Welding bottom plate and welding method

Abstract

The invention relates to a welding bottom plate and a welding method. The welding bottom plate comprises a base, a boss and a lifting table, the boss is arranged on one side of the base in the thickness direction and extends in the first direction, the boss is provided with a first end, a second end and a bearing face, the first end and the second end are oppositely arranged in the first direction, the bearing face is connected between the first end and the second end, and the bearing face is used for bearing a welding strip; and in the thickness direction of the base, compared with the first end and the second end, the bearing surface is sunken towards one side close to the base. The lifting table is arranged on the base in an extending mode in the second direction and used for supporting the battery piece, and the lifting table is provided with a working position and can move in the third direction so as to be close to or away from the working position; under the condition that the lifting table is located at the working position, the battery piece abuts against the welding strip. Wherein the first direction, the second direction and the third direction intersect pairwise.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic modules, and in particular to a welding base plate and a welding method. Background Art

[0002] Photovoltaic cells are the power generation units in photovoltaic modules. They collect and transmit current through the grid electrodes on the surface. When welding in series, the welding tape needs to be pressed on the position of the grid electrodes to form a complete series circuit. Finally, after stacking and laminating, they are packaged with materials such as glass, backplane, and film to form photovoltaic modules. When welding in series, the automatic welding machine needs to use welding tape to weld the single cells together to ensure that each welded cell can work normally.

[0003] The welding base plate in the related art is a planar structure, which supports the welding ribbon and the battery cell before welding. However, the welding ribbon on the battery cell welded by the welding base plate in the related art is prone to warping, resulting in welding failure or stress fragmentation of the battery cell. Summary of the invention

[0004] Based on this, a welding base plate and a welding method are provided, so that the battery cell and the welding strip are well welded after welding, and the welding strip is not easy to warp, and the battery cell is not easy to break, and has a better welding effect.

[0005] According to one aspect of the present application, a welding base plate is provided, the welding base plate comprising:

[0006] Base;

[0007] a boss, which is arranged at one side in the thickness direction of the base and extends along the first direction, the boss having a first end and a second end which are arranged opposite to each other along the first direction, and a bearing surface connected between the first end and the second end, the bearing surface being used to bear the welding strip; along the thickness direction of the base, the bearing surface is recessed toward a side close to the base compared to the first end and the second end; and

[0008] A lifting platform, the lifting platform is arranged on the base in a manner extending along the second direction and used to support the battery cell, the lifting platform has a working position and is configured to be movable along a third direction to approach or move away from the working position; when the lifting platform is in the working position, the battery cell abuts against the welding strip;

[0009] The first direction, the second direction and the third direction intersect each other.

[0010] In one embodiment, a plane perpendicular to the second direction and intersecting the bearing surface is defined as a first reference plane, the bearing surface intersects the first reference plane at a first intersection line, and at least a portion of the first intersection line is an arc line recessed toward the base.

[0011] In one embodiment, a plane perpendicular to the first direction is defined as a second reference plane, the bearing surface intersects with the second reference plane at a second intersection line, and at least a portion of the second intersection line is an arc line recessed toward the base;

[0012] And along the third direction, the size of the bearing surface is smaller than the size of the welding strip.

[0013] In one of the embodiments, a plane perpendicular to the third direction is defined as a third reference plane;

[0014] The first intersection line includes a first convex end point located at the highest point along the second direction, and a first concave point having a maximum interval with the first convex end point along the second direction, and an angle β between a line connecting the first convex end point and the first concave point and the third reference plane satisfies: 0≤β≤5°; and / or

[0015] The second intersection line includes a second convex endpoint located at the highest point along the second direction, and a second concave point which has the largest interval with the second convex endpoint along the second direction, and an angle γ between a line connecting the second convex endpoint and the second concave point and the third reference plane satisfies: 0≤γ≤5°.

[0016] In one of the embodiments, the welding base plate also includes an adsorption member arranged on the base, and the adsorption member is used to adsorb the battery cell; the adsorption member includes an adsorption surface, and when the adsorption member adsorbs the battery cell, the adsorption surface abuts against the battery cell; and the adsorption surface is configured to be able to approach or move away from the base along the second direction.

[0017] In one embodiment, the welding base plate has a working state, and when the welding base plate is in the working state, the adsorbent adsorbs the battery cell, and the adsorption surface approaches the base along the second direction to be in an adsorption position;

[0018] Along the third direction, a distance a between the adsorption position and the carrying surface satisfies: 0 mm ≤ a ≤ 2 mm.

[0019] In one embodiment, the suction member includes a multi-lip suction nozzle, and the multi-lip suction nozzle forms the suction surface toward one side of the battery cell, and the welding base plate also includes a first vacuum driving member, and the first vacuum driving member is connected to the multi-lip suction nozzle to drive the multi-lip suction nozzle to switch between a suction state and a release state; and / or

[0020] The adsorption member includes a suction cup, and the side of the suction cup facing the battery cell forms the adsorption surface. The welding base plate also includes a second vacuum driver and a displacement driver. The second vacuum driver is connected to the suction cup and is used to drive the suction cup to switch between the adsorption state and the relaxation state. The displacement driver is connected between the base and the adsorption member to drive the adsorption member to approach or move away from the base along the second direction.

