Supercapacitors containing nanostructures of metallic chalcogen compounds

Abstract

Symmetrical and asymmetrical supercapacitors are disclosed. The symmetrical supercapacitor comprises a first electrode, an electrolyte, and a second electrode. The first and second electrodes comprise nanostructures of a carbon-based material and a metal-chalcogen compound, where the metal is selected from Cu, Va, Ni, Fe, Ag, Co, Mn, Sn and any combination thereof, and the chalcogen is selected from Te, Se, and S. The asymmetrical supercapacitor comprises a substrate, a first electrode, an electrolyte, and a second electrode, where the first electrode comprises a first nanostructure of a first carbon-based material and a metal-chalcogen compound, where the metal is selected from Cu and Sn, and the chalcogen is selected from Te, Se, and S, and the second electrode comprises a second carbon-based material.

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 456,820, filed on April 4, 2023, the entire content of which is incorporated herein by reference.

[0002] The present invention generally relates to supercapacitors. More specifically, the present invention relates to supercapacitors containing nanostructures of metal - chalcogen compounds.

Background Art

[0003] A supercapacitor (also known as an electrochemical capacitor) is a kind of power storage device between a conventional capacitance capacitor and a battery. Supercapacitors have great potential as highly efficient energy storage devices and may become an alternative to batteries in the future.

[0004] Several types of supercapacitors are known and are actually in use. Electric double - layer capacitors (EDLCs), electrochemical pseudocapacitors, and hybrid capacitors are the most common.

[0005] An EDLC typically consists of two carbon - based electrodes, an electrolyte, and a separator. Similar to a normal capacitor, an EDLC accumulates charge through a non - Faradaic process, and no charge conversion occurs between the electrode and the electrolyte. Therefore, the electrode material has chemically static properties at all operating potentials. Various carbon - based materials, such as carbon nanotubes, graphene allotropes, activated carbon black, and carbon aerogels, can be used as electrodes for EDLCs.

[0006] A pseudocapacitor is a type of supercapacitor in which charge is stored through electroadsorption, redox reactions, or insertion processes. In the Faraday charge storage mechanism, charge conversion occurs through a bilayer. Compared to EDLC electrodes, pseudocapacitor electrodes have higher charge storage capacity, but these electrodes have limited cycle stability and low power density due to material degradation affected by phase changes and Faraday reactions. Factors affecting the electrochemical performance of a pseudocapacitor include the specific surface area of ​​the electrodes, particle size, conductivity of the active material, device structure, and type of electrolyte.

[0007] Hybrid supercapacitor configurations leverage the advantages of both double-layer and pseudocapacitor types. Hybrid capacitors possess both Faraday and non-Faraday charge storage mechanisms (EDLC and pseudocapacitor). Under these conditions, the advantages of one system are the disadvantages of the other, and vice versa. Hybridizing EDLC and pseudocapacitor is a dynamic pathway to solve problems associated with both systems. This can be achieved by asymmetrically combining different positive and negative electrodes (EDLC and pseudocapacitor) to leverage the advantages of both electrodes. In such a system, both mechanisms operate simultaneously, and this is known as an asymmetric hybrid capacitor. Furthermore, composite electrodes containing carbon-based materials can be coupled with either metal oxides, metal chalcogenides, or conductive polymers to exhibit both EDLC and pseudocapacitor behavior within a single electrode. Similarly, battery-type hybrids are created by configuring one electrode as a battery-type electrode and the other as a capacitor-type electrode. Due to their highly efficient electrochemical performance and unique combination that can meet the demands of diverse applications, research into supercapacitors has increased dramatically in recent decades and is being further fueled by a rapidly growing field of application.

[0008] Supercapacitors offer advantages such as high power density, safety, a wide operating temperature range, and ultra-fast charging times. Supercapacitors typically charge in the range of seconds to minutes, and their typical cycle life can reach 100,000 cycles with only slight performance degradation. These technical characteristics have made supercapacitors the next generation of energy storage devices. However, they still have low energy density. The energy density of a standard / commercial EDLC supercapacitor device is 10 Wh / kg. -1 It is limited to [a certain range]. Therefore, supercapacitors are currently only used as starters for electric vehicles / cabin door switchers for aircraft, where high power density and short discharge time are required. The bottleneck is the driving range (energy density), which needs to be at least 100km for use in electric vehicles. Therefore, the energy density also needs to be 100Whkg. -1 It needs to exceed a certain limit. In this case, the driving range becomes unlimited with a negligibly short charging time. By using supercapacitors whose energy density performance competes with lithium-ion batteries, the driving performance of electric vehicles can be greatly improved.

[0009] Therefore, the claimed object of the present invention is to provide an improved hybrid supercapacitor suitable for any application, such as an electric vehicle or any other electric unit. [Overview of the project]

[0010] Some aspects of the present invention may relate to supercapacitors. A supercapacitor may comprise a first electrode, an electrolyte, and a second electrode. The first electrode comprises a first carbon-based material and a first nanostructure of a metal-chalcogen compound, where the metal includes Cu, Va, Ni, Fe, Mn, Sn and any combination thereof, and the chalcogen includes Te, Se and S. The second electrode is, (i) A second carbon-based material, and (ii) Second nanostructures of carbon-based materials and metal-chalcogen compounds Selected from, where the metals include Cu, Va, Ni, Fe, Mn, Sn and any combination thereof, and the chalcogens include Te, Se and S.

[0011] Some additional aspects of the present invention may relate to a symmetrical supercapacitor comprising a first electrode, an electrolyte, and a second electrode. In some embodiments, the first and second electrodes comprise a carbon-based material and a nanostructure of a metal-chalcogen compound, where the metal includes Cu, Va, Ni, Co, Ag, Fe, Mn, Sn and any combination thereof, and the chalcogen includes Te, Se and S.

[0012] In some embodiments, one of the first and second electrodes each comprises a first layer containing a carbon-based material and a second layer containing a nanostructure of a metal-chalcogen compound. In some embodiments, the mass loading of the first layer is 0.1 mg / cm³. 2 ~20.0 mg / cm³ 2 The mass load of the second layer is 0.1 mg / cm³. 2 ~20.0 mg / cm³ 2 It is possible.

[0013] In some embodiments, one of each of the first and second electrodes comprises a composite material containing a mixture of a carbon-based material and a nanostructure of a metal-chalcogen compound. In some embodiments, the metal-chalcogen compound has the form of nanoparticles, nanospheres, nanotubes, nanosheets, nanowires, nanoflowers, etc. In some embodiments, the weight ratio of the carbon-based material to the nanostructure of the metal-chalcogen mixture is 1:1 to 1:4.

[0014] In some embodiments, the carbon-based material may include at least one of single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanopearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black.

[0015] In some embodiments, the first layer, which includes oriented SWCNTs, DWCNTs, and MWCNTs, may be parallel to the surface of the second layer.

[0016] In some embodiments, the electrolyte may include KOH, NaOH, NaCl, KCl, Na2SO3, Na2SO4, NaClO4, K2SO3, TEABF4, TBABF4, TBAPF6, TEAPF6, LiClO4, LiCl, LiOH, and Li2SO4. In some embodiments, the electrolyte may be an aqueous or organic gel electrolyte. In some embodiments, the aqueous or organic gel may include at least one of polyvinyl alcohol (PVA), n-methyl-2-pyrrolidone (NMP), cellulose powder, acetonitrile, carboxymethylcellulose (CMC), and sulfonated tetrafluoroethylene fluoropolymer copolymer (Nafion).

[0017] In some embodiments, the electrolyte may be an aqueous solution, and the supercapacitor further comprises a separator. In some embodiments, one of each of the first and second electrodes may further contain an additive. In some embodiments, the additive may be polyvinylidene fluoride (PVDF).

