A BC battery front plate and a BC battery

Abstract

This application relates to a BC battery front panel and a BC battery. The BC battery front panel, along the direction away from the BC battery cell, sequentially includes: an interface bonding layer, a main support layer, and a nano-antireflective layer. The interface bonding layer is a silane coupling agent modified coating, the main support layer is made of fully tempered glass, and the nano-antireflective layer is a composite modified coating of nano-silica and titanium dioxide. The BC battery front panel of this application achieves simultaneous improvements in light transmittance, mechanical protection, outdoor weather resistance, and process adaptability.

Description

Technical Field

[0001] This application relates to the field of BC battery manufacturing, and more specifically, to a BC battery front panel and a BC battery. Background Technology

[0002] As a core technology for the high-efficiency and high-end development of the photovoltaic industry, BC cells have the core advantage of integrating all positive and negative electrodes on the back of the cell, with no grid lines obstructing the front. This fundamentally eliminates the light absorption loss caused by the grid lines on the front of traditional photovoltaic cells. At the same time, they have the characteristics of neat appearance, high bifaciality (up to 80% or more), and strong power generation stability. They have become the core direction for large-scale mass production, with current mass production efficiency exceeding 26% and laboratory efficiency approaching 28%.

[0003] In the manufacturing process of BC (Browser-Based Cell) batteries, the front panel, as the core packaging component at the front end of the BC battery, directly determines the battery's utilization rate of sunlight, outdoor environmental adaptability, and long-term operational reliability. It is a key component that matches the high power and high bifaciality advantages of BC batteries. Currently, the industry still uses modified solutions for traditional photovoltaic module front panels for BC batteries. These designs are not specifically tailored to the structural characteristics of BC batteries, such as the absence of grid lines on the front, higher light transmittance requirements, and the delicate and easily damaged back electrodes. This makes it difficult to meet the core needs of large-scale mass production and multi-scenario applications of BC batteries, specifically exhibiting the following technical shortcomings: 1. Insufficient adaptability of light transmission efficiency: Traditional front panels mostly adopt a single anti-reflection coating design, which has a high surface reflection loss and cannot fully release the structural potential of zero shading on the front of the BC cell. In particular, it is difficult to match the high light-receiving area requirement of 0BB gridless BC cells, which restricts further breakthroughs in the photoelectric conversion efficiency of the module. At the same time, some front panels use glass substrates with high iron content, which has a large absorption loss of the effective photovoltaic spectrum, further reducing the light utilization rate.

[0004] 2. Weak outdoor weather resistance: BC cells are exposed to outdoor ultraviolet radiation, alternating high and low temperatures (-40℃~85℃) and humid and hot environments for a long time. The traditional front panel surface is prone to aging phenomena such as yellowing, fogging and cracking, which leads to a gradual decrease in light transmittance. At the same time, its anti-fouling and anti-corrosion capabilities are insufficient, and it is easy to accumulate dust and attach pollutants, which further affects the power generation efficiency and shortens the service life of the module (the service life of BC modules adapted to traditional front panels is difficult to reach the 30-year design standard).

[0005] 3. Difficulty in balancing lightweight and mechanical strength: The front panel of the traditional double-glass encapsulation solution uses tempered glass of conventional thickness, which is relatively heavy (about 12.33kg / m²), increasing the load-bearing pressure on the roof and the on-site installation cost. It is especially unsuitable for load-bearing sensitive scenarios such as BIPV and distributed roofs. On the other hand, conventional ultra-thin glass front panels have insufficient impact resistance and microcrack resistance, and are easily damaged during production, transportation and installation, reducing the mass production yield.

[0006] 4. Poor process and interface compatibility: The interface bonding stability between the traditional front panel and the passivation layer (SiNx / SiO2 stack) on the front of the BC battery is insufficient, and defects such as gaps and delamination are easily generated during the encapsulation process. At the same time, it is difficult to adapt to mainstream preparation processes such as chain hydrofluoric acid treatment and alkaline texturing of BC batteries, which can easily cause damage to the front surface of the battery and affect battery performance. In addition, the compatibility between the traditional front panel and the encapsulation film is poor, and the problem of the film peeling off from the front panel after aging is easy to occur.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] The primary objective of this application is to provide a BC battery front panel specifically designed for use in BC batteries. This front panel achieves simultaneous improvements in light transmittance, mechanical protection, outdoor weather resistance, and process adaptability through an innovative multi-layer functional composite structure design. It fully leverages the core advantages of BC batteries, such as zero shading on the front and high bifaciality, while reducing the overall weight and installation cost of the module, improving mass production yield, extending the outdoor service life of the battery itself, and adapting to the technological development needs of new BC batteries such as silver-free and OBB.

