A battery cell stringing device and method

Abstract

The application provides a battery piece stringing device and a stringing method, wherein the battery piece stringing device comprises a welding conveying belt, a stringing mechanism, a glue curing mechanism and a low-temperature welding mechanism; the stringing mechanism is used for arranging the battery piece without main grid and the welding belt on the welding conveying belt to form a battery string to be cured and welded; the welding conveying belt is used for conveying the arranged battery piece without main grid and the welding belt to the glue curing mechanism and the low-temperature welding mechanism in sequence; the glue curing mechanism is used for curing the adhesive to bond the welding belt to the corresponding battery piece without main grid; and the low-temperature welding mechanism is used for implementing low-temperature heating on the welding belt to melt the solder on the welding belt, so that the alloying connection between the welding belt and the auxiliary grid line is formed and the battery string is formed. The battery piece stringing device provided by the application can perform low-temperature welding after the welding belt and the battery piece without main grid are bonded by the adhesive, so that the functional film does not need to be arranged during lamination, and the battery string is convenient to repair after low-temperature welding.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery production, in particular to a battery piece stringing device and a stringing method. BACKGROUND

[0002] The high-temperature welding method is used to implement the stringing of 0BB battery pieces (i.e., battery pieces without main grids), which can damage the film on the surface of the battery pieces. Therefore, the low-temperature welding method is generally used to implement the stringing of 0BB battery pieces. The solder strip used is a low-temperature solder strip.

[0003] Currently, the low-temperature welding method is as follows: first, a glue point is applied to the surface of the battery piece; then, the solder strip is arranged in the battery piece to preliminarily adhere the solder strip to the battery piece through the glue point, thereby forming a battery string; then, the battery string is arranged and the bus bar is welded; finally, during the lamination of the assembly, the tin on the low-temperature solder strip is melted through lamination heating, thereby forming an alloyed connection between the solder strip and the sub-grid lines of the battery piece. However, the current low-temperature welding method has the following disadvantages: 1) In order to prevent the melted EVA film from entering the space between the solder strip and the sub-grid lines during lamination and affecting the alloyed connection between the solder strip and the sub-grid lines, a functional film needs to be laid on the outside of the solder strip to isolate the EVA, thereby increasing the cost of the assembly; 2) After lamination, it cannot be guaranteed that the solder strip and all the sub-grid lines of the battery piece in each battery string in the assembly can form an alloyed connection. If there is a solder strip that does not form an alloyed connection with the sub-grid lines of the battery piece, since the assembly has been laminated at this time, it is difficult to repair, and the entire assembly may need to be scrapped. SUMMARY

[0004] To solve the above technical problems, the present application provides a battery piece stringing device, which adopts the following technical solutions:

[0005] A battery piece stringing device is used to string a plurality of battery pieces without main grids into a battery string. An adhesive is applied to the surface of the battery piece without main grids along a solder strip laying path. The battery piece stringing device comprises a welding conveyor belt, a stringing mechanism, a glue curing mechanism, and a low-temperature welding mechanism, wherein:

[0006] The stringing mechanism is used to arrange the battery piece without main grids and the solder strip on the welding conveyor belt according to a predetermined stringing rule to form a battery string to be cured and welded. The solder strip is arranged on the solder strip laying path and perpendicularly intersects each sub-grid line on the surface of the corresponding battery piece without main grids.

[0007] The welding conveyor belt is used to sequentially convey the laid battery piece without main grids and the solder strip to the glue curing mechanism and the low-temperature welding mechanism. The glue curing mechanism is used to cure the adhesive, so that the solder strip is adhered to the corresponding battery piece without main grids through the adhesive. The low-temperature welding mechanism is used to implement low-temperature heating of the solder strip to melt the solder on the solder strip, so that an alloyed connection is formed between the solder strip and the sub-grid lines and a battery string is formed.

[0008] The battery piece stringing device provided by the application forms an alloying connection between the welding band and the sub-grid line of the battery piece without main grid after the welding band is glued to the battery piece without main grid, so that the battery piece string is formed. Since the alloying connection has been formed between the welding band and the sub-grid line, the functional film does not need to be isolated from EVA during the later lamination, thereby reducing the cost. In addition, the battery piece string is detected after the low-temperature welding, and the unqualified battery piece string can be repaired in time, so that the repair is convenient and the repair cost is low.

[0009] In some embodiments, the adhesive is UV-cured glue, and the glue curing mechanism at least includes a first UV lamp box arranged above the welding conveying belt.

[0010] When the adhesive is UV-cured glue, the upper surface of the battery piece without main grid is irradiated with UV light by the first UV lamp box, so that the adhesive on the upper surface of the battery piece without main grid is cured, and the welding band on the upper surface is glued to the battery piece without main grid.

[0011] In some embodiments, the welding conveying belt is a light-transmitting conveying belt, and the glue curing mechanism further includes a second UV lamp box arranged below the welding conveying belt.