[0021] In one embodiment, the distance b between the bearing surface of the boss and the top surface of the base facing the boss satisfies: 1mm≤b≤3mm; the dimension c of the boss along the first direction and the dimension d of the boss along the third direction satisfy: 20≤c / d≤100.

[0022] According to another aspect of the present application, a welding method is provided, using the welding base plate described in any of the above embodiments, the welding method comprising:

[0023] Placing the welding strip on the boss in a manner extending along a first direction;

[0024] Placing the battery cell on the lifting platform, and the lifting platform drives the battery cell to approach the base so that the battery cell abuts against the welding strip;

[0025] Weld the battery cells and the welding ribbons to form a battery string;

[0026] After welding is completed, the battery sheet welded with the welding ribbon is removed, and the lifting platform is moved away from the base.

[0027] In one embodiment, the welding base plate further comprises an adsorption member disposed on the base, the adsorption member comprises an adsorption surface, and the step of placing the battery cell on the lifting platform, the lifting platform driving the battery cell close to the base, and making the battery cell abut against the welding ribbon comprises:

[0028] After placing the battery cell on the lifting platform, the battery cell is adsorbed by the adsorbent;

[0029] The lifting platform and the adsorption surface simultaneously approach the base along the second direction, so that the battery cell abuts against the welding strip.

[0030] The bearing surface of the boss of the above-mentioned welding base plate is set concavely toward the side close to the base. It can be understood that the boss is a structure that is concave in the middle and slightly convex at both ends along the first direction. When the welding strip is placed on the boss, it is also placed in a state where the middle is slightly concave and the two ends are slightly convex. In this way, the length of the welding strip can be slightly increased, or the welding strip has a slight redundant length. After the battery cell moves close to the base to abut against the welding strip and is welded and cooled, even if there is thermal expansion and contraction, and the thermal expansion coefficient of the welding strip and the battery cell is different. However, the redundant length of the welding strip is utilized, so that the battery cell can still return to a flat state after being subjected to the tensile force of the welding strip shrinking, and the welding strip will not shrink and warp, so that the battery cell and the welding strip are both in a flat state. It can be seen that the battery cell and the welding strip after welding using the welding base plate of the present application are well welded, and the welding strip is not easy to warp, and the battery cell is not easy to break, and has a good welding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of a welding base plate in one embodiment of the present application.

[0032] Figure 2 Schematic diagram of the structure of the boss in one embodiment of the present application.

[0033] Figure 3 This is a flowchart of the steps of a welding method in one embodiment of the present application.

[0034] Description of Figure Numbers:

[0035] 10. Welding base plate;

[0036] 11. base; 12. boss; 121. bearing surface; 13. lifting platform; 14. adsorption member;

[0037] M1, first reference plane; L1, first intersection line; M2, second reference plane; L2, second intersection line;

[0038] F1, first direction; F2, second direction; F3, third direction. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0040] In the description of the present application, it should be understood that if 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", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0041] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0043] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, 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 implementation method.

[0045] The problem of warping of the solder strip on the cell is a common quality problem in the manufacturing process of photovoltaic modules. It may cause defects such as hidden cracks and broken pieces of the cell, affecting the reliability and yield rate of the module. Common causes of solder strip warping include: abnormal positioning of the welding machine will cause the solder strip to shift, resulting in misalignment and warping of the solder strip; the offset of the main grid line of the cell raw material causes the solder strip and the main grid line to shift after welding, and the solder strip warps after the offset; the temperature is too high and the bending hardness of the solder strip is too large, causing the cell to bend after welding. The main reason for the warping of the solder strip, hidden cracks or broken pieces of the cell is the difference between the thermal expansion coefficients of the solder strip and the cell. The deformation difference between the two during the welding process is different, which causes the solder strip to warp after welding, and the cell is prone to hidden cracks and broken pieces due to the tension of the solder strip.

[0046] The welding base plate in the related art is a planar structure. The welding base plate is used to accommodate the welding strips and battery cells so that the battery cells are in contact with the welding base plate. The welding base plate is provided with components for fixing the battery cells and welding strips. In order to tightly fix the battery cells, the structural height of some of the components is usually slightly higher than the height of the surface of the welding base plate. This can easily cause the battery cells to be lifted up, resulting in poor contact between the battery cells and the welding strips. If the component can fix the battery cells so that they are flush with the surface of the welding base plate, the hard contact between the battery cells and the welding base plate can also easily cause the problem of battery cell fragmentation. In addition, some components are usually only fixed to part of the battery cell in order to have a better contact area between the welding strips and the battery cells. This causes uneven force at various locations on the battery cell, which can easily lead to battery cell fragmentation.

[0047] That is, the welding strips on the battery cells welded by the welding base plate in the related art are prone to warping, resulting in welding failure or stress-induced fragmentation of the battery cells.

[0048] Based on this, the present application provides a welding base plate and a welding method, so that the battery cell and the welding strip are well welded after welding, and the welding strip is not easy to warp, and the battery cell is not easy to break, and has a better welding effect.

