Active substance for secondary battery, electrode for secondary battery, secondary battery, and flight vehicle

Abstract

Provided is an active substance for a secondary battery, which can be used as an active substance of a secondary battery. The active substance contains a compound, or a salt thereof, represented by at least one of general formula (1), general formula (2), general formula (3), and general formula (4), which include oligomers in which multiple phenazine structures are bonded. Also provided is a secondary battery which includes a positive electrode active substance layer containing a positive electrode active substance, a negative electrode active substance layer containing a negative electrode active substance, and an electrolyte. The positive electrode active substance or the negative electrode active substance contains the active substance for a secondary battery.

Description

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

[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.

[0002] Patent Document 1 discloses an electrode active material for a non-aqueous secondary battery, which is an organic material exhibiting redox activity and is made of a compound in which a naphthazarin skeleton is condensed with a non-conjugated ring such as a dithiin ring. [Prior art documents] [Patent documents] [Patent document 1] JP 2018-085243 A General disclosure

[0003] In a first aspect of the present invention, there is provided an active material for a secondary battery, which is used as an active material for a secondary battery, and which contains at least one compound represented by the following general formula (1), general formula (2), general formula (3), or general formula (4), or a salt thereof:

[0004] [General formula (1)] In the general formula (1), R １１ , R at the end １２ , R １３ and R １４ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R １１ ~R １４ may be linked to each other to form a ring represented by -OMO-. The double line represented by a solid line and a dashed line may represent a single bond or a double bond. a1 may be an integer of 2 to 10. b1 and c1 may each independently be an integer of 1 to 3. When b1 and c1 are 2 or 3, the number of R １３ and R １４ are the same or different, R １３ and R １４ At least four of the may be oxygen atoms or groups represented by -OM.

[0005] [General formula (2)] In the general formula (2), R ２１ , R at the end ２２ , R２３ and R ２４ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ２１ ~R ２４ may be linked to each other to form a ring represented by -OMO-. L may be a direct bond or a divalent linker including an aromatic group, a double bond, or a triple bond. The double line shown by a solid line and a dashed line may represent a single bond or a double bond. a2 may be an integer from 2 to 10. b2 and c2 may each independently be an integer from 1 to 3. When b2 and c2 are 2 or 3, the number of R ２３ and R ２４ are the same or different, R ２３ and R ２４ At least four of the may be oxygen atoms or groups represented by -OM.

[0006] [General formula (3)] In the general formula (3), R ３１ , R at the end ３２ , R ３３ ~R ３６ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ３１ ~R ３６ may be linked to each other to form a ring represented by -OMO-. L may be a direct bond or a divalent linker including an aromatic group, a double bond, or a triple bond. The double lines shown as solid and dashed lines may represent a single bond or a double bond. a3 may be an integer of 1 to 5. b31, b32, c31, and c32 may each independently be an integer of 1 to 3. When b31, b32, c31, and c32 are 2 or 3, the number of R ３３ , R ３４ , R ３５ and R ３６ are the same or different, R ３３ and R ３４ At least four of the above and R３５ and R ３６ At least four of the may be oxygen atoms or groups represented by -OM.

[0007] [General formula (4)] In the general formula (4), R ４１ , R ４３ and R ４４ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ４１ , R ４３ and R ４４ may be linked to each other to form a ring represented by -OMO-. L may be a direct bond or a k-valent linker including an aromatic group, a double bond, or a triple bond. The double line shown by a solid line and a dashed line may represent a single bond or a double bond. a4 may be an integer of 1 to 5. b4 and c4 may each independently be an integer of 1 to 3. When b4 and c4 are 2 or 3, 2 or 3 R ４３ and R ４４ are the same or different, R ４３ and R ４４ At least four of the groups may be oxygen atoms or groups represented by -OM, and k may be an integer of 2 or greater.

[0008] The compound may be a compound represented by the following general formulas (5) to (8).

[0009] [General formula (5)] In the general formula (5), R １０１ , R at the end １０２ , R １０３ ~R １０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R １０１ ~R １０８が They may be linked together to form a ring represented by -OMO-. A double line represented by a solid line and a dashed line may represent a single bond or a double bond. R１０３ ~R １０８ At least four of the groups may be oxygen atoms or groups represented by -OM. a1 may be an integer of 2 to 10.

[0010] [General formula (6)] In the general formula (6), R ２０１ , R at the end ２０２ , R ２０３ ~R ２０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ２０１ ~R ２０８ may be linked together to form a ring represented by -OMO-. L may be a direct bond or a divalent linker containing an aromatic group, a double bond, or a triple bond. Double lines shown as solid and dashed lines may represent single or double bonds. R ２０３ ~R ２０８ At least four of the groups may be oxygen atoms or groups represented by -OM. a2 may be an integer of 2 to 10.

[0011] [General formula (7)] In the general formula (7), R ３０１ , R at the end ３０２ , R ３０３ ~R ３１４ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ３０１ ~R ３１４ may be linked together to form a ring represented by -OMO-. L may be a direct bond or a divalent linker containing an aromatic group, a double bond, or a triple bond. Double lines shown as solid and dashed lines may represent single or double bonds. R ３０３ ~R ３０８ At least four of the above and R ３０９ ~R ３１４At least four of the groups may be oxygen atoms or groups represented by -OM. a3 may be an integer of 1 to 5.

[0012] [General formula 8] In the general formula (8), R ４０１ , R ４０３ ~R ４０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ４０１ and R ４０３ ~R ４０８ may be linked together to form a ring represented by -OMO-. L may be a direct bond or a k-valent linker including an aromatic group, a double bond, or a triple bond. Double lines shown as solid and dashed lines may represent single or double bonds. R ４０３ ~R ４０８ At least four of the groups may be oxygen atoms or groups represented by -OM. a4 may be an integer of 1 to 5. k may be an integer of 2 or greater.

[0013] The compound may be a compound represented by the following general formula (9).

[0014] [General formula (9)] In the general formula (9), R ５０１ , R at the end ５０２ , R ５０３ ~R ５０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ５０１ ~R ５０８ may be linked to each other to form a ring represented by -OMO-. The double line represented by a solid line and a dashed line may represent a single bond or a double bond. a51 and a53 may each independently represent an integer of 1 to 5. b51, b52, b53, c51, c52, and c53 may each independently represent an integer of 1 to 3. When b51, b53, c51, and c53 are 2 or 3, 2 or 3 R ５０３, R ５０４ , R ５０７ and R ５０８ are the same or different, R ５０３ and R ５０４ At least four of the above and R ５０７ and R ５０８ At least four of may be oxygen atoms or groups represented by -OM. n and m may each be an integer of 1 to 3. The sum of n and b52, and the sum of m and c52 may each be 4 or less.

[0015] In the active material for a secondary battery, the compound may be symmetric.

[0016] In the above active material for a secondary battery, L may be a direct bond or an organic group including an arylene group, a heterocyclic group, an alkenylene group, or an alkynylene group.

[0017] In the active material for a secondary battery, the compound may be at least one of the compounds shown below, or a completely reduced product or a partially reduced product thereof.

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

[0019] In a second aspect of the present invention, there is provided an electrode for a secondary battery, the electrode for a secondary battery comprising the active material for a secondary battery.

[0020] In a third aspect of the present invention, there is provided a secondary battery. The secondary battery may have 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. The positive electrode active material or the negative electrode active material may contain the active material for a secondary battery.

[0021] In the secondary battery, the positive electrode active material may include the active material for secondary batteries.

[0022] The secondary battery may be a non-aqueous secondary battery.

[0023] In a fourth aspect of the present invention, there is provided an aircraft, which may include the secondary battery and a thrust generating device that generates thrust using the electrical energy stored in the secondary battery.

[0024] The above summary of the invention does not list all of the features of the present invention, and subcombinations of these features may also be inventions.

[0025] 1A and 1B are schematic diagrams showing an example of the system configuration of an aircraft 100. 1A and 1B are schematic diagrams showing an example of a storage cell 112. 1B shows the transition of the capacity retention rate in a charge / discharge test of the secondary battery of this embodiment. 1C shows the transition of the capacity retention rate in a charge / discharge test of the secondary battery of this embodiment.

