JP2015176816A - Binder for batteries - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder for batteries which makes it possible to offer a battery improved in initial discharge capacity, initial charge and discharge efficiencies, and cycle characteristics.SOLUTION: A binder for batteries comprises: a polymer having, as a main repeating unit, a structural unit expressed by the following general formula. (In the formula, Rand R, which may be identical to each other or not, each represent a group selected from: an alkyl group or halogenated alkyl group with 1-8 carbon atoms; an alkyl group or halogenated alkyl group having an aromatic ring with 7-20 carbon atoms; an alkyl group or halogenated alkyl group having an ether bond and an aromatic ring with 7-20 carbon atoms; and an alkyl group or halogenated alkyl group having ether bond with 2-8 carbon atoms.)

Description

  The present invention relates to a battery binder.

  In recent years, there has been a demand for the development of a high-capacity and long-life battery as a power source for mobile phones, notebook computers, tablet terminals, electric vehicles (EVs), and the like.

  A battery generally has a structure in which a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer or separator, a negative electrode active material layer, and a negative electrode current collector are laminated in this order. Hereinafter, the positive electrode current collector and the negative electrode current collector may be collectively referred to as an electrode current collector, and the positive electrode active material and the negative electrode active material may be collectively referred to as an electrode active material.

  The positive electrode active material layer, the negative electrode active material layer, and the optional solid electrolyte layer generally include solid materials such as a positive electrode active material, a negative electrode active material, and a solid electrolyte, respectively. These solid materials are generally powders.

  Therefore, in order to bind the solid materials contained in the positive electrode active material layer, the negative electrode active material layer, and the optional solid electrolyte layer, these layers generally include a binder in addition to the above solid materials. is there.

  Further, in the positive electrode active material layer and the negative electrode active material layer, a solid material and an electrode current collector are brought into close contact with each other by using a binder to prevent separation of the layers.

  As such a battery binder, for example, a battery binder containing polyvinylidene fluoride (PVdF) as described in Patent Document 1 is known. PVdF is frequently used as a battery binder because it has high mechanical strength, chemical resistance, and excellent electrical characteristics.

  Patent Document 2 describes a battery binder containing a tetracarboxylic acid ester compound, a diamine compound, and an organic solvent. This battery binder is described that a tetracarboxylic acid ester compound and a diamine compound form an imide at the time of drying or sintering, and a high binding force can be expected.

JP 2013-041807 A JP 2009-302046 A

  An object of the present invention is to provide a battery binder and an electrode that can provide a battery having improved initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics.

  Another object of the present invention is to provide a battery excellent in initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics.

  By the way, in the technical field of semiconductors, for example, a polymer represented by the following formula obtained by polymerizing 7,8-bis (alkoxycarbonyl) -7,8-dicyanoquinodimethane has high UV sensitivity. It is known to be useful as a resist material (see, for example, JP-A-61-7836):

Here, R ¹ and R ² are alkyl groups.

  Such polymers are typically not as flexible as battery binders because they are much more flexible than expected from rigid chemical structures with phenylene and tetrasubstituted ethylene (eg, Shouji Iwatuki, et al. 3 names, “Polymerization Behavior of 7,8-Bis (butoxycarbonyl) -7,8-dicyanquinodimethane”, Macromolecules, 1985, Vol. 18, No. 12, pages 2726-2732).

  However, as a result of intensive studies, the present inventors have found that when a binder including such a polymer having a specific substituent is used, a battery having improved initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics is obtained. The present inventors have found that it can be provided and have arrived at the present invention described below.

