Battery string and method of manufacturing a battery string

Abstract

The application provides a battery string and a preparation method of the battery string. The battery string (10) comprises a first battery piece (11), a second battery piece (12), a first solder wire (3), a second solder wire (6) and a protective film (2). The second battery piece and the first battery piece are arranged adjacent to each other and form an adjacent area between each other. The first solder wire comprises a first part connected with a grid line with a first polarity of the first battery piece and a second part connected with a grid line with a second polarity of the second battery piece. The first part and the second part are spaced apart from each other at the adjacent area. The second solder wire comprises a third part connected with a grid line with the second polarity of the first battery piece and a fourth part connected with a grid line with the first polarity of the second battery piece. The third part and the fourth part are connected with each other at the adjacent area. The protective film is located between the first solder wire and the adjacent area. When the first solder wire is disconnected at the adjacent area, the protective film can protect the battery piece and avoid the battery piece from being damaged by laser.

Description

Technical Field

[0001] This disclosure belongs to the field of solar cell module technology, specifically relating to a cell string and a method for preparing the cell string. Background Technology

[0002] In the photovoltaic industry, multi-wire technology has been widely adopted due to its advantages such as low resistance, high power, and low silver loss. In multi-wire, high-density cell module technology, especially in advanced packaging processes that achieve negative spacing between cells, the fabrication of multi-wire cell strings typically employs an inter-cell breaking method. To achieve true negative spacing, the bonding wires must be precisely broken at specific locations on the cell.

[0003] However, when laser breaking technology is applied to automated production lines, the following technical challenges exist: the solar cells are at risk of damage. The anti-reflective coating and PN junction on the surface of solar cells are extremely sensitive to thermal and mechanical stress. If the laser energy is not properly controlled, it can easily lead to microcracks, burn-through holes, or thermal damage to the anti-reflective coating. Summary of the Invention

[0004] This disclosure aims to solve the aforementioned technical problems. This disclosure provides a battery string and a method for manufacturing the battery string, thereby providing an integrated solution to solve the aforementioned technical problems.

[0005] To achieve the above objectives, according to one aspect, a battery string is provided. The battery string includes: a first battery cell; a second battery cell, the second battery cell and the first battery cell being disposed adjacent to each other and forming adjacent regions between them; a first welding wire, the first welding wire including a first portion connected to a grid line of the first battery cell having a first polarity and a second portion connected to a grid line of the second battery cell having a second polarity, the first portion and the second portion being spaced apart from each other in the adjacent regions; a second welding wire, the second welding wire including a third portion connected to a grid line of the first battery cell having a second polarity and a fourth portion connected to a grid line of the second battery cell having a first polarity, the third portion and the fourth portion being connected to each other in the adjacent regions; and a protective film, the protective film being located between the first welding wire and the adjacent regions.

[0006] Based on the above aspects, by setting a protective film between the first welding wire and the adjacent area, the protective film can protect the solar cell when the first welding wire breaks in the adjacent area, preventing the solar cell from being damaged by laser. Accordingly, it is possible to manufacture solar cell strings or photovoltaic modules with a high product yield.

[0007] Preferably, the protective film includes: a substrate layer; and an attachment portion disposed on a surface of the substrate layer facing the adjacent region in the thickness direction and bonded to the adjacent region, wherein a recess is provided on the opposite side of the substrate layer in the thickness direction.

[0008] According to the above structure, a recess is provided on the surface of the substrate layer on the other side. This recess reduces the contact area and adhesion between the substrate layer and the waste filament. Therefore, after laser filament breakage, the protective film further reduces the contact area and adhesion between the waste filament and the protective film, facilitating the removal of waste filament and spatter generated during the breakage process. This reduces the risk of short circuits in the solar cells caused by waste filament, thus protecting the solar cells.

[0009] Preferably, the recess includes multiple pits and / or multiple grooves. These pits and / or grooves reduce the contact area and adhesion between the waste wire and the protective film, effectively preventing the welding wire from adhering to the protective film surface due to static electricity or molten adhesion. This provides protection for the battery cell.

[0010] Preferably, each of the recesses has a cross-section perpendicular to the thickness direction that is circular, square, or trapezoidal, and the plurality of recesses are arranged in a matrix; and / or the opening size of the recesses is 10-30 μm. Typically, the length of the waste wire is about 0.1 mm. Thus, the recess provides a simple microstructure and ensures that the waste wire does not easily enter the recess after laser breaking.

[0011] Preferably, the groove is a V-shaped groove and / or a U-shaped groove. This provides a simple microstructure.

[0012] Preferably, each of the trenches is elongated, and the trenches are parallel to each other and spaced apart along a width direction perpendicular to their length, and / or, the opening width of each trench is 10-30 μm. This structure ensures that waste filaments do not easily enter the trenches after laser ablation. This provides protection for the solar cell.

