High-temperature-resistant miniature supercapacitor based on porous GaN and preparation method thereof

Abstract

The invention provides a high-temperature-resistant miniature supercapacitor based on porous GaN and a preparation method of the high-temperature-resistant miniature supercapacitor. The method comprises the steps that the porous GaN grows on the upper surface of a pretreated insulating substrate; a patterned current collector-porous GaN-sapphire structure is obtained; obtaining a main body structure of the miniature supercapacitor; and packaging the porous GaN substrate to complete the preparation of the high-temperature-resistant micro supercapacitor based on the porous GaN. According to the method, the porous GaN is formed by performing electrochemical etching on the GaN thin film deposited on the pretreated insulating substrate, so that the defect that the uniformity of holes of the porous GaN obtained by a method of corroding and grinding a GaN single crystal wafer and then coating a current collector with the ground slurry in the prior art is relatively poor is overcome; the high temperature resistance of the super capacitor is effectively improved, and meanwhile, the micro super capacitor with a finer structure is formed by utilizing the photoetching technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-nano devices, and in particular relates to a method for preparing a micro supercapacitor, which can be used for electronic equipment in high temperature environments. Background Art

[0002] A capacitor is a basic electronic component whose main function is to store electrical energy and release it when needed. It consists of two electrodes that are insulated from each other and separated by a layer of dielectric material. When voltage is applied across the capacitor, charges gather on the surface of the electrodes to form an electric field and store energy. Supercapacitors are an energy storage device between capacitors and batteries. Although they perform well in terms of power density and cycle life, more and more application scenarios require operation in extreme high temperature environments and micro-nano sizes, such as electric vehicles, oil exploration, aerospace, high-temperature furnaces and other fields. These fields have extremely high performance requirements for supercapacitors, especially stability in high temperature environments. Therefore, high-temperature resistant micro supercapacitors have become the key to improving the performance of equipment in these fields.

[0003] The basic structure of high temperature resistant micro supercapacitor is as follows Figure 3 As shown, it includes a current collector, an electrode material and an insulating substrate stacked from top to bottom, wherein the current collector is any one or more of Ti / Al / Ni / Au, and the insulating substrate is sapphire. The electrode material is porous GaN formed by electrochemical etching, wherein the good pore uniformity of porous GaN will enhance its structural stability and chemical bonding strength, thereby improving its high temperature resistance.

[0004] In order to improve the high temperature resistance of supercapacitors, for example, the patent document with application publication number CN116230413A and titled "A gallium nitride / metal oxide composite electrode material and preparation method and application" discloses a porous GaN preparation method that can solve the high temperature resistance of supercapacitors. Its implementation scheme is: by corroding GaN single crystal wafers, a porous GaN single crystal film is obtained; and the single crystal film is immersed in a metal salt aqueous solution to obtain a gallium nitride / metal oxide composite electrode material through a hydrothermal reaction; the electrode material is mixed with a conductive agent and a binder and ground, N-methylpyrrolidone is added to obtain a slurry, and the slurry is coated on the current collector to obtain a working electrode for assembling a supercapacitor. This method has the following shortcomings: it obtains a porous GaN single crystal film by corroding a GaN single crystal wafer, and forms a slurry through the porous GaN single crystal through steps such as grinding, and then applies the slurry to a current collector to form an electrode, resulting in poor uniformity of the pores in the final electrode material, which weakens the high temperature resistance of the porous GaN. At the same time, the prepared supercapacitor is too large to be applied to micro-nano devices. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and to propose a method for preparing a high-temperature resistant micro supercapacitor based on porous GaN, so as to solve the technical problems of poor high-temperature resistance and oversized size of supercapacitors in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a high temperature resistant micro supercapacitor based on porous GaN comprises the following steps:

[0008] (1) Pre-treating the insulating substrate;

[0009] (2) Growing porous GaN on the upper surface of an insulating substrate:

[0010] Depositing a GaN film on a pre-treated sapphire insulating substrate, etching the deposited GaN-sapphire structure, and then performing pattern photolithography on the etched porous GaN-sapphire structure to obtain a patterned photoresist-porous GaN-sapphire structure with a photoresist pattern of interdigitated lines;

[0011] (3) Obtaining a patterned current collector-porous GaN-sapphire structure:

