Battery pack, preparation method thereof, and debonding detection method

Abstract

The present application relates to a battery pack and a preparation method thereof, and a debonding detection method. The battery pack includes a box body, a battery cell group stacked in sequence along the Z direction, a thermally conductive structural adhesive and a cold plate, as well as a flexible part and a filling part. The box body includes a bottom guard plate, and the Z direction is the thickness direction of the bottom guard plate. The flexible part is arranged on the bottom guard plate and supported on the side of the cold plate away from the thermally conductive structural adhesive. Along the Z direction, the projection of the flexible part overlaps with the projection of the battery cell group. A cavity is constructed inside the flexible part, and the cavity is loaded with fluid. The flexible part is constructed to expand and contract with changes in the fluid content in the cavity to adjust the supporting force of the flexible part on the cold plate. The filling part is connected to the cavity and can allow fluid to enter and exit the cavity to control the content of the fluid in the flexible part. The technical solution of the present application can not only improve the thermal management effect of the battery pack, but also monitor whether the battery pack is debonded during use, thereby improving its reliability.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery pack, a preparation method thereof, and a debonding detection method. Background Art

[0002] A battery pack typically includes a housing, multiple cell groups within the housing, and a cold plate. The cold plate exchanges heat with the cell groups to achieve thermal management of the battery pack. Taking into account factors such as cell size tolerance and cell stacking tolerance, a downward pressure mechanism is usually used to apply a certain downward pressure to the cell group during battery pack assembly to ensure smooth insertion. When pressure is applied to the cell group, the cold plate at the bottom of the battery pack is squeezed by the cell group, and is prone to local concavity. This results in uneven thickness of the thermally conductive structural adhesive between the cold plate and the cell group, affecting the thermal management of the battery pack. Summary of the Invention

[0003] Based on this, it is necessary to provide a battery pack and its preparation method, and a debonding detection method to address the problem of uneven thickness of the thermal conductive structural adhesive between the cold plate and the battery cell group, which affects the thermal management effect of the battery pack.

[0004] In a first aspect, the present application provides a battery pack, comprising:

[0005] Box body, including bottom guard plate;

[0006] The battery cell group, the thermal conductive structural adhesive and the cold plate are stacked in sequence along the Z direction, wherein the Z direction is the thickness direction of the bottom guard plate; and

[0007] a flexible member disposed on the bottom guard plate and supported on a side of the cold plate facing away from the thermally conductive structural adhesive; along the Z direction, the projection of the flexible member overlaps with the projection of the battery cell group; the flexible member has a cavity configured therein, the cavity being filled with a fluid; the flexible member is configured to expand and contract with changes in the fluid content in the cavity to adjust the supporting force of the flexible member on the cold plate; and

[0008] A filling piece is communicated with the cavity and can allow the fluid to flow into and out of the cavity so as to control the content of the fluid in the flexible piece.

[0009] In some embodiments, the flexible member and the battery cell group are both configured in plurality; in the Z direction, the flexible member is arranged one-to-one with each battery cell group;

[0010] There are multiple filling pieces, and the cavity of each flexible piece is independently connected to one of the filling pieces via a pipeline.

[0011] In some embodiments, the flexible member includes an elastically expandable support frame, and the cold plate is supported on the support frame;

[0012] The cavity is located in the support frame, and the support frame has an initial volume. When the fluid causes the volume of the cavity to exceed the initial volume, the support frame is squeezed by the fluid and expands to increase its volume.

[0013] In some embodiments, the flexible member further includes an elastic sac forming the cavity, and the elastic sac is located within the support frame; the volume of the elastic sac can change with the content of the fluid inside. When the fluid causes the volume of the elastic sac to exceed the initial volume, the support frame is squeezed by the elastic sac and expands to increase its volume.

[0014] In some embodiments, a plurality of the elastic bags are provided in the support frame, and all the elastic bags are sequentially spaced and arranged along the X direction, where the X direction is the length direction of the bottom guard plate.

[0015] In some embodiments, each of the elastic bags in the same support frame is independently connected to the filling piece via a pipeline.

[0016] In some embodiments, the support frame includes a partition portion, wherein the partition portion is separated between adjacent elastic bladders;

[0017] The partition portion includes a partition groove recessed in the outer surface of the support frame. The partition groove extends along a Y direction intersecting with the X direction. The Y direction is a width direction of the bottom guard plate.

