JP2016122611A - Composition for nonaqueous secondary battery functional layer, nonaqueous secondary battery functional layer, and nonaqueous secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for a nonaqueous secondary battery functional layer, which enables the formation of a functional layer for a nonaqueous secondary battery; the functional layer can show superior adhesiveness and impart superior battery characteristics to a secondary battery even after immersed in electrolytic solution.SOLUTION: A composition for a nonaqueous secondary battery functional layer comprises: particulate polymer; and an amino acid. The rate of the amino acid to 100 pts.mass of the particulate polymer is 0.1-5 pts.mass. The particulate polymer has a core-shell structure including a core part and a shell part partially covering the outer surface of the core part. The core part includes a polymer of which the degree of swelling by electrolyte is 5 to 30 times. The shell part includes a polymer of which the degree of swelling by the electrolyte is over 1 to 4 times.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-aqueous secondary battery functional layer composition, a non-aqueous secondary battery functional layer, and a non-aqueous secondary battery.

  Non-aqueous secondary batteries such as lithium ion secondary batteries (hereinafter sometimes simply referred to as “secondary batteries”) have the characteristics that they are small and light, have high energy density, and can be repeatedly charged and discharged. Is used in a wide range of applications. The non-aqueous secondary battery generally includes a battery member such as a positive electrode, a negative electrode, and a separator that separates the positive electrode and the negative electrode and prevents a short circuit between the positive electrode and the negative electrode.

  Here, in recent years, in secondary batteries, a porous film layer for improving heat resistance and strength, an adhesive layer for bonding battery members, and the like (hereinafter, these are collectively referred to as “functional layer”). In some cases, battery members are used. Specifically, an electrode in which a functional layer is further formed on an electrode base material in which an electrode mixture layer is provided on a current collector, or a separator in which a functional layer is formed on a separator base material is a battery member. It is used as

  And the improvement of a functional layer is performed actively for the purpose of the further performance enhancement of the secondary battery using the battery member which has those functional layers (for example, refer patent document 1, 2).

  Specifically, in Patent Document 1, as a separator for a secondary battery, a porous membrane layer containing non-conductive particles and a binder is formed on a separator substrate, and the porous membrane layer is formed on the porous membrane layer. In addition, a separator has been proposed in which an adhesive layer containing a predetermined particulate polymer is further provided. And in patent document 1, by using the separator provided with the said contact bonding layer, it is reported that a separator and an electrode can be adhere | attached favorably through an contact bonding layer, and the battery characteristic of a secondary battery can be improved. Yes.

  Patent Document 2 proposes forming a porous film layer on the surface of a separator substrate or electrode substrate for a secondary battery using a slurry containing amino acids, ceramic particles, a binder and a solvent. Yes. And in patent document 2, since the said slurry contains an amino acid, the reduction | decrease of the porosity (increase of internal resistance) of the porous membrane layer by aggregation of a ceramic particle is prevented, and the battery characteristic of a secondary battery is improved. It has been reported that can be made.

International Publication No. 2013/151144 JP 2014-066762 A

  However, the adhesive layer using the particulate polymer described in Patent Document 1 and the porous film layer using the slurry described in Patent Document 2 have a tendency to deteriorate in adhesion when immersed in an electrolytic solution. Therefore, the non-aqueous secondary battery including these functional layers may not have sufficiently good battery characteristics such as high-temperature cycle characteristics. Therefore, the conventional functional layer has a room for improvement in that it exhibits high adhesiveness even after being immersed in an electrolytic solution and further improves the battery characteristics of the nonaqueous secondary battery including the functional layer. there were.

Therefore, the present invention provides a non-aqueous secondary battery capable of forming a functional layer for a non-aqueous secondary battery that can exhibit excellent adhesive properties even after being immersed in an electrolytic solution and can provide excellent battery characteristics to the secondary battery. It aims at providing the composition for secondary battery functional layers.
Another object of the present invention is to provide a functional layer for a non-aqueous secondary battery that exhibits excellent adhesion even after being immersed in an electrolytic solution and can provide excellent battery characteristics to a secondary battery. To do.
Furthermore, an object of this invention is to provide the non-aqueous secondary battery which is excellent in battery characteristics, such as a high temperature cycling characteristic.

  The present inventor has intensively studied for the purpose of solving the above problems. The inventor exhibits excellent adhesion even after being immersed in an electrolytic solution by using a composition containing a particulate polymer having a predetermined core-shell structure and properties and an amino acid in a specific ratio. The present inventors have found that a functional layer that can provide excellent battery characteristics to a secondary battery can be obtained, and the present invention has been completed.

That is, the present invention aims to advantageously solve the above problems, and the composition for a non-aqueous secondary battery functional layer of the present invention comprises a non-aqueous two-component composition containing a particulate polymer and an amino acid. The composition for a secondary battery functional layer, wherein the ratio of the amino acid is 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the particulate polymer, and the particulate polymer includes: a core part; And a shell part partly covering the outer surface of the core part, the core part is made of a polymer having an electrolyte swelling degree of 5 times or more and 30 times or less, and the shell part is It is characterized by comprising a polymer having an electrolyte solution swelling degree of more than 1 time and 4 times or less. Thus, if a composition containing a particulate polymer having the predetermined core-shell structure and properties described above and an amino acid in a specific ratio is used for forming a functional layer, excellent adhesion even after being immersed in an electrolyte solution It is possible to provide a functional layer that can exhibit excellent battery performance and can provide excellent battery characteristics to the secondary battery.
In the present invention, the “electrolyte swelling degree” of the polymer constituting the core part and the shell part of the particulate polymer can be measured using the measuring method described in the examples of the present specification.

The composition for a non-aqueous secondary battery functional layer of the present invention has a glass transition temperature of −50 ° C. or more and 150 ° C. or less of the polymer constituting the core portion, and the polymer glass constituting the shell portion. The transition temperature is preferably 50 ° C. or higher and 200 ° C. or lower. Thus, the adhesiveness of the functional layer obtained by using the composition and the functional layer obtained by setting the glass transition temperature of the polymer constituting the core part and the shell part within the above-mentioned ranges, respectively. The battery characteristics of the secondary battery can be further improved.
In the present invention, the “glass transition temperature” of the polymer constituting the core part and the shell part of the particulate polymer can be measured using the measuring method described in the examples of the present specification.

  Furthermore, in the composition for a non-aqueous secondary battery functional layer of the present invention, the amino acid preferably contains aspartic acid and / or glutamic acid. Thus, by using aspartic acid and / or glutamic acid as amino acids, the adhesion of the functional layer formed using the composition and the battery characteristics of the secondary battery including the functional layer are further improved. Can do.

  Moreover, this invention aims at solving the said subject advantageously, The functional layer for non-aqueous secondary batteries of this invention is the composition for any of the non-aqueous secondary battery functional layers mentioned above. It is characterized by being formed using. A functional layer formed using any of the above-described functional layer compositions as a material is excellent in adhesion in an electrolytic solution, and can exhibit excellent electrical characteristics in a secondary battery.

  Moreover, this invention aims at solving the said subject advantageously, The non-aqueous secondary battery of this invention is equipped with the functional layer for non-aqueous secondary batteries mentioned above, It is characterized by the above-mentioned. A secondary battery including the above-described functional layer for a non-aqueous secondary battery is excellent in electrical characteristics such as high-temperature cycle characteristics.

According to the present invention, a non-aqueous secondary battery capable of forming a functional layer for a non-aqueous secondary battery that exhibits excellent adhesion even after being immersed in an electrolytic solution and can provide excellent battery characteristics to the secondary battery. A composition for a secondary battery functional layer can be provided.
In addition, according to the present invention, it is possible to provide a functional layer for a non-aqueous secondary battery that exhibits excellent adhesion even after being immersed in an electrolytic solution and can provide excellent battery characteristics for a secondary battery. it can.
Furthermore, according to this invention, the non-aqueous secondary battery which is excellent in battery characteristics, such as a high temperature cycling characteristic, can be provided.

It is sectional drawing which shows typically the structure of an example of the particulate polymer contained in the composition for non-aqueous secondary battery functional layers of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the composition for non-aqueous secondary battery functional layers of the present invention is used as a material for preparing the functional layer for non-aqueous secondary batteries of the present invention. Moreover, the functional layer for non-aqueous secondary batteries of this invention is prepared using the composition for non-aqueous secondary battery functional layers of this invention, for example, comprises a part of separator and an electrode. The non-aqueous secondary battery functional layer of the present invention formed using the non-aqueous secondary battery functional layer composition of the present invention improves the heat resistance and strength of battery members such as separators and electrodes. It may be a porous film layer, an adhesive layer for bonding battery members together, or a layer that exhibits both functions of the porous film layer and the adhesive layer. And the non-aqueous secondary battery of this invention is equipped with the functional layer for non-aqueous secondary batteries of this invention at least.

(Composition for functional layer of non-aqueous secondary battery)
The composition for a functional layer for a non-aqueous secondary battery contains at least a particulate polymer having a predetermined structure and properties and an amino acid, and optionally includes a binder for a functional layer, non-conductive particles (particulate polymer). And a slurry composition containing other components and containing water or the like as a dispersion medium.
And since the functional layer formed using the composition for a non-aqueous secondary battery functional layer of the present invention contains a particulate polymer having a predetermined structure and properties and an amino acid at a specific ratio, Even after immersion in the electrolytic solution, excellent adhesiveness can be exhibited, and excellent battery characteristics can be exhibited in the non-aqueous secondary battery. Specifically, the functional layer formed using the composition for a non-aqueous secondary battery functional layer of the present invention contains a predetermined particulate polymer that exhibits excellent adhesiveness in the electrolytic solution. Therefore, even after immersion in the electrolytic solution, excellent adhesiveness can be exhibited, and excellent battery characteristics can be exhibited in the non-aqueous secondary battery. In addition, since the composition for a non-aqueous secondary battery functional layer of the present invention uses a particulate polymer and an amino acid together in a specific ratio, the particulate polymer is favorably improved in the composition and in the functional layer. It can be dispersed to further enhance the adhesion of the functional layer in the electrolytic solution, and the battery characteristics of the non-aqueous secondary battery can be improved.

<Particulate polymer>
The particulate polymer contained in the composition for a non-aqueous secondary battery functional layer has a function of exerting excellent adhesiveness in a functional layer formed using the composition for a non-aqueous secondary battery functional layer.
The particulate polymer has a core-shell structure including a core portion and a shell portion that partially covers the outer surface of the core portion, and the core portion has an electrolyte swelling degree of 5 times or more and 30. The shell part is made of a polymer having an electrolyte solution swelling degree of more than 1 time and 4 times or less.

