Busbar assembly preparation method, busbar assembly and battery module

Abstract

The invention provides a preparation method of a busbar assembly, the busbar assembly and a battery module, and relates to the technical field of batteries. The preparation method comprises the following steps: sequentially laminating a first insulating layer, a busbar, a flexible circuit board and a second insulating layer; the first insulating layer, the busbar, the flexible circuit board and the second insulating layer which are arranged in a stacked mode are laminated and pre-fixed, and a to-be-fixed assembly is formed; and putting the to-be-fixed assembly into an SMT process line, and carrying out component mounting, hot pressing and welding fixation on the to-be-fixed assembly to obtain the busbar assembly. According to the invention, the first insulating layer, the busbar, the flexible circuit board and the second insulating layer are stacked and placed in the SMT process line together, and the component mounting of the flexible circuit board, the hot pressing of a multi-layer structure and the welding fixation are realized in one SMT process line, so that the production process is saved, the production efficiency is improved, and the equipment cost is reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for preparing a busbar assembly, a busbar assembly and a battery module. Background Art

[0002] The battery module includes a plurality of single cells, which are electrically connected through a bus and collect voltage signals and temperature signals in the battery module by using a flexible circuit board. In the related art, the bus assembly includes a bus, a flexible circuit board, and upper and lower insulating plates, and the bus and the flexible circuit board are arranged between the upper and lower insulating plates. Before the flexible circuit board is arranged between the upper and lower insulating plates, it needs to go through a surface mount technology (Surface Mount Technology, SMT), solder the components to the flexible circuit board, and then solder the bus and the flexible circuit board, and then perform the gluing and pressing processes of the insulating plate, and finally stack the bus, the flexible circuit board, and the upper and lower insulating plates to form a bus assembly.

[0003] The preparation method of the busbar assembly used in the related art requires multiple welding, pressing, gluing and other processes. The large number of processes leads to high preparation costs and reduced production efficiency. Summary of the invention

[0004] The embodiments of the present application provide a method for preparing a bus assembly, a bus assembly and a battery module, so as to improve the problem that the bus assembly has many preparation steps.

[0005] In a first aspect, an embodiment of the present application provides a busbar assembly, comprising:

[0006] The first insulating layer, the bus bar, the flexible circuit board and the second insulating layer are stacked in sequence;

[0007] Pre-fixing the stacked first insulating layer, the busbar, the flexible circuit board and the second insulating layer by lamination to form a component to be fixed;

[0008] The assembly to be fixed is placed in an SMT process line, and components are mounted, hot pressed and welded to the assembly to be fixed, so as to obtain a busbar assembly.

[0009] In some embodiments of the present application, before the step of sequentially stacking the first insulating layer, the busbar, the flexible circuit board, and the second insulating layer, the method further includes:

[0010] Solder paste is coated on a side of the busbar facing the flexible printed circuit board and / or a side of the flexible printed circuit board facing the busbar.

[0011] In some embodiments of the present application, before the step of sequentially stacking the first insulating layer, the busbar, the flexible circuit board, and the second insulating layer, the method further includes:

[0012] Applying glue on a side of the first insulating layer facing the busbar;

[0013] Glue is applied on a side of the second insulating layer facing the flexible circuit board.

[0014] In some embodiments of the present application, the first insulating layer, the second insulating layer, the bus bar, and the flexible circuit board are all integrally formed by stamping.

[0015] In some embodiments of the present application, the step of placing the assembly to be fixed into an SMT process line, mounting components, hot pressing and welding the assembly to be fixed to obtain a busbar assembly includes:

[0016] Put the component to be fixed into the SMT process line, and mount components on the flexible circuit board in the component to be fixed;

[0017] Reflow soldering is performed on the assembly to be fixed on which the components are mounted;

[0018] The components to be fixed that have undergone reflow soldering are subjected to hot pressing and bonding to obtain the busbar component.

[0019] In some embodiments of the present application, the step of reflowing the assembly to be fixed with the components mounted thereon comprises:

[0020] Putting the assembly to be fixed with the components mounted thereon into a reflow oven;

[0021] The temperature in the reflow oven is regulated to melt the solder paste used for welding, thereby completing welding of the components and the flexible circuit board and welding of the flexible circuit board and the bus bar.

[0022] In some embodiments of the present application, the reflow oven is preset with a temperature curve, and the temperature curve includes a preheating section, a reflow section, and a cooling section.

[0023] In some embodiments of the present application, the temperature range of the preheating section is 100°C-180°C, the temperature range of the reflux section is 230°C-250°C, and the temperature range of the cooling section is 0°C-100°C.

[0024] In a second aspect, an embodiment of the present application provides a busbar assembly, wherein the busbar assembly is prepared by the method for preparing the busbar assembly according to the first aspect, and the busbar assembly comprises:

[0025] A first insulating layer and a second insulating layer arranged opposite to each other;

[0026] A bus bar, disposed between the first insulating layer and the second insulating layer;

[0027] A flexible circuit board is provided between the bus bar and the first insulating layer;

[0028] The outer edge of the flexible circuit board is a closed structure, and the flexible circuit board covers the bus. A plurality of hollow portions are provided on the flexible circuit board, and the hollow portions expose the positive and negative portions of the bus.

[0029] In a third aspect, an embodiment of the present application provides a battery module, comprising a plurality of single cells and a bus assembly as described in the second aspect, wherein the plurality of single cells are arranged and distributed along the length direction and the width direction, and along the width direction, adjacent single cells are staggered, and the plurality of single cells are connected to the bus.

