JP2010044951A - Electrode active material and electrode using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode active material capable of attaining an electrochemical element having high capacity and high energy density. <P>SOLUTION: The electrode active material is composed of: fluorene-thiophene alternating copolymer in which fluorene ring is bonded to thiophene ring substantially at the 2- and 7-positions of the fluorene ring and the thiophene ring is bonded to the fluorene ring substantially at the 2- and 5-positions of the thiophene ring; or fluorene-2,2'-bithiophene alternating copolymer in which fluorene ring is bonded to 2,2'-bithiophene ring substantially at the 2- and 7-positions of the fluorene ring and the 2,2'-bithiophene ring is bonded to the fluorene ring substantially at the 5- and 5'-positions of the 2,2'-bithiophene ring. The electrode active material has considerably-increased capacity in comparison with an electrode active material composed of bulk-polymerized polyfluorene polymerized at an irregular position, obtained by polymerization using ferric chloride (III) as a catalyst. Therefore, the electrochemical element having high capacity and high energy density can be obtained by using this electrode active material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode active material capable of providing an electrochemical element having a high capacity and a high energy density, and an electrode using the electrode active material.

  Expectations for low-emission vehicles such as electric vehicles and hybrid vehicles to replace gasoline and diesel vehicles from the viewpoint of reducing oil consumption, mitigating air pollution, and reducing emissions of carbon dioxide, which causes global warming. It is growing. As a motor drive power source in such a low pollution vehicle, an electrochemical element such as a secondary battery or an electric double layer capacitor having a high energy density and a high output density is used.

  Secondary batteries include batteries using an aqueous electrolyte and batteries using a non-aqueous electrolyte (organic electrolyte).

  Examples of batteries using acidic or alkaline aqueous electrolyte include lead batteries, nickel / cadmium batteries, nickel metal hydride batteries, and proton batteries. Since these secondary batteries have an electrolysis voltage of water of 1.23 V, a higher operating voltage cannot be obtained. As a power source for an electric vehicle, a high voltage of about 200V is required. To obtain this voltage, many batteries must be connected in series, which is disadvantageous for reducing the size and weight of the power source. is there. However, since the aqueous electrolyte has high ionic conductivity, it has excellent output characteristics that a large current can be obtained during charging and discharging.

On the other hand, lithium ion secondary batteries are well known as batteries using nonaqueous electrolyte solutions. In general, this battery uses a carbon material that occludes and releases lithium ions as a negative electrode, a lithium layered compound such as lithium cobaltate (LiCoO ₂ ) as a positive electrode, and a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ). A solution dissolved in an organic solvent such as ethylene carbonate or propylene carbonate is used as an electrolytic solution. Since such a lithium ion secondary battery has a high electrolysis voltage of the organic solvent, 3.6 V can be obtained as an average operating voltage, and the energy density is also high. However, since the charge / discharge reaction is occlusion and release of lithium ions in the electrode, the output characteristics are inferior, and it is disadvantageous as a power source for an electric vehicle that requires a large instantaneous current.

  The electric double layer capacitor uses a polarizable electrode such as activated carbon as positive and negative electrodes, and uses an electric double layer generated at the interface between the electrode surface and the electrolytic solution as a capacitance. An electric double layer capacitor has a high output density, can be rapidly charged and discharged, and has little capacity deterioration even after repeated charging and discharging. This is because in an electric double layer capacitor, electrolyte ions move only in the electrolytic solution along with charging / discharging and are adsorbed / desorbed to / from the electrode interface, and do not involve an electrochemical reaction as in a battery.

  Also in the electric double layer capacitor, there are a capacitor using an aqueous electrolyte and a capacitor using a non-aqueous electrolyte (organic electrolyte).

  Since the operating voltage of an electric double layer capacitor is mainly determined by the electrolysis voltage of the electrolyte, the capacitor using an aqueous electrolyte has a higher operating voltage than the capacitor using a non-aqueous electrolyte (organic electrolyte). It is disadvantageous in terms. However, it has the advantage of high power density and safety.

  On the other hand, an electric double layer capacitor using a non-aqueous electrolyte solution in which a quaternary onium salt such as boron tetrafluoride or phosphorus hexafluoride is dissolved in an organic solvent such as propylene carbonate has an operating voltage of an aqueous electrolyte solution. It is higher than the capacitor, but lower than the secondary battery. In addition, the energy density due to the electric double layer capacity is lower than that of the secondary battery, and the power source of the electric vehicle is greatly insufficient.

  In order to improve such problems, studies on electrode active materials used in electrochemical devices are underway.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-297362) discloses a positive electrode mainly composed of a p-doped conductive polymer, a negative electrode mainly composed of a carbon material capable of inserting and extracting lithium ions, and a lithium salt. A hybrid secondary power source having an organic electrolyte solution is proposed. A secondary power source using a polythiophene having a weight average molecular weight of 50000, a poly (3-methylthiophene) having a weight average molecular weight of 80000, etc. as a positive electrode, an operating voltage of 4.0 V, and a secondary power source using activated carbon as a positive electrode A secondary power source having a capacity equal to or higher than that of the battery and having high charge / discharge cycle reliability is obtained.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 6-104141) discloses an electrolytic double layer for the purpose of increasing the capacity and reducing the internal resistance of an electric double layer capacitor having an electrode prepared using a conductive polymer powder paste. An electric double layer capacitor using a conductive polymer film obtained by a legal method as a polarizable electrode is proposed. By using the polypyrrole film obtained by the electrolytic polymerization method, an electric double layer capacitor having an operating voltage of 2.6 V and a higher capacity than an electric double layer capacitor having an electrode using a powder paste has been obtained.

  In order to improve the low energy density in the electric double layer capacitor, an electrochemical capacitor using an additional capacitance due to a redox reaction or a charge transfer reaction on the electrode surface in addition to the electric double layer capacitance has been studied. Yes. As an electrode active material for such an electrochemical capacitor, charge transfer by exchange of π-electrons with metal oxides such as ruthenium oxide, manganese oxide, nickel oxide, etc. where an oxidation-reduction reaction easily occurs, and anions and cations of electrolytes Conductive polymers such as polyaniline, polythiophene, polypyrrole and the like in which the above occurs relatively easily have been studied.

  Patent Document 3 (Japanese Unexamined Patent Publication No. 2000-315527) discloses a conductive polymer containing a thin film-like triphenylamine as a repeating unit as a positive electrode and a thin film-like 2,2′-bipyridine as a repeating unit. A non-aqueous electrochemical capacitor having a negative electrode made of a conductive polymer has been proposed, and a non-aqueous electrochemical capacitor exhibiting an operating voltage of up to 2.7 V and having an energy density more than three times that of an electric double layer capacitor has been obtained. Yes.

  Patent Document 4 (Japanese Patent Laid-Open No. 2006-48974) discloses an electrode material composed of polyfluorene or a derivative thereof, and the n-doped redox potential of the polyfluorene derivative is a conventional conductive polymer. The p-doped redox potential of polyfluorene or its derivatives is higher than that of conventional conductive polymers, indicating that this electrode material has high voltage characteristics. When poly (9,9-dimethylfluorene) obtained by polymerization using iron (III) chloride as a catalyst is used as an electrode active material, a secondary battery and an electrochemical capacitor using poly (3-methylthiophene) It shows that a secondary battery and an electrochemical capacitor having a higher operating voltage can be obtained.

Further, Patent Document 5 (Japanese Patent Laid-Open No. 2007-81384) discloses a pair of electrodes of an electrochemical capacitor using a non-aqueous electrolyte solution of carbon nanotubes containing semiconducting carbon nanotubes having a specific surface area of 700 m ² / g or more. When used as at least one of the above, when the semiconducting carbon nanotubes are polarized in contact with the electrolyte solution, p-doping and n-doping occur to increase the carrier density, improve the electric capacity, Since the specific surface area further increases the capacitance and energy density of the electrochemical capacitor, it is disclosed that an electrochemical capacitor having high electric capacity and high energy density and improved withstand voltage can be obtained.