[0012] Depositing any one or more of Ti / Al / Ni / Au on the side of the patterned photoresist-porous GaN-sapphire structure facing the porous GaN and the patterned photoresist, and stripping the photoresist from the current collector / photoresist-porous GaN-sapphire structure formed by the deposition to obtain a patterned current collector-porous GaN-sapphire structure with interdigitated lines as the current collector pattern;

[0013] (4) Obtaining the main structure of the micro supercapacitor:

[0014] The obtained patterned current collector-porous GaN-sapphire structure with interdigitated lines is subjected to protective photolithography, and the photoresist-current collector-porous GaN-sapphire structure formed by the protective photolithography is subjected to inductively coupled plasma ICP etching, and then the photoresist-current collector-patterned porous GaN-sapphire structure after ICP etching is stripped and annealed to obtain a micro supercapacitor main structure;

[0015] (5) Encapsulating the main structure of the micro supercapacitor:

[0016] The positive and negative electrode leads are respectively led out from the porous GaN on the two sides of the main structure of the micro supercapacitor, and the polydimethylsiloxane film PDMS is encapsulated on one side of the current collector in the main structure of the micro supercapacitor where the positive and negative electrode leads are led out, completing the preparation of the high-temperature resistant micro supercapacitor based on porous GaN.

[0017] A micro high-temperature resistant supercapacitor based on porous GaN comprises a current collector, an electrode material and an insulating substrate which are stacked in sequence from top to bottom; the electrode material is porous GaN.

[0018] As an optimization, the current collector is made of any one or more of Ti / Al / Ni / Au.

[0019] As an optimization, the insulating substrate is made of sapphire.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) The present invention forms porous GaN by etching a GaN film deposited on a pre-treated insulating substrate, thereby avoiding the defect of poor pore uniformity of porous GaN obtained by the prior art method of corroding a GaN single crystal wafer, grinding the corroded porous GaN single crystal film, and then coating the ground slurry on a current collector to form an electrode. Compared with the prior art, the high temperature resistance of the supercapacitor is effectively improved.

[0022] 2) The present invention utilizes photolithography technology to form a micro-supercapacitor with a finer structure, which can be more easily integrated with other electronic components and applied to micro-nano devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flowchart of the method for preparing a high temperature resistant micro supercapacitor.

[0024] Figure 2 This is a schematic diagram of the implementation principle of the method for preparing a high-temperature resistant micro-supercapacitor of the present invention.

[0025] Figure 3 It is a schematic diagram of the structure of an existing high-temperature resistant micro supercapacitor. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific examples, but the present invention is not limited thereto. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0027] Embodiment 1:

[0028] Reference Figure 1 and2 , a method for preparing a high temperature resistant micro supercapacitor based on porous GaN, comprising the following steps:

[0029] Step 1) pre-treating the insulating substrate;

[0030] Deionized water, analytical grade acetone and isopropanol were used to ultrasonically clean the insulating substrate made of sapphire for 1.5 minutes respectively, and the cleaned insulating substrate was blown dry by nitrogen to achieve pretreatment.

[0031] Step 2) growing porous GaN on the upper surface of the insulating substrate:

[0032] 2a) placing a pre-treated insulating substrate made of sapphire into an MOCVD reaction chamber, and introducing NH3 with a flow rate of 3000sccm, H2 with a flow rate of 1200sccm, TMGa with a flow rate of 150sccm, and Cp2Mg with a flow rate of 100sccm under the conditions of a reaction chamber temperature of 1000°C and a pressure of 20Torr, wherein Cp2Mg is used as a p-type doping source, and a p-type GaN layer with a thickness of 200nm is grown to form a GaN-sapphire structure;

[0033] 2b) using an etching voltage of 20 V and using the GaN-sapphire structure and metal Pt as a working electrode and a counter electrode respectively, the GaN-sapphire structure is electrochemically etched for 20 min using a 0.4 M oxalic acid solution to obtain a porous GaN-sapphire structure, wherein the porous GaN in the porous GaN-sapphire structure has good pore uniformity;

[0034] 2c) For the porous GaN side of the porous GaN-sapphire structure, photoresist is drop-coated, and the photoresist is firstly spin-coated on a spinner at a low speed of 800 r / s for 5 seconds, and then spin-coated at a high speed of 3000 r / s for 30 seconds to complete uniform coating, and then the uniformly coated photoresist-porous GaN-sapphire structure is placed on a hot plate and pre-baked at a temperature of 120° C. for 90 seconds, wherein the photoresist in the photoresist-porous GaN-sapphire structure completely covers the porous GaN surface;

