Patent Application
20250236976
This application claims the priority of Korean Patent Application No. 10-2024-0010739 filed on Jan. 24, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
The disclosure relates to an electrode, and more specifically, to an LSCFP-based electrode and a method for manufacturing the same.
Carbon dioxide (CO2) is one of the main causes of global warming, and is a greenhouse gas that is released into the atmosphere and causes global temperature rise and climate change. In order to reduce this and achieve carbon neutrality, countries around the world are strengthening international cooperation and promoting various measures and technology development such as CCUS (CO2 capture, storage, and conversion).
A solid oxide electrolysis cell (SOEC) for CO2 reduction is gaining attention as a key technology that can solve environmental problems and create economic value at the same time by converting CO2 into a marketable chemical substance (CO) through an electrochemical reaction.
Since the double bond between carbon and oxygen is very stable, the energy required for CO2 reduction is greater than the thermodynamic energy. Therefore, one of the main challenges of CO2 reduction is to increase energy efficiency. A CO2 electrolysis solid oxide electrolytic cell operates at high temperatures (650˜850° C.), which has the great advantage of increasing the CO2 electrochemical reduction reaction rate and thus increasing energy efficiency.
The CO2-solid oxide electrolytic cell is composed of a porous ceramic fuel electrode, an air electrode, and an electrolyte membrane located between the fuel electrode and the air electrode. The CO2 injected into the fuel electrode is reduced to CO and oxygen ions (O2-) by an externally applied current, and the oxygen ions move to the air electrode through the electrolyte to generate O2. The fuel electrode must have high catalytic activity to decompose the C—O double bond and resistance to carbon coking under high CO2 concentrations during the electrolysis of CO2. Here, rationally designing the microstructure of the electrode is very important for the efficient use and improvement of materials including catalytic activity.
Recently, interest in the development of nanostructured electrodes has been rapidly increasing. In particular, research on the development of 1D nanofiber-based electrodes is actively being conducted. Nanofibers have high porosity for easy gas diffusion, paths for ion and electron conduction, and a large area for increasing reaction sites. However, despite the various advantages provided by nanofibers, their practical applications are limited due to insufficient interfacial contact with the solid electrolyte surface.
Therefore, appropriate structural development is required to solve the contact problem between porous nanofiber electrodes and solid electrolytes.
To solve the above-described problems of related arts, an aspect of the disclosure is to provide a hybrid LSCFP-based electrode.
Another aspect of the disclosure is to provide a method for manufacturing a hybrid LSCFP-based electrode.
The aspect of the disclosure is not limited to that mentioned above, and other aspects not mentioned will be clearly understood by those skilled in the art from the description below.
An example of the disclosure provides a hybrid LSCFP-based electrode.
In an example of the disclosure, a hybrid LSCFP-based electrode may include: an electrode having porous pores formed between a plurality of nanofibers; and pulverized nanofibers positioned within the porous pores.
In addition, in an example of the disclosure, the nanofibers may include nanofibers represented by chemical formula 1:
La1-xSrxCo1-y-zFeyPdzO3-δ [Chemical formula 1]
In addition, in an example of the disclosure, the length of the pulverized nanofibers may include 500 nm to 1 μm.
In addition, in an example of the disclosure, the mass ratio of the plurality of nanofibers and the pulverized nanofibers may include 7:3 to 3:7.
In addition, in an example of the disclosure, nano metal particles containing cobalt (Co) may be positioned on the surface of the nanofibers.
Another example of the disclosure provides a method for manufacturing a hybrid LSCFP-based electrode.
In an example of the disclosure, a method for manufacturing a hybrid LSCFP-based electrode may include: manufacturing a nanofiber material by calcining nanofibers; manufacturing a pulverized nanofiber material by pulverizing a portion of the nanofiber material; manufacturing a mixture by mixing the nanofiber material and the pulverized nanofiber material; and manufacturing a nanofiber electrode by applying and sintering the mixture.