[0009] The second objective of this application is to provide a BC battery that includes the aforementioned BC battery front panel. By adopting the front panel designed in this invention, the BC battery can better iterate towards silver-free, high bifaciality, and lightweight, which is of great practical significance for promoting the industrialization of BC battery technology and enhancing the core competitiveness of the industry.

[0010] To achieve the above objectives, in a first aspect, the present invention provides a BC battery front panel, which includes, in sequence along the direction away from the BC battery cell: an interface bonding layer, a main bearing layer, and a nano-antireflective layer; The interface bonding layer is a silane coupling agent modified coating, the main bearing layer is made of fully tempered glass, and the nano-antireflective layer is a composite modified coating of nano-silica and titanium dioxide.

[0011] The functional layers of the BC battery front panel of this invention are integrally formed using a low-temperature hot-pressing composite process. The molding temperature is controlled at 120-150℃, which avoids damage to the performance of each layer caused by high-temperature processing. Furthermore, the peel strength between adjacent layers is not less than 1.5N / mm, ensuring the overall structural stability of the front panel and meeting the requirements for large-scale packaging of BC batteries. Through the cooperation of the interface bonding layer, the main bearing layer, and the nano-antireflective layer, the mechanical properties such as increased light transmittance and strong bearing capacity are improved, while also enhancing the stability of the battery throughout the entire production process.

[0012] In an optional embodiment, the thickness of the nano-antireflective layer is 5-15 μm, wherein the mass ratio of silicon dioxide to titanium dioxide is (3-5):1.

[0013] Furthermore, the surface of the nano-antireflective layer is uniformly distributed with multiple protrusions, each protrusion having a width of 200-800 nm and a height of 100-500 nm.

[0014] The surface of the nano-antireflection layer is prepared by nanoimprint molding process to create an array structure of micro-nano-level protrusions, which can effectively reduce the surface reflection loss of sunlight and improve the utilization rate of incident light at different angles. It can meet the high light transmittance requirements of BC cells, and is especially suitable for the full surface light-receiving characteristics of 0BB gridless BC cells.

[0015] Furthermore, in the nano-antireflection layer, the mass ratio of nano-silica to titanium dioxide is controlled at (3-5):1. This ratio enables high-efficiency transmission of the photovoltaic effective spectrum (300-1100nm). Titanium dioxide can enhance the filtering effect of ultraviolet light, preventing ultraviolet light from damaging the passivation layer of the BC cell. The height of the micro-nano-level protrusions on the surface is 100-500nm and the width is 200-800nm. They are prepared by nanoimprint molding process. The reflection loss can be minimized by canceling multiple reflections of light, so that the light transmittance of the front panel in the 300-1100nm band reaches 93% or more, which fully matches the high light transmittance requirements of BC cells and improves the light transmittance by 2%-3% compared with traditional front panels.

[0016] Preferably, as a further feasible option, the thickness of the interface bonding layer is 1-5 μm.

[0017] The interface bonding layer serves to improve the stability of the interface bonding between the front panel and the passivation layer on the front of the BC battery, reduce interface defects generated during the packaging process, improve the adaptability of the front panel to the BC battery manufacturing process, reduce the risk of surface damage during production, and improve the mass production yield.

[0018] Furthermore, the interface bonding layer adopts a γ-aminopropyltriethoxysilane (KH550) modified coating, and its surface is treated with corona, which can improve the interfacial bonding force with the passivation layer (SiNx / SiO2 stack) on the front side of the BC battery, making the interfacial peel strength ≥2.0N / mm. At the same time, it can improve the compatibility with the encapsulation film and avoid the film delamination phenomenon after encapsulation. In addition, the interface bonding layer also has a certain acid resistance, which can be adapted to the BC battery chain hydrofluoric acid treatment process to avoid corrosion of the front panel surface.

[0019] Preferably, as a further feasible option, the thickness of the main bearing layer is 2.0-2.8 mm.

