CN111849423A - Ionic crosslinked hybrid graphene aerogel phase-change composite material and preparation thereof - Google Patents
Ionic crosslinked hybrid graphene aerogel phase-change composite material and preparation thereof Download PDFInfo
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Abstract
The invention relates to an ion-crosslinked hybrid graphene aerogel phase-change composite material and a preparation method thereof. The preparation method specifically comprises the following steps: (a) mixing the graphene oxide solution with the expanded graphite, adding the cross-linking material solution, mixing, and performing hydrothermal reaction to obtain a mixed graphene hydrogel; (b) freeze-drying the hybrid graphene hydrogel to obtain hybrid graphene aerogel; (c) and putting the hybrid graphene aerogel into a molten phase-change material, and naturally cooling after the phase-change material is adsorbed to saturation to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material. Compared with the prior art, the network structure of the phase-change composite material is more compact, and the phase-change composite material is favorable for better transfer of heat energy in an aerogel network.
Description
Technical Field
The invention belongs to the technical field of phase change energy storage and heat conduction, and particularly relates to an ionic crosslinked hybrid graphene aerogel phase change composite material and a preparation method thereof.
Background
In recent years, the increasing problems of energy depletion and environmental pollution have led to the concern about the storage and recovery of renewable energy. The heat storage materials are classified into three types according to the heat storage mode: sensible heat storage materials, thermochemical heat storage materials and latent heat storage materials.
Sensible heat storage materials are materials that store or release energy by absorbing or releasing energy in a phase state, and have the advantages of wide sources and low cost, however, such materials have many disadvantages, such as: the heat storage density is low, the constant temperature cannot be kept in the heat release process, and when the temperature is different from the ambient temperature, the heat loss is easy to occur, so that the material is not suitable for storing heat with high efficiency for a long time, and the application range is small.
Thermochemical heat storage is to store and release heat by utilizing reversible chemical reaction, and thermochemical heat storage has higher heat storage density and heat storage efficiency, but because the chemical reaction process is more complicated and difficult to control, the research on thermochemical heat storage is still in the primary stage at present, and a long way is left for practical application.
Latent heat storage materials, also known as Phase Change Materials (PCMs), store and release energy using energy absorbed or released when a substance is transformed in a different phase. Compared with a sensible heat energy storage material, the latent heat energy storage material has higher heat storage density, and the temperature of the phase change material is almost kept unchanged when the phase change occurs, so that the latent heat energy storage material has a wide application prospect. The phase change material has the following advantages: (1) higher heat storage density; (2) the volume change is small in the phase change process; (3) the stability is good, and no rapid temperature change occurs in the phase change process; (4) can be recycled, etc. However, phase change materials also have some disadvantages: for example, the phase change material has low thermal conductivity and is easy to leak in the phase change process.
In view of the disadvantage of low thermal conductivity of phase change materials, it is common to incorporate thermally conductive fillers such as metals (copper, nickel and aluminum) or carbon-based (carbon, graphite and expanded graphite) porous materials/foams in phase change materials. Among them, carbon materials are most widely used. Since the true densities of different types of carbon materials are not greatly different, each carbon material has advantages in practical applications. Expanded Graphite (EG) is made from natural flake graphite and exhibits better thermal properties than flake graphite. The graphene has a net structure and high thermal conductivity. The thermal conductivity of the material can be improved by the hybrid graphene aerogel prepared by the expanded graphite and the graphene through a hydrothermal method, and the porous structure of the aerogel is favorable for adsorption of the phase-change material. However, the two materials have loose structures and hinder the heat transfer in the three-dimensional inner space to a certain extent.
Disclosure of Invention
The invention aims to provide an ion-crosslinked hybrid graphene aerogel phase-change composite material and a preparation method thereof, wherein the network structure of the phase-change composite material is more compact, and heat energy can be better transferred in an aerogel network.
The purpose of the invention is realized by the following technical scheme:
the utility model provides an ionic crosslinking's hybrid graphene aerogel phase change composite, phase change composite contains heat conduction filler material, phase change material and cross-linking material, heat conduction filler material is hybrid graphene aerogel, hybrid graphene aerogel comprises oxidation graphite alkene and expanded graphite.
In the hybrid graphene aerogel, the mass fraction of the expanded graphite is 50-70%, preferably 60%.
The phase change material is paraffin.
The crosslinking material is a metal chloride salt.
The metal chloride is selected from KCl and MgCl2Or FeCl3One or more of (a).
