A laser-induced graphene with high reflectivity and electromagnetic shielding performance based on a sandwich structure and its preparation method.

Abstract

This invention relates to the field of graphene material preparation technology, and particularly to a laser-induced graphene with high reflectivity and electromagnetic shielding performance based on a sandwich structure and its preparation method. The preparation method includes the following steps: placing polyimide paper on a vacuum adsorption stage; setting femtosecond laser parameters and defocus distance; designing the laser scanning path using computer-aided SCA software; generating laser-induced graphene on two opposite surfaces of the polyimide paper to obtain laser-induced graphene with a sandwich structure. By adjusting the femtosecond laser parameters and defocus distance, combined with SCA software that controls the laser scanning path, LIGs are prepared on both sides of the polyimide. The thickness of the LIGs on both sides is controlled so that the middle part of the polyimide is completely induced into graphene to act as a conductive layer, thereby improving the conductivity of the graphene. The remaining polyimide acts as a PI framework to prevent over-carbonization and sample fragility, ensuring the flexibility of the sample. The surface resistivity of the product is stably 4.5 Ω / sq, and the reflectivity is as high as 93%.

Description

Technical Field

[0001] This invention relates to the field of graphene materials technology, and in particular to a laser-induced graphene with high reflectivity and electromagnetic shielding performance based on a sandwich structure and its preparation method. Background Technology

[0002] Laser-induced graphene (LIG) has attracted great interest due to its excellent electrical, mechanical, chemical, and thermal properties, and has been widely used in various flexible devices, electromagnetic shielding, batteries, supermicrocapacitors, and energy storage. Since 2014, researchers have been elucidating the synthesis mechanism of LIG from various aspects, including different laser parameters, precursor materials, and laser environments, and have effectively improved the quality of LIG, achieving effective control over its morphology and properties. Currently, most LIG fabrication utilizes traditional CO2 lasers to induce polyimide films into laser-induced graphene. However, CO2 lasers have Gaussian beam characteristics, exhibiting highly localized and non-uniform intensity distribution, and the controllable laser parameters are limited. The conductivity of the prepared LIG still lags significantly behind that of metals. In addition, the inhomogeneity of PI leads to large errors in the surface resistivity and electromagnetic wave reflection ability of LIG prepared with the same laser parameters, making stable production difficult.

[0003] The simplest way to achieve high reflectivity in pure LIG is to improve conductivity, i.e., appropriately increase the laser power to completely grapheneize the PI paper. However, this results in samples that are too brittle and difficult to bend, making them unsuitable for practical applications. Furthermore, excessive laser power can lead to over-carbonization, damaging the porous structure of the previously stabilized graphene and increasing resistance.

[0004] Currently, most methods to significantly improve the electromagnetic reflection capability of LIGs involve adding composite materials to LIGs to enhance conductivity. These methods include coating the LIG surface with conductive materials or using electrochemical deposition to attach conductive metals to the porous structure of the LIG. However, the surface coating method suffers from poor adhesion between the surface layer and the LIG, and the surface metal layer is easily damaged, resulting in a short service life. While the electrochemical deposition method can bind metal particles to the porous inner wall of the LIG, it cannot achieve one-step synthesis, making the process complex and increasing the manufacturing cost and time of LIGs.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure and its preparation method, aiming to solve the problems of short service life or complex process in existing methods for improving the ability of LIG to reflect electromagnetic waves.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on a sandwich structure, comprising the following steps:

[0009] Place the polyimide paper on the vacuum adsorption stage;

[0010] By setting femtosecond laser parameters and defocus distance, and using computer-aided SCA micromachining software to design the laser scanning path, laser-induced graphene is generated on two opposite surfaces of the polyimide paper, resulting in a sandwich-structured graphene material.

[0011] The method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on sandwich structure, wherein the step of placing polyimide paper on a vacuum adsorption stage further includes: pressing the four edges of the polyimide paper with a glass slide mold.

