Cell string repair method, method for preparing replacement cell string, and cell string

Abstract

A cell string repair method, a method for preparing a replacement cell, and a photovoltaic module. The cell string repair method comprises: taking the remaining solder strip connected to an adjacent cell after cutoff as a solder strip to be soldered, placing a replacement cell, soldering a lap-joint position between said solder strip and a second solder strip of the replacement cell, and fixing the replacement cell and the adjacent cell by using an alloy formed by soldering the lap-joint position. Since the melting point of a second solder of the second solder strip is higher than the melting point of a first solder of the solder strip to be soldered, the melting point of the alloy is also higher than the melting point of the first solder, so that using the alloy to fix the replacement cell and the adjacent cell can make the connection between the cells more reliable, and the probability of repair failure of the cell string is reduced.

Description

Battery string repair method, preparation method for replacement battery string, and battery string Technical Field

[0001] The present application relates to the technical field of battery string repair, and in particular to a battery string repair method, a preparation method for a replacement battery string, and a battery string. Background Art

[0002] In a cell string (such as a photovoltaic cell string), solder ribbons are typically used to connect the front side of one cell to the back side of its adjacent cell. When a cell fails and needs to be replaced, the ribbon connecting the failed cell to its adjacent cell is cut, and the failed cell is then replaced with a qualified cell. The solder on the ribbon on the qualified cell is then heated and melted to fuse the solder on the ribbon on the adjacent cell, securing the qualified cell to the adjacent cell.

[0003] However, the inventors of this application have discovered that the solder between the qualified battery cells fixed in the above manner and the adjacent battery cells may re-melt due to the high external temperature, which may cause the battery cells to separate again and lead to the failure of the battery string repair.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to improve the reliability of the connection between battery cells to reduce the probability of failure during repair of battery strings.

[0006] To achieve the above-mentioned objectives, the present invention provides a battery string repair method, a method for preparing a replacement battery string, and a battery string.

[0007] In a first aspect, the present application provides a battery string repair method, comprising:

[0008] Cutting off the first welding ribbon between the faulty battery cell and its adjacent battery cell in the battery string to be repaired, and using the remaining welding ribbon connected to the adjacent battery cell after cutting off as the welding ribbon to be welded, wherein the surface of the first welding ribbon is covered with a first solder;

[0009] Remove the faulty battery cell and place a replacement battery cell in the corresponding removal position, wherein the replacement battery cell is provided with a second solder strip, the surface of the second solder strip is covered with a second solder, and the melting point of the second solder is higher than the melting point of the first solder;

[0010] The welding strip to be welded is overlapped with the second welding strip, and the overlapping portion of the welding strip to be welded and the second welding strip is welded. The alloy formed by welding the overlapping portion fixes the replacement battery cell and the adjacent battery cell.

[0011] Optionally, the area of ​​the alloy does not exceed the prepared overlap area.

[0012] Optionally, the melting point of the alloy formed by the first solder and the second solder at the overlapping portion is higher than the temperature of the lamination process of the battery cell.

[0013] Optionally, cutting off the first welding ribbon between the faulty cell and its adjacent cell in the cell string to be repaired includes:

[0014] Determine a first truncation position on the first welding strip between the faulty cell and the first adjacent cell, and determine a second truncation position on the first welding strip between the faulty cell and the second adjacent cell, wherein the distance between the first truncation position and the long side of the faulty cell is a first length, the distance between the second truncation position and the long side of the faulty cell is a second length, and the second length does not exceed the first length;

[0015] The first welding strips between the faulty cell and the first adjacent cell and the second adjacent cell are cut off along the first cutting position and the second cutting position respectively.

[0016] Optionally, the first solder is any one of the following:

[0017] The first solder is a ternary alloy of tin, lead, and bismuth, and the mass percentage of bismuth in the first solder is greater than or equal to 1% and less than or equal to 30%;

[0018] The first solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the first solder is greater than 0% and less than or equal to 5%.

[0019] Optionally, the second solder is any one of the following:

[0020] The second solder is a ternary alloy of tin, lead, and bismuth, and the mass percentage of bismuth in the second solder is at least less than 30%;

[0021] The second solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the second solder is at least less than 5%;

[0022] The second solder is a ternary alloy of tin, lead and silver, and the mass percentage of silver in the second solder is greater than 0% and less than or equal to 5%;

[0023] The second solder is a tin-lead binary alloy, and the mass percentage of lead in the second solder is greater than 20% and less than or equal to 50%.

[0024] Optionally, welding the overlapping portion between the welding strip to be welded and the second welding strip includes any one or a combination of the following methods:

[0025] Soldering iron heating method, infrared heating method, hot air heating method, electromagnetic heating method, laser welding method.

