Water-based carbon-based printing ink and preparation method thereof, flexible supercapacitor electrode and flexible supercapacitor

Abstract

The invention belongs to the technical field of flexible supercapacitors, and relates to water-based carbon-based printing ink and a preparation method thereof, a flexible supercapacitor electrode and a flexible supercapacitor. The invention provides water-based carbon-based printing ink. The water-based carbon-based printing ink is prepared from the following raw materials in parts by weight: 20-35 parts of a two-dimensional lamellar carbon material, 10-30 parts of a conductive polymer material, 0.05-0.3 part of polyvinylpyrrolidone and 40-70 parts of a solvent. The two-dimensional lamellar carbon material is at least one of expanded graphite flakes and graphene, and the two-dimensional lamellar carbon material is subjected to heat treatment.

Description

Technical Field

[0001] The present invention relates to the field of flexible supercapacitors, and in particular to a water-based carbon-based printing ink and a preparation method thereof, a flexible supercapacitor electrode and a flexible supercapacitor. Background Art

[0002] With the continuous advancement of electronic technology, more and more electronic devices are moving towards being thinner, more flexible and wearable, which not only improves the portability and comfort of the equipment, but also expands its application potential in medical health monitoring, smart clothing and other fields. However, under this trend, the development of corresponding thinner and more flexible energy storage devices has become one of the biggest challenges. An ideal flexible energy storage device should be able to adapt to a variety of deformation states such as bending and folding, while maintaining efficient energy storage and release capabilities. In this context, flexible supercapacitors stand out due to their unique performance advantages and have become an important research object in the field of flexible energy storage. They not only have a large power density and support fast charging and discharging, but also exhibit a long cycle life and good stability. These characteristics make flexible supercapacitors an ideal power solution for flexible electronic products.

[0003] In order to further improve the performance of flexible supercapacitors, especially to increase their operating voltage range, researchers are committed to developing printed flexible supercapacitors with high voltage windows. The realization of this goal involves technical innovations in many aspects, including the development of ink materials suitable for printing processes, the selection of high-voltage resistant electrolytes, and the optimization of manufacturing processes. Specifically, the ink used to make supercapacitors must contain active materials that can work stably at high voltages while maintaining good conductivity and adhesion to ensure the smooth progress of the printing process and the performance of the final product. Researchers are gradually overcoming technical barriers to promote the development of high-voltage window flexible supercapacitors, providing strong support for more intelligent and personalized electronic devices in the future.

[0004] The existing preparation process of flexible supercapacitors is costly and complicated. For example, patent CN103923529B discloses a method for preparing flexible supercapacitors using composite ink. The patent uses metal oxides as pseudocapacitor materials to improve the specific capacity of the monomer. However, due to the characteristics of metal oxides, the voltage window of the monomer supercapacitor is low, so it is more limited in circuit applications with higher voltage requirements. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a water-based carbon-based printing ink and a preparation method thereof, a flexible supercapacitor electrode and a flexible supercapacitor, which solves the technical problem that the existing supercapacitor printing ink is difficult to meet the requirements of high-voltage circuits.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a water-based carbon-based printing ink, which is prepared from the following raw materials in parts by weight: 20-35 parts of two-dimensional carbon sheet material, 10-30 parts of conductive polymer material, 0.05-0.3 parts of polyvinyl pyrrolidone and 40-70 parts of solvent. The two-dimensional carbon sheet material is at least one of expanded graphite sheet and graphene.

[0007] The two-dimensional flaky carbon material is subjected to heat treatment, specifically comprising the following steps: in a nitrogen atmosphere, the two-dimensional flaky carbon material is heated from room temperature to 280°C to 320°C at a rate of 10°C / min to 15°C / min, kept warm for 25min to 35min, then heated to 780°C to 820°C at a rate of 5°C / min to 8°C / min, kept warm for 55min to 65min, and finally heated to 950°C to 1050°C at a rate of 1°C / min to 3°C / min, and kept warm for 1h to 3h.

