Electricity storage device

Abstract

A power storage device includes a power storage element, an exterior body that accommodates the power storage element, an exhaust pipe, and a film member. The exhaust pipe connects the inside of the exterior body and the outside of the exterior body and forms a part of the gas flow path. The membrane member blocks a gas flow path at the tip of the exhaust pipe near the outside, and has air permeability.

Description

Technical Field

[0001] The present invention relates to an electric storage device. Background Art

[0002] Patent document 1 discloses a battery module, which has in a housing: a plurality of secondary batteries, each of which has an exhaust valve for releasing high-temperature gas in an abnormal situation; and an exhaust path for exhausting the high-temperature gas to the outside. In this battery module, the exhaust valves of the secondary batteries are connected to the exhaust path and the connection port in an independent connection path. A connection plate is provided in the exhaust path for connecting several terminals of one side of the secondary battery in parallel using an external lead. The connection plate covers the connection port through an external lead and a gas rectifying part, and the gas rectifying part becomes a rectifying plate that guides the high-temperature gas in one direction due to deformation when the high-temperature gas is discharged.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-037873 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the above-mentioned conventional battery module, when the secondary battery releases gas in an abnormal situation, the gas rectifying part is bent due to the gas released from the abnormal battery, thereby forming a rectifying plate, and the gas passing through the connection path flows into the exhaust path while being guided in one direction by the rectifying plate. In this way, by configuring a component for blocking the flow path of the gas and releasing it (opening and closing the flow path of the gas) in a part of the flow path of the gas discharged from the storage element such as the secondary battery, the flow path of the gas can be ensured, and the invasion of foreign matter into the interior of the outer casing that accommodates the storage element can be suppressed. However, in the storage device in which a component for opening and closing the flow path of the gas is provided inside the outer casing as in the above-mentioned conventional battery module, there is a problem that the configuration operation of the component is easy to become difficult, or the inspection of the component after completion is difficult. Such a situation has become the main reason for hindering the improvement of the reliability of the storage device.

[0008] The present invention was completed by the inventors of the present application with new attention paid to the above-mentioned problems, and an object of the present invention is to provide a power storage device capable of easily improving reliability.

[0009] Solutions to Solve Problems

[0010] An energy storage device according to one embodiment of the present invention comprises: an energy storage element; an outer casing that accommodates the energy storage element; an exhaust pipe that connects the interior of the outer casing with the exterior of the outer casing to form a part of a gas flow path; and a membrane member that blocks the gas flow path at a front end portion of the exhaust pipe close to the exterior and has air permeability.

[0011] Effects of the Invention

[0012] According to the present invention, it is possible to provide a power storage device capable of easily improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a perspective view showing the appearance of the power storage device according to the embodiment.

[0014] Figure 2 It is an exploded perspective view of the power storage device according to the embodiment.

[0015] Figure 3 It is a perspective view showing the structure of the power storage element according to the embodiment.

[0016] Figure 4 It is a perspective view showing the appearance of an exhaust pipe according to the embodiment.

[0017] Figure 5 It is a cross-sectional view showing the structure of an exhaust pipe and its surroundings according to the embodiment.

[0018] Figure 6 It is a cross-sectional view showing a cross section of a normal membrane member.

[0019] Figure 7 It is a cross-sectional view showing a film member whose shape changes as the internal pressure of the exterior body increases.

[0020] Figure 8 It is a cross-sectional view showing a film member partially peeled off due to a rise in the internal pressure of the exterior body.

[0021] Fig. 9 It is a cross-sectional view showing a front end portion of an exhaust pipe according to Modification 1 of the embodiment.

[0022] Fig.10 It is a cross-sectional view showing a front end portion of an exhaust pipe according to Modification 2 of the embodiment.

[0023] Fig.11 It is a cross-sectional view showing a front end portion of an exhaust pipe according to Modification 3 of the embodiment.

[0024] Fig.12 It is a cross-sectional view showing a front end portion of an exhaust pipe according to Modification 4 of the embodiment. DETAILED DESCRIPTION

[0025] (1) An electric storage device according to one embodiment of the present invention comprises: an electric storage element; an outer casing that accommodates the electric storage element; an exhaust pipe that connects the interior of the outer casing with the exterior of the outer casing and forms a part of a gas flow path; and a membrane member that blocks the gas flow path at a front end portion of the exhaust pipe close to the exterior and has air permeability.

[0026] According to the storage element involved in one embodiment of the present invention, under normal circumstances, the front end of the exhaust pipe is blocked by the membrane member, thereby suppressing the intrusion of foreign matter such as water into the interior of the outer body. The membrane member has air permeability, so it can allow ventilation for pressure balance between the outside of the outer body and the inside of the outer body under normal circumstances. The membrane member having the above-mentioned function is arranged at the front end of the exhaust pipe, so it is easy to arrange the membrane member to the exhaust pipe, or to inspect it based on visual observation from the outside. Therefore, according to the storage device involved in one embodiment of the present invention, it is easy to improve reliability.

[0027] (2) Based on the power storage device described in (1) above, the membrane member may include a first membrane member that overlaps in the direction of the flow path of the gas and has air permeability, and a second membrane member that overlaps in the direction of the flow path of the gas and has air permeability, the second membrane member being arranged in the flow path of the gas at a position closer to the outside than the first membrane member, and the air permeability of the second membrane member is lower than that of the first membrane member.

[0028] According to the power storage device described in (2) above, the membrane member has at least two layers (a first membrane member and a second membrane member), so that the mechanical strength against foreign matter or pressure from the outside can be easily improved. Therefore, the membrane member exposed to the outside space or arranged at a position close to the outside space can be more reliably protected. As a result, the reliability of the power storage device relative to the outside space of the power storage device can be more reliably improved.

[0029] (3) In the power storage device described in (2) above, the first film member may have a higher tensile strength than the second film member, and the second film member may have a lower liquid permeability than the first film member.

[0030] According to the power storage device described in (3) above, the first membrane member can improve the mechanical strength of the membrane member as a whole, and the second membrane member can improve the resistance of the membrane member to liquid. Therefore, the membrane member maintains a good state. As a result, the reliability of the power storage device relative to the internal space and the external space of the power storage device can be more reliably improved.

[0031] (4) In the power storage device described in any one of (1) to (3) above, the membrane member may be bonded to an outer surface of the front end portion of the exhaust pipe, the outer surface being an outer surface close to the outside in the flow path of the gas.

[0032] According to the power storage device described in (4) above, the membrane member is bonded to the outer surface of the exhaust pipe in the gas flow path close to the outside, thereby suppressing the membrane member from being peeled off or falling off from the exhaust pipe due to an increase in the external pressure of the outer body or collision of foreign matter such as water with the membrane member.

[0033] (5) In the power storage device described in any one of (1) to (4) above, the film member may be inclined with respect to the extending direction of the exhaust pipe.

[0034] According to the power storage device described in (5) above, the membrane member is arranged obliquely with respect to the extension direction of the exhaust pipe, that is, the direction of the flow path of the gas inside the exhaust pipe. Therefore, the area of ​​the membrane member that can be ventilated becomes larger. As a result, the pressure balance between the outside of the outer body and the inside of the outer body is more smoothly performed.

