Photovoltaic module and photovoltaic system

Abstract

The invention discloses a photovoltaic module and a photovoltaic system. The photovoltaic module comprises a battery piece, a bonding layer and an electric connecting piece, an electrode is arranged on the surface of the battery piece, and the electric connecting piece is fixed and conductively connected with the electrode through a bonding layer; wherein the electrode at least comprises X, the bonding layer at least comprises Y, X is a metal element in the bonding layer, and Y is a metal element in the electrode. The element X in the bonding layer is at least partially diffused into the electrode, and the element Y in the electrode is at least partially diffused into the bonding layer, so that the electrical connector and the electrode can form an intermetallic compound at a bonding interface, and a certain bonding force between the bonding layer and the electrode is ensured. The connection performance and the conductive performance between the electric connector and the electrode are improved, so that the use performance of the photovoltaic module is improved.

Description

Technical Field

[0001] The present application belongs to the field of photovoltaic technology, and specifically relates to a photovoltaic module and a photovoltaic system. Background Art

[0002] Photovoltaic cells are semiconductor devices that can convert solar energy into electrical energy. Under lighting conditions, a photocurrent effect will be generated inside the photovoltaic cell, and the electrical energy will be output through the electrodes on the cell. In the photovoltaic module manufacturing process, a plurality of cells are usually connected in series using a welding ribbon to form a cell string, and then the cell string is packaged to obtain a photovoltaic module. Among them, when a plurality of cells are connected in series using a welding ribbon, the welding ribbon is welded and fixed to the electrode on the cell. If the welding between the welding ribbon and the electrode is poor, it will affect the connection strength and conductivity of the welding ribbon and the electrode. Summary of the invention

[0003] The present application aims to provide a photovoltaic module and a photovoltaic system, which can solve the problem that when a plurality of solar cells are connected in series using a welding ribbon, if the welding between the welding ribbon and the electrode is poor, the connection strength and conductivity of the welding ribbon and the electrode will be affected.

[0004] In order to solve the above technical problems, this application is implemented as follows:

[0005] In a first aspect, an embodiment of the present application proposes a photovoltaic module, comprising: a cell, a bonding layer and an electrical connector; an electrode is provided on the surface of the cell, and the electrical connector is fixed and conductively connected to the electrode through the bonding layer; wherein the electrode includes at least X, and the bonding layer includes at least Y, X is a metal element in the bonding layer, and Y is a metal element in the electrode.

[0006] In a second aspect, an embodiment of the present application provides a photovoltaic system, comprising the photovoltaic component described in the first aspect.

[0007] In the embodiment of the present application, an electrode is provided on the surface of the cell, and the electrical connector is connected to the electrode, and the electrode collects the carriers generated by the cell, and the electrical connector collects and conducts the cell. Furthermore, by at least partially diffusing the X element in the bonding layer into the electrode, and at least partially diffusing the Y element in the electrode into the bonding layer, the electrical connector and the electrode are prompted to form an intermetallic compound at the bonding interface, so as to ensure the structural strength of the connection interface between the electrical connector and the electrode, and further ensure that there is a certain bonding force between the bonding layer and the electrode, which is conducive to improving the connection performance and conductivity between the electrical connector and the electrode, thereby improving the performance of the photovoltaic module.

[0008] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0010] Figure 1 is a schematic structural diagram of the photovoltaic assembly at the connection between the electrical connector and the electrode according to an embodiment of the present application;

[0011] Figure 2 is one of the SEM images of the connection structure between the bonding layer and the electrode according to an embodiment of the present application;

[0012] Figure 3 This is a second SEM image of the connection structure between the bonding layer and the electrode according to an embodiment of the present application;

[0013] Figure 4 is a schematic diagram of element distribution of an electrode portion of a photovoltaic module according to an embodiment of the present application;

[0014] Figure 5 is a schematic diagram of element distribution of a bonding layer portion of a photovoltaic module according to an embodiment of the present application;

[0015] Figure 6 is a schematic diagram of the diffusion depth of each element in the electrode according to an embodiment of the present application;

[0016] Figure 7 is a schematic diagram of the diffusion depth of the silver element in the bonding layer according to an embodiment of the present application;

[0017] Figure 8 is a distribution diagram of various elements in the bonding layer and electrode connection structure according to an embodiment of the present application;

[0018] Fig. 9 This is another distribution diagram of each element in the bonding layer and electrode connection structure according to an embodiment of the present application.

[0019] Reference numerals:

[0020] 10: battery cell; 11: electrode; 111: first electrode portion; 112: second electrode portion; 20: electrical connector; 21: conductive body; 30: bonding layer; 31: first bonding portion; 32: second bonding portion; 101: intermetallic compound layer; S1: first region; S2: second region. DETAILED DESCRIPTION

[0021] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0022] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0023] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0024] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] The photovoltaic assembly and photovoltaic system provided in the embodiments of the present application are described in detail below through specific embodiments and their application scenarios in conjunction with the accompanying drawings.

[0026] like Figures 1 to 3As shown, according to some embodiments of the present application, the photovoltaic module includes: a battery cell 10, a bonding layer 30 and an electrical connector 20; the surface of the battery cell 10 is provided with an electrode 11, and the electrical connector 20 is connected to the electrode 11 through the bonding layer 30; wherein the electrode 11 includes at least X, and the bonding layer 30 includes at least Y, X is a metal element in the bonding layer 30, and Y is a metal element in the electrode 11.

[0027] It should be understood that the electrical connector 20 may include a conductive body 21. The above-mentioned bonding layer 30 may be a solder paste or the like independently provided from the electrical connector 20, or may be a tin alloy layer on the periphery of the conductive body 21 of the electrical connector 20. That is, between the conductive body 21 and the electrode 11, there may be one bonding layer 30 such as a tin alloy layer, or there may be two bonding layers 30 such as independently provided solder paste and tin alloy layers. Generally speaking, the bonding performance between the bonding layer 30 and the conductive body of the electrical connector 20 is easy to meet the product reliability requirements, while the bonding performance between the bonding layer 30 and the electrode 11 is more difficult to meet the reliability requirements.