[0049] See also Figure 1 As shown, Figure 1The schematic diagram of the structure of the welding base plate 10 in one embodiment of the present application. The welding base plate 10 provided in the present application includes a base 11, a boss 12 and a lifting platform 13. The boss 12 is arranged on one side of the thickness direction of the base 11 and extends along the first direction F1. The boss 12 has a first end and a second end arranged opposite to each other along the first direction F1, and a bearing surface 121 connected between the first end and the second end. The bearing surface 121 is used to bear the welding strip. The welding strip is placed on the boss 12 so that it can be welded after the battery cell is placed later.

[0050] Along the thickness direction of the base 11, the bearing surface 121 is recessed toward the side close to the base 11 compared to the first end and the second end. It can be understood that the boss 12 is a structure that is recessed in the middle and slightly convex at both ends along the first direction F1. When the welding strip is placed on the boss 12, it is also slightly recessed in the middle and slightly convex at both ends. In this way, the length of the welding strip can be slightly increased, or the welding strip has a slight redundant length. After the battery cell moves close to the base 11 to abut against the welding strip and is welded and cooled, even if there is thermal expansion and contraction, and the thermal expansion coefficients of the welding strip and the battery cell are different. However, the redundant length of the welding strip is utilized, so that the battery cell can still return to a flat state after being pulled by the shrinkage of the welding strip, and the welding strip will not shrink and warp, so that the battery cell and the welding strip are both in a flat state.

[0051] The lifting platform 13 is arranged on the base 11 extending along the second direction F2, and is used to support the battery cell. The lifting platform 13 has a working position and is configured to be movable along the third direction F3 to approach or move away from the working position. When the lifting platform 13 is in the working position, the battery cell abuts against the welding strip. In this way, the position of the battery cell can be adjusted by the lifting platform 13. For example, before the battery cell is placed, the lifting platform 13 is first moved away from the working position to the initial position, at which time the support surface at the top of the lifting platform 13 is away from the boss 12 or the welding strip. Then the battery cell is placed on the support surface of the lifting platform 13. At this time, the battery cell will not contact the welding strip, and the position of the battery cell can be adjusted first. After adjusting the position of the battery cell, the lifting platform 13 is lowered to the working position, so that the welding strip contacts the battery cell, and then welding is performed. The battery cell contacts the lifting platform 13 first, which reduces the risk of the position of the welding strip being offset after the battery cell directly contacts the boss 12 and the welding strip, thereby causing the welding strip and the battery cell to be misaligned, which is conducive to improving the welding success rate.

[0052] In some embodiments, when the lifting platform 13 is in the initial position, the support surface at the top of the lifting platform 13 is 0 mm-1 mm higher than the bearing surface of the boss. Here, "higher" means that the distance between the support surface at the top of the lifting platform 13 and the base 11 is greater than the distance between the bearing surface of the boss 12 and the base 11.

[0053] The first direction F1, the second direction F2 and the third direction F3 intersect each other. It can be understood that the extension direction of the boss 12 and the extension direction of the lifting platform 13 can intersect, and are not limited to being perpendicular to each other, so that it can be applicable to the welding of different types of battery cells. In some embodiments, the extension direction of the boss 12 and the extension direction of the lifting platform 13 can be perpendicular to each other, and no excessive restrictions are made here.

[0054] The welding base plate 10 of the present application can reduce the difference in thermal expansion coefficients between the welding strip and the battery cell, as well as the risk of welding strip warping and battery cell fragmentation caused by thermal expansion and contraction. The bearing surface 121 of the boss 12 is recessed toward the side close to the base 11, so that the length of the welding strip is slightly increased, with a small amount of redundant length. After the welding of the welding strip and the battery cell is completed, the redundant length of the welding strip is utilized, so that the battery cell can still return to a flat state after being subjected to the tensile force of the welding strip shrinkage, and the welding strip will not shrink and warp, so that the battery cell and the welding strip are both in a flat state. It can be seen that the battery cell and the welding strip after welding using the welding base plate 10 of the present application are well welded, and the welding strip is not easy to warp, and the battery cell is not easy to fragment, and has a good welding effect.

[0055] In some embodiments, Figure 1 The welding base plate 10 of the present application includes a plurality of bosses 12, and the plurality of bosses 12 are parallel to each other so as to respectively carry a plurality of welding strips in a one-to-one correspondence, so that the battery cell can be welded to the plurality of welding strips at the same time, which is beneficial to improve the welding efficiency.

[0056] In some embodiments, the welding base plate 10 of the present application includes at least two lifting platforms 13, such as Figure 1 In the illustrated embodiment, the welding base plate 10 includes two lifting platforms 13, which are spaced apart along the first direction F1 and parallel to each other, so as to provide stable support for the battery cell and reduce the risk of battery cell cracking due to unstable support.

[0057] In some embodiments, in conjunction with Figure 2 As shown, Figure 2It is a schematic diagram of the structure of the boss 12 in one embodiment of the present application. The plane perpendicular to the second direction F2 and intersecting with the bearing surface 121 is defined as the first reference plane M1. The bearing surface 121 of the boss 12 intersects with the first reference plane M1 at the first intersection line L1, and at least part of the first intersection line L1 is an arc line that is recessed toward the base 11. That is, the first intersection line L1 can be partially recessed toward the base 11, and the rest of the setting is other shapes. For example, part of the first intersection line L1 is a wavy line, so that there are multiple small protrusion structures. During welding, the small protrusion structure can provide a support point for the welding strip placed on the boss 12, improve the abutment strength between the welding strip and the battery cell, and then increase the welding strength of the corresponding small protrusion structure parts of the two. The bearing surface 121 of the boss 12 is recessed toward the side close to the base 11, and at least part of the first intersection line L1 can be an arc line. The specific structure can be designed according to specific needs.

