CN105637682A

CN105637682A - Slurry composition for negative electrodes of lithium ion secondary batteries, negative electrode for lithium ion secondary batteries, lithium ion secondary battery and production method

Info

Publication number: CN105637682A
Application number: CN201480056525.5A
Authority: CN
Inventors: 园部健矢; 松尾祐作; 浅野顺一; 韩丹
Original assignee: Nippon Zeon Co Ltd
Current assignee: Zeon Corp
Priority date: 2013-10-28
Filing date: 2014-10-23
Publication date: 2016-06-01
Also published as: KR102301032B1; JPWO2015064465A1; JP6645187B2; WO2015064465A1; KR20160077058A

Abstract

A slurry composition for negative electrodes of lithium ion secondary batteries, which contains 100 parts by mass of (A) an active material, from 0.1 part by mass to 10 parts by mass (inclusive) of (B) a water-soluble thickening agent having a carboxyl group, from 0.1 part by mass to 5 parts by mass (inclusive) of (C) a particulate binder, from 0.01 part by mass to 5 parts by mass (inclusive) of (D) a crosslinking agent and water, and wherein the ratio of the components having a molecular weight of 3,000 or less in the slurry composition relative to the total solid content of the slurry composition is 0.10% by mass or less as determined by gel permeation chromatography; a method for producing this slurry composition for negative electrodes of lithium ion secondary batteries; a negative electrode which uses this slurry composition for negative electrodes of lithium ion secondary batteries; and a secondary battery which uses this negative electrode.

Description

Lithium ion secondary battery negative pole paste compound, lithium ion secondary battery cathode, lithium rechargeable battery and manufacture method

Technical field

The present invention relates to the manufacture method of lithium ion secondary battery negative pole paste compound, lithium ion secondary battery cathode, lithium rechargeable battery and lithium ion secondary battery negative pole paste compound.

Background technology

Lithium rechargeable battery is small-sized, lightweight and energy density high and has and can repeat the such characteristic of discharge and recharge, has been used for extensive use. For lithium rechargeable battery, it is desirable to there is the performances such as high cycle characteristics, high discharging-rate performance. In recent years, in order to realize the further high performance of secondary cell, the improvement having been for the battery components such as electrode has been studied. Such as, have studied and closed in the paste compound of sheet material layers at the negative pole for forming lithium rechargeable battery, except the water-soluble thickener such as active substance, carboxymethyl cellulose and particle shape binding agent, be also added with the technology of cross-linking agent. By adding such cross-linking agent, can expect that the effect utilizing the expansion etc. of electrode conjunction sheet material layers when suppressing battery to use improves the performance (such as, patent documentation 1��2) of battery.

Prior art literature

Patent documentation

Patent documentation 1: Japanese Unexamined Patent Publication 2000-106189 publication

Patent documentation 2: Japanese Unexamined Patent Publication 2012-69457 publication

Summary of the invention

The problem that invention to solve

But, because of the existence of the compositions such as the particle shape binding agent that uses, even if the cross-linking agent that add also cannot demonstrate effect more sometimes. In this case, if adding cross-linking agent in large quantities to demonstrate the effect of cross-linking agent, then may result in negative pole to close sheet material layers and be attached to the intensity (peel strength) of collector body and reduce on the contrary, it is impossible to obtain speed characteristic, the such desired effect of cycle characteristics.

Based on this, it is an object of the invention to provide the expansion closing sheet material layers is inhibited, peel strength is high, speed characteristic high and cycle characteristics is high lithium ion secondary battery cathode and be able to easily form lithium ion secondary battery negative pole paste compound and the manufacture method thereof of such negative pole.

It is a further object to and speed characteristic and the high lithium rechargeable battery of cycle characteristics are provided.

The method of solution problem

The present inventor has studied for achieving the above object. And then, the inventors discovered that, in paste compound exist oligomer can react with cross-linking agent and consume cross-linking agent, obstruction cross-linking agent effect display. Namely, when being prepared the paste compositions such as particle shape binding agent by polyreaction etc., in order to remove the unwanted compositions such as unreacted monomer remaining in reaction system, it is heated the operations such as decompression distillation, but in such operation, the oligomer that boiling point is higher than unreacted monomer is difficult to be removed and left behind, and this will consume cross-linking agent. Additionally, the present inventors have additionally discovered that, by making the content of the low-molecular-weight water soluble ingredients such as such oligomer give following scope, the lithium ion secondary battery cathode that the expansion closing sheet material layers is inhibited, peel strength is high, speed characteristic is high and cycle characteristics is high can be obtained, and then complete the present invention. That is, according to the present invention, it is possible to provide following [1]��[7].

[1] a kind of lithium ion secondary battery negative pole paste compound, it comprises:

Active substance (A) 100 mass parts,

Have below more than water-soluble thickener (B) 0.1 mass parts of carboxyl and 10 mass parts,

More than particle shape binding agent (C) 0.1 mass parts and below 5 mass parts,

More than cross-linking agent (D) 0.01 mass parts and below 5 mass parts and

Water,

Relative to all solids composition of above-mentioned paste compound, the ratio utilizing the composition of the molecular weight less than 3000 in the above-mentioned paste compound of gel permeation chromatography is below 0.10 mass %.

[2] paste compound described in above-mentioned [1], wherein, the tap density of above-mentioned active substance (A) is more than 0.70.

[3] above-mentioned [1] or [2] described in paste compound, wherein, above-mentioned cross-linking agent (D) has carbodiimide structure.

[4] paste compound according to any one of above-mentioned [1]��[3], wherein, above-mentioned particle shape binding agent (C) has the functional group reacted with above-mentioned cross-linking agent (D), and described functional group is the group in carboxyl, hydroxyl, glycidyl ether, thiol and their combination.

[5] a kind of lithium ion secondary battery cathode, it has the negative pole conjunction sheet material layers that the paste compound according to any one of [1]��[4] obtains.

[6] a kind of lithium rechargeable battery, it possesses: lithium ion secondary battery cathode described in [5], positive pole, electrolyte and dividing plate.

[7] manufacture method of a kind of paste compound, it is the method manufacturing the paste compound according to any one of [1]��[4], wherein, the method includes active substance (A) 100 mass parts, has below more than water-soluble thickener (B) 0.1 mass parts of carboxyl and 10 mass parts, comprises below more than the compositions (CX) of below more than particle shape binding agent (C) 0.1 mass parts and 5 mass parts, cross-linking agent (D) 0.01 mass parts and 5 mass parts and water carries out the operation that mixes

Relative to all solids composition in above-mentioned composition (CX), the ratio utilizing the composition of molecular weight less than 3000 in the above-mentioned composition (CX) of gel permeation chromatography is below 0.01 mass %.

The effect of invention

Lithium ion secondary battery negative pole paste compound according to the present invention, it is possible to be easily manufactured the lithium ion secondary battery cathode that the expansion closing sheet material layers is inhibited, peel strength is high, speed characteristic is high and cycle characteristics is high. It addition, the manufacture method of the lithium ion secondary battery negative pole paste compound according to the present invention, it is possible to it is easily manufactured the paste compound that can be shown that such effect.

The lithium ion secondary battery cathode of the present invention can become the negative pole that the expansion closing sheet material layers is inhibited, peel strength is high, speed characteristic is high and cycle characteristics is high.

The lithium rechargeable battery of the present invention can become speed characteristic height and the high battery of cycle characteristics.

Detailed description of the invention

Hereinafter, in conjunction with embodiment and illustrative material, the present invention is described in detail. But the present invention is not limited to embodiments described below and illustrative material, it is possible at random change in without departing from the claim of the present invention and the scope of equivalency range thereof and implement.

[1. lithium ion secondary battery negative pole paste compound]

The lithium rechargeable battery paste compound of the present invention comprises: active substance (A), water-soluble thickener (B), particle shape binding agent (C), cross-linking agent (D) and water.

[1.1. active substance (A)]

As active substance (A), can suitably select to use the material that can use in the negative pole of secondary cell as active substance, the material given and accepted namely carrying out electronics. Negative electrode active material as lithium rechargeable battery, it is common to use can occlusion and release lithium material. As can occlusion and release lithium material, can enumerate such as: carbons negative electrode active material, metal class negative electrode active material and the negative electrode active material etc. that they are combined.

Described carbons negative electrode active material refers to and can embed (also referred to as " doping ") lithium, active substance using carbon as main bone lattice, as carbons negative electrode active material, can enumerate such as carbonaceous material and graphite material.

Carbonaceous material by by carbon precursor 2000 DEG C of heat treated below so that its carbonization and obtain, the material of degree of graphitization low (namely crystallinity is low). The lower limit of heat treatment temperature during carbonization is not particularly limited, it is possible to for more than such as 500 DEG C.

It addition, as carbonaceous material, can enumerate such as: easily change according to heat treatment temperature the structure of carbon easy to be graphitic carbon, be representative with glassy carbon the graphitic carbon of difficulty etc. with the structure close with non crystalline structure.

Here, as easy graphitic carbon, can enumerate such as: using the tar asphalt that obtained by oil or coal as the material with carbon element of raw material. As concrete example, can enumerate: coke, carbonaceous mesophase spherules (MCMB), mesophase pitch based carbon fiber, thermal decomposition gas-phase growth of carbon fibre etc.

It addition, as difficult graphitic carbon, can enumerate such as: phenolic resin fired body, polyacrylonitrile based carbon fiber, quasi-isotropic carbon, furfuryl alcohol resin fired body (PFA), hard carbon etc.

Graphite material obtains by easy graphitic carbon being carried out heat treatment more than 2000 DEG C, has the material of the high crystalline close to graphite. The upper limit of heat treatment temperature is not particularly limited, it is possible to for less than such as 5000 DEG C.

It addition, as graphite material, can enumerate such as: native graphite, Delanium etc.

Here, as Delanium, can enumerate such as: the Delanium that the carbon comprising easy graphitic carbon is mainly obtained at 2800 DEG C of heat treatments carried out above, the graphitization MCMB that MCMB is obtained at 2000 DEG C of heat treatments carried out above, graphitized intermediate-phase pitch-based carbon fiber etc. that mesophase pitch based carbon fiber is obtained at 2000 DEG C of heat treatments carried out above.

Described metal class negative electrode active material is the active substance comprising metal, it is common that refer to comprise in the structure can embed lithium element, preferably in the active substance that theoretical capacity is more than 500mAh/g of per unit mass when embedding lithium. The upper limit of theoretical capacity now is not particularly limited, it is possible to for such as 4000mAh/g. As metal class active substance, can use such as: lithium metal, the elemental metals (such as, Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, Zn, Ti etc.) that lithium alloy can be formed and alloy and their oxide, sulfide, nitride, silicide, carbide, phosphide etc.

And then, in metal class negative electrode active material, it is preferable that comprise the active substance (silicon class negative electrode active material) of silicon. It reason for this is that, by using silicon class negative electrode active material, it may be achieved the high capacity of lithium rechargeable battery.

As silicon class negative electrode active material, can enumerate such as: silicon (Si), the alloy comprising silicon, SiO, SiOx, mixture containing Si material and material with carbon element, utilize conductive carbon cladding containing Si material or to utilize conductive carbon and the compound compound etc. containing Si material Yu conductive carbon carrying out Composite containing Si material.

As the alloy comprising silicon, can enumerate such as: comprise silicon, aluminum and ferrum, and comprise the alloy of the rare earth element such as stannum and yttrium further. Such alloy such as can pass through melt spinning method (meltspunmethod) to be prepared. And then, as such alloy, the alloy such as recorded in Japanese Unexamined Patent Publication 2013-65569 publication can be enumerated.

SiOx is containing SiO and SiO₂In at least one and containing the compound of Si, x is generally 0.01 less than 2. Further, SiOx may utilize the dismutation reaction of such as silicon monoxide (SiO) and formed. Specifically, can pass through SiO is optionally carried out heat treatment under the existence of the polymer such as polyvinyl alcohol, make silicon generate with silicon dioxide, thus prepare SiOx. Heat treatment can after being optionally pulverized and mixed SiO with polymer, and in comprising the atmosphere of organic gas and/or steam, the temperature more than more than 900 DEG C, preferably 1000 DEG C carries out.

As the mixture containing Si material Yu material with carbon element, can enumerate: by silicon, SiOx etc. containing Si material and the material with carbon element such as carbonaceous material, graphite material, optionally carry out being pulverized and mixed under the existence of the polymer such as polyvinyl alcohol and the material that obtains. As carbonaceous material, graphite material, the material that can use can be used as carbons negative electrode active material.

As the compound compound containing Si material Yu conductive carbon, can enumerate such as: following crushed mixture is carried out heat treatment in such as comprising the atmosphere of organic gas and/or steam and the compound that obtains, described crushed mixture be the polymer such as SiO and polyvinyl alcohol and optionally with the crushed mixture of material with carbon element. Furthermore it is possible to adopt: by employing the method that the surface of the particle of SiO is coated with by the chemical vapor deposition method of organic gas etc.; Utilize mechanochemical reaction that the particle of SiO and graphite or Delanium carry out the known methods such as the method for compound particle (pelletize).

Here, when using carbons negative electrode active material, metal class negative electrode active material as negative electrode active material, these negative electrode active materials can expand with discharge and recharge and shrink. Therefore, when using these negative electrode active materials, typically, there are cause negative pole to expand gradually because of the expansion repeatedly of negative electrode active material and contraction, probability that secondary cell deforms and causes the electrical characteristic such as cycle characteristics to reduce. But, for the negative pole formed with regard to the paste compound of the use present invention, owing to the expansion of negative pole is inhibited, therefore, it is possible to improve the characteristics such as cycle characteristics.

If using above-mentioned silicon class negative electrode active material, although being then capable of the high capacity of lithium rechargeable battery, but generally, can there is significantly (such as 5 times of degree) expansion and contraction with discharge and recharge in silicon class negative electrode active material. Therefore, from the view point of while the generation fully suppressing negative pole to expand, make lithium rechargeable battery realize high capacity, it is preferred to use the mixture of carbons negative electrode active material and silicon class negative electrode active material is as negative electrode active material.

