Active material combined with mxene, cathode active material combined with mxene, secondary battery, and supercapacitor

Abstract

The present invention relates to an active material combined with MXene, a cathode active material combined with MXene, a secondary battery, and a supercapacitor. More specifically, the present invention relates to a cathode active material combined with MXene, as an active material for capacitors or secondary batteries, the material comprising: a cathode active material and two-dimensional MXene bound to the surface of the cathode active material particles, wherein the cathode active material has an R value of about 3 times before a cycle and an R value of about 7 times after a cycle and can remarkably increase discharge capacity, realize a stable capacity retention rate at a high C-rate, and remarkably reduce a capacity reduction rate at a high C (4C) and a long cycle (1000 cyc).

Description

Active materials combined with MXene, cathode active materials combined with MXene, secondary batteries, and supercapacitors

[0001] The present invention relates to an active material combined with MXene, a cathode active material combined with MXene, a secondary battery, and a supercapacitor.

[0002] Conventional metal materials such as copper and silver have high electrical conductivity and have been used in various ways as electrodes and wiring in electronic devices in the semiconductor, display, and information and communication fields. However, their use is limited due to reasons such as relatively high density, high manufacturing cost, difficulty in applying printing process, oxidation and corrosiveness, and insufficient flexibility.

[0003] MXene is a novel nanomaterial with a two-dimensional structure that has high electrical conductivity and excellent solvent dispersibility (mainly in water and hydrophilic solvents). Therefore, research on the development of MXene and MXene / polymer composite materials is very active in the fields of flexible electrodes for printed electronics, thin-film sensors, high-power batteries and supercapacitors, and electromagnetic shielding.

[0004] MXenes are two-dimensional crystalline transition metal carbides. Twenty different MXene compositions have been synthesized so far, including Ti2C, Ti3C2, Nb2C, V2C, Ta4C3, Mo2TiC2, Mo2Ti2C3, and Cr2TiC2. These MXenes exhibit the best electrical conductivity among the recently developed two-dimensional materials.

[0005] MXene can be synthesized from a ceramic material commonly referred to as MAX. MAX has a layered structure of transition metals [e.g., titanium (Ti), niobium (Nb), vanadium (V), tantalum (Ta), molybdenum (Mo), chromium (Cr)], carbon, and Group 14 elements [e.g., aluminum (Al) or silicon (Si)]. By selectively removing only the Group 14 elements through an etching process, a two-dimensional MXene is obtained.

[0006] In most cases up to now, the etching process has been carried out using a strong acid in an aqueous medium, which causes the surface of MXene to have terminal groups such as -OH, =O, -F, and -Cl, and among these, the -OH functional group in particular gives MXene hydrophilic properties.

[0007] MXene synthesized in this way has excellent water dispersibility properties and can be made into a film or sheet using processes such as filtering or bar coating to exhibit excellent electrical conductivity properties.

[0008] However, the existing aqueous etching process using an aqueous solution cannot avoid the problem that water and dissolved oxygen easily oxidize the surface of MXene during the process, causing the formation of metal oxides such as TiO2, and thus reducing the inherent high electrical conductivity of MXene.

[0009] In addition, due to the hydrophilic nature of the MXene surface, MXene, which can only be dispersed in water, has low interaction and bonding strength with other hydrophobic organic materials (polymers, organic substances), so it has been used very restrictively in forming a uniform composite material. In addition, because a long drying process is required at high temperatures to remove water with a high boiling point and heat of vaporization after the solution process, its application to liquid printing processes such as spray coating, spin coating, inkjet printing, bar coating, gravure coating, and web coating has also been limited.

[0010] The present invention relates to an active material combined with MXene, a cathode active material combined with MXene, a secondary battery, and a supercapacitor.

[0011] Conventional metal materials such as copper and silver have high electrical conductivity and have been used in various ways as electrodes and wiring in electronic devices in the semiconductor, display, and information and communication fields. However, their use is limited due to reasons such as relatively high density, high manufacturing cost, difficulty in applying printing process, oxidation and corrosiveness, and insufficient flexibility.

