工液(1)をポリエチレン微多孔膜(厚さ7μm、空孔率36%、ガーレ値120秒/100mL)の両面に等量塗工した。これを、凝固液(DMAc:水=50:50(質量比)、液温40℃)に浸漬し塗工層を固化させ、次いで、水温40℃の水洗槽で洗浄し、乾燥した。こうして、ポリエチレン微多孔膜の両面に塗工層が形成されたセパレータを得た。
[Reference Example 1]
-Preparation of a separator consisting of 3 layers-
An equal amount of the coating liquid (1) was applied to both sides of a polyethylene microporous membrane (thickness 7 μm, porosity 36%, galley value 120 seconds / 100 mL) using a reverse roll coater. This was immersed in a coagulating liquid (DMAc: water = 50:50 (mass ratio), liquid temperature 40 ° C.) to solidify the coating layer, and then washed in a water washing tank having a water temperature of 40 ° C. and dried. In this way, a separator having a coating layer formed on both sides of the polyethylene microporous film was obtained.

-電池の作製-
実施例1における正極及び負極を用意した。正極を5.0cm×3.0cmに切り出し、負極を5.2cm×3.2cmに切り出して、それぞれにリードタブを溶接した。セパレータを5.4cm×3.4cmに切り出した。
電極活物質層とセパレータとが接するように、正極、セパレータ、負極の順に重ね、積層体を得た。積層体に電解液(実施例1で使用したものと同じ電解液である。)を含浸させ、アルミニウムラミネートフィルムの外装材に封入した。外装材の上から熱プレス(85℃、0.5MPa、2分間)して、電極とセパレータとの接着を行い、電池を得た。
-Making batteries-
The positive electrode and the negative electrode in Example 1 were prepared. The positive electrode was cut out to 5.0 cm × 3.0 cm, the negative electrode was cut out to 5.2 cm × 3.2 cm, and lead tabs were welded to each. The separator was cut out to a size of 5.4 cm × 3.4 cm.
A laminated body was obtained by stacking the positive electrode, the separator, and the negative electrode in this order so that the electrode active material layer and the separator were in contact with each other. The laminate was impregnated with an electrolytic solution (the same electrolytic solution used in Example 1) and sealed in the exterior material of the aluminum laminate film. A battery was obtained by hot-pressing (85 ° C., 0.5 MPa, 2 minutes) from above the exterior material to bond the electrode and the separator.

実施例1~8、比較例1~7及び参考例1の各電池の組成、物性及び評価結果を表1に示す。 Table 1 shows the composition, physical characteristics, and evaluation results of the batteries of Examples 1 to 8, Comparative Examples 1 to 7, and Reference Example 1.

Figure 2022024868000002
Figure 2022024868000002

100 非水系二次電池
10 電池素子
20 正極
22 正極集電体
24 正極活物質層
30 絶縁層
40 負極
42 負極集電体
44 負極活物質層
50 電解液
90 外装材
100 Non-aqueous secondary battery 10 Battery element 20 Positive electrode 22 Positive electrode current collector 24 Positive electrode active material layer 30 Insulation layer 40 Negative electrode 42 Negative electrode current collector 44 Negative electrode active material layer 50 Electrolyte 90 Exterior material

Claims (7)

正極と、
負極と、
一方の面が前記正極に接し他方の面が前記負極に接する単一層であり、ポリフッ化ビニリデン系樹脂及び無機粒子を含有する絶縁層と、
電解液と、を備え、
前記絶縁層に含まれる前記ポリフッ化ビニリデン系樹脂の重量平均分子量が90万以上150万以下であり、
前記絶縁層に占める前記無機粒子の質量割合が50質量%以上90質量%未満である、
非水系二次電池。
With the positive electrode
With the negative electrode
A single layer having one surface in contact with the positive electrode and the other surface in contact with the negative electrode, and an insulating layer containing a polyvinylidene fluoride-based resin and inorganic particles.
With an electrolytic solution,
The weight average molecular weight of the polyvinylidene fluoride-based resin contained in the insulating layer is 900,000 or more and 1.5 million or less.
The mass ratio of the inorganic particles to the insulating layer is 50% by mass or more and less than 90% by mass.
Non-water-based secondary battery.
前記無機粒子が金属水酸化物粒子及び金属硫酸塩粒子からなる群から選ばれる少なくとも1種を含む、請求項1に記載の非水系二次電池。 The non-aqueous secondary battery according to claim 1, wherein the inorganic particles contain at least one selected from the group consisting of metal hydroxide particles and metal sulfate particles. 前記絶縁層に含まれる前記無機粒子の平均一次粒径が0.01μm以上1.00μm未満である、請求項1又は請求項2に記載の非水系二次電池。 The non-aqueous secondary battery according to claim 1 or 2, wherein the average primary particle size of the inorganic particles contained in the insulating layer is 0.01 μm or more and less than 1.00 μm. 前記絶縁層の厚さが5μm以上30μm以下である、請求項1~請求項3のいずれか1項に記載の非水系二次電池。 The non-aqueous secondary battery according to any one of claims 1 to 3, wherein the thickness of the insulating layer is 5 μm or more and 30 μm or less. 前記絶縁層の空孔率が40%以上80%未満である、請求項1~請求項4のいずれか1項に記載の非水系二次電池。 The non-aqueous secondary battery according to any one of claims 1 to 4, wherein the insulating layer has a porosity of 40% or more and less than 80%. 前記絶縁層の単位面積当たりの質量が4g/m以上40g/m未満である、請求項1~請求項5のいずれか1項に記載の非水系二次電池。 The non-aqueous secondary battery according to any one of claims 1 to 5, wherein the mass of the insulating layer per unit area is 4 g / m 2 or more and less than 40 g / m 2 . リチウムイオンのドープ及び脱ドープにより起電力を得る、請求項1~請求項6のいずれか1項に記載の非水系二次電池。 The non-aqueous secondary battery according to any one of claims 1 to 6, wherein an electromotive force is obtained by doping and dedoping lithium ions.
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