Front side protection layer structure for back contact cells

Abstract

The utility model relates to the field of back contact battery discloses a front protection layer structure of back contact battery, wherein, transparent protection glue layer sets up on the light receiving surface of battery main part. Protection glue layer is discontinuous linear distribution. The coverage area of protection glue layer on the light receiving surface of battery main part is 1% 10%. The total length L3 of glue layer line segment is 30~3000mu m. The glue layer line segment includes wide area and intermediate narrow area. Wide area is located at both ends of glue layer line segment, and narrow area is located at the middle of both end wide areas, and the width of narrow area to wide area gradually increases. The length L1 of narrow area is 10~1000mu m, and the width W1 is 10~500mu m. The length L2 of wide area is 2 5 times of narrow area length L1, and the width W2 of wide area end is 1.1 5 times of narrow area width W1. The utility model discloses the widening design of protection layer pattern both ends makes the printing pattern edge more regular and straight, improves the stress uniformity. In addition, this kind of pattern design can adapt to high speed printing, effectively promotes the printing speed, improves the production capacity.

Description

Technical Field

[0001] This utility model relates to the field of back contact batteries, and in particular to a front protective layer structure for a back contact battery. Background Technology

[0002] Because the front side of the back-contact battery lacks grid lines for shielding, the SiN layer on its surface is easily damaged by mutual friction during stacking. Currently, the industry commonly uses separator paper as a protective measure, but this solution has problems such as short cycle life and high cost, making it difficult to meet the needs of large-scale production.

[0003] In existing technologies, two methods are typically used to reduce the risk of scratches on the front of the back contact battery: one is to print a protective layer on the entire front surface; the other is to print a protective layer pattern in the shape of continuous straight lines, dots, or dashed lines.

[0004] In existing technologies, when using printed thermosetting or photocurable resin polymer materials as the front protective layer of a battery, the following specific problems exist:

[0005] I. The contradiction between the protected area and the amount of materials used:

[0006] 1. When a solution with a large protective area is adopted, such as printing a protective layer on the entire front of the battery cell or printing continuous straight lines, it will result in a large amount of protective layer material and an increased light-blocking area, thereby reducing battery efficiency.

[0007] 2. If the protected area is reduced, for example by printing a dotted protective layer pattern, the protective effect is not ideal.

[0008] II. Limitations of graphic design and printing effects:

[0009] If the printed protective layer pattern is a dotted line using a conventional uniform-width strip design, the protective layer material will flow unevenly under the pressure of the squeegee, overflowing from the center of the pattern to both vertical sides. This results in a poor overall shape, inconsistent height, uneven stress, and ineffective protection of the battery cells. Ultimately, this leads to scratches on the battery cell surface and affects battery efficiency. Specific manifestations are as follows:

[0010] 1. Poor graphic appearance: During the printing process, the protective layer material tends to overflow from the center of the graphic to the vertical sides under the pressure of the squeegee, resulting in an irregular appearance and rough edges after printing, and an inability to form a uniform protective layer.

[0011] 2. Inconsistent height: The colloid distribution exhibits a shape that is high in the middle and low at both ends, forming a "peak-shaped" structure in cross-section. This results in a height difference of up to 5μm in the colloid layer, causing localized stress concentration and increasing the risk of film damage.

[0012] 3. Uneven stress: Due to uneven height and morphological defects, the film layer of the solar cells is prone to scratches and damage during stacking and transportation due to uneven stress.

[0013] III. Production Capacity Limitations:

[0014] Using printing technology with graphic designs featuring uniformly wide line segments presents certain limitations. Due to the limited opening of the printing screen, the amount of adhesive tends to accumulate in the middle and decrease at the ends during printing. Therefore, it cannot be adapted to high-speed printing (≥300mm / s), impacting production capacity. Utility Model Content

[0015] The purpose of this invention is to solve the problems of high cost, poor battery efficiency, large differences in overall shape and height, and production capacity limitation in the existing technology. It provides a front protective layer structure for back contact batteries, which makes the edges of printed graphics more regular and straight, improves the uniformity of force, and can also adapt to high-speed printing, effectively improving printing speed and increasing production capacity.

