Interdigital flexible supercapacitor and preparation method and application thereof

Abstract

The invention relates to an interdigital flexible supercapacitor and a preparation method and application thereof. The interdigital flexible supercapacitor comprises a flexible substrate layer, a middle layer and a flexible protection layer which are stacked in sequence, the middle layer comprises an interdigital electrode and a gel electrolyte, and the interdigital electrode comprises graphene-based conductive yarn interdigitals distributed on the flexible substrate layer in an array staggered mode and outgoing lines on the two sides; the gel electrolyte is filled between graphene-based conductive yarn interdigitals, and a gap is formed between the gel electrolyte and the outgoing line. Through the interdigital electrode structure design, the supercapacitor with good flexibility and high capacitance performance is prepared, the used electrode material is the conductive yarn, the conductive yarn has the advantages of being easy to obtain and low in cost, and the yarn material is easy to bend and also serves as an ideal material of the flexible supercapacitor; good capacitance performance can be kept under the bending condition, and a new strategy is provided for development of the fields of intelligent wearable equipment, artificial intelligence, flexible energy storage and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to an interdigital flexible supercapacitor and a preparation method and application thereof. Background Art

[0002] At present, flexible wearable sensors have been widely used in smart textiles, but how to provide energy for flexible sensors is an urgent problem to be solved. The main energy storage devices, such as batteries, capacitors, photovoltaic panels, etc., are mostly made of rigid materials. Even if they are miniaturized and integrated into fabric tissues, it is difficult to give full play to the advantages of flexible wearable devices. Therefore, designing and developing flexible energy storage devices to provide energy for flexible wearable sensors will strongly promote the development of integrated flexible smart wearable devices.

[0003] In addition, compared with ordinary capacitors, supercapacitors have the electrochemical structure of the Helmholtz layer and have higher energy density and power density. Flexible supercapacitors have excellent flexibility, high energy density and high power density, and are easy to integrate with flexible wearable sensors, and have broad application prospects in powering flexible wearable sensors. For example, the patent document with publication number CN116564716A discloses a flexible asymmetric supercapacitor and a preparation method thereof, but because it uses asymmetric electrode materials to optimize the performance of the supercapacitor, this means that different electrodes need to be prepared, and the preparation process is complicated and the cost is high. Based on the above considerations, it is urgent to develop a simpler and easier-to-operate method to improve the flexibility and energy density of supercapacitors, so as to better adapt to the rapid development of flexible energy storage devices and flexible wearable sensors. Summary of the invention

[0004] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide an interdigital flexible supercapacitor and a preparation method and application thereof that meet one or more of the aforementioned needs.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] A finger-type flexible supercapacitor comprises a flexible substrate layer, an intermediate layer and a flexible protective layer stacked in sequence, the intermediate layer comprises finger-type electrodes and a gel electrolyte, the finger-type electrodes comprise graphene-based conductive yarn fingers staggeredly distributed in an array on the flexible substrate layer and lead wires on both sides; the gel electrolyte is filled between the graphene-based conductive yarn fingers, and there is a gap between the gel electrolyte and the lead wires.

[0007] As a preferred embodiment, the graphene-based conductive yarn is a graphene-polyimide composite yarn, a graphene-aramid composite yarn, a graphene-polyester composite yarn or a graphene-cotton composite yarn.

[0008] As a preferred embodiment, the preparation process of the graphene-polyimide composite yarn comprises the following steps:

[0009] (1) preparing a graphene oxide solution with a concentration of 1 to 10 mg / mL;

[0010] (2) coating the base yarn with graphene oxide;

[0011] (3) The graphene oxide coated substrate yarn is reduced with hydroiodic acid and then subjected to thermal reduction treatment to obtain a graphene-polyimide composite yarn.

[0012] As a preferred embodiment, in step (3), the temperature of the hydroiodic acid reduction is 30 to 100° C., and the reduction time is 10 to 120 min;

[0013] The temperature of thermal reduction is 200-300°C, and the reduction time is 5-20h.

