A monolithic membrane-based flexible supercapacitor

Abstract

The present invention discloses a monolithic membrane-based flexible supercapacitor and its preparation method and application. The supercapacitor uses a nylon filter membrane as a diaphragm and an electrolyte storage layer, a sodium carboxymethyl cellulose / phytic acid / polyaniline membrane formed by drip coating as the positive and negative electrodes, and triammonium dihydrogen disulfate as the electrolyte. The present invention designs a sodium carboxymethyl cellulose / phytic acid / polyaniline ink having both electrode active ingredients and electrolyte active ingredients, and prepares a monolithic membrane-based flexible supercapacitor by a double-sided drip coating method in which the ink is dripped onto both sides of a nylon filter membrane. The monolithic membrane-based flexible supercapacitor prepared by the present invention has the advantages of being ultra-light, ultra-thin, having high specific capacitance, being able to withstand mechanical bending, and being able to be arbitrarily patterned. It has broad prospects in the field of flexible portable electronic devices as a flexible energy storage device.

Description

Technical Field

[0001] The present invention belongs to the field of new energy, and specifically relates to a flexible supercapacitor and a preparation method and application thereof. Background Art

[0002] Over the past two decades, the development of the Internet of Things has brought tremendous convenience to our daily lives. This has led to the development of various flexible portable electronic products, such as smart watches, home medical sensors, blood pressure monitors, activity monitors, and flexible displays. Flexible energy storage devices, such as flexible metal ion batteries and flexible supercapacitors, serve as core modules of flexible portable electronic devices. They directly determine the battery life, weight, and volume of these devices, and are therefore of great research significance. Flexible supercapacitors, among them, offer advantages such as high energy density, high power density, high current charge and discharge capability, safe and non-toxic electrolytes, no risk of overcharging, and a long charge and discharge cycle life, holding them as promising candidates for flexible portable electronic devices.

[0003] Flexible supercapacitors can be divided into stacked and planar types according to their configuration, among which the stacked type has the advantage of higher specific capacitance and thus longer battery life. However, the current stacked flexible supercapacitors are almost all two-piece structures, that is, the positive and negative electrodes are first prepared, the electrolyte is coated on them, and then the positive and negative electrodes are stacked face to face. However, in order to ensure mechanical strength, the positive and negative electrodes usually contain a flexible substrate that serves as a mechanical support, but the flexible substrate has no electrochemical activity, which increases the weight and volume of the device in vain. Therefore, the current flexible supercapacitors still have the disadvantage of being thick and heavy, which greatly limits their application in flexible portable electronic devices. Therefore, it is of great significance to develop flexible supercapacitors that have excellent energy storage performance, can withstand mechanical bending, and are both ultra-light and ultra-thin. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a monolithic membrane-based flexible supercapacitor for a flexible energy storage device and a preparation method thereof, so as to solve the disadvantage of the thickness of the flexible supercapacitor in the prior art.

[0005] In order to achieve the above object of the invention, the technical solution adopted by the present invention is as follows.

[0006] The present invention provides a monolithic membrane-based flexible supercapacitor comprising a nylon filter membrane and sodium carboxymethyl cellulose / phytic acid / polyaniline membranes formed on the upper and lower surfaces of the nylon filter membrane, wherein triammonium disulfate is adsorbed within the nylon filter membrane. The supercapacitor uses the nylon filter membrane as a separator and electrolyte storage layer, the sodium carboxymethyl cellulose / phytic acid / polyaniline membranes as the positive and negative electrodes, and the triammonium disulfate adsorbed within the nylon filter membrane as the electrolyte. The thickness of the sodium carboxymethyl cellulose / phytic acid / polyaniline membrane on one surface is approximately 5 to 55 μm, and the total thickness of the supercapacitor is approximately 110 to 210 μm.

[0007] Furthermore, the sodium carboxymethyl cellulose / phytic acid / polyaniline membrane is composed of nanoparticles with an average size of 200 to 300 nm, forming a stacked structure with interlocking nanoparticles. The small size of the nanoparticles increases the specific surface area, thereby improving, for example, capacitance. The interlocking structure ensures the integrity and crack-free nature of the electrode membrane, and also improves energy storage stability under repeated bending.

[0008] The present invention also provides a method for preparing the above-mentioned monolithic membrane-based flexible supercapacitor, comprising the following steps:

[0009] 1) Dissolve sodium carboxymethyl cellulose and phytic acid in water and stir to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution.

