Method for manufacturing porous ceramic material for lithium ion capacitor having controlled pore structure and porous ceramic material for lithium ion capacitor manufactured by the same

Abstract

The present invention relates to a method for manufacturing a ceramic porous body comprising: a solution forming step of forming a solution containing a ceramic precursor and a carbon precursor; a first powder forming step of drying the solution to form a first powder; a first heat treatment step of converting the first powder into a second powder containing ceramic and carbon by pyrolysis; and a second heat treatment step of oxidizing the carbon of the second powder, and to a ceramic porous body manufactured thereby.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure and a ceramic porous body for a lithium-ion capacitor manufactured thereby, wherein macropores are formed on the surface and mesopores are formed inside, thereby having excellent ion storage and ion emission capabilities, and exhibiting high oxidation resistance, high heat resistance, and excellent structural stability, and a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure and a ceramic porous body for a lithium-ion capacitor manufactured thereby. Background Technology

[0003] A lithium-ion capacitor (LIC) is a hybrid capacitor that utilizes a lithium-doped carbon-based material as the negative electrode and capacitor materials, such as activated carbon or polymer-based organic semiconductors used in conventional electric double-layer capacitors, as the positive electrode. During charging, lithium ions are separated from the surface of the positive electrode material, pass through the electrolyte and separator, and are inserted into the negative electrode material; during discharging, lithium ions are separated from the negative electrode material and return to the positive electrode material through the electrolyte. An electric double layer is formed on the surface by the positive charge. Due to its asymmetric structure, lithium-ion capacitors are suitable for power quality applications requiring high energy density, high power density, environmental durability, and robustness.

[0004] In order to secure excellent characteristics of carbon-based materials used as electrode materials for lithium-ion capacitors, it is important to increase the specific surface area by having structures such as mesopores and macropores so that a large amount of lithium ions can be stored and released at once, and also to have thermal stability depending on the usage environment and not cause swelling even if charging and discharging are repeated.

[0005] Graphite can be cited as an example of a carbon-based material for lithium-ion capacitors. Graphite has the advantage of being easy to form micropores and maximizing its specific surface area. However, as charging and discharging cycles are repeated, a large amount of lithium ions are inserted and ejected, causing structural deformation. This can lead to swelling and explosion, and thermal instability has been pointed out as a problem.

[0006] Meanwhile, ceramic porous materials are being applied in various industrial fields by actively utilizing pores formed on their surfaces and within. Representative application areas include dust collection filters, catalysts and catalyst carriers, adsorbents, thermal insulation materials, filtration materials, electrode materials, artificial biomaterials, lightweight structural materials, and shock absorbers.

[0007] A representative method for manufacturing porous ceramics is the template method, which involves adding polymer microparticles with different properties as additives to a ceramic material to form a specific shape, and then removing only the polymer microparticle portion to create pores.

[0008] Polymer-derived ceramics ('PDC') can be manufactured by converting a polymer precursor into a ceramic through thermal decomposition. Unlike conventional sintered ceramic bodies, polymer-derived ceramics produced in this way are manufactured without sintering aids and possess excellent oxidation resistance and creep resistance. Additionally, during the process of converting from polymer to ceramic, ceramic crystals are formed and grown in a nano-sized form, which can exhibit other properties. Depending on the requirements of the application field, polymer-derived ceramics may have a dense structure or a porous structure with macropores or mesopores by controlling the thermal decomposition process.

[0009] In addition, polymer-derived ceramics such as SiC (Silicon carbide) exhibit excellent durability and stability in extreme environments, particularly due to their very high oxidation resistance temperature. Therefore, when formed into porous materials, they can be applied in various fields such as electrode materials for lithium-ion capacitors or lithium-ion batteries, catalysts, filters, thermal insulation materials, artificial biomaterials, lightweight structural materials, and shock absorbers.

[0010] Patent Document 1 relates to an expanded graphite anode material for a lithium-ion capacitor in which lithium is impregnated into expanded graphite. The invention discloses a manufacturing process for an anode material in which expanded graphite is expanded and used, and a lithium compound is impregnated between layers of expanded graphite. The process includes the steps of expanding graphite, micronizing expanded graphite, impregnating the micronized expanded graphite with lithium hydroxide and lithium cobalt oxide (Li6CoO4) in a vacuum, dissolving the vacuum-immersed expanded graphite and polyacrylate, which is a water-based binder, in distilled water, which is a solvent, and then forming the solutiond binder into a slurry and sheet to produce an anode for a lithium-ion capacitor.