[0008] The present invention utilizes heat treatment to significantly improve the dispersibility, stability and high-voltage resistance of two-dimensional flaky carbon materials, avoids agglomeration, improves the stability of ink and printing quality, reduces defects and impurities, makes it more stable in a high-voltage environment, prevents electrochemical decomposition and performance degradation, thereby improving the electrochemical performance of supercapacitors, especially improving the voltage window of supercapacitors, and solving the technical problem that existing supercapacitor printing inks are difficult to meet the requirements of high-voltage circuits.

[0009] Optionally, the two-dimensional carbon sheet material has a sheet diameter of >5µm and an electrical conductivity of >450s / cm.

[0010] Optionally, the conductive polymer material is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate.

[0011] Poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate and two-dimensional lamellar carbon material form a three-dimensional conductive network through π~π intermolecular bonding. This network structure not only significantly improves the conductivity of the material, but also enhances the mechanical stability and electrochemical properties of the electrode. After printing and forming a film, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate is heated and cross-linked to form a stable three-dimensional conductive film with the two-dimensional lamellar carbon material. The π~π interaction provides abundant conductive paths, allowing electrons to be efficiently transmitted within the material, thereby improving the conductivity and electrochemical activity of the electrode material. The cross-linked poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate enhances the connection between molecules, forms a more stable network structure, and further improves the mechanical stability and durability of the electrode material. This synergistic effect enables the electrode material to efficiently carry out electrochemical reactions during the charging and discharging process, thereby improving the capacitance and energy density of the capacitor, while having the characteristics of fast charging and discharging and long cycle life.

[0012] Optionally, the solvent is water and dimethyl sulfoxide in a mass ratio of 1:0.1-0.5.

[0013] The present invention uses a mixed solvent of water and dimethyl sulfoxide in a mass ratio of 1:0.1-0.5 to effectively disperse hydrophilic carbon materials and conductive polymers, and improve the dispersibility and uniformity of the materials. Dimethyl sulfoxide, as a high-boiling point, high-polarity solvent, has excellent solubility and dispersibility, can effectively disperse hydrophobic carbon materials and conductive polymers, prevent agglomeration, and enhance the stability and long-term storage performance of the ink. The mixed solvent can balance the characteristics of the two, improve the conductivity and printing performance of the ink, and ensure that the ink can be uniformly deposited on the substrate during the printing process to form a uniform electrode layer.

[0014] In addition, the addition of water can control the drying speed of the ink and avoid cracks and unevenness caused by too fast drying, while the high boiling point of dimethyl sulfoxide can prevent the ink from drying prematurely during the printing process, ensuring the printing quality and the integrity of the electrode. These advantages make the prepared flexible supercapacitors have high power density, fast charging and discharging, long cycle life and good mechanical flexibility, which are very suitable for application in future flexible electronic devices.

[0015] The present invention provides a method for preparing the above-mentioned water-based carbon-based printing ink, comprising the following steps: The heat-treated two-dimensional flaky carbon material is dispersed evenly in a solvent system to obtain a two-dimensional flaky carbon material dispersion; the conductive polymer material and the two-dimensional flaky carbon material dispersion are mixed evenly to obtain a suspension; and polyvinyl pyrrolidone and the suspension are mixed evenly to obtain a water-based carbon-based printing ink.

[0016] The present invention provides a method for preparing a flexible supercapacitor electrode, which uses the above-mentioned water-based carbon-based printing ink, prints the water-based carbon-based printing ink on a substrate, and forms a flexible supercapacitor electrode on the surface of the substrate.

[0017] Optionally, the substrate includes at least one of polyethylene terephthalate, polyimide and polyethylene naphthalate.

[0018] Optionally, the printing method is any one of screen printing, gravure printing and flexographic printing.

[0019] The present invention provides a flexible supercapacitor electrode, which is prepared by adopting the above-mentioned method for preparing the flexible supercapacitor electrode.