（式中、Ｒ^１及びＲ^２は、互いに同一又は異なって、炭素数１〜８のアルキル基又はハロゲン化アルキル基、炭素数７〜２０の芳香環を有するアルキル基又はハロゲン化アルキル基、炭素数７〜２０のエーテル結合と芳香環とを有するアルキル基又はハロゲン化アルキル基、及び炭素数２〜８のエーテル結合を有するアルキル基又はハロゲン化アルキル基からなる群から選択された基である）。
〈２〉Ｒ^１及びＲ^２がｎ―ブチル基である、〈１〉項に記載の電池用バインダ。
〈３〉電極集電体上に電極活物質層を有する電極であって、電極活物質層は、下記の一般式で示される構造単位を主たる繰り返し単位として有するポリマーを含む、電極：

（式中、Ｒ^１及びＲ^２は、互いに同一又は異なって、炭素数１〜８のアルキル基又はハロゲン化アルキル基、炭素数７〜２０の芳香環を有するアルキル基又はハロゲン化アルキル基、炭素数７〜２０のエーテル結合と芳香環とを有するアルキル基又はハロゲン化アルキル基、及び炭素数２〜８のエーテル結合を有するアルキル基又はハロゲン化アルキル基からなる群から選択された基である）。
〈４〉Ｒ^１及びＲ^２がｎ―ブチル基である、〈３〉項に記載の電極。
〈５〉正極集電体、正極活物質層、固体電解質層若しくはセパレータ、負極活物質層、及び負極集電体をこの順に有する電池であって、正極活物質層、負極活物質層、及び固体電解質層の少なくとも一つに、下記の一般式で示される構造単位を主たる繰り返し単位として有するポリマーを含む、電池：

（式中、Ｒ^１及びＲ^２は、互いに同一又は異なって、炭素数１〜８のアルキル基又はハロゲン化アルキル基、炭素数７〜２０の芳香環を有するアルキル基又はハロゲン化アルキル基、炭素数７〜２０のエーテル結合と芳香環とを有するアルキル基又はハロゲン化アルキル基、及び炭素数２〜８のエーテル結合を有するアルキル基又はハロゲン化アルキル基からなる群から選択された基である）。
〈６〉Ｒ^１及びＲ^２がｎ―ブチル基である、〈５〉項に記載の電池。 <1> A battery binder including a polymer having a structural unit represented by the following general formula as a main repeating unit:

Wherein R ¹ and R ² are the same or different from each other, and are an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, carbon A group selected from the group consisting of an alkyl group or halogenated alkyl group having an ether bond of 7 to 20 and an aromatic ring, and an alkyl group or halogenated alkyl group having an ether bond of 2 to 8 carbon atoms) .
<2> The battery binder according to <1>, wherein R ¹ and R ² are n-butyl groups.
<3> An electrode having an electrode active material layer on an electrode current collector, wherein the electrode active material layer includes a polymer having a structural unit represented by the following general formula as a main repeating unit:

Wherein R ¹ and R ² are the same or different from each other, and are an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, carbon A group selected from the group consisting of an alkyl group or halogenated alkyl group having an ether bond of 7 to 20 and an aromatic ring, and an alkyl group or halogenated alkyl group having an ether bond of 2 to 8 carbon atoms) .
<4> The electrode according to <3>, wherein R ¹ and R ² are n-butyl groups.
<5> A battery including a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer or separator, a negative electrode active material layer, and a negative electrode current collector in this order, the positive electrode active material layer, the negative electrode active material layer, and the solid A battery comprising at least one of the electrolyte layers including a polymer having a structural unit represented by the following general formula as a main repeating unit:

Wherein R ¹ and R ² are the same or different from each other, and are an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, carbon A group selected from the group consisting of an alkyl group or halogenated alkyl group having an ether bond of 7 to 20 and an aromatic ring, and an alkyl group or halogenated alkyl group having an ether bond of 2 to 8 carbon atoms) .
<6> The battery according to <5>, wherein R ¹ and R ² are n-butyl groups.

  According to the present invention, it is possible to provide a battery binder and an electrode that can improve the initial discharge capacity, the initial charge / discharge efficiency, and the cycle characteristics of the battery.

  According to the present invention, it is possible to provide a battery excellent in initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics.

