Thick-layer porous carbon material with hydrophilic vertical microchannel array, and preparation method and application thereof

Abstract

This invention discloses a thick porous carbon material with a hydrophilic vertical microchannel array and its preparation method, belonging to the field of electrochemical energy storage. The electrode comprises an integrated thick porous carbon framework matrix with a thickness of at least 200 μm, and vertical microchannels arranged in a periodic array throughout the matrix. The inner wall surface of the vertical microchannels has a hydrophilic modification layer (water contact angle less than 90°), while the matrix body region away from the vertical microchannels is hydrophobic (water contact angle greater than 100°), thereby forming a differential wettability structure inside the electrode to promote electrolyte penetration into the deep pores. The preparation method uses pulsed laser dry scanning ablation of a dried porous carbon substrate under air conditions, utilizing the thermal localization effect to simultaneously form vertical microchannels and achieve in-situ hydrophilic modification of the inner wall, thereby improving the wetting and ion transport of the thick electrode and enhancing high-rate charge-discharge performance.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage device technology, specifically relating to a thick porous carbon electrode structure design for improving ion transport dynamics, and a laser dry processing technology based on thermal localization effect. Background Technology

[0002] With the rapid development of portable electronic devices, wearable technology, and distributed sensor networks, the market demand for high-energy-density energy storage devices is becoming increasingly urgent. Within a limited device projection area, increasing the electrode thickness (typically greater than 200 μm) to improve the areal loading of active material (typically greater than 10 mg / cm²) is one of the most direct and effective strategies to improve the device's areal energy density.

[0003] However, thick electrodes face severe kinetic challenges in practical applications, namely the "thickness-performance trade-off." Traditional thick-layer porous carbon electrodes suffer from highly tortuous internal pore structures due to the disordered stacking of active material particles or sheets. As electrode thickness increases, the diffusion path of electrolyte ions to deeper active sites lengthens significantly, and transport resistance increases exponentially. This results in insufficient ion supply to the deeper active materials during rapid charge and discharge, creating a kinetically "dead volume." Furthermore, many high-performance carbon-based framework materials (such as graphene and carbon nanotubes) are hydrophobic, and the capillary forces generated by their micro- and nano-sized pores further hinder the wetting of aqueous electrolytes, leading to actual electrode capacity far lower than theoretical values.

[0004] To improve the kinetic performance of thick electrodes, existing technologies mainly employ bottom-up assembly methods (such as magnetic field orientation and directional cryogenic casting) to construct low-torsivity ion channels. However, these processes often rely on expensive equipment and are complex, making large-scale industrial production difficult. Laser drilling technology, as a top-down processing method, is considered to have great potential. However, when processing intricate and porous carbon frameworks, existing laser processes have significant shortcomings: to prevent framework collapse or pore melting and closure due to thermal damage, a polymer sacrificial layer (such as a PVA coating) or liquid medium-assisted processing (such as underwater laser ablation) is usually required. The introduction of these auxiliary media not only increases the complexity of the process, but the huge capillary forces generated during subsequent removal processes (such as drying) can easily cause micropore closure and even introduce chemical impurities that are difficult to completely remove, thus impairing the overall electrochemical performance of the electrode.

[0005] Therefore, there is an urgent need to develop an electrode structure and its processing method that does not require an auxiliary medium, can maintain the integrity of the porous framework structure, and can improve the wettability of deep electrolytes through structural and surface modification, so as to promote the practical application of thick electrodes in high energy density energy storage devices. Summary of the Invention

[0006] One of the objectives of this invention is to provide a thick porous carbon material with a hydrophilic vertical microchannel array. While maintaining the stability of the overall hydrophobic framework structure, this material has hydrophilic vertical channel inner walls. By constructing low-torsion high-speed ion channels and the synergistic effect of surface chemical modification, the problems of kinetic hysteresis and wetting difficulties in thick electrodes can be solved.

[0007] To achieve the above objectives, the present invention employs the following technical solution: a thick-layer porous carbon material with a hydrophilic vertical microchannel array, comprising: An integrated porous carbon framework matrix, wherein the thickness of the porous carbon framework matrix is ​​200 μm to 2000 μm; A vertical microchannel array, which penetrates the upper and lower surfaces of the porous carbon framework matrix; The inner wall surface of the vertical microchannel has a hydrophilic modification layer with a water contact angle of less than 90°; the porous carbon skeleton matrix is ​​hydrophobic in the bulk region away from the vertical microchannel, with a water contact angle of greater than 100°.

[0008] Further improvements to thick-layer porous carbon materials with hydrophilic vertical microchannel arrays: Preferably, the diameter of the vertical microchannel is 60 μm to 200 μm, the center-to-center distance between adjacent vertical microchannels is 200 μm to 400 μm, and the array design of the vertical microchannel is a square array, a hexagonal array, or a concentric circle array.

