Method for Preparing Amine-containing Bacterial Cellulose from Nitrogen-containing Carbon Source

Abstract

The present disclosure describes a method for producing bacterial cellulose in which nitrogen atoms (e.g., amine groups) are introduced into the cellulose structure by performing microbial culture in the presence of a specific nitrogen atom-containing carbon source, and uses thereof.

Description

Technology Field

[0001] The present disclosure relates to a method for producing amine group-containing bacterial cellulose from a nitrogen atom-containing carbon source. More specifically, the present disclosure relates to a method for producing bacterial cellulose in which a nitrogen atom (e.g., an amine group) is introduced into the cellulose structure by performing microbial culture in the presence of a specific nitrogen atom-containing carbon source, and to uses thereof. Background Technology

[0002] Bacterial cellulose (BC) is a natural polymer produced through the metabolic processes of microorganisms. Due to its characteristics such as high crystallinity, excellent mechanical strength, high water retention, and biocompatibility, it is a material with high potential for application in various fields, including medical materials, food additives, cosmetics, and electronic materials.

[0003] Recently, carbon materials made by carbonizing bacterial cellulose have been attracting attention as electrode materials for energy storage devices, such as supercapacitors. These bacterial cellulose-based carbon materials are known to have the potential to be electrode materials with high energy density and power density due to their high surface area, excellent electrical conductivity, and efficient ion transport characteristics resulting from their three-dimensional network structure.

[0004] However, pure bacterial cellulose-based carbon materials have limited charge storage performance due to a lack of electrochemically active sites. To address this, research is actively being conducted to improve the electrochemical properties of electrode materials by doping them with heteroatoms such as nitrogen (N), sulfur (S), and phosphorus (P) (e.g., Cellulose (2024) 31:7793-7817 et al.). In particular, nitrogen doping is known to increase electrical conductivity through electron donating effects, and to improve charge storage capacity through the contribution of nitrogen functional groups to pseudocapacitance.

[0005] Conventional nitrogen doping methods primarily involve introducing nitrogen functional groups through chemical post-treatment processes such as silanization, in-situ polymerization, or oxidation after producing BC, or performing high-temperature treatment using ammonia or nitrogen gas during the carbonization process.

[0006] However, the aforementioned conventional technology has the following problems.

[0007] First, the chemical post-treatment process is complex and requires high temperature and high pressure conditions, resulting in high energy consumption and increased process costs.

[0008] Second, reproducibility is reduced because the degree and uniformity of doping are inconsistent depending on changes in conditions such as the concentration of chemicals used for doping, reaction time, and temperature.

[0009] Third, the environmental burden is significant because hazardous chemicals are used or by-products are generated during the post-processing stage.

[0010] Fourth, since nitrogen doping is limited only to the surface of BC, its performance as an electrode material is limited.

[0011] As such, there is a need for a method to produce bacterial cellulose with a simplified process, excellent reproducibility, and environmental friendliness, while also having uniformly introduced nitrogen. The problem to be solved

[0012] In one embodiment of the present disclosure, the technical limitations of the prior art are overcome, and a method for introducing nitrogen atoms into bacterial cellulose without a separate nitrogen doping process is provided.

[0013] In another embodiment of the present disclosure, a method is provided for producing bacterial cellulose with introduced nitrogen atoms with high repeatability.

[0014] In another embodiment of the present disclosure, a method is provided for applying bacterial cellulose with introduced nitrogen atoms to various fields. means of solving the problem

[0015] According to one embodiment of the present disclosure,

[0016] a) adding a carbon source comprising an amine-based compound having at least one hydroxyl group to a microbial culture medium, and performing culture by a bacterial cellulose-producing strain;

[0017] A method for producing bacterial cellulose comprising,

[0018] The above bacterial cellulose is a form in which amine groups are introduced into the cellulose structure, and

[0019] A method of manufacturing is provided in which the nitrogen content in the bacterial cellulose is in the range of 0.4 to 1 weight% on an elemental basis.

[0020] According to an exemplary embodiment, the bacterial cellulose-producing strain may be at least one selected from the group consisting of the genus Acetobacter, the genus Gluconacetobacter, the genus Agrobacterium, the genus Rhizobium, the genus Sarcina, the genus Pseudomonas, the genus Achromobacter, the genus Alcaligenes, and the genus Aerobacter.

[0021] According to exemplary embodiments, the carbon source may be a single carbon source of an amine-based compound having at least one hydroxyl group, or a combination of an amine-based compound having at least one hydroxyl group and other carbon-containing compounds.

[0022] According to an exemplary embodiment, when the carbon source is a single carbon source of an amine-based compound having at least one hydroxyl group, the concentration of the amine-based compound having at least one hydroxyl group in the culture medium can be controlled in the range of 0.1 to 100 g / L.

[0023] According to an exemplary embodiment, when the carbon source is a combination of an amine-based compound having at least one hydroxyl group and other carbon-containing compounds, the concentration of each of the amine-based compound having at least one hydroxyl group and other carbon-containing compounds in the culture medium can be controlled in the ranges of 0.1 to 4.5 g / L and 5 to 100 g / L.

[0024] According to an exemplary embodiment, the other carbon-containing compound as a carbon source may be at least one selected from the group consisting of glucose, sucrose, maltose, fructose, mannose, mannitol, sorbitol, erythritol, invert sugar, cellobiose, and glycerol.

[0025] According to an exemplary embodiment, the microbial culture medium may be selected from the group consisting of Hestrin-Schramm (HS) medium, Yamanaka medium, Modified synthetic medium (MSM), and ZM1 medium.

[0026] According to an exemplary embodiment, in step a), the pH of the microbial culture medium can be adjusted to a range of 4 to 7.

[0027] According to an exemplary embodiment, in step a), the culture can be performed at 10 to 50°C for 5 to 20 days.

[0028] According to an exemplary embodiment, the amine-based compound having at least one hydroxyl group may be an aminoalkanediol having 2 to 6 carbon atoms.

[0029] According to an exemplary embodiment, the amine-based compound having at least one hydroxyl group may be serinol.

[0030] According to an exemplary embodiment,

[0031] A step of carbonizing the bacterial cellulose prepared above through at least one heat treatment;

[0032] A method for manufacturing a nitrogen-doped carbon material comprising is provided.

[0033] According to an exemplary embodiment, the heat treatment includes a first heat treatment step and a second heat treatment step, and

[0034] At this time, the first heat treatment step is performed under an oxygen-containing atmosphere at a controlled temperature in the range of 150 to 300 ℃, and

[0035] The second heat treatment step can be performed under an inert gas atmosphere at a controlled temperature in the range of 500 to 2000 ℃.

[0036] According to an exemplary embodiment, the first heat treatment and the second heat treatment may be performed for 0.5 to 5 hours and 0.5 to 5 hours, respectively.