[0030] Beneficial effects of the embodiments of the present application:

[0031] The present application provides a method for preparing a busbar assembly, a busbar assembly and a battery module. By stacking a first insulating layer, a busbar, a flexible circuit board and a second insulating layer and placing them together in an SMT process line, the component mounting, hot pressing and welding fixation of the multi-layer structure of the flexible circuit board can be realized in one SMT process line, which saves production processes, improves production efficiency, and can also reduce the investment in production line welding equipment and hot pressing equipment to a certain extent, which is conducive to reducing costs. In detail, firstly, by stacking the first insulating layer, the busbar, the flexible circuit board and the second insulating layer in sequence, the first insulating layer, the busbar, the flexible circuit board and the second insulating layer are pre-formed into a stacked whole, and the stacked whole is the predecessor of the busbar assembly; then the stacked whole is laminated and fixed to form a component to be fixed, so that the component to be fixed can ensure the stability of the stacking in the subsequent process; finally, the component to be fixed is placed in the SMT process line, and the component to be fixed is mounted, hot pressed and welded to obtain the busbar assembly. The entire surface mounting, hot pressing and welding process are completed in one SMT process line. Compared with the related art, it is necessary to first perform a separate SMT process on the flexible circuit board for surface mounting, and then weld the flexible circuit board and the bus, and then stack the insulating board, bus and flexible circuit board and fix them by hot pressing. The preparation process of this application is simpler, and the process line used is only the SMT process line for component mounting on the flexible circuit board. No additional processes or equipment are required, which is conducive to cost saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1It is a schematic flow chart of a method for preparing a busbar assembly provided in an embodiment of the present application;

[0033] Figure 2 is an exploded schematic diagram of a battery module provided in an embodiment of the present application;

[0034] Figure 3 is a structural schematic diagram of a busbar assembly provided in an embodiment of the present application;

[0035] Figure 4 yes Figure 3 Explosion diagram of

[0036] Figure 5 is a structural schematic diagram of a flexible circuit board in a bus assembly provided in an embodiment of the present application;

[0037] Figure 6 is a schematic structural diagram of a bus in a bus assembly provided in an embodiment of the present application;

[0038] Figure 7 It is a schematic diagram of the structure of a busbar in a busbar assembly provided in an embodiment of the present application.

[0039] Description of reference numerals:

[0040] 1. Single cell; 2. Busbar assembly; 21. First insulating layer; 22. Second insulating layer; 23. Busbar; 231. Busbar; 2311. First sub-sheet; 23111. Positive electrode connection portion; 23112. Negative electrode connection portion; 23113. Welding bump; 23114. Positive electrode positioning notch; 23115. Negative electrode positioning notch; 2312. Second sub-sheet; 2313. Inclined section; 232. Positive busbar; 233. Negative busbar; 234. Positive electrode plate; 235. Negative electrode plate; 236. Intermediate busbar; 24. Flexible circuit board; 241. Circuit board body; 2411. Hollow portion group; 24111. First through hole; 24112. Second through hole; 242. Support plate; 243. Welding point; 244. Connector. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise stated, the directional words such as "upper" and "lower" used generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0042] See also Figure 1 , an embodiment of the present application provides a method for preparing a busbar assembly, comprising:

[0043] S1, stacking a first insulating layer, a bus bar, a flexible circuit board and a second insulating layer in sequence;

[0044] S2, laminating and pre-fixing the stacked first insulating layer, busbar, flexible circuit board and second insulating layer to form a component to be fixed;

[0045] S3, placing the component to be fixed into the SMT process line, mounting components, hot pressing and welding the component to be fixed to obtain a busbar component.

[0046] The technical solution provided by the present application realizes the component mounting, hot pressing and welding fixation of the flexible circuit board in one SMT process line by stacking the first insulating layer, busbar, flexible circuit board and second insulating layer and putting them together in the SMT process line, saving production processes, improving production efficiency, and reducing the investment in production line welding equipment and hot pressing equipment to a certain extent, which is conducive to reducing costs. In detail, firstly, the first insulating layer, busbar, flexible circuit board and second insulating layer are stacked in sequence, so that the first insulating layer, busbar, flexible circuit board and second insulating layer are pre-formed into a stacked whole, which is the predecessor of the busbar assembly; then the stacked whole is laminated and fixed to form a component to be fixed, so that the component to be fixed can ensure the stability of the stacking in the subsequent process; finally, the component to be fixed is placed in the SMT process line, and the component to be fixed is mounted with components, hot pressed and welded to obtain a busbar assembly. The entire surface mounting, hot pressing and welding process are completed in one SMT process line. Compared with the related art, it is necessary to first perform a separate SMT process on the flexible circuit board for surface mounting, and then weld the flexible circuit board and the bus, and then stack the insulating board, bus and flexible circuit board and fix them by hot pressing. The preparation process of this application is simpler, and the process line used is only the SMT process line for component mounting on the flexible circuit board. No additional processes or equipment are required, which is conducive to cost saving.

[0047] For step S1: stacking the first insulating layer, bus, flexible circuit board and second insulating layer in sequence, the main purpose is to combine the first insulating layer, bus, flexible circuit board and second insulating layer together to form a whole, which is convenient for subsequent overall welding and hot pressing processes. In addition, it should be noted that when stacking the first insulating layer, bus, flexible circuit board and second insulating layer in sequence, the first insulating layer, bus, flexible circuit board and second insulating layer will be positioned first, and the positioning is generally completed when preparing the first insulating layer, the second insulating layer, bus and flexible circuit board.

