Broadband regulation and control wave absorber based on multilayer graphene capacitor and preparation method of broadband regulation and control wave absorber

Abstract

The invention discloses a broadband regulation and control wave absorber based on a multilayer graphene capacitor and a preparation method of the broadband regulation and control wave absorber, and belongs to the technical field of materials. The wave absorber is formed by compounding a plurality of layers of graphene capacitors; each layer of graphene capacitor serves as a layer of structural unit of the Jaumann absorber and is composed of a graphene material connected with an external power supply electrode, a high-resistance material and an ionic liquid electrolyte between the graphene material and the high-resistance material. According to the wave absorber, aiming at different absorption target frequency bands, the surface square resistance of the graphene electrode in each layer of capacitor is changed by regulating and controlling the bias voltage of an external direct current power supply corresponding to each layer of graphene capacitor, so that a corresponding impedance gradient matching model is converted, different Jaumann absorber structures are constructed, and the wave absorption efficiency is improved. And directional absorption of electromagnetic waves of different frequency bands is realized.

Description

Technical Field

[0001] The invention relates to a broadband control absorber based on a multilayer graphene capacitor and a preparation method thereof, and belongs to the technical field of materials. Background Art

[0002] With the rapid development of radar detection and guidance and tracking technology in various countries around the world, aircraft are facing more severe countermeasures and are more dependent on advanced radar wave absorbing materials (i.e., absorbing materials) to reduce radar scattering cross-sections to improve survivability and penetration capabilities. According to the form of use, absorbing materials can be divided into two categories: coating type and structural type. Compared with the coating type, the structural absorbing material can make full use of its internal thickness space to design the absorbing structure without adding additional coating weight, so it has a broader application prospect. However, the full coverage broadband absorption performance of the structural absorbing material is very dependent on the large structural thickness, which is difficult to meet the requirements of "thin, light, wide, and strong" for new high-efficiency absorbing materials. More importantly, once the internal structure and material are designed, their response frequency band and absorption characteristics are fixed, and they cannot effectively absorb electromagnetic waves outside the response frequency band. However, in the face of complex electromagnetic environments, aircraft may need to respond to radar waves of different scanning frequency bands in turn during the entire flight process. The absorbing material with a single fixed absorption bandwidth cannot meet the performance requirements of adapting to complex electromagnetic environments. Therefore, the research and development of intelligent broadband controllable absorbers that can cope with multi-band radar waves has obvious scientific research value and broad application prospects.

[0003] In recent years, researchers have constructed dynamically adjustable absorbing materials and devices based on graphene capacitors, using the principle that the surface square resistance of graphene materials can be adjusted under bias voltage to achieve changes in the electromagnetic wave absorption peak of the material. However, this single-layer graphene capacitor is subject to the limited range of graphene resistance change, and has the disadvantages of a narrow absorption frequency band and a small response bandwidth control range. In order to change this inherent disadvantage, many reported cases usually adopt the modification of graphene capacitors, such as patent CN202011095278.3 adds oxide absorbing interlayer materials to graphene capacitors, patents CN202110756366.1 and CN105932426A add a series of metal microresonators to the surface of graphene capacitors, and patents CN202410147935.6, CN110783714A, and CN110797665A design and add a layer of periodic structure units or frequency selective surfaces to graphene capacitors. However, many designs reported so far, including the above-mentioned cases, are based on single-layer graphene capacitors, and there are no related inventions of multilayer graphene capacitors. Moreover, despite the assistance of the above-mentioned super-surface design and other measures, it is still difficult to meet the performance expectations of large-scale regulation of the absorption band within the ultra-wide frequency range of 2-18 GHz. In addition, the disclosed invention contents of the above-mentioned patents all have obvious disadvantages such as high difficulty in assembly process, complex structural regulation mechanism, and limited response frequency band regulation range. They are not suitable for the requirements of simple absorber preparation, convenient operation, precise control, environmental adaptability, and stable performance. Therefore, high-performance broadband control absorbers that meet the above requirements are still under research and development. Summary of the invention

[0004] The purpose of the present invention is to provide a broadband controllable absorber based on a multilayer graphene capacitor and a preparation method thereof, so as to meet the need for intelligent control of the absorption frequency band in a complex electromagnetic environment.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A broadband controllable absorber based on a multilayer graphene capacitor is composited with multilayer graphene capacitors; each layer of graphene capacitor serves as a structural unit of a Jaumann absorber, which is composed of a graphene material connected to an external power electrode, a high resistance material, and an ionic liquid electrolyte between the two.

