Porous carbon particle for forming porous carbon film used for positive electrode of air battery, porous carbon film for positive electrode of air battery, and air battery

Abstract

Porous carbon particles for forming a porous carbon film used for a positive electrode of an air battery according to one embodiment of the present invention satisfy all of a) to g).　a) The half width of a D-band peak in a Raman spectrum is 30-60 cm-1.　b) The half width of a G-band peak in the Raman spectrum is 32-80 cm-1.　c) An R value, which is the ratio of the intensity of the D-band peak to the intensity of the G-band peak in the Raman spectrum, is 0.8 or more.　d) A plane spacing d002 of the (002) plane of carbon determined by X-ray diffraction (XRD) has a portion of 0.336-0.355 nm.　e) The volume of pores having a diameter of 1-1000 nm determined by a BJH method from an adsorption isotherm obtained by a nitrogen adsorption method is 1.5-10.0 cm3 / g.　f) The volume of pores having a diameter of 1-100 nm determined by the BJH method from the adsorption isotherm obtained by the nitrogen adsorption method is 1.0-8.0 cm3 / g.　g) The specific surface area determined by the BET method from the adsorption isotherm obtained by the nitrogen adsorption method is 500-2000 cm2 / g.

Description

Porous carbon particles for forming porous carbon membranes used in positive electrodes of air batteries, porous carbon membranes for positive electrodes of air batteries, and air batteries

[0001] The present invention relates to porous carbon particles for forming a porous carbon membrane used in a positive electrode of an air battery, a porous carbon membrane for a positive electrode of an air battery, and an air battery.

[0002] Batteries are gaining attention as the driving force behind a smart society, and demand for them is rapidly increasing. There are many different types of batteries, but air batteries are attracting particular attention as they are small, lightweight, and offer large capacity.

[0003] [Correction based on Rule 91 12.11.2024] An air battery is a battery that uses oxygen from the air as the positive electrode active material and a metal as the negative electrode active material. It is also called a metal-air battery and is classified as a type of fuel cell. A representative example is a lithium-air battery, which uses a metal or compound that can absorb and release lithium ions as the negative electrode active material. The reaction at each electrode in a lithium-air battery is expressed by the following formula: Negative electrode: 2Li ⇔ 2Li ＋ +2e － Positive electrode: 2Li ＋ +O ２ +2e － ⇔Li ２ O ２

[0004] In air batteries, the positive electrode active material is oxygen in the air, and the positive electrode active material can be supplied from outside the battery, so the battery can be made small and lightweight, and it can be said that its structure is suitable for large capacity.

[0005] Various efforts have been made to improve the performance of air batteries, and the following have been reported regarding the materials constituting the positive electrode.

[0006] Patent Document 1 discloses an air battery having a positive electrode mainly made of a carbonaceous material having a pore volume of 1.0 ml / g or more occupied by pores with a diameter of 1 nm or more. In Example 1, the carbonaceous material has a pore volume of 2.15 ml / g occupied by pores with a diameter of 1 nm or more and a BET specific surface area of ​​1350 m ２The article mentions the use of Ketjen Black EC600JD, which has a discharge capacity of 2450 mAh / g, and describes that when this carbonaceous material is mixed with a binder, formed into a sheet, and used as a positive electrode, the air battery exhibits a discharge capacity of 2450 mAh / g.

[0007] Patent Document 2 describes that, with regard to porous carbon used in the positive electrode of a metal-air battery, the ratio of pores having a pore diameter of 20 nm or more to the total pore volume is preferably 70% or more, and that the pore volume occupied by pores of 1 nm or more is preferably 1 ml / g or more. It also describes that in Example 1, a high capacity was maintained even after five charge / discharge cycles (capacity retention rate: 60%).

[0008] Patent Document 3 relates to a porous carbon structure used in the positive electrode of an air battery, and describes a novel method using Ketjen Black (registered trademark) as the raw porous carbon particles, in which the pore volume occupied by pores with a diameter of 1 nm or more and 200 nm or less is 1.2 cm ３ / g or more, 7.0cm ３ / g or less, and the pore volume occupied by pores with a diameter of 1 nm or more and 1000 nm or less is 2.3 cm ３ / g or more, 10.0cm ３ It is described that a porous carbon structure having a porosity of 0.1 to 1.0 g or less was prepared and used as a positive electrode, thereby obtaining an air battery with a large discharge capacity.

[0009] JP 2002-15737 A JP 2015-76125 A International Publication No. 2020 / 235638 JP 2012-188309 A

[0010] As shown in Patent Documents 1 to 3, various technical studies have led to progress in improving the discharge capacity of air batteries. However, for use as secondary batteries, it is also necessary to minimize the decrease in discharge capacity due to repeated charge and discharge, i.e., to have excellent cycle characteristics. Patent Document 1 describes the discharge capacity at the third cycle as an improvement in discharge capacity, but does not mention any measures regarding the number of cycles beyond that, i.e., the number of cycles that can be repeated. Patent Document 2 reports that the capacity retention rate after five charge and discharge cycles is only 60%. Patent Document 3 does not provide any specific description regarding cycle characteristics. As such, conventional air batteries have not been sufficient for practical use in terms of cycle characteristics.

[0011] In view of the above problems, an object of the present invention is to provide an air battery having a large discharge capacity and excellent cycle characteristics.

[0012] The present inventors have conducted extensive research to solve the above problems, and have found that an air battery with excellent cycle characteristics can be obtained by employing porous carbon particles having specific structures and physical properties as a constituent material of a porous carbon membrane used as a positive electrode of an air battery, and by specifying the structure and physical properties of the membrane, and have completed the present invention.

[0013] That is, the present invention includes the following aspects: [1] Porous carbon particles for forming a porous carbon membrane used for a positive electrode of an air battery, which satisfy all of the following a) to g): a) a half-width of a D-band peak in a Raman spectrum of 30 cm －１ 60cm or more －１ b) The half-width of the G-band peak in the Raman spectrum is 32 cm or less. －１ 80cm or more －１ c) The R value, which is the ratio of the D band peak intensity to the G band peak intensity in a Raman spectrum, is 0.8 or more. d) The lattice spacing d of the (002) plane of carbon measured by X-ray diffraction (XRD) is 0.8 or more. ００２e) The volume of pores with diameters of 1 nm or more and 1000 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 1.5 cm ３ / g or more 10.0cm ３ f) The volume of pores having a diameter of 1 nm or more and 100 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 1.0 cm ３ / g or more 8.0cm ３ g) The specific surface area determined by the BET method from an adsorption isotherm obtained by a nitrogen adsorption method is 500 cm ２ / g or more 2000cm ２ [2] A porous carbon membrane for a positive electrode of an air battery, comprising the porous carbon particles according to aspect [1] and satisfying all of the following A) to D): A) the half-width of the D band peak in the Raman spectrum is 64 cm －１ B) The volume of pores having a diameter of 1 nm or more and 1000 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is less than 1.2 cm ３ / g or more 8.0cm ３ C) The volume of pores having a diameter of 1 nm or more and 100 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 0.8 cm ３ / g or more 7.0cm ３ / g or less. D) The specific surface area calculated by the BET method from the adsorption isotherm obtained by the nitrogen adsorption method is 400 cm ２ / g or more 2000cm ２ [3] A) The half width of the D band peak in the Raman spectrum is 37 cm －１ [4] The porous carbon membrane according to aspect [2], wherein the apparent density is 0.10 g / cm or more. ３ 0.20cm or more ３ [5] The porous carbon membrane of any one of aspects [2] to [4], having a porosity of 85% or more and 99% or less. [6] An air battery comprising the porous carbon membrane of any one of aspects [2] to [5] in a positive electrode.

[0014] According to the present invention, it is possible to provide an air battery having a large discharge capacity and excellent cycle characteristics.

[0015] 1 is a flowchart showing a manufacturing process of a porous carbon membrane for a positive electrode of an air battery according to one aspect (second aspect) of the present invention. 2 is a cross-sectional schematic diagram showing an example of the structure of an air battery according to one aspect (third aspect) of the present invention. 3 is a cross-sectional schematic diagram showing an example of the structure of a stacked-type air battery according to one aspect (third aspect) of the present invention. 4 is a diagram explaining a method for determining the half-width of a peak in the Raman spectrum of a porous carbon particle. The spectrum shown is measured for porous carbon particles (KB) according to Comparative Example 8. 5 is an X-ray diffraction chart of porous carbon particles (PC-1) according to Example 1. 6 is a Raman spectrum of porous carbon particles (PC-1) according to Example 1. 7 is a cross-sectional schematic diagram showing the structure of a coin cell (CR2032) for capacity measurement prepared in the Examples and Comparative Examples. 8 is a cross-sectional schematic diagram showing the structure of a cell for evaluating cycle characteristics prepared in the Examples and Comparative Examples. 9 is an X-ray diffraction chart of porous carbon particles (CPC-1) according to Comparative Example 1. 10 is a Raman spectrum of porous carbon particles (CPC-1) according to Comparative Example 1. 1 is an X-ray diffraction chart of porous carbon particles (PC-2) according to Example 2. 2 is an X-ray diffraction chart of porous carbon particles (CPC-2) according to Comparative Example 2. 3 is an X-ray diffraction chart of porous carbon particles (PC-3) according to Example 3. 4 is an X-ray diffraction chart of porous carbon particles (CPC-3) according to Comparative Example 3. 5 is an X-ray diffraction chart of porous carbon particles (PC-4) according to Example 4. 6 is an X-ray diffraction chart of porous carbon particles (PC-5) according to Example 5. 7 is an X-ray diffraction chart of porous carbon particles (CPC-4) according to Comparative Example 4. 8 is an X-ray diffraction chart of porous carbon particles (CPC-4) according to Comparative Example 4. 9 is an X-ray diffraction chart of porous carbon particles (CPC-5) according to Comparative Example 5. 10 is an X-ray diffraction chart of porous carbon particles (CPC-5) according to Comparative Example 5. 1 is an X-ray diffraction chart of porous carbon particles (CPC-6) according to Comparative Example 6. 2 is a Raman spectrum of porous carbon particles (CPC-6) according to Comparative Example 6. 3 is an X-ray diffraction chart of porous carbon particles (PC-8) according to Example 8.1 is an X-ray diffraction chart of porous carbon particles (CPC-7) according to Comparative Example 7. FIG. 2 is an X-ray diffraction chart of porous carbon particles (KB) according to Comparative Example 8.

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description, like elements are given like numbers and repeated explanations will be omitted. Note that the present invention is not limited to these embodiments.

[0017] <Porous Carbon Particles> a) Half-Width of D-Band Peak in Raman Spectrum Porous carbon particles for forming a porous carbon membrane used in a positive electrode of an air battery according to one aspect of the present invention (hereinafter, may be referred to as "porous carbon particles according to the first aspect") have a half-width of D-band peak in Raman spectrum of 30 cm or less. －１ 60cm or more －１ When the half-width of the D-band peak in the Raman spectrum is within the above range, an air battery having good cycle characteristics can be obtained. This is presumably due to the following mechanism of action.

[0018] In the Raman spectrum of carbon, a peak called the G-band peak, which is usually due to the crystallinity of carbon, appears at 1600 cm －１ A peak called the D-band peak, which is due to crystal disorder, appears near 1350 cm －１ Both the G-band peak and the D-band peak become sharper as the crystallinity of carbon increases, and their half-widths, i.e., the peak width at the position where the intensity is half of the maximum value, become smaller. The half-width of the D-band peak, which is due to the crystal disorder, is 60 cm －１ On the other hand, carbon with a half-width of the D-band peak of 30 cm or more has a very low crystallinity and contains a large amount of crystal disorder. －１ Carbon with a D-band peak width of less than 30 cm has a fairly high crystallinity and little crystal disorder. －１ 60cm or more －１ The porous carbon particles according to the first aspect described below can be said to have an appropriate amount of crystal disorder.

[0019] In lithium-air batteries equipped with a porous carbon membrane on the positive electrode, the reaction that occurs at the positive electrode during discharge is that lithium ions migrating from the negative electrode and oxygen migrating and diffusing from the external atmosphere receive electrons from the inner surface of the carbon pores, generating lithium peroxide within the pores. In this case, a positive electrode with a larger pore volume is preferable because it can store more lithium peroxide and produce a battery with a large discharge capacity. However, since a larger pore volume means a larger area of ​​carbon participating in the reaction, a positive electrode with a larger pore volume is undesirable because it is more likely to cause decomposition of the electrolyte due to the reaction between the electrolyte and oxygen. In this case, if the carbon crystals forming the inner surface of the pores are too disordered, the reaction between the electrolyte and oxygen is further promoted, facilitating decomposition of the electrolyte, and the electrolyte is quickly lost, resulting in a decrease in discharge capacity with a small number of charge-discharge cycles. In contrast, if the half-width of the D-band peak in the Raman spectrum is 60 cm or less, the discharge capacity will decrease. －１ When a porous carbon membrane is formed using porous carbon particles having an insufficient amount of crystal disorder as described below and the porous carbon membrane is used in the positive electrode of a lithium-air battery, decomposition of the electrolyte solution caused by the reaction between the electrolyte solution and oxygen is suppressed, and thereby a decrease in discharge capacity due to repeated charge and discharge is suppressed.

