Battery system, method of compensating battery system, and vehicle including battery system

Abstract

The invention relates to a battery system, a method of compensating the battery system, and a vehicle including the battery system. The battery system includes: a battery cell stack including a plurality of battery cells accommodated in compartments; and a compensator at an end portion of the battery cell stack to apply a pressing force on the battery cell stack. The compensator includes a flexible membrane bonded to a membrane carrier to define a variable volume configured to be filled with a fluid. The flexible membrane is configured to expand in response to an increase in fluid pressure in the compensator and contract in response to a decrease in fluid pressure in the compensator.

Description

Technical Field

[0001] Aspects of embodiments of the present disclosure relate to a battery system having a compensator, a method of compensating a battery system, and a vehicle including the battery system. Background Art

[0002] Recently, vehicles for transporting goods and people have been developed that use electricity as a source of locomotion. Such electric vehicles are vehicles propelled by an electric motor using energy stored in rechargeable batteries. Electric vehicles can be powered solely by batteries or by hybrid vehicles powered by, for example, a gasoline generator or a hydrogen fuel cell. Hybrid vehicles can include a combination of an electric motor and a conventional internal combustion engine. Typically, an electric vehicle battery (EVB or traction battery) is the battery used to power the propulsion of a battery electric vehicle (BEV). Electric vehicle batteries differ from starting batteries, lighting batteries, and ignition batteries in that they are designed to provide power for a sustained period of time. Rechargeable (or secondary) batteries differ from primary batteries in that they are designed to be repeatedly charged and discharged, while the latter are designed only to provide irreversible conversion of chemical energy into electrical energy. Low-capacity rechargeable batteries are used as power sources for small electronic devices such as cell phones, notebook computers, and camcorders, while high-capacity rechargeable batteries are used as power sources for electric vehicles and hybrid vehicles, etc.

[0003] Typically, a rechargeable battery includes an electrode assembly, a housing, and electrode terminals electrically connected to the electrode assembly, the electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and the housing receives (or accommodates) the electrode assembly. An electrolyte solution is injected into the housing to enable the battery to be charged and discharged via an electrochemical reaction of the positive electrode, the negative electrode, and the electrolyte solution. The shape of the housing (e.g., a cylindrical housing or a rectangular housing) depends on the intended purpose of the battery. Lithium-ion (and similar lithium polymer) batteries (best known through their use in laptop computers and consumer electronics) dominate the latest batch of electric vehicles under development.

[0004] Rechargeable batteries can be used as battery modules that are formed of (or include) a plurality of unit battery cells that are connected in series and / or in parallel to provide high energy density, such as for use in motor drives for hybrid vehicles. For example, a battery module can be formed by interconnecting the electrode terminals of a plurality of unit battery cells in an arrangement or configuration depending on the desired amount of power, thereby providing a high-power rechargeable battery.

[0005] The battery module can be configured in a block design or a modular design. In the block design, each battery is coupled to a common current collector structure and a common battery management system, and its units are arranged in a housing. In the modular design, multiple battery cells are connected together to form a sub-module, and several sub-modules are connected together to form a battery module. In automotive applications, the battery system typically includes multiple battery modules connected together in series to provide the desired voltage. The battery module may include a sub-module having a plurality of stacked battery cells, and each stack includes parallel-connected cells (XpYs) connected in series in sequence or series-connected cells (XsYp) connected in parallel in sequence.

[0006] A battery management system (BMS) can protect the battery pack from operating outside of its safe operating parameters. Operation outside of safe operating parameters can be indicated by overcurrent, overvoltage (e.g., during charging), overtemperature, undertemperature, overvoltage, and / or ground fault or leakage current detection. The BMS can prevent the battery from operating outside of its safe operating parameters by including an internal switch (e.g., a relay or solid-state device) that opens if the battery operates outside of its safe operating parameters, requests devices connected to the battery to reduce or even terminate use of the battery, and actively controls the environment (such as through heaters, fans, air conditioning, and / or liquid cooling).

[0007] The mechanical integration of this battery pack involves suitable mechanical connections between the individual components, such as between the battery modules and between the battery modules and the vehicle's support structure. These connections must be designed to remain functional and safe throughout the average service life of the battery system. Furthermore, installation space and interchangeability standards must be considered, particularly in mobile applications.

[0008] Mechanical integration of the battery module can be achieved by providing a carrier frame and positioning the battery module thereon. Securing the battery cells or battery module can be achieved by using mating recesses in the frame or by mechanical interconnects such as bolts or screws. In another example, the battery module can be restrained by fastening side panels to the lateral sides of the carrier frame. Cover plates can be secured on top and below the battery module.