[0048] In detail, the first insulating layer, the second insulating layer, the busbar and the flexible circuit board are all stamped and formed in one piece by their own unique molds, which is conducive to improving the strength of each layer and preparing for the subsequent unified welding and hot pressing processes. The first insulating layer and the second insulating layer are stamped and formed by a mold with the same outline size to ensure that the edge contours of the first insulating layer and the second insulating layer can overlap and align. And the first insulating layer and the second insulating layer are stamped and formed into a plate shape, and a plurality of holes are opened on the plate structure so that a part of the busbar located between the first insulating layer and the second insulating layer can be exposed, which is convenient for the subsequent contact between the single cell and the busbar. In addition, a plurality of positioning grooves are also opened on the first insulating layer, and the positive busbar, the negative busbar, the intermediate busbar, the positive plate and the negative plate of the busbar are respectively arranged in the corresponding positioning grooves, and the plurality of busbars of the busbar are aligned with the holes, and one busbar is arranged to be aligned with two holes, and the busbar is stepped, so that the busbar can be positioned and limited by the edge of the hole. Correspondingly, through holes are provided on the flexible circuit board, and holes are provided on the second insulating layer. The stacking is positioned by using the through holes and holes to ensure that the first insulating layer, the second insulating layer, the bus and the flexible circuit board are stacked in the correct position as much as possible.

[0049] In some embodiments, before step S1, that is, before the step of sequentially stacking the first insulating layer, the busbar, the flexible circuit board, and the second insulating layer, the method further includes:

[0050] Solder paste is applied on a side of the busbar facing the flexible circuit board and / or a side of the flexible circuit board facing the busbar.

[0051] Solder paste is applied to the side of the bus facing the flexible circuit board. The solder paste can be applied on the entire surface or at fixed points. In this embodiment, fixed-point application is adopted to prevent the solder paste on the bus from affecting the normal operation of the flexible circuit board and the conductive contact between the bus and the single battery. For specific fixed points, it can be achieved by pre-positioning on the bus or on the flexible circuit board, such as making a mark on the flexible current board. The mark indicates the position of solder paste application. After subsequent welding, the marked position is the soldering point. Of course, in other embodiments, the solder paste can also be applied to the side of the flexible circuit board facing the bus. The specific coating position is the pre-positioned position, or the solder paste is applied on both the bus and the flexible circuit board, without limitation.

[0052] It should be noted that the coating of solder paste is mainly carried out by screen printing, and the specific printing process belongs to conventional means in the field and will not be described in detail here.

[0053] In this embodiment, the coating material is solder paste, mainly because it has a low melting point and is suitable for the reflow process. In the reflow process, the solder paste is uniformly soldered through the reflow furnace to form a high-strength connection, and the good conductivity and oxidation resistance of the solder paste ensure the conductivity of the connection, and can also prevent oxidation and increase the life of the solder joint.

[0054] Correspondingly, the material of the busbar is metallic nickel, because nickel has good electrical conductivity and is very suitable for soldering with solder paste.

[0055] In some embodiments, before step S1, that is, before the step of sequentially stacking the first insulating layer, the busbar, the flexible circuit board, and the second insulating layer, the method further includes:

[0056] Apply glue to the side of the first insulation layer facing the busbar;

[0057] Apply glue on the side of the second insulating layer facing the flexible circuit board.

[0058] By applying glue on the first insulating layer and the second insulating layer, it is mainly to prepare for the subsequent hot pressing fixation. Applying the glue in advance is not only conducive to the overall hot pressing of the subsequent SMT process, but also plays a role in the preliminary fixation of the lamination setting of the first insulating layer, bus, flexible circuit board and the second insulating layer before entering the SMT process line.

[0059] It should be noted that there is no particular order for the step of coating glue on the side of the first insulating layer facing the bus and the step of coating glue on the side of the second insulating layer facing the flexible circuit board and the step of coating solder paste on the side of the bus facing the flexible circuit board and / or the side of the flexible circuit board facing the bus. Any one of the steps can be performed first, or they can be performed simultaneously because the steps are independent of each other.

[0060] In some embodiments, step S3, i.e., placing the assembly to be fixed in the SMT process line, mounting components, hot pressing, and welding the assembly to be fixed to obtain the busbar assembly, specifically includes:

[0061] S31. Place the component to be fixed into the SMT process line, and mount components on the flexible circuit board in the component to be fixed.

[0062] Specifically, the components are mounted one by one on the flexible circuit board according to the preset programming program through the placement machine. When the placement machine is running at high speed, it can automatically calibrate according to the size and placement position of the components to ensure that the components are accurately placed on the flexible circuit board. At the same time, the bus enters the placement process together with the flexible circuit board at this time. The placement machine places the bus at the predetermined welding position of the flexible circuit board according to the programming instructions, and physically fixes the bus and the flexible circuit board together, laying the foundation for subsequent welding and hot pressing bonding.

[0063] Among them, the flexible circuit board includes a circuit board body and a connector. The circuit board body is provided with a temperature sensor and a voltage sensor, and the circuit board body is electrically connected to the connector to realize real-time collection and transmission of key parameter information of the battery module, such as voltage and temperature. The circuit board body covers between the positive and negative parts of the bus, and exposes the positive and negative electrodes in the bus through multiple hollow parts opened on it, which is convenient for the subsequent electrical connection of the bus. The circuit board body is made of a material with flexibility and good conductivity, such as polyimide or other suitable flexible substrates, so as to ensure that it can be flexibly arranged in the complex space of the battery module.

[0064] In order to monitor the working status of the battery module, a temperature sensor (not shown in the figure) and a voltage sensor (not shown in the figure) are integrated on the circuit board body. These sensors are located at different positions of the circuit board body and are used to collect temperature signals and voltage signals of the battery module. In practical applications, the temperature sensor can be arranged in the part of the battery module close to the current channel to accurately monitor the heat generated by the bus and the single cell during operation. The voltage sensor is arranged at the key nodes of the battery module to detect the voltage changes of each single cell in real time.

[0065] The connector is located at one end of the circuit board body and is electrically connected to the temperature sensor and voltage sensor on the circuit board body. Through the connector, the collected voltage and temperature signals can be transmitted to an external control system or a battery management system (BMS). The connector can adopt a standard multi-pin design to ensure a stable electrical connection and support high-speed data transmission. The choice of connector 244 material is also very important. Its shell should have high durability and anti-interference performance to ensure that the transmission of sensor data is not affected by electromagnetic interference or the environment.

