JP2001240730A - Conductive polythiophene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polythiophene high in electroconductivity. SOLUTION: The polythiophene is manufactured by deping bis(perfluoro- alkanesulfonyl)imide anions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polythiophene having a dopant anion.

[0002]

2. Description of the Related Art As one of conductive polymers having a structure in which a one-dimensional π-electron conjugate system continues for a long time, polythiophene having a sulfur atom in a molecule is known. Polythiophene is an organic functional material having high conductivity and excellent thermal stability, and its properties are being studied for various applications such as capacitors, batteries, and electrochemical capacitors. Generally, when a conductive polymer is used as a material for various devices, if the electric conductivity is low, the internal resistance of the device increases, so that it is preferable to have a higher electric conductivity. As one of means for increasing the electric conductivity of a conductive polymer, a method of adding a dopant is known. For example, Synthetic Metals, 74, 233
(1995) reported that electropolymerization of 3-methylthiophene was carried out in the presence of bis (trifluoromethanesulfonyl) imide.
s, 92, 57 (1998), it has been reported that 3,4-ethylenedioxythiophene was subjected to electrolytic polymerization. No indication is given for application to other monomers. Thus, when the dopant not only affects the electrical conductivity of the conductive polymer doped with it, but also affects the reaction behavior during polymerization and the solubility and thermal stability of the obtained conductive polymer. There is. Therefore, it was unclear whether a conductive polymer having a high electric conductivity could be obtained when the imides were applied to other monomers or polymerization methods other than the electrolytic polymerization method.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a polythiophene having higher electric conductivity.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve this problem, and as a result, succeeded in obtaining polythiophene having high electric conductivity by doping with a specific fluoride. That is, the gist of the present invention resides in polythiophene doped with a bis (perfluoroalkanesulfonyl) imide anion and / or a tris (perfluoroalkanesulfonyl) methide anion.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polythiophene of the present invention can be obtained by converting polythiophene into bis (perfluoroalkanesulfonyl) imide represented by the following general formula (1), tris (perfluoroalkanesulfonyl) methide represented by the following general formula (2) and / or It is obtained by doping a corresponding anion using these salts.

[0006]

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(In the formula, Rf, Rf ′ and Rf ″ each independently represent a perfluoroalkyl group.) Specific examples of the bis (perfluoroalkanesulfonyl) imide represented by the general formula (1) include: Examples thereof include bis (trifluoromethanesulfonyl) imide, bis (pentafluoroethanesulfonyl) imide, pentafluoroethanesulfonyltrifluoromethanesulfonylimide, trifluoromethanesulfonylheptafluoropropanesulfonylimide, and nonafluorobutanesulfonyltrifluoromethanesulfonylimide. Also,
When a salt of bis (perfluoroalkanesulfonyl) imide is used, specific examples of the counter cation include alkali metal cations such as lithium, sodium, potassium, and cesium; tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium;
Triethylmethylammonium, tetraethylammonium, tetrabutylammonium, N, N-dimethylpyrrolidinium, N-ethyl-N-methylpyrrolidinium, N, N-dimethylpiperidinium, N-ethyl-N
-Methylpiperidinium, tetramethylphosphonium,
Onium cations such as tetraethylphosphonium, 1-ethyl-2-methylimidazolium, 1-ethyl-2,3-dimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium and the like can be mentioned.

In the present invention, instead of bis (perfluoroalkanesulfonyl) imides, tris (perfluoroalkanesulfonyl) methides of the general formula (2) and / or salts thereof having similar properties may be used. Specific examples thereof include tris (trifluoromethanesulfonyl) methide, tris (pentafluoroethanesulfonyl) methide, and salts thereof. The cationic species forming the salt are the same as described above. The amount of the bis (perfluoroalkanesulfonyl) imide anion or the like to be doped into the polythiophene of the present invention is preferably 10 to 50 mol% based on the thiophene monomer. If the doping amount is smaller than the above range, the conductivity is lowered, which is not preferable. On the other hand, when the doping amount is larger than the above range, the conductivity is lowered, but the doping amount is about 100 mol%.
Polythiophenes to the extent of the extent can be included in the present invention.

