Porous carbon material, storage battery using porous carbon material, power-generating device using porous carbon material, and method for producing porous carbon material

Abstract

This porous carbon material contains a calcined body. The specific surface area of the calcined body is 500 to 3,000 m2 / g. The pore diameter of the calcined body is 100 nm or less. The nitrogen content of the calcined body is 1 to 15 at% and the balance of the calcined body is carbon. The biomass degree of the calcined body is within a range from 5 to 100 pMC, and the biomass degree is represented by the ratio of the 14C concentration (14C / 12C) of the calcined body as measured by accelerator mass spectroscopy (AMS) to the 14C concentration (14C / 12C) of a standard sample not derived from fossil fuels.

Description

Porous carbon material, power storage / power generation device using same, and method for producing porous carbon material

[0001] The present disclosure relates to a porous carbon material, an electricity storage / power generation device using the same, and a method for producing the porous carbon material.

[0002] To achieve carbon neutrality, there is a strong demand for improved performance and widespread use of energy storage devices such as secondary batteries and capacitors, and power generation devices such as fuel cells and solar cells. The performance of these energy devices is often determined by the performance of the electrode materials. Carbon materials are promising as electrodes, but they require both economic viability and control technologies for crystallinity, conductivity, porosity, and the amount of surface functional groups. In particular, porosity, or the size of the specific surface area, is an important factor for carbon materials used in electrochemical devices.

[0003] There are two main known methods for producing porous carbon materials: a method using a template and a method not using a template.

[0004] Activated carbon is a typical example of a porous carbon material that does not use a template. For example, coconut shell-derived activated carbon is obtained by calcining and carbonizing the shell (endocarp), which has a relatively high porosity, and then activating it with chemicals, steam, or the like (see, for example, Patent Document 1). However, the large number of functional groups, such as hydrogen and oxygen atoms, present on the surface of the activated carbon can cause side reactions during the operation of energy devices, which can affect the long-term reliability of the devices.

[0005] As a porous carbon material using a template, there is one that is produced by calcining a plant-based raw material such as rice straw or wheat straw to remove inorganic template components such as silica (see, for example, Patent Document 2). However, because natural inorganic components are used as templates, it has been difficult to obtain a porous carbon material with a desired pore size distribution. In addition, there is a problem that a large amount of waste liquid is generated by alkali or acid treatment to remove the silica remaining after calcination.

[0006] Another type of porous carbon material is obtained by calcining and carbonizing a mixture of a synthetic polymer serving as a carbon source and a template material, followed by removing the template. Templates include soft templates such as surfactants and hard templates using nanoparticles of metal oxides such as silica, alumina, and magnesia (see, for example, Patent Documents 3 and 4). In the method using a surfactant as a template, the micelles formed by the surfactant are thermally unstable, and the micellar structure is destroyed during the heating process, making it difficult to control the pore size uniformly.

[0007] On the other hand, metal oxide nanoparticles are thermally stable, making it relatively easy to control the pore size uniformly, but like natural silica, they require alkaline or acid washing. Furthermore, because they use synthetic polymers as the carbon source, the use of fossil fuel-free raw materials is an issue from the perspectives of carbon footprint and LCA (Life Cycle Assessment).

[0008] Japanese Patent No. 5168585 Japanese Patent Application Laid-Open No. 2021-38103 Japanese Patent Application Laid-Open No. 2019-102711 Japanese Patent Application Laid-Open No. 2021-084819

[0009] The porous carbon material according to one embodiment of the present disclosure has a specific surface area of ​​500 to 3000 m ２ / g, pore diameter of 100 nm or less, nitrogen content of 1 to 15 atomic %, and the balance being carbon, and the calcined body when measured by accelerator mass spectrometry (AMS method) １４ C concentration ( １４ C / １２ C) Non-fossil fuel-derived standard sample １４ C concentration ( １４ C / １２ C) is in the range of 5 to 100 pMC.

[0010] A method for producing a porous carbon material according to one embodiment of the present disclosure includes: (1) a step of preparing a precursor raw material by mixing, foaming, and dispersing a dispersion medium, a nitrogen-containing biomass raw material, and metal oxide nanoparticles having a number average particle size of 100 nm or less as a template; (2) a step of calcining the precursor raw material and graphitizing it to obtain a calcined body; and (3) a step of removing the metal oxide nanoparticles from the calcined body to obtain a porous carbon material.

[0011] (1) to (3) are schematic diagrams for explaining the manufacturing method of the porous carbon materials according to Examples 1 to 10 and Comparative Examples 1 and 2 in the first embodiment. (1) to (3) are schematic diagrams for explaining the manufacturing method of the porous carbon materials according to Examples 11 and 12 and Comparative Example 3 in the first embodiment. A table showing the relationship between the particle size and the name of the pore size in the IUPAC classification. A schematic cross-sectional view showing the micropores, mesopores, and macropores present in the cross section of the porous carbon material according to the first embodiment. Table 1 showing the raw materials, manufacturing conditions, and evaluation results of Examples 1 to 12 and Comparative Examples 1 to 3.

