Battery comprising at least one stack of cells and associated elastic device for compensating cap

Abstract

The invention relates to a battery (1) for storing electrical energy, comprising: at least one stack (7) of cells (6); and a case comprising a base (3) to which the cell stack (7) of the battery (1) is attached. The battery (1) comprises: at least two compressed plates (8) arranged on both sides of the stack; means (10) for attaching the compression plates (8) to the base (3); at least one tie rod (12) capable of pressing the compression plates (8) against the cells (6) of the stack (7); and at least one elastic device (15) for compensating for the gap of the stack in the direction of the dimensional change of the stack, the device comprising at least one flat wire wave spring.

Description

Technical Field

[0001] This invention relates to the storage of electrical energy, particularly in the field of aviation. The invention generally relates to the storage of electrical energy for applications where quality is a critical issue, such as in aviation. Background Technology

[0002] Traditionally, in the aviation industry, electrical energy storage has been carried out using low-voltage lithium-ion batteries (typically with a voltage below 120V).

[0003] The term "battery" refers to a set of individual modules, each comprising multiple power elements arranged in series and / or parallel to achieve the desired voltage and capacitance.

[0004] Modern aircraft have an ever-increasing demand for electricity, necessitating the corresponding battery configuration. In fact, climate change is a major concern for many legislative and regulatory bodies around the world. Countries have already implemented, are implementing, or will implement various measures to limit carbon emissions.

[0005] For several years, civil aviation has been committed to contributing to the fight against climate change.

[0006] Research efforts have enabled significant improvements in the environmental performance of aircraft. Therefore, the applicant continues to strive to reduce its negative climate impacts in order to minimize the environmental footprint of its activities by using appropriate methods and leveraging suitable development and manufacturing approaches, and minimizing greenhouse gas emissions as much as possible.

[0007] This ongoing research and development work involves next-generation aircraft engines, making aircraft lighter (particularly through the use of materials and lighter avionics), developing and utilizing electrical technologies to provide propulsion, and aviation biofuels.

[0008] In order to provide the necessary power in the aircraft network while minimizing the weight of electrical equipment, it is advantageous to increase the battery voltage to, for example, 800 V.

[0009] Inside a high-voltage battery, power components or battery cells are typically grouped into multiple modules, each containing a specific number of cells, including devices for mechanical attachment, electrical connection, and potential temperature regulation.

[0010] To improve the integration of batteries in terms of size and weight, multiple cells are typically stacked along the stacking axis within a battery module.

[0011] However, based on the chemical properties of the cell, it is necessary to consider the possible significant changes in cell thickness along the stack axis during charge and discharge cycles, otherwise there is a risk of damaging the cell structure, or even the structure holding the cell in place.

[0012] Traditionally, to account for the risks associated with such dimensional changes, foam layers are inserted between the cells along the stack axis. These foam layers allow for a degree of deformation. Therefore, the foam layers change with the expansion and contraction of the cells, while simultaneously providing a return pressure adapted to the cell structure.

[0013] However, the mechanical properties of foam can sometimes lead to a significant increase in pressure, requiring an increase in the number of foam layers, thus negatively impacting overall integration in terms of volume and mass. Furthermore, the mechanical properties of foam change with aging, resulting in residual deformation of the foam. Summary of the Invention

[0014] Therefore, the object of the present invention is to provide a battery for storing electrical energy, particularly for aircraft, which enhances integration in terms of volume and mass while taking into account dimensional changes in the cells during charge and discharge cycles. Specifically, a battery module structure is sought that allows for some variation in the thickness of the cells along their stacking axis without the risk of compromise or loss of the cells' mechanical integrity.

[0015] The present invention relates to a battery for storing electrical energy, the battery comprising at least one cell stack and a housing, the housing comprising a base to which the cell stack is attached.