[0035] 2d) The pre-baked photoresist-porous GaN-sapphire structure was irradiated with 230 MJ / cm 2 The photoresist-porous GaN-sapphire structure is exposed with an exposure dose, and then the exposed photoresist-porous GaN-sapphire structure is immersed in a developer and deionized water for 30 seconds respectively and blown dry with nitrogen to obtain a patterned photoresist-porous GaN-sapphire structure with a pattern type of interdigitated lines and a line width of 2 to 50 μm. The patterned photoresist in the patterned photoresist-porous GaN-sapphire structure is formed by photoresist spaced by interdigitated lines.

[0036] Step 3) Obtaining a patterned current collector-porous GaN-sapphire structure:

[0037] 3a) Place the patterned photoresist-porous GaN-sapphire structure into the electron beam evaporation equipment and keep the equipment vacuum degree ≤1*10 -8 Torr, on the side of the patterned photoresist-porous GaN-sapphire structure facing the porous GaN and patterned photoresist A layer of current collector Ti / Au with a thickness of 20 nm / 50 nm is deposited at a deposition rate to obtain a current collector / photoresist-porous GaN-sapphire structure, wherein the current collector is located on the porous GaN surface between the patterned photoresist spacers;

[0038] 3b) The current collector / photoresist-porous GaN-sapphire structure is placed in an acetone solution and gently shaken with tweezers to peel off the interdigitated line-shaped photoresist and the deposited layer on its surface, and the body with the deposited layer pattern of interdigitated lines after the photoresist is peeled off is immersed in alcohol and deionized water respectively for 1 min for cleaning and then blown dry with nitrogen to obtain a patterned current collector-porous GaN-sapphire structure with the current collector pattern of interdigitated lines, wherein the patterned current collector is formed by the current collector spaced by the interdigitated lines.

[0039] Step 4) Obtaining the main structure of the micro supercapacitor:

[0040] 4a) drop-coating photoresist on the porous GaN and one side of the current collector in the patterned current collector-porous GaN-sapphire structure in which the current collector pattern is interdigitated lines, and then spin-coating on a spinner at a low speed of 800 r / s for 5 seconds, and then spin-coating at a high speed of 3000 r / s for 30 seconds, and placing on a hot plate for pre-baking at a temperature of 120° C. for 90 seconds to obtain a photoresist-current collector-porous GaN-sapphire structure in which both the photoresist pattern and the current collector pattern are interdigitated lines and the two patterns are arranged alternately, wherein the photoresist and the current collector are interdigitated lines arranged alternately;

[0041] 4b) The pre-baked photoresist-current collector-porous GaN-sapphire structure was subjected to a photolithography machine at 230 MJ / cm 2 Expose the exposed photoresist-current collector-porous GaN-sapphire structure in developer and deionized water for 30 seconds each, and blow dry the structure with nitrogen to obtain a photoresist-current collector-porous GaN-sapphire structure after protective photolithography, wherein the photoresist covers the upper surface of the current collector and the porous GaN on both sides of the structure;

[0042] 4c) Under the process conditions of 500 W power, Cl2 / BCl3 mixed gas etching gas, and 200 nm etching depth, the photoresist-current collector-porous GaN-sapphire structure after protective photolithography was subjected to ICP etching to remove the porous GaN without photoresist position, and the remaining photoresist after ICP etching was stripped by acetone solution, and then the body with the photoresist stripped was immersed in alcohol and deionized water in turn and allowed to stand for 1 min each, and then taken out and dried with nitrogen, and rapid thermal annealing was performed at 850° C. for 35 s in a nitrogen atmosphere to obtain the main structure of the micro supercapacitor, wherein the porous GaN located between the current collectors with the pattern of interdigitated lines was removed.

[0043] Step 5) Encapsulating the main structure of the micro supercapacitor:

[0044] PVA-H2SO4 gel electrolyte is drop-coated on one side of the current collector in the main structure of the micro-supercapacitor and cured for 24 hours. The positive and negative leads are respectively led out from the porous GaN on the two sides of the main structure of the micro-supercapacitor. The polydimethylsiloxane film PDMS is encapsulated on one side of the current collector in the main structure of the micro-supercapacitor where the positive and negative leads are led out, to make a high-temperature resistant micro-supercapacitor based on porous GaN.