[0026] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0027] 1 schematically illustrates an example of the system configuration of an aircraft 100. In this 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 this embodiment, the storage battery 110 includes one or more storage cells 112.

[0028] In this embodiment, the flying object 100 flies using electrical energy stored in the storage battery 110. Examples of the flying object 100 include an airplane, an airship, a balloon, a helicopter, a drone, and the like.

[0029] In this 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. The storage battery 110 also supplies the electrical energy stored in the one or more storage cells 112 to the electric motor 130 via the power control circuit 120.

[0030] In this embodiment, the storage cell 112 stores electric energy (sometimes referred to as charging the storage cell 112). The storage cell 112 also releases the stored electric energy (sometimes referred to as discharging the storage cell 112). The storage cell 112 may be a secondary battery. The storage cell 112 may be a non-aqueous secondary battery.

[0031] 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, etc. Furthermore, a lithium ion secondary battery, which is one aspect of a non-aqueous secondary battery, may be a concept that includes non-aqueous lithium ion secondary batteries that use a non-aqueous electrolyte and all-solid-state lithium ion secondary batteries that use a solid electrolyte.

[0032] For example, a material that can store a large amount of charge per unit volume is often selected as the active material for a secondary battery mounted on a vehicle. On the other hand, in this embodiment, the storage cell 112 is mounted on the aircraft 100. Therefore, it is preferable that the active material used in the storage cell 112 be a material that can store a large amount of charge per unit mass.

[0033] The mass energy density of the storage cell 112 is preferably 500 [Wh / kg-storage cell] or more, more preferably 550 [Wh / kg-storage cell] or more, even more preferably 600 [Wh / kg-storage cell] or more, still more preferably 650 [Wh / kg-storage cell] or more, and even more preferably 700 [Wh / g-storage cell] or more. This results in a storage cell that is particularly suitable for use as a power source for an aircraft.

[0034] The volume energy density of the storage cell 112 is 300 [Wh / m ３ -Storage cell] or more than 1200 [Wh / m ３ -storage cell] or less, and 400 [Wh / m ３ -Storage cell] or more than 1000 [Wh / m ３When the storage cell 112 is mounted on the aircraft 100 as part of the power supply of the aircraft 100, the volumetric energy density of the storage cell 112 may be 600 [Wh / m ３ -storage cell] or less, and 800 [Wh / m ３ -storage cell] or less.

[0035] The energy storage cell 112 may have a mass energy density within the above-mentioned ranges and a volume energy density within the above-mentioned ranges. This allows the energy storage cell, which is relatively difficult to use as a power source for a vehicle, to be used as a power source for an aircraft. Details of the energy storage cell 112 will be described later.

[0036] In this embodiment, the power control circuit 120 controls the input and output of power to the storage battery 110. The power control circuit 120 may control the input and output of power to the storage battery 110 based on commands from the control device 160. The power control circuit 120 includes, for example, a plurality of switching elements that operate based on control signals from the control device 160.

[0037] In this 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. In this way, the electric motor 130 can generate thrust for the aircraft 100 using the electrical energy stored in the storage cell 112.

[0038] In this embodiment, the sensor 150 measures various physical quantities related to the position and attitude of the flying object 100. Examples of sensors for measuring various physical quantities related to the position and attitude of the flying object 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.

[0039] In this embodiment, the control device 160 controls the air vehicle 100. The control device 160 may control the input and output of power to 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. This allows the control device 160 to control the position and attitude of the air vehicle 100. The control device 160 may control the position and attitude of the air vehicle 100 by controlling the power control circuit 120 based on the output from the sensor 150.

[0040] 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 thrust generating device.

[0041] 2 is a schematic diagram of an example of the storage cell 112. In this embodiment, the storage cell 112 will be described in detail using as an example a case where the storage cell 112 is a coin-type non-aqueous secondary battery.

[0042] [Electricity Storage Cell] In this embodiment, the energy storage cell 112 includes a positive electrode case 212, a negative electrode case 214, a sealant 216, and a metal spring 218. The energy storage cell 112 also includes a positive electrode 220, a separator 230, a negative electrode 240, and an electrolyte 250. In this embodiment, the positive electrode 220 includes a positive electrode current collector 222 and a positive electrode active material layer 224. In this embodiment, the negative electrode 240 includes a negative electrode current collector 242 and a negative electrode active material layer 244.

[0043] 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. A metal spring 218, a positive electrode 220, a separator 230, a negative electrode 240, and an electrolyte 250 are accommodated inside the space formed by the positive electrode case 212 and the negative electrode case 214. 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.

[0044] The positive electrode case 212 and the negative electrode case 214 are made of, for example, a thin, disc-shaped plate made of a conductive material. In this embodiment, the sealant 216 seals the gap formed between the positive electrode case 212 and the negative electrode case 214. The sealant 216 includes an insulating material. The sealant 216 insulates the positive electrode case 212 and the negative electrode case 214 from each other.

[0045] [Positive Electrode] In this embodiment, the positive electrode current collector 222 holds the positive electrode active material layer 224. Examples of materials for the positive electrode current collector 222 include aluminum, stainless steel, nickel, titanium, and alloys thereof. Examples of the shape of the positive electrode current collector 222 include foil, mesh, punched metal, and expanded metal. 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 also be 6 to 20 μm.

[0046] In this 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 may be 2 to 200 μm, per surface of the positive electrode current collector 222. The positive electrode active material layer 224 includes, for example, a positive electrode active material and a binding agent (sometimes referred to as a binder). The positive electrode active material layer 224 may also include a conductive additive.

[0047] In one embodiment, the positive electrode active material layer 224 is formed by applying a paste containing materials 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 organic solvent is not particularly limited, but an example of the organic solvent is N-methylpyrrolidone (NMP). In another embodiment, the positive electrode active material layer 224 is formed by mixing the materials constituting the positive electrode active material layer 224, forming the mixture into a sheet, and pressing the sheet-like mixture onto at least one surface of the positive electrode current collector 222.

[0048] The positive electrode active material layer 224 may contain, as a 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 heterocyclic compound may be a compound containing one or more phenazine structures. The phenazine structure (i) contains one pyrazine ring and two benzene rings, and (ii) each of the two benzene rings is connected to the pyrazine ring by sharing one carbon-carbon bond with the pyrazine ring. The pyrazine ring may be substituted with any functional group or may be unsubstituted. The benzene ring may be substituted with any functional group or may be unsubstituted.

[0049] The heterocyclic compound preferably includes a structure in which at least four oxygen atoms are bonded to the benzene ring. This allows the heterocyclic compound to store a large amount of charge even with a small molecular weight. As a result, by using the heterocyclic compound as a positive electrode active material, a storage cell with a large energy density per unit mass of the storage cell can be obtained.

[0050] The heterocyclic compound preferably has a structure in which an even number of oxygen atoms, 4 or more, are bonded to the benzene ring.

[0051] The positive electrode active material layer 224 may contain a phenazine as a positive electrode active material. The phenazine is preferably a compound having at least four oxygen atoms bonded to a benzene ring contained in a phenazine structure. As described above, this allows for a storage cell with a high energy density per unit mass of the storage cell to be obtained.

[0052] The phenazines are preferably compounds having an even number of oxygen atoms, 4 or more, bonded to the benzene ring. The phenazines may be compounds having an even number of oxygen atoms, 4 or more and 8 or less, bonded to the benzene ring. This improves the chemical stability of the heterocyclic compound.

[0053] The positive electrode active material layer 224 may contain, as the positive electrode active material, an oligomer in which a plurality of phenazine structures are bonded. The oligomer may be an oligomer in which a plurality of phenazine structures are bonded via a linker. This suppresses dissolution of the positive electrode active material in the electrolyte during charge and discharge, thereby improving the cycle performance of the secondary battery.

[0054] The positive electrode active material is, for example, a heterocyclic compound containing one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof. The 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.

[0055] The above-mentioned heterocyclic compounds or their salts or derivatives, phenazines and their oligomers are included, for example, in any of the reaction starting materials, products, and intermediate products in at least the discharge reaction of a battery electrode reaction. The details of the phenazine oligomers or their salts or derivatives that can be used as the positive electrode active material will be described later.

