JP2014130792A - Method for manufacturing electrode for power storage device, and electrode and power storage device obtained thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrode for a power storage device capable of selecting a dopant anion suitable for the electrode and capable of obtaining a new power storage device having sufficient battery performance, and an electrode and a power storage device obtained thereby.SOLUTION: Provided is a method for manufacturing an electrode, at least one of a cathode 2 and an anode 4, of a power storage device having an electrolyte layer 3 and the cathode 2 and the anode 4 disposed facing each other across the electrolyte layer 3, the method for manufacturing the power storage device electrode comprising steps a to c, in which molecular sizes of (X) to (Z) are (X)<(Y)<(Z): a step a, in which low-molecular-weight anion (X) is dedoped from conductive polymer (W); a step b, in which an anionic material (Y) having a plurality of negative charges is doped with proton acid into the conductive polymer (W) obtained by the step a; a step c, in which an electrode is formed using at least the conductive polymer (W) obtained by the step b and a polymer anion (Z).

Description

  The present invention relates to a method for producing an electrode for an electricity storage device, an electrode obtained thereby, and an electricity storage device, and more specifically, an electricity storage device capable of selecting a dopant anion suitable for the electrode and obtaining a novel electricity storage device having sufficient battery performance. The present invention relates to a method for manufacturing a device electrode, an electrode obtained thereby, and an electricity storage device.

  In recent years, with the advancement and development of electronic technology in portable PCs, mobile phones, personal digital assistants (PDAs), secondary batteries that can be repeatedly charged and discharged are widely used as power storage devices for these electronic devices. Yes. In such an electrochemical storage device such as a secondary battery, it is desired to increase the capacity of a material used as an electrode.

  The electrode of the electricity storage device contains an active material having a function capable of inserting and removing ions. The insertion / desorption of ions in the active material is also called so-called doping / dedoping (or sometimes referred to as doping / dedoping), and the doping / dedoping amount per certain molecular structure is called the doping rate. The higher the material, the higher the capacity of the battery.

  Electrochemically, it is possible to increase the capacity of the battery by using a material having a large amount of ion insertion / extraction as an electrode. More specifically, lithium secondary batteries, which are attracting attention as power storage devices, use a graphite-based negative electrode that can insert and desorb lithium ions, and about one lithium ion is inserted per six carbon atoms. -Desorption and high capacity have been achieved.

  Among such lithium secondary batteries, a lithium-containing transition metal oxide such as lithium manganate or lithium cobaltate is used for the positive electrode, and a carbon material capable of inserting and removing lithium ions is used for the negative electrode. Lithium secondary batteries that face each other in an electrolytic solution have a high energy density, and thus are widely used as power storage devices for the electronic devices described above.

  However, the lithium secondary battery is a secondary battery that obtains electric energy by an electrochemical reaction, and has a drawback that the output density is low because the speed of the electrochemical reaction is low. Furthermore, since the internal resistance of the secondary battery is high, rapid discharge is difficult and rapid charge is also difficult. Moreover, since an electrode and electrolyte solution deteriorate by the electrochemical reaction accompanying charging / discharging, generally a lifetime, ie, a cycling characteristic, is not good.

  Therefore, in order to improve the above problem, a lithium secondary battery using a conductive polymer such as polyaniline having a dopant anion as a positive electrode active material is also known (see Patent Document 1).

  However, in general, a secondary battery having a conductive polymer as a positive electrode active material is an anion transfer type in which an anion is doped into the conductive polymer during charging and the anion is dedoped from the polymer during discharging. Therefore, when a carbon material that can insert and desorb lithium ions is used as the negative electrode active material, a cation-moving rocking chair type secondary battery in which cations move between both electrodes during charge and discharge cannot be configured. . The rocking chair type secondary battery has the advantage that the amount of the electrolyte is small, but the secondary battery having the conductive polymer as the positive electrode active material cannot do so, and contributes to the miniaturization of the electricity storage device. Can not.

  In order to solve such problems, a large amount of electrolytic solution is not required, and the ion concentration in the electrolytic solution is not substantially changed, thereby improving the capacity density per volume, weight, and energy density. A cation migration type secondary battery has also been proposed. In this method, a positive electrode is formed using a conductive polymer having a polymer anion such as polyvinyl sulfonic acid as a dopant, and lithium metal is used for the negative electrode (see Patent Document 2).

Japanese Patent Laid-Open No. 3-129679 Japanese Patent Laid-Open No. 1-132052

  However, the secondary battery is not yet sufficient in performance. That is, the capacity density and energy density are lower than those of a lithium secondary battery using a lithium-containing transition metal oxide such as lithium manganate or lithium cobaltate for the positive electrode.

  On the other hand, when a conductive polymer is used for the positive electrode and a polyvalent dopant such as a polymer anion is used as a dopant, a rocking chair type battery is obtained, and the capacity can be increased by reducing the amount of the electrolyte.

  However, the dopant of the conductive polymer is generally a low-molecular anion incorporated during polymerization, and this low-molecular anion becomes an anion transfer type that is dedoped from the polymer. Mold battery cannot be formed.

  The present invention has been made in order to solve the above-described problems in power storage devices such as conventional lithium secondary batteries and electric double layer capacitors, and an electrode can be easily doped with an anion that can be a rocking chair type dopant. And it aims at providing the method of manufacturing the electrode for electrical storage devices which can obtain the novel electrical storage device which has sufficient battery performance, the electrode obtained by it, and an electrical storage device.

In order to achieve the above object, the present invention provides a method for producing at least one of the positive electrode and the negative electrode of an electricity storage device having an electrolyte layer and a positive electrode and a negative electrode provided to face each other. The manufacturing method of the electrode for electrical storage devices which is provided with the process of ac and the molecular size of following (X)-(Z) is (X) <(Y) <(Z) is made into a 1st summary.
a. A step of dedoping the low molecular anion (X) from the conductive polymer (W).
b. A step of proton acid doping a plurality of negatively charged anionic materials (Y) to the conductive polymer (W) obtained by the step a.
c. A step of forming an electrode using at least the conductive polymer (W) obtained by the step b and the polymer anion (Z).

  Moreover, this invention makes the 2nd summary the electrode for electrical storage devices obtained by the manufacturing method of the said electrode for electrical storage devices.