[0020] On the other hand, in a positive electrode containing porous carbon particles with too high crystallinity, the affinity between the pore inner surface of the porous carbon particles and the electrolyte is low, making it difficult for the electrolyte to remain on the pore inner surface, resulting in a decrease in discharge capacity after a small number of charge-discharge cycles. －１ In the case of a porous carbon membrane using porous carbon particles having a certain degree of crystal disorder as described above, when this is used as a positive electrode of a lithium-air battery, the affinity between the inner surfaces of the pores and the electrolyte is increased, thereby suppressing a decrease in discharge capacity due to repeated charge and discharge.

[0021] From the above, in the porous carbon particles according to the first aspect, the half width of the D band peak in the Raman spectrum is 30 cm －１ 60cm or more －１ In order to further improve the cycle characteristics of the air battery, the half width of the D band peak is set to 35 cm or less. －１ Over 55cm－１ It is preferable that:

[0022] b) Half-width of G-band peak in Raman spectrum The porous carbon particles according to the first aspect have a half-width of G-band peak in Raman spectrum of 32 cm －１ 80cm or more －１ When the half-width of the G-band peak in the Raman spectrum is within the above range, an air battery having good cycle characteristics can be obtained. This is presumably due to the following mechanism of action.

[0023] From the relationship between the half-width of the peak in the Raman spectrum and the crystallinity of carbon described above, it is found that the half-width of the G band peak in the Raman spectrum is 32 cm －１ 80cm or more －１ The crystallinity of carbon having a half-width of 80 cm or less is －１ It is higher than those exceeding 32 cm －１ It is lower than those below.

[0024] When porous carbon particles having too low crystallinity, i.e., too high amorphousness, are formed into a porous carbon film containing the particles and used as the positive electrode of a lithium-air battery, the electrolyte tends to react with oxygen on the surface of the porous carbon particles, which leads to the decomposition of the electrolyte. As a result, the electrolyte is quickly reduced, resulting in a decrease in discharge capacity with a small number of charge-discharge cycles. In contrast, when the half-width of the G-band peak in the Raman spectrum is 80 cm －１ When a porous carbon membrane is formed using the following porous carbon particles having a crystallinity that is not too low and the porous carbon membrane is used in the positive electrode of a lithium-air battery, decomposition of the electrolyte solution caused by the reaction between the electrolyte solution and oxygen is suppressed, and thereby a decrease in discharge capacity due to repeated charge and discharge is suppressed.

[0025] On the other hand, when porous carbon particles with too high crystallinity and too low amorphousness are used in a positive electrode of a lithium-air battery by forming a porous carbon membrane containing the particles, the electrolyte is less likely to remain on the inner surface of the pores due to the low affinity between the inner surface of the pores of the porous carbon and the electrolyte, and the discharge capacity decreases with a small number of charge-discharge cycles. －１ In the case of a porous carbon membrane using porous carbon particles having a certain degree of crystal disorder as described above, when this is used as a positive electrode of a lithium-air battery, the affinity between the inner surfaces of the pores and the electrolyte is increased, thereby suppressing a decrease in discharge capacity due to repeated charge and discharge.

[0026] From the above, in the porous carbon particles according to the first aspect, the half width of the G band peak in the Raman spectrum is 32 cm －１ 80cm or more －１ In order to further improve the cycle characteristics of the air battery, the half width of the G band peak is set to 35 cm or less. －１ 75cm or more －１ The following is preferred:

[0027] c) Ratio of D-band peak intensity to G-band peak intensity in Raman spectrum (R value) The porous carbon particles according to the first aspect have a G-band peak intensity I Ｇ Intensity of the D band peak I Ｄ The ratio of R value (= I Ｄ / I Ｇ) is 0.8 or more. The higher the crystallinity of the carbon, the smaller the R value, and when it reaches graphite, the R value is 0.02 or less. An R value of 0.8 or more in the Raman spectrum of porous carbon particles indicates that the carbon has moderate amorphousness. This amorphousness increases the affinity between the pore inner surface and the electrolyte when a porous carbon membrane is formed and used as the positive electrode of a lithium-air battery, thereby suppressing the decrease in discharge capacity due to repeated charge and discharge. In contrast, if the R value is less than 0.8, the crystallinity of the carbon becomes too high, i.e., the amorphousness becomes too low, reducing the affinity between the pore inner surface and the electrolyte. This makes it difficult for the electrolyte to remain on the pore surface, resulting in a decrease in discharge capacity with a small number of charge and discharge cycles. In Example 1 of Patent Document 2, the Raman spectrum of a positive electrode (porous carbon membrane) containing mesoporous carbon and a PTFE binder has an R value of about 0.4. The G-band peak and D-band peak in the Raman spectrum of this positive electrode nearly coincide with the peaks obtained for mesoporous carbon in view of the manufacturing method of the positive electrode, and therefore the R value of this mesoporous carbon is outside the range of the present invention, and as a result, the number of cycles remains at a low level of 5 cycles with a capacity retention rate of 60%. From the viewpoint of further improving the cycle characteristics of the air secondary battery, an R value of 1.0 or more is preferable.

[0028] [Rule 91 Amendment 12.11.2024] d) The interplanar spacing d of the (002) plane of carbon measured by X-ray diffraction (XRD) ００２ The porous carbon particles according to the first aspect have a lattice spacing d of the (002) plane of carbon obtained by X-ray diffraction (XRD). ００２ The carbon nanotube has a portion with a thickness of 0.355 nm or less. This results in an air battery with good cycle characteristics. This is presumed to be due to the following mechanism of action. In X-ray diffraction, carbon exhibits a peak at 2θ in the range of 20° to 30°, which is due to the thickness direction of the carbon crystal, i.e., the stacking direction of the carbon network plane. From the value of 2θ at the peak top position, the Bragg equation can be used to calculate the lattice spacing of the carbon network, d ００２The plane spacing of the carbon lattice planes becomes smaller as the crystallinity of carbon increases, i.e., the distance between the carbon lattice planes becomes smaller. When the plane spacing of the carbon lattice planes becomes smaller, the peak top position in X-ray diffraction shifts to a larger value of 2θ (deg), and conversely, when the crystallinity is poor and the distance between the carbon lattice planes is large, the value of 2θ (deg) shifts to a smaller value and the peak becomes broader. The plane spacing d of this (002) plane is ００２ When the interplanar spacing d is 0.355 nm or less, the carbon particles contain a certain amount of crystalline carbon, and when it exceeds 0.355 nm, the carbon particles contain little crystalline carbon. ００２ The smallest value was 0.3354 nm. In lithium-air batteries with a porous carbon membrane on the positive electrode, the reaction that occurs at the positive electrode during discharge is that lithium ions migrating from the negative electrode and oxygen migrating and diffusing from the external atmosphere receive electrons from the inner surface of the carbon pores, generating lithium peroxide within the pores. In this case, a positive electrode with a larger pore volume is preferable because it can store more lithium peroxide and produce a battery with a larger discharge capacity. However, since a larger pore volume means a larger area of ​​carbon participating in the reaction, a positive electrode with a larger pore volume is undesirable because it is more likely to cause decomposition of the electrolyte due to the reaction between the electrolyte and oxygen. In this case, if the crystallinity of the carbon forming the inner surface of the pores is too low, i.e., if it is too amorphous, the reaction between the electrolyte and oxygen is promoted, facilitating decomposition of the electrolyte, accelerating the reduction of the electrolyte, and resulting in a decrease in discharge capacity with a small number of charge-discharge cycles. On the other hand, if a certain amount of crystalline carbon is present, decomposition of the electrolyte due to the reaction between the electrolyte and oxygen is suppressed, and the decrease in discharge capacity due to repeated charge and discharge is suppressed. From the viewpoint of further improving the cycle characteristics of the air battery, the interplanar spacing d ００２ The average particle size is preferably 0.350 nm or less. The lower limit is preferably 0.336 nm or more. If the average particle size is less than this value, the crystallinity becomes too high, the affinity with the electrolyte solution decreases, the electrolyte solution is less likely to remain on the inner surface of the pores, and the discharge capacity decreases with a small number of charge / discharge cycles.

[0029] e) Volume of pores with diameters of 1 nm or more and 1000 nm or less The porous carbon particles according to the first aspect have a volume of pores with diameters of 1 nm or more and 1000 nm or less, which is determined by the BJH (Barrett-Joyner-Hallenda) method from an adsorption isotherm obtained by a nitrogen adsorption method, of 1.5 cm ３ / g or more 10.0cm ３ / g or less. The volume of pores with diameters of 1 nm or more and 1000 nm or less is 1.5 cm ３ / g or more, when a porous carbon film formed using the porous carbon particles is used as the positive electrode of a lithium-air battery, it is possible to store a larger amount of lithium peroxide, which is generated by the reaction of lithium ions with oxygen during discharge, and a lithium-air battery with a large discharge capacity can be obtained. From the viewpoint of obtaining a lithium-air battery with a large discharge capacity, the volume of the pores with a diameter of 1 nm or more and 1000 nm or less is set to 1.6 cm ３ On the other hand, it is preferable that the pore volume occupied by pores having a diameter of 1 nm or more and 1000 nm or less is 10.0 cm ３ / g or less, a decrease in the strength of the porous carbon membrane formed using the porous carbon particles can be suppressed. From the viewpoint of maintaining the strength of the porous carbon membrane, the volume of the pores having a diameter of 1 nm or more and 1000 nm or less is preferably 8.0 cm ３ / g or less is preferable.

[0030] f) Volume of pores with diameters of 1 nm or more and 100 nm or less The porous carbon particles according to the first aspect have a volume of pores with diameters of 1 nm or more and 100 nm or less of 1.0 cm3, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method. ３ / g or more 8.0cm ３ / g or less. The large volume of pores with diameters of 1 nm or more and 100 nm or less means that there are many pores with relatively small diameters. In pores with small diameters, the size of lithium peroxide produced by the reaction of lithium ions and oxygen during discharge of a lithium-air battery is also kept relatively small. Furthermore, such small-sized lithium peroxide, due to its large surface area, is likely to undergo a reaction to separate into lithium ions and oxygen during charging, thereby suppressing a decrease in discharge capacity due to repeated charge and discharge. This effect is achieved when the volume of pores with diameters of 1 nm or more and 100 nm or less in the porous carbon particles constituting the porous carbon membrane is 1.0 cm ３ / g or more, the volume of pores with a diameter of 1 nm or more and 100 nm or less is set to 1.0 cm ３ In order to further suppress the decrease in discharge capacity due to repeated charge and discharge, the volume of pores having a diameter of 1 nm or more and 100 nm or less is set to 1.5 cm ３ On the other hand, it is preferable that the volume of pores with a diameter of 1 nm or more and 100 nm or less is 8.0 cm ３ / g or less, a decrease in the strength of the porous carbon membrane formed using the porous carbon particles can be suppressed. From the viewpoint of maintaining the strength of the porous carbon membrane, the volume of the pores having a diameter of 1 nm or more and 100 nm or less is preferably 7.0 cm ３ / g or less is preferable.

[0031] g) Specific Surface Area The porous carbon particles according to the first aspect have a specific surface area of ​​500 cm2 or less, as determined by the BET method from an adsorption isotherm obtained by a nitrogen adsorption method. ２ / g or more 2000cm ２ / g or less. The specific surface area determined by the BET method is 500 cm ２ / g or more, when a porous carbon film formed using the porous carbon particles is used as the positive electrode of a lithium-air battery, there are more reaction sites for oxygen and lithium ions to receive electrons to become lithium peroxide during discharge, and more reaction sites for lithium peroxide to release electrons to become oxygen and lithium ions during charge, and the discharge reaction and the charge reaction are more likely to proceed. From the viewpoint of promoting the charge-discharge reaction, the specific surface area determined by the BET method is 700 cm ２On the other hand, it is preferable that the specific surface area measured by the BET method is 2000 cm ２ / g or less, a decrease in the strength of the porous carbon membrane formed using the porous carbon particles can be suppressed. From the viewpoint of maintaining the strength of the porous carbon membrane, the specific surface area determined by the BET method is 1700 cm ２ / g or less is preferable.

[0032] <<Method for producing porous carbon particles>> The porous carbon particles according to the first aspect can be produced by, for example, optimizing various conditions in the procedure disclosed in Patent Document 4, in which an organic resin is wet- or dry-mixed in a solution or powder state with oxide particles (template particles), the mixture is subjected to a primary heat treatment in a non-oxidizing atmosphere or a reduced-pressure atmosphere to carbonize the organic resin, and then the oxide is removed by a washing treatment to produce amorphous porous carbon (carbonaceous sintered body), and then this amorphous porous carbon is subjected to a secondary heat treatment in a non-oxidizing atmosphere or a reduced-pressure atmosphere at a temperature equal to or higher than the temperature at which the amorphous porous carbon crystallizes. This production method will be described in detail below.

[0033] <Mixing of Organic Resin and Oxide Particles> First, the organic resin and oxide particles are mixed. The organic resin is used as a constituent material for the carbonaceous walls of the porous carbon particles. Examples of such resins include synthetic resins such as polyvinyl alcohol, aliphatic or aromatic polyester resins, polyolefin resins, acrylic resins, styrene resins, polyamide resins, polyacrylonitrile resins, and elastomers mainly composed of polybutadiene and polyisoprene; thermoplastic resins such as natural rubber and petroleum resins; and thermosetting resins such as phenolic resins, furan resins, epoxy resins, and alkyd resins.

