Carbon precursor composition and method for manufacturing carbon structure using same

Abstract

A carbon precursor composition according to an embodiment of the present invention is used for manufacturing a carbon structure having a plurality of pores, and contains, in wt%, 20-40% of a polymer precursor mixture, 10-20% of a crosslinking agent, 40-70% of a surfactant, and 0-5% of a solvent or impurities, wherein the polymer precursor mixture includes a dihydroxybenzene-based isomer, and the crosslinking agent is an aromatic compound containing two aldehyde groups.

Description

Carbon precursor composition and method for manufacturing a carbon structure using the same

[0001] The present invention relates to a carbon precursor composition and a method for manufacturing a carbon structure using the same, and more specifically, to a method for manufacturing a carbon structure capable of uniformly controlling the pore size of the carbon structure. Furthermore, the invention relates to a precursor composition of a carbon structure in which a mesopore region is uniformly developed.

[0002] Porous carbon structures possess high specific surface area and diverse pore structures, playing an essential role in fields such as energy storage, catalysis, and environmental purification. In particular, in energy storage devices such as lithium-ion batteries, carbon structures can be utilized as electrode materials by facilitating the smooth movement of lithium ions, which can contribute to increasing energy efficiency and extending battery life.

[0003] With the recent use of silicon in battery anodes, the issue of volume expansion during charging and discharging has become a critical concern. Since silicon undergoes significant volume expansion upon absorbing lithium, a carbon structure with an appropriate porous structure capable of buffering this expansion is required. If the pores are too small, silicon may not be sufficiently inserted into the structure, potentially limiting energy storage capacity; conversely, if the pores are too large, the expansion cannot be controlled, which can compromise the stability of the structure.

[0004] Therefore, technologies for precisely controlling the pore size and volume of carbon structures are being actively researched. Pores with appropriate size and volume can effectively buffer the volume expansion of silicon, reducing structural damage and consequently improving the performance and durability of the battery.

[0005] One aspect of the present invention for solving the aforementioned problems is to provide a method for manufacturing a carbon structure capable of precisely controlling the pore size and volume of the carbon structure. Additionally, the invention aims to provide a precursor composition of a carbon structure in which the mesopore region is uniformly developed to enhance compatibility with silicon materials.

[0006] The technical problems to be solved in this document are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this invention belongs from the description below.

[0007] As a means to achieve the above-mentioned purpose, a carbon precursor composition according to an embodiment of the present invention is a carbon precursor composition for manufacturing a carbon structure having a plurality of pores, comprising, in weight%, 20 to 40% of a polymer precursor mixture, 10 to 20% of a crosslinking agent, 40 to 70% of a surfactant, and 0 to 5% of a solvent or impurity, wherein the polymer precursor mixture comprises a dihydroxybenzene-based isomer, and the crosslinking agent is an aromatic compound comprising at least two aldehyde groups.

[0008] The above polymer precursor mixture includes a combination of one or more of resorcinol, catechol, hydroquinone, dihydroxynaphthalene, and dihydroxyatracene.

[0009] The above polymer precursor mixture further comprises a dihydroxynaphthalene-based compound or a dihydroxyatracene-based compound.

[0010] The above polymer precursor mixture comprises, in weight percent, 15 to 30% resorcinol and 70 to 85% hydroquinone.

[0011] The above polymer precursor mixture comprises, in weight percent, 50 to 80% resorcinol and 20 to 50% dihydroxynaphthalene.

[0012] The above polymer precursor mixture comprises, in weight percent, 30 to 50% resorcinol and 50 to 70% catechol.

[0013] The above crosslinking agent is any one of terephthalaldehyde, glutaraldehyde, malealdehyde, oxalaldehyde, phthalaldehyde, and adifaldehyde.

[0014] The above surfactant is any one of a polyoxyethylene block copolymer, a Tween-series surfactant, or an ionic surfactant.

[0015] A method for manufacturing a carbon structure according to an embodiment of the present invention comprises, in weight percent, a step of preparing a carbon precursor composition comprising 20 to 40% of a polymer precursor mixture, 10 to 20% of a crosslinking agent, 40 to 70% of a surfactant, and 0 to 5% of a solvent or impurity, and a step of heat-treating the carbon precursor composition to form a carbon structure having a plurality of pores, wherein in the step of preparing the carbon precursor composition, the polymer precursor mixture comprises at least one of a dihydroxybenzene-based compound, a dihydroxynaphthalene-based compound, and a dihydroxyatracene-based compound, and the step of preparing the carbon precursor composition comprises: a step of setting the size and volume of the pores of the carbon structure; and a step of adjusting the composition ratio of the compounds included in the polymer precursor mixture to correspond to the set size and volume of the pores.