Here, when the mixture of use carbons negative electrode active material and silicon class negative electrode active material is as negative electrode active material, from while fully suppressing the generation that negative pole expands, the viewpoint that lithium rechargeable battery fully realizes high capacity is made to set out, as carbons negative electrode active material, Delanium is preferably used, as silicon class negative electrode active material, it is preferably used selected from Si, comprise the alloy of silicon, SiOx, mixture containing Si material Yu material with carbon element, and more than one in the compound compound containing Si material and conductive carbon, as silicon class negative electrode active material, it is preferred that use the alloy comprising silicon, and at least one in the compound compound containing Si material and conductive carbon, particularly preferably use the alloy comprising silicon, and in the substrate of conductive carbon, it is dispersed with at least one in the compound compound (Si-SiOx-C complex) of SiOx. these negative electrode active materials can occlusion and release larger amount of lithium, on the other hand, the change in volume in occlusion and when releasing lithium is less. therefore, if using these negative electrode active materials, then can when suppressing discharge and recharge while the increase of the change in volume of negative electrode active material, the lithium rechargeable battery employing the lithium ion secondary battery cathode utilizing paste compound and formed realizes high capacity fully. it addition, when using the alloy comprising silicon, it is possible to while fully realizing the high capacity of lithium rechargeable battery, also make Initial Coulombic Efficiencies, cycle characteristics improve.

Additionally, when the mixture of use carbons negative electrode active material and silicon class negative electrode active material is as negative electrode active material, from the view point of while the generation fully suppressing negative pole to expand, make lithium rechargeable battery fully realize high capacity, it is preferable that in negative electrode active material, the ratio of the silicon class negative electrode active material of 100 mass parts every relative to carbons negative electrode active material is in specific scope. Namely, in preferred negative electrode active material, 100 mass parts every relative to carbons negative electrode active material are containing the silicon class negative electrode active material having more than below 0 mass parts and 100 mass parts, more preferably below more than 10 mass parts and 70 mass parts are contained, it is particularly preferred to containing more than 30 mass parts and below 50 mass parts. By making negative electrode active material comprise silicon class negative electrode active material (that is, making the amount of silicon class negative electrode active material of 100 mass parts every relative to carbons negative electrode active material more than 0 mass parts), it is possible to fully realize the high capacity of lithium rechargeable battery. It addition, the amount of the silicon class negative electrode active material by making 100 mass parts every relative to carbons negative electrode active material is below 100 mass parts, it is possible to fully suppress the generation that negative pole expands.

[1.1.1. active substance (A): tap density]

The tap density of active substance (A) is preferably more than 0.70, is more preferably more than 0.75, more preferably more than 0.80, further preferably more than 0.85. By making tap density be such high level, it is possible to improve peel strength, therefore, in demonstrating the present invention of effect of cross-linking agent (D) well, it is possible to obtain higher effect. The upper limit of tap density is not particularly limited, for instance can be less than 1.50.

The tap density of active substance (A) depends on the method for making of active substance and determines. Therefore, only by from as the various active substances that commercially available prod etc. obtains select desired active substance, can obtaining desired tap density. It addition, by various active material mixing different for tap density is used, it is possible to regulate the tap density of active substance (A).

[1.1.2. is about active substance (A): other]

Active substance (A) is preferably particle shape by granulate. When being shaped as spherical of particle, can form more highdensity electrode during electrode moulding.

When active substance (A) is for particle, its volume average particle size it is contemplated that the balance of other constitutive requirements with secondary cell suitably selects. The volume average particle size of the particle of concrete negative electrode active material is generally more than 0.1 ��m, is preferably more than 1 ��m, is more preferably more than 3 ��m, is generally less than 100 ��m, is preferably less than 50 ��m, is more preferably less than 30 ��m. Here, what volume average particle size adopted is in the particle size distribution utilizing laser diffractometry to measure from childhood particle diameter side play the cumulative volume of calculating and reach the particle diameter of 50%.

From the view point of improve output density, the specific surface area of active substance (A) is generally 0.3m²/ more than g, preferably 0.5m²/ more than g, it is more preferably 0.8m²/ more than g, is generally 20m²/ below g, preferably 10m²/ below g, it is more preferably 5m²/ below g. The specific surface area of negative electrode active material such as can be measured by BET method.

[1.2. water-soluble thickener (B)]

Water-soluble thickener (B) is the water miscible thickening agent with carboxyl. Water-soluble thickener (B) can as the viscosity modifier function of paste compound. It addition, the negative pole that the paste compound with regard to utilizing the present invention obtains closes for sheet material layers, negative pole closes the physical property of sheet material layers and is held in suitable state, and its result can make the characteristic such as cycle characteristics, speed characteristic good.

The quantity of the carboxyl in water-soluble thickener (B) is preferably 0.01 mmoles/g��20 mmoles/g, is more preferably 0.02 mmoles/g��15 mmoles/g. By having the carboxyl of the quantity within the scope of this, it is possible to obtain physical property such as good coating performances.

In the application, thickening agent refers to for " water solublity ": when making to comprise the specific sample of polymer and water by the sieve of 250 orders, does not pass through sieve and remains in the quality of the solid constituent of residue on the sieve solid constituent relative to the thickening agent added less than 50 mass %.

Here, specific sample is 100 mass parts every relative to ion exchange water to be added thickening agent 1 mass parts (with solid component meter) and the mixture that is stirred and obtains adjusts the sample to following condition, and described condition is at least one condition in the condition that temperature is more than 20 and in the scope of less than 70 DEG C and pH is more than 3 and in the scope of less than 12 (use NaOH aqueous solution and/or HCl/water solution are to adjust pH).

Even if the mixture of above-mentioned thickening agent and water is the emulsion state being separated into two-phase when standing, as long as meeting above-mentioned definition, namely specify that this thickening agent is water solublity.

As water-soluble thickener (B), if enumerating natural goods class, then can enumerate: carboxymethyl cellulose, carboxymethyl starch, alginic acid, poly-aspartate, their salt and their mixture; If enumerating synthesis class, then can enumerate: polycarboxylic acids, cross linked polyacrylate, acrylamide and acrylic acid copolymer, nitrile-acrylamide-acrylic acid nitrile-acrylic copolymer, acrylamide and acrylic acid-2-acrylamide-2-methyl propane sulfonic copolymer, acrylamide and acrylic acid-methacrylic acid copolymer, acrylic acid-acrylonitrile-acrylic acid 2-hydroxy methacrylate copolymer, other and acrylic acid, the copolymer of methacrylic acid, their salt and their mixture. It addition, in the water-soluble polymer of above-mentioned synthesis class, it is also possible to it is the use of dimethacrylated compound or the crosslinking structural body of the cross-linking agent such as divinylbenzene, diallyl compound. Wherein, it may be preferable to use has carboxyl, is used as the various polymer of thickening agent. Specifically, carboxymethyl cellulose, polycarboxylic acids, their salt etc. can be used. Wherein, as polycarboxylic acids, polyacrylic acid, polymethylacrylic acid, alginic acid etc. can be enumerated. These water-soluble thickeners (B) can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

Water-soluble thickener (B) particularly preferably comprises carboxymethyl cellulose or its salt (being also abbreviated as " carboxymethyl cellulose (salt) " below). By making water-soluble thickener (B) comprise carboxymethyl cellulose (salt), it is possible to make to coat paste compound collector body first-class time workability more good.

Here, when using carboxymethyl cellulose (salt) as water-soluble thickener (B), the degree of etherification falling of the carboxymethyl cellulose (salt) used is preferably more than 0.4, is more preferably more than 0.7, it is preferred to less than 1.5, be more preferably less than 1.0. By the carboxymethyl cellulose (salt) using degree of etherification falling to be more than 0.4, it is possible to make to coat paste compound collector body first-class time workability good. When degree of etherification falling is lower than 0.4, due in the molecule of carboxymethyl cellulose (salt) and intermolecular hydrogen bond strong, therefore water-soluble thickener (B) can become gelling material. And then, when preparing paste compound, not easily obtain thickening effect, there is the hidden danger causing that workability time prepared by paste compound is deteriorated. Further, gained paste compound being coated on collector body and when forming cross-linked structure by cross-linking agent (D), carboxymethyl cellulose (salt) and cross-linking agent (D) are not susceptible to reaction, there is the hidden danger of the deterioration in characteristics causing the electrode obtained. It addition, be the carboxymethyl cellulose of less than 1.5 by using degree of etherification falling, the hydroxyl value of every 1 molecule carboxymethyl cellulose (salt) is sufficient, becomes good with the reactivity of cross-linking agent described later (D). Thus, carboxymethyl cellulose (salt) can form good cross-linked structure by cross-linking agent (D), therefore, as aftermentioned detailed description, negative pole can be made to close the caking property of each composition in sheet material layers by the formation of cross-linked structure good, it is possible to the cycle characteristics making secondary cell is excellent.

The degree of etherification falling of carboxymethyl cellulose (salt) refers to the meansigma methods of the number constituting the hydroxyl that be instead of by substituent groups such as carboxymethyls in the every Unit 1 of anhydrous glucose of carboxymethyl cellulose (salt). The desirable value more than 0 and less than 3 of degree of etherification falling of carboxymethyl cellulose (salt). Degree of etherification falling is more big, then it represents that the ratio of the hydroxyl in every 1 molecule of carboxymethyl cellulose (salt) reduces (that is, the ratio of substituent group increases); Degree of etherification falling is more little, then it represents that the ratio of the hydroxyl in every 1 molecule of carboxymethyl cellulose (salt) increases (that is, the ratio of substituent group reduces). This degree of etherification falling (substitution value) can be obtained by the method recorded in Japanese Unexamined Patent Publication 2011-34962 publication.

It addition, the viscosity of 1 mass % aqueous solution of carboxymethyl cellulose (salt) is preferably more than 500mPa s, is more preferably more than 1000mPa s, it is preferred to 10000mPa below s, be more preferably below 9000mPa s. The carboxymethyl cellulose (salt) that viscosity is more than 500mPa s of this aqueous solution when making 1 mass % aqueous solution by using, can make paste compound have the viscosity of appropriateness. Therefore, can make to coat this paste compound collector body first-class time workability good. It addition, by the carboxymethyl cellulose (salt) that viscosity is below 10000mPa s using 1 mass % aqueous solution, the viscosity of paste compound can be made to be held in desired low value. Its result, can make to coat paste compound collector body first-class time workability good, and, the adaptation between sheet material layers and collector body can be closed improve by the negative pole that obtains of use paste compound. The viscosity of 1 mass % aqueous solution of carboxymethyl cellulose (salt) be use Brookfield viscometer 25 DEG C, measure under rotating speed 60rpm time value.

As another preferred embodiment, water-soluble thickener (B) can be made to comprise carboxymethyl cellulose (salt) and polycarboxylic acids or its salt (being also abbreviated as " polycarboxylic acids (salt) " below). So, use carboxymethyl cellulose (salt) and polycarboxylic acids (salt) as water-soluble thickener (B) by combining, while the adaptation between sheet material layers and collector body of closing the negative pole that can obtain at use paste compound improves, the mechanical property such as intensity that the negative pole comprising water-soluble thickener (B) closes sheet material layers is made to improve. And then, it is possible to the cycle characteristics etc. of the secondary cell employing this negative pole is concomitantly improved with this. Here, as the polycarboxylic acids (salt) with carboxymethyl cellulose (salt) combination use, preferred alginic acid or its salt (being also abbreviated as " alginic acid (salt) " below) and polyacrylic acid or its salt (being also abbreviated as " polyacrylic acid (salt) " below), it is particularly preferred to polyacrylic acid (salt). Namely, it is particularly preferred to water-soluble thickener (B) comprises carboxymethyl cellulose or its salt and polyacrylic acid or its salt. This be due to, compared with polymethylacrylic acid etc., alginic acid, polyacrylic acid are not easily excessively swelling in the electrolyte of secondary cell, by in this wise carboxymethyl cellulose (salt) being used with alginic acid (salt) or polyacrylic acid (salt) combination, it is possible to fully improve the cycle characteristics of secondary cell. Additionally due also to, compared with carboxymethyl cellulose (salt), polyacrylic acid (salt) and cross-linking agent (D) can react well, if therefore using polyacrylic acid, then can promote that the formation of the cross-linked structure by cross-linking agent (D) is reacted.

In the paste compound of the present invention, when water-soluble thickener (B) comprises carboxymethyl cellulose (salt) and polycarboxylic acids (salt), in the summation of the use level of carboxymethyl cellulose (salt) and the use level of polycarboxylic acids (salt), the ratio shared by use level of polycarboxylic acids (salt) is preferably in given scope. The ratio shared by use level of described carboxymethyl cellulose (salt) is preferably more than 0.1 mass %, is more preferably more than 0.5 mass %, is particularly preferably more than 1 mass %, it is preferred to below 50 mass %, is more preferably below 35 mass %, is particularly preferably below 25 mass %. It is more than 0.1 mass % by making the ratio shared by the use level of polycarboxylic acids (salt), the effect used by carboxymethyl cellulose (salt) can be given full play of with polycarboxylic acids (salt) combination, therefore, it is possible to the negative pole improving use paste compound well and obtaining closes the adaptation between sheet material layers and collector body. Additionally, it is below 50 mass % by making the ratio shared by the use level of polycarboxylic acids (salt), the negative pole being not result in use paste compound and obtain closes sheet material layers and becomes really up to the mark, it can be ensured that negative pole closes the caking property between each composition contained in sheet material layers and ionic conductance. It addition, the negative pole that can improve this paste compound of use well and obtain closes the adaptation between sheet material layers and collector body.

The paste compound of the present invention is below more than 0.1 mass parts and 10 mass parts relative to the ratio of the water-soluble thickener (B) of active substance (A) 100 mass parts. It is preferably more than 0.5 mass parts relative to the ratio of the water-soluble thickener (B) of active substance (A) 100 mass parts, is more preferably more than 1.0 mass parts, it is preferred to below 5 mass parts, be more preferably below 3 mass parts. By making the use level of water-soluble thickener (B) in above-mentioned scope, it is possible to make the viscosity of paste compound reach appropriately sized, it is possible to make to coat paste compound collector body first-class time workability good. It addition, by with 100 mass parts every relative to negative electrode active material for ratio hydrous water soluble surfactant (B) more than 0.5 mass parts, it is possible to obtain good cycle characteristics. It addition, by with 100 mass parts every relative to negative electrode active material for ratio hydrous water soluble surfactant (B) below 5 mass parts, it is possible to reduce the resistance of the electrode obtained.