In addition, in an example of the disclosure, the nanofibers may include at least one selected from the group consisting of lanthanum (La), strontium (Sr), cobalt (Co), iron (Fe), and palladium (Pd).
In addition, in an example of the disclosure, the pulverizing scheme for the pulverized nanofiber material may include at least one from the group consisting of mortar and ball milling.
In addition, in an example of the disclosure, the mass ratio of the nanofiber material and the pulverized nanofiber material of the mixture may include 7:3 to 3:7.
In addition, in an example of the disclosure, in the manufacturing of the nanofiber material by calcining nanofibers, the calcining temperature may include 900° C. to 1100° C.
A hybrid LSCFP-based electrode according to an example of the disclosure may provide an effect of improving a contact area at a solid electrolyte interface by adding pulverized nanofibers.
In addition, by adapting a hybrid LSCFP-based electrode according to an example of the disclosure as a CO2 unit cell fuel electrode, an effect of providing a high-temperature CO2 electrolysis cell with high performance and high durability may be provided.
In addition, a method for manufacturing a hybrid LSCFP-based electrode according to an example of the disclosure may provide an effect of manufacturing a hybrid LSCFP-based electrode in a simple manner.
The effects of the disclosure are not limited to the effects described above, and should be understood to include all effects that are inferable from the configuration of the disclosure described in the detailed description or claims of the disclosure.
The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
Hereinafter, the disclosure will be described with reference to the accompanying drawings. However, the disclosure may be implemented in various different forms and, therefore, is not limited to the examples described herein. In order to clearly explain the disclosure in the drawings, portions unrelated to the description are omitted, and similar portions are given similar reference numerals throughout the specification.
Throughout the specification, when a portion is said to be “connected (linked, contacted, combined)” with another portion, this includes not only a case of being “directly connected” but also a case of being “indirectly connected” with another member in between. In addition, when a portion is said to “include” a certain component, this does not mean that other components are excluded, but that other components may be added, unless specifically stated to the contrary.
The terms used herein are merely used to describe specific examples and are not intended to limit the disclosure. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, it should be understood terms such as “include” or “have” are to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.
Hereinafter, examples of the disclosure will be described in detail with reference to the accompanying drawings.
Conventional nanofiber-based electrodes have had problems in practical applications due to insufficient interfacial contact with the solid electrolyte surface.
In order to solve this problem, the disclosure provides a hybrid LSCFP-based electrode with improved interfacial contact with the solid electrolyte surface and a method for manufacturing the same.
Hereinafter, the disclosure will be described with reference to the drawings presented in this specification. For reference, the drawings may be expressed in an exaggerated manner to explain the features of the disclosure. In this case, it is preferable to interpret them in light of the entire intent of this specification.
A hybrid LSCFP-based electrode according to an example of the disclosure will be described.
A hybrid LSCFP-based electrode according to an example of the disclosure may include: an electrode having porous pores formed between a plurality of nanofibers; and pulverized nanofiber¬ positioned within the porous pores.
The disclosure may include an electrode having porous pores formed between a plurality of nanofibers.
At this time, the nanofibers may include nanofibers represented by chemical formula 1.
La1-xSrxCo1-y-zFeyPdzO3-δ [Chemical formula 1]
At this time, if the atomic ratio of the x, y, z, and & of chemical formula 1 is out of the range, Pd may not be doped into the perovskite lattice, which is the parent, so that a secondary phase may be formed.
Meanwhile, in order to improve the catalytic activity of the CO2 reduction reaction of the hybrid LSCFP-based electrode, continuous heat treatment is performed on the nanofibers in H2 and CO2 atmospheres to manufacture the hybrid LSCFP-based electrode, and at this time, the nanofibers may maintain the perovskite structure during the continuous heat treatment process.
Specifically, during the continuous heat treatment, the structure of the nanofibers is first converted from the perovskite structure to the Ruddlesden-Popper (RP) structure, and then restored to the perovskite structure again, so that the perovskite structure may be maintained.
