A battery assembly and a back contact battery

Abstract

This application relates to a battery module and a back-contact battery. The battery module includes: a battery cell body, several pads, a solder ribbon, and a protective adhesive layer. Several pads are disposed on one side surface of the battery cell body. Several soldering positions are provided on the solder ribbon, each corresponding to a pad. At least one soldering position on the solder ribbon remains soldered to a pad. The protective adhesive layer covers the surface of the battery cell body, specifically covering the positions where the solder ribbon and pads are soldered together. The protective adhesive layer should cover a portion of the battery cell body, with particular emphasis on the positions where the solder ribbon and pads are soldered. Covering the soldering positions and part of the battery cell body with the protective adhesive layer enhances structural stability, reduces cell breakage and power decay during load testing, resists thermal stress to prevent solder joint detachment, fills microcracks, and improves module reliability.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a battery module and a back contact battery. Background Technology

[0002] Back-contact solar cells, as a high-efficiency photovoltaic technology, significantly improve photoelectric conversion efficiency because both positive and negative electrodes (including fine grid lines and pads) are located on the back of the cell, with no grid lines obstructing the front, making them a research hotspot in recent years. In the structure of a back-contact solar cell module, the pads, as key nodes for current collection, connect to the fine metal grid lines on the back of the cell. Solder ribbons are welded to the pads to interconnect multiple cells and transmit current. However, existing back-contact solar cell modules still have reliability defects in practical applications: because the solder ribbons and grid lines are located on the back of the cell, the residual thermal stress after welding is relatively large. During reliability tests such as static load and dynamic load tests, the cell is prone to breakage at the edges due to excessive deformation, leading to excessive power decay. On the other hand, residual thermal stress can also cause cell warping. During thermal cycling tests, the solder joints at the head and tail of the cell are prone to detachment, further increasing the risk of module failure. In addition, the cut edges of the solar cells may have defects such as microcracks due to process errors, which can easily become the initiation point of cell breakage under load. However, there is a lack of effective solutions to the above problems in the existing technology, which seriously restricts the reliability of back contact solar cell modules. Utility Model Content

[0003] Therefore, it is necessary to provide a battery assembly and a back-contact battery to address the reliability risks of back-contact battery assemblies.

[0004] A battery assembly includes:

[0005] The battery cell itself;

[0006] Several solder pads are located on one side surface of the solar cell body;

[0007] The solder strip has several soldering positions, each soldering position is used to solder a corresponding pad, and at least one soldering position of the solder strip is soldered to the pad;

[0008] A protective adhesive layer is applied to the surface of the cell body, and the protective adhesive layer covers at least one welding position of the solder ribbon that is soldered to the solder pad.

[0009] In one embodiment, the cell body includes a cut edge and a non-cut edge disposed along the length direction of the cell body; a protective adhesive layer covers at least the cut edge.

[0010] In one embodiment, the surface of the battery cell body is provided with several fine metal grid lines, and the pads are disposed on the fine metal grid lines;

[0011] Several fine metal grid lines are arranged perpendicular to the length direction of the solar cell body;

[0012] Among them, a row of solder pads set along the cutting edge is designated as edge solder pads;

[0013] The welding position of the welding strip is welded to at least one edge welding pad;

[0014] The protective adhesive layer covers at least the welding points where the edge welding pads are welded together.

[0015] In one embodiment, the metal fine gate line includes a positive fine gate line and a negative fine gate line;

[0016] The fine grid lines of the positive electrode and the fine grid lines of the negative electrode are distributed in an interdigitated pattern along the length of the cell body.

[0017] In one embodiment, the protective adhesive layer also covers the non-cut edge, and the protective adhesive layer on the non-cut edge is spaced apart from the protective adhesive layer on the cut edge.

[0018] In one embodiment, the welding position is welded to the solder joint of the pad, and a preset height difference is provided between the surface of the protective adhesive layer facing away from the pad and the solder joint.

[0019] In one embodiment, the protective adhesive layer has a preset width along the length direction perpendicular to the cell body, with one end of the preset width located on the cutting edge and the other end of the preset width located at the boundary of the protective adhesive layer away from the cutting edge.

