Preparation method of MXene / waterborne polyurethane / cobalt hydroxide composite film and application of MXene / waterborne polyurethane / cobalt hydroxide composite film in flexible stretchable supercapacitor

Abstract

The invention belongs to the technical field of functional composite materials, and relates to a preparation method of an MXene / waterborne polyurethane / cobalt hydroxide composite film, which comprises the following steps: firstly, mixing an MXene colloidal solution with waterborne polyurethane WPU, and carrying out vacuum filtration to obtain an MXene / WPU composite film; and carrying out constant-voltage electrodeposition in a cobalt salt solution by taking the composite membrane as a working electrode, so that the cobalt hydroxide nanosheets are uniformly loaded on the surface of the membrane, and finally obtaining the ternary composite membrane. The stretchable template is constructed through the synergistic effect of MXene and WPU, and the pseudocapacitance characteristic of cobalt hydroxide is combined, so that the composite film has excellent mechanical flexibility and high electrochemical performance. The composite film is also used as a positive electrode to be assembled into a flexible stretchable supercapacitor, and the flexible stretchable supercapacitor shows high energy density and good cycling stability. The preparation method is simple in process and low in cost, and the prepared composite film has excellent mechanical flexibility and electrochemical energy storage performance and has a wide application prospect in the field of flexible electronics.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional composite materials, and relates to a composite electrode material, in particular to a preparation method of a MXene / water-based polyurethane / cobalt hydroxide composite film and application of the MXene / water-based polyurethane / cobalt hydroxide composite film to a flexible stretchable supercapacitor. BACKGROUND

[0002] In recent years, flexible electronics have been rapidly developed in many fields such as wearable multifunctional sensors, electronic skin, human-machine interface, soft robot, flexible display, etc. With the progress of technology, people are increasingly interested in developing energy storage devices that are mechanically compatible with these emerging devices. Flexible electronic products require their power supply devices to output stable and long-lasting electrical energy under various deformation conditions such as bending, twisting and stretching, so as to ensure the sustainable operation of the entire flexible electronic system. However, most traditional power supply devices are planar and rigid structures. Once subjected to external forces (such as bending, stretching), the energy storage characteristics will be greatly reduced or even lost, which cannot meet the needs of flexible electronic systems. Under this background, it is particularly important to develop efficient flexible energy storage devices.

[0003] Among many energy storage devices, stretchable supercapacitors, as a new type of energy storage device that has been rapidly developed in recent years, have the advantages of fast charge-discharge speed, good cycle stability, simple structure and easy manufacturing, etc. Due to the above performance advantages and structural advantages, flexible stretchable supercapacitors stand out among many energy storage devices and are considered as one of the ideal power sources for flexible electronic devices.

[0004] MXene has a metal-like conductivity (more than 10000 S cm -1 ), high specific capacitance (up to 1500 F cm -3 ), good solution processability and good mechanical flexibility, and is considered as a promising flexible supercapacitor electrode material. For example, after the dispersion of few-layer MXene nanosheets in solution, flexible thin films can be easily assembled by vacuum filtration as supercapacitor electrodes. In addition, the inherent layered structure of the parallel stacked MXene nanosheets can form a flexible MXene film that can withstand bending. However, due to the influence of van der Waals force, the MXene film layers are prone to stacking, which weakens the electrochemical performance. Moreover, these thin films are prone to breakage during stretching deformation and cannot be directly used in stretchable devices.

[0005] At present, the structural design of most flexible stretchable supercapacitors is to make the geometric structure of non-stretchable (but flexible) materials into undulating, serpentine, spiral and braided, or to load electrochemically active substances on the surface of stretchable materials. However, for such materials based on structural engineering, the interface is difficult to be firm, the assembly process is complex, which seriously restricts the improvement of electrochemical performance and large-scale application. In this regard, it has important research value and application prospect to develop high-performance MXene-based intrinsic stretchable electrodes and directly apply them to flexible stretchable supercapacitors. SUMMARY

[0006] In view of the problem that the MXene film in the prior art is difficult to have high stretchability and excellent electrochemical performance, the purpose of the present application is to provide a preparation method of a MXene / water-based polyurethane / cobalt hydroxide composite film.