[0012] Because biomass such as rice husks uses natural inorganic components as a template, the microstructure of the resulting porous carbon material is non-uniform, and the large amount of alkaline and acidic waste liquid generated to remove the natural silica from the template is a problem. When metal oxide nanoparticles are used as templates, the generation of large amounts of waste liquid is also a problem. The challenge is to simultaneously establish technology for precise control of the pore size of porous carbon materials and develop an environmentally friendly production process using biomass raw materials.

[0013] The present inventors have found that a nitrogen-doped porous carbon material can be easily obtained by mixing a dispersion medium, a nitrogen-rich biomass raw material as an organic precursor raw material, and metal oxide nanoparticles as a template, followed by foaming, uniform dispersion, firing, and removing the template from the fired body, and have arrived at a porous carbon material and a method for producing the same according to one embodiment of the present disclosure.

[0014] An object of the present disclosure is to provide an environmentally friendly porous carbon material made from biomass raw materials.

[0015] According to the porous carbon material and the method for producing the same disclosed herein, a nitrogen-containing porous carbon material with a large specific surface area, which has previously been difficult to obtain quickly and inexpensively, can be easily obtained by an environmentally friendly process using nitrogen-containing biomass raw materials that are abundant in nature and metal oxide nanoparticles.

[0016] The porous carbon material according to the first aspect includes a fired body, and the fired body has a specific surface area of ​​500 to 3000 m ２ / g, the pore size of the fired body is 100 nm or less, the nitrogen content of the fired body is 1 to 15 atomic %, the remainder of the fired body is carbon, the biomass degree of the fired body is in the range of 5 to 100 pMC, and the biomass degree of the fired body when measured by accelerator mass spectrometry (AMS method) is １４ C concentration ( １４ C / １２ C) Non-fossil fuel-derived standard sample １４ C concentration ( １４ C / １２ C) is expressed as a percentage of the

[0017] The porous carbon material according to a second aspect may be the porous carbon material according to the first aspect, wherein the pore diameter includes micropores having a diameter of 2 nm or less and mesopores having a diameter of 2 nm or more and 50 nm or less.

[0018] The porous carbon material according to a third aspect may be the porous carbon material according to the second aspect, wherein the pore diameters may further include macropores having a diameter of 100 nm or more.

[0019] An electrode according to a fourth aspect includes the porous carbon material according to any one of the first to third aspects.

[0020] A device for storing or generating electricity according to a fifth aspect includes the electrode according to the fourth aspect.

[0021] The method for producing a porous carbon material according to the sixth aspect includes the steps of: (1) preparing a precursor raw material by mixing, foaming, and dispersing a dispersion medium, a nitrogen-containing biomass raw material, and metal oxide nanoparticles serving as a template having a number average particle size of 100 nm or less; (2) calcining the precursor raw material to graphitize it and obtain a calcined body; and (3) removing the metal oxide nanoparticles from the calcined body to obtain a porous carbon material.

[0022] A seventh aspect of the method for producing a porous carbon material is the same as the sixth aspect, wherein the metal oxide nanoparticles serving as the template may be ZnO particles.

[0023] The method for producing a porous carbon material according to an eighth aspect is the method for producing a porous carbon material according to the sixth or seventh aspect, wherein the nitrogen-containing biomass raw material may be at least one selected from the group consisting of natural sugars, proteins, and nucleic acids.

[0024] A ninth aspect of the method for producing a porous carbon material is any one of the sixth to eighth aspects, wherein the nitrogen-containing biomass raw material may be at least one selected from the group consisting of gelatin, chitin, chitosan, glucosamine, deoxyribonucleic acid (DNA), and ribonucleic acid (RNA).

[0025] A tenth aspect of the present invention is a method for producing a porous carbon material, in any one of the sixth to ninth aspects, wherein the biomass degree of the nitrogen-containing biomass raw material is in the range of 5 to 100 pMC, and the biomass degree of the nitrogen-containing biomass raw material is measured by accelerator mass spectrometry (AMS). １４ C concentration ( １４ C / １２ C) Non-fossil fuel-derived standard sample １４ C concentration ( １４ C / １２ C) may be expressed as a percentage of the total amount of the saturation agent.

[0026] The method for producing a porous carbon material according to an eleventh aspect is the method of any one of the sixth to tenth aspects, in which metal compound particles other than oxides may be added as the precursor raw material.

[0027] A twelfth aspect of the present invention relates to a method for producing a porous carbon material according to the eleventh aspect of the present invention, wherein the metal compound particles are ZnCl ２ It may also be a particle.