[0012] MXene is a novel nanomaterial with a two-dimensional structure that has high electrical conductivity and excellent solvent dispersibility (mainly in water and hydrophilic solvents). Therefore, research on the development of MXene and MXene / polymer composite materials is very active in the fields of flexible electrodes for printed electronics, thin-film sensors, high-power batteries and supercapacitors, and electromagnetic shielding.

[0013] MXenes are two-dimensional crystalline transition metal carbides. Twenty different MXene compositions have been synthesized so far, including Ti2C, Ti3C2, Nb2C, V2C, Ta4C3, Mo2TiC2, Mo2Ti2C3, and Cr2TiC2. These MXenes exhibit the best electrical conductivity among the recently developed two-dimensional materials.

[0014] MXene can be synthesized from a ceramic material commonly referred to as MAX. MAX has a layered structure of transition metals [e.g., titanium (Ti), niobium (Nb), vanadium (V), tantalum (Ta), molybdenum (Mo), chromium (Cr)], carbon, and Group 14 elements [e.g., aluminum (Al) or silicon (Si)]. By selectively removing only the Group 14 elements through an etching process, a two-dimensional MXene is obtained.

[0015] In most cases up to now, the etching process has been carried out using a strong acid in an aqueous medium, which causes the surface of MXene to have terminal groups such as -OH, =O, -F, and -Cl, and among these, the -OH functional group in particular gives MXene hydrophilic properties.

[0016] MXene synthesized in this way has excellent water dispersibility properties and can be made into a film or sheet using processes such as filtering or bar coating to exhibit excellent electrical conductivity properties.

[0017] However, the existing aqueous etching process using an aqueous solution cannot avoid the problem that water and dissolved oxygen easily oxidize the surface of MXene during the process, causing the formation of metal oxides such as TiO2, and thus reducing the inherent high electrical conductivity of MXene.

[0018] In addition, due to the hydrophilic nature of the MXene surface, MXene, which can only be dispersed in water, has low interaction and bonding strength with other hydrophobic organic materials (polymers, organic substances), so it has been used very restrictively in forming a uniform composite material. In addition, because a long drying process is required at high temperatures to remove water with a high boiling point and heat of vaporization after the solution process, its application to liquid printing processes such as spray coating, spin coating, inkjet printing, bar coating, gravure coating, and web coating has also been limited.

[0019] According to a cathode active material having a surface coated with maxine according to an embodiment of the present invention and a method for manufacturing the same, it has the effect of forming maxine shell on the surface of the cathode active material without using a binder or adhesive in the cathode active material.

[0020] And according to the cathode active material having a MXene coated on the particle surface according to an embodiment of the present invention and the manufacturing method thereof, the R value before the cycle can be reduced by about 3 times, and the R value after the cycle can be reduced by about 7 times, the discharge capacity can be significantly increased, a stable capacity retention rate can be realized at a high C-rate, and the capacity decline rate can be significantly reduced at a high C (4C) and long cycle (1000 cyc) has the effect of being able to be significantly reduced.

[0021] Meanwhile, the effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0022] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0023] Figure 1 is a schematic diagram of a method for coating organic MXene on positive electrode active material (LFP) particles according to an embodiment of the present invention.

[0024] Figure 2 is an electron microscope photograph of positive electrode active material (LFP, LiFePO4) particles.

[0025] Figure 3 is an electron microscope photograph of a cathode active material (MXene / LFP) particle combined with MXene according to an embodiment of the present invention.

[0026] FIG. 4 is an electron microscope photograph of a cathode active material (MXene-EHP / LFP) particle surface-modified with phosphate according to an embodiment of the present invention.

[0027] Figure 5 shows surface electron micrographs and cross-sections of LFP, MXene / LFP, and MXene-EHP / LFP, respectively.

[0028] Figure 6 is an exploded perspective view of a battery manufactured according to an experimental example of the present invention.

[0029] Figures 7 and 8 are graphs of electrochemical impedance (EIS, Electrochemical Impedance Spectroscopy) results for LFP, MXene / LFP, and MXene-EHP / LFP, respectively, according to experimental examples of the present invention.

