Three-dimensional self-curling miniature supercapacitor and controllable preparation method thereof

Abstract

The invention belongs to the technical field of three-dimensional micro-nano manufacturing and energy storage, and discloses a three-dimensional self-curling micro supercapacitor and a controllable preparation method thereof.The method comprises the steps that a double-layer film substrate is prepared, the double-layer film substrate comprises a conductive function layer with the negative thermal expansion coefficient on the top layer and a magnetic film substrate with the positive thermal expansion coefficient on the bottom layer, a high remanence material and a magnetocaloric material are uniformly distributed in the magnetic film substrate; preparing a patterned interdigital electrode on the surface of the conductive functional layer; preparing a positive electrode on one side of the interdigital electrode and preparing a negative electrode on the other side of the interdigital electrode on the surface of the conductive functional layer to obtain the composite planar micro supercapacitor. Bending and deforming the composite planar micro supercapacitor in a magnetic field to obtain a self-curling structure; and adding a liquid crystal electrolyte into the self-curling structure to obtain the three-dimensional self-curling micro supercapacitor. The projection area of the device is further reduced, the space utilization rate of the device is improved, and the energy density of the device in unit area is further improved.

Description

Technical Field

[0001] The present invention belongs to the field of three-dimensional micro-nano manufacturing and energy storage technology, and specifically relates to a three-dimensional self-curling micro supercapacitor and a controllable preparation method thereof. Background Art

[0002] Compared with lithium-ion batteries, interdigital micro-supercapacitors benefit from physically isolated electrode structures, do not require the introduction of diaphragms, and will not cause obvious abnormal safety accidents in collision and high temperature environments. They have the characteristics of high safety, high power density, long service life, environmental friendliness and easy integration. However, interdigital micro-supercapacitors urgently need to break through the technical bottleneck of low energy density. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a three-dimensional self-curling micro supercapacitor and a controllable preparation method thereof. The present invention further reduces the projected area of ​​the device, improves the space utilization of the device, and thus improves the energy density per unit area of ​​the device.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows: A controllable preparation method of a three-dimensional self-curling micro supercapacitor includes the following process: A double-layer thin film substrate is prepared, wherein the double-layer thin film substrate comprises a conductive functional layer with a negative thermal expansion coefficient on the top layer and a magnetic thin film substrate with a positive thermal expansion coefficient on the bottom layer, wherein the conductive functional layer is arranged on the surface of the magnetic thin film substrate, and a high remanence material and a magnetocaloric material are uniformly distributed in the magnetic thin film substrate; A patterned interdigital electrode is prepared on the surface of the conductive functional layer; On the surface of the conductive functional layer, a positive electrode is prepared on one side of the interdigital electrode, and a negative electrode is prepared on the other side of the interdigital electrode to obtain a composite planar micro supercapacitor; The composite planar micro-supercapacitor is bent and deformed in a magnetic field to obtain a self-curling structure; A liquid crystal electrolyte is added to the self-curling structure to obtain the three-dimensional self-curling micro supercapacitor.

[0005] Preferably, the conductive functional layer is made of a graphene film, a carbon nanotube film or a graphene and carbon nanotube mixture film.

[0006] Preferably, patterned interdigital electrodes are prepared on the surface of the conductive functional layer by laser processing.

[0007] Preferably, the magnetic film substrate is made of a polydimethylsiloxane film doped with the high remanence material and the magnetocaloric material.

[0008] Preferably, the high remanence material is made of neodymium iron boron particles, and the magnetocaloric material is made of ferroferric oxide particles.

[0009] Preferably, the preparation process of the magnetic thin film substrate includes: The NdFeB particles, Fe3O4 particles and polydimethylsiloxane solution are mixed to obtain a magnetic solution, a curing agent is added to the magnetic solution, and the magnetic solution is evenly spin-coated on the surface of a silicon wafer by spin coating, and then cured to obtain the magnetic film substrate; The mixing ratio of the NdFeB particles, FeO particles and polydimethylsiloxane solution is (5-50) g: (5-50) g: 100 ml; The curing agent is hydrogen-containing silicone oil, and 1-10 ml of hydrogen-containing silicone oil is added to the magnetic solution.

[0010] Preferably, the negative electrode of the positive electrode is prepared by electrochemical deposition.

