Battery module

Abstract

A battery module 1 comprises a plurality of battery cells 10, a plurality of first electrically conductive plates 5, a plurality of second electrically conductive plates 7, and a plurality of connection wires 8. Each battery cell 10 has a first electrode (peripheral electrode 13) and a second electrode (central electrode 14). The plurality of battery cells 10 constitute a plurality of parallel units 16, each parallel unit 16 being composed of two or more battery cells 10 connected in parallel to each other. The plurality of first electrically conductive plates 5 cover the plurality of parallel units 16, and each of the first electrically conductive plates 5 is connected to the first electrodes of the battery cells 10 that constitute the corresponding parallel unit 16. The plurality of second electrically conductive plates 7 cover the plurality of first electrically conductive plates 5, and each of the second electrically conductive plates 7 is connected to the second electrodes of the battery cells 10 that constitute the corresponding parallel unit 16. The plurality of connection wires 8 connect each of the plurality of second electrically conductive plates 7 to an adjacent first electrically conductive plate 5 so as to sequentially connect the parallel units 16 in series.

Description

Battery module

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

[0002] Patent Document 1 discloses a battery pack including a plurality of first conductive plates arranged to cover a number of battery cells, and a plurality of second conductive plates arranged to cover the plurality of first conductive plates. The number of battery cells is divided into a plurality of parallel units. In each parallel unit, a plurality of battery cells are connected in parallel with each other. The plurality of parallel units are sequentially connected in series. In order to electrically connect such a number of battery cells, the plurality of first conductive plates and the plurality of second conductive plates are arranged in a staggered pattern. Each conductive plate covers two adjacent parallel units. Each conductive plate is connected to the positive electrodes of the battery cells constituting one parallel unit, and is also connected to the negative electrodes of the battery cells constituting the other parallel unit.

[0003] U.S. Patent No. 11,515,598

[0004] In the above configuration, each conductive plate is large.

[0005] An object of the present disclosure is to provide a battery module with improved handling properties of the conductive plates.

[0006] One aspect of the present disclosure is a plurality of battery cells constituting a plurality of parallel units, wherein each of the parallel units consists of two or more of the battery cells connected in parallel with each other, and each of the battery cells has a first electrode and a second electrode with different polarities from each other; a plurality of first conductive plates covering each of the plurality of parallel units, wherein each of the first conductive plates is connected to the first electrodes of the two or more battery cells constituting the corresponding parallel unit; a plurality of second conductive plates covering each of the plurality of first conductive plates, wherein each of the second conductive plates is connected to the second electrodes of the two or more battery cells constituting the corresponding parallel unit; and a plurality of connection lines for sequentially connecting the plurality of parallel units in series by connecting each of the plurality of second conductive plates to the adjacent first conductive plate.

[0007] According to the present invention, a battery module with improved handling of conductive plates can be provided.

[0008] A perspective view of a battery module according to the first embodiment. An exploded perspective view of the battery module shown in Figure 1. An exploded perspective view showing a magnified portion of the battery module shown in Figure 1. A perspective view of the cell holder of the battery module shown in Figure 1, viewed from the insertion side. A schematic diagram of the current collection structure of the battery module shown in Figure 1. A perspective view showing the first conductive plate and the second conductive plate of the battery module shown in Figure 3. A plan view showing the state in which the first lead plate is laminated on the outer surface of the cell holder of the battery module shown in Figure 1. A plan view showing the state in which the first current collection plate is further laminated from the state shown in Figure 7A. A plan view showing the state in which an insulating layer is further laminated from the state shown in Figure 7B. A plan view showing the state in which the second lead plate is further laminated from the state shown in Figure 7C. A plan view showing the state in which the second current collection plate is further laminated from the state shown in Figure 7D, i.e., a part of the battery module shown in Figure 1. A partial cross-sectional view of the battery module shown by cutting along the line A-A in Figure 7E. A magnified portion of Figure 8. A perspective view showing a part of the battery module according to the second embodiment. An exploded perspective view showing a part of the battery module shown in Figure 10.

[0009] A battery module according to one embodiment of the present disclosure comprises a plurality of battery cells constituting a plurality of parallel units, each of which consists of two or more battery cells connected in parallel with each other, each of which has a first electrode and a second electrode with opposite polarity; a plurality of first conductive plates covering each of the plurality of parallel units, each of which is connected to the first electrode of the two or more battery cells constituting the corresponding parallel unit; a plurality of second conductive plates covering each of the plurality of first conductive plates, each of which is connected to the second electrode of the two or more battery cells constituting the corresponding parallel unit; and a plurality of connecting lines connecting each of the plurality of second conductive plates to the adjacent first conductive plate in order to sequentially connect the plurality of parallel units in series.

[0010] According to the above configuration, the first conductive plate covers a parallel unit consisting of two or more battery cells to be connected in parallel, and is connected to the first electrode of the battery cells constituting this parallel unit. The second conductive plate covers the first conductive plate and also covers the parallel unit that is covered by it. The second conductive plate is connected to the second electrode of the battery cell constituting this parallel unit, and is also connected to the adjacent first conductive plate via a connecting wire. As a result, parallel connection of two or more battery cells is realized within each parallel unit, and series connection of multiple parallel units is realized.

[0011] The first and second conductive plates only need to be sized to cover one parallel unit. Therefore, the conductive plates can be miniaturized. This also makes it easier to position and assemble the conductive plates. Furthermore, compared to the case where the conductive plates are arranged to span two parallel units, the first and second conductive plates can be assembled and disassembled for each parallel unit. As a result, the handling of the conductive plates is improved.

[0012] In a battery module according to another embodiment of the present disclosure, a second conductive plate may be integrally provided with connecting wires, and the first conductive plate may have tabs connected to the connecting wires.

[0013] This allows the connecting wires to be attached to the first conductive plate simultaneously when the second conductive plate is assembled to the first conductive plate and the battery cell, thereby improving productivity.