[0013] Preferably, the substrate layer is made of one of the following materials: polyimide (PI), polyethylene cyclohexyl dicarboxylate, nylon, polyphenylene sulfide, and polyethylene naphthalate. These materials have excellent high-temperature resistance and can withstand the instantaneous thermal shock generated during laser processing, ensuring the integrity of the film strip's structure and the absence of functional degradation during the process, thereby preventing the adhesion of the film strip and waste filaments.

[0014] Preferably, the protective film includes laser-reflective particles; specifically, the laser-reflective particles are uniformly mixed in the substrate layer. Thus, the protective film has high reflectivity to efficiently reflect most of the incident laser energy, thereby significantly attenuating the energy transmitted to the solar cell.

[0015] Preferably, the laser reflective particles are titanium dioxide or barium sulfate. This ensures that the vast majority of the incident laser energy is efficiently reflected, thereby significantly attenuating the energy transmitted to the solar cell and fundamentally preventing microcracks, perforations, or damage to the antireflective coating caused by thermal effects.

[0016] Preferably, the attachment portion comprises a plurality of discrete attachment portions or a continuous attachment layer; and / or the material of the attachment portion comprises hot melt adhesive or pressure-sensitive adhesive. The attachment portion fixes the protective film to the surface of the battery cell. Thus, the attachment portion can be easily implemented with a simple structure and the protective film can be easily fixed to the battery cell.

[0017] Preferably, the hot melt adhesive is EVA or POE. This allows for the provision of attachments at a lower cost.

[0018] Preferably, the first and second solar cells are partially stacked on top of each other in the adjacent regions. Accordingly, high-density battery strings can be manufactured with high product yield.

[0019] According to another aspect, this disclosure provides a method for preparing a battery string, comprising the following steps: providing a first battery cell and a second battery cell, the first battery cell and the second battery cell being placed adjacent to each other and forming an adjacent region between them; disposing a protective film on the adjacent region of the first battery cell and the second battery cell; laying a first welding wire and a second welding wire, and using a laser to cut the first welding wire located in the adjacent region to form a first portion and a second portion; and applying an airflow to sweep the adjacent region, such that waste wire generated by the laser cutting of the first welding wire in the adjacent region falls off from the surface of the protective film.

[0020] In the above preparation method, during laser breaking, the laser energy passing through the first welding wire and the area next to it reaches the protective film and is blocked by the protective film, thereby protecting the battery cell and preventing microcracks, perforations, or damage to the anti-reflective film caused by thermal effects. Consequently, battery strings can be manufactured with a high product yield.

[0021] In one embodiment, the method is performed on a feeding cylinder, wherein the solar cells are arranged with a negative spacing on the feeding cylinder. Alternatively, in another embodiment, the method can be performed on multiple feeding platforms in a cyclic conveying manner, wherein the width of one feeding platform corresponds to the size of one solar cell, and the solar cells are arranged with a negative spacing on the multiple feeding platforms.

[0022] Compared with the prior art, this disclosure has the following beneficial effects: by setting a protective film between the first welding wire and the adjacent area, this solution can protect the battery cell when the first welding wire is disconnected in the adjacent area, and prevent the battery cell from being damaged by laser.

[0023] It should be understood that this disclosure is not intended to achieve all of the above-described technical effects, but rather to achieve one or more of the aforementioned technical effects. Technical solutions that achieve only one technical effect are also included within the scope of protection claimed in this disclosure. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating a battery string manufacturing device in the prior art; Figure 2 This is a plan view showing a protective film according to a first embodiment of the present disclosure; Figure 3 It shows Figure 2 The cross-sectional view shown is taken along line III-III of the protective film according to this disclosure; Figure 4 This is a plan view showing the protective film according to the second embodiment of the present disclosure; Figure 5 It shows Figure 4 The cross-sectional view shown is a section taken along line VV of the protective film according to this disclosure; Figure 6 This is a plan view showing the protective film according to the third embodiment of the present disclosure; Figure 7 It shows Figure 6 The cross-sectional view shown is taken along line VII-VII of the protective film according to this disclosure; Figure 8 This is a plan view showing the protective film according to the fourth embodiment of the present disclosure; Figure 9 It shows Figure 8 The cross-sectional view shown is taken along line IX-IX of the protective film according to this disclosure; Figure 10 This shows a plan view of a battery string according to the present disclosure; Figure 11 yes Figure 10 A magnified view of part A of the battery string; Figure 12 This is a flowchart illustrating a method for preparing a battery string according to the present disclosure.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1. Battery cell; 10. Battery string; 11. First battery cell; 12. Second battery cell; 2. Protective film; 20. Substrate layer; 21. Attachment; 22. Dent; 23. Dent; 24. Groove; 25. Groove; 3. First welding wire; 31. First part; 32. Second part; 4. Battery string manufacturing equipment; 41. Welding device; 42. Cylinder; 5. Adjacent area; 6. Second welding wire; 61. Third part; 62. Fourth part; 7. Welding wire; P. Laser reflective particles. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this disclosure clearer, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments. However, it should be understood that the specific embodiments of this disclosure are only for explaining this disclosure and are not intended to limit the scope of protection of this disclosure.

