JP3079291B2 - Electrochemically active electrode and electrochemical cell using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochemically active electrode using a composite of polyaniline and a polymer having a sulfonic acid group as an active substance, and an electrochemical cell using the same.

[0002]

2. Description of the Related Art In recent years, polyacetylene, polypyrrole and the like have been expected to be applied to conductive materials, secondary batteries, and electrode materials such as electrochromic displays (ECD), and polyaniline has been attracting attention as one of the materials. . It is known that the above-mentioned polyaniline is synthesized by oxidizing aniline. Examples of the production method include a chemical oxidative polymerization method using an oxidizing power of a peroxide, a metal ion or a metal complex compound, and an acidic aqueous solution. There is known a method in which aniline is subjected to electrolytic oxidation polymerization. JP-A-59-98165 discloses doping a polymer having a sulfonic acid group such as polystyrene sulfonic acid or polyvinyl sulfonic acid into polyaniline, and dedoping a polyaniline obtained by polymerization. To obtain a water-soluble conductive polymer by doping with an acid is disclosed in
No. 4,767,464. Furthermore, a battery in which a polymer sulfonic acid-polyaniline composite obtained by polymerizing aniline in a polymer molded article and a solid electrolyte is used as a high molecular weight dopant, for example, using a polymer sulfonic acid is disclosed in No. 174076.

[0003]

However, conventional polyaniline doped with low molecular weight anions or polyaniline containing no dopant is used in secondary batteries or ECDs.
When used for the electrode, a part of the polyaniline is dissolved in the organic solvent with charge and discharge, so the soluble component reacts at the counter electrode,
It was feared that adverse effects such as an increase in self-discharge of the battery or a shortened life would be caused. It is necessary to wash with an organic solvent to reduce the soluble components, which is industrially disadvantageous. Further, in the case where the composite of the polymer sulfonic acid-polyaniline composite and the solid electrolyte is used for an electrode of a secondary battery, there is a problem that the charge / discharge capacity is not sufficiently high. Furthermore, the battery capacity, elution into the electrolytic solution, and swelling in the case of using a composite of polyaniline doped with a polymer sulfonic acid as an electrode were not known at all.

According to the studies made by the present inventors, in the case where powdered polyaniline is compression-molded into an electrode, if swelling when immersed in an electrolytic solution is suppressed, the charge-discharge characteristics tend to deteriorate. It was difficult to obtain a polyaniline electrode having excellent swelling and low swelling. The present invention has been made in view of the above situation, and it is possible to obtain good charge / discharge characteristics while preventing both elution of polyaniline and swelling of the electrode. It is an object of the present invention to provide a simple electrode and an electrochemical cell using the same as a positive electrode.

[0005]

Means for Solving the Problems The present inventors have continued research on an electrochemical cell using a polyaniline-based compound for the positive electrode. As a result, it was found that doping polyaniline with an appropriate amount of a polymer sulfonic acid reduced the elution of polyaniline into an organic solvent and reduced the swelling of the electrode, and showed good charge-discharge characteristics, and completed the present invention. . That is, in the present invention, a polymer sulfonic acid is doped into undoped polyaniline, and the molar ratio (N / S) of the nitrogen atom (N) of the polyaniline to the sulfur atom (S) of the sulfonic acid group in the polymer is 2. The present invention provides an electrochemically active electrode characterized by satisfying ≦ N / S ≦ 40, and an electrochemical cell comprising the same as a positive electrode, a non-aqueous electrolyte and a negative electrode.

Hereinafter, a method for manufacturing an electrode according to the present invention will be described in detail. As a method for synthesizing polyaniline used in the present invention, a method of oxidative polymerization with an oxidizing agent (hereinafter, referred to as a chemical oxidative polymerization method) and a method of electrochemical oxidative polymerization (hereinafter, referred to as an electrolytic oxidative polymerization method). ) Can be used.

