JP2011113839A - Electrode active material and secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode active material and a secondary battery with excellent cycle characteristics, allowing a high output with a high energy density and hardly reducing its capacity even when a charge and a discharge are repeated. <P>SOLUTION: The electrode active material mainly comprises an organic compound having a diamine structure in its constitutional unit. Specifically, the organic compound comprises a conjugated diamine structure expressed by general formula (I) and phenazine structures expressed by general formulae (II), (III) in the constitutional unit. In the formulae, each of R<SB>1</SB>-R<SB>6</SB>presents a substituted or non-substituted alkyl group or the like, and each of X<SB>1</SB>-X<SB>12</SB>presents a hydrogen atom or an arbitrary substituent. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrode active material and a secondary battery, and more particularly to an electrode active material using an organic compound, and a secondary battery that repeats charging and discharging using a battery electrode reaction of the electrode active material.

  With the expansion of the market for portable electronic devices such as mobile phones, notebook computers, and digital cameras, secondary batteries with high energy density and long life are expected as cordless power sources for these electronic devices.

  In response to such demands, secondary batteries have been developed that use an alkali metal ion such as lithium ion as a charge carrier and use an electrochemical reaction associated with the charge exchange. In particular, lithium ion secondary batteries having a high energy density are now widely used.

  Among the constituent elements of the secondary battery, the electrode active material is a substance that directly contributes to a battery electrode reaction such as a charge reaction and a discharge reaction, and has a central role of the secondary battery. That is, the battery electrode reaction is a reaction that occurs with the transfer of electrons by applying a voltage to an electrode active material that is electrically connected to an electrode disposed in the electrolyte, and proceeds during charging and discharging of the battery. To do. Therefore, as described above, the electrode active material has a central role of the secondary battery in terms of system.

  In the lithium ion secondary battery, a lithium-containing transition metal oxide is used as a positive electrode active material, a carbon material is used as a negative electrode active material, and an insertion reaction and a desorption reaction of lithium ions with respect to these electrode active materials are used. Charging / discharging.

  However, the lithium ion secondary battery has a problem that the rate of charge and discharge is limited because the movement of lithium ions in the positive electrode is rate-limiting. That is, in the above-described lithium ion secondary battery, the migration rate of lithium ions in the transition metal oxide of the positive electrode is slower than that of the electrolyte and the negative electrode, and therefore the battery reaction rate at the positive electrode becomes the rate-determining rate. As a result, there is a limit to increasing the output and shortening the charging time.

  In order to solve such problems, research and development of electrode active materials using organic radical compounds have been actively conducted in recent years.

  In the organic radical compound, the unpaired electrons that react are localized in the radical atom, so that the concentration of the reaction site can be increased, and thus a high-capacity secondary battery can be realized. Further, since the reaction rate of radicals is high, it is considered that the charging time can be completed in a short time by performing charging / discharging utilizing a redox reaction of a stable radical.

  Patent Document 1 discloses a secondary battery active material using a nitroxyl radical compound, an oxy radical compound, and a nitrogen radical compound having a radical on a nitrogen atom.

  This Patent Document 1 describes an example using a highly stable nitroxyl radical as a radical. For example, a secondary battery using an electrode layer containing a nitronyl nitroxide compound as a positive electrode and a lithium-bonded copper foil as a negative electrode. After repeatedly charging and discharging, it was confirmed that charging and discharging was possible over 10 cycles or more.

  Patent Document 2 proposes an electrode containing a compound having a diazine N, N′-dioxide structure as an electrode active material, and Patent Document 3 discloses a diazine N, N′-dioxide structure as a side chain. An electrode active material containing an oligomer or polymer compound is proposed.

  In Patent Documents 2 and 3, a diazine N, N′-dioxide compound or a polymer compound having a diazine N, N′-dioxide structure in the side chain functions as an electrode active material in the electrode, and discharge of the electrode reaction. In the reaction or charge / discharge reaction, it is contained in the electrode as a reaction starting material, product or intermediate product. Then, five different states can be obtained by exchanging electrons in the oxidation-reduction reaction, and it is considered that a multi-electron reaction in which two or more electrons participate in the reaction is also possible.

