CELL COOLING PLATE FOR AN ELECTRICAL STORAGE DEVICE

Abstract

One aspect of the invention relates to a cooling plate 5 for electrochemical cells 3 of an electrical storage device 1, the cooling plate 5 being arranged to be sandwiched between two electrochemical cells 3 of the electrical storage device 1, the cooling plate 5 comprising: a cooling circuit 6 of the oscillating heat pipe type constructed and arranged to contain a two-phase cooling fluid, and a first exhaust device 8 constructed and arranged to allow evaporation of a portion of the two-phase cooling fluid when it reaches a first predetermined threshold temperature or a first predetermined threshold pressure. Figure 2

Description

Title of the invention: COOLING PLATE FOR CELLS OF AN ELECTRICAL STORAGE DEVICE

[0001] The present invention relates to the cooling of cells in an electrical storage device. More particularly, one aspect of the invention relates to a cell cooling plate for an electrical storage device. Another aspect of the invention relates to an electrical storage device comprising such a cell cooling plate.

[0002] Vehicles, whether fully electric or combining the use of a combustion engine and an electric motor, are equipped with electrical storage devices, generally comprising several electrical modules. These electrical modules comprise a plurality of interconnected electrical cells.

[0003] These electrical modules do not tolerate operation well outside a specific temperature range. Therefore, they must be maintained within a given temperature range. For example, lithium-ion batteries operate optimally between 0°C and 50°C. Effective thermal management is necessary to ensure that the cells remain within this temperature range regardless of atmospheric and operating conditions.

[0004] The most critical use case, the one that determines the cooling capacity, is encountered during thermal runaway events or ultra-fast charging. This rapid charging causes the electrical storage device to heat up, requiring greater cooling capacity.

[0005] Among the proposed solutions to slow down and protect against thermal runaway, interface insulating materials to isolate cells against the propagation of this phenomenon may be provided.

[0006] A cell separator including a pipe for the passage of a coolant is also known from document JP-B2-5994345. This pipe has a section whose thickness is intentionally thin so that it can rupture upon an increase in the pressure of the coolant.

[0007] When the pipe breaks, the module must be replaced. This solution is therefore particularly expensive.

[0008] The object of the invention is to overcome the disadvantages of the prior art by proposing a low-cost cooling plate for cells of an electrical storage device.

[0009] In this context, the invention thus relates, in its broadest sense, to a cooling plate for electrochemical cells of a device electrical storage, the cooling plate being arranged to be sandwiched between two electrochemical cells of the electrical storage device, the cooling plate including a cooling circuit for the two electrochemical cells.

[0010] The cooling plate according to this aspect of the invention is remarkable in that the cooling circuit is an oscillating heat pipe constructed and arranged to contain a two-phase cooling fluid and in that the cooling plate includes a first exhaust device constructed and arranged to allow evaporation of a portion of the two-phase cooling fluid when the two-phase cooling fluid reaches a first predetermined threshold temperature or a first predetermined threshold pressure.

[0011] Thus, for example, as soon as the two-phase cooling fluid reaches a first predetermined threshold temperature, for example of 130°C, the first exhaust device releases a portion of the two-phase cooling fluid in vapor phase so as to cool the cell onto which the two-phase cooling fluid in vapor phase is projected.

[0012] The escape device can be formed by a thermal fuse using a wax that reacts according to temperature to allow the coolant to pass through. If this thermal fuse is used, it is easy and inexpensive to replace.

[0013] In a different embodiment, the exhaust device may consist of a pressure relief valve that reacts to pressure to allow the cooling fluid to pass through. Such a pressure relief valve may be used many times or require replacement.

[0014] In addition, the use of an oscillating heat pipe as a cooling circuit makes it possible to avoid using a pump for the circulation of the cooling fluid.

[0015] Indeed, the oscillating heat pipe contains a two-phase heat transfer fluid that naturally forms a succession of vapor bubbles and liquid plugs. The temperature differences present in the oscillating heat pipe generate pressure fluctuations that act as a pumping system, allowing the coolant to circulate.

[0016] In addition to the characteristics just mentioned in the preceding paragraph, the device according to this aspect of the invention may have one or more complementary characteristics from among the following, considered individually or according to all technically possible combinations.

[0017] According to a non-limiting aspect of the invention, the cooling plate includes a first filling port for the cooling circuit, the first filling port being equipped with the first exhaust device.

[0018] According to a non-limiting aspect of the invention, the cooling plate includes a reservoir of an inert gas and a second exhaust device constructed and arranged to allow evaporation of a portion of the inert gas when the inert gas reaches a second predetermined threshold temperature or a second predetermined threshold pressure.

[0019] According to a non-limiting aspect of the invention, the cooling plate includes a second port for filling the reservoir with an inert gas, the second filling port being equipped with the second exhaust device.

