Battery module

Abstract

A battery module (1) comprises: a battery body (10) in which a battery cell (11) with a tab (12) extending in the X direction is plurally stacked in the Z direction; and a circuit board (20) disposed to face the battery body (10) in the X direction. The circuit board (20) has an opening (22) that penetrates in the X direction. The opening (22) comprises a first opening lateral surface (231) and a second opening lateral surface (211) that face each other in the Z direction. The circuit board (20) comprises: a busbar (23) that constitutes the first opening lateral surface (231) of the opening (22); and a securing member (24) that is disposed along the second opening lateral surface (211) of the opening (22) to hold the tab (12) in place. The tab (12) is inserted into the opening (22), held between the busbar (23) and the securing member (24), and joined to the busbar (23).

Description

Battery module

[0001] The present invention relates to a battery module.

[0002] A technology for joining tabs of multiple battery cells provided in a battery main body to a bus bar is known (see, for example, Patent Document 1). In Patent Document 1, the bus bar is provided with a terminal insertion hole and a joining protrusion that rises from the terminal insertion hole. In this configuration, the tab is inserted into the terminal insertion hole along the joining protrusion, and the joining protrusion and the tab are clamped by a pressure jig to bring them into surface contact, and the joining protrusion and the tip of the tab are welded.

[0003] Japanese Patent Application Laid-Open No. 2019-153555

[0004] However, with the configuration of Patent Document 1, if it is desired to join all the tabs and joining protrusions in a single welding process, a pressure tool that brings the tabs and joining protrusions into surface contact is required for each combination of tabs and joining protrusions to be joined, which increases the labor costs associated with welding.

[0005] Furthermore, a battery module may include, in addition to the battery itself, a battery monitoring system that manages the thermal state and charging state of the battery itself. The technology described in Patent Document 1 is configured so that the tabs of each battery cell of the battery itself are connected only to a bus bar. When incorporating a battery monitoring system as described above, it is necessary to wire the bus bar to the circuit board on which the battery monitoring system is mounted. However, this type of wire connection requires space for wiring, and is therefore unable to adequately accommodate the miniaturization of battery modules.

[0006] An object of the present invention is to provide a battery module that can be miniaturized and that can join the tabs of the battery cells to a circuit board on which a battery monitoring system is arranged at low cost.

[0007] A battery module according to one aspect of the present invention includes a battery body configured by stacking a plurality of battery cells in a second direction, each battery cell having a tab extending in a first direction, and a circuit board arranged opposite the battery body in the first direction. The circuit board has an opening extending through the first direction, and the circuit board includes a conductive member forming a first opening side surface of the opening along the second direction, and a fixing member arranged along a second opening side surface opposite the first opening side surface of the opening. The tab is inserted into the opening of the circuit board, sandwiched between the fixing member and the conductive member, and joined to the conductive member.

[0008] This electrically connects the conductive member provided on the circuit board to the tab, eliminating the need for separate wiring to connect the battery main body and the circuit board, and promoting the miniaturization of the battery module. In addition, because the tab is clamped and fixed between the fixing member and the conductive member, multiple pressure jigs are not required to bring the tab into surface contact with the conductive member when joining the tab to the conductive member, and the cost of the welding process to join the tab and the conductive member can be reduced.

[0009] FIG. 1 is an overall view showing a schematic configuration of a battery module of a first embodiment. FIG. 2 is an exploded perspective view showing a portion of the battery module of FIG. 1 disassembled. FIG. 3 is a plan view showing a schematic configuration of a circuit board of the present embodiment. FIG. 4 is a cross-sectional view of the circuit board cut along line A-A in FIG. 3. FIG. 5 is an enlarged cross-sectional view of the vicinity of a bus bar of the circuit board in FIG. 4. FIG. 6 is a perspective view of a fixing member of the present embodiment. FIG. 7 is a diagram showing an example of a method for joining a tab to a circuit board. FIG. 8 is an enlarged cross-sectional view of the vicinity of a bus bar of a circuit board of a second embodiment.

[0010] First Embodiment A battery module according to a first embodiment of the present invention will be described. FIG. 1 is an overall view showing a schematic configuration of a battery module 1 according to this embodiment. FIG. 2 is an exploded perspective view of a portion of the battery module 1. The battery module 1 includes an outer case 2 (package), a battery main body 10 (see FIG. 2), and a circuit board 20 (see FIG. 2). In the battery module 1, the battery main body 10 and the circuit board 20 are housed inside the outer case 2. The battery module 1 according to this embodiment is connected to a separately provided master controller 3 via a wireless communication unit incorporated in the circuit board 20 so as to be able to communicate wirelessly.