[0018] In some embodiments, the supercapacitor may further include two current collectors, each bonded to the surface of either a first electrode or a second electrode that is not facing the electrolyte.

[0019] In some embodiments, the supercapacitor may further include at least one of the conductive layers joined to at least one of the current collectors. In some embodiments, the at least one conductive layer may include a mixture of 70-90 wt% graphite, 20-5 wt% MWCNT, and a binder.

[0020] Some additional aspects of the present invention may relate to an additional asymmetric supercapacitor that may include a first electrode, an electrolyte, and a second electrode, where the first electrode includes a first carbon-based material and a first nanostructure of a metal-chalcogen compound, where the metal may include at least one of Cu, Va, Ni, Co, Ag, Fe, Mn, Sn, and any combination thereof, and the chalcogen may include Te, Se, and S, and the second electrode may include a second carbon-based material.

[0021] In some embodiments, the carbon-based material may include at least one of single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT), multi-walled carbon nanotubes (MWCNT), carbon nanopearl powder, allotropes of graphene, activated carbon, carbon black, graphite powder, and activated carbon black. In some embodiments, the first electrode may include a first layer including a carbon-based material and a second layer including a nanostructure of a metal-chalcogen compound. In some embodiments, the mass loading of the first layer may be 0.1 mg / cm 2 ~20.0 mg / cm 2 and the mass loading of the second layer may be 0.1 mg / cm 2 ~20.0 mg / cm 2 and may be.

[0022] In some embodiments, the first electrode may comprise a composite material that may include a mixture of a carbon-based material and nanostructures of a metal-chalcogen compound. In some embodiments, the metal-chalcogen compound may be in the form of nanoparticles, nanospheres, nanotubes, nanosheets, nanowires, and nanoflowers. In some embodiments, the weight ratio of the carbon-based material to the nanostructures of the metal-chalcogen mixture may be 1:1 to 1:4.

[0023] In some embodiments, the electrolyte may comprise at least one of KOH, NaOH, NaCl, KCl, Na2SO3, Na2SO4, NaClO4, K2SO3, TEABF4, TBABF4, TBAPF6, TEAPF6, LiClO4, LiCl, LiOH, and Li2SO4. In some embodiments, the electrolyte is an aqueous or organic gel electrolyte. In some embodiments, the aqueous or organic gel may comprise at least one of polyvinyl alcohol (PVA), n-methyl-2-pyrrolidone (NMP), cellulose powder, acetonitrile, carboxymethylcellulose (CMC), and sulfonated tetrafluoroethylene-based fluoropolymer copolymer (Nafion). In some embodiments, the electrolyte may be an aqueous solution, and the supercapacitor may further comprise a separator.

[0024] In some embodiments, the first and second electrodes may further include additives. In some embodiments, the additives may be polyvinylidene fluoride (PVDF) or carboxymethylcellulose (CMC).

[0025] In some embodiments, the supercapacitor may further include two current collectors, each bonded to the surface of a first or second electrode that is not facing the electrolyte.

[0026] In some embodiments, the supercapacitor may further include at least one conductive layer bonded to at least one of the current collectors. In some embodiments, the at least one conductive layer comprises a mixture of 70–90 wt% graphite, 20–5 wt% MWCNTs, and a binder.

[0027] In some embodiments, the supercapacitor may further include a first current collector, a first conductive layer (one side of which is bonded to the first current collector and the first carbon-based material), a second current collector, and a second conductive layer (one side of which is bonded to the second current collector and the second carbon-based material).

[0028] In some embodiments, the first and second conductive layers may comprise a mixture of 70-90% by weight of graphite, 20-5% by weight of MWCNTs, and a binder.

[0029] Some additional aspects of the present invention may relate to a method for manufacturing electrodes for supercapacitors, the method of synthesizing a nanostructure of a metal-chalcogen compound, where the metal may be selected from Cu, Ag, Ni, Co, and Sn and any combination thereof, and the chalcogen may be selected from Te, Se, and S, the method of synthesizing, forming a first layer which may contain a carbon-based material, and depositing a second layer which may contain a nanostructure of a metal chalcogen compound on one side of the first layer.

[0030] In some embodiments, the carbon-based material may include at least one of single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanopearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black.

[0031] In some embodiments, the method may further include depositing electrodes on a current collector. In some embodiments, the method may further include depositing a conductive layer on a current collector before depositing electrodes.

[0032] In some embodiments, the method may further include assembling a supercapacitor using a first electrode, electrolyte, and second electrode according to any one of the embodiments disclosed herein. (i) The second electrode is a carbon-based material deposited on the current collector, and (ii) an electrode selected from any one of the embodiments disclosed herein.

[0033] The subject matter considered to be the present invention is specifically pointed out and explicitly claimed in the concluding section of this specification. However, the present invention, along with both its configuration and method of operation, as well as its object, features and advantages, can be best understood by reading the following detailed description together with the accompanying drawings. [Brief explanation of the drawing]

[0034] [Figure 1A] This is a diagram of a symmetrical supercapacitor according to some embodiments of the present invention. [Figure 1B] This is a diagram of an asymmetrical supercapacitor according to several embodiments of the present invention. [Figure 2] This is a flowchart of a method for manufacturing electrodes for a supercapacitor according to some embodiments of the present invention. [Figure 3] These are X-ray diffraction spectra of 2D SnSe nanosheets according to several embodiments of the present invention. [Figure 4] This shows SEM analysis confirming the surface morphology of 2D SnSe nanosheets according to several embodiments of the present invention. [Figure 5] This is a diagram illustrating the synthesis process of CuSe nanocrystals according to several embodiments of the present invention. [Figure 6]The images shown are SEM images of CuSe according to several embodiments of the present invention. [Figure 7A] The XRD patterns of CuSe according to several embodiments of the present invention are shown. [Figure 7B] The following images show transmission electron microscopy (TEM), high-resolution (HR) TEM, selected-region electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS) of CuSe according to several embodiments of the present invention. [Figure 7C] The nitrogen adsorption / desorption isotherms and pore size distributions of CuSe nanosheets according to several embodiments of the present invention, as well as the BJH pore size distribution curve (inset), are shown. [Figure 8A] The XRD patterns of SnS according to several embodiments of the present invention are shown. [Figure 8B] The images shown are SEM images of SnS nanostructures according to several embodiments of the present invention. [Figure 9] The CV curves and corresponding volume graphs for different electrolytes at a 0.5 M concentration according to several embodiments of the present invention are shown. [Figure 10] The CV curves and corresponding volume graphs for different concentrations of NaOH according to several embodiments of the present invention are shown. [Figure 11] The CV curves and corresponding capacitance graphs at 100 mV / s for different CuSe mass loadings in 2.5 M NaOH according to several embodiments of the present invention are shown. [Figure 12] The electrochemical characterization of 0.45 mg of CuSe nanosheets on an SS substrate according to several embodiments of the present invention is shown. (a) and (b) show the CV curves and corresponding capacities (F / g and mF / cm2) of the CuSe nanosheets at different scanning speeds, and (c) and (d) show the galvanostatic charge-discharge (GCD) curves and corresponding capacities (F / g and mF / cm2) at different current densities. [Figure 13]The electrochemical impedance spectroscopy (EIS) analysis of CuSe nanosheet electrodes according to several embodiments of the present invention is shown, including (a) a Nyquist plot, (b) a fitted equivalent circuit, (c) a Bode phase plot, and (d) a capacitance-to-frequency plot. [Figure 14] The electrochemical stability of CuSe nanosheet electrodes according to several embodiments of the present invention is demonstrated through 3500 repeated CV cycles at 100 mV / s. [Figure 15] Electron microscope images obtained by HR-SEM according to several embodiments of the present invention are shown: (a) low magnification image of CuSe on the carbon tape surface, (b) high magnification image of CuSe on the grid surface, (c) low magnification image of CuSnSe on the carbon tape surface, (d) high magnification image of CuSnSe on the grid surface, (e) low magnification image of SnSe on the carbon tape surface, and (f) high magnification image of SnSe on the grid surface.