[0026] Optionally, the length of the overlapping portion is not shorter than 1 mm, and the length of the alloy is not shorter than 1 mm.

[0027] Optionally, the end of the alloy away from the adjacent cell does not exceed the end of the connecting line associated with the outermost sub-grid on the adjacent cell away from the adjacent cell in the direction perpendicular to the long side inward of the adjacent cell.

[0028] In a second aspect, the present application provides a method for preparing a replacement battery cell, comprising:

[0029] providing a battery substrate;

[0030] A replacement solder strip is provided on the battery substrate, wherein the surface of the replacement solder strip is covered with replacement solder having a melting point higher than the melting point of the solder covering the surface of the solder strip on the faulty battery cell to be replaced by the replacement battery cell.

[0031] Optionally, the replacement solder and the solder form an alloy, and the area of ​​the alloy does not exceed the prepared overlapping area.

[0032] In a third aspect, the present application provides a battery string, comprising:

[0033] A first battery cell has a first solder strip, and a surface of the first solder strip is covered with a first solder;

[0034] A second battery cell has a second solder strip, and a surface of the second solder strip is covered with a second solder;

[0035] The first battery cell and the second battery cell are connected by overlapping the first solder strip and the second solder strip, and the overlapping portion has an alloy of the first solder and the second solder, wherein the melting point of the second solder is higher than the melting point of the first solder.

[0036] Optionally, the area of ​​the alloy does not exceed the prepared overlap area.

[0037] Optionally, the melting point of the alloy formed by the first solder and the second solder at the overlapping portion is higher than the temperature of the lamination process of the battery cell.

[0038] Optionally, the first solder is any one of the following:

[0039] The first solder is a ternary alloy of tin, lead, and bismuth, and the mass percentage of bismuth in the first solder is greater than or equal to 1% and less than or equal to 30%;

[0040] The first solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the first solder is greater than 0% and less than or equal to 5%.

[0041] Optionally, the second solder is any one of the following:

[0042] The second solder is a ternary alloy of tin, lead, and bismuth, and the mass percentage of bismuth in the second solder is at least less than 30%;

[0043] The second solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the second solder is at least less than 5%;

[0044] The second solder is a ternary alloy of tin, lead and silver, and the mass percentage of silver in the second solder is greater than 0% and less than or equal to 5%;

[0045] The second solder is a tin-lead binary alloy, and the mass percentage of lead in the second solder is greater than 20% and less than or equal to 50%.

[0046] Optionally, the length of the overlapping portion is not shorter than 1 mm, and the length of the alloy is not shorter than 1 mm.

[0047] Optionally, the end of the alloy away from the first cell does not exceed the end of the connection line associated with the outermost subgrid on the first cell away from the first cell in a direction perpendicular to the long side inward of the first cell.

[0048] In a fourth aspect, a photovoltaic assembly is provided, comprising a battery string as described in any one of the third aspects above.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] One aspect of the present application provides a battery string repair method, comprising using the remaining solder ribbon connected to adjacent battery cells after being cut as the solder ribbon to be welded, placing a replacement battery cell, welding the overlap between the solder ribbon to be welded and a second solder ribbon on the replacement battery cell, and using the alloy formed by welding at the overlap to fix the replacement battery cell to the adjacent battery cell. Because the melting point of the second solder of the second solder ribbon is higher than the melting point of the first solder of the solder to be welded, the melting point of the alloy is also higher than the melting point of the first solder. Thus, the present application uses the alloy to fix the replacement battery cell to the adjacent battery cell, which can make the connection between the battery cells more reliable, thereby reducing the probability of failure during battery string repair.

[0051] One aspect of the present application provides a method for preparing a replacement cell, comprising providing a cell substrate and placing a replacement solder strip on the cell substrate. Because the melting point of the replacement solder covering the surface of the replacement solder strip is higher than the melting point of the solder covering the surface of the solder strip on the failed cell it is replacing, when the replacement cell is used for repair, the melting point of the alloy formed will also be higher than the melting point of the solder covering the surface of the solder strip on the failed cell. Thus, using the replacement cell can reduce the probability of failure of the cell string during repair. Furthermore, the preparation method of the replacement cell is simple and has good practicality.

[0052] One aspect of the present application also provides a battery string, including a first battery cell and a second battery cell, wherein the surface of the first welding strip of the first battery cell is covered with a first solder, and the surface of the second welding strip of the second battery cell is covered with a second solder. The battery string is connected by overlapping the first welding strip and the second welding strip, and the overlapping part has an alloy of the first solder and the second solder. Since the melting point of the second solder is higher than the melting point of the first solder, the melting point of the alloy of the first solder and the second solder is also higher than the melting point of the first solder. In this way, the connection between the first battery cell and the second battery cell in the battery string is reliable, reducing the probability of failure of the battery string due to rework.