[0035] (6) In the power storage device described in any one of (1) to (5) above, the exhaust pipe may include a flange portion provided at the front end portion, the flange portion protruding outward in a radial direction of the exhaust pipe, and the film member may be joined to the flange portion.

[0036] According to the power storage device described in (6) above, even when the outer diameter of the exhaust pipe is small, the bonding area between the film member and the front end portion of the exhaust pipe can be ensured.

[0037] (7) In the power storage device described in any one of (1) to (6) above, the exhaust pipe may include an end wall portion disposed at the front end portion, the end wall portion having a through hole formed therein for allowing the gas to pass therethrough, and the membrane member may be joined to the end wall portion in a state in which the through hole is blocked.

[0038] According to the power storage device described in (7) above, even when the outer diameter of the exhaust pipe is large, the membrane member only needs to be large enough to block the through hole in the end wall portion. Therefore, there is no need to prepare a membrane member large enough to match the outer diameter of the exhaust pipe.

[0039] (8) In the power storage device described in any one of (1) to (7), the exhaust pipe may include a protruding portion disposed at the front end portion, the protruding portion protruding toward the outside relative to an outer surface of the membrane member closer to the outside.

[0040] According to the power storage device described in (8) above, the membrane member is more reliably protected by having the protruding portion that protrudes outward (toward the outside of the outer casing) relative to the membrane member. That is, the function of the membrane member is more reliably maintained.

[0041] Hereinafter, the power storage device involved in the embodiments of the present invention (including its modified examples) will be described with reference to the accompanying drawings. The embodiments described below all represent general or specific examples. The numerical values, shapes, materials, components, configuration positions and connection methods of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. In each figure, dimensions, etc. are not strictly illustrated. In each figure, the same or identical components are marked with the same figure mark.

[0042] In the following description and drawings, the arrangement direction of multiple energy storage elements or the opposing direction of the long side of the container of the energy storage element is defined as the X-axis direction. The arrangement direction of a pair of (positive and negative) terminals in a energy storage element or the opposing direction of the short side of the container of the energy storage element is defined as the Y-axis direction. The arrangement direction of the main body and the cover of the outer body of the energy storage device or the arrangement direction of the main body and the cover of the container of the energy storage element is defined as the Z-axis direction. The above-mentioned X-axis direction, Y-axis direction and Z-axis direction are directions that intersect each other (orthogonal in this embodiment). Depending on the usage, the situation where the Z-axis direction is not the up-down direction is also considered, but for the convenience of explanation below, the Z-axis direction is set as the up-down direction for explanation.

[0043] In the following description, the positive direction of the X-axis indicates the direction of the arrow of the X-axis, and the negative direction of the X-axis indicates the direction opposite to the positive direction of the X-axis. When it is only referred to as the X-axis direction, it means both the positive direction of the X-axis and the negative direction of the X-axis or any one of the two directions. The same is true for the Y-axis direction and the Z-axis direction. Expressions such as parallel and orthogonal that indicate relative directions or postures strictly include situations where they are not the directions or postures. The so-called parallelism of two directions not only means that the two directions are completely parallel, but also means that they are substantially parallel, that is, including a difference of about a few percent. In the following description, when it is expressed as "insulated", it means "electrically insulated".

[0044] (Implementation Method)

[0045] [1. Overall description of the power storage device]

[0046] Figure 1 It is a perspective view showing the appearance of the power storage device 10 according to the embodiment. Figure 2 It is an exploded perspective view of the power storage device 10 according to the embodiment.

[0047] The power storage device 10 is a device that can charge electricity from the outside and discharge electricity to the outside. In the present embodiment, it has a roughly rectangular parallelepiped shape. The power storage device 10 is a battery module (battery pack) used for power storage purposes or power supply purposes. Specifically, the power storage device 10 is used as a battery for driving or starting the engine of a mobile body such as a car, a motor two-wheeled vehicle, a water vehicle, a ship, a snowmobile, an agricultural machine, a construction machine, or a railway vehicle for an electric railway. As the above-mentioned car, an electric car (EV), a hybrid electric car (HEV), a plug-in hybrid electric car (PHEV), and a fossil fuel (gasoline, light oil, liquefied natural gas, etc.) car are exemplified. As the above-mentioned railway vehicle for the electric railway, a tram, a monorail, a linear engine traction train (linear motor car), and a hybrid electric car with both a diesel engine and an electric motor are exemplified. The power storage device 10 can also be used as a fixed battery for home use or business use.

[0048] like Figure 1 As shown, the power storage device 10 includes an exterior body 100. Figure 2 As shown, a plurality of power storage elements 200, a bus bar holder 300, and a bus bar 400 are housed inside the outer casing 100. In addition to the above-mentioned components, the power storage device 10 may further include: spacers or unit holders respectively arranged along the plurality of power storage elements 200, restraining members restraining the plurality of power storage elements 200, and a circuit board for monitoring or controlling the charge state and discharge state of the plurality of power storage elements 200.

[0049] The outer casing 100 is a box-shaped (roughly rectangular) container (module casing) constituting the casing (housing) of the power storage device 10. The outer casing 100 is arranged outside the plurality of power storage elements 200, the bus bar holder 300, and the bus bar 400, and protects the above-mentioned power storage elements 200 and the like. The outer casing 100 is formed of insulating members such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), tetrafluoroethylene-perfluoroalkylvinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or composite materials thereof, or metals with insulating coatings. The outer casing 100 thereby prevents the power storage elements 200 and the like from coming into contact with external metal members and the like. As long as the insulation of the power storage element 200 and the like is maintained, the exterior body 100 may be formed of a conductive member such as metal.

[0050] The outer body 100 includes an outer body main body 110 constituting the main body of the outer body 100, and a cover body 120 that blocks the opening of the outer body 100. The outer body main body 110 is a bottomed rectangular cylindrical shell (shell) formed with an opening, and accommodates the storage element 200 and the like. The cover body 120 is a flat rectangular member that blocks the opening of the outer body main body 110. The cover body 120 and the outer body main body 110 are joined to each other by adhesive, heat sealing (thermal welding), ultrasonic welding, laser welding, or screwing. As a result, the outer body 100 has a sealed (sealed) structure inside (except for the exhaust pipe 150 described later). The positive external terminal 121 and the negative external terminal 122 are provided on the cover body 120. The storage device 10 is charged with electricity from the outside through the positive external terminal 121 and the negative external terminal 122, and discharges electricity to the outside.

[0051] In this embodiment, the outer casing 100 has an exhaust pipe 150 disposed on the cover 120. The exhaust pipe 150 forms a gas flow path 250 (using the exhaust pipe 150) when the gas is exhausted from the power storage element 200. Figure 5 The exhaust pipe 150 is a part of the outer casing 100 described later. A membrane member 160 is arranged at the front end of the exhaust pipe 150, which has air permeability and blocks the gas flow path 250. When gas is discharged from the energy storage element 200, due to the rapid increase in the internal pressure of the outer casing 100, the membrane member 160 breaks and / or moves, so that the gas is guided to the outside of the outer casing 100 via the exhaust pipe 15. A pipe member such as a gas pipe not shown in the figure can be connected to the exhaust pipe 150. The gas discharged from the exhaust pipe 150 moves to a predetermined position via the pipe member. The structure of the exhaust pipe 150 and its surroundings will be described using Figure 4~Figure 8 To be described later.

