JP2019057489A - Positive electrode for air cell and air cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positive electrode for an air battery capable of realizing an air battery capable of obtaining both a high discharge capacity and a high volume energy density. An air battery positive electrode of the present disclosure is an air battery positive electrode including a carbon-containing porous body, wherein the porous body has first pores having a pore size of 4 nm or more and less than 100 nm. In the porous body, the second pore volume, which is the cumulative pore volume of the second pores, includes the second pores having a pore diameter of 100 nm or more and 10 μm or less. It is larger than the first pore volume, which is the pore volume. [Selection diagram] Figure 1

Description

  The present disclosure relates to a positive electrode for air battery and an air battery.

  An air battery is a battery using oxygen in air as a positive electrode active material and a metal or compound capable of inserting and extracting metal ions as a negative electrode active material. The air battery has advantages such as high energy density (amount of power that can be discharged with respect to weight), and easy size and weight reduction. Therefore, the air battery is attracting attention as a battery having an energy density exceeding the metal ion battery which is currently considered to have the highest energy density.

  The air battery includes a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode. In general, a conductive material is used for the positive electrode. As the conductive material, for example, carbon materials such as graphite and acetylene black are used.

JP, 2010-12198, A

  The present disclosure provides a positive electrode for an air battery that can realize an air battery capable of obtaining both a high discharge capacity and a high volumetric energy density.

  The positive electrode for an air battery according to an aspect of the present disclosure is a positive electrode for an air battery comprising a porous body containing carbon, wherein the porous body has a first pore having a pore diameter of 4 nm or more and less than 100 nm; And a second pore having a pore diameter of 100 nm to 10 μm, and in the porous body, a second pore volume which is a cumulative pore volume of the second pore is a cumulative pore size of the first pore. The pore volume is larger than the first pore volume.

  The positive electrode for an air battery of the present disclosure can realize an air battery capable of obtaining both a high discharge capacity and a high volumetric energy density.

FIG. 1 is a schematic cross-sectional view showing one configuration example of the air battery of the present disclosure.

<Findings underlying the present disclosure>
Patent Document 1 discloses an air battery provided with a positive electrode containing carbon. In this air battery, the crystallite diameter of carbon used for the positive electrode is 15 Å or less calculated from the Scherrer's equation in X-ray diffraction measurement. Furthermore, in Patent Document 1, the specific surface area of carbon used for the positive electrode is 750 m ² / g or more, and the total pore volume obtained by the mercury intrusion method is 4.0 ml / g or more and 5.5 ml / g or less It is also disclosed that some.

  The air battery provided with the positive electrode consisting of carbon and a binder described in Patent Document 1 can obtain a large discharge capacity. However, in the positive electrode described in Patent Document 1, it was found by the study of the present inventors that expansion occurs with discharge and the volumetric energy density decreases. That is, the air battery using the conventional positive electrode has a problem of low volume energy density. Then, the present inventors considered to the positive electrode and air battery for air batteries of this indication shown below, as a result of earnestly examining in order to solve the said problem.

<Summary of an aspect of the present disclosure>
The positive electrode for an air battery according to the first aspect of the present disclosure is a positive electrode for an air battery comprising a porous body containing carbon, wherein the porous body has a first pore having a pore diameter of 4 nm or more and less than 100 nm. And a second pore having a pore diameter of 100 nm or more and 10 μm or less, and in the porous body, a second pore volume which is a cumulative pore volume of the second pore is the same as that of the first pore. Greater than the first pore volume, which is the cumulative pore volume.

  The positive electrode for an air battery according to the first aspect includes a porous body in which the first pore volume and the second pore volume satisfy the above relationship. According to this configuration, the positive electrode for an air battery according to the first aspect can improve the discharge capacity of the air battery, and can suppress expansion of the positive electrode accompanying discharge and can also improve the volume energy density. Therefore, the positive electrode for an air battery according to the first aspect can realize an air battery capable of obtaining both a high discharge capacity and a high volumetric energy density.

In a second aspect, for example, in the air battery positive electrode according to the first aspect, the sum of the first pore volume and the second pore volume, 2.6 cm ³ / g or more 4.0 cm ³ / It may be less than or equal to g.

  In the positive electrode for an air battery according to the second aspect, the sum of the first pore volume and the second pore volume satisfies the above range, in other words, it can be said that the positive electrode contains many pores. Therefore, the positive electrode for an air battery according to the second aspect sufficiently includes a reaction space for a discharge reaction for producing a discharge product and a storage space for storing the produced discharge product. Thereby, the positive electrode for an air battery according to the second aspect can increase the discharge capacity.

In the third aspect, for example, in the positive electrode for an air battery according to the first or second aspect, the second pore volume may be 1.4 cm ³ / g or more and 3.0 cm ³ / g or less.

  In the positive electrode for an air battery according to the third aspect, it can be said that the second pore volume satisfies the above range, in other words, the positive electrode contains a large number of second pores having a large pore diameter. Therefore, the positive electrode for an air battery according to the third aspect sufficiently includes a storage space for storing a discharge product generated by the discharge reaction. Thereby, the air battery positive electrode according to the third aspect can further suppress the expansion of the positive electrode.

  In the fourth aspect, for example, in the positive electrode for air battery according to any one of the first to third aspects, the surface functional group content of the carbon contained in the porous body is 0.3 mmol / g or more. .4 mmol / g or less.

  In the positive electrode for an air battery according to the fourth aspect, the first pore volume and the second pore volume satisfy the above relationship, and the amount of surface functional groups of carbon contained satisfies the above specific range. Containing porous body. With this configuration, the positive electrode for an air battery according to the fourth aspect can suppress the expansion of the positive electrode associated with the discharge, and can also suppress the clogging of the porous body by the discharge product generated by the discharge reaction. Therefore, the positive electrode for an air battery according to the fourth aspect can realize an air battery capable of obtaining both a high discharge capacity and a high volumetric energy density.

  In the fifth aspect, for example, in the positive electrode for an air battery according to the fourth aspect, the amount of surface functional groups of the carbon contained in the porous body is 0.38 mmol / g or more and 1.34 mmol / g or less .

  The air battery positive electrode according to the fifth aspect can realize an air battery capable of obtaining both a high discharge capacity and a high volumetric energy density.

  In the sixth aspect, for example, the positive electrode for an air battery according to any one of the first to fifth aspects includes a positive electrode layer that can be oxidized and reduced using oxygen in air as a positive electrode active material, The porous body is included in the positive electrode layer, and the volume resistivity of the positive electrode layer in the direction parallel to the main surface measured on the main surface of the positive electrode layer is 5500 mOhm · cm or less.