  Moreover, this invention makes the electrical storage device using the said electrode 3rd summary.

  That is, the present inventors have made extensive studies in order to obtain a novel power storage device that can be manufactured without complicated operations and has a high capacity density and a high energy density. In the process, we focused on the rocking chair type power storage device mechanism, which is a cation transfer type that requires a small amount of electrolyte solution. As a result, the present inventors can select a dopant anion suitable for a rocking chair type electrode, can easily and quickly produce a novel electricity storage device having sufficient battery performance, and provide an electricity storage device having sufficient battery characteristics. The inventors have found a method for manufacturing an electricity storage device that can be obtained and have reached the present invention.

  Thus, the present invention is a method for producing at least one of the positive electrode and the negative electrode of an electricity storage device having an electrolyte layer and a positive electrode and a negative electrode provided to face each other with the electrolyte layer interposed therebetween. It is possible to select a dopant anion suitable for the electrode and to prepare a process for producing an electrode for an electricity storage device in which the molecular size of (X) to (Z) is (X) <(Y) <(Z) It is possible to obtain an electricity storage device having excellent battery performance.

  Further, when the polymer anion (Z) serves as a binder for the electrode, it is not necessary to add another binder as an electrode forming material, so that an electricity storage device with a higher capacity density can be obtained.

It is sectional drawing which shows typically the structure of the electrical storage device produced using the electrode obtained by the manufacturing method of the electrode for electrical storage devices of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. However, the description described below is an example of embodiments of the present invention, and the present invention is not limited to the following contents.

As described above, the method for producing an electrode for an electricity storage device of the present invention includes at least one of the positive electrode and the negative electrode of an electricity storage device having an electrolyte layer and a positive electrode and a negative electrode provided to face each other. This is a method for producing an electrode for an electricity storage device comprising the following steps a to c and the molecular sizes of the following (X) to (Z) being (X) <(Y) <(Z).
a. A step of dedoping the low molecular anion (X) from the conductive polymer (W).
b. A step of proton acid doping a plurality of negatively charged anionic materials (Y) to the conductive polymer (W) obtained by the step a.
c. A step of forming an electrode using at least the conductive polymer (W) obtained by the step b and the polymer anion (Z).

  That is, the present invention provides a low molecular anion (X) that is dedoped from the conductive polymer (W), and a plurality of negatively charged anionic materials (Y) are protonated instead of the low molecular anion. In this method, the dopant anion is replaced, and the electrode is formed using the conductive polymer and the polymer anion (Z) in which the dopant anion is replaced.

  Prior to the description of the electrode manufacturing method according to the present invention, the materials (W), (X), (Y), and (Z) used when forming the electrode will be described first.

<About conductive polymer (W)>
The conductive polymer (W) used as the electrode forming material is an ionic species inserted into the polymer in order to compensate for a change in charge generated or lost by an oxidation reaction or a reduction reaction of the polymer main chain, or A group of polymers in which the conductivity of the polymer itself is changed by detachment from the polymer.

  In such a polymer, a state with high conductivity is referred to as a doped state, and a state with low conductivity is referred to as a dedope state. Even if a polymer having conductivity loses conductivity by an oxidation reaction or a reduction reaction and becomes insulative (that is, in a dedoped state), such a polymer is reversibly conductive again by the oxidation-reduction reaction. Therefore, the insulating polymer in such a dedope state is also included in the category of the conductive polymer in the present invention.

  The conductive polymer can also be referred to as a polymer whose conductivity is changed by ion insertion / extraction, for example, polyacetylene, polypyrrole, polyaniline, polythiophene, polyfuran, polyselenophene, polyisothianaphthene, polyphenylene sulfide, polyphenylene oxide, Examples thereof include polyazulene, poly (3,4-ethylenedioxythiophene), and various derivatives thereof. In particular, polyaniline or polyaniline derivatives having a large electrochemical capacity are preferably used.

  Examples of the polyaniline derivative include at least a substituent such as an alkyl group, an alkenyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylaryl group, an arylalkyl group, and an alkoxyalkyl group at positions other than the 4-position of the aniline. One that has one. Among these, o-substituted anilines such as o-methylaniline, o-ethylaniline, o-phenylaniline, o-methoxyaniline, o-ethoxyaniline, m-methylaniline, m-ethylaniline, m-methoxyaniline, m -M-substituted anilines such as ethoxyaniline and m-phenylaniline are preferably used. These may be used alone or in combination of two or more.

  In the production method of the present invention, there is a step of dedoping the low molecular anion (X) from the conductive polymer (W). Next, the low molecular anion will be described.

<About low molecular anion (X)>
The low molecular anion (X) in the present invention refers to a low molecular anion incorporated during polymerization of a conductive polymer. For example, BF ₄ ⁻ , Cl ⁻ , SO ₄ ²⁻ , CH ₃ SO ₃ ⁻ , benzene Examples thereof include sulfonate anions, and among them, BF ₄ ⁻ , Cl ⁻ , and SO ₄ ²⁻ are common and preferable as dopant anions for conductive polymers.

  The molecular size of the low-molecular anion (X) is smaller than the plurality of negatively charged anionic materials (Y) and polymer anions (Z). Specifically, the molecular weight (weight) of the low molecular anion (X) is usually 30 to 300, preferably 30 to 200, and more preferably 30 to 100. In the present invention, the molecular size can be determined by the molecular weight as described above.

  Next, in the production method of the present invention, in the conductive polymer (W) dedoped with the low molecular anion (X), instead of the low molecular anion, a plurality of negatively charged anionic materials (Y) are converted into protonic acids. There is a step of doping. Hereinafter, the anionic material (Y) having a plurality of negative charges will be described.

<Multiple negatively charged anionic materials (Y)>
Examples of the plurality of negatively charged anionic materials (Y) include polymer anions and polyvalent anionic compounds. Low molecular weight materials are preferable as long as they are polymer anions. That is, the molecular size of the plurality of negatively charged anionic materials (Y) is medium in the components (X) to (Z) and is larger than the low molecular anion (X), and the polymer anion (Z ) Is smaller.