[0016] The battery includes: at least two compression plates disposed on both sides of the stack; means for attaching the compression plates to the base; at least one pull rod capable of pressing the compression plates against the cells of the stack; and at least one elastic device for compensating for gaps in the stack in the direction of dimensional change of the stack, the device including at least one flat-wire wavespring. Such a spring improves the compactness of the elastic device.

[0017] Preferably, each elastic device includes at least one spring compressed between a pair of support members substantially perpendicular to the direction of dimensional change of the stack. Such an elastic device can absorb any dimensional change of the stack by means of changes in the length of the compressed spring.

[0018] Advantageously, each support member includes a first surface and a second surface, which are planar and opposite to each other, and the second surface is provided with a reinforcement designed to accommodate the end of at least one compressed spring. Such a reinforcement facilitates the mounting and retention of the spring on the second surface, while increasing the stiffness of the support member.

[0019] Advantageously, at least one elastic device includes at least one spring having an axial orientation oriented along the direction of dimensional change of the stack.

[0020] For example, at least one elastic device includes multiple concentric springs about the direction of dimensional change of the stack. Such a configuration helps to achieve the required stiffness of the elastic device.

[0021] Preferably, these support components are made of electrically insulating material. Such support components improve the electrical safety of the battery environment, especially in terms of leakage current.

[0022] According to one feature, adjacent support members corresponding to adjacent stacks each include a first hook and a second hook, the first hook and the second hook being opposite each other and aligned in a transverse direction perpendicular to the longitudinal axis of the adjacent stacks. These hooks have complementary U-shapes, thereby allowing the first hook of the first support member to slide through the second hook of the second support member adjacent to the first support member and allowing the pull rod to pass through these hooks without hindering the relative translation of the adjacent support members in the direction of dimensional change of the stack.

[0023] According to another feature, the number of tie rods is one more unit than the number of cell stacks. This configuration allows for a reduced number of tie rods, thereby enhancing integration in terms of mass and volume.

[0024] According to another aspect, the present invention relates to an aircraft comprising a battery as described above. Attached Figure Description

[0025] Other objects, features, and advantages of the invention will become apparent upon reading the following description, which is by way of non-limiting example only, and with reference to the accompanying drawings, in which: [ Figure 1 [Illustrated perspective view of a battery for storing electrical energy according to an embodiment of the present invention;] [ Figure 2 ]yes Figure 1 A 3D view of the battery, in which the outer casing has been removed; [ Figure 3 ]yes Figure 2 A side view of the battery; and [ Figure 4 [Illustration 1] is a perspective view of a support member according to an example of the present invention. Detailed Implementation

[0026] Figure 1 and Figure 2 An exemplary embodiment of a battery for storing electrical energy according to the present invention is shown, the battery being generally indicated by reference numeral 1.

[0027] Battery 1 includes a housing 2, which includes a base 3. Preferably, housing 2 includes an outer casing 4 that covers the base 3. Housing 2 is designed to ensure the assembly, connection, and protection of the power components of battery 1, which can be... Figure 2 As seen in, Figure 2 The inner casing is not shown.

[0028] The housing 2 is provided with means for mechanically attaching the housing to the base, which is made, for example, in the form of screws, bolts or any other suitable attachment means for the intended purpose.

[0029] In the described embodiment, battery 1 is intended to be placed on an aircraft, such as in a turbine engine. Battery 1 is used, for example, to selectively deliver electrical energy for electric propulsion purposes. However, it should be noted that the invention is also generally applicable to other fields and environments (automotive, railway, etc.) where significant management and integration issues arise.

[0030] Furthermore, the base 3 is equipped with multiple attachment elements 5, which allows the base to be mounted on an aircraft. However, it should be noted that the base 3 can alternatively be formed from a structural support element of the aircraft, which is configured to integrate the battery.

[0031] As for the outer casing 4, it covers all the components located inside the housing 2 and represents a physical barrier that separates and protects the interior of the housing 2 from the external environment of the housing.