[0009] Preferably, the porous carbon framework matrix is ​​selected from any one of laser-induced graphene (LIG) foam, activated carbon calendered thick film, carbon aerogel, or porous carbon composite material.

[0010] A second objective of this invention is to provide a method for preparing a thick-layer porous carbon material with a hydrophilic vertical microchannel array as described in any one of the above-mentioned methods. This method utilizes the dry processing characteristics of short-wavelength lasers to solve the problem of porous structure collapse caused by existing wet processing methods. The method includes the following steps: (1) Preparation of thick porous carbon substrate: The carbon precursor is prepared into a solution and coated on the substrate, dried to form a precursor film, and then laser-induced carbonization is performed; the “coating-drying-carbonization” steps are repeated multiple times to obtain an integrated thick porous carbon skeleton of the target thickness. (2) Construction of vertical microchannel array: In a gas phase environment, the thick porous carbon skeleton is directly scanned and ablated by a pulsed laser beam according to a preset array trajectory, and part of the material is physically removed to form a vertical channel that runs through its upper and lower surfaces; during the laser processing, due to the thermal localization effect of the porous skeleton, an oxidation reaction is induced at the edge of the inner wall of the channel while the channel is formed, thereby obtaining a hydrophilic modified layer limited to the edge of the vertical microchannel within a range of 1 μm to 20 μm on the inner wall of the channel, forming a thick porous carbon material with a wettability difference structure.

[0011] Further improvements were made to the preparation method of thick-layer porous carbon materials with hydrophilic vertical microchannel arrays: Preferably, in step (1), the carbon precursor is one or more of polyethersulfone, polyimide, phenolic resin, polyacrylonitrile, lignin, and pitch; and the solvent of the carbon precursor solution is N,N-dimethylacetamide, N-methylpyrrolidone, or dimethyl sulfoxide.

[0012] Preferably, in step (1), the coating is applied by blade coating, spin coating, screen printing or spraying; the thickness of the single-layer wet film coating is 50~500 μm; the substrate is a polyimide film, a polyetheretherketone film, a copper foil or a nickel foil.

[0013] Preferably, in step (1), the laser-induced carbonization uses a CO2 laser with a wavelength of 10.6 μm, a laser power of 5~20 W, and a scanning speed of 50~300 mm / s.

[0014] Preferably, the surface loading of the integrated thick porous carbon framework active material obtained in step (1) is 5 mg / cm² to 30 mg / cm².

[0015] Preferably, in step (2), the gas phase environment is an air environment; the pulsed laser beam is selected from nanosecond pulsed lasers or femtosecond lasers with wavelengths from 300 nm to 1100 nm, preferably with a wavelength of 1064 nm; the processing parameters are: power 20~40 W, scanning speed 400~600 mm / s, frequency 15~25 kHz, the scanning trajectory is one of square, hexagon or concentric circle, the target aperture is 60 μm to 100 μm, and the center distance between adjacent channels is 200 μm to 400 μm.

[0016] The third objective of this invention is to provide an application of the thick porous carbon material with hydrophilic vertical microchannel array described in any of the above claims in an electrochemical energy storage device, wherein the electrochemical energy storage device is a zinc ion hybrid capacitor, with the thick porous carbon material as the positive electrode, zinc foil or zinc-plated material as the negative electrode, and zinc sulfate aqueous solution as the electrolyte.

[0017] The advantages of this invention compared to the prior art are as follows: (1) This invention provides a thick porous carbon material with a hydrophilic vertical microchannel array, which has the following advantages based on its special composition and structure: The geometry optimization for "decoupling transport distance" involves a vertical channel array acting as an "ion highway" running through the electrode. This decouples the long diffusion path along the electrode thickness (longitudinal, ~500 μm) into a short-range radial diffusion (e.g., ~110 μm) from the channel wall towards the surrounding porous framework. This significantly reduces the tortuosity of ion transport, eliminates the "dead volume" deep within the electrode, and allows for full utilization of the active material. Tests show that this structure enables the electrode to achieve excellent rate performance even at high areal loading.

[0018] The surface chemical design driven by gradient wetting involves in-situ modification to create a structure with differential wetting properties between the hydrophilic channel wall and the hydrophobic framework. The contact angle of the inner wall of the vertical channel decreases from ~102° to ~68°, becoming hydrophilic. This wetting gradient generates a strong capillary driving force inside the electrode, making the vertical channel a highly efficient "liquid wick" that actively and rapidly draws the electrolyte into the deep layers of the electrode, achieving uniform and thorough wetting of the electrolyte and solving the "wetting difficulty" problem of thick electrodes.

[0019] (2) The preparation method of the present invention is a highly integrated and streamlined overall technical solution. Its core lies in utilizing the unique principle of the interaction between laser and porous materials to achieve "structural processing" and "surface modification" in one step.

