Energy storage device

Abstract

To provide an energy storage device with improved reliability. [Solution] The energy storage device 1 comprises an outer casing 10 and an energy storage element housed inside the outer casing. The outer casing includes a ventilation chamber 100 connecting the inside and outside of the outer casing. The ventilation chamber includes a through hole 115 connected to the inside of the outer casing, a first wall portion 110 with a through hole penetrating in a first direction, a membrane member 200 that closes the through hole, a side wall portion 150 positioned to surround the through hole, a side wall portion with an opening connecting the inside of the ventilation chamber to the outside of the outer casing, and a second wall portion 132 positioned between the opening and the through hole. The inside of the ventilation chamber is located in one direction from the first wall portion, and a gap G is formed between the second wall portion and the inner surface of the ventilation chamber. At least a part of the gap, the first gap Ga, is located in the other direction from the membrane member.

Description

Technical Field

[0001] The present invention relates to a power storage device.

Background Art

[0002] The battery pack disclosed in Patent Document 1 includes a battery module, an electrical component unit, and a housing. Inside the housing, a first accommodation space for accommodating the battery module and a second accommodation space for accommodating the electrical component unit are provided. In a portion of the housing that forms the second accommodation space, a duct that communicates the second accommodation space with the outside of the housing is provided. A filter for closing the gas passage of the duct is provided in the duct. The filter opens the gas passage of the duct when the gas pressure in the second accommodation space becomes a predetermined value or more with respect to the atmospheric pressure outside the housing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional battery pack, the filter is composed of a circular sheet made of a resin material that does not have gas permeability but has moisture permeability and waterproofness. Therefore, the filter prevents foreign matter and water from entering the battery pack from the outside. However, since the filter is disposed at the tip of the duct, a liquid such as water is likely to come into contact with the filter. Therefore, there is a risk that the filter to which the liquid adheres may deteriorate or be damaged.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to provide a power storage device with improved reliability.

Means for Solving the Problems

[0006] An energy storage device according to one aspect of the present invention comprises an outer casing and an energy storage element housed inside the outer casing, wherein the outer casing includes a ventilation chamber connecting the inside and outside of the outer casing, the ventilation chamber includes a through hole connected to the inside of the outer casing, a first wall portion having a through hole penetrating in a first direction, a membrane member closing the through hole, a side wall portion positioned to surround the through hole, a side wall portion having an opening connecting the inside of the ventilation chamber to the outside of the outer casing, and a second wall portion positioned between the opening and the through hole, wherein the inside of the ventilation chamber is located in one direction from the first wall portion, a gap is formed between the second wall portion and the inner surface of the ventilation chamber, and at least a part of the gap, the first gap, is located in the other direction from the membrane member. [Effects of the Invention]

[0007] According to the present invention, an energy storage device with improved reliability can be provided. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage device according to an embodiment. [Figure 2] Figure 2 is an exploded perspective view of the energy storage device according to the embodiment. [Figure 3] Figure 3 is an exploded perspective view showing the configuration of the ventilation chamber according to the embodiment. [Figure 4] Figure 4 is a perspective view showing the configuration of the third wall portion according to the embodiment. [Figure 5] Figure 5 is a plan view showing the internal configuration of the ventilation chamber according to the embodiment. [Figure 6] Figure 6 is a plan view showing the position of the second wall portion in the ventilation chamber according to the embodiment. [Figure 7] Figure 7 is a first cross-sectional view of the ventilation chamber according to the embodiment. [Figure 8] Figure 8 is a second cross-sectional view of the ventilation chamber according to the embodiment. [Figure 9]Figure 9 is a third cross-sectional view of the ventilation chamber according to the embodiment. [Figure 10] Figure 10 is a cross-sectional view of a ventilation chamber according to a modified example of the embodiment. [Modes for carrying out the invention]

[0009] (1) An energy storage device according to one aspect of the present invention comprises an outer casing and an energy storage element housed inside the outer casing, wherein the outer casing includes a ventilation chamber connecting the inside and outside of the outer casing, the ventilation chamber includes a through hole connected to the inside of the outer casing, a first wall portion having a through hole penetrating in a first direction, a membrane member closing the through hole, a side wall portion positioned to surround the through hole, a side wall portion having an opening connecting the inside of the ventilation chamber to the outside of the outer casing, and a second wall portion positioned between the opening and the through hole, wherein the inside of the ventilation chamber is located in one direction from the first wall portion, a gap is formed between the second wall portion and the inner surface of the ventilation chamber, and at least a part of the gap, the first gap, is located in the other direction from the membrane member.

[0010] According to one embodiment of the present invention, gas exchange between the inside and outside of the outer casing can occur through through-holes provided in the ventilation chamber. In the ventilation chamber, a second wall is positioned between the opening and the through-hole, so that liquid entering from the opening does not reach the membrane member. Since there is a gap between the second wall and the inner surface of the ventilation chamber, gas exchange between the inside and outside of the outer casing can occur through this gap. Furthermore, in the first direction, the position of the first gap, which is at least a part of the gap, is on the other side of the first direction (closer to the inside of the outer casing) than the membrane member. Therefore, even if liquid reaches the first gap from the opening, the liquid reaching the membrane member from the first gap is suppressed. Consequently, deterioration or damage to the membrane member due to liquid adhering to it is suppressed. Thus, the energy storage device according to this embodiment is an energy storage device with improved reliability.

[0011] (2) In the power storage device described in (1) above, the ventilation chamber may include a third wall portion facing the first wall portion in the first direction, and one end portion of the second wall portion in the first direction may be connected to the third wall portion.

[0012] According to the power storage device described in (2) above, since one end portion of the second wall portion in the first direction is connected to the third wall portion, a gap cannot be formed at this end portion. Therefore, it becomes difficult for the liquid that has entered from the opening to reach the membrane member.

[0013] (3) In the power storage device described in (1) or (2) above, the first gap may be formed between the edge of the second wall portion in the first direction and the inner surface, and the width of the first gap in the first direction may increase as it approaches the opening.