[0011] Patent Document 2 relates to a negative electrode active material for a lithium secondary battery and a lithium secondary battery including the same, and discloses a method for manufacturing a negative electrode active material for a lithium secondary battery comprising the steps of: preparing carbon-based particles having pores having a size of 20 nm or less; introducing a silicon-based compound gas into the carbon-based particles; and calcining the carbon-based particles and the silicon-based compound gas together to deposit silicon inside or on the surface of the pores of the carbon-based particles.

[0012] Conventional technology refers to technical information that the inventor possessed for the derivation of the present invention or acquired during the process of deriving the present invention, and it cannot necessarily be considered publicly known technology disclosed to the general public prior to the filing of the present invention. Prior art literature

[0014] Republic of Korea Registered Patent No. 10-2057128 (Registered Dec. 12, 2019) Republic of Korea Registered Patent No. 10-2788437 (Registered Mar. 25, 2025) The problem to be solved

[0015] In resolving the aforementioned problems, the objective of the present invention is to provide a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure in which macropores are formed on the surface and mesopores are formed inside, thereby possessing excellent ion storage and ion emission capabilities, as well as exhibiting high oxidation resistance, high heat resistance, and excellent structural stability.

[0016] Furthermore, the objective of the present invention is to provide a ceramic porous body for a lithium-ion capacitor having a controlled pore structure that can be efficiently applied in a wide range of fields, such as electrode materials for lithium-ion capacitors or lithium-ion batteries, catalysts, filters, thermal insulation materials, artificial biomaterials, lightweight structural materials, and shock absorbers, by having a pore structure appropriately controlled to satisfy the characteristics required in the field of application.

[0017] The problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned will be clearly understood by a person skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0019] A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention comprises: a solution forming step of forming a solution comprising a ceramic precursor and a carbon precursor; a primary powder forming step of drying the solution to form a primary powder; a primary heat treatment step of converting the primary powder into a secondary powder comprising ceramic and carbon by pyrolysis; and a secondary heat treatment step of oxidizing the carbon of the secondary powder.

[0020] At this time, the ceramic precursor may be one or more selected from the group consisting of polycarbosilane ('PSC'), polysilazne, polyborosilazne, and polysiloxanes.

[0021] In addition, the carbon precursor may include a material that is converted into carbon by the pyrolysis.

[0022] In this case, the carbon precursor may be added in a weight ratio of 30 to 70 percent relative to the ceramic precursor.

[0023] In the above embodiment, the first powder forming step may include drying the solution under vacuum for 18 to 30 hours.

[0024] A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention may further include a step of performing oxidation curing by applying hot air at 150 to 200°C to the primary powder for 8 to 12 hours after the primary powder forming step.

[0025] In addition, the above first heat treatment can be performed at a temperature in the range of 1500 to 1600℃.

[0026] A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention may further include, after the first heat treatment step, a grinding step in which the second powder is ground using a ball mill for 20 to 30 hours; and a sieving step.

[0027] At this time, the above sieving step can be performed using a standard sieve of 80 to 120 μm.

[0028] In addition, the above second heat treatment step can be performed in air at a temperature in the range of 550 to 750°C.

[0029] Meanwhile, a ceramic porous body according to another embodiment of the present invention can be manufactured by a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to the above-described embodiment.

[0030] At this time, the above-mentioned ceramic porous body can be used as a material for a lithium-ion capacitor. Effects of the invention

[0032] As described above, according to the method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to the present invention, macropores are formed on the surface and mesopores are formed inside, thereby providing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure that has excellent ion storage and ion emission capabilities, and exhibits high oxidation resistance, high heat resistance, and excellent structural stability.

[0033] In addition, the ceramic porous body produced by the method for producing a ceramic porous body according to the present invention has a pore structure appropriately controlled to satisfy the characteristics required in the field of application, and can be efficiently applied in a wide range of fields such as electrode materials for lithium-ion capacitors or lithium-ion batteries, catalysts, filters, thermal insulation materials, artificial biomaterials, lightweight structural materials, and shock absorbers.

