A conductive integrated encapsulation material for BC batteries, its preparation method, and a photovoltaic module.

Abstract

This invention relates to the field of photovoltaic technology, disclosing a conductive integrated encapsulation material for BC (Browser-Based Cell) batteries, its preparation method, and a photovoltaic module. The conductive integrated encapsulation material includes a transparent polymer base layer, an etched conductive structure, an insulating encapsulation layer, and connection channels. A first acid-absorbing coating is provided on the upper surface of the transparent polymer base layer. The etched conductive structure includes patterned grooves etched on the upper surface of the first acid-absorbing coating and the transparent polymer base layer, and conductive material filling the patterned grooves. The patterned grooves correspond to the circuit pattern on the back of the BC battery. The insulating encapsulation layer is disposed on the upper surface of the etched conductive structure and the first acid-absorbing coating. The connection channels include a plurality of spaced windows penetrating the insulating encapsulation layer and conductive adhesive filling the windows and electrically contacting the etched conductive structure. The conductive adhesive in each window corresponds to an electrode contact position of the BC battery. This conductive integrated encapsulation material simplifies the interconnection process of BC photovoltaic modules, reduces costs, and improves module reliability.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, specifically to a conductive integrated encapsulation material for BC batteries, its preparation method, and a photovoltaic module. Background Technology

[0002] Back-contact (BC) cells have become one of the important development directions of photovoltaic technology due to their advantages such as no grid lines (electrodes) on the front, aesthetics, and high efficiency. However, since all the electrodes of BC cells are located on the back, when they are used in photovoltaic modules, complex interconnection processes are required to connect the back electric fields (corresponding to the positive electrode) and emitters (corresponding to the negative electrode) of multiple cells to form a cell string.

[0003] Current methods primarily rely on a large number of solder ribbons and complex welding processes to address this issue. The mainstream BC photovoltaic module encapsulation process typically involves the following steps: applying insulating adhesive between the positive and negative electrodes of the BC cell (or omitting the adhesive printing step and using the composite solder ribbon structure for BC cell interconnection with a double-layer insulation layer as described in CN121586301A); then, to improve the contact between the solder ribbons and the cells and enhance the welding quality between the solder ribbons and the back electrodes of the cells, solder paste is applied; a large number of solder ribbons are placed and positioned, and heated to bring the ribbons into contact with the corresponding electrodes on the back of the cells for welding, thus connecting multiple cells to form a cell string; subsequently, a photovoltaic encapsulation film is laid; finally, a photovoltaic backsheet is covered, and then laminated to form a photovoltaic module.

[0004] However, the BC photovoltaic module encapsulation process has the following significant drawbacks: (1) High cost: It requires a large amount of expensive solder strips (usually tin-plated copper strips). (2) Complex process: The solder strip positioning accuracy is extremely high, the welding process window is narrow, and problems such as poor soldering and over-soldering are easy to occur. (3) Reliability risk: On the one hand, the heterogeneous interface between the solder strip and the cell is prone to fatigue under thermal stress, and there may be stress concentration at the solder joint, which can easily lead to hidden cracks and fragments of the cell. On the other hand, during the operation of the photovoltaic module, a large amount of heat is easily accumulated inside, resulting in excessively high internal operating temperature, which affects the stable and reliable output of its power generation; moreover, the encapsulation film (such as EVA encapsulation film) is prone to decomposition in a humid and hot environment to produce acetic acid and other substances that corrode the solder strip, electrodes, etc., resulting in poor resistance to humid and hot aging of the photovoltaic module, and after humid and hot aging, it is easy to have a large power decay, which reduces its reliability. (4) Increased weight of photovoltaic module: A large amount of solder strips increases the overall weight of the photovoltaic module, which is not conducive to the lightweight development of large-size photovoltaic modules. Therefore, there is an urgent need to develop a conductive integrated encapsulation material for BC cells that can simplify interconnection processes, reduce material costs, improve the reliability of BC photovoltaic modules, and achieve lightweight BC photovoltaic modules. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a conductive integrated encapsulation material for BC batteries, its preparation method, and a photovoltaic module.