JP 2004-207249 A (paragraph numbers [0278] to [0282]) JP 2003-115297 A (Claim 1, paragraph numbers [0038], [0039]) JP 2003-242980 A (Claim 1, paragraph numbers [0044], [0045])

  However, Patent Document 1 uses an organic radical compound such as a nitroxyl radical compound as an electrode active material, but the charge / discharge reaction is limited to a one-electron reaction involving only one electron. The reason is that when a multi-electron reaction involving two or more electrons is caused, the radical lacks stability and decomposes, and the radical disappears and the reversibility of the charge / discharge reaction is lost.

  In Patent Documents 2 and 3, it is considered that a multi-electron reaction of two or more electrons is possible. However, according to the research results of the present inventors, the stability in the oxidized state and the reduced state is not sufficient, and the cycle characteristics are low. It was found that when the charge / discharge cycle was repeated, the energy density significantly decreased in a short period because it was bad.

  The present invention has been made in view of such circumstances, and provides an electrode active material and a secondary battery that have high energy density, high output, and good cycle characteristics with little decrease in capacity even after repeated charge and discharge. For the purpose.

  The inventors of the present invention have made extensive studies to achieve the above object. As a result, the organic compound having a diamine structure in the structural unit is excellent in stability in an oxidized state and a reduced state, and is obtained by a redox reaction. It has been found that a multi-electron reaction of two electrons or more is possible, a large amount of electricity can be charged even with a small molecular weight, and a high capacity density electrode active material can be obtained.

  The present invention has been made based on such knowledge, and the electrode active material according to the present invention is an electrode active material used as an active material of a secondary battery that repeats charge and discharge by a battery electrode reaction, and includes a diamine. It is characterized by mainly comprising an organic compound having a structure in a structural unit.

  In the electrode active material of the present invention, the organic compound has the general formula

[Wherein, R ₁ and R ₂ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, From a substituted or unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and combinations of one or more thereof Any one of the following linking groups is shown. X _{1 to} X ₄ are a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkyl group, Substituted or unsubstituted aryl group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy At least one of a group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted aryloxycarbonyl group, a substituted or unsubstituted acyl group, and a substituted or unsubstituted acyloxy group, and these substituents Includes the case where a substituent forms a ring structure. ]
It has the conjugated diamine structure represented by these.

  Further, in the electrode active material of the present invention, the organic compound has the general formula

[Wherein R ₃ and R ₄ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group; Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, From a substituted or unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and combinations of one or more thereof Any one of the following linking groups is shown. X _{5 to} X ₁₂ are each a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkyl group, Substituted or unsubstituted aryl group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy Group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted aryloxycarbonyl group, substituted or unsubstituted acyl group, and substituted or unsubstituted acyloxy group. Including the case of forming a structure. ]
It has the phenazine structure represented by these.

  In the electrode active material of the present invention, the organic compound has the general formula

[Wherein, R ₅ and R ₆ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group, Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, From a substituted or unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and combinations of one or more thereof Any one of the following linking groups is shown. ]
It has the phenazine structure represented by these.

  In the secondary battery according to the present invention, any of the electrode active materials described above is included in at least one of a reaction starting material, a product, and an intermediate product in the discharge reaction of the battery electrode reaction. It is characterized by.

  Furthermore, the secondary battery of the present invention has a positive electrode, a negative electrode, and an electrolyte, and the positive electrode is mainly composed of the electrode active material.

  According to the electrode active material of the present invention, the main component is an organic compound having a diamine structure typified by a conjugated diamine structure or a phenazine structure in the structural unit, so that it is stable during charge and discharge, that is, in an oxidized state and a reduced state. In addition, a multi-electron reaction of two electrons or more is possible by an oxidation-reduction reaction, and a large amount of electricity can be charged even with a small molecular weight, whereby a high capacity density electrode active material can be obtained.

  In addition, according to the secondary battery of the present invention, since the electrode active material is used, both the multi-electron reaction and the stability with respect to the charge / discharge cycle can be achieved, the energy density is large, the output is high, and the charge / discharge is repeated. However, it is possible to obtain a long-life secondary battery with good cycle characteristics with little reduction in capacity.

  In addition, since the electrode active material is mainly composed of organic compounds, the environmental load is low and safety is taken into consideration.