[0020] Preparation of thick-layer porous carbon substrate: The carbon precursor is prepared into a solution and uniformly coated onto the substrate, dried to form a precursor film, and then laser-induced carbonization is performed. The "coating-drying-carbonization" steps can be repeated multiple times as needed to obtain an integrated thick-layer porous carbon framework of the target thickness. Laser-induced carbonization uses a CO2 laser, and the parameters are set to ensure that the precursor is fully converted into a porous graphene framework. Construction of the vertical microchannel array: In an air environment, a pulsed laser beam is used to directly scan and ablate the thick porous carbon skeleton according to a preset array trajectory, physically removing part of the material to form a vertical channel that runs through the upper and lower surfaces of the electrode. This step adopts a dielectric-free dry processing method, without introducing any liquid auxiliary medium or solid sacrificial layer. The thermal diffusion is limited by the phonon scattering limitation characteristics of porous materials. The process is carried out in an air environment, and no solvent cleaning step is required after laser processing.

[0021] In-situ surface modification: Utilizing the thermal localization effect during laser processing and the phonon scattering effect to limit heat diffusion, the heat-affected zone (HAZ) generated by laser processing is confined to a 10 μm range at the edge of the vertical microchannel. Simultaneously, oxidation reactions are induced at the inner wall edge of the channel, resulting in a thick-layer porous carbon material with a wettability difference structure. Testing showed that the ID / IG ratio in the Raman spectrum of the inner wall edge region of the vertical microchannel is higher than that of the porous carbon framework matrix region, with an increase of at least 10%. This indicates an increased defect site density in the inner wall edge region. The wettability difference structure formed between the hydrophilic modification layer and the bulk region promotes the radial penetration of the electrolyte into the deeper layers of the electrode.

[0022] (3) This invention utilizes a thick porous carbon material with a hydrophilic vertical microchannel array as an electrode in electrochemical energy storage devices. Specifically, when applied to a zinc-ion hybrid capacitor, zinc foil or zinc-plated material is used as the negative electrode, and zinc sulfate aqueous solution is used as the electrolyte. Based on the special structure of this material, the zinc-ion hybrid capacitor assembled with this material as the positive electrode exhibits excellent performance. The vertical channel, as a highly efficient dual-function network for ion transport and electrolyte transport, ensures that the device achieves both high energy density and high power density under high areal loading, breaking through the performance bottleneck of traditional porous carbon thick electrodes. Attached Figure Description

[0023] Figure 1 This is a surface SEM image of LIG-PI-100-P80 obtained in Example 1.

[0024] Figure 2 yes Figure 1 A magnified partial SEM image of the surface of LIG-PI-100-P80 obtained in Example 1.

[0025] Figure 3 This is a cross-sectional view of LIG-PI-100-P80 prepared in Example 1.

[0026] Figure 4 This is a surface SEM image of LIG-PI-100-P60 obtained in Example 2.

[0027] Figure 5 yes Figure 4 A magnified view of the surface SEM image of LIG-PI-100-P60 obtained in Example 2.

[0028] Figure 6 This is a cross-sectional view of LIG-PI-100-P60 obtained in Example 2.

[0029] Figure 7This is a surface SEM image of LIG-PI-100-P100 obtained in Example 3.

[0030] Figure 8 yes Figure 7 A magnified view of the surface SEM image of LIG-PI-100-P100 obtained in Example 3.

[0031] Figure 9 This is a cross-sectional view of LIG-PI-100-P100 prepared in Example 3.

[0032] Figure 10 This is a surface SEM image of LIG-PI-100 obtained in Comparative Example 1.

[0033] Figure 11 yes Figure 10 A magnified view of a portion of the surface SEM image of LIG-PI-100 obtained in Comparative Example 1.

[0034] Figure 12 This is a cross-sectional view of LIG-PI-100 prepared in Comparative Example 1.

[0035] Figure 13 The above figures show the surface water contact angle test results of the thick porous carbon materials prepared in the embodiments and comparative examples of the present invention; where a, b, c, and d correspond to Comparative Example 1 (LIG-PI-100), Example 2 (LIG-PI-100-P60), Example 1 (LIG-PI-100-P80), and Example 3 (LIG-PI-100-P100), respectively.

[0036] Figure 14 The galvanostatic charge-discharge (GCD) curves of the three-electrode system using LIG-PI-100-P80 prepared in Example 1 as the working electrode at different current densities are shown.

[0037] Figure 15 The galvanostatic charge-discharge (GCD) curves of the three-electrode system using LIG-PI-100-P60 prepared in Example 2 as the working electrode are shown at different current densities.

[0038] Figure 16 The galvanostatic charge-discharge (GCD) curves of the three-electrode system using LIG-PI-100-P100 prepared in Example 3 as the working electrode are shown at different current densities.

[0039] Figure 17 The galvanostatic charge-discharge (GCD) curves of the three-electrode system with LIG-PI-100 as the working electrode prepared in Comparative Example 1 at different current densities are shown.

