CN113421778B - Flexible micro super capacitor and manufacturing method thereof - Google Patents

Abstract

The invention discloses a flexible micro super capacitor and a manufacturing method thereof, comprising the following steps: manufacturing a flexible substrate on a substrate; printing a female die by adopting an electric field driven jet deposition micro-nano 3D printing technology; depositing an electrode material on the master mold through an electrochemical polymerization process; uniformly coating a solid electrolyte on an electrode material; and sealing and manufacturing the flexible micro super capacitor. The low-cost batch manufacturing of the conductive high-molecular flexible miniature super capacitor is realized by combining the electric field driven jet deposition micro-nano 3D printing and electrochemical polymerization technology.

Description

A kind of flexible micro supercapacitor and its manufacturing method

technical field

The present application belongs to the field of 3D printing and energy, and in particular relates to a flexible micro supercapacitor and a manufacturing method thereof.

Background technique

With the rapid development of miniaturized, portable, and highly integrated flexible electronics, there is an increasing demand for miniature flexible power and energy storage units. It is widely used in portable wireless communication systems, MEMS, biological wireless sensors, multifunctional micro/nano systems, micro robots, and wearable/implantable medical devices. Micro-batteries are the main choice for fabricating miniature power systems, however, due to their disadvantages of low power density and short cycle life, their widespread application in microelectronic devices, especially in implantable electronic medical devices, is greatly limited. Therefore, new, miniature devices with high-efficiency energy storage are in urgent need of development.

In recent years, flexible micro-supercapacitors (MSCs) have gradually become ideal substitutes for micro-batteries due to their high power density, excellent cycle life, fast charge/discharge rates, and good mechanical properties, which have attracted attention in various fields. Special attention. Traditionally, microelectronic devices are powered by MSCs made of vertical sandwich structures, which can easily lead to short-circuiting of the top and bottom electrodes. To prevent device failure due to short circuits, a sufficiently thick active material must be filled between the two electrodes to ensure the necessary distance separation. However, this also increases ion transport resistance, thereby reducing the power density of the device. In addition, due to the high thickness of MSCs fabricated from vertical sandwich structures, it will be difficult to integrate into microelectronic devices. In contrast, in-plane MSCs with finger electrodes are based on a staggered structure, characterized by the fact that the finger electrodes and the current collector are in the same plane and isolated from each other by insulating gaps, which is more suitable for integrated circuits. High-molecular conductive polymers are commonly used in the field of supercapacitors due to their unique properties, such as high electrical conductivity, fast charge/discharge mechanism, good thermal stability and flexibility, low cost, and high energy density. electrode material. However, even with these advantages, challenges still exist, and the main problems are: First, the need to develop a high-resolution interdigital pattern fabrication technique to assemble electrode materials on a wearable flexible board that can be integrated with a small fixed area ( Maximum size: 1cm ² ) in the integration of other flexible electronic components. Second, it is difficult to make high-molecular conductive polymers into interdigitated structures, and they are often mixed with other materials, which greatly reduces their electrochemical performance. Third, it is necessary to fabricate an interdigitated structure with a large aspect ratio, so that the contact area between the electrode material and the electrolyte is larger, and the capacitance of the MSC is greatly improved in the effective unit area.

There are currently very limited fabrication processes for interdigitated flexible MSCs, such as photolithography, plasma etching, laser scribing, and inkjet printing methods. Although these conventional microfabrication methods have been successfully used in the fabrication of microdevices, their process flows are not easily integrated into specific flexible and wearable substrates, and most are only suitable for the preparation of interdigital electrodes with specific materials, The interdigitated structure has a low height and width ratio; some manufacturing processes require expensive facilities, expensive chemicals, and clean rooms, which have high requirements on the environment, and the manufacturing process is complex and inefficient, and it will also generate a lot of material waste and pollution. gas. These existing technologies or solutions have deficiencies and limitations in miniature, flexible, high-efficiency, low-cost, and mass manufacturing, which seriously affect and restrict the wider commercial application of interdigitated micro-flexible supercapacitors, which need to be developed urgently. Novel fabrication methods and strategies for efficient, low-cost, and large-scale fabrication of conductive polymer-based interdigitated micro-flexible supercapacitors.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present application proposes a flexible micro-supercapacitor and its manufacturing method, which combines electric field-driven jet deposition micro-nano 3D printing and electrochemical polymerization technology to achieve low-cost mass production of conductive polymer flexible micro-supercapacitors.

