KR20120081983A - Electrode for secondary battery, binder for secondary battery electrode, and secondary battery - Google Patents

Abstract

The electrode for secondary batteries which contains the electrode active material layer which does not contain a halogen atom and contains the block polymer which does not contain an unsaturated bond in a principal chain is laminated | stacked on an electrical power collector. A secondary battery having a positive electrode, an electrolyte, a separator, and a negative electrode, wherein the positive electrode and / or the negative electrode is the electrode for the secondary battery. It is preferable that the said block copolymer consists of the segment which shows compatibility with electrolyte solution, and the segment which does not show compatibility with electrolyte solution.

Description

Electrode for Secondary Battery, Binder for Secondary Battery Electrode and Secondary Battery {ELECTRODE FOR SECONDARY BATTERY, BINDER FOR SECONDARY BATTERY ELECTRODE, AND SECONDARY BATTERY}

The present invention relates to a secondary battery electrode, a manufacturing method thereof, a binder constituting the electrode active material layer, and a battery using the secondary battery electrode.

Lithium ion secondary batteries show the highest energy density among practical batteries, and are particularly used for small electronics. In addition, development for automobile applications is also expected. Among them, further high performance, such as long life of a lithium ion secondary battery, operation in a wide temperature range, and improvement of safety, is desired.

The positive electrode (正極) of the lithium ion secondary battery, generally, lithium-containing metal oxides, such as LiCoO _2, LiMn ₂ O ₄ and LiFePO ₄ is used as the positive electrode active material or the like, combined by a binder, such as polyvinylidene fluoride Formed. On the other hand, the negative electrode is formed by bonding a carbonaceous (amorphous) carbon material, a metal oxide, a metal sulfide, or the like, which is used as a negative electrode active material, with a binder such as a styrene-butadiene copolymer.

For the high performance of a lithium ion secondary battery, patent document 1 discloses using styrene-butadiene-styrene block copolymer as a binder of the electrode which consists of an active material and a binder, for example. By using the styrene-butadiene-styrene block copolymer, desorption of the active material can be prevented and a battery having a low internal resistance is obtained.

In addition, Patent Document 2 discloses using a fluorine-containing block copolymer as a binder of an electrode composed of an active material and a binder. By using a fluorine-containing block copolymer composed of a fluorine-containing segment and a non-fluorine segment, an electrode excellent in the balance between the adhesion to the current collector and the electrolyte resistance is obtained.

Japanese Laid-Open Patent Publication 2000-133275 Japanese Unexamined Patent Publication No. 2002-141068

However, according to the studies of the present inventors, in the methods described in Patent Literatures 1 and 2, the polymer becomes unstable at a high temperature by having an unsaturated bond in the main chain of the block copolymer, or by having a halogen element in the structure. As a result, side reactions such as decomposition can occur, and as a result, it can be seen that high temperature characteristics such as high temperature cycle characteristics of the secondary battery are greatly reduced.

Moreover, in order to improve long-term cycling characteristics, it turns out that it is necessary to further improve electrolyte retention property and electrolyte solution impregnation of an electrode.

Therefore, an object of the present invention is to provide a secondary battery electrode for use in a lithium ion secondary battery or the like, in which high temperature characteristics and long term cycle characteristics are further improved.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors used the block copolymer which does not contain a halogen atom as a binder and does not contain an unsaturated bond in a main chain, and the side reactions, such as decomposition | decomposition of a polymer even in high temperature, are used. Since it did not produce | generate, it discovered that the high temperature characteristic and long-term cycle characteristic of the secondary battery using the electrode for secondary batteries which have this block copolymer improve, and came to complete this invention.

Thus, according to this invention, the electrode for secondary batteries provided with the electrode active material layer which contains a block copolymer which does not contain a halogen atom and does not contain an unsaturated bond in a main chain, and an electrode active material is laminated | stacked on the electrical power collector. do.

In this invention, it is preferable that a block copolymer consists of the segment which shows compatibility with electrolyte solution, and the segment which does not show compatibility with electrolyte solution. Since the block copolymer has the above structure, dispersibility is improved by high adsorption stability to the electrode active material, has high electrolyte retention and electrolyte impregnation, and can exhibit high output characteristics in addition to high long-term cycle characteristics.

That is, this invention which solves the said subject includes the following matter as a summary.

(1) An electrode for secondary batteries which has an electrical power collector and the electrode active material layer which consists of the block copolymer and electrode active material which do not contain a halogen atom, and do not contain an unsaturated bond in a main chain, formed on the said electrical power collector.

(2) The electrode for secondary batteries as described in (1) in which the said block copolymer has the segment which shows compatibility with the electrolyte solution containing ethylene carbonate and diethyl carbonate, and the segment which does not show compatibility with the said electrolyte solution.

(3) The electrode for secondary batteries as described in (1) or (2) in which the said block copolymer contains the segment of the soft polymer of 15 degrees C or less of glass transition temperature.

(4) The electrode for secondary batteries in any one of (1)-(3) whose weight average molecular weights of the said block copolymer are in the range of 1,000-500,000.

(5) A binder for secondary battery electrodes containing a block copolymer that does not contain a halogen atom and does not contain an unsaturated bond in the main chain.

(6) The binder for secondary battery electrodes as described in (5) in which the said block copolymer has the segment which shows compatibility with the electrolyte solution containing ethylene carbonate and diethyl carbonate, and the segment which does not show compatibility with the said electrolyte solution. .

(7) The binder for secondary battery electrodes as described in (5) or (6) in which the said block copolymer contains the segment of the soft polymer of 15 degrees C or less of glass transition temperature.

(8) The binder for secondary battery electrodes in any one of (5)-(7) whose weight average molecular weights of the said block copolymer are in the range of 1,000-500,000.

(9) (1) comprising a step of applying a slurry containing no halogen atoms and no unsaturated bonds in the main chain, and a slurry containing an electrode active material on a current collector and drying The manufacturing method of the electrode for secondary batteries in any one of? (4).

(10) A secondary battery having a positive electrode, an electrolyte, a separator, and a negative electrode,

The secondary battery whose said positive electrode and / or negative electrode is the electrode for secondary batteries in any one of (1)-(4).

According to the present invention, when the electrode for secondary batteries contains a specific binder, high dispersibility and high electrolyte retention of the electrode active material in the electrode for secondary batteries are achieved, and the high temperature characteristics and long-term cycle characteristics of the secondary battery obtained are Is improved.

The present invention is described in detail below.

The electrode for secondary batteries of this invention has an electrical power collector and the electrode active material layer containing the block copolymer which does not contain a halogen atom formed on the electrical power collector, and contains no unsaturated bond in a principal chain, and an electrode active material. The electrode active material layer of this invention contains an electrode active material and a block copolymer. Hereinafter, this structural material is demonstrated in detail.

(Electrode active material)

It is common to select the electrode active material used for the electrode for secondary batteries of this invention according to the secondary battery in which an electrode is used. As said secondary battery, a lithium ion secondary battery and a nickel hydrogen secondary battery are mentioned.

When the electrode for secondary batteries of this invention is used for a lithium ion secondary battery positive electrode, the active material which can occlude-release lithium ion is used, and the electrode active material (positive electrode active material) for lithium ion secondary battery positive electrodes consists of an inorganic compound, It is largely distinguished by what consists of organic compounds.

As a positive electrode active material which consists of inorganic compounds, transition metal oxide, transition metal sulfide, lithium containing composite metal oxide of lithium and a transition metal, etc. are mentioned. As the transition metal, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo and the like are used.

As the transition metal oxide, MnO, MnO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , Cu ₂ V ₂ O ₃ , amorphous V ₂ OP ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O include _13, etc., and among them from the cycling stability and the capacity of the secondary battery obtained _{MnO, V 2 O 5, V} 6 O 13, TiO 2 is preferred.

Examples of the transition metal sulfides include TiS ₂ , TiS ₃ , amorphous MoS ₂ , FeS, and the like.

As a lithium containing composite metal oxide, the lithium containing composite metal oxide which has a layered structure, the lithium containing composite metal oxide which has a spinel structure, the lithium containing composite metal oxide which has an olivine type structure, etc. are mentioned.

Lithium-containing composite metal oxides having a layered structure include lithium-containing cobalt oxide (LiCoO ₂ ), lithium-containing nickel oxide (LiNiO ₂ ), lithium composite oxide of Co-Ni-Mn, lithium composite oxide of Ni-Mn-Al, Ni And lithium composite oxides of -Co-Al.

A lithium-containing composite metal oxide having a spinel structure lithium manganese oxide (LiMn ₂ O ₄₎ and the substituting a part of Mn with other transition metal _{Li [Mn 3/2 M 1} /2] O 4 ( where M, Cr , Fe, Co, Ni, Cu and the like).

Examples of the lithium-containing composite metal oxide having an olivine-type structure include Li _X MPO ₄ (wherein M is Mn, Fe, Co, Ni, Cu, Mg, Zn, V, Ca, Sr, Ba, Ti, Al, and Si). And an olivine-type lithium phosphate compound represented by at least one selected from B, and Mo, 0 ≦ X ≦ 2). The iron oxide lacking in electrical conductivity may be used as an electrode active material covered with a carbon material by coexisting a carbon source material during reduction firing. Moreover, these compounds may be element substituted partially.

As the organic compound, for example, conductive polymers such as polyacetylene and poly-p-phenylene can be used.

The positive electrode active material for a lithium ion secondary battery may be a mixture of the above inorganic compound and organic compound. Although the particle diameter of a positive electrode active material is suitably selected by the balance with the other characteristic of a battery, from a viewpoint of the improvement of battery characteristics, such as a load characteristic and a cycle characteristic, a 50% volume cumulative diameter is normally 0.1-50 micrometers, Preferably 1-20 micrometers. If the 50% volume cumulative diameter is within this range, a secondary battery having a large charge / discharge capacity can be obtained, and handling at the time of producing the electrode active material slurry and the electrode is easy. The 50% volume cumulative diameter can be obtained by measuring the particle size distribution by laser diffraction.

When the electrode for secondary batteries of this invention is used for a lithium ion secondary battery negative electrode, As an electrode active material (negative electrode active material) for a lithium ion secondary battery negative electrode, For example, amorphous carbon, graphite, natural graphite, mesocarbon micro Carbonaceous materials, such as a bead and pitch type carbon fiber, Conductive polymers, such as polyacene, etc. are mentioned. Moreover, as a negative electrode active material, the single metal which forms lithium alloys, such as lithium metal, Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, Zn, etc. And alloys, and oxides and sulfides thereof are used. Among them, oxides such as silicon (Si), tin (Sn), or lead (Pb) single metal or alloys containing these atoms, tin oxide, manganese oxide, titanium oxide, niobium oxide, vanadium oxide, Si, Sn, Pb And lithium-containing metal composite oxide materials such as Li _x Ti _y M _z O ₄ containing a metal element selected from the group consisting of Ti atoms (0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, 0 ≦ z ≦ 1.6, M is Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and Nb). The electrode active material can also use the thing which made the electrically conductive agent adhere to the surface by the mechanical modification method. Although the particle size of a negative electrode active material is suitably selected by balance with the other structural requirements of a battery, 50% volume cumulative diameter is normally 1-50 micrometers from a viewpoint of the improvement of battery characteristics, such as initial efficiency, load characteristics, and a cycle characteristic. Preferably, it is 15-30 micrometers.