[0012] The method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on sandwich structure, wherein the femtosecond laser parameters include laser wavelength, repetition frequency, laser pulse width, and average power.

[0013] The method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on a sandwich structure, wherein the laser wavelength is selected from one of near-infrared 1030nm, visible light 515nm, and ultraviolet 343nm; the repetition frequency is 555kHz-1111kHz; the laser pulse width is 220fs-290fs; and the average power is 0.6W-1.5W.

[0014] The method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on sandwich structure, wherein the defocus distance is 0.2mm-0.3mm.

[0015] The method for preparing laser-induced graphene with high electromagnetic shielding performance based on sandwich structure, wherein the parameters of the SCA micromachining software include laser scanning speed, laser pulse, and laser density.

[0016] The method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on sandwich structure, wherein the laser scanning speed is 28-60 mm / s; the laser pulses are 400-550 times; and the laser density is 55-68 pulses / mm.

[0017] The method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on sandwich structure, wherein the laser scanning path includes: first moving in a Z-shape along the x-direction of the polyimide paper, and then moving in a Z-shape along the y-direction of the polyimide paper.

[0018] A laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure is prepared using the aforementioned method for preparing laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure.

[0019] The laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure comprises a composite layer and graphene layers disposed on opposite sides of the composite layer; the composite layer is composed of a polyimide framework and a graphene conductive layer.

[0020] Beneficial Effects: This invention provides a laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure and its preparation method. The preparation method includes the following steps: placing polyimide paper on a vacuum adsorption stage; setting femtosecond laser parameters and defocus distance; designing the laser scanning path using computer-aided SCA micromachining software; generating laser-induced graphene on two opposite surfaces of the polyimide paper to obtain laser-induced graphene with a sandwich structure. This invention, by controlling the femtosecond laser parameters and defocus distance, combined with SCA micromachining software that controls the laser scanning path, prepares LIG along the x and y sides of the polyimide paper respectively. By controlling the thickness of the LIG on both sides, the middle portion of the polyimide is cleverly induced to become graphene, acting as a conductive layer. This connects the graphene on both sides, improving conductivity. The remaining polyimide acts as a PI framework, preventing over-carbonization and sample fragility, ensuring sample flexibility. The sandwich-structured graphene prepared by this method reduces costs and shortens the preparation cycle, while achieving a stable sheet resistivity of 4.5 Ω / sq and a reflectivity as high as 93%. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process flow for a method of preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on a sandwich structure according to the present invention.

[0022] Figure 2 This is a schematic diagram of a glass slide mold;

[0023] Figure 3 A schematic diagram of the scan path set for SCA micromachining software;

[0024] Figure 4 This is a scanning electron microscope image of the intermediate residual PI portion of LIG as a conductive layer, as characterized by SEM in Example 1.

[0025] Figure 5 This is a scanning electron microscope image of the intermediate residual PI, which is not carbonized and serves as the PI framework, under SEM characterization of LIG in Example 1.

[0026] Figure 6 This is an EDS layered image of LIG in Example 1;

[0027] Figure 7 The graph shows the LIG surface resistance data of LIG at different power levels in Example 1;

[0028] Figure 8 This is a diagram showing the electromagnetic shielding coefficient corresponding to the optimal surface resistance of LIG in Example 1. Detailed Implementation

[0029] This invention provides a laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0031] like Figure 1 As shown, this invention provides a method for preparing laser-induced graphene with high reflectivity electromagnetic shielding performance based on a sandwich structure, comprising the following steps:

[0032] Step S10: Place the polyimide paper on the vacuum adsorption stage;

[0033] Step S20: Set the femtosecond laser parameters and defocus distance, design the laser scanning path using computer-aided SCA micromachining software, and generate laser-induced graphene on the two opposite surfaces of the polyimide paper to obtain laser-induced graphene with a sandwich structure.