[0011] Preferably, when the composite planar micro-supercapacitor is bent and deformed in a magnetic field: By adjusting the process parameters of the electromagnetism process, the curling direction, speed, number of turns and configuration of the composite planar micro-supercapacitor are controlled; The process parameters of the electromagnetism process include: the frequency, amplitude and direction of the alternating current, the structure, number of turns, material and winding method of the coil.

[0012] Preferably, the liquid crystal electrolyte is an electrolyte prepared by mixing liquid crystal lauryl ether and phosphoric acid in a mass ratio of 1:(5-20), and the liquid crystal electrolyte is placed in the self-curling structure by drop coating.

[0013] The present invention also provides a three-dimensional self-curling micro supercapacitor, which is prepared by the controllable preparation method of the three-dimensional self-curling micro supercapacitor as described above.

[0014] Compared with the prior art, the present invention has at least the following beneficial technical effects: In the controllable preparation method of the three-dimensional self-curling micro-supercapacitor of the present invention, the self-curling method used does not need to introduce a sacrificial layer and a selective etching process, simplifies the preparation process, improves operational safety, and saves reaction time; in addition, unlike the existing magnetic force driving method, the high remanence material and the magnetocaloric material are evenly distributed in the conductive functional layer of the present invention, so the present invention introduces the driving force through the high-frequency electromagnetocaloric effect, and at the same time, based on the low-frequency electromagnetic effect, the magnitude and direction of the electromagnetic force are flexibly regulated to achieve further driving and precise control of the curling deformation, which is expected to solve the problems of insufficient driving force and poor controllability of the prior art, and improve process repeatability and stability. Compared with the commonly used liquid aqueous electrolytes and solid / quasi-solid gel electrolytes, the present invention adopts a liquid crystal electrolyte, which retains a relatively ordered mesoporous structure while retaining good fluidity and continuity, providing a favorable diffusion power and transport channel for electrolyte ions, effectively alleviating the problems of high freezing point of liquid aqueous electrolytes and slow diffusion of solid / quasi-solid electrolyte ions, and is more conducive to improving the electrochemical energy storage performance of energy storage devices. It can be seen from the above scheme that the present invention further reduces the projection area of ​​the device, thereby improving the space utilization rate of the device and thus increasing the energy density per unit area of ​​the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a controllable preparation process of a three-dimensional self-curling micro-supercapacitor provided in an embodiment of the present invention; Figure 2 A schematic diagram of the processing flow of a three-dimensional self-curling micro-supercapacitor provided in an embodiment of the present invention; In the figure: 1-functional layer negative thermal expansion coefficient material, 2-bottom layer positive thermal expansion coefficient material, 3-high remanence material, 4-magnetocaloric material, 5-high frequency electromagnetic thermal stress, 6-low frequency electromagnetic force, 7-self-curling configuration of different characteristic sizes, 8-laser, 9-interdigitated electrodes, 10-positive electrode, 11-negative electrode, 12-planar micro supercapacitor, 13-three-dimensional self-curling micro supercapacitor, 14-liquid crystal electrolyte. DETAILED DESCRIPTION

[0016] Hereinafter, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without violating the principles of the present application, the features in the various embodiments can be combined to obtain new implementations, or certain features in certain embodiments can be replaced to obtain other preferred implementations.

[0017] In response to the problem of low energy density of micro supercapacitors, the present invention proposes an efficient three-dimensional strategy for the overall structure of the device - a new dual-mode electromagnetic drive-control integrated strong drive, high precision, and controllable self-curling technology, studies the controllable preparation mechanism of three-dimensional self-curling micro supercapacitors, and solves the problems of "increasing electrode height" with limited increase in height resulting in poor energy density improvement effect, and easy cracking and collapse of electrodes resulting in poor device stability. A three-dimensional self-curling micro supercapacitor with high space utilization and high energy density is developed to further broaden its application scenarios.

