Supercapacitors comprising nanostructures of metal chalcogen compounds

Abstract

The invention discloses a symmetric and asymmetric supercapacitor. The symmetric supercapacitor includes: a first electrode; an electrolyte; and a second electrode. The first and second electrodes include a nanostructure of a carbon-based material and a metal chalcogen compound, where the metal is selected from the group consisting of Cu, Va, Ni, Fe, Ag, Co, Mn, Sn, and any combination thereof, and the chalcogen is selected from the group consisting of Te, Se, and S. The asymmetric supercapacitor includes: a substrate; a first electrode comprising a first carbon-based material and a first nanostructure of a metal chalcogen compound wherein the metal is selected from Cu and Sn and the chalcogen is selected from Te, Se and S; an electrolyte; and a second electrode comprising a second carbon-based material.

Description

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

[0002] This invention generally relates to supercapacitors. More specifically, this invention relates to supercapacitors comprising nanostructures of metal chalcogenide compounds. Background Technology

[0003] Supercapacitors, also known as electrochemical capacitors, are a type of electrical energy storage device that falls between traditional electrostatic capacitors and batteries. As a highly efficient energy storage device, supercapacitors have enormous potential and may become a future replacement for batteries.

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

[0005] EDLCs typically consist of two carbon-based electrodes, an electrolyte, and a separator. Similar to ordinary capacitors, EDLCs store charge in a non-Radatian manner, with no charge transfer between the electrodes and the electrolyte. Therefore, the electrode materials are static at all operating potentials. Various carbon-based materials can be used as EDLC electrodes, such as carbon nanotubes, allotropes of graphene, activated carbon black, and carbon aerogels.

[0006] Pseudocapacitors are supercapacitors that store charge through electroadsorption, redox reactions, or intercalation processes. In the Faraday charge storage mechanism, charge conversion occurs between the bilayers. Compared to EDLC electrodes, pseudocapacitor electrodes have higher charge storage capacity, but due to phase transitions and Faraday reactions affecting material degradation, these electrodes have limited cycle stability and low power density. Factors affecting the electrochemical performance of pseudocapacitors include the electrode's specific surface area, particle size, the conductivity of the active material, device structure, and electrolyte type.

[0007] Hybrid supercapacitor configurations leverage the advantages of both double-layer and pseudocapacitors. Hybrid capacitors possess both Faraday and non-Faraday charge storage mechanisms (EDLC and pseudocapacitors). In this case, an advantage of one system is a disadvantage of the other, and vice versa. Hybrid EDLC and pseudocapacitors represent a dynamic path to addressing the problems associated with these two systems. This can be achieved through asymmetric combinations of different positive and negative electrodes (EDLC and pseudocapacitors) to utilize the strengths of both electrodes. The simultaneous operation of these two mechanisms in such a system is termed an asymmetric hybrid capacitor. Furthermore, composite electrodes with carbon-based materials are fused with metal oxides, metal chalcogenides, or conductive polymers, exhibiting both EDLC and pseudocapacitor behaviors in a single electrode. Similarly, a battery-type hybrid is created by treating one electrode as a battery-type and the other as a capacitor-type electrode. Due to their highly efficient electrochemical performance and unique combinations that can meet the needs of a wide range of applications, research on supercapacitors has increased dramatically in the past few decades and is thriving through many emerging applications.

[0008] Supercapacitors offer advantages such as high power density, safety, wide operating temperature range, and ultra-fast charging time. Charging times for supercapacitors typically range from seconds to minutes, and their typical cycle life can reach 100,000 cycles with only a slight performance degradation. These technical characteristics make supercapacitors a potential next-generation energy storage device. However, their energy density remains relatively low. The energy density of standard / commercial EDLC supercapacitor devices is limited to 10 Wh / kg. -1 Therefore, supercapacitors are currently only used in electric vehicle starters and aircraft door switches, which require high power density and short discharge times. The bottleneck is the driving range (energy density), which should be at least 100 kilometers for use in electric vehicles. Therefore, the energy density must also be greater than 100 Wh / kg. -1 In this scenario, the driving range is virtually unlimited, while the charging time is negligible. Using supercapacitors can significantly improve the mobility of electric vehicles, as their energy density performance is comparable to that of lithium-ion batteries.

[0009] Therefore, the purpose of the claimed invention is to provide an improved hybrid supercapacitor suitable for any application, such as electric vehicles or any other electric drive unit. Summary of the Invention

[0010] Some aspects of the present invention relate to supercapacitors. A supercapacitor may include a first electrode comprising a first carbon-based material and a first nanostructure of a metal chalcogenide compound, wherein the metal comprises Cu, Va, Ni, Fe, Mn, Sn, and any combination thereof, and the chalcogenide comprises Te, Se, and S; an electrolyte; and a second electrode selected from: (i) Second carbon-based materials; and (ii) A second carbon-based material and a second nanostructure of a metal chalcogenide compound, wherein the metal includes Cu, Va, Ni, Fe, Mn, Sn and any combination thereof, and the chalcogenide includes Te, Se and S.

[0011] Some additional aspects of the present invention relate to a symmetrical supercapacitor comprising: a first electrode; an electrolyte; and a second electrode. In some embodiments, the first and second electrodes comprise nanostructures of carbon-based materials and metal chalcogenide compounds, wherein the metal includes Cu, Va, Ni, Co, Ag, Fe, Mn, Sn, and any combination thereof, and the chalcogenide includes Te, Se, and S.

[0012] In some embodiments, each of the first and second electrodes comprises: a first layer containing a carbon-based material and a second layer containing a nanostructure of a metal chalcogenide compound. In some embodiments, the mass loading of the first layer is 0.1 mg / cm². 2 Up to 20.0 mg / cm 2 Between these points, the mass load of the second layer can be 0.1 mg / cm². 2 Up to 20.0 mg / cm 2 between.

[0013] In some embodiments, each of the first and second electrodes comprises a composite material containing a mixture of a carbon-based material and a metal chalcogenide compound nanostructure. In some embodiments, the morphology of the metal chalcogenide compound includes nanoparticles, nanospheres, nanotubes, nanosheets, nanowires, nanoflowers, etc. In some embodiments, the weight ratio between the carbon-based material and the metal chalcogenide compound nanostructure is between 1:1 and 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 nanoparticles, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black.

[0015] In some implementations, the first layer comprising 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, TBAPF4, TBAPF6, TBAPF6, 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, carboxymethyl cellulose (CMC), and sulfonated tetrafluoroethylene vinyl fluoropolymer copolymer (Nafion).