[0053] One aspect of the present application also provides a photovoltaic module, including the cell string mentioned above. Since the melting point of the second solder in the cell string contained in the photovoltaic module is higher than the melting point of the first solder, the melting point of the alloy of the first solder and the second solder is also higher than the melting point of the first solder. This makes the connection between the cell elements in the cell string reliable, and can reduce the probability of failure of the photovoltaic module due to repair.

[0054] Summary of the Figures

[0055] The accompanying drawings are included to provide a further understanding of the present application. They are incorporated into and constitute a part of the present application. The accompanying drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0056] In the attached figure:

[0057] Figures 1 and 2 are schematic diagrams of a related battery string repair technology for comparison;

[0058] FIG3 is a flow chart of a battery string repair method provided in one embodiment of the present application;

[0059] FIG4 is a schematic diagram of a battery string to be repaired according to an embodiment of the present application;

[0060] FIG5 is a schematic diagram of a truncation of a welding ribbon provided in one embodiment of the present application;

[0061] FIG6 is a schematic diagram of placing a replacement battery cell according to an embodiment of the present application;

[0062] FIG7 is a schematic diagram of a welding ribbon provided in one embodiment of the present application;

[0063] FIG8 is a schematic diagram of the length of an alloy formed after overlapping according to an embodiment of the present application;

[0064] FIG9 is a schematic diagram of a battery string repaired according to some known repair methods;

[0065] FIG10 is a schematic diagram of a battery string that can be obtained in this embodiment;

[0066] FIG11 is a flow chart of a method for preparing a replacement battery cell according to an embodiment of the present application;

[0067] FIG12 and FIG13 are schematic diagrams of a repaired battery string provided in one embodiment of the present application;

[0068] FIG14 is a schematic diagram of a photovoltaic module provided in one embodiment of the present application.

[0069] Preferred embodiment of this application

[0070] To more clearly illustrate the technical solutions of the embodiments of this application, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0071] As used in this application and the claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0072] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0073] In the description of this application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of this application; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0074] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0075] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. Furthermore, while the terms used in this application are selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, this application should be understood not only by the actual terms used, but also by the meaning implied by each term.

[0076] Currently, as shown in FIG1 , when a battery cell in a battery string needs to be replaced due to a fault, the solder strip connecting the faulty battery cell and its adjacent battery cell can be cut off, and then the faulty battery cell can be replaced with a qualified battery cell. The qualified battery cell and the adjacent battery cell can then be welded together by heating and melting the solder of the solder strip on the qualified battery cell and the solder of the solder strip on the adjacent battery cell.

[0077] However, as shown in Figure 2, under high external temperatures (for example, during the lamination process following the soldering step, where the lamination temperature outside the battery string is greater than 140°C), the solder between the qualified battery cells secured in this manner and the adjacent battery cells may remelt. This can cause the battery cells to separate again, leading to the failure of the battery string after repair.

[0078] To address the above technical issues, one aspect of the present application provides a battery string repair method, which includes using the remaining solder ribbon connected to adjacent battery cells after being cut as the solder ribbon to be welded, placing a replacement battery cell, welding the overlapping portion of the solder ribbon to be welded and the second solder ribbon on the replacement battery cell, and using the alloy formed by welding at the overlapping portion to fix the replacement battery cell to the adjacent battery cell. Because the melting point of the second solder of the second solder ribbon is higher than the melting point of the first solder of the solder to be welded, the melting point of the alloy is also higher than the melting point of the first solder. This method can make the connection between the battery cells more reliable, thereby reducing the probability of failure during battery string repair.

[0079] The following flowcharts will be used to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the various steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more operations can be removed from these processes.

[0080] Referring to FIG. 3 , one embodiment of the present application provides a battery string repair method, comprising:

[0081] S301, cutting off the first welding ribbon between the faulty battery cell and its adjacent battery cell in the battery string to be repaired, and using the remaining welding ribbon connected to the adjacent battery cell after cutting off as the welding ribbon to be welded.

[0082] The first soldering tape may include a first conductive substrate and a first solder. The first solder may be wrapped around the surface of the first conductive substrate.

[0083] In one embodiment, the first conductive substrate is copper; the first solder can be any one of the materials shown in Table 1:

[0084] Table 1

[0085] It is understood that there may be one or more adjacent solar cells, and the first solder strips connecting each adjacent solar cell to the faulty solar cell may include the same or different first conductive substrates and first solders. For ease of understanding, in this embodiment, the two adjacent solar cells connected to the faulty solar cell are referred to as the first adjacent solar cell and the second adjacent solar cell, respectively, wherein the first adjacent solar cell and the second adjacent solar cell use the same first conductive substrate and first solder.