[0034] The oxide particles are mixed with an organic resin and removed after the first heat treatment described below, thereby contributing to the formation of pores in the porous carbon particles. As the oxide forming the oxide particles, an oxide of a Group 2 element in the periodic table can be preferably used because of its ease of removal in the removal step described below. Examples of Group 2 elements include magnesium, calcium, strontium, and barium. Among these, magnesium and calcium are preferred, with magnesium being particularly preferred.

[0035] The crystallite size of the oxide particles is a factor that affects the pore size of the resulting porous carbon particles. The average crystallite size of the oxide particles to obtain the porous carbon particles according to the first aspect is preferably 5 nm or more and 50 nm or less, and more preferably 10 nm or more and 30 nm or less.

[0036] The method for mixing the organic resin and the oxide particles is not particularly limited as long as it can produce a mixture in which both components and any other components that are added optionally are uniformly distributed. Examples of the method include using a general-purpose mixing device such as a mixer equipped with an impeller, blades, or screws, a mixer in which the container itself rotates and revolves, and a ball mill mixer.

[0037] <Primary Heat Treatment> The primary heat treatment is performed by heating a mixture containing an organic resin and oxide particles in a non-oxidizing atmosphere or a reduced pressure atmosphere. The primary heat treatment carbonizes the organic resin while covering the oxide particles, forming a carbonaceous wall. Examples of non-oxidizing atmospheres include an argon atmosphere and a nitrogen atmosphere. Examples of reduced pressure atmospheres include an atmosphere with an absolute pressure of 133 Pa (1 Torr) or less. The heating temperature is preferably 500°C or higher and 1500°C or lower. The heating time can be determined appropriately depending on the materials used, the mixing ratio, and other heat treatment conditions, but is, for example, 0.5 hours to 3 hours, more preferably 1 hour to 3 hours.

[0038] <Removal of Oxide Particles> The oxide particles are removed by immersing the composite of the carbonaceous wall and the oxide particles obtained by the primary heat treatment in a removal solution that dissolves the oxide particles. Common inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and acetic acid, as well as hot water, can be used as the removal solution. When using an inorganic acid, it is preferable to use a dilute acid of 4 mol / L or less in order to prevent deterioration of the carbonaceous wall. When using hot water, it is preferable to use a temperature of 80°C or higher. The use of an inorganic acid as the removal solution has the advantage of quickly removing the oxide particles.

[0039] <Secondary Heat Treatment> The secondary heat treatment of the amorphous porous carbon obtained by removing the oxide particles is carried out by heating in a non-oxidizing atmosphere or a reduced-pressure atmosphere to a temperature above the temperature at which the amorphous carbon crystallizes. Examples of non-oxidizing atmospheres include an argon atmosphere or a nitrogen atmosphere. Examples of reduced-pressure atmospheres include an atmosphere with an absolute pressure of 133 Pa (1 Torr) or less. From the viewpoint of smoothly forming the desired crystal structure in a short time, the heating temperature is preferably 1650°C or higher, more preferably 1700°C or higher, and even more preferably 1750°C or higher. On the other hand, from the viewpoint of suppressing an extreme improvement in crystallinity, the heating temperature is preferably 2300°C or lower, and more preferably 2200°C or lower. The heat treatment time can be appropriately determined depending on the materials used, the mixing ratio, and other heat treatment conditions, but is, for example, 1 hour to 3 hours, more preferably 1 hour to 2 hours.

[0040] <<Porous Carbon Membrane>> A porous carbon membrane for a positive electrode of an air battery according to another aspect of the present invention (hereinafter, sometimes referred to as a "porous carbon membrane according to the second aspect") contains the porous carbon particles according to the first aspect described above, and has the following characteristics. Thereby, when used as a positive electrode of an air battery, an air battery having excellent cycle characteristics can be obtained, taking advantage of the characteristics of the carbon particles according to the first aspect.

[0041] A) Half-width of D-band peak in Raman spectrum The porous carbon film according to the second aspect has a half-width of D-band peak in Raman spectrum of 64 cm －１The half-width of the D band peak in the Raman spectrum is less than 64 cm －１ The half width of the D band peak in the Raman spectrum is preferably less than 63 cm, and the crystallinity of the carbon is not too low, so that the reaction between the electrolyte and oxygen, which tends to occur in a porous carbon membrane with a large amount of pores, and the resulting decomposition of the electrolyte can be suppressed, and the decrease in discharge capacity due to repeated charge and discharge can be suppressed. －１ It is preferable that:

[0042] In the porous carbon membrane according to the second aspect, the lower limit of the half-width of the D-band peak in the Raman spectrum is not particularly limited as long as it is obtained in the porous carbon membrane containing the porous carbon particles according to the first aspect. However, from the viewpoint of maintaining the affinity between the inner surfaces of the pores and the electrolyte and suppressing a decrease in discharge capacity due to repeated charge and discharge, it is preferable that the lower limit be 37 cm. －１ It is preferable that the length is 40 cm or more. －１ More preferably, it is equal to or greater than this.

[0043] B) Volume of pores with diameters of 1 nm or more and 1000 nm or less In the porous carbon membrane according to the second aspect, the volume of pores with diameters of 1 nm or more and 1000 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 1.2 cm ３ / g or more 8.0cm ３ / g or less. The volume of pores with diameters of 1 nm or more and 1000 nm or less in the porous carbon membrane is 1.2 cm ３ / g or more, it is possible to store more lithium peroxide, which is generated by the reaction of lithium ions with oxygen during discharge, and a lithium-air battery with a large discharge capacity can be obtained. From the viewpoint of obtaining a lithium-air battery with a large discharge capacity, the volume of the pores with a diameter of 1 nm or more and 1000 nm or less is set to 1.3 cm ３ / g or more, and ３ On the other hand, it is more preferable that the volume of pores with a diameter of 1 nm or more and 1000 nm or less is 8.0 cm ３ / g or less, the porous carbon membrane has sufficient strength. From the viewpoint of maintaining the strength of the porous carbon membrane, the volume of the pores having a diameter of 1 nm or more and 1000 nm or less is 6.0 cm３ / g or less is preferable.

[0044] C) Volume of pores with diameters of 1 nm or more and 100 nm or less In the porous carbon membrane according to the second aspect, the volume of pores with diameters of 1 nm or more and 100 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 0.8 cm ３ / g or more 7.0cm ３ As explained in the above f), the large volume of the pores with diameters of 1 nm to 100 nm reduces the size of the lithium peroxide produced during discharge of the lithium-air battery, facilitating the reaction during charging, and suppressing the decrease in discharge capacity due to repeated charge and discharge. This effect is achieved when the volume of the pores with diameters of 1 nm to 100 nm in the porous carbon membrane is 0.8 cm ３ / g or more, the volume of the pores with a diameter of 1 nm or more and 100 nm or less is set to 0.8 cm ３ In order to further suppress the decrease in discharge capacity due to repeated charge and discharge, the volume of pores with a diameter of 1 nm or more and 100 nm or less is set to 0.9 cm ３ / g or more, and ３ On the other hand, it is more preferable that the volume of pores with a diameter of 1 nm or more and 100 nm or less is 7.0 cm ３ / g or less, the porous carbon membrane has sufficient strength. From the viewpoint of maintaining the strength of the porous carbon membrane, the volume of the pores having a diameter of 1 nm or more and 100 nm or less is 5.0 cm ３ / g or less is preferable.

[0045] D) Specific Surface Area The porous carbon membrane according to the second aspect has a specific surface area of ​​400 cm2 or less, as determined by the BET method from an adsorption isotherm obtained by a nitrogen adsorption method. ２ / g or more 2000cm ２ / g or less. The specific surface area of ​​the porous carbon membrane determined by the BET method is 400 cm ２ / g or more, when used as the positive electrode of a lithium-air battery, there are more reaction sites for oxygen and lithium ions to receive electrons and become lithium peroxide during discharge, and more reaction sites for lithium peroxide to release electrons and become oxygen and lithium ions during charge, making it easier for the discharge reaction and the charge reaction to proceed. From the viewpoint of promoting the charge-discharge reaction, the specific surface area determined by the BET method is 500 cm ２ On the other hand, it is preferable that the specific surface area measured by the BET method is 2000 cm ２ / g or less, the porous carbon membrane has sufficient strength. From the viewpoint of maintaining the strength of the porous carbon membrane, the specific surface area determined by the BET method is 1800 cm ２ / g or less is preferable.

[0046] The porous carbon membrane according to the second aspect has the above-mentioned characteristics and, in addition, an apparent density of 0.10 g / cm ３ 0.20cm or more ３ / g or less. ３ When the apparent density is 0.11 g / cm or more, the strength of the porous carbon membrane becomes sufficient and breakage during assembly into an air battery is suppressed. ３ On the other hand, it is more preferable that the apparent density is 0.20 g / cm or more. ３ When the apparent density of the porous carbon membrane is 0.19 g / cm or less, the amount of voids in the porous carbon membrane is sufficient to ensure a migration path for oxygen used in the discharge reaction of the air battery, and an air battery with a large discharge capacity can be obtained. ３ More preferably, it is:

[0047] In addition to having the above-mentioned characteristics, the porous carbon membrane according to the second aspect preferably has a porosity of 85% or more and 99% or less. A porosity of 85% or more ensures sufficient void volume between the porous carbon particles constituting the porous carbon membrane. When used as a positive electrode of an air battery, oxygen necessary for the discharge reaction can smoothly move and diffuse within the porous carbon membrane, resulting in a large discharge capacity even under high load. From the viewpoint of maintaining the discharge capacity under high load, the porosity of the porous carbon membrane is more preferably 88% or more, and even more preferably 90% or more. On the other hand, a porosity of 99% or less ensures sufficient strength of the porous carbon membrane, thereby suppressing breakage during assembly into an air battery. From the viewpoint of maintaining the strength of the porous carbon membrane, the porosity of the porous carbon membrane is more preferably 97% or less, and even more preferably 95% or less. The porosity is calculated from the apparent density and true density of the porous carbon membrane by the formula: 1 - (apparent density of the porous carbon membrane) / (true density of the constituent material of the porous carbon membrane). As is clear from this formula, the voids between particles, which are expressed by the porosity, are different from the pores that the porous carbon particles themselves have, the volume of which is determined by the nitrogen adsorption method.

[0048] <Method for Producing Porous Carbon Membrane> An example of a method for producing a porous carbon membrane according to the second aspect will be described with reference to FIG.

[0049] <Preparation of Mixture Slurry (Step S1)> First, a mixture slurry is prepared. The mixture may, for example, contain 40% by mass or more and 90% by mass or less of porous carbon particles, 1% by mass or more and 15% by mass or less of carbon fibers, 5% by mass or more and 49% by mass or less of a polymeric binder material, and 10% by mass or less of carbon nanotubes as an optional component, as well as a solvent for uniformly dispersing them. Although carbon nanotubes are not an essential component, it is preferable to include them in order to obtain a reinforcing effect of the porous carbon membrane.

[0050] As the carbon fiber, for example, carbon fiber having a diameter of 0.1 μm or more and 20 μm or less and a length of 1 mm or more and 20 mm or less can be used.

[0051] Examples of polymeric materials that can be used as binders include polyacrylonitrile (PAN), polyvinylidene fluoride, polysulfone, polyethylene oxide (PEO), and solvent-soluble polyimide.

[0052] Examples of the solvent that can be used include dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), dimethylformamide (DMF), and dimethylacetamide (DMA).

[0053] The carbon nanotubes that can be used may have a diameter of 0.5 nm or more and 20 nm or less and a length of 1 μm or more and 20 μm or less, for example.

[0054] The above-mentioned composite materials are mixed before use. Mixing can be carried out by an appropriate method, such as manual mixing using a stirring rod or spatula, or mechanical mixing using a mixer. Examples of the mixer that can be used include a three-one motor-type agitator, homogenizer, planetary mixer, and the like.

[0055] <Molding (Step S2)> Next, the obtained mixture slurry is molded to obtain a molded body. The molding method is not particularly limited, but examples thereof include a well-known wet film-forming method using a doctor blade or the like. Other examples include a roll coater method, a die coater method, a spin coater method, and a spray coating method.

[0056] The shape of the molded body can vary depending on the purpose, for example, it can be a sheet of uniform thickness.

[0057] <Solvent Immersion (Step S3)> The molded body is then subjected to solvent immersion. Specifically, the molded body obtained in Step S2 is immersed in a solvent in which the binder polymer material contained therein has low solubility, to form a porous molded body. This solvent immersion step is a non-solvent-induced phase separation method in which the binder polymer material is precipitated between the porous carbon particles, thereby bonding the porous carbon particles together.

[0058] Examples of the solvent to be used include alcohols such as ethyl alcohol, methyl alcohol, isopropyl alcohol, and butyl alcohol, water, and mixed solvents thereof.

[0059] [Correction based on Rule 91, 12.11.2024] <Drying (Step S4)> Next, the porous molded body is dried to volatilize various solvents from the porous molded body. Drying methods include, for example, placing the porous molded body in a dry air environment, reduced pressure drying, and vacuum drying. In this drying step, the porous molded body may be heated to a temperature exceeding the boiling point of the solvent to accelerate the drying rate.

