Battery pack

Abstract

A battery pack comprises: a battery group in which batteries 100 and cell spacers 202 are alternately stacked; end members arranged on the side surfaces of the battery group that are positioned at both stacking-direction ends of the batteries 100; and second side plates 232 arranged on the side surfaces of the battery group that extend along the stacking direction, the second side plates 232 engaging with the cell spacers 202. The second side plates 232 each include a first protrusion 232a positioned on the side of the battery pack distant from a mounting surface S, and a second protrusion 232b positioned on the side of the battery pack near the mounting surface S, as a set of protrusions that bend from the side surfaces extending along the stacking direction in the direction of the batteries 100 and engage with the cell spacers 202. The cell spacers 202 each have a first engagement part 202a that engages with the first protrusion 232a, and a second engagement part 202b that engages with the second protrusion 232b. The ratio of a first interval (D1) that is the interval between the first protrusion 232a and the first engagement part 202a to a second interval (D2) that is the interval between the second protrusion 232b and the second engagement part 202b is within the range of 0.5-2.0. There is thereby provided a battery pack in which, even when vibration is applied to the battery pack, the side plates are unlikely to come off, and deformation is unlikely to occur.

Description

battery pack

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

[0002] 2. Description of the Related Art Conventionally, there has been known a battery pack in which a battery group, in which unit cells and spacers are alternately stacked, is fastened together with end plates and side plates.

[0003] Patent Document 1 describes an energy storage device including an energy storage element and a spacer. In this energy storage device, the spacer has a main body and a third protrusion that protrudes in a first direction from the main body toward the side or bottom of the energy storage element and has a shape that does not abut against the surface of the energy storage element facing the first direction, and the edge of the main body in the first direction is located on the opposite side of the surface of the energy storage element facing the first direction. Patent Document 2 describes an energy storage device that includes an energy storage element having a container, a spacer having a spacer main body located on one side of the energy storage element in the first direction, and a side member having a side main body located on one side of the energy storage element in a second direction that intersects the first direction. Patent Document 3 describes a battery pack. This battery pack includes battery cells having a pair of first surface portions facing each other in a first direction, with positive and negative plates arranged side by side in the first direction and stacked in the first direction, an outer shell portion that houses the stacked battery cells, elastic members provided between adjacent battery cells in the first direction, and a plurality of frames for fixing each battery cell to the outer shell portion.

[0004] International Publication No. 2019 / 181502 International Publication No. 2020 / 196189 Japanese Patent Application Laid-Open No. 2021-136101

[0005] It is required that the side plates are not easily detached and the battery assembly is not easily deformed when vibration is applied to the battery assembly. An object of the present invention is to provide a battery assembly in which the side plates are not easily detached and are not easily deformed even when vibration is applied to the battery assembly.

[0006] In order to solve the above-mentioned problems, the battery pack of the present invention includes a battery group in which single cells and spacers are alternately stacked, end members arranged on side surfaces of the battery group that are located at both ends in the stacking direction of the single cells, and side plates arranged on side surfaces of the battery group that are along the stacking direction and engage with the spacers, wherein the side plates have a set of protrusions that bend from the side surface along the stacking direction toward the single cells and engage with the spacers, including a first protrusion located on the side farther from the mounting surface of the battery pack and a second protrusion located on the side closer to the mounting surface of the battery pack, and the spacers have a first engagement portion that engages with the first protrusion and a second engagement portion that engages with the second protrusion, and the ratio of a first distance (D1) that is the distance between the first protrusion and the first engagement portion to a second distance (D2) that is the distance between the second protrusion and the second engagement portion is in the range of 0.5 to 2.0.

[0007] In addition, in order to solve the above-mentioned problems, the battery pack of the present invention comprises a battery group in which single cells and spacers are alternately stacked, end members arranged on side surfaces of the battery group that are located at both ends in the stacking direction of the single cells, and side plates arranged on side surfaces of the battery group that are along the stacking direction and engage with the spacers, wherein the side plates have a set of protrusions that bend from the side surface along the stacking direction toward the battery group and engage with the spacers, including a first protrusion located on the side farther from the mounting surface of the battery pack and a second protrusion located on the side closer to the mounting surface of the battery pack, and the spacers have a first engagement portion that engages with the first protrusion and a second engagement portion that engages with the second protrusion, and form a space portion to separate the side plates and the single cells by a predetermined distance.

