Thermotropic flexible composite phase change materials coupled with multi-crosslinked network aerogel materials and their thermal protection applications

Abstract

This invention relates to a thermotropic flexible composite phase change material coupled with a multi-layer cross-linked network aerogel material and its application in thermal protection, belonging to the field of new materials technology. The coupled material consists of a multi-layer cross-linked network aerogel, a thermotropic flexible composite phase change material, and a binder. The thermotropic flexible composite material is a hydrated inorganic salt phase change material, the binder is a flame-retardant inorganic binder, and the multi-layer cross-linked network aerogel is a sodium alginate / gelatin composite material, which is cross-linked through a dual cross-linking agent to form a stable multi-layer network structure to increase the flame retardant properties and mechanical strength of the aerogel. The prepared coupled material exhibits high flame retardant properties and good thermal insulation properties, making it highly suitable for large-scale applications in thermal protection in buildings, batteries, and electronic devices.

Description

Technical Field

[0001] This invention relates to thermo-induced flexible composite phase change materials coupled with multi-crosslinked network aerogel coupling materials and their thermal protection applications, which belong to the field of new materials technology. Background Technology

[0002] In recent years, the application of thermal runaway protection materials in buildings, batteries, and electronic devices has received increasing attention due to their crucial role in improving safety and functional reliability. For example, in the construction sector, the fire risks faced by modern high-rise buildings and enclosed spaces make thermal runaway protection materials an important part of the design. These materials not only significantly improve the fire resistance of buildings but also effectively insulate against high temperatures, slow the spread of fire, and protect the building structure from damage caused by extreme heat. In electronics, with the increase in device power density, thermal runaway has become a major challenge. Electronic devices may generate excessive heat when operating under high loads, leading to system overheating and potential malfunctions. Thermal runaway protection materials can play a vital role in the design of these devices, providing time for response through effective thermal management. Similarly, in battery technology, especially in the application of lithium-ion batteries, thermal runaway has become a serious safety hazard. In recent years, fires and explosions caused by lithium battery thermal runaway have occurred frequently. This is because when a single lithium battery cell is overcharged, short-circuited, or subjected to other abuse, it generates a large amount of heat in a short period of time. When the battery temperature reaches 100–130 °C, the separator begins to melt, causing an internal short circuit and potentially leading to thermal runaway, posing a high risk of fire or even explosion. More seriously, to meet high energy demands, multiple individual cells are typically assembled into a battery module. If a single cell in the module experiences thermal runaway, the heat can spread to adjacent cells via heat transfer, causing the entire battery module to run away with the heat. Compared to individual cells, the heat and hazards released by the thermal runaway of the entire battery module are far more severe, potentially leading to catastrophic fires or explosions. Therefore, developing suitable thermal protection materials to improve the thermal safety of the entire battery module is crucial. Currently, thermal protection materials used for lithium-ion battery thermal runaway are mainly divided into two categories: insulating materials, such as aerogels, and endothermic materials, such as phase change materials. These materials delay the accumulation and transfer of heat through insulation or absorption, buying more time for cooling and safe handling of the lithium-ion battery.

[0003] In recent years, aerogel materials, as a representative of thermal insulation materials, have been considered most suitable for thermal insulation applications due to their low thermal conductivity, ultra-light weight, and low bulk density. For example, inorganic aerogels (such as SiO2) have extremely low thermal conductivity, but are difficult to mold, limiting their widespread application; while organic aerogels (such as polyurethane and polyimide) are easier to mold, but their synthesis process is complex, involving toxic solvents and raw materials, which may cause environmental pollution. In contrast, aerogels based on natural biomass have attracted widespread attention from researchers due to their wide availability, low cost, and environmental friendliness. However, biomass aerogels also have drawbacks. For example, sodium alginate aerogels have poor mechanical properties; and gelatin aerogels derived from collagen are flammable and have poor smoke suppression. Therefore, developing high-performance biomass-based composite aerogels with both good mechanical properties and flame retardant properties is of great significance for their application in the thermal protection of lithium batteries, but this challenge remains significant.