[0010] 2) adding aniline monomer to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirring to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution.

[0011] 3) Prepare an aqueous solution of ammonium persulfate as an initiator.

[0012] 4) The sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution are incubated at 0-5°C for 0.75-1 hour. The ammonium persulfate aqueous solution is added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution while stirring at high speed, and the mixture is allowed to stand in the dark at 0-5°C to allow the polymerization reaction to proceed. After the reaction is completed, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink is obtained. After the polymerization reaction is completed by standing, the resulting sodium carboxymethyl cellulose / phytic acid / polyaniline ink contains both the electrode active component polyaniline and the electrolyte active component triammonium disulfate; that is, the electrolyte active component triammonium disulfate is a product of the polymerization reaction itself and is not added externally.

[0013] 5) By the double-sided drop coating method, that is, the ink is drop-coated on both sides of the nylon filter membrane with a pipette. During the drying process, the electrolyte active ingredient triammonium disulfate in the ink will penetrate into the nylon filter membrane, and the electrode active ingredient polyaniline in the ink will form a sodium carboxymethyl cellulose / phytic acid / polyaniline film, i.e., an electrode film, on both sides of the nylon filter membrane under the joint action of sodium carboxymethyl cellulose / phytic acid, thereby obtaining the monolithic membrane-based flexible supercapacitor.

[0014] The present invention selects a nylon filter membrane as a diaphragm and an electrolyte storage layer, and combines the preparation process of the present invention to utilize the filtering effect of the nylon filter membrane. During the electrode membrane drop coating process, the nylon filter membrane can prevent the electrode active ingredient polyaniline nanoparticles from entering the interior of the filter membrane, but can allow the electrolyte active ingredient triammonium dihydrogen disulfate to smoothly penetrate into the interior of the filter membrane and be stored therein, thereby allowing the nylon filter membrane to play the dual role of a diaphragm and an electrolyte storage layer, and simultaneously ensures the necessary structure of sandwiching an electrolyte layer between the two electrode membranes on both sides of the filter membrane without short circuit.

[0015] Furthermore, in step 1), the mass percentage of sodium carboxymethyl cellulose in water is 1-2 wt.%, and the concentration of phytic acid in water is 0.00011±0.00001 mol mL -1 ; Step 2) The concentration of aniline monomer is 0.000483±0.00001molmL -1 In step 4), when the ammonium persulfate aqueous solution is added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution, the molar ratio of ammonium persulfate to aniline monomer is 1.1:1. In repeated experiments by the inventors, inks prepared with sodium carboxymethyl cellulose dosages below or above the 1-2 wt.% range failed to produce a structurally intact, crack-free electrode film on the nylon filter membrane.

[0016] Furthermore, in step 3), an aqueous ammonium persulfate solution is prepared by dissolving 1.212±0.003 g of ammonium persulfate in 5±0.5 mL of water.

[0017] Furthermore, in step 4), during the process of adding the ammonium persulfate aqueous solution under high-speed stirring, the reaction system temperature is 0-5° C., the high-speed stirring speed is 400-500 rpm, and the high-speed stirring time is 2 min ± 10 s to form a uniformly dispersed sodium carboxymethyl cellulose / phytic acid / polyaniline ink.

[0018] Furthermore, in step 4), the polymerization reaction time is 24 to 36 hours in a dark environment at 0 to 5°C.

[0019] Furthermore, the ink drop amount on one side in step 5) is 36-76 μL cm -2 The drying environment after applying the ink is at a temperature of 25-27°C and a humidity of 54-60%, and the drying time is 3±1h.

[0020] Furthermore, during the drop coating in step 5), a mask with various hollow patterns, referred to as a patterned mask, can be placed on the nylon filter membrane, and then the drop coating operation is performed. Thus, the appearance of the monolithic membrane-based flexible supercapacitor can be designed into any pattern.

[0021] Furthermore, the present invention also provides the application of the above-mentioned monolithic membrane-based flexible supercapacitor in a flexible energy storage device, with an area of ​​about 0.75±0.1cm 2 The monolithic film-based flexible supercapacitor has a thickness of about 200±10 μm, weighs about 0.21±0.01 g, and the device weight per unit area is as low as 0.28 g / cm 2 At 0.6 mA cm -2 The area specific capacitance at the current density is 757mF cm -2 , the volumetric capacitance is 37.8F cm -3 , at 1 mA cm -2 The capacitance retention rate after 2000 charge and discharge cycles at a current density of 0.8 mA cm- -2 The capacitance retention rate after repeated bending from 0 to 180 degrees for 2000 times under current density is 98%, and the appearance can be designed into any pattern.

