Battery pack with gas discharge mechanism
The double-walled structure with gas discharge chambers and valves in energy storage devices addresses the risks of electric arcs and fires from malfunctioning batteries, enhancing safety and manufacturability.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- AMPERE SAS
- Filing Date
- 2021-10-11
- Publication Date
- 2026-06-26
AI Technical Summary
Conventional energy storage devices in electric and hybrid vehicles face risks of electric arcs and fires due to gas release from malfunctioning electrochemical batteries, which are complex, heavy, and bulky to manufacture.
A double-walled structure with weakened regions and gas discharge chambers, featuring openings and valves to safely vent gases away from electrical conductors, reducing the risk of arcs and fires.
The design effectively prevents electric arcs and fires by safely venting gases, maintaining structural integrity, and simplifying manufacturing.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an energy storage device or battery pack comprising an electrochemical battery and means for discharging a gas formed as a result of a malfunction of at least one electrochemical battery. The present invention also relates to a motor vehicle comprising such an energy storage device.
Background Art
[0002] Electric vehicles and hybrid vehicles comprise an energy storage device having an electrochemical battery for supplying electrical energy to an electric motor. A plurality of electrochemical batteries are usually incorporated in series or in parallel within an electrochemical module. The electrochemical modules are supported by a structure and are interconnected by electrical conductors generally referred to as "busbars". During operation, a significant potential difference may occur between different electrical conductors. Therefore, the electrical conductors are sufficiently spaced apart to prevent the formation of an electric arc.
[0003] Furthermore, electrochemical batteries are prone to problems such as thermal runaway. In that case, gas carrying metal particles may be released from the module containing the defective electrochemical battery. The presence of these gases between two electrical conductors having a large potential difference may cause an electric arc. In that case, such an electric arc may cause a hole in the structure of the energy storage device, such as the cover of the energy storage device. In that case, these holes may facilitate the entry of oxygen from the outside. And the high temperature inside the energy storage device, combined with these electric arcs and oxygen supply, may lead to a fire.
[0004] An energy storage device with a special internal conduit designed to move gas to the outside is known from document EP2654100. Such a storage device comprises a large number of elements assembled together. The above storage device is complex, heavy and bulky to manufacture.
Summary of the Invention
[0005] Presentation of the invention The object of the present invention is to overcome the aforementioned drawbacks and provide an energy storage device that improves upon conventional energy storage devices.
[0006] More specifically, one objective of the present invention is an energy storage device that is easy to manufacture and reduces all the risks associated with the formation of electric arcs due to malfunctions in electrochemical batteries.
[0007] The present invention relates to an energy storage device comprising a set of electrochemical modules and a casing housing the modules, wherein the casing comprises a double-wall structure, and each module comprises an electrochemical battery and an outer casing housing the electrochemical battery, the outer casing being provided with at least one weakening region to allow gas trapped inside the module to escape, and the structure comprising an inner wall, an outer wall, and at least one chamber formed between the inner wall and the outer wall, wherein the inner wall is provided with a set of openings positioned opposite at least one weakening region of each module, and the outer wall is provided with at least one discharge opening.
[0008] The above structure may be an extruded structure, in particular an extruded aluminum structure.
[0009] At least one weakened region formed in the outer sheath of each module may be an opening, particularly a circular opening.
[0010] The surface area of each opening in the inner wall of the above structure can be reliably made larger than the surface area of the opposing opening in the outer covering.
[0011] At least one weakening region may be located along a first side of each module, and the energy storage device may include electrical conductors that connect the modules together as a whole, the electrical conductors being located along a second side of each module substantially opposite to the first side, and the electrical conductors being located in particular substantially near the center of the energy storage device.
[0012] The above set of electrochemical modules consists of two parallel rows of electrochemical modules, and the energy storage device may include an electrical conductor positioned substantially in the boundary region between the two parallel rows.