[0052] The energy storage element 200 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 200 has a flat rectangular shape (square), and in the present embodiment, eight energy storage elements 200 are arranged side by side along the X-axis direction. The size and shape of the energy storage element 200 and the number of arranged energy storage elements 200 are not limited, and the energy storage element 200 may be a cylindrical shape (cylindrical shape), an oblong cylindrical shape, an elliptical cylindrical shape, or only one energy storage element 200 may be arranged. The energy storage element 200 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, and may be a capacitor. The energy storage element 200 may be a primary battery instead of a secondary battery. The energy storage element 200 may also be a battery using a solid electrolyte. The energy storage element 200 may also be a bag-type energy storage element. A detailed description of the structure of the energy storage element 200 will be described using Figure 3 To be described later.

[0053] The bus bar holder 300 is a flat and rectangular member (also referred to as a bus bar frame or a bus bar plate) that insulates the bus bar 400 from other members and restricts the position of the bus bar 400. The bus bar holder 300 is provided with a plurality of bus bar openings 317 that expose a portion of each of the plurality of bus bars 400 to the plurality of power storage elements 200.

[0054] At the center of the bus bar holder 300 in the Y-axis direction, along the gas discharge valves 231 (see Figure 3 ) are arranged in a manner that a path forming portion 319 extending in the X-axis direction and protruding in the positive direction of the Z-axis is provided. Through the path forming portion 319, an exhaust path for the gas exhausted from the storage element 200 is formed along the X-axis direction. At the end of the path forming portion 319 in the long side direction, as shown in FIG. Figure 2 As shown, a path outlet 318 is provided. The gas exhausted from the power storage element 200 preferentially passes through the path outlet 318 and is discharged to the outside of the outer casing 100 via the exhaust pipe 150. The bus bar holder 300 thus configured is fixed to the outer casing main body 110 of the outer casing 100 by a predetermined method such as bonding or thermal welding.

[0055] The bus bar 400 is a plate-shaped member connected to the storage element 200. The bus bar 400 is disposed above the plurality of storage elements 200 and is connected to the terminals 240 (see Figure 3 ) connection (joining). Specifically, the bus bar 400 connects the terminals 240 of the plurality of storage elements 200 to each other, and electrically connects the terminals 240 of the storage elements 200 at the ends to the positive external terminal 121 and the negative external terminal 122. The bus bar 400 is formed of a conductive member made of a metal such as aluminum, aluminum alloy, copper, copper alloy, nickel, or a combination thereof, or a conductive member other than a metal.

[0056] The busbar 400 includes a busbar 410, a busbar 420, and three busbars 430. The three busbars 430 connect two storage elements 200 in parallel to form four storage element groups, and connect the four storage element groups in series. The busbar 410 is connected to the positive terminals of the two storage elements 200 in the storage element group arranged at the end in the positive direction of the X-axis, and is electrically connected to the positive external terminal 121. The busbar 420 is connected to the negative terminals of the two storage elements 200 in the storage element group arranged at the end in the negative direction of the X-axis, and is electrically connected to the negative external terminal 122. The electrical connection method of the plurality of storage elements 200 is not particularly limited, and the plurality of storage elements 200 may be connected in series or / and in parallel by any combination.

[0057] [2. Description of energy storage elements]

[0058] Figure 3 2 is a perspective view showing the structure of the power storage element 200 according to the embodiment. Specifically, Figure 3 Will Figure 2 The appearance of one of the plurality of storage elements 200 is shown in an enlarged manner. It should be noted that all of the plurality of storage elements 200 have the same structure, so the structure of one storage element 200 will be described below.

[0059] like Figure 3 As shown, the storage element 200 includes a container 210, a pair of (positive and negative, the same below) terminals 240, and an upper gasket 242. In addition, a lower gasket, an electrode body, a pair of collectors, and an electrolyte (non-aqueous electrolyte) are housed inside the container 210, but their illustration is omitted. As for the electrolyte, there is no particular limitation on its type as long as it does not impair the performance of the storage element 200, and various electrolytes can be selected. In addition to the above-mentioned components, the storage element 200 may also have a spacer arranged on the side or below the electrode body and an insulating film that wraps the electrode body. In addition, an insulating film (shrink tube, etc.) covering the outer surface of the container 210 may be arranged around the container 210.

[0060] The container 210 is a rectangular parallelepiped (square or box-shaped) shell having a container body 220 with an opening and a cover plate 230 that blocks the opening of the container body 220. The container body 220 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 210, and has an opening formed in the positive direction of the Z axis. The container body 220 has a pair of long side surfaces on the sides of the X axis direction, a pair of short side surfaces on the sides of the Y axis direction, and a bottom surface in the negative direction of the Z axis. The cover plate 230 is a rectangular plate-shaped member that constitutes the cover of the container 210, and is arranged to extend along the Y axis direction in the positive direction of the Z axis of the container body 220. The cover plate 230 is provided with a gas discharge valve 231 that releases the pressure when the pressure inside the container 210 rises excessively, and a liquid injection portion (not shown) for injecting electrolyte into the container 210. After the electrode body and the like are housed inside the container body 220, the container body 220 and the cover plate 230 are joined by welding or the like, thereby forming a structure in which the interior is sealed. The material of the container 210 (the container body 220 and the cover plate 230) is not particularly limited, and a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel plate can be used, and a resin can also be used.

[0061] The terminal 240 is a terminal member (positive terminal and negative terminal) of the storage element 200 disposed on the cover plate 230, and is electrically connected to the positive electrode plate and the negative electrode plate of the electrode body via the current collector. The terminal 240 is a metal member for conducting electricity stored in the electrode body to the external space of the storage element 200 and conducting electricity to the internal space of the storage element 200 in order to store electricity in the electrode body. The terminal 240 is formed of aluminum, aluminum alloy, copper, copper alloy, etc.

[0062] The electrode body is a storage element (power generation element) formed by stacking a positive plate, a negative plate and a separator. The positive plate has a positive active material layer formed on a collector foil made of a metal such as aluminum or an aluminum alloy. The negative plate has a negative active material layer formed on a collector foil made of a metal such as copper or a copper alloy. As the active material used in the positive active material layer and the negative active material layer, known materials can be appropriately used as long as they can absorb and release lithium ions. The separator can use a microporous sheet or non-woven fabric made of resin. In this embodiment, the electrode plates (positive plates and negative plates) are stacked in the X-axis direction to form an electrode body. The electrode body can also be a winding type electrode body formed by winding the electrode plates (positive plates and negative plates), a stacked type (stacked type) electrode body formed by stacking a plurality of flat plate-shaped electrode plates, or an accordion-shaped electrode body formed by folding the electrode plates into an accordion shape.