JP 2003-297362 A JP-A-6-104141 JP 2000-315527 A JP 2006-48974 A JP 2007-81384 A

  However, there is a constant demand for miniaturization and weight reduction of motor drive power supplies for electric vehicles, etc. Therefore, there is a strong demand for higher operating voltage, higher capacity, and higher energy density for electrochemical elements used as power supplies. There is.

  Accordingly, an object of the present invention is to provide an electrode active material having a higher capacity than conventional conductive polymers and an electrode using the same, which can provide an electrochemical element having a high capacity and a high energy density. is there.

  The inventors proceeded with studies based on the electrode active material composed of polyfluorene disclosed in Patent Document 4, and in the production of an alternating copolymer composed of fluorene and monothiophene or bithiophene, fluorene and monothiophene or It has been found that the above-mentioned problems can be solved by carrying out the polymerization while precisely controlling the reaction point of bithiophene.

  The electrode active material of the present invention is first an electrode active material comprising at least one alternating copolymer composed of fluorene and thiophene, wherein the fluorene ring of the alternating copolymer is substantially in the 2-position. It is bonded to the thiophene ring at the 7-position, and the bonding positions of the thiophene ring to the fluorene ring are substantially the 2-position and 5-position. Hereinafter, the fluorene ring is bonded to the thiophene ring substantially at the 2nd and 7th positions, and the thiophene ring is composed of fluorene and thiophene whose bonding positions to the fluorene ring are substantially at the 2nd and 5th positions. The copolymer is referred to as “precision polymerized fluorene-monothiophene alternating copolymer”. The term “the fluorene ring is substantially bonded to the thiophene ring at the 2nd and 7th positions” is 90% or more, preferably 95% or more, more preferably 98% of the number of fluorene rings contained in the alternating copolymer. % Or more, particularly preferably 100% means that the fluorene ring is bonded to the adjacent thiophene ring at the 2nd and 7th positions. In addition, the term “the bonding positions of the thiophene ring with respect to the fluorene ring are substantially the 2nd and 5th positions” is 90% or more, preferably 95% or more, more preferably, of the number of thiophene rings contained in the alternating copolymer. It means that 98% or more, particularly preferably 100%, of the thiophene ring is bonded to the adjacent fluorene ring at the 2-position and 5-position.

  The electrode active material of the present invention is also an electrode active material comprising at least one alternating copolymer composed of fluorene and 2,2′-bithiophene, wherein the fluorene ring of the alternating copolymer is substantially In particular, it is bonded to the 2,2′-bithiophene ring at the 2nd and 7th positions, and the bonding position of the 2,2′-bithiophene ring to the fluorene ring is substantially at the 5th and 5 ′ positions. To do. Hereinafter, the fluorene ring is bonded to the 2,2′-bithiophene ring at the 2nd and 7th positions, and the bonding positions of the 2,2′-bithiophene ring to the fluorene ring are substantially at the 5th and 5 ′ positions. An alternating copolymer composed of fluorene and 2,2′-bithiophene is represented as “precisely polymerized fluorene-bithiophene alternating copolymer”. The term “the fluorene ring is substantially bonded to the 2,2′-bithiophene ring at the 2nd and 7th positions” is 90% or more, preferably 95% or more of the number of fluorene rings contained in the alternating copolymer. More preferably, it means that 98% or more, particularly preferably 100%, of the fluorene ring is bonded to the adjacent 2,2′-bithiophene ring at the 2nd and 7th positions. In addition, the phrase “the bonding positions of the 2,2′-bithiophene ring to the fluorene ring are substantially at the 5th and 5 ′ positions” is 90% of the number of 2,2′-bithiophene rings contained in the alternating copolymer. This means that preferably 95% or more, more preferably 98% or more, and particularly preferably 100% of 2,2′-bithiophene rings are bonded to adjacent fluorene rings at the 5 and 5 ′ positions.

  FIG. 1A shows a fluorene-monothiophene chain in a precision polymerized fluorene-monothiophene alternating copolymer as an electrode active material of the present invention, and FIG. 1B shows an electrode active material of the present invention. 1 shows a fluorene-bithiophene chain in a precisely polymerized fluorene-bithiophene alternating copolymer, and FIG. 1 (c) shows a polyfluorene obtained by polymerization using iron (III) chloride as a catalyst disclosed in Patent Document 4. The fluorene chain in is shown.

  In the polymerization using iron (III) chloride as a catalyst, it is difficult to control the reaction point, so that the growth direction becomes irregular as shown in FIG. Hereinafter, polyfluorene in which such a fluorene ring is polymerized at irregular positions is referred to as “bulk polymerized polyfluorene”, but since bulk polymerized polyfluorene has many branching sites and meta-conjugated sites. The charge utilization rate becomes low.

  In contrast, the precision polymerized fluorene-monothiophene alternating copolymer shown in FIG. 1A and the precision polymerized fluorene-bithiophene alternating copolymer shown in FIG. Since it does not exist, a high charge utilization rate is expected. In addition, the introduction of a monothiophene ring and a 2,2′-bithiophene ring (hereinafter referred to as “bithiophene ring”) changes the band structure and is expected to improve electrochemical activity. As a result of the study, it was found that the capacity was significantly increased by changing the conventional bulk polymerized polyfluorene to a precision polymerized fluorene-monothiophene alternating copolymer or a precision polymerized fluorene-bithiophene alternating copolymer.

  In the range of the precision polymerized fluorene-monothiophene alternating copolymer in the present invention, the fluorene ring is substantially bonded to the thiophene ring at the 2-position and the 7-position, and the bonding position of the thiophene ring to the fluorene ring is substantially As long as it is in the 2nd and 5th positions, in addition to a polymer constituted by an unsubstituted fluorene ring and an unsubstituted thiophene ring, a fluorene ring and / or a fluorene having a substituent at a position not involved in the bond with the thiophene ring A polymer containing at least one thiophene ring having a substituent at a position not participating in the bond with the ring is also included.

  Similarly, in the range of the precision polymerized fluorene-bithiophene alternating copolymer in the present invention, the fluorene ring is substantially bonded to the bithiophene ring at the 2nd and 7th positions, and the bonding position of the bithiophene ring to the fluorene ring is substantially the same. As long as it is in the 5th and 5 'positions, in addition to a polymer composed of an unsubstituted fluorene ring and an unsubstituted bithiophene ring, a fluorene ring having a substituent at a position not involved in the bond with the bithiophene ring, and Also included is a polymer containing at least one bithiophene ring having a substituent at a position not participating in the bond with the fluorene ring.

  The fluorene ring in the precision polymerized fluorene-monothiophene alternating copolymer and the precision polymerized fluorene-bithiophene alternating copolymer preferably has one or two substituents at the 9-position. The substituent at the 9-position does not decrease the electronic conductivity of the polymer, and the substituent increases the speed of the anion and cation doping and dedoping reactions and improves the output characteristics. The substituent at the 9-position consists of an alkyl group, a carboxyl group, a nitro group, a cyano group, an alkyl cyano group, a phenyl group, a halogen atom, a halogenated methyl group, a halogenated phenyl group, an alkylphenyl group, and an alkylhalogenated phenyl group. Preferably selected from the group.

  The thiophene ring in the precision polymerized fluorene-monothiophene alternating copolymer and the bithiophene ring in the precision polymerized fluorene-bithiophene alternating copolymer also have at least one substituent at a position that does not participate in the bond with the fluorene ring. Is preferred. Also in this case, the substituents increase the speed of the anion and cation doping and dedoping reactions, thereby improving the output characteristics. The substituent is preferably selected from the group consisting of alkyl groups, nitro groups, amino groups, cyano groups, carboxyl groups, formyl groups, alkoxy groups, alkoxycarbonyl groups and halogen atoms. As described above, these substituents increase the speed of the doping reaction and dedoping reaction and are electrochemically stable, so that the electrochemical stability of the electrode active material of the present invention is improved.

