Self-healing hydrogel material, preparation method thereof and hydrogen storage tank thermal management module

Abstract

This application relates to the field of thermal management technology for hydrogen storage tanks, and in particular provides a self-healing hydrogel material, its preparation method, and a thermal management module for hydrogen storage tanks. The self-healing hydrogel material comprises a polymer matrix, a thermally conductive filler, a dynamic crosslinking agent, and a solvent. The dynamic crosslinking agent can dynamically crosslink with hydrogen bonds, thereby giving the self-healing hydrogel material excellent self-healing capabilities. Furthermore, the thermally conductive filler, added to the polymer matrix, can form a uniformly distributed three-dimensional network with the polymer matrix, reducing interfacial thermal resistance, improving the overall stability of the material, and simultaneously enhancing its thermodynamic and mechanical properties. The self-healing hydrogel material of this application can adaptively fill or repair microcracks at the interface, maintain the heat conduction path, and possesses strong self-healing capabilities and a long service life.

Description

Technical Field

[0001] This application relates to the field of thermal management technology for hydrogen storage tanks, and in particular to a self-healing hydrogel material, its preparation method, and a thermal management module for hydrogen storage tanks. Background Technology

[0002] Solid-state hydrogen storage technology has significant application value in the field of hydrogen energy storage due to its high volumetric hydrogen storage density (more than 1.5 times that of liquid hydrogen storage) and inherent safety (no high-pressure container required). However, solid-state hydrogen storage materials (such as MgH2, LaNi5, etc.) undergo significant volume changes (typically 20%-30%) during hydrogen absorption and desorption, leading to the following core problems: 1. Deterioration of interfacial thermal resistance: The contact interface between the hydrogen storage material and the heat exchange structure (such as phase change materials, metal heat-conducting plates) develops microcracks or air gaps due to repeated expansion / contraction, resulting in a decrease in thermal conductivity of more than 50%; 2. Decrease in thermal management efficiency: The heat transfer medium cannot adaptively compensate for volume changes, causing the hydrogen absorption and desorption rate to decrease with the increase of cycle number.

[0003] In existing technologies, silicone grease and metal pads are commonly used as thermal conductive media. These traditional thermal conductive media tend to crack or peel off after cycling, cannot self-repair, and their thermal management efficiency decreases significantly after long-term cycling.

[0004] Therefore, existing solid hydrogen storage materials suffer from weak self-healing capabilities and insufficient long-term stability. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a self-healing hydrogel material, its preparation method and a thermal management module for a hydrogen storage tank, aiming to solve the problems of weak self-healing ability and insufficient long-term stability of existing solid hydrogen storage materials.

[0006] The technical solution adopted by this application to solve the technical problem is as follows: On the one hand, this application provides a self-healing hydrogel material, comprising: a polymer matrix, a thermally conductive filler, a dynamic crosslinking agent, and a solvent; The polymer matrix is ​​at least one of polyvinyl alcohol, polyacrylamide, and N-isopropylacrylamide, and the polymer matrix accounts for 5-15 wt% of the self-healing hydrogel material. The thermally conductive filler is plasma-treated graphene nanosheets or carbon nanotubes, and the thermally conductive filler accounts for 5-8% of the volume fraction of the self-healing hydrogel material. The dynamic crosslinking agent is at least one of iron-containing crosslinking agents and calcium-containing crosslinking agents, and the molar fraction of the dynamic crosslinking agent in the polymer matrix is ​​1-5 mol%. The solvent accounts for 0.1-50 wt% of the self-healing hydrogel material.

[0007] Optionally, the plasma-treated graphene nanosheets are obtained by argon plasma irradiation.

[0008] Optionally, the iron-containing crosslinking agent is at least one of the following: a mixture of soluble iron salt and acrylic polymer, a complex obtained by reacting soluble iron salt and acrylic polymer, a mixture of soluble iron salt and catechol, and a mixture of soluble iron salt and citric acid; the calcium-containing crosslinking agent is at least one of the following: a mixture of soluble calcium salt and sodium alginate, a mixture of soluble calcium salt and carboxymethyl cellulose, and a mixture of soluble calcium salt and polyacrylic acid.

