Battery piece assembly and preparation method thereof

Abstract

The invention relates to the technical field of photovoltaic equipment, in particular to a battery piece assembly and a preparation method thereof. The battery piece assembly comprises a plurality of back contact battery pieces and at least one connecting piece, wherein the plurality of back contact battery pieces are arranged in sequence; each back contact battery piece is connected with a plurality of welding strips, and the plurality of welding strips are arranged at intervals along the length direction of the back contact battery piece; the connecting piece comprises a flexible insulating layer, a plurality of conductive layers and a plurality of connecting layers which are arranged in sequence; the plurality of conductive layers are arranged at intervals along the length direction of the flexible insulating layer and are connected to the same side of the flexible insulating layer; each conductive layer is connected with at least one connecting layer; wherein each conductive layer corresponds to two welding strips which are respectively positioned on two adjacent back contact battery pieces; and the connecting layer on each conductive layer is connected with two corresponding welding strips. According to the battery piece assembly, the deformation resistance of the back contact battery can be improved, and the connection stability can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic equipment, and in particular to a cell assembly and a preparation method thereof. Background Art

[0002] With the continuous advancement of photovoltaic technology, back-contact cells (BCs) have become a key research topic in the field. By moving all electrodes to the back of the cell, BCs effectively reduce light obstruction by the front-side soldering ribbon, significantly improving photoelectric conversion efficiency.

[0003] However, the back-contact battery in the prior art has problems of poor deformation resistance and unstable connection. Summary of the Invention

[0004] The purpose of the present invention includes providing a battery cell assembly and a preparation method thereof, which can improve the deformation resistance of the back contact battery and improve the stability of the connection.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a battery cell assembly, comprising:

[0007] Multiple back-contact battery cells are arranged in sequence; each back-contact battery cell is connected to multiple welding strips, and the multiple welding strips are spaced apart along the length direction of the back-contact battery cell;

[0008] At least one connector, the connector comprising a flexible insulating layer, a plurality of conductive layers, and a plurality of connecting layers arranged in sequence; the plurality of conductive layers are spaced apart along the length of the flexible insulating layer and connected to the same side of the flexible insulating layer; each conductive layer is connected to at least one connecting layer;

[0009] Wherein, each conductive layer corresponds to two welding strips respectively located on two adjacent back-contact solar cells; and the connection layer on each conductive layer is connected to the corresponding two welding strips.

[0010] In an optional embodiment, the plurality of welding strips include a plurality of positive electrode welding strips and a plurality of negative electrode welding strips, and the plurality of positive electrode welding strips and the plurality of negative electrode welding strips are alternately arranged;

[0011] The multiple positive electrode welding strips of one back contact battery cell correspond one to one with the multiple negative electrode welding strips of another back contact battery cell;

[0012] A positive electrode welding strip and a corresponding negative electrode welding strip are connected to a connection layer on the same conductive layer.

[0013] In an optional embodiment, each conductive layer is connected to two connection layers, and the two connection layers are arranged at intervals; the two connection layers are respectively connected to a corresponding positive electrode welding strip and a negative electrode welding strip.

[0014] In an optional embodiment, the connection layer is made of a low-melting-point solder material and is formed by pressing after the soldering strip is attached.

[0015] In an optional embodiment, the thickness of the conductive layer at both ends is greater than the thickness of the middle portion of the conductive layer.

[0016] In an optional embodiment, the battery cell assembly further includes two adhesive films and two laminates, and the back-contact battery cell and the connector are both located between the two laminates and in contact with the laminates;

[0017] Each adhesive film is located between a laminate and a back-contact battery sheet and is used to fill the gap between two adjacent conductive layers.

[0018] In an alternative embodiment, the width of the conductive layer is less than or equal to the width of the flexible insulating layer.

