Back contact cell assembly with no busbars and method of manufacturing the same

Abstract

The application is suitable for the technical field of solar cells, and provides a main-grid-free back contact cell module and a preparation method thereof. In the main-grid-free back contact cell module, a main-grid-free back contact cell string is composed of main-grid-free back contact cells. The positive and negative welding ribbons are fixed on the main-grid-free back contact cells by a pre-fixing film. In this way, the back surface of the main-grid-free back contact cell does not need to be provided with a main grid line, and does not need to be printed with a solder pad, so that the use of silver paste can be reduced, and the cost can be reduced. Meanwhile, after the positive and negative welding ribbons are laid, the positive and negative welding ribbons are fixed on the back surface of the main-grid-free back contact cell by using the pre-fixing film. The flowability of the pre-fixing film in the initial laminating process is lower than that of the second adhesive film in the initial laminating process, so that the positive and negative welding ribbons can be effectively prevented from being deviated in the process of manufacturing the module, and the positioning and alignment accuracy of the positive and negative welding ribbons can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to a busbar-free back-contact solar cell assembly and a preparation method thereof. Background Art

[0002] At present, the majority of back-contact photovoltaic modules in the photovoltaic industry are MBB, which adopts high-temperature infrared welding. That is, the solder pads are printed on the main grid of the battery cell, the solder paste is printed on the solder pads, and the insulating glue is printed on the fine grid lines of opposite polarity near the main grid. The printed solder paste and insulating glue are dried or cured. The processed battery cells are arranged into a string, and the solder ribbon is covered on the top of the main grid line, which is pressed and then infrared welded.

[0003] However, in such a technical solution, the battery cell needs to use more silver paste in the process of making the main grid and welding pad, which is very expensive. At the same time, due to the presence of solder paste when placing the welding ribbon, the placement of the welding ribbon will easily cause yield problems such as welding ribbon offset. Summary of the Invention

[0004] The present application provides a main grid-free back contact battery assembly and a preparation method thereof, aiming to solve the technical problems in the prior art of low yield, high cost and easy deviation of welding strips in the process of manufacturing battery assemblies.

[0005] The present application is implemented as follows: a busbar-less back-contact battery assembly according to an embodiment of the present application includes a first cover plate, a first adhesive film, at least one busbar-less battery string, a second adhesive film, and a second cover plate stacked in sequence, wherein the busbar-less battery string includes:

[0006] A plurality of busbar-less back-contact batteries, wherein the back of the busbar-less back-contact batteries has a plurality of positive electrode fine grids and a plurality of negative electrode fine grids, and the plurality of positive electrode fine grids and the plurality of negative electrode fine grids are alternately arranged in sequence;

[0007] A plurality of positive electrode welding strips and a plurality of negative electrode welding strips, wherein the positive electrode welding strips are arranged to cross the positive electrode fine grid and are conductively connected to the positive electrode fine grid, and the negative electrode welding strips are arranged to cross the negative electrode fine grid and are conductively connected to the negative electrode fine grid; and

[0008] A pre-fixed film layer, the pre-fixed film layer being disposed on the positive electrode welding strip and the negative electrode welding strip, the pre-fixed film layer being fixedly connected to the back surface to fix the positive electrode welding strip and the negative electrode welding strip on the back surface;

[0009] The second adhesive film is covered on the pre-fixed film layer, and the fluidity of the pre-fixed film layer during the initial lamination process is lower than the fluidity of the second adhesive film during the initial lamination process.

[0010] Furthermore, the pre-fixed film layer has a gram weight of 50g-200g per square meter.

[0011] Furthermore, a first welding layer is provided on the positive electrode fine grid at a position in contact with the positive electrode welding strip, and the positive electrode welding strip is connected to the first welding layer; a second welding layer is provided on the negative electrode fine grid at a position in contact with the negative electrode welding strip, and the negative electrode welding strip is connected to the second welding layer.

[0012] Furthermore, the first soldering layer and the second soldering layer are solder paste.

[0013] Furthermore, the positive electrode welding strip completely covers the first welding layer, and the negative electrode welding strip completely covers the second welding layer.

[0014] Furthermore, a first insulating layer is provided on the positive electrode thin grid at a position where the positive electrode thin grid intersects with the negative electrode welding strip, and the negative electrode welding strip is insulated and isolated from the positive electrode thin grid by the first insulating layer;

[0015] A second insulating layer is provided on the negative electrode fine grid at a position where the negative electrode fine grid intersects with the positive electrode welding strip, and the positive electrode welding strip is insulated and isolated from the positive electrode fine grid by the second insulating layer.

[0016] Furthermore, the positive electrode thin grid is broken at a position where it intersects with the negative electrode welding strip, and the negative electrode thin grid is broken at a position where it intersects with the positive electrode welding strip.

[0017] Furthermore, the pre-fixed film layer includes at least one of PVB film, EVA film, EPE film, EP film and POE film, and the second film includes at least one of POE film, EVA film, EPE film, EP film, PE film and PVB film.

[0018] Furthermore, two adjacent busbar-free back contact batteries are arranged at intervals;

[0019] Wherein, the pre-fixed film layer covers the busbar-less back contact cell; or

[0020] The pre-fixed film layer simultaneously covers the busbar-free back contact cell and the gap between two adjacent busbar-free back contact cells; or

[0021] The pre-fixed film layer at least covers the positive electrode welding strip and the negative electrode welding strip.

[0022] Furthermore, the plurality of positive electrode welding strips include a plurality of first positive electrode welding strips and a plurality of second positive electrode welding strips, the pre-fixed film layer is arranged on the first positive electrode welding strip to fix the first positive electrode welding strip on the back side, and the second positive electrode welding strip is fixed on the back side by dispensing glue.

[0023] Furthermore, the plurality of negative electrode welding strips include a first negative electrode welding strip and a second negative electrode welding strip, the pre-fixed film layer is arranged on the first negative electrode welding strip to fix the first negative electrode welding strip on the back side, and the second negative electrode welding strip is fixed on the back side by dispensing glue.

