Active material for secondary battery, electrode for secondary battery, secondary battery, and aircraft

Abstract

To provide an active material for a secondary battery capable of further improving the energy density of a power storage cell, a secondary battery, and a flying object using a secondary battery.SOLUTION: An active material used for a secondary battery includes a heterocyclic compound including one or more pyrazine rings and two or more benzene rings, or a salt or a derivative thereof. The heterocyclic compound is preferably a compound in which at least four oxygen atoms are coupled to the above benzene ring. The active material used for a secondary battery may contain phenazine or a salt or a derivative thereof. The phenazines are preferably a compound in which at least four oxygen atoms are coupled to the benzene ring in the phenazine structure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an active material for a secondary battery, an electrode for a secondary battery, a secondary battery, and an aircraft.

Background Art

[0002] Patent Document 1 discloses an electrode active material for a non-aqueous secondary battery composed of a compound in which a naphthalazine skeleton is condensed with a non-conjugated ring such as a dithiin ring as an organic material exhibiting redox activity. By using the electrode active material for a non-aqueous secondary battery described in Patent Document 1, a storage cell having an energy density of about 400 [Wh / kg - storage cell] can be produced. However, further improvement in the energy density of the storage cell is desired. [Prior Art Document] [Patent Document] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2018-085243

Summary of the Invention

[0003] In a first aspect of the present invention, there is provided an active material for a secondary battery, which is an active material used in a secondary battery. The above active material includes, for example, a compound represented by the following general formula (1), general formula (2), general formula (3), general formula (4), general formula (4), general formula (5), general formula (6), or general formula (7), or a salt thereof.

[0004] [General formula (1)]

Chemical formula

[0005] [General formula (2)] [Chemical formula] [In general formula (2), R 201 ~R 210 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 201 ~R 210 are linked to each other to form a ring represented by -OMO-. The double lines shown by solid lines and broken lines represent a single bond or a double bond. At least four of R 201 ~R 210 are an oxygen atom or a group represented by -OM.

[0006] [General formula (3)] [Chemical formula] [In general formula (3), R 301 ~R 310 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 301 ~R 310 are linked to each other to form a ring represented by -OMO-. The double lines shown by solid lines and broken lines represent a single bond or a double bond. At least four of R 301 ~R 310 are an oxygen atom or a group represented by -OM.

[0007] [General formula (4)] [Chemical formula] [In general formula (4), R 401 ~R 410Each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 401 ~R 410 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond. At least four of R 401 ~R 410 are an oxygen atom or a group represented by -OM. 〕

[0008] [General formula (5)] [Chemical formula] 〔In general formula (5), R 501 ~R 512 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 501 ~R 512 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond. At least four of R 501 ~R 512 are an oxygen atom or a group represented by -OM. 〕

[0009] [General formula (6)] [Chemical formula] 〔In general formula (6), R 601 ~R 612 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 601 ~R 612 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond. At least four of R 601 ~R 612At least four of them are an oxygen atom or a group represented by -OM.

[0010] [General formula (7)] [Chemical formula] 〔In general formula (7), R 701 ~R 712 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 701 ~R 712 are linked to each other to form a ring represented by -OMO-. The double lines shown by solid lines and broken lines represent single bonds or double bonds. At least four of R 701 ~R 712 are an oxygen atom or a group represented by -OM.〕

[0011] In the above active material, the above compound may have symmetry. In the above active material, the above compound may be the following compound, or its complete reduction product or partial reduction product. In the following chemical formula, R 1 and R 2 each independently represents a hydrogen atom or an organic group. [Chemical formula]

[0012] In the second aspect of the present invention, there is provided an active material for a secondary battery, which is an active material used in a secondary battery. The above active material includes, for example, a polymer containing a repeating unit represented by the following general formula (8), general formula (9), general formula (10) or general formula (11), or a salt thereof.

[0013] [General formula (8)] [Chemical formula] 〔In general formula (8), R 801 ~R806 Each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 801 ~R 806 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. At least four of R 801 ~R 806 are an oxygen atom or a group represented by -OM. n is an integer of 2 or more indicating the degree of polymerization. ]]

[0014] [General formula (9)] [Chemical formula] [In general formula (9), R 101 ~R 104 each independently represents an oxygen atom or a group represented by -OM. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 101 ~R 104 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. n is an integer of 2 or more indicating the degree of polymerization. ]]

[0015] [General formula (10)] [Chemical formula] [In general formula (10), R 201 ~R 206 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 201 ~R 206 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. R 201 ~R 206At least four of them are an oxygen atom or a group represented by -OM. n is an integer of 2 or more indicating the degree of polymerization.

[0016] [General formula (11)] [Chemical formula] [In general formula (11), R 501 ~R 508 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 501 ~R 508 are linked to each other to form a ring represented by -OMO-. The double lines shown by solid and broken lines represent a single bond or a double bond. At least four of R 501 ~R 508 are an oxygen atom or a group represented by -OM. n is an integer of 2 or more indicating the degree of polymerization.

[0017] The above active material may include a polymer containing a repeating unit represented by the following chemical formula (8-1) or a salt thereof. [Chemical formula 8-1] [Chemical formula] [In chemical formula (8-1), n is an integer of 2 or more indicating the degree of polymerization.

[0018] In the active material for a secondary battery according to the above first aspect and second aspect, M may be H, Li, Na, K, Mg or Ca.

[0019] In the third aspect of the present invention, an electrode for a secondary battery is provided. The above electrode for a secondary battery includes, for example, the active material for a secondary battery according to the above first aspect and second aspect.

[0020] In a fourth aspect of the present invention, a secondary battery is provided. The secondary battery has, for example, a positive electrode active material layer containing a positive electrode active material, a negative electrode active material layer containing a negative electrode active material, and an electrolyte. In the secondary battery, the positive electrode active material or the negative electrode active material contains, for example, the active material for a secondary battery according to the first and second aspects described above.

[0021] In the secondary battery, the positive electrode active material may contain the active material for a secondary battery according to the first and second aspects described above. The secondary battery may be a non-aqueous secondary battery.

[0022] In a fourth aspect of the present invention, an aircraft is provided. The aircraft includes, for example, the secondary battery according to the first and second aspects described above. The aircraft includes, for example, a propulsion force generating device that generates propulsion force using the electrical energy stored in the secondary battery.

[0023] Note that the above summary of the invention does not list all the necessary features of the present invention. Also, sub-combinations of these feature groups can also be inventions.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0025] According to this embodiment, as an active material for a secondary battery, a heterocyclic compound containing one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof is used. Examples of derivatives of a specific organic compound include compounds in which, when considering the organic compound as a parent, modifications such as introduction of functional groups, oxidation, reduction, and replacement of atoms are made to such an extent that the structure and properties of the parent are not significantly changed. The above heterocyclic compound is preferably a compound in which at least four oxygen atoms are bonded to the above benzene ring. As an active material for a secondary battery, phenazine or a salt or derivative thereof (which may be referred to as phenazines) may be used. The above phenazines are preferably compounds in which at least four oxygen atoms are bonded to the benzene ring contained in the phenazine structure.

[0026] Further, according to this embodiment, there are provided an electrode for a secondary battery containing the above active material, a secondary battery containing the electrode for a secondary battery, and an aircraft containing the secondary battery. As described above, in this embodiment, the active material contains one or more pyrazine rings and two or more benzene rings in at least a part of its structure. Further, at least four oxygen atoms are bonded to the above two or more benzene rings. Thereby, the capacity per unit mass [mAh / g - active material] of the active material is improved. As a result, for example, a power storage cell having an energy density per unit mass of 500 [Wh / kg - power storage cell] or more can be obtained. A secondary battery including the power storage cell according to this embodiment has a large energy density per unit mass, and thus is particularly suitable for use in an aircraft.

[0027] Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. Also, not all combinations of features described in the embodiments are essential for the solution means of the invention.

[0028] In this specification, when a numerical range is expressed as "A to B", this expression means A or more and B or less. Also, "substituted or unsubstituted" means "substituted with any substituent or not substituted with a substituent". The type of the above-mentioned substituent is not particularly limited unless otherwise mentioned in the specification. Also, the number of the above-mentioned substituents is not particularly limited unless otherwise mentioned in the specification.

[0029] FIG. 1 schematically shows an example of the system configuration of the aircraft 100. In the present embodiment, the aircraft 100 includes a storage battery 110, a power control circuit 120, one or more electric motors 130, one or more propellers 140, one or more sensors 150, and a control device 160. In the present embodiment, the storage battery 110 has one or more storage cells 112.

[0030] In the present embodiment, the aircraft 100 flies using the electrical energy stored in the storage battery 110. Examples of the aircraft 100 include airplanes, airships or balloons, balloons, helicopters, drones, and the like.

[0031] In the present embodiment, the storage battery 110 receives electrical energy from an external charging device (not shown) via the power control circuit 120 and stores the electrical energy in one or more storage cells 112. Also, the storage battery 110 supplies the electrical energy stored in one or more storage cells 112 to the electric motor 130 via the power control circuit 120.

[0032] In the present embodiment, the storage cell 112 stores electrical energy (which may be referred to as charging of the storage cell 112). Also, the storage cell 112 discharges the stored electrical energy (which may be referred to as discharging of the storage cell 112). The storage cell 112 may be a secondary battery. The storage cell 112 may be a non-aqueous secondary battery.

[0033] Examples of non-aqueous secondary batteries include sodium-ion secondary batteries, lithium-ion secondary batteries, lithium metal secondary batteries, lithium-air secondary batteries, lithium-sulfur secondary batteries, magnesium-ion secondary batteries, aluminum-ion secondary batteries, and the like. Further, a lithium-ion secondary battery, which is one embodiment of a non-aqueous secondary battery, may be a concept including a non-aqueous lithium-ion secondary battery using a non-aqueous electrolyte and an all-solid-state lithium-ion secondary battery using a solid electrolyte.

[0034] For example, as an active material for a secondary battery mounted on a vehicle, a material with a large charge amount that can be stored per unit volume is often selected. On the other hand, in the present embodiment, the power storage cell 112 is mounted on the aircraft 100. Therefore, the active material used for the power storage cell 112 is preferably a material with a large charge amount that can be stored per unit mass.

[0035] The mass energy density of the power storage cell 112 is preferably 500 [Wh / kg-power storage cell] or more, more preferably 550 Wh / kg-power storage cell] or more, still more preferably 600 Wh / kg-power storage cell] or more, even more preferably 650 Wh / kg-power storage cell] or more, and even more preferably 700 [Wh / g-power storage cell] or more. Thereby, a power storage cell particularly suitable for use as a power source of an aircraft can be obtained.

[0036] The volume energy density of the power storage cell 112 may be 300 [Wh / m 3 -power storage cell] or more and 1200 [Wh / m 3 -power storage cell] or less, or may be 400 [Wh / m 3 -power storage cell] or more and 1000 [Wh / m 3 -power storage cell] or less. When the power storage cell 112 is mounted on the aircraft 100 as part of the power source of the aircraft 100, the volume energy density of the power storage cell 112 may be 600 [Wh / m 3 -power storage cell] or less, or may be 800 [Wh / m 3 -power storage cell] or less.

