A composite flux material and its preparation method, and a photovoltaic module lamination welding process.

Abstract

This application belongs to the field of photovoltaic welding technology, specifically providing a composite flux material and its preparation method, as well as a photovoltaic module lamination welding process. The process includes the following steps: 1) Mixing L-tartaric acid, fatty amine, and xylene uniformly, then heating and reacting, filtering, and recrystallizing in deionized water to obtain a precursor material; 2) Dissolving terminal mercapto polyethylene glycol and cyclodextrin derivatives in deionized water, then adding maleimide and a buffer solution, reacting to obtain a conditioning solution; 3) Mixing the precursor material and conditioning solution uniformly, then adding an activator, solvent, film-forming agent, surfactant, pH adjuster, antioxidant, corrosion inhibitor, and rheology modifier, and mixing until uniform to obtain the final product. The composite flux material of this application has the advantages of improving the wettability of solder joints and enhancing welding performance.

Description

Technical Field

[0001] This application belongs to the field of photovoltaic welding technology, and in particular relates to a composite welding flux material and its preparation method, and a photovoltaic module lamination welding process. Background Technology

[0002] With the continuous progress and iteration of photovoltaic cell technology, several technical routes have been developed in cell welding technology. For example, in the topcon and HJT processes of OBB design, dispensing welding process, film coating welding process, and XBC cell back welding process can be used.

[0003] Among them, the dispensing welding process has problems such as unstable welding quality, high process difficulty, and low yield; the film coating welding process has problems such as unstable film pull-out force, high difficulty in front-end EL quality control, and low production yield; the XBC battery back welding process has high welding precision, but the battery is easy to bend after welding, and the finished module has a high fragmentation rate after lamination.

[0004] In response, to improve the welding quality of photovoltaic cells, technicians have carried out a series of research and development activities. For example, the patent document with application publication number CN112768544A discloses an IBC photovoltaic cell module and its welding process. By setting an insulating resin layer and a solder paste layer on the back of the cell, and connecting and connecting the solder paste layers together in series with copper foil strips, the interconnecting strips are replaced, reducing costs. At the same time, the good mechanical properties and heat resistance of the insulating resin layer are utilized to reduce the generation of microcracks in the IBC cell, thereby improving the performance of the photovoltaic module.

[0005] For example, patent application CN111112789A discloses a cell welding process for horizontally connected photovoltaic modules, including the following steps: Step 1: Determine the number of cells, check for defects such as missing corners or cracks, confirm the cells are intact, and then place one cell face up; Step 2: Pre-treatment of interconnect strips; Step 3: Place one cell in the middle of the heating plate, and lay a set of welding strips on the main grid line of the cell; Step 4: Perform single-cell welding; Step 5: Pre-treatment before string welding; Step 6: Perform string welding on the single-cell welded cells. This invention welds individual cells and then strings multiple groups of cells together, resulting in good welding quality. It avoids welding misalignment or unstable contact that can occur with direct string welding, thus improving welding quality. Immersing the interconnect strips in a properly formulated flux improves wettability during welding.

[0006] The flux materials used in the above welding process have limited effect on improving the wetting performance of the weld joints during welding, and cannot meet the performance requirements of high-performance photovoltaic modules. Therefore, how to improve the wetting performance during welding is a technical problem that urgently needs to be solved. Summary of the Invention

[0007] To address the aforementioned issues and further improve the wetting performance of weld joints during welding, this application provides a composite flux material, its preparation method, and a photovoltaic module lamination welding process.

[0008] This application first provides a method for preparing a composite flux material, including the following steps:

[0009] 1) Mix L-tartaric acid, fatty amine, and xylene evenly, then heat to react, filter, and recrystallize in deionized water to obtain the precursor.

[0010] 2) Dissolve terminal thiol polyethylene glycol and cyclodextrin derivative in deionized water, then add maleimide and buffer solution, and the reaction yields a conditioning solution;

[0011] 3) Take the precursor material and conditioning liquid, mix them evenly, and then continue to add the activator, solvent, film-forming agent, surfactant, pH adjuster, antioxidant, corrosion inhibitor and rheology modifier and continue to mix evenly to obtain the final product.