[0056] The positive electrode active material is not limited to the above heterocyclic compounds, etc. When the storage cell 112 is a lithium ion secondary battery or a lithium metal secondary battery, other examples of the positive electrode active material include LiMnO ２ , LiNiO ２ , LiCoO ２ , Li(Mn ｘ Ni １－ｘ ) O ２ , Li(Mn ｘ Co １－ｘ ) O ２ , Li(Ni ｙ Co １－ｙ ) O ２ , Li(Mn ｘ Ni ｙ Co １－ｘ－ｙ ) O ２ Layered oxides such as Li ２ MnO ３ -LiNiO ２ , Li ２ MnO ３ -LiCoO ２ , Li ２ MnO ３ -Li(Ni ｙCo １－ｙ ) O ２ Solid solutions of Li ２ MnSiO ４ , Li ２ NiSiO ４ , Li ２ CoSiO ４ , Li ２ (Mn ｘ Ni １－ｘ ) SiO ４ , Li ２ (Mn ｘ Co １－ｘ ) SiO ４ , Li ２ (Ni ｙ Co １－ｙ ) SiO ４ , Li ２ (Mn ｘ Ni ｙ Co １－ｘ－ｙ ) SiO ４ Silicates such as LiMnBO ３ , LiNiBO ３ , LiCoBO ３ , Li(Mn ｘ Ni １－ｘ ) BO ３ , Li(Mn ｘ Co １－ｘ ) BO ３ , Li(Ni ｙ Co １－ｙ ) BO ３ , Li(Mn ｘ Ni ｙ Co １－ｘ－ｙ ) BO ３ Borates such as V ２ O ５ ; LiV ３ O ６ MnO, etc. In the above formula, 0<x<1, 0<y<1, 0<x+y<1. These positive electrode active materials may be used alone, or two or more positive electrode active materials may be used in combination.

[0057] When the storage cell 112 is a sodium ion secondary battery, another example of the positive electrode active material is NaFeO ２ , NaNiO ２ , NaCoO ２ , NaMnO ２ , NaVO２ , Na(Ni Ｘ Mn １－Ｘ ) O ２ , Na(Fe Ｘ Mn １－Ｘ ) O ２ , NaVPO ４ F, Na ２ FePO ４ F, Na ３ V ２ (P.O. ４ ) ３ In the above formula, 0<x<1. These positive electrode active materials may be used alone, or two or more positive electrode active materials may be used in combination.

[0058] In this embodiment, the binder binds together materials (e.g., a positive electrode active material, a conductive additive, etc.) that constitute the positive electrode active material layer 224, and maintains the electrode shape of the positive electrode 220. The type of binder is not particularly limited, but examples of the binder include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyacrylic acid, and styrene butadiene rubber.

[0059] In this embodiment, the conductive additive reduces the resistance of the positive electrode 220. The type of conductive additive is not particularly limited as long as it has the desired electronic conductivity, and an example of the conductive additive is a carbon material. Examples of carbon materials include graphite, carbon black (e.g., acetylene black, ketjen black, etc.), coke, amorphous carbon, carbon fiber, carbon nanotubes, and graphene. These conductive additives may be used alone, or two or more types of conductive additives may be used in combination.

[0060] 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 mass %, more preferably 70 to 97 mass %, and even more preferably 80 to 95 mass %. The content of the binder in the positive electrode active material layer 224 is preferably 1 to 60 mass %, more preferably 3 to 30 mass %, and even more preferably 5 to 20 mass %.

[0061] 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 mass%, more preferably 1 to 10 mass%, and even more preferably 2 to 6 mass%. In this case, the content of the positive electrode active material in the positive electrode active material layer 224 is preferably 60 to 98 mass%, more preferably 70 to 96 mass%, and even more preferably 80 to 94 mass%. Furthermore, the content of the binder in the positive electrode active material layer 224 is preferably 1.8 to 39.8 mass%, more preferably 3 to 29 mass%, and even more preferably 4 to 18 mass%.

[0062] The content of the binder in the positive electrode active material layer 224 may be 1 to 20 mass %, 2 to 10 mass %, or 3 to 6 mass %. In this case, the remainder of the positive electrode active material layer 224 may be the positive electrode active material, or may be a mixture of the positive electrode active material and a conductive additive.

[0063] [Separator] In this embodiment, the separator 230 separates the positive electrode 220 and the negative electrode 240. The separator 230 ensures ionic conductivity between the positive electrode 220 and the negative electrode 240, for example, by retaining an electrolyte solution. Examples of materials for the separator 230 include polyethylene, polypropylene, an ethylene-propylene copolymer, glass, or a composite thereof. Examples of the shape of the separator 230 include a microporous film, a nonwoven fabric, a filter, and the like. 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%.

[0064] [Negative Electrode] In this embodiment, the negative electrode current collector 242 holds the negative electrode active material layer 244. Examples of materials for the negative electrode current collector 242 include copper, aluminum, stainless steel, nickel, titanium, and alloys 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 resin include polyethylene, polypropylene, polyethylene terephthalate, and polyimide. The metal layer may be a layer made of copper, aluminum, stainless steel, nickel, titanium, or an alloy thereof. The 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.

[0065] When lithium metal is used as the negative electrode active material, the lithium metal can also serve as a current collector. Therefore, when the power storage cell 112 is a lithium metal secondary battery, the power storage cell 112 does not need to include the negative electrode current collector 242.

[0066] Examples of the shape of the negative electrode current collector 242 include foil, mesh, punched metal, and expanded metal. 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.

[0067] 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 may be 2 to 200 μm, per surface 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 also contain a conductive additive.

[0068] In one embodiment, the negative electrode active material layer 244 is formed by applying a paste containing materials 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 organic solvent is not particularly limited, and an example of the organic solvent is N-methylpyrrolidone (NMP). In another embodiment, the negative electrode active material layer 244 is formed by mixing the materials constituting the negative electrode active material layer 244, forming the mixture into a sheet, and pressing the sheet-like mixture onto at least one surface of the negative electrode current collector 242.

[0069] The negative electrode active material layer 244 may contain, as the negative electrode active material, a heterocyclic compound including one or more pyrazine rings and two or more benzene rings, or a salt or derivative thereof. The heterocyclic compound may be a compound including one or more phenazine structures. The phenazine structure (i) includes one pyrazine ring and two benzene rings, and (ii) each of the two benzene rings is connected to the pyrazine ring by sharing one carbon-carbon bond with the pyrazine ring. The pyrazine ring may be substituted with any functional group or may be unsubstituted. The benzene ring may be substituted with any functional group or may be unsubstituted.

[0070] Similar to the heterocyclic compounds described in relation to the positive electrode active material layer 224, the heterocyclic compounds that can be used in the negative electrode active material layer 244 are preferably compounds having at least four oxygen atoms bonded to the above-mentioned benzene ring. The above-mentioned heterocyclic compounds are preferably compounds having four or more even-numbered oxygen atoms bonded to the above-mentioned benzene ring. The above-mentioned heterocyclic compounds may be compounds having four or more even-numbered oxygen atoms bonded to the above-mentioned benzene ring.

[0071] The negative electrode active material layer 244 may contain a phenazine as the negative electrode active material. The phenazine is preferably a compound having at least four oxygen atoms bonded to a benzene ring contained in a phenazine structure. The phenazine structure is preferably a compound having an even number of oxygen atoms, 4 or more, bonded to the benzene ring. The phenazine structure may be a compound having an even number of oxygen atoms, 4 or more and 8 or less, bonded to the benzene ring.

[0072] The negative electrode active material may include an oligomer in which a plurality of phenazine structures are bonded. The oligomer may be an oligomer in which a plurality of phenazine structures are bonded via a linker. This suppresses dissolution of the positive electrode active material in the secondary battery in the electrolyte and improves the cycle performance of the secondary battery.

[0073] The heterocyclic compounds or their salts or derivatives, and the phenazines and their oligomers are, for example, included in any of the starting materials, products, and intermediate products in at least the charging reaction of a battery electrode reaction. The phenazine oligomers or their salts or derivatives that can be used as negative electrode active materials will be described in detail later.

