Battery pack

Abstract

In this battery pack (1h), a plurality of batteries are housed in a case (10e). The plurality of batteries have a battery safety valve that opens due to an increase in the internal pressure and exhausts internal gas, and are immersed in cooling liquid while being held by a battery holder (60a) within the case (10e). An exhaust hole (13) is provided in a lateral side surface of the case (10e). A pack safety valve is provided on the outer side, on the lateral side surface of the case (10e). Inside the case (10e), provided in a portion covering the exhaust hole (13) is a pocket part (96) having an opening (P) at the upper end thereof and being closed at the lower end thereof. The pocket part (96) is formed so as to include a part of the battery holder (60a) and a part of the case (10e), and a part of the battery holder forms a wall of the pocket part.

Description

Battery pack

[0008] ,

[0001] The present disclosure relates to a battery pack in which a plurality of batteries are housed in a case.

[0002] Secondary batteries such as lithium-ion batteries are used in the form of a battery pack in which a plurality of batteries are electrically connected and housed in a case. Patent Document 1 discloses a battery pack in which a plurality of batteries are housed in a space filled with a coolant having insulating properties and the plurality of batteries are cooled.

[0003] Japanese Patent Application Laid-Open No. 2014-60088

[0004] By the way, when there is an abnormality in the battery in the battery pack, heat is generated inside the battery, and the surface of the exterior body of the battery becomes high temperature. And when the abnormality further progresses, eventually high-temperature gas is generated from inside the battery. In the battery pack disclosed in Patent Document 1, it is conceivable to provide a battery safety valve that opens due to an increase in internal pressure in the battery. In this case, an exhaust hole for exhausting the gas exhausted from the battery safety valve is provided on the side surface of the case of the battery pack, and a pack safety valve that exhausts when the internal pressure of the gas in the case rises to a predetermined value or more is provided at a position covering the exhaust hole.

[0005] However, in the configuration in which the pack safety valve is provided as described above, when the battery undergoes thermal runaway and the pack safety valve is opened, the coolant may flow out from the opened pack safety valve, and the liquid level of the coolant may drop to the position of the safety valve. In this case, the thermal runaway battery cannot be sufficiently immersed in the coolant, so the thermal runaway battery is not sufficiently cooled, and there is a possibility that thermal runaway may spread among the plurality of batteries in the battery pack.

[0006] Also, in the battery case, suppressing a decrease in the space available for battery arrangement is important for suppressing a decrease in the volumetric energy density of the battery pack.

[0007] An object of the present disclosure is to provide a battery pack that can suppress the outflow of the coolant when the pack safety valve is opened and can suppress a decrease in the volumetric energy density in a configuration in which the pack safety valve is provided on the lateral side surface of the case.

[0008] One aspect of the present disclosure is a battery pack in which a plurality of batteries are housed in a case, the plurality of batteries having battery safety valves that open when the internal pressure rises and exhaust the gas inside, and are immersed in a coolant while being held in a battery holder within the case, the case has exhaust holes on its lateral sides, and a pack safety valve is provided on the outside of the lateral sides of the case that opens when the internal pressure rises and exhausts the gas from the exhaust holes, and on the inside of the case, a cylindrical pocket portion is provided in the portion covering the exhaust holes, having an opening at the upper end and a closed lower end, the pocket portion is formed by including a part of the battery holder and a part of the case, and the part of the battery holder forms the wall of the pocket portion.

[0009] According to one embodiment of the present disclosure, a cylindrical pocket portion is provided inside the case, covering the exhaust vent, with an opening at the upper end and a closed lower end. Therefore, when the pack safety valve is opened and the coolant inside the case is discharged to the outside of the case through the exhaust vent, the coolant flowing from inside the case towards the exhaust vent can be blocked by the wall of the pocket. This prevents a significant decrease in the height of the coolant present in the battery placement space inside the case. For this reason, in a configuration where the pack safety valve is provided on the lateral side of the case, the outflow of coolant when the pack safety valve is opened can be suppressed. Furthermore, the pocket portion is formed including a part of the battery holder and a part of the case, and a part of the battery holder forms the wall of the pocket portion. As a result, there is no need to form a separate wall for the battery holder adjacent to the pocket portion in the lateral direction, thus preventing a reduction in the space for placing batteries inside the case. Therefore, a decrease in volumetric energy density can be suppressed.

[0010] This is a schematic perspective view of a battery pack, which is an example of an embodiment. This is a perspective view of the case constituting the battery pack of the embodiment, with some parts omitted and the cover removed. This is a cross-sectional view taken along line A-A in Figure 1 when the pack safety valve is closed in the battery pack of the embodiment. This is an enlarged view showing the specific configuration of the battery block shown in Figure 3. This is a cross-sectional view of the batteries constituting the battery block shown in Figure 4. This is a diagram corresponding to Figure 3 when the pack safety valve is open in the battery pack of the embodiment. This is a diagram corresponding to Figure 3 when the pack safety valve is closed in the battery pack of the comparative example. This is a diagram corresponding to Figure 7 when the pack safety valve is open in the comparative example. This is an enlarged view corresponding to the pack safety valve side end of Figure 3 in another example of the embodiment. This is an enlarged view corresponding to the pack safety valve side end of Figure 3 in another example of the embodiment. This is an enlarged perspective view of the exhaust port side end of the battery pack of another example of the embodiment with the cover removed. This is an enlarged perspective view showing the section D-D in Figure 11. This is an enlarged perspective view of the exhaust port side end of the battery pack of another example of the embodiment with the cover removed. This is an enlarged perspective view showing the section E-E in Figure 13. This is an enlarged perspective view of the exhaust port side end of a battery pack in another embodiment with the cover removed. This is an enlarged perspective view showing the F-F cross-section in Figure 15. This is an enlarged perspective view of the exhaust port side end of a battery pack in another embodiment with the cover removed. This is an enlarged perspective view showing the G-G cross-section in Figure 17.