When the electrode for secondary batteries of this invention is used for the nickel hydride secondary battery positive electrode, nickel hydroxide particle | grains are mentioned as a positive electrode active material which can be used. The nickel hydroxide particles may be dissolved in cobalt, zinc, cadmium, or the like, or may be coated with a cobalt compound whose surface is subjected to alkali heat treatment.

When the electrode for secondary batteries of this invention is used for a nickel hydride secondary battery negative electrode, as an electrode active material (negative electrode active material) for a nickel hydride secondary battery negative electrode, a hydrogen storage alloy particle is electrochemically contained in alkaline electrolyte solution at the time of charge of a battery. The hydrogen may be occluded, and the hydrogen may be easily released at the time of discharge, and is not particularly limited. Particles composed of a hydrogen occlusion alloy of AB5 type, TiNi and TiFe type are preferable. Do. Specifically, for example, LaNi ₅ , MmNi ₅ (Mm is mischmetal), LmNi ₅ (Lm is at least one selected from rare earth elements containing La), and a part of Ni of these alloys is Al, Mn, Multi-element hydrogen-containing alloy particles substituted with one or more elements selected from Co, Ti, Cu, Zn, Zr, Cr, and B can be used. In particular, the hydrogen storage alloy particles having the composition represented _by LmNi _w Co _x Mn _y Al _z (the sum of atomic ratios w, x, y, z are 4.80 ≦ w + x + y + z ≦ 5.40) are used for the progress of the charge / discharge cycle. It is preferable because accompanying micronization is suppressed and the charge / discharge cycle characteristics are improved.

Among the electrode active materials for these secondary batteries, an electrode active material for lithium ion secondary batteries, in which long life, operation in a wide temperature range, and improvement in safety are most desired are desired. Especially, an inorganic compound is preferable and a lithium containing composite metal oxide is preferable at the point which densifies at the time of electrode manufacture, improves an energy density, and uses it, and the suppression effect of the thickness change after immersion is remarkable. Furthermore, by using the binder of the present invention, high conductivity can be exhibited even with a small amount of conductive agent. Therefore, the lithium-containing composite metal oxide having a layered structure and the lithium-containing composite metal oxide having a spinel structure are preferred because the conductivity of the active material is not too low, and is used using a small amount of a conductive agent. .

In this invention, the content rate of the electrode active material in an electrode active material layer becomes like this. Preferably it is 90-99.9 mass%, More preferably, it is 95-99 mass%. By making content of the electrode active material in an electrode active material into the said range, an electrode active material layer is excellent in binding property and flexibility, and a secondary battery has a high capacity.

(Block copolymer)

The electrode active material layer of the electrode for secondary batteries of this invention contains the block copolymer which does not contain a halogen atom and does not contain an unsaturated bond in a principal chain.

The block copolymer used in the present invention is preferably a block copolymer having two kinds of segments (segment A, segment B).

Since the block copolymer used in the present invention does not contain a halogen atom and does not contain an unsaturated bond in the main chain, the polymer is stabilized even at a high temperature, and side reactions such as decomposition of the polymer can also be suppressed. Thereby, the high temperature characteristic of a secondary battery electrode, especially high temperature cycling characteristics improve significantly. The halogen atom which is not contained in a block copolymer belongs to the element of group 17 of the periodic table, and a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and an asstatin atom correspond.

In the present invention, the block copolymer does not contain a halogen atom means that the halogen content in the block copolymer is 100 ppm or less. Halogen content is calculated | required by a combustion ion chromatograph.

In the present invention, the block copolymer does not contain an unsaturated bond in the main chain. The main chain is, for example, a polymer based on addition polymerization of a C = C bond, and a chain formed by a unit-(CR ₂ -CR ₂ )-(each R is independently a hydrogen atom or a bond with a side chain). to be. Therefore, for example, copolymers having units based on 1,4-addition polymerization of conjugated dienes such as isoprene and butadiene are not included in the copolymers containing no unsaturated bond in the main chain in the present invention. Do not.

The block copolymer which does not contain an unsaturated bond in a main chain can be regarded that the iodine number is 10 mg / 100 mg or less. Iodine number can be calculated | required in accordance with JIS K 0070 (1992).

The two segments of the block copolymer used in the present invention can be composed of various components as long as they do not contain halogen atoms and do not contain unsaturated bonds in the main chain. Especially, in order for the electrode to have electrolyte solution impregnation and electrolyte retention, and the dispersibility of an electrode active material improves, one type of segment is based on the electrolyte solution containing ethylene carbonate and diethyl carbonate. It is preferable that the compatibility with respect to the solvent is not shown and that other segments do not exhibit compatibility with the electrolyte solution. In the following description, the former of the two kinds of segments is referred to as segment A, and the latter is referred to as segment B for convenience.

The fact that a segment exhibits compatibility with the electrolyte indicates that the segment exhibits a predetermined or more expansion in the electrolyte, and can be determined by the degree of swelling of the segment with respect to the electrolyte. Here, showing compatibility indicates that the swelling degree of the segment with respect to the said electrolyte solution is 500% or more, or it melt | dissolves in the said electrolyte solution.

On the other hand, that a segment does not show compatibility with the said electrolyte solution indicates that the expansion which the segment shows in the said electrolyte solution is fixed or less, and the swelling degree of the segment with respect to electrolyte solution is 0% or more and 300% or less.

(Swelling degree)

In the present invention, the swelling degree of each segment is measured by the following method.

The polymer composed of the constituents of the segment A and the polymer composed of the constituents of the segment B are each molded into a film having a thickness of about 0.1 mm, and this is cut out to about 2 cm in width and weighed (weight before immersion). Then, it is immersed for 72 hours in the said electrolyte solution of temperature 60 degreeC. The immersed film is pulled up, the weight immediately after wiping off the electrolyte solution (weight after immersion) is measured, and the value of (after immersion weight) / (weight before immersion) x 100 (%) is defined as the swelling degree.

As said electrolyte solution, the mixture which mixes ethylene carbonate (EC) and diethyl carbonate (DEC) by EC: DEC = 1: 2 (volume ratio, EC is the volume at 40 degreeC, DEC is the volume at 20 degreeC) A solution in which LiPF ₆ was dissolved in a solvent at a concentration of 1 mol / liter is used.

When a block copolymer has the said structure, in an electrode active material slurry mentioned later, an electrode active material and the electrically conductive agent mentioned later can be disperse | distributed highly in a solvent. Furthermore, when the electrode containing the block copolymer which has the said structure is used inside a battery, the electrode has a high electrolyte retention property for a long time, and also the elution of a metal ion and an oligomer component from an electrode is suppressed, and the electrode Secondary batteries having high exhibit high long-term cycle characteristics. In addition, since the block copolymer forms an island-in-sea structure within the electrode and has a moderate swelling property to the electrolyte, the electrode exhibits high lithium conductivity, and the secondary battery having the electrode exhibits high output characteristics.

The block copolymer used in the present invention may be an AB block structure composed of only the above-mentioned segment A and segment B (where the AB block structure is a structure selected from the group consisting of structures of AB type, ABA type, and BAB type). May be sufficient as it, and the structure containing another arbitrary component may be sufficient. When it contains another arbitrary component, such arbitrary component may be coordinated to the terminal of the AB block structure, may be coordinated in the AB block structure, or any may be sufficient as it.

Especially, it is preferable at the point that an electrode has high electrolyte solution impregnation and electrolyte retention, and the secondary battery which has the electrode shows high long-term cycling characteristics especially that a terminal structure is a component which shows compatibility with electrolyte solution.

(Segment A)

It is preferable that the segment A contains the monomer component which has a solubility parameter of 8.0 or more and less than 11 (unit: (cal / cm <3>) ^1/2 ), and / or the monomer component which has a hydrophilic group. By including such a monomer component, the swelling degree with respect to the electrolyte solution of the segment A can be controlled by a composition, and it can be set as the segment which shows compatibility with electrolyte solution.

In this application, the wording of a "monomer" or a "monomer component" is interpreted as the monomer which comprises a monomer composition or the polymerization unit based on the monomer which comprises a polymer according to the context.

As a monomer whose said solubility parameter is 8.0 or more and less than 11, Alkenes, such as ethylene and propylene; Alkyl groups in ester groups, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and pentyl methacrylate; Alkyl methacrylate having 1 to 5 carbon atoms; alkyl acrylate having 1 to 5 carbon atoms in alkyl groups in ester groups such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and pentyl acrylate; And vinyl esters such as vinyl, vinyl propionate, vinyl butyrate and vinyl benzoate. Among these, since the compatibility with electrolyte solution is high and it is difficult to produce crosslinking aggregation by a polymer in dispersion of a small particle size, the alkyl group in the alkyl group of 1-5 carbon atoms or the alkyl group in an ester group has 1 carbon number. Methacrylic acid alkyl ester of? 5 is more preferable.

As alkyl acrylate or alkyl methacrylate, carbon number of the alkyl group in ester groups, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, and pentyl acrylate, is 1 ? 5 alkyl acrylates; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, and the like. The methacrylic acid alkyl ester whose carbon number of the alkyl group in the ester group of 1-5 is mentioned.

The monomer component whose solubility parameter (SP) in segment A is 8.0 or more and less than 11, when segment A which shows compatibility with electrolyte solution contains the unit of the monomer component whose solubility parameter (SP) is 8.0 or more and less than 11. The content of is preferably 30% by mass or more, more preferably 50 to 90% by mass with respect to 100% by mass of the total amount of the monomers to be used. Content of the monomer component whose solubility parameter (SP) in segment A is 8.0 or more and less than 11 can be controlled by the monomer injection ratio at the time of block polymer manufacture. When the solubility parameter (SP) is in the range of 8.0 or more and less than 11, the content of the monomer component is in the appropriate range, thereby exhibiting compatibility with the electrolytic solution and not dissolving, without causing elution inside the battery, thereby exhibiting high long-term cycle characteristics.

The solubility parameter of a polymer can be calculated | required according to the method described in the Polymer Handbook, but the thing which is not described in this publication can be calculated | required according to the "molecular attraction constant method" proposed by Small. In this method, compound property values of the groups (atomic groups) that make up the molecule, that is, from the statistics and molecular volume of the molecular attraction constants (G) according to the following equation for obtaining the SP values (δ) (cal / ㎤) 1/2 Way.

δ = ∑G / V = d∑G / M

∑G ： Total molecular attraction constant G

V ： Cost

M ： Molecular Weight

d ： weight

Examples of the monomer component having a hydrophilic group include a monomer having a -COOH group (carboxylic acid group), a monomer having a -OH group (hydroxyl group), a monomer having a -SO ₃ H group (sulfonic acid group), and a -PO ₃ H ₂ group. The monomer which has a monomer, a -PO (OH) (OR) group (R represents a hydrocarbon group), and the monomer which has a lower polyoxyalkylene group are mentioned.