[0058] And it can be understood that there are multiple planes perpendicular to the second direction F2 and intersecting with the bearing surface 121, that is, there are multiple first reference planes M1, and the multiple first reference planes M1 are parallel to each other. Multiple first reference planes M1 intersect with the bearing surface 121 to form multiple first intersection lines L1. In some embodiments, at least a plurality of all first intersection lines L1 are arcs that are recessed toward the base 11. Therefore, the first intersection line L1 is a smooth arc as a whole. When the adsorbent 14 of the present application adsorbs the battery cell so that the battery cell is recessed toward the welding strip on the boss 12, the boss 12 is a smooth arc-shaped recess, which can provide balanced and stable support for the battery cell everywhere, reducing the risk of battery cell fragments.

[0059] And there is an embodiment in which one of all the first intersection lines L1 is a straight line, that is, when the depression depth of the deepest first intersection line L1 on the bearing surface 121 is the same as the depression depth of the deepest second intersection line L2 on the bearing surface 121, at this time, the deepest first intersection line L1 and the deepest second intersection line L2 are both straight lines.

[0060] In some embodiments, continue to refer to Figure 1 and Figure 2As shown, a plane perpendicular to the first direction F1 is defined as a second reference plane M2, the bearing surface 121 intersects with the second reference plane M2 at a second intersection line L2, and at least a portion of the second intersection line L2 is an arc line that is recessed toward the base 11. The bearing surface 121 is in such a recessed state that the welding strip that is provided on the boss 12 extending along the first direction F1 can be restricted by the recess of the bearing surface 121, which is conducive to positioning the welding strip and reduces the risk of welding failure caused by the deviation of the welding strip. And in some embodiments, the second intersection line L2 of the deepest depression along the second direction F2 on the bearing surface 121 is arranged in the middle along the second direction F2, or the depression on the bearing surface 121 is arranged in the middle of the bearing surface 121 along the second direction F2, so as to facilitate the welding strip to be placed in the middle along the second direction F2. In this way, the convex parts of the relatively middle depression parts at both ends of the boss 12 along the second direction F2 can indirectly support the battery cell through the welding strip, so that the boss 12 can provide more balanced support for the battery cell at both ends along the second direction F2, which is conducive to reducing the risk of battery cell fragments. It should be noted that the above-mentioned boss 12 provides support for the battery cell by the boss 12 indirectly providing support for the battery cell through the welding strip.

[0061] In some embodiments, along the third direction F3, the size of the bearing surface 121 is smaller than the size of the welding strip. Avoiding direct contact between the boss 12 and the battery cell helps to reduce the risk of the boss 12 edge abutting against the battery cell, resulting in insufficient contact between the welding strip and the battery cell, and the boss 12 abutting against the battery cell, resulting in the risk of battery cell fragments.

[0062] In some embodiments, see Figure 2 As shown, a plane perpendicular to the third direction F3 is defined as a third reference plane. The first intersection line L1 includes a first convex endpoint located at the highest point along the second direction F2, and a first concave point having a maximum interval with the first convex endpoint along the second direction F2, and an angle β between a line connecting the first convex endpoint and the first concave point and the third reference plane satisfies: 0≤β≤5°. With such a design, the welding strip provided on the bearing surface 121 has a better concave curvature, and when the adsorbent 14 adsorbs the battery cell so that the battery cell and the welding strip are in contact, the battery cell has a better bending curvature, thereby enabling the battery cell and the welding strip to be in contact more fully, which is beneficial to improving the welding strength between the welding strip and the battery cell. At the same time, the bending curvature of the battery cell is appropriate, which reduces the risk of the battery cell being broken into pieces due to bending.

[0063] In some embodiments, continue to refer to Figure 2As shown, the second intersection line L2 includes a second convex end point at the highest point along the second direction F2, and a second concave point with the largest interval with the second convex end point along the second direction F2, and the angle γ between the line connecting the second convex end point and the second concave point and the third reference plane satisfies: 0≤γ≤5°. With such a design, the solder strip provided on the bearing surface 121 has a better concave depth, thereby reducing the risk of solder strip deviation, facilitating more complete contact between the solder strip and the battery cell, and improving the soldering strength between the solder strip and the battery cell.

