Power storage device

Abstract

A power storage device according to the present invention is provided with: a power storage element comprising a gas discharge valve; a spacer disposed at a position adjacent to the power storage element; and a case capable of accommodating and sealing the power storage element and the spacer. The case is provided with an exhaust part for exhausting, to the outside of the case, a gas discharged from the gas discharge valve. The exhaust part is provided with a check valve for preventing the flow of gases from the outside to the inside of the case.

Description

Power storage device

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

[0002] Conventionally, a plurality of rectangular batteries having discharge ports are arranged along a predetermined direction in a sealed container having a gas discharge duct, and the gas discharged from the discharge ports of each rectangular battery is discharged from the gas discharge duct. A battery system is known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2009-170258

[0004] In the above-described battery system, there is a risk that combustible gas or combustible emissions discharged from the rectangular battery due to thermal runaway will ignite, burn, or generate heat due to oxygen in the atmosphere flowing in from outside the battery system. As a result, the temperature inside the storage battery device rises, and there is a possibility that thermal runaway will spread and chain. An object of the present invention is to provide a power storage device capable of suppressing the spread of thermal runaway of a power storage element.

[0005] A power storage device according to an aspect of the present invention includes a power storage element provided with a gas discharge valve, a spacer disposed at a position adjacent to the power storage element, and a case that can accommodate and seal the power storage element and the spacer. The case includes an exhaust portion that exhausts the gas discharged from the gas discharge valve to the outside of the case, and the exhaust portion includes a check valve that prevents the flow of gas from the outside to the inside of the case.

[0006] According to the present invention, since the inflow of oxygen from the outside can be suppressed inside the power storage device, the spread of thermal runaway of the power storage element can be suppressed.

[0007] Figure 1 is a perspective view showing the external appearance of an energy storage device according to an embodiment. Figure 2 is an exploded perspective view showing the components when the energy storage device according to an embodiment is disassembled. Figure 3 is a cross-sectional view showing the schematic configuration of the exhaust section according to an embodiment. Figure 4 is a perspective view showing the external appearance of an energy storage element according to an embodiment. Figure 5 is a perspective view showing the external appearance of a spacer according to an embodiment. Figure 6 is an explanatory diagram showing the gas discharge valve of each energy storage element and the discharge valve of each spacer according to an embodiment. Figure 7 is a block diagram showing the control configuration of an energy storage device according to the third method. Figure 8 is a block diagram showing the control configuration of an energy storage device according to the fourth method. Figure 9 is a block diagram showing the control configuration of an energy storage device according to the fifth method. Figure 10 is a block diagram showing the control configuration of an energy storage device according to the sixth method. Figure 11 is an exploded perspective view showing an energy storage device according to Modification 1. Figure 12 is a perspective view showing an energy storage element according to Modification 1. Figure 13 is an explanatory diagram showing the gas discharge valve of each energy storage element and the discharge valve of each spacer according to Modification 1. Figure 14 is a perspective view showing an energy storage element according to Modification 2. Figure 15 is an explanatory diagram showing the gas discharge valves for each energy storage element and the discharge valves for each spacer according to Modified Example 2.

[0008] (1) An energy storage device according to one aspect of the present invention comprises an energy storage element equipped with a gas discharge valve, a spacer positioned adjacent to the energy storage element, and a case capable of housing and sealing the energy storage element and the spacer, wherein the case is equipped with an exhaust section for exhausting the gas discharged from the gas discharge valve to the outside of the case, and the exhaust section is equipped with a check valve to prevent the flow of gas from the outside to the inside of the case.

[0009] According to the energy storage device described in (1), even if the gas pressure inside the energy storage element increases due to thermal runaway or the like, causing the gas discharge valve to open and gas to be discharged into the case, the gas can be discharged outside the case through the exhaust section. Since a check valve is provided in the exhaust section, the inflow of oxygen from outside the case can be suppressed, and combustion by oxygen in the atmosphere can be suppressed. Therefore, the expansion of thermal runaway in the energy storage element can be suppressed.

[0010] (2) In the energy storage device described in (1) above, the spacer may comprise a spacer body, an inert gas contained within the spacer body, and a discharge valve provided in the spacer body that releases the inert gas when opened.

[0011] According to the energy storage device described in (2), an inert gas (nitrogen, carbon dioxide, argon, etc.) can be released from the discharge valve. This inert gas allows flammable gases released from the energy storage element to be discharged from the exhaust section, thereby improving the safety of the energy storage device.

[0012] (3) In the energy storage device described in (1) above, the spacer may comprise a spacer body, a fire extinguishing agent enclosed within the spacer body, and a discharge valve provided on the spacer body that releases the fire extinguishing agent when opened.

[0013] According to the energy storage device described in (3), a fire extinguishing agent can be released from the discharge valve. This fire extinguishing agent can extinguish flames generated by flammable gases released from the energy storage element, thus improving the safety of the energy storage device.

[0014] (4) In the energy storage device described in (2) or (3) above, the discharge valve may be opened in conjunction with the opening of the gas discharge valve.

[0015] According to the energy storage device described in (4), the spacer's discharge valve opens in conjunction with the opening of the gas discharge valve, so when gas is discharged from the gas discharge valve, an inert gas or fire extinguishing agent is discharged from the discharge valve. This allows the gas discharged from the gas discharge valve to be exposed to an inert gas or fire extinguishing agent at an appropriate timing.

[0016] (5) The energy storage device described in (4) above may also include an opening sensor for detecting the opening of the gas discharge valve, and an opening unit for opening the discharge valve based on the fact that the opening sensor has detected the opening of the gas discharge valve.

[0017] According to the energy storage device described in (5), the valve opening unit opens the discharge valve based on the valve opening sensor detecting the opening of the gas discharge valve. Therefore, even if a malfunction occurs in the operation of the discharge valve itself that prevents it from opening, the valve opening unit can open the discharge valve. Thus, the stability of opening the non-discharge valve can be improved.