[0028] A porous carbon material and a method for producing the same according to an embodiment will be described below.

[0029] First Embodiment <Porous Carbon Material> The porous carbon material according to the first embodiment of the present disclosure has a specific surface area of ​​500 to 3000 m ２ / g, pore diameter of 100 nm or less, nitrogen content of 1 to 15 atomic %, and the balance being carbon. １４ C concentration ( １４ C / １２ C) Non-fossil fuel-derived standard sample １４ C concentration ( １４ C / １２ C) is in the range of 5 to 100 pMC.

[0030] The porous carbon material can be obtained by heating and firing a mixture of nitrogen-containing biomass raw material as an organic substance and metal oxide nanoparticles that serve as templates. The method for removing the template varies depending on the type of oxide nanoparticles, but the porous carbon material obtained after template removal contains 1 to 15% nitrogen atoms derived from the raw material and has a specific surface area of ​​500 to 3,000 m. ２ / g, and has structural characteristics suitable for use as an electrode material in energy devices.

[0031] One of the features of the porous carbon material of this embodiment is that it is produced from a biomass raw material. The fact that the carbon contained in the skeleton of the obtained porous carbon material is derived from biomass is due to the fact that it is radiocarbon. １４ This can be confirmed by radiocarbon measurements. １４ C can be analyzed by using, for example, accelerator mass spectrometry (AMS).

[0032] １４ One of the characteristics of C is that it is a radioactive isotope, which decays into nitrogen ( １４ On Earth, minute amounts of cosmic rays constantly fall from the atmosphere. １４ C is generated. １４ C is carbon dioxide １４ CO ２ After being oxidized and dispersed into the atmosphere, it is taken up by plants and animals through the food chain, and disappears according to its half-life as it circulates through the environment via the food chain. This phenomenon is used to measure the age of the material. On the other hand, human activities since the Industrial Revolution have １４ This causes fluctuations in the C cycle. １４ The use of fossil fuels such as oil and coal that do not contain carbon (called dead carbon) １４ While reducing the C concentration, the atmospheric nuclear tests conducted over a period of about 10 years from the 1950s １４ The production of Bomb C in the atmosphere １４ ​As a result, the carbon derived from living organisms that have existed since 1950 is called modern carbon, and is thousands of times more abundant than fossil fuels. １４ Contains C.

[0033] Modern carbon from biomass is approximately 1.2 x 10 －１２ of １４ C / １２ C ratio, and the carbon derived from fossil fuels, dead C, is 1.0 x 10 －１６ below １４ C / １２ This knowledge can be used to determine whether the carbon atoms in the skeletal structure are derived from biomass.

[0034] For example, since synthetic polymers such as polyvinyl alcohol (PVA) are made from fossil fuels, when this is used as a raw material as an organic precursor, the biomass degree of the resulting porous carbon material is 0 pMC, whereas the biomass degree of a porous carbon material obtained using only biomass raw materials is 100 pMC. The unit of biomass degree is pMC (percent modern carbon), and the higher this value, the higher the biomass degree.

[0035] <Pore characteristics of porous carbon material> Fig. 2A is a table showing the relationship between particle size and name of pore size in the IUPAC classification, and Fig. 2B is a schematic cross-sectional view showing micropores, mesopores, and macropores present in a cross section of the porous carbon material according to embodiment 1.

[0036] The specific surface area of ​​the porous carbon material is 500 to 3000 m ２ / g is preferable, and 1000 to 3000m ２ It is more preferable that the SiO2 content is 1 / g.

[0037] The specific surface area of ​​the porous carbon material is determined based on JIS Z 8830:2013. ２ It can be determined by gas adsorption measurement. ２ By performing a BET plot analysis on the desorption side of the gas adsorption / desorption isotherm, the N required to form a monolayer was determined. ２ The amount of gas (=specific surface area) is calculated.

[0038] The average pore size distribution of the porous carbon material preferably contains micropores (up to 2 nm) and mesopores (2 to 50 nm) as shown in FIG. 2B, but may also contain macropores of 100 nm or less.

[0039] The average pore size distribution of the porous carbon material was also determined based on JIS Z 8830:2013. ２ It is determined by gas adsorption measurement, specifically, N ２ It is calculated from BJH analysis or DMF analysis of the gas adsorption / desorption isotherm.

[0040] <Electrode Containing Porous Carbon Material> The electrode according to the first embodiment contains the porous carbon material described above.

[0041] The porous carbon material according to the first embodiment has a specific surface area of ​​500 to 3000 m obtained by firing at least a nitrogen-containing biomass raw material. ２ The porous carbon material of the present invention is a fired body having a carbon content of 1000 kJ / g, a pore diameter of 100 nm or less, a nitrogen content of 1 to 15%, and a biomass degree of 5 to 100 pMC as measured by accelerator mass spectrometry (AMS). Therefore, the porous carbon material of the present invention is suitable for a wide range of applications, for example, as an electrode material for electricity storage devices such as lithium ion secondary batteries and electric double layer capacitors, and for power generation devices such as fuel cells and solar cells.