[0086] Exemplarily, as shown in FIG4 , a schematic diagram of a battery string to be repaired provided in this embodiment is provided. There is a faulty battery cell that needs to be replaced in the repaired battery string, and the faulty battery cell is connected to its adjacent battery cell by a first welding ribbon. Specifically in FIG4 , the first adjacent battery cell is connected to the left side of the faulty battery cell, and the second adjacent battery cell is connected to the right side of the faulty battery cell. As shown in FIG4 , a first welding ribbon a is connected between the first adjacent battery cell and the faulty battery cell (only one is pointed to in the figure, and it should be understood that all other welding ribbons connected between the first adjacent battery cell and the faulty battery cell can be used as the first welding ribbon a); a first welding ribbon b is connected between the second adjacent battery cell and the faulty battery cell (only one is pointed to in the figure, and it should be understood that all other welding ribbons connected between the second adjacent battery cell and the faulty battery cell can be used as the first welding ribbon b).

[0087] In this embodiment, the first conductive substrates of the first welding strip a and the first welding strip b are both copper; the first solders of the first welding strip a and the first welding strip b are both tin-lead-bismuth ternary alloys, which include the following components in mass percentage: 37% tin, 37% lead, and 26% bismuth.

[0088] In one embodiment, a first truncation position is determined on the first welding strip between the faulty battery cell and the first adjacent battery cell, and a second truncation position is determined on the first welding strip between the faulty battery cell and the second adjacent battery cell, and then the first welding strip between the faulty battery cell and the first adjacent battery cell and the second adjacent battery cell are cut along the first truncation position and the second truncation position, respectively.

[0089] The distance between the first truncation point and the long side of the faulty battery cell is a first length, the distance between the second truncation point and the long side of the faulty battery cell is a second length, and the second length does not exceed the first length.

[0090] For example, as shown in Figure 5, a first cutoff point is defined on the first soldering ribbon between the faulty cell and the first adjacent cell. The distance between the first cutoff point and the long side of the faulty cell is a first length, L1. A second cutoff point is defined on the first soldering ribbon between the faulty cell and the second adjacent cell. The distance between the second cutoff point and the long side of the faulty cell is a second length, L2. As shown in Figure 5, L2 does not exceed L1.

[0091] For ease of representation, after truncation, in this embodiment, the remaining soldering ribbon connected to the first adjacent cell is referred to as a soldering ribbon c to be soldered, and the remaining soldering ribbon connected to the second adjacent cell is referred to as a soldering ribbon d to be soldered.

[0092] S302: Remove the faulty battery cell and place a replacement battery cell at the corresponding removal position.

[0093] The replacement cell is provided with a second solder strip, which may include a second conductive substrate and a second solder. The second solder may cover a surface of the second conductive substrate. The second solder has a higher melting point than the first solder.

[0094] In one embodiment, the second conductive substrate is copper, and the second solder can be any one of the materials shown in Table 2 below:

[0095] Table 2

[0096] It is understood that, in practical applications, those skilled in the art may use any of the materials shown in Table 1 above as the first solder, and may also use any of the materials shown in Table 2 above as the second solder. For example, a ternary tin-lead-bismuth alloy (comprising the following components in mass percentage: 37% tin, 37% lead, 26% bismuth) may be used as the first solder, and a binary tin-lead alloy (comprising the following components in mass percentage: 70% tin, 30% lead) may be used as the second solder.

[0097] Preferably, when the first solder and the second solder used by those skilled in the art are both ternary alloys of tin-lead-bismuth, the mass percentage of bismuth in the second solder is also less than the mass percentage of bismuth in the first solder.

[0098] For example, a first tin-lead-bismuth ternary alloy (comprising the following components in mass percentage: 37% tin, 37% lead, 26% bismuth) can be used as the first solder, and a second tin-lead-bismuth alloy (comprising the following components in mass percentage: 43% tin, 43% lead, 14% bismuth) can be used as the second solder.

[0099] Preferably, when the first solder and the second solder used by those skilled in the art are both tin-lead-indium ternary alloys, the mass percentage of indium in the second solder is also smaller than the mass percentage of indium in the first solder.

[0100] In the present embodiment, for ease of understanding, a first tin-lead-bismuth ternary alloy (comprising the following mass percentages: 37% tin, 37% lead, and 26% bismuth) is used as the first solder, and a second tin-lead-bismuth alloy (comprising the following mass percentages: 43% tin, 43% lead, and 14% bismuth) is used as the second solder. The melting point of the first solder is 140 degrees Celsius. The melting point of the second solder is 160 degrees Celsius.

