JP2014127446A - Method for manufacturing power storage device electrode, 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 obtaining a new power storage device having sufficient battery performance by carrying out appropriate processing at the time of electrode fabrication.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 and b: a step a, in which proton acid (X) is turned into conductive polymer (W) by proton acid processing; a step b, in which an electrode is formed using the conductive polymer (W) in a dope state obtained by the step a, and 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.

  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, by using a conductive polymer for the positive electrode and further using a polyvalent dopant such as a polymer anion as a dopant, it is possible to increase the capacity of the rocking chair type battery by reducing the amount of electrolyte.

  However, in general, an electrode using a conductive polymer cannot reliably exhibit its theoretical capacity.

  On the other hand, a technology that enables a conductive polymer such as polyaniline to be highly conductive using a dopant such as camphorsulfonic acid and a treating agent such as cresol has been disclosed (Synthetic Metals 65 (1994) 103-106 AG MacDiarmid, et al.), but no major developments have been made to improve battery performance.

  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 a sufficient battery can be obtained by performing appropriate processing during electrode production. It is an object of the present invention to provide a method for producing an electrode for an electricity storage device capable of obtaining a novel electricity storage device having performance, an electrode obtained thereby, and an electricity 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 provided with the process of a and b is made into a 1st summary.
a. A step of treating the protonic acid (X) with the protonic acid to the conductive polymer (W).
b. A step of forming an electrode using the doped conductive polymer (W) obtained by the step a and a 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.

  Furthermore, this invention makes the 3rd summary the electrical storage device using the said electrode for electrical storage devices.

  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 energy storage device mechanism, which is a cation transfer type that requires only a small amount of electrolyte, and conducted various experiments focusing on this mechanism. As a result, the present inventors can easily and quickly manufacture a novel electricity storage device having sufficient battery performance and obtain an electricity storage device having sufficient battery characteristics by performing an appropriate treatment during electrode production. The present inventors have found a method for manufacturing a power storage device that can be used and have reached the present invention.

  The process for producing an electrode for an electricity storage device of the present invention comprises a step (a step) of treating a protonic acid (X) with a conductive polymer (W) (a step), and a doped conductive polymer (W) obtained by the step a. ) And a step of forming an electrode using the polymer anion (Z) (step b), an electricity storage device having sufficient battery performance can be obtained.

  And in the manufacturing method of the electrode for electrical storage devices of this invention, the said b process is a mixture which consists of the conductive polymer (W) of the dope state obtained by the said a process, and a phenol type organic compound (Y), and a polymer. In the step of forming an electrode using an anion (Z) (step b ′), an electricity storage device having 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. 3 is a graph showing capacity densities of Examples 1 and 2 and Comparative Example 1. FIG.

  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 and b.
a. A step of treating the protonic acid (X) with the protonic acid to the conductive polymer (W).
b. A step of forming an electrode using the doped conductive polymer (W) obtained by the step a and a polymer anion (Z).

  In addition, as described above, in the method for producing an electrode for an electricity storage device of the present invention, the step b includes a conductive polymer (W) in a doped state obtained by the step a and a phenolic organic compound (Y). And a polymer anion (Z) may be used to form an electrode (step b ′). In this case, the electricity storage device has a higher capacity density and a higher initial charge / discharge capacity density. Is preferable.

  The electrode according to the present invention can be used for both a positive electrode and a negative electrode of an electricity storage device, but is particularly preferably used as a positive electrode. 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.

  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 electrodes will be described in order.

<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. Usually, the conductive polymer material is in a doped state, but in the present invention, a dedoped conductive polymer is preferably used as described later.

  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.

<Protonic acid (X)>
The protonic acid (X) is a dopant for the conductive polymer (W). For example, camphorsulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, vinylsulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfone. Examples include acids, organic sulfonic acids such as methanesulfonic acid, sulfuric acid, hydrochloric acid and the like. Of these, camphorsulfonic acid is particularly preferable.

  The protonic acid (X) 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 in

<Phenolic organic compound (Y)>
Examples of the phenolic organic compound (Y) include cresols such as m-cresol, p-cresol, 4,6-di-t-butyl-m-cresol, xylenols such as 2,4-xylenol, p. -Alkylphenols such as ethylphenol, 6-t-butyl-2-methylphenol, 2-chlorophenol and 2-fluorophenol. Among these, cresols are particularly preferably used.

  The phenolic organic compound (Y) is usually 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). It is used in the range.

<Polymer anion (Z)>
The polymer anion (Z) is a negatively charged polymer, and examples thereof include polysulfonic acid, polyphosphonic acid, and polycarboxylic acid, and polycarboxylic acid is particularly 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. These may be used alone or in combination of two or more. Among these, polyacrylic acid and polymethacrylic acid are particularly preferably used.