[0009] Optionally, the molecular weight of the polyvinyl alcohol is (60,000-120,000); the polymer matrix is ​​a mixture of polyvinyl alcohol and N-isopropylacrylamide, wherein the mass ratio of the polyvinyl alcohol to the N-isopropylacrylamide is 5:(3-6).

[0010] Optionally, the self-healing hydrogel material further includes bismuth telluride, wherein the bismuth telluride accounts for 5-10 vol% of the volume of the self-healing hydrogel material.

[0011] This application also discloses a method for preparing the self-healing hydrogel material as described above, comprising the following steps: The polymer matrix is ​​completely dissolved in a solvent to obtain a matrix solution; The thermally conductive filler is added to the matrix solution, and a uniform dispersion is formed after ultrasonic treatment. The dynamic crosslinking agent was added to the uniform dispersion, and the mixture was stirred to obtain a mixture. The mixture was subjected to freeze-thaw cycles to obtain a self-healing hydrogel material.

[0012] Optionally, the freeze-thaw cycle is a gradient process: First, freeze at -20℃ to -10℃ for 2-6 hours; second, thaw at 5℃ to 15℃ for 1-4 hours; third, stabilize at 20℃ to 35℃ for 1-4 hours; fourth, repeat the operations from the first to the third step 2-6 times.

[0013] On the other hand, this application also provides a thermal management module for a hydrogen storage tank, comprising several processing units and a metal partition. Adjacent processing units are separated by the metal partition. Each processing unit includes a hydrogen storage layer, a phase change layer, and a metal perforated plate. The metal perforated plate is located between the hydrogen storage layer and the phase change layer. The metal perforated plate is provided with several holes, and the holes are filled with a self-healing coating. The material of the self-healing coating is the self-healing hydrogel material described above.

[0014] Optionally, the thickness of the hydrogen storage layer is 5-20 mm, the thickness of the phase change layer is 4-12 mm, and the thickness of the metal orifice plate is 0.5-1.5 mm.

[0015] Optionally, the pore diameter is 1.5-2 mm, the spacing between adjacent pores is 0.5-6 mm, and the pores are filled with at least 90% of the self-healing hydrogel material.

[0016] Optionally, the surface of the hydrogen storage layer is coated with the self-healing hydrogel material.

[0017] Compared with existing technologies, this application provides a self-healing hydrogel material, its preparation method, and a thermal management module for a hydrogen storage tank. The self-healing hydrogel material comprises a polymer matrix, a thermally conductive filler, a dynamic crosslinking agent, and a solvent. The dynamic crosslinking agent can dynamically crosslink with hydrogen bonds, thereby giving the self-healing hydrogel material excellent self-healing capabilities. Furthermore, the thermally conductive filler, added to the polymer matrix, can form a uniformly distributed three-dimensional network with the polymer matrix, reducing interfacial thermal resistance, improving the overall stability of the material, and simultaneously enhancing its thermodynamic and mechanical properties. The self-healing hydrogel material of this application can adaptively fill or repair microcracks at the interface, maintain the heat conduction path, and possesses strong self-healing capabilities and a long service life. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the thermal management module for the hydrogen storage tank provided in this application; Figure 2 yes Figure 1 A sectional view of AA; Figure 3 This is a schematic diagram of the processing unit in the thermal management module of the hydrogen storage tank provided in this application; Figure 4 This is a schematic diagram of the metal orifice plate in the thermal management module of the hydrogen storage tank provided in this application.

[0019] Explanation of reference numerals in the attached figures: 1. Outer wall; 2. Insulation layer; 3. Inlet and outlet; 4. Processing unit; 5. Metal perforated plate; 6. Metal partition; 41. Hydrogen storage layer; 42. Phase change layer; 51. Pores; 511. Self-healing coating. Detailed Implementation

[0020] The following describes in detail the test examples of this application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The test examples described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0021] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0023] The terms "parallel" and "perpendicular" do not mean that the components must be absolutely parallel or perpendicular, but rather that they can be slightly tilted. For example, "parallel" simply means that its direction is more parallel than "perpendicular," not that the structure must be completely parallel, but that it can be slightly tilted.