[0006] Based on this, the present invention discloses a conductive integrated encapsulation material for BC batteries, including a transparent polymer base layer, an acid-absorbing coating, an etched conductive structure, an insulating encapsulation layer, and a connection channel. The acid-absorbing coating includes a first acid-absorbing coating disposed on the upper surface of a transparent polymer base layer; the etched conductive structure includes patterned grooves formed by local etching on the upper surfaces of the first acid-absorbing coating and the transparent polymer base layer and conductive material filled in the patterned grooves. The patterned grooves correspond to the circuit pattern on the back of the BC battery, so that the conductive material filled in the patterned grooves forms an embedded conductive circuit. The insulating encapsulation layer is disposed on the upper surface of the etched conductive structure and the first acid-absorbing coating; The connection channel includes several windows spaced apart from each other that run through the upper and lower surfaces of the insulating encapsulation layer and conductive adhesive that fills the windows and electrically contacts the etched conductive structure. The conductive adhesive in each window corresponds to an electrode contact position on the back of the BC battery.

[0007] Preferably, the patterned grooves have an etching depth of 100-500 nanometers and a width of 50-200 micrometers; The conductive material is a low resistivity conductive material with a resistivity ≤5μΩ·cm, which can be selected from nanowires or cured conductive silver paste.

[0008] Preferably, the acid-absorbing coating further includes a second acid-absorbing coating disposed on the lower surface of the transparent polymer base layer; the first and second acid-absorbing coatings are acrylic coatings with a thickness of 1-3 micrometers; the acrylic coating used to form the acrylic coating includes acrylic resin, acid-absorbing filler and thermally conductive-radiative heat dissipation filler mixed in a weight ratio of 50-60:1.3-2:1.5-3. The acrylic resin is a low-acid acrylic resin with an acid value ≤ 5 mg KOH / g; the acid-absorbing filler is at least one of calcium carbonate and magnesium hydroxide; the thermally conductive-radiative heat dissipation filler is at least one of boron nitride, aluminum nitride, silicon nitride, carbon nanotubes, and carbon fibers.

[0009] More preferably, the acrylic coating further includes additives mixed in a weight ratio of 50-60:28-54; the additives include one or more of curing agents, leveling agents, ultraviolet absorbers, defoamers, and solvents.

[0010] Preferably, the insulating encapsulation layer is at least one of cross-linked polyolefin film, ethylene-vinyl acetate copolymer film, multifunctional acrylic adhesive layer, and epoxy coating; the thickness of the insulating encapsulation layer is 3-10 micrometers.

[0011] Preferably, the conductive adhesive is anisotropic conductive adhesive or isotropic conductive adhesive; The transparent polymer base layer is a polyethylene terephthalate film or a polyimide film with a thickness of 10-20 micrometers.

[0012] This invention also discloses a method for preparing a conductive integrated encapsulation material for BC batteries, comprising the following steps: S1. Prepare the transparent polymer base layer; S2. Prepare a first acid-absorbing coating on the upper surface of a transparent polymer base layer; S3. Based on the circuit pattern on the back of the BC battery, the upper surface of the first acid-absorbing coating and the transparent polymer base layer is etched to form patterned grooves. S4. Fill the patterned grooves with conductive material to obtain an etched conductive structure with embedded conductive lines; S5. An insulating encapsulation layer is formed on the upper surface of the etched conductive structure and the first acid-absorbing coating. S6. Based on the electrode contact position on the back of the BC battery, selectively open windows in the insulating encapsulation layer to form windows for locally exposing embedded conductive lines with etched conductive structures. S7. Fill the window with conductive adhesive.

[0013] Preferably, step S2 further includes: preparing a second acid-absorbing coating on the lower surface of the transparent polymer base layer.

[0014] Preferably, in step S3, ultraviolet laser engraving or chemical etching is used to etch the upper surface of the first acid-absorbing coating and the transparent polymer base layer to form the patterned grooves.

[0015] Preferably, in step S4, conductive silver paste is filled into the patterned grooves using screen printing, scraping, or inkjet printing processes, and then cured at 100-200°C to form the conductive material.

[0016] Preferably, in step S5, the insulating encapsulation layer is formed by coating liquid insulating encapsulation material using a coating process and then pre-curing it, or by laminating solid insulating encapsulation film using a lamination process.

[0017] Preferably, in step S6, a visually-guided laser ablation process is used to selectively open windows to form the window.

[0018] The present invention also discloses a photovoltaic module, comprising a photovoltaic backsheet, a back sealing film, a conductive integrated sealing material, a BC cell, a front sealing film, and a photovoltaic front panel stacked from bottom to top; The conductive integrated encapsulation material is the conductive integrated encapsulation material for BC batteries described above in this invention, and the conductive adhesive connecting the channel faces the electrode on the back of the BC battery.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: The conductive integrated encapsulation material for BC batteries of the present invention integrates an insulating encapsulation layer, an etched conductive structure for conductive interconnection, and a precise connection channel into one unit. It can directly replace the insulating adhesive, solder paste, and solder strip in the existing soldering process, and achieve a precise, low-resistance, and reliable connection of the back electrode of the BC battery, thereby significantly reducing the cost and process complexity of BC battery photovoltaic modules.