  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.

  The polymer anion (Z) preferably serves as a binder and has a high molecular weight in order to become a fixed anion for forming a rocking chair type battery when forming a battery device.

  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) with respect to the W component is too small, it tends to be impossible to obtain an electricity storage device excellent in energy density. On the other hand, if the amount of the polymer anion (Z) with respect to the W component is too large, There is a tendency that an energy storage device having a high energy density cannot be obtained.

  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 (acetylene black).

  The blending amount of the conductive assistant is preferably 1-30 parts by weight, more preferably 4-20 parts by weight, and 8-18 parts by weight with respect to 100 parts by weight of the conductive polymer (W). Part is particularly preferred.

  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 described above, according to the method for producing an electrode for an electricity storage device of the present invention, an electrode is formed through the following steps a and b. Hereinafter, steps a and b will be described in order.
a. A step of treating the protonic acid (X) with the protonic acid to the conductive polymer (W).
b. A step of forming an electrode using the doped conductive polymer (W) obtained by the step a and a polymer anion (Z).

(About step a)
First, the step a includes a step of treating the protonic acid (X) with the protonic acid (W). For example, the conductive polymer (W) in a doped state is obtained by stirring the powder of the conductive polymer (W) in a solution of a protonic acid.

(About step b)
Next, the step b is a step of forming an electrode using the doped conductive polymer (W) obtained in the step a and a polymer anion (Z). Z) is dissolved in water to form an aqueous solution, and a conductive polymer (W) in a doped state obtained by the above step a and, if necessary, a conductive additive, a binder, etc. are added thereto and sufficiently dispersed. Prepare a paste. A composite of a mixture of a W component and a Z component (optional components such as a conductive additive and a binder as required) is formed on the current collector by evaporating water after applying this on the current collector. As a result, a sheet electrode can be obtained.

(About step b ')
As described above, in the method for producing an electrode for an electricity storage device of the present invention, the step b comprises a doped conductive polymer (W) obtained by the step a and a phenolic organic compound (Y). The step of forming an electrode using the mixture and the polymer anion (Z) (step b ′) may be used. For example, in the aqueous solution of the phenolic organic compound (Y), a doped conductive polymer ( There is a method by dispersing W). Other than that, a sheet electrode as a composite of a mixture of a W component, a Y component, and a Z component (optional components such as a conductive assistant and a binder, if necessary) on the current collector in the same manner as in step b above. Can be obtained.

<About electrodes for power storage devices>
In the electrode formed as described above, a layer of a mixture of a protonic acid (X), a polymer anion (Z), a conductive polymer (W), and, if necessary, a phenolic organic compound (Y). Is fixed in the electrode.

  The electrode is preferably formed on a porous sheet. Usually, the thickness of the positive electrode is preferably 1 to 1000 μm, and more preferably 10 to 700 μm.

  The thickness of the electrode is obtained by measuring the electrode using a dial gauge (manufactured by Ozaki Mfg. Co., Ltd.), which is a flat plate having a tip shape of 5 mm in diameter, and obtaining an average of 10 measurement values with respect to the surface of the electrode. . When an electrode (porous layer) is provided on the current collector and composited, the thickness of the composite is measured in the same manner as described above, the average of the measured values is obtained, and the thickness of the current collector is subtracted. Thus, the thickness of the electrode can be obtained.

  Next, the configuration of the electricity storage device will be described in the case where the electrode according to the electricity storage device of the present invention is used as the positive electrode 2.

<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.
In addition, the electrode obtained by the manufacturing method of this invention can also be used for a negative electrode, and may be used for both a positive electrode and a negative electrode.

  In addition to the positive electrode, the electrolyte layer, and the counter electrode, the power storage device can use a separator, and 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 production method of the present invention, by performing an appropriate treatment (the above-mentioned steps a and b) at the time of producing an electrode, a novel electrode for an electricity storage device having sufficient battery performance, and a capacity density and an electrode per weight of active material A high-performance power storage device having an excellent capacity density per volume can be easily produced.

  The details of why sufficient performance is obtained in this way are unclear, but the protonic acid (X) and the phenolic organic compound (Y) used as the need arises cause the chain of the conductive polymer (W). It can be considered that by extending the film, it contributes to improvement of electron conduction and ion conductivity in charging / discharging of the battery.

  In addition, as the charge / discharge mechanism of the electricity storage device of the present invention, the polymer anion (Z) is used as a binder, and the binder itself functions as a dopant, and there is a part of a rocking chair type mechanism. is assumed. 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.

  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) was added, To this was added 10.0 g (0.107 mol) of aniline with stirring. 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.

