JP2015130287A - Carbon complex and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon complex capable of enhancing the cycle characteristics, and to provide a power storage device.SOLUTION: When the whole is 100 mass%, a carbon complex is composed of 0-1 mass% of Zn, a metal-based material selected from a metal that is electrochemically reactive to one of an alkaline metal and an alkaline-earth metal, a transition metal, their alloys, and their composite oxides, and the reminder of carbon. When measuring the pore distribution, the volume occupied by pores having a pore size of 10-60 nm is 40 vol% or more. A power storage device uses the inventive carbon complex.

Description

  The present invention relates to a carbon composite and an electricity storage device using the same.

  With the widespread use of electronic devices such as notebook computers, mobile phones, and digital cameras, the demand for secondary batteries for driving these electronic devices is increasing. In recent years, these electronic devices have been required to increase the capacity of secondary batteries because power consumption has increased with the progress of higher functionality and miniaturization is expected. Among secondary batteries, non-aqueous electrolyte secondary batteries (particularly lithium ion secondary batteries) can be increased in capacity, and thus are being used in various electronic devices. In addition, development of an air secondary battery is also underway as a secondary battery capable of increasing the capacity.

  A non-aqueous electrolyte secondary battery generally has a positive electrode in which a positive electrode active material layer having a positive electrode active material is formed on the surface of the positive electrode current collector, and a negative electrode active material layer having a negative electrode active material on the surface of the negative electrode current collector. The negative electrode is connected via a non-aqueous electrolyte (non-aqueous electrolyte solution) and stored in a battery case.

  An air secondary battery is a battery (secondary battery) that uses oxygen in the air as a positive electrode active material and various metals as a negative electrode active material. In air secondary batteries, the use of catalysts such as noble metals, metal oxides, and carbon materials is being promoted for the positive electrode. Studies are underway on the use of metals such as zinc, aluminum, magnesium, and lithium as the negative electrode active material.

  As a negative electrode of a nonaqueous electrolyte secondary battery (lithium ion secondary battery), particles such as tin or silicon or nanotubes are being used as a negative electrode material (negative electrode active material) capable of realizing a high capacity. Specifically, copper-coated silicon, carbon-coated silicon, and the like have been studied. Strictly speaking, silicon belongs to a semiconductor, but also exhibits a semi-metallic property, and therefore is treated as a metal in the present application.

However, silicon (metal) is known to have a very large volume expansion when lithium is absorbed. When this large volume expansion is repeated, there is a problem that the metal is broken apart. When the metal is broken, the number of broken pieces that are not in electrical contact with the electrode (negative electrode current collector) increases, and the battery capacity of the secondary battery is greatly reduced.
In order to solve such a problem, Patent Documents 1 and 2 disclose a technique for supporting a metal on a porous carbon material.

  Patent Document 1 discloses a technique in which a metal capable of forming an alloy with lithium, for example, an active material such as tin, calcium, strontium, barium, or iridium, is supported in micropores of activated carbon.

  Patent Document 2 manufactures a metal-supported nanostructure in which a metal capable of occluding lithium is supported in a carbon material having a three-dimensional continuous structure in which a region surrounded by a graphene multilayer film is an alveolar hole. Techniques to do this are disclosed. In Patent Document 2, by supporting metal particles in a state of inclusion in a carbon material having pores, electrical contact can be maintained even if the volume of the metal particles changes or even destruction occurs.

Patent No. 4069465 JP 2012-56833 A

  However, in Patent Document 1, there is a problem that the upper limit of the mass of carbon constituting the activated carbon is 30% due to the addition amount of the active material described above, and a sufficient capacity retention rate cannot be obtained. This also indicates that the lithium ion secondary battery cannot obtain sufficient charge / discharge efficiency as a result.

  Moreover, in patent document 2, there existed a problem that the effect of the improvement of the charging / discharging efficiency of a lithium ion secondary battery became limited. Further, the metal-supported nanostructure described in the cited document 2 has a problem that it is limited only to the use of the lithium ion secondary battery.

  The present invention has been made in view of the above circumstances, and it is an object to provide a carbon composite capable of improving cycle characteristics when used in a secondary battery (power storage device) and a power storage device using the same. And

  In order to solve the above-mentioned problems, the present inventors have studied the carbon composite, and as a result, have come to make the present invention.

  The carbon composite of the present invention is a metal that can electrochemically react with zinc of greater than 0 mass% and less than 1 mass%, and at least one of an alkali metal and an alkaline earth metal, when the total is 100 mass%. , Transition metals, alloys thereof, metal materials selected from these composite oxides, and the balance carbon, and the pore diameter is 10 to 60 nm when pore distribution is measured. The volume occupied by the pores is 40 vol% or more.

  The carbon composite of the present invention is configured to have a predetermined amount of zinc and a metal-based material. Thereby, a metal-type material can advance an electrochemical reaction over a long period of time. That is, when the ions such as lithium ions are used for an electricity storage device that takes charge of electric capacity, it is possible to suppress a decrease in cycle characteristics.

  It is preferable that carbon forms a porous carbon substrate, and zinc and metal-based material are supported on the surface of the porous carbon substrate, and zinc and metal-based material are supported in the pores of the porous carbon substrate. More preferably.

  Since zinc and a metal-type material are carry | supported by the porous carbon base material, each of zinc and a metal-type material will be in the exposed state, and can show the effect of carrying more reliably. In addition, because zinc and metal-based material are supported in the pores of the porous carbon base material, even if the metal-based material undergoes an electrochemical reaction and expands, the amount of expansion by the pores Is restricted, and the destruction of the metal-based material is suppressed.

  The metal material preferably contains at least one of Sn and Si at 20 mass% or more and 60 mass% or less. The carbon composite of the present invention is preferably used for a lithium ion secondary battery. Sn and Si are known as negative electrode active materials capable of obtaining a large battery capacity in lithium ion secondary batteries, and when used in lithium ion secondary batteries by selecting a metal-based material from these in a predetermined amount. Especially effective.

  The metal-based material is a metal of V, Cr, Mn, Fe, Co, Ni, Mo, Ru, Pd, Ag, Pt, or Au, an alloy containing the metal, a composite oxide containing the metal, or a metal phthalocyanine. One type is preferred. The carbon composite of the present invention is preferably used for a lithium air secondary battery. It is known that these metals can be used for the positive electrode of a lithium air secondary battery, and by selecting a metal-based material from these, the effect can be exhibited particularly when used for a lithium air secondary battery.