[0014] In a battery module according to another embodiment of the present disclosure, the tab may be positioned between two adjacent battery cells.

[0015] This prevents interference between the series connection structure and the parallel connection structure within the parallel unit, thus preventing unwanted short circuits. Furthermore, the series connection structure is positioned to effectively utilize the space between battery cells, contributing to the overall miniaturization of the battery module.

[0016] A battery module according to another embodiment of the present disclosure may further include a cell holder that holds a plurality of battery cells and on which a first conductive plate is stacked, and a fastening structure that, with the cell holder, tabs, and connecting wires stacked in order, removably fastens the connecting wires and tabs to the cell holder.

[0017] This allows for easy installation and disassembly of conductive plates on a parallel unit basis.

[0018] A battery module according to another embodiment of the present disclosure may further include a cell holder that holds a plurality of battery cells and on which a first conductive plate is stacked; an insulating layer interposed between the first conductive plate and a second conductive plate; and at least one of a first positioning structure for positioning the first conductive plate with respect to the cell holder, a second positioning structure for positioning the second conductive plate with respect to the insulating layer, and a third positioning structure for positioning the insulating layer with respect to the cell holder.

[0019] This improves the positional accuracy of the multiple battery cells, the first conductive plate, the insulating layer, and the second conductive plate. The reliability of the connection between the first conductive plate and the first electrode, the reliability of the connection between the second conductive plate and the second electrode, and the reliability of the connection between the first conductive plate and the second conductive plate via the connecting wire are also improved.

[0020] In a battery module according to another embodiment of the present disclosure, the first conductive plate includes a first lead plate having first lead wires connected to a first electrode, and a first current collector plate superimposed on the first lead plate, wherein the first current collector plate may have a greater thickness than the first lead plate.

[0021] This ensures sufficient overall thickness of the first conductive plate, allowing for the passage of large currents. Furthermore, it makes it possible to reduce the thickness of the first lead plate. The elasticity of the first lead wire is ensured, improving the ease of assembly and connection reliability of the first lead wire to the first electrode.

[0022] In a battery module according to another embodiment of the present disclosure, the second conductive plate includes a second lead plate having a second lead wire connected to a second electrode, and a second current collector plate superimposed on the second lead plate, wherein the second current collector plate may have a greater thickness than the second lead plate.

[0023] This makes it possible to increase the amount of current that can flow through the second conductive plate and to ensure the elasticity of the second lead wire, in the same manner as described above.

[0024] In a battery module according to another embodiment of the present disclosure, the first conductive plate may have tabs connected to connecting wires, and the connecting wires may be integrally provided with the second lead plate.

[0025] This ensures the elasticity of the connecting wires, improving their ease of assembly to the tabs and the reliability of the connections.

[0026] A battery module according to another embodiment of the present disclosure may further include an insulating layer interposed between a first conductive plate and a second conductive plate.

[0027] This prevents unwanted short circuits between the first conductive plate and the second conductive plate due to the presence of an insulating layer.

[0028] In a battery module according to another embodiment of the present disclosure, the first conductive plate has a first lead wire connected to a first electrode, the second conductive plate has a second lead wire connected to a second electrode, the insulating layer has an electrode opening that exposes the second electrode and allows the second lead wire to pass through, and the first lead wire may be covered by the peripheral edge of the electrode opening of the insulating layer.

[0029] This allows the second conductive plate to be laminated onto the insulating layer, while the first lead wire is hidden by the insulating layer. This prevents the second conductive plate from being unintentionally connected to the first lead wire.

[0030] In a battery module according to another embodiment of the present disclosure, a second conductive plate may be integrally provided with connecting wires, the first conductive plate may have tabs connected to the connecting wires, and the insulating layer may have tab openings that expose the tabs and allow the connecting wires to pass through.

[0031] This makes it possible to create a structure in which parallel units are connected in series with connecting wires, even if an insulating layer is interposed between the first conductive plate and the second conductive plate.

[0032] In a battery module according to another embodiment of the present disclosure, the first electrode may be provided on the periphery of the battery cell, and the second electrode may be provided in the central part of the battery cell.

[0033] Connecting a conductive plate to an electrode at its periphery is more difficult than connecting it to a central electrode. In the above configuration, the first conductive plate is connected to a first electrode located at its periphery. The first conductive plate is positioned closer to the battery cell than the second conductive plate. Compared to the case where the first conductive plate is connected to the central electrode and the second conductive plate is connected to the periphery electrode, the difficulty of connecting the conductive plates to the electrodes can be reduced.

[0034] In a battery module according to another embodiment of the present disclosure, each battery cell is cylindrical, the first electrode and the second electrode are provided at the same end of the battery cell, and the plurality of battery cells may be arranged parallel to each other such that the ends on which the first electrode and the second electrode are provided face the first conductive plate.

[0035] This enables a single-sided current collection structure with improved handling of the conductive plate.

[0036] The following describes specific examples of this disclosure in detail based on the drawings. In the following description, terms indicating specific directions or positions (e.g., "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating understanding of the disclosure with reference to the drawings, and the meaning of these terms does not limit the technical scope of this disclosure. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components. Furthermore, the embodiments shown below are examples of the technical concept of this disclosure and do not limit this disclosure to them. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are intended to be illustrative, and not to limit the scope of this disclosure unless specifically stated. Also, the content described in one embodiment or example is applicable to other embodiments or examples. Furthermore, the size and positional relationships of the components shown in the drawings may be exaggerated for clarity in the explanation.

[0037] The battery module of this disclosure is applicable, for example, to emergency power sources such as backup battery units (BBUs) and to power the drive motors of electric vehicles. However, this disclosure does not specify the application of the battery module, and it can be used as a power source for various other electrical devices.

[0038] Referring to Figure 1, the battery module 1 according to the first embodiment comprises an outer case 2, a battery assembly 3, and a current collection structure 4.