[0016] The above polymer precursor mixture includes one or more of resorcinol, catechol, hydroquinone, dihydroxynaphthalene, and dihydroxyatracene.

[0017] The size of each of the above-set pores is 4 to 10 nm.

[0018] The volume of the pores set above is 0.5 to 0.7 cm 3 / g is.

[0019] The polymer precursor mixture comprises, in weight percent, 15 to 30% resorcinol and 70 to 85% hydroquinone, and the pore size of the carbon structure is 4 to 10 nm.

[0020] The above polymer precursor mixture comprises, in weight percent, 50 to 80% resorcinol and 20 to 50% dihydroxynaphthalene.

[0021] The above polymer precursor mixture comprises, in weight percent, 30 to 50% resorcinol and 50 to 70% catechol.

[0022] The heat treatment step comprises the step of increasing the temperature from room temperature to 400℃ at a heating rate of 1℃ / min, the step of maintaining at 380 to 420℃ for 3 hours, the step of increasing the temperature from 400 to 1000℃ at a heating rate of 5℃ / min, the step of maintaining at 950 to 1050℃ for 1 hour, and the step of cooling.

[0023] The above crosslinking agent is any one of terephthalaldehyde, glutaraldehyde, malealdehyde, oxalaldehyde, phthalaldehyde, and adifaldehyde.

[0024] The above surfactant is any one of a polyoxyethylene block copolymer, a Tween-series surfactant, or an ionic surfactant.

[0025] According to one aspect of the present invention, the volume and size of the pores of a carbon structure can be precisely and uniformly controlled. As the mesopore region of the carbon structure is uniformly developed, the silicon deposition efficiency and stability are increased, and furthermore, the charge / discharge life and performance of the electrode material can be improved.

[0026] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0027] Figure 1 is a diagram showing examples of constituent materials of a carbon precursor composition in chemical structural formulas.

[0028] FIG. 2 is a diagram showing an example of a polymer precursor according to an embodiment of the present invention in terms of chemical structure.

[0029] FIG. 3 is a diagram showing an example of a polymer precursor according to another embodiment of the present invention in terms of chemical structure.

[0030] Figure 4 is a diagram illustrating the crosslinking between a crosslinking agent and a polymer precursor.

[0031] Figure 5 is a diagram illustrating the pore sizes according to the type of polymer precursor.

[0032] Figure 6 is a graph showing the heat treatment curve of the carbonization process of a carbon precursor composition according to an embodiment of the present invention.

[0033] Figure 7 is a graph showing the change in pore distribution according to the amount of silicon deposited.

[0034] FIG. 8 is an electron microscope image showing silicon deposited on a carbon structure according to an embodiment of the present invention.

[0035] Figure 9 is an electron microscope image showing silicon over-deposited on a carbon structure according to a comparative example.

[0036] Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those with average knowledge in the relevant technical field.

[0037] The terms used in this application are used merely to describe specific examples. For this reason, singular expressions include plural expressions unless the context clearly requires them to be singular. Additionally, it should be noted that terms such as “comprising” or “comprising” used in this application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and are not used to preliminarily exclude the existence of other features, steps, functions, components, or combinations thereof.

[0038] Meanwhile, unless otherwise defined, all terms used in this specification shall be understood to have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Accordingly, unless explicitly defined in this specification, specific terms should not be interpreted in an overly ideal or formal sense. For instance, singular expressions in this specification include plural expressions unless the context clearly indicates an exception.

[0039] Additionally, terms such as "about," "substantially," etc., in this specification are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said sense, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosed content in which precise or absolute values ​​are mentioned to aid in understanding the invention.

[0040] A carbon precursor composition according to one embodiment of the present invention and a method for manufacturing a carbon structure including the same will be described in detail below.

[0041] A method for manufacturing a carbon structure according to an embodiment of the present invention comprises the steps of: manufacturing a carbon precursor composition; and heat-treating the carbon precursor composition to form a carbon structure having a plurality of pores.

[0042] A carbon precursor composition according to an embodiment of the present invention may comprise 20 to 40% of a polymer precursor mixture, 10 to 20% of a crosslinking agent, 40 to 70% of a surfactant, and 0 to 5% of a solvent or impurity.