[0020] In one embodiment, several solder strips are provided, and the same solder strip is soldered to a pad of the same polarity.

[0021] In one embodiment, the cell body includes a front side and a back side, with solder pads, solder ribbons, and a protective adhesive layer all disposed on the back side of the cell body.

[0022] A back-contact battery, comprising any of the battery components described above.

[0023] The aforementioned battery module includes: a battery cell body, several solder pads, solder ribbons, and a protective adhesive layer. Several solder pads are located on one side surface of the battery cell body. Several soldering positions are provided on the solder ribbons, each corresponding to a solder pad. At least one soldering position on the solder ribbon remains soldered to a solder pad. The protective adhesive layer covers the surface of the battery cell body, specifically covering the locations where the solder ribbons and solder pads are soldered together. The protective adhesive layer should cover a portion of the battery cell body, with particular emphasis on the locations where the solder ribbons and solder pads are soldered. Covering the locations where the solder ribbons and solder pads are soldered together and a portion of the battery cell body, the protective adhesive layer provides physical support, enhancing the structural stability of the battery cell body. Especially during reliability tests such as static and dynamic load tests, it effectively mitigates the risk of edge breakage due to excessive deformation of the battery cell, reducing power degradation caused by breakage. Meanwhile, the protective adhesive layer reinforces the welding position between the solder ribbon and the solder pad. Utilizing its own flexibility and adhesion, it resists thermal expansion and contraction caused by thermal stress, reducing the impact of residual thermal stress on the solar cells after welding, minimizing cell warping, and thus preventing solder joint detachment during thermal cycling tests, reducing the risk of module failure. Furthermore, the protective adhesive layer covering certain areas of the solar cell body fills and protects against potential microcracks and other process defects along the cutting edges, preventing these defects from becoming the initiation points for cell breakage under load, comprehensively improving the reliability and lifespan of the back-contact solar module.

[0024] A back-contact battery has the aforementioned beneficial effects. Attached Figure Description

[0025] Figure 1 This is a top view of the battery assembly provided in an embodiment of this application.

[0026] Figure 2 for Figure 1 A top view after the protective adhesive layer is hidden.

[0027] Figure 3 for Figure 1 Side view.

[0028] Icon labels:

[0029] 1000, Cell body; 1001, Cut edge; 1002, Uncut edge; 2000, Pad; 2001, Edge welding pad; 2002, Solder joint; 3000, Welding strip; 4000, Protective adhesive layer; A, Preset height difference; B, Preset width. Detailed Implementation

[0030] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0031] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and 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, and therefore should not be construed as a limitation of this application.

[0032] Furthermore, where the terms "first" and "second" appear, these terms are 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 with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via 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. Similarly, "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.

[0035] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0036] See Figure 1 and Figure 2 As shown, Figure 1 This is a top view of the battery assembly provided in an embodiment of this application. Figure 2 for Figure 1A top view showing the battery assembly with the protective adhesive layer concealed. The battery assembly includes: a battery cell body 1000, several solder pads 2000, solder ribbons 3000, and a protective adhesive layer 4000. The solder pads 2000 are all disposed on one side surface of the battery cell body 1000. The solder ribbons 3000 have several soldering positions, each corresponding to a solder pad 2000. At least one soldering position on the solder ribbon 3000 remains soldered to a solder pad 2000. The protective adhesive layer 4000 covers the surface of the battery cell body 1000, specifically covering the positions where the solder ribbons 3000 and solder pads 2000 are soldered together. The welding position refers to a specific area on the solder ribbon 3000 used for docking and welding with the solder pad 2000. Its distribution, size, and shape can be determined based on the arrangement of the solder pads 2000 on the cell body 1000 and actual connection requirements. Its main function is to achieve mechanical fixation and current transmission between the solder ribbon 3000 and the solder pad 2000 through corresponding welding. At least one welding position of the solder ribbon 3000 must remain welded to the solder pad 2000 to achieve basic interconnection and current transmission between the cell bodies 1000. Since the core function of the protective adhesive layer 4000 is to protect the welding stability of the solder ribbon 3000 and the solder pad 2000, it can cover multiple welding positions. By simultaneously wrapping multiple welding positions and the surrounding cell body 1000 and solder ribbon 3000, it enhances the physical support for multiple welding positions, resists thermal expansion and contraction caused by thermal stress, further reduces the risk of multiple welding positions detaching due to stress, and improves the reliability of the overall welding structure.