[0019] In a second aspect, the present invention provides a method for preparing a battery cell assembly according to any one of the aforementioned embodiments, the method comprising:

[0020] Providing a plurality of back-contact battery cells, and arranging the plurality of back-contact battery cells in sequence;

[0021] Connecting multiple positive electrode welding ribbons and multiple negative electrode welding ribbons alternately and at intervals to the surface of the back contact battery sheet;

[0022] Providing at least one connector so that each of two adjacent back-contact battery sheets is equipped with one connector;

[0023] Two adjacent back-contact battery cells are connected in series using a connector, so that each connection layer is connected to a positive electrode welding ribbon and / or a negative electrode welding ribbon.

[0024] In an optional embodiment, after the step of connecting two adjacent back-contact battery cells in series using a connector, the preparation method further comprises:

[0025] Two laminates and two adhesive films are provided;

[0026] Lay two adhesive films on both sides of the back contact solar cell;

[0027] The back contact cell and the connector are pressed by two laminates, so that during the pressing process, the low melting point material gradually forms a connecting layer.

[0028] In an optional embodiment, the step of providing at least one connector includes:

[0029] Lay low melting point material at each welding strip;

[0030] Placing a plurality of metal blocks correspondingly above the plurality of welding strips, and making the metal blocks contact with the low melting point material;

[0031] The polyimide film is laid on the plurality of metal blocks so that the polyimide film covers the plurality of metal blocks.

[0032] The advantageous effects of the battery cell assembly and the preparation method thereof provided by the embodiments of the present invention include:

[0033] This cell assembly can connect the grid lines on two adjacent back-contact cells via a connecting layer, thereby enabling electrical conduction between the two back-contact cells using the conductive layer. By providing a flexible insulating layer, the cell assembly utilizes the elastic deformation properties of the flexible insulating layer to provide deformation space, thereby preventing the soldering ribbon from detaching due to relative displacement between the two back-contact cells during the connection process. Furthermore, this embodiment prevents the soldering ribbon from shifting or twisting due to the flow path of the adhesive film during the lamination process, thereby improving the cell assembly's deformation resistance, connection stability, and aesthetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 A schematic structural diagram of the battery cell assembly provided in this embodiment from a first viewing angle;

[0036] Figure 2 A schematic structural diagram of a connector provided in this embodiment;

[0037] Figure 3 for Figure 2 A partial enlarged view of point A in the middle;

[0038] Figure 4 A partial schematic diagram of the battery cell assembly provided in this embodiment from a second viewing angle;

[0039] Figure 5 A partial schematic diagram of another connecting member provided in this embodiment;

[0040] Figure 6 A partial schematic diagram of another connecting member provided in this embodiment;

[0041] Figure 7A schematic flow chart of the method for preparing a battery cell assembly provided in this embodiment.

[0042] Icon: 100-battery cell assembly; 110-back contact battery cell; 120-connector; 121-flexible insulation layer; 122-conductive layer; 123-connection layer; 130-positive electrode welding strip; 140-negative electrode welding strip. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0045] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0046] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does 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, it should not be understood as a limitation on the present invention.

[0047] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0048] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0049] In the prior art, back-contact solar cells are commonly connected using solder ribbons, with multiple cells connected in series via the ribbons to form a battery string. However, solder ribbon connections are rigid, and while they can achieve a certain degree of electrical connection between cells, they suffer from poor deformation resistance.

[0050] During the lamination and heating process of photovoltaic modules, the adhesive film melts and becomes fluid. This fluidity can cause the soldering ribbons to shift or twist, affecting the position of the cells. Furthermore, forces between the cells can amplify these displacements, affecting the appearance consistency of the module.

[0051] More seriously, the movement of the cell can cause the connection between the solder ribbon and the cell to become loose, resulting in a cold solder joint and affecting the electrical performance of the module. If the offset is large, it can also cause contact between adjacent cells, leading to a short circuit in the entire battery string. These problems not only reduce the reliability of the module but also increase the difficulty of quality control during the production process. Therefore, the existing solder ribbon connection method has obvious limitations in the application of back-contact cells.