[0011] (Configuration of Exterior Case 2) As shown in Fig. 2, the exterior case 2 includes an upper case 2A disposed on the +Y side of the battery main body 10, a lower case 2B disposed on the -Y side of the battery main body 10, end plates 2C disposed on the -±Z sides of the battery main body 10, and side plates 2D disposed on the ±X sides of the battery main body 10 via a circuit board 20. The joining of the upper case 2A and the end plates 2C and the joining of the lower case 2B and the end plates 2C are not particularly limited, and examples include joining using fastening members such as screws, joining using an adhesive, welding, etc. The side plates 2D are positioned to cover the circuit board 20 after joining tabs 12 extending from the battery main body 10 to the circuit board 20, and are joined to the upper case 2A, the lower case 2B, and the end plates 2C.

[0012] (Configuration of Battery Main Body 10) As shown in FIG. 2 , the battery main body 10 is composed of multiple battery cells 11 stacked in the Z direction (second direction in the present disclosure). While detailed illustration of the battery cells 11 is omitted, the battery cells 11 are stacked together, including a positive electrode collector, a positive electrode layer, an electrolyte layer, a negative electrode layer, and a negative electrode collector, and are configured by laminating them together with a laminate film, for example. Each battery cell 11 includes a tab 12 extending in the X direction (first direction in the present disclosure), for example. Power is input and output to and from the battery cell 11 via the tab 12. As shown in FIG. 2 , these tabs 12 are formed in the shape of a flat thin plate extending in the XY direction and extend in the X direction. In this embodiment, the ±X sides are exemplified as the extension directions of the tabs 12 extending from the battery cells 11. In this case, for example, a configuration in which the positive electrode tab extends to the +X side and the negative electrode tab extends to the −X side can be exemplified. On the other hand, the direction in which the tabs 12 are pulled out is not limited to this, and both the positive and negative electrode tabs may be pulled out on the +X side. Alternatively, the positive electrode tab may be pulled out on the +X side and the negative electrode tab may be pulled out on the +Y side. In this case, circuit boards 20 are provided on the +X side and +Y side of the battery main body 10, which are the pulling directions of the tabs 12.

[0013] (Configuration of Circuit Board 20) FIG. 3 is a plan view showing a schematic configuration of the circuit board 20. FIG. 4 is a cross-sectional view of the circuit board 20 cut along line A-A in FIG. 3. Note that while the circuit board 20 arranged on the +X side of the battery main body 10 is described here as an example, the same applies to a circuit board 20 arranged on the -X side of the battery main body 10. The circuit board 20 includes, for example, engaging pieces 20A protruding toward the ±Z sides, and is positioned by engaging the engaging pieces 20A with engaging holes 2E provided in the end plates 2C. After joining the tabs 12 to the circuit board 20, the side plates 2D are joined to the upper case 2A, lower case 2B, and end plates 2C to secure the circuit board 20.

[0014] The circuit board 20 includes a substrate 21 on which a circuit pattern 215 is formed, and a plurality of openings 22 are formed in the substrate 21. As shown in Fig. 3, the openings 22 are formed longitudinally in the Y direction. These openings 22 are provided at positions facing the tabs 12 of the battery main body 10, respectively.

[0015] Furthermore, a plurality of bus bars 23, which are conductive members according to the present disclosure, are arranged on the base material 21 of the circuit board 20. As shown in FIG. 3 , each bus bar 23 is formed longitudinally in the Y direction, and a portion of an end face parallel to the Y direction faces the opening 22. In other words, a portion of the ±Z side end face of each bus bar 23 faces the opening 22 and constitutes a first opening side face 231 according to the present disclosure, which is one side face of the opening 22. The ±Y side ends of each bus bar 23 are embedded in the base material 21, thereby fixing the bus bar 23 to the base material 21.

[0016] FIG. 5 is an enlarged cross-sectional view of the busbar 23 and its vicinity on the circuit board 20 in FIG. 4 . As shown in FIG. 5 , a first opening side surface 231 of the busbar 23 has a groove 232 elongated in the Y direction along the opening 22 from the surface opposite the battery main body 10 (the surface on the +X side in the figure). In a cross section in the XZ plane shown in FIG. 5 , the groove 232 has a tapered surface (tapered surface 232A) that slopes away from the battery main body 10 as it moves away from the opening 22. In the example shown in FIG. 5 , the tapered surface 232A is an inclined flat surface, but it may also be formed as a curved surface. Therefore, the first opening side surface 231 of the busbar 23 is composed of an abutment surface 231A parallel to the XY plane and the tapered surface 232A.