[0037] According to an exemplary embodiment, the nitrogen content (doping amount) in the nitrogen-doped carbon material may be controlled in the range of 2 to 5 weight percent on an elemental basis.

[0038] According to an exemplary embodiment, the nitrogen-doped carbon material may contain all of the bonded states of pyridine-type nitrogen, pyrrole-type nitrogen, and graphite-type nitrogen upon XPS analysis.

[0039] According to an exemplary embodiment, the content of each of the pyridine-type nitrogen, pyrrole-type nitrogen, and graphite-type nitrogen in the nitrogen-doped carbon material may be in the range of 0.2 to 1 weight%, 1 to 1.8 weight%, and 0.5 to 1.5 weight%.

[0040] According to an exemplary embodiment, an electrode material for an electrochemical device comprising the nitrogen-doped carbon material is provided.

[0041] According to an exemplary embodiment, the electrochemical device may be a supercapacitor. Effects of the invention

[0042] According to a specific embodiment of the present disclosure, by adopting an in-situ nitrogen doping method in which nitrogen is directly introduced into the cellulose structure during the microbial culture stage without complex chemical post-treatment processes, the bacterial cellulose manufacturing process can be simplified, and energy consumption and production costs can be reduced. Furthermore, as this is an eco-friendly process utilizing microbial metabolism, the use of hazardous chemicals is minimized and the generation of by-products is low, making it environmentally friendly. In addition, the level of nitrogen introduction into the cellulose can be controlled by adjusting the concentration of a nitrogen-containing carbon source, thereby enabling the reproducible production of bacterial cellulose with desired characteristics. The nitrogen-doped bacterial cellulose produced in this manner can be utilized in various fields, such as energy storage materials, biopolymers, and medical materials. In particular, according to the present embodiment, a carbon material derived from bacterial cellulose with uniformly dispersed nitrogen has excellent electrical conductivity, texture (specific surface area, etc.), and electrochemical activity, and provides the advantage of being suitable for use as a material for electrochemical devices such as supercapacitors (e.g., electrode material), and can achieve properties (e.g., high capacitance and low internal resistance). Brief explanation of the drawing

[0043] FIG. 1 is a scanning electron microscope image (magnification: 10,000x) showing the surface morphology and structure of bacterial cellulose (bacterial nanocellulose) prepared in the example; FIG. 2 is a graph showing the production of bacterial cellulose according to various serinol concentrations in the example; FIG. 3 is the FTIR spectrum of the control group and samples S1 to S4; FIGS. 4a to 4e are each high-resolution XPS spectra (C 1s, O 1s, and N 1s) for the control sample (BNC) and samples S1 to S4, respectively; Figures 5a and 5b are graphs showing the nitrogen adsorption-desorption isotherms and BJH analysis results for serinol-modified carbon samples cS2 and cS3 obtained by carbonizing samples S2 and S3; FIG. 6 is the high-resolution XPS spectrum (C 1s, O 1s and N 1s) of the serinol-modified carbon sample cS3 obtained by carbonizing the S3 sample; and FIG. 7 shows (a) CV curve at 5 mV, (b) GCD curve at 1 A / g, and (c) Nyquist plot for each of the serinol-modified carbon samples cS1 to cS3 obtained by carbonizing the carbonized BNC (cBNC) sample (control) and the samples S1 to S3, respectively. Specific details for implementing the invention

[0044] The present invention can be fully achieved by the following description. The following description should be understood as describing preferred embodiments of the present invention, but the present invention is not necessarily limited thereto. Furthermore, the attached drawings are for illustrative purposes only and do not limit the present invention; details regarding individual components can be appropriately understood in accordance with the specific intent of the relevant descriptions provided below.

[0045] Terms used in this specification may be defined as follows.

[0046] "Cellulose" can refer to an organic compound in which glucose units are linearly linked through β-1,4 glycosidic bonds.

[0047] "Bacterial cellulose" may refer to cellulose produced by the biosynthesis of microorganisms, such as acetic acid bacteria belonging to Acetobacter, Pseudomonas, and Rhizobium. Typically, when acetic acid bacteria are inoculated into a liquid medium containing nutrients such as carbon sources and nitrogen sources and subjected to static culture, a hydrogel-like film having a three-dimensional network structure is formed at the interface between the medium and the gas phase, which can be referred to as "bacterial cellulose."

[0048] "Carbon source" can be understood to mean an organic compound that is consumed by microorganisms and used as an energy source (ATP production) for maintaining life and cell proliferation, while simultaneously functioning as a precursor for forming glucose units, which are the basic units that make up cellulose chains.

[0049] "Medium" or "culture medium" may refer to a mixture in a liquid or solid state that provides all the nutrients and environmental factors necessary for microorganisms or strains (e.g., bacterial cellulose-producing strains) to grow and multiply while simultaneously biosynthesizing cellulose nanofibers.

[0050] The expression “nitrogen atoms are introduced (inserted) into the cellulose structure” may refer to a form in which amine groups, ammonium groups, and related functional groups containing nitrogen (N) atoms are chemically bonded or physically firmly integrated within the network of cellulose produced by microorganisms or its fibrils. This is conceptually distinct from a form in which amine compounds are attached to the surface of cellulose (e.g., physically adsorbed), and can be understood as meaning a state in which CN bonds and / or protonated amine peaks are detectable during spectroscopic analysis (e.g., XPS).

[0051] In a broad sense, "carbonization" can be understood as a process of heating organic materials to high temperatures under oxygen-free or oxygen-lean conditions to remove volatile components within the organic materials and induce bonding between carbon atoms to form a carbon network structure; in a narrow sense, it can be understood as a thermochemical process of thermally decomposing bacterial cellulose, an organic material, to remove non-carbon components (hydrogen, oxygen, etc.) and converting it into a conductive carbon structure with a high carbon content.

[0052] Where a numeric range is specified in this specification as a lower limit and / or an upper limit, it may be understood that any sub-combination within said numeric range is also disclosed. For example, where "1 to 5" is written, it may include 1, 2, 3, 4 and 5, as well as any sub-combination between them.

[0053] When a component is said to "include," it means that, unless otherwise noted, it may include additional components.

[0054] In the case of the term "contact," in a narrow sense it means direct contact between two objects, but in a broad sense it can be understood as allowing any additional component to be involved.

[0055] The expressions "on" and "above" are used to refer to concepts of relative position, where not only are other components or layers directly present on the mentioned layer, but other layers (intermediate layers) or components may be interposed or present between them. Similarly, the expressions "below," "in the lower part," and "below," as well as the expression "between," can also be understood as concepts relative to position.

[0056] Overall opening content

[0057] According to one embodiment of the present disclosure, a method for producing nitrogen-containing bacterial cellulose is provided by performing microbial culture in the presence of a specific nitrogen atom-containing compound as a carbon source, specifically an amine-based compound having at least one hydroxyl group.