[0042] <Raw Material for Porous Carbon Material: Nitrogen-Containing Biomass as Organic Precursor> From the viewpoints of carbon footprint and LCA (Life Cycle Assessment), the organic precursor raw material for the porous carbon material according to the first embodiment is preferably nitrogen-containing biomass, and is preferably at least one selected from the group consisting of natural sugars, proteins, and nucleic acids. Specifically, it is preferably at least one selected from the group consisting of gelatin, chitin, chitosan, glucosamine, deoxyribonucleic acid (DNA), and ribonucleic acid (RNA), which are relatively inexpensive and readily available. For example, gelatin is a natural polymer with an average molecular weight of approximately 80,000 and is known as a naturally abundant and sustainable animal derivative. Gelatin forms a triple helix structure. When heated, the helix structure unravels, the molecules become random coils, and form a sol. When cooled, this forms a three-dimensional network structure, turning into a gel.

[0043] <Raw material for porous material: metal oxide nanoparticles as template> The type of template raw material for the porous carbon material according to the first embodiment may be any known template material, whether organic or inorganic. However, from the viewpoint of precise control of pore size, it is preferable to use thermally stable metal oxide nanoparticles, which do not change shape even at high temperatures. For example, zeolite, SiO ２ , Al ２ O ３ , Fe ２ O ３ , MgO, CuO, CeO ２ , Y ２ O ３ Known common metal oxides such as ZnO can be used.

[0044] The shape of the template is not particularly limited and may be any shape, such as spherical, elliptical, cubic, rectangular, cylindrical, or conical. However, from an economical viewpoint, spherical or elliptical shapes are preferred because they generally produce metal oxide nanoparticles with spherical or elliptical shapes.

[0045] From the viewpoint of controlling the pore size distribution of the porous carbon material, the particle size distribution of the template is preferably nanoparticles with a diameter D50 of 100 nm or less, and furthermore, in order to increase the specific surface area, it is more preferable that the nanoparticles have a D50 of 50 nm or less.

[0046] <Raw material for porous material: metal compound particles as additives> In addition to the metal oxide nanoparticles, metal compound particles other than oxides may be added. These materials generate metal oxides during the firing process and provide the above-mentioned template effect. At the same time, O ２ can be recovered, so the raw material CO ２ The compound may be selected from the group consisting of carbonates, chlorides, nitrides, sulfides, sulfates, hydroxides, and the like.

[0047] <Method for producing porous carbon material> A method for producing a porous carbon material 109 according to the first embodiment will be described with reference to Fig. 1A. The method for producing the porous carbon material 109 includes steps (1) to (3).

[0048] (1) Preparing step of precursor material 105: A dispersion medium 101, at least one kind of nitrogen-containing biomass material 102, and metal oxide nanoparticles 103 having a number average particle size of 100 nm or less as a template are mixed, foamed, and dispersed in a mixing, foaming, and dispersing step 104 to prepare precursor material 105.

[0049] (2) Step of Graphitizing the Precursor Material 105: The precursor material is calcined in the calcination step 107 to be graphitized and obtain a calcined body.

[0050] (3) Step of Removing Metal Oxide Nanoparticles 103: The metal oxide nanoparticles are washed from the fired body in a washing step 108 to obtain a porous carbon material 109.

[0051] Each step is described in detail below.

[0052] (1) Preparing Process for Precursor Raw Material 105: (1) in FIG. 1A is a diagram illustrating the preparing process. Dispersion medium 101, nitrogen-containing biomass material 102, and metal oxide nanoparticles 103 are mixed, foamed, and dispersed in mixing / foaming / dispersing process 104 to prepare precursor raw material 105. There are no limitations on the mixing method or order so that nitrogen-containing biomass material 102 and metal oxide nanoparticles 103 are uniformly mixed and dispersed. For example, a mixed liquid of nitrogen-containing biomass material 102 and dispersion medium 101 may be prepared in advance, and a mixed liquid of metal oxide nanoparticles 103 and dispersion medium 101 may be prepared separately, and the two mixed liquids may be mixed last. Furthermore, to achieve uniform dispersion, the mixed liquid may be foamed using a hand mixer or the like.

[0053] From the standpoints of productivity and economy, it would be ideal to obtain a porous carbon material with uniform pore size by complete "solid-phase synthesis" without adding a dispersion medium 101. However, without the dispersion medium 101, it is difficult to uniformly mix and disperse the metal oxide nanoparticles 103 in the organic matrix. In fact, when gelatin and ZnO nanoparticles are used alone without adding water, the metal oxide nanoparticles 103 aggregate and become unevenly distributed, resulting in many areas where pores are not formed and a small specific surface area. Therefore, it is preferable to add even a small amount of dispersion medium 101. Because the nitrogen-containing biomass material 102 is hydrophilic, water is preferred as the dispersion medium 101. When the nitrogen-containing biomass material 102 is gelatin, the raw material blending ratio (weight ratio) is preferably, for example, gelatin:water:metal oxide nanoparticles = 1:0.3 to 1:8 to 30.