It is sectional drawing which shows one Embodiment of the coin-type battery as a secondary battery which concerns on this invention.

  Next, an embodiment of the present invention will be described in detail.

  The electrode active material according to the present invention is mainly composed of an organic compound having a diamine structure in the structural unit. As a result, the stability in the oxidized state and reduced state during charge / discharge can be improved, and an electrode active material having a high capacity density can be obtained.

  If the electrode active material of this invention contains the organic compound which has a diamine structure in a structural unit, organic compound seed | species will not be specifically limited, However, Conjugated diamine as shown in following General formula (1) The structure is preferably included in the structural unit.

R ₁ and R ₂ are substituted or unsubstituted alkyl groups, substituted or unsubstituted alkylene groups, substituted or unsubstituted arylene groups, substituted or unsubstituted carbonyl groups, substituted or unsubstituted acyl groups, substituted Or an unsubstituted alkoxycarbonyl group, a substituted or unsubstituted ester group, a substituted or unsubstituted ether group, a substituted or unsubstituted thioether group, a substituted or unsubstituted amine group, a substituted or unsubstituted amide group, substituted or A linkage comprising an unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and one or more combinations thereof Indicates one of the groups. X _{1 to} X ₄ are a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkyl group, Substituted or unsubstituted aryl group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy At least one of a group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted aryloxycarbonyl group, a substituted or unsubstituted acyl group, and a substituted or unsubstituted acyloxy group, and these substituents Includes the case where a substituent forms a ring structure.

  An organic compound having such a conjugated diamine structure in the structural unit is excellent in stability in an oxidized state and a reduced state, and can charge a large amount of electricity even with a small molecular weight. An active material can be obtained.

  Each of the substituents listed above is not limited as long as it belongs to each category. However, as the molecular weight increases, the amount of charge that can be accumulated per unit mass of the electrode active material decreases. It is preferable to select a desired substituent so as to be about 250.

  Moreover, as an organic compound which has a diamine structure in a structural unit, it is also preferable to use the organic compound which contains the phenazine structure as shown in following General formula (2) in a structural unit other than the conjugated diamine structure mentioned above.

Here, R ₃ and R ₄ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group, Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, substituted Or an unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and a combination of one or more of these One of the linking groups is shown. X _{5 to} X ₁₂ are each a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkyl group, Substituted or unsubstituted aryl group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy Group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted aryloxycarbonyl group, substituted or unsubstituted acyl group, and substituted or unsubstituted acyloxy group. Includes the case of forming a structure.

  Among organic compounds having a phenazine structure in the structural unit, an organic compound in which a carbonyl group (—CO) is bonded to one N atom of the pyrazine ring is used as shown in the following general formula (3). preferable.

Here, R ₅ and R ₆ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group, Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, substituted Or an unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and a combination of one or more of these One of the linking groups is shown.

  And as an organic compound which has such a phenazine structure in a structural unit, the organic compound shown to Chemical formula (4)-(10) can be mentioned, for example.

  The molecular weight of the organic compound constituting the electrode active material is not particularly limited. However, when the portion other than the diamine structure is increased, the molecular weight is increased, so that the storage capacity per unit mass, that is, the capacity density is reduced. Accordingly, the molecular weight of the portion other than the diamine structure is preferably small.

  In addition, as shown in the chemical formulas (7) to (10), a polymer or copolymer of an organic compound having a phenazine structure in a structural unit can be used, and even in such a case, the molecular weight or molecular weight distribution can be used. Is not particularly limited.

The electrode active material is considered to generate cations with an electrochemical oxidation reaction. The chemical reaction formula (11) shows an example of a charge / discharge reaction when an organic compound having a phenazine structure is used as an electrode active material and phosphorus hexafluoride ion (PF ₆ ⁻ ) is used as an anion of an electrolyte salt.

  As can be seen from the chemical reaction formula (11), two electrons per molecule of the organic compound (I) having a phenazine structure are involved in the reaction to generate a cation (II). In comparison, the capacity density can be increased.

  As described above, since the electrode active material of the present embodiment is mainly composed of an organic compound having a diamine structure represented by a conjugated diamine structure or a phenazine structure in a structural unit, it is charged and discharged, that is, in an oxidized state and a reduced state. It is possible to obtain a high-capacity electrode active material by being able to charge a large amount of electricity even with a small molecular weight. it can.