  Specifically, the molecular weight (weight) of a plurality of negatively charged anionic materials (Y) is usually 100 to 500,000, preferably 120 to 50,000, and more preferably 150 to 30. , 000. If the molecular weight is too large, doping tends to be difficult in the process of doping (Y) into (W) protonic acid. On the other hand, if the molecular weight is too small, when formed as a battery electrode, it does not act as a so-called fixed anion, so that it is difficult to form a rocking chair type battery. In addition, the molecular weight in the case of a polymer is a value when a weight average molecular weight is measured by gel permeation chromatography (GPC) with a polystyrene standard at room temperature (25 ° C.).

  As the plurality of negatively charged anionic materials (Y), compounds having at least one selected from the group consisting of a carboxyl group, an aromatic hydroxyl group, a sulfonic acid group, and a thiol group in the molecule are preferably used. It is done.

  Polycarboxylic acid is more preferably used as the compound having a carboxyl group. Examples of the polycarboxylic acid include polyacrylic acid, polymethacrylic acid, polyvinyl benzoic acid, polyallyl benzoic acid, polymethallyl benzoic acid, polymaleic acid, polyfumaric acid, polyglutamic acid, and polyaspartic acid. Polyacrylic acid.

  Examples of the compound having an aromatic hydroxyl group include polyfunctional phenol resins. Among them, phenolsulfonic acid novolak resins and hydroxybenzoic acid novolak resins are preferably used.

Further, the compound having a sulfonic acid group is classified into an aliphatic group and an aromatic group, and the aliphatic group has a structural formula represented by the general formula HOOC-R ¹ -SO ₃ H (wherein R ¹ Represents a divalent saturated aliphatic hydrocarbon group having 1 or 2 carbon atoms which may have a hydroxyl group), or a general formula (HOOC) ₂ —R ² —SO ₃ H (wherein R ² is An aliphatic monosulfonic acid, sulfoacetic acid, sulfolactic acid, sulfomalonic acid, sulfosuccinic acid represented by a trivalent saturated or unsaturated aliphatic hydrocarbon group having 1 or 2 carbon atoms which may have a hydroxyl group) , Sulfotartaric acid, sulfomalic acid, sulfomaleic acid or sulfofumaric acid, and the like. Among them, sulfosuccinic acid is more preferable. On the other hand, as the aromatic type, sulfosalicylic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, sulfobenzoic acid, 4-sulfo-2,3,5,6-tetrafluorobenzoic acid, 1,5-naphthalenedisulfonic acid Phthalic acid, isophthalic acid, terephthalic acid, hydroquinonesulfonic acid, dihydroxyanthracenesulfonic acid, and the like. Among these, sulfosalicylic acid is more preferable.

Examples of the compound having a thiol group include dithioethylene glycol represented by HSCH ₂ CH ₂ SH and 2,5-dimercapto-1,3,4-thiadiazole represented by C ₂ N ₂ S (SH) _2. (Hereinafter referred to as “DMcT”), s-triazine-2,4,6-trithiol represented by C ₃ H ₃ N ₃ S ₃ , 7-methyl- represented by C ₆ H ₆ N ₄ S ₃ Examples include 2,6,8-trimercaptopurine or 4,5-diamino-2,6-dimercaptopyrimidine represented by C ₄ H ₆ N ₄ S _2. Among them, DMcT is more preferable. .

  As described above, various compounds can be used as the plurality of negatively charged anionic materials (Y), and these can be used alone or in combination of two or more.

  Next, the present invention comprises a conductive polymer (W) in which the low molecular anion (X) and a plurality of negatively charged anionic materials (Y) are replaced as a dopant anion, and a polymer anion (Z). And forming an electrode. Therefore, the polymer anion (Z) will be described next.

<Polymer anion (Z)>
The polymer anion (Z) is a negatively charged polymer, an anion compound having a relatively large molecular weight, and has the largest molecular size among the components (X) to (Z). Here, the polymer anion (Z) is preferably one that can also serve as a binder.

  Specifically, the weight average molecular weight of the polymer anion (Z) is usually 10,000 to 5,000,000, preferably 20,000 to 2,000,000, and more preferably 30,000. ~ 1,000,000. If the weight average molecular weight is too large, it tends to be difficult to prepare a solution for electrode preparation. On the other hand, if the weight average molecular weight is too small, it does not operate as a so-called fixed anion when formed as a battery electrode. This is because it tends to be difficult to form a battery of a type.

  As the polymer anion (Z), polycarboxylic acid is preferably used. Examples of the polycarboxylic acid include polyacrylic acid, polymethacrylic acid, polyvinylbenzoic acid, polyallylbenzoic acid, polymethallylbenzoic acid, polymaleic acid, polyfumaric acid, polyglutamic acid, and polyaspartic acid. Polymethacrylic acid is particularly preferably used. These may be used alone or in combination of two or more.

  In the method for producing an electrode according to the present invention, when a polymer such as the above polycarboxylic acid is used, this polymer has a function as a binder and also functions as a dopant, and thus has a rocking chair type mechanism. Therefore, it is considered to be involved in the improvement of the characteristics of the electricity storage device according to the present invention.

  In the production method of the present invention, the anion of the polymer anion (Z) may be compensated with a counter ion. A polymer in which the carboxylic acid in the polymer is substituted with lithium to form a lithium type is preferably used. Such lithium substitution is preferably 40% or more of the carboxyl groups in the polymer, more preferably 100%.

  The polymer anion (Z) is usually in the range of 1 to 100 parts by weight, preferably 2 to 70 parts by weight, and most preferably 5 to 40 parts by weight with respect to 100 parts by weight of the conductive polymer (W). Used. If the amount of the polymer anion (Z) relative to the W component is too small, it tends to be difficult to obtain an electricity storage device excellent in energy density. On the other hand, if the amount of the polymer anion (Z) relative to the W component is too large, This is because it is difficult to obtain a high power storage device.

  Furthermore, as an electrode forming material, a conductive auxiliary, a binder other than the polymer anion (Z), and the like can be appropriately blended with the conductive polymer (W) and the polymer anion (Z) as necessary.

  The conductive auxiliary agent may be any conductive material whose properties do not change depending on the potential applied during the discharge of the electricity storage device, and examples thereof include conductive carbon materials and metal materials, among which acetylene black and ketjen black A conductive carbon black such as carbon fiber, or a fibrous carbon material such as carbon fiber or carbon nanotube is preferably used. Particularly preferred is conductive carbon black.