[0030] Figure 9 is a graph of oxidation potential of LFP, MXene / LFP, and MXene-EHP / LFP according to an experimental example of the present invention.

[0031] Figure 10 is a discharge capacity graph of LFP, MXene / LFP, and MXene-EHP / LFP according to an experimental example of the present invention.

[0032] Figure 11 shows the specific capacity at C-rate of LFP, MXene / LFP, and MXene-EHP / LFP according to an experimental example of the present invention.

[0033] Figure 12 is a graph of the Specific Capacity for 500 cycles at 1C rate of LFP, MXene / LFP, and MXene-EHP / LFP according to an experimental example of the present invention.

[0034] Figure 13 is a graph of Specific Capacity for 1000 cycles at 4C rate of LFP, MXene / LFP, and MXene-EHP / LFP according to an experimental example of the present invention.

[0035] Figure 14 shows discharge capacity graphs of 1, 2, 100, 200, 300, 400, and 500 cycles at 1C rate of LFP, MXene / LFP, and MXene-EHP / LFP according to an experimental example of the present invention.

[0036] Hereinafter, the composition of a secondary battery active material incorporating a maxine according to an embodiment of the present invention will be described in detail. More specifically, the present invention relates to a cathode active material in which a two-dimensional maxine shell is formed.

[0037] According to an embodiment of the present invention, an active material applied to a secondary battery or a supercapacitor has a structure in which a maxine shell is combined and coated.

[0038] MXenes are two-dimensional crystalline transition metal carbides. Twenty different MXene compositions have been synthesized so far, including Ti2C, Ti3C2, Nb2C, V2C, Ta4C3, Mo2TiC2, Mo2Ti2C3, and Cr2TiC2. These MXenes exhibit the best electrical conductivity among the recently developed two-dimensional materials.

[0039] MXene can be synthesized from a ceramic material commonly referred to as MAX. MAX has a layered structure of transition metals [e.g., titanium (Ti), niobium (Nb), vanadium (V), tantalum (Ta), molybdenum (Mo), chromium (Cr)], carbon, and Group 14 elements [e.g., aluminum (Al) or silicon (Si)]. By selectively removing only the Group 14 elements through an etching process, a two-dimensional MXene is obtained.

[0040] According to an embodiment of the present invention, the two-dimensional maxine is M, as described in [Background Technology of the Invention]. n+1 X n A two-dimensional array of crystal cells having an empirical formula of at least one layer, wherein each X is positioned within an octahedral array of a plurality of Ms, wherein M is at least one metal selected from the group consisting of a group IIIB metal, a group IVB metal, a group VB metal, and a group VIB metal.

[0041] Each of the above Xs is one selected from C, N and a combination thereof, and n may be 1, 2 or 3.

[0042] According to an embodiment of the present invention, the two-dimensional MXene is M'2M" n X n+1 A two-dimensional array of crystal cells having an empirical formula of at least one layer, wherein each X is positioned within an octahedral array of a plurality of M' and M", wherein the M' and M" are different metals selected from the group consisting of a Group IIIB metal, a Group IVB metal, a Group VB metal, and a Group VIB metal, wherein each X is C, N, or a combination thereof, and wherein n may be 1 or 2.

[0043]

[0044] A MXene-bonded cathode active material can be manufactured by coating a dispersion of the MXene in a hydrophilic solvent (water) with positive electrode active material particles and stirring the dispersion for a short time in ethanol, and then drying the dispersion.

[0045] In addition, a MXene-bonded cathode active material can be manufactured by coating MXene on a cathode active material such as NCM or iron phosphate and then drying it.

[0046] FIG. 1 is a schematic diagram illustrating a method for coating organic MXene on positive electrode active material (LFP) particles according to an embodiment of the present invention.

[0047] In an embodiment of the present invention, organic MXene, which is surface-modified to be hydrophobic or manufactured using an organic etching method, can be bonded to and coated on positive electrode active material particles. By applying organic MXene, resistance can be further reduced, and compared to non-surface-modified MXene, the bonding strength with the positive electrode active material can be increased, thereby enhancing stability.