[0022] The beneficial results of the present invention are:

[0023] (1) The present invention provides a new type of single-piece membrane-based flexible supercapacitor, which is effectively used in flexible energy storage devices, breaking the limitations of traditional two-piece configurations and solving the bottleneck problem of flexible supercapacitors being relatively thick and heavy and not portable enough.

[0024] (2) The present invention provides a sodium carboxymethyl cellulose / phytic acid / polyaniline ink containing both electrode active ingredients and electrolyte active ingredients, which avoids the need for an additional electrolyte coating step in traditional production processes and greatly simplifies the production steps.

[0025] (3) The present invention provides a double-sided drop coating method for preparing a monolithic membrane-based flexible supercapacitor. The method is easy to operate, can be prepared on a large scale, is fast and efficient, and has mild conditions, making it very suitable for industrialization.

[0026] (4) The double-sided drop coating method provided by the present invention, with the assistance of a patterned mask, can enable the monolithic membrane-based flexible supercapacitor to achieve arbitrary patterning of the appearance. It can be flexibly designed according to the actual use environment and can also be customized according to user preferences, showing broad market prospects.

[0027] (5) The monolithic membrane-based flexible supercapacitor prepared by the present invention exhibits excellent energy storage performance and has the advantages of being ultra-light and ultra-thin. It can still maintain its original energy storage performance to a great extent under repeated bending, and has great potential in the field of flexible portable electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of the monolithic membrane-based flexible supercapacitor produced by various embodiments of the present invention.

[0029] Figure 2 Thickness measurement diagram of the nylon filter membrane used in each example and the monolithic membrane-based flexible supercapacitor prepared in Example 4.

[0030] Figure 3 1 is the X-ray diffraction (XRD) pattern of the dry powder of the sodium carboxymethyl cellulose / phytic acid / polyaniline ink prepared in the process of Example 1.

[0031] Figure 4 This is a scanning electron microscope (SEM) image of the electrode membrane surface of the monolithic membrane-based flexible supercapacitor prepared in Example 1, magnified 5000 times.

[0032] Figure 5 This is a scanning electron microscope (SEM) image of the cross section of the monolithic membrane-based flexible supercapacitor prepared in Example 5, magnified 300 times.

[0033] Figure 6 This is a constant current charge and discharge (GCD) curve of the monolithic membrane-based flexible supercapacitor prepared in Example 1 at different current densities.

[0034] Figure 7 The area specific capacitance and volume specific capacitance of the monolithic membrane-based flexible supercapacitor prepared in Example 1 at different current densities.

[0035] Figure 8 The monolithic film-based flexible supercapacitor prepared in Example 1 has a capacitance of 1 mA cm -2 Capacitance retention after 2000 charge-discharge cycles at different current densities.

[0036] Figure 9 The 0.8 mA cm-2 of the monolithic film-based flexible supercapacitor prepared in Example 1 after repeated bending at 0-180° for 2000 times is shown in FIG. -2 GCD curve obtained from current density test.

[0037] Figure 10 This is a case picture of the monolithic film-based flexible supercapacitor prepared in Example 1, which can achieve arbitrary patterning of appearance with the assistance of a patterned mask. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to specific examples to enable those skilled in the art to better understand the present invention. The present invention is not limited to the following examples.

[0039] In each embodiment of the present invention, a nylon filter membrane with a thickness of about 100 μm is used as the diaphragm and electrolyte storage layer for making the monolithic membrane-based flexible supercapacitor of the present invention. The structural diagram of the monolithic membrane-based flexible supercapacitor made in each embodiment is shown in the attached figure. Figure 1 As shown, the left picture is a front schematic diagram, and the right picture is a cross-sectional schematic diagram. In the figure, 2 is a nylon filter membrane of the diaphragm and electrolyte storage layer, and the electrolyte active substance triammonium dihydrogen sulfate is adsorbed in the nylon filter membrane; in the figure, 1 is a single-sided sodium carboxymethyl cellulose / phytic acid / polyaniline film formed on the upper and lower surfaces of the diaphragm by drop coating, which serves as the positive and negative electrodes of the capacitor.