As a monomer which has a carboxylic acid group, monocarboxylic acid, its derivative (s), dicarboxylic acid, its acid anhydride, these derivatives, etc. are mentioned. Acrylic acid, methacrylic acid, crotonic acid, etc. are mentioned as monocarboxylic acid. As a monocarboxylic acid derivative, 2-ethylacrylic acid, isocrotonic acid, (alpha)-acetoxy acrylic acid, (beta) -trans- aryloxyacrylic acid, (beta)-diamino acrylic acid, etc. are mentioned. Examples of the dicarboxylic acid include maleic acid, fumaric acid and itaconic acid. Examples of the acid anhydride of the dicarboxylic acid include maleic anhydride, acrylic acid anhydride, methyl maleic anhydride, and dimethyl maleic anhydride. Examples of the dicarboxylic acid derivatives include maleic esters such as methyl maleic acid such as methyl maleic acid, dimethyl maleic acid and phenyl maleic acid, diphenyl maleic acid, nonyl maleic acid, decyl maleic acid, dodecyl maleic acid and octadecyl maleic acid. Can be mentioned.

As a monomer which has a hydroxyl group, Ethylenic unsaturated alcohols, such as (meth) allyl alcohol, 3-butene-1-ol, and 5-hexene-1-ol; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate. , Methacrylic acid-2-hydroxyethyl, methacrylic acid-2-hydroxypropyl, maleic acid-di-2-hydroxyethyl, maleic acid di-4-hydroxybutyl, itaconic acid di-2-hydroxypropyl Alkanol esters of ethylenically unsaturated carboxylic acids such as; general formula CH ₂ = CR ¹ -COO- (C _n H _2n O) _m -H (m is an integer of 2 to 9, n is an integer of 2 to 4) , R ¹ represents hydrogen or a methyl group); esters of polyalkylene glycol and (meth) acrylic acid; 2-hydroxyethyl-2 '-(meth) acryloyloxyphthalate, 2-hydroxyethyl-2 Mono (meth) acrylic acid esters of dihydroxy esters of dicarboxylic acids such as'-(meth) acryloyloxysuccinate; 2-hydroxy Vinyl ethers such as cyethyl vinyl ether and 2-hydroxypropyl vinyl ether; (meth) allyl-2-hydroxyethyl ether, (meth) allyl-2-hydroxypropyl ether, (meth) allyl-3-hydroxy Hydroxypropyl ether, (meth) allyl-2-hydroxybutyl ether, (meth) allyl-3-hydroxybutyl ether, (meth) allyl-4-hydroxybutyl ether, (meth) allyl-6-hydroxyhexyl Mono (meth) allyl ethers of alkylene glycols such as ether; polyoxyalkylene glycol (meth) monoallyl ethers such as diethylene glycol mono (meth) allyl ether and dipropylene glycol mono (meth) allyl ether; glycerin Mono (meth) allyl ethers of hydroxy substituents of (poly) alkylene glycols such as mono (meth) allyl ethers; mono (meth) allyl ethers of polyhydric phenols such as eugenol and iso igenol; Allyl-2-hydroxyethylthioether, (meth) allyl-2-hydroxy (Meth) allylthio ethers of alkylene glycols, such as propyl propyl ether, etc. are mentioned.

Moreover, as a monomer which has a sulfonic acid group, vinylsulfonic acid, methylvinylsulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, ethyl (meth) acrylic acid-2-sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 3-aryloxy 2-hydroxypropanesulfonic acid etc. are mentioned.

-PO ₃ H ₂ group and / or -PO (OH) (OR) group of the monomer having the (R represents a hydrocarbon group) is phosphate-2- (meth) acryloyloxyethyl phosphate, methyl-2- ( (Meth) acryloyloxyethyl, ethyl phosphate ((meth) acryloyloxyethyl, etc. are mentioned.

As a monomer containing a lower polyoxyalkylene group containing group, poly (alkylene oxide), such as poly (ethylene oxide), etc. are mentioned.

As segment A which shows compatibility with electrolyte solution, when it contains the unit of the monomer component which has the said hydrophilic group, among these monomers which have a hydrophilic group, from a viewpoint of further improving the dispersibility of an electrode active material and the electrically conductive agent mentioned later, Preference is given to monomers having carboxylic acid groups.

When segment A which shows compatibility with electrolyte solution contains the unit of the monomer component which has the said hydrophilic group, content of the monomer which has a hydrophilic group in segment A becomes like this with respect to 100 mass% of monomer total amounts to use preferably. Is 0.5-40 mass%, More preferably, it is the range of 3-20 mass%. Content of the monomer which has a hydrophilic group in segment A can be controlled by the monomer injection ratio at the time of block polymer manufacture. When content of the monomer which has the hydrophilic group of segment A exists in a predetermined range, swelling property with respect to appropriate electrolyte solution is shown, and dissolution inside a battery does not occur, either.

The segment A may have one type in these monomer components independently, or may have it in combination of 2 or more types. Segment A may further contain the monomer copolymerizable with these monomers mentioned later.

(Segment B)

It is preferable that segment B contains the unit of the monomer component which has a solubility parameter less than 8.0 or 11 or more, and / or a hydrophobic part. By including such a monomer component, the swelling degree with respect to the electrolyte solution of the segment B can be controlled by a composition, and it can be set as the segment which does not show compatibility with electrolyte solution. In order to control swelling degree by bridge | crosslinking and to show the compatibility with respect to electrolyte solution, it is preferable to include the unit of the monomer component which has a crosslinkable group mentioned later.

As a monomer component whose solubility parameter is less than 8.0 or 11 or more, (alpha), (beta)-unsaturated nitrile compounds, such as acrylonitrile and methacrylonitrile, etc. are mentioned.

When segment B contains the unit of the monomer component whose solubility parameter SP is less than 8.0 or 11 or more, content of the monomer component whose solubility parameter in segment B is less than 8.0 or 11 or more is 100 whole monomers to use. Preferably it is 30 mass% or more and 100 mass% or less with respect to mass%, More preferably, it is the range of 50 mass% or more and 100 mass% or less. Content of the monomer component whose solubility parameter (SP) in segment B is less than 8.0 or 11 or more can be controlled by the monomer injection ratio at the time of block copolymer manufacture. When the content ratio of the monomer component whose solubility parameter (SP) is less than 8.0 and 11 or more in segment B exists in the said range, it exhibits higher electrolyte resistance and long-term cycling characteristics.

As a monomer component which has a hydrophobic part, Styrene-type monomers, such as styrene, (alpha)-styrene, vinyltoluene, t-butyl styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, (alpha) -methylstyrene, divinylbenzene; An alkyl group having 6 or more carbon atoms in an ester group such as acrylic acid-heptyl, acrylic acid-octyl, acrylic acid-2-ethylhexyl, acrylic acid-nonyl, acrylic acid-decyl, acrylic acid-lauryl, acrylic acid-n-tetradecyl, and acrylic acid-stearyl Alkyl acrylate; methacrylic acid-hexyl, methacrylic acid-heptyl, methacrylic acid-octyl, methacrylic acid-2-ethylhexyl, methacrylic acid-nonyl, methacrylic acid-decyl, methacrylic acid-lauryl, And methacrylic acid alkyl esters having 6 or more carbon atoms of alkyl groups in ester groups such as methacrylic acid-n-tetradecyl and methacrylic acid-stearyl.

In the present invention, as a monomer component constituting segment B which does not exhibit compatibility with the electrolyte solution, since it has low compatibility with the electrolyte solution, 2-ethylhexyl acrylate, nonyl acrylate, acrylic acid-decyl, and acrylic acid-la. Acrylate alkyl esters having 9 or more carbon atoms of alkyl groups such as uryl, acrylic acid-n-tetradecyl and acrylic acid-stearyl, methacrylic acid-2-ethylhexyl, methacrylic acid-nonyl, methacrylic acid-decyl and methacrylic acid- Methacrylic acid alkyl ester (alpha), (beta)-unsaturated nitrile compound and styrene-based monomer which have 9 or more carbon atoms of alkyl groups in ester groups, such as lauryl, methacrylic acid-n- tetradecyl, and methacrylic acid-stearyl, are preferable, and electrolyte solution Since the swelling property is not exhibited at all, the α, β-unsaturated nitrile compound and the styrene monomer are more preferable, and the styrene monomer is most preferred.

When the segment B contains the unit of the monomer component which has a hydrophobic part, content of the monomer component which has a hydrophobic part in segment B becomes like this. Preferably it is 10 mass% or more and 100 mass mass with respect to 100 mass% of monomer total amounts to use. % Or less, More preferably, they are 20 mass% or more and 100 mass% or less. Content of the monomer component which has a hydrophobic part in segment B can be controlled by the monomer injection ratio at the time of block polymer manufacture. When content of the monomer component which has a hydrophobic part in segment B exists in the said range, higher electrolyte resistance and long-term cycle characteristic are shown.

When the segment B contains the unit of the monomer component which has a crosslinkable group mentioned later, content of the monomer component which has a crosslinkable group in segment B becomes like this. Preferably it is 0.1 mass with respect to 100 mass% of monomer total amounts to use. % Or more and 10 mass% or less, More preferably, they are 0.1 mass% or more and 5 mass% or less. Content of the monomer component which has a crosslinkable group in segment B can be controlled by the monomer injection ratio at the time of block polymer manufacture. When content of the monomer component which has a crosslinkable group in segment B exists in the said range, higher electrolyte resistance and long-term cycling characteristics are shown.

Segment B may have one type of these monomer components alone, or may have two or more types in combination. The segment B may also contain the monomer copolymerizable with these monomers mentioned later.

In this invention, it is preferable that a block copolymer contains the segment of the soft polymer of 15 degrees C or less of glass transition temperature. "The block polymer contains the segment of the soft polymer of 15 degrees C or less of glass transition temperature" means that the block polymer of this invention contains the segment which comprises the soft polymer whose glass transition temperature is 15 degrees C or less. Specifically, at least one of the segment A and the segment B is preferably the same segment as the segment constituting the soft polymer having a glass transition temperature of 15 ° C. or lower, because an electrode having high flexibility is obtained.

Especially, when segment A shows compatibility with electrolyte solution, and segment B does not show compatibility with electrolyte solution, it should be said that segment A is the same segment as the segment which comprises the soft polymer of 15 degrees C or less of glass transition temperature. Preferably, it is more preferably the same segment as the segment constituting the soft polymer having a glass transition temperature of −5 ° C. or lower, and particularly preferably the same segment as the segment constituting the soft polymer having a glass transition temperature of −40 ° C. or lower. . Although the minimum of the said glass transition temperature is not specifically limited, It can be -40 degreeC or more. Since segment A is the same segment as the segment which comprises the soft polymer whose glass transition temperature exists in the said range, since the mobility of segment A increases in the state which segment B in the block copolymer adsorb | sucked to the active material surface, at low temperature, The lithium water solubility is improved.

In addition, the glass transition temperature of a segment can be prepared by further combining the combination of the monomer illustrated above, and the copolymerizable monomer mentioned later.

The ratio of the segment A and the segment B in the block copolymer has a long-term cycle characteristic and high output characteristics by controlling the swelling degree of the block copolymer to the electrolyte within a predetermined range, and according to its composition, crosslinking degree, etc. Although different, but when it does not have copolymerization components other than segment A and segment B, the ratio of segment A and segment B is 10: 90-90: 10 (mass ratio), More preferably, it is 30: 70-70: 30 ( Mass ratio).

