Energy storage pack

Abstract

To provide a battery pack with high safety, capable of suppressing a rapid rise of an internal pressure in the battery pack.SOLUTION: A battery pack comprises: a plurality of power storage devices electrically connected with each other; a main body part of a closed outer casing that houses the plurality of power storage devices; and a development member that, when the pressure inside the outer casing increases and exceeds a predetermined value, increases the internal capacity of the outer casing.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an electricity storage pack. [Background technology]

[0002] Energy storage packs are preferably used as high-output power sources, particularly as battery packs for vehicles. Such energy storage packs include a plurality of connected energy storage devices and an exterior housing that houses the energy storage devices. The energy storage devices use energy storage elements such as lithium-ion secondary batteries, nickel-metal hydride batteries, and other secondary batteries or capacitors, which are lightweight and provide high energy density. Since this type of energy storage pack is typically mounted outside the passenger compartment of a vehicle, a highly rigid, airtight exterior housing is used. However, if a major malfunction occurs in the energy storage device and unexpected gas is generated, the pressure inside the exterior housing may suddenly increase, potentially damaging the exterior housing.

[0003] Patent Document 1 discloses a battery pack containing multiple battery cells. An expansion space is provided inside the battery pack. High-temperature gas ejected from the exhaust valve of each battery cell collides with the collision plate of the flame-retardant cap and is temporarily retained in the expansion space through the diffusion gap and the back-ejection gap, where it is attenuated. This prevents the gas from being forcefully ejected outside the battery pack. The high-temperature gas that fills the expansion space is then dispersed through multiple smoke exhaust holes and discharged outside the battery pack.

[0004] Patent Document 2 discloses a pouch-type battery case in which an upper battery case and a lower battery case, each having a foldable structure and space corners, are heat-sealed at their sealing portions. When gas is generated inside the battery and the internal pressure of the battery increases, the foldable structure of the pouch-type battery case unfolds toward the electrodes, separating the electrode tabs and electrode leads from the electrode assembly and interrupting the current. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 153015 [Patent Document 2] Special Publication No. 2013-535791 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the technology described in Patent Document 1, gas generated from the battery cell passes through thin tubular diffusion gaps and reverse ejection gaps while colliding with each other before entering the expansion space. This increases the flow resistance of the gas before it is released to the outside, which may prevent the gas from being completely discharged through the smoke exhaust hole, resulting in damage to the battery pack. Furthermore, with the technology described in Patent Document 2, a folding structure (expansion section) is formed in the direction in which the electrode leads protrude, so when internal pressure increases, pressure concentrates at the sealing section. This may result in the battery case tearing and being damaged at the sealing section.

[0007] Therefore, an object of the present disclosure is to provide a highly safe electricity storage pack that is capable of suppressing damage to the electricity storage pack due to a sudden increase in internal pressure within the electricity storage pack. [Means for solving the problem]

[0008] The energy storage pack disclosed herein includes a plurality of energy storage devices electrically connected to each other, and an exterior body that houses the plurality of energy storage devices in a sealed state, wherein the exterior body includes an expansion member that expands when the internal pressure of the exterior body increases, thereby increasing the internal volume of the exterior body.

[0009] In this electricity storage pack, the deployment member deploys when gas is generated, increasing the internal volume of the exterior body. This temporarily suppresses a momentary increase in internal pressure of the electricity storage pack, thereby preventing damage to the electricity storage pack.

[0010] In one aspect of the electricity storage pack disclosed herein, the exterior body includes a main body that is a box-shaped rigid member that houses the electricity storage device and a vent hole provided in a bottom surface of the main body, and the deployment member includes a protective portion that is a plate-shaped rigid member that faces the bottom surface of the main body, and a deployment portion that is a flexible member that connects the periphery of the bottom surface of the main body and the protective portion so as to seal the exterior body. This makes it possible to protect the deployment portion before the internal pressure of the exterior body increases.

[0011] In one aspect of the electricity storage pack disclosed herein, the protective part has a peripheral wall part on its outer periphery that protrudes toward the bottom surface of the main body part, and the unfolding part is housed in a space surrounded by the protective part and the bottom surface of the main body part in a folded state, thereby making it possible to more appropriately protect the unfolding part before the internal pressure of the exterior body increases.

