Graphene high-temperature electrothermal film and preparation method thereof

Abstract

The application provides a graphene high-temperature electric heating film and a preparation method thereof, wherein the preparation method comprises the following steps: purifying and drying a graphene mixed solution containing a few-layer graphene with a sheet structure; weighing a certain amount of the purified graphene, dissolving the graphene in deionized water, and ultrasonic dispersion to prepare a graphene dispersion solution; adding mica powder into the graphene dispersion solution and then grinding to obtain a composite conductive slurry with a particle size of 20-50 mu m; coating the composite conductive slurry and drying to obtain a high-square-resistance graphene film, and then performing calendering and low-temperature annealing to form a low-square-resistance graphene film; and finally, adding an electrode to the low-square-resistance graphene film to prepare the graphene electric heating film. The graphene dispersion solution is mixed with the mica powder slurry, the mixture is grinded to prepare a slurry, coated to form a film, and then subjected to low-temperature annealing and electrode installation to prepare the high-temperature electric heating film. The high-temperature electric heating film has a heating temperature of 300 DEG C or above at a voltage of 5V-12V, and the temperature attenuation rate is less than 10% when working at the temperature for 5000h. In addition, the surface heating temperature is uniform, and the high-temperature cyclic heating stability is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of graphene high-temperature electric heating film, and particularly relates to a graphene high-temperature electric heating film and a preparation method thereof. BACKGROUND

[0002] At present, graphene high-temperature electric heating films (also referred to as graphene high-temperature electric heating films) appearing on the market are generally high-temperature electric heating films prepared by using high-temperature-resistant organic silicone resin as an adhesive, high-boiling-point organic solvent as a dispersing agent and graphene as a conductive filler. Since the organic solvent is left and the organic silicone resin itself is attenuated and decomposed at a high temperature higher than 250 DEG C, the high-temperature electric heating film has a short service life and is difficult to stably generate heat at a high temperature of 300 DEG C. In order to ensure that the graphene electric heating film stably generates heat at 300 DEG C and prolong the service life of the electric heating film, a high-temperature-resistant graphene carrier is very important. Based on the deficiencies in the prior art, the application is proposed. SUMMARY

[0003] Therefore, the technical problem to be solved by the application is to provide a graphene high-temperature electric heating film and a preparation method thereof to overcome the deficiencies of the graphene high-temperature electric heating film in the prior art, i.e., short service life and difficulty in stably generating heat at a high temperature of 300 DEG C.

[0004] In order to solve the above problems, the application provides a preparation method of a graphene high-temperature electric heating film, comprising the following steps:

[0005] S100, preparing a graphene mixed solution, wherein the graphene in the graphene mixed solution is a few-layer sheet structure;

[0006] S200, purifying and drying the graphene mixed solution to form pure graphene;

[0007] S300, weighing a first mass of the graphene, dissolving the graphene in deionized water and ultrasonically dispersing to configure a graphene dispersion liquid with a target concentration;

[0008] S400, adding a second mass of mica powder to the graphene dispersion liquid, so that the graphene is intercalated between the sheet layers of the mica powder, and then grinding to obtain a composite conductive slurry with a particle size of 20-50 mu m;

[0009] S500, coating the composite conductive slurry and drying to obtain a high-sheet-resistance graphene film with a first thickness;

[0010] S600, subjecting the high-sheet-resistance graphene film to calendering and low-temperature annealing treatment to form a low-sheet-resistance graphene film with a second thickness;

[0011] S700, installing an electrode to the low-sheet-resistance graphene film to manufacture a graphene electric heating film.

[0012] In some embodiments, the step S100 specifically comprises:

[0013] S110, intercalation expansion of the graphite paper under a constant current condition, taking the graphite paper as a positive electrode and 98wt% concentrated sulfuric acid as an electrolyte;

[0014] S120, complete exfoliation of the intercalation expanded graphite paper under a target temperature and a constant voltage condition, taking the intercalation expanded graphite paper as a positive electrode and a preset concentration of sulfuric acid as an electrolyte, to obtain the graphene mixed solution of the multi-layer sheet structure graphene.