[0014] According to the power storage device described in (3) above, since the width of the first gap increases as it approaches the opening, the flow of the liquid that has entered the first gap toward the opening can be promoted. Therefore, the liquid that has entered the ventilation chamber can be efficiently discharged from the opening. As a result, it becomes difficult for the liquid that has entered from the opening to reach the membrane member.

[0015] (4) In the power storage device described in any one of (1) to (3) above, the side wall portion may include a first inclined surface facing the inside of the ventilation chamber, and the first inclined surface may be inclined in a direction approaching the outside of the exterior body as it approaches the opening.

[0016] According to the power storage device described in (4) above, when the power storage device is arranged in a posture where the opening faces downward, that is, a posture where the first direction is parallel to the horizontal direction, the liquid that has entered the ventilation chamber from the opening is easily discharged to the outside of the exterior body by the first inclined surface. As a result, it becomes difficult for the liquid that has entered from the opening to reach the membrane member.

[0017] (5) In the power storage device according to any one of (1) to (4) above, the ventilation chamber includes a second inclined surface disposed on the other side in the first direction with respect to the second wall portion, and the second inclined surface may be inclined in a direction advancing toward the other side in the first direction as it approaches the opening.

[0018] According to the power storage device described in (5) above, when the power storage device is arranged in a posture where the other side in the first direction faces downward, the liquid that has entered the interior of the ventilation chamber from the opening is easily discharged to the outside of the exterior body by the second inclined surface. As a result, it becomes more difficult for the liquid that has entered from the opening to reach the film member.

[0019] Hereinafter, a power storage device according to an embodiment (including its modified examples) of the present invention will be described with reference to the drawings. The embodiments described below are all illustrative of comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. In each figure, dimensions, shapes, etc. are not strictly illustrated and may be appropriately emphasized and omitted. In each figure, the same or similar components are denoted by the same reference numerals.

[0020] In the following description and drawings, the arrangement direction of a pair of external terminals included in the exterior body of the power storage device is defined as the X-axis direction. The arrangement direction of a plurality of power storage elements included in the power storage device, the thickness direction of the power storage element, or the arrangement direction of the lid body and the exterior body main body in the exterior body is defined as the Y-axis direction. The arrangement direction of a pair of terminals in one power storage element is defined as the Z-axis direction. These X-axis direction, Y-axis direction and Z-axis direction are directions that intersect (orthogonal in this embodiment) with each other. In FIGS. 1 and 2, the power storage device is illustrated with the Z-axis direction as the vertical direction, but depending on the usage mode of the power storage device, the Z-axis direction may not be the vertical direction.

[0021] In the following explanation, the X-axis positive direction refers to the direction of the X-axis arrow, and the X-axis negative direction refers to the opposite direction. One side of the X-axis direction (also called "one side") means either the X-axis positive direction or the X-axis negative direction. If one side of the X-axis direction is the X-axis positive direction, the other side of the X-axis direction (also called "the other side") is the X-axis negative direction. If one side of the X-axis direction is the X-axis negative direction, the other side of the X-axis direction is the X-axis positive direction. When simply referring to the X-axis direction, it refers to either the X-axis positive direction or the X-axis negative direction, or either direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. Two directions being parallel means not only that the two directions are perfectly parallel, but also that they are substantially parallel, i.e., that they include a difference of a few percent. Furthermore, in the following explanation, when "insulation" is used, it means "electrical insulation". Insulating materials have a volume resistivity of 1 × 10⁻⁶ 6 Ωm or greater, more preferably 1 × 10⁻⁶ 7 Ωm or greater, more preferably 1 × 10⁻⁶ 10 It is preferable that the material is formed from a material with a density of Ωm or greater.

[0022] (Embodiment) [1. General description of the energy storage device 1] First, a general description of the energy storage device 1 according to the embodiment will be given using Figures 1 and 2. Figure 1 is a perspective view showing the external appearance of the energy storage device 1 according to the embodiment. Figure 2 is an exploded perspective view of the energy storage device 1 according to the embodiment.

[0023] The energy storage device 1 is a device that can charge electricity from an external source and discharge electricity to the outside. In this embodiment, the energy storage device 1 has a substantially rectangular parallelepiped shape. A rectangular parallelepiped, as used here, is a hexahedron whose faces are all rectangles or squares. The energy storage device 1 is a battery module (battery pack) used for power storage or power supply purposes. Specifically, the energy storage device 1 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, automated guided vehicles (AGVs), or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, linear motor cars, and hybrid trains equipped with both diesel engines and electric motors. The energy storage device 1 can also be used as a stationary battery for household or commercial use.

[0024] As shown in Figures 1 and 2, the energy storage device 1 comprises an energy storage unit 51, a holding member 30, and an outer casing 10 that houses the energy storage unit 51 and the holding member 30. The holding member 30 holds a circuit board 80 and the like. The outer casing 10 has an outer casing body 12 and a lid 20 that closes the outer casing body 12.

[0025] The outer casing 10 is a roughly rectangular parallelepiped (box-shaped) case that constitutes the outer shell of the energy storage device 1. The outer casing 10 protects the energy storage unit 51 and other components housed inside from impacts and other damage. The outer casing body 12 is a bottomed rectangular cylindrical member having an opening 12a in the negative Y-axis direction. The energy storage unit 51 and a holding member 30 that holds a circuit board 80 electrically connected to the energy storage unit 51 are housed inside the opening 12a of the outer casing body 12.

[0026] The cover 20 is a component that closes the opening 12a of the outer casing body 12. The cover 20 is joined to the outer casing body 12 in a manner that closes the opening 12a of the outer casing body 12 from the negative Y-axis direction. Adhesives, heat seals (thermal welding), ultrasonic welding, laser welding, etc., are used to join the cover 20 to the outer casing body 12. This maintains airtightness at the joint between the cover 20 and the outer casing body 12. The cover 20 and the outer casing body 12 may also be joined by crimping or screw fastening. In this case, airtightness at the joint between the cover 20 and the outer casing body 12 may be maintained by placing a gasket between the cover 20 and the outer casing body 12. The cover 20 has a pair (positive and negative) of external terminals 90. The external terminals 90 are electrically connected to a plurality of energy storage elements 50 included in the energy storage unit 51. The energy storage device 1 charges itself with electricity from an external source via a pair of external terminals 90, and also discharges electricity to the outside.