[0016] To achieve the above objectives, the present invention adopts the following technical solution:

[0017] This utility model discloses a front protective layer structure for a back contact battery, comprising a back contact battery body and a transparent protective adhesive layer. The transparent protective adhesive layer is disposed on the light-receiving surface of the battery body. The protective adhesive layer is distributed in a discontinuous linear shape, composed of several adhesive layer segments, with the extension direction parallel to the extension direction of the back grid lines; the coverage area of ​​the protective adhesive layer on the light-receiving surface of the battery body is 1%-10%; the total length L3 of the adhesive layer segments is 30~3000μm; each adhesive layer segment includes a wide area and a narrow area in the middle, the wide area is located at both ends of the adhesive layer segment, and the narrow area is located in the middle of the two wide areas, the width of the narrow area gradually increases from the wide area; the length L1 of the narrow area is 10~1000μm, and the width W1 is 10~500μm; the length L2 of the wide area is 2-5 times the length L1 of the narrow area, and the width W2 at the end of the wide area is 1.1-5 times the width W1 of the narrow area.

[0018] Furthermore, the wide area is in the shape of an isosceles trapezoidal pile, and the narrow area is in the shape of a rectangle.

[0019] Furthermore, the protective adhesive layer is a UV adhesive layer based on a polyacrylate system.

[0020] Furthermore, a transparent elastomer adhesive layer is disposed above the UV adhesive layer. The material of the transparent elastomer adhesive layer can be: silicone-modified acrylate, aliphatic polyurethane elastomer, or silicone elastomer.

[0021] Furthermore, the thickness H of the protective adhesive layer is 5-100μm, the distance L4 between adjacent upper and lower protective adhesive layers is 5-20mm, and the distance L5 between adjacent left and right adhesive layer segments is 1-5mm.

[0022] The advantages of this utility model are:

[0023] 1. Optimize printing morphology and height uniformity: Widen the two ends and adopt a gradient design to make the edges of the graphic more regular and straight, improving morphological defects. At the same time, the height difference of the adhesive layer is controlled within 2μm, which is reduced compared to 5μm in the existing technology. The protective layer is subjected to uniform stress when facing various external forces, enhancing the protective effect on the battery film layer.

[0024] 2. Increased stress-bearing area and improved uneven stress distribution: By widening the ends of the protective layer pattern, the stress-bearing area is increased by approximately 20% compared to the traditional uniform-width strip structure. When the solar cell is subjected to external force, the stress is more evenly distributed, thereby reducing the risk of scratches and damage to the film layer caused by uneven stress and improving the mechanical reliability of the solar cell.

[0025] 3. Balancing Protection Area and Material Usage: This invention optimizes the protective layer's graphic design, avoiding material waste and light-blocking issues caused by large-area protective layers, while simultaneously solving the problem of poor protection effects with small areas. It meets the protection requirements of the battery cells while minimizing light-blocking area, effectively improving battery efficiency.

[0026] 4. High-speed printing compatibility: By optimizing the protective layer graphic design, the problem of uneven glue distribution caused by the screen opening limitation in the existing technology has been solved. This design can adapt to high-speed printing (printing speed ≥300mm / s), significantly improving production capacity and meeting the needs of large-scale production. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model 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.

[0028] Figure 1 This is a schematic diagram of the back contact battery in Examples 1-4.

[0029] Figure 2 This is a cross-sectional view of the back contact battery in Examples 1-4.

[0030] Figure 3 This is a top view (a) of the protective adhesive layer in Examples 1-4.

[0031] Figure 4 This is a top view (II) of the protective adhesive layer in Examples 1-4.

[0032] Figure 5 This is an interface diagram of the protective adhesive layer in Comparative Example 1 under a probe-type surface profilometer.

[0033] Figure 6 This is an interface diagram of the protective adhesive layer of Example 1 under a probe-type surface profilometer.

[0034] Explanation of key component symbols:

[0035] 1. Battery body;

[0036] 2. Protect the adhesive layer;

[0037] 3. Wide area;

[0038] 4. Narrow area;

[0039] 5. Transparent elastomer adhesive layer. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0041] In this utility model, 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.

[0042] 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 utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0043] In this utility model, 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 through an intermediate medium. Furthermore, "above," "on top of," and "over" 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.

[0044] 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).

[0045] Example 1:

[0046] like Figure 1 , Figure 2 As shown, this utility model discloses a front protective layer structure for a back contact battery, which includes a back contact battery body 1 and a transparent protective adhesive layer 2.