  The present invention also provides an electrode having an active material layer containing an electrode active material composed of the above-mentioned precision polymerized fluorene-monothiophene alternating copolymer and / or precision polymerized fluorene-bithiophene alternating copolymer. Precision polymerized fluorene-monothiophene alternating copolymers and precision polymerized fluorene-bithiophene alternating copolymers have a significantly increased capacity compared to bulk polymerized polyfluorene. Therefore, the electrode of the present invention can be suitably used for constructing an electrochemical device having a high capacity and a high energy density, or as one of a pair of electrodes in a secondary battery or an electric double layer capacitor It can be suitably used as one of a pair of electrodes in or as at least one of a pair of electrodes in an electrochemical capacitor.

  In the electrode of the present invention, the active material layer preferably contains at least one kind of carbon nanotube. Since carbon nanotubes have a high electrical conductivity, a composite with a high electrical conductivity can be obtained by compounding with an active material. In addition, since the outer surface area is large, the contact surface with the active material is widened, and conductivity can be imparted with high efficiency. Furthermore, the carbon nanotubes themselves have a capacity in contact with the electrolyte solution. Therefore, by using the precision polymerized fluorene-monothiophene alternating copolymer and / or the precision polymerized fluorene-bithiophene alternating copolymer and the carbon nanotube, an electrode having a high capacity and a low impedance characteristic can be obtained.

  The precisely polymerized fluorene-monothiophene alternating copolymer and / or the precisely polymerized fluorene-bithiophene alternating copolymer is preferably supported on carbon nanotubes. Since the contact resistance between the carbon nanotubes and the alternating copolymer is reduced, an electrode having further excellent low impedance characteristics can be obtained.

The specific surface area of the carbon nanotube is preferably in the range of 600 to 2600 m ² / g. Hereinafter, carbon nanotubes having a specific surface area in the range of 600 to 2600 m ² / g are referred to as “HSCNT”. The specific surface area of the carbon nanotube can be obtained by a nitrogen adsorption method.

Carbon nanotubes exhibit high electrical conductivity, and the capacity in contact with the electrolyte solution increases as the specific surface area increases. A carbon nanotube having a bundle structure in which several hundred tubes are bundled by van der Waals force has a specific surface area of at most 500 m ² / g (hereinafter, carbon nanotubes having a specific surface area of less than 600 m ² / g are referred to as “LSCNT”). However, there is known a method for obtaining HSCNT having no bundle or a large specific surface area. Moreover, since this HSCNT has a large specific surface area and high structural integrity, it is also known that the withstand voltage is high (see Patent Document 5).

  When such a high specific surface area HSCNT is combined with a precision polymerized fluorene-monothiophene alternating copolymer and / or a precision polymerized fluorene-bithiophene alternating copolymer, a composite with high electrical conductivity can be obtained. . Moreover, since the outer surface area of HSCNT is remarkably large, the contact area between the alternating copolymer and HSCNT can be greatly increased, and the conductivity can be imparted extremely efficiently. Furthermore, HSCNT itself has a high capacity in contact with the electrolyte solution. Therefore, an electrode of the present invention having an active material layer containing a composite of HSCNT and a precision polymerized fluorene-monothiophene alternating copolymer and / or a precision polymerized fluorene-bithiophene alternating copolymer is obtained by using bulk polymerized polyfluorene and LSCNT. Compared with an electrode having an active material layer containing a composite with the above, it has a greatly increased capacity and low impedance characteristics.

HSCNT preferably contains semiconducting carbon nanotubes. When the semiconducting carbon nanotubes are polarized in contact with the electrolyte solution, p-doping and n-doping occur to increase the carrier density and improve the electric capacity. Can do. Moreover, it is preferable that the density of HSCNT is 0.2-1.5 g / cm < ³ > high density. If the density is less than 0.2 g / cm ³ , it tends to be mechanically brittle, and if it is greater than 1.5 g / cm ³ , the specific surface area decreases.

  Precise polymerization fluorene-monothiophene alternating in which the fluorene ring is bonded to the thiophene ring at the 2nd and 7th positions and the thiophene ring is bonded to the fluorene ring at the 2nd and 5th positions in the present invention. The electrode active material made of a copolymer and the fluorene ring are substantially bonded to the bithiophene ring at the 2nd and 7th positions, and the bithiophene ring is bonded to the fluorene ring substantially at the 5th and 5 'positions. The electrode active material composed of the precision polymerized fluorene-bithiophene alternating copolymer has a significantly increased capacity compared to the electrode active material composed of the conventional bulk polymerized polyfluorene.

  Therefore, an electrode having an active material layer containing the electrode active material of the present invention is extremely useful for constructing electrochemical devices such as secondary batteries, electric double layer capacitors, and electrochemical capacitors having high capacity and high energy density. Useful.

  In the electrode active material of the present invention, first, the fluorene ring is bonded to the thiophene ring substantially at the 2nd and 7th positions, and the thiophene ring is bonded to the fluorene ring substantially at the 2nd and 5th positions. It consists of a polymerized fluorene-monothiophene alternating copolymer. Electrode active materials made of precision polymerized fluorene-monothiophene alternating copolymers have a significantly increased capacity compared to electrode active materials made of conventional bulk polymerized polyfluorene. The precise polymerized fluorene-monothiophene alternating copolymer as the electrode active material may be a single material or a mixture of different precision polymerized fluorene-monothiophene alternating copolymers.

  In the precision polymerized fluorene-monothiophene alternating copolymer in the present invention, the fluorene ring is bonded to the thiophene ring substantially at the 2-position and 7-position, and the bonding position of the thiophene ring to the fluorene ring is substantially 2-position. As long as it is in the 5-position, it may be constituted by an unsubstituted fluorene ring and an unsubstituted thiophene ring, and at least one fluorene ring constituting the precision polymerized fluorene-monothiophene alternating copolymer is a thiophene ring. At least one substituent may be present at a position not involved in the bonding of and / or at least one thiophene ring constituting the precisely polymerized fluorene-monothiophene alternating copolymer is bonded to the fluorene ring. It may have at least one substituent at a position not involved in. When two or more substituents are present in one fluorene ring or one thiophene ring, these substituents may be the same or different. Further, the substituents of different fluorene rings in the precision polymerized fluorene-monothiophene alternating copolymer may be the same or different, and the substituents of different thiophene rings may be the same or different.

  The fluorene ring preferably has 1 or 2 substituents at the 9-position. The substituent at the 9-position does not decrease the electronic conductivity of the polymer, and the substituent increases the speed of the anion and cation doping and dedoping reactions and improves the output characteristics.

  The substituent at the 9-position of the fluorene ring includes hydroxyl group; nitro group; amino group; alkylamino group such as methylamino, ethylamino, dimethylamino; cyano group; alkylcyano group such as methylcyano, ethylcyano, propylcyano; Halogen atom such as iodine, bromine, chlorine, fluorine; chain or branched alkyl group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl It is done. The alkyl group may be substituted by a hydroxyl group, a nitro group, an amino group, a cyano group, a halogen atom, an alkoxy group or an aryl group. Examples include chloromethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl. , Trifluoromethyl, difluoroethyl, methoxyethyl, ethoxyethyl, benzyl, phenethyl, cumyl, hydrocinnamyl.

  Substituents at the 9-position of the fluorene ring further include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl; linear or branched -Like alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy.