[0060] <Infusibilization (Step S5)> Next, the dried porous molded body is subjected to an infusibilization treatment. This treatment is performed for the purpose of preventing the polymeric binder material contained in the porous molded body from melting and separating during the carbonization treatment in the subsequent step, which would cause the shape of the molded body to collapse. Infusibilization can be achieved by oxidative crosslinking of the polymeric binder material to solidify it.

[0061] The infusibility is achieved by heating the porous molded body in the presence of oxygen using an oven furnace, an infrared irradiation furnace, or the like. The heating temperature is preferably 250°C or higher and 350°C or lower. By setting the heating temperature to 250°C or higher, sufficient oxidative crosslinking of the binder polymer material by air is achieved, and melting in the subsequent carbonization step can be suppressed. In order to further suppress melting of the binder polymer material, the heating temperature is more preferably 260°C or higher, and even more preferably 270°C or higher. On the other hand, by setting the heating temperature to 350°C or lower, decomposition of the binder polymer material can be suppressed. In order to further suppress decomposition of the binder polymer material, the heating temperature is more preferably 340°C or lower, and even more preferably 330°C or lower.

[0062] The rate of temperature rise to the heating temperature is preferably 100°C / min or less, more preferably 50°C / min or less, and even more preferably 30°C / min or less. By using the above rate of temperature rise, the polymer material for binder is sufficiently oxidized and crosslinked, and melting in the subsequent carbonization step can be suppressed. There is no particular lower limit to the rate of temperature rise, but from the viewpoint of shortening the heating time and reducing production costs, a rate of 0.01°C / min or more is preferred.

[0063] The infusibilization is preferably carried out under air circulation or air flow. Although infusibilization can be carried out in an atmosphere of a mixture of oxygen and an inert gas such as nitrogen or argon, the use of air is preferred from the viewpoint of cost. When air is flowed, in order to supply sufficient oxygen and promote infusibilization, the air flow rate is preferably 0.1 mL / min or more, more preferably 1 mL / min or more. On the other hand, in order to reduce production costs, the air flow rate is preferably 100 m ３ / min or less, and ３ / min or less is more preferable, and ３ It is more preferable to set it to 1 / min or less.

[0064] The holding time at the heating temperature during infusibility treatment is preferably 1 minute or more and 100 hours or less. By setting the holding time to 1 minute or more, the polymeric binder material can be sufficiently crosslinked, thereby suppressing melting during carbonization. In order to further suppress melting of the polymeric binder material, the holding time is preferably 10 minutes or more, and more preferably 20 minutes or more. On the other hand, by setting the holding time to 100 hours or less, the processing time can be shortened and manufacturing costs can be reduced. In order to further reduce manufacturing costs, the holding time is preferably 10 hours or less, and more preferably 5 hours or less.

[0065] Depending on the type of binder polymer material used, infusibility treatment can be omitted if not necessary. Binder polymer materials that require infusibility treatment are polymers with a structure that melts and liquefies when heated as is. To prevent this, intermolecular crosslinking must be promoted by oxygen, changing the structure to one that does not melt and liquefy when heated. Examples of binder polymer materials that require infusibility treatment include polyvinyl chloride (PVC) and polyvinyl acetate. On the other hand, binder polymer materials that do not require infusibility treatment are those that, even when heated as is, undergo intermolecular crosslinking due to their own functional groups, soften, but do not liquefy, and instead carbonize. Examples of binder polymer materials that do not require infusibility treatment include phenol formaldehyde resin (PF), polyvinylidene chloride (PVDC), polyphenylene (PP), cellulose, etc. Although polyacrylonitrile (PAN) is a polymer material that softens when heated as is and carbonization proceeds to a degree, when carbon fibers are industrially produced from polyacrylonitrile, in order to further promote the crosslinking reaction, the material is heated in air at 200°C to 400°C to be infusible, and carbonization is carried out after converting it into fibers that do not melt even at high temperatures. In the examples of the present invention described below, polyacrylonitrile (PAN) is used as the polymer material for the binder because of the ease of preparing a mixture slurry and the ease of non-solvent-induced phase separation, and infusibility is carried out in accordance with industrial carbon fiber production methods.

[0066] <Carbonization (Step S6)> Next, the porous molded body is subjected to a carbonization treatment. The purpose of carbonization is to convert the polymeric binder material into carbon, which imparts electrical conductivity and increases the binding strength of the porous carbon film with the porous carbon particles, carbon fibers, and carbon nanotubes.

[0067] The apparatus used for carbonization is not particularly limited, but for example, an oven furnace, a tubular furnace, a box furnace, an infrared irradiation furnace, a lead hammer furnace, or the like can be used.

[0068] The atmosphere during carbonization was argon (Ar) gas, nitrogen (N ２An inert atmosphere such as a gas containing 100 mL of HCl or 100 mL of HCl is preferred. The inert atmosphere may be formed by sealing the gas in the processing device, or may be formed while circulating the gas through the processing device. When circulating the gas (inert gas), the flow rate is not particularly limited, but from the viewpoint of reducing the influence of other gases such as outside air, it is preferably 0.1 mL / min or more, more preferably 1 mL / min or more, and even more preferably 10 mL / min or more. On the other hand, from the viewpoint of reducing manufacturing costs, the flow rate of the inert gas is preferably 100 mL / min or more. ３ / min or less, and ３ / min or less is more preferable, and ３ It is more preferable to set it to 1 / min or less.

[0069] From the viewpoint of sufficiently carbonizing the polymer material for binder, the temperature during carbonization is preferably 600° C. or higher, more preferably 700° C. or higher, and even more preferably 800° C. or higher. On the other hand, from the viewpoint of suppressing an extreme increase in the crystallinity of the porous carbon particles and the carbon produced by carbonization, the carbonization temperature is preferably 1700° C. or lower, more preferably 1600° C. or lower, and even more preferably 1500° C. or lower.

[0070] The temperature rise rate during carbonization is preferably 100° C. / min or less, more preferably 50° C. / min or less, and even more preferably 30° C. / min or less, from the viewpoint of sufficiently carbonizing the binder polymer. There is no particular restriction on the lower limit of the temperature rise rate, but from the viewpoint of shortening the heating time and reducing the production cost, 0.01° C. / min or more is preferred.

[0071] <Air Battery> An air battery according to yet another aspect of the present invention (hereinafter sometimes referred to as "air battery according to the third aspect") includes the porous carbon membrane according to the second aspect described above in the positive electrode. This results in a lithium-air battery that combines a large discharge capacity with excellent cycle characteristics. Hereinafter, an example of the structure of the air battery according to the third aspect will be described with reference to the drawings.

[0072] <Coin Cell> Fig. 2 is a cross-sectional schematic diagram showing the structure of a coin cell, which is one embodiment of the air battery according to the third aspect. The coin cell 600 includes a laminate in which an anode structure 610 and a cathode structure 620 are stacked with a separator 660 interposed therebetween. This laminate is restrained by a coin cell-type restraining device 630 to maintain the laminated structure. Note that an insulating gasket 685 is disposed between the coin cell-type restraining device 630 and the cathode structure 620, ensuring insulation between the coin cell-type restraining device 630 and the cathode structure 620.

[0073] The negative electrode structure 610 is composed of a current collector 635, a metal layer 640 arranged on the current collector 635, and columnar spacers 650 arranged on both ends of the metal layer 640. A space 670 is provided between the metal layer 640 and the separator 660, and is filled with an electrolyte solution described below.

[0074] For example, metals such as copper (Cu), tungsten (W), aluminum (Al), nickel (Ni), titanium (Ti), gold (Au), silver (Ag), platinum (Pt), and palladium (Pd), as well as alloys containing any of these metals and compounds containing any of these metals (e.g., compounds with carbon and / or nitrogen) can be used as the current collector 635. In the case of alloys, iron (Fe) and chromium (Cr) can also be included.

[0075] The metal layer 640 contains an alkali metal and / or an alkaline earth metal, and is preferably a layer made of lithium metal.

[0076] The spacer 650 is an insulator. The material may be a metal oxide, a metal nitride, a metal oxynitride, or the like. For example, Al ２ O ３ , Ta ２ O ５ , TiO ２ , ZnO, ZrO ２ , SiO ２ , B ２ O ３ , P ２ O ５ , GeO ２ , Li ２ O, Na ２ O.K.２ O, MgO, CaO, SrO, BaO, Si ３ N ４ , AlN, and AlO ｘ N １－ｘ (0<x<1), etc. ２ O ３ and SiO ２ is preferred in that it is easily available and has excellent processability.

[0077] The spacer 650 may be made of a resin. Examples of the resin include polyolefin resin, polyester resin, polyimide resin, and polyether ether ketone (PEEK) resin. Examples of the polyolefin resin include polyethylene and polypropylene. Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polytributylene terephthalate (PTT). These resins are preferred because they are easily available and have excellent processability.

[0078] The positive electrode structure 620 includes a porous carbon film electrode 690 in mechanical and electrical contact with a metal-containing mesh (metal mesh) 680, which serves as a current collector. In this case, the metal mesh 680 serves as a positive electrode substrate and also functions as a flow path for air or oxygen to pass through.

[0079] The metal mesh 680 can be made of any of the materials listed above as examples of materials that can be used for the current collector 635 that constitutes the negative electrode structure 610. The mesh can have a thickness of 0.2 mm and a mesh size of 1 mm, for example.

[0080] The porous carbon membrane electrode 690 uses the porous carbon membrane according to the second aspect.

[0081] In the coin cell 600 shown in FIG. 2 , the positive electrode structure 620 has a porous carbon film electrode 690 and a metal mesh 680, but the air battery according to the third aspect is not limited to this structure, and the positive electrode structure 620 may have only the porous carbon film electrode 690.

[0082] A separator 660 is disposed between the negative electrode structure 610 and the positive electrode structure 620. The separator 660 is a porous insulator that allows alkali metal ions and / or alkaline earth metal ions to pass through.

[0083] The separator 660 is composed of the metal layer 640, any inorganic material (including a metal material) that is not reactive with the electrolyte, and an organic material. Examples of materials that make up the separator 660 include resins such as polyethylene, polypropylene, and polyolefin, as well as glass. The separator 660 may be a woven or nonwoven fabric made of fibers of the above materials.

[0084] The space 670 between the metal layer 640 and the separator 660, and the voids in the separator 660, are filled with an electrolyte.

[0085] The electrolyte may be any aqueous or non-aqueous solution containing an alkali metal salt and / or an alkaline earth metal salt. Examples of lithium salts used in aqueous electrolytes include LiOH, LiCl, and LiNO. ３ , and Li ２ SO ４ In this case, the solvent may be water or a water-soluble solvent.

[0086] Examples of lithium salts used in non-aqueous electrolytes include LiPF ６ , LiBF ４ , LiSbF ６ , LiSiF ６ , LiAsF ６ , LiN(SO ２ C ２ F ５ ) ２ , Li(FSO ２ ) ２ N, LiCF ３ SO ３ (LiTfO), Li(CF ３ SO ２ ) ２ N (LiTFSI), LiC ４ F ９ SO ３ , LiClO ４, LiAlO ２ , LiAlCl ４ , and LiB(C ２ O ４ ) ２ etc.

[0087] Examples of non-aqueous solvents used in the non-aqueous electrolyte include glymes (monoglyme, diglyme, triglyme, and tetraglyme), methyl butyl ether, diethyl ether, ethyl butyl ether, dibutyl ether, polyethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, cyclohexanone, dioxane, dimethoxyethane, 2-methyltetrahydrofuran, 2,2-dimethyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, methyl formate, ethyl formate, dimethyl carbonate, and diethyl carbonate. ester, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, polyethylene carbonate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, acetonitrile, benzonitrile, nitromethane, nitrobenzene, triethylamine, triphenylamine, tetraethylene glycol diamine, dimethylformamide, diethylformamide, N-methylpyrrolidone, dimethyl sulfone, tetramethylene sulfone, triethylphosphine oxide, 1,3-dioxolane, and sulfolane.

[0088] The coin cell 600 is manufactured, for example, by the following procedure. First, a negative electrode structure 610 is prepared. The negative electrode structure 610 is obtained by stacking a disk-shaped metal layer 640 made of lithium or the like on a disk-shaped current collector 635, the metal layer 640 being concentric with the current collector 635 and having a smaller diameter than the current collector 635, and pressing a columnar spacer 650 onto the current collector 635.

[0089] Next, a separator 660 is prepared and pressed onto the spacer 650. At this time, a space 670 is formed between the metal layer 640 (lithium metal), the spacer 650, and the separator 660.

[0090] Thereafter, the separator 660 is filled with the electrolyte solution. At this time, the space 670 is also filled with the electrolyte solution.

[0091] Thereafter, a metal mesh 680 is placed on the porous carbon film electrode 690 to prepare a positive electrode structure 620 .

[0092] Thereafter, the positive electrode structure 620 is attached to a separator 660 filled with an electrolyte solution, and the assembly is restrained by a coin cell-type restraining device 630 to form a coin cell 600. Each of the above steps is preferably performed in dry air, for example, in dry air with a dew point temperature of −50° C. or lower.

