Method and system for bonding flexible module cells and protective layers

Abstract

This invention discloses a method and system for bonding flexible module battery cells and a protective layer, belonging to the field of flexible battery technology. The bonding method includes pre-cutting the surface of the battery cell to form a first pre-cut line; bonding the battery cell and the protective layer with an adhesive and then curing the adhesive; and pre-cutting the surface of the protective layer by aligning with the first pre-cut line to form a second pre-cut line. The adhesive has a viscosity of 500-1500 mPa·s before curing and a light transmittance ≥95%. This invention, by pre-cutting the protective layer with the first pre-cut line, ensures precise alignment between the protective layer and the pre-cut line of the battery cell, improving the accuracy and product quality of subsequent cell splitting processes. The adhesive used in the optimized bonding process of this invention has lower requirements for flowability and viscosity, and higher light transmittance, which helps to improve battery conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the field of flexible battery technology, specifically relating to a method and system for bonding flexible component battery cells and protective layers. Background Technology

[0002] In existing flexible module manufacturing processes, pre-cut lines are typically formed on both the solar cells and the protective layer beforehand, and then CCD alignment technology is used to align and bond the pre-cut lines on both sides. However, this process has some areas for improvement.

[0003] First, if the protective layer has been pre-cut before bonding, it is very easy for the protective layer to crack prematurely during movement or handling, resulting in waste of raw materials.

[0004] Secondly, both the battery cells and the protective layer are pre-cut, which makes the bonding process extremely demanding. During bonding, CCD alignment technology is required to align the pre-cut lines of the battery cells and the protective layer. However, even with this method, the overlap deviation between the pre-cut lines of the protective layer and the battery cells is still relatively large, thus affecting the performance and quality of the battery.

[0005] Third, existing technologies require alignment adjustments after bonding the battery cells and protective layers with adhesive to ensure that the pre-cut lines of the battery cells and protective layers coincide before curing. This requires balancing the flowability and viscosity of the adhesive, which limits the physical properties and optical performance of the adhesive, thereby affecting the conversion efficiency of the battery.

[0006] It should be noted that this part of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or known technology. Summary of the Invention

[0007] This invention aims to at least solve the problems of large overlap deviation between the pre-cut lines on the protective layer and the pre-cut lines on the battery cell, and the poor performance of the adhesive in existing technologies. This invention provides a method and system for bonding flexible module battery cells and a protective layer. By optimizing the bonding process, this invention enables precise alignment of the pre-cut lines on the battery cell and the protective layer. Simultaneously, the adhesive used in the optimized bonding process of this invention helps improve battery conversion efficiency.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a method for bonding a flexible module battery cell and a protective layer, the method comprising the following steps: pre-cutting the surface of the battery cell to form a first pre-cut line; bonding the battery cell and the protective layer together with an adhesive and then curing the adhesive; pre-cutting the surface of the protective layer by aligning the first pre-cut line to form a second pre-cut line; wherein the viscosity of the adhesive before curing is 500-1500 mPa·s, and the light transmittance of the adhesive is ≥95%.

[0009] Furthermore, the adhesive is one or a combination of silicone, EVA, POE, and double-sided tape.

[0010] Furthermore, the adhesive contains the following components by weight percentage: 60-80% vinyl silicone oil, 10-25% crosslinking agent, 5-10% platinum catalyst, 1-5% filler, and 1%-3% tackifier.

[0011] Furthermore, the phenyl vinyl silicone oil content in the vinyl silicone oil is 20-50%.

[0012] Furthermore, the crosslinking agent is selected from one or a combination of hydrogen-containing silicone oil and methyl vinyl MQ silicone resin.

[0013] Furthermore, the platinum catalyst is selected from one or a combination of vinylsiloxane platinum complex and chloroplatinic acid catalyst.

[0014] Furthermore, the filler is selected from one or a combination of silica aerogel and modified silica aerogel.

[0015] Furthermore, the tackifier is α,ω-dihydroxypolysiloxane.

[0016] Furthermore, the hardness of the cured adhesive is 30-55 Shore A.

[0017] Furthermore, the curing temperature of the adhesive is 60-110℃, and the curing time is 30-60 minutes.

[0018] Furthermore, the ratio of the first pre-cut line to the thickness of the solar cell ranges from 1 / 3 to 2 / 3, and the maximum width of the first pre-cut line ranges from 10μm to 50μm.

[0019] Furthermore, the ratio of the second pre-cut line to the thickness of the protective layer ranges from 1 / 5 to 3 / 5, and the maximum width of the second pre-cut line ranges from 10μm to 80μm.