[0015] In some embodiments,

[0016] The constant current condition in the step S110 is 0.1A-0.5A, 30min-1h;

[0017] In some embodiments,

[0018] The preset concentration in the step S120 is 20wt%-60wt%; and,

[0019] The target temperature in the step S120 is 50-80℃; the constant voltage condition is 5V-10V, 5h-8h.

[0020] In some embodiments, the step S200 of purifying and drying the graphene mixed solution to form pure graphene specifically comprises:

[0021] The graphene mixed solution is filtered, then washed with deionized water, and then naturally dried.

[0022] In some embodiments,

[0023] The ultrasonic condition in the step S300 is 350W-500W, 1h-3h.

[0024] In some embodiments,

[0025] In the step S400, the mica powder is 200 mesh-300 mesh, and the content of the mica powder in the composite conductive slurry is 5%-15%; and / or,

[0026] In the step S500, the drying temperature of the composite conductive slurry is 80℃-100℃.

[0027] In some embodiments,

[0028] The first thickness is 50-200μm; and the second thickness is 20-100μm.

[0029] In some embodiments,

[0030] The temperature of the low-temperature annealing treatment in the step S600 is 200-300 DEG C.

[0031] The application further provides a graphene high-temperature electrothermal film prepared by the preparation method of the graphene high-temperature electrothermal film.

[0032] The application provides a graphene high-temperature electrothermal film and a preparation method thereof. Mica powder is long-term stable at a high temperature of 300 DEG C due to its excellent high-temperature resistance, and can be used as an intercalation carrier due to its lamellar structure. When the mica powder is dissolved with a graphene dispersion liquid, the mica powder swells by absorbing water, and the intercalation effect is formed between the mica powder and the multilayer graphene in the graphene dispersion liquid. The intercalation effect is beneficial to the dispersion of the graphene in the high-temperature carrier, and further makes the graphene high-temperature electrothermal film generate heat more uniformly. In the technical scheme of the application, the graphene dispersion liquid with multilayer graphene is mixed with the mica powder slurry with the lamellar structure, grinded into a slurry, coated into a film, then subjected to low-temperature annealing, and finally prepared into the graphene high-temperature electrothermal film by loading electrodes. The graphene high-temperature electrothermal film generates heat at a temperature of 300 DEG C or above under a voltage of 5-12 V, and the temperature attenuation rate is less than 10% when working at the temperature for 5000 h. The surface heat generation temperature is uniform, and the graphene high-temperature electrothermal film has good high-temperature cycle heat generation stability. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The figure shows the preparation method of the graphene high-temperature electrothermal film according to an embodiment of the application. DETAILED DESCRIPTION

[0034] Referring to Figure 1 The figure shows the preparation method of the graphene high-temperature electrothermal film according to an embodiment of the application, which comprises the following steps:

[0035] S100, preparing a graphene mixed liquid, wherein the graphene in the graphene mixed liquid has a structure of several layers of lamellas;

[0036] S200, purifying and drying the graphene mixed liquid to form pure graphene;

[0037] S300, weighing a first mass of graphene, dissolving the graphene in deionized water, and ultrasonically dispersing the graphene to prepare a graphene dispersion liquid with a target concentration;

[0038] S400, adding a second mass of mica powder into the graphene dispersion liquid, wherein the mica powder swells by absorbing water, the gap between the lamellas of the mica powder increases, and the graphene is intercalated between the lamellas of the mica powder, and then the graphene is grinded to obtain a composite conductive slurry with a particle size of 20-50 mu m;

[0039] S500, coating the composite conductive slurry and drying to obtain a high-sheet-resistance graphene film with a first thickness;

[0040] S600, the high sheet resistance graphene film is subjected to calendering and low-temperature annealing to form a low sheet resistance graphene film with a second thickness;

[0041] S700, an electrode is added to the low sheet resistance graphene film to form a graphene electrothermal film.

