JPS6319763A - Battery - Google Patents

Abstract

PURPOSE:To increase conductivity and discharge capacity, or charge-discharge capacity by using conductive layer having high conductivity obtained by chemical oxidation-polymerization under coexistence with the same kind of anion as that constituting an oxidizing agent as an electrode. CONSTITUTION:A conductive polymer obtained by reacting a pyrrole compound indicated in the formula with an oxidizing agent under the existence of a compound having the same kind of anion as that constituting an oxidizing agent is used in an electrode. As the pyrrole compound, pyrrole, N-methyl pyrrole, or N-ethyl pyrrole is used, As the oxidizing agent, a metal salt having strong acid residue, halogen, or cyanogen, or peroxide such as Fe(ClO4)3, Fe(BF4)3, and Fe2(SiF6)3 is used.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a battery using a conductive polymer as an electrode.

<Prior art> Polymers having co-1Q double bonds in their main chains, such as polyacetylene, polyparaphenylene, polythenylene, polypyrrole, and polyparaphenylenevinylene, are made of arsenic pentafluoride,
Antimony pentafluoride.

When treated with P-type or N-type doping agents such as iodine, bromine, sulfur trioxide, n-butylridium, and sodium naphthalene, the electrical conductivity can be significantly improved, allowing the material to change from an insulator to a semiconductor or even a conductor. Are known.

These conductive materials (so-called conductive polymers) are in the form of a single powder.

An antistatic material that can be obtained in the form of lumps or films, and can be used as is or after being molded depending on the purpose.

Functional elements such as electromagnetic wave shielding materials, photoelectric conversion elements, optical memory (holographic memory), various sensors, display elements (electrochromism), switches, various hybrid materials (transparent conductive films, etc.), various terminal equipment,
Applications to a wide range of fields such as secondary and secondary batteries are also being considered.

-And if we take as an example the case where a secondary battery is constructed using polyacetylene among the conductive polymers mentioned above as an electrode,
Polyacetylene is used for at least one of the positive electrode and the negative electrode, and BF4-1CnuO"', SbF-1PF
anidine such as 6-, or Ll, Na, R4N
(R represents an alkyl group), etc., is electrochemically reversibly doped and undoped to cause a charge/discharge reaction.

By the way, among these conductive polymers, polypyrrole has advantages such as good stability in air, extremely little oxidative deterioration, and ease of handling compared to, for example, polyacetylene. Therefore, when polypyrrole is used as a battery electrode, it is possible to produce an electrode that is easier to produce and has better storage stability and battery characteristics than polyacetylene.

Conventionally known examples of such polypyrrole include (1) pyrrole produced by electrochemical oxidative polymerization (electrolytic polymerization), and (2) pyrrole produced by chemical oxidative polymerization of pyrrole using an oxidizing agent. In the case of (2), polypyrrole is deposited in the form of a film on the electrolytic anode plate, and after being deposited, the film-like polypyrrole is peeled off from the plate. In the case of ■, peroxides such as potassium persulfate and ammonium persulfate, acids such as nitric acid, sulfuric acid, or chromic acid, Lewis acids such as iron chloride, ruthenium chloride, tungsten chloride, or molybdenum chloride are used as the oxidizing agent. Powdered polypyrrole was obtained by oxidative polymerization.

However, among these conventional polypyrroles, the above
The one is ′! The A-manufacturing method is complicated and not only causes high battery costs, but since polypyrrole is produced on the electrolytic anode plate, the shape and size of the polypyrrole obtained are restricted by the dimensions of the plate, which makes mass production difficult. It also has the disadvantage that it is difficult to use industrially due to major limitations in terms of aspects.

On the other hand, when the polypyrrole obtained in the above (2) is used, there is no such drawback. However, since this polypyrrole has few doping factors during oxidative polymerization, its electrical conductivity is extremely low, and when a battery is made using it as an electrode, the internal resistance of the battery increases or in the case of a secondary battery. There are disadvantages such as poor battery characteristics and low battery capacity because the charging and discharging reactions are uneven in each part of the electrode.

In an attempt to increase the electrical conductivity of conductive polymers produced by chemical oxidative polymerization, for example, the oxidizing agent used in oxidative polymerization has the general formula FeX (where X is CJ2'O-
1BF4-1mn 4 ASF -1PF -1SbF6-1zrF6-1
T 1F6-or S! represents F6-, m and n are 1
Represents an integer from ~3. It has been proposed to use a ferric compound represented by In addition, since it is possible to increase the conductivity of this type of conductive polymer by doping it with a dopant, conductive polymers produced by chemically polymerizing do not require a separate doping treatment after oxidative polymerization. It is also possible to increase the electrical conductivity of Furthermore, by increasing the concentration of the oxidizing agent used in polymerization, the reaction rate during polymerization can be increased, and the amount of dopant doped at this time can be increased to increase the @electricity of the chemically oxidatively polymerized polymer. Be expected.