[0018] In some embodiments, the battery cell group includes an explosion-proof valve, which is located on a side of the battery cell group facing the cold plate along the Z direction, and the thermal conductive structural adhesive avoids the explosion-proof valve;

[0019] The cold plate is provided with an avoidance portion, the flexible member is provided with a thinning portion, the explosion-proof valve, the avoidance portion and the thinning portion are correspondingly arranged along the Z direction; the avoidance portion and the thinning portion are configured to allow the high-temperature and high-pressure flue gas released when the explosion-proof valve is depressurized to flow;

[0020] The fluid filled in the cavity includes a fire extinguishing substance, and the thinned portion allows high-temperature and high-pressure smoke to enter the cavity to be cooled by the fire extinguishing substance.

[0021] In some embodiments, the filling member includes a valve body, a core body, a ejector pin and a sealing plug, the valve body has a through hole, and the core body, the ejector pin and the sealing plug are all arranged in the through hole;

[0022] A core cavity is provided in the core body, the ejector pin passes through the core cavity and is movable relative to the core body in the depth direction of the through hole;

[0023] The sealing plug is fixed to the ejector pin and can open and close the core cavity when moving with the ejector pin.

[0024] In some embodiments, the battery pack further includes a monitoring device and a pressure detection component, wherein the pressure detection component is used to determine the supporting force provided by the fluid in the cavity to the cold plate, and the monitoring device is communicatively connected to the pressure detection component to determine whether the battery pack is debonded based on the detection results obtained by the pressure detection component.

[0025] In a second aspect, the present application provides a method for preparing a battery pack, which is applied to the battery pack described in any of the above embodiments, and the method comprises:

[0026] In the process of pressing the battery cell group into the box body by using the pressing mechanism, detecting the downward force exerted by the pressing mechanism on the cold plate through the battery cell group;

[0027] According to the downward force, a power pump connected to the filling member is controlled to inject the fluid into the cavity until the fluid in the cavity of the flexible member provides a supporting force to the cold plate that is equivalent to the downward force.

[0028] In a third aspect, the present application provides a battery pack debonding detection method, which is applied to the battery pack described in any of the above embodiments. The debonding detection method includes:

[0029] monitoring fluctuations in the supporting force provided by the fluid in the cavity of the flexible member to the cold plate;

[0030] When the fluctuation of the supporting force exceeds the allowable fluctuation range, it is determined that the battery pack is debonded;

[0031] Output degumming prompt information.

[0032] Compared with the prior art, this application has the following beneficial effects:

[0033] In the battery pack and its preparation method, as well as the debonding detection method, during the battery pack assembly process, after the flexible member and cold plate are placed inside the box, thermally conductive adhesive is applied to the upper surface of the cold plate. During the process of loading the battery cell group into the box, a downward pressure mechanism is used to apply downward pressure to the battery cell group, and this downward pressure is transmitted to the cold plate. At this time, the fluid supply device can adjust the fluid content in the cavity through the filling member so that the supporting force provided by the flexible member to the cold plate is substantially equivalent to the downward pressure exerted on the cold plate. The cold plate can be subjected to balanced force above and below, avoiding local concavity of the cold plate. This ensures that the thermally conductive structural adhesive filled between the cold plate and the battery cell group is evenly distributed and has a substantially uniform thickness during the downward pressure of the battery cell group, thereby achieving uniform heat exchange between the cold plate and the battery cell group and improving the thermal management effect of the battery pack.

[0034] In addition, the fluctuation of the supporting force provided by the fluid in the flexible part to the cold plate can be used to determine whether the battery pack is debonded, so that abnormal conditions of the battery pack can be discovered in time, thereby improving the reliability of the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0036] Figure 1 Schematic diagram of the appearance of the battery pack in some embodiments.

[0037] Figure 2 for Figure 1 Schematic diagram of the battery pack shown.

[0038] Figure 3 for Figure 1 Schematic diagram of the internal partial structure of the battery pack shown.

[0039] Figure 4 Schematic diagram of the connection between flexible parts and pipelines in some embodiments.

[0040] Figure 5 for Figure 4 A perspective view of the structure shown.

[0041] Figure 6 for Figure 1 Another orientation view of the battery pack is shown.