FIG. 1 is a graph showing initial charge / discharge profiles of the battery of Example 1 and the battery of the comparative example. FIG. 2 is an enlarged graph of the capacity 0 to 10 mAh / g portion of the initial charge profile shown in FIG. FIG. 3 is a graph showing cycle characteristics of the battery of Example 1 and the battery of the comparative example.

《Binder for battery》
The battery binder of the present invention is a battery binder including a polymer having a structural unit represented by the following general formula 1 as a main repeating unit.

In Formula 1, R ¹ and R ² are the same or different from each other, and are an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, carbon It is a group selected from the group consisting of an alkyl group or halogenated alkyl group having an ether bond of 7 to 20 and an aromatic ring, and an alkyl group or halogenated alkyl group having an ether bond of 2 to 8 carbon atoms.

  Hereinafter, for convenience, 7,8-bis (alkoxycarbonyl) -7,8-dicyanoquinodimethane is also referred to as ACQ, and a polymer obtained by polymerizing ACQ as a main repeating unit is also referred to as p-ACQ.

  Although not bound by theory, conventional battery binders are excellent in binding between solid materials such as a positive electrode active material, a negative electrode active material, and a solid electrolyte, but cause a decomposition reaction of a solid electrolyte or a liquid electrolyte. Or the binder reaction may be decomposed by an electrode reaction to cause peeling between the electrode active material and the electrode current collector, which may lead to a decrease in capacity and a decrease in cycle characteristics. On the other hand, the battery binder of the present invention can reduce the decomposition reaction of the electrolyte by containing p-ACQ, and also reduces the separation between the electrode active material and the electrode current collector. Therefore, it is considered that the initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics of the battery can be improved.

<P-ACQ>
In the present invention, p-ACQ is a polymer having a structural unit represented by the following general formula 1 as a main repeating unit:

Here, R ¹ and R ² are the same as or different from each other, and an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, or a carbon number It is selected from the group consisting of an alkyl group or halogenated alkyl group having a 7-20 ether bond and an aromatic ring, and an alkyl group or halogenated alkyl group having a C2-8 ether bond.

  Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, such as an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group, and a pentyl group and isomers thereof. Etc.

  The halogenated alkyl group generally means a group in which at least one of hydrogen atoms of the alkyl group is substituted with a halogen element such as fluorine, chlorine, bromine, or iodine. Examples of the halogenated alkyl group include a fluorinated alkyl group, an alkyl chloride group, an alkyl bromide group, and an alkyl iodide group. Further, the halogen to be replaced need not be the same, and for example, —CHClF and the like are also included in the halogenated alkyl group.

The alkyl group having an ether bond means an alkyl group having at least one ether bond, such as a methoxymethyl group (—CH ₂ —O—CH ₃ ), a methoxyethyl group (—CH ₂ CH ₂ —O—). CH ₃ ), 2-methoxyethoxymethyl group (—CH ₂ —O—CH ₂ CH ₂ —O—CH ₃ ), and the like.

In general, an alkyl group having an aromatic ring is an alkyl group in which at least one of the hydrogen atoms of the alkyl group is substituted with an aromatic ring such as a benzene ring, a naphthalene ring, an anthracene ring, etc., and does not have an ether bond. Meaning, for example, benzyl group (PhCH ₂ —), phenylethyl group (PhCH ₂ CH ₂ —), naphthylmethyl group (NAPCH ₂ —), naphthylethyl group (NAPCH ₂ CH ₂ —), anthracenylmethyl group ( ANTCH _2- ) and the like.

  The lower limit of the carbon number of the alkyl group having an aromatic ring can be 7 or more, such as 8 or more, or 11 or more, and the upper limit can be 20 or less, such as 15 or less, or 12 or less.