[0028] In the description of this disclosure, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," etc. (if any), indicating orientation or positional relationship, are only for the convenience of describing this disclosure with reference to the accompanying drawings and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying any order or relative importance.

[0029] Figure 1 This is a schematic diagram illustrating a battery string manufacturing apparatus in the prior art. Note that... Figure 1 The battery string manufacturing equipment shown is merely an example; other battery string manufacturing equipment exists in the prior art, such as equipment that uses a support platform instead of a cylinder to carry and transport the battery cells. The battery cell carrying and welding equipment are known and will not be described in detail herein.

[0030] like Figure 1 As shown, the battery string manufacturing equipment 4 includes a welding device 41, a cylinder 42, and a laser cutting device (not shown). The cylinder 42 is used to carry and transport battery cells 1, with multiple battery cells 1 arranged in a row on the cylinder 42. Welding wires 7 are applied to the grid lines of the current collection layer on the battery cells 1. The welding device 41 heats the welding wires 7 to weld them together with the grid lines. The laser cutting device alternately breaks the welding wires between the battery cells 1, causing all the battery cells to be connected in series, ultimately forming a series-connected battery string.

[0031] use Figure 1The battery string manufacturing equipment 4 can perform a cylindrical wire winding and welding method. This method includes the following steps: S1, placing the battery cells 1 flat and adsorbing them onto the surface of the cylinder 42 with their electrode surfaces facing outwards, so that the battery cells 1 are arranged in a row, with the electrodes of adjacent battery cells 1 at the same position flush with each other and opposite to each other. When the battery string is in back-to-back contact, all electrodes of the battery string are located on the back side of the battery cells, thus the back side of the battery cell is the electrode surface of the battery cell; S2, winding welding wire 7 around the surface of the cylinder 42, so that each welding wire 7 completely covers the current collection on the electrode surface of the battery cell 1. S3. When the cell 1 is conveyed to the welding device 41, the cell 1 and the corresponding welding wire 7 are heated and welded sequentially, thereby welding the welding wire 7 to the corresponding grid line of the cell 1; S4. Using a laser from the laser breaking device, the welding wire 7 is broken alternately at each cell spacing position, so that all the cells 1 are connected in series to form a cell string; S5. The cell string is removed, and all the welding wires with the same electrode are connected using a conductive connecting strip. The conductive connecting strip and the welding wires with opposite electrodes are isolated with insulating material to prevent short circuits. Then, subsequent module encapsulation processes can be performed as needed, such as assembling the back glass, back film, etc.

[0032] In the laser breaking step of the aforementioned method for welding and stringing solar cells, if the laser energy is not properly controlled, the laser energy will reach solar cell 1, which can easily cause microcracks, burn-through holes, or thermal damage to the anti-reflective film of solar cell 1. This will severely reduce the output power and long-term reliability of the solar module. Furthermore, if the conductive waste wires after laser breaking are scattered on the surface of solar cell 1, especially between solar cells 1 arranged closely under negative spacing conditions, short circuits can easily form, causing the solar module to fail and thus reducing the product yield.

[0033] Figure 10 This is a plan view of a battery string according to the present disclosure. Figure 11 yes Figure 10 An enlarged view of portion A of the battery string. According to this disclosure, a battery string 10 is provided. As... Figure 10-11As shown, the battery string 10 includes a first battery cell 11, a second battery cell 12, a first welding wire 3, a second welding wire 6, and a protective film 2. The first battery cell 11 and the second battery cell 12 are arranged adjacent to each other and form adjacent regions 5, as shown by the dotted lines in the figure. The first welding wire 3 includes a first portion 31 and a second portion 32. The first portion 31 is connected to the grid lines of the first battery cell 11 with a first polarity. The second portion 32 is connected to the grid lines of the second battery cell 12 with a second polarity. The first portion 31 and the second portion 32 are spaced apart from each other in the adjacent regions 5. The second welding wire 6 includes a third portion 61 and a fourth portion 62. The third portion 61 is connected to the grid lines of the first battery cell 11 with a second polarity, and the fourth portion 62 is connected to the grid lines of the second battery cell 12 with a first polarity, and the third portion 61 and the fourth portion 62 are connected to each other in the adjacent regions 5. In the thickness direction of the battery string 10, the protective film 2 is located at least between the first welding wire 3 and the adjacent regions 5.