As a combination of the segment A and the segment B in a block polymer, it is preferable to combine the preferable thing of the segment A mentioned above, and the preferable thing of the segment B. Among these, as the segment A, a methacrylic acid alkyl ester having 1 to 5 carbon atoms of an alkyl group in an ester group such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate and pentyl methacrylate; Monomers, derivatives thereof, dicarboxylic acids, acid anhydrides, and monomers having carboxylic acid groups such as derivatives thereof include, as the segment B, styrene, α-styrene, vinyltoluene, t-butylstyrene, and vinyl. Styrene monomers such as benzoic acid, methyl vinyl benzoate, vinyl naphthalene, α-methylstyrene, divinylbenzene; acrylic acid-hexyl, acrylic acid-heptyl, acrylic acid-octyl, acrylic acid-2-ethylhexyl, acrylic acid-nonyl, acrylic acid-decyl, Combinations of alkyl acrylates having 6 or more carbon atoms in the alkyl groups such as acrylic acid-lauryl, acrylic acid-n-tetradecyl, and acrylic acid stearyl are preferred. , As a segment A, roneun carbon atoms in the alkyl group of the ester group 1? 5, the methacrylic acid alkyl ester, the segment B, is the most preferred in combination with excellent dispersibility, high rate characteristics, cycle characteristics of the styrene-point.

The swelling degree with respect to the electrolyte solution of a block copolymer tends to become small, so that molecular weight is large, and it becomes large, so that molecular weight is small. When molecular weight is too small, there exists a tendency for the solubility to electrolyte solution to occur easily. Therefore, although the range of the weight average molecular weight of a block polymer for making it preferable swelling degree changes with the structure, the crosslinking degree, etc., for example, when it does not have copolymerization components other than segment A and segment B, it is tetrahydrofuran (THF ) Is 1,000 to 500,000, more preferably 5,000 to 100,000 in terms of standard polystyrene measured by gel permeation chromatography using as a developing solvent. When the weight average molecular weight of a block polymer exists in the said range, the adsorption stability of a polymer with respect to an active material is high, crosslinking aggregation by a polymer does not occur, and it shows the outstanding dispersibility. Moreover, it is preferable that the molecular weight distribution of the block copolymer represented by ratio Mw / Mn of weight average molecular weight Mw and number average molecular weight Mn is less than 2.0, More preferably, it is 1.8 or less, Especially preferably, it is 1.5 or less. When the molecular weight distribution of the block copolymer is in the above range, the microphase separation structure becomes uniform, and stable strength is obtained. The lower limit of the molecular weight distribution is not particularly limited, but may be 1.01 or more.

Swelling degree with respect to the electrolyte solution of a block copolymer can be controlled by crosslinking degree. The degree of swelling of the electrolyte solution tends to decrease as the degree of crosslinking increases. When the range of preferable crosslinking degree is immersed in polar solvents, such as tetrahydrofuran for 24 hours, the crosslinking degree of the grade which melt | dissolves or swells at 400% or more is preferable.

As a bridge | crosslinking method of a block copolymer, the method of bridge | crosslinking by heating or energy ray irradiation is mentioned. By crosslinking and using the crosslinkable block copolymer by heating or energy ray irradiation, the degree of crosslinking can be adjusted by heating conditions or irradiation conditions (strength or the like) of energy ray irradiation. In addition, since the degree of swelling tends to decrease as the degree of crosslinking is higher, the degree of swelling can be adjusted by changing the degree of crosslinking.

As a method of making a block copolymer crosslinkable by heating or energy-beam irradiation, the method of introducing a crosslinkable group in a block copolymer, or the method of using a crosslinking agent together is mentioned.

As a method of introducing a crosslinkable group into the said block copolymer, the method of introduce | transducing a photocrosslinkable crosslinkable group into a block copolymer, and the method of introduce | transducing a heat crosslinkable crosslinkable group can be mentioned. Among these, the method of introducing a thermally crosslinkable crosslinkable group into the block copolymer is capable of crosslinking the electrode by suppressing dissolution in the electrolyte solution by subjecting the electrode to heat treatment after electrode formation, thereby being robust and flexible. It is preferable because an electrode is obtained. In the case where a heat crosslinkable crosslinkable group is introduced into the block copolymer, the heat crosslinkable crosslinkable group is selected from the group consisting of an epoxy group, a hydroxyl group, an N-methylolamide group, an oxetanyl group, and an oxazoline group. At least 1 type is preferable and an epoxy group is more preferable at the point which is easy to adjust crosslinking and a crosslinking density.

As a monomer containing an epoxy group, the monomer containing a carbon-carbon double bond and an epoxy group is mentioned.

As a monomer containing a carbon-carbon double bond and an epoxy group, For example, unsaturated glycy, such as vinylglycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, o-allylphenyl glycidyl ether, etc. Dimethyl ether, such as butadiene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene and 1,2-epoxy-5,9-cyclododecadiene; Monoepoxides; alkenylepoxides such as 3,4-epoxy-1-butene, 1,2-epoxy-5-hexene and 1,2-epoxy-9-decene; glycidyl acrylate, glycidyl meta Acrylate, glycidyl crotonate, glycidyl-4-heptenoate, glycidyl sorbate, glycidyl linoleate, glycidyl-4-methyl-3-pentenoate, 3-cyclohexene Glycidyl esters of unsaturated carboxylic acids such as glycidyl ester of carboxylic acid and glycidyl ester of 4-methyl-3-cyclohexene carboxylic acid. The.

As a monomer containing an N-methylolamide group, (meth) acrylamide which has methylol groups, such as N-methylol (meth) acrylamide, is mentioned.

As a monomer containing an oxetanyl group, 3-((meth) acryloyloxymethyl) oxetane, 3-((meth) acryloyloxymethyl) -2-trifluoromethyloxetane, 3- ( (Meth) acryloyloxymethyl) -2-phenyloxetane, 2-((meth) acryloyloxymethyl) oxetane, 2-((meth) acryloyloxymethyl) -4-trifluoromethyl Oxetane etc. are mentioned.

Examples of the monomer containing an oxazoline group include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-isopropenyl- 2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, etc. Can be mentioned.

The content rate of the thermally crosslinkable crosslinkable group in the block copolymer is a monomer amount containing a thermally crosslinkable crosslinkable group at the time of polymerization, and is preferably 0.1 to 10 mass%, more preferably to 100 mass% of the total monomer amount. Is in the range of 0.1 to 5 mass%. The content rate of the heat crosslinkable crosslinkable group in a block copolymer can be controlled by the monomer injection ratio at the time of manufacturing a block copolymer. By the content rate of the heat crosslinkable crosslinkable group in a block copolymer being in the said range, elution to electrolyte solution can be suppressed and it can exhibit the outstanding electrode strength and long-term cycling characteristics.

The thermally crosslinkable crosslinkable group may be introduced into the block copolymer by copolymerizing a monomer containing a thermally crosslinkable crosslinkable group in addition to the monomers described above and / or any monomer copolymerizable with these monomers in addition to the monomers described above. Can be.

The block copolymer used for this invention may contain the monomer copolymerizable with these other than the monomer component mentioned above. As a monomer copolymerizable with these, Carboxylic acid ester which has 2 or more carbon-carbon double bonds, such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylol propane triacrylate; Methyl vinyl ether Vinyl ethers such as ethyl vinyl ether and butyl vinyl ether; vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone, and isopropenyl vinyl ketone; N-vinylpyrrolidone, vinyl pyridine, Heterocyclic containing vinyl compounds, such as vinylimidazole; Amide system monomers, such as acrylamide and N-methylol acrylamide, are mentioned. By copolymerizing these monomers by an appropriate method, the block polymer of the said structure is obtained.

The block copolymer used for this invention is not specifically limited about the polymerization method, if the block copolymer which has the segment A and the segment B is obtained, 1) Monomer A for constructing segment A by chain polymerization, Sequential growth method of monomer B for constituting segment B, 2) Coupling method of polymer A corresponding to segment A and polymer B corresponding to segment B, each of which distribution is regulated, or polyaddition using terminal functional groups It is synthesize | combined by the chain polymerization method etc. which made polymer A correspond to the segment A which has a legal method and 3) terminal functional groups as a macro initiator.

In the method of said 1), a block copolymer can be obtained by superposing | polymerizing monomer A by a living polymerization method and then adding monomer and superposing | polymerizing, without stopping the growth terminal of the obtained polymer.

In the method of said 2), monomer A and monomer B are respectively synthesize | combined separately by the living polymerization method, and a functional group is introduce | transduced into each terminal so that polymer A and polymer B may couple | bond preferably by the terminal to react. Thereafter, the block copolymer can be obtained by mixing the A and B with the coupling reaction and polyaddition. For example, the method of interfacial polycondensation or solution polycondensation of an acid chloride and an amine, the method of polycondensing the polyamide of an amine terminal, and the polyamide of a carboxylic acid terminal in a molten state, etc. are mentioned.

In the method of said 3), after polymerizing monomer A by a living polymerization method, a functional group is introduce | transduced into a living terminal and polymer A which has a terminal functional group is obtained. A block copolymer can be obtained by introducing a radical initiator into the obtained polymer A by end group reaction and chain-polymerizing with monomer B as a macro initiator. For example, when it has an OH group in a polymer terminal, the method of NCO-ization with excess diisocyanate, couple | bonding t-butylhydroperoxide to the terminal, and then radically polymerizing is mentioned.

The living polymerization method includes various polymerization methods such as living anion polymerization, living cation polymerization, living coordination polymerization, and living radical polymerization. By using such a polymerization method, it is possible to polymerize various vinyl monomers. Especially, living radical polymerization is preferable at the point of the molecular weight and structure control of a block copolymer, and the point which can copolymerize the monomer which has a crosslinkable functional group.

In a narrow sense, living polymerization refers to polymerization in which the terminal always has an active activity, and generally includes pseudo living polymerization in which the terminal is inactivated and the activated one is in an equilibrium state. Living radical polymerization in the present invention is radical polymerization in which the polymerization terminal is activated and inactivated is maintained in an equilibrium state, and various groups have been actively researched in recent years.

Examples include the use of chain transfer agents such as polysulfide, the use of cobalt porphyrin complexes (Journal of American Chemical Society, 1994, Vol. 116, p. 7943) or radical scavengers such as nitroxide compounds. (Macromolecules, 1994, Vol. 27, p. 7228), Inipata polymerization of radical cleavage by photoirradiation of dithiocarbamate by Otsu et al. (Macromol. Chem. Rapid Commun., 3, 133 (1982)), organic Reversible addition desorption chain transfer using a compound having an atom transfer radical polymerization (ATRP), a thiocarbonylthio (thioester) structure using a halide or the like as a catalyst, as a chain transfer agent (Reversible Addition-Fragmentation Chain Transfer: RAFT) polymerization and the like. In the present invention, there is no particular restriction as to which of these methods is used, but it is preferable to use a radical supplement or reversible addition tally chain transfer polymerization for ease of control.