[0040] Example 1

[0041] 0.1 g of sodium carboxymethyl cellulose and 0.0011 mol of phytic acid were dissolved in 10 mL of water and stirred to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution; 0.00483 mol of aniline monomer was added to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirred to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution; 1.212 g of ammonium persulfate was dissolved in 5 mL of water to prepare an ammonium persulfate aqueous solution as an initiator; the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution were kept at 0° C. for 1 hour; the ammonium persulfate aqueous solution was added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution under high-speed stirring at 400 rpm for 2 minutes; and the mixture was allowed to stand in a dark environment at 0° C. for 24 hours to allow the polymerization reaction to continue. After the reaction, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink was obtained. The ink was applied to both sides of the nylon filter membrane using a simple double-sided drop coating method, i.e., a pipette was used to apply the ink. The single-sided drop coating amount of the ink was 60 ± 2 μL cm -2 The drying environment is a temperature of 27±2°C and a humidity of 54-60%, and the drying time is 3±1h to obtain the monolithic membrane-based flexible supercapacitor.

[0042] Example 2

[0043] 0.15 g of sodium carboxymethyl cellulose and 0.0011 mol of phytic acid were dissolved in 10 mL of water and stirred to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution; 0.00483 mol of aniline monomer was added to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirred to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution; 1.212 g of ammonium persulfate was dissolved in 5 mL of water to prepare an ammonium persulfate aqueous solution as an initiator; the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution were kept at 0° C. for 1 hour; the ammonium persulfate aqueous solution was added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution under high-speed stirring at 400 rpm for 2 minutes; and the mixture was allowed to stand in a dark environment at 0° C. for 24 hours to allow the polymerization reaction to continue. After the reaction, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink was obtained. The ink was applied to both sides of the nylon filter membrane using a simple double-sided drop coating method, i.e., a pipette was used to apply the ink. The single-sided drop coating amount of the ink was 60 ± 2 μL cm -2 The drying environment is a temperature of 27±2°C and a humidity of 54-60%, and the drying time is 3±1h to obtain the monolithic membrane-based flexible supercapacitor.

[0044] Example 3

[0045] 0.2 g of sodium carboxymethyl cellulose and 0.0011 mol of phytic acid were dissolved in 10 mL of water and stirred to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution; 0.00483 mol of aniline monomer was added to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirred to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution; 1.212 g of ammonium persulfate was dissolved in 5 mL of water to prepare an ammonium persulfate aqueous solution as an initiator; the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution were kept at 0° C. for 1 hour; the ammonium persulfate aqueous solution was added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution under high-speed stirring at 400 rpm for 2 minutes; and the mixture was allowed to stand in a dark environment at 0° C. for 24 hours to allow the polymerization reaction to continue. After the reaction, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink was obtained. The ink was applied to both sides of the nylon filter membrane using a simple double-sided drop coating method, i.e., a pipette was used to apply the ink. The single-sided drop coating amount of the ink was 60 ± 2 μL cm -2 The drying environment is a temperature of 27±2°C and a humidity of 54-60%, and the drying time is 3±1h to obtain the monolithic membrane-based flexible supercapacitor.

[0046] Example 4

[0047] 0.1 g of sodium carboxymethyl cellulose and 0.0011 mol of phytic acid were dissolved in 10 mL of water and stirred to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution; 0.00483 mol of aniline monomer was added to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirred to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution; 1.212 g of ammonium persulfate was dissolved in 5 mL of water to prepare an ammonium persulfate aqueous solution as an initiator; the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution were kept at 0° C. for 1 hour; the ammonium persulfate aqueous solution was added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution under high-speed stirring at 400 rpm for 2 minutes; and the mixture was allowed to stand in a dark environment at 0° C. for 24 hours to allow the polymerization reaction to continue. After the reaction, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink was obtained. The ink was applied to both sides of the nylon filter membrane using a simple double-sided drop coating method, i.e., a pipette was used to apply the ink. The single-sided drop coating amount of the ink was 30 ± 2 μL cm -2 The drying environment is a temperature of 27±2°C and a humidity of 54-60%, and the drying time is 3±1h to obtain the monolithic membrane-based flexible supercapacitor.