[0043] According to the present embodiment, the compositional ratio of compounds included in the polymer precursor mixture can be adjusted according to the size and volume of the pores of the carbon structure to be manufactured. That is, the step of manufacturing the carbon precursor composition may include the step of setting the size and volume of the pores of the carbon structure and the step of adjusting the compositional ratio of compounds included in the polymer precursor mixture to correspond to the set size and volume of the pores.

[0044] In a preferred embodiment, the size of the pores of the carbon structure may each be 4 to 10 nm, and the volume of the pores may be 0.5 to 0.7 cm³ 3 It may be / g. That is, in a preferred embodiment, the carbon structure may include a plurality of uniformly distributed mesopores. The volume is defined as the volume occupied by the pores per unit weight of the carbon structure.

[0045] Figure 1 is a diagram showing examples of constituent materials of a carbon precursor composition in chemical structural formulas.

[0046] The polymer precursor mixture combines with the crosslinking agent (CL) to form the carbon skeleton of the carbon structure (MT) to be described later, and acts as the main carbon raw material for the carbon structure (MT).

[0047] In another embodiment of the present invention, the polymer precursor mixture may be mixed with other functional materials or additives to contribute to controlling electrical conductivity or surface chemical activity, etc.

[0048] In an embodiment of the present invention, the content of the polymer precursor mixture may be 20 to 40%. If the content of the polymer precursor mixture is less than 20%, the content of the polymer precursor is insufficient, so a stable pore structure cannot be formed during the carbonization process (heat treatment process), and there is a high possibility that pores will be formed unevenly.

[0049] On the other hand, if the content of the polymer precursor mixture is excessive, the pore density may decrease or the pores may become denser, potentially reducing the pore volume. Additionally, there is a high likelihood that fine pores will form due to an excessive amount of carbon precursor. When silicon is deposited within the pores of a carbon structure to be subsequently used as a cathode material, silicon may not be deposited in the fine pores.

[0050] Therefore, the content of the polymer precursor mixture is suitable to be 20 to 40%.

[0051] In an embodiment of the present invention, the polymer precursor mixture may include at least one of a dihydroxybenzene-based compound, a dihydroxynaphthalene-based compound, and a dihydroxyatracene-based compound. That is, the polymer precursor mixture may include a compound having two or more hydroxyl groups on at least one benzene ring.

[0052] In an embodiment of the present invention, the polymer precursor mixture may include a combination of one or more of resorcinol, catechol, hydroquinone, dihydroxynaphthalene, and dihydroxyatracene. In FIGS. 2 and 3, examples of compounds included in the polymer precursor mixture are illustrated by their chemical structural formulas.

[0053] In a preferred embodiment of the present invention, the size of each pore is 4 to 10 nm, and the volume of the pores is 0.5 to 0.7 cm³ 3 When manufacturing a carbon structure with a g content, the polymer precursor mixture may contain only resorcinol.

[0054] In another preferred embodiment of the present invention, the size of each pore is 4 to 10 nm, and the volume of the pores is 0.5 to 0.7 cm³ 3 When manufacturing a carbon structure of / g, the polymer precursor mixture essentially includes resorcinol, but may additionally include one of catechol, hydroquinone, dihydroxynaphthalene, and dihydroxyatracene.

[0055] For example, when the polymer precursor mixture comprises resorcinol and hydroquinone, the polymer precursor mixture may comprise 15 to 30% resorcinol and 70 to 85% hydroquinone in weight percent.

[0056] When hydroquinone is contained in an amount of 70% or more, it reacts well with the crosslinking agent due to the positional characteristics of the hydroxyl groups, allowing for the formation of uniform mesopores. However, if the hydroquinone content exceeds 85%, the pore structure may become excessively dense, and this dense structure reduces the free space within the mesopores, which can lead to a decrease in pore volume.

[0057] In another example of the present invention, exemplarily, when the polymer precursor mixture comprises resorcinol and dihydroxynaphthalene, the polymer precursor mixture may comprise 50 to 80% resorcinol and 20 to 50% dihydroxynaphthalene in weight percent.

[0058] When the content of dihydroxynaphthalene exceeds 50%, the irregularity increases during cross-linking between polymer precursors (CP) due to the polycyclic aromatic structural characteristics, leading to the formation of a wide range of pores, which can increase the fraction of micropore formation. Consequently, when silicon is deposited in the internal pores, the distribution and size of the silicon may be non-uniform, making it difficult to effectively suppress volume expansion during silicon charging and discharging.

[0059] In another example of the present invention, exemplarily, when the polymer precursor mixture comprises resorcinol and catechol, the polymer precursor mixture may comprise 30 to 50% resorcinol and 50 to 70% catechol in weight percent.