[0074] The negative electrode active material is not limited to the above heterocyclic compounds, etc. When the power storage cell 112 is a lithium ion secondary battery, other examples of the negative electrode active material include (i) graphite, (ii) non-sinterable carbon or non-graphitizable carbon, (iii) tin, silicon, and alloys containing these, and (iv) SiO. When materials such as (i) graphite, (ii) non-sinterable carbon or non-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.

[0075] The negative electrode active material may be a lithium-containing material 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 types of negative electrode active materials may be used in combination.

[0076] The negative electrode active material layer 244 may include lithium metal foil, which supplies lithium to the power storage cell 112. The thickness of the lithium metal foil may be 1 to 300 μm, 2 to 200 μm, or 3 to 100 μm. The thickness and / or mass of the lithium metal foil may be determined depending on the content of the positive electrode active material in the positive electrode active material layer 224.

[0077] When the power storage cell 112 is a sodium-ion secondary battery, other examples of the negative electrode active material include (i) graphite, (ii) non-sinterable carbon or non-graphitizable carbon, (iii) tin, silicon, and alloys containing these, and (iv) titanium oxide. The negative electrode active material may be a sodium-containing material 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 used in combination.

[0078] In this embodiment, the binder binds together materials (e.g., anode active material, conductive additive, etc.) that make up the anode active material layer 244, and maintains the electrode shape of the anode 240. The type of binder is not particularly limited, but examples of the binder include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyacrylic acid, and styrene butadiene rubber.

[0079] In this embodiment, the conductive additive reduces the resistance of the negative electrode 240. The type of conductive additive is not particularly limited as long as it has the desired electronic conductivity, and an example of the conductive additive is a carbon material. Examples of carbon materials include graphite, carbon black (e.g., acetylene black, ketjen black, etc.), coke, amorphous carbon, carbon fiber, carbon nanotubes, and graphene. These conductive additives may be used alone, or two or more types of conductive additives may be used in combination.

[0080] When the negative electrode active material layer 244 does not contain a conductive additive, the content of the negative electrode active material in the negative electrode active material layer 244 is preferably 40 to 99 mass %, more preferably 80 to 98.5 mass %, and even more preferably 90 to 98 mass %. The content of the binder in the negative electrode active material layer 244 is preferably 1 to 60 mass %, more preferably 1.5 to 20 mass %, and even more preferably 2 to 10 mass %.

[0081] When the negative electrode active material layer 244 contains a conductive additive, the content of the conductive additive in the negative electrode active material layer 244 is preferably 0.1 to 20 mass%, more preferably 1 to 10 mass%, and even more preferably 2 to 5 mass%. In this case, the content of the negative electrode active material in the negative electrode active material layer 244 is preferably 40 to 98 mass%, more preferably 80 to 97 mass%, and even more preferably 90 to 96 mass%. Furthermore, the content of the binder in the negative electrode active material layer 244 is preferably 1.9 to 59.9 mass%, more preferably 2 to 19 mass%, and even more preferably 2 to 8 mass%.

[0082] The content of the binder in the negative electrode active material layer 244 may be 0.1 to 5 mass %, 0.2 to 3 mass %, or 0.5 to 1 mass %. In this case, the remainder of the negative electrode active material layer 244 may be the negative electrode active material, or may be a mixture of the negative electrode active material and a conductive additive.

[0083] [Electrolyte] In this embodiment, the electrolytic solution 250 realizes ionic conduction between the positive electrode active material and the negative electrode active material via the electrolyte contained in the electrolytic solution 250. According to this embodiment, a non-aqueous electrolytic solution is used as the electrolytic solution 250. As the non-aqueous electrolytic solution, a known organic electrolytic solution may be used. For example, when the power storage cell 112 is a lithium ion secondary battery or a lithium metal secondary battery, (i) a solvent consisting of one or more of ethylene carbonate, dimethyl carbonate, diethyl carbonate, etc., and (ii) lithium perchlorate, LiPF ６ A solution in which a lithium salt such as the above is dissolved is used as the electrolyte solution 250.

[0084] The non-aqueous electrolyte contains, for example, a metal salt and a non-aqueous solvent. Examples of the metal salt include sodium salt and lithium salt. Examples of the sodium salt include NaPF ６ , NaBF ４ , NaClO ４ and NaAsF ６ Inorganic sodium salts such as NaCF ３ SO ３ , NaN(CF ３ SO ２ ) ２ , NaN(C ２ F ５ SO ２ ) ２ , NaC(CF ３ SO ２ ) ３ Examples of the lithium salt include organic sodium salts such as LiPF ６ , LiBF ４ , LiClO ４ , LiAsF ６ Inorganic lithium salts such as LiCF ３ SO ３ , LiN(CF ３ SO ２ ) ２ , LiN(C ２ F ５ SO ２ ) ２ , LiC(CF ３ SO ２ ) 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.

[0085] 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 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 in the range of 1.0 mol / L to 1.5 mol / L.

[0086] [Example of Another Embodiment] In this embodiment, the details of the storage cell 112 have been described using the example where the storage cell 112 is a coin-type secondary battery. However, the type, structure, and the like of the storage cell 112 are not limited to this embodiment. In another embodiment, the storage cell 112 may be a cylindrical battery including a wound electrode assembly in which a positive electrode, a separator, and a negative electrode are wound in a spiral shape. In yet another embodiment, the storage cell 112 may be a laminated battery in which a laminated electrode assembly in which positive electrodes and negative electrodes are alternately stacked with separators sandwiched between them is sealed with a laminate.

[0087] In this embodiment, the details of the energy storage cell 112 have been described using as an example a case where the anode 240 includes the anode current collector 242 and the anode active material layer 244. However, the anode of the energy storage cell 112 is not limited to this embodiment. In other embodiments, for example, when the energy storage cell 112 is a lithium metal secondary battery, metallic lithium may be used as the anode.

[0088] In this embodiment, an example of the storage cell 112 has been described using the electrolytic solution 250 as the electrolyte of the storage cell 112. However, the electrolyte of the storage cell 112 is not limited to this embodiment. In other embodiments, a solid electrolyte or a gel electrolyte may be used as the electrolyte of the storage cell 112. The solid electrolyte may be Li ２ S-P ２ S ５ system, Li ２ S-GeS ２ -P ２ S ５Examples include inorganic solid electrolytes such as those based on the above-mentioned system.

[0089] As described above, the details of the aircraft 100 and the storage cell 112 have been described using Figures 1 and 2. Next, the active material for a secondary battery used as the positive electrode active material or the negative electrode active material will be described in detail.

[0090] [I. Active Material] As described above, according to this embodiment, an oligomer in which a plurality of phenazine structures are bonded is used as a positive electrode active material or a negative electrode active material (sometimes simply referred to as an active material) for a secondary battery.

[0091] In this embodiment, the active material includes at least one compound represented by the following general formula (1), general formula (2), general formula (3), and general formula (4), or a salt thereof. The compound or a salt thereof may be included in any of the starting material, product, and intermediate product in the discharge reaction of a battery electrode reaction. The compound or a salt thereof may be included in any of the starting material, product, and intermediate product in the charge reaction of a battery electrode reaction.

[0092] [General formula (1)] In the general formula (1), R １１ , R at the end １２ , R １３ and R １４ may each independently represent an oxygen atom, a group represented by -OM (sometimes referred to as an OM group), a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. In the OM group, the bond between O and the metal atom may be an ionic bond.

[0093] When M is a divalent metal atom, two adjacent R １１ ~R １４ may be linked to each other to form a ring represented by -OMO-. １１ is R １１ R bonded to the benzene ring to which １３ and R １２ is R １２ R bonded to the benzene ring to which １４ For example, when M is Mg, R１１ and the adjacent R １３ and may form a ring represented by -OMgO-.

[0094] The double line shown by a solid line and a dashed line represents a single bond or a double bond. In general formula (1), the single bond and the double bond may be arranged so that the compound is a conjugated molecule and has a resonance structure.

[0095] In this embodiment, the square brackets in the chemical formula represent repeating units in the molecule. The solid and dashed lines passing through the square brackets represent bonds between repeating units or between repeating units and terminal groups (in the case of general formula (1), R １１ and R １２ ) is shown.