  Examples of the binder other than the polymer anion (Z) include vinylidene fluoride.

<About manufacturing method of electrode for power storage device>
The manufacturing method of the electrode for electrical storage devices of this invention is demonstrated using the said electrode formation material.

As mentioned above, according to the manufacturing method of the electrode for electrical storage devices of this invention, an electrode is formed through the process of following ac. Hereinafter, steps a to c will be described in order.
a. A step of dedoping the low molecular anion (X) from the conductive polymer (W).
b. A step of proton acid doping a plurality of negatively charged anionic materials (Y) to the conductive polymer (W) obtained by the step a.
c. A step of forming an electrode using at least the conductive polymer (W) obtained by the step b and the polymer anion (Z).

(About step a)
First, the step a includes a step of dedoping the low molecular anion (X) from the conductive polymer (W) to bring the conductive polymer (W) into a dedope state. It is obtained by neutralizing the dopant that the polymer (W) has. For example, the conductive polymer (W) in a dedope state is obtained by stirring in a solution that neutralizes the dopant of the conductive polymer (W) and then washing and filtering. Specifically, in order to dedope polyaniline having tetrafluoroboric acid (BF ₄ ⁻ ) as a dopant, a method of neutralizing by stirring in an aqueous sodium hydroxide solution can be mentioned.

Further, as another method of the step a, the conductive polymer (W) can be reduced, and the low molecular anion (X) can be dedoped to bring the conductive polymer (W) into a dedope state. . For example, the conductive polymer (W) in a dedope state is obtained by stirring the conductive polymer (W) in a reducing agent solution and then washing and filtering. Specifically, in order to dedope polythiophene using hydrochloric acid (Cl ⁻ ) as a dopant, a method of stirring in a hydrazine solution can be mentioned.

  Further, as another method of the above step a, the powder obtained by neutralizing with the above sodium hydroxide is filtered and washed, and then treated in a reducing agent solution such as hydrazine as described above. A method for bringing the polymer (W) into a dedope state can be mentioned.

(About step b)
Next, in the step b, the plurality of negatively charged anionic materials (Y) are substantially used as protonic acids, and the Y component is protonated into the undoped conductive polymer (W). In the acid doping step, for example, there is a method of proton acid doping by dispersing a dedope state conductive polymer (W) in an acidic aqueous solution of a plurality of negatively charged anionic materials (Y). can give.

  The temperature of the aqueous solution during the proton acid doping is preferably 40 to 100 ° C, more preferably 50 to 95 ° C, and particularly preferably 55 to 85 ° C. This is because if the temperature of the aqueous solution is too low, protonic acid doping tends to be difficult to proceed, whereas if the temperature of the aqueous solution is too high, the conductive polymer (W) tends to deteriorate.

(About step c)
Further, the step c is a step of forming an electrode using at least the conductive polymer (W) in the doped state and the polymer anion (Z). For example, the polymer anion (Z) is converted into water. A conductive polymer (W) doped with protonic acid in the above step b and, if necessary, a conductive aid, a binder and the like are added thereto and sufficiently dispersed therein to prepare a paste. After this is applied on the current collector, water is evaporated, so that the W component, the Y component, and the Z component on the current collector (and optional components such as a conductive auxiliary agent and a binder as necessary) The sheet electrode can be obtained as a composite of the above mixture.

  Here, the relationship between the molecular size of the low molecular anion (X) incorporated during the polymerization of the conductive polymer (W), a plurality of negatively charged anionic materials (Y), and polymer anions (Z) As described above, (X) <(Y) <(Z). This is because if the molecular size of the X component is large, the conductive polymer (X) taken in during polymerization is difficult to remove by the dedoping treatment. On the other hand, if the molecular size of the Y component is too large, the progress of the proton acid doping becomes slow and impractical, and if it is too small, a rocking chair type battery tends not to be formed when the battery device is formed. Further, the Z component preferably serves as a binder and has a high molecular weight in order to serve as a fixed anion for forming a rocking chair type battery when forming a battery device.

<About electrodes for power storage devices>
The electrode for an electricity storage device obtained by the above production method is a composite comprising at least a conductive polymer (W) doped with the Y component and a polymer anion (Z), and the thickness of such an electrode is 1-1000 μm. It is preferable that the thickness is 10 to 500 μm. In other words, if the thickness is too thin, there is a tendency to become an electricity storage device in which sufficient capacity cannot be obtained. Conversely, if the thickness is too thick, it becomes difficult for ions to diffuse inside the electrode and a desired output cannot be obtained. This is because there is a tendency.

  The thickness of the electrode is obtained by measuring the electrode using a dial gauge (made by Ozaki Mfg. Co., Ltd.) whose tip shape is a flat plate having a diameter of 5 mm, and obtaining the average of 10 measured values with respect to the surface of the electrode. . When an electrode (porous layer) is provided on the current collector and these are integrated into a composite, the thickness of the composite is measured in the same manner as described above, and the average value of the 10 points is calculated. After the determination, the value can be determined by subtracting the thickness of the current collector.

  The electrode is preferably formed in the form of a porous sheet, and the porosity thereof is preferably 50 to 80%, more preferably 60 to 70%.

  The porosity (%) of the electrode can be calculated by {(apparent volume of electrode−true volume of electrode) / apparent volume of electrode} × 100.

  Here, the apparent volume of the electrode means “electrode area of the electrode × electrode thickness”. Specifically, the volume of the electrode material, the volume of the void in the electrode, and the space of the uneven portion on the electrode surface Consists of total volume. In addition, the true volume of the electrode refers to the “volume of the electrode constituent material”. Specifically, using the constituent weight ratio of the positive electrode constituent material and the true density value of each constituent material, The average density is calculated, and it is obtained by dividing the total weight of the electrode constituent materials by this average density.

  The true density (true specific gravity) of each constituent material used above was calculated with polyaniline 1.2 (including dopant), polyacrylic acid 1.2, and Denka black (acetylene black) 2.0.

