JP2015165481A - Electrode and power storage device using the same - Google Patents

Abstract

An electrode having a high discharge voltage and a high capacity density and a high energy density, and an electricity storage device using the same are provided. An electrode having an electrode layer on at least a part of a surface of a current collector, wherein the electrode layer includes the following (A) to (D). (A) Conductive polymer. (B) Disulfide polymer. (C) Conductivity aid. (D) Binder. [Selection diagram] Figure 1

Description

  The present invention relates to an electrode and an electricity storage device using the electrode.

  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 that the material used as an electrode has a high capacity and high rate characteristics.

  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 of the active material is also referred to as so-called doping / dedoping, and the amount of doping / dedoping per certain molecular structure is called the doping rate (or doping rate). As a result, the capacity can be increased.

  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 increased capacity.

  Among these lithium secondary batteries, a lithium-containing transition metal oxide such as lithium manganate or lithium cobaltate is used as the positive electrode active material, and a carbon material capable of inserting and removing lithium ions from the negative electrode is used. A lithium secondary battery in which both electrodes are opposed to each other in an electrolyte solution has a high energy density, and is therefore widely used as an electricity storage device for the electronic device described above.

  In recent years, studies have been made to improve the capacity density per weight of the electrode active material in order to further increase the capacity. For example, when the positive electrode of a power storage device is a manganese silicon-based positive electrode using a lithium-containing transition metal oxide as an electrode active material, it has been reported that the capacity density of the power storage device is 220 Ah / kg (non-patent) Reference 1).

  In addition, when a disulfide-based, quinone-based, diazine-based, or radialene-based low molecular weight organic compound is used as the positive electrode active material of the power storage device, the maximum capacity density of the power storage device should be about 500 Ah / kg. Has also been reported (see Non-Patent Document 2).

  However, when an organic low molecular weight compound as described above is used as an electrode active material, the voltage during discharge is significantly smaller than that of an electricity storage device using a lithium-containing transition metal oxide as an electrode active material, and in terms of energy density. There is a disadvantage. Therefore, an electrode in which an organic low-molecular compound as described above and an organic conductive polymer that can expect a higher voltage are combined has also been proposed (see Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 9-259864 Japanese Patent Laid-Open No. 6-20692 JP2012-229329A

GS Yuasa Technical Report, December 2010, Vol. 7, No. 2, pp. 12-18 Nikkei Electronics, December 13, 2010, pages 73-82

  However, these organic low molecular weight active materials are remarkably reduced in capacity due to charge / discharge cycles, and organic low molecular weight active materials that can withstand repeated charge / discharge necessary for practical use have not yet been obtained.

  On the other hand, as an organic polymer active material, it is known that an active material using a conductive polymer such as polyaniline, polypyrrole or polythiophene exhibits a relatively high discharge voltage. However, the capacity density is small, and the maximum is about 150 Ah / kg per active material weight.

  In recent years, an active material using an organic sulfur polymer has attracted attention (Patent Document 3). Although these have a low discharge voltage, they have a high capacity density (about 350 Ah / kg) and are attracting attention as next-generation organic active material materials. However, an active material that can express a high capacity and a high energy density having a high discharge voltage has not yet been obtained.

  The present invention has been made in view of the circumstances as described above, and an object thereof is to provide an electrode having a high discharge voltage, a high capacity density and a high energy density, and an electricity storage device using the electrode.

In order to achieve the above object, the present invention provides an electrode including an electrode layer on at least a part of a current collector surface, wherein the electrode layer includes the following (A) to (D): To do.
(A) Conductive polymer.
(B) Disulfide polymer.
(C) Conductive aid.
(D) Binder.

  Further, 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, wherein the positive electrode is the electrode described in the first aspect, and the negative electrode inserts and desorbs ions. A power storage device including at least one selected from the group consisting of a compound to be obtained and a metal is a second gist.