[0020] The present invention provides a flexible supercapacitor, comprising the flexible supercapacitor electrode.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention utilizes heat treatment to significantly improve the dispersibility, stability and high-voltage resistance of two-dimensional carbon sheet materials, avoid agglomeration, improve the stability of ink and printing quality, reduce defects and impurities, make it more stable in a high-voltage environment, prevent electrochemical decomposition and performance degradation, thereby improving the electrochemical performance of supercapacitors, especially improving the voltage window of supercapacitors, and solving the technical problem that existing supercapacitor printing inks are difficult to meet the requirements of high-voltage circuits.

[0022] 2. The present invention uses two-dimensional sheet carbon materials with high conductivity and large specific surface area, providing more active sites, enhancing the contact area of ​​electrochemical reactions, and further improving the capacitance and energy density of the capacitor. When the aqueous carbon-based printing ink is printed as an electrode, it has excellent mechanical properties, high elasticity and good flexibility, making the electrode material less likely to break during bending and folding, and enhancing the mechanical stability and durability of the flexible supercapacitor. These advantages make the prepared flexible supercapacitor have high power density, fast charging and discharging, long cycle life and good mechanical flexibility, which is very suitable for application in future flexible electronic devices.

[0023] 3. The water-based carbon-based printing ink of the present invention utilizes the combination of two-dimensional flaky carbon materials and conductive polymer materials. When printing electrodes, a highly conductive conductive network is formed inside the flexible supercapacitor electrode, so that electrons are efficiently transmitted inside the electrode material, thereby improving the conductivity and electrochemical activity of the electrode material. As a result, the flexible supercapacitor electrode does not require a current collector to meet the conductive properties, thereby simplifying the structure and preparation process of the flexible supercapacitor electrode, which is conducive to the mass industrial production and application of flexible supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of a series supercapacitor electrode module printed on a PET substrate by screen printing in the process of preparing a supercapacitor using the water-based carbon-based printing ink prepared in Example 1.

[0025] Figure 2 Schematic diagram of attaching a thin film having an electrode shape to the electrode surface during the process of preparing a supercapacitor using the water-based carbon-based printing ink prepared in Example 1.

[0026] Figure 3 Schematic diagram of the release film removed from the attachment layer covering the electrode surface during the process of preparing a supercapacitor using the water-based carbon-based printing ink prepared in Example 1. DETAILED DESCRIPTION

[0027] In order to solve the above technical problems, the present invention provides a water-based carbon-based printing ink and a preparation method thereof, a flexible supercapacitor electrode and a flexible supercapacitor. The technical scheme and embodiments of the present invention are now described in detail in conjunction with the accompanying drawings.

[0028] The present invention is described in detail below through specific examples. The examples are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0029] Embodiment 1: S1. Prepare the following raw materials in parts by mass: 30 parts of two-dimensional carbon sheet material, 18 parts of conductive polymer material, 0.15 parts of polyvinyl pyrrolidone, and 50 parts of solvent.

[0030] Among them, the two-dimensional lamellar carbon material is an expanded graphite sheet with an average sheet diameter of 8µm and an electrical conductivity of 520s / cm, and the graphite sheet is heat-treated, specifically, in a nitrogen atmosphere, the graphite sheet is heated from room temperature to 290°C at a rate of 12°C / min, kept warm for 30 minutes, then heated at 6°C / min to 810°C, kept warm for 60 minutes, and finally heated to 1000°C at 2°C / min and kept warm for 2 hours.

[0031] The conductive polymer material is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate purchased from Heraeus.

[0032] The solvent is water and dimethyl sulfoxide in a mass ratio of 1:0.1.

[0033] S2. Add the two-dimensional carbon sheet material into a solvent for ultrasonic dispersion, and then add a conductive polymer material and stir to obtain a suspension; wherein the ultrasonic power during the ultrasonic dispersion process is 300 W, the frequency is 25 kHz, and the time is 45 min.

[0034] S3. Finally, polyvinyl pyrrolidone is added and stirred to obtain a water-based carbon-based printing ink.