[0093] 3 is a cross-sectional schematic diagram showing the structure of a stacked-type air battery, which is one embodiment of the air battery according to the third aspect. The stacked-type air battery 500 has a stacked structure in which a positive electrode structure 510 and a negative electrode structure 100 are stacked via a separator 540. The number of stacked pairs may be one or more pairs, with one pair consisting of one positive electrode structure 510 and one negative electrode structure 100, and there is no particular upper limit to the number of pairs.

[0094] [Correction based on Rule 91, 12.11.2024] The negative electrode structure 100 is composed of a pair of negative electrode active material layers (metal layers) and a negative electrode current collector 520 sandwiched between them. The negative electrode active material layers can be made of the same material as the metal layer 640 in the coin cell 600 described above. The negative electrode current collector 520 can be made of the same material as the current collector 635 in the coin cell 600 described above.

[0095] [Correction based on Rule 91, 12.11.2024] The positive electrode structure 510 is composed of a pair of laminates each consisting of a porous carbon membrane electrode 550 and a gas diffusion layer 560, and a positive electrode current collector 525 sandwiched between the laminates. The gas diffusion layer 560 and the porous carbon membrane electrode 550 are arranged in this order from the positive electrode current collector 525 side.

[0096] The porous carbon membrane electrode 550 uses the porous carbon membrane according to the second aspect.

[0097] [Correction based on Rule 91, 12 / 11 / 2024] The gas diffusion layer 560 is configured to allow air, oxygen, and other gases to pass between the porous carbon membrane electrode 550 and the outside of the battery. The gas diffusion layer 560 also functions as a path for electrons to travel between the porous carbon membrane electrode 550 and the positive electrode current collector 525. Therefore, the gas diffusion layer 560 must be breathable and electronically conductive. Examples of materials that can be used for the gas diffusion layer 560 include Toray's carbon paper TGP-H and Kureha's KUREKA E704.

[0098] [Correction based on Rule 91 12.11.2024] The positive electrode current collector 525 also functions as a flow path for air or oxygen, so that the stacked-type air battery 500 can have a larger capacity with a simpler structure.

[0099] [Correction based on Rule 91, 12 / 11 / 2024] Metals such as copper (Cu), tungsten (W), aluminum (Al), nickel (Ni), titanium (Ti), gold (Au), silver (Ag), platinum (Pt), and palladium (Pd), as well as alloys containing any of these metals and compounds containing any of these metals (e.g., compounds with carbon and / or nitrogen), can be used for the negative electrode current collector 520 and the positive electrode current collector 525. When an alloy is used, it may also contain iron (Fe) and chromium (Cr).

[0100] [Correction based on Rule 91, 12.11.2024] The stacked-type air battery 500 is manufactured, for example, by the following procedure: First, the negative electrode structure 100 is constructed from a pair of negative electrode active material layers (metal layers) and a negative electrode current collector 520 sandwiched between them, and the negative electrode current collector 520 is surrounded by a separator 540 so that it extends to the outside, and the space within the separator is filled with an electrolyte.

[0101] Next, the positive electrode structure 510 is constructed from a pair of laminates each consisting of a porous carbon membrane electrode 550 and a gas diffusion layer 560, and a positive electrode current collector 525 sandwiched therebetween. The gas diffusion layer 560 and the porous carbon membrane 550 are arranged in this order from the positive electrode current collector 525 side.

[0102] Next, the negative electrode structure 100 and the positive electrode structure 510 are stacked with a separator 540 interposed therebetween to form a stacked air battery 500. This stacked air battery 500 may be housed in a storage container (not shown).

[0103] As the air battery according to the third aspect is named "air battery" because oxygen in the air serves as the positive electrode active material, it operates satisfactorily when supplied with oxygen at a concentration of 21% or more, which is the oxygen concentration in air. However, in order to reduce the influence of diffusion limitation, it is preferable to supply oxygen at a higher concentration, and the best performance can be achieved if pure oxygen can be supplied.

[0104] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0105] The physical properties of the porous carbon particles and porous carbon membranes produced in the following Examples and Comparative Examples were measured by the following methods.

[0106] [Correction based on Rule 91, 12.11.2024] (1) Half-Width of the D-Band Peak in the Raman Spectrum: Raman spectra were measured using a Touch-VIS-NIR Raman spectrometer (manufactured by Nanophoton Inc.) with a 10x objective lens, an excitation wavelength of 532 nm, and an irradiation laser power of 1 mW. The peak width of the D-band peak derived from turbostratic carbon in the obtained Raman spectrum was measured at the position where the intensity was half of its maximum value. This was repeated three times, and the average value of the peak widths obtained in each measurement was taken as the half-width of the D-band peak. An illustration of this half-width measurement method is shown in Figure 4.

[0107] [Correction based on Rule 91, 12 / 11 / 2024] (2) Half-width of the G-band peak in the Raman spectrum: Raman spectra were measured using a Touch-VIS-NIR Raman spectrometer (manufactured by Nanophoton Inc.) with a 10x objective lens, an excitation wavelength of 532 nm, and an irradiation laser power of 1 mW. The peak width of the G-band peak derived from crystalline carbon in the obtained Raman spectrum was measured at the position where the intensity was half of its maximum value. This was repeated three times, and the average of the peak widths obtained in each measurement was taken as the half-width of the G-band peak.

[0108] [Correction based on Rule 91 12.11.2024] (3) R value in Raman spectrum Raman spectrum was measured using a Raman spectrometer Touch-VIS-NIR (manufactured by Nanophoton Co., Ltd.) with a 10x objective lens, an excitation wavelength of 532 nm, and an irradiation laser power of 1 mW. The peak intensity (height) of the G band derived from crystalline carbon in the obtained Raman spectrum was calculated as I Ｇ , the peak intensity (height) of the D band derived from turbostratic carbon is I Ｄ As a result, the ratio of the two, I Ｄ / I Ｇ This was repeated three times, and the I obtained in each measurement was calculated. Ｄ / I Ｇ The average value was taken as the R value.

[0109] (4) Peak Position of 002 Reflection in X-ray Diffraction Using an X-ray diffractometer RINT-TTR3 (manufactured by Rigaku Corporation), the radiation source was CuKα, the acceleration voltage was 50 kV, the current was 300 mA, the divergence slit width was 1 / 2 deg, the receiving slit width was open, and the scattering slit width was 1 / 2 deg. The measurement range was 5 deg≦2θ≦90 deg, and the measurement step interval was 0.02 deg, to obtain an X-ray diffraction (XRD) pattern. The obtained XRD pattern was subjected to peak separation using the Pearson VII function, and the 2θ value showing the maximum diffraction intensity of each peak indexed to 002 was determined as the peak position of the 002 reflection.

[0110] (5) Interplanar spacing d of (002) plane ００２ From the peak positions of the 002 reflection obtained in (4) above, the interplanar spacing d of the (002) plane is calculated using the Bragg equation.００２ was calculated.

[0111] (6) Volume of pores with diameters of 1 nm to 1000 nm An adsorption isotherm was obtained by a nitrogen adsorption method using a 3Flex (manufactured by Micromeritics Instrument Corp.) From the obtained adsorption isotherm, the volume of pores with diameters of 1 nm to 1000 nm was calculated using the BJH (Barrett-Joyner-Hallenda) method.

[0112] (7) Volume of pores with diameters of 1 nm to 100 nm An adsorption isotherm was obtained by a nitrogen adsorption method using a 3Flex (manufactured by Micromeritics Instrument Corp.) From the obtained adsorption isotherm, the volume of pores with diameters of 1 nm to 100 nm was calculated using the BJH method.

[0113] (8) Average pore diameter of pores with a diameter of 1 nm or more and 1000 nm or less An adsorption isotherm was obtained by a nitrogen adsorption method using a 3Flex (manufactured by Micromeritics Instrument Corp.) From the obtained adsorption isotherm, the average pore diameter of pores with a diameter of 1 nm or more and 1000 nm or less was calculated using the BJH method.

[0114] [Correction based on Rule 91 12.11.2024] (9) Volume of pores with diameters of 20 nm to 1000 nm: An adsorption isotherm was obtained by the nitrogen adsorption method using a 3Flex (Micromeritics Instrument Corp.). From the obtained adsorption isotherm, the volume of pores with diameters of 20 nm to 1000 nm was calculated using the BJH (Barrett-Joyner-Hallenda) method.

[0115] (10) Percentage of the volume of pores with a diameter of 1 nm or more and 100 nm or less in the volume of pores with a diameter of 1 nm or more and 1000 nm or less This was calculated using the volume of pores with a diameter of 1 nm or more and 1000 nm or less obtained in (6) above and the volume of pores with a diameter of 1 nm or more and 100 nm or less obtained in (7) above using the following formula: {(Volume of pores with a diameter of 1 nm or more and 100 nm or less) / (Volume of pores with a diameter of 1 nm or more and 1000 nm or less)}×100

[0116] (11) Percentage of the volume of pores with a diameter of 20 nm or more and 1000 nm or less in the volume of pores with a diameter of 1 nm or more and 1000 nm or less This was calculated using the volume of pores with a diameter of 1 nm or more and 1000 nm or less obtained in (6) above and the volume of pores with a diameter of 20 nm or more and 1000 nm or less obtained in (9) above using the following formula: {(Volume of pores with a diameter of 20 nm or more and 1000 nm or less) / (Volume of pores with a diameter of 1 nm or more and 1000 nm or less)}×100

[0117] (12) BET Specific Surface Area An adsorption isotherm was obtained by a nitrogen adsorption method using a 3Flex (manufactured by Micromeritics Instrument Corp.) The specific surface area was calculated from the obtained adsorption isotherm using the BET (Brunauer-Emmett-Teller) method.

[0118] (13) Median diameter d50: Measured using a laser diffraction particle size distribution analyzer LA-950 (manufactured by Horiba, Ltd.) Pure water was used as the solvent, and PEO (polyethylene oxide) or a PEO equivalent was used as the dispersant.

[0119] (14) Apparent Density: Calculated by dividing the mass of the porous carbon membrane by its volume.

[0120] (15) Porosity (%) Calculated from the apparent density obtained in (14) above and the true density of the material constituting the porous carbon membrane using the following formula: {1 - (apparent density of porous carbon membrane) / (true density of material constituting the porous carbon membrane)} x 100

[0121] Example 1 Production of Porous Carbon Particles A mixture of organic phenolic resin and oxide particles of MgO (average crystallite diameter 10 nm) in a mass ratio of 25:75 was prepared and heat-treated in a nitrogen gas atmosphere at 900°C for 1 hour (first heat treatment) to carbonize the phenolic resin and obtain a composite of carbonaceous walls and MgO particles. The composite was then washed with a 1 mol / L sulfuric acid solution to completely elute the MgO, obtaining amorphous porous carbon having numerous mesopores and micropores. This amorphous porous carbon was then heat-treated in a nitrogen gas atmosphere at 1800°C for 1 hour (second heat treatment) to crystallize the carbon, thereby obtaining porous carbon particles PC-1 according to Example 1.

[0122] The physical properties of the porous carbon particles PC-1 according to Example 1 were measured by the above methods. The half-width of the D band peak in the Raman spectrum was 44 cm. －１ It was confirmed that the porous carbon particles had an appropriate amount of crystal disorder within the scope of the present invention. X-ray diffraction measurement of PC-1 yielded the chart shown in FIG. 5, in which three peaks indexed to 002 were observed at 2θ=23.83 deg, 2θ=25.83 deg, and 2θ=26.50 deg, respectively. The interplanar spacing d of the (002) plane calculated from each peak was ００２ The peaks with the same index appear when the carbonization temperature (heat treatment temperature) of the phenolic resin increases, indicating the coexistence of carbons with different crystallinity. The volume of pores with diameters of 1 nm to 1000 nm in PC-1 was 2.01 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 6 nm, and the BET specific surface area is 1423 m ２ The physical properties of the porous carbon particles PC-1 according to Example 1 are summarized in Tables 1 and 2. The results of Raman spectrum measurement of these porous carbon particles are shown in FIG.

[0123] <<Preparation of porous carbon membrane>> <Step of preparing mixture slurry> As the porous carbon particles, 75 parts by mass of the porous carbon particles PC-1 according to Example 1, 5 parts by mass of carbon fibers (average fiber diameter 6 μm, average length 3 mm), 5 parts by mass of carbon nanotubes (diameter 2 nm, length 5 μm or less), and 15 parts by mass of polyacrylonitrile (PAN) as a polymeric binder material were prepared, and N-methylpyrrolidone was added to these as a solvent, followed by mixing in a rotary and revolving kneader ARE310 (manufactured by Thinky Co., Ltd.) to prepare a mixture slurry.

[0124] <Molding Step> The obtained mixture slurry was molded into a sheet having a thickness of 400 μm by a wet film-forming method using a doctor blade.