  Here, the particulate polymer having the above structure and properties exhibits excellent adhesiveness in the electrolytic solution, and further, the elution of components into the electrolytic solution is small, and excellent adhesiveness can be maintained for a long time. it can. And the functional layer obtained using the composition for functional layers can improve the battery characteristic of a secondary battery favorably. In addition, since the functional layer obtained using the functional layer composition does not exhibit a large adhesive force before being immersed in the electrolytic solution, the functional layer itself and the member including the functional layer are blocked (functional layer). Or sticking between members via the functional layer), and handling properties are excellent.

The reason why the above-described excellent effect can be obtained by using the particulate polymer is not clear, but is presumed to be as follows.
That is, the polymer constituting the shell part of the particulate polymer swells to some extent with respect to the electrolytic solution. At this time, for example, the functional group of the polymer of the swollen shell part is activated, and the separator base or electrode base on which the functional layer is formed, or the electrode or separator adhered to the battery member having the functional layer, etc. The shell part can be firmly bonded to the battery member due to factors such as causing a chemical or electrical interaction with a functional group on the surface of the battery member. On the other hand, the shell portion does not exhibit a large adhesive force before it swells in the electrolytic solution. Therefore, in the functional layer containing the particulate polymer, it is inferred that it is possible to strongly bond battery members (for example, a separator and an electrode) in the electrolyte solution while suppressing the occurrence of blocking. Is done.
Moreover, the polymer of the shell part and the polymer of the core part both have an electrolyte solution swelling degree set to a predetermined value or less, and do not swell excessively with respect to the electrolyte solution. Therefore, for example, it is speculated that the excellent adhesiveness described above can be sufficiently exhibited even after the secondary battery is operated for a long time.
Furthermore, since the dispersibility of the particulate polymer is improved in the presence of an amino acid, the adhesiveness of the functional layer in the electrolytic solution can be further improved by using it together with a predetermined amount of amino acid. In addition, since the polymer in the shell portion swells moderately with respect to the electrolyte solution, the particulate polymer can capture the amino acid on the surface portion of the particulate polymer when used in combination with the amino acid. . Accordingly, it is possible to suppress elution of amino acids from the functional layer into the electrolytic solution in the non-aqueous secondary battery, and to prevent battery characteristics such as high-temperature cycle characteristics from being degraded due to decomposition of the eluted amino acids.
And when using the functional layer containing the said particulate polymer, since it can adhere | attach a battery member strongly in electrolyte solution as mentioned above, in a secondary battery provided with the said functional layer, a functional layer is used. It is difficult to generate a gap between the battery members bonded via each other (for example, between the separator and the electrode). Therefore, in the secondary battery using the functional layer containing the particulate polymer, the distance between the positive electrode and the negative electrode is not easily increased in the secondary battery, the internal resistance of the secondary battery can be reduced, and the electrochemical in the electrode can be reduced. The reaction field of the reaction is unlikely to be uneven. Furthermore, in the secondary battery, even if charging and discharging are repeated, it is difficult to form a gap between the separator and the electrode, and the battery capacity is unlikely to decrease. Thus, it is assumed that battery characteristics such as excellent high-temperature cycle characteristics can be realized.
Furthermore, the polymer constituting the core of the particulate polymer swells greatly with respect to the electrolytic solution. When the polymer is greatly swollen in the electrolytic solution, the gap between the molecules of the polymer becomes large, and ions easily pass between the molecules. Further, the polymer in the core part of the particulate polymer is not completely covered by the shell part. Therefore, since ions easily pass through the core portion in the electrolytic solution, the particulate polymer can exhibit high ion diffusibility. Therefore, if the particulate polymer is used, it is possible to suppress an increase in resistance due to the functional layer and to suppress a decrease in battery characteristics such as a low temperature output characteristic.
In addition, as above-mentioned, a particulate polymer exhibits the outstanding adhesiveness by swelling to electrolyte solution, and does not exhibit big adhesive force before being immersed in electrolyte solution. However, the particulate polymer does not exhibit any adhesiveness unless it swells in the electrolytic solution, and even if it is not swollen in the electrolytic solution, for example, at a certain temperature or higher (for example, 50 ° C. or higher). Adhesiveness can be expressed by heating.

[Structure of particulate polymer]
Here, the particulate polymer has a core-shell structure including a core part and a shell part covering the outer surface of the core part. The shell portion partially covers the outer surface of the core portion. That is, the shell part of the particulate polymer covers the outer surface of the core part, but does not cover the entire outer surface of the core part. Even if it appears that the outer surface of the core part is completely covered by the shell part, the shell part is outside the core part as long as a hole that communicates the inside and outside of the shell part is formed. A shell part that partially covers the surface. Therefore, for example, a particulate polymer having a shell portion having pores communicating from the outer surface of the shell portion (that is, the peripheral surface of the particulate polymer) to the outer surface of the core portion is included in the particulate polymer. It is.

  Specifically, as shown in FIG. 1, the cross-sectional structure of an example of the particulate polymer has a core-shell structure including a core part 110 and a shell part 120. Here, the core part 110 is a part located inside the shell part 120 in the particulate polymer 100. The shell portion 120 is a portion that covers the outer surface 110 </ b> S of the core portion 110, and is usually the outermost portion in the particulate polymer 100. The shell portion 120 does not cover the entire outer surface 110S of the core portion 110, but partially covers the outer surface 110S of the core portion 110.

[[Coverage]]
Here, in the particulate polymer, the average ratio (coverage) in which the outer surface of the core part is covered by the shell part is preferably 10% or more, more preferably 30% or more, and still more preferably 50% or more, Preferably it is 95% or less, More preferably, it is 90% or less, More preferably, it is 80% or less. By making the coverage more than the lower limit of the above range, the occurrence of blocking between the battery members is suppressed, the adhesion between the battery members in the electrolytic solution is enhanced, and the high-temperature cycle characteristics of the secondary battery are improved. be able to. In addition, by setting the coverage to be equal to or less than the upper limit of the above range, it is possible to improve the low temperature output characteristics of the secondary battery by expressing high ion diffusibility in the functional layer.
In addition, in this invention, "the average ratio (coverage) by which the outer surface of a core part is covered with a shell part" can be measured using the measuring method as described in the Example of this specification.

[[Volume average particle diameter D50]]
Further, the volume average particle diameter D50 of the particulate polymer is preferably 0.01 μm or more, more preferably 0.1 μm or more, further preferably 0.3 μm or more, preferably 10 μm or less, more preferably 5 μm or less, More preferably, it is 1 μm or less. By setting the volume average particle diameter D50 of the particulate polymer to be equal to or greater than the lower limit of the above range, it is possible to suppress the increase in internal resistance of the functional layer and improve the low temperature output characteristics of the secondary battery. Moreover, by making volume average particle diameter D50 of a particulate polymer below an upper limit, the adhesiveness of the battery members in electrolyte solution can be improved, and the high temperature cycling characteristic of a secondary battery can be improved.
In the present invention, the “volume average particle diameter D50” of the particulate polymer can be measured using the measuring method described in the examples of the present specification.

[[Core shell ratio]]
Further, the shell part preferably has an average thickness that falls within a predetermined range with respect to the volume average particle diameter D50 of the particulate polymer. Specifically, the average thickness (core-shell ratio) of the shell part with respect to the volume average particle diameter D50 of the particulate polymer is preferably 1% or more, more preferably 5% or more, further preferably 8% or more, preferably Is 30% or less, more preferably 25% or less, and still more preferably 20% or less. By setting the core-shell ratio to be equal to or higher than the lower limit of the above range, the adhesion of the functional layer in the electrolytic solution can be further improved and the high-temperature cycle characteristics of the secondary battery can be improved. Moreover, the low temperature output characteristic of a secondary battery can further be improved by making a core-shell ratio below the upper limit of the said range.
In the present invention, the “core-shell ratio” can be measured using the measurement method described in the examples of the present specification.

  In addition, the particulate polymer may be provided with arbitrary components other than the core part and shell part which were mentioned above, unless the expected effect is impaired remarkably. Specifically, for example, the particulate polymer may have a part formed of a polymer different from the core part inside the core part. As a specific example, the seed particles used when the particulate polymer is produced by the seed polymerization method may remain inside the core portion. However, it is preferable that the particulate polymer includes only the core part and the shell part from the viewpoint of remarkably exhibiting the intended effect.

[Core]
[[Polymer swelling degree of polymer in core part]]
The core of the particulate polymer is made of a polymer having a predetermined degree of swelling with respect to the electrolytic solution. Specifically, the electrolyte swelling degree of the polymer of the core part needs to be 5 times or more, preferably 7 times or more, more preferably 8 times or more, and 30 It is necessary that it is not more than twice, preferably not more than 28 times, and more preferably not more than 25 times. By setting the electrolyte swelling degree of the polymer in the core part to be equal to or higher than the lower limit of the above range, the functional layer can exhibit high ion diffusibility and the low-temperature output characteristics of the secondary battery can be improved. Moreover, the adhesiveness of the functional layer in electrolyte solution can be improved, and the high temperature cycling characteristic of a secondary battery can be improved by making electrolyte solution swelling degree of the polymer of a core part below the upper limit of the said range.
In the present invention, the “electrolyte swelling degree” of the polymer of the core part can be measured using the measuring method described in the examples of the present specification.

  In addition, as a method of adjusting the electrolyte swelling degree of the polymer of the core part, for example, considering the SP value of the electrolyte solution, the kind and amount of the monomer used for preparing the polymer of the core part Is appropriately selected. Generally, when the SP value of a polymer is close to the SP value of an electrolytic solution, the polymer tends to swell in the electrolytic solution. On the other hand, when the SP value of the polymer is far from the SP value of the electrolytic solution, the polymer tends to hardly swell in the electrolytic solution.

Here, the SP value means a solubility parameter.
The SP value can be calculated using the method introduced in Hansen Solubility Parameters A User's Handbook, 2nd Ed (CRCPless).
Further, the SP value of an organic compound can be estimated from the molecular structure of the organic compound. Specifically, it can be calculated using simulation software (for example, “HSPiP” (http://www.hansen-solubility.com)) that can calculate the SP value from the SMILE equation. In this simulation software, Hansen SOLUBILITY PARAMETERS A User's Handbook Second Edition, Charles M. et al. The SP value is obtained based on the theory described in Hansen.

