Back contact battery piece, battery assembly and manufacturing method

Abstract

The invention relates to the technical field of solar cell modules, and provides a back contact cell piece, a cell module and a manufacturing method, and the back contact cell piece comprises a cell piece body; the positive pole fine grid lines and the negative pole fine grid lines are arranged on the same side of the battery piece body at intervals; the positive electrode widening connection areas are arranged on the positive electrode fine grid lines and are arranged at intervals along the length direction of the positive electrode fine grid lines; the negative electrode widening connection areas are arranged on the negative electrode fine grid lines and are arranged at intervals along the length direction of the negative electrode fine grid lines; and the end part connecting wires are arranged at the end parts of the two sides of the battery piece body and are respectively connected with the positive electrode widening connecting area and the negative electrode widening connecting area. By adopting the design of widening the connecting area of the fine grid, the welding area is increased, the problems of pseudo soldering, grid breakage and the like in the main-grid-free welding process are solved, the silver paste consumption of the main grid is reduced, the welding stability and the welding quality are improved, and the assembly reliability is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of solar cell modules, and in particular to a back contact solar cell sheet, a solar cell module and a manufacturing method thereof. Background Art

[0002] The positive and negative grid lines of the back-contact solar cell are both on the back of the cell, generally including fine grid lines and main grid lines that intersect the fine grid lines perpendicularly. At the same time, there are PAD points, which are contact points, on the main grid lines. The fine grid lines are mainly used to collect current, and the main grid lines converge the current collected by the secondary grid lines and conduct it through the welding strips connected to them. The PAD points enhance the welding effect between the welding strips and the solar cells.

[0003] Both the fine grid lines and the main grid lines are made of silver paste, which is relatively expensive. In order to reduce costs, the main grid lines and PAD points in the middle area of ​​the battery surface are removed to form a main grid-free back contact battery. The welding strip is in direct or indirect contact with the positive and negative fine grid lines on the back of the battery for welding.

[0004] However, for the back-contact battery without the main grid lines and PAD points, when the welding ribbon contacts and welds the positive and negative fine grid lines on the back of the battery, the welding contact area is small, which reduces the welding stability, affects the welding effect and the reliability of the battery assembly without main grid back contact. Summary of the invention

[0005] To solve the above problems, the present invention provides a back-contact battery cell, a battery module and a manufacturing method, which adopts a fine grid and widened connection area design to increase the welding area, solve the problems of cold solder joints and broken grids in the welding process without a main grid, and improve the welding stability and welding quality while reducing the main grid silver paste consumption, thereby improving the reliability of the module.

[0006] In a first aspect, the present disclosure provides a back-contact battery cell, comprising: a battery cell body; positive electrode fine grid lines and negative electrode fine grid lines, which are arranged at intervals on the same side of the battery cell body; a positive electrode widened connection area, which is arranged on the positive electrode fine grid lines and arranged at intervals along the length direction of the positive electrode fine grid lines; a negative electrode widened connection area, which is arranged on the negative electrode fine grid lines and arranged at intervals along the length direction of the negative electrode fine grid lines; and end connection lines, which are arranged at the ends of both sides of the battery cell body and are respectively connected to the positive electrode widened connection area and the negative electrode widened connection area.

[0007] In this way, by setting up the positive electrode widened connection area and the negative electrode widened connection area, the welding area is increased, so that the main grid lines and connection points in the middle area of ​​the battery cell surface are omitted, and only the end connection lines at the ends of the battery cell body are left, which solves the problems of cold soldering and broken grids in the main gridless welding process, and can also reduce the main grid silver paste consumption, so that most areas on the battery cell body can form a main gridless back contact battery, which helps to connect the welding strip to the positive electrode fine grid line and the negative electrode fine grid line respectively through the positive electrode widened connection area and the negative electrode widened connection area, thereby ensuring the stability of the welding strip connected to the battery cell body, thereby enhancing the welding effect of the battery cell body and the reliability of the main gridless design of the back contact battery.

[0008] In some embodiments, in the direction in which the positive electrode fine grid lines and the negative electrode fine grid lines are arranged at intervals, the positive electrode widened connection area and the negative electrode widened connection area are staggered.

[0009] This arrangement makes it easier to stagger the connection position between the positive electrode thin grid line and the welding strip and the connection position between the negative electrode thin grid line and the welding strip, which helps to connect the welding strip to the battery cell.

