Energy storage module and energy storage unit

Abstract

An energy storage unit (1) and an energy storage module (2) comprise: an energy storage device (10) having a pack (11) formed from a laminated film and an electrode laminate (12) encased in the pack (11); a case (20) that holds the energy storage device (10); and a blade member (24) provided in the case (20) to open a hole in a swollen portion of the pack (11) when the pack (11) has become swollen, wherein the blade member (24) is formed from an insulating material, and a groove (24a) is formed on a lateral surface of the blade member (24), extending from the blade tip side to the root side of the blade member (24).

Description

Energy storage module and energy storage unit

[0001] The present disclosure relates to an electricity storage module having an electricity storage device such as a lithium ion capacitor, and an electricity storage unit including the same.

[0002] Secondary batteries or capacitors are used as chargeable and dischargeable electricity storage devices in automobiles, electrical appliances, etc. The electricity storage device is held in a case to form an electricity storage module. Furthermore, an electricity storage unit is formed by unitizing the electricity storage module and a circuit board.

[0003] In recent years, development of nonaqueous electrolytic electricity storage devices has been progressing as electricity storage devices, in which lithium ions can be charged and discharged by moving between a positive electrode and a negative electrode. Known examples of this type of electricity storage device include lithium ion batteries and lithium ion capacitors. For example, lithium ion capacitors are used as backup power sources for electric power steering in automobiles.

[0004] A lithium ion battery or a lithium ion capacitor includes an electrode stack in which a positive electrode, a negative electrode, and a separator are stacked, and a pack (container) made of a laminate film that houses the electrode stack.

[0005] In an electricity storage device with such a configuration, if it is exposed to a high temperature environment or is overcharged, gas may be generated inside the pack. When gas is generated inside the pack, the internal pressure of the pack increases, causing the pack to expand. This may result in the pack exploding.

[0006] To address this issue, a technology has been proposed in the past in which a metal frame with sharp metal protrusions is wrapped around the pack of an electricity storage device (see Patent Document 1). With this configuration, when the pack expands, the protrusions pierce the laminate film that forms the outer casing of the pack, creating holes in the pack. This allows gas inside the pack to escape when the pack expands, thereby preventing the pack from bursting.

[0007] JP 2012-74300 A

[0008] However, with the technology disclosed in Patent Document 1, when a hole is made in the pack with the protrusion, the protrusion may pierce the electrode stack, causing a risk of short-circuiting the electrode stack. In other words, there is a risk of short-circuiting between the positive and negative electrodes that constitute the electrode stack. In particular, since the protrusions in Patent Document 1 are made of metal, if the protrusions pierce the electrode stack, the electrode stack will short-circuit. Furthermore, with the technology disclosed in Patent Document 1, a metal frame must be provided in addition to the case that holds the electricity storage device, which is costly.

[0009] Furthermore, with the conventional projection shape, when a hole is made in the pack with the projection, a gap is not formed between the pack and the projection that pierces the pack, and the gas inside the pack cannot be sufficiently released. In particular, when the pressure due to the expansion of the pack is large, even if the projection pierces the pack, a gap may not be formed between the projection and the pack.

[0010] The present disclosure has been made to solve such problems, and aims to provide an energy storage module and an energy storage unit that can stably release gas inside the pack by drilling a hole in the pack when the pack expands, without shorting the electrode stack and without incurring any cost.

[0011] In order to achieve the above object, one aspect of the energy storage module according to the present disclosure comprises an energy storage device having a pack made of a laminate film and an electrode stack contained in the pack, a case for holding the energy storage device, and a blade member provided in the case for punching a hole in an expanding portion of the pack when the pack expands, the blade member being made of an insulating material, and having a groove formed on a side of the blade member extending from the cutting edge side to the base side of the blade member.

[0012] Furthermore, one aspect of the energy storage unit according to the present disclosure includes the above-described energy storage module, a circuit board on which electronic components for controlling the energy storage device in the energy storage module are mounted, and a housing that houses the energy storage module and the circuit board.

[0013] According to the present disclosure, when the pack expands, holes can be drilled in the pack to allow gas inside the pack to escape stably without shorting the electrode stack and without incurring additional costs.

[0014] 1 is a perspective view of an energy storage unit according to an embodiment when viewed from diagonally above. FIG. 2 is a perspective view of an energy storage unit according to an embodiment when viewed from diagonally below. FIG. 3 is an exploded perspective view of an energy storage unit according to an embodiment with a second external cover of the housing removed. FIG. 4 is an exploded perspective view of an energy storage unit according to an embodiment when the energy storage module has been removed from the second external cover of the housing. FIG. 5 is an exploded perspective view of an energy storage module according to an embodiment. FIG. 6 is a cross-sectional view in the longitudinal direction of an energy storage unit according to an embodiment. FIG. 7 is a cross-sectional view in the lateral direction of an energy storage unit according to an embodiment. FIG. 8 is an external perspective view of an energy storage device according to an embodiment. FIG. 9 is a cross-sectional perspective view of an energy storage unit according to an embodiment. FIG. 10 is a cross-sectional view of an energy storage unit according to an embodiment. FIG. 11 is a perspective view of a first external cover of a housing in an energy storage unit according to an embodiment when viewed from diagonally above. FIG. 12 is a perspective view of the first external cover of a housing in an energy storage unit according to an embodiment when viewed from diagonally below. FIG. 13 is a cross-sectional view in the longitudinal direction of an energy storage unit when the first energy storage device is expanded. FIG. 14 is a cross-sectional view in the lateral direction of an energy storage unit when the second energy storage device is expanded. 10A and 10B are cross-sectional views in the short side direction of the electricity storage unit when the second electricity storage device is expanded, respectively; FIG. 10B are partially enlarged cross-sectional views of the electricity storage unit according to Modification 1; and FIG. 10C are partially enlarged cross-sectional views of the electricity storage unit according to Modification 2.

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components not recited in independent claims will be described as optional components.

