JPH0636361B2 - Secondary battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a secondary battery using a conductive material having a conductive polymer on any surface of a specific base material as an electrode material. Is.

<Prior Art> In recent years, a secondary battery using a conductive polymer made of various organic materials as an electrode material has been proposed.

The conductive polymer used as the electrode material of this type of secondary battery is
Usually, the conductivity is low, but it is possible to dope and undope the dopants such as various anions and cations, and the dope treatment dramatically increases the conductivity. Then, a conductive polymer doped with anions is used as a positive electrode material, and a conductive polymer doped with cations is used as a negative electrode material, and a solution containing the above dopant is used as an electrolytic solution. A battery that can be charged and discharged is constructed by performing the chemical reversible process.

Polymers having a conjugated double bond in the main chain, such as polyacetylene, polyparaphenylene, polythienylene, polypyrrole, polyaniline, and polyparaphenylene vinylene, have been known as such conductive polymers, and polyacetylene is an example. In this case, polyacetylene is used as an electrode material for at least one of the positive electrode and the negative electrode, and anions such as BF ₄ ⁻ , ClO ₄ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , or Li ⁺ , Na ⁺ , R ₄ −N ⁺ ( R represents an alkyl group) and the like is electrochemically reversibly doped and undoped.

By the way, such a conductive polymer is obtained in the form of powder, granules, lumps or films. In the case of powder, powder or lumps of conductive polymer, these are used as an electrode material for the non-aqueous electrolyte solution. In the case of constituting a secondary battery or a solid electrolyte secondary battery, they may be used alone or after adding an appropriate conductive material for improving conductivity and / or a thermoplastic resin for increasing mechanical strength of electrodes. However, it takes time and effort to form an electrode by pressure forming into an electrode shape. In that respect, the conductive polymer film has a feature that the electrode can be prepared relatively easily because the electrode can be formed only by punching them out to the electrode size.

As the conductive polymer film as described above, a polyacetylene film obtained by blowing acetylene gas into a glass wall coated with a polymerization catalyst and then peeling the glass wall from the glass wall, or an electrochemical oxidation reaction (electrolytic oxidation polymerization)
Polyphenylene film or polypyrrole film obtained by peeling from this electrode after being formed on an electrolytic electrode, or a solution containing an oxidizing agent and a polymer binder is applied on a substrate such as PET film and vapor of pyrrole, aniline, etc. is applied. There is known a conductive composite film or the like obtained by contacting with each other to form a film-shaped conductive polymer layer on a substrate.

<Problems to be Solved by the Invention> However, when a secondary battery is constructed by using the above-mentioned conventional conductive polymer film as an electrode material of a battery, a polyacetylene film is present due to the presence of a trace amount of oxygen and moisture in the battery. Since the polymer deteriorates, the performance as an electrode deteriorates, and there is a drawback that the cycle life is significantly reduced due to a sudden increase in charging voltage and a decrease in charge / discharge efficiency during the cycle. There is a problem in that the electrode production work is difficult and complicated because it is easily oxidized, and the storage property of the electrode is poor because the property deterioration due to oxidation is large.

Further, in the polyphenylene film and the polypyrrole film produced by the electrochemical oxidative polymerization reaction, the size of the film is regulated by the size of the electrolytic electrode, and the manufacturing method is complicated and requires a specific manufacturing apparatus. This causes a high battery cost. Furthermore, since it is difficult to obtain a thick and uniform film, when this film is used in combination with a current collector as a battery electrode, contact with the current collector is deteriorated during charge / discharge cycles, and battery reaction does not occur. Since it is concentrated on a part of the electrode, there is a problem that the battery performance is easily deteriorated.

Further, in the case of the above-mentioned conductive composite film, since a polymer binder is used to hold an oxidizing agent on the substrate, the conductive polymer obtained after the polymerization reaction is a polymer of pyrrole or aniline and this polymer binder. It becomes a composite conductor mixed with. Therefore, the concentration of the polymer such as pyrrole and aniline having conductivity in the conductive polymer is reduced, when using this as a material for electrodes, for example, compared to when using the conventional conductive polymer film, Even if the same performance is tried to be exhibited, there is a problem in that the performance is inferior because of a reduction in the polymer concentration.