[1.3. particle shape binding agent (C)]

Particle shape binding agent (C) is able to the binding agent being scattered in the aqueous mediums such as water, exists with the form of particle in paste compound. Generally, for particle shape binding agent, when being dissolved in 100g water by particle shape binding agent 0.5g at 25 DEG C, insoluble component is more than 90 mass %.

When the paste compound using the present invention forms negative pole conjunction sheet material layers, particle shape binding agent (C) closes at negative pole and other composition (such as, active substance (A)) can be kept in sheet material layers not depart from from electrode member. Negative pole closes particle shape binding agent (C) in sheet material layers when impregnated in electrolyte, although Electolyte-absorptive and occur swelling, but emboliform shape can be kept, make active substance (A) be bonded to one another, can be shown that the function preventing active substance (A) from coming off from collector body. It addition, the particle that negative pole also can be closed beyond active substance (A) contained in sheet material layers by particle shape binding agent (C) also bonds, also give play to the effect of the intensity keeping negative pole conjunction sheet material layers.

In the paste compound of the present invention, it is below more than 0.1 mass parts and 0.5 mass parts relative to the ratio of particle shape binding agent (C) of active substance (A) 100 mass parts. It is preferably more than more than 0.4 mass parts, more preferably 1.0 mass parts relative to the ratio of particle shape binding agent (C) of active substance (A) 100 mass parts, on the other hand, it is preferable that lower than 3 mass parts, more preferably less than 2.5 mass parts, be further preferably shorter than 2 mass parts. By making the ratio of particle shape binding agent (C) in above-mentioned scope, it is possible to obtain the effect above. Particularly, the ratio of particle shape binding agent (C) is by more than above-mentioned lower limit, it is possible to improves negative pole and closes the peel property of sheet material layers, on the other hand, by below the above-mentioned upper limit, it is possible to improves the speed characteristic of battery.

[1.3.1. particle shape binding agent (C): the functional group reacted with cross-linking agent (D)]

Particle shape binding agent (C) preferably has the functional group reacted with cross-linking agent (D). More specifically, it is preferable that there is the functional group that the functional group's (such as carbodiimide) having with cross-linking agent (D) reacts. Particle shaped polymer (C) is by having the functional group reacted with cross-linking agent (D), it is possible to form particle shape binding agent (C) crosslinking to each other and between water-soluble thickener (B) and particle shape binding agent (C) by cross-linking agent (D).

The functional group reacted with cross-linking agent (D) that particle shape binding agent (C) can have can suitably be selected to the functional group of the functional group reactions having with cross-linking agent (D). Such as, when the functional group that cross-linking agent (D) has is carbodiimide, the concrete example of the functional group reacted with cross-linking agent (D) can having as particle shape binding agent (C), can enumerate: carboxyl, hydroxyl, glycidyl ether, thiol and their combination. Additionally, in the functional group that cross-linking agent (D) has beWhen known functional group's kinds such as azoles quinoline base, epoxy radicals and other NCO, can enumerate and these functional group reactionses, functional group that such as the known meeting such as carboxyl, hydroxyl, amide groups reacts. Wherein, from the view point of use the cycle characteristics of secondary cell that the paste compound of the present invention obtains, particle shape binding agent (C) preferably have any one in carboxyl, hydroxyl and thiol more than, it is preferred that at least one having in carboxyl and hydroxyl. Further, from the view point of take into account cycle characteristics and suppression that the negative pole with discharge and recharge expands, it is particularly preferred to particle shape binding agent (C) has carboxyl and hydroxyl.

Comprise the monomeric unit of the functional group reacted with cross-linking agent (D) by making particle shape binding agent (C) have, particle shape binding agent (C) can become the binding agent with the functional group reacted with cross-linking agent (D). The described monomeric unit comprising this functional group, is have the unit of structure that is aggregated by the monomer comprising this functional group and that obtain.

As the example of that can become the monomeric unit that comprises the functional group reacted with cross-linking agent (D), to comprise the functional group reacted with cross-linking agent (D) monomer, can enumerate: ethylenically unsaturated carboxylic acids monomeric unit, there is the unsaturated monomer unit of hydroxyl, there is the unsaturated monomer unit of glycidyl ether and there is the monomeric unit of thiol.

As the example of ethylenically unsaturated carboxylic acids monomer, can enumerate: the monocarboxylic acids such as acrylic acid, methacrylic acid .beta.-methylacrylic acid, maleic acid, fumaric acid, itaconic acid and dicarboxylic acids and its anhydride. Wherein, from the view point of the stability of the paste compound of the present invention, as ethylenically unsaturated carboxylic acids monomer, it is preferable that acrylic acid, methacrylic acid and itaconic acid. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

As the example of the unsaturated monomer with hydroxyl, can enumerate: double; two (2-hydroxyethyl) ester of acrylic acid 2-hydroxy methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxy propyl methacrylate, hydroxy butyl acrylate, methacrylic acid hydroxyl butyl ester, methacrylic acid 3-chlorine-2-hydroxyl propyl ester, two (ethylene glycol) maleate, two (ethylene glycol) itaconate, maleic acid 2-hydroxy methacrylate, maleic acid and fumaric acid 2-hydroxyethyl methyl ester. Wherein, it is preferable that acrylic acid 2-hydroxy methacrylate. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

As the example of the unsaturated monomer with glycidyl ether, can enumerate: glycidyl acrylate and glycidyl methacrylate. Wherein, it is preferable that glycidyl methacrylate. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

As the example of the monomeric unit with thiol, can enumerate: tetramethylolmethane four (3-mercaptobutylate), trimethylolpropane tris (3-mercaptobutylate) and trimethylolethane trimethacrylate (3-mercaptobutylate). Wherein, it is preferable that tetramethylolmethane four (3-mercaptobutylate). These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

The monomeric unit comprising the functional group reacted with cross-linking agent (D) is to have the unit of structure that is aggregated by the monomer comprising this functional group and that obtain, but is not limited to unit itself that is aggregated by the monomer comprising this functional group and that obtain.

Such as, can pass through after making the particle shape binding agent without the functional group reacted with cross-linking agent (D) be polymerized, by the functional moieties in this particle shape binding agent or be substituted by the functional group reacted with cross-linking agent (D) fully, thus importing the functional group reacted with cross-linking agent (D) in particle shape binding agent. By the operation of this replacement, it is possible to form the monomeric unit comprising the functional group reacted with cross-linking agent (D) in the polymer of constituent particle shape binding agent. In this wise, it is also possible to preparation comprises particle shape binding agent (C) of the functional group reacted with cross-linking agent (D).

The content ratio of the monomeric unit comprising the functional group reacted with cross-linking agent (D) in particle shape binding agent (C) is not particularly limited, but the upper limit is preferably below 10 mass %, is more preferably below 8 mass %, is particularly preferably below 5 mass %, on the other hand, lower limit is preferably more than 0.5 mass %, is more preferably more than 1.0 mass %, is particularly preferably more than 1.5 mass %. If the content ratio of above-mentioned monomer is in above-mentioned scope, then the mechanical stability of gained particle shape binding agent (C), chemical stability are excellent.

[1.3.2. particle shape binding agent (C): aliphatic conjugated diene monomer unit and aromatic vinyl monomer unit]

Particle shape binding agent (C) preferably has aliphatic conjugated diene monomer unit and aromatic vinyl monomer unit. Described aliphatic conjugated diene monomer unit is to have the unit of structure that is aggregated by aliphatic conjugated diene monomer and that obtain, and described aromatic vinyl monomer unit is to have the unit of structure that is aggregated by aromatic vinyl monomer and that obtain.

Aliphatic conjugated diene monomer unit is that rigidity is low and the repetitive of softness, it is possible to increase the caking property of particle shape binding agent (C). Aromatic vinyl monomer unit can make polymer dissolubility in the electrolytic solution reduce, thus improving particle shape binding agent (C) stability in the electrolytic solution. By having aliphatic conjugated diene monomer unit and aromatic vinyl monomer unit, the effect above of particle shape binding agent (C) can be demonstrated more well.

As the example of aliphatic conjugated diene monomer, can enumerate: 1,3-butadiene, 2-methyl isophthalic acid, 3-butadiene, 2,3-dimethyl-1,3-butadiene, chlorbutadiene, substituted straight chain conjugation pentadiene class and replacement and side chain conjugation hexadiene class, wherein, it is preferable that 1,3-butadiene. Aliphatic conjugated diene monomer can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

The content ratio of the aliphatic conjugated diene monomer unit in particle shape binding agent (C) is preferably more than 20 mass %, is more preferably more than 30 mass %, it is preferred to below 70 mass %, is more preferably below 60 mass %, is particularly preferably below 55 mass %. By making the content ratio of aliphatic conjugated diene monomer unit be more than 20 mass %, the flexibility of negative pole can be improved, additionally, by for below 70 mass %, the adaptation that negative pole closes between sheet material layers and collector body can be made good, and it is possible to improve the electrolyte resistance of the negative pole using the paste compound of the present invention to obtain.

As the example of aromatic vinyl monomer, can enumerate: styrene, ��-methyl styrene, vinyltoluene and divinylbenzene, wherein optimization styrene. Aromatic vinyl monomer can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

The content ratio of the aromatic vinyl monomer unit in particle shape binding agent (C) is preferably more than 30 mass %, is more preferably more than 35 mass %, it is preferred to below 79.5 mass %, be more preferably below 69 mass %. By making the content ratio of aromatic vinyl monomer unit be more than 30 mass %, the electrolyte resistance of the negative pole using the paste compound of the present invention to obtain can be improved, by for below 79.5 mass %, it is possible to make the adaptation that negative pole closes between sheet material layers and collector body good.

In particular it is preferred that particle shape binding agent (C) comprises 1,3-butadiene unit as aliphatic conjugated diene monomer unit, comprise styrene units as aromatic vinyl monomer unit (that is, SB).

[1.3.3. particle shape binding agent (C): other unit]

It addition, in the scope of effect significantly not destroying the present invention, particle shape binding agent (C) can also comprise any repetitive than that described above. As the monomer corresponding with above-mentioned any repetitive, can enumerate such as: vinyl cyanide base class monomer, unsaturated carboxylic acid alkyl ester monomer, unsaturated carboxylic acid amide monomer etc. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

As the example of vinyl cyanide base class monomer, can enumerate: acrylonitrile, methacrylonitrile, ��-chloro-acrylonitrile, ��-ethyl acrylonitrile etc. Wherein, it is preferable that acrylonitrile, methacrylonitrile. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

As the example of unsaturated carboxylic acid alkyl ester monomer, can enumerate: acrylic acid methyl ester., methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, dimethyl fumarate, DEF, dimethyl maleate, ethyl maleate., dimethyl itaconate, monomethyl fumarate, monomethyl ester, 2-EHA etc. Wherein, it is preferable that methyl methacrylate. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

As the example of unsaturated carboxylic acid amide monomer, can enumerate: acrylamide, Methacrylamide, N hydroxymethyl acrylamide, N-methylol methacrylamide, N,N-DMAA etc. Wherein, it is preferable that acrylamide, Methacrylamide. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

Further, particle shape binding agent (C) can also use the monomer that such as ethylene, propylene, vinyl acetate, propionate, vinyl chloride, vinylidene chloride etc. use in conventional emulsion polymerization to manufacture. These monomers can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

In particle shape binding agent (C) except aliphatic conjugated diene monomer unit, aromatic vinyl monomer unit, comprise the functional group reacted with cross-linking agent (D) monomeric unit except the content ratio of other monomeric unit be not particularly limited, but the upper limit is preferably below 10 mass % with total amount, is more preferably below 8 mass %, is particularly preferably below 5 mass %, on the other hand, lower limit is preferably more than 0.5 mass %, is more preferably more than 1.0 mass %, is particularly preferably more than 1.5 mass %.

[preparation of 1.3.4. particle shape binding agent (C)]

Particle shape binding agent (C) such as can be prepared by making the monomer composition comprising above-mentioned monomer carry out being polymerized in aqueous solvent.

Here, in monomer composition, the content ratio of each monomer is generally identical with the content ratio of the repetitive in desired particle shape binding agent (C).

As long as aqueous solvent can make particle shape binding agent (C) be not particularly limited with the scattered solvent of particle state, can be generally usual more than 80 DEG C, preferably more than 100 DEG C from the boiling point normal pressure, the aqueous solvent of usual less than 350 DEG C, preferably less than 300 DEG C selects.

Specifically, as aqueous solvent, can enumerate such as: water; The ketone such as DAA, gamma-butyrolacton; The alcohols such as ethanol, isopropanol, normal propyl alcohol; The glycol ethers such as propylene glycol monomethyl ether, methyl cellosolve, ethyl cellosolve, ethylene glycol tertbutyl ether, butyl cellosolve, MMB, ethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl base ether, DPGME; The ethers such as 1,3-dioxolane, 1,4-dioxolane, oxolane; Etc.. Wherein, the viewpoint of the dispersion never have combustibility, being readily available the particle of particle shape binding agent (C) is set out, it is particularly preferred to water. Main solvent can also be used water as, in the scope being able to ensure that the dispersity of particle of particle shape binding agent (C), mix the aqueous solvent beyond above-mentioned water.

Polymerization is not particularly limited, and can adopt any means in such as solution polymerization process, suspension polymerization, mass polymerization, emulsion polymerization etc. As polymerization, arbitrary method in such as ionic polymerization, radical polymerization, active free radical polymerization etc. also can be adopted. From the view point of manufacture efficiency, it is particularly preferred to emulsion polymerization. According to emulsion polymerization, the advantage that manufacture efficiency aspect as described below can be obtained: be readily obtained high molecular body; And polymer can directly state to be scattered in water obtain, therefore it is made without the process of redispersion, it is possible to be directly used in the manufacture etc. of the paste compound of the present invention.

Emulsion polymerization can conventionally carry out.