[0013] The distance between each weakened area and the opening in the opposing inner wall may be 50 mm or less.
[0014] The above-mentioned at least one chamber can, at least locally, form a gas discharge chamber to at least one discharge opening.
[0015] The energy storage device may comprise at least two separate chambers formed between the inner and outer walls of the structure, the at least two chambers forming at least locally two separate gas discharge chambers to at least two separate discharge openings.
[0016] The energy storage device may include at least one valve designed to open gradually when the pressure in the at least one chamber becomes excessive, the at least one valve being located at at least one discharge opening.
[0017] The energy storage device may include a transverse member that separates adjacent electrochemical modules, and this transverse member is fixed to the above structure.
[0018] The present invention further relates to an automatic vehicle equipped with the energy storage device defined above.
[0019] These objects, features, and advantages of the present invention are described in detail in the following description relating to specific embodiments shown as non-limiting examples with reference to the following accompanying drawings. [Brief explanation of the drawing]
[0020] [Figure 1] This is a schematic diagram of an automated vehicle equipped with an energy storage device according to one embodiment of the present invention. [Figure 2] It is a perspective view of a double-walled structure of an energy storage device. [Figure 3] It is a perspective view of an electrochemical module of an energy storage device. [Figure 4] It is a cross-sectional view of the structure of FIG. 2. [Figure 5] It is a cross-sectional view of a valve of an energy storage device.
Mode for Carrying Out the Invention
[0021] FIG. 1 is a schematic view of a motor vehicle 1 according to an embodiment of the present invention. The vehicle 1 may be, for example, an electric vehicle or a hybrid vehicle. The vehicle 1 includes an energy storage device 2 capable of storing energy in an electrochemical form to supply electricity to an electric motor of the vehicle.
[0022] The energy storage device 2, which can also be referred to as a "battery pack" or, for convenience, "device 2", includes a set of electrochemical modules 3 and a casing for housing the modules 3. The casing forms a closed outer cover surrounding all the modules 3. Each module 3 includes an electrochemical battery or accumulator and an outer cover surrounding these batteries. The electrochemical battery can be, for example, a lithium-ion battery or any other type of battery capable of storing energy in an electrochemical form. <![CDATA[ ]]><![CDATA[
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[0024] The casing containing module 3 comprises a double-walled structure 4. Structure 4 extends along the sides of the entire module 3 assembly. The structure may be polygonal, having an overall rectangular or trapezoidal shape. The primary function of structure 4 may be to support all modules. Therefore, the structure is sufficiently robust and solid to bear the weight of the modules. Furthermore, structure 4 forms lateral protection for each module.
[0025] Referring to Figure 2, the casing further comprises a bottom cover 5 fixed to the structure 4 and a top cover (not shown). The bottom cover 5 extends substantially horizontally beneath the vehicle and can protect module 3 from external damage. Device 2 can be fixed to the lower part of the vehicle body via the casing, and more specifically via the structure 4 of the casing.
[0026] The apparatus 2 further includes a transverse member 6 that separates adjacent electrochemical modules. The transverse member 6 is fixed to the structure 4 and helps to hold each module. In other words, the transverse member 6 forms a compartment in which the modules 3 are placed. The transverse member 6 can extend parallel to each other between the two sides of the structure 4. The transverse member can extend parallel to the transverse axis of the vehicle.
[0027] Modules 3 are electrically connected to each other by electrical conductors 7, particularly busbars. The electrical conductors 7 may be, for example, metal plates or rods, and can carry a large amount of current. The metal conductors electrically connect two adjacent modules. The metal conductors are positioned substantially near the center of the storage device, i.e., substantially along the center line X that divides the device 2 into two equal halves. In other words, the metal conductors are positioned substantially within the boundary region Zx formed between two parallel columns of modules. The center line X may be substantially parallel to the longitudinal axis of the vehicle.