<Problems to be Solved by the Invention> However, when a ferric compound is used as an oxidizing agent as described above, although it is possible to provide a conductive material with considerably high electrical conductivity, the resulting conductive material The electrical conductivity of polymers is still insufficient for practical use.

Further, when a separate doping treatment is performed, a step of doping treatment is required, which makes the manufacturing method complicated and increases the cost.

Furthermore, if the concentration of the oxidizing agent used for polymerization is increased, although the above problems do not occur, there is a risk that the polymerization reaction will not occur uniformly in each part of the polymer, resulting in uneven doping rates in each part of the resulting polymer. In addition, there is a problem that the polymerization reaction becomes too vigorous, resulting in deterioration of the quality of the polymer in some parts.

By the way, as disclosed in JP-A No. 60-58430, for example, pyrrole-based oxidants are oxidized in a solution using an oxygen-containing oxidizing agent in the presence of a conductive salt having an anion different from the anion constituting the oxidizing agent. Attempts have also been made to polymerize compounds.

According to this technique, it is possible to increase the number of seedlings of Dopan 1 to be doped during polymerization without increasing the oxidizing agent concentration, and a polymer with high electrical conductivity can be obtained.

However, since this conductive polymer is doped with multiple types of dopants: an anion constituting the oxidizing agent and an anion constituting the conductive salt, when this polymer is used as a battery electrode, Seed electrode reactions occur, resulting in disadvantages such as a two-stage discharge curve or charge/discharge curve.

<Means for Solving the Problems> The battery of the present invention has a general formula (wherein R and R2 are hydrogen atoms, alkyl groups, alkoxy groups, aryl groups, allyloxy groups, alkylthio groups, amino groups, halogen atoms, a cyano group or a nitro group, and R3 represents a hydrogen atom, an alkyl group, or an aryl group. The gist is that the conductive polymer obtained by the reaction described below was used for at least one electrode.

Among the pyrrole compounds represented by the above general formula, pyrrole compounds having no substituents at the 2 and 5 positions of the pyrrole ring skeleton structure are preferred.

In addition, in detail, R1-R2 are hydrogen atoms, methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, sec-butyl groups, tert-butyl groups, methoxy groups, ethoxy groups, n-propoxy group,
Isopropoxy group, n-butoxy group, phenyl group, tolyl group, naphthyl group, phenoxy group, methylphenoxy group, naphthoxy group, methylthio group, ethylthio group, amino group, fluorine atom, chlorine atom, bromine atom, iodine atom, cyano group, nitro group, R3 represents a hydrogen atom, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, 5ec-butyl group, tert-
Represents a butyl group, a phenyl group, a tolyl group, and a naphthyl group.

Specific examples of such pyrrole compounds include pyrrole, N-methylpyrrole, N-ethylpyrrole, and N-
Phenylpyrrole, 3-methylpyrrole, N-methyl-
3-methylpyrrole, 3-chloropyrrole, 3,4-dichloropyrrole, 3-bromopyrrole, N-methyl-3
-bromopyrrole, 3-methoxypyrrole, 3-phenoxypyrrole, 3-phenylpyrrole, 3-methylthiopyrrole, 3-ethylthiopyrrole, 3-aminopyrrole, 3-nitropyrrole, N-phenyl-3-methylpyrrole, N -naphthyl-3-methylpyrrole and the like.

The above-mentioned oxidizing agent is a compound having polymerization activity toward the above-mentioned pyrrole compound, and may be used alone or in combination of two or more. Usually, metal salts with strong acid residues, halogens, and cyanide.

Peroxides etc. are used, specifically, Fe (CJ204 > 3, Fe (E3F4 > 3゜Fe2 (S! R6) 3, Cu (CJ2
04 >, 2°Cu (BF4)2. CuS! R
6, FeCl3.

CuCff12, K3 (Fe (CN)6).

RuC,g3, MoC,ff5, WCff16
.

(N H4) 23206, K232 OB.

N82320H, NaBO3, H202, etc.
Those containing water of crystallization or those obtained as an aqueous solution can also be used.

Specifically, the coexisting compounds having the same type of anion as the anion constituting the oxidizing agent include iCλ04, L IBF4, and L! As
F6.