  In the electrode formed as described above, since the polymer anion (Z) is arranged as a mixture with the conductive polymer (W), a plurality of negatively charged anionic materials (Y) are used as the conductive material. Since the conductive polymer (W) is incorporated as a dopant anion of the conductive polymer (W), the Z component and the Y component are fixed in the composite body, that is, in the electrode. And the Z component and Y component which are the dopant anions fixedly arranged in the vicinity of the W component in this way are used for charge compensation at the time of oxidation-reduction of the conductive polymer (W).

  The details of why it becomes a high-capacity electricity storage device are unclear, but the polymer anion (Z) has a Z component fixedly disposed in the vicinity of the conductive polymer (W), so that a pair of cations such as lithium ions can be obtained. By becoming a fixed ion and becoming suitable for a cation transfer type rocking chair type electricity storage device, and further replacing the dopant of the conductive polymer (W) with a dopant anion suitable for a rocking chair type, etc. It is assumed that the active material can be used more efficiently as described above.

  Thus, according to the production method of the present invention, it is considered that it contributes to rocking chair type ion migration and prevents a decrease in capacity even when the entire electrolyte weight is reduced.

  In addition, although the electrode which concerns on this invention can be used for both the positive electrode and negative electrode of an electrical storage device, it is preferable to use as a positive electrode especially. That is, as shown in FIG. 1, the electrode according to the present invention includes any one of a positive electrode 2 and a negative electrode 4 in an electricity storage device provided with an electrolyte layer 3 and a pair of electrodes (positive electrode 2 and negative electrode 4) facing each other. However, it is preferable to use as the positive electrode 2. Hereinafter, the structure of an electrical storage device is demonstrated about the case where the electrode which concerns on the electrical storage device of this invention is used as the positive electrode 2. FIG.

<About the electrolyte layer>
Next, the electrolyte layer 3 is made of an electrolyte, and in particular, a sheet formed by impregnating a separator with an electrolytic solution or a sheet made of a solid electrolyte is preferably used. In addition, the sheet | seat which consists of solid electrolyte itself serves as the separator itself.

The electrolyte is composed of a solute and, if necessary, a solvent and various additives. Examples of the solute include at least one cation such as proton, alkali metal ion, quaternary ammonium ion, quaternary phosphonium ion, sulfonate ion, perchlorate ion, tetrafluoroborate ion, hexafluoro A combination of phosphate ions, hexafluoroarsenic ions, bis (trifluoromethanesulfonyl) imide ions, bis (pentafluoroethanesulfonyl) imide ions, halogen ions, phosphate ions, sulfate ions, nitrate ions, etc. Preferably used. Specific examples of such solutes include LiCF ₃ SO ₃ , LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiCl, etc. Can give.

  Moreover, as a solvent used as needed, at least one non-aqueous solvent such as carbonates, nitriles, amides, ethers, that is, an organic solvent is used. Specific examples of such an organic solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, acetonitrile, propionitrile, N, N'-dimethylacetamide, N-methyl-2- Examples include pyrrolidone, dimethoxyethane, diethoxyethane, and γ-butyrolactone. These may be used alone or in combination of two or more. In addition, what melt | dissolved the said solute in the said solvent may be called "electrolyte solution."

<About the counter electrode>
When the electrode obtained by the production method of the present invention is used as a positive electrode, the negative electrode is formed using a negative electrode active material capable of inserting / extracting ions. As the negative electrode active material, a carbon material, transition metal oxide, silicon, tin, or the like from which lithium ions can be inserted / extracted during oxidation / reduction is preferably used. Here, “use” means not only the case where only the forming material is used, but also the case where the forming material is used in combination with another forming material. Usually, the use ratio of the other forming material is , Set to less than 50% by weight of the forming material.

  Further, the electricity storage device uses a separator in addition to the positive electrode, the electrolyte layer, and the counter electrode. Such a separator can be used in various modes. As the separator, an insulating porous sheet that can prevent an electrical short circuit between the positive electrode and the negative electrode, is electrochemically stable, has a large ion permeability, and has a certain mechanical strength. Preferably, for example, a porous sheet made of a resin such as paper, non-woven fabric, polypropylene, polyethylene, or polyimide is preferably used. These may be used alone or in combination of two or more. Moreover, as above-mentioned, when the electrolyte layer 3 is a sheet | seat which consists of solid electrolytes, since it itself serves as a separator, it is not necessary to prepare another separator separately.

<About electricity storage devices>
According to the method for producing an electricity storage device of the present invention, a dopant anion suitable for an electrode can be selected, and a high-performance electricity storage device excellent in capacity density per active material weight and capacity density per electrode volume can be easily produced.

  As the charge / discharge mechanism of the electricity storage device of the present invention, the polymer anion (Z) is used as a binder as described above, but this binder itself functions as a dopant, and there is a part of a rocking chair type mechanism. It is assumed. Furthermore, the anionic material (Y) having a plurality of negative charges also functions as a fixed dopant and contributes to a rocking chair type mechanism. Therefore, it is assumed that there is a rocking chair type mechanism in which cations such as lithium ions move from the negative electrode to the positive electrode during discharging, and cations move from the positive electrode to the negative electrode during charging.

  Furthermore, since the electrode of the electricity storage device of the present invention is used in combination with the conductive polymer (W) and the polymer anion (Z), it has excellent charge / discharge characteristics like an electric double layer capacitor, and has a conventional electric property. The capacitance density is higher than that of the double layer capacitor. From this, it can be said that the electrical storage device according to the present invention is a capacitor-like secondary battery.

  Next, examples will be described. However, the present invention is not limited to these examples.

[Example 1]
First, prior to the production of an electrode for an electricity storage device, the following components were prepared and prepared.

[Preparation of conductive polymer (W)]
As the conductive polymer (W), a conductive polyaniline powder using tetrafluoroboric acid as a dopant was prepared as follows.

  To a 300 mL glass beaker containing 138 g of ion-exchanged water, 84.0 g (0.402 mol) of a 42 wt% concentration tetrafluoroboric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd., reagent grade) is added to a magnetic stirrer. While stirring, 10.0 g (0.107 mol) of aniline was added thereto. When aniline was added to the tetrafluoroboric acid aqueous solution, the aniline was dispersed as oily droplets in the tetrafluoroboric acid aqueous solution, but then dissolved in water within a few minutes, and the uniform and transparent aniline aqueous solution. Became. The aniline aqueous solution thus obtained was cooled to −4 ° C. or lower using a low temperature thermostat.

