JP6379460B2 - Non-aqueous secondary battery electrode binder resin manufacturing method, non-aqueous secondary battery electrode binder resin composition manufacturing method, electrode slurry preparation method, non-aqueous secondary battery electrode manufacturing method, and lithium ion secondary Battery manufacturing method - Google Patents
Non-aqueous secondary battery electrode binder resin manufacturing method, non-aqueous secondary battery electrode binder resin composition manufacturing method, electrode slurry preparation method, non-aqueous secondary battery electrode manufacturing method, and lithium ion secondary Battery manufacturing method Download PDFInfo
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Description
本発明は、非水系二次電池電極用バインダ樹脂、非水系二次電池電極用バインダ樹脂組成物、電極スラリー、非水系二次電池用電極、およびリチウムイオン二次電池に関する。 The present invention is a nonaqueous secondary battery electrode binder resin, a non-aqueous secondary battery electrode binder resin composition, the electrode slurry, the non-aqueous secondary battery electrode, and a lithium ion secondary battery.
二次電池は、ノート型パソコンや携帯電話等の弱電民生用途、ハイブリッド車や電気自動車等の蓄電池として使用されている。二次電池の中では、リチウムイオン二次電池（以下、単に「電池」と記述することがある。）が多用されている。また、リチウムイオン二次電池用電極（以下、単に「電極」と記述することがある。）は、電極活物質がバインダによって集電体に保持されたものが一般的に用いられている。 Secondary batteries are used as low-consumer consumer applications such as notebook computers and mobile phones, and as storage batteries for hybrid vehicles and electric vehicles. Among secondary batteries, lithium-ion secondary batteries (hereinafter sometimes simply referred to as “batteries”) are frequently used. Further, as an electrode for a lithium ion secondary battery (hereinafter sometimes simply referred to as “electrode”), an electrode active material held on a current collector by a binder is generally used.
従来、電極のバインダ樹脂には、例えば正極用としてポリフッ化ビニリデン（以下、「ＰＶＤＦ」と記述する。）等のフッ素系樹脂が使用されている。しかし、電極を作製するに際しては、Ｎ―メチル−２−ピロリドン（以下、「ＮＭＰ」と記述する。）等の有機溶剤を用いるため、乾燥時の溶剤回収コスト、環境に対して高負荷などの問題が顕在化している。
そのため最近では、有機溶剤を水へ置き換える流れがあり、例えば負極用のバインダ樹脂としてスチレン−ブタジエンゴムラテックスが、カルボキシメチルセルロース（以下、「ＣＭＣ」と記述する。）等の増粘剤と併せ用いられている。
Conventionally, a fluorine-based resin such as polyvinylidene fluoride (hereinafter referred to as “PVDF”) is used for a positive electrode binder resin, for example. However, when producing an electrode, an organic solvent such as N-methyl-2-pyrrolidone (hereinafter referred to as “NMP”) is used. The problem has become apparent.
Therefore, recently, there is a trend to replace the organic solvent with water. For example, styrene-butadiene rubber latex is used as a binder resin for a negative electrode in combination with a thickener such as carboxymethyl cellulose (hereinafter referred to as “CMC”). ing.
しかし、電池に組み込まれる水溶性の高分子として用いられる増粘剤のＣＭＣは天然物由来なため、供給ロットにより電極の品質が安定しにくい等の問題が指摘されている。そのため、安定品質で供給可能な非天然物の水溶性高分子が望まれる。加えて、水溶性高分子には、高い電池性能を併せ持つことも要求される。 However, since CMC, a thickener used as a water-soluble polymer incorporated in a battery, is derived from a natural product, problems such as difficulty in stabilizing the quality of electrodes depending on the supply lot have been pointed out. Therefore, a non-natural water-soluble polymer that can be supplied with stable quality is desired. In addition, water-soluble polymers are also required to have high battery performance.
近年、非天然物の水溶性高分子としてポリＮ−ビニルアセトアミドを用いた電極が提案されている（特許文献１、２）。
特許文献１では、ポリＮ−ビニルアセトアミドと、エチレンオキサイド（ＥＯ）あるいはプロピレンオキサイド(ＰＯ)を電極中に共存させることで、結着性、低温から室温下での電池特性、Ｌｉイオンの伝導性に優れることを示している。
In recent years, electrodes using poly N-vinylacetamide as a non-natural water-soluble polymer have been proposed (Patent Documents 1 and 2).
In Patent Document 1, poly N-vinylacetamide and ethylene oxide (EO) or propylene oxide (PO) are allowed to coexist in the electrode, so that binding properties, battery characteristics from low temperature to room temperature, and Li ion conductivity can be obtained. It shows that it is excellent.
特許文献２では、アミド構造を繰り返し構成単位として有する重合体を二次電池電極用バインダ樹脂として用いることで、ペースト安定性、濡れ性、集電体や電極活物質との結着性、電気化学的安定性など、電池（特に非水電池）における要求性能を改善できるとしている。 In Patent Document 2, by using a polymer having an amide structure as a repeating structural unit as a binder resin for a secondary battery electrode, paste stability, wettability, binding property with a current collector or an electrode active material, electrochemical The required performance of batteries (particularly non-aqueous batteries) can be improved.
しかしながら、特許文献１の場合、ＥＯ鎖あるいはＰＯ鎖が電解液組成に類似した分子構造のため、二次電池電極用バインダ樹脂が電解液へ溶出する場合があり、電池性能へ悪影響を及ぼすことが懸念される。
また、特許文献２に記載されているアミド構造の繰り返し単位のみで構成された重合体では、特に電極スラリー中への導電助剤の分散が困難であり、導電助剤が凝集することで、電池の電池性能へ悪影響を及ぼすことが懸念される。
However, in the case of Patent Document 1, since the EO chain or PO chain has a molecular structure similar to the electrolytic solution composition, the binder resin for the secondary battery electrode may be eluted into the electrolytic solution, which may adversely affect the battery performance. Concerned.
In addition, in the polymer composed only of the repeating unit of the amide structure described in Patent Document 2, it is difficult to disperse the conductive assistant particularly in the electrode slurry. There is concern that it will adversely affect battery performance.
本発明は上記事情を鑑みてなされたものであり、電極スラリー中への導電助剤の凝集が抑制されることで分散性が向上し、電池性能が優れた電池が得られる水溶性の二次電池電極用バインダ樹脂、二次電池電極用バインダ樹脂組成物、電極スラリー、二次電池用電極、およびリチウムイオン二次電池を提供することを目的とする。 The present invention has been made in view of the above circumstances, and is a water-soluble secondary that can improve the dispersibility by suppressing the aggregation of the conductive additive in the electrode slurry and obtain a battery with excellent battery performance. It aims at providing the binder resin for battery electrodes, the binder resin composition for secondary battery electrodes, an electrode slurry, the electrode for secondary batteries, and a lithium ion secondary battery.