[0012] The welding conveying belt is arranged as a light-transmitting conveying belt, and the lower surface of the battery piece without main grid is irradiated with UV light by the second UV lamp box arranged below the welding conveying belt, so that the welding band on the lower surface is glued to the corresponding battery piece without main grid.

[0013] In some embodiments, the adhesive is heat-cured glue, and the glue curing mechanism at least includes a heating lamp box arranged above the welding conveying belt.

[0014] When the adhesive is heat-cured glue, the battery piece without main grid is heated by the heating lamp box arranged above the welding conveying belt, so that the welding band is glued to the battery piece without main grid.

[0015] In some embodiments, the glue curing mechanism further includes a heating plate arranged below the welding conveying belt.

[0016] The heating plate arranged below the welding conveying belt can cooperate with the heating lamp box to heat the battery piece without main grid, thereby improving the gluing efficiency and gluing effect of the welding band.

[0017] In some embodiments, the low-temperature welding mechanism includes an infrared lamp box arranged above the welding conveying belt, the infrared lamp box is arranged close to the welding conveying belt, the heating temperature of the infrared lamp box to the welding band is lower than 200℃, and the heating time of the infrared lamp box to the welding band in the same group is 2s-20s.

[0018] Since gridless solar cells are not suitable for high-temperature welding, low-temperature welding strips are used. By setting the heating temperature below 200℃, the heating temperature is only slightly higher than the melting point of the solder in currently available low-temperature welding strips. This ensures that the solder melts to achieve low-temperature welding while avoiding damage to the gridless solar cells. By placing the infrared lamp box close to the welding conveyor belt, the heat loss of the infrared lamp box can be effectively reduced, ensuring the solder melting effect. By setting the heating time of the same group of welding strips to 2s to 20s, the solder has sufficient time to melt, ensuring the welding effect.

[0019] In some embodiments, the welding conveyor belt is configured to continuously transport the battery string to be cured and welded, and the heating area of ​​the low-temperature welding mechanism can cover at least three gridless cells along the transport direction of the welding conveyor belt; or the welding conveyor belt is configured to transport the battery string to be cured and welded in a stepwise manner, wherein the welding conveyor belt transports N gridless cells to the heating area of ​​the low-temperature welding mechanism in each step, where N is an integer and does not exceed the total number of gridless cells in the battery string.

[0020] For the scenario where the battery string to be cured and welded passes continuously through the heating area of ​​the low-temperature welding mechanism, by setting the length of the heating area to at least cover three grid-less cells, it can be ensured that each grid-less cell has enough time to pass through the heating area to ensure that the solder on its solder ribbon can be fully melted. For the scenario where the battery string to be cured and welded passes through the heating area of ​​the low-temperature welding mechanism in a step-by-step manner, by stepping N grid-less cells into the heating area each time and staying for a sufficient time, it can be ensured that the solder on its solder ribbon can be fully melted. Setting N to an integer can avoid the same cell being heated multiple times. Setting N to not exceed the total number of grid-less cells in the battery string means that the length of the low-temperature welding mechanism does not need to be set too long, which can save equipment space while meeting production requirements.

[0021] In some embodiments, the stringing mechanism includes a cell placement section and a ribbon placement section. The cell placement section is used to place the gridless cells onto the welding conveyor belt according to a predetermined stringing rule, and the ribbon placement section is used to place the ribbon onto the welding conveyor belt according to a predetermined stringing rule. The stringing mechanism also includes a tooling transfer mechanism and a ribbon pressing tooling. The tooling transfer mechanism places the ribbon pressing tooling onto the gridless cells on the welding conveyor belt where the ribbons are placed, so as to press the ribbons onto the gridless cells below.

[0022] By using a tooling transfer mechanism to press the welding strip clamping tool onto the gridless solar cell, the welding strip can be pressed firmly onto the gridless solar cell, thereby improving the subsequent adhesive bonding and welding effect and preventing weak adhesion and incomplete welding. Through the cooperation of the solar cell placement section and the welding strip placement section, the stringing mechanism can alternately place the gridless solar cell and the welding strip onto the welding conveyor belt to form a battery string to be cured and welded, thereby improving the stringing efficiency.

[0023] The present invention also provides a method for stringing solar cells, which is used to string together several gridless solar cells into a solar cell string. Adhesive is applied at intervals along a path laid on the surface of the gridless solar cells. The method for stringing solar cells includes:

[0024] The gridless solar cells and solder ribbons are arranged according to the predetermined stringing rules to form a battery string to be cured and welded. The solder ribbons are laid on the solder ribbon laying path and intersect perpendicularly with each sub-grid line on the surface of the corresponding gridless solar cell.

[0025] The pre-arranged grid-less solar cells and solder ribbons are cured so that the solder ribbons are bonded to the corresponding grid-less solar cells with adhesive.

[0026] The solder ribbons bonded to the gridless solar cells with adhesive are subjected to low-temperature heating to melt the solder on the solder ribbons, so that an alloyed connection is formed between the solder ribbons and the sub-grid lines to form a battery string;

[0027] The appearance quality and EL test were performed on the battery string after low-temperature heating.