Therefore, the present inventors previously mentioned in Japanese Patent Application No. 60-225761 (Japanese Patent Laid-Open No. 62-84115) that a conjugated double bond was formed on a substrate having a space capable of holding the oxidizing agent in the presence of the oxidizing agent. A novel conductive material produced by vapor-phase polymerization of a compound having the above is produced in an arbitrary shape, particularly in the form of a film, without the above-mentioned drawbacks. Japanese Patent Application No. 60-260923 (JP-A-60-260923) 62-119860) proposed to use this conductive material as an electrode material for secondary batteries.

However, in the conductive material of the above-mentioned Japanese Patent Application No. 60-225761, when it is attempted to hold the oxidant on only one side of the substrate, for example, to form a conductive polymer layer on one side of the planar substrate, the oxidant is Since it penetrates into the entire space of the base material and is easily retained, the oxidant also penetrates to the other surface of the base material, and after the vapor phase polymerization, the conductive polymer is formed on the entire base material, resulting in only one surface of the base material. It has been found that it is very difficult to produce a conductive polymer in the.

Therefore, when the conductive material is used as at least one of the positive electrode and the negative electrode, as in the case where the conventional conductive polymer film is used as the electrode material, the both electrodes should not come into direct contact between the opposing electrodes. It is necessary to dispose a diaphragm (separator) such as a non-woven fabric or a current collector in close contact between the electrode and the battery can. There is a drawback in that it requires a step of carefully and closely bonding the electric body.

<Means for Solving Problems> The inventors of the present invention have conducted research to solve the above problems and found that a base material having a space capable of holding an oxidant and at least one surface of which is hydrophobic is an oxidizer. The compound having a conjugated double bond is polymerized on the base material in a gas phase atmosphere by treating the base material with the oxidant held on only one side of the base material, It has been found that the intended purpose can be achieved when the conductive material obtained by forming the polymer is used as at least one of the positive electrode and the negative electrode.

The oxidizing agent as described above is a compound having a polymerization activity for a compound having a conjugated double bond, and is used alone or
Used in combination with more than one type. Usually, a metal salt having a strong acid residue, halogen, or cyan, a peroxide, or the like is used. Specifically, Fe (ClO ₄ ) ₃ , Fe (BF ₄ ) ₃ , Fe ₂ (SiF ₆ ) ₃ , Cu (ClO ₄ ) ₂ , Cu (BF ₄ ) ₂ , CuSiF ₆ , FeCl ₃ , CuC
l ₂ , K ₃ [Fe (CN) ₆ ], RuCl ₃ , MoCl ₅ , WCl ₆ , (NH ₄ ) ₂ S ₂ O ₈ , K ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ , NaBO ₃ H ₂ O ₈ , etc., and those having crystal water or those obtained as an aqueous solution can also be used.

Further, as the above-mentioned base material, one having a space capable of holding the above-mentioned oxidizing agent and having at least one surface exhibiting hydrophobicity is used. Hydrophobicity has a contact angle of water of 90 ° or more. The oxidant is used as an aqueous solution so that it can be easily retained on only one side of the substrate. When an organic solvent such as methanol, ethanol, acetonitrile, or tetrahydrofuran that has permeability to the base material is used as the solvent for the oxidant,
Even if one side of the substrate exhibits hydrophobicity, the oxidant easily penetrates into that side as well, so it is difficult to retain the oxidant on only one side of the substrate. Then, for example, when one surface of the sheet-shaped base material is hydrophobic and the other surface is hydrophilic, the base material is immersed in an aqueous oxidant solution, or the hydrophilic surface is coated with the oxidant aqueous solution. The oxidant can be easily retained on the hydrophilic surface of the substrate by the method. When both sides of the sheet-shaped substrate are hydrophobic, the oxidizing agent aqueous solution can be repeatedly applied to one surface to retain the oxidizing agent on this one surface. Further, when both sides of the sheet-shaped substrate are hydrophilic, one side is treated with a water repellent such as a silicone type or a fluorine type to make it hydrophobic, and then immersed in an oxidant aqueous solution or the other hydrophilic side. By applying an oxidant aqueous solution to the surface of No. 3, the oxidant can be retained on this hydrophilic surface.