[0037] The protective adhesive layer 4000 should cover a portion of the cell body 1000, with a focus on covering the areas where the solder ribbon 3000 and the solder pad 2000 are welded. Depending on the shape and size of the cell and the distribution of the solder ribbon 3000 and the solder pad 2000, the protective adhesive layer 4000 can be configured to cover the vulnerable edges of the cell and the areas where all solder joints are located, ensuring effective protection for critical components.

[0038] The protective adhesive layer 4000 provides physical support to the edges of the cell body 1000, especially the cut edges 1001 of the cell body 1000, enhancing the strength of the cell edges. During reliability tests such as static and dynamic load tests on the module, it effectively mitigates edge breakage caused by excessive deformation of the cells, thereby reducing excessive power attenuation.

[0039] The protective adhesive layer 4000 can resist the thermal expansion and contraction stresses caused by heat, reducing the impact of residual thermal stress after welding on the solar cells and minimizing cell warping. During thermal cycling tests, it effectively prevents the weld joints at the head and tail of the solar cells from detaching due to warping, reducing the risk of module failure. For defects such as microcracks at the cut edge 1001 of the solar cells caused by process errors, the protective adhesive layer 4000 can fill and reinforce these defects, making it less likely for these microcracks to become the initiation point of cell breakage under load, thus improving the overall reliability of the solar cells.

[0040] The protective adhesive layer 4000 can be coated using inkjet printing, which allows for precise control of the adhesive amount and flexible spraying along specific areas such as the cutting edge 1001 and welding positions to form a uniform thin layer, adapting to complex shape coverage requirements. Alternatively, screen printing can be used, where the protective adhesive layer 4000 is mass-printed onto the target area using a pre-set screen, offering high efficiency and stable coating thickness, suitable for large-area continuous coating. Furthermore, other compatible processes can be employed, as long as they achieve tight adhesion between the protective adhesive layer 4000 and the battery cell body 1000, solder ribbon 3000, and solder pad 2000.

[0041] The protective layer 4000 is supported by a protective adhesive, which can be made of conventional protective adhesive materials, such as 70-80% methyl silicone oil, 10-15% silica, 2-4% crosslinking agent and a small amount of catalyst and coupling agent. It has the characteristics of room temperature curing, good flexibility and good adhesion.

[0042] In some embodiments of this application, the battery cell body 1000 has cut edges 1001 and non-cut edges 1002 distributed along its length direction, and the protective adhesive layer 4000 must at least cover the cut edges 1001. Referring to the prior art, during the processing of the battery cell body 1000, in order to meet specific size or assembly requirements, the original battery cell needs to be cut using a cutting process. The edge formed by the cutting process is the cut edge 1001; the original edge that has not undergone the cutting process is the non-cut edge 1002. The cut edge 1001 refers to the edge formed after the battery cell body 1000 has undergone the cutting process, which is prone to defects such as micro-cracks due to cutting process errors; the non-cut edge 1002 refers to the original edge of the battery cell body 1000 that has not undergone the cutting process, and is less prone to process defects than the cut edge 1001. In actual setup, the protective adhesive layer 4000 can extend a certain range from the cut edge 1001 into the interior of the cell body 1000, simultaneously covering the welding position between the solder ribbon 3000 and the solder pad 2000. When covering the cut edge 1001, it is necessary to ensure that the protective adhesive layer 4000 is in close contact with the surface of the cut edge 1001, without any air bubbles or gaps, and the width of the coverage should ideally completely enclose the entire length of the cut edge 1001. For the non-cut edge 1002, whether to cover it can be selected according to actual needs; if covered, the same adhesion and thickness requirements as for the cut edge 1001 must be followed.