The metal chloride is MgCl2。
The volume of the ion-crosslinked hybrid graphene aerogel phase-change composite material is 4.5cm3，MgCl2The content of the ionic crosslinked phase-change composite material in the ionic crosslinked phase-change composite material is 0.0089-0.053 mmol/cm3Specifically, MgCl2The content in the ion-crosslinked phase-change composite material is 0.0089mmol/cm3、0.018mmol/cm3、0.036mmol/cm3、0.044mmol/cm3And 0.053mmol/cm3Preferably 0.044mmol/cm3。
The addition ratio of the heat-conducting filling material to the crosslinking material is 1g (0.02-0.4) mmol. When the crosslinking material is KCl, the addition ratio of the heat-conducting filling material to the crosslinking material is 1g (0.16-0.4) mmol, preferably 1g (0.16-0.32) mmol, and more preferably 1g:0.32 mmol; when cross-linkedThe material is MgCl2In the case of the method, the addition ratio of the heat-conducting filling material to the crosslinking material is 1g (0.04-0.24) mmol, preferably 1g (0.04-0.2) mmol, and more preferably 1g:0.2 mmol; when the crosslinking material is FeCl3In the case of the heat conductive filler and the crosslinking material, the addition ratio of the heat conductive filler to the crosslinking material is 1g (0.02 to 0.2) mmol, preferably 1g (0.02 to 0.08) mmol, and more preferably 1g:0.08 mmol.
The addition ratio of the heat conduction filling material, the phase change material and the crosslinking material is 1g (10.5-13.7 g) to 0.02-0.4 mmol, and preferably 1g (11.17-13.00 g) to 0.02-0.4 mmol.
A preparation method of the graphene aerogel phase change composite material specifically comprises the following steps:
(a) mixing the graphene oxide solution with the expanded graphite, adding the crosslinking material solution, mixing, and performing hydrothermal reaction to obtain the ionic crosslinked hybrid graphene hydrogel;
(b) freeze-drying the ion-crosslinked hybrid graphene hydrogel obtained in the step (a) to obtain an ion-crosslinked hybrid graphene aerogel;
(c) and (c) putting the ion-crosslinked hybrid graphene aerogel obtained in the step (b) into a molten phase-change material, and naturally cooling after the phase-change material is adsorbed to saturation to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material.
In the step (a), the graphene oxide solution is prepared by an improved Hummer method, the concentration of graphene oxide in the graphene oxide solution is 8-12 mg/ml, preferably 10mg/ml, and the graphene oxide solution is diluted to 8-12 mg/ml.
In the step (a), the hydrothermal reaction is carried out in a reaction kettle, the reaction kettle is placed in a vacuum drying oven, the temperature of the vacuum drying oven is 160-200 ℃, 180 ℃ is preferred, and the reaction time is 15-19 hours, 17 hours is preferred.
In the step (a), the concentration of the crosslinking material solution is 20-400 mM. The volume of the crosslinking material solution is 1ml, the crosslinking material solution is a metal chloride solution, and when the metal chloride is KCl, the concentration of the solution can be set to 160mM, 200mM, 240mM, 320mM,400 mM; when the metal chloride salt is MgCl2When the concentration of the solution is 40mM, 80mM, 160mM, 200mM, 240 mM; when the metal chloride is FeCl3In this case, the concentration of the solution may be set to 20mM, 40mM, 80mM, 160mM, 200 mM. Preferably, the crosslinking material solution is MgCl with a concentration of 200mM2And (3) solution.
In the step (b), freeze-drying is carried out under vacuum condition, the freeze-drying temperature is-70-0 ℃, preferably-50 ℃, and the freeze-drying time is 22-26 h, preferably 24 h.
In the step (c), the ion-crosslinked hybrid graphene aerogel is firstly cut into pieces with the thickness of 2-8 cm (preferably 5cm, and the volume of 4.5 cm)3) And then put into the melted phase change material. The technological parameters such as the vacuum drying temperature, the freeze-drying temperature, the time and the like have important influence on the preparation of the ion-crosslinked rGO/EG mixed hydrogel with the three-dimensional (3D) structure and the ion-crosslinked rGO/EG mixed aerogel with the three-dimensional (3D) structure. Firstly, the hydrothermal reaction is mainly a process in which chemical reactions occur in the cross-linking between GO. Research shows that the most reasonable temperature for chemical reaction of GO is 150-200 ℃, if the high-temperature reaction time is not controlled, the GO cross-linking reaction is incomplete, and the reduction degree cannot reach the preparation of the complete rGO/EG mixed hydrogel. Secondly, the large amount of water in the rGO/EG hybrid hydrogel occupies a large mass, and the water must be removed, and it is the space left after the water removal that provides the three-dimensional porous structure of the rGO/EG hybrid aerogel. The invention adopts a vacuum sublimation method to remove water, and the water can be fully removed only by setting the freeze-drying temperature and the freeze-drying time within a specific range, thereby forming a required uniform porous structure.
According to the invention, metal chloride (KCl, MgCl) with different valence states is added into the hybrid graphene aerogel2And FeCl3) Through the complexation of the metal ions and the graphene functional groups, the cross-linking capacity of the hybrid graphene is improved, so that heat can be better transferred in the material, and the thermal conductivity of the phase-change composite material is greatly improved. The three-dimensional grid structure enables the rGO/EG aerogel to become a stable framework, and the shape of the phase-change composite material is still kept even under the conditions of high paraffin content and large latent heatStability of the shape.