[0063] The collector is a conductive member (positive collector and negative collector) electrically connected to the terminal 240 and the electrode body. The positive collector is formed of aluminum or an aluminum alloy, etc., similarly to the collector foil of the positive electrode plate, and the negative collector is formed of copper or a copper alloy, etc., similarly to the collector foil of the negative electrode plate. The upper gasket 242 is arranged between the cover plate 230 and the terminal 240, and is a gasket that insulates and seals the cover plate 230 and the terminal 240. The lower gasket is arranged between the cover plate 230 and the collector, and is a gasket that insulates and seals the cover plate 230 and the collector. The upper gasket 242 and the lower gasket can be formed of any raw material as long as they have insulating properties.

[0064] [3. Exhaust pipe and its surrounding structure]

[0065] In the power storage device 10 configured as described above, the outer casing 100 is composed of the cover 120 and the outer casing body 110, and the joint portion of the cover 120 and the outer casing body 110 is bonded or welded in such a manner that the interior of the outer casing 100 is sealed (sealed) as described above. Thus, the intrusion of foreign matter such as water from the joint portion between the cover 120 and the outer casing body 110 is suppressed. However, in this case, due to changes in the external environment (atmospheric pressure or air temperature) of the outer casing 100, the pressure difference (internal and external pressure difference) between the interior of the outer casing 100 and the exterior of the outer casing 100 is likely to increase. This becomes a major cause of damage or deterioration of the outer casing 100.

[0066] In this regard, in the power storage device 10 according to the present embodiment, the outer casing 100 has an exhaust pipe 150, and the exhaust pipe 150 is blocked by a permeable film member 160. The film member 160 suppresses the intrusion of foreign matter into the interior of the outer casing 100 through the exhaust pipe 150. In addition, since the film member 160 has permeability, air can move from one of the interior of the outer casing 100 and the exterior of the outer casing 100 to the other through the exhaust pipe 150. Thus, the pressure balance between the interior of the outer casing 100 and the exterior of the outer casing 100 is achieved in normal conditions.

[0067] When the gas discharge valve 231 is opened (opened) due to excessive increase in the internal pressure of the container 210 of the storage element 200, high-temperature and high-pressure gas is discharged from the gas discharge valve 231 to the inside of the outer casing 100. In this case, the temperature of other storage elements 200 may rise due to the high-temperature gas. In addition, the gas may leak from an unexpected position of the outer casing 100. Therefore, from the viewpoint of suppressing the spread of adverse effects when the gas discharge valve 231 of the storage element 200 is opened, it is important to quickly discharge the gas discharged from the storage element 200 from the exhaust pipe 150 to the outside of the outer casing 100.

[0068] In this regard, in the power storage device 10 involved in the present embodiment, when gas is exhausted from the power storage element 200, a gas flow path 250 is formed that connects the inside of the outer casing 100 with the outside of the outer casing 100. The exhaust pipe 150 forms a part of the gas flow path 250. When the internal pressure of the outer casing 100 increases sharply, the membrane member 160 installed on the exhaust pipe 150 breaks and / or moves to open the gas flow path 250. As a result, the gas inside the outer casing 100 is exhausted to the outside of the outer casing 100 via the exhaust pipe 150. In the following, Figure 4~Figure 8 The exhaust pipe 150 and its peripheral structure will be described in detail.

[0069] Figure 41 is a perspective view showing the appearance of an exhaust pipe 150 according to the embodiment. Figure 4 In FIG. 1 , the film member 160 is shown in a state separated from the exhaust pipe 150 , and a rough arrangement region of a joint portion 180 joining the film member 160 and the exhaust pipe 150 is shown as a ring-shaped region with a background. Figure 5 2 is a cross-sectional view showing the exhaust pipe 150 and its surrounding structure according to the embodiment. Figure 5 In the figure, we simply illustrate the Figure 1 A cross section of a portion of the power storage device 10 in the XZ plane parallel to the VV line. Figure 5 In FIG. 1 , the bus bar holder 300 and the bus bar 400 are omitted from illustration, and one of the plurality of power storage elements 200 is schematically shown. Figure 5 The arrangement of hollow arrows in denoted a gas flow path 250 when the gas is discharged from the power storage element 200 . Figure 5 The gas flow path 250 shown does not take into account the presence of the bus bar holder 300, but even when the bus bar holder 300 is provided, the gas flow path 250 flows from the power storage element 200 through the path outlet 318 of the path forming portion 319 (see Figure 2 ) and formed to the outside of the exhaust pipe 150.

[0070] Figure 6 1 is a cross-sectional view showing a cross section of the film member 160 in a normal state. Figure 7 1 is a cross-sectional view showing the film member 160 whose shape changes as the internal pressure of the exterior body 100 increases. Figure 8 This is a cross-sectional view showing the film member 160 partially peeled off due to the increase in the internal pressure of the exterior body 100 . Figure 6~Figure 8 The position of the section in Figure 5 The position of the section in is used as the reference.

[0071] like Figure 4 as well as Figure 5 As shown, the outer casing 100 has a cylindrical exhaust pipe 150. The space penetrating the exhaust pipe 150 in the axial direction of the exhaust pipe 150 (in the X-axis direction in this embodiment) is connected to the space inside the outer casing 100. Figure 5 As shown, the exhaust pipe 150 forms a part of a gas flow path 250 when the gas is exhausted from the energy storage element 200 .

[0072] In this embodiment, the exhaust pipe 150 is as follows Figure 5As shown, it is a component different from the cover body 120 of the outer body 100, but is treated as a part of the outer body 100. In other words, the "outside of the outer body 100" means the outside of the outer body 100 including the exhaust pipe 150. The method of joining the exhaust pipe 150 to the outer body 100 is not particularly limited. As the method of joining, bonding, welding, threading or pressing can be used. The exhaust pipe 150 can also be installed on the outer body 100 by rotating the exhaust pipe 150 having an external thread on the outer circumferential surface and joining it to a through hole provided in the outer body 100 and having an internal thread formed on the inner circumferential surface. In order to maintain or improve the airtightness of the joint portion between the exhaust pipe 150 and the outer body 100, a seal such as an O-ring can also be arranged at the joint portion.

[0073] The exhaust duct 150 is not necessarily a separate body from the exterior body 100. The exhaust duct 150 may be disposed on the exterior body 100 as a member integral with the exterior body 100. The cover body 120 integrally provided with the exhaust duct 150 may be manufactured by resin molding using a mold.

[0074] In the present embodiment, a film member 160 that blocks the flow path 250 of the gas is disposed at the front end portion 155 of the exhaust pipe 150 close to the outside of the outer body 100. The so-called "blocking the flow path 250 of the gas" is not limited to completely blocking (blocking) the flow of the gas. The film member 160 has a permeability to the extent that the pressure balance between the outside of the outer body 100 and the inside of the outer body 100 can be achieved in normal times. Therefore, in the case where gas is discharged from the storage element 200, the film member 160 may allow part of the gas to pass before breaking. However, the permeability of the film member 160 is not high enough to stop the increase in the internal pressure of the outer body 100 when the gas is discharged from the storage element 200. As a result, the flow path 250 of the gas when the gas is discharged from the storage element 200 becomes a state temporarily and substantially blocked by the film member 160. Therefore, it is described as "the film member 160 blocks the gas flow path 250 at the front end portion 155 of the exhaust pipe 150". It should be noted that the air permeability of the first film member 161 and the second film member 162 can be measured according to the "air permeability resistance" specified in JIS P8117: 2009. In other words, the smaller the air permeability resistance value, the higher the air permeability, and the larger the air permeability resistance value, the lower the air permeability.