[0012] Furthermore, in step 1), the molar ratio of L-tartaric acid to fatty amine is 1:(1-1.2).

[0013] Furthermore, in step 1), the heating reaction is carried out at a temperature of 110-135°C for 1-3 hours.

[0014] Furthermore, in step 2), the mass ratio of terminal thiol polyethylene glycol to cyclodextrin derivative is (0.2-0.3):1.

[0015] Furthermore, in step 2), the cyclodextrin derivative is obtained by esterification polycondensation of cyclodextrin and citric acid.

[0016] Furthermore, in step 3), the activator is one or more of the following: methylsuccinic acid, DL-malic acid, lactic acid, oxalic acid, sebacic acid, azelaic acid, citric acid, salicylic acid, palmitic acid, adipic acid, benzoic acid, and stearic acid.

[0017] And / or, in step 3), the solvent is one or more of ethylene glycol monobutyl ether, propylene glycol methyl ether, n-octanol, tetrahydrofurfural, glycerol, diethylene glycol, and ethanol;

[0018] And / or, in step 3), the film-forming agent is a rosin-based film-forming agent;

[0019] And / or, in step 3), the surfactant is a nonionic surfactant;

[0020] And / or, in step 3), the antioxidant is a phenolic antioxidant;

[0021] And / or, in step 3), the corrosion inhibitor is benzotriazole;

[0022] And / or, in step 3), the rheology modifier is one or more of hydrogenated castor oil, ethyl cellulose, and polyamide wax.

[0023] This application provides a composite flux material, which is prepared using the above-described preparation method.

[0024] This application also provides a photovoltaic module lamination welding process, including the following steps:

[0025] S1: Install interconnecting strips on the welding machine;

[0026] S2: Apply composite flux material evenly to the surface of the welded patterned battery or the interconnect strip using a coating equipment, and use hot air for initial curing;

[0027] And / or, using a coating device, uniformly apply silver paste, solder paste, or composite flux to the surface of the battery or interconnect strip, and use hot air for preliminary curing; the battery is one of HJT / Topcon / BC battery, perovskite battery, or HJT\Topcon perovskite tandem battery;

[0028] The composite flux material is prepared using the above-described preparation method;

[0029] S3: After stacking the interconnecting strips and battery grid lines accordingly, pre-weld them together to form a string.

[0030] Furthermore, in step S1, the interconnecting strip is a SnPb-coated interconnecting strip or a SnPbBi-coated low-temperature interconnecting strip.

[0031] Compared with the prior art, this application has the following beneficial effects:

[0032] 1. This application uses organic acid as an activator and combines it with precursor liquid, conditioning liquid, film-forming agent, rheology modifier and other additives to form a stable adsorption film on the metal surface. This film plays a very good role in interface modification during welding, which refines the weld structure, improves the wettability of the weld joint, and thus improves the welding quality.

[0033] 2. The precursor of this application has a pyrrole ring and contains hydroxyl groups, which can form a stable adsorption on the metal surface. In addition, the cyclodextrin derivative in the conditioning solution can form a slip ring structure with terminal mercapto polyethylene glycol, and construct a dynamic network cross-linking system under the end-capping effect of maleimide, which improves the interfacial adsorption state of the precursor and other components, and reduces the IMC metal layer between the solder and the base metal during welding. Moreover, the precursor and conditioning solution can also form a trace carbon skeleton at high temperature as a physical barrier to inhibit the diffusion of base metal atoms from the base side to the solder joint side, further inhibiting the growth rate of IMC, and also improving the wettability of the solder joint on the base, thus obtaining a better welding effect. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the solder joint wetting performance of Example 2 and Control Group 1 of this application.

[0035] Figure 2 The images show SEM images of the weld joint cross-sections of Examples 1-2 and Control Groups 1-2 of this application. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0037] This application, based on extensive experimental research, provides a method for preparing a composite flux material, comprising the following steps:

[0038] 1) Mix L-tartaric acid, fatty amine, and xylene evenly, then heat to react, filter, and recrystallize in deionized water to obtain the precursor.

