Battery pack

Abstract

To provide a battery pack capable of obtaining sufficient waterproofing.SOLUTION: A battery pack according to an aspect of the present technology includes a plurality of batteries, a holder capable of supporting the plurality of batteries, and an elastic body provided between the batteries and the holder. Each of the batteries has an end face on which a convex positive electrode terminal is formed. The holder has a side plate portion in which a first opening is provided at a location facing the positive electrode terminal. The elastic body includes a sheet portion and a convex portion. The sheet portion is disposed in a region between the end face of the battery and the side plate portion of the holder. The sheet portion has a second opening having a smaller opening diameter than the first opening at a location facing the positive electrode terminal. The convex portion protrudes toward both the side plate portion side and the positive electrode terminal side of the sheet portion, and is configured to contact the side plate portion and the positive electrode terminal.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] This technology relates to a battery pack.

Background Art

[0002] Generally, a battery module having a battery such as a lithium ion secondary battery is used while being housed in a case. If moisture or the like enters the battery module, the battery may malfunction. Therefore, for example, in the invention described in Patent Document 1 below, it has been proposed to provide a rubber ring between the positive electrode terminal and the battery housing portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a battery pack, further improvement in waterproofness is required. It is desirable to provide a battery pack with improved waterproofness.

Means for Solving the Problems

[0005] A battery pack according to one aspect of this technology includes a plurality of batteries, a holder capable of supporting the plurality of batteries, and an elastic body provided between the battery and the holder. Each battery has an end face on which a convex positive electrode terminal is formed. The holder has a side plate portion provided with a first opening at a location facing the positive electrode terminal. The elastic body has a sheet portion and a convex portion. The sheet portion is disposed in a region between the end face of the battery and the side plate portion of the holder. The sheet portion is provided with a second opening having an opening diameter smaller than that of the first opening at a location facing the positive electrode terminal. The convex portion protrudes toward both the side plate portion side and the positive electrode terminal side of the sheet portion and is configured to contact the side plate portion and the positive electrode terminal. [Effects of the Invention]

[0006] In one aspect of this technology, an elastic body is provided between the battery and the holder. The elastic body has protrusions on both the side plate side and the positive terminal side of the sheet portion of the elastic body, as well as convex portions that contact the side plate portion of the holder and the positive terminal of the battery. As a result, the elastic force of the elastic body is used to ensure that the side plate portion of the holder and the convex portions are in close contact, as well as the positive terminal of the battery and the convex portions are in close contact. Consequently, moisture can be prevented from entering the positive terminal. Therefore, sufficient waterproofing can be achieved.

[0007] Furthermore, the effects of this technology are not necessarily limited to those described herein, but may include any of the series of effects related to this technology described later. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a diagram showing an example of a perspective view configuration of a battery pack according to one embodiment of this technology. [Figure 2] Figure 2 shows an example of a perspective view of the battery module housed in the battery pack shown in Figure 1. [Figure 3] Figure 3 shows an example of an unfolded, perspective view of the battery module shown in Figure 2. [Figure 4] Figure 4 shows an example of the cross-sectional configuration of the battery, holder, and elastic waterproof member shown in Figure 3. [Figure 5] Figure 5 shows an example of a perspective view of one end (the positive electrode portion) of the battery shown in Figure 3. [Figure 6] Figure 6 shows an example of a cross-sectional configuration of one end (positive electrode portion) of the battery shown in Figure 3. [Figure 7] Figure 7 shows an example of a cross-sectional configuration of a part of the battery module shown in Figure 2 (the positive electrode portion and its vicinity). [Figure 8] Figure 8 is an enlarged view of a portion of Figure 7. [Figure 9] Figure 9 shows an example of a cross-sectional configuration when the metal tab is removed from the battery module shown in Figure 2. [Figure 10] Figure 10 is a diagram showing an enlarged part of Figure 9. [Figure 11] Figure 11 is a diagram showing a cross-sectional configuration example of the elastic waterproof member in Figure 9. [Figure 12] Figure 12 is a diagram showing an upper surface configuration example of the elastic waterproof member in Figure 11. [Figure 13] Figure 13 is a diagram showing a back surface configuration example of the elastic waterproof member in Figure 11. [Figure 14] Figure 14 is a diagram showing an example of the immersion test results of the battery packs in the comparative example and the example. [Figure 15] Figure 15 is a diagram showing a cross-sectional configuration example of a part (positive electrode part and its vicinity) of the battery module housed in the battery pack according to Comparative Example 1. [Figure 16] Figure 16 is a diagram showing a modified example of the cross-sectional configuration of the elastic waterproof member in Figure 11. [Figure 17] Figure 17 is a diagram showing a modified example of the cross-sectional configuration of the elastic waterproof member in Figure 11. [Figure 18] Figure 18 is a diagram showing a modified example of the cross-sectional configuration of the elastic waterproof member in Figure 11. [Figure 19] Figure 19 is a diagram showing a modified example of the cross-sectional configuration of a part (positive electrode part and its vicinity) of the battery module in Figure 7. [Figure 20] Figure 20 is a diagram showing an example of the immersion test results of the battery packs in the comparative example and the example.

Mode for Carrying Out the Invention

[0009] Hereinafter, the mode for carrying out the present technology will be described in detail with reference to the drawings. The order of description is as follows. 1. Embodiment 1-1. Configuration 1-2. Effect 2. Modified Example 2-1. Modified Example A 2-2. Modified Example B 2-3. Modified Example C 2-4. Modified Example D

[0010] <1. First Embodiment> First, we will describe a battery pack 1, which is one embodiment of this technology.

