JPH04245166A - Secondary battery - Google Patents

Abstract

PURPOSE:To prevent the dissolution of a porous film and provide high charge- and-discharge capacity by using a dry polyaniline porous film in which a proton acid is not doped and which has a predetermined bulk density in a dedoped condition. CONSTITUTION:In a secondary battery built up in such constitution which comprises a positive electrode composed of a polyaniline porous film, an electrolyte, and a negative electrode, the polyaniline porous film which has been dried without proton acid doping and has a bulk density ranging from 0.1 to 0.9g/cm<2> under a dedoped condition. Consequently, since the solubility of the polyaniline porous film in an organic solvent lowers, the reliability of the secondary battery using it can be improved. Furthermore, since the permeability of the electrolyte can be enhanced without the deterioration in the strength of the film, a secondary battery having high productivity and large service capacity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery comprising a positive electrode made of a porous polyaniline film, an electrolyte, and a negative electrode.

0002

BACKGROUND OF THE INVENTION In recent years, there have been expectations for the application of conductive polymer materials such as polyacetylene and polypyrrole to secondary batteries, and polyaniline has been attracting attention as one such material. It is well known that the above polyaniline can be synthesized by oxidizing aniline, and its production methods include a chemical oxidation polymerization method that utilizes the oxidizing power of peroxides, metal ions, metal complex compounds, etc., and an acidic aqueous solution. Among these methods, a method is known in which aniline is electrolytically oxidized and polymerized.

In the case of the above-mentioned chemical oxidative polymerization method, for example, a method is known in which polyaniline is synthesized by oxidative polymerization of aniline using an oxidizing agent such as ammonium persulfate [A.G. MacDamido et al. .G.MacDear
Mid et al. ) Molecular Crystals and Liquid Crystals Volume 119, 1
~4 (1985), Part E, 173 ~180
See page]. It is also known to melt the polyaniline produced in this way and form it into a film or to make it porous.

0004

[Problems to be Solved by the Invention] However, conventional film-like or porous film-like polyaniline is easily dissolved in organic solvents, so when used as an active material in batteries, it may cause problems such as increased self-discharge. I had an issue. For example, as shown in JP-A-2-220373, aniline is chemically oxidized and polymerized, the resulting polyaniline is treated with an alkali, dissolved in a solvent, and then a porous film is created by a casting method. A method has been proposed in which this porous film is doped with protonic acid and used as a positive electrode active material of a secondary battery.

[0005] As described above, if a post-treatment (such as doping with protonic acid as described above) is performed after forming a porous film, the porous film becomes insolubilized. In addition, it was conventionally thought that high charge/discharge capacity could be obtained by using the protonic acid-doped porous film as a positive electrode of a secondary battery. However, when the protonic acid doped polyaniline film was used as a battery electrode, satisfactory results could not always be obtained in terms of charge and discharge capacity.

The present invention has been made in view of the current situation, and an object thereof is to provide a secondary battery that can obtain a high charge/discharge capacity while preventing the polyaniline porous film from dissolving.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a secondary battery comprising a positive electrode made of a polyaniline porous film, an electrolyte, and a negative electrode, as the polyaniline porous film. It is characterized in that it is dried without being doped with protonic acid and has a bulk density of 0.1 to 0.9 g/cm3 in an undoped state.

An example of a method for manufacturing a secondary battery having the above structure will be explained below in the order of manufacturing steps: polyaniline synthesis step, dedoping step, polyaniline porous film preparation step, drying step, and battery preparation step. [Polyaniline synthesis process] Polyaniline can be synthesized by oxidative polymerization using an oxidizing agent (hereinafter referred to as chemical polymerization), and electrochemical oxidative polymerization using an electrode (hereinafter referred to as electrolytic oxidative polymerization). A known method called "legal" is used. ■Chemical oxidation polymerization method In this method, polyaniline is synthesized by mixing an acidic solution of aniline and an oxidizing agent.

At this time, the oxidizing agent has an oxidation-reduction potential of 0.6 V or more and 2.5
It is desirable to use a material of V or less. This is 0.
Aniline does not polymerize at voltages below 6V, while at voltages below 2.5V
When V is exceeded, decomposition of aniline occurs. On the other hand, within the above range, aniline with good polymerization yield and properties can be obtained.