[0043] The protective adhesive layer 4000 covers at least the cut edge 1001, directly providing physical support and reinforcement to the cut edge 1001. Since the cut edge 1001 is formed during the cutting process, it is prone to micro-cracks and other process defects. The protective adhesive layer 4000 fills these micro-cracks, preventing them from expanding into fracture initiation points under static and dynamic loads, significantly reducing the risk of cell edge breakage. Simultaneously, the protective adhesive layer 4000 tightly bonds with the cut edge 1001, enhancing its structural strength. When the module is under load, it reduces edge damage caused by excessive deformation of the cell, thereby preventing excessive power degradation. In addition, the protective adhesive layer 4000 covers the cutting edge 1001 and the welding position of the solder strip 3000 and the solder pad 2000. With its own flexibility and adhesion, it can resist the thermal expansion and contraction caused by thermal stress, further alleviate the impact of residual thermal stress after welding on the cell, reduce cell warping, and thus reduce the possibility of solder joint detachment during thermal cycling test, thereby improving the overall reliability of the back contact cell module.

[0044] In some embodiments of this application, the surface of the battery cell body 1000 is provided with several fine metal grid lines. These fine metal grid lines are arranged perpendicular to the length direction of the battery cell body 1000, and the pads 2000 are disposed on the fine metal grid lines. The fine metal grid lines are thin strip-shaped metal structures disposed on the surface of the battery cell body 1000, and their main function is to collect the current generated by the battery cell. They include positive and negative fine grid lines. They are arranged perpendicular to the length direction of the battery cell body 1000, and the positive and negative fine grid lines are distributed in an interlacing pattern along the length direction of the battery cell body 1000, connecting to the corresponding positive and negative pads 2000 respectively, thereby achieving current collection to the pads 2000.

[0045] Among them, a row of solder pads 2000 arranged along the cutting edge 1001 are called edge solder pads 2001. The soldering position of the solder ribbon 3000 is soldered to at least one edge solder pad 2001, and the protective adhesive layer 4000 covers at least the soldering position where it is soldered to the edge solder pad 2001. The edge solder pad 2001 is part of the solder pads 2000, and its essence is the same as other solder pads 2000. They are all structures arranged on the surface of the cell body 1000 for soldering to the solder ribbon 3000 to achieve current transmission and cell interconnection. The row of pads 2000 positioned along the cutting edge 1001 is defined separately as edge pads 2001. This is solely for the purpose of more clearly identifying the pads 2000 at this specific location—the group of pads near the cutting edge 1001—in description and research. This clarifies their positional relationship with the cutting edge 1001 and highlights their role as a key protected element in technical solutions such as protective adhesive layer 4000 coverage and stress protection. They are not fundamentally different from other pads 2000 in structure or function. This definition method aims to make the technical description more precise and the logic clearer, facilitating targeted explanations of the design and function of the pads in this area.

[0046] Specifically, the fine metal grid lines need to be evenly distributed on the surface of the cell body 1000 to ensure that the current can be efficiently collected to the solder pads 2000. The edge solder pads 2001 need to be closely arranged on the fine metal grid lines near the cut edge 1001, and their positions should be precisely aligned with the corresponding welding positions on the solder ribbon 3000 to ensure the stability of the welding. When the solder ribbon 3000 is welded to the edge solder pad 2001, it is necessary to ensure that the welding position completely covers the surface of the edge solder pad 2001 to form a good electrical connection. When the protective adhesive layer 4000 covers the welding position where it is welded to the edge solder pad 2001, it should simultaneously cover the corresponding portion of the solder ribbon 3000, the edge solder pad 2001, and the surrounding portion of the cell body 1000. The protective adhesive layer 4000 needs to be tightly adhered to the surfaces of these structures, with uniform thickness and no air bubbles or gaps, to achieve comprehensive and effective protection.