[0017] On the other hand, the second opening side surface 211 facing the first opening side surface 231 of the opening 22 is formed of the base material 21. A fixing member 24 elongated in the Y direction is arranged on the base material 21 along the second opening side surface 211. In this embodiment, the fixing member 24 is a biasing member that biases the tab 12 inserted into the opening 22 toward the bus bar 23, and more specifically, is formed of a leaf spring.

[0018] FIG. 6 is a perspective view of the fixing member 24 of this embodiment. As shown in FIGS. 4 and 6 , the fixing member 24 of this embodiment includes a base end 241 extending from the circuit board 20 toward the −X side (toward the battery main body 10), an extension portion 242 extending from the tip side of the base end 241 toward the first opening side surface 231 of the opening 22, and a tip end 243 extending from the tip side of the extension portion 242 to the side opposite the first opening side surface 231. The base end 241 includes a plate-shaped insertion piece 241A protruding toward the +X side at the +X side end. Furthermore, an insertion hole 212 is formed in the base material 21 of the circuit board 20 along the second opening side surface 211 of the opening 22. The fixing member 24 is fixed to the circuit board 20 by inserting the insertion piece 241A into the insertion hole 212.

[0019] The extension portion 242 is curved and folded back from the tip side of the base end portion 241 toward the first opening side surface 231. The tip portion of the extension portion 242 is bent away from the first opening side surface 231 as it approaches the +X side, forming a tip portion 243. In this embodiment, the tab 12 is sandwiched between a bent corner portion 244 between the extension portion 242 and the tip portion 243 and the first opening side surface 231 of the bus bar 23.

[0020] Furthermore, the fixing member 24 in this embodiment is a leaf spring, and in a state before the tab 12 is inserted, the distance between the bent corner portion 244 and the first opening side surface 231 is less than the thickness of the tab 12 in the Z direction, or the bent corner portion 244 and the first opening side surface 231 are in contact with each other. Therefore, when the tab 12 is inserted between the bent corner portion 244 and the first opening side surface 231, the extension portion 242 is displaced in a direction away from the first opening side surface 231, and the resulting reaction force causes the fixing member 24 to urge the tab 12 toward the first opening side surface 231 of the bus bar 23. As a result, the tab 12 comes into surface contact with the bus bar 23, and is positioned.

[0021] As described above, the tip portion 243 of the fixing member 24 is formed by being bent so as to move away from the first opening side surface 231 as it moves toward the +X side. Therefore, as shown in FIG. 5 , the distance (distance in the Z direction) between the tip portion 243 of the fixing member 24 and the tapered surface 232A of the first opening side surface 231 of the bus bar 23 increases (expands) as it moves toward the +X side. In this embodiment, the tab 12 is inserted along the abutment surface 231A of the first opening side surface 231 of the bus bar 23. As a result, the tab 12 is inserted between the tip portion 243 of the fixing member 24 and the tapered surface 232A of the bus bar 23. In other words, gaps are provided between the tapered surface 232A and the tab 12 and between the tip portion 243 and the tab 12. In this embodiment, the tab 12 and the bus bar 23 are joined together by filling the space between the tab 12 and the tapered surface 232A with brazing material 25 (joining member). It is preferable to use a conductive material having a lower melting point than the tabs 12 and the bus bars 23 as the brazing material 25, which suppresses the generation of intermetallic compounds.

[0022] Furthermore, the fixing member 24 of this embodiment is provided with a plurality of slits 245 extending from the extension portion 242 to the tip portion 243. Therefore, the extension portion 242 and the tip portion 243 of one fixing member 24 are divided into a plurality of partial spring portions 246 by the plurality of slits 245. This allows the tab 12 to be evenly biased toward the bus bar 23, allowing the tab 12 to be properly brought into close contact with the contact surface 231A of the bus bar 23. In other words, if the slit 245 is not provided, the tab 12 would be biased toward the bus bar 23 by a single bent corner portion 244 elongated in the Y direction. If the insertion direction of the tab 12 is inclined or the thickness of the tab 12 is uneven, the biasing force biasing the tab 12 toward the bus bar 23 will be uneven, and there is a possibility that some parts of the tab 12 will have low contact with the contact surface 231A. For example, if the thickness of tab 12 on the +Y side is greater than the thickness on the −Y side, the force with which fixing member 24 urges tab 12 toward bus bar 23 is smaller on the −Y side than on the +Y side.