[0028] In the embodiment of the present application, the surface of the cell 10 is provided with an electrode 11, so that the electrical connector 20 is connected to the electrode 11, and the electrode 11 collects the carriers generated by the cell 10, and the electrical connector 20 collects and leads the cell 10. Then, by partially diffusing the X element in the bonding layer 30 into the electrode 11, and partially diffusing the Y element in the electrode 11 into the bonding layer 30, the bonding layer 30 and the electrode 11 are prompted to form an intermetallic compound (IMC) at the bonding interface, so as to ensure the structural strength of the bonding interface between the bonding layer 30 and the electrode 11, and further ensure a certain bonding force between the bonding layer 30 and the electrode 11, so as to improve the connection performance and conductivity between the electrical connector 20 and the electrode 11, thereby improving the performance of the photovoltaic module.

[0029] Specifically, Figure 1 As shown, the electrical connector 20, the bonding layer 30 and the electrode 11 are all arranged on the surface of the battery cell 10, wherein the electrical connector 20 includes a conductive body 21. From top to bottom on the surface of the battery cell 10 are the conductive body 21, the bonding layer 30 and the electrode 11; Figure 8 and Fig. 9 As shown, the intermetallic compound layer 101 is formed between the bonding layer 30 and the electrode 11 .

[0030] It can be understood that in the present application, when the electrical connector 20 and the electrode 11 are connected by an interconnection process such as welding, the X element in the bonding layer 30 will diffuse into the electrode 11, and at the same time, the Y element in the electrode 11 will also diffuse into the bonding layer 30. This is conducive to the formation of an intermetallic compound layer 101 at the junction between the bonding layer 30 and the electrode 11, thereby ensuring that a relatively stable connection structure can be formed at the interface between the bonding layer 30 and the electrode 11; at the same time, the interaction of metal elements between the electrode 11 and the bonding layer 30 is conducive to the close connection between the electrode 11 and the bonding layer 30.

[0031] In specific applications, a low-temperature interconnection process can be used to connect the electrode 11 and the electrical connector 20. For example, a low-temperature infrared welding process, a low-temperature laser welding process, a low-temperature coating process, a glue point interconnection process, etc. can be used to connect the electrode 11 and the electrical connector 20, so that it can be applied to the production process of low-temperature batteries. Of course, the specific connection process between the electrode 11 and the electrical connector 20 can be flexibly set according to actual needs and is not limited here.

[0032] In some embodiments, the conductive body 21 can be made of a conductive material, for example, a conductive metal material such as copper, gold, silver, etc. can be made into a metal wire to ensure that the conductive body 21 has a certain mechanical strength and conductive performance. Furthermore, at least one bonding layer 30 is provided between the conductive body 21 and the electrode 11, and the bonding layer 30 is provided to improve the weldability of the electrical connector 20 and the electrode 11, thereby facilitating the welding connection between the electrical connector 20 and the electrode 11.

[0033] In some embodiments, the bonding force between the bonding layer 30 and the electrode 11 is greater than or equal to 0.5 N / mm 2 In the present application, by allowing the metal elements between the bonding layer 30 and the electrode 11 to diffuse mutually, the bonding force between the bonding layer 30 and the electrode 11 can be improved, and the bonding force can be ensured to be greater than or equal to 0.5 N / mm 2 This can further ensure the connection strength between the bonding layer 30 and the electrode 11, thereby improving the connection performance and conductivity between the electrical connector 20 and the electrode 11.

[0034] Specifically, the bonding force between the bonding layer 30 and the electrode 11 is 0.5 N / mm 2 , 0.7N / mm 2 , 0.8N / mm 2 , 1N / mm 2 , 1.5N / mm 2 , 2N / mm 2 , 5N / mm 2 , 10N / mm 2Etc. Among them, the test method of the bonding force between the bonding layer 30 of the electrical connector 20 and the electrode 11 can be tested with reference to GB / T31985, which will not be described in detail here.

[0035] In other embodiments, X is tin (Sn). It is understood that tin has good electrical conductivity, good fluidity after heating, and good affinity with conductive metals such as gold, silver, and copper. Therefore, by setting the tin element in the bonding layer 30, the solderability of the bonding layer 30 and the electrode 11 is improved, and the welding operation of the electrical connector 20 and the electrode 11 is facilitated. At the same time, during the welding process, the tin element in the bonding layer 30 diffuses into the electrode 11, which helps to improve the material wettability and fluidity of the bonding layer 30 and the electrode 11 at the interface, so that a relatively stable and dense intermetallic compound layer 101 can be quickly formed at the interface, so that the electrical connector 20 can be firmly welded and fixed on the electrode 11, and the electrical connector 20 and the electrode 11 can maintain good conductivity.

[0036] In other embodiments, Y is at least one of silver (Ag), copper (Cu), aluminum (Al), and nickel (Ni). It is understandable that the Y element is one of the components constituting the electrode 11. By setting the Y element to at least one of silver, copper, aluminum, and nickel, the conductive performance requirements of the electrode 11 are met, and it is also convenient for the Y element to diffuse into the bonding layer 30 when the electrode 11 is interconnected with the electrical connector 20, thereby forming a stable intermetallic compound between the electrode 11 and the bonding layer 30.

[0037] Optionally, the electrode 11 may be a metal electrode in the form of a combination of a sheet and a powder, a metal electrode in the form of a sphere and a powder, or a nano-electrode, so as to ensure the connection performance between the electrode 11 and the battery cell 10, facilitate the connection between the electrode 11 and the electrical connector 20, and ensure the collection and transmission capabilities of the electrode 11 for the carriers generated by the battery cell 10.

[0038] Alternatively, if Figure 4 As shown, the electrode 11 includes a first electrode portion 111 and a second electrode portion 112, the first electrode portion 111 is connected to the bonding layer 30, and the second electrode portion 112 is located on the side of the first electrode portion 111 away from the bonding layer 30; wherein the X content in the first electrode portion 111 is greater than the X content in the second electrode portion 112.

[0039] It should be noted that in this application, an energy spectrometer is used in conjunction with a scanning electron microscope to perform element detection and analysis on the cross-section of the connection structure interface between the bonding layer 30 and the electrode 11. The specific experimental method for element analysis using an energy spectrometer and a scanning electron microscope can be performed with reference to related technologies and will not be described in detail here. Figure 4 As shown, Figure 4The left side in the middle is a scanning electron microscope (SEM) image of the electrode 11 , and the right side is a schematic diagram of the distribution of each element in the electrode 11 .

