Multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance, preparation method and application thereof

Abstract

The present application belongs to the technical field of organic materials, and particularly relates to a multifunctional phase change composite material with good flexibility, high efficient heat management and high efficient energy storage performance as well as a preparation method and application thereof.The phase change composite material of the present application is a multifunctional phase change material with good conductivity, leakage prevention and flexibility, which is obtained by taking cotton as a substrate, self-polymerizing and in-situ chemical plating silver on the basis of the cotton, then carbonizing and encapsulating paraffin wax.The raw materials of the present application are easy to obtain, low in price and simple in experiment, and the obtained phase change material has the performances of heat energy storage and conversion, heat stability, high conductivity, leakage prevention, flexibility and photo-thermal conversion, etc.This cheap and easy-to-obtain phase change material provides a way for energy storage and conversion materials, and also provides a solution for effective heat management of lithium ions.

Description

Technical Field

[0001] This invention belongs to the field of organic materials technology, and particularly relates to a multifunctional phase change composite material with good flexibility, efficient thermal management, and efficient energy storage performance, as well as its preparation method and application. Background Technology

[0002] With anticipated increases in global energy demand and reliance on fossil fuels, developing new renewable energy sources has become an urgent issue. Undoubtedly, the enormous demand for energy will naturally shift towards various sustainable and renewable energy sources, such as wind, solar, and biomass energy. Solar energy is considered one of the most desirable renewable alternatives. Encapsulated phase change materials (PCMs) offer a viable pathway for the storage and release of solar thermal energy in the future because they can seamlessly store and release large amounts of heat energy during phase change without producing any harmful emissions. They exhibit high efficiency in storing heat energy under isothermal conditions, with only a very small temperature difference between the stored and released energy. Due to their numerous advantages, PCMs have attracted attention in various fields, such as building materials, electronic devices and solar energy systems, and the aerospace industry.

[0003] Solid-liquid organic PCMs are among the most promising energy storage methods, possessing high latent heat capacity and suitable phase change temperature, and are easily regulated through mixing. Furthermore, solid-liquid organic PCMs exhibit a variety of desirable properties, including chemical and thermal stability, biodegradability, non-toxicity, excellent corrosion resistance, and competitive pricing. However, solid-liquid organic PCMs have two significant drawbacks: leakage during phase change and low thermal conductivity. These two factors severely limit the practical application of PCMs.

[0004] Biocarbon materials have been found to be promising encapsulation matrices, possessing a significant porous structure, large surface area, and biomass-derived carbon composites offer advantages such as low density, wide availability, relatively low cost, environmental friendliness, and high thermal stability and conductivity. Therefore, they have been extensively studied in the field of energy storage. Summary of the Invention

[0005] The purpose of this invention is to provide a multifunctional phase change composite material with good flexibility, high efficiency in photothermal conversion, electrothermal conversion and high efficiency in lithium-ion thermal management, as well as its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The multifunctional phase change composite material with good flexibility, efficient thermal management, and efficient energy storage performance is made by using bioporous carbon obtained by silver plating and carbonization of bio-carbon fibers as a conductive and thermally conductive network, and then encapsulating paraffin on the bioporous carbon base to obtain a multifunctional phase change composite material with good flexibility, efficient thermal management, and efficient energy storage performance.

[0008] Preferably, the biochar is cotton.

[0009] The preparation method of the multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance described in any one of the above-mentioned methods includes the following steps: First, commercially available cotton is treated with an alkaline solution to induce cotton fiber expansion; then, CPAX material is prepared by self-polymerization of polydopamine PDA on cotton fibers and in-situ chemical silver plating; subsequently, CCPAX material with a hollow carbon fiber three-dimensional network structure is obtained by carbonization; finally, CCPAX material @PW is prepared by adsorbing paraffin by vacuum impregnation.

[0010] Furthermore, the specific steps of the above preparation method are as follows:

[0011] 1) Treat commercially available cotton with 7% NaOH solution, soak it for 2 hours, then wash it with water until it is neutral, and label it as cotton C;

[0012] 2) Add tris(hydroxymethyl)aminomethane hydrochloride to water and adjust the pH to 8.5, then add dopamine hydrochloride to form a PDA solution, add C cotton and react for 12 hours to obtain C@PDA;

[0013] 3) Add silver nitrate to water to form a silver nitrate solution, then add C@PDA and react for 30 min, then add a mixture of 5 g glucose and potassium sodium tartrate, and stir at 40 °C to obtain CPAX;

[0014] 4) Carbonize CPAX in a tube furnace, then soak it in paraffin solution and adsorb it in a vacuum oven for 12 hours. Then place it in an 80°C forced-air oven until the cotton volume is constant to obtain CCPAX@PW.

[0015] Furthermore, in the above preparation method, in step 2), the concentration of the PDA solution is 2 mg / mL.

[0016] Furthermore, in the above preparation method, in step 3), the concentration of the silver nitrate solution is 30 mg / mL.

[0017] Furthermore, in the above preparation method, in step 3), the mass ratio of glucose to potassium sodium tartrate is 3:1.