[0028] The battery cell stringing method provided by this invention involves bonding the solder ribbon to the gridless battery cell, followed by low-temperature welding of the solder ribbon to connect the gridless battery cells in series to form a battery string. The formed battery string is then subjected to appearance quality inspection and EL inspection. This operation has two advantages: firstly, it can promptly identify defective battery strings, facilitating timely rework and preventing defective battery strings from flowing into subsequent processes; secondly, since an alloyed connection has already been formed between the solder ribbon and the sub-busbar lines of the gridless battery cell, there is no need to install a functional membrane (EVA) for isolation during subsequent lamination, thereby reducing costs.

[0029] In some embodiments, the predetermined string arrangement rule is as follows: the i-th gridless cell is stacked on the upper side of the latter half of the i-th group of solder ribbons, and the first half of the (i+1)-th group of solder ribbons is stacked on the upper surface of the i-th gridless cell, where i is any natural number greater than 0; or, the predetermined string arrangement rule is as follows: the latter half of the i-th group of solder ribbons is stacked on the upper surface of the i-th gridless cell, and the first half of the i-th group of solder ribbons is stacked on the upper surface of the (i-1)-th gridless cell, where i is any natural number greater than 1 and less than N+1, and N is the total number of gridless cells in the cell string.

[0030] By setting predetermined stringing rules, it can be ensured that both gridless solar cells with only one welding surface and gridless solar cells with welding surfaces on both sides can be strung together.

[0031] In some embodiments, the adhesive is a UV-curable adhesive, and curing the adhesive includes: irradiating the adhesive with UV light to cure the adhesive; or, the adhesive is a thermosetting adhesive, and curing the adhesive includes: heating the adhesive to cure the adhesive.

[0032] The adhesive is a UV-curable adhesive, which is used to bond the solder ribbon to the corresponding solar cell by UV light curing; the adhesive is a thermosetting adhesive, which is used to bond the solder ribbon to the corresponding solar cell by heat curing.

[0033] In some embodiments, the heating temperature of low-temperature heating is below 200°C, and the heating time for the same group of welding strips at low temperature is 2s to 20s.

[0034] Since gridless solar cells are not suitable for high-temperature welding, low-temperature welding strips are used. By setting the heating temperature below 200℃, which is slightly higher than the melting point of the solder in currently available low-temperature welding strips, the welding strips can be made to melt the solder and achieve low-temperature welding, while avoiding damage to the gridless solar cells. By placing the infrared lamp box close to the welding conveyor belt, the heat loss of the infrared lamp box can be effectively reduced, ensuring the melting effect of the solder. By setting the heating time of the same group of welding strips to 2s to 20s, the solder can be allowed sufficient time to melt, ensuring the welding effect.

[0035] In some embodiments, after performing appearance quality inspection and EL inspection on the battery strings after low-temperature heating, the battery cell stringing method further includes: sequentially arranging the qualified battery strings, stacking busbars, and laminating them, wherein the lamination heating temperature is lower than the melting temperature of the solder on the solder strip.

[0036] Since an alloyed bond has already been formed between the solder strip and the sub-gate line, setting the heating temperature during lamination to be lower than the melting temperature of the solder on the solder strip can prevent secondary welding of the solder strip. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a battery cell stringing device in one embodiment of the present invention after omitting some components;

[0038] Figure 2 This is a schematic diagram of the structure of the battery cell stringing device in another embodiment of the present invention after omitting some components;

[0039] Figure 3 This is a schematic diagram of a battery string arranged for curing and welding in one embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the battery strings arranged for curing and welding in another embodiment of the present invention;

[0041] Figures 1 to 4 Includes:

[0042] Welding conveyor belt 1;

[0043] Adhesive curing mechanism 2:

[0044] First UV light box 21, second UV light box 22;

[0045] Heating lamp box 23, heating plate 24;

[0046] Low-temperature welding mechanism 3:

[0047] Clamping fixture 4. Detailed Implementation

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] To address the shortcomings of current low-temperature welding of grid-less solar cells, this invention provides a solar cell stringing device for connecting several grid-less solar cells into a battery string, wherein adhesive is applied at intervals along the welding strip laying path on the surface of the grid-less solar cells.

[0050] like Figure 1 and Figure 2 As shown, the battery cell stringing device in this embodiment of the invention includes a welding conveyor belt 1, a stringing mechanism (not shown in the figure), an adhesive curing mechanism 2, and a low-temperature welding mechanism 3, wherein:

[0051] The stringing mechanism is used to arrange the gridless solar cells and welding ribbons on the welding conveyor belt 1 according to a predetermined stringing rule to form a battery string to be cured and welded. The welding ribbons are laid on the welding ribbon laying path and intersect perpendicularly with each sub-grid line on the surface of the corresponding gridless solar cell.