[0034] The protective film 2 is used to provide local protection of the battery cell and / or easy removal of waste wire when the first welding wire 3 is broken by the laser. Figure 2-9 Multiple embodiments of the protective film according to the present disclosure are shown, wherein Figure 2-3 A protective film according to a first embodiment of the present disclosure is shown. Specifically, Figure 2 This is a plan view showing a protective film according to a first embodiment of the present disclosure. Figure 3 It shows Figure 2 The diagram shown is a cross-sectional view taken along line III-III of the protective film according to this disclosure.

[0035] like Figure 2-3 As shown, the protective film 2 according to this disclosure is a high-temperature resistant, high-reflectivity film strip, and includes a substrate layer 20. The specific dimensions of the protective film 2 are not particularly limited, but can be appropriately selected according to the size of the solar cell, the arrangement of the solar cells, etc. For example, the width of the protective film 2 can be 1-5 mm, the thickness can be 0.05-0.5 mm, and its length is equal to the longitudinal length of the solar cell. The substrate layer 20 of the protective film 2 is configured to withstand the energy impact during the laser breaking of the first welding wire 3.

[0036] The material of the substrate layer 20 is not limited, and can be any high-temperature resistant material such as polyimide (PI), polyethylene cyclohexyl dicarboxylate (PCT), high-temperature resistant nylon (PA9T), polyphenylene sulfide (PPS), and polyethylene naphthalate (PEN). Preferably, the material of the substrate layer 20 is a polyimide substrate. Polyimide is a high-temperature resistant polymer material that can withstand high thermal shocks in the short term, such as the instantaneous thermal shock generated during laser processing of battery cells, ensuring that the protective film 2 itself maintains structural integrity and functional continuity during the process of wire breakage, thereby preventing the formation of waste wire adhesion.

[0037] An attachment portion 21 is provided on one side of the substrate layer 20 in the thickness direction, i.e., on the lower surface shown in the figure. The shape of the attachment portion 21 is not limited; for example, it can be discrete or a continuous layer. The type of attachment portion 21 is not particularly limited; for example, it can be adhesive or other attachment methods. Preferably, the attachment portion 21 is made of an adhesive, preferably a hot melt adhesive or pressure-sensitive adhesive. The hot melt adhesive is preferably EVA adhesive or POE adhesive. When made of adhesive, the attachment portion 21 can be discrete adhesive dots or a continuous adhesive layer. The attachment portion 21 can attach the protective film 2 to an article, such as a battery cell, when properly heated or pressed.

[0038] On the other side of the substrate layer 20, i.e., the upper surface shown in the figure, a plurality of recesses are provided. The opening size of the recesses is typically on the micrometer scale; therefore, the recesses may also be referred to herein as microstructures. The size of the recesses is designed such that when the waste wire formed by the first welding wire 3 is cut falls onto the protective film 2, the recesses can reduce the contact area and adhesion between the protective film 2 and the waste wire, effectively preventing the waste wire from being electrostatically adsorbed onto the surface of the protective film 2. The construction of the recesses is unrestricted and can be as follows: Figure 2-3 As shown, the recessed portion has the form of a pit 22. The shape of the cross-section of the pit 22 perpendicular to the thickness direction is not limited; it can be a standard circle or a non-circular shape, such as a polygonal shape. Polygonal shapes include, for example, squares, trapezoids, etc. Furthermore, the method of preparing the recessed portion is not limited; for example, the recessed portion can be prepared on the surface of the protective film 2 or its substrate layer 20 by imprinting or etching processes.

[0039] Specifically, such as Figure 2 As shown, a plurality of pits 22 are provided on the surface of the substrate layer 20 of the protective film 2, specifically on the ground surface. The arrangement of the plurality of pits 22 is not limited, for example, forming a matrix with multiple rows and columns. Each pit 22 has a circular cross-section perpendicular to the thickness direction, and its opening size, i.e., diameter, is less than 100 μm, for example, 10-30 μm. The depth of the pits 22 is not particularly limited, for example, 15-20 μm. The distribution of the pits 22 is not limited, for example, preferably approximately uniformly distributed on the surface of the substrate layer 20.

[0040] The substrate layer 20 can be modified by adding additives and fillers to improve its reflectivity to lasers. Specifically, the protective film 2 includes laser-reflecting particles P, which are mixed in or within the substrate layer 20. The laser-reflecting particles P are high-reflectivity particles. The laser-reflecting particles P are dispersed approximately uniformly within the substrate layer 20. The portion of the substrate layer 20 with recesses in the thickness direction can be referred to herein as an anti-adhesion functional layer. Due to the presence of the laser-reflecting material P, the portion of the substrate layer 20 in the thickness direction other than the anti-adhesion functional layer can be referred to herein as a reflective functional layer / high-reflectivity functional layer. That is, an anti-adhesion functional layer and a reflective functional layer are formed on opposite sides of the substrate layer 20 in the thickness direction, respectively.