Bis (perfluoroalkanesulfonyl)
The method of doping the polythiophene with an anion of an imide is not particularly limited, and an electrolytic polymerization method, a doping method, or the like can be employed. However, an oxidizing agent and bis (perfluoroalkanesulfonyl) imide, tris (perfluoroalkane) A chemical polymerization method of polymerizing thiophene in a solution containing sulfonyl) methide and / or a salt thereof is particularly preferred because mass production is possible.
Specific examples of the oxidizing agent used at the time of chemical polymerization in the present invention include peroxides such as ammonium peroxodisulfate, potassium peroxodisulfate, and hydrogen peroxide, and salts thereof;
Trivalent iron compounds such as iron (III) sulfate and iron (III) chloride; divalent copper compounds such as copper (II) sulfate and copper (II) nitrate; cerium (IV) sulfate and cerium (IV) fluoride , Cerium perchlorate (IV),
Tetravalent cerium compounds such as cerium (IV) hydroxide, cerium (IV) oxide, cerium (IV) trifluoromethanesulfonate, and cerium (IV) p-toluenesulfonate; quinone compounds such as chloranil; . Among them, peroxodisulfate and trivalent iron compound having relatively strong oxidizing power are preferable.

Specific examples of the solvent for the polymerization reaction used in the present invention include water, methanol, ethanol, isopropanol, n-butanol, acetonitrile, acetone,
Methyl ethyl ketone, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolan, propylene carbonate,
N, N-dimethylformamide, N, N-diethylformamide, N-methylformamide, formamide, N
-Methylpyrrolidinone, dimethylacetamide, hexamethylphosphoric triamide, dimethylsulfoxide, sulfolane, γ-butyrolactone, tetramethylurea, dichloroethane, dichloromethane, nitromethane, nitrobenzene, 2,2′-thiodiethanol. These can be used alone or as a mixture of two or more. The chemical polymerization method comprises bis (perfluoroalkanesulfonyl) imide or a salt thereof,
It is carried out by dissolving in advance the thiophene monomer and / or oxidizing agent solution and adding the oxidizing agent (solution) to the monomer solution, or adding the monomer (solution) to the oxidizing agent solution and polymerizing. You. The charged molar ratio of the monomer and the oxidizing agent is preferably in the range of 1: 0.1 to 1:10. The charging molar ratio of the oxidizing agent to bis (perfluoroalkanesulfonyl) imide or a salt thereof is 1:
The range of 0.1 to 1:10 is preferred. Reaction temperature is -78
The reaction temperature is preferably in the range of 1 to 12 hours, although it varies depending on the reaction temperature.

Thus, the bis (perfluoroalkanesulfonyl) imide anion is doped in an amount of about 10 to 100 mol%, preferably 10 to 50 mol%, and has an electric conductivity of about 1%.
Polythiophenes of １００100 S / cm are obtained. The polythiophene of the present invention has a high electric conductivity. Therefore,
When the polythiophene obtained by the present invention is used as an electrode material, it is possible to manufacture a device having a smaller internal resistance than before, and it is expected that the device characteristics such as charge and discharge characteristics are improved. The polythiophene of the present invention is preferably used for batteries, electrolytic capacitors, electrochemical capacitors and the like, and a schematic diagram of them is shown in FIG. The method for manufacturing these devices is not particularly limited, and various known methods are applied. For example, when manufacturing an electrode of a battery or the like, the polythiophenes of the present invention obtained as a powder,
By preparing a solution dissolved or finely dispersed in an appropriate solvent and performing a casting process such as spin coating using the solution, a film-like electrode of polythiophenes adhered to the substrate can be formed. Specific examples of solvents that dissolve or finely disperse the polythiophenes used in the present invention include cyclic carbonyl compounds such as N-methylpyrrolidinone, propylene carbonate, and γ-butyrolactone; aromatic compounds such as toluene and m-cresol; chloroform; Halogenated hydrocarbons such as carbon tetrachloride; ketones such as acetone and methyl ethyl ketone; alcohols such as ethanol, methanol and ethylene glycol; and water. Also, a sheet-like or pellet-like electrode can be formed by kneading and molding a conductive auxiliary such as acetylene black and a binder such as poly (tetrafluoroethylene) and poly (vinylidene fluoride).