[0018] (6) In the energy storage device described in any one of (2) to (5) above, an exhaust passage for the gas discharged from the gas discharge valve may be provided, and the discharge valve may be positioned opposite the exhaust passage.

[0019] According to the energy storage device described in (6), since the discharge valve is positioned opposite the exhaust passage, the gas passing through the exhaust passage is reliably exposed to the inert gas or fire extinguishing agent from the discharge valve. Therefore, the ignition suppression effect on the gas can be enhanced.

[0020] (7) In the energy storage device described in any one of (2) to (6) above, the energy storage element comprises an electrode body and a container housing the electrode body, wherein the container has a shape based on a rectangular parallelepiped, and at least one corner of the rectangular parallelepiped is a first notch formed in the shape of a notch that penetrates the container, and in the spacer body, a second notch is formed in the part opposite to the first notch that penetrates the spacer body, the gas discharge valve is arranged in the first notch, and the discharge valve is arranged in the second notch.

[0021] According to the energy storage device described in (7), the first notch of the energy storage element container and the second notch of the spacer body face each other, and a gas discharge valve is formed in the first notch, so the space formed by the first notch and the second notch can be used as an exhaust passage. Therefore, the energy storage element, spacer, and exhaust passage can be made compact.

[0022] Furthermore, since the discharge valve is located in the second notch, the gas flowing through the exhaust passage is reliably exposed to inert gas or fire extinguishing agent from the discharge valve. Therefore, the ignition suppression effect on the gas can be enhanced.

[0023] (8) In the energy storage device described in (3) above, the fire extinguishing agent may be a foam fire extinguishing agent.

[0024] (8) According to the energy storage device described above, since the fire extinguishing agent is a foam fire extinguishing agent, the foam fire extinguishing agent released from the discharge valve foams up, covering the gas or fire and enhancing the ignition suppression effect or fire extinguishing effect through a suffocation effect.

[0025] (Embodiments) Hereinafter, with reference to the drawings, an energy storage device and an energy storage element according to embodiments (including modified versions thereof) of the present invention will be described. Note that the embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection configurations of the 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. The names of each component (each element) in these embodiments are those of these embodiments and may differ from the names of each component (each element) in the background art.

[0026] In the following description and drawings, the longitudinal direction of the energy storage element and the direction along the winding axis of the electrode body provided on the energy storage element are defined as the X-axis direction. The direction in which multiple energy storage elements are arranged and the thickness direction of the container of the energy storage element are defined as the Y-axis direction. The direction in which the case lid and case body of the energy storage device are arranged, the direction in which the top and bottom surfaces of the container are arranged, or the vertical direction are defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the usage, the Z-axis direction may not be the vertical direction, but for the sake of explanation below, the Z-axis direction will be described as the vertical direction. In the following description, when "insulation" is used, it means "electrical insulation". The volume resistivity of an insulating material is 1 × 10⁻⁶ ６ Preferably Ωm or more, 1 × 10 ７ Ωm or greater is more preferable, 1 × 10 １０ A value of Ωm or greater is even more preferable.

[0027] Furthermore, in the following description, the term "sealed" refers to a function that prevents the inflow and outflow of gas due to leakage, and it is preferable that the gas inflow or outflow from inside or outside the system is 100 ml / min or less.

[0028] In the following explanation, for example, 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. The same applies to the Y-axis and Z-axis directions. Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. For example, two directions being orthogonal does not only mean that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, that is, they may include a difference of, for example, a few percent.

[0029] [Energy Storage Device] First, the general configuration of the energy storage device 1 in this embodiment will be described. Figure 1 is a perspective view showing the external appearance of the energy storage device 1 according to this embodiment. Figure 2 is an exploded perspective view showing each component when the energy storage device 1 according to this embodiment is disassembled.

[0030] The energy storage device 1 is a device that can charge electricity from an external source and discharge electricity to the outside, and in this embodiment, it has a substantially rectangular parallelepiped shape. Here, a rectangular parallelepiped refers to a hexahedron in which all faces are 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), aircraft, 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. Furthermore, the energy storage device 1 can also be used as a stationary battery for household or commercial use.

[0031] As shown in Figure 1, the energy storage device 1 includes a case 2. As shown in Figure 2, the case 2 houses a plurality of energy storage elements 10, a plurality of spacers 20, and a plurality of busbars (not shown). The energy storage device 1 also includes external terminals (positive external terminal and negative external terminal) for electrically connecting to an external device in the case 2, but their illustration and description are omitted. In addition to the above components, the energy storage device 1 may also include restraining members (end plates, side plates, etc.) for restraining the plurality of energy storage elements 10, busbar holders for holding the busbars, busbar covers, a circuit board for monitoring or controlling the charging and discharging states of the energy storage elements 10, relays, fuses, shunt resistors, connectors, and other electrical components.

[0032] Case 2 is a roughly rectangular parallelepiped (box-shaped) container (module case) that constitutes the outer casing (housing, shell) of the energy storage device 1. Case 2 is positioned outside the plurality of energy storage elements 10 and the plurality of spacers 20, etc., and fixes the plurality of energy storage elements 10 and the plurality of spacers 20, etc. in predetermined positions and protects them from impacts, etc. Case 2 is a metal case formed from a metal component such as aluminum, aluminum alloy, stainless steel, iron, plated steel sheet, etc. Case 2 may also be formed from an insulating component such as any resin material that can be used for the spacers 20 described later. If Case 2 is formed from a conductive material, the inner surface of Case 2 may be covered with an insulating material to ensure insulation from the energy storage elements.