[0012] In one aspect of the electricity storage pack disclosed herein, the exterior body includes a stopper that restricts deployment of the deployment member, and the stopper is a rod-shaped member that connects the main body and the protective part, and releases the connection between the main body and the protective part when the internal pressure of the exterior body exceeds a predetermined value. This allows the electricity storage pack to be made compact, thereby saving space when the electricity storage pack is housed in a device.

[0013] The electricity storage pack of one aspect disclosed herein includes a sensor that detects the deployment of the deployment member. This makes it possible to detect the deployment of the deployment member, i.e., the increase in internal pressure of the electricity storage pack, based on a detection signal from the detection sensor.

[0014] In one aspect of the vehicle disclosed herein, the power storage pack is mounted on the vehicle such that the deployment member deploys to the underside of the vehicle, thereby enabling the deployment member to be operated safely while ensuring passenger space. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a cross-sectional view schematically illustrating the internal structure of the electricity storage pack of the embodiment before deployment. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating the internal structure of the electricity storage pack of the embodiment after it is unfolded. [Figure 3] FIG. 2 is an enlarged view of a main part of the electricity storage pack according to the embodiment before deployment. [Figure 4] FIG. 2 is an enlarged view of a main part of the electricity storage pack according to the embodiment after it is unfolded. [Figure 5] FIG. 10 is an enlarged view of a main part of an electricity storage pack according to another embodiment before deployment. [Figure 6] FIG. 10 is an enlarged view of a main part of an electricity storage pack according to another embodiment after it has been unfolded. [Figure 7] FIG. 2 is a diagram schematically illustrating a normal state of an electric vehicle equipped with a power storage pack. [Figure 8] FIG. 10 is a diagram schematically illustrating a state after deployment of deployment members in an electric vehicle equipped with an electricity storage pack. [Figure 9] FIG. 10 is a cross-sectional view schematically showing the internal structure of an electricity storage pack according to another embodiment before it is deployed. [Figure 10] FIG. 10 is a cross-sectional view schematically showing the internal structure of an electricity storage pack according to another embodiment after it is unfolded. DETAILED DESCRIPTION OF THE INVENTION

[0016] A typical embodiment of the present disclosure will be described in detail below with reference to the drawings. Matters necessary for implementation other than those specifically mentioned in this specification can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present disclosure can be implemented based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. In the following drawings, components and parts that perform the same function are denoted by the same reference numerals. Furthermore, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships.

[0017] In this specification, the term "electricity storage device" refers to a device that can be charged and discharged. Electricity storage devices include batteries such as secondary batteries (e.g., lithium-ion secondary batteries, nickel-metal hydride batteries) and capacitors (physical batteries) such as electric double-layer capacitors. Below, an electricity storage pack according to the present disclosure will be described in detail, taking as an example an electricity storage pack in which multiple electricity storage devices are housed in a container. However, it is not intended that the electricity storage pack according to the present disclosure be limited to those described in the following embodiments.

[0018] <Energy storage pack> FIG. 1 is a cross-sectional view schematically showing the internal structure of an electricity storage pack according to this embodiment. FIG. 2 is a cross-sectional view schematically showing the internal structure of the electricity storage pack according to this embodiment after it has been unfolded. FIG. 3 is an enlarged view of a main part of the electricity storage pack according to this embodiment before it is unfolded. FIG. 4 is an enlarged view of a main part of the electricity storage pack according to this embodiment after it has been unfolded. In the following description, the symbols L, R, U, and D in the drawings represent left, right, top, and bottom. However, these directions are merely provided for the convenience of description, and do not limit the installation form of the electricity storage pack in any way.

[0019] As shown in FIG. 1, an electricity storage pack 1 according to one embodiment is an electricity storage pack including an electricity storage device 10 and an exterior body 20.