[0096] In general formula (1), a1 represents the number of repeating units of the phenazine structure. a1 may be an integer of 2 to 10. When a1 is within this range, dissolution of the active material into the electrolyte during charge and discharge can be suppressed, improving the cycle performance of the secondary battery. In addition, a decrease in the crystallinity of the active material and a decrease in electronic conductivity can be suppressed.

[0097] In general formula (1), b1 and c1 may each independently be an integer of 1 to 3. When b1 and c1 are 2 or 3, R １３ and R １４ are the same or different, R １３ and R １４ At least four of R may be oxygen atoms or groups represented by -OM. １３ and R １４ The number of oxygen atoms or OM groups in R may be an even number of 4 or more. １３ and R １４ may all be oxygen atoms or OM groups.

[0098] This increases the number of electrons involved in the redox reaction. Specifically, a multi-electron reaction involving four or more electrons becomes possible in the redox reaction, increasing the theoretical capacity of the active material. Therefore, the active material can store more charge even with a small molecular weight. As a result, a storage cell with a high energy density per unit mass can be obtained.

[0099] When the active material is fully charged, １１ ~R １４ The bond between the oxygen atom contained in and the carbon of the benzene ring contained in the phenazine structure is a double bond. In this case, the nitrogen atom contained in the pyrazine ring of the phenazine structure is not bonded to the atom represented by M described above. For example, no hydrogen ion or metal ion is bonded to the nitrogen atom.

[0100] On the other hand, when the active material is fully discharged, the R １１ ~R １４ All oxygen atoms contained in the OM group exist as OM groups, and the bond between the oxygen atom of the OM group and the carbon of the benzene ring contained in the phenazine structure is a single bond. At this time, the 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 nitrogen atom.

[0101] R １１ From R １４ The organic group represented by R may be a substituted or unsubstituted hydrocarbon group. The hydrocarbon group may be a monovalent hydrocarbon group. １１ From R １４ In the organic group represented by the formula: two adjacent organic groups may be linked to each other to form a ring.

[0102] Examples of the organic group include a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted carboxy group, a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted acyl group, a substituted or unsubstituted acyloxy group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryl group, a substituted or unsubstituted heteroaryloxy group, a substituted or unsubstituted ester group, a substituted or unsubstituted ether group, a substituted or unsubstituted amino group, a substituted or unsubstituted sulfonic acid group, a substituted or unsubstituted cyano group, and a substituted or unsubstituted thioether group. The organic group may be a monovalent group having an ester bond (-COO-) or a monovalent group having an ether bond (-O-). The organic group may contain boron. The organic group may contain boron as a heteroatom.

[0103] The 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 smaller atomic weights than, for example, sulfur. Therefore, when the 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 storage cell is improved. The organic group may be composed of one or more atoms selected from the group consisting of carbon, hydrogen, oxygen, and nitrogen.

[0104] When the number of electrons involved in the oxidation-reduction reaction in the active material is the same, the amount of charge that can be stored per unit mass decreases as the molecular weight of the active material increases. Therefore, when the 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 organic group may be 1.

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

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

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

[0108] R １１ From R １４ In the OM group represented by the formula (I), 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.

[0109] As described above, when the number of electrons involved in the redox reaction in the active material is the same, the amount of charge that can be stored per unit mass decreases as the molecular weight of the active material increases. Therefore, the smaller the ratio of the molecular weight of the compound represented by general formula (1) to the number of electrons involved in the redox reaction in the compound, the higher the volumetric energy density of the compound can be. Considering the ease of synthesis and the amount of charge that can be stored per unit mass, R１１ From R １４ Among these, those other than the oxygen atom or the OM group are preferably hydrogen atoms.

[0110] The above general formula (1) may be represented by the following chemical formula (1A), for example: [Chemical formula (1A)]

[0111] [General formula (2)] In the general formula (2), R ２１ , R at the end ２２ , R ２３ and R ２４ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ２１ ~R ２４ may be linked to each other to form a ring represented by -OMO-. The ring represented by -OMO- may have the same structure as -OMO- described above for general formula (1).

[0112] L is a direct bond or a divalent linker containing an aromatic group, a double bond, or a triple bond. The linker may be an organic group containing an arylene group, a heterocyclic group, an alkenylene group, or an alkynylene group. The linker may be, for example, a phenylene group, an ethene-1,2-diyl group, or an acetylene-1,2-diyl group. In general formula (2), L may be the same or different for each repeating unit described in square brackets.

[0113] Double lines, shown as solid and dashed lines, indicate single or double bonds. The single and double bonds may be arranged such that the compounds are conjugated molecules and have resonance structures.

[0114] In general formula (2), a2 represents the number of repeating units each consisting of a phenazine structure and a linker contained in the oligomer, and may be an integer of 2 to 10.

[0115] In general formula (2), b2 and c2 may each independently be an integer of 1 to 3. When b2 and c2 are 2 or 3, R ２３ and R２４ are the same or different, R ２３ and R ２４ At least four of R may be oxygen atoms or groups represented by -OM. ２３ and R ２４ The number of oxygen atoms or OM groups in R may be an even number of 4 or more. ２３ and R ２４ may all be oxygen atoms or OM groups.

[0116] R ２１ From R ２４ Each of the above-described R １１ From R １４ For example, R ２１ From R ２４ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. ２１ From R ２４ Each of R can be determined so that the compound represented by general formula (2) has symmetry. ２１ From R ２４ may be determined so that the compound represented by general formula (2) has an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0117] The above general formula (2) may be represented by, for example, the following chemical formula (2A): [Chemical formula (2A)]

[0118] [General formula (3)] In the general formula (3), R ３１ , R at the end ３２ , R ３３ ~R ３６ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ３１ ~R ３６ may be linked to each other to form a ring represented by -OMO- (R ３１ is R ３１ R contained in the benzene ring to which ３３ may be connected with R ３２ is R３２ R contained in the benzene ring to which ３６ The ring represented by -OMO- may have the same structure as -OMO- described above for general formula (1).

[0119] L is a direct bond or a divalent linker containing an aromatic group, a double bond, or a triple bond. Solid and dashed double lines indicate single or double bonds. The single and double bonds may be arranged such that the compound is a conjugated molecule and has a resonance structure.

[0120] In general formula (3), a3 represents the number of repeating units of the phenazine structure bonded via the linker described in square brackets, and may be an integer of 1 to 5.

[0121] In general formula (3), b31, b32, c31, and c32 may each independently represent an integer of 1 to 3. When b31, b32, c31, and c32 are 2 or 3, R ３３ , R ３４ , R ３５ and R ３６ are the same or different, R ３３ and R ３４ At least four of the above and R ３５ and R ３６ At least four of R may be oxygen atoms or groups represented by -OM. ３３ and R ３４ The number of oxygen atoms or OM groups in R may be an even number of 4 or more. ２３ and R ２４ All of R may be oxygen atoms or OM groups. ３５ and R ３６ The number of oxygen atoms or OM groups in R may be an even number of 4 or more. ３５ and R ３６ may all be oxygen atoms or OM groups.

[0122] R ３１ From R ３６ Each of the above-described R １１ From R １４ For example, R ３１ From R ３６each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. ３１ From R ３６ Each of R can be determined so that the compound represented by general formula (3) has symmetry. ３１ From R ３６ may be determined so that the compound represented by general formula (3) has an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0123] [General formula (4)] In the general formula (4), R ４１ , R ４３ and R ４４ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ４１ , R ４３ and R ４４ may be linked to each other to form a ring represented by -OMO- (R １４ is R ４１ R contained in the benzene ring to which ４３ The ring represented by -OMO- may have the same structure as -OMO- described above for general formula (1).

[0124] L is a k-valent linker containing a direct bond, an aromatic group, a double bond, or a triple bond. k is an integer of 2 or greater. The linker may be an organic group containing an arylene group, a heterocyclic group, an alkenylene group, or an alkynylene group. When k is 2, the linker may be a phenylene group, an ethene-1,2-diyl group, or an acetylene-1,2-diyl group. When k is 3 or greater, the linker may be, for example, a linker containing a benzene ring, a triazine-2,4,6-triyl group, or a linker containing a phenazine structure. When k is 3 or greater, if the linker has a structure containing a nitrogen atom, such as a triazine or phenazine structure, steric hindrance is reduced and the active material becomes a highly planar molecule, improving crystallinity and thereby further suppressing dissolution of the active material in the electrolyte.