[0040] Furthermore, if Figure 4 As shown in Figure b in the upper right corner, the bright spots in the figure represent the distribution of tin elements in the electrode. It can be seen that there are more bright spots in the upper part of the figure than in the lower part, indicating that the X content in the electrode 11 close to the bonding layer 30 is greater than the X content in the part far from the bonding layer 30, that is, the X content in the first electrode portion 111 is greater than the X content in the second electrode portion 112.

[0041] In the embodiment of the present application, the first electrode portion 111 is closer to the bonding layer 30, and the X content in the first electrode portion 111 is greater than the X content in the second electrode portion 112 by adjusting the process temperature, time, etc., to ensure that the first electrode portion 111 can form a stable intermetallic compound at the junction with the bonding layer 30, thereby ensuring the connection performance between the electrode 11 and the bonding layer 30 while taking into account energy consumption and process efficiency.

[0042] It is understood that the X content may include the mass percentage content or atomic percentage content of the X element in the electrode 11. Further, the X content in this embodiment and the following embodiments refers to the atomic percentage content of the X element.

[0043] Alternatively, if Figure 4 As shown, the thickness of the first electrode portion 111 is greater than or equal to 0.2 μm and less than or equal to 4 μm in a direction perpendicular to the surface of the battery cell 10. Specifically, the thickness of the first electrode portion 111 can be set to any value such as 0.2 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, or a range between any two values.

[0044] In the embodiment of the present application, the thickness of the first electrode portion 111 is set between 0.2 μm and 4 μm to ensure that the X element in the bonding layer 30 is fully diffused into the electrode 11, so that the X element in the first electrode portion 111 can be tightly combined with the metal element in the first electrode portion 111, which is conducive to the formation of a relatively stable and dense intermetallic compound layer 101 between the electrode 11 and the bonding layer 30, providing sufficient metal elements therefor, and the diffusion of the X element with a large content in the first electrode portion 111 is conducive to the reliable connection between the intermetallic compound layer 101 and the electrode 11 and the bonding layer 30 to avoid delamination, thereby realizing the connection function between the electrical connector 20 and the electrode 11.

[0045] Alternatively, if Figure 4 As shown in FIG. 2 b, the X content in the electrode 11 decreases from the first electrode portion 111 to the second electrode portion 112.

[0046] In the embodiment of the present application, by setting from the first electrode portion 111 to the second electrode portion 112, the X content in the electrode 11 shows a decreasing trend, so that the X content of the first electrode portion 111 close to the bonding layer 30 is relatively large, which can meet the reliable connection requirements, and the X content of the second electrode portion 112 away from the bonding layer 30 is relatively small, which can reduce process energy consumption and improve efficiency. Further, it can be a gradually decreasing trend. In this way, it can ensure that the content distribution of the X element in the entire electrode 11 is relatively more uniform, thereby avoiding the problem of local easy fracture of the electrode 11 due to local stress mutation in the electrode 11, and improving the service life of the electrode.

[0047] In some embodiments, along the direction perpendicular to the surface of the cell 10, the diffusion depth of X in the electrode 11 is H1, and the thickness of the electrode 11 is H2, satisfying: H1 / H2≥50%. Specifically, H1 / H2 can be set to: 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc.

[0048] In the embodiment of the present application, by setting the diffusion depth of the X element in the electrode 11 to account for more than 50% of the total thickness of the electrode 11, it is ensured that the X element in the bonding layer 30 is fully diffused into the electrode 11, so that a relatively uniform and dense intermetallic compound layer 101 can be formed in the electrode 11 at the junction with the bonding layer 30, thereby improving the bonding strength and conductive performance between the electrical connector 20 and the electrode 11. In addition, the greater the diffusion depth of the X element, the more favorable it is for the reliable connection between the electrode 11 and the bonding layer 30.

[0049] It is understandable that if the H1 / H2 is less than 50%, the diffusion depth of X in the electrode 11 is shallow, that is, the X element in the bonding layer 30 does not diffuse sufficiently into the electrode 11, which will affect the formation of intermetallic compounds in the electrode 11, and further affect the connection and fixation between the electrode 11 and the electrical connector 20.

[0050] It should be noted that the diffusion depth and thickness in the embodiment of the present application refer to the diffusion depth and thickness corresponding to a certain position in the electrode 11 in the direction perpendicular to the battery surface. For example, the specific measurement method of the above-mentioned diffusion depth H1 is: by detecting the diffusion depth and electrode thickness of the X element at a certain position of the electrode 11, at least three measurement values ​​are detected, and the average of at least three measurement values ​​is the diffusion depth H1 finally detected. The calculation methods of other diffusion depths and thicknesses are executed with reference to the above, and will not be repeated below.

[0051] In some embodiments, the diffusion depth of the X element in the electrode 11 can also be analyzed and detected by using an energy spectrometer. The connection structure between the bonding layer 30 and the electrode 11 is selected as a test sample, and the cross section of the test sample is scanned and analyzed by using an energy spectrometer. When the electrode 11 is tested and analyzed, the interface between the electrode 11 and the bonding layer 30 is used as the starting point, and the scanning analysis is performed from top to bottom along a straight line, so that the following can be obtained: Figure 6 The diffusion depth variation curve of each element in the electrode 11 is shown in FIG. Figure 6 The right side in the middle shows the diffusion depth variation curves of the tin element, the lead element and the bismuth element in the electrode 11 from top to bottom.

[0052] In some embodiments, the diffusion depth of X in the electrode 11 is 2 μm-5 μm. Specifically, the diffusion depth of X in the electrode 11 can be set to 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc.

[0053] In the embodiment of the present application, by setting the diffusion depth of the X element in the electrode 11 to be between 2 μm and 5 μm, it is possible to ensure that a relatively stable intermetallic compound layer 101 of a certain thickness can be formed between the electrode 11 and the bonding layer 30, while preventing excessive diffusion of X to affect the performance of the electrode 11 and the intermetallic compound layer 101.