[0048] Various embodiments may be applied to the method of surface modification of Maxine, and these embodiments are merely preferred examples and should not limit the scope of the rights to the embodiments.

[0049]

[0050] These organic MXenes can modify the outer surface of the two-dimensional MXene with one selected from the group consisting of compounds containing hydroxyl groups, ionic compounds, azide-based surface-modifying compounds, phosphates having saturated or unsaturated hydrocarbons, and combinations thereof.

[0051] The compound containing a hydroxyl group may be one selected from the group consisting of catechol derivatives, diol compounds, boronic acid compounds, carboxylic acid compounds, sulfonic acid compounds, sulfinic acid compounds, compounds represented by the following chemical formula 1, and combinations thereof.

[0052] [Chemical Formula 1]

[0053]

[0054] By selecting a compound containing the hydroxyl group from the above, the solubility of the compound in an organic solvent can be changed, and the binding force to the surface of the two-dimensional MXene can be improved.

[0055] And the ionic compound is a cation selected from the group consisting of imidazolium compounds, pyridinium compounds, ammonium compounds, phosphinium compounds and combinations thereof; and F - , Cl - , Br - , I - , BF 4- , PF 6- , (CF3SO2)2N - , CF3SO3 - , C2N 3- , CH3SO 3- , CF3BF 3- , C2F5BF 3- , NO 3- , CF3CO 2- , C3H5O 3- and may include one anion selected from a combination thereof.

[0056] And the catechol derivative can be represented by the following chemical formula.

[0057]

[0058] Here, X is selected from at least one of a hydrogen atom (-H), an ester group (-COOR), an amide group (-CONHR), a thioester group (-COSR), a hydrocarbon group (-R), and an ether group (-RO-R'-), and R and R' are each independently selected from a C1-25 aliphatic hydrocarbon and an aromatic hydrocarbon.

[0059] The above R and R' are each independently a saturated or unsaturated cyclic or chain hydrocarbon selected from C1-25 alkyl, C2-25 alkenyl, C2-25 alkynyl, C6-25 aryl, or a heteroatom of 1 to 25 C, N, O or S, or may be unsubstituted or substituted with a functional group of hydroxy or carboxyl.

[0060] And the saturated or unsaturated chain hydrocarbon may or may not contain at least one selected from nitrogen, oxygen, sulfur, sulfinyl and sulfonyl in the middle or side chain of the chain.

[0061]

[0062] And the azide-based surface modification compound may be an azide-based compound having the following chemical formula 2 or 2a.

[0063] [Chemical Formula 2]

[0064]

[0065] [Chemical Formula 2a]

[0066]

[0067] In the above chemical formula 2, Y can be represented by the above chemical formula 2a, in the above chemical formula 2a, R2 is an azide group, R3 is 1 to 4 or more alkyl groups or hydrogen atoms and halogen groups, A1 can be selected from at least one of an ester group (-COOR), an amide group (-CONHR), a thioester group (-COSR), a hydrocarbon group (-R), and an ether group (-RO-R'-), and the R and R' can each be independently selected from a C1-30 aliphatic hydrocarbon and an aromatic hydrocarbon.

[0068] A2 is independently C 1-25 Alkyl, C 2-25 Alkenyl, C 2-25 alkynyl, C 6-25 It may be a saturated or unsaturated chain or cyclic hydrocarbon selected from aryl.

[0069] R1 in the above chemical formula 2 is an atomic bond, substituted or unsubstituted C1 to C 25 Alkyl group, substituted or unsubstituted C4 to C 20 Aryl group, substituted or unsubstituted C5 to C 21 This heteroaryl group and substituted or unsubstituted C1 to C 20 At least one of the alkylamine groups is selected, and n is an integer from 1 to 10.