(Conductivity of conductive polyaniline powder)
After pulverizing 130 mg of the conductive polyaniline powder in a smoked mortar, vacuum-pressing was performed for 10 minutes under a pressure of 300 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.

  The conductive polyaniline powder in the doped state thus obtained is put in a 2 mol / L aqueous sodium hydroxide solution, stirred for 30 minutes to neutralize the conductive polyaniline, and tetrafluoroboric acid as a dopant. Was dedoped from polyaniline. The dedoped polyaniline is washed with water until the filtrate becomes neutral, then stirred and washed in acetone, filtered under reduced pressure using a Buchner funnel and a suction bottle, and dedoped polyaniline powder on No. 2 filter paper. Got. This was vacuum-dried at room temperature for 10 hours to obtain a polyaniline powder (brown powder) in a dedope state.

  Next, the dedope polyaniline powder thus obtained was put in a methanol solution of phenylhydrazine and subjected to a reduction treatment with stirring for 30 minutes. The polyaniline powder changed its color from brown to gray.

  After such a reduction treatment, the obtained polyaniline powder was washed with methanol and then with acetone, filtered, and then vacuum-dried at room temperature to obtain a reduced dedope polyaniline (reduced polyaniline). .

After pulverizing 130 mg of the above polyaniline powder in the reduced dedope state in a smoked mortar, vacuum reduced 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 reduced dedope having a thickness of 720 μm. A polyaniline disk in state was obtained. The electric conductivity of the disk measured by the 4-terminal conductivity measurement by the Van der Pau method was 4.7 × 10 ⁻⁶ S / cm.

<Process of Protic Acid (X) Protonic Acid Treatment to Conductive Polymer (W) (Process a)>
After pulverizing 2.13 g of the polyaniline powder in the reduced and dedope state in a smoked mortar, an aqueous solution of camphorsulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd., model number 21814) previously adjusted to 50% by weight with ion-exchanged water is used. 67 g was added and stirred with a stir bar to obtain a protonic acid-treated polyaniline powder.

<The step of forming an electrode using the conductive polymer (W) in the doped state obtained by the step a and the mixture of the phenolic organic compound (Y) and the polymer anion (Z) (step b ′) )>

  First, 1.3 g of m-cresol (manufactured by Wako Pure Chemical Industries, model number 303-20925), which is a phenolic organic compound (Y), is added to the polyaniline powder (W) treated with the proton acid to obtain a mixture. It was.

  Next, an electrode is formed using a mixture of the doped polyaniline powder (W) obtained above and a phenolic organic compound (Y), and a polymer anion (Z) prepared as follows. did.

[Preparation of polymer anion (Z)]
Polyacrylic acid (manufactured by Nippon Shokubai Co., Ltd., weight average molecular weight 800,000) is used as the polymer anion (Z), and lithium hydroxide equivalent to the carboxylic acid is added in an aqueous solution. An aqueous polyacrylic acid solution was prepared. In the polyacrylic acid, about 100% of the carboxyl groups were lithium-chlorinated.

  0.6 g of conductive carbon black (acetylene black) (manufactured by Denki Kagaku Kogyo Co., Ltd.) powder was mixed with the mixture of the prepared polyaniline powder (W) and the phenolic organic compound (Y) prepared above. Thereafter, a polymer anion (Z) equivalent to ½ equivalent of N element of polyaniline powder (W) treated with proton acid (14.5 g of 7.5 wt% polyacrylic acid aqueous solution) was added and stirred with a stirring bar. Kneaded. This was subjected to a dispersion treatment for 6 minutes with an ultrasonic homogenizer to obtain a dispersion having fluidity. This dispersion was subjected to a mild dispersion treatment using a high shear force in a disperser film mix 40-40 manufactured by Plymix Co., to obtain a paste having fluidity. The paste was further stirred and defoamed using a hybrid mixer Awatori Nertaro MH-500 manufactured by THNKY.

  Using a desktop automatic coating machine (Tester Sangyo Co., Ltd., PI-1210) on a 150 mm wide, 30 μm thick aluminum foil (30CB manufactured by Hosen Co., Ltd.) obtained by etching the defoamed paste in this manner. The film was applied using a film applicator with a micrometer (SA-204), allowed to stand at room temperature for 45 minutes, and then dried on a hot plate at 100 ° C. to obtain a composite sheet.

  Next, the composite sheet thus obtained is cut into a size of 35 mm × 27 mm, and a part of the active material is removed so that the active material layer of the composite sheet has an area of 27 mm × 27 mm, The part from which the part of the active material layer was removed was used as a tab electrode attachment part, and an aluminum tab was welded to the composite sheet using a precision resistance welding machine (NSW System, NSW-15) to obtain a positive electrode sheet. . The thickness of the composite sheet on the aluminum foil was 100 μm when calculated by subtracting the thickness of the 30 μm thick aluminum foil.