[0039] The outer casing 2 is a long, rectangular parallelepiped composed of two case components that can be separated in the height direction Z. The outer casing 2 forms an internal space that houses the battery assembly 3 and the current collection structure 4. The current collection structure 4 is a so-called single-sided current collection structure, positioned only on one side in the height direction Z (upper side of the paper in Figure 1) relative to the battery assembly 3. Note that, in order to clearly show the current collection structure 4, the drawing shows only the case component on the other side in the height direction Z (lower side of the paper in Figure 1) of the two case components. When the battery module 1 is in use, one side in the height direction Z may be facing downwards.

[0040] When the battery module 1 is applied to the BBU, there are strict dimensional constraints in the width direction Y, which is perpendicular to both the longitudinal direction X and the height direction Z of the outer case 2. Despite these constraints, the dense arrangement of the battery assemblies 3 is achieved as described below.

[0041] The battery assembly 3 has a plurality of battery cells 10 and a cell holder 20.

[0042] Referring to Figures 2 and 3, each battery cell 10 is, for example, a lithium-ion secondary battery. The battery cell 10 is cylindrical, or more precisely, cylindrical in shape. However, the battery cell 10 is not limited to lithium-ion batteries, but may be other types of secondary batteries currently in use, or secondary batteries such as all-solid-state batteries that will be developed in the future. Also, the shape of the battery cell 10 is not limited to cylindrical, but may be rectangular.

[0043] Each battery cell 10 has an outer casing 11 and a sealing plate 12. The outer casing 11 is a bottomed cylindrical shape with an opening at one end in the axial direction. The sealing plate 12 is attached to the outer casing 11 via an insulating material and closes the opening of the outer casing 11. The outer casing 11 houses the electrode body and electrolyte and is sealed by the sealing plate 12.

[0044] Each battery cell 10 has a peripheral electrode 13 provided at its peripheral portion and a central electrode 14 provided at its central portion. The peripheral electrode 13 and the central electrode 14 are provided at the same-side ends in the axial direction of the battery cell 10. The peripheral electrode 13 is provided on the outer can 11, and the central electrode 14 is provided on the sealing plate 12. The peripheral electrode 13 and the central electrode 14 are insulated from each other by an insulating material between the outer can 11 and the sealing plate 12 and have different polarities from each other. As an example, the peripheral electrode 13 is the negative electrode and the central electrode 14 is the positive electrode, but the polarities may be reversed.

[0045] Referring to FIGS. 2 to 4, the cell holder 20 is made of an insulating material such as synthetic resin. The cell holder 20 integrally has a plurality of accommodating portions 21 for individually accommodating a plurality of battery cells 10.

[0046] Each accommodating portion 21 has a cylindrical shape with an inner diameter slightly larger than the outer diameter of the battery cell 10. The plurality of accommodating portions 21 are provided parallel to each other with their axial directions oriented in the height direction Z. The plurality of accommodating portions 21 are dense in the longitudinal direction X and the width direction Y. Each accommodating portion 21 is open at both axial ends. The insertion port 22 on one end side has a larger diameter than the central port 23 on the other end side.

[0047] The cell holder 20 has an outer surface 24 where a plurality of central ports 23 are open. The outer surface 24 is a flat surface orthogonal to the axial direction of the accommodating portion 21. Inside the accommodating portion 21, an annular inner bottom surface 25 that is the back surface of the outer surface 24 and surrounds the central port 23 is formed. The cell holder 20 has a through hole 26 that opens to the outer surface 24 and the inner bottom surface 25. The through hole 26 is, as an example, an elongated rectangular shape and is adjacent to the central port 23.

[0048] Each battery cell 10 is inserted into the corresponding housing portion 21 through the insertion port 22, becomes substantially coaxial with the housing portion 21, and stops being inserted by abutting against the inner bottom surface 25. The peripheral electrode 13 is partially exposed through the through hole 26. The central electrode 14 is exposed through the central port 23. The plurality of battery cells 10 are held by the cell holder 20 in a posture where the ends provided with the peripheral electrode 13 and the central electrode 14 are located at the back of the housing portion 21, and are arranged parallel to each other. The peripheral electrode 13 and the central electrode 14 of the battery cell 10 are exposed and aligned on the outer surface 24 side of the cell holder 20.

[0049] The plurality of battery cells 10 form a plurality of cell rows 15 arranged in the longitudinal direction X. In each cell row 15, the plurality of battery cells 10 are arranged in the width direction Y.

[0050] The plurality of battery cells 10 constitute a plurality of parallel units 16. Each parallel unit 16 is composed of two or more battery cells 10 connected in parallel to each other. The plurality of parallel units 16 are sequentially connected in series. Such electrical connection between the battery cells 10 is realized by the current collecting structure 4.

[0051] In the present embodiment, as a mere example, the battery assembly 3 has 99 battery cells 10. The 99 battery cells 10 form 33 cell rows 15, and 3 battery cells 10 form one cell row 15. The battery assembly 3 has 11 parallel units 16, and one parallel unit 16 is composed of 9 battery cells 10. Three cell rows 15 constitute one parallel unit 16. The 11 parallel units 16 are arranged in the longitudinal direction X.

[0052] Referring to FIG. 5, the current collecting structure 4 has a plurality of first conductive plates 5, an insulating layer 6, a plurality of second conductive plates 7, and a plurality of connection lines 8. Thus, the conductive plates of the current collecting structure 4 are of a two-layer type including the first conductive plate 5 and the second conductive plate 7. By adopting the two-layer type, various advantages such as an increase in the number of battery cells 10 forming the parallel unit 16, miniaturization in the width direction Y of the battery module 1, and improvement in the rigidity of the conductive plate can be obtained as compared with the single-layer type.

[0053] The insulating layer 6 is interposed between the first conductive plate 5 and the second conductive plate 7. The first conductive plate 5, the insulating layer 6, and the second conductive plate 7 are stacked in this order on the outer surface 24 of the cell holder 20. Multiple battery cells 10 are arranged parallel to each other such that the ends on which the peripheral electrodes 13 and central electrodes 14 are provided face the first conductive plate 5 in the height direction Z. Since both the first conductive plate 5 and the second conductive plate 7 have two layers, as will be described later, the current collection structure 4 can also be said to have five layers, including the insulating layer 6.