[0027] The external terminals 90 are formed from conductive materials such as brass or other copper alloys, copper, aluminum, aluminum alloys, nickel, or a combination thereof, or from conductive materials other than metal. When distinguishing between a pair of external terminals 90, the positive external terminal 90 is referred to as external terminal 90A, and the negative external terminal 90 is referred to as external terminal 90B. External terminal 90A is electrically connected to the total positive terminal of the energy storage unit 51 via a busbar or the like (not shown). External terminal 90B is electrically connected to the total negative terminal of the energy storage unit 51 via a busbar or the like (not shown).

[0028] The outer casing body 12 and lid 20 of the outer casing 10 are formed from insulating materials 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 perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or composite materials thereof, or from metal with an insulating coating. This prevents the energy storage unit 51, etc. from coming into contact with external metal components, etc. The outer casing 10 may be formed from a conductive material such as metal, as long as the electrical insulation of the energy storage unit 51, etc. is maintained. The outer casing body 12 and the lid 20 may be made of the same material or of different materials.

[0029] In this embodiment, the outer casing 10 is equipped with a ventilation chamber 100 that connects the inside and outside of the outer casing 10. Specifically, the ventilation chamber 100 is provided in a part of the lid 20. The ventilation chamber 100 includes a through hole 115 connected to the inside of the outer casing 10, a membrane member 200 that closes the through hole 115, and a third wall portion 130 which is a cover that covers the internal space of the ventilation chamber 100 from the negative Y-axis direction. As described above, the joint between the lid 20 and the outer casing body 12 is kept airtight. Therefore, ventilation for pressure equilibrium between the inside and outside of the outer casing 10, and / or discharge of gas generated from the energy storage element 50 to the outside of the outer casing 10, is performed through the ventilation chamber 100. The configuration of the ventilation chamber 100 and its surroundings will be described later with reference to Figures 3 to 8.

[0030] The energy storage unit 51 comprises a plurality of energy storage elements 50 arranged in the Z-axis direction. The energy storage elements 50 are secondary batteries (single cells) that can charge and discharge electricity, and more specifically, non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries. In this embodiment, the energy storage elements 50 are pouch-type energy storage elements having a flat shape. In this embodiment, four pouch-type energy storage elements 50 are arranged in the Z-axis direction. The four energy storage elements 50 are electrically connected in series. The electrical connection configuration of the four energy storage elements 50 is not particularly limited, and the four energy storage elements 50 may be connected in series and / or parallel in any combination.

[0031] There are no particular limitations on the number of energy storage elements 50 that the energy storage unit 51 may have. The energy storage unit 51 only needs to have at least one energy storage element 50. The direction in which the multiple energy storage elements 50 in the energy storage unit 51 are arranged is not limited to the Z-axis direction. The direction in which the energy storage elements 50 are arranged may be the X-axis direction or the Y-axis direction. The energy storage unit 51 may further include members not shown in Figure 2, such as spacers arranged along the energy storage elements 50 and holding members that hold the multiple energy storage elements 50.

[0032] The pouch-type energy storage element 50 comprises an outer film 52 and a pair of terminals 55 (positive and negative). When distinguishing between the pair of terminals 55, the positive terminal 55 is referred to as terminal 55A, and the negative terminal 55 is referred to as terminal 55B. Inside the outer film 52 are an electrode body and an electrolyte, etc., which are not shown. As the electrode body, a wound-type electrode body formed by winding electrode plates (positive and negative plates) is used. The electrode body of the energy storage element 50 may be of any form, such as a stacked electrode body formed by stacking multiple flat electrode plates, or a bellows-type electrode body in which the electrode plates are folded in a bellows shape. As for the electrolyte of the energy storage element 50, there are no particular restrictions on its type as long as it does not impair the performance of the energy storage element 50, and any known material can be used as appropriate. The outer film 52 is a sheet-like outer structure made of laminate film, and it contains the electrode body, electrolyte, etc., sealed inside under reduced pressure.

[0033] In the energy storage element 50, if the electrolyte vaporizes rapidly due to heat generation of the electrode body or the like, a part of the outer film 52 may rupture, causing gas to be released from the energy storage element 50. If the internal pressure of the outer casing 10 rises excessively due to the gas released from the energy storage element 50, the gas inside the outer casing 10 is released to the outside of the outer casing 10 through the ventilation chamber 100, as described above. This suppresses damage to the outer casing 10 caused by the rise in internal pressure. As a result, the occurrence of situations that would further worsen the situation, such as gas leaking from unexpected locations in the outer casing 10, is suppressed.

[0034] In this embodiment, terminal 55A of one of two adjacent energy storage elements 50 in the Z-axis direction is joined to terminal 55B of the other energy storage element 50 by a predetermined joining method such as welding or crimping. As a result, four energy storage elements 50 are connected in series. Terminal 55B of the energy storage element 50 at the Y-axis negative end of the four series-connected energy storage elements 50 functions as the total negative terminal of the energy storage unit 51. This total negative terminal, terminal 55B, is electrically connected to the external terminal 90B. Terminal 55A of the energy storage element 50 at the Y-axis positive end of the energy storage unit 51 functions as the total positive terminal of the energy storage unit 51. This total positive terminal, terminal 55A, is electrically connected to the external terminal 90A.

[0035] The energy storage element 50 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, a capacitor, or a battery using a solid electrolyte. The energy storage element 50 may be a primary battery instead of a secondary battery. The energy storage element 50 does not need to be a pouch-type energy storage element, but may be a flat rectangular parallelepiped (square), a polygonal prism shape other than a rectangular parallelepiped, a cylindrical shape, an oblong cylindrical shape, or an elliptical prism shape, etc.