[0011] The embodiments relating to this disclosure will be described in detail below with reference to the attached drawings. Note that the drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. Furthermore, among the components described below, those components that are not described in the independent claim representing the highest-level concept are optional components and not essential components.

[0012] Furthermore, in the following embodiments, the case in which the battery pack 1 has a substantially rectangular parallelepiped shape will be described as an example. In the drawings and the description of the embodiments, the X direction indicates the longitudinal direction of the battery pack 1 (case 10), the Y direction indicates the width direction of the battery pack 1 (case 10), and the Z direction indicates the vertical direction (height direction) of the battery pack 1 (case 10). The X, Y, and Z directions are orthogonal to each other. Also, in the Z direction, the side on which the cap 45 of the battery 30 shown in Figure 4 is provided is referred to as the "upper side," and the opposite side is referred to as the "lower side." The longitudinal direction, which is the X direction, corresponds to the first direction. The width direction, which is the Y direction, corresponds to the second direction.

[0013] The general outline of the battery pack 1 will be described with reference to Figures 1 to 4. Figure 1 is a schematic perspective view of a battery pack 1, which is an example of an embodiment. Figure 2 is a perspective view of the case constituting the battery pack 1, with some parts omitted and the cover 15 removed. Figure 3 is a cross-sectional view of Figure 1 taken along line A-A (a cross-sectional view taken when the battery pack 1 is cut along the XZ plane passing through the center in the width direction) when the pack safety valve 82 is closed. Figure 4 is an enlarged view showing the specific configuration of the battery block 20 shown in Figure 3.

[0014] The battery pack 1 comprises a battery block 20 having a plurality of batteries 30 (Figure 4) and a case 10 housing the battery block 20. The batteries 30 are, for example, non-aqueous electrolyte secondary batteries such as lithium-ion batteries, and are not particularly limited in shape or size, but cylindrical batteries are preferred. The following description will focus on the case where the batteries 30 are cylindrical batteries.

[0015] The case 10 is a box shape with a roughly rectangular parallelepiped exterior. An insulating coolant 50 is stored inside the case 10, and at least a portion of the outer surface of each battery 30 is immersed in the coolant 50. As a result, the coolant 50 is in direct contact with each battery 30, improving the cooling performance of each battery 30. Furthermore, as will be described later, when a malfunction occurs in the battery 30, the gas generated from inside the battery 30 passes through the coolant 50 storage area inside the case 10, thus lowering the gas temperature when the gas is exhausted outside the case 10.

[0016] Battery pack 1 is primarily used as a power source. For example, battery pack 1 is used as a power source for motor-driven electric equipment such as electric vehicles, power tools, electric assist bicycles, electric motorcycles, electric wheelchairs, electric tricycles, and electric carts. However, the use of battery pack 1 is not limited, and it may also be used as a power source for various electrical equipment other than electric equipment, such as vacuum cleaners, wireless devices, lighting devices, digital cameras, and video cameras used both indoors and outdoors.

[0017] As shown in Figure 4, the battery block 20 includes a plurality of batteries 30 and a battery holder 60 that inserts and holds both ends of the plurality of batteries 30 in the vertical direction Z.

[0018] Each of the multiple batteries 30 has a battery safety valve 37 that opens when the internal pressure rises and exhausts the gas inside. As will be described in detail later, in this embodiment the battery safety valve 37 is provided at the upper end of the battery 30. The multiple batteries 30 are arranged vertically within the case 10 so that the battery safety valve 37 is located at the upper end. When a malfunction occurs in a battery 30 and the internal pressure of the battery 30 rises, gas is exhausted from the exhaust hole 45a (see Figure 5, described later) formed in the cap 45 that constitutes the battery safety valve 37.

[0019] The battery holder 60 includes an upper holder 61 that holds the upper part of the battery 30 and a lower holder 62 that holds the lower part of the battery 30. The upper holder 61 includes a holding portion 63 that holds the upper end of the battery 30 and an opening 64 into which the cap 45 of the battery 30 is inserted, exposing the cap 45 to the coolant reservoir in the case 10. The cap 45 constitutes the battery safety valve 37. The lower holder 62 includes a holding portion 65 that holds the lower end of the battery 30 and an opening 66 that connects to the inside of the holding portion 65 and exposes the lower end surface of the battery 30.

[0020] Case 10 will be explained in detail with reference to Figures 1 to 3.

[0021] The case 10 is made of a metal such as aluminum or resin, and has a roughly rectangular shape. Specifically, the case 10 has a roughly rectangular shape and houses a plurality of batteries 30.

