Interconnection method of main-grid-free back contact battery assembly

Abstract

The invention relates to the technical field of battery piece production, in particular to an interconnection method of a main-grid-free back contact battery assembly, which comprises the following steps of: printing insulating glue on a positive electrode fine grid line or a negative electrode fine grid line; the battery piece printed with the insulation paste is dried; printing conductive adhesive on the fine grid lines which are not printed with the insulating adhesive, wherein the conductive adhesive is composed of a weld-aid part and a conductive connecting part; laying a welding strip on the battery piece, and pressing the welding strip on the conductive adhesive; the conductive adhesive is dried for preliminary curing, and the welding strip is pre-fixed on the battery piece; and then carrying out lamination welding treatment to realize alloying connection between the welding strip and the fine grid line. According to the invention, the conductive adhesive composed of the welding aid part and the conductive connecting part is used together with the insulating adhesive, so that the problem that the battery piece needs to be baked for multiple times when the traditional solder paste / insulating adhesive / curing adhesive is combined for use is solved, the process is simplified, the warping condition of the battery piece is reduced, the yield of the battery piece is ensured, and the quality of the battery piece is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of battery cell production, and in particular to an interconnection method for busbar-free back-contact battery components. Background Art

[0002] Solar energy is a green and efficient energy source, an important part of renewable resources, and an important part of the sustainable development strategy implemented by governments in terms of resource utilization. In solar energy applications, photovoltaic power generation, as an important application mode, has gradually been widely used due to its advantages such as no noise, maintenance-free, and no emissions. Crystalline silicon solar cells dominate the field of photovoltaic power generation, mainly due to the abundant reserves of silicon materials in the earth's crust, relatively mature photovoltaic power generation technology, and low cost.

[0003] At present, the main busbar-free back contact battery modules in the photovoltaic industry mainly adopt the lamination welding battery cell interconnection method, which can be referred to in the attached Figure 1-3 . That is, first print solder paste, insulating glue, and curing glue on the battery cell in sequence, then lay the solder tape on the battery cell for pre-fixation, and complete the soldering of the solder tape and the fine grid during the lamination process. Among them, the role of the insulating glue is to prevent the solder tape from directly contacting the fine grid line of opposite polarity to cause a short circuit; the role of the solder paste is to increase the height of the welding part, thereby assisting welding; the role of the curing glue is to pre-fix the solder tape to prevent it from shifting during lamination. The specific steps are: near the position where the fine grid of the battery cell contacts the solder tape (welding part), print the insulating glue on the fine grid line of opposite polarity, and dry it. Then, print the solder paste on the welding part and dry it again. Finally, print the curing glue with a certain gap at the position where the solder tape contacts the battery cell, then lay the solder tape on the battery cell, heat and dry the battery string, and then stack them together in the order of glass, film, battery string, film, and backplane, and send them to the laminator for lamination, thereby completing the interconnection welding of the main grid-free back contact component.

[0004] The disadvantages of the above interconnection method are low yield and poor reliability. Since the battery cell needs to be repeatedly printed and dried three times, the process is relatively complicated, and the battery cell undergoes three hot and cold cycles, which will cause the battery cell to warp, affecting the mechanical strength of the battery cell, thereby causing the yield of the battery module to decrease. In addition, since the battery cell no longer has a main grid, the welding ribbon can only collect current through the fine grid, and the fine grid is small in width. The welding ribbon welded thereon frequently applies shear stress to the fine grid due to thermal expansion and contraction during the outdoor hot and cold cycle. The fine grid is prone to breakage under the action of this stress, resulting in the inability to collect the current of the entire fine grid, which seriously affects the power generation performance of the battery module and causes the reliability of the battery module to be unable to be guaranteed. Based on this, a method for interconnecting a battery module without a main grid back contact is proposed. Summary of the invention

[0005] In order to address the deficiencies of the prior art, the present invention provides an interconnection method for a main grid-free back contact battery assembly, which uses a conductive adhesive composed of a soldering part and a conductive connecting part in conjunction with an insulating adhesive, thereby simplifying the process and ensuring the quality of the battery cells.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for interconnecting a busbar-free back contact battery assembly, comprising the following steps:

[0007] (1) Printing insulating glue on the positive electrode fine grid line or the negative electrode fine grid line, and the insulating glue is arranged in the same straight line;

[0008] (2) Drying the battery cell printed with insulating glue;

[0009] (3) Printing conductive glue on the fine grid line where no insulating glue is printed, the conductive glue consists of a soldering part and a conductive connection part, and the conductive glue and the insulating glue are also arranged in the same straight line;

[0010] (4) Lay the soldering tape on the battery cell and press the soldering tape onto the conductive adhesive;

[0011] (5) Drying the conductive adhesive for preliminary curing and pre-fixing the soldering tape on the battery cell;

[0012] (6) A lamination welding process is then performed to achieve alloy connection between the welding strip and the fine grid line.

[0013] Preferably, in step (1), the height of the insulating glue is 10-50 μm, and its resistivity is ≥ 1×10 14 Ω·cm.

[0014] Preferably, in step (3), the conductive glue is silver powder conductive glue, carbon powder conductive glue or aluminum powder conductive glue; its height is 25-60 μm, and its resistivity is ≤1×10 -5 Ω·cm, tensile strength ≥10MPa, peel strength ≥0.5N / cm.

[0015] Preferably, in step (3), the soldering portion is a solid circle, and its diameter is 0.5-0.8 times the width of the soldering strip.

[0016] Preferably, in step (3), the conductive connecting portion is a hollow rectangle, the length of the hollow rectangle is 1.2-1.8 times the width of the solder strip, the width is 0.5-2 times the spacing between adjacent fine grid lines, and the width of the edge is 25-100 μm.

[0017] Preferably, in step (3), the conductive connection portion is a hollow triangle, the side length of the hollow triangle is 1.2-1.8 times the width of the solder strip, the height is 0.5-2 times the spacing between adjacent fine grid lines, and the side width is 25-100 μm.

[0018] Preferably, in step (3), the conductive connecting portion is a hollow circular ring, the diameter of the hollow circular ring is 1.2-1.8 times the width of the welding strip, and the width of the edge is 25-100 μm.

[0019] Preferably, in step (6), the lamination welding temperature is 130-150° C., and the lamination welding time is 5-15 min.

[0020] The present invention provides a method for interconnecting a busbar-free back contact battery assembly, which has the following beneficial effects compared with the prior art:

[0021] The present invention adopts a conductive adhesive composed of a soldering part and a conductive connecting part, which is used together with an insulating adhesive, thereby reducing the problem of multiple baking of battery cells required when using a traditional combination of solder paste / insulating adhesive / curing adhesive, simplifying the process, reducing the warping of the battery cells, and ensuring the yield of the battery cells.

[0022] The present invention constructs a connected conductive connection part on the periphery of the soldering part. Even if the thin grid line is broken at the position of the soldering part, the current will be collected through the conductive connection part, thereby ensuring the quality of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0024] Figure 1 It is a schematic diagram of the distribution of insulating glue, curing glue and solder paste in the prior art;

[0025] Figure 2 A schematic diagram of battery cell series welding in the prior art;

[0026] Figure 3 It is a flow chart of interconnection of main grid-free back contact battery components in the prior art;

[0027] Figure 4 This is a schematic diagram of the distribution of the conductive adhesive and the insulating adhesive in the present invention;

[0028] Figure 5 This is a schematic diagram of the battery cell series welding in the present invention;

[0029] Figure 6 It is a schematic diagram of the structure of the soldering part and the hollow rectangular conductive connecting part in the present invention;

[0030] Figure 7 It is a schematic diagram of the structure of the soldering part and the hollow triangle conductive connecting part in the present invention;

[0031] Figure 8 It is a schematic diagram of the structure of the soldering part and the hollow circular conductive connecting part in the present invention;

[0032] Fig. 9 This is a flow chart of interconnection of main-grid-free back-contact battery components in the present invention. DETAILED DESCRIPTION

[0033] The following examples are used to explain the implementation methods of the present application in detail, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0034] Example 1

[0035] A method for interconnecting a busbar-free back contact battery assembly comprises the following steps:

[0036] (1) Print insulating glue on the positive electrode fine grid line. The height of the insulating glue is 10μm and its resistivity is ≥1×10 14 Ω·cm, the insulating glue is arranged in the same straight line.

