Power storage device

Abstract

To provide a power storage device which can prevent damage to an outer package even when gas is discharged from power storage elements housed in the outer package.SOLUTION: A power storage device 1 comprises: an outer package 10; a plurality of power storage elements 100; and a housing chamber formation member 30. The housing chamber formation member 30 forms a housing chamber 32 which is located at a position facing gas discharge valves 105 of consecutively aligned two or more power storage elements 100 among the plurality of power storage elements 100. The housing chamber 32 contains gas discharged from each of the gas discharge valves 105 of the two or more power storage elements 100. The housing chamber formation member 30 has a partition wall 33 which divides a space inside the housing chamber 32 from a space facing the gas discharge valves 105 of power storage elements 100 other than the two or more power storage elements 100. In each of the plurality of power storage elements 100, the gas discharge valve 105 is provided on a container 110 in such a manner that it can be opened to both the inside and the outside of the container 110.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an energy storage device including a plurality of energy storage elements and an exterior body that houses the plurality of energy storage elements. [Background technology]

[0002] Patent Document 1 discloses a battery module including a plurality of cells and a case that houses the cells. In this battery module, a flat plate arranged above the cells separates a housing section that houses the cells from an exhaust duct that exhausts gas from open sections of the cells to the outside of the case. The open sections of the cells communicate with the exhaust duct through openings formed in the flat plate. The exhaust duct is divided into a first space and a second space by a partition wall disposed between the flat plate and the exterior plate of the case, and the first space communicates with the second space through a through-hole formed in the partition wall. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-65906 Summary of the Invention [Problem to be solved by the invention]

[0004] The conventional battery module (electricity storage device) described above is configured to lower the temperature of gas discharged from the cells (electricity storage elements) by adiabatic expansion in the first space. However, in an energy storage element whose internal pressure has increased enough to discharge gas from the open portion (gas discharge valve), the temperature of the energy storage element itself also increases, and this heat may be transferred to other adjacent energy storage elements. Furthermore, a large current may flow to other adjacent energy storage elements due to a drop in voltage of the energy storage element from which gas has been discharged. Due to such factors, the gas discharge valve of the other energy storage element may also open (open) as the internal pressure of the container increases, causing high-temperature gas to be discharged. In this case, the strength of the exterior body of the energy storage device may be weakened by the heat of the energy storage elements and gas. Furthermore, the exterior body may be damaged by the increase in internal pressure due to gas discharged from the multiple energy storage elements. As a result, problems such as gas leakage from unexpected locations on the exterior body may occur.

[0005] The present invention was made by the inventor of the present application with a new focus on the above-mentioned problem, and aims to provide an energy storage device that can suppress damage to the outer casing even if gas is released from the energy storage element housed in the outer casing. [Means for solving the problem]

[0006] An energy storage device according to one embodiment of the present invention includes an outer casing; a plurality of energy storage elements housed in the outer casing and arranged in a second direction intersecting the first direction, with a gas exhaust valve provided on the container facing the first direction; and a storage chamber forming member disposed inside the outer casing at a position facing the gas exhaust valve of two or more consecutively arranged energy storage elements among the plurality of energy storage elements, and forming a storage chamber for storing gas exhausted from each of the two or more gas exhaust valves, wherein the storage chamber forming member has a partition wall portion separating the space inside the storage chamber from a space facing the gas exhaust valve of another energy storage element different from the two or more energy storage elements, and the gas exhaust valve of each of the plurality of energy storage elements is provided in the container in a state that allows it to be opened either toward the outside or the inside of the container.

[0007] According to this configuration, for example, the storage chamber formed at a position facing the gas release valves of two energy storage elements is a space partitioned from the space facing the gas release valves of the other energy storage elements. Therefore, if a malfunction occurs in one of the two energy storage elements, causing the gas release valve to open (valve open), the internal pressure of the storage chamber increases rapidly due to gas ejected from the gas release valve, thereby opening the gas release valve of the other energy storage element toward the interior of the container (inward). In other words, if one of two adjacent energy storage elements opens, there is a high probability that the other energy storage element will also open, causing gas to be ejected, due to heat or a voltage drop in the first energy storage element. Therefore, in the energy storage device of this embodiment, before the other energy storage element opens, causing gas to be ejected, the pressure of the gas ejected from the first energy storage element is used to open the other energy storage element inward. This reduces the possibility of sudden gas ejection from the other energy storage element. As a result, the possibility of the exterior body being damaged or destroyed due to being unable to withstand the heat and pressure of the gas emitted from the multiple energy storage elements, causing the gas to leak from unexpected locations, is reduced. Thus, with the energy storage device according to this aspect, damage to the exterior body can be suppressed even when gas is emitted from the energy storage elements housed in the exterior body.

[0008] The power storage device may further include a conductive member that electrically connects the two or more power storage elements in parallel.