[0054] On the other hand, with regard to raw materials other than gelatin, for example, chitin can be mixed well and uniformly with ZnO nanoparticles without the need for a dispersion medium, forming pores with a diameter of 1000 mm. ２ / g or more, the addition of the dispersion medium 101 is not necessarily required depending on the raw material. When the nitrogen-containing biomass raw material 102 is other than gelatin, the raw material blending ratio (weight ratio) is preferably, for example, nitrogen-containing biomass raw material (other than gelatin):water:metal oxide nanoparticles=1:0.3-1:0-30.

[0055] (2) Graphitization Step of Precursor Raw Material 105: (2) in FIG. 1A is a diagram for explaining the graphitization step.

[0056] When the precursor raw material 105 contains gelatin, freezing it at −15°C or below for one day or more before firing is advantageous for increasing the specific surface area. This is due to the molecular structure of gelatin, where freezing promotes the formation of a three-dimensional network structure. The randomly coiled gelatin molecular chains in the precursor raw material 105 stage self-organize to form a three-dimensional helical structure when frozen, and this structure is thought to play an important role in the formation of a mesoporous structure during heating and firing. In the freezing step 106, the precursor raw material 105 may be frozen by slow cooling in a freezer or by rapid cooling with liquid nitrogen or the like. The cooling rate until freezing is not particularly limited, but a rate of 1 to 100°C / min is preferred. Furthermore, the frozen storage time is preferably 1 to 7 days in a freezer and 0.01 to 1 day when rapidly cooled with liquid nitrogen.

[0057] This precursor raw material 105 is calcined in a calcination step 107 to obtain a porous carbon material 109. The calcination step 107 is performed in an inert gas atmosphere at a temperature range of 950 to 1200°C to burn off foreign elements (hydrogen, oxygen, nitrogen, etc.) other than carbon contained in the nitrogen-containing biomass raw material 102. There are no particular restrictions on the temperature rise rate, but a rate of 1 to 50°C / min is acceptable, although from the viewpoint of productivity, a rate of 20 to 50°C / min is preferred. The calcination time is preferably 1 to 10 hours, and more preferably 3 to 6 hours from the viewpoints of the residual rate of foreign elements and productivity.

[0058] (3) Step of Removing Metal Oxide Nanoparticles 103: (3) in FIG. 1A is a diagram for explaining the removal step.

[0059] When ZnO nanoparticles are used as the template, thermal reduction by carbon proceeds in the firing process (2), and ZnO turns into metallic Zn. This metallic Zn evaporates at around 906 to 907°C, so the template does not remain. In other words, only when ZnO nanoparticles are used, the cleaning step 108 in which the template is dissolved and cleaned using an acid or alkali is not necessary, and the porous carbon material 109 can be obtained without the cleaning step 108.

[0060] In addition, SiO other than ZnO ２ , Al ２ O ３ Since MgO is stable, when these nanoparticles are used as a template, the thermal reduction does not proceed, and the nanoparticles also coexist in the fired body. Therefore, in the washing step 108, it is necessary to dissolve and wash the template using an acid or alkali. In this way, the material from which the template has been removed is neutralized, washed with water, and dried to obtain a porous carbon material 109.

[0061] Thereafter, depending on the application, graphitization may be further promoted by further calcination at a high temperature. As for the calcination conditions, for example, the calcination may be carried out under an inert gas atmosphere at a calcination temperature of 1200 to 2200°C, preferably 1400 to 2000°C. The calcination time may be 1 to 10 hours, preferably 3 to 6 hours. There are no particular restrictions on the temperature rise rate, but a rate of 1 to 50°C / min is acceptable, although a rate of 20 to 50°C / min is preferred from the viewpoint of productivity.

[0062] According to the method for producing a porous carbon material according to the embodiment, a precursor material 105 consisting of a nitrogen-containing biomass material 102, metal oxide nanoparticles 103, and a dispersion medium 101 is frozen and fired to form a porous carbon material having a specific surface area of ​​500 to 3000 m. ２ / g, a pore diameter of 100 nm or less, and a nitrogen content of 1 to 15%. This makes it possible to safely and inexpensively produce a porous carbon material with a large specific surface area.

[0063] Examples Embodiments of the present disclosure will be described based on examples. However, the embodiments are not limited to the following examples. Dispersion medium: water (ultrapure water) Carbon source: gelatin (Fujifilm Wako Pure Chemical Industries), chitin (Fujifilm Wako Pure Chemical Industries) Template: ZnO (Fujifilm Wako Pure Chemical Industries, 0.02 μm) Example 1 A porous carbon material was produced under the following conditions.