[0064] In some embodiments, continue to refer to Figure 1 As shown, the welding base plate 10 also includes an adsorption member 14 disposed on the base 11, and the adsorption member 14 is used to adsorb the battery cell. Providing adsorption force for the battery cell, so that the battery cell remains stable during welding, is conducive to improving the success rate of welding. The adsorption member 14 includes an adsorption surface, and when the adsorption member 14 adsorbs the battery cell, the adsorption surface abuts against the battery cell to provide adsorption force to the battery cell. And the adsorption surface is configured to be able to approach or move away from the base 11 along the second direction F2. Therefore, after the adsorption member 14 adsorbs the battery cell, it can drive the battery cell to approach the base 11, so that the battery cell contacts the welding strip disposed on the boss 12, and then welds. It can be understood that the adsorption member 14 can fix the battery cell and keep the battery cell stable, and at the same time, it can also provide a driving force for the battery cell to be recessed toward the welding strip, so that the battery cell is better fitted with the welding strip, which is conducive to improving the welding effect between the battery cell and the welding strip.

[0065] In some embodiments, the welding base plate 10 has a working state and a waiting state, and the welding base plate 10 can switch between the working state and the waiting state. When the welding base plate 10 is in the working state, the adsorption member 14 adsorbs the battery cell, and the adsorption surface moves along the second direction F2 close to the base 11 to the adsorption position, so as to facilitate full contact between the battery cell and the welding strip. It can be understood that the adsorption position is flush with the bearing surface or slightly lower, where slightly lower means that the adsorption position is closer to the base 11 than the bearing surface.

[0066] When the welding base plate 10 is in a waiting state, the adsorption component 14 releases the battery cell, and the adsorption surface moves away from the base 11 along the second direction F2 to a waiting position. During the welding process, the adsorption component 14 first adsorbs the battery cell and places the adsorption surface in the adsorption position. At the same time, the lifting platform 13 moves to the working position. At this time, the welding base plate 10 is in a working state, and the battery cell on the adsorption surface is in contact with the welding ribbon. Then weld the battery cell and the welding ribbon. After welding, the adsorption component 14 releases the battery cell with the welding ribbon and takes away the battery cell with the welding ribbon. After that, the adsorption surface moves to the waiting position, and the lifting platform 13 moves to the initial position. At this time, the welding base plate 10 is in a waiting state, so as to wait for the welding of the next group of welding ribbons and battery cells.

[0067] In some embodiments, along the third direction F3, the distance a between the adsorption position and the carrying surface 121 satisfies: 0mm≤a≤2mm. In this way, the battery cell can have a better bending curvature, so that the battery cell and the welding strip are fully in contact, which is conducive to improving the welding strength between the welding strip and the battery cell. At the same time, the bending curvature of the battery cell is appropriate, which reduces the risk of the battery cell being broken due to bending.

[0068] In some embodiments, the welding base plate 10 includes a plurality of adsorbents 14, and a plurality of adsorbents 14 of all adsorbents 14 are arranged on the base 11 at intervals along the first direction F1 to form an adsorbent group, so as to provide uniform adsorption force for the battery cell along the first direction F1, which is conducive to improving the adsorption stability of the battery cell and reducing the risk of battery cell cracking. In some embodiments, the plurality of adsorbents 14 form at least two adsorbent groups, and at least two adsorbent groups are arranged on the base 11 at intervals along the second direction F2 to provide uniform adsorption force for the battery cell along the second direction F2, which is conducive to improving the adsorption stability of the battery cell and reducing the risk of battery cell cracking.

[0069] In some embodiments, an adsorption member 14 may be further provided on the lifting platform 13 to improve the adsorption strength of the battery cell and improve the stability of the battery cell on the lifting platform 13. In some embodiments, at least two adsorption members 14 are provided on the same lifting platform 13, and at least two adsorption members 14 are provided on the lifting platform 13 at intervals from each other along the second direction to provide uniform adsorption force for the battery cell along the second direction F2.

[0070] In some embodiments, the adsorption member 14 includes a multi-lip suction nozzle, which forms an adsorption surface on one side of the battery cell, and the welding base plate 10 also includes a first vacuum driver, which is connected to the multi-lip suction nozzle to drive the multi-lip suction nozzle to switch between an adsorption state and a relaxation state. It can be understood that when the multi-lip suction nozzle adsorbs the battery cell, the adsorption surface of the multi-lip suction nozzle provides adsorption force for the battery cell, and at the same time, the adsorption surface of the multi-lip suction nozzle can automatically move downward or toward the base 11, and the adsorption surface approaches the base 11 along the second direction F2 to be in the adsorption position, so that the battery cell is recessed toward the base 11 and fits with the battery cell. After the welding is completed, the multi-lip suction nozzle releases the battery cell, and the adsorption surface moves upward or away from the base 11, and the adsorption surface moves away from the base 11 along the second direction F2 to a waiting position.

[0071] In some embodiments, the adsorbent 14 includes a suction cup, and the side of the suction cup facing the battery cell forms an adsorption surface, and the welding base plate 10 also includes a second vacuum driver and a displacement driver. The second vacuum driver is connected to the suction cup and is used to drive the suction cup to switch between the adsorption state and the relaxation state, thereby driving the suction cup to adsorb or release the battery cell. The displacement driver is connected between the base 11 and the adsorbent 14 to drive the adsorbent 14 to move closer to or away from the base 11 along the second direction F2. It can be understood that in this embodiment, after the suction cup adsorbs the battery cell, the displacement driver can be used to drive the suction cup to move closer to the base 11, and the adsorption surface can be closer to the base 11 along the second direction F2 to the adsorption position, thereby driving the battery cell adsorbed by the suction cup to fit with the welding strip, which is convenient for subsequent welding. After the welding is completed, the displacement driver drives the suction cup to drive the battery cell welded with the welding strip to move away from the base 11 to the original position, and the adsorption surface can be away from the base 11 along the second direction F2 to the waiting position.