[0058] A notable feature of the method according to the present embodiment is that nitrogen atoms (functional groups, such as amine groups) are introduced in-situ into the cellulose structure during the synthesis of bacterial cellulose through microbial culture. This is distinct from adding amino acids, such as peptone and yeast extract, as nutrients to a general culture medium. Specifically, when amino acids are used as nutrients in a general culture medium, even if the amino acids contain nitrogen, the synthesized bacterial cellulose has a pure cellulose structure and has almost no nitrogen content or is merely at the level of impurities.

[0059] A method for producing nitrogen-doped bacterial cellulose will be described in detail below.

[0060] Synthesis of nitrogen-doped bacterial cellulose

[0061] - Carbon source

[0062] According to the present embodiment, a specific amine compound is used as a carbon source to introduce a nitrogen-containing functional group into the cellulose structure formed during microbial culture. Specifically, the amine compound as a carbon source may be an amine compound having at least one (specifically multiple) hydroxyl groups. According to an exemplary embodiment, the amine compound may be an amino alcohol, specifically an aminoalkanol, and more specifically an aminoalkanediol having two hydroxyl groups. In this case, the number of carbon atoms of the aminoalkanol or aminoalkanediol may be, for example, about 2 to 6, specifically about 3 to 5. In a specific embodiment, the amine compound may be serinol represented by the following chemical formula 1.

[0063] [Chemical Formula 1]

[0064]

[0065] Unlike general carbon sources (e.g., glycerol, etc.) which primarily provide a carbon skeleton, the aforementioned amine compounds provide nitrogen atoms along with the carbon skeleton, and act to directly introduce amine groups into the cellulose structure during the culture stage without the need for separate nitrogen doping.

[0066] Although the present disclosure is not bound by any specific theory, it is determined that the reason certain amine compounds are introduced (inserted) into the cellulose structure of bacterial cellulose synthesized during the microbial culture process is that certain amine compounds present in the culture medium are introduced by binding to the interior of the cellulose during the culture process and the process of cellulose production, or because they form a structure similar to a carbon source and can be utilized as a carbon source for bacteria (since the aforementioned amine compounds are similar in structure to a general carbon source, amine groups may be introduced during the process of producing cellulose as bacteria recognize and consume them as a carbon source).

[0067] When the aforementioned amine-based compound (e.g., serinol) is applied as a carbon source alone or in combination with another carbon source (e.g., glycerol), the hydroxyl groups (-OH) and amine groups (-NH2) contained therein form strong hydrogen bonds with glucose chains during the cellulose synthesis process, facilitating penetration and integration into the crystal lattice. Therefore, while functioning as a carbon source (or auxiliary carbon source), it can also act as a dopant that imparts nitrogen functional groups to the cellulose in the final product.

[0068] According to exemplary embodiments, a carbon-containing compound different from the one described above (another carbon-containing compound) may be used in combination with an amine-based compound having at least one hydroxyl group as a carbon source. Such other carbon-containing compounds may be of the type conventionally used in bacterial cellulose synthesis, such as glucose, sucrose, maltose, fructose, mannose, mannitol, sorbitol, erythritol, invert sugar, cellobiose, glycerol, etc. Such carbon sources may be extracts derived from plants or animals (e.g., yeast extract, etc.), or by-products generated during the synthesis or manufacture of polymers, fibers, plastics, biodiesel, dyes, etc. Typical examples of the aforementioned extracts or by-products may include, but are not limited to, crude glycerol and soybean hydrolysate extracts.

[0069] According to a specific embodiment, the aforementioned amine-based compound having at least one hydroxyl group may be used as an auxiliary carbon source, and other carbon-containing compounds may be used in combination as the main carbon source. In this case, the weight ratio of the amine-based compound to other carbon-containing compounds may be controlled in the range of, for example, 1: about 2 to 30, specifically 1: about 5 to 25, more specifically 1: about 8 to 15.

[0070] .

[0071] - Microorganisms (strains)

[0072] According to the present embodiment, the microorganism is not particularly limited as long as it can synthesize bacterial cellulose during the culture process. However, according to the exemplary embodiment, the microorganism may be exemplified by the genera Acetobacter, Gluconacetobacter, Agrobacterium, Rhizobium, Sarcina, Pseudomonas, Achromobacter, Alcaligenes, Aerobacter, etc., and at least one of the types listed above may be used. According to a specific embodiment, the microorganism Komagataeibacter sucrofermentans, Komagataeibacter xylinus, Komagataeibacter hansenii, Komagataeibacter rhaeticus You can use the back.

[0073] - Culture medium

[0074] According to an exemplary embodiment, the culture medium contains appropriate nutrients (such as the carbon source described above) necessary for the growth and proliferation of microorganisms or strains, and may additionally contain components, such as for controlling osmotic pressure and / or hydrogen ion concentration to make it suitable for culture if necessary.

[0075] In exemplary embodiments, examples of components added to the culture medium in addition to the carbon source may include pH regulators, antifoaming agents, various nitrogen sources such as amino acids (e.g., peptone, etc.), inorganic salts or inorganic ion sources (e.g., sodium, potassium, calcium, magnesium, iron, zinc, manganese, copper, etc.), various vitamins, buffers (e.g., phosphate buffer), etc.

[0076] As an example, inorganic salts or inorganic ion sources may be NaHPO4, MgSO4, KCl, KH2PO4, CaCl2, CaCO3, FeSO4, ZnSO4, MnSO4, CuSO4, etc. In addition, examples of vitamins may be riboflavin, p-aminobenzoic acid, folic acid, biotin, etc. Furthermore, the pH of the medium may be adjusted to an appropriate range to promote microbial growth, whereby the pH may be, for example, about 4 to 7, specifically about 4.5 to 6.5, more specifically about 5 to 6. To this end, alkali and / or acid may be used as pH adjusting components; examples of alkali components may be sodium hydroxide, potassium hydroxide, sodium carbonate, etc., and acid components may be acetic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid, etc. The aforementioned additive components should be understood as exemplary, and other components suitable for microbial culture may be further included or replaced.

[0077] According to exemplary embodiments, examples of the aforementioned media may include Hestrin-Schramm (HS) media, Yamanaka media, Modified synthetic medium (MSM), ZM1 media, etc. Specifically, Hestrin-Schramm (HS) media may be used.

[0078] - Microbial culture

[0079] According to exemplary embodiments, any microbial culture method known in the art may be applied for culturing microorganisms (colonies) for bacterial cellulose synthesis. As an example, the aforementioned carbon source may be added or dropped onto a medium containing a bacterial cellulose-producing strain and appropriate nutrients for cultivation. In this case, as a culture method, repetitive, semi-continuous, or continuous culture methods known in the art, such as static culture, shaking culture, and fed-batch, may be selectively applied. If necessary, high-productivity culture methods utilizing immobilized culture or airlift fermenters may also be used. Such culture methods may be appropriately selected or combined depending on the growth characteristics of the strain, medium composition, oxygen requirements, and production purpose.

