A high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells and its preparation method

Abstract

This invention provides a high-efficiency heat dissipation backsheet for rare-earth-based photovoltaic cells and its preparation method. The heat dissipation backsheet includes a rare-earth-based PET composite material layer and a fluorine-containing layer coated on the surface of the rare-earth-based PET composite material layer. The rare-earth-based PET composite material comprises, by weight, 60-80 parts of PET resin, 18-35 parts of functional PET masterbatch, and 2-3 parts of antioxidant. The functional PET masterbatch is prepared from raw materials including NH2-PET resin, modified flaky lanthanum cerium oxide, and a dispersant. The backsheet described in this invention can achieve efficient heat dissipation for solar cells, thereby improving cell performance and extending lifespan.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic technology, and in particular relates to a high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells and its preparation method. Background Technology

[0002] Solar cells are highly sensitive to temperature changes; high temperatures significantly reduce their photoelectric conversion efficiency and lifespan. Existing indirect cooling technologies suffer from problems such as large pressure drops, uneven heat transfer, and high energy consumption, while direct contact heat exchange technologies require high stability of the cooling medium. Radiative cooling materials are relatively common in the research field, and while these materials often achieve good cooling effects at night, their heat dissipation performance under sunlight is less than satisfactory. Therefore, the photoelectric conversion efficiency of solar cells is severely limited by high temperatures. Summary of the Invention

[0003] In view of this, the present invention aims to propose a high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells and its preparation method to solve the heat dissipation problem of heat dissipation backplate. The backplate has the characteristics of high thermal conductivity, high reflectivity and high emissivity, which can effectively achieve heat dissipation under sunlight. Moreover, the backplate is a passive heat dissipation technology with the advantages of low cost, high stability and no additional energy consumption.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] A high-efficiency heat dissipation backsheet for rare-earth-based photovoltaic cells includes a rare-earth-based PET composite material layer and a fluorine-containing layer coated on the surface of the rare-earth-based PET composite material layer; wherein, the rare-earth-based PET composite material comprises, by mass parts: 60-80 parts of PET resin, 18-35 parts of functional PET masterbatch, and 2-3 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including modified flake lanthanum cerium oxide, NH2-PET resin, and dispersant in a mass ratio of 30-40:46-60:8-14.

[0006] Blending flake lanthanum oxide directly with PET resin results in uneven distribution of lanthanum oxide and weak affinity between lanthanum oxide and resin. Therefore, it is necessary to modify both PET resin and flake lanthanum oxide separately. At the same time, a dispersant is added during the extrusion blending process to enhance the adhesion between lanthanum oxide and PET resin, making it less prone to sedimentation and significantly improving dispersibility.

[0007] Furthermore, the NH2-PET resin was prepared by the following method:

[0008] S11. Place 2-aminoterephthalic acid in a vacuum oven to dry;

[0009] S12. Add 4A molecular sieve to ethylene glycol, soak overnight, and purify ethylene glycol;

[0010] S13. Add 2-aminoterephthalic acid, purified ethylene glycol and antimony glycol to the flask, and purge the system with nitrogen to replace the air.

[0011] S14. Insert a water separator and a stirring paddle into the mouth of the flask, and conduct an oil bath to carry out esterification, pre-condensation and final condensation reactions in sequence.

[0012] S15. After the reaction, nitrogen gas is used to break the vacuum, and the melt is rapidly cooled with water to obtain NH2-PET resin.

[0013] Furthermore, in S11, drying at 120-180℃ for 2-5 hours reduces the water content to below 0.01%.

[0014] In S12, the soaked ethylene glycol is filtered, and after filtration, it is distilled under reduced pressure at 100°C to collect the distilled ethylene glycol.

[0015] In S14, the esterification reaction temperature is 250℃ and the stirring rate is 200-350 r / min;

[0016] After the water separator collects more than 6.9g of water, the system pressure is slowly reduced to 5kPa to carry out pre-condensation. The oil bath temperature is adjusted to 270℃ and the reaction lasts for 1.5-2 hours.

[0017] Reduce the pressure to below 50 Pa to carry out final polycondensation, adjust the oil bath temperature to 280-290℃, and let the reaction continue for 2-3 hours.

[0018] Furthermore, the specific preparation method of NH2-PET resin is as follows:

[0019] 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours to reduce the water content to less than 0.01%.

[0020] 2) Add 5-10g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100℃ to collect the distilled ethylene glycol.

[0021] 3) Weigh 36g of dried 2-aminoterephthalic acid, 14.88-19.84g of purified ethylene glycol and 15-17mg of antimony glycol and add them to a flask. Purge the system with nitrogen to replace the air.

[0022] 4) Insert a water separator and a stirring paddle into the mouth of the flask, and place it in an oil bath at a temperature of 250℃ and a stirring rate of 200-350r / min to carry out the esterification reaction.

[0023] 5) After the water distributor has collected more than 6.9g of water, connect the system to the vacuum pump and slowly reduce the system pressure to 5kPa.

[0024] 6) Adjust the oil bath temperature to 270℃ and continue the reaction for 1.5-2 hours to carry out pre-condensation.