[0101] Figure 6 shows a schematic diagram of placing a replacement cell according to this embodiment. The replacement cell is placed in the same position as the failed cell. A second soldering ribbon e is provided on the side of the replacement cell closest to the first adjacent cell, and a second soldering ribbon f is provided on the side of the replacement cell closest to the second adjacent cell.

[0102] In this embodiment, the second conductive base materials of the second welding strips e and f are both copper; the second solders of the second welding strips e and f are both tin-lead-bismuth ternary alloys, which include the following components in mass percentage: 43% tin, 43% lead, and 14% bismuth.

[0103] S303: Overlap the welding strip to be welded and the second welding strip, and weld the overlapping portion between the welding strip to be welded and the second welding strip.

[0104] In the welding process, the first solder on the surface of the welding strip to be welded and the second solder on the surface of the second welding strip are melted at the overlapping part and form an alloy on the area covering the overlapping part. The alloy formed by welding at the overlapping part fixes the replacement battery cell and the adjacent battery cell.

[0105] In one embodiment, the melting point of the alloy formed by the first solder and the second solder is higher than the temperature of the cell lamination process.

[0106] In one embodiment, the overlapping portion between the welding ribbon to be welded and the second welding ribbon can be welded by any one or a combination of the following methods: soldering iron heating, infrared heating, hot air heating, electromagnetic heating, and laser welding.

[0107] For example, as shown in FIG7 , the welding ribbon c to be welded is overlapped with the second welding ribbon e, and the welding ribbon d to be welded is overlapped with the second welding ribbon f, so as to weld the overlapping portion C between the welding ribbon c and the second welding ribbon e, and the overlapping portion D between the welding ribbon d and the second welding ribbon f. During the welding process between the welding ribbon d and the second welding ribbon f, the first solder on the surface of the welding ribbon d and the second solder on the surface of the second welding ribbon f melt at the overlapping portion D, thereby forming an alloy in the area covering the overlapping portion D, thereby securing the first adjacent cell to the replacement cell. Similarly, during the welding process between the welding ribbon c and the second welding ribbon e, the first solder on the surface of the welding ribbon c and the second solder on the surface of the second welding ribbon e melt at the overlapping portion C, thereby forming an alloy in the area covering the overlapping portion C, thereby securing the second adjacent cell to the replacement cell.

[0108] When the melting point of the alloy formed on the overlapping parts C and D is higher than the temperature of the battery cell lamination process, the alloy will not melt even if the repaired battery string is put back into the subsequent lamination process. Therefore, the repaired battery string will not be separated again during the lamination process, avoiding the failure of the battery string during repair.

[0109] The present embodiment will be compared with some known rework methods from the perspective of process difficulty.

[0110] One known rework method is colloid fixing, which involves applying colloid to the overlapping joint of two solder ribbons at the rework site and then curing the colloid to secure the overlapping ribbons. One disadvantage of this rework method is that if the colloid is only applied between the two ribbons, it can easily soften, causing the ribbons to separate. Another disadvantage is that if the colloid fully covers the ribbons, it may affect subsequent steps in the battery string. For example, when handling battery cells during the lamination process, if the colloid is applied high enough, there is a risk of puncturing the encapsulation film.

[0111] Another possible rework method is to use high-temperature solder to assist in fixing, that is, to apply auxiliary high-temperature solder to the overlapping position of the rework area, and to fix the solder strips at the overlapping position by wrapping the two solder strips with high-temperature solder. This method is used as a solution because it can prevent the solder from remelting. However, the inventors of this application found that this rework method still has some disadvantages. First, when high-temperature solder is applied to the overlapping position of the rework area, solder accumulation and solder burrs are likely to occur, which may affect the subsequent processes of the battery string. For example, when processing battery cells in the lamination process, if the height of the accumulated solder or burrs reaches a certain level, there may be a risk of piercing the packaging film. Secondly, the accumulated solder or burrs may also cause the insulation performance of the component to deteriorate, and it is more likely to cause stress concentration in the battery string, causing it to break.

[0112] Compared with the colloid fixing method, the battery string repair method in this embodiment uses an alloy to fix the replacement battery cell and the adjacent battery cell. The alloy will not soften, so it can avoid the separation of the solder ribbon caused by the softening of the colloid in method one; and the alloy does not need to completely wrap the two solder ribbons, so it can also avoid the risk of piercing the packaging film due to the height of the colloid applied.

[0113] Compared to high-temperature solder-assisted methods, the battery string repair method of this embodiment uses an alloy to secure the replacement cell to the adjacent cell. This alloy prevents solder buildup and burrs, thus preventing accumulated solder or burrs from piercing the encapsulation film. This also prevents deterioration of the module's insulation performance and damage to the battery string. In one embodiment, the overlapped joint is no less than 1 mm long, and the resulting alloy is no less than 1 mm long.