[0007] TECHNICAL SOLUTION

[0008] The preparation method of the MXene / water-based polyurethane / cobalt hydroxide (MXene / WPU / Co(OH)2) composite film comprises the following steps:

[0009] A. Deionized water is used as a solvent, and is uniformly dispersed and stirred by ultrasonic to prepare a 4 mg mL -1 MXene colloidal solution, water-based polyurethane (WPU) is added, and after uniform stirring and mixing, the MXene / WPU composite film is obtained by vacuum filtration and room temperature drying, wherein the volume mass ratio of the MXene colloidal solution to the water-based polyurethane is 10 mL : 0.8-1 g, and preferably 10 mL : 0.8 g;

[0010] B. The obtained MXene / WPU composite film (1 cm x 1 cm) is used as a working electrode, Ag / AgCl is used as a reference electrode, and a platinum sheet is used as a counter electrode, and constant voltage electrodeposition is carried out in an electrodeposition solution containing Co 2+ salt, the voltage is-1 V, the deposition time is 15-30 min, and preferably 20 min; after the deposition is completed, the product is washed alternately with anhydrous ethanol and deionized water, and the MXene / WPU / Co(OH)2 composite film is obtained after room temperature drying.

[0011] In the preferred disclosure of the present application, in step A, the preparation method of the MXene comprises: 1 g of Ti3AlC2 is slowly added to a solution prepared by mixing 10 mL of HCl, 10 mL of HF and 5 mL of deionized water, and reacted at 35 DEG C for 12 h; after etching, the dispersion liquid is centrifuged and washed until the supernatant pH is greater than or equal to 6; the precipitate is taken, 10 mL of lithium chloride solution is added and stirred for 12 h, and then centrifuged and washed to obtain clay-like MXene, which is freeze-dried at-56 DEG C.

[0012] In a preferred embodiment of the present invention, in step A, the water content of the WPU is 40%, and the lithium chloride solution is prepared by dissolving 1 g of lithium chloride powder in 20 mL of deionized water.

[0013] In a preferred embodiment of the present invention, in step B, the Co 2+ The salt content is 10–20 mmol Co(NO3)2, preferably 15 mmol.

[0014] In a preferred embodiment of the present invention, in step B, the filter membrane used for vacuum filtration is made of nylon with a pore size of 0.22 μm.

[0015] The MXene / waterborne polyurethane / cobalt hydroxide composite film prepared by the method described in this invention has cobalt hydroxide uniformly loaded on the surface of the MXene / WPU film.

[0016] Another objective of this invention is to apply the prepared MXene / waterborne polyurethane / cobalt hydroxide composite film material to the electrode of a flexible stretchable supercapacitor.

[0017] Application Experiment Steps:

[0018] Using a single MXene / WPU / Co(OH)2 composite membrane (1×1 cm) 2 ) as the positive electrode, a single MXene / WPU composite membrane (1×1 cm) 2 Using PVA / KOH gel as the electrolyte and a negative electrode as the negative electrode, a fully solid-state asymmetric flexible stretchable supercapacitor is assembled. Before assembly, the electrode sheets are immersed in PVA / KOH gel for 30 min, cured at room temperature for 4 h, then stacked, and a layer of gel electrolyte is coated on the surface. The PVA / KOH gel is formed by dissolving 2.24 g KOH in 40 mL of deionized water, adding 2 g PVA powder, and stirring at 90 ℃ until a transparent gel is formed.

[0019] The MXene / waterborne polyurethane / cobalt hydroxide composite membrane material prepared by this invention has the following advantages:

[0020] (1) The synergistic effect of MXene and WPU as a stretchable template endows the composite membrane with high stretchability and mechanical stability;

[0021] (2) Co(OH)2 acts as a pseudocapacitive material, providing high specific capacitance and improving overall electrochemical performance;

[0022] (3) The assembled supercapacitor at 1 mA cm⁻¹ -2 At current density, the specific capacity reaches as high as 1650.8 mWh / m³. -2 , at 2 mA cm -2The capacitance retention rate is 88.2% after 5000 cycles at a current density, demonstrating superior electrochemical performance.

[0023] This invention uses flexible MXene / WPU as a template and loads cobalt hydroxide onto the surface of MXene / WPU via electrodeposition to obtain an MXene / WPU / Co(OH)2 composite film material. The preparation process is simple, easy to operate, and the reaction conditions are mild. The resulting film samples exhibit excellent electrochemical and mechanical properties.

[0024] Beneficial effects

[0025] This invention utilizes a self-assembly combined with electrodeposition method to prepare an MXene / WPU / Co(OH)2 composite membrane material by adjusting factors such as the ratio of MXene and aqueous polyurethane, the concentration of the deposition solution, and the electrodeposition time. The flexible stretchable supercapacitor based on this composite membrane material exhibits excellent electrochemical energy storage performance as well as stretchable and bendable mechanical properties. The process of this invention is simple, environmentally friendly, safe, and low-cost. This material possesses excellent mechanical flexibility and electrochemical energy storage performance, and is expected to be applied in flexible stretchable supercapacitors. Attached Figure Description

[0026] Figure 1 X-ray diffraction (XRD) pattern of the MXene / WPU / Co(OH)2 composite membrane material prepared in Example 1;

[0027] Figure 2 Scanning electron microscope (SEM) image of the MXene / WPU / Co(OH)2 composite membrane material prepared in Example 1;