[0045] Example 2. The implementation process and structure of this example are the same as those of Example 1, and only some parameters are adjusted. In this example, the time for ultrasonic cleaning of the sapphire insulating substrate is 1 minute. The temperature and pressure parameters of the MOCVD reaction chamber are set to 900°C and 18 Torr respectively. The voltage and time for etching the GaN-sapphire structure in this example are 18V and 18min respectively. The parameters of the glue spinning machine in this example are set to 600r / s low speed for 3s of spin coating and 2800r / s high speed for 25s of spin coating. The exposure dose of the photolithography machine in this example is 210MJ / cm 2 The deposited current collector and thickness of this embodiment are Ni / Au and 10nm / 50nm respectively. The annealing temperature and time of this embodiment are 800°C and 25s respectively. The electrolyte applied by drop coating in this embodiment is LiCl-gel electrolyte.

[0046] Example 3. The implementation process and structure of this example are the same as those of Example 1, and only some parameters are adjusted. In this example, the time for ultrasonic cleaning of the sapphire insulating substrate is 3 minutes. The temperature and pressure parameters of the MOCVD reaction chamber are set to 1200°C and 22 Torr respectively. The voltage and time for etching the GaN-sapphire structure are 22V and 22 minutes respectively. The parameters of the glue spinning machine in this example are set to 1000r / s low speed for 8s first and 3200r / s high speed for 35s later. The exposure dose of the photolithography machine in this example is 250MJ / cm 2 The deposited current collector and thickness of this embodiment are Ti / Al and 20nm / 80nm respectively. The annealing temperature and time of this embodiment are 900°C and 45s respectively. The electrolyte applied by drop coating in this embodiment is EG-LiCl mixed gel electrolyte.

[0047] The above-mentioned embodiments only express one implementation mode of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention. For example, in addition to the PVA-H2SO4, LiCl-gel gel electrolyte, and EG-LiCl mixed gel electrolyte used in the specific embodiments, other acid-base gel electrolytes, salt-in-water and ionic liquid gel electrolytes can also be used; these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the attached claims.

Claims

1. A method for preparing a high temperature resistant micro supercapacitor based on porous GaN, characterized in that: The steps include: (1) Pre-treating the insulating substrate; (2) Growing porous GaN on the upper surface of an insulating substrate: Depositing a GaN film on a pre-treated sapphire insulating substrate, etching the deposited GaN-sapphire structure, and then performing pattern photolithography on the etched porous GaN-sapphire structure to obtain a patterned photoresist-porous GaN-sapphire structure with a photoresist pattern of interdigitated lines; (3) Obtaining a patterned current collector-porous GaN-sapphire structure: Depositing any one or more of Ti / Al / Ni / Au on the side of the patterned photoresist-porous GaN-sapphire structure facing the porous GaN and the patterned photoresist, and stripping the photoresist from the current collector / photoresist-porous GaN-sapphire structure formed by the deposition to obtain a patterned current collector-porous GaN-sapphire structure with interdigitated lines as the current collector pattern; (4) Obtaining the main structure of the micro supercapacitor: The obtained patterned current collector-porous GaN-sapphire structure with interdigitated lines is subjected to protective photolithography, and the photoresist-current collector-porous GaN-sapphire structure formed by the protective photolithography is subjected to inductively coupled plasma ICP etching, and then the photoresist-current collector-patterned porous GaN-sapphire structure after ICP etching is stripped and annealed to obtain a micro supercapacitor main structure; (5) Encapsulating the main structure of the micro supercapacitor: The positive and negative electrode leads are respectively led out from the porous GaN on the two sides of the main structure of the micro supercapacitor, and the polydimethylsiloxane film PDMS is encapsulated on one side of the current collector in the main structure of the micro supercapacitor where the positive and negative electrode leads are led out, completing the preparation of the high-temperature resistant micro supercapacitor based on porous GaN.

2. The method according to claim 1, characterized in that In step (1), the insulating substrate is pretreated, and the implementation steps are as follows: Deionized water, analytical grade acetone and isopropanol are used in sequence to ultrasonically clean the insulating substrate made of sapphire for 1-2 minutes, and the cleaned insulating substrate is blown dry by nitrogen to achieve pretreatment.