[0037] The storage cell 112 may have a mass energy density within the above numerical range and a volume energy density within the above numerical range. Thereby, a storage cell that is relatively difficult to use as a power source for a vehicle can be used as a power source for the aircraft. Details of the storage cell 112 will be described later.

[0038] In the present embodiment, the power control circuit 120 controls the input and output of the power of the storage battery 110. The power control circuit 120 may control the input and output of the power of the storage battery 110 based on an instruction from the control device 160. The power control circuit 120 includes, for example, a plurality of switching elements that operate based on a control signal from the control device 160.

[0039] In the present embodiment, the electric motor 130 receives electrical energy from the storage battery 110 via the power control circuit 120. The electric motor 130 uses the electrical energy received from the storage battery 110 to rotate the propeller 140. Thereby, the electric motor 130 can generate the propulsion force of the aircraft 100 by using the electrical energy stored in the storage cell 112.

[0040] In the present embodiment, the sensor 150 measures various physical quantities related to the position and attitude of the aircraft 100. Examples of sensors for measuring various physical quantities related to the position and attitude of the aircraft 100 include a GPS signal receiver, an acceleration sensor, an angular acceleration sensor, and a gyro sensor. The sensor 150 may measure various physical quantities related to the state of the storage battery 110. Examples of sensors for measuring various physical quantities related to the state of the storage battery 110 include a temperature sensor, a current sensor, and a voltage sensor.

[0041] In this embodiment, the control device 160 controls the flying object 100. The control device 160 may control the input and output of the power of the storage battery 110 by controlling the power control circuit 120. For example, the control device 160 controls the output current, output voltage, input current, input voltage, etc. of the storage battery 110. Thereby, the control device 160 can control the position and attitude of the flying object 100. The control device 160 may control the position and attitude of the flying object 100 by controlling the power control circuit 120 based on the output from the sensor 150.

[0042] The storage battery 110 may be an example of a secondary battery. The storage cell 112 may be an example of a secondary battery. The electric motor 130 may be an example of a propulsion force generating device.

[0043] FIG. 2 schematically shows an example of the storage cell 112. In this embodiment, the details of the storage cell 112 will be described by taking the case where the storage cell 112 is a coin-type non-aqueous secondary battery as an example.

[0044] [Storage Cell] In this embodiment, the storage cell 112 includes a positive electrode case 212, a negative electrode case 214, a sealing agent 216, and a metal spring 218. Further, the storage cell 112 includes a positive electrode 220, a separator 230, a negative electrode 240, and an electrolytic solution 250. In this embodiment, the positive electrode 220 has a positive electrode current collector 222 and a positive electrode active material layer 224. In this embodiment, the negative electrode 240 has a negative electrode current collector 242 and a negative electrode active material layer 244.

[0045] In this embodiment, by assembling the positive electrode case 212 and the negative electrode case 214, a space is formed inside the positive electrode case 212 and the negative electrode case 214. Inside the space formed by the positive electrode case 212 and the negative electrode case 214, the metal spring 218, the positive electrode 220, the separator 230, the negative electrode 240, and the electrolytic solution 250 are accommodated. The positive electrode 220, the separator 230, and the negative electrode 240 are fixed inside the positive electrode case 212 and the negative electrode case 214 by the repulsive force of the metal spring 218.

[0046] The positive electrode case 212 and the negative electrode case 214 are made of, for example, a conductive material having a disk-shaped thin plate shape. In the present embodiment, the sealing agent 216 seals the gap formed between the positive electrode case 212 and the negative electrode case 214. The sealing agent 216 contains an insulating material. The sealing agent 216 insulates the positive electrode case 212 and the negative electrode case 214.

[0047] [Positive electrode] In the present embodiment, the positive electrode current collector 222 holds the positive electrode active material layer 224. Examples of the material of the positive electrode current collector 222 include aluminum, stainless steel, nickel, titanium, or alloys thereof. Examples of the shape of the positive electrode current collector 222 include foil, mesh, punched metal, expanded metal, etc. The thickness of the positive electrode current collector 222 is not particularly limited, but is preferably 5 to 200 μm. The thickness of the positive electrode current collector 222 may be 6 to 20 μm.

[0048] In the present embodiment, the positive electrode active material layer 224 is formed on at least one surface of the positive electrode current collector 222. The thickness of the positive electrode active material layer 224 may be 1 to 300 μm or 2 to 200 μm per side of the positive electrode current collector 222. The positive electrode active material layer 224 contains, for example, a positive electrode active material and a binder (sometimes referred to as a binder). The positive electrode active material layer 224 may contain a conductive auxiliary agent.

[0049] In one embodiment, the positive electrode active material layer 224 is formed by applying a paste containing a material constituting the positive electrode active material layer 224 and an organic solvent onto at least one surface of the positive electrode current collector 222 and drying the paste. The type of the above organic solvent is not particularly limited, and examples of the above organic solvent include N-methylpyrrolidone (NMP). In other embodiments, the positive electrode active material layer 224 is formed by mixing the materials constituting the positive electrode active material layer 224 into a sheet shape and pressing the sheet-shaped mixture onto at least one surface of the positive electrode current collector 222.

[0050] The positive electrode active material layer 224 may contain, as the positive electrode active material, a heterocyclic compound containing one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof. The above heterocyclic compound may be a compound containing a phenazine structure. The phenazine structure includes (i) one pyrazine ring and two benzene rings, and (ii) each of the two benzene rings shares one carbon-carbon bond of the pyrazine ring with the pyrazine ring and has a structure linked to the pyrazine ring. The above pyrazine ring may or may not be substituted by any functional group. The above benzene ring may or may not be substituted by any functional group.

[0051] Preferably, the above heterocyclic compound is a compound in which at least four oxygen atoms are bonded to the above benzene ring. Thereby, the above heterocyclic compound can accumulate more charges even with a small molecular weight. As a result, by using the above heterocyclic compound as the positive electrode active material, a power storage cell with a large energy density per unit mass of the power storage cell can be obtained.

[0052] Preferably, the above heterocyclic compound is a compound in which an even number of oxygen atoms of 4 or more are bonded to the above benzene ring. The above heterocyclic compound may be a compound in which an even number of oxygen atoms of 4 or more and 12 or less are bonded to the above benzene ring. Thereby, the chemical stability of the heterocyclic compound is improved.

[0053] The positive electrode active material layer 224 may contain phenazines as the positive electrode active material. Preferably, the above phenazines are compounds in which at least four oxygen atoms are bonded to the benzene ring contained in the phenazine structure. As described above, thereby, a power storage cell with a large energy density per unit mass of the power storage cell can be obtained.

[0054] The above-mentioned phenazines are preferably compounds in which an even number of oxygen atoms of 4 or more are bonded to the above-mentioned benzene ring. The above-mentioned phenazines may be compounds in which an even number of oxygen atoms of 4 or more and 8 or less are bonded to the above-mentioned benzene ring. Thereby, the chemical stability of the heterocyclic compound is improved.

[0055] The above-mentioned positive electrode active material is composed of, for example, a heterocyclic compound containing one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof. The above-mentioned positive electrode active material mainly contains, for example, a heterocyclic compound containing one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof.

[0056] The above-mentioned heterocyclic compound or its salt or derivative, and phenazines are included in, for example, any of the reaction starting materials, products, and intermediate products in at least the discharge reaction of the battery electrode reaction. Details of the heterocyclic compound or its salt or derivative, and phenazines that can be used as the positive electrode active material will be described later.

[0057] The positive electrode active material is not limited to the above-mentioned heterocyclic compound. When the power storage cell 112 is a lithium ion secondary battery or a lithium metal secondary battery, other examples of the positive electrode active material include LiMnO2, LiNiO2, LiCoO2, Li(Mn x Ni 1-x )O2, Li(Mn x Co 1-x )O2, Li(Ni y Co 1-y )O2, Li(Mn x Ni y Co 1-x-y )O2 and other layered oxides; solid solutions such as Li2MnO3-LiNiO2, Li2MnO3-LiCoO2, Li2MnO3-Li(Ni y Co 1-y )O2; Li2MnSiO4, Li2NiSiO4, Li2CoSiO4, Li2(Mn x Ni 1-x )SiO4, Li2(Mn x Co 1-x )SiO4, Li2(Ni yCo 1-y )SiO4, Li2(Mn x Ni y Co 1-x-y )SiO4 and other silicates; LiMnBO3, LiNiBO3, LiCoBO3, Li(Mn x Ni 1-x )BO3, Li(Mn x Co 1-x )BO3, Li(Ni y Co 1-y )BO3, Li(Mn x Ni y Co 1-x-y )BO3 and other borates; V2O5; LiV3O6; MnO and the like. In the above formula, 0 < x < 1, 0 < y < 1, and 0 < x + y < 1. These cathode active materials may be used alone or two or more cathode active materials may be combined.

[0058] When the power storage cell 112 is a sodium-ion secondary battery, other examples of the cathode active material include NaFeO2, NaNiO2, NaCoO2, NaMnO2, NaVO2, Na(Ni X Mn 1-X )O2, Na(Fe X Mn 1-X )O2, NaVPO4F, Na2FePO4F, Na3V2(PO4)3 and the like. In the above formula, 0 < x < 1. These cathode active materials may be used alone or two or more cathode active materials may be combined.

[0059] In the present embodiment, the binder binds the materials constituting the cathode active material layer 224 (for example, the cathode active material, the conductive assistant, etc.) and maintains the electrode shape of the cathode 220. The type of the binder is not particularly limited, and examples of the binder include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, and the like.

[0060] In this embodiment, the conductive additive reduces the resistance of the positive electrode 220. The type of the conductive additive is not particularly limited as long as it has a desired electron conductivity, and examples of the conductive additive include carbon materials. Examples of the carbon material include graphite, carbon black (for example, acetylene black, ketjen black, etc.), coke, amorphous carbon, carbon fiber, carbon nanotube, graphene, and the like. These conductive additives may be used alone, or two or more conductive additives may be combined.

[0061] When the positive electrode active material layer 224 does not contain a conductive additive, the content of the positive electrode active material in the positive electrode active material layer 224 is preferably 40 to 99% by mass, more preferably 70 to 97% by mass, and even more preferably 80 to 95% by mass. The content of the binder in the positive electrode active material layer 224 is preferably 1 to 60% by mass, more preferably 3 to 30% by mass, and even more preferably 5 to 20% by mass.

[0062] When the positive electrode active material layer 224 contains a conductive additive, the content of the conductive additive in the positive electrode active material layer 224 is preferably 0.2 to 20% by mass, more preferably 1 to 10% by mass, and even more preferably 2 to 6% by mass. At this time, the content of the positive electrode active material in the positive electrode active material layer 224 is preferably 60 to 98% by mass, more preferably 70 to 96% by mass, and even more preferably 80 to 94% by mass. Also, the content of the binder in the positive electrode active material layer 224 is preferably 1.8 to 39.8% by mass, more preferably 3 to 29% by mass, and even more preferably 4 to 18% by mass.

[0063] Note that the content of the binder in the positive electrode active material layer 224 may be 1 to 20% by mass, may be 2 to 10% by mass, or may be 3 to 6% by mass. In this case, the balance of the positive electrode active material layer 224 may be a positive electrode active material, or may be a mixture of a positive electrode active material and a conductive additive.