[0035] Embodiment 2: S1. Prepare the following raw materials in parts by mass: 20 parts of two-dimensional carbon sheet material, 10 parts of conductive polymer material, 0.05 parts of polyvinyl pyrrolidone, and 40 parts of solvent.

[0036] Among them, the two-dimensional lamellar carbon material is an expanded graphite sheet with an average sheet diameter of 8µm and an electrical conductivity of 520s / cm, and the graphite sheet is heat-treated, specifically, in a nitrogen atmosphere, the graphite sheet is heated from room temperature to 290°C at a rate of 12°C / min, kept warm for 30 minutes, then heated at 6°C / min to 810°C, kept warm for 60 minutes, and finally heated to 1000°C at 2°C / min and kept warm for 2 hours.

[0037] The conductive polymer material is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate purchased from Heraeus.

[0038] The solvent is water and dimethyl sulfoxide in a mass ratio of 1:0.3.

[0039] S2. Add the two-dimensional carbon sheet material into a solvent for ultrasonic dispersion, and then add a conductive polymer material and stir to obtain a suspension; wherein the ultrasonic power during the ultrasonic dispersion process is 300 W, the frequency is 25 kHz, and the time is 45 min.

[0040] S3. Finally, polyvinyl pyrrolidone is added and stirred to obtain a water-based carbon-based printing ink.

[0041] Embodiment 3: S1. Prepare the following raw materials in parts by weight: 35 parts of two-dimensional carbon sheet material, 30 parts of conductive polymer material, 0.3 parts of polyvinyl pyrrolidone, and 70 parts of solvent; Among them, the two-dimensional lamellar carbon material is an expanded graphite sheet with an average sheet diameter of 8µm and an electrical conductivity of 520s / cm, and the graphite sheet is heat-treated, specifically, in a nitrogen atmosphere, the graphite sheet is heated from room temperature to 290°C at a rate of 12°C / min, kept warm for 30 minutes, then heated at 6°C / min to 810°C, kept warm for 60 minutes, and finally heated to 1000°C at 2°C / min and kept warm for 2 hours.

[0042] The conductive polymer material is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate purchased from Heraeus.

[0043] The solvent is water and dimethyl sulfoxide in a mass ratio of 1:0.5.

[0044] S2. Add the two-dimensional carbon sheet material into a solvent for ultrasonic dispersion, and then add a conductive polymer material and stir to obtain a suspension; wherein the ultrasonic power during the ultrasonic dispersion process is 300 W, the frequency is 25 kHz, and the time is 45 min.

[0045] S3. Finally, polyvinyl pyrrolidone is added and stirred to obtain a water-based carbon-based printing ink.

[0046] Embodiment 4: The only difference from Example 1 is that the two-dimensional carbon sheet material is not heat treated.

[0047] Embodiment 5: The only difference from Example 1 is that during the heat treatment of the two-dimensional carbon sheet material, the temperature is raised from room temperature to 1000° C. at a rate of 10 to 15° C. / min and kept at this temperature for 2 hours.

[0048] Embodiment 6: The only difference from Example 1 is that the solvent is water.

[0049] Comparative Example 1: The only difference from Example 1 is that the amount of two-dimensional sheet carbon material added is 5 parts.

[0050] Comparative Example 2: The only difference from Example 1 is that the amount of two-dimensional layered carbon material added is 45 parts.

[0051] The water-based carbon-based printing inks prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were Figure 1 As shown in FIG. 1 , a series supercapacitor electrode module is printed on a PET substrate by screen printing, and then dried at 90°C, and then Figure 2 As shown in the figure, a film with an electrode shape is attached to the electrode surface to form a groove, and a gel electrolyte is applied. Figure 3 As shown, the release film on the attachment layer covering the electrode surface is removed, and finally a flexible, high-voltage-resistant supercapacitor is obtained by encapsulating it with LiTFSI electrolyte.