[0007] A method for preparing a broadband controllable absorber based on a multilayer graphene capacitor comprises the following steps:

[0008] 1) A few-layer graphene material is applied to a polymer film to form a first electrode, a high-resistance carbon paste is applied to another layer of polymer film by screen printing to form a second electrode, and an ionic liquid electrolyte is infiltrated into a diaphragm paper or a water-absorbing paper to form an electrolyte layer;

[0009] 2) printing silver electrodes on the first electrode plate and the second electrode plate by screen printing, and connecting the electrodes of the two electrodes to an external DC power supply by copper wires; forming a graphene capacitor by sandwich structure with the first electrode plate, the electrolyte layer, and the second electrode plate, and encapsulating the graphene capacitor with insulating glue; preparing a plurality of graphene capacitors, wherein the intrinsic square resistance of the graphene material used in each graphene capacitor has a gradient difference;

[0010] 3) Laying down a plurality of graphene capacitors in order of intrinsic square resistance gradient, applying adhesive between the layers, composite curing the graphene capacitors of each layer, and assembling to obtain a broadband controllable absorber;

[0011] 4) A different bias voltage is set on each layer of graphene capacitor, and the square resistance of each layer of graphene capacitor changes with the bias voltage, forming a different impedance gradient matching structure to change the response frequency band and absorption bandwidth of the broadband control absorber.

[0012] Furthermore, the few-layer graphene material is a continuous or discontinuous single-layer or multi-layer graphene material.

[0013] Furthermore, the polymer film is selected from one or more of PET (polyethylene terephthalate), PI (polyimide), PP (polypropylene), PVC (polyvinyl chloride), and PS (polystyrene) films.

[0014] Furthermore, the adhesive is selected from one or more of silicone glue, acrylic glue, epoxy glue, polyurethane glue, and inorganic glue.

[0015] Furthermore, the ionic liquid electrolyte is diethylmethyl-(2-methoxyethyl)ammoniumbis(trifluoromethanesulfonyl)imide.

[0016] Furthermore, the intrinsic square resistance of the graphene material is in the range of 400-2000Ω / sq.

[0017] Furthermore, the bias voltage is in the range of 0-16V.

[0018] Furthermore, the number of the graphene capacitors is 2-10.

[0019] Furthermore, the intrinsic square resistance of each layer of graphene capacitor was designed using CST Studio electromagnetic design software, and the square resistance values ​​of each layer of graphene capacitor under different bias voltages were obtained.

[0020] The technical effects achieved by the present invention are as follows:

[0021] Based on the electromagnetic wave transmission and loss mechanism, the present invention combines electromagnetic field theory with material application, combines the Jaumann absorber structure with the graphene bias voltage induced square resistance modulation mechanism, and proposes a broadband control absorber based on a multilayer graphene capacitor. For different absorption target frequency bands, the bias voltage of each layer of graphene capacitor is adjusted to change the surface square resistance of the graphene electrodes in each layer of capacitor, thereby converting the corresponding impedance gradient matching model to achieve directional absorption of electromagnetic waves in different frequency bands. The multilayer graphene capacitor is a flexible material that is bendable as a whole and can change the curvature according to the needs of specific application scenarios. The present invention realizes the intelligent wave absorbing function of directionally adjustable target absorption frequency bands in the frequency range of 2-18GHz under the limitation of thinner material thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a broadband controllable absorber based on a multilayer graphene capacitor according to an embodiment is shown.

[0023] Figure 2 A schematic diagram of a graphene capacitor sandwich structure of an embodiment is shown.

[0024] Figure 3 A reflectivity test curve chart of the intelligent broadband control absorber of the embodiment is shown. DETAILED DESCRIPTION

[0025] In order to make the various technical features and advantages or technical effects in the above technical solutions of the present invention more obvious and easy to understand, they are described in detail below with reference to the accompanying drawings.

[0026] The embodiment of the present invention discloses a broadband controllable absorber based on a multilayer graphene capacitor, such as Figure 1 The structure shown is composed of a multilayer graphene capacitor; each layer of graphene capacitor serves as a structural unit of a Jaumann absorber, which is composed of a graphene material connected to an external power electrode, a high resistance material (such as a high resistance carbon material) and an ionic liquid electrolyte between the two.