[0114] As shown in FIG7 , between the overlapping welding strip d and the second welding strip f, the length of the overlapping portion D is 1.5 mm, and the length of the formed alloy is 1.5 mm, which can ensure that the connection between the replacement battery cell and the second adjacent battery cell is more reliable.

[0115] In one embodiment, the end of the alloy away from the adjacent cell does not exceed the end of the connecting line associated with the outermost secondary grid on the adjacent cell in the direction perpendicular to the long side inward.

[0116] As shown in FIG8 , the end of the alloy away from the second adjacent cell (represented by an elliptical shape in FIG5 , marked as E1) does not exceed the end of the connecting line associated with the outermost sub-grid on the second adjacent cell away from the second adjacent cell (marked as E2) along the direction perpendicular to the long side box of the second adjacent cell.

[0117] Furthermore, the present embodiment will be compared with some of the above-mentioned known rework methods from the perspective of process cost.

[0118] The inventors discovered that, in the actual process of repairing a battery string using a colloid fixing method or a high-temperature solder auxiliary fixing method, the area of ​​the applied colloid (or high-temperature auxiliary material) is often larger than the prepared overlap area, and the portion of the colloid (or high-temperature auxiliary material) that exceeds the overlap is likely to contact the main grid connection lines of the battery cell, thereby increasing the risk of failure of the battery cell during the production process. For example, as shown in Figure 9, a schematic diagram of a battery string repaired according to a known repair method is shown. The two solder strips at the overlap of this battery string are fixed by applying colloid (or high-temperature auxiliary material), and the area of ​​the applied colloid (or high-temperature auxiliary material) is larger than the prepared overlap area. In order to avoid short-circuit failure of the battery cell when the portion of the colloid (or high-temperature auxiliary material) that exceeds the overlap contacts the main grid connection lines of the battery cell, a solution that may be adopted by the above-mentioned known methods is to increase the length of the main grid connection line of the battery cell. As shown in Figure 9, the length of the main grid connection line of the battery cell is increased to 5 auxiliary grid intervals. It can be seen that even though this solution can to a certain extent prevent the risk of failure of the above-mentioned cell repaired in the known manner, it increases the length of the main grid connection line of the cell, which will significantly increase the process cost required for repairing the cell string.

[0119] Further comparison revealed that the two welding strips at the overlap in this embodiment are fixed together by an alloy formed by the first solder and the second solder, and the area of ​​the alloy will not exceed the prepared overlap area, thus avoiding the risk of failure of the battery cell due to contact between the alloy and the main grid connection line of the battery cell. In addition, this embodiment achieves full utilization of the overlap area, so there is no need to increase the length of the main grid connection line of the battery cell, which significantly reduces the process cost required for repairing the battery string compared to the above-mentioned known methods. For example, as shown in Figure 10, a schematic diagram of a battery string that can be obtained in this embodiment is shown. The two welding strips at the overlap of this battery string are fixed together by the alloy formed. Since the area of ​​the alloy will not exceed the prepared overlap area, the length of the main grid connection line of the battery cell does not need to be increased. As shown in Figure 10, the length of the main grid connection line of the battery cell is 3 sub-grid intervals. It can be seen that compared with the battery string shown in Figure 9, the process cost required for repairing a battery string that can be obtained in this embodiment can be significantly reduced.

[0120] Furthermore, referring to FIG11 , the present application provides a method for preparing a replacement battery cell, comprising:

[0121] S1101, set up a battery substrate.

[0122] S1102, set a replacement solder strip on the battery substrate.

[0123] The surface of the replacement solder strip is covered with a replacement solder, and the melting point of the replacement solder is higher than the melting point of the solder covering the surface of the solder strip on the faulty battery cell to be replaced by the replacement battery cell.

[0124] Because the melting point of the replacement solder covering the surface of the replacement ribbon is higher than the melting point of the solder covering the surface of the ribbon on the failed cell it is replacing, when the replacement cell is used for repair, the melting point of the alloy formed will also be higher than the melting point of the solder covering the surface of the ribbon on the failed cell. This can reduce the probability of failure of the battery string during repair. The preparation method of the replacement cell is simple and has good practicality.

[0125] Some details of replacing the battery cell can be referred to the above-mentioned battery cell repair method embodiment, which will not be repeated here.

[0126] The present application also provides a battery string, as shown in Figures 12 and 13, which includes:

[0127] The first battery cell 121 has a first solder strip 1211 , and the surface of the first solder strip 1211 is covered with a first solder 12111 ;

[0128] The second battery cell 122 has a second solder strip 1221 , and the surface of the second solder strip is covered with a second solder 12211 ;

[0129] The first battery cell 121 and the second battery cell 122 are connected by overlapping the first welding ribbon 1211 and the second welding ribbon 1221 , and the overlapping portion has an alloy 123 of the first solder 12111 and the second solder 12211 , and the melting point of the second solder 12211 is higher than the melting point of the first solder 12111 .