[0020] Furthermore, the protective layer surface is pre-cut using laser cutting. The laser focus is positioned 1 / 3 to 2 / 3 of the way down from the upper surface of the protective layer away from the battery cell. The laser power for laser cutting is greater than or equal to 50W, the laser wavelength is 532nm, the pulse width is less than 15PS, the single pulse energy is greater than 200uJ, the laser pulse repetition frequency is 20kHz-1MHz, and the cutting speed is 1mm / s-3000mm / s.

[0021] Furthermore, after forming the second pre-cut line, the process also includes:

[0022] Remove any loose edges from the protective layer;

[0023] The protective layer, adhesive, and battery cells are split to form multiple small battery cells.

[0024] Secondly, the present invention provides a bonding system for flexible module solar cells and a protective layer. The bonding system is applied to a bonding method for flexible module solar cells and a protective layer. The bonding system includes a pre-cutting device, a bonding device, and an alignment device. The pre-cutting device is used to pre-cut the surface of the solar cell to form a first pre-cutting line and to pre-cut the surface of the protective layer to form a second pre-cutting line. The bonding device is used to bond the solar cell and the protective layer with adhesive and then cure the adhesive. The alignment device is used to assist the pre-cutting device in aligning the first pre-cutting line.

[0025] The beneficial effects of this invention are:

[0026] This invention, through the aforementioned technical solution, specifically involves pre-cutting the surface of the battery cell to form a first pre-cutting line; bonding the battery cell and protective layer with adhesive and then curing the adhesive; and pre-cutting the surface of the protective layer by aligning with the first pre-cutting line to form a second pre-cutting line. The adhesive, before curing, has a viscosity of 500-1500 mPa·s and a light transmittance ≥95%. By pre-cutting the protective layer after bonding, this invention avoids the risk of premature cracking during movement or handling, significantly reducing product defect rates. Furthermore, by pre-cutting the protective layer by aligning with the first pre-cutting line, this invention ensures precise alignment between the protective layer and the pre-cutting line of the battery cell, improving the accuracy of subsequent cell dicing processes and product quality.

[0027] Furthermore, this invention, through process optimization of first bonding and curing followed by pre-cutting of the protective layer, successfully solves the problem of balancing the flowability and tackiness of the adhesive in existing technologies. The adhesive used in the optimized bonding process of this invention has lower requirements for flowability and tackiness. This invention improves the composition of the adhesive to increase light transmittance, which helps to improve battery conversion efficiency.

[0028] Furthermore, existing technologies can only achieve a maximum alignment and bonding accuracy deviation of 20-50 μm, resulting in low bonding accuracy and a high failure rate in subsequent cell cleaving, leading to low battery production yield. However, using the technical solution of this invention, the bonding accuracy deviation can be reduced to less than 10 μm, thereby significantly improving the cell cleaving yield.

[0029] The flexible module cell and protective layer bonding system of the present invention includes a pre-cutting device, a bonding device and an alignment device. The devices work together to achieve a highly efficient and stable bonding process, further improving production efficiency and product quality. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart illustrating the bonding method between the flexible module battery cell and the protective layer provided in Embodiment 1 of the present invention.

[0032] Figure 2 This is a flowchart illustrating the bonding method of flexible module battery cells and protective layers provided in Comparative Example 1 of the present invention. Detailed Implementation

[0033] In this invention, unless otherwise stated, directional terms such as "up," "down," "left," and "right" are generally understood in conjunction with the accompanying drawings and the directions shown in actual applications.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. The terms "optional" and "discretionary" mean that they may or may not be included (or may or may not be present).

[0037] This invention provides a method for bonding a flexible module battery cell and a protective layer. The method includes the following steps: pre-cutting the surface of the battery cell to form a first pre-cut line; bonding the battery cell and the protective layer with an adhesive and then curing the adhesive; pre-cutting the surface of the protective layer by aligning with the first pre-cut line to form a second pre-cut line; wherein the viscosity of the adhesive before curing is 500-1500 mPa·s, and the light transmittance of the adhesive is ≥95%.

[0038] In existing technologies, pre-cutting of the battery cells and protective layer can easily lead to premature cracking of the protective layer during handling. This invention places the pre-cutting process of the protective layer after lamination, thereby reducing product defect rates. Furthermore, existing technologies often suffer from significant alignment deviations in the pre-cutting lines, affecting the accuracy of subsequent cell dicing processes. This invention ensures precise alignment of the pre-cutting lines by aligning the first pre-cutting line, improving the accuracy of the dicing process and product quality. In addition, this invention's optimized process of lamination followed by curing eliminates the need to balance the flowability and viscosity of the adhesive, as required by existing technologies. This allows for further optimization of the adhesive composition to improve light transmittance, contributing to increased battery conversion efficiency.

[0039] The following will explain in detail the principle behind the improved bonding process of this invention:

[0040] Existing technologies typically involve pre-cutting both the battery cell and the protective layer to form pre-cut lines, and then using CCD alignment technology to align and bond the pre-cut lines on both sides.