[0011] The battery pack 1 described here is a power source equipped with multiple batteries and is applicable to a variety of uses, such as electronic devices. The type of battery is not particularly limited and may be either a primary battery or a secondary battery. The type of secondary battery is not particularly limited, but specifically, it may be a lithium-ion secondary battery that obtains battery capacity by utilizing the intercalation and deintercalation of lithium ions. The number of batteries is not particularly limited and can be set arbitrarily. The following description will focus on the case where the batteries are secondary batteries (lithium-ion secondary batteries).

[0012] [1-1. Structure] Figure 1 shows an example of a perspective view of a battery pack 1 according to one embodiment of this technology. Figure 2 shows an example of a perspective view of the contents of the battery pack 1. Figure 3 shows an example of a perspective view of the contents of the battery pack 1 in an unfolded state.

[0013] The battery pack 1 comprises, for example, an outer case 10 and a battery module 20 housed in the outer case 10, as shown in Figures 1 and 2. The battery module 20 has a control board 30. The control board 30 is connected to the positive and negative terminals of each battery 40 (described later) and has circuits for measuring the voltage of each battery 40, detecting the remaining capacity of each battery 40, and measuring the current output from each battery 40 to detect the presence or absence of overcurrent.

[0014] The outer casing 10 is composed of a lower case 10a and an upper case 10b, as shown in Figure 3, for example. The lower case 10a and the upper case 10b are stacked on top of each other to form a housing space for the battery module 20. The outer casing 10 is capable of housing the battery module 20. The outer casing 10 (for example, the lower case 10a) is provided with an external terminal 11 connected to the control board 30. Multiple batteries 40 are connected to the external terminal 11 via the control board 30.

[0015] The outer casing 10 is made of a resin material such as polyethylene (PE), polypropylene (PP), polycarbonate (PC), modified polyphenylene ether (mPPE), polyamide (PA), polybutylene terephthalate (PBT), acrylonitrile-butadiene-styrene copolymer resin (ABS), or polyacetal (POM). The outer casing 10 may also be made of a resin material in which a conductive material such as a metal or conductive filler is dispersed. In this case, the resin material may be one of the resin materials described above.

[0016] The battery pack 1 has a discharge mode in which it supplies power output from the battery module 20 to a load via the external terminal 11. The battery pack 1 may also have a charge mode in which it stores power supplied from a power source connected to the external terminal 11 via the external terminal 11 in the battery module 20. If the battery 40 is a secondary battery, the control board 30 switches between the discharge mode and the charge mode depending on the type of connected object connected to the external terminal 11. If the battery 40 is a primary battery, the control board 30 only performs the discharge mode.

[0017] The battery module 20 has multiple batteries 40 and multiple metal tabs 60. The multiple batteries 40 are electrically connected via the multiple metal tabs 60. For example, some of the multiple batteries 40 are connected in series with each other by the multiple metal tabs 60, and when the multiple batteries 40 connected in series with each other are referred to as a series unit, the multiple series units are connected in parallel with each other by the multiple metal tabs 60. However, the configuration of connection of the multiple batteries 40 is not limited to the above.

[0018] Each metal tab 60 is made of, for example, a metal lead plate. Each battery 40 is either a primary or secondary battery. If each battery 40 is a secondary battery, the type of secondary battery is not particularly limited, but specifically, it could be a lithium-ion secondary battery, which obtains its capacity by utilizing the intercalation and deintercalation of lithium ions. The following description will focus on the case where each battery 40 is a secondary battery (lithium-ion secondary battery). That is, the battery pack 1 described below is a power source equipped with multiple secondary batteries.

[0019] The battery module 20 further has a holder 50 capable of supporting multiple batteries 40. The holder 50 is composed of a pair of holders 50a and 50b, as shown in Figures 3 and 4, for example. Both holders 50a and 50b have a common structure. Figure 4 shows an example of a cross-sectional configuration of holder 50b, battery 40, and elastic waterproof member 70 (described later).

[0020] Each holder 50a and 50b has a side plate portion 51, as shown in Figure 4, for example. The side plate portion 51 of holder 50a and the side plate portion 51 of holder 50b are positioned opposite each other with multiple batteries 40 in between, in the direction in which each battery 40 extends (the direction in which the positive terminal 41 and negative terminal 42 face each other). In holders 50a and 50b, the side plate portion 51 has an opening 52 at a location facing the positive terminal 41 and negative terminal 42 of each battery 40. Therefore, the positive terminal 41 or negative terminal 42 is exposed in the opening 52.

[0021] Each holder 50a and 50b further has a support portion 53 that supports multiple batteries 40 in a layered manner with predetermined gaps between them, as shown in Figure 4, for example. Figure 4 illustrates how the support portion 53 is provided to support multiple batteries 40 in two layers, the lowest and the uppermost layer. A side plate portion 51 is connected to one end of the support portion 53, and the other end of the support portion 53 is an opening 54. The support portion 53 is provided with a housing portion 55 connected to the opening 52 and the opening 54. A portion of the batteries 40 are housed in the housing portion 55.

[0022] Figure 5 shows an example of a perspective view of one end of the battery 40. Figure 6 shows an example of a cross-sectional view of one end of the battery 40.

[0023] As shown in Figures 4 and 5, the battery 40 has a first end face 40a and a second end face 40b facing each other, a positive terminal 41 provided on the first end face 40a, and a negative terminal 42 provided on the second end face 40b. The battery 40 has a cylindrical shape, for example, with the first end face 40a and the second end face 40b extending in directions opposite to each other, and the first end face 40a and the second end face 40b are each circular in shape. The shape of the battery 40 is not limited to a cylindrical shape. The shapes of the first end face 40a and the second end face 40b are not limited to circular shapes.

[0024] The positive electrode terminal 41 is made of a metal material. The positive electrode terminal 41 has a protruding shape (convex portion) on the first end face 40a (see Figure 6). One or more slit portions 43 are provided around the positive electrode terminal 41 on the first end face 40a. A gap is provided on the back side of the positive electrode terminal 41 on the first end face 40a, and this gap is in communication with one or more slit portions 43. A cleavage valve 44 is provided at the bottom of this gap. The cleavage valve 44 has the function of discharging gas generated inside the battery 40 to the outside when the battery 40 overheats abnormally. The negative electrode terminal 42 is made of a metal material. The negative electrode terminal 42 has a flat surface on the second end face 40b.