[0036] The retaining member 30 holds the busbar (not shown) and circuit board 80, which are electrically connected to the energy storage unit 51. The retaining member 30 is formed of an insulating material such as PC, PP, PE, PS, or PPS, which are used as the material for the outer casing 10, or of metal with an insulating coating. If electrical insulation is not required for the retaining member 30, the retaining member 30 may be formed of a conductive material such as metal. The retaining member 30 is positioned on the side of the energy storage unit 51 in the negative Y-axis direction.

[0037] The circuit board 80 is a device for detecting the state (temperature, voltage, current, etc.) of each energy storage element 50, and a device for monitoring and controlling the charging and discharging states of multiple energy storage elements 50. The circuit board 80 includes multiple electronic components (not shown). In this embodiment, the circuit board 80 is electrically connected to the total negative terminal and the external terminal 90B of the energy storage unit 51. In other words, the circuit board 80 electrically connects the total negative terminal and the external terminal 90B of the energy storage unit 51. The circuit board 80 may be located outside the casing 10. In other words, the device for detecting the state (temperature, voltage, current, etc.) of one or more energy storage elements 50 provided in the energy storage device 1, and the device for monitoring and controlling the charging and discharging states, may be an external device to the energy storage device 1.

[0038] [2. Configuration of the ventilation chamber 100 and its surroundings] Next, the configuration of the ventilation chamber 100 and its surroundings according to this embodiment will be described with reference to Figures 3 to 9, in addition to Figures 1 and 2 described above. Figure 3 is an exploded perspective view showing the configuration of the ventilation chamber 100 according to this embodiment. In Figure 3, the membrane member 200 is spaced apart from the first wall portion 110, and the third wall portion 130 is spaced apart from the side opening 140 provided in the lid 20. Figure 4 is a perspective view showing the configuration of the third wall portion 130 according to this embodiment. Figure 5 is a plan view (viewed from the negative Y-axis direction, the same applies hereinafter) showing the internal configuration of the ventilation chamber 100 according to this embodiment. Figure 6 is a plan view showing the position of the second wall portion 132 in the ventilation chamber 100 according to this embodiment. Figure 7 is a first cross-sectional view of the ventilation chamber 100 according to this embodiment. In Figure 7, the cross-section along line VII-VII in Figure 6 is shown. Figure 8 is a second cross-sectional view of the ventilation chamber 100 according to this embodiment. In Figure 8, the cross-section along line VIII-VIII in Figure 6 is shown. Figure 9 is a third cross-sectional view of the ventilation chamber 100 according to the embodiment. Figure 9 shows the cross-section along line IX-IX in Figure 6.

[0039] As shown in Figures 3 to 9, the energy storage device 1 according to this embodiment is equipped with a ventilation chamber 100 in the outer casing 10 that connects the inside and outside of the outer casing 10. The ventilation chamber 100 is formed inside a side opening 140 provided on the side of the lid 20 in the negative Y-axis direction.

[0040] Specifically, the ventilation chamber 100 comprises a first wall portion 110 with a through hole 115 connected to the interior of the exterior body 10, a membrane member 200 that closes the through hole 115, and a side wall portion 150 positioned to surround the through hole 115. The through hole 115 is a hole that penetrates the first wall portion 110 in the Y-axis direction. The Y-axis direction is an example of the first direction. In other words, when viewed from the first direction, which is the direction in which the through hole 115 penetrates, the side wall portion 150 is positioned to surround the membrane member 200. The side wall portion 150 is provided with an opening 155 that connects the interior of the ventilation chamber 100 to the exterior of the exterior body 10. "Interior of the ventilation chamber 100" refers to the space outside the first wall portion 110 (i.e., in the negative Y-axis direction) and the space surrounded by the side wall portion 150. In this embodiment, the opening 155 in the side wall portion 150 is oriented in the negative Z-axis direction, connecting the inside of the ventilation chamber 100 to the outside of the exterior body 10.

[0041] In this embodiment, the first wall portion 110 is a wall portion whose thickness direction is oriented in the Y-axis direction. The first wall portion 110 comprises a film arrangement surface 111, a second inclined surface 107, and a connecting surface 112. The film arrangement surface 111 is a surface on which through holes 115 are provided and on which the film member 200 is arranged. The second inclined surface 107 is located in the positive Y-axis direction relative to the film arrangement surface 111. The connecting surface 112 connects the film arrangement surface 111 and the second inclined surface 107. In a plan view, the film arrangement surface 111 and the second inclined surface 107 are arranged side by side in the X-axis direction. The connecting surface 112 is a surface that extends along the YZ plane to connect the film arrangement surface 111 and the second inclined surface 107, which are located at different positions in the Y-axis direction.

[0042] The membrane member 200 is bonded to the periphery of the through-hole 115 on the membrane placement surface 111 of the first wall portion 110, for example, via an adhesive layer. Examples of adhesive layer materials include acrylic adhesives and silicone adhesives. As a result, the membrane member 200 closes the through-hole 115. "Closing the through-hole 115" does not require completely blocking the flow of gas through the through-hole 115. In this embodiment, the membrane member 200 has enough permeability to achieve pressure equilibrium between the inside and outside of the outer casing 10 under normal conditions. However, the membrane member 200 does not have enough permeability to stop the rise in internal pressure of the outer casing 10 when gas is discharged from the energy storage element 50. Therefore, if the internal pressure of the outer casing 10 rises excessively, the membrane member 200 will open the through-hole 115 by peeling off or rupturing at least a portion of it from the first wall portion 110. As a result, gas inside the outer casing 10 is discharged to the outside of the outer casing 10 through the through holes 115 and openings 155. Consequently, damage to the outer casing 10 due to an increase in internal pressure is suppressed. The permeability of the membrane member 200 can be measured in accordance with the "air permeability resistance" specified in JIS P8117:2009. In other words, the smaller the air permeability resistance value, the higher the permeability, and the larger the air permeability resistance value, the lower the permeability.

[0043] More specifically, the membrane member 200 in this embodiment is a breathable waterproof membrane made of a material that is waterproof and breathable. The material used to form the membrane member 200 may be Gore-Tex® or TEMISH®, etc.