[0020] The main load-bearing layer provides stable mechanical support for the front panel, taking into account both lightweight requirements and impact resistance and microcrack resistance. It is compatible with the BC battery module single-glass encapsulation scheme, which can reduce the overall weight of the module by 15%-20% compared with the traditional double-glass encapsulation scheme (the weight of the single-glass module can be reduced to below 9.63kg / m²), significantly reducing the roof load-bearing pressure and installation costs.

[0021] Furthermore, the main load-bearing layer is made of low-iron ultra-clear tempered glass with an iron content controlled below 0.015wt% and a light transmittance of no less than 91%. It also has a bending strength of ≥150MPa and an impact strength of ≥4J, and can withstand the impact of 45mm hail. The reason for choosing this type of tempered glass material is to ensure the mechanical reliability of the front panel while meeting the requirements of lightweight design. When adapted to a single-glass tempered glass encapsulation scheme, it is paired with a double-beam alloy steel frame, which can make the BC battery's wind and snow load resistance performance 50% higher than that of the traditional aluminum frame, further improving the battery's outdoor operation stability.

[0022] Preferably, as a further feasible option, a buffer stress layer is further provided between the interface bonding layer and the main bearing layer, wherein the buffer stress layer is a modified EVA composite film with a thickness of 20-40μm.

[0023] The function of the buffer stress layer is to alleviate the stress impact during the subsequent packaging and use of the battery, to prevent the main bearing layer from being damaged due to thermal expansion and contraction or external force, and at the same time to improve the tightness of the bonding between the layers and reduce the light reflection loss caused by the gaps between the layers.

[0024] Specifically, the buffer stress layer uses a composite modified film of ethylene-vinyl acetate copolymer (EVA) and polyolefin elastomer (POE), with POE content accounting for 30%-50%. This can improve the aging resistance of the buffer stress layer and its adhesion to the main bearing layer and interface bonding layer. At the same time, it has excellent high and low temperature resistance, and does not become brittle or deformed in the range of -40℃ to 85℃, avoiding front plate damage or interlayer delamination caused by stress due to temperature changes.

[0025] Preferably, as a further feasible option, a weather-resistant and anti-fouling layer is further provided on the outer side of the nano-antireflective layer. The weather-resistant and anti-fouling layer is a UV-resistant fluorinated polymer film with a thickness controlled at 10-30 μm.

[0026] Preferably, as a further feasible option, an ultraviolet absorber of benzotriazole or benzophenone compounds is added to the weather-resistant and anti-fouling layer.

[0027] The weather-resistant and anti-fouling layer serves to resist outdoor ultraviolet radiation, mitigate the aging effects of high and low temperatures and humid environments on the front panel, and improve the anti-fouling and anti-corrosion performance of the front panel surface. It is suitable for complex outdoor application scenarios, especially meeting the usage needs of extreme scenarios such as coastal high salt spray and desert high dust.

[0028] Furthermore, the weather-resistant and anti-fouling layer preferentially uses polyvinylidene fluoride (PVF) or polyvinylidene fluoride (PVDF) film. Its surface is plasma-activated to achieve a surface tension of 38mN / m or higher, which significantly improves the adhesion to the nano-antireflective layer and avoids delamination. At the same time, 0.5-2.0wt% of benzotriazole or benzophenone compounds are added to the weather-resistant and anti-fouling layer as ultraviolet absorbers, which can efficiently absorb ultraviolet rays in the 280-400nm wavelength band, slow down the aging rate of the front panel, and ensure the stability of the battery during long-term outdoor operation (more than 30 years). It can also improve the hydrophobicity of the front panel surface, with a contact angle ≥90°, achieving a self-cleaning effect and reducing dust adhesion.

[0029] Secondly, the present invention also provides a BC battery, including the aforementioned BC battery front panel, BC battery cells, encapsulation film, back panel, and frame.

[0030] The BC cell adopts a grid-free structure on the front, with a passivation layer on the front and interdigitated positive and negative electrodes on the back. The front panel of the BC cell is bonded to the front of the BC cell through an encapsulating film, and the back panel is bonded to the back of the BC cell through an encapsulating film. The frame wraps around the entire structure to form a complete BC cell.

[0031] Preferably, as a further feasible option, the encapsulating film is an acid-resistant POE film with a thickness of 0.3-0.5 mm. This is compatible with the silver-free process of BC batteries (silver-clad copper electrodes), preventing chemical reactions between the film and the electrode, while also possessing excellent aging resistance and encapsulation stability.