[0022] The case 10 is composed of a main body member 91 which is a roughly rectangular parallelepiped with an opening at its upper end, and a lid 15 which closes the opening at the upper end of the main body member 91. The lid 15 is a roughly rectangular plate. A positive electrode terminal 71 and a negative electrode terminal 72 protrude from both sides in the width direction of one longitudinal side surface of the main body member 91, which is the lateral side surface. The positive electrode terminal 71 and the negative electrode terminal 72 correspond to electrode terminals. The positive electrode terminal 71 is connected to a positive electrode terminal plate described later inside the case 10. The negative electrode terminal 72 is connected to a negative electrode terminal plate described later inside the case 10. Thus, one longitudinal side surface of the case 10 corresponds to the terminal protrusion side. On both sides in the width direction of one longitudinal side surface of the case body 11, an inlet port 73 for the inflow of coolant into the case 10 and an outlet port 74 for the outflow of coolant from the case 10 protrude from below the positive electrode terminal 71 and the negative electrode terminal 72, respectively. Coolant piping, which constitutes a coolant path (not shown), is connected to the ends of each port 73, 74. The coolant path is provided with a coolant reservoir and a pump for supplying coolant from the reservoir into the case body. The inlet port 73 may be located on the negative terminal 72 side, and the outlet port 74 on the positive terminal 71 side. Alternatively, the inlet port 73 may be located above the positive terminal 71 or negative terminal 72, and the outlet port 74 may be located below the positive terminal 71 or negative terminal 72. Conversely, the inlet port 73 may be located below the positive terminal 71 or negative terminal 72, and the outlet port 74 may be located above the positive terminal 71 or negative terminal 72. Furthermore, the inlet port 73 and the outlet port 74 may be located above the positive terminal 71 and the negative terminal 72, respectively.

[0023] The main body member 91 has two first side walls 91a and 91b located at both ends in the longitudinal direction X, two second side walls 91c located at both ends in the width direction Y, and a bottom plate portion 91d provided at the lower end that closes the lower inner end of the main body member 91. Each of the side walls 91a, 91b, and 91c corresponds to a wall portion. The case 10 has the function of protecting the battery 30 housed inside from dust and water.

[0024] As shown in Figures 3 and 4, the battery block 20 is housed inside the case 10, and the portion of the multiple batteries 30 constituting the battery block 20, including the middle portion in the vertical Z direction, is immersed in the coolant 50. From the viewpoint of efficiently cooling the batteries 30, it is preferable that the coolant 50 fills almost the entire interior of the case body 11. In this way, the batteries 30 are in contact with the coolant 50 and cooled directly, so the batteries 30 can be cooled efficiently. This improves the charging performance, durability, and safety of the batteries 30.

[0025] Furthermore, when multiple battery packs are combined to form a more advanced battery system, battery pack 1 may sometimes be referred to as a battery module.

[0026] The coolant 50 has insulating properties. This prevents battery 30 from leaking electricity to other batteries 30 via the coolant 50. Examples of coolant 50 include insulating oil, transformer oil, silicone oil, and fluorine-based inert liquids such as hydrofluoroether.

[0027] As shown in Figures 3 and 4, a gap is formed between the battery safety valve 37 of the battery 30 and the lower surface of the lid 15 at the upper end of the inside of the case 10. The cap 45 that constitutes the battery safety valve 37 is exposed in this gap. As a result, when a malfunction occurs in the battery 30 and the internal pressure of the battery 30 rises, the battery safety valve 37 opens, and the gas generated inside the battery 30 is exhausted through the exhaust hole 45a (see Figure 5) of the cap 45. The gas exhausted from the cap 45 of the battery safety valve 37 is then exhausted to the outside of the case 10 through the exhaust hole 13 when the pack safety valve 82, described later, opens.

[0028] An exhaust hole 13 is formed in the middle of the width Y and vertical Z portion of one side surface of the case 10 in the longitudinal direction X (front side surface in Figure 1, left side surface in Figures 2 and 3). The exhaust hole 13 is formed to penetrate the first side wall 91a at one end in the longitudinal direction X of the main body member 91 that constitutes the case 10 in the longitudinal direction X. The exhaust hole 13 exhausts the gas inside the case 10 to the outside of the case 10.

[0029] As shown in Figures 1 and 3, a pack safety valve 82 is provided on the outer side of the lateral surface of the first side wall 91a so as to cover the exhaust hole 13. The pack safety valve 82 is configured such that, for example, the valve body is biased by a spring so as to elastically close the exhaust hole 13. When the internal pressure in the protrusion 12 rises, the valve body moves against the force to open the exhaust hole 13, so the pack safety valve 82 opens. As a result, when a malfunction occurs in the battery 30, the gas exhausted from the battery safety valve 37 is exhausted to the outside of the case 10 through the exhaust hole 13 by the opening of the pack safety valve 82. Also, under normal conditions when there is no malfunction in the battery 30, the pack safety valve 82 is closed so that the coolant inside the case 10 does not leak out of the case 10 through the exhaust hole 13. Furthermore, on the inside of the case 10, a pocket portion 93, which will be described later, is provided in the portion covering the exhaust hole 13, and is a roughly rectangular cylindrical shape with an opening P at the upper end and a closed lower end.

