Transition metal sulfide nanoparticle / mxene composite, manufacturing method thereof, anode material and supercapacitor containing the same

Abstract

One embodiment of the present invention provides a Co-Fe-S / MXene composite comprising MXene and nanoparticles composed of cobalt, iron, and sulfur, and a method for manufacturing the same. When the Co-Fe-S / MXene composite according to one embodiment of the present invention is used as a negative electrode material for an asymmetric supercapacitor, it can provide a supercapacitor having high energy density, high power output, and long lifespan characteristics.

Description

Technology Field

[0001] The present invention relates to a nanoparticle / MXene composite, and more specifically, to a transition metal sulfide nanoparticle / MXene composite that can be used as a negative electrode material for a supercapacitor. Background Technology

[0002] Supercapacitors, characterized by high output and long lifespan, are used as primary or auxiliary power sources for small electronic devices, EVs, and powertrains. However, the low energy density of supercapacitors fails to meet the energy requirements of the modern electronics industry, resulting in relatively limited applications. To overcome this problem, research is being conducted to improve the energy density of supercapacitors.

[0003] Research on asymmetric supercapacitors is being conducted as one method to increase energy density. The energy density of a supercapacitor is proportional to V (cell voltage). In the case of commercial supercapacitors, there is a limit to increasing the cell voltage because the same material is used as the active material for both the positive and negative electrodes. On the other hand, asymmetric supercapacitors, which use different types of active materials for the positive and negative electrodes, can achieve high cell voltages due to the different electrochemical potential ranges of the negative and positive electrode materials.

[0004] The performance of asymmetric supercapacitors is significantly influenced by the individual electrochemical properties of the cathode and anode electrode materials. Therefore, the development of electrode materials with high capacity, high power output, and long lifespan characteristics is essential. According to technical literature reported to date, considerable effort has been devoted to developing anode electrode materials that exhibit superior performance in asymmetric supercapacitors. However, research and development on cathode materials has been conducted at a relatively low frequency, and EDLC-type carbon materials are still being used as cathode materials for asymmetric supercapacitors. These carbon materials cannot store large amounts of charge due to their charge storage mechanism based on electrochemical adsorption. Consequently, research is underway to replace existing EDLC-type electrode materials with pseudocapacitor-type materials capable of exhibiting high capacitance through surface oxidation / reduction reactions.

[0005] MXene, a two-dimensional material, is attracting attention as one of the candidates to replace EDLC-type cathode materials. MXene exhibits excellent electrochemical properties due to its superior electrical conductivity, high chemical stability, and numerous oxidation / reduction active sites. Furthermore, the presence of surface functional groups such as -F, -O, and -OH on MXene sheets enhances their hydrophilicity, thereby enabling the preparation of uniform MXene dispersions. This facilitates various solution synthesis methods, such as vacuum filtration, freeze-drying, hydrothermal synthesis, and spin coating. Despite these advantages, the capacity of electrodes containing MXene fails to meet the energy standards required by the current electronics industry, limiting their application on a commercial scale.

[0006] To address this, numerous studies have been conducted on the fabrication of composites of MXene with EDLC-type materials such as graphene, carbon nanotubes, or graphene oxide. While these composites have improved the charge storage capacity of MXene-based electrodes to a certain extent, no composites with a capacity of 400-500 F g or more have been reported due to the low charge storage capacity of EDLC-type materials. Prior art literature

[0007] Chinese Public Patent 114088787 A The problem to be solved

[0008] The present invention aims to provide a negative electrode material for an asymmetric supercapacitor having high energy density, high power output, and long lifespan characteristics, and an asymmetric supercapacitor including the same, as a method to solve the problems of the aforementioned prior art.

[0009] Specifically, by manufacturing an OD / 2D composite based on a 2D MXene material with high power characteristics and providing additional active sites, and thereby increasing the charge storage capacity of the material, it became possible to develop a Co-Fe-S / MXene composite, which is an energy storage material exhibiting high charge storage capacity.