[0016] Note that each figure is a schematic diagram and is not necessarily a precise illustration. Furthermore, in each figure, substantially the same configuration is assigned the same reference numeral, and duplicate explanations are omitted or simplified. Furthermore, in this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition.

[0017] (Embodiment) An energy storage unit 1 according to an embodiment will be described with reference to FIGS. 1 to 9. FIGS. 1 and 2 are perspective views of the energy storage unit 1 according to the embodiment. FIG. 1 shows the external appearance of the energy storage unit 1 when viewed obliquely from above, and FIG. 2 shows the external appearance of the energy storage unit 1 when viewed obliquely from below. FIGS. 3 and 4 are exploded perspective views of the energy storage unit 1. FIG. 3 shows a state in which the second outer cover 50b of the housing 50 is removed, and FIG. 4 shows a state in which the energy storage module 2 is removed from the second outer cover 50b. FIG. 5 is an exploded perspective view of the energy storage module 2 according to the embodiment. FIGS. 6 and 7 are cross-sectional views of the energy storage unit 1. FIG. 6 shows a cross-section of the energy storage unit 1 taken along the longitudinal direction, and FIG. 7 shows a cross-section of the energy storage unit 1 taken along the lateral direction. FIG. 8 is an external perspective view of the energy storage device 10 in the energy storage unit 1, and FIG. 9 is a cross-sectional perspective view of the energy storage device 10.

[0018] 1 to 7 , the energy storage unit 1 includes an energy storage device 10, a case 20 that holds the energy storage device 10, and an inner cover 30 that covers the energy storage device 10. The energy storage device 10, the case 20, and the inner cover 30 constitute an energy storage module 2. In other words, the energy storage module 2 includes the energy storage device 10, the case 20, and the inner cover 30. The case 20 and the inner cover 30 constitute outer members of the energy storage module 2. The energy storage module 2 in this embodiment is a thin energy storage module that has a substantially rectangular parallelepiped shape as a whole.

[0019] The energy storage unit 1 includes the energy storage module 2 and a circuit board 40 on which electronic components for controlling the energy storage device 10 in the energy storage module 2 are mounted. The energy storage unit 1 is a unit formed by combining the energy storage module 2 and the circuit board 40.

[0020] The energy storage unit 1 further includes a housing 50 that houses the energy storage module 2 and the circuit board 40. Specifically, the housing 50 houses the energy storage device 10, the case 20, the inner cover 30, and the circuit board 40. The housing 50 forms an outer casing member of the energy storage unit 1.

[0021] The power storage unit 1 in this embodiment is a thin power storage unit that has a generally rectangular parallelepiped shape as a whole. The power storage unit 1 configured in this manner is used, for example, as a power source for an automobile or the like. As an example, the power storage unit 1 is used as a backup power source for an electric power steering of an automobile.

[0022] In the present embodiment, the energy storage module 2 includes two energy storage devices 10. One of the two energy storage devices 10 is a first energy storage device 10a located on the circuit board 40 side, and the other of the two energy storage devices 10 is a second energy storage device 10b located on the opposite side from the circuit board 40 side. Specifically, the first energy storage device 10a is located on the lower side of the case 20, and the second energy storage device 10b is located on the upper side of the case 20. The first energy storage device 10a and the second energy storage device 10b are electrically connected by a bus bar 60. In the present embodiment, the first energy storage device 10a and the second energy storage device 10b are coupled to each other so as to be connected in series. Note that, although the first energy storage device 10a and the second energy storage device 10b are the same, this is not a limitation.

[0023] Furthermore, since the energy storage module 2 includes two energy storage devices 10, the energy storage unit 1 includes two internal covers 30. Specifically, the energy storage unit 1 includes, as the internal covers 30, a first internal cover 30a that covers the first energy storage device 10a and a second internal cover 30b that covers the second energy storage device 10b. The first internal cover 30a is a lower cover that covers the first energy storage device 10a located on the lower side, and the second internal cover 30b is an upper cover that covers the second energy storage device 10b located on the upper side.

[0024] The electricity storage device 10 is a chargeable and dischargeable device. In this embodiment, the electricity storage device 10 is a nonaqueous electrolytic electricity storage device that can be charged and discharged by lithium ions moving between a positive electrode and a negative electrode. Specifically, the electricity storage device 10 is a lithium ion capacitor (LIC).

[0025] As shown in FIGS. 8 and 9 , the electricity storage device 10 includes a pack 11 made of a laminate film, an electrode stack 12 contained in the pack 11 , and a pair of terminals 13 extending from the pack 11 .

[0026] The pack 11 is a container that constitutes the exterior of the electricity storage device 10. In this embodiment, the pack 11 uses a metal laminate film made of aluminum as an exterior film, and is formed into a bag shape by overlapping this metal laminate film and sealing the outer periphery in a strip shape. Therefore, the pack 11 is a pouch having a sealing portion 11a formed in a strip shape along the outer periphery of the metal laminate film, and is hermetically sealed by this sealing portion 11a. In this embodiment, the pack 11 is hermetically sealed by heat welding the metal laminate film along the outer periphery of the pack 11. In other words, the sealing portion 11a is a heat-welded portion where the metal laminate film is heat-welded. This sealing by heat welding is performed with the electrode stack 12 and a pair of terminals 13 sandwiched between the front and back laminate films.

[0027] The pack 11 has a rectangular shape when viewed from above. That is, the metal laminate film constituting the exterior film of the pack 11 has a rectangular shape when viewed from above. In the present embodiment, the exterior film of the pack 11 is made of aluminum, but this is not limited thereto. The exterior film of the pack 11 may also be made of a metal material other than aluminum.

[0028] The electrode stack 12 housed in the pack 11 has a structure in which a positive electrode, a negative electrode, and a separator are stacked. Specifically, the electrode stack 12 has a structure in which positive electrodes and negative electrodes, each formed into a sheet shape, are alternately stacked with a separator interposed therebetween. Since the electricity storage device 10 in this embodiment is a lithium ion capacitor, for example, the positive electrode has a structure in which a positive electrode material made of a carbon material such as activated carbon is formed on a positive electrode current collector, and the negative electrode has a structure in which a negative electrode material made of a material capable of absorbing and releasing lithium ions (for example, a carbon material such as graphite carbon) is formed on a negative electrode current collector.