[0024] The present application also provides a method for preparing a busbar-free back-contact battery assembly, the method comprising:

[0025] A plurality of busbar-free back-contact batteries are provided; the back of the busbar-free back-contact batteries has a plurality of positive electrode fine grids and a plurality of negative electrode fine grids, and the plurality of positive electrode fine grids and the plurality of negative electrode fine grids are alternately arranged in sequence;

[0026] Laying a plurality of positive electrode welding strips and a plurality of negative electrode welding strips on the busbar-less back contact battery; wherein the positive electrode welding strips are arranged crosswise with the positive electrode thin grid and are conductively connected to the positive electrode thin grid, and the negative electrode welding strips are arranged crosswise with the negative electrode thin grid and are conductively connected to the negative electrode thin grid;

[0027] Laying a pre-fixed film layer on the plurality of busbar-less back-contact cells, and slightly melting and then solidifying the pre-fixed film layer to adhere to the back surface of the busbar-less back-contact cells, thereby fixing the positive electrode welding ribbon and the negative electrode welding ribbon, thereby forming a busbar-less cell string;

[0028] Laying the busbar-less battery string on a first cover plate with a first adhesive film placed thereon, with the back surface of the busbar-less back-contact battery facing away from the first adhesive film;

[0029] Laying a second adhesive film and a second cover plate on the back side of the busbar-free back contact battery string;

[0030] Lamination and welding processing is performed to form a main grid-free back contact battery assembly; wherein the fluidity of the pre-fixed film layer during the initial lamination process is lower than the fluidity of the pre-fixed film layer during the initial lamination process.

[0031] Furthermore, the step of laying a pre-fixed film layer on the plurality of the busbar-less back contact cells and slightly melting the pre-fixed film layer to adhere to the back surface of the busbar-less back contact cells, thereby fixing the positive electrode welding ribbon and the negative electrode welding ribbon, comprises:

[0032] The pre-fixed film layer is adsorbed by an adsorption pressing block, and the pre-fixed film layer is placed on the main grid-free back contact battery and heated. During the heating process, pressure is applied to the pre-fixed film layer by the adsorption pressing block, so that the pre-fixed film layer is slightly melted and then solidified to adhere to the back side, thereby fixing the positive electrode welding strip and the negative electrode welding strip.

[0033] Furthermore, when laying the pre-fixed film layer, the temperature is maintained in the range of 50° C. to 150° C., so that the pre-fixed film layer is slightly melted and then solidified to be bonded to the back surface of the busbar-free back contact solar cell.

[0034] Furthermore, before the step of laying a plurality of positive electrode welding strips and a plurality of negative electrode welding strips on the busbar-less back contact battery, the preparation method further comprises:

[0035] Preparing a first welding layer at a position on the positive electrode fine grid that contacts the positive electrode welding strip, and preparing a second welding layer at a position on the negative electrode fine grid that contacts the negative electrode welding strip;

[0036] The step of laying a plurality of positive electrode welding strips and a plurality of negative electrode welding strips on the busbar-free back contact battery comprises:

[0037] A positive electrode welding tape is laid at the position of the first welding layer, and a negative electrode welding tape is laid at the position of the second welding layer.

[0038] Furthermore, the first soldering layer and the second soldering layer are both formed by printing solder paste and then drying and curing it, or by not drying and curing it.

[0039] Furthermore, before the step of laying a plurality of positive electrode welding strips and a plurality of negative electrode welding strips on the busbar-less back contact battery, the preparation method further comprises:

[0040] A first insulating layer is prepared on the positive electrode fine grid at a position where it intersects with the negative electrode welding strip, and a second insulating layer is prepared on the negative electrode fine grid at a position where it intersects with the positive electrode welding strip.

[0041] The present application also provides another method for preparing a busbar-free back contact battery assembly, the method comprising:

[0042] Laying a first adhesive film on the first cover plate;

[0043] Laying a plurality of busbar-free back contact cells arranged at intervals on the first adhesive film; the back of the busbar-free back contact cells has a plurality of positive electrode fine grids and a plurality of negative electrode fine grids, the plurality of positive electrode fine grids and the plurality of negative electrode fine grids are alternately arranged at intervals in sequence, and the back of the busbar-free back contact cells faces away from the first adhesive film;

[0044] Laying a plurality of positive electrode welding strips and a plurality of negative electrode welding strips on the busbar-less back contact battery; wherein the positive electrode welding strips are arranged crosswise with the positive electrode thin grid and are conductively connected to the positive electrode thin grid, and the negative electrode welding strips are arranged crosswise with the negative electrode thin grid and are conductively connected to the negative electrode thin grid;

[0045] Laying a pre-fixed film layer on the plurality of the busbar-less back contact batteries, and slightly melting the pre-fixed film layer and then solidifying it to adhere to the back surface of the busbar-less back contact batteries, thereby fixing the positive electrode welding ribbon and the negative electrode welding ribbon;

[0046] Laying a second adhesive film and a second cover plate on the pre-fixed film layer;

[0047] Lamination and welding are performed to form a main grid-free back contact battery assembly; wherein the fluidity of the pre-fixed film layer during the initial lamination process is lower than the fluidity of the pre-fixed film layer during the initial lamination process.