[0004] As a representative of heat-absorbing materials, phase change materials (PCMs) are considered suitable for thermal protection due to their high latent heat density and small volume change, allowing them to absorb a large amount of heat during phase change. However, most PCMs currently used for lithium-ion battery thermal management are organic solid-liquid PCMs. Although chemically stable, their flammability is a fatal flaw. In the event of thermal runaway in a lithium-ion battery, flammable organic PCMs may increase the thermal hazards of the entire battery system, raising the risk of combustion and explosion. In contrast, inorganic solid-liquid PCMs are not only completely non-flammable and cheaper, but also have a higher latent heat value. However, inorganic PCMs suffer from leakage and rigid crystallization problems. Overcoming these problems and endowing them with flexibility is of great significance for their application in thermal protection.

[0005] Besides the inherent problems of the materials themselves, the two main categories of thermal protection materials mentioned above also face challenges in their application to thermal protection. For example, as the energy density of lithium batteries increases, aerogels become unable to block all excess heat once thermal saturation occurs. The same applies to phase change endothermic materials; once their latent heat and thermochemical heat storage value are exhausted, they can no longer maintain a constant temperature, thus failing to prevent the transfer and spread of excess heat. Therefore, delaying the occurrence of thermal saturation and minimizing heat diffusion to provide more time for safe battery handling is of great significance for their application in thermal protection. Summary of the Invention

[0006] To address the aforementioned issues, this paper presents a biomass-based composite aerogel with a multi-layered crosslinking network, using gelatin combined with sodium alginate as the aerogel matrix and glutaraldehyde and boric acid as dual crosslinking agents. Simultaneously, a thermotropic flexible composite phase change material was successfully prepared by using inorganic solid-liquid phase change materials (such as SAT) as the phase change matrix and thermoplastic polyester elastomers (such as TPEE) and thermally conductive reinforcing agents (such as EG) as encapsulation materials. Furthermore, this invention proposes for the first time to couple the Ge / SA composite aerogel with the thermotropic flexible composite phase change material (such as SAT / TPPE / EG) using an adhesive. This allows the SAT / TPPE / EG composite phase change material to continuously "charge and store energy" for the Ge / SA aerogel, promptly absorbing and removing heat, thereby delaying thermal saturation and maximizing the thermal insulation duration of the composite material. This also slows heat diffusion, making it well-suited for application in the field of lithium battery thermal protection.

[0007] This coupling material is a multi-crosslinked network aerogel coupled with a thermotropic flexible composite phase change material. By mass percentage, it consists of 0.5–1.5 wt% multi-crosslinked network aerogel, 96.5–97.5 wt% thermotropic flexible composite phase change material, and 1–3 wt% binder. The thermotropic flexible composite material is a hydrated inorganic salt phase change material, the binder is a flame-retardant inorganic binder, and the multi-crosslinked network aerogel is a sodium alginate / gelatin composite material. It is crosslinked through a dual crosslinking agent to form a stable multi-network structure, which enhances the flame-retardant properties and mechanical strength of the aerogel.

[0008] Preferably, the thermotropic flexible composite phase change material is composed of 72-82 wt% inorganic solid-liquid phase change material, 1.0-2.0 wt% thermal conductivity enhancer, and 17-27 wt% polymer support material by mass percentage. The phase change material can maintain a uniform and stable shape, meeting thermal protection requirements.

[0009] Preferably, the inorganic solid-liquid phase change material is one to three of the following: sodium acetate trihydrate, calcium sulfate dihydrate, potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, magnesium chloride hexahydrate, magnesium sulfate heptahydrate, calcium nitrate tetrahydrate, zinc chloride hexahydrate, and sodium thiosulfate pentahydrate.

[0010] Preferably, the thermal conductivity enhancer is one to three of the following: expanded graphite, carbon nanotubes, carboxylated carbon nanotubes, graphene, graphene oxide, titanium dioxide, aluminum oxide, zinc oxide, sodium chloride, nano-silver, nano-copper, and nano-gold.

[0011] Preferably, the polymer support material is one to three of the following polymer support materials: styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butene-styrene block copolymer (SEBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and thermoplastic polyester elastomer (TPEE).

[0012] More preferably, the multi-crosslinked network aerogel comprises, by weight percentage, 50%~70wt% gelatin, 29~49wt% sodium alginate, 0.5~3wt% boric acid (crosslinking agent), and 0.5~3wt% glutaraldehyde (crosslinking agent). The multi-crosslinked network aerogel exhibits high thermal insulation and flame retardant properties, meeting thermal protection requirements.

[0013] Another object of the present invention is to provide a method for preparing the above-mentioned multi-crosslinked network aerogel coupled thermally induced flexible composite phase change material.