[0024] The terms "horizontal," "vertical," and "sag" do not imply that a component must be absolutely horizontal, vertical, or sagging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] A self-healing hydrogel material includes: a polymer matrix, a thermally conductive filler, a dynamic crosslinking agent, and a solvent.

[0027] The polymer matrix is ​​at least one of polyvinyl alcohol, polyacrylamide, and N-isopropylacrylamide, and the polymer matrix accounts for 5-15 wt% of the self-healing hydrogel material by mass. The thermally conductive filler is plasma-treated graphene nanosheets or carbon nanotubes, and the thermally conductive filler accounts for 5-8 vol% of the volume of the self-healing hydrogel material by volume. The dynamic crosslinking agent is at least one of iron-containing crosslinking agent and calcium-containing crosslinking agent, and the dynamic crosslinking agent accounts for 1-5 mol% of the molar fraction of the polymer matrix. The solvent accounts for 0.1-50 wt% of the self-healing hydrogel material by mass.

[0028] The dynamic crosslinking agent can dynamically crosslink with hydrogen bonds, giving the self-healing hydrogel material excellent self-healing capabilities. Furthermore, the thermally conductive filler, added to the polymer matrix, forms a uniformly distributed three-dimensional network, reducing interfacial thermal resistance, improving the overall stability of the material, and simultaneously enhancing its thermodynamic and mechanical properties. Deionized water can be used as the solvent.

[0029] In self-healing hydrogel materials, polyvinyl alcohol mainly utilizes chain entanglement and hydrogen bonds to construct a stable three-dimensional network structure, thereby improving self-healing performance and structural stability; polyvinylamide mainly affects repairability through viscosity and chain entanglement, forming a more stable physical network in a dynamic cross-linking system; while N-isopropylacrylamide mainly utilizes its thermal responsiveness and dynamic covalent bond structure to affect repairability.

[0030] Furthermore, the molecular weight of polyvinyl alcohol (PVA) is preferably 80,000-120,000. If the molecular weight of PVA is too low, the overall mechanical properties will be weak, which will reduce the self-healing performance of the self-healing hydrogel material; while if the molecular weight of PVA is too high, it will affect the solubility and processability of the self-healing hydrogel material, making it inconvenient for subsequent processing and use. The molecular weight of polyvinyl alcohol (PVA) is preferably greater than or equal to 10 million, which can form a denser physical cross-linked network.

[0031] The plasma-treated graphene nanosheets are obtained by argon plasma irradiation, i.e., by plasma-activating graphene to obtain plasma-treated graphene nanosheets; the preparation method of plasma-activated graphene can be that the graphene nanosheets are placed in a vacuum reaction chamber (10). -2 In an argon atmosphere (Tor), the graphene nanosheets were irradiated with 400W plasma for 15 minutes; and the volume fraction of the treated graphene nanosheets was controlled at 5-8 vol%, so that the treated graphene nanosheets could be directly dispersed in the polymer matrix.

[0032] The polymer matrix may be a mixture of polyvinyl alcohol and N-isopropylacrylamide, wherein the mass ratio of polyvinyl alcohol to N-isopropylacrylamide is preferably 5:(3-6).

[0033] In the dynamic crosslinking agent, the iron-containing crosslinking agent may be at least one of the following: a mixture of soluble iron salt and acrylic polymer, a complex obtained by reacting soluble iron salt and acrylic polymer, a mixture of soluble iron salt and catechol, and a mixture of soluble iron salt and citric acid; the calcium-containing crosslinking agent may be at least one of the following: a mixture of soluble calcium salt and sodium alginate, a mixture of soluble calcium salt and carboxymethyl cellulose, and a mixture of soluble calcium salt and polyacrylic acid. The soluble iron salt may be ferric chloride, ferric sulfate, ferric nitrate, etc., and the soluble calcium salt may be calcium chloride, calcium nitrate, calcium acetate, etc.