[0025] 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 280-290℃. Continue the reaction for 2-3 hours to carry out the final polycondensation.

[0026] 8) After the reaction, nitrogen gas is used to break the vacuum and the melt is rapidly cooled with water to obtain NH2-PET resin.

[0027] Furthermore, the modified plate-like lanthanum cerium oxide includes three particle sizes: 1: 0.1-2 μm, D: ... 50 =1μm, particle size 2: 2-8μm, D 50 =5μm, particle size 3: 12-18μm, D 50 =15μm; the ratio of the three particle sizes is particle size 1: particle size 2: particle size 3 = 1:1.5:1, and the thickness of the modified lanthanum cerium oxide plates with the three particle sizes is 20-400nm.

[0028] Furthermore, the modified plate-like lanthanum cerium oxide was prepared by the following method:

[0029] I. Preparation of sheet-like lanthanum cerium oxide:

[0030] S21. Weigh out cerium carbonate and lanthanum carbonate in proportion, and dissolve lanthanum carbonate and cerium carbonate in nitric acid solution to obtain lanthanum cerium nitrate solution.

[0031] S22. Mix the lanthanum nitrate and cerium nitrate solution and the surfactant solution in a certain proportion, and then add ammonium oxalate solution until precipitation is complete;

[0032] S23. The precipitate is filtered, washed and dried to obtain lanthanum cerium oxalate powder;

[0033] S24. Lanthanum oxalate was calcined at 600-1000℃ for 3 hours to obtain flaky lanthanum oxalate powder.

[0034] II. Modified flaky lanthanum and cerium oxide

[0035] The prepared lanthanum cerium oxide sheets were modified using silane coupling agents.

[0036] Furthermore, in step I, during the preparation of sheet-like lanthanum cerium oxide:

[0037] In S21, the molar ratio of cerium carbonate to lanthanum carbonate is (90-9):1, and the concentration of the resulting lanthanum nitrate cerium solution is 0.2-0.8 mol / L.

[0038] In S22, the surfactant is one or more of sodium oleate, polyallyl ammonium chloride, hexadecyltrimethylammonium bromide, and sodium dodecyl sulfate, and the concentration of the surfactant is 3-20 g / L.

[0039] Lanthanum nitrate solution and surfactant solution are mixed at a mass ratio of 1:(1.6-2.8). After mixing, the lanthanum nitrate solution and surfactant solution are heated and stirred at 40-120℃ with a rotation speed of 30-100 r / min. By controlling the rotation speed, flake-shaped lanthanum nitrate solution of different particle sizes can be obtained. When the rotation speed is 20-40 r / min, a particle size of 3 is obtained; when the rotation speed is 50-70 r / min, a particle size of 2 is obtained; and when the rotation speed is 90-110 r / min, a particle size of 1 is obtained.

[0040] The concentration of ammonium oxalate solution is 0.36-0.89 mol / L. After adding ammonium oxalate solution until precipitation is complete, continue the reaction for 2-5 hours, and then allow it to settle at room temperature for 8-24 hours.

[0041] Furthermore, the specific steps for preparing plate-like lanthanum cerium oxide are as follows:

[0042] 1) Weigh cerium carbonate and lanthanum carbonate in a molar ratio of (90-9):1;

[0043] 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water, and prepare a 0.2-0.8 mol / L lanthanum and cerium nitrate solution;

[0044] 3) Dissolve a small amount of surfactant in deionized water to prepare a surfactant solution of 3-20 g / L;

[0045] 4) Dissolve ammonium oxalate in deionized water to prepare an ammonium oxalate solution of 0.36-0.89 mol / L;

[0046] 5) Mix lanthanum nitrate solution and surfactant solution at a mass ratio of 1:(1.6-2.8). Pour the mixed solution into a flask, heat and stir at 40-120℃ at a speed of 30-100 r / min, add ammonium oxalate solution until precipitation is complete, and continue the reaction for 2-5 h. Then allow it to settle at room temperature for 8-24 h.

[0047] 6) The precipitate was filtered, washed and dried to obtain lanthanum cerium oxalate powder;

[0048] 7) Calcine lanthanum oxalate at 600-1000℃ for 3 hours to obtain flaky lanthanum oxalate powder.

[0049] Furthermore, step II, modifying the lamellar lanthanum oxide, includes the following steps:

[0050] S31. Mix and stir the flake lanthanum cerium oxide, deionized water, ethanol and ammonia until completely dispersed, and then heat.

[0051] S32. Mix ethanol and silane coupling agent to obtain silane coupling agent solution;

[0052] S33. Add the silane coupling agent solution dropwise to the solution system obtained in step S31 and react. After the reaction, allow the system to stand and cool, centrifuge, wash, and dry.

[0053] Furthermore, the silane coupling agent is one of 3-isocyanopropyltrimethoxysilane, 3-isocyanopropyltriethoxysilane, and 3-isocyanopropylmethyldimethoxysilane.