[0009] The battery pack's carrier frame is attached to the vehicle's load-bearing structure. When the battery pack is secured to the vehicle's underbody, a mechanical connection can be established from the underside, for example, using bolts passing through the battery pack's carrier frame. The frame is typically made of aluminum or an aluminum alloy to reduce the overall weight of the assembly.

[0010] A battery system includes multiple battery cells and / or battery modules. Battery cells have a specific tolerance chain from the production itself. In a conventional arrangement, battery cells are stacked, squeezed (or compressed), and then placed in compartments. However, during their life and during charging or discharging, the width of the battery cells increases (called expansion). This expansion exerts additional forces on the battery cells or compartments. This expansion can lead to early failure or a reduction in the available energy density of the entire battery system. Summary of the Invention

[0011] The compensation system according to an embodiment of the present disclosure improves application of additional force caused by, for example, squeezing, which increases the lifespan of the battery cell and the battery system.

[0012] The present disclosure is defined by the appended claims and their equivalents. The following description is subject to such limitations. Any disclosure outside the scope of the claims and their equivalents is intended for illustrative and comparative purposes.

[0013] According to an embodiment of the present disclosure, a battery system includes at least one battery cell stack, which includes a plurality of battery cells housed in compartments. The battery system includes at least one compensator, each compensator being located at an end of a corresponding battery cell stack. The compensator includes a flexible membrane coupled to a membrane carrier to define a variable volume filled with a fluid. The flexible membrane is configured to expand in response to an increase in fluid pressure in the corresponding compensator and to contract in response to a decrease in fluid pressure in the corresponding compensator. One of the at least one compensator is positioned at an end of the at least one battery cell stack to apply a compressive force to the at least one battery cell stack.

[0014] Other aspects and features of the present disclosure will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Aspects and features of the present disclosure will become apparent to those skilled in the art by describing in detail embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0016] Figure 1 is a schematic side view of a battery system according to an embodiment;

[0017] Figure 2 is a schematic top view of a battery system according to an embodiment;

[0018] Figure 3 is a schematic cross-sectional view of a battery system including a compensator according to an embodiment;

[0019] Figure 4 is a schematic cross-sectional view of a battery system including a compensator according to another embodiment;

[0020] Figure 5 is a schematic cross-sectional view of a battery system including a compensator according to another embodiment;

[0021] Figure 6 is a schematic side view of a battery system according to another embodiment; and

[0022] Figure 7 is a flow chart describing a method of filling a battery system according to an embodiment. DETAILED DESCRIPTION

[0023] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. Aspects and features of the embodiments and methods for implementing the same will be described with reference to the accompanying drawings. However, the present disclosure may be implemented in a variety of different forms and should not be construed as limited to the embodiments illustrated herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and complete and will fully convey the aspects and features of the disclosure to those skilled in the art.

[0024] Therefore, processes, elements, and techniques that are not considered necessary for one of ordinary skill in the art to have a complete understanding of the aspects and features of the present disclosure may not be described or may be described only briefly.

[0025] It will be understood that when an element or layer is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it can be directly on, directly connected to, or directly coupled to the other element or layer, or one or more intervening elements or layers may be present. When an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers. For example, when a first element is described as being “coupled to” or “connected to” a second element, the first element can be directly coupled or connected to the second element, or the first element can be indirectly coupled or connected to the second element via one or more intervening elements.

[0026] In the accompanying drawings, the dimensions of various elements, layers, etc. may be exaggerated for clarity of illustration. The same reference numerals represent the same elements unless otherwise expressly stated. As used herein, the term "and / or" includes any and all combinations of one or more of the related enumerated items. In addition, when describing embodiments of the present disclosure, the use of "may" refers to "one or more embodiments of the present disclosure." Expressions such as "at least one of..." and "any of...", when following a list of elements, modify the entire list of elements, not the individual elements of that list. For example, the expression "at least one of a, b, or c" means only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof. As used herein, the terms "use," "using...", and "being used" may be considered synonymous with the terms "utilizing," "utilizing...", and "being utilized," respectively. As used herein, the terms "substantially," "approximately," and similar terms are used as approximate terms, rather than terms of degree, and are intended to illustrate the inherent variations in measured or calculated values ​​that would be recognized by those of ordinary skill in the art.

[0027] It will be understood that although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, the first element, component, region, layer or part discussed below can be referred to as a second element, component, region, layer or part without departing from the teachings of the example embodiments.