[0040] Figure 18The GCD curves of a two-electrode energy storage device using LIG-PI-100-P80 prepared in Example 1 as the positive electrode are shown at different current densities.

[0041] Figure 19 The GCD curves of the two-electrode energy storage device with LIG-PI-100 as the positive electrode prepared in Comparative Example 1 under different current densities are shown. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0043] Example 1 This embodiment provides a method for preparing a thick-layer porous carbon material with a hydrophilic vertical microchannel array, specifically including the following steps: Polyethersulfone (PES) was selected as the carbon precursor, and N,N-dimethylacetamide (DMAC) was used as the solvent to prepare a homogeneous and transparent solution with a concentration of 20 wt%. The carbon precursor solution was prepared and coated onto the substrate using a blade coating method. The substrate was a commercial polyimide (PI) film, and the thickness of the single-layer wet film was controlled at 100 μm. After drying, the precursor film was formed. The dried precursor film was laser-induced carbonization using a CO2 laser with a wavelength of 10.6 μm, a laser power of 8.0 W, a scanning speed of 100 mm / s, and a line spacing of 0.1 mm. The "coating-drying-carbonization" steps were repeated 5 times to obtain an integrated thick porous carbon framework matrix (denoted as LIG-PI-100) with a thickness of approximately 500 μm. The surface of the matrix is ​​hydrophobic with a water contact angle of approximately 102°.

[0044] (2) Construction and hydrophilic modification of vertical microchannel arrays: In a room temperature air environment, the thick porous carbon skeleton prepared in step (1) was directly arrayed and scanned ablated using an Nd:YAG pulsed laser (wavelength 1064 nm). The processing parameters were: laser power 30 W, scanning speed 500 mm / s, frequency 20 kHz; the array design was set as follows: the scanning trajectory was circular, the target aperture was 80 μm, and the pitch between adjacent channels was 300 μm; physical removal of some material formed a vertical microchannel array that penetrated the upper and lower surfaces.

[0045] During laser processing, due to the thermal localization effect of the porous framework, an in-situ oxidation reaction occurs at the edge of the channel inner wall, forming a hydrophilic modified layer limited to a range of 10 μm at the edge of the vertical microchannel, ultimately obtaining a thick porous carbon material with a wettability differential structure (denoted as LIG-PI-100-P80).

[0046] Tests showed that the actual channel diameter of LIG-PI-100-P80 was approximately 81 μm, and the surface loading of active material was approximately 10.21 mg / cm².

[0047] Example 2 This embodiment provides a method for preparing a thick porous carbon material with a hydrophilic vertical microchannel array. The specific steps are the same as in Embodiment 1, except that in step (2), the target pore size of the laser scanning trajectory is set to 60 μm, and a thick porous carbon material with a wettability difference structure (denoted as LIG-PI-100-P60) is finally obtained.

[0048] Tests showed that the actual channel diameter of LIG-PI-100-P60 is approximately 62 μm, and the surface loading of active material is approximately 10.54 mg / cm².

[0049] Example 3 The preparation method of thick porous carbon material with hydrophilic vertical microchannel array is as follows: the specific steps are the same as in Example 1, except that in step (2), the target pore size of the laser scanning trajectory is set to 100 μm, and finally a thick porous carbon material with wettability difference structure (denoted as LIG-PI-100-P100) is obtained.

[0050] Tests showed that the actual channel diameter of LIG-PI-100-P100 is approximately 105 μm, and the surface loading of active material is approximately 9.46 mg / cm².

[0051] Example 4 This embodiment provides a method for preparing a thick-layer porous carbon material with a hydrophilic vertical microchannel array, specifically including the following steps: (1) Preparation of thick porous carbon substrate: Polyimide (PI) was selected as the carbon precursor, and N-methylpyrrolidone (NMP) was used as the solvent to prepare a homogeneous and transparent solution with a concentration of 20 wt%. The carbon precursor solution was coated onto a substrate, which was a copper foil, using a spin coating method. The thickness of the single-layer wet film was controlled at 50 μm, and the film was dried to form a precursor film. The dried precursor film was laser-induced carbonization using a CO2 laser with a wavelength of 10.6 μm, a laser power of 5.0 W, a scanning speed of 50 mm / s, and a line spacing of 0.1 mm. The coating-drying-carbonization process was repeated 6 times to obtain an integrated thick porous carbon framework matrix (denoted as LIG-Cu-50) with a thickness of approximately 300 μm and an active material surface loading of approximately 7.4 mg / cm². The matrix surface is hydrophobic with a water contact angle of approximately 108°.

[0052] (2) Construction and hydrophilic modification of vertical microchannel arrays: In a room temperature air environment, the thick porous carbon skeleton prepared in step (1) was directly arrayed and scanned ablated using an Nd:YAG pulsed laser (wavelength 355 nm). The processing parameters were: laser power 20 W, scanning speed 400 mm / s, frequency 15 kHz; the array design was set as follows: the scanning trajectory was square, the target aperture was 60 μm, and the pitch between adjacent channels was 200 μm; some material was physically removed to form a vertical microchannel array that runs through the upper and lower surfaces.

