Battery piece unit, main-grid-free back contact battery block, battery module and preparation method

Abstract

The invention relates to the technical field of solar cells, and particularly provides a cell piece unit, a main-grid-free back contact cell block, a cell module and a preparation method, and the cell piece unit, the main-grid-free back contact cell block, the cell module and the preparation method are characterized in that welding strips with the same polarity are electrically connected with fine grids through metal connecting layers to realize unified connection of positive fine grids and negative fine grids; the welding strips and the fine grids which are opposite in polarity are connected through the insulating glue layers and the bonding layers, insulating isolation between the welding strips and the fine grids is achieved through the insulating glue layers, fixed connection is achieved through the bonding glue layers, and the fixing pulling force of the welding strips is improved; therefore, the structural stability of the whole battery piece unit is improved, and the adhesive layer and the welding strip are fixedly connected while the plurality of battery piece units are welded, so that the production efficiency is greatly improved; and meanwhile, the difference between the material surface energy of the insulating adhesive layer and the material surface energy of the bonding layer is less than 20mN / m, so that the tension of the solder strip is effectively increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a solar cell unit, a main grid-free back contact solar cell, a solar cell module and a preparation method thereof. Background Art

[0002] Existing back-contact cells with main grids use infrared serial welding technology. After welding, the cell deforms greatly (more than 2 mm) and needs to be leveled with external force. In addition, the product consumes a lot of silver, which increases costs.

[0003] The existing back-contact cells without main grids are initially bonded by laminating, taping or UV glue, and then laminated and welded by a laminator. The welding efficiency of this type of cell is low and the process is complicated. The bonding stability also needs to be improved. In addition, it is impossible to detect whether the product is effectively contacted before lamination. It needs to be detected after lamination. However, if there is poor contact, it cannot be repaired, which increases the battery cost.

[0004] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or known technology. Summary of the invention

[0005] The purpose of the present invention is to provide a battery cell unit, a main grid-free back contact battery, a battery module and a preparation method to solve the technical problems of low welding efficiency, complex process and unstable tensile performance of existing battery cells.

[0006] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a battery cell unit, comprising: a battery substrate, and a fine grid electrode layer and a welding strip layer sequentially arranged on the back side of the battery substrate; The fine grid electrode layer includes a plurality of positive fine grids and a plurality of negative fine grids arranged alternately at intervals along the second direction; the welding strip layer includes a plurality of positive welding strips and a plurality of negative welding strips arranged alternately at intervals along the first direction; the first direction is perpendicular to the second direction; The overlapped area of ​​the positive electrode welding strip and the positive electrode fine grid is connected by a metal connecting layer, and the overlapped area of ​​the positive electrode welding strip and the negative electrode fine grid is connected by an insulating glue layer and an adhesive layer, and the insulating glue layer is closer to the battery substrate than the adhesive layer; The overlapping area of ​​the negative electrode welding strip and the negative electrode fine grid is connected through a metal connecting layer, and the overlapping area of ​​the negative electrode welding strip and the positive electrode fine grid is connected through an insulating glue layer and an adhesive layer; The surface energy of the insulating glue layer material differs from the surface energy of the adhesive layer material by less than 20 mN / m, and the surface energy of the insulating glue layer material is less than the surface energy of the adhesive layer material.

[0007] Optionally, the material of the metal connection layer is solder paste, the material of the insulating adhesive layer is one of epoxy resin-based insulating adhesive, silicone-based insulating adhesive, polyurethane-based insulating adhesive, and polyimide-based insulating adhesive, and the material of the bonding layer is UV~heat-curing dual-curing adhesive, or two-component heat-curing adhesive.

[0008] Optionally, the size of the adhesive layer includes: a size along the first direction of 0.2-0.5 mm, a size along the second direction of 0.6-3 mm, and a spacing between adjacent positive electrode fine grids and negative electrode fine grids of 0.5 mm-0.8 mm.

[0009] In a second aspect, the present invention further provides a busbar-free back contact battery block, comprising: m rows×n columns of battery cell units as described in the first aspect; wherein n battery cell units are arranged along a first direction, and m battery cell units are arranged along a second direction; N battery cell units arranged along the first direction form a group of battery strings, and a strip connection component is arranged between two adjacent battery strings arranged along the second direction. The strip connection component includes a plurality of first connection segments arranged at intervals along the first direction, and the adjacent first connection segments are fixedly connected by a first insulating connector; the first connection segment is used to electrically connect the welding strips of opposite polarities of two adjacent battery cell units along the second direction.

[0010] Optionally, the first connecting section includes a first supporting bar and a plurality of first connecting pieces fixed on the first supporting bar, and the first supporting bar is a long strip structure extending along a first direction; The plurality of first connecting sheets are spaced apart along the length direction of the first supporting bar, and the length direction of the first connecting sheets is perpendicular to the length direction of the first supporting bar, and are used to respectively connect welding strips of opposite polarities of two adjacent battery cell units along the second direction.

[0011] Optionally, two battery cell units adjacent to each other along the second direction are overlapped, and the connecting sheet is a step structure or a flat plate structure.

[0012] Optionally, the first connecting section is a whole strip structure, which is used to respectively connect welding strips of opposite polarities of two battery cell units adjacent to each other along the second direction.

[0013] In a third aspect, the present invention further provides a battery module, comprising two busbar-free back contact battery blocks as described in the second aspect; The two busbar-free back-contact battery blocks are respectively a first battery block and a second battery block; the first battery block and the second battery block are arranged side by side along a second direction, and the m-th rows of the two battery blocks are close to each other for splicing, and the first to m-th rows of the first battery block and the second battery block are arranged in sequence from an end away from each other to an end close to each other; The welding strips of opposite polarities of each two adjacent battery cell units in the first row of the first battery block and the first row of the second battery block are connected by a plurality of first bus bars extending along the first direction; The welding strips of the same polarity of the battery cell units of the mth row of the first battery block and the battery cell units of the mth row of the second battery block are connected through the same long strip bus assembly; the long strip bus assembly is located between the first battery block and the second battery block; The long strip bus assembly includes a plurality of second bus bars arranged along the second direction. Starting from the second battery cell unit in the mth row, the second bus bars corresponding to every two battery cell units are connected by a conductive member or formed as one piece, and the second bus bars corresponding to the remaining adjacent battery cell units are fixedly connected by a second insulating connector, and the second bus bars corresponding to the battery cell units in the 1st column and the nth column are respectively led out as the entire positive and negative electrodes.