[0041] This process has some areas for improvement. First, in existing technologies, the cells and protective layer are pre-cut. The cells themselves are relatively rigid and not easily broken before bonding. However, the protective layer is a brittle material layer, which can be made of glass, PC, PMMA, PP, PET, or transparent fluoropolymer. These materials are brittle and are prone to cracking during handling. In contrast, this invention places the pre-cutting process of the protective layer after bonding, thus eliminating this risk and reducing the product defect rate.

[0042] It should be noted that the purpose of pre-cutting both the solar cells and the protective layer to create pre-cut lines in existing technologies is to separate the pre-cutting process from the bonding process. Since production efficiency primarily depends on the bonding speed, pre-cutting the solar cells and protective layer can improve efficiency. However, as mentioned earlier, this pre-cutting technique leads to significant overlap and deviation between the pre-cut lines on the protective layer and the pre-cut lines on the solar cells. With the continuous development of the photovoltaic industry, the requirements for cell quality are becoming increasingly stringent. While this existing technology offers high production efficiency, it can no longer meet the ever-growing demands for cell quality.

[0043] Secondly, existing technologies use CCD alignment to align and bond pre-cut lines on both sides. However, because the pre-cut lines on the battery cell and the protective layer are pre-cut separately, they are not aligned during the cutting process, inherently introducing some error. Furthermore, the CCD alignment technology also has errors in recognizing the pre-cut lines. The combined effect of these errors results in a significant overlap deviation between the pre-cut lines on the battery cell and the protective layer. In contrast, this invention first forms a first pre-cut line on the battery cell. After bonding the battery cell and the protective layer, a second pre-cut line is formed on the protective layer by aligning the first pre-cut line. This ensures precise alignment of the pre-cut lines on the battery cell and the protective layer, improving the accuracy of subsequent dicing processes and product quality.

[0044] Third, in existing technologies for aligning and bonding solar cells and protective layers, it's unrealistic to directly align the pre-cut lines on the solar cells and protective layers in a single positioning step. In practice, the alignment and bonding process involves first applying adhesive between the solar cells and the protective layer, then layering them, and performing multiple fine-tuning adjustments to reduce the overlap of the pre-cut lines. However, because adhesive is already applied between the solar cells and the protective layer, the adhesive must have high fluidity. Otherwise, if the adhesive is too viscous, it will directly adhere the solar cells and protective layer, making fine-tuning impossible. On the other hand, if the adhesive is too fluid, the solar cells and protective layer may shift again after the alignment is completed, causing further deviation. In summary, the existing alignment and bonding process places very high demands on the adhesive, requiring a balance between its fluidity and viscosity.

[0045] Furthermore, although the flowability, viscosity, and transmittance of adhesives used in the photovoltaic field are not simply linearly related, the adjustments made to the composition of adhesives to balance their flowability and viscosity will significantly reduce their transmittance. Low transmittance will first reduce the accuracy of the double-sided pre-cut line alignment and bonding of existing CCD alignment technology, and will also affect the subsequent light transmission through the protective layer and adhesive into the solar cell, thereby reducing the cell conversion efficiency.

[0046] Meanwhile, existing technologies also suffer from the problem of mutual constraints between the bonding process and the properties of the adhesive. First, it must be emphasized that when those skilled in the art want to improve the bonding process, they cannot conceive of exchanging the order of pre-cutting and bonding / curing without technical inspiration. Furthermore, even if the present invention were to adopt the method of bonding / curing before cutting, the process requires high light transmittance of the adhesive. The low light transmittance of adhesives in existing technologies affects the identification of pre-cut lines, failing to meet the requirement of bonding / curing before cutting in the present invention. In this case, improving the process requires simultaneous and coordinated improvements to the production line, equipment, and adhesive, necessitating creative effort from those skilled in the art. On the other hand, when those skilled in the art want to improve the adhesive, existing bonding processes require an adhesive that balances flowability and viscosity, making it difficult to find an adhesive that simultaneously meets these requirements and possesses high light transmittance.

[0047] Furthermore, there is no research in the existing technology on the relationship between the pre-cutting method, the bonding method and the overlap deviation of the pre-cutting line. At the same time, the existing technology is also limited by the properties of the adhesive. Without technical inspiration, those skilled in the art cannot know or have the motivation to improve the existing technology.

[0048] In summary, it can be seen that the existing bonding process system consists of three parts: "pre-cutting both the battery cell and the protective layer, aligning and bonding the two, and using an adhesive that balances flowability and tack." It is difficult to solve the problem of large overlap deviation of the pre-cut lines by changing only one step. How to reduce the overlap deviation between the pre-cut lines on the protective layer and the pre-cut lines on the battery cell has become a technical problem that those skilled in the art urgently want to solve.