In order to achieve the above purpose, in some embodiments of the present application, the following technical solutions are adopted:

A manufacturing method of a flexible micro supercapacitor, comprising the following steps:

(1) Making a flexible substrate on the substrate;

(2) Using the electric field-driven jet deposition micro-nano 3D printing technology to print the master mold;

(3) depositing the electrode material on the master mold by an electrochemical polymerization process;

(4) uniformly coating the solid electrolyte on the electrode material;

(5) Sealing, making the preparation of flexible micro supercapacitors.

In some embodiments of the present application, in the step (1), the substrate is cleaned and dried, and a plasma processor is used to perform plasma bombardment treatment on the surface of the substrate.

In some embodiments of the present application, the flexible substrate includes, but is not limited to, polyurethane, polydimethylsiloxane (PDMS), rubber, copolyester (Ecoflex), polyethylene terephthalate ( PET), polyvinyl chloride (PVC), paper base, etc.

In some embodiments of the present application, the liquid flexible substrate material needs to use spin coating, slot coating method, electrospray process, electric field driven jet deposition micro-nano 3D printing technology; solid thermoplastic flexible substrate material can use electric field driven melting Prepared by jet micro-nano 3D printing technology, a flexible substrate is made on the substrate, and it is heated and cured.

In some embodiments of the present application, the substrate includes, but is not limited to, glass, plastic, and silicon wafers.

In some embodiments of the present application, the thickness of the flexible substrate is between 500 nm and 5 mm, and the area is between 0.1 cm ² and 1 cm ² .

In some embodiments of the present application, in the step (2), the master mold manufacturing method: according to the designed interdigital structure, the electric field-driven jet deposition micro-nano 3D printing technology is used to deposit the conductive material on the flexible substrate The interdigitated structure with high aspect ratio and high resolution is printed, and sintered and solidified at low temperature to form a master mold (conductive substrate).

In some embodiments of the present application, the conductive material includes but is not limited to flexible conductive silver paste, conductive ink, TPU and silver mixture, nano-silver conductive ink, nano-copper conductive ink, silver nanowire, graphene conductive ink or/or Flexible and highly conductive materials such as carbon nanotube conductive inks.

In some embodiments of the present application, the line width of the interdigitated structure of the conductive master mold is 500 nm-1 mm.

In some embodiments of the present application, the aspect ratio is as high as 6:1.

In some embodiments of the present application, the interdigital structure includes linear and curvilinear, preferably curvilinear, which can improve its tensile properties.

In some embodiments of the present application, the low-temperature sintering and curing is to volatilize the internal solvent to achieve better electrical conductivity. Different sintering conditions are selected for the conductive materials.

In some embodiments of the present application, in the step (3), the electrode material is prepared into a polymerization solution, and a layer of electrode material is deposited on the master mold through an electrochemical polymerization process, using a three-electrode system, and setting parameters.

In some embodiments of the present application, the electrode materials include, but are not limited to, polypyrrole (PPy), polyaniline (PANI), polythiophene (PTh) and derivatives thereof, such as poly-3,4-ethylenedioxy Thiophene (PEDOT), poly-3-4-fluorophenylthiophene (PFPT) and poly-3-methylthiophene (PMeT) and other high molecular conductive polymers.

In some embodiments of the present application, the electrochemical polymerization process includes potentiostatic method, galvanostatic method and cyclic voltammetry, and the growth rate and thickness of electrode material are controlled by adjusting deposition time, current density and deposition potential.

In some embodiments of the present application, in the three-electrode system, the saturated calomel electrode is the reference electrode, the platinum sheet is the counter electrode, and the master mold is the working electrode.