本発明者らは鋭意検討した結果、二次電池電極用バインダ樹脂としてアミド構造を有する繰り返し構成単位と金属塩を形成している酸性基を持つ構成単位とを有し、前記金属塩を形成する金属イオンが周期表における１族、２族、１１族、１２族における３周期目以降に含まれるいずれかであることにより、電極スラリー中への導電助剤の凝集が抑制されることで電極スラリー中への導電助剤の分散性が向上し、電池性能が優れた電池が得られることを見出し、本発明を完成するに至った。
すなわち、本発明は以下の態様を有する。
［１］
下記一般式（１）で表される構成単位（ａ）と、金属塩を形成している酸性基を有する構成単位（ｂ）とを有した重合体であって、前記金属塩を形成する金属イオンが周期表の１族、２族、１１族、１２族における３周期目以降に含まれるいずれかであることを特徴とする二次電池電極用バインダ樹脂。
As a result of intensive studies, the inventors of the present invention have a repeating structural unit having an amide structure as a binder resin for a secondary battery electrode and a structural unit having an acidic group forming a metal salt to form the metal salt. Electrode slurry in which aggregation of conductive auxiliary agent in electrode slurry is suppressed when metal ions are included in the third and subsequent groups in Groups 1, 2, 11, and 12 of the periodic table. It has been found that a battery having excellent battery performance can be obtained by improving the dispersibility of the conductive auxiliary agent therein, and the present invention has been completed.
That is, this invention has the following aspects.
[1]
A polymer having a structural unit (a) represented by the following general formula (1) and a structural unit (b) having an acidic group forming a metal salt, the metal forming the metal salt A binder resin for a secondary battery electrode, characterized in that the ions are any one included in the third and subsequent periods of Groups 1, 2, 11, and 12 of the periodic table.
［２］
前記金属イオンがナトリウム、カリウムいずれかのイオンであることを特徴とする［１］に記載の二次電池電極用バインダ樹脂。
［３］
前記構成単位（ｂ）の酸性基がカルボン酸基、スルホン酸基、リン酸基のいずれかであることを特徴とする［１］または［２］に記載の二次電池電極用バインダ樹脂。
［４］
［１］〜［３］のいずれか一項に記載のバインダ樹脂を含む、二次電池電極用バインダ樹脂組成物。
［５］
［１］〜［３］のいずれか一項に記載の二次電池電極用バインダ樹脂、あるいは請求項４に記載の二次電池電極用バインダ樹脂組成物と、活物質と、溶媒とを含む、電極スラリー。
［６］
集電体と、該集電体上に設けられた合剤層とを備え、前記合剤層は、［１］〜［３］のいずれか一項に記載の二次電池電極用バインダ樹脂、あるいは［４］に記載の二次電池電極用バインダ樹脂組成物を含有する、二次電池用電極。
［７］
［６］に記載の二次電池用電極を備える、リチウムイオン二次電池。
[2]
The binder resin for a secondary battery electrode according to [1], wherein the metal ion is an ion of either sodium or potassium.
[3]
The binder resin for secondary battery electrodes according to [1] or [2], wherein the acidic group of the structural unit (b) is any one of a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group.
[4]
The binder resin composition for secondary battery electrodes containing the binder resin as described in any one of [1]-[3].
[5]
The binder resin for secondary battery electrodes according to any one of [1] to [3], or the binder resin composition for secondary battery electrodes according to claim 4, an active material, and a solvent. Electrode slurry.
[6]
A binder resin for a secondary battery electrode according to any one of [1] to [3], comprising a current collector and a mixture layer provided on the current collector; Or the electrode for secondary batteries containing the binder resin composition for secondary battery electrodes as described in [4].
[7]
A lithium ion secondary battery comprising the secondary battery electrode according to [6].
本発明によれば、電極スラリー中への導電助剤の凝集が抑制されることで電極スラリー中への導電助剤の分散性が向上し、電池性能が優れた電池が得られる二次電池電極用バインダ樹脂、二次電池電極用バインダ樹脂組成物、電極スラリー、二次電池用電極、およびリチウムイオン二次電池を提供できる。 ADVANTAGE OF THE INVENTION According to this invention, the secondary battery electrode from which the dispersibility of the conductive support agent in an electrode slurry improves by suppressing aggregation of the conductive support agent in an electrode slurry, and the battery excellent in battery performance is obtained. Binder resin, binder resin composition for secondary battery electrode, electrode slurry, electrode for secondary battery, and lithium ion secondary battery can be provided.
以下、本発明を詳細に説明する。
なお、本発明において「水溶性」とは、二次電池電極用バインダ樹脂が水に溶解することを意味し、具体的には、二次電池電極用バインダ樹脂の全てが水に溶解することはもちろんのこと、一部が水に溶解する場合でも、水溶性とみなす。
また、本明細書において「（メタ）アクリル」とは、アクリルとメタクリルの総称であり、「（メタ）アクリレート」とは、アクリレートとメタクリレートの総称であり、「（メタ）アリル」は、アリルとメタリルの総称である。
Hereinafter, the present invention will be described in detail.
In the present invention, “water-soluble” means that the binder resin for secondary battery electrodes dissolves in water, and specifically, that the binder resin for secondary battery electrodes dissolves in water. Of course, even if a part of it is dissolved in water, it is considered water-soluble.
In the present specification, “(meth) acryl” is a general term for acrylic and methacrylic, “(meth) acrylate” is a general term for acrylate and methacrylate, and “(meth) allyl” means allyl and Generic name for methallyl.
［二次電池電極用バインダ樹脂］
本発明の二次電池電極用バインダ樹脂（以下、単に「バインダ樹脂組成物」ということもある。）は、下記一般式（１）で表される構成単位（ａ）と、金属塩を形成している酸性基を有する構成単位（ｂ）とを有した重合体であって、前記金属塩を形成する金属イオンが周期表の１族、２族、１１族、１２族における３周期目以降に含まれるいずれかである。
[Binder resin for secondary battery electrode]
The binder resin for secondary battery electrodes of the present invention (hereinafter sometimes simply referred to as “binder resin composition”) forms a metal salt with the structural unit (a) represented by the following general formula (1). And a structural unit (b) having an acidic group, wherein the metal ions forming the metal salt are present in the third and subsequent periods of Groups 1, 2, 11, and 12 of the periodic table. Any one included.
＜構成単位（ａ）＞
本発明における二次電池電極用バインダ樹脂は、下記一般式（１）で表される構成単位（ａ）を含む重合体である。
<Structural unit (a)>
The binder resin for secondary battery electrodes in the present invention is a polymer containing a structural unit (a) represented by the following general formula (1).
前記一般式（１）で表されるアミド構造を繰り返し構成単位とすることで、電解液への膨潤性に優れ、電池内で優れた安定性を発揮するバインダ樹脂とすることが可能になる。
また、樹脂の水溶性を高める観点から、Ｒ１は炭素数が少ないほうが好ましく、水素原子または炭素数１〜３の炭化水素基がより好ましく、さらに水素原子であることが好ましい。Ｒ２は樹脂の水溶性を高める観点から、水素原子または炭素数が少ない炭化水素であるほうが好ましく、水素原子または炭素数１〜３の炭化水素基がより好ましく、水素原子または炭素数１の炭化水素基がさらに好ましい。
前記一般式（１）で表される構成単位の由来となる単量体としては、Ｎ−ビニルホルムアミド、Ｎ−ビニルアセトアミドなどが挙げられる。
By using the amide structure represented by the general formula (1) as a repeating unit, it is possible to obtain a binder resin that is excellent in swellability to an electrolytic solution and exhibits excellent stability in the battery.