[0039] 2) Dissolve terminal thiol polyethylene glycol and cyclodextrin derivative in deionized water, then add maleimide and buffer solution, and the reaction yields a conditioning solution;

[0040] 3) Take the precursor material and conditioning liquid, mix them evenly, and then continue to add the activator, solvent, film-forming agent, surfactant, pH adjuster, antioxidant, corrosion inhibitor and rheology modifier and continue to mix evenly to obtain the final product.

[0041] Furthermore, in step 1), the molar ratio of L-tartaric acid to fatty amine is 1:(1-1.2).

[0042] In some specific embodiments, in step 1), the molar ratio of L-tartaric acid to fatty amine can be 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.14, 1:1.16, 1:1.18, or 1:2. More preferably, in step 1), a molar ratio of L-tartaric acid to fatty amine of 1:1.1 yields better experimental results.

[0043] In some specific embodiments, in step 1), the fatty amine can be one of propylamine, n-butylamine, dodecylamine, or octadecylamine. More preferably, in general, when the fatty amine in step 1) is n-butylamine, better technical effects can be obtained.

[0044] Furthermore, in step 1), the heating reaction is carried out at a temperature of 110-135°C for 1-3 hours.

[0045] In some specific embodiments, in step 1), the heating reaction can be carried out at temperatures of 110°C, 115°C, 120°C, 125°C, 130°C, and 135°C for 1 h, 1.5 h, 2 h, 2.5 h, and 3 h, respectively. More preferably, under normal circumstances, in step 1), the heating reaction at 120°C for 2 h yields better experimental results.

[0046] Furthermore, in step 2), the mass ratio of terminal thiol polyethylene glycol to cyclodextrin derivative is (0.2-0.3):1.

[0047] In some specific embodiments, in step 2), the mass ratio of terminal thiol polyethylene glycol to cyclodextrin derivative can be 0.2:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1, 0.25:1, 0.26:1, 0.27:1, 0.28:1, 0.29:1, or 0.3:1. More preferably, under normal circumstances, a mass ratio of terminal thiol polyethylene glycol to cyclodextrin derivative of 0.2:1 in step 2) yields better results.

[0048] Furthermore, in step 2), the cyclodextrin derivative is obtained by esterification polycondensation of cyclodextrin and citric acid.

[0049] Furthermore, in step 3), the activator is one or more of the following: methylsuccinic acid, DL-malic acid, lactic acid, oxalic acid, sebacic acid, azelaic acid, citric acid, salicylic acid, palmitic acid, adipic acid, benzoic acid, and stearic acid.

[0050] In some specific embodiments, under normal circumstances, when the organic acid in step 3) is composed of DL-malic acid and salicylic acid, better experimental results can be obtained. More preferably, in step 3), the organic acid is composed of DL-malic acid and salicylic acid in a mass ratio of 5:3.

[0051] And / or, in step 3), the solvent is one or more of ethylene glycol monobutyl ether, propylene glycol methyl ether, n-octanol, tetrahydrofurfural, glycerol, diethylene glycol, and ethanol;

[0052] In some specific embodiments, in step 3), the solvent is better when ethylene glycol monobutyl ether, propylene glycol methyl ether, n-octanol, or tetrahydrofurfural is used. More preferably, under normal circumstances, the experimental results are better when the solvent is ethylene glycol monobutyl ether, propylene glycol methyl ether, n-octanol, and tetrahydrofurfural in a mass ratio of 1:2:3:3.

[0053] And / or, in step 3), the film-forming agent is a rosin-based film-forming agent;

[0054] In some specific embodiments, more preferably, in step 1), the film-forming agent is rosin.

[0055] And / or, in step 3), the surfactant is a nonionic surfactant;

[0056] In some specific embodiments, more preferably, when octylphenol polyoxyethylene ether is selected as the surfactant in step 1), the effect is better.

[0057] And / or, in step 3), the antioxidant is a phenolic antioxidant;

[0058] In some specific embodiments, more preferably, hydroquinone is used as the antioxidant in step 1) to obtain better experimental results.

[0059] And / or, in step 3), the corrosion inhibitor is benzotriazole;

[0060] And / or, in step 3), the rheology modifier is one or more of hydrogenated castor oil, ethyl cellulose, and polyamide wax.