[0010] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0011] To achieve the above technical objectives, one embodiment of the present invention provides a Co-Fe-S / MXene complex.

[0012] A Co-Fe-S / MXene composite according to one embodiment of the present invention is characterized by comprising: MXene; and nanoparticles bonded to a sheet of said MXene and comprising cobalt (Co), iron (Fe), and sulfur (S).

[0013] In an embodiment of the present invention, the nanoparticle may be characterized as a binary transition metal sulfide nanoparticle composed of cobalt sulfide and iron sulfide.

[0014] In an embodiment of the present invention, the cobalt sulfide is represented as Co4S3, and the iron sulfide is Fe9S 11 It can be characterized by being represented as.

[0015] To achieve the above technical objectives, one embodiment of the present invention provides a method for manufacturing a Co-Fe-S / MXene composite.

[0016] A method for preparing a Co-Fe-S / MXene composite according to an embodiment of the present invention comprises: a first step of preparing a MXene dispersion; a second step of preparing a Co-Fe layered double hydroxide (LDH) / MXene composite by adding a hydrate containing cobalt (Co) and a hydrate containing iron (Fe) to the MXene dispersion; and a third step of preparing a Co-Fe-S / MXene composite by adding a hydrate containing sulfur (S) to the Co-Fe layered double hydroxide / MXene composite.

[0017] In an embodiment of the present invention, the first step may be a method for manufacturing a negative electrode material for a Co-Fe-S / MXene composite asymmetric supercapacitor, characterized by preparing a MXene dispersion using sonication.

[0018] In an embodiment of the present invention, the method for manufacturing a Co-Fe-S / MXene composite may be characterized in that the hydrate containing cobalt in the second step is Co(NO3)2·6H2O and the hydrate containing iron is Fe(NO3)2·4H2O.

[0019] In an embodiment of the present invention, the second step may be a method for preparing a Co-Fe-S / MXene composite characterized by further adding urea and ammonia fluoride.

[0020] In an embodiment of the present invention, the second step may be a method for manufacturing a Co-Fe-S / MXene composite, characterized by manufacturing a Co-Fe double-layer hydroxide / MXene composite through a hydrothermal synthesis method.

[0021] In an embodiment of the present invention, the hydrothermal synthesis method may be a method for manufacturing a Co-Fe-S / MXene composite characterized by being performed at 150°C to 200°C.

[0022] In an embodiment of the present invention, the method for preparing a Co-Fe-S / MXene complex may be characterized in that the sulfur-containing hydrate of the third step is Na2S·9H2O.

[0023] In an embodiment of the present invention, the third step may be a method for manufacturing a Co-Fe-S / MXene composite, characterized by manufacturing the Co-Fe-S / MXene composite through a hydrothermal synthesis method.

[0024] In an embodiment of the present invention, the hydrothermal synthesis method may be a method for manufacturing a Co-Fe-S / MXene composite characterized by being performed at 100°C to 140°C.

[0025] In an embodiment of the present invention, the Co-Fe-S / MXene composite may be manufactured by the manufacturing method described above.

[0026] A cathode material according to one embodiment of the present invention may be characterized by including the Co-Fe-S / MXene complex.

[0027] An asymmetric supercapacitor according to one embodiment of the present invention may be characterized by including a cathode composed of the above-mentioned cathode material. Effects of the invention

[0028] According to an embodiment of the present invention, high rate capability and storage capacity can be exhibited due to the excellent output characteristics of the MXene material and additional active sites of the introduced Co-Fe-S nanoparticles. In addition, when the cathode material according to an embodiment of the present invention is applied as a cathode, it is possible to provide an asymmetric supercapacitor having high energy density, high output, and long lifespan characteristics.