[0060] The crosslinking agent (CL) plays a role in enhancing the structural stability of the final carbon structure (MT) by bonding with the polymer precursor (CP). The crosslinking agent (CL) plays a role in promoting bonding between the polymer precursors (CP). In Figure 4, the crosslinking between the crosslinking agent and the polymer precursor is illustrated.

[0061] The crosslinking agent (CL) strengthens the internal bonding strength of the final carbon structure (MT) by reacting the active groups of the polymer precursor (CP) to form strong bonds between the precursors. This bonding strength allows the shape and pore structure of the carbon structure to be maintained even during high-temperature heat treatment. In particular, the crosslinking agent (CL) forms strong crosslinking bonds through a condensation reaction between the aldehyde group (-CHO) and the hydroxyl group (-OH) of the polymer precursor (CP), thereby enabling the creation of a complex carbon network.

[0062] In one embodiment of the present invention, the crosslinking agent (CL) may be any one of terephthalaldehyde, glutaraldehyde, maleic aldehyde, oxalaldehyde (glycal), phthalaldehyde, and adipaldehyde. In a preferred embodiment, the crosslinking agent may be terephthalaldehyde (TPA).

[0063] In this embodiment, the content of the crosslinking agent (CL) in the carbon precursor mixture may be 10 to 20%.

[0064] If the content of the crosslinking agent (CL) is less than 10%, the crosslinking bonds between the polymer precursors (CP) are not sufficiently formed, which may result in a decrease in the bonding strength of the final carbon structure (MT). This may increase the likelihood that the carbon structure (MT) will easily deform or break at high temperatures. Additionally, if the crosslinking bonds are weak, the size and volume of the pores may not be uniform during the mesopore formation process.

[0065] Meanwhile, if the content of the crosslinking agent (CL) is excessively high, the bonds between the polymer precursors (CP) become excessively dense, which may result in a higher pore density or an excessive reduction in pore size. Additionally, excessive crosslinking may cause the pores inside the carbon structure (MT) to be fixed too strongly, leading to structural stress during the heat treatment process. This results in non-uniformity of the pore size distribution and reduces accessibility to the internal pores of the structure, which may lead to performance degradation when the carbon structure is used as an electrode material. Therefore, the content of the crosslinking agent (CL) is preferably 10 to 20%.

[0066] The surfactant (SF) plays a role in forming and controlling the structure of the pores. The surfactant (SF) acts as a solid template, which allows the size and location of the pore formation to be determined. The surfactant (SF) can be completely vaporized and disappear after the carbonization process. During the carbonization process, the surfactant (SF) decomposes due to heat, and pores can be formed in the locations where the surfactant (SF) was situated. The formed pores subsequently provide a pathway for lithium ion movement when the carbon precursor (MT) is used as an electrode material.

[0067] In one embodiment of the present invention, the surfactant may be any one of a polyoxyethylene block copolymer, a Tween-series surfactant, or an ionic surfactant. In a preferred embodiment, the surfactant may be F127 (PEO-PPO-PEO).

[0068] In an embodiment of the present invention, the content of the surfactant (SF) may be 40 to 70%. If the content of the surfactant (SF) is less than 40%, the role of the template for pore formation is weakened, and the formation rate of mesopores may decrease. In addition, the required free space within the carbon structure is reduced, making it difficult to secure sufficient pore size and volume, and the uniformity of the pore size distribution may decrease.

[0069] Meanwhile, if the content of the surfactant (SF) exceeds 70%, excessive templates may be formed during the pore formation process, leading to increased pore density within the structure or non-uniform pore formation. Consequently, the pore distribution becomes unstable, and excessively large pores may be formed in addition to mesopores. Furthermore, due to the excess surfactant (SF), the ratio of the polymer precursor (CP) and the crosslinking agent (CL) becomes relatively low, which may reduce the structural stability of the final carbon structure (MT). Therefore, the ratio of the surfactant (SF) is preferably 40 to 70%.

[0070] According to an embodiment of the present invention, the carbon precursor mixture (CP) may contain 0 to 5 weight percent of solvent, and in another embodiment of the present invention, the carbon precursor mixture (CP) may not contain solvent.

[0071] The method for manufacturing a carbon structure (MT) according to an embodiment of the present invention may be a solvent-free dry process. In the present invention, a solvent-free dry process is defined as using a carbon precursor mixture (CP) containing 0 to 5 weight percent of solvent. Accordingly, the carbon precursor mixture (CP) of the present invention may be in the form of a solid mixture rather than a solution. In this case, since a separate drying process to vaporize the liquid before the carbonization process is not performed, time and cost can be saved.