[0020] According to a non-limiting aspect of the invention, the second escape device is formed by a thermal fuse or a pressure relief valve.

[0021] According to a non-limiting aspect of the invention, the first escape device is formed by a thermal fuse or a pressure relief valve.

[0022] According to a non-limiting aspect of the invention, the cooling plate has a thickness of between 1.8 mm and 3.2 mm.

[0023] Another aspect of the invention relates to an electrical storage device comprising two adjacent electrochemical cells, the electrical storage device being notable in that it comprises an electrochemical cell cooling plate according to any one of the aforementioned aspects of the invention, the cooling plate being sandwiched between the two electrochemical cells.

[0024] According to a non-limiting aspect of the invention, the first escape device opens at a peripheral edge of the two electrochemical cells.

[0025] According to a non-limiting aspect of the invention, the electrochemical cell cooling plate is placed on a cooling support for the cooling plate.

[0026] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures.

[0027] [Fig-1] illustrates, schematically, an electrical storage device according to a non-limiting aspect of the invention.

[0028] [Fig.2] shows, schematically, a cooling plate according to a non-limiting aspect of the invention.

[0029] [Fig.3] illustrates, schematically, an example of manufacturing a cooling plate as illustrated in [Fig.2].

[0030] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0031] Fig. 1 schematically illustrates an electrical storage device 1. This electrical storage device 1 can be fitted to a motor vehicle comprising an electric motor for its traction.

[0032] In the remainder of this description, the electrical storage device 1 will be understood to mean an assembly comprising at least one battery module 2 (two in the illustrated example), each battery module 2 containing electrochemical cells 3, eight in the illustrated example.

[0033] The modules 2 are grouped in a container or housing 4.

[0034] Furthermore, the term electrochemical cell 3 shall be understood to mean an electrical energy storage cell. This electrochemical cell 3 is arranged to generate current by chemical reaction, for example of the lithium-ion (or Li-ion), Ni-Mh, Ni-Cd or lead type.

[0035] The electrical storage device 1 comprises several cooling plates 5. The cooling plates 5 have the function of preventing thermal runaway of the electrical storage device 1. Each cooling plate 5 is sandwiched between two adjacent electrochemical cells 3, in other words the electrochemical cells 3 are in thermal contact with a cooling plate 5.

[0036] As illustrated in [Fig. 2], each cooling plate 5 comprises a cooling circuit 6 formed by an oscillating heat pipe constructed and arranged to contain a two-phase cooling fluid. The cooling circuit 6 is characterized by its capillary-sized coil. This coil is partially filled with a two-phase cooling fluid, which is distributed into vapor pockets and liquid plugs. The pressure difference between two vapor pockets provides the driving force for the fluid's movement.

[0037] The cooling plate 5 further includes, at its upper part, a first filling port 7 for the cooling circuit 6.

[0038] In addition, the cooling plate 5 has, at its upper part, a first exhaust device 8 constructed and arranged to allow evaporation of a part of the two-phase cooling fluid when the two-phase cooling fluid reaches a first predetermined threshold temperature.

[0039] When the cooling plate 5 is positioned between two electrochemical cells 3, the first exhaust device 8 opens at a peripheral edge of the two electrochemical cells 3, formed in this example by the upper edge of the two electrochemical cells 3.

[0040] Such a first escape device 8 can be formed by a thermal fuse comprising a wax which reacts according to the temperature to allow the two-phase cooling fluid to pass through.

[0041] In a non-limiting example embodiment, the first temperature threshold is between 110°C and 150°C, typically 130°C.

[0042] During its evaporation, the two-phase cooling fluid is vaporized on the adjacent electrochemical cell 3 so as to promote its cooling.

[0043] In this non-limiting embodiment, the first escapement device 8 is integrated into the first filling port 7. It is understood that, in a different embodiment, the first filling port 7 and the first escapement device 8 may be separated from each other.

[0044] In this embodiment, the cooling plate 5 also includes a reservoir of an inert gas 9. By way of non-limitation, the inert gas contained may be carbon dioxide or nitrogen.

[0045] The cooling plate 5 further includes, at its upper part, a second filling port 10 for the reserve of an inert gas 9.

[0046] In addition, the cooling plate 5 has, at its upper part, a second exhaust device 11 constructed and arranged to allow evaporation of part of the inert gas when the inert gas reaches a second predetermined threshold temperature.

[0047] When the cooling plate 5 is positioned between two electrochemical cells 3, the second exhaust device 11 opens at a peripheral edge of the two electrochemical cells 3, formed in this example by the upper edge of the two electrochemical cells 3.

[0048] Such a second escape device 11 can be formed by a thermal fuse comprising a wax which reacts according to the temperature to allow the two-phase cooling fluid to pass through.