[0044] Thus, the third wall portion 130 is positioned opposite the first wall portion 110, where the membrane member 200 that closes the through hole 115 is located, in the Y-axis direction. The third wall portion 130 is a lid member that closes the side opening 140 (see Figure 3) provided in the lid 20. In other words, the third wall portion 130 can also be described as a wall portion that separates the inside of the ventilation chamber 100 from the outside of the outer casing 10 in the Y-axis direction.

[0045] More specifically, the side opening 140 is provided with a mounting groove 160 (see Figures 5 and 6) on the outer circumference of the side wall 150, and the third wall 130 is provided with an insertion wall 139 (see Figure 4) that is inserted into the mounting groove 160. For example, adhesive is contained in the mounting groove 160. Furthermore, the third wall 130 is attached to the side opening 140 by inserting the insertion wall 139 into the mounting groove 160 containing the adhesive. After the adhesive hardens, the third wall 130 is fixed to the side opening 140, and the airtightness of the joint between the third wall 130 and the side opening 140 is maintained. In other words, the internal space of the ventilation chamber 100 is substantially a closed space except for the opening 155 and the through hole 115.

[0046] The ventilation chamber 100 further includes a second wall portion 132 positioned between the opening 155 and the through hole 115. In this embodiment, the second wall portion 132 is connected to a third wall portion 130, as shown in Figure 4, and the second wall portion 132 is positioned in the location shown in Figures 6 to 8 by attaching the third wall portion 130 to the side opening 140 of the lid 20. In other words, in this embodiment, the second wall portion 132 is integrated with the third wall portion 130. The third wall portion 130 is a wall portion whose thickness direction is oriented in the Y-axis direction and which extends in the X-axis direction and the Z-axis direction. If the Y-axis direction is the first direction, one of the X-axis direction and the Z-axis direction is an example of a second direction, and the other of the X-axis direction and the Z-axis direction is an example of a third direction. The second direction is a direction that intersects with the first direction, and the third direction is a direction that intersects with the first direction and the second direction.

[0047] In this embodiment, the second wall portion 132 is positioned to form a gap G between it and the inner surface 101 of the ventilation chamber 100. Therefore, a gas flow path is ensured between the opening 155 and the through hole 115 in the ventilation chamber 100. For example, if the external pressure of the outer casing 10 (e.g., atmospheric pressure) becomes higher than the internal pressure of the outer casing 10, the outside air can flow into the inside of the outer casing 10 through the opening 155, the gap G, the membrane member 200, and the through hole 115. This equalizes the pressure inside and outside the outer casing 10. As a result, damage or deterioration of the outer casing 10 due to the magnitude of the pressure difference between the inside and outside of the outer casing 10, and / or repeated increases and decreases in the pressure difference, is suppressed.

[0048] Specifically, as shown in Figures 6 to 8, the second wall portion 132 is positioned opposite the second inclined surface 107, which is part of the inner surface 101 of the ventilation chamber 100, in the Y-axis direction. Between the edge of the second wall portion 132 in the Y-axis positive direction and the second inclined surface 107, there exists a first gap Ga, which is at least a part of the gap G. As shown in Figures 7 and 8, this first gap Ga is located in the Y-axis positive direction relative to the membrane member 200.

[0049] The ventilation chamber 100, configured in this way, has an opening 155 that opens to the outside of the outer casing 10. Therefore, in addition to gases such as air, liquids such as water can also enter the ventilation chamber 100 through the opening 155. The liquid that enters through the opening 155 may be oils such as gasoline or liquids containing chemicals such as detergents. If such liquids adhere to the membrane member 200, malfunctions such as deterioration or damage to the membrane member 200 may occur. In particular, if the liquid remains attached to the membrane member 200 for a long period of time, malfunctions are more likely to occur in the membrane member 200. For this reason, it is desirable that the membrane member 200 has high resistance to chemicals. However, the type of liquid that can enter through the opening 155 differs depending on the environment in which the energy storage device 1 is located. Consequently, there are many different types of chemicals that may adhere to the membrane member 200, and it is not practical to manufacture a membrane member 200 that is resistant to such a wide variety of chemicals. In addition, the membrane member 200 is required to have adhesion to the surface on which it is placed, as well as waterproofing and breathability, so it is not practical to design a membrane member 200 that possesses all of these various properties. Furthermore, even if it were possible to design a membrane member 200 that satisfies all of the above properties, the cost of the membrane member 200 would be considerably high, making it difficult to say that it can be applied to mass-produced products. Therefore, the problem becomes how to protect the membrane member 200 from liquids that penetrate from the outside.

[0050] To address these problems, the energy storage device 1 according to this embodiment has a second wall portion 132 positioned between the opening 155 and the through hole 115 in the ventilation chamber 100, thereby suppressing the reach of liquid entering from the opening 155 to the membrane member 200. The gas flow path between the opening 155 and the through hole 115 is secured by the gap G between the second wall portion 132 and the inner surface 101 of the ventilation chamber 100. In other words, the ventilation chamber 100 can suppress the adhesion of liquid from the outside of the outer casing 10 to the membrane member 200 without impairing its original function of moving gas from one side to the other.

[0051] More specifically, the technical features of the energy storage device 1 according to this embodiment can be described as follows, for example.

[0052] The energy storage device 1 according to this embodiment comprises an outer casing 10 and an energy storage element 50 housed inside the outer casing 10. The outer casing 10 includes a ventilation chamber 100 that connects the inside and outside of the outer casing 10. The ventilation chamber 100 comprises a first wall portion 110 with a through hole 115 that is connected to the inside of the outer casing 10 and penetrates in the Y-axis direction, a membrane member 200 that closes the through hole 115, a side wall portion 150 positioned to surround the through hole 115, and a second wall portion 132. The side wall portion 150 is provided with an opening 155 that connects the inside of the ventilation chamber 100 to the outside of the outer casing 10. The second wall portion 132 is positioned between the opening 155 and the through hole 115. The inside of the ventilation chamber 100 is located in the negative Y-axis direction relative to the first wall portion 110. A gap G is formed between the second wall portion 132 and the inner surface 101 of the ventilation chamber 100. The first gap Ga, which is at least a part of the gap G, is located in the positive Y-axis direction relative to the film member 200.