[0035] For the sake of simplicity and clarity in the illustrations, it should be understood that the elements shown in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to others for clarity. Furthermore, where deemed appropriate, reference numbers may be repeated between drawings to indicate corresponding or similar elements. [Modes for carrying out the invention]

[0036] Those skilled in the art will understand that the present invention can be carried out in other specific forms without departing from its spirit or essential features. Therefore, the embodiments described herein should be considered illustrative and not limiting in any respect to the invention described herein. Accordingly, the scope of the invention is indicated not by the detailed description above but by the appended claims, and therefore all modifications falling within the meaning and scope of the claims are intended to be encompassed therein.

[0037] Some aspects of the present invention relate to hybrid supercapacitors comprising nanostructures of metallic chalcogen compounds. The hybrid supercapacitors may be symmetrical or asymmetrical. The metallic chalcogen compounds may be provided as nanolayers, nanoparticles, nanospheres, nanotubes, nanosheets, nanowires, and nanoflowers, among others. The metallic chalcogen compounds may be incorporated into the electrodes of the supercapacitor together with carbon-based materials.

[0038] As used herein, “nanostructure” may include any form of crystalline, amorphous, or semicrystalline material having at least one dimension up to 100 nm. For example, a nanolayer may have a thickness of up to 100 nm. Other examples may include nanoparticles having an average diameter of up to 100 nm, nanotubes having an average diameter of up to 100 nm, nanosheets having a thickness of up to 100 nm, nanowires having a width of up to 100 nm, and nanoflowers having an average diameter of up to 100 nm.

[0039] As used herein, "chalcogen" may include elements selected from Te, Se, and S.

[0040] As used herein, "metal" may include metallic elements selected from Cu, Va, Ni, Fe, Sn, and others.

[0041] The carbon-based materials used herein may include any carbon-based form, such as carbon nanolayers, single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanopearl powder, graphite powder, allotropes of graphene, and activated carbon black.

[0042] As used herein, "functionalized carbon-based material" may refer to surface modification including the addition of new carboxyl groups (-COOH), carbonyl groups (-C=O), and hydroxyl groups (-OH), as well as the removal of impurities.

[0043] In some embodiments, the effective electrochemical performance of a supercapacitor directly depends on the selection of the active electrode material and the appropriate electrolyte. The surface morphology, crystal structure, and thickness of the film / layer are parameters for achieving highly efficient electrochemical performance.

[0044] In some embodiments, when fabricating electrodes for supercapacitor applications, the following aspects should be considered: Electrode materials may have a large surface area, porosity, and conductivity to possess excellent electrochemical properties. • The electrolyte can penetrate into the porous surface of the electrode material. By using materials with good electrical conductivity, resistance is reduced, enabling high power supply. • Environmentally friendly and non-toxic electrodes. • Simple, low-cost, and industrially scalable methods can be employed to fabricate large-area electrodes.

[0045] The energy density (E) and power density (P) of a supercapacitor are calculated using equations (1) and (2).

number

[0046] Therefore, the materials and dimensions selected according to embodiments of the present invention relate to manufacturing improved hybrid supercapacitors taking into consideration the above-described aspects.

[0047] Referring now to Figure 1A, this is a diagram of a symmetrical supercapacitor according to some embodiments of the present invention. The supercapacitor 100 may comprise a first electrode 10A, a second electrode 10B, and an electrolyte 20. In the symmetrical supercapacitor, the first electrode 10A and the second electrode 10B have substantially similar structures and form mirror symmetry from both sides of the electrolyte 20 as shown in the figure.

[0048] In some embodiments, one of each of electrodes 10A and 10B may comprise a carbon-based material 12 and a nanostructure 14 of a metallic chalcogen compound, where the metal includes Cu, Va, Ni, Co, Ag, Fe, Mn, Sn and any combination thereof, and the chalcogen includes Te, Se and S. For example, the carbon-based layer 12 may be bonded to the metallic chalcogen nanolayer (or nanosheet) 14. For example, functionalized MWCNTs may be used to form the carbon-based layer 12. In some embodiments, the metal chalcogen compound layer 14 may include at least one of the following: SnSe nanostructures, CuSe nanostructures, CuS nanostructures, CuTe nanostructures, SnTe nanostructures, SnS nanostructures, AgS nanostructures, AgSe nanostructures, AgTe nanostructures, NiS nanostructures, NiSe nanostructures, NiTe nanostructures, CuSnS nanostructures, CuSnSe nanostructures, CuSnTe nanostructures, NiSnS nanostructures, NiSnSe nanostructures, NiSnTe nanostructures, CoSnS nanostructures, CoSnSe nanostructures, CoSnTe nanostructures, AgSnS nanostructures, AgSnSe nanostructures, AgSnTe nanostructures, etc. (including those derived from other metal chalcogens).

[0049] In some embodiments, the metal chalcogen compound 14 has the following chemical formula MSnX, where M is selected from Cu, Ag, Co, Ni, etc., and X is selected from Te, Se, and S.

[0050] In some embodiments, the mass load of layer 12 is 0.1 mg / cm³. 2 ~20 mg / cm³ 2For example, 0.15 mg / cm³ 2 , 0.3 mg / cm³ 2 , 0.5 mg / cm³ 2 , 1 mg / cm³ 2 , 2 mg / cm³ 2 , 5 mg / cm³ 2 , 7 mg / cm³ 2 , 10 mg / cm³ 2 , 15 mg / cm³ 2 , 20 mg / cm³ 2 and any value in between. In some embodiments, the mass load of layer 14 is 0.1 mg / cm³. 2 ~20.0 mg / cm³ 2 For example, 0.1 mg / cm³ 2 , 0.3 mg / cm³ 2 , 0.5 mg / cm³ 2 , 1 mg / cm³ 2 , 2 mg / cm³ 2 , 5 mg / cm³ 2 , 7 mg / cm³ 2 , 10 mg / cm³ 2 , 15 mg / cm³ 2 , 20 mg / cm³ 2 and any value in between.

[0051] In some embodiments, the carbon-based material may be a functionalized carbon-based material, such as functionalized SWCNTs, DWCNTs, MWCNTs, carbon nanopearl powder, carbon black, graphite powder, allotropes of graphene, or activated carbon black.

[0052] In some embodiments, the first layer 12 may include oriented SWCNTs, DWCNTs, and MWCNTs. In such cases, the long axes of the SWCNTs, DWCNTs, and MWCNTs are substantially parallel to the surface of the second layer 14.

[0053] In some embodiments, one of the first electrode 10A and one of the second electrode 10B may comprise a composite material containing a mixture of carbon-based materials and nanostructures of metal chalcogen compounds. For example, electrodes 10A and 10B may comprise a mixture of SnS nanoflowers and MWCNTs or carbon nanopearl powder.

[0054] In some embodiments, the weight ratio of carbon-based material to metal chalcogen mixture to nanostructures is 1:1 to 1:4, for example, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, and any value in between.

[0055] In some embodiments, the electrolyte 20 may be placed between electrodes 10A and 10B. For example, if electrodes 10A and 10B include a metal chalcogen compound layer 14, the electrolyte 20 is placed between the layers 14 as shown in the figure.

[0056] In some embodiments, when composite materials are included, one of the first electrode 10A and one of the second electrode 10B may further contain an additive such as polyvinylidene fluoride (PVDF).