Firstly, mixed graphite alkene aerogel comprises oxidation graphite alkene and expanded graphite, as heat conduction filler material, and wherein, oxidation graphite alkene has the space network structure, can make the better transmission of heat in the material is inside, and expanded graphite has the porosity, and its three-dimensional structure is not only good heat conduction network, and porous structure does benefit to more moreover and adsorbs phase change material. The graphene oxide mainly comprises two parts, namely an oxidized region (hydrophilic region) and an unoxidized region (hydrophobic region), and can be regarded as a product obtained by modifying the inside and the edge of a graphene sheet layer by oxygen-containing functional groups (mainly comprising hydroxyl, carboxyl, epoxy and the like), and the special structure enables the graphene oxide to be regarded as a two-dimensional polymer, an anisotropic colloid, an amphiphilic substance and the like. When expanded graphite mixes with graphite oxide, because expanded graphite has the hydrophobicity, consequently graphite oxide's hydrophobic end and expanded graphite contact, hydrophilic end and aqueous solution contact to form comparatively stable graphite oxide expanded graphite mixed suspension, the graphite alkene aerogel has excellent heat conductivity, can be used for improving phase change material thermal conductivity. The expanded graphite has porosity, and the expanded graphite with a three-dimensional structure not only has a good heat conducting network, but also has the porosity which is more beneficial to adsorbing the phase-change material.
Secondly, the cross-linking material is metal chloride, and the heat cannot be well transferred in the material due to the loose structure of the hybrid graphene aerogel. The metal ions can be complexed with functional groups of the graphene, so that the graphene which is originally distributed in a layered manner is tightly bonded and crosslinked, and the thermal conductivity of the phase-change composite material is increased. The thermal conductivity of the hybrid graphene aerogel phase-change composite material doped with the three metal chlorides is measured by a steady-state flat plate method, and the fact that the thermal conductivity is increased at a higher speed with the increase of the valence state of the metal ions is found, that is, the higher the ionic valence state is, the higher the crosslinking efficiency of the three-dimensional network structure is. In addition, the thermal conductivity of the phase-change composite material tends to increase and decrease along with the increase of the concentration of the doped metal chloride. In the initial stage of reaction, due to the cross-linking effect of metal ions, the three-dimensional network structure is more compact, which is favorable for better heat transfer in the network space, thereby improving the heat conduction of the network spaceAnd (4) performance. However, when metal ions are excessively doped, the original three-dimensional network structure is damaged, and the mixed graphene aerogel structure is looser and not beneficial to heat energy transfer, so that the heat conductivity of the phase-change composite material is reduced. Comparing the maximum values of thermal conductivity at different concentrations of the three ions, it was found that 1ml of MgCl with a concentration of 200mM was incorporated in 1g of hybrid graphene aerogel2In the process, the crosslinking degree of the graphene aerogel is highest, and the thermal conductivity reaches 0.56 W.m-1·K-1. MgCl without taking into account the rate of enhancement of thermal conductivity by ionic concentration2The phase change composite material has the best effect of improving the heat conduction of the phase change composite material.
Finally, since no chemical reaction occurs between the hybrid graphene aerogel and the paraffin, and only physical bonding occurs, the oxygen-containing functional groups in the graphene oxide structure promote heterogeneous crystallization of the paraffin, which increases the phase change latent heat of the paraffin.
Compared with the prior art, the beneficial effects of the invention are embodied in the following aspects:
(1) the invention discloses a preparation method of an ionic crosslinked three-dimensional reticular graphene phase change composite material for the first time, and greatly widens the application of the phase change material in the fields of temperature control and heat management and energy storage.
(2) Compared with the traditional phase change material, the ionic crosslinking phase change composite material prepared by the method has excellent heat-conducting property and packaging capacity. The metal ions can promote the hybrid graphene aerogel to be crosslinked, so that the three-dimensional network structure of the aerogel is more compact, and heat energy can be better transferred in the aerogel network. Within a certain range, the higher the metallic ion valence state is, the higher the thermal conductivity is, i.e. the higher the ionic valence state is, the higher the crosslinking efficiency of the three-dimensional network structure is. The thermal conductivity is improved to different degrees (to 0.42-0.56 W.m) along with the increase of the ion concentration-1·K-1). Wherein the divalent magnesium metal ions have the best crosslinking effect on the hybrid graphene aerogel.
Drawings
FIG. 1 is a flow chart of the preparation of a phase change composite;
fig. 2 is a scanning electron micrograph of the hybrid graphene aerogels prepared in example 3 and comparative example 1 (a is comparative example 1, and b is example 3);
fig. 3 is a graph comparing infrared spectra of the hybrid graphene aerogels prepared in examples 2, 6, and 7 and comparative example 1;
FIG. 4 is a graph of the thermal conductivity of phase change composites made with different concentrations and different metal ions in examples 1-15 and comparative example 1;
FIG. 5 is a graph showing the thermal conductivity enhancement rate per ion concentration for the phase change composites prepared in examples 1-15 using different concentrations and different metal ions.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
The paraffin used by the invention is provided by the national drug group chemical reagent company Limited, and has the specification of chemical purity, the melting point of 48-52 ℃ and the density of 0.86g/cm3. Natural flake graphite of 200 mesh was purchased from shanghai monosail graphite products ltd. Expanded Graphite (EG) is supplied by Hebei Baoding Shuixing cemented carbide Co., Ltd, and has an expansion rate of 150ml/g and an average particle diameter before expansion of 0.18 mm.