In the chemical oxidative polymerization method, polyaniline is synthesized by mixing an acidic solution of aniline and an oxidizing agent. At this time, a standard hydrogen electrode (NH
It is desirable to use one having an oxidation-reduction potential of 0.6 V or more and 2.5 V or less with respect to E). This is because aniline does not polymerize at a voltage of 0.6 V or less, while aniline is decomposed at a voltage of more than 2.5 V. On the other hand, within the above range, polyaniline having a good polymerization yield and good characteristics can be obtained.

[0008] Examples of the oxidizing agent include ferric salt, persulfate, hydrogen peroxide and dichromate. Specifically, the ferric salts include ferric perchlorate, ferric periodate, ferric borofluoride, and ferric hexafluorophosphate.
There are iron, ferric sulfate, ferric nitrate, ferric chloride and the like. Examples of the persulfate include ammonium persulfate, sodium persulfate, potassium persulfate, and the like, and examples of the dichromate include potassium dichromate, sodium dichromate, and the like. Absent. However,
Among these oxidizing agents, ferric perchlorate, ferric periodate, ferric borofluoride, and ferric hexafluorophosphate
Iron, ammonium persulfate and hydrogen peroxide are particularly preferred as they give good results. Further, these oxidizing agents may be used alone or in combination of two or more.

If the amount of the oxidizing agent used is too large, it is useless. If the amount is too small, polyaniline having a high degree of polymerization cannot be obtained. 0.1 to 2 times, more preferably 0.5 to 2 times.
２2 times is particularly preferred. When the above-mentioned oxidizing agent other than hydrogen peroxide is used, the anion of the oxidizing agent or the anion generated after the oxidation reaction is taken into the polyaniline, but there is no particular problem since it is exchanged with the polymer anion later. In the chemical oxidation polymerization, the polymerization may be performed in the presence of a conductive filler. Examples of the filler to be used include a carbon material such as graphite powder, carbon black, and carbon fiber, an inert metal powder, and a metal fiber.

In the electrolytic oxidation polymerization method, an acid stable under electrolytic conditions is used.
Of polyaniline by electrolytic polymerization of aniline in the presence of
I do. In this case, using an acidic aqueous solution of aniline,
Various methods can be used as the method for chemical polymerization.
You. Specifically, constant current method, constant potential method, constant voltage method, potential
Scanning method and potential step method can be mentioned.
Use constant current method and constant potential method to control the amount of electricity
Is preferred. Current density in electrolytic oxidation polymerization
It varies depending on the concentration of niline, acid and polymerization temperature.
0.001-500mA / cm^Two Perform within the range. So
In the range of 0.001 to 50 mA / cm ^Two Is preferred
And more preferably 0.1 to 50 mA / cm^Two Range of
Particularly preferred. In the constant potential method and constant voltage method, the current density is
You only have to select the conditions so that they fall within the range. For example, the potentiostatic method
0.8 to 10 V is preferable for the silver chloride reference electrode.
And 0.8 to 2 V is particularly preferable.

As the acid used in both polymerization methods, any acid can be used as long as it is stable under chemical oxidation polymerization or electrolytic oxidation polymerization of aniline, forms a salt with aniline, and dissolves aniline in an aqueous solution. Good. Specifically, perchloric acid, borofluoric acid, hexafluorophosphoric acid, periodic acid, sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid,
Methanesulfonic acid and the like are exemplified, but perchloric acid, borofluoric acid, hexafluorophosphoric acid, and periodic acid are preferred because they give good results. Further, a polymer sulfonic acid can also be used as an acid that forms a salt with aniline. Polystyrene sulfonic acid, polyvinyl sulfonic acid, poly (2
-Acrylamide-2-methylpropanesulfonic acid),
Examples include sulfonated polystyrene, sulfonated polyethylene, Nafion (manufactured by Aldrich), polyallylsulfonic acid, and the like. Since the solubility of the salt between the high molecular sulfonic acid and aniline is low, the acid used is preferably a low molecular acid. The concentration of these acids may be at least the equivalent of the aniline used, and is usually preferably 0.1 N or more.