  Next, 11.63 g (0.134 mol) of manganese dioxide powder (manufactured by Wako Pure Chemical Industries, Ltd., reagent grade 1) as an oxidizing agent is added little by little to the aniline aqueous solution, and the temperature of the mixture in the beaker is -1. The temperature was not exceeded. Thus, by adding an oxidizing agent to the aniline aqueous solution, the aniline aqueous solution immediately turned black-green. Thereafter, when stirring was continued for a while, a black-green solid started to be formed.

Thus, after adding an oxidizing agent over 80 minutes, it stirred for further 100 minutes, cooling the reaction mixture containing the produced | generated reaction product. Then, using a Buchner funnel and a suction bottle, the obtained solid was No. The powder was obtained by suction filtration with 2 filter papers. This powder was stirred and washed in a 2 mol / L tetrafluoroboric acid aqueous solution using a magnetic stirrer. Subsequently, it was stirred and washed several times with acetone, and this was filtered under reduced pressure. The obtained powder was vacuum-dried at room temperature (25 ° C.) for 10 hours to obtain 12.5 g of conductive polyaniline having tetrafluoroboric acid as a dopant (hereinafter simply referred to as “conductive polyaniline”). The conductive polyaniline was a bright green powder. Therefore, the low molecular anion (X) incorporated during the polymerization of the conductive polymer (W) is tetrafluoroboric acid (BF ₄ ⁻ ).

(Conductivity of conductive polyaniline powder)
After pulverizing 130 mg of the conductive polyaniline powder in a smoked mortar, vacuum-pressure molding was performed for 10 minutes under a pressure of 75 MPa using a KBr tablet molding machine for infrared spectrum measurement, and a conductive polyaniline disk having a thickness of 720 μm was formed. Obtained. The conductivity of the disk measured by the 4-terminal method conductivity measurement by the Van der Pau method was 19.5 S / cm.

[Multiple negatively charged anionic materials (Y)]
A 50 wt% aqueous solution of sulfosuccinic acid (manufactured by Aldrich, molecular weight 196) was prepared as a dope solution and adjusted to a temperature of 65 ° C. Sulfosuccinic acid is an anionic material having two carboxylic acids, one sulfonic acid and three anionic groups.

[Polymer anion (Z)]
As polymer anion (Z), polyacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd., weight average molecular weight 1 million) was used, and lithium hydroxide equivalent to ½ equivalent of carboxylic acid was added in an aqueous solution to a concentration of 4.4 wt% A uniform and viscous lithium polyacrylate aqueous solution was prepared. In the polyacrylic acid, about 50% of the carboxyl groups were lithium-chlorinated.

<Step of Dedoped X Component from Conductive Polymer (W) (Step a)>
The conductive polyaniline powder in a doped state incorporating the tetrafluoroboric acid (BF ₄ ⁻ ) obtained as described above is placed in a 2 mol / L sodium hydroxide aqueous solution and stirred for 30 minutes in a 3 L separable flask. The dopant tetrafluoroboric acid was dedoped by a neutralization reaction. The dedoped polyaniline was washed with water until the filtrate became neutral, then stirred and washed in acetone, and filtered under reduced pressure using a Buchner funnel and a suction bottle to obtain a dedoped polyaniline powder on No. 2 filter paper. . This was vacuum-dried at room temperature for 10 hours to obtain a brown undoped polyaniline powder.

<Step of Protonic Acid Doping of Conductive Polymer (W) with Y Component (Step b)>
The dedope polyaniline powder obtained above was dispersed in a 50 wt% aqueous solution of sulfosuccinic acid (Y component) adjusted to 65 ° C. and immersed for 4 hours. Then, after separating by filtration, it wash | cleaned with acetone. Then, it was dried at 50 ° C. for 10 minutes.

  The conductivity of the conductive polyaniline powder in the doped state, incorporating the sulfosuccinic acid (Y) thus obtained, was measured in the same manner by the 4-terminal conductivity measurement by the van der Pau method. The conductivity was 45.0 S / cm.

<Step of forming a positive electrode using at least a doped conductive polymer (W) and a Z component (step c)>
21.0 g of a lithiated polyacrylic acid aqueous solution prepared as the Z component was prepared.

  After mixing 4 g of the conductive polyaniline powder in a doped state incorporating the prepared sulfosuccinic acid and 0.5 g of conductive carbon black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.), this was mixed with 4.4. The mixture was added to 21.0 g of a polyacrylic acid aqueous solution having a concentration of% by weight and kneaded well with a spatula. This was subjected to ultrasonic treatment for 1 minute with an ultrasonic homogenizer to obtain a paste having fluidity. This paste was further defoamed using a vacuum suction bell and a rotary pump.

A table-type automatic coating machine (Tester Sangyo Co., Ltd., PI) is formed on an aluminum foil (30 CB, manufactured by Hosen Co., Ltd.) having a width of 150 mm and a thickness of 30 μm for an electric double layer capacitor in which the defoamed paste is etched. -1210), a film applicator with a micrometer (SA-204) was applied, left at room temperature for 45 minutes, and then dried on a hot plate at 100 ° C. Thereafter, the composite sheet was obtained by pressing for 5 minutes at a temperature of 140 ° C. and a pressure of 15.2 kgf / cm ² using a vacuum press machine (KVHC-PRESS, manufactured by Kitagawa Seiki Co., Ltd.).

  This composite sheet was punched into a disk shape with a punching jig on which a punching blade with a diameter of 15.95 mmφ was installed to obtain a positive electrode sheet. The electrode layer thickness after subtracting the aluminum foil thickness was 274 μm, and the porosity was 67%.

<About cell assembly>
First, before assembling to the cell, the positive electrode sheet punched into the above disk shape, the negative electrode is metal lithium (Honjo Metal Co., coin-type metal lithium, thickness 50 μm), and the separator is non-woven fabric (manufactured by Hosen Co., Ltd.) As an electrolyte, an ethylene carbonate / dimethyl carbonate solution (made by Kishida Chemical Co., Ltd.) of 1 mol / dm ³ lithium tetrafluoroborate (LiBF ₄ ) was prepared. And the prepared positive electrode sheet and separator were vacuum-dried at 100 degreeC for 5 hours using the vacuum dryer. Thereafter, the following assembly was performed in a glove box having a dew point of −100 ° C. in an ultra-high purity argon gas atmosphere.