From the viewpoint of increasing the water solubility of the resin, R 1 preferably has a smaller number of carbon atoms, more preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, and further preferably a hydrogen atom. From the viewpoint of enhancing the water solubility of the resin, R 2 is preferably a hydrogen atom or a hydrocarbon having a small number of carbon atoms, more preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, and a hydrogen atom or a carbon atom having 1 carbon atom. A hydrogen group is more preferable.
Examples of the monomer derived from the structural unit represented by the general formula (1) include N-vinylformamide and N-vinylacetamide.
バインダ樹脂のうち、一般式（１）で表される構成単位（ａ）が含まれる割合は１〜９９質量％であることが好ましく、３〜９７質量％であることがより好ましく、５〜９５質量％であることが特に好ましい。
一般式（１）で表される構成単位（ａ）が含まれる割合を５質量％以上とすることで電解液に対するバインダ樹脂の安定性を向上させることが可能となり、電池性能に優れた電池が得られる。
In the binder resin, the proportion of the structural unit (a) represented by the general formula (1) is preferably 1 to 99% by mass, more preferably 3 to 97% by mass, and more preferably 5 to 95%. It is particularly preferable that the content is% by mass.
By making the proportion of the structural unit (a) represented by the general formula (1) 5% by mass or more, it becomes possible to improve the stability of the binder resin with respect to the electrolytic solution, and a battery having excellent battery performance is obtained. can get.
＜構成単位（ｂ）＞
本発明の二次電池電極用バインダ樹脂を構成する構成単位のうち、構成単位（ｂ）は、金属塩を形成している酸性基を有する。酸性基としては、例えば、カルボン酸基、スルホン酸基、リン酸基を用いることが好ましい。
<Structural unit (b)>
Among the structural units constituting the binder resin for a secondary battery electrode of the present invention, the structural unit (b) has an acidic group forming a metal salt. As the acidic group, for example, a carboxylic acid group, a sulfonic acid group, or a phosphoric acid group is preferably used.
酸性基を持つ構成単位となる単量体の例としては、一般式（１）で表される単量体と共重合可能であれば特に限定されないが、具体的には、（メタ）アクリル酸、クロトン酸、マレイン酸、フマル酸、イタコン酸、シトラコン酸、メサコン酸、けい皮酸等の脂肪族不飽和カルボン酸；（メタ）アクリル酸２−カルボキシエチル、クロトン酸２−カルボキシエチル、マレイン酸モノメチル、イタコン酸モノオクチル等のカルボキシル基含有不飽和カルボン酸エステル；２−カルボキシプロピオン酸ビニル等のカルボキシル基含有不飽和単量体；（メタ）アリルスルホン酸、（メタ）アリルオキシベンゼンスルホン酸、スチレンスルホン酸、２−アクリルアミド−２−メチルプロパンスルホン酸等のスルホン酸基含有不飽和単量体；（メタ）アクリル酸−２−リン酸エチル、３−アリロキシ−２−ヒドロキシプロパンリン酸、プロトポルフィリンジメチルエステル等のリン酸基含有不飽和単量体等の酸基含有不飽和単量体；及びこれらの混合物を挙げることができる。 An example of the monomer serving as a structural unit having an acidic group is not particularly limited as long as it is copolymerizable with the monomer represented by the general formula (1). Specifically, (meth) acrylic acid , Crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, cinnamic acid and other aliphatic unsaturated carboxylic acids; (meth) acrylic acid 2-carboxyethyl, crotonic acid 2-carboxyethyl, maleic acid Carboxyl group-containing unsaturated carboxylic acid esters such as monomethyl and monooctyl itaconate; carboxyl group-containing unsaturated monomers such as vinyl 2-carboxypropionate; (meth) allylsulfonic acid, (meth) allyloxybenzenesulfonic acid, Sulphonic acid group-containing unsaturated monomers such as styrene sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid; Acid group-containing unsaturated monomers such as phosphoric acid group-containing unsaturated monomers such as ethyl 2-phosphate, 3-allyloxy-2-hydroxypropane phosphate, and protoporphyrin dimethyl ester; and mixtures thereof Can be mentioned.
また、構成単位（ｂ）の金属塩を形成している金属イオンは、周期表における１族、２族、１１族、１２族における３周期目以降に含まれるいずれかとすることで、導電助剤の分散性を向上させることができ、電池性能の優れた電池を作製することが可能となる。
金属イオンとしては、１族：ナトリウム、カリウム、ルビジウム、セシウム、フランシウム、２族：マグネシウム、カルシウム、ストロンチウム、バリウム、ラジウム、１１族：銅、銀、金、１２族：亜鉛、カドミウム、水銀が挙げられ、前記金属イオンをナトリウム、カリウムのいずれかとすると、電極スラリー中への導電助剤の分散性を更に良好に出来る。
Moreover, the metal ion which forms the metal salt of the structural unit (b) is included in any of the third and subsequent periods in the first, second, eleventh and twelfth groups in the periodic table. Thus, it becomes possible to produce a battery having excellent battery performance.
Examples of metal ions include Group 1: sodium, potassium, rubidium, cesium, francium, Group 2: magnesium, calcium, strontium, barium, radium, Group 11: copper, silver, gold, Group 12: zinc, cadmium, and mercury. When the metal ion is either sodium or potassium, the dispersibility of the conductive additive in the electrode slurry can be further improved.
また、構成単位（ｂ）を含む割合は１〜９９質量％であることが好ましく、３〜９７質量％であることがより好ましく、５〜９５質量％であることが特に好ましい。構成単位（ｂ）の割合を５質量％以上とすることで、電極スラリー中での導電助剤の分散性を良好とすることができ、電池性能に優れた電池を作製することが可能となる。 Moreover, it is preferable that the ratio containing a structural unit (b) is 1-99 mass%, It is more preferable that it is 3-97 mass%, It is especially preferable that it is 5-95 mass%. By setting the proportion of the structural unit (b) to 5% by mass or more, the dispersibility of the conductive additive in the electrode slurry can be improved, and a battery excellent in battery performance can be manufactured. .
また、構成単位（ｂ）中の酸性基のうち、金属イオンと金属塩を形成しているものの割合は特に制限されるものではないが、塩基性成分として、周期表における１族、２族、１１族、１２族における３周期目以降に含まれるいずれかの金属イオンで構成される無機塩を、構成単位（ｂ）中の酸性基との中和反応に用いた場合、構成単位（ｂ）中の酸性基に対して１〜１００ｍｏｌ％の無機塩を用いることが好ましく、５〜１００ｍｏｌ％が更に好ましく、１０〜１００ｍｏｌ％が特に好ましい。上記範囲で無機塩を使用することで、酸性基と周期表における１族、２族、１１族、１２族における３周期目以降に含まれるいずれかの金属イオンで金属塩が形成される。これにより、電極スラリー中での導電助剤の分散性を良好にすることでき、電池性能に優れた電極を作製することが可能になる。 Further, the proportion of the acidic group in the structural unit (b) that forms a metal salt with a metal ion is not particularly limited, but as a basic component, the first group, the second group in the periodic table, In the case where an inorganic salt composed of any metal ion included in the third and subsequent groups in Group 11 and Group 12 is used for a neutralization reaction with an acidic group in the structural unit (b), the structural unit (b) It is preferable to use 1 to 100 mol% of an inorganic salt, more preferably 5 to 100 mol%, and particularly preferably 10 to 100 mol% with respect to the acidic group therein. By using an inorganic salt in the above range, a metal salt is formed with an acidic group and any metal ion included in the third and subsequent periods of Groups 1, 2, 11, and 12 in the periodic table. Thereby, the dispersibility of the conductive support agent in an electrode slurry can be made favorable, and it becomes possible to produce the electrode excellent in battery performance.
