An ultrathin light-soft biomass heat-conducting film material and a preparation method thereof

Abstract

The present application belongs to the technical field of biomass heat-conducting film material preparation, and particularly relates to an ultrathin light and soft biomass heat-conducting film material and a preparation method thereof. First, a spinning solution is prepared from biomass raw materials and graphene oxide, the biomass raw materials including lignin cellulose, chitin, sodium alginate, regenerated plant protein and the like, and then an ultrathin light and soft biomass heat-conducting film material is finally prepared through electrostatic spinning technology and gradient calcination treatment. The present application uses biomass as raw material, is widely sourced, is environmentally friendly, and can heat-reduce graphene oxide to graphene while carbonizing the biomass material through gradient calcination. The heat-conducting film material prepared in this way has the advantages of ultrathin lightness, high heat conduction efficiency, low cost, easy preparation and the like.

Description

Technical Field

[0001] This invention belongs to the field of biomass thermal conductive film material preparation technology, specifically relating to an ultrathin and flexible biomass thermal conductive film material and its preparation method. Background Technology

[0002] In recent years, with the continuous improvement of the integration, operating frequency, and power density of electronic devices, the overheating problem of electronic devices has become increasingly serious. The main strategy to solve the overheating problem is to conduct excess energy from electronic devices to the external environment through thermal management materials. The preparation of thermal conductive films is not only related to performance indicators such as thermal conductivity, uniformity, reliability, durability, and low cost, but also, in practical applications, thin, lightweight, and flexible thermal conductive film materials are more popular. These parameters are closely related to the actual production process. Conventional flexible thermal conductive film materials are mainly divided into four types: pure polymer films, all-carbon films, carbon-based / polymer films, and ceramic / polymer films. Flexible thermal conductive film materials are suitable for thermal management scenarios that require high in-plane heat conduction and excellent flexibility, such as flexible film heat sinks, human body thermal management, energy storage devices, and electrothermal cooling devices.

[0003] Flexible thermally conductive thin film materials possess ultra-high in-plane thermal conductivity and excellent flexibility. When used as film heat sinks, they can uniformly conduct heat from a point heat source to a large surface area, and then dissipate heat through large-area convection and radiation. They are currently widely used in smartphones and are expected to be applied in ultra-thin laptops, flexible wearable devices, and smart home appliances in the future. However, traditional thermally conductive film materials are mostly made from synthetic plastics, rubber, and other polymer composite materials, which cannot be naturally degraded. Given the limited lifespan of smartphones and other electronic devices, this places enormous pressure on environmental protection. Therefore, the preparation of thermally conductive thin films using biodegradable materials has become a research hotspot.

[0004] In Chinese patent CN202110169207.1, a biodegradable biomass-based composite thermal conductive material and its preparation method are disclosed, a biodegradable thermal conductive film is prepared by ball milling and hot pressing of biomass polymer materials and thermal conductive fillers. However, its thermal conductivity still needs to be improved, and its elongation at break is low, which limits its application. Summary of the Invention

[0005] This invention proposes an ultrathin and flexible biomass thermal conductive film material and its preparation method. The biomass thermal conductive film is prepared by blending biomass and graphene oxide to prepare a spinning solution. Then, the biomass material is carbonized by gradient calcination, while the graphene oxide is thermally reduced to graphene. The thermal conductive film prepared by this method has the advantages of being ultrathin and flexible, low cost, and easy to prepare.

[0006] The present invention adopts the following technical solution:

[0007] A method for preparing an ultrathin, lightweight, and flexible biomass thermal conductive film material involves preparing a spinning solution from biomass raw materials and graphene oxide, forming a film using an electrospinning process, and calcining the spun film using a gradient carbonization process to obtain the ultrathin, lightweight, and flexible thermal conductive film material. The specific steps are as follows:

[0008] (1) Mix graphene oxide and DMF, disperse in ultrasonic waves for 4-6 hours, then add biomass raw materials and solvent and mix evenly to obtain spinning solution;

[0009] The biomass raw materials include lignin cellulose, chitin, sodium alginate, and regenerated plant protein, with a molar ratio of 1:1:1 to 2:0 to 2. These materials each have different mechanical properties, such as strength and flexibility. Using them in appropriate proportions can optimize the mechanical properties of the final product.