[0029] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims. Brief explanation of the drawing

[0030] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a Co-Fe-S / MXene composite according to one embodiment of the present invention. Figure 2 is an FESEM image of a Co-Fe-S / MXene complex according to one embodiment of the present invention. FIG. 3 is a graph showing the XPS spectrum of a Co-Fe-S / MXene composite according to one embodiment of the present invention. ((a) Co 2p, (b) Fe 2p, (c) S 2p, (d) Ti 2p, (e) C 1s) Figure 4 is a graph showing the electrochemical performance of an electrode containing a Co-Fe-S / MXene composite as a cathode material according to one embodiment of the present invention. Figure 4-(a) shows the CV graph of an electrode containing MXene, Co-Fe-LDH / MXene or Co-Fe-S / MXene. Figure 4-(b) shows the GCD graph of an electrode containing MXene, Co-Fe-LDH / MXene or Co-Fe-S / MXene. Figure 4-(c) shows the Nyquist plot of an electrode containing Co-Fe-LDH / MXene or Co-Fe-S / MXene. Figure 4-(d) shows the CV graph according to the voltage scan rate of an electrode containing Co-Fe-S / MXene. Figure 4-(e) shows a graph of GCD according to the change in current density of an electrode containing Co-Fe-S / MXene. Figure 4-(f) shows the capacitance according to current density of an electrode containing Co-Fe-LDH / MXene or Co-Fe-S / MXene. Figure 4-(g) is a graph showing the results of the lifetime stability evaluation of an electrode containing Co-Fe-S / MXene. Figure 4-(h) is a graph showing the EIS comparison results before and after charging and discharging of an electrode containing Co-Fe-S / MXene. Figure 5 is a graph showing the XRD analysis results of a Co-Fe-S / MXene complex according to one embodiment of the present invention. Specific details for implementing the invention

[0031] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0032] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0033] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0034] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0036] A Co-Fe-S / MXene complex according to one embodiment of the present invention is described.

[0037] A Co-Fe-S / MXene composite according to one embodiment of the present invention is characterized by comprising: MXene; and nanoparticles bonded to a sheet of said MXene and comprising cobalt (Co), iron (Fe), and sulfur (S).

[0038] In an embodiment of the present invention, the MXene may satisfy the following chemical formula 1 as a transition metal carbide, transition metal nitride, or transition metal carbonitride having two-dimensional crystallinity.

[0039] (Chemical Formula 1)

[0040] M n+1 X n

[0041] In Chemical Formula 1, M is a transition metal selected from one or more of groups IIIB, IVB, VB, VIB, and VIIB, X is carbon (C), nitrogen (N), or a combination thereof, and n is 1, 2, or 3.

[0042] In one embodiment, the transition metal M may be titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), chromium (Cr), manganese (Mn), scandium (Sc), molybdenum (Mo), niobium (Nb), tantalum (Ta), yttrium (Y), tungsten (W), or a combination thereof, but is not limited thereto. X may be carbon, nitrogen, or carbon and nitrogen, and in one embodiment may be carbon. n may be 1, 2, or 3.

[0043] Representative examples of such MXenes include Ti2C, Ti2N, Ti3C2, Ti3N2, Ti3CN, Ti4N3, Nb4C3, Nb2C, Nb2N, V2C, V2N, Ta4C3, Mo2C, Mo2TiC2, Mo2Ti2C3, Cr2TiC2, (Ti0.5, Nb0.5)2C, Zr3C2, Hf3C2, Mo2TiC2, Cr2TiC2, or combinations thereof, but are not limited thereto.

[0044] In an embodiment of the present invention, the nanoparticles may be characterized as binary transition metal sulfide nanoparticles composed of cobalt sulfide and iron sulfide. In this case, the cobalt sulfide may be, for example, Co4S3, and the iron sulfide may be, for example, Fe9S 11 It may be, but is not limited to this.

[0046] A method for manufacturing a Co-Fe-S / MXene composite according to one embodiment of the present invention is described.

[0047] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a Co-Fe-S / MXene composite according to one embodiment of the present invention.