バインダ樹脂の質量平均分子量は５０００〜１０００万であることが好ましく、１００００〜７５０万であることがより好ましい。バインダ樹脂の質量平均分子量が上記下限値以上であると電解液中におけるバインダ樹脂の溶出、膨潤に対する安定性がより高まり、上記上限値以下であると水溶性がより良好となる。
バインダ樹脂の質量平均分子量は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）を用いて測定することができる。例えば、テトラヒドロフランや水等の溶媒を溶離液とし、ポリスチレン換算分子量として求めることができる。
また、バインダ樹脂を水に溶解して得られる水溶液の粘度から、粘度換算分子量を測定することができる。
The mass average molecular weight of the binder resin is preferably 5,000 to 10,000,000, and more preferably 10,000 to 7.5 million. When the weight average molecular weight of the binder resin is equal to or higher than the lower limit, the binder resin is more stably eluted and swelled in the electrolytic solution, and when the weight average molecular weight is equal to or lower than the upper limit, the water solubility is improved.
The mass average molecular weight of the binder resin can be measured using gel permeation chromatography (GPC). For example, it can be determined as a molecular weight in terms of polystyrene using a solvent such as tetrahydrofuran or water as an eluent.
Moreover, a viscosity conversion molecular weight can be measured from the viscosity of the aqueous solution obtained by melt | dissolving binder resin in water.
バインダ樹脂の重合の方法は特に限定されず、使用する単量体の種類や生成する重合体の溶解性などに応じて、溶液重合、懸濁重合、乳化重合などを選ぶことができる。
例えば、使用する単量体が水に可溶であり、かつ生成する重合体も水に対して十分な親和性を有する場合には、水溶液重合を用いることができる。水溶液重合は、原料となる単量体および水溶性重合開始剤を水に溶解し、加熱することにより重合体を得る方法である。
The method for polymerizing the binder resin is not particularly limited, and solution polymerization, suspension polymerization, emulsion polymerization, and the like can be selected according to the type of monomer used and the solubility of the polymer to be formed.
For example, aqueous solution polymerization can be used when the monomer used is soluble in water and the polymer produced also has sufficient affinity for water. Aqueous polymerization is a method in which a monomer and a water-soluble polymerization initiator as raw materials are dissolved in water and heated to obtain a polymer.
また、使用する単量体の水への溶解度が小さいときは、懸濁重合、乳化重合などを用いることができる。乳化重合は、水中に原料となる単量体、乳化剤、水溶性重合開始剤などを加え、撹拌下に加熱することにより重合体を得る方法である。
また、得られるバインダ樹脂の分子量を調整するために、重合前の単量体溶液中に連鎖移動剤を添加して重合を行っても良い。用いる連鎖移動剤は、単量体や溶剤に可溶のものであれば、その種類を問わない。
重合後は、ろ過、遠心分離、加熱乾燥、減圧乾燥及びこれらを組み合わせて水を除去することで、重合体が得られる。
バインダ樹脂の形態としては、粉末状、顆粒状、水等の溶媒に溶解または分散したドープ状などが挙げられる。
Moreover, when the solubility of the monomer used in water is small, suspension polymerization, emulsion polymerization, or the like can be used. Emulsion polymerization is a method for obtaining a polymer by adding a raw material monomer, an emulsifier, a water-soluble polymerization initiator, and the like to water and heating with stirring.
Moreover, in order to adjust the molecular weight of the obtained binder resin, you may superpose | polymerize by adding a chain transfer agent in the monomer solution before superposition | polymerization. The chain transfer agent used is not limited as long as it is soluble in a monomer or a solvent.
After the polymerization, a polymer is obtained by removing water by filtration, centrifugation, heat drying, drying under reduced pressure, and a combination thereof.
Examples of the binder resin include powder, granules, and a dope dissolved or dispersed in a solvent such as water.
以上説明した本発明の二次電池電極用バインダ樹脂は水溶性であり、導電助剤の分散性に優れ、電極スラリー中への導電助剤の凝集を防止でき、電池特性に優れた電池が得られる。 The binder resin for a secondary battery electrode of the present invention described above is water-soluble, has excellent dispersibility of the conductive aid, can prevent aggregation of the conductive aid into the electrode slurry, and obtains a battery with excellent battery characteristics. It is done.
［二次電池電極用バインダ樹脂組成物］
本発明の二次電池電極用バインダ樹脂組成物（以下、単に「バインダ樹脂組成物」ということもある。）は、上述した本発明の二次電池電極用バインダ樹脂を含有する。
バインダ樹脂組成物の形態としては、粉末状、水等の溶媒に溶解または分散したドープ状などが挙げられる。
[Binder resin composition for secondary battery electrode]
The binder resin composition for secondary battery electrodes of the present invention (hereinafter sometimes simply referred to as “binder resin composition”) contains the binder resin for secondary battery electrodes of the present invention described above.
Examples of the form of the binder resin composition include a powder form and a dope form dissolved or dispersed in a solvent such as water.
バインダ樹脂組成物中のバインダ樹脂の含有量は、５０質量％以上が好ましく、８０質量％以上がより好ましく、１００質量％であってもよい。上記下限値以上であれば、本発明の効果が顕著に発揮される。 The content of the binder resin in the binder resin composition is preferably 50% by mass or more, more preferably 80% by mass or more, and may be 100% by mass. If it is more than the said lower limit, the effect of this invention will be exhibited notably.
本発明のバインダ樹脂組成物は、電池性能に影響が出ない量であれば、必要に応じて本発明のバインダ樹脂以外のバインダ樹脂（他のバインダ樹脂）や、粘度調整剤、結着性向上剤、分散剤等の公知の添加剤などを含有してもよい。 As long as the amount of the binder resin composition of the present invention does not affect the battery performance, a binder resin other than the binder resin of the present invention (other binder resin), a viscosity modifier, and an improved binding property as necessary. You may contain well-known additives, such as an agent and a dispersing agent.
他のバインダ樹脂としては、例えば酢酸ビニル共重合体、スチレン−ブタジエンブロッ
ク共重合体（ＳＢＲ）、アクリル酸変性ＳＢＲ樹脂（ＳＢＲ系ラテックス）、アクリルゴム系ラテックスや、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重含体（ＰＦＡ）、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体（ＦＥＰ）、エチレン−テトラフルオロエチレン共重合体（ＥＴＦＥ）等のフッ素系樹脂が挙げられる。
これらは１種単独で用いてもよいし、２種以上を併用してもよい。
Other binder resins include, for example, vinyl acetate copolymer, styrene-butadiene block copolymer (SBR), acrylic acid modified SBR resin (SBR latex), acrylic rubber latex, polyvinylidene fluoride (PVDF), poly Tetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), etc. A fluorine-type resin is mentioned.
These may be used alone or in combination of two or more.