[0130] In one embodiment, the melting point of the alloy 113 formed by the first solder 12111 and the second solder 12211 at the overlapping portion is higher than the temperature of the cell lamination process.

[0131] In one embodiment, the first solder 12111 is any one of the following:

[0132] The first solder 12111 is a ternary alloy of tin, lead, and bismuth, and the mass percentage of bismuth in the first solder 12111 is greater than or equal to 1% and less than or equal to 30%;

[0133] The first solder 12111 is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the first solder 12111 is greater than 0% and less than or equal to 5%.

[0134] In one embodiment, the second solder 12211 is any one of the following:

[0135] The second solder 12211 is a ternary alloy of tin, lead, and bismuth, and the mass percentage of bismuth in the second solder 12211 is at least less than 30%;

[0136] The second solder 12211 is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the second solder 12211 is at least less than 5%;

[0137] The second solder 12211 is a ternary alloy of tin, lead, and silver, and the mass percentage of silver in the second solder 12211 is greater than 0% and less than or equal to 5%;

[0138] The second solder 12211 is a tin-lead binary alloy, and the mass percentage of lead in the second solder 12211 is greater than 20% and less than or equal to 50%.

[0139] In one embodiment, the length of the overlapped portion is not shorter than 1 mm, and the length of the alloy 113 is not shorter than 1 mm.

[0140] In one embodiment, the end of the alloy 113 away from the first cell does not exceed the end of the connecting line associated with the outermost sub-grid on the first cell 121 away from the first cell 121 in the direction perpendicular to the long side inward of the first cell 121.

[0141] Since the melting point of the second solder 12211 in the battery string is higher than the melting point of the first solder 12111, the melting point of the alloy 113 of the first solder 12111 and the second solder 12211 is also higher than the melting point of the first solder 12111. In this way, the connection between the first battery cell 121 and the second battery cell 122 in the battery string is reliable, reducing the probability of failure of the battery string during repair.

[0142] Some details of the battery string embodiment can be referred to the embodiment of the battery string repair method described above, which will not be repeated here.

[0143] Furthermore, referring to FIG. 14 , the present application also provides a photovoltaic assembly, including a cell string 14 . The cell 14 may be a cell string as shown in FIG. 12 or 13 .

[0144] Since the melting point of the second solder in the cell string 14 included in the photovoltaic module is higher than the melting point of the first solder, the melting point of the alloy of the first solder and the second solder is also higher than the melting point of the first solder. This makes the connection of the cell elements in the cell string 14 more reliable, thereby reducing the probability of failure of the photovoltaic module due to repair.

[0145] Some details of the photovoltaic module embodiment can be referred to the embodiment of the battery string repair method described above, which will not be repeated here.

[0146] The basic concepts have been described above. It will be apparent to those skilled in the art that the above disclosures are merely illustrative and do not constitute limitations on this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to this application. Such modifications, improvements, and amendments are suggested in this application and remain within the spirit and scope of the exemplary embodiments of this application.

[0147] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0148] Similarly, it should be noted that, in order to simplify the presentation of this application and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this application sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of this application requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single embodiment disclosed above.

[0149] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0150] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A battery string repair method, characterized in that: include: Cutting off the first welding strip between the faulty battery cell and its adjacent battery cell in the battery string to be repaired, and using the remaining welding strip connected to the adjacent battery cell after cutting off as the welding strip to be welded, wherein the surface of the first welding strip is covered with a first solder containing tin; Remove the faulty battery cell and place a replacement battery cell at the corresponding removal position, wherein the replacement battery cell is provided with a second solder strip, the surface of the second solder strip is covered with a second solder containing tin, and the melting point of the second solder is higher than the melting point of the first solder; The welding strip to be welded is overlapped with the second welding strip, and the overlapping parts of the welding strip to be welded and the second welding strip are welded, and the alloy formed by welding the overlapping parts fixes the replacement battery cell and the adjacent battery cell.

2. The method according to claim 1, characterized in that The area of ​​the alloy will not exceed the prepared overlap area.

3. The method according to claim 1 or 2, characterized in that The melting point of the alloy formed by the first solder and the second solder at the overlapping portion is higher than the temperature of the lamination process of the battery cell.