[0042] Figure 7 for Figure 6 Enlarged view of point A in the middle.

[0043] Figure 8 Schematic diagram of the structure of the filling piece in some embodiments.

[0044] Figure 9 Schematic diagram of the assembly process of a battery pack in some embodiments.

[0045] Figure 10 Schematic diagram of a process for preparing a battery pack according to some embodiments.

[0046] Figure 11 Schematic diagram of the process of detecting debonding of a battery pack in some embodiments.

[0047] The accompanying drawings in the specific implementation manner are as follows:

[0048] 100, battery pack; 10, box body; 11, bottom guard plate; 11a, accommodating groove; 12, filling piece; 12a, core body; a1, core cavity; a11, first cavity section; a12, second cavity section; 12b, ejector pin; b1, shoulder; 12c, sealing plug; 12d, elastic member; 12e, valve body; e1, through hole; 20, battery cell group; 30, thermal conductive structural adhesive; 40, cold plate; 40a, avoidance part; 41, upper plate; 42, lower plate; 50, flexible member; k, cavity; 51, support frame; 52, elastic bag; 53, partition; 53a, partition groove; 54, thinning part; 60, end plate; G, pipeline; 200, pressing mechanism; 300, clamping mechanism. DETAILED DESCRIPTION

[0049] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0050] In the description of the present application, it should be understood that, if any, terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0051] Furthermore, if used, the terms "first" and "second," if present, are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0052] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connected," and "fixed" should be interpreted broadly. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components, unless otherwise expressly limited. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0053] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0054] It should be noted that, if present, when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0055] This application addresses the technical problem pointed out in the background technology that during the assembly of the battery pack, when pressure is applied to the battery cell group, the cold plate located at the bottom of the battery pack is squeezed by the battery cell group, which is prone to local depression, resulting in uneven thickness of the thermal conductive structural adhesive filled between the cold plate and the battery cell group, thereby affecting the thermal management effect of the battery pack. A battery pack is proposed.

[0056] The battery packs involved in the embodiments of the present application include at least one battery cell group. Each battery cell group includes multiple battery cells arranged side by side. A battery cell is the smallest unit in a battery that performs an electrochemical reaction and can be a secondary battery or a primary battery. The battery cell can be, but is not limited to, a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery. The battery cell can be cylindrical, flat, rectangular, or in other shapes.

[0057] In one embodiment, a battery cell includes a housing, an end cap, and an electrode assembly. The housing and the end cap together form an interior space for accommodating the electrode assembly. Specifically, the housing may have a cavity formed therein, with at least one end being open. The end cap fits over the open end of the housing to seal the cavity, and the electrode assembly is loaded within the cavity. The housing may be, but is not limited to, a metal housing, such as an aluminum housing or a steel housing.

[0058] An electrode assembly typically consists of a positive electrode sheet, a negative electrode sheet, and a separator separating the two. An electrolyte is injected into the battery cell, which soaks into the electrode assembly, providing a pathway for ion migration for electrochemical reactions and acting as a conductor. Electrode assemblies can be wound or stacked. A battery cell can contain one or more electrode assemblies.

[0059] The battery pack in the embodiment of the present application is described in detail below.

[0060] Please refer to Figure 1 、 Figure 2 and Figure 3 The battery pack 100 in the embodiment of the present application includes a case 10, a battery cell group 20, a thermally conductive structural adhesive 30 and a cold plate 40 stacked in sequence along the Z direction, a flexible part 50 and a filling part 12. The case 10 includes a bottom guard plate 11, and the Z direction is the thickness direction of the bottom guard plate 11. The flexible part 50 is arranged on the bottom guard plate 11 and is supported on the side of the cold plate 40 away from the thermally conductive structural adhesive 30. Along the Z direction, the projection of the flexible part 50 overlaps with the projection of the battery cell group 20. A cavity k is constructed inside the flexible part 50, and the cavity k is loaded with fluid. The flexible part 50 is constructed to expand and contract with changes in the fluid content in the cavity k to adjust the supporting force of the flexible part 50 on the cold plate 40. The filling part 12 is connected to the cavity k and can allow fluid to enter and exit the cavity k to control the content of the fluid in the flexible part 50.