[0020] (1) Significantly reduced cost: The conductive material (preferably nanowires or cured conductive silver paste) in the etched conductive structure and the conductive adhesive in the connection channel of the conductive integrated packaging material replace the expensive solder ribbon, and the material utilization rate is high, resulting in a significant reduction in the overall cost of the packaging material (the cost of the conductive integrated packaging material is reduced by 10-20%).

[0021] (2) Simplified packaging process: Photovoltaic module manufacturers only need to use the conductive integrated packaging material for BC cells of the present invention as a "ready-to-use" back packaging material, and perform conventional lamination with BC cells and photovoltaic backsheets to complete the interconnection, eliminating the cumbersome solder strip laying, positioning and welding steps, and improving production efficiency and yield.

[0022] (3) Improved connection accuracy and reliability: By pre-patterning and precisely grooving on the transparent polymer substrate, the conductive lines of the etched conductive structure are aligned at the micron level with the electrode circuit on the back of the BC battery, resulting in more precise contact. The conductive adhesive connection of the connection channel has better stress buffering capacity, reducing the risk of thermomechanical fatigue. In addition, acid-absorbing coatings (such as the first acid-absorbing coating and the second acid-absorbing coating) are combined. Through the synergistic effect of the low-acid acrylic resin, acid-absorbing filler, and thermally conductive-radiative heat dissipation filler in the acid-absorbing coating, it is ensured that the photovoltaic module using the conductive integrated encapsulation material for BC batteries can effectively reduce its operating temperature and its power decay rate after damp heat aging (DH2000h), thus greatly improving the long-term reliability of the BC battery photovoltaic module.

[0023] (4) Module thinning: such as 10-20 micrometer transparent polymer base layer and embedded planar conductive lines with etched conductive structure, which are thinner and lighter than the existing solder strip welding solution, which helps to realize the thinning of BC cell photovoltaic modules.

[0024] (5) Flexible design: The conductive circuit pattern of the etched conductive structure can be flexibly customized according to different BC battery models. It is applicable to various back contact batteries such as IBC, HBC, and JBC, and has strong versatility. Attached Figure Description

[0025] Figure 1 This is a schematic cross-sectional view of a conductive integrated encapsulation material for BC batteries according to this embodiment.

[0026] Figure 2 This is a top view of the conductive integrated encapsulation material for BC batteries in this embodiment after the insulating encapsulation layer has been removed.

[0027] Reference numerals: 1. Connection channel; 11. Window; 12. Conductive adhesive; 2. Insulating encapsulation layer; 3. First acid-absorbing coating; 4. Etched conductive structure; 41. Patterned groove; 42. Conductive material; 5. Transparent polymer base layer; 6. Second acid-absorbing coating. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] A conductive integrated encapsulation material for BC batteries according to the present invention, see [link to relevant documentation]. Figure 1-2 It has a multi-layer composite structure, which includes a transparent polymer base layer 5, an etched conductive structure 4, an insulating encapsulation layer 2, and a precise connection channel 1.

[0030] Among them, the transparent polymer base layer 5 is a polyethylene terephthalate (PET) film or a polyimide (PI) film with a thickness of 10-20 micrometers, which has good insulation, mechanical strength, thermal stability and dimensional stability.

[0031] The present invention provides a conductive integrated encapsulation material for BC batteries, which further includes a highly efficient acid-absorbing coating. Preferably, both the upper and lower surfaces of the transparent polymer base layer 5 are coated with an acid-absorbing coating (referred to as the first acid-absorbing coating 3 and the second acid-absorbing coating 6, respectively), which can effectively absorb acetic acid generated during long-term storage of the encapsulation film, ensuring the long-term reliability of the photovoltaic module.

[0032] Specifically, preferably, both the first acid-absorbing coating 3 and the second acid-absorbing coating 6 are acrylic coatings with a thickness of 1-3 micrometers, and the acrylic coatings are made of acrylic paint. The acrylic resin selected for the acrylic paint is a low-acid acrylic resin with an acid value ≤5mg KOH / g; during the preparation of the acrylic paint, the acid-absorbing filler added is precisely controlled to efficiently absorb the acetic acid generated during the long-term process of the encapsulation film; and thermally conductive-radiative heat dissipation filler is added in conjunction to efficiently radiate the heat generated during the operation of the photovoltaic module to the outside, thereby reducing the operating temperature of the photovoltaic module.