The space capable of holding the oxidizing agent may have such a spatial size that the oxidizing agent used can hold at least a molecular form or an aggregate. It is not preferable if the space is too small for the oxidant in the molecular state to hold, or if the space is too large for the oxidant in the aggregated state to hold. This space is distributed on or in the substrate as pores or gaps of various shapes. Specifically, in the case of pores, the size thereof has an average pore diameter of 0.001 to 100 μm, preferably
It is 0.005 to 50 μm. It is also known that the depth of pores is 0.001 μm or more, preferably 0.005 μm or more.

The form of a flat substrate having such characteristics is, for example,
Specifically, it is a porous material (plate-shaped molded product, sheet, film, filament), woven fabric, non-woven fabric, or the like.

As the base material, organic or inorganic base materials are used.
Examples of organic base materials include polyolefin-based, polyvinyl halide-based, polyfluorine-based, polyester-based, polyamide-based, polyimide-based, polyvinyl alcohol-based, polyacrylic-based, polycarbonate-based, rayon-based, and cellulose-based materials and the like. Copolymer system, mixed material system is used. As the inorganic base material, a carbonaceous base material, a metal base material, an alloy base material, a metal oxide base material, a metal carbide base material, a metal nitride base material, or a mixture thereof is used.
Further, a base material in which an organic base material and an inorganic base material are mixed is also used.

Specific examples of such a substrate include polyethylene, polypropylene, ethylene-propylene copolymer, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene terephthalate, and organic bases. Polybutylene terephthalate, polystyrene, polyamide, polyimide, polyamideimide, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polyacrylonitrile, polymethacrylonitrile, polymethylmethacrylate, polybutylmethacrylate, polystyrene-acrylonitrile, polycarbonate, rayon, methylcellulose ，
Nitrocellulose, carboxymethyl cellulose, etc. are used. Inorganic base materials include activated carbon, carbon black, graphite, chromium, titanium, nickel, gold,
Platinum, tantalum, copper, silver, iron, stainless steel, alumina, silica, silica alumina, zirconia, beryllium oxide, potassium titanate, silicon carbide, boron carbide, titanium carbide, molybdenum carbide, tantalum carbide, boron nitride, silicon nitride, Niobium nitride or the like is used.

As the compound having a conjugated double bond used in the present invention, a pyrrole-based compound, a thiophene-based compound, or the like is used alone or as a mixture. Preferably, a pyrrole-based or thiophene-based compound having no substituent at the 2,5 position of the ring skeleton structure of pyrrole or thiophene is used. Specific examples of the pyrrole compound include pyrrole, N-methylpyrrole, N-ethylpyrrole, Nn-propylpyrrole, Nn-butylpyrrole, N-phenylpyrrole, N-toluylpyrrole, N-naphthylpyrrole, 3-methylpyrrole, 3,5
-Dimethylpyrrole, 3-ethylpyrrole, 3-n-propylpyrrole, 3-n-butylpyrrole, 3-phenylpyrrole, 3-toluylpyrrole, 3-naphthylpyrrole, 3-methoxypyrrole, 3-5-dimethoxypyrrole, 3-ethoxypyrrole, 3-n-propoxypyrrole, 3-phenoxypyrrole, 3-methyl N-methylpyrrole, 3-methoxy N-methylpyrrole, 3-chloropyrrole, 3-bromopyrrole, 3-methylthiopyrrole, 3- Methylthio N-methylpyrrole and the like.

Specific examples of the thiophene compound include 2,2′-bithiophene, 3-methyl-2,2′-bithiophene, 3,3 ′.
-Dimethyl-2,2'-bithiophene, 3,4-dimethyl-2,
2'-bithiophene, 3,4-dimethyl-3 ', 4'-dimethyl-2,2'-bithiophene, 3-methoxy-2,2'-bithiophene, 3,3'-dimethoxy-2,2'-bithiophene , 2,2 ', 5', 2 "-ta-thiophene, 3-methyl-2,2 ', 5', 2" -ta-thiophene, 3,3'-dimethyl-2,2 ', 5', 2 ″ -terthiophene and the like.

The ratio of the oxidizing agent to the compound having a conjugated double bond is related to the amount of the copolymer produced, but is usually 0.001 to 10,000.
The molar ratio is preferably 0.005 to 5,000.