In some embodiments of the present application, in the step (4): preparing a suitable solid electrolyte according to the electrode material, coating the suitable solid electrolyte in the electrode material and the insulating gap, and standing for a period of time to cure.

In some embodiments of the present application, the solid electrolyte includes, but is not limited to, gel electrolytes such as H ₃ PO ₄ /PVA, H ₂ SO ₄ /PVA, KCl/PVA, LiCl/PVA, and LiClO ₄ /PVA.

In some embodiments of the present application, the insulating gap is the distance between adjacent electrodes, and by reducing the insulating gap, the time for ions to pass through can be reduced, and the electrochemical performance can be improved, and the width thereof is 0.001 mm-1 mm.

In some embodiments of the present application, in step (5), the same material as the flexible substrate is selected, and the same process as step (1) is used to uniformly coat a layer on the electrolyte and the flexible substrate, and the Once it is sealed, the fabrication of miniature flexible supercapacitors can be completed.

In some embodiments of the present application, a flexible micro-supercapacitor prepared by the above-mentioned manufacturing method is also provided, which can reach a surface capacitance of 27-1200 mF/cm ² and an energy density of 0.00000375 KW·h at a scan rate of 10 mV/s. /cm ² -0.000167KW.h/cm ² , the power density is 0.000135KW/cm ² -0.006012KW/cm ² .

Compared with the prior art, the beneficial effects of the present application are:

The present application combines the advantages of micro-nano 3D printing master molds and electrochemical polymerization to achieve high-efficiency and low-cost mass production of large-aspect-ratio, high-resolution flexible micro-supercapacitors.

Has the following significant advantages:

(1) The problem of high-resolution, high-aspect-ratio interdigital structure fabrication that cannot be achieved by existing processes such as etching is solved, and the efficient and low-cost mass fabrication of miniature flexible supercapacitors is realized.

(2) The patterning of the conductive polymer was successfully realized, the surface area was increased, the capacitance was increased, and the electrochemical performance of the supercapacitor was greatly improved.

(3) Using the electrochemical polymerization process, the thickness of the electrode material and the insulating gap can be controlled, thereby improving the electrochemical performance of the supercapacitor.

(4) The fabricated micro-supercapacitors have good mechanical properties and good electrochemical properties, and can be widely used in portable wireless communication systems, micro-electromechanical systems, biological wireless sensors, multifunctional micro/nano systems, micro-robots and wearable/implantable into medical equipment and other fields.

(5) The process is simple, the manufacturing cost is low, no expensive facilities are required, the process adaptability is strong, and the controllability is good.

(6) The materials that can be used are wide and the utilization rate is high, no ultra-quiet environment is required, and there is no pollution to the environment.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the drawings that are used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained from these drawings without creative effort.

1 is a schematic diagram of the process flow diagram of the present application for preparing flexible micro-supercapacitors;

2 is a schematic diagram of a linear interdigital electrode in Example 1 of the present application;

FIG. 3 is a schematic diagram of a curved interdigital electrode in Example 2 of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

Various fabrication techniques such as photolithography, plasma etching, laser scribing, and inkjet printing methods face many deficiencies and limitations in realizing flexible micro-supercapacitors based on conductive polymers, such as processing cost, fabrication cycle, interdigitated structure, Resolution, aspect ratio, etc. The fabrication method of the conductive polymer flexible micro-supercapacitor based on the micro-nano 3D printing master mold and electropolymerization proposed in this application successfully solves the above problems.

A micro-flexible substrate is fabricated on the substrate; the electric field-driven jet deposition micro-nano 3D printing technology is used to print a large aspect ratio and high-resolution interdigital structure on the micro-flexible substrate, which is used as a master mold (conductive substrate) ; Use electrochemical polymerization process to deposit the electrode material on the master mold; prepare a solid electrolyte and coat it on the electrode material and the insulating gap; seal it with a flexible base material to obtain high resolution, large height and width than the miniature flexible supercapacitors.