[0075] The front end portion 155 of the exhaust pipe 150 is the portion at the farthest position from the outer casing 100 when the exhaust pipe 150 is divided into three equal parts in the pipe axis direction (X-axis direction). In other words, the front end portion 155 of the exhaust pipe 150 is a portion corresponding to the length L (refer to FIG. 1 ) of the exhaust pipe 150 from the end edge in the positive direction of the X-axis of the exhaust pipe 150. Figure 5 ) of 1 / 3.

[0076] More specifically, the exhaust pipe 150 according to the present embodiment includes an end wall portion 156 provided at a front end portion 155, and a through hole 158 is provided in the end wall portion 156 for allowing the gas inside the outer body 100 to pass therethrough. The membrane member 160 is joined to an outer surface (a surface on the downstream side in the gas flow path 250) 157 in the end wall portion 156. It should be noted that the surface on the downstream side in the gas flow path 250 may be a surface close to the outside of the outer body 100 or a surface facing the outside of the outer body 100. The membrane member 160 is joined to the outer surface 157 at a joint portion 180. The joint portion 180 is formed by heat welding, which uses a heated metal body to fuse the membrane member 160 and the exhaust pipe 150. The method for forming the joint portion 180 is not limited thereto, and other methods such as laser welding or ultrasonic welding may be used to form the joint portion 180. The method of joining the film member 160 and the exhaust pipe 150 in the joint portion 180 is not limited to welding, and the film member 160 and the exhaust pipe 150 may be joined using an adhesive or a double-sided tape.

[0077] In this embodiment, if Figure 6 As shown, the membrane member 160 has a first membrane member 161 overlapping in the direction of the gas flow path 250 and a second membrane member 162 overlapping in the direction of the gas flow path 250. In the gas flow path 250, the first membrane member 161 is located on the upstream side, and the second membrane member 162 is located on the downstream side. It should be noted that the surface on the upstream side in the gas flow path 250 can be said to be a surface close to the inside of the outer body 100, or a surface facing the inside of the outer body 100. The first membrane member 161 is a member having a mesh structure with high air permeability. The first membrane member 161 is formed, for example, of a non-woven fabric made of PET. The second membrane member 162 is a porous member having lower air permeability than the first membrane member 161. The second membrane member 162 is formed, for example, of a porous membrane made of PTFE. Thus, the second membrane member 162 has air permeability and moisture permeability, and has a waterproof function. That is, in this embodiment, the membrane member 160 is, for example, a member called a breathable waterproof membrane. The waterproof function mentioned here refers to limiting the inflow or penetration of water (including seawater, river water, rainwater) from the outside of the outer body 100 to the inside. It is preferred that this function also be provided for liquids other than water (oil, etc.). It should be noted that the liquid permeability of the first membrane member 161 and the second membrane member 162 can be measured in accordance with JIS C0920:2003. In this embodiment, the case where the waterproof function is provided is exemplified, but the oil-proof function, the hydrophobic function, the oleophobic function, and the function of combining these functions may also be provided.

[0078] As described above, the first film member 161 and the second film member 162 constituting the film member 160 are both breathable, so that the passage of external gas (air) is allowed in the film member 160 under normal circumstances. However, in the film member 160, the second film member 162 located on the outside (close to the outside of the outer body 100) is waterproof. Therefore, the inflow of water into the interior of the outer body 100 through the exhaust pipe 150 is effectively suppressed by the second film member 162. Since the first film member 161 has a higher tensile strength than the second film member 162, it plays a role in improving the mechanical strength of the film member 160. It should be noted that the tensile strength of the first film member 161 and the second film member 162 can be measured in accordance with JIS K7127:1999.

[0079] In the power storage device 10 having the membrane member 160 configured in this way, when the gas discharge valve 231 of the power storage element 200 is opened and gas is discharged from the power storage element 200, the internal pressure of the outer casing 100 rises sharply. As a result, the membrane member 160 disposed at the front end portion 155 of the exhaust pipe 150 is Figure 7 as well as Figure 8 Change the shape and posture as shown.

[0080] Specifically, when gas is discharged from the power storage element 200, the internal pressure of the outer casing 100 rises rapidly. Figure 7 As shown, the membrane member 160 expands toward the downstream side of the gas flow path 250 (toward the outside of the outer body 100). At this time, the second membrane member 162, which has lower air permeability than the first membrane member 161, is subjected to a greater pressure (pressure toward the downstream of the gas flow path 250) than the first membrane member 161. In addition, the second membrane member 162 has a characteristic that the tensile strength is lower than that of the first membrane member 161. As a result, Figure 8 As shown, at least the second film member 162 of the first film member 161 and the second film member 162 is broken. As a result, the flow resistance caused by at least the second film member 162 is reduced compared to before the second film member 162 is broken. In other words, the flow resistance caused by the film member 160 is reduced compared to before the second film member 162 is broken. As a result, the gas inside the outer body 100 is discharged to the outside of the outer body 100 via the exhaust pipe 150. In other words, a flow path 250 of the gas from the inside of the outer body 100 to the outside of the exhaust pipe 150 is formed, thereby stopping the rise of the internal pressure of the outer body 100 and reducing it.

[0081] Figure 7 as well as Figure 8 The change in posture and shape of the film member 160 shown in FIG. 1 is an example. When gas is discharged from the power storage element 200, the change in posture and shape of the film member 160 may be different from Figure 7 as well as Figure 8 When gas is discharged from the power storage element 200, a portion of the second film member 162 does not necessarily have to be broken (see Figure 8 ) and eventually falls off. A portion of the second film member 162 may be maintained in a state of being connected to other portions, or both the second film member 162 and the first film member 161 may be broken. The second film member 162 may also melt or fuse due to the heat of the gas discharged from the energy storage element 200. At least one of the first film member 161 and the second film member 162 may be peeled off from the end wall portion 156. In either case, when the internal pressure of the outer body 100 rises sharply, the flow resistance brought by the film member 160 is reduced (including the case where the flow resistance is zero), thereby promoting the rapid discharge of the gas inside the outer body 100 to the outside of the outer body 100.

[0082] As described above, the power storage device 10 according to the present embodiment includes the power storage element 200, the outer casing 100 accommodating the power storage element 200, the exhaust pipe 150, and the film member 160. The exhaust pipe 150 forms a part of the gas flow path 250 when the gas is exhausted from the power storage element 200, and is a part of the gas flow path 250 that connects the inside of the outer casing 100 with the outside of the outer casing 100. The film member 160 blocks the gas flow path 250 at the front end portion 155 of the exhaust pipe 150 close to the outside, and has air permeability.