[0048] In the busbarless back-contact battery assembly and its preparation method of the embodiments of the present application, the busbarless battery string is composed of busbarless back-contact batteries, the positive electrode welding ribbon is conductively connected to the positive electrode fine grid, and the negative electrode welding ribbon is conductively connected to the negative electrode welding ribbon, thereby realizing the convergence output of current. The positive electrode welding ribbon and the negative electrode welding ribbon are fixed to the busbar back-contact battery by a pre-fixed film layer. In this way, there is no need to set a busbar line on the back of the busbarless back-contact battery, and there is no need to print welding pads on the busbar, which can reduce the use of silver paste and reduce costs. At the same time, after the positive electrode welding ribbon and the negative electrode welding ribbon are laid, a pre-fixed film layer is used to fix the positive electrode welding ribbon and the negative electrode welding ribbon to the back side of the busbar-free back contact battery. The fluidity of the pre-fixed film layer during the initial lamination process is lower than the fluidity of the second adhesive film during the initial lamination process. In this way, during the initial lamination process, the fluidity of the pre-fixed film layer is lower, which can effectively prevent the positive electrode welding ribbon and the negative electrode welding ribbon from shifting during the production of the busbar-free back contact battery assembly, improve the positioning and alignment accuracy of the positive electrode welding ribbon and the negative electrode welding ribbon, and thus ensure the yield rate. At the same time, compared with the prior art method of using glue to pre-fix the negative electrode welding ribbon and the positive electrode welding ribbon, the use of a pre-fixed film layer to fix the negative electrode welding ribbon and the positive electrode welding ribbon can effectively avoid cold solder joints and poor EL. In other words, using glue to fix the welding ribbon can easily lead to cold solder joints and poor EL, while the technical solution of the present application can avoid these problems.

[0049] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of a module of a busbar-free back-contact battery assembly provided in an embodiment of the present application;

[0051] Figure 2 This is a schematic diagram of a module of a busbar-less battery string provided in an embodiment of the present application;

[0052] Figure 3 This is a schematic diagram of the structure of a busbar-free battery string provided in an embodiment of the present application;

[0053] Figure 4 yes Figure 3 Schematic cross-sectional view of the busbar-free battery string along line IV-IV;

[0054] Figure 5 1 is a cross-sectional schematic diagram of a busbar-less battery assembly provided in an embodiment of the present application;

[0055] Figure 6 This is another structural diagram of a busbar-less battery string provided in an embodiment of the present application;

[0056] Figure 7 1 is another schematic flow chart of a method for preparing a busbar-free battery assembly provided in an embodiment of the present application;

[0057] Figure 8 This is another schematic flow chart of the method for preparing a busbar-free battery assembly provided in an embodiment of the present application;

[0058] Figure 9 This is another schematic flow chart of the method for preparing a busbar-free battery assembly provided in an embodiment of the present application;

[0059] Figure 10 1 is another flow chart of the method for preparing a busbar-free battery assembly provided in an embodiment of the present application;

[0060] Figure 11 This is another flow chart of the method for preparing a busbar-free battery assembly provided in an embodiment of the present application.

[0061] Description of main component symbols:

[0062] Busbar-less back contact battery assembly 100, first cover plate 10, first adhesive film 20, busbar-less battery string 30, busbar-less back contact battery 31, back surface 311, positive electrode fine grid 312, negative electrode fine grid 313, positive electrode welding ribbon 32, negative electrode welding ribbon 33, pre-fixed film layer 34, first welding layer 35, second welding layer 36, first insulating layer 37, second insulating layer 38, second adhesive film 40, second cover plate 50 DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. In addition, it should be understood that the specific embodiments described herein are merely used to explain the present application and are not intended to limit the present application.

[0064] In the description of this application, it should be understood that the terms "upper", "lower", "back surface", "front surface", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application.

[0065] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0066] The disclosure below provides many different embodiments or examples for realizing different structures of the present application. In order to simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present application. In addition, the present application may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art will appreciate the application of other processes and / or the use scenarios of other materials.

[0067] See also Figure 1-Figure 5 The busbar-less back-contact battery assembly 100 in the embodiment of the present application may include a first cover plate 10, a first adhesive film 20, at least one busbar-less battery string 30, a second adhesive film 40 and a second cover plate 50 stacked in sequence.

[0068] like Figure 3 As shown, the busbar-less battery string 30 may include several busbar-less back contact batteries 31 ( Figure 3 Only two busbar-less back-contact cells 31 are shown, along with several positive electrode welding ribbons 32, several negative electrode welding ribbons 33, and a pre-fixed film layer 34. The back side 311 of the busbar-less back-contact cell 31 has several positive electrode fine grids 312 and negative electrode fine grids 313, which are alternately arranged in sequence. Specifically, the positive electrode fine grids 312 and the negative electrode fine grids 313 can be arranged in parallel and spaced apart.

[0069] like Figure 3As shown, in the busbarless battery string 30, two adjacent busbarless back-contact batteries 31 can be spaced apart. Of course, it is understood that in some embodiments, two adjacent busbarless back-contact batteries 31 can also be arranged in contact with each other, or the edges of two adjacent busbarless back-contact batteries 31 can be overlapped. The specific arrangement can be selected according to actual conditions and is not limited here.

[0070] In the busbarless battery string 30, the positive electrode ribbon 32 can be intersected with and electrically connected to the positive electrode thin grid 312, and the negative electrode ribbon 33 can be intersected with and electrically connected to the negative electrode thin grid 313. Several positive electrode ribbons 32 and several negative electrode ribbons 33 are arranged alternately and spaced apart.

[0071] Specifically, if Figure 3 As shown, the positive electrode fine grid 312 and the negative electrode fine grid 313 can be alternately arranged along the first direction, and the positive electrode welding strip 32 and the negative electrode welding strip 33 can be alternately arranged in parallel along the second direction. The first direction intersects the second direction, as shown in FIG. Figure 3 As shown, the first direction may be the longitudinal direction of the busbar-less back contact cell 31 , and the second direction may be the lateral direction of the busbar-less back contact cell 31 , and the two directions are perpendicular to each other.

[0072] Please combine Figure 3 and Figure 4 The pre-fixed film layer 34 is disposed on the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33. The pre-fixed film layer 34 is fixedly connected to the back surface 311 of the busbar-less back contact battery 31 to fix the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33 to the back surface 311. The second adhesive film 40 covers the pre-fixed film layer 34. The fluidity of the pre-fixed film layer 34 during the initial lamination process is lower than the fluidity of the second adhesive film 40 during the initial lamination process.