[0009] Generally, when one of two or more parallel-connected energy storage elements opens, the voltage of that energy storage element drops sharply, causing a large current to flow through the remaining one or more energy storage elements. As a result, the remaining one or more energy storage elements are more likely to open, resulting in a sudden gas release. However, in the energy storage device according to this aspect, the storage chambers are provided opposite the gas release valves of the two or more parallel-connected energy storage elements. Therefore, when one energy storage element opens, the remaining one or more energy storage elements can be opened by an increase in internal pressure in the storage chamber before the valves open, resulting in a sudden gas release. This makes it possible to suppress damage to the exterior body when gas is released from the energy storage elements housed in the exterior body.

[0010] The conductive member may further electrically connect the two or more storage elements and the other storage element adjacent to the two or more storage elements in the second direction in series.

[0011] According to this configuration, two or more energy storage elements positioned opposite the storage chamber and other energy storage elements to the sides of the two or more energy storage elements are electrically connected in series. In other words, when one of the two or more energy storage elements opens, the other energy storage elements are unlikely to open due to electrical influences (direct influences of voltage fluctuations). In this situation, the space inside the storage chamber and the space facing the gas release valve of the other energy storage element are separated by a partition wall. Therefore, when one of the two or more energy storage elements opens, the gas pressure from the opened energy storage element does not act on the gas release valve of the other energy storage element. In other words, the gas pressure from the opened energy storage element can be prevented from acting on the other energy storage elements that do not need to be forced to open.

[0012] The storage chamber forming member may have a plurality of the storage chambers arranged in the second direction, and each of the plurality of storage chambers may be assigned a different storage element group consisting of two or more storage elements arranged consecutively from the plurality of storage elements.

[0013] According to this configuration, for example, the storage chambers are arranged in a many-to-one relationship for all of the multiple energy storage elements. As a result, when one of the multiple energy storage elements opens, the pressure of gas ejected from that energy storage element can be used to forcibly open one or more energy storage elements that have a high probability of opening and causing gas to be ejected due to the valve opening. In other words, damage to the exterior body when gas is ejected from the energy storage elements housed in the exterior body can be more reliably suppressed.

[0014] The storage chamber forming member may have an air hole that connects the inside of the storage chamber with the outside, and the opening area of ​​the air hole may be smaller than the opening area when the gas exhaust valve is open.

[0015] According to this configuration, when gas is ejected toward the storage chamber from one of the two or more energy storage elements facing the storage chamber, the gas can be released to the outside of the storage chamber through the vent hole while increasing the internal pressure of the storage chamber. In other words, the gas pressure from the one energy storage element with the valve open can be used to open the valves of the remaining one or more energy storage elements, and the gas can be discharged to the outside of the storage chamber. Therefore, gas from the energy storage element with the valve open can be discharged to the outside of the exterior body, for example, through a predetermined exhaust path within the exterior body. This more reliably prevents damage to the exterior body when gas is discharged from the energy storage elements housed in the exterior body. [Effects of the Invention]

[0016] According to the electricity storage device of the present invention, even when gas is discharged from the electricity storage elements housed in the exterior body, damage to the exterior body can be suppressed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view showing the appearance of a power storage device according to an embodiment; [Figure 2] FIG. 2 is an exploded perspective view of the electricity storage device according to the embodiment. [Figure 3] 1 is a perspective view showing the appearance of an energy storage element according to an embodiment; [Figure 4] 3 is a perspective view showing the structural relationship between an energy storage element array and a housing chamber forming member according to the embodiment. FIG. [Figure 5] 3 is a perspective cross-sectional view showing the structural relationship between an energy storage element array and a housing chamber forming member according to the embodiment. FIG. [Figure 6] FIG. 3 is a cross-sectional view schematically illustrating a gas flow inside an exterior body of the electricity storage device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, with reference to the drawings, a description will be given of an energy storage device according to an embodiment of the present invention (including its modified examples). Note that the embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, in each drawing, dimensions and the like are not strictly illustrated. Furthermore, in each drawing, the same or similar components are assigned the same reference numerals.

[0019] In the following description and drawings, the longitudinal direction of the exterior body of the energy storage device, the arrangement direction of multiple energy storage elements, or the opposing direction of the long side surfaces of the containers of the energy storage elements is defined as the X-axis direction. The lateral direction of the exterior body of the energy storage device, the opposing direction of the short side surfaces of the containers of the energy storage elements, or the arrangement direction of a pair of electrode terminals of one energy storage element is defined as the Y-axis direction. The arrangement direction of the main body and lid of the exterior body of the energy storage device, the arrangement direction of the bus bar holder and the energy storage element unit, or the up-down direction is defined as the Z-axis direction. The X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the mode of use, the Z-axis may not be the up-down direction; however, for convenience of explanation, the following description will be made assuming that the Z-axis direction is the up-down direction.

[0020] In the following description, for example, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis. Furthermore, simply referring to the "X-axis direction" means either or both directions parallel to the X-axis. The same applies to terms related to the Y-axis and Z-axis.