[0054] Furthermore, the specific preparation method for modified plate-like lanthanum cerium oxide is as follows:

[0055] 1) Add 10g of flake lanthanum cerium oxide, 50-80mL of deionized water, 250-400mL of ethanol and 15-25mL of ammonia to the flask, and stir until completely dispersed;

[0056] 2) Turn on the heating, and set the reaction temperature to 40-80℃;

[0057] 3) Measure 200 mL of ethanol, add 1-2 mL of silane coupling agent to it, and prepare a homogeneous solution;

[0058] 4) After the temperature stabilizes, add the ethanol solution of silane coupling agent dropwise to the flask and continue the reaction for 6-10 hours;

[0059] 5) After the reaction, allow the system to stand and cool, then centrifuge and wash with ethanol more than 5 times. Place it in a vacuum oven and dry it under vacuum at 50°C.

[0060] Furthermore, the thickness of the rare earth-based PET composite layer is 200-400 μm, the thickness of the fluorine-containing layer is 20-40 μm, and the material of the fluorine-containing layer is polyvinylidene fluoride;

[0061] The antioxidant is one or more of antioxidant 1076, antioxidant 3114, and antioxidant 245;

[0062] The dispersant is one or more of DYD-9806, GLYCOLUBE P, and AC540A.

[0063] This invention also provides a method for preparing a high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells as described above, the method comprising the following steps:

[0064] I. Preparation of Functional PET Masterbatch

[0065] Modified flake lanthanum cerium oxide, NH2-PET resin, and dispersant are mixed in a high-speed mixer to ensure uniform mixing and form a blend. The blend is then added to a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch.

[0066] 2. PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast onto a cooling drum for rapid cooling to form a rare earth-based PET composite material layer.

[0067] 3. Apply polyvinylidene fluoride to both sides of the rare earth-based PET composite material layer and microwave cure for 10-20 minutes to form a fluorine-containing layer, thus obtaining a high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells.

[0068] Furthermore, the temperatures of each zone of the twin-screw extruder are 240, 255, 255, 270, and 270°C, the die temperature is 270°C, and the feeding rate is 300 g / min.

[0069] Compared with existing technologies, the high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells and its preparation method described in this invention have the following advantages:

[0070] The rare-earth-based photovoltaic cell high-efficiency heat dissipation backsheet described in this invention utilizes a passive heat dissipation method, offering advantages such as low cost, high stability, and no additional energy consumption. Compared to conventional PET backsheets, this backsheet has higher thermal conductivity, reflectivity, and emissivity, enabling effective heat dissipation of the solar cell and improving its output power. Attached Figure Description

[0071] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0072] Figure 1 This is a schematic diagram of the structure of the high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells according to an embodiment of the present invention;

[0073] Figure 2 This is a side sectional view of the heat dissipation evaluation system;

[0074] Figure 3 The temperature change trend graphs are for both the example and comparative examples.

[0075] Explanation of reference numerals in the attached figures:

[0076] 1. Rare earth-based PET composite material layer; 2. Fluorine-containing layer; 3. Heat dissipation backplate; 4. Stainless steel frame; 5. Solar cell; 6. Thermal insulation foam board; 7. Patch thermocouple. Detailed Implementation

[0077] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0078] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0079] The PET resin used in the following embodiments of the present invention is of type JT-211.

[0080] The antioxidant used in the following embodiments of the present invention is antioxidant 1076.

[0081] Example 1: Heat dissipation backplate

[0082] like Figure 1 As shown, a high-efficiency heat dissipation backsheet for rare earth-based photovoltaic cells includes a rare earth-based PET composite material layer 1 and a fluorine-containing layer 2 coated on the surface of the rare earth-based PET composite material layer 1; wherein, the rare earth-based PET composite material includes, by mass parts: 62 parts of PET resin, 35 parts of functional PET masterbatch, and 3 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including NH2-PET resin, modified flake lanthanum cerium oxide, and dispersant.

[0083] The preparation method of the above-mentioned high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells includes the following steps:

[0084] 1. Preparation of NH2-PET resin

[0085] 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours until the water content is below 0.01%;

[0086] 2) Add 10g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100℃ to collect the distilled ethylene glycol.

[0087] 3) Weigh 36g of dried 2-aminoterephthalic acid, 15g of purified ethylene glycol and 17mg of antimony glycol and add them to a flask. Purge the system with nitrogen to replace the air.

[0088] 4) Insert a water separator and a stirring paddle into the mouth of the flask, and place it in an oil bath at a temperature of 250℃ and a stirring rate of 250r / min to carry out the esterification reaction.

[0089] 5) After the water separator has collected more than 6.9g of water, connect the system to the vacuum pump to slowly reduce the system pressure to 5kPa;

[0090] 6) Adjust the oil bath temperature to 270℃ and continue the reaction for 1.5 hours to carry out pre-polymerization;

[0091] 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 280°C. Continue the reaction for 2 hours to carry out the final polycondensation.

[0092] 8) After the reaction, nitrogen gas is used to break the vacuum and the melt is rapidly cooled with water to obtain NH2-PET resin.