It addition, for the emulsifying agent used in polymerization, dispersant, polymerization initiator, reagent and additive in polymerization etc., can use generally adopted those, it makes consumption also for normally used amount. It addition, when polymerization, it is possible to adopt seed particles to carry out seeding polymerization. It addition, polymerizing condition arbitrarily can also select according to the kind of polymerization and polymerization initiator etc. Here, in the present invention, from the view point of avoid the consumption of cross-linking agent (D), it is preferable that the low-molecular-weight oligomer composition in the monomer component of the residual contained by reducing in this particle shape binding agent (C) and polymerization. Such as, polymerization initiator generally speaking relative to polymerization single polymerization monomer 100 mass parts less than 3 mass parts, but in the present invention, it is preferred to be below below 2 mass parts, more preferably 1.5 mass parts. Equally, polymerization temperature is generally speaking lower than 80 DEG C, but in the present invention, it is preferred to lower than 70 DEG C, is even more preferably below 60 DEG C. Time in this scope, it is intended in the growth response being maintained with polymer suppressing polymerization speed, therefore, it is possible to the low-molecular-weight oligomer composition reduced in monomer component and polymerization.

For utilizing the aqueous dispersion of the particle of particle shape binding agent (C) that above-mentioned polymerization obtains, can directly or as desired after pH regulator and refining operation, using as the compositions (CX) comprising particle shape binding agent (C) in the manufacture method of the paste compound of the present invention. The pH of compositions (CX) can use alkaline aqueous solution to adjust to usual more than 5, the usual scope of less than 10, preferably less than 9. As the example of the material comprised in alkaline aqueous solution, can enumerate: the hydroxide of alkali metal (such as, Li, Na, K, Rb, Cs), ammonia, Inorganic Ammonium compound (such as NH₄Cl etc.) and organic amine compound (such as ethanolamine, diethylamine etc.). Wherein, utilize the pH that alkali metal hydroxide carries out to adjust and the adaptation between collector body and negative pole conjunction sheet material layers can be made to improve, therefore preferably.

[character of 1.3.5. particle shape binding agent (C)]

Generally, particle shape binding agent (C) is for water-insoluble. Therefore, generally, particle shape binding agent A becomes particle shape in the paste compound of the present invention, and keeps the state of its shape of particle to be present in the negative pole conjunction sheet material layers of such as secondary battery cathode.

In the paste compound of the present invention, the number average bead diameter of particle shape binding agent (C) is preferably more than 50nm, is more preferably more than 70nm, it is preferred to below 500nm, be more preferably below 400nm. By making number average bead diameter in above-mentioned scope, it is possible to make the intensity of gained negative pole and flexibility good. Number average bead diameter can be passed through transmission electron microscopy, coulter counter, laser diffraction and scattering method etc. and be easily determined by.

The gel content of particle shape binding agent (C) is preferably more than 50 mass %, is more preferably more than 80 mass %, it is preferred to below 98 mass %, be more preferably below 95 mass %. When the gel content of particle shape binding agent (C) is lower than 50 mass %, exists and cause that the cohesiveness of particle shape binding agent (C) reduces, become insufficient hidden danger with the adaptation of collector body etc. On the other hand, when the gel content of particle shape binding agent (C) is more than 98 mass %, the toughness that there is particle shape binding agent (C) disappears and becomes fragile, results in the hidden danger that adaptation becomes insufficient.

In the present invention, " gel content " of particle shape binding agent (C) can use the assay method recorded in the embodiment of this specification to be measured.

The glass transition temperature (Tg) of particle shape binding agent (C) is preferably more than-30 DEG C, is more preferably more than-20 DEG C, it is preferred to less than 80 DEG C, be more preferably less than 30 DEG C. By making the glass transition temperature of particle shape binding agent (C) be more than-30 DEG C, can prevent the gradation composition in the paste compound of the present invention from occurring cohesion to settle, it is ensured that the stability of paste compound. And it is possible to suppress the expansion of negative pole aptly. It addition, be less than 80 DEG C by making the glass transition temperature of particle shape binding agent (C), it is possible to make to coat the paste compound of the present invention collector body first-class time workability good.

In the present invention, " glass transition temperature " of particle shape binding agent (C) can use the assay method recorded in the embodiment of this specification to be measured.

The glass transition temperature of particle shape binding agent (C) and gel content can pass through to change the preparation condition (monomer that such as, uses, polymerizing condition etc.) of particle shape binding agent (C) and suitably adjust.

Glass transition temperature can be adjusted by the kind and amount changing the monomer used, such as, if using the monomer such as styrene, acrylonitrile, then glass transition temperature can be improved, if using the monomer such as butyl acrylate, butadiene, then glass transition temperature can be made to reduce.

Additionally, gel content can be adjusted by the conversion ratio etc. when changing polymerization temperature, the kind of polymerization initiator, the kind of molecular weight regulator, amount, reaction terminating, such as, if minimizing chain-transferring agent, then can improve gel content, if increasing chain-transferring agent, then gel content can be made to reduce.

[1.4. cross-linking agent (D)]

Cross-linking agent (D) is the composition as paste compound and water-soluble thickener (B) and particle shape binding agent (C) coexist, and using paste compound to be formed can to pass through when negative pole closes sheet material layers the composition process such as being heated and form cross-linked structure between water-soluble thickener (B) and particle shape binding agent (C). Specifically, cross-linking agent (D) can at the molecule of water-soluble thickener (B) to each other, between water-soluble thickener (B) and particle shape binding agent (C) and the particle of particle shape binding agent (C) to each other in any one cross-linked structure formed above. As cross-linking agent (D), it may be preferable to use the cross-linking agent that at least can form cross-linked structure at the particle of particle shape binding agent (C) to each other.

Close in sheet material layers at negative pole, by being formed crosslinking by cross-linking agent (D), the mechanical properties such as elastic modelling quantity, tensile break strength, fatigue durability can be obtained and the negative pole with cross-linked structure of the excellent in adhesion of collector body and the dissolubility in water little (i.e. excellent water resistance) is closed sheet material layers.

Therefore, when the paste compound of the present invention being used for the preparation of negative pole, by forming cross-linked structure, it is possible to while the negative pole suppressing to occur with repeated charge expands, it is ensured that negative pole closes the high adhesion between sheet material layers and collector body. It is as a result, it is possible to make the cycle characteristics etc. of secondary cell improve.

In the paste compound of the present invention, it is below more than 0.01 mass parts and 5 mass parts relative to the ratio of the cross-linking agent (D) of active substance (A) 100 mass parts. It is preferably more than 0.02 mass parts relative to the ratio of the cross-linking agent (D) of active substance (A) 100 mass parts, is more preferably more than 0.025 mass parts, is further preferably 0.03 mass parts, on the other hand, it is preferable that lower than 3 mass parts, more preferably less than 1 mass parts, be further preferably shorter than 0.5 mass parts. By making the ratio of cross-linking agent (D) in above-mentioned scope, it is possible to obtain the effect above. Particularly, by making the ratio of cross-linking agent (D) in above-mentioned scope, it is possible to increase negative pole closes the peel property of sheet material layers, further, it is possible to reduce the thickness change caused by absorbing water.

[1.4.1. cross-linking agent (D): structure]

Cross-linking agent (D) can have the various structures that can form crosslinking. As its example, it is possible to be every a part structure with more than 2 reactive functional groups. As the example of such functional group, can enumerate: epoxy radicals,Azoles quinoline base and carbodiimide. Such as, as the cross-linking agent with epoxy radicals, multi-functional epoxy compound can be enumerated. As such concrete example, can enumerate: polyfunctional glycidyl ether's compounds such as aliphatic polyglycidyl ether, aromatic series polyglycidyl ether, diglycidyl ether. As havingThe compound of azoles quinoline base, specifically can enumerate such as: 2,2'-double; two (2-Azoles quinoline), the double; two (4-methyl-2-of 2,2'-Azoles quinoline), the double; two (4,4-dimethyl-2-of 2,2'-Azoles quinoline), the double; two (4-ethyl-2-of 2,2'-Azoles quinoline), the double; two (4,4'-diethyl-2-of 2,2'-Azoles quinoline), the double; two (4-propyl group-2-of 2,2'-Azoles quinoline), the double; two (4-butyl-2-of 2,2'-Azoles quinoline), the double; two (4-hexyl-2-of 2,2'-Azoles quinoline), the double; two (4-phenyl-2-of 2,2'-Azoles quinoline), the double; two (4-cyclohexyl-2-of 2,2'-Azoles quinoline), the double; two (4-benzyl-2-of 2,2'-Azoles quinoline) etc. Furthermore it is also possible to enumerate the cross-linking agent of the polymer electrolytes such as Japan catalyst (strain) EPOCROS processed (trade (brand) name). It addition, as other preference, cross-linking agent (D) can have every 1 molecule and have the structure of more than 2 carbodiimides.

As the example of the structure of the cross-linking agent (D) with carbodiimide, can enumerate in molecule and there is formula (1) :-N=C=N-... the structure of the carbodiimide shown in (1). By having a structure in which, it is possible to the carboxyl etc. having with water-soluble thickener (B) and/or particle shape binding agent (C) reacts and forms crosslinking.

More specifically example as the structure of the cross-linking agent (D) with carbodiimide, the compound with more than 2 carbodiimides can be enumerated, as further specific example, it may be preferable to enumerate: there is formula (2) :-N=C=N-R¹-... (2) (in formula (2), R¹Represent the organic group of divalent) shown in the poly-carbodiimide of repetitive and/or modified poly-carbodiimide. In this specification, described modified poly-carbodiimide refers to, the resin obtained by making reactive compounds described later react relative to poly-carbodiimide.

[1.4.2. cross-linking agent (D): the synthesis of poly-carbodiimide]

The synthetic method of poly-carbodiimide is not particularly limited, for instance can pass through to make organic multiple isocyanate react under the existence promoting the catalyst (hereinafter referred to as " carbodiimidization catalyst ") of carbodiimidization reaction of NCO and synthesize poly-carbodiimide. It addition, have the repetitive shown in formula (2) poly-carbodiimide can also by make organic multiple isocyanate reaction and the oligomer (carbodiimide oligomer) that obtain with can and the monomer of this oligomer copolymerization carry out copolymerization and synthesize.

As the organic multiple isocyanate used in the synthesis of this poly-carbodiimide, it is preferable that organic diisocyanate.

As the organic diisocyanate used in the synthesis of poly-carbodiimide, the organic diisocyanate such as recorded in Japanese Unexamined Patent Publication 2005-49370 publication can be enumerated. Wherein, as cross-linking agent (D), from the view point of comprise the storage stability of the paste compound of poly-carbodiimide, it is particularly preferred to 2,4 toluene diisocyanate, 2,6-toluene di-isocyanate(TDI)s. Organic diisocyanate can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

Additionally, can also while using above-mentioned organic diisocyanate, use the organic multiple isocyanate (3 officials can organic multiple isocyanate) above with more than 3 NCOs, by 3 officials excessive in stoichiometry can above organic multiple isocyanate and 2 officials can the above multi-functional compound containing active hydrogenation reacted and obtain terminal isocyanate prepolymer (below, by above-mentioned 3 officials can above organic multiple isocyanate and above-mentioned end isocyanate prepolymer be referred to as " 3 officials can organic multiple isocyanate class " above). As such 3 officials can above organic multiple isocyanate class, those that such as record in Japanese Unexamined Patent Publication 2005-49370 publication can be enumerated. 3 officials organic multiple isocyanate class above can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine. With regard to 3 officials in the synthetic reaction of poly-carbodiimide can above organic multiple isocyanate class make consumption for, relative to organic diisocyanate 100 mass parts, be generally below 40 mass parts, be preferably below 20 mass parts.

Further, when the poly-carbodiimide of synthesis, it is also possible to add organic single-isocyanate as desired. By adding organic single-isocyanate, 3 officials can be contained at organic multiple isocyanate and can suitably limit the molecular weight of gained poly-carbodiimide when above organic multiple isocyanate class, additionally, by organic diisocyanate is used with organic single-isocyanate combination, it is possible to obtain the poly-carbodiimide of molecular weight. As such organic single-isocyanate, those that record in such as Japanese Unexamined Patent Publication 2005-49370 publication can be enumerated. Organic single-isocyanate can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine. With regard in the synthetic reaction of poly-carbodiimide organic single-isocyanate make consumption for, also rely on the poly-molecular weight required by carbodiimide of gained, whether use 3 officials can above organic multiple isocyanate class etc., but relative to whole organic multiple isocyanates (organic diisocyanate and 3 officials can organic multiple isocyanate class) above every 100 mass parts of composition, it is generally below 40 mass parts, is preferably below 20 mass parts.

It addition, as carbodiimidization catalyst, phospholene (phospholene) compound, Metal carbonyl complex, the acetylacetonate complex of metal, phosphate ester can be enumerated. Their concrete example is disclosed respectively in such as Japanese Unexamined Patent Publication 2005-49370 publication. Carbodiimidization catalyst can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine. Carbodiimidization catalyst make consumption relative to whole organic isocyanates (organic single-isocyanate, organic diisocyanate and 3 officials can organic multiple isocyanate class) above every 100 mass parts of composition, it is generally more than 0.001 mass parts, is preferably more than 0.01 mass parts, below usual 30 mass parts, be preferably below 10 mass parts.

The carbodiimidization reaction of organic multiple isocyanate can in solvent-free lower enforcement, it is also possible to implements in suitable solvent. As solvent when implementing synthetic reaction in a solvent, it does not have particular determination, the solvent that can dissolve poly-carbodiimide or the carbodiimide oligomer generated because of the heating in synthetic reaction can be used. As its example, can enumerate: halogenated hydrocarbon solvent, ether solvent, ketones solvent, aromatic hydrocarbon solvent, amide solvent, polar non-solute, acetate esters solvent. Their concrete example is disclosed respectively in such as Japanese Unexamined Patent Publication 2005-49370 publication. These solvents can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine. With regard to the solvent in the synthetic reaction of poly-carbodiimide make consumption for, be the amount that concentration is usual more than 0.5 mass %, preferably more than 5 mass %, usual below 60 mass %, preferably below 50 mass % making whole organic isocyanate composition. If the concentration of the whole organic isocyanate compositions in solvent is too high, then existence causes that the hidden danger of gelation occurs in synthetic reaction for the poly-carbodiimide generated or carbodiimide oligomer, additionally, if the concentration of the whole organic isocyanate compositions in solvent is too low, then causing that response speed is slack-off, productivity declines.