[0042] In the technical scheme, the mica powder is long-term stable at 300 DEG C high temperature due to its excellent high-temperature resistance, and can be used as an intercalation carrier due to its lamellar structure. When the mica powder is dissolved in the graphene dispersion liquid, the mica powder swells by absorbing water and forms an intercalation effect with the multi-layer lamellar graphene in the graphene dispersion liquid. The intercalation effect is beneficial to the dispersion of the graphene in the high-temperature carrier (i.e. the mica powder), and thus the heating of the high-temperature electrothermal film is more uniform. In the technical scheme, the graphene dispersion liquid with multi-layer lamellar graphene is mixed with the mica powder slurry with lamellar structure, grinded into slurry, coated into a film, and then subjected to low-temperature annealing and electrode addition to prepare a high-temperature electrothermal film. The high-temperature electrothermal film has a heating temperature of 300 DEG C or above at 5V-12V voltage, and has a temperature attenuation rate of less than 10% after working at the temperature for 5000h, and the surface heating temperature is uniform, showing good high-temperature cycle heating stability.

[0043] In some embodiments, step S100 specifically comprises:

[0044] S110, intercalation expansion of the graphite paper is performed under a constant current condition by taking the graphite paper as a positive electrode and 98wt% concentrated sulfuric acid as an electrolyte.

[0045] S120, complete exfoliation of the graphite paper is performed under a target temperature and a constant voltage condition by taking the intercalation expanded graphite paper as a positive electrode and sulfuric acid with a preset concentration as an electrolyte, to obtain a graphene mixed liquid with a multi-layer lamellar structure.

[0046] In a specific embodiment, the constant current condition in step S110 is 0.1A-0.5A for 30min-1h, the preset concentration in step S120 is 20wt%-60wt%, and the target temperature in step S120 is 50-80 DEG C, and the constant voltage condition is 5V-10V for 5h-8h.

[0047] Since the traditional chemical oxidation exfoliation method has a high oxidation degree of graphene oxide, a high-temperature heat treatment at 3000 DEG C is required to prepare self-annealed graphene, and the preparation process is relatively complex and has a high cost. In the technical scheme, the electrochemical exfoliation method is used to prepare graphene with a multi-layer lamellar structure, and the process is simple and has a low preparation cost.

[0048] In some embodiments, the purifying and drying of the graphene mixture in step S200 specifically comprises: filtering the graphene mixture, then washing with deionized water, and then naturally drying, so as to ensure the purity of the graphene.

[0049] In step S300, the ultrasonic conditions are 350W-500W, 1h-3h, so as to ensure that the graphene in the graphene dispersion is fully dissolved and uniformly distributed.

[0050] In step S400, the mica powder is 200-300 mesh, and the content of the mica powder in the composite conductive paste is 5%-15%, so as to ensure that the graphene electrothermal film prepared has a low attenuation rate, a low square resistance, and good high-temperature resistance.

[0051] In step S500, the drying temperature of the composite conductive paste is 80-100℃. Below this temperature, the drying speed is very slow, resulting in low preparation efficiency, and above this temperature, the intercalation structure of graphene and mica powder in the composite conductive paste is easily destroyed, which reduces the toughness of the film after film formation.

[0052] The first thickness is 50-200μm, and the second thickness is 20-100μm. When the thickness is higher than the above range, the film is too thin, and the mechanical strength of the film is very low, which does not meet the preparation requirements of the graphene high-temperature electrothermal film. If it is too thick, it will increase the film formation time, and will reduce the heating stability and flexibility of the electrothermal film.

[0053] In step S600, the temperature of the low-temperature annealing treatment is 200-300℃. Below 200℃, the purpose of annealing cannot be achieved. After annealing treatment, the graphene has impurity atoms precipitated and lattice rearranged, and the conductivity is greatly improved, so the square resistance of the electrothermal film after low-temperature annealing treatment decreases rapidly. In order to achieve the purpose of energy saving and cost reduction, the temperature is not higher than 300℃.

[0054] The preparation method of the graphene high-temperature electrothermal film of the present application is further described in combination with several examples and comparative examples.