[0052] The welding conveyor belt 1 is used to sequentially transport the laid-up gridless solar cells and welding strips to the adhesive curing mechanism 2 and the low-temperature welding mechanism 3. The adhesive curing mechanism 2 is used to cure the adhesive so that the welding strip is bonded to the corresponding gridless solar cell. The low-temperature welding mechanism 3 is used to perform low-temperature heating on the welding strip to melt the solder on the welding strip, so that the welding strip and the sub-busbars form an alloyed connection and form a battery string.

[0053] As can be seen, using the cell stringing device in this embodiment of the invention, after bonding the solder ribbon to the gridless cell, low-temperature welding can be performed immediately on the solder ribbon, so that an alloyed connection is formed between the solder ribbon and the sub-busbars of the gridless cell to form a cell string. Since an alloyed connection has been formed between the solder ribbon and the sub-busbars, there is no need to set a functional membrane EVA for isolation during subsequent lamination, thereby reducing costs; in addition, the cells can be inspected immediately after being low-temperature welded into strings, and defective cell strings can be promptly reworked, which is convenient and inexpensive.

[0054] As those skilled in the art know, based on the arrangement of the welding surfaces, grid-less solar cells are divided into two categories: The first category has sub-grid lines on both surfaces, meaning both surfaces are welding surfaces requiring solder strips. The second category has sub-grid lines on only one surface, meaning only one surface is the welding surface requiring solder strips.

[0055] The following section will specifically describe, for the two types of gridless solar cells mentioned above, the "stringing mechanism arranges the gridless solar cells and welding strips on the welding conveyor belt according to a predetermined stringing rule" in the embodiments of the present invention.

[0056] For the first type of gridless solar cell, that is, the upper and lower surfaces of the solar cell are both welded surfaces.

[0057] like Figure 3 As shown, the stringing rule of the stringing mechanism is as follows: the i-th gridless cell is stacked on the upper side of the second half of the i-th group of solder strips, and the first half of the (i+1)-th group of solder strips is stacked on the upper surface of the i-th gridless cell, where i is any natural number greater than 0.

[0058] For the second type of gridless solar cell, that is, the case where only the upper surface of the cell is a welded surface.

[0059] like Figure 4 As shown, the stringing rule of the stringing mechanism is as follows: the second half of the i-th group of solder strips is stacked on the upper surface of the i-th gridless cell, and the first half of the i-th group of solder strips is stacked on the upper surface of the (i-1)-th gridless cell, where i is any natural number greater than 1 and less than N+1, and N is the total number of gridless cells in the string.

[0060] The latter half of the first ribbon group (i.e., the head ribbon) is stacked on the first cell, and the first half of the N+1th ribbon group (i.e., the tail ribbon) is stacked on the Nth cell.

[0061] The adhesive applied to the welding surface of the gridless solar cell can be either a UV-curable adhesive or a thermosetting adhesive. When the adhesive is a UV-curable adhesive, the adhesive curing mechanism 2 is a UV light irradiation mechanism capable of generating UV light, while when the adhesive is a thermosetting adhesive, the adhesive curing mechanism 2 is a heating mechanism.

[0062] The battery stringing device of the present invention will be described exemplarily below through two embodiments.

[0063] First Embodiment

[0064] The cell stringing device in this embodiment is suitable for cases where the adhesive applied to the welding surface of gridless cells is a UV-curable adhesive.

[0065] like Figure 1 As shown, in the battery cell stringing device of this embodiment, the adhesive curing mechanism 2 includes at least a first UV lamp box 21 disposed above the welding conveyor belt 1.

[0066] Since the UV light emitted by the first UV lamp box 21 is difficult to penetrate the gridless solar cell, if the adhesive curing mechanism 2 only includes the first UV lamp box 21, it is suitable for stringing the second type of gridless solar cell described above. The specific process is as follows:

[0067] The stringing mechanism completes the stringing of the second type of gridless solar cells and the solder ribbon to form a battery string to be cured and welded, and ensures that the welding surface of the second type of gridless solar cells faces upward.

[0068] Next, the welding conveyor belt 1 transports the battery string to be cured and welded, so that the laid gridless battery cells and welding strips pass under the first UV lamp box 21. The first UV lamp box 21 emits UV light to irradiate the upper surface of the second type of gridless battery cells to cure the UV curing adhesive on them. Finally, the welding strips on the upper surface are bonded to the corresponding second type of gridless battery cells by the cured UV curing adhesive.

[0069] Next, driven by the welding conveyor belt 1, the bonded gridless solar cells and welding strips pass under the low-temperature welding mechanism 3. The low-temperature welding mechanism 3 heats the gridless solar cells and welding strips at low temperature, so that the welding strips are welded to the corresponding second type of gridless solar cells at low temperature, thus obtaining the final battery string.

[0070] As mentioned earlier, both surfaces of the first type of gridless solar cell are welded surfaces. For this type of gridless solar cell, if only the first UV lamp box 21 is installed, it is difficult to cure and bond the solder strips on the lower surface of the cell. Alternatively, after curing and bonding the solder strips on the upper surface of the cell string to be cured and welded, the cell string is flipped over before curing and bonding the solder strips on the lower surface of the cell string to be cured and welded. Such an operation will significantly reduce work efficiency.