[0047] The fine metal grid lines are arranged perpendicular to the length of the cell body 1000. Together with the solder pads 2000, especially the edge solder pads 2001, they can more efficiently collect current and ensure smooth current transmission. Secondly, the solder ribbon 3000 is welded to the edge solder pads 2001. Combined with the protective adhesive layer 4000 covering the weld area, the protective adhesive layer 4000 provides physical support to the weld, enhancing its strength. Since the edge solder pads 2001 are close to the cut edge 1001, which is prone to microcracks, the protective adhesive layer 4000, while covering the weld area, also protects the cell body 1000 near the cut edge 1001, reducing the risk of microcracks propagating under load and lowering the possibility of cell breakage.

[0048] In addition, the protective adhesive layer 4000 can resist thermal expansion and contraction caused by thermal stress, alleviate the impact of residual thermal stress after welding on the weld joint between the edge welding pad 2001 and the welding strip 3000, reduce the warping of the cell caused by thermal stress, and thus reduce the probability of solder joint detachment during thermal cycling tests. At the same time, the protective adhesive layer 4000 covers the cell body 1000, the edge welding pad 2001, and the welding position of the welding strip 3000, which can improve the overall structural strength of the cell edge. In reliability tests such as static load and dynamic load, it reduces edge damage caused by excessive deformation of the cell, avoids excessive power attenuation, and significantly improves the reliability of the back contact cell module.

[0049] In some embodiments of this application, the metal fine grid lines are divided into positive electrode fine grid lines and negative electrode fine grid lines, which are arranged alternately along the length direction of the battery cell body 1000 to form a distribution pattern similar to interlocking fingers, and are arranged perpendicular to the length direction of the battery cell body 1000. The pads 2000 are respectively disposed on the corresponding positive electrode fine grid lines and negative electrode fine grid lines.

[0050] The finger-like distribution makes the fine grid lines of the positive and negative electrodes more uniformly distributed on the surface of the cell body 1000, maximizing the utilization of the light-receiving area of ​​the cell body 1000, reducing the current transmission path length, lowering resistance loss, and improving current collection efficiency. At the same time, this distribution method can make the current distribution more even, avoiding the hot spot effect caused by excessive local current concentration, and enhancing the power generation performance of the cell.

[0051] The metal grid lines include positive and negative grid lines, and the corresponding pads 2000 are also divided into positive and negative pads 2000. For example, the positive and negative grid lines are alternately distributed in a finger-like pattern along the length of the cell body 1000. The positive pads 2000 are spaced apart on the positive grid lines, and each positive pad 2000 is electrically connected to the corresponding positive grid line. The negative pads 2000 are correspondingly spaced on the negative grid lines, and each negative pad 2000 is electrically connected to the corresponding negative grid line. The positions of the positive and negative pads 2000 are staggered to avoid direct contact between the positive and negative electrodes.

[0052] In some embodiments of this application, the protective adhesive layer 4000 not only covers the cut edge 1001, but also extends to and covers the non-cut edge 1002. The two protective adhesive layers 4000 maintain a certain distance from each other and are not connected to each other. Each layer independently covers the corresponding edge area and simultaneously covers the welding positions of the solder strip 3000 and the solder pad 2000 near the edge. The thickness is uniform and the fit is tight.

[0053] Covering the non-cut edge 1002 provides protection for the non-cut edge 1002 of the cell body 1000, further enhancing the overall structural strength of the cell edge. The spaced arrangement prevents the protective adhesive layer 4000 from forming a continuous large-area coverage on the surface of the cell body 1000, reducing additional stress on the cell body 1000 caused by the shrinkage or expansion of the protective adhesive layer 4000 material. Simultaneously, it protects both the cut edge 1001 and the non-cut edge 1002, reducing the risk of cell breakage in different edge areas and improving module reliability.

[0054] In some embodiments of this application, reference is made to the appended specification. Figure 3 , Figure 3 for Figure 1 The side view shows the solder joint 2002 formed by soldering the solder ribbon 3000 to the solder pad 2000. A protective adhesive layer 4000 covers the solder joint 2002 and its surrounding area. A preset height difference A exists between the surface of the protective adhesive layer 4000 facing away from the solder pad 2000 and the highest point of the solder joint 2002. This means the protective adhesive layer 4000 completely encloses the solder joint 2002, and its surface is higher than the solder joint 2002. This height difference can be set according to the size of the solder joint 2002 and the protection requirements, ensuring that the solder joint 2002 is completely inside the protective adhesive layer 4000. As mentioned above, the soldering position corresponds to the solder joint 2002, and the protective adhesive layer 4000 should cover both the soldering position and the area above the solder joint 2002 to ensure effective protection.