[0010] The amount of graphene oxide added is 1.6%-3.0% of the total mass of the biomass raw material;

[0011] The solvent is one or a mixture of water, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), and 2,2,5,5-tetramethyltetrahydrofuran-3-one (TMF);

[0012] The mixing conditions are magnetic heating and stirring, with a stirring temperature of 30-100℃ and a stirring time of 60-720 min;

[0013] (2) The mixed spinning solution is electrospun into a film using a spinning device. The spinning conditions are: electric field strength of 8-20kV, rotation speed of 300-800r / min, collection distance of 5-10cm, pore size of 0.6μm, and spinning speed of 0.5mL / h.

[0014] (3) The fiber membrane obtained by spinning is calcined. The calcination gradient is divided into a pre-oxidation temperature range and a carbonization temperature range. The pre-oxidation temperature range is 220-300℃, the heating rate is 0.5-5℃ / min, and the time is 40min. The carbonization temperature range is 300-800℃, the heating rate is 0.5-20℃ / min, and the time is 30min. After calcination, it is slowly cooled (cooling rate is 2℃ / min) to obtain an ultra-thin and flexible biomass thermal conductive film material.

[0015] Gradient carbonization has the following advantages: (1) It can precisely control the structural changes inside the fiber, thereby optimizing the formation of heat conduction channels; (2) By gradually increasing the temperature, thermal stress can be reduced, and damage caused by rapid temperature changes can be avoided, thereby improving the overall performance of the material; (3) It helps to achieve uniformity in the carbonization process, avoid local overheating or insufficient carbonization, and thus obtain more uniform thermal conductivity.

[0016] Beneficial effects:

[0017] This invention utilizes electrospinning and gradient calcination of biomass raw materials and graphene oxide to ultimately produce an ultrathin, flexible biomass thermal conductive film material. By optimizing the composition of the biomass raw materials, gradient calcination of the carbonized biomass materials, and reduction of graphene oxide, the film structure is optimized, thereby achieving higher and more uniform thermal conductivity and tensile properties. The thermal conductive film prepared in this way has advantages such as being ultrathin, flexible, low-cost, easy to prepare, and environmentally friendly. It can easily adhere to irregular surfaces while maintaining the thin and light characteristics of the device. Attached Figure Description

[0018] Figure 1 These are electron microscope images of the ultrathin and flexible biomass thermal conductive film material in Example 1 before (ab) and after (cd) calcination;

[0019] Figure 2 The infrared image is of the ultrathin and flexible biomass thermal conductive film material in Example 1;

[0020] Figure 3 A comparison diagram of the thermal conductivity of the thermally conductive film materials prepared in the examples and the comparative examples;

[0021] Figure 4 A comparison diagram of the tensile strength of the thermally conductive film materials prepared in the examples and the control examples;

[0022] Figure 5 This is a comparison chart of the elongation at break of the thermally conductive film materials prepared in the examples and the control examples.

[0023] Figure 6 This is a comparison diagram of the water contact angles of the thermally conductive film materials prepared in the examples and the control examples. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] First, 0.20 g of graphene oxide was weighed and placed in a beaker, along with 10 mL of DMF solvent. The mixture was ultrasonically dispersed for 6 hours. Then, 3.42 g of lignin cellulose, 1.61 g of chitin, 2.16 g of sodium alginate, 1.28 g of regenerated plant protein, 10 mL of DMAC, and 10 mL of TMF solution were added. A magnetic stir bar was then added, and the mixture was stirred at 50°C for 5 hours. The mixed spinning solution was then passed through a spinning device and electrospun under the following conditions: an electric field strength of 10 kV, a rotation speed of 500 r / min, a collection distance of 6 cm, a pore size of 0.6 μm, and a spinning speed of 0.5 mL / h, to obtain the desired fiber morphology.

[0027] The spun fibers were calcined at a pre-oxidation temperature (260℃) with a heating rate controlled at 2℃ / min for 40 min to remove organic solvents and improve fiber structure. After pre-oxidation, calcination continued at a carbonization temperature (800℃) with a faster heating rate (8℃ / min) for 30 min to further carbonize the fibers and form heat-conducting channels. After calcination, the fibers were slowly cooled (at a cooling rate of 2℃ / min) to avoid structural damage due to rapid temperature changes, resulting in an ultrathin, flexible biomass thermal conductive film material with a thickness of 4.5 μm.