[0028] For ease of description, spatial relational terms such as "under," "below," "below," "above," "on," etc. may be used herein to describe the relationship of an element or feature to another element or feature as shown in the figures. It will be understood that, in addition to the orientations depicted in the figures, spatial relational terms are also intended to cover different orientations of the device in use or operation. For example, if the device in the figure is turned over, the elements described as being "under" or "under" other elements or features will be oriented to be "above" or "above" the other elements or features. Thus, the term "under" can cover both above and below orientations. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relational descriptors used here should be interpreted accordingly.

[0029] The terms used herein are intended to describe embodiments of the present disclosure and are not intended to limit the present disclosure. As used herein, the singular form "a" and "an" are also intended to include the plural form, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise," "comprising," "including," and / or "comprising," when used in this specification, indicate the presence of stated features, integers, steps, operations, elements, and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups thereof.

[0030] According to an embodiment of the present disclosure, a battery system includes at least one battery cell stack or a battery module including a plurality of battery cells housed in a compartment and at least one compensator. Each of the at least one compensator is located at an end of a corresponding battery cell stack. The compensator includes a flexible membrane coupled to a membrane carrier to define a variable volume, which is configured to be filled with a fluid. The flexible membrane is configured to expand in response to an increase in fluid pressure in the compensator and to contract in response to a decrease in fluid pressure in the compensator. One of the at least one compensator is positioned at or between the ends of the battery cell stack to apply a compressive force to the corresponding battery cell.

[0031] A battery cell stack comprising a plurality of battery cells housed in a compartment may also be referred to as a battery module. The end may be an end plate of a compartment or an end portion that separates two or more battery stacks in one compartment. Expansion may refer to an increase in volume, and contraction may refer to a decrease in volume. The flexible membrane may be made of a flexible material such as a flexible plastic or a flexible rubber material, but the present disclosure is not limited thereto. The flexible membrane may have a thin skin or material layer. The flexible membrane may be bent to at least partially define an interior space, and the fluid may be at least partially contained or collected in the interior space.

[0032] The compressive force generated by the fluid-filled flexible membrane, which exerts pressure on the battery cell stack, can equalize tolerances in the battery cell stack and can equalize expansion of the battery cells due to aging and / or charging / discharging. This is provided by the fluid, which exerts a compressive force on the battery cell stack via the flexible membrane. The compressive force provided by the flexible membrane increases the battery life of the battery system.

[0033] According to embodiments, a battery system includes multiple compensators that are fluidically connected to one another via, for example, a fluid manifold. The fluid manifold can be a reservoir, a fluid channel, or a fluid plate. The fluid manifold can be part of a fluid flow circuit. Due to the fluid connection between the compensators, compression forces can be equalized across different battery stacks. Furthermore, the filling or refilling process is simplified because each compensator does not need to be individually filled or refilled.

[0034] According to an embodiment, the fluid manifold is a cooling manifold or a cooling plate fluidly connected to a plurality of compensators, and the fluid is a coolant. Thus, in this embodiment, an existing structure of the battery system (i.e., the cooling plate included in the cooling circuit) can be used to provide a working medium for the compensator. Therefore, when using the coolant from the cooling plate, extra space is saved. Thus, aspects of the battery system according to embodiments of the present disclosure can also be easily retrofitted into existing systems.

[0035] According to an embodiment, the compensator includes a fluid inlet that includes a one-way inflow valve configured to allow fluid to flow into the flexible membrane when the pressure difference across the fluid inlet is higher than a first opening pressure. The fluid outlet includes a one-way outflow valve configured to allow fluid to flow out of the flexible membrane when the pressure difference across the fluid outlet is higher than a second opening pressure. The first opening pressure of the one-way inflow valve is lower than the second opening pressure of the one-way outflow valve.

[0036] The opening pressure is a valve characteristic and can be preset. The fluid inlet and the fluid outlet can be formed in the membrane carrier. With the above configuration including the two different valves as described above, a hysteresis effect can be generated, which can stabilize fluid flow variations. For example, the fluid in the flexible membrane can have a pressure (z) between a first opening pressure (x) and a second opening pressure (y). Then, the one-way inflow valve opens and the one-way outflow valve closes. In this case, pressure is applied to at least one battery cell stack. When overpressure occurs due to expansion in the battery stack (i.e., the pressure (u) of the fluid in the flexible membrane is greater than the second opening pressure (y)), the overpressure is released through the fluid outlet of the one-way outflow valve. Thus, the second opening pressure (y) serves as an overpressure protection mechanism because it defines the upper maximum pressure boundary. When the expansion decreases again, the pressure (u) will again decrease within the hysteresis (x < z < y). Thus, suitable operating conditions can be set for the battery system including the two one-way valves. Even when there is no filling pressure (e.g., ambient pressure), since the lower boundary (e.g., the first opening pressure (x)) prevents the fluid from flowing out at a lower pressure, the battery stack remains under tension, thereby retaining a small amount of fluid in the flexible membrane. This ensures that residual pressure is applied to the battery cell stack. Thus, aging or length changes during charging / discharging can be compensated, an overpressure protection feature is provided due to the pressure boundary, and a fluid retention feature is provided due to the pressure boundary.