Examples of oxidizing agents include ferric salts, persulfates, hydrogen peroxide, and dichromates. Specifically, ferric salts include ferric perchlorate, ferric periodate, ferric borofluoride, ferric hexafluorophosphate, ferric sulfate, ferric nitrate, and chloride. There is a second railway etc. In addition, persulfates include ammonium persulfate, sodium persulfate, potassium persulfate, etc., and dichromates include, but are not limited to, potassium dichromate, sodium dichromate, etc. It's not a thing. however,
Among these oxidizing agents, ferric perchlorate, ferric periodate, ferric borofluoride, ferric hexafluorophosphate, ammonium persulfate, and hydrogen peroxide are particularly preferred because they give good results. . Further, these oxidizing agents may be used alone or in combination of two or more.

[0011] Polyaniline suitable for film formation preferably has excellent solubility. Therefore, the amount of the oxidizing agent used is preferably 0.1 to 5 times, more preferably 0.1 to 2 times, and particularly preferably 0.5 to 2 times the amount of aniline. Anions of these oxidizing agents other than hydrogen peroxide or anions generated after the oxidation reaction are incorporated into polyaniline, but there are no particular restrictions as they are removed during dissolution. ■Electrolytic oxidative polymerization method In this method, polyaniline is synthesized by electrolytically polymerizing aniline in the presence of an acid that is stable under electrolytic conditions.

In this case, various methods can be used for electrolytic oxidative polymerization using an acidic aqueous solution of aniline. Specifically, constant current method, constant potential method, constant voltage method,
Potential scanning method and potential step method can be mentioned, but
In order to control the amount of electricity supplied, it is preferable to use a constant current method or a constant potential method. The current density in electrolytic oxidation polymerization varies depending on the aniline concentration, acid concentration, and polymerization temperature, but is usually carried out in the range of 0.001 to 500 mA/cm2. Even within that range, 0.001 to 50 mA/cm2 is preferable, and more preferably 0.1 to 20 mA/cm2.
A range of is particularly preferred. In the constant potential method and the constant voltage method, conditions may be selected so that the current density falls within the above range. For example, in the case of constant potential method, 0.8V vs Ag/AgCl
~10V vs. Ag/AgCl is preferred, 0.8V
vs Ag/AgCl ~2.0V vs Ag/A
Particularly preferred is gCl. ■ Points to note regarding both of the above polymerization methods (1) The acid used in both polymerization methods is stable under chemical oxidative polymerization and electrolytic oxidative polymerization of aniline, forms a salt with aniline, and dissolves aniline in an aqueous solution. Any acid may be used. Specific examples include perchloric acid, hydrofluoroboric acid, hexafluorophosphoric acid, periodic acid, sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, etc. Hydrohydric acid, hexafluorophosphoric acid, and periodic acid are preferred because they give good results. The concentration of these acids may be at least the equivalent of the aniline used, and is usually preferably at least 0.1 normal.

(2) The concentration of aniline used in the reaction is not particularly limited. Usually the upper limit is the concentration that dissolves in acidic solution. However, since aniline is oxidized by the reaction and precipitated as polyaniline, there is no particular problem even if it is used in a concentration higher than the dissolved concentration because it will dissolve during the reaction and further reaction will proceed. On the other hand, the lower limit is not particularly limited either, but it is not efficient if the concentration is too low, so it is usually preferable to use it at a concentration of 0.1 mol/l or more. The purity of the aniline used is not particularly limited, but is preferably 95% or more.

(3) The reaction is carried out using an acidic solution containing aniline;
Alternatively, in the chemical oxidative polymerization method, a liquid containing a slurry of aniline salt may be stirred with the oxidizing agent as it is, or with a solution containing the oxidizing agent added thereto.On the other hand, in the electrolytic oxidative polymerization method, the above liquid is stirred between a pair of electrodes. What is necessary is to put it into an electrolytic bath and electrolyze it. (4) There are no particular restrictions on the reaction temperature and reaction time, but the reaction is usually carried out at a temperature above the freezing point and below the boiling point of the solution containing aniline. However, in order to obtain polyaniline that can be easily formed into a film, it is preferable to carry out the reaction at a temperature of 50°C or lower, more preferably 40°C or lower. The reaction time is not particularly limited and can be determined as appropriate in consideration of the oxidizing agent used and the amount of current applied, but is generally in the range of 5 minutes to 100 hours, more preferably 1
It ranges from 0 minutes to 50 hours. [Dedoping process] (1) The polyaniline obtained by polymerization is doped with anions derived from the oxidizing agent or acid used in the reaction (incorporating anions), so it increases its solubility. Therefore, it is necessary to perform dedoping (removal of anions) before dissolution. This anion can be removed by bringing an alkaline compound that does not react with the polyaniline skeleton into contact with it.