[0064] [Separator] In this embodiment, the separator 230 separates the positive electrode 220 and the negative electrode 240. The separator 230 ensures the ionic conductivity between the positive electrode 220 and the negative electrode 240, for example, by holding an electrolytic solution. Examples of the material of the separator 230 include polyethylene, polypropylene, ethylene-propylene copolymer, glass, or a composite thereof. Examples of the shape of the separator 230 include a microporous film, a non-woven fabric, a filter, etc. The thickness of the separator 230 is not particularly limited, but is preferably 10 to 50 μm. The aperture ratio of the separator 230 is not particularly limited, but is preferably 30 to 70%.

[0065] [Negative electrode] In this embodiment, the negative electrode current collector 242 holds the negative electrode active material layer 244. Examples of the material of the negative electrode current collector 242 include copper, aluminum, stainless steel, nickel, titanium, or an alloy thereof. The negative electrode current collector 242 may include a resin support layer and a metal layer disposed on the surface of the support layer. Examples of the above resin include polyethylene, polypropylene, polyethylene terephthalate, polyimide, etc. The above metal layer may be a layer made of copper, aluminum, stainless steel, nickel, titanium, or an alloy thereof. The above metal layer may include a layer made of copper, aluminum, stainless steel, nickel, titanium, or an alloy thereof. The metal layer may be a foil or a plated layer.

[0066] When lithium metal is used as the negative electrode active material, the lithium metal can also serve as the current collector. Therefore, when the power storage cell 112 is a lithium metal secondary battery, the power storage cell 112 may not include the negative electrode current collector 242.

[0067] Examples of the shape of the negative electrode current collector 242 include a foil, a mesh, a punched metal, an expanded metal, etc. The thickness of the negative electrode current collector 242 is not particularly limited, but may be 5 to 200 μm. The thickness of the negative electrode current collector 242 is preferably 6 to 20 μm.

[0068] In this embodiment, the negative electrode active material layer 244 is formed on at least one surface of the negative electrode current collector 242. The thickness of the negative electrode active material layer 244 may be 1 to 300 μm, or 2 to 200 μm per one side of the negative electrode current collector 242. The negative electrode active material layer 244 contains, for example, a negative electrode active material and a binder. The negative electrode active material layer 244 may contain a conductive auxiliary agent.

[0069] In one embodiment, the negative electrode active material layer 244 is formed by applying a paste containing a material constituting the negative electrode active material layer 244 and an organic solvent onto at least one surface of the negative electrode current collector 242 and drying the paste. The type of the above organic solvent is not particularly limited, and examples of the above organic solvent include N-methylpyrrolidone (NMP). In other embodiments, the negative electrode active material layer 244 is formed by mixing the materials constituting the negative electrode active material layer 244 and molding them into a sheet shape, and pressing the sheet-shaped mixture onto at least one surface of the negative electrode current collector 242.

[0070] The negative electrode active material layer 244 may contain, as the negative electrode active material, a heterocyclic compound containing one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof. The above heterocyclic compound may be a compound containing a phenazine structure. The phenazine structure has (i) one pyrazine ring and two benzene rings, and (ii) each of the two benzene rings shares one carbon-carbon bond of the pyrazine ring with the pyrazine ring and is linked to the pyrazine ring. The above pyrazine ring may or may not be substituted with an arbitrary functional group. The above benzene ring may or may not be substituted with an arbitrary functional group.

[0071] Similar to the heterocyclic compound described in relation to the positive electrode active material layer 224, the heterocyclic compound that can be used for the negative electrode active material layer 244 is preferably a compound in which at least 4 oxygen atoms are bonded to the benzene ring described above. The above heterocyclic compound is preferably a compound in which an even number of oxygen atoms of 4 or more are bonded to the benzene ring described above. The above heterocyclic compound may be a compound in which an even number of oxygen atoms of 4 or more and 12 or less are bonded to the benzene ring described above.

[0072] The negative electrode active material layer 244 may contain phenazines as the negative electrode active material. The above phenazines are preferably compounds in which at least 4 oxygen atoms are bonded to the benzene ring contained in the phenazine structure. The above phenazines are preferably compounds in which an even number of oxygen atoms of 4 or more are bonded to the benzene ring described above. The above phenazines may be compounds in which an even number of oxygen atoms of 4 or more and 8 or less are bonded to the benzene ring described above.

[0073] The above negative electrode active material consists of, for example, a heterocyclic compound containing 1 or more pyrazine rings and 2 or more benzene rings, or a salt or derivative thereof. The above negative electrode active material mainly contains, for example, a heterocyclic compound containing 1 or more pyrazine rings and 2 or more benzene rings, or a salt or derivative thereof.

[0074] The above heterocyclic compound or its salt or derivative, and phenazines are included in, for example, any of the reaction starting materials, products, and intermediate products in at least the charging reaction of the battery electrode reaction. Details of the heterocyclic compound or its salt or derivative, and phenazines that can be used as the negative electrode active material will be described later.

[0075] The negative electrode active material is not limited to the above heterocyclic compounds and the like. When the power storage cell 112 is a lithium ion secondary battery, other examples of the negative electrode active material include (i) graphite, (ii) poorly sinterable carbon or poorly graphitizable carbon, (iii) tin, silicon, and alloys containing these, and (iv) SiO and the like. When materials such as (i) graphite, (ii) poorly sinterable carbon or poorly graphitizable carbon, (iii) tin, silicon, and alloys containing these, and (iv) SiO are used as the negative electrode active material, the material may be pre-doped with lithium.

[0076] The negative electrode active material may be a lithium-containing substance such as metallic lithium or a lithium alloy. For example, when the power storage cell 112 is a lithium metal secondary battery, metallic lithium is used as the negative electrode. These negative electrode active materials may be used alone, or two or more negative electrode active materials may be combined.

[0077] The negative electrode active material layer 244 may include a lithium metal foil. Thereby, lithium is supplied to the power storage cell 112. The thickness of the lithium metal foil may be 1 to 300 μm, may be 2 to 200 μm, or may be 3 to 100 μm. The thickness and / or mass of the lithium metal foil may be determined according to the content of the positive electrode active material in the positive electrode active material layer 224.

[0078] When the power storage cell 112 is a sodium ion secondary battery, other examples of the negative electrode active material include (i) graphite, (ii) poorly sinterable carbon or poorly graphitizable carbon, (iii) tin, silicon, and alloys containing these, and (iv) titanium oxide and the like. The negative electrode active material may be a sodium-containing substance such as metallic sodium or a sodium alloy. These negative electrode active materials may be used alone, or two or more negative electrode active materials may be combined.

[0079] In this embodiment, the binder binds the materials (such as positive electrode active materials, conductive aids, etc.) that constitute the negative electrode active material layer 244 and maintains the electrode shape of the negative electrode 240. The type of the binder is not particularly limited, and examples of the binder include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, and the like.

[0080] In this embodiment, the conductive aid reduces the resistance of the negative electrode 240. The type of the conductive aid is not particularly limited as long as it has a desired electron conductivity, and examples of the conductive aid include carbon materials. Examples of the carbon materials include graphite, carbon black (such as acetylene black, ketjen black, etc.), coke, amorphous carbon, carbon fiber, carbon nanotube, graphene, and the like. These conductive aids may be used alone, or two or more kinds of conductive aids may be combined.

[0081] When the negative electrode active material layer 244 does not contain a conductive aid, the content of the negative electrode active material in the negative electrode active material layer 244 is preferably 40 to 99% by mass, more preferably 80 to 98.5% by mass, and even more preferably 90 to 98% by mass. The content of the binder in the negative electrode active material layer 244 is preferably 1 to 60% by mass, more preferably 1.5 to 20% by mass, and even more preferably 2 to 10% by mass.

[0082] When the negative electrode active material layer 244 contains a conductive aid, the content of the conductive aid in the negative electrode active material layer 244 is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, and even more preferably 2 to 5% by mass. At this time, the content of the negative electrode active material in the negative electrode active material layer 244 is preferably 40 to 98% by mass, more preferably 80 to 97% by mass, and even more preferably 90 to 96% by mass. Also, the content of the binder in the negative electrode active material layer 244 is preferably 1.9 to 59.9% by mass, more preferably 2 to 19% by mass, and even more preferably 2 to 8% by mass.

[0083] Note that the content of the binder in the negative electrode active material layer 244 may be 0.1 to 5% by mass, may be 0.2 to 3% by mass, or may be 0.5 to 1% by mass. In this case, the balance of the negative electrode active material layer 244 may be a negative electrode active material or a mixture of a negative electrode active material and a conductive assistant.

[0084] [Electrolyte] In the present embodiment, the electrolytic solution 250 realizes ionic conduction between the positive electrode active material and the negative electrode active material through the electrolyte contained in the electrolytic solution 250. According to the present embodiment, a non-aqueous electrolytic solution is used as the electrolytic solution 250. As the non-aqueous electrolytic solution, a known organic electrolytic solution can be used. For example, when the power storage cell 112 is a lithium ion secondary battery or a lithium metal secondary battery, (i) a solution in which a lithium salt such as lithium perchlorate or LiPF6 is dissolved in a solvent composed of one or more of ethylene carbonate, dimethyl carbonate, diethyl carbonate, etc. is used as the electrolytic solution 250.

[0085] The non-aqueous electrolyte contains, for example, a metal salt and a non-aqueous solvent. Examples of the metal salt include sodium salts and lithium salts. Examples of the sodium salts include inorganic sodium salts such as NaPF6, NaBF4, NaClO4, and NaAsF6, and organic sodium salts such as NaCF3SO3, NaN(CF3SO2)2, NaN(C2F5SO2)2, and NaC(CF3SO2)3. Examples of the lithium salts include inorganic lithium salts such as LiPF6, LiBF4, LiClO4, and LiAsF6, and organic lithium salts such as LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, and LiC(CF3SO2)3. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), butylene carbonate (BC), fluoroethylene carbonate (FEC), γ-butyrolactone, sulfolane, acetonitrile, 1,2-dimethoxymethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, and mixtures thereof.

[0086] The concentration of the sodium salt in the non-aqueous electrolyte is not particularly limited, but may be in the range of 0.5 to 4.0 mol / L. The concentration of the sodium salt may be in the range of 0.7 mol / L to 2.0 mol / L, or may be in the range of 1.0 mol / L to 1.5 mol / L. The concentration of the lithium salt in the non-aqueous electrolyte is not particularly limited, but may be in the range of 0.5 to 4.0 mol / L. The concentration of the lithium salt may be in the range of 0.7 mol / L to 2.0 mol / L, or may be in the range of 1.0 mol / L to 1.5 mol / L.

[0087] [An example of another embodiment] In the present embodiment, the details of the power storage cell 112 have been described by taking the case where the power storage cell 112 is a coin-type secondary battery as an example. However, the type, structure, etc. of the power storage cell 112 are not limited to the present embodiment. In other embodiments, the power storage cell 112 may be a cylindrical battery including a wound electrode body in which a positive electrode, a separator, and a negative electrode are wound in a spiral shape. Further, in still other embodiments, the power storage cell 112 may be a laminate-type battery in which a laminate electrode body in which a positive electrode and a negative electrode are alternately laminated with a separator interposed therebetween is sealed with a laminate.