[0053] During laser processing, due to the thermal localization effect of the porous framework, an in-situ oxidation reaction occurs at the edge of the channel inner wall, forming a hydrophilic modified layer limited to a range of 10 μm at the edge of the vertical microchannel, ultimately obtaining a thick porous carbon material with a wettability differential structure (denoted as LIG-Cu-50-P60).

[0054] The actual channel diameter of LIG-Cu-50-P60 was found to be approximately 63 μm, and the surface loading of active material was approximately 5.8 mg / cm².

[0055] Example 5 This embodiment provides a method for preparing a thick-layer porous carbon material with a hydrophilic vertical microchannel array, specifically including the following steps: (1) Preparation of thick porous carbon substrate: Phenolic resin was selected as the carbon precursor, and dimethyl sulfoxide (DMSO) was used as the solvent to prepare a homogeneous and transparent solution with a concentration of 20 wt%. The carbon precursor solution was coated onto a substrate, which was a nickel foil, by a spraying method. The thickness of the single-layer wet film was controlled at 500 μm, and the film was dried to form a precursor film. The dried precursor film was laser-induced carbonization using a CO2 laser with a wavelength of 10.6 μm, a laser power of 20.0 W, a scanning speed of 300 mm / s, and a line spacing of 0.1 mm. The "coating-drying-carbonization" steps were repeated twice to obtain an integrated thick porous carbon framework matrix (denoted as LIG-Ni-500) with a thickness of approximately 1000 μm and an active material surface loading of approximately 20 mg / cm². The matrix surface is hydrophobic with a water contact angle of approximately 95°.

[0056] (2) Construction and hydrophilic modification of vertical microchannel arrays: In a room temperature air environment, a femtosecond laser (wavelength 1100 nm) was used to perform direct array scanning ablation on the thick porous carbon skeleton prepared in step (1). The processing parameters were: laser power 40 W, scanning speed 600 mm / s, frequency 25 kHz; the array design was set as follows: the scanning trajectory was hexagonal, the target aperture was 100 μm, and the pitch between adjacent channels was 400 μm; physical removal of some material formed a vertical microchannel array that penetrated the upper and lower surfaces.

[0057] During laser processing, due to the thermal localization effect of the porous framework, an in-situ oxidation reaction occurs at the edge of the channel inner wall, forming a hydrophilic modified layer limited to a range of 10 μm at the edge of the vertical microchannel, ultimately obtaining a thick porous carbon material with a wettability differential structure (denoted as LIG-Ni-500-P100).

[0058] Tests showed that the actual channel diameter of LIG-Ni-500-P100 is approximately 103 μm, and the surface loading of active material is approximately 23.5 mg / cm².

[0059] Comparative Example 1 This embodiment provides a method for preparing a thick porous carbon material. The specific steps are the same as in Example 1, except that the 1064 nm laser drilling process in step (2) is not performed. Finally, a thick porous carbon material (denoted as LIG-PI-100) is obtained.

[0060] Tests showed that the surface load of LIG-PI-100 was approximately 11.08 mg / cm².

[0061] Performance testing (1) Morphological and structural analysis: Figure 1 This is a surface SEM image of LIG-PI-100-P80 obtained in Example 1. (From...) Figure 1 As can be seen, the electrode surface has a highly ordered and periodically arranged array of circular microchannels, with a center-to-center spacing of approximately 300 μm between adjacent channels. Measurements show that the actual channel diameter is approximately 81 μm, which highly matches the preset 80 μm laser processing trajectory, demonstrating extremely high processing precision. Figure 2 yes Figure 1 A magnified view of a portion of the image. (From...) Figure 2 It can be seen that the channel boundaries formed by laser processing are clear and well-defined, and no obvious dense recast layer was observed at the channel edges and in the surrounding area. The graphene framework around the channel retains its original three-dimensional hierarchical porous structure, which confirms that the thermal localization effect of the porous framework effectively protects the matrix structure. Figure 3 This is a cross-sectional view of the electrode prepared in Example 1. (From...) Figure 3 As can be seen, the electrode has a significant thickness, with a measured total thickness of approximately 500 μm. This thick-layer structure provides ample volume space for the high loading of active material (approximately 10.21 mg / cm²). From the cross-sectional morphology, the porous carbon framework is continuously stacked along the vertical direction, exhibiting a uniform structure without obvious delamination or fracture, demonstrating the structural stability of the layer-by-layer assembly process combined with laser post-processing.