[0033] Specifically, the weight ratio of low-acid acrylic resin, acid-absorbing filler, and thermally conductive-radiative heat dissipation filler is 50-60:1.3-2:1.5-3. The acid-absorbing filler is preferably at least one of calcium carbonate and magnesium hydroxide. The thermally conductive-radiative heat dissipation filler is preferably at least one of boron nitride (BN), aluminum nitride (AlN), silicon nitride (Si3N4), carbon nanotubes, and carbon fibers. The main function of the thermally conductive-radiative heat dissipation filler is to conduct and radiate the heat generated during the operation of the photovoltaic module, further reducing the operating temperature of the photovoltaic module and preventing risks caused by excessive temperature. The purpose of the acid-absorbing filler is to absorb acidic substances generated during the hydrolysis of the encapsulant film, preventing acidic substances from radiating into the photovoltaic module and further improving the service life of the photovoltaic module. Through the synergistic combination of low-acid acrylic resin, acid-absorbing filler, and thermally conductive-radiative heat dissipation filler, it is ensured that the photovoltaic module using the conductive integrated encapsulation material for BC cells can effectively reduce its operating temperature and its power degradation rate after damp heat aging (DH2000h), thus greatly improving the long-term reliability of the BC cell photovoltaic module. In addition, acrylic coatings also include additives mixed in a weight ratio of 50-60:28-54; said additives include one or more of curing agents, leveling agents, ultraviolet light absorbers, defoamers, and solvents.

[0034] The etched conductive structure 4 is located on one surface (such as the upper surface) of the transparent polymer base layer 5, and includes a patterned groove 41 formed locally on the upper surface of the first acid-absorbing coating 3 and the transparent polymer base layer 5 according to the circuit pattern on the back of the BC battery, and a low-resistivity conductive material 42 filled in the patterned groove 41.

[0035] Specifically, the patterned grooves 41 can be formed on a local area of ​​the upper surface of the first acid-absorbing coating 3 and the transparent polymer base layer 5 by laser or chemical etching according to the circuit pattern on the back of the BC battery. Patterned grooves 41 are formed at both the positive and negative electrode positions on the back of the BC battery, with the patterned grooves 41 at the positive electrode and negative electrode positions spaced apart. Furthermore, the conductive material 42 filled in the patterned grooves 41 at the positive electrode position can connect the positive electrodes of the BC battery to each other through several conductive adhesive dots; and the conductive material 42 filled in the patterned grooves 41 at the negative electrode position can connect the negative electrodes of the BC battery to each other through several conductive adhesive dots (e.g., ...). Figure 2 (As shown). Figure 1The image only shows the etched conductive structure 4, patterned groove 41, and connection channel 1 at the positive or negative electrode on the back of the BC battery. Each window 11 of the connection channel 1 is filled with conductive adhesive 12, forming a corresponding conductive adhesive dot. The patterned groove 41 has a depth of 100-500 nanometers and a width of 50-200 micrometers. A low-resistivity conductive material 42 with a resistivity ≤5 μΩ·cm is filled within the patterned groove 41 to form embedded planar conductive lines on the upper surface of the first acid-absorbing coating and the transparent polymer base layer. This conductive material 42 is preferably a nanowire or cured conductive silver paste.

[0036] The insulating encapsulation layer 2 covers the etched conductive structure 4. Specifically, the insulating encapsulation layer 2 is disposed on the upper surface of the etched conductive structure 4 and the first acid-absorbing coating 3, and is formed by integral coating or lamination. This insulating encapsulation layer 2 covers all conductive lines except for specific connection points (the specific connection points refer to the conductive adhesive dots formed by the connection channel 1 for connecting the electrodes of the BC battery), providing insulation protection. The insulating encapsulation layer 2 is a cross-linked polyolefin film (such as POE encapsulation film), an ethylene-vinyl acetate copolymer film (EVA encapsulation film), a multifunctional acrylic adhesive layer, an epoxy coating, or other photovoltaic encapsulation films. The thickness of the insulating encapsulation layer 2 is 3-10 micrometers.

[0037] The connection channel 1 includes several spaced windows 11 partially opened at the corresponding electrode positions on the back of the BC battery in the insulating encapsulation layer 2, and conductive adhesive 12 filled in the windows 11. Each window 11 corresponds to an electrode contact point on the back of the BC battery.