[0014] The method includes the following steps:

[0015] (1) Mix gelatin and sodium alginate and stir and heat to dissolve in acetic acid solution; then add boric acid, stir and then add glutaraldehyde solution;

[0016] After stirring together, the resulting solution is placed into a mold, then frozen, and finally freeze-dried in a freeze dryer to obtain Ge / SA aerogel;

[0017] (2) Dissolve the polymer support material in dichloromethane solution until it is uniformly dissolved.

[0018] Secondly, the inorganic solid-liquid phase change material is heated to a liquid state, and a thermal conductivity enhancer is added to it for adsorption. Then, it is crushed using a ball mill and added to a polymer support material solution for mixing and adsorption. The solvent is removed to obtain a thermotropic flexible composite phase change material.

[0019] (3) The adhesive is coated on the surface of the thermo-flexible composite phase change material, and then Ge / SA aerogel is placed on its surface and cured at room temperature to obtain a multi-crosslinked network aerogel coupled thermo-flexible composite phase change material.

[0020] Preferably, the specific steps are as follows:

[0021] (1) Mix 1.0 g gelatin (Ge) and 0.4 g sodium alginate (SA) and stir and heat to dissolve in acetic acid solution. Then, add 0.01 g boric acid and stir for 2 h, then add 167 μL glutaraldehyde solution. After stirring together for 0.5 h, put the resulting solution into a mold and freeze it in a -20℃ refrigerator for 12 h. Finally, freeze-dry it in a freeze dryer for 24 h to obtain Ge / SA aerogel;

[0022] (2) At 50°C, thermoplastic polyester elastomer (TPEE) was dissolved in a solvent. After half an hour, the TPEE was uniformly dissolved. Next, SAT was heated to a liquid state at 50°C, and expanded graphite (EG) was added for adsorption. The adsorbed powder was then crushed using a ball mill and mixed with the TPEE solution. The mixture was then placed in a vacuum drying oven at 50°C for two hours for adsorption. Subsequently, the mixture was placed in the air to promote the evaporation of the dichloromethane solvent. Finally, the sample was placed in a vacuum drying oven for 24 hours to remove the residual dichloromethane solvent, thus obtaining a thermotropic flexible composite phase change material.

[0023] (3) Apply the adhesive to the surface of the thermo-flexible composite phase change material, then place the Ge / SA aerogel on its surface, and then cure at room temperature for 48 h.

[0024] In the above technical solution, the solvent is preferably one to three of the following: tetrahydrofuran, dioxane, petroleum ether, acetone, butanone, chloroform, dichloromethane, carbon tetrachloride, carbon disulfide, DMF, DMSO, benzene, toluene, xylene, nitrobenzene, chlorobenzene, cyclohexane, or n-hexane.

[0025] Another object of the present invention is the application of the aforementioned multi-crosslinked network aerogel-coupled thermo-flexible composite phase change material, which is used in the field of thermal protection in buildings, batteries and electronic devices.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention leverages the chemical cross-linking network formed by gelatin and glutaraldehyde to provide mechanical strength to the composite aerogel; it also utilizes the hydrogen-bonded cross-linking network formed by sodium alginate and boric acid to enhance the flame-retardant properties of the composite aerogel; thus constructing a biomass composite aerogel with both good mechanical properties and flame retardancy. Simultaneously, by utilizing the elastic support properties of polymer support materials (such as TPEE) and the porous adsorption characteristics of the thermal conductivity enhancer EG, a thermotropic flexible composite phase change material is constructed through a dual encapsulation strategy. Finally, an adhesive couples the two components together, maximizing the thermal protection performance of the coupled material.

[0028] Sodium acetate trihydrate has two main thermal storage stages: latent heat storage (58 °C) and thermochemical thermal storage (106-140 °C). These two temperature stages can not only provide early warning of thermal runaway, but also inhibit heat propagation when thermal runaway occurs.

[0029] In this invention, the thermotropic flexible composite phase change material can continuously "charge and store energy" for Ge / SA aerogel like a power bank, and absorb and remove heat from the thermotropic flexible composite phase change material in a timely manner, thereby delaying the occurrence of thermal saturation and maximizing the thermal insulation duration of the composite material. It also slows down heat diffusion, making it well-suited for thermal protection applications in construction, electronic devices, lithium batteries, and other fields. Compared with uncoupled thermotropic flexible composite phase change materials / aerogel materials, its thermal protection effect is greatly improved.