[0034] In addition, the ceramic porous body produced by the method for producing a ceramic porous body according to an embodiment of the present invention can exhibit superior performance, particularly as an electrode material for a lithium-ion capacitor or a lithium-ion battery, compared to a porous body having a pore structure in which only one of mesopores or macropores is formed.

[0035] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art to which the present invention pertains from the description below. Brief explanation of the drawing

[0037] FIG. 1 is a flowchart illustrating a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a pore structure that can be formed in a polymer-derived ceramic according to an embodiment and a comparative example of the present invention. Figure 3 is a graph showing the results of the BET (Brunauer-Emmett-Teller) specific surface area analysis of a SiC porous body according to the amount of pitch added in a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention. Figure 4 is a Scanning Electron Microscope (SEM) image of a SiC porous body according to the first heat treatment temperature in a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention. Figure 5 is a graph showing the results of BET specific surface area analysis of a SiC porous body according to the secondary heat treatment temperature in a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention. Figure 6 is a cyclic voltammetry (CV) graph of a SiC porous body manufactured by a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the invention. Specific details for implementing the invention

[0038] In the present invention, the attached drawings may be illustrated with exaggerated expressions to distinguish it from the prior art, ensure clarity, and facilitate the understanding of the technology. Furthermore, the terms described below are defined considering their functions in the present invention; since these terms may vary depending on the intentions or conventions of the user or operator, their definitions should be based on the technical content throughout this specification. Meanwhile, the embodiments are merely exemplary details of the components presented in the claims of the present invention and do not limit the scope of the rights of the present invention; the scope of rights should be interpreted based on the technical concept throughout the specification of the present invention.

[0039] Throughout the specification, when a configuration is described as "including" a configuration, this means that, unless specifically stated otherwise, it does not exclude other configurations but may include additional configurations.

[0040] Furthermore, when it is said that one configuration is "connected," "connected," or "combined" with another configuration, this means that it is not only "directly connected," "directly connected," or "directly combined," but also that there may be cases where it is "connected with another configuration interposed," "connected with another configuration interposed," or "combined with another configuration interposed." On the other hand, when it is said that one configuration is "directly connected," "directly connected," or "directly combined" with another configuration, it should be understood that there is no other configuration in between.

[0041] In addition, when directional terms such as "front," "back," "up," "down," "left," "right," "first end," "other end," and "both ends" are used, they are used exemplarily in relation to the orientation of the disclosed drawings and should not be interpreted restrictively, and when terms such as "first" and "second" are used, they are terms used to distinguish each configuration and should not be interpreted restrictively.

[0042] In order to more clearly explain the features of the embodiments of the present invention, detailed descriptions of matters widely known to those skilled in the art to which the following embodiments pertain are omitted. Additionally, detailed descriptions of parts in the drawings that are unrelated to the description of the embodiments are omitted.

[0043] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0045] FIG. 1 is a flowchart illustrating a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention; FIG. 2 is a diagram schematically illustrating a pore structure that can be formed in a polymer-derived ceramic according to an embodiment and a comparative example of the present invention; FIG. 3 is a graph showing the results of BET (Brunauer-Emmett-Teller) specific surface area analysis of a SiC porous body according to the amount of pitch added in a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention; FIG. 4 is a Scanning Electron Microscope (SEM) image of a SiC porous body according to the first heat treatment temperature in a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention; FIG. 5 is a graph showing the results of BET specific surface area analysis of a SiC porous body according to the second heat treatment temperature in a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention; and FIG. 6 is a ceramic porous body for a lithium-ion capacitor having a controlled pore structure manufactured by a method according to an embodiment of the invention. This is the cyclic voltammetry (CV) graph of a SiC porous material.

[0047] Referring to FIG. 1, a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention comprises a solution forming step (S10), a first powder forming step (S20), a first heat treatment step (S40), and a second heat treatment step (S60). Additionally, a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention may further include an oxidation curing step (S30), a grinding step (S50), and a sieving step (S60).