[0047] The transparent protective adhesive layer 2 is disposed on the light-receiving surface of the battery body 1. The protective adhesive layer 2 is distributed in a discontinuous linear shape, consisting of several adhesive layer segments, and its extension direction is parallel to the extension direction of the back grid lines.

[0048] like Figure 3 , Figure 4 As shown, the protective adhesive layer 2 covers 1%-10% of the light-receiving surface of the battery body 1. The total length L3 of the adhesive layer segments is 30~3000μm, the thickness H of the protective adhesive layer 2 is 5-100μm, the distance L4 between adjacent vertical protective adhesive layers 2 is 5-20mm, and the distance L5 between adjacent horizontal adhesive layer segments is 1-5mm.

[0049] The adhesive layer segment includes a wide section 3 and a narrow section 4 in the middle. The wide section 3 is located at both ends of the adhesive layer segment, and the narrow section 4 is located in the middle of the two wide sections 3. The width of the narrow section 4 gradually increases from the width of the wide section 3. Specifically, the wide section 3 is an isosceles trapezoidal pile, and the narrow section 4 is rectangular.

[0050] The length L1 of narrow region 4 is 10~1000μm, and the width W1 is 10~500μm. The length L2 of wide region 3 is 2-5 times the length L1 of narrow region 4, and the width W2 at the end of wide region 3 is 1.1-5 times the width W1 of narrow region 4.

[0051] The protective adhesive layer 2 is a UV adhesive layer based on a polyacrylate system, with a transparent elastomer adhesive layer 5 placed on top of the UV adhesive layer. The transparent elastomer adhesive layer 5 can be made of silicone-modified acrylate, aliphatic polyurethane elastomer, or silicone elastomer. Utilizing the buffering properties of the elastomer, stress can be better dispersed, reducing the risk of film damage.

[0052] The protective adhesive layer 2 can also be made of composite materials. Combining two or more materials with different properties allows for the utilization of their strengths and compensates for their weaknesses. For example, combining polyacrylate with nanoparticles can improve the material's hardness and wear resistance.

[0053] In this embodiment, the width W1 of narrow region 4 is 100μm, the width W2 of wide region 3 is 1.4 times the width W1 of narrow region 4 (140μm), the length L1 of narrow region 4 is 150μm, the length L2 of wide region 3 is 2.2 times the length L1 of narrow region 4 (325μm), and the total length L2 of the adhesive layer segments is 2 * length L2 of wide region 3 + length L1 of narrow region 4 = 800μm. The distance L4 between adjacent vertical protective adhesive layers 2 is 10mm, and the distance L5 between adjacent horizontal adhesive layer segments is 2mm.

[0054] Example 2:

[0055] The width W1 of narrow region 4 is 100μm, the width W2 of wide region 3 is 2.8 times the width W1 of narrow region 4 (280μm), the length L1 of narrow region 4 is 150μm, the length L2 of wide region 3 is 2.2 times the length L1 of narrow region 4 (325μm), and the total length L2 of the adhesive layer segment is 2 * the length L2 of wide region 3 + the length L1 of narrow region 4 = 800μm.

[0056] Other features are consistent with those in Example 1.

[0057] Example 3:

[0058] The width W1 of narrow region 4 is 100μm, the width W2 of wide region 3 is 4 times the width W1 of narrow region 4 (400μm), the length L1 of narrow region 4 is 150μm, the length L2 of wide region 3 is 2.2 times the length L1 of narrow region 4 (325μm), and the total length L2 of the adhesive layer segment is 2 * the length L2 of wide region 3 + the length L1 of narrow region 4 = 800μm.

[0059] Other features are consistent with those in Example 1.

[0060] Example 4:

[0061] The width W1 of narrow region 4 is 200μm, the width W2 of wide region 3 is 1.4 times the width W1 of narrow region 4 (280μm), the length L1 of narrow region 4 is 200μm, the length L2 of wide region 3 is 3 times the length L1 of narrow region 4 (600μm), and the total length L2 of the adhesive layer segment is 2 * the length L2 of wide region 3 + the length L1 of narrow region 4 = 1400μm.

[0062] Other features are consistent with those in Example 1.

[0063] Comparative Example 1:

[0064] The width of the adhesive layer segments is equal, the width of narrow region 4 W1 = the width of wide region 3 W2 = 100μm, and the total length of the adhesive layer segments L2 = 800μm.