[0038] Specifically, based on the precise positions of the positive and negative electrodes on the back of the BC battery, selective windows are made in the insulating encapsulation layer 2 to form precise connection windows 11 that penetrate the upper and lower surfaces of the insulating encapsulation layer 2 and partially expose the etched conductive structure 4 underneath. Conductive adhesive 12 is filled into the window 11 to form ohmic contact with the corresponding electrodes on the back of the BC battery during lamination. The upper end of the conductive adhesive 12 extends above the insulating encapsulation layer 2, and the lower end of the conductive adhesive 12 is in electrical contact with the etched conductive structure 4. The conductive adhesive 12 can be anisotropic or isotropic.

[0039] The present invention provides a method for preparing a conductive integrated encapsulation material for BC batteries, comprising the following steps: Step 1. Preparation of transparent polymer base layer 5: Provide a transparent PET film or PI film with a thickness of 10-20 micrometers as the transparent polymer base layer 5.

[0040] Step 2. Preparation of acid-absorbing coating: Use 50-60 parts (by weight, the same below) of low-acid acrylic resin with an acid value ≤5mg KOH / g, add 8-12 parts of curing agent, 0.3-0.5 parts of leveling agent, 0.3-0.6 parts of ultraviolet light absorber, 0.3-0.5 parts of defoamer, 1.3-2.0 parts of acid-absorbing filler, 1.5-3 parts of thermally conductive-radiative heat dissipation filler, and 20-40 parts of solvent, mix evenly to obtain acid-absorbing coating (i.e., acrylic coating).

[0041] The curing agent is an isocyanate curing agent, preferably an HDI (hexamethylene diisocyanate) trimer; the leveling agent is at least one of leveling agent BYK300 and leveling agent BYK330; the ultraviolet absorber is at least one of Tinuvin 479 and TINUVIN400; the defoamer is at least one of defoamer BYK066N and defoamer BYK065; and the solvent is at least one of butyl acetate and propylene glycol methyl ether acetate.

[0042] Step 3. Preparation of acid-absorbing coating: Using microgravure coating technology, the acid-absorbing coating from step 2 is applied to the upper and lower surfaces of the transparent polymer base layer 5 and cured to obtain the first acid-absorbing coating 3 and the second acid-absorbing coating 6, respectively.

[0043] Step 4. Fabrication of patterned grooves 41: Based on the back interconnection circuit pattern design of the BC battery, patterned grooves 41 are etched on the upper surface of the first acid-absorbing coating 3 and the transparent polymer base layer 5 using ultraviolet laser engraving or chemical etching processes (the depth of the patterned grooves 41 is 100-500 nanometers and the width is 50-200 micrometers).

[0044] Step 5. Filling conductive material 42 to form conductive lines: Using screen printing, scraping, or inkjet printing, fill the patterned grooves 41 obtained in step 4 with conductive silver paste of suitable viscosity that cures at low temperatures (viscosity 10000-15000 mPa·s) and has low resistivity. Then, dry and / or cure at low temperatures at 100-200°C to form embedded planar conductive lines. After processing in steps 4-5, the etched conductive structure 4 is obtained.

[0045] Step 6. Preparation of insulating encapsulation layer 2: On the upper surface of the etched conductive structure 4 and the first acid-absorbing coating 3, a layer of liquid insulating encapsulation material (such as polyolefin adhesive, multifunctional acrylic adhesive, or epoxy coating) is uniformly coated using a coating machine, and then pre-cured to obtain insulating encapsulation layer 2. Alternatively, a solid insulating encapsulation film (such as POE encapsulation film, EVA encapsulation film, or other photovoltaic encapsulation film) can be directly laminated onto the upper surface of the etched conductive structure 4 and the first acid-absorbing coating 3 to obtain insulating encapsulation layer 2.

[0046] Step 7. Grooving: Using existing infrared vision positioning laser ablation technology, selectively and precisely grooving is performed on the insulating encapsulation layer 2 obtained in step 6 according to the electrode arrangement coordinates on the back of the BC battery. The grooving position is precisely aligned with the predetermined position of the conductive line in step 5. The grooving depth is just enough to partially expose the embedded conductive line of the etched conductive structure 4 below. The grooving is matched with the electrode size on the back of the BC battery to form several spaced windows 11 that partially penetrate the upper and lower surfaces of the insulating encapsulation layer 2 and partially expose the embedded conductive line of the etched conductive structure 4 below.

[0047] Step 8. Filling with conductive adhesive 12: Using high-precision dispensing or printing technology, anisotropic conductive adhesive (ACF) or isotropic conductive adhesive (ICA) is precisely filled into the window 11 formed in step 7 to obtain the connection channel 1.