[0023] In contrast, in this embodiment, the fixing member 24 is divided into a plurality of partial spring portions 246 by the slits 245, and each of the partial spring portions 246 independently urges the tab 12 toward the bus bar 23. Therefore, even if the insertion direction of the tab 12 is inclined or the thickness of the tab 12 is not uniform, the tab 12 can be urged toward the bus bar 23 evenly across the Y direction, and the tab 12 can be more appropriately brought into close contact with the bus bar 23.

[0024] Furthermore, the provision of the slits 245 increases the surface area of ​​the fixing member 24. This improves the heat dissipation performance of the fixing member 24, making it possible to suppress temperature increases in the circuit board 20 and the battery cells 11.

[0025] FIG. 7 is a diagram illustrating an example of a method for joining tabs 12 to a circuit board 20. In this embodiment, for example, as shown in FIG. 7 , a first jig 81 having a width in the Z direction that is the same or approximately the same as that of the bus bar 23 is disposed on the −X side of the bus bar 23. Furthermore, a second jig 82, whose gap (distance in the Z direction) between itself and the first jig 81 is the thickness of the tab 12 or slightly larger than the thickness of the tab 12, is disposed on the −X side of the fixing member 24, between adjacent first jigs 81 in the Y direction. These first and second jigs 81 and 82 may be integrally configured, and may be formed in a comb-like shape with multiple gaps (gaps through which the tabs 12 are inserted) between the first and second jigs 81 and 82. In this case, the first and second jigs 81 and 82 can be inserted from the +Y side or the −Y side of the circuit board 20 and installed on the circuit board 20. Furthermore, after joining the tabs 12 to the bus bar 23, the first and second jigs 81 and 82 can be easily removed along the Y direction.

[0026] In this embodiment, the engagement pieces 20A of the circuit board 20 engage with the engagement holes 2E provided in the end plate 2C to position the circuit board 20 on the +X side of the battery main body 10. At this time, the tabs 12 of the battery cells 11 are positioned on an extension of the first opening side surface 231 on the -X side. This allows the tabs 12 to be easily inserted between the first jig 81 and the second jig 82. As a result, the tip of the tab 12 is guided along the extension portion 242 of the fixing member 24 to the abutment surface 231A of the bus bar 23. By pressing the tab 12, the extension portion 242 of the fixing member 24 is displaced away from the bus bar 23, and the tab 12 enters between the abutment surface 231A of the bus bar 23 and the bent corner portion 244 of the fixing member 24. The biasing force of the fixing member 24 also causes the tab 12 to be tightly attached to the abutment surface 231A.

[0027] Thereafter, the brazing material 25 is filled into the groove 232 of the bus bar 23 to join the bus bar 23 and the tab 12. By filling the groove 232 with the brazing material 25, the brazing material 25 does not protrude from the +X side surface of the circuit board 20 to the +X side, thereby enabling space saving.

[0028] Another method involves irradiating the groove 232, which is the portion filled with the brazing material 25, with laser light when joining the tab 12 and the bus bar 23 with the brazing material 25. In this method, to properly melt the brazing material 25, it is preferable to irradiate the laser light from, for example, a normal direction, to match the surface shape of the groove 232. Here, if the groove 232 is formed, for example, in a generally L-shape having a flat portion perpendicular to the abutment surface 231A and an orthogonal portion perpendicular to the flat portion, the laser light is irradiated in a direction perpendicular to the flat portion (thickness direction of the circuit board 20). In this case, depending on the irradiation angle of the laser light, the laser light that penetrates the opening 22 may be irradiated onto the battery cell 11 and damage the battery cell 11. In other words, in this embodiment, the biasing force of the fixing member 24 tightly contacts the tab 12 with the bus bar 23. However, a gap may also be formed between the tab 12 and the bus bar 23, for example, at the position where the slit 245 is provided. There is also a risk that laser light may be irradiated onto the battery cell 11 through the slits 245 of the fixing member 24 .