[0070] The above A2 may be a saturated or unsaturated heterocyclic or chain hydrocarbon each independently containing at least one heteroatom selected from 1 to 25 carbons, nitrogen, oxygen and sulfur, and the saturated or unsaturated heterocyclic or chain hydrocarbon may not contain or contain at least one selected from carbon, nitrogen, oxygen and sulfur in the middle or catalytic portion of each chain.

[0071]

[0072] And the phosphate having a saturated or unsaturated hydrocarbon may be a compound represented by the following chemical formula 3.

[0073] [Chemical Formula 3]

[0074]

[0075] The above A1, A2 or A3 is a hydrogen atom (-H), a C1-25 saturated or unsaturated hydrocarbon, and is selected from at least one of an amide group (-CONHR), a thioester group (-COSR), and an ester group (-RO-R'-).

[0076] The above A1, A2 or A3 are each independently C 1-25 Alkyl, C 2-25 Alkenyl, C 2-25 alkynyl, C 6-25A saturated or unsaturated ring or chain hydrocarbon selected from aryl, or may be unsubstituted or substituted with a functional group of a hydroxyl group or a carboxyl group, or may not contain or contain 1 to 25 heteroatoms of C, N, O or S.

[0077] A1, A2 or A3 are each independently a saturated or unsaturated cyclic or chain hydrocarbon selected from C1-25 alkyl, C2-25 alkenyl, C2-25 alkynyl, C6-25 aryl, or may be unsubstituted or substituted with a functional group of hydroxy or carboxyl, or may not contain or contain 1 to 25 heteroatoms of C, N, O or S.

[0078] And the amount of the above phosphate is reacted with 0.1 to 50%, the pH is adjusted to 2 to 6, and the surface is modified to form an organic protective film and can be stably dispersed in an organic solvent.

[0079] Additionally, the phosphate may include at least one of the molecular structures shown in the following chemical formula 4, or 2-ethylhexyl phosphate (EHP).

[0080] [Chemical Formula 4]

[0081]

[0082]

[0083] In addition, as mentioned above, the organic MXene manufactured by modifying the surface of the MXene with various organic ligands can be coated on a metal foil, and the organic MXene manufactured by applying an organic etching method can be coated on a metal foil.

[0084] An organic etching method according to an embodiment of the present invention comprises preparing MAX and then organically etching A of the MAX using an organic etching reagent and an organic solvent (wherein M is a transition metal, A is a group 14 element, and X is carbon or nitrogen).

[0085] The organic etching reagent according to an embodiment of the present invention may be an organic base-hydrogen fluoride addition product.

[0086] And the organic base is an organic base compound, and the organic base compound may be an organic base, an organic base derivative, or an organic base and a polymer bonding compound or mixture that dissolves better in an organic solvent than in water and allows hydrogen fluoride to remain in the organic solvent by stirring or heating.

[0087] Additionally, the organic base-hydrogen fluoride adduct may be at least one of a pyridine-hydrogen fluoride adduct (Olah's Reagent), an N,N-dimethylpropylene urea (DMPU)-hydrogen fluoride adduct (DMPU-HF adduct), and an alc triethylamine (TEA)-hydrogen fluoride adduct (TEA-HF adduct).

[0088] Additionally, the organic base-hydrogen fluoride addition product may be at least one of those represented by the following chemical formula 5.

[0089] [Chemical Formula 5]

[0090]

[0091] And the organic base compound may be at least one of those shown in the chemical formula 6 below.

[0092] [Chemical Formula 6]

[0093]

[0094]

[0095] In the above chemical formula 1, x and y are mutually dependent, the sum is 100% and each has a value of 10% to 90%, the range of n is 1 to 100,000, and R, R', R'' are each independently an aliphatic hydrocarbon and perfluoroalkyl, or an aromatic hydrocarbon and a heterocyclic compound having a length of C1 to C25.

[0096] Below, experimental examples of the present invention and experimental result data will be described.

[0097] MXene synthesis

[0098] 45 mL of HCl, 15 mL of distilled water, and 4.8 g of LiF were added to a Teflon round-bottom flask, and the mixture was heated and stirred at 50°C for 30 minutes.