[0030] To evaluate the thermal protection effect of the prepared coupling material, we chose to conduct a practical simulated thermal insulation test. A ceramic heating plate (35*21*5 mm) was used to simulate a high-temperature environment to evaluate the thermal insulation performance of the composite material. First, the material to be evaluated was placed on the ceramic heating plate and fixed with a mold. Then, thermocouples were placed on both sides of the sample. Subsequently, a DC regulated power supply (IT6722A, ITECH Electronics Co., Ltd., China) was used to heat the ceramic heating plate, and a temperature recorder (MIK-R5000C, Hangzhou Meikong Automation Technology Co., Ltd., China) was used to record the temperature difference between the two sides of the sample to evaluate the thermal insulation performance of the sample.

[0031] This invention tested the thermal insulation performance of the Ge / SA-STE composite material formed by Ge / SA composite aerogel on top and SAT / TPPE / EG on top. It can be seen that the bonding method with Ge / SA composite aerogel on top, closer to the heat source, exhibits superior thermal insulation performance, controlling the temperature below 90 °C. Furthermore, this invention also measured the thermal insulation performance of STE and Ge / SA aerogel at the same thickness. It was found that the final top temperature of STE was approximately 182 °C, while the final top temperature of GE / SA was 111 °C, both lower than the thermal insulation performance of the coupling at the same thickness. This demonstrates the superiority of the coupling material of this invention, possessing excellent thermal protection capabilities and significant practical application value.

[0032] The results show that the prepared Ge / SA-STE coupling material exhibits excellent thermal insulation performance; even at a high temperature of 200 °C for 60 minutes, the temperature at its top remains at 88 °C. Furthermore, this coupling material also possesses excellent flame-retardant properties, making it highly suitable for large-scale application in the field of lithium battery thermal protection, delaying the occurrence of thermal runaway in lithium batteries. Attached Figure Description

[0033] Figure 1 In Example 1, a is the infrared spectrum of Ge aerogel, SA aerogel and Ge / SA aerogel; b is the pore size distribution corresponding to the nitrogen adsorption-desorption curve of Ge, SA and Ge / SA composite aerogel in Example 1; c is the pore size distribution corresponding to the cumulative mercury intrusion porosimetry of Ge, SA and Ge / SA composite aerogel in Example 1.

[0034] Figure 2 In Example 1, a represents the compressive strength of Ge aerogel, SA aerogel, and Ge / SA aerogel; b represents the limiting oxygen index of Ge, SA, and Ge / SA composite aerogels in Example 1; and c represents the thermal insulation effect of Ge, SA, and Ge / SA composite aerogels in Example 1.

[0035] Figure 3 Image a shows the morphology of SAT changing with heating time in Implementation Case 1; image a shows the morphology of STE changing with heating time.

[0036] Figure 4 In Figure 'a', STE is shown as a bending photograph at different temperatures in Implementation Case 1.

[0037] Figure 5 In Figure a, the DSC spectra of SAT, SAT / TPEE, and SAT / TPEE / EG in Implementation Case 1 are shown; b shows the limiting oxygen index of SAT / TPEE and SAT / TPEE / EG; c shows the thermal insulation performance of the heating plate and SAT / TPEE / EG at different thicknesses.

[0038] Figure 6 In Example 1, a represents the thermal insulation performance of the heating plate and Ge / SA-STE with different bonding methods; b represents the thermal insulation performance of the heating plate, Ge / SA, and STE in Example 1. Detailed Implementation

[0039] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0040] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0041] One of the specific implementation methods:

[0042] A method for preparing and applying a multi-crosslinked network aerogel coupled thermo-induced flexible composite phase change material, wherein the coupled material comprises, by mass percentage, the following components:

[0043] Multi-crosslinked network aerogel: 0.5~1.5wt%

[0044] Thermotropic flexible composite phase change material: 96.5~97.5 wt%;

[0045] Adhesive: 1~3wt% composition.

[0046] The thermo-flexible composite material is composed of the following components by mass percentage:

[0047] Inorganic solid-liquid phase change materials: 72~82wt%

[0048] Thermal conductivity enhancer: 1.0~2.0wt%;

[0049] Polymer support material: 17~27wt%.

[0050] The multi-crosslinked network aerogel is composed of the following components by mass percentage:

[0051] Gelatin: 50%~70wt%;

[0052] Sodium alginate: 29~49 wt%;

[0053] Crosslinking agent boric acid: 0.5~3wt%;

[0054] Crosslinking agent glutaraldehyde: 0.5~3wt%.