[0033] As shown in Figure 2, Case 2 comprises a case body 30 that constitutes the main body of Case 2 and a case cover 40 that constitutes the cover of Case 2. The case body 30 is a bottomed rectangular cylindrical housing (enclosure) with an opening 31 formed in the Z-axis positive direction, and houses a plurality of energy storage elements 10 and a plurality of spacers 20, etc.

[0034] Specifically, the case body 30 has a bottom wall 32 and side walls 33. The bottom wall 32 is a flat, rectangular portion located at the end of the case body 30 in the negative Z-axis direction. The side wall 33 is a rectangular annular wall extending from the outer edge in the positive Z-axis direction and is continuously provided around the entire circumference of the bottom wall 32. The inside of the side wall 33 is an opening 31. A pair of exhaust sections 37 are provided in the portion of the side wall 33 in the negative Z-axis direction. Of the pair of exhaust sections 37, one is located at the corners in the negative Z-axis direction and the negative X-axis direction, and the other is located at the corners in the negative Z-axis direction and the positive X-axis direction. Each exhaust section 37 is a portion that connects the inside and outside of the case 2 and exhausts the gas discharged from each energy storage element 10 to the outside of the case 2.

[0035] Figure 3 is a cross-sectional view showing the schematic configuration of the exhaust section 37 according to the embodiment. Figure 3(a) shows the exhaust section 37 in a closed state, and Figure 3(b) shows the exhaust section 37 in an open state. As shown in Figure 3, the exhaust section 37 is a cylindrical duct, and a check valve 38 is provided inside it. The check valve 38 prevents the flow of gas from the outside to the inside of the case 2. The check valve 38 comprises a valve body 381 with its upper end as the axis of rotation, and a maintenance projection 382 that protrudes from the inner circumferential surface of the exhaust section 37 in order to maintain the closed state of the valve body 381. Under normal conditions, as shown in Figure 3(a), the valve body 381 contacts the maintenance projection 382 by its own weight, closing the inside of the exhaust section 37. As a result, outside air cannot enter the case 2.

[0036] When the gas discharge valve 160 (described later) of the energy storage element 10 opens and gas is discharged, the valve body 381 is pushed by the gas and rotates, opening the exhaust section 37 (see Figure 3(b)). The structure of the check valve 38 can be anything as long as it allows the flow of gas from the inside to the outside of the case 2 and prevents the flow of gas from the outside to the inside of the case 2. The check valve 38 may be a check valve using a spring, film, etc. In this embodiment, the case where the exhaust section 37 is a duct is illustrated, but the exhaust section 37 may be an opening provided in the side wall 33. In this case, it is sufficient that the check valve 38 is placed inside the opening. In addition, multiple check valves 38 may be provided in the exhaust passage S1.

[0037] The case lid 40 is a flat, rectangular member that closes the rectangular opening 31 of the case body 30. The case body 30 and the case lid 40 are sealed by joining them together by welding, welding, screwing, etc. The case body 30 and the case lid 40 may be made of the same material or of different materials.

[0038] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 has a shape in which the length in the X-axis direction is longer than the length in the Y-axis direction, specifically, a rectangular parallelepiped shape (square, prism) that is flattened in the Y-axis direction. In this embodiment, eight energy storage elements 10 are arranged in line in the Y-axis direction. The size of the energy storage elements 10 and the number of energy storage elements 10 arranged are not particularly limited, and only one energy storage element 10 may be arranged. Each energy storage element 10 may be covered with an insulating film. Details of the energy storage elements 10 will be described later.

[0039] The spacer 20 is a flattened member in the Y-axis direction that is positioned alongside the energy storage element 10 in the Y-axis direction and insulates the energy storage element 10 from other members. The spacer 20 is positioned adjacent to the energy storage element 10 in the positive or negative Y-axis direction of the energy storage element 10 and is a member that insulates and / or heats the energy storage elements 10 from each other or from the energy storage elements 10 to the case 2.

[0040] Of the spacers 20, the spacers 20 placed between adjacent energy storage elements 10 are intermediate spacers, and the two spacers 20 placed at the Y-axis ends of the multiple energy storage elements 10 are end spacers. All spacers 20 may be made of the same material, or any of the spacers 20 may be made of different materials. Not all spacers 20 need to have the function of releasing the inert gas or fire extinguishing agent of this disclosure; the effect can be expected by giving this function to at least one spacer 20. The spacers 20 will be described in detail later.

[0041] The bus bar is connected (joined) to the electrode terminals 300 of the plurality of power storage elements 10. Specifically, the plurality of bus bars connect the electrode terminals 300 of the plurality of power storage elements 10 to each other and electrically connect the electrode terminals 300 of the power storage elements 10 at the ends to the external terminals. The connection form of the bus bar is not particularly limited, and the plurality of power storage elements 10 may be connected in series in any combination, may be connected in parallel, or all the power storage elements 10 may be connected in series or in parallel. The bus bar and the electrode terminal 300 are connected (joined) by welding or the like, but the connection form is not particularly limited. The bus bar is formed of a metallic conductive member such as aluminum, an aluminum alloy, copper, a copper alloy, nickel, or a combination thereof, or a conductive member other than a metal.

[0042] [Power Storage Element] A general description of the power storage element 10 in the embodiment will be given with reference to FIG. 4. FIG. 4 is a perspective view showing the appearance of the power storage element 10 according to the embodiment.

[0043] The power storage element 10 is a power storage element that can charge electricity from the outside and discharge electricity to the outside. In the present embodiment, it has a substantially rectangular parallelepiped shape. The power storage element 10 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The power storage element 10 may be a primary battery instead of a secondary battery. Further, the power storage element 10 may be an all-solid-state lithium battery using a solid electrolyte, or may be a polymer lithium battery. Also, the power storage element 10 may be a pouch-type power storage element. In the present embodiment, a power storage element 10 having a flat rectangular parallelepiped shape (substantially rectangular parallelepiped shape) is illustrated, but the shape of the power storage element 10, that is, the shape of the container 100 is not limited to a shape based on a rectangular parallelepiped shape, and may be a shape based on a polygonal prism shape, a long cylindrical shape, an elliptical cylindrical shape, a cylindrical shape, or the like other than a rectangular parallelepiped.