[0052] Table 1: Performance test results of supercapacitors prepared using water-based carbon-based printing inks prepared in Examples 1 to 6 and Comparative Examples 1 to 2 In summary, the water-based carbon-based printing ink of the present invention adopts two-dimensional flaky carbon materials with high conductivity and large specific surface area and significantly improves the dispersibility and stability of the material through multi-stage heat treatment, avoids agglomeration, improves the stability of the ink and printing quality, and also has excellent mechanical properties, so that the electrode is not easy to break during bending and folding, thereby enhancing the mechanical stability and durability of the flexible supercapacitor.

[0053] The parts of the embodiments herein that are not exhaustive of the midpoint values ​​of the technical scope claimed for protection by the present invention and the new technical solutions formed by equivalent replacement of single or multiple technical features in the technical solutions of the embodiments are also within the scope claimed for protection by the present invention; at the same time, in all the listed or unlisted embodiments of the scheme of the present invention, each parameter in the same embodiment merely represents an example of its technical solution (i.e., a feasible solution), and there is no strict coordination and limitation relationship between the parameters, wherein the parameters can be replaced with each other without violating the axioms and the claims of the present invention, unless otherwise stated.

[0054] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above technical means, but also include technical schemes composed of any combination of the above technical features. The above is a specific implementation of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

[0055] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A water-based carbon-based printing ink, characterized in that: Made from the following raw materials in parts by weight: 20-35 parts of two-dimensional sheet carbon material, 10-30 parts of conductive polymer material, 0.05-0.3 parts of polyvinyl pyrrolidone and 40-70 parts of solvent; The two-dimensional sheet carbon material is at least one of expanded graphite sheet and graphene; The two-dimensional carbon sheet material is subjected to heat treatment, which specifically comprises the following steps: In a nitrogen atmosphere, the two-dimensional lamellar carbon material is heated from room temperature to 280°C~320°C at a rate of 10°C / min~15°C / min, kept warm for 25min~35min, then heated to 780°C~820°C at 5°C / min~8°C / min, kept warm for 55min~65min, and finally heated to 950°C~1050°C at 1°C / min~3°C / min, and kept warm for 1h~3h.

2. The water-based carbon-based printing ink according to claim 1, characterized in that: The two-dimensional carbon sheet material has a sheet diameter of >5µm and an electrical conductivity of >450s / cm.

3. The water-based carbon-based printing ink according to claim 1, characterized in that: The conductive polymer material is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate.

4. The water-based carbon-based printing ink according to claim 1, characterized in that: The solvent is water and dimethyl sulfoxide in a mass ratio of 1:0.1-0.

5.

5. A method for preparing the water-based carbon-based printing ink according to any one of claims 1 to 4, characterized in that: The following steps are involved: The heat-treated two-dimensional carbon sheet material is uniformly dispersed in a solvent system to prepare a two-dimensional carbon sheet material dispersion; The conductive polymer material and the two-dimensional carbon sheet material dispersion are uniformly mixed to prepare a suspension; The polyvinyl pyrrolidone and the suspension are uniformly mixed to prepare a water-based carbon-based printing ink.

6. A method for preparing a flexible supercapacitor electrode, characterized in that: The water-based carbon-based printing ink according to any one of claims 1 to 4 is used to print the water-based carbon-based printing ink on a substrate to form a flexible supercapacitor electrode on the surface of the substrate.

7. The method for preparing a flexible supercapacitor electrode according to claim 6, characterized in that: The substrate includes at least one of polyethylene terephthalate, polyimide and polyethylene naphthalate.

8. The method for preparing a flexible supercapacitor electrode according to claim 6, characterized in that: The printing method is any one of screen printing, gravure printing and flexographic printing.

9. A flexible supercapacitor electrode, characterized in that: The flexible supercapacitor electrode is prepared by the preparation method of any one of claims 6 to 8.

10. A flexible supercapacitor, characterized in that: Comprising the flexible supercapacitor electrode as claimed in claim 9.

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