[0054] It is understandable that if the diffusion depth of X in the electrode 11 is less than 2 μm, the diffusion degree of the X element in the bonding layer 30 into the electrode 11 is insufficient, and the electrode 11 cannot form a relatively stable intermetallic compound layer 101 at the interface with the bonding layer 30, and thus cannot meet the connection strength requirements between the bonding layer 30 and the electrode 11. If the diffusion depth of X in the electrode 11 is greater than 5 μm, that is, the diffusion degree of the X element in the bonding layer 30 into the electrode 11 is high, so that more intermetallic compounds are formed in the electrode 11, due to the greater brittleness of the intermetallic compound layer 101, too thick intermetallic compounds are prone to brittle fracture and other problems during use, which will affect the performance of the electrode 11.

[0055] In some embodiments, within the diffusion depth range of X, the mass percentage of X in the electrode 11 is: 2Wt%-10Wt%. Specifically, the mass percentage of X in the electrode 11 can be set to 2Wt%, 3Wt%, 4Wt%, 5Wt%, 6Wt%, 7Wt%, 8Wt%, 9Wt%, 10Wt%, etc. During specific detection, a section in the thickness direction of the electrode portion can be taken, and then an energy spectrometer or an electron microscope can be used to detect the mass percentage or atomic percentage of X within the diffusion depth range of X. Of course, the detection methods of the mass percentage and atomic percentage of the diffusion of the Y element, lead, and bismuth involved below can also refer to this method.

[0056] It is understandable that, during the welding process of the electrical connector 20 and the electrode 11 through the bonding layer 30, the X element in the bonding layer 30 will diffuse into the electrode 11, and the mass percentage of the X element diffused in the electrode 11 directly affects the structure of the intermetallic compound formed in the electrode 11. If the mass percentage of X in the electrode 11 is too small, a stable intermetallic compound cannot be formed in the portion of the electrode 11 that intersects with the bonding layer 30, and the electrode 11 and the bonding layer 30 cannot form a stable connection structure, and thus the connection requirements of the electrode 11 and the bonding layer 30 cannot be met. If the mass percentage of X in the electrode 11 is too large, too many intermetallic compounds will be formed in the electrode 11, which will easily cause brittle fracture problems in the portion of the electrode 11 that intersects with the bonding layer 30, and will also affect the connection performance of the electrode 11 and the bonding layer 30.

[0057] To this end, in the present application, the mass percentage of X in the electrode 11 is set between 2Wt% and 10Wt%, so that the electrode 11 forms a stable and dense intermetallic compound layer 101 at the junction with the bonding layer 30, while avoiding problems such as brittle fracture of the intermetallic compound formed in the electrode 11, thereby ensuring the connection performance between the electrical connector 20 and the electrode 11.

[0058] In some embodiments, within the diffusion depth range of X, the atomic percentage of X in the electrode 11 is 1At%-9At%. Specifically, the atomic percentage of X in the electrode 11 is 1At%, 2At%, 3At%, 4At%, 5At%, 6At%, 7At%, 8At%, 9At%, etc.

[0059] It is understandable that, during the welding process of the electrical connector 20 and the electrode 11 through the bonding layer 30, the X element in the bonding layer 30 will diffuse into the electrode 11, and the atomic percentage of the X element diffused in the electrode 11 directly affects the structure of the intermetallic compound formed in the electrode 11. If the atomic percentage of X in the electrode 11 is too small, a stable intermetallic compound cannot be formed in the portion of the electrode 11 that intersects with the bonding layer 30, and the electrode 11 and the bonding layer 30 cannot form a stable connection structure, and thus the connection requirements of the electrode 11 and the bonding layer 30 cannot be met. If the atomic percentage of X in the electrode 11 is too large, too many intermetallic compounds will be formed in the electrode 11, which will easily cause brittle fracture problems in the portion of the electrode 11 that intersects with the bonding layer 30, and will also affect the connection performance of the electrode 11 and the bonding layer 30.

[0060] To this end, in the present application, the atomic percentage of X in the electrode 11 is set between 1At% and 9At%, so that the electrode 11 forms a stable and dense intermetallic compound layer 101 at the junction with the bonding layer 30, while avoiding the brittle fracture problem of the intermetallic compound formed in the electrode 11, thereby ensuring the connection performance between the electrical connector 20 and the electrode 11.

[0061] In some embodiments, within the diffusion depth range of X, the number of atoms of X in the electrode is 0.03 to 0.1 times the number of atoms of Y. For example, the number of atoms of X in the electrode is 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1 times the number of atoms of Y. At this time, the diffusion amount of X is appropriate, which is conducive to the formation of a benign and stable intermetallic compound between X and Y at the interface between the electrode and the bonding layer.

[0062] like Figure 8 As shown, Figure 8 The left figure shows a SEM image of the connection structure of the bonding layer 30 and the electrode 11, and the right figure shows a schematic diagram of the distribution of each element in the connection structure of the bonding layer 30 and the electrode 11. Optionally, an intermetallic compound layer 101 is formed between the bonding layer 30 and the electrode 11, the intermetallic compound layer 101 has a first region S1, the bonding layer 30 has a second region S2 adjacent to the first region S1, and the X content in the first region S1 is higher than the X content in the second region S2.

[0063] It is understandable that the bonding layer 30 includes metal particles, organic matter, etc., and the distribution of the X element in the bonding layer 30 is not completely continuous and uniform due to the presence of organic matter and structural voids. When the bonding layer 30 and the electrode 11 are interconnected, the X element in the bonding layer 30 will diffuse and migrate from the bonding layer 30 to the electrode 11 in the longitudinal direction. If the X element diffuses only in the longitudinal direction, the position where the organic matter or structural void exists in the bonding layer 30 lacks the X element that can migrate. Furthermore, the X element is ensured to be continuously distributed at the interface between the bonding layer 30 and the electrode 11 by the lateral diffusion migration of the X element at the interface between the bonding layer 30 and the electrode 11. That is, the formed intermetallic compound layer 101 has a first region S1, the bonding layer 30 has a second region S2 adjacent to the first region S1, and the X content in the first region S1 is higher than that in the second region S2, so that a continuous and uniform intermetallic compound layer 101 can be formed at the interface between the bonding layer 30 and the electrode 11, and the X elements in different regions of the intermetallic compound layer 101 can be evenly distributed, thereby ensuring the connection performance between the bonding layer 30 and the electrode 11 at different positions.