[0025] Assume that multiple batteries 40 are arranged in a two-dimensional direction (a first direction and a second direction perpendicular to the first direction) that is perpendicular to the longitudinal direction of the batteries 40 (the direction in which the first end face 40a and the second end face 40b of the batteries 40 face each other). In this case, the first end face 40a of one battery 40 (the first battery) and the second end face 40b of another battery 40 (the second battery) in the battery pack 1 are arranged in the same plane. For example, multiple first end faces 40a and multiple second end faces 40b are arranged alternately in at least one of the first direction and the second direction in the same plane. Multiple metal tabs 60 are arranged so as to sandwich the multiple batteries 40 provided in the battery pack 1 from the extending direction of the batteries 40 and face each other.

[0026] In this specification, "extension direction of the battery 40" means the direction parallel to the direction in which the first and second end faces face each other, when the battery 40 is a columnar shape with the first and second end faces extending in directions opposite to each other. In this specification, "arrangement direction of the battery 40" means the direction perpendicular to the direction in which the first and second end faces face each other, when the battery 40 is a columnar shape with the first and second end faces extending in directions opposite to each other.

[0027] Figure 7 shows an example of a cross-sectional configuration of a part of the battery module 20 (the positive terminal 41 and its vicinity). Figure 8 is an enlarged view of a part of Figure 7. Figure 9 shows an example of a cross-sectional configuration when the metal tab 60 is removed from the battery module 20 in Figure 7. Figure 10 is an enlarged view of a part of Figure 9.

[0028] The metal tab 60 is positioned opposite the first end face 40a via the side plate portion 51. The metal tab 60 is electrically connected to the positive terminal 41 on the first end face 40a of the first battery and to the negative terminal 42 on the second end face 40b of the second battery. The metal tab 60 is fixed to the positive terminal 41. The metal tab 60 is fixed to the negative terminal 42. One method for fixing the metal tab 60 to the positive terminal 41 is welding. For example, laser welding or resistance welding can be used for welding. The method for fixing the metal tab 60 to the positive terminal 41 is not limited to the above, and other methods besides welding may be used, such as screw fastening or crimping.

[0029] The metal tab 60 has a protrusion 61 (metal protrusion) that faces the positive terminal 41 and protrudes toward the positive terminal 41. The protrusion 61 is inserted into the opening 52 of the holder 50 and the opening 71a of the elastic waterproof member 70 described later, and is fixed to the upper surface of the positive terminal 41 via the opening 52 of the holder 50 and the opening 71a of the elastic waterproof member 70 described later. Insertion refers to the state in which at least a part of the protrusion 61 is inserted into the opening 52 of the holder 50 and the opening 71a of the elastic waterproof member 70.

[0030] The battery module 20 has an elastic waterproof member 70 provided between the first end face 40a of the battery 40 and the side plate portion 51 of the holder 50, as shown in Figures 4, 7 to 10. The elastic waterproof member 70 is made of a rubber material such as silicone rubber. The rubber material is one specific example of an elastic body. The elastic waterproof member 70 may also be made of an elastic body other than rubber. The elastic waterproof member 70 has a sheet portion 71 and protrusions 72 and 73, as shown in Figures 7 to 10.

[0031] The sheet portion 71 is provided with an opening 71a having a smaller diameter than the opening 52 at a location facing the positive terminal 41. The opening 71a is located within the region facing the opening 52. The protrusion 72 is located on the sheet portion 71 at a position closer to the opening 71a than the protrusion 73, and is located facing the positive terminal 41. The protrusion 73 is located on the sheet portion 71 at a position further from the opening 71a than the protrusion 72, and is located on the first end face 40a at a position not facing the positive terminal 41 (for example, the convex region around the slit portion 43).

[0032] The protrusion 72 protrudes from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71. The protrusion 72 further contacts the side plate portion 51, the positive terminal 41, and the metal tab 60. The protrusion 72 contacts the end of the upper surface of the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51. The upper surface of the positive terminal 41 refers to the surface of the convex-shaped portion of the positive terminal 41 that contacts the metal tab 60. The protrusion 72 is compressed by the positive terminal 41 and the metal tab 60 in a direction that causes the positive terminal 41 and the metal tab 60 to face each other. In addition, the protrusion 72 is compressed by the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 in a direction that causes the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 to face each other. Therefore, the protrusion 72 is in close contact with the side surface (the area enclosed by α in Figure 8) and base portion (the area enclosed by γ in Figure 8) of the protrusion 61 of the metal tab 60, and with the end of the upper surface of the positive electrode terminal 41 (β in Figure 8), as well as with the inner wall of the opening 52 of the side plate portion 51 (the area enclosed by δ in Figure 8). When the elastic waterproof member 70 is removed from the battery module 20, the protrusion 72 has a shape that is vertically symmetrical (symmetrical in the Z-axis direction) with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane).