[0021] Furthermore, expressions indicating relative directions or attitudes, such as "parallel" and "orthogonal," also include cases where the directions or attitudes are not strictly those. For example, "two directions are orthogonal" does not only mean that the two directions are completely orthogonal, but also means that the two directions are substantially orthogonal, i.e., there is a difference of, for example, a few percent.

[0022] (Embodiment) [1. General description of the power storage device] First, a schematic configuration of an energy storage device 1 according to an embodiment will be described. Fig. 1 is a perspective view showing the appearance of the energy storage device 1 according to an embodiment. Fig. 2 is an exploded perspective view of the energy storage device 1 according to an embodiment. Fig. 3 is a perspective view showing the appearance of an energy storage element 100 according to an embodiment.

[0023] In addition to the components shown in Figure 2 and subsequent figures, the exterior body 10 also contains electrical equipment such as a control device and a relay, as well as wiring connected to the electrical equipment, but illustrations and descriptions of these components will be omitted as appropriate.

[0024] The power storage device 1 is a device that can charge with electricity from an external source and discharge electricity to the outside, and in this embodiment has a substantially rectangular parallelepiped shape. The power storage device 1 is, for example, a battery module (battery assembly) used for power storage or power supply purposes. Specifically, the power storage device 1 is used as a battery for driving or starting the engine of a mobile object such as an automobile, motorcycle, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, or electric railway vehicle. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline-powered vehicle. Examples of the electric railway vehicle include a train, a monorail, a linear motor car, and a hybrid train equipped with both a diesel engine and an electric motor. The power storage device 1 can also be used as a stationary battery for home or business use.

[0025] 1 and 2, the energy storage device 1 includes an exterior body 10 and an energy storage element unit 50 housed in the exterior body 10. The exterior body 10 is a box-shaped (substantially rectangular parallelepiped) container (module case) that constitutes the housing of the energy storage device 1. In other words, the exterior body 10 is disposed outside the energy storage element unit 50, fixes them in predetermined positions, and protects them from impacts and the like. The exterior body 10 is formed from an insulating material 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), polyether ether ketone (PEEK), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or a composite material thereof, or from a metal or the like with an insulating coating. This prevents the energy storage element unit 50 and the like from coming into contact with external metal members and the like. Note that the exterior body 10 may be formed from a conductive material such as a metal as long as electrical insulation is maintained between the exterior body 10 and the energy storage element unit 50 and the like.

[0026] The exterior body 10 includes an exterior body main body 12 and a lid body 11. The exterior body main body 12 is a bottomed, rectangular cylindrical housing with an opening 12a formed on the positive side of the Z axis, and houses the energy storage element unit 50 and other components. The lid body 11 is a rectangular member that closes the opening 12a of the exterior body main body 12. The lid body 11 is joined to the exterior body main body 12 by adhesive, heat sealing, ultrasonic welding, laser welding, or the like. A pair of external terminals 13, which are a pair of module terminals on the positive and negative sides, are disposed on the lid body 11. The energy storage device 1 charges with electricity from the outside and discharges electricity to the outside via the pair of external terminals 13. The external terminals 13 are formed of a conductive metal material such as aluminum, an aluminum alloy, copper, or a copper alloy. In this embodiment, the lid body 11 is further provided with an exhaust pipe 15 that forms a fluid path connecting the inside and outside of the exterior body 10. For example, when gas is discharged from gas discharge valve 105 of energy storage element 100, the gas is discharged to the outside of exterior body 10 via exhaust pipe 15.

[0027] The energy storage element unit 50 includes an energy storage element 100, a bus bar 60 electrically connected to the energy storage element 100, and an accommodating chamber forming member 30. In this embodiment, the accommodating chamber forming member 30 is disposed on an energy storage element array 101 configured with a plurality of (specifically, eight) energy storage elements 100 and a plurality of spacers 130 and 135. In this embodiment, the accommodating chamber forming member 30 has a gas storage portion 31 that forms an accommodating chamber that stores gas discharged from a gas discharge valve 105 of the energy storage element 100. The accommodating chamber forming member 30 further functions as a bus bar holder that holds or positions a plurality of bus bars 60. Details of the accommodating chamber forming member 30 will be described later with reference to FIGS. 4 to 6.

[0028] The energy storage element 100 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. As shown in FIG. 3 , the energy storage element 100 has a flat rectangular (square) container 110 and a pair of electrode terminals 120 (positive and negative) fixed to the container 110. The container 110 contains an electrode body, a current collector, an electrolyte, and the like (not shown). An example of the electrode body included in the energy storage element 100 is a wound-type electrode body formed by winding layers of positive and negative electrode plates with a separator sandwiched between them. Alternatively, the energy storage element 100 may be provided with a stack-type electrode body formed by stacking a plurality of flat electrode plates, or a bellows-type electrode body formed by folding electrode plates in a bellows shape.