  First, a positive electrode sheet and a negative electrode were placed facing each other correctly in a stainless steel HS cell (manufactured by Hosen Co., Ltd.) for a non-aqueous electrolyte secondary battery experiment, and the separator was positioned so that they did not short-circuit. Then, the prepared electrolyte weight (mg) was injected 4.5 times with respect to the weight (mg) of polyaniline doped with sulfosuccinic acid.

  That is, electrolyte solution weight (mg) / activated carbon weight (mg) = 4.5 (mg / mg).

(Storage battery performance)
The battery was charged to 3.8 V at a current value of 0.05 mA / cm ² . After reaching 3.8 V, switching to constant potential charging was performed. The battery was left for 30 minutes after charging and then discharged at a current value of 0.05 mA / cm ² until the voltage reached 2V. This was repeated. The weight capacity density at the time of discharge at the 10th charge / discharge cycle was 115 mAh / g.

[Example 2]
First, prior to the production of an electrode for an electricity storage device, the following components were prepared and prepared.

[Preparation of conductive polymer (W)]
A conductive polyaniline powder in a doped state, which was prepared in the same manner as in Example 1 and incorporated tetrafluoroboric acid (BF ₄ ⁻ ), was prepared.

[Multiple negatively charged anionic materials (Y)]
A 30% aqueous solution of polyacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd., weight average molecular weight 25,000) was prepared as a dope solution and adjusted to a temperature of 70 ° C. Polyacrylic acid is an anionic material having a large number of carboxylic acids.

[Polymer anion (Z)]
As in Example 1, a 4.4 wt% concentration uniform and viscous lithium polyacrylate aqueous solution was prepared.

<Step of Dedoped X Component from Conductive Polymer (W) (Step a)>
In the same manner as in Example 1, tetrafluoroboric acid (BF ₄ ⁻ ) was dedoped from the conductive polyaniline powder to obtain a brown undoped polyaniline powder.

<Step of Protonic Acid Doping of Conductive Polymer (W) with Y Component (Step b)>
The dedope polyaniline powder obtained above was dispersed in a 30% by weight aqueous solution of polyacrylic acid adjusted to 70 ° C. and immersed for 4 hours. Then, after separating by filtration, it was washed with acetone and then dried at 50 ° C. for 10 minutes. In this way, a conductive polyaniline powder in a doped state incorporating polyacrylic acid was obtained. The conductivity of this conductive polyaniline powder was measured in the same manner by the 4-terminal method conductivity measurement by the above van der Pau method. As a result, the conductivity was 5.0 × 10 ⁻⁴ S / cm.

<Step of forming a positive electrode using at least a doped conductive polymer (W) and a Z component (step c)>
As the Z component, 21.0 g of the prepared lithium polyacrylate aqueous solution was prepared.

  After mixing 4 g of the conductive polyaniline powder in a doped state incorporating the prepared polyacrylic acid and 0.5 g of conductive carbon black (Denka Black, Denki Kagaku Kogyo Co., Ltd.), The mixture was added to 21.0 g of a 4 wt% lithium polyacrylate aqueous solution and well kneaded with a spatula. This was subjected to ultrasonic treatment for 1 minute with an ultrasonic homogenizer to obtain a paste having fluidity. This paste was further defoamed using a vacuum suction bell and a rotary pump.

  A composite sheet was obtained in the same manner as in Example 1 using the paste thus defoamed.

  This composite sheet was punched into a disk shape with a punching jig on which a punching blade with a diameter of 15.95 mmφ was installed to obtain a positive electrode sheet. The electrode layer thickness minus the aluminum foil thickness was 256 μm, and the porosity was 65%.

<About cell assembly>
A cell was assembled in the same manner as in Example 1.

(Storage battery performance)
The weight capacity density when evaluated in the same manner as in Example 1 was 125 mAh / g.

Example 3
Prior to the production of the electrode for the electricity storage device, the following components were prepared and prepared.

[Preparation of conductive polymer (W)]
A conductive polyaniline powder in a doped state, which was prepared in the same manner as in Example 1 and incorporated tetrafluoroboric acid (BF ₄ ⁻ ), was prepared.

[Multiple negatively charged anionic materials (Y)]
A 50% by weight aqueous solution of 5-sulfosartylic acid dihydrate (manufactured by Aldrich, molecular weight 254) was prepared as a dope solution and adjusted to a temperature of 70 ° C. 5-Sulfosalicylic acid is an anionic material having one carboxylic acid, one sulfonic acid and two anionic groups.

[Polymer anion (Z)]
As in Example 1, a 4.4 wt% concentration uniform and viscous lithium polyacrylate aqueous solution was prepared.

<Step of Dedoped X Component from Conductive Polymer (W) (Step a)>
In the same manner as in Example 1, tetrafluoroboric acid (BF ₄ ⁻ ) was dedoped from the conductive polyaniline powder to obtain a brown undoped polyaniline powder.

<Step of Protonic Acid Doping of Conductive Polymer (W) with Y Component (Step b)>
The polyaniline powder in the dedope state obtained above was dispersed in a 30% by weight aqueous solution of 5-sulfosartylic acid dihydrate adjusted to 85 ° C. and immersed for 5 hours. Then, after separating by filtration, it was washed with acetone and then dried at 50 ° C. for 10 minutes. In this way, a conductive polyaniline powder in a doped state incorporating 5-sulfosartylic acid was obtained. The conductivity of the conductive polyaniline powder was measured in the same manner by the 4-terminal method conductivity measurement by the van der Pau method, and the conductivity was 14.5 S / cm.

<Step c of forming a positive electrode using at least the doped conductive polymer (W) and the Z component>
As the Z component, 21.0 g of a lithium polyacrylate aqueous solution prepared in the same manner as in Example 1 was prepared.