  Next, a secondary battery using the electrode active material will be described in detail.

  FIG. 1 is a cross-sectional view showing a coin-type secondary battery as an embodiment of a secondary battery according to the present invention. In this embodiment, the electrode active material of the present invention is used as a positive electrode active material. ing.

  The battery can 1 has a positive electrode case 2 and a negative electrode case 3, and both the positive electrode case 2 and the negative electrode case 3 are formed in a disk-like thin plate shape. And the positive electrode 4 which formed the electrode active material in the sheet form is distribute | arranged to the center of the bottom part of the positive electrode case 2 which comprises a positive electrode electrical power collector. A separator 5 made of a porous film such as polypropylene is laminated on the positive electrode 4, and a negative electrode 6 is further laminated on the separator 5. As the negative electrode 6, for example, one obtained by superimposing a lithium metal foil on Cu or one obtained by applying a lithium storage material such as graphite or hard carbon to the metal foil can be used. A negative electrode current collector 7 made of Cu or the like is laminated on the negative electrode 6, and a metal spring 8 is placed on the negative electrode current collector 7. The electrolyte 9 is filled in the internal space, and the negative electrode case 3 is fixed to the positive electrode case 2 against the urging force of the metal spring 8 and sealed with a gasket 10.

  Next, an example of a method for manufacturing the secondary battery will be described in detail.

  First, an electrode active material is formed into an electrode shape. For example, the electrode active material is mixed with a conductive auxiliary agent and a binder, and a solvent is added to form a slurry. The slurry is applied on the positive electrode current collector by an arbitrary coating method, and dried to obtain the positive electrode. Form.

  Here, the conductive auxiliary agent is not particularly limited, and examples thereof include carbonaceous fine particles such as graphite, carbon black, and acetylene black, carbon fibers such as vapor grown carbon fiber (VGCF), carbon nanotube, and carbon nanohorn. , Conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene can be used. Further, two or more kinds of conductive assistants can be mixed and used. In addition, as for the content rate in the positive electrode 4 of a conductive support agent, 10 to 80 weight% is preferable.

  Further, the binder is not particularly limited, and various resins such as polyethylene, polyvinylidene fluoride, polyhexafluoropropylene, polytetrafluoroethylene, polyethylene oxide, carboxymethylcellulose, and the like can be used.

  Further, the solvent is not particularly limited, and examples thereof include basic solvents such as dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, propylene carbonate, diethyl carbonate, dimethyl carbonate, and γ-butyrolactone, acetonitrile, tetrahydrofuran, and nitrobenzene. , Non-aqueous solvents such as acetone, and protic solvents such as methanol and ethanol can be used.

  Moreover, the kind of solvent, the compounding ratio of the organic compound and the solvent, the kind of additive and the amount of the additive, and the like can be arbitrarily set in consideration of the required characteristics and productivity of the secondary battery.

  Next, the positive electrode 4 is impregnated in the electrolyte 9 so that the positive electrode 4 is impregnated with the electrolyte 9, and then the positive electrode 4 is placed on the positive electrode current collector at the bottom center of the positive electrode case 2. Next, the separator 5 impregnated with the electrolyte 9 is laminated on the positive electrode 4, the negative electrode 6 and the negative electrode current collector 7 are sequentially laminated, and then the electrolyte 9 is injected into the internal space. Then, a metal spring 8 is placed on the negative electrode current collector 9 and a gasket 10 is arranged on the periphery, and the negative electrode case 3 is fixed to the positive electrode case 2 by a caulking machine or the like, and the outer casing is sealed. A type secondary battery is produced.

The electrolyte 9 is interposed between the positive electrode (electrode active material) 4 and the negative electrode 6 which is the counter electrode, and transports charge carriers between the two electrodes. Those having an electric conductivity of ⁻⁵ to 10 ⁻¹ S / cm can be used. For example, an electrolytic solution in which an electrolyte salt is dissolved in an organic solvent can be used.

Here, as the electrolyte salt, for example, LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ , Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C, Li (C ₂ F ₅ SO ₂ ) ₃ C, or the like can be used.

  As the organic solvent, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, etc. are used. be able to.