[0088] In the present embodiment, the details of the power storage cell 112 have been described by taking the case where the negative electrode 240 has a negative electrode current collector 242 and a negative electrode active material layer 244 as an example. However, the negative electrode of the power storage cell 112 is not limited to the present embodiment. In other embodiments, for example, when the power storage cell 112 is a lithium metal secondary battery, metallic lithium can be used as the negative electrode.

[0089] In the present embodiment, an example of the power storage cell 112 has been described by taking the case where the electrolytic solution 250 is used as the electrolyte of the power storage cell 112 as an example. However, the electrolyte of the power storage cell 112 is not limited to the present embodiment. In other embodiments, a solid electrolyte or a gel electrolyte may be used as the electrolyte of the power storage cell 112. Examples of the solid electrolyte include inorganic solid electrolytes such as Li2S-P2S5-based and Li2S-GeS2-P2S5-based.

[0090] As described above, the details of the aircraft 100 and the power storage cell 112 have been described with reference to FIGS. 1 and 2. Next, the details of the heterocyclic compound or its salt or derivative used as the positive electrode active material or the negative electrode active material, and phenazines will be described.

[0091] [I. Active Material] As described above, according to the present embodiment, as a positive electrode active material or a negative electrode active material for a secondary battery (which may be simply referred to as an active material), a heterocyclic compound containing one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof is used. The above heterocyclic compound may be a compound containing a phenazine structure. The above heterocyclic compound is preferably a compound in which at least four oxygen atoms are bonded to the above benzene ring. The above heterocyclic compound may be a compound in which an even number of oxygen atoms of 4 or more are bonded to the above benzene ring.

[0092] As an active material for a secondary battery, phenazine or a salt or derivative thereof (which may be referred to as phenazines) may be used. The above phenazines are preferably compounds in which at least four oxygen atoms are bonded to the benzene ring contained in the phenazine structure. The above phenazines may be compounds in which an even number of oxygen atoms of 4 or more are bonded to the above benzene ring.

[0093] [First Embodiment] In one embodiment, the above active material includes a compound represented by the following general formula (1), general formula (2), general formula (3), general formula (4), general formula (4), general formula (5), general formula (6) or general formula (7), or a salt thereof. The above compound or its salt may be included in any of the reaction starting materials, products, and intermediate products in the discharge reaction of the battery electrode reaction. The above compound or its salt may be included in any of the reaction starting materials, products, and intermediate products in the charge reaction of the battery electrode reaction.

[0094] [General Formula (1)] [Chemical Formula]

[0095] In General Formula (1), R 101 ~R 108Each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent Rs 101 ~R 108 are connected to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent single bonds or double bonds.

[0096] In this embodiment, at least four of R 101 ~R 108 are an oxygen atom or a group represented by -OM (which may be referred to as an OM group). The number of oxygen atoms or OM groups among R 101 ~R 108 may be an even number of 4 or more. All of R 101 ~R 108 may be an oxygen atom or an OM group.

[0097] As a result, the number of electrons involved in the redox reaction increases. Specifically, a multi-electron reaction of 4 or more electrons becomes possible in the redox reaction, and the theoretical capacity of the active material increases. Therefore, the active material can accumulate more charges even with a small molecular weight. As a result, a power storage cell with a large energy density per unit mass of the power storage cell can be obtained.

[0098] In the state where the active material is fully charged, (i) all of the above oxygen atoms or OM groups become oxygen atoms, and (ii) the bond between the oxygen atom and the carbon of the benzene ring contained in the phenazine structure becomes a double bond. At this time, no atom represented by the above-mentioned M is bonded to the nitrogen atom contained in the pyrazine ring of the phenazine structure. For example, no hydrogen ion or metal ion is bonded to the above nitrogen atom.

[0099] On the one hand, in a state where the active material is completely discharged, (i) all of the above oxygen atoms or OM groups become OM groups, and (ii) the bond between the oxygen atom of the OM group and the carbon of the benzene ring contained in the phenazine structure becomes a single bond. At this time, an atom represented by M described above is bonded to the nitrogen atom contained in the pyrazine ring of the phenazine structure. For example, a hydrogen ion or a metal ion is bonded to the above nitrogen atom.

[0100] R 101 ~R 108 The organic group represented by may be a substituted or unsubstituted hydrocarbon group. The above hydrocarbon group may be a monovalent hydrocarbon group. R 101 ~R 108 The organic groups represented by may be such that two adjacent organic groups are linked to each other to form a ring.

[0101] Examples of the above organic groups include substituted or unsubstituted alkyl groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted alkynyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted carboxy groups, substituted or unsubstituted alkoxycarbonyl groups, substituted or unsubstituted acyl groups, substituted or unsubstituted acyloxy groups, substituted or unsubstituted aryl groups, substituted or unsubstituted aryloxy groups, substituted or unsubstituted heteroaryl groups, substituted or unsubstituted heteroaryloxy groups, substituted or unsubstituted ester groups, substituted or unsubstituted ether groups, substituted or unsubstituted amino groups, substituted or unsubstituted sulfonic acid groups, substituted or unsubstituted cyano groups, substituted or unsubstituted thioether groups, and the like. The above organic group may be a monovalent group having an ester bond (-COO-), or may be a monovalent group having an ether bond (-O-). The above organic group may contain boron. The above organic group may contain boron as a heteroatom.

[0102] The above organic group may be composed of one or more atoms selected from the group consisting of carbon, hydrogen, oxygen, nitrogen, and boron. These atoms have a smaller atomic weight compared to, for example, sulfur. Therefore, when the above organic group is composed of carbon, hydrogen, oxygen, nitrogen, and boron, the molecular weight of the compound used as the active material becomes relatively small. As a result, the mass energy density of the active material or the energy storage cell is improved. The above organic group may also be composed of one or more atoms selected from the group consisting of carbon, hydrogen, oxygen, and nitrogen.

[0103] When the number of electrons involved in the redox reaction in the active material is the same, as the molecular weight of the active material increases, the amount of charge that can be accumulated per unit mass decreases. Therefore, when the above organic group is a substituted or unsubstituted hydrocarbon group, the number of carbon atoms in the organic group is preferably 1 to 6, more preferably less than 4, and even more preferably 2 or less. The number of carbon atoms in the above organic group may be 1.

[0104] Examples of the above organic group include substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, substituted or unsubstituted aryl groups, substituted or unsubstituted carboxy groups, and the like. In the above active material, the smaller the molecular weight and / or size of the organic group, the more the decrease in the capacity of the energy storage cell can be suppressed. Alkyl groups, alkoxy groups, aryl groups, and carboxy groups have relatively small molecular weights or sizes. Therefore, when the above active material contains these groups, the decrease in the capacity of the energy storage cell containing the above active material can be suppressed compared to the case where the above active material contains other organic groups.

[0105] Examples of the above alkyl group include alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, and tert-butyl group. The number of carbon atoms in the alkyl group is particularly preferably 1 to 3. The above alkyl group may be a linear alkyl group or a branched alkyl group.

[0106] Examples of the above alkoxy group include alkoxy groups having 1 to 6 carbon atoms such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butyloxy group, isobutyloxy group, sec-butyloxy group, and tert-butyloxy group. The number of carbon atoms of the alkoxy group is particularly preferably 1 to 3. The above alkoxy group may be a linear alkoxy group or a branched alkoxy group.

[0107] Examples of the above aryl group include phenyl group, naphthyl group, anthranyl group, phenanthryl group, biphenyl group, and pyridyl group. The aryl group is particularly preferably a phenyl group.

[0108] R 101 ~R 108 In the OM group represented by R

[0109] ~R 101 ~R 108 M may be H, Li, Na, K, Mg or Ca. The type of metal atom represented by M may be the same as the type of metal atom constituting the metal ion that moves between the positive electrode and the negative electrode of the secondary battery. For example, when the secondary battery is a lithium ion secondary battery or a lithium metal secondary battery, M represents a hydrogen atom or a lithium atom. When the secondary battery is a sodium ion battery, M represents a hydrogen atom or a sodium atom.

[0110] In this embodiment, it is preferable that the compound represented by the general formula (1) has symmetry. For example, the compound represented by the general formula (1) has a symmetry axis, a symmetry plane, or a center of symmetry.

[0111] According to the general formula (1), the fully oxidized form and the fully reduced form of a specific compound are represented. When both the above-mentioned fully oxidized form and fully reduced form are not radical forms, a reversible oxidation-reduction reaction can be obtained. When the compound represented by the general formula (1) has symmetry, since both the fully oxidized form and the fully reduced form of the compound are not radical forms, a reversible oxidation-reduction reaction can be obtained. Also, considering the ease of synthesis, it is preferable that among R 101 ~R 108 those other than an oxygen atom or an OM group are the same.

[0112] [General formula (2)] [Chemical formula]

[0113] In the general formula (2), R 201 ~R 210 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 201 ~R 210 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid lines and broken lines represent a single bond or a double bond.

[0114] In this embodiment, at least four of R 201 ~R 210 are an oxygen atom or an OM group. The number of oxygen atoms or OM groups among R 201 ~R 210 may be an even number of 4 or more. All of R 201 ~R 210 may be an oxygen atom or an OM group.

[0115] R 201 ~R 210Each of them is the above-mentioned R 101 ~R 108 may have the same configuration as each of them. For example, R 201 ~R 210 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. Also, each of R 201 ~R 210 can be determined so that the compound represented by the general formula (2) has symmetry. Each of R 201 ~R 210 can be determined so that the compound represented by the general formula (2) has a symmetry axis, a symmetry plane or a center of symmetry.

[0116] [General formula (3)] [Chemical formula]

[0117] In the general formula (3), R 301 ~R 310 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 301 ~R 310 are connected to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond.

[0118] In this embodiment, at least 4 of R 301 ~R 310 are an oxygen atom or an OM group. The number of oxygen atoms or OM groups among R 301 ~R 310 may be an even number of 4 or more. All of R 301 ~R 310 may be an oxygen atom or an OM group.

[0119] R 301 ~R 310 each may have the same configuration as each of the above-mentioned R 101 ~R 108 For example, R301 ~R 310 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. Also, R 301 ~R 310 each of them can be determined such that the compound represented by the general formula (3) has symmetry. R 301 ~R 310 each of them may be determined such that the compound represented by the general formula (3) has a symmetry axis, a symmetry plane, or a center of symmetry.

[0120] [General formula (4)] [Chemical formula]

[0121] In the general formula (4), R 401 ~R 410 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 401 ~R 410 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond.

[0122] In this embodiment, at least four of R 401 ~R 410 are an oxygen atom or an OM group. The number of oxygen atoms or OM groups among R 401 ~R 410 may be an even number of 4 or more. All of R 401 ~R 410 may be an oxygen atom or an OM group.

[0123] R 401 ~R 410 each may have the same configuration as each of the above-described R 101 ~R 108 For example, R 401 ~R 410each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. Also, R 401 ~R 410 each can be determined such that the compound represented by the general formula (4) has symmetry. R 401 ~R 410 each may be determined such that the compound represented by the general formula (4) has a symmetry axis, a symmetry plane, or a center of symmetry.

[0124] [General formula (5)] [Chemical formula]

[0125] In the general formula (5), R 501 ~R 512 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 501 ~R 512 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond.