[0064] 5 g of water and 0.5 g of gelatin were placed in a 50 ml beaker and immersed for 10 minutes. 5 g of water heated to 60°C was added thereto and stirred with a stirrer to obtain a mixed solution. The weight ratio of gelatin, ZnO nanoparticles, and ultrapure water was 1:1:20. This precursor raw material was placed in a freezer and frozen at -20°C for one day. Thereafter, the frozen precursor was placed in an alumina boat-shaped crucible and heated under a nitrogen atmosphere (N ２ Purity: 99.99%, N ２ The mixture was heated to 950°C at a flow rate of 70 ml / min and a temperature increase rate of 10°C / min, and then maintained at this temperature for 2 hours for calcination. A porous carbon material was obtained with a yield of 10.2%. The specific surface area S of the porous carbon material ＢＥＴ Measurement of the specific surface area S of the porous carbon material ＢＥＴ Based on JIS Z 8830:2013, ２ The specific surface area of ​​the fired body was determined by gas adsorption measurement. ＢＥＴ is 625m ２ The total pore volume V of the porous carbon material was relatively large at 1 / g. Ｔ , and mesopore volume V ｍｅｓｏ Measurement of the total pore volume V of the porous carbon material Ｔ , and mesopore volume V ｍｅｓｏ is based on JIS Z 8831-2:2010, ２ It can be determined by analyzing the adsorption or desorption side of the adsorption isotherm obtained by gas adsorption measurement. ｍｅｓｏ / V Ｔ [%] is calculated from these results. Measurement of nitrogen content of porous carbon material The nitrogen content of the porous carbon material was determined by measurement and analysis using X-ray photoelectron spectroscopy (XPS), and it was found that 1.44% of nitrogen atoms were doped. Measurement of biomass degree of porous carbon material by accelerator mass spectrometry (AMS) The sample was burned, and the generated carbon dioxide was reduced with hydrogen using an iron catalyst to produce graphite. This graphite was packed into a cathode with an inner diameter of 1 mm using a hand press, which was then fitted into a wheel and attached to an AMS measurement device. A tandem accelerator-based １４ Using a dedicated C-AMS device (NEC), １４ Counting C, １３ C concentration ( １３ C / １２ C), １４ C concentration ( １４ C / １２ C) was measured. At this time, oxalic acid was used as a standard sample. The measured values ​​were corrected according to ASTM D6866-22, and the biomass degree was calculated using the pMC. The biomass degree was calculated as follows: １４ of oxalic acid, a standard sample containing C １４ C concentration ( １４ C / １２ C) of the sample １４ C concentration ( １４ C / １２ C) is expressed as a ratio of the amount of the sample. １４ C concentration ( １４ C / １２ C) / Standard sample １４ C concentration ( １４ C / １２ The biomass degree is expressed only as a numerical value excluding the unit of % by the formula {C)}×100. The biomass degree of the porous carbon material according to Example 1 was 100 pMC.

[0065] For comparison, the biomass degrees of artificial graphite (Panasonic, PGF), gelatin (Fujifilm Wako Pure Chemical Industries), and chitin (Fujifilm Wako Pure Chemical Industries) were also measured. As a result of the measurements, the biomass degree of the petroleum-derived artificial graphite was 0 pMC, while the biomass degrees of gelatin and chitin were 100 pMC.

[0066] Example 2 A porous carbon material was produced using the same procedures and conditions as in Example 1, except that the precursor raw material was treated in a foaming machine for 5 minutes before being placed in a freezer. A porous carbon material was obtained with a yield of 7.3%.

[0067] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1087m ２ / g. The nitrogen content was 1.44%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0068] Example 3 A conductive porous material was produced using the same procedures and conditions as in Example 2, except that the number of days of freezing in the freezer was changed from 1 to 7. A porous carbon material was obtained with a yield of 9.7%.

[0069] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1014m ２ The nitrogen content was 4.75%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0070] Example 4 A porous carbon material was produced using the same procedures and conditions as in Example 3, except that the blending ratio (by weight) of gelatin, ZnO nanoparticles, and water was changed from 1:1:20 to 1:1:30. The porous carbon material was obtained with a yield of 9.5%.

[0071] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1,374 m ２ The nitrogen content was 3.91%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0072] Example 5 A porous carbon material was produced using the same procedures and conditions as in Example 2, except that the blending ratio (by weight) of gelatin, ZnO nanoparticles, and water was changed from 1:1:20 to 1:0.3:10. The porous carbon material was obtained at a yield of 11.9%.