[0030] The battery block 20 will be described with reference to Figure 4. As described above, the battery block 20 has a battery holder 60 into which multiple batteries 30 are inserted and held at both axial ends.

[0031] The battery holder 60 is constructed by combining and fixing an upper holder 61 and a lower holder 62 in the vertical direction, with a plurality of batteries 30 sandwiched inside each other. The upper holder 61 has a holding portion 63 and an opening 64 as described above. The lower holder 62 has a holding portion 65 and an opening 66 as described above. The upper holder 61 and the lower holder 62 may be combined by a fitting portion (not shown) or locked together by a locking portion (not shown). The upper holder 61 and the lower holder 62 may be fixed together by fastening means including screws. The positive terminal plate 70 abuts against the upper surface of the upper holder 61. The negative terminal plate 80 abuts against the lower surface of the lower holder 62.

[0032] The battery holder 60 may be made of, for example, PC (polycarbonate) resin, high thermal conductivity PPS (polyphenylene sulfide) resin, resin containing a heat dissipation filler, or injection-molded thermosetting resin. More specifically, the battery holder 60 may be made of phenolic resin, unsaturated polyester, or unsaturated polyester mixed with a heat absorbent.

[0033] The holding portion 63 of the upper holder 61 is a circular hole formed on the lower surface of the upper holder 61. The upper end of the battery 30 is held by being fitted into the holding portion 63. The opening 64 is formed at the center of the holding portion 63 so as to penetrate the upper holder 61 in the vertical direction. The opening 64 is, for example, a hole with a circular cross-section. The cap 45 of the upper end of the battery 30 is exposed within the opening 64. The positive electrode terminal plate 70 and the cap 45 of the battery 30 are electrically connected via a positive electrode lead portion (not shown). The positive electrode lead portion may be a connecting lead portion formed integrally with the positive electrode terminal plate 70 and extending toward the cap 45. The positive electrode terminal plate 70 is electrically connected to a positive electrode terminal 71 that protrudes from one side surface in the longitudinal direction X of the case 10. When a malfunction occurs in the battery 30, the gas exhausted from the battery safety valve 37 is exhausted to the outside of the battery block 20 through the opening 64.

[0034] A vertical gap is formed between the positive electrode terminal plate 70 and the upper end of the inner surface of the case 10 to form a gas exhaust path, so that the gas exhausted to the outside of the battery block 20 is exhausted to the outside of the case 10 through the exhaust hole 13.

[0035] The holding portion 65 of the lower holder 62 is a circular hole formed on the upper surface of the lower holder 62. The lower end of the battery 30 is held by being fitted into the holding portion 65. The opening 66 is formed at the center of the holding portion 65 so as to penetrate the lower holder 62 in the vertical direction. The opening 66 is, for example, a hole with a circular cross-section. The lower end surface of the casing body of the battery 30, which will be described later, is exposed within the opening 66. The negative electrode terminal plate 80 and the lower end surface of the battery 30 are electrically connected via a negative electrode lead portion (not shown). The negative electrode lead portion may be a connecting lead portion formed integrally with the negative electrode terminal plate 80 and extending toward the lower end surface of the battery 30. The negative electrode terminal plate 80 is electrically connected to a negative electrode terminal 72 that protrudes from one side surface in the longitudinal direction X of the case 10.

[0036] The battery 30 will be described with reference to Figure 5. The battery 30 is a cylindrical battery and is a lithium-ion battery. The battery 30 is not limited to a cylindrical battery, but may also be a prismatic battery, a laminated battery, etc. The battery 30 is not limited to a non-aqueous battery, but may also be an aqueous battery.

[0037] The battery 30 comprises an electrode body 34, an electrolyte (not shown), and an outer casing 35 that houses the electrode body 34 and the electrolyte. The electrolyte is ionic conductive (for example, lithium ion conductive). The electrolyte includes, for example, a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The electrolyte is not limited to a liquid electrolyte and may be a solid electrolyte using a gel-like polymer or the like. The electrode body 34 has a positive electrode 31, a negative electrode 32, and a separator 33, and has a wound structure in which the positive electrode 31 and the negative electrode 32 are wound in a spiral shape via the separator 33. The outer casing 35 has a bottomed cylindrical shape with an open top, and the opening of the outer casing 35 is closed by a sealing body 36.

[0038] The battery 30 includes insulating plates 38a and 38b positioned above and below the electrode body 34, respectively. In the example shown in Figure 3, a positive electrode lead 39 attached to the positive electrode 31 extends towards the sealing body 36 through a through hole in insulating plate 38a, and a negative electrode lead 40 attached to the negative electrode 32 extends towards the bottom of the outer casing 35 through a through hole in insulating plate 38b. The positive electrode lead 39 is connected to the lower surface of the internal terminal plate 41, which is the bottom plate of the sealing body 36, by welding or the like. A cap 45, which is the top plate of the sealing body 36 and serves as the positive electrode external terminal, is electrically connected to the internal terminal plate 41. The negative electrode lead 40 is connected to the inner surface of the bottom of the outer casing 35 by welding or the like, so that the bottom of the outer casing 35 becomes the negative electrode external terminal.