[0061] The bottom guard plate 11 can serve as the bottom plate of the box body 10, and is used to close the bottom of the box body 10. The bottom guard plate 11 can be a flat plate structure, or its bottom can protrude outward to form a concave plate structure. In a state of use, the thickness direction of the bottom guard plate 11 corresponds to the vertical direction. The flexible part 50, the cold plate 40, the thermal conductive structural adhesive 30 and the battery cell group 20 are arranged and supported on the bottom guard plate 11 in sequence from bottom to top. In one embodiment, the box body 10 also includes side panels and a cover plate. The side panels are arranged around the outer periphery of the bottom guard plate 11, and the two together form a storage space with an open end. The cold plate 40, the battery cell group 20, and the flexible part 50 are loaded into the storage space through the opening, and the cover plate covers the opening of the storage space.

[0062] The cold plate 40 is plate-shaped and has channels for a heat exchange medium. The heat exchange medium sequentially passes through the cold plate 40, the thermally conductive adhesive 30, and the battery cell group 20 to exchange heat, thereby regulating the temperature of the battery cell group 20. The thermally conductive adhesive 30 fills the space between the cold plate 40 and the battery cell group 20, ensuring uniform heat exchange between them.

[0063] A plurality of cell groups 20 are usually arranged on the upper side of the cold plate 40. The cells in each cell group 20 are arranged side by side in the same direction, and each cell group 20 is thermally connected to the cold plate 40 via a thermally conductive structural adhesive 30. The flexible member 50 is supported on the bottom of the cold plate 40 to provide support to the cold plate 40. In the Z direction, the projection of the flexible member 50 overlaps with the projection of the cell group 20. The portion of the cold plate 40 pressed down by the cell group 20 can be effectively supported by the flexible member 50, thereby preventing the cold plate 40 from being concave by the cell group 20. Optionally, one or more flexible members 50 may be arranged under each cell group 20. Alternatively, the same flexible member 50 may be arranged under all cell groups 20. Regardless of the arrangement of the cell group 20 and the flexible member 50, preferably, the projection of the cell group 20 along the Z direction is within the projection range of the flexible member 50, which can effectively ensure that the force on the cold plate 40 is uniform.

[0064] The flexible member 50 is a hollow structure with a cavity k inside. This cavity k contains a fluid, which can be a gas (such as nitrogen, carbon dioxide, air), a liquid (such as water), or a mixture thereof. Optionally, the fluid is a liquid, which is nearly incompressible and provides more stable and reliable support. The flexible member 50 is made of a flexible material that can expand and contract with changes in the fluid content within the cavity k. Specifically, the flexible member 50 can be made of rubber, thermoplastic polyurethane (TPU), ethylene tetrafluoroethylene copolymer (ETFE), polyethylene (PE), polypropylene (PP), aluminum-plastic film, ethylene propylene diene terpolymer (EPDM), etc. When the fluid content within the cavity k is high, the flexible member 50 is stretched outward by the fluid, providing greater support to the cold plate 40. When the fluid content within the cavity k is low, the flexible member 50 elastically retracts, reducing its support for the cold plate 40.

[0065] The filling member 12 can be disposed outside and / or inside the housing 10. The flexible member 50 is provided with an interface corresponding to the cavity k. The filling member 12 is connected to the interface of the flexible member 50 via a pipeline G. An external fluid supply device can inject fluid into the cavity k via the filling member 12, and / or the fluid in the cavity k can flow back to the fluid supply device via the filling member 12. In actual application, the fluid supply device can change the fluid content in the cavity k through the filling member 12, thereby changing the supporting force provided by the flexible member 50.

[0066] During the assembly of the battery pack 100, after the flexible member 50 and the cold plate 40 are placed inside the housing 10, thermally conductive adhesive is applied to the upper surface of the cold plate 40. As the cell group 20 is loaded into the housing 10, downward pressure is applied to the cell group 20 using the downward pressure mechanism 200, which is then transmitted to the cold plate 40. At this point, the fluid supply device can adjust the fluid content within the cavity k through the filling member 12, so that the supporting force provided by the flexible member 50 to the cold plate 40 is substantially equivalent to the downward pressure exerted on the cold plate 40. This allows for balanced force on the upper and lower parts of the cold plate 40, preventing localized concavity of the cold plate 40. The thermally conductive structural adhesive 30 filled between the cold plate 40 and the cell group 20 is evenly distributed and has a substantially uniform thickness during the downward pressure of the cell group 20, ensuring uniform heat exchange between the cold plate 40 and the cell group 20, thereby improving the thermal management of the battery pack 100.