[0017] In some embodiments, the electrolyte may be an aqueous solution, and the supercapacitor further includes a separator. In some embodiments, each of the first and second electrodes may also include 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 current collector being connected to the non-electrolyte-facing surface of the first or second electrode.

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

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

[0021] 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 nanoparticles, allotropes of graphene, activated carbon, carbon black, graphite powder, and activated carbon black. In some embodiments, the first electrode may include a first layer of carbon-based material and a second layer comprising a nanostructure of a metal chalcogenide compound. In some embodiments, the mass load of the first layer may be 0.1 mg / cm². 2 Up to 20.0 mg / cm 2 Between these points, the mass load of the second layer can be 0.1 mg / cm².2 Up to 20.0 mg / cm 2 between.

[0022] In some embodiments, the first electrode may include a composite material, which may comprise a mixture of a carbon-based material and a nanostructure of a metal chalcogenide compound. In some embodiments, the morphology of the metal chalcogenide compound includes nanoparticles, nanospheres, nanotubes, nanosheets, nanowires, and nanoflowers. In some embodiments, the weight ratio between the carbon-based material and the nanostructure of the metal chalcogenide compound mixture may be between 1:1 and 1:4.

[0023] In some embodiments, the electrolyte may include at least one selected from KOH, NaOH, NaCl, KCl, Na₂SO₃, Na₂SO₄, NaClO₄, K₂SO₃, TEABF₄, TBAPF₄, TBAPF₆, TBAPF₆, 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 include at least one selected from polyvinyl alcohol (PVA), n-methyl-2-pyrrolidone (NMP), cellulose powder, acetonitrile, carboxymethyl cellulose (CMC), and sulfonated tetrafluoroethylene vinyl fluoropolymer copolymer (Nafion). In some embodiments, the electrolyte may be an aqueous solution, and the supercapacitor may further include 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 carboxymethyl cellulose (CMC).

[0025] In some embodiments, the supercapacitor may further include two current collectors, each current collector being connected to the non-electrolyte-facing surface of the first or second electrode.

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

[0027] In some embodiments, the supercapacitor may further include a first current collector; a first conductive layer connected from one side to the first current collector and the first carbon-based material; a second current collector; and a second conductive layer connected from one side 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 to 90 wt% graphite, 20 to 5 wt% MWCNT and adhesive.

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

[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 nanoparticles, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black.

[0031] In some embodiments, the method may further include depositing an electrode on the current collector. In some embodiments, the method may further include depositing a conductive layer on the current collector prior to depositing the electrode.

[0032] In some embodiments, the method may further include assembling a supercapacitor using a first electrode, an electrolyte, and a second electrode according to any of the embodiments disclosed herein, wherein the second electrode is selected from; (i) carbon-based materials deposited on the collector; and (ii) An electrode according to any of the embodiments disclosed herein. Attached Figure Description

[0033] The subject matter of the invention is specifically pointed out and explicitly claimed in the conclusion section of the specification. However, the organization and operation of the invention, as well as its objects, features, and advantages, can be best understood by referring to the following detailed description when read in conjunction with the accompanying drawings, wherein: Figure 1A This is an illustration of a symmetrical supercapacitor according to some embodiments of the present invention; Figure 1B This is an illustration of an asymmetric supercapacitor according to some 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 This is an X-ray diffraction pattern of 2D SnSe nanosheets according to some embodiments of the present invention; Figure 4 SEM analysis confirming the surface morphology of 2D SnSe nanosheets according to some embodiments of the present invention is shown; Figure 5This is a diagram illustrating the synthesis process of CuSe nanocrystals according to some embodiments of the present invention; Figure 6 SEM images of CuSe according to some embodiments of the present invention are shown; Figure 7A The XRD patterns of CuSe according to some embodiments of the present invention are shown; Figure 7B Transmission electron microscopy (TEM), high-resolution (HR) TEM, selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS) of CuSe according to some embodiments of the present invention are shown. Figure 7C The nitrogen adsorption / desorption isotherms and pore size distribution of CuSe nanosheets according to some embodiments of the present invention are shown (inset); Figure 8A The XRD patterns of SnS according to some embodiments of the present invention are shown; Figure 8B SEM images of SnS nanostructures according to some embodiments of the present invention are shown; Figure 9 The CV curves and corresponding capacitance plots of different electrolytes at a concentration of 0.5 M are shown according to some embodiments of the present invention. Figure 10 The CV curves and corresponding capacitance plots at different NaOH concentrations are shown according to some embodiments of the present invention; Figure 11 The CV curves and corresponding capacitance plots are shown in 2.5 M NaOH at 100 mV / s under different CuSe mass loadings according to some embodiments of the present invention. Figure 12 Electrochemical characterization (a, b) of 0.45 mg CuSe nanosheets on an SS substrate according to some embodiments of the present invention is shown. The CV curves of the CuSe nanosheets at different scan rates and their corresponding capacitances (in F / g and mF / cm) are also shown. 2 (c, d) Constant current charge-discharge (GCD) curves at different current densities and their corresponding capacitances (in F / g and mF / cm). 2 ); Figure 13 Electrochemical impedance spectroscopy analysis of CuSe nanosheet electrodes according to some embodiments of the present invention is shown, including (a) Nyquist plot, (b) fitted equivalent circuit, (c) Bode phase plot and (d) capacitance Vs frequency. Figure 14Electrochemical stability of CuSe nanosheet electrodes at 100 mV / s for 3500 repeated CV cycles is shown according to some embodiments of the invention; and Figure 15 The following are electron microscope images of HR-SEM according to some embodiments of the present invention: (a) low magnification CuSe on the surface of the ribbon (b) high magnification CuSe on the surface of the grid (c) low magnification CuSnSe on the surface of the ribbon (d) high magnification CuSnSe on the surface of the grid (e) low magnification SnSe on the surface of the ribbon (f) high magnification SnSe on the surface of the grid.

[0034] It should be understood that, for the sake of simplicity and clarity, the elements shown in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to others for clarity. Furthermore, reference figures may be repeated between figures where deemed appropriate to indicate corresponding or similar elements. Detailed Implementation

[0035] Those skilled in the art will recognize that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the above-described embodiments should be considered in all respects as illustrative rather than restrictive of the invention described herein. Consequently, the scope of the invention is indicated by the appended claims rather than by the foregoing description, and all variations within the equivalent meaning and scope of the claims are intended to be included therein.

[0036] Some aspects of this invention relate to hybrid supercapacitors comprising nanostructures of metal chalcogenide compounds. The hybrid supercapacitor can be a symmetric or asymmetric supercapacitor. The metal chalcogenide compound can be provided as nanolayers, nanoparticles, nanospheres, nanotubes, nanosheets, nanowires, and nanoflowers, etc. The metal chalcogenide compound can be included together with carbon-based materials in the electrodes of the supercapacitor.