[0061] This application provides a composite flux material, which is prepared using the above-described preparation method.

[0062] This application also provides a photovoltaic module lamination welding process, including the following steps:

[0063] S1: Install interconnecting strips on the welding machine;

[0064] S2: Apply composite flux material evenly to the surface of the welded patterned battery or the interconnect strip using a coating equipment, and use hot air for initial curing;

[0065] And / or, using a coating device, uniformly apply silver paste, solder paste, or composite flux to the surface of the battery or interconnect strip, and use hot air for preliminary curing; the battery is one of HJT / Topcon / BC battery, perovskite battery, or HJT\Topcon perovskite tandem battery;

[0066] The composite flux material is prepared using the above-described preparation method;

[0067] S3: After stacking the interconnecting strips and battery grid lines accordingly, pre-weld them together to form a string.

[0068] Furthermore, in step S1, the interconnecting strip is a SnPb-coated interconnecting strip or a SnPbBi-coated low-temperature interconnecting strip.

[0069] Under normal circumstances, when SnPbBi coated low-temperature interconnecting strips are selected for the interconnecting strips in step S1, better technical results can be obtained.

[0070] Preferably, the photovoltaic module welding process of this application is applicable to the welding of OBBtopcon / HJT cells and XBC / perovskite cells.

[0071] Example 1

[0072] The preparation method of the composite flux material in this embodiment includes the following steps:

[0073] 1) Add 15 mL of xylene, 0.6 g of L-tartaric acid, and 0.322 g of n-butylamine to a 500 mL three-necked flask equipped with a stirrer, thermometer, and dropping funnel. Mix well and react at 120 °C for 2 h under stirring. Then cool to room temperature and filter. The product is recrystallized in deionized water to obtain the precursor.

[0074] 2) Add 2g of mercapto-terminated polyethylene glycol and 10g of sulfobutyl-β-cyclodextrin dissolved in deionized water to a three-necked flask, then add 0.5g of maleimide and 10mL of PBS buffer solution. After the reaction, the conditioning solution is obtained.

[0075] 3) Take 0.35g of precursor material and 5mL of conditioning solution and mix them evenly. Then add 8g of activator (composed of 5g DL-malic acid and 3g salicylic acid), 45g of solvent (composed of 5g ethylene glycol monobutyl ether, 10g propylene glycol methyl ether, 15g tetrahydrofurfuryl alcohol and 15g n-octanol), 30g of film-forming agent (ice white rosin), 1g of surfactant (octylphenol polyoxyethylene ether-10), pH adjuster, 1g of antioxidant (hydroquinone), 1g of corrosion inhibitor (benzotriazole), and 5g of rheology modifier (hydrogenated castor oil) and mix evenly to obtain the final product.

[0076] The photovoltaic module welding process in this embodiment includes the following steps:

[0077] S1: Install SnPbBi coated low-temperature interconnect strips on the welding machine;

[0078] S2: Apply composite flux material evenly to the surface of the battery or interconnect strip using a coating device, and use hot air for initial curing; the battery is one of HJT / Topcon / BC battery, perovskite battery, or HJT\Topcon perovskite tandem battery.

[0079] S3: After stacking the interconnecting strips and battery grid lines accordingly, they are connected in series by lamination and vacuum thermal welding. The lamination temperature is 150℃ and the lamination time is 20min.

[0080] Example 2

[0081] The preparation method of the composite flux material in this embodiment includes the following steps:

[0082] 1) Add 15 mL of xylene, 0.6 g of L-tartaric acid, and 0.322 g of n-butylamine to a 500 mL three-necked flask equipped with a stirrer, thermometer, and dropping funnel. Mix well and react at 120 °C for 2 h under stirring. Then cool to room temperature and filter. The product is recrystallized in deionized water to obtain the precursor.

[0083] 2) Add 2g of mercapto-terminated polyethylene glycol and 10g of cyclodextrin derivative dissolved in deionized water to a three-necked flask, then add 0.5g of maleimide and 10mL of PBS buffer solution. After the reaction, the conditioning solution is obtained.