[0028] To verify the thermal conductivity of this ultrathin and flexible biomass thermal conductive film material, the thermal conductivity of the material was measured using a laser thermal conductivity meter (LFA467 / LFA467). The measurement was performed in parallel three times, and the thermal conductivity of the material was found to be 15.23 W / (m·K).

[0029] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.23 MPa and the elongation at break was 429%.

[0030] To verify the hydrophobic properties of this ultra-thin and flexible biomass thermal conductive film material, the water contact angle of the material was tested using a JC2000D1 contact angle measuring instrument, and the water contact angle of the material was measured to be 78°.

[0031] Example 2

[0032] The difference between Example 2 and Example 1 is that the amount of graphene oxide added is different, changed from 0.20g to 0.16g, otherwise the same as Example 1.

[0033] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 12.33 W / (m·K).

[0034] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.09 MPa and the elongation at break was 398%.

[0035] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 62°.

[0036] Example 3

[0037] The difference between Example 3 and Example 1 is that the amount of graphene oxide added is different, changing "adding 0.20g of graphene oxide" to "adding 0.25g of graphene oxide", and the rest is the same as Example 1.

[0038] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 14.22 W / (m·K).

[0039] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 3.29 MPa and the elongation at break was 423%.

[0040] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 77°.

[0041] Example 4

[0042] The difference between Example 4 and Example 1 is that the addition of "3.42g lignin cellulose, 1.61g chitosan cellulose, 2.16g sodium alginate, and 1.28g regenerated plant protein" is changed to the addition of "3.42g lignin cellulose, 1.61g chitosan, and 2.16g sodium alginate". The rest is the same as in Example 1.

[0043] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 14.10 W / (m·K).

[0044] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.11 MPa and the elongation at break was 409%.

[0045] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 68°.

[0046] Example 5

[0047] The difference between Example 5 and Example 1 is that "adding 2.16g sodium alginate and 1.28g regenerated plant protein" is changed to "adding 4.32g sodium alginate and 2.56g regenerated plant protein", while the rest is the same as Example 1.

[0048] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 12.20 W / (m·K).

[0049] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.16 MPa and the elongation at break was 421%.

[0050] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 71°.

[0051] Example 6

[0052] The difference between Example 6 and Example 1 is that "adding 10 mL of DMAC and 10 mL of TMF solution" is changed to "adding 5 mL of DMAC and 15 mL of TMF solution", otherwise it is the same as Example 1.

[0053] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 13.25 W / (m·K).

[0054] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.19 MPa and the elongation at break was 428%.

[0055] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 69°.

[0056] Example 7

[0057] The difference between Example 7 and Example 1 is that "adding 10 mL of DMAC and 10 mL of TMF solution" is changed to "adding 20 mL of DMF solution", otherwise it is the same as Example 1.

[0058] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 12.18 W / (m·K).

[0059] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.14 MPa and the elongation at break was 402%.

[0060] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 73°.

[0061] Example 8

[0062] The difference between Example 8 and Example 1 is that "ultrasonic dispersion in ultrasound for 6 hours" is changed to "ultrasonic dispersion in ultrasound for 4 hours", otherwise it is the same as Example 1.

[0063] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 13.03 W / (m·K).

[0064] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 3.89 MPa and the elongation at break was 392%.

[0065] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 70°.

[0066] Example 9

[0067] The difference between Example 9 and Example 1 is that "electric field strength is 10kV" is changed to "electric field strength is 8kV", otherwise it is the same as Example 1.

[0068] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 12.19 W / (m·K).

[0069] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.17 MPa and the elongation at break was 407%.

[0070] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 65°.

[0071] Example 10

[0072] The difference between Example 10 and Example 1 is that "electric field strength is 10kV" is changed to "electric field strength is 15kV", otherwise it is the same as Example 1.

[0073] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 11.21 W / (m·K).

[0074] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.11 MPa and the elongation at break was 412%.

[0075] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 60°.

[0076] Example 11

[0077] The difference between Example 11 and Example 9 is that "rotation speed of 500 r / min" is changed to "rotation speed of 300 r / min", otherwise it is the same as Example 9.

[0078] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 12.09 W / (m·K).

[0079] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.18 MPa and the elongation at break was 415%.

[0080] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 74°.