[0010] In some embodiments, a positive electrode insulation region is also provided on the positive electrode fine grid line, and a negative electrode insulation region is provided on the negative electrode fine grid line. In the extension direction of the positive electrode fine grid line and the negative electrode fine grid line, the positive electrode insulation region is located between two adjacent positive electrode widened connection regions, and the negative electrode insulation region is located between two adjacent negative electrode widened connection regions.

[0011] Such arrangement allows the plurality of positive electrode widened connection regions to be separated by the positive electrode insulation region and the negative electrode widened connection regions to be separated by the negative electrode insulation region in the extension direction of the positive electrode fine grid lines and the extension direction of the negative electrode fine grid lines.

[0012] In some embodiments, in the direction in which the positive electrode fine grid lines and the negative electrode fine grid lines are arranged at intervals, the positive electrode insulation region is located between two adjacent negative electrode widened connection regions, and the negative electrode insulation region is located between two adjacent positive electrode widened connection regions.

[0013] Such arrangement can separate the positive and negative fine grid lines in the direction in which the positive and negative fine grid lines are arranged at intervals, thereby preventing the positive and negative fine grid lines from being connected to the welding strip at the same time.

[0014] In some embodiments, the battery cell body includes a first sheet and a second sheet, the first sheet and the second sheet are symmetrically arranged, the positive electrode fine grid lines and the negative electrode fine grid lines on the first sheet and the positive electrode fine grid lines and the negative electrode fine grid lines on the second sheet are symmetrically arranged, and the positive electrode insulation area and the negative electrode insulation area on the first sheet and the positive electrode insulation area and the negative electrode insulation area on the second sheet are symmetrically arranged.

[0015] This arrangement can increase the printing efficiency of the battery cell body when manufacturing the battery cell body, and make the battery cell body have the same structure after being divided into two parts, which is helpful for interconnecting the battery cells without distinguishing between the first sheet and the second sheet.

[0016] In some embodiments, a solder paste layer is provided on the battery cell body and located on the positive electrode widened connection area and the negative electrode widened connection area.

[0017] This arrangement makes it easier to connect the battery cell body and the solder ribbon through the solder paste layer.

[0018] In some embodiments, the size of the solder paste layer is smaller than or equal to the size of the positive electrode widened connection area and the negative electrode widened connection area, and the height of the solder paste layer is greater than or equal to the height of the positive electrode insulation area and the negative electrode insulation area.

[0019] This arrangement ensures that the welding ribbon is in full contact with the battery cell when connected, while increasing the welding tension between the welding ribbon and the battery cell.

[0020] The second aspect of the present disclosure provides a back-contact battery assembly, comprising: a battery string, comprising a plurality of back-contact battery cells as described in the first aspect; a positive electrode welding strip, arranged on the positive electrode widened connection area of ​​the back-contact battery cell; a negative electrode welding strip, arranged on the negative electrode widened connection area of ​​the back-contact battery cell; and connecting glue points, arranged on the back-contact battery cell, for connecting the back-contact battery cell to the positive electrode welding strip and the negative electrode welding strip, respectively.

[0021] In this way, by setting connecting glue points, multiple stacked battery cells can be connected through positive electrode welding strips and negative electrode welding strips to form a battery string, and the connection stability of the formed battery string is ensured under the connection of the connecting glue points, which helps to reduce the risk of welding strip deviation and improve production yield.

[0022] In some embodiments, the positive electrode insulation region and the negative electrode insulation region of the back contact battery cell are recessed toward the battery cell body to form connection grooves for the connection glue dots to be inserted.

[0023] Such a configuration is beneficial to reduce the deviation of the soldering ribbon when it is connected to the battery cell, ensure the firmness and reliability of the glue point bonding, and help to weld multiple battery cells to form a battery string after the soldering ribbon is connected to the connecting glue point.

[0024] The third aspect of the present disclosure provides a method for manufacturing a back-contact battery assembly, comprising: printing positive electrode fine grid lines, negative electrode fine grid lines and end connection lines on the battery cell body to form a positive electrode widened connection area, a negative electrode widened connection area, a positive electrode insulation area and a negative electrode insulation area; printing a solder paste layer on the positive electrode widened connection area and the negative electrode widened connection area; dicing the battery cell body to form the same first and second sheets; connecting a plurality of the first sheets and the second sheets through welding strips to form a battery string.

