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

Abstract

The invention belongs to the technical field of organic materials, and particularly relates to a multifunctional phase change composite material with good flexibility, efficient heat management and efficient energy storage performance and a preparation method and application thereof. The phase change composite material disclosed by the invention is a multifunctional phase change material which is good in conductivity, leakproof and flexible and is obtained by taking cotton as a substrate and carrying out auto-polymerization and in-situ chemical silver plating of polydopamine (PDA) on the basis of the cotton, and then carbonizing and packaging paraffin. The raw materials are easy to obtain, the price is low, the experiment is simple and convenient, and the obtained phase change material has the properties of heat energy storage and conversion, heat stability, high conductivity, leakage prevention, flexibility, photo-thermal conversion and the like. The cheap and easily available phase change material provides a way for energy storage and conversion materials, and also provides solution suggestions for effective thermal management of lithium ions.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic materials, and in particular relates to a multifunctional phase-change composite material with good flexibility, efficient thermal management, and efficient energy storage performance, as well as a preparation method and application thereof. Background Art

[0002] Due to the expected rise in energy demand in the world and the dependence on fossil fuels, the development of new renewable energy sources has become a pressing issue for us. It is no surprise that the huge demand for energy will naturally turn to different sustainable and renewable energy sources such as wind, solar and biomass. Solar energy is considered to be one of the most desirable renewable alternative energy sources. Encapsulated phase change materials (PCMs) offer a viable avenue for the storage and release of solar thermal energy in the future, as they are able to store and release large amounts of thermal energy seamlessly during phase changes without producing any harmful emissions. They have a high efficiency in storing thermal energy under isothermal conditions with only a very small temperature difference between the stored and released energy. Due to the many advantages of PCMs, they have attracted attention from various fields such as building materials, electronic devices and solar energy systems, and aerospace.

[0003] Solid-liquid organic PCM is one of the most promising energy storage methods, with high latent heat capacity and suitable phase transition temperature, which can be easily adjusted by mixing. In addition, solid-liquid organic PCM has many ideal properties, including chemical and thermal stability, biodegradability, non-toxicity, excellent corrosion resistance and competitive price. However, solid-liquid organic PCM has two obvious disadvantages, namely leakage during phase transition and low thermal conductivity. Leakage and low thermal conductivity greatly limit the practical application of PCM.

[0004] Biomass-derived carbon materials have been found to be promising encapsulation matrices with significant porous structures, large surface areas, and biomass-derived carbon composites have the advantages of low density, wide sources, relatively low cost, environmental protection, and high thermal stability and thermal conductivity. Therefore, they have been widely studied in the field of energy storage. Summary of the invention

[0005] The purpose of the present invention is to provide a multifunctional phase change composite material with good flexibility, efficient light-heat conversion, electrothermal conversion and efficient thermal management of lithium ions, and a preparation method and application thereof.

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

[0007] The multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance is a multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance. The conductive and thermal conductive network is obtained by encapsulating paraffin on the basis of the bioporous carbon.

[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 of the above items comprises 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 fiber and in-situ chemical silver plating; subsequently, CCPAX material with a hollow carbon fiber three-dimensional network structure is obtained by carbonization; finally, paraffin is adsorbed by vacuum impregnation to prepare CCPAX material @PW.

[0010] Furthermore, the above-mentioned preparation method comprises the following specific steps:

[0011] 1) Treat commercial cotton with 7% NaOH solution, soak it for 2 hours and then wash it with water to neutralize it, which is recorded as C cotton;

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

[0014] 4) CPAX was carbonized in a tube furnace, then immersed in a paraffin solution and adsorbed in a vacuum oven for 12 h, and then placed in a forced air oven at 80 °C until the cotton volume reached a constant weight, thereby obtaining 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-mentioned preparation method, in step 4), the carbonization conditions are: reacting in a tube furnace at 900° C. for 2 hours under N2 atmosphere.

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

[0021] The beneficial effects of the present invention are:

[0022] 1. The present invention has readily available raw materials, low price, simple operation, and improves the inherent defects of phase change materials such as low conductivity, leakage, and rigidity.

[0023] 2. The good flexibility of the present invention is due to the selection of more flexible cotton as the raw material for preparing bioporous carbon, which makes it possible to fully wrap the lithium-ion battery.

[0024] 3. The packaging method of the phase change material of the present invention is based on biological porous carbon prepared from cotton.

[0025] 4. The material used in the present 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 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 the thermal management of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a light-to-heat conversion curve diagram of the phase change composite materials prepared in Example 6, Example 7, Example 8 and Example 9.

[0028] Figure 2 It is the electrothermal conversion curve diagram of the phase change composite materials prepared in Example 6, Example 7, Example 8 and Example 9.