  That is, the present inventors have intensively studied to solve the above problems. In the course of the study, the present inventors have found that the electrode layer formed on at least a part of the current collector surface is composed of a conductive polymer (A), a disulfide polymer (B), a conductive auxiliary agent (C), and a binder ( It has been found that an electrode forming material containing D) has a high discharge voltage and exhibits a high capacity density and a high energy density, and has reached the present invention.

Thus, the electrode of the present invention is an electrode having an electrode layer on at least a part of the current collector surface, and the electrode layer includes the following (A) to (D). The stored electricity storage device has a high capacity density and a high energy density with a high discharge voltage.
(A) Conductive polymer.
(B) Disulfide polymer.
(C) Conductive aid.
(D) Binder.

  Further, when the disulfide polymer (B) is a compound having a structure represented by the following formula (1), the capacity density and the energy density are more excellent.

(—S—X—S—S—Y—S—) _n (1)
[In the above formula (1), X and Y each represents an organic group, which may be the same or different from each other. N represents a positive natural number. ]

  Moreover, when the weight average molecular weight of the disulfide polymer (B) is 5,000 to 100,000, the capacity density and the energy density are further improved.

  When the conductive polymer (A) is at least one selected from the group consisting of polyaniline, polyaniline derivative, polypyrrole, polypyrrole derivative, polythiophene and polythiophene derivative, the obtained electricity storage device has higher capacity density and higher capacity. It has energy density.

  Further, 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, wherein the positive electrode is the electrode described above, and the negative electrode includes a compound and a metal that can insert and desorb ions. When it contains at least one selected from the group, it has a high capacity density and a high energy density having a high discharge voltage.

It is sectional drawing which shows the structure of the electrode of this invention. It is sectional drawing which shows the structure of the electrical storage device 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.

<About electrodes>
As shown in FIG. 1, the electrode of the present invention is formed by laminating an electrode layer 7 and a current collector 6, and the electrode layer 7 includes a conductive polymer (A) and a disulfide polymer (B ), A conductive additive (C), and a binder (D). In addition to the above components (A) to (D), for example, other optional components may be added to the electrode forming material. As the current collector 6, a metal foil or mesh such as carbon paper, carbon non-woven fabric, carbon cloth, nickel, aluminum, stainless steel, or copper is appropriately used.

  In the present invention, the electrode active material refers to a substance whose conductivity changes due to insertion / desorption of ions. FIG. 1 schematically shows the structure of the electrode, and the thickness of each layer is different from the actual one.

  As described above, the electrode forming material of the present invention (the material of the electrode layer 7) contains a conductive polymer (A), a disulfide polymer (B), a conductive additive (C), and a binder (D). To do.

[Conductive polymer (A)]
The conductive polymer (A) means that an ionic species is inserted into or desorbed from a polymer in order to compensate for a change in charge generated or lost by an oxidation reaction or reduction reaction of the polymer main chain. Refers to a group of polymers in which the conductivity of the polymer itself changes.

  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 (A) in the present invention.

  In addition, one of the preferred conductive polymers (A) of the present invention is at least one selected from the group consisting of an inorganic acid anion, a fatty acid sulfonate anion, an aromatic sulfonate anion, a polymer sulfonate anion, and a polyvinyl sulfate anion. A polymer having two protonic acid anions as dopants. Further, another conductive polymer preferable in the present invention is a polymer in a dedope state obtained by dedoping the conductive polymer.

  Specific examples of the conductive polymer (A) include, for example, polyacetylene, polypyrrole, polyaniline, polythiophene, polyfuran, polyselenophene, polyisothianaphthene, polyphenylene sulfide, polyphenylene oxide, polyazulene, poly (3,4-ethylenediethylene). Oxythiophene) and the like and various derivatives thereof. Of these, polyaniline, polyaniline derivatives, polypyrrole, polypyrrole derivatives, polythiophene and polythiophene derivatives having a large electrochemical capacity are preferably used, and polyaniline and polyaniline derivatives are more preferably used.