[0029] Although not shown, the electricity storage device 10 further includes an electrolyte solution. Specifically, the pack 11 containing the electrode stack 12 is filled with the electrolyte solution. Since the electricity storage device 10 in this embodiment is a lithium ion capacitor, the electrolyte solution contains, for example, a lithium compound as an electrolyte and a solvent.

[0030] The pair of terminals 13 are extraction electrodes drawn out from the pack 11. The pair of terminals 13 are electrically connected to the electrode stack 12. Specifically, one of the pair of terminals 13 is a positive electrode terminal electrically connected to the positive electrode of the electrode stack 12, and the other of the pair of terminals 13 is a negative electrode terminal electrically connected to the negative electrode of the electrode stack 12.

[0031] The pair of terminals 13 also function as external connection terminals for electrically connecting the power storage device 10 to other components. In the present embodiment, each of the pair of terminals 13 is electrically connected to an electronic component mounted on the circuit board 40 via a bus bar 60. Specifically, for each of the two power storage devices 10, a bus bar 60 is coupled to each of the pair of terminals 13. The bus bars 60 connected to each of the pair of terminals 13 in the two power storage devices 10 are then connected to each other so that the two power storage devices 10 are connected in series. The bus bars 60 connected to each of the pair of terminals 13 in each power storage device 10 are electrically connected to wiring on the circuit board 40. The bus bars 60 are fixed to the circuit board 40 with screws 72.

[0032] The power storage device 10 is held in a case 20. The case 20 is a holder for holding the power storage device 10. Specifically, the case 20 has a storage section 21 for storing the power storage device 10 in order to hold the power storage device 10. The power storage device 10 stored in the storage section 21 is fixed to the case 20.

[0033] The storage section 21 is composed of a side wall 22 that surrounds the periphery of the electricity storage device 10 and a support section 23 that supports the electricity storage device 10. The side wall 22 and the support section 23 are formed in a concave shape (box shape) having a bottom.

[0034] The side wall 22 is located on a side of the pack 11 of the electricity storage device 10. The side wall 22 surrounding the pack 11 has a frame shape when viewed from above. In the present embodiment, the pack 11 of the electricity storage device 10 has a rectangular shape when viewed from above, and therefore the side wall 22 also has a rectangular frame shape when viewed from above. Specifically, the shape of the side wall 22 when viewed from above is a rectangular frame shape.

[0035] The rectangular frame-shaped side wall 22 abuts against the side surfaces of three of the four sides of the pack 11 of the electricity storage device 10 when the pack 11 expands or before the pack 11 expands. In the present embodiment, the portions of the side wall 22 corresponding to three of the four sides are provided in close proximity to the side surfaces of the pack 11 of the electricity storage device 10 arranged in the storage section 21 with a gap between them and the side surfaces of the pack 11. Therefore, the portions of the side wall 22 corresponding to one of the four sides other than the three sides are provided farther away from the side surfaces of the pack 11 than the portions of the side wall 22 corresponding to the three sides, and do not abut against the pack 11 either before or after the pack 11 expands. Specifically, the portions of the two short sides of the side wall 22 that face the short side of the pack 11 from which the pair of terminals 13 are pulled out are spaced apart from the side surface of the short side of the pack 11, and the portions of the side wall 22 that correspond to the two long sides and the remaining short side are close to the side surface of the pack 11.

[0036] In this embodiment, the side wall 22 has a double structure consisting of a rectangular frame-shaped outer wall 22b and a frame-shaped inner wall 22a provided inside the outer wall 22b. The distance between the outer wall 22b and the inner wall 22a is constant around the entire circumference of the side wall 22. A plurality of connecting walls 22c are provided between the outer wall 22b and the inner wall 22a, connecting the outer wall 22b and the inner wall 22a. The plurality of connecting walls 22c are erected on the outer wall 22b and the inner wall 22a and are provided at equal intervals around the entire circumference of the side wall 22. By configuring the side wall 22 in this manner, the strength of the side wall 22 can be improved.

[0037] The support portion 23 is a plate-like portion formed in a plate shape and has a support surface that supports the main surface of the pack 11 of the electricity storage device 10. The electricity storage device 10 is placed on the support surface of the support portion 23. Note that the support portion 23 and the pack 11 may be in contact with each other, but this is not limited thereto. For example, another sheet member may be inserted between the support portion 23 and the pack 11.

[0038] In the present embodiment, the case 20 holds two power storage devices 10, namely, a first power storage device 10a and a second power storage device 10b. Therefore, the case 20 has two storage sections 21. Specifically, the two storage sections 21 are provided at the top and bottom of the case 20. That is, one of the two storage sections 21 is provided on the bottom side of the case 20, and the other of the two storage sections 21 is provided on the top side of the case 20. Therefore, with respect to the two power storage devices 10 held in the case 20, one power storage device 10 (the first power storage device 10a) is disposed on the bottom side of the case 20, and the other power storage device 10 (the second power storage device 10b) is disposed on the top side of the case 20. In the present embodiment, the two storage sections 21 share a common support section 23, and the two power storage devices 10, namely, the first power storage device 10a and the second power storage device 10b, are disposed above and below each other via the support section 23. That is, the first power storage device 10 a and the second power storage device 10 b are arranged in the case 20 with the support portion 23 sandwiched between them.

[0039] The case 20 is made of an insulating resin material. In this embodiment, the case 20 is made of polybutylene terephthalate (PBT). The case 20 is a resin molded product formed integrally by injection molding. However, the insulating resin material that makes up the case 20 is not limited to PBT.