[0099] Then, 3 g of MAX (Ti3AlC2) was added, heated and stirred at 50°C for 24 hours, and the solution was transferred to a conical tube and centrifuged repeatedly until the pH became 7. After that, centrifugation was performed at 12,000 rpm for 1 hour, and the MAXene portion excluding the precipitated aluminum portion was extracted (MILD synthesis method).

[0100]

[0101] Synthesis of surface-modified MXene-2ethylhexyl phosphate (EHP) (various other ligands can also be used) - Example 1

[0102] Phosphate-based surface-modified MXene was prepared by adding 12.5 mg of EHP to an aqueous MXene solution and stirring for 5 hours. Hexanol was added to the mixed solution, stirring was repeated, and the resulting layer was separated into upper and lower layers by decantation.

[0103] The organic phase solution was then washed three times with hexanol using centrifugation at 8,000 rpm to remove residual phosphate ligands. The surface-modified MXene was finally dispersed in ethanol using centrifugation.

[0104]

[0105] Manufacturing of MXene-EHP / LFP composite cathode materials and electrode fabrication

[0106] Mixed with unmodified Maxine LFP in ethanol, stirred for 1 hour and 60 oIt was prepared by drying in a C oven for 3 to 4 hours (MXene / LFP).

[0107] The prepared surface-modified MXene was mixed in LFP and ethanol, stirred for 1 hour and 60 o It was prepared by drying in a C oven for 3 to 4 hours (MXene-EHP / LFP).

[0108] Example 2 was prepared by mixing MXene / LFP and Super-P, CMC binder in a ratio of 75:15:10 to prepare a slurry. After preparing the slurry, it was coated on aluminum foil with a thickness of 100 μm and then 100 o The electrodes were prepared by drying in a C vacuum oven. The electrode preparation process was performed in a dry room with a negative pressure of 60 degrees and a humidity of <1 ppm.

[0109] Example 3 was prepared by mixing MXene-EHP / LFP and Super-P, CMC binder in a ratio of 75:15:10 to prepare a slurry. After preparing the slurry, it was coated on aluminum foil with a thickness of 100 μm and then 100 o The electrodes were prepared by drying in a C vacuum oven. The electrode preparation process was performed in a dry room with a negative pressure of 60 degrees and a humidity of <1 ppm.

[0110] For the comparative example, a slurry was prepared by mixing LFP, Super-P, and CMC binder in a ratio of 75:15:10. After preparing the slurry, it was coated on aluminum foil with a thickness of 100 μm and then 100 o The electrodes were prepared by drying in a C vacuum oven. The electrode preparation process was performed in a dry room with a negative pressure of 60 degrees and a humidity of <1 ppm.

[0111]

[0112] Fig. 2 illustrates an electron micrograph of positive electrode active material (LFP, LiFePO4) particles. Fig. 3 illustrates an electron micrograph of positive electrode active material (MXene / LFP) particles to which MXene is bound according to an embodiment of the present invention. As shown in the electron micrograph of Fig. 3 and the Ti K series, it can be seen that MXene is bound to the surface of the positive electrode active material (LFP) according to Example 2.

[0113] Figure 4 shows an electron micrograph of a positive electrode active material (MXene-EHP / LFP) particle having a phosphate-modified MXene surface bound thereto according to an embodiment of the present invention. As shown in the electron micrograph of Figure 4 and the Ti K series, it can be seen that the organic MXene was bound to the surface of the positive electrode active material (LFP) according to Example 3.

[0114] Fig. 5 shows surface electron micrographs and cross-sections of LFP, MXene / LFP, and MXene-EHP / LFP, respectively. As shown in Fig. 5, it can be seen that the MXene of MXene-EHP / LFP (Example 3) is more uniformly and stably bound to the cathode active material than that of MXene / LFP (Example 2).

[0115]

[0116] Fig. 6 illustrates an exploded perspective view of a battery manufactured according to an experimental example of the present invention. As shown in Fig. 6, batteries using each of Examples 2 and 3 and Comparative Example as anodes were manufactured and experiments were conducted.