[0025] With such arrangement, on the one hand, the main grid in most areas of the battery cell is replaced by the formed widened positive electrode connection area and the widened negative electrode connection area, which increases the welding area while reducing the main grid silver paste consumption, and also improves the welding stability and welding quality, thereby improving the reliability of the back contact battery assembly; on the other hand, by forming a symmetrical first sheet and a second sheet, it helps to avoid distinguishing between the first sheet and the second sheet during the battery string manufacturing process, and there is no need to rotate half the sheet, thereby improving the convenience of back contact battery assembly production.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The busbar-free back contact battery adopts a thin grid widened connection area design, which increases the welding area and solves the problems of cold welding and broken grid in the busbar-free welding process. It reduces the consumption of busbar silver paste and improves the welding stability and welding quality, thereby improving the reliability of the module. At the same time, the central symmetrical electrode design in the whole cell makes the electrode distribution of the two halves of the cell after dicing exactly the same. In the process of making the cell string, there is no need to distinguish between the first and second sheets, and there is no need to rotate the half sheet, which improves the convenience of module production.

[0028] 2. The use of low-temperature welding reduces the post-welding warping of the busbar-free back-contact battery. The use of connecting glue to fix the soldering ribbon reduces the risk of soldering ribbon deviation and improves the production yield. At the same time, the mechanical connection force provided by the connecting glue improves the adhesion between the soldering ribbon and the battery cell, further improving the reliability of the busbar-free back-contact battery module.

[0029] Other features and advantages of the present disclosure will be described in the following description, and partly become apparent from the description, or be understood by implementing the present disclosure. The purpose and other advantages of the present disclosure can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A schematic diagram of the back structure of a back-contact battery cell provided in an embodiment of the present disclosure;

[0032] Figure 2 A schematic diagram of the structure of a half-cell back-contact battery cell provided in an embodiment of the present disclosure;

[0033] Figure 3 An enlarged view of the positive electrode widened connection area and the negative electrode widened connection area provided in an embodiment of the present disclosure;

[0034] Figure 4 A schematic diagram of a half-cell back-contact battery structure provided in an embodiment of the present disclosure;

[0035] Figure 5 A schematic diagram of a battery string structure provided in an embodiment of the present disclosure;

[0036] Figure 6 An enlarged schematic diagram of a connection glue point provided in an embodiment of the present disclosure;

[0037] Figure 7 A schematic diagram of the structure of the welding ribbon provided in the embodiment of the present disclosure connected to the battery cell;

[0038] Figure 8 An enlarged schematic diagram of the connection between the connecting glue point and the welding ribbon provided in the embodiment of the present disclosure;

[0039] Fig. 9 A flow chart of a method for manufacturing a back-contact battery assembly provided in an embodiment of the present disclosure;

[0040] Fig.10 A flow chart of the method for glue connection provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0042] See also Figure 1 and Figure 2 , Figure 1 A schematic diagram of the back structure of a back-contact battery cell provided in an embodiment of the present disclosure is shown. Figure 2 1 is a schematic diagram of the structure of a half-cell back-contact battery cell provided by an embodiment of the present disclosure. A back-contact battery cell includes a battery cell body 10, positive electrode fine grid lines 11, negative electrode fine grid lines 12, positive electrode insulation area 13, negative electrode insulation area 14, and end connection lines 15. A plurality of positive electrode fine grid lines 11 and negative electrode fine grid lines 12 are arranged at intervals on the same side of the battery cell body 10 and on the back side of the battery cell body 10; the end connection lines 15 are arranged at the ends of both sides of the battery cell body 10.

[0043] In this embodiment, the positive electrode fine grid line 11 and the negative electrode fine grid line 12 are arranged along Figure 1 The positive electrode fine grid lines 11 and the negative electrode fine grid lines 12 are alternately spaced and arranged in parallel in the X direction. Figure 1 The end connection line 15 is located at the two end areas of the back of the battery cell body 10 and is connected to the positive electrode fine grid line 11 and the negative electrode fine grid line 12. The length of the end connection line 15 is 5 to 20 mm. The end connection line 15 can be a straight main grid line or a forked main grid line. The end connection line 15 is set to ensure the collection effect of the edge current of the battery end.

[0044] It should be noted that the end connection line 15 is only located at the end edge of the battery cell body 10 .