[0126] In this embodiment, at least four of R 501 ~R 512 are an oxygen atom or an OM group. The number of oxygen atoms or OM groups among R 501 ~R 512 may be an even number of 4 or more. All of R 501 ~R 512 may be an oxygen atom or an OM group.

[0127] R 501 ~R 512 each may have the same configuration as each of the above-described R 101 ~R 108 For example, R 501 ~R 512 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. Also, R 501 ~R512 Each of them can be determined such that the compound represented by the general formula (5) has symmetry. R 501 ~R 512 Each of them may be determined such that the compound represented by the general formula (5) has a symmetry axis, a symmetry plane, or a center of symmetry.

[0128] [General formula (6)] [Chemical formula]

[0129] In the general formula (6), R 601 ~R 612 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 601 ~R 612 are connected to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond.

[0130] In this embodiment, at least four of R 601 ~R 612 are an oxygen atom or an OM group. The number of oxygen atoms or OM groups among R 601 ~R 612 may be an even number of 4 or more. All of R 601 ~R 612 may be an oxygen atom or an OM group.

[0131] R 601 ~R 612 Each of them may have the same configuration as each of the above-described R 101 ~R 108 . For example, R 601 ~R 612 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. Also, each of R 601 ~R 612 may be determined such that the compound represented by the general formula (6) has symmetry. R 601 ~R612 Each of them may be determined such that the compound represented by the general formula (6) has a symmetry axis, a symmetry plane, or a center of symmetry.

[0132] [General formula (7)] [Chemical formula]

[0133] In general formula (7), R 701 ~R 712 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 701 ~R 712 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond.

[0134] In this embodiment, at least four of R 701 ~R 712 are an oxygen atom or an OM group. The number of oxygen atoms or OM groups among R 701 ~R 712 may be an even number of 4 or more. All of R 701 ~R 712 may be an oxygen atom or an OM group.

[0135] Each of R 701 ~R 712 may have the same configuration as each of the above-described R 101 ~R 108 . For example, each of R 701 ~R 712 independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. Also, each of R 701 ~R 712 may be determined such that the compound represented by the general formula (7) has symmetry. Each of R 701 ~R 712 may be determined such that the compound represented by the general formula (7) has a symmetry axis, a symmetry plane, or a center of symmetry.

[0136] [Specific examples of compounds used as active materials] In one embodiment, the following compounds are exemplified as specific examples of the above active materials. In the following compounds, R 1 , R 2 , R 3 and R 4 each independently represent a hydrogen atom or an organic group. The organic group represented by R 1 ~R 4 may have the same configuration as the organic group represented by the above-mentioned R 101 ~R 108 .

[0137] The following compounds correspond to the state where the active material is fully charged. The following compounds may be an example of the fully oxidized form of the compound represented by general formula (1), general formula (2), general formula (3), general formula (4), general formula (4), general formula (5), general formula (6) or general formula (7). It should be noted that the following compounds are conjugated molecules and have resonance structures. The compounds represented by general formula (1), general formula (2), general formula (3), general formula (4), general formula (4), general formula (5), general formula (6) or general formula (7) are not limited thereto. As other specific examples, the fully reduced form or partially reduced form of the following compounds may be exemplified.

[0138] [An example of the fully oxidized form] [Chemical formula]

[0139] In other embodiments, the following compounds are exemplified as specific examples of the above active materials. In the following compounds, R 5 , R 6 , R 7 and R 8 each independently represent a hydrogen atom or an organic group. The organic group represented by R 5 ~R 8 may have the same configuration as the organic group represented by the above-mentioned R 101 ~R 108 .

[0140] The following compound corresponds to the state where the active material is completely discharged. The following compound may be an example of a fully reduced form of a compound represented by general formula (1), general formula (2), general formula (3), general formula (4), general formula (4), general formula (5), general formula (6) or general formula (7). The following compound may be a fully reduced form of the above compound exemplified as a compound corresponding to the state where the active material is completely charged. Note that the following compound is a conjugated molecule and has a resonance structure.

[0141] [Example of fully reduced form] [Chemical formula]

[0142] In the above, as an example, the case where M in general formulas (1) to (7) is Li is taken, and a compound corresponding to the state where the active material is completely discharged is exemplified. However, the above M is not limited to Li. As described above, M may be a hydrogen atom, or a monovalent or divalent metal atom.

[0143] As is clear from the specific examples of the fully oxidized form and the fully reduced form of the above compound, in the fully reduced form or the partially reduced form, the C=O of the 6-membered carbon ring in the fully oxidized form becomes C-OM, and the =N- of the pyrazine ring in the fully oxidized form becomes -NM-, which is different from the fully oxidized form. Also, the fully reduced form or the partially reduced form is different from the fully oxidized form in that the 6-membered carbon ring becomes an aromatic ring and the nitrogen-containing 6-membered ring has the structure shown in the above chemical formula. The bond between OM in the above C-OM may be an ionic bond. The bond between NM in the above NM may be an ionic bond.

[0144] [Specific example of the compound represented by general formula (1)] The compound represented by general formula (1) has a small ratio of the molecular weight of the compound to the number of electrons involved in the redox reaction in the compound. Also, in the compound represented by general formula (1), R 101 ~R 108When something other than an oxygen atom or an OM group is a hydrogen atom among them, the ratio of the molecular weight of the compound to the number of electrons involved in the redox reaction in the compound becomes smaller.

[0145] Hereinafter, R 101 ~R 108 Among them, 4 are oxygen atoms or OM groups, and when something other than an oxygen atom or an OM group among R 101 ~R 108 is a hydrogen atom, specific examples of the fully oxidized form of the compound represented by the general formula (1) are disclosed. However, the compound represented by the general formula (1) is not limited to these. As other specific examples, fully reduced forms or partially reduced forms of the following compounds may be exemplified. Also, note that the following compounds are conjugated molecules and have resonance structures.

[0146] [Specific examples of fully oxidized forms] [Chemical formula]

[0147] Hereinafter, R 101 ~R 108 Among them, 6 are oxygen atoms or OM groups, and when something other than an oxygen atom or an OM group among R 101 ~R 108 is a hydrogen atom, specific examples of the fully oxidized form of the compound represented by the general formula (1) are disclosed. However, the compound represented by the general formula (1) is not limited to these. As other specific examples, fully reduced forms or partially reduced forms of the following compounds may be exemplified. Also, note that the following compounds are conjugated molecules and have resonance structures.

[0148] [Specific examples of fully oxidized forms] [Chemical formula]

[0149] Hereinafter, R 101 ~R 108Taking the case where all of them are oxygen atoms or OM groups as an example, specific examples of the fully oxidized form of the compound represented by the general formula (1) are disclosed. However, the compound represented by the general formula (1) is not limited to these. As other specific examples, the fully reduced form or partially reduced form of the following compounds may be exemplified. Also, it should be noted that the following compounds are conjugated molecules and have resonance structures.

[0150] [Specific examples of the fully oxidized form] [Chemical formula]

[0151] [Specific examples of the compound represented by the general formula (2)] For the compound represented by the general formula (2), the ratio of the molecular weight of the compound to the number of electrons involved in the oxidation-reduction reaction in the compound is small. Also, in the compound represented by the general formula (2), when among R 201 ~R 210 those other than oxygen atoms or OM groups are hydrogen atoms, the ratio of the molecular weight of the compound to the number of electrons involved in the oxidation-reduction reaction in the compound becomes smaller.

[0152] Hereinafter, taking the case where 4 of R 201 ~R 210 are oxygen atoms or OM groups and those other than oxygen atoms or OM groups among R 201 ~R 210 are hydrogen atoms as an example, specific examples of the fully oxidized form of the compound represented by the general formula (2) are disclosed. However, the compound represented by the general formula (2) is not limited to these. As other specific examples, the fully reduced form or partially reduced form of the following compounds may be exemplified. Also, it should be noted that the following compounds are conjugated molecules and have resonance structures.

[0153] [Specific examples of the fully oxidized form] [Chemical formula]

[0154] Among the following, six of R 201 ~R 210 are oxygen atoms or OM groups, and taking the case where those other than oxygen atoms or OM groups among R 201 ~R 210 are hydrogen atoms as an example, specific examples of the fully oxidized form of the compound represented by the general formula (2) are disclosed. However, the compound represented by the general formula (2) is not limited to these. As other specific examples, fully reduced forms or partially reduced forms of the following compounds may be exemplified. Also, note that the following compounds are conjugated molecules and have resonance structures.

[0155]

Chemical formula

[0156] Among the following, eight of R 201 ~R 210 are oxygen atoms or OM groups, and taking the case where those other than oxygen atoms or OM groups among R 201 ~R 210 are hydrogen atoms as an example, specific examples of the fully oxidized form of the compound represented by the general formula (2) are disclosed. However, the compound represented by the general formula (2) is not limited to these. As other specific examples, fully reduced forms or partially reduced forms of the following compounds may be exemplified. Also, note that the following compounds are conjugated molecules and have resonance structures.

[0157] [Specific examples of fully oxidized form]

Chemical formula

[0158] Among the following, taking the case where ten of R 201 ~R 210 are oxygen atoms or OM groups as an example, specific examples of the fully oxidized form of the compound represented by the general formula (2) are disclosed. Also, R 301 ~R 310Taking the case where 10 of them are oxygen atoms or OM groups as an example, specific examples of the fully oxidized form of the compound represented by the general formula (3) are disclosed. However, the compounds represented by the general formula (2) or the general formula (3) are not limited thereto. As other specific examples, fully reduced forms or partially reduced forms of the following compounds may be exemplified. Also, it should be noted that the following compounds are conjugated molecules and have resonance structures.

[0159] [Specific examples of fully oxidized form] [Chemical formula]

[0160] Below, when 6 of R 301 ~R 310 are oxygen atoms or OM groups, and those other than oxygen atoms or OM groups among R 301 ~R 310 are hydrogen atoms, specific examples of the fully oxidized form of the compound represented by the general formula (3) are disclosed. However, the compounds represented by the general formula (3) are not limited thereto. As other specific examples, fully reduced forms or partially reduced forms of the following compounds may be exemplified. Also, it should be noted that the following compounds are conjugated molecules and have resonance structures.

[0161] [Specific examples of fully oxidized form] [Chemical formula]

[0162] Below, when 8 of R 301 ~R 310 are oxygen atoms or OM groups, and R 301 ~R 310Taking the case where those other than the oxygen atom or the OM group are hydrogen atoms as an example, specific examples of the fully oxidized form of the compound represented by the general formula (3) are disclosed. However, the compound represented by the general formula (3) is not limited to these. As other specific examples, the fully reduced form or partially reduced form of the following compounds may be exemplified. Also, it should be noted that the following compounds are conjugated molecules and have resonance structures.

[0163] [Specific examples of the fully oxidized form] [Chemical formula]

[0164] [Specific examples of compounds having a center of symmetry] As described above, the above active material preferably includes compounds having a small molecular weight and symmetry among the compounds represented by the general formulas (1) to (7). The above active material may be a compound represented by the following chemical formula (1A-1) or chemical formula (1B-1). In the chemical formula (1B-1), M represents a hydrogen atom or a monovalent metal atom. M may be H, Li, Na, or K.