[0072] In some embodiments, the distance b between the bearing surface 121 of the boss 12 and the top surface of the base 11 facing the boss 12 satisfies: 1mm≤b≤3mm. It can be understood that if the height of the boss 12 is too high, it is easy to cause the gap between the base 11 and the battery cell to be too large, which in turn causes heat loss, resulting in poor welding and the problem of cold welding. The above distance is conducive to making the distance between the bearing surface 121 of the boss 12 and the base 11 within a preferred distance range, thereby reducing the risk of heat loss during welding, which is conducive to reducing the risk of cold welding and improving the welding effect.

[0073] In some embodiments, the dimension c of the boss 12 along the first direction F1 and the dimension d of the boss 12 along the third direction F3 satisfy, or the aspect ratio of the boss 12 satisfies: 20≤c / d≤100. It can be understood that the aspect ratio of the boss 12 satisfies the above range, and can be applied to the welding of battery cells and welding strips of most sizes, and has a wide range of application.

[0074] In some embodiments, the welding base plate 10 further includes a first elastic pad and a second elastic pad, the first elastic pad is disposed on the bearing surface 121, and the second elastic pad is disposed on the lifting platform 13. The material of the first elastic pad and the second elastic pad both includes a high temperature resistant material. In this way, the risk of causing battery cell fragments during the process of the battery cell being adsorbed and concave to a certain arc is reduced, which is conducive to improving the success rate of welding.

[0075] See also Figure 3 As shown, Figure 3 This is a flow chart of the steps of a welding method in one embodiment of the present application. The present application also provides a welding method, which uses the welding base plate 10 in any of the above embodiments to weld different types of battery cells, especially back contact battery cells (BC).

[0076] Welding methods include:

[0077] S1. Provide a battery cell and a plurality of welding strips, and place the welding strips on the boss 12 in a manner extending along the first direction F1. At this time, the welding strips are placed on the bearing surface 121 of the boss 12, and the bearing surface 121 is recessed toward the base 11, so that the welding strips can be limited on the bearing surface 121, and have a better limiting effect.

[0078] S2. Place the battery cell on the lifting platform 13. The lifting platform 13 drives the battery cell close to the base 11 so that the battery cell contacts the welding strip. It can be understood that the initial position of the support surface of the lifting platform 13 for supporting the top of the battery cell is higher than the welding strip on the boss 12. First, place the battery cell on the support surface of the lifting platform 13 in the initial position so that the battery cell will not contact the welding strip. This can be used to adjust the position of the battery cell first, which is conducive to improving the success rate of subsequent welding. Then, the lifting platform 13 is lowered to the working position to facilitate the subsequent welding of the battery cell and the welding strip.

[0079] S3. Solder the battery cell and the welding ribbon. The battery cell and the welding ribbon can be welded through a structure such as a light box.

[0080] S4, after welding is completed, the battery cell with the welding strip is removed, and the lifting platform 13 is moved away from the base 11. In this way, the lifting platform 13 returns to the initial position to facilitate welding of the next battery cell.

[0081] In some embodiments, step S2, placing the battery cell on the lifting platform 13, the lifting platform 13 drives the battery cell close to the base 11, and makes the battery cell abut against the welding strip includes:

[0082] S21, after placing the battery cell on the lifting platform 13, the battery cell is adsorbed by the adsorbent 14. It can be understood that after the battery cell on the lifting platform 13 is properly adjusted or directly placed, the battery cell is adsorbed by the adsorbent 14 to stabilize the position of the battery cell, so as to facilitate the subsequent accurate alignment of the battery cell and the welding ribbon, which is conducive to improving the welding effect.

[0083] S22, the lifting platform 13 and the adsorption surface simultaneously approach the base 11 along the second direction F2, so that the battery cell abuts against the welding strip. At this time, the lifting platform 13 moves from the initial position to the working position, and the adsorption surface moves from the waiting position to the adsorption position, so that the battery cell and the welding strip abut against each other, which is convenient for subsequent welding.

[0084] It can be understood that in the welding method of the present application, before welding, the lifting platform 13 is in the initial position and the adsorption surface is in the waiting position. During welding, first place a plurality of welding strips on a plurality of bosses 12 in one-to-one correspondence, then place the battery cell on the lifting platform 13, and then allow the adsorption component 14 to adsorb the battery cell, and then the lifting platform 13 and the adsorption surface are simultaneously moved along the second direction F2 close to the base 11, so that the lifting platform 13 moves to the working position, and the adsorption surface moves to the adsorption position, so that the battery cell and the welding strip abut each other. After that, the battery cell and the welding strip are welded, cooled, and the welding is completed. After welding is completed, the adsorption component 14 releases the battery cell and removes the battery cell welded with the welding strip. Finally, the lifting platform 13 moves away from the base 11 and returns to the initial position, and the adsorption surface moves away from the base 11 and returns to the waiting position to wait for the welding of the next group of welding strips and battery cells.