[0039] The sealing body 36 has a structure in which an internal terminal plate 41, a first valve body 42, an insulating member 43, a second valve body 44, and a cap 45 are stacked in order from the electrode body 34 side. Each component constituting the sealing body 36 is, for example, disc-shaped or ring-shaped, and each component except the insulating member 43 is electrically connected to one another. The first valve body 42 and the second valve body 44 are connected to each other at their respective centers, with the insulating member 43 interposed between their respective peripheral edges.

[0040] In this embodiment, the battery safety valve 37 of the sealing body 36 is composed of a first valve body 42, a second valve body 44, and a cap 45. When an abnormality occurs in the battery 30 and the internal pressure rises to a predetermined value, the first valve body 42 deforms and breaks, pushing the second valve body 44 upward toward the cap 45, thereby interrupting the current path between the first valve body 42 and the second valve body 44. If the internal pressure rises further and reaches a predetermined value, the second valve body 44 breaks, and gas is exhausted from the battery exhaust hole 45a formed on the side surface of the protrusion of the cap 45.

[0041] The placement of the battery safety valve 37 is not limited to this embodiment. The battery safety valve may be provided at the bottom of the outer casing 35, which is below the battery 30, and may be configured to release gas from the battery safety valve when the internal pressure of the battery rises. In that case, a gas exhaust path is formed between the lower end of the battery 30 and the lower end of the inner surface of the case 10 so that the gas released from the bottom of the outer casing 35 is exhausted to the outside of the case 10 through the exhaust hole 13 of the case 10.

[0042] As shown in FIG. 4, the space between the holding portion 63 of the upper holder 61 and the holding portion 65 of the lower holder 62 and surrounding each battery 30 communicates with the outer space of the battery holder 60 within the case 10. As a result, coolant 50 exists in the space surrounding each battery 30, similar to the outer space of the battery holder within the case 10. The coolant 50 preferably exists within the case 10 up to above the upper end of each battery 30. In this case, the gas exhausted from the battery safety valve 37 is sent to the exhaust hole 13 while contacting the coolant 50, making it easier to lower the temperature of the gas exhausted from the exhaust hole 13 to the outside.

[0043] As described above, in the battery pack 1 of the present embodiment, within the case 10, a pocket portion 93 having an opening P at its upper end is provided at a portion covering the exhaust hole 13.

[0044] The pocket portion 93 is provided at an intermediate portion in the width direction Y on the inner surface of the first side wall 91a of the main body member 91. The lower end of the pocket portion 93 is located near this lower end, below the lower end of the exhaust hole 13, on the inner surface of the first side wall 91a. The internal space of the pocket portion 93 faces the exhaust hole 13. The upper end of the opening P of the pocket portion 93 is provided at a position higher than the upper end of the battery of the battery block 20.

[0045] As shown in FIG. 6, when the pack safety valve 82 is opened, a part of the coolant 50 within the case 10 is discharged to the outside of the case 10 through the exhaust hole 13 together with the gas exhausted from the battery. At this time, the coolant 50 in at least the portion of the internal space of the pocket portion 93 higher than the lower end of the exhaust hole 13 is discharged to the outside of the case 10. In this case, the coolant flowing from within the case 10 toward the exhaust hole 13 can be blocked by the wall portion of the pocket portion 93. As a result, the height of the coolant 50 existing in the arrangement space of the battery block 20 within the case 10 can be set as the height near the upper end of the pocket portion 93, suppressing a significant decrease in the height of the coolant 50. Therefore, in a configuration where the pack safety valve 82 is provided on the lateral side surface of the case 10, the outflow of the coolant 50 when the pack safety valve 82 is opened can be suppressed. Thus, the spread of thermal runaway between the plurality of batteries can be suppressed.

[0046] Further, the upper end of the pack safety valve 82 is disposed at a position lower than the uppermost end of the case 10. Thereby, the height of the battery pack 1d does not depend on the pack safety valve 82. Also, a plurality of battery packs 1 can be provided and stacked in the vertical direction. Further, since the pack safety valve 82 is provided on one side surface in the longitudinal direction X which is the side surface on the terminal protruding side in the lateral direction of the case 10, a space that does not interfere with each terminal 71, 72 and each port 73, 74 can be effectively utilized outside one side surface in the longitudinal direction X. Thereby, the space outside the case 10 can be effectively utilized.

[0047] Further, the exhaust hole 13 is provided below the upper end of the battery, and the upper end of the opening P of the pocket portion 93 is provided at a position higher than the upper end of the battery. Thereby, as shown in FIG. 6, when the pack safety valve 82 is opened, each battery can be continuously immersed sufficiently in the coolant 50. Thereby, the decrease in the cooling performance of each battery can be suppressed, and the spread of thermal runaway between a plurality of batteries can be further suppressed.

[0048] Further, in this example, the pocket portion 93 is integrally formed of the same material as the main body member 91 of the case 10. Thereby, the assembly work of the case 10 can be facilitated. Further, in this example, each of the opening area of the opening P of the pocket portion 93, the cross-sectional area orthogonal to the vertical direction Z of the internal space of the pocket portion, and the area of the exhaust hole 13 is larger than the total area of the exhaust holes 45a (see FIG. 5) of the battery safety valve in each of the plurality of batteries. Thereby, it is possible to suppress that the strength of the wall portions of the case 10 and the pocket portion 93 is insufficient with respect to the pressure received from the gas exhausted from the battery when the battery safety valve is opened, and it is possible to suppress damage to the case 10 and the pocket portion 93.