[0165] [Chemical formula (1A-1)] [Chemical formula]

[0166] [Chemical formula (1B-1)] [Chemical formula]

[0167] The chemical formula (1A-1) corresponds to the state where the active material is fully charged. The chemical formula (1B-1) corresponds to the state where the active material is fully discharged. For example, when the storage cell 112 is a lithium-ion secondary battery or a lithium metal secondary battery, the battery electrode reaction is represented by the following reaction formula 1.

[0168] [Reaction formula 1] [Chemistry]

[0169] That is, when the active material is fully charged, all four oxygens bonded to the benzene ring contained in the phenazine structure become oxygen atoms, and a compound represented by chemical formula (1A-1) can be formed. Then, as the discharge of the active material proceeds, lithium atoms are inserted into some of the oxygen atoms. And when the active material is fully discharged, all four oxygens bonded to the benzene ring contained in the phenazine structure are all bonded to Li, and a compound represented by chemical formula (1B-1) can be formed.

[0170] In Reaction Formula 1, the number of mobile electrons is 6, and the theoretical capacity of the compound represented by chemical formula (1A-2) or chemical formula (1B-2) is 670 [mAh / g]. The above theoretical capacity [mAh / g] is calculated by 26800 ÷ molar mass [g / mol] × number of mobile electrons [pieces].

[0171] The above active material may be a compound represented by the following chemical formula (1A-2) or chemical formula (1B-2). In chemical formula (1B-2), M represents a hydrogen atom or a monovalent metal atom. M may be H, Li, Na, or K.

[0172] [Chemical formula (1A-2)] [Chemistry]

[0173] [Chemical formula (1B-2)] [Chemistry]

[0174] Chemical formula (1A-2) corresponds to the state where the active material is fully charged. Chemical formula (1B-2) corresponds to the state where the active material is fully discharged. For example, when the storage cell 112 is a lithium-ion secondary battery or a lithium metal secondary battery, the battery electrode reaction is represented by the following Reaction Formula 2.

[0175] [Reaction formula 2] [Chem.]

[0176] That is, in the state where the active material is fully charged, all six oxygens bonded to the benzene ring contained in the phenazine structure become oxygen atoms, and a compound represented by chemical formula (1A-2) can be formed. Then, as the discharge of the active material progresses, lithium atoms are inserted into a part of the oxygen atoms. And in the state where the active material is fully discharged, all six oxygens bonded to the benzene ring contained in the phenazine structure are bonded to Li, and a compound represented by chemical formula (1B-2) can be formed. In Reaction formula 2, the number of mobile electrons is 8, and the theoretical capacity of the compound represented by chemical formula (1A-2) or chemical formula (1B-2) is 777 [mAh / g].

[0177] The above active material may be a compound represented by the following chemical formula (1A-3) or chemical formula (1B-3). In chemical formula (1B-3), M represents a hydrogen atom or a monovalent metal atom. M may be H, Li, Na, or K.

[0178] [Chemical formula (1A-3)] [Chem.]

[0179] [Chemical formula (1B-3)] [Chem.]

[0180] Chemical formula (1A-3) corresponds to the state where the active material is fully charged. Chemical formula (1B-3) corresponds to the state where the active material is fully discharged.

[0181] The above active material may be a compound represented by the following chemical formula (1A-4) or chemical formula (1B-4). In chemical formula (1B-4), M represents a hydrogen atom or a monovalent metal atom. M may be H, Li, Na, or K.

[0182] [Chemical formula (1A-4)] [Chem.]

[0183] [Chemical formula (1B-4)] [Chem.]

[0184] Chemical formula (1A-4) corresponds to the state where the active material is fully charged. Chemical formula (1B-4) corresponds to the state where the active material is fully discharged. For example, when the storage cell 112 is a lithium-ion secondary battery or a lithium metal secondary battery, the battery electrode reaction is represented by the following reaction formula 3.

[0185] [Reaction formula 3] [Chem.]

[0186] That is, in the state where the active material is fully charged, all eight oxygens bonded to the benzene ring contained in the phenazine structure become oxygen atoms, and a compound represented by chemical formula (1A-3) can be formed. Then, as the discharge of the active material proceeds, lithium atoms are inserted into a part of the oxygen atoms. And in the state where the active material is fully discharged, all eight oxygens bonded to the benzene ring contained in the phenazine structure are bonded to Li, and a compound represented by chemical formula (1B-3) can be formed. In reaction formula 3, the number of mobile electrons is 10, and the theoretical capacities of the compounds represented by chemical formula (1A-3) and chemical formula (1B-3) are 893 [mAh / g] and 726 [mAh / g], respectively.

[0187] As described above, the compounds represented by Chemical Formula (1A-1), Chemical Formula (1A-2), and Chemical Formula (1A-3) become, for example, groups represented by -OLi when a lithium atom is inserted into an oxygen atom. Therefore, these compounds can be used as a positive electrode active material. Among the compounds represented by General Formula (1) to General Formula (8), a group that binds to the benzene ring contained in the phenazine structure (for example, in the case of the compound represented by General Formula (1), the group represented by R 101 ~R 108 .) The same applies to compounds in which the oxygen atom is present.

[0188] Similarly, the compounds represented by Chemical Formula (1B-1), Chemical Formula (1B-2), and Chemical Formula (1B-3) become, for example, oxygen atoms when a lithium atom detaches from a group represented by -OLi. Therefore, these compounds can be used as a negative electrode active material. Among the compounds represented by General Formula (1) to General Formula (8), a group that binds to the benzene ring contained in the phenazine structure (for example, in the case of the compound represented by General Formula (1), the group represented by R 101 ~R 108 .) The same applies to compounds in which the OM group is present.

[0189] [Second Embodiment] In another embodiment, the above active material includes a polymer containing a repeating unit represented by the following General Formula (8), General Formula (9), General Formula (10), or General Formula (11), or a salt thereof. The above polymer or a salt thereof may be included in any of the reaction starting materials, products, and intermediate products in the discharge reaction of the battery electrode reaction. The above polymer or a salt thereof may be included in any of the reaction starting materials, products, and intermediate products in the charge reaction of the battery electrode reaction.

[0190] [General Formula (8)] [Chemical Formula]

[0191] In General Formula (8), R 801 ~R 806Each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 801 ~R 806 are linked to each other to form a ring represented by -OMO-. The double lines shown by solid and broken lines represent a single bond or a double bond. n is an integer of 2 or more indicating the degree of polymerization.

[0192] In this embodiment, at least four of R 801 ~R 806 are an oxygen atom or an OM group. The number of oxygen atoms or OM groups among R 801 ~R 806 may be an even number of 4 or more. All of R 801 ~R 806 may be an oxygen atom or an OM group.

[0193] Each of R 801 ~R 806 may have the same configuration as each of the above-described R 101 ~R 108 For example, each of R 801 ~R 806 independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. Also, each of R 801 ~R 806 may be determined such that the repeating unit represented by the general formula (8) has symmetry. Each of R 801 ~R 806 may be determined such that the repeating unit represented by the general formula (8) has a symmetry axis, a symmetry plane, or a center of symmetry.

[0194] According to this embodiment, since the charge storage site is included in the repeating unit, even when the degree of polymerization and the molecular weight of the polymer increase, the amount of charge that can be accumulated per unit mass does not fluctuate. Therefore, any degree of polymerization n can be adopted.

[0195] [General formula (9)] [Chemical formula]

[0196] In general formula (9), R 101 ~R 104 each independently represents an oxygen atom or a group represented by -OM. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R101 to R104 are connected to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. n is an integer of 2 or more indicating the degree of polymerization. R 101 ~R 104 may be as described in relation to general formula (1).

[0197] [General formula (10)] [Chemical formula]

[0198] In general formula (10), R 201 ~R 206 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 201 ~R 206 are connected to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. At least four of R 201 ~R 206 are an oxygen atom or a group represented by -OM. n is an integer of 2 or more indicating the degree of polymerization. R 201 ~R 206 may be as described in relation to general formula (2).

[0199] [General formula (11)] [Chemical formula]

[0200] In general formula (11), R 501 ~R 508 each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R 501 ~R 508 are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond. At least four of R 501 ~R 508 are an oxygen atom or a group represented by -OM. n is an integer of 2 or more indicating the degree of polymerization. R 501 ~R 508 Details may be as described in relation to general formula (5).

[0201] [Specific Examples of Compounds Used as Active Materials] The above active material may include a polymer containing a repeating unit represented by the following chemical formula (8-1) or a salt thereof. In chemical formula (8-1), n is an integer of 2 or more indicating the degree of polymerization.

[0202] [Chemical Formula (8-1)]

Chemical Structure

[0203] The polymer containing the repeating unit represented by chemical formula (8-1) corresponds to the state where the active material is fully charged. The polymer containing the repeating unit represented by chemical formula (8-1) may be an example of the fully oxidized form of the polymer containing the repeating unit represented by general formula (8). It should be noted that the following compounds are conjugated molecules and have resonance structures. The polymer containing the repeating unit represented by general formula (8) or a salt thereof is not limited to the polymer containing the repeating unit represented by chemical formula (8-1). As other specific examples, a fully reduced form or a partially reduced form of the polymer containing the repeating unit represented by chemical formula (8-1) may be exemplified.

[0204] [II. Method for Producing Living Substances] The above-mentioned living substances are known compounds or can be synthesized by adopting known reactions. For example, phenazine-1,4,6,9-tetraone represented by chemical formula (1A-1) can be synthesized according to the following reaction formula 4.

[0205] [Reaction Formula 4] [Chemical Formula]

[0206] For example, first, using 2,5-dimethoxyaniline (4a in Reaction Formula 4) and 1,4-dimethoxy-2-nitrobenzene (4b in Reaction Formula 4) as starting materials, 1,4,6,9-tetramethoxyphenazine (4c in Reaction Formula 4) can be obtained by a known method. For example, by dissolving the starting materials in a toluene solvent and refluxing in the presence of potassium tert-butoxide (t-BuOK), 1,4,6,9-tetramethoxyphenazine is produced.

[0207] Next, using 1,4,6,9-tetramethoxyphenazine as the starting material, phenazine-1,4,6,9-tetraone (4d in Reaction Formula 4) can be obtained by a known method. For example, by mixing a solution obtained by dissolving 1,4,6,9-tetramethoxyphenazine in an organic solvent with an aqueous solution of ammonium hexanitratocerate(IV), phenazine-1,4,6,9-tetraone is produced.

[0208] Also, phenazine-1,2,3,6,7,8-hexaone represented by chemical formula (1A-3) can be synthesized for its reduced form according to the following Reaction Formula 5 and Reaction Formula 6. The reduced form of phenazine-1,2,3,6,7,8-hexaone may be an example of the compound represented by chemical formula (1B-3).

[0209] Similarly, phenazine-1,2,3,4,6,7,8,9-octone represented by Chemical Formula (1A-4) can synthesize its partial reduction product according to the following Reaction Formula 5 and Reaction Formula 7. The partial reduction product of phenazine-1,2,3,4,6,7,8,9-octone may be an example of the compound represented by Chemical Formula (1B-4).

[0210] [Reaction Formula 5] [Chem.]

[0211] [Reaction Formula 6] [Chem.]

[0212] [Reaction Formula 7] [Chem.]