[0020] <Electricity storage device> The electricity storage pack according to this embodiment includes a plurality of electricity storage devices 10 electrically connected to one another. In FIG. 1 , the plurality of electricity storage devices 10 are connected in series. However, the number and arrangement of the electricity storage devices are not limited to this in this embodiment. The electricity storage devices 10 are each shaped like a rectangular parallelepiped, i.e., a flattened square. Here, the plurality of electricity storage devices 10 are arranged in a row in the left-right direction so that a pair of flat surfaces face each other. However, the shape of the electricity storage device is not limited to this and may be, for example, a cylindrical shape. Each electricity storage device 10 houses an electrode assembly (not shown) therein and has electrode terminals (not shown) electrically connected to the electrode assembly and extending to the outside of the electricity storage device 10. Furthermore, a positive terminal (not shown) of one adjacent electricity storage device 10 and a negative terminal (not shown) of the other adjacent electricity storage device 10 are electrically connected to each other by a metal bus bar 15. Although not shown here, the plurality of electricity storage devices 10 are integrally held and fixed by a restraining band. The power storage devices 10 located at both ends in the left-right direction each have an external connection electrode terminal 16. The external connection electrode terminals 16 penetrate the exterior body 20 to the outside.

[0021] <Exterior body> The exterior body 20 houses a plurality of electricity storage devices 10 inside in a sealed state. In FIG. 1 , the exterior body 20 is a rectangular parallelepiped housing. The exterior body 20 is sealed with the electricity storage devices 10 housed inside. However, the shape and size of the exterior body 20 may be changed as appropriate depending on, for example, the size and number of electricity storage devices 10 to be housed.

[0022] Here, the exterior body 20 in this embodiment includes a main body 21, a vent 22, and a deployment member 23. Each component will be described below.

[0023] <Main body> The main body 21 is a box-shaped rigid member that houses the electricity storage device 10. Here, the outer shape of the main body 21 of the exterior body 20 is a rectangular box shape. The material of the main body 21 is not particularly limited as long as it has enough rigidity to protect the electricity storage device 10 from external impacts, dust, etc. Examples of the material of the main body 21 include metal and resin. Furthermore, the shape and size of the main body of the exterior body are not particularly limited and can be changed as appropriate.

[0024] <Ventilation hole> The ventilation opening 22 is an opening provided on the bottom surface of the main body 21 of the exterior body 20. The ventilation opening 22 allows gas generated from the electricity storage device 10 to flow into the deployment member 23 in the main body 21 of the exterior body 20. In the present embodiment, the shape, size, and number of the ventilation openings are not particularly limited. From the viewpoint of efficiently dispersing gas generated from the electricity storage device 10 inside the deployment member 23, it is preferable to have multiple ventilation openings 22. Furthermore, having a large number of ventilation openings 22 has the advantage of reducing the weight of the exterior body 20. By making the ventilation opening 22 mesh-shaped, it is possible to prevent fragments and debris from being introduced into the deployment member 23 when the electricity storage device 10 is damaged. This makes it possible to prevent the deployment portion 24 from being damaged from the inside.

[0025] <Deployment parts> The deployment member 23 is a member having a mechanism that deploys when the internal pressure of the exterior body 20 increases, thereby increasing the internal volume of the exterior body 20. As shown in FIGS. 1 and 2 , the deployment member 23 in this embodiment is joined to the bottom side surface of the main body 21. The interior of the main body 21 and the interior of the deployment member 23 are in communication with each other via at least one or more ventilation holes 22. This allows gas generated from the electricity storage device 10 to flow into the deployment member 23. In other words, the interior of the deployment member 23 forms a space that can be filled with gas.

[0026] Here, the deployment member 23 is formed by a deployment portion 24, a protection portion 25, and a stopper 26. Each component will be described below.

[0027] <Development section> The deployment section 24 is a flexible member that connects the bottom surface of the main body 21 and the periphery of the protective section 25. The deployment section 24 is hollow and rectangular or tubular. As shown in FIG. 3 , under normal conditions, the deployment section 24 is stored within the protective section 25 in a bellows-like folded state at least once. The deployment section 24 is configured to expand and deploy when the internal pressure increases. This allows the volume of the exterior body 20 to be increased. The material of the deployment section is preferably airtight and flexible, and has heat and pressure resistance. Specific examples of the material of the deployment section include polyamide, polyester, polyolefin, polyacetal, polysulfone, polyphenylene sulfide, polyether ether ketone, polyimide, polyetherimide, polyparaphenylene benzobisoxazole, vinylon, acrylic, cellulose, etc., and may contain fluorine, inorganic fillers, etc. Among these, polyester is preferred from the viewpoint of strength, and polyamide is more preferred.