[0041] Preferably, the laser-reflecting particles P are mixed in the substrate layer 20 to make the reflective functional layer white or other high-reflectivity colors such as light yellow, so as to reflect as much laser light as possible. The material of the laser-reflecting particles P is not particularly limited, as long as it enables the reflective functional layer formed in the substrate layer 20 to have a higher laser reflectivity than the substrate layer 20 itself. For example, the laser-reflecting particles P can be titanium dioxide (TiO2). Adding TiO2 as a filler to the substrate layer 20 not only provides the high reflectivity of the high-temperature resistant substrate layer 20, but may also further enhance the thermal stability of the material. The size of TiO2 particles is typically around 200-300 nm. TiO2 particles can be uniformly dispersed in the substrate layer as native particles, with each particle independently and effectively scattering light, resulting in high whiteness, high hiding power, and high reflectivity. To improve the dispersion of TiO2 in each part of the substrate layer, the surface of the TiO2 particles can be coated, for example, with a nanoscale layer of silicon dioxide (SiO2) or alumina (Al2O3). Alternatively, the laser-reflecting particle P can be barium sulfate (BaSO4).

[0042] Figure 4-5 A protective film according to a second embodiment of the present disclosure is shown. Specifically, Figure 4 This is a plan view showing the protective film according to the second embodiment of the present disclosure. Figure 5 It shows Figure 4 The diagram shown is a cross-sectional view taken along line VV of the protective film according to this disclosure. The protective film according to the second embodiment is substantially the same as the protective film according to the first embodiment, except that the shape of the recessed portion is different. For the sake of brevity, the description of the identical parts is omitted.

[0043] like Figure 4As shown, the substrate layer 20 of the protective film 2 has multiple recesses on one side of its thickness direction, specifically on its ground surface. These recesses are in the form of pits 23. The multiple pits 23 are arranged in multiple rows and columns. Each pit 23 has a rectangular cross-section perpendicular to its thickness direction, and the length of the rectangle can be at an angle to the longitudinal direction of the substrate layer 20. For example, it can be perpendicular to the longitudinal direction of the substrate layer 20, parallel to the longitudinal direction of the substrate layer 20, or at an angle of approximately 30-60 degrees, such as 30, 40, 45, 50, 55, or 60 degrees. The opening width of the pit 23 is less than 100 μm, for example, it can be 10-30 μm. The depth of the pit 23 is not particularly limited, for example, it can be 15-20 μm. It is easy to understand that when the above-mentioned recess has, for example, a polygonal shape, the maximum width of the opening of the recess can be 10-30 μm, and its depth is not particularly limited, for example, 15-20 μm.

[0044] Figure 6-7 A protective film according to a third embodiment of this disclosure is shown. Specifically, Figure 6 This is a plan view showing the protective film according to the third embodiment of the present disclosure. Figure 7 It shows Figure 6 The diagram shown is a cross-sectional view taken along line VII-VII of the protective film according to this disclosure. The protective film according to the third embodiment is substantially the same as the protective film according to the first and second embodiments, except that the form of the recessed portion is different. For the sake of brevity, the description of the identical portions is omitted.

[0045] like Figure 6 As shown, on one side of the substrate layer 20 of the protective film 2 in the thickness direction, specifically on the ground surface, a plurality of recesses are provided, each recess in the form of a groove 24. Each groove 24 is elongated, and the plurality of grooves 24 are parallel to each other and spaced apart along the width direction perpendicular to the length direction of the groove 24. The length of each groove 24 is perpendicular to the longitudinal direction of the protective film 2, or parallel to the width direction of the protective film 2. Alternatively, each groove 24 may be at an angle to the width direction of the protective film 2. The opening width of the groove 24 is less than 100 μm, for example, it can be 10-30 μm. The depth of the groove 24 is not particularly limited, for example, it is 15-20 μm. The opening length of the groove 24 can be less than the width of the protective film 2.

[0046] Figure 8-9 A protective film according to a fourth embodiment of this disclosure is shown. Specifically, Figure 8 This is a plan view showing the protective film according to the fourth embodiment of the present disclosure. Figure 9 It shows Figure 8The diagram shown is a cross-sectional view taken along line IX-IX of the protective film according to this disclosure. The protective film according to the fourth embodiment is substantially the same as the protective films according to the first to third embodiments, except that the shape of the recessed portion is different. For the sake of brevity, the description of the identical portions is omitted.