The polymer of the compound having a conjugated double bond is formed on the substrate in a gas phase atmosphere. That is, the polymer formation is carried out in a gas phase atmosphere in the presence of vapor of only a compound having a conjugated double bond, or in the presence of nitrogen, argon, air, other gas or mixed gas. The whole system can be operated under pressure, atmospheric pressure or reduced pressure, but it is usually preferable to operate under atmospheric pressure from the viewpoint of process control.

The reaction temperature is not particularly limited as long as it is a temperature at which a compound having a conjugated double bond can be polymerized, but it is usually -20 to 20.
It is carried out at 150 ° C, preferably 0-100 ° C. The reaction time is usually 0.01 to 200 hours, preferably 0.02 to 100 hours, though it depends on the reaction temperature, the amount of the oxidizing agent, the amount of the compound having a conjugated double bond, and the like. Then, after the polymerization reaction, the dark brown to black homogeneous polymer is formed on the portion of the substrate holding the oxidizing agent.

An oxidant is further retained on the above-produced polymer, and the compound having the same or different conjugated double bond is contacted to continue the polymerization reaction to increase the production amount of the polymer or to produce two or more kinds of compounds. Polymer formation can be obtained.

After the polymerization reaction is completed, the compound having the conjugated double bond remaining on the substrate and the oxidizing agent are removed. Usually, it can be removed by immersing and washing the substrate in water, alcohol or an organic solvent. Then, the conductive material of the present invention can be obtained by drying the substrate by a usual drying method.

In the secondary battery of the present invention, an electrode made of such a conductive material is used for both positive and negative electrodes, and this electrode is used for only one electrode, and the other electrode is made of metal, metal oxide or other In some cases, a known conductive polymer other than the reaction product of the present invention, a known organic compound, an organic compound, an organometallic compound or the like may be used as an electrode material. Using an electrode using this conductive material only for the positive electrode, taking the case of using a metal as the electrode material of the negative electrode, it is preferable to use one having an electronegativity of 1.6 or less as the metal constituting the negative electrode, Examples of such metals include Li, Na, K, M
g, Al or alloys thereof, and particularly Li
And Li alloys are preferred.

On the other hand, when the present invention is applied to a non-aqueous electrolyte secondary battery, a solution obtained by dissolving an electrolyte in an organic solvent is used as the electrolyte used at that time. Examples of such electrolytes include salts with cations such as metal cations having an electronegativity of 1.6 or less, cations such as organic cations, and anions. Examples of onium ions include quaternary ammonium ions, carbonium ions, oxonium ions and the like. In addition, as anions, BF ₄ ⁻ , ClO
^{_{4 -, PF 6 -, AsF}} 6 -, CF 3 SO 3 -, I -,
Br ⁻ , Cl ⁻ , F ^{− and the} like can be mentioned. Then, specific examples of such an electrolyte include lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ).
₄ ), lithium hexafluorophosphate (LiPF ₆ ),
Lithium tetrachloroaluminate (LiAlCl ₄ ),
Tetraethylammonium tetrafluoroborate ((C
₂ H ₅ ) ₄ NBF ₄ ), tetraethylammonium perchlorate ((C ₂ H ₅ ) ₄ NClO ₄ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium iodide (LiI), lithium bromide (LiBr). ) And the like, but are not limited to these.
Then, the conductive material of the present invention is used for both positive and negative electrodes, and LiBF
_{As an} example of a battery configured by using an electrolyte solution in which No. ₄ is dissolved as an electrolyte, BF ₄ ⁻ in the electrolyte solution is present in the conductive material in the positive electrode and the electroconductive material in the negative electrode is electrolyzed during charging. Li ⁺ in the liquid is doped respectively. On the other hand, during discharge, BF ₄ ⁻ and Li ⁺ doped in the positive and negative electrodes are released into the electrolytic solution, respectively.

The organic solvent that dissolves the electrolyte is preferably an aprotic one having a high dielectric constant, such as nitrile, carbonate, ether, nitro compound, amide, sulfur-containing compound,
Chlorinated hydrocarbons, ketones, esters and the like can be used. Further, such solvents may be used as a mixture of two or more kinds. As typical examples of these, acetonitrile, propionitrile, butyronitrile, benzonitrile, propylene carbonate, ethylene carbonate,
Tetrahydrofuran, dioxolane, 1,4-dioxane, nitromethane, N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, 1,2-dichloroethane, γ-butyrolactone, 1,2-dimethoxyethane, methyl phosphate, ethyl phosphate, etc. I can mention,
It is not limited to these.