[0029] In contrast, in this embodiment, the groove 232 is formed in a container shape with a tapered surface 232A. In this case, the irradiation angle of the laser light can be set so that it is approximately along the normal direction of the tapered surface 232A, which increases the degree of freedom in the irradiation angle of the laser light. In other words, the laser light can be irradiated from a direction that is inclined relative to the thickness of the circuit board 20, which prevents the laser light from penetrating the opening 22 and reaching the battery cell 11.

[0030] Furthermore, the amount of filler material 25 required to fill the groove 232 can be reduced compared to when the groove 232 is made approximately L-shaped, which makes it possible to reduce costs and shorten the time required for joining using the solder material 25.

[0031] Returning to FIG. 3 , other components of the circuit board 20 of this embodiment will be described. The circuit board 20 of this embodiment has a base material 21 on which multiple electronic components (electronic chips 213) and a wireless communication chip 214 are disposed. The electronic chip 213 is an IC chip constituting a battery monitoring system, and examples thereof include a temperature measurement chip 213A (temperature measurement unit) for measuring the temperature of each battery cell 11 and a voltage adjustment chip 213B (voltage adjustment unit) for controlling and managing the charge / discharge rate of each battery cell 11. Other battery components may also include other electronic chips, such as a state-of-charge measurement chip for measuring the state of charge of the battery main body 10 and a control chip for controlling the operation of the multiple electronic chips. These electronic chips 213 are connected to the bus bars 23 via, for example, circuit patterns 215 formed on the base material 21.

[0032] In this embodiment, a wireless communication chip 214 is disposed on the base material 21 of the circuit board 20. The wireless communication chip 214 is connected to, for example, the electronic chips 213, and transmits information obtained by each electronic chip 213 to the master controller 3 via wireless communication. The wireless communication chip 214 may also receive a predetermined command signal from the master controller 3 and output the command signal to each electronic chip 213. Examples of such command signals include command values ​​for starting and ending charging and discharging of the battery cells 11, and the amount of charging and discharging.

[0033] [Effects of the Present Embodiment] The battery module 1 of the present embodiment includes a battery main body 10 and a circuit board 20. The battery main body 10 includes battery cells 11 with tabs 12 extending in the X direction, and multiple battery cells 11 are stacked in the Z direction. The circuit board 20 is disposed facing the +X side of the battery main body 10. The circuit board 20 is provided with an opening 22 penetrating in the X direction, and the opening 22 has a first opening side surface 231 and a second opening side surface 211 that face each other in the Z direction. The circuit board 20 is provided with a bus bar 23, which is a conductive member, and the bus bar 23 is disposed along the opening 22, and the side surface of the bus bar 23 forms the first opening side surface 231 of the opening 22. The circuit board 20 is also provided with a fixing member 24, which is disposed along the second opening side surface 211 of the opening 22. The tab 12 extending from the battery cell 11 to the +X side is inserted into the opening 22 of the circuit board 20 , and is sandwiched between the bus bar 23 and the fixing member 24 and joined to the bus bar 23 .

[0034] In this configuration, the bus bar 23 provided on the circuit board 20 and the tab 12 are joined in close contact, eliminating the need for separate wiring to connect the battery main body 10 and the circuit board 20, thereby facilitating miniaturization of the battery module 1. In other words, the circuit board 20 on which multiple electronic chips 213 functioning as a battery monitoring system are mounted can be incorporated into the battery module 1. This allows for a more compact battery module 1 compared to a conventional configuration in which the battery main body and a circuit board having a battery monitoring system are connected by wiring. Furthermore, because the tab 12 is sandwiched between the bus bar 23 and the fixing member 24, the tab 12 is positioned in a state in which the tab 12 is in close contact with the bus bar 23. This eliminates the need for a machining jig for tightly positioning the tab 12 and the bus bar 23, thereby reducing the operating costs of the joining process.

[0035] In the battery module 1 of this embodiment, a concave groove 232 is provided along the first opening side surface 231 on the +X side surface of the bus bar 23 (the surface opposite the battery cells 11), and a brazing material 25 (jointing member) that joins the tab 12 and the bus bar 23 is filled in the groove 232. As a result, when the tab 12 and the bus bar 23 are joined with the brazing material 25, the brazing material 25 fits within the groove 232. In other words, the brazing material 25 does not bulge convexly on the +X side of the circuit board 20 or the bus bar 23, which can cause problems such as space compression in the battery module 1.