  In the positive electrode for an air battery according to the sixth aspect, even if the non-conductive discharge product is deposited by the discharge reaction, it is possible to maintain a large area capable of reaction. Therefore, the positive electrode for an air battery according to the sixth aspect can increase the deposition amount of the discharge product to further improve the volumetric energy density. That is, the positive electrode for an air battery according to the sixth aspect can further improve the discharge capacity and the volumetric energy density.

  In the seventh aspect, for example, in the positive electrode for an air battery according to the sixth aspect, the volume resistivity may be 2500 mOhm · cm or less.

  The positive electrode for an air battery according to the seventh aspect can maintain a large area capable of reaction even if a non-conductive discharge product is deposited by the discharge reaction. Therefore, the positive electrode for an air battery according to the seventh aspect can increase the deposition amount of the discharge product to further improve the volumetric energy density. That is, the positive electrode for an air battery according to the seventh aspect can further improve the discharge capacity and the volumetric energy density.

  In the eighth aspect, for example, in the air cell positive electrode according to any one of the first to seventh aspects, when the first pore volume is V1 and the second pore volume is V2, 1 4 ≦ V2 / V1 is satisfied.

  The air cell positive electrode according to the eighth aspect can store more discharge products in the positive electrode. Therefore, the air battery positive electrode according to the eighth aspect can further suppress the expansion of the positive electrode.

  In a ninth aspect, for example, in the positive electrode for an air battery according to the eighth aspect, the V1 and the V2 satisfy 1.5 ≦ V2 / V1.

  The air battery positive electrode according to the ninth aspect can store more discharge products in the positive electrode. Therefore, the air battery positive electrode according to the ninth aspect can further suppress the expansion of the positive electrode.

  In a tenth aspect, for example, in the positive electrode for an air battery according to the ninth aspect, the V1 and the V2 satisfy 2.5 ≦ V2 / V1.

  The air battery positive electrode according to the tenth aspect can store more discharge products in the positive electrode. Therefore, the air battery positive electrode according to the tenth aspect can further suppress the expansion of the positive electrode.

  In an eleventh aspect, for example, in the positive electrode for an air battery according to the tenth aspect, the V1 and the V2 satisfy 3 ≦ V2 / V1.

  The air battery positive electrode according to the eleventh aspect can store more discharge products in the positive electrode. Therefore, the air battery positive electrode according to the eleventh aspect can further suppress the expansion of the positive electrode.

  An air battery according to a twelfth aspect of the present disclosure includes the positive electrode for an air battery according to any one of the first to eleventh aspects, a negative electrode capable of inserting and extracting metal ions, the positive electrode, and the negative electrode And an electrolyte layer disposed between the two.

  The air battery according to the twelfth aspect is provided with the air cell positive electrode according to any one of the first to eleventh aspects, so that both high discharge capacity and high volume energy density can be obtained. .

Embodiment
Hereinafter, embodiments of the positive electrode for air battery of the present disclosure and the air battery will be described in detail. The following embodiment is an example, and the present disclosure is not limited to the following embodiment.

  The air battery of the present embodiment comprises a positive electrode for air battery (hereinafter referred to as "positive electrode"), a negative electrode capable of inserting and extracting metal ions, and an electrolyte layer disposed between the positive electrode and the negative electrode. Is equipped. The positive electrode includes a positive electrode layer that can be oxidized and reduced using oxygen in air as a positive electrode active material. The positive electrode may further include a positive electrode current collector for collecting current in the positive electrode layer. In addition, the negative electrode includes a negative electrode layer capable of inserting and extracting metal ions. The negative electrode may further include a negative electrode current collector for collecting current in the negative electrode layer. The air battery of the present embodiment may further include a separator disposed between the positive electrode and the negative electrode. A schematic cross-sectional view of one configuration example of such an air battery is shown in FIG.

  The air battery 1 illustrated in FIG. 1 includes a battery case 11, a negative electrode 12, a positive electrode 13, and an electrolyte layer 14. The battery case 11 has a cylindrical portion 11a opened on both the top and bottom sides, a bottom portion 11b provided to close the opening on the bottom of the cylindrical portion 11a, and an opening on the upper surface of the cylindrical portion 11a. And a lid 11c provided to close the cover. Although not shown, the battery case 11 has a configuration capable of taking in air inside. For example, the lid portion 11 c may be provided with an air intake hole for taking air into the battery case 11. The negative electrode 12 is composed of a negative electrode layer 12 a and a negative electrode current collector 12 b. The negative electrode layer 12 a is disposed on the electrolyte layer 14 side with respect to the negative electrode current collector 12 b. The positive electrode 13 is composed of a positive electrode layer 13a and a positive electrode current collector 13b. The positive electrode layer 13a is disposed on the electrolyte layer 14 side with respect to the positive electrode current collector 13b. The positive electrode current collector 13 b is provided with an air intake hole 15 for taking air into the positive electrode layer 13 a. A frame 16 is provided on the side surface of the laminate composed of the negative electrode 12, the electrolyte layer 14 and the positive electrode 13. Although not shown, the air battery 1 may further include a separator included in the electrolyte layer 14.

  Hereinafter, a lithium-air battery is described as an example of the air battery of the present embodiment. However, the air battery of the present embodiment is not limited to the lithium air battery, and may be an air battery using a metal other than lithium.

When the air battery of the present embodiment is a lithium air battery, the battery reaction is as follows.
Discharge reaction (when using battery)
^{Negative: 2Li → 2Li + + 2e -} (1)
Positive electrode: 2Li ⁺ + 2e ⁻ + O ₂ → Li ₂ O ₂ (2)
Charge reaction (at the time of battery charge)
^{Negative: 2Li + + 2e - → 2Li} (3)
Positive electrode: Li ₂ O ₂ → 2Li ⁺ + 2e ⁻ + O ₂ (4)

  At the time of discharge, as shown in the formulas (1) and (2), electrons and lithium ions are released from the negative electrode, while oxygen and lithium ions taken from the outside of the battery react with each other while taking in the electrons at the positive electrode. Produces an oxide. In the case of a lithium-air battery, this lithium oxide is a discharge product. Further, at the time of charging, as shown in the formulas (3) and (4), lithium ions are taken in together with electrons at the negative electrode, and lithium ions and oxygen are released together with the electrons at the positive electrode.

  Next, each configuration of such an air battery will be described in detail.