[0040] As shown in Figures 5 and 6, the case 20 is provided with a blade member 24 for opening a hole in the expanding portion of the pack 11 of the electricity storage device 10 when the pack 11 expands. Therefore, the blade member 24 has a shape that allows it to pierce the pack 11. Therefore, it is preferable that the blade member 24 has a sharp cutting edge at the tip. As shown in Figure 6, in this embodiment, the cross-sectional shape of the blade member 24 is a substantially triangular shape with an acute angle at the tip. As an example, the cross-sectional shape of the blade member 24 is a substantially isosceles triangle.

[0041] As shown in FIG. 10 , a groove 24a is formed on the side of the blade member 24, extending from the cutting edge side toward the base side of the blade member 24. FIG. 10 is a cross-sectional perspective view of the energy storage unit 1 according to the embodiment. In this embodiment, the groove 24a has a constant width and is formed from the center of the side of the blade member 24 to the base side. Furthermore, the side surfaces on both sides of the groove 24a of the blade member 24 are inclined surfaces that widen from the cutting edge side toward the base side of the blade member 24. Therefore, the depth of the groove 24a gradually increases from the cutting edge side toward the base side of the blade member 24. While the groove 24a is formed on each of both side surfaces of the blade member 24, it may be formed on only one of the side surfaces of the blade member 24. A base may be formed at the base portion of the blade member 24. For example, the base may be formed at the base of the side surface of the blade member 24. In this embodiment, the base of the blade member 24 is a grooved base in which a groove 24a is formed.

[0042] The blade member 24 is provided in the storage section 21 of the case 20. Specifically, the blade member 24 is provided in the support section 23 of the storage section 21. The blade member 24 is formed so as to protrude from the support surface of the support section 23.

[0043] The blade member 24 is provided at a position corresponding to one of the four sides of the side wall 22 other than the three sides that come into contact with the pack 11 when it is expanded. Specifically, the blade member 24 is provided at a position close to one of the two short sides of the side wall 22.

[0044] In the present embodiment, two power storage devices 10 are held in the case 20, and therefore two blade members 24 are provided in the case 20. That is, a blade member 24 is provided in each of the two storage sections 21. The two blade members 24 correspond one-to-one to the two power storage devices 10. Specifically, one of the two blade members 24 is provided for punching holes in the pack 11 of the first power storage device 10a, and the other of the two blade members 24 is provided for punching holes in the pack 11 of the second power storage device 10b. As shown in FIGS. 6 and 10 , the two blade members 24 are provided in positions that face each other vertically with the support section 23 in between.

[0045] The blade member 24 is made of an insulating material. Specifically, the blade member 24 is made of an insulating resin material. In this embodiment, the blade member 24 is a part of the case 20. Therefore, the blade member 24 is formed integrally with the case 20.

[0046] The electricity storage device 10 placed in the case 20 is covered with the internal cover 30 and fixed to the case 20. Specifically, the sealed portion 11a of the pack 11 of the electricity storage device 10 is sandwiched between the side wall 22 of the case 20 and the internal cover 30, and the case 20 and the internal cover 30 are fixed together with screws 71, thereby fixing the electricity storage device 10 to the case 20.

[0047] In the present embodiment, two power storage devices 10, a first power storage device 10a and a second power storage device 10b, are held in the case 20, and therefore two internal covers, a first internal cover 30a and a second internal cover 30b, are used as the internal covers 30. In this case, the first internal cover 30a covers the lower main surface of the first power storage device 10a, and the second internal cover 30b covers the upper main surface of the second power storage device 10b.

[0048] The first and second power storage devices 10a, 10b are held between the first and second inner covers 30a, 30b and the case 20. Specifically, the sealed portion 11a of the pack 11 of the first power storage device 10a is sandwiched between the lower side wall 22 of the case 20 and the first inner cover 30a, and the sealed portion 11a of the pack 11 of the second power storage device 10b is sandwiched between the upper side wall 22 of the case 20 and the second inner cover 30b. In this state, the first inner cover 30a, the case 20 and the second inner cover 30b are fastened together with screws 71, whereby the first and second power storage devices 10a, 10b can be held in the case 20.

[0049] This also makes it possible to obtain an energy storage module 2 that integrates two energy storage devices 10 (first energy storage device 10a and second energy storage device 10b), a case 20, and two internal covers 30 (first internal cover 30a and second internal cover 30b).

[0050] Each of the first inner cover 30a and the second inner cover 30b is provided with a locking claw 31 formed in a recess formed on the outer surface of the case 20. This allows the first inner cover 30a and the second inner cover 30b to be temporarily fastened to the case 20 before the first inner cover 30a and the second inner cover 30b are screwed to the case 20.

[0051] Since the electricity storage module 2 in this embodiment is thin, the vertical gap between the electricity storage device 10 and the inner cover 30 or the vertical gap between the electricity storage device 10 and the case 20 is narrowed. Specifically, the lower first electricity storage device 10a supported by the first inner cover 30a has a narrow gap between it and the support portion 23 of the case 20. Furthermore, the upper second electricity storage device 10b supported by the support portion 23 of the case 20 has a narrow gap between it and the second inner cover 30b.

[0052] Furthermore, in this embodiment, since the energy storage unit 1 is also thin, the gap between the energy storage module 2 and the circuit board 40 is also narrowed. Specifically, the gap between the circuit board 40 and the first inner cover 30a covering the underside of the first energy storage device 10a is narrowed, so that the circuit board 40 and the first inner cover 30a are brought closer together. As an example, the gap between the circuit board 40 and the first inner cover 30a is about 2 to 3 mm.

[0053] The first inner cover 30a and the second inner cover 30b are made of an insulating resin material. Each of the first inner cover 30a and the second inner cover 30b is a resin molded product integrally formed by injection molding. In this embodiment, the first inner cover 30a and the second inner cover 30b are made of different insulating resin materials. Specifically, the lower (circuit board 40 side) first inner cover 30a is made of polyphenylene sulfide (PPS), and the upper second inner cover 30b, like the case 20, is made of PBT. Furthermore, the rigidity of the first inner cover 30a is higher than the rigidity of the second inner cover 30b. This prevents deformation of the first inner cover 30a even when stress is applied to the first inner cover 30a. Note that the insulating resin materials used to make the first inner cover 30a and the second inner cover 30b are not limited to those described above. The first inner cover 30a and the second inner cover 30b may be made of the same insulating resin material.