LiPF6. L! SbF6. L12 ZrF6゜shi12
TiF6. Li2SiF6. LiCbu.

L i 303 C6H4CH3, L l 2810C
J10゜L12B12Cbu12. LrCF35o3゜L
Examples include iAβCbu4.

The amount of these coexisting compounds used is 0.01 to the oxidizing agent.
It is used in an amount of up to 100 times the mole, preferably 0.1 to 50 times the mole.

The reaction product is a dark brown to black powdery substance, and in the case of the reaction in the presence of the above solvent, after the reaction is completed, the solvent must be removed in the usual manner, or the product can be collected by transferring it to water, alcohol, etc. Can be done.

This reaction product has electrical conductivity as described in the Examples. In the present invention, the reaction product is molded into a desired shape by a known method such as pressure molding, and used as an electrode for a battery. At this time, it is possible to use such a reaction product alone, but in order to increase the mechanical strength of the electrode and increase the conductivity to improve battery characteristics, thermoplastic resin or an appropriate conductive material may be used. It is preferable to add the like. As such a thermoplastic resin, any thermoplastic resin can be used without particular limitation as long as it is substantially insoluble in the electrolyte of the battery. Usually, those with a molecular weight of 10,000 or more are used,
Specific examples include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-tetrafluoroethylene copolymer, polytetrafluoroethylene, polytrifluoroethylene, polydifluoroethylene, tetrafluoroethylene perfluoroalkyl vinyl ether Copolymer.

Tetrafluoroethylene-hexafluoropropylene copolymer, polytrifluorochloroethylene, polynylidene fluoride, tetrafluoroethylene-ethylene copolymer, chlorotrifluoroethylene-ethylene copolymer, polyamide, polyester, polycarbonate, and modified polyolefins.

The conductive member is not particularly limited as long as it is made of metal such as stainless steel, gold, platinum, nickel, copper, molybdenum, titanium, carbon, carbon fiber, etc. Preferably a sexual one.

Specifically, metal nets made of such metals, metal-plated fibers, metal-vaporized fibers, metal-containing synthetic fibers,
In addition, examples include nets, woven fabrics, and nonwoven fabrics made of iui, carbon fibers, carbon composite fibers, and the like.

The addition of such thermoplastic resin and conductive material is a reaction product (thermoplastic @ for organic semiconductor > 10011 parts).
It is preferable to use 0.02 to 1000 parts by weight of the fat and 2 to 100 parts by weight of the conductive member.

In the battery of the present invention, there are cases in which electrodes made of such reaction products as electrode materials are used for both the positive and negative electrodes, and cases in which this electrode is used only for one electrode, and metal or fully oxidized electrodes are used for the other electrodes. In some cases, known conductive polymers, organic compounds, organometallic compounds, etc. other than the reaction products of the present invention may be used as electrode materials. For example, if an electrode using this reaction product is used only for the positive electrode, and a metal is used as the negative electrode material,
It is preferable to use a metal having an electronegativity of 1.6 or less as the metal constituting the negative electrode, and examples of such metals include l-i and Na.

K, MO, AJ! Or alloys thereof, etc.
Li and li-gold alloys are preferred.

On the other hand, as the electrolytic solution used in the battery of the present invention, for example, a solution in which an electrolyte is dissolved in an organic solvent is used. Examples of the electron Wt* include salts with cations and anions such as metal cations and organic cations having an electronegativity of 1.6 or less. Examples of onium ions include quaternary ammonium ions, carbonium ions, ogisonium ions, and the like. In addition, as anions, BF -1Cλ04-1PF6-, ASF
-, CF3303-, l-1Br-1Cλ-1F'', etc. Specific examples of such electrolytes include lithium tetrafluoroborate (LiBF4),
Lithium perchlorate (L r cβ04), lithium hexafluorophosphate (LiPF6), lithium tetrachloroaluminate (LiAλC24), tetraethylammonium tetrafluoroborate (Et NBF4), tetran-butyperchlorate)'v? ”, / -E Ni (nBu4NCβ04), lithium trifluoromethanesulfonate (L i CF3 SO3), lithium iodide nir
>, lithium bromide (Liar), etc., but are not limited to these. Taking as an example a secondary battery that uses the conductive polymer of the present invention in both the positive and negative electrodes and uses an electrolyte in which LiBF4 is dissolved as an electrolyte, during charging, the electrolyte is applied to the organic semiconductor in the positive electrode. The BF4- inside is doped, and the organic semiconductor inside the negative electrode is doped with Ll in the electrolyte. On the other hand, during discharge, BF-1L+ doped into the positive and negative electrodes is released into the electrolyte, respectively.