The temperature of the carbodiimidization reaction of organic multiple isocyanate suitably can select according to organic isocyanate composition, the kind of carbodiimidization catalyst, but is generally more than 20 DEG C and less than 200 DEG C. When the carbodiimidization carrying out organic multiple isocyanate reacts, for organic isocyanate composition, it is possible to add whole amount before the reaction, or, it is also possible to add it in the reaction continuously or by stages part or all of. Additionally, in the present invention, the suitable stage of reaction in the initial stage to later stage reacted from the carbodiimidization of organic multiple isocyanate can also add the compound that can react with NCO, close the terminal isocyanate group of poly-carbodiimide, thus regulating the molecular weight of the poly-carbodiimide of gained. Furthermore it is also possible to add in the later stage that the carbodiimidization of organic multiple isocyanate reacts, thus the molecular weight by poly-for gained carbodiimide is limited to set-point. As such compound that can react with NCO, can enumerate such as: the alcohols such as methanol, ethanol, isopropanol, Hexalin; The amines such as dimethylamine, diethylamine, benzylamine.

Additionally, as can with the monomer of carbodiimide oligomer copolymerization, preferably more than 2 yuan alcohol, the oligomer using the alcohol of more than 2 yuan to obtain as monomer and ester thereof, for instance: 2 yuan of alcohol such as ethylene glycol, propylene glycol or polyoxyalkylene, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, polyethylene glycol monoacrylate, polypropylene glycol mono acrylic ester.

By such as utilizing known method to make two ends of strand have 2 yuan of alcohol of hydroxyl and carbodiimide oligomer copolymerization, it is possible to synthesis has poly-carbodiimide and is derived from the poly-carbodiimide of monomeric unit of 2 yuan of alcohol. So, when the poly-carbodiimide as cross-linking agent (D) has the monomeric unit of the alcohol being derived from more than 2 yuan, preferably has the monomeric unit being derived from 2 yuan of alcohol, the negative pole that formed by the paste compound comprising this poly-carbodiimide wettability relative to electrolyte can be improved, make to possess the fluid injection of electrolyte in the manufacture of the secondary cell of this battery components and improve. Additionally, if the alcohol that copolymerization is above-mentioned, then the water solublity of poly-carbodiimide can be made to increase, simultaneously, poly-carbodiimide can occur, from micellization (taking the structure covered by hydrophilic glycol chain around hydrophobic carbodiimide), therefore can improve chemical stability in water.

Above-mentioned poly-carbodiimide can as a solution or with the preparation for the paste compound of the present invention of the form of solid isolated from solution. As the method making poly-carbodiimide separate from solution, can enumerate such as: poly-Carbodiimide solution is added to relative in this inactive poor solvent of poly-carbodiimide, and by filtering or decant and the method that produced precipitate or grease is easily separated, gathers; The method be easily separated by spray drying, gathered; The changes in solubility utilized at different temperatures in the solvent of the synthesis for the poly-carbodiimide of gained and the method being easily separated, gathering, namely, when just synthesizing the poly-carbodiimide being dissolved in this solvent afterwards and can precipitate out by reducing system temperature, the method etc. being easily separated from its dirty solution, gathering is waited by filtering, further, it is also possible to these are separated and acquisition method is appropriately combined carries out. The polystyrene conversion number-average molecular weight (hereinafter referred to as " Mn ") that gel permeation chromatography (GPC) is obtained that utilizes of the poly-carbodiimide in the present invention is generally more than 400, is preferably 1, more than 000, it is particularly preferably 2, more than 000, it is generally 500, less than 000, it is preferably 200, less than 000, it is particularly preferably less than 100,000.

[1.4.3. cross-linking agent (D): the synthesis of modified poly-carbodiimide]

Then, the example for the synthetic method of modified poly-carbodiimide illustrates. Modified poly-carbodiimide can pass through at least one of poly-carbodiimide making to have the repetitive shown in formula (2) with at least one of reactive compounds under the existence of suitable catalyst or when being absent from catalyst, under proper temperature, react (hereinafter referred to as " modified-reaction ") synthesize.

Reactive compounds for the synthesis of modified poly-carbodiimide refers to have 1 in its molecule and have reactive group (hereinafter referred to as " reactive group ") with poly-carbodiimide and have the compound of other functional group further. This reactive compounds can be aromatic compound, aliphatic compound or alicyclic compound, it addition, the ring structure in aromatic compound and alicyclic compound can be carbocyclic ring can also be heterocycle. As the example of the reactive group in reactive compounds, the group with activation hydrogen can be enumerated, specifically can enumerate: carboxyl or primary amino radical or secondary amino group. And then, in the molecule of reactive compounds except there is 1 reactive group, it is also possible to there is other functional group further. As other functional group that reactive compounds has, also can comprise have promote the 2nd in poly-carbodiimide and/or the modified poly-group of effect of cross-linking reaction of carbodiimide, reactive compounds 1 molecule later (namely, be different from above-mentioned reactive group other) the above-mentioned group with activation hydrogen, such as, except acid anhydride and tertiary amino, also can enumerate the carboxyl and primary amino radical or secondary amino group etc. that illustrate as having the group activating hydrogen. As these other functional groups, reactive compounds 1 molecule can exist more than 2 identical or different groups.

As reactive compounds, those that such as record in Japanese Unexamined Patent Publication 2005-49370 publication can be enumerated. Wherein, it is preferable that trimellitic anhydride, nicotinic acid. Reactive compounds can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

For in the modified-reaction of the poly-carbodiimide of synthesis modification reactive compounds make consumption, physical property required by poly-carbodiimide etc. can be modifiied according to poly-carbodiimide and the kind of reactive compounds, gained and suitably regulate. For the amount of being preferably used of reactive compounds, relative to the repetitive 1 mole shown in the formula (2) of poly-carbodiimide, reactive compounds make consumption be make the ratio of the reactive group in reactive compounds be preferably more than 0.01 mole it is preferred that it is preferred that the amount of less than 0.8 mole below more than 0.02 mole, preferably 1 mole. When aforementioned proportion is lower than 0.01 mole, it is possible to cause that the storage stability of the paste compound comprising modified poly-carbodiimide declines. On the other hand, when aforementioned proportion is more than 1 mole, it is possible to the characteristic causing poly-carbodiimide intrinsic is impaired.

Additionally; in modified-reaction; the reaction of the repetitive shown in formula (2) of the reactive group in reactive compounds and poly-carbodiimide would generally carry out quantitatively, has the functional group making consumption match with this reactive compounds to be directed in modified poly-carbodiimide. Modified-reaction also is able to implement under condition of no solvent, but implements preferably in suitable solvent. Such solvent is not particularly limited, it is possible to be relative to poly-carbodiimide and reactive compounds torpescence and the solvent that can they be dissolved. As its example, can enumerate and can be used in the ether solvent of synthesis of above-mentioned poly-carbodiimide, amide solvent, ketones solvent, aromatic hydrocarbon solvent, polar non-solute etc. These solvents can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine. It addition, use when can be used in synthesizing poly-carbodiimide in modified-reaction solvent time, it is also possible to directly use by its poly-Carbodiimide solution being synthesized into. With regard to the solvent in modified-reaction make consumption for, 100 mass parts every relative to the total amount of reaction raw materials, be generally more than 10 mass parts, be preferably more than 50 mass parts, be generally below 10,000 mass parts, be preferably below 5,000 mass parts. The temperature of modified-reaction suitably can select according to poly-carbodiimide, the kind of reactive compounds, but is generally more than-10 DEG C, is generally less than 100 DEG C, is preferably less than 80 DEG C. The Mn of the modified poly-carbodiimide in the present invention is generally more than 500, is preferably more than 1,000, more preferably more than 2,000, is generally less than 1,000,000, is preferably less than 400,000, more preferably less than 200,000.

[character etc. of 1.4.4. cross-linking agent (D)]

The formula weight (NCN equivalent) corresponding to every 1 mole of carbodiimide (-N=C=N-) for the cross-linking agent (D) of the present invention is preferably more than 300, is more preferably more than 400, it is preferred to less than 600, be more preferably less than 500. By making the NCN equivalent of cross-linking agent (D) be more than 300, it is possible to substantially ensure that the storage stability of the paste compound of the present invention, by for less than 600, it is possible to make cross-linking reaction carry out well as cross-linking agent.

The NCN equivalent of cross-linking agent (D) can be obtained as follows: such as, gel permeation chromatography (GPC) is utilized to obtain the polystyrene conversion number-average molecular weight of carbodiimide compound, utilize the quantity of carbodiimide in the every 1 molecular carbon diimine compounds of IR (infrared measure) quantitative analysis simultaneously, and adopt following formula to be calculated.

NCN equivalent=(the polystyrene conversion number-average molecular weight of carbodiimide compound)/(quantity of the carbodiimide in every 1 molecular carbon diimine compounds)

It addition, the viscosity of 1 mass % aqueous solution of cross-linking agent (D) is preferably below 5000mPa s, is more preferably below 700mPa s, is particularly preferably below 150mPa s. By using the viscosity of the 1 mass % aqueous solution cross-linking agent in above-mentioned scope, it is possible to make negative pole close the excellent adhesion between sheet material layers and collector body. The method that the viscosity of 1 mass % aqueous solution of cross-linking agent (D) can utilize the viscosity of the 1 mass % aqueous solution with above-mentioned carboxymethyl cellulose (salt) same is measured. The lower limit of the viscosity of 1 mass % aqueous solution of cross-linking agent (D) is not particularly limited, for instance can be more than 10mPa s.

It addition, cross-linking agent (D) is preferably water solublity. By making cross-linking agent (D) be water solublity, it is possible to prevent cross-linking agent (D) in paste compound from existing unevenly, so that gained negative pole closes sheet material layers forms suitable cross-linked structure. Therefore, it is possible to while negative pole in guaranteeing gained secondary cell closes the dhering strength between sheet material layers and collector body, make cycle characteristics improve, and suppress the impedance rising after circulation. And then, it is possible to make the resistance to water of negative pole improve.

Here, in this manual, cross-linking agent refers to for " water solublity ": when making to comprise the specific sample of cross-linking agent and water by the sieve of 250 orders, does not pass through sieve and remains in the quality of the solid constituent of residue on the sieve solid constituent relative to the cross-linking agent added less than 50 mass %.

Here, specific sample is that 100 mass parts every relative to ion exchange water are added cross-linking agent 1 mass parts (with the suitable gauge of solid constituent) the mixture that is stirred and obtains, adjusts to the scope of temperature more than 20 DEG C and less than 70 DEG C and the sample of at least one condition in condition in scope that pH is more than 3 and less than 12 (use NaOH aqueous solution and/or HCl/water solution are to adjust pH).

Even if the mixture of above-mentioned cross-linking agent and water is the emulsion state being separated into two-phase when standing, as long as meeting above-mentioned definition, namely think that this cross-linking agent is water solublity. From the view point of make the reaction that formed of cross-linked structure carry out well, make above-mentioned negative pole close the dhering strength between sheet material layers and collector body, cycle characteristics raising, more preferably the mixture of above-mentioned cross-linking agent and water is not separated into two-phase (single-phase water-soluble state), that is, more preferably cross-linking agent is single-phase water dissolubility.

[1.5. water and other solvent]

The paste compound of the present invention comprises water. Water in paste compound as solvent or disperse medium function. Generally, in the paste compound of the present invention, water-soluble thickener (B) is dissolved in water, and particle shape binding agent (C) is scattered in water.

In the paste compound of the present invention, as solvent, it is also possible to the solvent beyond water is used with water combination, but from the view point of avoid and the reaction of cross-linking agent (D), it is preferable that substantially do not comprise the solvent beyond water.

The amount of the solvent in the paste compound of the present invention is preferably configured so that the solid component concentration of paste compound and drops on desired scope. The solid component concentration of concrete paste compound is preferably more than 10 mass %, is more preferably more than 15 mass %, is particularly preferably more than 20 mass %, it is preferred to below 80 mass %, is more preferably below 75 mass %, is particularly preferably below 70 mass %. Here, the solid constituent of described compositions refers to, the material remained through the dry of said composition.

[any composition of 1.6.: cellulose nano-fibrous]

In the paste compound of the present invention, except mentioned component, it is possible to cellulose nano-fibrous containing as any composition. Cellulose nano-fibrous be utilize the methods such as mechanical fibrillation to carry out fibrillation the cellulose fibres such as the cellulose fibre of plant origin and obtain the fiber diameter fiber less than 1 ��m. Fiber diameter is preferably below 100nm, on the other hand, it is preferred to more than 1nm. As cellulose nano-fibrous, goods such as " CELISH (registered trade mark) KY-100G " (Daicel chemical industrial company systems) specifically can be used such as. Cellulose nano-fibrous by making paste compound comprise, it is possible to realize the raising of cycle characteristics and the reduction of impedance more well.

When the paste compound of the present invention comprises cellulose nano-fibrous, the paste compound of the present invention is preferably more than 0.1 mass parts relative to the cellulose nano-fibrous ratio of particle shape binding agent (C) 100 mass parts, is more preferably more than 0.5 mass parts, on the other hand, it is preferred to below 10.0 mass parts, be more preferably below 5.0 mass parts. By reaching the ratio within the scope of this, it is possible to realize the raising of cycle characteristics and the reduction of impedance more well.

[other composition of 1.7.]

In the slurry for secondary battery electrode compositions of the present invention except mentioned component, it is also possible to containing compositions such as conductive agent, supporting material, levelling agent, electrolysis additives. As long as cell reaction will not be impacted by these compositions, it is not particularly limited, the material recorded in known material, such as International Publication No. 2012/115096th number can be used. These compositions can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

[ratio of 1.8. oligomer composition]

In the paste compound of the present invention, relative to all solids composition of paste compound, the ratio utilizing the composition of molecular weight less than 3000 in the paste compound that gel permeation chromatography (GPC) measures is below 0.10 mass %. Hereinafter, also by this specific composition referred to as " oligomer composition ".

Oligomer composition like this, its overwhelming majority comes from the oligomer that the degree of polymerization produced when preparing polymer is low. Oligomer becomes branch react with cross-linking agent (D) and consume cross-linking agent (D). Therefore, if such oligomer composition exists in large quantities, then can cause that the amount being supplied in the cross-linking agent (D) of the crosslinking of the material that the needs such as particle shape binding agent (C) carry out cross-linking relatively reduces. In this case, if adding cross-linking agent in large quantities to demonstrate the effect of cross-linking agent, then it is likely to cause that peel strength reduction, speed characteristic, the such characteristic of cycle characteristics decline on the contrary.