[0018] Furthermore, in the above preparation method, in step 3), the stirring time is 30 min, 60 min, or 90 min.

[0019] Furthermore, in the above preparation method, step 4), the carbonization conditions are: reacting in a tube furnace at 900°C for 2 hours under a N2 atmosphere.

[0020] The application of the multifunctional phase change composite material with good flexibility, efficient thermal management, and efficient energy storage performance described above in the encapsulation of lithium-ion batteries.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention uses readily available and inexpensive raw materials, is easy to operate, and improves upon the inherent defects of phase change materials such as low conductivity, leakage, and rigidity.

[0023] 2. The good flexibility of this invention is due to the selection of cotton, which has greater flexibility, as the raw material for preparing bioporous carbon, which makes it possible to fully encapsulate lithium-ion batteries.

[0024] 3. The encapsulation method of the phase change material in this invention is based on bioporous carbon prepared from cotton.

[0025] 4. The material used in this invention is bio-carbon fiber. Silver plating on the fiber material can enhance its conductivity, thereby achieving efficient electrothermal conversion and photothermal conversion of the phase change composite material.

[0026] 5. The phase change material of this invention has comprehensive properties such as thermal energy storage and conversion, thermal stability, high conductivity, leakage prevention and flexibility, and has certain application value in the thermal management of lithium-ion batteries. Attached Figure Description

[0027] Figure 1 These are the photothermal conversion curves of the phase change composite materials prepared in Examples 6, 7, 8 and 9.

[0028] Figure 2 The graphs show the electrothermal conversion curves of the phase change composite materials prepared in Examples 6, 7, 8 and 9.

[0029] Figure 3 This is a comparison graph showing the surface temperature rise during discharge of a bare battery and a lithium-ion battery wrapped with the phase change composite material prepared in Example 9. Detailed Implementation

[0030] Example 1C: Preparation of Cotton

[0031] The preparation method is as follows:

[0032] Commercially available cotton was treated with 7% NaOH solution, soaked for 2 hours, and then washed with water until neutral. This was labeled as cotton C.

[0033] Example 2: Preparation of C@PDA

[0034] The preparation method is as follows:

[0035] First, 1.2114 g of tris(hydroxymethyl)aminomethane hydrochloride was added to 1000 mL of water and the pH was adjusted to 8.5; then, dopamine hydrochloride was added to form a 2 mg / mL PDA solution; finally, the C cotton prepared in Example 1 was added and reacted for 12 h to obtain C@PDA.

[0036] Example 3: Preparation of CPA30

[0037] The preparation method is as follows:

[0038] First, silver nitrate was added to water to form a silver nitrate solution with a concentration of 30 mg / mL; then, C@PDA prepared in Example 2 was added and reacted for 30 min; then, 5 g of glucose and potassium sodium tartrate (glucose: potassium sodium tartrate = 3:1) were added, and the mixture was stirred at 40 °C for 30 min to obtain CPA30.

[0039] Example 4: Preparation of CPA60

[0040] The preparation method is as follows:

[0041] First, silver nitrate was added to water to form a silver nitrate solution with a concentration of 30 mg / mL; then, C@PDA prepared in Example 2 was added and reacted for 30 min; then 5 g of glucose and potassium sodium tartrate (glucose: potassium sodium tartrate = 3:1) were added, and the mixture was stirred at 40 °C for 60 min to obtain CPA60.

[0042] Example 5: Preparation of CPA90

[0043] The preparation method is as follows:

[0044] First, silver nitrate was added to water to form a silver nitrate solution with a concentration of 30 mg / mL; then, C@PDA prepared in Example 2 was added and reacted for 30 min; then, 5 g of glucose and potassium sodium tartrate (glucose: potassium sodium tartrate = 3:1) were added, and the mixture was stirred at 40 °C for 90 min to obtain CPA90.

[0045] Example 6: Preparation of C@PW

[0046] The preparation method is as follows:

[0047] The C cotton prepared in Example 1 was soaked in a paraffin solution and adsorbed in a vacuum oven for 12 hours; then it was placed in an 80°C forced-air oven until the cotton volume was constant to obtain C@PW.

[0048] Example 7: Preparation of CCPA30@PW

[0049] The preparation method is as follows:

[0050] First, the CPA30 prepared in Example 3 was reacted in a tube furnace at 900°C under N2 atmosphere for 2 hours; then it was soaked in paraffin solution and adsorbed in a vacuum oven for 12 hours; then it was placed in an 80°C forced-air oven until the cotton volume was constant, thus obtaining CCPA30@PW.

[0051] Example 8: Preparation of CCPA60@PW

[0052] The preparation method is as follows:

[0053] First, the CPA60 prepared in Example 4 was reacted in a tube furnace at 900°C under N2 atmosphere for 2 hours; then it was soaked in paraffin solution and adsorbed in a vacuum oven for 12 hours; then it was placed in an 80°C forced-air oven until the cotton volume was constant, thus obtaining CCPA60@PW.