[0048] A method for preparing a Co-Fe-S / MXene composite according to an embodiment of the present invention comprises, as illustrated in FIG. 1, a first step (S100) of preparing a MXene dispersion; a second step (S200) of preparing a Co-Fe layered double hydroxide (LDH) / MXene composite by adding a hydrate containing cobalt (Co) and a hydrate containing iron (Fe) to the MXene dispersion; and a third step (S300) of preparing a Co-Fe-S / MXene composite by adding a hydrate containing sulfur (S) to the Co-Fe layered double hydroxide / MXene composite.

[0049] In the above manufacturing method, the first step (S100) is the step of preparing a MXene dispersion.

[0050] In the above steps, the MXene is as described above. In such MXene, the flakes of a two-dimensional transition metal carbide, transition metal nitride, or transition metal carbonitride can be terminated by a surface functional group collectively referred to as Tx. As is well known, the MXene with the surface functional group can be represented as Mn+1XnTx, and the surface functional group (Tx) may include alkoxides, carboxylates, halides, hydroxides, hydrides, oxides, nitrides, sulfides, thiols, or combinations thereof.

[0051] The presence of surface functional groups in the aforementioned MXene sheet enhances the hydrophilicity of the MXene sheet and consequently enables the preparation of a uniform dispersion, thereby facilitating various solution synthesis methods such as vacuum filtration, freeze-drying, hydrothermal synthesis, and spin coating.

[0052] At this time, as a means for preparing the above-mentioned MXene dispersion, sonication using ultrasound can be performed, for example, and specifically, it may be a method of adding MXene to distilled water and then proceeding with the sonication until a uniform dispersion is formed.

[0054] In the above manufacturing method, the second step (S200) is a step of preparing a Co-Fe layered double hydroxide (LDH, Layered Double Hydroxide) / MXene complex by adding a hydrate containing cobalt (Co) and a hydrate containing iron (Fe) to the MXene dispersion prepared in the first step (S100).

[0055] In this context, the Co-Fe double-layer hydroxide refers to a metal double-layer hydroxide with a double-layer structure containing cobalt metal ions and iron metal ions. Additionally, the Co-Fe double-layer hydroxide / MXene complex refers to a material in which a Co-Fe double-layer hydroxide is bonded to the surface of MXene. Hereinafter, “Co-Fe LDH” refers to a double-layer hydroxide in which Co and Fe are bonded, and “Co-Fe LDH / MXene” refers to a Co-Fe double-layer hydroxide / MXene complex.

[0056] At this time, the hydrate containing the above cobalt (Co) may preferably be a cobalt compound containing nitrate as a precursor for manufacturing the above-mentioned Co-Fe LDH, and may be, for example, Co(NO3)2·6H2O.

[0057] In addition, the hydrate containing iron (Fe) may preferably be an iron compound containing nitrate as a precursor for preparing the above-mentioned Co-Fe LDH, and may be, for example, Fe(NO3)2·4H2O.

[0058] In addition, in the second step (S200) above, it is preferable to further add urea and ammonia fluoride to the hydrate containing cobalt and the hydrate containing iron described above.

[0059] At this time, it may be preferable to perform the above second step through a hydrothermal synthesis method. The above hydrothermal synthesis method refers to a material synthesis method in which crystals are produced by heating a precursor and water under high pressure. At this time, an autoclave may be used as a means to implement the above hydrothermal synthesis method.

[0060] At this time, when performing the hydrothermal synthesis of the second stage above, the temperature may be 150℃ to 200℃, and preferably 180℃.

[0062] In the above manufacturing method, the third step (S300) is a step of preparing a Co-Fe-S / MXene complex by adding a sulfur-containing hydrate to the Co-Fe LDH / MXene complex prepared in the second step (S200).

[0063] In this case, the hydrate containing sulfur may be, for example, Na2S·9H2O.

[0064] At this time, the third step may preferably be performed through a hydrothermal synthesis method, and the temperature may be 100°C to 140°C, and preferably 120°C.