The electricity storage device of the present invention is characterized in that the carbon composite according to any one of claims 1 to 7 is used as an electrode, and lithium ions bear electric capacity.
It is preferable that it is a lithium ion secondary battery which used the carbon composite_body | complex of any one of Claims 1-5 for the negative electrode.
It is preferable that it is a lithium air secondary battery using the carbon composite of any one of Claims 1-3 and 6-7 for the positive electrode.

  Since the electricity storage device of the present invention is formed using the above-described carbon composite, the above-described effects are exhibited.

FIG. 3 is a diagram showing a derivation result of a radial distribution function of the carbon composite of Example 1. 2 is a TEM photograph of the carbon composite of Example 1. 3 is a cross-sectional view of a main part showing a configuration of a lithium-air secondary battery of Example 2. FIG.

[First embodiment]
A first embodiment of the present invention will be described using a negative electrode active material (carbon composite) of a lithium ion secondary battery and a lithium ion secondary battery (storage device) using the same.
The lithium ion secondary battery of this embodiment is an electricity storage device in which lithium ions bear electric capacity, and includes a positive electrode, a negative electrode, and a nonaqueous electrolyte.

(Negative electrode)
The negative electrode has the carbon composite of the present invention as a negative electrode active material.

(Carbon composite)
The carbon composite is a metal or transition metal that can electrochemically react with zinc of greater than 0 mass% and less than 1 mass%, and at least one of an alkali metal and an alkaline earth metal, when the total is 100 mass%. , These alloys, metal materials selected from these composite oxides, and the balance carbon. And when the pore distribution is measured, the volume occupied by pores having a pore diameter of 10 to 60 nm is 40 vol% or more.
When the carbon composite of the present invention is made of zinc, a metal-based material, and carbon, it becomes a negative electrode active material having excellent cycle characteristics.

  The metal material is a metal selected from metals capable of electrochemically reacting with at least one of alkali metals and alkaline earth metals, transition metals, alloys thereof, and composite oxides thereof. This metal material causes an electrochemical reaction with an alkali metal (lithium ion), so that the metal material has a battery capacity and functions as a negative electrode active material.

  The metal-based material preferably contains at least one of Sn and Si at 20 mass% or more and 60 mass% or less (20 to 60 mass%). The content ratio of at least one of Sn and Si is a ratio when the entire carbon composite is 100 mass%.

  Sn and Si are metals that can adsorb and desorb a large amount of lithium ions, and are metals that can obtain a large battery capacity when used as a negative electrode active material of a lithium ion secondary battery.

  And by containing at least one of these at 20-60 mass%, it becomes possible for the lithium ion secondary battery of this form to have a large battery capacity. When the content ratio is less than 20 mass%, the ratio of the negative electrode active material exhibiting a high capacity decreases, and the effect of improving the battery capacity of the lithium ion secondary battery cannot be sufficiently obtained. If it exceeds 60 mass%, the ratio of at least one of Sn and Si (metal material) becomes too large. In particular, as described later, when carbon forms a porous carbon substrate and is supported in the pores, the proportion of the carbon supported outside the pores increases.

  Zinc suppresses damage to metallic materials. Specifically, expansion occurs when the metal-based material occludes lithium ions, but zinc restricts this expansion from becoming excessive. As a result, destruction of the metal-based material can be suppressed. Moreover, zinc bears the electrical conductivity of the broken piece of the metallic material when the metallic material is broken. As a result, a decrease in battery capacity is suppressed.

  Zinc is larger than 0 mass% and is contained in 1 mass% or less, that is, 0 to 1 mass% (1 mass% or less). When zinc exceeds 1 mass%, the amount of metal-based material supported decreases, leading to a decrease in battery capacity of the lithium ion secondary battery. In particular, as described later, when carbon forms a porous carbon base material and is supported in the pores, excessive zinc will block the pores, and the battery capacity of the lithium ion secondary battery may be reduced. More likely to occur.

  Carbon constitutes the balance other than zinc and metal-based materials. The carbon composite of the present invention carries zinc and a metal-based material. Carbon also functions as a conductive material responsible for the conduction of electricity from the metal-based material as the negative electrode active material.

  Preferably, carbon forms a porous carbon substrate, and zinc and a metal-based material are supported on the surface of the porous carbon substrate. Since the carbon forms a porous carbon base material, the carbon composite of the present invention in which zinc and a metal-based material are supported can obtain a large surface area and can support more zinc and a metal-based material. . In particular, the amount of metal-based material supported can be increased, which can contribute to an increase in battery capacity.

  Zinc and a metal-based material are preferably supported in the pores of the porous carbon substrate. Zinc and metal-based material are supported in the pores of the porous carbon substrate, so that even if the metal-based material undergoes an electrochemical reaction and expands, the amount of expansion is regulated by the pores. As a result, the destruction of the metal-based material is suppressed.

  Even if the metal-based material breaks down, the metal-based material is supported in the pores of the porous carbon base material. It will be in contact with the part. That is, even if the metal-based material (negative electrode active material) is broken, the conductive path is maintained, and the battery capacity can be prevented from decreasing.

  Furthermore, since zinc and a metal-based material are supported in the pores of the porous carbon base material, the movement from the inside of the pores to the outside is physically restricted, and a metal is contained in the electrolyte of the lithium secondary battery. The movement of the system material is also suppressed.

The specific structure of the porous carbon base material is not limited, but the carbon-containing rod-like body or plate-like body is three-dimensionally bonded, and in the rod-like body or plate-like body, It is preferable that alveoli-like pores defined by the graphene multilayer film wall are formed.
The porous carbon substrate preferably has a rod-like body diameter and a plate-like body width of 100 nm to 10 μm.

  As the negative electrode active material of the present embodiment, when the whole is 100 mass%, a rod-shaped body containing 0 to 1 mass% of zinc, 20 to 60 mass% of Si and Sn, and the balance being carbon, with the balance being carbon. Alternatively, the plate-like body is three-dimensionally bonded, and the rod-like body or plate-like body has fine pores of a porous carbon base material in which alveoli-like pores defined by the graphene multilayer film walls are formed. Most preferred is a carbon composite in which zinc and at least one of Si and Sn are supported in the pores.