[0034] Furthermore, in the iron-containing crosslinking agent, the molar ratio of the two is preferably 1:1 to 6:1. In the calcium-containing crosslinking agent, the molar ratio is preferably 3:1 to 6:1. Taking the complex obtained by the reaction of soluble iron salt and acrylic polymer as an example, when the molar ratio of soluble iron salt to acrylic polymer is greater than 6:1, some iron ions are not fully complexed with the acrylic polymer and exist in a free state, affecting the overall stability and uniformity of the complex, and affecting the stability of the subsequently prepared self-healing hydrogel material; when the molar ratio of soluble iron salt to acrylic polymer is less than 1:1, the coordination sites on the acrylic polymer cannot be fully occupied by iron ions, resulting in incomplete complex formation, and some acrylic polymer exists in a free state, reducing the stability and binding force of the complex, which also affects the stability of the subsequently prepared self-healing hydrogel material.

[0035] The self-healing hydrogel material may further include bismuth telluride, wherein the bismuth telluride accounts for 5-10 vol% of the volume of the self-healing hydrogel material.

[0036] When bismuth telluride is added to self-healing hydrogel materials, the bismuth telluride causes electrons to migrate in a specific direction under the influence of temperature difference, forming an electric current and realizing thermoelectric conversion, thereby enabling the self-healing hydrogel materials to recover waste heat.

[0037] A method for preparing a self-healing hydrogel material, comprising the following steps: completely dissolving the polymer matrix in a solvent to obtain a matrix solution; adding the thermally conductive filler to the matrix solution and ultrasonically treating it to form a uniform dispersion; adding the dynamic crosslinking agent to the uniform dispersion and stirring to obtain a mixture; subjecting the mixture to freeze-thaw cycles to obtain the self-healing hydrogel material.

[0038] The freeze-thaw cycle treatment is a gradient treatment: First, freeze at -20℃ to -10℃ for 2-6 hours; second, thaw at 5℃ to 15℃ for 1-4 hours; third, stabilize at 20℃ to 35℃ for 1-4 hours; fourth, repeat the operations of the first to third steps 2-6 times. Specifically, the freeze-thaw cycle treatment can be as follows: first freeze at -15℃ for 4 hours, then thaw at 10℃ for 2 hours, and finally stabilize at 28℃ for 2 hours, with the number of cycles being 2-6 times.

[0039] By employing a freeze-thaw cycle treatment method, the polymer matrix can be tightly packed during the preparation of self-healing hydrogel materials. The polymer matrix and thermally conductive filler are dynamically cross-linked multiple times through dynamic cross-linking agents and solvents, forming more thermally conductive channels, thereby improving the structural stability and thermal conductivity of the self-healing hydrogel materials. Furthermore, more dynamic reversible cross-linking points are formed within the structure of the self-healing hydrogel materials, enhancing their self-healing properties.

[0040] Furthermore, during freeze-thaw cycles, excessively low freezing temperatures and prolonged freezing times can lead to excessive compression of polymer chains by ice crystals, resulting in localized stress concentration and microcracks after thawing, thus damaging the internal structural integrity of the self-healing hydrogel material. Conversely, excessively high freezing temperatures and short freezing times can cause the self-healing hydrogel material to become structurally loose, reducing its mechanical strength and self-healing efficiency. Conversely, excessively high thawing temperatures and premature thawing can damage the internal structural integrity of the self-healing hydrogel material and hinder chain segment recombination, affecting its self-healing performance. Conversely, excessively low thawing temperatures and prolonged thawing times can cause partial melting of crystals, reducing physical cross-linking points and lowering the strength of the self-healing hydrogel material. In addition, excessive cycles can lead to over-cross-linking and loss of chain segment mobility, thereby causing the self-healing function to fail.

[0041] A method for preparing a self-healing hydrogel material reveals that the self-healing hydrogel material can adaptively fill or repair microcracks at the interface, maintain the heat conduction path, and has strong self-healing ability and a long service life.