[0055] The preset height difference A refers to the height difference between the surface of the protective adhesive layer 4000 facing away from the pad 2000 and the solder joint 2002. Its value is limited to 260μm-400μm (micrometers). That is, the surface of the protective adhesive layer 4000 facing away from the pad 2000 needs to be 260μm-400μm higher than the solder joint 2002 to ensure that the protective adhesive layer 4000 completely covers the solder joint 2002 and enhances the protection effect of the solder joint 2002.

[0056] The preset height difference A ensures that the protective adhesive layer 4000 completely covers the solder joint 2002, preventing the solder joint 2002 from being directly exposed to the external environment and protecting it from external mechanical damage or corrosion. Simultaneously, the protective adhesive layer 4000, through its own thickness, buffers the impact of external loads on the solder joint 2002, reducing the stress on it and lowering the possibility of solder joint 2002 detachment. Especially during thermal cycling tests, it better resists the effects of thermal stress on the solder joint 2002, maintaining its stability.

[0057] In some embodiments of this application, reference is made to the appended specification. Figure 1 The protective adhesive layer 4000 has a preset width B in the direction perpendicular to the length of the cell body 1000. One end of this width starts at and covers the cut edge 1001, and the other end extends to a certain position inside the cell body 1000, forming the boundary of the protective adhesive layer 4000 away from the cut edge 1001. The width must cover the welding position of the solder strip 3000 and the edge welding pad 2001 near the cut edge 1001 and the surrounding part of the cell body 1000, ensuring that critical areas are within the protection range. The preset width B refers to the width of the protective adhesive layer 4000 in the direction perpendicular to the length of the cell body 1000, and its value is limited to 0.8cm-1.2cm. The boundary of the preset width B is: one end is located on the cutting edge 1001, and the other end is located at the first solder joint 2002 closest to the cutting edge 1001 (that is, the position of the edge welding pad 2001). That is, the protective adhesive layer 4000 extends from the cutting edge 1001 to the first solder joint 2002, covering the area between the cutting edge 1001 and the first solder joint 2002.

[0058] The preset width B allows the protective adhesive layer 4000 to extend sufficiently from the cut edge 1001 into the interior of the cell body 1000. This not only protects the cut edge 1001 but also covers the nearby welding positions and part of the cell body 1000, enhancing the structural strength of the area surrounding the cut edge 1001. When the cell is under load, it can distribute stress over a wider area, reducing breakage of the cut edge 1001 caused by localized stress concentration. Simultaneously, it provides more stable protection for the welding positions, improving the overall comprehensiveness of the protection effect.

[0059] In some embodiments of this application, there are multiple solder ribbons 3000, and multiple welding positions of each solder ribbon 3000 are welded one-to-one with the same polarity solder pads 2000 on the battery cell body 1000. That is, one solder ribbon 3000 is only connected to the positive electrode solder pad 2000 or only connected to the negative electrode solder pad 2000. Solder pads 2000 of different polarities are connected by different solder ribbons 3000. The welding positions of the solder ribbons 3000 and the corresponding polarity solder pads 2000 are precisely aligned to ensure that the welding is firm and the electrical connection is good.

[0060] Assume four solder strips 3000, two of which are positive electrode solder strips 3000 and two are negative electrode solder strips 3000. The first positive electrode solder strip 3000 is soldered one-to-one with the front half of the positive electrode pads 2000 distributed along the length of the cell body 1000; the second positive electrode solder strip 3000 is soldered one-to-one with the rear half of the positive electrode pads 2000; similarly, the first negative electrode solder strip 3000 is soldered one-to-one with the front half of the negative electrode pads 2000, and the second negative electrode solder strip 3000 is soldered one-to-one with the rear half of the negative electrode pads 2000. In this way, each solder strip 3000 is connected only to pads 2000 of the same polarity, achieving distributed current transmission, reducing the load pressure on a single solder strip 3000, and avoiding short circuits between the positive and negative electrodes.