[0014] As a preferred embodiment, the diameter of the graphene-based conductive yarn fingers is 100-600 μm, the length is 2-10 cm, the spacing between adjacent graphene-based conductive yarn fingers is 0.5-2 mm, and the coverage length of the gel electrolyte on the surface of the graphene-based conductive yarn fingers is 1.5-9.5 cm.

[0015] As a preferred solution, the gel electrolyte is one of PVA-H2SO4, PVA-KOH, and PVA-NaSO4.

[0016] As a preferred solution, the lead wire is a conductive wire or a conductive metal glue.

[0017] As a preferred solution, the thickness of the interdigital flexible supercapacitor is 1 to 10 mm.

[0018] The present invention also provides a method for preparing an interdigital flexible supercapacitor as described in any of the above schemes, comprising the following steps:

[0019] S1, curing the PDMS pre-curing solution into a flexible substrate layer in a mold;

[0020] S2, arranging the graphene-based conductive yarn fingers on the flexible substrate layer in a staggered manner, connecting the two ends of the graphene-based conductive yarn fingers to the lead wires on both sides in an intermittent manner, and coating the connection with conductive silver paste; wherein the lead-out parts of the lead wires serve as the positive and negative electrodes of the supercapacitor;

[0021] S3, dripping the electrolyte solution onto the graphene-based conductive yarn interdigitated on the surface of the flexible substrate layer in step S2, and after the electrolyte is naturally cured, dripping the PDMS pre-curing solution onto the surface to cover the entire interdigitated electrode, and then naturally curing to obtain an interdigitated flexible supercapacitor.

[0022] The present invention also provides a flexible energy storage device, comprising the interdigital flexible supercapacitor as described in any of the above schemes.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention prepares a supercapacitor with good flexibility and high capacitance performance through the design of the interdigital electrode structure, and the electrode material used is conductive yarn, which is easy to obtain and low cost, and the yarn material is easy to bend, and is also an ideal material for flexible supercapacitors. In addition, the interdigital structural design can integrate more electrodes per unit area, thereby improving the capacitance of the supercapacitor and the stability during use. Finally, the flexible interdigital supercapacitor of the present invention can also maintain good capacitance performance under bending conditions, providing a new strategy for the development of smart wearable devices, artificial intelligence, flexible energy storage and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic structural diagram of an interdigital flexible supercapacitor according to Example 1 of the present invention;

[0026] Figure 2 This is a physical picture of the interdigital flexible supercapacitor of Example 1 of the present invention;

[0027] Figure 3 CV curves of the interdigital flexible supercapacitor of Example 1 of the present invention under bending conditions and at scan rates of 300 mV / s and 500 mV / s;

[0028] Figure 4 This is a charge and discharge curve diagram of the interdigital flexible supercapacitor of Example 1 of the present invention under bending conditions and a current intensity of 1 mA. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the embodiments of the present invention, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings and other implementation methods can be obtained based on these accompanying drawings without creative work.

[0030] Embodiment 1:

[0031] like Figure 1As shown, the interdigital flexible supercapacitor of this embodiment comprises, from top to bottom, an upper flexible protective layer 10 , an interdigital electrode 20 , a gel electrolyte 30 , and a lower flexible substrate layer 40 .

[0032] The interdigitated electrode 20 includes graphene-polyimide composite yarn interdigitated in an array and distributed on a flexible substrate layer and copper glue electrodes 50 on both sides. The structural distribution of the interdigitated electrode 20 can refer to the prior art and will not be described here. The gel electrolyte 30 is filled between the graphene-polyimide composite yarn interdigitated fingers, and there is a gap between the gel electrolyte 30 and the copper glue electrode 50.