[0042] Example 1: A method for preparing a self-healing hydrogel material, the specific steps of which are as follows.

[0043] Step 1: Dissolve polyvinyl alcohol (PVA) with a molecular weight of 92,000 and N-isopropylacrylamide (PNIPAM) in deionized water at a mass ratio of 5:4 (total concentration 12wt%), and mechanically stir at 100°C for 6 hours until completely dissolved to form a temperature-responsive matrix (volume shrinkage rate of 42±2% at 32°C).

[0044] Step 2: Add 8 vol% plasma-treated graphene nanosheets to the temperature-responsive matrix from Step 1, and sonicate at 350 W for 45 minutes to obtain a uniform dispersion. Plasma treatment parameters: 400 W irradiation in an argon atmosphere for 15 minutes (vacuum degree 10). -2 Torr) improves dispersion by 300%.

[0045] Step 3: Add ferric ammonium citrate-polyacrylic acid complex (molar ratio 1:2, accounting for 3 mol% of the polymer matrix) to the homogeneous dispersion obtained in Step 2, and stir at 60°C for 40 minutes to form a Fe... 3+ A mixture of -carboxyl dynamic networks (coordination bond binding energy 42 kJ / mol).

[0046] Step 4: The mixture obtained in Step 3 was subjected to a gradient freeze-thaw cycle to facilitate molding. First, it was deep-frozen at -15℃ for 4 hours to form PVA microcrystal nuclei (size 50±5nm). Then, it was thawed at 10℃ for 2 hours to promote iron ion migration and recombination. Next, it was stabilized at 28℃ for 2 hours to complete the directional alignment of PNIPAM segments. The entire process was repeated 4 times to obtain the first self-healing hydrogel material sample. The total processing time was 32 hours.

[0047] The self-healing hydrogel material sample 1 has a thermal conductivity of 1.0 W / mK, a tensile stress of 72.9 kPa, and an elongation at break of 685.8%.

[0048] Example 2 discloses a method for preparing a self-healing hydrogel material. The only difference between Example 1 and Example 2 is that in step 1, polyvinyl alcohol (PVA) and N-isopropylacrylamide (PNIPAM) are replaced with polyvinyl alcohol, ultimately yielding self-healing hydrogel material sample 2. Self-healing hydrogel material sample 2 exhibits temperature responsiveness, with a 42% increase in shrinkage at 32°C, while its mechanical strength decreases by 25% compared to self-healing hydrogel material sample 1.

[0049] Example 3 illustrates a method for preparing a self-healing hydrogel material. The only difference between Example 1 and Example 3 is that in step 2, the plasma-treated graphene nanosheets are replaced with carbon nanotubes, ultimately yielding sample 3 of the self-healing hydrogel material. Sample 3 exhibits a thermal conductivity of 1.8 W / mK.

[0050] Example 4 illustrates a method for preparing a self-healing hydrogel material. The only difference between Example 1 and Example 4 is that in step 2, 8 vol% bismuth telluride is added, ultimately yielding self-healing hydrogel material sample 4. The waste heat recovery rate of self-healing hydrogel material sample 4 is 4%.

[0051] Reference Figure 1 and Figure 2A thermal management module for a hydrogen storage tank includes several processing units 4 and metal partitions 6. Adjacent processing units 4 are separated by the metal partitions 6. Each processing unit 4 includes a hydrogen storage layer 41, a phase change layer 42, and a metal perforated plate 5. The metal perforated plate 5 is located between the hydrogen storage layer 41 and the phase change layer 42.

[0052] Reference Figure 3 and Figure 4 The metal perforated plate 5 has a plurality of holes 51, and the holes 51 are filled with a self-healing coating 511. The material of the self-healing coating 511 is the self-healing hydrogel material as described above. In addition, the hydrogen storage tank thermal management module also includes an outer wall 1 of the hydrogen storage tank, a plurality of processing units 4 and a metal partition 6 are all disposed in the inner cavity of the outer wall 1, and the outer wall 1 is also provided with inlet and outlet 3, which are used to absorb and release hydrogen gas.