[0037] According to an embodiment, the normal filling pressure or operating pressure is between the first opening pressure and the second opening pressure. Under normal circumstances, pressure is applied to at least one battery cell stack. This brings the battery system into a normal state / operation that benefits from the above-described boundaries. To provide stable operating conditions, the difference (i.e., hysteresis) between the first opening pressure (x) and the second opening pressure (y) can be relatively large.

[0038] According to an embodiment, each of the one-way inflow valve and the one-way outflow valve includes a spherical check valve, which includes a spring and a spherical member connected to the spring. The spherical member is configured to close the corresponding fluid inlet or fluid outlet when the pressure difference is lower than the corresponding opening pressure. Therefore, the opening pressure is set by the elastic spring. Accordingly, the elastic properties (e.g., stiffness) of the spring can be set or determined to define the relationship between the first opening pressure (x) and the second opening pressure (y) as described above. For example, the stiffness of the spring of the one-way inflow valve can be set to be lower than the stiffness of the spring in the one-way outflow valve.

[0039] According to embodiments, the fluid inlet and outlet are provided in the sidewalls of the membrane carrier. The fluid manifold includes a vertical connecting section that is fluidically connected to the fluid inlet and outlet. This allows for easy integration of a configuration including two one-way valves by utilizing side space. The vertical connecting section extends across the height of the battery cell stack.

[0040] According to an embodiment, the compensator includes a vertical inlet positioned between a planar fluid manifold and a flexible membrane. The vertical inlet provides a direct connection between the fluid manifold and the flexible membrane. This direct access to the interior of the flexible membrane allows for direct and automatic distribution of excess pressure. Furthermore, the vertical inlet reduces lateral space, resulting in a more space-efficient configuration. Furthermore, pressure regulation of excess pressure in the battery stack is directly distributed throughout the fluid system, eliminating the need for valves.

[0041] According to an embodiment, the vertical inlet has a cone shape. This provides a stable configuration because the cone shape ensures a tight seal when pressure is applied.

[0042] According to an embodiment, the membrane carrier includes two protruding portions protruding toward the battery cell stack. These portions are separated in the height direction (e.g., vertically). The flexible membrane is bonded to the membrane carrier so that the fluid fills the variable volume of the flexible membrane and the fixed space formed between the horizontal protruding portions. This configuration not only provides stable support for the flexible membrane, but also allows the contact area with the battery cell stack to be increased due to the lower curvature of the flexible membrane. This can be used to achieve a more uniform force acting on the corresponding battery cell stack.

[0043] According to an embodiment, the ends of the battery stack include end plates. The end plates are mounted so as to be movable relative to at least one compensator. By guiding (or moving) the end plates, this allows for more uniform contact with the battery cell stack and more efficient pressure transfer to the battery cell stack.

[0044] According to embodiments, the position control unit is configured to adjust the position of the end plate relative to the compensator. This allows for more uniform pressure across the battery cells in the battery stack. For example, the contact area between the flexible membrane and the battery stack can be increased. This adjustment can be based on contact area measurements or pressure determination.

[0045] According to an embodiment, one of the at least one compensator is located between two ends of adjacent battery cell stacks to apply a compressive force on the two battery cell stacks based on the fluid pressure in the flexible membrane. This allows the compensator to replace the separator or spacer between the battery cell stacks.

[0046] According to an embodiment, a method of filling a battery system as described above is provided. The method includes filling the flexible membrane with a pressure between a first opening pressure and a second opening pressure. The battery system thus enters an operating state in which the pressure applied to the battery cell stack is within the hysteresis described above.

[0047] The method may further comprise refilling the flexible membrane to a normal pressure between the first opening pressure and the second opening pressure when the pressure in the flexible membrane drops below the first opening pressure. Thus, stable operating conditions may be maintained through the refilling process.

[0048] According to an embodiment, there is provided a vehicle including the battery system as described above.