[0034] In this embodiment, polyimide (PI) paper is placed on a vacuum adsorption stage. Using SCA micromachining software with computer-controlled laser scanning path, femtosecond laser parameters and defocus distance are set to prepare laser-induced graphene (LIG) along the x and y directions on both sides of the PI paper. By controlling the thickness of the LIG on both sides, the entire PI in the middle is induced to become graphene, acting as a conductive layer. The connection between the two sides of the graphene increases conductivity, thereby increasing electromagnetic wave reflection. The remaining PI acts as a PI framework, preventing over-carbonization and sample brittleness, ensuring sample flexibility. The graphene material prepared using this method has a sandwich structure, exhibiting not only flexibility but also high reflectivity. Furthermore, this preparation method can reduce costs and shorten the preparation cycle while achieving a stable sheet resistivity of 4.5 Ω / sq and a reflectivity as high as 93% for the sandwich-structured graphene material.

[0035] In some embodiments, before step S10, the method further includes the step of cleaning and drying the polyimide paper. Specifically, cleaning and drying the polyimide paper includes the following steps: cleaning the polyimide paper successively with anhydrous ethanol and deionized water, and then placing the cleaned polyimide paper in a vacuum oven for drying to obtain clean polyimide paper; the drying temperature is 55-65℃, and the drying time is 1.5-2.5 hours. After cleaning the PI paper with anhydrous ethanol and deionized water, a clean PI paper surface can be obtained, and then drying is used to remove moisture from the surface of the PI paper.

[0036] In some embodiments, step S10, the step of placing the polyimide paper on the vacuum adsorption stage, further includes: pressing the edges of the polyimide paper with a glass slide mold, which can ensure that the surface of the PI paper is strictly adsorbed onto the worktable, such as... Figure 2 As shown.

[0037] Existing techniques typically involve adhering PI paper to a glass substrate or other substrate before adsorbing it onto a worktable. However, PI paper is fibrous and its surface is not actually flat. Therefore, under a 10x microscope, there is an error of 0.1-0.3 μm in the focusing depth at different positions. This leads to large quality errors in graphene produced with the same laser parameters, resulting in significant conductivity errors and a repeatability of only 70%, failing to consistently produce the desired results. Therefore, this embodiment directly adsorbs the PI paper onto a vacuum adsorption stage. However, PI paper is actually porous and permeable, making it difficult to adsorb directly. Therefore, a prepared glass slide mold is used to cover the four edges of the PI paper, reserving a rectangular double-sided processable area. The mold increases the adsorption area; a larger surface area allows for greater total adsorption, enabling the PI paper to be adsorbed flatly onto the worktable with similar focusing depths at different positions. By using the glass slide mold to press down the four edges of the polyimide paper, the repeatability of the LIG conductivity can reach 95-99%, achieving stable fabrication.

[0038] In some implementations, the SCA micromachining software has the following advantages:

[0039] 1. High-precision and accurate laser control can be achieved through trajectory planning;

[0040] 2. Achieve the shortest processing time dynamics and laser power by optimizing the use of the scanner;

[0041] 3. Advanced Spot Distance Control (SDC) function.

[0042] In some embodiments, the femtosecond laser parameters include laser wavelength, repetition rate, laser pulse width, and average power.

[0043] In some embodiments, the laser wavelength is selected from one of near-infrared 1030nm, visible light 515nm, and ultraviolet 343nm; the repetition frequency is 555kHz-1111kHz; the laser pulse width is 220fs-290fs; and the average power is 0.6W-1.5W.

[0044] Specifically, the laser wavelengths used in this embodiment are near-infrared (1030nm), visible light (515nm), and ultraviolet (343nm). When the laser beam irradiates the target material, a small portion of the laser energy is absorbed and converted into heat energy to heat the target material, while the remaining energy is reflected or scattered. Therefore, the light in the above three wavelength bands is absorbed by the PI paper, achieving carbonization and thus inducing it to become graphene.