[0054] The inner cover 30 and the circuit board 40 are covered by a housing 50. The housing 50 is an outer cover that covers the inner cover 30. In this embodiment, the housing 50 has a first outer cover 50a that covers the first inner cover 30a and a second outer cover 50b that covers the second inner cover 30b. In other words, the first outer cover 50a is a lower cover that covers the first inner cover 30a located below, and the second outer cover 50b is an upper cover that covers the second inner cover 30b located above.

[0055] A circuit board 40, on which electronic components are mounted, is disposed on the lower first outer cover 50a. The circuit board 40 is supported by the first outer cover 50a. The electronic components mounted on the circuit board 40 control, for example, charging and discharging of the power storage device 10.

[0056] The first outer cover 50a and the second outer cover 50b are metal covers made of a metal material. Specifically, the first outer cover 50a and the second outer cover 50b are made of sheet metal, such as aluminum alloy plate or steel plate. Specifically, the first outer cover 50a and the second outer cover 50b are press-molded products formed into a substantially box shape by applying roll forming and / or press working to a single metal plate. In this embodiment, the first outer cover 50a and the second outer cover 50b are both made of aluminum alloy plate.

[0057] The first outer cover 50a and the second outer cover 50b are formed in the shape of a rectangular box. Therefore, the top view of each of the first outer cover 50a and the second outer cover 50b is rectangular. The first outer cover 50a and the second outer cover 50b are fixed to each other with screws 73. Note that screws 71, which fasten the first inner cover 30a, the case 20, and the second inner cover 30b together, are threaded into screw holes in the first outer cover 50a.

[0058] As shown in FIG. 6 , the first outer cover 50a has a protrusion 51 that protrudes toward the circuit board 40. As shown in FIGS. 11 and 12 , the protrusion 51 is formed on the bottom of the first outer cover 50a. FIG. 11 is a perspective view of the first outer cover 50a viewed obliquely from above, and FIG. 12 is a perspective view of the first outer cover 50a viewed obliquely from below. Specifically, the protrusion 51 is formed so that a portion of the metal plate constituting the first outer cover 50a protrudes toward the circuit board 40. That is, the protrusion 51 is formed so as to protrude upward (inward). The protrusion 51 can be formed, for example, by drawing a metal plate. The protrusion 51 extends along the longitudinal direction of the first outer cover 50a. The planar shape of the protrusion 51 is an elongated racetrack shape. By providing the protrusion 51 in this manner, the rigidity of the first outer cover 50a can be increased.

[0059] The first outer cover 50a has a support pillar 80. The support pillar 80 protrudes from the bottom of the first outer cover 50a. The support pillar 80 loosely passes through a through hole 41 provided in the circuit board 40. That is, the support pillar 80 passes through the through hole 41 without contacting the circuit board 40, and a gap exists between the support pillar 80 and the inner surface of the through hole 41. Specifically, as shown in FIG. 6 , the support pillar 80 is provided so that it loosely passes through the through hole 41 of the circuit board 40 and its tip end is close to the first inner cover 30a. In this embodiment, before the power storage device 10 expands, a gap exists between the tip end of the support pillar 80 and the first inner cover 30a. As an example, the gap between the tip end of the support pillar 80 and the first inner cover 30a is approximately 1 mm.

[0060] 11 and 12, in this embodiment, the support pillars 80 are provided on the protruding portions 51 of the first outer cover 50a. That is, the support pillars 80 are provided so as to protrude from the protruding portions 51.

[0061] Furthermore, a plurality of support columns 80 are provided. The plurality of support columns 80 are arranged in a row along the longitudinal direction of the pack 11 of the electricity storage device 10, which has a rectangular shape in top view. All of the plurality of support columns 80 are provided on the protruding portion 51. In this case, the plurality of support columns 80 are arranged in a row along the longitudinal direction of the protruding portion 51.

[0062] 6, the circuit board 40 is provided with at least one through-hole 41 through which a support post 80 provided on the first outer cover 50a passes. In this embodiment, the first outer cover 50a is provided with a plurality of support posts 80, and therefore the circuit board 40 is provided with a plurality of through-holes 41.

[0063] The support pillars 80 are, for example, metal pins made of a metal material. The shape of the support pillars 80 is, for example, cylindrical. The support pillars 80 are fixed to the first outer cover 50a by being press-fitted into through-holes 52 formed in the first outer cover 50a. The support pillars 80 may have threaded portions such as clinching nuts or clinch bolts. In this case, the support pillars 80 are fixed to the first outer cover 50a by screwing the threaded portions into the through-holes 52 formed in the first outer cover 50a. In this embodiment, the multiple support pillars 80 all have the same shape and size and are all made of the same material, but this is not limited to this. The material of the support pillars 80 is not limited to a metal material. For example, the support pillars 80 may be made of a resin material or the like.

[0064] The first outer cover 50a is also provided with a connection socket 90. The connection socket 90 is provided with connection pins that are electrically connected to the wiring of the circuit board 40. A connector having conductive wires that is electrically connected to an external device is inserted into the connection socket 90. A bracket 100 for fixing the energy storage unit 1 to an external member is fixed to the rear surface of the first outer cover 50a.

[0065] Next, the effects of the energy storage unit 1 configured in this manner will be described with reference to Figures 13 to 16. Figures 13 and 14 are cross-sectional views of the energy storage unit 1 when the lower energy storage device 10 (first energy storage device 10a) is expanded, and Figures 15 and 16 are cross-sectional views of the energy storage unit 1 when the upper energy storage device 10 (second energy storage device 10b) is expanded. Figures 13 and 15 show cross sections of the energy storage unit 1 taken along the longitudinal direction, and Figures 14 and 16 show cross sections of the energy storage unit 1 taken along the lateral direction.