1. Positive Electrode As described above, the positive electrode includes the positive electrode layer, and may further include the positive electrode current collector. The positive electrode layer and the positive electrode current collector will be respectively described below.

(1) Positive Electrode Layer The positive electrode layer contains a material capable of oxidizing and reducing oxygen in the air as a positive electrode active material. As such a material, the positive electrode layer in the present embodiment contains a conductive porous body containing carbon. The carbon material used as such a porous body may have high electron conductivity. Specifically, carbon materials such as acetylene black and ketjen black which are generally used as a conductive aid may be used. Among these carbon materials, conductive carbon black such as ketjen black may be used in view of specific surface area and primary particle size. The specific surface area of the carbon material, for example, be a 800~2000m ² / g, it may be 1200~1600m ² / g. By setting the specific surface area of the carbon material within such a range, it becomes easy to form a positive electrode layer having a characteristic pore structure described later. Here, the specific surface area is a value measured by the BET method.

  In addition, the amount of surface functional groups of carbon contained in the porous body may satisfy the specific range described later. Therefore, the carbon material used for producing the porous body may be appropriately selected so that the amount of surface functional groups of carbon contained in the porous body falls within the specific range, and the plurality of surface functional groups differ from each other It may be a mixture of carbon materials. For example, a porous body in which the amount of surface functional groups of carbon satisfies a specific range may be realized by appropriately adjusting the mixing ratio of two or more types of carbon materials having different amounts of surface functional groups.

  The porous body contained in the positive electrode layer may contain pores having a pore size of 4 nm to 10 μm. Here, in the porous body, a pore having a pore diameter of 4 nm or more and less than 100 nm is defined as a first pore, and a pore having a pore diameter of 100 nm or more and 10 μm or less is defined as a second pore. Furthermore, in the porous body, the cumulative pore volume of the first pore is defined as a first pore volume, and the cumulative pore volume of the second pore is defined as a second pore volume. In the present embodiment, in the porous body, the second pore volume is larger than the first pore volume. That is, in the air battery of the present embodiment, the pore volume of the porous body contained in the positive electrode layer is the second pore having a larger pore diameter than the ratio occupied by the first pores having the small pore diameter. The proportion occupied by is greater. In other words, it can be said that the positive electrode layer contains a porous body in which a large number of pores having a large pore diameter are present.

  As described above, in the lithium-air battery, lithium oxide is formed at the positive electrode during discharge. The lithium oxide is generated and accumulated in the void portion of the positive electrode layer, ie, the pores of the porous body. In the conventional air battery, the porous body constituting the positive electrode contains many pores having a relatively small pore diameter. In the conventional positive electrode having such a configuration, the lithium oxide is precipitated in the small pores of the porous body, and then the lithium oxide is largely grown in the small pores as the capacity is increased. Of the pores expand and the positive electrode expands. On the other hand, in the positive electrode in the present embodiment, as described above, the porous body includes the first pore which is a small pore and the second pore which is a large pore, and the second pore volume is Greater than the first pore volume. With this configuration, in the positive electrode of the present embodiment, lithium oxide precipitates in small pores (first pores) at the time of discharge, and lithium oxide also precipitates in large pores (second pores) simultaneously. . The second pore volume is larger than the first pore volume and has a volume sufficient to store the deposited lithium oxide. Therefore, in the second pore, the lithium oxide grown large can be stored. Therefore, the positive electrode in the present embodiment can suppress the expansion of the positive electrode due to the growth of the discharge product. As a result, the air battery of the present embodiment can improve the volumetric energy density as compared with the conventional air battery.

In order to increase the discharge capacity and the volumetric energy density, the sum of the first pore volume and the second pore volume may be large. The sum of the first and second pore volumes is the cumulative pore volume of the first and second pores. In the present embodiment, the sum of the first pore volume and the second pore volume may also be 2.6 cm ³ / g or more, may be 3.3 cm ³ / g or more. By the sum of the first pore volume and the second pore volume being larger, the positive electrode can enlarge both the reaction interface where lithium oxide is formed and the storage space of lithium oxide. Therefore, the air battery provided with such a positive electrode can further improve the discharge capacity and the volumetric energy density. In addition, the sum of the first pore volume and the second pore volume may be 4.0 cm ³ / g or less.

The range of the second pore volume is not particularly limited. However, the second pore volume may be large in consideration of securing of a still higher discharge capacity and improvement of volumetric energy density. The second pore volume, for example may also be 1.4 cm ³ / g or more, it may be 2.1 cm ³ / g or more. By increasing the second pore volume, the storage space for storing lithium oxide can be increased, and thus the expansion of the positive electrode can be further suppressed. In addition, the second pore volume may be 3.0 cm ³ / g or less.

  When the first pore volume is V1 and the second pore volume is V2, 1.1 ≦ V2 / V1 may be satisfied, and 1.2 ≦ V2 / V1 may be satisfied, and 1.4 ≦ V2 / V1 may be satisfied, and 1.5 ≦ V2 / V1 may be satisfied. Furthermore, 1.6 ≦ V2 / V1 may be satisfied, 1.8 ≦ V2 / V1 may be satisfied, 2.5 ≦ V2 / V1 may be satisfied, 2.6 ≦ V2 / V1 may be satisfied, or 3 ≦ V2 / V1 may be satisfied. The fact that V2 / V1 is large means, in other words, that the positive electrode contains many pores having a large pore size of μm size. Therefore, such a positive electrode is sufficiently provided with a storage space for storing lithium oxide, and expansion of the positive electrode can be suppressed to improve volume energy density. Note that V1 and V2 may satisfy V2 / V1 ≦ 5.

  Furthermore, the amount of surface functional groups of carbon contained in the porous body is, for example, 0.3 mmol / g or more and 1.4 mmol / g or less. In the present disclosure, the surface functional group of carbon is an acidic functional group, and examples thereof include a carboxyl group, a phenolic hydroxyl group and a lactone group. The document "Wong et al, Chemistry of Materials, 2016, 28 (21), pp 8006-8015" discloses that the surface functional group changes the adsorption rate of oxygen and lithium ions on the carbon surface . When the adsorption rates of oxygen and lithium ions on the carbon surface are different, the deposition rate of lithium oxide by the discharge reaction occurring on the surface of the porous body is different. That is, in the porous body of the positive electrode layer, there are both a place where the deposition rate of lithium oxide is high and a place where the deposition rate is low. In other words, there are both places where lithium oxide is likely to precipitate and places where it is difficult to precipitate. By the carbon contained in the porous body in the present embodiment having a surface functional group in an amount within the above-mentioned specific range, a place where lithium oxide is likely to be precipitated and the precipitation in the porous body. Places that are difficult to be placed can be arranged in a well-balanced manner. When it has such a structure, the porous body of the positive electrode layer of this embodiment can prevent blocking of the positive electrode layer by lithium oxide. That is, when it has such a structure, the positive electrode layer of the present embodiment can cause a sufficient discharge reaction at a place where the discharge product tends to precipitate, and at the same time, the place where the discharge product does not easily precipitate is air and It can be secured as a space for metal ions to diffuse. As a result, the air battery of the present embodiment can further improve the volumetric energy density as compared with the conventional air battery.