[0015] The alkali used at this time may be used, for example, if the pH of the solution is 1 after adding the polyaniline obtained by polymerization.
There is no particular restriction as long as it is 1 or more, and examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, and aqueous ammonia. (2) The solvent for dissolving the polyaniline obtained as described above is not particularly limited as long as it can sufficiently dissolve the polyaniline. Specifically, N, N
-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, propylene carbonate,
γ-Butyrolactone, N-methyl-2-pyrrolidone, 1
, 3-dimethyl-2-imidazolidinone, etc., but especially N,N-dimethylformamide, N,N-
dimethylacetamide, N-methyl-2-pyrrolidone,
1,3-dimethyl-2-imidazolidinone is preferred.

[0016] Furthermore, if the polyaniline is not completely dissolved during dissolution and there is insoluble matter, it may or may not be separated. Furthermore, the concentration of dissolved polyaniline may be within a range that provides sufficient viscosity to maintain its shape during film forming, and although it depends on the polyaniline synthesis method and the type of solvent, it is usually 1 to 20% by weight. range, preferably 2 to 15% by weight, more preferably 3 to 10% by weight.
It is. [Porous polyaniline film production step] There are no particular limitations on the method of forming a film from the solution obtained in the above step. For example, a method of coating on a base material that is insoluble in the solvent used, a spin coating method, a casting method, a dipping method,
A bar coating method, a roll coating method, etc. are used. For example, a polyaniline solution may be cast onto a base material such as a glass plate, a Teflon plate, or a polyethylene terephthalate (PET) sheet.

[0017] Here, in this step, the bulk density is 0.1
There are, for example, the following four methods for obtaining a film of ~0.9 g/cm3. (1) A method in which a polyaniline solution is cast onto a base material and then immersed in a poor solvent for polyaniline to solidify the film before drying. (2) A method in which a powder that is insoluble in the solvent used for the polyaniline solution but soluble in the poor polyaniline solvent is mixed into a film, and after film formation, the powder is dissolved and removed.

(3) A method in which a material that is soluble in both a polyaniline solution and a polyaniline poor solvent is mixed, and after forming a film, the mixed material is eluted, or a blowing agent is mixed,
A method of foaming after forming into a film. (4) Other methods used in the production of porous polymer films, such as applying a polyaniline solution to a base material, gelling it, and drying it.

Among these methods, as shown in (1), a method in which a polyaniline solution is applied onto a substrate, cast or otherwise cast, and then immersed in a poor solvent to solidify a film before drying is a method. is practical and preferable because it can be easily replaced with a poor solvent before drying. Moreover, the bulk density of the polyaniline porous film obtained can be adjusted by changing the polyaniline solution concentration, the type of poor solvent, the immersion time, the temperature, etc.

[0020] Examples of the poor solvent used in the method of coagulating with a poor solvent include water, alcohols having 4 or less carbon atoms such as methanol and ethanol, acetone, acetonitrile, and mixtures thereof, and more preferably water or alcohols and It is a mixture of them. After coagulation, a porous polyaniline film is obtained by peeling the film applied onto the base material from the base material and drying it, or by drying and peeling it from the base material. In this case, when considering use as an electrode, it is advantageous to use a current collector or a solid electrolyte thin film as a base material because there is no need to peel it off and it can be used as is. The current collector used here is not particularly limited, but stainless steel nets and thin stainless steel plates are exemplified. Further, the solid electrolyte thin film may be any material as long as it is not easily dissolved in the solvent of the polyaniline solution. [Drying Step] In this drying step, the obtained porous film-like polyaniline is insolubilized by sufficiently drying. Therefore, it is substantially insoluble in the solvent used in the battery.

[0021] This step is generally performed by heating under an inert atmosphere, and examples include vacuum drying and heating in nitrogen gas. The drying temperature used depends on the solvent and drying method, but below room temperature the solvent will not evaporate sufficiently, and
Polyaniline decomposes at high temperatures exceeding 00°C. Therefore, the drying temperature is 25°C to 400°C, preferably 40°C to 250°C, more preferably 40°C to 130°C.
It may be selected as appropriate within the range of °C.