[0066] S32, reflow soldering is performed on the assembly to be fixed with components mounted thereon.

[0067] The entire assembly to be fixed is placed in the reflow oven, so that the solder paste gradually melts at an appropriate temperature and completes the welding of components and flexible circuit boards. At the same time, under the high temperature of the reflow oven, the solder paste melts and forms welding points with the busbar and the flexible circuit board to achieve electrical connection. The nickel material of the busbar is combined with the solder paste, the welding strength is good, and the overcurrent capacity can also be guaranteed.

[0068] In some embodiments, the step of reflowing the assembly to be fixed with components mounted thereon specifically includes:

[0069] Place the assembly to be fixed with components mounted thereon into a reflow oven;

[0070] The temperature in the reflow oven is regulated to melt the solder paste used for soldering, thereby completing the soldering of components and the flexible circuit board and the soldering of the flexible circuit board and the bus bar.

[0071] Furthermore, the reflow oven is provided with a temperature curve, which includes a preheating section, a reflow section and a cooling section. The temperature range of the preheating section is 100°C-180°C, the temperature range of the reflow section is 230°C-250°C, and the temperature range of the cooling section is 0°C-100°C.

[0072] In detail, after the assembly to be fixed enters the reflow oven, the flexible circuit board and components are slowly heated to a certain temperature. In this embodiment, the temperature range is 150°C to 180°C, so that the temperature of the assembly to be fixed is uniform. The heating rate of the preheating section is controlled at 1-3°C / second to prevent the flexible circuit board and components from being heated unevenly and causing thermal stress, and to avoid component damage and solder paste splashing. The heating time range of the preheating section can be set to 60-120 seconds to ensure that the bus, flexible circuit board and components reach a suitable temperature, providing sufficient time for the activation of the flux added to the solder paste.

[0073] After the preheating section is over, it enters the reflow section. Specifically, compared with the preheating section, the temperature in the reflow section rises rapidly to the melting point of tin, which ranges from 230-250°C. The specific temperature depends on the melting point of lead-free or lead-containing solder paste). The solder paste is completely melted, contacts the soldering surfaces of the components and forms a firm connection. The time of the reflow section is controlled between 30-60 seconds to avoid damage to components or brittle solder joints due to excessive heating. It should be noted that the reflow temperature of lead-free solder paste is controlled between 240°C and 245°C, while the reflow temperature of lead-containing solder paste is controlled between 220°C and 230°C.

[0074] After the reflow section is over, it enters the cooling section. After the flexible circuit board passes through the peak temperature zone, it quickly enters the cooling section for cooling, and the temperature gradually drops to room temperature at a cooling rate of 4°C / second. Through slow cooling, the solder joints can gradually solidify and form a stable metal bond, avoiding stress and solder joint cracks caused by too fast cooling. Ensure that the temperature changes in the cooling section are stable and will not cause thermal stress in the solder joints, otherwise it may cause welding defects such as cracks and cold solder joints.

[0075] The temperature curve of reflow soldering is divided into three stages: preheating, reflow, and cooling. In the preheating stage, the heating rate is controlled to ensure that the circuit board and components are gradually heated up to avoid temperature stress caused by too fast heating. In the reflow stage, the appropriate peak temperature and holding time are set to ensure that the solder paste is completely melted and fully contacted with the preset solder joint position to ensure the welding strength. In the cooling stage, the cooling rate is properly controlled to avoid stress cracks in the solder joints due to too fast cooling.

[0076] Furthermore, in some embodiments, in addition to the above three time periods, the temperature curve also adds a heat preservation section, which is located between the preheating section and the reflow section. In this temperature section, the preset solder joint position and the temperature of the solder paste are maintained in a relatively high range. In this embodiment, the temperature is maintained in the range of 180°C to 200°C. The flux is fully activated at this stage to remove the oxides on the surface of the solder joints and enhance the welding effect. Through the heat preservation section, the temperature of the flexible circuit board and components gradually reaches uniformity, and the activation of the flux can effectively remove the oxides, thereby ensuring the subsequent welding quality. The time range of the heat preservation section is 90-120 seconds to ensure that the active ingredients of the solder paste fully function and form a good wetting effect.

[0077] S33, subjecting the components to be fixed that have undergone reflow soldering to hot pressing bonding to obtain a busbar component.

[0078] Specifically, before hot pressing, the first insulating layer, busbar, flexible circuit board, and second insulating layer are stacked and accurately aligned in sequence. This part of the process is completed in step S1 and step S2 to ensure the accurate position of the welding points, contact points, and insulating layers. After stacking and alignment, the components to be fixed are cleaned and inspected to ensure that there is no dust or impurities on the surface of each layer of material, especially the welding point area between the busbar and the flexible circuit board, so as to avoid affecting the bonding effect or causing electrical failure.

[0079] The hot pressing temperature range of the hot pressing equipment is preset to 150℃ to 180℃ to ensure that the glue is completely melted at this temperature and will not be over-carbonized. The hot pressing pressure range of the hot pressing equipment is preset to 0.3MPa to 1.5MPa to ensure that each layer is evenly attached, but will not damage the structure of the flexible circuit board and other components. The hot pressing time of the hot pressing equipment is preset to 10 to 30 seconds to ensure that the glue is fully melted and combined with the surface of the material, while avoiding potential damage to the components due to excessive heat.