[0032] Preferably, as a further feasible option, the backsheet is a weather-resistant fluorocarbon backsheet with a thickness of 100-150μm, which has excellent waterproof and corrosion-resistant properties and works in conjunction with the front sheet to achieve all-round protection for the BC solar cells.

[0033] The manufacturing process of BC batteries is compatible with the existing mass production process of BC batteries and does not require additional special equipment. The specific steps include: front panel pretreatment → encapsulation film laying → BC cell layout → encapsulation film laying → back panel laying → lamination → frame installation → testing and packaging. The lamination temperature is controlled at 140-160℃ and the pressure is controlled at 0.1-0.3MPa to ensure that each layer is tightly bonded and free of bubbles and delamination defects.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention achieves simultaneous improvement in light transmittance, mechanical protection, outdoor weather resistance and process adaptability by innovatively designing a multi-layer functional composite structure for the front panel of the battery.

[0035] (2) The BC battery of the present invention, by adopting the front plate designed by the present invention, enables the BC battery to better iterate towards silver-free, high bifaciality and lightweight, which has important practical significance for promoting the industrialization of BC battery technology and enhancing the core competitiveness of the industry.

[0036] (3) The battery manufacturing process of the present invention is simple, the operating cost is low, the production efficiency is improved, and large-scale application is realized.

[0037] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, 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 this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the layered structure of the BC battery front panel provided by the present invention; Figure 2 This is an enlarged schematic diagram of the micro / nano structure on the surface of the nano-antireflective layer provided by the present invention; Figure 3 A schematic diagram of the overall structure of a BC battery using the aforementioned battery front panel provided by the present invention; Figure 4 This is a schematic diagram of the back electrode structure of the BC battery cell provided by the present invention.

[0040] icon: 1-Weather-resistant and anti-fouling layer; 2-Nano-antireflective layer; 3-Main load-bearing layer; 4-Strength buffer layer; 5-Interface bonding layer; 6-Protrusion; 7-BC battery front panel; 8-BC battery cell; 9-Encapsulation film; 10-Back panel; 11-Frame; 12-Passivation layer; 13-Front side; 14-Back side; 15-Positive electrode; 16-Negative electrode. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0042] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] Example 1 See Figure 1 In terms of structure, the BC battery front panel of this embodiment includes, in sequence along the direction away from the BC battery cell: a weather-resistant and anti-fouling layer 1, a nano-antireflective layer 2, a main bearing layer 3, a buffer stress layer 4, and an interface bonding layer 5. Each functional layer is integrally formed by a low-temperature hot-pressing composite process with a molding temperature of 130°C and a peel strength between adjacent layers of 1.8 N / mm. Figure 1 The front panel of the BC battery is drawn vertically, clearly showing the arrangement of each functional layer. The thickness of each layer is drawn proportionally, and the bonding surfaces between adjacent layers are marked with straight lines, intuitively reflecting the integrated composite structure. Among them, the weather-resistant and anti-fouling layer 1 is the outermost layer, which is in direct contact with the external environment, and the interface bonding layer 5 is the innermost layer, which is used to bond with the front side 13 of the BC battery cell 8.

[0045] Among them, the weather-resistant and anti-fouling layer 1 is made of PVDF film with a thickness of 20μm. The surface is plasma activated and has a surface tension of 40mN / m. 1.2wt% of benzotriazole UV absorber is added and the surface has a hydrophobic contact angle of 95°, which has excellent UV resistance and anti-fouling performance.

[0046] The nano-antireflective layer 2 is a composite modified coating of nano-silica and titanium dioxide in a mass ratio of 4:1, with a thickness of 10 μm. The surface is formed using a nano-imprinting process, and multiple protrusions 6 are uniformly distributed on the surface, with a height of 300 nm and a width of 500 nm. The light transmittance of the front panel in the 300-1100 nm wavelength range is 93.5%. A magnified schematic diagram of the nano-antireflective layer 2 is shown below. Figure 2 As shown in the figure, the arrangement of the micro-nano protrusions 6 is clearly displayed. They are evenly distributed, and the curved lines in the figure depict the concave and convex contours, intuitively demonstrating their structural characteristics for reducing light reflection.