[0049] Therefore, this invention, through process optimization of bonding and curing before cutting, eliminates the need for fine-tuning the positioning of the battery cells and protective layer during bonding. This reduces the requirements for the fluidity and tackiness of the adhesive, allowing for further optimization of the adhesive composition to improve light transmittance. The high light transmittance also meets the requirement of the new bonding process of bonding and curing before cutting, while simultaneously contributing to improved battery conversion efficiency. The bonding method and adhesive of this invention work synergistically to form a completely new bonding process system, demonstrating significant benefits in reducing product defect rates, improving cell cutting accuracy, and enhancing battery conversion efficiency.

[0050] Furthermore, since the positions of the battery cells and the protective layer do not require fine-tuning, there is no need to worry about displacement caused by fine-tuning during the bonding process of the battery cells and the protective layer. This can prevent misalignment of the pre-cutting lines of the battery cells and the protective layer and avoid reducing product yield.

[0051] It should be noted that the viscosity of the adhesive before curing is 500-1500 mPa·s. The viscosity of the adhesive before curing can be 500 mPa·s, 800 mPa·s, 1000 mPa·s, 1200 mPa·s, 1500 mPa·s, or any value in between.

[0052] Preferably, the viscosity test method for the adhesive before curing refers to GB / T 2794-2013, which involves continuously rotating an LV series rotor at 12 revolutions per minute for 2 minutes at 25±0.5℃, and then taking the reading after stabilization.

[0053] It should be noted that adhesives in the prior art must balance flowability and tackiness; therefore, the viscosity range of adhesives in the prior art is typically between 2000-3000 mPa·s. Generally speaking, the higher the viscosity of the adhesive before curing, the lower its flowability and the higher its tackiness; conversely, the lower the viscosity of the adhesive before curing, the higher its flowability and the lower its tackiness. Therefore, the prior art must maintain the viscosity within the above range to balance flowability and tackiness.

[0054] Furthermore, compared to existing technologies that require adhesives with balanced flowability and viscosity, the bonding method of this invention does not have specific requirements for the flowability and viscosity of the adhesive. Theoretically, this invention can choose adhesives of any viscosity, all of which should be within the scope of protection of this invention. Moreover, based on the new bonding process, this invention selects a suitable viscosity of the adhesive before curing, which can better bond and cure the adhesive, thereby improving the light transmittance of the adhesive.

[0055] This invention uses an adhesive with appropriate viscosity, which can not only improve light transmittance, but also penetrate faster and improve wettability, further optimizing the initial tack, final adhesion strength, adhesion performance and filling performance of the adhesive, which can ensure a firm bond between the battery cell and the protective layer and improve the battery yield.

[0056] Furthermore, existing adhesives may cause surface unevenness, bubble formation, or affect the optical properties after curing during pressure bonding, thereby reducing light transmittance. The adhesive of this invention, with its suitable viscosity, solves the inherent defects of existing multifunctional adhesives that require a balance between flowability and viscosity, providing a superior solution for flexible component manufacturing.

[0057] It should be noted that the light transmittance of the adhesive of the present invention is ≥95%. For example, the light transmittance of the adhesive can be 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, higher, and any value between them.

[0058] Preferably, the method for testing the transmittance of the adhesive is to prepare a smooth and flat sample with a thickness of 1.0±0.1mm, and use a spectrophotometer to measure the proportion of transmitted light flux of the cured adhesive layer in the wavelength range of 300-1100nm.

[0059] It should be noted that the adhesives in the existing technology are limited by the requirements of flowability and viscosity balance, and the viscosity range is usually between 2000-3000 mPa·s. From the perspective of component compounding, the light transmittance is difficult to exceed 93% at most.

[0060] Understandably, high light transmittance in adhesives helps improve cell conversion efficiency because it allows more light to pass through, thus increasing the amount of light energy received by the cells. In photovoltaic cells, light energy is the key factor in converting light into electrical energy. More light energy absorbed by the cells means more photons can excite electrons to generate current, thereby improving the cell's power generation efficiency. Furthermore, high light transmittance adhesives can reduce light reflection and scattering, lowering energy loss and further enhancing the cell's light absorption efficiency and overall performance.

[0061] Furthermore, besides improving battery conversion efficiency, the light transmittance of the adhesive also affects the pre-cutting of the protective layer surface to form the second pre-cutting line by aligning the first pre-cutting line. Specifically, the flexible component structure of this invention consists of a protective layer, adhesive, and battery cells arranged sequentially. Therefore, when aligning the first pre-cutting line, visual recognition of the first pre-cutting line is required through the protective layer and adhesive. Thus, the light transmittance of the adhesive also determines the accuracy of aligning the first pre-cutting line, thereby affecting the overlap deviation between the battery cells and the protective layer pre-cutting lines. Therefore, directly using existing adhesives to match the pre-bonding and curing then cutting technique of this invention is impractical, because the low light transmittance of existing adhesives cannot meet the process requirements of the new bonding process. Too low a light transmittance leads to blurred visual recognition, resulting in a significant increase in overlap deviation.