[0029] The energy storage element 100 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 100 may not be a secondary battery, but may be a primary battery that allows stored electricity to be used without the user having to charge it. The energy storage element 100 may also be a pouch-type energy storage element. Furthermore, the shape of the energy storage element 100 is not limited to the above-mentioned rectangular shape, but may be other shapes such as a polygonal prism, a cylindrical shape, an elliptical cylindrical shape, or an oblong cylindrical shape.

[0030] In this embodiment, as shown in FIG. 3 , the container 110 has a pair of long side surfaces 110a, a pair of short side surfaces 110b, and a terminal arrangement surface 110c. The terminal arrangement surface 110c is a surface on which positive and negative electrode terminals 120 are arranged. In this embodiment, a gas release valve 105 is also arranged on the terminal arrangement surface 110c. The gas release valve 105 is formed, for example, by a thin-walled portion provided on a cover plate that forms the terminal arrangement surface 110c of the container 110. In other words, the gas release valve 105 is provided on the container 110 as a part that is weaker than other parts. As a result, the gas release valve 105 is deformed toward the outside of the container 110 due to the pressure inside the container 110 and is broken or destroyed, thereby allowing gas inside the container 110 to be released to the outside. Furthermore, the gas release valve 105 can be broken or destroyed while being deformed toward the inside of the container 110 by pressure outside the container 110, thereby releasing the airtight state of the container 110. In other words, the gas release valve 105 is provided in the container 110 in a state in which it can be opened toward both the outside and the inside of the container 110.

[0031] In the energy storage element array 101, the multiple energy storage elements 100 are aligned with their long side surfaces 110a facing the alignment direction (X-axis direction). In the multiple energy storage elements 100 aligned in this manner, one spacer 130 is arranged for every two energy storage elements 100, and spacers 135 are also arranged at both ends of the energy storage element array 101. The spacers 130 are, for example, components called intermediate spacers, and are arranged between two adjacent energy storage elements 100 as shown in FIG. 2. The spacers 130 electrically insulate the containers 110 of the two energy storage elements 100 from each other. The spacers 130 can also suppress heat conduction from one energy storage element 100 to the other energy storage element 100. The spacers 135 are, for example, components called end spacers, and protect the energy storage elements 100 at the ends in the alignment direction of the multiple energy storage elements 100 aligned in a row, and electrically insulate the energy storage elements 100 at those ends from other components. The energy storage element array 101 may be restrained in the arrangement direction of the energy storage elements 100 by a restraining member (not shown). In this case, even if the end plate of the restraining member is made of metal, the end plate and the energy storage element 100 adjacent to the end plate are electrically insulated by the spacer 135.

[0032] In this embodiment, of the eight energy storage elements 100 included in the energy storage element unit 50, two adjacent energy storage elements 100 are connected in parallel by a bus bar 60. This forms four sets of energy storage elements 100 connected in parallel. Furthermore, these four sets of energy storage elements 100 are connected in series by three bus bars 60. A bus bar 60 is joined to each of the total positive terminal 121 and the total negative terminal 122 of the energy storage element unit 50 having the eight energy storage elements 100 electrically connected in this manner. In this embodiment, as shown in FIG. 2 , the positive electrode terminals 120 of the two energy storage elements 100 at the end in the positive direction of the X axis are the total positive terminals 121, and the negative electrode terminals 120 of the two energy storage elements 100 at the end in the negative direction of the X axis are the total negative terminals 122. Note that the manner in which the eight energy storage elements 100 are electrically connected by the bus bars 60 is not limited to this, and for example, all eight energy storage elements 100 may be connected in series by a plurality of bus bars 60. Furthermore, the number of energy storage elements 100 included in the energy storage element unit 50 is not limited to eight. The number of energy storage elements 100 included in the energy storage element unit 50 may be two or more.

[0033] In the energy storage device 1 configured as described above, the storage chamber forming member 30 is fixed to the exterior body 10 in a position and orientation such that the gas storage section 31 covers the gas exhaust valves 105 of the plurality of energy storage elements 100. When one of the energy storage elements 100 opens, the gas storage section 31 temporarily stores the gas exhausted from that energy storage element 100. The gas storage section 31 is formed with a plurality of vent holes 32a (see FIG. 2 ), and the gas stored in the gas storage section 31 is exhausted to the outside of the gas storage section 31 through the vent holes 32a and further to the outside of the exterior body 10 via an exhaust pipe 15 provided in the exterior body 10. In this gas flow, the storage chamber forming member 30 can use the pressure of the gas exhausted from the energy storage element 100 to open the valve of the other energy storage elements 100. Hereinafter, the configuration of the storage chamber forming member 30 and its surroundings will be described in detail with reference to FIGS. 4 to 6.