[0093] 2. Preparation of modified plate-shaped lanthanum cerium oxide

[0094] I. Preparation of sheet-like lanthanum cerium oxide:

[0095] 1) Weigh cerium carbonate and lanthanum carbonate in a molar ratio of 18:1;

[0096] 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water, and prepare a 0.35 mol / L lanthanum nitrate and cerium nitrate solution;

[0097] 3) Dissolve a small amount of the surfactant sodium oleate in deionized water to prepare a 5 g / L surfactant solution;

[0098] 4) Dissolve ammonium oxalate in deionized water to prepare a 0.4 mol / L ammonium oxalate solution;

[0099] 5) Mix the lanthanum nitrate and cerium nitrate solution and the surfactant solution at a mass ratio of 1:1.8; pour the mixed solution into a flask, heat and stir at 60°C at a speed of 30 r / min; add ammonium oxalate solution until precipitation is complete, and continue the reaction for 2 h, then allow it to settle at room temperature for 12 h.

[0100] 6) The precipitate was filtered, washed and dried to obtain lanthanum cerium oxalate powder;

[0101] 7) Lanthanum oxalate was calcined at 750℃ for 3 hours to obtain flaky lanthanum oxalate powder with a particle size of 3 μm and a particle size range of 12-18 μm. 50 =15μm, the thickness of the sheet-like lanthanum cerium oxide is 250-400nm;

[0102] 8) Repeat the above steps, adjusting the stirring speed in step 5) to 60 r / min and 100 r / min respectively, to finally obtain plate-like lanthanum cerium oxide with particle sizes of 2 and 1, respectively, with diameters of 2-8 μm and D. 50 =5μm and 0.1-2μm, D 50 =1μm.

[0103] II. Modified flaky lanthanum and cerium oxide

[0104] 1) Add 10g of flake lanthanum cerium oxide, 50mL of deionized water, 280mL of ethanol and 15mL of ammonia to the flask, and stir until completely dispersed;

[0105] 2) Turn on the heating, and set the reaction temperature to 45℃;

[0106] 3) Measure 200 mL of ethanol and add 2 mL of silane coupling agent 3-isocyanate-propyltrimethoxysilane to prepare a homogeneous solution;

[0107] 4) After the temperature stabilizes, add the ethanol solution of silane coupling agent dropwise to the flask and continue the reaction for 10 hours;

[0108] 5) After the reaction, the system was allowed to stand and cool, and then centrifuged. It was washed with ethanol more than 5 times, placed in a vacuum oven, and vacuum dried at 50°C to obtain modified flaky lanthanum cerium oxide.

[0109] 3. Preparation of functional PET masterbatch

[0110] Modified flaky lanthanum oxide, NH2-PET resin, and dispersant DYD-9806 were weighed in a mass ratio of 36:52:12, wherein the ratio of the three particle sizes of the modified lanthanum oxide was particle size 1: particle size 2: particle size 3 = 1:1.5:1. The modified lanthanum oxide, NH2-PET resin, and dispersant DYD-9806 were mixed in a high-speed mixer to ensure uniform mixing and form a blend. The blend was then fed into a twin-screw extruder for melt extrusion and granulation to obtain functional PET masterbatch. The temperatures of each section of the twin-screw extruder were 240, 255, 255, 270, and 270℃, the die temperature was 270℃, and the feed rate was 300 g / min.

[0111] 4. Preparation of backplate

[0112] 1) PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast onto a cooling drum for rapid cooling to form a rare earth-based PET composite material layer with a thickness of 350μm;

[0113] 2) Polyvinylidene fluoride is coated on both sides of the rare earth-based PET composite material layer and microwave cured for 10 minutes to form a fluorine-containing layer with a thickness of 25 μm, thus obtaining a high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells.

[0114] Example 2: Heat dissipation backplate

[0115] like Figure 1As shown, a high-efficiency heat dissipation backsheet for rare earth-based photovoltaic cells includes a rare earth-based PET composite material layer 1 and a fluorine-containing layer 2 coated on the surface of the rare earth-based PET composite material layer 1; wherein, the rare earth-based PET composite material includes, by mass parts: 70 parts of PET resin, 28 parts of functional PET masterbatch, and 2 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including NH2-PET resin, modified flake lanthanum cerium oxide, and dispersant.

[0116] The preparation method of the above-mentioned high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells includes the following steps:

[0117] 1. Preparation of NH2-PET resin

[0118] 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours until the water content is below 0.01%;

[0119] 2) Add 8g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100℃ to collect the distilled ethylene glycol.

[0120] 3) Weigh 36g of dried 2-aminoterephthalic acid, 17g of purified ethylene glycol and 16mg of antimony glycol and add them to a flask. Purge the system with nitrogen to replace the air.

[0121] 4) Insert a water separator and a stirring paddle into the mouth of the flask, and place it in an oil bath at a temperature of 250°C and a stirring rate of 300 r / min to carry out the esterification reaction.

[0122] 5) After the water separator has collected more than 6.9g of water, connect the system to the vacuum pump to slowly reduce the system pressure to 5kPa;

[0123] 6) Adjust the oil bath temperature to 270 ℃ and continue the reaction for 1.5 h to carry out pre-condensation;

[0124] 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 280 °C. Continue the reaction for 2.5 h to carry out the final polycondensation.