[0071] In order to achieve efficient stringing of the first type of gridless solar cells, such as Figure 1As shown, in this embodiment of the battery cell stringing device, the adhesive curing mechanism 2 further includes a second UV lamp box 22 disposed below the welding conveyor belt 1. Thus:

[0072] Under the conveying of the welding conveyor belt 1, when the laid first type of gridless solar cell and welding strip pass over the second UV light box 22, the second UV light box 22 emits UV light to irradiate the lower surface of the first type of gridless solar cell to cure the UV curing adhesive on it, and finally the welding strip on the lower surface is bonded to the corresponding first type of gridless solar cell by the cured UV curing adhesive.

[0073] To ensure that the UV light emitted from the second UV lamp box 22 can fully illuminate the lower surface of the first type of gridless solar cell, the welding conveyor belt 1 may optionally be a light-transmitting conveyor belt. The light-transmitting conveyor belt may be, for example, a conveyor belt made of a light-transmitting material, or a conveyor belt with numerous light-transmitting holes.

[0074] Optionally, to shorten the conveying stroke of welding conveyor belt 1, such as... Figure 1 As shown, the first UV lamp box 21 and the second UV lamp box 22 are arranged opposite to each other on the upper and lower sides of the welding conveyor belt 1. When the laid first type of gridless solar cell and the welding strip pass between the first UV lamp box 21 and the second UV lamp box 22, the first UV lamp box 21 and the second UV lamp box 22 simultaneously cure the UV curing adhesive on the upper and lower surfaces of the first type of gridless solar cell.

[0075] Second Embodiment

[0076] The cell stringing device of this embodiment is applicable to cases where the adhesive applied to the welding surface of the gridless cell is a thermosetting adhesive.

[0077] like Figure 2 As shown, in this embodiment of the cell stringing device, the adhesive curing mechanism 2 includes at least a heating lamp box 23 disposed above the welding conveyor belt 1. Since the heating lamp box 23 can perform overall heating of the gridless cells, even with only the heating lamp box 23, the cell stringing device in this embodiment can meet the bonding requirements for the two types of gridless cells described above.

[0078] The working process of the battery cell stringing device in this embodiment is as follows:

[0079] The stringing mechanism completes the stringing operation of gridless solar cells and solder strips to form a battery string to be cured and welded.

[0080] Next, the welding conveyor belt 1 transports the battery string to be cured and welded, so that the laid-up gridless battery cells and welding strips pass under the heating lamp box 23. The heating lamp box 23 heats the gridless battery cells and the welding strips on them, so that the welding strips are bonded to the corresponding gridless battery cells by the cured thermosetting adhesive.

[0081] Next, the bonded gridless solar cells and solder ribbons pass under the low-temperature welding mechanism 3, which low-temperature welds the solder ribbons onto the corresponding gridless solar cells to obtain the final battery string.

[0082] Optionally, to achieve rapid heating and curing of the thermosetting adhesive, especially for the thermosetting adhesive on the lower surface of the gridless solar cell, and to improve bonding efficiency, such as... Figure 2 As shown, optionally, the battery cell stringing device in this embodiment also includes a heating plate 24 disposed below the welding conveyor belt 1. The heating plate 24 can work in conjunction with the heating lamp box 23 to heat the battery string to be cured and welded.

[0083] Continue to refer to Figure 1 and Figure 2 As shown, optionally, in the battery cell stringing device of the present invention, the low-temperature welding mechanism 3 is an infrared light box set above the welding conveyor belt 1. The infrared light box is set close to the welding conveyor belt 1, the heating temperature of the welding strip by the infrared light box is lower than 200°C, and the heating time of the welding strip in the same group by the infrared light box is 2s to 20s.

[0084] Since gridless solar cells are not suitable for high-temperature welding, low-temperature welding strips are used. By setting the heating temperature below 200℃, the heating temperature is only slightly higher than the melting point of the solder in currently available low-temperature welding strips. This ensures that the solder melts to achieve low-temperature welding while avoiding damage to the gridless solar cells. By placing the infrared lamp box close to the welding conveyor belt, the heat loss of the infrared lamp box can be effectively reduced, ensuring the solder melting effect. By setting the heating time of the same group of welding strips to 2s to 20s, the solder has sufficient time to melt, ensuring the welding effect.

[0085] Because the welding temperature is relatively low, only slightly higher than the melting temperature of the solder on the surface of the low-temperature solder strip, the low-temperature welding time needs to be selectively set to ensure that the solder on the surface of the solder strip melts completely. The low-temperature welding time is related to factors such as the welding temperature, the melting point of different types of low-temperature solder, and the thickness of the sub-grid lines. For example, when the difference between the welding temperature and the melting point of the solder is large, and the sub-grid lines are thicker, the required heating time is shorter. In practice, the heating time for the same group of solder strips can be selected from the range of 2s to 20s according to the actual situation.