[0085] For the welding steps of BC cells, taking the welding between three adjacent cells as an example, after the previous cell is welded using the above steps, the previous cell is translated to one side of the welding base plate 10, and the multiple welding strips on the previous cell that need to be welded on the cell to be welded are placed on multiple bosses 12 respectively, and the multiple welding strips that need to be welded on the cell to be welded and the next cell at the same time are placed on the other multiple bosses 12 respectively. The previous cell and the next cell here are both relative to the cell to be welded. After the corresponding welding strips are placed, the steps of placing the cell, adsorbing the cell, moving the lifting platform 13 and the adsorption surface at the same time, and welding are started according to the above steps to complete the welding of the cell to be welded. Afterwards, the cell to be welded that has been welded is translated to one side of the welding base plate 10, at which time the "cell to be welded" becomes the above-mentioned "previous cell", and the above-mentioned BC cell welding steps are cycled, so as to weld in sequence to form a battery string.

[0086] The above-mentioned embodiments do not limit the type of battery cells and can be applied to a variety of battery cell designs. The present application can select P-type batteries or N-type batteries according to different needs, and apply the designs of the welding base plate 10 and welding methods of the above-mentioned various embodiments to the selected different types of battery cells.

[0087] The types of the cell grid 11 include, but are not limited to, oxide passivated contact cells (Tunnel Oxide Passivated Contact, TOPCon), intrinsic thin film heterojunction cells (Heterojunction with Intrinsic Thin-film, HJT), back contact cells (Back Contact, BC), perovskite cells, etc.

[0088] For TOPCon cells, along the thickness direction, TOPCon cells include metal silver electrodes, front surface silicon nitride passivation layers, boron-doped emitters, N-type base silicon layers, diffused doping layers, ultra-thin silicon oxide, doped polysilicon, silicon nitride, and metal silver electrodes. The back of the cell is composed of an ultra-thin silicon oxide layer (1nm~2nm) and a phosphorus-doped microcrystalline amorphous mixed Si film, which together form a passivation contact structure. This structure can block the recombination of minority carrier holes and increase the open circuit voltage and short circuit current of the cell. The ultra-thin oxide layer allows majority electrons to tunnel into the polysilicon layer while blocking the recombination of minority carrier holes. The good passivation effect of ultra-thin silicon oxide and heavily doped silicon film causes the energy band on the silicon wafer surface to bend, thereby forming a field passivation effect, greatly increasing the probability of electron tunneling, and reducing the contact resistance, which increases the open circuit voltage and short circuit current of the cell, thereby improving the cell conversion efficiency.

[0089] For HJT cells, along the thickness direction, the HJT cells include a front low-temperature silver electrode, a front conductive film, an N-type amorphous silicon film, an intrinsic amorphous silicon film, an N-type base silicon layer, an intrinsic amorphous silicon film, a P-type amorphous silicon film, a back conductive film, and a back low-temperature silver electrode.

[0090] For BC cells, there is no grid line blocking the front of the BC cell, the appearance is more beautiful, and it has the advantages of high conversion efficiency, low attenuation, and good temperature coefficient. Along the thickness direction of the BC cell, the BC cell includes silicon nitride anti-layer, N+ front surface field, N-type base silicon layer, P+ emitter, N+ back field, aluminum oxide passivation layer, silicon nitride anti-reflection layer, and metal silver electrode. BC cells use ion implantation technology to obtain P and N regions with good uniformity and precisely controllable junction depth. There is no grid line blocking the front of the cell, which can eliminate the shading current loss of the metal electrode and realize the maximum utilization of incident photons. The short-circuit current can be increased by about 7% compared with conventional solar cells; due to the back contact structure, there is no need to consider the grid line blocking problem, and the grid line ratio can be appropriately widened, thereby reducing the series resistance and having a high fill factor; the surface passivation and surface light trapping structure can be optimized to obtain a lower front surface recombination rate and surface reflection.

[0091] The welding base plate 10 and the welding method in the above-mentioned embodiments of the present application can be applied to TOPCon cells, HJT cells and BC cells, and can be applied to BC cells in particular. When applied to TOPCon cells, it can combine the advantages of TOPCon cells such as high photoelectric conversion efficiency, low light-induced attenuation, good temperature coefficient and low attenuation rate. When applied to HJT cells, the battery can have the advantages of high conversion efficiency, low temperature coefficient, excellent weak light response, no light decay phenomenon, etc. In particular, when applied to BC cells, it can be beneficial to the design of unobstructed front of the battery cell, which is beneficial to improve the photoelectric conversion efficiency of the battery cell, and can form a battery string without flipping the battery cell. It can be understood that when the present application is applied to the remaining battery cells that require double-sided welding, it is necessary to flip and weld the other side. The risk of fragmentation during the flipping process is relatively large, the operation is cumbersome, and when the side with the solder strip welded faces the suction cup, it is easy to have problems such as inaccurate suction of the suction cup or affect the welding between the solder strip and the battery cell. The single-sided welding of BC batteries does not require turning over, which reduces the risk of fragmentation. Therefore, during the welding process, the welding strips can be welded to two adjacent battery cells in sequence by replacing the battery cells on the welding base plate 10 in sequence, so as to form a battery string conveniently with a high production yield.