[0049] In this specification, "ceramic porous body for lithium-ion capacitor having a controlled pore structure" may be used interchangeably with "ceramic porous body for LIC" or "ceramic porous body".

[0051] The above solution forming step (S10) is a step of forming a solution containing a ceramic precursor and a carbon precursor.

[0052] The ceramic precursor is a material that can be converted into ceramic by pyrolysis and is capable of forming macro to meso pores.

[0053] The above carbon precursor is a material that can be converted into carbon by pyrolysis and is a material that can form macropores (mseo~micro pores) in the meso.

[0054] Typically, macropores have a diameter of 50 nm or more, mesopores have a diameter of 2 to 50 nm, and micropores have a diameter of 2 nm or less.

[0055] In this embodiment, a ceramic porous body having a combination of meso and macro pores can be manufactured by using a mixture of the ceramic precursor and the carbon precursor, each capable of forming pores of different sizes. Specifically, according to this embodiment, by using a combination of the ceramic precursor and the carbon precursor and appropriately adjusting the heat treatment conditions, a ceramic porous body for a lithium-ion capacitor having a controlled pore structure in which macro pores are formed on the surface and meso pores are formed inside can be manufactured.

[0056] The above ceramic precursor can be appropriately selected depending on the ceramic porous body to be formed.

[0057] In one embodiment, when forming a SiC porous body, polycarbosilane ('PCS') may be used as the ceramic precursor.

[0058] In another embodiment, when forming a Si3N4 porous body, the ceramic precursor may be polysilazane.

[0059] In another embodiment, when forming a Si-NB porous body, polyborosilazane may be used as the ceramic precursor.

[0060] In another embodiment, when forming a SiO2 porous body, polysiloxane may be used as the ceramic precursor.

[0061] The above carbon precursor may include a material that can be converted into carbon by pyrolysis.

[0062] In one embodiment, the carbon precursor may include one or more selected from the group consisting of pitch, phenolic resin, cellulose, lignin, polyacrylonitrile ('PAN'), furfuryl alcohol resin, and xylene resin.

[0063] The above solution can be formed by first dissolving the ceramic precursor in a solvent to form a ceramic precursor solution, and then adding and dissolving the carbon precursor in the ceramic precursor solution.

[0064] The solvent used to form the ceramic precursor solution may be one or more selected from the group consisting of alcohol, toluene, xylene, cyclohexane, and combinations thereof.

[0065] The amount of the solvent in the ceramic precursor solution may be 1 to 4 times the weight of the ceramic precursor. If the amount of the solvent is less than the above range, the ceramic precursor may not be completely dissolved, and if it exceeds the above range, it is difficult to expect an increase in the dissolution effect with increasing the amount of the solvent.

[0066] The carbon precursor may be added to the ceramic precursor solution in a weight ratio of 30 to 70 percent relative to the ceramic precursor. If the amount of the carbon precursor is less than the above range, the specific surface area of ​​the formed ceramic porous body may be very low, and the formation of surface pores may be very insufficient; if it exceeds the above range, the pore size of the ceramic porous body may become too large, and the specific surface area may actually decrease.

[0067] Accordingly, according to an embodiment of the present invention, by optimizing the content of the ceramic precursor and the carbon precursor, the ceramic porous body formed can have a controlled composite pore structure formed with appropriate sizes and have a high specific surface area.

[0069] The above first powder forming step (S20) is a step of forming a first powder by drying the solution formed in the above solution forming step (S10).

[0070] The above primary powder represents a powder comprising the above ceramic precursor and the above carbon precursor.

[0071] In one embodiment, the first powder forming step may include drying the solution under vacuum for 18 to 30 hours.

[0072] At this time, drying is several to 10 -2 It can be performed under vacuum with a vacuum level in the torr range.

[0074] The oxidation curing step (S30) described above is a step for maintaining the shape of the ceramic precursor when it decomposes and is converted into a crystalline form during the pyrolysis process. That is, when pyrolysis is performed to convert it into a ceramic in a subsequent process, if the softening temperature and melting temperature of the ceramic precursor are reached, the ceramic precursor may melt again, fail to maintain its shape, and turn into a liquid state. In this embodiment, by performing the oxidation curing, the shape of the ceramic precursor can be fully maintained when it decomposes and is converted into a crystalline form in a subsequent process.