[0057] In some embodiments, the electrolyte 20 may include an aqueous solution containing KOH, NaOH, NaCl, KCl, Na2SO3, Na2SO4, NaClO4, TBABF4, TBAPF6, TEAPF6, K2SO3, TEABF4, LiClO4, LiCl, LiOH, Li2SO4, etc. In such cases, the supercapacitor 100 may further include a separator (not shown). In some embodiments, the separator may be made from cellulose paper or a gel polymer electrolyte membrane.

[0058] In some embodiments, the electrolyte 20 may include an organic gel containing polyvinyl alcohol (PVA), n-methyl-2-pyrrolidone (NMP), cellulose powder, acetonitrile, sulfonated tetrafluoroethylene-based fluoropolymer copolymer (Nafion), carboxymethylcellulose (CMC), etc. The gel may be mixed and therefore may contain one ion from among KOH, NaOH, NaCl, KCl, Na2SO3, Na2SO4, NaClO4, TBABF4, TBAPF6, TEAPF6, K2SO3, TEABF4, LiClO4, LiCl, LiOH, Li2SO4, etc.

[0059] In some embodiments, the supercapacitor 100 may further comprise two current collectors 30, each current collector 30 bonded to the surface of either the first electrode 10A or the second electrode 10B that does not face the electrolyte 20. The current collectors 30 may include any metal sheet such as stainless steel foil / mesh, copper foil, nickel foam / foil, aluminum foil / mesh, or carbon cloth / foam.

[0060] Referring now to Figure 1B, this is a diagram of an asymmetric supercapacitor according to several embodiments of the present invention. The asymmetric supercapacitor 200 may comprise a first electrode 110, a second electrode 120, and an electrolyte 20. In the asymmetric supercapacitor, the first electrode 110 is different from the second electrode 120 in that at least one of the nanostructures of carbon-based material and / or metal chalcogen compounds is different.

[0061] The electrolyte 20 may be substantially the same as the electrolyte 20 of the supercapacitor 100. The supercapacitor 200 may further include a current collector 30, which is substantially the same as the current collector 30 of the supercapacitor 100.

[0062] In some embodiments, the first electrode 110 may comprise a first carbon-based material 112 and a first nanostructure 114 of a metallic chalcogen compound. In such cases, the first electrode 110 may be the positive electrode.

[0063] In some embodiments, the second electrode 120 may consist solely of the second carbon-based material 122. In such cases, the second electrode 120 may be the negative electrode. In some embodiments, the second electrode 120 may also include a second nanostructure of a metal chalcogen compound.

[0064] In some embodiments, the first carbon-based material 112 and the second carbon-based material 122 may be the same or different. In some embodiments, the first and / or second carbon-based material 112 or 122 may include single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanopearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, activated carbon black, and the like.

[0065] In some embodiments, the metal chalcogen compound 114 may comprise a metal selected from Cu and Sn, and a chalcogen selected from Te, Se, and S.

[0066] In some embodiments, the metal chalcogen compound layer 114 may include SnSe nanostructures, CuSe nanostructures, CuS nanostructures, CuTe nanostructures, SnTe nanostructures, SnS nanostructures, AgS nanostructures, AgSe nanostructures, AgTe nanostructures, NiS nanostructures, NiSe nanostructures, NiTe nanostructures, CuSnS nanostructures, CuSnSe nanostructures, CuSnTe nanostructures, NiSnS nanostructures, NiSnSe nanostructures, NiSnTe nanostructures, CoSnS nanostructures, CoSnSe nanostructures, CoSnTe nanostructures, AgSnS nanostructures, AgSnSe nanostructures, AgSnTe nanostructures, etc. (including those derived from other metal chalcogens).

[0067] In some embodiments, the metal chalcogen compound 14 has the following chemical formula MSnX, where M is selected from Cu, Ag, Co, Ni, etc., and X is selected from Te, Se, and S.

[0068] In some embodiments, the first layer 112 may include oriented SWCNTs, DWCNTs, and MWCNTs. In such cases, the long axes of the SWCNTs, DWCNTs, and MWCNTs are parallel to the surface of the second layer 114.

[0069] In some embodiments, the mass load of layer 112 is 0.1 mg / cm³. 2 ~20 mg / cm³ 2 For example, 0.15 mg / cm³ 2 , 0.3 mg / cm³ 2 , 0.5 mg / cm³ 2 , 1 mg / cm³ 2 , 1.5 mg / cm³ 2 , 2 mg / cm³ 2 , 5 mg / cm³ 2 , 7 mg / cm³ 2 , 10 mg / cm³ 2 , 15 mg / cm³ 2 , 20 mg / cm³ 2 and any value in between. In some embodiments, the mass load of layer 114 is 0.1 mg / cm³. 2 ~20.0 mg / cm³ 2 For example, 0.1 mg / cm³ 2 , 0.3 mg / cm³ 2 , 0.5 mg / cm³ 2 , 1 mg / cm³ 2 , 1.5 mg / cm³ 2 , 5 mg / cm³ 2 , 7 mg / cm³ 2 , 10 mg / cm³ 2 , 15 mg / cm³ 2 , 20 mg / cm³ 2 and any value in between.

[0070] In some embodiments, the first electrode 110 may comprise a composite material containing a mixture of carbon-based materials and nanostructures of metal chalcogen compounds. For example, the first electrode 110 may comprise a mixture of SnS nanoflowers and MWCNTs or carbon nanopearl powder.

[0071] In some embodiments, the weight ratio of carbon-based material to nanostructures of metal-chalcogen mixed compounds is 1:1 to 1:4, for example, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, and any value in between.

[0072] In some embodiments, when a composite material is included, the first electrode 110 may further include additives such as polyvinylidene fluoride (PVDF).

[0073] In some embodiments, the electrolyte 20 may be placed between electrodes 110 and 120. For example, if the first electrode 110 includes a metal chalcogen compound layer 114, the electrolyte 20 may be placed between the layer 114 and the second electrode 120, as shown in the figure.

[0074] In some embodiments, the supercapacitor 100 and / or supercapacitor 200 may further include first and second conductive layers 35. The first and second conductive layers 35 may be bonded from one side to the first current collector layer 30 or the second current collector layer 30, and to the first carbon-based materials 12 and 112 or the second carbon-based material 12 or 122, respectively. In some embodiments, the conductive layer 35 may comprise a mixture of 70-90 wt% graphite, 20-5 wt% MWCNTs, and a binder (e.g., a conductive binder (e.g., PVDF, CMC, etc.)). In some embodiments, the mass loading of each of the first and second conductive layers 35 is 0.1 mg / cm³. 2 ~20.0 mg / cm³ 2 It is possible.

[0075] In some embodiments, the supercapacitor 100 and / or supercapacitor 200 may not include the conductive layer 35.

[0076] Referring here to Figure 2, this is a method for fabricating electrodes for supercapacitors according to several embodiments of the present invention. In step 210, nanostructures of a metal chalcogen compound are synthesized. In some embodiments, the metal includes Cu, Ag, Ni, Co, Sn and any combination thereof, and the chalcogen is selected from Te, Se, and S. Several non-limiting examples for synthesizing metal chalcogen compounds are shown in the Examples section below.

[0077] In step 220, a first layer containing a carbon-based material is formed by any known method. For example, the first layer may be deposited on a substrate. The carbon-based material may be mixed with a binder (e.g., PVDF, CMC, etc.) and a solvent (e.g., NMP, water, etc.) and deposited on the substrate by at least one of spray atomization, printing, coating, etc. In some embodiments, the substrate is selected from a current collector layer (e.g., layer 30) or a conductive layer (e.g., layer 35). In some embodiments, the carbon-based material includes single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanopearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black.