[0092] The welding base plate 10 and welding method provided in the present application can greatly improve the welding effect of the welding strip and the battery cell by setting the bearing surface 121 of the boss 12 to be concave toward the side close to the base 11, setting the lifting platform 13 to be able to rise and fall, and setting the adsorbent 14 to be able to adsorb the battery cell and be able to rise and fall. The battery cell with the welding strip formed by welding has better welding quality, the welding strip will not shrink and warp, the battery cell and the welding strip are both in a flat state, the battery cell is not easy to break, and has a better welding effect.

[0093] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0094] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A welding base plate, characterized in that: The welding base plate comprises: Base; a boss, which is arranged at one side in the thickness direction of the base and extends along the first direction, the boss having a first end and a second end which are arranged opposite to each other along the first direction, and a bearing surface connected between the first end and the second end, the bearing surface being used to bear the welding strip; along the thickness direction of the base, the bearing surface is recessed toward a side close to the base compared to the first end and the second end; and A lifting platform, the lifting platform is arranged on the base in a manner extending along the second direction and used to support the battery cell, the lifting platform has a working position and is configured to be movable along a third direction to approach or move away from the working position; when the lifting platform is in the working position, the battery cell abuts against the welding strip; The first direction, the second direction and the third direction intersect each other.

2. The welding base plate according to claim 1, characterized in that: A plane perpendicular to the second direction and intersecting the bearing surface is defined as a first reference plane. The bearing surface intersects the first reference plane at a first intersection line. At least a portion of the first intersection line is an arc line recessed toward the base.

3. The welding base plate according to claim 2, characterized in that: A plane perpendicular to the first direction is defined as a second reference plane, the bearing surface intersects with the second reference plane at a second intersection line, and at least a portion of the second intersection line is an arc line recessed toward the base; And along the third direction, the size of the bearing surface is smaller than the size of the welding strip.

4. The welding base plate according to claim 3, characterized in that: defining a plane perpendicular to the third direction as a third reference plane; The first intersection line includes a first convex end point located at the highest point along the second direction, and a first concave point having a maximum interval with the first convex end point along the second direction, and an angle β between a line connecting the first convex end point and the first concave point and the third reference plane satisfies: 0≤β≤5°; and / or The second intersection line includes a second convex endpoint located at the highest point along the second direction, and a second concave point which has the largest interval with the second convex endpoint along the second direction, and an angle γ between a line connecting the second convex endpoint and the second concave point and the third reference plane satisfies: 0≤γ≤5°.

5. The welding base plate according to claim 1, characterized in that: The welding base plate also includes an adsorption member arranged on the base, and the adsorption member is used to adsorb the battery cell; the adsorption member includes an adsorption surface, and when the adsorption member adsorbs the battery cell, the adsorption surface abuts against the battery cell; and the adsorption surface is configured to be able to approach or move away from the base along the second direction.

6. The welding base plate according to claim 5, characterized in that: The welding base plate has a working state. When the welding base plate is in the working state, the adsorbent adsorbs the battery cell, and the adsorption surface approaches the base along the second direction to be in an adsorption position; Along the third direction, a distance a between the adsorption position and the carrying surface satisfies: 0 mm ≤ a ≤ 2 mm.

7. The welding base plate according to claim 5, characterized in that: The suction member includes a multi-lip suction nozzle, and the multi-lip suction nozzle forms the suction surface on one side facing the battery cell, and the welding base plate also includes a first vacuum driving member, and the first vacuum driving member is connected to the multi-lip suction nozzle to drive the multi-lip suction nozzle to switch between a suction state and a release state; and / or The adsorption member includes a suction cup, and the side of the suction cup facing the battery cell forms the adsorption surface. The welding base plate also includes a second vacuum driver and a displacement driver. The second vacuum driver is connected to the suction cup and is used to drive the suction cup to switch between the adsorption state and the relaxation state. The displacement driver is connected between the base and the adsorption member to drive the adsorption member to approach or move away from the base along the second direction.

8. The welding base plate according to claim 1, characterized in that: A distance b between the bearing surface of the boss and the top surface of the base facing the boss satisfies: 1mm≤b≤3mm; a dimension c of the boss along the first direction and a dimension d of the boss along the third direction satisfy: 20≤c / d≤100.

9. A welding method, characterized in that: Using the welding base plate according to any one of claims 1 to 8, the welding method comprises: Placing the welding strip on the boss in a manner extending along a first direction; Placing the battery cell on the lifting platform, and the lifting platform drives the battery cell to approach the base so that the battery cell abuts against the welding strip; Solder the battery cells and the welding ribbons; After welding is completed, the battery sheet welded with the welding ribbon is removed, and the lifting platform is moved away from the base.

10. The welding method according to claim 9, characterized in that: The welding base plate further comprises an adsorption member disposed on the base, the adsorption member comprises an adsorption surface, and the step of placing the battery cell on the lifting platform, the lifting platform driving the battery cell close to the base, and making the battery cell abut against the welding strip comprises: After placing the battery cell on the lifting platform, the battery cell is adsorbed by the adsorbent; The lifting platform and the adsorption surface simultaneously approach the base along the second direction, so that the battery cell abuts against the welding strip.

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