[[Glass transition temperature of core polymer]]
Further, the glass transition temperature of the polymer constituting the core of the particulate polymer is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and further preferably 5 ° C. or higher. Moreover, it is preferable that it is 150 degrees C or less, It is more preferable that it is 110 degrees C or less, It is more preferable that it is 100 degrees C or less. By setting the glass transition temperature of the polymer in the core part to be equal to or higher than the lower limit of the above range, the adhesion and blocking resistance of the functional layer can be further improved. Moreover, the adhesiveness in the electrolyte solution of a functional layer and the high temperature cycling characteristic of a secondary battery can be improved by making the glass transition temperature of the polymer of a core part below into the upper limit of the said range.

  In addition, as a method of adjusting the glass transition temperature of the polymer of the core part, for example, the type and amount of the monomer used for preparing the polymer of the core part are the same as the homopolymer glass of the monomer. Appropriate selection is considered in consideration of the transition temperature. For example, when a (meth) acrylic acid ester monomer is used for the preparation of the polymer of the core part, the polymer obtained as the carbon number of the part derived from the alcohol of the (meth) acrylic acid ester monomer increases. The glass transition temperature of the glass tends to be low. Here, in the present invention, (meth) acryl means acryl and / or methacryl.

[[Composition of core polymer]]
As a monomer used for preparing the polymer of the core part, a monomer having an electrolyte solution swelling degree within the above range can be appropriately selected and used. Examples of such monomers include vinyl chloride monomers such as vinyl chloride and vinylidene chloride; vinyl acetate monomers such as vinyl acetate; styrene, α-methylstyrene, styrenesulfonic acid, butoxystyrene, Aromatic vinyl monomers such as vinylnaphthalene; vinylamine monomers such as vinylamine; vinylamide monomers such as N-vinylformamide and N-vinylacetamide; methyl acrylate, ethyl acrylate, butyl acrylate, methacryl (Meth) acrylic acid ester monomers such as methyl acrylate, ethyl methacrylate and 2-ethylhexyl acrylate; (meth) acrylamide monomers such as acrylamide and methacrylamide; (meth) acrylonitrile single quantities such as acrylonitrile and methacrylonitrile Body; 2- (perfluorohexyl) ester Fluorine-containing (meth) acrylate monomers such as dimethacrylate and 2- (perfluorobutyl) ethyl acrylate; maleimide; maleimide derivatives such as phenylmaleimide; and diene monomers such as 1,3-butadiene and isoprene; Can be mentioned. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.
In the present invention, (meth) acrylate means acrylate and / or methacrylate, and (meth) acrylonitrile means acrylonitrile and / or methacrylonitrile.

  Among these monomers, it is preferable to use a (meth) acrylic acid ester monomer, and methyl methacrylate and / or butyl acrylate are used as the monomer used for preparing the core polymer. It is more preferable. That is, the polymer of the core part preferably contains a (meth) acrylate monomer unit, and more preferably contains a monomer unit derived from methyl methacrylate and / or butyl acrylate. This makes it easier to control the degree of electrolyte swelling of the polymer in the core and the glass transition temperature of the polymer in the core, and to further increase the ion diffusibility of the functional layer using the particulate polymer. Can do.

  Further, the polymer of the core part may include an acid group-containing monomer unit. Here, as the acid group-containing monomer, a monomer having an acid group, for example, a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, a monomer having a phosphoric acid group, and And monomers having a hydroxyl group.

Examples of the monomer having a carboxylic acid group include monocarboxylic acid and dicarboxylic acid. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid. Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid and the like.
Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth) allyl sulfonic acid, (meth) acrylic acid-2-ethyl sulfonate, 2-acrylamido-2-methyl. Examples thereof include propanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid.
Furthermore, examples of the monomer having a phosphoric acid group include phosphoric acid-2- (meth) acryloyloxyethyl phosphate, methyl-2- (meth) acryloyloxyethyl phosphate, and ethyl phosphate- (meth) acryloyloxyethyl phosphate. Etc.
Examples of the monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.
In the present invention, (meth) allyl means allyl and / or methallyl, and (meth) acryloyl means acryloyl and / or methacryloyl.

Among these, as the acid group-containing monomer, a monomer having a carboxylic acid group is preferable, among which monocarboxylic acid is preferable, and (meth) acrylic acid is more preferable.
Moreover, an acid group containing monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Moreover, the ratio of the acid group content body unit in the polymer of the core part is preferably 0.1% by mass or more, more preferably 1% by mass or more, preferably 20% by mass or less, more preferably 10% by mass. Hereinafter, it is more preferably 7% by mass or less. By keeping the ratio of the acid group-containing unit within the above range, the dispersibility of the polymer in the core part is improved during the preparation of the particulate polymer, and the outer surface of the core part is increased with respect to the outer surface of the core part polymer. A shell portion that partially covers the surface can be easily formed.

  Moreover, it is preferable that the polymer of a core part contains the crosslinkable monomer unit in addition to the said monomer unit. A crosslinkable monomer is a monomer that can form a crosslinked structure during or after polymerization by heating or irradiation with energy rays. By including a crosslinkable monomer unit, the electrolyte solution swelling degree of the polymer can be easily kept within the above range.

  As a crosslinkable monomer, the polyfunctional monomer which has a 2 or more polymerization reactive group in the said monomer is mentioned, for example. Examples of such polyfunctional monomers include divinyl compounds such as divinylbenzene; di (meta) such as ethylene dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butylene glycol diacrylate. ) Acrylic acid ester compounds; Tri (meth) acrylic acid ester compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; Ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate; Is mentioned. Among these, from the viewpoint of easily controlling the degree of swelling of the electrolyte in the polymer of the core part, an ethylenically unsaturated monomer containing a dimethacrylic acid ester compound and an epoxy group is preferred, and a dimethacrylic acid ester compound is more preferred. preferable. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  Here, generally, when the proportion of the crosslinkable monomer unit in the polymer increases, the degree of swelling of the polymer with respect to the electrolytic solution tends to decrease. Therefore, the ratio of the crosslinkable monomer unit is preferably determined in consideration of the type and amount of the monomer used. The specific ratio of the crosslinkable monomer unit in the polymer of the core part is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and further preferably 0.5% by mass or more. Preferably it is 10 mass% or less, More preferably, it is 8 mass% or less, More preferably, it is 6 mass% or less. By setting the ratio of the crosslinkable monomer unit to the lower limit value or more of the above range, the adhesiveness of the functional layer can be enhanced. Moreover, the cycle characteristic of a non-aqueous secondary battery can be improved by making the ratio of a crosslinkable monomer unit below the upper limit of the said range.

[Shell part]
[[Swelling degree of electrolyte in shell polymer]]
The shell part of the particulate polymer is made of a polymer having a predetermined electrolyte solution swelling degree smaller than the electrolyte solution swelling degree of the core part. Specifically, the electrolyte solution swelling degree of the polymer of the shell portion needs to be more than 1 time, preferably 1.1 times or more, more preferably 1.2 times or more. In addition, it is necessary to be 4 times or less, 3.5 times or less is preferable, and 3 times or less is more preferable. By making the electrolyte solution swelling degree of the polymer of the shell part exceed the lower limit value of the above range, the low-temperature output characteristics of the secondary battery can be improved by expressing high ion diffusibility in the functional layer. Moreover, by making the electrolyte solution swelling degree of the polymer of the shell part below the upper limit of the above range, the adhesion between the battery members through the functional layer in the electrolyte solution is improved, and the high temperature cycle characteristics of the secondary battery Can be improved. Further, by making the electrolyte solution swelling degree of the polymer of the shell part within the above range, when the functional layer is formed by using the particulate polymer and the amino acid together, the amino acid is transferred from the functional layer into the electrolytic solution. Elution can also be suppressed.
Here, in this invention, the "electrolyte swelling degree" of the polymer of a shell part can be measured using the measuring method as described in the Example of this specification.

  In addition, as a method for adjusting the electrolyte solution swelling degree of the polymer of the shell part, for example, considering the SP value of the electrolyte solution, the kind and amount of the monomer for producing the polymer of the shell part are determined. Appropriate selection can be mentioned.

[[Glass transition temperature of polymer in shell part]]
The glass transition temperature of the polymer constituting the shell part of the particulate polymer is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 70 ° C. or higher. It is preferably 200 ° C. or lower, more preferably 180 ° C. or lower, and further preferably 150 ° C. or lower. By setting the glass transition temperature of the polymer of the shell part to 50 ° C. or higher, it is possible to suppress the occurrence of blocking between battery members and improve the low-temperature output characteristics of the secondary battery. Moreover, the adhesiveness of a functional layer can further be improved by making the glass transition temperature of the polymer of a shell part into 200 degrees C or less.
Here, the “glass transition temperature” of the polymer of the shell part can be measured using the measuring method described in the examples of the present specification.

  In addition, as a method of adjusting the glass transition temperature of the polymer of the shell part, for example, the type and amount of the monomer used for preparing the polymer of the shell part are the same as the homopolymer glass of the monomer. Appropriate selection is considered in consideration of the transition temperature.

[[Polymer composition of shell part]]
As a monomer used for preparing the polymer of the shell part, a monomer having an electrolyte solution swelling degree within the above range can be appropriately selected and used. Examples of such a monomer include the same monomers as those exemplified as monomers that can be used to produce the core polymer. Moreover, such a monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Among these monomers, it is preferable to use an aromatic vinyl monomer as a monomer used for preparing the polymer of the shell portion. That is, the polymer of the shell part preferably includes an aromatic vinyl monomer unit. Among aromatic vinyl monomers, styrene derivatives such as styrene and styrene sulfonic acid are more preferable. If an aromatic vinyl monomer is used, it is easy to control the degree of electrolyte swelling of the polymer. Moreover, the adhesiveness of the functional layer can be further enhanced.

  And the ratio of the aromatic vinyl monomer unit in the polymer of the shell part is preferably 20% by mass or more, more preferably 40% by mass or more, further preferably 50% by mass or more, and still more preferably 60% by mass or more. Especially preferably, it is 80 mass% or more, Preferably it is 100 mass% or less, More preferably, it is 99.5 mass% or less, More preferably, it is 99 mass% or less. By keeping the ratio of the aromatic vinyl monomer unit in the above range, the degree of swelling of the electrolyte solution and the glass transition temperature of the polymer in the shell part can be easily controlled to a desired range. Moreover, the adhesiveness of the functional layer in electrolyte solution can be improved more.

  Further, the polymer of the shell part may contain an acid group-containing monomer unit in addition to the aromatic vinyl monomer unit. Here, as the acid group-containing monomer, a monomer having an acid group, for example, a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, a monomer having a phosphoric acid group, and And monomers having a hydroxyl group. Specifically, examples of the acid group-containing monomer include monomers similar to the acid group-containing monomer that can be contained in the core portion.