[0052] Based on the above questions, please refer to Figure 1-Figure 4 An embodiment of the present invention provides a battery cell assembly 100 . In this embodiment, the battery cell assembly 100 includes two back-contact battery cells 110 and a connector 120 . The two back-contact battery cells 110 are connected together via the connector 120 .

[0053] In other embodiments, the battery cell assembly 100 may further include a larger number of back-contact battery cells 110. The multiple back-contact battery cells 110 are arranged sequentially, and a connector 120 is configured for every two adjacent back-contact battery cells 110. The multiple back-contact battery cells 110 are sequentially connected together using the connectors 120. Therefore, in other embodiments, the number of connectors 120 is also multiple.

[0054] In this embodiment, the connector 120 includes a flexible insulating layer 121 , multiple conductive layers 122 , and multiple connecting layers 123 connected in sequence along a vertical direction; each conductive layer 122 is connected to the same side of the flexible insulating layer 121 and is connected to a connecting layer 123 .

[0055] Specifically, in this embodiment, the number of conductive layers 122 is equal to the number of soldering strips on a back-contact battery cell 110, that is, each conductive layer 122 corresponds to a soldering strip on a back-contact battery cell 110. Since the connector 120 is used to connect two adjacent back-contact battery cells 110, one conductive layer 122 corresponds to two soldering strips located on two adjacent back-contact battery cells 110. The two soldering strips are connected to the connecting layer 123 on the corresponding conductive layer 122, so that the two soldering strips can be connected to the corresponding conductive layer 122 through the connecting layer 123 and conduct electricity.

[0056] Since each conductive layer 122 in this embodiment is connected to a connection layer 123 , each connection layer 123 corresponds to two welding strips respectively located on two adjacent back-contact battery cells 110 , and each connection layer 123 is connected to the corresponding two welding strips.

[0057] For other embodiments, please refer to Figure 1 and Figure 5 Each conductive layer 122 may also be connected to two spaced-apart connection layers 123. Since one conductive layer 122 corresponds to two solder strips located on two adjacent back-contact battery cells 110, one connection layer 123 on each conductive layer 122 corresponds to a solder strip of one back-contact battery cell 110, and the other connection layer 123 corresponds to a solder strip of another back-contact battery cell 110. Therefore, in other embodiments, each connection layer 123 is connected to a corresponding solder strip.

[0058] It can be understood that since the multiple conductive layers 122 are arranged at intervals along the length direction of the flexible insulating layer 121, each back-contact battery cell 110 is connected to multiple welding strips arranged at intervals along its length direction; in addition, each welding strip is connected to the connecting layer 123 on the corresponding conductive layer 122; therefore, the length direction of the flexible insulating layer 121 is parallel to the length direction of the back-contact battery cell 110.

[0059] It should be noted that the flexible insulating layer 121 in this embodiment is made of flexible material, thereby utilizing the elastic deformation characteristics of the flexible material itself to provide deformation space for the battery cell assembly 100, so that during the lamination and heating process, the flexible insulating layer 121 can buffer the pressure applied by the laminate through its own deformation to reduce the pressure applied to the back-contact battery cell 110, thereby avoiding the movement of the back-contact battery cell 110 and avoiding affecting the conductive efficiency of the battery cell assembly 100 and the appearance of the battery cell assembly 100.

[0060] Moreover, this embodiment can also provide deformation space for relative movement of the two back-contact battery cells 110, so that during the process of connecting the two back-contact battery cells 110, even if the two back-contact battery cells 110 are caused to move relative to each other due to the force between the two back-contact battery cells 110, the soldering ribbon will not be offset or twisted, thereby avoiding the phenomenon of cold soldering and improving the conductive efficiency.

[0061] Furthermore, the plurality of welding ribbons in this embodiment are divided into a plurality of positive electrode welding ribbons 130 and a plurality of negative electrode welding ribbons 140 , and the plurality of positive electrode welding ribbons 130 and the plurality of negative electrode welding ribbons 140 are alternately arranged on the back contact battery cell 110 .