[0044] As shown in FIG. 4, the energy storage element 10 includes a container 100, a pair of electrode terminals 300, and a pair of external gaskets 400. Inside the container 100, although not shown, a pair of internal gaskets, a pair of current collectors, and an electrode body are accommodated. Specifically, on the first side surface portion 110 in the +X-axis direction of the container 100, each member of the positive electrode (such as the electrode terminal 300, the external gasket 400, the internal gasket, and the current collector; the same applies hereinafter) is arranged. That is, the first side surface portion 110 is the range where each member of the positive electrode is arranged from the end surface in the +X-axis direction of the container 100. The first side surface portion 110 is a portion within the range of 1% to 10% of the length of the container 100 from the end surface in the +X-axis direction of the container 100 in the X-axis direction.

[0045] On the second side surface portion 120 in the -X-axis direction of the container 100, each member of the negative electrode is arranged. That is, the second side surface portion 120 is the range where each member of the negative electrode is arranged from the end surface in the -X-axis direction of the container  100. The second side surface portion 120 is a portion within the range of 1% to 10% of the length of the container 100 from the end surface in the -X-axis direction of the container 100 in the X-axis direction.

[0046] An electrolytic solution (non-aqueous electrolyte) is enclosed inside the container 100, but the illustration is omitted. The type of the electrolytic solution is not particularly limited as long as it does not impair the performance of the energy storage element 10, and various types can be selected. In addition to the above components, spacers arranged on the side, above, or below the electrode body, insulating films that wrap the electrode body, etc. may be arranged.

[0047] Container 100 is a case in which the outer shape is based on a rectangular parallelepiped shape that is elongated and flattened in the X-axis direction (a roughly rectangular parallelepiped shape). The length of container 100 in the X-axis direction is more than three times the length in the Z-axis direction. In Figure 4, the standard rectangular parallelepiped shape is illustrated by the dashed line L1. Specifically, container 100 has an outer shape that is elongated and flattened in the X-axis direction, with rectangular notches formed at the upper and lower ends of both ends in the X-axis direction. Each notch penetrates container 100 in the Y-axis direction. Thus, container 100 is a shape based on a rectangular parallelepiped, and all corners of the rectangular parallelepiped are notches formed that penetrate container 100. Each notch can also be said to form a recess when viewed from the standard rectangular parallelepiped shape. Of the multiple first recesses, a pair of first recesses located at the top of the container 100 each form a first recess 101, and a pair of first recesses located at the bottom of the container 100 each form a second recess 102. In other words, the first recess 101 and the second recess 102 are formed at different positions in the Z-axis direction on the first side portion 110 and the second side portion 120 of the container 100, respectively, so as to face each other in the Z-axis direction. An electrode terminal 300 is located in the first recess 101, and a gas discharge valve 160 is located in the second recess 102. The gas discharge valve 160 is located on the surface of the second recess 102 facing the X-axis direction. The gas discharge valve 160 is a safety valve that releases pressure when the pressure inside the container 100 rises excessively.

[0048] In this container 100, the two opposing end faces in the Y-axis direction are each long side faces 130. Each long side face 130 is a plane parallel to the XZ plane and elongated in the X-axis direction, and its ends in the X-axis direction have shapes corresponding to the first side face 110 and the second side face 120. Of the two opposing end faces in the Z-axis direction in the container 100, the end face in the Z-axis positive direction is the top surface 140, and the end face in the Z-axis negative direction is the bottom surface 150. The top surface 140 and the bottom surface 150 are both planes parallel to the XY plane and elongated in the X-axis direction.

[0049] The material of the container 100 is not particularly limited, but it is preferably a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet. Although not shown in the illustration, the container 100 has a liquid injection section. The liquid injection section is a part for injecting electrolyte into the inside of the container 100 during the manufacturing of the energy storage element 10.

[0050] The electrode terminals 300 are electrically connected to the electrode body via a current collector (positive terminal and negative terminal). In other words, the electrode terminals 300 are metal components that lead the electricity stored in the electrode body to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode body. The material of the electrode terminals is not particularly limited, but the electrode terminals 300 are formed from conductive materials such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminals 300 are connected (joined) to the current collector by crimping, welding, or the like, and are attached to the container 100.

[0051] The current collectors are current collectors (positive electrode current collector and negative electrode current collector) that are electrically conductive and are arranged one on each side of the electrode body in the X-axis direction, connected (joined) to the electrode body and the electrode terminals, thereby electrically connecting the electrode body and the electrode terminals.

[0052] The external gasket 400 is a plate-shaped, rectangular insulating sealing member that is placed between the container 100 and the electrode terminal 300 to insulate and seal the space between the container 100 and the electrode terminal 300. The internal gasket is a plate-shaped, rectangular insulating sealing member that is placed between the container 100 and the current collector to insulate and seal the space between the container and the current collector. The external gasket 400 and the internal gasket are made of electrically insulating resins such as 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), ABS resin, or composite materials thereof.

[0053] The electrode body is an energy storage element (power generation element) that can store electricity, formed by winding electrode plates. The electrode body has a long shape extending in the X-axis direction and has an oval shape when viewed from the X-axis direction. The length of the electrode body in the X-axis direction is at least three times the length in the Z-axis direction. Here, a wound-type electrode body is given as an example, but the shape of the electrode body is not limited to the wound type, and may also be a stacked type formed by stacking flat electrode plates, or a shape in which the electrode plates and / or separators are folded in an accordion shape (a form in which the separator is folded in an accordion shape and a rectangular electrode plate is sandwiched between them, a form in which the electrode plates and separators are stacked and then folded in an accordion shape, etc.). In any case, the stacking direction of the electrode body may be in the Y-axis direction. A bipolar type electrode body may also be used.