[0049] In a non-limiting example embodiment, the second temperature threshold is between 110°C and 150°C, typically 130°C.

[0050] During its evaporation, the inert gas is vaporized on the adjacent electrochemical cell 3 so as to prevent a thermal runaway of this electrochemical cell 3.

[0051] In this non-limiting embodiment, the second escapement device 11 is integrated into the second filling port 10. It is understood that, in a different embodiment, the second filling port 10 and the second escapement device 11 may be separated from each other.

[0052] It should also be noted that the cooling plates 5 are placed on a cooling support 12. In a non-limiting example of embodiment, this cooling support 12 may be formed by the bottom of the electrical storage device 1 and be traversed by a conduit 13 containing a cooling fluid whose circulation is achieved by means of a pump 14 and / or include cooling fins.

[0053] Furthermore, in order to compensate for any possible swelling of the electrochemical cells 3 occurring during their charging and discharging, each cooling plate 5 has a thickness between 1.8 mm and 3.2 mm, typically 2 mm.

[0054] The cooling plates 5 also ensure a compressive prestress of all the electrochemical cells 3.

[0055] The cooling plates 5 can be made of a metallic or plastic material.

[0056] In the case of a metallic material, the cooling circuit 6 can be machined in a first wall 15 and a second wall 16 can be welded to said first wall 15. In this case, the second wall 16 forms part of the wall of the cooling circuit 6.

[0057] The various aspects of the aforementioned invention offer numerous advantages.

[0058] Indeed, in the cooling circuit 6, a first filling port 7 is closed by a first thermal fuse 8 which allows the two-phase cooling fluid to escape during a thermal runaway of the electrical storage device 1. This particular escape makes it possible to secure the electrical storage device 1 by lowering the temperature of the electrochemical cells.

[0059] In addition, each cooling plate 5 has a reservoir of an inert gas 9 which is equipped with a second filling port 10 closed by a second thermal fuse 11. This second thermal fuse 11 allows the inert gas to escape during a thermal runaway of the electrical storage device 1 to prevent its propagation.

[0060] It should be noted that the first exhaust device 8 and the second exhaust device 11 are formed by a thermal fuse. In a different embodiment, the first exhaust device 8 and the second exhaust device 11 are formed by a pressure relief valve that reacts to an overpressure to allow the two-phase cooling fluid to pass through.

[0061] In yet another embodiment, the first exhaust device 8 is formed by a thermal fuse and the second exhaust device 11 is formed by a pressure relief valve or vice versa.

Claims

Demands

1. Cooling plate (5) for electrochemical cells (3) of an electrical storage device (1), said cooling plate (5) being arranged to be sandwiched between two electrochemical cells (3) of said electrical storage device (1), said cooling plate (5) comprising a cooling circuit (6) for said two electrochemical cells (3), said cooling plate (5) being characterized in that said cooling circuit (6) is an oscillating heat pipe constructed and arranged to contain a two-phase cooling fluid, said cooling plate (5) comprising a first exhaust device (8) constructed and arranged to permit evaporation of a portion of said two-phase cooling fluid when said two-phase cooling fluid reaches a first predetermined threshold temperature or a first predetermined threshold pressure,as well as a reservoir of an inert gas (9) and a second exhaust device (11) constructed and arranged to permit evaporation of a portion of said inert gas when said inert gas reaches a second predetermined threshold temperature or a second predetermined threshold pressure.

2. Cooling plate (5) according to claim 1, characterized in that it comprises a first filling port (7) of said cooling circuit (6), said first filling port (7) being provided with the first exhaust device (8).

3. Cooling plate (5) according to claim 1 or 2, characterized in that it comprises a second filling port (10) for the reserve of an inert gas (9), said second filling port (10) being provided with the second exhaust device (H).

4. Cooling plate (5) according to any one of the preceding claims, characterized in that the second exhaust device (11) is formed by a thermal fuse or a pressure relief valve.

5. Cooling plate (5) according to any one of the preceding claims, characterized in that the first exhaust device (8) is formed by a thermal fuse or a pressure relief valve.

6. Cooling plate (5) according to any one of the preceding claims, characterized in that it has a thickness between 1.8 mm and 3.2 mm.

7. Electrical storage device (1) comprising two adjacent electrochemical cells (3), said electrical storage device (1) being characterized in that it comprises a cooling plate (5) for electrochemical cells (3) according to any one of the preceding claims, said cooling plate (5) being sandwiched between said two electrochemical cells (3).

8. Electrical storage device (1) according to the preceding claim, characterized in that the first escape device (8) opens at a peripheral edge of the two electrochemical cells (3).

9. Electrical storage device (1) according to any one of claims 7 or 8, characterized in that the cooling plate (5) of electrochemical cells is placed on a cooling support (12) of said cooling plate (5).

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