  The amount of surface functional groups of carbon contained in the porous body may be 0.38 mmol / g or more. In addition, the amount of surface functional groups of carbon contained in the porous body may be 1.34 mmol / g or less.

  In order to increase the discharge capacity and the volumetric energy density, the volume resistivity of the positive electrode layer in the direction parallel to the main surface measured on the main surface of the positive electrode layer may be low. In addition, the volume resistivity of the positive electrode layer specified here is a value measured on the main surface of a positive electrode layer as mentioned above, Comprising: It measures using the four-probe method. In the four-point probe method, since it is not necessary to form an electrode on a measurement target, it is possible to measure the volume resistivity on the main surface of the positive electrode layer without preparing a separate measurement sample. The volume resistivity may be, for example, 5500 mOhm cm or less, 5126 mOhm cm or less, 2500 mOhm cm or less, or 2162 mOhm cm or less. The lower electric resistance of the positive electrode layer can increase the reaction interface at which lithium oxide is generated. Therefore, the positive electrode provided with the positive electrode layer having a low volume resistivity can maintain a large area capable of reaction even if a non-conductive discharge product is deposited by the discharge reaction. Therefore, further improvement of the discharge capacity and the volumetric energy density can be realized by the positive electrode layer having the lower volume resistivity.

  The lower limit value of the volume resistivity is not particularly limited, but may be, for example, 18 mOhm · cm or more. The lower limit value of the volume resistivity does not become lower than the powder resistance value of the carbon material, so here, the powder resistance value of the carbon material is taken as the lower limit value.

  The positive electrode layer may be provided with the above-mentioned porous body, but may further contain a binder for immobilizing the above-mentioned porous body. A well-known material can be used as a binder of the positive electrode layer of an air battery as a binder, For example, polyvinylidene fluoride (PVdF), a polytetrafluoroethylene (PTFE), etc. can be mentioned. The content of the binder in the positive electrode layer is not particularly limited, but may be, for example, in the range of 1% by mass to 40% by mass.

  The thickness of the positive electrode layer is not particularly limited because it varies depending on the use of the air battery and the like, but may be, for example, in the range of 2 μm to 500 μm, and may be in the range of 5 μm to 300 μm.

  The positive electrode layer is formed, for example, by forming a paint in which a raw material of a porous body constituting the positive electrode layer, a binder, and a sublimable powder are dispersed in a solvent, and removing the sublimable powder and the solvent by heat treatment. The porous film can be produced by using a method such as pressing and the like on the positive electrode current collector described below. The sublimable powder functions as a pore forming agent. Therefore, the porous film produced by using the sublimable powder as described above can realize the desired pore structure, that is, the pore structure having the features described in the present embodiment.

(2) Positive Electrode Current Collector The positive electrode current collector carries out current collection of the positive electrode layer. Therefore, the material of the positive electrode current collector is not particularly limited as long as it has conductivity, and a known material can be used as the positive electrode current collector of the air battery. Examples of the material of the positive electrode current collector include stainless steel, nickel, aluminum, iron, titanium, carbon and the like. As a shape of a positive electrode collector, foil shape, plate shape, mesh (grid) shape etc. can be mentioned, for example. Among these, in the present embodiment, the shape of the positive electrode current collector may be mesh-like. This is because the mesh-like positive electrode current collector is excellent in current collection efficiency. In this case, a mesh-like positive electrode current collector may be disposed inside the positive electrode layer. Furthermore, the air battery of the present embodiment may further include another positive electrode current collector (for example, a foil-like current collector) that collects the charge collected by the mesh-like positive electrode current collector. . In the present embodiment, a battery case described later may have the function of a positive electrode current collector.

  The thickness of the positive electrode current collector can be, for example, in the range of 10 μm to 1000 μm, and may be in the range of 20 μm to 400 μm.

2. Negative Electrode As described above, the negative electrode includes the negative electrode layer, and may further include the negative electrode current collector. The negative electrode layer and the negative electrode current collector will be respectively described below.

(1) Negative Electrode Layer The negative electrode layer in the present embodiment contains at least a negative electrode active material capable of inserting and extracting lithium ions. Such a negative electrode active material is not particularly limited as long as it is a substance containing a lithium element, but for example, a simple metal (lithium metal), an alloy containing a lithium element, an oxide containing a lithium element, and the like The nitride etc. which contain a lithium element can be mentioned. As an alloy which has a lithium element, a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, a lithium silicon alloy etc. can be mentioned, for example. Moreover, as a metal oxide containing a lithium element, a lithium titanium oxide etc. can be mentioned, for example. Moreover, as a metal nitride containing a lithium element, lithium cobalt nitride, lithium iron nitride, lithium manganese nitride etc. can be mentioned, for example.

  The negative electrode layer may contain only the negative electrode active material, or may contain a binder in addition to the negative electrode active material. For example, when the negative electrode active material is in the form of a foil, the negative electrode layer can contain only the negative electrode active material. On the other hand, when the negative electrode active material is powdery, it can be a negative electrode layer containing the negative electrode active material and a binder. As a binder, a well-known material can be used as a binder of the negative electrode layer of an air battery, For example, PVdF, PTFE, etc. can be mentioned. The content of the binder in the negative electrode layer is not particularly limited, but may be, for example, in the range of 1% by mass to 40% by mass. Moreover, as a method of forming a negative electrode layer using a powdery negative electrode active material, it is possible to use a doctor blade method, a molding method using a pressure press, or the like, as in the above method of forming a positive electrode layer.

(2) Negative electrode current collector The negative electrode current collector carries out current collection of the negative electrode layer. The material of the negative electrode current collector is not particularly limited as long as it has conductivity, and a known material can be used as a negative electrode current collector of a lithium air battery. As an example of the material of a negative electrode collector, copper, stainless steel, nickel, carbon etc. can be mentioned, for example. As a shape of a negative electrode collector, foil shape, plate shape, mesh (grid) shape etc. can be mentioned, for example. In the present embodiment, a battery case described later may have the function of the negative electrode current collector.