粘度調整剤としては、例えばカルボキシメチルセルロース、メチルセルロース、ヒドロキシプロピルセルロース等のセルロース系重合体及びこれらのアンモニウム塩；ポリ（メタ）アクリル酸ナトリウム等のポリ（メタ）アクリル酸塩；ポリビニルアルコール、ポリエチレンオキシド、ポリビニルピロリドン、アクリル酸又はアクリル酸塩とビニルアルコールの共重合体、無水マレイン酸、マレイン酸又はフマル酸とビニルアルコールの共重合体、変性ポリビニルアルコール、変性ポリアクリル酸、ポリエチレングリコール、ポリカルボン酸が挙げられる。これらは１種単独で用いてもよいし、２種以上を併用してもよい。
粘度調整剤等の添加剤は最終的には電極に残留するので、添加剤はなるべく加えないことが望ましいが、加える場合には電気化学的安定性を有する添加剤を用いることが好ましい。
Examples of the viscosity modifier include cellulose polymers such as carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, and ammonium salts thereof; poly (meth) acrylates such as sodium poly (meth) acrylate; polyvinyl alcohol, polyethylene oxide, Polyvinylpyrrolidone, acrylic acid or acrylate and vinyl alcohol copolymer, maleic anhydride, maleic acid or fumaric acid and vinyl alcohol copolymer, modified polyvinyl alcohol, modified polyacrylic acid, polyethylene glycol, polycarboxylic acid Can be mentioned. These may be used alone or in combination of two or more.
Since additives such as a viscosity modifier eventually remain on the electrode, it is desirable not to add the additives as much as possible, but when they are added, it is preferable to use an additive having electrochemical stability.
バインダ樹脂組成物は、公知の方法により製造することができる。例えば、粉末状の本発明のバインダ樹脂と、必要に応じて粉末状の他のバインダ樹脂や添加剤とを粉体混合したり、本発明のバインダ樹脂と、必要に応じて粉末状の他のバインダ樹脂や添加剤とを水に分散したりすることで得られる。 The binder resin composition can be produced by a known method. For example, powdery binder resin of the present invention and powdery other binder resin and additives as necessary, or powdery binder resin of the present invention and other powdery powder as necessary It can be obtained by dispersing a binder resin and additives in water.
以上説明した本発明の二次電池電極用バインダ樹脂組成物は水溶性であり、電解液への膨潤性に優れている。また、導電助剤の分散性に優れた二次電池電極用バインダ樹脂となっており、この性能により、スラリー中での導電助剤の凝集を防止することができ、電池性能に優れた電池を得ることが可能となる。 The binder resin composition for a secondary battery electrode of the present invention described above is water-soluble and excellent in swellability to an electrolytic solution. In addition, it is a binder resin for secondary battery electrodes with excellent dispersibility of the conductive auxiliary agent, and this performance can prevent aggregation of the conductive auxiliary agent in the slurry, resulting in a battery with excellent battery performance. Can be obtained.
［電極スラリー］
本発明の電極スラリーは、上述の本発明の二次電池電極用バインダ樹脂あるいは二次電池電極用バインダ樹脂組成物と、活物質と、必要に応じて導電助剤などの添加剤とを溶媒に分散させ、調製される。
溶媒としては、水、水と有機溶媒との混合溶媒が挙げられる。
有機溶媒としては、バインダ樹脂やバインダ樹脂組成物を均一に溶解または分散できる溶媒であれば特に制限されないが、例えばＮＭＰ、ＮＭＰとエステル系溶媒（酢酸エチル、酢酸ｎ−ブチル、ブチルセロソルブアセテート、ブチルカルビトールアセテート等）の混合溶液、ＮＭＰとグライム系溶媒（ジグライム、トリグライム、テトラグライム等）の混合溶液が挙げられる。これら有機溶媒は、１種単独で用いてもよいし、２種以上を併用してもよい。
ただし、有機溶媒は環境への負荷が高いことから、溶媒としては水を用いるのが好ましい。
本発明のバインダ樹脂およびバインダ樹脂組成物は水溶性であるため、水に容易に溶解または分散できる。
[Electrode slurry]
The electrode slurry of the present invention uses the above-described binder resin for a secondary battery electrode or binder resin composition for a secondary battery electrode of the present invention, an active material, and, if necessary, an additive such as a conductive additive as a solvent. Dispersed and prepared.
Examples of the solvent include water and a mixed solvent of water and an organic solvent.
The organic solvent is not particularly limited as long as it can uniformly dissolve or disperse the binder resin or the binder resin composition. For example, NMP, NMP and an ester solvent (ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbyl And a mixed solution of NMP and a glyme-based solvent (diglyme, triglyme, tetraglyme, etc.). These organic solvents may be used individually by 1 type, and may use 2 or more types together.
However, since the organic solvent has a high environmental load, it is preferable to use water as the solvent.
Since the binder resin and binder resin composition of the present invention are water-soluble, they can be easily dissolved or dispersed in water.
電極スラリー中の溶媒の含有量は、常温でバインダ樹脂あるいはバインダ樹脂組成物が溶解または分散状態を保てる必要最低限の量以上であればよい。
ただし、スラリー調製工程では、通常、溶媒を加えながら電極スラリーの粘度調節を行なうため、必要以上に希釈し過ぎない任意の量とすることが好ましい。
The content of the solvent in the electrode slurry may be at least the necessary minimum amount at which the binder resin or the binder resin composition can be dissolved or dispersed at room temperature.
However, in the slurry preparation step, since the viscosity of the electrode slurry is usually adjusted while adding a solvent, it is preferable to use an arbitrary amount that is not excessively diluted.
電極スラリーに用いる活物質は、正極電極の電位と負極電極の電位が異なるものであればよい。
リチウムイオン二次電池の場合、正極電極に用いられる活物質（正極活物質）としては、例えば鉄、コバルト、ニッケル、マンガンから選ばれる少なくとも１種類以上の金属と、リチウムとを含有するリチウム含有金属複合酸化物が挙げられる。これら正極活物質は、１種単独で用いてもよいし、２種以上を併用してもよい。
一方、負極電極に用いられる活物質（負極活物質）としては、例えば黒鉛、非晶質炭素、炭素繊維、コークス、活性炭等の炭素材料；前記炭素材料とシリコン、錫、銀等の金属またはこれらの酸化物との複合物が挙げられる。これら負極活物質は、１種単独で用いてもよいし、２種以上を併用してもよい。
The active material used for the electrode slurry only needs to have a different potential between the positive electrode and the negative electrode.
In the case of a lithium ion secondary battery, as an active material (positive electrode active material) used for the positive electrode, for example, a lithium-containing metal containing at least one metal selected from iron, cobalt, nickel, and manganese and lithium A composite oxide is mentioned. These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together.
On the other hand, examples of the active material (negative electrode active material) used for the negative electrode include carbon materials such as graphite, amorphous carbon, carbon fiber, coke, and activated carbon; the carbon materials and metals such as silicon, tin, and silver; And composites with these oxides. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.
リチウムイオン二次電池においては、活物質として、正極電極にはリチウム含有金属複合酸化物、負極電極には黒鉛を用いることが好ましい。このような組合せとすることで、
リチウムイオン二次電池の電圧は約４Ｖとなる。
In the lithium ion secondary battery, it is preferable to use lithium-containing metal composite oxide for the positive electrode and graphite for the negative electrode as the active material. With such a combination,
The voltage of the lithium ion secondary battery is about 4V.