[0065] In the third step above, as a hydrate containing sulfur is added to the Co-Fe LDH structure, OH groups within the LDH structure may be substituted with sulfur, thereby causing a change in the previously known Co-Fe LDH structure and a change in the crystal structure. In addition, the Co-Fe-S / MXene composite prepared by this process forms a multi-phase structure of cobalt-based sulfides and iron-based sulfides, and has a crystal structure different from the existing Co-Fe LDH.

[0066] One embodiment of the present invention may be a Co-Fe-S / MXene composite prepared by the above-described manufacturing method.

[0067] A cathode material according to one embodiment of the present invention may be characterized by including the Co-Fe-S / MXene complex.

[0068] An asymmetric supercapacitor according to one embodiment of the present invention may be characterized by including a cathode composed of the above-mentioned cathode material.

[0070] The present invention will be explained in more detail below through manufacturing examples, comparative examples, and experimental examples. However, the present invention is not limited to the following manufacturing examples and experimental examples.

[0072] [Preparation Example 1] Preparation of Co-Fe-S / MXene Complex

[0073] Step 1: Preparation of MXene dispersion

[0074] Ti3C2T in 60 mL of distilled water x After adding 1g of MXene powder, sonication was carried out at room temperature for 2 hours until a uniform dispersion was formed.

[0075] Step 2: Preparation of Co-Fe LDH / MXene Complex

[0076] 0.2 g of Co(NO3)2·6H2O (1 mmol), 0.8 g of Fe(NO3)2·4H2O (2 mmol), 0.45 g of urea (7.5 mmol), and 0.11 g of ammonia fluoride (3 mmol) were added to the prepared dispersion and stirred for 25 minutes. The uniformly dissolved mixture was transferred to an 80 ml Teflon liner, and hydrothermal synthesis was carried out for 24 hours while maintaining a temperature of 180 °C. The prepared Co-Fe LDH / MXene complex was dispersed in distilled water and centrifuged three times, followed by washing using ethanol, repeating the same process three times. The sample was recovered by drying under vacuum at 60 °C.

[0077] Step 3: Preparation of Co-Fe-S@Mxene complex

[0078] 60 mL of distilled water, a sufficiently dried Co-Fe LDH / MXene complex, and Na2S·9H2O were added to an 80 mL Teflon liner, and hydrothermal synthesis was carried out at a temperature of 120°C for the time required for the reaction. Afterward, the Co-Fe-S / MXene complex powder was recovered through washing and drying processes.

[0080] [Preparation Example 2]: Preparation of an electrode comprising a Co-Fe-S / MXene complex

[0081] The Co-Fe-S / Mxene composite prepared in Preparation Example 1 above was mixed with conductive carbon powder and poly(vinylidene fluoride) (PVDF) binder in a mass ratio of 8:1:1. A suitable amount of this mixed powder was added to NMP, and sonication was performed for 30 minutes to prepare a uniform slurry. The prepared slurry was coated onto 3D Ni foam to manufacture an electrode.

[0083] [Preparation Example 3]: Preparation of a 3-electrode cell for evaluating the ion storage performance of a Co-Fe-S / MXene complex

[0084] A three-electrode cell was manufactured using the electrode prepared in Manufacturing Example 2 above as the working electrode, an Hg / HgO electrode as the reference electrode, and a Pt foil as the counter electrode.

[0086] Experimental Example 1: Morphoplogy Analysis of Co-Fe-S / MXene Complex

[0087] FIG. 2 is an FESEM image of a Co-Fe-S / MXene complex according to one embodiment of the present invention.

[0088] Morphological analysis of the composite prepared in Preparation Example 1 was performed. As shown in Fig. 2, observation using a scanning electron microscope (SEM) revealed that Co-Fe-S nanoparticles with an average size of 20 nm were evenly distributed on the MXene sheet.