[0049] Figure 1 1 is a schematic side view of a battery system 100 according to an embodiment. The battery system 100 includes at least one battery cell stack 10. The battery cell stack 10 includes a plurality of battery cells 12. For example, Figure 1 As shown in FIG, the battery cells 12 may be prismatic battery cells, and they may be stacked accordingly. The battery cells 12 are housed in compartments (or frames) 16 to form a battery module. Of the components of the compartments 16, only the end plates 14 are in Figure 1 A plurality of spacers 11 may be provided between the battery cells 12, for example Figure 1 In addition, a housing 18 ( Figure 1 The battery cell stack 10 is integrated (eg, housed) in a housing 18 (only side walls of which are shown). However, the positioning is not limited to Figure 1 The end plates 14 provide boundaries for the battery cell stack 10, while other frame portions are not shown in this schematic diagram.

[0050] The battery system 100 also includes at least one compensator 20. The compensator 20 is located at the end 13 of the battery cell stack 10. In the illustrated embodiment, the compensator 20 is provided at (e.g., on or adjacent to) the end plate 14 of the battery cell stack 10. In other embodiments, the compensator 20 can be provided directly at the battery cell 12, for example, at a major surface of the battery cell 12.

[0051] like Figure 1 As shown in FIG, the compensator 20 includes a flexible membrane 22. The flexible membrane 22 may be bonded to a membrane carrier 26 (see, e.g., Figures 3 to 5 ). A membrane carrier (or membrane support) 26 may be located at the end 13 of the battery cell stack 10, such as at the end plate 14. The flexible membrane 22 and the membrane carrier 26 together define a variable volume 24 filled with a fluid. For example, the fluid may be water, but the present disclosure is not limited thereto.

[0052] The flexible membrane 22 is configured to expand in response to an increase (or rise) in the fluid pressure within the compensator 20. Thus, when the pressure within the compensator 20 increases, the variable volume 24 of the compensator 20 increases. Similarly, the flexible membrane 22 contracts in response to a decrease (or fall) in the fluid pressure within the compensator 20. Thus, when the pressure within the compensator 20 decreases, the variable volume 24 of the compensator 20 decreases. Thus, the compensator 20 is positioned at the end 13 of the battery cell stack 10 to apply a compressive force to the battery cell stack 10. The compressive force applied to the battery cell stack 10 depends on (or is controlled by) the fluid pressure within the compensator 20.

[0053] Due to the flexible membrane 22 and its pressure sensitivity, an adjustable pressure can be applied to the battery cell stack 10 , so that tolerances can be equalized by the fluid-containing compensator 20 including the flexible membrane 22 and expansion can be counteracted by the pressing force.

[0054] Figure 2 FIG is a schematic top view of a battery system 100 according to an embodiment. In this embodiment, the battery system 100 includes a plurality of compensators 20. The plurality of compensators 20 are fluidically connected to each other (e.g., fluidically communicated with each other) via a fluid manifold 60. The fluid manifold 60 is only in a Figure 2 The compensator 20 can be positioned at the end plate 14 or directly at one or more battery cells 12 at the end of the battery cell stack 10. Because the multiple compensators 20 are fluidly connected relative to each other via the fluid manifold 60, the compensating forces between different battery cell stacks 10, 10' can be equal (e.g., can be applied equally).

[0055] In addition, if Figure 2 As shown in FIG, the fluid manifold 60 may be a cooling manifold. Thus, the fluid may be a coolant liquid (such as water), but the present disclosure is not limited thereto. Thus, the existing structure of the battery system 100 may be used to cool the flexible membrane 22 and provide the flexible membrane 22 with a working fluid, and to exert pressure on the battery system 100. This increases compactness and retrofittability.

[0056] Figure 3 FIG2 is a schematic cross-sectional view of a battery system 100 including a compensator 20 according to an embodiment. Compensator 20 includes a fluid inlet 29. Fluid inlet 29 is formed in a membrane carrier (or membrane support) 26. Membrane carrier 26 includes a one-way inflow valve 30. One-way inflow valve 30 is configured to allow fluid to flow into flexible membrane 22 when the pressure difference across fluid inlet 29 exceeds a first opening pressure. Furthermore, one-way inflow valve 30 is configured to prevent fluid from flowing out of flexible membrane 22 through one-way inflow valve 30.

[0057] refer to Figure 3 Similar to the above description of the fluid inlet 29, the fluid outlet 29' includes a one-way outflow valve 30'. The one-way outflow valve 30' is configured to allow the fluid to flow out of the flexible membrane 22 when the pressure difference across the fluid outlet 29' is higher than the second opening pressure. In addition, the one-way outflow valve 30' is configured to prevent the fluid from flowing into the flexible membrane 22.

[0058] Furthermore, as will be described in more detail below, the first opening pressure of the one-way inlet valve 30 is lower than the second opening pressure of the one-way outlet valve 30'. Therefore, in this embodiment, the one-way valves 30, 30' are configured differently and open according to the applied pressure; that is, the first opening pressure of the one-way inlet valve 30 is lower than the second opening pressure of the one-way outlet valve 30'. Expansion of the battery cell 12 can be effectively mitigated by generating a hysteresis effect, which will be described in more detail below.