Meanwhile, as the continuous heat treatment process is performed, nano-metal particles including cobalt (Co) may be positioned on the surface of the nanofibers of the hybrid LSCFP-based electrode.
Specifically, through the heat treatment process in an H2 atmosphere, nano-scale Co—Fe nano-metal particles are formed on the surface of the nanofiber, and then, when the gas environment is changed to CO2 and the continuous heat treatment is performed, the Fe particles may re-enter the lattice and Co nano-metal particles may be positioned on the surface of the nanofibers.
The disclosure may include pulverized nanofibers positioned within the porous pores.
A surface area in contact with a solid electrolyte of the hybrid LSCFP-based electrode of the disclosure may be improved through the pulverized nanofibers, thereby solving the contact problem.
At this time, the length of the pulverized nanofibers may include 500 nm to 1 μm.
If the length of the pulverized nanofibers is less than 500 nm, a problem of reduced fiber-to-fiber connectivity may occur, and if the length of the pulverized nanofibers exceeds 1 μm, a problem of not expressing hybrid active characteristics may occur.
Meanwhile, the pulverized nanofibers may be positioned within the porous pores existing between the plurality of nanofibers, and at this time, the amount of the pulverized nanofibers positioned may vary depending on the size of the pores.
In addition, the efficiency of the hybrid LSCFP-based electrode according to an example of the disclosure may vary depending on the mass ratio of the nanofibers and the pulverized nanofibers.
Therefore, the mass ratio of the plurality of nanofibers and the pulverized nanofibers of the hybrid LSCFP-based electrode may include 7:3 to 3:7, and preferably 6:4 to 4:6.
At this time, if the mass ratio described above is out of range, the contact problem between the electrolyte and the electrode still exists, which may cause high interfacial resistance.
Conventional nanofiber-based electrodes could not be free from the problem of conducting actual applications due to insufficient interfacial contact with the solid electrolyte surface.
Therefore, the hybrid LSCFP-based electrode using the pulverized nanofibers according to an example of the disclosure may solve the problem of insufficient interfacial contact with the solid electrolyte surface, and hereinafter, a method for manufacturing a hybrid LSCFP-based electrode of the disclosure will be described.
A method for manufacturing a hybrid LSCFP-based electrode according to an example of the disclosure will be described.
Referring to
At this time, the nanofiber may include at least one from the group consisting of lanthanum (La), strontium (Sr), cobalt (Co), iron (Fe), and palladium (Pd).
At this time, in order to manufacture the nanofibers, a lanthanum precursor, a strontium precursor, a cobalt precursor, an iron precursor, and a palladium precursor may be prepared by mixing them with a nanofiber precursor and electrospinning them.
For example, the lanthanum precursor may include La(NO3)·36H2O, the strontium precursor may include Sr(NO3)2, the cobalt precursor may include Co(NO3)·26H2O, the iron precursor may include Fe(NO3)·39H2O, and the palladium precursor may include Pd(OCOCH3)2, wherein after dissolving the stoichiometric amount of the precursors in a dimethylformamide solvent, a polyvinylpyrrolidone polymer, which is a nanofiber precursor, is added to the solution to create a uniform LSCFP (polymer precursor solution) mixture solution, and electrospinning may be performed using the mixture solution.
At this time, in order to perform electrospinning, for example, the mixed solution is loaded into a plastic syringe, and then a high voltage of 16.5 kV to 18.5 kV is applied to perform electrospinning at a rate of 0.2 ml/h to 0.3 ml/h, and through this, nanofibers may be manufactured.
Specifically, the nanofibers manufactured by performing the electrospinning may include, for example, nanofibers expressed by chemical formula 1.
La1-xSrxCo1-y-zFeyPdzO3-δ [Chemical formula 1]
Meanwhile, depending on the time and temperature of the calcination process, the characteristics of the manufactured nanofibers may change, which may cause changes in the properties of the manufactured electrode.
Therefore, the time and temperature of the calcination process may be important, and at this time, the preferable calcination temperature may include 900° C. to 1100° C.