[0072] As described above, according to an embodiment of the present invention, the size and volume of the pores to be formed may vary depending on the type and composition ratio of the compounds included in the carbon precursor mixture (CP).

[0073] FIG. 5 is a diagram illustrating the pore sizes according to the type of polymer precursor. FIG. 5 (a), (b), and (c) conceptually illustrate carbon structures (MT1 to MT3) containing different types of polymer precursors to aid in understanding the explanation. The carbon structures illustrated in FIG. 5 (a), (b), and (c) are cases where the same number of crosslinking agents and the same number of polymer precursors are combined.

[0074] The first polymer precursor (CP1) of the first carbon structure (MT1) illustrated in (a) may be resorcinol. Resorcinol (CP1) is combined with a crosslinking agent (CL). The combined composite (PV1) forms the framework of the first carbon structure (MT1), and a first pore (PD1) may be formed inside the composite. At this time, the size of the first pore (PD1) has a first size, and the volume per unit cell of the first carbon structure (MT1) has a first volume.

[0075] The second polymer precursor (CP2) of the second carbon structure (MT2) illustrated in (b) may be hydroquinone. Hydroquinone (CP2) is combined with a crosslinking agent (CL). The combined composite (PV2) forms the framework of the second carbon structure (MT2), and a second pore (PD2) may be formed inside the composite. At this time, the size of the second pore (PD2) has a second size, and the volume per unit cell of the second carbon structure (MT2) has a second volume. The second size and the second volume may be larger than the first size and the first volume.

[0076] The third polymer precursor (CP3) of the third carbon structure (MT3) illustrated in (c) may be catechol. The catechol (CP3) is combined with a crosslinking agent (CL). The combined composite (PV3) forms the framework of the third carbon structure (MT3), and a third pore (PD3) may be formed inside the composite. In this case, the size of the third pore (PD3) has a third size, and the volume per unit cell of the third carbon structure (MT3) has a third volume. The third size and third volume may be smaller than the first size and third volume.

[0077] The above examples suggest that the pore size and the volume of the carbon structure per unit cell may vary depending on the type of polymer precursor, and according to an embodiment of the present invention, it is possible to control the pores of the carbon structure by designing a combination of compounds included in the polymer precursor mixture.

[0078] Table 1 below shows the pore volume and pore size when carbon precursors are prepared with different polymer precursor mixture compositions.

[0079] Raw Material Combination Ratio, Polymer Precursor Combination Ratio, Pore Volume, Pore Size (Weight%), Weight Ratio (cm²) 3 / g)(nm) Comparative Example 1 28.6(C):14.3(TPA):57.1(F127)-0.324.87 Example 1 28.6(R):14.3(TPA):57.1(F127)-0.675.44 Comparative Example 2 28.6(Q):14.3(TPA):57.1(F127)-0.6136.01 Comparative Example 3 28.6(N):14.3(TPA):57.1(F127)-0.7119.93 Comparative Example 4 14.3(R):14.3(Q):14.3(TPA):57.1(F127)1:1 (R:Q)0.414.97 Comparative Example 59.6(R):19.0(Q):14.3(TPA):57.1(F127)1:2 (R:Q)0.396.66 Example 27.2(R):21.4(Q):14.3(TPA):57.1(F127)1:3 (R:Q)0.538.56 Comparative Example 65.7(R):22.9(Q):14.3(TPA):57.1(F127)1:4 (R:Q)0.5612.02 Comparative Example 714.3(R):14.3(N):14.3(TPA):57.1(F127)1:1 (R:N)0.58 11.28 Example 3 22.9(R):5.7(N):14.3(TPA):57.1(F127)4:1 (R:N)0.64 9.35 Comparative Example 8 14.3(R):14.3(C):14.3(TPA):57.1(F127)1:1 (R:C)0.39 5.06 Comparative Example 9 7.2(R):21.4(C):14.3(TPA):57.1(F127)1:3 (R:C)0.33 4.51 Comparative Example 10 *-0.9 11.08 Comparative Example 11 *-1.35 50.56 R: Resorcinol, Q: Hydroquinone, N: Dihydroxynaphthalene, C: Catechol