[0054] The number of first conductive plates 5 and second conductive plates 7 is the same as the number of parallel units 16 (for example, 11). Multiple first conductive plates 5 are arranged at the same position relative to each other in the height direction Z (the stacking direction of the current collection structure 4) and are arranged in the longitudinal direction X (the direction in which the parallel units 16 are arranged). Multiple second conductive plates 7 are arranged similarly.

[0055] Multiple first conductive plates 5 each cover multiple parallel units 16. Multiple second conductive plates 7 each cover multiple first conductive plates 5 via an insulating layer 6, and further cover multiple parallel units 16 as well.

[0056] The first conductive plate 5 is connected to the first electrodes of a plurality (for example, nine) of battery cells 10 that constitute the corresponding parallel unit 16. The second conductive plate 7 is connected to the second electrodes of a plurality (for example, nine) of battery cells 10 that constitute the corresponding parallel unit 16, while being insulated from the first conductive plate 5. In this embodiment, the first electrode is the peripheral electrode 13 and the second electrode is the central electrode 14. The polarity of the first electrode and the second electrode is not particularly limited.

[0057] As a result, in each parallel unit 16, two or more (for example, nine) battery cells 10 are connected in parallel to each other between the corresponding first conductive plate 5 and second conductive plate 7.

[0058] Multiple connecting wires 8 connect each of the multiple second conductive plates 7 to the first conductive plate 5 adjacent to it on one side in the longitudinal direction X (left side of the paper in Figures 2 and 5). As a result, multiple parallel units 16 are connected sequentially in series.

[0059] In this embodiment, the connecting wire 8 is integrally provided on the second conductive plate 7. On the other hand, the first conductive plate 5 is provided with a tab 9 that is connected to the connecting wire 8.

[0060] The second conductive plate 7 located at one end in the longitudinal direction X does not have a first conductive plate 5 to which it should be connected via a connecting wire 8. Similarly, the first conductive plate 5 located at the other end in the longitudinal direction X does not have a second conductive plate 7 to which it should be connected via a connecting wire 8. Therefore, the number of connecting wires 8 and tabs 9 is one less than the number of parallel units 16, first conductive plates 5, and second conductive plates 7 (for example, 11).

[0061] Furthermore, in order to standardize the components of the second conductive plate 7, the second conductive plate 7 located at one end in the longitudinal direction X may also be provided with the same structure as the connecting wire 8. In order to standardize the components of the first conductive plate 5, the first conductive plate 5 located at the other end in the longitudinal direction X may also be provided with the same structure as the tab 9. When the peripheral electrode 13 is the negative electrode and the central electrode 14 is the positive electrode, the same structure as the connecting wire 8 may be used as terminal 3a of the battery assembly 3 at one end and connected to the wire. The same structure as the tab 9 may be used as terminal 3b of the battery assembly 3 at the other end and connected to the ground wire. Depending on the polarity of the peripheral electrode 13 and the central electrode 14, the polarity of terminals 3a and 3b may change.

[0062] Referring to Figures 6, 7B, 8, and 9, the first conductive plate 5 has a flat first base portion 5a, a plurality of exposed openings 5b provided on the first base portion 5a, and a plurality of first lead wires 5c extending from the periphery of each of the exposed openings 5b. The first base portion 5a is singular. The number of exposed openings 5b and first lead wires 5c is the same as the number of battery cells 10 included in one parallel unit 16 (for example, 9). The exposed openings 5b may be through holes or notches.

[0063] Each first lead wire 5c extends from the first base 5a toward the battery assembly 3 in the height direction Z (the stacking direction of the current collection structure 4), and bends to extend approximately parallel to the first base 5a. The tip 5d of the first lead wire 5c is elongated and rectangular in shape.

[0064] When the first conductive plate 5 is placed on the cell holder 20, the periphery of the exposed opening 5b is supported by the outer surface 24, and the central electrode 14 is exposed through the central opening 23 and the exposed opening 5b. The first lead wire 5c passes through the through hole 26. The tip 5d of the first lead wire 5c is in contact with the peripheral electrode 13. A welding tool is inserted into the through hole 26, and the first lead wire 5c is welded to the peripheral electrode 13. As a result, the first conductive plate 5 is mechanically and electrically connected to the peripheral electrode 13.

[0065] The first conductive plate 5 has a first lead plate 31 and a first current collector plate 32. The first lead wire 5c is made up solely of the first lead plate 31. The first current collector plate 32 is superimposed on the first lead plate 31 from the side opposite to the first lead wire 5c. The first current collector plate 32 has a greater thickness than the first lead plate 31.

[0066] As can be seen from the comparison between Figure 7A and Figure 7B, the shape of the first current collector plate 32 is identical to that of the first lead plate 31, except for the presence or absence of the first lead wire 5c. Figure 7A is a drawing to clarify the positional relationship of the battery assembly 3, the first lead plate 31, and the first current collector plate 32 in a plan view. The assembly of the first conductive plate 5 to the battery assembly 3 is performed with the first lead plate 31 and the first current collector plate 32 already laminated and joined (see Figure 6).

[0067] Tab 9 is composed of both the first lead plate 31 and the first current collector plate 32. Multiple tabs 9 are provided on a single first conductive plate 5. For example, the number of tabs 9 is the same as the number of battery cells 10 constituting each cell row 15 (for example, 3). Multiple tabs 9 are arranged at intervals in the width direction Y. Each tab 9 is a flat plate-like and rectangular shape that protrudes to the other side in the longitudinal direction X. Each tab 9 is positioned between two adjacent battery cells 10.

[0068] Referring to Figures 3, 7C, 8, and 9, the insulating layer 6 is composed of a single plate made of an insulating material such as synthetic resin or rubber. The insulating layer 6 covers multiple first conductive plates 5 simultaneously. The insulating layer 6 has an electrode opening 6a that exposes the central electrode 14 and a tab opening 6b that exposes the tab 9. In this embodiment, the tab opening 6b is continuous with the electrode opening 6a.