Among these, the acid group-containing monomer is preferably a monomer having a carboxylic acid group, more preferably a monocarboxylic acid, and even more preferably (meth) acrylic acid.
Moreover, an acid group containing monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The ratio of the acid group-containing monomer unit in the polymer of the shell part is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 3% by mass or more, and preferably 20% by mass. Hereinafter, it is more preferably 10% by mass or less, and further preferably 7% by mass or less. By keeping the ratio of the acid group-containing monomer unit within the above range, the dispersibility of the particulate polymer in the functional layer can be improved, and good adhesiveness can be expressed over the entire functional layer.

  Further, the polymer of the shell part may contain a crosslinkable monomer unit. Examples of the crosslinkable monomer include monomers similar to those exemplified as the crosslinkable monomer that can be used in the core polymer. Moreover, a crosslinking | crosslinked monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  And the ratio of the crosslinkable monomer unit in the polymer of the shell part is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, further preferably 0.5% by mass or more, preferably Is 5% by mass or less, more preferably 4% by mass or less, and still more preferably 3% by mass or less.

[[Shell configuration]]
The form of the shell part is not particularly limited, but the shell part is preferably composed of polymer particles. When the shell part is constituted by polymer particles, a plurality of particles constituting the shell part may overlap in the radial direction of the particulate polymer. However, in the radial direction of the particulate polymer, it is preferable that the particles constituting the shell portion do not overlap each other and the particles of the polymer constitute the shell portion as a single layer.

[Preparation method of particulate polymer]
And the particulate polymer which has the core shell structure mentioned above uses the monomer of the polymer of a core part, and the monomer of the polymer of a shell part, for example, The ratio of those monomers with time It can be prepared by polymerizing stepwise while changing. Specifically, the particulate polymer can be prepared by a continuous multi-stage emulsion polymerization method and a multi-stage suspension polymerization method in which the polymer of the previous stage is sequentially coated with the polymer of the subsequent stage. it can.

  Then, an example in the case of obtaining the particulate polymer which has the said core shell structure by a multistage emulsion polymerization method below is shown.

  In the polymerization, according to a conventional method, as an emulsifier, for example, an anionic surfactant such as sodium dodecylbenzenesulfonate and sodium dodecylsulfate, a nonionic surfactant such as polyoxyethylene nonylphenyl ether and sorbitan monolaurate, or Cationic surfactants such as octadecylamine acetate can be used. Examples of the polymerization initiator include peroxides such as t-butylperoxy-2-ethylhexanoate, potassium persulfate, cumene peroxide, 2,2′-azobis (2-methyl-N- (2 An azo compound such as (hydroxyethyl) -propionamide) or 2,2′-azobis (2-amidinopropane) hydrochloride can be used.

  And as a polymerization procedure, the monomer and emulsifier which form a core part are mixed first, and the particulate polymer which comprises a core part is obtained by carrying out emulsion polymerization collectively. Furthermore, the particulate polymer which has the core shell structure mentioned above can be obtained by superposing | polymerizing the monomer which forms a shell part in presence of the particulate polymer which comprises this core part.

  At this time, from the viewpoint of partially covering the outer surface of the core portion with the shell portion, the monomer that forms the polymer of the shell portion is divided into a plurality of times or continuously supplied to the polymerization system. Is preferred. The monomer that forms the polymer of the shell part is divided into a polymerization system or continuously supplied, whereby the polymer constituting the shell part is formed into particles, and these particles are bonded to the core part. Thereby, the shell part which covers a core part partially can be formed.

  In addition, when supplying the monomer which forms the polymer of a shell part divided | segmented into multiple times, it is possible to control the average thickness of a shell part according to the ratio which divides | segments a monomer. In addition, when continuously supplying the monomer that forms the polymer of the shell part, it is possible to control the average thickness of the shell part by adjusting the monomer supply amount per unit time. is there.

  Moreover, the volume average particle diameter D50 of the particulate polymer after forming the shell part can be set to a desired range by adjusting, for example, the amount of the emulsifier and the amount of the monomer. Furthermore, the average ratio (coverage) by which the outer surface of the core part is covered by the shell part is adjusted by, for example, adjusting the amount of the emulsifier and the amount of the monomer that forms the polymer of the shell part. Can range.

<Amino acid>
The composition for a non-aqueous secondary battery functional layer of the present invention contains an amino acid together with the particulate polymer. The amino acid contained in the non-aqueous secondary battery functional layer composition has a function of improving the dispersibility of the particulate polymer in the functional layer composition and in the functional layer. And by improving the dispersibility of the particulate polymer, the adhesion of the functional layer formed using the composition for a non-aqueous secondary battery functional layer is improved, and the high-temperature cycle characteristics of the secondary battery are further improved. Can be.

  In the present invention, amino acids that can be dissolved in the composition for a non-aqueous secondary battery functional layer can be appropriately selected and used as the amino acid. An amino acid is an organic compound having an amino group and a carboxyl group in one molecule, and there are α-amino acids, β-amino acids, γ-amino acids, and δ-amino acids depending on the carbon position where the amino group and the carboxyl group are bonded. To do. In the present invention, any one can be used, but it is preferable to use an α-amino acid from the viewpoint of availability. In addition, D-type and L-type stereoisomers exist in the α-amino acid excluding glycine. In the present invention, either one of them or a mixture of both can be used.

  Examples of the amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine and the like. It is done. In addition, an amino acid may be used independently and may be used in combination of 2 or more types.

  From the viewpoint of solubility and stability, the number of carbon atoms per molecule of the amino acid is preferably 2 or more, more preferably 3 or more, further preferably 4 or more, and 10 or less. Preferably, it is 9 or less, more preferably 8 or less. In addition, as the amino acid, an amino acid having two carboxyl groups in one molecule (acidic amino acid) is preferably used, and aspartic acid and / or glutamic acid is more preferably used. This improves the dispersibility of the particulate polymer without hindering the function of the functional layer formed using the non-aqueous secondary battery functional layer composition or the function of the secondary battery including the functional layer. A functional layer having excellent adhesiveness can be provided.

  The content of amino acid in the composition for a non-aqueous secondary battery functional layer of the present invention is such that the ratio of amino acid is 0.1 parts by mass or more with respect to 100 parts by mass of the particulate polymer, and 0.5 mass Part or more, preferably 0.8 part by weight or more, more preferably 5 parts by weight or less, preferably 4 parts by weight or less, and 3 parts by weight or less. Is more preferable. By making content of an amino acid more than the lower limit of the said range, the dispersibility of the particulate polymer in the composition for non-aqueous secondary battery functional layers can be improved. As a result, the functional layer can be formed uniformly, and the adhesiveness of the functional layer and the high-temperature cycle characteristics of the secondary battery including the functional layer can be improved. In addition, by setting the content of amino acids below the upper limit of the above range, the amount of amino acids contained in the functional layer is set to an appropriate range, and excessive amino acids are decomposed when the secondary battery is used. It can prevent that battery characteristics, such as a high temperature cycling characteristic, fall.

<Binder for functional layer>
Here, as described above, the particulate polymer is not swollen in the electrolytic solution, and usually does not exhibit great adhesiveness when not heated. Therefore, from the viewpoint of suppressing the particulate polymer from falling off the functional layer immediately after the formation of the functional layer (before heating or immersion in the electrolytic solution), the functional layer composition swells in the electrolytic solution. In addition, it is preferable to include a functional layer binder that exhibits adhesiveness even in an unheated state. By using the binder for the functional layer, it is possible to suppress the components such as the particulate polymer from falling off the functional layer even when the electrolyte is not swollen and not heated. .

The functional layer binder that can be used in combination with the particulate polymer includes known binders that are water-insoluble and dispersible in a dispersion medium such as water, such as thermoplastic elastomers. And as a thermoplastic elastomer, a conjugated diene polymer and an acrylic polymer are preferable, and an acrylic polymer is more preferable.
Here, the conjugated diene polymer refers to a polymer containing a conjugated diene monomer unit. Specific examples of the conjugated diene polymer include aromatic vinyl such as styrene-butadiene copolymer (SBR). Examples thereof include a polymer containing a monomer unit and an aliphatic conjugated diene monomer unit, and an acrylic rubber (NBR) (a polymer containing an acrylonitrile unit and a butadiene unit). Moreover, an acrylic polymer refers to the polymer containing a (meth) acrylic acid ester monomer unit. Here, the (meth) acrylic acid ester monomer that can form a (meth) acrylic acid ester monomer unit is the same as the monomer used for preparing the core polymer of the particulate polymer. Can be used.
These functional layer binders may be used alone or in combination of two or more. However, when a functional layer binding material in which two or more kinds of polymers are combined is used, the polymer as the functional layer binding material is a particulate polymer having a core-shell structure made of the above-mentioned predetermined polymer. Is different.

  Furthermore, it is more preferable that the acrylic polymer as the functional layer binder contains a (meth) acrylonitrile monomer unit. Thereby, the intensity | strength of a functional layer can be raised.

  Here, in the acrylic polymer as the binder for the functional layer, the amount of the (meth) acrylonitrile monomer unit relative to the total amount of the (meth) acrylonitrile monomer unit and the (meth) acrylic acid ester monomer unit The ratio is preferably 1% by mass or more, more preferably 2% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less. By setting the ratio to be equal to or higher than the lower limit of the range, the strength of the acrylic polymer as the binder for the functional layer can be increased, and the strength of the functional layer using the acrylic polymer can be further increased. . Moreover, since the acrylic polymer as the binder for the functional layer is appropriately swollen with respect to the electrolytic solution by setting the ratio to be not more than the upper limit of the above range, the ion conductivity of the functional layer is reduced. A decrease in the low-temperature output characteristics of the secondary battery can be suppressed.

  The glass transition temperature of the functional layer binder is preferably −100 ° C. or higher, more preferably −90 ° C. or higher, further preferably −80 ° C. or higher, and preferably 0 ° C. or lower. More preferably, it is -5 degrees C or less, More preferably, it is -10 degrees C or less. By making the glass transition temperature of the functional layer binder higher than the lower limit of the above range, the adhesiveness and strength of the functional layer binder can be enhanced. Moreover, the softness | flexibility of a functional layer can be improved by making the glass transition temperature of the binder for functional layers below into the upper limit of the said range.

  Furthermore, the volume average particle diameter D50 of the functional layer binder is preferably 0.1 μm or more and 0.5 μm or less. By setting the volume average particle diameter D50 of the binder for functional layers to be equal to or greater than the lower limit of the above range, the dispersibility of the binder for functional layers can be enhanced. Moreover, the adhesiveness of the binder for functional layers can be improved by making volume average particle diameter D50 below the upper limit of the said range.