[0045] In some embodiments, see Figure 2 and Figure 3 , Figure 3 An enlarged view of the positive electrode widened connection area and the negative electrode widened connection area provided in an embodiment of the present disclosure, wherein the positive electrode widened connection area 111 is arranged on the positive electrode fine grid line 11, and is arranged at intervals along the length direction of the positive electrode fine grid line 11; the negative electrode widened connection area 121 is arranged on the negative electrode fine grid line 12, and is arranged at intervals along the length direction of the negative electrode fine grid line 12; and the end connection lines 15 are respectively connected to the positive electrode widened connection area 111 and the negative electrode widened connection area 121.

[0046] Exemplarily, in the direction in which the positive electrode thin gate lines 11 and the negative electrode thin gate lines 12 are arranged in an alternate manner, the positive electrode widened connection area 111 and the negative electrode widened connection area 121 are staggered.

[0047] It can be understood that a plurality of positive electrode widened connection regions 111 are respectively provided along the X direction and the Y direction, and a plurality of negative electrode widened connection regions 121 are respectively provided along the X direction and the Y direction.

[0048] For example, the minimum number of the positive electrode widening connection area 111 and the negative electrode widening connection area 121 in the same X direction is 2, and they are located at both ends of the half-cell structure of the battery cell body 10, such as Figure 2The maximum number of positive electrode widened connection areas 111 and negative electrode widened connection areas 121 in the same X direction is equal to the number of positive electrode fine grid lines 11 and negative electrode fine grid lines 12 covered by them, that is, each positive electrode fine grid line 11 and negative electrode fine grid line 12 without an insulating area is provided with a widened connection area (such as Figure 1 shown).

[0049] For another example, the positive electrode widened connection area 111 can be rectangular or rhombus-shaped. If it is a rectangle, the length of the rectangle (Y direction) is 0.4-2.0 mm, and the width (X direction) is 0.05-0.15 mm; if it is a rhombus, the length of the long diagonal line of the rhombus (Y direction) is 0.4-2.0 mm, and the length of the short diagonal line (X direction) is 0.05-0.15 mm.

[0050] For another example, the negative electrode widened connection area 121 can be rectangular or rhombus-shaped. If it is a rectangle, the length of the rectangle (Y direction) is 0.4-2.0 mm, and the width (X direction) is 0.03-0.1 mm; if it is a rhombus, the length of the long diagonal line of the rhombus (Y direction) is 0.4-2.0 mm, and the length of the short diagonal line (X direction) is 0.03-0.1 mm.

[0051] It should be noted that the positive electrode widened connection area 111 and the negative electrode widened connection area 121 may also be other shapes that can increase the contact area, such as a circle or an ellipse.

[0052] In some embodiments, continue to refer to Figure 2 and Figure 3 , multiple positive electrode insulation regions 13 are arranged on the positive electrode fine grid lines 11, and multiple negative electrode insulation regions 14 are arranged on the negative electrode fine grid lines 12. In the extension direction of the positive electrode fine grid lines 11 and the negative electrode fine grid lines 12, the positive electrode insulation region 13 is located between two adjacent positive electrode widening connection regions 111, and the negative electrode insulation region 14 is located between two adjacent negative electrode widening connection regions 121. The positive electrode insulation region 13 and the negative electrode insulation region 14 are arranged in the contact area between the battery cell body 10 and the welding strip.

[0053] It can be understood that the positive electrode insulation region 13 is provided in multiples along the X direction and the second direction Y, and is arranged in sequence. The negative electrode insulation region 14 is provided in multiples along the X direction and the Y direction, and is arranged in sequence. The positive electrode widening connection region 111 is alternately arranged with the positive electrode insulation region 14 in the Y direction, and is alternately arranged with the negative electrode insulation region 13 in the X direction. The negative electrode widening connection region 121 is alternately arranged with the negative electrode insulation region 13 in the Y direction, and is alternately arranged with the positive electrode insulation region in the X direction.

[0054] That is, in the direction in which the positive electrode fine grid lines 11 and the negative electrode fine grid lines 12 are arranged at intervals, the positive electrode insulation region 13 is located between two adjacent negative electrode widened connection regions 121 , and the negative electrode insulation region 14 is located between two adjacent positive electrode widened connection regions 111 .

[0055] In some embodiments, the battery cell body includes a first sheet A and a second sheet B, the first sheet A and the second sheet B are symmetrically arranged, the positive electrode fine grid lines 11 and the negative electrode fine grid lines 12 of the first sheet A and the positive electrode fine grid lines 11 and the negative electrode fine grid lines 12 of the second sheet B are symmetrically arranged, the positive electrode insulation area 13 and the negative electrode insulation area 14 of the first sheet A and the positive electrode insulation area 13 and the negative electrode insulation area 14 on the second sheet B are symmetrically arranged.