[0080] According to an exemplary embodiment, when an amine-based compound having at least one hydroxyl group is used as a carbon source, the concentration in the medium can be controlled, for example, in the range of about 0.1 to 100 g / L, specifically about 1 to 50 g / L, more specifically about 2 to 20 g / L, but is not limited thereto as it can vary depending on the type of microorganism (bacteria), etc.

[0081] Meanwhile, according to another exemplary embodiment, when an amine-based compound having at least one hydroxyl group as a carbon source is used in combination with other carbon-containing compounds, the concentration of each of the amine-based compound and other carbon-containing compounds in the medium can be controlled, for example, in the range of about 0.1 to 4.5 g / L (specifically about 0.5 to 3.5 g / L, more specifically 1.2 to 2 g / L), and about 5 to 100 g / L (specifically about 10 to 50 g / L, more specifically about 20 to 30 g / L), but this should be understood as exemplary.

[0082] In addition, culture can be performed under stirring conditions, whereby the stirring speed is not specifically limited but can be controlled, for example, in the range of about 20 to 250 rpm, specifically about 40 to 220 rpm, more specifically about 100 to 200 rpm.

[0083] In addition, the culture temperature can be controlled, for example, in the range of about 10 to 50 ℃, specifically about 20 to 40 ℃, and more specifically about 25 to 35 ℃. Furthermore, although the culture time is not particularly limited, it may be in the range of about 5 to 20 days, specifically about 6 to 15 days, and more specifically about 8 to 12 days, but this should be understood as being for illustrative purposes.

[0084] Once culture is complete, post-processing and / or separation and purification steps known in the art may be performed as needed. For example, to remove cells, proteins, etc. contained in the medium, the culture may be immersed in an alkaline solution (e.g., sodium hydroxide solution), heat treated, and additionally washed with water at least once and then dried to obtain nitrogen-doped bacterial cellulose.

[0085] As mentioned above, as bacterial cellulose is formed during the culture process, nitrogen derived from amine compounds is introduced into the cellulose structure. At this time, it should be noted that amino acids used as nutrients in the medium (such as peptone and yeast extract) are consumed solely as nitrogen sources and nutrients for the growth of microorganisms or strains, and unlike amine compounds, they do not modify the chemical structure of cellulose or provide functional groups.

[0086] According to an exemplary embodiment, the synthesized bacterial cellulose is in a form in which amine groups are introduced into the cellulose structure. In this case, the nitrogen content in the bacterial cellulose may be in the range of, for example, about 0.4 to 1 weight%, specifically about 0.45 to 0.9 weight%, more specifically about 0.5 to 0.85 weight%, and particularly specifically about 0.6 to 0.8 weight% on an elemental basis.

[0087] In addition, when bacterial cellulose is analyzed by XPS (X-ray Photoelectron Spectroscopy), CN bonds and / or protonated amine peaks may be detected, which may indicate that nitrogen derived from amine compounds is bonded to the cellulose network.

[0088] Manufacturing of nitrogen-doped carbon materials

[0089] According to another embodiment of the present disclosure, a method for producing a carbon material (nitrogen-containing carbon material) using nitrogen-doped bacterial cellulose synthesized through microbial culture is provided. Specifically, the nitrogen-doped bacterial cellulose is heat-treated to perform carbonization treatment.

[0090] According to an exemplary embodiment, the heat treatment can be performed in at least one step, specifically through a first heat treatment and a second heat treatment.

[0091] - 1st heat treatment

[0092] In an exemplary embodiment, the first heat treatment is performed to thermally and structurally stabilize bacterial cellulose, which is a precursor of the carbon material, and can typically be performed under an oxygen-containing atmosphere. Specifically, in the first heat treatment step, dehydration and cross-linking of the cellulose chains are induced prior to high-temperature pyrolysis (carbonization) to strengthen the structural framework, thereby preventing structural collapse during the subsequent pyrolysis process and increasing the carbon yield.

[0093] For example, the oxygen-containing atmosphere may be formed by a gas containing oxygen, for example, at least about 50% (v / v), specifically at least about 70% (v / v), more specifically at least about 80% (v / v), and in some cases, pure oxygen. According to another embodiment, it may be in the form of a mixed gas with another diluent gas (e.g., nitrogen, etc.), for example, an air atmosphere.

[0094] In addition, the first heat treatment temperature can be determined by considering the temperature at which cellulose decomposes, for example, in the range of about 150 to 300 ℃, specifically about 200 to 280 ℃, and more specifically about 210 to 250 ℃. In addition, the heating rate to the first heat treatment temperature can be controlled by considering the decomposition stability of cellulose, for example, in the range of about 1 to 10 ℃ / min, specifically about 2 to 8 ℃ / min, and more specifically about 3 to 6 ℃ / min.

[0095] In addition, the first heat treatment time may be adjusted considering the stabilization state of the cellulose, for example, in the range of about 0.5 to 5 hours, specifically about 1 to 4 hours, more specifically about 2 to 3.5 hours, but this may be understood as being for illustrative purposes.

[0096] - 2nd heat treatment

[0097] According to an exemplary embodiment, the second heat treatment is a process of substantially carbonizing the carbon precursor stabilized through the first heat treatment (a structural rearrangement process that converts the nitrogen-doped precursor into a nitrogen-doped carbon material having electrochemical activity). Specifically, through the second heat treatment, non-carbon atoms (hydrogen, oxygen, etc.) are released in gaseous form, and the remaining carbon atoms are arranged in a form such as a hexagonal ring structure. In particular, in the present embodiment, nitrogen atoms derived from the amine-based compound previously introduced into bacterial cellulose can be converted into pyridinic, pyrroleic, and / or graphitic nitrogen and fixed within the carbon lattice (i.e., converted into a nitrogen-doped carbon material).

[0098] To this end, heat treatment may be performed at a temperature significantly higher than the first heat treatment condition, provided that, unlike in the first heat treatment, it may be performed under an inert atmosphere. Such an inert atmosphere may be formed by at least one gas selected from helium, neon, nitrogen, argon, etc., and specifically, it may be an argon gas atmosphere.

[0099] According to an exemplary embodiment, the second heat treatment temperature can be controlled in consideration of the yield or the structure and characteristics of the carbon produced, for example, in a range of about 500 to 2000 ℃, specifically about 600 to 1500 ℃, and more specifically about 700 to 1000 ℃. In addition, the heating rate to the second heat treatment temperature can be controlled in consideration of the starting temperature and the time required, for example, in a range of about 1 to 10 ℃ / min, specifically about 3 to 8 ℃ / min, and more specifically about 4 to 6 ℃ / min.

[0100] In addition, the second heat treatment time can be adjusted by taking into account the balance between the crystallinity of the carbon structure and the degree of nitrogen fixation, for example, in the range of about 0.5 to 5 hours, specifically about 1 to 4 hours, more specifically about 1.5 to 3 hours, but this can be understood as being for illustrative purposes.