[0062] Furthermore, the adhesive is one or a combination of silicone, EVA, POE, and double-sided tape. This invention does not impose any particular limitation on the type of adhesive; if an adhesive in the prior art can achieve the viscosity and light transmittance effects mentioned in this invention, it is also within the scope of protection of this invention.

[0063] To further adapt to the process of this invention, the present invention also provides an improved silicone adhesive. Further, the adhesive comprises the following components in weight percentages: 60-80% vinyl silicone oil, 10-25% crosslinking agent, 5-10% platinum catalyst, 1-5% filler, and 1%-3% tackifier.

[0064] Preferably, the vinyl silicone oil has a mass percentage of 60-80%, which can be 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80%, and any value between them.

[0065] Preferably, the phenyl vinyl silicone oil content in the vinyl silicone oil is 20-50%, and can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, and any value between them.

[0066] Furthermore, the phenyl vinyl silicone oil content in vinyl silicone oil has a significant impact on the viscosity, weather resistance, and light transmittance of the adhesive. Firstly, this invention utilizes vinyl silicone oil to provide basic flexibility, adhesion, and curing properties to silicone adhesives; and by adjusting the phenyl vinyl silicone oil content, the phenyl groups in the phenyl vinyl silicone oil can combine with vinyl groups to further improve the transparency and optical properties after curing, reducing turbidity or light scattering caused by material curing. This invention optimizes the viscosity and light transmittance of the adhesive by increasing the phenyl vinyl silicone oil content in vinyl silicone oil, ensuring good adhesion and improving the photoelectric conversion efficiency of the battery.

[0067] Preferably, the mass percentage of the crosslinking agent is 10-25%, and can be 10%, 13%, 15%, 18%, 20%, 23%, 25%, and any value between them.

[0068] Furthermore, the crosslinking agent is selected from one or a combination of hydrogen-containing silicone oil and methyl vinyl MQ silicone resin. The crosslinking agent is used to react with vinyl silicone oil to cure the silicone and form a three-dimensional network structure, thereby improving the strength, hardness, and other properties of the silicone.

[0069] Preferably, the platinum catalyst has a mass percentage of 5-10%, which can be 5%, 6%, 7%, 8%, 9%, 10%, and any value between them.

[0070] Furthermore, the platinum catalyst is selected from one or a combination of vinylsiloxane platinum complexes and chloroplatinic acid catalysts. The platinum catalyst is used for addition catalysis, effectively accelerating the crosslinking reaction between the crosslinking agent and vinyl silicone oil, allowing the silicone to cure within a suitable time and improving production efficiency.

[0071] Preferably, the mass percentage of the filler is 1-5%, which can be 1%, 2%, 3%, 4%, 5% and any value between them.

[0072] Furthermore, the filler is selected from one or a combination of silica aerogel and modified silica aerogel. The filler can improve the UV aging resistance of silicone and enhance its thermal insulation properties.

[0073] Preferably, the tackifier is 1%-3% by mass, and can be 1%, 1.5%, 2%, 2.5%, 3% and any value between them.

[0074] Furthermore, the tackifier is α,ω-dihydroxypolysiloxane. α,ω-dihydroxypolysiloxane has good viscosity, which can further improve the adhesive performance and ensure the stability of the component structure.

[0075] It should be noted that, without significantly altering the viscosity and light transmittance of the adhesive, other additives can be selectively added according to the actual application scenario. These additives may include, but are not limited to, antioxidants, hydrophobic agents, and leveling agents.

[0076] Furthermore, the hardness of the cured adhesive is 30-55 Shore A. The adhesive obtained by the improved composition of this invention has a lower cured hardness, better flexibility, less stress required for cracking, a smoother cracking process, and cleaner crack edges, which helps to improve the efficiency and quality of cracking.

[0077] Furthermore, the curing temperature of the adhesive is 60-110℃, and the curing time is 30-60 minutes. The reasonable curing temperature and curing time of this invention ensure that the adhesive cures within a reasonable time, achieving the required hardness and bonding strength, while not adversely affecting the material properties of the battery cell and the protective layer.

[0078] Furthermore, the ratio of the first pre-cut line to the thickness of the solar cell ranges from 1 / 3 to 2 / 3, and the maximum width of the first pre-cut line ranges from 10μm to 50μm. A reasonable depth and width of the first pre-cut line can reduce the loss of effective solar cell area and prevent breakage or cracking before bonding, facilitating subsequent bonding and cracking operations while minimizing the loss of solar module efficiency.