[0033] The protrusion 72 has protrusions 72a and 72b, as shown in Figures 7 to 10, for example. The protrusion 72a is located closer to the center of the elastic waterproof member 70 (i.e., closer to the opening 71a) when the elastic waterproof member 70 is viewed from above. The protrusion 72b is located further from the center of the elastic waterproof member 70 in relation to the protrusion 72a when the elastic waterproof member 70 is viewed from above. The protrusion 72a protrudes from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71 and is configured to contact the end of the upper surface of the positive terminal 41 and the metal tab 60 (side surface of the protrusion 61). The protrusion 72b protrudes from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71 and is configured to contact the side surface of the opening 52 of the side plate portion 51 and the metal tab 60 (base portion of the metal tab 60). The protrusion 72a is compressed by the positive terminal 41 and the metal tab 60 in a direction that causes the positive terminal 41 and the metal tab 60 to face each other. Similarly, the protrusion 72b is compressed by the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 in a direction that causes the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 to face each other. As a result, the protrusion 72a is in close contact with the side surface of the protrusion 61 of the metal tab 60 (the area enclosed by α in Figure 8) and the end of the upper surface of the positive terminal 41 (the area enclosed by β in Figure 8). The protrusion 72b is in close contact with the base portion of the protrusion 61 of the metal tab 60 (the area enclosed by γ in Figure 8) and the inner wall of the opening 52 of the side plate portion 51 (the area enclosed by δ in Figure 8).

[0034] In the protrusion 72a, the portion of the sheet portion 71 that protrudes toward the side plate portion 51 and the portion of the sheet portion 71 that protrudes toward the positive terminal 41 are positioned opposite each other via the sheet portion 71. In the protrusion 72b, the portion of the sheet portion 71 that protrudes toward the side plate portion 51 and the portion of the sheet portion 71 that protrudes toward the positive terminal 41 are positioned opposite each other via the sheet portion 71. When the elastic waterproof member 70 is removed from the battery module 20, the protrusion 72a has a shape that is vertically symmetrical with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane). When the elastic waterproof member 70 is removed from the battery module 20, the protrusion 72b has a shape that is vertically symmetrical with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane).

[0035] The protrusion 73 has protrusions 73a and 73b, for example, as shown in Figures 7 to 10. The protrusion 73a is located closer to the center of the elastic waterproof member 70 (i.e., closer to the opening 71a) when the elastic waterproof member 70 is viewed from above. The protrusion 73b is located further from the center of the elastic waterproof member 70 in relation to the protrusion 73a when the elastic waterproof member 70 is viewed from above. The protrusions 73a and 73b are configured to protrude from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71, respectively. The protrusions 73a and 73b are configured to be in contact with the side plate portion 51 (the portion enclosed by ε in Figure 8), and furthermore, at least one of the protrusions 73a and 73b is configured to be in contact with the area around the positive terminal 41 (the convex region around the slit portion 43 (the portion enclosed by ζ in Figure 8)). The protrusions 73a and 73b are compressed in a direction in which the side plate portion 51 and the area around the positive terminal 41 (the convex region around the slit portion 43) face each other, by the side plate portion 51 and the area around the positive terminal 41 (the convex region around the slit portion 43). As a result, the protrusions 73a and 73b are in close contact with the side plate portion 51 (the portion enclosed by ε in Figure 8), and furthermore, at least one of the protrusions 73a and 73b is in close contact with the area around the positive terminal 41 (the convex region around the slit portion 43 (the portion enclosed by ζ in Figure 8)).

[0036] In the protrusion 73a, the portion of the sheet portion 71 that protrudes toward the side plate portion 51 and the portion of the sheet portion 71 that protrudes toward the positive terminal 41 are positioned opposite each other via the sheet portion 71. In the protrusion 73b, the portion of the sheet portion 71 that protrudes toward the side plate portion 51 and the portion of the sheet portion 71 that protrudes toward the positive terminal 41 are positioned opposite each other via the sheet portion 71. When the elastic waterproof member 70 is removed from the battery module 20, the protrusion 73a has a shape that is vertically symmetrical with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane). When the elastic waterproof member 70 is removed from the battery module 20, the protrusion 73b has a shape that is vertically symmetrical with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane).

[0037] Figure 11 shows an example of the cross-sectional configuration of the elastic waterproof member 70 when removed from the battery module 20. Figure 12 shows an example of the top surface configuration of the elastic waterproof member 70 in Figure 11. Figure 13 shows an example of the back surface configuration of the elastic waterproof member 70 in Figure 11. The elastic waterproof member 70 has a vertically symmetrical shape with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane), as shown in Figures 11 to 13. Furthermore, the protrusions 72a, 72b, 73a, 73b and the opening 71a are concentric, as shown in Figures 11 to 13. Therefore, there is no distinction between the front and back of the elastic waterproof member 70.

[0038] The heights of the protrusions 72a and 72b are set to account for compression by the positive terminal 41 and the metal tab 60. For example, the height of protrusion 72b is greater than the height of protrusion 72a. The height of protrusion 72a refers to the distance from the vertex P1 of the portion of protrusion 72a provided on the upper surface side of the sheet portion 71 to the vertex P2 of the portion of protrusion 72a provided on the back surface side of the sheet portion 71. The height of protrusion 72b refers to the distance from the vertex P3 of the portion of protrusion 72b provided on the upper surface side of the sheet portion 71 to the vertex P4 of the portion of protrusion 72b provided on the back surface side of the sheet portion 71.

[0039] The heights of the protrusions 73a and 73b are determined to take into account the compression caused by the area around the positive terminal 41 (the convex region around the slit portion 43) and the side plate portion 51. For example, the heights of the protrusions 73a and 73b are equal to each other. The height of the protrusion 73a refers to the distance from the vertex P5 of the portion of the protrusion 73a provided on the upper surface side of the sheet portion 71 to the vertex P6 of the portion of the protrusion 73a provided on the back surface side of the sheet portion 71. The height of the protrusion 73b refers to the distance from the vertex P7 of the portion of the protrusion 73b provided on the upper surface side of the sheet portion 71 to the vertex P8 of the portion of the protrusion 73b provided on the back surface side of the sheet portion 71.

[0040] Next, the waterproofness of the battery pack 1 of the embodiment will be described in comparison with the battery pack of the comparative example. Figure 14 shows the results of the waterproofness test. The battery module housed in the battery pack of comparative example 1 in Figure 14 has the configuration shown in Figure 15, for example. The battery module shown in Figure 15 corresponds to the battery pack 1 of the embodiment in which an elastic waterproof member 170 is provided instead of the elastic waterproof member 70. Except for the fact that the manufacturing lots are different, the configuration of the battery pack 1 is common to all of embodiments 1, 2 and 3.