The unreacted monomer of remaining during about polymerization, in the prior art also can for avoiding the reasons such as undesirable reaction to remove by heating decompression distillation. But the present inventor finds according to research, even if when having carried out such distillation, cross-linking agent (D) is still more consumed. And also find, one of its reason is in that, molecular weight is high thus oligomer that boiling point is higher, more is difficult to remove by distilling. Therefore, by making the low value that ratio is below special ratios as above of oligomer composition, even if the addition of cross-linking agent (D) is the effect also being able to fully obtain cross-linking agent (D) on a small quantity, its result, it is obtained in that the characteristics such as high peel property, low water absorbable, and then speed characteristic and cycle characteristics can be made to improve.

The upper limit of the oligomer component amount in the paste compound of the present invention is preferably shorter than 0.05 mass %, more preferably less than 0.03 mass parts. On the other hand, lower limit is preferably 0 mass %.

Utilize that GPC carries out, can carry out as described below relative to the mensuration of ratio of the oligomer composition of all solids composition of paste compound. Weigh paste compound and be about 5g, in 60 DEG C dry 20 minutes, in 110 DEG C dry 20 minutes, in 60 DEG C of vacuum driers dry 10 hours further, measure dried quality, and obtained solid component concentration (W0) by its difference. Paste compound is being about while 5g utilizes centrifugal separator (Kokusan company system, trade name: cooling high speed centrifuge (H-2000B)) to be cooled to 5 �� 1 DEG C, carry out centrifugation in 10 minutes operation at ambient pressure, with 7000rpm, gather its supernatant. Then, make supernatant after 60 DEG C of vacuum dryings 10 hours, implement the separation of the molecular weight determination based on preparative gel permeation chromatography (GPC) method and each composition, obtain (divide and take) and quality determination respectively.

Specifically, molecular weight is obtained as follows: after being dissolved in oxolane and make 0.2 weight % solution, utilize the membrane filter of 0.45 ��m to be filtered, and obtains measuring sample, and utilize the GPC of following condition to be measured, obtain the molecular weight of standard PMMA conversion.

Determinator: HLC-8220GPC (Dong Cao company system)

Chromatographic column: TSKgelMultiporeHXL-M (Dong Cao company system)

Eluent: oxolane (THF)

Elution speed: 0.3ml/ divides

Detector: RI (polarity (+))

Column temperature: 40 DEG C

According to these data, the area ratio in chromatograph calculate in all solids composition 100 mass % in paste compound, the quality % of the composition of molecular weight less than 3000. The lower limit that can utilize the molecular weight of the material that this algoscopy detects is 500.

In the paste compound of the present invention, when containing the cross-linking agent of molecular weight less than 3000 as cross-linking agent (D), the cross-linking agent (D) of such molecular weight ranges is not included in the quality of oligomer composition. When using such low-molecular-weight cross-linking agent (D), utilize and there is with paste compound the compositions of same composition except only mismatching cross-linking agent (D) carry out above-mentioned centrifugation, mensuration based on GPC, and carry out the quantitative of oligomer composition, the ratio of oligomer composition is obtained based on this value.

So, make the method that the oligomer component amount in paste compound reduces there is no particular determination, arbitrary method can be adopted. As the example of concrete grammar, the few material of use oligomer component amount can be enumerated as the material used when manufacturing paste compound. As the example of the method for the oligomer component amount reduced in each material, can enumerate: the preparation method utilizing oligomer generation amount few prepares the method for its material, the method for the method that carries out removing the operation of low-molecular-weight composition after preparing each material and the goods that utilize oligomer content ratio of a sufficiently low in commercially available goods. More specifically, it is possible to use the manufacture method of the paste compound of invention described below manufactures the paste compound of the present invention.

[2. the manufacture method of paste compound]

The method of the paste compound manufacturing the present invention is not particularly limited, it may be preferable to manufactured by method as described below. Hereinafter, the method is illustrated as the manufacture method of the present invention.

The manufacture method of the present invention includes: active substance (A), the water-soluble thickener (B) with carboxyl, the compositions (CX) comprising particle shape binding agent (C), cross-linking agent (D) and water carry out the operation mixed.

In this mixed processes, the order adding each composition is arbitrary, can suitably select to be suitable to the order of addition of mixing. Such as, can prepare in the aqueous medium of disperse medium by being dispersed in after above-mentioned each composition is optionally carried out partial pre-mix, can also by, after the adhesive composition that comprises water-soluble thickener (B), cross-linking agent (D) and particle shape binding agent (C) in preparation, making this adhesive composition and active substance (A) be scattered in and prepare as in the aqueous medium of disperse medium. Specifically, it is preferable that prepare paste compound by using the mixers such as ball mill, sand mill, ball mill, pigment dispersion machine, grater, ultrasonic dispersing machine, homogenizer, planetary-type mixer, FILMIX above-mentioned each composition and aqueous medium to be mixed.

In this mixed processes, relative to active substance (A) 100 mass parts, add the water-soluble thickener (B) of below more than 0.1 mass parts and 10 mass parts. It addition, relative to active substance (A) 100 mass parts, add the cross-linking agent (D) of below more than 0.01 mass parts and 5 mass parts. The interpolation of these compositions can suitably select to use in commercially available material and comprise these compositions and the enough few material of oligomer component amount (that is, oligomer component amount is less to for become the oligomer component amount in the paste compound manufacturing thing be the material of sufficient degree for below 0.10 mass % in all solids composition). As active substance (A), water-soluble thickener (B) and cross-linking agent (D), owing to such material easily can obtain as commercially available goods, therefore, by selecting such material, it is possible to be readily available the paste compound that oligomer component amount is few.

The addition of compositions (CX) makes, relative to active substance (A) 100 mass parts, to comprise particle shape binding agent (C) of below more than 0.1 mass parts and 5 mass parts. Compositions (CX) is following compositions: relative to all solids composition in compositions (CX), and the ratio utilizing the composition of molecular weight less than 3000 in the above-mentioned composition (CX) of gel permeation chromatography is below 0.01 mass %. For particle shape binding agent (C), its in the preparation, compared to other composition, the ratio of the oligomer composition of by-product is more prone to uprise. Therefore, as the material comprising particle shape binding agent (C), said composition is also used for the manufacture of paste compound by compositions (CX) that the amount of being mixed by preparing oligomer composition especially is few, it is possible to suppress the oligomer component amount in paste compound in desired relatively low amount.

Hereinafter, the method for the few compositions (CX) of the amount of being mixed obtaining such oligomer composition illustrates.

(i) in the manufacture of the aqueous dispersion of particle shape binding agent (C), by reduce water-soluble monomer make consumption, it is possible to reduce the amount of being mixed of oligomer composition in gained aqueous dispersion.

Such as, described above manufacture particle shape binding agent (C) particle aqueous dispersion manufacture method in, the use level of the unsaturated carboxylic acids such as the itaconic acid remained by reducing unreacted in water reactive low, easy, it is possible to the amount of being mixed of the oligomer composition in reduction gained aqueous dispersion. It addition, now, by combining the methacrylic acid monomer etc. using the hydroxyls such as a small amount of acrylic acid 2-hydroxy methacrylate, it is possible to the amount of being mixed of the oligomer composition in reduction aqueous dispersion.

(ii) in the manufacture of the aqueous dispersion of particle shape binding agent (C), by utilizing the operation that can improve monomer conversion to be polymerized, it is possible to the amount of being mixed of the oligomer composition in reduction gained aqueous dispersion.

Such as, making consumption, making polymerization temperature be the more such adjustment of low temperature of catalyst is reduced by carrying out, it is possible to reduce the amount of being mixed of oligomer composition.

(iii) by with said method (i) and/or (ii) in combination, aqueous dispersion that the manufacture of the aqueous dispersion by particle shape binding agent (C) is obtained carry out refining step further, it is possible to reduce the amount of being mixed of oligomer composition. For example, it is possible to be heated the operations such as decompression distillation. As described above, by such operation, unreacted monomer is easily removed, and on the other hand, oligomer is not readily removable, but by such refining step is used with said method (i) and/or (ii) combination, it is possible to reduce the amount of being mixed of the oligomer composition comprising monomer and oligomer.

[3. secondary battery cathode]

The lithium ion secondary battery cathode of the present invention possesses the negative pole obtained by the paste compound of the present invention and closes sheet material layers. The lithium ion secondary battery cathode of the present invention generally also comprises collector body. The lithium ion secondary battery cathode of the present invention closes sheet material layers by possessing the negative pole obtained by the paste compound of the present invention, when using in the battery, the effect such as the raising of cycle characteristics and the reduction of impedance can be realized, furthermore it is possible to realize the minimizing of dry linting when being processed into the shape can being accommodated in the outer package of battery.

The secondary battery cathode of the present invention can manufacture via following operation: such as, the paste compound of the present invention is coated the operation (painting process) on collector body, the paste compound coating on collector body is dried and formed on the current collector negative pole close sheet material layers operation (drying process) and optionally anticathode close the operation (heating process) that is heated further of sheet material layers.

When utilizing this manufacture method to manufacture, for instance, the heat that applies during by drying process, the heat applied in heating process, can make to be undertaken by the cross-linking reaction of cross-linking agent (D). Namely, negative pole close in sheet material layers can be formed water-soluble thickener (B) to each other, between water-soluble thickener (B) and particle shape binding agent (C) and/or particle shape binding agent (C) there occurs the cross-linked structure of crosslinking to each other via cross-linking agent (D), by this cross-linked structure, the expansion with discharge and recharge can be suppressed, simultaneously, the adaptation that collector body and negative pole close sheet material layers can be made to improve, and then make speed characteristic and cycle characteristics raising etc. make the electrical characteristic of secondary cell improve.

[3.1. painting process]

As the method coated by paste compound on collector body, it does not have particular determination, known method can be adopted. Specifically, as coating process, scraper plate method, infusion process, inverse roller method, direct roller method, intagliotype, extrusion molding, spread coating etc. can be adopted. At this point it is possible to paste compound only to be coated the one side of collector body, it is also possible to coat two sides. The thickness of the slurry film on collector body before drying after coating, it is possible to close the thickness of sheet material layers according to the dry negative pole obtained and suitably set.

Here, as the collector body of paste compound to be coated, can use and there is electric conductivity and there is the material of electrochemistry durability. Specifically, as collector body, the collector body being such as made up can be used of ferrum, copper, aluminum, nickel, rustless steel, titanium, tantalum, gold, platinum etc. Wherein, as the collector body for negative pole, it is particularly preferred that Copper Foil. Above-mentioned material can be used alone a kind, it is also possible to uses two or more with arbitrary ratio combine.

[3.2. drying process]

As the method that the paste compound on collector body is dried, be not particularly limited, known method can be adopted, for instance can enumerate utilize warm braw, hot blast, low wet wind dry, vacuum drying, utilize the seasoning of the irradiation of infrared ray, electron beam etc. By the paste compound on dry collector body in this wise, it is possible to form negative pole on the current collector and close sheet material layers, thus obtaining the secondary battery cathode possessing collector body and negative pole conjunction sheet material layers. When dry paste compound, pass through the heat applied, can make to be undertaken by the cross-linking reaction of cross-linking agent (D).

After drying process, the anticathode such as moulding press or roll squeezer can also be used to close sheet material layers and to implement pressurized treatments. Pass through pressurized treatments, it is possible to improve negative pole and close the adaptation between sheet material layers and collector body.

Additionally, it is preferred that after forming negative pole and closing sheet material layers, implement heating process so that cross-linking reaction carries out, so that cross-linked structure is more abundant. This heating process is carried out below more than 1 hour and less than 20 hours degree preferably in more than 80 DEG C and 160 DEG C.

[4. secondary cell]

The lithium rechargeable battery of the present invention possesses positive pole, negative pole, electrolyte and dividing plate, and possesses the secondary battery cathode of the present invention as negative pole. The secondary cell of the present invention is owing to employing the secondary battery cathode of the present invention, therefore, it is possible to while making the electrical characteristic such as speed characteristic and cycle characteristics improve, it is ensured that negative pole closes the adaptation between sheet material layers and collector body. The secondary cell of the present invention can be suitable for the mobile phones such as such as smart phone, panel computer, PC, electric automobile, fixing emergency battery etc.

[4.1. positive pole]

As the positive pole of secondary cell, the known positive pole being used as lithium ion secondary battery anode can be used. Specifically, as positive pole, the positive pole such as forming positive pole conjunction sheet material layers on the current collector can be used.

As collector body, the collector body being made up of metal materials such as aluminum can be used. Additionally, sheet material layers is closed as positive pole, the layer comprising known positive active material, conductive material and binding agent can be used, composition as binding agent, it is possible to use above-mentioned water-soluble thickener (B), particle shape binding agent (C) and the cross-linking agent (D) etc. being illustrated.

[4.2. electrolyte]

As electrolyte, it is usable in solvent dissolving the electrolyte of electrolyte.

Here, as solvent, it is possible to use electrolytical organic solvent can be dissolved. Specifically, as solvent, the solvent that can be used in the alkyl carbonate esters solvents such as ethylene carbonate, propylene carbonate, gamma-butyrolacton adding the viscosity modulating solvent such as 2,5-dimethyl-tetrahydrofurans, oxolane, diethyl carbonate, Ethyl methyl carbonate, dimethyl carbonate, methyl acetate, dimethoxy-ethane, dioxolane, methyl propionate, methyl formate and obtain.

As electrolyte, it is possible to use lithium salts. As lithium salts, for instance can be used in Japanese Unexamined Patent Publication 2012-204303 publication record lithium salts. In these lithium salts, from the view point of be easily dissolved in organic solvent and show high degree of dissociation, as electrolyte, it is preferable that LiPF₆��LiClO₄��CF₃SO₃Li��

It addition, electrolyte can be the gel electrolyte containing polymer and above-mentioned electrolyte, can also is that intrinsic (true property) polymer dielectric in addition.