[0055] Preferably, the inorganic solid-liquid phase change material is one to three of the following: sodium acetate trihydrate, barium hydroxide octahydrate, calcium sulfate dihydrate, potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, magnesium chloride hexahydrate, magnesium sulfate heptahydrate, calcium nitrate tetrahydrate, zinc chloride hexahydrate, and sodium thiosulfate pentahydrate.

[0056] Preferably, the thermal conductivity enhancer is one to three of the following: expanded graphite, carbon nanotubes, carboxylated carbon nanotubes, graphene, graphene oxide, titanium dioxide, aluminum oxide, zinc oxide, sodium chloride, nano-silver, nano-copper, and nano-gold.

[0057] Preferably, the polymer support material is one to three of the following: SIS, SBS, SEBS, SEPS, and TPEE.

[0058] Example 1

[0059] (1) Mix 1.0 g gelatin (Ge) and 0.4 g sodium alginate (SA) and stir and heat to dissolve in acetic acid solution. Then, add 0.01 g boric acid and stir for 2 h, then add 200 μL glutaraldehyde solution. After stirring together for 0.5 h, put the resulting solution into a mold and freeze it in a -20℃ refrigerator for 12 h. Finally, freeze-dry it in a freeze dryer for 24 h to obtain Ge / SA aerogel;

[0060] (2) At 50°C, 4.6g of TPEE was dissolved in dichloromethane solution. After half an hour, the TPEE was uniformly dissolved. Next, 19.3g of SAT was heated to liquid state at 50°C, and 2.8g of EG was added for adsorption. The adsorbed powder was then crushed using a ball mill and mixed with the TPEE solution. The mixture was then placed in a vacuum drying oven at 50°C for two hours for adsorption. Subsequently, the mixture was placed in the air to promote the evaporation of the dichloromethane solvent. Finally, the sample was placed in a vacuum drying oven for 24 hours to remove the residual dichloromethane solvent, thus obtaining the STE material.

[0061] (3) Apply adhesive to the surface of STE material, then place aerogel on its surface, and then cure at room temperature for 48 h.

[0062] To evaluate the thermal protection effect of the prepared coupling material, a simulated thermal insulation test was conducted. A ceramic heating plate (35*21*5 mm) was used to simulate a high-temperature environment to evaluate the thermal insulation performance of the composite material. First, the material to be evaluated was placed on the ceramic heating plate and fixed with a mold. Then, thermocouples were placed on both sides of the sample. Subsequently, a DC regulated power supply (IT6722A, ITECH Electronics Co., Ltd., China) was used to heat the ceramic heating plate, and a temperature recorder (MIK-R5000C, Hangzhou Meikong Automation Technology Co., Ltd., China) was used to record the temperature difference between the two sides of the sample to evaluate the thermal insulation performance of the sample.

[0063] Example 2

[0064] The STE material consisted of: inorganic solid-liquid phase change material SAT: 72 wt%; polymer support material TPEE: 27 wt%; and thermal conductivity enhancer EG: 1%. Other conditions were the same as in Example 1.

[0065] Example 3

[0066] The STE material consisted of: inorganic solid-liquid phase change material SAT: 74 wt%; polymer support material TPEE: 25 wt%; and thermal conductivity enhancer EG: 1%. Other conditions were the same as in Example 1.

[0067] Example 4

[0068] The STE material consisted of: inorganic solid-liquid phase change material SAT: 76 wt%; polymer support material TPEE: 23 wt%; and thermal conductivity enhancer EG: 1%. Other conditions were the same as in Example 1.

[0069] Example 5

[0070] The STE material consisted of: inorganic solid-liquid phase change material SAT: 78 wt%; polymer support material TPEE: 21 wt%; and thermal conductivity enhancer EG: 1%. Other conditions were the same as in Example 1.

[0071] Example 6

[0072] The STE material consisted of: inorganic solid-liquid phase change material SAT: 80 wt%; polymer support material TPEE: 19 wt%; and thermal conductivity enhancer EG: 1%. Other conditions were the same as in Example 1.