[0048] Step 9. Winding and Storage: Wind up and store the conductive integrated encapsulation material for the BC battery that has been completed in Step 8 above for future use.

[0049] A BC cell photovoltaic module of the present invention comprises, from bottom to top, the following layers stacked together: a photovoltaic backsheet, a back sealing film, a conductive integrated encapsulation material for BC cells of the present invention (hereinafter referred to as conductive integrated encapsulation material, wherein the conductive adhesive dots of the connection channel 1 of the conductive integrated encapsulation material face upward), a BC cell string (the BC cell string includes several interconnected BC cells, which are interconnected by conductive adhesive 12 and etched conductive structures 4, with the electrodes on the back of the BC cells facing downward), a front sealing film (such as an EVA encapsulation film), and a photovoltaic front panel (such as photovoltaic glass). The stacked structure is placed in a laminator and laminated under vacuum and heating conditions (temperature 145-155°C, pressure above -95kPa). During lamination, the insulating encapsulation layer 2 melts and flows, tightly bonding the BC solar cell to the conductive integrated encapsulation material. Simultaneously, the conductive adhesive 12 within the window 11 of the connecting channel 1 solidifies or sinters under hot pressing, forming a strong, low-resistance electrical connection with the corresponding electrodes (positive and negative) on the back of the BC solar cell. The embedded conductive lines of the etched conductive structure 4 connect the electrodes of the same polarity of multiple solar cells within the same cell string via the conductive adhesive 12, ultimately leading to the string end of the etched conductive structure 4 (i.e., the...). Figure 1-2 The etched conductive structure 4 is shown in the middle horizontal direction. After lamination, the interconnected BC cell photovoltaic module is obtained. This BC cell photovoltaic module does not require an additional solder ribbon welding step.

[0050] The following provides a conductive integrated encapsulation material for BC batteries, its preparation method, and specific embodiments of BC battery photovoltaic modules according to the present invention: Example 1 This embodiment describes a conductive integrated encapsulation material for BC batteries, its preparation method, and a BC battery photovoltaic module. Referring to the specific embodiments described above, the difference between this embodiment and the specific embodiments is as follows: In step 1, a 15μm thick optical-grade transparent PET film with a clean surface is selected as the transparent polymer base layer 5.

[0051] In step 2, the acid-absorbing coating is prepared by using 50 parts (by weight, the same below) of low-acid acrylic resin with an acid value ≤ 5 mg KOH / g, adding 10 parts of HDI (hexamethylene diisocyanate) trimer as a curing agent, adding 0.5 parts of leveling agent BYK330, 0.5 parts of ultraviolet light absorber (Tinuvin 479), 0.5 parts of defoamer BYK065, 1.5 parts of acid-absorbing filler (magnesium hydroxide), 2 parts of thermally conductive-radiative heat dissipation filler (aluminum nitride), and 35 parts of solvent (propylene glycol methyl ether acetate), and mixing them evenly to obtain the acid-absorbing coating (i.e., acrylic coating).

[0052] In step 3, the thickness of both the first acid-absorbing coating 3 and the second acid-absorbing coating 6 is 3 micrometers.

[0053] In step 4, based on the back interconnection circuit diagram of a standard BC battery (size 182mm*91mm), a patterned groove 41 with a depth of 400 nanometers and a width of 80 micrometers is etched on the upper surface of the first acid-absorbing coating 3 and the transparent PET film using ultraviolet laser engraving technology. The pattern includes busbars and fine grid lines corresponding to the positive and negative electrodes of the BC battery.

[0054] In step 5, a low-temperature curing, low-resistivity conductive silver paste with a suitable viscosity (viscosity 12000-15000 mPa·s, resistivity ≤5 μΩ·cm) is screen-printed into the patterned grooves 41. It is then dried and pre-cured in a tunnel oven at 150℃ to form an embedded planar conductive circuit. After steps 4-5, the etched conductive structure 4 is obtained.

[0055] In step 6, a layer of liquid multifunctional acrylic adhesive (80% solid content) is uniformly coated on the upper surface of the etched conductive structure 4 and the first acid-absorbing coating 3 using a coating machine. After pre-curing at 120°C for 90 seconds, a pre-cured insulating encapsulation layer 2 with a thickness of 5μm is obtained. (During the lamination process of the BC cell photovoltaic module, the pre-cured insulating encapsulation layer 2 can be melted and flowed. After lamination, a fully cured insulating encapsulation layer is obtained.)