[4.3. dividing plate]

As dividing plate, the dividing plate such as recorded in Japanese Unexamined Patent Publication 2012-204303 publication can be used. Wherein, from the view point of the thickness that dividing plate can be made overall is thinning, the ratio of the electrode active material that thus can improve in secondary cell is thus improving the capacity of per unit volume, it is preferable that the micro-porous film formed by the resin (polyethylene, polypropylene, polybutene, polrvinyl chloride) of TPO. It addition, as dividing plate, it is possible to use possess the dividing plate of the perforated membrane utilizing above-mentioned water-soluble thickener (B), particle shape binding agent (C) and the cross-linking agent (D) etc. being illustrated non-conductive particles to be bondd.

[manufacture method of 4.4. secondary cell]

The secondary cell of the present invention such as can manufacture by the following method: overlaps positive pole and negative pole across dividing plate, and optionally it be crimped according to cell shapes, put into battery case after bending etc., injects electrolyte to battery case and seals. In order to prevent the pressure of the inside of lithium rechargeable battery from raising, cross the generation of discharge and recharge etc., it is also possible to the overcurrent such as electric fuse, PTC-element is set as desired and prevents element, expansion alloy, lead plate etc. The shape of secondary cell can be the arbitrary shape in such as Coin shape, coin shape, flap-type, cylinder type, square, platypelloid type etc.

Embodiment

Hereinafter, the present invention is specifically explained in conjunction with the embodiments, but the present invention is not limited to these embodiments. In the following description, " % " and " part " of expression amount unless otherwise specified, is then quality criteria. It addition, when without specified otherwise, the operation of following description carries out when normal temperature and pressure.

In embodiment and comparative example, oligomer component amount in the glass transition temperature of particle shape binding agent (C) and the mensuration of gel content, paste compound measures, oligomer component amount mensuration in compositions (CX), the mensuration of tap density of active substance (A), the peel strength of negative pole and the speed characteristic of absorptive mensuration and lithium rechargeable battery and cycle characteristics mensuration, carry out as follows respectively.

Make the aqueous dispersions comprising particle shape binding agent (C) in 50% humidity, the environment of 23��26 DEG C dry 3 days, obtain the film of thickness 1 �� 0.3mm. This film is made to dry 10 hours in 60 DEG C of vacuum driers. Then, using dried film as sample, based on JISK7121, measure temperature-100 DEG C��180 DEG C, programming rate 5 DEG C/minute when, use DSC6220SII (differential scanning calorimetric analysis instrument, Nanotechnology company system) determine glass transition temperature (DEG C).

Prepare to comprise the aqueous dispersions of particle shape binding agent (C). Making this aqueous dispersions dry in 50% humidity, the environment of 23��25 DEG C, film forming is the film of thickness 1 �� 0.3mm. Make this film dry 10h in 60 DEG C of vacuum driers. This film is cut into the rectangle that length is 3��5mm on one side, and accurate weighing is about 1g.

The quality cutting the diaphragm obtained is set to w0. By this diaphragm in the oxolane (THF) of 50g, in the environment of 25 DEG C �� 1 DEG C, impregnated of 24 hours. Then, after the diaphragm pulled out from THF is carried out 3 hours vacuum dryings in 105 DEG C, the quality w1 of insoluble component is determined.

And then, calculate gel content (quality %) according to the following formula.

Gel content (quality %)=(w1/w0) �� 100

Weigh paste compound and be about 5g, in 60 DEG C dry 20 minutes, in 110 DEG C dry 20 minutes, in 60 DEG C of vacuum driers dry 10 hours further, determine dried quality, and obtained solid component concentration (W0) by its difference.

Paste compound is being about while 5g utilizes centrifugal separator (Kokusan company system, trade name: cooling high speed centrifuge (H-2000B)) to be cooled to 5 �� 1 DEG C, carry out centrifugation in 10 minutes operation at ambient pressure, with 7000rpm, gather its supernatant. Then, make supernatant after 60 DEG C of vacuum dryings 10 hours, implement the separation of the molecular weight determination based on preparative gel permeation chromatography (GPC) method and each composition, respectively acquirement and quality determination.

Specifically, molecular weight is obtained as follows: after being dissolved in oxolane and make 0.2 weight % solution, utilize the membrane filter of 0.45 ��m to be filtered, and obtains measuring sample, the GPC utilizing following condition is measured, and obtains the molecular weight of standard PMMA conversion.

Determinator: HLC-8220GPC (Dong Cao company system)

Chromatographic column: TSKgelMultiporeHXL-M (Dong Cao company system)

Eluent: oxolane (THF)

Elution speed: 0.3ml/ divides

Detector: RI (polarity (+))

Column temperature: 40 DEG C

According to these data, the area ratio in chromatograph calculating in all solids composition 100 mass % in paste compound, molecular weight is the quality % of the composition of less than 3000.

Except replacing paste compound to employ compositions (CX), it is measured in the same manner as above-mentioned<the oligomer component amount in paste compound measures>, having calculated in all solids composition 100 mass % in compositions (CX), molecular weight is the quality % of the composition of less than 3000.

Based on JISZ2512:2006, HosokawaMicron system, trade name " PowderTesterPT-S " is utilized to measure.

The secondary battery cathode made is dried 10 hours in 120 DEG C of vacuum driers, then cut long 100mm, wide 10mm rectangle as test film, make to have negative pole and close face-down cellophane tape (in JISZ1522 the material of regulation) being fitted in negative pole and closing sheet material layers surface of sheet material layers, one end of collector body is divided with draw rate 50mm/ towards vertical direction and carries out tractive and peel off, determine stress (cellophane tape is fixed in testing stand) now. Mensuration carries out 3 times, obtains its meansigma methods, and using this value as peel strength, has evaluated according to following standard. The value of peel strength is more big, then it represents that the adaptation that negative pole closes between sheet material layers and collector body is more excellent.

A: peel strength is more than 20N/m

B: peel strength is that 15N/m is less than 20N/m

C: peel strength is that 10N/m is less than 15N/m

D: peel strength is lower than 10N/m

The secondary battery cathode made is dried 10 hours in 120 DEG C of vacuum driers, then the circle of diameter 16mm is cut, determine thickness, and from this thickness, deduct the thickness of collector body, calculate the electrode before water retting and close the thickness (T1) of sheet material layers. The test film of this circle is added in sample bottle, inject ion exchange water 50mL, placed 12 hours in 60 DEG C. Then, take out the test film of this circle, after utilizing the ion exchange water of 50mL to wash, dry 1 hour in 120 DEG C, mensuration thickness, and from this thickness, deduct the thickness of collector body, calculate the electrode after water retting and close the thickness (T2) of sheet material layers. Utilize the thickness change that the definition of (T2-T1)/T1} �� 100% is caused by above-mentioned dipping in ion exchange water and heat treated, and evaluated according to following standard. This thickness change is more little, then it represents that water absorption is more low, and the expansion of electrode is more inhibited.

A: thickness change is lower than 8%

B: thickness change is 8% less than 10%

C: thickness change is 10% less than 12%

D: thickness change is more than 12%

By the lithium rechargeable battery of the laminated units type made after sealing through injecting electrolytic solution and vacuum, stand 5 hours in 25 DEG C, then utilize the constant flow method of 0.2C to charge to cell voltage at 25 DEG C and reach 3.65V, then carry out 12 hours aging process in 60 DEG C, utilize the constant flow method of 0.2C to carry out being discharged to cell voltage at 25 DEG C and reach 3.00V.

Then, it is charged with 4.2V, 0.2C speed at 25 DEG C, carries out discharging and then being charged with 0.2C, discharge with 2.0C with 0.2C. Now, discharge capacity when discharging with discharge rate 0.2C is defined as C_0.2, discharge capacity when discharging with discharge rate 2.0C is defined as C_2.0, obtain with �� C=C_2.0/C_0.2Time the Capacitance Shift Rate represented by discharge capacity �� 100 (%), and evaluated according to following standard. The value of this Capacitance Shift Rate �� C is more high, then it represents that discharging-rate performance (speed characteristic) is more excellent.

A: �� C is more than 83%

B: �� C is 82% less than 83%

C: �� C is 80% less than 82%

D: �� C is lower than 80%

The battery of use in the mensuration of speed characteristic, after carrying out the mensuration of speed characteristic, is utilized the constant flow method of 0.1C to be discharged to cell voltage in the environment of 25 DEG C and reaches 2.75V. Then, the operation of 100 cycle charge-discharges has been carried out under 45 DEG C of environment with the charge-discharge velocity of 4.2V, 0.5C. Now, measure the capacity of the 1st circulation and the discharge capacity X2 of initial stage discharge capacity X1 and the 100th circulation, obtain with �� C '=(X2/X1) �� 100 (%) Capacitance Shift Rate represented, and evaluated according to following standard. The value of this Capacitance Shift Rate �� C is more high, then it represents that cycle characteristics is more excellent.

A: �� C ' is more than 85%

B: �� C ' is 83% less than 85%

C: �� C ' is 80% less than 83%

D: �� C ' is lower than 80%

[manufacturing example 1: the preparation of particle shape binding agent (C1) used in embodiment 1��9, embodiment 13��17 and comparative example 1��2]

The 5MPa pressure vessel of belt stirrer adds the styrene 65 parts as aromatic vinyl monomer, as the 1 of aliphatic conjugated diene monomer, 3-butadiene 35 parts, 1 part of the itaconic acid as ethylenically unsaturated carboxylic acids monomer, the acrylic acid 2-hydroxy methacrylate 0.7 part as hydroxyl monomer, the uncle 12 carbon alkyl hydrosulfide 0.3 part as molecular weight regulator, the 12 carbon sodium alkyl benzene sulfonate 5 parts as emulsifying agent, the ion exchange water 150 parts as solvent and the potassium peroxydisulfate 1 part as polymerization initiator, after being sufficiently stirred for, heat to 55 DEG C to cause polymerization.

Reach moment of 95.0% in monomer consumption to carry out cooling down and terminate reaction. 5% sodium hydrate aqueous solution is added, by pH regulator to 8 in the aqueous dispersion comprising polymer thus obtained. Then, the removing of unreacted monomer has been carried out by heating decompression distillation. It is then cooled to less than 30 DEG C, obtain the aqueous dispersions (CX1) of particle shape binding agent (C1). Use the aqueous dispersions (CX1) of gained particle shape binding agent (C1), determined gel content and glass transition temperature by said method. The result measured, gel content is 92%, glass transition temperature (Tg) is 10 DEG C. It addition, in all solids composition 100 mass % in aqueous dispersions (CX1), the ratio of the composition of molecular weight less than 3000 is 0.01 mass %.

[manufacturing example 2: the preparation of particle shape binding agent (C2) used in embodiment 10]

Except making the ratio in the itaconic acid as ethylenically unsaturated carboxylic acids monomer be 2 parts, obtain the aqueous dispersions (CX2) of particle shape binding agent (C2) in the same manner as manufacturing example 1. Gel content is 92%, glass transition temperature (Tg) is 10 DEG C. It addition, in all solids composition 100 mass % in aqueous dispersions (CX2), the ratio of the composition of molecular weight less than 3000 is 0.02 mass %.

[manufacturing example 3: the preparation of particle shape binding agent (C3) used in embodiment 11]

Except to make the ratio in the itaconic acid as ethylenically unsaturated carboxylic acids monomer be 2.5 parts, make the ratio of the acrylic acid 2-hydroxy methacrylate as hydroxyl monomer be 1.5 parts except, obtain the aqueous dispersions (CX3) of particle shape binding agent (C3) in the same manner as manufacturing example 1. Gel content is 92%, glass transition temperature (Tg) is 10 DEG C. It addition, in all solids composition 100 mass % in aqueous dispersions (CX3), the ratio of the composition of molecular weight less than 3000 is 0.05 mass %.

[manufacturing example 4: the preparation of particle shape binding agent (C4) used in embodiment 12]

Except to make the ratio in the itaconic acid as ethylenically unsaturated carboxylic acids monomer be 3.0 parts, make the ratio of the acrylic acid 2-hydroxy methacrylate as hydroxyl monomer be 2.0 parts except, obtain the aqueous dispersions (CX4) of particle shape binding agent (C4) in the same manner as manufacturing example 1. Gel content is 92%, glass transition temperature (Tg) is 10 DEG C. It addition, in all solids composition 100 mass % in aqueous dispersions (CX4), the ratio of the composition of molecular weight less than 3000 is 0.08 mass %.

[manufacturing example 5: the preparation of particle shape binding agent (C5) used in comparative example 3]

Except to make the ratio in the itaconic acid as ethylenically unsaturated carboxylic acids monomer be 4.0 parts, make the ratio of the acrylic acid 2-hydroxy methacrylate as hydroxyl monomer be 2.5 parts except, obtain the aqueous dispersions (CX5) of particle shape binding agent (C5) in the same manner as manufacturing example 1. Gel content is 92%, glass transition temperature (Tg) is 10 DEG C. It addition, in all solids composition 100 mass % in aqueous dispersions (CX5), the ratio of the composition of molecular weight less than 3000 is 0.12 mass %.

[embodiment 1]

(preparation of 1-1. secondary cell paste compound)

Planetary-type mixer adds native graphite (capacity 360mAh/g, tap density 0.94, the BET specific surface area 3.0m as carbons active substance²/ g) 100 parts, as 1% aqueous solution of carboxymethyl cellulose viscosity 3500mPa s of degree of etherification falling 0.7,1% aqueous solution (goods name " MAC350HC ", Nippon Paper (strain) system) of water-soluble thickener with the suitable gauge of solid constituent 0.60 part, utilize planetary-type mixer with mixing 60 minutes of 40rpm, obtain pastel. In the pastel obtained, add 1% aqueous solution (identical with above-mentioned use) of mixing water soluble surfactant further, make it reach 0.40 part (namely with the suitable gauge of solid constituent, the summation of the addition of the addition of the 1st time and the 2nd time is 1.00 parts), mix 30 minutes with 40rpm. Then, put into the aqueous dispersions (CX1) manufacturing particle shape binding agent (C1) obtained in example 1 with the suitable gauge of solid constituent 1.50 parts, carbodiimide class cross-linking agent (trade name " SV-02 ", NisshinboChemical (strain) make) with the suitable gauge of solid constituent 0.075 part, further, add ion exchange water and carry out mixing, making solid component concentration reach 50%. Thus, paste compound used by the secondary cell (negative pole) being prepared for comprising active substance (A), water-soluble thickener (B), particle shape binding agent (C), cross-linking agent (D) and water.