  The alkyl group having an ether bond and an aromatic ring generally means an alkyl group having at least one ether bond and having at least one aromatic ring. For example, (1) at least one of the hydrogen atoms of the alkyl group. An alkyl group substituted with an aromatic oxy group, such as a phenoxy group, a naphthoxy group, an anthracenoxy group, or the like, or (2) at least one of the hydrogen atoms of the alkyl group is an aromatic ring, such as a benzene ring, naphthalene ring, anthracene ring And an alkyl group substituted with at least one ether bond.

Examples of the group (1) include a phenoxyethyl group (Ph—O—CH ₂ CH ₂ —), a naphthoxyethyl group (NAP—O—CH ₂ CH ₂ —), and an anthracenoxyethyl group (ANT—O—CH). ₂ CH ₂ —) and the like.

Examples of the group (2) include a benzyloxymethyl group (Ph—CH ₂ —O—CH ₂ —), a benzyloxyethyl group (Ph—CH ₂ —O—CH ₂ CH ₂ —) and the like. it can.

  The lower limit of the carbon number of the alkyl group having an ether bond and an aromatic ring can be 7 or more, for example, 8 or more, or 11 or more, and the upper limit is 20 or less, for example, 15 or less, or 12 or less. it can.

  The “main repeating unit” in the present invention means a repeating unit constituting 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more based on the number of moles of the repeating unit.

  The number of repeating structural units of Formula 1 is related to the number average molecular weight (Mn) of p-ACQ and the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn).

  The upper limit of the number average molecular weight (Mn) of p-ACQ is not particularly limited, and can be, for example, 800,000 or less, preferably 500,000 or less. The lower limit of the number average molecular weight (Mn) of p-ACQ is not particularly limited as long as a desired binding force is obtained, and can be, for example, 100,000 or more, for example, 400,000 or more.

  The upper limit of the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of p-ACQ is not particularly limited, and varies depending on the polymerization method, polymerization conditions, etc., for example, 10 or less, preferably 1. It can be 5 or less.

  p-ACQ can be obtained by polymerizing 7,8-bis (alkoxycarbonyl) -7,8-dicyanoquinodimethane (ACQ) by any method.

  As a method for producing ACQ, for example, JP-A-61-7836 can be referred to, and α, α′-bis (alkoxycarbonyl) -p-xylyl can be referred to in a solvent such as acetonitrile. An example is a method in which N-chlorosuccinimide (NCS) and triethylamine (TEA) are allowed to act on range cyanide to obtain ACQ.

  The method for polymerizing ACQ is not limited, but any method such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and the like can be used.

  For example, there is a method in which ACQ is polymerized by dissolving ACQ in a solvent such as acetonitrile to obtain p-ACQ.

  The conditions for polymerizing ACQ can be arbitrarily selected according to the degree of polymerization of the target p-ACQ, the molecular weight distribution, and the like.

<Method of manufacturing battery binder>
In addition to the p-ACQ of the general formula 1, the battery binder of the present invention may optionally include other polymers such as polyvinylidene fluoride (PVdF) and solvents such as N-methyl-2-pyrrolidone (NMP). An additive may be further included.

  The battery binder of the present invention can be produced by mixing these materials by an arbitrary method.

  When the battery binder contains a solvent, when forming the electrode active material layer or the solid electrolyte layer, the p-ACQ can be easily dispersed in the layer, and the solid materials and the solid material and the electrode current collector can be dispersed. It may be advantageous in terms of obtaining good adhesion.

  Even when the battery binder does not contain a solvent, such a solvent can be optionally added in either the electrode active material layer or the step of forming the solid electrolyte layer.

"electrode"
The electrode of the present invention is an electrode having an electrode active material layer on an electrode current collector, and the electrode active material layer includes an electrode having a polymer having the structural unit represented by the general formula 1 as a main repeating unit. It is.

  For details on p-ACQ, see the description in the Binder section.

  The electrode of the present invention has improved initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics by including p-ACQ in the positive electrode active material layer in the case of the positive electrode and in the negative electrode active material layer in the case of the negative electrode. A battery having the same can be provided.