[0008] According to the present invention, it is possible to provide a battery pack in which the side plates are not easily detached or deformed even when vibration is applied to the battery pack.

[0009] 6 is a perspective view showing a battery pack 1 according to an embodiment.

[0026] FIG. 6 is a perspective view showing a plurality of batteries 100 and a holding unit 200, with some of the components of the holding unit 200 disassembled in the width direction Y and the stacking direction X.

[0027] FIG. 7 is a perspective view showing the components of the batteries 100 and the holding unit 200 disassembled in the stacking direction X, with the first side plate 231, the second side plate 232, and the fastening bolts 241 removed from FIG. 2 .

[0028] FIG. 7 is a perspective view showing the configuration of a bus bar unit 300 and a voltage detection unit 400.

[0029] FIG. 7 is a diagram showing the configuration of a bus bar 302 and its surroundings.

[0030] FIG. 7 is a diagram showing the first side plate 231, the second side plate 232, and the cell spacer 202 as viewed from the X direction in FIG. 2 .

[0031] FIG. 7(a) is an enlarged view of portion VII in FIG. 6 .

[0032] FIG. 7(b) is an enlarged view of portion VIII in FIG. 7(a) .

[0032] FIG. 7(b) is an enlarged view of portion IX in FIG. 7(a) .

[0033] FIG. 7(b) is an enlarged view of portion IX in FIG. 7(a) .

[0034] FIG. 7(b) is a diagram showing the second side plate 232 detached from the cell spacer 202.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0011] <Overall Description of Battery Assembly 1> The configuration of the battery assembly 1 according to the embodiment will be described with reference to FIGS. 1 to 5. Embodiments of the present invention will be described with reference to the drawings. To facilitate understanding of each embodiment, the size and proportions of components may be exaggerated in each drawing. The same reference numerals are used for the same components in each drawing. In each drawing, the stacking direction X, width direction Y, and height direction Z of the battery assembly 1 are indicated by arrows. However, in each drawing, the stacking direction X, width direction Y, and height direction Z of the battery assembly 1 indicate the relative positional relationship within the same drawing. That is, if the battery assembly 1 is rotated 180 degrees and the top and bottom surfaces are reversed, or if the battery assembly 1 is rotated 90 degrees and the top surface is placed as a side, the stacking direction X, width direction Y, and height direction Z of the battery assembly 1 will change. In each drawing, the threads on the outer surfaces of the fastening bolts and the grooves on the inner surfaces of the insert nuts are omitted. Furthermore, the configuration of the battery pack 1 shown in FIGS. 1 to 5 is a schematic diagram that does not show details, and the shapes of the various parts may differ from those of the configuration shown in FIG. 6 and subsequent figures, for example.

[0012] Fig. 1 is a perspective view showing a battery pack 1 according to an embodiment. Fig. 2 is a perspective view showing a plurality of batteries 100 and a holding unit 200, with some of the components of the holding unit 200 disassembled in the width direction Y and the stacking direction X. Fig. 3 is a perspective view showing the components of the batteries 100 and the holding unit 200 disassembled in the stacking direction X, with a first side plate 231, a second side plate 232, and a fastening bolt 241 removed from Fig. 2.

[0013] The battery pack 1 is configured as, for example, a power source for operating a motor for running a vehicle. The battery pack 1 may also be configured as, for example, a power source for operating electrical equipment mounted on the vehicle.

[0014] 1 and 2, the battery pack 1 includes a plurality of batteries 100, a holding unit 200 that holds the plurality of batteries 100, and a bus bar unit 300 that electrically connects the plurality of batteries 100. The battery pack 1 also includes a voltage detection unit 400 that detects the voltage of the batteries 100, and a temperature measurement unit (not shown) that measures the temperature of the batteries 100.

[0015] (Configuration of Battery 100) The battery 100 is an example of a single cell, and is stacked in the stacking direction X via a holding unit 200. As shown in FIG. 2, for example, 20 batteries 100 are stacked. The battery 100 is configured, for example, by a lithium ion secondary battery. The battery 100 includes a current collector and an electrolyte. As shown in FIG. 3, the battery 100 includes a container 101, a lid 102, a positive electrode terminal 103, a negative electrode terminal 104, and a safety valve 105. The components included in the battery 100 will be described below.