[0061] Connecting the same solder ribbon 3000 to the same polarity pad 2000 avoids short circuits between pads 2000 of different polarities via the solder ribbon 3000, ensuring the safety and accuracy of current transmission. Connecting multiple solder ribbons 3000 to pads 2000 of different polarities distributes the current transmission load, improves current transmission efficiency, and facilitates independent management and maintenance of circuits of different polarities. This reduces the risk of the entire component failing due to a single solder ribbon 3000 failure, enhancing component stability.

[0062] In some embodiments of this application, the front side of the cell body 1000 is a light-receiving surface, and the back side is a non-light-receiving surface. All solder pads 2000 are disposed on the back side of the cell body 1000. The fine metal grid lines are also distributed on the back side and connected to the solder pads 2000. The solder ribbon 3000 is connected to the solder pads 2000 on the back side through the welding position. The protective adhesive layer 4000 covers the back side of the cell body 1000, wrapping the cut edge 1001 on the back side, the welding position of the solder ribbon 3000 and the solder pad 2000, and part of the back side area.

[0063] By placing the solder pads 2000, solder ribbons 3000, and protective adhesive layer 4000 on the back side, sunlight is prevented from being blocked by grid lines or solder ribbons 3000 on the front side, maximizing the utilization of the front light-receiving area and improving photoelectric conversion efficiency. Simultaneously, the protective adhesive layer 4000 on the back side provides more direct protection for the solder structure and cut edges 1001, reducing the impact of the external environment on critical back-side structures and further enhancing the reliability and lifespan of the module.

[0064] Specifically, to verify the beneficial effects of the above scheme, a protective adhesive group and a conventional group were set up for comparative testing. The modules were tested under different processes, including static load (SML), dynamic load (DML), and thermal cycling (TC200). The battery modules of the protective adhesive group were configured according to the aforementioned technical scheme, while the conventional group was configured according to the battery modules in the existing technology. The specific process testing methods can be found in the existing technology.

[0065] The results are as follows: In the three-point bend strength test, the standard group achieved 180 MPa (megapascals), which is lower than the 190 MPa of the IEC 61215 standard, while the battery pack using protective adhesive reached 270 MPa, which is not only greater than the standard group, but also meets the industry standard.

[0066] In the UV60 ultraviolet aging test, the protective colloid group data was △E=2, which meets the IEC 61215 standard △E<3; it meets the weather resistance requirements, indicating that it has little discoloration under long-term ultraviolet irradiation, good material stability, and is not prone to performance degradation due to ultraviolet aging.

[0067] In the PCT24 high-pressure boiling test, the protective adhesive layer did not delaminate from the battery cell, indicating that the protective adhesive layer is firmly bonded to the battery cell body, solder ribbons and other structures, and will not delaminate under harsh environments, thus ensuring the continuity of protection and structural stability.

[0068] In addition, in the SML power attenuation test, the standard group had an attenuation of 4.96%, while the protective adhesive group had an attenuation of 1.28%, which is lower than the IEC standard of 3%.

[0069] In the DML power attenuation test, the conventional group reached 3.09%, exceeding the IEC standard of 3% and thus failing, while the protective adhesive group only reached 0.75%, which met the standard.

[0070] In the TC200 thermal cycling test, the power attenuation of the conventional group reached 2.39%, and the desoldering rate was 10.97%; the power attenuation of the protective adhesive group was only 0.04%, far lower than the 4% of the IEC standard, and the desoldering rate was 3.2%, which is significantly lower than that of the conventional group.

[0071] Based on the above experimental results, the protective adhesive group passed all tests and outperformed the conventional group. The power decay and desoldering rate of TC200 were also significantly improved, effectively reducing the load risk caused by cell defects and the desoldering risk caused by thermal stress.