[0125] Double lines, shown as solid and dashed lines, indicate single or double bonds. The single and double bonds may be arranged such that the compounds are conjugated molecules and have resonance structures.

[0126] In the general formula (4), a4 represents the number of repeating units of the phenazine structure described in the square brackets, and may be an integer of 1 to 5.

[0127] In general formula (4), b4 and c4 may each independently represent an integer of 1 to 3. When b4 and c4 are 2 or 3, R ４３ and R ４４ are the same or different, R ４３ and R ４４ At least four of R may be oxygen atoms or groups represented by -OM. ４３ and R ４４ The number of oxygen atoms or OM groups in R may be an even number of 4 or more. ４３ and R ４４ may all be oxygen atoms or OM groups.

[0128] R ４１ , R ４３ and R ４４ Each of the above-described R １１ From R １４ For example, R ４１ , R ４３ and R ４４ each independently represents an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. ４１ , R ４３ and R ４４ Each of R can be determined so that the compound represented by general formula (4) has symmetry. ４１ , R ４３ and R ４４ may be determined so that the compound represented by general formula (4) has an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0129] In this embodiment, the compound represented by the general formula (4) may have symmetry. For example, the compound represented by the general formula (4) may have an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0130] The above general formula (1) may be represented by the following general formula (5): [General formula (5)] In the general formula (5), R １０１ , R at the end １０２ , R １０３ ~R １０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R １０１ ~R １０８が They may be linked together to form a ring represented by -OMO-. A double line represented by a solid line and a dashed line indicates a single bond or a double bond. R １０３ ~R １０８ At least four of R may be oxygen atoms or groups represented by -OM. １０３ ~R １０８ The number of oxygen atoms or OM groups in R may be an even number of 4 or more. １０３ ~R １０８ All of R may be oxygen atoms or OM groups. １０１ ~R １０８ Each of the above-described R １１ From R １４ It may have a similar configuration.

[0131] In the general formula (5), a1 represents the number of repeating units of the phenazine structure, and may be an integer of 2 to 10.

[0132] In this embodiment, the compound represented by the general formula (5) may have symmetry. For example, the compound represented by the general formula (5) may have an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0133] The above general formula (2) may be represented by the following general formula (6): [General formula (6)] In the general formula (6), R ２０１ , R at the end ２０２ , R ２０３ ~R ２０８may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ２０１ ~R ２０８ may be linked to each other to form a ring represented by -OMO-. L is a divalent linker containing a direct bond, an aromatic group, a double bond, or a triple bond, and may have the same structure as the linker of general formula (1) described above. The double line shown by a solid line and a dashed line indicates a single bond or a double bond. R ２０３ ~R ２０８ At least four of R may be oxygen atoms or groups represented by -OM. ２０１ ~R ２０８ Each of the above-described R １１ From R １４ It may have a similar configuration.

[0134] In general formula (6), a2 represents the number of repeating units composed of a phenazine structure and a linker contained in the oligomer. a2 may be an integer from 2 to 10. When a2 is within this range, dissolution of the active material in the electrolyte during charge and discharge can be suppressed, thereby improving the cycle performance of the secondary battery. In addition, a decrease in the crystallinity of the active material and a decrease in electronic conductivity can be suppressed.

[0135] In this embodiment, the compound represented by the general formula (6) may have symmetry. For example, the compound represented by the general formula (6) may have an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0136] The above general formula (3) may be represented by the following general formula (7): [General formula (7)] In the general formula (7), R ３０１ , R at the end ３０２ , R ３０３ ~R ３１４ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ３０１ ~R ３１４may be linked to each other to form a ring represented by -OMO-. L is a divalent linker containing a direct bond, an aromatic group, a double bond, or a triple bond, and may have the same structure as the linker of general formula (1) described above. The double line shown by a solid line and a dashed line indicates a single bond or a double bond. R ３０３ ~R ３０８ At least four of the above and R ３０９ ~R ３１４ At least four of R may be oxygen atoms or groups represented by -OM. ３０１ ~R ３１４ Each of the above-described R １１ From R １４ It may have a similar configuration.

[0137] In general formula (7), a3 represents the number of repeating units of the phenazine structure bonded via a linker. a3 may be an integer from 1 to 5. When a3 is within this range, dissolution of the active material in the electrolyte during charge and discharge can be suppressed, improving the cycle performance of the secondary battery. In addition, a decrease in the crystallinity of the active material and a decrease in electronic conductivity can be suppressed.

[0138] In this embodiment, the compound represented by the general formula (7) may have symmetry. For example, the compound represented by the general formula (7) may have an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0139] The above general formula (4) may be represented by the following general formula (8): [General formula (8)] In the general formula (8), R ４０１ , R ４０３ ~R ４０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ４０１ and R ４０３ ~R ４０８may be linked to each other to form a ring represented by -OMO-. L is a k-valent linker containing a direct bond, an aromatic group, a double bond, or a triple bond, and may have the same structure as the linker of general formula (4) above. k is an integer of 2 or more. A double line represented by a solid line and a dashed line indicates a single bond or a double bond. R ４０３ ~R ４０８ At least four of the may be oxygen atoms or groups represented by -OM.

[0140] In general formula (8), a4 represents the number of repeating units of the phenazine structure. a4 may be an integer of 1 to 5. When a4 is within this range, dissolution of the active material into the electrolyte during charge and discharge can be suppressed, improving the cycle performance of the secondary battery. In addition, a decrease in the crystallinity of the active material and a decrease in electronic conductivity can be suppressed.

[0141] In the above general formulas (1) to (8), L is a direct bond or a divalent or higher linker containing an aromatic group, a double bond, or a triple bond. The linker may be an organic group containing an arylene group, a heterocyclic group, an alkenylene group, or an alkynylene group. The arylene group may be, for example, a phenylene group. The heterocyclic group may include, for example, a phenazine structure.

[0142] In the general formula (4), an example in which L contains a phenazine structure is shown in the general formula (9). [General formula (9)] In the general formula (9), R ５０１ , R at the end ５０２ , R ５０３ ~R ５０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. M may represent a hydrogen atom, or a monovalent or divalent metal atom. When M is a divalent metal atom, two adjacent R ５０１ ~R ５０８ may be linked to each other to form a ring represented by -OMO-. A double line represented by a solid line and a dashed line indicates a single bond or a double bond. In general formula (9), by including a phenazine structure in the linker, the planarity of an active material containing a plurality of phenazine structures is improved, thereby improving the crystallinity of the active material and further suppressing its dissolution in an electrolyte solution.

[0143] In general formula (9), a51 and a53 may each independently represent an integer of 1 to 5. b51, b52, b53, c51, c52, and c53 may each independently represent an integer of 1 to 3. When b51, b53, c51, and c53 are 2 or 3, the number of R ５０３ , R ５０４ , R ５０７ and R ５０８ are the same or different, R ５０３ and R ５０４ At least four of the above and R ５０７ and R ５０８ At least four of may be oxygen atoms or groups represented by -OM. n and m may each be an integer of 1 to 3. The sum of n and b52, and the sum of m and c52 may each be 4 or less.

[0144] R ５０１ From R ５０８ Each of the above-described R １１ From R １４ For example, R ５０１ From R ５０８ may each independently represent an oxygen atom, a group represented by -OM, a hydrogen atom, or an organic group. ５０１ From R ５０８ Each of R can be determined so that the compound represented by general formula (9) has symmetry. ５０１ From R ５０８ may be determined so that the compound represented by general formula (9) has an axis of symmetry, a plane of symmetry, or a center of symmetry.

[0145] [Specific Examples of Compounds Used as Active Materials] In one embodiment, the following compounds are exemplified as specific examples of the active materials.

[0146] The following compounds (1) to (5) correspond to a fully charged state of the active material. The following compounds may be examples of fully oxidized forms of the compounds represented by general formulas (1) to (9). Note that the following compounds are conjugated molecules and have resonance structures. The compounds represented by general formulas (1) to (9) above are not limited to these. Other specific examples include fully reduced or partially reduced forms of the following compounds.