[0073] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 567m ２ The nitrogen content was 2.71%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0074] Example 6 A porous carbon material was produced using the same procedures and conditions as in Example 5, except that the blending ratio (by weight) of gelatin, ZnO nanoparticles, and water was changed from 1:0.3:10 to 1:0.7:10. The porous carbon material was obtained at a yield of 9.3%.

[0075] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 914m ２ The nitrogen content was 5.15%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0076] Example 7 A precursor material was prepared with a blending ratio (by weight) of gelatin, ZnO nanoparticles, and water of 1:0.5:10. This was treated in a foaming machine for 5 minutes, and then rapidly cooled with liquid nitrogen and frozen for 0.01 hours. The frozen precursor was then placed in an alumina boat-shaped crucible and heated under a nitrogen atmosphere (N ２ Purity: 99.99%, N ２ The mixture was heated to 1000°C at a flow rate of 70 ml / min and a temperature increase rate of 10°C / min, and then maintained at this temperature for 2 hours for calcination. A porous carbon material was obtained in a yield of 8.7%.

[0077] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 983m ２ The nitrogen content was 2.34%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0078] Example 8 A porous carbon material was produced using the same procedures and conditions as in Example 7, except that the blending ratio (by weight) of gelatin, ZnO nanoparticles, and water was changed from 1:0.5:10 to 1:1:10. The porous carbon material was obtained at a yield of 5.8%.

[0079] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1531m ２The nitrogen content was 2.40%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0080] Example 9 A porous carbon material was produced using the same procedures and conditions as in Example 8, except that the blending ratio (by weight) of gelatin, ZnO nanoparticles, and water was changed from 1:1:10 to 1:1:8. The porous carbon material was obtained at a yield of 7.0%.

[0081] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1515m ２ The nitrogen content was 2.68%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0082] Example 10 A precursor material was prepared by mixing chitin and ZnO nanoparticles at a blending ratio (by weight) of 1:1. This precursor material was placed in an alumina boat-shaped crucible and heated under a nitrogen atmosphere (N ２ Purity: 99.99%, N ２ The mixture was heated to 950°C at a flow rate of 70 ml / min and a temperature increase rate of 5°C / min, and then maintained at that temperature for 6 hours for calcination. A porous carbon material was obtained with a yield of 9.7%. The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. The specific surface area S ＢＥＴ is 1710m ２ The nitrogen content was 1.53%. The biomass degree of the porous carbon material was 100 pMC because chitin was used as the raw material.

[0083] Example 11 In the (1) step of preparing the precursor material 105 in the first embodiment, a portion of the metal oxide nanoparticles 103 having a number average particle size of 100 nm or less can be replaced with metal compound particles 110 ( FIG. 1B ). ２ particles were used.

[0084] Gelatin, ZnO nanoparticles, and ZnCl ２ The mixing ratio (by weight) of ZnO and water was 1:1 (ZnO:ZnCl２ = 1:0.1): 10, and firing was carried out under a nitrogen atmosphere (N ２ Purity: 99.99%, N ２ The mixture was heated to 600°C at a flow rate of 70 ml / min and a temperature increase rate of 10°C / min, held for 3 hours, and then heated to 950°C, and held for 2 hours for calcination. Except for this, a porous carbon material was produced using the same procedure and conditions as in Example 8. The porous carbon material was obtained in a yield of 12.8%.

[0085] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1,198 m ２ / g. The nitrogen content was 1.11%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0086] Example 12: ZnO nanoparticles and ZnCl ２ The compounding ratio of ZnO:ZnCl ２ A porous carbon material was produced using the same procedures and conditions as in Example 11, except that the ratio of hydroxybenzoate to hydroxybenzoate was changed to 1:0.3. The porous carbon material was obtained in a yield of 15.3%.

[0087] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1,151 m ２ The nitrogen content was 1.43%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0088] Comparative Example 1 A porous carbon material was produced using the same procedures and conditions as in Example 2, except that the freezing time of the precursor raw material in the freezer was changed to 0 hours. A porous carbon material was obtained with a yield of 7.8%.

[0089] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. The specific surface area of ​​the carbon material was 405 m ２The nitrogen content was 0.41%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0090] Comparative Example 2 A porous carbon material was produced using the same procedures and conditions as in Example 1, except that the blending ratio (by weight) of gelatin, ZnO nanoparticles, and water was changed from 1:1:20 to 1:0.3:0 (no water). The carbon material was obtained at a yield of 14.7%.

[0091] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. The specific surface area of ​​the porous carbon material was 148 m ２ The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0092] Comparative Example 3: ZnO nanoparticles and ZnCl ２ The compounding ratio of ZnO:ZnCl ２ A porous carbon material was produced using the same procedures and conditions as in Example 11, except that the ratio of hydroxybenzoate to hydroxybenzoate was changed to 1:0.5. The porous carbon material was obtained in a yield of 17.5%.