[0036] In this embodiment, the groove 232 has a tapered surface 232A that slopes toward the +X side as it moves away from the opening 22. In this case, when using a joining method using laser irradiation, the laser irradiation angle can be set to be approximately normal to the tapered surface 232A, thereby improving the flexibility of the laser irradiation angle. This increased flexibility in the laser irradiation angle allows the laser beam to be irradiated from a direction that is inclined relative to the thickness of the circuit board 20, thereby preventing the laser beam from penetrating the opening 22 and reaching the battery cell 11. Furthermore, compared to when the groove 232 is approximately L-shaped, the volume between the groove 232 and the tab 12 is smaller, allowing for a reduced amount of brazing material 25 to be filled into the groove 232. This reduces the cost of the brazing material 25 and the time required for the joining process using laser irradiation.

[0037] In the battery module 1 of this embodiment, a temperature measurement chip 213A for measuring temperature and a voltage adjustment chip 213B, which is an electronic component for adjusting voltage, are arranged on the circuit board 20, and the bus bar 23 is electrically connected to the temperature measurement chip 213A and the voltage adjustment chip 213B via the circuit pattern 215. This makes it possible to incorporate a battery monitoring system having a temperature measurement chip and a voltage adjustment chip, which has conventionally been configured separately from the battery main body 10, into the circuit board 20. Therefore, as described above, wiring connection between the battery main body 10 and the battery monitoring system is not required, and the battery module 1 can be made smaller.

[0038] In the battery module 1 of this embodiment, the fixing members 24 are biasing members that bias the tabs 12 toward the bus bars 23. This allows the tabs 12 to be brought into close contact with the bus bars 23, ensuring appropriate electrical continuity between the tabs 12 and the bus bars 23. Furthermore, the tabs 12 and the bus bars 23 can be joined without using a separate jig for bringing the bus bars 23 and the tabs 12 into close contact, thereby reducing the manufacturing cost of the battery module 1. In other words, it is no longer necessary to prepare multiple processing jigs, and the time cost associated with the joining process can also be shortened.

[0039] In the battery module 1 of this embodiment, the fixing member 24 is provided with multiple slits 245. This increases the surface area of ​​the fixing member 24, improving heat dissipation performance. This allows the battery cells 11 and the circuit board 20 to be cooled effectively. Furthermore, by providing multiple slits 245, the fixing member 24 is divided into multiple partial spring portions 246 along the Y direction, and each partial spring portion 246 can evenly bias the tab 12 against the bus bar 23. This allows the tab 12 to be more appropriately attached to the bus bar 23.

[0040] In the battery module 1 of this embodiment, when the circuit board 20 is positioned facing the side surface of the battery body 10, the tabs 12 of the battery cells 11 are disposed on the −X side of the first opening side surface 231 of the bus bar 23. This makes it possible to easily guide the tabs 12 to the first opening side surface 231 of the bus bar 23. This makes it easy to position the tabs 12 and the bus bar 23, thereby reducing the time and cost involved in the joining process.

[0041] Second Embodiment Next, a second embodiment will be described. In the first embodiment, an example was shown in which one tab 12 was inserted between the bus bar 23 and the fixing member 24. In contrast, the second embodiment differs from the first embodiment in that a plurality of tabs 12 are stacked and inserted between the bus bar 23 and the fixing member 24.

[0042] Figure 8 is an enlarged cross-sectional view of the vicinity of the bus bar 23 of the circuit board 20 in this embodiment. In this embodiment, as in the first embodiment, the battery module 1 includes a battery main body 10 and a circuit board 20, and the battery main body 10 and the circuit board 20 are housed in an exterior case 2. In this embodiment, as shown in Figure 8, a plurality of tabs 12 extending from the battery cells 11 to the +X side are stacked in the Z direction, inserted into openings 22 of the circuit board 20, and clamped between the bus bar 23 and the fixing member 24. This embodiment shows an example in which three tabs 12 are stacked, but this is not limited thereto, and two tabs 12, or four or more tabs 12 may also be stacked.

[0043] More specifically, the multiple tabs 12 are stacked such that the tab tip edges 121 are positioned at different positions in the X direction. It is preferable that the multiple tabs 12 are stacked such that the tab tip edges 121 are positioned closer to the +X direction as they move away from the bus bar 23. This increases the contact area of ​​the brazing material 25 with each tab 12 when filling the grooves 232 with the brazing material 25, thereby increasing the bonding strength. Furthermore, the stacked tabs 12 are biased toward the bus bar 23 by the bent corners 244 of the fixing member 24. Therefore, the stacked tabs 12 come into contact with each other at the bent corners 244, and the tab 12 closest to the bus bar 23 abuts against the bus bar 23. Meanwhile, gaps may occur between the tabs 12 at positions shifted from the bent corners 244 of the tabs 12. Here, the brazing material 25 penetrates into the gaps between the tabs 12 by capillary action. Therefore, the tabs 12 are firmly joined together by the brazing material 25 .