[0048] Example 5

[0049] 0.1 g of sodium carboxymethyl cellulose and 0.0011 mol of phytic acid were dissolved in 10 mL of water and stirred to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution; 0.00483 mol of aniline monomer was added to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirred to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution; 1.212 g of ammonium persulfate was dissolved in 5 mL of water to prepare an ammonium persulfate aqueous solution as an initiator; the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution were kept at 0° C. for 1 hour; the ammonium persulfate aqueous solution was added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution under high-speed stirring at 400 rpm for 2 minutes; and the mixture was allowed to stand in a dark environment at 0° C. for 24 hours to allow the polymerization reaction to continue. After the reaction, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink was obtained. The ink was applied to both sides of the nylon filter membrane using a simple double-sided drop coating method, i.e., a pipette was used to apply the ink to each side. The ink drop coating amount on each side was 40 ± 2 μL cm -2 The drying environment is a temperature of 27±2°C and a humidity of 54-60%, and the drying time is 3±1h to obtain the monolithic membrane-based flexible supercapacitor.

[0050] Example 6

[0051] 0.1 g of sodium carboxymethyl cellulose and 0.0011 mol of phytic acid were dissolved in 10 mL of water and stirred to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution; 0.00483 mol of aniline monomer was added to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirred to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution; 1.212 g of ammonium persulfate was dissolved in 5 mL of water to prepare an ammonium persulfate aqueous solution as an initiator; the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution were kept at 0° C. for 1 hour; the ammonium persulfate aqueous solution was added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution under high-speed stirring at 400 rpm for 2 minutes; and the mixture was allowed to stand in a dark environment at 0° C. for 24 hours to allow the polymerization reaction to continue. After the reaction, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink was obtained. The ink was applied to both sides of the nylon filter membrane using a simple double-sided drop coating method, i.e., a pipette was used to apply the ink to each side of the membrane. The ink application volume on each side was 50 ± 2 μL cm -2 The drying environment is a temperature of 27±2°C and a humidity of 54-60%, and the drying time is 3±1h to obtain the monolithic membrane-based flexible supercapacitor.

[0052] Performance testing:

[0053] 1) Thickness test: The thickness of the nylon filter membrane and the monolithic membrane-based flexible supercapacitor prepared in each embodiment was measured using an electronic micrometer. Figure 2 The thickness measurement diagram of the nylon filter membrane and Example 4 is shown on the left. The nylon filter membrane has a thickness of about 98 μm, and the supercapacitor prepared in Example 4 has a total thickness of 120 μm. The test results show that the total thickness of the monolithic membrane-based flexible supercapacitor prepared in each example is between 110 and 210 μm. After removing the thickness of the nylon filter membrane of about 100 μm, the total thickness of the sodium carboxymethyl cellulose / phytic acid / polyaniline membrane on both sides is about 10 to 110 μm, that is, the thickness of the sodium carboxymethyl cellulose / phytic acid / polyaniline membrane on one side is about 5 to 55 μm.

[0054] 2) Weight test: The monolithic membrane-based flexible supercapacitors prepared in each example were weighed on a precision electronic balance. For example, the monolithic membrane-based flexible supercapacitor prepared in Example 1 had an average mass of about 0.21 g and an area of ​​about 0.75 ± 0.1 cm 2 Therefore, the device weight per unit area is as low as 0.28g / cm 2 .

[0055] 2) XRD test: The sodium carboxymethyl cellulose / phytic acid / polyaniline ink prepared in the above embodiment was subjected to high-speed centrifugation, the bottom precipitate was collected, and the powder was dried to obtain an XRD test. It was confirmed that the sodium carboxymethyl cellulose / phytic acid / polyaniline ink finally prepared contained polyaniline as an electrode active ingredient and triammonium disulfate as an electrolyte active ingredient. Figure 3 The X-ray diffraction pattern of the dry powder of the sodium carboxymethyl cellulose / phytic acid / polyaniline ink prepared in Example 1 shows that the diffraction peak of the sample corresponds to the diffraction peak of triammonium dihydrogen disulfate and contains the main diffraction peak of polyaniline.