[0125] <Solvent Immersion Step> The obtained sheet was immersed in methanol, a poor solvent for polyacrylonitrile (PAN), to form a porous membrane by non-solvent-induced phase separation. Non-solvent-induced phase separation is a method of immersing a polymer solution in a non-solvent to cause phase separation and precipitation of the polymer. In this example, the sheet, in which porous carbon particles, carbon fibers, and carbon nanotubes are dispersed in a solution of polyacrylonitrile (PAN), a binder polymer material, dissolved in N-methylpyrrolidone, is immersed in methanol, a non-solvent (poor solvent), to cause phase separation and precipitation of the polyacrylonitrile (PAN) in a state where the porous carbon particles, carbon fibers, and carbon nanotubes are bonded together, forming a carbonaceous membrane with the porous carbon particles as its skeleton. At this time, most of the N-methylpyrrolidone dissolves in the methanol. Specifically, the obtained sheet was placed in a tray, 220 g of methanol was added thereto, and the sheet was left to stand for 2 hours. After that, the methanol in the tray was discharged, and 220 g of fresh methanol was added thereto and the sheet was left to stand for 17 hours. After that, the methanol in the tray was discharged.

[0126] <Drying Step> After immersion in methanol, the porous membrane was taken out from the tray and dried at 50°C for 2 hours and then at 80°C for 10 hours in order to remove the volatile solvent contained in the porous membrane.

[0127] <Infusible Process> The dried porous membrane was subjected to an infusible heat treatment at 320°C for 3 hours in an air circulating atmosphere using an inert oven DN411 (manufactured by Yamato Scientific Co., Ltd.), and the polyacrylonitrile (PAN) in the dried porous membrane was oxidized and cyclized through cross-linking, converting it into an infusible resin.

[0128] <Carbonization Step> The stabilized porous membrane having a length of 90 mm and a width of 80 mm obtained by the stabilization treatment was heated to 1,050°C at a heating rate of 10°C / min in a box furnace (manufactured by Denken Hydental Co., Ltd.) while flowing nitrogen gas at 600 mL / min, and then held at 1,050°C for 3 hours, followed by cooling to room temperature, thereby carbonizing the stabilized PAN and obtaining a porous carbon membrane according to Example 1 made entirely of carbon. The conditions for each of the above steps are summarized in Table 3.

[0129] The obtained porous carbon film had a D band peak half width of 43 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with an appropriately low crystallinity, but the crystallinity as a whole was not too low. Furthermore, the volume of pores with a diameter of 1 nm or more and 1000 nm or less measured by the BJH method was 1.59 cm ３ / g, BET specific surface area is 1169 m ２ The physical properties of the porous carbon membrane according to Example 1 are shown in Table 4.

[0130] <<Preparation of Air Battery and Measurement of Discharge Capacity>> A CR2032-type coin cell 800 having the structure shown in FIG. 7 was prepared using the porous carbon membrane according to Example 1 as the positive electrode, and the discharge capacity was measured. A piece cut to a diameter of 16 mm from the porous carbon membrane according to Example 1 was prepared as the positive electrode 840. GDL-TGP-H030 (manufactured by Toray Industries, Inc., diameter 16 mm, thickness 0.1 mm) was prepared as the gas diffusion layer 830 of the positive electrode. Metallic lithium (diameter 16 mm, thickness 0.2 mm) was prepared as the negative electrode 860. Glass fiber paper (Whatman (registered trademark), GF / A) containing 100 μL of a 1 M tetraethylene glycol dimethyl ether solution of LiTFS (lithium trifluoromethanesulfonate), which served as the electrolyte, was prepared as the separator 850. Additionally, a stainless steel metal mesh 820, a stainless steel spacer 870, a disc spring 875, a positive electrode can 810, a negative electrode can 815, and a gasket 880 were prepared. The above materials were assembled in a dry room with a dry air atmosphere at a dew point temperature of −50°C or lower to produce a coin cell according to Example 1. In the coin cell, the gasket 880 is sandwiched between the positive electrode can 810 and the negative electrode can 815, and serves to prevent misalignment between them and ensure insulation between them. Outside air (oxygen in this evaluation) is taken into the positive electrode 840 through the metal mesh 820 and the gas diffusion layer 830.

[0131] [Correction based on Rule 91 12.11.2024] The discharge capacity of the coin cell was measured and calculated by the following method: The coin cell according to Example 1 was charged in a pure oxygen atmosphere at a current density of 0.4 mA / cm ２ The battery was discharged at 1000 kJ / s, and the discharge capacity was measured when the voltage dropped to 2.3 V, which was defined as the discharge end point. The discharge capacity per positive electrode area was calculated by dividing the obtained discharge capacity by the area of ​​the porous carbon membrane used as the positive electrode. The discharge capacity per positive electrode mass (specific capacity) was also calculated by dividing the obtained discharge capacity by the mass of the porous carbon membrane used as the positive electrode. As a result, the discharge capacity per positive electrode area was 8.0 mAh / cm ２ The discharge capacity per mass of the positive electrode was 1245 mAh / g. These results are shown in Table 5 together with the basis weight of the positive electrode.

[0132] <<Cycle Characteristics of Air Battery>> A cell 200 for evaluating cycle characteristics was fabricated using the porous carbon membrane according to Example 1 as the positive electrode, as shown in FIG. 8 , and the cycle characteristics were evaluated. The porous carbon membrane according to Example 1 was cut into a 20 mm square and prepared as the positive electrode 101. Metallic lithium (20 mm square, 0.1 mm thick) was prepared as the negative electrode 105. Two TR-7 separators (manufactured by Toray Industries, Inc., 22 mm square) were prepared as the separator 109. GDL-TGP-H030 (manufactured by Toray Industries, Inc., 0.1 mm thick, 20 mm square) was prepared as the gas diffusion layer 102 of the positive electrode. LICG-AG01 (manufactured by Ohara Inc., 23 mm square) was prepared as the solid electrolyte membrane 108. A stainless steel foil (20 μm thick, 20 mm×60 mm square) was prepared as the positive electrode current collector 103, and a copper foil (5 μm thick, 20 mm×60 mm square) was prepared as the negative electrode current collector 106. A nonaqueous electrolyte solution was prepared using 0.5 M LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), 0.5 M LiNO ３ , and tetraethylene glycol dimethyl ether in which 0.2 M LiBr was dissolved were prepared. After the above nonaqueous electrolyte solution was impregnated into the separator 109, the negative electrode current collector 106, the negative electrode 105, the separator 109, the solid electrolyte membrane 108, the separator 109, the positive electrode 101, the gas diffusion layer 102, and the positive electrode current collector 103 were stacked in this order, and the top and bottom surfaces were sandwiched between stainless steel plates 111 via glass plates 110, and further secured with fixing screws 112 to form the cycle performance evaluation cell 200 according to Example 1. The cell was assembled in a dry room with a dry air atmosphere having a dew point temperature of −50°C or lower. In the cycle performance evaluation cell 200, outside air (oxygen in this case) was taken into the positive electrode 101 through the gas diffusion layer 102, and the generated gas was discharged through the gas diffusion layer 102.

[0133] The cycle characteristics were evaluated by first placing the cycle characteristic evaluation cell 200 in a pure oxygen atmosphere and then charging at a current density of 0.4 mA / cm ２ After 0.5 hours of rest, the current density was 0.4 mA / cm ２The conditioning operation was performed by repeating this cycle three times. This conditioning operation is not included in the number of cycles. After that, the cycle characteristics were evaluated by charging the battery at a current density of 0.4 mA / cm for one hour and then resting for 0.5 hours. ２ After 0.5 hours of rest, the current density was 0.4 mA / cm ２ This cycle was repeated, with the discharge limit voltage being 2.0 V and the charge limit voltage being 4.8 V. ２ Since the discharge is performed for 10 hours at 4mAh / cm ２ The discharge capacity is 4 mAh / cm ２ When the capacity drops to 80% or less, that is, 3.2 mAh / cm ２ The evaluation was terminated when the discharge capacity was 3.2 mAh / cm ２ The number of cycles up to just before the temperature reached or below this value was defined as the cycle number. As a result, the number of cycles was a large value of 38. Table 5 shows the electrode basis weight, the amount of electrolyte used in preparing the evaluation cell, and the number of cycles.

[0134] Comparative Example 1 <<Preparation of Porous Carbon Particles>> Porous carbon particles CPC-1 according to Comparative Example 1 were prepared in the same manner as in Example 1, except that the secondary heat treatment was not carried out.

[0135] The porous carbon particles CPC-1 according to Comparative Example 1 have a D band peak half width of 189 cm in the Raman spectrum. －１ It was found that the crystal disorder was too large. As a result of X-ray diffraction measurement of CPC-1, the chart shown in FIG. 9 was obtained, and one peak indexed to 002 was confirmed at 2θ=23.15 deg. The interplanar spacing d of the (002) plane calculated from this peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in CPC-1 was 2.48 cm ３ / g, the average pore size of pores with diameters of 1 nm to 1000 nm is 5 nm, and the BET specific surface area is 1898 m ２The physical properties of the porous carbon particles CPC-1 according to Comparative Example 1 are summarized in Tables 1 and 2. The Raman spectrum of the porous carbon particles CPC-1 is shown in FIG.

[0136] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 1 was prepared in the same manner as in Example 1, except that porous carbon particles CPC-1 according to Comparative Example 1 were used as the porous carbon particles and the sheet thickness in the molding step was set to 300 μm. The preparation conditions for the porous carbon membrane according to Comparative Example 1 are summarized in Table 3.

[0137] The obtained porous carbon film had a D band peak half width of 86 cm in the Raman spectrum. －１ It was found that the porous carbon membrane had excessive crystal disorder. The volume of the pores with diameters of 1 nm to 1000 nm was 1.77 cm ３ / g, BET specific surface area is 1449 m ２ The physical properties of the porous carbon membrane according to Comparative Example 1 are shown in Table 4.

[0138] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 1 were produced in the same manner as in Example 1, except that the porous carbon film according to Comparative Example 1 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0139] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 8.0 mAh / cm ２ Although the discharge capacity per mass of the positive electrode was a large value of 1544 mAh / g, the number of cycles was only 16. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0140] [Example 2] <<Preparation of porous carbon particles>> Porous carbon particles PC-2 according to Example 2 were prepared in the same manner as in Example 1, except that the mixing ratio of the phenolic resin to MgO was 35:65 by mass.

[0141] The porous carbon particles PC-2 according to Example 2 have a D band peak half width of 50 cm in the Raman spectrum. －１It was confirmed that the porous carbon particles had an appropriate amount of crystal disorder within the scope of the present invention. As a result of X-ray diffraction measurement of PC-2, the chart shown in FIG. 11 was obtained, and three peaks indexed to 002 were confirmed at 2θ=24.41 deg, 2θ=26.12 deg, and 2θ=26.45 deg, respectively. The interplanar spacing d of the (002) plane calculated from each peak was ００２ The pore diameters of PC-2 were 0.3644 nm, 0.3409 nm, and 0.3367 nm, respectively. The volume of pores with diameters of 1 nm to 1000 nm in PC-2 was 2.54 cm ３ / g, the average pore diameter of pores with a diameter of 1 nm to 1000 nm is 8 nm, and the BET specific surface area is 1280 m ２ The physical properties of the porous carbon particles PC-2 according to Example 2 are shown in Tables 1 and 2.

[0142] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Example 2 was prepared in the same manner as in Example 1, except that the porous carbon particles PC-2 according to Example 2 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Example 2 are summarized in Table 3.

[0143] The obtained porous carbon film had a D band peak half width of 46 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with a moderately low crystallinity, but the crystallinity as a whole was not too low. In addition, the volume of pores with a diameter of 1 nm or more and 1000 nm or less was 2.38 cm ３ / g, BET specific surface area is 1051 m ２ The physical properties of the porous carbon membrane according to Example 2 are shown in Table 4.

[0144] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Example 2 were produced in the same manner as in Example 1, except that the porous carbon film according to Example 2 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0145] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 15.1 mAh / cm ２The discharge capacity per mass of the positive electrode was a large value of 2187 mAh / g, and the number of cycles was also high at 39. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0146] Comparative Example 2 <<Preparation of Porous Carbon Particles>> Porous carbon particles CPC-2 according to Comparative Example 2 were prepared in the same manner as in Example 2, except that the secondary heat treatment was not carried out.

[0147] The porous carbon particles CPC-2 according to Comparative Example 2 have a D band peak half width of 181 cm in the Raman spectrum. －１ It was found that the crystal disorder was too large. As a result of X-ray diffraction measurement of CPC-2, the chart shown in FIG. 12 was obtained, and one peak indexed to 002 was confirmed at 2θ=23.59 deg. The interplanar spacing d of the (002) plane calculated from this peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in CPC-2 was 3.46 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 9 nm, and the BET specific surface area is 1615 m ２ The physical properties of the porous carbon particles CPC-2 according to Comparative Example 2 are shown in Tables 1 and 2.

[0148] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 2 was prepared in the same manner as in Example 1, except that porous carbon particles CPC-2 according to Comparative Example 2 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Comparative Example 2 are summarized in Table 3.

[0149] The obtained porous carbon film had a D band peak half width of 71 cm in the Raman spectrum. －１ It was found that the porous carbon membrane had excessive crystal disorder. The volume of the pores with diameters of 1 nm to 1000 nm was 2.76 cm ３ / g, BET specific surface area is 1299 m ２ The physical properties of the porous carbon membrane according to Comparative Example 2 are shown in Table 4.