[0075] In addition to oxidation curing, electron beam (EB) curing and chemical vapor curing (CVC) are known curing methods.

[0076] The electron beam curing described above induces radical bonding between silicon atoms within the ceramic precursor structure using a powerful electron beam. Therefore, while this electron beam curing has the advantage of producing high-purity SiC fibers free of impurities, it has the disadvantage of requiring expensive electron beam irradiation equipment. The chemical vapor curing method described above utilizes various gases as crosslinking promoters and has the advantage of enabling rapid curing at lower temperatures compared to other curing methods; however, it has the disadvantage that the crosslinking promoters remain as impurities in the final silicon carbide fibers.

[0077] Accordingly, in this embodiment, oxidation curing is applied, which has advantages over other curing methods and no major disadvantages.

[0078] In one embodiment, the oxidation curing step (S30) can be performed by applying hot air at 150 to 200°C to the primary powder for 8 to 12 hours.

[0079] By the oxidation curing step (S30), oxygen atoms are inserted between the silicon and silicon of the ceramic precursor to act as a bridge, thereby preventing the ceramic precursor from swelling or melting during subsequent thermal decomposition, and thus the shape of the ceramic precursor can be maintained intact.

[0081] The above first heat treatment step (S40) is a step of converting the above first powder into a second powder by thermal decomposition. That is, through the above first heat treatment step (S40), the ceramic precursor and the carbon precursor can be converted into ceramic and carbon. At this time, macropores may be formed on the surface of the ceramic.

[0082] The above secondary powder represents a powder containing ceramic and carbon.

[0083] That is, in the first heat treatment step (S40), macropores may be formed on the surface of the ceramic porous body due to the thermal decomposition of the ceramic precursor. When the ceramic precursor is thermally decomposed, overgrowth occurs from the surface, so a significantly large number of pores may be formed on the surface, and in addition, by appropriately controlling the conditions of the first heat treatment step (S40), a large number of macropores may be left on the surface of the ceramic porous body.

[0084] In the first heat treatment step (S40) above, since the pore structure of the surface of the ceramic porous body may be formed differently depending on the conditions, the present embodiment is characterized by finely controlling the conditions of the first heat treatment step (S40) so that macropores can be uniformly formed on the surface of the ceramic porous body.

[0085] The first heat treatment step (S40) above may be performed at a temperature in the range of 1500 to 1600°C. If the temperature of the first heat treatment step (S40) is below the above range, it may be difficult to form sufficient macro-sized pores, and if it exceeds the above range, the surface of the ceramic porous body formed may be rough and the pore size may become excessively large.

[0086] The first heat treatment step (S40) may be performed for 10 minutes to 3 hours. If the time of the first heat treatment step (S40) is less than the above range, sufficient macro-sized pores may not be formed, and if it exceeds the above range, very non-uniform pores may be formed on the surface due to excessive grain growth or macro-sized pores may be formed inside, which may significantly reduce the strength of the ceramic porous body.

[0087] The above first heat treatment step (S40) can be performed under an inert atmosphere.

[0088] In this way, in the present embodiment, macropores can be uniformly formed on the surface of the ceramic porous body by appropriately adjusting the conditions of the heat treatment process in the first heat treatment step (S40).

[0090] The grinding and sieving step (S50) above is a step for pulverizing and finely grinding the secondary powder.

[0091] By performing the grinding and sieving step (S50) above, the heterogeneous secondary powder formed in the first heat treatment step (S40) can be homogenized, and a powder of a size smaller than a predetermined size can be obtained. Accordingly, the size of the secondary powder can be refined and homogenized, thereby allowing for fine control of the pore structure of the ceramic porous body formed.

[0092] In one embodiment, the grinding step (S50) may be performed by grinding the secondary powder using a ball mill for 20 to 30 hours.

[0093] In one embodiment, the sieving step (S60) may be performed using a standard sieve of 80 to 120 μm, preferably about 100 μm.

[0095] The above second heat treatment step (S60) is a step of removing carbon from the above second powder.

[0096] By performing the above second heat treatment step (S60), the carbon converted from the carbon precursor is oxidized and removed, and mesopores can be formed inside the ceramic porous body.