[0090] Experimental Example 2: Chemical Structure Analysis of Co-Fe-S / MXene Complex

[0091] FIG. 3 is a graph showing the XPS spectrum of a Co-Fe-S / MXene composite according to one embodiment of the present invention. ((a) Co 2p, (b) Fe 2p, (c) S 2p, (d) Ti 2p, (e) C 1s)

[0092] XPS analysis was performed to analyze the chemical structure of the Co-Fe-S / MXene complex. Characteristic peaks of Co, Co, Co, and Co were observed in the Co 2p spectrum at 780.40, 782.08, 796.28, and 798.12 eV. As shown in Fig. 3(a), two peaks located at 786.12 and 802.29 eV represent satellite signals associated with the Co 2p spectrum. Fig. 3(b) shows the XPS spectrum of the Fe element, where two prominent peaks were observed: Fe 2p (710.88 eV) and Fe 2p (724.3 eV). Additionally, satellite peaks were observed at binding energies of 718.52 eV and 733.40 eV. Figure 3(c) shows the high-resolution XPS spectrum of S 2p, where the peaks at 160.90 eV and 162.92 eV are associated with S 2p and S 2p, respectively. The prominent peaks at 166.61, 168.30, and 169.55 eV correspond to the sulfate group, which implies the formation of Co-Fe-S nanoparticles. Figure 3(d) shows the high-resolution XPS spectrum of Ti, where two prominent peaks were observed: Ti 2p (458.30 eV) and Ti 2p (464.02 eV). Additionally, the peaks appearing at 458.24, 459.36, and 461.25 eV are associated with Ti, Ti-F, and Ti, respectively. Figure 3(e) shows the high-resolution XPS spectrum of C 1s, and the peaks at 284.6, 286.05, and 288.44 (eV) correspond to CC, CO, and OC=O bonds, respectively.

[0094] Experimental Example 3: Analysis of Energy Storage Characteristics of Co-Fe-S / MXene Composite Electrode

[0095] Figure 4 is a graph showing the electrochemical performance of an electrode containing a Co-Fe-S / MXene composite as a cathode material according to one embodiment of the present invention.

[0096] Figure 4-(a) shows the CV graph of an electrode containing MXene, Co-Fe-LDH / MXene or Co-Fe-S / MXene.

[0097] Electrochemical analysis was performed to analyze the energy storage characteristics of the Co-Fe-S / MXene composite. First, to evaluate the superiority of the Co-Fe-S / MXene composite, a performance comparison was conducted with MXene and Co-Fe-LDH / MXene composites. In the CV graph of Fig. 4-(a) above, among the three samples, the Co-Fe-S / MXene composite showed the most distinct redox peak and the largest capacitance.

[0098] Figure 4-(b) shows the GCD graph of an electrode containing MXene, Co-Fe-LDH / MXene or Co-Fe-S / MXene.

[0099] In the GCD graph of Fig. 4-(b), it was confirmed that the Co-Fe-S@MXene composite exhibited the highest discharge capacity. This is a result of the improved energy storage capacity due to the well-controlled size of the Co-Fe-S nanoparticles and the resulting increase in surface redox active sites.

[0100] Figure 4-(c) shows the Nyquist plot of an electrode containing Co-Fe-LDH / MXene or Co-Fe-S / MXene.

[0101] The improved electrochemical performance of the Co-Fe-S / MXene composite can also be confirmed in the EIS results. As can be seen in Figure 4-(c), it can be confirmed that Co-Fe-S / MXene has smaller Rs and Rct values ​​than Co-Fe-LDH / MXene.

[0102] Figure 4-(d) shows a CV graph according to the voltage scan rate of an electrode containing Co-Fe-S / MXene. Figure 4-(e) shows a GCD graph according to the change in current density of an electrode containing Co-Fe-S / MXene. Figure 4-(f) shows the capacitance according to the current density of an electrode containing Co-Fe-LDH / MXene or Co-Fe-S / MXene.

[0103] In Figures 4-(c) and 4-(d), the electrochemical behavior of the Co-Fe-S / MXene composite according to voltage scan rate and current density can be observed. As shown in Figure 4-(f), it can be confirmed that the Co-Fe-S / MXene composite of the present invention has a significantly improved capacitance value (~1230.50 F / g) compared to traditionally reported EDLCs materials. This means that the Co-Fe-S / MXene composite is a material with high rate capability characteristics.