[0072] Among them, UV60 refers to the ultraviolet aging test (usually 60 hours of ultraviolet light irradiation), and ΔE is an indicator that measures the color change of the material after ultraviolet irradiation. A qualified UV60 ΔE value for the protective adhesive indicates that it shows minimal discoloration under long-term ultraviolet irradiation, meets weather resistance requirements, has good material stability, and is not prone to performance degradation due to ultraviolet aging. PCT24 refers to the 24-hour high-pressure boiling test (tested in a high-temperature and high-humidity environment), used to evaluate the bonding reliability between materials. IEC 61215 is a photovoltaic module performance and reliability standard used to regulate various test indicators for photovoltaic modules.

[0073] See the table below for details:

[0074]

[0075] A back contact battery includes the aforementioned battery assembly, which consists of a battery cell body 1000, a solder pad 2000 disposed on its surface, a solder ribbon 3000 soldered to the solder pad 2000, and a protective adhesive layer 4000 covering key areas. The various parts are assembled according to their respective arrangements to form a complete back contact battery structure.

[0076] This back-contact battery possesses all the beneficial effects of the aforementioned battery modules. It can improve photoelectric conversion efficiency due to the unobstructed front side, and reduce problems such as edge breakage and solder joint detachment through the setting of protective adhesive layer 4000 and other structures, thereby reducing power attenuation and module failure risk. At the same time, it optimizes the current transmission path and distribution, thus improving the overall reliability, stability and power generation performance of the back-contact battery.

[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A battery assembly, characterized in that, The battery assembly includes: Battery cell body (1000); Several pads (2000) are disposed on one side surface of the battery cell body (1000); The solder strip (3000) has several welding positions, each welding position is used to weld a corresponding pad (2000), and at least one welding position of the solder strip (3000) is welded to the pad (2000); A protective adhesive layer (4000) covers the surface of the cell body (1000), and the protective adhesive layer (4000) covers at least one of the solder ribbons (3000) at the solder pads (2000) where they are soldered.

2. The battery assembly according to claim 1, characterized in that, The battery cell body (1000) includes a cut edge (1001) and a non-cut edge (1002) disposed along the length direction of the battery cell body (1000); the protective adhesive layer (4000) covers at least the cut edge (1001).

3. The battery assembly according to claim 2, characterized in that, The surface of the battery cell body (1000) is provided with several fine metal grid lines, and the pads (2000) are provided on the fine metal grid lines; Several of the aforementioned fine metal grid lines are arranged perpendicular to the length direction of the battery cell body (1000); Among them, a row of pads (2000) arranged along the cutting edge (1001) is designated as edge solder pads (2001). The welding position of the welding strip (3000) is welded to at least one of the edge welding discs (2001); The protective adhesive layer (4000) covers at least the welding position where it is welded to the edge welding pad (2001).

4. The battery assembly of claim 3, wherein, The metal fine grid lines include positive electrode fine grid lines and negative electrode fine grid lines; The positive and negative fine grid lines are distributed in an interdigitated pattern along the length of the battery cell body (1000).

5. The battery assembly of claim 2, wherein, The protective adhesive layer (4000) also covers the non-cut edge (1002), and the protective adhesive layer (4000) on the non-cut edge (1002) is spaced apart from the protective adhesive layer (4000) on the cut edge (1001).

6. The battery assembly of claim 1, wherein, The welding position is welded to the solder joint (2002) of the solder pad (2000), and a preset height difference is provided between the surface of the protective adhesive layer (4000) facing away from the solder pad (2000) and the solder joint (2002).

7. The battery assembly of claim 2, wherein, The protective adhesive layer (4000) has a preset width along the length direction perpendicular to the battery cell body (1000). One end of the preset width is located on the cutting edge (1001), and the other end of the preset width is located at the boundary of the protective adhesive layer (4000) away from the cutting edge (1001).

8. The battery assembly of claim 1, wherein, The solder strip (3000) is provided in several strips, and the same solder strip (3000) is soldered to the solder pad (2000) of the same polarity.

9. The battery assembly according to claim 1, characterized in that, The battery piece body (1000) comprises a front surface and a back surface, and the solder pad (2000), the solder strip (3000) and the protective adhesive layer (4000) are arranged on the back surface of the battery piece body (1000).

10. A back contact cell characterized by, The battery assembly comprises the battery piece according to any one of claims 1-9.

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