[0078] In step 230, a second layer containing nanostructures of a metal chalcogen compound may be deposited on one side of the first layer. The nanostructures may be mixed with a binder (e.g., PVDF, CMC, etc.) and a solvent (e.g., NMP, water, etc.) and deposited on the carbon-based material layer by at least one of spraying, printing, coating, etc.

[0079] In some embodiments, steps 220 and 230 may be combined to form a single layer containing both the carbon-based material and the metallic chalcogen compound. In some embodiments, the carbon-based material and the metallic chalcogen compound may be mixed and deposited on the carbon-based material layer by at least one of the following: spraying, printing, coating, etc.

[0080] In some embodiments, the method may further include depositing electrodes on a current collector, for example, a current collector, for example, a current collector 30.

[0081] In some embodiments, the method may include applying a first conductive layer (e.g., layer 35) onto a current collector (e.g., current collector 30). The method may include mixing 70-90 wt% graphite and 20-5 wt% MWCNTs with a binder (e.g., PVDF, CMC, etc.) and a solvent (e.g., NMP, water, etc.). The mixture is then deposited onto one surface of the current collector by at least spraying, printing, coating, etc.

[0082] In some embodiments, the method may further include assembling a supercapacitor using a first electrode (e.g., electrode 10A or 110), an electrolyte 20, and a second electrode, the second electrode being selected from a carbon-based material deposited on a current collector (e.g., electrode 120) and electrode 10B, as shown in Figures 1A and 1B. [Examples]

[0083] Synthesis of SnSe nanosheets The fabrication of solution-processed, phase-controlled two-dimensional (2D) SnSe nanosheets was carried out by employing a one-pot heating synthesis route. In the one-pot heating synthesis, SnCl4·5H2O, SeO2, 1,10-Phenanthroline and OAM were heated together in a nitrogen (N2) environment. The novel features of this synthesis route are: (1) the use of an inexpensive and non-toxic selenium precursor (SeO2) instead of sodium selenosulfate, an expensive, toxic, and complex selenium source; (2) the preparation of single-phase, single-crystal SnSe through reaction parameter control; and (3) the fact that this synthesis route facilitates the optimization of the two-dimensional morphology of SnSe. In short, 0.05 M SnCl4·5H2O, 0.05 M SeO2, and 0.05 M 1,10-phenanthroline were mixed in 20 mL of OAM. Since selenium is insoluble in water, OAM acts as the solvent here. 1,10-Phen acts as a capping and reducing agent and plays a crucial role in obtaining single-phase SnSe. The mixed solution was stirred for 15 minutes under a nitrogen (N2) atmosphere at a flow rate of 0.5 L / min. The three-necked flask was heated to 120°C at the same N2 flow rate. After reaching 120°C, the flow rate was changed to 1 L / min for 10 minutes. Here again, the solution was heated to 260°C at a flow rate of 0.5 L / min. At 260°C, the flow rate was maintained at approximately 0.1 L / min for the next 30 minutes, and the solution was allowed to cool naturally. Finally, the product was centrifuged at 4500 rpm and purified by adding ethanol and acetone several times.

[0084] Referring now to Figure 3, this is the X-ray diffraction spectrum of a 2D SnSe nanosheet according to several embodiments of the present invention. This spectrum was obtained from synthesized SnSe. Furthermore, Figure 4 shows the SEM analysis results to confirm the surface morphology of the 2D SnSe nanosheet at a concentration of 0.05 M.

[0085] Synthesis of cuSe nanostructures Copper(II) chloride dihydrate (CuCl2·2H2O, 99%, Fisher Chemicals), selenium dioxide (SeO2, 99.4%), 1,10-phenanthroline (C 12H8N2, 99%) and oleylamine (C) 18 H 37 As schematically shown in Figure 5, N, 80-90%, Acros Organics was used directly in the synthesis without further purification. The synthesis of CuSe nanocrystals was carried out using a simple one-pot chemical route with oleylamine as the solvent. In a typical synthesis process, CuCl2·2H2O, SeO2 (molar concentrations of 0.02M, 0.05M, 0.1M, and 0.15M) and 1,10-phenanthroline (0.1M) were dissolved in 20 mL of oleylamine by magnetic stirring, and a precursor solution was formed in a three-necked flask at room temperature under an N2 atmosphere for 15 minutes. The reaction solution was heated to 90°C and held for 10 minutes. Then, the temperature was raised to 180°C and held for 1 hour. After natural cooling to room temperature, the final product was recovered by centrifugation and washed several times with ethanol and acetone.

[0086] Referring now to Figure 6, these are SEM images of CuSe according to several embodiments of the present invention. SEM images of copper selenide structures obtained from reactions at molar concentrations of 0.02, 0.05, 0.1, and 0.15 are shown in Figure 6(a-h). As shown in Figure 6(a, b, c, g, h), the CuSe crystals grow in an irregular pattern. Nanostructures having hexagonal and plate-like shapes are shown in Figure 6(d, e). The thickness of the hexagonal plates ranged from 40 nm to 70 nm. A wide size distribution was observed for the edge lengths of the hexagons, ranging from 89 nm to 235 nm.

[0087] Referring here to Figure 7A, this shows the XRD patterns of CuSe according to several embodiments of the present invention. The crystalline structure and chemical composition of the copper selenide powder were confirmed by XRD. Typical XRD patterns of copper selenides synthesized at concentrations of 0.02 M, 0.05 M, 0.1 M, and 1.15 M are shown in Figure 7A(a-d), indicating the polycrystalline nature of the material. The sharp, narrow peak detected in the XRD pattern from the 0.02 M sample may be due to a mixed phase of copper selenide (Figure 7A(a)). The peak position and intensity were consistent with standard data for hexagonal CuSe (indicated by @), cubic CuSe2 (indicated by *), and Clockmanite CuSe (indicated by @) (JCPDS number 01-086-1240).

[0088] Figure 7A(b) shows the XRD pattern of 0.05 M copper selenide, which can be indexed to the mixed phase. The peak positions and intensities were consistent with standard data for hexagonal CuSe (indicated by @), cubic CuSe2 (indicated by *), and clockmanite-type CuSe (indicated by @).

[0089] The sharp, narrow peaks observed in the XRD pattern of the 0.1 M sample (Figure 7A) can be indexed to the (101), (102), (103), (006), (104), (105), (106), (008), (110), (108), (201), (203), and (208) planes of hexagonal CuSe with a Clockman-type phase. The peak locations and intensities were in good agreement with standard data for hexagonal CuSe.

[0090] Figure 7A(d) shows the XRD pattern of the 0.15 M sample, which can be indexed to the mixed phase. The peak positions and intensities are indicated by @ for hexagonal CuSe, * for cubic CuSe2, and * for Cu 0.87 It matched the standard data for Se.

[0091] For samples prepared at a concentration of 0.1 M, a pure Clockman-type phase of CuSe was confirmed by XRD.

[0092] Referring to Figure 7B, which shows transmission electron microscopy (TEM), high-resolution (HR) TEM, selected-region electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS) data. Figures 7B(a) and 7B(b) show typical TEM and high-resolution (HR) TEM images of a single CuSe nanosheet, revealing a hexagonal nanosheet with clearly resolved 2D lattice fringes. The fringe spacing value of 0.341 nm is in good agreement with the interplanar spacing d value of the (100) plane of Clockmanite CuSe. The SAED pattern (Figure 7B(c)) also suggests a hexagonal structure of the single crystal. Furthermore, the energy-dispersive X-ray spectrum (EDS) (Figure 7B(d)) shows two strong peaks for the Cu and Se elements. Quantitative EDS analysis shows that the atomic ratio of Cu and Se is close to the intrinsic 1:1 stoichiometric ratio, suggesting the uniform purity of the CuSe nanosheet (NS).