  In the carbon composite, when the pore distribution is measured, the volume occupied by pores having a pore diameter of 10 to 60 nm is 40 vol% or more. When the pore distribution is within this range, an excellent effect can be exhibited when zinc and the metal-based material are supported in the pores of the porous carbon substrate.

  In pores having a pore diameter of less than 10 nm, zinc and metal-based material are hardly supported in the pores, and as a result, a large amount is supported outside the pores. In addition, in the case of pores larger than 60 nm, when the metal-based material supported in the pores expands, the effect of regulating the expansion cannot be sufficiently obtained. Further, the metal-based material jumps out of the pores and is electrically insulated, so that the battery reaction is easily inactivated.

When the volume occupied by the pores is 40 vol% or more, a sufficient amount of metal-based material can be supported in the pores. When the volume is less than 40 vol%, zinc and the metal-based material are hardly supported in the pores, and as a result, a large amount is supported outside the pores.
In this embodiment, the carbon composite preferably has a BET specific surface area of 80 m ² / g or more, and more preferably 300 m ² / g or more.

  The negative electrode active material of the lithium ion secondary battery of this embodiment may contain a conventionally known negative electrode active material in addition to the carbon composite. That is, a mixture of a carbon composite and a compound used as a conventionally known negative electrode active material may be used as the negative electrode active material. Examples of the conventionally known negative electrode active material include an active material made of at least one element of Li, Sb, Ge, and C.

  Among these negative electrode active materials, C is preferably a carbonaceous material capable of occluding and desorbing electrolyte ions of a lithium ion secondary battery (having Li occlusion ability), such as acetylene black, ketjen black, carbon Examples thereof include carbonaceous materials such as black, graphite, and amorphous coated graphite.

(Other configuration of negative electrode)
As long as the negative electrode of this embodiment has a carbon composite as a negative electrode active material, other configurations are not limited. In the negative electrode of this embodiment, the active material layer is formed by applying a mixture obtained by mixing a negative electrode active material and a binder to the surface of a current collector, as in the case of a conventionally known negative electrode. It is preferable.

  The negative electrode mixture is prepared by dispersing the negative electrode active material in a binder solution or further adding a solvent. As the solvent, an organic solvent used for a solution binder or an organic solvent capable of dissolving the binder can be used. Examples thereof include, but are not limited to, NMP, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran.

  The negative electrode mixture may be further mixed with a binder made of a polyacrylic acid compound. Another binder is a conventionally known binder used for the negative electrode of a lithium ion secondary battery. For example, PTFE, PVDF, fluororesin copolymer (tetrafluoroethylene / hexafluoropropylene copolymer), SBR, acrylic rubber, fluororubber, polyvinyl alcohol (PVA), styrene / maleic resin, polyacrylic Examples thereof include acid salts and CMC.

  As the negative electrode current collector, a conventionally known current collector can be used, and a foil, mesh, or the like made of copper, stainless steel, titanium, or nickel can be used.

(Positive electrode)
As long as the positive electrode has a positive electrode active material that can release lithium ions during charging and can be occluded during discharging, other configurations are not limited. The positive electrode of the present embodiment is obtained by applying an active material layer by applying a mixture obtained by mixing a positive electrode active material, a conductive material and a binder to a current collector, as in the case of a conventionally known positive electrode. It is preferable.

  A conventionally known positive electrode active material can be used as the positive electrode active material. As the positive electrode active material, for example, various oxides, sulfides, lithium-containing oxides, conductive polymers, and the like can be used. The positive electrode active material is preferably a lithium-transition metal composite oxide.

Lithium - transition metal composite oxide is preferably a lithium metal compound polyanion structure ^{_{(Li α M 0 β X η}} O 4-γ Z γ). (Note that M ⁰ : one or more selected from Mn, Co, Ni, Fe, Cu, Cr, Mg, Ca, Zn, Ti, one or more selected from X: P, As, Si, Mo, Ge, Z: One or more selected from Al, Mg, Ca, Zn and Ti can be optionally contained, 0 ≦ α ≦ 2.0, 0 ≦ β ≦ 1.5, 1 ≦ η ≦ 1.5, 0 ≦ γ ≦ 1.5)

The lithium-transition metal composite oxide is preferably a lithium-transition metal composite oxide having an olivine structure. Examples of the olivine-structured lithium-transition metal composite oxide include LiFePO ₄ and LiFe _x Mn _1-x PO ₄ (0 ≦ x <1).

As long as the conductive material is made of a material capable of ensuring the electrical conductivity of the positive electrode, other configurations are not limited. Examples of the conductive material include fine particles of graphite, carbon black such as acetylene black, ketjen black and carbon nanofiber, and particles (fine particles) made of amorphous carbon such as needle coke.
The binder binds the positive electrode active material particles and the conductive material. Examples of the binder include PVDF, EPDM, SBR, NBR, fluorine rubber, and the like.

  The positive electrode mixture can be obtained by mixing a positive electrode active material, a conductive material, and a binder, and is prepared by dispersing a positive electrode active material or the like in a solvent. As the solvent, an organic solvent that normally dissolves the binder is used. Examples thereof include, but are not limited to, NMP, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran. In some cases, a positive electrode active material is slurried with PTFE or the like by adding a dispersant, a thickener, or the like to water.

  As the positive electrode current collector, for example, a material obtained by processing a metal such as aluminum or stainless steel, for example, a foil processed into a plate shape, a net, a punched metal, a foam metal, or the like can be used, but is not limited thereto.

(Nonaqueous electrolyte)
The non-aqueous electrolyte is not particularly limited by its material structure, and a known material structure can be used. The non-aqueous electrolyte of this embodiment (generally also referred to as a non-aqueous electrolyte) is preferably one in which a supporting salt is dissolved in an organic solvent, similarly to a conventionally known non-aqueous electrolyte.

The kind of the supporting salt of the nonaqueous electrolyte is not particularly limited. For example, the inorganic salt selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , derivatives of these inorganic salts, LiSO ₃ CF ₃ , Organic salt selected from LiC (SO ₃ CF ₃ ) ₃ and LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ) And at least one of these organic salt derivatives. These supporting salts can further improve the battery performance, and can maintain the battery performance higher even in a temperature range other than room temperature. The concentration of the supporting salt is not particularly limited, and it is preferable to select appropriately in consideration of the types of the supporting salt and the organic solvent.