[0069] When the insulating layer 6 is placed on the first conductive plate 5, the periphery of the electrode opening 6a partially blocks the exposed opening 5b, and the first lead wire 5c is covered by the insulating layer 6. On the other hand, the central electrode 14 is exposed through the central opening 23, the exposed opening 5b, and the electrode opening 6a. Also, some of the tabs 9 are exposed through the tab opening 6b. The remaining tabs 9 are located outside the insulating layer 6 and are therefore exposed.

[0070] Referring to Figures 6, 7E, 8, and 9, the second conductive plate 7 has a flat second base portion 7a, a plurality of work openings 7b provided on the second base portion 7a, and a plurality of second lead wires 7c extending from the second base portion 7a. The second base portion 7a is singular. The number of second lead wires 7c is the same as the number of battery cells 10 included in one parallel unit 16 (for example, 9).

[0071] Each second lead wire 7c extends from the second base 7a toward the battery assembly 3 in the height direction Z (the stacking direction of the current collection structure 4), and bends to extend approximately parallel to the second base 7a. The tip 7d of the second lead wire 7c is rectangular in shape and wider than that of the first lead wire 5c. The three second lead wires 7c on one side in the longitudinal direction X and the three second lead wires 7c in the center of the longitudinal direction X extend from the periphery of the work opening 7b into the inside of the work opening 7b. The second conductive plate 7 is shorter in the longitudinal direction X than the first conductive plate 5, and a gap is formed between two adjacent second conductive plates 7 in the longitudinal direction X. The three second lead wires 7c on the other side in the longitudinal direction X extend from the periphery of the second base 7a into this gap.

[0072] When the second conductive plate 7 is placed on the insulating layer 6, the second base portion 7a is supported by the insulating layer 6. The second lead wire 7c passes through the electrode opening 6a, the exposed opening 5b, and the central opening 23. The tip portion 7d of the second lead wire 7c is in contact with the central electrode 14. For the six second lead wires 7c on one side and in the center of the longitudinal direction X, a welding tool is inserted into the central opening 23 through the work opening 7b, the electrode opening 6a, and the exposed opening 5b, and the second lead wires 7c are welded to the central electrode 14. For the three second lead wires 7c on the other side of the longitudinal direction X, a welding tool is inserted into the central opening 23 through the gap, the electrode opening 6a, and the exposed opening 5b, and the second lead wires 7c are welded to the central electrode 14. As a result, the second conductive plate 7 is mechanically and electrically connected to the central electrode 14.

[0073] The second conductive plate 7 has a second lead plate 41 and a second current collector plate 42. The second lead wire 7c is made up solely of the second lead plate 41. The second current collector plate 42 is superimposed on the second lead plate 41 from the side opposite to the second lead wire 7c. The second current collector plate 42 has a greater thickness than the second lead plate 41.

[0074] As can be seen from the comparison between Figure 7D and Figure 7E, the shape of the second current collector plate 42 is identical to that of the second lead plate 41, except for the presence or absence of the second lead wire 7c and connecting wire 8. Figure 7D is a drawing to clarify the positional relationship of the battery assembly 3, insulating layer 6, second lead plate 41, and second current collector plate 42 in a plan view. The assembly of the second conductive plate 7 to the battery assembly 3 is performed with the second lead plate 41 and the second current collector plate 42 already laminated and joined together.

[0075] The connecting wires 8, like the second lead wires 7c, are composed solely of the second lead plate 41. Multiple connecting wires 8 are provided on a single second lead plate 41. The number of connecting wires 8 is the same as the number of tabs 9 (for example, 3). The multiple connecting wires 8 are spaced apart in the width direction Y. Each connecting wire 8, like the second lead wires 7c, extends from one edge in the longitudinal direction X of the second lead plate 41 toward the battery assembly 3 in the height direction Z, and is inclined toward one side in the longitudinal direction X. Each connecting wire 8 is bent and extends parallel to the second base portion 7a. The tip portion 8a of the connecting wire 8 is rectangular in shape.

[0076] When the second conductive plate 7 is placed on the insulating layer 6, the tip 8a of the connecting wire 8 contacts the corresponding tab 9. Some of the connecting wire 8 passes through the tab opening 6b and contacts the tab 9. The remaining connecting wire 8 passes outside the insulating layer 6 and contacts the tab 9. In this embodiment, the connecting wire 8 is welded to the tab 9 at the same time as the welding of the three second lead wires 7c on the other side in the longitudinal direction X to the central electrode 14. As a result, the second conductive plate 7 is mechanically and electrically connected to the adjacent first conductive plate 5 via the connecting wire 8 and the tab 9.

[0077] Multiple battery cells 10 are arranged in a staggered pattern. Specifically, in each cell row 15, multiple battery cells 10 are arranged at equal intervals in the width direction Y (the direction in which the cell row 15 extends). Each battery cell 10 is offset in the width direction Y from the battery cells 10 that make up the cell row 15 on either side.

[0078] Multiple cell rows 15 can be divided into odd-numbered rows (hereinafter referred to as "odd cell row 15A") and even-numbered rows (hereinafter referred to as "even cell row 15B"), counting from one end in the longitudinal direction X. The odd cell row 15A and even cell row 15B are arranged alternately in the longitudinal direction X. The battery cells 10 of the odd cell row 15A are positioned closer to one side in the width direction Y (lower left side of Figure 2) relative to the battery cells 10 of the even cell row 15B.

[0079] Multiple parallel units 16 can also be divided into odd-numbered units (hereinafter referred to as "odd units 16A") and even-numbered units (hereinafter referred to as "even units 16B"), counting from one end in the longitudinal direction X. The odd units 16A and even units 16B are arranged alternately in the longitudinal direction X. An odd unit 16A consists of two columns of odd-numbered cells 15A and one column of even-numbered cells 15B. An even unit 16B consists of one column of odd-numbered cells 15A and two columns of even-numbered cells 15B.