In the case of using a radical supplement as living polymerization, a stable nitrooxy radical compound is used as the radical supplement. It does not specifically limit as said stable nitoxy radical compound, A well-known stable free radical agent is mentioned, It is mentioned from cyclic hydroxyamines, such as 2,2,5,5-substituted-1-pyrrolidinyl oxy radicals. Nitoxy free radicals are preferable. As a substituent, C4 or less alkyl groups, such as a methyl group and an ethyl group, are suitable. Although it does not limit as a specific nitrooxy free radical compound, 2,2,6,6- tetramethyl-1- piperidinyl oxy radical (TEMPO), 2,2,6,6- tetraethyl-1- pipepe Ridinyloxy radicals, 2,2,6,6-tetramethyl-4-oxo-1-piperidinyloxy radicals, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy radicals, 1,1 And 3,3-tetramethyl-2-isoindolinyloxy radicals, and N, N-di-t-butylamine oxy radicals. Among them, 2,2,6,6, -tetramethyl-1-piperidinyloxy and 4-oxo-2,2,6,6, -tetramethyl-1-piperidinyloxy are preferable. These may be used independently and may be used together 2 or more types.

When using the said stable nitrooxy radical compound, a radical generator is used normally. The radical generator is not particularly limited as long as it generates radicals at a polymerization temperature, and a general thermal decomposition polymerization initiator can be used, for example, azobisisobutyronitrile (AIBN), azobisisobutyric acid ester, Azo compounds, such as hyponitrous acid ester; Benzoyl peroxide (BPO), lauroyl peroxide, dicumyl peroxide, dibenzoyl peroxide, etc. are mentioned. These may be used independently and may be used together 2 or more types.

Instead of using a stable nitoxy radical compound and a radical generator together, you may use an alkoxyamine compound as an initiator. When using an alkoxyamine compound as an initiator, a terminal functional group can be introduce | transduced by using the alkoxyamine which has a functional group in an alkoxy group.

When using the said stable nitoxy radical compound or the alkoxyamine compound, it is common for superposition | polymerization temperature to superpose | polymerize at about 50-170 degreeC. As a preferable temperature range, it is 70-160 degreeC. Although reaction pressure is normally performed at normal pressure, it can also carry out by pressurizing.

In the case of using the said stable nitrooxy radical compound, as a method of introducing a functional group into the terminal of the polymerized vinyl type copolymer, for example, using a chain transfer agent or a terminator which has a target functional group in a molecule | numerator The method etc. are mentioned. It does not specifically limit as a chain transfer agent and a terminator which has the said functional group in a molecule | numerator, For example, a hydroxyl group is introduce | transduced by mercaptoethanol, mercaptopropanol, mercapto butanol, 2,2'- dithioethanol, etc., 2- A carboxyl group is introduced by mercaptoacetic acid, 2-mercaptopropionic acid, dithioglycolic acid, 3,3'-dithiopropionic acid, 2,2'-dithiobenzoic acid, or the like, and 3-mercaptopropylmethyldimethoxysilane or the like. Silyl groups are introduced.

In the case of using reversible addition tally chain transfer polymerization (RAFT polymerization) as living polymerization, as a chain transfer agent (also serves as an initiator), such as dithioester, trithiocarbamate, xanthate or dithiocarbamate The polymerization is carried out using a sulfur compound as an initiator (for example, WO98 / 01478 A1 and WO99 / 31144 A1 and the like). These may be used independently and may be used together 2 or more types.

When using RAFT polymerization as a living polymerization, it is preferable to use an additional radical initiator for polymerization, especially an initiator further comprising an azo or peroxo initiator which decomposes to heat to generate radicals. For example, azo compounds, such as azobisisobutyronitrile (AIBN), azobisisobutyric acid ester, and hyponitride ester; benzoyl peroxide (BPO), lauroyl peroxide, dicumyl peroxide, dibenzoyl peroxide, etc. are mentioned. Can be. These may be used independently and may be used together 2 or more types.

Living polymerization in the present invention can be carried out by a solvent polymerization (block polymerization), solution polymerization in an organic solvent (for example toluene), emulsion polymerization or suspension polymerization. Each step of the polymerization method can be carried out in the same reactor by the "batch" method (that is, discontinuous method), or in each reactor by the semi-continuous or continuous method.

When carrying out solution polymerization, although the following solvent is mentioned as a solvent used, it is not limited to those. For example, hydrocarbon solvents such as hexane and octane; ester solvents such as ethyl acetate and n-butyl acetate; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; alcohols such as methanol, ethanol and isopropanol Solvents; ether solvents such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether; amide solvents such as dimethylformamide and dimethylacetamide; aromatic petroleum solvents such as toluene, xylene, benzene, etc. Can be mentioned. These may be used independently and may be used in combination of plurality. The type and amount of the solvent to be used are appropriate so that the solubility of the monomer to be used, the solubility of the polymer to be obtained, and the sufficient reaction rate to achieve an appropriate polymerization initiator concentration and monomer concentration, the solubility of the sulfur compound, the influence on the human body and the environment, availability and price What is necessary is just to consider and etc., and it is not specifically limited. Especially, toluene, dimethylformamide, tetrahydrofuran, and acetone are preferable from a viewpoint of solubility, availability, and price, and toluene and dimethylformamide are more preferable.

When emulsion-polymerizing, although the following emulsifiers are mentioned as an emulsifier used, it is not limited to them. For example, fatty acid soap, rosin acid soap, sodium naphthalene sulfonate formalin condensate, sodium alkyl sulfonate, sodium alkylbenzene sulfonate, sodium alkyl sulfate, ammonium alkyl sulfate, alkyl triethanolamine, sodium dialkyl sulfosuccinate, alkyl diphenyl ether di Anionic surfactants such as sodium sulfonate, sodium polyoxyethylene alkyl ether sulfate and sodium polyoxyethylene alkyl phenyl ether sulfate; polyoxyethylene alkyl ether, polyoxyethylene higher alcohol ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, Nonionic surfactants such as polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, alkylalkanolamides; and cationic surfactants such as alkyltrimethylammonium chlorides. . These emulsifiers may be used independently, and may be used in combination of plurality. As needed, you may add the dispersing agent of suspension polymerization mentioned later. Although the usage-amount of an emulsifier is not specifically limited, 0.1-20 mass parts is preferable with respect to 100 mass parts of monomers in the point which emulsion state is favorable and superposition | polymerization advances smoothly. Among these emulsifiers, anionic surfactants and nonionic surfactants are preferable from the viewpoint of stability of the emulsified state.

In the case of suspension polymerization, any of the dispersants usually used may be used as the dispersant used. For example, the following dispersing agents are mentioned, It is not limited to them. Examples thereof include partially saponified polyvinyl acetate, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, gelatin, polyalkylene oxide and the like. These may be used independently and may be used in combination of plurality. As needed, you may use together the emulsifier used at the time of the said emulsion polymerization. Although the usage-amount of a dispersing agent is not specifically limited, 0.1-20 weight part is preferable with respect to 100 weight part of monomers used in that superposition | polymerization advances smoothly.

It is preferable that the block copolymer used for this invention is obtained through the particulate metal removal process which removes the particulate metal contained in a polymer solution or a polymer dispersion liquid in the manufacturing process of a block copolymer. By content of the particulate metal component contained in a polymer solution or a polymer dispersion liquid being 10 ppm or less, time-lapse metal ion bridge | crosslinking between the polymer in the electrode active material slurry mentioned later can be prevented, and a viscosity rise can be prevented. Moreover, there is little possibility of the increase of the self discharge by the internal short circuit of a secondary battery or melt | dissolution and precipitation at the time of charge, and the cycling characteristics and safety of a battery improve.

The method of removing a particulate metal component from the polymer solution or polymer dispersion liquid in the said particulate metal removal process is not specifically limited, For example, the method of removing by filtration by a filtration filter, and the method of removing by a vibrating sieve. The method of removing by centrifugation, the method of removing by magnetic force, etc. are mentioned. Especially, since the removal object is a metal component, the method of removing by magnetic force is preferable. The method of removing by magnetic force is not particularly limited as long as it is a method capable of removing a metal component. However, in consideration of productivity and removal efficiency, the method is preferably performed by arranging a magnetic filter in a production line of a block copolymer.

The content ratio of the block copolymer in the secondary battery electrode is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass with respect to 100 parts by mass of the active material. When the content ratio of the block copolymer in the electrode for secondary batteries is in the said range, while binding property with respect to active materials and an electrical power collector is excellent, and flexibility is maintained, the movement of Li is not inhibited and resistance does not increase. .

(Current collector)

The current collector used for the electrode for secondary batteries of the present invention is not particularly limited as long as it is an electrically conductive and electrochemically durable material. For example, iron, copper, aluminum, nickel, Metal materials, such as stainless steel, titanium, tantalum, gold, and platinum, are preferable. Especially, aluminum is especially preferable for the positive electrode of a lithium ion secondary battery. Although the shape of an electrical power collector is not specifically limited, It is preferable that it is a sheet form with a thickness of about 0.001-0.5 mm. In order that a collector may raise the adhesive strength of an electrode active material layer, it is preferable to use it, roughening previously. Examples of the roughening method include mechanical roughening, electrolytic roughening, and chemical roughening. In the mechanical polishing method, a polishing cloth on which abrasive particles are fixed, a wire brush provided with a grindstone, an emery buff, a steel wire, or the like is used. Moreover, in order to improve the adhesive strength and electroconductivity of an electrode active material layer, you may form an intermediate | middle layer in the electrical power collector surface.

(Other Containing Ingredients)

In addition to the above components, the secondary battery electrode of the present invention may optionally contain a conductive agent, a reinforcing agent, a dispersant, a leveling agent, an antioxidant, a thickener, an electrolyte solution additive having a function such as suppression of electrolyte solution decomposition, a binder other than a block copolymer, and the like. The component of may be contained and may be contained in the electrode active material slurry mentioned later. These are not particularly limited as long as they do not affect the battery reaction.

As the conductive agent, conductive carbon such as acetylene black, Ketjen black, carbon black, graphite, vapor-grown carbon fiber, carbon nanotube and the like can be used. Carbon powder, such as graphite, fiber, foil of various metals, etc. are mentioned. By using an electroconductivity imparting material, the electrical contact of electrode active materials can be improved, and discharge load characteristics can be improved especially when using for a lithium ion secondary battery. As the reinforcing material, various inorganic and organic spherical, plate-like, rod-like or fibrous fillers can be used. By using the reinforcing material, a strong and flexible electrode can be obtained, and excellent long-term cycle characteristics can be exhibited. The usage-amount of electroconductivity imparting material and a reinforcing agent is 0.01-20 mass parts normally with respect to 100 mass parts of electrode active materials, Preferably it is 1-10 mass parts. By being included in the above range, high capacity and many load characteristics can be exhibited.

Examples of the dispersant include anionic compounds, cationic compounds, nonionic compounds, and high molecular compounds. The dispersant is selected according to the electrode active material and the conductive agent to be used. The content rate of the dispersing agent in an electrode becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of electrode active materials. When the amount of the dispersant is within the above range, the slurry is excellent in stability, a smooth electrode can be obtained, and high battery capacity can be exhibited.

Examples of the leveling agent include surfactants such as alkyl surfactants, silicone surfactants, fluorine surfactants, and metal surfactants. By mixing the said surfactant, the cratering which arises at the time of coating can be prevented, or the smoothness of an electrode can be improved. The content rate of the leveling agent in an electrode becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of electrode active materials. When the leveling agent is in the above range, the productivity, smoothness, and battery characteristics at the time of electrode production are excellent.