[0053] According to the energy storage device 1 configured in this manner, gas can be exchanged between the inside and outside of the outer casing 10 through the through-hole 115 provided in the ventilation chamber 100, and / or gas generated from the energy storage element 50 can be discharged to the outside of the outer casing 10. In the ventilation chamber 100, a second wall portion 132 is positioned between the opening 155 and the through-hole 115, so that liquid that has entered from the opening 155 does not reach the membrane member 200. Since there is a gap G between the second wall portion 132 and the inner surface 101 of the ventilation chamber 100, gas can be exchanged between the inside and outside of the outer casing 10 through the gap G. Furthermore, in the Y-axis direction, the position of the first gap Ga, which is at least a part of the gap G, is in the Y-axis positive direction (closer to the inside of the outer casing 10) than the membrane member 200. Therefore, even if liquid reaches the first gap Ga from the opening 155, the liquid reaching the membrane member 200 from the first gap Ga is suppressed. Therefore, deterioration or damage to the membrane member 200 due to liquid adhering to the membrane member 200 is suppressed. Thus, the energy storage device 1 according to this embodiment is an energy storage device 1 with improved reliability.

[0054] More specifically, as shown in Figures 6 and 7, the second wall portion 132 roughly divides the internal space of the ventilation chamber 100 into a first space Sa and a second space Sb. The first space Sa is the space in which the membrane member 200 is located, and the second space Sb is the space in which the membrane member 200 is not located. Furthermore, the opening 155 is provided at a position connected to the second space Sb. In other words, when the opening 155 is viewed from the opening direction (negative Z-axis direction, see Figures 5 and 6), the membrane member 200 is not located in the second space Sb, which is behind the opening 155 (positive Z-axis direction). The membrane member 200 is located in the positive X-axis direction relative to the second space Sb, more so than the second wall portion 132, which is located in the positive X-axis direction. Therefore, if liquid enters the opening 155 from the opening direction, most of it will be contained in the second space Sb where the membrane member 200 is not located. When viewing the first space Sa where the membrane member 200 is located from the second space Sb (i.e., viewed from the negative X-axis direction), as shown in Figure 8, the second wall portion 132 is formed to be the size and shape that covers the entire membrane member 200. In other words, when viewed from the negative X-axis direction, the gap G located at the periphery of the second wall portion 132 is not located in a position that overlaps with the membrane member 200. Therefore, even if the liquid contained in the second space Sb can pass through the gap G at the periphery of the second wall portion 132, it must change its direction of travel in order to reach the membrane member 200. Thus, even if liquid enters from the opening 155, its arrival at the membrane member 200 is suppressed. Furthermore, the first gap Ga can function as a part that efficiently returns the liquid that has moved beyond the second wall portion 132 to the first space Sa back to the second space Sb. This is particularly evident, for example, when the energy storage device 1 is positioned with the positive Y-axis direction facing downwards.

[0055] In the energy storage device 1 according to this embodiment, the ventilation chamber 100 includes a third wall portion 130 that faces the first wall portion 110 in the Y-axis direction. The end of the second wall portion 132 in the negative Y-axis direction is connected to the third wall portion 130.

[0056] In this way, the end of the second wall portion 132 positioned between the opening 155 and the through hole 115 in the negative Y-axis direction is connected to the third wall portion 130. Therefore, a gap G can not be formed at this end. Consequently, liquid that enters from the opening 155 is less likely to reach the membrane member 200. Since the second wall portion 132 can be provided integrally with the third wall portion 130, the number of parts of the energy storage device 1 is reduced. Furthermore, by attaching the third wall portion 130 to the exterior body 10, which does not have the third wall portion 130, using the adhesive mentioned above, the placement of the second wall portion 132 in relation to the ventilation chamber 100 is completed. In other words, the work of providing the ventilation chamber 100 in the exterior body 10 can be carried out efficiently.

[0057] In the energy storage device 1 according to this embodiment, the first gap Ga is formed between the Y-axis edge of the second wall portion 132 and the inner surface 101 of the ventilation chamber 100, and the width of the first gap Ga in the Y-axis direction increases as it approaches the opening 155 (see Figure 8).

[0058] In this way, the width of the first gap Ga increases as it approaches the opening 155, which promotes the flow of liquid that has entered the first gap Ga towards the opening 155. In other words, the liquid is less likely to remain in the first gap Ga and is more likely to move toward the opening 155. Consequently, the liquid that has entered the interior of the ventilation chamber 100 can be efficiently discharged from the opening 155. As a result, the liquid that enters from the opening 155 is less likely to reach the membrane member 200.

[0059] In the energy storage device 1 according to this embodiment, the side wall portion 150 is provided with a first inclined surface 106 facing the inside of the ventilation chamber 100. The first inclined surface 106 is inclined in a direction that moves closer to the outside of the outer casing 10 as it approaches the opening 155. Specifically, as shown in Figures 5 and 6, the first inclined surface 106 is located in the side wall portion 150 adjacent to the opening 155, in the positive X-axis direction of the opening 155, and is inclined in a direction that moves in the negative Z-axis direction as it moves in the negative X-axis direction.

[0060] With this configuration, as shown in Figure 1, when the energy storage device 1 is positioned with the opening 155 facing downwards (i.e., with the negative Z-axis direction pointing downwards), liquid that enters the ventilation chamber 100 from the opening 155 is easily discharged to the outside of the outer casing 10 by the first inclined surface 106. This makes it more difficult for liquid that enters from the opening 155 to reach the membrane member 200. More specifically, even if liquid that enters from the opening 155 goes beyond the second wall portion 132 and reaches the membrane placement surface 111, the first inclined surface 106 promotes the flow of that liquid towards the opening 155. In this embodiment, a second gap Gb, which is part of the gap G, exists between the edge of the second wall portion 132 in the negative Z-axis direction and the inner surface of the side wall portion 150. Therefore, liquid moving along the first inclined surface 106 can pass through the second gap Gb and flow out to the outside from the opening 155.