[0080] Referring to Table 1, the analysis of the effect of using a single polymer precursor showed that in Example 1, where resorcinol was used alone, the pore size was 5.44 nm and the pore volume was 0.67 cm³. 3It exhibited the most ideal characteristics at / g. On the other hand, when catechol (Comparative Example 1), hydroquinone (Comparative Example 2), and dihydroxynaphthalene (Comparative Example 3) were used individually, the target pore characteristics were not satisfied. In particular, in the case of hydroquinone (Q) and dihydroxynaphthalene (N), excessively large pores of 36.01 nm and 19.93 nm were formed, respectively, and in the case of catechol (C), the pore volume was 0.32 cm³ 3 It was found to be very low at / g. In the case of the composite polymer precursor, first examining the conditions in which resorcinol (R) and hydroquinone (Q) were mixed, in Example 2 (R:Q=1:3), which corresponds to the range of 15-30% resorcinol (R) and 70-85% hydroquinone (Q) claimed in the present invention, the pore size was 8.56 nm and the pore volume was 0.53 cm³. 3 It exhibited excellent characteristics of / g. However, in the case of Comparative Example 4 (R:Q=1:1), Comparative Example 5 (R:Q=1:2), and Comparative Example 6 (R:Q=1:4), which fell outside this range, the pore volume was lower than the target range (0.39 to 0.41 cm). 3 / g) A problem occurred in which the pore size became excessively large (12.02 nm). This can be interpreted as the pore size increasing as the proportion of hydroquinone (Q) increases.

[0081] In the combination of resorcinol(R) and dihydroxynaphthalene(N), a condition with a high proportion of resorcinol(R) was found to be advantageous. In Example 3, under the condition R:N=4:1, the pore size was 9.35 nm and the pore volume was 0.64 cm³. 3 It showed excellent characteristics satisfying the target range with / g. On the other hand, in Comparative Example 7, where the R:N ratio was lowered to 1:1, the pore size increased to 11.28 nm, falling outside the target range. These results show that the pore size tends to increase as the content of dihydroxynaphthalene (N) increases.

[0082] Under the mixed conditions of resorcinol (R) and catechol (C) (Comparative Examples 8 and 9), the overall pore volume was low (0.33-0.39 cm²) regardless of the mixing ratio. 3 Representing / g), the 0.5-0.7cm targeted by the present invention 3 A pore volume of / g was not achieved. This is a similar trend to when catechol (C) was used alone, which is interpreted as the presence of catechol (C) inhibiting pore volume development.

[0083] Synthesizing these experimental results, the uniform mesopores (4 to 10 nm) and optimal pore volume (0.5 to 0.7 cm) targeted in the present invention 3 For the preparation of carbon structures having (g), resorcinol is the most superior as a single precursor, and when using a composite precursor, it is found that using resorcinol (R) as the main component and mixing it with hydroquinone (Q), dihydroxynaphthalene (N), or catechol (C) in appropriate proportions is most effective. In particular, it has been proven that it is important to maintain a hydroquinone (Q) ratio of 70 to 85% when mixed with hydroquinone (R), and to maintain a high ratio of resorcinol (R) when mixed with dihydroxynaphthalene (N). Figure 6 is a graph showing the heat treatment curve of the carbonization process of a carbon precursor composition according to an embodiment of the present invention.

[0084] Referring to FIG. 6, the step of heat-treating a carbon precursor composition according to an embodiment of the present invention includes the step of heating from room temperature to 400°C at a heating rate of 1°C / min, the step of maintaining at 380 to 420°C for 3 hours, the step of heating at a heating rate of 5°C / min to 400 to 1000°C, the step of maintaining at 950 to 1050°C for 1 hour, and the step of cooling.

[0085] The above first holding step may be a aging step for sufficient reaction between the compounds included in the carbon precursor composition. In this step, the bonding between the polymer precursor mixture and the crosslinking agent (CL) may be completed. Additionally, in the above step, the formation of a solid template form of the surfactant (SF) may be completed.

[0086] The above second holding step is for carbonizing the carbon precursor composition, and in this step, the decomposition of the surfactant (SF) is completed, and a pore (PR) is formed in the place where the surfactant (SF) was located. A structure composed of a polymer precursor and a crosslinking agent (CL) can form the framework of the carbon structure.

[0087] The carbon structures (MT) that have completed carbonization may aggregate with each other to form solid lump carbides. In another embodiment of the present invention, the lumps of carbon structures (MT) may additionally undergo a grinding step.

[0088] When a carbon precursor mixture having the composition ratio according to the aforementioned preferred embodiment is heat-treated according to the method, a pore size of 4 to 10 nm and 0.5 to 0.7 cm 3 It is possible to form a carbon structure having a pore volume of / g.