[0064] In some embodiments, Figure 4Figure c shows a schematic diagram of the distribution of lead elements in the electrode; the electrode 11 also includes lead (Pb) elements. In this application, the electrode 11 is made to contain lead elements through the design of process temperature and time. Since lead is a high-density, soft and stable metal that is not easily oxidized, when the electrode 11 and the bonding layer 30 are interconnected, the oxidation resistance of the intermetallic compound formed by the interface fusion of the electrode 11 and the bonding layer 30 can be increased. At the same time, the mechanical strength of the formed intermetallic compound layer 101 can also be improved. In addition, the surface tension and viscosity at the bonding interface can be reduced, and the wettability and fluidity can be improved, which is conducive to the formation of a stable and dense intermetallic compound layer 101 between the electrode 11 and the bonding layer 30.

[0065] In other embodiments, Figure 4 Figure d in the figure shows a schematic diagram of the distribution of bismuth elements in the electrode; the electrode 11 also includes bismuth (Bi) elements. In the present application, the electrode 11 includes bismuth elements through the process temperature and time design, so that when the electrode 11 is interconnected with the bonding layer 30, the melting point of the material at the connection position can be reduced, and the low-temperature interconnection process is used to interconnect the electrode 11 and the bonding layer 30, thereby reducing the production cost; at the same time, the formed intermetallic compound layer 101 includes bismuth elements, which also helps to increase the hardness of the intermetallic compound layer 101, thereby improving the connection strength between the electrode 11 and the bonding layer 30.

[0066] It is understandable that the bonding layer 30 may include lead and bismuth. When the electrode 11 and the bonding layer 30 are interconnected by welding or other methods, the lead and bismuth in the bonding layer 30 will diffuse and migrate into the electrode 11, which can improve the wettability and fluidity of the bonding layer 30 material on the electrode 11, and also help to promote the formation of a relatively stable and dense intermetallic compound layer 101 at the interface between the electrode 11 and the bonding layer 30, thereby improving the connection strength and conductivity between the electrode 11 and the electrical connector 20.

[0067] Optionally, the content of X in the electrode 11 is greater than the content of lead, the content of bismuth, or the total content of lead and bismuth. Wherein, X is tin. In this case, when the electrode 11 and the bonding layer 30 are interconnected, a relatively stable and dense intermetallic compound layer 101 can be formed at the interface between the electrode 11 and the bonding layer 30, thereby improving the bonding strength between the electrode 11 and the bonding layer 30.

[0068] like Figure 4 As shown, based on Figure 4 It can be seen from Figures b, c, and d that the bright spots representing the tin element are more densely distributed, that is, the tin content in the electrode is greater than the lead content, the bismuth content, or the total content of lead and bismuth.

[0069] In some embodiments, within the diffusion depth range of X, the total mass percentage of lead and bismuth in the electrode 11 is: 0.5Wt%-2Wt%. Specifically, the total mass percentage of lead and bismuth in the electrode 11 can be set to: 0.5Wt%, 0.8Wt%, 1.0Wt%, 1.5Wt%, 1.7Wt%, 2Wt%, etc.

[0070] It is understandable that if the total mass percentage of lead and bismuth in the electrode 11 is too small, it will affect the formation of the intermetallic compound structure in the electrode 11. If the total mass percentage of lead and bismuth is too large, although it can promote the formation of intermetallic compounds at the junction of the electrode 11 and the bonding layer 30, excessive content of lead and bismuth will increase the brittleness of the formed intermetallic compound, which is easy to cause brittle fracture at the interface between the electrode 11 and the bonding layer 30, which will affect the connection performance between the electrode 11 and the bonding layer 30.

[0071] To this end, in the embodiment of the present application, the total mass percentage of lead and bismuth in the electrode 11 is set between 0.5Wt% and 2Wt% to control the content of lead and bismuth in the electrode 11 within a reasonable range, thereby ensuring that a stable intermetallic compound can be formed at the junction of the electrode 11 and the bonding layer 30; and avoiding the problem of brittle fracture of the intermetallic compound formed due to excessive lead and bismuth, thereby ensuring the connection performance of the electrode 11 and the electrical connector 20.

[0072] In some embodiments, within the diffusion depth range of X, the total atomic percentage of lead and bismuth in the electrode 11 is: 0.1At%-1.5At%. Specifically, the total atomic percentage of lead and bismuth in the electrode 11 can be set to: 0.1At%, 0.5At%, 0.8At%, 1.0At%, 1.3At%, 1.5At%, etc.

[0073] In the present application, the total atomic percentage of lead and bismuth in the electrode 11 is controlled within a reasonable range to ensure that the electrode 11 can form a stable intermetallic compound at the junction with the bonding layer 30; at the same time, the brittle fracture problem of the intermetallic compound formed due to excessive lead and bismuth is avoided, thereby ensuring the connection performance between the electrode 11 and the electrical connector 20.

[0074] In some embodiments, within the diffusion depth range of X, the total number of lead and bismuth atoms in the electrode is 0.0065 times to 0.015 times the number of atoms of Y. For example, the total number of lead and bismuth atoms in the electrode is 0.0065 times, 0.0070 times, 0.0078 times, 0.008 times, 0.009 times, 0.010 times, 0.012 times, 0.013 times, 0.014 times, 0.015 times the number of atoms of Y. At this time, the lead and bismuth elements can better assist the X atoms and the Y atoms to quickly form a benign intermetallic compound at the interface. The detection method of the atomic percentage in the electrode 11 can refer to the detection method of the mass percentage of X in the above-mentioned electrode.

[0075] In some embodiments, the X content in the electrode 11 is greater than the Y content in the bonding layer 30 .

[0076] It can be understood that it is relatively easier for the X element to diffuse into the electrode 11 than for the Y element to diffuse into the bonding layer 30. Therefore, by making the X content in the electrode 11 greater than the Y content in the bonding layer 30, while ensuring that a relatively stable intermetallic compound layer 101 can be formed between the electrode 11 and the bonding layer 30, the difficulty of the interconnection process can be appropriately reduced, thereby reducing the processing cost.