[0014] Optionally, the second bus bar includes a second support bar and a plurality of second connecting pieces fixed on the second support bar, and the second support bar is a long strip structure extending along the first direction; A plurality of second connecting plates are arranged at intervals along the length direction of the second support bar, and the length direction of the second connecting plates is perpendicular to the length direction of the second support bar, and are used to connect the welding strips of the same polarity of the first battery block and the second battery block in parallel or to connect the welding strips of different polarities in series.

[0015] In a fourth aspect, the present invention further provides a method for preparing a battery module, which is used to prepare the battery module as described in the second aspect, comprising: S100, pre-preparing a solder paste layer at a preset position of a fine grid electrode layer on the back side of a cell unit on which a fine grid electrode layer and an insulating adhesive layer have been prepared; the fine grid electrode layer comprises a plurality of positive electrode fine grids and a plurality of negative electrode fine grids alternately arranged at intervals along a second direction; S200, preparing an adhesive layer on the insulating adhesive layer of the battery cell unit and curing and forming the adhesive layer; S300, prefabricating a positive electrode welding strip and a negative electrode welding strip, and placing the positive electrode welding strip and the negative electrode welding strip alternately and spaced at preset positions on the fine gate electrode layer along a first direction, and contacting the corresponding solder paste layer and adhesive layer; wherein the second direction is perpendicular to the first direction; S400, arranging the battery cell units obtained in S300 in a manner of m rows×n columns, and starting from the first row or the mth row, sequentially connecting the positive electrode welding strips and the negative electrode welding strips of the battery cell units in two adjacent rows one by one through a strip connection assembly, thereby forming a busbar-free back contact battery block; S500, disposing a plurality of first bus bars outside the first row of the busbar-free back-contact battery block, and connecting the welding strips of different polarities of each two adjacent battery cell units in the first row in series or connecting the welding strips of the same polarity in parallel through the first bus bars; S600, place two identical busbar-free back-contact battery blocks without one end of the first bus bar side by side, and connect them in series or in parallel through a long strip bus assembly, and make the long strip bus assembly connect every two battery cell units in series starting from the second battery cell unit in the mth row of each busbar-free back-contact battery block.

[0016] Optionally, in step S400, the first connecting piece of the strip connection assembly is directly connected to the corresponding soldering strip by soldering.

[0017] Optionally, in step S600, the second connecting piece of the long strip busbar assembly is directly connected to the corresponding soldering strip by soldering.

[0018] The embodiments of the present invention have at least the following beneficial effects: The present invention adopts the above technical scheme, utilizes the welding strips of the same polarity to electrically connect with the fine grids through the metal connection layer, realizes the unified connection of each positive electrode fine grid and the negative electrode fine grid, thereby facilitating the connection in series or in parallel with the welding strips of other battery cell units through the welding strips, and the welding strips and the fine grids of opposite polarities are connected through the insulating glue layer and the adhesive layer. On the one hand, the insulating glue layer realizes the insulation isolation between the two, and on the other hand, the adhesive glue layer realizes the fixed connection between the two, thereby improving the fixing tension of the welding strip; thereby improving the structural stability of the entire battery cell unit, compared with the prior art of dispensing glue on the back of the battery The method of the present invention is to coat the adhesive layer on the welding strip, but the defects are that the welding is performed one by one, the adhesive is dispensed and then solidified, the welding efficiency is low, the process is more complicated, and the tensile performance is unstable. The present invention arranges the adhesive layer on the insulating adhesive layer, which can simultaneously weld multiple battery cell units and complete the fixed connection between the adhesive layer and the welding strip, thereby greatly improving the production efficiency. At the same time, since the difference between the material surface energy of the insulating adhesive layer and the material surface energy of the adhesive layer is less than 20mN / m, and the material surface energy of the insulating adhesive layer is less than the material surface energy of the adhesive layer, the tensile force of the welding strip can be effectively increased, thereby facilitating the improvement of the stability of the battery cell.

[0019] After the battery string in the second direction is connected by welding in the prior art, the battery string needs to be arranged for secondary arranging to converge, and the spacing of the battery cell units along the first direction cannot be too small, because the battery cells on the battery string can not be fixed in position only by welding ribbon connection, so the battery cell unit may contact the electrode of the adjacent battery cell unit in the secondary arrangement or the subsequent transfer process, causing short circuit and other defects; while the present invention uses a strip connection component to weld the welding ribbons of the same polarity on the entire battery cell unit in parallel, and then connects the adjacent battery cell units in the second direction in series and parallel according to the component electrical connection design. At the same time, it plays a role in current conduction. If a single point or a single strip of welding ribbon on the battery cell unit fails, the strip connection component can play a role in uniformly reinforcing the current collection of the battery cell unit, minimizing the loss caused by the failure of the welding point of the welding rod. By connecting the strip connection component, the layout can be completed directly during the welding process, without the need for secondary layout, which can effectively improve production efficiency. And the battery cell units can be set with zero spacing or very small spacing, or even stacked connection; it can increase the effective power generation area of ​​the battery module and improve the power density of the battery module.