[0018] Reference Figure 1 The controllable preparation method of the three-dimensional self-curling micro supercapacitor of the present invention comprises the following process: Preparation of double-layer thin film substrates, see Figure 1 The double-layer film substrate comprises a conductive functional layer with a negative thermal expansion coefficient on the top layer and a magnetic film substrate with a positive thermal expansion coefficient on the bottom layer, wherein the conductive functional layer is arranged on the surface of the magnetic film substrate, and the high remanence material and the magnetocaloric material are evenly distributed in the magnetic film substrate; the double-layer film substrate of the present invention is driven and precisely controlled to self-curl and deform under the action of high-frequency "electromagnetocaloric" thermal stress and low-frequency "electromagnetic force", so the double-layer film substrate of the present invention has a self-curling function; A patterned interdigital electrode 9 is prepared on the surface of the conductive functional layer, and the interdigital electrode 9 also serves as a current collector and a conductive electrode; See also Figure 2 On the surface of the conductive functional layer, a positive electrode 10 is prepared on one side of the interdigital electrode 9, and a negative electrode 11 is prepared on the other side of the interdigital electrode 9 to obtain a composite planar micro supercapacitor; The composite planar micro-supercapacitor is bent and deformed in a magnetic field to obtain a self-curling structure; A liquid crystal electrolyte 14 is added to the self-curling structure to obtain the three-dimensional self-curling micro supercapacitor of the present invention.

[0019] In the above scheme of the present invention, the conductive functional layer can be a graphene film, a carbon nanotube film or a graphene and carbon nanotube mixture film. For such conductive functional layer, a laser processing method can be used to prepare patterned interdigitated electrodes 9 on the surface of the conductive functional layer. Specifically, by controlling the processing power and scanning rate of the laser processing, the conductive functional layer can be induced.

[0020] In the above solution of the present invention, the magnetic film substrate can be made of polydimethylsiloxane film doped with the high remanence material and magnetocaloric material. Specifically, the high remanence material can be made of neodymium iron boron particles, and the magnetocaloric material can be made of ferroferric oxide particles.

[0021] The preparation process of the magnetic thin film substrate of the present invention comprises: NdFeB particles, FeO particles and polydimethylsiloxane solution are mixed to obtain a magnetic solution, a curing agent is added to the magnetic solution, and the magnetic solution is evenly spin-coated on the surface of a silicon wafer by spin coating, and then cured to obtain the magnetic film substrate. The mixing ratio of the NdFeB particles, FeO particles and polydimethylsiloxane solution is (5-50) g: (5-50) g: 100 ml; The curing agent is hydrogen-containing silicone oil, and 1 to 10 ml of the curing agent hydrogen-containing silicone oil is added to the magnetic solution.

[0022] Typically, the negative electrode 11 of the positive electrode 10 can be prepared by electrochemical deposition, wherein the negative electrode 11 of the positive electrode 10 can be made of porous positive / negative electrode materials with high specific surface area, such as transition metal oxides, overplated metal phosphides, and conductive polymers.

[0023] In the above invention, when the composite planar micro supercapacitor is bent and deformed in a magnetic field: By adjusting the process parameters of the electromagnetism process, the curling direction, speed, number of turns and configuration of the composite planar micro-supercapacitor are controlled; wherein the electromagnetism uses a dual-mode high and low frequency electromagnetism, which is generated by a three-dimensional Helmholtz coil; The process parameters of the electromagnetism process include: the frequency, amplitude and direction of the alternating current, the structure, number of turns, material and winding method of the coil.

[0024] The acquisition of the above parameters requires the design of multiple sets of experiments, and the final optimized parameters are obtained through continuous parameter debugging.

[0025] In the above invention, the liquid crystal electrolyte is a mixture of liquid crystal lauryl ether and phosphoric acid in a mass ratio of 1: (5-20), and the liquid crystal electrolyte is placed in the self-curling structure by drip coating. The electrochemical performance of the coiled tube micro-supercapacitor can be optimized by adjusting the lauryl ether / phosphoric acid ratio.

[0026] The principle of the above technical solution of the present invention is as follows: In order to realize the controllable preparation of three-dimensional self-curling micro-supercapacitors, the present invention adopts a new dual-mode electromagnetic drive-control integrated strong drive, high precision, controllable self-curling scheme, and the preparation of a double-layer magnetic film (i.e., a double-layer film substrate) is the key. Among them, the double-layer magnetic film includes an upper functional layer of negative thermal expansion coefficient material 1 and a bottom layer of positive thermal expansion coefficient material 2 added with high remanence material 3 and magnetocaloric material 4. In order to introduce thermal stress into the double-layer magnetic film, the present invention adopts electromagnetic heating, and the magnetocaloric material such as ferroferric oxide (Fe3 O 4 ) will produce very high hysteresis loss under the action of high-frequency electromagnetism, which will cause temperature change and form high-frequency electromagnetic thermal stress 5 in the double-layer magnetic film, driving the double-layer magnetic film to bend and deform; at the same time, the bottom high remanent magnetic material neodymium iron boron (NdFeB) particles are further driven and precisely controlled by the low-frequency electromagnetism. By adjusting the process parameters of the electromagnetism process (such as alternating current frequency / amplitude / direction, coil structure / number of turns / material / winding method), the controllable preparation of self-curling configurations 7 with different characteristic sizes can be achieved.