In addition, as the leading solvent for dissolving the electrolyte, it is preferable to use a high dielectric constant aprotic solvent, such as nitrile, carbonate, ether, nitro compound, amide, sulfur-containing compound,
Chlorinated hydrocarbons, ketones, esters, etc. can be used. Moreover, two or more kinds of such solvents can also be used in combination. Representative examples of these include acetonitrile, propionitrile, butyronitrile, benzonitrile, propylene carbonate, ethylene carbonate,
Tetrahydrofuran, dioquinrane, 1,4-dioxane, nitromethane, N,N-dimethylformamide, dimethyl sulfoxide, sulfolane, 1,2-dichloroethane, γ-butyrolac 1-one, 1,2-dimethoxyethane, methyl phosphate, phosphoric acid Examples include, but are not limited to, ethyl.

The Q degree of the electrolyte of the present invention is usually 0.001 to
Used at 10 mol/β, preferably 0.1 to 3 mol/β
Used in β.

In addition to being injected, such an electrolytic solution can also be used by pre-impregnating an electrode using the conductive polymer of the present invention.

Further, in the present invention, in order to fix the electrode in the electrolyte, the electrode may be covered with a slat-like or holed glass, Teflon, polyethylene, plate, or the like.

Further, in the battery of the present invention, a porous membrane such as glass filter paper, Teflon, polyethylene, polypropylene, nylon, etc. may be used as the separator.

<Function> When a pyrrole compound is chemically polymerized using an oxidizing agent, a reaction in which an anion constituting the oxidizing agent is doped into the produced polymer occurs simultaneously during this polymerization reaction.

At that time, by coexisting with the oxidizing agent a compound consisting of the same type of anion as the above-mentioned anion constituting the oxidizing agent, a reaction occurs in which the anions in this compound are also doped into the produced polymer, and the oxidizing agent Since the G degree of the anion is higher than when only the anion is present, doping proceeds extremely smoothly, and doping is uniform in each part of the monomer.

Therefore, the conductive polymer obtained by the above method is more fully doped with the dopant than the conductive polymer obtained by chemically polymerizing in the presence of only an oxidizing agent. Practically sufficient electrical conductivity can be obtained even without applying.

In addition, since this conductive polymer is doped with one type of dopant, when used as a battery electrode, there is only one type of electrode reaction, and the discharge curve or charge/discharge curve becomes one step. Since the doping rate of the dopant is high, the discharge or charge/discharge capacity becomes the largest.

<Example> The present invention will be explained in detail by giving examples below.

Manufacturing Example 1 of Conductive Polymer 74.9 g (0
, 15 mol> and i6 g (0.15 mol> each of LiC2O4 as a coexisting compound, and 600 g
Add mu and dissolve while stirring under nitrogen atmosphere.

To this aqueous solution, 10.1q of pyrrole was added dropwise at room temperature (25°C) under a nitrogen stream.The reaction solution turned black as the dropwise addition was continued, and after continued stirring for 2 hours, it was left at room temperature overnight. A powdery precipitate was observed at the bottom of the reaction solution. After filtration, the residue was washed three times with 200 μl of methanol, and then washed twice with 200 μl of water and 200 μl of toluene.
Washing was repeated twice with m9 and twice with methanol 200n+J). After washing and drying at 60'C under reduced pressure, 8.
A black powdery substance of 0 ( ) was obtained.

The electrical conductivity of this reaction product (polypyrrole) was measured and found to be 7.53 cm'.

Comparative Production Example 1 of Conductive Polymer Also, an experiment was conducted in the same manner as Production Example 1 above except that LiC2O4 was not added, and the electrical conductivity was 7.6 x 1.
The reaction product (polypyrrole) of 0-2S cm-1 (
It was.

From the above results, it is clear that L r cflo4 is the oxidizing agent F
It was found that polypyrrole having about 100 times higher electrical conductivity was produced when this oxidizing agent was used together with e(C40)-8)-120 than when this oxidizing agent was used alone.

Comparative Production Example 2 of Conductive Polymer Furthermore, LiBl was used as a coexisting compound. An experiment was conducted in the same manner as in Production Example 1 above except that Cλ1o was used, and the electrical conductivity of the IQ polypyrrole was 7.03 C.
I missed it on m-1.

Incidentally, in the above three production examples, the electrical conductivity was measured as follows. That is, first, the polypyrrole obtained by the above treatment was ground sufficiently finely in a mortar, and then
It was press-molded (5 tons/Cll2) into a disk shape of m.