[0097] That is, in the second heat treatment step (S60), mesopores may be formed inside the ceramic porous body below the macropores on the surface of the ceramic porous body formed by the first pyrolysis due to the oxidation of carbon.

[0098] Since the oxidation resistance temperature of the ceramic porous body formed in the first heat treatment step (S40) is about 1000°C or higher, the macropores formed on the surface of the ceramic porous body in the second heat treatment step (S60) can be maintained without change.

[0099] Since the pore structure inside the ceramic porous body may be formed differently depending on the conditions of the second heat treatment step (S60), the present embodiment is characterized by finely controlling the conditions of the second heat treatment step (S60) so that mesopores can be uniformly formed inside the ceramic porous body.

[0100] The above second heat treatment step (S60) can be performed at a temperature in the range of 550 to 750°C. If the temperature of the above second heat treatment step (S60) is below the above range, carbon is not sufficiently removed, so the specific surface area of ​​the ceramic porous body formed may be very low, and if it exceeds the above range, an oxidation reaction occurs strongly, so the specific surface area of ​​the ceramic porous body formed may actually decrease.

[0101] The above second heat treatment step (S60) may be performed for 5 to 10 hours. If the time of the above second heat treatment step (S60) is less than the above range, the carbon may not be sufficiently oxidized, and thus mesopores may not be formed inside the ceramic porous body; if it exceeds the above range, the pore size becomes excessively large, and the specific surface area may actually decrease.

[0102] The above second heat treatment step (S60) can be performed in air.

[0103] Accordingly, according to an embodiment of the present invention, macropores are formed on the surface of the ceramic porous body through an overgrowth mechanism when the ceramic precursor is pyrolyzed and converted into ceramic by the first pyrolysis step (S40), and mesopores are formed inside the ceramic porous body below the macropores formed on the surface of the ceramic porous body by the oxidation of carbon by the second pyrolysis step (S60). At this time, the first pyrolysis step (S40) is performed under appropriately controlled conditions to form macropores on the surface of the ceramic porous body, and the second pyrolysis step (S60) can be performed under appropriately controlled conditions to form mesopores inside the ceramic porous body.

[0104] In this way, by forming a microstructure in which the surface macropores and internal mesopores are appropriately controlled, the ceramic porous body can have a high specific surface area and possess excellent ion storage / release capabilities. Furthermore, the ceramic porous body exhibits higher thermal and structural stability compared to conventional graphite materials, thereby preventing the problems of structural expansion and thermal instability associated with conventional graphite materials during charging and discharging.

[0106] According to the method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to an embodiment of the present invention, by using a combination of a ceramic precursor and a carbon precursor and optimizing two-stage heat treatment conditions, a ceramic porous body for a lithium-ion capacitor having a controlled pore structure can be manufactured, which has excellent ion storage and ion emission capabilities, high oxidation resistance, high heat resistance, and excellent structural stability, by forming macropores on the surface and mesopores inside.

[0107] The ceramic porous body produced by the method for producing a ceramic porous body according to an embodiment of the present invention has a pore structure appropriately controlled to satisfy the characteristics required in the field of application, and can be efficiently applied in a wide range of fields such as electrode materials for lithium-ion capacitors or lithium-ion batteries, catalysts, filters, thermal insulation materials, artificial biomaterials, lightweight structural materials, and shock absorbers.

[0108] In addition, the ceramic porous body produced by the method for producing a ceramic porous body according to an embodiment of the present invention can exhibit superior performance, particularly as an electrode material for a lithium-ion capacitor or a lithium-ion battery, compared to a porous body having a pore structure in which only one of mesopores or macropores is formed.