[0073] Example 7

[0074] From the infrared spectrum of the material ( Figure 1 As can be seen from a) for unmodified gelatin, 3296 cm -1 The value at 1629 cm⁻¹ belongs to the amide A band, which is due to the vibrational absorption of -NH and -OH groups in gelatin. -1 The amide I band, representing gelatin, is a characteristic band of the stretching vibrations of C=O and the Schiff base (C=N). The amide II band is at 1540 cm⁻¹. -1 Nearby, the region corresponds to the CN stretching and NH bending vibrations of proteins. The amide III band is located at 1235 cm⁻¹. -1 Nearby, the absorption peaks correspond to the CN stretching vibration and NH bending vibration of gelatin. After adding glutaraldehyde for crosslinking and sodium alginate, the changes in functional groups are mainly reflected in the absorption peaks of the amino and aldehyde groups. In the GE / SA spectrum after crosslinking, the absorption peaks of amide I, amide II, and amide III are located at 1628 cm⁻¹. -1 1537 cm -1 and 1238 cm -1 At this location, the positions of the characteristic absorption peaks all shifted, and the intensity of all absorption peaks decreased. This indicates that the aldehyde group in glutaraldehyde underwent a cross-linking reaction with the amino group in gelatin, forming a Schiff base. Furthermore, the absorption peaks of amide A, amide II, and amide III bands all shifted, proving the formation of hydrogen bonds within the gelatin molecule. For SA, 3260 cm⁻¹ -1 The broad characteristic peak at 1594 cm⁻¹ belongs to the -OH group; while at 1594 cm⁻¹... -1 and 1408 cm -1 The absorption characteristic peaks at 1029 cm⁻¹ are attributed to the -COO and CO stretching vibrations of SA, respectively. -1 The absorption peak at that location is attributed to the COC group. The absorption peaks of -OH and -COO show significant changes after the addition of boric acid and gelatin. Figure 1As can be seen in a, in the spectrum of the cross-linked GE / SA, the absorption peak of -OH shifts to 3286 cm⁻¹. -1 At 1627 cm⁻¹, the absorption peaks of -COO and CO shifted to 1627 cm⁻¹, respectively. -1 and 1405 cm -1 This indicates that boric acid and SA are cross-linked through hydrogen bonding.

[0075] Characterization of the material by nitrogen physical adsorption and mercury porosimetry ( Figure 1 As can be seen from bc, the pore size distribution curves of the three aerogels are mainly distributed between 20 and 200 μm, which indicates that the three composite aerogels are mainly composed of macropores.

[0076] From the compressive strength of the material ( Figure 2 As shown in Figure a), the compressive strength of the Ge / SA composite aerogel is higher than that of the Ge and SA composite aerogels. This is attributed to the multiple cross-linked networks formed between them, which significantly enhance the mechanical properties of the Ge / SA composite aerogel material.

[0077] From the infrared spectrum of the material ( Figure 2 As shown in b), Ge aerogel has a limiting oxygen index of only 20.6%, classifying it as a flammable material; while SA aerogel and Ge / SA composite aerogel have limiting oxygen indices of 27.1% and 35.2%, respectively, classifying them as flame-retardant materials. This is mainly attributed to the cross-linking network formed between SA and boric acid, which provides good flame-retardant properties to Ge / SA composite aerogel.

[0078] Figure 2 Figure c shows the thermal insulation effect of Ge / SA composite aerogel. When the thickness is reduced to 5 mm, the temperature difference before and after is 107 ℃, indicating that it has very good thermal insulation performance.

[0079] Figure 3 The images show the shape effects of SAT and STE. It can be seen that after heating for 30 minutes, SAT leaked, while SAT / TPEE / EG maintained its stable shape without leakage.

[0080] Figure 4 The images show the bending of STE at different temperatures. As can be seen from the images, CPCM cannot be bent at 20 ℃, bends slightly at 30 ℃, and can be bent and twisted well in the temperature range of 40-50 ℃. This will help to bond more tightly with the aerogel and improve the thermal protection efficiency.

[0081] Figure 5Figure a shows the DSC spectra of SAT, SAT / TPEE, and SAT / TPEE / EG in Example 1. It can be seen that SAT / TPEE / EG exhibits two peaks, approximately in the ranges of 50-75℃ and 75-150℃, corresponding to latent heat storage and thermochemical heat storage, respectively. These two stages correspond to the loss of one and two water molecules of crystallization in SAT, respectively. The phase transition enthalpy of CPCM was calculated to be 211.5 J / g, the thermochemical decomposition enthalpy to be 600.4 J / g, and the total heat storage density to be 811.9 J / g.