The organic solvent (non-aqueous solvent) in which the supporting salt dissolves is not particularly limited as long as it is an organic solvent used in ordinary non-aqueous electrolytes. For example, carbonates, halogenated hydrocarbons, ethers, ketones , Nitriles, lactones, oxolane compounds and the like can be used. In particular, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, vinylene carbonate and the like, and mixed solvents thereof are preferable. Among these organic solvents, use of at least one non-aqueous solvent selected from the group consisting of carbonates and ethers is particularly excellent in the solubility, dielectric constant and viscosity of the supporting salt, and the lithium ion secondary battery This is preferable because the charge / discharge efficiency is increased.
In the lithium ion secondary battery of this embodiment, the most preferable non-aqueous electrolyte is a support salt dissolved in an organic solvent.

(Other configurations)
The lithium ion secondary battery of this embodiment is not particularly limited except for having a positive electrode, a negative electrode, and a nonaqueous electrolyte, and a known material structure can be used.

  For example, the lithium ion secondary battery is preferably formed by being enclosed in a case together with a nonaqueous electrolyte in a state where the positive electrode and the negative electrode are interposed via a separator. In addition to these elements, other elements as required can be included.

  The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the nonaqueous electrolyte. As the separator, for example, a porous synthetic resin film, particularly a polyolefin polymer (polyethylene, polypropylene) porous film is preferably used. Note that the separator preferably has a shape larger than that of the positive electrode and the negative electrode in order to ensure insulation between the positive electrode and the negative electrode.

  The lithium ion secondary battery preferably has other elements as necessary in addition to the above elements. The shape of the lithium ion secondary battery is not particularly limited, and can be a battery of various shapes such as a coin shape, a cylindrical shape, a square shape, or an indefinite shape sealed in a laminate outer package.

(Other forms of this form)
In this embodiment, an example in which the carbon composite of the present invention is used as a negative electrode active material of a lithium ion secondary battery has been described. However, the use of the carbon composite of the present invention is limited to only a lithium ion secondary battery. is not. For example, you may use for a conventionally well-known nonaqueous electrolyte secondary battery.

[Second Embodiment]
A second embodiment of the present invention will be described using a catalyst for a positive electrode of a lithium air secondary battery and a lithium air secondary battery (electric storage device) using the same.
The lithium-air secondary battery of this embodiment is an electricity storage device in which oxygen and lithium ions have electric capacity, and includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. Lithium-air batteries consist of a reaction that takes oxygen and reacts with lithium ions during discharge to generate and store lithium oxide on the positive electrode side, and conversely decomposes lithium oxide into lithium ions and oxygen during charging.

(Positive electrode)
The positive electrode includes a catalyst and a conductive material. The positive electrode advances the battery reaction by reacting oxygen and lithium ions.

(Carbon composite)
In this embodiment, the carbon composite of the present invention is used as a catalyst and a conductive material. The zinc of the carbon composite and the metal-based material function as a catalyst for the air secondary battery. The surface of the carbon composite becomes a charge / discharge reaction field of the air battery. The carbon, carbon, zinc, zinc oxide, and metal-based material of the carbon composite function as a catalyst for promoting the charge / discharge reaction of the air secondary battery. In addition, the surface of the carbon composite, the voids between the particles, and the pores in the particles function as a space for accumulating discharge products. In addition, the structure which does not mention especially the carbon composite_body | complex of this form can be made the same as that of 1st embodiment.

  When the total amount of the carbon composite is 100 mass%, it is electrochemically greater than 0 mass% and 1 mass% or less, that is, 0 to 1 mass% of zinc and at least one of an alkali metal and an alkaline earth metal. It consists of a metal material selected from reactive metals, transition metals, alloys thereof, composite oxides thereof, and the balance of carbon. And when the pore distribution is measured, the volume occupied by pores having a pore diameter of 10 to 60 nm is 40 vol% or more.

The metal-based material is a metal of V, Cr, Mn, Fe, Co, Ni, Mo, Ru, Pd, Ag, Pt, or Au, an alloy containing the metal, a composite oxide containing the metal, or a metal phthalocyanine. One type is preferred. These are known to be metals having particularly excellent catalytic activity. That is, the metal-based material includes V, Cr, Mn, Fe, Co, Ni, Mo, Ru, Pd, Ag, Pt, and Au, an alloy containing the metal, a composite oxide containing the metal, and metal phthalocyanines. By being at least one of these, it becomes possible to react more oxygen and lithium ions at the positive electrode.
The loading amount of the metal-based material is not limited and is preferably the same loading amount as the positive electrode catalyst of the conventional lithium-air secondary battery.

  Zinc functions as a catalyst, similar to metal-based materials. That is, zinc can react more oxygen and lithium ions at the positive electrode together with the metal-based material. In this embodiment, zinc may be not only metallic zinc but also zinc-based metals such as zinc oxide, alloys containing zinc, and composite oxides.

  Zinc is contained at 0 to 1 mass% (1 mass% or less). When zinc is contained in excess of 1 mass%, the amount of the metal-based material excellent in catalytic activity is reduced, and the space for storing lithium oxide during discharge is reduced. The capacity is reduced. In particular, as described later, when carbon forms a porous carbon base material and is supported in the pores, excess zinc will block the pores, which reduces the battery capacity of the lithium-air secondary battery. More likely to occur.

  Carbon constitutes the balance other than zinc and metal-based materials. The carbon composite of the present invention carries zinc and a metal-based material. Furthermore, lithium oxide is generated during discharge, and lithium oxide is accumulated in the pores, the spaces between the particles and on the surface to obtain a discharge capacity. Carbon also functions as a conductive material responsible for the conduction of electricity from the metal-based material as the negative electrode active material.

  Preferably, carbon forms a porous carbon substrate, and zinc and a metal-based material are supported on the surface of the porous carbon substrate. Since the carbon forms a porous carbon base material, the carbon composite of the present invention in which zinc and a metal-based material are supported can obtain a large surface area and can support more zinc and a metal-based material. . In particular, the amount of metal-based material supported can be increased, which can contribute to an increase in battery capacity.

  Zinc and a metal-based material are preferably supported in the pores of the porous carbon substrate. Zinc and metal-based materials are supported in the pores of the porous carbon substrate, so that the entire surface area of the porous carbon substrate can be used, and the reaction between oxygen and lithium ions is increased. Can do.