The aniline concentration in the polymerization reaction is not particularly limited. Usually, the upper limit is the concentration that dissolves in the acidic solution. However, since aniline is oxidized and precipitated as polyaniline by the reaction, there is no particular problem since the aniline is dissolved during the reaction and the reaction proceeds even if the concentration is higher than the dissolution concentration. On the other hand, the lower limit is not particularly limited, but it is generally preferable to use 0.1 mol / l or more, since it is not efficient at a very low concentration. The purity of the aniline used is not particularly limited, but is preferably 95% or more.

The reaction may be carried out by stirring an acidic solution containing aniline or a solution containing a slurry of aniline salt with the oxidizing agent as it is in the chemical polymerization method, or by adding a solution containing the oxidizing agent and stirring it. The above solution may be charged into an electrolytic cell having a pair of electrodes for electrolysis. The reaction temperature and reaction time are not particularly limited, but the reaction is usually carried out at a temperature between the freezing point and the boiling point of the solution containing aniline. In order to obtain polyaniline having excellent charge / discharge characteristics, the reaction is preferably performed at 50 ° C. or lower, more preferably at 40 ° C. or lower. The reaction time is not particularly limited and can be appropriately determined in consideration of the oxidizing agent to be used and the amount of current supplied, but is generally in the range of 5 minutes to 100 hours, and more preferably in the range of 10 minutes to 50 hours.

The polyaniline obtained by polymerization is in a state in which an anion derived from an oxidizing agent or an acid used in the reaction is doped (in a state in which the anion is incorporated). It is necessary to dope. As a method of removing the anion, a method of contacting the polyaniline with an alkaline compound that does not react with the polyaniline skeleton can be adopted. The alkali used at this time is not particularly limited as long as the pH becomes 11 or more after charging the polyaniline obtained by polymerization, and examples thereof include sodium hydroxide, potassium hydroxide, lithium hydroxide, and aqueous ammonia. is there.

The polyaniline may be formed into a film or a fibrous form instead of a powder, but in this case, it is preferable to form the polyaniline before doping with a polymer sulfonic acid because a higher strength film or fiber can be obtained. . Examples of the method of molding include a method of compacting by applying pressure, a method of dissolving in a solvent once, and a method of molding in a process of volatilizing the solvent.

The solvent used for dissolving polyaniline is not particularly limited as long as it can sufficiently dissolve boraniline, and specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, and dimethyl. Sulfoxide, N-methyl-2-pyrrolidone, 1,3
-Dimethyl-2-imidazolidinone and the like, examples of which include N, N-dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-
2-imidazolidinones are preferred. When forming into a film, the method is not particularly limited. For example, a method of applying to a substrate insoluble in a solvent using a polyaniline solution, a spin coating method, a casting method, a dipping method, a bar coating method, a roll coating method, and the like are employed. It is preferable to use a current collector as the base material because the current collector can be used as it is.

As a method for obtaining a composite of polyaniline and a polymer sulfonic acid as an electrode material, a method of dedoping polyaniline and then doping with a polymer sulfonic acid to form a composite is used. This method is preferable because it eliminates the need to remove unreacted monomers and provides a composite exhibiting good charge / discharge characteristics.

Regarding the concentration of the polymer sulfonic acid in the polyaniline / polymer sulfonic acid complex, when the content ratio of nitrogen (N) and sulfur (S) is in the range of 2 ≦ N / S ≦ 40, the elution of polyaniline is small, In addition, a composite exhibiting good charge / discharge characteristics can be obtained. When 2 ≦ N / S ≦ 25, the dissolution of polyaniline is small and the swelling is small, so that it is preferable.
Those in the range of 2 ≦ N / S ≦ 16 are more preferable because they show excellent characteristics comprehensively. When the N / S exceeds 40, the charge / discharge capacity per weight is high, but both elution and swelling are large, and the characteristics of the electrode are low. Further, the charge / discharge capacity per volume is low due to swelling of the electrode. on the other hand,
If N / S is smaller than 2, a large amount of the polymer sulfonic acid does not participate in the electrode reaction, and the charge / discharge capacity per weight of the positive electrode becomes extremely small. Or not.