[0080] The multiple first conductive plates 5 can also be divided into odd-numbered plates (hereinafter referred to as "odd-numbered first conductive plates 5A") and even-numbered plates (hereinafter referred to as "even-numbered first conductive plates 5B"), counting from one end in the longitudinal direction X. The multiple second conductive plates 7 can also be divided into odd-numbered plates (hereinafter referred to as "odd-numbered second conductive plates 7A") and even-numbered plates (hereinafter referred to as "even-numbered second conductive plates 7B"), counting from one end in the longitudinal direction X.

[0081] The odd-numbered first conductive plate 5A and the even-numbered first conductive plate 5B have the same configuration as the first conductive plate 5 as described above. Due to the difference in the arrangement of the battery cells 10 between the odd-numbered unit 16A and the even-numbered unit 16B, the shape of the odd-numbered first conductive plate 5A and the shape of the even-numbered first conductive plate 5B are different from each other. The same applies to the odd-numbered second conductive plate 7A and the even-numbered second conductive plate 7B.

[0082] For example, an odd-numbered first conductive plate 5A corresponds to an odd-numbered unit 16A. In each odd-numbered unit 16A, an odd-numbered cell row 15A is arranged on the other side in the longitudinal direction X, and the battery cells 10 are positioned towards one side in the width direction Y. Conversely, the three tabs 9 of the odd-numbered first conductive plate 5A are positioned towards the other side in the width direction Y. On the other side in the longitudinal direction X of the odd-numbered unit 16A, the battery cells 10 and tabs 9 are arranged alternately from one side in the width direction Y.

[0083] The tabs 9 of the odd-numbered first conductive plates 5A are connected to the connecting wires 8 of the even-numbered second conductive plates 7B. In each even-numbered unit 16B, the even-numbered cell rows 15B are arranged on one side in the longitudinal direction X, and the battery cells 10 are positioned on the other side in the width direction Y. The three connecting wires 8 of the even-numbered second conductive plates 7B are provided adjacent to the second lead wires 7c corresponding to the even-numbered cell rows 15B on one side in the longitudinal direction X, and extend to the opposite side in the longitudinal direction from the second lead wires 7c. As a result, the connecting wires 8 of the even-numbered second conductive plates 7B overlap with the tabs 9 of the odd-numbered first conductive plates 5A. At the other end in the width direction Y, the tabs 9 and connecting wires 8 are positioned on the other side in the width direction Y relative to the odd-numbered cell rows 15A and are exposed outside the insulating layer 6. The insulating layer 6 and, consequently, the current collection structure 4 are miniaturized in the width direction.

[0084] In contrast, the even-numbered first conductive plate 5B corresponds to the even-numbered unit 16B. In each even-numbered unit 16B, an even-numbered cell row 15B is arranged on the other side in the longitudinal direction X, and the battery cells 10 are positioned towards the other side in the width direction Y. The three tabs 9 of the even-numbered first conductive plate 5B are positioned towards one side in the width direction Y. On the other side in the longitudinal direction X of the even-numbered unit 16B, the tabs 9 and battery cells 10 are arranged alternately from one side in the width direction Y.

[0085] The tabs 9 of the even-numbered first conductive plates 5B are connected to the connecting wires 8 of the odd-numbered second conductive plates 7A. In each odd-numbered unit 16A, odd-numbered cell rows 15A are arranged on one side in the longitudinal direction X, and the battery cells 10 are positioned on one side in the width direction Y. The three connecting wires 8 of the odd-numbered second conductive plates 7A are provided adjacent to the second lead wires 7c corresponding to the odd-numbered cell rows 15A on one side in the longitudinal direction X, and extend to the opposite side in the longitudinal direction from the second lead wires 7c. As a result, the connecting wires 8 of the odd-numbered second conductive plates 7A overlap with the tabs 9 of the even-numbered first conductive plates 5B. At the other end in the width direction Y, the tabs 9 and connecting wires 8 are positioned on one side in the width direction Y relative to the even-numbered cell rows 15B and are exposed outside the insulating layer 6. The insulating layer 6 and, consequently, the current collection structure 4 are miniaturized in the width direction.

[0086] (Second Embodiment) Referring to Figures 10 and 11, the battery module 1 according to the second embodiment will be described, focusing on the differences from the first embodiment. Although Figures 10 and 11 show only three parallel units 16, the battery module 1 may have more parallel units 16.

[0087] The battery module 1 according to this embodiment includes a first positioning structure 51, a second positioning structure 52, and a third positioning structure 53.

[0088] The first positioning structure 51 positions the first conductive plate 5 relative to the cell holder 20. The first positioning structure 51 consists of a first positioning projection 51a provided on the outer surface 24 of the cell holder 20 and a first positioning hole 51b provided in the first conductive plate 5. Each first conductive plate 5 is provided with two first positioning holes 51b.

[0089] Each first conductive plate 5 is placed on the cell holder 20 such that two first positioning protrusions 51a are inserted through two first positioning holes 51b, respectively. This improves the accuracy of the position of the first conductive plate 5 relative to the cell holder 20 in the longitudinal direction X, the width direction Y, and the orientation around the height direction Z axis.

[0090] The second positioning structure 52 positions the second conductive plate 7 relative to the insulating layer 6. The second positioning structure 52 consists of a second positioning projection 52a provided on the surface of the insulating layer 6 and a second positioning hole 52b provided in the second conductive plate 7. Each second conductive plate 7 is provided with two second positioning holes 52b.

[0091] Each second conductive plate 7 is superimposed on the insulating layer 6 such that two second positioning protrusions 52a are inserted through two second positioning holes 52b, respectively. This improves the accuracy of the position of the second conductive plate 7 relative to the insulating layer 6 in the longitudinal direction X, the width direction Y, and the orientation around the height direction Z axis.