  The content of the functional layer binder in the functional layer composition is preferably 1 part by mass or more and preferably 5 parts by mass or more with respect to 100 parts by mass of the particulate polymer described above. Is more preferable, and it is preferably 30 parts by mass or less, and more preferably 25 parts by mass or less. By making the content of the binder for the functional layer more than the lower limit of the above range, the binding property of the functional layer is improved, and the particulate polymer is dropped from the functional layer before heating or immersion in the electrolytic solution. Can be sufficiently prevented. Moreover, the fall of the ion conductivity of a functional layer and the low-temperature output characteristic of a secondary battery can be suppressed by making content of the binder for functional layers into below the upper limit of the said range.

  Examples of the method for producing the functional layer binder include a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these, the emulsion polymerization method and the suspension polymerization method can be polymerized in water, and an aqueous dispersion containing a particulate functional layer binder can be suitably used as a material for the functional layer composition as it is. preferable. Moreover, when manufacturing the polymer as a binder for functional layers, it is preferable that the reaction system contains a dispersing agent. The functional layer binder is usually formed of a polymer substantially constituting the functional layer binder, but may be accompanied by optional components such as additives used in the polymerization.

<Non-conductive particles>
Furthermore, when the functional layer also functions as a porous membrane layer, the functional layer composition may contain non-conductive particles. The non-conductive particles to be blended in the functional layer composition are not particularly limited, and known non-conductive particles used for non-aqueous secondary batteries can be exemplified.
Specifically, as the non-conductive particles, both inorganic fine particles and organic fine particles other than the above-described particulate polymer and functional layer binder can be used, but inorganic fine particles are usually used. . Especially, as a material of nonelectroconductive particle, the material which exists stably in the use environment of a non-aqueous secondary battery and is electrochemically stable is preferable. From this point of view, preferable examples of the non-conductive particle material include aluminum oxide (alumina), hydrated aluminum oxide (boehmite), silicon oxide, magnesium oxide (magnesia), calcium oxide, titanium oxide (titania). Oxide particles such as BaTiO ₃ , ZrO, alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; covalently bonded crystal particles such as silicon and diamond; barium sulfate, calcium fluoride, barium fluoride Insoluble ion crystal particles such as; clay fine particles such as talc and montmorillonite; In addition, these particles may be subjected to element substitution, surface treatment, solid solution, and the like as necessary.
In addition, the nonelectroconductive particle mentioned above may be used individually by 1 type, and may be used in combination of 2 or more types.

<Other ingredients>
And the composition for non-aqueous secondary battery functional layers may contain arbitrary other components besides the component mentioned above. The other components are not particularly limited as long as they do not affect the battery reaction, and known components can be used. Moreover, these other components may be used individually by 1 type, and may be used in combination of 2 or more types.
Examples of the other components include known additives such as a wetting agent such as an ethylene oxide-propylene oxide copolymer, a viscosity modifier, and an electrolyte solution additive.

<Preparation of non-aqueous secondary battery functional layer composition>
The method for preparing the composition for the functional layer is not particularly limited, but is usually a particulate polymer, an amino acid, water as a dispersion medium, a functional layer binder used as necessary, and a non-conductive material. The functional layer composition is prepared by mixing the functional particles and other components. Although the mixing method is not particularly limited, in order to disperse each component efficiently, mixing is usually performed using a disperser as a mixing device.
As the disperser, it is preferable to use an apparatus capable of uniformly dispersing and mixing the above components. Examples include a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, and a planetary mixer. From the viewpoint that a high dispersion share can be added, it is also preferable to use a high dispersion apparatus such as a bead mill, a roll mill, or a fill mix.

(Functional layer for non-aqueous secondary batteries)
The functional layer for a non-aqueous secondary battery can be formed on an appropriate base material using the composition for a non-aqueous secondary battery functional layer described above. And the base material with a functional layer for non-aqueous secondary batteries is obtained by forming a functional layer on a base material. Here, the functional layer for a non-aqueous secondary battery formed on this base material is excellent in blocking resistance, can exhibit excellent adhesiveness even after being immersed in an electrolytic solution, and non- Excellent battery characteristics (such as high-temperature cycle characteristics and low-temperature output characteristics) can be exhibited in water-based secondary batteries.

<Base material>
The type of the base material for forming the functional layer is not particularly limited. For example, when the functional layer is used as a member constituting a part of the separator, the separator base material can be used as the base material. When a functional layer is used as a member constituting a part, an electrode base material formed by forming an electrode mixture layer on a current collector can be used as the base material. Moreover, there is no restriction | limiting in particular in the usage of the base material with a functional layer obtained by forming a functional layer on a base material using the composition for non-aqueous secondary battery functional layers, for example, a functional layer on a separator base material etc. May be used directly as a battery member such as a separator, or may be used as an electrode by forming a functional layer on an electrode substrate, or a functional layer formed on a release substrate. It may be peeled once from the mold release substrate and attached to another substrate to be used as a battery member.
However, from the viewpoint of increasing the production efficiency of the battery member by omitting the step of peeling the release substrate from the functional layer, a separator substrate or an electrode substrate is used as the substrate, and the substrate with the functional layer is used as the battery member. It is preferable to use it as it is. Since the functional layer formed on the separator base material or the electrode base material contains the above-mentioned particulate polymer, it exhibits blocking resistance. In addition, the functional layer can exhibit excellent adhesiveness in the electrolytic solution and can improve the battery characteristics of the secondary battery.

[Separator substrate]
As a separator base material which forms a functional layer, it does not specifically limit, For example, the thing of Unexamined-Japanese-Patent No. 2012-204303 can be used. Among these, the film thickness of the entire separator can be reduced, thereby increasing the ratio of the electrode active material in the secondary battery and increasing the capacity per volume. A microporous film made of a resin such as polyethylene, polypropylene, polybutene, or polyvinyl chloride is preferable.
In addition, the separator base material may contain an arbitrary layer that can exhibit an intended function other than the functional layer.

[Electrode substrate]
Although it does not specifically limit as an electrode base material (a positive electrode base material and a negative electrode base material) which forms a functional layer, The electrode base material with which the electrode compound-material layer was formed on the electrical power collector is mentioned.
Here, the current collector, the components in the electrode mixture layer (for example, the electrode active material (positive electrode active material, negative electrode active material) and the electrode mixture layer binder (positive electrode mixture layer binder, negative electrode composite) As a method for forming the electrode mixture layer on the current collector, and the like, a known material can be used. Specifically, for example, those described in JP2013-145663A can be used.
In addition, the electrode base material may include an arbitrary layer having an intended function other than the functional layer in a part thereof.

[Release substrate]
It does not specifically limit as a mold release base material which forms a functional layer, A known mold release base material can be used.

<Method for forming functional layer for non-aqueous secondary battery>
Examples of the method for forming a functional layer on a substrate such as the separator substrate or electrode substrate described above include the following methods:
1) A method in which the composition for a functional layer is applied to the surface of a separator substrate or an electrode substrate (in the case of an electrode substrate, the surface on the electrode mixture layer side, the same shall apply hereinafter) and then dried;
2) A method of drying a separator substrate or electrode substrate after immersing the separator layer or electrode substrate in the functional layer composition;
3) A method for producing a functional layer by applying and drying a composition for a functional layer on a release substrate, and transferring the obtained functional layer to the surface of a separator substrate or an electrode substrate.
Among these, the method 1) is particularly preferable because the thickness of the functional layer can be easily controlled. Specifically, the method 1) includes a step of applying a functional layer composition on a separator substrate or an electrode substrate (application step), and a function layer applied on the separator substrate or the electrode substrate. A step of drying the composition to form a functional layer (drying step) is provided.

In the coating process, the method for coating the functional layer composition on the separator substrate or the electrode substrate is not particularly limited. For example, spray coating method, doctor blade method, reverse roll method, direct roll method, gravure method, Examples include an extrusion method and a brush coating method. Of these, the gravure method and the spray coating method are preferable from the viewpoint of forming a thinner functional layer.
In the drying step, the method for drying the composition for the functional layer on the substrate is not particularly limited, and a known method can be used. For example, drying with warm air, hot air, low-humidity air, vacuum drying, infrared rays, A drying method by irradiation with an electron beam or the like can be mentioned. The drying conditions are not particularly limited, but the drying temperature is preferably 30 to 80 ° C., and the drying time is preferably 30 seconds to 10 minutes.

  The thickness of the functional layer formed on the substrate is preferably 0.01 μm or more, more preferably 0.1 μm or more, further preferably 0.5 μm or more, preferably 20 μm or less, more preferably 10 μm or less. More preferably, it is 5 μm or less. When the thickness of the functional layer is not less than the lower limit value of the range, the strength of the functional layer can be sufficiently secured, and by being not more than the upper limit value of the range, the ion diffusibility of the functional layer is ensured. The low temperature output characteristics of the secondary battery can be further improved.

(Non-aqueous secondary battery)
The non-aqueous secondary battery of the present invention includes the above-described functional layer for a non-aqueous secondary battery. Specifically, the non-aqueous secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolytic solution, and at least one of the positive electrode, the negative electrode, and the separator includes the functional layer for the non-aqueous secondary battery. It consists of a base material with a functional layer for non-aqueous secondary batteries. And in the non-aqueous secondary battery of this invention, when the said functional layer for non-aqueous secondary batteries functions as an adhesive layer, a positive electrode and a separator and / or a negative electrode and a separator are adhere | attached through a functional layer. The The non-aqueous secondary battery of the present invention includes a battery member including a functional layer formed using the composition for a non-aqueous secondary battery functional layer of the present invention. Since the material and the battery members are firmly bonded even in the electrolytic solution, the battery characteristics such as high-temperature cycle characteristics are excellent.

  In the non-aqueous secondary battery, as the positive electrode, negative electrode, and separator that do not have the above-described non-aqueous secondary battery functional layer, the known positive electrode, negative electrode, and separator used in the non-aqueous secondary battery are used. can do. As the electrolytic solution, a known electrolytic solution used in a non-aqueous secondary battery can be used.

  Specifically, as the electrode (positive electrode and negative electrode) that does not have the above-described non-aqueous secondary battery functional layer, the above-described electrode base material can be used, and the above-described non-aqueous secondary battery functional layer is The separator base material mentioned above can be used as a separator which does not have.

As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. For example, when the non-aqueous secondary battery is a lithium ion secondary battery, a lithium salt is used as the supporting electrolyte. Examples of the lithium salt include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi , (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ ) NLi, and the like. Of these, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li are preferable, and LiPF ₆ is particularly preferable because it is easily dissolved in a solvent and exhibits a high degree of dissociation. In addition, electrolyte may be used individually by 1 type and may be used combining two or more types by arbitrary ratios. Usually, the lithium ion conductivity tends to increase as the supporting electrolyte having a higher degree of dissociation is used, so that the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.