[0081] Example 12

[0082] The difference between Example 12 and Example 9 is that "rotation speed of 500 r / min" is changed to "rotation speed of 800 r / min", otherwise it is the same as Example 9.

[0083] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 13.01 W / (m·K).

[0084] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 3.88 MPa and the elongation at break was 386%.

[0085] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 64°.

[0086] Example 13

[0087] The difference between Example 13 and Example 9 is that "collection distance is 5cm" is changed from "collection distance is 6cm". Otherwise, they are the same as Example 9.

[0088] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 12.04 W / (m·K).

[0089] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 3.93 MPa and the elongation at break was 403%.

[0090] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 76°.

[0091] Example 14

[0092] The difference between Example 14 and Example 9 is that "collection distance is 6cm" is changed to "collection distance is 8cm", otherwise it is the same as Example 9.

[0093] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 11.14 W / (m·K).

[0094] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.12 MPa and the elongation at break was 417%.

[0095] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 70°.

[0096] Compare with Example 1

[0097] First, weigh 0.20 g of graphene oxide and place it in a beaker, add 10 mL of DMF solvent, and ultrasonically disperse it for 6 h. Then, add 5.14 g of lignin cellulose, 2.42 g of chitin, 10 mL of DMAC, and 10 mL of TMF solution. Subsequently, add a magnetic stir bar and stir at 50 °C for 5 h. Pass the mixed spinning solution through a spinning device and electrospin it under the conditions of an electric field strength of 10 kV, a rotation speed of 500 r / min, and a collection distance of 6 cm to obtain the ideal fiber morphology.

[0098] The spun fibers were calcined at a pre-oxidation temperature (260℃) with a heating rate controlled at 2℃ / min for 40 min to remove organic solvents and improve fiber structure. After pre-oxidation, calcination continued at a carbonization temperature (800℃) with a faster heating rate (8℃ / min) for 30 min to further carbonize the fibers and form heat-conducting channels. After calcination, the fibers were slowly cooled (at a cooling rate of 2℃ / min) to avoid structural damage due to rapid temperature changes.

[0099] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 5.98 W / (m·K).

[0100] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 3.65 MPa and the elongation at break was 327%.

[0101] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 58°.

[0102] Compare with Example 2

[0103] First, weigh out 3.42g of lignin cellulose, 1.61g of chitin, 2.16g of sodium alginate, 1.28g of regenerated plant protein, 10mL of DMAC, and 10mL of LTMF solution. Then, add a magnetic stir bar and stir at 50℃ for 5h. Pass the mixed spinning solution through a spinning device and perform electrospinning under the following conditions: electric field strength of 10kV, rotation speed of 500r / min, collection distance of 6cm, pore size of 0.6μm, and spinning speed of 0.5mL / h, to obtain the desired fiber morphology.

[0104] The spun fibers were calcined at a pre-oxidation temperature (260℃) with a heating rate controlled at 2℃ / min for 40 min to remove organic solvents and improve fiber structure. After pre-oxidation, calcination continued at a carbonization temperature (800℃) with a faster heating rate (8℃ / min) for 30 min to further carbonize the fibers and form heat-conducting channels. After calcination, the fibers were slowly cooled (at a cooling rate of 2℃ / min) to avoid structural damage due to rapid temperature changes.

[0105] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 1.13 W / (m·K).

[0106] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 3.21 MPa and the elongation at break was 332%.

[0107] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 55°.

[0108] Compare with Example 3

[0109] First, 0.20 g of graphene oxide was weighed and placed in a beaker, along with 10 mL of DMF solvent. The mixture was ultrasonically dispersed for 6 hours. Then, 3.42 g of lignin cellulose, 1.61 g of chitin, 2.16 g of sodium alginate, 1.28 g of regenerated plant protein, 10 mL of DMAC, and 10 mL of TMF solution were added. A magnetic stir bar was then added, and the mixture was stirred at 50°C for 5 hours. The mixed spinning solution was then passed through a spinning device and electrospun under the following conditions: an electric field strength of 10 kV, a rotation speed of 500 r / min, a collection distance of 6 cm, a pore size of 0.6 μm, and a spinning speed of 0.5 mL / h, to obtain the desired fiber morphology.