[0016] As shown in FIG. 3 , the battery 100 is formed in a rectangular parallelepiped shape. A positive electrode terminal 103 and a negative electrode terminal 104 are provided on an upper surface 100a of the battery 100 along the stacking direction X. The upper surface 100a corresponds to the upper surface of the battery 100 in FIG. 2 . The upper surface 100a is formed in a rectangular shape. The length of the upper surface 100a along the width direction Y of the battery 100 is longer than the length of the upper surface 100a along the stacking direction X of the battery 100. The upper surface 100a faces the busbar unit 300 shown in FIG. 1 . Two side surfaces 100b along the stacking direction X of the battery 100 face each other perpendicularly to the upper surface 100a. The side surfaces 100b are formed in a rectangular shape. The length of the side surfaces 100b along the height direction Z of the battery 100 is longer than the length of the side surfaces 100b along the stacking direction X of the battery 100. Two main surfaces 100 c of the battery 100 that face each other in the stacking direction X are in contact with the cell spacers 202 and the like of the holding unit 200 .

[0017] The current collector of the battery 100 corresponds to a charge / discharge element between which electric power is input and output. The current collector of the battery 100 is configured by winding or stacking a positive electrode and a negative electrode with a separator interposed therebetween. The container 101 contains the current collector and an electrolyte. The lid 102, together with the container 101, seals the current collector and the electrolyte. The lid 102 is joined to the container 101. The positive electrode terminal 103 and the negative electrode terminal 104 relay the input and output of electric power between the current collector and the electrical device. The positive electrode terminal 103 and the negative electrode terminal 104 are attached to the lid 102. The positive electrode terminal 103 of one battery 100 and the negative electrode terminal 104 of the other battery 100, which are adjacent along the stacking direction X, face each other in the stacking direction X, as shown in FIG. 3 . The safety valve 105 ruptures toward the outside of the battery 100 when the internal pressure of the battery 100 exceeds a predetermined value. The safety valve 105 is also called a split valve. The safety valve 105 is provided in the lid 102, for example.

[0018] (Configuration of holding unit 200) The holding unit 200 holds multiple batteries 100. As shown in Figures 2 and 3, the holding unit 200 includes a first end spacer 201, a cell spacer 202, and a second end spacer 203. The holding unit 200 also includes a first end block 211, a second end block 212, an insulating member 221, and an insert nut 222. As shown in Figure 2, the holding unit 200 also includes a first side plate 231, a second side plate 232, and a fastening bolt 241. The components included in the holding unit 200 will be described below.

[0019] As shown in FIG. 3 , the first end spacer 201 is provided between the first end block 211 and the battery 100. The first end spacer 201 contacts the first battery 100 located at one end of the 20 stacked batteries 100. This battery 100 corresponds to the battery 100 located at the left end in FIG. 2 . The first end spacer 201 insulates the first end block 211 from the battery 100. The first end spacer 201 covers each side surface of the first end block 211 and the battery 100 along the width direction Y. The first end spacer 201 covers a portion of the side surface 100b of the battery 100 along the stacking direction X. The thickness of the first end spacer 201 along the stacking direction X is sufficiently thinner than the thickness of the batteries 100 along the stacking direction X. The first end spacer 201 is formed of an insulating material.

[0020] The cell spacer 202 is an example of a spacer, and as shown in FIG. 3 , is provided between adjacent batteries 100. In this case, it can also be said that a battery group is formed by alternately stacking the batteries 100 and the cell spacers 202. The cell spacer 202 holds and insulates the adjacent batteries 100. The cell spacer 202 covers the main surfaces 100c of each adjacent battery 100 along the width direction Y and a portion of the side surfaces 100b of each adjacent battery 100 along the stacking direction X. The thickness of the cell spacer 202 along the stacking direction X is sufficiently thinner than the thickness of the batteries 100 along the stacking direction X. The cell spacer 202 is made of an insulating material.