[0073] It should be noted that the “initial lamination process” refers to the stage before stable welding is formed between the positive electrode welding ribbon 32 and the positive electrode fine grid 112 and between the negative electrode welding ribbon 33 and the negative electrode fine grid 313 during the lamination welding process of the components.

[0074] In the busbarless back-contact cell assembly 100 of the embodiment of the present application, the busbarless cell string 30 is composed of busbarless back-contact cells 31. The positive electrode welding ribbon 32 is conductively connected to the positive electrode fine grid 312, and the negative electrode welding ribbon 33 is conductively connected to the negative electrode welding ribbon 33, thereby achieving current convergence output. The positive electrode welding ribbon 32 and the negative electrode welding ribbon 33 are fixed to the busbar back-contact cell 31 by a pre-fixed film layer 34. In this way, there is no need to set a busbar line on the back side 311 of the busbarless back-contact cell 31, and there is no need to print solder pads on the busbar, which can reduce the use of silver paste and reduce costs. At the same time, after the positive electrode welding strip 32 and the negative electrode welding strip 33 are laid, the positive electrode welding strip 32 and the negative electrode welding strip 33 are fixed on the back side 311 of the main grid-free back contact battery 31 by using a pre-fixed film layer 34. The fluidity of the pre-fixed film layer 34 in the initial lamination process is lower than the fluidity of the second adhesive film 40 in the initial lamination process. In this way, in the initial lamination process, the fluidity of the pre-fixed film layer 34 is low, which can effectively avoid the positive electrode welding strip 32 and the negative electrode welding strip 33 from being offset during the production of the main grid-free back contact battery assembly 100. That is, in the initial lamination process, the pre-fixed film layer 34 can isolate most of the flowing melt after the second adhesive film 40 is melted, and avoid the melt formed by the second adhesive film 40 from causing the positive electrode welding strip 32 and the negative electrode welding strip 33 to be offset, thereby improving the positioning and alignment accuracy of the positive electrode welding strip 32 and the negative electrode welding strip 33, thereby ensuring the yield. At the same time, compared with the prior art that uses a glue dispensing method to pre-fix the negative electrode welding strip 33 and the positive electrode welding strip 32, the use of a pre-fixed film layer 34 to fix the negative electrode welding strip 33 and the positive electrode welding strip 32 can effectively avoid cold solder joints and poor EL. In other words, using a glue dispensing method to fix the welding strips can easily lead to cold solder joints and poor EL, and the technical solution of the present application can avoid these problems.

[0075] Specifically, in the embodiment of the present application, “the positive electrode welding strip 32 is cross-arranged with the positive electrode fine grid 312 and is conductively connected to the positive electrode fine grid 312, and the negative electrode welding strip 33 is cross-arranged with the negative electrode fine grid 313 and is conductively connected to the negative electrode fine grid 313” means that, in the extension direction of the positive electrode welding strip 32, the positive electrode welding strip 32 is only conductively connected to the positive electrode fine grid 312 and is insulated and isolated from the negative electrode fine grid 313, and the negative electrode welding strip 33 is only conductively connected to the negative electrode fine grid 313 and is insulated and isolated from the positive electrode fine grid 312.

[0076] In some embodiments, the pre-fixed film layer 34 may be at least one of PVB film, EVA film, EPE film, EP film and POE film, and the second film 40 may be at least one of POE film, EVA film, EPE film, EP film, PE film and PVB film. It only needs to be able to make the fluidity of the pre-fixed film layer 34 during the initial lamination process lower than the fluidity of the second film 40 during the initial lamination process. No specific restrictions are made here.

[0077] See also Figure 3 In some embodiments, two adjacent busbar-less back-contact cells 31 may be spaced apart. The pre-fixing film 34 may only cover the busbar-less back-contact cells 31, leaving the gap between them. This reduces the use of the pre-fixing film 34 while ensuring the proper soldering of the solder ribbon, thereby reducing costs.

[0078] Of course, in some embodiments, the pre-fixed film layer 34 can also cover the busbar-less back contact cells 31 and the gap between two adjacent busbar-less back contact cells 31. In this way, when laying the pre-fixed film layer 34, it can be directly covered on the busbar-less cell string 31 in one piece, without having to lay the pre-fixed film layer 34 on each busbar-less back contact cell 31 separately, thereby reducing process costs.

[0079] Furthermore, in some embodiments, the pre-fixed film layer 34 may cover at least the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33. In this way, the pre-fixed film layer 34 may only cover the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33, and the use of the pre-fixed film layer 34 may be reduced, thereby reducing costs.

[0080] In some embodiments, the pre-fixed film layer 34 has a grammage of 50 g to 200 g per square meter.

[0081] In this way, it is possible to avoid the gram weight of the pre-fixed film layer 34 being too small, resulting in the thickness of the film layer being too thin and causing excessive difficulty in the process (for example, the difficulty of adsorption and laying is too great), and it is also possible to avoid the gram weight of the pre-fixed film layer 34 being too large, resulting in greater difficulty in the process during the lamination process (for example, too heavy makes adsorption and laying more difficult, and it is also easy to cause the film layer to be uneven). At the same time, it can also avoid excessive costs. That is to say, setting the gram weight of the pre-fixed film layer 34 per square meter within the range of 50g-200g can ensure the fixing effect of the welding strip while avoiding excessive difficulty in the process and preventing the cost from being too high.

[0082] Specifically, in such an embodiment, the gram weight of the pre-fixed film layer 34 per square meter may be, for example, 50g, 60g, 70g, 80g, 90g, 100g, 110g, 120g, 130g, 140g, 150g, 160g, 170g, 180g, 190g, 200g or any value between 50g-200g, wherein the gram weight of the pre-fixed film layer 34 per square meter is preferably 100g.

[0083] See also Figure 3 and Figure 4In some embodiments, a first welding layer 35 is provided on the positive electrode fine grid 312 at a position in contact with the positive electrode welding strip 32, and the positive electrode welding strip 32 is connected to the first welding layer 35, and a second welding layer 36 is provided on the negative electrode fine grid 313 at a position in contact with the negative electrode welding strip 33, and the negative electrode welding strip 33 is connected to the second welding layer 36.