[0028] 3 and 4, the deployment portion 24 is fixed to the bottom surface of the main body portion 21 of the exterior body 20 by a fixing member 27 such as a rivet. Here, the joint between the deployment portion 24 and the protective portion 25 is also similarly fixed by a fixing member 27. The joints between the main body portion, deployment portion, and protective portion may be joined by an adhesive.

[0029] <Protection Department> The protective portion 25 is a plate-like rigid member facing the bottom surface of the main body portion 21. The protective portion 25 covers the unfolding portion 24 and protects the flexible unfolding portion 24. In FIG. 3, the protective portion 25 stores the unfolding portion 24 in a normal state and protects it from external impacts, dust, and the like. Here, the protective portion 25 further has a peripheral wall portion 25a formed on the outer periphery thereof that protrudes toward the bottom surface of the main body portion 21 of the exterior body 20. This creates a space surrounded by the protective portion 25 and the bottom surface of the main body portion 21. This allows the unfolding portion 24 in a folded state to be stored in the space. The material of the protective portion is metal or resin, similar to that of the main body portion 21 of the exterior body 20.

[0030] <Stopper> The stopper 26 connects the main body 21 and the protective part 25 and restricts the deployment of the deployment member 23. The stopper 26 shown in FIGS. 3 and 4 is a metal or resin rivet or the like. In FIG. 3, the stopper 26 is a rivet formed with a rod-shaped body and a head part having a diameter larger than that of the body. Here, the stopper 26 connects the main body 21 and the protective part 25 so that they do not separate. As shown in FIG. 4, the stopper 26 breaks when the internal pressure of the exterior body 20 exceeds a predetermined value. This releases the restriction on the deployment of the deployment member 23. However, the stopper 26 is not limited to this. Removable stoppers such as button snaps, buckles, and hook-and-loop fasteners can also be selected. The type, material, and number of stoppers can also be changed so that the restriction of the stopper 26 is released when the pressure exceeds a predetermined value. If the stopper is a rivet, the body may be notched to make it easier to break. The stopper is not limited to the rivet having the above configuration, and an adhesive that peels off when a predetermined stress is applied can also be used.

[0031] <Expansion operation> As shown in FIG. 3 , in the normal state, i.e., when the internal pressure of the exterior body 20 is equal to or lower than a predetermined value, the stopper 26 secures the main body 21 of the exterior body 20 and the protective portion 25 of the deployment member 23. This prevents the deployment portion 24 from deploying regardless of an increase in internal pressure. The "predetermined value" here is, for example, approximately 0.035 MPa. By setting the pressure at which the deployment portion 24 deploys to this pressure, it is possible to prevent the stopper from accidentally releasing its restriction due to vibrations or the like in the normal state. The "predetermined value" can be increased or decreased as appropriate, taking into account the strength of the exterior body 20 and its volume in the normal state.

[0032] In the electricity storage pack 1 according to this embodiment, when unexpected gas is generated in the electricity storage device 10 and the internal pressure of the main body 21 of the exterior body 20 suddenly increases, the internal pressure of the deployment member 23 also increases via the ventilation hole 22. Next, the protective portion 25 is pushed outward from the exterior body 20, applying a tensile force to the stopper 26. When the pressure inside the exterior body 20 exceeds the predetermined value, the stopper 26 breaks, and the deployment member 23 is released from restriction. This causes the deployment portion 24 to deploy, instantly increasing the internal volume of the exterior body 20. This temporarily reduces the internal pressure of the exterior body 20 and prevents damage to the exterior body 20. Furthermore, the electricity storage pack 1 configured as described above has the advantage of eliminating the need to reserve a volume for gas filling in the exterior body 20 in advance, thereby allowing other space in the device incorporating the electricity storage pack 1 to be efficiently utilized. Preferably, the volume of the exterior body 20 after the deployment member 23 is finally double or more the volume of the exterior body 20 before deployment. This alleviates the momentary increase in pressure, and the internal pressure can be reduced before the exterior body 20 is damaged.