[0062] Figure 4 This is a surface SEM image of LIG-PI-100-P60 obtained in Example 2. As shown in the figure, when the laser scanning trajectory is set to 60 μm, a regularly arranged array of microchannels is also formed on the electrode surface. Figure 5 yes Figure 4 A magnified view of a portion of the image. (From...) Figure 5 It can be seen that the actual diameter of the channel formed is about 62 μm. Although the aperture is small, the structure is complete, there is no blockage at the channel opening, and the edges remain clean. Figure 6 This is a cross-sectional view of the electrode prepared in Example 2. (From...) Figure 6 It can be seen that the electrode still maintains a thickness of about 500 μm, indicating that the laser drilling process did not cause compression or collapse of the overall thickness of the electrode, thus ensuring a sufficient total number of active sites.

[0063] Figure 7 This is a surface SEM image of LIG-PI-100-P100 obtained in Example 3. As shown in the figure, with the adjustment of laser processing parameters, a microchannel array with large apertures was formed on the electrode surface. Figure 8 yes Figure 7 A magnified view of a portion of the image. (From...) Figure 8 It can be seen that the actual channel diameter is about 105 μm, and the channel opening is very wide. Figure 9 This is a cross-sectional view of the electrode prepared in Example 3. Figure 9 As can be seen, the electrode cross-section exhibits a thick and porous morphology with good thickness uniformity (~500 μm). Although the large-diameter processing removed some material, the overall electrode framework still maintained good mechanical support and did not collapse.

[0064] Figure 10 This is a surface SEM image of LIG-PI-100 obtained in Comparative Example 1. Figure 10 It can be seen that the electrode surface without laser drilling has a continuous and dense appearance, lacking macroscopic electrolyte inlets. Figure 11 yes Figure 10 A magnified view of a portion of the image. (From...) Figure 11 It can be seen that the electrode is composed of randomly oriented and interconnected graphene sheets stacked together, forming a typical highly tortuous three-dimensional hierarchical porous structure. Figure 12This is a cross-sectional view of the electrode prepared in Comparative Example 1. (From...) Figure 12 As can be seen, the electrode also has a thickness of approximately 500 μm, and its interior is filled with disordered stacked graphene sheets. This dense porosity at such a thickness, while providing the maximum loading capacity, also clearly reflects the physical barrier that makes it difficult for the electrolyte to penetrate deeply within it.

[0065] (2) Wettability analysis: Figure 13 The images show the surface water contact angle test results of the thick porous carbon materials prepared in Examples 1-3 and Comparative Example 1 of this invention; where a, b, c, and d correspond to Comparative Example 1 (LIG-PI-100), Example 2 (LIG-PI-100-P60), Example 1 (LIG-PI-100-P80), and Example 3 (LIG-PI-100-P100), respectively.

[0066] contrast Figure 13 The overall water contact angle tests of electrodes prepared in different embodiments and comparative examples are shown to be compared. The results show that the construction of the laser microchannel array significantly improves the overall wettability of the thick electrode. Comparative Example 1 (LIG-PI-100) exhibits obvious hydrophobicity of about 102° due to the inherent low surface energy of the graphene framework and the "air cushion" effect formed by the micro-nano structure, which hinders the effective contact of the electrolyte. However, after the introduction of the laser microchannel, the electrode surface rapidly changes from hydrophobic to hydrophilic. As the channel aperture increases from 60 μm (Example 2) to 80 μm (Example 1) and finally reaches 100 μm (Example 3), its overall contact angle shows a gradient change trend from 80°, 75° to 68°. This overall hydrophilic transformation is attributed to the synergistic effect of "geometry-surface chemistry": the high energy density of the laser beam not only increases the macroscopic geometric roughness conforming to the Wenzel model by removing material, but also introduces abundant edge defects and oxygen-containing functional groups in situ in the arrayed region (as shown by Raman spectroscopy), thereby significantly improving the overall polarity of the electrode surface; the larger the pore size, the stronger this synergistic modification effect, and the resulting hydrophilic surface provides a key physicochemical basis for eliminating the deep "dead volume" of thick electrodes and achieving rapid and complete electrolyte wetting.

[0067] (3) Assemble the three-electrode system and perform electrochemical performance testing: Thick-layer porous carbon materials prepared in Examples 1, 2, 3, and Comparative Example 1 were used as working electrodes, platinum sheets as counter electrodes, Ag / AgCl electrodes as reference electrodes, and zinc sulfate solution (1 mol / L) as electrolytes to assemble three-electrode systems. Constant current charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) tests were performed on the above three-electrode systems on an electrochemical workstation.

[0068] Figure 14 The images show the galvanostatic charge-discharge (GCD) curves of a three-electrode system using the thick porous carbon material prepared in Example 1 as the working electrode at different current densities. Figure 14 As can be seen, within a wide current density range of 1.0–20.0 mA / cm², the GCD curve exhibits a nearly symmetrical isosceles triangle shape, with a flat voltage plateau and minimal initial voltage drop (IR drop). Based on discharge time calculations, even at a high current density of 20 mA / cm², the electrode's areal capacitance remains as high as 434.0 mF / cm², representing a capacitance retention of 62.9% compared to the initial capacitance at lower current densities. This demonstrates that the 80 μm vertical microchannel array effectively decouples the limitations of ion transport distance and electrode thickness, successfully activating deep active sites.