[0084] In this way, during the manufacturing process, the pre-fixed film layer 34 can be used to achieve pre-fixed contact between the positive electrode welding strip 32 and the first welding layer 35, and between the negative electrode welding strip 33 and the second welding layer 36. Then, during the lamination process, the positive electrode welding strip 32 and the first welding layer 35 are welded together, and the negative electrode welding strip 33 and the second welding layer 36 are welded together to form a stable connection.

[0085] Specifically, if Figure 3 As shown, in such an embodiment, in the extension direction of the positive electrode welding strip 32, a first welding layer 35 is provided on each positive electrode fine grid 312 at a position intersecting with the positive electrode welding strip 32, and in the extension direction of the negative electrode welding strip 33, a second welding layer 36 is provided on each negative electrode fine grid 313 at a position intersecting with the negative electrode welding strip 33.

[0086] In the embodiment of the present application, both the first welding layer 35 and the second welding layer 36 can be solder paste. In this way, the solder paste has a lower soldering temperature, and low-temperature soldering can be used to achieve soldering between the solder strip and the solder paste without the need for high-temperature soldering. This can effectively prevent the battery string from becoming severely warped after soldering, thereby improving the yield and reducing the difficulty of manufacturing.

[0087] In such an embodiment, when manufacturing a busbar-free back-contact battery assembly 100, solder paste can be first printed at the position where the positive electrode fine grid 312 contacts the positive electrode welding strip 32 and at the position where the negative electrode fine grid 313 contacts the negative electrode welding strip 33, without performing a drying and curing process, and then the positive electrode welding strip 32 and the negative electrode welding strip 33 are laid, and then the welding process is performed during the lamination process. In this way, the uncured solder paste can achieve a better connection with the positive electrode welding strip 32 and the negative electrode welding strip 33 during the lamination welding process, avoiding cold solder joints and detachment of the welding strips. Of course, in some embodiments, when manufacturing a busbar-free back-contact battery assembly, solder paste can also be first printed at the position where the positive electrode fine grid 312 contacts the positive electrode welding strip 32 and at the position where the negative electrode fine grid 313 contacts the negative electrode welding strip 33, and then a drying process is performed, and the specific details are not limited here.

[0088] In some embodiments, the positive electrode welding ribbon 32 can completely cover the first welding layer 35, and the negative electrode welding ribbon 33 can completely cover the second welding layer 36. In this way, when the first welding layer 35 and the second welding layer 36 are made of uncured solder paste and are not dried and cured, the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33 are completely covered with the uncured solder paste to effectively prevent solder paste splashing.

[0089] Please continue reading Figure 3 In some embodiments, a first insulating layer 37 is provided on the positive electrode thin grid 312 at the intersection with the negative electrode welding ribbon 33. The negative electrode welding ribbon 33 is insulated and isolated from the positive electrode thin grid 312 by the first insulating layer 37. A second insulating layer 38 is provided on the negative electrode thin grid 313 at the intersection with the positive electrode welding ribbon 32. The positive electrode welding ribbon 32 is insulated and isolated from the positive electrode thin grid 312 by the second insulating layer 38.

[0090] Thus, the provision of the first insulating layer 37 can prevent the negative electrode welding strip 33 from contacting the positive electrode fine grid 312 , and the provision of the second insulating layer 38 can prevent the positive electrode welding strip 32 from contacting the negative electrode fine grid 313 .

[0091] Specifically, in such an embodiment, the first insulating layer 37 and the second insulating layer 38 can both be insulating adhesive layers, such as Figure 3 As shown, for each positive electrode welding strip 32, a plurality of second insulating layers 38 and a plurality of first welding layers 35 are alternately arranged in the extension direction of the positive electrode welding strip 32, and for each negative electrode welding strip 33, a plurality of first insulating layers 37 and second welding layers 36 are alternately arranged in the extension direction of the negative electrode welding strip 33.

[0092] Of course, in some embodiments, the positive electrode thin grid 312 may be disconnected at the intersection with the negative electrode welding ribbon 33, and the negative electrode thin grid 313 may be disconnected at the intersection with the positive electrode welding ribbon 32. In this way, by designing the positive electrode thin grid 312 and the negative electrode thin grid 313 to be disconnected, the positive electrode welding ribbon 32 and the negative electrode thin grid 313 can be prevented from contacting each other, and the negative electrode welding ribbon 33 and the positive electrode thin grid 312 can be prevented from contacting each other, thereby reducing the use of insulating glue.

[0093] See also Figure 6 In some embodiments, the plurality of positive electrode welding strips 32 may include a plurality of first positive electrode welding strips 321 and a plurality of second positive electrode welding strips 322 , the pre-fixed film layer 34 is arranged on the first positive electrode welding strip 321 to fix the first positive electrode welding strip 321 on the back side 311 , and the second positive electrode welding strip 322 is fixed on the back side 311 by dispensing glue 60 .

[0094] Also, please continue reading Figure 6 In some embodiments, the plurality of negative electrode welding strips 33 include a plurality of first negative electrode welding strips 331 and a plurality of second negative electrode welding strips 332 , the pre-fixed film layer 34 is disposed on the first negative electrode welding strips 331 to fix the first negative electrode welding strips 332 on the back side 311 , and the second negative electrode welding strips 332 are fixed on the back side 311 by dispensing glue 70 .

[0095] See also Figure 5 and Figure 7The present application also provides a method for preparing a busbar-free back contact battery assembly 100, which may include the following steps:

[0096] S10: providing a plurality of busbar-free back contact cells 31;

[0097] like Figure 3 As shown, the back side 311 of the mainbar-less back contact battery 31 has a plurality of positive electrode fine grids 312 and a plurality of negative electrode fine grids 313, and the plurality of positive electrode fine grids 312 and the plurality of negative electrode fine grids 313 are alternately arranged in sequence; two adjacent mainbar-less back contact batteries 31 can be arranged at intervals, or can be arranged in contact, or the edge portions of the two adjacent mainbar-less back contact batteries 31 can be overlapped.