[0079] Furthermore, the ratio of the second pre-cut line to the thickness of the protective layer ranges from 1 / 5 to 3 / 5, and the maximum width of the second pre-cut line ranges from 10μm to 80μm. A reasonable depth and width of the second pre-cut line ensures the consistency of the protective layer's pre-cut lines, which is beneficial for subsequent dicing operations.

[0080] Furthermore, the protective layer surface is pre-cut using laser cutting. The laser focus is positioned 1 / 3 to 2 / 3 of the way down from the upper surface of the protective layer away from the battery cell. The laser power for laser cutting is greater than or equal to 50W, the laser wavelength is 532nm, the pulse width is less than 15PS, the single pulse energy is greater than 200uJ, the laser pulse repetition frequency is 20kHz-1MHz, and the cutting speed is 1mm / s-3000mm / s.

[0081] It should be noted that in existing technologies, the laser focus for pre-cutting the protective layer surface is generally located at 1 / 2 to 3 / 4 of the protective layer surface. In existing technologies, the ratio of the second pre-cut line to the protective layer thickness is generally between 1 / 3 and 2 / 3.

[0082] Understandably, compared to existing technologies, the laser focus used for pre-cutting the protective layer surface in this invention is shallower. Therefore, the depth of the second pre-cut line on the protective layer is also shallower. The specific reason is that laser cutting technology is generally used, and the high temperatures generated during laser cutting may cause thermal degradation of the adhesive or damage to the underlying battery cells. To avoid this, this invention adjusts the focal depth of the laser pre-cutting of the protective layer, making it shallower. This avoids damage to the battery cells during the protective layer cutting process. Simultaneously, the adhesive has high light transmittance, which reduces laser absorption during laser cutting, effectively preventing oxidative degradation of the adhesive and maintaining its performance. Furthermore, the shallower focal depth of the cutting laser also reduces the cutting depth of the second pre-cut line, further reducing the risk of the protective layer cracking prematurely before the cell cleaving process, thus contributing to improved battery yield.

[0083] It is understandable that, due to the excellent properties of the adhesive of this invention, even if the cutting depth of the second pre-cutting line of this invention is shallower than that of the prior art, the protective layer can still crack well during the splitting process.

[0084] Understandably, compared to existing technologies, the laser cutting used in this invention has a lower overall intensity, which can avoid damaging the underlying battery cells and adhesive when pre-cutting the protective layer.

[0085] Furthermore, after forming the second pre-cut line, the process also includes:

[0086] Remove any loose edges from the protective layer;

[0087] The protective layer, adhesive, and battery cells are split to form multiple small battery cells.

[0088] It is understood that the first pre-cutting line, the second pre-cutting line, and the adhesive obtained by using the present invention are more conducive to subsequent dicing operations.

[0089] It is understood that the present invention does not have any particular limitations on the specific steps for removing waste edges and battery cracks, and can refer to existing technologies.

[0090] Secondly, the present invention provides a bonding system for flexible module solar cells and a protective layer. The system is applied to a bonding method for flexible module solar cells and a protective layer. The system includes a pre-cutting device, a bonding device, and an alignment device. The pre-cutting device is used to pre-cut the surface of the solar cell to form a first pre-cutting line and to pre-cut the surface of the protective layer to form a second pre-cutting line. The bonding device is used to bond the solar cell and the protective layer with adhesive and then cure the adhesive. The alignment device is used to assist the pre-cutting device in aligning the first pre-cutting line.

[0091] In practical use, the surface of the battery cell is pre-cut by a pre-cutting device to form a first pre-cutting line; the battery cell and the protective layer are bonded together by an adhesive using a bonding device and then the adhesive is cured. At this time, the alignment device and the pre-cutting device are both located above the protective layer, and the adhesive and the battery cell are arranged in sequence below the protective layer; the alignment device assists the pre-cutting device in aligning with the first pre-cutting line to pre-cut the surface of the protective layer to form a second pre-cutting line.

[0092] Furthermore, the pre-cutting device can be a laser cutting device, the alignment device can be a CCD alignment device, and the bonding device can include an adhesive application module for applying adhesive between the battery cell and the protective layer, a pressing module for pressing the protective layer onto the battery cell, and a thermosetting module for thermosetting the adhesive.

[0093] Furthermore, the system may also include a waste edge removal device for removing waste edges from the protective layer, and a cleaving device for cleaving the protective layer, adhesive, and battery cells.

[0094] The present invention is illustrated in detail below by way of examples, but the present invention is not limited to these examples in any way.

[0095] Example 1

[0096] like Figure 1 As shown, a method for bonding flexible module solar cells and a protective layer includes the following steps:

[0097] Pre-cutting is performed on the surface of the battery cell to form a first pre-cut line;

[0098] After the battery cells and protective layer are bonded together with adhesive, the adhesive is cured.