  The specific structure of the porous carbon base material is not limited, but the carbon-containing rod-like body or plate-like body is three-dimensionally bonded, and in the rod-like body or plate-like body, It is preferable that alveoli-like pores defined by the graphene multilayer film wall are formed.

  In the carbon composite, when the pore distribution is measured, the volume occupied by pores having a pore diameter of 10 to 60 nm is 40 vol% or more. When the pore distribution is within this range, an excellent effect can be exhibited when zinc and the metal-based material are supported in the pores of the porous carbon substrate.

  In pores having a pore diameter of less than 10 nm, zinc, metal-based materials, and lithium oxide generated during discharge are hardly supported in the pores. As a result, lithium oxide generated during discharge cannot accumulate in the pores. , Discharge capacity is reduced. On the other hand, in the case of large pores exceeding 60 nm, the size of the supported zinc and metal-based material increases, and the catalytic activity decreases. Moreover, since the size of the lithium oxide produced at the time of discharging becomes large, it becomes difficult to disassemble at the time of charging. Therefore, the capacity maintenance rate of the battery is reduced.

When the volume occupied by the pores is 40 vol% or more, a sufficient amount of metal material and lithium oxide generated during discharge can be accumulated in the pores. When the volume is less than 40 vol%, it becomes difficult for the metal-based material and lithium oxide generated during discharge to be accumulated in the pores, and as a result, sufficient battery capacity cannot be obtained.
The positive electrode of the lithium air secondary battery of this embodiment may contain a conventionally known catalyst or conductive material in addition to the carbon composite.

  This conventionally known catalyst is, for example, selected from the group consisting of silver, platinum, iridium oxide, ruthenium oxide, manganese oxide, cobalt oxide, nickel oxide, iron oxide, copper oxide, and metal phthalocyanines. 1 type or 2 types or more can be mentioned. Furthermore, a radical material having a stable radical in the molecule may be used as a catalyst.

  The radical material is not particularly limited, but is preferably one that can stably exist in the atmosphere of the air secondary battery. Examples of the radical material include compounds having the following radical skeleton. The chemical structure of the portion other than the radical skeleton is not particularly limited as long as the radical is stable, whether it interacts electronically with the radical or does not interact with the radical. is not. For example, the radical skeleton can be bonded to some polymer compound.

  The radical skeleton was selected from the group consisting of, for example, a skeleton having a nitroxyl radical, a skeleton having an oxy radical, a skeleton having a nitrogen radical, a skeleton having a sulfur radical, a skeleton having a carbon radical, and a skeleton having a boron radical. I can give you something. Specifically, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPO-OH), 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-yloxy (3-carbamoyl-PROXYL), or 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy ( 3-carboxy-PROXYL).

  Examples of conventionally known conductive materials include acetylene black, ketjen black, carbon black, graphite, amorphous coated graphite, graphite, carbon nanotube, and carbon fiber.

(Other configuration of positive electrode)
As long as the positive electrode of this form has a carbon composite, other forms will not be limited. The positive electrode of the present embodiment should be formed by mixing a carbon composite and other additives together with a binder and press-molding the current collector, as with the positive electrode of a conventionally known lithium-air secondary battery. Is preferred.
As the current collector, one having electrical conductivity can be used. The current collector also preferably serves as an oxygen permeable membrane that supplies oxygen to the positive electrode.

  Examples of the oxygen permeable membrane include an oxygen-enriched membrane that selectively permeates oxygen and a membrane made of a general polymer material (may be used as it is or a porous membrane). As polymer materials, polyethylene, polypropylene, poly-4-methyl-1-pentene, poly-3-methyl-1-butene, polystyrene, polymethyl methacrylate, polyvinyl chloride, nylon 6, nylon 66, polyvinyl alcohol, polyethylene At least one of terephthalate, polybutylene terephthalate, polyphenylene sulfide, polytetrafluoroethylene, cellulose acetate, polysulfone, polycarbonate, and polyimide can be employed.

  When the oxygen permeable membrane also serves as a current collector, a porous material (consisting of stainless steel, nickel, aluminum, copper, etc.), mesh / punching metal, etc., formed from a conductive material that communicates with the front and back surfaces is used. be able to. When a porous material is employed, it is preferable that the pores, nets, punched metal holes, etc. are filled with a carbon composite and other additives.

  The current collector is preferably a porous body such as a mesh or mesh, in order to allow oxygen to diffuse quickly, and a porous metal plate such as stainless steel, nickel, aluminum, or copper is preferably used. The current collector may be coated with an oxidation-resistant metal or alloy film on its surface in order to suppress oxidation.

  The binder fixes the carbon composite and other additives to the current collector. The binder is not particularly limited, and examples thereof include a thermoplastic resin and a thermosetting resin. For example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin) , Polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrif Materials such as oloethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer, etc. I can give you. These materials may be used alone or in combination.

(Negative electrode)
As long as the negative electrode has a negative electrode active material capable of occluding and releasing metal ions (lithium ions) responsible for electrical conduction, other configurations are not limited. The negative electrode of this embodiment is formed by applying an active material layer by applying a mixture obtained by mixing a negative electrode active material, a binder and other additives to a current collector, similarly to a conventionally known negative electrode It is preferable that

  Negative electrode active materials include metallic lithium, lithium alloys, metal materials that can store and release lithium, and alloy materials that can store and release lithium (not only alloys consisting of metals but also alloys of metals and metalloids). The structure includes solid solution, eutectic (eutectic mixture), intermetallic compounds or compounds in which two or more of them coexist), and compounds capable of occluding and releasing lithium (carbon 1 type or 2 types or more of negative electrode materials selected from the group which consists of material etc. can also be used.

  Metal elements and metalloid elements that can constitute metal materials and alloy materials include tin (Sn), lead (Pb), aluminum (Al), indium (In), silicon (Si), zinc (Zn), and antimony (Sb). ), Bismuth (Bi), cadmium (Cd), magnesium (Mg), boron (B), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), zirconium (Zr), yttrium (Y ), Hafnium (Hf).

  Among these, a simple substance, alloy or compound of Group 4B metal element or semimetal element in the short-period type periodic table is preferable, and silicon (Si) or tin (Sn), or an alloy or compound thereof is particularly preferable. These may be crystalline or amorphous.