  In the present invention, the polyaniline means a polymer obtained by electrolytic polymerization or chemical oxidative polymerization of aniline, and the polyaniline derivative is obtained by electrolytic polymerization or chemical oxidative polymerization of an aniline derivative, for example. Refers to the polymer produced.

  More specifically, as a derivative of aniline, 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, or an alkoxyalkyl group is provided at a position other than the 4-position of aniline. What has at least one can be illustrated. Preferable specific examples include, for example, o-substituted anilines such as o-methylaniline, o-ethylaniline, o-phenylaniline, o-methoxyaniline, o-ethoxyaniline, m-methylaniline, m-ethylaniline, m And m-substituted anilines such as -methoxyaniline, m-ethoxyaniline, m-phenylaniline and the like. These may be used alone or in combination of two or more. In the present invention, p-phenylaminoaniline having a substituent at the 4-position can be suitably used as an aniline derivative because polyaniline is obtained by oxidative polymerization.

[Disulfide polymer (B)]
The disulfide polymer (B) refers to an organic sulfur polymer compound having a disulfide group (—S—S—) in which two sulfur atoms are linked. For example, 2,5-dimercapto-1,3,4-thiadiazole, 1,4-benzenedithiol, 1,2-benzenedithiol, 1,2-ethanedithiol, tetra (ethylene glycol) dithiol, biphenyl-4,4- Examples include polymer materials obtained by polymerization from monomers such as dithiol, hexa (ethylene glycol) dithiol, and polyethylene glycol dithiol.

  Specifically, the disulfide polymer (B) has a structure represented by the following formula (1).

(—S—X—S—S—Y—S—) _n (1)
[In the above formula (1), X and Y each represents an organic group, which may be the same or different from each other. N represents a positive natural number. ]

  Examples of the organic group X in the above formula (1) include ethylene group, 1,3-propylene group, 1,4-butylene group, 1,4-phenylene group, 1,3-phenylene group, 1,2- A phenylene group etc. can be mentioned. Further, a pyridinylene group in which two hydrogen atoms of the pyridine ring are substituted, for example, 2,3-pyridinylene group, 2,4-pyridinylene group, 2,5-pyridinylene group, 3,5-pyridinylene group, or naphthalene A naphthylene group in which two hydrogen atoms in the ring are substituted, for example, a 1,5-naphthylene group, a 1,8-naphthylene group, and the like can also be exemplified. Of these, an alkylene group or an aryl group is preferable.

  In addition, as the organic group Y in the above formula (1), the same functional groups as the organic group X are listed.

  N in the above formula (1) is a positive natural number, but is preferably 2 or more, more preferably 3 or more, and 10 or more, and particularly preferably n is 20 or more and 800 or less.

  The disulfide polymer (B) is preferably a compound represented by the following formula (2).

  In the above formula (2), n represents a positive natural number as described above, but is preferably 2 or more, more preferably 3 or more, and 10 or more, and particularly preferably n is 20 or more and 800 or less. .

  The weight average molecular weight of the disulfide polymer (B) is preferably 5,000 to 100,000, more preferably 10,000 to 100,000, and particularly preferably 10,000 to 50,000. . This is because if the weight average molecular weight is too large, purification of the disulfide polymer tends to be difficult, while if the weight average molecular weight is too small, the cycle characteristics tend to be inferior. The weight average molecular weight is a value when measured by gel permeation chromatography (GPC) with a polystyrene standard.

  The weight ratio of the disulfide polymer (B) to the conductive polymer (A) (disulfide polymer / conductive polymer) is preferably 1/10 to 10/1 from the viewpoint of improving the capacity density of the electricity storage device, Furthermore, it is preferable that it is 1 / 4-4 / 1.

  Moreover, it is preferable that the ratio of the said conductive polymer (A) and disulfide polymer (B) is 1 to 40 weight% of the whole electrode forming material, More preferably, it is 1 to 30 weight%, More preferably, it is 2 to 20 It is in the range of wt%. This is because if these components (A) and (B) are too much, an electricity storage device having a high capacity density tends not to be obtained, and if it is too little, the electrode formability tends to be inferior.