[0062] It can be understood that since the number of conductive layers 122 is equal to the number of solder strips on a back-contact battery cell 110 , the sum of the number of positive solder strips 130 and negative solder strips 140 on a back-contact battery cell 110 is equal to the number of conductive layers 122 .

[0063] In order to connect two adjacent back-contact battery cells 110 in series, each conductive layer 122 needs to be electrically connected to a positive electrode welding ribbon 130 and a negative electrode welding ribbon 140. Therefore, the number of positive electrode welding ribbons 130 in one back-contact battery cell 110 is equal to the number of negative electrode welding ribbons 140 in the other back-contact battery cell 110.

[0064] In this embodiment, each conductive layer 122 is connected to a connecting layer 123 , so the connecting layer 123 is connected to the positive electrode welding ribbon 130 and the negative electrode welding ribbon 140 .

[0065] In other embodiments, each conductive layer 122 is connected to two connection layers 123 , so one connection layer 123 is connected to the positive electrode welding ribbon 130 , and the other connection layer 123 is connected to the negative electrode welding ribbon 140 .

[0066] In other embodiments, multiple back-contact battery cells 110 can be connected in parallel. In this case, each conductive layer 122 needs to be connected to two positive electrode welding strips 130 or two negative electrode welding strips 140. Therefore, the connecting layer 123 is connected to the two positive electrode welding strips 130 or the two negative electrode welding strips 140.

[0067] Furthermore, in this embodiment, the connection layer 123 is made of a low-melting-point solder material, which is applied to the conductive layer 122. Subsequently, when the connector 120 is used to connect two adjacent back-contact battery cells 110, the low-melting-point solder material is bonded to the solder ribbon on the back-contact battery cells 110. During the lamination heating process, the low-melting-point solder material is heated to a molten state and wraps around the solder ribbon. After lamination is completed, it cools to form the connection layer 123, connecting the solder ribbon and achieving electrical continuity between the solder ribbon and the conductive layer 122.

[0068] It is understandable that before lamination, a structural member made of a low-melting-point welding material may be placed on the conductive layer 122 so that the structural member abuts against the welding ribbon, thereby forming the connection layer 123 after lamination and heating.

[0069] For example, a welding sheet made of a low-melting-point welding material can be provided, and the welding sheet can be provided on the conductive layer 122, and the welding sheet can be abutted against the welding strip, so that during the lamination process, the welding sheet is melted to form a connecting layer 123, connecting the conductive layer 122 and the welding strip together and conducting.

[0070] According to the above content, in order to facilitate deformation, please refer to Figure 1 and Figure 6 In this embodiment, the conductive layer 122 can be configured to be thicker at both ends and thinner in the middle, meaning the thickness of the conductive layer 122 at both ends is greater than the thickness in the middle. The structural member made of a low-melting-point solder material may have a protrusion in the middle. During the lamination and heating process, the conductive layer 122 is heated, and the protrusion compresses the conductive layer 122, causing it to deform. The compressed portion flows toward the ends, thereby increasing the contact area between the conductive layer 122, the solder ribbon, and the connecting layer 123, improving the stability of the connection and preventing the solder ribbon from deflecting and twisting during the lamination process. Furthermore, this can disperse stress, preventing stress concentration that could affect the durability and fatigue resistance of the conductive layer 122, thereby increasing the service life of the battery cell assembly 100. The thinning of the middle portion reduces resistance and improves conductivity efficiency.

[0071] Furthermore, this embodiment includes two adhesive films and two laminates. The back-contact cell 110 and connector 120 are located between the two laminates and in contact with them. Each adhesive film is located between one laminate and the back-contact cell 110. During the lamination heating process, the adhesive film melts and flows, allowing it to flow into the gap between two adjacent conductive layers 122, thereby filling the gap. After cooling, the melted adhesive film resolidifies. Due to the filling of the adhesive film, the gap between the two adjacent conductive layers 122 is eliminated, thereby improving the structural strength of the cell assembly 100. The adhesive film also protects the conductive layers 122 and the connector layer 123.