Furthermore, the organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. For example, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC) ), Carbonates such as butylene carbonate (BC) and ethyl methyl carbonate (EMC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; including sulfolane and dimethyl sulfoxide Sulfur compounds; etc. are preferably used. Moreover, you may use the liquid mixture of these solvents. Among them, it is preferable to use carbonates because they have a high dielectric constant and a wide stable potential region, and it is more preferable to use a mixture of ethylene carbonate and ethyl methyl carbonate.
In addition, the density | concentration of the electrolyte in electrolyte solution can be adjusted suitably, for example, it is preferable to set it as 0.5-15 mass%, it is more preferable to set it as 2-13 mass%, and it shall be 5-10 mass%. Is more preferable. Further, known additives such as fluoroethylene carbonate and ethyl methyl sulfone may be added to the electrolytic solution.

<Method for producing non-aqueous secondary battery>
The non-aqueous secondary battery is, for example, a structure in which a positive electrode and a negative electrode are stacked with a separator interposed between them, and if necessary, wound or folded according to the shape of the battery and put into a battery container. Can be manufactured by injecting and sealing. In order to prevent the occurrence of pressure rise inside the non-aqueous secondary battery, overcharge / discharge, etc., an overcurrent prevention element such as a fuse or a PTC element, an expanded metal, a lead plate, etc. may be provided as necessary. . The shape of the non-aqueous secondary battery may be any of a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, and the like, for example.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the following description, “%” and “part” representing amounts are based on mass unless otherwise specified.
In addition, in a polymer produced by copolymerizing a plurality of types of monomers, the proportion of the structural unit formed by polymerizing a certain monomer in the polymer is usually that unless otherwise specified. This coincides with the ratio (preparation ratio) of the certain monomer in the total monomers used for polymerization of the polymer.
In Examples and Comparative Examples, the electrolyte swelling degree and glass transition temperature of the core polymer and the shell polymer, the glass transition temperature of the functional layer binder, the particulate polymer, and the functional layer binder Volume average particle diameter D50, core-shell ratio and coverage of particulate polymer, dispersibility of composition for non-aqueous secondary battery functional layer, adhesion between electrode and separator after immersion in electrolyte, and secondary battery The high-temperature cycle characteristics and low-temperature output characteristics were measured and evaluated by the following methods.

<Swelling degree of electrolyte solution of polymer of core part and polymer of shell part>
Using the monomers and various additives used for forming the core and shell of the particulate polymer, the polymer and shell of the core are polymerized under the same polymerization conditions as those of the core and shell. An aqueous dispersion containing part of the polymer was prepared. This aqueous dispersion was put into a petri dish made of polytetrafluoroethylene and dried under conditions of 25 ° C. and 48 hours to obtain a film having a thickness of 0.5 mm. And the obtained film was cut | judged to 1 square cm, and the test piece was obtained. The mass W0 of this test piece was measured. Further, the test piece was immersed in an electrolytic solution at 60 ° C. for 72 hours. Then, the test piece was taken out from the electrolytic solution, the electrolytic solution on the surface of the test piece was wiped off, and the mass W1 of the test piece after the immersion test was measured. And using these mass W0 and W1, electrolyte solution swelling degree S (times) was calculated | required by S = W1 / W0.
As the electrolytic solution, a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and vinylene carbonate (VC) (volume mixing ratio: EC / DEC / VC = 68.5 / 30 / 1.5; SP Value: 12.7 (cal / cm ³ ) ^1/2 ) was used as a supporting electrolyte in which LiPF ₆ was dissolved in a solvent at a concentration of 1 mol / L.

<Glass transition temperature of core polymer, shell polymer and functional layer binder>
Polymer used as a measurement sample under the same polymerization conditions as the polymerization conditions of the core part and the shell part using the monomers and various additives used for the formation of the core part and the shell part of the particulate polymer ( A water dispersion containing a core polymer and a shell polymer) was prepared. The prepared aqueous dispersion was used as a measurement sample. Moreover, the aqueous dispersion containing the binder for functional layers was prepared, and it was set as the measurement sample.
Next, using a differential thermal analysis measuring device (product name “EXSTAR DSC6220” manufactured by SII Nano Technology Co., Ltd.), 10 mg of the dried measurement sample is weighed on an aluminum pan, and an empty aluminum pan is used as a reference. The DSC curve was measured in a temperature range of −100 ° C. to 500 ° C. at a temperature rising rate of 10 ° C./min and at normal temperature and humidity. During this temperature rising process, the baseline immediately before the endothermic peak of the DSC curve where the differential signal (DDSC) becomes 0.05 mW / min / mg or more and the tangent line of the DSC curve at the first inflection point after the endothermic peak The glass transition temperature was determined from the intersection with.

<Volume average particle diameter D50 of binder for functional polymer and functional layer>
The volume average particle diameter D50 of the particulate polymer and the functional layer binder is determined from the small diameter side in the particle diameter distribution measured by a laser diffraction particle size distribution measuring device ("SALD-3100" manufactured by Shimadzu Corporation). The particle diameter was such that the calculated cumulative volume was 50%.

<Core-shell ratio of particulate polymer>
The core-shell ratio of the particulate polymer was measured by the following procedure.
The prepared particulate polymer was sufficiently dispersed in a visible light curable resin (“D-800” manufactured by JEOL Ltd.) and then embedded to obtain a block piece containing the particulate polymer. Next, the obtained block piece was cut into a thin piece having a thickness of 100 nm with a microtome equipped with a diamond blade to prepare a measurement sample. Thereafter, the measurement sample was dyed using ruthenium tetroxide.
Next, the dyed measurement sample was set in a transmission electron microscope (“JEM-3100F” manufactured by JEOL Ltd.), and the cross-sectional structure of the particulate polymer was photographed at an acceleration voltage of 80 kV. . The magnification of the electron microscope was set so that the cross section of one particulate polymer was in the visual field. Thereafter, the cross-sectional structure of the photographed particulate polymer was observed, and the average thickness of the shell portion of the particulate polymer was measured by the following procedure according to the observed configuration of the shell portion. And the core-shell ratio was calculated | required by dividing the measured average thickness of the shell part by the volume average particle diameter D50 of a particulate polymer.
<< When the shell part is composed of polymer particles >>
From the cross-sectional structure of the particulate polymer, the longest diameter of the polymer particles constituting the shell portion was measured. The longest diameter of the polymer particles constituting the shell portion was measured for 20 arbitrarily selected particulate polymers, and the average value of the longest diameters was taken as the average thickness of the shell portion.
<< When the shell has a shape other than particles >>
The maximum thickness of the shell portion was measured from the cross-sectional structure of the particulate polymer. The maximum thickness of the shell part was measured for 20 arbitrarily selected particulate polymers, and the average value of the maximum thickness was taken as the average thickness of the shell part.

<Particulate polymer coverage>
The coverage of the particulate polymer was measured by the following procedure.
In the same manner as the method for measuring the core-shell ratio of the particulate polymer, a cross-sectional structure of the particulate polymer is photographed. In the photographed cross-sectional structure of the particulate polymer, the circumference D1 of the core portion, and The length D2 of the part where the outer surface of the core part and the shell part contact each other is measured, and the ratio of the outer surface of the core part of the particulate polymer covered by the shell part (covering ratio) Rc (%) = ( D2 / D1) × 100 was calculated. For the calculation of the covering ratio Rc, “AnalySIS Pro” (manufactured by Olympus Corporation) which is image analysis software was used.
The covering ratio Rc is measured for 20 arbitrarily selected particulate polymers, and the average value is the average ratio (covering ratio) at which the outer surface of the core part of the particulate polymer is covered by the shell part. did.

<Dispersibility of composition for functional layer of non-aqueous secondary battery>
The produced composition for a non-aqueous secondary battery functional layer having a solid content concentration of C is enclosed in a settling tube by a mass w0, and is centrifuged using a centrifuge at a centrifugal acceleration of 700 G and a processing time of 6 h to obtain particles. The polymer was forced to settle. Next, the settling tube was set on a shaker, and shaken under the conditions of a shaking speed of 80 min ⁻¹ and a shaking time of 12 hours, and the particulate polymer and the like were redispersed. The contents of the settling tube obtained by the above treatment are passed through a wire mesh (200 mesh), and the wire mesh and the residue on the wire mesh are dried in an oven at 105 ° C. for 30 minutes, and then the residue on the wire mesh. The weight w1 of was measured. And the residue density | concentration w (ppm) = w1 / (w0 * C) * 1000000 was computed, and the dispersibility of the composition for functional layers was evaluated on the following reference | standard. The smaller the value of W, the better the dispersibility of the particulate polymer and the like in the composition for the non-aqueous secondary battery functional layer, and the particulate polymer and the like are aggregated in the composition for the non-aqueous secondary battery functional layer. It shows that the ratio which exists is small.
A: Residual concentration w is less than 300 ppm B: Residual concentration w is 300 ppm or more and less than 1000 ppm C: Residual concentration w is 1000 ppm or more

<Adhesiveness between separator and electrode after immersion in electrolyte>
The prepared laminate including the positive electrode and the separator and the laminate including the negative electrode and the separator were each cut into a width of 10 mm to obtain test pieces. This test piece was immersed in the electrolytic solution at a temperature of 60 ° C. for 3 days. Here, as the electrolytic solution, a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and vinylene carbonate (VC) (volume mixing ratio: EC / DEC / VC = 68.5 / 30 / 1.5; SP value: 12.7 (cal / cm ³ ) ^1/2 ) was used as a supporting electrolyte in which LiPF ₆ was dissolved in a solvent at a concentration of 1 mol / L.
Then, the test piece was taken out and the electrolytic solution adhering to the surface was wiped off. Then, the cellophane tape was affixed on the surface of the electrode of this test piece with the current collector side of the electrode (positive electrode or negative electrode) facing down. At this time, a cellophane tape defined in JIS Z1522 was used. The cellophane tape was fixed on a horizontal test bench. And the stress when one end of the separator base material was pulled vertically upward at a pulling speed of 50 mm / min and peeled was measured. This measurement was performed three times for each of the laminate including the positive electrode and the separator, and the laminate including the negative electrode and the separator, for a total of 6 times, and the average value of the stress was obtained as the peel strength. And the separator base material were evaluated according to the following criteria. It shows that adhesiveness is so high that peel strength is large.
A: Peel strength is 5.0 N / m or more B: Peel strength is 3.0 N / m or more and less than 5.0 N / m C: Peel strength is 0.5 N / m or more and less than 3.0 N / m D: Peel strength is Less than 0.5 N / m