[0077] In other embodiments, the diffusion depth of X in the electrode 11 is greater than the diffusion depth of Y in the bonding layer 30. In the present application, by setting the diffusion depth of X in the electrode 11 to be greater than the diffusion depth of Y in the bonding layer 30, even if the diffusion degree of the X element in the electrode 11 is greater than the diffusion degree of the Y element in the bonding layer 30, it can ensure that a relatively stable intermetallic compound layer 101 is formed between the electrode 11 and the bonding layer 30, and at the same time, it can reduce the process difficulty, thereby reducing the processing cost.

[0078] Optionally, the diffusion depth of Y in the bonding layer 30 is H3, and the thickness of the bonding layer 30 is H4, satisfying: H3 / H4≥30%. Specifically, H3 / H4 can be set to 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, etc.

[0079] In some embodiments, Figure 5 As shown, Figure 5 A schematic diagram of the distribution structure of each element in the bonding layer of an embodiment of the present application is shown. Figure 5 Figure e in FIG. 1 shows the distribution of silver elements in the bonding layer 30 , and the bright spots in the figure represent the distribution of silver elements in the bonding layer 30 .

[0080] In the embodiment of the present application, the ratio H3 / H4 of the diffusion depth of Y in the bonding layer 30 to the total thickness of the bonding layer 30 is set to be greater than or equal to 30% to ensure that the Y element is fully diffused in the bonding layer 30. In this way, it is convenient for the bonding layer 30 to form a stable intermetallic compound at the junction with the electrode 11, thereby ensuring the connection performance between the bonding layer 30 and the electrode 11.

[0081] It is understandable that if the H3 / H4 is less than 30%, the diffusion depth of Y in the bonding layer 30 is shallow, that is, the Y element in the electrode 11 does not diffuse sufficiently into the bonding layer 30, which will affect the formation of intermetallic compounds in the bonding layer 30 and is not conducive to the connection and fixation of the electrode 11 and the electrical connector 20.

[0082] In some embodiments, the diffusion depth of Y in the bonding layer 30 can also be detected by using an energy spectrometer, and the connection structure between the electrical connector 20 and the electrode 11 is selected as a test sample, and the cross section of the test sample is scanned and analyzed by using an energy spectrometer. When the bonding layer 30 is detected and analyzed, the interface between the electrode 11 and the bonding layer 30 is used as the starting point, and the scanning analysis is performed from bottom to top along a straight line, so that the following can be obtained: Figure 7 The diffusion depth variation curve of the silver element in the bonding layer 30 is shown.

[0083] In some embodiments, the diffusion depth of Y in the bonding layer 30 is 0.4 μm-1.4 μm. Specifically, the diffusion depth of Y in the bonding layer 30 can be set to 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, 1.3 μm, 1.4 μm, etc.

[0084] In the embodiment of the present application, by setting the diffusion depth of the Y element in the bonding layer 30 between 0.4μm and 1.4μm, it is possible to ensure that a relatively stable intermetallic compound layer 101 of a certain thickness can be formed between the electrode 11 and the bonding layer 30, while ensuring the connection performance between the bonding layer 30 and the electrode 11.

[0085] It is understandable that if the diffusion depth of Y in the bonding layer 30 is less than 0.4 μm, the diffusion degree of the Y element in the electrode 11 into the bonding layer 30 is insufficient, and the bonding layer 30 cannot form a relatively stable intermetallic compound at the junction with the electrode 11, and thus cannot meet the connection requirements between the bonding layer 30 and the electrode 11. If the diffusion depth of Y in the bonding layer 30 is greater than 1.4 μm, that is, the diffusion degree of the Y element into the bonding layer 30 is high, the intermetallic compound layer 101 formed between the bonding layer 30 and the electrode 11 is too thick. Due to the high brittleness of the intermetallic compound layer 101, the too thick intermetallic compound layer 101 is prone to brittle fracture during use, which in turn affects the connection performance between the electrode 11 and the electrical connector 20.

[0086] In some embodiments, within the diffusion depth range of Y, the mass percentage of Y in the bonding layer 30 is 2wt%-7wt%. Specifically, the mass percentage of Y in the bonding layer 30 can be set to 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, etc.

[0087] In the embodiment of the present application, a reasonable range of the mass percentage of Y in the bonding layer 30 is set so that a stable and dense intermetallic compound layer 101 can be formed between the bonding layer 30 and the electrode 11, while avoiding the brittle fracture problem of the intermetallic compound layer 101 formed in the bonding layer 30, thereby ensuring the connection performance between the bonding layer 30 and the electrode 11.

[0088] In some embodiments, within the diffusion depth range of Y, the atomic percentage of Y in the bonding layer 30 is 3At%-8At%. Specifically, the atomic percentage of Y in the bonding layer 30 can be set to 3At%, 4At%, 5At%, 6At%, 7At%, 8At%, etc.

[0089] In the embodiment of the present application, the atomic percentage of Y in the bonding layer 30 is set between 3At% and 8At%, so that a stable and dense intermetallic compound layer 101 can be formed between the bonding layer 30 and the electrode 11, and at the same time, the brittle fracture problem of the intermetallic compound layer 101 formed in the bonding layer 30 can be avoided, thereby ensuring the connection performance between the bonding layer 30 and the electrode 11.

[0090] In some embodiments, within the diffusion depth range of Y, the number of atoms of Y in the bonding layer is 0.05 to 0.17 times the number of atoms of X. For example, the number of atoms of Y in the bonding layer is 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17 times the number of atoms of X. At this time, the diffusion depth and diffusion amount of the Y element are sufficient to form a benign and stable intermetallic compound with the X element at the interface.

[0091] Alternatively, if Figure 5 As shown, the bonding layer 30 includes a first bonding portion 31 and a second bonding portion 32, the first bonding portion 31 is connected to the electrode 11, and the second bonding portion 32 is arranged on the side of the first bonding portion 31 away from the electrode 11; wherein the Y content in the first bonding portion 31 is greater than the Y content in the second bonding portion 32.

[0092] In the embodiment of the present application, by making the Y content in the first bonding portion 31 in the bonding layer 30 greater than the Y content in the second bonding portion 32, it is beneficial for the first bonding portion 31 to form a benign intermetallic compound at the junction with the electrode 11, thereby ensuring the bonding strength and conductivity between the electrical connector 20 and the electrode 11, while reducing the generation of malignant intermetallic compounds.