[0027] The embodiment of the present invention further discloses a broadband controllable absorber based on a multilayer graphene capacitor, which specifically includes the following preparation steps:

[0028] 1) A commercial single-layer graphene material is applied to a PET film to form a first electrode, and a high-resistance carbon paste is coated on another layer of PET film by screen printing to form a second electrode, and an ionic liquid electrolyte diethylmethyl-(2-methoxyethyl)ammoniumbis(trifluoromethanesulfonyl)imide (DEME-TFSI for short) is impregnated into a separator paper to form an electrolyte layer;

[0029] 2) Silver electrodes were printed on the first and second plates by screen printing, and the electrodes were connected to an external 6V DC power supply by copper wires; Figure 2 The sandwich structure shown comprises a first electrode plate, an electrolyte layer, and a second electrode plate to form a graphene capacitor, and an insulating glue is used to encapsulate the capacitor;

[0030] 3) According to the above steps, four graphene capacitors are prepared, namely capacitors A, B, C, and D, wherein the intrinsic square resistance of the graphene material used in capacitor A is 1800Ω / sq, the intrinsic square resistance of the graphene material used in capacitor B is 1400Ω / sq, the intrinsic square resistance of the graphene material used in capacitor C is 1000Ω / sq, and the intrinsic square resistance of the graphene material used in capacitor D is 400Ω / sq;

[0031] 4) The above four capacitors are layered in the order of ABCD, and silicone is applied between the layers to composite and solidify the graphene capacitors in each layer, and an intelligent broadband control absorber is assembled.

[0032] 5) Set up three bias voltage control schemes. In control scheme 1, the voltage settings of each layer of ABCD are 0V, 1V, 0V, and 1V in sequence. In control scheme 2, the voltage settings of each layer are 1V, 3V, 0V, and 1V in sequence. In control scheme 3, the voltage settings of each layer are 1V, 3V, 1V, and 4V in sequence. The reflectivity of the absorber is tested by the bow method. The reflectivity test results of the three control schemes in the 2-18GHz frequency band are as follows: Figure 3 As shown in the figure, by changing the bias voltage control scheme, the response frequency band and absorption bandwidth of the absorber can be significantly changed, thus achieving effective absorption of electromagnetic waves in different frequency bands.

[0033] According to the calculation results of electromagnetic design software, the present invention can establish a simulation calculation database between the graphene intrinsic square resistance of each graphene capacitor and the bias voltage and the absorber response frequency band and absorption bandwidth. According to different absorption requirements, the corresponding bias voltage control scheme can be directly selected.

[0034] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should all be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. A broadband controllable absorber based on a multilayer graphene capacitor, characterized in that: It is composed of a multilayer graphene capacitor; each layer of graphene capacitor serves as a structural unit of a Jaumann absorber, which is composed of a graphene material connected to an external power electrode, a high resistance material, and an ionic liquid electrolyte between the two.

2. A method for preparing a broadband controllable absorber based on a multilayer graphene capacitor, characterized in that: The following steps are involved: 1) A few-layer graphene material is applied to a polymer film to form a first electrode, a high-resistance carbon paste is applied to another layer of polymer film by screen printing to form a second electrode, and an ionic liquid electrolyte is infiltrated into a diaphragm paper or a water-absorbing paper to form an electrolyte layer; 2) printing silver electrodes on the first electrode plate and the second electrode plate by screen printing, and connecting the electrodes of the two electrodes to an external DC power supply by copper wires; forming a graphene capacitor by sandwich structure with the first electrode plate, the electrolyte layer, and the second electrode plate, and encapsulating the graphene capacitor with insulating glue; preparing a plurality of graphene capacitors, wherein the intrinsic square resistance of the graphene material used in each graphene capacitor has a gradient difference; 3) Laying down a plurality of graphene capacitors in order of intrinsic square resistance gradient, applying adhesive between the layers, composite curing the graphene capacitors of each layer, and assembling to obtain a broadband controllable absorber; 4) A different bias voltage is set on each layer of graphene capacitor, and the square resistance of each layer of graphene capacitor changes with the bias voltage, forming a different impedance gradient matching structure to change the response frequency band and absorption bandwidth of the broadband control absorber.

3. The preparation method according to claim 2, characterized in that: The few-layer graphene material is a continuous or discontinuous single-layer or multi-layer graphene material.

4. The preparation method according to claim 2, characterized in that: The polymer film is selected from one or more of PET, PI, PP, PVC, and PS films.

5. The preparation method according to claim 2, characterized in that: The adhesive is selected from one or more of silicone, acrylic adhesive, epoxy adhesive, polyurethane adhesive, and inorganic adhesive.

6. The preparation method according to claim 2, characterized in that: The ionic liquid electrolyte is diethylmethyl-(2-methoxyethyl)ammoniumbis(trifluoromethanesulfonyl)imide.

7. The preparation method according to claim 2, characterized in that: The intrinsic square resistance of the graphene material is in the range of 400-2000Ω / sq.

8. The preparation method according to claim 2, characterized in that: The bias voltage is in the range of 0-16V.

9. The preparation method according to claim 2, characterized in that: The number of the graphene capacitors is 2-10.

10. The preparation method according to claim 2, characterized in that: The intrinsic square resistance of each layer of graphene capacitor is designed using CST Studio electromagnetic design software, and the square resistance values ​​of each layer of graphene capacitor under different bias voltages are obtained.

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