[0069] Figure 15 The GCD curves of a three-electrode system using the thick porous carbon material prepared in Example 2 as the working electrode are shown at different current densities. Figure 15 As can be seen, the electrode exhibits good capacitive behavior with a regular curve shape. However, compared to Example 1, due to its smaller channel aperture, the instantaneous electrolyte infusion flux is somewhat limited at high rates, resulting in a capacity retention rate of 51.9% at high current densities, which is lower than that of Example 1.

[0070] Figure 16 The GCD curves of the three-electrode system using the thick porous carbon material prepared in Example 3 as the working electrode are shown at different current densities. Figure 16 As can be seen, the electrode exhibits excellent kinetic characteristics within the test range, and the charge-discharge process is highly reversible. However, due to the removal of a significant amount of active material by the large 100 μm pore size (area loading reduced to approximately 9.46 mg / cm²), its absolute areal capacitance is slightly lower than that of Example 1. This indicates that the 80 μm pore size of Example 1 achieves an optimal balance between "active material loading" and "ion transport efficiency".

[0071] Figure 17 The GCD curves of the three-electrode system using the thick porous carbon material prepared in Comparative Example 1 as the working electrode are shown at different current densities. Figure 17 It can be seen that at low current density (1.0 mA / cm²), the discharge time is the longest due to the highest load. However, as the current density increases, the GCD curve shows significant compression and voltage drop. At 20 mA / cm², the capacitance retention is only 34.6%, significantly lower than in Example 1. This indicates that without the introduction of a vertical channel structure, there is severe diffusion restriction inside the dense thick electrode, causing the deep material to become a "dead volume" that cannot participate in the reaction.

[0072] (4) Assemble the two-electrode energy storage device and conduct electrochemical performance testing: Using the thick porous carbon materials prepared in Example 1 and Comparative Example 1 as positive electrodes, commercial zinc foil as negative electrodes, and zinc sulfate solution (1 mol / L) as electrolyte, two-electrode energy storage devices were constructed. Constant current charge-discharge tests were performed on the two-electrode energy storage devices on an electrochemical workstation.

[0073] Figure 18 The image shows the GCD curves of a two-electrode energy storage device using the thick porous carbon material (LIG-PI-100-P80) prepared in Example 1 as the positive electrode at different current densities. Figure 18 As can be seen, within a wide test range of 1 mA / cm² to 20 mA / cm², the charge-discharge curves of the device maintain a highly symmetrical quasi-isosceles triangle shape, and the voltage drop (IR drop) during charge-discharge switching is extremely small. This indicates that the device has excellent electrochemical reversibility and extremely low internal equivalent series resistance. Based on the discharge time, at a current density of 1 mA / cm², the areal capacitance of the device is 469.2 mF / cm²; even with a significant increase in current density to 20 mA / cm², the device can still output a high specific capacitance of 260.0 mF / cm², corresponding to a capacitance retention rate as high as 55.4%. Therefore, even under high current surges, the vertical microchannel array described in Example 1 can effectively decouple ion transport from the limitations of electrode thickness, endowing the device with excellent rate performance and thickness utilization.

[0074] Under the same conditions, thick-layer porous carbon materials prepared in Examples 4 and 5 were used as positive electrodes, commercial zinc foil as negative electrodes, and zinc sulfate solution (1 mol / L) as electrolyte to construct two-electrode energy storage devices. Constant current charge-discharge tests were performed on the two-electrode energy storage devices on an electrochemical workstation. Based on the discharge time, at a current density of 1 mA / cm², the areal specific capacitance of the device assembled using the thick-layer porous carbon material of Example 4 was 290.8 mF / cm²; even with a significant increase in current density to 20 mA / cm², the device still output a high specific capacitance of 171.5 mF / cm², corresponding to a capacitance retention rate as high as 58.9%. Based on the discharge time, at a current density of 1 mA / cm², the areal specific capacitance of the device assembled using the thick-layer porous carbon material of Example 5 was 938.8 mF / cm²; even with a significant increase in current density to 20 mA / cm², the device still output a high specific capacitance of 441.2 mF / cm², corresponding to a capacitance retention rate as high as 46.9%.

[0075] Figure 19The GCD curves of a two-electrode energy storage device using the thick porous carbon material (LIG-PI-100) prepared in Comparative Example 1 as the positive electrode are shown at different current densities. Figure 19 As can be seen, at a low current density of 1 mA / cm², thanks to the high active material loading (without pore loss), it exhibits a maximum initial capacitance of 507.2 mF / cm². However, once the current density increases to 20 mA / cm², the curve becomes severely distorted, the discharge time shortens drastically, and a significant ohmic polarization phenomenon is observed. At this point, its areal capacitance drops sharply to 154.0 mF / cm², with a capacitance retention of only 30.4%. This significant performance degradation (from 507.2 to 154) further confirms that, without the introduction of vertical channels, there is a severe diffusion barrier inside the dense, thick electrode, preventing the effective utilization of deep active sites at high rates and creating a kinetically "dead volume."