<High temperature cycle characteristics>
The manufactured lithium ion secondary battery of a wound type cell having a discharge capacity of 800 mAh was allowed to stand in an environment of 25 ° C. for 24 hours. Thereafter, under an environment of 25 ° C., a charge / discharge operation of charging up to 4.35 V at 0.1 C and discharging to 2.75 V at 0.1 C was performed, and the initial capacity C0 was measured. Thereafter, charging and discharging were further repeated under the same conditions as described above under an environment of 60 ° C., and the capacity C1 after 1000 cycles was measured. Then, the capacity retention ratio ΔC (%) = (C1 / C0) × 100 before and after the cycle was calculated, and the high temperature cycle characteristics were evaluated according to the following criteria. The larger the value of the capacity retention ratio ΔC, the better the high-temperature cycle characteristics and the longer the battery life.
A: Capacity maintenance ratio ΔC is 84% or more B: Capacity maintenance ratio ΔC is 80% or more and less than 84% C: Capacity maintenance ratio ΔC is 75% or more and less than 80% D: Capacity maintenance ratio ΔC is less than 75%

<Low temperature output characteristics>
The manufactured lithium ion secondary battery of a wound type cell having a discharge capacity of 800 mAh was allowed to stand in an environment of 25 ° C. for 24 hours. Thereafter, charging was performed for 5 hours at a charging rate of 0.1 C under an environment of 25 ° C., and the voltage V0 at that time was measured. Thereafter, a discharge operation was performed at a discharge rate of 1 C in a -10 ° C environment, and the voltage V1 15 seconds after the start of discharge was measured. And voltage change (DELTA) V = V0-V1 was computed, and the low-temperature output characteristic was evaluated on the following reference | standard. It shows that it is excellent in low temperature output characteristics, so that the value of this voltage change (DELTA) V is small.
A: Voltage change ΔV is less than 350 mV B: Voltage change ΔV is 350 mV or more and less than 500 mV C: Voltage change ΔV is 500 mV or more and less than 650 mV D: Voltage change ΔV is 650 mV or more

Example 1
<Preparation of particulate polymer having core-shell structure>
In a 5 MPa pressure vessel with a stirrer, 75 parts of methyl methacrylate as a (meth) acrylic acid ester monomer, 4 parts of methacrylic acid as an acid group-containing monomer, 1 part of ethylene glycol dimethacrylate; 1 part of sodium dodecylbenzenesulfonate as an emulsifier; 150 parts of ion-exchanged water and 0.5 part of potassium persulfate as a polymerization initiator were added and sufficiently stirred. Then, it heated to 60 degreeC and superposition | polymerization was started. Polymerization was continued until the polymerization conversion rate reached 96% to obtain an aqueous dispersion containing a particulate polymer constituting the core portion.

To this aqueous dispersion, a mixture of 19 parts of styrene as an aromatic vinyl monomer and 1 part of methacrylic acid as an acid group-containing monomer was continuously added to form a shell part, and heated to 70 ° C. Polymerization was continued. When the polymerization conversion rate reaches 96%, the reaction is stopped by cooling, and an aqueous dispersion containing a particulate polymer having a core-shell structure in which the outer surface of the core part is partially covered with the shell part. Prepared.
In addition, the volume average particle diameter D50 of the obtained particulate polymer was 0.45 μm.
Then, the core-shell ratio and the coverage of the obtained particulate polymer were evaluated. The results are shown in Table 1.

<Preparation of functional layer binder>
In a reactor equipped with a stirrer, 70 parts of ion-exchanged water, 0.15 part of sodium lauryl sulfate (product name “Emal 2F” manufactured by Kao Chemical Co., Ltd.) as an emulsifier, and 0.5 part of ammonium persulfate, Each was supplied, the gas phase was replaced with nitrogen gas, and the temperature was raised to 60 ° C.
On the other hand, in a separate container, 50 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate as a dispersant, 94 parts of butyl acrylate as a (meth) acrylate monomer, 2 parts of acrylonitrile, 2 parts of methacrylic acid, 1 part of N-methylolacrylamide and 1 part of acrylamide were mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours for polymerization. During the addition, the reaction was carried out at 60 ° C. After completion of the addition, the reaction was terminated by further stirring at 70 ° C. for 3 hours to prepare an aqueous dispersion containing the functional layer binder.
In addition, the volume average particle diameter D50 of the obtained binder for functional layers was 0.36 micrometer, and the glass transition temperature was -40 degreeC.

<Preparation of non-aqueous secondary battery functional layer composition>
The aqueous dispersion containing the particulate polymer having the core-shell structure is equivalent to 100 parts in solids, and the aqueous dispersion containing the functional layer binder is equivalent to 22 parts in solids, L as an amino acid. -1 part of aspartic acid corresponding to solid content, and 2 parts of ethylene oxide-propylene oxide copolymer (solid content concentration 70 mass%, polymerization ratio: 5/5 (mass ratio)) as a wetting agent Further, ion-exchanged water was mixed so that the solid content concentration was 20% by mass to prepare a slurry-like composition for a non-aqueous secondary battery functional layer. The dispersibility of the composition for a non-aqueous secondary battery functional layer thus obtained was measured by the method described above. The results are shown in Table 1.

<Preparation of separator>
A porous substrate made of polyethylene (thickness 16 μm, Gurley value 210 s / 100 cc) was prepared as a separator substrate. On both surfaces of the prepared separator base material, the functional layer composition was applied by a spray coating method and dried at 50 ° C. for 1 minute. As a result, a functional layer having a thickness of 1 μm per layer was formed on the separator substrate, and a separator formed by forming functional layers on both sides of the separator substrate was obtained. This separator includes a functional layer, a separator base material, and a functional layer in this order.

<Manufacture of particulate binder for negative electrode>
In a 5 MPa pressure vessel with a stirrer, 33.5 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 62 parts of styrene, 1 part of 2-hydroxyethyl acrylate, 0.4 part of sodium dodecylbenzenesulfonate as an emulsifier, ions After adding 150 parts of exchange water and 0.5 part of potassium persulfate as a polymerization initiator and stirring sufficiently, the mixture was heated to 50 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing a particulate binder (SBR). A 5% aqueous sodium hydroxide solution was added to the mixture containing the particulate binder to adjust the pH to 8. Thereafter, unreacted monomers are removed from the mixture by heating under reduced pressure, and the mixture is cooled to 30 ° C. or lower to obtain an aqueous dispersion containing a desired particulate binder (binder for negative electrode mixture layer). It was.

<Manufacture of slurry composition for negative electrode>
100 parts of artificial graphite (volume average particle size: 15.6 μm) as a negative electrode active material and 1 part of a 2% aqueous solution of carboxymethylcellulose sodium salt (“MAC350HC” manufactured by Nippon Paper Industries Co., Ltd.) as a thickener are mixed in an amount equivalent to solids Further, ion exchange water was added to adjust the solid content concentration to 68%, and the mixture was mixed at 25 ° C. for 60 minutes. Ion exchange water was added to the liquid mixture thus obtained to adjust the solid content concentration to 62%, and the mixture was further mixed at 25 ° C. for 15 minutes. To this mixed solution, 1.5 parts of the above aqueous dispersion containing the particulate binder is added in an amount corresponding to the solid content, and ion-exchanged water is further added to adjust the final solid content concentration to 52%, and further for 10 minutes. Mixed. This was defoamed under reduced pressure to obtain a negative electrode slurry composition having good fluidity.

<Manufacture of negative electrode>
The slurry composition for negative electrode was applied on a copper foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying was about 150 μm and dried. This drying was performed by conveying the copper foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Thereafter, heat treatment was performed at 120 ° C. for 2 minutes to obtain a negative electrode raw material before pressing. The negative electrode raw material before pressing was rolled with a roll press to obtain a negative electrode after pressing with a negative electrode mixture layer thickness of 80 μm.

<Production of positive electrode slurry composition>
100 parts of LiCoO ₂ having a volume average particle diameter of 12 μm as the positive electrode active material, ₂ parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., product name “HS-100”) as the conductive material, and binder for positive electrode (positive electrode mixture layer) Polyvinylidene fluoride (manufactured by Kureha Co., Ltd., product name “# 7208”) as a solid content was mixed in an amount of 2 parts, and N-methylpyrrolidone was added thereto to make the total solid content concentration 70%. These were mixed by a planetary mixer to obtain a positive electrode slurry composition.

<Production of positive electrode>
The positive electrode slurry composition was applied onto a 20 μm-thick aluminum foil as a current collector by a comma coater so that the film thickness after drying was about 150 μm and dried. This drying was performed by conveying the aluminum foil in an oven at 60 ° C. at a speed of 0.5 m / min for 2 minutes. Thereafter, heat treatment was performed at 120 ° C. for 2 minutes to obtain a positive electrode raw material before pressing. The positive electrode raw material before pressing was rolled with a roll press to obtain a positive electrode.

<Manufacture of laminate of negative electrode or positive electrode and separator>
The positive electrode after pressing was cut into a circle having a diameter of 13 mm to obtain a circular positive electrode. Further, the negative electrode after pressing was cut out into a circle having a diameter of 14 mm to obtain a circular negative electrode. Further, the separator was cut into a circle having a diameter of 18 mm to obtain a circular separator.

  Then, only the negative electrode or the positive electrode was placed on one side of the circular separator so as to be in contact with the separator on the surface on the electrode mixture layer side. Thereafter, a heat press treatment was performed at a temperature of 80 ° C. and a pressure of 0.5 MPa for 10 seconds, and the positive electrode or the negative electrode was pressure-bonded to the separator to obtain a laminate including the positive electrode and the separator, and a laminate including the negative electrode and the separator. . Using these laminates, the adhesion between the separator and the electrode after immersion in the electrolytic solution was evaluated by the method described above. The results are shown in Table 1.

<Manufacture of lithium ion secondary batteries>
The pressed positive electrode was cut out to 49 cm × 5 cm. A separator cut out to 55 cm × 5.5 cm was disposed on the positive electrode mixture layer of the cut out positive electrode. Furthermore, the negative electrode after pressing was cut into 50 cm × 5.2 cm, and the cut negative electrode was arranged on the side opposite to the positive electrode of the separator so that the surface on the negative electrode mixture layer side faced the separator. This was wound by a winding machine to obtain a wound body. The wound body was pressed at 60 ° C. and 0.5 MPa to obtain a flat body. This flat body is wrapped with an aluminum packaging exterior as a battery exterior, and an electrolytic solution (solvent: ethylene carbonate (EC) / diethyl carbonate (DEC) / vinylene carbonate (VC) = 68.5 / 30 / 1.5 ( Volume ratio), electrolyte: LiPF ₆ ) having a concentration of 1M was injected so that no air remained. Further, in order to seal the opening of the aluminum packaging material, heat sealing at 150 ° C. was performed to close the aluminum exterior. Thus, an 800 mAh wound type lithium ion secondary battery was manufactured.
About the lithium ion secondary battery obtained in this way, the high temperature cycling characteristic and the low temperature output characteristic were evaluated by the method mentioned above. The results are shown in Table 1.