[0061] In this embodiment, the gap G further includes a third gap Gc formed between the Z-axis positive edge of the second wall portion 132 and the inner surface of the side wall portion 150. The third gap Gc functions as part of the gas flow path inside the ventilation chamber 100. The third gap Gc may also function as part of the flow path for liquid that has moved to the first space Sa in the X-axis positive direction from the second wall portion 132 to move to the second space Sb in the X-axis negative direction from the second wall portion 132. The gap G does not necessarily include the second gap Gb and the third gap Gc. In other words, a portion of the gap G does not need to exist between the second wall portion 132 and the inner surface 101 of the ventilation chamber 100 in the Z-axis direction. Even in this case, it is sufficient that there is a first gap Ga located in the Y-axis positive direction from the membrane member 200 between the second wall portion 132 and the inner surface 101 of the ventilation chamber 100. This allows for gas exchange between the inside and outside of the outer casing 10 while suppressing the reach of liquid that has entered through the opening 155 to the membrane member 200.

[0062] In the energy storage device 1 according to this embodiment, the ventilation chamber 100 includes a second inclined surface 107 positioned in the positive Y-axis direction relative to the second wall portion 132. The second inclined surface 107 is tilted in a direction that advances in the positive Y-axis direction as it approaches the opening 155.

[0063] In this configuration, when the energy storage device 1 is positioned with the positive Y-axis facing downwards, any liquid that enters the ventilation chamber 100 through the opening 155 is easily discharged to the outside of the outer casing 10 by the second inclined surface 107. As a result, it becomes more difficult for the liquid that enters through the opening 155 to reach the membrane member 200.

[0064] As shown in Figure 7, the second inclined surface 107 in this embodiment is also inclined in the direction of the positive Y-axis as it moves away from the membrane member 200 in the X-axis direction. Therefore, when the energy storage device 1 is positioned with the positive Y-axis direction facing downwards, it is difficult for liquid that has entered the second inclined surface 107 from the opening 155 to pass through the first gap Ga and proceed further in the positive X-axis direction than the second wall portion 132. As a result, it becomes more difficult for liquid that has entered from the opening 155 to reach the membrane member 200.

[0065] The above description focuses on the configuration of the ventilation chamber 100 and its surrounding area in relation to the embodiment of the energy storage device 1. However, the energy storage device 1 may also have a ventilation chamber 100 with a different configuration than that shown in Figures 2 to 9. Therefore, the following describes some modifications of the energy storage device 1, focusing on the differences from the above embodiment.

[0066] [3. Variant] Figure 10 is a cross-sectional view of a modified example of the embodiment of the ventilation chamber 100a. The position of the cross-section in Figure 10 corresponds to the position of the cross-section in Figure 8.

[0067] The modified energy storage device 1a comprises an outer casing 10 and an energy storage element 50, the outer casing 10 having a ventilation chamber 100a connecting the inside and outside of the outer casing 10. The ventilation chamber 100a comprises a first wall portion 110 having a through hole 115 penetrating in the Y-axis direction, a membrane member 200 that closes the through hole 115, a side wall portion 150 positioned to surround the through hole 115, and a second wall portion 132a. The side wall portion 150 has an opening 155, and the second wall portion 132a is positioned between the opening 155 and the through hole 115. The inside of the ventilation chamber 100a is located in the negative Y-axis direction relative to the first wall portion 110. A gap G is formed between the second wall portion 132a and the inner surface 101 of the ventilation chamber 100a. The first gap Ga, which is at least a part of the gap G, is located in the positive Y-axis direction relative to the membrane member 200. A third wall portion 130 is provided at a position opposite the first wall portion 110 in the Y-axis direction. These configurations are common to the ventilation chamber 100 according to the embodiment.

[0068] In the ventilation chamber 100a according to this modified example, the second wall portion 132a is not connected to the third wall portion 130, but is connected to the first wall portion 110. In this respect, it differs from the ventilation chamber 100 according to the embodiment. Specifically, in this modified example, the end portion of the second wall portion 132a in the Y-axis positive direction, and both ends in the Z-axis direction, are connected to the second inclined surface 107, and a first gap Ga is formed between these two ends.

[0069] Even in this case, since the position of the first gap Ga is in the positive Y-axis direction relative to the membrane member 200, even if liquid reaches the first gap Ga from the opening 155, the reach of liquid from the first gap Ga to the membrane member 200 is suppressed.

[0070] Furthermore, as shown in Figure 10, when viewed from the negative X-axis direction, the second wall portion 132a is formed to be the size and shape that covers the entire membrane member 200. In other words, when viewed from the negative X-axis direction, the gap G located at the periphery of the second wall portion 132a is not positioned to overlap with the membrane member 200. This means that even if a part of the gap G (fourth gap Gd) exists between the second wall portion 132a and the third wall portion 130, the reach of liquid that has entered from the opening 155 to the membrane member 200 is suppressed. In this modified example, a part of the gap G (fourth gap Gd) exists between the second wall portion 132a and the third wall portion 130. As a result, gas ejected from the through hole 115 in the negative Y-axis direction can more easily reach the opening 155 by passing over the negative Y-axis end of the second wall portion 132a. In other words, if the internal pressure of the outer casing 10 rises excessively, the gas inside the outer casing 10 can be discharged to the outside more efficiently.

[0071] In this modified example, it is not essential that a portion of the gap G (fourth gap Gd) is formed between the second wall portion 132a and the third wall portion 130. The second wall portion 132a may be formed to a size and shape that contacts the third wall portion 130. This makes it even more difficult for liquid that has entered the second space Sb (see Figure 6) to pass over the second wall portion 132a and reach the first space Sa (see Figure 6) where the membrane member 200 is located.

[0072] (Other embodiments) Although embodiments and variations thereof of the present invention have been described above, the present invention is not limited to the above embodiments and variations. The embodiments and variations disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims.