[0104] Figure 4-(g) is a graph showing the results of the lifetime stability evaluation of an electrode containing Co-Fe-S / MXene, and Figure 4-(h) is a graph showing the results of the EIS comparison before and after charging and discharging of an electrode containing Co-Fe-S / MXene.

[0105] As shown in Figures 4-(g) and 4-(h), charge-discharge lifespan stability was evaluated to assess the sustainability of the Co-Fe-S / MXene composite material at a commercial level. The Co-Fe-S / MXene composite electrode exhibited a capacitance retention rate of 95.19% even after 30,000 charge-discharge cycles. In addition, EIS analysis performed before and after long-term charge-discharge confirmed that there was no significant change in the resistance value. These results indicate that the Co-Fe-S / MXene composite possesses long-term lifespan characteristics.

[0107] Experimental Example 4: Analysis of Energy Storage Characteristics of Co-Fe-S / MXene Composite Electrode

[0108] Figure 5 is a graph showing the XRD analysis results of a Co-Fe-S / MXene complex according to one embodiment of the present invention.

[0109] As shown in Fig. 5, XRD analysis of the Co-Fe-S / MXene composite according to the present invention confirmed that it forms a multi-phase structure of cobalt-based sulfides and iron-based sulfides. Furthermore, based on the XRD analysis results, it can be seen that it has a crystal structure different from the existing Co-Fe LDH, and such a multi-phase material can provide more electrochemically active sites due to a larger specific surface area compared to a single-phase material.

[0111] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0112] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

Claim 1 delete Claim 2 delete Claim 3 delete Claim 4 A method for manufacturing a Co-Fe-S / MXene composite comprising: a first step of manufacturing a MXene dispersion; a second step of manufacturing a Co-Fe layered double hydroxide (LDH) / MXene composite by adding a hydrate containing cobalt (Co) and a hydrate containing iron (Fe) to the MXene dispersion; and a third step of manufacturing a Co-Fe-S / MXene composite by adding a hydrate containing sulfur (S) to the Co-Fe layered double hydroxide / MXene composite; wherein the third step is characterized by manufacturing the Co-Fe-S / MXene composite through a hydrothermal synthesis method. Claim 5 A method for preparing a Co-Fe-S / MXene complex according to claim 4, wherein the first step is characterized by preparing a MXene dispersion using sonication. Claim 6 A method for manufacturing a Co-Fe-S / MXene composite according to claim 4, wherein the hydrate containing cobalt in the second step is Co(NO3)2·6H2O and the hydrate containing iron is Fe(NO3)2·4H2O. Claim 7 A method for preparing a Co-Fe-S / MXene complex according to claim 4, wherein the second step further involves adding urea and ammonia fluoride. Claim 8 A method for manufacturing a Co-Fe-S / MXene composite according to claim 4, wherein the second step is characterized by manufacturing a Co-Fe double-layer hydroxide / MXene composite through a hydrothermal synthesis method. Claim 9 A method for manufacturing a Co-Fe-S / MXene composite according to claim 8, characterized in that the hydrothermal synthesis method is performed at 150°C to 200°C. Claim 10 A method for manufacturing a Co-Fe-S / MXene complex according to claim 4, wherein the sulfur-containing hydrate of the third step is Na2S·9H2O. Claim 11 delete Claim 12 A method for manufacturing a Co-Fe-S / MXene composite according to claim 4, characterized in that the hydrothermal synthesis method is performed at 100℃ to 140℃. Claim 13 A Co-Fe-S / MXene composite characterized by being manufactured by any one of the manufacturing methods of claims 4 through 10 and claim 12. Claim 14 A cathode material characterized by comprising a Co-Fe-S / MXene complex according to Clause 13. Claim 15 An asymmetric supercapacitor characterized by including a cathode composed of a cathode material according to claim 14.

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