Example 1

The micro-flexible supercapacitors were fabricated by electric field-driven jet deposition micro-nano 3D printing technology and electrochemical polymerization process. PDMS was used as the micro-flexible substrate, conductive silver paste 201s (a flexible conductive silver paste) was used as the conductive substrate, and PPy was used as the electrode material. , the solid electrolyte is LiCl/PVA gel electrolyte, and the interdigital structure is selected as a straight interdigital structure, as shown in Figure 2. Its technological process is shown in Figure 1, and the specific preparation steps include:

(1) Fabrication of miniature flexible substrates

Ordinary glass was used as the substrate; the glass substrate was first cleaned, ultrasonically treated with deionized water for 10 min, and then dried with nitrogen. On the glass substrate, a micro-nano 3D printing technology was used for electric field-driven jet deposition to prepare a layer of PDMS film. An appropriate amount of Dow Corning 184 canned adhesive was selected, with a thickness of about 1 μm and an area of 0.3 cm ² . PDMS was prepared in a vacuum environment. For heating and curing, the heating temperature was set to 85° C. and the heating time was set to 20 min.

(2) Making a master mold

Design a linear interdigital structure program, import it into the printing equipment, select a glass nozzle with a diameter of 30μm, set the air pressure to 200KPa, the distance between the nozzle and the substrate is 50μm, the voltage is 850V, the nozzles for each layer are lifted by 15μm, the printing speed is 2mm/s, and an electric field is used. Driven jet deposition micro-nano 3D printing technology, the stretchable silver paste is printed on PDMS to print a large aspect ratio, high-resolution interdigital structure as a conductive substrate (master mold), placed in a drying oven, and the temperature is set to 150 ℃, sintered for 30min, taken out. The master mold line width is 10 μm, the insulation gap is 50 μm, and the aspect ratio is 6:1.

(3) Deposition electrode material

Preparation of polymerization solution: Dissolve 1 mmol of pyrrole, 1 mmol of p-toluenesulfonic acid and 1 mmol of dodecylbenzenesulfonic acid in 30 ml of distilled water, and ultrasonicate for 5 min to prepare a polymerized electrolyte;

Select an electrochemical workstation, adopt the potentiostatic polymerization method, and use a three-electrode system. The saturated calomel electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, and the master mold is used as the working electrode. The three electrodes are immersed in the solution, and the polymerization potential is set to 0.6V , the polymerization time was 2400 s, and a polypyrrole film was deposited on the master mold. The polypyrrole film was tightly attached to the conductive substrate, and its thickness was about 10 μm. electrode.

(4) Preparation of solid electrolyte

LiCl/PVA gel electrolyte was used as the solid electrolyte, 1.0g PVA powder was added to 1.0mol Li ^- LiCl aqueous solution, then heated to 85°C under vigorous stirring, until the solution became clear and transparent, and cooled to room temperature for later use; the prepared The gel electrolyte was evenly coated on the PPy film and the insulating gap, and allowed to stand for 12 h to cure.

(5) Package

Using 3D printing technology, a layer of PDMS is printed on the electrolyte and the micro flexible substrate to make it completely wrapped, and the PDMS is heated and cured in a vacuum environment. Miniature flexible supercapacitors are available.

Example 2

The micro-flexible supercapacitor was fabricated by electric field-driven jet deposition micro-nano 3D printing technology and electrochemical polymerization process. Ecoflex was used as the micro-flexible substrate, TPU and Ag mixture was used as the conductive material, PANI was used as the electrode material, and the solid electrolyte was H ₂ SO ₄ / PVA gel electrolyte, the interdigital structure adopts curved interdigital structure. The specific preparation steps include:

(1) Fabrication of miniature flexible substrates

Using silicon wafers as substrates: firstly, the silicon wafer substrates were cleaned, ultrasonically treated with deionized water for 10 minutes, and then blown dry with nitrogen. On the glass substrates, an electric field-driven jet deposition micro-nano 3D printing technology process was used to obtain a layer of Ecoflex film. Choose Smooth-on, Ecofiex00-30 platinum cured silica gel, A:B mass ratio of 1:1, its thickness is about 10μm, the area is 0.2cm ² , and the Ecoflex is heated and cured in a vacuum environment, and the heating temperature is set to 85 °C, and the heating time was set to 60 min.