[0054] Example 9: Preparation of CCPA90@PW

[0055] The preparation method is as follows:

[0056] First, the CPA90 prepared in Example 5 was reacted in a tube furnace at 900°C under N2 atmosphere for 2 hours; then it was soaked in paraffin solution and adsorbed in a vacuum oven for 12 hours; then it was placed in an 80°C forced-air oven until the cotton volume was constant, thus obtaining CCPA90@PW.

[0057] Figure 1 The comparison of photothermal conversion is shown. It is easy to see that with longer silver plating time and higher silver content, the surface temperature rise during photothermal conversion is more effective. This is because a higher content of Ag particles improves heat transfer, increases the rate of photothermal conversion, and thus results in a higher temperature.

[0058] Figure 2 The comparison of electrothermal conversion is shown. As can be seen from the figure, compared to C@PW and the composite material with a shorter silver plating time, CCPA90@PW exhibits a faster heating rate and a higher temperature value. This is because the increased Ag content provides more electron channels, resulting in faster heat transfer and thus a higher surface temperature.

[0059] Example 10 Application

[0060] A 5mm thick CCPA90@PW heat dissipation medium was used to completely encapsulate a commercial 18650 lithium-ion battery, thus constructing a battery thermal management system. Both the CCPA90@PW-encapsulated and unencapsulated lithium-ion batteries were discharged at a constant ambient temperature of 22℃, and real-time temperature changes were recorded.

[0061] Figure 3 The figure shows a comparison of the surface temperatures of a bare battery and a lithium-ion battery coated with CCPA90@PW during discharge. As can be seen from the figure, the highest temperature of the CCPA90@PW-coated lithium-ion battery during discharge is relatively low, reaching only around 30°C, which is well within the safe discharge temperature range. In contrast, the highest temperature of the bare battery during 2C (1C = 2500mA) discharge is around 50°C, which is well within the dangerous temperature range for batteries. Therefore, the CCPA90@PW phase change composite material prepared in this invention has excellent heat storage capabilities and shows promising application prospects in the field of battery thermal management.

[0062] In summary, the phase change composite material of the present invention has comprehensive properties such as thermal energy storage and conversion, thermal stability, high conductivity, leakage prevention and flexibility, and has certain application value in thermal management.

Claims

1. A multifunctional phase change composite material with good flexibility, high efficiency heat management, and high efficiency energy storage performance, characterized in that, The preparation method of the multifunctional phase change composite material with good flexibility, high efficient heat management and high efficient energy storage performance comprises the following steps: firstly, commercially available cotton is treated with an alkaline solution to induce cotton fiber swelling; then, CPAX material is prepared by self-polymerization of polydopamine PDA on the cotton fiber and in-situ chemical silver plating; subsequently, CCPAX material with a hollow carbon fiber three-dimensional network structure is obtained by carbonization; finally, CCPAX material@PW is prepared by vacuum impregnation method to adsorb paraffin. 2.The multifunctional phase change composite material with good flexibility, high efficiency heat management and high efficiency energy storage performance according to claim 1, wherein, The specific steps of the preparation method are as follows: 1) commercially available cotton is treated with a 7% NaOH solution, soaked for 2 h and then washed to neutral, denoted as C cotton; 2) in water, trimethylol aminomethane hydrochloride is added and the pH is adjusted to 8.5, then dopamine hydrochloride is added to form a PDA solution, C cotton is added and reacted for 12 h to obtain C@PDA; 3) in water, silver nitrate is added to form a silver nitrate solution, C@PDA is added and reacted for 30 min, then a mixture of 5 g glucose and potassium sodium tartrate is added and stirred at 40 ℃ to obtain CPAX; 4) CPAX is placed in a tube furnace for carbonization, then soaked in a paraffin solution and adsorbed in a vacuum oven for 12 h, and then placed in an 80 ℃ air oven until the volume of the cotton is constant to obtain CCPAX@PW. 3.The multifunctional phase change composite material with good flexibility, high efficiency heat management and high efficiency energy storage performance according to claim 2, characterized in that, In step 2), the concentration of the PDA solution is 2 mg / mL. 4.The multifunctional phase change composite material with good flexibility, high efficiency heat management and high efficiency energy storage performance according to claim 2, wherein, In step 3), the concentration of the silver nitrate solution is 30 mg / mL. 5.The multifunctional phase change composite material with good flexibility, high efficiency thermal management, and high efficiency energy storage performance according to claim 2, wherein, In step 3), the mass ratio of glucose to potassium sodium tartrate is 3:

1. 6.The multifunctional phase change composite material with good flexibility, high efficiency heat management and high efficiency energy storage performance according to claim 2, wherein, In step 3), the stirring time is 30 min, 60 min or 90 min. 7.The multifunctional phase change composite material with good flexibility, high efficiency heat management and high efficiency energy storage performance according to claim 2, wherein, In step 4), the carbonization conditions are as follows: reaction in a tube furnace at 900 ℃ under N2 atmosphere for 2 h.

8. Application of the multifunctional phase change composite material with good flexibility, high efficient heat management and high efficient energy storage performance in claim 1 in wrapping lithium ion batteries.

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