  The electrolyte 9 may be a solid electrolyte. Examples of the polymer compound used for the solid electrolyte include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-monofluoroethylene copolymer, and fluoride. Vinylidene fluoride polymers such as vinylidene-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, and acrylonitrile-methyl methacrylate copolymer Polymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-ethyl methacrylate copolymer, acrylonitrile-ethyl acrylate copolymer, acrylonitrile-methacrylic acid copolymer, acrylonitrile-acrylic Acrylic nitrile polymers such as formic acid copolymers, acrylonitrile-vinyl acetate copolymers, polyethylene oxide, ethylene oxide-propylene oxide copolymers, and polymers of these acrylates and methacrylates Can do. Further, these polymer compounds containing an electrolytic solution in a gel form may be used as the electrolyte 9 or only a polymer compound containing an electrolyte salt may be used as the electrolyte 9 as it is.

  Since the electrode active material of the secondary battery is reversibly oxidized or reduced by charge and discharge, it has a different structure and state depending on the charged state, discharged state, or intermediate state. The active material is contained in at least one of a reaction starting material in the discharge reaction (a material that causes a chemical reaction in the battery electrode reaction), a product (a material resulting from the chemical reaction), and an intermediate product. And the said discharge reaction has at least 2 or more discharge voltage, It is possible to implement | achieve the battery of the high capacity | capacitance density over several voltage by this.

  Thus, according to the present embodiment, the secondary battery is configured using the electrode active material that is excellent in stability with respect to the charge / discharge cycle and in which multiple electrons of two or more electrons are involved in the reaction. It is possible to obtain a long-life secondary battery having a large energy density, high output, and good cycle characteristics with little decrease in capacity even after repeated charge and discharge.

  In addition, since the electrode active material is mainly composed of organic compounds, the environmental load is low and safety is taken into consideration.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from a summary. For example, the above-listed chemical formulas (4) to (10) are also examples of the organic compound that is the main component of the electrode active material, and the present invention is not limited thereto. That is, if at least the diamine structure is included in the structural unit, the oxidation-reduction reaction shown in the chemical reaction formula (11) is considered to proceed, so that a secondary battery having a large energy density and excellent stability can be obtained. Is possible.

  In the above embodiment, the coin-type secondary battery has been described. However, the battery shape is not particularly limited, and can be applied to a cylindrical type, a square type, a sheet type, and the like. Also, the exterior method is not particularly limited, and a metal case, mold resin, aluminum laminate film, or the like may be used.

  Moreover, in the said embodiment, although the organic compound which has a diamine structure in a structural unit was used for the positive electrode active material, using for a negative electrode active material is also useful.

  Next, examples of the present invention will be specifically described.

  In addition, the Example shown below is an example and this invention is not limited to the following Example.

(Synthesis of organic compounds)
According to the synthesis scheme (A), N, N′-bis (ethoxycarbonyl) -5,10-dihydrophenazine (4) was synthesized.

First, 28 mmol of phenazine was dissolved in 150 mL of ethanol, and Na ₂ S ₂ O ₄ dissolved in 150 mL of pure water was added dropwise in an argon stream, followed by stirring for 3 hours to precipitate 5,10-dihydrophenazine (4B). I let you. Next, the precipitated 5,10-dihydrophenazine (4B) was filtered off, washed with pure water, and dried under reduced pressure. Next, 7.7 mmol of 5,10-dihydrophenazine (4B) and 25 mL of ethyl chloroformate (4C) were dried in an argon stream at 80 ° C. for 5 hours, and unreacted ethyl chloroformate (4C) was removed. After removal, recrystallization from methanol gave N, N′-bis (ethoxycarbonyl) -5,10 dihydrophenazine (4).

[Production of secondary battery]
N, N′-bis (ethoxycarbonyl) -5,10-dihydrophenazine: 300 mg, graphite powder as a conductive auxiliary agent: 600 mg, polytetrafluoroethylene resin as a binder: 100 mg were weighed, respectively, The mixture was kneaded while mixing so as to be uniform.

  Next, this mixture was pressure-molded to produce a sheet-like member having a thickness of about 150 μm. Next, this sheet-like member was dried in a vacuum at 80 ° C. for 1 hour, then punched into a circle having a diameter of 12 mm, and a positive electrode mainly composed of N, N′-bis (ethoxycarbonyl) -5,10-dihydrophenazine ( A positive electrode active material) was prepared.