[0021] As shown in FIG. 3 , the second end spacer 203 is provided between the battery 100 and the second end block 212. The second end spacer 203 contacts the twentieth battery 100 located at the other end of the 20 stacked batteries 100. This battery 100 corresponds to the battery 100 located at the right end in FIG. 2 . The second end spacer 203 insulates the battery 100 from the second end block 212. The second end spacer 203 covers each side surface of the first end block 211 and the battery 100 along the width direction Y. The second end spacer 203 covers a portion of the side surface 100b of the battery 100 along the stacking direction X. The thickness of the second end spacer 203 along the stacking direction X is sufficiently thinner than the thickness of the batteries 100 along the stacking direction X. The second end spacer 203 is formed of an insulating material.

[0022] As shown in FIG. 3 , the first end block 211 is stacked with the first battery 100 located at one end of the 20 stacked batteries 100 via a first end spacer 201. The first end block 211 extends along a width direction Y that intersects with the stacking direction X of the batteries 100. The first end block 211 is adjacent to the battery 100 located at the end along the stacking direction X and supports the battery 100. The first end block 211 is formed in a rectangular parallelepiped shape extending in the width direction Y. Fastening bolts 241 are screwed into a plurality of screw holes 211m formed on the side surface of the first end block 211 along the width direction Y shown in FIG. 2 . The first end block 211 is fixed to the first side plate 231 by the fastening bolts 241, as shown in FIG. 1 . Similarly, the first end block 211 is fixed to the second side plate 232 by the fastening bolts 241. 3, the first end block 211 has insertion holes 211n for inserting bolts or the like to fix the battery pack 1. The first end block 211 is made of, for example, metal or resin.

[0023] As shown in FIG. 3 , the second end block 212 is stacked with the twentieth battery 100 located at the other end of the 20 stacked batteries 100 via a second end spacer 203. The second end block 212 extends along the width direction Y of the batteries 100. The second end block 212 is adjacent to the battery 100 located at the end along the stacking direction X and supports the battery 100. The second end block 212 is formed in a rectangular parallelepiped shape extending in the width direction Y. Fastening bolts 241 are screwed into multiple screw holes formed on the side surface of the second end block 212 along the width direction Y shown in FIG. 2 . The second end block 212 is fixed to the first side plate 231 by the fastening bolts 241, as shown in FIG. 1 . Similarly, the second end block 212 is fixed to the second side plate 232 by the fastening bolts 241. 3, the second end block 212 is formed with insertion holes 212n for inserting bolts or the like for fixing the battery pack 1. The second end block 212 is made of, for example, metal or resin.

[0024] The first end block 211 and the second end block 212 are side surfaces of the battery group, and function as end members arranged on the side surfaces located at both ends in the stacking direction of the batteries 100 .

[0025] 3, the insulating member 221 is inserted into the first end block 211. The insulating member 221 is also inserted into the second end block 212. The insulating member 221 is formed, for example, in a rectangular parallelepiped shape. The insulating member 221 is made of an insulating material.

[0026] The insulating member 221 may be configured as follows. That is, the insulating member 221 may be molded integrally with the first end spacer 201, or may be molded separately from the first end spacer 201 and then joined to the first end spacer 201. In such a case, the first end block 211 has a recess on its surface facing the first end spacer 201 that accommodates the insulating member 221 along the stacking direction X. Similarly, the insulating member 221 may be molded integrally with the second end spacer 203, or may be molded separately from the second end spacer 203 and then joined to the second end spacer 203. In such a case, the second end block 212 has a recess on its surface facing the second end spacer 203 that accommodates the insulating member 221 along the stacking direction X.

[0027] 3, the insert nut 222 is embedded in a recess formed in the upper surface of the insulating member 221. A fastening bolt is anchored to the insert nut 222 via a bus bar that is electrically connected to an external control device, for example.

[0028] As shown in FIGS. 1 and 2 , the first side plate 231 is arranged at one end of the stacked batteries 100 in the width direction Y, along the stacking direction X of the stacked batteries 100. The first side plate 231 holds the batteries 100 along the stacking direction X. Both ends of the first side plate 231 extending along the stacking direction X are bent toward the width direction Y. As shown in FIG. 2 , fastening bolts 241 are inserted into multiple insertion holes 231m formed on the side surface of the first side plate 231 along the width direction Y. As shown in FIGS. 1 and 2 , the first side plate 231 is fixed to the first end block 211 and the second end block 212 by the fastening bolts 241. The first side plate 231 is formed of, for example, metal.