Examples of the anode material capable of inserting and extracting lithium further include other metal compounds such as oxide, sulfide, or lithium nitride such as LiN ₃ . Examples of the oxide include MnO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , NiS, and MoS. In addition, examples of the oxide that has a relatively low potential and can occlude and release lithium include iron oxide, ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, and tin oxide. Examples of the sulfide include NiS and MoS.

The binder has an action of connecting between the constituent elements included in the negative electrode layer and between the constituent elements and the negative electrode current collector. As the binder, an organic binder or an inorganic binder can be used, and the binder exemplified in the column of the positive electrode can be used. Desirably, PVDF, polyvinylidene chloride, PTFE are used. And compounds such as CMC.
Examples of other additives include conductive materials.

  The negative electrode mixture can be obtained by mixing a negative electrode active material and a binder, and is prepared by dispersing a negative electrode active material or the like in a solvent. As the solvent, an organic solvent that normally dissolves the binder is used. Examples thereof include, but are not limited to, NMP, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran. In some cases, a positive electrode active material is slurried with PTFE or the like by adding a dispersant, a thickener, or the like to water.

  As a negative electrode collector, copper, nickel, etc. can be made into forms, such as a net | network, a punched metal, foam metal, plate shape, foil shape, for example. A battery casing can also be used as the negative electrode current collector.

(Nonaqueous electrolyte)
As long as the nonaqueous electrolyte is a nonaqueous electrolyte capable of conducting metal ions (lithium ions) responsible for electrical conduction, other configurations are not limited. For example, a solution obtained by dissolving a supporting salt in a nonaqueous solvent can be used. The non-aqueous electrolyte may contain an ionic liquid. The nonaqueous electrolyte is interposed between the positive electrode and the negative electrode, and becomes a medium for conducting metal ions between the two.

  As the non-aqueous solvent, an aprotic organic solvent can be used. Examples of such organic solvents include cyclic carbonates, chain carbonates, cyclic esters, cyclic ethers, chain ethers, and the like. Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate, butylene carbonate, vinylene carbonate and the like. Examples of the chain carbonate include dimethyl carbonate (DMC), diethyl carbonate, and ethyl methyl carbonate (EMC). Examples of the cyclic ester carbonate include gamma butyrolactone and gamma valerolactone. Examples of the cyclic ether include tetrahydrofuran and 2-methyltetrahydrofuran. Examples of the chain ether include dimethoxyethane, ethylene glycol dimethyl ether, and ethylene glycol diethyl ether. These may be used alone or in combination.

  The ionic liquid is not particularly limited as long as it is liquid alone at the use temperature of the battery. Examples include those having one or more cations selected from the group consisting of imidazolium, pyridinium, phosphonium, ammonium, pyrrolidinium, guanidinium, isouronium, pyrazolium, sulfonium, piperidinium, and thiouronium. In particular, those having one or more cations selected from the group consisting of imidazolium, pyridinium, and pyrrolidinium are desirable. In particular, the cation includes 1-methyl-1-propylpiperidinium, 1,1,1-trimethyl-1-propylammonium, 1-methyl-1-propylpyrrolidinium, and / or 1-methyl-1-butyl. It is desirable to have pyrrolidinium.

Furthermore, ionic ^{_{liquids, B (C 2 O 4)}} 2 -, PF 6 -, BF 4 -, Cl -, I -, Br -, AlCl 4 -, HCO 3 -, CF 3 SO 3 -, NO 3 - , SO ₃ OH ⁻ , CF ₃ CO ₂ ⁻ , CH ₃ OCO ₂ ⁻ , CH ₃ OSO ₃ ⁻ , SCN ⁻ , (SO ₂ F) ₂ N ⁻ , (SO ₂ CF ₃ ) ₂ N ⁻ , (C ₂ F ^{_{5) 3 PF 3 -, CH}} 3 C 6 H 4 SO 3 -, C 8 H 16 SO 3 -, (CN) 2 N -, C 9 H 19 CO 2 -, C 4 BO 8 -, N (SO 2 ^{_{CF 3) 2 -, (CH}} 3) 2 PO 4 -, (C 2 H 5) 2 PO 4 -, C 2 H 5 OSO 3 -, C 6 H 13 OSO 3 -, C 4 F 9 SO 3 -, and _C 8 _H 17 OSO ₃ ^- 1 kind selected from the group consisting or 2 It is preferred to have a more anions. In particular, as the ^{_{anion, (SO 2 F) 2 N}} - preferably with: (bis (trifluoromethanesulfonyl) imide TFSI) - (FSI bis (fluorosulfonyl) ^{_{imide), (SO 2 CF 3)}} 2 N .

  Nonaqueous electrolytes include, among others, 1,2-dimethoxyethane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, 3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, 3-methyloxazolidinone, methyl sulfolane formate, dimethyl It is desirable to include one or more non-aqueous solvents selected from the group consisting of sulfoxide and acetonitrile.

Examples of the supporting salt include those containing metal ions (lithium ions) corresponding to metal ions that can be occluded and released by the positive and negative electrodes. In particular, M _a X _b : (X is Br, Cl, PF ₆ , BF ₄ , NO ₃ , AsF ₆ , ClO ₄ , CF ₃ SO ₃ , N (SO ₂ CF ₃ ) ₂ , and N (SO ₂ CF ₂ CF ₃₎ is selected from the group consisting of ₂ .a, b is an integer of 1 to 3), and _{Mg (AlWXYZ) 2: (W} , X, Y, Z _{are, Br, Cl, CH 3,} C 2 1 type, or 2 or more types of supporting salts selected from the group consisting of H ₅ , C ₃ H ₇ , and C ₄ H ₉ .

The concentration of the supporting salt is preferably 0.1 to 2.0 M (mol / L), more preferably 0.8 to 1.2 M, based on the whole nonaqueous electrolyte.
The air secondary battery of the present embodiment can include a separator interposed between the positive electrode and the negative electrode, a battery case that houses the positive electrode, the negative electrode, and the nonaqueous electrolyte.

  As the separator, a porous film, a nonwoven fabric, or the like that can exist stably in an atmosphere in the air secondary battery can be used. For example, a separator can be comprised from porous membranes, such as a woven fabric or nonwoven fabric which consists of glass fiber, polyolefin, polyester.