[0055] Example 1

[0056] A preparation method of a graphene high-temperature electrothermal film, specifically comprising:

[0057] 1) using a graphite paper as a positive electrode and 98wt% concentrated sulfuric acid as an electrolyte, intercalating and expanding the graphite paper for 1h under a constant current of 0.1A to obtain an intercalated and expanded graphite paper;

[0058] 2) The intercalated and expanded graphite paper is used as a positive electrode, 60wt% sulfuric acid is used as electrolyte, the graphite paper is completely exfoliated at 80℃ and 5V constant voltage for 6h, and a mixed solution of several layers of graphene is obtained;

[0059] 3) The mixed solution of graphene is filtered, impurities are removed by deionized water washing, and the pure graphene is obtained by natural drying;

[0060] 4) A certain mass of graphene is weighed, deionized water is used as a solvent, and a graphene dispersion solution with a certain concentration is prepared by ultrasonic dispersion at 350W for 2h;

[0061] 5) A certain amount of 200-mesh mica powder is added to the prepared graphene dispersion solution, the mica powder is swelled by water, the interlayer space of the mica powder is increased, and then the graphene is intercalated between the layers of the mica powder, and then the composite conductive paste with a particle size of 20-50μm is obtained by grinding (the content of mica powder is 2%);

[0062] 6) The composite conductive paste is coated on the glass fiber cloth by means of scraping, and then the graphene film with a thickness of 70μm and a high square resistance of 4376Ω / sq is obtained by drying in an oven at 80℃ for 30min;

[0063] 7) The graphene film with high square resistance is calendered and annealed at 300℃, and then the graphene film with a thickness of 50μm and a low square resistance of 1.2Ω / sq is obtained;

[0064] 8) The electrode is installed on the graphene film with low square resistance, and the graphene high-temperature electrothermal film is prepared.

[0065] The electrothermal film is applied with a voltage of 5V, and the steady-state temperature reaches 386℃. After working for 5000h, the temperature attenuation rate is 19.3%.

[0066] Example 2

[0067] A preparation method of a graphene high-temperature electrothermal film, specifically comprising:

[0068] 1) The graphite paper is used as a positive electrode, 98wt% concentrated sulfuric acid is used as electrolyte, and the graphite paper is intercalated and expanded at a constant current of 0.3A for 1h, and then the intercalated and expanded graphite paper is obtained;

[0069] 2) The intercalated and expanded graphite paper is used as a positive electrode, 40wt% sulfuric acid is used as electrolyte, the graphite paper is completely exfoliated at 80℃ and 8V constant voltage for 6h, and a mixed solution of several layers of graphene is obtained;

[0070] 3) The mixed solution of graphene is filtered, impurities are removed by deionized water washing, and the pure graphene is obtained by natural drying;

[0071] 4) Take a certain mass of graphene, use deionized water as solvent, ultrasonic dispersion for 1h at 500W, and prepare a certain concentration of graphene dispersion liquid;

[0072] 5) Add a certain amount of 200 mesh mica powder to the prepared graphene dispersion liquid, and the mica powder swells and the interlayer space increases at the same time, so that the graphene is intercalated between the layers of the mica powder, and then the composite conductive paste with a particle size of 20-50μm is obtained by grinding (the content of mica powder is 5%);

[0073] 6) The composite conductive paste is coated on the glass fiber cloth by scraping, and then dried in a 60℃ oven for 1h to obtain a graphene film with a thickness of 50μm and a high square resistance of 5384Ω / sq;

[0074] 7) The high square resistance graphene film is calendered and annealed at 250℃, and finally a low square resistance graphene film with a thickness of 30μm and a square resistance of 1.7Ω / sq is obtained;

[0075] 8) An electrode is added to the low square resistance graphene film to make a graphene high-temperature electrothermal film.

[0076] The electrothermal film applies a voltage of 5V, and the steady-state temperature reaches 363℃. After working for 5000h, the temperature attenuation rate is 9.6%.