[0047] The main load-bearing layer 3 is made of low-iron ultra-clear tempered glass with an iron content of 0.012wt%, a thickness of 2.5mm, a light transmittance of 91.5%, a bending strength of 160MPa, an impact strength of 4.5J, and can withstand the impact of 45mm hail, meeting the requirements of lightweight and mechanical strength.

[0048] The buffer stress layer 4 is made of EVA and POE composite modified film with 40% POE content and a thickness of 30μm. It does not become brittle or deform within the range of -40℃ to 85℃ and has excellent buffer stress performance.

[0049] The interface bonding layer 5 is a KH550 silane coupling agent modified coating with a thickness of 3μm and a surface treated with corona. The interface peel strength with the passivation layer on the front of the BC battery is 2.2N / mm, which is compatible with the BC battery chain hydrofluoric acid treatment process.

[0050] Then, the front panel prepared above is used for battery assembly. Other components required for battery assembly include BC battery cells, encapsulating film, backplate, and frame. A schematic diagram of the overall structure of the BC battery is shown below. Figure 3As shown, it demonstrates the complete structure of the BC battery. From the outside to the inside, it consists of the BC battery front panel 7, encapsulation film 9, BC battery cell 8, encapsulation film 9, and back panel 10. The frame 11 wraps around the entire structure, forming a closed protective structure. The front 13 of the BC battery cell 8 faces the BC battery front panel 7, and the back 14 faces the back panel 10, which intuitively shows the assembly relationship of each component. The specific assembly process of the BC battery is as follows: the BC battery cell 8 adopts an OBB gridless structure. The front 13 is provided with a SiNx / SiO2 stacked passivation layer 12, and the back 14 is provided with interdigitated positive electrodes 15 and negative electrodes 16 (silver-clad copper material). The BC battery front panel 7 is bonded to the front 13 of the BC battery cell 8 through the encapsulation film 9, and the back panel 10 is bonded to the back 14 of the BC battery cell 8 through the encapsulation film 9. The frame 11 is a double-beam alloy steel frame that wraps around the entire structure. The encapsulation film 9 is made of acid-resistant POE film with a thickness of 0.4mm, and the backsheet 10 is made of weather-resistant fluorocarbon backsheet with a thickness of 120μm. The overall weight of the module is 9.5kg / m², which is 18% lighter than traditional double-glass modules. The photoelectric conversion efficiency of the assembled cells is 25.2%. After UV 120kWh aging test, the efficiency degradation is ≤1.5%. After 3000 hours of damp heat test, there is no delamination or aging phenomenon, making it suitable for rooftop distributed photovoltaic scenarios.

[0051] also, Figure 4 This is a top view of the back side 14 of the BC battery cell 8, drawn horizontally. It clearly shows the interdigitated electrode structure of the back side 14. The positive electrode 15 and the negative electrode 16 are arranged in a cross pattern without overlapping areas, which intuitively reflects the core structural feature of the BC battery: "no grid lines on the front and integrated electrodes on the back". The connection relationship between the electrodes and the battery cell is also marked to facilitate understanding of the adaptation logic between the BC battery and the front panel.

[0052] Example 2 The front panel of the BC battery in this embodiment of the invention, in terms of structure, includes the following components in sequence along the direction away from the BC battery cell: a weather-resistant and anti-fouling layer 1, a nano-antireflective layer 2, a main bearing layer 3, a buffer stress layer 4, and an interface bonding layer 5. Each functional layer is integrally formed by a low-temperature hot-pressing composite process with a molding temperature of 120°C and a peel strength of 1.7 N / mm between adjacent layers.

[0053] Among them, the weather-resistant and anti-fouling layer 1 is made of PVDF film with a thickness of 10μm. The surface is treated with plasma activation, with a surface tension of 40mN / m. 2wt% of benzotriazole UV absorber is added, and the surface has a hydrophobic contact angle of 95°, which has excellent UV resistance and anti-fouling properties.

[0054] The nano-antireflective layer 2 is a composite modified coating of nano-silica and titanium dioxide with a mass ratio of 5:1 and a thickness of 15μm. The surface is formed using a nano-imprinting process, with multiple uniformly distributed protrusions 6, each 500nm high and 200nm wide. The light transmittance of the front panel in the 300-1100nm wavelength range is 93.2%. A magnified schematic diagram of the nano-antireflective layer 2 is shown below. Figure 2 As shown in the figure, the arrangement of the micro-nano protrusions 6 is clearly displayed. They are evenly distributed, and the curved lines in the figure depict the concave and convex contours, intuitively demonstrating their structural characteristics for reducing light reflection.