[0012]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist of the invention. In addition, in the following examples, the electric conductivity was measured by the four short needle method. Example 1 1.68 g (20.0 mmol) of thiophene and 2.87 g (10.0 mmo) of lithium bis (trifluoromethanesulfonyl) imide
l) was dissolved in acetonitrile (100 ml) and stirred at room temperature. As an oxidizing agent, 8.11 g of iron (III) chloride (50.0 g
(mmol) was added and stirred for 12 hours. The resulting black fine precipitate was collected by filtration, washed with water and acetone, and dried under reduced pressure to obtain polythiophene 0.80.
g was obtained. In addition, elemental analysis confirmed that 30 mol% of bis (trifluoromethanesulfonyl) imide anion was doped. The electric conductivity of the obtained polythiophene showed a high value of 15 S / cm.

Comparative Example 1 Thiophene was polymerized in the same manner as in Example 1 using iron (III) chloride without using bis (perfluoroalkanesulfonyl) imide. The electric conductivity of the obtained polythiophene was as low as 10 S / cm.

Example 2 (Production of an electrolytic capacitor) Aluminum foil (thickness: 70 μm, area: 1 × 1 cm, capacitance: 25 μF / cm) treated to enlarge the surface by etching
² ) was applied in an aqueous solution of 10% by weight of ammonium adipate to apply a voltage of 40 V to form an oxide film serving as a dielectric on the surface of the aluminum foil. Subsequently, the polythiophene obtained in Example 1 was dispersed in N-methylpyrrolidinone and applied, and then the solvent was distilled off by drying under reduced pressure at 50 ° C. This was repeated four times to form a cathode layer made of polythiophene. A carbon paste and a silver paste were sequentially applied as a conductive paste to this, and a cathode lead was connected to obtain a solid electrolytic capacitor. When the electrical characteristics of this solid electrolytic capacitor were measured using an LCR meter, 12
The capacitance and dielectric loss at 0 Hz are 24
The equivalent series resistance at μF and 0.9%, 100 kHz was 5Ω. The solid electrolytic capacitor using this polythiophene has excellent impedance characteristics because of its low dielectric loss and low equivalent series resistance in a high frequency band.

[0015]

According to the present invention, a polythiophene having a high electric conductivity can be produced by a chemical polymerization method capable of mass production, so that a battery and an electrochemical capacitor having excellent device characteristics can be produced using the polythiophene. , An electrolytic capacitor and the like can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view of various devices using a conductive polymer.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01M 4/60 H01G 9/02 331G (72) Inventor Makoto Ue 8-3-1 Chuo, Ami-cho, Inashiki-gun, Ibaraki Mitsubishi F-term in the Tsukuba Research Laboratories (Reference) 4J002 CE001 EV246 EV266 GQ00 5H050 AA12 CA20

Claims (3)

[Claims] 1. Bis (perfluoroalkanesulfonyl)
Polythiophene doped with an imide anion and / or a tris (perfluoroalkanesulfonyl) methide anion. 2. Bis (perfluoroalkanesulfonyl)
The polythiophene according to claim 1, wherein the imide is bis (trifluoromethanesulfonyl) imide or bis (pentafluoroethanesulfonyl) imide. 3. An electrode material using the polythiophene according to claim 1.