[0059] The fluid in the flexible membrane 22 may have a pressure (e.g., a pressure value) between the first opening pressure and the second opening pressure, for example, as a target pressure for the filling process. In this case, the one-way inflow valve 30 is open, and the one-way outflow valve 30' is closed. The compensator 20 is then in pressure equilibrium with the fluid manifold 60 and applies a compressive force to the battery cell stack 10.

[0060] Furthermore, if overpressure is caused, for example, by expansion of battery cells 12 in battery cell stack 10, the overpressure may be greater than the second opening pressure. In this case, the overpressure is released through one-way outflow valve 30' via fluid outlet 29' and distributed throughout the system. Thus, overpressure protection is provided by setting the second opening pressure accordingly.

[0061] Furthermore, when the expansion decreases again, the pressure within the compensator 20 will again be within the hysteresis range, that is, first opening pressure < current pressure < second opening pressure, so that the default or normal state is reestablished. The refill process can occur when the pressure in the battery cell stack 10 is lower than the first opening pressure. Even if the filling pressure (e.g., ambient pressure) does not exist, the battery cell stack 10 will remain under compression due to the lower boundary (e.g., the first opening pressure), thereby preventing the fluid from flowing out at a lower pressure, thereby maintaining a certain amount (e.g., a small amount) of fluid in the flexible membrane 22. This ensures that residual pressure is applied to the battery cell stack 10.

[0062] During normal operation, the normal setting is to set the pressure of the fluid between the first opening pressure and the second opening pressure. In order to provide stable operating conditions, the difference between the first opening pressure and the second opening pressure should be relatively large.

[0063] Thus, the configuration including two one-way valves 30, 30' facilitates length compensation within the battery cell stack 10 and compensates for length changes during aging (e.g., due to expansion) or during the charge / discharge process. Furthermore, this configuration prevents overpressure due to the upper pressure limit and also maintains residual pressure, thereby providing a compressive force to the battery cell stack 10 even in the absence of ambient pressure (e.g., no fill pressure).

[0064] The above conditions can exist in Figure 3 For example, each of the one-way inflow valve 30 and the one-way outflow valve 30' is (or includes) a ball check valve. The ball check valve includes a spring 32, 32' and a spherical member 33, 33' connected to the spring 32, 32'. The spherical member 33, 33' is configured to close the corresponding fluid inlet 29 or fluid outlet 29' when the pressure difference is lower than the corresponding opening pressure.

[0065] The fluid inlet 29 and the fluid outlet 29' can form a chamber in which a ball check valve is integrated. For example, a constriction 34, 34' can be provided, and the ball member 33, 33' can be pressed by or seated in the constriction 34, 34' by a spring 32, 32'. The spring 32, 32' can be mounted on an opposing wall 35, 35' of the chamber, opposite the constriction 34, 34', to provide a resilient pressing force against the constriction. As described above, as an example, the spring 32 can have a lower stiffness than the spring 32' to provide the relative opening pressure described above to generate hysteresis.

[0066] Furthermore, the flexible membrane 22 is fixed to the membrane carrier 26. For example, the ends of the flexible membrane 22 may be joined to the membrane carrier 26 by means of bolts or screws 37, 37'.

[0067] Furthermore, a fluid inlet 29 and a fluid outlet 29' are provided in the side wall 27 of the membrane carrier 26. Furthermore, a fluid manifold 60 includes a vertical connecting section 62 that is fluidically connected to the fluid inlet 29 and the fluid outlet 29'. Thus, a horizontal inlet is provided that uses the lateral space to provide a stable connection for the one-way inflow valve 30 and the one-way outflow valve 30'.

[0068] In addition, the membrane carrier 26 includes two protruding portions 28, 28' that protrude toward the battery cell stack 10 and are separated from each other in the height direction (e.g., Z direction). The flexible membrane 22 is bonded to the membrane carrier 26 so that the fluid fills the variable volume 24 of the flexible membrane 22 and the fixed space 25 formed between the protruding portions 28, 28'. Therefore, the flexible membrane 22 only has to cover half the space (e.g., only has to cover half of the lateral dimension of the compensator 20) and is stably supported by the membrane carrier 26. In addition, a more uniform pressure can be applied to the corresponding battery cell stacks 10, 10', in other words, the curvature of the flexible membrane 22 can be smaller. Therefore, a larger (side) area of ​​the battery cell stacks 10, 10' receives the pressing force to improve effective contact.