[0125] 8) After the reaction, nitrogen gas is used to break the vacuum and the melt is rapidly cooled with water to obtain NH2-PET resin.

[0126] 2. Preparation of modified plate-shaped lanthanum cerium oxide

[0127] I. Preparation of sheet-like lanthanum cerium oxide:

[0128] 1) Weigh cerium carbonate and lanthanum carbonate in a molar ratio of 12:1;

[0129] 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water, and prepare a 0.65 mol / L lanthanum nitrate and cerium nitrate solution;

[0130] 3) Dissolve a small amount of surfactant polyallyl ammonium chloride in deionized water to prepare a surfactant solution of 6.5 g / L;

[0131] 4) Dissolve ammonium oxalate in deionized water to prepare a 0.65 mol / L ammonium oxalate solution;

[0132] 5) Mix the lanthanum nitrate and cerium nitrate solution and the surfactant solution at a mass ratio of 1:2.8; pour the mixed solution into a flask, heat and stir at 90°C at a speed of 30 r / min; add ammonium oxalate solution until precipitation is complete, and continue the reaction for 4 h, then allow it to settle at room temperature for 8 h.

[0133] 6) The precipitate was filtered, washed and dried to obtain lanthanum cerium oxalate powder;

[0134] 7) Lanthanum oxalate was calcined at 900℃ for 3 hours to obtain flaky lanthanum oxalate powder with a particle size of 3 μm and a particle size range of 12-18 μm. 50 =15μm, and the thickness of the sheet-like lanthanum cerium oxide is 150-400nm;

[0135] 8) Repeat the above steps, adjusting the stirring speed in step 5) to 60 r / min and 100 r / min respectively, to finally obtain plate-like lanthanum cerium oxide with particle sizes of 2 and 1, respectively, with diameters of 2-8 μm and D. 50 =5μm and 0.1-2μm, D 50 =1μm.

[0136] II. Modified flaky lanthanum and cerium oxide

[0137] 1) Add 10g of flake lanthanum cerium oxide, 70mL of deionized water, 350mL of ethanol and 20mL of ammonia to the flask, and stir until completely dispersed;

[0138] 2) Turn on the heating, and set the reaction temperature to 60℃;

[0139] 3) Measure 200 mL of ethanol and add 1.5 mL of silane coupling agent 3-isocyanopropyltriethoxysilane to prepare a homogeneous solution;

[0140] 4) After the temperature stabilizes, add an ethanol solution of silane coupling agent dropwise to the flask and continue the reaction for 8.5 hours;

[0141] 5) After the reaction, the system was allowed to stand and cool, then centrifuged and washed with ethanol more than 5 times. The system was then placed in a vacuum oven and dried under vacuum at 50°C to obtain modified flaky lanthanum cerium oxide.

[0142] 3. Preparation of functional PET masterbatch

[0143] Modified flaky lanthanum oxide, NH2-PET resin, and dispersant AC540A were weighed at a mass ratio of 33:57:10, wherein the ratio of the three particle sizes of the modified lanthanum oxide was particle size 1: particle size 2: particle size 3 = 1:1.5:1. The modified lanthanum oxide, NH2-PET resin, and dispersant AC540A were mixed in a high-speed mixer to ensure uniform mixing and form a blend. The blend was then fed into a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch. The temperatures of each section of the twin-screw extruder were 240, 255, 255, 270, and 270°C, the die temperature was 270°C, and the feed rate was 300 g / min.

[0144] 4. Preparation of backplate

[0145] 1) PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast onto a cooling drum for rapid cooling to form a rare earth-based PET composite material layer with a thickness of 300μm;

[0146] 2) Polyvinylidene fluoride is coated on both sides of the rare earth-based PET composite material layer and microwave cured for 20 minutes to form a fluorine-containing layer with a thickness of 40 μm, and finally a high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells is obtained.

[0147] Example 3: Heat dissipation backplate

[0148] like Figure 1 As shown, a high-efficiency heat dissipation backsheet for rare earth-based photovoltaic cells includes a rare earth-based PET composite material layer 1 and a fluorine-containing layer 2 coated on the surface of the rare earth-based PET composite material layer 1; wherein, the rare earth-based PET composite material includes, by mass parts: 80 parts of PET resin, 18 parts of functional PET masterbatch, and 2 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including NH2-PET resin, modified flake lanthanum cerium oxide, and dispersant.

[0149] The preparation method of the above-mentioned high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells includes the following steps:

[0150] 1. Preparation of NH2-PET resin

[0151] 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours until the water content is below 0.01%;

[0152] 2) Add 5g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100℃ to collect the distilled ethylene glycol.

[0153] 3) Weigh 36g of dried 2-aminoterephthalic acid, 19.84g of purified ethylene glycol and 15mg of antimony glycol and add them to a flask. Purge the system with nitrogen to replace the air.

[0154] 4) Insert a water separator and a stirring paddle into the mouth of the flask, and place it in an oil bath at a temperature of 250℃ and a stirring rate of 350r / min to carry out the esterification reaction.