[0028] Figure 3 The asymmetric supercapacitor device assembled from the product prepared in Example 1 operates at 2 mA cm⁻¹. -2 Cyclic performance at current density;

[0029] Figure 4 The asymmetric supercapacitor device assembled from the product prepared in Example 1 achieved a voltage of 30 mV / s. -1 Capacitance retention rate under the condition of stretching with an elongation of 50-150% at a sweeping speed. Detailed Implementation

[0030] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0031] Unless otherwise specified, the terminology used herein (including technical terms) shall be construed as having the same meaning commonly understood by one of ordinary skill in the art to which this invention pertains. It will also be understood that the terminology used herein shall be construed as having the same meaning as it has in the context of this specification and related art, and shall not be interpreted in an idealized or excessive manner, unless specifically defined herein.

[0032] Example 1

[0033] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0034] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it, and the mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was finally freeze-dried at -56 °C.

[0035] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0036] (3) Add 0.8 g of aqueous polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, then vacuum filter the mixture and dry it at room temperature to obtain the MXene / WPU composite membrane:

[0037] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 15 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 20 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0038] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 1650.8 mWh. -2 , at 2mA cm -2 The capacitance retention rate is 88.2% after 5000 cycles at a current density.

[0039] Figure 1 The figure shows the X-ray diffraction (XRD) pattern of the MXene / WPU / Co(OH)2 composite membrane prepared in this embodiment. As can be seen from the figure, the position of the characteristic peak of the product is consistent with the characteristic peak of MXene, WPU and Co(OH)2, indicating that the MXene / WPU / Co(OH)2 composite membrane material was successfully prepared.

[0040] Figure 2 This is a scanning electron microscope (SEM) image of the MXene / WPU / Co(OH)2 composite film prepared in this embodiment, which shows that cobalt hydroxide nanosheets are uniformly loaded on the surface of the composite film.

[0041] Figure 3 The asymmetric supercapacitor device assembled from the product prepared in this embodiment operates at 2 mA cm⁻¹. -2 Cyclic performance at current density.

[0042] Figure 4 The asymmetric supercapacitor device assembled from the product prepared in this embodiment operates at 30 mV s. -1 Capacitance retention rate under the condition of stretching with an elongation of 50-150% at a sweeping speed.

[0043] Example 2

[0044] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0045] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it. The mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was then freeze-dried at -56 °C.

[0046] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0047] (3) Add 0.9 g of waterborne polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, then vacuum filter the mixture and dry it at room temperature to obtain an MXene / WPU composite membrane;

[0048] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 15 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 20 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0049] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 1245.2 mWh. -2 .

[0050] Example 3

[0051] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0052] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it, and the mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was then freeze-dried at -56 °C.

[0053] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0054] (3) Add 1 g of waterborne polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, vacuum filter the mixed liquid and dry it at room temperature to obtain the MXene / WPU composite membrane;

[0055] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 15 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 20 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0056] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 936.7 mWh. -2 .

[0057] Example 4

[0058] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0059] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it, and the mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was finally freeze-dried at -56 °C.

[0060] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0061] (3) Add 0.9 g of waterborne polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, then vacuum filter the mixture and dry it at room temperature to obtain an MXene / WPU composite membrane;

[0062] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 10 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 20 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0063] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 1082.1 mWh. -2 .

[0064] Example 5

[0065] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0066] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it, and the mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was finally freeze-dried at -56 °C.

[0067] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0068] (3) Add 0.9 g of waterborne polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, then vacuum filter the mixture and dry it at room temperature to obtain an MXene / WPU composite membrane;

[0069] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 20 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 20 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0070] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 1354.8 mWh. -2 .

[0071] Example 6

[0072] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0073] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it, and the mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was finally freeze-dried at -56 °C.

[0074] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0075] (3) Add 0.9 g of waterborne polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, then vacuum filter the mixture and dry it at room temperature to obtain an MXene / WPU composite membrane;

[0076] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 15 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 15 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0077] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 1176.9 mWh. -2 .

[0078] Example 7

[0079] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0080] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it, and the mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was finally freeze-dried at -56 °C.

[0081] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0082] (3) Add 0.9 g of waterborne polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, then vacuum filter the mixture and dry it at room temperature to obtain an MXene / WPU composite membrane;

[0083] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 15 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 25 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0084] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 1493.1 mWh. -2 .

[0085] Example 8

[0086] A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane includes the following steps:

[0087] (1) 1 g Ti3AlC2 was slowly added to a mixed solution consisting of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacted at 35 °C for 12 hours. After etching, the resulting dispersion was centrifuged and washed with deionized water until the pH of the supernatant was ≥6. The precipitate after centrifugation was taken, and lithium chloride solution was added to it, and the mixture was stirred at room temperature for 12 h. The resulting suspension was centrifuged and washed several times to obtain clay-like MXene, which was then freeze-dried at -56 °C.