[0117] FIG. 7 and FIG. 8 illustrate graphs of electrochemical impedance (EIS) results for LFP (comparative example), MXene / LFP (example 2), and MXene-EHP / LFP (example 3) according to experimental examples of the present invention, respectively.

[0118] As shown in FIGS. 7 and 8, the R value before the cycle is 1.5 times lower than that of MXene-EHP / LFP (Example 3) without surface treatment (Example 2) and about 3 times lower than that of LFP (Comparative Example) (86.26 / 131.54 / 215.83).

[0119] In addition, it can be seen that the R value of MXene-EHP / LFP (Example 3) after the cycle is 1.8 times lower than that of MXene without surface treatment (Example 2) and 7 times lower than that of LFP (Comparative Example) (26.87 / 48.83 / 181.54).

[0120]

[0121] Fig. 9 illustrates oxidation potential graphs of LFP (comparative example), MXene / LFP (example 2), and MXene-EHP / LFP (example 3) according to experimental examples of the present invention. As shown in Fig. 9, the oxidation potential of LFP (comparative example) appears at 3.69-3.63 V, and it can be seen that a reversible redox reaction is confirmed whether MXene is mixed (example 2) or MXene-EHP is mixed (example 3).

[0122]

[0123] Fig. 10 illustrates discharge capacity graphs of LFP (comparative example), MXene / LFP (example 2), and MXene-EHP / LFP (example 3) according to experimental examples of the present invention. As shown in the figure, it can be seen that MXene-EHP / LFP (example 3) has a higher discharge capacity than the comparative example and example 2 (1.27 times higher than the comparative example).

[0124]

[0125] Figure 11 illustrates the specific capacity at C-rate of LFP (comparative example), MXene / LFP (example 2), and MXene-EHP / LFP (example 3) according to the experimental examples of the present invention. As illustrated in Figure 11, the capacity retention rate when going from 5C to 0.2C is

[0126] LFP (comparative example): 85% (123 mAh / g)

[0127] MXene / LFP (Example 2): 89% (134 mAh / g)

[0128] MXene-EHP / LFP (Example 3): 92% (147 mAh / g)

[0129] It can be seen that MXene-EHP / LFP (Example 3) shows a stable capacity retention rate at a higher C-rate than the comparative example and Example 2.

[0130]

[0131] FIG. 12 illustrates a graph of Specific Capacity for 500 cycles at 1C rate of LFP (comparative example), MXene / LFP (example 2), and MXene-EHP / LFP (example 3) according to an experimental example of the present invention.

[0132] As shown in Fig. 12, Examples 2 and 3 show high capacity retention even after 500 cycles at 1C (Example 3 MXene-EHP / LFP: 92%). It can be seen that Example 3 (MXene-EHP / LFP) has the highest capacity compared to Comparative Example 2.

[0133]

[0134] FIG. 13 illustrates a graph of Specific Capacity for 1000 cycles at a 4C rate of LFP (comparative example), MXene / LFP (example 2), and MXene-EHP / LFP (example 3) according to an experimental example of the present invention.

[0135] As shown in Fig. 13, it can be seen that Mxene-EHP / LFP (Example 3) maintains its capacity compared to LFP (Comparative Example) which loses capacity at high C (4C) and long cycles (1000 cyc).

[0136]

[0137] FIG. 14 shows discharge capacity graphs of 1, 2, 100, 200, 300, 400, and 500 cycles at 1C rate of LFP (comparative example), MXene / LFP (example 2), and MXene-EHP / LFP (example 3) according to experimental examples of the present invention.

[0138] As shown in Fig. 14, MXene-EHP / LFP (Example 3) has a higher capacity after 500 cycles than the comparative example and Example 2, and when MXene is added to LFP (Examples 2 and 3), the capacity decrease is lower than that of LFP without MXene (Comparative Example).

[0139]

[0140] In addition, the devices and methods described above are not limited to the configurations and methods of the embodiments described above, and the embodiments may be configured by selectively combining all or part of each embodiment so that various modifications can be made.