[0155] 5) After the water separator has collected more than 6.9g of water, connect the system to the vacuum pump to slowly reduce the system pressure to 5kPa;

[0156] 6) Adjust the oil bath temperature to 270℃ and continue the reaction for 2 hours to carry out pre-condensation;

[0157] 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 290 °C. Continue the reaction for 3 hours to carry out the final polycondensation.

[0158] 8) After the reaction, nitrogen gas is used to break the vacuum and the melt is rapidly cooled with water to obtain NH2-PET resin.

[0159] 2. Preparation of modified plate-shaped lanthanum cerium oxide

[0160] I. Preparation of sheet-like lanthanum cerium oxide:

[0161] 1) Weigh cerium carbonate and lanthanum carbonate at a molar ratio of 45:1;

[0162] 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water, and prepare a 0.25 mol / L lanthanum nitrate and cerium nitrate solution;

[0163] 3) Dissolve a small amount of surfactant polyallyl ammonium chloride in deionized water to prepare a surfactant solution of 18 g / L;

[0164] 4) Dissolve ammonium oxalate in deionized water to prepare a 0.88 mol / L ammonium oxalate solution;

[0165] 5) Mix the lanthanum nitrate and cerium nitrate solution and the surfactant solution at a mass ratio of 1:2.6; pour the mixed solution into a flask, heat and stir at 60°C at a speed of 30 r / min; add ammonium oxalate solution until precipitation is complete, and continue the reaction for 4 h, then allow it to settle at room temperature for 20 h.

[0166] 6) The precipitate was filtered, washed and dried to obtain lanthanum cerium oxalate powder;

[0167] 7) Lanthanum oxalate was calcined at 1000℃ for 3 hours to obtain flaky lanthanum oxalate powder with a particle size of 3 μm and a particle size range of 12-18 μm. 50=15μm, the thickness of the sheet-like lanthanum cerium oxide is 250-400nm;

[0168] 8) Repeat the above steps, adjusting the stirring speed in step 5) to 60 r / min and 100 r / min respectively, to finally obtain plate-like lanthanum cerium oxide with particle sizes of 2 and 1, respectively, with diameters of 2-8 μm and D. 50 =5μm and 0.1-2μm, D 50 =1μm.

[0169] II. Modified flaky lanthanum and cerium oxide

[0170] 1) Add 10g of flake lanthanum cerium oxide, 80mL of deionized water, 400mL of ethanol and 25mL of ammonia to the flask, and stir until completely dispersed;

[0171] 2) Turn on the heating, and set the reaction temperature to 80℃;

[0172] 3) Measure 200 mL of ethanol and add 1 mL of silane coupling agent 3-isocyanate-propylmethyldimethoxysilane to prepare a homogeneous solution;

[0173] 4) After the temperature stabilizes, add the ethanol solution of silane coupling agent dropwise to the flask and continue the reaction for 6.5 hours;

[0174] 5) After the reaction, the system was allowed to stand and cool, then centrifuged and washed with ethanol more than 5 times. The system was then placed in a vacuum oven and dried under vacuum at 50°C to obtain modified flaky lanthanum cerium oxide.

[0175] 3. Preparation of functional PET masterbatch

[0176] Modified flaky lanthanum oxide, NH2-PET resin, and dispersant GLYCOLUBE P were weighed in a mass ratio of 40:48:12, wherein the ratio of the three particle sizes of the modified lanthanum oxide was particle size 1: particle size 2: particle size 3 = 1:1.5:1. The modified lanthanum oxide, NH2-PET resin, and dispersant GLYCOLUBE P were mixed in a high-speed mixer to ensure uniform mixing and form a blend. The blend was then fed into a twin-screw extruder for melt extrusion and granulation to obtain functional PET masterbatch. The temperatures of each section of the twin-screw extruder were 240, 255, 255, 270, and 270°C, the die temperature was 270°C, and the feed rate was 300 g / min.

[0177] 4. Preparation of backplate

[0178] 1) PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast onto a cooling drum for rapid cooling to form a rare earth-based PET composite material layer with a thickness of 200μm;

[0179] 2) Polyvinylidene fluoride is coated on both sides of the rare earth-based PET composite material layer and microwave cured for 18 minutes to form a fluorine-containing layer with a thickness of 40 μm, thus obtaining a high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells.

[0180] Comparative Example 1

[0181] The difference from Example 1 is that flaky lanthanum oxide is not used. Instead, commercially available lanthanum oxide is mixed with lanthanum oxide in a molar ratio of 36:1 (lanthanum-cerium atomic ratio of 18:1) as raw material. The mixed lanthanum oxide is then treated according to the particle size requirements of particle size 1, particle size 2, and particle size 3. The resulting three particle sizes are then mixed with lanthanum oxide of the three particle sizes according to the particle size ratio of Example 1. The lanthanum oxide is then modified using the same modification method as in Example 1, and all other aspects are the same as in Example 1.

[0182] Comparative Example 2

[0183] The difference from Example 1 is that only flaky lanthanum oxide is used, and the flaky lanthanum oxide is not modified; otherwise, it is the same as Example 1.