[0049] FIG. 7 is a view corresponding to FIG. 3 in the battery pack 1e of the comparative example. FIG. 8 is a view corresponding to FIG. 7 at the time of opening of the pack safety valve 82 in the comparative example.

[0050] In the comparative example, as shown in Figures 1 to 6, no pocket is provided inside the case 10e. In this comparative example, as shown in Figure 7, when the pack safety valve 82 is opened, a portion of the coolant 50 inside the case 10e is discharged outside the case 10e through the exhaust hole 13 along with the gas exhausted from the batteries in the battery block 20. At this time, since no pocket is provided inside the case 10e, the coolant 50 flowing from inside the case 10e towards the exhaust hole 13 is not blocked, and the height of the coolant 50 in the space where the battery block 20 is located is below the lower end of the exhaust hole 13. As a result, the batteries in the battery block 20 are not sufficiently cooled by the coolant 50, and there is a possibility that thermal runaway will spread among the multiple batteries in the battery block 20. The embodiment shown in Figures 1 to 6 can prevent such problems.

[0051] Figure 9 is an enlarged view corresponding to the end on the pack safety valve 82 side of Figure 3 in a battery pack 1f of another embodiment. In this example, the lower end of the pocket portion 94 reaches the bottom plate portion 91d of the case 10f. Specifically, the pocket portion 94 is formed by including the middle portion in the width direction of one end in the longitudinal direction X of the bottom plate portion 91d (the left end in Figure 9) and a wall portion 94a with a substantially U-shaped cross-section that rises from the upper surface of the upper end in the longitudinal direction of the bottom plate portion 91d. As a result, the exhaust hole 13 can be formed at a lower position in the vertical direction as long as it faces the internal space of the pocket portion 94, and even in that case, the outflow of coolant 50 when the pack safety valve 82 is opened can be suppressed. In this example, the other configurations and operations are the same as those in Figures 1 to 6.

[0052] Figure 10 is an enlarged view corresponding to the end of the pack safety valve 82 side in Figure 3, in a battery pack 1g of another embodiment. In this example, on one end face in the longitudinal direction X of the case 10g (the left end face in Figure 10), a roughly rectangular parallelepiped projection 92 is formed in the portion extending from the upper end of the middle part in the width direction to the middle part in the vertical direction. In addition, an exhaust hole 13 is formed in the wall portion 92a on the lateral outer side of the projection 92, so as to penetrate the wall portion 92a in the longitudinal direction X.

[0053] Furthermore, a pack safety valve 82 is provided on the outside of the wall portion 92a, in a position that covers the exhaust hole 13. On one end face in the longitudinal direction X of the lid 15 (the left end face in Figure 10), in the middle of the width direction, a lid-side projection 16 is formed that protrudes in the longitudinal direction X. The lid-side projection 16 closes the upper end opening of the projection 92. As a result, a pack safety valve 82 is provided on the outside of the lateral side surface of the case 10g. Also, on the inside of the case 10g, in the portion that covers the exhaust hole 13, a roughly rectangular parallelepiped cylindrical pocket portion 95 is provided, having an opening P at the upper end and a closed lower end. In this example, the other configurations and operations are the same as those in Figures 1 to 6.

[0054] Furthermore, in the configurations of the examples shown in Figures 1 to 6, or Figure 9, or Figure 10, the pocket portion may be provided on the inside of the wall at one end in the longitudinal direction of the case, covering substantially the entire width. Also, in the configurations of the examples shown in Figures 1 to 6, or Figure 9, or Figure 10, each terminal and each port may protrude from one side in the width direction of the case body, an exhaust hole may be formed in the side wall located at one end in the width direction of the case, a pack safety valve may be provided on the outside of this side wall, and the pocket portion may be provided on the inner surface of this side wall so as to cover the exhaust hole.

[0055] Figure 11 is an enlarged perspective view of the exhaust port 13 side end of a battery pack 1h of another embodiment with the cover removed. Figure 12 is an enlarged perspective view showing the D-D cross-section of Figure 11. In the configurations shown in Figures 1 to 6 above, the pocket portion is formed by the case alone. On the other hand, in this example, the pocket portion 96 is composed of a part of the case 10e and a part of the battery holder 60a, and a part of the battery holder 60a forms the main body wall 96a, which is the wall of the pocket portion 96. Specifically, a battery holder 60a constituting a battery block is arranged inside the case 10e. A wall portion 97 with a substantially flat outer surface is provided at one end of the battery holder 60a in the longitudinal direction X (the left end in Figures 11 and 12). In Figures 11 and 12, the battery holder 60a is shown as a rectangular parallelepiped, but in reality, as shown in Figure 4, it is configured in a shape that allows multiple batteries to be held inside and immersed in a cooling liquid.

[0056] In this example, unlike the configurations shown in Figures 1 to 6, the case 10e does not have an integrally molded pocket. The main body member 91 of the case 10e is simply a box-shaped, roughly rectangular parallelepiped with an open top. An exhaust hole 13 is formed in the middle of the width direction Y and the vertical direction Z of the first side wall 91a at one end in the longitudinal direction of the case 10e, penetrating the main body member 91 in the longitudinal direction X.