[0098] S20: Laying a plurality of positive electrode welding ribbons 32 and a plurality of negative electrode welding ribbons 33 on the busbar-less back contact battery 31;

[0099] Among them, Figure 3 As shown, the positive electrode welding strip 32 is arranged to cross the positive electrode fine grid 312 and is conductively connected to the positive electrode fine grid 312, and the negative electrode welding strip 33 is arranged to cross the negative electrode fine grid 313 and is conductively connected to the negative electrode fine grid 313;

[0100] S30: Laying a pre-fixed film layer 34 on a plurality of busbar-less back contact cells 31, and slightly melting and then solidifying the pre-fixed film layer 34 to adhere to the back surface 311 of the busbar-less back contact cells 31, thereby fixing the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33, thereby forming a busbar-less cell string 30;

[0101] S40: Laying the busbar-less battery string 30 on the first cover plate 10 on which the first adhesive film 20 is placed;

[0102] The back surface 311 of the busbar-free back contact cell 31 faces away from the first adhesive film 20 ;

[0103] S50: Laying the second adhesive film 40 and the second cover plate 50 on the back side of the busbar-less battery string 31;

[0104] S60 : lamination and welding process to form a busbar-less back contact cell assembly 100 ; wherein the fluidity of the pre-fixed film layer 34 during the initial lamination process is lower than the fluidity of the pre-fixed film layer 34 during the initial lamination process with the second adhesive film 40 .

[0105] It should be noted that the “initial lamination process” refers to the stage before stable welding is formed between the positive electrode welding ribbon 32 and the positive electrode fine grid 112 and between the negative electrode welding ribbon 33 and the negative electrode fine grid 313 during the lamination welding process of the components.

[0106] In this way, after the positive electrode welding strip 32 and the negative electrode welding strip 33 are laid, the positive electrode welding strip 32 and the negative electrode welding strip 33 are pre-fixed on the back side 311 of the main grid back contact battery 31 by laying the pre-fixed film layer 34 and making the pre-fixed film layer 34 strong enough to melt and then solidify. The fluidity of the pre-fixed film layer 34 during the initial lamination process is lower than the fluidity of the second adhesive film 40 during the initial lamination process. Due to the presence of the pre-fixed film layer 34, the second adhesive film 40 can be prevented from melting during the lamination process to form a melt that drives the welding strip to move, thereby effectively avoiding the positive electrode welding strip 32 and the negative electrode welding strip 33 from being offset during the production of the main grid back contact battery assembly 100, and the positioning and alignment accuracy of the positive electrode welding strip 32 and the negative electrode welding strip 33 can be improved, thereby ensuring the yield.

[0107] Specifically, in the embodiment of the present application, the pre-fixed film layer 34 may preferably be directly made of a film layer having a lower fluidity than the second adhesive film 40. For example, the pre-fixed film layer 34 may be made of a PVB adhesive film, while the second adhesive film 40 may be made of an EVA adhesive film, a POE adhesive film, or the like. Of course, in some embodiments, the film material of the pre-fixed film layer 34 may also be the same as that of the second adhesive film 40. For example, both may be made of a PVB film. In such a case, because the pre-fixed film layer 34 is heated during the laying process to cause it to slightly melt and then solidify and bond to the back surface 311, since the pre-fixed film layer 34 has already undergone a slight melting and solidification process, the fluidity of the pre-fixed film layer 34 will also be lower than that of the second adhesive film 40 during the initial stage of subsequent lamination.

[0108] See also Figure 8 In some embodiments, step S30 may include the steps of:

[0109] S31: The pre-fixed film layer 34 is adsorbed by the adsorption pressing block, and the pre-fixed film layer 34 is placed on the main grid-free back contact battery 31 and heated. During the heating process, pressure is applied to the pre-fixed film layer 34 by the adsorption pressing block, so that the pre-fixed film layer 34 is slightly melted and then solidified to be bonded to the back side 311, thereby fixing the positive electrode welding strip 32 and the negative electrode welding strip 33, and then forming the main grid-free battery string 30.

[0110] In this way, the pre-fixed film layer 34 can be stably placed on the main grid-less back contact battery 31 through adsorption and pressure by the adsorption pressing block, and the pre-fixed film layer 34 can pre-fix the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33 on the back side of the back contact battery 31.

[0111] Specifically, the adsorption compact may be a compact with a plurality of adsorption holes, commonly known as a membrane palm, which can adsorb the membrane layer and place the membrane layer on the battery cell.

[0112] Furthermore, in such an embodiment, the temperature is maintained in the range of 50° C. to 150° C. when laying the pre-fixed film layer 34 so as to slightly melt the pre-fixed film layer 34 .

[0113] In this way, it is possible to avoid the situation where the temperature during the laying of the pre-fixed film layer 34 is too low, causing the adhesive film to fail to melt or the adhesive film to take too long to melt; it is also possible to avoid the situation where the temperature is too high, causing the pre-fixed film layer 34 to wrinkle; and it is possible to avoid the situation where the temperature is too high, causing the battery cell to warp, thereby increasing the difficulty of the process.

[0114] See also Figure 9 In some embodiments, before step S20, the preparation method may further include the following steps:

[0115] S70: preparing a first welding layer 35 at a position on the positive electrode fine grid 312 that contacts the positive electrode welding strip 32 , and preparing a second welding layer 36 at a position on the negative electrode fine grid 313 that contacts the negative electrode welding strip 33 ;

[0116] Step S20 includes the steps of:

[0117] S21 : Laying the positive electrode welding ribbon 32 at the position of the first welding layer 35 , and laying the negative electrode welding ribbon 33 at the position of the second welding layer 36 .