[0053] In some embodiments, an insulation layer 2 is also provided on the inner side of the outer wall 1 to prevent internal heat from being transferred out, which would cause the internal reaction temperature to be unstable and affect the service life of the hydrogen storage tank thermal management module; at the same time, it would make the hydrogen storage tank thermal management module inconvenient to access, move or transport.

[0054] A metal perforated plate is placed between the hydrogen storage layer and the phase change layer, and a self-healing coating (i.e., a self-healing hydrogel material) is used to help adapt to the volume changes of the hydrogen storage layer, while avoiding direct contact between the phase change layer and the hydrogen storage layer to prevent unnecessary chemical reactions. Simultaneously, metal partitions are also placed between the processing units to provide hydrogen transport channels between the stacked units, ensuring sufficient contact between hydrogen and the hydrogen storage layer, facilitating hydrogen absorption and release.

[0055] The thickness of the hydrogen storage layer is preferably 5-20 mm, the thickness of the phase change layer is 4-12 mm, and the thickness of the metal perforated plate is 0.5-1.5 mm.

[0056] The hydrogen storage layer can be made of MgH2 briquettes. When the thickness of the hydrogen storage layer is too low, the hydrogen storage capacity of the thermal management module of the hydrogen storage tank will be insufficient. When the thickness of the hydrogen storage layer is too high, the diffusion path will be too long, which will reduce the hydrogen absorption and desorption capacity of the thermal management module of the hydrogen storage tank.

[0057] The phase change layer material can be a NaNO3-KNO3 eutectic salt, or a NaNO3-KNO3 eutectic salt encapsulated in silicon oxide, wherein the particle size of silicon oxide can be 50-100μm. When the thickness of the phase change layer is too low, the thermal buffer time of the hydrogen storage tank thermal management module will be insufficient; when the thickness of the phase change layer is too high, the volumetric energy density of the hydrogen storage tank thermal management module will decrease.

[0058] The pore diameter is preferably 1.5-2 mm, the spacing between adjacent pores is 0.5-6 mm, and the pores are filled with at least 90% of the self-healing hydrogel material.

[0059] The self-healing hydrogel material used for filling the holes provides excellent self-healing properties, ensuring the structural stability of the hydrogen storage tank's thermal management module and extending its service life. However, if the pore size is too small, it becomes difficult to fill; if the pore size is too large, it reduces the structural strength of the module. Conversely, if the pore spacing is too large, the self-healing hydrogel material filling the metal orifice plate will be too far apart, failing to provide sufficient hydrogen transport channels to ensure adequate contact between the hydrogen and the storage layer, making the metal orifice plate prone to cracking during hydrogen storage. Conversely, if the pore spacing is too small, stress concentration will occur, reducing the structural stability of the thermal management module.

[0060] The metal separator and metal perforated plate can be made of flexible metal or flexible metal alloy, preferably nickel-titanium alloy, to separate the phase change layer from the hydrogen storage layer. When the thickness of the metal separator or metal perforated plate is too low, the mechanical strength of the hydrogen storage tank thermal management module is insufficient; when the thickness of the metal separator is too high, it increases manufacturing costs; when the thickness of the metal perforated plate is too high, the shape memory effect weakens, and the self-healing hydrogel material cannot provide a good self-healing effect. More preferably, the pores are filled with 100% self-healing hydrogel material, which facilitates a tight bond between the self-healing hydrogel material and the metal perforated plate interface. This allows it to adapt to volume changes in the hydrogen storage layer, maintain stable thermal interface contact, and maintain the heat conduction path. This ensures that the thermal management module of the hydrogen storage tank maintains its thermal management efficiency without decline or only slightly declines after long-term cycling, extending the service life of the hydrogen storage tank thermal management module.

[0061] Furthermore, a self-healing hydrogel material can be sprayed onto the surface of the hydrogen storage layer. This allows the self-healing hydrogel material to adapt to changes in the volume of the hydrogen storage layer, maintaining stable thermal interface contact and preserving the heat conduction path. The spraying thickness can be 10-100 μm, which is sufficient to maintain stable thermal interface contact while reducing the amount of self-healing hydrogel material required, thus lowering the preparation cost.