When the polyaniline porous film obtained as described above is used as an electrode of a secondary battery, if the bulk density of the polyaniline porous film is less than 0.1 g/cm3, the strength of the film is low and it becomes difficult to handle. On the other hand, 0.
If the density exceeds 9 g/cm3, the penetration of the electrolyte becomes insufficient and the discharge capacity becomes small. Therefore, the bulk density is 0.1 to 0.9 g/cm3, preferably 0.1
5 to 0.8 g/cm3, more preferably 0.2 to 0.
6 g/cm3.

[0023] Furthermore, there is no particular limit to the thickness of the film, and films of various thicknesses can be produced depending on the concentration and amount of the polyaniline solution, the manufacturing method, etc. However, if the material is too thin, it will not be strong enough to be used as a battery electrode.
If it is too thick, the flexibility of the film will be lost, which is not preferable. Therefore, the thickness of the film used in the battery of the present invention is 0.1 to 1000 μm, preferably 1 to 300 μm, more preferably 10 to 200 μm.
Configure it so that

Further, the chemical structure of the base structure of neutralized polyaniline is said to be an emeraldine structure (X, Y≈0.5) shown in Chemical Formula 1 below.

[0025]

[Chemical formula 1]

[0026] In the above equation 1, 0≦X≦1
, 0≦Y≦1, and X+Y=1. Here, the redox reaction of polyaniline is said to be mainly carried out by the amine structure, and in fact, in order to increase the capacity, reduction treatment is performed and x in the formula approaches 1 to form a leucoemeraldine structure. has also been reported. Doping with protonic acid has also been carried out.

However, in the present invention, it has been confirmed through experiments that a porous polyaniline film with a higher capacity than doping with protonic acid can be obtained even without the above treatment. [Battery production process] ■Positive electrode When the polyaniline porous film obtained as described above is used as a positive electrode, dopants used in general conductive polymer compounds such as polyacetylene can be effectively used. . Specifically, PF6 −, SbF6 which are halogen compound anions
-, AsF6-, I-, Br-, Cl-, I
3 − , AlCl4 − etc., perhalogenate ion ClO4 − etc., organic sulfonic acid ion C
F3 SO3 − , CH3 SO3 − , following chemical formula 2
There are ions shown in , SO4 2-, NO3 -, etc.

[0028]

[Case 2]

Practically, a substance containing these salts is used as an electrolyte. Specific examples of these include LiPF
6, LiSbF6, LiAsF6, LiClO4
, NaI, NaPF6, NaSbF6, NaAs
F6, NaClO4, KI, KPF6, KSbF
6, KAsF6, KClO4, (n-Bu)4
N+ AsF6 − , (n-Bu) 4 N+
PF6 − , (n-Bu) 4 N+
Examples include ClO4 − and ZnSO4. These electrolytes may be used alone or in combination of two or more. ■Negative electrode: Li, Na, K, Mg, Ca, Pb, Zn
Examples include metals such as Al and their alloys, conductive polymer compounds such as polyacetylene, polyparaphenylene, polyparaphenylenevinylene and their derivatives, and carbon-based materials such as carbon fiber and graphite, but these are not necessarily included. It is not limited. ■Battery configuration Configuration of a secondary battery that can be used in the present invention (positive electrode/electrolyte/
Negative electrode) is polyaniline/electrolyte/conductive polymer (cation doping), polyaniline/alkali metal salt electrolyte/alkali metal or aluminum-alkali metal alloy, polyaniline/electrolyte/carbon-based material (cation doping), polyaniline/electrolyte /active metal electrode (Pb
, Zn, etc.), but the invention is not necessarily limited to these.

The electrolyte medium does not need to be liquid as long as electrochemical transfer of the dopant is possible, and a solid medium such as an inorganic or organic solid electrolyte can also be used. However, liquid ones are generally used. Moreover, water or an organic solvent can be used as the solvent (medium) for the electrolyte, and there is no particular restriction. 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, dichloroethane, γ-butyrolactone, dimethylsulfoxide, dimethylformamide, dioxolane, acetonitrile, benzonitrile, nitromethane, dimethylacetamide, etc., but are not limited to these. do not have. These organic solvents may be used alone or in combination of two or more.