[0055] The main load-bearing layer 3 is made of low-iron ultra-clear tempered glass with an iron content of 0.011wt%, a thickness of 2.0mm, a light transmittance of 91.3%, a bending strength of 155MPa, an impact strength of 4.6J, and can withstand the impact of 45mm hail, meeting the requirements of lightweight and mechanical strength.

[0056] The buffer stress layer 4 is made of EVA and POE composite modified film with 30% POE content and a thickness of 20μm. It does not become brittle or deform within the range of -40℃ to 85℃ and has excellent buffer stress performance.

[0057] The interface bonding layer 5 is a KH550 silane coupling agent modified coating with a thickness of 5 μm and a corona-treated surface. Its interface peel strength with the passivation layer on the front side of the BC battery is 2.3 N / mm, making it compatible with the BC battery's chain-type hydrofluoric acid treatment process. The subsequent assembly method for the BC battery is consistent with Example 1.

[0058] Example 3 The front panel of the BC battery in this embodiment of the invention, in terms of structure, includes the following components in sequence along the direction away from the BC battery cell: a weather-resistant and anti-fouling layer 1, a nano-antireflective layer 2, a main bearing layer 3, a buffer stress layer 4, and an interface bonding layer 5. Each functional layer is integrally formed by a low-temperature hot-pressing composite process with a molding temperature of 150°C and a peel strength of 1.8 N / mm between adjacent layers.

[0059] Among them, the weather-resistant and anti-fouling layer 1 is made of PVDF film with a thickness of 30μm. The surface is plasma activated and has a surface tension of 40mN / m. It contains 0.5wt% benzophenone-based ultraviolet absorber and has a hydrophobic contact angle of 95°, which gives it excellent UV resistance and anti-fouling properties.

[0060] The nano-antireflective layer 2 is a composite modified coating of nano-silica and titanium dioxide in a mass ratio of 3:1, with a thickness of 5μm. The surface is formed using a nano-imprinting process, and multiple protrusions 6 are uniformly distributed on the surface, with a height of 100nm and a width of 800nm. The light transmittance of the front panel in the 300-1100nm wavelength range is 93.3%. A magnified schematic diagram of the nano-antireflective layer 2 is shown below. Figure 2 As shown in the figure, the arrangement of the micro-nano protrusions 6 is clearly displayed. They are evenly distributed, and the curved lines in the figure depict the concave and convex contours, intuitively demonstrating their structural characteristics for reducing light reflection.

[0061] The main load-bearing layer 3 is made of low-iron ultra-clear tempered glass with an iron content of 0.010wt%, a thickness of 2.8mm, a light transmittance of 91.2%, a bending strength of 165MPa, an impact strength of 4.4J, and can withstand the impact of 45mm hail, meeting the requirements of lightweight and mechanical strength.

[0062] The buffer stress layer 4 is made of EVA and POE composite modified film with 50% POE content and a thickness of 40μm. It does not become brittle or deform within the range of -40℃ to 85℃ and has excellent buffer stress performance.

[0063] The interface bonding layer 5 is a KH550 silane coupling agent modified coating with a thickness of 1 μm and a corona-treated surface. Its interface peel strength with the passivation layer on the front side of the BC battery is 2.1 N / mm, making it compatible with the BC battery's chain-type hydrofluoric acid treatment process. The subsequent assembly method for the BC battery is consistent with Example 1.

[0064] In summary, the BC battery of the present invention has the following significant advantages compared with the prior art, all of which are based on actual mass production test data and are in line with the actual needs of the industry: 1. Significantly improved light transmittance: Through the composite modification design of the nano-antireflective layer and the optimization of the micro-nano-level protrusion structure, combined with the low-iron ultra-white main support layer, the light transmittance of the front panel in the effective photovoltaic spectrum range reaches 93% or more, which is 2%-3% higher than that of traditional front panels. This can fully release the structural advantage of zero shading on the front of the BC cell, helping to improve the photoelectric conversion efficiency of the module by 1%-1.5%. It is especially suitable for the high light reception requirements of 0BB gridless BC cells, further amplifying the efficiency advantage of BC cells.