[0034] [2. Configuration of the storage chamber forming member and its surroundings] FIG. 4 is a perspective view showing the structural relationship between an energy storage element array 101 and a storage chamber forming member 30 according to the embodiment. FIG. 4 illustrates a state in which the storage chamber forming member 30 is separated from the energy storage element array 101 including a plurality of energy storage elements 100, and a state in which a plurality of bus bars 60 are separated from the storage chamber forming member 30. FIG. 5 is a perspective cross-sectional view showing the structural relationship between the energy storage element array 101 and the storage chamber forming member 30 according to the embodiment. FIG. 5 illustrates a perspective view of the exterior body main body 12, the energy storage element array 101, and the storage chamber forming member 30 cut along an XZ plane passing through line VV in FIG. 4. FIG. 6 is a cross-sectional view schematically showing the flow of gas inside the exterior body 10 of the energy storage device 1 according to the embodiment. FIG. 6 illustrates simplified cross sections of the exterior body 10, the energy storage element array 101, and the storage chamber forming member 30, and the gas release valve 105 is schematically represented by a shaded rectangle.

[0035] The accommodating chamber forming member 30 is a member that is substantially rectangular when viewed from the positive direction of the Z axis (in a plan view) and that forms the accommodating chamber 32 that accommodates the gas discharged from the gas discharge valve 105 of the energy storage device 100. In this embodiment, the accommodating chamber forming member 30 is disposed opposite the terminal arrangement surface 110c, and also plays a role in holding or positioning the multiple bus bars 60. The accommodating chamber forming member 30 is formed, for example, from any of the electrically insulating resin materials that can be used for the exterior body 10 described above.

[0036] In this embodiment, the energy storage element array 101 has a plurality of energy storage elements 100 arranged in the X-axis direction with the gas release valves 105 facing in the positive direction of the Z-axis. Each of the plurality of energy storage elements 100 has the gas release valve 105 at the center of the terminal arrangement surface 110c in the Y-axis direction. As a result, the plurality of gas release valves 105 are arranged in a line in the X-axis direction. In this embodiment, the storage chamber forming member 30 is provided with a gas storage portion 31 that is elongated in the X-axis direction and bulges in the positive Z-axis direction so as to continuously cover the plurality of gas release valves 105 arranged in the X-axis direction. The positive Z-axis direction is an example of a first direction, the X-axis direction is an example of a second direction, and the Y-axis direction is an example of a third direction.

[0037] In this embodiment, the energy storage element array 101 has eight energy storage elements 100, and when these energy storage elements 100 are described below while being distinguished from one another, they will be assigned different reference numerals (100a to 100h, see FIG. 4). Similarly, when these six bus bars 60 are described below while being distinguished from one another, they will be assigned different reference numerals (60A to 60E, see FIG. 4). Furthermore, two adjacent energy storage elements 100 will be referred to as an energy storage element group 108, and when the four energy storage element groups 108 included in the energy storage element array 101 are described below while being distinguished from one another, they will be assigned different reference numerals (108A to 108D).

[0038] As shown in FIGS. 4 to 6 , among the eight energy storage elements 100, storage chambers 32 formed in the gas storage section 31 are arranged at positions facing the gas release valves 105 of the energy storage elements 100a and 100b included in the energy storage element group 108A. Furthermore, storage chambers 32 formed in the gas storage section 31 are arranged at positions facing the gas release valves 105 of the energy storage elements 100c and 100d included in the energy storage element group 108B. These two storage chambers 32 are separated by a partition wall 33. In other words, one storage chamber 32 is provided corresponding to each of the multiple energy storage element groups 108, and two adjacent storage chambers 32 are separated by the partition wall 33.

[0039] In this configuration, for example, as shown in FIG. 6 , assume that energy storage element 100a becomes hot due to some abnormality, causing the electrolyte to suddenly vaporize, and as a result, gas release valve 105 of energy storage element 100a opens toward the outside of container 110. In this case, a large amount of high-temperature gas is released from energy storage element 100a, causing an instantaneous increase in the internal pressure of storage chamber 32 located opposite energy storage element 100a. As a result, gas release valve 105 of energy storage element 100b located opposite storage chamber 32 opens toward the inside of container 110 in response to the increase in internal pressure of storage chamber 32, thereby releasing the airtight state of container 110 for energy storage element 100b. In this case, it is unlikely that energy storage element 100b will release high-temperature gas due to heat or a voltage drop from adjacent energy storage element 100a. That is, in the energy storage device 1, damage to the exterior housing 10 when gas is discharged from the energy storage elements 100a housed in the exterior housing 10 is suppressed.

[0040] As described above, the energy storage device 1 according to the present embodiment includes an exterior housing 10, a plurality of energy storage elements 100 accommodated in the exterior housing 10, and a storage chamber-forming member 30. The plurality of energy storage elements 100 are aligned in the X-axis direction with the gas release valves 105 provided on the containers 110 facing the positive direction of the Z-axis. The storage chamber-forming member 30 forms, inside the exterior housing 10, storage chambers 32 arranged at positions facing the gas release valves 105 of two or more consecutively arranged energy storage elements 100. The storage chambers 32 accommodate gases released from the gas release valves 105 of the two or more energy storage elements 100. The storage chamber-forming member 30 has a partition wall portion 33 that separates the space inside the storage chamber 32 from a space facing the gas release valves 105 of the other energy storage elements 100 different from the two or more energy storage elements 100. In each of the plurality of energy storage elements 100, the gas release valve 105 is provided in the container 110 in a state in which it can be opened both to the outside and the inside of the container 110.