[0086] In some alternative embodiments, the welding conveyor belt 1 is configured to continuously transport the battery strings to be cured and welded, so that the gridless cells pass continuously and without interruption through the heating area of ​​the cryogenic welding mechanism 3. To ensure that each cell is in the heating area for a sufficiently long time to ensure that the solder on the welding strip can fully melt, optionally, the length of the heating area of ​​the cryogenic welding mechanism 3 along the conveying direction of the welding conveyor belt 1 can cover at least three gridless cells. In actual production, the conveying speed of the welding conveyor belt 1 can be set according to the ratio of the length of the heating area of ​​the cryogenic welding mechanism 3 to the required heating time.

[0087] In some alternative embodiments, the welding conveyor belt 1 is configured to transport the battery string to be cured and welded in a step-by-step manner. Each step of the welding conveyor belt transports N grid-less solar cells to the heating area of ​​the low-temperature welding mechanism, where they remain for a predetermined duration to ensure that the solder on the solder strips on the grid-less solar cells is fully melted. Here, N is an integer and does not exceed the total number of grid-less solar cells in the battery string. The specific duration of the grid-less solar cells remaining in the heating area can be selected according to specific circumstances to ensure that the solder on the solder strips is fully melted. Preferably, N is an integer greater than or equal to 3. Taking a battery string containing 12 grid-less solar cells as an example, when N=3, the welding conveyor belt needs to step 4 times to complete the welding of one battery string; when N=6, the welding conveyor belt needs to step 2 times to complete the welding of one battery string. Setting N to an integer avoids heating the same cell multiple times; setting N to not exceed the total number of gridless cells in the cell string means that the length of the low-temperature welding mechanism does not need to be too long, saving equipment space while still meeting production needs.

[0088] Optionally, in the battery cell stringing device of this embodiment, the stringing mechanism includes a battery cell placement section and a solder ribbon placement section. The battery cell placement section is used to place the gridless battery cells onto the welding conveyor belt according to a predetermined stringing rule, and the solder ribbon placement section is used to place the solder ribbon onto the welding conveyor belt according to a predetermined stringing rule. Through the cooperation of the battery cell placement section and the solder ribbon placement section, the stringing mechanism can alternately place the gridless battery cells and solder ribbons onto the welding conveyor belt 1, thereby improving the stringing efficiency.

[0089] like Figure 1 and Figure 2 As shown, optionally, the stringing mechanism also includes a tooling transfer mechanism and a welding strip pressing tool 4. The tooling transfer mechanism places the welding strip pressing tool 4 on the gridless solar cell on the welding conveyor belt 1 where the welding strip is laid, so as to press the welding strip onto the gridless solar cell below, thereby ensuring that the welding strip is pressed onto the gridless solar cell, improving the subsequent adhesive bonding and welding effect, and preventing the occurrence of false welds.

[0090] The present invention also provides a method for stringing battery cells, which is used to string together several gridless battery cells into a battery string, wherein adhesive is applied at intervals along the path laid by the solder strip on the surface of the gridless battery cells.

[0091] The method for stringing battery cells in this embodiment of the invention includes the following steps:

[0092] S1. Arrange the gridless solar cells and solder ribbons according to the predetermined stringing rules to form a battery string to be cured and welded. The solder ribbons are laid on the solder ribbon laying path and intersect perpendicularly with each sub-grid line on the surface of the corresponding gridless solar cell.

[0093] As mentioned earlier, gridless solar cells are divided into two categories: the first type has sub-grid lines on both surfaces, meaning both surfaces are welding surfaces that require solder ribbons; the second type has sub-grid lines on only one surface, meaning only one surface is welding surfaces that require solder ribbons.

[0094] For the first type of gridless solar cell, that is, the upper and lower surfaces of the solar cell are both welded surfaces.

[0095] like Figure 3 As shown, the predetermined string arrangement rule in step S1 is: the i-th gridless cell is stacked on the upper side of the second half of the i-th group of solder strips, and the first half of the (i+1)-th group of solder strips is stacked on the upper surface of the i-th gridless cell, where i is any natural number greater than 0.

[0096] For the second type of gridless solar cell, that is, the upper surface of the solar cell is a welded surface.

[0097] like Figure 4 The predetermined string arrangement rule in step S1 is as follows: the latter half of the i-th group of solder ribbons is stacked on the upper surface of the i-th gridless cell, and the first half of the i-th group of solder ribbons is stacked on the upper surface of the (i-1)-th gridless cell, where i is any natural number greater than 1 and less than N+1, and N is the total number of gridless cells in the battery string.

[0098] The latter half of the first ribbon group (i.e., the head ribbon) is stacked on the first cell, and the first half of the N+1th ribbon group (i.e., the tail ribbon) is stacked on the Nth cell.

[0099] S2. The pre-arranged gridless solar cells and solder ribbons are cured so that the solder ribbons are bonded to the corresponding gridless solar cells with adhesive.

[0100] The adhesive can be a UV-curable adhesive or a thermosetting adhesive. When the adhesive is a UV-curable adhesive, curing the adhesive includes irradiating the adhesive with UV light to cure it. When the adhesive is a thermosetting adhesive, curing the adhesive includes heating the adhesive to cure it.