3. The preparation method according to claim 1, characterized in that The step (2) of growing porous GaN on the upper surface of the insulating substrate is implemented by: (2a) Using a novel vapor phase epitaxial growth technology MOCVD or molecular beam epitaxy MBE method to deposit GaN thin film on a pre-treated insulating substrate to form a GaN-sapphire structure; (2b) using a GaN-sapphire structure and metal Pt as a working electrode and a counter electrode, respectively, electrochemically etching the GaN-sapphire structure with an oxalic acid solution to obtain a porous GaN-sapphire structure; (2c) uniformly coating the porous GaN surface of the porous GaN-sapphire structure with glue, and pre-baking the uniformly coated photoresist-porous GaN-sapphire structure with a hot plate; (2d) The pre-baked photoresist-porous GaN-sapphire structure is exposed by a photolithography machine using an interdigitated mask, and then the exposed photoresist-porous GaN-sapphire structure is immersed in a developer and deionized water in turn for development treatment and then dried with nitrogen to achieve pattern lithography of the porous GaN-sapphire structure after electrochemical etching, thereby obtaining a patterned photoresist-porous GaN-sapphire structure with an interdigitated line pattern and a line width of 2 to 50 μm.

4. The preparation method according to claim 1, characterized in that The step (3) of obtaining a patterned current collector-porous GaN-sapphire structure, wherein the deposition is performed using an electron beam evaporation device, and the steps of stripping the photoresist from the current collector / photoresist-porous GaN-sapphire structure formed by the deposition are as follows: The interdigitated line-shaped photoresist and the deposited layer on the surface of the current collector / photoresist-porous GaN-sapphire structure are stripped off with an acetone solution, and the body with the deposited layer pattern of interdigitated lines after the photoresist is stripped off is cleaned with alcohol and deionized water in turn and then blown dry with nitrogen to obtain a patterned current collector-porous GaN-sapphire structure with the current collector pattern of interdigitated lines.

5. The preparation method according to claim 1, characterized in that: The main structure of the micro-supercapacitor described in step (4) is obtained by: (4a) uniformly coating the porous GaN and one side of the current collector in the patterned current collector-porous GaN-sapphire structure in which the current collector pattern is interdigitated lines, and then pre-baking on a hot plate to obtain a photoresist-current collector-porous GaN-sapphire structure in which both the photoresist pattern and the current collector pattern are interdigitated lines and the two patterns are arranged alternately; (4b) exposing the pre-baked photoresist-current collector-porous GaN-sapphire structure, and immersing the exposed photoresist-current collector-porous GaN-sapphire structure in developer and deionized water in turn for development, and then drying the body without photoresist between the interdigitated lines of the current collector formed by the development with nitrogen gas to obtain a photoresist-current collector-porous GaN-sapphire structure after protective photolithography; (4c) The photoresist-current collector-porous GaN-sapphire structure after protective photolithography is subjected to ICP etching to remove the porous GaN without the photoresist position, and the remaining photoresist after ICP etching is stripped by acetone solution, and then the body with the photoresist stripped is cleaned, nitrogen-dried and annealed in sequence to obtain the main structure of the micro supercapacitor.

6. The preparation method according to claim 1, characterized in that: The polydimethylsiloxane film PDMS described in step (5) is encapsulated on one side of the current collector in the micro-supercapacitor main structure from which the positive and negative electrode leads are drawn, wherein the electrolyte is dripped on one side of the current collector in the micro-supercapacitor main structure before encapsulation.

7. The preparation method according to claim 6, characterized in that: The electrolyte is polyvinyl alcohol PVA-H2SO4 gel, LiCl-gel gel or ethylene glycol EG-LiCl mixed gel.

8. A high temperature resistant micro supercapacitor based on porous GaN, comprising a current collector, an electrode material and an insulating substrate stacked in sequence from top to bottom; characterized in that: The electrode material is porous GaN.

9. The high temperature resistant micro supercapacitor according to claim 8, characterized in that: The current collector is made of any one or more of Ti / Al / Ni / Au.

10. The high temperature resistant micro supercapacitor according to claim 8, characterized in that: The insulating substrate is made of sapphire.

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