[0033] The method for preparing the interdigital flexible supercapacitor of this embodiment comprises the following steps:

[0034] (1) preparing a graphene oxide aqueous solution with a concentration of 8 mg / mL and pouring it into a spinning tank, a polyimide yarn with a fineness of 20 s passes through the spinning tank and is loaded with the graphene oxide solution, and this process is repeated 6 times to obtain a graphene oxide-coated polyimide yarn;

[0035] (2) placing the yarn obtained in step (1) into a hydration reactor containing hydroiodic acid and reducing it at 30° C. for 40 min, then repeatedly washing and drying the chemically reduced yarn and placing it into a muffle furnace for further reduction at 300° C. for 8 h to obtain a conductive yarn, i.e., a graphene-polyimide composite yarn; the conductive yarn is used as an electrode of a supercapacitor;

[0036] (3) The prepared PDMS solution (containing a curing agent, which can be specifically referred to in the prior art and will not be described in detail here) is evenly dripped into a mold of 7 cm in length and 3 cm in width using a pipette, and cured at 60° C. for 2 h to obtain a flexible substrate layer with a thickness of about 3 mm;

[0037] (4) A double-sided conductive copper glue with a width of 1 cm is pasted on both sides of the flexible substrate layer, and the conductive copper glue has an extra 2 cm above and below as the positive and negative electrodes of the supercapacitor; then, a conductive yarn electrode with a diameter of 200 μm and a length of 2.3 cm is connected to the double-sided copper glue in the form of interdigitated fingers, and conductive silver glue is dripped at the connection to prevent poor contact; wherein, the spacing between adjacent conductive yarns is 1 mm;

[0038] (5) Dissolve 10 g of PVA in 90 mL of deionized water and completely dissolve at 90° C. After cooling to room temperature, slowly add 10 mL of concentrated sulfuric acid and stir thoroughly to obtain a PVA-H2SO4 gel electrolyte. Apply the prepared electrolyte to the conductive yarn electrode obtained in step (4) with a syringe so that the length of the electrolyte covering the electrode is 2.2 cm. Ensure that there is a gap of 1 mm between the gel electrolyte and the conductive copper glue, and then let it stand and wait for the gel electrolyte to solidify;

[0039] (6) Using a pipette, drop the PDMS solution onto the electrode surface obtained in step (5) so that the PDMS solution can evenly cover the entire main body of the supercapacitor. Finally, wait for the PDMS to solidify to form a flexible protective layer, thereby obtaining an interdigitated flexible supercapacitor. The local structure of the interdigitated flexible supercapacitor is shown in FIG. Figure 2 As shown; the thickness of the interdigital flexible supercapacitor is 8 mm, and the thickness can also be adjusted according to actual application requirements.

[0040] The interdigital flexible supercapacitor of this embodiment was tested as follows:

[0041] The flexible supercapacitor obtained in this embodiment was tested using a Shanghai Chenhua electrochemical workstation. During the test, the supercapacitor was folded 180°. Its cyclic voltammetry curves at scan rates of 300 mV / s and 500 mV / s were as follows: Figure 3 As shown, it can be seen that at the two scanning rates, the cyclic voltammetry curves of the interdigital flexible supercapacitor in this embodiment show a typical rectangular shape, which indicates that it has a double-layer charging and discharging characteristic, indicating that bending in half does not affect the capacitance effect of the supercapacitor in this embodiment, that is, it can be used well as a flexible energy storage device.

[0042] In addition, the charge and discharge curves at a current intensity of 1 mA are as follows Figure 4 As shown, the charge and discharge curve of the interdigitated flexible supercapacitor in this embodiment is close to an isosceles triangle, indicating its good charge and discharge stability. At the same time, at a current of 1 mA, each charge and discharge cycle time is only 1.2 s, indicating that the two-step reduction method makes the conductive yarn electrode have a lower resistance.

[0043] Embodiment 2:

[0044] The interdigital flexible supercapacitor of this embodiment is different from that of Embodiment 1 in that:

[0045] The interdigitated graphene-polyimide composite yarn can be replaced by graphene-aramid composite yarn, graphene-polyester composite yarn or graphene-cotton composite yarn;

[0046] For other details, please refer to Example 1.

[0047] Embodiment 3:

[0048] The interdigital flexible supercapacitor of this embodiment is different from that of Embodiment 1 in that:

[0049] The gel electrolyte can be replaced by one of PVA-KOH and PVA-NaSO4;

[0050] For other details, please refer to Example 1.