  As described above, the electrode-forming material of the present invention contains, in addition to the conductive polymer (A) and the disulfide polymer (B), a conductive auxiliary agent (C) and a binder (D) described below.

[Conductive aid (C)]
The conductive auxiliary agent (C) may be any conductive material whose property does not change depending on the potential applied during discharging of the electricity storage device, and examples thereof include conductive carbon materials and metal materials, among which acetylene black, Conductive carbon black such as ketjen black, graphite such as natural graphite and artificial graphite, and fibrous carbon materials such as carbon fiber and carbon nanotube are preferably used. Particularly preferred is conductive carbon black.

  The proportion of the conductive auxiliary agent (C) is preferably 40 to 99% by weight, more preferably 50 to 95% by weight, and particularly preferably 60 to 90% by weight of the entire electrode forming material. It is because there exists a tendency for it to be inferior to an electrode moldability when there are too many conductive support agents, and when there is too little, it exists in the tendency for an electrical storage device with a high capacity density to be not obtained.

[Binder (D)]
Examples of the binder (D) include polymer materials such as chain polymers such as polyethylene glycol and polypropylene glycol, comb polymers such as polyphosphazene, polytetrafluoroethylene, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene. Examples thereof include copolymers, polyacrylonitrile, polymethyl (meth) acrylate, and styrene-butadiene rubber. Further, poly (meth) acrylate having an oxyethylene or oxypropylene group in the side chain, acrylonitrile, (meth) acrylic acid having oxyethylene or oxypropylene in the side chain, and the like are also included. These may be used alone or in combination of two or more.

  The ratio of the binder (D) is preferably 1 to 40% by weight of the entire electrode forming material, more preferably 1 to 30% by weight, and still more preferably 2 to 20% by weight. This is because if the amount of the binder is too large, an electricity storage device having a high capacity density tends not to be obtained, and if the amount is too small, the electrode formability tends to be inferior.

  In addition, when mix | blending electrolyte salt with the electrode formation material (material of the electrode layer 7) in this invention, the electrolyte salt shown in the postscript can use the electrolyte salt and the solvent which dissolves it.

  An electrode is manufactured using the above electrode forming material. Examples of the electrode manufacturing method include a method of mixing and compression molding the electrode forming material, a method of applying a solvent to the electrode forming material, and the like. Specifically, as the former, first, an electrode forming material containing at least (A) to (D) is mixed in a mortar, and then an electrode is formed on a current collector with a compression molding machine. . Examples of the compression molding machine include a lock molding machine and a jack molding machine. As the latter method, the above electrode forming material is added to water and sufficiently dispersed to prepare a paste. After applying this paste on the current collector, the water is evaporated to form a paste on the current collector. There is a method of forming a sheet electrode as a composite of a uniform mixture of active materials and the like.

  The porosity of the electrode of the present invention is preferably 20 to 90% by volume, particularly preferably 30 to 80% by volume, and further preferably 40 to 70% by volume. When the porosity is too small, the energy density tends to decrease, and when the porosity is too large, the dispersibility of the conductive auxiliary agent and the binder tends to deteriorate.

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

  In the present invention, the apparent volume of the electrode refers to “electrode area of electrode × electrode thickness”. Specifically, the volume of the electrode substance, the volume of the voids in the electrode, and the space of the uneven portions on the electrode surface The total volume of In addition, the true volume of the electrode refers to the “volume of the electrode constituent material”. Specifically, the average weight of the entire electrode constituent material is determined by using the constituent weight ratio of the electrode constituent material and the true density of each constituent material. The density can be calculated and calculated by dividing the total weight of the electrode constituent materials by this average density.

  The thickness of the positive electrode of the present invention is preferably 1 to 2000 μm, more preferably 10 to 1000 μm, and particularly preferably 100 to 900 μm. The thickness of the positive electrode is, for example, a dial whose tip shape is a flat plate having a diameter of 5 mm It can be calculated by measuring using a gauge (manufactured by Ozaki Mfg. Co., Ltd.) and obtaining the average of 10 measured values with respect to the surface of the electrode. In addition, when the positive 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, and the average of the measured values is obtained. From this value, the current collector is obtained. The thickness of the positive electrode is determined by subtracting the thickness of the positive electrode.