  The electrode of the present invention may be a positive electrode or a negative electrode. Preferably, the electrode of the present invention is a positive electrode. The positive electrode generally has a structure in which a positive electrode active material layer is formed on a positive electrode current collector. The negative electrode generally has a structure in which a negative electrode active material layer is formed on a negative electrode current collector.

<Electrode current collector>
The electrode current collector refers to a positive electrode current collector in the case of a positive electrode, and refers to a negative electrode current collector in the case of a negative electrode, and has a function of collecting current from the electrode active material layer. Examples of the material for the electrode current collector include metals or alloys such as aluminum, copper, stainless steel (SUS), nickel, iron, and titanium. Moreover, examples of the shape of the current collector include a foil shape, a plate shape, a mesh shape, and a porous body.

<Electrode active material layer>
An electrode active material layer refers to a positive electrode active material layer in the case of a positive electrode, and a negative electrode active material layer in the case of a negative electrode. The positive electrode active material layer includes a positive electrode active material and p-ACQ, and optionally includes additives such as a solid electrolyte and a conductive aid. The negative electrode active material layer includes a negative electrode active material and p-ACQ, and optionally includes additives such as a solid electrolyte and a conductive aid.

  The positive electrode active material may be any material that can occlude ions such as lithium, sodium, and calcium during discharge and can optionally be released during charge.

For example, in the case of a positive electrode for a lithium ion battery, examples of the positive electrode active material include, but are not limited to, a layered lithium oxide such as LiCoO ₂ represented by LiMO ₂ .

  The negative electrode active material can be any material that can release ions such as lithium, sodium, and calcium during discharge and can optionally be occluded during charging.

  As a solid electrolyte, it can be set as arbitrary materials which have ion conductivity, such as lithium, sodium, and calcium, and are solid at normal temperature, for example, 15 to 25 degreeC.

For example, in the case of a lithium ion battery, sulfide solid electrolytes such as Li ₂ S—P ₂ S ₅ and oxide solid electrolytes such as Li ₂ O—B ₂ O ₃ —P ₂ O ₅ can be mentioned.

  Although it will not specifically limit as a conductive support agent if the electroconductivity of an electrode active material layer can be improved, Carbon materials, such as carbon black (CB) and acetylene black (AB), can be mentioned.

<Method for producing electrode>
The method for producing the electrode is not particularly limited as long as the electrode active material layer can be formed on the electrode current collector. For example, the electrode active material and materials such as p-ACQ are dispersed in an arbitrary dispersion medium. Examples include a method in which a slurry is formed, and the resulting slurry is coated on an electrode current collector by an arbitrary method and dried.

"battery"
A battery according to the present invention is a battery having a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer or separator, a negative electrode active material layer, and a negative electrode current collector in this order, the positive electrode active material layer, the negative electrode active material layer In addition, at least one of the optional solid electrolyte layers includes a polymer having the structural unit represented by the general formula 1 as a main repeating unit.

  Although the battery by this invention is not limited, For example, metal ion batteries, such as a lithium ion battery, a calcium ion battery, a sodium ion battery, are mentioned. The electrolyte used for the battery may be a solid electrolyte or a liquid electrolyte.

  Details of the polymer having the structural unit represented by the general formula 1 as a main repeating unit, that is, p-ACQ, and the positive electrode current collector, the positive electrode active material layer, the negative electrode active material layer, and the negative electrode current collector See the description in the binder and electrode section.

  The battery of the present invention includes p-ACQ in at least one of the positive electrode active material layer, the negative electrode active material layer, and the optional solid electrolyte layer, so that the initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics of the battery are increased. Can be improved.

<Battery manufacturing method>
The battery manufacturing method of the present invention uses any method as long as the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer or separator, the negative electrode active material layer, and the negative electrode current collector can be laminated in this order. be able to.