[0147] [Example of a completely oxidized product] [Compound (1)] [Compound (2)] [Compound (3)] [Compound (4)] [Compound (5)]

[0148] The following compounds (6) to (10) correspond to a fully discharged state of the active material. The following compounds (6) to (10) may be examples of fully reduced forms of the compounds represented by general formulas (1) to (9). The following compounds may be fully reduced forms of the above-mentioned compounds exemplified as compounds corresponding to a fully charged state of the active material. Note that the following compounds are conjugated molecules and have resonance structures.

[0149] [An example of a completely reduced compound] [Compound (6)] [Compound (7)] [Compound (8)] [Compound (9)] [Compound (10)]

[0150] [Method for Producing Active Material] The active material is a known compound or can be synthesized by employing a known reaction.

[0151] Synthesis Example 1 Compound (1), a dimeric oligomer of phenazine tetrone, and compound (2), a trimeric oligomer of phenazine tetrone, can be synthesized according to the following reaction formula (1).

[0152] [Reaction formula (1)]

[0153] 87.0 mg (0.20 mmol) of tetraethoxyphenazine bromide, 51.4 mg (0.10 mmol) of tetraethoxyphenazine dibromide, 63.5 mg (0.25 mmol) of bis(pinacolato)diboron, 12.5 mol% palladium(0) catalyst, and cesium salt were added to a 100 mL vial. 5 mL of xylene was added thereto, and argon gas was injected and the vial was sealed. After stirring at 135°C for 24 hours, the solvent was distilled off from the reaction solution to obtain a yellow solid, which was dissolved in dichloromethane and crudely purified using a silica gel column to obtain a mixture of dimeric and trimeric oligomers in which tetraethoxyphenazine units were directly bonded. Tetraethoxyphenazine dimer and trimer were separated from the oligomer mixture by gel permeation chromatography (GPC) and separated into 50 mL vials. Mass spectrometry: 711 ([M(C ４０ H ４６ N ４ O ８ ) + H] ＋ ), 1065([M(C ６０ H ６８ N ６ O １２ ) + H] ＋ ).

[0154] Next, the isolated tetraethoxyphenazine dimer was added to a 25 wt % 1,2-dichloroethane solution containing 71.1 mg (0.100 mmol) and 500 mg of boron tribromide (2.0 mmol), and the mixture was heated and stirred at 80°C for 18 hours. After the reaction, pure water was added to the solution to precipitate a purple-brown solid. The precipitated solid was collected by filtration and washed with water. The resulting solid was suspended in 10 mL of acetonitrile in a 50 mL vial, and 2 mL of an aqueous solution containing 658 mg (1.20 mmol) of CAN was added dropwise. The mixture was heated and stirred at 40°C for 1 hour. The resulting brown precipitate was collected by filtration and washed with water and methanol. The brown precipitate was then air-dried to obtain a brown powder of phenazine tetrone dimer. Phenazine tetrone trimer was also synthesized using a similar method.

[0155] Synthesis Example 2 The p-phenylenephenazine dimer oligomer in the above compound (4) can be synthesized according to the following reaction formula (2).

[0156] [Reaction formula (2)]

[0157] 218 mg (0.5 mmol) of tetraethoxyphenazine bromide, 80.7 mg (0.2 mmol) of 1,4-bis(trimethylstannyl)benzene, and 10 mol% palladium(0) catalyst were added to a 100 mL vial. This was dissolved in 20 mL of 1,4-dioxane, and argon gas was injected into the vial, which was then sealed. After heating and stirring at 85°C for 72 hours, the mixture was cooled to room temperature, and the resulting yellow solid was filtered. The filtered solid was washed with ethyl acetate and purified by column purification using silica gel, yielding the phenylene dimer of tetraethoxyphenazine as a yellow solid. Mass spectrometry: 787 ([M(C ４６ H ５０ N ４ O ８ ) + H] ＋ ).

[0158] Of the yellow solid obtained above, 78.7 mg (0.10 mmol) was added to a 100 mL vial and suspended in 10 mL of acetonitrile. The suspension was stirred at room temperature, and 2 mL of an aqueous solution containing 658 mg (1.2 mmol) of ammonium hexanitratocerate (IV) (hereinafter referred to as CAN) was added dropwise, followed by stirring at room temperature for 2 hours. The yellow-brown precipitate formed in the solution was collected by filtration and washed with water and methanol. After air-drying, the phenylene dimer of phenazine tetrone was obtained as a brown solid.

[0159] R2032 coin type batteries were fabricated using, as the positive electrode active material, the phenazines synthesized in the above Synthesis Examples 1 and 2. The R2032 coin type batteries were fabricated according to the following procedure.

[0160] First, a phenazine as a positive electrode active material, acetylene black (manufactured by Denka Co., Ltd.) as a conductive additive, and PTFE (manufactured by Daikin Industries, Ltd.) as a binder were mixed in a ratio of positive electrode active material:conductive additive:binder = 4:5:1 (mass ratio) to prepare a positive electrode active material sheet having a diameter of approximately 10 mm and a thickness of approximately 100 μm. The positive electrode active material sheet was then pressure-bonded to a stainless steel mesh (manufactured by Hosen Co., Ltd., SUS316L) having a diameter of 14 mm and a thickness of 100 μm to prepare a positive electrode.

[0161] Next, a circular member with a diameter of 13 mm was cut out from a 0.5 mm thick lithium metal foil (manufactured by Honjo Metals Co., Ltd., purity 99.8% or more). The member cut out from the lithium foil was pressed onto a 15.5 mm diameter and 0.5 mm thick stainless steel plate (manufactured by Hosen Co., Ltd.) to prepare a negative electrode.

[0162] A glass filter (manufactured by Advantech Co., Ltd.) with a diameter of 16 mm and a thickness of 0.4 mm was prepared as a separator. ６ A non-aqueous electrolyte solution (manufactured by Kishida Chemical Co., Ltd.) containing a mixture of ethylene carbonate and diethyl carbonate was prepared. The positive electrode, separator, negative electrode, and electrolyte solution were placed inside a battery case conforming to the R2032 coin battery standard to prepare a test coin battery.

[0163] The prepared test coin-type battery was charged to 1.2-3.5 V (vs. Li) at a current density of 20 mA / g in an atmosphere of 30°C. Ｃ．Ｅ． ) or 1.0-4.2V (vs. Li Ｃ．Ｅ． ) charge / discharge tests were performed in the voltage range.

[0164] FIG. 3 shows the change in capacity retention rate during a charge-discharge test of the secondary battery of this embodiment. FIG. 3 shows the change in capacity retention rate over cycles for secondary batteries fabricated using the dimeric oligomer of phenazine tetrone (compound (1)), the trimer oligomer of phenazine tetrone (compound (2)), and, as a comparative example, the monomer of phenazine tetrone as the positive electrode active material. The discharge capacity at the first cycle was high, at 363 mAh / g when the dimeric oligomer of phenazine tetrone was used, and at 442 mAh / g when the trimer oligomer of phenazine tetrone was used. At the second cycle of the charge-discharge test, the capacity retention rates of the secondary batteries using the dimeric oligomer and the trimer oligomer were higher than those of the secondary battery using the monomer. The capacity after 10 cycles was 159 mAh / g for the dimer oligomer and 203 mAh / g for the trimer oligomer, demonstrating a higher discharge capacity than the monomer. The capacity retention after 10 cycles was 44% for the dimer oligomer and 46% for the trimer oligomer, demonstrating a higher capacity retention than the monomer. Therefore, a secondary battery containing an oligomer in which multiple phenazine structures are bonded as an active material can maintain a higher capacity retention rate than a monomeric phenazine. By using the active material for a secondary battery of this embodiment as an active material, a secondary battery can be provided that can store a large amount of charge per unit mass and has improved cycle performance.