[0056] The preparation process of the liquid multifunctional acrylic adhesive is as follows: 20wt% trifunctional acrylic resin (F001), 25wt% difunctional acrylic resin (HDDA), 35wt% hexafunctional acrylic resin (E001), 2wt% thermal initiator TBPO, and 18wt% diluent (PMA) are placed in a disperser and dispersed at 3000r / min for 30min to obtain the liquid multifunctional acrylic adhesive.

[0057] In step 7, an existing infrared-CCD vision composite positioning system is used in conjunction with a picosecond laser to selectively ablate windows on the upper surface of the insulating encapsulation layer 2 at positions corresponding to each electrode pad (0.5mm*0.5mm) on the back of the IBC battery, so as to form several spaced windows 11 that partially penetrate the upper and lower surfaces of the insulating encapsulation layer 2 and partially expose the embedded conductive lines of the etched conductive structure 4 below.

[0058] In step 8, anisotropic conductive adhesive (ACF) is precisely applied into each window 11 using a spray dispensing valve to form conductive adhesive dots with an equivalent diameter of 0.5 mm, thus obtaining the connection channel 1.

[0059] The anisotropic conductive adhesive is a conductive adhesive made by dispersing 50wt% nickel-plated polystyrene microspheres as conductive particles in 35wt% acrylate rubber and 15wt% crosslinkable prepolymer (epoxy acrylic resin).

[0060] In step 9, the BC battery conductive integrated encapsulation material finished product that has completed step 8 of this embodiment is rolled up under constant temperature and humidity (25°C, 40%RH) conditions and packaged and stored in black light-proof film for later use.

[0061] Comparative Example 1 This comparative example describes a conductive integrated encapsulation material for BC batteries, its preparation method, and a BC battery photovoltaic module. Referring to Example 1, the difference between this comparative example and Example 1 is: In the preparation of the acrylic coating in step 2 of this comparative example, the 1.5 parts of acid-absorbing filler of Example 1 were not added; and the acrylic coating of this comparative example contained 1.5 more parts of solvent than that of Example 1.

[0062] Comparative Example 2 This comparative example describes a conductive integrated encapsulation material for BC batteries, its preparation method, and a BC battery photovoltaic module. Referring to Example 1, the difference between this comparative example and Example 1 is: In the preparation of the acrylic coating in step 2 of this comparative example, the 2 parts of thermally conductive-radiative heat dissipation filler of Example 1 were not added; and the acrylic coating of this comparative example contained 2 more parts of solvent than that of Example 1.

[0063] Performance testing Performance tests were conducted on the BC cell photovoltaic modules (hereinafter referred to as BC modules) of Example 1 and Comparative Examples 1-2, as well as commercially available BC cell photovoltaic modules. The test results are shown in Table 1 below: Table 1

[0064] Referring to Table 1, it can be seen that Example 1, Comparative Examples 1-2, and commercially available BC cell photovoltaic modules can all achieve conductivity and power output. Compared with commercially available BC cell photovoltaic modules, the BC cell photovoltaic module of Example 1 of this invention, which uses a conductive integrated encapsulation material for BC cells, can significantly reduce its operating temperature, reduce its power degradation rate after damp heat aging (DH2000h), and improve its long-term reliability.

[0065] Moreover, compared to Comparative Examples 1-2, in the conductive integrated encapsulation material for BC batteries in Embodiment 1 of the present invention, the acid-absorbing coating (i.e., acrylic coating) used to form the first acid-absorbing coating and the second acid-absorbing coating is based on low-acid acrylic resin. Through the synergistic cooperation of acid-absorbing filler and thermally conductive-radiative heat dissipation filler, after being applied to BC battery photovoltaic modules, it can effectively reduce the operating temperature of BC battery photovoltaic modules and effectively reduce the power decay rate after damp heat aging (DH2000h), thus greatly improving the long-term reliability of BC battery photovoltaic modules.

[0066] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0067] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A conductive integrated encapsulation material for BC batteries, characterized in that, Includes a transparent polymer base layer, an acid-absorbing coating, an etched conductive structure, an insulating encapsulation layer, and connection channels; The acid-absorbing coating includes a first acid-absorbing coating disposed on the upper surface of a transparent polymer base layer; the etched conductive structure includes patterned grooves formed by local etching on the upper surfaces of the first acid-absorbing coating and the transparent polymer base layer and conductive material filled in the patterned grooves. The patterned grooves correspond to the circuit pattern on the back of the BC battery, so that the conductive material filled in the patterned grooves forms an embedded conductive circuit. The insulating encapsulation layer is disposed on the upper surface of the etched conductive structure and the first acid-absorbing coating; The connection channel includes several windows spaced apart from each other that run through the upper and lower surfaces of the insulating encapsulation layer and conductive adhesive that fills the windows and electrically contacts the etched conductive structure. The conductive adhesive in each window corresponds to an electrode contact position on the back of the BC battery.