[0093] Referring to Figure 7C, this shows the nitrogen adsorption / desorption isotherm and pore size distribution of the CuSe nanosheet, as well as the BJH pore size distribution curve (inset). The surface area and pore size of the CuSe nanostructure were determined from the nitrogen adsorption / desorption isotherm (Figure 9) using the multipoint BET method. The pore size of the CuSe nanosheet was 5.13 nm, and the specific surface area was 10.90 m². 2 It was found to be / g.

[0094] The electrochemical performance of CuSe nanostructure supercapacitors was tested using a three-electrode configuration. CuSe nanostructures were deposited on a stainless steel substrate using the dip-and-dry method. 10 mg of synthesized CuSe powder (0.1 M) was dissolved in 10 ml of ethanol. A stainless steel substrate (1 × 1 cm) was immersed in the prepared CuSe solution for 20 seconds to adsorb CuSe onto the substrate, and then dried by IR heating. This process was repeated 20 times to achieve optimal CuSe coating on the stainless steel substrate. The mass load was calculated by measuring the weight of the substrate before and after deposition and determining the difference (weight difference method).

[0095] Synthesis of SnS nanostructures Tin(II) chloride dihydrate (SnCl2:2H2O, 97% or more), sublimated sulfur (99.5%, Acros Organics), and oleylamine (C 18 H 37 N (80-90%) was used as is without further processing.

[0096] The synthesis of SnS flower-like nanostructures was carried out using a simple and economical one-pot heating method. In a typical synthesis, SnCl2:2H2O (0.05 M) and sulfur (0.1 M) were used as the tin and sulfur sources, and oleylamine (10 ml) was used as the solvent. First, sulfur was added to OA and stirred until the solution turned orange or until the sulfur was completely dissolved in OA. Then, SnCl2:2H2O was added to the solvent and stirred for 10 minutes under an N2 atmosphere. The solution was then heated to 120°C and held at this temperature for 20 minutes. Furthermore, the temperature of the three-necked flask was heated to 180°C and held at this temperature for 1 hour. After natural cooling, the final product was recovered by centrifugation and washed 4-5 times with ethanol.

[0097] Referring here to Figure 8A, this shows the XRD patterns of SnS according to several embodiments of the present invention. The structural features of the synthesized flower-like SnS nanostructures by XRD spectroscopy are shown in Figure 8A. The XRD patterns were recorded in the scanning angle range of 20° to 80°. All observed diffraction peaks of the synthesized nanomaterials could be indexed to orthorhombic SnSe with lattice parameters a=5.6730, b=5.7500, and c=11.7600 Å (JCPDS number 01-079-2193).

[0098] Referring to Figure 8B, this shows SEM images of SnS nanostructures according to several embodiments of the present invention. SEM analysis confirmed the surface morphology of the three-dimensional flower-like SnS nanostructures. Although not shown, SEM images of the three-dimensional flower-like SnS nanostructures were also confirmed by corresponding EDS. The low-magnification SEM image (Figure 8A-a) shows the three-dimensional flower-like SnS nanostructures, and the high-magnification image (Figure 8A-b) clearly shows that the flower-like nanostructures are distributed over a wide area. The average thickness of the three-dimensional flower-like SnS nanostructures is 14 nm. The shown EDS spectra clearly contain Sn and S peaks, clearly suggesting the formation of a tin sulfide phase. Finally, the EDS analysis results strongly agree with the XRD results, confirming that the three-dimensional flower-like SnS nanostructures were sufficiently deposited by the proposed chemical pathway.

[0099] Sensualization of MWCNT 95% pure MWCNTs (length 5-15 μm, outer diameter 15-20 nm) were refluxed with H2O2 at 90°C for 48 hours to fix oxygen-containing functional groups and remove amorphous carbon derivatives. The resulting residue was rinsed several times with double-distilled water (DDW) and dried at 60°C for 12 hours. To obtain a stable dispersion, 0.125 g of MWCNTs were sonicated in the surfactant Triton X-100 with 25 mL of DDW (Tx-100:DDW=1:100) for 1 hour.

[0100] Cyclic voltammetry measurement The mass loading of deposited CuSe was 0.2 mg, and the electrodes were evaluated in various electrolytes such as NaOH, KOH, NaCl, LiCl, and Na2SO3 at a fixed concentration of 0.5 M and a scanning speed of 100 mV / s. In the three-electrode cell configuration, the CuSe electrode was used as the working electrode (WE), Ag / AgCl as the reference electrode (RE), and platinum wire as the counter electrode (CE). A unit area (1 cm²) immersed in different electrolytes was measured. 2 The specific capacitance of the CuSe electrode was estimated from the CV curve according to the following equation (1).

number

[0101] In the formula, Cs is the specific capacity (Fg -1 ) and V is the potential sweep rate (mVs -1 ) is the operating potential window, I is the current response (mA), and m is the deposition mass of the sample electrode.

[0102] Referring now to Figure 9, this shows a CV graph recorded at a scanning speed of 100 mV / s using equation (1). Figure 9(a) shows the CV curves for different electrolytes with a concentration of 0.5 M, and Figure 9(b) shows the corresponding specific volume graphs.

[0103] Table 1 shows the specific volume and area volume values ​​of CuSe for different electrolytes. [Table 1]

[0104] Compared to other electrolytes, the CuSe electrode exhibited a good current distribution and a large CV area in the NaOH electrolyte, and its high specific capacity was observed from the CV curve.

[0105] Therefore, we selected NaOH electrolyte and performed concentration optimization using CV. As shown in Figure 10, the concentration of NaOH was increased from 0.5 M to 3 M in 0.5 M increments, and the corresponding CV curves were recorded and analyzed with a fixed mass load (0.2 mg) and a scanning speed of 100 mV / s.

[0106] Figure 10(a) shows the CV curves at different concentrations of NaOH, and Figure 10(b) shows the corresponding volume graphs. The calculated specific volume values ​​are shown in Table 2 below.

[0107] [Table 2]

[0108] In several embodiments, an increase in capacity was observed after changes in electrolyte concentration. The highest capacity was observed at two different concentrations, namely 1.5 M and 2.5 M NaOH. However, the current distribution at 2.5 M NaOH was relatively better than at 1.5 M NaOH, which is advantageous for device fabrication. Changes in mass loading were carried out using the optimized electrolyte concentration, i.e., 2.5 M NaOH. CVs were performed for different mass loadings, and the results are shown in Figure 11.

[0109] Figure 11(a) shows the CV curves for different CuSe mass loadings in 2.5 M NaOH at 100 mV / s, and Figure 11(b) shows the corresponding capacity graphs.

[0110] The calculated specific capacity values ​​are shown in Table 3. Table 3 shows the specific capacity and area capacity values ​​of CuSe for different mass loads. [Table 3]

[0111] Referring to Figure 12, this shows electrochemical measurements at a mass loading of CuSe on SS (0.45 mg) and a molar concentration of NaOH (2.5 M). For CuSe, CV curves at various scanning speeds were evaluated and are shown in Figure 12(a). The specific capacity was observed to decrease as the scanning speed increased from 2 mV / s to 100 mV / s (Figure 12(b)), which may be due to temporal constraints in the electrolytic interaction process. The maximum capacity value of CuSe nanosheets was 718.04 F / g (323.12 mF / cm²) at a scanning speed of 2 mV / s. 2 It was found that...