Example 1
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method, and the preparation process is specifically shown in figure 1:
(1) graphene Oxide (GO) is prepared by oxidizing natural graphite powder according to an improved Hummers method, and a graphene oxide solution with the concentration of 10mg/ml is obtained after dilution (the concentration of doped graphene oxide aerogel is generally 8 mg/ml-12 mg/ml, and the concentration is the concentration measured by dilution and drying test after the preparation of the graphene oxide solution, and the same is carried out below).
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are respectively added into a beaker and stirred uniformly.
(3) 1ml of MgCl with a concentration of 40mM was added to the beaker2Solution (MgCl)2The solution is prepared by magnesium chloride hexahydrate, and examples 2, 3, 4 and 5 are the same), and the mixture is uniformly stirred to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The ion-crosslinked rGO/EG hybrid aerogel was cut into 5mm thick wafers (the thickness of the wafers was 1/5 for the ion-crosslinked rGO/EG hybrid aerogel prepared in step (5), i.e., the wafers contained thermal conductive filler and crosslinking material both in mass of 1/5 for the ion-crosslinked rGO/EG hybrid aerogel, the same applies below) and had a volume of about 4.5cm3And putting the composite material into completely melted paraffin (the paraffin is melted in a 70-100 ℃ water bath in advance, the same applies below), quickly adsorbing the paraffin by the ion-crosslinked rGO/EG mixed aerogel, taking out the paraffin after the paraffin is adsorbed to saturation, and naturally cooling to obtain the ion-crosslinked mixed graphene aerogel phase-change composite material with the mass of 2.4792 g. The thermal conductivity of the phase-change composite material measured by the steady-state flat plate method is 0.42 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows the relationship between the thermal conductivity enhancement rate per ion concentration and the specific value of 1.25 L.mmol-1。
Example 2
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 10 mg/ml.
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are respectively added into a beaker and stirred uniformly.
(3) 1ml MgCl with a concentration of 80mM is added into different beakers2And stirring the solution uniformly to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The ion-crosslinked rGO/EG hybrid aerogel was cut into 5mm thick wafers having a volume of about 4.5cm3And putting the composite material into completely melted paraffin, quickly adsorbing paraffin by the ion-crosslinked rGO/EG mixed aerogel, taking out the paraffin after the paraffin is adsorbed to saturation, and naturally cooling to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material with the mass of 2.5134 g.
The infrared spectrum of the phase-change composite material is shown in FIG. 3, and can be seen, 1725cm-1Stretching of C ═ O in the carboxyl function occurs; 1450cm-1、1536cm-1The position corresponds to an absorption peak of a benzene ring framework; 1382cm-1Corresponds to a C-OH absorption peak; 1186cm-1The corresponding point is the absorption peak of C-O-C stretching vibration in epoxide; 1040cm-1The position is a C-O stretching vibration absorption peak. The doping of the metal chloride enables the phase-change composite material to generate a new absorption peak in a low wave band, such as 616cm-1Mg of (2)2+and-OH generation peaks. And a new C-O stretching vibration absorption peak and a C-OH absorption peak appear, which are generated by the ring opening of the epoxide in the graphene caused by the doping of the metal ions. And the absorption peak intensity of carboxyl C-O is increased to different degrees, which provides possibility for coordination of metal ions and graphene oxide functional groups. And incorporation of K+、Fe3+Except that Mg is doped2+The absorption peak intensity of C ═ O and carboxyl C-O in the time-infrared spectrum is obviously increased, and the peak position is also changed, respectively 1637cm-1And 1110cm-1，This is because the carboxylic acid coordinates to the metal ion to cause a red shiftSuch as a mouse. On the other hand, Mg2+Are embedded into the gaps between the graphite oxide sheets to enable the graphene sheets to be cross-linked together, and the carbon chain tends to be lengthened and ordered at 721cm-1The absorption peak of the long-chain carbon chain appears. Of the three ions, only Mg2+There is this phenomenon, so among the three ions, divalent Mg2+The cross-linking degree of the hybrid graphene aerogel is improved to be superior to that of other two ions.
The thermal conductivity of the phase-change composite material measured by a steady-state flat plate method is 0.45 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows the relationship between the thermal conductivity enhancement rate per ion concentration and the specific value of 1.6 L.mmol-1。
Example 3
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 10 mg/ml.
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are added into a beaker respectively, and the expanded graphite accounts for 60% of the total mass of EG and GO and is stirred uniformly.