なお、電極スラリーは、導電助剤を含有してもよい。導電助剤を含有することで、電池性能をより高められる。
導電助剤としては、例えば黒鉛、カーボンブラック、アセチレンブラックなどが挙げられる。これら導電助剤は、１種単独で用いてもよいし、２種以上を併用してもよい。
The electrode slurry may contain a conductive additive. Battery performance can be further improved by containing a conductive additive.
Examples of the conductive assistant include graphite, carbon black, and acetylene black. These conductive assistants may be used alone or in combination of two or more.
［二次電池用電極］
本発明の二次電池用電極（以下、単に「電極」ということもある。）は、集電体と、該集電体上に設けられた合剤層とを備える。
合剤層は、上述した本発明のバインダ樹脂あるいはバインダ樹脂組成物を含有する層であり、例えば本発明のバインダ樹脂あるいはバインダ樹脂組成物に活物質を配合し、溶媒に溶解または分散させたスラリーを乾燥して得られる固相である。
[Secondary battery electrodes]
The electrode for a secondary battery of the present invention (hereinafter sometimes simply referred to as “electrode”) includes a current collector and a mixture layer provided on the current collector.
The mixture layer is a layer containing the binder resin or binder resin composition of the present invention described above. For example, a slurry in which an active material is blended in the binder resin or binder resin composition of the present invention and dissolved or dispersed in a solvent. Is a solid phase obtained by drying.
合剤層の厚みは、２０〜２００μｍが好ましく、３０〜１２０μｍがより好ましい。
なお、正極用の電極（正極電極）は負極用の電極（負極電極）と比べ活物質の容量が小さいため、正極電極の合剤層は、負極電極の合剤層より厚くされることが好ましい。
20-200 micrometers is preferable and, as for the thickness of a mixture layer, 30-120 micrometers is more preferable.
Since the positive electrode (positive electrode) has a smaller active material capacity than the negative electrode (negative electrode), the positive electrode mixture layer is preferably thicker than the negative electrode mixture layer.
集電体は、導電性を有する物質であればよく、材料としては金属を使用できる。具体的には、アルミニウム、銅、ニッケルなどが使用できる。
集電体の形状としては、目的とする電池の形態に応じて決定でき、例えば薄膜状、網状、繊維状が挙げられる。これらの中でも、薄膜状が好ましい。
集電体の厚みは、５〜３０μｍが好ましく、８〜２５μｍがより好ましい。
The current collector may be any material having conductivity, and a metal can be used as the material. Specifically, aluminum, copper, nickel or the like can be used.
The shape of the current collector can be determined according to the shape of the target battery, and examples thereof include a thin film shape, a net shape, and a fiber shape. Among these, a thin film is preferable.
The thickness of the current collector is preferably 5 to 30 μm, more preferably 8 to 25 μm.
本発明の電極は、公知の方法を用いて製造することができ、例えば、本発明の電極スラリーを調製し（スラリー調製工程）、該電極スラリーを集電体に塗布し（塗布工程）、次いで溶媒を除去し（溶媒除去工程）、必要に応じて圧延して（圧延工程）、集電体表面に合剤層を形成することにより製造することができる。 The electrode of the present invention can be produced using a known method. For example, the electrode slurry of the present invention is prepared (slurry preparation step), the electrode slurry is applied to a current collector (application step), and then It can manufacture by removing a solvent (solvent removal process), rolling as needed (rolling process), and forming a mixture layer on the collector surface.
塗布工程は、集電体に電極スラリーを任意の厚みで塗布できればよく、例えばコンマコーター等を用いて行なうことができる。
溶媒除去工程は、溶媒を除去できればよく、例えば温風、熱風、低湿風による乾燥、真空乾燥、（遠）赤外線や電子線等の照射による乾燥法等が挙げられる。
圧延工程は、合剤層を任意の厚みに圧延できればよく、例えば金型プレスやロールプレス等の方法が挙げられる。
なお、得られた電極を任意の寸法に切断してもよい。
The coating step is not particularly limited as long as the electrode slurry can be applied to the current collector with an arbitrary thickness. For example, a comma coater or the like can be used.
The solvent removal step is not particularly limited as long as the solvent can be removed, and examples thereof include drying with warm air, hot air, low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams.
The rolling step is not limited as long as the mixture layer can be rolled to an arbitrary thickness, and examples thereof include a mold press and a roll press.
In addition, you may cut | disconnect the obtained electrode to arbitrary dimensions.
以上説明した本発明の電極は、本発明のバインダ樹脂あるいはバインダ樹脂組成物を含む合剤層が集電体上に形成されているので、導電助剤の凝集が見られない。また、本発明のバインダ樹脂が電解液への膨潤性に優れることから電池性能に優れた電極を得ることが可能になる。以上のことから本発明の電極は、リチウムイオン二次電池用の電極として好適である。 In the electrode of the present invention described above, the mixture layer containing the binder resin or the binder resin composition of the present invention is formed on the current collector, and therefore no aggregation of the conductive assistant is observed. In addition, since the binder resin of the present invention is excellent in swellability to an electrolytic solution, an electrode excellent in battery performance can be obtained. From the above, the electrode of the present invention is suitable as an electrode for a lithium ion secondary battery.
［リチウムイオン二次電池］
本発明のリチウムイオン二次電池は、本発明の電極を備える。
リチウムイオン二次電池は、例えば、正極電極と負極電極とを、透過性のセパレータを間に介して配置し、これに非水系の電解液を含浸させた非水系二次電池；集電体の両面に合剤層が形成された負極電極／セパレータ／集電体の両面に合剤層が形成された正極電極／セパレータからなる積層体をロール状（渦巻状）に巻回した巻回体が、電解液と共に電池缶（有底の金属ケーシング）に収容された筒状の非水系二次電池などが挙げられる。
[Lithium ion secondary battery]
The lithium ion secondary battery of the present invention includes the electrode of the present invention.
A lithium ion secondary battery is, for example, a non-aqueous secondary battery in which a positive electrode and a negative electrode are disposed with a permeable separator interposed therebetween, and impregnated with a non-aqueous electrolyte solution; A wound body obtained by winding a laminate composed of a positive electrode / separator having a mixture layer formed on both sides of a negative electrode / separator / current collector having a mixture layer formed on both sides in a roll shape (spiral shape). And a cylindrical non-aqueous secondary battery housed in a battery can (a bottomed metal casing) together with the electrolyte.
電解液は、有機溶媒に電解質を溶解した溶液である。
有機溶媒としては、例えばプロピレンカーボネート、エチレンカーボネート、ブチレンカーボネート、ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネート等のカーボネート類；γ−ブチロラクトン等のラクトン類；トリメトキシメタン、１，２−ジメトキシエタン、ジエチルエーテル、２−エトキシエタン、テトラヒドロフラン、２−メチルテトラヒドロフラン等のエーテル類；ジメチルスルホキシド等のスルホキシド類；１，３−ジオキソラン、４−メチル−１，３−ジオキソラン等のオキソラン類；アセトニトリル、ニトロメタン、ＮＭＰ等の含窒素類；ギ酸メチル、酢酸メチル、酢酸ブチル、プロピオン酸メチル、プロピオン酸エチル、リン酸トリエステル等のエステル類；ジグライム、トリグライム、テトラグライム等のグライム類；アセトン、ジエチルケトン、メチルエチルケトン、メチルイソブチルケトン等のケトン類；スルホラン等のスルホン類；３−メチル−２−オキサゾリジノン等のオキサゾリジノン類；１，３−プロパンスルトン、４−ブタンスルトン、ナフタスルトン等のスルトン類などが挙げられる。
これら有機溶媒は、１種単独で用いてもよいし、２種以上を併用してもよい。
The electrolytic solution is a solution in which an electrolyte is dissolved in an organic solvent.