[0165] FIG. 4 shows the change in capacity retention rate over time during a charge-discharge test of the secondary battery of this embodiment. FIG. 4 also shows the change in capacity retention rate over time over cycles for secondary batteries fabricated using the p-phenylenephenazine dimer oligomer of compound (4) and, as a comparative example, phenazine tetrone monomer as active materials. The secondary battery using the p-phenylenephenazine dimer oligomer exhibited a high discharge capacity of 439 mAh / g at the first cycle. Furthermore, the secondary battery using the p-phenylenephenazine dimer oligomer exhibited a smaller capacity decrease over cycles than the battery using the phenazine tetrone monomer, and exhibited a higher capacity retention rate at the second cycle than the battery using the phenazine tetrone monomer. The battery using the p-phenylenephenazine dimer oligomer exhibited a discharge capacity of 126 mAh / g after 10 cycles, with a capacity retention rate of 29%. On the other hand, with the phenazine tetrone monomer, the discharge capacity after 10 cycles was 112 mAh / g, and the capacity retention rate was 22%. Therefore, a secondary battery containing an oligomer in which multiple phenazine structures are linked via linkers as an active material can maintain a higher capacity retention rate than a monomeric phenazine. By using the active material for a secondary battery of this embodiment as an active material, a secondary battery can be provided that can store a large amount of charge per unit mass and has improved cycle performance.

[0166] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0167] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order.

[0168] 100 Aircraft, 110 Storage battery, 112 Storage cell, 120 Power control circuit, 130 Motor, 140 Propeller, 150 Sensor, 160 Control device, 212 Positive electrode case, 214 Negative electrode case, 216 Sealant, 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 secondary battery active material used as an active material for a secondary battery, the active material containing at least one compound represented by the following general formula (1), general formula (2), general formula (3) or general formula (4) or a salt thereof. [General formula (1)] In the general formula (1), R １１ , R at the end １２ , R １３ and R １４ 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; when M is a divalent metal atom, two adjacent R １１ ~R １４ are linked to each other to form a ring represented by -OMO-; a double line represented by a solid line and a dashed line represents a single bond or a double bond; a1 represents an integer of 2 to 10, and b1 and c1 each independently represent an integer of 1 to 3; when b1 and c1 are 2 or 3, R １３ and R １４ are the same or different, R １３ and R １４ At least four of the formulas are oxygen atoms or groups represented by -OM, In the general formula (2), R ２１ , R at the end ２２ , R ２３ and R ２４ 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; when M is a divalent metal atom, two adjacent R ２１ ~R ２４ are linked together to form a ring represented by -OMO-; L is a divalent linker including a direct bond, an aromatic group, a double bond, or a triple bond; a double line represented by a solid line and a dashed line represents a single bond or a double bond; a2 is an integer from 2 to 10, b2 and c2 are each independently an integer from 1 to 3; and when b2 and c2 are 2 or 3, R ２３ and R ２４ are the same or different, R ２３ and R ２４ At least four of the formulas are oxygen atoms or groups represented by -OM, In the general formula (3), R ３１ , R at the end ３２ , R ３３ ~R ３６ 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; when M is a divalent metal atom, two adjacent R ３１ ~R ３６ are linked together to form a ring represented by -OMO-; L is a divalent linker including a direct bond, an aromatic group, a double bond, or a triple bond; a double line represented by a solid line and a dashed line represents a single bond or a double bond; a3 is an integer of 1 to 5; b31, b32, c31, and c32 are each independently an integer of 1 to 3; and when b31, b32, c31, and c32 are 2 or 3, R ３３ , R ３４ , R ３５ and R ３６ are the same or different, R ３３ and R ３４ At least four of the above and R ３５ and R ３６ At least four of the formulas are oxygen atoms or groups represented by -OM, In the general formula (4), R ４１ , R ４３ and R ４４ 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; when M is a divalent metal atom, two adjacent R ４１ , R ４３ and R ４４ are linked together to form a ring represented by -OMO-; L is a k-valent linker including a direct bond, an aromatic group, a double bond, or a triple bond; a double line represented by a solid line and a dashed line represents a single bond or a double bond; a4 is an integer of 1 to 5, b4 and c4 are each independently an integer of 1 to 3; and when b4 and c4 are 2 or 3, R ４３ and R ４４ are the same or different, R ４３ and R ４４ At least four of the above are oxygen atoms or groups represented by -OM, and k is an integer of 2 or more.

2. The active material for a secondary battery according to claim 1, wherein the compound is a compound represented by the following general formula (5) to general formula (8): [General formula (5)] In the general formula (5), R １０１ , R at the end １０２ , R １０３ ~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; when M is a divalent metal atom, two adjacent R １０１ ~R １０８が are linked together to form a ring represented by -OMO-; a solid line and a dashed double line represent a single bond or a double bond; R １０３ ~R １０８ at least four of the formulas are oxygen atoms or groups represented by -OM, a1 is an integer of 2 to 10, [general formula (6)] In the general formula (6), R ２０１ , R at the end ２０２ , R ２０３ ~R ２０８ 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; when M is a divalent metal atom, two adjacent R ２０１ ~R ２０８ are linked together to form a ring represented by -OMO-; L is a direct bond or a divalent linker containing an aromatic group, a double bond or a triple bond; the double line represented by a solid line and a dashed line represents a single bond or a double bond; R ２０３ ~R ２０８ at least four of the formulas are oxygen atoms or groups represented by -OM, a2 is an integer of 2 to 10, [general formula (7)] In the general formula (7), R ３０１ , R at the end ３０２ , R ３０３ ~R ３１４ 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; when M is a divalent metal atom, two adjacent R ３０１ ~R ３１４ are linked together to form a ring represented by -OMO-; L is a direct bond or a divalent linker containing an aromatic group, a double bond or a triple bond; the double line represented by a solid line and a dashed line represents a single bond or a double bond; R ３０３ ~R ３０８ At least four of the above and R ３０９ ~R ３１４ at least four of the formulas are an oxygen atom or a group represented by -OM, a3 is an integer of 1 to 5, In the general formula (8), R ４０１ , R ４０３ ~R ４０８ 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; when M is a divalent metal atom, two adjacent R ４０１ and R ４０３ ~R ４０８ are linked together to form a ring represented by -OMO-; L is a k-valent linker including a direct bond, an aromatic group, a double bond, or a triple bond; the double line represented by a solid line and a dashed line represents a single bond or a double bond; R ４０３ ~R ４０８ At least four of the above are oxygen atoms or groups represented by -OM, a4 is an integer of 1 to 5, and k is an integer of 2 or more.

3. The active material for a secondary battery according to claim 1, wherein the compound is a compound represented by the following general formula (9): [General formula (9)] In the general formula (9), R ５０１ , R at the end ５０２ , R ５０３ ~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; 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-; a double line represented by a solid line and a dashed line represents a single bond or a double bond; a51 and a53 each independently represent an integer of 1 to 5; b51, b52, b53, c51, c52 and c53 each independently represent an integer of 1 to 3; when b51, b53, c51 and c53 are 2 or 3, R ５０３ , R ５０４ , R ５０７ and R ５０８ are the same or different, R ５０３ and R ５０４ At least four of the above and R ５０７ and R ５０８ at least four of are oxygen atoms or groups represented by -OM; n and m are each an integer of 1 to 3; and the sum of n and b52, and the sum of m and c52 are each 4 or less.

4. The active material for a secondary battery according to claim 1, wherein the compound has symmetry.

5. The active material for a secondary battery according to any one of claims 1, 2 and 4, wherein L is a direct bond or an organic group containing an arylene group, a heterocyclic group, an alkenylene group or an alkynylene group.

6. The compound is 2. The active material for a secondary battery according to claim 1, wherein the active material is at least any one of the above, or a completely reduced product or a partially reduced product thereof.

7. The active material for a secondary battery according to any one of claims 1 to 6, wherein M is H, Li, Na, K, Mg or Ca.

8. An electrode for a secondary battery, comprising the active material for a secondary battery according to any one of claims 1 to 7.

9. A secondary battery comprising: 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, wherein the positive electrode active material or the negative electrode active material contains the active material for secondary batteries according to any one of claims 1 to 7.

10. The secondary battery according to claim 9, wherein the positive electrode active material comprises the active material for secondary batteries according to claim 1.

11. The secondary battery according to claim 9 or 10, wherein the secondary battery is a non-aqueous secondary battery.

12. An aircraft comprising: a secondary battery according to any one of claims 9 to 11; and a thrust generating device that generates thrust by utilizing the electrical energy stored in the secondary battery.

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