[0056] Exemplarily, the positive electrode insulation area 13 in the first sheet A and the positive electrode insulation area 13 in the second sheet B are distributed in a centrally symmetrical manner, and the negative electrode insulation area 14 in the first sheet A and the negative electrode insulation area 14 in the second sheet B are distributed in a centrally symmetrical manner, thereby forming centrally symmetrical positive and negative electrodes in the two half-sheet structures of the battery cell body 10, so that the first sheet A and the second sheet B have the same structure after dicing, and there is no need to distinguish between the first sheet A and the second sheet B when interconnecting at the component end, and there is no need to rotate 180°, which facilitates interconnection and series connection.

[0057] In some embodiments, a solder paste layer is provided on the battery cell body 10 and is located on the positive electrode widening connection area 111 and the negative electrode widening connection area 121. It can be understood that the solder paste layer covers the positive electrode widening connection area 111 and the negative electrode widening connection area 121. The solder paste layer may be rectangular, diamond or circular. The size of the solder paste layer is less than or equal to the size of the positive electrode widening connection area 111 and the negative electrode widening connection area 121, and the height of the solder paste layer is greater than or equal to the height of the positive electrode insulation area 13 and the negative electrode insulation area 14.

[0058] In this embodiment, a positive electrode solder paste layer 112 and a negative electrode solder paste layer 122 are respectively provided on the positive electrode fine grid 11 and the negative electrode fine grid 12. The solder paste layer is a low-temperature solder paste of tin-bismuth or tin-bismuth-lead or tin-bismuth-silver, and the solder paste has a melting point between 130 and 160° C. and is used for welding and connecting with the solder strip.

[0059] Based on the above back contact battery sheet, the embodiment of the present disclosure also provides a back contact battery assembly corresponding to the above back contact battery sheet, the stacked structure from top to bottom is a front cover plate, a front packaging film, a battery string 20 formed by connecting a plurality of half sheets of the above back contact battery sheet body 10, a back packaging film, and a back cover plate. Figure 4 and Figure 5 , Figure 4 A schematic diagram of a half-cell back-contact battery structure provided in an embodiment of the present disclosure, Figure 5 The back contact battery assembly includes a battery string 20, a connection glue point 23 (Ultraviolet Curing, UV), a positive electrode welding strip 21 and a negative electrode welding strip 22.

[0060] The battery string 20 includes a plurality of the above-mentioned back-contact battery cell bodies 10; the connecting glue points 23 are arranged on the positive electrode insulation area 13 and the negative electrode insulation area 14 of the back-contact battery cell body 10; the positive electrode welding strip 22 is arranged on the connecting glue points 23 and the positive electrode widened connection area 111 of the back-contact battery cell body 10; the negative electrode welding strip 21 is arranged on the connecting glue points 23 and the negative electrode widened connection area 121 of the back-contact battery cell body 10.

[0061] In this embodiment, see Figure 5 and Figure 6 , Figure 6 This is an enlarged schematic diagram of the connection glue points provided in the embodiment of the present disclosure, wherein the negative electrode welding strip 21 is arranged on the positive electrode insulation area 13 and the negative electrode widened connection area 121 on the back side of the back contact battery cell body 10, and the positive electrode welding strip 22 is arranged on the negative electrode insulation area 14 and the positive electrode widened connection area 111 on the back side of the back contact battery cell body 10, and the positive electrode welding strip 22 and the negative electrode welding strip 21 are arranged in a forked finger shape.

[0062] It should be noted that the UV glue for connecting the glue points can also be other glues, such as thermosetting glue. The negative electrode welding strip 21 and the positive electrode welding strip 22 (one connected to the positive electrode and the other connected to the negative electrode) are low-temperature alloy coating welding strips, and the melting point of the coating is between 130 and 160°C to achieve low-temperature welding and reduce the welding stress and post-welding warping of the back contact battery cell body 10.

[0063] In some embodiments, participation Figure 5 and Figure 6 The connecting glue points 23 are arranged on the positive electrode insulation area 13 and the negative electrode insulation area 14 of the back contact battery cell body 10, below the welding strip and above the battery cell.

[0064] For example, the minimum number of connecting glue points 23 in each column in the X direction is at least three, and they are located at both ends and the middle of the negative electrode welding strip 21 and the positive electrode welding strip 22; the maximum number of connecting glue points 23 is the same as the number of positive electrode insulation areas 13 and negative electrode insulation areas 14.