[0037] As used herein, “nanostructure” can include any morphology of crystalline, amorphous, or semi-crystalline materials having at least one dimension of up to 100 nm. For example, a nanolayer can have a thickness of up to 100 nm. Other examples may include nanoparticles with an average diameter of up to 100 nm, nanotubes with an average diameter of up to 100 nm, nanosheets with a thickness of up to 100 nm, nanowires with a width of up to 100 nm, and nanoflowers with an average diameter of up to 100 nm.

[0038] As used herein, “chalcogens” may include elements selected from Te, Se, and S.

[0039] As used in this article, "metal" can include metallic elements selected from Cu, Va, Ni, Fe, Sn, etc.

[0040] As used herein, carbon-based materials may include any carbon-based morphology, such as carbon nanolayers, single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanoparticles, graphite powder, allotropes of graphene, activated carbon black, etc.

[0041] As used herein, “functionalized carbon-based materials” can refer to modifications of surface sites, including the connection of new carboxyl (-COOH), carbonyl (-C=O) and hydroxyl (-OH) functional groups, as well as the removal of impurities.

[0042] In some implementations, the effective electrochemical performance of a supercapacitor depends directly on the selection of the active electrode material and a suitable electrolyte. The surface morphology, crystal structure, and thickness of the thin film / layer are parameters for achieving high-efficiency electrochemical performance.

[0043] In some implementations, the following aspects should be considered when manufacturing electrodes for supercapacitor applications: • Electrode materials may have a large surface area, porosity, and conductivity to achieve excellent electrochemical performance.

[0044] • Electrolytes may permeate into the porous surface of the electrode material.

[0045] • Uses highly conductive materials to reduce resistance and allow for high power transmission.

[0046] • Environmentally friendly and non-toxic electrodes.

[0047] • Large-area electrodes can be manufactured using simple, low-cost, and industry-scalable methods.

[0048] The energy density (E) and power density (P) of a supercapacitor are calculated using formulas (1) and (2). E=½CV 2 (1) P=V 2 / 4R, (2) Where C is the DC capacitance, V is the voltage, and R is the resistance. According to this formula, embodiments of the present invention focus on increasing the energy density of the supercapacitor by increasing its capacitance and operating voltage.

[0049] Therefore, taking into account the above aspects, the materials and dimensions selected according to embodiments of the present invention relate to the manufacture of improved hybrid supercapacitors.

[0050] Now for reference Figure 1A , Figure 1AThis is an illustration of a symmetrical supercapacitor according to some embodiments of the present invention. The supercapacitor 100 may include 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 are mirror-symmetrical from both sides of the electrolyte 20, as shown in the figure.

[0051] In some embodiments, each of electrodes 10A and 10B may comprise a carbon-based material 12 and a metal chalcogenide nanostructure 14, wherein the metal includes Cu, Va, Ni, Co, Ag, Fe, Mn, Sn, and any combination thereof, and the chalcogenide includes Te, Se, and S. For example, the carbon substrate 12 may be attached to the metal chalcogenide nanolayer (or nanosheet) 14. For example, functionalized MWCNTs may be used to form the carbon substrate 12. In some embodiments, the metal chalcogenide compound layer 14 may comprise at least one of the following: SnSe nanostructure, CuSe nanostructure, CuS nanostructure, CuTe nanostructure, SnTe nanostructure, SnS nanostructure, AgS nanostructure, AgSe nanostructure, AgTe nanostructure, NiS nanostructure, NiSe nanostructure, NiTe nanostructure, nanostructure, CuSnS nanostructure, CuSnSe nanostructure, CuSnTe nanostructure, nanostructure, NiSnS nanostructure, NiSnSe nanostructure, NiSnTe nanostructure, nanostructure, CoSnS nanostructure, CoSnSe nanostructure, CoSnTe nanostructure, nanostructure, AgSnS nanostructure, AgSnSe nanostructure, AgSnTe nanostructure, etc. (given by other metal chalcogenides).

[0052] In some embodiments, the metal chalcogenide compound 14 has the chemical formula MSnX, where M is selected from Cu, Ag, Co, Ni, etc., and X is selected from Te, Se, and S.

[0053] In some embodiments, the mass load of layer 12 is between 0.1 mg / cm². 2 Up to 20 mg / cm 2 Between, for example, 0.15 mg / cm 2 0.3 mg / cm 2 0.5 mg / cm 2 1mg / cm 2 2mg / cm 2 5mg / cm 2 7mg / cm 2 10mg / cm 2 15mg / cm 2 20mg / cm 2And any value in between. In some embodiments, the mass load of layer 14 is between 0.1 mg / cm². 2 Up to 20.0 mg / cm 2 Between, for example, 0.1 mg / cm 2 0.3 mg / cm 2 0.5 mg / cm 2 1mg / cm 2 2mg / cm 2 5mg / cm 2 7mg / cm 2 10mg / cm 2 15mg / cm 2 20mg / cm 2 And any value in between.

[0054] In some embodiments, the carbon-based material can be a functionalized carbon-based material, such as functionalized SWCNT, DWCNT, MWCNT, carbon nanotube pearl powder, carbon black, graphite powder, allotropes of graphene, activated carbon black, etc.

[0055] In some embodiments, the first layer 12 may include oriented SWCNTs, DWCNTs, and MWCNTs. In this case, the longitudinal axes of the SWCNTs, DWCNTs, and MWCNTs are substantially parallel to the surface of the second layer 14.

[0056] In some embodiments, each of the first electrode 10A and the second electrode 10B may comprise a composite material containing a mixture of nanostructures of carbon-based materials and metal chalcogenide compounds. For example, electrodes 10A and 10B may comprise a mixture of SnS nanoflowers and MWCNTs or carbon nanoparticles of pearl powder.

[0057] In some embodiments, the weight ratio between the carbon-based material and the nanostructure of the metal chalcogenide mixture is between 1:1 and 1:4, such as 1:1.5, 1:2, 1:2.5, 1:3, 1:35, 1:14, and any value in between.

[0058] In some embodiments, the electrolyte 20 may be placed between electrodes 10A and 10B. For example, when electrodes 10A and 10B comprise a metal chalcogenide compound layer 14, the electrolyte 20 is located between layers 14, as shown in the figure.

[0059] In some embodiments, when a composite material is included, each of the first and second electrodes 10A and 10B may further include additives, such as polyvinylidene fluoride (PVDF).