[0047] like Figure 8 As shown, a plurality of grooves 25 are provided on one side of the substrate layer 20 of the protective film 2, specifically on the ground surface, in the thickness direction. Each groove 25 is elongated, and the plurality of grooves 25 are parallel to each other and spaced apart in the width direction perpendicular to the length direction of the groove 25. Each groove 25 is parallel to the longitudinal direction of the protective film 2 or perpendicular to the width direction of the protective film 2. Alternatively, each groove 25 may be at an angle to the longitudinal direction of the protective film 2. The opening width of the groove 25 is less than 100 μm, for example, it can be 10-30 μm. The depth of the groove 25 is not particularly limited, for example, the depth is 15-20 μm. The opening length of the groove 25 is preferably less than the length of the protective film 2.

[0048] The cross-sectional shape of the grooves along the direction perpendicular to the thickness is not particularly limited. For example, the grooves can be V-shaped and / or U-shaped. Alternatively, the grooves can be truncated V-shaped grooves. Similar to the pit array, the groove array can also effectively reduce the contact area between waste filaments and the protective film 2, reduce adhesion, and facilitate effective removal of waste filaments under airflow purging.

[0049] like Figure 10 As shown, in battery string 10, multiple battery cells (as an example) Figure 10 Three cells (including a first cell 11 and a second cell 12) are arranged in a row, for example, on a feeding cylinder or other platform. The protective film 2 according to this disclosure is attached, for example, to the electrode surface of the cell using its attachment portion 21. Specifically, the protective film 2 is attached to adjacent regions 5 of two adjacent cells, such as the first cell 11 and the second cell 12. These adjacent regions 5 are areas on the multiple cells to be laser-processed to break the welding wires. A first welding wire 3 and a second welding wire 6 cover the cell from the upper side of the protective film 2, i.e., the side of the protective film 2 facing away from the cell, wherein the first welding wire 3 and the second welding wire 6 respectively completely cover the current collection layer grid lines of the corresponding cell. The welding apparatus is configured to heat and weld the welding wires, thereby welding the welding wires together with the grid lines of the corresponding cell. Then, a laser is used to break one of the first welding wires 3 and 6, for example, the first welding wire 3. The first battery cell 11 and the second battery cell 12 have a negative spacing, meaning that the first battery cell 11 and the second battery cell 12 partially overlap each other in adjacent regions 5. The overlapping portions of the first battery cell 11 and the second battery cell 12 form adjacent regions 5.

[0050] In this scenario, when the laser acts alternately on the first welding wire 3 at the spacing between the solar cells, the high energy causes the first welding wire 3 to break or melt, resulting in all the solar cells being connected in series, thus forming a solar cell string. It is easy to understand that the laser can break at a single point on adjacent solar cells, or at two points, that is, break on one side of each of two adjacent solar cells, such as... Figure 11 As shown by "ⅹ" in the diagram. Two-point interruption is preferred to ensure complete interruption of the first welding wire 3. The laser energy passing through the first welding wire 3 and adjacent to it reaches the protective film 2 and is blocked by the protective film 2. The laser is reflected back, especially by the reflective functional layer of the protective film 2, in a direction away from the solar cell, thereby protecting the solar cell 1 and preventing microcracks, perforations, or damage to the antireflective film caused by thermal effects.

[0051] Furthermore, after the laser breaking process, the first welding wire 3 forms a non-planar contact with the surface of the protective film 2 with its recessed portion. If the surface of the protective film 2 is smooth, the waste wire forms a large-area contact with the protective film 2, resulting in a strong adsorption force. However, according to this disclosure, the surface of the protective film 2 has a recessed portion / microstructure, and the size of the recessed portion is designed to make it difficult for the waste wire to enter the recessed portion, but instead it stays on the edge of the recessed portion. As a result, the contact area between the waste wire and the protective film 2 is small, and thus the adhesion / adsorption force of the waste wire to the protective film 2 is greatly reduced. Therefore, only a low-pressure airflow needs to be applied to further destroy the adsorption force, thereby allowing the waste wire debris of the first welding wire 3, whose adhesion has been greatly reduced, to easily detach from the surface of the protective film 2 and be efficiently and thoroughly removed, eliminating the risk of short circuit of the battery cell caused by the residue of conductive waste wire. In summary, since the surface of the protective film 2 has recesses / microstructures such as pits or grooves, the contact area between the waste filaments and the protective film 2 is reduced on the one hand, and the airflow further breaks the adsorption force between the waste filaments and the protective film 2 by blowing air, thereby making it easy to remove the waste filaments.

[0052] As described above, the recess / microstructure includes pits or grooves. Furthermore, for ease of manufacturing, regularly arranged or patterned arrays of pits and / or grooves are preferred. The specific dimensions of the recess can be appropriately selected based on the waste wire size, as long as the waste wire does not easily enter the recess. For example, when the waste wire length is approximately 0.1 mm, the maximum opening size (for pits) or opening width (for grooves) of the recess is on the order of micrometers, such as 10-30 μm.