[0028] Figure 3 shows an electrochemical module 3 according to one embodiment of the present invention. The electrochemical module comprises an outer casing 31 having an overall parallelepiped shape that covers the electrochemical cell. Module 3 may have a size of, for example, approximately 200 mm × 200 mm × 400 mm. The outer casing 31 can form a protective seal for the electrochemical cell of module 3. The outer casing 31 may be, for example, a casing. The outer casing has a first side surface 32 facing the structure 4. Module 3 may be equipped with fastening means 33 in the form of vertical openings made to cooperate with screws. Thereafter, module 3 can be firmly connected to a bottom cover 5, which is supported by the structure 4 or any other structural element fixed to the structure 4.
[0029] The casing 31 further comprises two weakening regions 34 located on the first side 32. Alternatively, the module may have a different number of weakening regions, such as one, three, four, or five, or even more. These weakening regions can be located on different sides of the module 3. The weakening regions 34 allow gas trapped inside the electrochemical module to escape. In other words, when one or more of the electrochemical cells housed in the module 3 release gas as a result of a malfunction, the gas can escape from the casing 31 through the weakening regions 34 of the casing.
[0030] According to one embodiment of the present invention, these weakened regions 34 may be simple openings in the sheath, such as circular openings. In this case, the sheath 31 is not sealed, and the opening is simply an opening in the sheath. In another modified embodiment, the weakened regions may be areas of the sheath that are more fragile and more prone to rupture as a result of increased pressure inside the sheath. For example, the weakened regions can be created by locally thinning the sheath 31, or by pre-cutting openings into only a portion of the thickness of the sheath. In this case, the sheath can be sealed until the weakened region 34 ruptures.
[0031] Furthermore, the electrical conductor 7 connected to module 3 can preferably be positioned along the second side 35 of the sheath 31, opposite to the first side 32. This allows the electrical conductor 7 to be kept away from the weakened area along the maximum length of module 3.
[0032] An exemplary embodiment of structure 4 is clearly shown in Figure 4. Structure 4 is a double-wall structure. The structure comprises an inner wall 41 facing each module 3, an outer wall 42 facing outward from the device 2, and at least one chamber formed between the inner wall 41 and the outer wall 42. More specifically, according to the illustrated embodiment, structure 4 comprises three chambers 43A, 43B, and 43C arranged in a vertically overlapping configuration. The inner wall 41 is connected to the outer wall by four connecting walls 44. Alternatively, there may be any number of chambers, such as one or two. Each chamber is a closed space and can be independent of one another.
[0033] The structure 4 can be formed by assembling divided sections of various shapes. These divided sections can be advantageously obtained by material extrusion, particularly using aluminum. The inner wall 41 and outer wall 42 may extend substantially parallel and perpendicular to each other. The connecting wall 44 may extend substantially horizontally. Thus, as shown in Figure 4, the cross-section of the structure 4 may have an overall rectangular shape. Alternatively, the shape of this cross-section may differ, for example, a square, a triangle, or a trapezoid. Brackets 8 may be attached to the outer wall 42 to fix the bottom surface 5.
[0034] The inner wall 41 of the structure 4 is provided with a pair of openings 45 (circumstantially shown in Figures 1 and 2) positioned opposite the weakened regions 34 of each module. "Opposite" means that the openings are positioned in close proximity to the weakened regions 34 of each module, without any intervening elements. Advantageously, the weakened regions 34 are less than 50 mm, particularly less than 40 mm, preferably less than 30 mm, and even less than about 20 mm, from the openings 45. However, the distance between the openings 45 and their corresponding weakened regions 34 may be necessary, for example, to allow for easy assembly of modules within the structure and to accommodate dimensional changes due to manufacturing tolerances and / or thermal expansion.