[0060] In some embodiments, the electrolyte 20 may include aqueous solutions of KOH, NaOH, NaCl, KCl, Na₂SO₃, Na₂SO₄, NaClO₄, TBAPF₄, TPAPF₆, TEAPF₆, K₂SO₃, TEAPF₄, LiClO₄, LiCl, LiOH, Li₂SO₄, etc. In this case, the supercapacitor 100 may also include a separator (not shown). In some embodiments, the separator may be made of cellulose paper or a gel polymer electrolyte membrane.

[0061] In some embodiments, the electrolyte 20 may include an organic gel, including polyvinyl alcohol (PVA), n-methyl-2-pyrrolidone (NMP), cellulose powder, acetonitrile, sulfonated tetrafluoroethylene vinyl fluoropolymer copolymer (Nafion), carboxymethyl cellulose (CMC), etc. The gel can be mixed and therefore may include one ion selected from KOH, NaOH, NaCl, KCl, Na2SO3, Na2SO4, NaClO4, TBAPF4, TPAPF6, TEAPF6, K2SO3, TEAPF4, LiClO4, LiCl, LiOH, Li2SO4, etc.

[0062] In some embodiments, the supercapacitor 100 may also include two current collectors 30, each current collector 30 being connected to the surface of the first electrode 10A or the second electrode 10B that is not facing the electrolyte 20. The current collectors 30 may include any metal sheet, such as stainless steel foil / mesh, copper foil, nickel foam / foam, aluminum foil / mesh, or carbon cloth / foam.

[0063] Now for reference Figure 1B , Figure 1B This is an illustration of an asymmetric supercapacitor according to some embodiments of the present invention. The asymmetric supercapacitor 200 may include a first electrode 110, a second electrode 120, and an electrolyte 20. In the asymmetric supercapacitor, the first electrode 110 differs from the second electrode 120 in that it is at least one of a carbon-based material and / or a nanostructure of a metal chalcogenide compound.

[0064] Electrolyte 20 may be substantially the same as that of supercapacitor 100. Supercapacitor 200 may also include current collector 30, which is substantially similar to current collector 30 of supercapacitor 100.

[0065] In some embodiments, the first electrode 110 may include a first carbon-based material 112 and a first nanostructure 114 of a metal chalcogenide compound. In this case, the first electrode 110 may be a positive electrode.

[0066] In some embodiments, the second electrode 120 may comprise only the second carbon-based material 122. In this case, the second electrode 120 may be a negative electrode. In some embodiments, the second electrode 120 may also comprise a second nanostructure of a metal chalcogenide compound.

[0067] 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 includes single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanotube pearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, activated carbon black, etc.

[0068] In some embodiments, the metal chalcogenide compound 114 may include metals selected from Cu and Sn, and chalcogenides selected from Te, Se and S.

[0069] In some embodiments, the metal chalcogenide 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, nanostructures, CuSnS nanostructures, CuSnSe nanostructures, CuSnTe nanostructures, nanostructures, NiSnS nanostructures, NiSnSe nanostructures, NiSnTe nanostructures, nanostructures, CoSnS nanostructures, CoSnSe nanostructures, CoSnTe nanostructures, nanostructures, AgSnS nanostructures, AgSnSe nanostructures, AgSnTe nanostructures, etc. (given by other metal chalcogenides).

[0070] In some embodiments, the metal chalcogenide compound 14 has the chemical formula MSnX, where M is selected from Cu, Ag, Co, Ni, etc., and X is selected from Te, Se, and S.

[0071] In some embodiments, the first layer 112 may include oriented SWCNTs, DWCNTs, and MWCNTs. In this case, the longitudinal axes of the SWCNTs, DWCNTs, and MWCNTs are parallel to the surface of the second layer 114.

[0072] In some embodiments, the mass load of layer 112 is between 0.1 mg / cm². 2 Up to 20 mg / cm 2 Between, for example, 0.15 mg / cm 2 0.3 mg / cm 20.5 mg / cm 2 1mg / cm 2 1.5 mg / cm 2 2mg / cm 2 5mg / cm 2 7mg / cm 2 10mg / cm 2 15mg / cm 2 20mg / cm 2 And any value in between. In some embodiments, the mass load of layer 114 is between 0.1 mg / cm². 2 Up to 20.0 mg / cm 2 Between, for example, 0.1 mg / cm 2 0.3 mg / cm 2 0.5 mg / cm 2 1mg / cm 2 1.5 mg / cm 2 5mg / cm 2 7mg / cm 2 10mg / cm 2 15mg / cm 2 20mg / cm 2 And any value in between.

[0073] In some embodiments, the first electrode 110 may include a composite material comprising a mixture of a carbon-based material and a nanostructure of a metal chalcogenide compound. For example, electrode 110 may include a mixture of SnS nanoflowers and MWCNTs or carbon nanoparticles.

[0074] In some embodiments, the weight ratio between the carbon-based material and the nanostructure of the mixed compound of metal chalcogenides is between 1:1 and 1:4, such as 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 and any value between therewith.

[0075] In some embodiments, when a composite material is included, the first electrode 110 may also include additives, such as polyvinylidene fluoride (PVDF).

[0076] In some embodiments, electrolyte 20 may be placed between electrodes 110 and 120. For example, when electrode 110 comprises a metal chalcogenide compound layer 114, electrolyte 20 is located between layer 114 and electrode 120, as shown in the figure.

[0077] In some embodiments, supercapacitor 100 and / or supercapacitor 200 may further include first and second conductive layers 35. The first and second conductive layers 35 may be connected from one side to a first current collector 30 or a second current collector 20, and to a first carbon-based material 12 and 112 or a second carbon-based material 12 or 122, respectively. In some embodiments, the conductive layer 35 may comprise a mixture of 70 to 90 wt.% graphite, 20 to 5 wt.% MWCNT, and a binder (e.g., a conductive binder (e.g., PVDF, CMC, etc.)). In some embodiments, the mass load of each of the first and second conductive layers 35 may be 0.1 mg / cm². 2 Up to 20.0 mg / cm 2 between.

[0078] In some embodiments, supercapacitor 100 and / or supercapacitor 200 may not include conductive layer 35.

[0079] Now for reference Figure 2 , Figure 2 This is a method for manufacturing electrodes for a supercapacitor according to some embodiments of the present invention. In step 210, a nanostructure of a metal chalcogenide compound is synthesized. In some embodiments, the metal includes Cu, Ag, Ni, Co, Sn, and any combination thereof, and the chalcogenide is selected from Te, Se, and S. Some non-limiting examples of the synthesis of metal chalcogenide compounds are given below in the Examples section.

[0080] In step 220, a first layer comprising 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 may be deposited on the substrate by at least one of spraying, printing, application, 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 nanotube pearl powder, functionalized carbon, carbon black, graphite powder, allotropes of graphene, and activated carbon black, etc.