(2) Making a master mold

Preparation of conductive material: Dissolve 3g TPU in 5mL DMF solution, add 10g silver flakes, add 3g carbon nanotubes in 3 times, and stir ultrasonically for 30 minutes to obtain a TPU and Ag mixture solution.

Design the curve interdigital structure program, import it into the printing equipment, select the stainless steel nozzle of model 30, the diameter is 120μm, the air pressure is set to 250KPa, the distance between the nozzle and the substrate is 200μm, the voltage is 880V, the nozzle is lifted by 100μm for each layer, and the printing speed is 2mm. /s, using the electric field-driven jet deposition micro-nano 3D printing technology, the TPU and silver mixtures were printed on the Ecoflex with a large aspect ratio, high-resolution interdigital structure, as a conductive substrate (master mold), placed in a drying box, Set the temperature to 80°C, sinter for 120min, and take out. The line width of the master mold is 100μm, the insulation gap is 100μm, the aspect ratio is 5:1, and the curvature of the curve is about 30°.

(3) Deposition electrode material

Preparation of polymerization solution: dissolving 0.1M aniline monomer in 0.5MH ₂ SO ₄ solution, and after sonicating for 5 min, a polymer electrolyte was prepared.

The master mold was heated in a HCl solution (30 ml H ₂ O + 70 ml HCl) at 40° C. for 20 minutes to perform hydrophilic treatment of the master mold. Then, rinse the master mold with secondary water until neutral, and dry it for later use.

Select an electrochemical workstation, adopt cyclic voltammetry, and use a three-electrode system. The saturated calomel electrode is used as the reference electrode, the platinum sheet is used as the counter electrode, and the master mold is used as the working electrode. The three electrodes are immersed in the solution, and the polymerization rate is set to 50mV/ s, the polymerization time was 400 s, polyaniline was deposited on the master mold, and the polyaniline film was tightly attached to the conductive substrate with a thickness of about 5 μm. After the polymerization was completed, the sample was vacuum-dried at 60 °C to obtain Ag/PANI flexible electrode.

(4) Preparation of solid electrolyte

The solid electrolyte is H ₂ SO ₄ /PVA gel electrolyte, 5g H ₂ SO ₄ , 5g PVA and 50mL are added to the flask, and stirred continuously at 90°C for 2 hours until a clear and transparent solution is formed to prepare PVA/H ₂ SO ₄ Solid electrolyte, cooled to room temperature for use. The prepared gel electrolyte was evenly coated on the PANI film and the insulating gap, and allowed to stand for 12 hours to cure.

(5) Package

Using 3D printing technology, a layer of Ecoflex is printed on the electrolyte and the micro flexible substrate to completely wrap it. The Ecoflex is heated and cured in a vacuum environment. The heating temperature is set to 80°C and the heating time is set to 120min. Flexible micro-supercapacitors are available.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or some technical features thereof are equivalently replaced; and these modifications or replacements do not drive the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims (19)

1. A manufacturing method of a flexible micro super capacitor is characterized by comprising the following steps: (1) manufacturing a flexible substrate on a substrate; (2) Printing an interdigital structure female die by adopting an electric field driven jet deposition micro-nano 3D printing technology, namely printing an interdigital structure with a large height-width ratio and high resolution on a flexible substrate by adopting the electric field driven jet deposition micro-nano 3D printing technology according to the designed interdigital structure, and sintering and curing to form the female die; (3) Depositing an electrode material on the master die through an electrochemical polymerization process; (4) uniformly coating the solid electrolyte on the electrode material; (5) And sealing and manufacturing the flexible micro super capacitor.

2. The method of claim 1, wherein the flexible substrate comprises Polydimethylsiloxane (PDMS), rubber, copolyester (Ecoflex), polyethylene terephthalate (PET), polyvinyl chloride (PVC), paper base.