Hereinafter, a method for obtaining a polyaniline-polymer sulfonic acid complex will be described more specifically. As a method for doping the undoped polyaniline with the polymer sulfonic acid, a method of doping the polymer sulfonic acid solution by introducing the polyaniline into the polymer sulfonic acid solution is preferable.

As the polymer sulfonic acid used here,
Reacts easily with polyaniline and in a practical time 2 ≦ N
There is no particular limitation as long as it can be doped in the range of / S ≦ 40. Specific examples include polystyrenesulfonic acid, polyvinylsulfonic acid, poly (2-acrylamido-2-methylpropanesulfonic acid), sulfonated polystyrene, sulfonated polyethylene, Nafion (manufactured by Aldrich), polyallylsulfonic acid, and the like. But especially
Polystyrene sulfonic acid is preferred.

As a solvent for dissolving the polymer sulfonic acid, any solvent can be used as long as it can be dissolved in a sufficient concentration and can be doped into polyaniline. Examples of the solvent include water and lower alcohols. Water is particularly preferred. The concentration of the polymer sulfonic acid solution is not particularly limited, but if it is too dilute, N / S ≦
Since it cannot be doped to 40, or it takes too long to dope and is not practical, it is usually 0.1
It may be used more than specified. When the treatment is performed using a high-concentration polymer sulfonic acid solution, N / S <2 may be satisfied. However, by repeating washing with a solvent that dissolves the polymer sulfonic acid, 2 ≦ N / S can be easily achieved. It can be adjusted in the range of ≦ 40.

The composite of polyaniline and high molecular sulfonic acid obtained by the above method needs to be sufficiently dried to remove the solvent before being incorporated into an electrode, and then formed into an electrode. Drying is generally performed by heating under an inert atmosphere, and examples thereof include vacuum drying and heating in a nitrogen gas.
The drying temperature used depends on the solvent and the drying method. However, below room temperature, the solvent is not sufficiently evaporated, and at a high temperature exceeding 400 ° C., polyaniline is decomposed. Therefore, the drying temperature is 25 ° C to 400 ° C, preferably 40 to 250 ° C,
More preferably, it may be appropriately selected within a range of 40 ° C to 130 ° C.

When the composite of polyaniline and polymer sulfonic acid obtained as described above is used as an electrode,
In the case of a film or a fiber, it may be arranged so as to be in close contact with the current collector according to the shape of the cell. In the case of powder, it is necessary to mold according to the cell shape. For example,
It can be used as a disk-shaped or sheet-shaped molded body by pressure molding. At that time, a conductive filler for supplementing conductivity and a binder for supplementing moldability may be mixed.

The electrode obtained according to the present invention has a positive electrode
Combined with the non-aqueous electrolyte and the negative electrode
It can be an electrochemical cell such as a battery or ECD.
In particular, it can be suitably used as a positive electrode of a secondary battery.
The non-aqueous electrolyte that composes these cells is polyanilyte.
When a complex of sulfonic acid and polymer sulfonic acid is discharged,
Cations that can bind to the
Salts containing anions that can be doped into lianiline
Dissolved in a medium capable of electrochemical migration of ions
Can be used. Specific examples of electrolyte salts
Is LiPF₆ , LiSbF₆ , LiAsF₆, LiC
10_Four, LiBF_Four, NaI, NaPF₆ , NaSbF
₆ , NaAsF ₆ , NaClO_Four, NaBF_Four, KI,
KPF₆ , KSbF₆ , KAsF₆ , KCLO_Four, KB
F_FourEtc. And these electrolytes are used alone
Or two or more kinds may be used in combination.