[0029] Figure 3 It is a curve comparison of the surface temperature increase of a bare cell and a lithium-ion battery wrapped with the phase change composite material prepared in Example 9 during discharge. DETAILED DESCRIPTION

[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 h, and then washed with water to neutralize the cotton, which was recorded as C cotton.

[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; dopamine hydrochloride was then 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 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 minutes; then 5 g of glucose and potassium sodium tartrate (glucose: potassium sodium tartrate = 3:1) were added and stirred at 40°C for 60 minutes 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 minutes; then 5 g of glucose and potassium sodium tartrate (glucose: potassium sodium tartrate = 3:1) were added and stirred at 40°C for 90 minutes 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 immersed in a paraffin solution and adsorbed in a vacuum oven for 12 hours; then placed in a blast oven at 80° C. until the volume of the cotton reached a constant weight, thereby obtaining 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 in a N2 atmosphere for 2 h; then it was immersed in a paraffin solution and adsorbed in a vacuum oven for 12 h; then it was placed in a blast oven at 80°C until the cotton volume reached a constant weight, thereby 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 in a N2 atmosphere for 2 h; then it was immersed in a paraffin solution and adsorbed in a vacuum oven for 12 h; then it was placed in a blast oven at 80°C until the cotton volume reached a constant weight, thereby 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 in a N2 atmosphere for 2 hours; then it was immersed in a paraffin solution and adsorbed in a vacuum oven for 12 hours; then it was placed in a blast oven at 80°C until the cotton volume reached a constant weight, thereby obtaining CCPA90@PW.

[0057] Figure 1 The comparison of photothermal conversion is shown. It is not difficult to find that as the silver plating time increases and the silver plating content increases, the surface temperature rise effect during photothermal conversion is also better. This is because the high content of Ag particles improves the heat transfer and increases the rate of photothermal conversion, resulting in a higher temperature.

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

[0059] Example 10 Application

[0060] CCPA90@PW with a thickness of 5 mm was used as a heat dissipation medium to completely wrap the commercial 18650 lithium-ion battery, thereby constructing a battery thermal management system. Both CCPA90@PW-wrapped and unwrapped lithium-ion batteries were discharged at a constant ambient temperature of 22°C and the real-time temperature changes were recorded.

[0061] Figure 3 The surface temperature comparison of bare cells and CCPA90@PW wrapped lithium-ion batteries during discharge is shown. As can be seen from the figure, the maximum temperature of the lithium-ion battery wrapped with CCPA90@PW during discharge is relatively low, reaching only about 30°C at its highest, which is completely within the temperature range of safe discharge. The maximum temperature of the bare cell during 2C (1C=2500mA) discharge is around 50°C, which is completely within the dangerous temperature range of the battery. Therefore, the CCPA90@PW phase change composite material prepared by the present invention has excellent heat storage function and has certain application prospects in the field of thermal management of batteries in the future.

[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, efficient thermal management and efficient energy storage performance, characterized in that: The multifunctional phase change composite material is a multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance obtained by silver-plating and carbonizing biological carbon fibers and encapsulating paraffin on the basis of the biological porous carbon.

2. The multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance according to claim 1, characterized in that: The biochar is cotton.

3. The method for preparing the multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance according to claim 2, characterized in that: The method comprises the following steps: first, 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 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, paraffin is adsorbed by vacuum impregnation to prepare CCPAX material@PW.

4. The preparation method according to claim 3, characterized in that: The specific steps are as follows: 1) Treat commercial cotton with 7% NaOH solution, soak it for 2 hours and then wash it with water to neutralize it, which is recorded as C cotton; 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; 3) adding silver nitrate to water to form a silver nitrate solution, then adding C@PDA to react for 30 min, then adding a mixture of 5 g glucose and potassium sodium tartrate, and stirring at 40 °C to obtain CPAX; 4) CPAX was carbonized in a tube furnace, then immersed in a paraffin solution and adsorbed in a vacuum oven for 12 h, and then placed in a forced air oven at 80 °C until the cotton volume reached a constant weight, thereby obtaining CCPAX@PW.

5. The preparation method according to claim 4, characterized in that: In step 2), the concentration of the PDA solution is 2 mg / mL.

6. The preparation method according to claim 4, characterized in that: In step 3), the concentration of the silver nitrate solution is 30 mg / mL.

7. The preparation method according to claim 4, characterized in that: In step 3), the mass ratio of glucose to potassium sodium tartrate is 3:

1.

8. The preparation method according to claim 4, characterized in that: In step 3), the stirring time is 30 min, 60 min or 90 min.

9. The preparation method according to claim 4, characterized in that: In step 4), the carbonization conditions are: reacting in a tube furnace at 900° C. for 2 h under N2 atmosphere.

10. Use of the multifunctional phase change composite material with good flexibility, efficient thermal management and efficient energy storage performance as claimed in claim 1 or 2 in wrapping lithium-ion batteries.

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