[0072] Based on the above-mentioned battery cell assembly 100, please refer to Figure 7 This embodiment also provides a method for preparing a battery cell assembly 100, and the specific steps are as follows:

[0073] S1: providing a plurality of back-contact battery cells 110 and arranging the plurality of back-contact battery cells 110 in sequence.

[0074] S2: Connecting a plurality of positive electrode welding ribbons 130 and a plurality of negative electrode welding ribbons 140 alternately and at intervals to the surface of the back contact battery cell 110 .

[0075] S3: providing at least one connector 120 so that each of two adjacent back-contact battery cells 110 is equipped with one connector 120 .

[0076] S4: Connect two adjacent back-contact battery cells 110 in series using a connector 120 , so that each connection layer 123 is connected to a positive electrode welding ribbon 130 and / or a negative electrode welding ribbon 140 .

[0077] S5: Two laminates and two adhesive films are provided.

[0078] S6: Laying two adhesive films on both sides of the back-contact solar cell 110 respectively.

[0079] S7: Using two laminates to press the back contact cell 110 and the connector 120 , so that during the pressing process, the low melting point material gradually forms a connecting layer 123 .

[0080] It should be noted that if each conductive layer 122 is connected to a connecting layer 123, the connecting layer 123 is connected to the positive electrode welding strip 130 and the negative electrode welding strip 140; if each conductive layer 122 is connected to two connecting layers 123, one connecting layer 123 is connected to the positive electrode welding strip 130, and the other connecting layer 123 is connected to the negative electrode welding strip 140.

[0081] Specifically, the specific steps of S3 also include:

[0082] S31: Lay low melting point material on each welding strip.

[0083] S32: placing a plurality of metal blocks on top of the plurality of welding strips, and making the metal blocks contact with the low melting point material.

[0084] S33: Laying a polyimide film on top of the plurality of metal blocks, so that the polyimide film covers the plurality of metal blocks.

[0085] It should be noted that a structural member made of a low-melting-point material, such as a welding sheet, can be used. The welding sheet is placed on two adjacent back-contact battery cells 110 so that it contacts the corresponding positive electrode welding ribbon 130 and negative electrode welding ribbon 140. A metal block is placed above each welding sheet so that the metal block contacts the welding sheet, that is, the metal block contacts the low-melting-point material. Finally, a polyimide film is laid over the metal block to cover the metal block.

[0086] As can be understood, during the lamination heating process, the low-melting-point material melts to form a connecting layer 123 that connects the metal block and the solder ribbon, allowing the metal block to form a conductive layer 122, connecting two adjacent back-contact battery cells 110 in series and achieving circuit conduction. The polyimide film is connected to the back-contact battery cells 110 by the adhesive film. Due to its flexibility and insulating properties, the polyimide film can form a flexible insulating layer 121.

[0087] It should be noted that in order to prevent the metal block forming the conductive layer 122 from contacting other dotted structures, the flexible insulating layer 121 needs to cover multiple conductive layers 122. Therefore, in this embodiment, the width of the flexible insulating layer 121 should be greater than the width of the conductive layer 122, that is, the width of the polyimide film is greater than the width of the metal block.

[0088] In summary, this embodiment provides a cell assembly 100 that can connect the grid lines on two adjacent back-contact cells 110 via a connection layer 123, thereby enabling electrical conduction between the two back-contact cells 110 via a conductive layer 122. This embodiment utilizes the elastic deformation properties of a flexible insulating layer 121 to provide a deformation space, thereby preventing the soldering ribbon from detaching due to relative displacement of the two back-contact cells 110 during the connection process. Furthermore, this embodiment prevents the soldering ribbon from shifting or twisting due to the flow path of the adhesive film during the lamination process, thereby improving the deformation resistance and aesthetics of the cell assembly 100.