[0051] Embodiment 4:

[0052] The interdigital flexible supercapacitor of this embodiment is different from that of Embodiment 1 in that:

[0053] The copper glue electrodes can be replaced with wires;

[0054] For other details, please refer to Example 1.

[0055] Embodiment 5:

[0056] The preparation method of the interdigital flexible supercapacitor of this embodiment is different from that of Embodiment 1 in that:

[0057] The process indicators involved in each process step can be selected within a limited range according to actual application requirements;

[0058] For other details, please refer to Example 1.

[0059] In view of the numerous embodiments of the scheme of the present invention, the raw materials and dosage involved can be selected according to actual needs within the limited range, and the experimental data of each embodiment is huge and numerous, which is not suitable for listing and explaining one by one here, but the content required to be verified and the final conclusion obtained in each embodiment are similar. Therefore, the verification content of each embodiment will not be explained one by one here.

[0060] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. An interdigital flexible supercapacitor, characterized in that: It includes a flexible substrate layer, an intermediate layer and a flexible protective layer stacked in sequence. The intermediate layer includes interdigitated electrodes and a gel electrolyte. The interdigitated electrodes include graphene-based conductive yarn interdigitated arrays and lead wires on both sides. The gel electrolyte is filled between the graphene-based conductive yarn interdigitated fingers, and there is a gap between the gel electrolyte and the lead wires.

2. The interdigital flexible supercapacitor according to claim 1, characterized in that: The graphene-based conductive yarn is interdigitated into graphene-polyimide composite yarn, graphene-aramid composite yarn, graphene-polyester composite yarn or graphene-cotton composite yarn.

3. The interdigital flexible supercapacitor according to claim 2, characterized in that: The preparation process of the graphene-polyimide composite yarn comprises the following steps: (1) preparing a graphene oxide solution with a concentration of 1 to 10 mg / mL; (2) coating the base yarn with graphene oxide; (3) The graphene oxide coated substrate yarn is reduced with hydroiodic acid and then subjected to thermal reduction treatment to obtain a graphene-polyimide composite yarn.

4. The interdigital flexible supercapacitor according to claim 3, characterized in that: In the step (3), the temperature of the hydroiodic acid reduction is 30 to 100° C., and the reduction time is 10 to 120 min; The temperature of thermal reduction is 200-300°C, and the reduction time is 5-20h.

5. The interdigital flexible supercapacitor according to claim 1, characterized in that: The diameter of the graphene-based conductive yarn fingers is 100-600 μm, the length is 2-10 cm, the spacing between adjacent graphene-based conductive yarn fingers is 0.5-2 mm, and the coverage length of the gel electrolyte on the surface of the graphene-based conductive yarn fingers is 1.5-9.5 cm.

6. The interdigital flexible supercapacitor according to claim 1, characterized in that: The gel electrolyte is one of PVA-H2SO4, PVA-KOH and PVA-NaSO4.

7. The interdigital flexible supercapacitor according to claim 1, characterized in that: The lead wire is a conductive wire or a conductive metal glue.

8. The interdigital flexible supercapacitor according to claim 1, characterized in that: The thickness of the interdigital flexible supercapacitor is 1 to 10 mm.

9. The method for preparing an interdigital flexible supercapacitor according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, curing the PDMS pre-curing solution into a flexible substrate layer in a mold; S2, arranging the graphene-based conductive yarn fingers on the flexible substrate layer in a staggered manner, connecting the two ends of the graphene-based conductive yarn fingers to the lead wires on both sides in an intermittent manner, and coating the connection with conductive silver paste; wherein the lead-out parts of the lead wires serve as the positive and negative electrodes of the supercapacitor; S3, dripping the electrolyte solution onto the graphene-based conductive yarn interdigitated on the surface of the flexible substrate layer in step S2, and after the electrolyte is naturally cured, dripping the PDMS pre-curing solution onto the surface to cover the entire interdigitated electrode, and then naturally curing to obtain an interdigitated flexible supercapacitor.

10. A flexible energy storage device, characterized in that: It comprises an interdigital flexible supercapacitor as described in any one of claims 1 to 8.

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