4. The method according to claim 1 or 2, characterized in that: The method of cutting off the first welding strip between the faulty battery cell and the adjacent battery cell in the battery string to be repaired comprises: A first truncation position is determined on the first welding strip between the faulty battery cell and the first adjacent battery cell, and a second truncation position is determined on the first welding strip between the faulty battery cell and the second adjacent battery cell, wherein the distance between the first truncation position and the long side of the faulty battery cell is a first length, the distance between the second truncation position and the long side of the faulty battery cell is a second length, and the second length does not exceed the first length; The first welding strips between the faulty battery cell and the first adjacent battery cell and the second adjacent battery cell are respectively cut off along the first cutting position and the second cutting position.

5. The method according to claim 1 or 2, characterized in that: The first solder is any one of the following: The first solder is a ternary alloy of tin, lead and bismuth, and the mass percentage of bismuth in the first solder is greater than or equal to 1% and less than or equal to 30%; The first solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the first solder is greater than 0% and less than or equal to 5%.

6. The method according to claim 5, characterized in that The second solder is any one of the following: The second solder is a ternary alloy of tin, lead and bismuth, and the mass percentage of bismuth in the second solder is less than 30%; The second solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the second solder is less than 5%; The second solder is a ternary alloy of tin, lead and silver, and the mass percentage of silver in the second solder is greater than 0% and less than or equal to 5%; The second solder is a tin-lead binary alloy, and the mass percentage of lead in the second solder is greater than 20% and less than or equal to 50%.

7. The method according to any one of claims 1 to 6, characterized in that: The welding of the overlapped portion between the welding strip to be welded and the second welding strip comprises any one or a combination of the following methods: Soldering iron heating method, infrared heating method, hot air heating method, electromagnetic heating method, laser welding method.

8. The method according to any one of claims 1 to 6, characterized in that: The length of the overlapping portion is not shorter than 1 mm, and the length of the alloy is not shorter than 1 mm.

9. The method according to any one of claims 1 to 6, characterized in that: The end of the alloy away from the adjacent cell does not exceed the end of the connecting line associated with the outermost subgrid on the adjacent cell away from the adjacent cell in the direction perpendicular to the long side inward of the adjacent cell.

10. A method for preparing a replacement battery cell, characterized in that: include: Provide a battery substrate; A replacement solder strip is arranged on the battery substrate, wherein the surface of the replacement solder strip is covered with a replacement solder containing tin, and the melting point of the replacement solder is higher than the melting point of the solder covering the surface of the solder strip on the faulty battery cell to be replaced by the replacement battery cell.

11. The preparation method according to claim 10, characterized in that: The replacement solder and the solder form an alloy, and the area of ​​the alloy does not exceed the prepared overlapping area.

12. A battery string, characterized in that: include: A first battery cell has a first solder strip, wherein a surface of the first solder strip is covered with a first solder containing tin; A second battery cell has a second solder strip, wherein a surface of the second solder strip is covered with a second solder containing tin; The first battery cell and the second battery cell are connected by overlapping the first solder strip and the second solder strip, and the overlapping portion has an alloy of the first solder and the second solder, wherein the melting point of the second solder is higher than the melting point of the first solder.

13. The battery string according to claim 12, characterized in that: The area of ​​the alloy will not exceed the prepared overlap area.

14. The battery string according to claim 12 or 13, characterized in that: The melting point of the alloy formed by the first solder and the second solder at the overlapping portion is higher than the temperature of the lamination process of the battery cell.

15. The battery string according to claim 12 or 13, characterized in that: The first solder is any one of the following: The first solder is a ternary alloy of tin, lead and bismuth, and the mass percentage of bismuth in the first solder is greater than or equal to 1% and less than or equal to 30%; The first solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the first solder is greater than 0% and less than or equal to 5%.

16. The battery string according to claim 15, characterized in that: The second solder is any one of the following: The second solder is a ternary alloy of tin, lead and bismuth, and the mass percentage of bismuth in the second solder is less than 30%; The second solder is a ternary alloy of tin, lead and indium, and the mass percentage of indium in the second solder is less than 5%; The second solder is a ternary alloy of tin, lead and silver, and the mass percentage of silver in the second solder is greater than 0% and less than or equal to 5%; The second solder is a tin-lead binary alloy, and the mass percentage of lead in the second solder is greater than 20% and less than or equal to 50%.

17. The battery string according to any one of claims 12 to 16, characterized in that: The length of the overlapping portion is not shorter than 1 mm, and the length of the alloy is not shorter than 1 mm.

18. The battery string according to any one of claims 12 to 16, characterized in that: The end of the alloy away from the first battery cell does not exceed the end of the connection line associated with the outermost sub-grid on the first battery cell away from the first battery cell in the direction perpendicular to the long side and inward.

19. A photovoltaic module, characterized in that: The photovoltaic module comprises the battery string according to any one of claims 12 to 18.

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