<About electricity storage devices>
Here, FIG. 2 shows an example of the electricity storage device of the present invention, and the electricity storage device has an electrolyte layer 3 and a positive electrode 2 and a negative electrode 4 provided to face each other with the electrolyte layer 3 interposed therebetween. Note that 1 is a current collector (for positive electrode), and 5 is a current collector (for negative electrode). FIG. 2 schematically shows the structure of the electricity storage device, and the thickness of each layer is different from the actual one.

  The electrode in the present invention shown in FIG. 1 can be used for a positive electrode (a laminate of the positive electrode 2 and its current collector 1 in FIG. 2) or a negative electrode (a laminate of the negative electrode 4 and its current collector 5 in FIG. 2). ) Can also be used. In particular, when the electrode of the present invention shown in FIG. 1 is used as a positive electrode and an electrode containing at least one selected from a compound capable of inserting and releasing ions and a metal is used as a negative electrode, the resulting electricity storage device has a higher capacity. Density and high energy density can be realized.

  As the positive and negative electrode current collectors (1, 5 in FIG. 2), metal foil or mesh such as carbon paper, carbon non-woven fabric, carbon cloth, nickel, aluminum, stainless steel, and copper is appropriately used.

  Moreover, although the said electrolyte layer 3 is comprised with electrolyte, the sheet | seat which makes a separator impregnate electrolyte solution and the sheet | seat which consists of solid electrolytes are used preferably, for example. The sheet made of the solid electrolyte itself also serves as a separator. In addition, since the electrode of the present invention also suppresses dissolution of the electrode active material in the electrolyte solution due to repeated charge and discharge, it is not limited to the solid electrolyte sheet or the electrolyte-impregnated sheet as described above, and the electrolyte solution is used as it is. Also good.

As described above, when the electrolytic solution is used as it is or when the separator is impregnated with the electrolytic solution and the electrode is also impregnated, the electrolyte constituting the electrolytic solution may be, for example, a metal ion such as lithium ion and an appropriate one for this Counter ions such as sulfonate ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, hexafluoroarsenic ion, bis (trifluoromethanesulfonyl) imide ion, bis (pentafluoroethanesulfonyl) imide ion, halogen A combination of ions and the like is preferably used. Specific examples of such an electrolyte 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, and the like. can give.

  Moreover, as a solvent which comprises the said electrolyte solution, at least 1 sort (s) of nonaqueous solvents, such as carbonates, nitriles, amides, ethers, ie, an organic solvent, are 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, dioxolane, dimethoxyethane, diethoxyethane, and γ-butyrolactone.

  Further, when the separator is used as described above in the electricity storage device of the present invention, the separator can prevent an electrical short circuit between the positive electrode and the negative electrode arranged opposite to each other, Any insulating porous sheet that is electrochemically stable, has a large ion permeability, and has a certain degree of mechanical strength may be used. As a material for the separator, for example, a porous porous sheet made of a resin such as paper, nonwoven fabric, polypropylene, polyethylene, or polyimide is preferably used. These may be used alone or in combination of two or more.

  By the way, as described above, when an electrode including at least one selected from a compound capable of inserting and releasing ions and a metal is used for the negative electrode, specifically, lithium metal or lithium ions during oxidation / reduction are used. Carbon materials, transition metal oxides, silicon, tin and the like that can be inserted and removed are preferably used. In addition, in the present invention, “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. Is used at less than 50% by weight of the forming material.

  The electricity storage device of the present invention is formed in various shapes such as a laminate cell, a porous sheet type, a sheet type, a square type, a cylindrical type, and a button type.

  In addition, it is preferable to assemble the said electrical storage device in inert gas atmosphere, such as an ultra-high purity argon gas, in a glove box.