[0101] After performing the carbonization process by the aforementioned heat treatment (or multi-stage heat treatment), post-treatment may be performed depending on the subsequent process or application. As an example, nitrogen-doped carbon can be obtained by performing an activation treatment with an alkaline solution (e.g., potassium hydroxide solution) and further performing post-treatment such as washing with water at least once to remove residual inorganic matter. For example, the obtained nitrogen-doped carbon may be in powder form, and its size (average diameter) may include, for example, nanofibers with a primary structure of about 10 to 100 nm, specifically about 20 to 80 nm. In addition, the nanofibers may aggregate to form porous aggregated particles with an average particle diameter of about 1 to 100 μm, specifically about 5 to 30 μm, as a secondary structure, but are not limited thereto.

[0102] In this regard, the nitrogen content (doping amount) in the obtained nitrogen-doped carbon can be controlled, on an elemental basis, in a range of, for example, about 2 to 5 weight%, specifically about 2.2 to 4 weight%, more specifically about 2.5 to 3.5 weight%.

[0103] In addition, nitrogen-doped carbon may have a porous structure, for example, the specific surface area (BET) may be in the range of, for example, at least about 300 to 1300 m² / g, specifically about 500 to 1100 m² / g, and more specifically about 700 to 1000 m² / g. Also, regarding the pore volume, for example, at least about 0.2 to 1 cm² 3 / g, specifically about 0.4 to 0.8 cm 3 / g, more specifically about 0.5 to 0.7 cm 3 It may be in the range of / g. In addition, the average pore diameter may be, for example, in the range of at least about 1.5 to 3 nm, specifically about 1.7 to 2.8 nm, more specifically about 2 to 2.5 nm.

[0104] Meanwhile, in terms of composition, the nitrogen-doped carbon material may contain all of the bonded states of pyridine-type nitrogen, pyrrole-type nitrogen, and graphite-type nitrogen when analyzed by XPS. As an example, the content of pyridine-type nitrogen in the nitrogen-doped carbon material may be, for example, in the range of about 0.2 to 1 wt%, specifically about 0.3 to 0.9 wt%, more specifically about 0.4 to 0.8 wt%. In addition, the content of pyrrole-type nitrogen may be, for example, in the range of about 1 to 1.8 wt%, specifically about 1.1 to 1.7 wt%, more specifically about 1.2 to 1.6 wt%. Furthermore, the content of graphite-type nitrogen may be, for example, in the range of about 0.5 to 1.5 wt%, specifically about 0.6 to 1.3 wt%, more specifically about 0.7 to 1.2 wt%.

[0105] The nitrogen-doped carbon material according to the present embodiment can exhibit excellent electrical conductivity due to the synergistic effect derived from the three-dimensional network structure of cellulose nanofibers and nitrogen introduced in situ. This is believed to be because nitrogen atoms act as electron donors when doped into the carbon lattice, thereby promoting charge transfer, and additional improvement in electrical conductivity can be achieved if conductive materials or conductive nanoparticles (e.g., CNT, graphene, etc.) are additionally introduced as needed.

[0106] For example, the specific capacitance of the nitrogen-doped carbon material may be in the range of, for example, at least about 300 F / g, specifically at least about 450 F / g, and more specifically about 480 to 700 F / g when measured under 1 A / g condition. In addition, the series resistance (Rs), indicated as charge transfer resistance, may be in the range of, for example, about 15 Ω or less, specifically about 12 Ω or less, and more specifically about 5 to 10 Ω when measured under 0.1 Hz condition, which can effectively improve rate capability when applied to electrochemical devices requiring high power characteristics. Furthermore, cycle stability during long-term charge and discharge can also be improved due to the improvement in structural stability caused by nitrogen doping.

[0107] Due to improved electrical conductivity, the nitrogen-doped carbon material according to the present embodiment can be applied as an electrode material for electrochemical devices, and in particular, when applied to a supercapacitor, the improvement effect can be further enhanced due to the improved ion storage capacity and rapid electron transport characteristics caused by specific nitrogen-bonded species.

[0108] The present invention can be more clearly understood by the following examples, which are merely for illustrative purposes and are not intended to limit the scope of the invention.

[0109] Examples

[0110] The analysis performed for characterization in this embodiment was carried out as follows.

[0111] Characterization analysis

[0112] a. Fourier Transform Infrared Spectroscopic Analysis (FTIR)

[0113] A Cary 630 FTIR (Agilent Technologies, USA) was used, and the procedure was performed with an ATR (Attenuated Total Reflectance) accessory. Measurements were taken by directly contacting dried BNC films with the ATR crystal without any separate pretreatment. The analysis wavelengths were 4,000 to 400 cm⁻¹. -1 Collected within the range.

[0114] B. X-ray Photoelectron Spectroscopy (XPS)

[0115] K-Alpha + The analysis was performed using an analyzer (Thermo Fisher Scientific, USA), and after acquiring a survey spectrum over the entire binding energy range (0-1400 eV), a high-resolution scan was performed on the C 1s, O 1s, and N 1s regions.

[0116] Peak deconvolution was performed using the Gaussian curve fitting method with OriginPro 2016 (OriginLab, USA), and only results with a coefficient of determination (R²) of 0.99 or higher were considered valid analyses.

[0117] C. Elemental Analysis

[0118] Elemental analysis was performed on approximately 5 mg of dried BNC samples using a CHNOS analyzer (FLSAH SMART, Thermo Fisher Scientific, USA).

[0119] Electrochemical performance analysis

[0120] - Cyclic Volammetry (CV) Analysis

[0121] Measurements were taken under conditions of a potential range of 0 to -1 V (vs. Ag / AgCl) and a scan rate of 5 mV / s.

[0122] - Galvanostatic Charge / Discharge (GCD) Analysis

[0123] It was performed under a current density of 1 A / g, and the capacitance was calculated based on the discharge section of the GCD curve.

[0124] - Electrochemical Impedance Spectroscopic (EIS) Analysis

[0125] The test was performed by applying an AC voltage of 10 mV in a frequency range of 0.01 Hz to 100 kHz, and the charge transfer resistance and ion diffusion characteristics were analyzed through the acquired Nyquist plot.

[0126] Example 1

[0127] Synthesis of nitrogen-containing (doped) bacterial cellulose (BNC)

[0128] - Preparation of strain and activation culture

[0129] To produce amine-containing bacterial cellulose Komagataeibacter sucrofermentans The DSM15973 strain was used. The strain was cultured for activation in Hestrin-Schramm (HS) medium.

[0130] The composition of the HS medium is as follows: glucose 20 g / L, yeast extract 5 g / L, peptone 5 g / L, Na2HPO4·12H2O 2.4 g / L, and citric acid 1.1 g / L.

[0131] After inoculating the strain into HS medium, it was cultured for 48 hours under conditions of 30 ℃ and 150 rpm.