(Examples 2 to 4)
In the same manner as in Example 1 except that the amounts of methyl methacrylate, methacrylic acid, and ethylene glycol dimethacrylate were changed as shown in Table 1 during the preparation of the particulate polymer, the particulate polymer, non-aqueous secondary A battery functional layer composition, a separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
When preparing the particulate polymer, the monomer composition used for the production of the core part was changed to 43 parts methyl methacrylate and 1 part methacrylic acid, respectively, and (meth) acrylic acid ester Except for adding 35 parts of butyl acrylate as a monomer, in the same manner as in Example 1, a particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode, a positive electrode, A laminate and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
When preparing the particulate polymer, the amount of styrene was changed to 18 parts for the monomer composition used for the production of the shell part, and 1 part of acrylonitrile as a (meth) acrylonitrile monomer and a crosslinkable monomer. In the same manner as in Example 1 except that 1 part of ethylene glycol dimethacrylate was added and methacrylic acid was not added, a particulate polymer, a composition for a non-aqueous secondary battery functional layer, and a functional layer were prepared. The provided separator, negative electrode, positive electrode, laminate, and lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
When preparing the particulate polymer, the amount of styrene was changed to 15 parts for the monomer composition used for the production of the shell part, and 4.5 parts of acrylonitrile as a (meth) acrylonitrile monomer was newly cross-linked. A composition for a particulate polymer and a non-aqueous secondary battery functional layer in the same manner as in Example 1 except that 0.5 part of ethylene glycol dimethacrylate as a monomer was added and methacrylic acid was not added. A separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
The same procedure as in Example 1 was conducted except that the amount of L-aspartic acid was changed to 2.8 parts with respect to 100 parts of the particulate polymer having a core-shell structure when preparing the composition for a non-aqueous secondary battery functional layer. Thus, a particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

Example 9
Except for changing the amount of L-aspartic acid to 5 parts with respect to 100 parts of the particulate polymer having a core-shell structure when preparing the composition for a nonaqueous secondary battery functional layer, the same as in Example 1, A particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 10)
The same procedure as in Example 1 was conducted except that the amount of L-aspartic acid was changed to 0.6 parts with respect to 100 parts of the particulate polymer having a core-shell structure at the time of preparing the composition for a non-aqueous secondary battery functional layer. Thus, a particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 11)
Example 1 except that 1 part of L-glutamic acid was added to 100 parts of the particulate polymer having a core-shell structure instead of L-aspartic acid when preparing the composition for a non-aqueous secondary battery functional layer. Similarly, a particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 12)
In the same manner as in Example 1, a particulate polymer having a core-shell structure, a functional layer binder, and a composition for a functional layer of a non-aqueous secondary battery containing the particulate polymer and the functional layer binder. Was prepared. And, at the time of manufacturing the lithium ion secondary battery, the separator base material is used as it is as a separator without forming a functional layer, and as a negative electrode and a positive electrode, a negative electrode including a functional layer and a positive electrode including a functional layer are used. A lithium ion secondary battery was produced in the same manner as in Example 1. Moreover, the laminated body of the negative electrode provided with a functional layer or the positive electrode provided with a functional layer, and the separator which consists of a separator base material was manufactured similarly to Example 1. FIG. Various evaluations were performed in the same manner as in Example 1. The results are shown in Table 1. In addition, the preparation methods of the negative electrode provided with the said functional layer and the positive electrode provided with a functional layer are as follows.

<Preparation of negative electrode with functional layer>
In the same manner as in Example 1, after forming a negative electrode mixture layer having a thickness of 80 μm on the current collector (copper foil) to obtain an electrode substrate (negative electrode substrate), on the surface on the negative electrode mixture layer side, The functional layer composition was applied by spray coating and dried at 50 ° C. for 1 minute. Thus, a negative electrode having a functional layer having a thickness of 1 μm on one side was produced.

<Preparation of positive electrode with functional layer>
In the same manner as in Example 1, after forming a positive electrode mixture layer having a thickness of 80 μm on a current collector (aluminum foil) to obtain an electrode substrate (positive electrode substrate), on the surface on the positive electrode mixture layer side, The functional layer composition was applied by spray coating and dried at 50 ° C. for 1 minute. Thus, a positive electrode having a functional layer having a thickness of 1 μm on one side was produced.

(Comparative Example 1)
Except for changing the amount of L-aspartic acid to 7 parts with respect to 100 parts of the particulate polymer having a core-shell structure when preparing the composition for a non-aqueous secondary battery functional layer, the same as in Example 1, A particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
The same procedure as in Example 1 was conducted except that the amount of L-aspartic acid was changed to 0.05 parts with respect to 100 parts of the particulate polymer having a core-shell structure at the time of preparing the composition for a nonaqueous secondary battery functional layer. Thus, a particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode, a positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
At the time of preparing the particulate polymer, the monomer composition used for the production of the core part was prepared by adding 93.75 parts of methyl methacrylate, 5.0 parts of methacrylic acid, and 1. A particulate polymer not having a core-shell structure, a composition for a non-aqueous secondary battery functional layer, and a functional layer were obtained in the same manner as in Example 1 except that each part was changed to 25 parts and the shell part was not formed. The provided separator, negative electrode, positive electrode, laminate, and lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
When preparing the particulate polymer, the monomer composition used for the production of the shell part was changed to 10 parts of styrene and 0.4 parts of methacrylic acid, respectively. Except for adding 9.6 parts of methyl methacrylate as an ester monomer, the same procedure as in Example 1 was carried out, a particulate polymer, a composition for a non-aqueous secondary battery functional layer, a separator provided with a functional layer, a negative electrode A positive electrode, a laminate, and a lithium ion secondary battery were produced. Various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

In the table below,
“MMA” indicates methyl methacrylate;
“BA” indicates butyl acrylate,
“MAA” indicates methacrylic acid,
“EDMA” refers to ethylene glycol dimethacrylate,
“ST” indicates styrene,
“AN” indicates acrylonitrile,
“NMA” indicates N-methylolacrylamide,
“AAm” indicates acrylamide,
“L-Asp” refers to L-aspartic acid;
“L-Glu” refers to L-glutamic acid.

From Table 1, in Examples 1-12 using the composition containing the particulate polymer which has a predetermined | prescribed core-shell structure and property, and a predetermined amount of amino acid, dispersion | distribution of the composition for non-aqueous secondary battery functional layers It can be seen that it is possible to obtain a secondary battery having high battery properties, excellent adhesion between the separator and the electrode after immersion in an electrolyte, and excellent battery characteristics such as high-temperature cycle characteristics and low-temperature output characteristics.
Further, from Table 1, in Comparative Example 1 in which the content of amino acids in the composition for a non-aqueous secondary battery functional layer is more than 5 parts with respect to 100 parts of the particulate polymer having a core-shell structure, the non-aqueous secondary battery It can be seen that although the dispersibility of the battery functional layer composition and the adhesion between the separator and the electrode after immersion in the electrolyte can be improved, a secondary battery excellent in high-temperature cycle characteristics cannot be obtained.
Furthermore, from Table 1, in Comparative Example 2 in which the content of amino acid in the composition for a non-aqueous secondary battery functional layer is less than 0.1 part with respect to 100 parts of the particulate polymer having a core-shell structure, It turns out that the dispersibility of the composition for secondary battery functional layers is bad, the adhesiveness of the electrode and separator after immersion in electrolyte solution is low, and a secondary battery excellent in high temperature cycle characteristics cannot be obtained.
Further, from Table 1, in Comparative Example 3 where the electrolyte swelling degree of the core part of the particulate polymer is more than 30 times, the adhesion between the electrode and the separator after immersion in the electrolyte is low, and the high temperature cycle characteristics are excellent. It turns out that a secondary battery cannot be obtained.
Furthermore, from Table 1, in Comparative Example 4 in which the electrolyte solution swelling degree of the shell portion of the particulate polymer is more than 4 times, the adhesion between the electrode after immersion in the electrolyte and the separator is low, and the high temperature cycle characteristics are excellent. It turns out that a secondary battery cannot be obtained.

According to the present invention, a non-aqueous secondary battery capable of forming a functional layer for a non-aqueous secondary battery that exhibits excellent adhesion even after being immersed in an electrolytic solution and can provide excellent battery characteristics to the secondary battery. A composition for a secondary battery functional layer can be provided.
In addition, according to the present invention, it is possible to provide a functional layer for a non-aqueous secondary battery that exhibits excellent adhesion even after being immersed in an electrolytic solution and can provide excellent battery characteristics for a secondary battery. it can.
Furthermore, according to this invention, the non-aqueous secondary battery which is excellent in battery characteristics, such as a high temperature cycling characteristic, can be provided.

DESCRIPTION OF SYMBOLS 100 Particulate polymer 110 Core part 110S Outer surface of core part 120 Shell part

Claims (5)

A composition for a non-aqueous secondary battery functional layer containing a particulate polymer and an amino acid,
The proportion of the amino acid is 0.1 to 5 parts by mass with respect to 100 parts by mass of the particulate polymer,
The particulate polymer has a core-shell structure including a core portion and a shell portion that partially covers an outer surface of the core portion,
The core portion is made of a polymer having an electrolyte solution swelling degree of 5 times or more and 30 times or less,
The shell part is a composition for a non-aqueous secondary battery functional layer made of a polymer having an electrolyte solution swelling degree of more than 1 time and 4 times or less. The glass transition temperature of the polymer constituting the core part is −50 ° C. or higher and 150 ° C. or lower,
The composition for a non-aqueous secondary battery functional layer according to claim 1, wherein a glass transition temperature of the polymer constituting the shell portion is 50 ° C or higher and 200 ° C or lower.   The composition for a non-aqueous secondary battery functional layer according to claim 1 or 2, wherein the amino acid contains at least one of aspartic acid and glutamic acid.   The functional layer for non-aqueous secondary batteries formed using the composition for non-aqueous secondary battery functional layers as described in any one of Claims 1-3.   A non-aqueous secondary battery comprising the functional layer for a non-aqueous secondary battery according to claim 4.

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