[0032] In the presence of the housing 4, the housing 4 is specifically designed to reduce the risk of gas leakage. Preferably, a seal is thus implemented between the base 3 and the housing 4 to contain the gas.

[0033] Furthermore, in the event of thermal runaway of battery 1, housing 4 ensures the protection of housing 2 from the external environment by limiting the impact of the event on housing 2.

[0034] The power components of battery 1 include multiple cells 6. Preferably, these cells 6 are in a flexible package form, commonly referred to as a "bag". Alternatively, these cells may be prismatic or even cylindrical.

[0035] Cell 6 is grouped into at least one stack 7. In other words, the cells of the stack are arranged side by side along the longitudinal axis X of the stack. Figure 3 Preferably, the longitudinal axis X of the stack is parallel to the base 3. The longitudinal axis X is preferably parallel to the direction of dimensional change of the stack.

[0036] The battery 1 includes at least two opposing compression plates 8 disposed on both sides of the cell stack 7. The compression plates 8 are laterally positioned at the ends of at least one stack 7. Preferably, the number of compression plates is limited to two, i.e., one on each side; however, it is still possible to provide a greater number of plates 8.

[0037] The compression plate 8 has a certain rigidity, which allows it to meet the maximum allowable deformation standard along the longitudinal axis X of the stack under the maximum pressure applied by the cell 6. For example, the rigidity of the plate 8 ensures that the maximum deformation is less than 0.1 mm.

[0038] In order to reduce weight while meeting the maximum deformation standard, the compression plate 8 includes a reinforcement 8a.

[0039] Preferably, the compression plate 8 is substantially planar and extends perpendicular to the longitudinal axis X of the cell stack.

[0040] The compression plate 8 is attached to the base 3 via the attachment device 10 at its lower part 9.

[0041] In this example, multiple compression plates 8 are connected to each other via their upper parts 11 by at least one tie rod, preferably by multiple tie rods 12.

[0042] Preferably, the tie rod 12 is installed in a direction parallel to the longitudinal axis X of the stack 7 and parallel to the base 3.

[0043] Advantageously, the number of tie rods 12 is reduced compared to conventional solutions, where tie rods exist in both the lower and upper parts of the compression plate. Multiple tie rods 12 are preferably arranged only in the upper part 11 of the compression plate 8. Therefore, a single cell stack can be held by only two tie rods. Alternatively, a single tie rod 12 can be provided only in the upper part 11 of the compression plate 8 to further reduce the number of tie rods.

[0044] The result here is that the total number of levers 12 is one unit more than the number of stacked bodies 7. Figure 2 In the example shown, for three stacked bodies 7, there are four tie rods 12, meaning the number of tie rods is one more than the number of stacked bodies. This reduction in the number of tie rods allows for better integration in terms of mass and volume.

[0045] The base 3 ensures thermal management functionality and is associated with a thermal management device for this purpose. The thermal management device may specifically include at least one heat exchanger 13, which is provided with conduits in which a heat transfer fluid circulates. The heat transfer fluid is, for example, a coolant. For example, the heat exchanger 13 has a spiral shape. The base 3 is advantageously made of a thermally conductive material, particularly a metallic material.

[0046] The heat exchanger 13 is integrated into the base 3, for example, which optimizes the thermal path between the cell and the fluid by reducing the thermal resistance associated with the channels between the components. Alternatively, the heat exchanger can be mounted for heat exchange with the base 3, preferably with the outer surface of the base 3 (i.e., the surface opposite to the inner surface of the housing cell 6). Thus, the heat exchanger 13 is, for example, attached to the surface of the base 3.

[0047] The base 3 exchanges heat with the cell 6, thus allowing the cell 6 to be maintained at its optimal operating temperature.