[0099] The protective layer surface is pre-cut by aligning the first pre-cut line to form the second pre-cut line.

[0100] The protective layer surface is pre-cut using laser cutting, with the laser focus positioned 1 / 3 to 2 / 3 of the way down from the upper surface of the protective layer away from the battery cell.

[0101] The adhesive in this embodiment consists of the following components by weight percentage: 70% vinyl silicone oil, 19% crosslinking agent, 5% platinum catalyst, 5% filler, and 1% tackifier.

[0102] In this embodiment, the phenyl vinyl silicone oil content is 35%, the crosslinking agent is methyl vinyl MQ silicone resin, the platinum catalyst is vinyl siloxane platinum complex, the filler is silica aerogel, and the tackifier is α,ω-dihydroxy polysiloxane.

[0103] The viscosity of the adhesive before curing is 1200 mPa·s, and the light transmittance of the adhesive is 98%.

[0104] Example 2

[0105] The bonding method of the flexible module cell and the protective layer in Example 2 is the same as that provided in Example 1, except that the phenyl vinyl silicone oil content in the vinyl silicone oil used in Example 2 is 20%.

[0106] The viscosity of the adhesive before curing is 800 mPa·s, and the light transmittance of the adhesive is 96%.

[0107] Example 3

[0108] The bonding method of the flexible module cell and the protective layer in Example 3 is the same as that provided in Example 1, except that the phenyl vinyl silicone oil content in the vinyl silicone oil used in Example 3 is 50%.

[0109] The viscosity of the adhesive before curing is 1500 mPa·s, and the light transmittance of the adhesive is 99%.

[0110] Example 4

[0111] The bonding method of the flexible module cell and protective layer in Example 4 is the same as that provided in Example 1, except that the adhesive in Example 4 is composed of the following components by mass percentage: 60% vinyl silicone oil, 22% crosslinking agent, 10% platinum catalyst, 5% filler, and 3% tackifier.

[0112] The viscosity of the adhesive before curing is 500 mPa·s, and the light transmittance of the adhesive is 95%.

[0113] Example 5

[0114] The bonding method of the flexible module cell and protective layer in Example 5 is the same as that provided in Example 1, except that the adhesive in Example 5 is composed of the following components by mass percentage: 80% vinyl silicone oil, 12% crosslinking agent, 5% platinum catalyst, 2% filler, and 1% tackifier.

[0115] The viscosity of the adhesive before curing is 1000 mPa·s, and the light transmittance of the adhesive is 97%.

[0116] Comparative Example 1

[0117] like Figure 2 As shown, Comparative Example 1 uses existing technology to bond flexible module cells and protective layers. The method includes the following steps:

[0118] The surface of the battery cell is pre-cut to form a first pre-cut line, and the surface of the protective layer is pre-cut to form a second pre-cut line;

[0119] After bonding the battery cell and the protective layer with adhesive, the first pre-cut line and the second pre-cut line are aligned.

[0120] After alignment, the adhesive will be cured.

[0121] The adhesive used is a commonly used adhesive in existing technologies. The viscosity of the adhesive before curing is 2500 mPa·s, and the light transmittance of the adhesive is 92%.

[0122] Comparative Example 2

[0123] The bonding method of the flexible module cell and protective layer in Comparative Example 2 is the same as that provided in Comparative Example 1, except that the adhesive used in Comparative Example 2 is the adhesive used in the method provided in Example 1.

[0124] Comparative Example 3

[0125] The bonding method of the flexible module cell and protective layer in Comparative Example 3 is the same as that provided in Example 1, except that the adhesive used in Comparative Example 3 is the same adhesive used in the method provided in Comparative Example 1.

[0126] Comparative Example 4

[0127] The bonding method of the flexible module cell and the protective layer in Comparative Example 4 is the same as that provided in Example 1, except that in Comparative Example 4, the laser focus is positioned 1 / 2 to 3 / 4 of the way down from the upper surface of the protective layer away from the cell.

[0128] Test case

[0129] The flexible components obtained in the examples and comparative examples were tested, and the results are shown in Table 1. The alignment and bonding accuracy deviation refers to the deviation distance between the center lines of the first and second pre-cut lines, and the battery cell breakage control yield refers to the pass rate of defective battery cells after removing broken cells from each batch of 1000 cells.

[0130] Table 1

[0131]

[0132] As shown in Table 1, according to Examples 1 to 5, the preferred adhesive composition and proportioning parameters of this invention can effectively improve the light transmittance of the adhesive, further enhancing the battery conversion efficiency of the flexible module. Using the preferred adhesive of this invention also helps to further reduce alignment and bonding accuracy deviations and improve battery yield.