The concentration of the electrolytic solution of the present invention is usually 0.001 to 10 mol / l, preferably 0.1 to 3 mol / l.

Such an electrolytic solution can be used not only by pouring but also by preliminarily impregnating the electrode using the conductive material of the present invention.

Further, in the present invention, a solid electrolyte can be used instead of the above electrolyte solution. Such solid electrolyte, for example, as a lithium conductive solid _{electrolyte, LiI, LiI-Al 2 O} 3, Li 3 N, LISI
CON, lithium ion conductive glass (for example, Li ₂ S
-P ₂ S ₅ -LiI system, etc.), γ _II -Li ₃ lithium ion conductor (e.g., _Li 4 SiO ₄ having a PO ₄ type structure
-Li ₃ PO ₃ system, etc.), lithium ion conductive polymer electrolytes (for example, polyethylene oxide-LiClO ₄ system, etc.), and those obtained by adding additives to them.

Further, although the method of forming the electrode as it is without performing the doping treatment on the conductive material has been described above, it is also possible to dope the dopant in advance and then use it as the electrode.

Further, in the present invention, in order to fix the electrode in the electrolyte, the electrode may be covered with glass, Teflon, polyethylene, a plate or the like having a drainboard shape or a hole.

When the conductive material according to the present invention uses, for example, the above-mentioned organic base material, the organic base material can also serve as a separator. If a conductive material using an inorganic base material as described above is used, the base material can also serve as a current collector.

Further, for example, when the substrate also serves as a current collector, a porous film of glass filter paper, Teflon, polyethylene, polypropylene, nylon or the like may be used as the separator.

<Operation> Since the above conductive materials have excellent oxidation resistance and do not undergo oxidative deterioration due to oxygen and moisture in the air, the management of the electrode manufacturing environment is easy and the storage stability of the electrode itself is not only good. In addition, it is possible to improve the charging efficiency and the cycle life without causing a transformation or decomposition due to the presence of oxygen or water in the battery or overcharging, and without a sharp increase in the voltage during charging.

Further, since this conductive material is obtained by polymerizing a compound having a conjugated double bond on a suitable base material in a gas phase atmosphere in the presence of an oxidizing agent, it is easy to manufacture and the cost is relatively low. Not only a uniform thickness but also a uniform thickness can be obtained, and the electrode material integrated with the separator or the current collector can be easily obtained, so that the battery assembling process can be greatly simplified. Furthermore, when a porous material is used as the base material, the liquid content of the electrode itself (electrolyte content)
Is improved and the charging / discharging efficiency of the battery is improved.

<Examples> The present invention will be specifically described below with reference to production examples of conductive materials according to the present invention and examples of secondary batteries.

Production Example 1-3 pore size 0.1~10μm conductive material, one surface _{Fe (ClO 4) 3 · 8H} 2 O- water saturation of polyethylene porous film on both sides of the hydrophobic film thickness 20 [mu] m (vertical 10 cm, horizontal 20 cm) Solution 3
It is applied twice to uniformly coat Fe (ClO ₄ ) ₃ on one side of the film.
The ingredients were retained. Next, place 4 ml of pyrrole on the bottom of the glass container (depth 10 cm, width 25 cm, height 15 cm),
The porous film obtained by the above treatment was hung from the upper part of a glass container, the upper part of the container was sealed with a glass plate and brought into contact with pyrrole vapor.

Upon contact with the pyrrole vapor, the porous film rapidly changed color from yellow to dark green, and then to black, forming polypyrrole on one side of the porous film. After the predetermined contact time shown in Table 1, the film was taken out and placed in methanol for 3 minutes.
After soaking for 0 minutes, unreacted pyrrole and Fe (ClO ₄ )
_{The three} components were extracted and removed. After repeating this operation three times, it was air-dried to obtain a flexible film having one black surface.

The thickness of this film and the results of measuring the electric conductivity in the horizontal direction on one surface of the film with an electrode placed on one surface of the film are also shown in Table 1.