[0045] The repetition rate refers to the number of pulses emitted per second, which is one of the key parameters controlling the heat accumulation process during LIG formation. A high repetition rate can reduce thermal damage and burning to the substrate while converting PI into LIG. A low repetition rate causes the photothermal energy deposited by each pulse to disappear before heat accumulation, thus preventing LIG formation. Therefore, a suitable repetition rate is 555kHz-1111kHz. Pulsed lasers can emit photons in a short time to generate higher peak power and quickly reach the required carbonization and graphitization temperatures. The size of the heat-affected zone is proportional to the square root of the pulse duration. When the pulse duration is less than the time required to distribute the pulse energy as heat on the substrate, the thermal effect can be ignored. Therefore, a laser pulse width of 220fs-290fs can achieve the technical effect of this embodiment. The choice of laser power depends on the type of carbon precursor, as well as the required LIG characteristics and other control parameters. To obtain a highly conductive LIG, the laser power must exceed a certain threshold to produce a photothermal effect. Appropriately increasing the average laser power can produce a higher quality LIG. However, when the laser power is too high, it will lead to over-carbonization, increased resistance, and even carbonization into carbon powder. Therefore, 0.6W-1.5W is selected as the average power of the femtosecond laser.

[0046] In a preferred embodiment, the laser wavelength is near-infrared 1030nm; the repetition frequency is 1111kHz; the laser pulse width is 220fs; and the average power is 0.9W.

[0047] In some embodiments, the defocus distance is 0.2 mm to 0.3 mm. Defocusing controls the distance between the objective lens and the focal plane, thereby determining the size of the laser spot on the PI substrate. A larger laser spot allows for more uniform illumination and more overlapping scanning, effectively increasing the laser density to obtain LIG with optimal conductivity.

[0048] In some embodiments, the parameters of the SCA micromachining software include laser scanning speed, laser burst, and laser density; the femtosecond laser is a single-pulse laser, and the speed, burst, and density can be adjusted in combination to strictly control the number of pulses and the energy of a single pulse, thereby controlling the size and depth of the PI carbonization region.

[0049] In some embodiments, the laser scanning speed is 28-60 mm / s; the laser pulses are 400-550 times; and the laser density is 55-68 pulses / mm.

[0050] Specifically, based on a determined femtosecond laser average power, increasing the scanning speed to a certain level enables rapid fabrication of LIG with good reflectivity. However, excessively high scanning speeds result in insufficient carbonization temperatures due to short contact times, preventing graphene formation. Conversely, excessively low scanning speeds lead to excessively high carbonization temperatures due to long contact times, resulting in carbon powder formation. The laser burst parameter controls the number of laser pulses output by the SCA (Superconducting Acoustic Coil Atomizer) at a time, i.e., how many times a single point is targeted. Selecting laser pulses of 400-550 nm yields graphene materials with high reflectivity. The laser density can be used to control the SCA to determine the carbonization unit, i.e., how many points are targeted per millimeter.

[0051] Furthermore, laser scanning speed × laser pulse × laser density = laser operating frequency. The laser operating frequency is less than the laser repetition frequency, which is equivalent to fine-tuning the repetition frequency to determine the size of the spot and the size of the heat-affected zone.

[0052] In a preferred embodiment, the laser scanning speed is 28 mm / s; the laser pulse count is 500; and the laser density is 68 pulses / mm.

[0053] In some embodiments, in step S30, when designing the laser scanning path using computer-aided SCA micromachining software, after adjusting the laser scanning speed, laser pulse, and laser density, the thermal effect may be weaker than when the average power was previously selected. Therefore, the average power of the femtosecond laser parameters can be appropriately increased or decreased until the optimal reflectivity is achieved.

[0054] In some embodiments, the laser scanning path includes: first moving in a zigzag pattern along the x-direction of the polyimide paper, and then moving in a zigzag pattern along the y-direction of the polyimide paper. The pattern is designed using computer-aided SCA micromachining software, such that the scanning path first moves in a zigzag pattern along the x-direction and then along the y-direction. A schematic diagram of the scanning path is shown below. Figure 3 As shown. Currently, LIGs are generally fabricated along the x-axis, or through two processing steps along the x and y axes. This invention, however, utilizes the loop language of the SCA micromachining software to achieve multiple laser scans in a single step, significantly reducing manufacturing time and costs.