2. The conductive integrated encapsulation material for BC batteries according to claim 1, characterized in that, The patterned grooves have an etching depth of 100-500 nanometers and a width of 50-200 micrometers. The conductive material is a low resistivity conductive material with a resistivity ≤5μΩ·cm, which can be selected from nanowires or cured conductive silver paste.

3. The conductive integrated encapsulation material for BC batteries according to claim 1, characterized in that, The acid-absorbing coating further includes a second acid-absorbing coating disposed on the lower surface of the transparent polymer base layer; the first and second acid-absorbing coatings are acrylic coatings with a thickness of 1-3 micrometers; the acrylic coating used to form the acrylic coating comprises 50-60% by weight: A mixture of 1.3-2 and 1.5-3 acrylic resin, acid-absorbing filler, and thermally conductive / radiative heat dissipation filler; The acrylic resin is a low-acid acrylic resin with an acid value ≤ 5 mg KOH / g; the acid-absorbing filler is at least one of calcium carbonate and magnesium hydroxide; the thermally conductive-radiative heat dissipation filler is at least one of boron nitride, aluminum nitride, silicon nitride, carbon nanotubes, and carbon fibers.

4. A conductive integrated encapsulation material for BC batteries according to claim 1 or 3, characterized in that, The acrylic coating further includes additives mixed in a weight ratio of 50-60:28-54; the additives include one or more of curing agents, leveling agents, ultraviolet absorbers, defoamers, and solvents.

5. The conductive integrated encapsulation material for BC batteries according to claim 1, characterized in that, The insulating encapsulation layer is at least one of the following: cross-linked polyolefin film, ethylene-vinyl acetate copolymer film, multifunctional acrylic adhesive layer, and epoxy coating; the thickness of the insulating encapsulation layer is 3-10 micrometers.

6. The conductive integrated encapsulation material for BC batteries according to claim 1, characterized in that, The conductive adhesive is an anisotropic conductive adhesive or an isotropic conductive adhesive. The transparent polymer base layer is a polyethylene terephthalate film or a polyimide film with a thickness of 10-20 micrometers.

7. A method for preparing a conductive integrated encapsulation material for a BC battery according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Prepare the transparent polymer base layer; S2. Prepare a first acid-absorbing coating on the upper surface of a transparent polymer base layer; S3. Based on the circuit pattern on the back of the BC battery, the upper surface of the first acid-absorbing coating and the transparent polymer base layer is etched to form patterned grooves. S4. Fill the patterned grooves with conductive material to obtain an etched conductive structure with embedded conductive lines; S5. An insulating encapsulation layer is formed on the upper surface of the etched conductive structure and the first acid-absorbing coating. S6. Based on the electrode contact position on the back of the BC battery, selectively open windows in the insulating encapsulation layer to form windows for locally exposing embedded conductive lines with etched conductive structures. S7. Fill the window with conductive adhesive.

8. The method for preparing a conductive integrated encapsulation material for a BC battery according to claim 7, characterized in that, In step S3, the upper surfaces of the first acid-absorbing coating and the transparent polymer base layer are etched using ultraviolet laser engraving or chemical etching processes to form the patterned grooves. In step S4, conductive silver paste is filled into the patterned grooves using screen printing, scraping, or inkjet printing processes, and then cured at 100-200°C to form the conductive material.

9. The method for preparing a conductive integrated encapsulation material for a BC battery according to claim 7, characterized in that, Step S2 further includes: preparing a second acid-absorbing coating on the lower surface of the transparent polymer substrate; In step S5, the insulating encapsulation layer is formed by coating liquid insulating encapsulation material using a coating process and then pre-curing it, or by laminating solid insulating encapsulation film using a lamination process. In step S6, a visually-guided laser ablation process is used to selectively open windows to form the window.

10. A photovoltaic module, characterized in that, It includes, from bottom to top, a photovoltaic backsheet, a back sealing film, a conductive integrated encapsulation material, a BC cell, a front sealing film, and a photovoltaic front panel; The conductive integrated encapsulation material is a conductive integrated encapsulation material for BC batteries as described in any one of claims 1-6, and the conductive adhesive connecting the channel faces the electrode on the back of the BC battery.

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