(3) 1ml MgCl with a concentration of 160mM is added into different beakers2And stirring the solution uniformly to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The ion-crosslinked rGO/EG hybrid aerogel was cut into 5mm thick wafers having a volume of about4.5cm3And putting the graphene into completely melted paraffin, quickly adsorbing the paraffin by the rGO/EG mixed aerogel, taking out the paraffin after the paraffin is adsorbed to saturation, and naturally cooling to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material with the mass of 2.5572 g. In this embodiment, the scanning electron microscope image of the rGO/EG mixed aerogel obtained in step (4) is shown in fig. 2b, and it can be seen that the graphene aerogel mixed with ions generates a cross-linking phenomenon and is wrapped together in a sheet shape, thereby forming a relatively compact structure. The thermal conductivity of the phase change composite material measured by the steady state plate method is 0.51 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows the relationship between the thermal conductivity enhancement rate per ion concentration and the value of 1.7 L.mmol-1。
Example 4
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 10 mg/ml.
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are added into a beaker respectively, and the expanded graphite accounts for 60% of the total mass of EG and GO and is stirred uniformly.
(3) 1ml MgCl with a concentration of 200mM is added into different beakers2And stirring the solution uniformly to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) Cutting the ion-crosslinked rGO/EG mixed aerogel into round cakes with the thickness of 5mm,the volume is about 4.5cm3And putting the graphene into completely melted paraffin, quickly adsorbing the paraffin by the rGO/EG mixed aerogel, taking out the paraffin after the paraffin is adsorbed to saturation, and naturally cooling to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material with the mass of 2.6121 g. The thermal conductivity of the phase-change composite material measured by the steady-state flat plate method is 0.56 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate per ion concentration of 2.0 L.mmol-1。
Example 5
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 10 mg/ml.
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are added into a beaker respectively, and the expanded graphite accounts for 60% of the total mass of EG and GO and is stirred uniformly.
(3) 1ml MgCl with a concentration of 240mM is added into different beakers respectively2And stirring the solution uniformly to form a mixed solution.
(4) Transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the ion-crosslinked graphene expanded graphite mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The ion-crosslinked rGO/EG hybrid aerogel was cut into 5mm thick wafers having a volume of about 4.5cm3Putting the graphene into completely melted paraffin, quickly adsorbing the paraffin by the rGO/EG mixed aerogel, taking out the paraffin after the paraffin is adsorbed to saturation, and naturally cooling to obtain the ion-crosslinked mixed grapheneThe aerogel phase change composite material has the mass of 2.6116 g. The thermal conductivity of the phase-change composite material measured by a steady-state flat plate method is 0.548 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows the relationship between the thermal conductivity enhancement rate per ion concentration and the specific value of 1.5 L.mmol-1。
Example 6
The utility model provides an ionic crosslinking mixes graphite alkene aerogel phase transition combined material, contains heat conduction filler material, phase transition material and cross-linking material, and heat conduction filler material is mixed graphite alkene aerogel, and mixed graphite alkene aerogel comprises oxidation graphite alkene and expanded graphite, and the cross-linking material is KCl, and the phase transition material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 10 mg/ml.
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are added into a beaker respectively, and the expanded graphite accounts for 60% of the total mass of EG and GO and is stirred uniformly.
(3) 1ml of KCl solution with the concentration of 320mM is added into different beakers respectively and stirred uniformly to form mixed solutions.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The ion-crosslinked rGO/EG hybrid aerogel was cut into 5mm thick wafers having a volume of about 4.5cm3And putting the graphene into completely melted paraffin, quickly adsorbing the paraffin by the rGO/EG mixed aerogel, taking out the paraffin after the paraffin is adsorbed to saturation, and naturally cooling to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material with the mass of 2.7101 g. The infrared spectrum of the phase change composite material is shown in FIG. 3, and it can be seen that K is doped+Roughly consistent with the infrared profile of the undoped metal ions. The phase-change composite material is measured by a steady-state flat plate methodThe thermal conductivity obtained was 0.54 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate at a unit ion concentration of 0.7L mmol-1。
Example 7
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is a hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is FeCl3The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 10 mg/ml.
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are added into a beaker respectively, and the expanded graphite accounts for 60% of the total mass of EG and GO and is stirred uniformly.