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

  First, prior to Examples and Comparative Examples, each polymer was produced according to Production Examples 1 and 2 below.

[Production Example 1: Production of conductive polyaniline powder using tetrafluoroboric acid as a dopant]
As a conductive polymer (A) which is an electrode active material, a conductive polythiophene powder using tetrafluoroboric acid as a dopant was prepared as follows.

(Conductive polyaniline powder)
To a glass beaker having a capacity of 138 g of ion-exchanged water, 84.0 g (0.402 mol) of a 42 wt% tetrafluoroboric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd., special grade) was added, and a magnetic stirrer was used. While stirring, 10.0 g (0.107 mol) of aniline was added thereto. When aniline was first added to an aqueous tetrafluoroboric acid solution, the aniline was dispersed as oily droplets in the aqueous tetrafluoroboric acid solution, but then dissolved in water within a few minutes, resulting in a uniform and transparent aniline. It became an aqueous solution. 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., 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 ° C. Not to exceed. 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. Thereafter, using a Buchner funnel and a suction bottle, the obtained solid was No. Suction filtration was performed with two filter papers (manufactured by ADVANTEC) to obtain a powder. This powder was stirred and washed in a tetrafluoroboric acid aqueous solution of about 2 mol / dm ³ using a magnetic stirrer, then 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 (oxidized polyaniline) having tetrafluoroborate anion as a dopant as a bright green 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 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.

(Preparation of dedope conductive polyaniline powder)
The conductive polyaniline powder in the doped state thus obtained was put into a 2 mol / L sodium hydroxide aqueous solution and stirred in a 3 L separable flask for 30 minutes to neutralize the conductive polyaniline. Thereby, the tetrafluoroboric acid which is a dopant was dedope from polyaniline.

  The dedoped polyaniline was washed with water until the filtrate became neutral, then stirred and washed in acetone, and then filtered under reduced pressure using a Buchner funnel and a suction bottle. A polyaniline powder undopeped on 2 filter paper (manufactured by ADVANTEC) was obtained. This was vacuum-dried at room temperature (25 ° C.) for 10 hours to obtain dedoped polyaniline as a brown powder.

  Next, the dedope polyaniline powder thus obtained was placed 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 is washed with methanol and then with acetone, filtered, and then vacuum-dried at room temperature to obtain a reduced dedope polyaniline (reduced polyaniline). It was. In addition, the median diameter of the particles by light scattering method using acetone as a solvent was 13 μm.

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 5.8 × 10 ⁻³ S / cm.

  That is, this polyaniline has a higher electrical conductivity in an oxidized state in which ions are inserted than in a reduced state in which ions are eliminated. Therefore, this polyaniline is an electrode active material whose conductivity is changed by insertion / extraction of ions.

[Production Example 2: Preparation of conductive polythiophene powder using iron trichloride as a dopant]
As a conductive polymer (A) that is an electrode active material, a conductive polythiophene powder using iron trichloride as a dopant was prepared as follows.

(Conductive polythiophene powder)
Under a nitrogen atmosphere, 28.8 g of iron trichloride was added to 100 ml of chloroform in a three-necked flask. Thereafter, the flask was immersed in an ice bath containing sodium chloride and kept at 0 ° C. or lower. Thiophene (5.0 g) was dissolved in chloroform (50 g) and dropped into the iron trichloride and chloroform over 2 hours. After completion of dropping, the mixture was stirred at room temperature for 12 hours.

  The reaction solution was filtered, developed in methanol with stirring, and then filtered again. After repeating this operation 5 times, the obtained polythiophene powder was vacuum-dried overnight at room temperature. The obtained polythiophene powder was brown and the yield was 6.3 g.

(Conductivity of conductive polythiophene powder)
After pulverizing 150 mg of the conductive polythiophene 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 polythiophene powder disk having a thickness of 720 μm. A shaped molded body was obtained. The conductivity of the molded film measured by the 4-terminal method conductivity measurement by the Van der Pau method was 10.8 S / cm.