[0110] The present invention will be explained in more detail below through examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

[0112] [Example]

[0114] 1. Fabrication of a ceramic porous body for lithium-ion capacitors having a controlled pore structure

[0115] Polycarbosilane ('PCS') was dissolved in toluene at a weight ratio of 1:1 to form a PCS solution. Pitch was added to the PCS solution at weight ratios of 20%, 30%, 50%, 70%, and 80% relative to the PCS. The PCS-pitch solution was vacuumed (1×10⁻⁶ -1The powder was recovered by drying for 24 hours under torr. Oxidative curing was performed on the recovered PCS-pitch powder by blowing hot air at 150–200°C for 10 hours. The oxidatively cured PCS-pitch powder was converted into SiC-C powder by primary heat treatment at temperatures of 1400°C, 1500°C, 1600°C, 1700°C, and 1800°C under an argon atmosphere. Subsequently, the SiC-C powder was ground using a ball mill for 24 hours and then sieved using a standard sieve of 100 µm. The SiC-C powder with a particle size of 100 µm or less was subjected to secondary heat treatment in air at temperatures of 450°C, 550°C, 650°C, 750°C, and 850°C to oxidize carbon while simultaneously forming macropores.

[0117] 2. Characterization of ceramic porous materials for lithium-ion capacitors having a controlled pore structure

[0118] (1) Pore structure of SiC porous material

[0119] FIG. 2 schematically illustrates the pore structure of a porous body that can be formed by varying the detailed conditions in the manufacturing method of 1 above. Comparative Example 1 shows the pore structure of a porous body formed by the thermal decomposition of PCS alone without pitch, and Comparative Example 2 shows the pore structure of a porous body formed by the thermal decomposition of pitch alone without PCS. In FIG. 2, each pore structure is schematically illustrated, and its size and shape are for illustrative purposes only and may differ from the actual structure.

[0120] As shown in FIG. 2, according to an embodiment of the present invention, a composite pore structure was shown in which macropores were formed on the surface and mesopores were formed inside. On the other hand, in Comparative Example 1, only macropores were formed on the surface, and in Comparative Example 2, only mesopores were formed inside.

[0121] (2) Analysis of BET specific surface area of ​​SiC porous material according to pitch addition amount

[0122] The BET specific surface area of ​​the SiC porous body according to the amount of pitch added was analyzed, and the results are shown in Figure 3. The SiC used for analysis was manufactured according to the manufacturing method of 1 above, with a first heat treatment temperature of 1500℃ and a second heat treatment temperature of 550℃.

[0123] As shown in Figure 3, when the pitch addition amount is lower than 30%, the BET specific surface area of ​​the SiC porous body is very low, so pores may not be properly formed on the surface, and when it is higher than 70%, the pores become too large, resulting in a decrease in the specific surface area. When the pitch addition amount is 80%, the BET decreases, showing a numerical BET similar to that of an addition amount of 50–70%; however, it is judged that the structural condition deteriorated microstructurally as the pores became disordered or the pore walls collapsed.

[0124] (3) SEM analysis of SiC porous body according to primary heat treatment temperature

[0125] SEM images of the SiC porous body according to the first heat treatment temperature were analyzed, and the results are shown in Figure 4.

[0126] As shown in Figure 4, when the first heat treatment temperature was 1400°C, the surface of the SiC porous body was observed to be rough and have large pores, but at 1500°C and 1600°C, the surface became dense again due to crystal grain coarsening, and pores of several macro-sized were observed. Meanwhile, when the first heat treatment temperature was 1700°C and 1800°C, it was confirmed that powder particles of several tens of macro-sized were broken down into very small particles due to excessive decomposition.

[0127] Therefore, it was confirmed that when the first heat treatment temperature is in the range of 1500~1600℃, surface pores of the SiC porous body can be uniformly and appropriately formed at a macro size.

[0128] (4) Analysis of BET specific surface area of ​​SiC porous material according to secondary heat treatment temperature

[0129] The BET specific surface area of ​​the SiC porous body according to the second heat treatment temperature was analyzed, and the results are shown in Figure 5.

[0130] As shown in Figure 5, when the secondary heat treatment temperature was below 550°C, carbon was not removed, so the BET specific surface area of ​​the SiC porous body was very low, and when it exceeded 750°C, it was observed that the BET specific surface area of ​​the SiC porous body gradually decreased due to oxidation.

[0131] (5) Analysis of battery performance of SiC porous material

[0132] Figure 6 shows the results of the cyclic voltammetry (CV) analysis of SiC porous bodies having different pore structures formed according to the embodiments and comparative examples of the present invention.

[0133] The CV curve shows the efficiency and performance according to charging and discharging; the charging and discharging cycles must be constant, and the larger the area between the charge and discharge graphs, the higher the storage capacity can be.