[0067] Understandably, the filling member 12 can be provided during assembly of the battery pack 100 to allow the fluid supply device to fill the cavity k of the flexible member 50 with fluid. After assembly of the battery pack 100 is complete, the filling member 12 is disconnected from the fluid supply device and is sealed to prevent leakage of the fluid within the battery pack 100.

[0068] In some embodiments, multiple flexible members 50 and multiple cell groups 20 are provided. In the Z direction, each cell group 20 is provided with a corresponding flexible member 50. Since there may be some spacing between the cell groups 20, a flexible member 50 is provided below each cell group 20. This not only reduces the number of flexible members 50 and simplifies production layout, but also reduces the overall area used by the flexible members 50, thereby reducing costs.

[0069] It is worth mentioning that in actual application, the position of the flexible member 50 relative to the cell group 20 can be designed based on the location of the pressure applied by the pressing mechanism 200 on the cell group 20. Specifically, the flexible member 50 is arranged at least below the location of the pressure applied to the cell group 20. This eliminates the need for the projection of the cell group 20 to fall entirely within the projection of the flexible member 50. The flexible member 50 not only effectively provides support but also reduces the area used by the flexible member 50, thereby lowering costs.

[0070] In some embodiments, multiple filling members 12 are configured, and each cavity k of the flexible member 50 is independently connected to a filling member 12 via a pipe G. In this way, each filling member 12 can simultaneously fill or drain fluid from each flexible member 50, accelerating the fluid filling / draining speed of the entire battery pack 100. This allows the flexible members 50 to more quickly achieve the required supporting force, allowing the cold plate 40 to more quickly achieve a state of balanced upper and lower stress, reducing the probability of denting. Furthermore, each filling member 12 integrates the dual functions of fluid entry and exit from cavity k, reducing the number of filling members 12 and lowering costs.

[0071] In other embodiments, multiple flexible members 50 may share one filling member 12, or multiple filling members 12 may be connected to the cavity k of one flexible member 50 via a pipe G. When each cavity k is connected to multiple filling members 12, some of the filling members 12 may be used to allow fluid to flow into the cavity k, while the remaining filling members 12 may be used to allow fluid to flow out of the cavity k.

[0072] In some embodiments, reference Figure 4 The flexible member 50 is connected to the filling member 12 in a one-to-one correspondence, and the same flexible member 50 is connected to its own cavity k and the corresponding filling member 12 via multiple pipes G.

[0073] The location on the flexible member 50 that connects to the pipeline G is positioned as an interface. The flexible member 50 is provided with multiple interfaces that are connected one by one to each pipeline G. In this case, fluid can enter and exit the flexible member 50 through the multiple interfaces on each flexible member 50, increasing the filling and discharge rates of the fluid in each flexible member 50, and the flexible member 50 can provide the required support force more quickly.

[0074] The number of cavities k in each flexible member 50 can be one or more. When the number of cavities k is one, the fluid can synchronously enter and exit multiple positions of the cavity k through each interface, thereby accelerating the fluid in and out of the cavity k. When the number of cavities k is multiple, at least one interface is set corresponding to each cavity k, and the fluid enters and exits each cavity k through each interface. The fluid in each cavity k can enter and exit synchronously, and the flexible member 50 can also quickly provide the required supporting force. It can be understood that each cavity k can be connected to at least one interface. When there are multiple cavities k, the number of interfaces connected to each cavity k is the same, which is conducive to keeping the fluid in and out rates of each cavity k basically consistent.

[0075] In other embodiments, if the flexible member 50 includes multiple cavities k, and the cavities k are connected to each other, an interface may be provided on the flexible member 50 corresponding to one or part of the cavities k, so that fluid can enter and exit the cavities k.

[0076] In some embodiments, combined Figure 4 It is understood that the flexible member 50 includes an elastically expandable support frame 51, and the cold plate 40 is supported by the support frame 51. The cavity k is located within the support frame 51, and the support frame 51 has an initial volume. When the fluid causes the volume of the cavity k to exceed the initial volume, the support frame 51 is squeezed and expanded by the fluid, thereby increasing its volume.