  As the substituent at the 9-position of the fluorene ring, an alkenyl group such as ethenyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, cyclopentenyl group, cyclohexenyl group, cyclohexedienyl group; alkynyl group such as Ethynyl, propynyl, butynyl, pentynyl, hexynyl; aromatic groups such as phenyl, naphthyl, anthryl, phenalenyl, phenanthryl, pyrenyl; heterocyclic groups such as pyridyl, pyrazyl, pyrimidyl, pyrrolyl, indenyl, furyl, oxazolyl, thiazolyl, Thienyl is mentioned. These groups may be substituted by hydroxyl group, nitro group, amino group, cyano group, halogen atom, alkyl group, alkoxy group. Examples include styryl, tolyl, xylyl, mesityl, fluorophenyl, fluoromethylphenyl. , Methoxyphenyl, ethoxyphenyl, methylpyridyl, methylpyrazyl.

  As the substituent at the 9-position of the fluorene ring, a carboxyl group; an alkylcarbonyl group such as acetyl, ethylcarbonyl, propylcarbonyl, butylcarbonyl, pentylcarbonyl, hexylcarbonyl; an alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl, Propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, hexyloxycarbonyl; alkylcarbonyloxy groups such as acetoxy, ethylcarbonyloxy, propylcarbonyloxy, butylcarbonyloxy, pentylcarbonyloxy, hexylcarbonyloxy; ester groups such as methyl ester, Ethyl ester, phenyl ester; carbamoyl group such as methylcarbamoyl, ethylcarbamoyl, E carbamoylmethyl and the like.

  Examples of the substituent at the 9-position of the fluorene ring include an alkyl group, a carboxyl group, a nitro group, a cyano group, an alkylcyano group, a phenyl group, a halogen atom, a halogenated methyl group, a halogenated phenyl group, an alkylphenyl group, and an alkylhalogen. Preferred is a phenyl group. Particularly, it is preferable that the substituent at the 9-position is a substituent having an alkyl group or a phenyl group, since the doping reaction and dedoping reaction of the anion and cation to be doped are further accelerated and the output characteristics are improved. Examples of the former include 9,9-dimethylfluorene and 9,9-dioctylfluorene, and examples of the latter include 9-methyl-9-phenylfluorene, 9-methyl-9-benzylfluorene, benzalfluorene, and benzhydrylidinefluorene. be able to. Among these, when doping or dedoping a large molecular cation, an alkyl group having 1 to 8 carbon atoms is preferable.

  The fluorene ring can also have a substituent at a position that does not participate in bonding with the thiophene ring other than the 9-position. Substituents at these positions can also be selected from the range of groups shown above for the 9-position substituent.

  The thiophene ring also preferably has a substituent at a position not participating in the bond with the fluorene ring. These substituents increase the speed of anion and cation doping and dedoping reactions and improve output characteristics.

  The substituent of the thiophene ring includes a hydroxyl group; a nitro group; an amino group; an alkylamino group such as methylamino, ethylamino, dimethylamino; a cyano group; an alkylcyano group such as methylcyano, ethylcyano, propylcyano; a halogen atom, Examples include iodine, bromine, chlorine, fluorine; chain or branched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl. The alkyl group may be substituted by a hydroxyl group, a nitro group, an amino group, a cyano group, a halogen atom, an alkoxy group or an aryl group. Examples include chloromethyl, dichloromethyl, trichloromethyl, fluoromethyl, difluoromethyl. , Trifluoromethyl, difluoroethyl, methoxyethyl, ethoxyethyl, benzyl, phenethyl, cumyl, hydrocinnamyl.

  Substituents on the thiophene ring further include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl; linear or branched alkoxy Groups such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy are mentioned.

  The substituent of the thiophene ring may further include an alkenyl group such as ethenyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, cyclopentenyl group, cyclohexenyl group, cyclohexedienyl group; alkynyl group such as ethynyl, propynyl , Butynyl, pentynyl, hexynyl; aromatic groups such as phenyl, naphthyl, anthryl, phenalenyl, phenanthryl, pyrenyl; aryloxy groups such as phenoxy; heterocyclic groups such as pyridyl, pyrazyl, pyrimidyl, pyrrolyl, indenyl, furyl, Examples include oxazolyl and thiazolyl. These groups may be substituted by hydroxyl group, nitro group, amino group, cyano group, halogen atom, alkyl group, alkoxy group. Examples include styryl, tolyl, xylyl, mesityl, fluorophenyl, fluoromethylphenyl. , Methoxyphenyl, ethoxyphenyl, methylpyridyl, methylpyrazyl.

  The substituent of the thiophene ring further includes formyl group; carboxyl group; alkylcarbonyl group such as acetyl, ethylcarbonyl, propylcarbonyl, butylcarbonyl, pentylcarbonyl, hexylcarbonyl; alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl, Propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, hexyloxycarbonyl; alkylcarbonyloxy groups such as acetoxy, ethylcarbonyloxy, propylcarbonyloxy, butylcarbonyloxy, pentylcarbonyloxy, hexylcarbonyloxy.

  The substituent of the thiophene ring is preferably selected from the group consisting of an alkyl group, a nitro group, an amino group, a cyano group, a carboxyl group, a formyl group, an alkoxy group, an alkoxycarbonyl group, and a halogen atom. These substituents are electrochemically stable and increase the electrochemical stability of the electrode active material of the present invention in addition to increasing the rate of anion and cation doping and dedoping reactions.

  These substituents are preferably bonded to the 3-position and / or 4-position of the thiophene ring. When the substituent is bonded to the 3-position and 4-position of the thiophene ring, they are bonded to each other. A saturated or unsaturated ring may be formed together with the atoms present. Examples of the group to which the 3-position and 4-position substituents are bonded include a propylene group, a butylene group, an ethylenedioxy group, and a butadienylene group.

These precision polymerized fluorene-monothiophene alternating copolymers can be obtained by known methods. For example, a Suzuki coupling method using a palladium catalyst can be used. In the following formula I, an example of production by the Suzuki coupling method is shown.

  In the electrode active material of the present invention, the fluorene ring is substantially bonded to the bithiophene ring at the 2nd and 7th positions, and the bithiophene ring is substantially bonded to the fluorene ring at the 5th and 5 'positions. It consists of a precision polymerized fluorene-bithiophene alternating copolymer. The electrode active material made of precision polymerized fluorene-bithiophene alternating copolymer has a significantly increased capacity compared to the electrode active material made of conventional bulk polymerized polyfluorene. The precision polymerized fluorene-bithiophene alternating copolymer as the electrode active material may be a single material or a mixture of different precision polymerized fluorene-bithiophene alternating copolymers.

  In the precision polymerized fluorene-bithiophene alternating copolymer in the present invention, the fluorene ring is bonded to the bithiophene ring substantially at the 2nd and 7th positions, and the bonding positions of the bithiophene ring to the fluorene ring are substantially at the 5th and 5th positions. As long as it is in the ′ -position, it may be constituted by an unsubstituted fluorene ring and an unsubstituted bithiophene ring, and at least one fluorene ring constituting the precision polymerized fluorene-bithiophene alternating copolymer is a bithiophene ring. It may have at least one substituent at a position not participating in the bond, and / or at least one bithiophene ring constituting the precisely polymerized fluorene-bithiophene alternating copolymer is involved in the bond with the fluorene ring You may have at least 1 substituent in the position which does not. When two or more substituents are present in one fluorene ring or one bithiophene ring, these substituents may be the same or different. Further, the substituents of different fluorene rings in the precision polymerized fluorene-bithiophene alternating copolymer may be the same or different, and the substituents of different bithiophene rings may be the same or different.

  Also in the precision polymerized fluorene-bithiophene alternating copolymer, the fluorene ring preferably has one or two substituents at the 9-position. The substituent at the 9-position does not decrease the electronic conductivity of the polymer, and the substituent increases the speed of the anion and cation doping and dedoping reactions and improves the output characteristics.