[0053] Figure 12 This is a flowchart illustrating a method for fabricating a battery string according to the present disclosure. The following will refer to... Figure 12 The present invention describes in detail the method for preparing the battery string, and the implementation of local protection of the battery cells and removal of waste filaments using a protective film.

[0054] Step S1: Provide a first battery cell 11 and a second battery cell 12. The first battery cell 11 and the second battery cell 12 are placed adjacent to each other and form an adjacent region 5 between them. The first battery cell 11 and the second battery cell 12 may have a negative spacing, that is, the first battery cell 11 and the second battery cell 12 are partially stacked on top of each other, and the overlapping parts form an adjacent region 5.

[0055] Step S2: Apply the protective film 2 to the adjacent area 5 of the first battery cell 11 and the second battery cell 12.

[0056] Specifically, a high-temperature resistant, high-reflectivity protective film 2 is provided in advance. A high-temperature resistant material, such as PI, with a width of 1-5 mm and a thickness of 0.05-0.5 mm is selected as the substrate layer 20 of the protective film 2. An attachment portion 21, preferably a hot melt adhesive layer or a pressure-sensitive adhesive layer, is provided on one surface in the thickness direction of the high-temperature resistant substrate layer 20 as an adhesive layer to bond the protective film 2 to the battery cell. The thickness of the attachment portion 21 or the adhesive layer can be substantially the same as the thickness of the protective film 2, for example, about 50 μm. It is understood that the thickness of the adhesive layer is selected as needed. Furthermore, a recess is formed on the other surface in the thickness direction of the high-temperature resistant substrate layer 20 by processes such as embossing or etching, forming a microstructure layer or an anti-adhesion functional layer. Preferably, laser reflective particles P are mixed into the high-temperature resistant substrate layer 20, making the side of the substrate layer 20 opposite to the anti-adhesion functional layer white or light yellow, thereby forming a reflective functional layer. The laser reflective particles P are, for example, titanium dioxide or barium sulfate. An attachment portion 21 is disposed on the reflective functional layer. Then, a protective film 2 is disposed on the adjacent region 5 of the first battery cell 11 and the second battery cell 12, wherein the attachment portion 21 attaches the protective film 2 to the adjacent region 5 of the first battery cell 11 and the second battery cell 12.

[0057] Step S3: Lay the first welding wire 3 and the second welding wire 6, and use a laser to cut the first welding wire 3 located in the adjacent area 5 to form the first part 31 and the second part 32. The laser energy passing through the first welding wire 3 and the area next to the first welding wire 3 reaches the protective film 2 and is blocked by the protective film 2.

[0058] Below, we will refer to Figure 1 The battery string manufacturing equipment 4 shown above will be used to describe steps S1-S3 in detail. A first battery cell 11 and a second battery cell 12 are sequentially laid on a feeding cylinder 42, wherein the battery cells can be arranged with positive or negative spacing. A pre-provided protective film 2 is attached to the adjacent area 5 between adjacent battery cells by appropriate pressing or heating, ensuring that the side of the protective film 2 with the anti-adhesion functional layer faces upwards (away from the battery cell) and the reflective functional layer faces downwards (towards the battery cell).

[0059] The first welding wire 3 and the second welding wire 6 are alternately applied to the current collection layer grid lines of the solar cell. Specifically, refer to... Figure 10 The entire first welding wire 3 is connected to the grid line with the first polarity of the first battery cell 11 and the grid line with the second polarity of the second battery cell 12. The entire second welding wire 6 is connected to the grid line with the second polarity of the first battery cell 11 and the grid line with the first polarity of the second battery cell 12.

[0060] Using a welding device, all the first welding wires 3 are welded to the current collection layer grid lines of the corresponding battery cells.

[0061] A laser is used to irradiate the first welding wire 3 at adjacent regions 5. The high energy of the laser causes the first welding wire 3 to be precisely melted at adjacent regions 5. During the laser wire-breaking process, the laser energy passing through or leaking from the first welding wire 3 irradiates the protective film 2 below. According to this disclosure, since the substrate layer 20 of the protective film 2 is formed of a high-temperature resistant material and preferably mixed with laser reflective particles P, the substrate layer 20 and the laser reflective particles P efficiently reflect most of the incident laser energy back. Thus, the energy passing through the first welding wire 3 and the energy next to the first welding wire is blocked by the protective film 2, significantly attenuating the energy transmitted to the main body of the solar cell, thereby preventing the solar cell from developing microcracks, perforations, or damage to the anti-reflection film due to thermal effects, and protecting the solar cell.