(Reductive dedoped polythiophene powder)
The polythiophene powder fraction was then stirred overnight in an aqueous solution containing 6 equivalents of hydrazine monohydrate of polythiophene monomer units. The reaction solution was filtered, developed in methanol with stirring, and then filtered again. After repeating this operation four times, the solid content was vacuum dried overnight at room temperature. The obtained polythiophene powder was reddish brown and the yield was 4.9 g.

(Conductivity of reduced and undoped polythiophene powder)
After pulverizing 150 mg of the above polythiophene powder in a reduced dedope state in a smoked mortar, vacuum reduction 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 disk-shaped molded film of polythiophene powder in a state was obtained. The conductivity of the molded film measured by the 4-terminal conductivity measurement by the Van der Pau method was 5.8 × 10 ⁻² S / cm.

[Production Example 3: Production of disulfide polymer (B)]
As the disulfide polymer, a compound represented by the following formula (3) was prepared. In addition, this compound can be manufactured based on Example 5 of Unexamined-Japanese-Patent No. 2012-229329, for example.

[Example 1: Combined use of polyaniline and disulfide polymer]
20 mg of the polyaniline produced in Production Example 1, 80 mg of the disulfide polymer produced in Production Example 3, 800 mg of acetylene black and 100 mg of polytetrafluoroethylene were mixed and kneaded using a smoked mortar.

  100 mg of the obtained kneaded material was placed on an aluminum mesh having a diameter of 12.5 mm, and compressed for 5 minutes at a pressure of 7 kN while vacuum degassing using a tablet molding machine (manufactured by Shimadzu Corporation). The electrode sheet thus obtained was vacuum dried at 60 ° C. for 3 hours.

(Production of electricity storage device)
An electricity storage device (cell) using the electrode sheet obtained as described above as a positive electrode was assembled as follows. That is, first, the electrode sheet prepared above was prepared as a positive electrode, coin-type metallic lithium (Honjo Metal Co., Ltd.) was prepared as a negative electrode, and a nonwoven fabric (TF40-50) manufactured by Hosen Co. was prepared as a separator. Next, a 1 mol / L lithium tetrafluoroborate propylene carbonate solution and ethylene carbonate were mixed at a volume ratio of 1: 1 to prepare an electrolytic solution.

  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 and a negative electrode are placed facing each other in a stainless steel HS cell (made by Hosen Co., Ltd.) for non-aqueous electrolyte secondary battery experiments, and the separator is positioned so that they do not short-circuit. The liquid was injected. And after injection | pouring of electrolyte solution, the HS cell was sealed and the cell was completed.

The said cell was left still in a 25 degreeC thermostat, and it measured in the constant current-constant voltage charge / constant current discharge mode using the battery charging / discharging apparatus (the Hokuto Denko company make, SD8). The end-of-charge voltage is 3.8 V. After the voltage reaches 3.8 V by constant current charging, constant voltage charging at 3.8 V is performed for 2 minutes, and then constant current discharge is performed up to a discharge end voltage of 1.5 V. went. The capacity density of the active material was 147 Ah / kg, the total capacity (Ah) was calculated from the amount of active material contained in the electrode unit area, and the rate at which this capacity was charged in 1 hour was defined as 1 C charge / discharge. And when 0.2 C charge / discharge was performed once, the capacity density of the said cell was 517 Ah / kg, the energy density was 1118 Wh / kg, and the average discharge voltage was 2.16V.
The capacity density and the energy density represent values converted per net weight of the positive electrode active material.

[Example 2]
20 mg of the polythiophene produced in Production Example 2, 80 mg of the disulfide polymer produced in Production Example 3, 800 mg of acetylene black and 100 mg of polytetrafluoroethylene were mixed and kneaded using a smoked mortar.

  100 mg of the obtained kneaded material was placed on an aluminum mesh having a diameter of 12.5 mm, and compressed using a tablet molding machine (manufactured by Shimadzu Corporation) at a pressure of 7 kN for 5 minutes while vacuum degassing. The electrode thus obtained was vacuum-dried at 60 ° C. for 3 hours.