  The substituent at the 9-position of the fluorene ring in the precisely polymerized fluorene-bithiophene alternating copolymer should be selected from the range of the groups indicated as the substituent at the 9-position of the fluorene ring in the precisely polymerized fluorene-monothiophene alternating copolymer. A preferred group as the 9-position substituent of the fluorene ring of the precisely polymerized fluorene-monothiophene alternating copolymer is also preferred as the 9-position substituent of the fluorene ring of the precisely polymerized fluorene-bithiophene alternating copolymer.

  The fluorene ring in the precision polymerized fluorene-bithiophene alternating copolymer may also have a substituent at a position that does not participate in the bond with the bithiophene ring other than the 9-position. Substituents at these positions can also be selected from the range of groups shown above for the 9-position substituent.

  The bithiophene ring in the precision polymerized fluorene-bithiophene alternating copolymer preferably also has a substituent at a position that does not participate in the bond with the fluorene ring. These substituents increase the speed of anion and cation doping and dedoping reactions and improve output characteristics.

  The substituent of the bithiophene ring in the precision polymerized fluorene-bithiophene alternating copolymer can be selected from the range of the groups indicated as the substituent of the thiophene ring in the precision polymerized fluorene-monothiophene alternating copolymer. -A preferable group as a substituent of the thiophene ring of the monothiophene alternating copolymer is also preferable as a substituent of the bithiophene ring of the precision polymerized fluorene-bithiophene alternating copolymer.

  These substituents are preferably bonded to at least one position of the 3-position, 4-position, 3′-position, and 4′-position of the bithiophene ring, and the substituent is 3-position and 4-position and / or 3 of the thiophene ring. In the case where they are bonded to the '-position and the 4'-position, they may form a saturated or unsaturated ring together with the atoms to which they are bonded. Examples of the group in which the substituents at the 3-position and the 4-position and / or the 3′-position and the 4′-position are bonded include a propylene group, a butylene group, an ethylenedioxy group, and a butadienylene group.

These precision polymerized fluorene-bithiophene alternating copolymers can be obtained by known methods. For example, a Suzuki coupling method using a palladium catalyst can be used. In the following formula II, an example of production by the Suzuki coupling method is shown.

  The precision polymerized fluorene-monothiophene alternating copolymer and the precision polymerized fluorene-bithiophene alternating copolymer, which are the electrode active materials of the present invention, can be subjected to doping treatment to impart conductivity. As the doping process, either a chemical doping process or an electrochemical doping process may be employed.

Acceptors for chemical doping treatment include halogens such as Br ₂ , I ₂ and Cl ₂ , Lewis acids such as SO ₃ , BF ₃ , PF ₅ , AsF ₅ and SbF ₅ , HNO ₃ and H ₂ SO _4. Protonic acids such as HClO ₄ , CF ₃ SO ₃ H, FSO ₃ H, transition metal halides such as FeCl ₃ , MoCl ₅ , WCl ₅ , SnCl ₄ , MoF ₅ , tetracyanoethylene, tetracyanoquinodimethane, chloranil, etc. Organic materials such as Li, Na, K, and Cs can be used as donors.

As an acceptor for electrochemical doping treatment, Lewis acids such as BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ and SbF ₆ ⁻ , and halogen anions such as I ⁻ , Br ⁻ and Cl ⁻ can be used. As the donor, alkali metal ions such as Li ⁺ , Na ⁺ , K ⁺ , and Cs ⁺ , alkylammonium ions such as tetraethylammonium ions and tetrabutylammonium ions, and the like can be used.

  The doping amount is not particularly limited, but is preferably 5 to 100 mol% per fluorene monomer unit, more preferably 20 to 50 mol% per fluorene monomer unit. Polymerization may be performed after doping in a stage before polymerization, a method of doping after polymerization may be used, or doping may be performed by charging after electrode formation.

  The positive electrode active material subjected to these doping treatments undergoes a discharge reaction and a reduction reaction due to anodization of the anion. Further, the negative electrode active material subjected to these doping treatments causes a discharge reaction and an oxidation reaction due to cation dedoping.

  In addition, self-doped positive electrode active materials such as alkylsulfonate anion and alkylphosphonate anion can be reacted with fluorene, monothiophene, bithiophene, and anion that can be covalently bonded to fluorene, monothiophene, and bithiophene. A cation that can be covalently bonded to fluorene, monothiophene, bithiophene, such as a tertiary ammonium cation, is reacted with fluorene, monothiophene, bithiophene, polymerized, and self-doped negative electrode active material can do.

  The self-doped positive electrode active material causes a discharge reaction and a reduction reaction by doping of cations in the electrolytic solution. In addition, the self-doped negative electrode active material undergoes a discharge reaction and an oxidation reaction by doping anions in the electrolytic solution. When a self-doped positive electrode active material or negative electrode active material is used, the same type and amount of cations or anions are involved in the charge transfer reaction, so that the ion concentration in the electrolyte is kept constant, and therefore the conductivity of the electrolyte is constant. Is kept constant.

  An active material layer containing an electrode active material comprising the precision polymerized fluorene-monothiophene alternating copolymer and / or the precision polymerized fluorene-bithiophene alternating copolymer of the present invention is provided on a current collector, and used for an electrochemical device. An electrode can be formed. The active material layer may contain only the precision polymerized fluorene-monothiophene alternating copolymer, may contain only the precision polymerized fluorene-bithiophene alternating copolymer, or may contain both. good.

  As the current collector, a conductive material such as platinum, gold, nickel, aluminum, titanium, steel, or carbon can be used. As the shape of the current collector, any shape such as a film shape, a foil shape, a plate shape, a net shape, an expanded metal shape, and a cylindrical shape can be adopted.

  The active material layer is obtained by dissolving the above-mentioned precision polymerized fluorene-monothiophene alternating copolymer and / or precision polymerized fluorene-bithiophene alternating copolymer in a solvent such as chloroform, tetrahydrofuran, N-methylpyrrolidone, isopropyl alcohol and the like. The solution may be applied on a current collector and dried. The film-shaped active material layer thus formed has a high capacity, is thin and uniform, and reduces the resistance of the electrode. Therefore, the IR drop during discharge can be reduced and the voltage of the electrode can be kept high. it can. In addition, a current collector is inserted into a comonomer solution for forming a precision polymerized fluorene-monothiophene alternating copolymer and / or a precision polymerized fluorene-bithiophene alternating copolymer, and polymerized on the current collector. A material layer may be formed.

  Further, the active material layer may be formed using a mixed material obtained by mixing a binder and a conductive material with the above-described precision polymerized fluorene-monothiophene alternating copolymer and / or precision polymerized fluorene-bithiophene alternating copolymer.

  As the binder, known binders such as polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinyl fluoride, and carboxymethyl cellulose can be used. The content of the binder is preferably 1 to 20% by mass with respect to the total amount of the active material layer. When it is 1% by mass or less, the strength of the active material layer is not sufficient, and when it is 20% by mass or more, electrochemical characteristics such as capacity are insufficient.

  The conductive material may include known conductive materials such as carbon materials such as carbon black, natural graphite and artificial graphite, metal powders such as nickel and iron, and conductive oxides such as ITO. The content of these conductive materials is preferably 1 to 20% by mass with respect to the total amount of the active material layer. When the content is 1% by mass or less, the conductivity of the active material layer is insufficient, and when the content is 20% by mass or more, electrochemical characteristics such as capacity are insufficient.

  Other active materials may be further mixed in the active material layer as necessary. For example, other electrode active materials, for example, electron conductive polymers such as polythiophene, polypyrrole, and polyacene can be included. The amount of the other additive material is preferably 20% by mass or less based on the total amount of the active material layer. When it is 20% by mass or more, electrochemical characteristics such as capacity become insufficient.