[0066] When the electricity storage device 10 is exposed to a high temperature environment or is overcharged, gas is generated within the pack 11 of the electricity storage device 10, causing the pack 11 to expand.

[0067] 13 and 14 , when the pack 11 of the lower first electricity storage device 10a expands, the pack 11 of the first electricity storage device 10a expands in all directions, but in this embodiment, the first electricity storage device 10a is arranged in the narrow space between the first inner cover 30a and the case 20. For this reason, the pack 11 of the first electricity storage device 10a expands toward the blade member 24 while being restricted by the first inner cover 30a and the case 20.

[0068] Specifically, the support portions 23 of the case 20 and the first inner cover 30a are present in the up-down direction of the first electricity storage device 10a, and the side walls 22 of the case 20 are present on the sides of the first electricity storage device 10a. Therefore, when the pack 11 of the first electricity storage device 10a expands, the upper and lower portions of the pack 11 are pressed down by the first inner cover 30a and the support portions 23 of the case 20. In other words, the expansion of the pack 11 of the first electricity storage device 10a in the up-down direction is restricted by the first inner cover 30a and the support portions 23 of the case 20. As a result, the pack 11 of the first electricity storage device 10a expands in the lateral direction (horizontal direction).

[0069] At this time, since the first energy storage device 10a is surrounded by the side wall 22, when the pack 11 of the first energy storage device 10a expands laterally, the outer peripheral portion of the pack 11 abuts against the side wall 22, thereby restricting the expansion in the lateral direction.

[0070] In this embodiment, the portion of the two short sides of the side wall 22 of the case 20 that faces the short side on the terminal 13 side of the pack 11 is farther away from the side surface of the pack 11 than the portions corresponding to the two long sides and the other short sides of the side wall 22. Therefore, when the pack 11 expands laterally, the outer periphery of the pack 11 that corresponds to the short side opposite the short side on the terminal 13 side and the two long sides abuts against the side wall 22 before the outer periphery of the pack 11 that corresponds to the short side on the terminal 13 side abuts against the side wall 22. In other words, the case 20 and the first inner cover 30a are structured so that the outer periphery of the pack 11 of the first electricity storage device 10a that corresponds to the short side on the terminal 13 side of the pack 11 promotes expansion compared to the other portions. As a result, the pack 11 of the first electricity storage device 10a expands toward the blade member 24 provided corresponding to the short side on the terminal 13 side of the pack 11.

[0071] When the expanding portion of the pack 11 of the first electricity storage device 10a reaches the blade member 24, the blade member 24 pierces the expanding portion of the pack 11, creating a hole in the pack 11. Specifically, the reaction force generated when the pack 11 pushes the blade member 24 due to expansion causes the tip of the blade member 24 to break through the pack 11, creating a hole in the pack 11. Note that because the first electricity storage device 10a is located on the lower side, the portion of the pack 11 of the first electricity storage device 10a that is to be perforated by the blade member 24 is the upper surface of the pack 11. By thus positioning the portion that is perforated by the blade member 24 on the upper surface of the pack 11, it is possible to prevent the electrolyte in the pack 11 from leaking out, and to prevent secondary damage, etc.

[0072] In the present embodiment, the energy storage module 2 has a thin structure, so the gap in the vertical direction between the first energy storage device 10a and the case 20 is narrow. Furthermore, the energy storage unit 1 also has a thin structure, so the gap between the energy storage module 2 and the circuit board 40 is also narrow. Specifically, the gap between the first inner cover 30a covering the underside of the first energy storage device 10a and the circuit board 40 is narrowed, so that the circuit board 40 and the first inner cover 30a are close to each other.

[0073] Therefore, when the pack 11 of the first electricity storage device 10a expands, the expanding pack 11 presses against the first inner cover 30a. As a result, as shown in Figures 13 and 14, the first inner cover 30a is curved so as to be convex toward the circuit board 40 (bottom side).

[0074] At this time, the first outer cover 50a is provided with support posts 80 that penetrate the through holes 41 of the circuit board 40. As a result, the first inner cover 30a, which attempts to bend toward the circuit board 40, is supported by the support posts 80. Furthermore, because the support posts 80 are provided on the first outer cover 50a rather than on the circuit board 40, even if the bending first inner cover 30a presses against the support posts 80, no stress is applied to the circuit board 40. In other words, even if the tip of the support posts 80 moves downward due to the pressure of the bending first inner cover 30a, the support posts 80 simply move within the through holes 41 of the circuit board 40 without coming into contact with the circuit board 40. In this way, by supporting the first inner cover 30a, which attempts to bend, with the support posts 80, the first inner cover 30a can be prevented from bending significantly. As a result, even if the first inner cover 30a bends, it is possible to prevent the first inner cover 30a from coming into contact with the circuit board 40 or electronic components on the circuit board 40.

[0075] This prevents the curved first inner cover 30a from coming into contact with the circuit board 40 or the electronic components on the circuit board 40, causing the circuits on the circuit board 40 to malfunction. It also prevents the circuit board 40 from warping or the electronic components from being damaged, which would otherwise reduce the reliability of the energy storage unit 1.

[0076] Next, a case where the pack 11 of the upper second electricity storage device 10b expands will be described with reference to FIGS. 15 and 16. FIG.

[0077] As shown in FIGS. 15 and 16, when the pack 11 of the second electricity storage device 10b expands, holes are made in the pack 11 of the second electricity storage device 10b by the blade members 24, similar to the pack 11 of the first electricity storage device 10a.

[0078] At this time, the pack 11 of the second energy storage device 10b is positioned in the narrow space between the second inner cover 30b and the case 20, and therefore, like the pack 11 of the first energy storage device 10a, it expands toward the blade member 24 while being restricted by the second inner cover 30b and the case 20.