<About cell assembly>
First, a negative electrode material, an electrolytic solution, and a separator were prepared and prepared before assembly into a cell.

[Production of negative electrode material]
The lithium metal foil roll was cut into a 29 mm x 29 mm dimension in a rolled lithium foil (Honjo Metal Co., Ltd., 29 mm wide, 0.05 mm thick) glove box as the negative electrode, and the mesh-like 35 mm x 29 mm SUS was nickel. The negative electrode sheet was produced by pressing and adhering the tab to a previously welded one by ultrasonic welding.

[Preparation of electrolyte]
An ethylene carbonate / dimethyl carbonate solution (LBG00022 manufactured by Kishida Chemical Co., Ltd.) of lithium hexafluorophosphate (LiPF ₆ ) having a concentration of 1 mol / dm ³ was prepared.

[Preparation of separator]
A nonwoven fabric (manufactured by Hosen Co., Ltd., TF40-50, porosity: 55%) was prepared.

  Next, the metallic lithium negative electrode, separator, positive electrode, aluminum laminate film, and tab film were all dried in a glove box (with a dew point of -100 ° C. in a glove box immediately after drying at 80 ° C. for 2 hours in a vacuum dryer). In an ultra-high purity argon gas atmosphere). The metallic lithium negative electrode, the separator, and the positive electrode were combined so that the negative electrode and the positive electrode were not in contact with each other, and sandwiched between aluminum laminate films and heat sealed. The electrode tab portion was heat-sealed with the tab film sandwiched between them for the purpose of improving the adhesion with the aluminum laminate film. The electrolytic solution was added so as to be 0.01 times the weight of the polyaniline used, and then sealed by heat sealing to produce a laminated cell lithium secondary battery.

(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. At this time (first time), the discharge capacity per weight of the conductive polymer was 147 mAh / g. The discharge capacity in the charge / discharge cycle thereafter is shown in FIG.

[Example 2]
In Example 1, the process of forming an electrode using the mixture which consists of the conductive polymer (W) of the dope state obtained by said process a, a phenolic organic compound (Y), and a polymer anion (Z). Instead of (step b ′), a step not using a phenolic organic compound (Y), that is, using a doped conductive polymer (W) obtained by step a and a polymer anion (Z) A composite sheet was produced in the same manner as in Example 1 except that the step was changed to the step of forming an electrode (step b). The thickness of this composite sheet was 95 μm. And the laminated cell lithium secondary battery was produced using this composite sheet, and storage battery performance was evaluated.

  The discharge capacity per weight of the first conductive polymer was 82 mAh / g. Thereafter, the discharge capacity in the charge / discharge cycle is also shown in FIG.

[Comparative Example 1]
In Example 1, without performing any of the above steps a and b ′, instead of 14.5 g of a 7.5 wt% polyacrylic acid aqueous solution as polymer anion (Z), styrene-butadiene rubber (SBR) was used. ) Emulsion (manufactured by JSR, TRD2001, SBR content 48 wt%) 0.31 g and poly (N-vinylpyrrolidone) aqueous solution (manufactured by Nippon Shokubai Co., Ltd., K-90W, content 19.8 wt%) 0.21 g A composite sheet was prepared in the same manner as in Example 1 except that a solution in which the above was mixed was used. The thickness of this composite sheet was 90 μm. And the laminated cell lithium secondary battery was produced using this composite sheet, and storage battery performance was evaluated.

  The discharge capacity per weight of the conductive polymer for the first time was 63 mAh / g. Thereafter, the discharge capacity in the charge / discharge cycle is also shown in FIG.

  From the above results, Example 1 exhibited a high capacity of 147 mAh / g at the first charge / discharge, and the subsequent cycle characteristics were also stable. In Example 2, the capacity at the first charge / discharge was 82 mAh / g, which is lower than that in Example 1, but the capacity was improved by the cycle thereafter.

  On the other hand, in Comparative Example 1, the capacity at the first charge / discharge was as low as 63 mAh / g, and after that, the capacity was improved by the cycle, but stopped at 100 mAh / g.

  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, comprising the following steps a and b: The manufacturing method of the electrode for electrical storage devices.
a. A step of treating the protonic acid (X) with the protonic acid to the conductive polymer (W).
b. A step of forming an electrode using the doped conductive polymer (W) obtained by the step a and a polymer anion (Z).   The step b is a step of forming an electrode using a mixture of the doped conductive polymer (W) obtained by the step a and a phenolic organic compound (Y) and a polymer anion (Z). The manufacturing method of the electrode for electrical storage devices of Claim 1 which is these.   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 electricity storage device comprising the electricity storage device electrode according to claim 3.

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