[0069] Figure 4 is a schematic cross-sectional view of a battery system 100 according to another embodiment of the compensator 20. In this embodiment, the main description is made with respect to Figure 3 The differences in the embodiments shown in .

[0070] The compensator 20 includes a vertical inlet 40 located between the fluid manifold 60 and the flexible membrane 22 (e.g. extending in the height direction of the battery cell stack 10, 10'). For example, the fluid manifold 60 is formed below the battery cell stack 10, 10'. The vertical inlet 40 includes a direct channel 42 connecting the fluid manifold 60 with the flexible membrane 22. In this embodiment, a membrane opening 23 is provided in the vertical inlet 40 to allow the fluid to pass through and enter the variable volume 24. Therefore, in this embodiment, no additional valve is used. Because the vertical inlet 40 includes a direct channel 42 to the inside of the flexible membrane 22, the overpressure is regulated directly and automatically. Therefore, when the pressure of the battery cell stack 10, 10' increases, any overpressure is directly released and distributed. In addition, due to the vertical inlet 40, the lateral space can be reduced to allow compact integration. In addition, the pressure regulation of the overpressure in the battery cell stack 10, 10' is directly distributed over the entire fluid system without the need for valves. In addition, in Figure 4 In the embodiment shown in FIG, the vertical inlet 40 has a cone shape 44. This cone shape (or cone surface) 44 ensures a tight seal when pressure is applied.

[0071] Figure 5is a schematic cross-sectional view of a battery system 100 according to another embodiment. In this embodiment, the compensator 20 is located between the two end portions 13 of adjacent battery cell stacks 10 and 10', so that the flexible membrane 22 exerts a pressing force on the two battery cell stacks 10 and 10' based on the fluid pressure in the flexible membrane 22. In this embodiment, the membrane carrier 26 can be centrally arranged between the end plates 14. Therefore, pressure can be applied to the two battery cell stacks 10 and 10', as shown in FIG. Figure 5 As shown in . Similar to Figure 4 In the embodiment shown in FIG, a vertical inlet 40 is provided. However, in other embodiments, the above Figure 3 The features described may be provided for centering to apply pressure in two directions. End plates 14 are provided, but compensators 20 may also be in direct contact with the major surfaces of the battery cells 12 .

[0072] Figure 6 is a schematic side view of a battery system 100 according to another embodiment. Figure 1 In this embodiment, the end plate 14 is mounted so as to be movable relative to the compensator 20. Thus, the end plate 14 can be guided. For example, Figure 6 As shown in FIG, the linear displacement of the end plate 14 can be controlled This allows for a constant pressure to be set across a region (e.g., a primary region) of the battery cell stack 10, 10'. For example, a more uniform pressure can be provided by adjusting the relative position of the end plate 14 relative to the compensator 20, i.e., the flexible membrane 22 can more smoothly and / or completely contact the end of the battery cell stack 10.

[0073] The position control unit 70 can be configured to adjust the position of the end plate 14 relative to the compensator 20 (via displacement). For example, the adjustment can be based on the detected pressure across the region of the battery cell stack 10, or by determining the contact area between the flexible membrane 22 and a region (e.g., a main region) of the battery cell stack 10, 10'. Thus, force transmission can be optimized and can be combined with any of the above-described embodiments.

[0074] Figure 7 1 is a flow chart describing a method of filling a battery system 100 according to an embodiment. The method includes providing a battery system 100 including a compensator 20 (S100). The battery system 100 may be as described above with respect to Figure 3 As described, it may include a one-way inflow valve 30 and a one-way outflow valve 30 ′.

[0075] The method further comprises filling the compensator 20 with a pressure between the first opening pressure (of the one-way inflow valve 30) and the second opening pressure (of the one-way outflow valve 30') (S200). Figure 3 This provides a normal operating state of the battery system 100 , with each battery cell stack 10 , 10 ′ being placed under compressive force.

[0076] The method may also include refilling the compensator 20 to a pressure between the first opening pressure and the second opening pressure (S300). This is performed when the pressure in the compensator 20 caused by the battery cell stack 10, 10' drops below the first opening pressure. A pressure sensor may be used to monitor the pressure and activate the pump / refill mechanism to reestablish normal operating conditions.

[0077] Thus, the method ensures that the battery system 100 remains in a healthy / working state and that the battery cell stacks 10, 10' remain under compressive pressure. For example, pressure control via a pressure sensor may be implemented to automatically detect when refilling occurs and cause the pump to reestablish pressure on the battery cell stacks 10, 10'.