[0020] The prior art requires that the battery string position be fixed with tape after secondary arrangement before lamination can be performed, otherwise the battery cell units may shift during the movement process, causing defects; the present invention uses a strip connection component to simultaneously complete the layout and fixation of the entire battery module during the welding process of the welding strip, that is, the strip connection component is used as a metal conductor and can also fix the battery cell units and battery strings, eliminating the battery string arrangement and tape fixing processes, further improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the structure of a battery cell unit provided by an embodiment of the present invention; Figure 2 The embodiment of the present invention provides Figure 1 Schematic cross-sectional view of the overlapped areas of the positive electrode welding strip and the positive electrode fine grid and the negative electrode fine grid; Figure 3 A schematic diagram of the structure of a battery block provided by an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a battery string of a battery block provided by an embodiment of the present invention; Figure 5A schematic diagram of a structure in which battery strings of a battery block provided by an embodiment of the present invention are connected along a second direction; Figure 6 A schematic diagram of the structure of a strip-shaped connection assembly between battery strings of a battery block provided by an embodiment of the present invention; Figure 7 A schematic diagram of a local method for connecting first connecting segments provided by an embodiment of the present invention; Figure 8 A schematic diagram of the connection between a first connecting piece and a welding strip of a battery cell unit provided by an embodiment of the present invention; Fig. 9 A schematic diagram of the connection between a first connecting sheet and a welding ribbon of another battery cell unit provided by an embodiment of the present invention; Fig.10 A schematic diagram of another connection between a first connection section and a corresponding welding strip provided by an embodiment of the present invention; Fig.11 A schematic diagram of the structure of a battery cell module provided by an embodiment of the present invention; Fig.12 A schematic structural diagram of a long strip busbar assembly of a battery cell module provided by an embodiment of the present invention; Fig.13 A schematic diagram of the structure of a second bus bar of a long strip bus assembly of a battery cell module provided by an embodiment of the present invention; Fig.14 A flow chart of a method for preparing a battery module provided in an embodiment of the present invention.

[0023] Description of reference numerals: 100~battery cell unit; 100a~battery string; 110~battery substrate; 121~positive electrode welding strip; 122~negative electrode welding strip; 131~metal connecting layer; 132~insulating glue layer; 133~adhesive layer; 140~positive electrode fine grid; 150~negative electrode fine grid; 200~strip connecting assembly; 210~first connecting section; 211~first supporting bar; 212~first connecting piece; 220~first insulating connecting piece; 231~cushion; 300~battery block; 400~long strip bus assembly; 410~second bus bar; 411~second supporting bar; 412~second connecting piece; 420~second insulating connecting piece; 430~conductive member. DETAILED DESCRIPTION

[0024] In the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. Among them, the terms "optional" and "optional" all mean that they may be included or not included (or may be present or not).

[0027] The first aspect, such as Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a battery cell unit 100, including: a battery substrate 110, and a fine grid electrode layer and a welding strip layer sequentially arranged on the back side of the battery substrate 110.

[0028] Specifically, the fine grid electrode layer includes a plurality of positive fine grids 140 and a plurality of negative fine grids 150 arranged alternately at intervals along the second direction, that is, a negative fine grid 150 is provided between any two adjacent positive fine grids 140, or a positive fine grid 140 is provided between any two adjacent negative fine grids 150. The welding strip layer includes a plurality of positive welding strips 121 and a plurality of negative welding strips 122 arranged alternately at intervals along the first direction, that is, a negative welding strip 122 is provided between any two adjacent positive welding strips 121, or a positive welding strip 121 is provided between any two adjacent negative welding strips 122, and all the positive fine grids 140 are connected by the same positive welding strip 121, and all the negative fine grids 150 are connected by the same negative welding strip 122. Optionally, the first direction is Figure 1 The horizontal direction in the second direction is Figure 1 In the vertical direction, namely, the positive electrode fine grid 140 and the negative electrode fine grid 150.

[0029] Furthermore, the overlapping area of ​​the positive electrode welding strip 121 and the positive electrode fine grid 140 is connected by the metal connecting layer 131, and the overlapping area of ​​the positive electrode welding strip 121 and the negative electrode fine grid 150 is connected by the insulating glue layer 132 and the adhesive layer 133. The insulating glue layer 132 is closer to the battery substrate 110 than the adhesive layer 133, that is, all the positive electrode fine grids 140 are electrically connected through the positive electrode welding strip 121, and the overlapping area of ​​the positive electrode welding strip 121 and the negative electrode fine grid 150 of opposite polarity is isolated by the insulating glue layer 132 and fixed by the adhesive layer 133.

[0030] Similarly, the area where the negative electrode welding strip 122 overlaps with the negative electrode fine grid 150 is connected through the metal connecting layer 131, and the area where the negative electrode welding strip 122 overlaps with the positive electrode fine grid 140 is also connected through the insulating glue layer 132 and the adhesive layer 133, that is, all the negative electrode fine grids 150 are electrically connected through the negative electrode welding strip 122, and the area where the negative electrode welding strip 122 overlaps with the positive electrode fine grid 140 of opposite polarity is isolated by the insulating glue layer 132 and fixed by the adhesive layer 133.

[0031] It should be noted that the difference between the material surface energy of the insulating adhesive layer 132 and the material surface energy of the adhesive layer 133 is less than 20mN / m, and the material surface energy of the insulating adhesive layer 132 is less than the material surface energy of the adhesive layer 133, which is conducive to improving the bonding strength between the adhesive and the soldering tape and the insulating adhesive, thereby improving the soldering tape tension. Among them, the difference in surface energy of the two materials is less than 20mN / m (millinewton / meter), indicating that the two materials have similar polarity. Similar polarity means that they have similar properties in terms of surface energy or molecular polarity, which is conducive to the interaction between them and the enhancement of bonding performance, usually by establishing good intermolecular forces between the adhesive and the material surface, thereby promoting strong bonding.

[0032] The battery cell unit 100 provided in the embodiment of the present invention utilizes a welding ribbon and a fine grid of the same polarity to be electrically connected through a metal connection layer 131, thereby realizing a unified connection between each positive electrode fine grid 140 and a negative electrode fine grid 150, thereby facilitating a series connection with welding ribbons of other battery cell units 100 through welding ribbons, and welding ribbons and fine grids of opposite polarities are connected through an insulating glue layer 132 and an adhesive layer 133. On the one hand, the insulating glue layer 132 realizes insulation isolation between the two, and on the other hand, the adhesive layer realizes a fixed connection between the two, thereby improving the structural stability of the entire battery cell unit 100. Compared with the prior art, the method of dispensing glue on the back of the battery is more convenient. The method of manufacturing a plurality of battery cell units 100 or applying an adhesive layer to the welding tape has the disadvantages of first soldering one by one and then applying the adhesive and curing the soldering tape, which results in low soldering efficiency, more complicated process and unstable tensile performance of the welding tape. The present invention arranges the adhesive layer on the insulating adhesive layer 132, which can simultaneously solder multiple battery cell units 100 and complete the fixed connection between the adhesive layer and the welding tape, thereby greatly improving the production efficiency. At the same time, since the material surface energy of the insulating adhesive layer 132 and the material surface energy of the adhesive layer 133 differ by less than 20mN / m, and the material surface energy of the insulating adhesive layer 132 is less than the material surface energy of the adhesive layer 133, the bonding strength between the adhesive and the welding tape and the insulating adhesive can be improved, thereby further improving the tensile strength of the welding tape.