Examples of the organic solvent include carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; lactones such as γ-butyrolactone; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether , Ethers such as 2-ethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; acetonitrile, nitromethane, NMP and the like Nitrogens such as methyl formate, methyl acetate, butyl acetate, methyl propionate, ethyl propionate, phosphate triester; diglyme, triglyme, tetra Glymes such as lime; ketones such as acetone, diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone; sulfones such as sulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; 1,3-propane sultone, 4-butane sultone, And sultone such as naphtha sultone.
These organic solvents may be used individually by 1 type, and may use 2 or more types together.
電解質としては、例えばＬｉＣｌＯ４、ＬｉＢＦ４、ＬｉＩ、ＬｉＰＦ６、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、ＬｉＡｓＦ６、ＬｉＳｂＦ６、ＬｉＡｌＣｌ４、ＬｉＣｌ、ＬｉＢｒ、ＬｉＢ(Ｃ２Ｈ５)４、ＬｉＣＨ３ＳＯ３、ＬｉＣ４Ｆ９ＳＯ３、Ｌｉ(ＣＦ３ＳＯ２)２Ｎ、Ｌｉ[(ＣＯ２)２]２Ｂなどが挙げられる。
電解質としては、ＬｉＰＦ６を用いることが好ましく、特にリチウムイオン二次電池の電解質として好適である。
As the electrolyte, for example LiClO 4, LiBF 4, LiI, LiPF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) 4, LiCH 3 SO 3 , LiC 4 F 9 SO 3 , Li (CF 3 SO 2 ) 2 N, Li [(CO 2 ) 2 ] 2 B, and the like can be given.
LiPF 6 is preferably used as the electrolyte, and is particularly suitable as an electrolyte for a lithium ion secondary battery.
リチウムイオン二次電池は、公知の方法を用いて製造することができる。以下にリチウムイオン二次電池の製造方法の一例を説明する。
まず、正極電極と負極電極とを、例えばポリエチレン微多孔膜からなるセパレータを介してスパイラル状に捲回して捲回体とする。得られた捲回体を電池缶に挿入し、予め負極電極の集電体に溶接しておいたタブ端子を電池缶底に溶接する。
次いで、電池缶に電解液を注入し、さらに予め正極電極の集電体に溶接しておいたタブ端子を電池の蓋に溶接し、蓋を絶縁性のガスケットを介して電池缶の上部に配置し、蓋と電池缶とが接した部分をかしめて密閉して、リチウムイオン二次電池とする。
なお、本発明の電極は柔軟性に優れるので、捲回しやすい。
A lithium ion secondary battery can be manufactured using a well-known method. Below, an example of the manufacturing method of a lithium ion secondary battery is demonstrated.
First, the positive electrode and the negative electrode are wound in a spiral shape through a separator made of, for example, a polyethylene microporous film to form a wound body. The obtained wound body is inserted into a battery can, and a tab terminal previously welded to the current collector of the negative electrode is welded to the bottom of the battery can.
Next, inject the electrolyte into the battery can, weld the tab terminal that was previously welded to the current collector of the positive electrode to the battery lid, and place the lid on the top of the battery can via an insulating gasket Then, the portion where the lid and the battery can are in contact with each other is caulked and sealed to obtain a lithium ion secondary battery.
In addition, since the electrode of the present invention is excellent in flexibility, it is easy to wind.
このようにして得られる本発明のリチウムイオン二次電池は、本発明の電極を備えているので、電池性能に優れる。電池性能に優れるのは、電極スラリー中での導電助剤の分散性に優れ、導電助剤の凝集を防止出来るためである。更に、合剤層が本発明のバインダ樹脂あるいはバインダ樹脂組成物を含有することにより、バインダ樹脂が電解液に溶出及び膨潤がしにくくなり、高い電池性能を維持することができる。 The lithium ion secondary battery of the present invention thus obtained is excellent in battery performance because it includes the electrode of the present invention. The reason why the battery performance is excellent is that the conductivity of the conductive assistant in the electrode slurry is excellent and the aggregation of the conductive assistant can be prevented. Furthermore, when the mixture layer contains the binder resin or the binder resin composition of the present invention, the binder resin is less likely to dissolve and swell in the electrolytic solution, and high battery performance can be maintained.
以下、実施例により本発明を具体的に説明するが、本発明は以下の実施例に限定されるものではない。
［バインダ樹脂の製造］
＜製造例１＞
脱イオン水７０質量部に対し、構成単位（ａ）としてＮ−ビニルホルムアミド（分子量７１．０８）２２．５質量部と構成単位（ｂ）としてアクリル酸（分子量７２．０６）に無機塩として水酸化ナトリウム（分子量４０．００）を混合し、ｐＨを６．７に調整したものを７．５質量部、次亜リン酸ナトリウム０．０１質量部を添加して作製した単量体水溶液を、リン酸によりｐＨ＝６．３となるよう調節し、単量体調節液を得た。この単量体調節液を５℃まで冷却した後、温度計を取り付けた断熱反応容器に入れ、１５分間窒素曝気を行った。その後、４、４’−アゾビス（４−シアノバレリックアシッド）（和光純薬工業株式会社製、「ＶＡ−０５７」）１０質量％水溶液を０．４質量部添加し、次いで、ｔ−ブチルハイドロパーオキサイド１０質量％水溶液および亜硫酸水素ナトリウム１０質量％水溶液をそれぞれ０．１質量部添加して重合を行った。内温がピークを超えた後さらに１時間熟成し、ゲルを取り出しミートチョッパーを通した後、６０℃で１０時間乾燥し、得られた固体を粉砕し、重合体（バインダ樹脂１）を得た。
EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.
[Manufacture of binder resin]
<Production Example 1>
With respect to 70 parts by mass of deionized water, 22.5 parts by mass of N-vinylformamide (molecular weight 71.08) as the structural unit (a) and water as an inorganic salt with acrylic acid (molecular weight 72.06) as the structural unit (b) A monomer aqueous solution prepared by adding 7.5 parts by mass of sodium oxide (molecular weight 40.00) and adjusting the pH to 6.7, and 0.01 parts by mass of sodium hypophosphite, The pH was adjusted to 6.3 with phosphoric acid to obtain a monomer adjusting solution. After cooling this monomer control liquid to 5 degreeC, it put into the heat insulation reaction container which attached the thermometer, and nitrogen aeration was performed for 15 minutes. Thereafter, 0.4 parts by mass of 10% by mass aqueous solution of 4,4′-azobis (4-cyanovaleric acid) (manufactured by Wako Pure Chemical Industries, Ltd., “VA-057”) was added, and then t-butyl hydro Polymerization was carried out by adding 0.1 parts by weight of a 10% by weight aqueous peroxide solution and a 10% by weight aqueous sodium hydrogen sulfite solution. After the internal temperature exceeded the peak, it was further aged for 1 hour, the gel was taken out, passed through a meat chopper, dried at 60 ° C. for 10 hours, and the resulting solid was pulverized to obtain a polymer (binder resin 1). .