[0083] According to this structure, the front end portion 155 of the exhaust pipe 150 is blocked by the membrane member 160 under normal circumstances, thereby suppressing the intrusion of foreign matter such as water into the interior of the outer body 100. The membrane member 160 has air permeability, and thus can allow ventilation for pressure balance between the outside of the outer body 100 and the inside of the outer body 100 under normal circumstances. The membrane member 160 having the above-mentioned function is arranged at the front end portion 155 of the exhaust pipe 150, so it is easy to arrange the membrane member 160 to the exhaust pipe 150 or to inspect it based on visual observation from the outside. Therefore, according to the power storage device 10 involved in this embodiment, it is easy to improve reliability.

[0084] In the power storage device 10 according to the present embodiment, when gas is discharged from the power storage element 200, at least a portion of the film member 160 is broken or dropped due to the pressure of the gas, so that the gas flow path 250 can be substantially opened. As a result, the gas inside the outer body 100 can be discharged to the outside of the outer body 100. The film member 160 is arranged at the front end portion 155 of the exhaust pipe 150, so as described above, the exhaust pipe 150 can be easily arranged or inspected, and the film member 160 can also be easily replaced or cleaned. Maintenance work such as maintenance.

[0085] In the present embodiment, the membrane member 160 includes a first membrane member 161 which overlaps in the direction of the gas flow path 250 and has air permeability, and a second membrane member 162 which overlaps in the direction of the gas flow path 250 and has air permeability. The second membrane member 162 is located downstream (closer to the outside of the outer body 100) than the first membrane member 161 in the gas flow path 250, and the air permeability of the second membrane member 162 is lower than the air permeability of the first membrane member 161.

[0086] As described above, the membrane member 160 involved in the present embodiment has at least two layers (a first membrane member 161 and a second membrane member 162). As a result, it is easy to improve the mechanical strength of the membrane member 160 against foreign matter or pressure from the outside. Therefore, the membrane member 160 exposed to the external space or arranged at a position close to the external space is more reliably protected. As a result, the reliability of the power storage device 10 relative to the external space of the power storage device 10 can be more reliably improved. In addition, in the membrane member 160 having at least two layers, the second membrane member 162 arranged on the downstream side of the gas flow path 250 (a position close to the outside of the outer body 100) has lower air permeability than the first membrane member 161. Therefore, in the case where gas is discharged from the storage element 200, it is preferred that at least the second membrane member 162 is broken due to the pressure of the gas from the upstream to the downstream. As a result, the flow path resistance brought by the membrane member 160 to the gas to be discharged to the outside is reduced. As a result, the gas inside the outer body 100 can be quickly discharged to the outside.

[0087] In the present embodiment, the tensile strength of the first film member 161 is higher than that of the second film member 162 , and the liquid permeability of the second film member 162 is lower than that of the first film member 161 .

[0088] As described above, the membrane member 160 is formed by combining two members having different characteristics, so that the two members respectively give the membrane member 160 different useful characteristics. Specifically, the first membrane member 161 can improve the mechanical strength of the membrane member 160, and the second membrane member 162 can improve the function of the membrane member 160 as a waterproof membrane. Therefore, the membrane member 160 maintains a good state. As a result, the reliability of the power storage device 10 relative to the internal space of the power storage device 10 and the external space of the power storage device 10 can be more reliably improved.

[0089] In the present embodiment, the film member 160 is bonded to the outer surface 157 of the front end portion 155 of the exhaust pipe 150 and to the outer surface 157 on the downstream side (direction toward the outside of the exterior body 100 ) in the gas flow path 250 .

[0090] As described above, the film member 160 is bonded to the outer surface 157 of the downstream side of the gas flow path 250 of the exhaust pipe 150, and thus has high resistance to external forces from the downstream side toward the upstream side. Therefore, the film member 160 is prevented from peeling off or falling off from the exhaust pipe 150 due to an increase in the external pressure of the outer body 100 or a collision of foreign matter such as water with the film member 160.

[0091] In this embodiment, if Figure 4 as well as Figure 5 As shown, the exhaust pipe 150 includes an end wall portion 156 provided at a front end portion 155, and a through hole 158 for passing gas is formed in the end wall portion 156. The film member 160 is joined to the end wall portion 156 in a state where the through hole 158 is blocked.

[0092] According to this structure, even when the outer diameter of the exhaust pipe 150 is large, the size of the membrane member 160 only needs to be a size that can block the through hole 158 of the end wall portion 156. Therefore, it is not necessary to prepare a large-sized membrane member 160 that matches the outer diameter of the exhaust pipe 150. In other words, the membrane member 160 can be formed into a smaller size, thereby reducing the material required for manufacturing the membrane member 160.

[0093] In this embodiment, if Figure 4 as well as Figure 5 As shown, the exhaust pipe 150 has a protruding portion 153 disposed at a front end portion 155 , and the protruding portion 153 protrudes toward the downstream side (toward the outside of the exterior body 100 ) in the gas flow path 250 relative to the membrane member 160 .

[0094] That is, the film member 160 is arranged at a position further back (in the negative direction of the X axis) than the front end (in the positive direction of the X axis) of the protrusion 153. Figure 4 as well as Figure 5 ) is located at a position that is further back (in the negative direction of the X-axis) than the end face of the front end portion 155 of the exhaust pipe 150 (i.e., the end face of the protrusion 153 in the positive direction of the X-axis). In this way, by having a protrusion 153 that protrudes outward (toward the outside of the outer casing) compared to the membrane member 160, the membrane member 160 is more reliably protected. Specifically, when the power storage device 10 is assembled, transported, or installed, the membrane member 160 is prevented from coming into contact with external objects or a human body. That is, the functions of the membrane member 160 (the waterproofing function and the internal and external pressure balancing function in normal times, or / and the gas discharge function in an emergency, the same below) are more reliably maintained.

[0095] The protrusion 153 may be formed integrally with the exhaust pipe 150 or may be a member different from the exhaust pipe 150 (an independent component). When the protrusion 153 is an independent component, the protrusion 153 may be attached to the exhaust pipe 150 by bonding, welding, screwing, or fitting one of the exhaust pipe 150 and the protrusion 153 to the other. The protrusion 153 may be detachable from the exhaust pipe 150. When the protrusion 153 is an independent component, the length L of the exhaust pipe 150 (see Figure 5 ) may be the length before the protrusion 153 is installed. That is, the protrusion 153 may be installed on the exhaust pipe 150 after the membrane member 160 is installed on the front end portion 155 of the exhaust pipe 150.

[0096] In the above, the power storage device 10 according to the embodiment is described mainly with respect to the exhaust pipe 150 and the structure of its periphery. However, the exhaust pipe 150 and the structure of its periphery in the power storage device 10 may be different from the exhaust pipe 150. Figure 4~Figure 8 Therefore, below, a modified example of the structure of the exhaust pipe 150 and its surroundings will be described, focusing on the differences from the above-mentioned embodiment.

[0097] [4-1. Modification 1]

[0098] Fig. 9 It is a cross-sectional view showing a front end portion 155a of an exhaust pipe 150a according to Modification 1 of the embodiment. Fig. 9 The position of the section in Figure 5 This is important for the following Figure 10~Figure 12 The same is true for .