[0077] Example 3

[0078] A preparation method of a graphene high-temperature electrothermal film, specifically comprising:

[0079] 1) Take a graphite paper as a positive electrode, and use 98wt% concentrated sulfuric acid as an electrolyte to make the graphite paper intercalate and swell for 1h under a constant current of 0.5A, so as to obtain an intercalated and swollen graphite paper;

[0080] 2) Take the intercalated and swollen graphite paper as a positive electrode, and use 60wt% sulfuric acid as an electrolyte to make the graphite paper completely exfoliate under a constant voltage of 60℃ and 10V for 6h, so as to obtain a graphene mixed solution with several layers of sheets;

[0081] 3) Filter the graphene mixed solution, wash with deionized water to remove impurities, and naturally dry to obtain pure graphene;

[0082] 4) Take a certain mass of graphene, use deionized water as solvent, ultrasonic dispersion for 2h at 500W, and prepare a certain concentration of graphene dispersion liquid;

[0083] 5) add a certain amount of 250-mesh mica powder to the prepared graphene dispersion liquid, the mica powder swells by absorbing water, and the interlayer space increases, so that the graphene is intercalated between the layers of the mica powder, and then grinding obtains a composite conductive paste with a particle size of 20-50 μm (the content of mica powder is 10%);

[0084] 6) the composite conductive paste is coated on the glass fiber cloth by means of scraping, and is placed in a 60℃ oven for drying for 1 h, to obtain a graphene film with a thickness of 70 μm and a high square resistance of 5672 Ω / sq;

[0085] 7) the graphene film with high square resistance is calendered and annealed at 300℃, and finally a graphene film with a thickness of 50 μm and a low square resistance of 2.6 Ω / sq is obtained;

[0086] 8) an electrode is added to the graphene film with low square resistance to prepare a graphene high-temperature electrothermal film.

[0087] The electrothermal film applies a voltage of 5V, and the steady-state temperature reaches 336℃, and after working for 5000 h, the temperature attenuation rate is 6.7%.

[0088] Example 4

[0089] A preparation method of a graphene high-temperature electrothermal film, specifically comprising:

[0090] 1) using a graphite paper as a positive electrode and 98wt% concentrated sulfuric acid as an electrolyte, the graphite paper is intercalated and swelled for 1 h under a constant current of 0.3 A to obtain an intercalated and swelled graphite paper;

[0091] 2) using the intercalated and swelled graphite paper as a positive electrode and 40wt% sulfuric acid as an electrolyte, the graphite paper is completely exfoliated under a constant voltage of 8V and at 80℃ for 6 h to obtain a graphene mixed liquid with several layers;

[0092] 3) filtering the graphene mixed liquid, washing with deionized water to remove impurities, and naturally drying to obtain pure graphene;

[0093] 4) weighing a certain amount of graphene, using deionized water as a solvent, ultrasonic dispersion at 350W for 2 h to prepare a graphene dispersion liquid with a certain concentration;

[0094] 5) adding a certain amount of 300-mesh mica powder to the prepared graphene dispersion liquid, the mica powder swells by absorbing water, and the interlayer space increases, so that the graphene is intercalated between the layers of the mica powder, and then grinding obtains a composite conductive paste with a particle size of 20-50 μm (the content of mica powder is 15%);

[0095] 6) The composite conductive paste is coated on the glass fiber cloth by means of scraping, and is placed in a 60℃ oven for drying for 1h to obtain a graphene film with a thickness of 50μm and a high square resistance of 3798Ω / sq;

[0096] 7) The graphene film with high square resistance is subjected to calendering and 200℃ annealing treatment, and finally a graphene film with a thickness of 30μm and a low square resistance of 3.4Ω / sq is obtained;

[0097] 8) An electrode is installed on the graphene film with low square resistance to prepare a graphene high-temperature electrothermal film.

[0098] The electrothermal film is applied with a voltage of 5V, and the steady-state temperature reaches 297℃. After working for 5000h, the temperature attenuation rate is 8.3%.