[0065] For example, the area of ​​the connecting glue point 23 is not less than 0.2 m2 and the height is not less than 0.02 mm to ensure the fixing effect and bonding strength of the connecting glue on the welding strip.

[0066] In some embodiments, the positive electrode insulation area 13 and the negative electrode insulation area 14 of the back contact battery cell body 10 are recessed toward the battery cell body 10 to form a connection groove for the connection glue point 23 to be inserted, which helps to reduce the thickness occupied by the connection glue point 23 on the battery cell body 10 after the connection glue point 23 is inserted, so as to reduce the deviation of the welding ribbon when the welding ribbon is connected to the battery cell body 10, and improve the firmness and reliability of the bonding of the connection glue point 23, thereby facilitating the welding of multiple battery cells to form a battery string 20 after the welding ribbon is connected to the connection glue point 23.

[0067] In some embodiments, reference Figure 7 and Figure 8 , Figure 7 This is a schematic diagram of the structure of the welding ribbon provided in the embodiment of the present disclosure connected to the battery cell. Figure 8 This is an enlarged schematic diagram of the connection between the connecting glue point and the welding ribbon provided in the embodiment of the present disclosure. The negative electrode welding ribbon 21 and the positive electrode welding ribbon 22 in the battery string 20 have been welded to the positive electrode widened connection area 111, the negative electrode widened connection area 121 and the solder paste layer of the battery cell 10 to form an ohmic contact. The connecting glue point 23 is provided on the non-contact surface between the positive electrode welding ribbon 22 and the negative electrode welding ribbon 21 and the battery cell body 10, and contacts the battery cell body 10 at the same time to bond the negative electrode welding ribbon 21 and the positive electrode welding ribbon 22 to the battery cell body 10. The function of the connecting glue point 23 is to provide a mechanical connection force between the welding ribbon and the battery cell body 10, further strengthen the adhesion between the welding ribbon and the main grid-free back contact battery cell body 10, and improve the reliability of the back contact battery assembly.

[0068] In some other embodiments, the negative electrode welding strip 21, the positive electrode welding strip 22 in the battery string 20 and the battery cell body 10 are only bonded by the connecting glue point 23 to form the battery string, and the positive electrode welding strip, the negative electrode welding strip in the battery string 20 and the positive electrode widened connection area 111, the negative electrode widened connection area 121 and the solder paste layer of the battery cell body 10 do not form an ohmic contact, and the welding strip and the battery cell body 10 are alloyed and connected in the subsequent lamination process to form an ohmic contact. The function of the connecting glue point is to bond and pre-fix the welding strip to multiple battery cells to form the battery string 20.

[0069] Based on the same inventive concept as the above disclosure, the present disclosure also provides a method for manufacturing a back-contact battery assembly. Fig. 9 , Fig. 9 A flow chart of a method for manufacturing a back contact battery assembly provided in an embodiment of the present disclosure, the method comprising the following steps:

[0070] S100, printing positive electrode fine grid lines, negative electrode fine grid lines and end connection lines on the battery cell body to form a positive electrode widened connection area, a negative electrode widened connection area, a positive electrode insulation area and a negative electrode insulation area.

[0071] In this embodiment, a number of busbar-free back contact cell bodies 10 are prepared, and the positive electrode fine grid lines 11 and the negative electrode fine grid lines 12 are first screen-printed on the cell body 10. The positive electrode widening connection area 111 and the negative electrode widening connection area 121 in the back contact cell body 10 can be printed simultaneously with the positive electrode fine grid 11 and the negative electrode fine grid 12 by one screen printing to form a busbar-free design in most areas of the cell body 10; the positive electrode fine grid 11 and the negative electrode fine grid 12 can also be printed first, and the printing of the positive electrode widening connection area 111 and the negative electrode widening connection area 121 can be completed by a second printing. The preparation of the busbar-free back contact cell body 10 also includes the printing of the positive electrode insulation area 13, the negative electrode insulation area 14 and the end connection line 15. In the two half-sheet structures of the prepared busbar-free back contact cell body 10, the positive electrodes are centrally symmetrically distributed, and the negative electrodes are centrally symmetrically distributed.

[0072] S200, printing a solder paste layer on the positive electrode widened connection area and the negative electrode widened connection area.