[0093] It can be understood that the Y content may include the mass percentage content or atomic percentage content of the Y element in the bonding layer 30. Further, the Y content in this embodiment and the following embodiments refers to the atomic percentage content of the Y element.

[0094] Optionally, the thickness of the first bonding portion 31 is greater than or equal to 0.1 μm and less than or equal to 2 μm in a direction perpendicular to the surface of the battery cell 10. Specifically, the thickness of the first bonding portion 31 can be set to: 0.1 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.7 μm, 2 μm, etc.

[0095] In the embodiment of the present application, the thickness of the first bonding portion 31 is set between 0.1 μm and 2 μm to ensure that the Y element in the electrode 11 is fully diffused into the bonding layer 30, so that the Y element can be combined with the metal element in the first bonding portion 31 to form an intermetallic compound in the first bonding portion 31, thereby forming a relatively stable and dense intermetallic compound layer 101 between the bonding layer 30 and the electrode 11, thereby improving the bonding strength and conductivity between the electrical connector 20 and the electrode 11.

[0096] In some embodiments, the method for detecting the intermetallic compound layer 101 includes: selecting a connection structure between the electrical connector 20 and the electrode 11 on the battery cell 10, cutting the connection structure to obtain a test sample, and then using a scanning electron microscope to take a SEM image of the cross-sectional structure of the test sample, as shown in FIG. Figure 2 As shown, in the SEM image, the electrode 11 and the bonding layer 30 have different display colors, the electrode 11 has a darker color, the bonding layer 30 has a lighter color, and the intermetallic compound layer 101 has a color between the electrode 11 and the bonding layer 30. Furthermore, the thickness of the intermetallic compound layer 101 can be detected using the line scanning mode of the scanning electron microscope.

[0097] Specifically, along the surface direction perpendicular to the cell, the thickness of the intermetallic compound layer 101 is 0.5 μm-4 μm. Specifically, the thickness of the intermetallic compound layer 101 can be set to 0.5 μm, 0.8 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, etc. By controlling the thickness range of the intermetallic compound layer 101 formed between the electrode 11 and the bonding layer 30, it is possible to ensure that the electrode 11 and the bonding layer 30 form a stable connection structure through the intermetallic compound layer 101, and avoid the problem of easy brittle fracture due to excessive thickness of the intermetallic compound layer 101.

[0098] In some embodiments, the diffusion depth of X in the electrode 11 is greater than the thickness of the intermetallic compound layer 101. In the present application, by making the diffusion depth of X in the electrode 11 greater than the thickness of the intermetallic compound layer 101, it is ensured that the X element can fully diffuse into the electrode 11, thereby ensuring that a stable intermetallic compound can be formed in the interface between the electrode 11 and the bonding layer 30, and improving the bonding reliability of the electrode 11 and the bonding layer 30.

[0099] In some embodiments, the diffusion depth of Y in the bonding layer 30 is greater than the thickness of the intermetallic compound layer 101. In the present application, by making the diffusion depth of Y in the bonding layer 30 greater than the thickness of the intermetallic compound layer 101, it is ensured that the Y element can fully diffuse into the bonding layer 30, thereby ensuring that a stable intermetallic compound can be formed in the bonding layer 30.

[0100] In some embodiments, the electrode 11 further includes lead, and the diffusion depth of the lead in the electrode 11 is greater than the thickness of the intermetallic compound layer 101 .

[0101] In the present application, the diffusion depth of lead in the electrode 11 is made greater than the thickness of the intermetallic compound layer 101, that is, it is ensured that the lead element can fully diffuse into the electrode 11, thereby ensuring stable intermetallic compounds in the electrode 11, and at the same time, ensuring the mechanical strength of the formed intermetallic compounds.

[0102] In some embodiments, the electrode 11 further includes bismuth, and the diffusion depth of the bismuth in the electrode 11 is greater than the thickness of the intermetallic compound layer 101 .

[0103] In the present application, the diffusion depth of bismuth in the electrode 11 is made greater than the thickness of the intermetallic compound layer 101, that is, it is ensured that the bismuth element can fully diffuse into the inside of the electrode 11, thereby ensuring a stable intermetallic compound in the electrode 11. At the same time, the bismuth element can lower the melting point of the electrode materials when interconnecting, thereby facilitating the interconnection operation.

[0104] Optionally, from the surface of the electrode 11 away from the battery cell 10 toward the battery cell 10 , the X content and the Y content in different regions at the same depth position in the electrode 11 are proportional.

[0105] It can be understood that the electrode 11 includes metal particles and organic matter, and in the process of diffusion of the X element in the bonding layer 30 into the electrode 11, the area with metal particles is more conducive to the diffusion of the X element than the area without metal particles or with smaller metal particles. Therefore, the X content and the Y content in different areas at the same depth position in the electrode 11 are proportional, which is conducive to the combination of the X metal and the Y metal.

[0106] In some embodiments, the electrode includes a metal group, and there is a non-metallic material between adjacent metal groups. The non-metallic material is embedded and filled in the gap between the metal groups. In this case, the electrode can be made of low-temperature metal slurry, and the battery cell and the metal group in the electrode are reliably bonded and well conductive through non-metallic materials, such as organic matter, additives, etc. The presence of non-metallic materials makes the intermetallic compounds formed between the bonding layer and the electrode relatively small and dispersed, thereby affecting the bonding reliability between the bonding layer and the electrode.

[0107] In actual production, by adjusting the temperature, time and other methods, more X elements in the bonding layer are diffused into the electrode, and more Y elements in the electrode are diffused into the bonding layer, so as to achieve the interaction between X elements and Y elements, and enhance the bonding reliability between the low-temperature electrode and the bonding layer. At the same time, the diffusion depth of X elements can be adjusted so that there is a gap between X elements and the surface of the battery cell under the electrode, that is, there is no contact between X elements and the battery cell, thereby ensuring the efficiency of the battery cell.

[0108] Optionally, an embodiment of the present application further provides a photovoltaic system, comprising the photovoltaic assembly in the above embodiment.