[0082] from Figure 5 In the figure, b represents the limiting oxygen index of SAT / TPEE and SAT / TPEE / EG. It can be seen that both have high limiting oxygen indices, classifying them as flame-retardant materials, indicating that both possess excellent flame retardancy.

[0083] Figure 5 In the figure, 'c' represents the thermal insulation performance of the heating plate and SAT / TPEE / EG at different thicknesses. The results show that the thermal insulation performance gradually increases with increasing thickness. Considering that the thermal protection material should not be too thick, we ultimately chose a thickness of 5 mm as the optimal thickness.

[0084] Figure 6 In Figure a, the thermal insulation performance of the heating plate and the GTE-SAT / TPEE / EG coupling material is shown, while in Figure b, the thermal insulation performance of the Ge / SA composite aerogel and the SAT / TPEE / EG material alone is shown. The results indicate that the Ge / SA composite aerogel, with its bonding method closer to the heat source, exhibits superior thermal insulation performance, controlling the temperature below 90 °C. Furthermore, we measured the thermal insulation performance of STE and Ge / SA aerogels of the same thickness. We found that the final top temperature of STE was approximately 182 °C, while that of GE / SA was only 111 °C, both lower than the thermal insulation performance of the coupling material of the same thickness. This demonstrates the superiority of our coupling material.

[0085] Other methods for preparing this phase change material include: sodium acetate trihydrate, barium hydroxide octahydrate, calcium sulfate dihydrate, potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, magnesium chloride hexahydrate, magnesium sulfate heptahydrate, calcium nitrate tetrahydrate, zinc chloride hexahydrate, and sodium thiosulfate pentahydrate.

[0086] Examples 8-13

[0087] By using barium hydroxide octahydrate instead of sodium acetate trihydrate as the phase change material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with Examples 1-6.

[0088] Examples 14-19

[0089] By using calcium sulfate dihydrate instead of sodium acetate trihydrate as the phase change material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0090] Examples 20-25

[0091] By using potassium aluminum sulfate dodecahydrate instead of sodium acetate trihydrate as the phase change material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0092] Examples 26-31

[0093] By using ammonium aluminum sulfate dodecahydrate instead of sodium acetate trihydrate as the phase change material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0094] Examples 32-37

[0095] Magnesium chloride hexahydrate was used instead of sodium acetate trihydrate as the phase change material to obtain the corresponding thermotropic flexible composite phase change material, with other conditions consistent with those in Examples 1-6.

[0096] Examples 38-43

[0097] Magnesium sulfate heptahydrate was used instead of sodium acetate trihydrate as the phase change material to obtain the corresponding thermotropic flexible composite phase change material, with other conditions consistent with those in Examples 1-6.

[0098] Examples 44-49

[0099] By using calcium nitrate tetrahydrate instead of sodium acetate trihydrate as the phase change material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0100] Examples 50-55

[0101] By using zinc chloride hexahydrate instead of sodium acetate trihydrate as the phase change material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0102] Examples 56-61

[0103] By using sodium thiosulfate pentahydrate alcohol instead of sodium acetate trihydrate as the phase change material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with Examples 1-6.

[0104] Examples 62-67

[0105] By using SIS instead of TPEE as the polymer support material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with Examples 1-6.

[0106] Examples 68-73

[0107] By using SBS instead of TPEE as the polymer support material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with Examples 1-6.

[0108] Examples 74-79

[0109] By using SEBS instead of TPEE as the polymer support material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with Examples 1-6.

[0110] Examples 80-85

[0111] By using SEPS instead of TPEE as the polymer support material, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with Examples 1-6.

[0112] Examples 86-91

[0113] Carbon nanotubes were used instead of expanded graphite as a thermally conductive additive to obtain a corresponding thermotropic flexible composite phase change material, with other conditions consistent with those in Examples 1-6.

[0114] Examples 92-97

[0115] By using carboxylated carbon nanotubes instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0116] Examples 98-103

[0117] By using graphene instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0118] Examples 104-109

[0119] By using graphene oxide instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0120] Examples 110-115

[0121] Carbon nanotubes were used instead of expanded graphite as a thermally conductive additive to obtain a corresponding thermotropic flexible composite phase change material, with other conditions consistent with those in Examples 1-6.

[0122] Examples 116-121

[0123] By using titanium dioxide instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0124] Examples 122-127

[0125] By using alumina instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0126] Examples 128-133

[0127] By using zinc oxide instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with Examples 1-6.