[0037] (2) Drying the battery cell printed with insulating glue.

[0038] (3) Print carbon powder conductive glue on the fine grid lines (negative fine grid lines) without printed insulating glue, with a height of 25 μm and a resistivity of ≤1×10 -5 Ω·cm, tensile strength ≥10MPa, peel strength ≥0.5N / cm, the conductive adhesive consists of a soldering part and a conductive connecting part, and the conductive adhesive and the insulating adhesive are also arranged in the same straight line;

[0039] The soldering part is a solid circle, and its diameter is 0.8 times the width of the soldering strip. The conductive connection part is a hollow rectangle, and its length is 1.2 times the width of the soldering strip, its width is 2 times the spacing between adjacent fine grid lines, and its edge width is 25 μm.

[0040] (4) Lay the solder tape on the battery cell and press the solder tape onto the conductive adhesive.

[0041] (5) Dry the conductive adhesive for preliminary curing and pre-fix the soldering tape on the battery cell.

[0042] (6) Subsequently, a lamination welding process is performed at 150° C. for 5 minutes to achieve alloy connection between the welding strip and the fine grid line.

[0043] Example 2

[0044] A method for interconnecting a busbar-free back contact battery assembly comprises the following steps:

[0045] (1) Print insulating glue on the negative electrode fine grid line. The height of the insulating glue is 50 μm and its resistivity is ≥ 1×10 14 Ω·cm, the insulating glue is arranged in the same straight line.

[0046] (2) Drying the battery cell printed with insulating glue.

[0047] (3) Print aluminum powder conductive glue on the fine grid lines (positive fine grid lines) without printed insulating glue, with a height of 60 μm and a resistivity of ≤1×10 -5 Ω·cm, tensile strength ≥10MPa, peel strength ≥0.5N / cm, the conductive adhesive consists of a soldering part and a conductive connecting part, and the conductive adhesive and the insulating adhesive are also arranged in the same straight line;

[0048] The soldering part is a solid circle, and its diameter is 0.5 times the width of the soldering strip. The conductive connection part is a hollow rectangle, and its length is 1.8 times the width of the soldering strip, its width is 0.5 times the spacing between adjacent fine grid lines, and its edge width is 100 μm.

[0049] (4) Lay the solder tape on the battery cell and press the solder tape onto the conductive adhesive.

[0050] (5) Dry the conductive adhesive for preliminary curing and pre-fix the soldering tape on the battery cell.

[0051] (6) Subsequently, a lamination welding process is performed at 130° C. for 15 minutes to achieve alloy connection between the welding strip and the fine grid line.

[0052] Example 3

[0053] A method for interconnecting a busbar-free back contact battery assembly comprises the following steps:

[0054] (1) Print insulating glue on the positive electrode fine grid line. The height of the insulating glue is 30μm and its resistivity is ≥1×10 14 Ω·cm, the insulating glue is arranged in the same straight line.

[0055] (2) Drying the battery cell printed with insulating glue.

[0056] (3) Print silver powder conductive glue on the fine grid lines (negative fine grid lines) without printed insulating glue, with a height of 42 μm and a resistivity of ≤1×10 -5 Ω·cm, tensile strength ≥10MPa, peel strength ≥0.5N / cm, the conductive adhesive consists of a soldering part and a conductive connecting part, and the conductive adhesive and the insulating adhesive are also arranged in the same straight line;

[0057] The soldering part is a solid circle, and its diameter is 0.6 times the width of the soldering strip. The conductive connection part is a hollow rectangle, and its length is 1.5 times the width of the soldering strip, its width is 1.2 times the spacing between adjacent fine grid lines, and its edge width is 50 μm.

[0058] (4) Lay the solder tape on the battery cell and press the solder tape onto the conductive adhesive.

[0059] (5) Dry the conductive adhesive for preliminary curing and pre-fix the soldering tape on the battery cell.

[0060] (6) Subsequently, a lamination welding process is performed at 140° C. for 10 minutes to achieve alloy connection between the welding strip and the fine grid line.