[0054] [Spacer] Using Figure 5, we will explain the case in which all spacers 20 are provided with the function of releasing the inert gas or fire extinguishing agent of this disclosure. Figure 5 is a perspective view showing the appearance of a spacer 20 according to an embodiment. The spacer 20 comprises a spacer body 21 and an inner body 22 enclosed within the spacer body 21.

[0055] The spacer body 21 is a box-shaped body with an outer shape based on a rectangular parallelepiped that is elongated and flattened in the X-axis direction (approximately rectangular parallelepiped shape). The spacer body 21 has a shape that corresponds to the container 100 of the energy storage element 10 when viewed in the Y-axis direction. Specifically, the spacer body 21 has an outer shape that is elongated and flattened in the X-axis direction, with rectangular second notches 212 formed at the upper and lower ends of both ends in the X-axis direction. Each second notch 212 penetrates the spacer body 21 in the Y-axis direction. Thus, the spacer body 21 has a shape based on a rectangular parallelepiped, and all corners of the rectangular parallelepiped are second notches 212 formed in the shape of notches that penetrate the spacer body 21. Of the multiple second notches 212, the release valve 213 is arranged in the second notch 212 corresponding to the second recess 102 where the gas discharge valve 160 of the energy storage element 10 is located.

[0056] Figure 6 is an explanatory diagram showing the gas discharge valve 160 of each energy storage element 10 and the discharge valve 213 of each spacer 20 according to the embodiment. Here, the ends of each energy storage element 10 and each spacer 20 in the positive X-axis direction are shown as examples, but the same applies to the ends in the negative X-axis direction.

[0057] In each energy storage element 10, the second recess 102 and the second notch 212 in the negative Z-axis direction in the spacer 20 form a continuous space in the Y-axis direction. This space is the exhaust passage S1 for the gas discharged from the gas discharge valve 160 of each energy storage element 10. The exhaust passage S1 is connected to the exhaust port 37 of the case 2. In other words, the gas discharged from the gas discharge valve 160 of each energy storage element 10 is released to the outside of the case 2 through the exhaust passage S1 and the exhaust port 37.

[0058] Each spacer 20's discharge valve 213 is positioned adjacent to the gas discharge valve 160 of the adjacent energy storage element 10 in the Y-axis direction. Since each discharge valve 213 faces the exhaust passage S1, the gas passing through the exhaust passage S1 is reliably exposed to the enclosed material 22 ejected from the discharge valve 213.

[0059] The spacer body 21 is formed in a box shape from a metal material such as stainless steel, aluminum, aluminum alloy, iron, or plated steel, and its surface is coated with an insulating material. This allows the spacer 20 to insulate the energy storage element 10 from other components.

[0060] The internal container 22 contains at least one of an inert gas and a fire extinguishing agent. In other words, the internal container 22 may contain only one of the inert gas and / or the fire extinguishing agent, or it may contain both. The inert gas is contained under high pressure within the spacer body 21 and is ejected from the discharge valve 213 when the discharge valve 213 is opened. Any inert gas that can be ejected from the discharge valve 213 after it is opened may be used as the inert gas. Generally, nitrogen gas and carbon dioxide gas are preferred from a cost standpoint. In addition to holding the inert gas under high pressure, the inert gas (nitrogen gas, carbon dioxide gas, etc.) may be generated on-site using a chemical reaction and then released.

[0061] The fire extinguishing agent is contained under high pressure within the spacer body 21 and is ejected from the discharge valve 213 when the discharge valve 213 is opened. Any fire extinguishing agent that can be ejected from the discharge valve 213 after it is opened may be used. Examples of fire extinguishing agents include powder fire extinguishing agents, liquid fire extinguishing agents, and foam fire extinguishing agents, but foam fire extinguishing agents are preferred. Any foam fire extinguishing agent specified in Article 21-2, Paragraph 2 of the Fire Service Act may be used, but synthetic surfactant foam fire extinguishing agents and aqueous film foam fire extinguishing agents are preferred. The spacer body 21 may also have a built-in ejection device for ejecting the fire extinguishing agent from the opened discharge valve 213. In particular, if the fire extinguishing agent is a foam fire extinguishing agent, the ejection device may be equipped with a mechanism to assist in ejecting the foam fire extinguishing agent in a foamy form.

[0062] In the case of liquid fire extinguishing agents, it is preferable that they contain a flame retardant. The flame retardant includes at least one of acyclic fluorinated ethers, fluorinated phosphate esters, and phosphazene derivatives. These exhibit high flame retardancy upon vaporization.

[0063] [Opening the Discharge Valve] Next, we will explain how to open the discharge valve 213. The discharge valve 213 should open in conjunction with the opening of the gas discharge valve 160. Here, "the discharge valve 213 opens in conjunction with the opening of the gas discharge valve 160" includes a first timing, a second timing, and a third timing. The first timing is when the discharge valve 213 opens immediately after the opening of the gas discharge valve 160. The second timing is when the discharge valve 213 opens at the same time as the opening of the gas discharge valve 160. The third timing is when the discharge valve 213 opens immediately before the opening of the gas discharge valve 160. In this way, multiple methods can be used to open the discharge valve 213 in conjunction with the opening of the gas discharge valve 160, so we will explain each method here. Each method may be used individually or in combination.

[0064] <First Method> The first method involves opening the discharge valve 213 with high-temperature gas discharged from the opened gas discharge valve 160. Specifically, the discharge valve 213 is made of a material that melts at a temperature below the gas temperature, and melts and opens when exposed to the gas. This case is included in the first timing.