[0048] Preferably, the battery 1 includes at least one intermediate wall 14, which is attached to the base 3, oriented parallel to the cell 6, and disposed inside each stack 7. Figure 1 A single intermediate wall 14 is shown disposed in the central region of the base 3 (roughly corresponding to the middle of the base 3). Alternatively, multiple intermediate walls may still be provided, which are disposed at regular intervals in each stack body. Preferably, the intermediate wall 14 extends over most of the width of the base 3.

[0049] The presence of the intermediate wall 14 helps to strengthen the stack 7 and has the effect of limiting deformation in a direction orthogonal to the base 3. The presence of the intermediate wall 14 contributes to the good vibration resistance of the battery 1. However, the intermediate wall 14 may not be provided.

[0050] Battery 1 includes at least one flexible device 15 ( Figure 3 The at least one elastic device is used to compensate for gaps in the stack 7 in the direction of dimensional change of the stack 7 during charging or discharging of the cells 6 of the stack 7. Preferably, at least one elastic device 15 is associated with each stack 7 to ensure elastic support for each stack 7 in the direction of dimensional change of the stack 7. Typically, the direction of dimensional change of the stack 7 is in the thickness direction of the plurality of cells 6 forming the stack 7 (i.e., parallel to the longitudinal axis X).

[0051] Therefore, each elastic device 15 elastically supports its associated stack 7. In other words, each elastic device 15 elastically deforms and provides an elastic compressive force to the associated stack, which is preferably applied over the entire range of dimensional changes of the stack. Within the elastic range, no residual deformation of the elastic device is formed.

[0052] From one drawing to another, the same reference numerals correspond to the same elements.

[0053] exist Figure 3In the example shown, battery 1 includes two resilient support devices 15 disposed within the stack 7. The position and number of devices 15 can still be adjusted without departing from the scope of the invention. For example, when battery 1 does not include the intermediate wall 14, the devices 15 can be disposed in the central region of base 3 (approximately corresponding to the middle of base 3). It should be noted that the devices 15 being located in the middle of a segment of the stack 7 (with the ends of that segment remaining fixed) has the advantage of minimizing the maximum movement of the internal components of battery 1 caused by the charging and discharging of the cells 6. The maximum value of the caused movement can also be reduced by distributing several devices 15 associated with any segment of the stack 7 (with the ends of that segment remaining fixed). In embodiments not shown, foam layers can also be added between the individual cells 6 of the stack 7. These foam layers ensure thermal insulation and have the resilience to compensate for dimensional changes in the cells 6 during their operation, while restoring pressure adapted to the permissible limits of the cells 6.

[0054] The elastic device 15 includes at least one compressed spring 16 located between a pair of support members 17, which are substantially perpendicular to the direction of dimensional change of the stack. The support members 17 are rigid enough to distribute the compressive force of the spring evenly across the cells of the stack. The support members can be reinforced to increase their stiffness while optimizing their mass.

[0055] like Figure 4 As shown, each support member 17 includes a first surface 18 and a second surface 19, which are planar and opposite to each other. The second surface 19 is provided with a reinforcement 20, which is designed to accommodate the end of at least one compressed spring 16. Preferably, the support member 17 is made of an electrically insulating material.

[0056] Preferably, the elastic device 15 includes at least one flat wire wave spring to optimize the size of the device 15. Alternatively, other spring systems can be used. For example, a stack of washers, such as a Belleville washer stack, can be used. Of course, a round-wire coil spring can still be used alone.

[0057] Preferably, the spring 16 has an axial orientation oriented along the direction of dimensional change of the associated stack to optimize the support force.

[0058] In an example not shown, multiple concentric springs 16, such as two concentric springs, can be used within the same elastic device 15 around the direction of dimensional change of the cell stack to obtain the desired stiffness.

[0059] refer to Figure 3Each cell 6 includes a first outer surface S1 and a second outer surface S2 opposite to the first surface.

[0060] exist Figure 3 In the illustrated embodiment, the first outer surface S1 of each cell 6 is in contact with the heat dissipation device 23. Alternatively, it may still be possible that only some cells 6 of a given stack are in contact with the heat dissipation device, or that cells 6 are not in contact with any dissipation device.