The electrical conductivity was measured by the four-terminal method.

Moreover, when the electric conductivity in the vertical direction of the film was measured by placing electrodes on one surface and the other surface of the film, respectively, it was 10 ^-10 Scm ^-1 or less, and it was possible to conduct the electric conductivity on only one surface. I was able to confirm that.

3. Manufacturing example of conductive material The same procedure as in Production Example 3 was performed except that a polypropylene porous membrane (Duraguard 2400) having a maximum pore size of 0.02 × 0.2 µm and a film thickness of 25 µm and having hydrophobic properties on both sides was used. As a result, the film thickness was 28 µm and one surface was black. A glossy film was obtained. This film has a horizontal electrical conductivity of 6.5.
× 10 ^-2 Scm ^-1 and vertical electric conductivity is 10
_{It was -10} Scm ^-1 or less, and it was possible to conduct only one surface.

Manufacturing Example 5 of Conductive Material 220 μm in film thickness whose surface is hydrophilized with a surfactant,
A polypropylene non-woven fabric with a weight of 75 g / m ² is dipped in a 30% aqueous potassium hydroxide solution, heat-treated at a temperature of 60 ° C. for 1 hour, washed thoroughly with water and dried to remove the surfactant, and the surface of the non-woven fabric is then removed. Becomes hydrophobic.

Except for using this non-woven fabric, the Fe (ClO ₄ ) ₃ component was retained on one side of the non-woven fabric and brought into contact with pyrrole vapor in the same manner as in Production Example 2 above, and the film thickness was 230 μm.
A non-woven fabric having a black surface on one side was obtained. The electric conductivity of this nonwoven fabric in the horizontal direction is 1.8 × 10 ^-1 Scm ^-1 and the electric conductivity in the vertical direction is 10 ^-10 Scm ^-1 or less, so that it is possible to conduct only one side of the nonwoven fabric. It was

Comparative Production Example 1 of Conductive Material 1 The same treatment as in Production Example 5 was performed except that the treatment with a 30% aqueous potassium hydroxide solution was not performed. As a result, the oxidizing agent could not be held on only one side of the nonwoven fabric and was contacted with polypyrrole vapor. After that, the non-woven fabric was blackened because polypyrrole was generated on both sides. The horizontal electrical conductivity of this non-woven fabric is 1.5 ×
10 ^-1 Scm ^-1 , vertical electric conductivity is 4.8 × 10 ^-2 S
It was cm ⁻¹ , and it was not possible to make only one surface of the non-woven fabric conductive.

Another is the manufacturing example using _{Fe (ClO 4) 3 · 8H} 2 O- methanol saturated solution instead of Comparative Production Example 2 oxidizing agent solution as _{Fe (ClO 4) 3 · 8H} 2 O- water-saturated solution of conductive material As a result of carrying out in the same manner as in 1, a film was obtained in which both surfaces were blackened due to polypyrrole formation. The electrical conductivity of this film is 2.8 × 10 ^-1 Scm ^{-1 in} the horizontal direction and 1.8 × 10 ^{-2 in the} vertical direction.
It was Scm ^-1 , and it was not possible to make only one surface of the film conductive.

Manufacturing Example 6 of Conductive Material Pore diameter 0.1 to 10 μm, film thickness 80 μm, length 10 cm, width 20
On one side of a polyethylene porous film having a double-sided hydrophobicity of cm, draw 40 straight lines with a width of 2 mm in the longitudinal direction with a water saturated solution of FeCl ₃ .6H ₂ O, and air-dry. Placed in a steam atmosphere. As a result, a film having 40 black straight lines with a width of 2 mm on one side was obtained. This film has an electrical conductivity of 1.3 × 10 ^{-1 in the} longitudinal direction.
Scm ^-1 was shown, and insulating properties were exhibited in the lateral and vertical directions.

In this way, a conductive film having conductivity only in the longitudinal direction on one side of the film could be obtained.

Production Example 7 of Conductive Material Using 3-methylpyrrole instead of pyrrole, Fe
_{(ClO 4) 3 · 8H 2} O Cu (BF 4) instead of the results other using ₂ 40% water solution was carried out as in the above Production Example 1, a film thickness of 22μm one side of the black film was gotten. The electrical conductivity of this film in the horizontal direction is
1.8 × 10 ^-3 Scm ^-1 , with a vertical electrical conductivity of 1
It was 0 ^-10 Scm ^-1 or less.