(3) 1ml of FeCl with a concentration of 80mM is added into different beakers3Solution (FeCl)3The solution was prepared using ferric chloride hexahydrate, the same as in examples 12, 13, 14, and 15), and stirred uniformly to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The ion-crosslinked rGO/EG hybrid aerogel was cut into 5mm thick wafers having a volume of about 4.5cm3And putting the graphene into completely melted paraffin, quickly adsorbing the paraffin by the rGO/EG mixed aerogel, taking out the paraffin after the paraffin is adsorbed to saturation, and naturally cooling to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material with the mass of 2.6669 g. The infrared spectrum of the phase change composite material is shown in FIG. 3, and it can be seen that Fe is doped3+Roughly consistent with the infrared profile of the undoped metal ions. The phase change compositeThe thermal conductivity of the material measured by the stationary plate method is 0.5 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate per ion concentration of 0.9L mmol-1。
Example 8
The utility model provides an ionic crosslinking mixes graphite alkene aerogel phase transition combined material, contains heat conduction filler material, phase transition material and cross-linking material, and heat conduction filler material is mixed graphite alkene aerogel, and mixed graphite alkene aerogel comprises oxidation graphite alkene and expanded graphite, and the cross-linking material is KCl, and the phase transition material is paraffin. The phase change composite material was prepared by the following preparation method, except that the concentration of the added KCl solution was 160mM, the rest was the same as in example 6, and finally the ion-crosslinked hybrid graphene aerogel phase change composite material was obtained, with a mass of 2.6987 g. The thermal conductivity of the phase-change composite material measured by the steady-state flat plate method is 0.44 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate per ion concentration of 2.5 L.mmol-1。
Example 9
The utility model provides an ionic crosslinking mixes graphite alkene aerogel phase transition combined material, contains heat conduction filler material, phase transition material and cross-linking material, and heat conduction filler material is mixed graphite alkene aerogel, and mixed graphite alkene aerogel comprises oxidation graphite alkene and expanded graphite, and the cross-linking material is KCl, and the phase transition material is paraffin. The phase change composite material was prepared by the following preparation method, except that the concentration of the added KCl solution was 200mM, the rest was the same as in example 6, and finally the ion-crosslinked hybrid graphene aerogel phase change composite material was obtained, with a mass of 2.6908 g. The thermal conductivity of the phase-change composite material measured by a steady-state flat plate method is 0.467 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate per ion concentration of 4.4 L.mmol-1。
Example 10
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid grapheneThe aerogel is prepared from graphene oxide and expanded graphite, the crosslinking material is KCl, and the phase-change material is paraffin. The phase change composite material was prepared by the following preparation method, the same as example 6 except that the concentration of the added KCl solution was 240mM, and finally the ion-crosslinked hybrid graphene aerogel phase change composite material was obtained, having a mass of 2.7023 g. The thermal conductivity of the phase-change composite material measured by the steady-state flat plate method is 0.49 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows the relationship between the thermal conductivity enhancement rate per ion concentration and the specific value of 3.1 L.mmol-1。
Example 11
The utility model provides an ionic crosslinking mixes graphite alkene aerogel phase transition combined material, contains heat conduction filler material, phase transition material and cross-linking material, and heat conduction filler material is mixed graphite alkene aerogel, and mixed graphite alkene aerogel comprises oxidation graphite alkene and expanded graphite, and the cross-linking material is KCl, and the phase transition material is paraffin. The phase change composite material was prepared by the following preparation method, except that the concentration of the added KCl solution was 400mM, the rest was the same as in example 6, and finally the ion-crosslinked hybrid graphene aerogel phase change composite material was obtained, with a mass of 2.6908 g. The thermal conductivity of the phase-change composite material measured by the steady-state plate method is 0.53 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate at a unit ion concentration of 0.6 L.mmol-1。
Example 12
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is a hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is FeCl3The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method except for adding FeCl3The solution concentration was 20mM, the rest was the same as in example 7, and finally an ion-crosslinked hybrid graphene aerogel phase change composite material was obtained, having a mass of 2.5062 g. The phase-change composite material has thermal conductivity measured by a steady-state flat plate methodAs shown in FIG. 4, it was 0.42 W.m-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate at a unit ion concentration of 0.6 L.mmol-1。
Example 13
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is a hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is FeCl3The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method except for adding FeCl3The solution concentration was 40mM, and the rest was the same as in example 7, and finally an ion-crosslinked hybrid graphene aerogel phase-change composite material having a mass of 2.4345g was obtained. The thermal conductivity of the phase-change composite material measured by the steady-state flat plate method is 0.47 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows the relationship between the thermal conductivity enhancement rate per ion concentration and the value of 0.8 L.mmol-1。
Example 14
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is a hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is FeCl3The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method except for adding FeCl3The solution concentration was 160mM and the rest was the same as in example 7, and finally an ion-crosslinked hybrid graphene aerogel phase change composite material having a mass of 2.5234g was obtained. The thermal conductivity of the phase-change composite material measured by a steady-state flat plate method is 0.45 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows the relationship between the thermal conductivity enhancement rate per ion concentration and the specific value of 1.1 L.mmol-1。
Example 15