  After mixing 4 g of the conductive polyaniline powder in a doped state incorporating 5-sulfosaltylic acid prepared above and 0.5 g of conductive carbon black (Denka Black, Denki Kagaku Kogyo Co., Ltd.), The mixture was added to 21.0 g of a lithium polyacrylate aqueous solution having a concentration of 4% by weight and kneaded well with a spatula. This was subjected to ultrasonic treatment for 1 minute with an ultrasonic homogenizer to obtain a paste having fluidity. This paste was further defoamed using a vacuum suction bell and a rotary pump.

  A composite sheet was obtained in the same manner as in Example 1 using the paste thus defoamed.

  This composite sheet was punched into a disk shape with a punching jig on which a punching blade with a diameter of 15.95 mmφ was installed to obtain a positive electrode sheet. The electrode layer thickness minus the aluminum foil thickness was 205 μm, and the porosity was 67%.

<About cell assembly>
A cell was assembled in the same manner as in Example 1.

(Storage battery performance)
The weight capacity density when evaluated in the same manner as in Example 1 was 115 mAh / g.

Example 4
Prior to the production of the electrode for the electricity storage device, the following components were prepared and prepared.

[Preparation of conductive polymer (W)]
A conductive polyaniline powder in a doped state was prepared in the same manner as in Example 1 and incorporating tetrafluoroboric acid (BF ₄ ⁻ ).

[Multiple negatively charged anionic materials (Y)]
A 50% by weight aqueous solution of 5-sulfosartylic acid dihydrate (manufactured by Aldrich, molecular weight 254) was prepared as a dope solution and adjusted to a temperature of 70 ° C. 5-Sulfosalicylic acid is an anionic material having one carboxylic acid, one sulfonic acid and two anionic groups.

[Polymer anion (Z)]
As in Example 1, a 4.4 wt% concentration uniform and viscous lithium polyacrylate aqueous solution was prepared.

<Step of Dedoped X Component from Conductive Polymer (W) (Step a)>
In the same manner as in Example 1, tetrafluoroboric acid (BF ₄ ⁻ ) was dedoped from the conductive polyaniline powder to obtain a brown undoped polyaniline powder. Furthermore, the obtained powder was put into a methanol solution of phenylhydrazine and subjected to a reduction treatment for 30 minutes with stirring. The polyaniline powder changed its color from brown to gray to obtain a reduced / dedoped polyaniline powder.

<Step of Protonic Acid Doping of Conductive Polymer (W) with Y Component (Step b)>
The polyaniline powder in the reduced / dedope state obtained above was dispersed in a 30% by weight aqueous solution of 5-sulfosartylic acid dihydrate adjusted to 85 ° C. and immersed for 5 hours. Then, after separating by filtration, it was washed with acetone and then dried at 50 ° C. for 10 minutes. In this way, a conductive polyaniline powder in a doped state incorporating 5-sulfosartylic acid was obtained. The conductivity of this conductive polyaniline powder was measured in the same manner by the 4-terminal method conductivity measurement by the van der Pau method, and the conductivity was 0.4 S / cm.

<Step c of forming a positive electrode using at least the doped conductive polymer (W) and the Z component>
As the Z component, 21.0 g of a lithium polyacrylate aqueous solution prepared in the same manner as in Example 1 was prepared.

  After mixing 4 g of the conductive polyaniline powder in a doped state incorporating 5-sulfosaltylic acid prepared above and 0.5 g of conductive carbon black (Denka Black, Denki Kagaku Kogyo Co., Ltd.), The mixture was added to 21.0 g of a lithium polyacrylate aqueous solution having a concentration of 4% by weight and kneaded well with a spatula. This was subjected to ultrasonic treatment for 1 minute with an ultrasonic homogenizer to obtain a paste having fluidity. This paste was further defoamed using a vacuum suction bell and a rotary pump.

  A composite sheet was obtained in the same manner as in Example 1 using the paste thus defoamed.

  This composite sheet was punched into a disk shape with a punching jig on which a punching blade with a diameter of 15.95 mmφ was installed to obtain a positive electrode sheet. The electrode layer thickness minus the aluminum foil thickness was 177 μm, and the porosity was 64%.

<About cell assembly>
A cell was assembled in the same manner as in Example 1.

(Storage battery performance)
The weight capacity density when evaluated in the same manner as in Example 1 was 122 mAh / g.

  The components used in the battery cells of Examples 1 to 4 and the weight capacity density of the battery cells are shown in Table 1 below.

  From the said result, it turned out that the weight capacity density of the battery cell of Examples 1-4 is a sufficiently large value, and even larger capacity density is obtained even if it compares with an electric double layer capacitor. Therefore, even if the dopant is changed, it can be seen that a novel electricity storage device having sufficient battery performance can be obtained, and a dopant suitable for the electrode for the electricity storage device can be selected, and the range of material design can be expanded.

  The method for producing an electrode for an electricity storage device of the present invention can be suitably used as a method for producing an electrode for an electricity storage device such as a lithium secondary battery. In addition, the power storage device obtained by the production method of the present invention can be used for the same applications as conventional secondary batteries. For example, portable electronic devices such as portable PCs, cellular phones, and personal digital assistants (PDAs), and hybrid devices Widely used in power sources for driving electric vehicles, electric vehicles, fuel cell vehicles and the like.

1 Current collector (for positive electrode)
2 Positive electrode 3 Electrolyte layer 4 Negative electrode 5 Current collector (for negative electrode)

Claims (4)

A method for producing at least one of the positive electrode and the negative electrode of an electricity storage device having an electrolyte layer and a positive electrode and a negative electrode provided opposite to each other with the electrolyte layer interposed therebetween. )-(Z) molecular size is (X) <(Y) <(Z), The manufacturing method of the electrode for electrical storage devices characterized by the above-mentioned.
a. A step of dedoping the low molecular anion (X) from the conductive polymer (W).
b. A step of proton acid doping a plurality of negatively charged anionic materials (Y) to the conductive polymer (W) obtained by the step a.
c. A step of forming an electrode using at least the conductive polymer (W) obtained by the step b and the polymer anion (Z).   The process for producing an electrode for an electricity storage device according to claim 1, wherein the polymer anion (Z) serves as a binder for the electrode.   An electrode for an electricity storage device obtained by the method for producing an electrode for an electricity storage device according to claim 1 or 2. An electrical storage device using the electrode according to claim 3.

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