[0077] The support frame 51 forms the outer shape of the flexible member 50. Specifically, the interior of the support frame 51 is hollow and has an initial volume. It can elastically expand based on the initial volume and basically return to the initial volume after the expansion disappears. Before the battery cell group 20 is loaded into the box 10, when the cold plate 40 is supported on the support frame 51, the support frame 51 basically maintains its initial volume under the action of the gravity of the cold plate 40, that is, the rigidity of the support frame 51 supports its support for the cold plate 40. In addition, when the support frame 51 is in the initial volume, it remains in a state of slight outward expansion, so as to compensate for the assembly gap between the support frame 51 and the cold plate 40 when supporting the cold plate 40, and play a flexible supporting role for the cold plate 40, thereby not only avoiding the depression of the cold plate 40 during assembly, but also playing a buffering role for the cold plate 40 during the use of the battery pack, and avoiding deformation of the cold plate 40 caused by vibration and impact.

[0078] Cavity k is located within support frame 51. Specifically, the interior space of support frame 51 can be used directly as cavity k, and cavity k has a minimum volume, namely, the initial volume. When the fluid content within cavity k exceeds the initial volume, the fluid squeezes support frame 51, causing it to expand, increasing both the volume of support frame 51 and the volume of cavity k. When the fluid content within cavity k does not exceed the initial volume, the fluid cannot squeeze support frame 51, and support frame 51 remains substantially at its initial volume.

[0079] When the support frame 51 is maintained at its initial volume, the flexible member 50 maintains its shape and prevents collapse. This allows the cold plate 40 to rest stably on the flexible member 50 before the battery pack 20 is loaded and the fluid is not yet filled or insufficiently filled (so that the fluid does not squeeze the support frame 51). This effectively supports the cold plate 40, preventing it from tilting or becoming unstable. This in turn helps even out the thickness distribution of the thermally conductive adhesive 30 applied to the cold plate 40.

[0080] In order to ensure that the support frame 51 is flexible and expandable and can basically maintain its initial volume when the fluid is not squeezed, one means of achieving this is to use a flexible material with relatively high rigidity for the support frame 51, such as fiber-reinforced rubber or TPU. In this case, the support frame 51 may undergo a certain deformation due to the gravity of the cold plate 40, but its internal volume basically remains at the initial volume, and it can effectively support the cold plate 40. Another means of achieving this is to provide the side and / or bottom surfaces of the support frame 51 with a structure that enhances rigidity (such as reinforcing ribs) or a coating (such as a metal coating or a ceramic coating), or to directly use a rigid material, as long as the top surface supporting the cold plate 40 is easy to expand and deform. Furthermore, the above-mentioned structure, coating, etc. that enhances rigidity can also be provided on the top surface of the support frame 51 to further enhance its rigidity while ensuring that it has a certain degree of flexibility and can expand and deform.

[0081] In some embodiments, combined Figure 5It is understood that the flexible member 50 also includes an elastic capsule 52 forming a cavity k. The elastic capsule 52 is located in the support frame 51. The volume of the elastic capsule 52 can change with the content of the internal fluid. When the fluid causes the volume of the elastic capsule 52 to exceed the initial volume, the support frame 51 is squeezed by the elastic capsule 52 and expands to increase its volume.

[0082] The elastic bladder 52 can be understood as an airbag structure, capable of expanding and contracting with increases and decreases in fluid content. When the fluid content within the bladder 52 does not cause its volume to exceed its initial volume, the elastic bladder 52 cannot squeeze the support frame 51, and the cold plate 40 relies primarily on the support frame 51 to support it. When the fluid content within the elastic bladder 52 increases, causing its volume to exceed its initial volume, the elastic bladder 52 expands and squeezes the support frame 51. Under the pressure of the elastic bladder 52, the support frame 51 elastically expands and deforms, thereby increasing its support for the cold plate 40. In other words, when the volume of the elastic bladder 52 exceeds the initial volume of its accommodating cavity, the support frame 51 expands and deforms with the elastic bladder 52 (increasing the volume of the accommodating cavity). When the squeezing effect of the elastic bladder 52 disappears, the support frame 51 essentially returns to its initial volume.