[0033] <Other embodiments> Although the preferred embodiments of the present disclosure have been described above with reference to the drawings, such descriptions are not limiting and various modifications are possible.

[0034] <Sensor installation> Another aspect of the electricity storage pack disclosed herein includes a sensor 40 that detects deployment of the deployment member 23. As shown in FIG. 5, the sensor is attached in a normal state, spanning the protective portion 25 (peripheral wall portion 25a in FIG. 5) of the deployment member 23 and the main body portion 21 of the exterior body 20. As shown in FIG. 6, when the internal pressure of the exterior body 20 exceeds a predetermined value, the stopper 26 breaks and the deployment member 23 is deployed. At this time, the sensor 40 becomes non-contact, thereby making it possible to detect that the deployment member 23 has been deployed. The detection means of the sensor 40 is not particularly limited, and in addition to the contact sensor described above, mechanical detection means, electrical detection means, etc. may be used as appropriate.

[0035] <Installation in a vehicle> In a preferred embodiment of the electricity storage pack disclosed herein, the electricity storage pack 1 is mounted on an electric vehicle 50 as a motor drive source. As shown in FIGS. 7 and 8 , the electricity storage pack 1 is installed under the floor of a vehicle body 55, and the deployment member 23 is fixed so as to deploy to the bottom side of the vehicle body. However, this does not limit the installation mode of the electricity storage pack 1 or the like, and does not limit the present disclosure in any way. The type of vehicle is not particularly limited, and examples include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV).

[0036] In the above embodiment, when gas is generated from the electricity storage device 10 due to a short circuit or the like, the internal pressure of the electricity storage pack 1 increases, and when the internal pressure exceeds a predetermined value, the deployment member 23 is deployed between the floor surface of the vehicle body 55 and the ground (not shown). This makes it possible to secure space after deployment of the deployment member 23 without encroaching on the passenger space.

[0037] In the embodiment disclosed herein, the electric vehicle 50 may include an electronic control unit (ECU) 60 and a display device 70. The ECU 60 is preferably connected to the sensor 40 (see FIG. 4).

[0038] The ECU 60 performs a predetermined function in accordance with, for example, a predetermined program. Here, the ECU 60 receives a signal from the sensor 40 that detects that the deployment member 23 of the electricity storage pack 1 is in the deployed state. The display device 70 is controlled by the ECU 60 and notifies the occupant that the deployment member 23 has been deployed. This allows the occupant to recognize that an abnormality has occurred in the battery pack, and enables the occupant to quickly ensure safety.

[0039] <Joint position of deployment members> In the above embodiment, the deployment member 23 is joined to the bottom side surface of the exterior body 20. However, this is not limiting, and the deployment member may be joined to the side surface or top surface via a ventilation hole. It is also preferable to provide multiple deployment members 23 and deploy them in stages. This makes it possible to more reliably mitigate a sudden increase in internal pressure. This is particularly effective when a chain reaction of short circuits occurs in the electricity storage device.

[0040] <With or without stopper> 3 to 6, in the above embodiment, the deployment member 23 is provided with a stopper 26 that restricts deployment. However, this is not limited to this, and deployment of the deployment member 23 can also be restricted without using a stopper. For example, if the deployment member 23 is provided on the upper surface of the exterior body 20, the deployment of the deployment member 23 can be restricted by the weight of the protective part 25. It is also possible to restrict deployment of the deployment member 23 under normal conditions by adjusting the material or thickness of the deployment part 24, and to increase the internal volume of the exterior body 20 by deforming and expanding the deployment part 24 when internal pressure increases.