[0062] The specific hydrogen absorption process of the hydrogen storage tank's thermal management module is as follows: Hydrogen enters the hydrogen storage tank through the inlet and outlet, diffuses to the hydrogen storage layer through the central channel and the metal perforated plates between different processing units, and expands in volume after absorbing hydrogen, generating compressive stress on adjacent structures. The self-healing hydrogel material covering the surface of the hydrogen storage layer undergoes elastic deformation due to its high flexibility, adhering to the expanded surface of the hydrogen storage layer. The micro-gaps generated during the expansion process are immediately filled by the self-healing hydrogel material, maintaining the heat conduction path. The metal perforated plates expand and deform accordingly, squeezing the self-healing hydrogel material within their pores to the surrounding area, avoiding localized stress concentration. The heat released during hydrogen absorption is efficiently conducted to the adjacent phase change layer through the self-healing hydrogel material. The phase change layer absorbs heat and melts, suppressing the temperature rise inside the tank and maintaining a stable reaction temperature.

[0063] The specific hydrogen release process is as follows: During hydrogen release, the volume of the hydrogen storage layer shrinks to its original state, creating micron-sized air gaps at the interface. The self-healing hydrogel material, relying on its elastic recovery force (with shape memory assistance provided by the metal perforated plate), re-adheres onto the surface of the shrunken hydrogen storage layer. Through the dynamic recombination of the self-healing hydrogel material, it automatically repairs the local cracks caused by shrinkage stress and fills the newly formed air gaps, controlling the increase in interfacial thermal resistance. Hydrogen release is an endothermic reaction; the solidification of the phase change layer releases heat, which is transferred to the hydrogen storage layer through the self-healing hydrogel material to maintain the reaction temperature.

[0064] Example 1, a sample 1 of a hydrogen storage tank thermal management module, includes several processing units and a metal partition. Adjacent processing units are separated by the metal partition. Each processing unit includes a hydrogen storage layer, a phase change layer, and a metal perforated plate. The metal perforated plate is located between the hydrogen storage layer and the phase change layer. The metal perforated plate has several holes, and the holes are filled with a self-healing coating. The material of the self-healing coating is a self-healing hydrogel material sample 1.

[0065] The hydrogen storage layer is made of MgH2 compressed material with a thickness of 10 mm; the phase change layer is made of NaNO3-KNO3 eutectic salt with a thickness of 8 mm; the metal perforated plate and the metal separator are both made of nickel-titanium alloy with a thickness of 1.0 mm. The pores on the metal perforated plate have a diameter of 1.0 mm and a pore spacing of 2 mm. The pores are filled with 100% self-healing hydrogel material sample one.

[0066] Example 2, Hydrogen Storage Tank Thermal Management Module Sample 2, differs from Hydrogen Storage Tank Thermal Management Module Sample 1 only in that the self-healing coating material is self-healing hydrogel material Sample 2.

[0067] Example 3, hydrogen storage tank thermal management module sample 3, differs from hydrogen storage tank thermal management module sample 1 only in that the self-healing coating material is self-healing hydrogel material sample 3.

[0068] Example 4, hydrogen storage tank thermal management module sample 4, differs from hydrogen storage tank thermal management module sample 1 only in that the self-healing coating material is self-healing hydrogel material sample 4.

[0069] Comparative Example 1, compared to Sample 1, differs from Sample 1 of the hydrogen storage tank thermal management module only in that the self-healing coating material is silicone grease.

[0070] The hydrogen storage tank thermal management module samples 1 to 4 of Examples 1 to 4 and the comparative sample 1 of Comparative Example 1 were filled with hydrogen and thermal resistance tests were performed. The performance test results of the hydrogen storage tank thermal management module samples 1 to 4 and the comparative sample 1 are shown in Table 1 below.

[0071] Table 1. Performance test results of hydrogen storage tank thermal management module samples 1-4 and comparative sample 1.