[0033] Optionally, the material of the metal connection layer 131 is solder paste, the material of the insulating adhesive layer 132 is one of epoxy resin-based insulating adhesive, silicone-based insulating adhesive, polyurethane-based insulating adhesive, and polyimide-based insulating adhesive, and the material of the adhesive layer 133 is UV~heat-curing dual-curing adhesive, or two-component heat-curing adhesive.

[0034] The following is a detailed description of the properties of the bonding layer 133 materials: For UV-heat curing dual-curing adhesive, this material effectively combines UV curing and heat curing, so that the adhesive has different curing properties at different stages, which not only ensures rapid curing and processing performance in the initial stage, but also directly bonds with welding through subsequent heat treatment, and undergoes irreversible cross-linking reaction to form a final stable structure, which will not melt again even in the subsequent high-temperature lamination process. Effectively improve production yield and conversion efficiency.

[0035] As for two-component heat-curing adhesives, different cross-linking reactions are triggered by different curing temperatures to achieve initial low-temperature curing, which not only ensures rapid initial curing and processing performance, but also directly welds and bonds through subsequent secondary heat treatment, and undergoes irreversible cross-linking reactions to form the final stable structure.

[0036] Optionally, the dimensions of the adhesive layer 133 include: a dimension along the first direction of 0.2-0.5 mm, a dimension along the second direction of 0.6-3 mm, and a spacing between adjacent positive electrode fine grids 140 and negative electrode fine grids 150 of 0.5 mm-0.8 mm.

[0037] Optionally, the thickness of the insulating glue layer 132 is 10~30um, and the size is (0.4~0.6) mm × (3.5~4.5) mm; the thickness of the adhesive layer 133 is 10~40um, and the size is (0.2~0.5) mm×(0.6~3) mm; the size of the solder paste layer is (0.1~0.5mm)×(0.5~2) mm, and the thickness is 20~50um.

[0038] Optionally, the infrared series welding process conditions are: 150°C~180°C, 1.8~2.5 seconds; the UV curing energy of the adhesive layer 133 is 1000~4000mj; the low-temperature curing temperature of the adhesive layer 133 is: 50~80°C, and the time is 3~8min.

[0039] The battery cell unit 100 provided in the embodiment of the present invention has a laminated insulating connection structure of an insulating glue layer 132 and an adhesive layer 133, so that during infrared series soldering, the adhesive layer 133 mainly plays a bonding role between the soldering tape and the battery cell, and the adhesive glue used in the adhesive layer 133 is in a solidified state at low temperatures. In this way, even if the high temperature causes the adhesive layer 133 to melt, it is still in a solidified state after the series soldering is cooled down. During solidification, the soldering tape and the battery cell are bonded together by the adhesive glue, and no secondary hot melting phenomenon will occur.

[0040] The second aspect, such as Figure 3~Figure 6 As shown, an embodiment of the present invention further provides a busbar-free back contact battery block, comprising: m rows×n columns of battery cell units 100 as described in the first aspect; wherein n battery cell units 100 are arranged along a first direction, and m battery cell units 100 are arranged along a second direction, and the first direction is perpendicular to the second direction (the first direction is a horizontal direction, and the second direction is a vertical direction). The specific structure of the battery cell unit 100 can be found in the contents of the aforementioned embodiment, and will not be repeated here.

[0041] Specifically, n battery cell units 100 arranged along the first direction form a battery string 100a, and a strip connection component 200 is arranged between two adjacent battery strings 100a arranged along the second direction. The strip connection component 200 is used to electrically connect the battery cell units 100 adjacent to each other along the second direction to achieve series connection of the battery cell units 100.

[0042] Furthermore, the strip connection assembly 200 includes a plurality of first connection segments 210 arranged at intervals along a first direction, and adjacent first connection segments 210 are fixedly connected by a first insulating connector 220; the first connection segments 210 are used to electrically connect the welding strips of opposite polarities of two adjacent battery cell units 100 along a second direction, thereby realizing series connection of the battery cell units 100.

[0043] Alternatively, if Figure 7 As shown, the first connecting section 210 includes a first supporting bar 211 and a plurality of first connecting pieces 212 fixed on the first supporting bar 211 . The first supporting bar 211 is a long strip structure extending along a first direction and serves as a mounting base for the first connecting pieces 212 .

[0044] A plurality of first connecting pieces 212 are arranged at intervals along the length direction of the first support bar 211, and the length direction of the first connecting piece 212 is perpendicular to the length direction of the first support bar 211, and are used to respectively connect the welding strips of opposite polarities of two adjacent battery cell units 100 along the second direction. Optionally, the first connecting piece 212 and the first support bar 211 can be connected by welding or integrally formed into an integral structure.

[0045] like Figure 7 As shown, the first group of transverse battery strings 100a formed by the six battery cell units 100 in the horizontal direction (or horizontal direction) in the first row and the second group of transverse battery strings 100a formed by the six battery cell units 100 in the horizontal direction (or horizontal direction) in the second row are connected together by the first connecting piece 212 of the first connecting section 210. Then the second group of transverse battery strings 100a and the third group of transverse battery strings 100a are connected together by the first connecting section 210, and are connected to the eleventh group of transverse battery strings 100a to form a battery block 300, and then connected in parallel with the second battery block 300. Through the above arrangement and connection method, the position of the battery cell is directly fixed, which is simpler in operation. The two battery cell units 100 in the horizontal direction of the first connecting section 210 are not electrically connected, so the two adjacent first connecting sections 210 are insulated and connected by the first insulating connector 220.