At this time, if the calcination temperature is less than 900° C., the perovskite crystal structure of the nanofibers may not be properly formed, and if the calcination temperature exceeds 1100° C., there may be problems in which the thickness of the nanofibers increases and the crystal structure collapses.
In addition, the preferable time of the calcination process may include, for example, 1 hour to 3 hours.
Meanwhile, in order to improve the catalytic activity of the CO2 reduction reaction of the nanofibers, an additional heat treatment process may be performed on the nanofiber material.
For example, the nanofiber material may be first heat-treated in an H2 environment and then continuously heat-treated in a CO2 environment to position Co nanometal on the surface of the nanofiber, and the Co nanometal may act as a catalyst for the CO2 reduction reaction.
At this time, the preferable temperature of the heat treatment process in the H2 environment may be 650° C. to 750° C. for 1 hour to 5 hours.
In addition, the preferable temperature of the heat treatment process in the CO2 environment may be 650° C. to 850° C. for 30 minutes to 5 hours.
At this time, if the temperature and time range of the continuous heat treatment process described above are exceeded, there may be a problem in which a change in the crystal structure occurs however, if the catalytic activity of the CO2 reduction reaction of the nanofibers is improved, the conditions are not limited to the temperature and time range described above.
The pulverizing scheme for the pulverized nanofiber material may include at least one from the group consisting of mortar and ball milling, and preferably, pulverization may be performed using mortar.
At this time, in order to mix the above nanofiber material and the above pulverized nanofiber material, for example, a paste mixer capable of simultaneously rotating and rotating using a centrifugal acceleration of 400G or more may be used for mixing; however, any method capable of pulverizing while maintaining the characteristics of the nanofibers may be used without being limited to the group of methods described above.
The mass ratio of the nanofiber material and the pulverized nanofiber material of the mixture may include 7:3 to 3:7.
At this time, if the mass ratio described above is out of range, the contact problem between the electrolyte and the electrode still exists, which may cause high interfacial resistance.
Therefore, the mass ratio of the nanofiber material and the pulverized nanofiber material may be 7:3 to 3:7, and a more preferable mass ratio may be 6:4 to 4:6.
At this time, the manufactured nanofiber electrode may be a hybrid LSCFP-based electrode.
At this time, the sintering process may be performed in a temperature range capable of manufacturing the nanofiber electrode, and preferably, the temperature of the sintering process may include 900° C. to 1100° C.
At this time, if the temperature of the sintering process is less than 900° C., contact between the electrolyte and the electrode interface may not be sufficient, resulting in high interface resistance and delamination problems, and if the temperature of the sintering process exceeds 1100° C., agglomeration of the electrode structure or secondary phases or unwanted phases in the crystal structure may occur.
Meanwhile, the preferable thickness of the manufactured nanofiber electrode may be 15 μm to 25 μm.
At this time, if the thickness of the manufactured nanofiber electrode is less than 15 μm, problems such as reduction in mechanical strength and reaction surface area may occur, and if it exceeds 25 μm, problems such as restriction in smooth supply and discharge of reactants and products may occur.
The hybrid LSCFP-based electrode of the disclosure may provide a high-performance/high-stability effect for CO2 reduction at high temperatures, and to this end, has the advantage of providing an effect of solving the contact problem by improving the contact surface area at the solid electrolyte interface.
Therefore, the following will describe examples, comparative examples, and experimental examples of the disclosure having the aforementioned advantages.
Hereinafter, the disclosure will be described in more detail through examples, comparative examples, and experimental examples. These examples, comparative examples, and experimental examples are only intended to illustrate the disclosure, and the scope of the disclosure is not limited by these examples, comparative examples, and experimental examples.
Referring to
Thereafter, the mixture solution was loaded into a plastic syringe, and electrospinning was performed at a rate of 0.25 ml/h by applying a high voltage of 17.5 kV to produce nanofibers.
Referring to
Thereafter, in order to manufacture a hybrid (H-LSCFP) electrode, some of the black fiber material was pulverized with mortar to obtain a pulverized LSCFP nanofiber material.