[0073] In this embodiment, the solder paste layer is printed and dried on the busbar-free back contact cell body 10 , and the printing height of the solder paste layer is not less than the printing height of the positive electrode insulation area 13 and the negative electrode insulation area 14 .

[0074] S300, dicing the battery cell body to form a first sheet and a second sheet that are identical.

[0075] In this embodiment, the busbar-free back contact cell body 10 is diced to obtain two half-cell cells, namely a first cell body A and a second cell body B. The two half-cell cells after dicing are completely identical.

[0076] S400, connecting a plurality of first sheets and second sheets through welding strips to form a battery string.

[0077] In this embodiment, see Fig.10 , Fig.10 The method flow chart of the glue dispensing connection provided by the embodiment of the present disclosure, step S400 may also include the following steps:

[0078] S401, applying UV connection glue to the positive electrode insulation area and the negative electrode insulation area of ​​the first sheet, and the positive electrode insulation area and the negative electrode insulation area of ​​the second sheet.

[0079] In this embodiment, the UV connecting glue dots 23 are arranged on the positive electrode insulation area 13 and the negative electrode insulation area 14 of the main grid-free back contact battery cell body 10, and are located below the welding strip. The application of UV connecting glue can be completed by steel screen printing, dispensing, spraying, etc.

[0080] S402, transporting a plurality of first sheets and second sheets to which UV connection glue has been applied to a designated location.

[0081] S403, cutting and laying the welding tape on the first sheet and the second sheet.

[0082] In this embodiment, the cut negative electrode welding strips 21 and positive electrode welding strips 22 are transported to the designated positions on the back of the first sheet and the second sheet to which glue has been applied, and are fixed by using a tool for pressing.

[0083] S404, curing the UV connection glue point 23 by irradiation with a UV lamp to pre-fix the soldering tape to the first sheet and the second sheet.

[0084] S405 , welding the solder strip to the solder paste layers of the first sheet and the second sheet to form an electrical connection.

[0085] In this embodiment, the negative electrode welding strip 21 and the positive electrode welding strip 22 are respectively welded to the negative electrode fine grid 12, the positive electrode fine grid 11, the negative electrode widened connection area 121, and the positive electrode widened connection area 111 on the battery cell body 10 to form an ohmic contact. The welding adopts low-temperature welding, and the welding temperature is not higher than 180°C. Low-temperature welding effectively reduces the thermal stress of the battery and reduces the warping of the battery. The welding method can adopt infrared heating, thermal contact, etc.

[0086] In some embodiments, the welding step may be selected not to be performed. After the UV connecting glue point 23 is cured in step S404, the tooling is removed, and only steps S401, S402, S403, and S404 are repeated to connect multiple half-cell battery cells 10 without main grid back contact by bonding the welding ribbons with the UV connecting glue point 23 to form a battery string, and the welding is completed in the subsequent lamination process to form an ohmic contact.

[0087] In some embodiments, a welding step can be selected: the welding step can be performed after the curing step, and the tooling is removed after the welding is completed, and steps S401, S402, S403, S404, and S405 are repeated to complete the battery string production. The resulting battery string welding tape has formed an ohmic contact with the battery, and the welding quality can be tested by EL testing; another welding step can also be selected: the welding step can be performed before the UV connecting glue curing step, and the tooling is removed after the UV connecting glue is cured, and steps S401, S402, S403, S405, and S404 are repeated to complete the battery string production.

[0088] In some embodiments, it is optional to apply glue and cure the UV connecting glue after welding is completed. The UV connecting glue point 23 is arranged on the non-contact surface between the welding strip and the battery cell body 10 and contacts the battery cell body 10 at the same time, so as to bond the negative electrode welding strip 21 and the positive electrode welding strip 22 to the battery cell body 10, further strengthen the adhesion between the welding strip and the main grid back contactless battery cell body 10, and improve the reliability of the main grid back contactless battery assembly.

[0089] It should be noted that in the process of manufacturing the above-mentioned battery string, the spacing between the two adjacent half-cell batteries is a small spacing of 0.3 to 1.2 mm. The spacing between the two adjacent half-cell batteries is a negative spacing of -0.3 to -1.0 mm. Since the positive and negative poles of the main grid-free back contact battery are connected on the back, negative spacing stack welding can be directly performed to increase the component packaging density, thereby improving the component efficiency.

[0090] S500, stacking battery strings.

[0091] In this embodiment, the back cover plate, the back packaging film, a plurality of battery strings 20, the front packaging film, and the front cover plate are stacked in order from bottom to top, wherein the plurality of battery strings are connected according to a certain circuit layout.