[0079] Specifically, the support portions 23 of the case 20 and the second inner cover 30b are present in the vertical direction of the second electricity storage device 10b, and the side walls 22 of the case 20 are present on the sides of the second electricity storage device 10b. Therefore, when the pack 11 of the second electricity storage device 10b expands, the upper and lower portions of the pack 11 are pressed down by the second inner cover 30b and the support portions 23 of the case 20. In other words, the expansion of the pack 11 of the second electricity storage device 10b in the vertical direction is restricted by the second inner cover 30b and the support portions 23 of the case 20. As a result, the pack 11 of the second electricity storage device 10b also expands in the lateral direction (horizontal direction).

[0080] At this time, since the second energy storage device 10b is surrounded by the side wall 22, when the pack 11 of the second energy storage device 10b expands laterally, the outer peripheral portion of the pack 11 abuts against the side wall 22, thereby restricting the expansion in the lateral direction.

[0081] In this case, like the lower sidewall 22, the upper sidewall 22 of the case 20 has a portion of its two short sides facing the short side on the terminal 13 side of the pack 11 that is farther away from the side surface of the pack 11 than the portions corresponding to the two long sides and the other short sides of the sidewall 22. Therefore, when the pack 11 of the second electricity storage device 10b expands laterally, the outer peripheral portion corresponding to the short side opposite the short side on the terminal 13 side and the two long sides abuts against the sidewall 22 before the outer peripheral portion corresponding to the short side on the terminal 13 side abuts against the sidewall 22, thereby restricting the pack 11's expansion in the lateral direction. In other words, the case 20 and the second inner cover 30b are structured to promote expansion of the outer peripheral portion of the pack 11 of the second electricity storage device 10b that corresponds to the short side on the terminal 13 side compared to the other portions. As a result, the pack 11 of the second electricity storage device 10b expands toward the blade member 24 provided corresponding to the short side on the terminal 13 side of the pack 11.

[0082] Then, when the expanding portion of the pack 11 of the second electricity storage device 10b reaches the blade member 24, the blade member 24 pierces the expanding portion of the pack 11, similar to the pack 11 of the first electricity storage device 10a, and a hole is made in the pack 11. Note that, because the second electricity storage device 10b is located on the upper side, the portion of the pack 11 of the second electricity storage device 10b that is made a hole by the blade member 24 is the lower surface of the pack 11.

[0083] In this way, according to the energy storage unit 1 of this embodiment, when the pack 11 of the energy storage device 10 expands, the blade member 24 can pierce the expanded portion of the pack 11 and make a hole in the pack 11.

[0084] At this time, in the energy storage unit 1 and the energy storage module 2 according to this embodiment, the blade members 24 are provided on the case 20, and the blade members 24 are made of an insulating material.

[0085] As a result, even if the blade member 24 comes into contact with the electrode stack 12, the blade member 24 is made of an insulating material, so it is possible to prevent the electrode stack 12 from shorting out at the blade member 24. Furthermore, because the blade member 24 is made of an insulating material, there is no effect even if the blade member 24 comes into contact with the electrolyte inside the pack 11 when a hole is drilled in the pack 11. Moreover, because the blade member 24 is provided in the case 20, explosion-proof measures for the electricity storage device 10 can be implemented at low cost.

[0086] Moreover, a groove 24 a extending from the cutting edge side of the blade member 24 toward the base side is formed on the side surface of the blade member 24 that pierces the pack 11 .

[0087] With this configuration, when the blade member 24 pierces the pack 11 of the electricity storage device 10, a gap (gas vent gap) for releasing gas inside the pack 11 can be always secured between the pack 11 and the blade member 24. In other words, the groove 24a provided in the blade member 24 functions as a gas vent gap. This makes it possible to prevent a gap from being formed between the pack 11 and the blade member 24 pierced into the pack 11 when, for example, the pressure caused by the expansion of the pack 11 is large. In other words, even when the pressure caused by the expansion of the pack 11 is large, a gap can always be secured between the pack 11 and the blade member 24 pierced into the pack 11. This allows gas inside the pack 11 to be stably discharged when the blade member 24 pierces the pack 11.

[0088] As described above, according to the energy storage unit 1 and the energy storage module 2 of this embodiment, when the pack 11 of the energy storage device 10 expands, holes can be drilled in the pack 11 of the energy storage device 10 to stably release the gas inside the pack 11 without short-circuiting the electrode stack 12 of the energy storage device 10 and without incurring any costs. This makes it possible to prevent the pack 11 from expanding and bursting.

[0089] In the above embodiment, the cases where only the pack 11 of the lower first electricity storage device 10a expands (Figures 13 and 14) and the cases where only the pack 11 of the upper second electricity storage device 10b expands (Figures 15 and 16) have been described separately, but there are also cases where the pack 11 of the first electricity storage device 10a and the pack 11 of the second electricity storage device 10b expand simultaneously.

[0090] In the energy storage unit 1 and the energy storage module 2 according to this embodiment, the blade member 24 is part of the case 20 made of an insulating resin material.

[0091] This configuration allows the blade member 24 and the case 20 to be integrally formed. This eliminates the need for a process of separately manufacturing the blade member 24 or separately attaching the blade member 24 to the case 20, making it possible to manufacture the energy storage unit 1 and the energy storage module 2 at even lower cost.

[0092] In this embodiment, a base is further formed at the base of the blade member 24. This prevents the pierced pack 11 from adhering tightly to the support portion 23, which would otherwise eliminate any gap, and allows gas to be discharged stably.

[0093] Furthermore, in the energy storage unit 1 and energy storage module 2 according to this embodiment, the pack 11 of the energy storage device 10 has a rectangular shape when viewed from above, the case 20 has side walls 22 that abut against the side surfaces of three of the four sides of the pack 11 when the pack 11 expands, and the blade member 24 is provided at a position corresponding to the side surface of one of the four sides of the pack 11 other than the three sides.