[0041] The elastic waterproof member 170 is made of a rubber material such as silicone rubber. The rubber material is a specific example of an elastic body. The elastic waterproof member 170 may also be made of an elastic body other than rubber. The elastic waterproof member 170 has a sheet portion 171 and protrusions 172 and 173, as shown in Figure 15, for example.

[0042] The sheet portion 171 is provided with an opening 171a having a smaller diameter than the opening 52 at a location facing the positive terminal 41. The opening 171a is located within the region facing the opening 52. The protrusion 172 is located on the sheet portion 71 at a position closer to the opening 171a than the protrusion 173, and is located facing the positive terminal 41. The protrusion 173 is located on the sheet portion 171 at a position further from the opening 171a than the protrusion 172, and is located on the first end face 40a at a position not facing the positive terminal 41 (for example, the convex region around the slit portion 43).

[0043] The protrusion 172 protrudes only from the side plate portion 51 side of the sheet portion 71 and is in contact with the side plate portion 51, the positive terminal 41, and the metal tab 60. The protrusion 172 is in contact with the end of the upper surface of the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51. The protrusion 172 is compressed by the positive terminal 41 and the metal tab 60 in a direction in which the positive terminal 41 and the metal tab 60 face each other. In addition, the protrusion 172 is compressed by the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 in a direction in which the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 face each other. However, compared to the battery pack 1 of the embodiment, the force compressing the protrusion 172 is weaker because the protrusion 172 does not have a portion that protrudes towards the positive terminal 41 side. Therefore, the protrusion 172 is in light contact with the end of the upper surface of the positive terminal 41, the metal tab 60, and the side surface of the opening 52 of the side plate portion 51.

[0044] The protrusion 172 has, for example, protrusions 172a and 172b, as shown in Figure 15. The protrusion 172a is located closer to the center of the elastic waterproof member 170 (i.e., closer to the opening 171a) when the elastic waterproof member 170 is viewed from above. The protrusion 172b is located further from the center of the elastic waterproof member 170 in relation to the protrusion 172a when the elastic waterproof member 170 is viewed from above. The protrusion 172a protrudes only on the side plate portion 51 side of the sheet portion 171 and is configured to contact the end of the upper surface of the positive terminal 41 and the metal tab 60 (side surface of the protrusion 61). The protrusion 172b protrudes only on the side plate portion 51 side of the sheet portion 171 and is configured to contact the side surface of the opening 52 of the side plate portion 51 and the metal tab 60 (base portion of the metal tab 60). The protrusion 172a is compressed by the positive terminal 41 and the metal tab 60 in a direction that causes the positive terminal 41 and the metal tab 60 to face each other. Similarly, the protrusion 172b is compressed by the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 in a direction that causes the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 to face each other. However, compared to the battery pack 1 of the embodiment, the compressive force on the protrusions 172a and 172b is weaker because there are no portions on the protrusions 172a and 172b that protrude towards the positive terminal 41. Therefore, the protrusions 172a and 172b are in light contact with the end of the upper surface of the positive terminal 41, the metal tab 60, and the side surface of the opening 52 of the side plate portion 51.

[0045] The protrusion 173 has protrusions 173a and 173b, for example, as shown in Figure 15. Protrusion 173a is located closer to the center of the elastic waterproof member 170 (i.e., closer to the opening 171a) when the elastic waterproof member 170 is viewed from above. Protrusion 173b is located further from the center of the elastic waterproof member 170 in relation to protrusion 173a when the elastic waterproof member 170 is viewed from above. Protrusions 173a and 173b are configured to protrude only from the side plate portion 51 side of the sheet portion 171. Protrusions 173a and 173b are configured to be in contact with the side plate portion 51. The protrusions 173a and 173b are compressed in a direction in which the side plate portion 51 and the area around the positive terminal 41 (the convex region around the slit portion 43) face each other, by the area around the side plate portion 51 and the area around the positive terminal 41 (the convex region around the slit portion 43). However, compared to the battery pack 1 of the embodiment, the force compressing the protrusions 173a and 173b is weaker because there is no portion of the protrusions 173a and 173b that protrudes toward the positive terminal 41. Therefore, the protrusions 173a and 173b are in light contact with the side plate portion 51 and the area around the side plate portion 51 and the positive terminal 41 (the convex region around the slit portion 43).

[0046] The method for the water immersion test will now be explained. First, fully charged battery packs (Battery Pack 1 in the Example and Battery Pack in the Comparative Example) were left completely submerged in water for 72 hours. Next, each battery pack was allowed to air dry for 24 hours. After that, the battery packs were disassembled and the positive terminal 41 was observed. If no rust or corrosion was found on the positive terminal 41, the waterproof test was deemed to have passed. On the other hand, if rust or corrosion was found on the positive terminal 41, the waterproof test was deemed to have failed.

[0047] Figure 14 shows that all samples of battery pack 1 in Examples 1, 2, and 3 passed the waterproofing test. This indicates that high waterproofing performance is achieved through the action of the elastic waterproofing member 70. On the other hand, in Comparative Example 1, five out of 30 samples of the battery pack failed the waterproofing test.

[0048] <1-2. Effects> Next, I will explain the effects of battery pack 1.

[0049] Generally, battery modules containing batteries such as lithium-ion secondary batteries are used while housed in a case. If moisture or other substances enter the battery module, the battery may malfunction. Therefore, for example, the invention described in Patent Document 1 above proposes providing a rubber ring between the positive electrode terminal and the battery housing. However, there is a demand for further improvement in waterproofing of battery packs.