[0134] As shown in FIG. 6, in the case of Comparative Example 1 having only a macropore structure and Comparative Example 2 having only a mesopore structure, it can be seen that the graph of the CV curve decreases as the charge-discharge cycle progresses. However, in the case of the SiC porous body according to the embodiment having a controlled pore structure in which surface macropores and internal mesopores are combined, it can be seen that the charge-discharge cycle is constant and the area between the charge-discharge graph is significantly large. Accordingly, the ceramic porous body according to the present invention can exhibit excellent performance for lithium-ion capacitors.

[0136] Thus, according to the method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to the present invention, by having a controlled pore structure in which macropores are formed on the surface and mesopores are formed inside, it is possible to provide a ceramic porous body for a lithium-ion capacitor having a controlled pore structure that possesses excellent ion storage and ion emission capabilities, as well as high oxidation resistance, high heat resistance, and excellent structural stability. Furthermore, the ceramic porous body manufactured by the method according to the present invention has an appropriately controlled pore structure to satisfy the characteristics required in the field of application, and can be efficiently applied in a wide range of fields such as electrode materials for lithium-ion capacitors or lithium-ion batteries, catalysts, filters, thermal insulation materials, artificial biomaterials, lightweight structural materials, and shock absorbers.

[0138] As described above, the present invention has been explained with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and it should be understood that various modifications and equivalent alternative embodiments are possible based on the ordinary knowledge of the art to which the art belongs. Accordingly, the true technical scope of protection of the present invention is defined by the claims described below and should be determined based on the specific details of the invention described above. Industrial applicability

[0140] The present invention relates to a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, and can be used in industrial fields related to electrode materials for lithium-ion capacitors or lithium-ion batteries, catalysts, filters, thermal insulation materials, artificial biomaterials, lightweight structural materials, and shock absorbers.

[0141] No content

Claims

Claim 1 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, comprising: a solution forming step of forming a solution containing a ceramic precursor, which is a polymer that can be converted into ceramic by pyrolysis, and a carbon precursor, which is a material that can be converted into carbon by pyrolysis; a first powder forming step of drying the solution to form a first powder; a first heat treatment step of converting the first powder into a second powder containing ceramic and carbon by pyrolysis; and a second heat treatment step of oxidizing the carbon of the second powder; wherein, by the first heat treatment step, macropores with a diameter of 50 nm or more are formed on the surface of the ceramic porous body, and by the second heat treatment step, mesopores with a diameter of 2 to 50 nm are formed inside the ceramic porous body as the carbon is oxidized and removed. Claim 2 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, wherein, in claim 1, the ceramic precursor is one or more selected from the group consisting of polycarbosilane ('PSC'), polysilazne, polyborosilazne, and polysiloxanes. Claim 3 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, wherein, in claim 1, the carbon precursor comprises a material that is converted into carbon by pyrolysis. Claim 4 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, characterized in that, in claim 1, the carbon precursor is added in a weight ratio of 30 to 70% relative to the ceramic precursor. Claim 5 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, wherein the first powder forming step comprises drying the solution under vacuum for 18 to 30 hours. Claim 6 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, characterized in that, in claim 1, after the first powder forming step, it further comprises the step of performing oxidation curing by applying hot air at 150 to 200°C to the first powder for 8 to 12 hours. Claim 7 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, wherein, in claim 1, the first heat treatment is performed at a temperature in the range of 1500 to 1600℃. Claim 8 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, characterized in that, in claim 1, after the first heat treatment step, the method further comprises a grinding step of grinding the second powder using a ball mill for 20 to 30 hours; and a sieving step. Claim 9 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, characterized in that, in claim 8, the sieving step is performed using a standard sieve of 80 to 120 μm. Claim 10 A method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure, wherein, in claim 1, the second heat treatment step is performed in air at a temperature in the range of 550 to 750°C. Claim 11 A ceramic porous body manufactured by a method for manufacturing a ceramic porous body for a lithium-ion capacitor having a controlled pore structure according to any one of claims 1 to 10. Claim 12 In claim 11, the ceramic porous body is characterized by being used as a material for a lithium-ion capacitor.

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