[0128] Examples 134-139

[0129] By using nano-silver instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0130] Examples 140-145

[0131] By using nano-copper instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0132] Examples 146-151

[0133] By using nano-gold instead of expanded graphite as a thermally conductive additive, a corresponding thermotropic flexible composite phase change material was obtained, with other conditions consistent with those in Examples 1-6.

[0134] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermotropic flexible composite phase change material coupled with a multi-crosslinked network aerogel material, characterized in that: The mass percentages of each component in the thermotropic flexible composite phase change material coupled with a multi-crosslinked network aerogel material are as follows: Multi-crosslinked network aerogel: 0.5~1.5wt% Thermotropic flexible composite phase change material: 96.5~97.5 wt%; Adhesive: 1~3wt%; A binder is used to bond a multi-crosslinked network aerogel and a thermotropic flexible composite phase change material together. The mass percentage of each component in the multi-crosslinked network aerogel material is as follows: Gelatin: 50%~70wt%; Sodium alginate: 29~49 wt%; Crosslinking agent boric acid: 0.5~3wt%; Crosslinking agent glutaraldehyde: 0.5~3wt%; The multi-crosslinked network aerogel is formed by crosslinking a dual crosslinking agent with gelatin and sodium alginate to create a stable multi-network structure. The mass percentage of each component in the thermotropic flexible composite phase change material is as follows: Inorganic solid-liquid phase change materials: 72~82wt% Thermal conductivity enhancer: 1.0~2.0wt%; Polymer support material: 17~27wt%.

2. The thermotropic flexible composite phase change material coupled with a multi-crosslinked network aerogel material according to claim 1, characterized in that: The inorganic solid-liquid phase change material is one to three of the following: sodium acetate trihydrate, calcium sulfate dihydrate, potassium aluminum sulfate dodecahydrate, ammonium aluminum sulfate dodecahydrate, magnesium chloride hexahydrate, magnesium sulfate heptahydrate, calcium nitrate tetrahydrate, zinc chloride hexahydrate, and sodium thiosulfate pentahydrate.

3. The thermotropic flexible composite phase change material coupled with a multi-crosslinked network aerogel material according to claim 1, characterized in that: The thermal conductivity enhancer is one to three of the following: expanded graphite, carbon nanotubes, carboxylated carbon nanotubes, graphene, graphene oxide, titanium dioxide, aluminum oxide, zinc oxide, sodium chloride, nano-silver, nano-copper, and nano-gold.

4. The thermotropic flexible composite phase change material coupled with a multi-crosslinked network aerogel according to claim 1, characterized in that: The polymer support material is one to three of the following: styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butene-styrene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer, and thermoplastic polyester elastomer.

5. A method for preparing a thermotropic flexible composite phase change material coupled with a multi-crosslinked network aerogel material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Mix gelatin and sodium alginate, stir and heat to dissolve in acetic acid solution; Then, add boric acid, stir, and then add glutaraldehyde solution; After stirring together, the resulting solution is placed into a mold, then frozen, and finally freeze-dried in a freeze dryer to obtain a multi-crosslinked network aerogel. (2) Dissolve the polymer support material in a solvent until it is uniformly dissolved; Secondly, the inorganic solid-liquid phase change material is heated to a liquid state, and a thermal conductivity enhancer is added to it for adsorption. Then, it is crushed using a ball mill and added to a polymer support material solution for mixing and adsorption. The solvent is removed to obtain a thermotropic flexible composite phase change material. (3) Apply the adhesive to the surface of the thermo-flexible composite phase change material, and then place the multi-crosslinked network aerogel on the surface of the thermo-flexible composite phase change material and cure at room temperature to obtain the thermo-flexible composite phase change material coupled with the multi-crosslinked network aerogel.

6. The preparation method of the thermotropic flexible composite phase change material and the multi-crosslinked network aerogel coupling material according to claim 5, characterized in that: The solvent is one to three of the following: tetrahydrofuran, dioxane, petroleum ether, acetone, butanone, chloroform, dichloromethane, carbon tetrachloride, carbon disulfide, dimethylformamide, dimethyl sulfoxide, benzene, toluene, xylene, nitrobenzene, chlorobenzene, cyclohexane, or n-hexane.

7. The application of the thermotropic flexible composite phase change material according to any one of claims 1-4 and the multi-crosslinked network aerogel coupling material, characterized in that: The material is used in the thermal protection of buildings, batteries, and electronic devices.

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