[0027] In order to prepare the interdigitated electrodes 9, the laser 8 is applied to the surface of the functional layer negative thermal expansion coefficient material 1 to realize the in-situ preparation of the patterned electrodes; in order to prepare a high-performance composite micro-supercapacitor, the electrode materials corresponding to the positive electrode 10 and the negative electrode 11 are further deposited in situ on both sides of the interdigitated electrodes 9 by electrochemical deposition to form a planar micro-supercapacitor 12. Driven by the aforementioned self-curling scheme, the preparation of the three-dimensional self-curling micro-supercapacitor 13 is realized, and the liquid crystal lauryl ether / phosphoric acid electrolyte 14 is further dripped into the three-dimensional self-curling micro-supercapacitor 13 by drop coating for subsequent electrochemical performance testing.

[0028] Example This embodiment provides a typical controllable preparation method of the three-dimensional self-curling micro supercapacitor of the present invention, which specifically includes the following steps: Step 1: Prepare magnetic film precursor solution: NdFeB particles, Fe 3 O 4 ) The particles and the PDMS solution were mixed and stirred in a ratio of 8 g: 8 g: 20 ml, and then 2 ml of curing agent hydrogenated silicone oil was added, and the solution was evenly spin-coated on the surface of a clean silicon wafer by spin coating, and then cured at 100 ° C for two hours to successfully prepare the magnetic film substrate, and the thickness of the magnetic film substrate was 160 μm; Step 2, preparing a graphene solution with a concentration of 1 mg / ml, and spin coating it on the surface of the magnetic film substrate obtained in step 1, followed by drying to form a conductive functional layer on the surface of the magnetic film substrate to obtain a double-layer film substrate, the thickness of the double-layer film substrate is 180 microns; Step 3: The double-layer film substrate in step 2 is peeled off from the surface of the silicon wafer and cut into strip films. A patterned interdigital electrode is manufactured on the surface of the strip film by laser processing. The processing power (13.5 W) and the scanning rate (10 cm s -1 ), applying laser to the surface of the top functional layer (i.e., the conductive functional layer) in step 2 to achieve in-situ preparation of the patterned graphene interdigitated electrodes 9; Step 4: depositing a layer of polyaniline conductive polymer as a positive electrode material on the electrode surface of one side of the interdigital electrode 9 in step 3 by electrochemical deposition, and depositing a layer of redox graphene as a negative electrode material on the electrode on the other side of the interdigital electrode 9 to prepare a composite planar micro supercapacitor; Step 5: construct a three-dimensional uniform magnetic field coil, build a controllable uniform magnetic field platform, use an AC / DC current source to input alternating current, and in-situ control the strength and direction of the electromagnetism; Step 6: Place the composite planar micro-supercapacitor obtained in step 4 in the controllable uniform magnetic field (50 μT) in step 5, and the magnetocaloric material of the bottom magnetic film substrate, ferroferric oxide (Fe 3 O 4 ) particles will produce high hysteresis loss under the action of high-frequency electromagnetism, which will cause temperature change, form thermal stress difference in the double-layer film substrate, and drive the film to bend and deform; at the same time, the bottom high remanence material neodymium iron boron (NdFeB) particles will further drive and accurately control the curling process under the action of low-frequency electromagnetism, and finally obtain a self-curling structure; Step 7: mix lauryl ether and phosphoric acid in a mass ratio of 1:8 to prepare an electrolyte, thereby preparing a liquid crystal electrolyte, and place it in the self-curling structure obtained in step 6 by drop coating to achieve controllable preparation of a three-dimensional self-curling composite micro-supercapacitor.