Production Examples 8 to 14 of Conductive Material Various oxidizers having various pyrrole compounds shown in Table 2 were allowed to exist on one surface of various porous films and 2
The results of polymerization by contacting for 4 hours are also shown in Table 2.

Production Examples 15 to 21 of Conductive Material The results obtained in the same manner as in Production Example 1 except that the various non-woven fabrics shown in Table 3 were used are also shown in Table 3.

In the case of Production Examples 16, 17, 18, and 20.21, one surface of each non-woven fabric was previously spray-coated with a fluorine water repellent agent to make the one surface hydrophobic, and then each non-woven fabric was added to a saturated aqueous solution containing an oxidizing agent. Was dipped to hold the oxidizer on the surface which was not subjected to the hydrophobic treatment.

Production Examples 22 to 28 of Conductive Material Table 4 also shows the results obtained in the same manner as in Production Example 1 except that various woven fabrics or nonwoven fabrics shown in Table 4 were used.

In each of these production examples, each woven fabric and non-woven fabric was spray-coated with a silicon water repellent agent on one side thereof to be hydrophobized on one side, and then an oxidant was coated on the surface not hydrophobized. And kept it.

Production Example 29 of Conductive Material Table 5 shows the results of measuring the change with time of the electrical conductivity of the conductive film obtained in Production Example 2 above.

From the above results, it was shown that the change in electric conductivity of the conductive film according to the present invention was extremely slight.

Production Example 30 of Conductive Material The same procedure as in Production Example 3 of conductive material except that 5.0 g of 2,2′-bithiophene was used instead of pyrrole and the reaction temperature was 70 ° C. A film was obtained. The electrical conductivity of this film is horizontal
It was 7.5 × 10 ^-5 Scm ^-1 , and 10 ^-10 Scm ^-1 or less in the vertical direction.

The conductive material obtained in Production Example 1 was used as a positive electrode material, which was punched into a predetermined size to be a positive electrode, and lithium punched into a predetermined size was used as a negative electrode. And
A battery according to the present invention having a structure shown in FIG. 1 (A), using these positive and negative electrodes and an electrolytic solution prepared by dissolving lithium tetrafluoroborate LiBF ₄ (electrolyte) in propylene carbonate (solvent). (Invention product A) was prepared.

The conductive material obtained in Production Example 23 above was used as the positive electrode material, punched out to a predetermined size, was used as the positive electrode, and a separator made of polypropylene nonwoven fabric was used in the same manner as in the case of the product A of the present invention. A battery according to the present invention (product B of the present invention) shown in FIG. 1 (B) was produced.

On the other hand, a conventional polypyrrole film obtained by electrolytic oxidation polymerization was used as a positive electrode material, which was punched to a predetermined size to be a positive electrode, and this positive electrode was pressed to the bottom surface of the positive electrode can through a positive electrode current collector and pressure-bonded, and A comparative battery (comparative product C) was prepared in the same manner as the product A of the present invention, except that a separator made of polypropylene nonwoven fabric was used.

The above three batteries were repeatedly charged and discharged at a current of 0.1 mA for 1 hour, and then discharged at a current of 0.1 mA until the battery voltage reached 2.5 V.

FIG. 2 shows the time-dependent changes in the battery voltage of the invention product A and the comparative product C during charge and discharge at the 60th cycle. still,
In the figure, the solid line shows the voltage change during charging, and the dotted line shows the voltage change during discharging. As is clear from FIG. 2, the product A of the present invention has a lower charging voltage and a higher discharging voltage than the comparative product C, and thus it is understood that the charging / discharging efficiency is improved accordingly.
By the way, the charge / discharge efficiency in this cycle was 92% for the product A of the present invention, and 80% for the comparative product C. The reason why the charging / discharging efficiency of the product A of the present invention has been improved in this way is that the conductive material used as the positive electrode of the product A of the present invention uses a porous film as a base material so as to be liquid-absorbing. In addition to improving the liquid content of the positive electrode itself,
It is considered that in the product A of the present invention, the distance between the electrodes was smaller than that of the comparative product, and the internal resistance was reduced accordingly, and as a result, the increase of the charging voltage was suppressed and the discharge voltage was improved.