Gained paste compound measures the quality % of the composition of all solids composition 100 mass % middle-molecular-weihydroxyethyl less than 3000 in paste compound, and result is 0.01 mass %.

(manufacture of 1-2. negative pole)

The Copper Foil (collector body) that the secondary cell paste compound obtained in operation (1-1) is coated on thickness 20 ��m by unfilled corner wheel coating machine is utilized above and to make coating amount reach 8.9��9.2mg/cm². The Copper Foil being coated with this secondary cell paste compound transmits 2 minutes in the baking oven of 60 DEG C with the speed of 0.3m/ minute, then transmits 2 minutes in the baking oven of 110 DEG C, thus makes the paste compound on Copper Foil dry, obtains the former film of negative pole.

The compacting of former for the negative pole obtained film roll squeezer is reached 1.45g/cm to closing sheet material layers density³��1.55g/cm³, then, in order to remove moisture and promote further crosslinking and under vacuum, the environment of 120 DEG C is placed 10 hours. Thus, the negative pole of the negative pole conjunction sheet material layers comprising collector body and formation on this collector body is obtained.

Gained negative pole be have rated peel strength and water absorption. Result is as shown in table 1.

(manufacture of 1-3. positive pole)

Planetary-type mixer adds the LiCoO as positive active material₂100 parts, 2-methyl pyrrolidone as the acetylene black 2 parts (electrochemically industry (strain) system " HS-100 ") of conductive auxiliary agent, PVDF (Kynoar, (strain) KurehaChemical system " KF-1100 ") 2 parts and the amount that makes total solid constituent concentration be 67%, and mix, it is prepared for positive pole paste compound.

Unfilled corner wheel coating machine is utilized to be coated on the aluminium foil of thickness 20 ��m by the positive electrode obtained and reach 19.5��20.5mg/cm². The aluminium foil being coated with this paste compound transmits 2 minutes in the baking oven of 60 DEG C with the 0.5m/ speed divided, and then carries out 2 minutes heat treated in 120 DEG C, obtains the former film of positive pole.

The density that former for the positive pole obtained film roll squeezer carries out after suppressing and make compacting is reached 3.40��3.50g/cm³, then, under vacuum, the environment of 120 DEG C is placed 3 hours in order to remove moisture, obtain to comprise collector body and form the positive pole on this collector body and close the positive pole of sheet material layers.

(manufacture of 1-4. lithium rechargeable battery)

Polypropylene dividing plate (wide 65mm, long 500mm, the thickness 25 ��m of monolayer are prepared; Utilize dry process manufacture; The porosity 55%), and it is cut into 5 �� 5cm²Rectangle, obtain the dividing plate of rectangle.

The negative pole made in operation (1-2) is cut into the rectangle of 4.0 �� 3.0cm, obtains the negative pole of rectangle.

The positive pole made in operation (1-3) is cut into the rectangle of 3.8 �� 2.8cm, obtains the positive pole of rectangle.

Mixed solvent 100 parts by volume of ethylene carbonate (EC)/Ethyl methyl carbonate (EMC)=3/7 (volume ratio) adds vinylene carbonate 2 parts by volume as additive and adds LiPF₆Make its concentration reach 1.0M, mix, obtain electrolyte.

Additionally, as the outer package of battery, prepared aluminum housing material.

The positive pole of rectangle is arranged in aluminum housing material, the surface on the current collection side of positive pole is connected with aluminum housing material. Then, the dividing plate configuring rectangle on the surface of sheet material layers side is closed at the positive pole of the positive pole of rectangle. Further, the negative pole of rectangle is arranged on dividing plate, the surface that the negative pole of negative pole closes sheet material layers side is connected with dividing plate. Then, filling electrolyte in aluminum housing material. Further, carry out the heat-sealing of 150 DEG C and aluminum housing material is sealed, manufactured the lithium rechargeable battery of laminated units type.

For the lithium rechargeable battery made, determine speed characteristic and cycle characteristics and evaluated. Result is as shown in table 1.

[embodiment 2��3]

In the preparation of the secondary cell paste compound of operation (1-1), the addition of carbodiimide class cross-linking agent is changed to the suitable gauge of solid constituent 0.03 part (embodiment 2) or 0.15 part (embodiment 3), in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[embodiment 4��6]

In the preparation of the secondary cell paste compound of operation (1-1), by the quantitative change of particle shape binding agent (C1) more with the suitable gauge of solid constituent 1 part (embodiment 4), 0.5 part (embodiment 5) or 2 parts (embodiment 6), and the addition of carbodiimide class cross-linking agent is changed to the suitable gauge of solid constituent 0.05 part (embodiment 4), 0.025 part (embodiment 5) or 0.1 part (embodiment 6), in addition, manufacture secondary battery negative pole paste compound similarly to Example 1, negative pole, positive pole, and lithium rechargeable battery, and evaluated. result is as shown in table 1.

[embodiment 7]

In the preparation of the secondary cell paste compound of operation (1-1), the native graphite as carbons active substance is changed to Delanium (capacity 360mAh/g, tap density 0.67, BET specific surface area 3.6m²/ g), in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[embodiment 8]

In the preparation of the secondary cell paste compound of operation (1-1), as carbons active substance, it is changed to the native graphite making to use in embodiment 1 and the Delanium used in embodiment 7 is 80/20 (mass ratio) (capacity 360mAh/g, tap density 0.73), and addition is changed to 100 mass parts, in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[embodiment 9]

In the preparation of the secondary cell paste compound of operation (1-1), as carbons active substance, it is changed to the native graphite making to use in embodiment 1 and the Delanium used in embodiment 7 is 60/40 (mass ratio) (capacity 360mAh/g, tap density 0.82) and addition is changed to 100 mass parts, in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[embodiment 10��12]

In the preparation of the secondary cell paste compound of operation (1-1), replace particle shape binding agent (C1) and employing manufacture in example 2 obtain particle shape binding agent (C2) (embodiment 10), manufacture particle shape binding agent (C3) (embodiment 11) obtained in example 3 or manufacture particle shape binding agent (C4) (embodiment 12) obtained in example 4, in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1. In all solids composition 100 mass % in paste compound, the quality % of the composition of molecular weight less than 3000 is 0.02 mass % (embodiment 10), 0.05 mass % (embodiment 11) and 0.08 mass % (embodiment 12).

[embodiment 13]

(preparation of 13-1. water-soluble thickener)

Utilize NaOH (medicine pure with light, guaranteed reagents) to adjust to pH=8 1% aqueous solution of polycarboxylic acids (Aldrich system, molecular weight=1,250,000), obtain the aqueous solution of the sodium salt (PAA-Na) of polycarboxylic acids.

By the aqueous solution of gained PAA-Na, carboxymethyl cellulose (goods name " MAC350HC ", Nippon Paper (strain) are made) and water mixing, obtain the aqueous solution of water-soluble thickener. Obtained aqueous solution contains carboxymethyl cellulose and PAA-Na with the ratio of 80:20, it addition, solid constituent ratio (in aqueous solution total amount the total ratio of carboxymethyl cellulose and PAA-Na) is 1.0%.

(manufactures of 13-2. lithium rechargeable battery etc.)

In the preparation of the secondary cell paste compound of operation (1-1), replace 1% aqueous solution of carboxymethyl cellulose and employ the aqueous solution of the water-soluble thickener obtained in operation (13-1) that (addition is calculated as 1.0 parts with solid constituent a great deal of; 1st time add in solid constituent be quite calculated as 0.6 part, the 2nd time add in solid constituent be quite calculated as 0.4 part), in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[embodiment 14]

(preparation of 14-1. water-soluble thickener)

Utilize NaOH (medicine pure with light, guaranteed reagents) to adjust to pH=8 1% aqueous solution of polycarboxylic acids (Aldrich system, molecular weight=1,250,000), obtain the aqueous solution of the lithium salts (PAA-Li) of polycarboxylic acids.

By the aqueous solution of gained PAA-Li, carboxymethyl cellulose (goods name " MAC350HC ", Nippon Paper (strain) are made) and water mixing, obtain the aqueous solution of water-soluble thickener. Obtained aqueous solution contains carboxymethyl cellulose and PAA-Li with the ratio of 80:20, it addition, solid constituent ratio (in aqueous solution total amount the total ratio of carboxymethyl cellulose and PAA-Li) is 1.0%.

(manufactures of 14-2. lithium rechargeable battery etc.)

In the preparation of the secondary cell paste compound of operation (1-1), replace 1% aqueous solution of carboxymethyl cellulose and employ the aqueous solution of the water-soluble thickener obtained in operation (14-1) that (addition is calculated as 1.0 parts with solid constituent a great deal of; Quite it is calculated as 0.6 part, the 2nd time with solid constituent in adding for 1st time in adding and is quite calculated as 0.4 part with solid constituent), in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[embodiment 15]

(preparation of 15-1. secondary cell paste compound)

Planetary-type mixer coordinates the native graphite (capacity 360mAh/g, tap density 0.94) 100 parts as carbons active substance, as water-soluble thickener carboxymethyl cellulose (goods name " MAC350HC ", Nippon Paper (strain) system, degree of etherification falling 0.7,1% aqueous solution viscosity 3500mPa s) 1% aqueous solution with the suitable gauge of solid constituent 0.60 part, utilize planetary-type mixer with mixing 60 minutes of 40rpm, obtain pastel. 1% aqueous solution (identical with above-mentioned use) of water-soluble thickener is added further with the suitable gauge of solid constituent 0.40 part (namely in the pastel obtained, the summation of the addition of the addition of the 1st time and the 2nd time is 1.00 parts) and cellulose nano-fibrous (goods name " CELISH (registered trade mark) KY-100G " fibre diameter 0.07 ��m, Daicel chemical industrial company system) convert 0.0075 part (when particle shaped polymer (C) is set to 100 parts with solid constituent, be equivalent to 0.5 part), mix 30 minutes with 40rpm. Then, put into the aqueous dispersions (CX1) manufacturing particle shape binding agent (C1) obtained in example 1 with the suitable gauge of solid constituent 1.50 parts, carbodiimide class cross-linking agent (trade name " SV-02 ", NisshinboChemical (strain) make) with the suitable gauge of solid constituent 0.075 part, further, add ion exchange water and carry out mixing, making solid component concentration reach 50%. Thus, paste compound used by the secondary cell (negative pole) being prepared for comprising active substance (A), water-soluble thickener (B), particle shape binding agent (C), cross-linking agent (D) and water.

(manufactures of 15-2. lithium rechargeable battery etc.)

In the manufacture of the negative pole of operation (1-2), replace the secondary cell paste compound that the secondary cell paste compound that obtains in operation (1-1) and employing obtains in operation (15-1), in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery in the same manner as operation (1-2)��(1-4) of embodiment 1, and evaluated. Result is as shown in table 1.

[embodiment 16]

Make cellulose nano-fibrous addition relative to particle shaped polymer (C) 100 parts for solid component meter 0.8 part, in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 15, and evaluated. Result is as shown in table 1.

[embodiment 17]

In the preparation of the secondary cell paste compound of operation (1-1), carbodiimide class cross-linking agent is replaced to employOxazolines cross-linking agent (trade name " EPOCROSWS-700 ", Japan's catalyst (strain) system), in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[comparative example 1]

In the preparation of the secondary cell paste compound of operation (1-1), it is not added with cross-linking agent, in addition, manufactured secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[comparative example 2]

In the preparation of the secondary cell paste compound of operation (1-1), the addition of carbodiimide class cross-linking agent is changed to the suitable gauge of solid constituent 6 parts, in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1.

[comparative example 3]

In the preparation of the secondary cell paste compound of operation (1-1), particle shape binding agent (C1) is replaced to employ and manufacturing in example 5 particle shape binding agent (C5) obtained, in addition, manufacture secondary battery negative pole paste compound, negative pole, positive pole and lithium rechargeable battery similarly to Example 1, and evaluated. Result is as shown in table 1. In all solids composition 100 mass % in paste compound, the quality % of the composition of molecular weight less than 3000 is 0.12 mass %.

[table 1]

As shown in the result of table 1, being the negative pole manufactured in specified quantitative below example 1��17 in the ratio employing given active substance (A), water-soluble thickener (B), particle shape binding agent (C) and cross-linking agent and oligomer composition with specific ratio, it can be secondary cell imparting high-peeling strength, low water absorbable, high-rate characteristics and the such good characteristic of high cycle characteristics that balance possesses well.

Claims

1. a lithium ion secondary battery negative pole paste compound, it comprises:

Active substance (A) 100 mass parts,

More than cross-linking agent (D) 0.01 mass parts and below 5 mass parts and

Water,

Wherein, relative to all solids composition of described paste compound, the ratio utilizing the composition of the molecular weight less than 3000 in the described paste compound of gel permeation chromatography is below 0.10 mass %.

2. paste compound according to claim 1, wherein, the tap density of described active substance (A) is more than 0.70.

3. paste compound according to claim 1 and 2, wherein, described cross-linking agent (D) has carbodiimide structure.

4. the paste compound according to any one of claims 1 to 3, wherein, described particle shape binding agent (C) has the functional group reacted with described cross-linking agent (D), and described functional group is the group in carboxyl, hydroxyl, glycidyl ether, thiol and their combination.

5. a lithium ion secondary battery cathode, it has the negative pole conjunction sheet material layers that the paste compound according to any one of Claims 1 to 4 obtains.

6. a lithium rechargeable battery, it possesses:

Lithium ion secondary battery cathode described in claim 5,

Positive pole,

Electrolyte and

Dividing plate.

7. a manufacture method for paste compound, it is the method for the paste compound according to any one of manufacturing claims 1��4, wherein, the method include by

Active substance (A) 100 mass parts,

Comprise below more than particle shape binding agent (C) 0.1 mass parts and 5 mass parts compositions (CX),

More than cross-linking agent (D) 0.01 mass parts and below 5 mass parts and

Water

Carry out the operation mixed,

Relative to all solids composition in described compositions (CX), the ratio utilizing the composition of molecular weight less than 3000 in the described compositions (CX) of gel permeation chromatography is below 0.01 mass %.