[0081] In step 230, a second layer comprising a nanostructure containing a metal chalcogenide compound may be deposited on one side of the first layer. The nanostructure 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, application, etc.

[0082] In some embodiments, steps 220 and 230 may be combined to form a monolayer comprising both a carbon-based material and a metal chalcogenide compound. In some embodiments, the carbon-based material and the metal chalcogenide compound may be mixed and deposited on the carbon-based material layer by at least one of spraying, printing, application, etc.

[0083] In some embodiments, the method may also include depositing electrodes on a current collector, such as current collector 30.

[0084] In some embodiments, the method may include applying a first conductive layer (e.g., layer 35) over a current collector (e.g., current collector 30). The method may include mixing 70 to 90 wt.% graphite, 20 to 5 wt.% MWCNT with a binder (e.g., PVDF, CMC, etc.) and a solvent (e.g., NMP, water, etc.). The mixture is then deposited onto a surface of the current collector by at least spraying, printing, application, or other methods.

[0085] 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, such as Figure 1A and 1B As shown.

[0086] Example Synthesis of SnSe nanosheets A one-pot thermal synthesis route was adopted to complete the solution treatment and phase-controlled two-dimensional (2D) SnSe nanosheet fabrication. SnCl4:5H2O, SeO2, 1-10Phen, and OAM were synthesized in a one-pot thermal synthesis under nitrogen (N2) atmosphere. The novel features of this synthetic route are: (1) the use of an inexpensive and non-toxic selenium precursor (SeO2) instead of expensive, toxic, and complex selenium sources such as sodium selenosulfate. (2) the preparation of single-phase and single-crystal SnSe by controlling reaction parameters. (3) the synthetic route facilitates the optimization of SnSe 2D morphology. In short, 0.05 M SnCl4:5H2O, 0.05 M SeO2, and 0.05 M –1-10phenanthroline were mixed in 20 ml of OAM. Since selenium is insoluble in water, OAM was used as a solvent in this case. 1-10Phen played an important role in achieving single-phase SnSe as a capping agent and reducing agent. The mixture was stirred for 15 minutes in a nitrogen (N2) atmosphere at a flow rate of 0.5 L / min. The three-necked flask was then heated to 120 °C using the same N2 flow rate. Once 120 °C was reached, the flow rate was increased to 1 L / min for 10 minutes. The solution was then heated again 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 purified by repeated centrifugation at 4500 rpm with the addition of ethanol and acetone.

[0087] Now for reference Figure 3 , Figure 3 This is an X-ray diffraction pattern of 2D SnSe nanosheets according to some embodiments of the present invention. The pattern was obtained from synthesized SnSe. Further SEM analysis confirmed the surface morphology of the depicted 0.05 M concentration 2D SnSe nanosheets, such as... Figure 4 As shown.

[0088] Synthesis of CuSe nanostructures Copper(II) chloride dihydrate (CuCl2·2H2O, 99%, Fisher chemicals), selenium dioxide (SeO2, 99.4%), 1-10 phenanthroline (C 12 H8N2, 99%) and oleylamine (C 18 H 37 N, 80-90%, Acros organics) are used as is in the synthesis without further purification, such as Figure 5Schematic. CuSe nanocrystals were synthesized using a simple one-pot chemical route with oleylamine as the solvent. In a typical synthesis, CuCl2·2H2O, SeO2 (molar concentrations of, for example, 0.02 M, 0.05 M, 0.1 M, and 0.15 M), and 1–10 phenanthroline (0.1 M) were dissolved in 20 mL of oleylamine under magnetic stirring to form a precursor solution at room temperature under a N2 atmosphere for 15 minutes, which was then transferred to a three-necked flask. The reaction solution was heated to 90 °C and held for 10 minutes. The temperature was then increased to 180 °C and held for 1 hour. After natural cooling to room temperature, the final product was collected by centrifugation and washed several times with ethanol and acetone.

[0089] Now for reference Figure 6 , Figure 6 These are SEM images of CuSe according to some embodiments of the present invention. Figure 6 (ah) shows SEM images of the copper selenide structures obtained from reactions with concentrations of 0.02, 0.05, 0.1, and 0.15 molar. (as shown in the image) Figure 6 As shown in (a, b, c, g, h), CuSe crystals grow in an irregular pattern. Hexagonal and plate-like nanostructures are shown... Figure 6 As shown in (d, e), the thickness of the hexagonal plate ranges from 40 nm to 70 nm. A wide range of hexagonal edge lengths was observed, varying between 89 nm and 235 nm.

[0090] Now for reference Figure 7A , Figure 7A The XRD patterns of CuSe according to some embodiments of the present invention are shown. The crystal structure and chemical composition of copper selenide powder were confirmed by XRD. Figure 7A (ad) shows typical XRD patterns of copper selenide synthesized at concentrations of 0.02 M, 0.05 M, 0.1 M, and 1.15 M, demonstrating the polycrystalline nature of the material. The sharp, narrow peaks detected in the XRD pattern of the 0.02 M concentration sample can be attributed to the mixed phase of copper selenide. Figure 7A (a)). Peak position and intensity match the standard data for hexagonal CuSe (denoted by @), cubic CuSe2 (denoted by *), and klockmannite CuSe (JCPDS No. 01-086-1240) (indicated by @).

[0091] Figure 7A (b) shows that the XRD pattern of 0.05 M copper selenide can be used as an indicator of mixed phases. The peak positions and intensities are matched with standard data for hexagonal CuSe indicated by @, cubic CuSe2 indicated by *, and copper selenide CuSe indicated by @.

[0092] In XRD patterns ( Figure 7A In the sample at a concentration of 0.1 M, the sharp, narrow peaks observed can be indexed as the (101), (102), (103), (006), (104), (105), (106), (008), (110), (108), (201), (203), and (208) crystal planes of hexagonal CuSe with the selenochromium phase. The peak positions and intensities match well with the standard data for hexagonal CuSe.

[0093] Figure 7A (d) shows the XRD pattern of the 0.15 M concentration sample as an indicator of the mixed phase. Peak positions and intensities are compared with those of hexagonal CuSe (indicated by @), cubic CuSe2 (indicated by *), and Cu (indicated by *). 0.87 The data matches the standard data of SE.

[0094] XRD analysis of the sample prepared at a concentration of 0.1 M confirmed the presence of a pure copper selenide phase in CuSe.