[0132] - Preparation of main culture medium

[0133] In the main culture, crude glycerol (80% purity, EMAX Solutions, Korea), a biodiesel byproduct, was diluted to 20% (v / v), and insoluble impurities were removed by centrifugation (4000 rpm, 10 min), and only the supernatant was collected and used.

[0134] Purified crude glycerol was added to HS medium at a concentration of 20 g / L as the main carbon source, and serinol (2-amino-1,3-propanediol) was added at the following concentrations to induce amine group introduction (Control: no serinol added, S1: serinol 1.0 g / L, S2: serinol 1.4 g / L, S3: serinol 1.8 g / L, S4: serinol 4.0 g / L (crude glycerol excluded, serinol alone as a carbon source)).

[0135] The initial pH of all media was adjusted to 6.0 using a 1.0 M NaOH solution.

[0136] Synthesis of bacterial cellulose by culture

[0137] After inoculating the prepared main culture medium with an activated seed culture at a ratio of 10% (v / v), static culture was performed at 30°C for 10 days.

[0138] During the culture period, a bacterial cellulose pellicle formed on the surface of the culture medium.

[0139] - Purification of bacterial cellulose

[0140] After the culture was completed, the bacterial cellulose pellicles produced were collected, immersed in a 0.1 M NaOH solution, and then heat-treated in an 80 ℃ water bath for 2 hours to remove microbial cells and residual proteins. Subsequently, the samples were washed repeatedly with deionized water until a neutral pH was achieved, and the purified samples were dried at 30 ℃ for subsequent analysis and use.

[0141] The surface morphology and structure of the obtained bacterial cellulose (BNC) were observed using a scanning electron microscope (SEM), and the results are shown in Figure 1.

[0142] According to the figure above, both the control group and the nitrogen-containing cellulose exhibited fibrous and porous structures. However, in the case of the nitrogen-containing cellulose, it was confirmed that the structure of the nitrogen-containing cellulose was relatively looser compared to the control group, and the interfiber spacing appeared wider in some areas. This is believed to be a phenomenon caused by changes in the existing hydrogen bonding pattern due to the partial introduction of amine groups into the cellulose or by electrostatic repulsion between fibers.

[0143] Analysis of bacterial cellulose production

[0144] To evaluate the effect of in-situ nitrogen doping with serinol on the biosynthesis of bacterial cellulose, the results of a quantitative analysis of the production volume according to serinol concentration are shown in Figure 2.

[0145] Referring to the figure above, the highest bacterial cellulose production of approximately 4.3 g / L was observed in the control group. However, under conditions where serinol was added, the overall production showed a decreasing trend. Under conditions S1 to S3, relatively similar production levels in the range of approximately 3.3 to 3.6 g / L were confirmed, indicating that the inhibitory effect on bacterial cellulose biosynthesis is limited when serinol is added at low concentrations. However, under condition S4, where serinol was added at 4.0 g / L and the main carbon source was removed, the bacterial cellulose production decreased to approximately 0.8 g / L.

[0146] This suggests that it is desirable for serinol to be utilized as an auxiliary carbon source during the culture process, and that excessive concentrations may induce microbial metabolic stress or osmotic imbalance in the medium, potentially inhibiting cell growth and cellulose biosynthesis. In particular, under S4 conditions, it fails to adequately support microbial energy metabolism and bacterial cellulose biosynthesis, and it is determined that metabolic overload or cytotoxic effects caused by high concentrations of serinol act as the main cause of reduced productivity.

[0147] Specialization

[0148] To confirm whether amine groups (-NH2) were successfully introduced as nitrogen functional groups into the synthesized bacterial cellulose, analysis was performed using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and an elemental analyzer (EA).

[0149] - FTIR analysis was performed to determine whether nitrogen functional groups were introduced into the bacterial cellulose by the addition of serinol, and the results are shown in Figure 3.

[0150] Referring to the figure above, a characteristic peak confirming the cellulose skeletal structure was observed in all samples. This is approximately 3340 cm⁻¹. -1 OH stretching vibration at, approx. 2900 cm -1 Nearby CH expansion vibration, and about 1050 cm -1 Includes COC ether bond vibrations, etc. In the samples with added serinol (S1-S4), 1560-1650 cm -1 NH bending vibration in the region, and 1300-1400 cm -1 The CN stretching vibration characteristic peak increased significantly in the region. In particular, for samples S2 and S3, at 3300–3500 cm -1 The wide range of NH stretching vibration bands showed a tendency to appear more strongly.

[0151] These characteristics suggest that serinol containing both hydroxyl and amine groups was chemically incorporated into the cellulose matrix during the synthesis process through hydrogen bonding, esterification reactions, and / or microbial metabolic modification. The above effects were most pronounced in samples S2 and S3, where the associated peak intensity was clearly increased.

[0152] - XPS analysis was performed to precisely analyze the chemical bonding state of nitrogen in the sample. The results are shown in Figures 4a to 4e.

[0153] Referring to the above figure, nitrogen signals were detected in the control group (BNC) without added serinol and in all samples (S1 to S4) with added serinol, and the signals were observed to have decomposed into different chemical bonding states.

[0154] In the control group BNC, peaks corresponding to primary amines (-NH2) and NCs (amine or amide bonds) were identified at approximately 399.8 eV and 400.9 eV, respectively. These nitrogen signals are believed to originate from residues of nitrogen-containing components in the medium, such as yeast extract and peptone, and are interpreted as reflecting background nitrogen introduction unrelated to serinol.

[0155] On the other hand, for samples S1 to S4 to which serinol was added, the NC peak was commonly maintained, and at the same time, a protonated amine group (NH3) at around 401.5 eV + A new peak corresponding to ) was distinctly observed. In particular, under conditions S2 and S3, NH3 + The peak appeared most distinctly and strongly, suggesting that serinol was effectively introduced during the biosynthesis of bacterial cellulose. This NH3 + The increase in the peak indicates that the amine group of serinol may have been protonated in a weakly acidic environment during culture, or chemically bonded simultaneously with microbial metabolic processes or the formation of a cellulose matrix.

[0156] NC and NH3 across serinol-added samples +The simultaneous observation of peaks strongly suggests that serinol is not merely physically adsorbed onto the surface of bacterial cellulose, but is chemically linked to the interior of the bacterial cellulose structure through microbial metabolism, hydrogen bonding, and / or spontaneous chemical bonding.

[0157] The aforementioned XPS analysis results are consistent with the FTIR analysis results and support the fact that serinol is structurally integrated during the BNC biosynthesis step to directly produce bacterial cellulose containing nitrogen functional groups. In particular, NH3 + The appearance of the peak serves as a unique indicator of nitrogen introduction following serinol treatment, supporting the potential for subsequent applications in carbonization processes and energy storage materials.

[0158] - Nitrogen content was quantitatively analyzed through elemental analysis of the control group and each of samples S1 to S4. The results are shown in Table 1 below.