Claims

1. As an active material for capacitors or secondary batteries, active material; and An active material having a two-dimensional MXene bonded to the surface of the above active material particle; 2. In paragraph 1, The above active material is a cathode active material, and the two-dimensional maxene is an active material combined with maxene, which is coated on the surface of the cathode active material.

3. In paragraph 2, The above Maxine is coated in a thin film form on the surface of the metal foil, The above two-dimensional MXene is M n+1 X n Crystal cells having an empirical formula of at least one layer forming a two-dimensional array, wherein X is located within an octahedral array composed of M, An active material in which M is a metal selected from the group consisting of a group IIIB metal, a group IVB metal, a group VB metal, and a group VIB metal, and X is C, N, or a combination thereof, and n=1,2,3, or 4.

4. In paragraph 3, The above two-dimensional MXene is M'2M" n X n+1 Crystal cells having an empirical formula of at least one layer forming a two-dimensional array, wherein X is located within an octahedral array composed of M, The above M' and M" are different metals selected from the group consisting of Group IIIB metals, Group IVB metals, Group VB metals, and Group VIB metals, An active material in which X is C, N or a combination thereof, and n=1 or 2, and a MXene is bonded.

5. In paragraph 1, The above two-dimensional MXene is an organic MXene whose surface is hydrophobically modified by an organic ligand, and is an active material to which MXene is bound.

6. In paragraph 5, The above organic MXene is modified on the outer surface of the two-dimensional MXene with one selected from the group consisting of a compound containing a hydroxyl group, an ionic compound, an azide-based surface-modifying compound, a phosphate having a saturated or unsaturated hydrocarbon, and a combination thereof. The compound containing the above hydroxyl group is at least one of a catechol derivative, a diol compound, a boronic acid compound, a carboxylic acid compound, a sulfonic acid compound, and a sulfinic acid compound. The above ionic compound is a cation selected from the group consisting of imidazolium compounds, pyridinium compounds, ammonium compounds, phosphinium compounds, and combinations thereof; and F - , Cl - , Br - , I - , BF 4- , PF 6- , (CF3SO2)2N - , CF3SO3 - , C2N 3- , CH3SO 3- , CF3BF 3- , C2F5BF 3- , NO 3- , CF3CO 2- , C3H5O 3- An active material comprising a MAXEN compound and an anion selected from a combination thereof.

7. In paragraph 6, The phosphate having the above saturated or unsaturated hydrocarbon is an active material to which MXene is bonded, represented by the following chemical formula 3: [Chemical Formula 3] The above A1, A2 or A3 is a hydrogen atom (-H), a C1-25 saturated or unsaturated hydrocarbon, It is selected from at least one of an amide group (-CONHR), a thioester group (-COSR), and an ester group (-RO-R'-).

8. In paragraph 7, The above A1, A2 or A3 are each independently C 1-25 Alkyl, C 2-25 Alkenyl, C 2-25 alkynyl, C 6-25 A saturated or unsaturated ring or chain hydrocarbon selected from aryl, or containing or not containing 1 to 25 heteroatoms of C, N, O or S, or unsubstituted or substituted with a functional group of hydroxy or carboxyl group, An active material combined with MXene, which is reacted with 0.1 to 50% of the above-mentioned phosphate, adjusted to pH 2 to 6, and surface-modified to form an organic protective film and is stably dispersed in an organic solvent.

9. In paragraph 8, The above phosphate is an active material bound to MXene, which comprises at least one of the molecular structures shown in the following chemical formula 2 and 2ethylhexyl phosphate (EHP): [Chemical Formula 4] 10. In paragraph 1, The above two-dimensional maxine is an organic maxine, The above organic MAX is an active material in which 2 MAXs are combined, and A of the above MAX is organically etched using an organic etching reagent and an organic solvent.

11. In paragraph 2, The above cathode active material is an active material combined with MXene, which is at least one of NCM type and iron phosphate type.

12. A secondary battery comprising a cathode active material combined with a maxine according to any one of claims 2 to 11.

13. A supercapacitor comprising an active material according to any one of claims 1 to 10.

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