[0044] [Effects of the Present Embodiment] In the battery module 1 of the present embodiment, multiple tabs 12 are stacked in the Z direction and inserted into a single opening 22. The tab tip edges 121 of the multiple tabs 12 are positioned differently in the X direction and are sandwiched between the fixing member 24 and the bus bar 23. This allows multiple tabs 12 to be joined to the bus bar 23 together, thereby reducing the number of joining operations (the number of steps) and the time required for joining compared to joining each individual tab 12 to the bus bar 23 individually. Furthermore, because multiple tabs 12 are inserted into a single opening 22 together, the number of openings 22 can be reduced, simplifying the configuration of the circuit board 20. Furthermore, by shifting the positions of the tab tip edges 121 in the X direction, the surface area of ​​the tabs 12 that contact the brazing material 25 is increased, thereby improving joining strength compared to when the positions of the tab tip edges 121 of adjacent tabs 12 are aligned in the X direction. In particular, in this embodiment, the positions of the tab tip edges 121 are shifted in the direction away from the battery cell 11 (toward the +X side in this embodiment) with increasing distance from the bus bar 23. In this case, the surface of each tab 12 facing the bus bar 23 (the surface on the -Z side in the example of FIG. 8 ) faces the groove 232 of the bus bar 23. As a result, when molten brazing material 25 is filled into the groove 232 of the bus bar 23, the brazing material 25 can be brought into contact with each tab 12, thereby suitably joining each tab 12 and the bus bar 23. Furthermore, because the surface of each tab 12 faces the brazing material 25 filled in the groove 232, the brazing material 25 can enter between the tabs 12 through the gaps between the tabs 12 due to capillary action, thereby improving the joining strength.

[0045] [Modifications] The present invention is not limited to the above-described embodiment, and includes the following modifications within the scope of achieving the object of the present invention.

[0046] [Variation 1] In the above embodiment, the X direction is used as an example of the first direction in the present disclosure, and the tab 12 is pulled out from the battery cell 11 to the +X side. However, as described above, the pull-out direction of the tab 12 is not limited to the +X side. For example, in the above embodiment, the tab 12 also extends from the battery cell 11 to the -X side, and a circuit board 20 with a similar configuration to that on the +X side is provided on the -X side of the battery main body 10 correspondingly. The extension direction of the tab 12 may also be the Y direction. When the tab 12 extends to the +Y side, a circuit board 20 with a similar configuration to that on the +Y side of the battery main body 10 may be disposed between the upper case 2A and the battery main body 10. When the tab 12 extends to the -Y side, a circuit board 20 with a similar configuration to that on the -Y side of the battery main body 10 may be disposed between the lower case 2B and the battery main body 10.

[0047] [Variation 2] In the above embodiment, the configuration in which groove 232 having tapered surface 232A is provided on first opening side surface 231 of busbar 23 has been described as an example, but this is not limiting. For example, groove 232 may be shaped as a substantially L-shape having a flat portion perpendicular to abutment surface 231A and an orthogonal portion perpendicular to the flat portion. Even in this case, brazing material 25 can be filled between groove 232 and tab 12 to connect tab 12 and busbar 23.

[0048] Note that groove 232 is not an essential component of the present disclosure, and for example, groove 232 may not be provided in bus bar 23. In this case, brazing material 25 is joined in a convex shape on the +X side of bus bar 23, so a gap is required between circuit board 20 and side plate 2D compared to the above embodiment. However, this can contribute to space savings compared to when the circuit board is disposed externally and connected by wiring.