[0092] The third positioning structure 53 positions the insulating layer 6 relative to the cell holder 20. The third positioning structure 53 consists of a third positioning projection 53a provided on the outer surface 24 of the cell holder 20 and a third positioning hole 53b provided in the insulating layer 6.

[0093] The third positioning projection 53a is positioned in an area that is not covered by the first conductive plate 5 but is covered by the insulating layer 6. Specifically, in the longitudinal direction X, the third positioning projection 53a is positioned in the area between two odd-numbered cell rows 15A that constitute an odd-numbered unit 16A, and in the width direction Y, it is positioned in an area on one side of the battery cell 10 that forms an even-numbered cell row 15B between the two odd-numbered cell rows 15A.

[0094] The insulating layer 6 is superimposed on the cell holder 20 such that multiple third positioning protrusions 53a are inserted through multiple third positioning holes 53b. This improves the accuracy of the position of the insulating layer 6 relative to the cell holder 20 in the longitudinal direction X, the width direction Y, and the orientation around the height direction Z axis.

[0095] The battery module 1 according to this embodiment further includes a fastening structure 60 that removably fastens the connecting wires 8 and tabs 9 to the cell holder 20. In this embodiment, in order to secure space for the fastening structure 60, the tab opening 6b is separated from the electrode opening 6a in the longitudinal direction X.

[0096] The fastening structure 60 includes a female screw hole 61 provided on the outer surface 24 of the cell holder 20, a tab through hole 62 provided in the tab 9, a connecting wire through hole 63 provided in the tip 8a of the connecting wire 8, and a bolt 64 that is screwed into the female screw hole 61. The female screw hole 61 may be formed directly on the cell holder 20 by tapping. As shown in the illustrated example, the cell holder 20 may have a recess that opens to the outer surface 24, and a nut 61a having the female screw hole 61 may be fitted into the recess. In this case, if the recess and the nut 61a are non-circular, typically hexagonal in shape, the rotation of the nut 61a during fastening can be prevented.

[0097] When the first conductive plate 5 is placed on the cell holder 20, the tab through-hole 62 aligns with the female screw hole 61. Since the tab 9 is not covered by the insulating layer 6, the tab through-hole 62 and female screw hole 61 remain exposed even when the insulating layer 6 is placed on the first conductive plate 5. When the second conductive plate 7 is placed on the insulating layer 6, the connection wire through-hole 63 aligns with the tab through-hole 62 and female screw hole 61. In this state, the bolt 64 is inserted sequentially through the connection wire through-hole 63 and the tab through-hole 62, and then inserted into the female screw hole 61. By tightening the bolt 64, the connection wire 8 and the tab 9 are fastened together to the cell holder 20. The conductive plates can be assembled and disassembled in units of 16 parallel units, improving the handling of the conductive plates.

[0098] While embodiments have been described above, various modifications are possible to the above configuration within the scope of the spirit of this disclosure.

[0099] The connecting wire 8 does not have to be integrally formed with the second conductive plate 7. It may be integrally formed with the first conductive plate 5, or it may be separate from the first conductive plate 5 and the second conductive plate 7. However, as in the above embodiment, integrally forming it with the second conductive plate 7 improves ease of assembly.

[0100] Either the positioning structure or the fastening structure 60 may be applied. When the positioning structure is applied, at least one of the first positioning structure 51, the second positioning structure 52, and the third positioning structure 53 may be applied. In each positioning structure, the arrangement of the protrusions and holes may be reversed.

[0101] This disclosure may include the following embodiments: (Embodiment 1) A battery module comprising: a plurality of battery cells constituting a plurality of parallel units, each of which consists of two or more battery cells connected in parallel to each other, each of which has a first electrode and a second electrode with opposite polarity; a plurality of first conductive plates covering each of the plurality of parallel units, each of which is connected to the first electrode of the two or more battery cells constituting the corresponding parallel unit; a plurality of second conductive plates covering each of the plurality of first conductive plates, each of which is connected to the second electrode of the two or more battery cells constituting the corresponding parallel unit; and a plurality of connecting lines connecting each of the plurality of second conductive plates to the adjacent first conductive plate in order to sequentially connect the plurality of parallel units in series. (Embodiment 2) The battery module according to Embodiment 1, wherein the connecting lines are integrally provided on the second conductive plate, and the first conductive plate has tabs connected to the connecting lines. (Aspect 3) The battery module according to aspect 2, wherein the tab is positioned between two adjacent battery cells. (Aspect 4) The battery module according to aspect 2 or 3, further comprising: a cell holder that holds the plurality of battery cells and on which the first conductive plate is stacked; and a fastening structure that removably fastens the connecting wire and the tab to the cell holder in a state in which the cell holder, the tab, and the connecting wire are stacked in order. (Aspect 5) The battery module according to any one of aspects 1 to 4, further comprising: a cell holder that holds the plurality of battery cells and on which the first conductive plate is stacked; an insulating layer interposed between the first conductive plate and the second conductive plate; and at least one of a first positioning structure for positioning the first conductive plate and the insulating layer relative to the cell holder; a second positioning structure for positioning the second conductive plate relative to the insulating layer; and a third positioning structure for positioning the insulating layer relative to the cell holder.(Aspect 6) The battery module according to any one of aspects 1 to 5, wherein the first conductive plate comprises a first lead plate having a first lead wire connected to the first electrode and a first current collector plate superimposed on the first lead plate, and the first current collector plate has a greater thickness than the first lead plate. (Aspect 7) The battery module according to any one of aspects 1 to 6, wherein the second conductive plate comprises a second lead plate having a second lead wire connected to the second electrode and a second current collector plate superimposed on the second lead plate, and the second current collector plate has a greater thickness than the second lead plate. (Aspect 8) The battery module according to aspect 7, wherein the first conductive plate has a tab connected to the connecting wire, and the connecting wire is integrally provided on the second lead plate. (Aspect 9) The battery module according to any one of aspects 1 to 8, further comprising an insulating layer interposed between the first conductive plate and the second conductive plate. (Aspect 10) The battery module according to aspect 9, wherein the first conductive plate has a first lead wire connected to the first electrode, the second conductive plate has a second lead wire connected to the second electrode, the insulating layer has an electrode opening that exposes the second electrode and allows the second lead wire to pass through, and the first lead wire is covered by the peripheral edge of the electrode opening of the insulating layer. (Aspect 11) The battery module according to aspect 9 or 10, wherein the connecting wire is integrally provided on the second conductive plate, the first conductive plate has a tab connected to the connecting wire, and the insulating layer has a tab opening that exposes the tab and allows the connecting wire to pass through. (Aspect 12) The battery module according to any one of aspects 1 to 11, wherein the first electrode is provided on the peripheral edge of the battery cell and the second electrode is provided on the central part of the battery cell. (Aspect 13) The battery module according to aspect 12, wherein each of the battery cells is cylindrical, the first electrode and the second electrode are provided at the same end of the battery cell, and the plurality of battery cells are arranged parallel to each other such that the ends on which the first electrode and the second electrode are provided face the first conductive plate.