  The electrode using the above-mentioned mixed material is obtained by dispersing the electrode active material of the present invention, a conductive material, and optionally other additive substances in a varnish in which a binder is dissolved, and collecting the obtained dispersion by a doctor blade method or the like. It can also be created by coating on top and drying. Alternatively, the obtained mixed material may be sandwiched between a net-like current collector to form an electrode.

  In a preferred embodiment, the active material layer includes a precision polymerized fluorene-monothiophene alternating copolymer and / or a precision polymerized fluorene-bithiophene alternating copolymer and a carbon nanotube. Since carbon nanotubes have a high electrical conductivity, a composite with a high electrical conductivity can be obtained by compounding with an active material. In addition, since the outer surface area is large, the contact surface with the active material is widened, and conductivity can be imparted with high efficiency. Furthermore, the carbon nanotubes themselves have a capacity in contact with the electrolyte solution. Therefore, by using the precision polymerized fluorene-monothiophene alternating copolymer and / or the precision polymerized fluorene-bithiophene alternating copolymer and the carbon nanotube, an electrode having a high capacity and a low impedance characteristic can be obtained.

As the carbon nanotube, LSCNT obtained by an arc discharge method, a laser evaporation method, a chemical vapor deposition (CVD) method, or the like and having a specific surface area of less than 600 m ² / g, which is a single layer, a multilayer, or a mixture thereof, is used. However, it is preferable to use HSCNT having a specific surface area in the range of 600 to 2600 m ² / g.

HSCNT can be used in both a single layer and a multi-layer, and both the one having an open end and the one having no opening can be used, and these may be mixed and used. . A single layer of HSCNT can be obtained by adding a small amount of water vapor to a reaction atmosphere in a chemical vapor deposition (CVD) method in the presence of a metal catalyst (“SCIENCE, Vol. 306, pp1362-1364 (2004). )"reference). In addition, for the production of HSCNT, a method described in Chemical Physics Letters 403, pp 320-323 (2005), etc., and a commercially available HiPco (manufactured by Carbon Nanotechnologies) with a specific surface area of about several hundred m ² / g are used. On the other hand, for example, a method of providing a means for releasing a bundle structure as described in Journal of Physical Chemistry B 2004, 108, pp 18396-18397 can be used.

The specific surface area of the HSCNT is preferably as large as possible, but is generally 600 m ² / g or more, preferably 700 m ² / g or more, more preferably 1000 m ² / g or more, and particularly preferably 1500 m ² / g or more. The upper limit is generally 2600 m ² / g. In the case of HSCNT the tip is not opening, the specific surface area of generally 600~1300m ² / g, more preferably 800~1300m ² / g, more preferably from 1000~1300m ² / g. In the case of HSCNT having an open end, the specific surface area is generally 1300 to 2600 m ² / g, more preferably 1500 to 2600 m ² / g, and even more preferably 1700 to 2600 m ² / g.

  HSCNT preferably contains semiconducting carbon nanotubes. When the semiconducting carbon nanotubes are polarized in contact with the electrolyte solution, p-doping and n-doping occur to increase the carrier density and improve the electric capacity. Can do.

Moreover, it is preferable to use HSCNT having a high density. When the density is high, the capacity per unit volume can be greatly increased. The density range is generally 0.2 to 1.5 g / cm ³ , preferably 0.3 to 1.2 g / cm ³ , particularly preferably 0.4 to 1.0 g / cm ³ . If the density is less than 0.2 g / cm ³ , it tends to be mechanically brittle, and if it is greater than 1.5 g / cm ³ , the specific surface area decreases. Densification can be performed by, for example, exposing HSCNT obtained by the above-described CVD method or the like to a liquid and then drying it. The liquid used at this time is compatible with HSCNT and can be in a wet state, and it is desirable that the liquid does not remain in HSCNT after drying. Water, alcohols (for example, isopropyl alcohol, ethanol, methanol) Acetone (for example, acetone), hexane, toluene, cyclohexane, dimethylformamide, and the like can be preferably used (see Japanese Patent Application Laid-Open No. 2007-182352).

  A fine polymerized fluorene-monothiophene alternating copolymer and / or a precision polymerized fluorene-bithiophene alternating copolymer and a carbon nanotube are mixed to obtain a composite of both, and an active material layer containing this composite is formed. be able to. At this time, if necessary, the active material layer may be formed by mixing both using a dispersion medium and then drying.

  However, a precisely polymerized fluorene-monothiophene alternating copolymer and / or a precisely polymerized fluorene-bithiophene alternating copolymer is supported on a carbon nanotube to obtain a composite of both, and an active material layer is formed using this composite Is particularly preferred. For loading, carbon nanotubes are immersed in a solution obtained by dissolving the above alternating copolymer in a solvent such as chloroform, tetrahydrofuran, N-methylpyrrolidone, isopropyl alcohol, and after a predetermined time has passed, the carbon nanotubes are collected and dried. Can be performed. After the drying, the alternating copolymer film is formed on the surface of the carbon nanotube. This film has a high capacity, is thin and uniform and has low resistance, and has good adhesion between the carbon nanotube and the alternating copolymer film and low contact resistance, so that the IR drop during discharge is further reduced. And the electrode voltage can be kept higher.

  The mass ratio of the precisely polymerized fluorene-monothiophene alternating copolymer and / or the precisely polymerized fluorene-bithiophene alternating copolymer and the carbon nanotube in the active material layer is generally in the range of 9: 1 to 1: 9, preferably Is in the range of 8: 2 to 2: 8. Exceeding this range results in insufficient electrochemical properties.

  After forming an active material layer containing a precision polymerized fluorene-monothiophene alternating copolymer and / or a precision polymerized fluorene-bithiophene alternating copolymer and a carbon nanotube into a predetermined shape such as a sheet shape, A composite electrode for an electrochemical element can be obtained by joining the electric body. For example, a composite electrode can be obtained by pressure-bonding the obtained molded body on a current collector.

  The electrode of the present invention can be suitably used in an electrochemical device having a pair of electrodes, a separator disposed between the electrodes, and an electrolyte solution.

  As a separator used for an electrochemical element, a polyolefin fiber nonwoven fabric, a glass fiber nonwoven fabric, etc. are used suitably, for example. There are a nonaqueous electrolytic solution and an aqueous electrolytic solution as the electrolytic solution, and they are appropriately selected according to the application.

  As the solvent for the non-aqueous electrolyte, electrochemically stable ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, sulfolane, 3-methyl sulfolane, γ-butyrolactone, acetonitrile, and dimethoxyethane, N-methyl-2-pyrrolidone, dimethylformamide or a mixture thereof can be preferably used.

As a solute of the nonaqueous electrolytic solution, a salt that generates lithium ions when dissolved in an organic electrolytic solution can be used without any particular limitation. For _{example, LiPF 6, LiBF 4, LiClO} 4, LiN (CF 3 SO 2) 2, LiCF 3 SO 3, LiC (SO 2 CF 3) 3, LiN (SO 2 C 2 F 5) 2, LiAsF 6, LiSbF 6 Or a mixture thereof can be preferably used. Further, a quaternary ammonium salt or a quaternary phosphonium salt having a quaternary ammonium cation or a quaternary phosphonium cation can be used as a solute of the nonaqueous electrolytic solution. For example, a cation represented by R ¹ R ² R ³ R ⁴ N ⁺ or R ¹ R ² R ³ R ⁴ P ⁺ (where R ¹ , R ² , R ³ and R ⁴ are alkyl having 1 to 6 carbon atoms) Group), PF ₆ ⁻ , BF ₄ ⁻ , ClO ₄ ⁻ , N (CF ₃ SO ₃ ) ₂ ⁻ , CF ₃ SO ₃ ⁻ , C (SO ₂ CF ₃ ) ₃ ⁻ , N (SO ₂ C ₂ A salt composed of an anion composed of F ₅ ) ₂ ⁻ , AsF ₆ ^— or SbF ₆ ^— , or a mixture thereof can be suitably used. In particular, a salt using PF ₆ ⁻ , BF ₄ ⁻ , ClO ₄ ⁻ or N (CF ₃ SO ₃ ) ₂ ⁻ as the anion is preferable as the solute.