[0089] Figure 7 is a graph showing the change in pore distribution according to the amount of silicon deposited. The x-axis of the graph represents the size of the pores contained in the carbon structure according to an embodiment of the present invention, and the y-axis represents the volume of the pores corresponding to the pore size on the x-axis. The unit of the amount of silicon deposited is wt%, and it represents the proportion of silicon based on the total weight of the entire sample (carbon structure and silicon) of the cathode material.

[0090] Specifically, FIG. 7 is a graph showing the pore structure analysis performed after depositing silicon on porous carbon having micropores and mesopores. Here, micropores are pores with a size of 2 nm or less, and mesopores may be pores with a size of 2 to 10 nm.

[0091] Referring to Fig. 7, the pore distribution change curve when the silicon deposition amount is 0 wt% represents the distribution of pores contained in the actual carbon structure. Through the curve, it can be confirmed that micropores and mesopores coexist in the carbon structure.

[0092] Referring to the curves for silicon deposition amounts of 17 wt%, 24 wt%, and 51 wt%, it can be seen that as the deposition amount increases, the pore volume in the 2-10 nm mesopore region decreases more significantly than that in the micropores. This means that silicon is primarily deposited preferentially in the mesopores.

[0093] In the curve when the silicon deposition amount is 51 wt%, the volume in the micropore region decreases sharply, which is interpreted as silicon blocking the micropores due to excessive silicon deposition. Meanwhile, it can be confirmed that the pores in the mesopore region still maintain their pore structure despite the deposition of 51 wt% silicon.

[0094] These results demonstrate that the mesopore structure in the 4 to 10 nm range targeted in the present invention is highly effective for silicon deposition. In particular, it was confirmed that mesopores act as selective silicon deposition sites, and that mesopores of appropriate size can maintain structural stability even under excessive silicon deposition conditions. According to an embodiment of the present invention, it can be seen that as the amount of silicon deposited increases, the pore volume decreases as more pores are gradually filled by silicon. In particular, judging from the significant decrease in the volume of pores in the mesopore region compared to pores in other regions, it can be seen that silicon deposition efficiency is active in the mesopore region. That is, the carbon structure manufactured according to an embodiment of the present invention is formed to have a developed mesopore region, and accordingly, silicon deposition efficiency increases, which can increase the durability of the carbon structure.

[0095] Table 2 below shows the initial capacity and capacity retention rate after 50 charge-discharge cycles when a carbon precursor according to each of the embodiments and comparative examples of the present invention is used as a cathode material. Specifically, the initial capacity and capacity retention rate after 50 charge-discharge cycles when a carbon precursor according to Example 1 and Comparative Example 11 of Table 1 is used as a cathode material were measured and are shown in Table 2.

[0096] Initial Capacity (mAh / g) Capacity Retention Rate @50 cycle (%) Example 1 After Si Deposition 190 1.6 7 9.70% Comparative Example 11 After Si Deposition 254 3.9 15.60%

[0097] Referring to Table 2, when a carbon precursor according to an embodiment of the present invention is used as a negative electrode material, the initial capacity is 1901.6 mAh / g and the capacity retention rate may be 79.70%. On the other hand, when a carbon precursor according to a comparative example is used as a negative electrode material, the initial capacity is very high at 2543.9 mAh / g, but it may decrease rapidly to 15.60% after 50 charge-discharge cycles. This can be predicted to be because the durability of the carbon precursor according to the comparative example decreases, making it difficult to buffer the expansion of silicon. Fig. 8 is an electron microscope image showing silicon deposited on a carbon structure according to an embodiment of the present invention, and Fig. 9 is an electron microscope image showing silicon over-deposited on a carbon structure according to a comparative example.

[0098] Figures 8 and 9 are elemental distribution images of carbon structures obtained by combining electron microscope images and EDX (Elemental Dispersive X-ray Spectroscopy) analysis, respectively, with the left photograph visualizing the distribution of carbon and the right photograph visualizing the distribution of silicon.

[0099] Referring to FIGS. 8 and 9, it can be seen that in the carbon structure according to the embodiment of the present invention, silicon is uniformly deposited, whereas in the comparative example, silicon is excessively deposited and concentrated on the surface of the carbon structure.

[0100] In Fig. 8, the silicon distribution is evenly spread throughout the carbon structure, suggesting that the mesopore size and volume improved the uniform deposition efficiency of silicon. A uniform silicon distribution can be advantageous for maintaining structural stability by increasing durability against volume expansion when used as a negative electrode material for lithium-ion batteries. On the other hand, in the comparative example in Fig. 9, when silicon is excessively deposited, it can be observed that the silicon is mainly concentrated on the surface of the carbon structure and there is insufficient penetration into the interior. This can lead to pore blockage or structural imbalance, making it vulnerable to volume expansion during the charge-discharge process when used as a negative electrode material.