[0184] Comparative Example 3

[0185] The difference from Example 1 is that the NH2-PET resin used as the raw material for the functional PET masterbatch is replaced with ordinary PET resin, that is, the PET resin is not modified. Otherwise, it is the same as Example 1.

[0186] Comparative Example 4

[0187] The difference from Example 1 is that no surfactant is added in the step of preparing lanthanum cerium oxide (lanthanum cerium oxide has no flake morphology), otherwise it is the same as Example 1.

[0188] Comparative Example 5

[0189] The difference from Example 1 is that the modified flaky lanthanum cerium oxide consists of only one particle size, that is, modified flaky lanthanum cerium oxide with a particle size of 1 is used, and the rest is the same as in Example 1.

[0190] Comparative Example 6

[0191] The difference from Example 1 is that the modified flaky lanthanum cerium oxide consists of only one particle size, namely, modified flaky lanthanum cerium oxide with a particle size of 3. The rest is the same as in Example 1.

[0192] Comparative Example 7

[0193] The difference from Example 1 is that the ratio of the three particle sizes of the modified flaky lanthanum cerium oxide is particle size 1: particle size 2: particle size 3 = 1:1:1, and the rest is the same as in Example 1.

[0194] Using commercial PET backsheets as a control group, the heat dissipation performance of the heat dissipation backsheets obtained in the above embodiments and comparative examples was evaluated, using methods such as... Figure 2 The heat dissipation evaluation system shown includes a heat dissipation backplate 3, a stainless steel frame 4, solar cells 5, a thermal insulation foam board 6, and a patch thermocouple 7. The stainless steel frame 4 is tilted at 40°. The heat dissipation backplate 3 and solar cells 5 are placed on the stainless steel frame 4 from bottom to top. The outer periphery of the contact points between the heat dissipation backplate 3, solar cells 5, and stainless steel frame 4 is surrounded by the thermal insulation foam board 6 to prevent heat conduction between them and the stainless steel frame. A patch thermocouple 7 is attached to the upper surface of the solar cells 5 to record the temperature changes on the surface of the solar cells. This heat dissipation evaluation system was tested under simulated light source conditions, and also simulated the tilt angle of outdoor solar cells.

[0195] Table 1 shows the performance parameters of the heat dissipation backplates for the control group, each embodiment, and the comparative examples, as well as the corresponding solar cell output power. The specific heat dissipation effect of the solar cells is shown in [Table 1]. Figure 3 .

[0196] Table 1 Performance parameters of the heat dissipation backplate and corresponding solar cell output power

[0197]

[0198] Table 1 shows that the control group has the lowest thermal conductivity, reflectivity, and emissivity. When used as a battery backsheet, it results in the lowest battery output power, indicating the worst heat dissipation. This is consistent with... Figure 3 The highest surface temperature of the battery is consistent with that of the samples in Examples 1-3. The high thermal conductivity, reflectivity, and emissivity of these samples determine their excellent heat dissipation performance and ideal battery output power. Figure 3 The results showed a lower battery surface temperature. Comparative Examples 1 and 4 used mixed lanthanum-cerium oxide and synthesized non-flaky lanthanum-cerium oxide as fillers, respectively. Their thermal conductivity and reflectivity were significantly lower than in the examples, leading to varying degrees of reduced heat dissipation, i.e., a significant increase in battery surface temperature. Comparative Examples 2 and 3 used unmodified lanthanum-cerium oxide and unmodified PET as raw materials in the preparation of the backsheet, respectively. This resulted in reduced filler dispersibility, leading to a decrease in the thermal conductivity, reflectivity, and emissivity of the backsheet, and a certain increase in battery surface temperature. Comparative Examples 5 and 6 used single-size fillers, while Comparative Example 7 used multi-size fillers, but with varying particle size ratios. This mainly resulted in reduced reflectivity, and a slight increase in battery surface temperature compared to the examples.

[0199] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells, characterized in that: The product comprises a rare earth-based PET composite material layer and a fluorine-containing layer coated on the surface of the rare earth-based PET composite material layer; wherein, the rare earth-based PET composite material comprises, by mass parts: 60-80 parts of PET resin, 18-35 parts of functional PET masterbatch, and 2-3 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including modified flake lanthanum cerium oxide, NH2-PET resin and dispersant in a mass ratio of 30-40:46-60:8-14; The modified flaky lanthanum cerium oxide includes three particle sizes: 1: 0.1-2 μm, D: ... 50 =1μm, particle size 2: 2-8μm, D 50 =5μm, particle size 3: 12-18μm, D 50 =15μm; the ratio of the three particle sizes is particle size 1: particle size 2: particle size 3 = 1:1.5:1, and the thickness of the modified lanthanum cerium oxide plates with the three particle sizes is 20-400nm; NH2-PET resin is prepared by the following method: S11. Place 2-aminoterephthalic acid in a vacuum oven to dry; S12. Add 4A molecular sieve to ethylene glycol, soak overnight, and purify ethylene glycol; S13. Add 2-aminoterephthalic acid, purified ethylene glycol and antimony glycol to the flask, and purge the system with nitrogen to replace the air. S14. Insert a water separator and a stirring paddle into the mouth of the flask, and conduct an oil bath to carry out esterification, pre-condensation and final condensation reactions in sequence. S15. After the reaction, nitrogen gas is used to break the vacuum, and the melt is rapidly cooled with water to obtain NH2-PET resin. Modified flaky lanthanum cerium oxide was prepared by the following method: I. Preparation of sheet-like lanthanum cerium oxide: S21. Weigh out cerium carbonate and lanthanum carbonate in proportion, and dissolve lanthanum carbonate and cerium carbonate in nitric acid solution to obtain lanthanum cerium nitrate solution. S22. Mix the lanthanum nitrate and cerium nitrate solution and the surfactant solution in a certain proportion, and then add ammonium oxalate solution until precipitation is complete; S23. The precipitate is filtered, washed and dried to obtain lanthanum cerium oxalate powder; S24. Lanthanum oxalate was calcined at 600-1000℃ for 3 hours to obtain flaky lanthanum oxalate powder. II. Modified flaky lanthanum and cerium oxide: The prepared lanthanum cerium oxide sheets were modified using silane coupling agents.