  Examples of the solute cations in the acidic, neutral or alkaline aqueous electrolyte include cations of alkali metals such as sodium and potassium, and protons. Solute anions in aqueous electrolytes include anions of inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, tetrafluoroboric acid, hexafluorophosphoric acid, hexafluorosilicic acid, saturated monocarboxylic acids, aliphatic carboxylic acids And anions of organic acids such as oxycarboxylic acid, p-toluenesulfonic acid, polyvinylsulfonic acid and lauric acid.

  The electrode of the present invention can be suitably used as at least one of a pair of electrodes in an electrochemical device. Precision polymerized fluorene-monothiophene alternating copolymers and precision polymerized fluorene-bithiophene alternating copolymers have a significantly increased capacity compared to bulk polymerized polyfluorene. Therefore, by using the composite electrode of the present invention as an electrode for any electrochemical device, an electrochemical device having a high capacity and a high energy density can be obtained. Hereinafter, each case where the electrochemical element is a secondary battery, an electric double layer capacitor, or an electrochemical capacitor will be described.

(Secondary battery)
In the case of a lithium secondary battery, a non-aqueous electrolyte solution having a lithium salt as a solute is used as the electrolyte solution. Then, the electrode of the present invention is used as the positive electrode, and an electrode using an electrode active material that occludes and releases lithium ions such as conventional lithium metal or natural graphite, artificial graphite, and petroleum coke is used as the negative electrode. In the positive electrode of the present invention using the self-doped precision polymerized fluorene-monothiophene alternating copolymer and / or precision polymerized fluorene-bithiophene alternating copolymer as the electrode active material, the same amount is involved in the charge / discharge reaction. Since it is a lithium cation, the ion concentration of the electrolytic solution can be kept constant, and the conductivity of the electrolytic solution can be kept constant.

  In the lithium secondary battery having this configuration, the positive electrode of the present invention exhibits higher charge utilization than the positive electrode using bulk-polymerized polyfluorene as an electrode active material, and the electrolysis voltage of the non-aqueous electrolyte is high. Therefore, the operating voltage is high, the capacity is high, and the energy density is high.

  Further, when the electrode active material of the present invention is used for the negative electrode and a conventional layered compound such as lithium cobaltate or a conductive polymer such as polyaniline or polyphenylene is used as the electrode active material for the positive electrode, lithium ion intercalation is caused. Therefore, a lithium secondary battery with improved output characteristics and cycle characteristics, high operating voltage, high capacity and high energy density can be obtained.

  In the case of forming a proton battery, an acid aqueous solution having protons is used as an electrolytic solution. And the electrode of this invention is used as a positive electrode, and the negative electrode in well-known proton batteries, such as a quinoxaline type polymer, is used as a negative electrode. The proton battery having this configuration uses an electrolytic solution made of an acid aqueous solution, has good charge / discharge characteristics, has a high energy density, and the positive electrode of the present invention has a higher charge than the positive electrode using bulk polymerized polyfluorene as an electrode active material. The utilization factor is shown, and 1.2 V which is the maximum operating voltage in a battery using an aqueous electrolyte is shown.

(Electric double layer capacitor)
As the electrolytic solution for the electric double layer capacitor, any of the above-mentioned non-aqueous electrolytic solution and aqueous electrolytic solution can be used. In an electric double layer capacitor using a non-aqueous electrolyte, the electrode of the present invention is used as a positive electrode or a negative electrode, and the other electrode is an electric material such as activated carbon, carbon fiber, phenol resin carbide, vinylidene chloride resin carbide, microcrystalline carbon, etc. An electrode having a double layer capacity is used. Since the positive electrode of the present invention has a capacity characteristic significantly increased from the positive electrode using bulk polymerized polyfluorene as an electrode active material, and since the electrolysis voltage of the non-aqueous electrolyte is high, the operating voltage can be increased, An electric double layer capacitor having a high operating voltage, high capacity and high energy density can be obtained.

  In addition, in an electric double layer capacitor using an aqueous electrolyte, the electrode of the present invention is used as a positive electrode, and the other electrode is made of an electric two-layer such as activated carbon, carbon fiber, phenol resin carbide, vinylidene chloride resin carbide, and microcrystalline carbon. An electrode having a multilayer capacity is used. The electric double layer capacitor having this configuration can use acidic, neutral, and alkaline electrolytes, has good charge / discharge characteristics, high energy density, and the positive electrode of the present invention uses bulk-polymerized polyfluorene as an electrode active material. The charge utilization rate is higher than that of the positive electrode, and the maximum operating voltage of the electric double layer capacitor using the aqueous electrolyte is 1.2 V.

(Electrochemical capacitor)
As an electrolytic solution for the electrochemical capacitor, a nonaqueous electrolytic solution having a quaternary ammonium salt or a quaternary phosphonium salt as a solute is used. Then, the electrode of the present invention can be used as the positive electrode, and an electrode using a conventional conductive polymer such as polyacetylene, polyacene, or polyphenylene having redox reaction characteristics as the negative electrode can be used as the electrode active material. In the electrochemical capacitor having this configuration, the positive electrode of the present invention has a capacity that is significantly increased as compared with the positive electrode using bulk-polymerized polyfluorene as an electrode active material, and has a high operating voltage, high capacity, and high energy density.

  In addition, a conventional conductive polymer such as polyaniline, polyacetylene and polyphenylene having redox reaction characteristics or an electrode using a metal oxide such as ruthenium oxide, manganese oxide and nickel oxide as an electrode active material is used as a positive electrode, and this electrode is used as a negative electrode. The electrode of the invention can also be used. In the electrochemical capacitor having this configuration, the negative electrode of the present invention has a higher capacity than the negative electrode using bulk polymerized polyfluorene or metal oxide as an electrode active material, has a higher operating voltage, a higher capacity, and a higher energy density.

  Furthermore, when the electrode of the present invention is used for both of the pair of electrodes in the electrochemical capacitor, an electrochemical capacitor having a high operating voltage, a high capacity, and a high energy density can be obtained. In addition, when the self-doping type precision polymerized fluorene-monothiophene alternating copolymer and / or the precision polymerized fluorene-bithiophene alternating copolymer are used, the same kind and the same amount of ions are involved in the reaction. The ion concentration inside is kept constant, and the conductivity of the electrolyte is kept constant.

  Examples of the present invention are shown below, but the present invention is not limited to the following examples.

Example 1: Precision Polymerized Fluorene-Monothiophene Alternating Copolymer / LSCNT Composite Electrode 5 mL of toluene, 5 mL of ethanol, 1 mmol of 2,7-dibromofluorene, 1 mmol of 2,5-thiophene diboronic acid bis (2 , 2-dimethyl-1,3-propanediol) ester, 0.01 mmol of Pd (PPh ₃ ) ₄ , 4 mL of 2M Na ₂ CO ₃ solution were added and stirred at 80 ° C. for 20 hours to obtain the product. The product was filtered and washed to obtain a yellow powder precision polymerized fluorene-monothiophene alternating copolymer represented by the following formula III.