[0076] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

[0077] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A thick-layer porous carbon material with a hydrophilic vertical microchannel array, characterized in that, include: An integrated porous carbon framework matrix, wherein the thickness of the porous carbon framework matrix is ​​200 μm to 2000 μm; A vertical microchannel array, which penetrates the upper and lower surfaces of the porous carbon framework matrix; The inner wall surface of the vertical microchannel has a hydrophilic modification layer with a water contact angle of less than 90°; the porous carbon skeleton matrix is ​​hydrophobic in the bulk region away from the vertical microchannel, with a water contact angle of greater than 100°.

2. The thick-layer porous carbon material with a hydrophilic vertical microchannel array according to claim 1, characterized in that, The diameter of the vertical microchannel is 60 μm to 200 μm, the center-to-center distance between adjacent vertical microchannels is 200 μm to 400 μm, and the array design of the vertical microchannel is a square array, a hexagonal array, or a concentric circle array.

3. The thick-layer porous carbon material with a hydrophilic vertical microchannel array according to claim 1, characterized in that, The porous carbon framework matrix is ​​selected from any one of laser-induced graphene foam, activated carbon calendered thick film, carbon aerogel, or porous carbon composite material.

4. A method for preparing a thick-layer porous carbon material with a hydrophilic vertical microchannel array as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Preparation of thick porous carbon substrate: The carbon precursor is prepared into a solution and coated on the substrate, dried to form a precursor film, and then laser-induced carbonization is performed; the "coating-drying-carbonization" steps are repeated multiple times to obtain an integrated thick porous carbon skeleton of the target thickness. (2) Construction of vertical microchannel array: In a gas phase environment, the thick porous carbon skeleton is directly scanned and ablated by a pulsed laser beam according to a preset array trajectory, and part of the material is physically removed to form a vertical channel that runs through its upper and lower surfaces; during the laser processing, due to the thermal localization effect of the porous skeleton, an oxidation reaction is induced at the edge of the inner wall of the channel while the channel is formed, thereby obtaining a hydrophilic modified layer limited to the edge of the vertical microchannel within a range of 1 μm to 20 μm on the inner wall of the channel, forming a thick porous carbon material with a wettability difference structure.

5. The method for preparing thick-layer porous carbon material with a hydrophilic vertical microchannel array according to claim 4, characterized in that, In step (1), the carbon precursor is one or more of polyethersulfone, polyimide, phenolic resin, polyacrylonitrile, lignin, and pitch; the solvent of the carbon precursor solution is N,N-dimethylacetamide, N-methylpyrrolidone, or dimethyl sulfoxide.

6. The method for preparing thick-layer porous carbon material with a hydrophilic vertical microchannel array according to claim 4, characterized in that, In step (1), the coating is applied by blade coating, spin coating, screen printing or spraying; the thickness of the single-layer wet film coating is 50~500 μm; the substrate is a polyimide film, a polyetheretherketone film, a copper foil or a nickel foil.

7. The method for preparing thick-layer porous carbon material with a hydrophilic vertical microchannel array according to claim 4, characterized in that, In step (1), the laser-induced carbonization uses a CO2 laser with a wavelength of 10.6 μm, a laser power of 5~20W, and a scanning speed of 50~300 mm / s.

8. The method for preparing thick-layer porous carbon material with a hydrophilic vertical microchannel array according to claim 4, characterized in that, The surface loading of the integrated thick porous carbon framework active material obtained in step (1) is 5 mg / cm² to 30 mg / cm².

9. The method for preparing a thick-layer porous carbon material with a hydrophilic vertical microchannel array according to claim 4, characterized in that, In step (2), the gas phase environment is an air environment; the pulsed laser beam is selected from nanosecond pulsed lasers or femtosecond lasers with wavelengths from 300 nm to 1100 nm, preferably with a wavelength of 1064 nm; the processing parameters are: power 20~40 W, scanning speed 400~600 mm / s, frequency 15~25 kHz, the scanning trajectory is one of square, hexagon or concentric circle, the target aperture is 60 μm to 100 μm, and the center distance between adjacent channels is 200 μm to 400 μm.

10. The application of a thick-layer porous carbon material with a hydrophilic vertical microchannel array as described in any one of claims 1 to 3 in an electrochemical energy storage device, characterized in that, The electrochemical energy storage device is a zinc-ion hybrid capacitor, with a thick layer of porous carbon material as the positive electrode, zinc foil or zinc-plated material as the negative electrode, and zinc sulfate aqueous solution as the electrolyte.

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