[0150] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 2 were produced in the same manner as in Example 1, except that the porous carbon film according to Comparative Example 2 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0151] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 9.8 mAh / cm ２ Although the discharge capacity per mass of the positive electrode was a large value of 2086 mAh / g, the number of cycles was only 19. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0152] Example 3 <<Preparation of Porous Carbon Particles>> Porous carbon particles PC-3 according to Example 3 were prepared in the same manner as in Example 1, except that MgO having an average crystallite diameter of 20 nm was used and the mixing ratio of the phenol resin to MgO was set to 30:70 by mass.

[0153] The porous carbon particles PC-3 according to Example 3 have a D band peak half width of 46 cm in the Raman spectrum. －１ It was confirmed that the porous carbon particles had an appropriate amount of crystal disorder within the scope of the present invention. As a result of X-ray diffraction measurement of PC-3, the chart shown in FIG. 13 was obtained, and three peaks indexed to 002 were confirmed at 2θ=24.32 deg, 2θ=25.88 deg, and 2θ=26.42 deg, respectively. The interplanar spacing d of the (002) plane calculated from each peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in PC-3 was 3.76 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 17 nm, and the BET specific surface area is 877 m ２ The physical properties of the porous carbon particles PC-3 according to Example 3 are shown in Tables 1 and 2.

[0154] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Example 3 was prepared in the same manner as in Example 1, except that the porous carbon particles PC-3 according to Example 3 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Example 3 are summarized in Table 3.

[0155] The obtained porous carbon film had a D band peak half width of 43 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with a moderately low crystallinity, but the crystallinity as a whole was not too low. In addition, the volume of pores with diameters of 1 nm or more and 1000 nm or less was 3.21 cm ３ / g, BET specific surface area is 728 m ２ The physical properties of the porous carbon membrane according to Example 3 are shown in Table 4.

[0156] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Example 3 were produced in the same manner as in Example 1, except that the porous carbon film according to Example 3 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0157] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 10.5 mAh / cm ２ The discharge capacity per mass of the positive electrode was a large value of 2674 mAh / g, and the number of cycles was also high at 38. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0158] Comparative Example 3 <<Preparation of Porous Carbon Particles>> Porous carbon particles CPC-3 according to Comparative Example 3 were prepared in the same manner as in Example 3, except that the secondary heat treatment was not carried out.

[0159] The porous carbon particles CPC-3 according to Comparative Example 3 have a D band peak half width of 183 cm in the Raman spectrum. －１It was found that the crystal disorder was too large. As a result of X-ray diffraction measurement of CPC-3, the chart shown in FIG. 14 was obtained, and one peak indexed to 002 was confirmed at 2θ=23.61 deg. The interplanar spacing d of the (002) plane calculated from this peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in CPC-3 was 3.80 cm ３ / g, the average pore diameter of pores with a diameter of 1 nm to 1000 nm is 16 nm, and the BET specific surface area is 1150 m ２ The physical properties of the porous carbon particles CPC-3 according to Comparative Example 3 are shown in Tables 1 and 2.

[0160] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 3 was prepared in the same manner as in Example 1, except that porous carbon particles CPC-3 according to Comparative Example 3 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Comparative Example 3 are summarized in Table 3.

[0161] The obtained porous carbon film had a D band peak half width of 145 cm in the Raman spectrum. －１ It was found that the porous carbon membrane had excessive crystal disorder. The volume of the pores with diameters of 1 nm to 1000 nm was 3.37 cm ３ / g, BET specific surface area is 967 m ２ The physical properties of the porous carbon membrane according to Comparative Example 3 are shown in Table 4.

[0162] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 3 were produced in the same manner as in Example 1, except that the porous carbon film according to Comparative Example 3 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0163] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 11.7 mAh / cm ２ Although the discharge capacity per mass of the positive electrode was a large value of 2310 mAh / g, the number of cycles was only 20. Table 5 shows the basis weight of the electrode, the discharge capacity, the amount of electrolyte used in preparing the evaluation cell, and the number of cycles.

[0164] [Example 4] <<Preparation of porous carbon particles>> Porous carbon particles PC-4 according to Example 4 were prepared in the same manner as in Example 1, except that the mixing ratio of the phenolic resin to MgO was set to 30:70 by mass.

[0165] The porous carbon particles PC-4 according to Example 4 have a D band peak half width of 46 cm in the Raman spectrum. －１ It was confirmed that the porous carbon particles contained an appropriate amount of crystal disorder, which was within the scope of the present invention. X-ray diffraction measurement of PC-4 yielded the chart shown in FIG. 15, in which two peaks indexed to 002 were observed at 2θ=23.62 deg and 2θ=26.04 deg, respectively. The interplanar spacing d of the (002) plane calculated from each peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in PC-4 was 2.98 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 9 nm, and the BET specific surface area is 1233 m ２ The physical properties of the porous carbon particles PC-4 according to Example 4 are summarized in Tables 1 and 2. The Raman spectrum of the porous carbon particles PC-4 is shown in FIG.

[0166] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Example 4 was prepared in the same manner as in Example 1, except that the porous carbon particles PC-4 according to Example 4 were used as the porous carbon particles and the sheet thickness in the molding step was set to 300 μm. The preparation conditions for the porous carbon membrane according to Example 4 are summarized in Table 3.

[0167] The obtained porous carbon film had a D band peak half width of 44 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with a moderately low crystallinity, but the crystallinity as a whole was not too low. In addition, the volume of pores with a diameter of 1 nm or more and 1000 nm or less was 2.63 cm ３ / g, BET specific surface area is 1004 m ２The physical properties of the porous carbon membrane according to Example 4 are shown in Table 4.

[0168] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Example 4 were produced in the same manner as in Example 1, except that the porous carbon film according to Example 4 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0169] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 12.5 mAh / cm ２ The discharge capacity per mass of the positive electrode was a large value of 1981 mAh / g, and the number of cycles was also high, at 35. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0170] Example 5 <<Preparation of Porous Carbon Particles>> Porous carbon particles PC-5 according to Example 5 were prepared in the same manner as in Example 4, except that the temperature of the secondary heat treatment was set to 2100°C.

[0171] The porous carbon particles PC-5 according to Example 5 have a D band peak half width of 40 cm in the Raman spectrum. －１ It was confirmed that the porous carbon particles had an appropriate amount of crystal disorder within the scope of the present invention. X-ray diffraction measurement of PC-5 resulted in the chart shown in FIG. 17, in which three peaks indexed to 002 were observed at 2θ=24.29 deg, 2θ=25.92 deg, and 2θ=26.49 deg, respectively. The interplanar spacing d of the (002) plane calculated from each peak was ００２ were 0.3661 nm, 0.3435 nm, and 0.3362 nm, respectively. The volume of pores with diameters of 1 nm to 1000 nm in PC-5 was 2.58 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 9 nm, and the BET specific surface area is 1071 m ２ The physical properties of the porous carbon particles PC-5 according to Example 5 are summarized in Tables 1 and 2. The Raman spectrum of the porous carbon particles PC-5 is shown in FIG.

[0172] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Example 5 was prepared in the same manner as in Example 4, except that the porous carbon particles PC-5 according to Example 5 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Example 5 are summarized in Table 3.

[0173] The obtained porous carbon film had a D band peak half width of 53 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with a moderately low crystallinity, but the crystallinity as a whole was not too low. The volume of the pores with a diameter of 1 nm or more and 1000 nm or less was 2.15 cm ３ / g, BET specific surface area is 827 m ２ The physical properties of the porous carbon membrane according to Example 5 are shown in Table 4.

[0174] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Example 5 were produced in the same manner as in Example 1, except that the porous carbon film according to Example 5 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0175] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 7.6 mAh / cm ２ The discharge capacity per mass of the positive electrode was a large value of 1381 mAh / g, and the number of cycles was also high, at 31. Table 5 shows the basis weight of the electrode, the discharge capacity, the amount of electrolyte used in preparing the evaluation cell, and the number of cycles.

[0176] Comparative Example 4 <<Preparation of Porous Carbon Particles>> Porous carbon particles CPC-4 according to Comparative Example 4 were prepared in the same manner as in Example 4, except that the secondary heat treatment was not carried out.

[0177] The porous carbon particles CPC-4 according to Comparative Example 4 have a D band peak half width of 189 cm in the Raman spectrum. －１It was found that the crystal disorder was too large. As a result of X-ray diffraction measurement of CPC-4, the chart shown in FIG. 19 was obtained, and one peak indexed to 002 was confirmed at 2θ=21.85 deg. The interplanar spacing d of the (002) plane calculated from this peak was ００２ In Figure 19, only a broad peak indexed to 002 appears in the range of 16 deg ≤ 2θ ≤ 30 deg, and no sharp peaks appear. This result indicates that there is almost no crystalline carbon confirmed by X-ray diffraction. In addition, the volume of pores in CPC-4 with diameters of 1 nm to 1000 nm is 3.80 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 8 nm, and the BET specific surface area is 1481 m ２ The physical properties of the porous carbon particles CPC-4 according to Comparative Example 4 are summarized in Tables 1 and 2. The results of Raman spectrum measurement of these porous carbon particles are shown in FIG.

[0178] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 4 was prepared in the same manner as in Example 4, except that porous carbon particles CPC-4 according to Comparative Example 4 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Comparative Example 4 are summarized in Table 3.

[0179] The obtained porous carbon film had a D band peak half width of 156 cm in the Raman spectrum. －１ It was found that the porous carbon membrane had excessive crystal disorder. The volume of the pores with diameters of 1 nm to 1000 nm was 3.02 cm ３ / g, BET specific surface area is 1339 m ２ The physical properties of the porous carbon membrane according to Comparative Example 4 are shown in Table 4.

[0180] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 4 were produced in the same manner as in Example 1, except that the porous carbon film according to Comparative Example 4 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0181] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 6.9 mAh / cm ２ Although the discharge capacity per mass of the positive electrode was a large value of 2946 mAh / g, the number of cycles was only 14. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0182] Comparative Example 5 <<Preparation of Porous Carbon Particles>> Porous carbon particles CPC-5 according to Comparative Example 5 were prepared in the same manner as in Example 4, except that the temperature of the secondary heat treatment was set to 1600°C.

[0183] The porous carbon particles CPC-5 according to Comparative Example 5 have a D band peak half width of 64 cm in the Raman spectrum. －１ It was found that the crystal disorder was too large. As a result of X-ray diffraction measurement of CPC-5, the chart shown in FIG. 21 was obtained, and one peak indexed to 002 was confirmed at 2θ=24.04 deg. The interplanar spacing d of the (002) plane calculated from this peak was ００２ In Figure 21, only a broad peak indexed to 002 appears in the range of 16 deg ≦ 2θ ≦ 30 deg, and no sharp peaks appear. This result indicates that there is almost no crystalline carbon confirmed by X-ray diffraction. In addition, the volume of pores in CPC-5 with diameters of 1 nm to 1000 nm is 3.45 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 8 nm, and the BET specific surface area is 1652 m ２ The physical properties of the porous carbon particles CPC-5 according to Comparative Example 5 are summarized in Tables 1 and 2. The results of Raman spectrum measurement of these porous carbon particles are shown in FIG.

[0184] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 5 was prepared in the same manner as in Example 4, except that porous carbon particles CPC-5 according to Comparative Example 5 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Comparative Example 5 are summarized in Table 3.

[0185] The obtained porous carbon film had a D band peak half width of 64 cm in the Raman spectrum. －１ It was found that the porous carbon membrane had excessive crystal disorder. The volume of the pores with diameters of 1 nm to 1000 nm was 2.93 cm ３ / g, BET specific surface area is 1361 m ２ The physical properties of the porous carbon membrane according to Comparative Example 5 are shown in Table 4.

[0186] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 5 were produced in the same manner as in Example 1, except that the porous carbon membrane according to Comparative Example 5 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0187] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 8.4 mAh / cm ２ Although the discharge capacity per mass of the positive electrode was a large value of 1950 mAh / g, the number of cycles was only 22. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0188] Comparative Example 6 <<Preparation of Porous Carbon Particles>> Porous carbon particles CPC-6 according to Comparative Example 6 were prepared in the same manner as in Example 4, except that the temperature of the secondary heat treatment was set to 2400°C.

[0189] The porous carbon particles CPC-6 according to Comparative Example 6 have a D band peak half width of 38 cm in the Raman spectrum. －１ Although this was within the specified range, the half width of the G band peak in the Raman spectrum was 30 cm －１ The R value was 0.56, which was smaller than the predetermined range, and it was found that the crystal disorder was too small. As a result of X-ray diffraction measurement of CPC-6, the chart shown in Figure 23 was obtained, and three peaks indexed to 002 were confirmed at 2θ = 25.34 deg, 2θ = 25.97 deg, and 2θ = 26.48 deg, respectively. The interplanar spacing d of the (002) plane calculated from each peak was ００２were 0.3513 nm, 0.3428 nm, and 0.3364 nm, respectively. In Figure 23, the peak intensity indexed to 002 is significantly larger than that of the porous carbon particles PC-5 according to Example 5 shown in Figure 17. This result indicates that the carbon particles CPC-6 according to this comparative example have an excessive amount of crystalline carbon. In addition, the volume of pores with diameters of 1 nm or more and 1000 nm or less in CPC-6 is 1.42 cm ３ / g, and the BET specific surface area is only 335 m ２ / g. The average pore size of the pores having a diameter of 1 nm or more and 1000 nm or less in the porous carbon particles CPC-6 according to Comparative Example 6 was 15 nm. The physical properties of the porous carbon particles CPC-6 according to Comparative Example 6 are summarized in Tables 1 and 2. The Raman spectrum of these porous carbon particles is shown in FIG. 24.