3. Separator The lithium-air battery of the present embodiment may include a separator disposed between the positive electrode (positive electrode layer) and the negative electrode (negative electrode layer). By arranging a separator between the positive electrode and the negative electrode, a battery with high safety can be obtained. The separator is not particularly limited as long as it has a function of electrically separating the positive electrode layer and the negative electrode layer, and for example, porous films such as polyethylene (PE) and polypropylene (PP), PE and PP And resin non-woven fabrics, glass fiber non-woven fabrics, and porous insulating materials such as paper non-woven fabrics.

  The separator may have a porosity in the range of 30 to 90%. When the porosity is less than 30%, it may be difficult for the separator to sufficiently hold the electrolyte when the separator holds the electrolyte. On the other hand, when the porosity exceeds 90%, sufficient separator strength may not be obtained. The porosity of the separator may be 35 to 60%.

4. Electrolyte Layer The electrolyte layer is a layer disposed between the positive electrode (positive electrode layer) and the negative electrode (negative electrode layer) to conduct lithium ions. Therefore, the form of the electrolyte layer is not particularly limited as long as it has lithium ion conductivity (lithium ion conductor), and a solution system represented by an organic solvent system containing a salt of lithium as an electrolyte, and And any form of solid membrane system represented by the system of polymer solid electrolyte containing a salt of lithium.

  When the electrolyte layer is a solution system, a non-aqueous electrolytic solution prepared by dissolving a lithium salt in a non-aqueous solvent can be used as the electrolyte layer.

Examples of the lithium salt contained as an electrolyte in the non-aqueous electrolytic solution include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), trifluoromethanesulfonic acid Lithium (LiCF ₃ SO ₃ ) and bistrifluoromethanesulfonylamide lithium (LiN (CF ₃ SO ₂ ) ₂ ), etc. may be mentioned, but not limited thereto, they are known as electrolytes of non-aqueous electrolytes of air batteries Lithium salts can be used.

  The amount of electrolyte dissolved in the non-aqueous solvent is, for example, 0.5 to 2.5 mol / l. When a solution-based electrolyte layer (non-aqueous electrolyte solution) is used, as described above, the non-aqueous electrolyte solution may be impregnated into the separator and held to form the electrolyte layer.

  As the non-aqueous solvent, non-aqueous solvents known as non-aqueous solvents for non-aqueous electrolytes of lithium-air batteries can be used. Among these, linear ethers such as tetraethylene glycol dimethyl ether may be used as the solvent. This is because the chain ether is less likely to cause side reactions other than the oxidation-reduction reaction of oxygen in the positive electrode, as compared with the carbonate-based solvent.

The electrolyte layer may further contain a compound that functions as a redox mediator, which promotes decomposition or precipitation of Li ₂ O ₂ . An example of a compound that functions as a redox mediator is a derivative of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO). When the electrolyte layer is a solution system, that is, an electrolyte solution, the electrolyte solution is also contained in the pores of the porous body of the positive electrode layer. Therefore, a compound that functions as a redox mediator may be contained in the pores of the porous body of the positive electrode layer.

5. Battery Case The battery case of the lithium-air battery according to the present embodiment is not particularly limited, as long as it can accommodate the positive electrode, the negative electrode, and the electrolyte layer described above. Therefore, the battery case of the air battery of the present embodiment is not limited to the battery case 11 shown in FIG. 1, and various battery cases such as coin type, flat type, cylindrical type and laminate type may be used. . The battery case may be an open-air battery case, but may be a closed battery case. Note that the open-air battery case has a vent that allows the atmosphere to enter and exit, and is a case in which the atmosphere can be in contact with the positive electrode. On the other hand, in the case of the sealed battery case, the sealed battery case may be provided with a gas (air) supply pipe and a discharge pipe. In this case, the gas supplied and discharged may be a dry gas. The gas may have a high oxygen concentration or may be pure oxygen (99.99%). In addition, the oxygen concentration may be increased during discharge and may be reduced during charge.

  As described above, in the present embodiment, the case where the air battery is a lithium air battery is described in detail as an example, but the air battery of the present disclosure includes other metals such as a sodium air battery and a magnesium air battery. Can also be applied to air batteries.

  Hereinafter, the present disclosure will be described in more detail by way of examples. The following embodiment is an example, and the present disclosure is not limited to the following embodiment.

Example 1-1
As a material for forming a porous body containing carbon, "Ketjen Black EC600JD" manufactured by Lion Specialty Chemicals Co., Ltd. was used. This ketjen black, "Nyukol 1308-FA (90)" manufactured by Nippon Emulsifier Co., Ltd., which is a surfactant solution, and "fumaric acid" manufactured by Nippon Shokubai Co., Ltd. as a sublimable powder having a function of pore forming agent And mixed to obtain a mixture. In addition, fumaric acid was ground into powder form beforehand by a jet mill and used as a sublimable powder. The mass ratio of ketjen black to sublimable powder was 7.7: 33 (Ketjen black: sublimable powder). After cooling the obtained mixture, “Fluon® PTFE AD AD911E” manufactured by Asahi Glass Co., Ltd. was added to the mixture as a binder, and the mixture was stirred again. The binder was added such that the mass ratio of ketjen black to binder was 7: 3 (ketjen black: binder). The obtained mixture was rolled by a roll press to produce a sheet. The obtained sheet was fired at 320 ° C. in a firing furnace to remove moisture, surfactant and sublimable powder. The sheet was rolled again by a roll press, adjusted to a thickness of 200 μm, and used as a positive electrode layer, and a SUS304 mesh (manufactured by Niraco Co., Ltd.) attached to this positive electrode layer as a positive electrode current collector was used as a positive electrode. The pore size distribution of this sheet was determined by the method described later. Further, the first pore volume and the second pore volume were also determined from the obtained pore size distribution. As a non-aqueous electrolytic solution, a solution obtained by dissolving LiTFSA (lithium bis trifluoromethane sulfonylamide, manufactured by Kishda Chemical Co., Ltd.) as an electrolyte in tetraethylene glycol dimethyl ether (TEGDME, manufactured by Kishda Chemical Co., Ltd.) which is a non-aqueous solvent was used. This non-aqueous electrolytic solution was obtained by adding LiTFSA to TEGDME to a concentration of 1 mol / L and stirring and mixing and dissolving it overnight in a dry air atmosphere having a dew point of −50 ° C. or less. A glass fiber separator was used as the separator. A metal lithium (made by Honso Chemical Co., Ltd.) was used as a negative electrode layer, and a SUS304 mesh attached to this negative electrode layer as a negative electrode current collector was used as a negative electrode. The positive electrode, the separator, the non-aqueous electrolyte and the negative electrode were arranged as shown in FIG. 1 to produce an air battery. The discharge test was done about the produced air battery. After the test, the battery was disassembled, the thickness of the positive electrode was measured, and the expansion coefficient of the positive electrode was measured. The expansion coefficient of the positive electrode was calculated based on the thickness of the sheet before the test. The volumetric energy density was calculated using the apparent capacity per volume of the positive electrode calculated using the apparent volume of the positive electrode measured after the discharge test and the average discharge voltage. As a result of the first pore volume and the second pore volume of the sheet produced as the positive electrode layer, the expansion coefficient and volume energy density of the positive electrode are shown in Table 1 as a result of the discharge test of the air battery.