[0056] 3) SEM test: The monolithic film-based flexible supercapacitor prepared in the above embodiment was observed under a scanning electron microscope. Figure 4 This is a scanning electron microscope (SEM) image of the electrode membrane surface of the monolithic membrane-based flexible supercapacitor prepared in Example 1 at a magnification of 5000 times. In the image, it can be seen that the surface morphology of the monolithic membrane-based flexible supercapacitor electrode membrane prepared by the present invention is nanoparticles with an average size of 200 to 300 nm with a certain degree of adhesion. The small-sized nanoparticle morphology can increase the specific surface area, which is beneficial to improve, for example, capacitance. The adhesion structure can ensure the integrity and crack-free nature of the electrode membrane, and is also beneficial to improving the energy storage stability under repeated bending. Figure 5 This is a scanning electron microscope (SEM) image of a cross-section of the monolithic membrane-based flexible supercapacitor prepared in Example 5 at 300x magnification. The structure with a nylon filter membrane in the middle and electrode membranes on either side can be clearly observed. The filtration effect of the nylon filter membrane prevents the polyaniline nanoparticles (active electrode ingredient) from entering the filter membrane, but allows the electrolyte active ingredient (triammonium disulfate) to penetrate smoothly into the filter membrane, thereby acting as a separator and electrolyte storage layer. This ensures the necessary structure of the electrolyte layer sandwiched between the two electrode membranes without short circuits.

[0057] 4) Electrochemical performance test of electrodes: The monolithic membrane-based flexible supercapacitors prepared in Examples 1 to 6 were directly clamped with a copper clip for button-type batteries and connected to a Shanghai Chenhua CHI 760E electrochemical workstation for constant current charge and discharge (GCD) testing. The area specific capacitance (C) was calculated according to the following formula: Areal ,mF cm -2 ) and volumetric capacitance (C Vol ,F cm -3 ), where I, t, A, U, IR, and T represent current (A), discharge time (s), and electrode film area (cm 2 ), voltage range (V), potential drop (V), device thickness (cm), and calculated capacitance retention (CR), where C0, C nThey respectively represent the area specific capacitance or volume specific capacitance of the monolithic membrane-based flexible supercapacitor before and after specific treatment.

[0058]

[0059]

[0060] Attachment Figures 6-7 The GCD curves of the monolithic membrane-based flexible supercapacitor prepared in Example 1 at different current densities, as well as the calculated area specific capacitance and volume specific capacitance. -2 The area specific capacitance at the current density is 757mF cm -2 , the volumetric capacitance is 37.8F cm -3 .

[0061] Attachment Figure 8 The monolithic film-based flexible supercapacitor prepared in Example 1 has a capacitance of 1 mA cm -2 The capacitance retention rate graph after 2000 charge and discharge cycles at the current density is shown in Figure 2. The capacitance retention rate is obtained from this, at 1mA cm -2 The capacitance retention rate after 2000 charge and discharge cycles at the same current density is 112%, showing excellent charge and discharge cycle stability.

[0062] Attachment Figure 9 The 0.8 mA cm-2 of the monolithic film-based flexible supercapacitor prepared in Example 1 after repeated bending at 0-180° for 2000 times is shown in FIG. -2 The GCD curve obtained from the current density test and the capacitance retention rate calculated by the formula were 98%.

[0063] Attachment Figure 10 This is a case picture of the monolithic film-based flexible supercapacitor prepared in Example 1, which can achieve arbitrary patterning of appearance with the assistance of a patterned mask.

[0064] In summary, the area is approximately 0.75 ± 0.1 cm 2 The monolithic film-based flexible supercapacitor has a thickness of about 200±10 μm and a weight of about 0.21±0.01 g, and at 0.6 mA cm -2 The area specific capacitance at the current density is 757mF cm -2 , the volumetric capacitance is 37.8F cm -3 , at 1 mA cm -2 The capacitance retention rate after 2000 charge and discharge cycles at a current density of 0.8 mA cm- -2The capacitance retention rate is 98% after 2,000 repeated bends from 0 to 180 degrees at a given current density, and the appearance can be designed into any pattern. The monolithic membrane-based flexible supercapacitor prepared by this invention has the advantages of being ultra-lightweight, ultra-thin, having high specific capacitance, being able to withstand mechanical bending, and being able to be arbitrarily patterned. It holds great promise as a flexible energy storage device in the field of flexible portable electronic devices.

Claims

1. A monolithic membrane-based flexible supercapacitor, characterized in that: The supercapacitor includes a nylon filter membrane and sodium carboxymethyl cellulose / phytic acid / polyaniline membranes formed on the upper and lower surfaces of the nylon filter membrane, wherein triammonium dihydrogen disulfate is adsorbed in the nylon filter membrane; the supercapacitor uses the nylon filter membrane as a diaphragm and electrolyte storage layer, the sodium carboxymethyl cellulose / phytic acid / polyaniline membranes as positive and negative electrodes, and the triammonium dihydrogen disulfate adsorbed in the nylon filter membrane as an electrolyte.