[0110] The spun fibers were calcined once at a temperature of 800℃, with the heating rate controlled at 5℃ / min. An appropriate holding time (45min) was maintained throughout the temperature range to ensure sufficient evaporation of the organic solvent, improve the fiber structure, and create heat-conducting channels. After calcination, the fibers were slowly cooled (at a cooling rate of 2℃ / min) to avoid structural damage due to rapid temperature changes.

[0111] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 10.15 W / (m·K).

[0112] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 4.05 MPa, and an elongation at break of 415%.

[0113] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 58°.

[0114] Compare with Example 4

[0115] First, 0.20 g of graphene oxide was weighed and placed in a beaker, along with 10 mL of DMF solvent. The mixture was then ultrasonically dispersed for 6 hours. Next, 3.42 g of lignin cellulose, 1.61 g of chitosan, 2.16 g of sodium alginate, 1.28 g of regenerated plant protein, 10 mL of DMAC, and 10 mL of TMF solution were added. A magnetic stir bar was then added, and the mixture was stirred at 50°C for 5 hours. The prepared spinning solution was then electrospun using a spinning device under conditions of an electric field strength of 10 kV, a rotation speed of 500 r / min, and a collection distance of 6 cm to obtain the desired fiber morphology.

[0116] The spun fibers were calcined once at a temperature of 255℃, with the heating rate controlled at 2℃ / min. The temperature was maintained at 255℃ for an appropriate holding time (40 min) to ensure sufficient evaporation of the organic solvent and improvement of the fiber structure. After calcination, the fibers were slowly cooled (at a cooling rate of 2℃ / min) to avoid structural damage due to rapid temperature changes, resulting in a thin, flexible biomass thermal conductive film material with a thickness of 4.5 μm.

[0117] The thermal conductivity test was the same as in Example 1, and the measured thermal conductivity of the material was 10.58 W / (m·K).

[0118] The obtained product was tested according to ASTM D882, with a test speed of 500 mm / min. The tensile strength was 4.09 MPa and the elongation at break was 398%.

[0119] The contact angle performance test was the same as in Example 1, and the water contact angle of the material was measured to be 62°.

[0120] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing an ultrathin, lightweight, and flexible biomass thermal conductive film material, characterized in that, Includes the following steps: (1) A spinning solution is prepared by uniformly mixing graphene oxide solution, biomass raw materials, and solvent; the biomass raw materials are composed of lignin cellulose, chitin, sodium alginate, and regenerated plant protein, with a molar ratio of 1:1:1~2:0~2; the amount of graphene oxide added is 1.6%-3.0% of the total mass of the biomass raw materials; (2) The mixed spinning solution is electrospun into a film using a spinning device; (3) The membrane is subjected to gradient calcination to obtain an ultrathin and flexible biomass thermal conductive membrane material; The gradient calcination is divided into a pre-oxidation temperature range and a carbonization temperature range. The pre-oxidation temperature range is 220-300℃, with a heating rate of 0.5-5℃ / min and a time of 40min. The carbonization temperature range is 300-800℃, with a heating rate of 0.5-20℃ / min and a time of 30min. After calcination, the temperature is cooled to room temperature at a rate of 2℃ / min.

2. The method for preparing the ultrathin, flexible biomass thermal conductive film material according to claim 1, characterized in that, The solvent mentioned in step (1) is one or a mixture of water, N,N-dimethylformamide, N,N-dimethylacetamide, and 2,2,5,5-tetramethyltetrahydrofuran-3-one.

3. The method for preparing the ultrathin, flexible biomass thermal conductive film according to claim 1, characterized in that, The mixing conditions described in step (1) are: magnetic heating and stirring, stirring temperature of 30-100℃, and stirring time of 60-720min.

4. The method for preparing the ultrathin, flexible biomass thermal conductive film material according to claim 1, characterized in that, The method for preparing the graphene oxide solution in step (1) is as follows: graphene oxide and N,N-dimethylformamide are mixed and dispersed in an ultrasonic bath for 4-6 hours.

5. The method for preparing the ultrathin, flexible biomass thermal conductive film material according to claim 1, characterized in that, The spinning conditions described in step (2) are: electric field strength of 8-20kV, rotation speed of 300-800r / min, collection distance of 5-10cm, pore size of 0.6μm, and spinning speed of 0.5mL / h.

6. An ultrathin, flexible biomass thermal conductive film material prepared by the method according to any one of claims 1-5.

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