[0101] S3. The solder ribbon bonded to the gridless cell with adhesive is heated at low temperature to melt the solder on the solder ribbon, so that the solder ribbon and the sub-busbar line form an alloy connection to form a cell string.

[0102] High-temperature welding is not suitable for gridless solar cells; therefore, low-temperature welding strips are used. Optionally, the heating temperature for low-temperature heating is below 200℃. The specific heating temperature can be selected based on the melting temperature of the solder on the welding strip. For example, for low-temperature welding strips with a solder melting temperature range of 135℃-145℃, the low-temperature heating temperature can be set to 150℃-160℃; for low-temperature welding strips with a solder melting temperature range of 165℃-175℃, the low-temperature heating temperature can be set to 180℃-190℃. That is, the heating temperature is only slightly higher than the melting temperature of the solder on the surface of the low-temperature welding strip, thus melting the solder while avoiding damage to the gridless solar cell due to excessive temperature. Of course, without damaging the gridless solar cell, the heating temperature can be appropriately increased to widen the difference between the heating temperature and the solder melting point, thereby improving heating efficiency.

[0103] Since the welding temperature is only slightly higher than the melting temperature of the solder on the surface of the low-temperature solder strip, the low-temperature welding time needs to be selectively set to ensure that the solder on the surface of the solder strip melts completely. The low-temperature welding time is related to factors such as the heating temperature, the melting point of the solder of different types of low-temperature solder strips, and the thickness of the sub-grid lines on the surface of the gridless cell. For example, when the difference between the heating temperature and the melting point of the solder is large, and the sub-grid lines are thick, a shorter heating time can be set; conversely, a longer heating time is required. In practice, the heating time for the same group of solder strips can be selected from the range of 2s to 20s to ensure that the solder melts completely.

[0104] Steps S1 to S3 described above can be implemented by the battery cell stringing device provided in the embodiments of the present invention described above. For specific implementation details, please refer to the relevant descriptions above, which will not be repeated here.

[0105] After the low-temperature heating in step S3 is completed, the solder ribbon has formed an alloyed connection with the sub-busbars, and the gridless cells have been connected in series. Therefore, step S4 can be performed at this time.

[0106] S4. Perform appearance quality inspection and EL inspection on the battery strings after low-temperature heating to facilitate the rework of unqualified battery strings.

[0107] Optionally, an appearance quality inspection mechanism may be provided above the conveyor belt 1 of the battery cell stringing device in various embodiments of the present invention to perform appearance quality inspection on the battery string after low-temperature heating. The appearance quality inspection mechanism may be, for example, a camera, which performs appearance quality inspection on the battery string by taking pictures and analyzing the images.

[0108] Optionally, an EL detection mechanism can be installed above and on the side of the conveyor belt 1 to perform EL detection on the battery string after cryogenic heating. For example, the EL detection mechanism includes a conductive component located on the side of the conveyor belt and an infrared camera located above the conveyor belt 1. When the battery string reaches the detection area of ​​the conductive component under the drive of the conveyor belt 1, the conductive component flips towards the conveyor belt 1 and presses against the two end leads of the battery string to conduct electricity. The conducted battery string heats up, and the infrared camera acquires an infrared image of the heated battery string. By analyzing the infrared image, internal defects in the battery string can be detected.

[0109] Optionally, after completing step S4, the battery cell stringing method in this embodiment of the invention further includes:

[0110] S5. The qualified battery strings are arranged, busbars are stacked and laminated in sequence. The heating temperature of the lamination is lower than the melting temperature of the solder on the solder strip.

[0111] Since an alloyed connection has been formed between the solder strip and the sub-gate line after performing step S4, the heating temperature during lamination is set to be lower than the melting temperature of the solder on the solder strip. The heating temperature during lamination only needs to be sufficient to melt the EVA film, thereby preventing the solder on the solder strip from melting again and causing secondary welding of the solder strip.

[0112] The present invention has been described above in sufficient detail and with certain specificities. Those skilled in the art should understand that the descriptions in the embodiments are merely exemplary, and all changes made without departing from the true spirit and scope of the invention should fall within the protection scope of the invention. The scope of protection claimed by the present invention is defined by the claims, and not by the above descriptions in the embodiments.