As antioxidant, a phenol compound, a hydroquinone compound, an organic phosphorus compound, a sulfur compound, a phenylenediamine compound, a polymeric phenol compound, etc. are mentioned. The polymer type phenol compound is a polymer having a phenol structure in a molecule, and a polymer type phenol compound having a weight average molecular weight of 200 to 1000, preferably 600 to 700 is preferably used. The content ratio of antioxidant in an electrode active material layer becomes like this. Preferably it is 0.01-10 mass parts, More preferably, it is 0.05-5 mass parts with respect to 100 mass parts of electrode active materials. When antioxidant is the said range, it is excellent in slurry stability, battery capacity, and cycling characteristics.

Examples of the thickener include cellulose-based polymers such as carboxymethyl cellulose, methyl cellulose and hydroxypropyl cellulose and these ammonium salts and alkali metal salts; (modified) poly (meth) acrylic acid and ammonium salts thereof and alkali metal salts; (modified) polyvinyl alcohol, Polyvinyl alcohols such as copolymers of acrylic acid or acrylate and vinyl alcohol, maleic anhydride or copolymers of maleic acid or fumaric acid and vinyl alcohol; polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, modified polyacrylic acid, and starch oxide Starch, phosphoric acid, casein, various modified starches, acrylonitrile-butadiene copolymer hydride and the like. If the usage-amount of a thickener is this range, coatability and adhesiveness with an electrode or an organic separator are favorable. In the present invention, "(modified) poly" means "unmodified poly" or "modified poly", and "(meth) acryl" means "acryl" or "methacryl". The content rate of the thickener in an electrode active material layer becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of electrode active materials. When the thickener is in the above range, it is excellent in dispersibility of active materials and the like in the slurry and a smooth electrode can be obtained, and shows excellent load characteristics and cycle characteristics.

As an electrolyte solution additive, the vinylene carbonate etc. which are used in the electrode active material slurry mentioned later and in electrolyte solution can be used. The content rate of the electrolyte solution additive in an electrode active material layer becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of electrode active materials. By the electrolyte additive being in the above range, the cycle characteristics and the high temperature characteristics are excellent. In addition, nano fine particles, such as fumed silica and fumed alumina: Surfactant, such as alkyl type surfactant, silicone type surfactant, fluorine type surfactant, and metal type surfactant. By mixing the said nanoparticles, the thixotropy of the slurry for electrode formation can be controlled, and the leveling property of the electrode obtained by it can be improved. The content rate of the nanofine particle grade in an electrode active material layer becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of electrode active materials. When nanoparticles are in the said range, it is excellent in slurry stability and productivity, and shows high battery characteristics. By mixing the said surfactant, dispersibility, such as an active material in an electrode active material slurry, can be improved, and also the smoothness of the electrode obtained by it can be improved. The content rate of surfactant in an electrode active material layer becomes like this. Preferably it is 0.01-10 mass parts with respect to 100 mass parts of electrode active materials. When surfactant is the said range, it is excellent in slurry stability and electrode smoothness, and shows high productivity.

In addition to the block polymer, the binder may further contain an optional binder component. As such arbitrary binder components, various resin components can be used together. For example, polyethylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyacrylic acid, polyacrylonitrile, polyacrylate, Polymethacrylate and the like can be used. Moreover, the copolymer containing 50% or more of said resin components can also be used, For example, polyacrylic acid derivatives, such as an acrylic acid styrene copolymer and an acrylic acid acrylate copolymer, an acrylonitrile styrene copolymer, an acrylonitrile Polyacrylonitrile derivatives, such as an acrylate copolymer, can also be used.

Moreover, the soft polymer illustrated below can also be used as a binder.

Polybutyl acrylate, polybutyl methacrylate, polyhydroxyethyl methacrylate, polyacrylamide, polyacrylonitrile, butyl acrylate styrene copolymer, butyl acrylate acrylonitrile copolymer, butyl acrylate? Acrylic soft polymer which is a homopolymer of acrylic acid or methacrylic acid derivative, such as an acrylonitrile glycidyl methacrylate copolymer, or a copolymer with the monomer copolymerizable with it; dimethyl polysiloxane, diphenyl polysiloxane, dihydroxy polysiloxane Silicon-containing soft polymers such as liquid polyethylene, polypropylene, poly-1-butene, ethylene-α-olefin copolymers, olefin-based soft polymers such as propylene-α-olefin copolymers, ethylene-propylene-styrene copolymers, and the like; Vinyl alcohol, polyvinyl acetate, polyvinyl stearate, vinyl acetate? Vinyl soft polymers such as styrene copolymers; epoxy soft polymers such as polyethylene oxide, polypropylene oxide, epichlorohydrin rubber; fluorine-containing soft polymers such as vinylidene fluoride rubber and ethylene tetrafluoride-propylene rubber; natural rubber; And other soft polymers such as polypeptides, proteins, polyester-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers. These soft polymers may have a crosslinked structure or may be functional groups introduced by modification. These may be used independently and may be used in combination of 2 or more type.

The thickness of the electrode for secondary batteries of this invention is 5-300 micrometers normally, Preferably it is 10-250 micrometers. By the electrode thickness being in the above range, both the load characteristics and the energy density exhibit high characteristics.

The electrode for secondary batteries of this invention is manufactured by the method of laminating | stacking an electrode active material layer on at least one side, preferably both surfaces of the said collector. For example, the manufacturing method of mixing the constituent material of the said electrode active material layer with a solvent, adjusting an electrode active material slurry, and apply | coating and drying an electrode active material slurry to one surface of the said electrical power collector is mentioned.

Below, the electrode active material slurry, the manufacturing method of an electrode active material slurry, and the manufacturing method of the electrode for secondary batteries are demonstrated. In addition, since the electrical power collector which is a component of the electrode for secondary batteries, an electrode active material, a block copolymer, and other containing components are the same as the above, description is abbreviate | omitted here.

(Electrode active material slurry)

The secondary battery electrode active material slurry used for this invention contains an electrode active material, a block polymer, another containing component, and a solvent.

(menstruum)

The solvent is not particularly limited as long as it can uniformly dissolve or disperse the block polymer of the present invention.

-부티로락톤, ε-카프로락톤 등의 에스테르류；아세토니트릴, 프로피오니트릴 등의 아실로니트릴류；테트라하이드로푸란, 에틸렌글리콜디에틸에테르 등의 에테르류：메탄올, 에탄올, 이소프로판올, 에틸렌글리콜, 에틸렌글리콜모노메틸에테르 등의 알코올류；N-메틸피롤리돈, N,N-디메틸포름아미드 등의 아미드류를 들 수 있다. As a solvent used for an electrode active material slurry, both water and an organic solvent can be used. As an organic solvent, Cycloaliphatic hydrocarbons, such as cyclopentane and cyclohexane; Aromatic hydrocarbons, such as toluene, xylene, and ethylbenzene; Acetone, ethyl methyl ketone, diisopropyl ketone, cyclohexanone, methylcyclohexane, Ketones such as ethylcyclohexane; ethyl acetate, butyl acetate,

Esters such as butyrolactone and ε-caprolactone; acylonitriles such as acetonitrile and propionitrile; ethers such as tetrahydrofuran and ethylene glycol diethyl ether: methanol, ethanol, isopropanol, ethylene glycol, Alcohols such as ethylene glycol monomethyl ether; amides such as N-methylpyrrolidone and N, N-dimethylformamide.

These solvents may be used alone, or two or more thereof may be mixed and used as a mixed solvent. Among these, the solvent which is excellent in the solubility of the polymer of this invention, excellent in the dispersibility of an electrode active material and a electrically conductive agent, and low in boiling point can be removed in low temperature and low temperature for a short time. Acetone, toluene, cyclohexanone, cyclopentane, tetrahydrofuran, cyclohexane, xylene, water, or N-methylpyrrolidone, or a mixed solvent thereof is preferable.

Although solid content concentration of the electrode active material slurry used for this invention is a grade which can apply | coat and immerse, and becomes a viscosity which has fluidity, it will not specifically limit, Usually, it is about 10-80 mass%.

(Method for producing electrode active material slurry)

In this invention, the manufacturing method of an electrode active material slurry is not specifically limited, It is obtained by mixing the block polymer, an electrode active material, and the solvent and arbitrary containing components added as needed.

In the present invention, the electrode active material slurry in which the electrode active material and the conductive agent are highly dispersed can be obtained regardless of the mixing method and the mixing order by using the above components. The mixing device is not particularly limited as long as it is a device capable of uniformly mixing the above components, and may be a bead mill, a ball mill, a roll mill, a sand mill, a pigment disperser, a brain trajectory, an ultrasonic disperser, a homogenizer, a planetary mixer, Although a peel mix etc. can be used, it is especially preferable to use a ball mill, a roll mill, a pigment disperser, a brain trajectory, and a planetary mixer from the point which can disperse | distribute at high concentration.

The viscosity of the electrode active material slurry is preferably from 10 mPa · s to 100,000 mPa · s, more preferably from 100 to 50,000 mPa · s from the viewpoint of uniform coatability and slurry time course stability. The said viscosity is a value when it measures by 25 degreeC and rotation amount 60rpm using a Brookfield viscometer.

(Method for Producing Electrode for Secondary Battery)

The manufacturing method of the electrode for secondary batteries of this invention should just be a method of laminating | stacking an electrode active material layer on at least one side, preferably both surfaces of the said electrical power collector. For example, a manufacturing method including the step of applying and drying the electrode active material slurry to one surface of the current collector may be mentioned.

The method of apply | coating an electrode active material slurry to an electrical power collector is not specifically limited. For example, methods, such as a doctor blade method, the zip method, the reverse roll method, the direct roll method, the gravure method, the extrusion method, the brush coating method, are mentioned. As a drying method, the drying method by irradiation with warm air, hot air, low humidity wind, vacuum drying, (far) infrared rays, an electron beam, etc. are mentioned, for example.

Subsequently, it is preferable to make the porosity of an electrode low by a pressurization process using a metal mold | die press, a roll press, etc. The range with a porosity is 5%-15%, More preferably, it is 7%-13%. If the porosity is too high, the charging efficiency and the discharge efficiency deteriorate. If the porosity is too low, a high volume capacity is hardly obtained and the electrode is easily peeled off, which causes a problem of easily causing defects. Moreover, when using a curable polymer, it is preferable to harden.

This invention is also a secondary battery comprised using the said electrode for secondary batteries or the said electrode for secondary batteries. The structure of the electrode by this invention can be applied also to a laminated battery, and can be applied also to a bipolar battery. Below, the structure of the secondary battery of this invention is demonstrated.

(Secondary battery)

The secondary battery of this invention has a positive electrode, electrolyte solution, a separator, and a negative electrode, The said positive electrode and / or negative electrode are the electrodes for secondary batteries of this invention.

Examples of the secondary battery include a lithium ion secondary battery and a nickel hydride secondary battery. Since the improvement in long-term cycle characteristics and the performance improvement such as a wide operating temperature range are most required, the lithium ion secondary battery is used as a secondary battery. desirable. Hereinafter, the case where it uses for a lithium ion secondary battery is demonstrated.