[0035] In this way, the opening 45 allows the space housing the module 3 to communicate with at least one of the chambers 43A, 43B, and 43C. The outer wall 42 is provided with at least one discharge opening 46. In this case, the two discharge openings 46 are located on either side of the centerline X. The discharge openings 46 are not located opposite the opening 45 formed in the inner wall. Advantageously, at least one of the chambers 43A, 43B, and 43C forms a gas discharge chamber 47, at least locally, that extends from the opening 45 to the discharge opening 46. This discharge chamber is not an element attached to the device 2, but rather is directly built into the structure 4 supporting the module 3.
[0036] According to the first modified embodiment, all openings 45 can communicate with the same chamber 43A, 43B, or 43C. In another modified embodiment, individual openings 45 can communicate with separate chambers of the structure. In either case, exhaust openings 46 are naturally provided in each chamber into which gas is likely to enter. This allows for the separate handling of different gas flows and, in particular, reduces the risk that gas entering a chamber through the first opening 45 may subsequently enter the space housing the module through the second opening 45.
[0037] Advantageously, the discharge opening 46 can be separated from the opening 45 formed in the inner wall by a distance that is certainly greater than the distance that separates the weakened region 34 from the opening 45. For example, this distance may be at least 60 mm, preferably at least 70 mm, and even more preferably at least 80 mm.
[0038] The apparatus 2 further comprises valves 9 positioned at each of the discharge openings 46, which are designed to open gradually when the pressure in the communicating chamber becomes excessive. These valves may include elastic elements such as springs, although exemplary embodiments are shown in Figure 5. The valves can be set to open gradually when the gas pressure in the corresponding chamber reaches or exceeds a given threshold. When these valves are closed, the casing can be sealed, that is, the gas cannot escape from the casing until the pressure inside the casing reaches the valve opening pressure.
[0039] Advantageously, the surface area of the opening constituting the weakened region 34 is certainly smaller than the surface area of the opening 45 and certainly smaller than the flow path area of the valve 9. The flow path area of the valve 9 may be intermediate between the surface area of the weakened region 34 and the surface area of the opening 45. For example, the opening forming the weakened region 34 may be 300 mm 2 ~400mm 2 It may have a surface area of (including the values at both ends). The opening 45 is 500 mm 2 ~700mm 2 It may have a surface area of (including the values at both ends). The flow path opening of valve 9 is 400 mm 2 ~500mm 2 (This can include the numbers at both ends.)
[0040] To manufacture the apparatus 2 mentioned above, the structure 4 can be manufactured by assembling extruded aluminum segmented parts into which openings 45 and 46 are fabricated. These openings can be made by simply drilling. Advantageously, the dimensions presented for the openings 45, 46 are small enough to have little effect on the rigidity of the structure 4, while being large enough to efficiently vent the gas. The valve 9 can be easily fitted into the corresponding opening 46. Module 3 can be positioned between the transverse members 6 inside the structure 4. Module 3 is then fixed directly or indirectly to the structure 4 such that the weakening region 34 is positioned opposite the opening 45.
[0041] When the vehicle is in motion, current can flow through the electrical conductor 7. A large potential difference can occur between adjacent electrical conductors. For example, this potential difference (indicated by arrow F1 in Figure 1) can reach a height of about 400V. However, under normal operating conditions, the electrical conductors 7 are spaced far enough apart to prevent the formation of an electric arc.
[0042] If the electrochemical module 3 or the electrochemical cell housed within the module malfunctions, gas (indicated by reference numeral 10 in Figure 1) may be generated within the module. The gas increases the pressure inside the module's casing 31 and eventually leaks out of the module 3 through one of the weakening regions 34. Since this weakening region is located close to the opening 35, the gas naturally flows into one of the chambers 43A, 43B, or 43C. Advantageously, since the surface area of the opening 45 is certainly larger than the surface area of the weakening region, all or almost all of the gas flow can flow from the cell 3 into the chamber formed in the structure 4. The gas pressure inside the chamber rises to a height sufficient to open the valve 9. The gas then escapes from the structure 4 through the valve 9. At this point, the gas flow (indicated by arrow F2 in Figure 1) certainly flows from the inside to the outside of the device. This gas flow creates an attractive effect that draws the gas into the opening 45. Therefore, the gas is not dispersed around the modules inside the casing, and in particular, does not come close to the electrical conductors 7. This reduces the risk of electrical arcing if gas leakage occurs in one of the modules. Placing the electrical conductors 7 on the module side opposite the weakened region 34 further reduces this risk. Furthermore, it prevents hot gas leaking from one module from heating an adjacent electrochemical module, which would lead to thermal runaway.