[0050] On the other hand, in this embodiment, an elastic waterproof member 70 is provided between the battery 40 and the holder 50. The elastic waterproof member 70 has protrusions 72 that extend from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71, and that contact the side plate portion 51 and the positive terminal 41. As a result, the elastic force of the elastic material is used to ensure that the side plate portion 51 and the protrusions 72 are in close contact, and the positive terminal 41 and the protrusions 72 are in close contact. As a result, it is possible to prevent moisture from entering the positive terminal 41. Therefore, sufficient waterproofing can be obtained.

[0051] Furthermore, in this embodiment, the protrusion 72 is in contact with the end of the upper surface of the positive terminal 41 and also in contact with the side surface of the opening 52. As a result, the elastic force of the elastic material is utilized to ensure that the end of the upper surface of the positive terminal 41 and the protrusion 72 are in close contact, as is the side surface of the opening 52 of the side plate portion 51 and the protrusion 72. Consequently, moisture can be prevented from entering the positive terminal 41. Therefore, sufficient waterproofing can be obtained.

[0052] Furthermore, in this embodiment, the protrusion 72 has a shape that is vertically symmetrical with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane). As a result, the elastic waterproof member 70 has no front or back side, eliminating the need to check the front and back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1. Consequently, the labor required to check the front and back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1 can be eliminated, and the inspection device for checking the front and back of the elastic waterproof member 70 can also be omitted.

[0053] Furthermore, in this embodiment, the protrusion 72a protrudes from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71 and is in contact with the end of the upper surface of the positive terminal 41, and the protrusion 72b protrudes from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71 and is in contact with the side surface of the opening 52 of the side plate portion 51. As a result, the protrusion 72 is compressed by the positive terminal 41 and the metal tab 60 in a direction in which the positive terminal 41 and the metal tab 60 face each other. Also, the protrusion 72 is compressed by the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 in a direction in which the positive terminal 41 and the side surface of the opening 52 of the side plate portion 51 face each other. As a result, the protrusion 72 is in close contact with the end of the upper surface of the positive terminal 41 and also in close contact with the side surface of the opening 52 of the side plate portion 51. Therefore, it is possible to prevent moisture from entering the positive terminal 41, and sufficient waterproofing can be obtained.

[0054] Furthermore, in this embodiment, the protrusion 72a is positioned such that the portion of the sheet portion 71 protruding toward the side plate portion 51 and the portion of the sheet portion 71 protruding toward the positive terminal 41 are opposite each other via the sheet portion 71. In addition, the protrusion 72b is positioned such that the portion of the sheet portion 71 protruding toward the side plate portion 51 and the portion of the sheet portion 71 protruding toward the positive terminal 41 are opposite each other via the sheet portion 71. As a result, the elastic waterproof member 70 has no front or back side, eliminating the need to check the front or back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1. Consequently, the labor required to check the front or back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1 can be eliminated, and the inspection device for checking the front or back of the elastic waterproof member 70 can also be omitted.

[0055] Furthermore, in this embodiment, the protrusions 72a and 72b are vertically symmetrical with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane). As a result, the elastic waterproof member 70 has no front or back side, eliminating the need to check the front and back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1. Consequently, the labor required to check the front and back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1 can be eliminated, and the inspection device for checking the front and back of the elastic waterproof member 70 can also be omitted.

[0056] Furthermore, in this embodiment, the height of the protrusion 72b from the sheet portion 71 is greater than the height of the protrusion 72a from the sheet portion 71. This makes it possible to make the shape of the protrusions 72a and 72b closer to the shape of the gap formed between the positive electrode terminal 41 and the side plate portion 51 when the protrusions 72a and 72b are sandwiched between the positive electrode terminal 41 and the side plate portion 51. As a result, the protrusions 72a and 72b can be compressed relatively evenly, and the adhesion between the protrusions 72a and 72b and the positive electrode terminal 41 and the side plate portion 51 can be improved. Therefore, it is possible to prevent moisture from entering the positive electrode terminal 41, and thus sufficient waterproofing can be obtained.

[0057] Furthermore, in this embodiment, the protrusion 72 is also in contact with the metal tab 60. This allows the protrusion 72 and the metal tab 60 to be in close contact, thus providing a higher level of waterproofing than when the protrusion 72 is not in contact with the metal tab 60.

[0058] Furthermore, in this embodiment, the protrusion 72a is in contact with the end of the upper surface of the positive terminal 41 and the metal tab 60, and the protrusion 72b is in contact with the side surface of the opening 52 of the side plate portion 51 and the metal tab 60. As a result, the elastic force of the elastic material is used to ensure that the end of the upper surface of the positive terminal 41 and the metal tab 60 are in close contact, and that the side surface of the opening 52 of the side plate portion 51 and the metal tab 60 are in close contact. As a result, it is possible to prevent moisture from entering the positive terminal 41. Therefore, sufficient waterproofing can be obtained.

[0059] Furthermore, in this embodiment, the protrusion 72a is in contact with the side surface of the protrusion 61, and the protrusion 72b is in contact with the base portion of the metal tab 60 that is attached to the protrusion 61. As a result, the elastic force of the elastic material is utilized to ensure that the protrusion 72a and the side surface of the protrusion 61 are in close contact, and the protrusion 72b and the base portion of the metal tab 60 that is attached to the protrusion 61 are in close contact. Consequently, moisture can be prevented from entering the positive electrode terminal 41. Therefore, sufficient waterproofing can be obtained.

[0060] Furthermore, in this embodiment, the height of the protrusion 72b from the sheet portion 71 is greater than the height of the protrusion 72a from the sheet portion 71. This makes it possible to approximate the shape of the protrusions 72a and 72b to the shape of the gap formed between the positive electrode terminal 41 and the metal tab 60 when the protrusions 72a and 72b are sandwiched between the positive electrode terminal 41 and the metal tab 60. As a result, the protrusions 72a and 72b can be compressed relatively evenly, improving the adhesion between the protrusions 72a and 72b and the metal tab 60. Therefore, it is possible to prevent moisture from entering the positive electrode terminal 41, and thus sufficient waterproofing can be obtained.