[0062] Step S4: Remove waste filaments

[0063] After the laser breaking step is completed, the broken waste filaments are scattered on the upper surface of the protective film 2. Because the upper surface of the protective film 2 has recesses (such as...), Figure 2-9 As shown in the diagram, this recess greatly reduces the actual contact area between the waste filaments and the protective film 2, and effectively prevents the waste filaments from adhering to the surface of the protective film 2 due to static electricity or molten splashing. At this time, by applying a low-pressure airflow to the surface of the protective film 2 for purging, the waste filaments can be easily detached from the surface of the protective film 2 and efficiently and thoroughly removed, thereby eliminating the risk of short circuits in the battery cells caused by the residue of conductive waste filaments.

[0064] After the waste wires are removed, the battery strings are conveyed to the next station for other processes such as packaging.

[0065] Variations

[0066] In the above embodiments, such as Figure 1 As shown, the welding device is a cylindrical welding device, and the cell support device is a feeding cylinder. However, the support device is not limited to the above embodiment. Alternatively, in a modified embodiment, the support device is a feeding platform, such as a circulating platform.

[0067] The above description is merely a preferred embodiment of this disclosure and is not intended to limit the scope of this disclosure. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of this disclosure, and such improvements and modifications should also be considered within the protection scope of this disclosure.

Claims

1. A battery string (10), characterized in that, The battery string (10) includes: First battery cell (11); The second battery cell (12) and the first battery cell (11) are arranged adjacent to each other and form an adjacent area (5) between them. The first welding wire (3) includes a first portion (31) connected to the grid line of the first battery cell (11) having a first polarity and a second portion (32) connected to the grid line of the second battery cell (12) having a second polarity, the first portion (31) and the second portion (32) being spaced apart from each other in the adjacent region (5); The second welding wire (6) includes a third portion (61) connected to the grid lines of the first battery cell (11) having a second polarity and a fourth portion (62) connected to the grid lines of the second battery cell (12) having a first polarity, the third portion (61) and the fourth portion (62) being connected to each other in the adjacent region (5); and A protective film (2) is located between the first welding wire (3) and the adjacent region (5).

2. The battery string (10) according to claim 1, characterized in that, The protective film (2) includes: Substrate layer (20); and An attachment portion (21) is disposed on the surface of the substrate layer (20) on the side facing the adjacent region (5) in the thickness direction and is bonded to the adjacent region (5). A recess is provided on the side opposite to the first side in the thickness direction of the substrate layer (20).

3. The battery string (10) according to claim 2, characterized in that, The recessed portion includes multiple pits (22, 23) and / or multiple grooves (24, 25).

4. The battery string (10) according to claim 3, characterized in that, Each of the recesses (22, 23) has a cross-section perpendicular to the thickness direction that is circular, square, or trapezoidal, and the plurality of recesses (22, 23) are arranged in a matrix. and / or The opening size of each of the said pits (22, 23) is 10-30 μm.

5. The battery string (10) according to claim 3, characterized in that, Each of the grooves (24, 25) is elongated, and the plurality of grooves (24, 25) are parallel to each other and spaced apart along the width direction perpendicular to the length direction of the grooves (24, 25). and / or The opening width of each of the grooves (24, 25) is 10-30 μm.

6. The battery string (10) according to claim 2, characterized in that, The material of the substrate layer (20) is one of polyimide, polyethylene cyclohexyl dicarboxylate, nylon, polyphenylene sulfide, and polyethylene naphthalate.

7. The battery string (10) according to any one of claims 1-6, characterized in that, The protective film (2) includes laser reflective particles (P), which are uniformly mixed in the substrate layer (20).

8. The battery string (10) according to claim 7, characterized in that, The material of the laser reflective particles (P) is titanium dioxide or barium sulfate.

9. The battery string (10) according to claim 2, characterized in that, The attachment portion (21) includes a plurality of discrete attachment portions or a continuous attachment layer; and / or The material of the attachment (21) includes hot melt adhesive or pressure-sensitive adhesive. Preferably, the first battery cell (11) and the second battery cell (12) are partially stacked on top of each other in the adjacent region (5).

10. A method for preparing a battery string, characterized in that, Includes the following steps: A first battery cell (11) and a second battery cell (12) are provided, wherein the first battery cell (11) and the second battery cell (12) are placed adjacent to each other and form an adjacent area (5) between them. The protective film (2) is placed on the adjacent area (5) of the first battery cell (11) and the second battery cell (12); Lay the first welding wire (3) and the second welding wire (6), and use a laser to cut the first welding wire (3) located in the adjacent area (5) to form the first part (31) and the second part (32); and An airflow is applied to sweep the adjacent area (5), causing the waste wire generated by the laser cutting the first welding wire (3) in the adjacent area (5) to fall off the surface of the protective film (2).

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