3. The method according to claim 1, wherein in the step (2), the line width of the master mold of the interdigital structure is 500nm to 1mm, and the aspect ratio is up to 6: 1.

4. The method of claim 1, wherein the conductive material comprises a flexible conductive silver paste, a conductive ink, a TPU and silver mixture, a nano silver conductive ink, a nano copper conductive ink, a silver nanowire, a graphene conductive ink, or/and a carbon nanotube conductive ink.

5. The method as claimed in claim 1, wherein the sintering and curing process is a low temperature sintering and curing process, which volatilizes the internal solvent to achieve better electrical conductivity, the sintering temperature is between 80 ℃ and 150 ℃, the sintering time is between 30min and 120min, and different sintering conditions are selected according to different conductive materials.

6. The method according to claim 1, wherein in the step (3), the electrode material is prepared into a polymerization solution, and a layer of the electrode material is deposited on the master model by setting parameters through an electrochemical polymerization process by using a three-electrode system.

7. The method of claim 1, wherein the electrode material includes but is not limited to polypyrrole, polyaniline, polythiophene and their derivatives.

8. The method for manufacturing a flexible micro supercapacitor according to claim 1, wherein in the step (4): preparing a suitable solid electrolyte according to the electrode material, coating the suitable solid electrolyte in the electrode material and the insulating gap, and standing for curing.

9. The method for manufacturing a flexible micro supercapacitor according to claim 1, wherein in the step (5): and (3) selecting the same material as the flexible substrate, uniformly coating a layer above the electrolyte and the flexible substrate by adopting the same process as the step (1), and sealing the electrolyte and the flexible substrate to finish the manufacturing of the miniature flexible super capacitor.

10. The manufacturing method of the flexible micro supercapacitor according to claim 1, wherein a liquid flexible substrate material needs to adopt spin coating, a slit coating method, an electrospray process, an electric field driven jet deposition micro-nano 3D printing technology; the solid thermoplastic flexible substrate material can be prepared by adopting an electric field driven melting jet micro-nano 3D printing technology, a flexible substrate is manufactured on a base plate, and the flexible substrate is heated and solidified.

11. The method as claimed in claim 1, wherein the flexible substrate has a thickness of 500nm-5mm and an area of 0.1cm ² -1cm ² 。

12. The method of claim 3, wherein the interdigitated structure comprises straight and curved lines.

13. The method of claim 12 wherein said interdigitated structure is curved to enhance its tensile properties.

14. The method as claimed in claim 6, wherein the electrochemical polymerization process comprises potentiostatic method, galvanostatic method and cyclic voltammetry, and the growth rate and thickness of the electrode material are controlled by adjusting deposition time, current density and deposition potential.

15. The method according to claim 14, wherein in the three-electrode system, the saturated calomel electrode is a reference electrode, the platinum sheet is a counter electrode, and the master model is a working electrode.

16. The method as claimed in claim 7, wherein the electrode material is poly (3, 4-ethylenedioxythiophene), poly (3-4-fluorophenylthiophene) or poly (3-methylthiophene) polymer.

17. The method of claim 8 wherein the solid electrolyte includes but is not limited to H ₃ PO ₄ /PVA、H ₂ SO ₄ PVA, KCl/PVA, liCl/PVA and LiClO ₄ PVA gel electrolyte.

18. The method as claimed in claim 8, wherein the insulation gap is a distance between adjacent electrodes, and the insulation gap is reduced to reduce ion passage time and improve electrochemical performance, and has a width of 0.001mm to 1mm.

19. The flexible micro-supercapacitor prepared by the method for manufacturing the flexible micro-supercapacitor according to any one of claims 1 to 17, wherein the surface capacitance of the flexible micro-supercapacitor can reach 27-1200mF/cm at a scanning rate of 10mV/s ² The energy density is 0.00000375 KW.h/cm ² -0.000167KW·h/cm ² The power density is 0.000135KW/cm ² -0.006012KW/cm ² 。

Images