The electrolyte medium does not need to be a liquid as long as the ions of the salt can electrochemically move in the medium, and a solid electrolyte such as an inorganic or organic solid electrolyte can be used. Practically, in order to make full use of the properties of the composite, a liquid is preferred. As a medium for such an electrolyte, a non-aqueous solvent, that is, an organic solvent can be used, and there is no particular limitation as long as it does not substantially cause a chemical reaction with the electrode. As the organic solvent, an aprotic organic solvent having a high dielectric constant is preferable. Specifically, propylene carbonate, tetrahydrofuran,
1,2-dimethoxyethane, sulfolane, 8-methylsulfolane, dichloromethane, γ-butyrolactone, dimethylsulfoxide, dimethylformamide, dioxolan, acetonitrile, benzonitrile, nitromethane,
Examples include dimethylacetamide, but are not limited thereto. These organic solvents may be used alone or as a mixture of two or more.

The electrolyte concentration in the electrolyte is not particularly limited.
It can be appropriately determined in consideration of the type of the electrolyte to be used and the type of the solvent. However, usually the range is preferably 0.001 to 10 mol / l, more preferably 0.01 to 2 mol / l.

In the case of a chemical electric cell having the electrode of the present invention as a positive electrode, the counter electrode, ie, the negative electrode, is Li,
Metals such as Na, K, Mg, Ca, Pb, Zn, Al and alloys thereof, polyacetylene, polyparaphenylene,
Examples include conductive polymer compounds such as polyparaphenylenevinylene and derivatives thereof, and carbon-based materials such as carbon fiber and graphite, but are not necessarily limited thereto. When the electrode of the present invention was used for an ECD, a transparent or translucent material such as ITO or Nesa glass was used as a current collector, and a solution of undoped polyaniline was applied thereon, and the solvent was volatilized. Thereafter, a method of preparing a polyaniline-polymer sulfonic acid composite electrode by a method of doping with a polymer sulfonic acid is generally used. In this case, the counter electrode may be made of ITO or Nesa glass, or the above-mentioned metal or the like. The configuration of the electrochemical cell (positive electrode / non-aqueous electrolyte / negative electrode) in which the electrode of the present invention can be used is as follows:
Polyaniline-polymer sulfonic acid complex / non-aqueous electrolyte /
Conductive polymer (cation doping), polyaniline-
Examples include polymer sulfonic acid complex / alkali metal salt electrolyte / alkali metal or aluminum-alkali metal alloy, polyaniline-polymer sulfonic acid complex / non-aqueous electrolyte / carbon-based material (cation doping), It is not necessarily limited to these.

Although the reason why the elution and swelling of the electrode comprising the polyaniline-polymer sulfonic acid complex of the present invention is not necessarily clear, it is not clear that the polyaniline molecule and the polymer sulfonic acid molecule are entangled with each other or bonded at a plurality of positions. It is considered that this is due to cross-linking. Also,
The reason why a smaller amount of electrolyte solution is better than before is that polyaniline-
This is because the positive electrode composed of the polymer sulfonic acid complex performs doping of anions and release of cations during charging, and conversely, incorporation of cations and undoping of anions occurs during discharging, so that there is substantially no change in salt concentration. It is presumed.

[0029]

As described above, undoped polyaniline is doped with a polymer sulfonic acid, and the molar ratio (N) of nitrogen (N) of polyaniline to sulfur atom (S) of sulfonic acid group is changed.
/ S) By setting 2 ≦ N / S ≦ 40, both the elution of polyaniline and the swelling of the electrode are prevented, the amount of the electrolyte is significantly reduced, and good charge / discharge characteristics are exhibited. An electrochemical cell can be obtained.

[0030]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples.

Example 1 An electrode manufacturing method of the present invention is manufactured through the steps of synthesis and dedoping of polyaniline, neutralization and drying of polyaniline and a polymer sulfonic acid, and preparation or molding of an electrode. Hereinafter, description will be made in the order of steps.