  For example, a positive electrode active material layer is laminated on a positive electrode current collector as described above, and a solid electrolyte layer or separator is stacked thereon and pressed, and the negative electrode current collector is collected on the solid electrolyte layer or separator as described above. It can be manufactured by stacking and pressing a negative electrode active material layer formed in advance on an electric body.

  <Other components>

  When a separator is used instead of the solid electrolyte layer, generally, a laminate in which a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode current collector are laminated in this order is optionally placed in a battery case. Inject liquid electrolyte.

  As the liquid electrolyte, any material can be used as long as it has ionic conductivity such as lithium, sodium, and calcium and is liquid at room temperature, for example, 15 ° C. to 25 ° C.

  Examples of the liquid electrolyte include, but are not limited to, carbonate-based electrolytes, and more specifically, cyclic carbonate-based electrolytes such as propylene carbonate (PC) and ethylene carbonate (EC), and chains of dimethyl carbonate (DMC). And fluorinated carbonate electrolytes such as fluoroethylene carbonate, and combinations thereof.

Example 1
In Example 1, a polymer of 7,8-bis (butoxycarbonyl) -7,8-dicyanoquinodimethane (p-BCQ) in which R ¹ and R ² are both n-butyl ( ⁿ Bu) groups is used. A battery binder containing p-BCQ was synthesized. Moreover, a positive electrode was produced using this battery binder, and a battery was produced by combining the obtained positive electrode and negative electrode.

<Synthesis of BCQ>
α, α′-bis (butoxycarbonyl) -p-xylylene dicyanide (Compound 1) and N-chlorosuccinimide (NCS) are dissolved in acetonitrile (CH ₃ CN) and stirred at room temperature while triethylamine is stirred. (TEA) was added. The amount of each compound used was as shown in Table 1.

  As soon as TEA was added, the reaction solution turned yellow. After adding TEA, the reaction was carried out for the reaction times shown in Table 1.

  The reaction solution was filtered, and the residue was washed with isopropyl ether (IPE) containing a small amount of acetic acid, and the solvent was removed under reduced pressure to give 7,8-bis (butoxycarbonyl) -7,8-dicyano as a yellow powder. Quinodimethane (BCQ) was obtained. The yield and yield were as shown in Table 1.

  The reaction formula is shown in the following formula 2.

The structure of the obtained 7,8-bis (butoxycarbonyl) -7,8-dicyanoquinodimethane (BCQ) was confirmed by ¹ H NMR (CDCl ₃ ) and ¹³ C NMR (CDCl ₃ ). The results are shown below.

7,8-bis (butoxycarbonyl) -7,8-dicyanoquinodimethane: ¹ H NMR (CDCl ₃ ): δ = 0.98 (t, J = 7.5 Hz, 6H), 1.44 (m, 4H), 1.76 (m, 4H), 4.32 (t, J = 6.5 Hz, 4H), 7.77 (dd, J = 10.0 Hz, 2H), 8.48 (dd, J = 10.0 Hz, 2H). ¹³ C NMR (CDCl ₃ ): δ = 13.6, 19.0, 30.3, 66.8, 107.6, 115.3, 130.7, 132.7, 147.8, 161.1.

<Synthesis of p-BCQ>
7,8-bis (butoxycarbonyl) -7,8-dicyanoquinodimethane (BCQ) was polymerized by adding it in acetonitrile (CH ₃ CN) at room temperature. The amount of each compound used was as shown in Table 2. The reaction time was 30 minutes.

  After 30 minutes, the reaction solution was filtered, and the residue was washed with isopropyl ether (IPE) containing a small amount of acetic acid, and the solvent was removed under reduced pressure to remove 7,8-bis (butoxycarbonyl) -7,8. -A polymer of dicyanoquinodimethane (p-BCQ) was obtained.

  As shown in Table 1, this polymerization reaction was repeated 22 times to obtain 4.21 g of p-BCQ in a 96% yield.

  The reaction formula is shown in the following formula 3.

The structure of the obtained p-BCQ was confirmed by ¹ H NMR (CDCl ₃ ). The results are shown below.