(Electrolyte for lithium ion secondary battery)

As an electrolyte solution for lithium ion secondary batteries, the organic electrolyte solution which melt | dissolved the supporting electrolyte in the organic solvent is used. Lithium salt is used as a supporting electrolyte. The lithium salt is not particularly limited, but LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO ) ₂ NLi, (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ ) NLi, and the like. Among them, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li that are easily dissolved in a solvent and exhibit high dissociation degree are preferable. These may use 2 or more types together. Since the higher the degree of dissociation of the supporting electrolyte, the higher the lithium ion conductivity, the lithium ion conductivity can be adjusted according to the type of the supporting electrolyte.

The organic solvent used for the electrolyte solution for the lithium ion secondary battery is not particularly limited as long as the supporting electrolyte can be dissolved therein, but dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), and propylene carbonate (PC ), Carbonates such as butylene carbonate (BC), methyl ethyl carbonate (MEC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; Sulfur-containing compounds such as porane and dimethyl sulfoxide are preferably used. Moreover, you may use the liquid mixture of these solvent. Among them, carbonates are preferable because the dielectric constant is high and the stable potential region is wide. The lower the viscosity of the solvent used, the higher the lithium ion conductivity, so that the lithium ion conductivity can be adjusted according to the type of solvent.

Moreover, you may use it, containing an additive in the said electrolyte solution. As an additive, carbonate type compounds, such as vinylene carbonate (VC) used in the above-mentioned electrode active material slurry, are mentioned.

The density | concentration of the supporting electrolyte in the electrolyte solution for lithium ion secondary batteries is 1-30 mass% normally, Preferably it is 5 mass%-20 mass%. In addition, it is usually used at a concentration of 0.5 to 2.5 mol / l depending on the kind of the supporting electrolyte. Even if the concentration of the supporting electrolyte is too low or too high, the ion conductivity tends to be lowered.

Examples of the electrolytic solution other than the above include polymer electrolytes such as polyethylene oxide and polyacrylonitrile, gel polymer electrolytes in which the polymer electrolyte is impregnated with an electrolyte solution, and inorganic solid electrolytes such as LiI and Li ₃ N.

(Separator for lithium ion secondary battery)

As a separator for lithium ion secondary batteries, well-known things, such as a porous resin coat containing a microporous membrane or nonwoven fabric containing inorganic polyamide resin, such as polyethylene and a polypropylene, an aromatic polyamide resin, and inorganic ceramic powder, can be used. For example, the porous film which consists of resin, such as polyolefin type (polyethylene, polypropylene, polybutene, polyvinyl chloride), and mixtures or copolymers thereof, polyethylene terephthalate, polycycloolefin, polyether sulfone, polyamide, poly The woven fabric of the microporous membrane or polyolefin fiber which consists of resins, such as mead, polyimide amide, polyaramid, polycycloolefin, nylon, polytetrafluoroethylene, or the like, nonwoven fabric, aggregate of insulating material particle, etc. are mentioned. . Among these, the microporous membrane which consists of polyolefin resin is preferable, since the thickness of the whole separator can be made thin and the ratio of the active material in a battery can be raised and the capacity | capacitance per volume can be raised.

The thickness of the separator is usually 0.5 to 40 µm, preferably 1 to 30 µm, and more preferably 1 to 10 µm. If it is this range, resistance by the separator in a battery will become small and it is excellent in workability at the time of battery manufacture.

As a specific manufacturing method of a lithium ion secondary battery, a positive electrode and a negative electrode are superposed | superposed through a separator, this is wound along a battery shape, bend | folded, it puts in a battery container, and electrolyte solution is inject | poured and sealed in a battery container. The method can be mentioned. If necessary, an over-current protection element such as an expanded metal, a fuse, a PTC element, a lead plate, or the like may be put therein to prevent pressure increase and overcharge / discharge inside the battery. The shape of the battery may be any of a coin type, a button type, a sheet type, a cylindrical shape, a square shape, and a flat type.

Example

Although an Example is given to the following and this invention is demonstrated, this invention is not limited to this. In addition, the part and% which are related to the quantity ratio of material in a present Example are a mass reference | standard unless there is particular notice.

In Examples and Comparative Examples, various physical properties were evaluated as follows.

<Battery characteristic: output characteristic>

The obtained full cell coin-type battery is charged to 4.3 V at 25 ° C. by a 0.1 C constant current method, and then discharged to 0.1 V at 0.1 C to obtain a 0.1 C discharge capacity. Thereafter, the battery was charged at 0.1 C to 4.3 V, then discharged at 20 C to 3.0 V to obtain a 20 C discharge capacity. These measurements are carried out for 10 cells of a full cell coin-type battery. The average value of the 0.1 C discharge capacity of 10 cells and the average value of the 20 C discharge capacity of 10 cells are obtained, and a and b are respectively calculated. The capacity retention ratio represented by the ratio ((b / a) × 100 (unit:%)) of the 20 C discharge capacity b and the 0.1 C discharge capacity a to the electric capacity is calculated, and this is based on the following criteria as an evaluation criteria for output characteristics. It judges by. The higher this value, the better the output characteristics.

A ： 50% or more

B: 40% or more and less than 50%

C: 20% or more but less than 40%

D ： 1% or more but less than 20%

E ： less than 1%

<Battery characteristic: cycle characteristic>

The obtained full-cell coin-type battery was charged at 0.1 C at 25 ° C. from 3 V to 4.3 V, and then repeated 100 cycles of charge / discharge to discharge at 0.1 C from 4.3 V to 3 V, followed by the fifth cycle of 0.1 C discharge. The value which computed the ratio of the 0.1 C discharge capacity of the 100th cycle with respect to the capacity | capacitance as a percentage was made into the capacity | standard retention rate, and was judged on the following reference | standard. The larger this value, the smaller the decrease in discharge capacity and the better the cycle characteristics.

A ： 70% or more

B ： 60% or more and less than 70%

C ： 50% or more and less than 60%

D ： 40% or more and less than 50%

E ： 30% or more but less than 40%

F ： less than 30%

<Battery characteristic: High temperature characteristic>

The obtained full cell coin-type battery was charged at 0.1 C at 60 ° C. from 3 V to 4.3 V, followed by 20 cycles of charge / discharge to discharge at 0.1 C from 4.3 V to 3 V, followed by the fifth cycle of 0.1 C discharge. The value which computed the ratio of the 0.1 C discharge capacity of the 20th cycle with respect to the capacity | capacitance as a percentage was made into the capacity | standard retention ratio, and was judged on the following reference | standard. The larger this value, the smaller the discharge capacity decreases, and the higher the temperature characteristic is.

A ： 70% or more

B ： 60% or more and less than 70%

C ： 50% or more and less than 60%

D ： 40% or more and less than 50%

E ： 30% or more but less than 40%

F ： less than 30%

<Battery characteristic: Low temperature characteristic>

The obtained full cell coin-type battery is charged with a constant current until the charge / discharge rate is set to 0.1 C at 25 ° C., and becomes 4.3 V by the constant current constant voltage charging method, followed by charging at a constant voltage. Subsequently, it discharges to 3.0V at 0.1C, and calculates the discharge capacity in 25 degreeC. Then, constant current constant voltage charge was performed at 0.1 C in the thermostat set to -20 degreeC. Battery capacity at 25 degreeC is a and battery capacity at -20 degreeC is b. The low-temperature capacity retention ratio expressed by the ratio ((b / a) x 100 (unit:%)) of the discharge capacity b at -20 ° C and the discharge capacity of the battery capacity a at 25 ° C was obtained. It was judged based on the following criteria. It shows that it is a battery with favorable lithium water solubility at low temperature, so that this value is large.

A ： 70% or more

B ： 60% or more and less than 70%

C ： 50% or more and less than 60%

D ： 40% or more and less than 50%

E ： 30% or more but less than 40%

F ： less than 30%

(Example 1)

<Synthesis of Block Copolymer>

Into a four-necked flask equipped with a mechanical stirrer, a nitrogen inlet, a cooling tube, and a rubber septum, 100 parts of toluene and 40 parts of styrene were added, and 1.3 parts of 2,2'-bipyridine were added thereto, The system was nitrogen-substituted. After adding 0.41 part of copper bromide to this under nitrogen stream, the reaction system was heated to 90 degreeC, and 0.21 part of 2-bromo-2-methylpropionic acid 2-hydroxyethyl was added as an initiator, and superposition | polymerization is started and nitrogen Under the air stream, the polymerization was carried out at 90 ° C. for 9 hours. After confirming that the polymerization rate (a ratio defined by the weight of the polymer obtained by heating and removing the volatile component by the weight of the polymer as it is before removing the volatile component) was 90% or more, rubber 60 parts n-butyl acrylate was added thereto. It added from septum and heated again at 110 degreeC for 12 hours. In this way, a toluene solution of a block copolymer of styrene-butyl acrylate was obtained. Subsequently, the obtained block copolymer solution was put into the autoclave with a stirrer. Subsequently, a hydrogenation catalyst solution in which 0.1 part of tris (tricyclohexylphosphine) ruthenium (II) dichloride was dissolved in 5 parts of toluene was added, followed by hydrogenation reaction at a hydrogen pressure of 0.9 MPa and 160 ° C. for 8 hours, and at the growth end. The bromo group was hydrogenated. After adding 10 parts of sulfonic acid type cation exchange resin to 100 parts of the block copolymer, stirring at 120 ° C. for 2 hours, the ion exchange resin was removed, and the polymerization catalyst, the hydrogenation catalyst and the like were further removed, and the solidification and drying were performed. Polymer-1 having a polymerization unit content of about 40% based on colorless transparent styrene was obtained. The molecular weight distribution (Mw / Mn) was 1.2 to 1.3. The composition, the ratio, the weight average molecular weight, and the glass transition temperature of the obtained polymer-1 are shown in Table 1. The glass transition temperature was measured by differential scanning calorimetry (DSC method) at a temperature increase rate of 20 ° C./min from -120 ° C. to 120 ° C. by differential scanning calorimetry (manufactured by Seiko Instruments Inc., product name “EXSTAR6000”). . The weight average molecular weight was dissolved polymer 1 in tetrahydrofuran to make a 0.2% by weight solution, then filtered through a membrane filter of 0.45 μm, using gel permeation chromatography (GPC) under the following conditions as a measurement sample. It measured and calculated | required the weight average molecular weight of standard polystyrene conversion.

Measuring apparatus: HLC-8220GPC (manufactured by Tosoh Corporation)

Column: TSKgel Multipore HXL-M (manufactured by Tosoh Corporation)

Eluent: tetrahydrofuran (THF)

Elution rate: 0.3 ml / min

Detector: RI (polarity (+))

Column temperature: 40 degrees Celsius

<Production of Block Polymer Solution>

The obtained polymer-1 was dissolved in N-methyl-2-pyrrolidone (hereinafter referred to as NMP) to obtain an NMP solution of polymer-1 having a solid content concentration of 20%.

<Production of an Electrode Composition for Negative Electrodes and a Negative Electrode>

98 parts of graphite having a particle diameter of 20 µm and a specific surface area of 4.2 m 2 / g as a negative electrode active material, and 5 parts of PVDF (polyvinylidene fluoride) as a solid content as a binder are mixed, and N-methylpyrrolidone is further added to the planar It mixed by the electric mixer and prepared the slurry-like electrode composition for negative electrodes (slurry for negative electrode active material layer formation). After apply | coating this electrode composition for negative electrodes to the single side | surface of the copper foil of thickness 10micrometer, and drying at 110 degreeC for 3 hours, it roll-pressed and obtained the negative electrode which has a negative electrode active material layer of thickness 60micrometer.