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is a hybrid materialThe graphene aerogel is mixed with the graphene aerogel and consists of graphene oxide and expanded graphite, and the cross-linking material is FeCl3The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method except for adding FeCl3The solution concentration was 200mM, the rest was the same as in example 7, and finally an ion-crosslinked hybrid graphene aerogel phase-change composite material having a mass of 2.7991g was obtained. The thermal conductivity of the phase-change composite material measured by a steady-state flat plate method is 0.45 W.m, as shown in FIG. 4-1·K-1FIG. 5 shows a graph of the thermal conductivity enhancement rate at a unit ion concentration of 0.7L mmol-1。
Fig. 4 is a graph of thermal conductivity measured by the stationary plate method for examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and comparative example 1. By comparing the thermal conductivity obtained by the doping of metal ions and the doping without metal ions, it can be found that the thermal conductivity of the phase-change composite material can be increased after the metal ions are doped, and the thermal conductivity can be increased from 0.40 W.m-1·K-1Increased to 0.56 W.m-1·K-1The increase is 40%. In addition, it can be seen that the thermal conductivity of the phase-change composite material shows a tendency of increasing first and then decreasing as the concentration of the metal ions increases. This is because when the metal ions are excessively doped, the original three-dimensional network structure is destroyed, which is disadvantageous to the thermal energy transfer, thereby reducing the thermal conductivity thereof. Comparing the maximum thermal conductivity of the three ions at different concentrations, it was found that MgCl was incorporated2The mixed graphene aerogel with the doping amount of 0.2mmol/1g has the best effect of improving the thermal conductivity of the phase-change composite material, and the thermal conductivity reaches 0.56 W.m at most-1·K-1。
Fig. 5 is a graph showing the thermal conductivity enhancement rate per ion concentration for examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15. The thermal conductivity enhancement rate per ion concentration is expressed as follows:
wherein eta represents the thermal conductivity enhancement rate (in L/m) per ion concentrationol)，λ1Representative of thermal conductivity (in W.m) of ionically crosslinked hybrid graphene phase change composite materials-1·K-1)，λ0Represents the thermal conductivity (unit is W.m) of the hybrid graphene phase-change composite material without doped ions-1·K-1) And C represents the concentration of the doped metal ions (unit is mol/L). It can be seen from the figure that as the valence state of the metal ions increases, the thermal conductivity enhancement rate per unit ion concentration of the phase-change composite material is higher, and the crosslinking efficiency of the three-dimensional network structure is higher. However, when the concentration of the metal ions to be doped reaches a certain value, the thermal conductivity enhancement rate per ion concentration decreases as the concentration of the metal ions to be doped increases.
Example 16
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 8 mg/ml.
(2) Respectively adding 75ml of graphene oxide solution and 0.6g of expanded graphite into a beaker, and uniformly stirring, wherein the mass ratio of the graphene oxide to the expanded graphite is 5: 5.
(3) 1ml MgCl was added to the beaker at a concentration of 200mM2And stirring the solution uniformly to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction at 160 ℃ for 19 hours to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 22h at the temperature of-50 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The method comprises the steps of cutting the ion-crosslinked rGO/EG mixed aerogel into round cakes with the thickness of 2mm, putting the round cakes into completely-melted paraffin, enabling the rGO/EG mixed aerogel to rapidly adsorb the paraffin, taking out the paraffin when the paraffin is adsorbed to saturation, and naturally cooling the paraffin to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material.
Example 17
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2The phase change material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method, and a graphene oxide solution was obtained with a concentration of 12 mg/ml.
(2) And respectively adding 21.4ml of graphene oxide solution and 0.6g of expanded graphite into a beaker, and uniformly stirring, wherein the mass ratio of the graphene oxide to the expanded graphite is 3: 7.
(3) 1ml MgCl was added to the beaker at a concentration of 200mM2And stirring the solution uniformly to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction at 200 ℃ for 15 hours to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) placing the hydrogel in a freeze dryer for vacuum freeze-drying for 26h at the temperature of 0 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The method comprises the steps of cutting the ion-crosslinked rGO/EG mixed aerogel into a round cake with the thickness of 8mm, putting the round cake into completely-melted paraffin, enabling the rGO/EG mixed aerogel to rapidly adsorb the paraffin, taking out the paraffin when the paraffin is adsorbed to saturation, and naturally cooling the paraffin to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material.
Example 18
The ion-crosslinked hybrid graphene aerogel phase-change composite material comprises a heat-conducting filling material, a phase-change material and a crosslinking material, wherein the heat-conducting filling material is hybrid graphene aerogel, the hybrid graphene aerogel consists of graphene oxide and expanded graphite, and the crosslinking material is MgCl2Phase of changeThe variable material is paraffin. The phase-change composite material is prepared by the following preparation method:
(1) graphene Oxide (GO) was prepared by oxidizing natural graphite powder according to the modified Hummers method and a graphene oxide solution was obtained with a concentration of 9 mg/ml.
(2) 40ml of graphene oxide solution and 0.6g of expanded graphite are respectively added into a beaker, and the mixture is stirred uniformly.
(3) 1ml MgCl was added to the beaker at a concentration of 200mM2And stirring the solution uniformly to form a mixed solution.
(4) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 16 hours at 190 ℃ to obtain the ion-crosslinked rGO/EG mixed hydrogel.
(5) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-70 ℃ to obtain the ion-crosslinked rGO/EG mixed aerogel.
(6) The method comprises the steps of cutting the ion-crosslinked rGO/EG mixed aerogel into a round cake with the thickness of 8mm, putting the round cake into completely-melted paraffin, enabling the rGO/EG mixed aerogel to rapidly adsorb the paraffin, taking out the paraffin when the paraffin is adsorbed to saturation, and naturally cooling the paraffin to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material.