Next, this disk sample was sandwiched between two copper cylinders of the same size, a pressure of 1.2 KiJ was applied from the top, and the conductor leads were taken out from the upper and lower copper cylinders and placed in a digital multimeter (
The electrical conductivity of the disk sample was measured by connecting it to a TR6851 (manufactured by Takeda Risensha).

Battery Example 1 The polypyrrole obtained in Production Example 1 above was used as the positive electrode, lithium metal was used as the negative electrode, and lithium perchlorate (electrolyte) was dissolved in a mixed solvent of propylene carbonate and dimethoxyethane as an electrolyte. A primary battery (Battery A) according to the present invention was manufactured using the same. In addition, a comparative primary battery (Battery B) was produced in the same manner as in Comparative Production Example 1 except that polypyrrole 18 was used for the positive electrode.Furthermore,
A primary battery for comparison (Battery C
) was created. FIG. 1 shows the structures of these batteries A to C. In the figure, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator, 4 is a positive electrode can, and 5 is a negative electrode can.

FIG. 2 shows the change in battery voltage (V) with respect to discharge sound i (mAH) when the above three batteries were discharged with a current of 1 m until the battery voltage reached 2.5V.

From the figure, the discharge curve of battery A according to the present invention is smooth, while battery C, which uses polypyrrole obtained by polymerizing an anion constituting the oxidizing agent and a compound having a different type of anion, coexists. It can be seen that the charge/discharge curve of is in two stages. Furthermore, battery B, which uses polypyrrole polymerized in the presence of only an oxidizing agent, has a lower discharge capacity than batteries A and C. The reason why battery B has such a low discharge capacity is that the amount of dopant in the polypyrrole used in battery B is small.

Battery Example 2 The polypyrrole produced in Production Example 1 above was used as the positive electrode, lithium metal was used as the negative electrode, and an electrolytic solution prepared by dissolving lithium perchlorate in a mixed solvent of propylene carbonate and dimethoxyethane was used as the negative electrode. Thus, a secondary battery (Battery D) according to the present invention was manufactured. In addition, a secondary battery for comparison (Battery E
, F) was produced. Note that the battery structures of batteries D to F are the same as those of batteries A to C described above.

The above three batteries D-F were charged with a current of 1 mA for 4 hours, and then discharged with a current of 1 mA until the battery voltage reached 2.5V. FIG. 3 shows the change in battery voltage with respect to the change in charging/discharging sound i (mAtl) at this time. From the same figure, in the case of battery F, which uses polypyrrole polymerized in the coexistence of an anion constituting the oxidizing agent and a compound having a different type of anion as the positive electrode, the battery voltage changes during charging and discharging are both two-stage. I know that there is. This is because the two types of dopants present in the positive electrode have different doping potentials and dedoping potentials. In addition, in the case of battery F,
When the battery was charged to 3 mAH, the battery voltage was 5.0V.
Therefore, further charging could not be carried out because of problems such as deterioration of the polypyrrole.

The reason why such a voltage increase was observed when battery F was charged is thought to be due to the low electrical conductivity of the polypyrrole used as the positive electrode and the high internal resistance of the battery. It was not possible to do so, and the discharge capacity became small. On the other hand, in the case of the battery according to the present invention, the battery voltage changes smoothly during both charging and discharging, and the charging and discharging capacity is also large.

<Effects of the Invention> According to the battery of the present invention constructed as described above, the electrical conductivity is increased by chemically oxidizing and polymerizing a compound having 7 anions of the same type as the anion constituting the oxidizing agent. Since a large conductive polymer is used for the electrode, the conductivity of the electrode is increased to a practical level, and a battery with excellent characteristics, which has a large discharge or charge/discharge capacity, can be provided.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the structure of a battery such as a battery according to an embodiment of the present invention, Fig. 2 is a graph showing changes in battery voltage with respect to discharge capacity of a battery etc. of an embodiment, and Fig. 3 is a graph showing the change in battery voltage with respect to the discharge capacity of the battery of the embodiment. It is a graph showing changes in battery voltage with respect to capacity. 1...Positive electrode, 2...Negative electrode, 3...Separator. Patent applicant Mitsubishi Chemical Industries, Ltd. Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R^1 and R^2 are hydrogen atoms, alkyl groups, alkoxy groups, aryl groups, allyloxy groups, alkylthio groups, represents an amino group, a halogen atom, a cyano group, or a nitro group, and R^3 represents a hydrogen atom, an alkyl group, or an aryl group) and an oxidizing agent, and an anion constituting the oxidizing agent. A battery characterized in that a conductive polymer obtained by reaction in the presence of a compound having the same type of anion is used for at least one electrode.