[0092] S600 , laminating the back contact battery assembly.

[0093] In this embodiment, the above laminated parts are laminated to obtain a busbar-free back contact battery laminate. If the battery string 20 in the laminate is a battery string that has not undergone the above S405 welding step, but only the S401, S402, S403, and S404 steps, then the welding step is completed during the lamination process. For this type of battery string, the back packaging film used has low fluidity on the contact surface side of the battery during lamination to ensure a good welding effect. The frame and junction box are subsequently installed to form a busbar-free back contact battery assembly.

[0094] Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A back contact battery cell, characterized in that: include: Battery cell body; The positive electrode fine grid lines and the negative electrode fine grid lines are arranged at intervals on the same side of the battery cell body; A positive electrode widening connection area is provided on the positive electrode fine grid line and is arranged at intervals along the length direction of the positive electrode fine grid line; The negative electrode widening connection area is arranged on the negative electrode fine grid line and is arranged at intervals along the length direction of the negative electrode fine grid line; The end connection lines are arranged at the ends of both sides of the battery sheet body and are respectively connected to the positive electrode widened connection area and the negative electrode widened connection area.

2. The back contact cell according to claim 1, characterized in that: In the direction in which the positive electrode fine grid lines and the negative electrode fine grid lines are arranged at intervals, the positive electrode widened connection area and the negative electrode widened connection area are staggered.

3. The back contact cell according to claim 1, characterized in that: A positive electrode insulation region is also provided on the positive electrode fine grid line, and a negative electrode insulation region is provided on the negative electrode fine grid line. In the extension direction of the positive electrode fine grid line and the negative electrode fine grid line, the positive electrode insulation region is located between two adjacent positive electrode widened connection regions, and the negative electrode insulation region is located between two adjacent negative electrode widened connection regions.

4. The back contact cell according to claim 3, characterized in that: In the direction in which the positive electrode fine grid lines and the negative electrode fine grid lines are arranged at intervals, the positive electrode insulation region is located between two adjacent negative electrode widened connection regions, and the negative electrode insulation region is located between two adjacent positive electrode widened connection regions.

5. The back contact cell according to claim 1, characterized in that: The battery cell body includes a first sheet and a second sheet, the first sheet and the second sheet are symmetrically arranged, the positive electrode fine grid lines and the negative electrode fine grid lines on the first sheet and the positive electrode fine grid lines and the negative electrode fine grid lines on the second sheet are symmetrically arranged respectively, and the positive electrode insulation area and the negative electrode insulation area on the first sheet and the positive electrode insulation area and the negative electrode insulation area on the second sheet are symmetrically arranged respectively.

6. The back contact cell according to claim 3, characterized in that: The battery cell body is provided with a solder paste layer located on the positive electrode widened connection area and the negative electrode widened connection area.

7. The back contact cell according to claim 6, characterized in that: The size of the solder paste layer is smaller than or equal to the size of the positive electrode widened connection area and the negative electrode widened connection area, and the height of the solder paste layer is greater than or equal to the height of the positive electrode insulation area and the negative electrode insulation area.

8. A back contact battery assembly, characterized in that: include: A battery string comprising a plurality of back-contact battery sheets according to any one of claims 1 to 7; A positive electrode welding strip, arranged on the positive electrode widened connection area of ​​the back contact battery sheet; A negative electrode welding strip is arranged on the negative electrode widened connection area of ​​the back contact battery sheet; The connecting glue points are arranged on the back contact battery sheet and are used to connect the back contact battery sheet to the positive electrode welding strip and the negative electrode welding strip respectively.

9. The back contact battery assembly according to claim 8, characterized in that: The positive electrode insulation area and the negative electrode insulation area of ​​the back contact battery sheet are recessed toward the battery sheet body to form connection grooves for the connection glue dots to be inserted.

10. A method for manufacturing a back contact battery assembly, characterized in that: include: Printing positive electrode fine grid lines, negative electrode fine grid lines and end connection lines on the battery cell body to form a positive electrode widened connection area, a negative electrode widened connection area, a positive electrode insulation area and a negative electrode insulation area; Printing a solder paste layer on the positive electrode widened connection area and the negative electrode widened connection area; Slicing the battery cell body to form a first sheet and a second sheet that are identical; A plurality of the first sheets and the second sheets are connected by welding strips to form a battery string.

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