[0061] Furthermore, in this embodiment, the elastic waterproof member 70 has a vertically symmetrical shape with respect to the sheet portion 71 in a vertical cross-section (cross-section in the XZ plane). As a result, the elastic waterproof member 70 has no front or back side, eliminating the need to check the front and back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1. Consequently, the labor required to check the front and back of the elastic waterproof member 70 during the manufacturing process of the battery pack 1 can be eliminated, and the inspection device for checking the front and back of the elastic waterproof member 70 can also be omitted.

[0062] Furthermore, in this embodiment, the elastic waterproof member 70 is made of rubber. As a result, the elastic force of the elastic waterproof member 70 causes the positive electrode terminal 41 to adhere tightly to the side plate portion 51 or the metal tab 60. Consequently, it is possible to prevent moisture from entering the positive electrode terminal 41. Therefore, sufficient waterproofing can be obtained.

[0063] <2. Variant> Next, a modified example of the battery pack 1 according to the above embodiment will be described.

[0064] <2-1. Variation A> In the above embodiment, the protrusion 73 may have three or more protrusions that project from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71. In the above embodiment, for example, as shown in Figure 16, the protrusion 73 may have three protrusions 73a, 73b, and 73c that project from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71. For example, as shown in Figure 16, the protrusion 73c is provided at a position further away from the center of the elastic waterproof member 70 in relation to the protrusions 73a and 73b. Even in this case, similar to the above embodiment, the protrusion 73 can be brought into close contact with the periphery of the side plate portion 51 and the positive terminal 41 (the convex region around the slit portion 43). As a result, it is possible to prevent moisture from entering the positive terminal 41. Therefore, sufficient waterproofing can be obtained.

[0065] <2-2. Variation B> In the above embodiment, the elastic waterproof member 70 may have an asymmetrical shape in the vertical cross-section (cross-section in the XZ plane) with respect to the sheet portion 71.

[0066] In the protrusion 72b, for example, as shown in Figure 17, the portion of the sheet portion 71 that protrudes toward the side plate portion 51 and the portion of the sheet portion 71 that protrudes toward the positive terminal 41 may be positioned so that they do not directly face each other via the sheet portion 71. This is permissible insofar as the portion of the sheet portion 71 that protrudes toward the side plate portion 51 can be in close contact with the base portion of the protrusion 61 of the metal tab 60 (the portion enclosed by γ in Figure 8) and the inner wall of the opening 52 of the side plate portion 51 (the portion enclosed by δ in Figure 8).

[0067] Similarly, in the convex portions 73a and 73b, for example, as shown in Figure 17, the portion of the sheet portion 71 that protrudes toward the side plate portion 51 and the portion of the sheet portion 71 that protrudes toward the positive terminal 41 may be positioned so as not to be directly opposite each other via the sheet portion 71. This is permissible as long as the convex portions 73a and 73b are configured to be in contact with the side plate portion 51 (the portion enclosed by ε in Figure 8), and furthermore, at least one of the convex portions 73a and 73b is configured to be in contact with the periphery of the positive terminal 41 (the convex region around the slit portion 43 (the portion enclosed by ζ in Figure 8)).

[0068] Thus, in this modified example, the elastic waterproof member 70 has an asymmetrical shape in the vertical cross-section (cross-section in the XZ plane) with respect to the sheet portion 71, within a range that does not impair the adhesion between the protrusion 72b and the metal tab 60 and the side plate portion 51, and the adhesion between the protrusions 73a, 73b and the area around the side plate portion 51 and the positive terminal 41 (the convex region around the slit portion 43). Therefore, sufficient waterproofing can be obtained, as in the above embodiment.

[0069] In this modified example, the heights of the protrusions 72a and 72b are set to account for compression by the positive terminal 41 and the metal tab 60. For example, the height of the protrusion 72b is greater than the height of the protrusion 72a. In this modified example, the height of the protrusion 72a refers to the distance between a plane F1 parallel to the sheet portion 71, which includes vertex P1, and a plane F2 parallel to the sheet portion 71, which includes vertex P2. In this modified example, the height of the protrusion 72b refers to the distance between a plane F3 parallel to the sheet portion 71, which includes vertex P3, and a plane F4 parallel to the sheet portion 71, which includes vertex P4.

[0070] The heights of the protrusions 73a and 73b are determined considering the compression caused by the area around the positive terminal 41 (the convex region around the slit portion 43) and the side plate portion 51. For example, the heights of the protrusions 73a and 73b are equal to each other. The height of the protrusion 73a refers to the distance between the plane F5, which includes vertex P5 and is parallel to the sheet portion 71, and the plane F6, which includes vertex P6 and is parallel to the sheet portion 71. The height of the protrusion 73b refers to the distance between the plane F7, which includes vertex P7 and is parallel to the sheet portion 71, and the plane F8, which includes vertex P8 and is parallel to the sheet portion 71.

[0071] <2-3. Modified form C> In the above embodiment, the protrusion 72 may be composed of a single protrusion that protrudes from both the side plate portion 51 side and the positive terminal 41 side of the sheet portion 71, as shown in Figure 18. Even in this case, the protrusion 72 is in close contact with the side surface of the protrusion 61 of the metal tab 60 (the portion enclosed by α in Figure 8) and the base portion (the portion enclosed by γ in Figure 8), as well as the end of the upper surface of the positive terminal 41 (β in Figure 8), and also in close contact with the inner wall of the opening 52 of the side plate portion 51 (the portion enclosed by δ in Figure 8). As a result, it is possible to prevent moisture from entering the positive terminal 41. Therefore, sufficient waterproofing can be obtained, as in the above embodiment.