[0095] Now for reference Figure 7B , Figure 7B Transmission electron microscopy (TEM), high-resolution (HR) TEM, selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS) are shown. Figure 7B (a) and (b) show typical TEM and high-resolution (HR) TEM images of a single CuSe nanosheet, revealing hexagonal nanosheets with well-resolution 2D lattice fringes. The fringe spacing value is 0.341 nm, which matches well with the interplanar spacing d of the (100) crystal plane of CuSe. SAED spectra ( Figure 7B (c) also suggests a single-crystal hexagonal structure. Furthermore, energy-dispersive X-ray spectroscopy (EDS) ( Figure 7B (d) shows two strong peaks for Cu and Se. Quantitative EDS analysis indicates that the atomic ratio of Cu to Se is close to the inherent 1:1 stoichiometry, suggesting that CuSe-NS is of uniform purity.

[0096] Now for reference Figure 7C , Figure 7C This shows the nitrogen adsorption / desorption isotherms and pore size distribution of CuSe nanosheets, as well as the BJH pore size distribution curve (inset). The nitrogen desorption-desorption isotherms were obtained using the multi-point BET method. Figure 9 The surface area and pore size of CuSe nanostructures were obtained. The pore size of the CuSe nanosheets was found to be 5.13 nm, and the specific surface area was 10.90 m². 2 / g.

[0097] Electrochemical performance studies of CuSe nanostructured supercapacitors were conducted under three electrode configurations: An impregnation-drying method was used to deposit CuSe nanostructures on an SS substrate. 10 mg of synthesized CuSe powder (0.1 M) was dissolved in 10 mL of ethanol. The SS substrate (1 x 1 cm) was immersed in the prepared CuSe solution for 20 seconds to adsorb CuSe onto the SS substrate, followed by IR heating and drying. This process was repeated 20 times to obtain optimal CuSe coverage on the SS substrate. The mass loading was calculated by weighing the substrate before and after deposition and subtracting the weights (weight difference method).

[0098] Synthesis of SnS nanostructures Tin(II) chloride dihydrate (SnCl2:2H2O>=97%), sublimed sulfur (99.5%, Acros organics), and oleylamine (C 18 H 37 (N, 80-90%) Use as is, no further processing required.

[0099] The SnS flower-like nanostructures were synthesized using a simple and economical one-pot heating route. In the typical synthesis, SnCl2:2H2O (0.05M) and sulfur (0.1M) were used as the tin source and sulfur itself; oleylamine (10 ml) was used as the solvent. Initially, sulfur was added to OA and stirred until the solution turned orange, or until the sulfur was completely dissolved in OA. Subsequently, SnCl2:2H2O was added to the solvent and stirred for 10 minutes under N2 atmosphere. The solution was then heated to 120°C and held at this temperature for 20 minutes. Again, the temperature of the three-necked flask was heated to 180°C and held at this temperature for 1 hour. Once naturally cooled, the final product was collected by centrifugation and washed 4 to 5 times with ethanol.

[0100] Now for reference Figure 8A , Figure 8A The XRD patterns of SnS according to some embodiments of the present invention are shown. The XRD patterns show that the structural features of the synthesized flower-like SnS nanostructures are as follows: Figure 8A As shown. XRD patterns were recorded in 20 o Up to 80 o Within the scanning angle range. All observed diffraction peaks of the synthetic nanomaterials can be labeled as orthorhombic SnSe with lattice parameters a=5.6730, b=5.7500 and c=11.7600 Å (JCPDS No. 01-079-2193).

[0101] Now for reference Figure 8B , Figure 8BSEM images of SnS nanostructures according to some embodiments of the present invention are shown. SEM analysis confirmed the surface morphology of the 3D flower-like SnS nanostructures. The SEM images of the 3D flower-like SnS nanostructures were also confirmed by corresponding EDS (not shown). Low-magnification SEM images ( Figure 8A -a) Depicts a 3D flower-like SnS nanostructure. Figure 8A The high-magnification image shown in -b reveals a large coverage of the flower-like nanostructure. The average thickness of the 3D flower-like SnS nanostructure is 14 nm. The EDS spectrum shown clearly consists of peaks for Sn and S, clearly indicating the formation of the tin sulfide phase. Finally, the EDS analysis is in high agreement with the XRD results, confirming the successful deposition of the 3D flower-like SnS nanostructure via the proposed chemical route.

[0102] Functionalization of MWCNT 95% pure MWCNTs (5-15 μm in length, 15-20 nm in outer diameter) were refluxed with H2O2 at 90 °C for 48 hours to anchor oxygen-containing functional groups and remove amorphous carbon derivatives. The residues were repeatedly washed 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 Triton X-100 surfactant with 25 mL of DDW (Tx-100:DDW:1:100) for 1 hour.

[0103] Cyclic voltammetry measurement The deposited CuSe had a mass loading of 0.2 mg and was examined in various electrolytes (such as NaOH, KOH, NaCl, LiCl, and Na2SO3) at a fixed concentration of 0.5 M and a scan rate of 100 mV / s. In a three-electrode cell configuration, the CuSe electrode was used as the working electrode (WE), Ag / AgCl as the reference electrode (RE), and a platinum wire as the counter electrode (CE). The unit area (cm²) of immersion in different electrolytes was estimated from the CV curves according to the following formula (1). 2 ) Specific capacitance of CuSe electrode.

[0104] (1) Wherein, "Cs" represents the specific capacitance (Fg) -1 "V" represents the potential scan rate (mVs) -1 (Vc-Va) is the operating potential window, "I" is the current response (mA), and "m" is the deposition mass of the sample electrode.

[0105] Now for reference Figure 9 , Figure 9The CV plot recorded at a scan rate of 100 mV / s is shown using formula (1). Figure 9 (a) Shows the CV curves for different electrolytes at a concentration of 0.5 M. Figure 9 (b) Display the corresponding capacitance diagram.

[0106] Table 1 shows the specific capacitance and areal capacitance of CuSe with different electrolytes.

[0107] Table 1

[0108] The CV curves show that, compared with other electrolytes, the CuSe electrode exhibits good current distribution, high CV area, and high specific capacitance in NaOH electrolyte.

[0109] Therefore, NaOH electrolyte was selected, and concentration optimization was performed using CV. The NaOH concentration was increased from 0.5 M to 3 M in 0.5 M increments, and the corresponding CV curves were recorded. Analysis was conducted at a fixed mass loading (0.2 mg) and a scan rate of 100 mV / s. Figure 10 As shown.

[0110] Figure 10 (a) shows the CV curves for different concentrations of NaOH. Figure 10 (b) shows the corresponding capacitance diagram. The calculated specific capacitance values ​​are given in Table 2 below.