[0065] <Second Method> The second method is one in which the gas discharge valve 160 opens due to the expansion of the energy storage element 10. Immediately before the gas discharge valve 160 opens, the energy storage element 10 is expanding. The spacer 20 receives this expansion, so the internal pressure of the spacer 20 increases. The discharge valve 213 is formed to open when the internal pressure of the spacer 20 exceeds a predetermined value. In other words, when the energy storage element 10 expands until just before the gas discharge valve 160 opens, the internal pressure of the spacer 20 exceeds the predetermined value due to this expansion, and the discharge valve 213 opens. In this case, it is included in the second timing or the third timing.

[0066] <Third Method> The third method is one in which the gas discharge valve 160 opens due to the pressure inside case 2. When case 2 is sealed, the gas discharge valve 160 opens, causing high pressure inside case 2. When the internal pressure inside case 2 exceeds a first predetermined value, the discharge valve 213 is configured to open. In other words, if the internal pressure of case 2 exceeds the first predetermined value immediately after the gas discharge valve 160 opens, the discharge valve 213 opens and the internal body 22 is released. This case is included in the first timing. At this time, a valve is also provided at the exhaust port 37 of case 2, and if the internal pressure of case 2 exceeds a second predetermined value which is greater than the first predetermined value, this valve may be opened and exhaust may occur.

[0067] The valve at the exhaust port 37 may be a solenoid valve. Figure 7 is a block diagram showing the control configuration of the third type of energy storage device 1. As shown in Figure 7, the energy storage device 1 includes a solenoid valve 371 at the exhaust port 37, a control unit 50 provided on a circuit board to control the solenoid valve 371, and a pressure sensor 56 for detecting the internal pressure of the case 2. The control unit 50 is a microcontroller, and when the internal pressure detected by the pressure sensor 51 exceeds a second predetermined value, it opens the solenoid valve 371 to release the sealed state of the case 2 and exhaust the gas.

[0068] <Fourth Method> The fourth method is a method in which the discharge valve 213 is opened by the valve opening unit 55 based on the opening of the gas discharge valve 160. Figure 8 is a block diagram showing the control configuration of the energy storage device 1 according to the fourth method. As shown in Figure 8, the energy storage device 1 includes a valve opening unit 55 that opens the discharge valve 213, a valve opening sensor 56 that detects the opening of the gas discharge valve 160, and a control unit 50.

[0069] The valve opening section 55 is a mechanism that opens each discharge valve 213 by individually applying a physical impact to cause it to rupture. The valve opening section 55 may be the discharge valve 213 itself, which is made up of solenoid valves.

[0070] The valve opening sensor 56 can be any sensor that detects the opening of the gas discharge valve 160. Examples of valve opening sensors 56 include image sensors and temperature sensors. In the case of an image sensor, the gas discharge valve 160 is imaged, and the opening is detected by performing image processing on the captured image. In the case of a temperature sensor, the temperature inside the case 2 is detected, and when the temperature rises above a certain temperature, it is detected that the gas discharge valve 160 has opened.

[0071] When the valve opening sensor 56 detects that the gas discharge valve 160 has opened, the control unit 55 controls the valve opening unit 55 to open each discharge valve 213. This is included in the first timing.

[0072] <Fifth Method> The fifth method is a method in which the valve opening unit 55 opens the discharge valve 213 based on the temperature of the energy storage element 10. Figure 9 is a block diagram showing the control configuration of the energy storage device 1 according to the fifth method. As shown in Figure 9, the energy storage device 1 includes a plurality of temperature sensors 58 that detect the temperature of each energy storage element 10, a valve opening unit 55, and a control unit 50. Each temperature sensor 58 is arranged one-to-one with each energy storage element 10 and detects the temperature of each energy storage element 10. The control unit 50 controls the valve opening unit 55 to open the discharge valve 213 when the detection result of each temperature sensor 58 reaches the temperature just before the gas discharge valve 160 of each energy storage element 10 opens. In this case, it is included in the second timing or the third timing.

[0073] <Sixth Method> The sixth method is a method in which the valve opening unit 55 opens the discharge valve 213 based on the pressure of the energy storage element 10. Figure 10 is a block diagram showing the control configuration of the energy storage device 1 according to the sixth method. As shown in Figure 10, the energy storage device 1 includes a plurality of pressure sensors 59 that detect the pressure of each energy storage element 10, a valve opening unit 55, and a control unit 50. Each pressure sensor 59 is arranged one-to-one with each energy storage element 10 and detects the pressure of each energy storage element 10. The control unit 50 controls the valve opening unit 55 to open the discharge valve 213 when the detection result of each pressure sensor 59 reaches the pressure just before the gas discharge valve 160 of each energy storage element 10 opens. In this case, it is included in the second timing or the third timing.

[0074] <Seventh Method> The seventh method is one in which the heat from the energy storage element 10 causes the inside of the spacer 20 to become hot and high pressure, and this pressure opens the release valve 213. The release valve 213 is formed to open when the internal pressure of the spacer 20 exceeds a predetermined value. In other words, the heat from the energy storage element 10 causes the inside of the spacer 20 to become hot and high pressure, and when the internal pressure of the spacer 20 exceeds a predetermined value, the release valve 213 opens. In this case, it is included in the second timing or the third timing. From the viewpoint of promoting high pressure inside the spacer 20, it is preferable to keep the internal volume of the spacer body 21 small. Specifically, it is preferable to keep the thickness (length in the Y-axis direction) of the spacer body 21 smaller than the thickness of the energy storage element 10.

[0075] In this embodiment, an example is given in which at least one of the inert gas and the fire extinguishing agent is contained within the spacer 20 inside the case 2. However, the disclosure is not limited thereto. A storage unit for the inert gas or fire extinguishing agent may be provided outside the case 2, and in the event of a malfunction in the energy storage element 10 inside the case 2, the inert gas or fire extinguishing agent may be introduced into the case 2 from the storage unit.