[0118] Specifically, in such an embodiment, the first welding layer 35 and the second welding layer 36 can both be formed by printing solder paste. In some embodiments, the first welding layer 35 and the second welding layer 36 are both formed by printing solder paste and then drying and curing it.

[0119] In other embodiments, the first welding layer 35 and the second welding layer 36 are both formed by printing solder paste without drying and curing. When the solder paste is not cured and dried, the connection performance between the solder strip and the solder paste can be guaranteed during the subsequent soldering process.

[0120] See also Figure 10 In some embodiments, before step S20, the preparation method may further include the following steps:

[0121] S80: forming a first insulating layer 37 on the positive electrode fine grid 312 at a position intersecting the negative electrode welding strip 33 , and forming a second insulating layer 38 on the negative electrode fine grid 313 at a position intersecting the positive electrode welding strip.

[0122] Thus, the provision of the first insulating layer 37 can prevent the negative electrode welding strip 33 from contacting the positive electrode fine grid 312 , and the provision of the second insulating layer 38 can prevent the positive electrode welding strip 32 from contacting the negative electrode fine grid 313 .

[0123] Specifically, in such an embodiment, both the first insulating layer 37 and the second insulating layer 38 can be insulating adhesive layers. During the manufacturing process, fine grids of the same polarity can be printed with insulating adhesive according to the coverage position of the solder strip. After printing, the insulating adhesive is heated in an oven or a curing furnace to form the first insulating layer 37 and the second insulating layer 38. After heating, the insulating adhesive has a hardness greater than 5H. It is understood that in this application, the order of S70 and S80 is not specific. S70 can be performed first, S80 can be performed first, or both can be performed simultaneously. There is no specific limitation here.

[0124] See also Figure 11 The present application also provides another method for preparing a busbar-free back contact battery assembly 100, which comprises the following steps:

[0125] S101: Laying a first adhesive film 20 on the first cover plate 10;

[0126] S102: laying a plurality of spaced apart busbar-free back contact cells 31 on the first adhesive film 20;

[0127] The back side 311 of the busbar-less back contact cell 31 has a plurality of positive electrode fine grids 312 and a plurality of negative electrode fine grids 313 , which are alternately arranged in sequence. The back side 311 of the busbar-less back contact cell 31 is away from the first adhesive film 20 .

[0128] S103: Laying a plurality of positive electrode welding ribbons 32 and a plurality of negative electrode welding ribbons 33 on the busbar-less back contact battery 31; wherein the positive electrode welding ribbons 32 are arranged to intersect with the positive electrode fine grid 312 and are conductively connected to the positive electrode fine grid 312, and the negative electrode welding ribbons 33 are arranged to intersect with the negative electrode fine grid 313 and are conductively connected to the negative electrode fine grid 313;

[0129] S104: Laying a pre-fixed film layer 34 on a plurality of busbar-less back contact cells 31, and slightly melting and then solidifying the pre-fixed film layer 34 to adhere to the back surface 311 of the busbar-less back contact cells 31, thereby fixing the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33;

[0130] S105: Laying the second adhesive film 40 and the second cover plate 50 on the pre-fixed film layer 34;

[0131] S106: lamination welding process to form a busbar-free back contact battery assembly 100;

[0132] The fluidity of the pre-fixed film layer 34 during the initial lamination process is lower than the fluidity of the pre-fixed film layer 34 during the initial lamination process with the second adhesive film 40 .

[0133] This preparation method differs from the preparation method in the above embodiment in that: the above preparation method first prepares a busbarless battery string 31 with a pre-fixed film layer 34, then places at least one busbarless battery string 31 on a first cover plate 10 provided with a first adhesive film 20, then lays a second adhesive film 40 and a second cover plate 50, and then performs lamination welding. The preparation method in this embodiment, on the other hand, first lays the busbarless back contact battery 31 on the first adhesive film 20, then places the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33, then lays the pre-fixed film layer 34 and allows the pre-fixed film layer 34 to slightly melt and then solidify to pre-fix the positive electrode welding ribbon 32 and the negative electrode welding ribbon 33 on the busbarless back contact battery 31, then lays the second adhesive film 40 and the second cover plate 50, and finally performs lamination welding.

[0134] It can be understood that in such an embodiment, the laying method of the pre-fixed membrane layer 34 is the same as the laying method in the above embodiment. At the same time, in this embodiment, steps S70 and S80 in the above embodiment can also be used to produce the first welding layer 35, the second welding layer 36, the first insulating layer 37 and the second insulating layer 38, which will not be elaborated here.

[0135] Throughout this specification, reference to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, the illustrative use of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0136] In addition, the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a busbar-free back contact battery assembly, characterized in that: include: A plurality of busbar-free back-contact batteries are provided; the back of the busbar-free back-contact batteries has a plurality of positive electrode fine grids and a plurality of negative electrode fine grids, and the plurality of positive electrode fine grids and the plurality of negative electrode fine grids are alternately arranged in sequence; A first welding layer is prepared at a position on the positive electrode fine grid in contact with the positive electrode welding strip, and a second welding layer is prepared at a position on the negative electrode fine grid in contact with the negative electrode welding strip; wherein the first welding layer and the second welding layer are both formed by printing solder paste without drying and curing; A positive electrode welding strip is laid at the position of the first welding layer, and a negative electrode welding strip is laid at the position of the second welding layer; wherein the positive electrode welding strip is arranged to cross the positive electrode fine grid and is electrically connected to the positive electrode fine grid, and the negative electrode welding strip is arranged to cross the negative electrode fine grid and is electrically connected to the negative electrode fine grid; Laying a pre-fixed film layer on the plurality of busbar-less back-contact cells, and slightly melting and then solidifying the pre-fixed film layer to adhere to the back surface of the busbar-less back-contact cells, thereby fixing the positive electrode welding ribbon and the negative electrode welding ribbon, thereby forming a busbar-less cell string; Laying the busbar-less battery string on a first cover plate with a first adhesive film placed thereon, with the back surface of the busbar-less back-contact battery facing away from the first adhesive film; Laying a second adhesive film and a second cover plate on the back side of the busbar-free back contact battery string; Lamination welding process to form a main grid-free back contact battery assembly; wherein, the fluidity of the pre-fixed film layer in the initial lamination process is lower than the fluidity of the second adhesive film in the initial lamination process, and the pre-fixed film layer is used to isolate the flowing melt after the second adhesive film is melted in the initial lamination process. The initial lamination process refers to the stage before stable welding is formed between the positive electrode welding strip and the positive electrode fine grid and between the negative electrode welding strip and the negative electrode fine grid during the lamination welding process.