[0073] The membrane member 200 does not need to be a breathable waterproof membrane. For example, the membrane member 200 does not need to be breathable. Even in this case, the membrane member 200 can make it difficult for foreign matter to enter the exterior of the exterior body 10 from the outside. Furthermore, when gas is discharged from the energy storage element 50, the membrane member 200 can be discharged to the outside by peeling off or rupturing at least a part of it from the first wall portion 110 due to the rapid increase in the internal pressure of the exterior body 10. However, from the viewpoint of enabling pressure equilibrium between the inside and outside of the exterior body 10 under normal conditions, it is preferable that the membrane member 200 be breathable.

[0074] It is not essential that the second wall portion 132 be integrally provided with the third wall portion 130. If the second wall portion 132 is separate from the third wall portion 130, the second wall portion 132 may be fixed to the third wall portion 130 by methods such as adhesive bonding, welding, or fitting. If the second wall portion 132 is separate from the third wall portion 130, the second wall portion 132 may be formed from a different material than the material forming the third wall portion 130. As the material forming the second wall portion 132, metals such as iron or aluminum may be used.

[0075] The second wall portion 132 may be connected to the side wall portion 150, rather than to the third wall portion 130 or the first wall portion 110. In other words, there are no particular limitations on the part that supports the second wall portion 132, as long as it can be fixed in a predetermined position inside the ventilation chamber 100.

[0076] The width of the first gap Ga in the Y-axis direction does not need to increase as it approaches the opening 155. The width of the first gap Ga in the Y-axis direction may be constant in the Z-axis direction. Even in this case, if the energy storage device 1 is positioned with the negative Z-axis direction facing downwards, the liquid that has entered through the opening 155 and reached the first gap Ga can be moved toward the opening 155 by gravity. If the ventilation chamber 100 is equipped with a second inclined surface 107 and the energy storage device 1 is positioned with the positive Y-axis direction facing downwards, the liquid that has entered through the opening 155 and reached the first gap Ga will be encouraged to move toward the opening 155 by the second inclined surface 107.

[0077] It is not essential that the side wall portion 150 has a first inclined surface 106. The portion of the side wall portion 150 corresponding to the first inclined surface 106 may be a surface parallel to the XY plane. For example, if the energy storage device 1 is positioned with the positive Y-axis direction facing downwards, it is difficult for liquid entering through the opening 155 to pass through the second wall portion 132 and reach the membrane placement surface 111. Therefore, the portion of the side wall portion 150 corresponding to the first inclined surface 106 does not need to be inclined in a direction that approaches the outside of the outer casing 10 as it approaches the opening 155.

[0078] The first wall portion 110 does not necessarily have a second inclined surface 107. The portion of the first wall portion 110 corresponding to the second inclined surface 107 may be a flat portion parallel to the XZ plane. For example, if the energy storage device 1 is positioned with the negative Z-axis direction facing downwards, even if liquid that has entered through the opening 155 reaches the flat portion, gravity will cause the liquid to move towards the opening 155 (downward). Therefore, the portion of the first wall portion 110 corresponding to the second inclined surface 107 does not need to be inclined in a direction that moves in the positive Y-axis direction as it approaches the opening 155.

[0079] The connecting surface 112 (see Figure 7) that connects the membrane arrangement surface 111 and the second inclined surface 107 in the first wall portion 110 does not need to be parallel to the YZ plane, and may be inclined with respect to the YZ plane. The internal space of the ventilation chamber 100 is formed in a substantially rectangular shape in plan view by the side wall portion 150, but there are no particular limitations on the shape of the internal space of the ventilation chamber 100 in plan view, and it may be substantially circular, or a polygonal shape other than a rectangle.

[0080] The outer casing 10 does not need to be a roughly rectangular parallelepiped shape (box shape) as shown in Figures 1 and 2. The outer shape of the outer casing 10 may be cylindrical or spherical, etc. The size and shape of the outer casing 10 may be appropriately determined depending on the number or size of the energy storage elements 50 to be housed in the outer casing 10.

[0081] Various supplementary details regarding the energy storage device 1 according to the above embodiment may be appropriately applied to the energy storage device 1a according to the above modified example. Configurations constructed by arbitrarily combining the components included in the above embodiment and its modified examples are also within the scope of the present invention. [Industrial applicability]

[0082] This invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries. [Explanation of symbols]

[0083] 1. 1a Energy storage device 10 Exterior 50 Energy storage elements 100, 100a ventilation room 101 Inner self 106 First slope 107 Second slope 110 First wall 111 Membrane placement surface 112 Connection surface 115 Through hole 130 Third wall 132, 132a Second wall part 139 Insertion wall 140 Side opening 150 Side wall section 155 Opening 160 mounting groove 200 Membrane parts G Gap Ga First gap

Claims

1. It comprises an outer casing and an energy storage element housed inside the outer casing, The exterior body includes a ventilation chamber that connects the inside and outside of the exterior body. The aforementioned ventilation chamber is A through hole connected to the interior of the exterior body, comprising a first wall portion having a through hole that penetrates in a first direction, A membrane member that seals the through hole, A side wall portion positioned to surround the aforementioned through hole, the side wall portion having an opening that connects the inside of the ventilation chamber to the outside of the exterior body, A second wall portion is disposed between the opening and the through hole, The interior of the ventilation chamber is located in one direction relative to the first wall, A gap is formed between the second wall portion and the inner surface of the ventilation chamber. The first gap, which is at least a part of the gap, is located in the other direction of the first direction, relative to the film member. Energy storage device.

2. The ventilation chamber comprises a third wall portion facing the first wall portion in the first direction, The first end of the second wall portion is connected to the third wall portion. The energy storage device according to claim 1.

3. The first gap is formed between the first edge of the second wall portion and the inner surface, The width of the first gap in the first direction increases as it approaches the opening. The energy storage device according to claim 1 or 2.

4. The side wall portion is provided with a first inclined surface facing the interior of the ventilation chamber, The first inclined surface is tilted in a direction that moves closer to the outside of the exterior body as it approaches the opening. The energy storage device according to claim 1 or 2.

5. The ventilation chamber is provided with a second inclined surface located on the other side in the first direction relative to the second wall portion, The second inclined surface is tilted in a direction that advances toward the other side of the first direction as it approaches the opening. The energy storage device according to claim 1 or 2.

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