[0099] Example 5

[0100] A preparation method of a graphene high-temperature electrothermal film, specifically comprising:

[0101] 1) Graphite paper is used as a positive electrode, and 98wt% concentrated sulfuric acid is used as an electrolyte. The graphite paper is intercalated and expanded for 1h under a constant current of 0.1A to obtain an intercalated and expanded graphite paper;

[0102] 2) The intercalated and expanded graphite paper is used as a positive electrode, and 40wt% sulfuric acid is used as an electrolyte. The graphite paper is completely exfoliated for 6h under a constant voltage of 80℃ and 10V to obtain a graphene mixed solution with several layers of sheet;

[0103] 3) The graphene mixed solution is filtered, impurities are removed by washing with deionized water, and the graphene is naturally dried to obtain pure graphene;

[0104] 4) A certain mass of graphene is weighed, deionized water is used as a solvent, and a graphene dispersion solution with a certain concentration is prepared by ultrasonic dispersion at 500W for 2h;

[0105] 5) A certain amount of 200-mesh mica powder is added to the prepared graphene dispersion solution. The mica powder is swelled by water, and the interlayer space of the mica powder is increased, so that the graphene is intercalated between the layers of the mica powder. Then, the composite conductive paste with a particle size of 20-50μm (the content of mica powder is 20%) is obtained by grinding;

[0106] 6) The composite conductive paste is coated on the glass fiber cloth by means of scraping, and is placed in a 60℃ oven for drying for 1h to obtain a graphene film with a thickness of 70μm and a high square resistance of 6751Ω / sq;

[0107] 7) The graphene film with high square resistance is subjected to calendering and 200℃ annealing treatment, and finally a graphene film with a thickness of 50μm and a low square resistance of 6.7Ω / sq is obtained;

[0108] 8) In the low sheet resistance of graphene film on the electrode, made of graphene high temperature electric heating film.

[0109] The electric heating film applied 5V voltage, steady state temperature of 217℃, after 5000h work, temperature attenuation rate of 4.5%.

[0110] Comparative Example 1

[0111] A kind of graphene high temperature electric heating film preparation method, specifically:

[0112] 1) the graphite paper as anode, 98wt% concentrated sulfuric acid as electrolyte, under 0.1A constant current, make graphite paper intercalation expansion 1h, obtain intercalated graphite paper after expansion;

[0113] 2) the intercalated graphite paper after expansion as anode, 40wt% sulfuric acid as electrolyte, at 80℃ and 10V constant voltage work 6h make graphite paper completely exfoliate, obtain several layers of sheet-shaped graphene mixed solution;

[0114] 3) the graphene mixed solution is filtered, impurities are removed by deionized water washing, and is naturally dried, to obtain pure graphene;

[0115] 4) a certain mass of graphene is weighed, deionized water is used as solvent, ultrasonic dispersion is carried out at 500W for 2h, and a certain concentration of graphene dispersion liquid is configured;

[0116] 5) the graphene dispersion liquid is formed into graphene film with uniform thickness on the filter membrane by suction filtration method;Put into 60℃ oven, dry 1h, obtain graphene film with thickness of 70 μm and sheet resistance of 1796 Ω / sq high sheet resistance;

[0117] 6) the graphene film with high sheet resistance is calendered and annealed at 300℃, finally obtain graphene film with thickness of 50 μm and sheet resistance of 0.8 Ω / sq low sheet resistance;

[0118] 7) In the low sheet resistance of graphene film on the electrode, made of graphene high temperature electric heating film. The electric heating film applied 5V voltage, steady state temperature of 432℃, after 5000h work, temperature attenuation rate of 20%.

[0119] The related process conditions and parameter indexes of the above examples and comparative examples are shown in the following table:

[0120]

[0121]

[0122] The application utilizes the high temperature resistance and the sheet structure of the inorganic material mica powder, and the mica powder becomes the intercalation carrier of graphene, and the graphene electrothermal film with high temperature resistance is prepared, and when the content of the mica powder is 5-15%, the sheet resistance of the graphene electrothermal film after annealing treatment is lower than 1.7-3.4Ω·sq -1 When a voltage of 5V is applied to the electrothermal film, the heating temperature is above 300℃, and the temperature attenuation rate is below 10% after working for 5000h, compared with the pure graphene electrothermal film (comparative example 1), the graphene electrothermal film with high temperature resistance prepared by the application has good high temperature resistance. In example 1, the attenuation rate of the electrothermal film is high (19.3%) due to the low content of the mica powder (2%), and the high temperature resistance is poor, but if the content of the mica powder is too high (20%, example 5), the sheet resistance of the electrothermal film is large, and when the voltage is low (5V), the temperature can only reach 217℃, and the voltage needs to be increased to increase the temperature of the electrothermal film.