[0029] As shown in FIGS. 1 and 2 , the second side plate 232 is arranged at the other end of the stacked batteries 100 in the width direction Y, along the stacking direction X of the stacked batteries 100. The second side plate 232 holds the batteries 100 along the stacking direction X. Both ends of the second side plate 232 extending along the stacking direction X are bent toward the width direction Y. As shown in FIG. 2 , fastening bolts 241 are inserted into multiple insertion holes 232m formed on the side surface of the second side plate 232 along the width direction Y. As shown in FIGS. 1 and 2 , the second side plate 232 is fixed to the first end block 211 and the second end block 212 by the fastening bolts 241. The second side plate 232 is formed of, for example, metal.

[0030] The first side plate 231 and the second side plate 232 are side surfaces of the battery group, are arranged on the side surfaces along the stacking direction of the batteries 100, and function as side plates that engage with the spacers.

[0031] 2, the fastening bolts 241 fasten the first side plate 231 to the first end block 211, and the first side plate 231 to the second end block 212. Also, the fastening bolts 241 fasten the second side plate 232 to the first end block 211, and the second side plate 232 to the second end block 212, as shown in FIG.

[0032] (Configuration of Busbar Unit 300 and Voltage Detection Unit 400) Fig. 4 is a diagram showing the configuration of busbar unit 300 and voltage detection unit 400. Fig. 5 is a diagram showing the configuration of busbar 302 and its surroundings.

[0033] As shown in Fig. 4, the bus bar unit 300 includes a first end bus bar 301, a plurality of bus bars 302, a second end bus bar 303, and a bus bar holder 311. As shown in Fig. 4, the voltage detection unit 400 includes a harness 450. As shown in Figs. 4 and 5, the harness 450 is an assembly that brings together a voltage detection line terminal 401, a voltage detection line 402, a connector 403, and a temperature measurement unit.

[0034] The first end bus bar 301 is joined to the positive electrode terminal 103 of the battery 100 that is closest to the first end block 211 among the 20 stacked batteries 100 .

[0035] The bus bar 302 electrically connects the terminals of the plurality of batteries 100. As a result, the bus bar 302 electrically connects one battery 100 and another battery 100 that are adjacent to each other along the stacking direction X, as shown in Fig. 2. The bus bar 302 joins the positive electrode terminal 103 of one battery 100 that are adjacent to each other along the stacking direction X with the negative electrode terminal 104 of the other battery 100 that are adjacent to each other along the stacking direction X.

[0036] The second end bus bar 303 is joined to the negative electrode terminal 104 of the battery 100 that is closest to the second end block 212 among the 20 stacked batteries 100 .

[0037] The busbar holder 311 mounts the busbar 302 and the voltage detection line terminal 401. The busbar holder 311 is provided with mounting areas for the busbar 302 and the voltage detection line terminal 401. The busbar 302 and the voltage detection line terminal 401 are then fitted in an overlapping manner into these mounting areas. The busbar holder 311 is, for example, a resin molded product.

[0038] The voltage detection line terminal 401 is disposed on top of the bus bar 302 and is joined to the bus bar 302. In this way, the voltage detection line terminal 401 detects the voltage of the battery 100. The voltage detection line 402 is joined to the voltage detection line terminal 401, and information on the voltage detected by the voltage detection line terminal 401 is sent to an external control device via a connector 403. The first end bus bar 301, the bus bar 302, the second end bus bar 303, and the voltage detection line terminal 401 are formed from, for example, a clad material in which copper and aluminum are joined together, copper, or aluminum.