[0078] In summary, according to various embodiments, the battery system 100 is provided with at least one compensator 20 that can apply a compressive force to at least one battery cell stack 10, 10' using fluid pressure. This mechanism allows for tolerance equalization and expansion compensation. According to various embodiments, compression is provided via multiple connected compensators. This allows for consistent compression of even different battery cell stacks 10, 10' and improves the operability of the battery system 100.

[0079] Some reference symbols

[0080] 100 battery system 10 battery cell stack

[0081] 10' battery cell stack 11 spacers

[0082] 12 Battery cell 13 End

[0083] 14 end plates 16 compartments

[0084] 18 Housing / housing wall 20 Compensator

[0085] 22 flexible membrane 23 membrane opening

[0086] 24 variable volume 25 fixed space

[0087] 26 membrane carrier 27 side wall

[0088] 28 protruding portion 28' protruding portion

[0089] 29 fluid inlet 29' fluid outlet

[0090] 30 one-way inflow valve 30' one-way outflow valve

[0091] 32 spring 32' spring

[0092] 33 spherical member 33' spherical member

[0093] 34 contraction portion 34' contraction portion

[0094] 35 opposite wall 35' opposite wall

[0095] 37 bolts / screws37' bolts / screws

[0096] 40 vertical entrance 42 direct access

[0097] 44 cone shape 60 fluid manifold

[0098] 62 vertical connection section 70 position control unit

[0099] S100 provides S200 filling

[0100] S300 refill.

Claims

1. A battery system comprising: a battery cell stack comprising a plurality of battery cells housed in compartments; as well as a compensator at an end of the battery cell stack to exert a pressing force on the battery cell stack, the compensator comprising a flexible membrane bonded to a membrane carrier to define a variable volume, the variable volume being configured to be filled with a fluid, The flexible membrane is configured to expand in response to an increase in fluid pressure in the compensator and to contract in response to a decrease in the fluid pressure in the compensator.

2. The battery system according to claim 1, further comprising: a plurality of said compensators; as well as A fluid manifold fluidly connects the plurality of compensators to each other. 3 . The battery system of claim 2 , wherein the fluid manifold comprises a cooling plate in fluid connection with the compensator.

4. The battery system according to claim 1, wherein the compensator comprises: a fluid inlet comprising a one-way inflow valve configured to allow fluid to flow into the flexible membrane when a pressure differential across the fluid inlet is above a first opening pressure; and a fluid outlet, comprising a one-way outflow valve configured to allow fluid to flow out of the flexible membrane when a pressure difference across the fluid outlet is greater than a second opening pressure, The first opening pressure of the one-way inflow valve is lower than the second opening pressure of the one-way outflow valve. 5 . The battery system according to claim 4 , wherein a normal filling pressure is a value between the first opening pressure and the second opening pressure.

6. The battery system according to claim 4, wherein each of the one-way inflow valve and the one-way outflow valve comprises a ball check valve including a spring and a spherical member connected to the spring, and The spherical member is configured to close the corresponding fluid inlet or fluid outlet when the pressure difference is lower than the corresponding opening pressure.

7. The battery system according to claim 4, wherein the fluid inlet and the fluid outlet are in a side wall of the membrane carrier, and The fluid manifold includes a vertical connecting section, the vertical connecting section being fluidically connected to the fluid inlet and the fluid outlet.

8. The battery system of claim 1 , wherein the compensator comprises a vertical inlet between a fluid manifold and the flexible membrane, and The vertical inlet comprises a direct channel connecting the fluid manifold and the flexible membrane.

9. The battery system according to claim 8, wherein the vertical inlet has a cone shape.

10. The battery system according to claim 1, wherein the membrane carrier has two protruding portions that are separated in a height direction and protrude toward the battery cell stack, and The flexible membrane is coupled to the membrane carrier such that the fluid fills the variable volume of the flexible membrane and the fixed spaces formed between the protruding portions.

11. The battery system of claim 1 , wherein end plates are at the ends of the battery cell stack, and The end plate is configured to be movable relative to the compensator. 12 . The battery system according to claim 11 , further comprising a position control unit configured to adjust a position of the end plate relative to the compensator.

13. A method of compensating a battery system, the battery system comprising: a battery cell stack comprising a plurality of battery cells housed in compartments; and a compensator at an end of the battery cell stack to exert a compressive force on the battery cell stack, the method comprising filling a flexible membrane of the compensator with a pressure between a first opening pressure and a second opening pressure. 14 . The method of claim 13 , further comprising refilling the compensator with a pressure between the first opening pressure and the second opening pressure when the pressure in the flexible membrane drops below the first opening pressure.

15. A vehicle comprising the battery system according to any one of claims 1 to 12.

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