2. The method for preparing a busbar-free back contact battery assembly according to claim 1, wherein: The step of laying a pre-fixed film layer on the plurality of busbar-less back contact batteries and slightly melting the pre-fixed film layer to adhere to the back surface of the busbar-less back contact batteries, thereby fixing the positive electrode welding ribbon and the negative electrode welding ribbon, comprises: The pre-fixed film layer is adsorbed by an adsorption pressing block, and the pre-fixed film layer is placed on the main grid-free back contact battery and heated. During the heating process, pressure is applied to the pre-fixed film layer by the adsorption pressing block, so that the pre-fixed film layer is slightly melted and then solidified to adhere to the back side, thereby fixing the positive electrode welding strip and the negative electrode welding strip.

3. The method for preparing a busbar-free back contact battery assembly according to claim 2, wherein: When laying the pre-fixed film layer, the temperature is maintained in the range of 50° C. to 150° C. so that the pre-fixed film layer is slightly melted.

4. The method for preparing a busbar-free back contact battery assembly according to claim 1, wherein: Before the step of laying a plurality of positive electrode welding strips and a plurality of negative electrode welding strips on the busbar-less back contact battery, the preparation method further comprises: A first insulating layer is prepared on the positive electrode fine grid at a position where it intersects with the negative electrode welding strip, and a second insulating layer is prepared on the negative electrode fine grid at a position where it intersects with the positive electrode welding strip.

5. A method for preparing a busbar-free back contact battery assembly, characterized in that: include: Laying a first adhesive film on the first cover plate; Laying a plurality of busbar-free back contact cells arranged at intervals on the first adhesive film; the back of the busbar-free back contact cells has a plurality of positive electrode fine grids and a plurality of negative electrode fine grids, the plurality of positive electrode fine grids and the plurality of negative electrode fine grids are alternately arranged at intervals in sequence, and the back of the busbar-free back contact cells faces away from the first adhesive film; A first welding layer is prepared at a position on the positive electrode fine grid in contact with the positive electrode welding strip, and a second welding layer is prepared at a position on the negative electrode fine grid in contact with the negative electrode welding strip; wherein the first welding layer and the second welding layer are both formed by printing solder paste without drying and curing; A positive electrode welding strip is laid at the position of the first welding layer, and a negative electrode welding strip is laid at the position of the second welding layer; wherein the positive electrode welding strip is arranged to cross the positive electrode fine grid and is electrically connected to the positive electrode fine grid, and the negative electrode welding strip is arranged to cross the negative electrode fine grid and is electrically connected to the negative electrode fine grid; Laying a pre-fixed film layer on the plurality of the busbar-less back contact batteries, and slightly melting the pre-fixed film layer and then solidifying it to adhere to the back surface of the busbar-less back contact batteries, thereby fixing the positive electrode welding ribbon and the negative electrode welding ribbon; Laying a second adhesive film and a second cover plate on the pre-fixed film layer; Lamination welding process to form a main grid-free back contact battery assembly; wherein, the fluidity of the pre-fixed film layer in the initial lamination process is lower than the fluidity of the second adhesive film in the initial lamination process, and the pre-fixed film layer is used to isolate the flowing melt after the second adhesive film is melted in the initial lamination process. The initial lamination process refers to the stage before stable welding is formed between the positive electrode welding strip and the positive electrode fine grid and between the negative electrode welding strip and the negative electrode fine grid during the lamination welding process.

6. A busbar-less back contact battery assembly, characterized in that: The busbar-free back-contact battery assembly is manufactured by the preparation method according to any one of claims 1 to 5.

7. The busbar-less back contact battery assembly according to claim 6, characterized in that: The gram weight of the pre-fixed film layer per square meter is 50g-200g.

8. The busbar-less back contact battery assembly according to claim 6, characterized in that: The positive electrode welding strip completely covers the first welding layer, and the negative electrode welding strip completely covers the second welding layer.

9. The busbar-less back contact battery assembly according to claim 6, characterized in that: A first insulating layer is provided on the positive electrode thin grid at a position where the positive electrode thin grid intersects with the negative electrode welding strip, and the negative electrode welding strip is insulated and isolated from the positive electrode thin grid by the first insulating layer; A second insulating layer is provided on the negative electrode fine grid at a position where the negative electrode fine grid intersects with the positive electrode welding strip, and the positive electrode welding strip is insulated and isolated from the positive electrode fine grid by the second insulating layer.

10. The busbar-less back contact battery assembly according to claim 6, characterized in that: The positive electrode thin grid is broken at a position intersecting with the negative electrode welding strip, and the negative electrode thin grid is broken at a position intersecting with the positive electrode welding strip.

11. The busbar-less back contact battery assembly according to claim 6, characterized in that: The pre-fixed film layer includes at least one of PVB film, EVA film, EPE film, EP film and POE film, and the second film includes at least one of POE film, EVA film, EPE film, EP film, PE film and PVB film.

12. The busbar-less back contact battery assembly according to claim 6, wherein: Two adjacent main-grid-free back-contact batteries are arranged at intervals; Wherein, the pre-fixed film layer covers the busbar-less back contact cell; or The pre-fixed film layer simultaneously covers the busbar-free back contact cell and the gap between two adjacent busbar-free back contact cells; or The pre-fixed film layer at least covers the positive electrode welding strip and the negative electrode welding strip.

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