[0046] Alternatively, if Figure 8 As shown, two battery cell units 100 adjacent to each other in the second direction are overlapped, and the first connecting piece 212 is a step structure. Such a first connecting piece 212 requires special processing, but does not require an additional pad layer 231 to form a good contact and electrical connection.

[0047] Alternatively, if Fig. 9 As shown, two battery cell units 100 adjacent to each other in the second direction are overlapped, and the first connecting sheet 212 is a flat structure. The first connecting sheet 212 does not require special processing, but a cushion layer 231 needs to be provided to adjust the connection position of the first connecting sheet 212.

[0048] Alternatively, if Fig.10As shown, the first connecting section 210 is a whole strip structure, the width of the whole strip structure is relatively wide, and no connecting sheet is required. The welding strips of opposite polarities of two battery cell units 100 adjacent to each other along the second direction are respectively connected to the corresponding whole strip structure, thereby realizing the series connection of the two battery cell units ( Fig.10 In the figure, the positive electrode welding strip 121 of one battery cell unit 100 is connected to the negative electrode welding strip 122 of another battery cell unit 100 through the first connecting section 210 of the strip connecting component 200), which can avoid the alignment connection between the connecting piece and the corresponding welding strip, and the operation is more convenient.

[0049] The third aspect, such as Fig.11 As shown, an embodiment of the present invention further provides a battery module, comprising two busbar-free back contact battery blocks as described in the second aspect.

[0050] For the convenience of description, the two main grid-free back-contact battery blocks are respectively named as the first battery block (the upper battery block 300 in the figure) and the second battery block (the lower battery block 300 in the figure), that is, the first battery block is at the upper position in the figure, and the second battery block is at the lower position in the figure; the first battery block and the second battery block are arranged side by side along the second direction, and the m-th row of the two battery blocks 300 are close to each other for splicing, and the 1st to m-th rows of the first battery block and the second battery block are arranged in sequence from the end away from each other to the end close to each other, that is, the second battery block is equivalent to the first battery block rotated 180 degrees.

[0051] Specifically, the welding strips of opposite polarities of each two adjacent battery cell units 100 in the 1st row of the first battery block and the 1st row of the second battery block are connected by a plurality of first bus bars extending along the first direction; the welding strips of the battery cell units 100 in the mth row of the first battery block and the battery cell units 100 in the mth row of the second battery block with the same polarity are connected by the same long strip bus assembly 400; the long strip bus assembly 400 is located between the first battery block and the second battery block and serves as a welding strip lead-out structure with the same polarity.

[0052] Specifically, Fig.12 As shown, the long strip bus assembly 400 includes a plurality of second bus bars 410 ( Fig.12 It is indicated in Fig.11 ), starting from the second battery cell unit 100 in the mth row, the second bus bars 410 corresponding to every two battery cell units 100 are connected or integrally formed using a conductive member 430 ( Fig.12The second second bus bar 410 and the third second bus bar 410 are connected by a conductive member 430, and the second bus bars 410 corresponding to the other adjacent battery cell units 100 are fixedly connected by a second insulating connector 420 ( Fig.12 The first second bus bar 410 and the second second bus bar 410 are connected by a second insulating connector 420, and the second bus bars 410 corresponding to the first column and the nth column of battery cell units 100 are respectively led out as the entire positive electrode and negative electrode.

[0053] by Fig.11 For example, Fig.11 Each battery block 300 includes 11 transverse battery strings 100a, which are arranged in sequence along the second direction, and each battery string 100a includes 6 battery cell units 100 arranged along the first direction. Fig.11 The first row of battery string 100a of the second battery block is located at the top Fig.11 The mth (m=11)th row of battery strings 100a of the first battery block and the mth (m=11)th row of battery strings 100a of the second battery block are located at Fig.11 The middle position of the two is connected in parallel through a long strip bus assembly 400.

[0054] Optionally, continue to Fig.13 The second bus bar 410 includes a second support bar 411 and a plurality of second connecting pieces 412 fixed on the second support bar 411 . The second support bar 411 is a long strip structure extending along the first direction.

[0055] Multiple second connecting plates 412 are arranged at intervals along the length direction of the second support bar 411, and the length direction of the second connecting plates 412 is perpendicular to the length direction of the second support bar 411, and are used to connect the welding strips of the same polarity of the first battery block and the second battery block in parallel or to connect the welding strips of different polarities in series.

[0056] The fourth aspect, such as Fig.14 As shown, an embodiment of the present invention further provides a method for preparing a battery module, which is used to prepare the battery module as in the third aspect, and the preparation method comprises the following steps: S100, pre-prepare a solder paste layer at a preset position of the fine grid electrode layer on the back side of the battery cell unit 100 on which the fine grid electrode layer and the insulating glue layer 132 have been prepared; the fine grid electrode layer includes a plurality of positive electrode fine grids 140 and a plurality of negative electrode fine grids 150 alternately arranged along the second direction.

[0057] S200 , preparing an adhesive layer 133 on the insulating adhesive layer 132 of the battery cell unit 100 , and curing and forming the adhesive layer 133 .

[0058] S300, prefabricate the positive electrode solder strip 121 and the negative electrode solder strip 122, and place the positive electrode solder strip 121 and the negative electrode solder strip 122 alternately and spaced apart at preset positions on the fine gate electrode layer along a first direction, and contact with the corresponding solder paste layer and the adhesive layer 133; wherein the second direction is perpendicular to the first direction.

[0059] S400, arrange the battery cell units 100 obtained in S300 in the form of m rows × n columns, and from the 1st row or the mth row, sequentially connect the positive electrode welding strips 121 and the negative electrode welding strips 122 of the battery cell units 100 in two adjacent rows one by one through the strip connection assembly 200, so as to form a main grid-free back contact battery block.

[0060] S500, a plurality of first bus bars are arranged outside the first row of the busbar-free back contact battery blocks, and welding strips of different polarities of each two adjacent battery cell units 100 in the first row are connected in series or welding strips of the same polarity are connected in parallel through the first bus bars.