[0057] Inside the case 10e, a roughly rectangular, cylindrical pocket portion 96 is formed in the portion covering the exhaust hole 13, with an opening P at its upper end and a closed lower end.

[0058] The pocket portion 96 is composed of a part of the battery holder 60a and a part of the case 10e. The battery holder 60a includes a main body wall 96a located at one end in the thickness direction (longitudinal direction X), which is the protruding end of the pocket portion 96, and a substantially U-shaped space-forming wall 96b that protrudes from the side surface of the main body wall 96a and forms the internal space of the pocket portion 96. The pocket portion 96 is formed when the end face of the space-forming wall 96b is pressed against the portion surrounding the exhaust hole 13 on the inner surface of the first side wall 91a of the case 10e. As a result, the pocket portion 96 is formed in the middle of the width direction Y of the first side wall 91a of the case 10e, including the portion surrounding the exhaust hole 13. An opening P is formed at the upper end of the pocket portion 96.

[0059] Furthermore, the battery holder 60a can also be configured such that an elastic member, such as a cushioning material, is provided between the end of the battery holder 60a opposite to the longitudinal direction X of the case 10e and the inner surface of the case 10e. With this configuration, the end face of the space-forming wall 96b is pressed firmly against the inner surface of the first side wall 91a of the case 10e, making it easier to prevent the coolant from entering the pocket portion 96 from the outside to the inside through the space-forming wall 96b and the case 10e.

[0060] In this example, the pocket portion 96 is formed including a part of the battery holder 60a and a part of the case 10e, and a part of the battery holder 60a forms the main wall 96a of the pocket portion 96. As a result, there is no need to form the wall of the battery holder 60a adjacent to the main wall 96a of the pocket portion 96 in the lateral direction, so that the length of the longitudinal X of the battery block 20 arrangement space for arranging batteries within the case 10e does not decrease. Therefore, the reduction in the battery block arrangement space within the case 10e is suppressed. Consequently, a decrease in volumetric energy density can be suppressed regardless of the formation of the pocket portion 96. In this example, the other configurations and operations are the same as those in Figures 1 to 6.

[0061] Figure 13 is an enlarged perspective view of the end of the exhaust port 13 side in a battery pack 1i of another embodiment with the cover removed. Figure 14 is an enlarged perspective view showing the E-E cross-section in Figure 13.

[0062] In this example, inside the case 10e, a roughly rectangular, cylindrical pocket portion 98 is formed in the portion covering the exhaust hole 13, with an opening P at its upper end and a closed lower end.

[0063] The battery holder 60b includes a main body wall 98a located at one end of the pocket portion 98 in the thickness direction, and two columnar space-forming walls 98b with a rectangular cross-section that extend vertically and protrude from the side surface of the main body wall 98a at two positions separated in the width direction Y perpendicular to the thickness direction of the pocket portion 98. The pocket portion 98 is formed when the end faces of the two space-forming walls 98b are pressed against the portion surrounding the exhaust hole 13 on the inner surface of the first side wall 91a of the case 10e. An opening P is formed at the upper end of the pocket portion 98.

[0064] According to the configuration of this example, the vertical height of the internal space of the pocket portion 98 can be increased. Furthermore, the exhaust hole 13 can be formed at a lower position in the vertical direction, as long as it faces the internal space of the pocket portion 98, and even in that case, the outflow of coolant when the pack safety valve 82 (see Figures 1 and 3) is opened can be suppressed. In this example, the other configurations and operations are the same as those in Figures 1 to 6, or Figures 11 and 12.

[0065] Figure 15 is an enlarged perspective view of the end of the exhaust port 13 side in a battery pack 1j of another embodiment, with the cover removed. Figure 16 is an enlarged perspective view showing the F-F cross-section in Figure 15.

[0066] In this example, a pocket portion 99 is formed inside the case 10e, covering the exhaust hole 13, with a shape similar to that shown in Figures 11 and 12.

[0067] In this example, the battery holder 60 has a main body wall 99a located at one end in the thickness direction of the pocket portion 99. On the other hand, unlike the configurations shown in Figures 11 and 12, no space-forming wall protruding from the main body wall 99a is formed in this example. In this example, the pocket portion 99 is formed by sandwiching a U-shaped component 100, which forms the space-forming wall 99b of the pocket portion 99, between the lateral side surface of the main body wall 99a of the battery holder 60 and the inner surface of the case 10e. The U-shaped component 100 is made of, for example, resin or metal, and for example, the cross-section perpendicular to the longitudinal direction of the U-shaped component 100 is rectangular.

[0068] In this example, no space-forming walls are directly formed on either the battery holder 60 or the case 10e. This simplifies the shapes of the battery holder 60 and the case 10e, thereby facilitating their manufacture. In this example, the other configurations and operations are the same as those in Figures 1 to 6, or Figures 11 and 12.

[0069] In this example, the U-shaped component 100 may be formed from a cushioning material or an elastic material such as rubber. If the U-shaped component 100 is formed from a cushioning material, the cushioning material should be configured not to allow coolant to pass through. Alternatively, a flat cushioning material or an elastic material such as rubber may be interposed between the U-shaped component 100 and the side surface of the main body wall 99a of the battery holder 60. Furthermore, a flat cushioning material or an elastic material such as rubber, with an opening formed in the longitudinal direction X in the portion facing the exhaust hole 13, may be interposed between the inner surface of the case 10e and the U-shaped component 100.