[0065] 2. Significantly enhanced outdoor weather resistance: The fluorinated film design of the weather-resistant and anti-fouling layer, combined with the addition of UV absorbers, can effectively resist the effects of UV erosion, alternating high and low temperatures, and humid and hot environments. After a UV 120kWh aging test, the light transmittance decreases by ≤2%. After 3000 hours of humid heat and 4000 hours of salt spray tests, there are no obvious signs of aging or corrosion. This ensures that the outdoor service life of the module reaches more than 30 years, significantly reducing the later maintenance costs of the module.

[0066] 3. Synergistic optimization of lightweight and mechanical strength: Using 2.0-2.8mm ultra-thin high-strength fully tempered glass as the main load-bearing layer, combined with a single-glass encapsulation scheme, the overall weight of the battery is reduced by 15%-20% compared to traditional double-glass encapsulation, alleviating the load-bearing pressure on the roof and reducing installation costs. At the same time, it has excellent impact resistance and microcrack resistance, can withstand 45mm hail impact, and has no microcracks in the 8000Pa static load test, improving the breakage rate during production, transportation and installation, and increasing the mass production yield to over 97%.

[0067] 4. Strong process adaptability and high feasibility for mass production: The modified design of the silane coupling agent in the interface bonding layer improves the stability of the interface bonding with the passivation layer on the front side of the BC cell. At the same time, it is compatible with mainstream preparation processes such as chain hydrofluoric acid treatment and alkaline texturing of BC cells, avoiding damage to the cell surface. Each layer adopts a low-temperature hot-pressing composite process, which is compatible with existing photovoltaic module production equipment. No new special equipment is required, reducing the technical transformation cost of enterprises and facilitating large-scale mass production. It can also be adapted to silver-free (silver-clad copper) BC cells, helping to reduce module costs and increase efficiency.

[0068] 5. Excellent adaptability to multiple scenarios: The lightweight design is suitable for load-bearing sensitive scenarios such as BIPV building integration and rooftop distributed systems; the strong protective performance is suitable for extreme outdoor scenarios such as coastal high salt spray and desert high dust; and the high light transmittance performance is suitable for scenarios with high power generation efficiency requirements such as centralized ground power stations. It can realize the full coverage of BC battery applications in multiple scenarios and enhance the product's market competitiveness.

[0069] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0070] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A BC battery front panel, characterized in that, Along the direction away from the BC solar cell, the following are sequentially included: interface bonding layer, main support layer, and nano-antireflective layer; The interface bonding layer is a silane coupling agent modified coating, the main bearing layer is made of fully tempered glass, and the nano-antireflective layer is a composite modified coating of nano-silica and titanium dioxide.

2. The BC battery front panel according to claim 1, characterized in that, The thickness of the nano-antireflective layer is 5-15 μm, wherein the mass ratio of silicon dioxide to titanium dioxide is (3-5):

1.

3. The BC battery front panel according to claim 1, characterized in that, The surface of the nano-antireflective layer has multiple protrusions evenly distributed, each protrusion having a width of 200-800 nm and a height of 100-500 nm.

4. The BC battery front panel according to claim 1, characterized in that, The thickness of the interface bonding layer is 1-5 μm.

5. The BC battery front panel according to claim 1, characterized in that, The thickness of the main bearing layer is 2.0-2.8 mm.

6. The BC battery front panel according to any one of claims 1-5, characterized in that, A buffer stress layer is provided between the interface bonding layer and the main bearing layer. The buffer stress layer is a modified EVA composite film with a thickness of 20-40μm.

7. The BC battery front panel according to any one of claims 1-5, characterized in that, The outer side of the nano-antireflective layer is provided with a weather-resistant and anti-fouling layer, which is a UV-resistant fluorinated polymer film with a thickness controlled between 10-30 μm.

8. The BC battery front panel according to claim 7, characterized in that, The weather-resistant and anti-fouling layer contains ultraviolet absorbers made of benzotriazole or benzophenone compounds.

9. A BC battery, characterized in that, It includes the BC battery front panel, BC battery cell, encapsulation film, back panel and frame as described in any one of claims 1-8.

10. The BC battery according to claim 9, characterized in that, The encapsulating film is an acid-resistant POE film with a thickness of 0.3-0.5 mm.

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