Next, the positive electrode was impregnated with an electrolytic solution, and the electrolytic solution was infiltrated into voids in the positive electrode. As the electrolytic solution, an ethylene carbonate / diethyl carbonate mixed solution which is an organic solvent containing lithium hexafluorophosphate (LiPF ₆ ) (electrolyte salt) having a molar concentration of 1.0 mol / L was used. In addition, the mixing ratio of ethylene carbonate and diethyl carbonate was ethylene carbonate: diethyl carbonate = 3: 7 by volume%.

  Next, this positive electrode was placed on a positive electrode current collector, a separator having a thickness of 20 μm made of a polypropylene porous film impregnated with the electrolytic solution was further laminated on the positive electrode, and lithium was further formed on both sides of the copper foil. The negative electrode to which was attached was laminated on the separator. And after laminating | stacking the negative electrode collector made from Cu on a negative electrode, inject | pouring electrolyte solution into interior space, and mounting a metal spring on a negative electrode collector after that, and having arrange | positioned the gasket to the periphery The negative electrode case is bonded to the positive electrode case and sealed with a caulking machine, thereby having N, N′-bis (ethoxycarbonyl) -5,10-dihydrophenazine as the positive electrode active material and metallic lithium as the negative electrode active material. A sealed coin-type battery was produced.

[Confirmation of secondary battery operation]
The secondary battery produced as described above was charged with a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.5 V with a constant current of 0.1 mA. As a result, it was confirmed that the secondary battery had a discharge capacity of 0.2 mAh having a voltage flat portion at two places of charge / discharge voltages of 2.8 V and 2.5 V.

  And when the capacity density per electrode active material was computed from this discharge capacity, it was 160 Ah / kg.

  On the other hand, the theoretical capacity density Q (Ah / kg) of the secondary battery is expressed by Equation (1).

  Here, Z is the number of electrons involved in the battery electrode reaction, and W is the molecular weight of the electrode active material. Since the molecular weight of N, N′-bis (ethoxycarbonyl) -5,10-dihydrophenazine is 326.35, assuming that the number of electrons Z involved in the battery electrode reaction is 2, the theoretical capacity density can be calculated from Equation (1). Q is 164 Ah / kg. Therefore, it was confirmed that N, N′-bis (ethoxycarbonyl) -5,10-dihydrophenazine has a multi-electron reaction involving at least two electrons per repeating unit.

  In addition, a charge / discharge cycle test was performed in which a similarly manufactured secondary battery was charged at a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.5 V at a constant current of 0.1 mA. As a result, the discharge capacity after 100 cycles was hardly different from the initial capacity, and could be maintained at 80% or more. That is, a secondary battery having a long charge / discharge cycle life and excellent stability could be obtained.

(Synthesis of organic compounds)
Using 5,10-dihydrophenazine synthesized in Example 1 as a starting material, a polymer of a dihydrophenazine carbonyl compound was synthesized according to Synthesis Scheme (B).

That is, 30 mmol of 5,10-dihydrophenazine (7A) was dissolved in dichloromethane in the presence of triethylamine ((C ₂ H ₅ ) ₃ N), and triphosgene (Cl ₃ CO) was stirred in a vessel equipped with a trap. _The gas generated from ₂ CO) was blown. That is, when triphosgene is allowed to act on triethylamine to decompose triphosgene, three molecules of phosgene are generated. Then, 5,10-dihydrophenazine (7A) and phosgene are stirred in a reaction vessel for 6 hours and reacted with each other, and then the reaction product is purified to obtain a polymer of dihydrophenazine carbonyl compound that is a dark brown solid. (7) was obtained.

[Production of secondary battery]
A secondary battery was fabricated in the same manner as in [Example 1] except that a polymer of a dihydrophenazine carbonyl compound was used as the electrode active material.

[Confirmation of secondary battery operation]
The secondary battery produced as described above was charged with a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.5 V with a constant current of 0.1 mA. As a result, it was confirmed that the secondary battery had a discharge capacity of 0.22 mAh having a voltage flat portion at two places of charge / discharge voltages of 2.7 V and 2.2 V.