<製造例２>
重合に使用する無機塩を水酸化カリウムとしてpHを６．７に調整した単量体水溶液を重合に供する以外は製造例１と同様にして重合体（バインダ樹脂２）を得た。
<Production example 2>
A polymer (binder resin 2) was obtained in the same manner as in Production Example 1, except that an aqueous monomer solution adjusted to pH 6.7 using potassium hydroxide as the inorganic salt for polymerization was used for the polymerization.
<製造例３>
重合に使用する構成単位（ａ）の単量体としてＮ−ビニルホルムアミド３０質量部を使用し、構成単位（ｂ）、無機塩を使用しない以外は製造例１と同様にして重合体（バインダ樹脂３）を得た。
<Production Example 3>
A polymer (binder resin) was prepared in the same manner as in Production Example 1 except that 30 parts by mass of N-vinylformamide was used as the monomer of the structural unit (a) used for the polymerization, and that the structural unit (b) and the inorganic salt were not used. 3) was obtained.
<製造例４>
重合に使用する無機塩を水酸化リチウムとしてpHを６．７に調整した単量体水溶液を重合に供する以外は製造例１と同様にして重合体（バインダ樹脂４）を得た。
<Production Example 4>
A polymer (binder resin 4) was obtained in the same manner as in Production Example 1 except that an aqueous monomer solution adjusted to pH 6.7 using lithium salt as the inorganic salt for polymerization was used for the polymerization.
［実施例１］
＜導電助剤分散性評価サンプルの作製＞
製造例１で得られたバインダ樹脂１を０．０４ｇと水１．９６ｇを自公転ミキサー（自転１０００ｒｐｍ、公転２０００ｒｐｍ、Ｔｈｉｎｋｙ社製 泡とり練太郎、以下、ミキサー）で混練した。得られたバインダ樹脂水溶液に導電助剤としてアセチレンブラック（電気化学工業（株）製）０．０１gを加え、スターラーを用いて１５０ｒｐｍで１５ｍｉｎ混練したものを評価サンプルとした。
[Example 1]
<Preparation of conductive auxiliary agent dispersibility evaluation sample>
0.04 g of binder resin 1 obtained in Production Example 1 and 1.96 g of water were kneaded with a revolving mixer (rotating rotation 1000 rpm, revolving 2000 rpm, manufactured by Thinky, Awatori Kentaro, hereinafter a mixer). To the obtained aqueous binder resin solution, 0.01 g of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.) was added as a conductive auxiliary agent, and kneaded at 150 rpm for 15 min using a stirrer was used as an evaluation sample.
<目視による評価>
上に記載した操作で得られた導電助剤分散性評価サンプルを目視で評価した。評価サンプル中に導電助剤が均一に分散しているものを○、導電助剤に凝集が見られるものを×として評価した。評価結果を表２に記載する。
<Visual evaluation>
The conductive auxiliary agent dispersibility evaluation sample obtained by the operation described above was visually evaluated. The evaluation sample was evaluated as “◯” when the conductive auxiliary agent was uniformly dispersed, and “X” when the conductive auxiliary agent was aggregated. The evaluation results are shown in Table 2.
［実施例２、比較例１、２］
使用するバインダ樹脂をバインダ樹脂２〜４とする以外は実施例１の方法と同様にバインダ樹脂水溶液、導電助剤分散性評価サンプルを得、評価を実施した。評価結果を表２に示す。
[Example 2, Comparative Examples 1 and 2]
A binder resin aqueous solution and a conductive auxiliary agent dispersibility evaluation sample were obtained and evaluated in the same manner as in Example 1 except that the binder resin used was changed to binder resins 2 to 4. The evaluation results are shown in Table 2.
表２から明らかなように、本発明におけるバインダ樹脂は、導電助剤の分散性に優れており、導電助剤の凝集を防止することが可能である。
比較例１に示すバインダ樹脂３であるＮ−ビニルホルムアミド単独重合体は、導電助剤の分散性を発揮する構成単位（ｂ）を含まないため、導電助剤の分散に不足が見られ、導電助剤の凝集が発生している。
また、比較例２に示すバインダ樹脂４であるＮ−ビニルホルムアミドとアクリル酸に無機塩として水酸化リチウムを用いた共重合体は、金属イオンとして周期表における１族、２族、１１族、１２族における３周期目以降に含まれていないリチウムイオンを使用しているため、導電助剤の分散に不足が見られ、導電助剤の凝集が発生している。
As is clear from Table 2, the binder resin in the present invention is excellent in the dispersibility of the conductive auxiliary agent, and can prevent aggregation of the conductive auxiliary agent.
The N-vinylformamide homopolymer, which is the binder resin 3 shown in Comparative Example 1, does not contain the structural unit (b) that exhibits the dispersibility of the conductive auxiliary agent. Aggregation of the auxiliary agent has occurred.
Moreover, the copolymer which used lithium hydroxide as an inorganic salt for N-vinylformamide which is binder resin 4 shown in Comparative Example 2 and acrylic acid as an inorganic salt is a group 1, group 2, group 11, 12 in the periodic table as a metal ion. Since lithium ions that are not contained after the third period in the group are used, the dispersion of the conductive auxiliary agent is insufficient, and the conductive auxiliary agent is aggregated.
Claims (7)
金属塩を形成している酸性基を有する構成単位（ｂ）と、を含む重合体からなる非水系二次電池電極用バインダ樹脂の製造方法であって、
前記金属塩を形成する金属イオンが周期表の１族、２族、１１族、１２族における３周期目以降に含まれるいずれかであり、
前記構成単位（ａ）由来の単量体と前記構成単位（ｂ）由来の単量体とを含む溶液に前記金属イオンを添加した後、重合することで前記重合体を得る、非水系二次電池電極用バインダ樹脂の製造方法。
A structural unit (b) having an acidic group forming a metal salt, and a method for producing a binder resin for a non-aqueous secondary battery electrode comprising a polymer comprising:
The metal ion forming the metal salt is any one included in the third and subsequent periods in Groups 1, 2, 11, and 12 of the periodic table.
A non-aqueous secondary that obtains the polymer by polymerization after adding the metal ion to a solution containing the monomer derived from the structural unit (a) and the monomer derived from the structural unit (b) A method for producing a binder resin for battery electrodes.
得られた前記二次電池電極用バインダ樹脂、あるいは前記非水系二次電池電極用バインダ樹脂組成物と、活物質とを溶媒に分散させて調製する、電極スラリーの調製方法。 The binder resin for secondary battery electrodes is manufactured by the manufacturing method of the binder resin for nonaqueous secondary battery electrodes as described in any one of Claims 1-3, or the nonaqueous secondary battery electrode of Claim 4 While producing a binder resin composition for non-aqueous secondary battery electrodes by a method for producing a binder resin composition for a battery,
A method for preparing an electrode slurry, which is prepared by dispersing the obtained binder resin for a secondary battery electrode or the binder resin composition for a non-aqueous secondary battery electrode and an active material in a solvent .
得られた前記非水系二次電池用電極を電解液とともに金属ケーシングに収容する、リチウムイオン二次電池の製造方法。 While manufacturing the electrode for non-aqueous secondary batteries by the manufacturing method of the electrode for non-aqueous secondary batteries of Claim 6 ,
The manufacturing method of a lithium ion secondary battery which accommodates the obtained said electrode for non-aqueous secondary batteries in a metal casing with electrolyte solution .
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