[0099] Fig. 9 The exhaust pipe 150a shown in the figure can be provided in the outer casing 100 (see Figure 5 ) to form a part of the gas flow path 250. On the exhaust pipe 150a, a membrane member 160 is arranged at the front end portion 155a of the exhaust pipe 150a to block the gas flow path 250. Specifically, the membrane member 160 is joined to the outer surface 157a of the end wall portion 156a in a state where the through hole 158a formed in the end wall portion 156a provided at the front end portion 155a is blocked. The above structure is common to the exhaust pipe 150 involved in the embodiment.

[0100] The exhaust pipe 150a according to the present modification is different from the exhaust pipe 150 according to the embodiment in that the outer surface 157a of the end wall portion 156a forms the end surface (the side surface in the positive direction of the X axis) of the front end portion 155a. That is, the exhaust pipe 150a is not provided with a protrusion that protrudes toward the downstream side (toward the outside of the outer body 100) in the gas flow path 250 relative to the membrane member 160. Even in this case, the function of the membrane member 160 can be exerted, and the arrangement operation, inspection, or maintenance operation of the exhaust pipe 150a of the membrane member 160 can be performed more easily.

[0101] [4-2. Modification 2]

[0102] Fig.10 It is a cross-sectional view showing a front end portion 155b of an exhaust pipe 150b according to a second modification of the embodiment. Fig.10 The exhaust pipe 150b shown in the figure can be provided in the outer casing 100 (see Figure 5 ) to form a part of the gas flow path 250. On the exhaust pipe 150b, a membrane member 160 is arranged at the front end portion 155b of the exhaust pipe 150b to block the gas flow path 250. Specifically, the membrane member 160 is joined to the outer surface 157b of the front end portion 155b, and the outer surface 157b is the outer surface 157b of the downstream side (toward the outside of the outer body 100) in the gas flow path 250. The above structure is common to the exhaust pipe 150 involved in the embodiment.

[0103] The exhaust pipe 150b according to the present modification does not have the end wall portion 156 (see Figure 4 as well as Figure 5 ) is different from the exhaust pipe 150 involved in the embodiment in that the wall portion extends in a direction perpendicular to the gas flow path 250. That is, the exhaust pipe 150b is a simple straight pipe shape, such as Fig.10 As shown in FIG. 1 , the through hole 158b opened at the front end portion 155b extends along the tube axis direction (X-axis direction) of the exhaust pipe 150b, and is a hole whose inner diameter is substantially constant in the X-axis direction. In this modified example, the membrane member 160 is joined to the front end face, i.e., the outer surface 157b, of the exhaust pipe 150b formed in a straight tube shape as described above, thereby blocking the gas flow path 250. Even in this case, the function of the membrane member 160 can be exerted, and the configuration operation, inspection or maintenance operation of the exhaust pipe 150b of the membrane member 160 can be performed more easily.

[0104] [4-3. Modification 3]

[0105] Fig.11It is a cross-sectional view showing a front end portion 155c of an exhaust pipe 150c according to Modification 3 of the embodiment. Fig.11 The exhaust pipe 150c shown in the figure can be provided in the outer casing 100 (see Figure 5 ) to form a part of the gas flow path 250. On the exhaust pipe 150c, a membrane member 160 is arranged at the front end portion 155c of the exhaust pipe 150c to block the gas flow path 250. Specifically, the membrane member 160 is joined to the outer surface 157c of the end wall portion 156c in a state where the through hole 158c formed in the end wall portion 156c provided at the front end portion 155c is blocked. The above structure is common to the exhaust pipe 150 involved in the embodiment.

[0106] The exhaust pipe 150c according to the present modification is different from the exhaust pipe 150 according to the embodiment in that the film member 160 is arranged in a posture not orthogonal to the extending direction of the exhaust pipe 150c.

[0107] According to this structure, the membrane member 160 is arranged obliquely with respect to the extension direction of the exhaust pipe 150c, that is, the direction of the flow path 250 of the gas inside the exhaust pipe 150c (X-axis direction). More specifically, in this embodiment, the angle formed by the thickness direction of the membrane member 160 and the extension direction (X-axis direction) of the exhaust pipe 150c is greater than 0° and less than 90°. Therefore, compared with the case where the membrane member 160 is in a posture orthogonal to the X-axis direction, the area of ​​the membrane member 160 that can be ventilated becomes larger. In other words, as a result, the pressure balance between the outside of the outer body 100 and the inside of the outer body 100 is more smoothly performed. In this embodiment, the end wall portion 156c is arranged in a posture that is not orthogonal to the extension direction of the exhaust pipe 150c, and the outer surface 157c of the end wall portion 156c is also inclined with respect to the direction of the flow path 250 of the gas (X-axis direction). As a result, the inner diameter D of the through hole 158c opened on the outer surface 157c can be made larger. That is, the opening area of ​​the through hole 158c as the outlet of the gas from the exhaust pipe 150c can be increased. Thus, when the gas is exhausted from the energy storage element 200, the gas is exhausted to the outside from the exhaust pipe 150c more smoothly.

[0108] [4-4. Modification 4]

[0109] Fig.12 It is a cross-sectional view showing a front end portion 155d of an exhaust pipe 150d according to Modification 4 of the embodiment. Fig.12 The exhaust pipe 150d shown in the figure can be provided in the outer casing 100 (see Figure 5) to form a part of the gas flow path 250. On the exhaust pipe 150d, a membrane member 160 is arranged at the front end portion 155d of the exhaust pipe 150d to block the gas flow path 250. Specifically, the membrane member 160 is joined to the outer surface 157d of the front end portion 155d, and the outer surface 157d is the outer surface 157d on the downstream side (toward the outside of the outer body 100) in the gas flow path 250. In other words, the opening in the front end portion 155d of the through hole 158d is covered by the membrane member 160. The above structure is common to the exhaust pipe 150 involved in the embodiment.

[0110] The exhaust pipe 150d involved in this modification has a flange portion 159 provided at the front end portion 155d, the flange portion 159 protruding outward in the radial direction of the exhaust pipe 150d, and the film member 160 is joined to the flange portion 159. In this structure, the exhaust pipe 150d involved in this modification is different from the exhaust pipe 150 involved in the embodiment. The radial direction of the exhaust pipe 150d refers to the direction passing through the center of the exhaust pipe 150d when viewed from the X-axis direction ( Fig.12 The direction toward the outside in the radial direction of the exhaust pipe 150d refers to the direction in the radial direction of the exhaust pipe 150d and away from the center.

[0111] According to this structure, even when the outer diameter of the exhaust pipe 150d is small, the bonding area between the film member 160 and the front end portion 155d of the exhaust pipe 150d can be ensured. Fig.10 When the outer diameter of the exhaust pipe 150b shown in the figure is reduced, in order to maintain the cross-sectional area of ​​the through hole 158b (the cross-sectional area perpendicular to the X-axis direction), the wall thickness of the exhaust pipe 150b needs to be reduced. As a result, the width of the outer surface 157b (the wall thickness of the exhaust pipe 150b) becomes smaller, and thus, it may become difficult to join the membrane member 160 to the outer surface 157b. Fig.12 As shown in FIG. 1 , the exhaust pipe 150d according to the present modification has a flange portion 159 protruding outward. That is, the film member 160 can be joined to the outer surface (the surface facing the outside of the outer body 100) 157d of the flange portion 159. Therefore, the joining area between the film member 160 and the front end portion 155d can be ensured without depending on the size of the outer diameter of the exhaust pipe 150d and the size of the wall thickness of the exhaust pipe 150d.