  And when the capacity density per electrode active material was computed from this discharge capacity, it was 245 Ah / kg.

  On the other hand, since the molecular weight per repeating unit of the polymer of the dihydrophenazine carbonyl compound is 225.3, when the number of electrons Z involved in the battery electrode reaction is 2, the theoretical capacity density is 238 Ah / kg from the above formula (1). It becomes. Therefore, it was confirmed that the polymer of the dihydrophenazine carbonyl compound has a multi-electron reaction involving at least two electrons per repeating unit.

  In addition, a charge / discharge cycle test was performed in which a similarly manufactured secondary battery was charged at a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.5 V at a constant current of 0.1 mA. As a result, the discharge capacity after 100 cycles was hardly different from the initial capacity, and could be maintained at 80% or more. That is, a secondary battery having a long charge / discharge cycle life and excellent stability could be obtained.

(Preparation of organic compound)
A 5,10-dihydrodimethylphenazine made by Kanto Chemical Co. represented by the following chemical formula (5) was prepared, and the 5,10-dihydrodimethylphenazine was dried under reduced pressure at 80 ° C. for 30 minutes, thereby obtaining an electrode active material. .

[Production of secondary battery]
A secondary battery was fabricated in the same manner as in [Example 1] except that 5,10-dihydrodimethylphenazine was used as the electrode active material.

[Confirmation of secondary battery operation]
The secondary battery fabricated as described above was charged with a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.8 V with a constant current of 0.1 mA. As a result, it was confirmed that the secondary battery had a discharge capacity of 0.12 mAh having a voltage flat portion at two places where the charge / discharge voltages were 2.8 V and 2.0 V.

  And when the capacity density per electrode active material was computed from this discharge capacity, it was 170 Ah / kg.

  On the other hand, since the molecular weight of 5,10-dihydrodimethylphenazine is 210.3, when the number of electrons Z involved in the battery electrode reaction is 2, the theoretical capacity density is 255 Ah / kg from the above formula (1), and the number of electrons When Z is 1, the theoretical capacity density is 127.4 Ah / kg. Therefore, it was confirmed that 5,10-dihydrodimethylphenazine is undergoing a multi-electron reaction involving more than one electron per repeating unit.

  In addition, a charge / discharge cycle test was performed in which a similarly manufactured secondary battery was charged at a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.5 V at a constant current of 0.1 mA. As a result, the discharge capacity after 100 cycles was hardly different from the initial capacity, and could be maintained at 80% or more. That is, a secondary battery having a long charge / discharge cycle life and excellent stability could be obtained.

(Synthesis of organic compounds)
According to the synthesis scheme (C), a polymer of a dihydrophenazine dicarbonyl compound was synthesized.

First, diethyl carbonate (8B) and phenazine (8A) containing 1 mol / L LiPF ₆ were put into an H-type cell for an electrolytic reaction having electrodes and partition walls, and 0.25 mol / L N, N′-bis ( Ethoxycarbonyl) -5,10-disidrophenazine (8C) was prepared.

  Next, electricity was applied between the two electrodes of the H-type cell, and a voltage of 1.5 V was applied. Energization was stopped after 3 hours, and then a voltage of 4.4 V was applied and held for 3 hours. The voltage application of 1.5V and 4.4V was alternately repeated 10 times to obtain a black solid reaction product. The reaction product was then filtered off and dried to obtain a solid comprising a black polymer (8) of a dihydrophenazine dicarbonyl compound.

[Production of secondary battery]
A secondary battery was produced in the same manner as in [Example 1] except that the polymer of the dihydrophenazine dicarbonyl compound was used as the electrode active material.

[Confirmation of secondary battery operation]
The secondary battery produced as described above was charged with a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.8 V with a constant current of 0.1 mA. As a result, it was confirmed that the secondary battery had a discharge capacity of 0.20 mAh having a voltage flat portion at two places where the charge / discharge voltages were 2.8 V and 2.4 V.

  And when the capacity density per electrode active material was computed from this discharge capacity, it was 240 Ah / kg.