[0055] Specifically, the femtosecond laser used in this invention is 343-1030nm, and it is a pulsed laser rather than a continuous laser. Multiple parameters can be adjusted, resulting in lower resolution and less damage to the substrate. This allows for fine-tuning of the microstructure of LIG, leading to higher reflectivity.

[0056] In addition, the present invention also provides a laser-induced graphene with high reflectivity electromagnetic shielding performance based on a sandwich structure, which is prepared by the method of preparing the laser-induced graphene with high reflectivity electromagnetic shielding performance based on a sandwich structure.

[0057] In this embodiment, femtosecond laser parameters, some parameters controlled by SCA micromachining software, and defocus distance are combined to jointly control the size and depth of the PI carbonization region, thereby controlling the thickness of the sandwich-structured graphene. Furthermore, the degree of carbonization of the intermediate PI layer is cleverly controlled, serving both as a conductive layer connecting the upper and lower graphene layers to improve conductivity, and as a PI framework to prevent the sample from becoming brittle due to excessive carbonization, ensuring sample flexibility and extending its actual lifespan.

[0058] In some embodiments, the femtosecond laser-induced sandwich structure graphene material includes a composite layer and graphene layers disposed on opposite sides of the composite layer; the composite layer is composed of a polyimide framework and a graphene conductive layer.

[0059] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0060] Example 1

[0061] This embodiment provides a method for stably preparing high-conductivity sandwich-structured graphene materials, specifically including the following steps:

[0062] (1) Take the size as 40×25mm 2 PI paper with a thickness of about 0.1 mm was used as a precursor. It was washed with anhydrous ethanol and deionized water, and then dried in a vacuum oven at 60°C for 2 hours.

[0063] (2) Place the dried PI paper on the vacuum adsorption stage and press it with a glass slide mold around the edges of the PI paper to ensure that the surface of the PI paper is strictly adsorbed onto the worktable. Reserve a rectangular double-sided processable area with an area of ​​24mm*12mm-30mm*20mm.

[0064] (3) Preset femtosecond laser parameters: laser wavelength is 1030nm; laser pulse frequency is 1111kHz; laser power is 0.9w.

[0065] (4) Design the pattern using computer-aided SCA micromachining software, so that the scanning path first follows a Z-shape along the x-direction and then along the y-direction; the scanning path diagram is shown below. Figure 3As shown, the scanning path first moves in a zigzag pattern along the x-direction, then the gray jumper line moves to the designated position and continues in a zigzag pattern along the y-direction to complete the processing in one step. Multiple laser scans can be achieved in just one step, ultimately resulting in a 25×14mm design. 2 The grid pattern was determined; the laser parameters in the SCA micromachining software were set as follows: speed = 28 mm / s, burst = 500, density = 68. Combined with the defocusing method, the defocusing distance was set to 0.3 mm.

[0066] (5) Under the above steps, a femtosecond laser was used to irradiate one side of the PI paper in an air environment at room temperature, and the conductivity of the single-sided LIG was 8Ω / sq.

[0067] (6) Based on the above, repeat the above operation on the other side of the PI paper to finally obtain a high reflectivity sandwich structure graphene material.

[0068] The SEM representation image of LIG is as follows: Figure 4-5 As shown, the PI in the middle layer of the prepared sandwich-structured graphene material can be used as... Figure 4 The conductive layer shown can also be used as... Figure 5 The PI skeleton shown.

[0069] The carbonization of LIG can be observed through EDS characterization, such as... Figure 6 As shown, both the top and bottom sides are completely carbonized into graphene.

[0070] Under different laser parameter settings, by Figure 7 It can be seen that the conductivity eventually stabilizes at a maximum of 4.5 Ω / sq.