[0076] [Effects] As described above, according to the embodiment of the present invention, even when the gas pressure inside the energy storage element 10 increases and the gas discharge valve 160 opens, causing gas to be discharged into the case 2, the gas can be discharged outside the case 2 through the exhaust section 37. Since the exhaust section 37 is provided with a check valve 38, the inflow of oxygen from outside the case 2 can be suppressed, and combustion by oxygen in the atmosphere can be suppressed. Therefore, the expansion of thermal runaway of the energy storage element 10 can be suppressed.

[0077] Since the discharge valve 213 of the spacer 20 opens in conjunction with the opening of the gas discharge valve 160, when gas is discharged from the gas discharge valve 160, an inert gas (nitrogen, carbon dioxide, argon, etc.) can be discharged from the discharge valve 213. This inert gas allows the flammable gas released from the energy storage element 10 to be discharged from the exhaust section 37, thereby improving the safety of the energy storage device 1.

[0078] Since the discharge valve 213 of the spacer 20 opens in conjunction with the opening of the gas discharge valve 160, when gas is discharged from the gas discharge valve 160, the fire extinguishing agent can be released from the discharge valve 213. This allows the fire extinguishing agent to suppress gas ignition. Even if the gas were to ignite, it could be extinguished by the fire extinguishing agent.

[0079] Based on the detection by the valve opening sensor 56 that the gas discharge valve 160 is open, the valve opening unit 55 opens the discharge valve 213. Therefore, even if a malfunction occurs in the discharge valve 213 itself that prevents it from opening, the valve opening unit 55 can still open the discharge valve 213. Thus, the stability of the discharge valve 213's opening can be improved.

[0080] Since the discharge valve 213 is positioned opposite the exhaust passage S1, the gas passing through the exhaust passage S1 is reliably exposed to the internal element 22 from the discharge valve 213. Therefore, the ignition suppression effect on the gas can be enhanced. Even if the gas ignites in the exhaust passage S1, the flame will also be exposed to the inert gas or extinguishing agent, thus enhancing the fire extinguishing effect.

[0081] The second recess 102 (second notch) of the container 100 of the energy storage element 10 and the second notch 212 of the spacer body 21 face each other, and a gas discharge valve 160 is formed in the second recess 102. Therefore, the space formed by the second recess 102 and the second notch 212 can be used as an exhaust passage S1. Consequently, the energy storage element 10, the spacer 20, and the exhaust passage S1 can be made compact.

[0082] Furthermore, since the discharge valve 213 is located in the second notch 212, the gas flowing through the exhaust passage S1 is reliably exposed to the internal body 22 from the discharge valve 213. Therefore, the ignition suppression effect on the gas can be enhanced. Even if the gas were to ignite in the exhaust passage S1, the flame would also be exposed to the internal body 22, thus enhancing the fire extinguishing effect.

[0083] In particular, in this embodiment, since the gas discharge valve 160 and the discharge valve 213 are arranged adjacent to each other in the Y-axis direction, the gas discharged from the gas discharge valve 160 can be reliably exposed to the enclosed material 22 discharged from the discharge valve 213. Therefore, the ignition suppression effect and fire extinguishing effect of the enclosed material 22 can be enhanced.

[0084] Since the fire extinguishing agent is a foam fire extinguishing agent, the foam fire extinguishing agent released from the discharge valve 213 foams up, which can cover the gas or fire and enhance the ignition suppression effect or fire extinguishing effect through a suffocation effect.

[0085] In this case, if the energy storage element 10 is a ternary lithium battery, the gas contains oxygen, so there is a risk of ignition in the exhaust passage S1 immediately after release. However, the fire can be prevented from spreading due to the ignition suppression effect or fire extinguishing effect of the fire extinguishing agent.

[0086] On the other hand, if the energy storage element 10 is a lithium iron phosphate battery, even if gas is released, it does not contain oxygen, so ignition is unlikely near the gas discharge valve 160. However, it is prone to ignition near the exhaust port 37 of the exhaust passage S1 due to reaction with external oxygen. In such cases, a foam fire extinguishing agent can effectively suppress the phenomenon by cutting off the supply of oxygen.

[0087] (Modifications) Modifications of the above embodiments will be described below. In the following description, parts that are the same as those in the above embodiments or other modifications may be denoted by the same reference numerals and their descriptions may be omitted.

[0088] [Modification 1] Modification 1 of the above embodiment will now be described. In the above embodiment, an example was given of a storage element 10 having a container 100 in which the top surface 140 and the bottom surface 150 are both planes parallel to the XY plane. However, the top surface and the bottom surface may be curved.

[0089] Figure 11 is an exploded perspective view showing the energy storage device 1A according to Modification 1. Figure 12 is a perspective view showing the energy storage element 10a according to Modification 1. Figure 13 is an explanatory diagram showing the gas discharge valve 160a of each energy storage element 10a and the discharge valve 213a of each spacer 20a according to Modification 1.

[0090] As shown in Figures 11 and 12, the container 100a of the energy storage element 10a has a top surface 140a that is curved and protrudes in the positive Z-axis direction when viewed from the X-axis direction, and a bottom surface 150a that is curved and protrudes in the negative Z-axis direction. This container 100a also has a shape based on a rectangular parallelepiped, and is included in a shape in which at least one corner is cut off.

[0091] As shown in Figures 11 and 13, the spacer body 21a of the spacer 20a is formed in a rectangular shape when viewed in the Y-axis direction, and its length in the X-axis direction corresponds to the length in the X-axis direction of the top surface 140a and bottom surface 150a of the energy storage element 10a. An upper flange portion 221a extending in the X-axis direction is provided at the upper end of the spacer body 21a, and a lower flange portion 222a extending in the X-axis direction is provided at the lower end of the spacer body 21a. The upper flange portion 221a has a concave curved surface 223a that is in close contact with the top surface 140a of the adjacent energy storage element 10a. The lower flange portion 222a has a concave curved surface 224a that is in close contact with the bottom surface 150a of the adjacent energy storage element 10a.