(Example 1-2)
A positive electrode (positive electrode layer) and an air battery were produced in the same manner as in Example 1-1 except that the amount of the sublimable powder was reduced. Specifically, the mass ratio of ketjen black to the sublimable powder was set to 7.7: 22 (Ketjen black: sublimable powder). As a result of the first pore volume and the second pore volume of the sheet produced as the positive electrode layer, the expansion coefficient and volume energy density of the positive electrode layer are shown in Table 1 as a result of the discharge test of the air battery.

(Example 1-3)
A positive electrode (positive electrode layer) and an air battery were produced in the same manner as in Example 1-1 except that the amount of the sublimable powder was reduced. Specifically, the mass ratio of ketjen black to sublimable powder is set to 7: 5 (Ketjen black: sublimation powder). As a result of the first pore volume and the second pore volume of the sheet produced as the positive electrode layer, the expansion coefficient and volume energy density of the positive electrode layer are shown in Table 1 as a result of the discharge test of the air battery.

(Comparative Example 1-1)
A positive electrode (positive electrode layer) and an air battery were produced in the same manner as in Example 1-1 except that no sublimable powder was added. As a result of the first pore volume and the second pore volume of the sheet produced as the positive electrode layer, the expansion coefficient and volume energy density of the positive electrode layer are shown in Table 1 as a result of the discharge test of the air battery.

(Example 2-1)
As materials for forming a porous body containing carbon, “Ketjen Black EC600JD” manufactured by Lion Specialty Chemicals Co., Ltd. and “porous carbon Knovel C Novel L (3) 010” manufactured by Toyo Carbon Co., Ltd. were used. Ketjen black, Knobel, "Nycor 1308-FA (90)" made by Nippon Emulsifier Co., Ltd., which is a surfactant solution, and "Fumaru made by Nippon Shokuhin Co., Ltd. as a sublimable powder having a function of pore forming agent The acid was mixed and stirred to obtain a mixture. In addition, fumaric acid was ground into powder form beforehand by a jet mill and used as a sublimable powder. The mass ratio of ketjen black, Knobel and sublimable powder was 4.4: 3.3: 33 in this order. After cooling the obtained mixture, “Fluon® PTFE AD AD911E” manufactured by Asahi Glass Co., Ltd. was added to the mixture as a binder, and the mixture was stirred again. The binder was added such that the mass ratio of ketjen black, Knobel and the binder was 4: 3: 3 in this order. The obtained mixture was rolled by a roll press to produce a sheet. The obtained sheet was fired at 320 ° C. in a firing furnace to remove moisture, surfactant and sublimable powder. The sheet was rolled again by a roll press and adjusted to a thickness of 200 μm to obtain a positive electrode layer. For this positive electrode layer, the volume resistivity of the positive electrode layer and the pore size distribution in the direction parallel to the main surface measured on the main surface of the positive electrode layer were determined by the method described later. Hereinafter, “the volume resistivity of the positive electrode layer in the direction parallel to the main surface measured on the main surface of the positive electrode layer” will be referred to as “the volume resistivity of the positive electrode layer”. Further, the first pore volume and the second pore volume were also determined from the obtained pore size distribution. What attached SUS304 mesh (made by Niraco Co., Ltd.) as a positive electrode current collector to this positive electrode layer was used as a positive electrode. As a non-aqueous electrolytic solution, a solution obtained by dissolving LiTFSA (lithium bis trifluoromethane sulfonylamide, manufactured by Kishda Chemical Co., Ltd.) as an electrolyte in tetraethylene glycol dimethyl ether (TEGDME, manufactured by Kishda Chemical Co., Ltd.) which is a non-aqueous solvent was used. This non-aqueous electrolytic solution was obtained by adding LiTFSA to TEGDME to a concentration of 1 mol / L and stirring and mixing and dissolving it overnight in a dry air atmosphere having a dew point of −50 ° C. or less. A glass fiber separator was used as the separator. A metal lithium (made by Honso Chemical Co., Ltd.) was used as a negative electrode layer, and a SUS304 mesh attached to this negative electrode layer as a negative electrode current collector was used as a negative electrode. The positive electrode, the separator, the non-aqueous electrolyte and the negative electrode were arranged as shown in FIG. 1 to produce an air battery. The discharge test was done about the produced air battery. After the test, the battery was disassembled, the thickness of the positive electrode was measured, and the expansion coefficient of the positive electrode was measured. The expansion coefficient of the positive electrode was calculated based on the thickness of the sheet before the test. The volumetric energy density was calculated using the apparent capacity per volume of the positive electrode calculated using the apparent volume of the positive electrode measured after the discharge test and the average discharge voltage. As a result of the first pore volume and the second pore volume of the sheet produced as the positive electrode layer, the volume resistivity of the positive electrode layer, the result of the discharge test of the air battery, and the volumetric energy density are shown in Table 1. The amount of surface functional groups of carbon contained in the porous body constituting the positive electrode layer is calculated by determining the amounts of surface functional groups of ketjen black and Knobel used as the material for forming the porous body by the method described later. It was done. The amount of surface functional groups is also shown in Table 2.

(Example 2-2)
A positive electrode was prepared in the same manner as in Example 2-1, except that no sublimable powder was added, and the mass ratio of ketjen black, Knobel and binder was changed to 1: 6: 3 in this order. (Positive electrode layer) and an air battery were produced. As a result of the first pore volume and the second pore volume of the sheet prepared as the positive electrode layer, the volume resistivity of the positive electrode layer, the surface functional group amount of carbon, the result of the discharge test of the air cell, and the volume energy density are shown in FIG. Shown in 2.