Next, an unpulverized LSCFP nanofiber material was dispersed by ultrasonication, and the pulverized LSCFP nanofiber material and the dispersed LSCFP nanofiber material were mixed with a binder (441 ESL, Electro Science) to obtain H-LSCFP Ink.
Finally, the H-LSCFP Ink Volume=Area 0.5 cm2 (or 5×107 μm2)×height (−18 μm)=9×108 μm3 was applied and sintered to manufacture an electrode.
At this time, the sintering temperature was 1100° C. and the time was 3 hours.
Thus, a hybrid (H-LSCFP) electrode was manufactured.
First, to fabricate a half-cell, (Sr, Mg)-doped LaGaO3 (LSGM) powder was placed in a mold and uniaxial pressing was used.
At this time, a pressure of 50 MPa was applied and sintered at 1400° C. for 5 hours to fabricate an LSGM pellet.
Thereafter, to fabricate a unit cell, the air electrode and fuel electrode, which are hybrid LSCFP nanofiber electrodes (H-LSCFP) fabricated previously, were laminated on both sides of the previously fabricated LSGM pellet and sintered simultaneously at 1100° C. for 3 hours.
Thus, a unit cell including a hybrid LSCFP-based electrode was fabricated.
The same process as in the example was performed, but to manufacture the 100% nanofiber electrode (F-LSCFP), only LSCFP nanofibers were dispersed by ultrasonication and mixed with a binder (441 ESL, Electro Science) to manufacture F-LSCFP Ink, which was then used to manufacture an electrode.
Thus, a 100% nanofiber electrode (F-LSCFP) was manufactured.
The same process as in the example was performed, but the previously manufactured 100% nanofiber electrode (F-LSCFP) was used.
Thus, a unit cell including a 100% nanofiber electrode was manufactured.
The crystallographic phase of the nanofibers manufactured according to the example was analyzed.
At this time, Cu K powder XRD measurement was performed using an X-ray diffractometer (RIGAKU, SmartLab) in the 20 range of 20° to 80° with Cu Kα radiation (2=1.5418 Å), and nanofiber XRD measurement was performed. The crystal structure of the nanofiber was analyzed using HighScore software.
Referring to
This may mean that when the manufactured LSCFP nanofibers are calcined at 1000° C. for 2 hours, a pure Trigonal (Hexagonal-setting) perovskite structure is formed without secondary phases or impurities.
Referring to
Referring to
From the HR-TEM analysis results in
In addition, as can be seen in
Referring to
The HR-TEM analysis results in
The half-cell and unit cell including the hybrid LSCFP-based electrode (H-LSCFP) manufactured according to the example and the electrode manufactured with 100% nanofibers in the past (F-LSCFP) were evaluated.
At this time, the microstructural analysis of the unit cell was performed using scanning electron microscopy (SEM, Hitachi SU8230).
In addition, the electrochemical characteristics of the half-cell and single cell were evaluated using a potentionstat (Bio-Logic, VMP-300), wherein CO2 was injected into the fuel electrode of the half-cell and single cell, and air was injected into the air electrode.
Referring to
As shown in
For example, as shown in
This may mean that the catalytic activity is high.
In addition, as shown in
As shown in
As shown in
As shown in
As shown in
As shown
Through the experimental example described above, it is possible to confirm that a battery to which the hybrid LSCFP-based electrode of the disclosure, H-LSCFP, is applied has lower electrical resistance and reduced activation energy compared to a battery to which the 100% nanofiber electrode, F-LSCFP, is applied, and that the former also has excellent electrolytic performance at high temperatures and excellent stability.
The description of the disclosure described above is for illustrative purposes, and those skilled in the art will understand that the disclosure is easily modifiable into other specific forms without changing the technical idea or essential features of the disclosure. Therefore, the examples described above should be understood in all respects as illustrative and not restrictive.
For example, each component described as single may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form. The scope of the disclosure is indicated by the claims described below, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2024-0010739 | Jan 2024 | KR | national |