[0094] With this configuration, when the pack 11 of the electricity storage device 10 expands, the lateral expansion of the pack 11 is restricted by the side wall 22 of the case 20. Specifically, the side wall 22 of the case 20 allows the pack 11 to expand toward the blade member 24 provided at a position corresponding to the side surface of one of the four sides of the pack 11 other than three of the four sides. In other words, the side wall 22 of the case 20 functions as a guide portion that guides the pack 11 to expand toward the blade member 24. This allows the pack 11 of the electricity storage device 10 to expand at a targeted position and be pressed firmly against the blade member 24, so that holes can be effectively drilled in the pack 11 even if the blade member 24 is made of resin rather than metal.

[0095] Furthermore, in the energy storage unit 1 and the energy storage module 2 according to this embodiment, the inner cover 30 is provided, which comes into contact with one main surface of the pack 11 of the energy storage device 10 when the pack 11 expands, and the case 20 supports the other main surface of the pack 11. In other words, the pack 11 is disposed between the inner cover 30 and the case 20.

[0096] With this configuration, when the pack 11 of the electricity storage device 10 expands, the expansion of the pack 11 in the vertical direction is restricted by the case 20 and the internal cover 30. Specifically, the support portion 23 of the case 20 and the internal cover 30 suppress the expansion of the pack 11 in the vertical direction, thereby encouraging the pack 11 to expand in the lateral direction. This allows the pack 11 to expand toward the blade member 24 arranged on the side of the pack 11. In other words, the support portion 23 of the case 20 and the internal cover 30 function as guide portions that guide the pack 11 to expand toward the blade member 24. This allows the pack 11 of the electricity storage device 10 to expand at a targeted position and be pressed firmly against the blade member 24, so that holes can be effectively drilled in the pack 11 even if the blade member 24 is made of resin rather than metal.

[0097] (Modifications) Although the technology of the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above-described embodiments.

[0098] For example, in the energy storage unit 1 according to the above embodiment, the cross-sectional shape of the blade member 24 is a substantially isosceles triangle, but this is not limiting. For example, as in the energy storage unit 1A shown in FIG. 17 , the cross-sectional shape of the blade member 24A of the case 20A may be a right-angled triangle. In this case, the blade member 24A may be formed on the case 20A so that the right-angled portion faces the energy storage device 10. Furthermore, as in the energy storage unit 1B shown in FIG. 18 , the tip of the blade member 24B of the case 20B may be provided with a sharp protrusion 24b that protrudes toward the energy storage device 10. This allows the protrusion 24b of the blade member 24B to more easily pierce the expanded pack 11 than a blade member 24 without the protrusion 24b.

[0099] In the above embodiment, the power storage device 10 is a lithium ion capacitor, but this is not limiting. The power storage device 10 may be a capacitor other than a lithium ion capacitor. Furthermore, the power storage device 10 is not limited to a capacitor, and may be a secondary battery such as a lithium ion secondary battery.

[0100] In the above embodiment, the power storage unit 1 includes two power storage devices 10, but this is not limiting. The power storage unit 1 may include one power storage device 10, or may include more than two power storage devices 10.

[0101] In the above embodiment, the support posts 80 provided on the first outer cover 50a are metal pins, but this is not limiting. For example, the support posts 80 may be formed by deforming the metal plate that constitutes the first outer cover 50a by drawing or the like. This eliminates the need for metal pins, thereby reducing costs.

[0102] In the above embodiment, the power storage unit 1 is used in an automobile, but the present invention is not limited to this. For example, the power storage unit 1 can also be applied to electrical appliances and the like.

[0103] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that would occur to those skilled in the art, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. Furthermore, the present disclosure also includes any combination of two or more claims from among the multiple claims set forth in the claims at the time of filing, within the scope of technical compatibility. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of technical compatibility, the present disclosure also includes all combinations of claims included in that multiple claim or multiple multiple multiple claims.

[0104] The technology of the present disclosure can be widely used in various products such as automobiles or electrical appliances.

[0105] REFERENCE SIGNS LIST 1, 1A, 1B Energy storage unit 2 Energy storage module 10 Energy storage device 10a First energy storage device 10b Second energy storage device 11 Pack 11a Sealing portion 12 Electrode stack 13 Terminal 20, 20A, 20B Case 21 Storage portion 22 Side wall 22a Inner wall 22b Outer wall 22c Connection wall 23 Support portion 24, 24A, 24B Blade member 24a Groove 24b Protrusion 30 Inner cover 30a First inner cover 30b Second inner cover 31 Locking claw 40 Circuit board 41 Through hole 50 Housing 50a First outer cover 50b Second outer cover 51 Protrusion 52 Through hole 60 Bus bar 71, 72, 73 Screw 80 Support 90 Connection socket 100 bracket

Claims

1. An energy storage module comprising: an energy storage device having a pack made of a laminate film and an electrode stack contained in the pack; a case for holding the energy storage device; and a blade member provided on the case for opening a hole in an expanding portion of the pack when the pack expands, the blade member being made of an insulating material, and a groove extending from the cutting edge side to the base side of the blade member being formed on a side surface of the blade member.

2. The energy storage module according to claim 1, wherein the case is made of an insulating resin material, and the blade member is a part of the case.

3. The energy storage module according to claim 1 or 2, wherein a grooved seat is formed at the base of a side surface of the blade member.

4. The energy storage module according to claim 1 or 2, wherein the pack has a rectangular shape when viewed from above, the case has side walls that abut against the side surfaces of three of the four sides of the pack when or before the pack expands, and the blade member is provided at a position corresponding to the side surface of one of the four sides other than the three sides.

5. The energy storage module according to claim 4, further comprising a cover that abuts against one main surface of the pack when or before the pack expands, and the case supports the other main surface of the pack.

6. The energy storage module according to claim 1 or 2, wherein the pack is hermetically sealed by heat sealing the laminate film along the outer periphery of the pack, and the energy storage device has a pair of terminals extending from the pack.

7. The energy storage module according to claim 1 or 2, wherein the energy storage device is a lithium ion capacitor.

8. An energy storage unit comprising: the energy storage module according to claim 1 or 2; a circuit board on which electronic components for controlling an energy storage device in the energy storage module are mounted; and a housing for accommodating the energy storage module and the circuit board.

Images