Polymer of 7,8-bis (butoxycarbonyl) -7,8-dicyanoquinodimethane (p-BCQ): ¹ H NMR (CDCl ₃ ), δ = 0.90 (br, 6H), 1.36 (br , 4H), 1.67 (br, 4H), 4.27 (br, 4H), 8.48 (br, 4H).

<Production of battery binder>
The obtained p-BCQ was mixed with N-methyl-2-pyrrolidone (NMP) as a solvent so as to have a solid content of 5% to prepare a battery binder.

<Preparation of positive electrode>
16.5 g of the obtained battery binder and 2 g of N-methyl-2-pyrrolidone (NMP) were mixed for 5 minutes, and acetylene black (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive assistant was used. 0.94 g was added and mixed for another 5 minutes.

Next, 10 g of LiNi _0.5 Mn _1.5 O ₄ as a positive electrode active material is added, the viscosity is confirmed appropriately, and NMP is added so that a desired viscosity is obtained, and mixed for 10 minutes, A slurry was obtained.

  The mass ratio of positive electrode active material: binder for battery: conductive aid in the obtained slurry was 85: 8: 7.

  The obtained slurry was manually applied onto an aluminum foil as a positive electrode current collector having a thickness of 15 μm by using a doctor blade method and pressed by a roll press, whereby the positive electrode active material layer was formed into a positive electrode current collector. And stuck.

  Next, the positive electrode active material layer was dried, and a positive electrode active material layer was formed on the positive electrode current collector to produce a positive electrode.

<Production of battery>
On the positive electrode active material layer of the obtained positive electrode, a separator and a graphite negative electrode were stacked and pressed together. The obtained laminate was placed in a coin-type battery case, and a carbonate-type electrolyte was poured into the battery case to produce a coin-type battery.

Example 2
In Example 2, a battery binder containing p-BCQ and PVdF at a mass ratio of p-BCQ: PVdF = 1: 1 was prepared. Moreover, a positive electrode was produced using this battery binder, and a battery was produced by combining the obtained positive electrode and negative electrode.

  p-BCQ was synthesized in the same manner as in Example 1.

  The obtained p-BCQ and PVdF (KF polymer L # 7305, manufactured by Kureha) in a mass ratio of p-BCQ: PVdF = 1: 1 in N-methyl-2-pyrrolidone (NMP) as a solvent. In addition, a battery binder was prepared by mixing so that the solid content was 5%.

  Using the obtained battery binder, a positive electrode and a battery were produced in the same manner as in Example 1.

Example 3
In Example 3, a battery binder containing p-BCQ and PVdF at a mass ratio of p-BCQ: PVdF = 1: 9 was produced. Moreover, a positive electrode was produced using this battery binder, and a battery was produced by combining the obtained positive electrode and negative electrode.

  p-BCQ was synthesized in the same manner as in Example 1.

  The obtained p-BCQ and PVdF (KF polymer L # 7305, manufactured by Kureha) in a mass ratio of p-BCQ: PVdF = 1: 9 in N-methyl-2-pyrrolidone (NMP) as a solvent. In addition, a battery binder was prepared by mixing so that the solid content was 5%.

  Using the obtained battery binder, a positive electrode and a battery were produced in the same manner as in Example 1.

《Comparative example》
As a comparative example, PVdF (KF polymer L # 7305, manufactured by Kureha) was mixed with N-methyl-2-pyrrolidone (NMP) as a solvent so that the solid content was 5%. Produced.

  Using the obtained battery binder, a positive electrode and a battery were produced in the same manner as in Example 1.

<Evaluation>
<Charge / discharge test>
The charge / discharge test was conducted under the following conditions. That is, a constant current corresponding to 0.3 C was applied to the battery to perform constant current charging (CC charging) up to 4.9 V, and the charging profile at this time was measured. Further, constant current discharge (CC discharge) was performed at a constant current value equivalent to 0.3 C until the voltage reached 3.5 V, and the discharge profile at this time was measured.