[0111] Table 2

[0112] In some embodiments, an increase in capacitance was observed after changes in electrolyte concentration. The highest capacitance was observed at two different concentrations (i.e., 1.5 M and 2.5 M NaOH). However, the current distribution at 2.5 M NaOH was relatively better than that at 1.5 M NaOH, which would be beneficial for device fabrication. Mass load variations were performed using the optimized electrolyte concentration (i.e., 2.5 M NaOH). CV was performed for different mass loads and... Figure 11 As shown in the image.

[0113] Figure 11 (a) shows the CV curves at 100 mV / s in 2.5 M NaOH under different CuSe mass loadings. Figure 11 (b) shows the corresponding capacitance diagram.

[0114] The calculated specific capacitance values ​​are given in Table 3. Table 3 shows the specific capacitance and areal capacitance values ​​of CuSe under different mass loads.

[0115] Table 3

[0116] Now for reference Figure 12 , Figure 12 Electrochemical measurements of CuSe mass loading (0.45 mg) and NaOH molar concentration (2.5 M) on SS are shown. Various scan rate CV curves for CuSe were examined, and... Figure 12 As shown in (a), the specific capacitance decreases as the scan rate increases from 2 mV / s to 100 mV / s. Figure 12 (b) This may be due to the time constraint during the electrolytic interaction process. It was found that the maximum capacitance of the CuSe nanosheets was 718.04 F / g (323.12 mF / cm²) for a scan rate of 2 mV / s. 2 ).

[0117] Figure 12 Electrochemical characterization of 0.45 mg CuSe nanosheets on an SS substrate is shown (a, b). CV curves of CuSe nanosheets at different scan rates and their corresponding capacitances (in F / g and mF / cm) are also shown. 2 (c, d) Constant current charge-discharge (GCD) curves at different current densities and their corresponding capacitances (units are F / g and mF / cm). 2 ).

[0118] All calculated capacitance values ​​are shown in Table 4.

[0119] Table 4 shows the specific capacitance and areal capacitance of CuSe at different scan rates.

[0120]

[0121] like Figure 12 As shown in (c), the material rate capability of the device according to some embodiments of the present invention was examined / measured using constant current charge-discharge (GCD) at different current densities from 4 A / g to 1 A / g. The highest capacitance at a current density of 1 A / g was found to be 272.34 F / g (122.56 mF / cm²). 2 The capacitance values ​​under different current densities were calculated and are shown in Table 5.

[0122] Table 5 includes the specific capacitance and areal capacitance of CuSe under different current densities.

[0123]

[0124] Electrochemical impedance spectroscopy (EIS) studies EIS evaluation is one of the most important factors in supercapacitor electrode evaluation. To explore the sources of conductivity, ion diffusion, charge transfer mechanisms, and capacitive behavior, electrochemical impedance spectroscopy (EIS) tests using Nyquist plots (Z'v – “Z”) were performed in the frequency range of 1 Hz to 100 kHz (a). The two distinct parts of the Nyquist plot, such as the half-curvature and linear rise in the high-frequency and low-frequency regions, clearly demonstrate the electrochemical characteristics of the device. Figure 13 As shown in (a), a semi-quantitative fitting was performed using analog circuit simulation with R(Q(R(QR)) to check the impedance results. Figure 13 (b)).

[0125] In the higher frequency region, the intersection of the semicircles reflects the internal resistance (Rs), which is formed by the combination of contact resistance at the material interface, substrate internal resistance, and electrolyte ion resistance. The diameter of the semicircle determines the charge transfer resistance (Rct) involved in the electrochemical process during electrochemical operation. The constant phase element (CPE, Q) consists of two parts: (i) the Yo-admittance (S.sn) and (ii) a fractional element n ranging from 0 to 1. If n is close to 1, the electrode appears to behave like a perfect capacitor. Figure 13 (a) shows the Nyquist plot of CuSe fitted to the equivalent circuit R(Q(R(QR))), where black data represents measured data and red data represents fitted (calculated) data. Figure 13 The minimum chi-square value was shown to be 10. -4 A good fit on the order of magnitude. The fitted circuit showed 0.75 Ohm·cm. 2 The resistance of the small solution (Rs) is 161.90 Ohm·cm. 2 Charge transfer resistance (R) ct ).

[0126] Figure 13 (c) and (d) show Bode plots of phase angle and capacitance versus frequency. From Figure 13 (c) The maximum phase angle value displayed by the electrodes is 64.63°. O For an ideal capacitor, it is 90. O This means that the electrodes exhibit capacitive properties. A key variable is the relaxation time constant (τ) of the supercapacitor electrodes. o =1 / f o f o =characteristic frequency). The low relaxation time indicates that electrolyte ions have reached the film, the electrochemical cell has reached its maximum capacitance, and it is still charging rapidly. This indicates that rapid charge diffusion occurred between reversible insertion / extraction operations, and the estimated τ o For 0.2 seconds ( Figure 13(c)). Furthermore, at a phase angle of -45°, τ o It is calculated based on the frequency and phase angle diagram. Figure 13 (c) because the resistance and capacitance are the same. The relaxation time of the electrode is 0.2 seconds, which represents the rate at which the accumulated charge can be successfully distributed. The calculated τ o For 0.2 s ( Figure 13 (d) indicates that rapid charge diffusion occurred between the reversible insertion / extraction processes.

[0127] Electrochemical stability Since stability affects the supercapacitor performance of the electrode, the stability (capacitance retention) of the electrode was studied under 3500 CV cycles at a scan of 100 mV / s. Figure 14 The relationship between capacitance retention and CV cycling is shown, with CV cycling illustrated in the inset. A very good capacitance retention of approximately 96.41% was observed from stability measurements. Therefore, Figure 14 The electrochemical stability of the CuSe nanosheet electrode was demonstrated after 3500 repeated CV cycles at 100 mV / s.

[0128] 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), Carbene Black SUPERP (99%) / SUPERP®, BLACK PEARLS®, VULCAN® (99%) / AC(TOB), L-ascorbic acid (C6H8O6, 99%), and sodium borohydride (NaBH4, 99%). All materials were AR and used as is without further processing. Water purified using a Milli-Q system with a resistivity >15 MΩ·cm was used throughout the experiment. All the above materials were used to synthesize CuSe / SnSe / CuSe@carbon black / SnSe@carbon black, respectively. A modified Creighton-type process was used for synthesis. A metal cation / metal alloy solution (50 mL, 0.03 M M) was prepared in flask A when M = Cu, Sn, Co, Ni, or Ag. n+An aqueous solution of selenium powder (0.02 M) was prepared in flask A. Then, 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 selenium 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 without heating, while vigorously stirring. The mixture was cooled to room temperature while stirring for 2 hours. Next, the mixture was centrifuged to obtain a black precipitate. The precipitate was washed several times with water, then washed with alcohol. Finally, the black nanostructures were dried in an oven at 85 °C for at least 2 hours, preferably overnight.