[0089] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A battery cell assembly, characterized in that: include: A plurality of back contact battery sheets (110), wherein the plurality of back contact battery sheets (110) are arranged in sequence; each of the back contact battery sheets (110) is connected to a plurality of welding strips, and the plurality of welding strips are arranged at intervals along the length direction of the back contact battery sheet (110); At least one connecting member (120), the connecting member (120) comprising a flexible insulating layer (121), a plurality of conductive layers (122), and a plurality of connecting layers (123) arranged in sequence; the plurality of conductive layers (122) are arranged at intervals along the length direction of the flexible insulating layer (121) and connected to the same side of the flexible insulating layer (121); each conductive layer (122) is connected to at least one connecting layer (123); Each conductive layer (122) corresponds to two soldering strips located on two adjacent back-contact battery sheets (110); and the connection layer (123) on each conductive layer (122) is connected to the corresponding two soldering strips.

2. The battery cell assembly according to claim 1, wherein: The plurality of welding strips include a plurality of positive electrode welding strips (130) and a plurality of negative electrode welding strips (140), and the plurality of positive electrode welding strips (130) and the plurality of negative electrode welding strips (140) are alternately arranged; The plurality of positive electrode welding strips (130) of one back-contact battery sheet (110) correspond one to one with the plurality of negative electrode welding strips (140) of another back-contact battery sheet (110); One of the positive electrode welding strips (130) and one of the corresponding negative electrode welding strips (140) are connected to the connection layer (123) on the same conductive layer (122).

3. The battery cell assembly according to claim 2, wherein: Each conductive layer (122) is connected to two connecting layers (123), and the two connecting layers (123) are arranged at intervals; the two connecting layers (123) are respectively connected to a corresponding positive electrode welding strip (130) and a corresponding negative electrode welding strip (140).

4. The battery cell assembly according to claim 1, wherein: The connection layer (123) is made of a low-melting-point welding material and is formed by pressing after the welding strip is attached.

5. The battery cell assembly according to claim 4, characterized in that: The thickness of the conductive layer (122) at both ends is greater than the thickness of the conductive layer (122) in the middle.

6. The battery cell assembly according to claim 1, wherein: The cell assembly (100) further comprises two adhesive films and two laminates, the back-contact cell (110) and the connector (120) are both located between the two laminates and in contact with the laminates; Each of the adhesive films is located between one of the laminates and the back-contact battery sheet (110), and is used to fill the space between two adjacent conductive layers (122).

7. The battery cell assembly according to claim 1, wherein: The width of the conductive layer (122) is less than or equal to the width of the flexible insulating layer (121).

8. A method for preparing the battery cell assembly according to any one of claims 1 to 7, characterized in that: The preparation method comprises: Providing a plurality of the back-contact battery sheets (110), and arranging the plurality of back-contact battery sheets (110) in sequence; Connecting a plurality of positive electrode welding strips (130) and a plurality of negative electrode welding strips (140) alternately and at intervals to the surface of the back-contact battery sheet (110); Providing at least one connecting member (120) such that each of two adjacent back-contact battery sheets (110) is equipped with one connecting member (120); The connecting member (120) is used to connect two adjacent back-contact battery sheets (110) in series, so that each connecting layer (123) is connected to one of the positive electrode welding strips (130) and / or one of the negative electrode welding strips (140).

9. The preparation method according to claim 8, characterized in that After the step of connecting two adjacent back-contact battery sheets (110) in series using the connector (120), the preparation method further comprises: Two laminates and two adhesive films are provided; Laying the two adhesive films on both sides of the back-contact battery sheet (110) respectively; The back contact battery sheet (110) and the connecting member (120) are pressed by two of the laminates, so that during the pressing process, the low melting point material gradually forms the connecting layer (123).

10. The preparation method according to claim 8, characterized in that The step of providing at least one of the connecting members (120) comprises: Laying a low melting point material at each of the welding strips; Placing a plurality of metal blocks correspondingly above the plurality of welding strips, and making the metal blocks contact with the low-melting-point material; A polyimide film is laid on the plurality of metal blocks so that the polyimide film covers the plurality of metal blocks.

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