[0061] Preferably, the heat dissipation device 23 includes at least one graphite layer and at least one adhesive layer. The graphite layer of the heat dissipation device 23 is positioned to contact the outer surface S1 of the associated battery cell 6 in order to maximize the heat transfer capability between the dissipation device and the associated battery cell.

[0062] In a particular embodiment, the heat emission device 23 includes a metal layer (e.g., made of aluminum or copper) combined with an adhesive layer and a graphite layer.

[0063] Each heat dissipation device 23 preferably includes a main portion 23a and an end portion 23b. The main portion 23a is oriented in a direction perpendicular to the longitudinal axis X of the stack, which is orthogonal to the surfaces S1 and S2 of the cell 6. In other words, the main portion 23a of the heat dissipation device 23 is parallel to the surfaces S1 and S2. The main portion 23a contacts the surface S1 of the associated cell 6, and the end portion 23b is folded under the associated cell 6 to form the surface 23c of the dissipation device 23 that contacts the base 3.

[0064] The attachment device 10 of the compression plate 8 preferably includes a first attachment element 24 and a second attachment element 25. The first attachment element 24 is attached to the base 3. The first attachment element is designed to pass through a hole provided in the base plate 26 of each compression plate 8 and cooperate with the second attachment element 25 to attach the compression plate 8 to the base 3. The first attachment element 24 may in particular be a stud, screw, or bolt. The second attachment element 25 may be a nut.

Claims

1. A battery (1) for storing electrical energy, the battery comprising at least one stack (7) of cells (6) and a housing (2), the housing comprising a base (3) to which the stack (7) of the battery (1) is attached, Its features are, The battery (1) includes: at least two compression plates (8) disposed on both sides of the stack (7); means (10) for attaching the compression plates (8) to the base (3); at least one pull rod (12) capable of pressing the compression plates (8) against the cells (6) of the stack (7); and at least one elastic device (15) for compensating for gaps in the stack in the direction of dimensional change of the stack, the elastic device including at least one flat wire wave spring.

2. The battery (1) according to claim 1, wherein, Each elastic device (15) includes at least one spring (16) compressed between a pair of support members (17) substantially perpendicular to the direction of dimensional change of the stack (7).

3. The battery (1) according to claim 2, wherein, Each support member (17) includes a first surface (18) and a second surface (19), the first surface and the second surface being planar and opposite to each other, the second surface (19) being provided with a reinforcement (20) intended to accommodate the end of the compressed at least one spring (16).

4. The battery (1) according to any one of claims 1 to 3, wherein, At least one elastic device (15) includes at least one spring (16), the at least one spring of the at least one elastic device having an axial orientation oriented along the direction of the dimensional change of the stack (7).

5. The battery (1) according to any one of claims 1 to 4, wherein, At least one elastic device (15) includes a plurality of concentric springs (16) about the direction of dimensional change of the stack (7).

6. The battery (1) according to any one of claims 1 to 5, wherein, The support component (17) is made of an electrically insulating material.

7. The battery (1) according to any one of claims 2 to 6, wherein, Each of the adjacent support members (17) corresponding to the adjacent stack (7) includes a first hook (21) and a second hook (22), the first hook and the second hook being opposite to each other and aligned in a transverse direction perpendicular to the longitudinal axis (X) of the adjacent stack (7). The hooks (21, 22) have complementary U-shapes, thereby allowing the first hook (21) of the first support member to slide through the second hook (22) of the second support member adjacent to the first support member and allowing the pull rod (12) to pass through the hooks (21, 22) without hindering the relative translation of the adjacent support members in the direction of dimensional change of the stack (7).

8. The battery (1) according to any one of claims 1 to 7, wherein, The number of levers (12) is one more than the number of cell stacks (7).

9. An aircraft comprising a battery according to any one of claims 1 to 8.

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