[0041] <Development section status> In the above embodiment, the deployment portion 24 is normally stored in the protective portion 25 in a state where it is folded accordion-like at least once. However, this is not limited to this, and the deployment portion 24 can also be casually stored between the protective portion 25 and the exterior body 20. Furthermore, in the deployed state, a gap is formed between the exterior body 20 and the protective portion 25, and part of the deployment portion 24 is exposed (see FIG. 4). However, this is not limited to this, and the peripheral wall portion 25a can be extended upward in the pre-deployment state. As shown in FIG. 9, the peripheral wall portion 25a surrounds the exterior body 20 along the side wall of the main body portion 21 of the exterior body 20. In this way, as shown in FIG. 10, the deployment portion 24 is entirely covered by the protective portion 25 (the peripheral wall portion 25a in FIG. 10) even after deployment, making it possible to more reliably protect the deployment portion 24.

[0042] In the technology disclosed herein, each component and each process mentioned herein may be omitted or combined as appropriate, unless a particular problem arises. This specification also includes the disclosures described in the following sections.

[0043] Item 1: An electricity storage pack comprising a plurality of electricity storage devices electrically connected to each other and an exterior body that houses the plurality of electricity storage devices inside in a sealed state, wherein the exterior body comprises a deployment member that deploys when the internal pressure of the exterior body increases, thereby increasing the internal volume of the exterior body.

[0044] Item 2: The energy storage pack according to item 1, wherein the exterior body includes a main body portion that is a box-shaped rigid member that houses the energy storage device and a ventilation hole provided on the bottom surface of the main body portion, and the unfolding member includes a protective portion that is a plate-shaped rigid member that faces the bottom surface of the main body portion, and an unfolding member that is a flexible member that connects the periphery of the bottom surface of the main body portion and the protective portion so as to seal the exterior body.

[0045] Item 3: The electricity storage pack according to item 1 or 2, wherein the outer peripheral edge of the protective part is provided with a peripheral wall part that protrudes toward the bottom surface of the main body part, and the unfolding part is housed in a space surrounded by the protective part and the bottom surface of the main body part when folded.

[0046] Item 4: The storage pack of any one of items 1 to 3, wherein the exterior body includes a stopper that restricts the deployment of the deployment member, the stopper connecting the main body and the protection part, and releasing the restriction on the deployment of the deployment member when the internal pressure of the exterior body exceeds a predetermined value.

[0047] Item 5: The electricity storage pack according to any one of Items 1 to 4, further comprising a sensor that detects that the deployment member has deployed.

[0048] Item 6: A vehicle equipped with the electricity storage pack according to any one of items 1 to 5, wherein the electricity storage pack is equipped so that the deployment member deploys to the underside of the vehicle. [Explanation of symbols]

[0049] 1 Energy storage pack 10. Energy storage devices 15 Busbar 16 Electrode terminal for external connection 20 Exterior body 21 Main body of the exterior body 22 Ventilation hole 23 Deployment member 24 Development Section 25 Protection part 25a Peripheral wall part 26 Stopper 27 Fixing member 40 sensors 50 Electric Vehicles 55 Body 60 ECU 70 Display device

Claims

1. a plurality of power storage devices electrically connected to each other; an exterior body that houses the plurality of electricity storage devices in a sealed state, The outer casing is a main body portion that is a box-shaped rigid member that houses the electricity storage device; a vent provided on the bottom surface of the main body; a deployment member that deploys when the internal pressure of the exterior body increases, thereby increasing the internal volume of the exterior body; The deployment member a protective portion which is a plate-shaped rigid member facing the bottom surface of the main body portion; The electricity storage pack includes an expansion portion that is a flexible member that connects the bottom surface of the main body portion and the periphery of the protection portion so as to seal the exterior body.

2. a peripheral wall portion protruding toward a bottom surface of the main body portion is provided on an outer peripheral edge portion of the protection portion, The electricity storage pack according to claim 1, wherein the unfolding portion is housed in a space surrounded by the protection portion and a bottom surface of the main body portion in a folded state.

3. the exterior body includes a stopper that restricts deployment of the deployment member, The stopper is The main body portion and the protection portion are connected to each other, The electricity storage pack according to claim 2 , wherein the connection between the main body and the protection part is released when the internal pressure of the exterior body exceeds a predetermined value.

4. The electricity storage pack according to claim 1 , further comprising a sensor that detects that the deployment member has been deployed.

5. A vehicle equipped with the electricity storage pack according to claim 1 , wherein the electricity storage pack is equipped so that the deployment member deploys to a bottom surface of the vehicle.

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