The electrolyte concentration in the electrolytic solution is not particularly limited, and is controlled depending on the type of electrolyte and solvent used. However, the range is usually preferably from 0.001 to 10 mol/l, and more preferably from 0.01 to 2 mol/l. [Summary] As described above, after dedoping (neutralizing) the polyaniline obtained by polymerization, this was dissolved to create a solution, and this solution was further used to create a polyaniline porous film. ,dry. At this time, by a method such as changing the concentration of the above solution, a polyaniline porous film (dried without doping with protonic acid) used for the positive electrode of the present invention, which has a bulk density of 0.1 to 0.9 g/cm3) will be produced.

[0032]

[Function] When a dried polyaniline porous film is used as the positive electrode as in the above structure, the solubility in organic solvents becomes low, so reliability can be improved, and the bulk density becomes 0 in the undoped state. If it is in the range of .1 to 0.9 g/cm3, the permeability of the electrolytic solution is improved without reducing the film strength, so the discharge capacity of the battery using this can be increased while improving the handleability.

[0033]

[Embodiment] An embodiment of the present invention will be described below. [Example 1] The secondary battery of the present invention is produced through the following steps: synthesis of soluble polyaniline and dedoping, production and drying of a polyaniline porous film, and battery production. The steps will be explained below in order.

(Synthesis of soluble polyaniline and dedoping step) First, 0.015 mol of aniline was dissolved in a 1N aqueous perchloric acid solution (30 ml). Next, 0.
A solution of 0.15 mol of ammonium persulfate dissolved in a 1 N perchloric acid aqueous solution (20 ml) was slowly added dropwise to the above perchloric acid aqueous solution, and after reacting for 1 hour under ice cooling, the formed precipitate was filtered. I washed it with water. Next, this precipitate was added to a 1N aqueous sodium hydroxide solution to remove anions (dedoping treatment). Thereafter, in order to remove unreacted sodium hydroxide, washing with water and methanol was thoroughly performed. Thereafter, the treated polyaniline was placed in a vacuum dryer and vacuum dried at 60° C. for 6 hours to obtain powdered polyaniline. This polyaniline is 1,3-dimethyl-2-imidazolidine (D
It was soluble in N-methyl-2-pyrrolidone (NMP) and N-methyl-2-pyrrolidone (NMP).

(Preparation and drying process of polyaniline porous film) First, the above soluble polyaniline (0.20g
) was dissolved in DMI (3.80 g) to prepare a 5% by weight solution, and this solution was cast onto a glass plate. Next, the glass plate was immersed in methanol for 2 hours to condense it, then pulled out and peeled off. Thereafter, this peeling film was vacuum dried at 60° C. for 6 hours to obtain a polyaniline film.

The film-like polyaniline thus obtained had an average thickness of 174 μm and a bulk density of 0.33 g/c.
m 3 , and observation using a scanning electron microscope (SEM) confirmed that the surface was porous. (Battery manufacturing process) First, the film-like polyaniline was cut into 1 cm square pieces, and then a platinum mesh was wrapped with this to create a positive electrode.A lithium piece was used as a negative electrode, and LiBF4
A secondary battery was fabricated using propylene carbonate dissolved in a proportion of 1 mol/l as an electrolyte.

The secondary battery thus produced is hereinafter referred to as the (A1) battery. [Example 2] A polyaniline film was prepared in the same manner as in Example 1, except that the concentration of the polyaniline solution was changed to 3% by weight. The obtained film-like polyaniline had an average thickness of 43 μm and a bulk density of 0.28 g/cm3,
When observed with SEM, it was confirmed that the surface was porous.

A secondary battery was also produced in the same manner as in Example 1 using the above film-like polyaniline. The secondary battery thus produced is hereinafter referred to as an (A2) battery. [Comparative Example 1] First, soluble polyaniline (0.08 g) synthesized in the same manner as in Example 1 was dissolved in NMP (3.92 g).
g) to prepare a 2% by weight solution, and this solution was cast onto a glass plate. Next, this glass plate was vacuum-dried at 100° C. for 4 hours to volatilize the solvent, and then peeled off to obtain a polyaniline film.

The film-like polyaniline thus obtained has an average thickness of 56 μm and a bulk density of 1.0 g/cm3.
When observed using SEM, it was confirmed that the surface was dense. Furthermore, a secondary battery was produced in the same manner as in Example 1 using the above film-like polyaniline.