Comparative example 1
An existing ion-free cross-linked hybrid graphene aerogel phase-change composite material is prepared by the following preparation method:
(1) according to an improved Hummers method, Graphene Oxide (GO) is prepared by oxidizing natural graphite powder, and a graphene oxide solution of 10mg/ml is obtained after dilution.
(2) 40ml of graphene oxide and 0.6g of expanded graphite are added into a beaker respectively, and the expanded graphite accounts for 60% of the total mass of EG and GO and is stirred uniformly.
(3) And transferring the mixed solution into a reaction kettle, and placing the reaction kettle in a vacuum drying oven for hydrothermal reaction for 17 hours at 180 ℃ to obtain the rGO/EG mixed hydrogel.
(4) And (3) putting the hydrogel into a freeze dryer for vacuum freeze-drying for 24 hours at the temperature of-50 ℃ to obtain the rGO/EG mixed aerogel.
(5) Cut the mixed aerogel of rGO/EG into the cake that thickness is 5mm, put into the paraffin that melts completely, the mixed aerogel of rGO/EG adsorbs paraffin rapidly, treats that paraffin adsorbs to saturation, takes out, and natural cooling obtains the mixed graphene aerogel phase transition composite material of no ion cross-linking, and the quality is 2.3102 g. In this embodiment, the scanning electron microscope image of the rGO/EG mixed aerogel in step (4) is shown in fig. 2a, and it can be seen that the structure of the mixed graphene aerogel is loose, and the mixed graphene aerogel is in a lamellar distribution.
The infrared spectrogram of the phase-change composite material is shown in FIG. 3, and the thermal conductivity of the phase-change composite material measured by a steady-state flat plate method is 0.40 W.m. shown in FIG. 4-1·K-1。
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.
Claims (10)
1. The utility model provides an ionic crosslinking's mixed graphite alkene aerogel phase transition combined material which characterized in that, phase transition combined material contains heat conduction filler material, phase transition material and cross-linking material, heat conduction filler material is mixed graphite alkene aerogel, mixed graphite alkene aerogel comprises oxidation graphite alkene and expanded graphite.
2. The ion-crosslinked hybrid graphene aerogel phase-change composite material as claimed in claim 1, wherein the mass fraction of expanded graphite in the hybrid graphene aerogel is 50-70%.
3. The ionically-crosslinked hybrid graphene aerogel phase change composite according to claim 1, wherein the phase change material is paraffin.
4. The ionically crosslinked hybrid graphene aerogel phase change composite according to claim 1, wherein the crosslinking material is a metal chloride salt.
5. The ionic crosslinked hybrid graphene aerogel phase change composite according to claim 4, wherein the metal chloride salt is selected from KCl, MgCl2Or FeCl3One or more of (a).
6. The ion-crosslinked hybrid graphene aerogel phase-change composite material as claimed in claim 1, wherein the addition ratio of the heat-conducting filling material, the phase-change material and the crosslinking material is 1g (10.5-13.7 g) to 0.02-0.4 mmol.
7. The preparation method of the graphene aerogel phase change composite material according to any one of claims 1 to 6, wherein the preparation method specifically comprises the following steps:
(a) mixing the graphene oxide solution with the expanded graphite, adding the crosslinking material solution, mixing, and performing hydrothermal reaction to obtain the ionic crosslinked hybrid graphene hydrogel;
(b) freeze-drying the ion-crosslinked hybrid graphene hydrogel obtained in the step (a) to obtain an ion-crosslinked hybrid graphene aerogel;
(c) and (c) putting the ion-crosslinked hybrid graphene aerogel obtained in the step (b) into a molten phase-change material, and naturally cooling after the phase-change material is adsorbed to saturation to obtain the ion-crosslinked hybrid graphene aerogel phase-change composite material.
8. The method for preparing an ion-crosslinked hybrid graphene aerogel phase-change composite material according to claim 7, wherein in the step (a), the graphene oxide solution is prepared by a modified Hummer method, and the concentration of graphene oxide in the graphene oxide solution is 10 mg/ml;
in the step (a), carrying out hydrothermal reaction in a reaction kettle, wherein the reaction kettle is arranged in a vacuum drying oven, the temperature of the vacuum drying oven is 160-200 ℃, and the reaction time is 15-19 h;
in the step (a), the concentration of the crosslinking material solution is 20-400 mM.
9. The preparation method of the ion-crosslinked hybrid graphene aerogel phase-change composite material according to claim 7, wherein in the step (b), the freeze-drying is performed under a vacuum condition, the freeze-drying temperature is-70-0 ℃, and the freeze-drying time is 22-26 h.
10. The method for preparing the ion-crosslinked hybrid graphene aerogel phase-change composite material according to claim 7, wherein in the step (c), the ion-crosslinked hybrid graphene aerogel is cut into a cake with a thickness of 2-8 cm, and then the cake is placed in the melted phase-change material.
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