(Example 2-3)
A positive electrode was prepared in the same manner as in Example 2-1, except that no sublimable powder was added, and the mass ratio of ketjen black, Knobel and binder was changed to 4: 3: 3 in this order. (Positive electrode layer) and an air battery were produced. As a result of the first pore volume and the second pore volume of the sheet prepared as the positive electrode layer, the volume resistivity of the positive electrode layer, the surface functional group amount of carbon, the result of the discharge test of the air cell, and the volume energy density are shown in FIG. Shown in 2.

(Example 2-4)
A positive electrode was prepared in the same manner as in Example 2-1, except that no sublimable powder was added, and the mass ratio of ketjen black, Knobel and binder was changed to 6: 1: 3 in this order. (Positive electrode layer) and an air battery were produced. As a result of the first pore volume and the second pore volume of the sheet prepared as the positive electrode layer, the volume resistivity of the positive electrode layer, the surface functional group amount of carbon, the result of the discharge test of the air cell, and the volume energy density are shown in FIG. Shown in 2.

(Example 2-5)
A positive electrode (positive electrode layer) was prepared in the same manner as in Example 2-1, except that ketjen black and sublimable powder were not added, and the mass ratio between the Knobel and the binder was changed to 7: 3 in this order. And an air battery. As a result of the first pore volume and the second pore volume of the sheet prepared as the positive electrode layer, the volume resistivity of the positive electrode layer, the surface functional group amount of carbon, the result of the discharge test of the air cell, and the volume energy density are shown in FIG. Shown in 2.

(Example 2-6)
The mass ratio of ketjen black to sublimable powder was changed to 7.7: 33 in this order without adding KNOBEL, and the mass ratio of ketjen black to binder was changed to 7: 3 in this order A positive electrode (positive electrode layer) and an air battery were produced in the same manner as in Example 2-1 except for the above. As a result of the first pore volume and the second pore volume of the sheet prepared as the positive electrode layer, the volume resistivity of the positive electrode layer, the surface functional group amount of carbon, the result of the discharge test of the air cell, and the volume energy density are shown in FIG. Shown in 2.

(Example 2-7)
The mass ratio of ketjen black to sublimable powder was changed to 7.7: 22 in this order without adding KNOBEL, and the mass ratio of ketjen black to binder was changed to 7: 3 in this order A positive electrode (positive electrode layer) and an air battery were produced in the same manner as in Example 2-1 except for the above. As a result of the first pore volume and the second pore volume of the sheet prepared as the positive electrode layer, the volume resistivity of the positive electrode layer, the surface functional group amount of carbon, the result of the discharge test of the air cell, and the volume energy density are shown in FIG. Shown in 2.

(Comparative example 2-1)
A positive electrode (positive electrode layer) was prepared in the same manner as in Example 2-1, except that KNOBELL and sublimable powder were not added, and the mass ratio of ketjen black to binder was changed to 7: 3 in this order. And an air battery. As a result of the first pore volume and the second pore volume of the sheet prepared as the positive electrode layer, the volume resistivity of the positive electrode layer, the surface functional group amount of carbon, the result of the discharge test of the air cell, and the volume energy density are shown in FIG. Shown in 2.

  The pore diameter distribution of the sheet produced as the positive electrode layer, the method of measuring the first pore volume and the second pore volume, the method of measuring the volume resistivity of the positive electrode layer, and the positive electrode layer, which were carried out in Examples and Comparative Examples The method of measuring the amount of surface functional groups of carbon contained in the porous body, the test method of the discharge test of the air battery, and the method of calculating the volumetric energy density will be specifically described below. In addition, the volume resistivity of a positive electrode layer and the surface functional group amount of carbon contained in a porous body were measured only with respect to Examples 2-1 to 2-7 and Comparative Example 2-1.

(Pore size distribution, first pore volume and second pore volume)
The mercury porosimetry measurement was performed about the sheet | seat produced as a positive electrode layer, and 1st pore volume and 2nd pore volume were calculated | required with pore diameter distribution.

(Discharge test)
After holding the air battery in an oxygen atmosphere for 20 minutes or more, a discharge test was performed with a current density of 0.1 mA / cm ² and a discharge cut voltage of 2.0 V. In addition, discharge capacity is shown by the capacity | capacitance per unit mass of the sheet | seat produced as a positive electrode layer.

(Volume resistivity of positive electrode layer)
The volume resistivity of the positive electrode layer was measured using a low resistivity meter (MCP-T610) and a four-point probe (ECP probe) manufactured by Mitsubishi Chemical Analytech Co., Ltd. for the sheet produced as the positive electrode layer. The volume resistivity of the positive electrode layer was measured on the main surface of the positive electrode layer.

(Surface functional group amount)
The amount of surface functional groups of carbon contained in the porous body of the positive electrode layer was calculated using the measured values of the amounts of surface functional groups of ketjen black and Knobel used in the preparation of the porous body. With respect to each of ketjen black and Knobel, back titration with a sodium hydroxide solution was carried out using an automatic titrator made by Kyoto Denshi Kogyo Co., Ltd. under the conditions where hydrochloric acid was added under an inert atmosphere according to the Boehm method. The surface functional group content of each of ketjen black and Knobel was measured by determining the total acid functional group content from the consumption of sodium hydroxide described above. The surface functional group amount of carbon in each Example and Comparative Example is calculated from the ratio of ketjen black and Knobel in each Example and Comparative Example using the surface functional group amount of Ketjen black and the surface functional group amount of Knovel did.

(Volume energy density)
The average value of the voltages measured from the start to the end of the discharge test is taken as the average discharge voltage. After the discharge test, the thickness and the area of the positive electrode were measured using a thickness gauge. A value obtained by multiplying the measured thickness of the positive electrode by the area is calculated as an apparent volume of the positive electrode. As the apparent volume of the positive electrode, a volume A determined only from the thickness of the positive electrode layer and a volume B determined from the sum of the thickness of the positive electrode current collector layer and the thickness of the positive electrode layer were used. That is, the volume A was the apparent volume of only the positive electrode layer, and the volume B was the apparent volume of the positive electrode current collector layer and the positive electrode layer. The value obtained by dividing the discharge capacity obtained by the above-described discharge test by the apparent volume (volume A or volume B) of the above-described positive electrode was calculated as the discharge capacity (mAh / cm ³ ) per apparent volume of the positive electrode. . The volume energy density (Wh / L) was calculated by multiplying the average discharge voltage (V) and the apparent discharge capacity per volume of the positive electrode (mAh / cm ³ ). Tables 1 and 2 show both the volume energy density A calculated with the volume A as the apparent volume of the positive electrode and the volume energy density B calculated with the volume B as the apparent volume of the positive electrode .