[0061] S600, place two identical busbar-free back-contact battery blocks without one end of the first bus bar side by side, and connect them in series or in parallel through a long strip bus assembly 400, and make the long strip bus assembly 400 connect every two battery cell units 100 in series starting from the second battery cell unit 100 in the mth row of each busbar-free back-contact battery block.

[0062] Optionally, in step S400, the first connecting piece 212 of the strip connection assembly 200 is directly connected to the corresponding soldering strip by soldering.

[0063] Optionally, in step S600, the second connecting piece of the long strip busbar assembly 400 is directly connected to the corresponding soldering strip by soldering.

[0064] Compared with the prior art, which uses glue dispenser on the back of the battery or applies the glue layer to the welding strip, the defects are that welding is performed first, glue is dispensed, and then solidified, the process is more complicated, and the tensile performance is unstable. The present invention sets the adhesive layer on the insulating adhesive layer 132, which can complete the fixed connection between the adhesive layer and the welding strip during the series welding process; and the welding strip is in series welding; at the same time, since the material surface energy of the insulating adhesive layer 132 and the material surface energy of the adhesive layer 133 differ by less than 20mN / m, and the material surface energy of the insulating adhesive layer 132 is less than the material surface energy of the adhesive layer 133, the tensile force of the welding strip can be effectively increased.

[0065] After the battery string 100a is connected in series by welding in the second direction, the prior art needs to arrange the battery string 100a for secondary connection and converge the battery cells. In addition, the spacing between the battery cell units 100 along the first direction cannot be too small. Because the battery cells on the battery string 100a are only connected by welding strips and cannot be fixed in position, the battery cell units 100 may contact the electrodes of adjacent battery cell units 100 during the secondary arrangement or subsequent transfer process, causing short circuits and other defects. The present invention uses the strip connection component 200 to weld the welding strips of the same polarity on the entire battery cell unit 100 in parallel, and then connects them in series and parallel with the adjacent battery cell units 100 in the second direction according to the component electrical connection design, and at the same time plays a role in current conduction. If a single point or a single strip of welding strip on the battery cell unit 100 fails, the strip connection component 200 can play a role in uniformly reinforcing the current collection of the battery cell unit 100, and minimize the loss caused by the failure of the welding point of the welding rod. By connecting with the strip connection component 200, the layout can be completed directly during the welding process without the need for secondary layout, which can effectively improve the production efficiency, and the battery cell units 100 can be set with zero spacing or very small spacing, or even stacked connections can be performed; the effective power generation area can be increased, and the battery power density can be improved.

[0066] The prior art requires that the battery string 100a be fixed in position with tape after secondary arrangement before lamination can be performed, otherwise the battery cell unit 100 may shift during the movement process, causing defects; the present invention uses a strip connection component 200 to simultaneously complete the layout and fixation of the entire battery module during the welding process of the welding strip, that is, the strip connection component 200 is used as a metal conductor and can also fix the battery cell unit 100 and the battery string 100a, eliminating the battery string 100a arrangement and tape fixing steps, further improving production efficiency.

[0067] It should be noted that secondary cell arrangement means that conventional cells must first be arranged in longitudinal battery strings for a single cell arrangement and string welding, and then a secondary cell arrangement is performed according to the battery assembly layout (i.e. the battery strings are arranged according to the layout) and then welded and merged as shown in the figure below. The present invention can be welded uniformly after a single cell arrangement, or the layout of the battery cells is fixed while the cell arrangement and welding is completed according to the battery assembly layout, without the need for secondary cell arrangement like conventional packaging methods.

[0068] Example 1 The battery cell unit 100 provided in the embodiment of the present invention comprises: a battery substrate 110, and a fine grid electrode layer and a welding strip layer sequentially arranged on the back side of the battery substrate 110; The fine grid electrode layer includes a plurality of positive electrode fine grids 140 and a plurality of negative electrode fine grids 150 arranged alternately at intervals along the second direction; the welding strip layer includes a plurality of positive electrode welding strips 121 and a plurality of negative electrode welding strips 122 arranged alternately at intervals along the first direction; the first direction is the horizontal direction, and the second direction is the vertical direction.

[0069] The overlapped area of ​​the positive electrode welding strip 121 and the positive electrode fine grid 140 is connected by a metal connecting layer 131, and the overlapped area of ​​the positive electrode welding strip 121 and the negative electrode fine grid 150 is connected by an insulating glue layer 132 and an adhesive layer 133, and the insulating glue layer 132 is closer to the battery substrate 110 than the adhesive layer 133; The overlapping area of ​​the negative electrode welding strip 122 and the negative electrode fine grid 150 is connected through a metal connecting layer 131, and the overlapping area of ​​the negative electrode welding strip 122 and the positive electrode fine grid 140 is connected through an insulating glue layer 132 and an adhesive layer 133; The surface energy of the insulating adhesive layer 132 material and the surface energy of the adhesive layer 133 material differ by about 15 mN / m, and the surface energy of the insulating adhesive layer 132 material is less than the surface energy of the adhesive layer 133 material. This can effectively ensure the adhesion between the adhesive layer 133 and the insulating adhesive layer 132 and the welding strip, effectively improve the tension of the welding strip, further ensure the stability of the welding of the welding strip, and improve the battery efficiency and production yield. It should be noted that the surface energy of the material in the embodiment of the present invention is measured by contact angle measurement method, and the specific measurement method refers to European standard EN828:2013.

[0070] In addition, the thickness of the insulating glue layer 132 is 20um, the thickness of the adhesive layer 133 is 30um, the size of the insulating glue layer 132 is 0.4mm×4mm, and the size of the adhesive layer 133 is 0.3mm×1.5mm. Example 1 is the optimal setting, thereby ensuring the effects of firm bonding, light transmittance, battery efficiency, etc.

[0071] In addition, an embodiment of the present invention provides a battery module prepared using battery cell units 100, in which the battery cell units 100 of the battery block 300 are arranged in 11 rows × 6 columns, the number of battery cell units 100 is 66 (i.e., the specific numbers of m and n), and the 6 battery cell units 100 in each row are electrode-welded and fixedly connected with the 6 battery cell units 100 in the next row through a strip connection assembly 200; the battery cell units 100 in each row are connected in series with the adjacent battery cell units 100 in the next row.