[0084] 3) Take 0.35g of precursor material and 5mL of conditioning solution and mix them evenly. Then add 8g of activator (composed of 5g DL-malic acid and 3g salicylic acid), 45g of solvent (composed of 5g ethylene glycol monobutyl ether, 10g propylene glycol methyl ether, 15g tetrahydrofurfuryl alcohol and 15g n-octanol), 30g of film-forming agent (ice white rosin), 1g of surfactant (octylphenol polyoxyethylene ether-10), pH adjuster, 1g of antioxidant (hydroquinone), 1g of corrosion inhibitor (benzotriazole), and 5g of rheology modifier (hydrogenated castor oil) and mix evenly to obtain the final product.

[0085] The cyclodextrin derivative of this embodiment was prepared by the following steps: 5g of β-cyclodextrin, 2g of citric acid, and 50mL of deionized water were accurately weighed and added to a 250mL round-bottom flask and mixed evenly. Then, 1g of potassium dihydrogen phosphate was added and mixed evenly. The mixture was then heated to 100°C in an oil bath to completely dissolve all the components and obtain a reaction solution. The reaction solution was then transferred to a hot air drying oven and stirred at 140°C for 4 hours. The solution was then removed, washed with deionized water, and dried to obtain the final product.

[0086] The photovoltaic module welding process in this embodiment includes the following steps:

[0087] S1: Install SnPbBi coated low-temperature interconnect strips on the welding machine;

[0088] S2: Apply composite flux material evenly to the surface of the battery or interconnect strip using a coating device, and use hot air for initial curing; the battery is one of HJT / Topcon / BC battery, perovskite battery, or HJT\Topcon perovskite tandem battery.

[0089] S3: After stacking the interconnecting strips and battery grid lines accordingly, they are laminated and vacuum thermally welded together to form a string. The lamination temperature is 160℃ and the lamination time is 16min.

[0090] Control group 1

[0091] The preparation method of the flux material in this control group includes the following steps: Take 8g of activator (composed of 5g DL-malic acid and 3g salicylic acid), 45g of solvent (composed of 5g ethylene glycol monobutyl ether, 10g propylene glycol methyl ether, 15g tetrahydrofurfuryl alcohol and 15g n-octanol), 30g of film-forming agent (ice white rosin), 1g of surfactant (octylphenol polyoxyethylene ether-10), pH adjuster, 1g of antioxidant (hydroquinone), 1g of corrosion inhibitor (benzotriazole), and 5g of rheology modifier (hydrogenated castor oil) and mix them evenly.

[0092] The photovoltaic module welding process in this control group includes the following steps:

[0093] S1: Install SnPbBi coated low-temperature interconnect strips on the welding machine;

[0094] S2: Apply flux material evenly to the surface of the battery or interconnect strip using a coating device, and use hot air for initial curing; the battery is one of HJT / Topcon / BC battery, perovskite battery, or HJT\Topcon perovskite tandem battery.

[0095] S3: After stacking the interconnecting strips and battery grid lines accordingly, they are connected in series by lamination and vacuum thermal welding. The lamination temperature is 150℃ and the lamination time is 20min.

[0096] Control group 2

[0097] The preparation method of the composite flux material in this control group includes the following steps:

[0098] 1) Add 15 mL of xylene, 0.6 g of L-tartaric acid, and 0.322 g of n-butylamine to a 500 mL three-necked flask equipped with a stirrer, thermometer, and dropping funnel. Mix well and react at 120 °C for 2 h under stirring. Then cool to room temperature and filter. The product is recrystallized in deionized water to obtain the precursor.

[0099] 2) Take 0.35g of precursor material, 8g of activator (composed of 5g DL-malic acid and 3g salicylic acid), 45g of solvent (composed of 5g ethylene glycol monobutyl ether, 10g propylene glycol methyl ether, 15g tetrahydrofurfuryl alcohol and 15g n-octanol), 30g of film-forming agent (ice white rosin), 1g of surfactant (octylphenol polyoxyethylene ether-10), pH adjuster, 1g of antioxidant (hydroquinone), 1g of corrosion inhibitor (benzotriazole), and 5g of rheology modifier (hydrogenated castor oil) and mix them evenly to obtain the final product.