[0065] Other features are consistent with those in Example 1.

[0066] Comparative Example 2:

[0067] The width of the adhesive layer segments is constant. The width of narrow region 4, W1, is equal to the width of wide region 3, W2, which is 200 μm. The total length of the adhesive layer segments, L2, is 1400 μm.

[0068] Other features are consistent with those in Example 1.

[0069] Table 1 shows the protective layer structures of five battery cells from Examples 1 to 3 and Comparative Examples 1 and 2. The battery cells with the protective layer printed on the front were subjected to automated loading and unloading 10 times. The surface of the cells was observed under a microscope to check for scratches, and the efficiency was compared with that of the initial battery cells without a protective layer and without simulated transportation. The decrease in efficiency was calculated. Furthermore, the cross-sectional profiles of the protective layer patterns of the five battery cell structures from Examples 1 to 3 and Comparative Examples 1 and 2 were measured using a probe-type surface profilometer, and their height differences were compared.

[0070] As can be seen from the data in Table 1:

[0071] The height difference of the protective layer pattern of the battery cells in Examples 1 to 3 is much smaller than that in Comparative Examples 1 and 2, which makes the film layer more uniformly stressed during the stacking and transportation of the battery cells, reducing problems such as scratches and damage to the battery cells.

[0072] After simulating the production and transportation of the battery cells, the battery cells of Examples 1 to 3 showed no obvious scratches on their appearance. Compared with the existing comparative examples 1 and 2, this greatly improved the problem of scratches on the appearance of the battery cells. At the same time, in terms of battery efficiency, the loss was reduced from the original 0.078%-0.084% to 0.014%-0.019%, effectively improving battery efficiency.

[0073] The data comparison of Examples 1-3 shows that an increase in the W2 / W1 ratio is more conducive to reducing the height difference of the protective layer pattern and improving battery efficiency.

[0074]

[0075] Table 1. Comparison of parameter data for various scenarios after simulated battery cell production and transportation.

[0076] In summary, this invention, by widening the ends of the protective layer pattern, makes the edges of the printed pattern more regular and straight, improving the shape defect of being high in the middle and low at both ends. This increases the contact area between adjacent battery cells during stacking, improving the uniformity of stress distribution. Furthermore, this pattern design can adapt to high-speed printing, effectively increasing printing speed and production capacity.

[0077] The preferred embodiments of this utility model have been described in detail above; however, this utility model is not limited thereto. Within the scope of the technical concept of this utility model, various simple modifications can be made to the technical solution of this utility model, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed by this utility model and are all within the protection scope of this utility model.

Claims

1. A front protective layer structure for a back contact battery, comprising a back contact battery body and a transparent protective adhesive layer; the transparent protective adhesive layer is disposed on the light-receiving surface of the battery body; characterized in that: The protective adhesive layer is distributed in a discontinuous linear pattern, consisting of several adhesive layer segments, with the extension direction parallel to the extension direction of the back grid lines. The coverage area of ​​the protective adhesive layer on the light-receiving surface of the battery body is 1%-10%. The total length L3 of the adhesive layer segments is 30-3000μm. Each adhesive layer segment includes a wide region and a narrow region in the middle. The wide region is located at both ends of the adhesive layer segment, and the narrow region is located in the middle of the two wide regions. The width of the narrow region gradually increases from the wide region to the narrow region. The length L1 of the narrow region is 10-1000μm, and the width W1 is 10-500μm. The length L2 of the wide region is 2-5 times the length L1 of the narrow region, and the width W2 at the end of the wide region is 1.1-5 times the width W1 of the narrow region.

2. The front protective layer structure of the back contact battery according to claim 1, characterized in that: The wide area is in the shape of an isosceles trapezoid, and the narrow area is in the shape of a rectangle.

3. The front protective layer structure of the back contact battery according to claim 1, characterized in that: The protective adhesive layer is a UV adhesive layer based on a polyacrylate system.

4. The front protective layer structure of the back contact battery according to claim 3, characterized in that: A transparent elastomer adhesive layer is also provided on top of the UV adhesive layer.

5. The front protective layer structure of the back contact battery according to claim 1, characterized in that: The thickness H of the protective adhesive layer is 5-100μm, the distance L4 between adjacent upper and lower protective adhesive layers is 5-20mm, and the distance L5 between adjacent left and right adhesive layer segments is 1-5mm.

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