  The battery case can be formed from a material that is stable against the atmosphere in the battery. Further, as described above, a configuration that also serves as a current collector in the positive electrode and / or the negative electrode may be used, or a configuration that also serves as an electrode terminal that exchanges electric power with the outside.

(Other forms of this form)
In this embodiment, an example in which the carbon composite of the present invention is used for the positive electrode of a lithium air secondary battery has been described. However, the use of the carbon composite of the present invention is not limited to only a lithium air secondary battery. . For example, you may use for the air battery using magnesium, aluminum, calcium, and another conventionally well-known air secondary battery.

Hereinafter, the present invention will be described more specifically with reference to examples.
As examples, lithium ion secondary batteries and lithium air secondary batteries were prepared.

[Lithium ion secondary battery]
Example 1
First, the carbon composite of the component composition shown in Table 1 was prepared. The component composition, pore volume, and supporting state of zinc and a metal-based material (Si in this embodiment) were confirmed by the following method.

The component composition of the carbon composite was confirmed by ICP emission analysis. Specifically, after ashing the carbon composite, the components were sequentially dissolved with an alkali and an acid to obtain a solution. By performing ICP emission analysis on this solution, it was confirmed that the component composition of the carbon composite was as described in Table 1.
The pore volume was confirmed by the X-ray small angle scattering method. Specifically, the radial distribution function of pores (nanopores) was derived by the X-ray small angle scattering method and shown in FIG. As shown in FIG. 1, two peaks centered around pore diameters of 5 nm and 25 nm can be confirmed, and the pore diameter is less than 10 nm (Comp. 1 in the figure) and 10 nm or more (Comp. 2 and Comp in the figure). .) 3) can be distinguished. A peak (Comp. 3) having a center in the vicinity of 45 nm is further separated from the pores of 10 nm or more. The volume fraction of nanopores was calculated from the three separated peaks.
Confirmation of the loading state of the carbon composite was confirmed by taking a TEM photograph. A photographed TEM photograph is shown in FIG. FIG. 2 shows that zinc and metal-based material (Si) are supported in the nanopores.

  A carbon composite: 85 parts by mass, Ketjen black (conductive material): 5 parts by mass, PVDF (binder): 10 parts by mass were prepared and dispersed in NMP to prepare a slurry. The prepared slurry was applied on an electrolytic copper foil having a thickness of 18 μm so as to be 5.0 mg / φ14 mm, and then dried and press-molded. Then, it extracted with the circular punch of (phi) 14 mm, and was vacuum-dried at 120 degreeC for 6 hours, and was set as the negative electrode.

Next, LiPF ₆ is adjusted to 1 mol / L in a mixed solvent of the negative electrode thus produced, metallic lithium as the positive electrode (counter electrode), and 30 vol% ethylene carbonate (EC) and 70 vol% diethyl carbonate (DEC). A coin-type non-aqueous electrolyte type lithium ion secondary battery (CR2025 type) was manufactured by assembling in a dry box using an electrolyte solution prepared by dissolving in an electrolyte.

In addition, the lithium ion secondary battery of a present Example was assembled by laminating | stacking a positive electrode and a negative electrode through the separator made from a polypropylene, and sealing and sealing a case with electrolyte solution.
Thus, the lithium ion secondary batteries of Samples 1 and 2 of this example were manufactured.

(Comparative Example 1)
First, a carbon composite having the composition shown in Table 1 was prepared. The carbon composite of this comparative example does not contain a metal-based material (Si). The composition of the carbon composite was confirmed in the same manner as in Example 1.

Thereafter, in the same manner as in Example 1, a coin-type non-aqueous electrolyte type lithium ion secondary battery (CR2025 type) was produced.
Thus, lithium ion secondary batteries of Samples 3 to 5 of this comparative example were manufactured.

(Evaluation)
As evaluation of the lithium ion secondary battery of Example 1 and Comparative Example 1, the capacity retention rate and the charge / discharge efficiency were measured. The measurement results are shown in Table 1.
Specifically, first, conditioning is performed on the assembled lithium ion secondary battery.

Subsequently, at an atmospheric temperature of 60 ° C., charge and discharge were repeated with CC-CV charge (1C, 4.0 V) and CC discharge (up to 2.0 V) as one cycle. The ratio of the 50th discharge capacity to the fifth discharge capacity was calculated and used as the capacity retention rate.
In addition, the charge capacity was also measured at the fifth time, and the ratio of (charge capacity) / (discharge capacity) was calculated from the measured charge capacity and discharge capacity to obtain charge / discharge efficiency.

  As shown in Table 1, it can be confirmed that the lithium ion secondary battery of Example 1 is superior in capacity retention rate and charge / discharge efficiency to the lithium ion secondary battery of Comparative Example 1. From this, it can be seen that by using a carbon composite having a predetermined amount of zinc and a metal-based material at the same time as the negative electrode active material, it was possible to suppress a decrease in cycle characteristics.

[Lithium air secondary battery]
(Example 2)
First, a carbon composite having the composition shown in Table 2 was prepared. The composition of the carbon composite was confirmed in the same manner as in Example 1.

First, carbon combined with 0 to 1 mass% zinc, potassium permanganate (KMnO ₄ ), and sulfuric acid were dissolved in ultrapure water and refluxed at 70 ° C. for 4 hours while applying ultrasonic vibration of 20 kHz. It was. After refluxing, the solid was filtered off and subjected to heat treatment (baking) at 250 ° C. for 3 hours to produce a carbon composite carrying manganese oxide (MnO _x ). When this carbon composite was subjected to thermogravimetric analysis, the amount of MnO _x in the carbon composite was 21 mass%.

Carbon composite supporting manganese oxide (MnO _x ) was mixed with 10 mass% of PTFE (binder) with respect to 90 mass% (mixed at a mass ratio of 9: 1), and the mixture was dispersed in ethanol and kneaded, Molded into a sheet. The obtained sheet was rolled and punched into a predetermined shape. The punched sheet was placed on the surface of a current collector made of nickel mesh, and pressed and pressed under conditions of 5 MPa, 180 ° C. for 3 minutes. After pressure bonding, vacuum drying was performed at 120 ° C. for 8 hours. Thus, the positive electrode for an air battery of this example was manufactured.

Next, metallic lithium was punched into the same shape as the above-described positive electrode for an air battery, and the negative electrode for an air battery of this example was manufactured.
LiPF ₆ was dissolved in a mixed solvent obtained by mixing ethylene carbonate (EC) at 30 vol% and 1,2-dimethoxyethane (DME) at 70 vol% so as to be 1 mol / L. A non-aqueous electrolyte was produced.