[0072] As shown in the table above, the thermal management module of the hydrogen storage tank in this application can adaptively fill the microcracks at the interface through self-healing hydrogel material, maintain the heat conduction path, and has good self-healing ability and structural stability, and has a long service life.

[0073] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions in the examples of this application.

Claims

1. A self-healing hydrogel material, characterized in that, include: Polymer matrix, thermally conductive filler, dynamic crosslinking agent, and solvent; The polymer matrix is ​​at least one of polyvinyl alcohol, polyacrylamide, and N-isopropylacrylamide, and the polymer matrix accounts for 5-15 wt% of the self-healing hydrogel material. The thermally conductive filler is plasma-treated graphene nanosheets or carbon nanotubes, and the thermally conductive filler accounts for 5-8% of the volume fraction of the self-healing hydrogel material. The dynamic crosslinking agent is at least one of iron-containing crosslinking agents and calcium-containing crosslinking agents, and the molar fraction of the dynamic crosslinking agent in the polymer matrix is ​​1-5 mol%. The solvent accounts for 0.1-50 wt% of the self-healing hydrogel material.

2. The self-healing hydrogel material according to claim 1, characterized in that: The plasma-treated graphene nanosheets were obtained by argon plasma irradiation.

3. The self-healing hydrogel material according to claim 1, characterized in that: The iron-containing crosslinking agent is at least one of the following: a mixture of soluble iron salt and acrylic polymer, a complex obtained by reacting soluble iron salt and acrylic polymer, a mixture of soluble iron salt and catechol, and a mixture of soluble iron salt and citric acid; the calcium-containing crosslinking agent is at least one of the following: a mixture of soluble calcium salt and sodium alginate, a mixture of soluble calcium salt and carboxymethyl cellulose, and a mixture of soluble calcium salt and polyacrylic acid.

4. The self-healing hydrogel material according to claim 1, characterized in that, The self-healing hydrogel material also includes bismuth telluride, which accounts for 5-10 vol% of the volume of the self-healing hydrogel material.

5. A method for preparing a self-healing hydrogel material according to any one of claims 1 to 4, characterized in that, Includes the following steps: The polymer matrix is ​​completely dissolved in a solvent to obtain a matrix solution; The thermally conductive filler is added to the matrix solution, and a uniform dispersion is formed after ultrasonic treatment. The dynamic crosslinking agent was added to the uniform dispersion, and the mixture was stirred to obtain a mixture. The mixture was subjected to freeze-thaw cycles to obtain a self-healing hydrogel material.

6. The method for preparing the self-healing hydrogel material according to claim 5, characterized in that, The freeze-thaw cycle is a gradient process: First, freeze at -20℃ to -10℃ for 2-6 hours; second, thaw at 5℃ to 15℃ for 1-4 hours; third, stabilize at 20℃ to 35℃ for 1-4 hours; fourth, repeat the operations from the first to the third step 2-6 times.

7. A thermal management module for a hydrogen storage tank, characterized in that, The device comprises several processing units and a metal partition, with adjacent processing units separated by the metal partition. Each processing unit includes a hydrogen storage layer, a phase change layer, and a metal orifice plate. The metal orifice plate is located between the hydrogen storage layer and the phase change layer. The metal orifice plate has several holes, and the holes are filled with a self-healing coating. The material of the self-healing coating is a self-healing hydrogel material according to any one of claims 1 to 4.

8. The hydrogen storage tank thermal management module according to claim 7, characterized in that, The thickness of the hydrogen storage layer is 5-20 mm, the thickness of the phase change layer is 4-12 mm, and the thickness of the metal perforated plate is 0.5-1.5 mm.

9. The hydrogen storage tank thermal management module according to claim 7, characterized in that, The pores have a diameter of 1.5-2 mm, the spacing between adjacent pores is 0.5-6 mm, and the pores are filled with at least 90% of the self-healing hydrogel material.

10. The hydrogen storage tank thermal management module according to claim 7, characterized in that, The surface of the hydrogen storage layer is coated with the self-healing hydrogel material.

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