The secondary battery thus produced is hereinafter referred to as the (X1) battery. [Comparative Example 2] First, a 5% by weight polyaniline solution was prepared under the same conditions as in Example 1, and this solution was cast onto a glass plate. Next, the above solution was heated with the glass plate at 100℃ for 2 hours.
After vacuum drying for a period of time to volatilize the solvent, it was peeled off to obtain a polyaniline film.

This was immersed in a 1N aqueous perchloric acid solution for 5 hours to dope with perchlorate ions, washed with water and methanol, and dried at 60° C. for 6 hours. Note that the doping rate was 16.7% by weight based on the weight change before and after the acid treatment. In addition, the film-like polyaniline obtained in this way is
The average thickness is 37 μm, the bulk density is 1.0 g/cm3, and S
When observed by EM, it was confirmed that the surface was dense.

Furthermore, a secondary battery was produced in the same manner as in Example 1 using the above film-like polyaniline. The secondary battery thus produced is hereinafter referred to as an (X2) battery. [Comparative Example 3] A polyaniline film was prepared in the same manner as in Example 2, and then immersed in a 1N perchloric acid aqueous solution for 2 hours to dope it with perchlorate ions. Next, the polyaniline film was washed with water and methanol, and then dried at 60° C. for 6 hours. Note that the doping rate was 17.3% by weight based on the weight change before and after the acid treatment.

The obtained film-like polyaniline had an average thickness of 76 μm and a bulk density of 0.36 g/cm 3 , and when observed with an SEM, it was confirmed that the surface was porous. Furthermore, a secondary battery was produced in the same manner as in Example 1 using the above film-like polyaniline. The secondary battery thus produced is hereinafter referred to as an (X3) battery. [Experiment] The (A1) battery of the present invention, the (A2) battery, and the (X1) to (X3) batteries of the comparative examples were repeatedly charged and discharged, and the discharge capacity of each battery was examined.The results are shown in Table 1. Shown below. The experimental conditions were in an argon atmosphere.
The conditions were to charge to 4.0 V at a constant current of 0.25 mA/cm2 and then discharge to 2.5 V at a constant current of 0.25 mA/cm2, and charging and discharging were repeated under these conditions.

[0044]

[Table 1]

As is clear from Table 1 above, the present invention (
It is recognized that the discharge capacity of the A1) battery and the (A2) battery is significantly larger than that of the comparative examples (X1) to (X3) batteries. Specifically, the comparative example (
X1) Since the bulk density of the battery is 1.0 g/cm3, which is very large, the penetration of the electrolyte becomes insufficient and the discharge capacity becomes small. In addition, the bulk density of the comparative example (X2) battery was 1.0 g/
cm3, which is very large, but because it is doped with protonic acid (perchloric acid), the discharge capacity increases. However, in this case as well, the increase in discharge capacity is insufficient. Furthermore, in the comparative example (X3) battery, the bulk density was 0.3.
Although it is small at 6 g/cm3, the increase in discharge capacity is still insufficient due to the doping with protonic acid (perchloric acid).

In contrast, the (A1) battery of the present invention,
(A2) The bulk density of each battery is 0.33g/c
m 3 , 0.28 g/cm 3 and is small, and is not doped with protonic acid (perchloric acid), so
The discharge capacity becomes significantly larger. From the above results, it was recognized that the addition of protonic acid is effective when the bulk density is high, but when the bulk density is low, the discharge capacity is rather small.

[0047] The (A1) battery and (A2) battery of the present invention
When the film-like polyaniline of the battery and Comparative Examples (X1) battery to (X3) battery was examined after the above test, it was found that:
It was confirmed that all film-like polyaniline was not substantially dissolved in the electrolyte.

[0048]

As explained above, according to the present invention, the solubility of the polyaniline porous film in organic solvents is reduced, so that it is possible to improve the reliability of a secondary battery using the polyaniline porous film, and Since the permeability of the electrolyte is improved without reducing the film strength, excellent effects such as high productivity and a secondary battery with a large discharge capacity can be obtained.

Claims (1)

[Claims] 1. A secondary battery comprising a positive electrode, an electrolyte, and a negative electrode made of a polyaniline porous film, wherein the polyaniline porous film is dried without doping with protonic acid, and is dehydrated. A secondary battery characterized in that the secondary battery is doped and has a bulk density of 0.1 to 0.9 g/cm3.