[0080] When the equipment reaches the preset temperature, the component to be fixed is placed between the upper and lower heating plates of the hot press. At this time, the hot press starts to heat, and the pre-applied glue on the first and second insulating layers gradually softens and melts. As the glue begins to melt, the hot press gradually applies pressure. The uniform application of pressure can ensure that the bus, flexible circuit board and insulating layer fit tightly and prevent the formation of bubbles or gaps. Maintain the set temperature and pressure for a period of time to allow the glue to fully infiltrate the surface of the material and form a strong bond. After the hot pressing process is completed, slowly reduce the temperature to allow the glue to gradually cool and solidify under pressure, which helps to avoid internal stress or material deformation caused by sudden cooling. After the temperature drops to a certain level, release the pressure and take out the assembled components. At this time, the bus, flexible circuit board, first insulating layer and second insulating layer in the component are firmly combined together to form an overall structure with good electrical insulation and mechanical stability.

[0081] In some embodiments, in step S3, i.e., after the step of placing the assembly to be fixed in the SMT process line, mounting components, hot pressing and welding the assembly to be fixed to obtain the busbar assembly, the process further includes:

[0082] Clean the busbar components;

[0083] Perform quality inspection on the busbar assembly after cleaning.

[0084] Specifically, after completing the hot pressing bonding, the appearance of the bus assembly is inspected to ensure that there are no bubbles, delamination or offset; then a peel test is performed to verify the bonding strength and to check whether the bonding force between the bus, the flexible circuit board and the insulation layer meets the requirements; then a conductivity test is performed to ensure that the electrical connection between the solder joints between the bus and the flexible circuit board is normal, and insulation testing is performed to confirm the isolation performance of the insulating film.

[0085] See also Figures 2 to 7, the embodiment of the present application further provides a battery module, comprising a plurality of single cells 1 and a bus assembly 2. The plurality of single cells 1 are arranged and distributed along the length direction and the width direction of the bus assembly 2. Specifically, the plurality of single cells 1 are arranged in sequence along the length direction of the bus assembly 2 to form a column of single cells 1, and the plurality of columns of single cells 1 are arranged in sequence along the width direction of the bus assembly 2. Also, because the single cells 1 are cylindrical batteries, the adjacent single cells 1 are staggered along the width direction, so that the adjacent single cells 1 in the width direction can make up for the gap caused by the cylindrical shape of the battery, thereby making the arrangement of the plurality of single cells 1 more compact, saving the internal space of the battery module, and improving the battery integration.

[0086] Multiple single cells 1 are connected to the bus assembly 2, which is used to electrically connect the multiple single cells 1 and monitor the working conditions of the single cells 1 in real time. Compared with each single cell 1 being electrically connected using a connector separately, the circuit is simpler.

[0087] It should be noted that the busbar assembly 2 is prepared by the preparation method of the busbar assembly described in any of the aforementioned embodiments.

[0088] In some embodiments, see Figures 3 to 7 , the busbar assembly 2 comprises:

[0089] A first insulating layer 21 and a second insulating layer 22 arranged opposite to each other;

[0090] The busbar 23 is provided between the first insulating layer 21 and the second insulating layer 22;

[0091] The flexible circuit board 24 is provided between the bus bar 23 and the first insulating layer 21;

[0092] The outer edge of the flexible circuit board 24 is a closed structure, and the flexible circuit board 24 covers the bus 23 . A plurality of hollow portions are provided on the flexible circuit board 24 to expose the positive and negative portions of the bus 23 .

[0093] In detail, the busbar assembly 2 includes a first insulating layer 21 and a second insulating layer 22 arranged opposite to each other, and a busbar 23 located therebetween. The busbar 23 is a core component used to connect multiple single cells 1 in a battery module, through which the collection and distribution of electrical energy can be achieved. The first insulating layer 21 and the second insulating layer 22 are made of materials with high insulation performance to ensure electrical isolation and prevent the battery module from electrical short circuit during operation. The two layers of insulating materials are arranged opposite to each other, covering the upper and lower surfaces of the busbar 23 to form an overall busbar 23 structure. The busbar 23 is located between the above two layers of insulating materials and is responsible for connecting the positive and negative electrodes of each single cell 1 to form the electrical connection of the battery module. The material of the busbar 23 can be copper, aluminum or other metal materials with excellent electrical conductivity, and its surface can be tinned or otherwise treated with anti-corrosion as needed to improve its durability and electrical conductivity. In this embodiment, the material of the bus 23 is nickel, which facilitates the welding between the bus 23 and the flexible circuit board 24. Specifically, nickel can be directly soldered to the flexible circuit board 24 through tin, and the welding bonding force is greater under the condition of satisfying the overcurrent. A flexible circuit board 24 is arranged between the first insulating layer 21 of the bus 23 and the bus 23. The flexible circuit board 24 is a plate structure, covering a surface of the bus 23. Unlike the multiple flexible sub-boards in the prior art, the flexible circuit board 24 in the present invention covers the bus 23 at one time, which greatly reduces the complexity of installation and the number of alignment operations. In order to realize the electrical connection between the positive and negative poles of the battery, a plurality of hollow parts are provided on the flexible circuit board 24. These hollow parts are used to expose the positive and negative parts of the bus 23, so as to realize the electrical connection between the battery and the bus 23, so as to make the electrical connection of the battery module easier, and at the same time avoid the installation error caused by multiple alignment operations.

[0094] In this embodiment, the number and shape of the hollow portions are matched according to the structure of the busbar 23 to ensure accurate exposure and good contact of the positive and negative electrodes. Specifically, the hollow portions can be rectangular, circular or other suitable shapes, and are evenly arranged along the length direction of the flexible circuit board 24, so as to achieve multi-point simultaneous connection.

[0095] The technical solution provided in the present application sets the flexible circuit board 24 as a plate body, and opens a plurality of hollow parts on the flexible circuit board 24 for exposing the positive and negative parts of the bus 23, so that the flexible circuit board 24 can be integrally formed into a plate shape without interfering with the exposure of the positive and negative electrodes of the bus 23. Therefore, when the bus 23, the flexible circuit board 24, the first insulating layer 21 and the second insulating layer 22 are stacked and assembled, only one alignment and one unified welding are required to realize the assembly and fixation of the multi-layer accessories, which is beneficial to improve the efficiency of the assembly and molding of the bus assembly 2, and then improve the production efficiency of the battery module.