(Synthesis and Dedoping of Polyaniline) First, 0.30 mol of aniline was dissolved in a 1N aqueous solution of perchloric acid (600 ml). Next, 0.30 mol of ammonium persulfate was added to a 1 N aqueous solution of perchloric acid (400 m
The solution dissolved in 1) was slowly dropped into the above aqueous solution of perchloric acid, and allowed to react for 6 hours under ice-cooling. The resulting precipitate was filtered and washed with water. Next, the precipitate was added to a 1 N aqueous solution of lithium hydroxide to remove anions (dedoping treatment). Thereafter, washing with water and washing with methanol were sufficiently performed to remove unreacted lithium hydroxide. Thereafter, the treated polyaniline was placed in a vacuum drier and dried at 60 ° C. for 19.5 hours.
A powdered polyaniline was obtained. The weight of the obtained polyaniline was 77.1% based on the raw material aniline.

(Neutralization and Drying of Polyaniline and Polymeric Sulfonic Acid) 3.32 g of this powdered polyaniline was placed in a 1 N aqueous solution of polystyrenesulfonic acid (100 ml) having a sulfonic acid group concentration of 1 N, and stirred for 15 hours to neutralize. Processing was performed. After the treatment, the mixture was filtered, washed lightly with water, placed in a vacuum drier, dried at 60 ° C. for 6 hours, and then at 80 ° C. for 8 hours to obtain a polyaniline-polystyrene sulfonic acid composite.
00 g were obtained.

(Preparation of Electrode) 16.0% by weight of acetylene black was mixed with this composite, and 14.9 mg of the mixture was mixed.
Was pelletized using a tablet press for infrared spectroscopy. (Preparation of Secondary Battery for Evaluation) A secondary battery was formed by wrapping the pellets in a platinum net to form a positive electrode, a lithium foil as a negative electrode, and propylene carbonate (PC) containing 1 mol / l of LiBF ₄ as an electrolyte.

This secondary battery was placed in an argon atmosphere for 0.2
The battery was repeatedly charged and discharged from 4.0 V to 2.5 V with a constant current of 5 mA / cm ² , and showed a discharge capacity of 166 mAh / g based on the weight of polyaniline in the positive electrode. The swelling of the positive electrode after 13 days was as small as 1.19 times the volume ratio.

The polyaniline-polystyrene sulfonic acid composite used here was analyzed by elemental analysis to find that N / S = 2.68.
Met. Also, take 100 mg of this complex,
It was placed in a 5 ml PC and left standing for about 16 hours. Thereafter, the mixture was filtered, and the ultraviolet-visible absorption spectrum of the liquid portion was measured. The absorption of light was very small, and only an absorption peak having an absorbance of less than 0.1 (cell length of 10 mm) was observed at around 375 nm. It was confirmed that it was difficult.

Example 2 A polyaniline-polystyrene sulfonic acid composite was obtained in the same manner as in Example 1 except that the neutralization treatment using an aqueous solution of polystyrene sulfonic acid was performed for 2 hours. When a battery using this composite was charged and discharged in the same manner as in Example 1, the battery was 142 m2 based on the weight of polyaniline in the positive electrode.
It showed a discharge capacity of Ah / g. The swelling of the positive electrode after 7 days was as small as 1.20 times the volume ratio. When the polyaniline-polystyrene sulfonic acid composite used here was examined by the same method as in Example 1, N / S = 15.1, and the amount of elution to PC was less than 0.1 with an absorbance of less than 0.1. It was confirmed that.

Example 3 A polyaniline-polystyrene sulfonic acid composite was prepared in the same manner as in Example 1 except that a neutralization treatment was performed for 2 hours using an aqueous solution of polystyrene sulfonic acid having a sulfonic acid group concentration of 0.2 N. Obtained. When a battery using this composite was charged and discharged in the same manner as in Example 1, it showed a discharge capacity of 141 mAh / g based on the weight of polyaniline in the positive electrode. The swelling of the positive electrode after 7 days was 1.58 times the volume ratio. When the polyaniline-polystyrene sulfonic acid composite used here was examined by the same method as in Example 1, N / N
S = 39.2, and it was confirmed that the amount of elution to PC was less than 0.1 with an absorbance of less than 0.1.