[0129] Additional combinations of metal cations were tested to generate other chalcogenide materials. The effects on the nanostructures were investigated using various reducing agents, such as NaBH4, NaOH, and ascorbic acid, and at various concentrations, such as 0.03 M, 0.06 M, and 0.12 M.

[0130] 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 Creighton-type process was used for synthesis. Aqueous solutions (50 mL, 0.03 M M) of metal cations / metal alloys of M=Cu, Sn, or Ag were prepared in flask A. n+ Then, solid L-ascorbic acid (0.02M) was added to the solution. The solution in flask A was vigorously stirred and heated to 70-80°C (solution A). Simultaneously, an aqueous solution of selenium powder (50 mL, 0.03M) 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, 0.06M) was added. After the heating step, solution A was rapidly added to solution B without heating, while vigorously stirring. The mixture was cooled to room temperature while stirring for 2 hours. Next, the mixture 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.

[0131] Additional combinations of metal cations were tested to generate alloy nanostructures such as Cu-Sn, Ag-Sn, etc. In this case, aqueous mixtures of cations were used at the same concentrations as described above, following the same procedure. Furthermore, the effects on the nanostructures were tested using different reducing agents, such as NaOH and ascorbic acid, and at various concentrations, such as 0.03M, 0.06M, and 0.12M.

[0132] Now for reference Figure 15 , Figure 15 HR-SEM images of some of the aforementioned metal chalcogenide nanostructures are shown. According to some embodiments of the present invention, Figure 15 The images include (a) low-magnification CuSe on the ribbon surface, (b) high-magnification CuSe on the grid surface, (c) low-magnification CuSnSe on the ribbon surface, (d) high-magnification CuSnSe on the grid surface, (e) low-magnification SnSe on the ribbon surface, and (f) high-magnification SnSe on the grid surface.

[0133] Unless explicitly stated otherwise, the methods described herein are not bound by a particular order or sequence. Furthermore, all formulas described herein are intended as examples only, and other or different formulas may be used. Additionally, some of the described method implementations or elements thereof may occur or be performed at the same time.

[0134] While certain features of the invention have been described and illustrated herein, many modifications, substitutions, alterations, and equivalents may be made by those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all modifications and alterations consistent with the true spirit of the invention.

[0135] Various implementations have been proposed. Of course, each of these implementations may include features from other presented implementations, and implementations not specifically described may include the various features described herein.

Claims

1. A supercapacitor comprising: a first electrode comprising a first carbon-based material and a first nanostructure of a metal chalcogenide, 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; an electrolyte; and a second electrode selected from: (i) a second carbon-based material; and (ii) a second nanostructure of a metal chalcogenide and the second carbon-based material, 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.

2. The ultracapacitor of claim 1, wherein the first electrode comprises: a first layer comprising the carbon-based material and a second layer comprising the nanostructure of the metal chalcogenide.

3. The ultracapacitor of claim 2, wherein the first layer has a mass loading between 0.1 mg / cm 2 and 0.3 mg / cm 2 and the second layer has a mass loading between 0.2 mg / cm 2 and 10.0 mg / cm 2 .

4. The ultracapacitor of claim 1, wherein the first electrode comprises: a composite material comprising a mixture of the carbon-based material and the nanostructure of the metal chalcogenide.

5. The supercapacitor of any one of claims 1 to 4, further comprising: a first current collector; a first conductive layer connected from one side to the first current collector and the first carbon-based material; a second current collector; and a second conductive layer connected from one side to the second current collector and the second carbon-based material.

6. The supercapacitor of claim 5, wherein the first and second conductive layers comprise a mixture of 70 to 90 wt.% of graphite, 20 to 5 wt.% of multi-walled carbon nanotubes (MWCNTs), and a binder.

7. The supercapacitor of any one of claims 1 to 6, wherein the nanostructure of the metal chalcogenide comprises a morphology selected from nanoparticles, nanotubes, nanospheres, nanosheets, nanowires, and nanoflowers.

8. The supercapacitor of 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 of claim 8, wherein the first layer comprises oriented SWCNTs, DWCNTs, and MWCNTs that are produced parallel to a surface of the second layer.

10. The supercapacitor of any one of claims 1 to 9, wherein the electrolyte comprises at least one of KOH, NaOH, NaCl, KCl, Na2SO3, Na2SO4, NaClO4, TBABF4, TBAPF6, TEAPF6, K2SO3, TEABF4, LiClO4, LiCl, LiOH, and Li2SO4.

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

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

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

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

16. The supercapacitor of claim 1, further comprising two current collectors, each connected to a surface of the first or second electrode that does not face the electrolyte.

17. A supercapacitor, comprising: a first electrode; an electrolyte; and a second electrode, wherein each of the first and second electrodes comprises a carbon-based material, and nanostructures of a metal chalcogenide, wherein 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. a first layer comprising the carbon-based material and a second layer comprising the nanostructures of the metal chalcogenide.

18. The ultracapacitor of claim 17, wherein each of the first electrode and the second electrode comprises: a composite material comprising a mixture of the carbon-based material and the nanostructures of the metal chalcogenide.

19. The ultracapacitor of claim 18, wherein the first layer has a mass loading between 0.1 mg / cm 2 and 20.0 mg / cm 2 and the second layer has a mass loading between 0.1 mg / cm 2 and 20.0 mg / m 2 .

20. The ultracapacitor of claim 19, wherein each of the first electrode and the second electrode comprises:

21. The supercapacitor of claim 20, wherein the weight ratio between the carbon-based material and the nanostructures of the metal chalcogenide mixture is between 1:1 and 1:

4.

23. The supercapacitor of claims 17-21, wherein the nanostructures have a pore size between 4 and 6 nm.

22. The supercapacitor of claims 17-21, wherein the nanostructure has a pore size greater than 9 m 2 / g.

24. A method of manufacturing an electrode for a supercapacitor, comprising: synthesizing nanostructures of a metal chalcogenide, 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; forming a first layer comprising a carbon-based material; and depositing a second layer comprising nanostructures of a metal chalcogenide on one side of the first layer.

25. The method of 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 of claims 24 and 25, further comprising depositing the electrode on a current collector.

27. The method of claim 26, further comprising depositing a conductive layer on the current collector prior to depositing the electrode. ​ ​ 28. The method of claim 26 or 27, further comprising assembling a supercapacitor using the first electrode of any one of claims 24 and 25, an electrolyte, and a second electrode selected from: (i) a carbon-based material deposited on a current collector; and (ii) the electrode of any one of claims 24 and 25.

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