[0112] [5. Other Modifications]

[0113] The above describes the power storage device involved in the embodiment of the present invention and its modified example, but the present invention is not limited to the embodiment and modified example. In other words, it should be considered that the embodiment disclosed this time is illustrative rather than restrictive in all aspects. The scope of the present invention is intended to include the meaning equivalent to the technical solution and all changes within the scope.

[0114] The power storage device 10 may not include the path forming portion 319 provided on the bus bar holder 300. The bus bar holder 300 may include one or more through holes for allowing gas to pass through in the Z-axis direction within a range including a region facing the gas discharge valves 231 of each of the plurality of power storage elements 200. In other words, the gas discharged from at least one of the plurality of power storage elements 200 may move inside the outer casing 100 without being restricted by the path forming portion 319.

[0115] The power storage device 10 may not include the bus bar holder 300. When positioning of the plurality of bus bars 400 is easy or the plurality of power storage elements 200 are protected by insulating members such as cell holders, the plurality of bus bars 400 may be arranged at predetermined positions without the bus bar holder 300.

[0116] The exhaust pipe 150 is not necessarily arranged on the cover 120 of the outer casing 100. The exhaust pipe 150 may be arranged at any position other than the cover 120 of the outer casing 100. The arrangement position and posture of the exhaust pipe 150 in the outer casing 100 may be appropriately determined according to the arrangement of the gas pipe connected to the exhaust pipe 150 or the posture of the outer casing 100 when the power storage device 10 is used.

[0117] The size and shape of the exhaust pipe 150 are not limited to Figure 4 as well as Figure 5 The exhaust pipe 150 may also have a convex portion, a concave portion, a movable portion, etc. for connecting to the gas pipe. Figure 4 as well as Figure 5 Elements not shown in the figure.

[0118] The size and shape of the through hole 158 when viewed from the X-axis direction and the size and shape of the membrane member 160 when viewed from the X-axis direction (see Figure 4 as well as Figure 5 ) is not particularly limited. The above-mentioned size and shape can be any size and shape as long as the membrane member 160 can block the through hole 158. In this way, the function of the membrane member 160 is exerted. The size and shape of the membrane member 160 may also be the size and shape exposed from the exhaust pipe 150 when viewed from the X-axis direction, but it is preferably the size and shape not exposed from the exhaust pipe 150.

[0119] The membrane member 160 is not necessarily a breathable waterproof membrane. The membrane member 160 only needs to be breathable, and does not necessarily have waterproof properties like the porous membrane used as the second membrane member 162. The membrane member 160 is an object that is at least breathable, so it can allow ventilation for pressure balance between the outside of the outer body 100 and the inside of the outer body 100 in normal times, and it can make it difficult for foreign matter to invade the inside of the outer body 100 from the outside of the outer body 100. In addition, when gas is discharged from the power storage element 200, the membrane member 160 breaks, melts, melts, or / and moves with a sharp increase in the internal pressure of the outer body 100, thereby forming a gas flow path 250 from the inside of the outer body 100 to the outside of the exhaust pipe 150.

[0120] The membrane member 160 is not necessarily formed by overlapping a plurality of membrane members. For example, the membrane member 160 may be formed only by a membrane member having high air permeability such as the first membrane member 161. When the membrane member 160 is formed by one membrane member, the membrane member may have both air permeability and waterproofness.

[0121] The stacking order of the first film member 161 and the second film member 162 in the first film member 160 may also be the same as Figure 6 The stacking order shown is opposite. That is, in the gas flow path 250, the first membrane member 161 may be located on the downstream side (a position close to the outside of the outer body 100), and the second membrane member 162 may be located on the upstream side (a position close to the inside of the outer body 100). Even in this case, under normal circumstances, the front end portion 155 of the exhaust pipe 150 is also blocked by the membrane member 160, thereby suppressing the intrusion of foreign matter such as water into the inside of the outer body 100. The membrane member 160 has air permeability, and thus can allow ventilation for pressure balance between the outside of the outer body 100 and the inside of the outer body 100 under normal circumstances.

[0122] The above-mentioned supplementary matters regarding the exhaust pipe 150 according to the embodiment can also be appropriately applied to each of the exhaust pipes 150a to 150d according to Modifications 1 to 4. The scope of the present invention also includes a configuration in which the components included in the above-mentioned embodiment and its modifications are arbitrarily combined.

[0123] Industrial Applicability

[0124] The present invention can be applied to a power storage device including a power storage element such as a lithium ion secondary battery, and the like.

[0125] Description of Reference Numerals

[0126] 10 Power storage device

[0127] 100 outer body

[0128] 150, 150a, 150b, 150c, 150d Exhaust pipe

[0129] 153 Protrusion

[0130] 155, 155a, 155b, 155c, 155d front end

[0131] 156, 156a, 156c End wall portion

[0132] 157, 157a, 157b, 157c, 157d outer surface

[0133] 158, 158a, 158b, 158c, 158d through hole

[0134] 159 flange

[0135] 160 membrane components

[0136] 161 First membrane component

[0137] 162 Second membrane component

[0138] 180 Joint

[0139] 200 Storage Components

[0140] 250 Gas flow path.

Claims

1. A power storage device, wherein: The power storage device comprises: Storage element; an outer casing that houses the power storage element; an exhaust pipe connecting the interior of the outer casing with the exterior of the outer casing and forming a part of a flow path of the gas; as well as A membrane member blocks the flow path of the gas at a front end portion of the exhaust pipe close to the outside and has air permeability.

2. The power storage device according to claim 1, wherein The membrane member includes a first membrane member that overlaps in the direction of the flow path of the gas and has air permeability, and a second membrane member that overlaps in the direction of the flow path of the gas and has air permeability. The second film member is arranged in the flow path of the gas at a position closer to the outside than the first film member. The air permeability of the second film member is lower than the air permeability of the first film member.

3. The power storage device according to claim 2, wherein: The tensile strength of the first film member is higher than the tensile strength of the second film member, The second film member has lower liquid permeability than the first film member.

4. The power storage device according to any one of claims 1 to 3, wherein: The film member is joined to an outer surface of the front end portion of the exhaust pipe, the outer surface being an outer surface close to the outside in the flow path of the gas.

5. The power storage device according to any one of claims 1 to 3, wherein: The film member is inclined with respect to an extending direction of the exhaust pipe.

6. The power storage device according to any one of claims 1 to 3, wherein: The exhaust pipe has a flange portion provided at the front end portion, and the flange portion protrudes outward in a radial direction of the exhaust pipe. The film member is engaged with the flange portion.

7. The power storage device according to any one of claims 1 to 3, wherein: The exhaust pipe has an end wall portion provided at the front end portion, and the end wall portion is formed with a through hole for allowing the gas to pass through. The film member is joined to the end wall portion in a state where the through hole is blocked.

8. The power storage device according to any one of claims 1 to 3, wherein: The exhaust pipe has a protruding portion disposed at the front end portion, and the protruding portion protrudes toward the outside rather than an outer surface of the film member close to the outside.

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