[0100] The photovoltaic module welding process in this control group includes the following steps:

[0101] S1: Install SnPbBi coated low-temperature interconnect strips on the welding machine;

[0102] S2: Apply flux material evenly to the surface of the battery or interconnect strip using a coating device, and use hot air for initial curing; the battery is one of HJT / Topcon / BC battery, perovskite battery, or HJT\Topcon perovskite tandem battery.

[0103] S3: After stacking the interconnecting strips and battery grid lines accordingly, they are connected in series by lamination and vacuum thermal welding. The lamination temperature is 150℃ and the lamination time is 20min.

[0104] Performance testing

[0105] 1. The flux materials from Example 2 and Control Group 1 were used to conduct welding performance tests according to GB / T9491-2021 standard. The results are as follows: Figure 1 As shown, the flux material of this application can effectively improve the wetting performance of the solder joint.

[0106] 2. The cross-sectional morphology of the weld joints obtained from the flux materials in Examples 1-2 and Control Groups 1-2 was observed using scanning electron microscopy. The results are as follows: Figure 2 As shown, this effectively improves the welding quality of the solder joints and reduces interface defects and the thickness of the IMC layer.

[0107] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this invention.

Claims

1. A method for preparing a composite flux material, characterized in that: Includes the following steps: 1) Mix 0.6g L-tartaric acid, 0.322g n-butylamine and 15mL xylene evenly, then heat to react, filter and recrystallize in deionized water to obtain the precursor. 2) Dissolve 2g of terminal thiol polyethylene glycol and 10g of cyclodextrin derivative in deionized water, then add 0.5g of maleimide and 10mL of PBS buffer solution, and the reaction yields the conditioning solution; 3) Take 0.35g of precursor material and 5mL of conditioning solution and mix them evenly. Then add 8g of activator, 45g of solvent, 30g of film-forming agent, 1g of surfactant, pH adjuster, 1g of antioxidant, 1g of corrosion inhibitor and 5g of rheology modifier and mix evenly to obtain the final product.

2. The method for preparing the composite flux material according to claim 1, characterized in that: In step 1), the heating reaction is carried out at a temperature of 110-135℃ for 1-3 hours.

3. The method for preparing the composite flux material according to claim 1, characterized in that: In step 2), the cyclodextrin derivative is obtained by esterification and polycondensation of cyclodextrin and citric acid.

4. The method for preparing the composite flux material according to claim 1, characterized in that: In step 3), the activator is one or more of the following: methylsuccinic acid, DL-malic acid, lactic acid, oxalic acid, sebacic acid, azelaic acid, citric acid, salicylic acid, palmitic acid, adipic acid, benzoic acid, and stearic acid. And / or, in step 3), the solvent is one or more of ethylene glycol monobutyl ether, propylene glycol methyl ether, n-octanol, tetrahydrofurfural, glycerol, diethylene glycol, and ethanol; And / or, in step 3), the film-forming agent is a rosin-based film-forming agent; And / or, in step 3), the surfactant is a nonionic surfactant; And / or, in step 3), the antioxidant is a phenolic antioxidant; And / or, in step 3), the corrosion inhibitor is benzotriazole; And / or, in step 3), the rheology modifier is one or more of hydrogenated castor oil, ethyl cellulose, and polyamide wax.

5. A composite flux material, characterized in that: It is prepared by any one of the preparation methods described in claims 1-4.

6. A photovoltaic module lamination welding process, characterized in that: Includes the following steps: S1: Install interconnecting strips on the welding machine; S2: Apply composite flux material evenly to the surface of the battery or interconnect strip using a coating device, and perform preliminary curing using hot air; the battery is one of HJT / TOPCon / BC battery, perovskite battery, or HJT / TOPCon perovskite tandem battery. The composite flux material is prepared by any one of the preparation methods described in claims 1-4; S3: After stacking the interconnecting strips and battery grid lines accordingly, they are laminated and vacuum thermally welded together to form a string.

7. The photovoltaic module lamination welding process according to claim 6, characterized in that: In step S1, the interconnecting strip is a SnPb-coated interconnecting strip or a SnPbBi-coated low-temperature interconnecting strip.

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