Subsequently, 20 mg of precision polymerized fluorene-monothiophene alternating copolymer powder and 10 mg of LSCNT powder (specific surface area: 200 m ² / g) were added to 50 mL of isopropyl alcohol, and a dispersion was obtained by mechanical stirring. The dispersion was filtered to obtain a precision polymerized fluorene-monothiophene alternating copolymer / LSCNT composite sheet in which the precision polymerized fluorene-monothiophene alternating copolymer was supported on LSCNT. The sheet was cut to about 2 cm ² and crimped to an aluminum current collector of the same size to obtain a precision polymerized fluorene-monothiophene alternating copolymer / LSCNT composite electrode. Using the obtained precision polymerized fluorene-monothiophene alternating copolymer / LSCNT composite electrode as a working electrode, using an activated carbon sheet as a counter electrode and a silver-silver ion electrode as a reference electrode, a cyclic voltammogram was obtained in a tripolar cell. It was measured. As the electrolytic solution, propylene carbonate in which 1M tetraethylammonium tetrafluoroborate was dissolved was used. The potential range was −2 V to +1 V, and the potential scanning speed was 5 mVs ⁻¹ .

Example 2: Precision Polymerized Fluorene-Bithiophene Alternating Copolymer / LSCNT Composite Electrode 5 mL of toluene, 5 mL of ethanol, 1 mmol of 2,7-dibromofluorene, 1 mmol of 2,2′-bithiophene-5,5′- Diboronic acid bis (pinacol) ester, 0.01 mmol of Pd (PPh ₃ ) ₄ and 4 mL of 2M Na ₂ CO ₃ solution were added and stirred at 80 ° C. for 20 hours to obtain the product. The product was filtered and washed to obtain a yellow polymer precision polymerized fluorene-bithiophene alternating copolymer represented by Formula IV.

  Subsequently, the obtained precision polymerized fluorene-bithiophene alternating copolymer was used in place of the precision polymerized fluorene-monothiophene alternating copolymer of Example 1, and the same procedure as in Example 1 was followed. A polymer / LSCNT composite electrode was obtained and a cyclic voltammogram was measured.

Example 3: Precision polymerized fluorene-monothiophene alternating copolymer / HSCNT composite electrode Example 1 except that 50 mg of HSCNT powder (specific surface area: 900 m ² / g) was used instead of 50 mg of LSCNT powder. The procedure was repeated to obtain a precision polymerized fluorene-monothiophene alternating copolymer / HSCNT composite electrode, and a cyclic voltammogram was measured.

Example 4: Precision polymerized fluorene-bithiophene alternating copolymer / HSCNT composite electrode The precision polymerized fluorene-bithiophene alternating copolymer obtained in Example 2 was used in place of the precision polymerized fluorene-monothiophene alternating copolymer. Except for the points, the procedure of Example 3 was repeated to obtain a precision polymerized fluorene-bithiophene alternating copolymer / HSCNT composite electrode, and a cyclic voltammogram was measured.

Comparative Example 1: Bulk Polymerized Polyfluorene / LSCNT Composite Electrode By adding 10 mmol of FeCl ₃ to acetonitrile in which 10 mmol of fluorene monomer is dissolved, stirring at room temperature for 72 hours, filtering and drying (60 ° C. vacuum drying for 24 hours) A bulk-polymerized polyfluorene powder of a tan powder represented by the following formula V was obtained.

  Subsequently, the obtained bulk polymerized polypropylene was used in place of the precision polymerized fluorene-monothiophene alternating copolymer of Example 1, and a bulk polymerized polyfluorene / LSCNT composite electrode was obtained in the same procedure as in Example 1. Click voltammograms were measured.

  In FIG. 2, the cyclic voltammogram of Example 1 is shown in comparison with the cyclic voltammogram of Comparative Example 1. In FIG. 3, the cyclic voltammogram of Example 2 is shown in comparison with the cyclic voltammogram of Comparative Example 1. In FIG. 4, the cyclic voltammogram of Example 3 is shown in comparison with the cyclic voltammogram of Comparative Example 1. FIG. 5 shows the cyclic voltammogram of Example 4 in comparison with the cyclic voltammogram of Comparative Example 1.

Table 1 shows values of the differential capacity and the integrated capacity obtained from the results of the cyclic voltammograms of Examples 1 to 4 and the cyclic voltammogram of Comparative Example 1.

  As is clear from Table 1, the composite electrode of the present invention using the LSCNT of Examples 1 and 2 was about 2.8 times as much as the bulk polymerized polyfluorene / LSCNT composite electrode of Comparative Example 1. The composite electrode of the present invention having an integral capacity and using the HSCNTs of Examples 3 and 4 is about 3.3 times as large as the bulk polymerized polyfluorene / LSCNT composite electrode of Comparative Example 1. Has integral capacity. Moreover, since the peak of a cyclic voltammogram is sharp, it turns out that electroconductivity improves and the low impedance characteristic is acquired in the composite electrode of this invention of Examples 1-4.

(A) is a figure which shows the fluorene-monothiophene chain in a precision polymerization fluorene-monothiophene alternating copolymer, (b) is a figure which shows the fluorene-bithiophene chain in a precision polymerization fluorene-bithiophene alternating copolymer. Yes, (c) is a diagram showing the fluorene chain in the bulk polymerized polyfluorene. It is a cyclic voltammogram of a precision polymerization fluorene-monothiophene alternating copolymer / LSCNT composite electrode. It is a cyclic voltammogram of a precision polymerization fluorene-bithiophene alternating copolymer / LSCNT composite electrode. It is a cyclic voltammogram of a precision polymerization fluorene-monothiophene alternating copolymer / HSCNT composite electrode. It is a cyclic voltammogram of a precision polymerization fluorene-bithiophene alternating copolymer / HSCNT composite electrode.

Claims (15)

An electrode active material comprising at least one alternating copolymer composed of fluorene and thiophene,
The fluorene ring of the alternating copolymer is substantially bonded to the thiophene ring at the 2nd and 7th positions, and the bonding position of the thiophene ring to the fluorene ring is substantially at the 2nd and 5th positions. Electrode active material. An electrode active material comprising at least one alternating copolymer composed of fluorene and 2,2′-bithiophene,
The fluorene ring of the alternating copolymer is bonded to the 2,2′-bithiophene ring at the 2nd and 7th positions, and the bonding position of the 2,2′-bithiophene ring to the fluorene ring is substantially at the 5th position. And an electrode active material characterized by being 5'-position.   The electrode active material according to claim 1 or 2, wherein the alternating copolymer includes at least one fluorene ring having a substituent at the 9-position.   The substituent is a group consisting of an alkyl group, a carboxyl group, a nitro group, a cyano group, an alkylcyano group, a phenyl group, a halogen atom, a halogenated methyl group, a halogenated phenyl group, an alkylphenyl group, and an alkylhalogenated phenyl group. The electrode active material according to claim 3, selected from:   5. The thiophene ring or the 2,2′-bithiophene ring in the alternating copolymer has at least one substituent at a position not participating in the bond with the fluorene ring. Electrode active material.   The electrode active material according to claim 5, wherein the substituent is selected from the group consisting of an alkyl group, a nitro group, an amino group, a cyano group, a carboxyl group, a formyl group, an alkoxy group, an alkoxycarbonyl group, and a halogen atom.   The electrode which has an active material layer containing the electrode active material of any one of Claims 1-6.   The electrode according to claim 7, wherein the active material layer contains at least one carbon nanotube.   The electrode according to claim 8, wherein the alternating copolymer is supported on the carbon nanotubes. The electrode according to claim 8 or 9, wherein the carbon nanotube has a specific surface area of 600 to 2600 m ² / g.   The electrode according to claim 10, wherein the carbon nanotube contains a semiconducting carbon nanotube. The electrode according to claim 10 or 11, wherein a density of the carbon nanotube is in a range of 0.2 to 1.5 g / cm ³ .   The electrode according to any one of claims 7 to 12, which is used as one of a pair of electrodes in a secondary battery.   The electrode according to any one of claims 7 to 12, which is used as one of a pair of electrodes in an electric double layer capacitor.   The electrode according to any one of claims 7 to 12, which is used as at least one of a pair of electrodes in an electrochemical capacitor.

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