[0133] A comparison of Comparative Example 1 and Example 1 shows that the protective layer of the present invention is pre-cut after lamination, which avoids the risk of premature cracking during movement or handling, and significantly improves product yield. The present invention pre-cuts the protective layer by aligning it with the first pre-cutting line, ensuring precise alignment between the protective layer and the pre-cutting line of the battery cell, effectively reducing alignment and lamination accuracy deviation.

[0134] Comparing Comparative Examples 1 and 2 with Example 1, it can be seen that the present invention, through process optimization of first bonding and curing followed by pre-cutting of the protective layer, successfully solves the problem of high fluidity requirements for adhesives in existing technologies. The adhesive used in the optimized bonding process of the present invention has even lower fluidity requirements. Furthermore, the present invention improves the composition of the adhesive to increase light transmittance, which helps to improve battery conversion efficiency.

[0135] Based on the comparison between Comparative Example 3 and Example 1, it can be seen that the adhesive used in the optimized bonding process of the present invention has higher light transmittance, which helps to improve battery conversion efficiency and further reduce alignment and bonding accuracy deviation and improve battery yield.

[0136] Based on the comparison between Comparative Example 4 and Example 1, it can be seen that the present invention adjusts the focal depth of the pre-cutting laser of the protective layer to make the focal depth shallower, thereby avoiding damage to the battery cell and adhesive during the protective layer cutting process.

[0137] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for bonding flexible module solar cells and a protective layer, characterized in that, The method includes the following steps: Pre-cutting is performed on the surface of the battery cell to form a first pre-cut line; The battery cell and the protective layer are bonded together using adhesive, and then the adhesive is cured. The protective layer surface is pre-cut by aligning the first pre-cut line to form the second pre-cut line; The adhesive has a viscosity of 500-1500 mPa·s before curing and a light transmittance of ≥95%. The adhesive comprises the following components by weight percentage: 60-80% vinyl silicone oil, 10-25% crosslinking agent, 5-10% platinum catalyst, 1-5% filler, and 1%-3% tackifier.

2. The bonding method for flexible module battery cells and protective layers according to claim 1, characterized in that, The phenyl vinyl silicone oil in the vinyl silicone oil contains 20-50%.

3. The bonding method for flexible module solar cells and protective layers according to claim 1, characterized in that, The crosslinking agent is selected from one or a combination of hydrogen-containing silicone oil and methyl vinyl MQ silicone resin; And / or, The platinum catalyst is selected from one or a combination of vinylsiloxane platinum complex and chloroplatinic acid catalyst; And / or, The filler is selected from one or a combination of silica aerogel and modified silica aerogel; And / or, The tackifier is α,ω-dihydroxypolysiloxane.

4. The bonding method for flexible module battery cells and protective layers according to claim 1, characterized in that, The hardness of the adhesive after curing is 30-55 Shore A.

5. The bonding method for flexible module battery cells and protective layers according to claim 1, characterized in that, The curing temperature of the adhesive is 60-110℃, and the curing time is 30-60 minutes.

6. The bonding method for flexible module battery cells and protective layers according to claim 1, characterized in that, The ratio of the first pre-cut line to the thickness of the battery cell ranges from 1 / 3 to 2 / 3, and the maximum width of the first pre-cut line ranges from 10μm to 50μm.

7. The bonding method for flexible module solar cells and protective layers according to claim 1, characterized in that, The ratio of the second pre-cut line to the thickness of the protective layer ranges from 1 / 5 to 3 / 5, and the maximum width of the second pre-cut line ranges from 10μm to 80μm.

8. The bonding method for flexible module battery cells and protective layers according to claim 1, characterized in that, The protective layer surface is pre-cut using laser cutting. The laser focus is positioned 1 / 3 to 2 / 3 of the way down from the upper surface of the protective layer away from the battery cell. The laser power is greater than or equal to 50W, the laser wavelength is 532nm, the pulse width is less than 15PS, the single pulse energy is greater than 200uJ, the laser pulse repetition frequency is 20kHz-1MHz, and the cutting speed is 1mm / s-3000mm / s.

9. The bonding method for flexible module solar cells and protective layers according to claim 1, characterized in that, After forming the second pre-cut line, the following is also included: Remove the waste edges from the protective layer; The protective layer, the adhesive, and the battery cell are split to form multiple small battery cells.

10. A bonding system for flexible module solar cells and a protective layer, characterized in that, The bonding system is applied to the bonding method of flexible module solar cells and protective layers as described in any one of claims 1 to 9, and the bonding system comprises: A pre-cutting device for pre-cutting the surface of the battery cell to form a first pre-cutting line and pre-cutting the surface of the protective layer to form a second pre-cutting line; A bonding device is used to bond the battery cell and the protective layer together with adhesive and then cure the adhesive. Alignment device, which assists the pre-cutting device in aligning the first pre-cutting line.

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