[0041] 4 to 6, the storage chamber 32 formed at a position facing the gas release valves 105 of the two energy storage elements 100 is a space partitioned from the space facing the gas release valves 105 of the other energy storage elements 100. Therefore, if some kind of malfunction occurs in one of the two energy storage elements 100 and the gas release valve 105 is opened (opened), the internal pressure of the storage chamber 32 will rise rapidly due to the gas ejected from the gas release valve 105, which will cause the gas release valve 105 of the other energy storage element 100 to open (inward) toward the inside of the container 110.

[0042] That is, when one of two adjacent energy storage elements 100 opens, there is a high probability that the other will also open, accompanied by a sudden gas release, due to heat or a voltage drop from the first energy storage element. Therefore, in the energy storage device 1 according to the present embodiment, before the other energy storage element 100 opens, accompanied by a sudden gas release, the pressure of the gas released from the first energy storage element 100 is used to open the valve of the other energy storage element 100 inward. This reduces the possibility of sudden gas release from the other energy storage element 100. As a result, the possibility of the exterior body 10 being damaged or destroyed due to being unable to withstand the heat and pressure caused by the gas released from the multiple energy storage elements 100, resulting in gas leaking from an unexpected location in the exterior body 10, is reduced. Thus, the energy storage device 1 according to the present embodiment can suppress damage to the exterior body 10 even when gas is released from the energy storage elements 100 housed in the exterior body 10.

[0043] In addition, in this embodiment, the energy storage device 1 includes bus bars 60 that electrically connect in parallel two or more energy storage elements 100 corresponding to one accommodation chamber 32. Specifically, as shown in Fig. 4, energy storage elements 100a and 100b are connected in parallel by bus bars 60A and 60B, and energy storage elements 100c and 100d are connected in parallel by bus bars 60B and 60C. Energy storage elements 100e and 100f are connected in parallel by bus bars 60C and 60D, and energy storage elements 100g and 100h are connected in parallel by bus bars 60D and 60E.

[0044] Generally, when one of two or more parallel-connected energy storage elements 100 opens, the voltage of the energy storage element 100 drops suddenly, causing a large current to flow through the remaining one or more energy storage elements 100. As a result, the remaining one or more energy storage elements 100 are more likely to open, causing a sudden gas release. However, in the energy storage device 1 according to the present embodiment, the storage chamber 32 is provided at a position facing the gas release valves 105 of the two or more parallel-connected energy storage elements 100. Therefore, when one energy storage element 100 opens, the remaining one or more energy storage elements 100 can be opened before the valve opening, causing a sudden gas release, occurs. For example, as shown in FIG. 6, when the energy storage element 100a opens, the internal pressure of the storage chamber 32 due to the gas released from the energy storage element 100a causes the energy storage element 100b to open (including at least a portion of the gas release valve 105 being broken or destroyed). That is, in the energy storage element 100b, the internal pressure of the accommodation chamber 32 can release the airtight state of the container 110 of the energy storage element 100b before the internal pressure of the container 110 opens the gas release valve 105. As a result, the ejection of high-temperature gas from the energy storage element 100b is substantially prevented. This makes it possible to suppress damage to the exterior body 10 when gas is released from the energy storage element 100a accommodated in the exterior body 10.

[0045] In the present embodiment, the bus bar 60 further electrically connects two or more energy storage elements 100 and other energy storage elements 100 adjacent to the two or more energy storage elements 100 in the X-axis direction in series. Specifically, as shown in FIG. 4 , the bus bar 60B connects the energy storage elements 100a and 100b in parallel, and connects the energy storage elements 100a and 100b in series with the energy storage element 100c. More specifically, the bus bar 60B connects the energy storage element group 108A consisting of the energy storage elements 100a and 100b in series with the energy storage element group 108B consisting of the energy storage elements 100c and 100d. Similarly, the bus bar 60C connects the energy storage element group 108B in series with the energy storage element group 108C, and the bus bar 60D connects the energy storage element group 108C in series with the energy storage element group 108D.