[0102] 1. Battery module 2. Outer casing 3. Battery assembly 3a, 3b Terminals 4. Current collection structure 5. First conductive plate 5a. First base 5b. Exposed opening 5c. First lead wire 5d. Tip 5A. Odd-numbered first conductive plate 5B. Even-numbered first conductive plate 6. Insulating layer 6a. Electrode opening 6b. Tab opening 7. Second conductive plate 7a. Second base 7b. Work opening 7c. Second lead wire 7d. Tip 7A. Odd-numbered second conductive plate 7B. Even-numbered second conductive plate 8. Connecting wire 8a. Tip 9. Tab 10. Battery cell 11. Outer casing 12. Sealing plate 13. Peripheral electrode 14. Central electrode 15. Cell row 15A. Odd-numbered cell row 15B. Even-numbered cell row 16. Parallel unit 16A. Odd-numbered unit 16B. Even-numbered unit 20 Cell holder 21 Housing section 22 Insertion opening 23 Central opening 24 Outer surface 25 Inner bottom surface 26 Through hole 31 First lead plate 32 First current collector plate 41 Second lead plate 42 Second current collector plate 51 First positioning structure 51a First positioning projection 51b First positioning hole 52 Second positioning structure 52a Second positioning projection 52b Second positioning hole 53 Third positioning structure 53a Third positioning projection 53b Third positioning hole 60 Fastening structure 61 Female screw hole 61a Nut 62 Tab through hole 63 Connecting wire through hole 64 Bolt

Claims

1. A battery module comprising: a plurality of battery cells constituting a plurality of parallel units, each of which consists of two or more battery cells connected in parallel to each other, and each of which has a first electrode and a second electrode with opposite polarities; a plurality of first conductive plates covering each of the plurality of parallel units, each of which is connected to the first electrode of the two or more battery cells constituting the corresponding parallel unit; a plurality of second conductive plates covering each of the plurality of first conductive plates, each of which is connected to the second electrode of the two or more battery cells constituting the corresponding parallel unit; and a plurality of connecting lines connecting each of the plurality of second conductive plates to the adjacent first conductive plate in order to sequentially connect the plurality of parallel units in series.

2. The battery module according to claim 1, wherein the connecting wire is integrally provided on the second conductive plate, and the first conductive plate has a tab connected to the connecting wire.

3. The battery module according to claim 2, wherein the tab is positioned between two adjacent battery cells.

4. The battery module according to claim 2, further comprising: a cell holder that holds the plurality of battery cells and on which the first conductive plate is stacked; and a fastening structure that removably fastens the connecting wire and the tab to the cell holder while the cell holder, the tab, and the connecting wire are stacked in order.

5. A battery module according to any one of claims 1 to 4, further comprising: a cell holder for holding the plurality of battery cells and on which the first conductive plate is stacked; an insulating layer interposed between the first conductive plate and the second conductive plate; and at least one of a first positioning structure for positioning the first conductive plate and the insulating layer with respect to the cell holder; a second positioning structure for positioning the second conductive plate with respect to the insulating layer; and a third positioning structure for positioning the insulating layer with respect to the cell holder.

6. The battery module according to any one of claims 1 to 4, wherein the first conductive plate comprises a first lead plate having first lead wires connected to the first electrode, and a first current collector plate superimposed on the first lead plate, the first current collector plate having a greater thickness than the first lead plate.

7. The battery module according to any one of claims 1 to 4, wherein the second conductive plate comprises a second lead plate having a second lead wire connected to the second electrode, and a second current collector plate superimposed on the second lead plate, the second current collector plate having a greater thickness than the second lead plate.

8. The battery module according to claim 7, wherein the first conductive plate has a tab connected to the connecting wire, and the connecting wire is integrally provided with the second lead plate.

9. The battery module according to any one of claims 1 to 4, further comprising an insulating layer interposed between the first conductive plate and the second conductive plate.

10. The battery module according to claim 9, wherein the first conductive plate has a first lead wire connected to the first electrode, the second conductive plate has a second lead wire connected to the second electrode, the insulating layer has an electrode opening that exposes the second electrode and allows the second lead wire to pass through, and the first lead wire is covered by the peripheral edge of the electrode opening of the insulating layer.

11. The battery module according to claim 9, wherein the connecting wire is integrally provided on the second conductive plate, the first conductive plate has a tab connected to the connecting wire, and the insulating layer has a tab opening that exposes the tab and allows the connecting wire to pass through.

12. The battery module according to any one of claims 1 to 4, wherein the first electrode is provided on the periphery of the battery cell and the second electrode is provided on the central part of the battery cell.

13. The battery module according to claim 12, wherein each of the battery cells is cylindrical, the first electrode and the second electrode are provided at the same end of the battery cell, and the plurality of battery cells are arranged parallel to each other such that the ends on which the first electrode and the second electrode are provided face the first conductive plate.

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