  On the other hand, the molecular weight per repeating unit of the polymer of the dihydrophenazine dicarbonyl compound is 236, and when the number of electrons Z involved in the battery electrode reaction is 2, the theoretical capacity density is 227 Ah / kg from Equation (1). Therefore, it was confirmed that the polymer of the dihydrophenazine dicarbonyl compound has a multi-electron reaction involving at least two electrons per repeating unit.

  In addition, a charge / discharge cycle test was performed in which a similarly manufactured secondary battery was charged at a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.5 V at a constant current of 0.1 mA. As a result, the discharge capacity after 100 cycles was hardly different from the initial capacity, and could be maintained at 80% or more. That is, a secondary battery having a long charge / discharge cycle life and excellent stability could be obtained.

Comparative Example 1

(Synthesis of organic compounds)
According to the synthesis scheme (D), phenazine-5,10-dioxide having a diazine N, N′-dioxide structure was synthesized.

First, phenazine (100A) was dissolved in an aqueous solution containing acetic acid (CH ₃ COOH) and hydrogen peroxide (H ₂ O ₂ ), and stirred at 65 ° C. for 48 hours. The obtained product was dissolved in dichloromethane (CH ₂ Cl ₂ ), concentrated with an evaporator, recrystallized in a cool dark place, dried, and dried to form phenazine-5,10-dioxide (100 )

[Production of secondary battery]
A secondary battery was fabricated in the same manner as in [Example 1] except that phenazine-5,10-dioxide was used as the electrode active material.

[Confirmation of secondary battery operation]
The secondary battery produced as described above was charged with a constant current of 0.1 mA until the voltage reached 4.0 V, and then discharged to 1.8 V with a constant current of 0.1 mA. As a result, voltage flat portions were observed at three locations where the charge / discharge voltage was 2.6 V, 2.1 V and 1.9 V only for the first time, but the voltage flat portion disappeared after the second cycle and the capacity was also 1 / It decreased to 5 or less, and it turned out that it is not suitable for a secondary battery.

  An electrode active material and a secondary battery having a large energy density, high output, and good cycle characteristics with little decrease in capacity even after repeated charge and discharge are realized.

4 Positive electrode 6 Negative electrode 9 Electrolyte

Claims (6)

An electrode active material used as an active material of a secondary battery that repeats charging and discharging by a battery electrode reaction,
An electrode active material mainly comprising an organic compound having a diamine structure in a structural unit. The organic compound has the general formula

[Wherein, R ₁ and R ₂ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, From a substituted or unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and combinations of one or more thereof Any one of the following linking groups is shown. X _{1 to} X ₄ are a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkyl group, Substituted or unsubstituted aryl group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy At least one of a group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted aryloxycarbonyl group, a substituted or unsubstituted acyl group, and a substituted or unsubstituted acyloxy group, and these substituents Includes the case where a substituent forms a ring structure. ]
The electrode active material according to claim 1, which has a conjugated diamine structure represented by: The organic compound has the general formula

[Wherein R ₃ and R ₄ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group; Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, From a substituted or unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and combinations of one or more thereof Any one of the following linking groups is shown. X _{5 to} X ₁₂ are each a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted cycloalkyl group, Substituted or unsubstituted aryl group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted amino group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aryloxy Group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted aryloxycarbonyl group, substituted or unsubstituted acyl group, and substituted or unsubstituted acyloxy group. Including the case of forming a structure. ]
The electrode active material according to claim 1, which has a phenazine structure represented by: The organic compound has the general formula

[Wherein, R ₅ and R ₆ are a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted acyl group, Substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted ester group, substituted or unsubstituted ether group, substituted or unsubstituted thioether group, substituted or unsubstituted amine group, substituted or unsubstituted amide group, From a substituted or unsubstituted sulfone group, a substituted or unsubstituted thiosulfonyl group, a substituted or unsubstituted sulfonamido group, a substituted or unsubstituted imine group, a substituted or unsubstituted azo group, and combinations of one or more thereof Any one of the following linking groups is shown. ]
The electrode active material according to claim 1, which has a phenazine structure represented by:   The electrode active material according to any one of claims 1 to 4 is included in any one of a reaction starting material, a product, and an intermediate product in at least a discharge reaction of the battery electrode reaction. Secondary battery.   The secondary battery according to claim 5, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode is mainly composed of the electrode active material.

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