[0043] Advantageously, the presence of the valve prevents new air from entering device 2 in the opposite direction to the gas. This prevents oxygen, which could cause a fire, from entering the device.
[0044] Advantageously, the walls of structure 4 have high thermal inertia, allowing the gas to cool as it is discharged. This reduces the risk of spontaneous combustion of the gas at the valve outlet.
Claims
1. The system comprises a set of electrochemical modules (3) and a casing that houses the modules, the casing comprising a double-walled structure (4), each module (3) comprising a plurality of electrochemical cells and an outer cover (31) that houses the plurality of electrochemical cells, the outer cover being provided with at least one weakening region (34) that allows gas trapped inside the module to escape, the structure (4) comprising an inner wall (41), an outer wall (42), and at least one chamber (43A, 43B, 43C) formed between the inner wall and the outer wall, the inner wall being provided with a set of openings (45) positioned opposite the at least one weakening region of each module, and the outer wall being provided with at least one discharge opening (46). An energy storage device (2) characterized by the following.
2. The energy storage device (2) according to claim 1, characterized in that the structure (4) is an extruded structure, in particular an extruded aluminum structure.
3. The energy storage device according to claim 1 or 2, characterized in that the at least one weakened region (34) formed in the outer casing (31) of each module (3) is an opening, particularly a circular opening.
4. The energy storage device (2) according to claim 3, characterized in that the surface area of each opening (45) of the inner wall (41) of the structure (4) is strictly larger than the surface area of the opposing openings of the outer covering (31).
5. The energy storage device (2) according to any one of claims 1 to 4, characterized in that the at least one weakened region (34) is arranged along a first side surface (32) of each module, and the energy storage device comprises an electrical conductor (7) that integrally connects the modules together, wherein the electrical conductor is arranged along a second side surface (35) of each module substantially opposite to the first side surface, and the electrical conductor is arranged in particular toward substantially the center of the energy storage device.
6. The energy storage device (2) according to any one of claims 1 to 5, characterized in that the set of electrochemical modules (3) comprises two parallel rows of electrochemical modules, and the energy storage device comprises an electrical conductor (7) substantially located in the boundary region (Zx) between the two parallel rows.
7. The energy storage device (2) according to any one of claims 1 to 6, characterized in that the distance between each weakened region (34) and the opening (45) of the opposing inner wall (41) is 50 mm or less.
8. The energy storage device (2) according to any one of claims 1 to 7, characterized in that the at least one chamber (43A, 43B, 43C) forms at least locally a gas discharge chamber (47) to the at least one discharge opening.
9. The energy storage device (2) according to claim 8, comprising at least two separate chambers (43A, 43B, 43C) defined between the inner wall (41) and the outer wall (42) of the structure (4), wherein the at least two chambers form at least locally two separate gas discharge chambers (47) to at least two separate discharge openings (46).
10. An energy storage device (2) according to any one of claims 1 to 9, comprising at least one valve (9) designed to open gradually when the pressure in at least one chamber (43A, 43B, 43C) becomes excessive, wherein the at least one valve is located in the at least one discharge opening (46).
11. An energy storage device (2) according to any one of claims 1 to 10, characterized in that it comprises a transverse member (6) that separates adjacent electrochemical modules (3), and the transverse member is fixed to the structure (4).
12. An automatic vehicle (1) characterized by comprising an energy storage device (2) according to any one of claims 1 to 11.