[0112] Figure 12 shows the electrochemical characterization of 0.45 mg of CuSe nanosheets on an SS substrate. (a) and (b) show the CV curves of the CuSe nanosheets at different scanning speeds and their corresponding capacities (F / g and mF / cm²). 2(c) and (d) show the galvanostatic charge-discharge (GCD) curves at different current densities and their corresponding capacities (F / g and mF / cm²). 2 This indicates that...

[0113] All calculated capacity values ​​are shown in Table 4.

[0114] Table 4 shows the specific capacitance and area capacitance values ​​of CuSe for different scanning speeds. [Table 4]

[0115] The rate characteristics of the materials in devices according to several embodiments of the present invention were confirmed / measured using galvanostatic charge-discharge (GCD) at different current densities from 4 A / g to 1 A / g, as shown in Figure 12(c). The maximum capacity at a current density of 1 A / g was 272.34 F / g (122.56 mF / cm²). 2 It was found that... Capacitance values ​​for different current densities were calculated and are shown in Table 5.

[0116] Table 5 contains the specific capacitance and area capacitance values ​​of CuSe for different current densities. [Table 5]

[0117] Electrochemical Impedance Spectroscopy (EIS) Test EIS evaluation is one of the most important factors for supercapacitor electrodes. To elucidate the sources of electrical conductivity, ion diffusion, charge transfer mechanisms, and capacitance behavior, electrochemical impedance spectroscopy (EIS) tests were performed using Nyquistographs (Z′ vs Z″) in the frequency range of 1 Hz to 100 kHz (a). Two distinct parts of the Nyquist plot, namely the semicircular curves and linear rises in the high and low frequency ranges, clearly indicate the electrochemical properties of the device. As can be seen in Figure 13(a), the impedance results were investigated by semi-quantitative fitting using equivalent circuit simulations of R(Q(R(QR))) (Figure 13(b)).

[0118] In the high-frequency region, the intersection of semicircles has an internal resistance (R s This indicates the charge transfer resistance (R) involved in the electrochemical process during electrochemical operation, which is formed by a combination of contact resistance at the material interface, internal resistance of the substrate, and ionic resistance of the electrolyte. ct ) is determined. The constant phase element (CPE, Q) consists of two parts: (i) admittance Yo(S.sn) and (ii) a fractional element n which can be in the range of 0 to 1. When n is close to 1, the behavior of the electrode looks similar to that of a perfect capacitor. Figure 13(a) shows the Nyquist plot of CuSe fitted to the equivalent circuit R(Q(R(QR))). Here, the black data represents the measured data and the red data represents the fitted (calculated) data. Figure 13 shows the least chi-squared value of 10 -4 The fitting is good, on the order of magnitude. The fitted circuit has a impedance of 0.75 Ωcm. 2 Small solution resistance (R s ) and 161.90 Ωcm 2 The charge transfer resistance (R ct This indicates that...

[0119] Figures 13(c) and 13(d) are Bode plots showing phase angle and capacitance versus frequency. From Figure 13(c), the electrode exhibits a maximum phase angle of 64.63°, which is 90° for an ideal capacitor, meaning that this electrode exhibits capacitive properties. An important variable is the relaxation time constant of the supercapacitor electrode (τ0 = 1 / f0, f0 = characteristic frequency). A short relaxation time indicates that electrolyte ions reach the membrane and the electrochemical cell is still rapidly recharging while reaching its maximum capacitance. This indicates that rapid charge diffusion occurs during the reversible insertion / extraction operation, and the estimated τ0 was 0.2 seconds (Figure 13(c)). Furthermore, since the resistive impedance and capacitive impedance are equal at a phase angle of -45°, τ0 was calculated from the frequency versus phase angle plot (Figure 13(c)). The electrode relaxation time of 0.2 seconds indicates the rate at which the accumulated charge can be efficiently distributed. The calculated τo was 0.2 seconds (Figure 13(d)), indicating that rapid charge diffusion occurs during the reversible insertion / extraction process.

[0120] Electrochemical stability Since stability affects the supercapacitor performance of the electrode, the electrode stability (capacitance retention rate) was investigated over 3500 CV cycles at a scanning speed of 100 mV / s. Figure 14 shows the capacitance retention rate against the number of CV cycles, with the CV cycles shown in the inset. A very good capacitance retention rate of approximately 96.41% was observed from the stability measurements. Therefore, Figure 14 demonstrates the electrochemical stability of the CuSe nanosheet electrode through 3500 repeated CV cycles at 100 mV / s.

[0121] Additional synthesis of CuSe and SnSe in aqueous solution Copper chloride dihydrate (CuCl2:2H2O, 99%), tin chloride dihydrate (SnCl2:2H2O, ≥98%), selenium powder (Se, 99.5%, Fisher Chemicals), carbon black SUPER P (99%) / Super P(registered trademark), BLACK PEARLS(registered trademark), VULCAN(registered trademark) (99%) / AC(TOB), L-ascorbic acid (C6H8O6, 99%), sodium boride (NaBH4, 99%). All materials were AR (Arrow Form) and used as is without any additional processing. Water purified using a Milli-Q system with a resistivity greater than 15 MΩ·cm was used throughout the experiments. CuSe, SnSe, CuSe@carbon black, and SnSe@carbon black were synthesized using all of the above materials, respectively. A modified Crichton-type synthesis method was used. For M=Cu, Sn, Co, Ni, or Ag, an aqueous solution of metal cation / metal alloy solution (50 mL, Mn+ concentration 0.03 M) was prepared in flask A. Next, solid L-ascorbic acid (0.02 M) was added to this solution. The solution in flask A was vigorously stirred and heated to 70-80°C (Solution A). Simultaneously, an aqueous solution of Se powder (50 mL, 0.03 M) was prepared in flask B (Solution B). Solution B was vigorously stirred and heated to 70-80°C. When the solution reached 70°C, a strong reducing agent such as sodium borohydride (NaBH4, 0.06 M) was added. After the heating step, without further heating, Solution A was rapidly added to Solution B while vigorously stirring. The mixed solution was cooled to room temperature over 2 hours while stirring. In the next step, the mixed solution was centrifuged to obtain a black precipitate. The precipitate was washed several times with water and then with alcohol. Finally, the black nanostructures were dried in an oven at 85°C for at least 2 hours, preferably overnight.

[0122] To create other chalcogenide materials, we tested combinations of additional metal cations. We investigated the effects of various reducing agents, such as NaBH4, NaOH, and ascorbic acid, on nanostructures at various concentrations, including 0.03 M, 0.06 M, and 0.12 M.

[0123] Synthesis of AgSe and CuSnSe nanostructures AgSe and CuSnSe nanostructures were synthesized using copper chloride dihydrate (CuCl2:2H2O, 99%), tin chloride dihydrate (SnCl2:2H2O, ≥98%), silver nitrate (AgNO3, 99%), and selenium powder (Se, 99.5%, Fisher Chemicals). A modified Crichton-type synthesis method was used. For M=Cu, Sn, or Ag, a metal cation / metal alloy solution (50 mL, M) was used. n+ An aqueous solution of 0.03 M was prepared in flask A. Next, solid L-ascorbic acid (0.02 M) was added to this solution. The solution in flask A was vigorously stirred and heated to 70-80°C (Solution A). Simultaneously, an aqueous solution of Se powder (50 mL, 0.03 M) was prepared in flask B (Solution B). Solution B was vigorously stirred and heated to 70-80°C. When the solution reached 70°C, a strong reducing agent such as sodium borohydride (NaBH4, 0.06 M) was added. After the heating step, Solution A was rapidly added to Solution B while vigorously stirring without further heating. The mixed solution was cooled to room temperature over 2 hours while stirring. In the next step, the mixed solution was centrifuged to obtain a black precipitate. The precipitate was washed several times with water, and then washed with alcohol. Finally, the black nanostructures were dried overnight in an oven at 85°C.