(Production of electricity storage device)
In the same manner as in Example 1, a power storage device (cell) was produced and evaluated. In the above cell, the weight capacity density of the active material is 147 Ah / kg, the total capacity (Ah) is calculated from the amount of active material contained in the electrode unit area, and the rate of charging this capacity in 1 hour is 1C charge / discharge. It was. And when 0.2 C charge / discharge was performed once, the weight capacity density of the said cell was 433 Ah / kg, and the weight energy density was 1062 Wh / kg.

[Comparative Example 1: Disulfide polymer alone system]
100 mg of the disulfide polymer produced in Production Example 3, 800 mg of acetylene black and 100 mg of polytetrafluoroethylene were mixed and kneaded using a smoked mortar. Thereafter, electrodes and cells were produced in the same manner as in Example 1, and battery evaluation was performed.

  In the cell, the capacity density of the active material is 147 Ah / kg, the total capacity (Ah) is calculated from the amount of active material contained in the electrode unit area, and the rate of charging this capacity in 1 hour is defined as 1 C charge / discharge. did. And when 0.2 C charge / discharge was performed once, the capacity density of the said cell was 532 Ah / kg, the energy density was 957 Wh / kg, and the average discharge voltage was 1.80V.

[Comparative Example 2: Polyaniline alone system]
100 mg of polyaniline, 800 mg of acetylene black and 100 mg of polytetrafluoroethylene were mixed and kneaded using a smoked mortar.
Thereafter, electrodes and cells were produced in the same manner as in Example 1, and battery evaluation was performed.

  In the cell, the capacity density of the active material is 147 Ah / kg, the total capacity (Ah) is calculated from the amount of active material contained in the electrode unit area, and the rate of charging this capacity in 1 hour is defined as 1 C charge / discharge. did. And when 0.2 C charge / discharge was performed once, the capacity density of the said cell was 172 Ah / kg, the energy density was 533 Wh / kg, and the average discharge voltage was 3.10V.

  From the above, the Example product has a high discharge voltage and a high capacity density and a high energy density, whereas the Comparative Example 1 product has a low discharge voltage, and the Comparative Example 2 product has a low capacity density and energy density. there were.

  The electricity storage device using the electrode of the present invention can be suitably used as an electricity storage device such as a lithium secondary battery or a high capacity capacitor. The power storage device can be used for the same applications as conventional secondary batteries and electric double layer capacitors. For example, portable electronic devices such as portable PCs, cellular phones, and personal digital assistants (PDAs), and hybrid electric devices. Widely used in power sources for driving automobiles, electric vehicles, fuel cell vehicles and the like.

6 Current collector 7 Electrode layer

Claims (5)

An electrode comprising an electrode layer on at least a part of a current collector surface, wherein the electrode layer includes the following (A) to (D).
(A) Conductive polymer.
(B) Disulfide polymer.
(C) Conductive aid.
(D) Binder. The electrode according to claim 1, wherein the disulfide polymer (B) is a compound having a structure represented by the following formula (1).
(—S—X—S—S—Y—S—) _n (1)
[In the above formula (1), X and Y each represents an organic group, which may be the same or different from each other. N represents a positive natural number. ]   The electrode according to claim 1 or 2, wherein the disulfide polymer (B) has a weight average molecular weight of 5,000 to 100,000.   The electrode according to any one of claims 1 to 3, wherein the conductive polymer (A) is at least one selected from the group consisting of polyaniline, polyaniline derivatives, polypyrrole, polypyrrole derivatives, polythiophene and polythiophene derivatives.   It is an electrical storage device which has an electrolyte layer and the positive electrode and negative electrode which were provided facing this on both sides, Comprising: A positive electrode is an electrode as described in any one of Claims 1-4, and a negative electrode inserts ion -An electrical storage device comprising at least one selected from the group consisting of a detachable compound and a metal.

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