[0092] A discharge valve 213a is positioned on at least one of the two end faces of the spacer body 21a in the X-axis direction. As shown in Figure 13, the gas discharge valve 160a and the discharge valve 213a are positioned adjacent to each other in the Y-axis direction.

[0093] [Modification 2] Modification 2 of the above embodiment will now be described. In the above embodiment, an example was given in which all four corners of the container 100 are rectangular first recesses (first recess 101 and second recess 102). In Modification 2, an example is given in which the lower pair of corners of the container 100b are chamfered first recesses 102b.

[0094] Figure 14 is a perspective view showing the energy storage element 10b according to Modified Example 2. Figure 15 is an explanatory diagram showing the gas discharge valve 160b of each energy storage element 10b and the discharge valve 213b of each spacer 20b according to Modified Example 2.

[0095] As shown in Figures 14 and 15, the container 100b of the energy storage element 10b has a rectangular parallelepiped shape, and the lower pair of corners are formed as notches 102b that penetrate the container 100b. The notches 102b are chamfered, and a gas discharge valve 160b is arranged on its inclined surface. On the top surface 140b of the container 100b, electrode terminals 300 and an external gasket 400 are arranged at both ends in the X-axis direction.

[0096] As shown in Figure 15, the spacer body 21b of the spacer 20b has a shape corresponding to the container 100b when viewed in the Y-axis direction. The spacer body 21b has a shape based on a rectangular parallelepiped, and the pair of lower corners are second notches 212b formed in the shape of notches that penetrate the spacer body 21b. The second notches 212b are formed in a chamfered shape, and the discharge valve 213b is arranged on its inclined surface. The gas discharge valve 160b and the discharge valve 213b are arranged adjacent to each other in the Y-axis direction.

[0097] (Other Modifications) Although an energy storage device according to an embodiment of the present invention (including its modifications; the same applies hereinafter) has been described above, the present invention is not limited to the above embodiments. The embodiments 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.

[0098] In the above embodiment, an energy storage device 1 having multiple spacers 20 was illustrated, but it is sufficient to provide at least one spacer 20.

[0099] In the above embodiment, the case in which the discharge valve 213 is positioned facing the exhaust passage S1 is illustrated, but the discharge valve does not have to be positioned facing the exhaust passage.

[0100] In the above embodiment, an energy storage element 10 having a first recess 101 and a second recess 102 was illustrated, but an energy storage element without a first recess may also be used.

[0101] In the above embodiment, a spacer 20 having a second notch 212 was illustrated, but a spacer without a second notch may also be used.

[0102] The present invention also includes forms constructed by arbitrarily combining the components included in the above embodiments and their modified examples.

[0103] This invention can be applied to energy storage elements such as lithium-ion secondary batteries.

[0104] 1, 1A Energy storage device 2 Case 10, 10a, 10b Energy storage element 20, 20a, 20b Spacer 21, 21a, 21b Spacer body 22 Encapsulation (inert gas, fire extinguishing agent) 30 Case body 31 Opening 32 Bottom wall 33 Side wall 37 Exhaust port 38 Check valve 40 Case lid 50 Control unit 51, 59 Pressure sensor 55 Valve opening part 56 Valve opening sensor 58 Temperature sensor 100, 100a, 100b Container 101 First recess (first cutout) 102 Second recess (first cutout) 102b First cutout 110 First side surface 120 Second side surface 130 Long side surface 140, 140a, 140b Top surface 150, 150a Bottom surface 160, 160a, 160b Gas discharge valve 212, 212b Second notch 213, 213a, 213b Discharge valve 221a Upper flange portion 222a Lower flange portion 223a, 224a Curved surface 300 Electrode terminal 371 Solenoid valve 400 External gasket L1 Dotted line S1 Exhaust passage

Claims

1. An energy storage device comprising: an energy storage element equipped with a gas discharge valve; a spacer positioned adjacent to the energy storage element; and a case capable of housing and sealing the energy storage element and the spacer, wherein the case is equipped with an exhaust section for exhausting the gas discharged from the gas discharge valve to the outside of the case, and the exhaust section is equipped with a check valve to prevent the flow of gas from the outside to the inside of the case.

2. The energy storage device according to claim 1, wherein the spacer comprises a spacer body, an inert gas contained within the spacer body, and a discharge valve provided on the spacer body that releases the inert gas when opened.

3. The energy storage device according to claim 1, wherein the spacer comprises a spacer body, a fire extinguishing agent enclosed within the spacer body, and a discharge valve provided on the spacer body for releasing the fire extinguishing agent when opened.

4. The energy storage device according to claim 2 or 3, wherein the discharge valve opens in conjunction with the opening of the gas discharge valve.

5. The energy storage device according to claim 4, further comprising: an opening sensor for detecting the opening of the gas discharge valve; and an opening unit for opening the discharge valve based on the detection by the opening sensor of the opening of the gas discharge valve.

6. The energy storage device according to claim 2 or 3, comprising an exhaust passage for the gas discharged from the gas discharge valve, wherein the discharge valve is positioned opposite the exhaust passage.

7. The energy storage device according to claim 2 or 3, comprising an electrode body and a container housing the electrode body, wherein the container is shaped based on a rectangular parallelepiped, and at least one corner of the rectangular parallelepiped is formed as a first notch that penetrates the container, and in the spacer body, a second notch that penetrates the spacer body is formed in a notch shape opposite to the first notch, the gas discharge valve is arranged in the first notch, and the discharge valve is arranged in the second notch.

8. The energy storage device according to claim 3, wherein the fire extinguishing agent is a foam fire extinguishing agent.

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