[0123] According to the embodiment of the application, a graphene high temperature electrothermal film is also provided, which is prepared by the above preparation method.

[0124] It is easy for those skilled in the art to understand that the above advantageous modes can be freely combined and superimposed without conflict.

[0125] The above is only the preferred embodiment of the application, and is not used to limit the application, and any modification, equivalent replacement and improvement within the spirit and principle of the application should be included in the protection scope of the application. The above is only the preferred embodiment of the application, and it should be pointed out that, for ordinary skilled in the art, without departing from the technical principle of the application, a number of improvements and modifications can be made, and these improvements and modifications should be regarded as the protection scope of the application.

Claims

1. A method for preparing a graphene high-temperature electrothermal film, characterized in that, The preparation method comprises the following steps: S100, preparing a graphene mixed solution, wherein the graphene in the graphene mixed solution is a few-layer sheet structure; S200, purifying and drying the graphene mixed solution to form pure graphene; S300, weighing a first mass of the graphene, dissolving the graphene in deionized water, and ultrasonic dispersion to configure a graphene dispersion liquid with a target concentration; S400, adding a second mass of mica powder into the graphene dispersion liquid to make the graphene intercalate between the sheet layers of the mica powder, and then grinding to obtain a composite conductive slurry with a particle size of 20-50 μm, the mica powder is 200-300 mesh, and the content of the mica powder in the composite conductive slurry is 5-15%; S500, coating the composite conductive slurry and drying to obtain a high sheet resistance graphene film with a first thickness, and the drying temperature of the composite conductive slurry is 80-100℃; S600, calendering and low-temperature annealing the high sheet resistance graphene film to form a low sheet resistance graphene film with a second thickness, and the low sheet resistance graphene film has a sheet resistance of 1.7 Ω·sq -1 - 3.4 Ω·sq -1 , and the low-temperature annealing has a temperature of 200-300℃. S700, installing an electrode to the low sheet resistance graphene film to form a graphene electrothermal film.

2. The production method according to claim 1, characterized by, The step S100 specifically comprises: S110, intercalating and expanding the graphite paper under a constant current condition by taking the graphite paper as a positive electrode and 98 wt% concentrated sulfuric acid as an electrolyte; S120, completely exfoliating the graphite paper under a target temperature and a constant voltage condition by taking the intercalated and expanded graphite paper as a positive electrode and a preset concentration of sulfuric acid as an electrolyte, to obtain the graphene mixed solution containing the graphene with the few-layer sheet structure.

3. The preparation method according to claim 2, wherein the constant current condition in the step S110 is 0.1-0.5 A for 30-60 min.

4. The preparation method according to claim 2, wherein the preset concentration in the step S120 is 20-60 wt%, and the target temperature in the step S120 is 50-80℃, and the constant voltage condition is 5-10 V for 5-8 h. The step S200 of purifying and drying the graphene mixed solution to form pure graphene specifically comprises: filtering the graphene mixed solution, then washing with deionized water, and then naturally drying.

6. The preparation method according to claim 1, wherein the ultrasonic condition in the step S300 is 350-500 W for 1-3 h.

5. The preparation method according to claim 1, characterized in that, 7. The preparation method according to claim 1, wherein the first thickness is 50-200 μm, and the second thickness is 20-100 μm. The graphene high-temperature electrothermal film is prepared by the preparation method of any one of claims 1-7. ​ ​ ​ ​ 8. A graphene high temperature electrocaloric film, characterized by, ​

Images