[0101] Consequently, according to the method for manufacturing a carbon structure according to an embodiment of the present invention, the pore size and pore volume of the carbon structure can be controlled by adjusting the type and ratio of compounds included in the polymer precursor mixture. In particular, a carbon structure with uniformly developed mesopore regions can be manufactured by adjusting the type and ratio of the polymer precursor mixture.

[0102] Although embodiments of the invention disclosed above have been illustrated and described, the disclosed invention is not limited to the specific embodiments described above, and various modifications may be made by those skilled in the art to which the disclosed invention belongs without departing from the essence claimed in the claims.

Claims

1. A carbon precursor composition for manufacturing a carbon structure having multiple pores, It comprises, in weight percent, 20 to 40% of a polymer precursor mixture, 10 to 20% of a crosslinking agent, 40 to 70% of a surfactant, and 0 to 5% of a solvent or impurity, and The above polymer precursor mixture includes a dihydroxybenzene-based isomer, and The above-mentioned crosslinking agent is a carbon precursor composition that is an aromatic compound containing at least two aldehyde groups.

2. In Paragraph 1, The above polymer precursor mixture is a carbon precursor composition comprising a combination of one or more of resorcinol, catechol, hydroquinone, dihydroxynaphthalene, and dihydroxyatracene.

3. In Paragraph 1, The above polymer precursor mixture is a carbon precursor composition further comprising a dihydroxynaphthalene-based compound or a dihydroxyatracene-based compound.

4. In Paragraph 1, The above polymer precursor mixture is a carbon precursor composition comprising, in weight percent, 15 to 30% resorcinol and 70 to 85% hydroquinone.

5. In Paragraph 1, The above polymer precursor mixture is a carbon precursor composition comprising, in weight percent, 50 to 80% resorcinol and 20 to 50% dihydroxynaphthalene.

6. In Paragraph 1, The above polymer precursor mixture is a carbon precursor composition comprising, in weight percent, 30 to 50% resorcinol and 50 to 70% catechol.

7. In Paragraph 1, The above crosslinking agent is a carbon precursor composition that is any one of terephthalaldehyde, glutaraldehyde, malealdehyde, oxalaldehyde, phthalaldehyde, and adifaldehyde.

8. In Paragraph 1, The above surfactant is a carbon precursor composition that is any one of a polyoxyethylene block copolymer, a Tween-series surfactant, or an ionic surfactant.

9. A step of preparing a carbon precursor composition comprising, at weight%, 20 to 40% polymer precursor mixture, 10 to 20% crosslinking agent, 40 to 70% surfactant, and 0 to 5% solvent or impurities; and The method includes the step of heat-treating the carbon precursor composition to form a carbon structure having a plurality of pores, and In the step of preparing the carbon precursor composition, the polymer precursor mixture comprises at least one of a dihydroxybenzene-based compound, a dihydroxynaphthalene-based compound, and a dihydroxyatracene-based compound, and The step of preparing the above carbon precursor composition is, Step of setting the size and volume of the pores of the carbon structure; and A method for manufacturing a carbon structure comprising the step of adjusting the composition ratio of compounds included in the polymer precursor mixture to correspond to the size and volume of the pores set above.

10. In Paragraph 9, A method for preparing a carbon structure comprising the above polymer precursor mixture, one or more of resorcinol, catechol, hydroquinone, polyhydroxynaphthalene, and polyhydroxyatracene.

11. In Paragraph 10, A method for manufacturing a carbon structure in which the size of each of the above-set pores is 4 to 10 nm.

12. In Paragraph 10, The volume of the pores set above is 0.5 to 0.7 cm 3 Method for manufacturing carbon structures with a phosphorus content of 1g.

13. In Paragraph 10, The above polymer precursor mixture comprises, in weight percent, 15 to 30% resorcinol and 70 to 85% hydroquinone, and A method for manufacturing a carbon structure in which the pore size of the carbon structure is 4 to 10 nm.

14. In Paragraph 10, A method for preparing a carbon structure, wherein the polymer precursor mixture comprises, in weight percent, 50 to 80% resorcinol and 20 to 50% dihydroxynaphthalene.

15. In Paragraph 10, A method for preparing a carbon structure, wherein the polymer precursor mixture comprises, in weight percent, 30 to 50% resorcinol and 50 to 70% catechol.

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