<Production of the electrode composition for the positive electrode and the positive electrode>

92 parts of lithium manganate having a spinel structure as a positive electrode active material, 5 parts of acetylene black, and 3 parts of NMP solution of Polymer-1 as solids are added as solids, and after adjusting to a solid content concentration of 87% by NMP, the planar Mix 60 minutes with a battery mixer. Furthermore, after adjusting to 84% of solid content concentration by NMP, it mixed for 10 minutes, and prepared the slurry-shaped electrode composition for positive electrodes (positive electrode active material slurry). This electrode composition for positive electrodes was apply | coated to the aluminum foil of 18 micrometers in thickness, and after drying at 120 degreeC for 3 hours, it roll-pressed and obtained the positive electrode which has a 50-micrometer-thick positive electrode active material layer.

<Production of battery>

Next, the obtained positive electrode was cut out circularly [diameter 13mm]. The obtained negative electrode was cut out circularly [diameter 14mm]. The polypropylene separator (porosity 55%) of the monolayer manufactured by the dry method of thickness 25micrometer was cut out circularly [diameter 18mm]. These were housed in a stainless steel coin-type outer container (diameter 20 mm, height 1.8 mm, stainless steel thickness 0.25 mm) provided with polypropylene packing. The arrangement of the circular electrode and the separator in the outer container was as follows. The circular positive electrode was arrange | positioned so that the aluminum foil might contact the bottom face of an exterior container. The circular separator was arrange | positioned so that it may interpose between the circular positive electrode and the negative electrode with a circular porous film. The negative electrode with a circular porous membrane was arranged so that the surface on the porous membrane side would face the surface on the positive electrode active material layer side of the circular positive electrode via the circular separator. In addition, the expanded metal is placed on the copper foil of the negative electrode, the electrolyte (EC / DEC = 1/2, 1M LiPF ₆ ) is injected into the vessel so that no air remains, and the outer container is interposed through a polypropylene packing. A 0.2 mm thick stainless steel cap was capped and fixed, and the battery can was sealed to prepare a full cell coin cell having a diameter of 20 mm and a thickness of about 3.2 mm (coin cell CR2032). The output characteristics, cycle characteristics, high temperature characteristics, and low temperature characteristics of the obtained battery were measured. The results are shown in Table 2.

(Examples 2-5)

A positive electrode active material slurry, a positive electrode, and a battery were prepared in the same manner as in Example 1 except that Polymer-2 to 5, which is composed of the composition and weight average molecular weight shown in Table 1 as a binder constituting the positive electrode, was used. And the output characteristic, the cycle characteristic, the high temperature characteristic, and the low temperature characteristic of the obtained battery were evaluated. The results are shown in Table 2. The molecular weight distribution (Mw / Mn) of the polymers 2-5 was all 1.2-1.3.

(Example 6)

The time of the polymerization reaction at 90 degreeC after adding styrene and other substance (initiator etc.) to a flask was changed from 9 to 36 hours, and the time heated to 110 degreeC after adding n-butyl acrylate to the reaction mixture Except having changed from 12 hours to 48 hours, the block polymer was synthesize | combined like Example 1 and the polymer-6 was obtained. The composition, the ratio, the weight average molecular weight, and the glass transition temperature of the obtained polymer-6 are shown in Table 1. The molecular weight distribution (Mw / Mn) of the polymer 6 was 1.2-1.3.

A positive electrode active material slurry, a positive electrode, and a battery were prepared in the same manner as in Example 1 except that Polymer-6 was used instead of Polymer-1 as the binder constituting the positive electrode. And the output characteristic, the cycle characteristic, the high temperature characteristic, and the low temperature characteristic of the obtained battery were evaluated. The results are shown in Table 2.

(Example 7)

The time of the polymerization reaction at 90 degreeC after putting styrene and other substance (initiator etc.) in a flask is changed from 9 hours to 1 hour, and the time heated to 110 degreeC after adding n-butyl acrylate to the reaction mixture Except having changed from 12 hours to 2 hours, the block polymer was synthesize | combined like Example 1 and the polymer-7 was obtained. The composition, the ratio, the weight average molecular weight, and the glass transition temperature of the obtained polymer-7 are shown in Table 1. The molecular weight distribution (Mw / Mn) of the polymer 7 was 1.2-1.3.

A positive electrode active material slurry, a positive electrode and a battery were prepared in the same manner as in Example 1 except that Polymer-7 was used instead of Polymer-1 as the binder constituting the positive electrode. And the output characteristic, the cycle characteristic, the high temperature characteristic, and the low temperature characteristic of the obtained battery were evaluated. The results are shown in Table 2.

(Example 8)

Into a four-necked flask equipped with a mechanical stirrer, a nitrogen inlet, a cooling tube, and a rubber septum, 100 parts of toluene and 40 parts of styrene were added, and 1.3 parts of 2,2'-bipyridine were added thereto, The system was nitrogen-substituted. After adding 0.41 part of copper bromide to this under nitrogen stream, the reaction system was heated to 90 degreeC, and 0.21 part of 2-bromo-2-methylpropionic acid 2-hydroxyethyl was added as an initiator, and superposition | polymerization is started and nitrogen Under the air stream, the polymerization was carried out at 90 ° C. for 3 hours. After confirming that the polymerization rate (weight defined by dividing the weight of the polymer by heating and removing the volatile component by the weight of the polymer as it is before removing the volatile component) is 90% or more, 50 parts of n-butyl acrylate and A mixture of 10 parts of acrylic acid was added from the rubber septum, which was further heated at 110 ° C. for 7 hours. In this way, a toluene solution of a block copolymer of styrene-butyl acrylate / acrylic acid was obtained. Subsequently, the obtained block copolymer solution was put into the autoclave with a stirrer. Subsequently, a hydrogenation catalyst solution in which 0.1 part of tris (tricyclohexylphosphine) ruthenium (II) dichloride was dissolved in 5 parts of toluene was added, followed by hydrogenation reaction at a hydrogen pressure of 0.9 MPa and 160 ° C. for 8 hours, thereby The bromo group was hydrogenated. After adding 10 parts of sulfonic acid type cation exchange resin to 100 parts of the block copolymer, stirring at 120 ° C. for 2 hours, the ion exchange resin was removed, and the polymerization catalyst, the hydrogenation catalyst and the like were further removed, and the solidification and drying were performed. A polymer-8 having a polymerization unit content of about 40% based on colorless transparent styrene was obtained. The composition, the ratio, the weight average molecular weight, and the glass transition temperature of the obtained polymer-8 are shown in Table 1. The molecular weight distribution (Mw / Mn) of the polymer 8 was 1.2-1.3.

A positive electrode active material slurry, a positive electrode and a battery were prepared in the same manner as in Example 1 except that Polymer-8 was used instead of Polymer-1 as the binder constituting the positive electrode. And the output characteristic, the cycle characteristic, the high temperature characteristic, and the low temperature characteristic of the obtained battery were evaluated. The results are shown in Table 2.

(Comparative Example 1)

Polymer-9 (random copolymer of n-butyl acrylate and styrene, polymerized unit based on n-butyl acrylate, based on styrene) consisting of the composition and weight average molecular weight shown in Table 1 as a binder constituting the electrode. A positive electrode active material slurry, an electrode, and a battery were produced in the same manner as in Example 1, except that the mass ratio of polymerized units to 60/40) was used. And the output characteristic, the cycle characteristic, the high temperature characteristic, and the low temperature characteristic of the obtained battery were evaluated. The results are shown in Table 2.

(Comparative Example 2)

In Example 1, the positive electrode active material slurry, the electrode, and the battery were produced like Example 1 except having used polyvinylidene fluoride instead of the polymer-1 as a binder which comprises an electrode. And the output characteristic, the cycle characteristic, the high temperature characteristic, and the low temperature characteristic of the obtained battery were evaluated. The results are shown in Table 2.

In addition, in Table 1-Table 2, "BA" is n-butyl acrylate, "ST" is styrene, "AN" is acrylonitrile, "2EHA" is 2-ethylhexyl acrylate, "AA" is acrylic acid, "PVDF" Represents polyvinylidene fluoride.

According to the present invention, as shown in Examples 1 to 8, by using a block polymer that does not contain a halogen atom and does not have an unsaturated bond in the main chain, the secondary battery electrode can be used for output characteristics, cycle characteristics, high temperature characteristics, A battery excellent in low temperature characteristics can be obtained. Also in the examples, the block polymer has n-butyl acrylate as segment A having high compatibility with the electrolyte solution and styrene as segment B having low compatibility, and the ratio of segment A to segment B is 30:70 to 70. Example 1 which used the block polymer in the range of: 30 as a binder was excellent in all the output characteristics, cycling characteristics, high temperature characteristics, and low temperature characteristics, and showed the outstanding effect especially in output characteristics and cycling characteristics.

On the other hand, the thing using the polymer which does not have a block structure (comparative example 1), and the thing using the binder containing a halogen atom (comparative example 2) have inferior output characteristics, cycling characteristics, high temperature characteristics, and low temperature characteristics, and especially high temperature It is remarkably inferior in a characteristic.

Claims (10)

The secondary battery electrode which has an electrical power collector and the electrode active material layer which consists of a block copolymer and an electrode active material which do not contain a halogen atom and which do not contain an unsaturated bond in a principal chain formed on the said electrical power collector. The method of claim 1,
The electrode for secondary batteries which the said block copolymer has the segment which shows compatibility with the electrolyte solution containing ethylene carbonate and diethyl carbonate, and the segment which does not show compatibility with the said electrolyte solution. The method of claim 1,
The electrode for secondary batteries, wherein the block copolymer comprises a segment of a soft polymer having a glass transition temperature of 15 ° C. or less. The method of claim 1,
The electrode for secondary batteries whose weight average molecular weights of the said block copolymer exist in the range of 1,000-500,000. The binder for secondary battery electrodes containing the block copolymer which does not contain a halogen atom and does not contain an unsaturated bond in a principal chain. The method of claim 5, wherein
The binder for secondary battery electrodes in which the said block copolymer has the segment which shows compatibility with the electrolyte solution containing ethylene carbonate and diethyl carbonate, and the segment which does not show compatibility with the said electrolyte solution. The method of claim 5, wherein
The binder for secondary battery electrodes, wherein the block copolymer comprises a segment of a soft polymer having a glass transition temperature of 15 ° C. or less. The method of claim 5, wherein
The binder for secondary battery electrodes whose weight average molecular weight of the said block copolymer exists in the range of 1,000-500,000. The secondary of Claim 1 which includes the process of apply | coating the slurry of a block copolymer which does not contain a halogen atom, and which does not contain an unsaturated bond in a main chain, and an electrode active material on a collector, and dries. The manufacturing method of the battery electrode. As a secondary battery having a positive electrode, an electrolyte, a separator, and a negative electrode,
The secondary battery whose said positive electrode and / or negative electrode is the electrode for secondary batteries of Claim 1.