[0096] In some embodiments, see Figure 5 The flexible circuit board 24 includes a circuit board body 241 and a connector 244. The circuit board body 241 is provided with a temperature sensor and a voltage sensor, and the circuit board body 241 is electrically connected to the connector 244 to realize real-time collection and transmission of key parameter information of the battery module, such as voltage and temperature. The circuit board body 241 covers between the positive and negative parts of the bus 23, and exposes the positive and negative electrodes in the bus 23 through a plurality of hollow parts opened thereon, so as to facilitate the subsequent electrical connection of the bus 23. The circuit board body 241 is made of a material with flexibility and good conductivity, such as polyimide or other suitable flexible substrates, so as to ensure that it can be flexibly arranged in the complex space of the battery module.

[0097] In order to monitor the working state of the battery module, a temperature sensor (not shown in the figure) and a voltage sensor (not shown in the figure) are integrated on the circuit board body 241. These sensors are respectively located at different positions of the circuit board body 241 and are used to collect temperature signals and voltage signals of the battery module. In practical applications, the temperature sensor can be arranged at the part of the battery module close to the current channel to accurately monitor the heat generated by the bus 23 and the single cell 1 during operation. The voltage sensor is arranged at the key nodes of the battery module to detect the voltage changes of each single cell 1 in real time.

[0098] The connector 244 is provided at one end of the circuit board body 241 and is electrically connected to the temperature sensor and the voltage sensor on the circuit board body 241. Through the connector 244, the collected voltage and temperature signals can be transmitted to an external control system or a battery management system (BMS). The connector 244 can adopt a standard multi-pin design to ensure a stable electrical connection and support high-speed data transmission. The choice of the material of the connector 244 is also very important. Its shell should have high durability and anti-interference performance to ensure that the transmission of sensor data is not affected by electromagnetic interference or the environment.

[0099] During the installation process, the integrated design of the circuit board body 241 not only simplifies the installation steps of the flexible circuit board 24, but also avoids the problem of unstable electrical connection caused by inaccurate alignment of multiple sub-boards. At the same time, the integrated temperature and voltage sensor design enables the battery module to monitor the core parameters in real time during operation, effectively improving the safety and reliability of the battery system.

[0100] Furthermore, the flexible circuit board 24 also includes a support plate 242, which is arranged at one end of the circuit board body 241, and the connector 244 is located on the support plate 242. The support plate 242 is made of a hard material, such as a glass fiber reinforced material or a metal sheet, which is different from the substrate of the circuit board body 241, and it can effectively prevent bending and deformation of this area. The support plate 242 is arranged at the connection end of the circuit board body 241, that is, the position where the flexible circuit board 24 is electrically connected to the external device. Through this design, the support plate 242 can effectively improve the mechanical stability of the connection end of the flexible circuit board 24, and avoid damage to the flexible circuit board 24 due to frequent plugging and unplugging or other external forces. By arranging the connector 244 on the support plate 242, not only can the stable installation of the connector 244 be ensured, but also other parts of the flexible circuit board 24 can be prevented from being damaged due to frequent connection operations. In addition, the presence of the support plate 242 enables the connector 244 to be firmly fixed on the flexible circuit board 24, ensuring that it maintains a stable electrical connection during long-term use.

[0101] In some embodiments, a plurality of hollow portions are arranged along the length direction of the flexible circuit board 24 to form a hollow portion group 2411, and the plurality of hollow portion groups 2411 are arranged at intervals along the width direction of the flexible circuit board 24. The busbar 23 includes a plurality of busbar groups, and the plurality of busbar groups are arranged at intervals along the width direction, and at least a portion of a busbar group is aligned with a hollow portion group 2411. By aligning at least a portion of a busbar group with a hollow portion group 2411, it is possible to ensure that the positive and negative portions of each single battery 1 in the battery module can be accurately connected to the corresponding portion of the busbar 23. Specifically, the hollow portion groups 2411 are arranged at intervals consistent with the busbar groups, and are all aligned and installed in groups, which is conducive to reducing the adjustment time during the installation process and improving the stability of the electrical connection.

[0102] In some embodiments, the hollow portion group 2411 includes a plurality of first through holes 24111 and a plurality of second through holes 24112. The plurality of first through holes 24111 are arranged in a connected manner along the length direction, and the plurality of second through holes 24112 are arranged at intervals along the length direction. The first through holes 24111 are a group of connected holes arranged along the length direction of the flexible circuit board 24. The first through holes 24111 are arranged in a continuous connected manner, that is, each first through hole 24111 is connected to each other to form a channel along the length direction. Through this continuous arrangement, the first through holes 24111 can expose a portion of the busbar group in a longer area, ensuring that the contact area of ​​the electrical connection is large enough. Relative to the first through holes 24111, the second through holes 24112 are arranged at intervals along the length direction of the flexible circuit board 24. The position of the second through holes 24112 is adjacent to the first through holes 24111, but they are not arranged in a connected manner, but are distributed on the flexible circuit board 24 in an interval form. The second through hole 24112 is usually circular, rectangular or other irregular shapes, without limitation, as long as the corresponding portion of the busbar assembly can be exposed.

[0103] In addition, the spaced arrangement design of the first through hole 24111 and the second through hole 24112 also has a heat dissipation function. Through the presence of these through holes, part of the bus bar 23 can be directly exposed, which helps to dissipate the heat generated by the battery module during operation in a timely manner, reduces the operating temperature of the bus bar 23, and facilitates the flexible circuit board 24 to detect the temperature inside the battery module.