[0072] In addition, n battery cell units 100 arranged along the first direction form a group of battery strings 100a, and a strip connection component 200 is arranged between two adjacent battery strings 100a arranged along the second direction. The multiple first connecting pieces 212 of the strip connection component 200 directly connect the corresponding welding strips of the battery cell units 100 adjacent to each other along the second direction, and the first connecting pieces 212 partially overlap with the corresponding welding strips for lap-jointing.

[0073] Example 2 Referring to the battery cell unit 100 of Example 1, the difference is that the surface energy difference between the material of the insulating glue layer 132 and the material of the adhesive layer 133 is about 19.5 mN / m.

[0074] Example 3 Referring to the battery cell unit 100 of Example 1, the difference is that the thicknesses of the adhesive layer 133 and the insulating adhesive layer 132 are 40 um and 30 um respectively.

[0075] Example 4 Referring to the battery cell unit 100 of Example 1, the difference is that the dimensions between the adhesive layer 133 and the insulating adhesive layer 132 are 0.2 mm×1.0 mm and 0.35 mm×3 mm respectively.

[0076] Example 5 Referring to the battery cell unit 100 module of Example 1, the difference is that the battery cells of adjacent battery strings 100a are not overlapped, and the spacing between the battery cell units 100 in the first direction is 0.5 mm.

[0077] Example 6 Referring to the battery cell module of Example 1, the difference is that the number of battery cell units 100 is 6×3×2=36 (ie, m=6 and n=3).

[0078] Example 7 Referring to the battery cell module of Example 5, the difference is that the first connecting section 210 is a whole strip structure, which is used to connect the welding strips of opposite polarities of two battery cell units adjacent to each other along the second direction.

[0079] Comparative Example 1 Referring to the battery cell unit 100 of Example 1, the difference is that the battery cell unit 100 is not provided with a welding strip first, and the 11 battery cell units 100 in the first column in the vertical direction are directly connected by series welding to form a battery string 100a along the second direction, and then the battery strings 100a in the second to sixth columns are connected by series welding one by one; then the adhesive layer and the welding strip are cured and connected, and then a secondary arrangement of 6×11 is performed to form a battery block 300 arrangement, and the spacing of the battery cell units 100 in the first direction is 2mm, and then the battery string 100a is fixed by bus welding and tape to avoid displacement of the battery cell unit 100 and short circuit failure.

[0080] Comparative Example 2 Referring to the battery cell unit 100 of comparative example 1, the difference is that no adhesive layer 133 is provided on the battery cell unit 100, and after the battery string 100a is formed by serial welding, glue is dispensed on the surface of the welding strip or adhesive is applied and cured before secondary cell arrangement; the adhesive is a thermosetting adhesive.

[0081] Comparative Example 3 Referring to the battery cell unit 100 of Example 1, the difference is that the thickness of the insulating glue layer 132 is 10 um, the thickness of the adhesive layer 133 is 15 um, the size of the adhesive layer 133 is 0.3 mm×1.5 mm, and the size of the insulating glue layer 132 is 0.3 mm×1.5 mm.

[0082] Comparative Example 4 Referring to the battery cell unit 100 of Example 1, the difference is that the surface energy of the insulating glue layer 132 material and the surface energy of the adhesive layer 133 material differ by about 25 mN / m.

[0083] Comparative Example 5 Referring to the battery cell unit 100 of Example 1, the difference is that the surface energy of the insulating glue layer 132 material is smaller than the surface energy of the adhesive layer 133 material.

[0084] Test Case The performance of the battery cells obtained in the above-mentioned embodiment and comparative example was tested to obtain the relevant data in the following Table 1. (Comparison was performed with embodiment 1 as the reference 1) The specific data are as follows: Table 1 Statistics of performance indicators of different embodiments and comparative examples

[0085] It can be seen from the above results that, compared with the comparative example, the embodiment scheme of the present invention can simplify the production process, effectively increase the tension of the welding strip and reduce the pulling of the connecting welding strip when the battery block with good layout is moved during the production process, which is conducive to effectively improving the reliability of welding of the welding strip, and improving the production yield, production efficiency and battery power density. Further, according to Examples 1 and 2 to 5, it can be seen that the preferred thickness and size setting of the adhesive layer and the insulating adhesive layer 132 and the overlap connection scheme of the present invention can further coordinate and optimize the matching of various performances, and is more conducive to obtaining the best production yield, production efficiency and battery power density at the same time. Further, according to Examples 1 and 6, it can be seen that the preferred scheme of the present invention is applicable to battery cell modules of different versions. Further, according to Examples 5 and 7, it can be seen that the preferred scheme of the present invention can be applied to strip connection component structures of different shapes. Further, according to Examples 1 and 3, it can be seen that the thickness of the adhesive layer 133 and the insulating adhesive layer 132 of the preferred scheme of the present invention is conducive to taking into account both material cost and ensuring adhesion.

[0086] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A battery cell unit, characterized in that: include: A battery substrate, and a fine grid electrode layer and a welding strip layer sequentially arranged on the back side of the battery substrate; The fine grid electrode layer includes a plurality of positive fine grids and a plurality of negative fine grids arranged alternately at intervals along the second direction; the welding strip layer includes a plurality of positive welding strips and a plurality of negative welding strips arranged alternately at intervals along the first direction; the first direction is perpendicular to the second direction; The overlapped area of ​​the positive electrode welding strip and the positive electrode fine grid is connected by a metal connecting layer, and the overlapped area of ​​the positive electrode welding strip and the negative electrode fine grid is connected by an insulating glue layer and an adhesive layer, and the insulating glue layer is closer to the battery substrate than the adhesive layer; The overlapping area of ​​the negative electrode welding strip and the negative electrode fine grid is connected through a metal connecting layer, and the overlapping area of ​​the negative electrode welding strip and the positive electrode fine grid is connected through an insulating glue layer and an adhesive layer; The surface energy of the insulating glue layer material differs from the surface energy of the adhesive layer material by less than 20 mN / m, and the surface energy of the insulating glue layer material is less than the surface energy of the adhesive layer material.