[0190] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 6 was prepared in the same manner as in Example 4, except that porous carbon particles CPC-6 according to Comparative Example 6 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Comparative Example 6 are summarized in Table 3.

[0191] The obtained porous carbon film had a D band peak half width of 36 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane had relatively high crystallinity. The volume of the pores with diameters of 1 nm to 1000 nm was 1.19 cm ３ / g, BET specific surface area is 269 m ２ / g, which was quite small. Furthermore, the apparent density was 0.22 g / cm ３ The physical properties of the porous carbon membrane according to Comparative Example 6 are summarized in Table 4.

[0192] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 6 were produced in the same manner as in Example 1, except that the porous carbon film according to Comparative Example 6 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0193] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 6.1 mAh / cm ２ The discharge capacity per positive electrode mass was as low as 1160 mAh / g. This is thought to be because the positive electrode had a small porosity and a small specific surface area, making it difficult for reactions to occur at the positive electrode during discharge. The number of cycles was also low, at 8. This is thought to be due to the high crystallinity of the porous carbon particles contained in the positive electrode, which resulted in poor affinity between the pore surface of the positive electrode and the electrolyte. Table 5 summarizes the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0194] Example 6 Preparation of Porous Carbon Membrane A porous carbon membrane according to Example 6 was prepared in the same manner as in Example 1, except that the blending ratio of the porous carbon particles PC-1 was 65 parts by mass and the blending ratio of PAN was 25 parts by mass when preparing the mixture slurry. The preparation conditions for the porous carbon membrane according to Example 6 are summarized in Table 3.

[0195] The obtained porous carbon film had a D band peak half width of 61 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with a moderately low crystallinity, but the crystallinity as a whole was not too low. In addition, the volume of pores with diameters of 1 nm or more and 1000 nm or less was 1.44 cm ３ / g, BET specific surface area is 1038 m ２ The physical properties of the porous carbon membrane of Example 6 are shown in Table 4.

[0196] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Example 6 were produced in the same manner as in Example 1, except that the porous carbon film according to Example 6 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0197] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 9.1 mAh / cm ２The discharge capacity per mass of the positive electrode was a large value of 1,330 mAh / g, and the number of cycles was also high, at 39. Table 5 shows the basis weight of the electrode, the discharge capacity, the amount of electrolyte used in preparing the evaluation cell, and the number of cycles.

[0198] Example 7 Preparation of Porous Carbon Membrane A porous carbon membrane according to Example 7 was prepared in the same manner as in Example 2, except that the blending ratio of the porous carbon particles PC-2 was 55 parts by mass and the blending ratio of PAN was 35 parts by mass when preparing the mixture slurry. The preparation conditions for the porous carbon membrane according to Example 7 are summarized in Table 3.

[0199] The obtained porous carbon film had a D band peak half width of 62 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with a moderately low crystallinity, but the crystallinity as a whole was not too low. The volume of the pores with a diameter of 1 nm or more and 1000 nm or less was 1.96 cm ３ / g, BET specific surface area is 826 m ２ The physical properties of the porous carbon membrane of Example 7 are shown in Table 4.

[0200] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Example 7 were produced in the same manner as in Example 1, except that the porous carbon film according to Example 7 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0201] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 5.9 mAh / cm ２ The discharge capacity per mass of the positive electrode was a large value of 1,380 mAh / g, and the number of cycles was also high, at 37. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0202] Example 8 Preparation of Porous Carbon Particles Porous carbon particles PC-8 according to Example 8 were prepared in the same manner as in Example 3, except that polyvinyl alcohol (PVA) was used as the organic resin and the mixing ratio of PVA to MgO was 40:60 by mass.

[0203] The porous carbon particles PC-8 according to Example 8 have a D band peak half width of 40 cm in the Raman spectrum. －１ It was confirmed that the porous carbon particles had an appropriate amount of crystal disorder within the scope of the present invention. As a result of the X-ray diffraction measurement, the chart shown in Figure 25 was obtained, and two peaks indexed to 002 were confirmed at 2θ = 24.76 deg and 2θ = 25.80 deg, respectively. The interplanar spacing d of the (002) plane calculated from each peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in PC-8 was 5.41 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 27 nm, and the BET specific surface area is 779 m ２ The physical properties of the porous carbon particles PC-8 according to Example 8 are shown in Tables 1 and 2.

[0204] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Example 8 was prepared in the same manner as in Example 1, except that the porous carbon particles PC-8 according to Example 8 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Example 8 are summarized in Table 3.

[0205] The obtained porous carbon film had a D band peak half width of 42 cm in the Raman spectrum. －１ It was confirmed that the porous carbon membrane contained porous carbon particles with a moderately low crystallinity, but the crystallinity as a whole was not too low. The volume of the pores with a diameter of 1 nm or more and 1000 nm or less was 3.01 cm. ３ / g, BET specific surface area is 536 m ２ The physical properties of the porous carbon membrane of Example 8 are shown in Table 4.

[0206] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Example 8 were produced in the same manner as in Example 1, except that the porous carbon membrane according to Example 8 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0207] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 9.9 mAh / cm ２ The discharge capacity per mass of the positive electrode was a large value of 1877 mAh / g, and the number of cycles was also high, at 38. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0208] Comparative Example 7 <<Preparation of Porous Carbon Particles>> Porous carbon particles CPC-7 according to Comparative Example 7 were prepared in the same manner as in Example 8, except that the secondary heat treatment was not carried out.

[0209] The porous carbon particles CPC-7 according to Comparative Example 7 have a D band peak half width of 230 cm in the Raman spectrum. －１ As a result of X-ray diffraction measurement of CPC-7, the chart shown in FIG. 26 was obtained, in which one peak indexed to 002 was confirmed at 2θ=24.39 deg. The interplanar spacing d of the (002) plane calculated from this peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in CPC-7 was 3.87 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 21 nm, and the BET specific surface area is 796 m ２ The physical properties of the porous carbon particles CPC-7 according to Comparative Example 7 are shown in Tables 1 and 2.

[0210] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 7 was prepared in the same manner as in Example 1, except that porous carbon particles CPC-7 according to Comparative Example 7 were used as the porous carbon particles and the sheet thickness in the molding step was set to 550 μm. The preparation conditions for the porous carbon membrane according to Comparative Example 7 are summarized in Table 3.

[0211] The obtained porous carbon film had a D band peak half width of 172 cm in the Raman spectrum. －１ It was found that the porous carbon membrane had excessive crystal disorder. The volume of the pores with diameters of 1 nm to 1000 nm was 3.44 cm ３ / g, BET specific surface area is 642 m２ The physical properties of the porous carbon membrane according to Comparative Example 7 are shown in Table 4.

[0212] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 7 were produced in the same manner as in Example 1, except that the porous carbon film according to Comparative Example 7 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0213] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 9.5 mAh / cm ２ Although the discharge capacity per positive electrode mass was a large value of 2678 mAh / g, the number of cycles was only 24. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0214] Comparative Example 8 Ketjenblack (registered trademark) EC600JD (manufactured by Lion Specialty Chemicals) was used as the porous carbon particles KB. These porous carbon particles have a D band peak half width of 105 cm in the Raman spectrum. －１ As a result of X-ray diffraction measurement of KB, the chart shown in FIG. 27 was obtained, and one peak indexed to 002 was confirmed at 2θ=24.64 deg. The interplanar spacing d of the (002) plane calculated from this peak was ００２ The volume of pores with diameters of 1 nm to 1000 nm in KB was 3.55 cm ３ / g, the average pore diameter of pores with diameters of 1 nm to 1000 nm is 12 nm, and the BET specific surface area is 1328 m ２ The physical properties of the porous carbon particles KB according to Comparative Example 8 are summarized in Tables 1 and 2. The results of Raman spectrum measurement of the porous carbon particles KB are shown in FIG.

[0215] <<Preparation of porous carbon membrane>> A porous carbon membrane according to Comparative Example 8 was prepared in the same manner as in Comparative Example 7, except that the porous carbon particles KB according to Comparative Example 8 were used as the porous carbon particles. The preparation conditions for the porous carbon membrane according to Comparative Example 8 are summarized in Table 3.

[0216] The obtained porous carbon film had a D band peak half width of 90 cm in the Raman spectrum. －１ It was found that the porous carbon membrane had excessive crystal disorder. The volume of the pores with diameters of 1 nm to 1000 nm was 3.36 cm ３ / g, BET specific surface area is 1022 m ２ The physical properties of the porous carbon membrane according to Comparative Example 8 are shown in Table 4.

[0217] <Discharge Capacity and Cycle Characteristics of Air Battery> A coin cell 800 and a cell 200 for evaluating cycle characteristics according to Comparative Example 8 were produced in the same manner as in Example 1, except that the porous carbon membrane according to Comparative Example 8 was used for the positive electrode, and the discharge capacity and cycle characteristics were evaluated.

[0218] [Correction based on Rule 91 12.11.2024] As a result, the discharge capacity per positive electrode area was 17.3 mAh / cm ２ Although the discharge capacity per mass of the positive electrode was a large value of 2671 mAh / g, the number of cycles was only 26. Table 5 shows the electrode basis weight, discharge capacity, amount of electrolyte used in preparing the evaluation cell, and number of cycles.

[0219]

[0220] [Amendment under Rule 91 12.11.2024]

[0221]

[0222]

[0223]

[0224] According to the present invention, an air battery having a large discharge capacity and excellent cycle characteristics can be obtained. Therefore, the present invention is useful in that it can provide an air battery that is more resistant to repeated charge and discharge than conventional batteries.

[0225] [Correction based on Rule 91 12.11.2024] 600 Coin cell 610 Anode structure 620 Cathode structure 630 Coin cell type restraining device 635 Current collector 640 Metal layer 650 Spacer 660 Separator 670 Space (space for electrolyte filling) 680 Metal mesh 685 Gasket 690 Porous carbon membrane electrode 100 Anode structure 500 Stacked-type air battery 510 Cathode structure 520 Anode current collector 525 Cathode current collector 540 Separator 550 Porous carbon membrane electrode 560 Gas diffusion layer 800 (CR2032 type) Coin cell 810 Cathode can 815 Anode can 820 Metal mesh 830 Gas diffusion layer 840 Cathode (porous carbon membrane) 850 Separator 860 Anode (metal layer) 870 Spacer 875 Disc spring 880 Gasket 200 Cell for evaluating cycle characteristics 101 Positive electrode (porous carbon membrane) 102 Gas diffusion layer 103 Positive electrode current collector 104 Negative electrode structure 105 Negative electrode (metallic lithium) 106 Negative electrode current collector 107 Non-aqueous electrolyte layer 108 Solid electrolyte membrane 109 Separator 110 Glass plate 111 Stainless steel plate 112 Fixing screw 113 Fixing washer 114 Support 115 Spring 116 Spacer 118 Positive electrode structure

Claims

1. [Correction based on Rule 91 12.11.2024] Porous carbon particles for forming a porous carbon membrane used for the positive electrode of an air battery, which meets all of the following a) to g): a) The half-width of the D band peak in the Raman spectrum is 30 cm －１ 60cm or more －１ b) The half-width of the G band peak in the Raman spectrum is 32 cm or less. －１ 80cm or more －１ c) The ratio of the intensity of the D-band peak to the intensity of the G-band peak in a Raman spectrum, R, is 0.8 or more. d) The lattice spacing d between the (002) planes of carbon measured by X-ray diffraction (XRD) is 0.8 or more. ００２ e) The volume of pores having a diameter of 1 nm or more and 1000 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 1.5 cm ３ / g or more 10.0cm ３ f) The volume of pores having a diameter of 1 nm or more and 100 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 1.0 cm ３ / g or more 8.0cm ３ g) The specific surface area, as determined by the BET method from an adsorption isotherm obtained by a nitrogen adsorption method, is 500 cm ２ / g or more 2000cm ２ / g or less.

2. A porous carbon membrane for a positive electrode of an air battery, comprising the porous carbon particles according to claim 1 and satisfying all of the following A) to D): A) the half-width of the D band peak in the Raman spectrum is 64 cm －１ B) The volume of pores having a diameter of 1 nm or more and 1000 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is less than 1.2 cm ３ / g or more 8.0cm ３ C) The volume of pores having a diameter of 1 nm or more and 100 nm or less, as determined by the BJH method from an adsorption isotherm obtained by a nitrogen adsorption method, is 0.8 cm ３ / g or more 7.0cm ３ / g or less. D) The specific surface area, as determined by the BET method from an adsorption isotherm obtained by a nitrogen adsorption method, is 400 cm ２ / g or more 2000cm ２ / g or less.

3. The half-width of the D band peak in the Raman spectrum is 37 cm －１ The porous carbon membrane according to claim 2 .

4. Apparent density is 0.10 g / cm ３ 0.20cm or more ３ The porous carbon membrane according to claim 2 or 3, wherein the molecular weight is 1 / g or less.

5. The porous carbon membrane according to any one of claims 2 to 4, having a porosity of 85% or more and 99% or less.

6. An air battery comprising the porous carbon membrane according to any one of claims 2 to 5 as a positive electrode.

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