[0104] Furthermore, the plurality of first through holes 24111 and the plurality of second through holes 24112 are staggered in the width direction to accommodate the staggered arrangement of the plurality of single cells 1 in the width direction, ensuring that each single cell 1 can be connected to the corresponding busbar group through the first through hole 24111 and the second through hole 24112 .

[0105] Furthermore, a plurality of solder joints 243 are formed on the flexible circuit board 24, and along the length direction, each solder joint 243 is located between two adjacent first through holes 24111. The solder joints 243 are arranged between two adjacent first through holes 24111, so as to make full use of the space of the flexible circuit board 24 in the length direction, and the solder joints 243 are formed between two adjacent first through holes 24111, which is also conducive to improving the uniformity and stability of the soldering fixation.

[0106] In some embodiments, see Figure 6, the busbar group includes a plurality of busbars 231. The plurality of busbars 231 are arranged at intervals along the length direction, and each busbar 231 is arranged in alignment with at least two adjacent first through holes 24111 and two adjacent second through holes 24112, and the two first through holes 24111 and the two second through holes 24112 are staggered in the width direction. It should be noted that the four staggered first through holes 24111 and the second through holes 24112 specifically refer to two first through holes 24111 and two second through holes 24112 adjacent in the length direction, and the two first through holes 24111 and the corresponding two second through holes 24112 are staggered in the width direction. Through this staggered arrangement, reliable electrical contact between the busbar 231 and the positive and negative electrode parts can be ensured, and the connection stability of the entire busbar assembly 2 can be improved. In more detail, when each busbar 231 is arranged in the length direction, its connection portion spans two first through holes 24111 and two second through holes 24112 in the length direction, and in the width direction, spans adjacent first through holes 24111 and second through holes 24112. By staggering the busbars 231 and through holes in the width direction, the space of the flexible circuit board 24 can be more efficiently utilized, mutual interference between through holes can be avoided, and the independence of electrical connection can be ensured.

[0107] In some embodiments, the busbar 231 includes a first sub-piece 2311, a second sub-piece 2312, and an inclined section 2313. The first sub-piece 2311 and the second sub-piece 2312 are connected by the inclined section 2313, and the first sub-piece 2311 and the second sub-piece 2312 are staggered in the width direction. A portion of the first sub-piece 2311 is aligned with a first through hole 24111, and a portion is aligned with an adjacent first through hole 24111, even if the first sub-piece 2311 can expose two portions through two adjacent first through holes 24111 in the length direction, the electrical properties of the two portions are opposite. Similarly, a portion of the second sub-piece 2312 is aligned with a second through hole 24112, and a portion is aligned with an adjacent second through hole 24112, even if the second sub-piece 2312 can expose two portions through two adjacent second through holes 24112 in the length direction, the electrical properties of the two portions are opposite. The first sub-chip 2311 and the second sub-chip 2312 have the same structure and size, which facilitates the centralized production of the busbar 231. The first sub-chip 2311 and the second sub-chip 2312 are connected by the inclined section 2313, which can ensure that the first sub-chip 2311 and the second sub-chip 2312 are staggered in the width direction and reduce the number of alignments of the busbar 231.

[0108] Further, the first sub-sheet 2311 includes a positive electrode connection portion 23111, a negative electrode connection portion 23112, and a welding bump 23113. The positive electrode connection portion 23111 and the negative electrode connection portion 23112 are integrally formed along the length direction, and the welding bump 23113 is provided on the positive electrode connection portion 23111 and protrudes toward the direction of the second insulating layer 22. The welding bump 23113 protrudes toward the direction of the second insulating layer 22 to facilitate welding of the first sub-sheet 2311. The positive electrode connection portion 23111 of the first sub-sheet 2311 is aligned and connected to a first through hole 24111, so that the first through hole 24111 can expose the positive electrode connection portion 23111, and the negative electrode connection portion 23112 is aligned and connected to another first through hole 24111 adjacent to the length direction, so that the other first through hole 24111 can expose the negative electrode connection portion 23112. Similarly, since the second sub-chip 2312 and the first sub-chip 2311 have the same structural dimensions, the second sub-chip 2312 also has corresponding positive electrode connecting portion 23111, negative electrode connecting portion 23112 and welding bump 23113, which will not be described in detail here.

[0109] Furthermore, the positive electrode connection part 23111 is provided with a positive electrode positioning notch 23114, and the negative electrode connection part 23112 is provided with a negative electrode positioning notch 23115. The positive electrode positioning notch 23114 and the negative electrode positioning notch 23115 are aligned in the length direction. When the busbar 23 is stacked on the single battery 1, the positive electrode positioning notch 23114 and the negative electrode positioning notch 23115 of the positive electrode connection part 23111 and the negative electrode connection part 23112 respectively cooperate with the preset positioning plate, so that the busbar 23 can be accurately and quickly stacked on the single battery 1, and then the positioning plate can be removed.

[0110] In some embodiments, the busbar 23 further includes a positive busbar 232, a negative busbar 233, a positive plate 234, a negative plate 235, and a plurality of intermediate busbars 236. The positive plate 234 and the negative plate 235 are disposed diagonally opposite to each other. Specifically, the busbar 23 is rectangular, and the positive plate 234 and the negative plate 235 are located near diagonally opposite corners. The positive plate 234 is connected to the positive busbar 232, the negative plate 235 is connected to the negative busbar 233, the end of the positive busbar 232 away from the positive plate 234 is respectively connected to the positive connection part 23111 of the first sub-sheet 2311 and the positive connection part 23111 of the second sub-sheet 2312 of a busbar 231, and the end of the negative busbar 233 away from the negative plate 235 is respectively connected to the negative connection part 23112 of the first sub-sheet 2311 and the negative connection part 23112 of the second sub-sheet 2312 of a busbar 231, and the integrated connection of multiple single cells 1 can be realized through one positive busbar 232, one negative busbar 233, multiple busbar groups, and multiple intermediate busbars 236. The number of single cells 1 is much larger than the number of intermediate busbars 236, and also larger than the number of busbars 231. The first sub-sheet 2311 in each busbar 231 is connected to one single battery 1 , and the second sub-sheet 2312 is connected to one single battery 1 , that is, one busbar 231 can be connected to two single batteries 1 at the same time.