[0039] <Detailed Description of First Side Plate 231, Second Side Plate 232, and Cell Spacer 202> Next, the first side plate 231, the second side plate 232, and the cell spacer 202 will be described in detail. FIG. 6 is a view of the first side plate 231, the second side plate 232, and the cell spacer 202 as viewed from the X direction in FIG. 2. FIG. 7(a) is an enlarged view of portion VIIa in FIG. 6. FIG. 7(b) is a perspective view of the cell spacer 202. Note that the second side plate 232 will be described below, but the same applies to the first side plate 231. As shown in FIG. 7(a), the second side plate 232 has a pair of protrusions that bend from a side surface along the stacking direction of the batteries 100 toward the batteries 100 and engage with the cell spacer 202. The first protrusion 232a is located on the side farther from the mounting surface S of the battery pack 1, and the second protrusion 232b is located on the side closer to the mounting surface S of the battery pack 1. In this case, the stacking direction X of the battery 100 is perpendicular to the paper surface. The first protrusion 232a and the second protrusion 232b bend leftward along the Y direction from the Z direction, which is the up-down direction in the figure. Furthermore, as shown in FIGS. 7(a) and 7(b), the cell spacer 202 has a first engaging portion 202a that engages with the first protrusion 232a and a second engaging portion 202b that engages with the second protrusion 232b. That is, the engagement of the first protrusion 232a with the first engaging portion 202a and the engagement of the second protrusion 232b with the second engaging portion 202b restricts the movement of the second side plate 232 relative to the cell spacer 202, for example, in the direction passing through the surface opposite the surface on which the battery terminals are located (the Z direction). In this case, the second side plate 232 is, for example, fitted into the cell spacer 202. In this case, the second side plate 232 and the cell spacer 202 have opposing surfaces in the Y direction, and the first engaging portion 202a and the second engaging portion 202b face the first protrusion 232a and the second protrusion 232b of the cell spacer 202, respectively, in the Z direction.

[0040] FIG. 8( a) is an enlarged view of portion VIIIa in FIG. 7( a). FIG. 8( b) is an enlarged view of portion VIIIb in FIG. 7( a). In this embodiment, the ratio of the first distance (D1) between the first protrusion 232a and the first engaging portion 202a to the second distance (D2) between the second protrusion 232b and the second engaging portion 202b is set to a range of 0.5 to 2.0. The first distance (D1) and the second distance (D2) are preferably smaller than the thicknesses of the first protrusion 232a and the second protrusion 232b. Alternatively, for example, the ratio is preferably 0.1 mm to 10 mm. This configuration makes it difficult for the first side plate 231 and the second side plate 232 to come off the cell spacer 202 even when vibration is applied to the battery pack 1.

[0041] 9 is a diagram showing a case where the second side plate 232 has come off the cell spacer 202. In this case, deformation of the battery pack 1 is likely to occur. In the above-described embodiment, by making it difficult for the first side plate 231 and the second side plate 232 to come off the cell spacer 202, deformation of the battery pack 1 is unlikely to occur, and a highly reliable battery pack 1 can be provided.

[0042] As shown in FIG. 7( b), the cell spacer 202 forms a space 235 for separating the second side plate 232 and the battery 100 by a predetermined distance D3. In other words, by providing the cell spacer 202 between the second side plate 232 and the battery 100, the space 235 is formed by the cell spacer 202. In this case, the distance D3 between the battery 100 and the main surface of the second side plate 232 facing the battery 100 is, for example, 1 mm or more and 50 mm or less in addition to the thickness of the cell spacer 202. Because the second side plate 232 is made of metal, it is necessary to ensure insulation between the second side plate 232 and the battery 100. By providing the cell spacer 202 and forming the space 235, insulation can be ensured at low cost. Furthermore, as described above, by making it difficult for the first side plate 231 and the second side plate 232 to come off the cell spacer 202 even when vibration is applied, insulation can be ensured even when vibration is applied.

[0043] The spacer 202 has thicker portions 202c and 202d formed on the side of the cell spacer 202 closer to the end (the end closer to the mounting surface and the end farther from the mounting surface) than the central portion 202e in the Z direction. The cell spacer 202 in the spacer 235 has thicker portions 202c and 202d at the end adjacent to the first engaging portion 202a and the end adjacent to the second engaging portion 202b, and has a central portion 202e between the thick portions 202c and 202d that is thinner than the thick portions 202c and 202d. For example, the thick portions 202c and 202d are thicker than the central portion 202e of the cell spacer 202 and protrude in the Y direction. This can also be said to mean that the cell spacer 202 in the space portion 235 has thick portions 202c and 202d at the end adjacent to the first engaging portion 202a and the end adjacent to the second engaging portion 202b, and that the thickness of the central portion 202e, where the thick portions 202c and 202d are not formed, is smaller than the thickness of the thick portions 202c and 202d. The thick portions 202c and 202d protrude, for example, from two to ten times the thickness of the cell spacer 202 in the central portion 202e. In this case, a thickness of two or more times is preferable to ensure sufficient spacing between the cell spacer 202 and the second side plate 232. On the other hand, a thickness of ten times or less is preferable to miniaturize the module. This reduces the contact area between the cell spacer 202 and the second side plate 232, which is preferable from the standpoint of insulation. Furthermore, a gap is formed between the cell spacer 202 and the second side plate 232 at the center portion 202e of the cell spacer 202 in the Z direction, which is preferable from the viewpoint of heat dissipation.