[0213] For example, first, in Reaction Formula 5, using 2,3,4,5-tetramethoxyaniline (5a in Reaction Formula 5) as a starting material, 1,2,3,6,7,8-hexamethoxyphenazine (5b in Reaction Formula 5) and (E)-1,2-bis(2,3,4,5-tetramethoxyphenyl)diazene (5c in Reaction Formula 5) can be obtained by a known method. For example, by dissolving the starting material in N,N-dimethylformamide (DMF) and heating and stirring it with a known catalyst, 1,2,3,6,7,8-hexamethoxyphenazine and (E)-1,2-bis(2,3,4,5-tetramethoxyphenyl)diazene are generated.

[0214] Next, in Reaction Formula 6, using 1,2,3,6,7,8 - hexamethoxyphenazine (5b in Reaction Formula 6) obtained by Reaction Formula 5 as a starting material, 1,2,3,6,7,8 - hexahydroxyphenazine (6a in Reaction Formula 6) is obtained by a known method. For example, by dissolving the starting material in a mixed solution of acetic acid - hydrobromic acid and heating and stirring at the reflux temperature, 1,2,3,6,7,8 - hexahydroxyphenazine is produced.

[0215] Similarly, in Reaction Formula 7, using (E)-1,2 - bis(2,3,4,5 - tetramethoxyphenyl)diazene (5c in Reaction Formula 7) obtained by Reaction Formula 5 as a starting material, 1,3,4,6,8,9 - hexahydroxyphenazine - 2,7 - dione (7a in Reaction Formula 7) is obtained by a known method. For example, by dissolving the starting material in a mixed solution of acetic acid - hydrobromic acid and heating and stirring at the reflux temperature, 1,3,4,6,8,9 - hexahydroxyphenazine - 2,7 - dione is produced.

[0216] It should be understood by those skilled in the art who are familiar with the description in this specification that compounds represented by General Formulas (1) to (7) and repeating units represented by General Formulas (8) to (11) can be synthesized by similar procedures. Also, those skilled in the art who are familiar with the description in this specification can understand that, if necessary, by adopting known reactions, compounds represented by General Formulas (1) to (7), repeating units represented by General Formulas (8) to (11), and polymers containing repeating units represented by General Formulas (8) to (11) can be synthesized.

Examples

[0217] [Example 1] Phenazine-1,4,6,9-tetraone was synthesized according to the procedure described in Conboy, Darren; Mirallai, Styliana I.; Craig, Austin; McArdle, Patrick; Al-Kinani, Ali A.; Barton, Stephen; Aldabbagh, Fawaz, Journal of Organic Chemistry, 2019, vol. 84, #15, p. 9811-9818. The details of the reaction conditions were determined in accordance with the above literature. Also, commercially available reagents were used for the various reagents used in the synthesis.

[0218] Specifically, first, 2,5-dimethoxyaniline and 1,4-dimethoxy-2-nitrobenzene were refluxed in toluene solvent for 16 hours in the presence of t-BuOK. The obtained solid was separated by column chromatography to obtain 1,4,6,9-tetramethoxyphenazine.

[0219] Next, the separated 1,4,6,9-tetramethoxyphenazine was dissolved in an appropriate solvent, mixed with an aqueous solution of ammonium hexanitratocerate(IV), and stirred at room temperature for one hour. Then, the organic layer was washed with water by liquid separation operation, and the solvent was distilled off to obtain phenazine-1,4,6,9-tetraone.

[0220] [Example 2] 1,2,3,6,7,8-Hexahydroxyphenazine, which is a reduced form of phenazine-1,2,3,6,7,8-hexaone [0], was synthesized according to the procedure described in Chem. Commun., 2016, 52, 922-925). The details of the reaction conditions were determined in accordance with the above literature. Also, commercially available reagents were used for the various reagents used in the synthesis.

[0221] Specifically, first, 2,3,4,5-tetramethoxyaniline was dissolved in DMF and heated with stirring in the presence of a suitable catalyst. Subsequently, 1,2,3,6,7,8-hexamethoxyphenazine and (E)-1,2-bis(2,3,4,5-tetramethoxyphenyl)diazene were obtained by a separation operation using column chromatography.

[0222] Next, the separated 1,2,3,6,7,8-hexamethoxyphenazine was dissolved in a mixed solution of acetic acid and hydrobromic acid and heated with stirring at the reflux temperature. After that, the above solution was cooled to room temperature and then 1,2,3,6,7,8-hexahydroxyphenazine was obtained by a filtration operation.

[0223] [Example 3] 1,3,4,6,8,9-Hexahydroxyphenazine-2,7-dione, a partial reduction product of phenazine-1,2,3,4,6,7,8,9-octone, was synthesized according to the procedure described in Chem. Commun., 2016, 52, 922-925). The details of the reaction conditions were determined based on the above literature. Also, commercially available reagents were used for various reagents used in the synthesis.

[0224] Specifically, in the same manner as in Example 2, first, 2,3,4,5-tetramethoxyaniline was dissolved in DMF and heated with stirring in the presence of a suitable catalyst. Subsequently, 1,2,3,6,7,8-hexamethoxyphenazine and (E)-1,2-bis(2,3,4,5-tetramethoxyphenyl)diazene were obtained by a separation operation using column chromatography.

[0225] Next, the separated (E)-1,2-bis(2,3,4,5-tetramethoxyphenyl)diazene was dissolved in a mixed solution of acetic acid and hydrobromic acid and heated with stirring at the reflux temperature. After that, the above solution was cooled to room temperature and then 1,3,4,6,8,9-hexahydroxyphenazine-2,7-dione was obtained by a filtration operation.

[0226] [Comparative Example 1] According to the procedure described in Yao, M., Taguchi, N., Ando, H. et al. "Improved gravimetric energy density and cycle life in organic lithium-ion batteries with naphthazarin-based electrode materials.", Commun Mater 1, 70 (2020), the naphthazarin dimer represented by the following chemical formula was synthesized. The details of the reaction conditions were determined in accordance with the above literature. Also, commercially available reagents were used for the various reagents used in the synthesis. [Chemical formula]

[0227] Specifically, first, 2,3-dichloronaphthazarin was prepared as a starting material. Next, the hydroxyl group of 2,3-dichloronaphthazarin was protected with an acetyl group by a reflux operation using acetic anhydride. Next, a dimerization reaction using ruberythric acid was carried out at 50 °C in the presence of triethylamine (TEA) and N,N-dimethylformamide (DMF). As a result, a compound having a dibenzo[b,i]thianthrene skeleton was obtained. Thereafter, hydrolysis was carried out at 70 °C in the presence of tetrahydrofuran. Also, it was neutralized using lithium hydroxide. As a result, the above naphthazarin dimer was obtained.

[0228] [Test Example 1] Using the phenazine-1,4,6,9-tetraone synthesized in Example 1 as a positive electrode active material, an R2032 coin-type battery was fabricated. The R2032 coin-type battery was fabricated by the following procedure.

[0229] First, phenazine-1,4,6,9-tetraone as a positive electrode active material, acetylene black (manufactured by Denka Co., Ltd.) as a conductive assistant, and PTFE (manufactured by Daikin Industries, Ltd.) as a binder were mixed at a ratio of positive electrode active material:conductive assistant:binder = 4:5:1 (mass ratio) to prepare a positive electrode active material sheet with a diameter of 10 mm and a thickness of 100 μm. The above positive electrode active material sheet was pressure-bonded to a stainless steel mesh (manufactured by Nilaco Corporation, SUS304) with a diameter of 14 mm and a thickness of 100 μm to prepare a positive electrode.

[0230] Next, a circular member with a diameter of 13 mm was cut out from a metal lithium foil with a thickness of 0.5 mm (manufactured by Honjo Metal Co., Ltd., purity 99.8% or more). The above member cut out from the lithium foil was pressure-bonded onto a stainless steel plate (manufactured by Takizawa Co., Ltd.) with a diameter of 15.5 mm and a thickness of 0.5 mm to prepare a negative electrode.

[0231] Also, as a separator, a glass filter (manufactured by Advantech Co., Ltd.) with a diameter of 16 mm and a thickness of 0.4 mm was prepared. As an electrolytic solution, a non-aqueous electrolytic solution (manufactured by Kishida Chemical Co., Ltd.) containing LiPF6 and a mixture of ethylene carbonate and diethyl carbonate was prepared. The above positive electrode, separator, negative electrode, and electrolytic solution were arranged inside a battery case conforming to the R2032 coin-type battery standard to prepare a coin-type battery for testing.

[0232] The mass of phenazine-1,4,6,9-tetraone contained in the coin-type battery for testing was 3 mg. Also, the mass of the coin-type battery for testing was 3.1 g. Regarding the prepared coin-type battery for testing, a charge-discharge test was conducted at a current density of 20 mA / g in an atmosphere of 30°C within a potential range of 4.5 - 1.2 V (vs. Li + / Li).

[0233] Figure 3 shows the initial discharge curve. Also, the initial discharge capacity was 580 [mAh / g - positive electrode active material]. The energy density of the coin-type battery for testing was 1.1 - 1.4 [Wh / g - coin-type battery].

[0234] [Test Example 2] Using the reduced form of phenazine-2,3,4,7,8,9-hexaone synthesized in Example 2 as the positive electrode active material, an R2032 coin-type battery was fabricated. A coin-type battery for testing was fabricated by the same procedure as in Test Example 1, except that (i) the reduced form of phenazine-2,3,4,7,8,9-hexaone synthesized in Example 2 was used as the positive electrode active material, and (ii) a non-aqueous electrolyte (manufactured by Kishida Chemical Co., Ltd.) containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and sulfolane (SL) was used as the electrolyte.

[0235] The mass of the reduced form of phenazine-2,3,4,7,8,9-hexaone contained in the coin-type battery for testing was 1 mg. Also, the mass of the coin-type battery for testing was 3.2 g. For the fabricated coin-type battery for testing, a charge-discharge test was conducted at a current density of 20 mA / g in an atmosphere of 30 °C within a potential range of 4.5 - 1.2 V (vs. Li + / Li).

[0236] Figure 4 shows the initial discharge curve. Also, the initial discharge capacity was 820 [mAh / g - positive electrode active material]. The energy density of the coin-type battery for testing was 1.5 [Wh / g - coin-type battery]. It should be noted that the above discharge capacity is considered to include contributions from components other than the active material.

[0237] [Test Example 3] Using the partially reduced form of phenazine-1,2,3,4,6,7,8,9-octaone synthesized in Example 3 as the positive electrode active material, an R2032 coin-type battery was fabricated. A coin-type battery for testing was fabricated by the same procedure as in Test Example 2, except that the partially reduced form of phenazine-1,2,3,4,6,7,8,9-octaone synthesized in Example 3 was used as the positive electrode active material.

[0238] The mass of the partially reduced form of phenazine-1,2,3,4,6,7,8,9-octone contained in the test coin-type battery was 2 mg. Also, the mass of the test coin-type battery was 3.2 g. For the fabricated test coin-type battery, at an ambient temperature of 30 °C and a current density of 20 mA / g, charge-discharge tests were carried out in the potential range of 4.5 - 1.2 V (vs. Li + / Li).