[0088] (2) Weigh 40 mg of MXene, add 10 mL of deionized water, stir and ultrasonically disperse evenly to obtain an MXene colloidal solution;

[0089] (3) Add 0.9 g of waterborne polyurethane (WPU) to the MXene colloidal solution, stir for 30 min, then vacuum filter the mixture and dry it at room temperature to obtain an MXene / WPU composite membrane;

[0090] (4) Using the obtained MXene / WPU composite membrane (1 cm × 1 cm) as the working electrode, Ag / AgCl as the reference electrode, a platinum sheet as the counter electrode, and 40 mL of 15 mmol Co(NO3)2 solution as the electrodeposition solution, constant voltage deposition was performed at -1 V for 30 min. The product was washed alternately with anhydrous ethanol and deionized water and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

[0091] A flexible, stretchable supercapacitor assembled using the prepared MXene / aqueous polyurethane / cobalt hydroxide composite film as the positive electrode and MXene / aqueous polyurethane as the negative electrode operates at a current density of 1 mA cm⁻¹. -2 Below, the capacity is 1349.2 mWh. -2 .

[0092] The embodiments described above are merely specific implementations of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing an MXene / waterborne polyurethane / cobalt hydroxide composite membrane, characterized in that, Includes the following steps: A. Add MXene to deionized water and ultrasonically disperse and stir until uniform to prepare MXene colloidal solution. Add waterborne polyurethane (WPU) and stir until uniform. After vacuum filtration and room temperature drying, obtain MXene / WPU composite membrane. B. Using the obtained MXene / WPU composite film as the working electrode, Ag / AgCl as the reference electrode, and a platinum sheet as the counter electrode, in a Co-containing environment... 2+ Constant voltage electrodeposition was performed in the salt electrodeposition solution. After deposition, the product was washed alternately with anhydrous ethanol and deionized water, and dried at room temperature to obtain the MXene / WPU / Co(OH)2 composite membrane.

2. The method for preparing the MXene / aqueous polyurethane / cobalt hydroxide composite membrane according to claim 1, characterized in that, In step A, the preparation of MXene includes: slowly adding 1 g Ti3AlC2 to a solution composed of 10 mL HCl, 10 mL HF and 5 mL deionized water, and reacting at 35 °C for 12 h; after etching, centrifuging and washing the dispersion until the pH of the supernatant is ≥6; taking the precipitate, adding lithium chloride solution and stirring for 12 h, centrifuging and washing to obtain clay-like MXene, and freeze-drying at -56 °C to obtain the final product.

3. The method for preparing the MXene / aqueous polyurethane / cobalt hydroxide composite membrane according to claim 1, characterized in that: In step A, the water content of the WPU is 40%, and the lithium chloride solution is prepared by dissolving 1 g of lithium chloride powder in 20 mL of deionized water.

4. The method for preparing the MXene / aqueous polyurethane / cobalt hydroxide composite membrane according to claim 1, characterized in that: In step A, the concentration of the MXene colloidal solution is 4 mg / mL. -1 The volume-to-mass ratio of MXene colloidal solution to aqueous polyurethane is 10 mL : 0.8–1 g.

5. The method for preparing the MXene / aqueous polyurethane / cobalt hydroxide composite membrane according to claim 4, characterized in that: In step A, the volume-to-mass ratio of the MXene colloidal solution to the aqueous polyurethane is 10 mL : 0.8 g.

6. The method for preparing the MXene / aqueous polyurethane / cobalt hydroxide composite membrane according to claim 1, characterized in that: In step B, the electrodeposition solution is Co(NO3)2 with a concentration of 10-20 mmol, preferably 15 mmol; the constant voltage electrodeposition voltage is -1 V, and the deposition time is 15-30 min, preferably 20 min; the filter membrane used for vacuum filtration is made of nylon with a pore size of 0.22 μm.

7. The MXene / waterborne polyurethane / cobalt hydroxide composite membrane prepared by any one of the methods described in claims 1-6.

8. A flexible, stretchable supercapacitor electrode, characterized in that: It is made of the MXene / waterborne polyurethane / cobalt hydroxide composite membrane as described in claim 7.

9. The flexible stretchable supercapacitor electrode according to claim 8, characterized in that: The capacitor electrode has an all-solid-state asymmetric structure, including a positive electrode, a negative electrode, and a gel electrolyte. The positive electrode is the MXene / aqueous polyurethane / cobalt hydroxide composite membrane according to claim 7, and the negative electrode is the MXene / aqueous polyurethane composite membrane.

10. The flexible stretchable supercapacitor electrode according to claim 9, characterized in that: The gel electrolyte is a PVA / KOH gel.

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