[0061] Example 4

[0062] A method for interconnecting a busbar-free back contact battery assembly is basically the same as that of Example 3, except that:

[0063] In step (3), the conductive connection portion is a hollow triangle, the side length of the hollow triangle is 1.5 times the width of the solder strip, the height is 1.2 times the spacing between adjacent fine grid lines, and the side width is 50 μm.

[0064] Example 5

[0065] A method for interconnecting a main grid-free back contact battery assembly is basically the same as Example 4, except that the side length of the hollow triangle is 1.2 times the width of the welding strip, the height is 0.5 times the spacing between adjacent fine grid lines, and the side width is 25μm.

[0066] Example 6

[0067] A method for interconnecting a main grid-free back contact battery assembly is basically the same as Example 4, except that the side length of the hollow triangle is 1.8 times the width of the welding strip, the height is 1.9 times the spacing between adjacent fine grid lines, and the side width is 100 μm.

[0068] Example 7

[0069] A method for interconnecting a busbar-free back contact battery assembly is basically the same as that of Example 3, except that:

[0070] In step (3), the conductive connecting portion is a hollow circular ring, the diameter of the hollow circular ring is 1.5 times the width of the solder strip, and the width of the edge is 50 μm.

[0071] Example 8

[0072] A method for interconnecting a main-grid-free back-contact battery assembly is basically the same as Example 7, except that the diameter of the hollow circular ring is 1.2 times the width of the welding strip, and the width of the edge is 25 μm.

[0073] Example 9

[0074] A method for interconnecting a main-grid-free back-contact battery assembly is basically the same as Example 7, except that the diameter of the hollow circular ring is 1.8 times the width of the welding strip, and the width of the edge is 100 μm.

[0075] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for interconnecting a busbar-free back contact battery assembly, characterized in that: The following steps are involved: (1) Printing insulating glue on the positive electrode fine grid line or the negative electrode fine grid line, and the insulating glue is arranged in the same straight line; (2) Drying the battery cell printed with insulating glue; (3) Printing conductive glue on the fine grid line where no insulating glue is printed, the conductive glue consists of a soldering part and a conductive connection part, and the conductive glue and the insulating glue are also arranged in the same straight line; (4) Lay the soldering tape on the battery cell and press the soldering tape onto the conductive adhesive; (5) Drying the conductive adhesive for preliminary curing and pre-fixing the soldering tape on the battery cell; (6) A lamination welding process is then performed to achieve alloy connection between the welding strip and the fine grid line.

2. The interconnection method of busbar-free back contact battery assembly according to claim 1, characterized in that: In step (1), the height of the insulating glue is 10-50 μm, and its resistivity is ≥ 1×10 14 Ω·cm.

3. The interconnection method of busbar-free back contact battery assembly according to claim 1, characterized in that: In step (3), the conductive glue is silver powder conductive glue, carbon powder conductive glue or aluminum powder conductive glue; its height is 25-60 μm, and its resistivity is ≤1×10 -5 Ω·cm, tensile strength ≥10MPa, peel strength ≥0.5N / cm.

4. The interconnection method of busbar-free back contact battery assembly according to claim 1, characterized in that: In step (3), the soldering portion is a solid circle, and its diameter is 0.5-0.8 times the width of the soldering strip.

5. The interconnection method of busbar-free back contact battery assembly according to claim 1, characterized in that: In step (3), the conductive connection portion is a hollow rectangle, the length of the hollow rectangle is 1.2-1.8 times the width of the solder strip, the width is 0.5-2 times the spacing between adjacent fine grid lines, and the width of the edge is 25-100 μm.

6. The interconnection method of busbar-free back contact battery assembly according to claim 1, characterized in that: In step (3), the conductive connection portion is a hollow triangle, the side length of the hollow triangle is 1.2-1.8 times the width of the solder strip, the height is 0.5-2 times the spacing between adjacent fine grid lines, and the side width is 25-100 μm.

7. The interconnection method of busbar-free back contact battery assembly according to claim 1, characterized in that: In step (3), the conductive connecting portion is a hollow circular ring, the diameter of the hollow circular ring is 1.2-1.8 times the width of the solder strip, and the width of the edge is 25-100 μm.

8. The interconnection method of busbar-free back contact battery assembly according to claim 1, characterized in that: In step (6), the lamination welding temperature is 130-150° C., and the lamination welding time is 5-15 minutes.

Images