[0046] That is, two or more energy storage elements 100 located opposite one storage chamber 32 and other energy storage elements 100 on the side of the two or more energy storage elements 100 are electrically connected in series. That is, when one of the two or more energy storage elements 100 opens, the other energy storage elements 100 are unlikely to open due to an electrical influence (direct influence of voltage fluctuation). For example, when the energy storage element 100a or 100b opens, the energy storage element 100c connected in series to the energy storage element 100a or 100b is unlikely to open due to a voltage drop of the energy storage element 100a or 100b. In this situation, the internal space of the accommodation chamber 32 facing the energy storage elements 100a and 100b (energy storage element group 108A) is separated from the internal space of the accommodation chamber 32 facing the energy storage elements 100c and 100d (energy storage element group 108B) by the partition wall portion 33. Therefore, when either the energy storage element 100a or 100b is opened, the gas pressure from the opened energy storage element 100 does not act on the gas release valves 105 of the energy storage elements 100c and 100d. In other words, the gas pressure from the opened energy storage element 100 can be prevented from acting on the other energy storage elements 100 that do not need to be forcibly opened, and can be efficiently used to open the energy storage elements 100 that need to be forcibly opened.

[0047] Moreover, in this embodiment, the storage chamber forming member 30 has a plurality of storage chambers 32 lined up in the X-axis direction. Each of the plurality of storage chambers 32 is assigned to a different energy storage element group 108, which is made up of two or more energy storage elements lined up consecutively among the plurality of energy storage elements 100. Specifically, the storage chamber forming member 30 has an elongated gas storage section 31 in the X-axis direction, and the gas storage section 31 includes four storage chambers 32 lined up in the X-axis direction. Each of these four storage chambers 32 is assigned to one of four energy storage element groups 108A to 108D, each including two energy storage elements 100.

[0048] According to this configuration, the accommodation chambers 32 are arranged in an M-to-1 relationship (M is an integer equal to or less than N and equal to or greater than 2) for all of the N (N is an integer equal to or greater than 2) energy storage elements 100. As a result, when any of the M energy storage elements 100 opens, the pressure of gas ejected from that energy storage element 100 can be used to forcibly open one or more energy storage elements 100 that have become more likely to open due to the effect of the opening, accompanied by a sudden ejection of gas. In other words, damage to the exterior body 10 when gas is ejected from the energy storage elements 100 accommodated in the exterior body 10 can be more reliably suppressed.

[0049] Furthermore, in this embodiment, the storage chamber forming member 30 has an air vent 32a that communicates the inside and outside of the storage chamber 32. The opening area of ​​the air vent 32a is smaller than the opening area when the gas release valve 105 is open, as shown in FIGS. 4 and 5, for example. Specifically, the shape of the gas release valve 105 of the energy storage element 100 in a plan view is oval, as shown in FIGS. 3 and 4, for example. The area of ​​the oval is defined as the opening area when the gas release valve 105 is open. When this opening area is compared with the opening area of ​​the circular air vent 32a shown in FIG. 4, for example, the opening area of ​​the air vent 32a is smaller. Note that if the area of ​​the air vent 32a in a plan view is not constant in the gas passage direction (Z-axis direction) of the air vent 32a, the minimum value of the area in a plan view is defined as the opening area of ​​the air vent 32a.

[0050] According to this configuration, when gas is ejected toward the storage chamber 32 from one of the two or more energy storage elements 100 facing the storage chamber 32, the gas can be released to the outside of the storage chamber 32 through the vent 32a while increasing the internal pressure of the storage chamber 32. In other words, the pressure of the gas from the one energy storage element 100 whose valve is open can be used to open the valves of the remaining one or more energy storage elements 100, and the gas can be discharged to the outside of the storage chamber 32. Therefore, for example, the gas from the energy storage element 100 whose valve is open can be discharged to the outside of the exterior body 10 through a predetermined exhaust path within the exterior body 10. In this embodiment, as shown in FIGS. 1 and 6 , an exhaust pipe 15 is provided in the cover 11 of the exterior body 10. The gas discharged from the energy storage element 100 and used to open the valves of the other energy storage elements 100 is discharged to the outside of the exterior body 10 through the vent 32a of the storage chamber 32 and the exhaust pipe 15. This makes it possible to more reliably prevent damage to the exterior body 10 when gas is discharged from the energy storage device 100 housed in the exterior body 10.

[0051] Preferably, the vent hole 32a is disposed at a position that does not face the gas exhaust valve 105. In this embodiment, as shown in FIG. 6 , in one storage chamber 32 corresponding to two gas exhaust valves 105 aligned in the X-axis direction, the vent hole 32a is disposed at a position between the two gas exhaust valves 105 in the X-axis direction. This prevents gas ejected from the gas exhaust valve 105 from being directly ejected to the outside of the storage chamber 32 through the vent hole 32a. As a result, the gas ejected from the gas exhaust valve 105 can be efficiently used to increase the internal pressure of the storage chamber 32. Furthermore, a plate made of a highly insulating or heat-resistant material may be disposed on the top surface (inner surface in the positive direction of the Z-axis) of the storage chamber 32. Alternatively, the top surface itself may be formed of a highly insulating or heat-resistant material. In either case, damage to the storage chamber-forming member 30 caused by high-temperature gas ejected from the gas exhaust valve 105 can be suppressed.