[0072] <2-4. Modification D> In the above embodiment, the metal tab 60 may have one or more slits 62 in the protrusion 61, for example, as shown in Figure 19. When one or more slits 62 are provided in the protrusion 61, there is a risk that moisture or the like may enter the positive electrode terminal 41 through the one or more slits 62. However, an elastic waterproof member 70 is provided between the one or more slits 62 and the inside of the positive electrode terminal 41. This prevents moisture from entering the positive electrode terminal 41. Therefore, sufficient waterproofing can be obtained.

[0073] Next, the waterproofness of the battery pack 1 of Example 4 (Modified Example D) will be described in comparison with the battery pack of Comparative Example 2. Figure 20 shows the results of a waterproofness test conducted with a slit provided in the metal tab 60. The battery pack of Comparative Example 2 is configured in which a slit is provided in the metal tab 60 as in the battery pack of Comparative Example 1. The battery pack 1 of Example 4 (Modified Example D) is configured in which a slit 62 is provided in the metal tab 60 as in the battery pack of Example 1. The method of the waterproofness test is the same as the method described in <1. First Embodiment>.

[0074] Figure 20 shows that all samples of the battery pack 1 in Example 4 passed the waterproof test. This indicates that even when a slit 62 is provided in the metal tab 60, high waterproof performance is achieved through the action of the elastic waterproof member 70. On the other hand, in the battery pack of Comparative Example 2, it can be seen that moisture entered through the slit 62 in the metal tab 60 in 14 out of 30 samples.

[0075] Although the present technology has been described above with reference to one embodiment, the present technology is not limited to the embodiments described above, and various modifications are possible with respect to the present technology.

[0076] For example, lithium was used as the electrode reactant for the secondary battery, but the type of electrode reactant is not particularly limited. Specifically, the electrode reactant may be any other Group 1 element in the long-period periodic table, such as sodium and potassium, or any Group 2 element in the long-period periodic table, such as magnesium and calcium, or any other light metal such as aluminum.

[0077] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur. [Explanation of Symbols]

[0078] 1...Battery pack, 10...Outer case, 10a...Lower case, 10b...Upper case, 11...External terminal, 20...Battery module, 30...Control board, 40...Battery, 40a...First end face, 40b...Second end face, 41...Positive terminal, 42...Negative terminal, 43...Slit section, 44...Opening valve, 50, 50a, 50b...Holder, 51...Side plate section, 52...Opening, 53...Support section, 54...Opening, 55...Housing section, 60...Metal tab, 61...Protrusion, 62...Slit, 70...Elastic waterproof member, 71...Sheet section, 71a...Opening, 72, 72a, 72b, 73, 73a, 73b, 73c...Protrusion, P1, P2, P3, P4, P5, P6, P7, P8...Vertex.

Claims

1. Multiple batteries, A holder capable of supporting the aforementioned plurality of batteries, An elastic body provided between the battery and the holder Equipped with, Each of the batteries has an end face on which a convex positive electrode terminal is formed, The holder has a side plate portion having a first opening at a location facing the positive terminal, The elastic body is A sheet portion is provided in the region between the end face and the side plate portion, and a second opening with a smaller diameter than the first opening is provided at the location facing the positive terminal, The sheet portion has protrusions on both the side plate portion side and the positive terminal portion side, and the protrusions are in contact with the side plate portion and the positive terminal portion. has Battery pack.

2. The protrusion is in contact with the end of the upper surface of the positive terminal and also in contact with the inner wall of the first opening. The battery pack according to claim 1.

3. The aforementioned protrusion has a shape that is vertically symmetrical with respect to the sheet portion in a vertical cross-section. The battery pack according to claim 1.

4. The aforementioned protrusion is, The first protrusion protrudes from both the side plate portion and the positive terminal portion of the sheet portion and contacts the end of the upper surface of the positive terminal, The second protrusion protrudes from both the side plate portion and the positive terminal portion of the sheet portion and is in contact with the side surface of the first opening. has The battery pack according to claim 1.

5. In the first protrusion, the portion of the sheet portion that protrudes toward the side plate portion and the portion of the sheet portion that protrudes toward the positive terminal portion are provided in positions that face each other via the sheet portion. In the second protrusion, the portion of the sheet portion that protrudes toward the side plate portion and the portion of the sheet portion that protrudes toward the positive terminal portion are positioned opposite each other via the sheet portion. The battery pack according to claim 4.

6. The first protrusion has a shape that is vertically symmetrical with respect to the sheet portion in a vertical cross-section. The second protrusion has a shape that is vertically symmetrical with respect to the sheet portion in a vertical cross-section. The battery pack according to claim 5.

7. The height of the second protrusion is greater than the height of the first protrusion. The battery pack according to claim 6.

8. The system further includes a metal tab positioned opposite the end face via the side plate portion, which electrically connects the plurality of batteries and is fixed to the positive terminal, The aforementioned protrusion is also in contact with the metal tab. The battery pack according to claim 1.

9. The system further includes a metal tab positioned opposite the end face via the side plate portion, which electrically connects the plurality of batteries and is fixed to the positive terminal, The first protrusion is in contact with the end of the upper surface of the positive terminal and the metal tab. The second protrusion is in contact with the side surface of the first opening and the metal tab. The battery pack according to claim 4.

10. The metal tab has a metal protrusion that is fixed to the positive terminal through the first opening and the second opening, The first protrusion is in contact with the side surface of the metal protrusion. The second protrusion is in contact with the base portion of the metal tab. The battery pack according to claim 9.

11. The height of the second protrusion is greater than the height of the first protrusion. The battery pack according to claim 10.

12. The elastic body has a shape that is symmetrical vertically with respect to the sheet portion in a vertical cross-section. The battery pack according to claim 1.

13. The elastic body is made of rubber. The battery pack according to claim 1.

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