[0049] [Variation 3] In the above embodiment, the fixing member 24 is exemplified as a leaf spring including a base end 241 extending from the base material 21 of the circuit board 20 toward the −X side, an extension portion 242 curved from the tip of the base end 241 toward the first opening side surface 231, and a tip end portion 243 extending from the tip side of the extension portion 242 to the side opposite the first opening side surface 231. However, the fixing member 24 as described above is merely an example, and other configurations may also be used. For example, the fixing member 24 may be a leaf spring in which the base end 241 extends from the circuit board 20 toward the +X side. Furthermore, the tip end portion 243 may not be provided, and the tip of the extension portion 242 may bias the tab 12 toward the bus bar 23. Furthermore, the fixing member 24 may be configured to bias the tab 12 toward the bus bar 23. For example, one end of an elastic member such as a coil spring or rubber may be fixed to the second opening side surface 211, and the other end may have an abutment piece that abuts against the tab 12, and the tab 12 may be biased toward the bus bar 23 by the elastic force of the coil spring or elastic member.

[0050] Furthermore, the fixing member 24 is not limited to a biasing member that biases the tab 12 toward the bus bar 23 by elastic force. The fixing member 24 may be configured to be able to clamp the tab 12 between itself and the bus bar 23. For example, the fixing member 24 may be configured to include a fixing piece that faces the first opening side surface 231 and an advancing / retracting mechanism that moves the fixing piece forward and backward in the Z direction. In this case, the fixing piece may be moved to a position where the distance between the fixing piece and the first opening side surface 231 is slightly smaller than the thickness of the tab 12 in the Z direction, and the tab 12 may be clamped by being press-fitted between the fixing piece and the first opening side surface 231. Alternatively, the tab 12 may be clamped by inserting the tab 12 into the opening 22 and then moving the fixing piece toward the first opening side surface 231.

[0051] [Modification 4] While the configuration in which a plurality of slits 245 are provided in the fixing member 24 and one fixing member 24 is divided into a plurality of partial spring portions 246 has been exemplified, the present invention is not limited to this. For example, a configuration in which a plurality of fixing members 24 are arranged side by side in the Y direction at a predetermined interval for one opening may also be used. Even in this case, the same effects as those of the above embodiment can be achieved.

[0052] In the above embodiment, the brazing material 25 that joins the tab 12 and the bus bar 23 is filled in the groove 232 of the bus bar 23 to join the tab 12 and the bus bar 23. However, the brazing material 25 may also be filled between the tab 12 and the fixing member 24 (for example, between the tip 243 of the fixing member 24 and the tab 12).

[0053] 1...battery module, 2...outer case, 10...battery body, 11...battery cell, 12...tab, 20...circuit board, 21...substrate, 22...opening, 23...bus bar (conductive member), 24...fixing member, 25...soldering material, 211...second opening side, 213...electronic chip, 213A...temperature measurement chip, 213B...voltage adjustment chip, 214...wireless communication chip, 215...circuit pattern, 231...first opening side, 231A...contact surface, 232...groove portion, 232A...tapered surface

Claims

1. A battery module comprising: a battery body in which a plurality of battery cells, each having a tab extending in a first direction, are stacked in a second direction perpendicular to the first direction; and a circuit board arranged opposite the battery body in the first direction, wherein the circuit board has an opening penetrating in the first direction, the opening having a first opening side surface and a second opening side surface opposing each other in the second direction, the circuit board comprising a conductive member constituting the first opening side surface of the opening, and a fixing member arranged along the second opening side surface of the opening and fixing the tab, wherein the tab is inserted into the opening, sandwiched between the conductive member and the fixing member, and joined to the conductive member.

2. The battery module according to claim 1, wherein the conductive member has a recessed groove formed along the first opening side surface from the surface opposite the battery cell, and a joining material is filled in the groove to join the tab and the conductive member.

3. The battery module according to claim 2, wherein the groove has a tapered shape that slopes toward the surface opposite the battery cell as it moves away from the opening.

4. The battery module according to claim 1, wherein a plurality of said tabs are stacked and inserted into one of said openings, and the positions of the tab tip edges of the plurality of said tabs are different from each other in said first direction.

5. The battery module according to claim 1, wherein the circuit board is further provided with a temperature measuring unit, which is an electronic component for measuring temperature, and a voltage adjusting unit, which is an electronic component for adjusting voltage, and the conductive member on the circuit board is electrically connected to the temperature measuring unit and the voltage adjusting unit by a circuit pattern.

6. The battery module according to claim 1, wherein the fixing member is a biasing member that biases the tab toward the conductive member.

7. The battery module according to claim 1, wherein the fixing member has a plurality of slits.

8. The battery module according to claim 1, wherein, when the circuit board is placed opposite a side surface of the battery body, the tab of the battery cell is positioned on an extension line of the first opening side surface of the conductive member extended in the first direction.

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