[0159] Sample Nitrogen (wt%) Carbon (wt%) Hydrogen (wt%) Oxygen (wt%) BNC 0.35 42.39 6.19 44.9 S1 0.44 42.61 6.2 47.53 S2 0.49 42.71 6.3 44.51 S3 0.74 43.34 6.33 43.72 S4 0.45 42.78 6.16 43.97

[0160] Referring to the table above, the nitrogen content of the control group (BNC) was 0.35 wt%, which is determined to be due to residual nitrogen derived from the medium.

[0161] Meanwhile, when serinol was added, the nitrogen content gradually increased to S1 (0.44 wt%), S2 (0.49 wt%), S3 (0.74 wt%), and S4 (0.45 wt%), and the highest nitrogen content was observed under condition S3.

[0162] The above results are consistent with the XPS analysis showing that the S3 sample exhibited the strongest and most balanced N 1s signal, and also imply that the amount of nitrogen introduced into the BNC and the binding type can be controlled depending on the serinol concentration. Thus, it suggests that the structural characteristics of nitrogen-doped (functionalized) bacterial cellulose can be controlled by controlling the concentration of serinol.

[0163] Example 2

[0164] Synthesis of nitrogen-containing (doped) carbon materials

[0165] A nitrogen-doped bacterial cellulose-based carbon material was prepared by performing a two-step heat treatment on the nitrogen-containing (doped) bacterial cellulose synthesized in Example 1.

[0166] First, for thermal stabilization, the sample was heated to 240 ℃ in an air atmosphere at a heating rate of 1 ℃ / min and then maintained at that temperature for 1 hour. Subsequently, the structural stability of the precursor was ensured by maintaining it at the same temperature (240 ℃) for an additional 2 hours (first heat treatment).

[0167] In the next step, the stabilized sample was heated to 800 ℃ at a heating rate of 5 ℃ / min under an argon atmosphere, and carbonization treatment was performed by maintaining the final temperature for 2 hours (second heat treatment).

[0168] After the carbonization treatment was completed, the generated carbon material was subjected to KOH activation treatment. Subsequently, it was thoroughly washed with deionized water until a neutral pH was reached, dried, and utilized for subsequent characterization and as an electrode material.

[0169] Specialization

[0170] - Nitrogen adsorption / desorption isotherm and BJH analysis were performed on samples (cS2 and cS3) obtained by carbonizing bacterial cellulose prepared under conditions where serinol was added at 1.4 g / L and 1.8 g / L, respectively, and the results are shown in Figure 5.

[0171] Referring to the figure above, the BET specific surface areas of the cS2 sample and the cS3 sample were approximately 998.7 m² / g and 775.7 m² / g, respectively, and the total pore volumes were approximately 0.69 cm³ / g and 0.44 cm³ / g, respectively. The specific surface area and pore volume of cS2 were at a higher level compared to cS3, and regarding pore size, the cS2 sample and the cS3 sample were approximately 2.75 nm and approximately 2.26 nm, respectively. In this regard, the relatively high specific surface area and micropore characteristics of the cS2 sample and the cS3 sample can be advantageous for ion transport and charge accumulation.

[0172] - High-resolution X-ray photoelectron spectroscopy (High-resolution XPS) analysis was performed on a sample (cS3) obtained by carbonizing bacterial cellulose prepared under conditions with the addition of 1.8 g / L of serinol. The results are shown in Figure 5.

[0173] Referring to the figure above, peaks were identified in the C 1s spectrum at approximately 284.6 eV (CC / C=C), 285.9 eV (CO / CN), 287.3 eV (C=O), and 288.9 eV (OC=O). This indicates that the graphite structure and oxygen and nitrogen-containing functional groups remain even after carbonization.

[0174] In the N 1s spectrum, all three nitrogen bonding states were identified: pyridinic-N (approx. 398.4 eV), pyrrolic-N (approx. 400.1 eV), and graphitic-N (approx. 401.2 eV). In particular, cS3 showed a relatively high proportion of graphitic-N. This is attributed to high structural alignment (graphitization) during the carbonization process.

[0175] Electrochemical performance evaluation

[0176] The electrochemical applicability of nitrogen-doped carbon materials obtained by carbonizing bacterial cellulose (BNC) prepared with added serinol was evaluated. Specifically, cyclic voltammetry (CV), constant current charge / discharge (GCD), and electrochemical impedance (EIS) analyses were performed on carbon material samples prepared with added serinol (cS1 to cS3) and a control group without added serinol (cBNC).

[0177] The electrochemical performance of the electrode material prepared according to the present embodiment was evaluated using a ZIVE SP1 electrochemical measuring device (Won-A-Tech, Republic of Korea). A 1 M aqueous potassium hydroxide (KOH, Alfa Aesar, USA, 85%) solution was used as the electrolyte, and measurements were performed using a standard three-electrode system configuration. A platinum wire was used as the auxiliary electrode, a saturated Ag / AgCl electrode as the reference electrode, and a glass carbon (GC) electrode with a diameter of 3 mm was used as the working electrode.

[0178] Before measurement, the GC electrode was mechanically polished using 0.3 µm and 0.05 µm alumina abrasives, and the surface was purified by sequentially washing with deionized water, ethanol (99.5%), and acetone (94.5%).

[0179] The electrode slurry was prepared by dispersing 5 mg of activated carbon material in 0.2 mL of 2-propanol (99.5%), adding 10 μL of a 5 wt% Nafion aqueous solution (Alfa Aesar, USA) to improve conductivity and adhesion, and ultrasonically dispersing over several hours. 4 μL of the prepared slurry was drop-cast onto the surface of a GC electrode and dried at 60 °C for 6 hours to fix the electrode layer.

[0180] - Cyclic Volammetry (CV) Analysis

[0181] CV analysis was performed on each of the samples cS1 to cS3 and cBNC, and the results are shown in Fig. 7a. Referring to the figure, the cS3 sample exhibited a semi-rectangular curve at a scan rate of 5 mV / s, which exhibits typical electric double layer capacitance (EDLC) behavior, while the distorted shape at the edges of the curve suggests the presence of a pseudocapacitance contribution originating from nitrogen functional groups. These results indicate that nitrogen functional groups introduced from serinol are substantially contributing to charge storage.

[0182] - Constant Current Charge / Discharge (GCD) Analysis

[0183] GCD analysis was performed on each of the samples cS1 to cS3 and cBNC, and the results are shown in Fig. 7b. Referring to the figure, the cS3 sample exhibited a symmetric and stable charge-discharge curve at a current density of 1 A / g, confirming excellent capacitor characteristics. At this time, the calculated capacitance for the cS3 sample was measured to be 510 F / g, showing significantly improved charge storage performance compared to the control carbon material (cBNC) without added serinol.