[0029] After testing, the main technical indicators of the three-dimensional self-curling micro supercapacitor obtained in this embodiment are as follows: Electrochemical energy storage performance: The device projected area is reduced by 3 times, the capacitance and energy density are increased by 3 times, the electrochemical impedance is ≤100 Ω, and the energy storage area capacitance is 12.9 mF cm -2 , areal energy density 14.7 μWh cm -2 The successful development of the above-mentioned new self-curling manufacturing method and the new low-temperature resistant liquid crystal electrolyte provided by the present invention can provide an effective strategy for the development of micro supercapacitors with high space utilization and high energy density, promote the further improvement of the performance of micro energy storage devices, and is of great significance to accelerating the country's "carbon peak and carbon neutrality" process.

[0030] The above is only one embodiment of the present invention, not all or the only embodiment. Any equivalent changes made by ordinary technicians in this field in the face of the technical solution of the present invention after reading the specification of the present invention are covered by the claims of the present invention.

Claims

1. A controllable preparation method of a three-dimensional self-curling micro supercapacitor, characterized in that: The process includes the following: A double-layer thin film substrate is prepared, wherein the double-layer thin film substrate comprises a conductive functional layer with a negative thermal expansion coefficient on the top layer and a magnetic thin film substrate with a positive thermal expansion coefficient on the bottom layer, wherein the conductive functional layer is arranged on the surface of the magnetic thin film substrate, and a high remanence material and a magnetocaloric material are uniformly distributed in the magnetic thin film substrate; A patterned interdigital electrode (9) is prepared on the surface of the conductive functional layer; On the surface of the conductive functional layer, a positive electrode (10) is prepared on one side of the interdigital electrode (9), and a negative electrode (11) is prepared on the other side of the interdigital electrode (9), so as to obtain a composite planar micro-supercapacitor; The composite planar micro-supercapacitor is bent and deformed in a magnetic field to obtain a self-curling structure; A liquid crystal electrolyte is added to the self-curling structure to obtain the three-dimensional self-curling micro supercapacitor.

2. The controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 1, characterized in that: The conductive functional layer is made of a graphene film, a carbon nanotube film or a graphene and carbon nanotube mixture film.

3. The controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 2, characterized in that: Patterned interdigital electrodes (9) are prepared on the surface of the conductive functional layer by laser processing.

4. The controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 1, characterized in that: The magnetic film substrate is a polydimethylsiloxane film doped with the high remanence material and the magnetocaloric material.

5. A controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 1 or 4, characterized in that: The high remanence material is made of neodymium iron boron particles, and the magnetocaloric material is made of ferroferric oxide particles.

6. The controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 5, characterized in that: The preparation process of the magnetic thin film substrate comprises: The NdFeB particles, Fe3O4 particles and polydimethylsiloxane solution are mixed to obtain a magnetic solution, a curing agent is added to the magnetic solution, and the magnetic solution is evenly spin-coated on the surface of a silicon wafer by spin coating, and then cured to obtain the magnetic film substrate; The mixing ratio of the NdFeB particles, FeO particles and polydimethylsiloxane solution is (5-50) g: (5-50) g: 100 ml; The curing agent is hydrogen-containing silicone oil, and 1-10 ml of hydrogen-containing silicone oil is added to the magnetic solution.

7. The controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 1, characterized in that: The negative electrode (11) of the positive electrode (10) is prepared by an electrochemical deposition method.

8. The controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 1, characterized in that: When the composite planar micro-supercapacitor is bent and deformed in a magnetic field: By adjusting the process parameters of the electromagnetism process, the curling direction, speed, number of turns and configuration of the composite planar micro-supercapacitor are controlled; The process parameters of the electromagnetism process include: the frequency, amplitude and direction of the alternating current, the structure, number of turns, material and winding method of the coil.

9. The controllable preparation method of a three-dimensional self-rolled micro supercapacitor according to claim 1, characterized in that: The liquid crystal electrolyte is an electrolyte mixed with liquid crystal lauryl ether and phosphoric acid in a mass ratio of 1: (5-20), and the liquid crystal electrolyte is placed in the self-curling structure by drop coating.

10. A three-dimensional self-rolling micro supercapacitor, characterized in that: The three-dimensional self-rolling micro supercapacitor is prepared by the controllable preparation method of the three-dimensional self-rolling micro supercapacitor according to any one of claims 1 to 9.

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