Claims

1. A battery cell stringing device, characterized in that, This device is used to string together several gridless solar cells into a battery string. Adhesive is applied at intervals along the welding strip laying path on the surface of the gridless solar cells. The cell stringing device includes a welding conveyor belt, a stringing mechanism, an adhesive curing mechanism, and a low-temperature welding mechanism, wherein: The stringing mechanism is used to arrange the gridless solar cells and welding ribbons on the welding conveyor belt according to a predetermined stringing rule to form a string of cells to be cured and welded. The welding ribbons are laid on the welding ribbon laying path and intersect perpendicularly with each sub-grid line on the surface of the corresponding gridless solar cell. The welding conveyor belt is used to sequentially transport the laid-up grid-less solar cells and welding strips to the adhesive curing mechanism and the low-temperature welding mechanism. The adhesive curing mechanism is used to cure the adhesive so that the welding strips are bonded to the corresponding grid-less solar cells. The low-temperature welding mechanism is used to perform low-temperature heating on the welding strips to melt the solder on the welding strips, so that the welding strips and the sub-busbars form an alloyed connection and form a battery string. The welding conveyor belt is configured to continuously transport the battery strings to be cured and welded, and the heating zone of the low-temperature welding mechanism, along the transport direction of the welding conveyor belt, can cover at least three gridless battery cells; or The welding conveyor belt is configured to transport the battery string to be cured and welded in a stepwise manner, wherein the welding conveyor belt transports N gridless battery cells to the heating area of ​​the low-temperature welding mechanism in each step, where N is an integer and does not exceed the total number of gridless battery cells in the battery string.

2. The battery cell stringing device as described in claim 1, characterized in that, The adhesive is a UV-curable adhesive, and the adhesive curing mechanism includes at least a first UV lamp box disposed above the welding conveyor belt.

3. The battery cell stringing device as described in claim 2, characterized in that: The welding conveyor belt is a light-transmitting conveyor belt; The adhesive curing mechanism also includes a second UV lamp box located below the welding conveyor belt.

4. The battery cell stringing device as described in claim 1, characterized in that, The adhesive is a thermosetting adhesive, and the adhesive curing mechanism includes at least a heating lamp box disposed above the welding conveyor belt.

5. The battery cell stringing device as described in claim 4, characterized in that, The adhesive curing mechanism also includes a heating plate disposed below the welding conveyor belt.

6. The battery cell stringing device as described in claim 1, characterized in that, The low-temperature welding mechanism includes an infrared light box disposed above the welding conveyor belt. The infrared light box is disposed close to the welding conveyor belt. The heating temperature of the welding strip by the infrared light box is below 200°C. The heating time of the same group of welding strips by the infrared light box is 2s to 20s.

7. The battery cell stringing device as described in claim 1, characterized in that: The stringing mechanism includes a cell placement section and a ribbon placement section. The cell placement section is used to place gridless cells on the welding conveyor belt according to a predetermined stringing rule, and the ribbon placement section is used to place ribbons on the welding conveyor belt according to a predetermined stringing rule. The stringing mechanism also includes a tooling transfer mechanism and a welding strip pressing tooling. The tooling transfer mechanism places the welding strip pressing tooling on the gridless solar cell on the welding conveyor belt where the welding strip is laid, so as to press the welding strip onto the gridless solar cell below.

8. A method for stringing battery cells, characterized in that, The battery cell stringing apparatus of claim 1 is used to string together a plurality of gridless battery cells into a battery string, wherein adhesive is applied at intervals along the solder strip laying path on the surface of the gridless battery cells, and the battery cell stringing method includes: The gridless solar cells and solder ribbons are arranged according to a predetermined stringing rule to form a battery string to be cured and welded. The solder ribbons are laid on the solder ribbon laying path and intersect perpendicularly with each of the sub-grid lines on the surface of the corresponding gridless solar cells. The pre-arranged grid-less solar cells and solder ribbons are cured so that the solder ribbons are bonded to the corresponding grid-less solar cells by the adhesive. The solder ribbon bonded to the gridless cell with the adhesive is subjected to low-temperature heating to melt the solder on the solder ribbon, so that an alloyed connection is formed between the solder ribbon and the sub-grid line to form a cell string; The battery string was subjected to appearance quality inspection and EL inspection after being heated at low temperature.

9. The method for stringing battery cells as described in claim 8, characterized in that: The predetermined string arrangement rule is as follows: the i-th gridless cell is stacked on the upper side of the latter half of the i-th group of solder strips, and the first half of the (i+1)-th group of solder strips is stacked on the upper surface of the i-th gridless cell, where i is any natural number greater than 0; or The predetermined string arrangement rule is as follows: the latter half of the i-th group of solder ribbons is stacked on the upper surface of the i-th gridless cell, and the first half of the i-th group of solder ribbons is stacked on the upper surface of the (i-1)-th gridless cell, where i is any natural number greater than 1 and less than N+1, and N is the total number of gridless cells in the battery string.

10. The method for stringing battery cells as described in claim 8, characterized in that, The adhesive is a UV-curable adhesive, and curing the adhesive includes: irradiating the adhesive with UV light to cure the adhesive; or The adhesive is a thermosetting adhesive, and curing the adhesive includes heating the adhesive to cure it.

11. The method for stringing battery cells as described in claim 8, characterized in that, The low-temperature heating temperature is below 200°C, and the heating time for the same group of welding strips is 2s to 20s.

12. The method for stringing battery cells as described in claim 8, characterized in that, After performing appearance quality inspection and EL inspection on the battery strings after low-temperature heating, the battery cell stringing method further includes: The qualified battery strings are sequentially arranged, busbars are stacked and laminated, and the heating temperature of the lamination is lower than the melting temperature of the solder on the solder strip.

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