[0052] [3. Modifications] Although the energy storage device 1 according to the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. In other words, the embodiment disclosed herein is illustrative in all respects and is not restrictive, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0053] For example, the number of energy storage elements 100 electrically connected in parallel included in one energy storage element group 108 may be three or more. For example, when three energy storage elements 100, energy storage elements 100a to 100c, are electrically connected in parallel, if the energy storage element 100a opens and the voltage drops, a large current may flow not only to the energy storage element 100b but also to the energy storage element 100c. For this reason, the accommodation chamber 32 is disposed at a position facing the gas release valves 105 of these three energy storage elements 100. This makes it possible to use the pressure of the gas ejected from the energy storage element 100a to open the gas release valves 105 of the energy storage elements 100b and 100c inward.

[0054] Furthermore, the shape of the accommodation chamber 32 does not need to be rectangular parallelepiped, and may be, for example, hemispherical or frustum-shaped. Furthermore, the position of the vent hole 32a provided in the accommodation chamber 32 does not need to be on the positive side of the Z axis. For example, the vent hole 32a may be disposed on the side wall of the accommodation chamber 32 in the Y axis direction. That is, the shape of the accommodation chamber 32 (gas storage section 31) and the position of the vent hole 32a may be determined appropriately, for example, taking into consideration the layout of other elements (electrical devices such as relays, wiring, etc.) disposed around the accommodation chamber-forming member 30. Furthermore, for example, in the accommodation chamber-forming member 30, a portion functioning as a bus bar holder (a portion that holds or positions the bus bar 60) and the gas storage section 31 may be formed from separate members. Furthermore, in the gas storage section 31, each of the multiple accommodation chambers 32 may be formed from a separate member. As a result, for example, when manufacturing multiple types of power storage devices each requiring a different number of accommodation chambers 32, a single component for forming the accommodation chamber 32 can be commonly used to manufacture these multiple types of power storage devices.

[0055] Furthermore, the storage chamber forming member 30 does not need to have a portion that holds or positions the bus bar 60. In other words, the storage chamber forming member 30 only needs to have a portion that forms one or more storage chambers 32 (gas storage section 31 in this embodiment), and the role of holding the bus bar 60 may be performed by another member. This makes it possible to suppress an increase in the overall weight of the storage chamber forming member 30, for example, when the storage chamber forming member 30 is formed of a material that contains a metal and has a relatively high specific gravity in order to improve durability against gas ejected from the energy storage device 100.

[0056] Furthermore, the conductive member that connects the plurality of energy storage elements 100 in parallel or in series does not need to be a rigid metal body such as the bus bar 60. For example, the plurality of energy storage elements 100 may be connected in parallel or in series by a flexible coated electric wire (cable).

[0057] Furthermore, configurations constructed by arbitrarily combining the components included in the above-described embodiments and their modifications are also included within the scope of the present invention. [Industrial Applicability]

[0058] The present invention can be applied to an electricity storage device including an electricity storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0059] 1. Energy storage device 10. Exterior body 15 exhaust pipe 30 Storage chamber forming member 32 Containment Room 32a Ventilation hole 33 Partition wall 100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h Storage element 101 Storage element array 105 Gas exhaust valve 108, 108A, 108B, 108C, 108D storage element group 110 Container

Claims

1. An exterior body; a plurality of energy storage elements housed in the exterior body and arranged in a second direction intersecting the first direction with a gas release valve provided in the container facing a first direction; a storage chamber forming member that is disposed inside the exterior body at a position facing the gas release valves of two or more consecutively arranged energy storage elements among the plurality of energy storage elements, and that forms a storage chamber that contains gas released from each of the two or more gas release valves, the storage chamber forming member has a partition wall portion that separates an internal space of the storage chamber from a space facing the gas release valve of another energy storage element different from the two or more energy storage elements, In each of the plurality of energy storage elements, the gas release valve is provided in the container in a state that the gas release valve can be opened toward either the outside or the inside of the container, Further, a conductive member is provided to electrically connect the two or more energy storage elements, the accommodation chamber forming member integrally includes a portion for holding or positioning the conductive member and a gas accommodation portion for forming the accommodation chamber; Energy storage device.

2. The conductive member electrically connects the two or more storage elements in parallel. The electricity storage device according to claim 1.

3. The conductive member further electrically connects the two or more storage elements and the other storage element adjacent to the two or more storage elements in the second direction in series. The electricity storage device according to claim 2.

4. the storage chamber forming member has a plurality of the storage chambers arranged in the second direction, Each of the plurality of storage chambers is assigned a different energy storage element group, the energy storage element group being composed of two or more energy storage elements arranged consecutively among the plurality of energy storage elements. The electricity storage device according to any one of claims 1 to 3.

5. the storage chamber forming member has an air hole that communicates the inside and the outside of the storage chamber, The opening area of ​​the vent hole is smaller than the opening area when the gas exhaust valve is open. The electricity storage device according to any one of claims 1 to 4.

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