Further, FIG. 3 shows the cycle change of the charge / discharge efficiency (%) of the product B of the present invention and the comparative product C. As shown in the figure, the charge / discharge efficiency of the comparative product C is reduced after about 60 cycles, and is reduced to 50% at 100 cycles. On the other hand, it can be seen that the product B of the present invention not only exhibits higher charge / discharge efficiency than the comparative product C throughout the entire cycle but also maintains a high charge / discharge efficiency of 90% at the 100th cycle. It is considered that the reason why the cycle characteristics of the comparative product C are so bad is that the polypyrrole film of the positive electrode peels off from the positive electrode current collector during the charge / discharge cycle, and the adhesiveness and contact property between the two gradually deteriorate. To be
In the case of the product B of the present invention, a conductive material using carbon cloth as a base material was used as the positive electrode, and this base material also served as the positive electrode current collector. The adhesion to the body is remarkably good, and the degree of peeling of the polypyrrole from the current collector during the charging / discharging cycle is extremely small, and as a result, it is considered that the cycle characteristics are improved.

In the above description, the conductive material is used only for the positive electrode, but it is clear that the same effect can be obtained when the conductive material of the present invention is used for the negative electrode or the positive and negative electrodes.

<Effects of the Invention> According to the secondary battery of the present invention configured as described above,
Since an electrode made of a conductive material that has excellent oxidation resistance and is easy to manufacture and inexpensive is used, the management of the electrode manufacturing environment is facilitated and the storage stability of the electrode itself is improved, and there is no inconvenience such as a sharp increase in charging voltage. Moreover, the battery cost is not increased. Further, since this conductive material can be used as an electrode material in which a base material also serving as a separator or a collector and a conductive polymer layer are integrated, the battery assembly process can be simplified and the separator can be used as a base material. In the case of being used also, the charging voltage can be suppressed and the discharge voltage can be raised by reducing the internal resistance of the battery, and in the case of being used also as the current collector, the cycle characteristics can be improved.
In addition, when a porous material is used as the base material of the conductive material to be used, there are advantages that the liquid content of the electrode is improved and the battery characteristics are improved, and its industrial utility value is great.

[Brief description of drawings]

1 (A) and 1 (B) are cross-sectional views showing a battery structure of an embodiment of the present invention, respectively, and FIG. 2 is a graph showing a time-dependent change in battery voltage during charge / discharge cycles of the product of the present invention and a comparative product , Third
The figure is a graph showing the cycle characteristics of the product of the present invention and the comparative product. 1 ... Positive electrode, 2 ... Negative electrode, 3 ... Separator, 4 ... Insulating packing, 5 ... Positive electrode can, 6 ... Negative electrode can, 7 ... Negative electrode current collector, 8 ... Carbon cloth, 9 ... Porous polyethylene film.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Nobuhiro Furukawa 2-18 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Masahisa Fujimoto 2-18 Keiyo Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. Incorporated (72) Inventor Koji Nishio 2-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) Reference JP-A-59-18578 (JP, A)

Claims (5)

[Claims] 1. A substrate having a space capable of holding an oxidant and at least one surface of which is hydrophobic is treated with the oxidant to allow the oxidant to be retained only on one side of the substrate, A compound having a conjugated double bond is polymerized on the base material in a phase atmosphere, and a conductive material obtained by forming a polymer of the compound on any one surface of the positive electrode or the negative electrode. A secondary battery characterized by being used as. 2. A substrate having one surface being hydrophobic and the other surface being hydrophilic is dipped in an oxidizing agent aqueous solution, or the other surface is coated with an oxidizing agent aqueous solution and the other surface is oxidized. The secondary battery according to claim 1, wherein a conductive material holding an agent is used. 3. A conductive material having a hydrophobic base material coated on one surface thereof with an oxidizer aqueous solution and having the oxidizer held on the one surface thereof. Range first
The secondary battery according to the item. 4. The secondary battery according to claim 1, wherein a conductive material obtained by treating one surface of a hydrophilic substrate with a water repellent is used. 5. The secondary according to claim 1, 2, 3 or 4, wherein the compound having a conjugated double bond is a pyrrole-based or thiophene-based compound. battery.