  The charge / discharge test was performed at a room temperature of 25 ° C., with the above CC charge and CC discharge as one cycle, and three cycles.

  The initial charge / discharge profile is shown in FIG. Moreover, the enlarged view of the range of the capacity | capacitance 0-10mAh / g of the charge profile shown in FIG. 1 is shown in FIG.

  The discharge profile shown in FIG. 1 indicates that the batteries of Examples 1 to 3 were on the high capacity side compared to the battery of the comparative example, and therefore, a larger capacity could be discharged. The charging profiles shown in FIGS. 1 and 2 indicate that the batteries of Examples 1 to 3 had a higher charging voltage than the batteries of the comparative examples, and thus were able to charge a higher capacity.

<Cycle charge / discharge test>
A cycle charge / discharge test was performed under the following conditions. That is, a constant current equivalent to 2C is applied to the battery, constant current charging is performed, charging is performed to 4.9V, and then the current is decreased so as to maintain the voltage of 4.9V, and low voltage charging is performed. When the current dropped to 0.15C equivalent, charging was stopped (CCCV charging). Next, constant current discharge (CC discharge) was performed at a constant current value corresponding to 2C until the voltage reached 3.5V.

  The cycle charge / discharge test was performed at 60 ° C. and 100 cycles with the above CCCV charge and CC discharge as one cycle.

  The results of the cycle charge / discharge test are shown in FIG. FIG. 3 shows that the batteries of Examples 1 to 3 have a small decrease in capacity even after repeated discharging and charging as compared with the batteries of the comparative examples, and thus are more excellent in cycle characteristics.

  The test results of Examples 1 to 3 and Comparative Example are summarized in Table 3.

  In Table 3, the initial charge / discharge efficiency (%) indicates the ratio of the initial discharge capacity (mAh / g) to the initial charge capacity (mAh / g).

  The results in Table 3 show that the battery binders of Examples 1 to 3 have improved initial discharge capacity, initial charge / discharge efficiency, and cycle characteristics compared to the battery binder of the comparative example. Indicates that it was possible.

Claims (6)

A battery binder comprising a polymer having a structural unit represented by the following general formula as a main repeating unit:

Wherein R ¹ and R ² are the same or different from each other, and are an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, carbon A group selected from the group consisting of an alkyl group or halogenated alkyl group having an ether bond of 7 to 20 and an aromatic ring, and an alkyl group or halogenated alkyl group having an ether bond of 2 to 8 carbon atoms) . The battery binder according to claim ^1, wherein R ¹ and R ² are n-butyl groups. An electrode having an electrode active material layer on an electrode current collector, wherein the electrode active material layer includes a polymer having a structural unit represented by the following general formula as a main repeating unit:

Wherein R ¹ and R ² are the same or different from each other, and are an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, carbon It is a group selected from the group consisting of an alkyl group or halogenated alkyl group having an ether bond of 7 to 20 and an aromatic ring, and an alkyl group having an ether bond of 2 to 8 carbon atoms). The electrode according to claim 3, wherein R ¹ and R ² are n-butyl groups. A battery having a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer or separator, a negative electrode active material layer, and a negative electrode current collector in this order,
A battery including at least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer containing a polymer having a structural unit represented by the following general formula as a main repeating unit:

Wherein R ¹ and R ² are the same or different from each other, and are an alkyl group or halogenated alkyl group having 1 to 8 carbon atoms, an alkyl group or halogenated alkyl group having an aromatic ring having 7 to 20 carbon atoms, carbon A group selected from the group consisting of an alkyl group or halogenated alkyl group having an ether bond of 7 to 20 and an aromatic ring, and an alkyl group or halogenated alkyl group having an ether bond of 2 to 8 carbon atoms) . The battery according to claim 5, wherein R ¹ and R ² are n-butyl groups.

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