[0111] In addition, the intermediate busbars 236 are arranged in the width direction and the length direction, and the multiple intermediate busbars 236 are all located on the current path conducted by the positive busbar 232 and the negative busbar 233, and the current path is serpentine. Specifically, at least one intermediate busbar 236 is arranged in the width direction. In this embodiment, two intermediate busbars 236 are arranged in the width direction, and at least two intermediate busbars 236 are arranged in the length direction. The two intermediate busbars 236 are staggered in the length direction to correspond to the oblique arrangement of the positive plate 234 and the negative plate 235. At this time, the current path is to flow from the positive electrode plate 234 through the first intermediate bus plate 236 along the length direction, and then flow through the intermediate bus plate 236 along the length direction toward another intermediate bus plate 236 opposite to it, and then flow toward another intermediate bus plate 236, so that the current flow path is in the shape of a snake winding back and forth. Correspondingly, the structure composed of the positive bus plate 232, multiple intermediate bus plates 236 and the negative bus plate 233 is in the shape of a snake, thereby improving the integration of multiple single battery cells 1.

[0112] It should also be noted that the intermediate busbar 236 has four connection ends, that is, one intermediate busbar 236 can connect two groups of busbar groups that are adjacent in the width direction, which is beneficial to cost saving.

[0113] In summary, the technical solution provided by the present application is mainly to set the flexible circuit board 24 as a plate body, and to open a plurality of hollow parts on the flexible circuit board 24 for exposing the positive and negative parts of the bus 23, so that the flexible circuit board 24 can be integrally formed into a plate shape without interfering with the exposure of the positive and negative poles of the bus 23. Therefore, when the bus 23, the flexible circuit board 24, the first insulating layer 21 and the second insulating layer 22 are stacked and assembled, only one alignment and one unified welding are required to realize the assembly and fixation of the multi-layer accessories, which is beneficial to improve the efficiency of the assembly and molding of the bus assembly 2, and then improve the production efficiency of the battery module.

[0114] The embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a busbar assembly, characterized in that: include: The first insulating layer, the bus bar, the flexible circuit board and the second insulating layer are stacked in sequence; Pre-fixing the stacked first insulating layer, the busbar, the flexible circuit board and the second insulating layer by lamination to form a component to be fixed; The assembly to be fixed is placed in an SMT process line, and components are mounted, hot pressed and welded to the assembly to be fixed, so as to obtain a busbar assembly.

2. The method for preparing a busbar assembly according to claim 1, wherein: Before the step of sequentially stacking the first insulating layer, the busbar, the flexible circuit board and the second insulating layer, the method further includes: Solder paste is coated on a side of the busbar facing the flexible printed circuit board and / or a side of the flexible printed circuit board facing the busbar.

3. The method for preparing a busbar assembly according to claim 2, wherein: Before the step of sequentially stacking the first insulating layer, the busbar, the flexible circuit board and the second insulating layer, the method further includes: Applying glue on a side of the first insulating layer facing the busbar; Glue is applied on a side of the second insulating layer facing the flexible circuit board.

4. The method for preparing a busbar assembly according to claim 3, characterized in that: The first insulating layer, the second insulating layer, the bus bar and the flexible circuit board are all integrally formed by stamping.

5. The method for preparing a busbar assembly according to any one of claims 1 to 4, characterized in that: The step of placing the assembly to be fixed into an SMT process line, mounting components, hot pressing and welding the assembly to be fixed to obtain a busbar assembly comprises: Put the component to be fixed into the SMT process line, and mount components on the flexible circuit board in the component to be fixed; Reflow soldering is performed on the assembly to be fixed on which the components are mounted; The components to be fixed that have undergone reflow soldering are subjected to hot pressing and bonding to obtain the busbar component.

6. The method for preparing a busbar assembly according to claim 5, characterized in that: The step of reflowing the assembly to be fixed with the components mounted thereon comprises: Putting the assembly to be fixed with the components mounted thereon into a reflow oven; The temperature in the reflow oven is regulated to melt the solder paste used for welding, thereby completing welding of the components and the flexible circuit board and welding of the flexible circuit board and the bus bar.

7. The method for preparing a busbar assembly according to claim 6, characterized in that: The reflow oven is preset with a temperature curve, which includes a preheating section, a reflow section and a cooling section.

8. The method for preparing a busbar assembly according to claim 7, characterized in that: The temperature range of the preheating section is 100°C-180°C, the temperature range of the reflux section is 230°C-250°C, and the temperature range of the cooling section is 0°C-100°C.

9. A busbar assembly, characterized in that: The busbar assembly is prepared by the method for preparing a busbar assembly according to any one of claims 1 to 8, and the busbar assembly comprises: A first insulating layer and a second insulating layer arranged opposite to each other; A bus bar, disposed between the first insulating layer and the second insulating layer; A flexible circuit board is provided between the bus bar and the first insulating layer; The outer edge of the flexible circuit board is a closed structure, and the flexible circuit board covers the bus. A plurality of hollow portions are provided on the flexible circuit board, and the hollow portions expose the positive and negative portions of the bus.

10. A battery module, characterized in that: It comprises a plurality of single cells and a busbar assembly as claimed in claim 9, wherein the plurality of single cells are arranged and distributed along the length direction and the width direction, and along the width direction, adjacent single cells are staggered, and the plurality of single cells are connected to the busbar.

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