[0184] - Electrochemical Impedance Analysis (EIS)

[0185] EIS analysis was performed on each of the samples cS1 to cS3 and cBNC, and the results are shown in Fig. 7c. Referring to the figure, the series resistance (Rs) of the cS3 sample was measured to be 8.4 Ω, confirming that the internal resistance was effectively reduced by nitrogen doping. This means that the in-situ nitrogen introduction method using serinol contributes to mitigating ion diffusion resistance at the electrode-electrolyte interface and improving electron transfer characteristics.

[0186] Considering the above points, the method of introducing nitrogen into the cellulose structure of bacterial cellulose in-situ using amine-based compounds such as serinol can provide a carbon material capable of simultaneously securing graphitic conductive and electrochemically active sites without separate chemical treatment, which supports the possibility of utilizing it as an electrode material for high-performance electrochemical devices (especially energy storage devices such as supercapacitors).

[0187] Meanwhile, according to the previous BET analysis results, the larger specific surface area and pore volume of cS2 suggest a higher density of electrochemically accessible active sites, which can be considered to promote rapid ion diffusion and efficient charge storage when operating supercapacitors. The aforementioned structural advantages are reflected in a high specific capacitance of 494 F / g when evaluating electrochemical performance.

[0188] However, despite having a lower specific surface area compared to the sS2 sample, the cS3 sample exhibited the highest specific capacitance of 510 F / g. This difference implies that there are additional factors governing electrochemical behavior beyond simple pore characteristics. XPS analysis revealed that the cS3 sample possessed a more balanced nitrogen bonding configuration with increased content of graphitic-N and pyridinic-N compared to the cS2 sample. These nitrogen functional groups are known to enhance electrical conductivity and provide additional Faraday active sites, which can compensate for the limitations of the low specific surface area. In particular, graphitic-N facilitates efficient electron transfer within the carbon framework, while pyridinic-N contributes to charge storage based on pseudo-capacitance.

[0189] In conclusion, BET analysis results indicate that while high specific surface area and micropore structure are advantageous for ion transport and charge accumulation, the excellent electrochemical performance of the cS3 sample demonstrates the importance of nitrogen bonding configuration, particularly the increase in graphitic-N and pyridinic-N species, which acts as a key factor in simultaneously enhancing conductivity and redox activity. Therefore, this implies that optimal performance is achieved through a synergistic balance between pore structure and surface chemistry.

[0190] All simple variations or modifications of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims.

Claims

Claim 1 a) a step of adding a carbon source comprising an amine-based compound having at least one hydroxyl group to a microbial culture medium and performing culture by a bacterial cellulose-producing strain; a method for producing bacterial cellulose comprising, wherein the bacterial cellulose is in a form in which an amine group is introduced into the cellulose structure, and the nitrogen content in the bacterial cellulose is in the range of 0.4 to 1 weight% on an elemental basis. Claim 2 A method for manufacturing according to claim 1, wherein the bacterial cellulose-producing strain is at least one selected from the group consisting of the genus Acetobacter, the genus Gluconacetobacter, the genus Agrobacterium, the genus Rhizobium, the genus Sarcina, the genus Pseudomonas, the genus Achromobacter, the genus Alcaligenes, and the genus Aerobacter. Claim 3 A method of manufacturing according to claim 1, characterized in that the carbon source is a single carbon source of an amine-based compound having at least one hydroxyl group, or a combination of an amine-based compound having at least one hydroxyl group and other carbon-containing compounds. Claim 4 A method for manufacturing according to claim 3, wherein, when the carbon source is a single carbon source of an amine-based compound having at least one hydroxyl group, the concentration of the amine-based compound having at least one hydroxyl group in the culture medium is controlled within the range of 0.1 to 100 g / L. Claim 5 A method for manufacturing according to claim 3, wherein, when the carbon source is a combination of an amine-based compound having at least one hydroxyl group and other carbon-containing compounds, the concentration of each of the amine-based compound having at least one hydroxyl group and other carbon-containing compounds in the culture medium is controlled within the ranges of 0.1 to 4.5 g / L and 5 to 100 g / L. Claim 6 A method of manufacturing according to claim 1, wherein the other carbon-containing compound used as a carbon source is at least one selected from the group consisting of glucose, sucrose, maltose, fructose, mannose, mannitol, sorbitol, erythritol, invert sugar, cellobiose, and glycerol. Claim 7 A method for manufacturing according to claim 1, wherein the microbial culture medium is selected from the group consisting of Hestrin-Schramm (HS) medium, Yamanaka medium, Modified synthetic medium (MSM), and ZM1 medium. Claim 8 A method for manufacturing according to claim 1, characterized in that, in step a), the pH of the microbial culture medium is controlled within the range of 4 to 7. Claim 9 A manufacturing method according to claim 1, characterized in that, in step a), the culture is performed at 10 to 50 ℃ for 5 to 20 days. Claim 10 A method for manufacturing according to claim 1, characterized in that the amine-based compound having at least one hydroxyl group is an aminoalkanediol having 2 to 6 carbon atoms. Claim 11 A method of manufacturing according to claim 10, characterized in that the amine-based compound having at least one hydroxyl group is serinol. Claim 12 A method for manufacturing a nitrogen-doped carbon material comprising the step of carbonizing bacterial cellulose prepared according to any one of claims 1 to 11 through at least one heat treatment. Claim 13 A method for manufacturing a nitrogen-doped carbon material according to claim 12, wherein the heat treatment comprises a first heat treatment step and a second heat treatment step, wherein the first heat treatment step is performed at a temperature controlled in the range of 150 to 300 ℃ under an oxygen-containing atmosphere, and the second heat treatment step is performed at a temperature controlled in the range of 500 to 2000 ℃ under an inert gas atmosphere. Claim 14 A method for manufacturing a nitrogen-doped carbon material according to claim 13, characterized in that the first heat treatment and the second heat treatment are each performed for 0.5 to 5 hours and 0.5 to 5 hours, respectively. Claim 15 A method for manufacturing a nitrogen-doped carbon material according to claim 12, characterized in that the nitrogen content (doping amount) in the nitrogen-doped carbon material is controlled within the range of 2 to 5 weight% on an elemental basis. Claim 16 A method for manufacturing a nitrogen-doped carbon material according to claim 12, wherein the nitrogen-doped carbon material comprises all of the bonded states of pyridine-type nitrogen, pyrrole-type nitrogen, and graphite-type nitrogen upon XPS analysis. Claim 17 A method for manufacturing a nitrogen-doped carbon material according to claim 16, characterized in that the content of each of the pyridine-type nitrogen, pyrrole-type nitrogen, and graphite-type nitrogen in the nitrogen-doped carbon material is in the range of 0.2 to 1 weight%, 1 to 1.8 weight%, and 0.5 to 1.5 weight%. Claim 18 Electrode material for an electrochemical device comprising a nitrogen-doped carbon material manufactured in accordance with paragraph 12. Claim 19 An electrode material for an electrochemical device, characterized in that, in claim 18, the electrochemical device is a supercapacitor.

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