2. The battery cell unit according to claim 1, characterized in that: The material of the metal connection layer is solder paste, the material of the insulating adhesive layer is one of epoxy resin-based insulating adhesive, silicone-based insulating adhesive, polyurethane-based insulating adhesive, and polyimide-based insulating adhesive, and the material of the bonding layer is UV~heat-curing dual-curing adhesive, or two-component heat-curing adhesive.

3. The battery cell unit according to claim 2, characterized in that: The dimensions of the adhesive layer include: a dimension along the first direction of 0.2-0.5 mm, a dimension along the second direction of 0.6-3 mm, and a spacing between adjacent positive electrode fine grids and negative electrode fine grids of 0.5 mm-0.8 mm.

4. A busbar-free back contact battery block, characterized in that: include: m rows×n columns of battery cell units according to any one of claims 1 to 3; wherein n battery cell units are arranged along the first direction and m battery cell units are arranged along the second direction; N battery cell units arranged along the first direction form a group of battery strings, and a strip connection component is arranged between two adjacent battery strings arranged along the second direction. The strip connection component includes a plurality of first connection segments arranged at intervals along the first direction, and the adjacent first connection segments are fixedly connected by a first insulating connector; the first connection segment is used to electrically connect the welding strips of opposite polarities of two adjacent battery cell units along the second direction.

5. The busbar-free back contact battery block according to claim 4, characterized in that: The first connecting section includes a first supporting bar and a plurality of first connecting pieces fixed on the first supporting bar, wherein the first supporting bar is a long strip structure extending along a first direction; The plurality of first connecting sheets are spaced apart along the length direction of the first supporting bar, and the length direction of the first connecting sheets is perpendicular to the length direction of the first supporting bar, and are used to respectively connect welding strips of opposite polarities of two adjacent battery cell units along the second direction.

6. The busbar-free back contact battery block according to claim 5, characterized in that: Two battery cell units adjacent to each other along the second direction are overlapped, and the connecting sheet is a step structure or a flat plate structure.

7. The busbar-free back contact battery block according to claim 4, characterized in that: The first connecting section is a whole strip structure, and is used to connect the welding strips of opposite polarities of two battery cell units adjacent to each other along the second direction.

8. A battery module, characterized in that: comprising two busbar-free back contact battery blocks according to any one of claims 4 to 7; The two busbar-free back-contact battery blocks are respectively a first battery block and a second battery block; the first battery block and the second battery block are arranged side by side along a second direction, and the m-th rows of the two battery blocks are close to each other for splicing, and the first to m-th rows of the first battery block and the second battery block are arranged in sequence from an end away from each other to an end close to each other; The welding strips of opposite polarities of each two adjacent battery cell units in the first row of the first battery block and the first row of the second battery block are connected by a plurality of first bus bars extending along the first direction; The welding strips of the same polarity of the battery cell units of the mth row of the first battery block and the battery cell units of the mth row of the second battery block are connected through the same long strip bus assembly; the long strip bus assembly is located between the first battery block and the second battery block; The long strip bus assembly includes a plurality of second bus bars arranged along the second direction. Starting from the second battery cell unit in the mth row, the second bus bars corresponding to every two battery cell units are connected by a conductive member or formed as one piece, and the second bus bars corresponding to the remaining adjacent battery cell units are fixedly connected by a second insulating connector, and the second bus bars corresponding to the battery cell units in the 1st column and the nth column are respectively led out as the entire positive and negative electrodes.

9. The battery module according to claim 8, characterized in that: The second bus bar includes a second support bar and a plurality of second connecting pieces fixed on the second support bar, wherein the second support bar is a long strip structure extending along the first direction; A plurality of second connecting plates are arranged at intervals along the length direction of the second support bar, and the length direction of the second connecting plates is perpendicular to the length direction of the second support bar, and are used to connect the welding strips of the same polarity of the first battery block and the second battery block in parallel or to connect the welding strips of different polarities in series.

10. A method for preparing a battery module, for preparing the battery module as claimed in claim 8 or 9, characterized in that: include: S100, pre-preparing a solder paste layer at a preset position of a fine grid electrode layer on the back side of a cell unit on which a fine grid electrode layer and an insulating adhesive layer have been prepared; the fine grid electrode layer comprises a plurality of positive electrode fine grids and a plurality of negative electrode fine grids alternately arranged at intervals along a second direction; S200, preparing an adhesive layer on the insulating adhesive layer of the battery cell unit, and curing and forming the adhesive layer; S300, prefabricating a positive electrode welding strip and a negative electrode welding strip, and placing the positive electrode welding strip and the negative electrode welding strip alternately and spaced at preset positions on the fine gate electrode layer along a first direction, and contacting the corresponding solder paste layer and adhesive layer; wherein the second direction is perpendicular to the first direction; S400, arranging the battery cell units obtained in S300 in a manner of m rows×n columns, and starting from the first row or the mth row, sequentially connecting the positive electrode welding strips and the negative electrode welding strips of the battery cell units in two adjacent rows one by one through a strip connection assembly, thereby forming a busbar-free back contact battery block; S500, disposing a plurality of first bus bars outside the first row of the busbar-free back-contact battery block, and connecting the welding strips of different polarities of each two adjacent battery cell units in the first row in series or connecting the welding strips of the same polarity in parallel through the first bus bars; S600, place two identical busbar-free back-contact battery blocks without one end of the first bus bar side by side, and connect them in series or in parallel through a long strip bus assembly, and make the long strip bus assembly connect every two battery cell units in series starting from the second battery cell unit in the mth row of each busbar-free back-contact battery block.

11. The method for preparing a battery module according to claim 10, characterized in that: include: In step S400, the first connecting piece of the strip connection assembly is directly connected to the corresponding soldering strip by soldering.

12. The method for preparing a battery module according to claim 10, characterized in that: include: In step S600, the second connecting piece of the long strip busbar assembly is directly connected to the corresponding soldering strip by soldering.

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