[0109] In the embodiment of the present application, the surface of the battery cell 10 is provided with an electrode 11, so that the electrical connector 20 is connected to the electrode 11, and the electrode 11 collects the carriers generated by the battery cell 10, and the electrical connector 20 collects and guides the battery cell 10. Furthermore, by making the X element in the bonding layer 30 at least partially diffuse into the electrode 11, and making the Y element in the electrode 11 at least partially diffuse into the bonding layer 30, the electrical connector 20 and the electrode 11 are enabled to form an intermetallic compound at the bonding interface, so as to ensure the structural strength of the connection interface between the electrical connector 20 and the electrode 11, and ensure that the bonding force between the bonding layer 30 and the electrode 11 is greater than or equal to 0.5N / mm 2 This is beneficial to improving the connection performance and conductivity between the electrical connector 20 and the electrode 11, thereby improving the performance of the photovoltaic module.

[0110] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0111] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A photovoltaic module, characterized in that: include: Cells, bonding layers and electrical connectors; The surface of the battery cell is provided with an electrode, and the electrical connector is fixed and conductively connected to the electrode through the bonding layer; The electrode at least includes X, and the bonding layer at least includes Y, X is a metal element in the bonding layer, and Y is a metal element in the electrode.

2. The photovoltaic module according to claim 1, characterized in that: The photovoltaic module meets at least one of the following conditions: A. The electrode comprises a first electrode portion and a second electrode portion, the first electrode portion is connected to the bonding layer, and the second electrode portion is located on a side of the first electrode portion away from the bonding layer; wherein the X content in the first electrode portion is greater than the X content in the second electrode portion; B. The X is tin.

3. The photovoltaic module according to claim 2, characterized in that: Along a direction perpendicular to the surface of the battery cell, a thickness of the first electrode portion is greater than or equal to 0.2 μm and less than or equal to 4 μm.

4. The photovoltaic module according to claim 2, characterized in that: The X content in the electrode tends to decrease from the first electrode portion to the second electrode portion.

5. The photovoltaic module according to claim 1, characterized in that: The photovoltaic module meets at least one of the following conditions: C. Along the direction perpendicular to the surface of the cell, the diffusion depth of X in the electrode is H1, the thickness of the electrode is H2, and the following conditions are satisfied: H1 / H2≥50%; D. The diffusion depth of X in the electrode is: 2 μm-5 μm; E. Within the diffusion depth range of X, the mass percentage of X in the electrode is: 2Wt%-10Wt% or the atomic percentage of X in the electrode is: 1At%-9At%; F. Within the diffusion depth range of X, the number of X atoms in the electrode is 0.03 to 0.1 times the number of Y atoms.

6. The photovoltaic module according to claim 1, characterized in that: An intermetallic compound layer is formed between the bonding layer and the electrode. The intermetallic compound layer has a first region. The bonding layer has a second region adjacent to the first region. The X content in the first region is higher than the X content in the second region.

7. The photovoltaic module according to claim 1, characterized in that: The electrode also includes lead and / or bismuth.

8. The photovoltaic module according to claim 7, characterized in that: The content of X in the electrode is greater than the content of lead, the content of bismuth or the total content of lead and bismuth.

9. The photovoltaic module according to claim 7, characterized in that: The photovoltaic module meets at least one of the following conditions: G. Within the diffusion depth range of X, the total mass percentage of lead and bismuth in the electrode is: 0.5Wt%-2Wt% or the total atomic percentage of lead and bismuth in the electrode is: 0.1At%-1.5At%; H. Within the diffusion depth range of X, the total number of lead and bismuth atoms in the electrode is 0.0065 to 0.015 times the number of atoms of Y.

10. The photovoltaic module according to any one of claims 1 to 9, characterized in that: The photovoltaic module meets at least one of the following conditions: I. The X content in the electrode is greater than the Y content in the bonding layer; J. The diffusion depth of X in the electrode is greater than the diffusion depth of Y in the bonding layer; K. Y is at least one of silver, copper, aluminum and nickel.

11. The photovoltaic module according to any one of claims 1 to 9, characterized in that: The photovoltaic module meets at least one of the following conditions: L. The diffusion depth of Y in the bonding layer is H3, the thickness of the bonding layer is H4, and the following conditions are satisfied: H3 / H4 ≥ 30%; M. The diffusion depth of Y in the bonding layer is: 0.4 μm-1.4 μm; N. Within the diffusion depth range of Y, the mass percentage of Y in the bonding layer is: 2Wt%-7Wt% or the atomic number percentage of Y in the bonding layer is: 3At%-8At%; O. Within the diffusion depth range of Y, the number of atoms of Y in the bonding layer is 0.05 to 0.17 times the number of atoms of X.

12. The photovoltaic module according to any one of claims 1 to 9, characterized in that: The bonding layer includes a first bonding portion and a second bonding portion, the first bonding portion is connected to the electrode, and the second bonding portion is arranged on a side of the first bonding portion away from the electrode; wherein the Y content in the first bonding portion is greater than the Y content in the second bonding portion.

13. The photovoltaic module according to claim 12, characterized in that: Along a direction perpendicular to the surface of the battery cell, a thickness of the first bonding portion is greater than or equal to 0.1 μm and less than or equal to 2 μm.

14. The photovoltaic module according to any one of claims 1 to 9, characterized in that: The photovoltaic module meets at least one of the following conditions: T. The diffusion depth of X in the electrode is greater than the thickness of the intermetallic compound layer; U. The diffusion depth of Y in the bonding layer is greater than the thickness of the intermetallic compound layer; V. The electrode further comprises lead, and the diffusion depth of the lead in the electrode is greater than the thickness of the intermetallic compound layer; W. the electrode further includes bismuth, and the diffusion depth of the bismuth in the electrode is greater than the thickness of the intermetallic compound layer; X. The bonding force between the bonding layer and the electrode is greater than or equal to 0.5 N / mm 2 .

15. The photovoltaic module according to claim 1, characterized in that: In the direction from the surface of the electrode away from the battery cell to the battery cell, the X content and the Y content in different regions at the same depth position in the electrode are proportional.

16. The photovoltaic module according to claim 1, characterized in that: The electrode is selected from a metal electrode combining a sheet and a powder, a metal electrode combining a sphere and a powder, or a nano-electrode.

17. The photovoltaic module according to claim 1, characterized in that: The electrode includes metal groups, and non-metallic materials are disposed between adjacent metal groups.

18. A photovoltaic system, characterized in that: Comprising the photovoltaic module according to any one of claims 1 to 17.

Images