[0071] Depend on Figure 8 As can be seen, the LIG with optimal conductivity achieves a reflectivity of up to 93% in the 8.2-12.4 GHz band, demonstrating excellent electromagnetic reflection capabilities. Clearly, higher conductivity increases impedance mismatch and strengthens reflection; that is, higher conductivity translates to a stronger ability to reflect electromagnetic waves.

[0072] In this embodiment, by controlling the combined parameters of the femtosecond laser, the thickness of the upper and lower graphene layers can be controlled after double-sided scanning preparation, thereby indirectly controlling the average thickness of the middle PI to 10-20 μm. In a very ingenious way, the middle part of PI can be completely induced to become graphene to act as a conductive layer, connecting the graphene on both sides to improve conductivity, while the other part of the residual PI acts as a PI skeleton, preventing the sample from becoming brittle due to over-carbonization, ensuring the flexibility of the sample, and extending the actual service life of the sample.

[0073] In summary, this invention provides a laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure and its preparation method. The preparation method includes the following steps: placing polyimide paper on a vacuum adsorption stage; setting femtosecond laser parameters and defocus distance; designing the laser scanning path using computer-aided SCA micromachining software; generating laser-induced graphene on two opposite surfaces of the polyimide paper; and obtaining laser-induced graphene with a sandwich structure. This invention, by controlling the femtosecond laser parameters and defocus distance, combined with SCA micromachining software that controls the laser scanning path, prepares LIGs along the x and y sides of the polyimide paper. By controlling the thickness of the LIGs on both sides, the middle portion of the polyimide is cleverly induced to become entirely graphene, acting as a conductive layer. This connects the graphene on both sides, improving conductivity. The remaining polyimide acts as a PI framework, preventing over-carbonization and sample fragility, and ensuring sample flexibility. The sandwich-structured graphene material prepared by this method reduces costs and shortens the preparation cycle, while achieving a stable sheet resistivity of 4.5 Ω / sq and a reflectivity as high as 93%.

[0074] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for the preparation of laser-induced graphene based on sandwich structure with high reflection electromagnetic shielding performance, characterized by, Including the following steps: The polyimide paper was cleaned with anhydrous ethanol and deionized water, and then placed in a vacuum oven and dried at 55-65℃ for 1.5-2.5 hours to obtain clean polyimide paper. Place the clean polyimide paper on the vacuum adsorption stage; By setting femtosecond laser parameters and defocus distance, and using computer-aided SCA micromachining software to design the laser scanning path, laser-induced graphene is generated on two opposite surfaces of the polyimide paper, resulting in laser-induced graphene with a sandwich structure. The step of placing the polyimide paper on the vacuum adsorption stage further includes: pressing the four edges of the polyimide paper with a glass slide mold; The femtosecond laser parameters include laser wavelength, repetition rate, laser pulse width, and average power; the laser wavelength is selected from one of near-infrared 1030nm, visible light 515nm, and ultraviolet 343nm; the repetition rate is 555kHz-1111kHz; the laser pulse width is 220fs-290fs; the average power is 0.6W-1.5W; and the defocus distance is 0.2mm-0.3mm. The parameters of the SCA micromachining software include laser scanning speed, laser pulse, and laser density; the laser scanning speed is 28-60 mm / s; the laser pulse count is 400-550 times; and the laser density is 55-68 pulses / mm. The laser scanning path includes: first moving in a zigzag pattern along the x-direction of the polyimide paper, and then moving in a zigzag pattern along the y-direction of the polyimide paper; The femtosecond laser emitting the femtosecond laser has a wavelength of 343-1030nm, and the femtosecond laser is a pulsed laser. The laser-induced graphene with high electromagnetic shielding performance based on a sandwich structure includes a composite layer and graphene layers disposed on opposite sides of the composite layer; the composite layer is composed of a polyimide framework and a graphene conductive layer.

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