[0239] Figure 5 shows the initial discharge curve. Also, the initial discharge capacity was 880 [mAh / g - cathode active material]. The energy density of the test coin-type battery was 1.7 [Wh / g - coin-type battery]. Note that the above discharge capacity is considered to include contributions from components other than the active material.

[0240] [Test Example 4] An R2032 coin-type battery was fabricated using the naphthalazine dimer synthesized in Comparative Example 1 as the cathode active material. The R2032 coin-type battery was fabricated according to the following procedure.

[0241] First, a slurry composition was prepared by mixing the naphthalazine dimer as the cathode active material, acetylene black (manufactured by Denka Co., Ltd.) and carbon nanotubes (manufactured by JiangSu Cnano Technology Ltd.) as conductive aids, and PVDF (manufactured by Kuraray Co., Ltd.) as a binder. The cathode active material, acetylene black, carbon nanotubes, and binder were mixed at a ratio of cathode active material:acetylene black:carbon nanotubes:binder = 100:14:3:4 (mass ratio). Also, the ratio of the cathode active material, acetylene black, carbon nanotubes, and binder in the slurry composition was 83% by mass.

[0242] Next, the above slurry composition was applied to an aluminum foil (manufactured by Hozen Co., Ltd., thickness: 20 μm) that had been subjected to surface roughening treatment. After drying the slurry composition, it was punched out to a diameter of 14 mm to fabricate the cathode. The thickness of the cathode was 134 μm. The coating amount of the naphthalazine dimer was 4.3 mg / cm 2 .

[0243] Next, a circular member with a diameter of 13 mm was cut out from a metallic lithium foil with a thickness of 0.5 mm (manufactured by Honjo Metal Co., Ltd., purity 99.8% or more). The above-mentioned member cut out from the above-mentioned lithium foil was pressure-bonded onto a stainless steel plate (manufactured by Takizawa Co., Ltd.) with a diameter of 15.5 mm and a thickness of 0.5 mm to fabricate a negative electrode.

[0244] Also, as a separator, a glass filter paper with a diameter of 16 mm and a thickness of 0.4 mm (manufactured by Advantech Co., Ltd.) was prepared. As an electrolytic solution, a non-aqueous electrolytic solution containing LiTFSI and SL (manufactured by Kishida Chemical Co., Ltd.) was prepared. The above-mentioned positive electrode, separator, negative electrode, and electrolytic solution were arranged inside a battery case conforming to the specifications of an R2032 coin-type battery to fabricate a coin-type battery for testing.

[0245] The mass of naphthazarin dimer contained in the coin-type battery for testing was 3 mg. Also, the mass of the coin-type battery for testing was 3.2 g. Regarding the fabricated coin-type battery for testing, a charge-discharge test was conducted at a current density of 20 mA / g in a potential range of 4.5 - 1.2 V (vs. Li + / Li) in an atmosphere at 30°C.

[0246] The initial discharge capacity was 416 [mAh / g - positive electrode active material]. The energy density of the coin-type battery for testing was 1.1 [Wh / g - active material].

[0247] As shown in Test Examples 1 to 4, the secondary battery using the phenazines synthesized in Examples 1 to 3 as the positive electrode active material has a very large energy density compared to the secondary battery using the naphthazarin dimer synthesized in Comparative Example 1 as the positive electrode active material. Also, since the secondary battery using the various phenazines described above as the positive electrode active material has a large charge amount that can be accumulated per unit mass, it can be seen that it is particularly suitable for use in a power storage cell or battery mounted on an aircraft.

[0248] In the case of a secondary battery using the naphthazarin dimer synthesized in Comparative Example 1 as a positive electrode active material, the theoretical capacity of the naphthazarin dimer is 462 [mhA / g], and the maximum energy density of the active material alone obtained by multiplying it by 2.7 V, the average potential based on Li, is 1.3 W / g. The value actually observed is 1.1 Wh / g. Therefore, the upper limit of the energy density of the secondary battery is expected to be about 400 [Wh / kg-storage cell].

[0249] On the other hand, the compounds synthesized in Examples 1 to 3 have few atoms that are not directly involved in oxidation and reduction in the molecule. In addition, the compounds synthesized in Examples 1 to 3 do not contain atoms with relatively large atomic weights such as sulfur. As a result, it is presumed that the theoretical capacity of the compounds synthesized in Examples 1 to 3 is larger than that of naphthazarin dimer. Since the energy density of an active material is calculated as the product of the theoretical capacity and the average discharge potential, it is presumed that the energy density of the compounds synthesized in Examples 1 to 3 is also larger than that of naphthazarin dimer.

[0250] As described above, the compounds represented by any one of the general formulas (1) to (7) have few atoms that are not directly involved in oxidation-reduction in the molecule, similar to the compounds synthesized in Examples 1 to 3. In addition, the compounds represented by any one of the general formulas (1) to (7) do not contain atoms with relatively large atomic weights, such as sulfur, similar to the compounds synthesized in Examples 1 to 3. Therefore, by using the compounds represented by any one of the general formulas (1) to (7) or a salt thereof as a secondary battery active material (particularly as a positive electrode active material), a storage cell having an energy density of 500 [Wh / kg-storage cell] or more can be produced.

[0251] Similarly, the polymer containing a repeating unit represented by any one of the general formulas (8) to (11) described above has few atoms that do not directly participate in oxidation-reduction within the molecule, similar to the compounds synthesized in Examples 1 to 3. Further, the polymer containing a repeating unit represented by any one of the general formulas (8) to (11) does not contain atoms with a relatively large atomic weight such as sulfur, similar to the compounds synthesized in Examples 1 to 3. Therefore, by using the polymer containing a repeating unit represented by any one of the general formulas (8) to (11) or a salt thereof as an active material for a secondary battery (particularly, a positive electrode active material), a storage cell having an energy density of 500 [Wh / kg - storage cell] or more can be produced.

[0252] As described above, the present invention has been described using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the description of the claims that forms with such changes or improvements can also be included in the technical scope of the present invention.

[0253] It should be noted that the execution order of each process such as operations, procedures, steps, and stages in the devices, systems, programs, and methods shown in the claims, the specification, and the drawings is not explicitly indicated as "before" or "preceding" etc., and can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the specification, and the drawings, even if it is described using "first," "next," etc. for convenience, it does not mean that it is essential to implement in this order.

Explanation of reference numerals

[0254] 100 Aircraft, 110 Battery, 112 Storage Battery Cell, 120 Power Control Circuit, 130 Electric Motor, 140 Propeller, 150 Sensor, 160 Control Device, 212 Positive Electrode Case, 214 Negative Electrode Case, 216 Sealing Agent, 218 Metal Spring, 220 Positive Electrode, 222 Positive Electrode Current Collector, 224 Positive Electrode Active Material Layer, 230 Separator, 240 Negative Electrode, 242 Negative Electrode Current Collector, 244 Negative Electrode Active Material Layer, 250 Electrolyte

Claims

1. A cathode active material for a secondary battery, which is used as an active material of the secondary battery, wherein the active material contains a compound represented by the following general formula (1), general formula (2), general formula (3), general formula (4), general formula (4), general formula (5), general formula (6) or general formula (7), or a salt thereof, A cathode active material for a secondary battery. [General formula (1)] 【Chemical Formula 1】 (In general formula (1), R １０１ ~R １０８ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R １０１ ~R １０８ are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. At least six of R １０１ ~R １０８ are an oxygen atom or a group represented by -OM.) [General formula (2)] [Chemical Formula 2] (In general formula (2), R ２０１ to R ２１０ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R ２０１ to R ２１０ are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. At least six of R ２０１ to R ２１０ are an oxygen atom or a group represented by -OM.) [General formula (3)] 【Chemical Formula 3】 〔In general formula (3), R ３０１ ~R ３１０ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R ３０１ ~R ３１０ are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond. At least four of R ３０１ ~R ３１０ are an oxygen atom or a group represented by -OM.〕 [General formula (4)] [Chemical Formula 4] (In general formula (4), R ４０１ ~R ４１０ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R ４０１ ~R ４１０ are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. At least four of R ４０１ ~R ４１０ are an oxygen atom or a group represented by -OM.) [General formula (5)] [Chemical Formula 5] 〔In general formula (5), R ５０１ ~R ５１２ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R ５０１ ~R ５１２ are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid lines and broken lines represent a single bond or a double bond. At least four of R ５０１ ~R ５１２ are an oxygen atom or a group represented by -OM.〕 [General formula (6)] 【Chemical Formula 6】 (In general formula (6), R ６０１ ~R ６１２ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R ６０１ ~R ６１２ are linked to each other to form a ring represented by -OMO-. The double lines shown by solid and broken lines represent a single bond or a double bond. At least four of R ６０１ ~R ６１２ are an oxygen atom or a group represented by -OM.) [General formula (7)] 【Chemical Formula 7】 〔In general formula (7), R ７０１ ~R ７１２ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R ７０１ ~R ７１２ are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and broken lines represent a single bond or a double bond. At least four of R ７０１ ~R ７１２ are an oxygen atom or a group represented by -OM.〕

2. The compound has symmetry, The cathode active material for a secondary battery according to claim 1.

3. The compound is [Chemical 8] or its fully reduced form or partially reduced form, In the above chemical formula, R １ and R ２ each independently represents a hydrogen atom or an organic group. The cathode active material for a secondary battery according to claim 1.

4. A cathode active material for a secondary battery, which is used as an active material of the secondary battery, wherein the active material contains a compound represented by the following general formula (1) or a salt thereof, [General formula (1)] 【Chemical Formula 9】 〔In general formula (1), R １０１ ~R １０８ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom or an organic group. M represents a hydrogen atom, or a monovalent or divalent metal atom. However, when M is a divalent metal atom, two adjacent R １０１ ~R １０８ are linked to each other to form a ring represented by -OMO-. The double lines indicated by solid and dashed lines represent a single bond or a double bond. At least four of R １０１ ~R １０８ are an oxygen atom or a group represented by -OM.〕 The compound is 【Chemical 10】 or its fully reduced form in which all C=O in the 6-membered carbon ring becomes C-OM and all =N- in the pyrazine ring becomes -NM-, or its partially reduced form in which part of C=O in the 6-membered carbon ring and =N- in the pyrazine ring becomes C-OM or -NM-, In the above chemical formula, R １ and R ２ each independently represents a hydrogen atom or an organic group, A cathode active material for a secondary battery.

5. M is H, Li, Na, K, Mg or Ca, The cathode active material for a secondary battery according to any one of claims 1 to 4.

6. A cathode for a secondary battery, comprising the cathode active material for a secondary battery according to any one of claims 1 to 5. A cathode for a secondary battery.

7. A positive electrode active material layer containing a positive electrode active material, A negative electrode active material layer containing a negative electrode active material, An electrolyte, and wherein the positive electrode active material or the negative electrode active material contains the cathode active material for a secondary battery according to any one of claims 1 to 5, A secondary battery.

8. The positive electrode active material contains the cathode active material for a secondary battery according to any one of claims 1 to 5, The secondary battery according to claim 7.

9. The secondary battery is a non-aqueous secondary battery, The secondary battery according to claim 7 or claim 8.

10. A flying object, comprising the secondary battery according to any one of claims 7 to 9, and a propulsion device that generates propulsion force by using the electrical energy stored in the secondary battery. A flying object.

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