Comparative Example 1 A polyaniline-polystyrene sulfonic acid composite was prepared in the same manner as in Example 1 except that a neutralization treatment was performed for 2 hours using an aqueous solution of polystyrene sulfonic acid having a sulfonic acid group concentration of 0.02 N. Obtained. When a battery using this composite was charged and discharged in the same manner as in Example 1, it showed a discharge capacity of 147 mAh / g based on the weight of polyaniline in the positive electrode. The swelling of the positive electrode after 7 days was 1.66 times the volume ratio. The polyaniline-polystyrene sulfonic acid composite used here was found to be N
/ S> 100, and the elution amount to PC was large at an absorbance of 0.2.

Comparative Example 2 A neutralization treatment was performed for 24 hours using an aqueous solution of polystyrene sulfonic acid having a sulfonic acid group concentration of 1 N, followed by filtration and drying under reduced pressure to obtain a polyaniline-polystyrene sulfonic acid composite. This polyaniline-polystyrene sulfonic acid composite was examined by the same method as in Example 1 and found to have N / S = 1.52. When a battery using this composite was produced in the same manner as in Example 1, the polyaniline electrode was very poor in moldability and collapsed into the electrolytic solution, so that it was impossible to substantially repeatedly charge and discharge. . The elution amount to PC was very low because the absorbance was less than 0.1.

Comparative Example 3 Perchloric acid-doped polyaniline was obtained in the same manner as in Example 1 except that the neutralization treatment was performed using a 1N aqueous solution of perchloric acid. When the battery using this polyaniline was charged and discharged in the same manner as in Example 1, it showed a discharge capacity of 145 mAh / g based on the weight of polyaniline in the positive electrode. The swelling of the positive electrode after 7 days was 2.5 times the volume ratio. Examination by the same method as in Example 1 revealed that the elution amount to PC was large at an absorbance of 0.3.

【The invention's effect】

As described above, when the electrode of the present invention is used in combination with an electrochemical cell such as a secondary battery, it prevents both elution of polyaniline from the electrode and swelling of the electrode.
Since a high charge / discharge capacity can be obtained, an excellent effect of obtaining a long-life, high-performance electrochemical cell such as a secondary battery is exhibited, and its industrial value is large.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahisa Fujimoto 2--18 Keihanhondori, Moriguchi City Sanyo Electric Co., Ltd. (72) Inventor Noriyuki Yoshinaga 2-18-18 Keihanhondori Moriguchi City Sanyo Electric Co., Ltd. (72) Inventor Kokazu Uemura 6, Kitahara, Tsukuba, Ibaraki Pref. Within Sumitomo Chemical Co., Ltd. (72) Inventor Toshihiro Onishi 6, Kitahara, Tsukuba, Ibaraki Pref., Sumitomo Chemical Co., Ltd. 6 Kitahara, Tsukuba, Japan Sumitomo Chemical Co., Ltd. (56) References JP-A-3-6223 (JP, A) JP-A-63-27526 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H01M 4/60 C08L 79/00 H01M 4/02-4/04 H01M 10/40 JICST file (JOIS)

Claims (3)

(57) [Claims] An undoped polyaniline obtained by doping a polymer sulfonic acid with a molar ratio (N / N) of a nitrogen atom (N) of the polyaniline and a sulfur atom (S) of a sulfonic acid group in the polymer. An electrochemically active electrode, wherein S) is 2 ≦ N / S ≦ 40. 2. An electrochemical cell comprising the electrode of claim 1 as a positive electrode, a non-aqueous electrolyte and a negative electrode. 3. A secondary battery comprising the electrode of claim 1 as a positive electrode, a non-aqueous electrolyte and a negative electrode.