  As understood from the results shown in Table 1, in the air battery of Comparative Example 1-1, the expansion coefficient of the positive electrode was large, and the volumetric energy density was low. Moreover, in the air battery of Comparative Example 1-1, the discharge capacity was also low.

  On the other hand, in the air batteries of Examples 1-1 to 1-3, the expansion coefficient of the positive electrode was suppressed as the second pore volume increased, and the discharge capacity and the volumetric energy density were improved. From this result, the air batteries of Examples 1-1 to 1-3 including the positive electrode including the porous body having the second pore volume larger than the first pore volume as the positive electrode layer have high discharge capacity and high It was found to have both volume energy density.

  Similar to the results of Examples 1-1 to 1-3 and Comparative Example 1-1, an example including a positive electrode including a porous body having a larger second pore volume than the first pore volume as a positive electrode layer. The air batteries of 2-1 to 2-7 were found to have both higher discharge capacity and higher volume energy density than the air battery of Comparative Example 2-1.

  In the porous bodies of the positive electrodes of Examples 2-1 to 2-4, the second pore volume is larger than the first pore volume, and the surface functional group content of carbon contained is 0.3 mmol / g or more 1 .4 mmol / g or less. Furthermore, in the positive electrode of Examples 2-1 to 2-4, the volume resistivity of the positive electrode layer was suppressed to 5126 mOhm · cm or less. As shown in Table 2, the air batteries of Examples 2-1 to 2-4 equipped with such a positive electrode were able to achieve both high discharge capacity and high volume energy density at a high level.

  Comparing the positive electrodes of Examples 2-1 to 2-4, assuming that the first pore volume is V1 and the second pore volume is V2, the positive electrode having a larger V2 / V1 has higher volume energy density. Was.

  In the porous body of the positive electrode of Example 2-5, the second pore volume was larger than the first pore volume. However, in the positive electrode of Example 2-5, the surface functional group amount of carbon contained in the porous body was as large as 1.53 mmol / g and was outside the range of 0.3 mmol / g or more and 1.4 mmol / g or less . Moreover, the volume resistivity of the positive electrode layer of the positive electrode of Example 2-5 was higher than the positive electrode layer of Examples 2-1 to 2-4. Although the air battery of Example 2-5 provided with such a positive electrode has high discharge capacity, the volumetric energy density was lower than the air battery of Examples 2-1 to 2-4.

  In the porous bodies of the positive electrodes of Examples 2-6 and 2-7, the second pore volume was larger than the first pore volume. However, in the positive electrodes of Examples 2-6 and 2-7, the amount of surface functional groups of carbon contained in the porous body is as small as 0.19 mmol / g, which is out of the range of 0.3 mmol / g to 1.4 mmol / g. Met. Although the air batteries of Examples 2-6 and 2-7 provided with such a positive electrode have high discharge capacity, their volumetric energy density is lower than that of the air batteries of Examples 2-1 to 2-4. The

  The porous body of the positive electrode of Comparative Example 2-1 had a second pore volume smaller than the first pore volume. Furthermore, in the positive electrode of Comparative Example 2-1, the amount of surface functional groups of carbon contained in the porous body was as small as 0.19 mmol / g and was outside the range of 0.3 mmol / g to 1.4 mmol / g. . Although the air battery of Comparative Example 2-1 provided with such a positive electrode has a relatively high discharge capacity, its volumetric energy density is very low.

  As described above, from the results shown in Table 2, the second pore volume is larger than the first pore volume, and the amount of surface functional groups of carbon contained is 0.3 mmol / g or more and 1.4 mmol / g or less It has been found that an air battery comprising a positive electrode comprising a porous body in the range as a positive electrode layer can realize both high discharge capacity and high volume energy density at a high level.

  The air battery of the present disclosure has high discharge capacity and high volumetric energy density. Thus, the air battery of the present disclosure is useful as a high capacity battery.

DESCRIPTION OF SYMBOLS 1 air battery 11 battery case 11a cylindrical part 11b bottom part 11c lid part 12 negative electrode 12a negative electrode layer 12b negative electrode collector 13 positive electrode layer 13b positive electrode collector 14 electrolyte layer 15 air intake hole

Claims (12)

A positive electrode for an air battery comprising a porous body containing carbon, wherein
The porous body includes a first pore having a pore size of 4 nm or more and less than 100 nm, and a second pore having a pore size of 100 nm or more and 10 μm or less,
In the porous body, a second pore volume which is a cumulative pore volume of the second pores is larger than a first pore volume which is a cumulative pore volume of the first pores,
Positive electrode for air battery. The sum of the second pore volume and the first pore volume is less 2.6 cm ³ / g or more 4.0 cm ³ / g,
The positive electrode for an air battery according to claim 1. The second pore volume is 1.4 cm ³ / g or more and 3.0 cm ³ / g or less.
The air battery positive electrode according to claim 1. The surface functional group amount of the carbon contained in the porous body is 0.3 mmol / g or more and 1.4 mmol / g or less.
The air battery positive electrode according to any one of claims 1 to 3. The surface functional group amount of the carbon contained in the porous body is 0.38 mmol / g or more and 1.34 mmol / g or less.
The air battery positive electrode according to claim 4. The air battery positive electrode includes a positive electrode layer that can be oxidized and reduced using oxygen in air as a positive electrode active material,
The porous body is contained in the positive electrode layer,
The volume resistivity of the positive electrode layer in the direction parallel to the main surface measured on the main surface of the positive electrode layer is 5500 mOhm · cm or less.
The air battery positive electrode according to any one of claims 1 to 5. The volume resistivity is 2500 mOhm cm or less.
The air battery positive electrode according to claim 6. Assuming that the first pore volume is V1 and the second pore volume is V2, 1.4 ≦ V2 / V1 is satisfied.
The air battery positive electrode according to any one of claims 1 to 7. The V1 and the V2 satisfy 1.5 ≦ V2 / V1.
The air battery positive electrode according to claim 8. The V1 and the V2 satisfy 2.5 ≦ V2 / V1.
The air battery positive electrode according to claim 9. The V1 and the V2 satisfy 3 ≦ V2 / V1.
The air battery positive electrode according to claim 10. The air battery positive electrode according to any one of claims 1 to 11,
An anode capable of absorbing and desorbing metal ions;
An electrolyte layer disposed between the positive electrode and the negative electrode;
An air battery equipped with

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