2. The monolithic membrane-based flexible supercapacitor according to claim 1, characterized in that: The thickness of a single side of the sodium carboxymethyl cellulose / phytic acid / polyaniline film is 5 to 55 μm, and the total thickness of the supercapacitor is 110 to 210 μm.

3. The monolithic membrane-based flexible supercapacitor according to claim 1, characterized in that: The supercapacitor has a unit area weight as low as 0.28 g / cm 2 the following.

4. The monolithic membrane-based flexible supercapacitor according to claim 1, characterized in that: The sodium carboxymethyl cellulose / phytic acid / polyaniline film is composed of nanoparticles with an average size of 200 to 300 nm, and the nanoparticles are in a mutually adhered superimposed structure.

5. A method for preparing a monolithic membrane-based flexible supercapacitor according to any one of claims 1 to 4, characterized in that: The steps are as follows: 1) dissolving sodium carboxymethyl cellulose and phytic acid in water and stirring to obtain a sodium carboxymethyl cellulose / phytic acid colloidal solution; 2) adding aniline monomer to the sodium carboxymethyl cellulose / phytic acid colloidal solution and stirring to obtain a sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution; 3) preparing an aqueous solution of ammonium persulfate as an initiator; 4) The sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution and the ammonium persulfate aqueous solution are kept warm at 0-5°C; the ammonium persulfate aqueous solution is then added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution under high-speed stirring, and the solution is then allowed to stand in a dark environment at 0-5°C to allow the polymerization reaction to continue; after completion of the reaction, a dark green sodium carboxymethyl cellulose / phytic acid / polyaniline ink is obtained; 5) applying the ink to both sides of the nylon filter membrane by double-sided drop coating and drying; The monolithic film-based flexible supercapacitor is obtained.

6. The method for preparing a monolithic membrane-based flexible supercapacitor according to claim 5, characterized in that: In step 1), the mass percentage of sodium carboxymethyl cellulose in water is 1-2 wt.%, and the concentration of phytic acid dissolved in water is 0.00011±0.00001 mol mL -1 ; Step 2) The concentration of aniline monomer in the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution is 0.000483±0.00001 mol mL -1 ; In step 3), an aqueous ammonium persulfate solution was prepared by dissolving 1.212±0.003 g of ammonium persulfate in 5±0.5 mL of water; When the ammonium persulfate aqueous solution is added to the sodium carboxymethyl cellulose / phytic acid / aniline monomer colloidal solution in step 4), the molar ratio of ammonium persulfate to aniline monomer is 1.1:

1.

7. The method for preparing a monolithic membrane-based flexible supercapacitor according to claim 5, characterized in that: In step 4), during the process of adding the ammonium persulfate aqueous solution under high-speed stirring, the reaction system temperature is 0-5° C., the high-speed stirring speed is 400-500 rpm, and the high-speed stirring time is 2 min ± 10 s to form a uniformly dispersed sodium carboxymethyl cellulose / phytic acid / polyaniline ink; In step 4), the polymerization reaction is allowed to stand for 24 to 36 hours.

8. The method for preparing a monolithic membrane-based flexible supercapacitor according to claim 5, characterized in that: The ink drop coating amount on one side in step 5) is 36-76 μL cm -2 The drying environment after applying the ink is at a temperature of 25-27°C and a humidity of 54-60%, and the drying time is 3±1h.

9. The method for preparing a monolithic membrane-based flexible supercapacitor according to claim 5, characterized in that: During the drop coating in step 5), the mask with the hollow pattern is placed on the nylon filter membrane, and then the drop coating operation is performed to obtain a monolithic membrane-based flexible supercapacitor having the shape of the hollow pattern of the mask.

10. Application of the monolithic membrane-based flexible supercapacitor according to any one of claims 1 to 3, characterized in that: The supercapacitor is applied to flexible energy storage devices and has a high capacitance at 0.6 mA cm -2 The area specific capacitance under current density can reach 757mFcm -2 Above, the volumetric capacitance can reach 37.8F cm -3 Above; at 1mA cm -2 The capacitance retention rate can reach more than 112% after 2000 charge and discharge cycles at the current density of 0.8 mA cm -2 Under current density, the capacitance retention rate can reach more than 98% after repeated bending from 0 to 180 degrees 2000 times, and the appearance can be designed into any pattern.

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