2. The high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells according to claim 1, characterized in that: In S11, drying at 120-180℃ for 2-5 hours reduces the water content to below 0.01%. In S12, the soaked ethylene glycol is filtered, and after filtration, it is distilled under reduced pressure at 100°C to collect the distilled ethylene glycol. In S14, the esterification reaction temperature is 250℃ and the stirring rate is 200-350 r / min; After the water separator collects more than 6.9g of water, the system pressure is slowly reduced to 5kPa to carry out pre-condensation. The oil bath temperature is adjusted to 270℃ and the reaction lasts for 1.5-2 hours. Reduce the pressure to below 50 Pa to carry out final polycondensation, adjust the oil bath temperature to 280-290℃, and let the reaction continue for 2-3 hours.

3. The high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells according to claim 1, characterized in that: In step I, during the preparation of sheet-like lanthanum cerium oxide: In S21, the molar ratio of cerium carbonate to lanthanum carbonate is (90-9):1, and the concentration of the resulting lanthanum nitrate cerium solution is 0.2-0.8 mol / L. In S22, the surfactant is one or more of sodium oleate, polyallyl ammonium chloride, hexadecyltrimethylammonium bromide, and sodium dodecyl sulfate, and the concentration of the surfactant is 3-20 g / L. Lanthanum nitrate solution and surfactant solution are mixed at a mass ratio of 1:(1.6-2.8). After mixing, the lanthanum nitrate solution and surfactant solution are heated and stirred at 40-120℃ with a rotation speed of 30-100 r / min. By controlling the rotation speed, flake-shaped lanthanum nitrate solution of different particle sizes can be obtained. When the rotation speed is 20-40 r / min, a particle size of 3 is obtained; when the rotation speed is 50-70 r / min, a particle size of 2 is obtained; and when the rotation speed is 90-110 r / min, a particle size of 1 is obtained. The concentration of ammonium oxalate solution is 0.36-0.89 mol / L. After adding ammonium oxalate solution until precipitation is complete, continue the reaction for 2-5 hours, and then allow it to settle at room temperature for 8-24 hours.

4. The high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells according to claim 1, characterized in that: Step II, modifying plate-like lanthanum cerium oxide, includes the following steps: S31. Mix and stir the flake lanthanum cerium oxide, deionized water, ethanol and ammonia until completely dispersed, and then heat. S32. Mix ethanol and silane coupling agent to obtain silane coupling agent solution; S33. Add the silane coupling agent solution dropwise to the solution system obtained in step S31 and react. After the reaction, allow the system to stand and cool, centrifuge, wash, and dry.

5. The high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells according to claim 4, characterized in that: The silane coupling agent is one of 3-isocyanopropyltrimethoxysilane, 3-isocyanopropyltriethoxysilane, and 3-isocyanopropylmethyldimethoxysilane.

6. The high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells according to claim 1, characterized in that: The thickness of the rare earth-based PET composite layer is 200-400μm, the thickness of the fluorine-containing layer is 20-40μm, and the material of the fluorine-containing layer is polyvinylidene fluoride; The antioxidant is one or more of antioxidant 1076, antioxidant 3114, and antioxidant 245; The dispersant is one or more of DYD-9806, GLYCOLUBE P, and AC540A.

7. A method for preparing a high-efficiency heat dissipation backplate for rare-earth-based photovoltaic cells as described in any one of claims 1-6, characterized in that: The method includes the following steps: I. Preparation of Functional PET Masterbatch Modified flake lanthanum cerium oxide, NH2-PET resin, and dispersant are mixed in a high-speed mixer to ensure uniform mixing and form a blend. The blend is then added to a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch.

2. PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast onto a cooling drum for rapid cooling to form a rare earth-based PET composite material layer.

3. Apply polyvinylidene fluoride to both sides of the rare earth-based PET composite material layer and microwave cure for 10-20 minutes to form a fluorine-containing layer, thus obtaining a high-efficiency heat dissipation backplate for rare earth-based photovoltaic cells.

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