Using the above positive electrode, negative electrode, non-aqueous electrolyte, and the like, a lithium air secondary battery C whose main components are shown in FIG. 3 was assembled in the following procedure. In addition, the lithium air secondary battery C of a present Example is the same as that of the conventional lithium air secondary battery except the structure mentioned.
First, in a glove box under an argon atmosphere, both surfaces of the negative electrode 2 were ground with edges of a glass plate to remove oxides formed on the surface. This search exposed a surface of lithium metal with a metallic luster. And the negative electrode 2 was installed in the lower casing 4 made of stainless steel.

And the positive electrode 1 was set in the state through the separator 7 formed by stacking two porous films (manufactured by TOYO, GA-55) having a thickness of 0.025 mm. The positive electrode 1 was set so that the surface on which the porous carbon provided with the graphene layer carrying MnO _x was opposed to the negative electrode 2. Then, the nonaqueous electrolyte 3 was injected between the current collector 12 of the positive electrode 1 and the negative electrode 2.

  Thereafter, a carbon paper 13 having a thickness of 0.025 mm impregnated with PTFE (EC-TP1-H090T, manufactured by Toray Co., Ltd.) is placed on the current collector 12, and the first SUS product is made through an O-ring 6 for sealing. The upper casing 51 was attached, and the second upper casing 52 was further attached. The lower casing 4 was assembled, and the cells were fixed by caulking jigs (not shown). The carbon paper 13 is used as a gas diffusion layer in this example.

  Further, pure oxygen gas is supplied so that the pressure in the gas chamber 14 after filling from the filling tank (not shown) into the gas chamber 14 provided in the hollow portion inside the first upper casing 51 becomes 0.01 MPa. Filled. Thereafter, the gas chamber 14 was sealed. The positive electrode 1 is formed by a current collector 12 provided with a catalyst sheet 11, a carbon paper 13 covering the upper surface of the current collector 12, and oxygen gas in a gas chamber 14 that is in contact with the current collector 12 via the carbon paper 13. The air electrode.

Although not shown, the second upper casing 52 is provided with a terminal that is electrically connected to the positive electrode 1 through a nickel wire crimped to the current collector 12 and is insulated from the second upper casing 52. It has been. Similarly, the lower casing 4 is provided with a terminal that is electrically connected to the negative electrode 2 and insulated from the lower casing 4.
Thus, the lithium air secondary battery C of Sample 6 of this example was manufactured.

(Comparative Example 2)
Comparative Example 2 is a lithium-air battery similar to Example 2 except that the positive electrode material is different.
Specifically, in place of the carbon composite supporting the manganese oxide (MnO _x ) of Example 2, Ketjen black (made by Lion, trade name: ECP600JD) and electrolytic MnO ₂ (made by Tosoh Corporation) serving as a catalyst , Trade name: FMH).

(Evaluation)
As evaluation of the lithium air secondary battery of Example 2 and Comparative Example 2, the charge capacity and the discharge capacity were measured. The measurement results are shown in Table 2.
Specifically, each air secondary battery is connected to a charge / discharge device (HJ1001SM8A type) manufactured by Hokuto Denko Corporation, constant current discharge between positive electrode 1 and negative electrode 2, rest for 10 minutes, constant current charge, 10 The battery capacity (discharge capacity and charge capacity) during constant current charging / discharging was measured after a pause of minutes.

The lithium-air secondary battery was discharged at a constant current of 0.125 mA (0.25 mA / cm ² per unit weight of the positive electrode material) until it reached 2V. In the constant current charging, a current of 0.125 mA (0.25 mA / cm ² per unit weight of the positive electrode material) was passed, and charging was performed until the voltage reached 4.2V.
The ratio of the fifth discharge capacity to the first discharge capacity was calculated and used as the capacity retention rate.

  As shown in Table 2, it can be confirmed that the lithium-air secondary battery of Example 2 is superior in capacity retention rate to the lithium-air secondary battery of Comparative Example 2. From this, it can be seen that by using a carbon composite having a predetermined amount of zinc and a metal-based material at the same time for the positive electrode, a decrease in cycle characteristics could be suppressed.

C: Lithium air secondary battery 1: Positive electrode 11: Catalyst sheet 12: Current collector 13: Carbon paper 14: Gas chamber 2: Negative electrode 3: Non-aqueous electrolyte 4: Lower casing 51: First upper casing 52: First Upper casing of 2 6: O-ring for sealing 7: Separator

Claims (10)

When the whole is 100 mass%, zinc that is greater than 0 mass% and less than 1 mass% and is capable of electrochemically reacting with at least one of alkali metals and alkaline earth metals, transition metals, alloys thereof, A carbon composite composed of a metal-based material selected from these composite oxides and the remaining carbon,
A carbon composite characterized in that when the pore distribution is measured, the volume occupied by pores having a pore diameter of 10 to 60 nm is 40 vol% or more.   The carbon composite according to claim 1, wherein the carbon forms a porous carbon base material, and the zinc and the metal-based material are supported on a surface of the porous carbon base material.   The carbon composite according to claim 2, wherein the zinc and the metal material are supported in pores of the porous carbon substrate.   The carbon composite according to any one of claims 1 to 3, wherein the metallic material contains at least one of Sn and Si at 20 mass% or more and 60 mass% or less.   The carbon composite according to any one of claims 1 to 4, which is used for a lithium ion secondary battery.   Examples of the metal-based material include V, Cr, Mn, Fe, Co, Ni, Mo, Ru, Pd, Ag, Pt, and Au, alloys containing the metal, composite oxides containing the metal, and metal phthalocyanines. The carbon composite according to claim 1, which is at least one kind.   The carbon composite according to claim 1, which is used for a lithium-air secondary battery.   An electrical storage device using the carbon composite according to any one of claims 1 to 7 as an electrode, and lithium ions serving as an electric capacity.   The electricity storage device according to claim 8, which is a lithium ion secondary battery using the carbon composite according to any one of claims 1 to 5 as a negative electrode.   The electrical storage device according to claim 8, which is a lithium-air secondary battery (C) using the carbon composite according to any one of claims 1 to 3 and 6 to 7 as a positive electrode (1).