[0070] Figure 17 is an enlarged perspective view of the end of the exhaust port 13 side in a battery pack 1k of another embodiment, with the cover removed. Figure 18 is an enlarged perspective view showing the G-G cross-section in Figure 17.

[0071] In this example, a pocket portion 101 with the same shape as the configuration shown in Figures 11 and 12 is formed inside the case 10h, covering the exhaust hole 13. In this example as well, similar to the configuration shown in Figures 15 and 16, no space-forming wall is formed that protrudes from the main body wall 101a of the battery holder 60. In this example, a roughly rectangular recessed portion 103 that is recessed outward is formed on the inner surface of the first side wall 102a that constitutes the main body member 102 of the case 10h. The upper end of the recessed portion 103 reaches the upper end of the first side wall 102a.

[0072] On the inner surface of the first side wall 102a, the substantially U-shaped peripheral edge of the recess 103 is pressed against the lateral side surface of the main body wall 101a, thereby forming the pocket portion 101. In this example, the side wall portion of the recess 103 corresponds to the space-forming wall. In this example, the shape of the battery holder 60 can be simplified, thus facilitating the manufacture of the battery holder 60. In this example, the other configurations and operations are the same as those in Figures 1 to 6, or in Figures 11 and 12.

[0073] In addition, in the configurations of the examples shown in Figures 11 to 18 above, the pocket portion may be provided on the inside of the first side wall of the case, covering approximately the entire width Y direction. Furthermore, in the configurations of the examples shown in Figures 11 to 18, each terminal and each port may protrude from one side surface in the width Y direction of the case, an exhaust hole may be formed in the side wall located at one end in the width Y direction of the case, a pack safety valve may be provided on the outside of this side wall, and the pocket portion may be provided on the inside of this side wall so as to cover the exhaust hole.

[0074] In the configurations of the examples above, multiple battery blocks can be housed inside the case, and these battery blocks can be electrically connected to each other in series, parallel, or a combination of series and parallel. Furthermore, multiple battery packs of the examples above can be arranged side-by-side and housed in a larger case, with these battery packs electrically connected to each other in series, parallel, or a combination of series and parallel.

[0075] 1, 1e, 1f, 1g, 1h, 1i, 1j, 1k Battery pack, 10, 10e, 10f, 10g, 10h Case, 13 Exhaust vent, 15 Cover, 17 Exhaust vent, 20 Battery block, 30 Battery, 31 Positive electrode, 32 Negative electrode, 33 Separator, 34 Electrode body, 35 Outer casing, 36 Sealing body, 37 Battery safety valve, 38a, 38b Insulating plate, 39 Positive electrode lead, 40 Negative electrode lead, 41 Internal terminal plate, 42 First valve body, 43 Insulating member, 44 Second valve body, 45 Cap (Positive electrode external terminal), 45a Exhaust vent, 50 Coolant, 60, 60a, 60b Battery holder, 61 Upper holder, 62 Lower holder, 63 Holding part, 64 Opening, 65 Holding part, 66 Opening, 70 Positive terminal plate, 71 Positive terminal, 72 Negative terminal, 80 Negative terminal plate, 82 Pack safety valve, 84 Pocket section, 91 Main body member, 92 Protruding section, 93, 94, 95, 96 Pocket section, 97 Wall section, 98, 99 Pocket section, 100 U-shaped component, 101 Pocket section, 102 Main body member, 103 Recessed section.

Claims

1. A battery pack in which a plurality of batteries are housed in a case, wherein each plurality of batteries has a battery safety valve that opens when the internal pressure rises and exhausts the internal gas, and is immersed in a coolant while being held in a battery holder within the case, the case has exhaust holes on its lateral sides, and a pack safety valve is provided on the outside of the lateral sides of the case that opens when the internal pressure rises and exhausts the gas from the exhaust holes, and on the inside of the case, a cylindrical pocket portion is provided in the portion covering the exhaust holes, having an opening at the upper end and a closed lower end, the pocket portion is formed by including a part of the battery holder and a part of the case, and the part of the battery holder forms the wall of the pocket portion.

2. The battery holder includes a main body wall located at one end in the thickness direction of the pocket portion, and a space-forming wall protruding from the side surface of the main body wall and forming the internal space of the pocket portion, wherein the pocket portion is formed when the end face of the space-forming wall is pressed against the inner surface of the case, as described in claim 1.

3. The battery holder includes a main body wall located at one end in the thickness direction of the pocket portion, and space-forming walls provided at two positions on the side surface of the main body wall that are separated in a direction perpendicular to the thickness direction of the pocket portion and extend in the vertical direction, wherein the pocket portion is formed when the end faces of the two space-forming walls are pressed against the inner surface of the case.

4. The battery pack according to claim 1, wherein the pocket portion is formed by sandwiching a U-shaped component that forms a space-forming wall for the pocket between the lateral side surface of the battery holder and the inner surface of the case.

5. The battery pack according to claim 1, wherein a recessed portion is formed on the inner surface of the wall portion at the lateral end of the case, and the pocket portion is formed when the peripheral edge of the recessed portion is pressed against the lateral side surface of the battery holder on the inner surface of the wall portion.

Images