[0044] Furthermore, from the viewpoint of ensuring electrical insulation, the length (L1) of the first protrusion 232a shown in FIG. 8(a) is preferably in the range of 0.5 to 2.0 relative to the length (L2) of the second protrusion 232b shown in FIG. 8(b). Note that there may be cases where ensuring electrical insulation is the issue, but detachment of the first side plate 231 or the second side plate 232 from the cell spacer 202 is not an issue. In such cases, the length (L1) of the first protrusion 232a and the length (L2) of the second protrusion 232b must satisfy this range, but the ratio of the first distance (D1) to the second distance (D2) is not required to be in the above-mentioned range of 0.5 to 2.0. Furthermore, in this embodiment, the positive electrode terminal 103 and the negative electrode terminal 104 are disposed at the top of the battery 100. Therefore, to ensure electrical insulation, it is preferable to shorten the length (L1) of the first protrusion 232a. Therefore, the length (L2) of the second protrusion shown in Fig. 8(b) is preferably longer than the length (L1) of the first protrusion shown in Fig. 8(a). By doing so, better insulation performance can be obtained. Furthermore, from the viewpoint of insulation, it is preferable that the thickness of the thick portions 202c and 202d be greater than the protrusion lengths (L1 and L2) of the first protrusion 232a and the second protrusion 232b of the second side plate 232.

[0045] DESCRIPTION OF SYMBOLS 1... battery pack, 100... battery, 200... holding unit, 202... cell spacer, 202a... first engaging portion, 202b... second engaging portion, 202c, 202d... thickness portion, 202e... center portion, 211... first end block, 212... second end block, 231... first side plate, 232... second side plate, 232a... first protruding portion, 232b... second protruding portion, 300... busbar unit, 302... busbar, 311... busbar holder, 400... voltage detection unit

Claims

1. An assembled battery comprising: a battery group in which unit cells and spacers are alternately stacked; end members arranged on side surfaces of the battery group, the end members being located on both ends of the unit cells in the stacking direction; and side plates arranged on side surfaces of the battery group, along the stacking direction, and engaging with the spacers, wherein the side plates have a set of protrusions that bend from the side surfaces along the stacking direction towards the unit cells and engage with the spacers, the set of protrusions being a first protrusion located on the side farther from the mounting surface of the assembled battery and a second protrusion located on the side closer to the mounting surface of the assembled battery, the spacers having a first engagement portion that engages with the first protrusion and a second engagement portion that engages with the second protrusion, and wherein the ratio of a first distance (D1) that is the distance between the first protrusion and the first engagement portion to a second distance (D2) that is the distance between the second protrusion and the second engagement portion is in the range of 0.5 to 2.

0.

2. The battery pack according to claim 1, wherein the length (L1) of the first protrusion is in the range of 0.5 to 2.0 relative to the length (L2) of the second protrusion.

3. The battery pack according to claim 2, wherein the length (L2) of the second protrusion is longer than the length (L1) of the first protrusion.

4. A battery pack comprising: a battery group in which unit cells and spacers are alternately stacked; end members arranged on side surfaces of the battery group, the end members being located on both ends in the stacking direction of the unit cells; and side plates arranged on side surfaces of the battery group, along the stacking direction, and engaging with the spacers, wherein the side plates have a set of protrusions that bend from the side surfaces along the stacking direction towards the battery group and engage with the spacers, the set of protrusions being a first protrusion located on the side farther from the mounting surface of the battery pack and a second protrusion located on the side closer to the mounting surface of the battery pack, and the spacers have a first engagement portion that engages with the first protrusion and a second engagement portion that engages with the second protrusion, and form a space portion that separates the side plates and the unit cells by a predetermined distance.

5. The battery pack according to claim 4, wherein the spacer in the space portion has thick portions at the end adjacent to the first engaging portion and the end adjacent to the second engaging portion, and has a central portion between the thick portions that is thinner than the thick portions.

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