[0093] The specific surface area, nitrogen content, and biomass ratio of the porous carbon material were measured in the same manner as in Example 1. ＢＥＴ is 1087m ２ The nitrogen content was 0.97%. The biomass degree of the porous carbon material was 100 pMC because gelatin was used as the raw material.

[0094] 3 is Table 1 showing the raw materials, production conditions, and evaluation results of Examples 1 to 12 and Comparative Examples 1 to 3. The left arrow in the table has the same meaning as the left column.

[0095] According to one embodiment of the present disclosure, the porous carbon material has a specific surface area of ​​500 to 3000 m ２ / g, pore diameter of 100 nm or less, nitrogen content of 1 to 15 atomic %, and the balance being carbon. When measured by accelerator mass spectrometry (AMS), １４ C concentration ( １４ C / １２C) Non-fossil fuel-derived standard sample １４ C concentration ( １４ C / １２ The biomass ratio, expressed as a ratio to the total mass of the porous carbon material (C), is in the range of 5 to 100 pMC. This makes it possible to provide a porous carbon material and an electricity storage / power generation device including the same.

[0096] Furthermore, according to the method for producing a porous carbon material according to one aspect of the present disclosure, it is possible to provide a method for producing the porous carbon material inexpensively and easily.

[0097] According to the method for producing a porous carbon material according to one embodiment of the present disclosure, a nitrogen-containing porous carbon material with a large specific surface area, which has previously been difficult to obtain quickly and inexpensively, can be easily obtained by an environmentally friendly process using a nitrogen-containing biomass raw material and metal oxide nanoparticles. Therefore, the present disclosure has high industrial applicability.

[0098] A porous carbon material according to one embodiment of the present disclosure can be used in a wide range of applications, for example, as an electrode material for electricity storage devices such as lithium ion secondary batteries and electric double layer capacitors, and power generation devices such as fuel cells and solar cells.

[0099] 101 Dispersion medium 102 Nitrogen-containing biomass raw material 103 Metal oxide nanoparticles 104 Mixing, foaming, and dispersion process 105 Precursor raw material 106 Freezing process 107 Firing process 108 Washing process 109 Porous carbon material 110 Metal compound particles

Claims

1. A sintered body having a specific surface area of ​​500 to 3000 m ２ / g, the pore size of the sintered body is 100 nm or less, the nitrogen content of the sintered body is 1 to 15 atomic %, and the remainder of the sintered body is carbon, the biomass degree of the sintered body is in the range of 5 to 100 pMC, and the biomass degree of the sintered body is measured by accelerator mass spectrometry (AMS method). １４ C concentration ( １４ C / １２ C) Standard samples not derived from fossil fuels １４ C concentration ( １４ C / １２ C) the porous carbon material.

2. The porous carbon material according to claim 1, wherein the pore diameter includes micropores having a diameter of 2 nm or less and mesopores having a diameter of 2 nm or more and 50 nm or less.

3. The porous carbon material according to claim 2, wherein the pores further include macropores having a diameter of 100 nm or more.

4. An electrode comprising the porous carbon material according to any one of claims 1 to 3.

5. A device for storing or generating electricity, comprising the electrode according to claim 4.

6. A method for producing a porous carbon material, comprising: (1) a step of preparing a precursor raw material by mixing, foaming, and dispersing a dispersion medium, a nitrogen-containing biomass raw material, and metal oxide nanoparticles serving as a template having a number average particle size of 100 nm or less; (2) a step of calcining the precursor raw material and graphitizing it to obtain a calcined body; and (3) a step of removing the metal oxide nanoparticles from the calcined body to obtain a porous carbon material.

7. The method for producing a porous carbon material according to claim 6, wherein the metal oxide nanoparticles serving as the template are ZnO particles.

8. The method for producing a porous carbon material according to claim 6, wherein the nitrogen-containing biomass raw material is at least one selected from the group consisting of natural sugars, proteins, and nucleic acids.

9. The method for producing a porous carbon material described in claim 6, wherein the nitrogen-containing biomass raw material is at least one selected from the group consisting of gelatin, chitin, chitosan, glucosamine, deoxyribonucleic acid (DNA), and ribonucleic acid (RNA).

10. The biomass degree of the nitrogen-containing biomass raw material is in the range of 5 to 100 pMC, and the biomass degree of the nitrogen-containing biomass raw material is measured by accelerator mass spectrometry (AMS method). １４ C concentration ( １４ C / １２ C) Standard samples not derived from fossil fuels １４ C concentration ( １４ C / １２ The method for producing a porous carbon material according to claim 6, wherein the ratio is expressed to C).

11. The method for producing a porous carbon material according to claim 6, wherein metal compound particles other than an oxide are added as the precursor raw material.

12. The metal compound particles are ZnCl ２ The method for producing a porous carbon material according to claim 11 , wherein the porous carbon material is in the form of particles.