[0124] To create alloyed nanostructures such as Cu-Sn and Ag-Sn, additional metal cation combinations were tested. In this case, aqueous mixtures of the metal cations at the same concentrations as described above were used, followed by the same procedure. Furthermore, the effects of different reducing agents, such as NaOH and ascorbic acid, and various concentrations such as 0.03M, 0.06M, and 0.12M were tested on the nanostructures.

[0125] Referring now to Figure 15, this shows HR-SEM images of some of the metal chalcogen nanostructures disclosed above. The images in Figure 15 include (a) a low-magnification image of CuSe on a carbon tape surface, (b) a high-magnification image of CuSe on a grid surface, (c) a low-magnification image of CuSnSe on a carbon tape surface, (d) a high-magnification image of CuSnSe on a grid surface, (e) a low-magnification image of SnSe on a carbon tape surface, and (f) a high-magnification image of SnSe on a grid surface, according to several embodiments of the present invention.

[0126] Unless otherwise explicitly stated, embodiments of the methods described herein are not limited to a specific order or arrangement. Furthermore, all formulas described herein are intended to be illustrative only, and other or different formulas may be used. In addition, some or some elements of the embodiments of the methods described herein may occur or be performed at the same time.

[0127] While certain features of the present invention are illustrated and described herein, many modifications, substitutions, alterations, and equivalents may arise for those skilled in the art. Therefore, the appended claims are understood to be intended to encompass all such modifications and alterations that fall within the true spirit of the present invention.

[0128] Various embodiments are presented. Each of these embodiments may, naturally, include features of other embodiments presented. Furthermore, embodiments not specifically described may also include various features described herein.

Claims

1. A supercapacitor comprising a first electrode, an electrolyte, and a second electrode, The first electrode comprises a first carbon-based material and a nanostructure of a first metal-chalcogen compound, wherein the metal comprises at least one of Cu, Va, Ni, Fe, Mn, Sn, and any combination thereof, and the chalcogen comprises Te, Se, and S. The second electrode is, (i) a second carbon-based material; and (ii) Nanostructures of the second carbon-based material and the second metal-chalcogen compound; Selected from, where the metal includes at least one of Cu, Va, Ni, Fe, Mn, Sn, and any combination thereof, and the chalcogen includes Te, Se, and S. Supercapacitor.

2. The supercapacitor according to claim 1, wherein the first electrode comprises a first layer containing the carbon-based material and a second layer containing the nanostructure of the metal-chalcogen compound.

3. The mass load of the first layer is 0.1 mg / cm³. ２ ~0.3 mg / cm ２ The mass load of the second layer is 0.2 mg / cm³. ２ ~10.0mg / cm ２ The supercapacitor according to claim 2.

4. The supercapacitor according to claim 1, wherein the first electrode comprises a composite material comprising a mixture of the carbon-based material and the nanostructure of the metal-chalcogen compound.

5. The first current collector and A first conductive layer and The second current collector and A second conductive layer, A supercapacitor according to any one of claims 1 to 4, further comprising: The first conductive layer is bonded to the first current collector and the first carbon-based material from one side. The second conductive layer is bonded to the second current collector and the second carbon-based material from one side. Supercapacitor.

6. The supercapacitor according to claim 5, wherein the first and second conductive layers comprise a mixture of 70 to 90% by weight of graphite, 20 to 5% by weight of multilayer carbon nanotubes (MWCNTs), and a binder.

7. The supercapacitor according to any one of claims 1 to 6, wherein the nanostructure of the metal-chalcogen compound includes a form selected from nanoparticles, nanotubes, nanospheres, nanosheets, nanowires, and nanoflowers.

8. The supercapacitor according to any one of claims 1 to 7, wherein the carbon-based material comprises at least one of single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanopearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black.

9. The supercapacitor according to claim 8, wherein the first layer, which includes oriented SWCNTs, DWCNTs, and MWCNTs, extends parallel to the surface of the second layer.

10. The electrolytic solution contains at least one of KOH, NaOH, NaCl, KCl, Na ２ SO ３ , Na ２ SO ４ , NaClO ４ , TBABF ４ , TBAPF ６ , TEAPF ６ , K ２ SO ３ , TEABF ４ , LiClO ４ , LiCl, LiOH and Li ２ SO ４ The supercapacitor according to any one of claims 1 to 9.

11. The supercapacitor according to any one of claims 1 to 10, wherein the electrolyte is an aqueous or organic gel electrolyte.

12. The supercapacitor according to claim 11, wherein the aqueous or organic gel comprises at least one of polyvinyl alcohol (PVA), n-methyl-2-pyrrolidone (NMP), cellulose powder, acetonitrile, carboxymethylcellulose (CMC), and sulfonated tetrafluoroethylene-based fluoropolymer copolymer (Nafion).

13. The supercapacitor according to any one of claims 1 to 12, wherein the electrolyte is an aqueous solution and the supercapacitor further comprises a separator.

14. The supercapacitor according to any one of claims 1 to 13, wherein one of the first and second electrodes further comprises an additive.

15. The supercapacitor according to claim 14, wherein the additive is polyvinylidene fluoride (PVDF).

16. The supercapacitor according to claim 1, further comprising two current collectors, each bonded to the surface of either the first electrode or the second electrode that is not facing the electrolyte.

17. A supercapacitor comprising a first electrode, an electrolyte, and a second electrode, One of the first electrode and one of the second electrode, Carbon-based materials and Metal-chalcogen compound nanostructures The metal comprises at least one of Cu, Ag, Ni, Co, Sn, or any combination thereof, and the chalcogen is selected from Te, Se, S, or any combination thereof. Supercapacitor.

18. The supercapacitor according to claim 17, wherein one of the first electrode and one of the second electrode each comprises a first layer containing the carbon-based material and a second layer containing the nanostructure of the metal-chalcogen compound.

19. The mass load of the first layer is 0.1 mg / cm³. ２ ~20.0mg / cm ２ The mass load of the second layer is 0.1 mg / cm³. ２ ~20.0mg / cm ２ The supercapacitor according to claim 18.

20. The supercapacitor according to claim 19, wherein one of the first electrode and one of the second electrode comprises a composite material comprising a mixture of the carbon-based material and the nanostructure of the metal-chalcogen compound.

21. The supercapacitor according to claim 20, wherein the weight ratio of the carbon-based material to the nanostructure of the metal-chalcogen mixed compound is 1:1 to 1:

4.

22. The aforementioned nanostructure is 9 m ２ A supercapacitor according to claims 17 to 21, having a pore diameter exceeding / g.

23. The supercapacitor according to claims 17 to 21, wherein the nanostructure has a pore size of 4 to 6 nm.

24. A method for manufacturing electrodes for supercapacitors, A step of synthesizing a nanostructure of a metal-chalcogen compound, wherein the metal is selected from at least one of Cu, Ag, Ni, Co, and Sn, and any combination thereof, and the chalcogen is selected from Te, Se, and S. The steps include forming a first layer containing a carbon-based material, The steps include depositing a second layer containing the nanostructure of the metal-chalcogen compound on one side of the first layer, A method that includes this.

25. The method according to claim 24, wherein the carbon-based material comprises at least one of single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanopearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black.

26. The method according to claims 24 and 25, further comprising depositing the electrodes on a current collector.

27. The method according to claim 26, further comprising depositing a conductive layer on the current collector before depositing the electrodes.

28. The method according to claim 26 or 27, further comprising assembling a supercapacitor using a first electrode, an electrolyte, and a second electrode as described in any one of claims 24 and 25, wherein the second electrode is (i) Carbon-based material deposited on the current collector; and (ii) The electrode according to any one of claims 24 and 25; A method to be selected from.

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