[0083] It is understandable that the rigidity of the elastic member 12d is less than that of the support frame 51 , and it can be made of a flexible material with less rigidity, such as aluminum-plastic film, silicone rubber, EPDM, etc., which is easily deformed by the action of fluid.

[0084] At this time, the elastic sac 52 forms a cavity k within the support frame 51. On the one hand, the provision of the elastic sac 52 facilitates the formation of multiple independent cavities k within the support frame 51, and has good sealing performance for the fluid, effectively preventing the fluid from leaking out and causing electrical safety issues. On the other hand, because the elastic sac 52 can expand and contract with the increase or decrease of the fluid content, it can more accurately monitor the pressure generated by the fluid in the cavity k, making the fluid pressure in the flexible member 50 precisely controllable, thereby facilitating more accurate determination of the support force provided by the flexible member 50, ensuring uniform force on the upper and lower parts of the cold plate 40. In addition, multiple independent cavities k can more accurately monitor the pressure at different locations of the cold plate 40, further facilitating improved force uniformity at different locations of the cold plate 40.

[0085] In other embodiments, the flexible member 50 itself may also be formed only by the above-mentioned elastic bag 52. In order to enable the flexible member 50 to maintain a certain shape to effectively support the cold plate 40, a certain amount of fluid can be pre-stored in the elastic bag 52, and at least this amount of fluid can be retained in the elastic bag 52 during the process of the fluid entering and exiting the cavity k.

[0086] In the above embodiment, the addition of a support frame 51 outside the elastic bladder 52 provides the aforementioned benefits. Because the support frame 51 acts as a qualitative constraint, no fluid is required within the elastic bladder 52. This reduces the weight of the flexible member 50 during assembly, making assembly more labor-efficient. Furthermore, the fluid filling step can be omitted during production, simplifying production while ensuring precise control of the fluid pressure within the flexible member 50.

[0087] Preferably, the support frame 51 is insulating and can insulate the cold plate 40 from the bottom guard plate 11, reducing the risk of the bottom guard plate 11 becoming charged when the battery pack 20 leaks electricity. When the elastic bag 52 is made of a conductive material such as aluminum-plastic film, the support frame 51 can also serve as an insulating elastic bag 52.

[0088] In some embodiments, as Figure 5 As shown, a plurality of elastic bladders 52 are provided in the support frame 51, and all the elastic bladders 52 are sequentially spaced and arranged along the X direction, which is the length direction of the bottom guard plate 11. Each elastic bladder 52 in the same support frame 51 is independently connected to the filling piece 12 via a pipeline G.

[0089] In actual application, the battery cells in the battery cell group 20 can be arranged side by side along the length direction of the bottom guard plate 11 , or can be arranged side by side along the width direction of the bottom guard plate 11 .

[0090] The support frame 51 extends longitudinally in the X-direction and contains multiple elastic bladders 52 arranged sequentially along the X-direction. Each elastic bladder 52 can be positioned to correspond to a different pressure-applying location on the same cell group 20 or to different pressure-applying locations on different cell groups 20. The provision of multiple elastic bladders 52 allows each flexible member 50 to provide zoned support for each pressure-applying location, resulting in improved support and more evenly distributed force on the cold plate 40.

[0091] The supporting forces provided by each elastic bladder 52 may be the same or different. In some embodiments, at least some of the elastic bladders 52 provide different supporting forces. For example, an elastic bladder 52 with greater supporting force may be provided in the central region of the battery cell group 20 or the region where the battery cell group 20 is located. Designing elastic bladders 52 with different supporting forces can be conventionally designed based on factors such as the fluid content within the bladder 52, the material of the bladder 52, and the shape and size of the bladder 52, which will not be discussed in detail here.

[0092] It is worth mentioning that when the battery cell group 20 is assembled, in order to improve the uniformity of pressure application, pressure is applied to the middle area of ​​the battery cell group 20 or the battery cell group 20 located in the middle, so that the depression phenomenon in the middle area of ​​the battery cell group 20 or the cold plate 40 area corresponding to the battery cell group 20 located in the middle is more serious. At this time, the support force here can be increased by designing an elastic bag 52 with a larger support force, thereby improving the uniformity of force on the cold plate 40 and the consistency of the thickness of the thermal conductive structural adhesive, thereby improving the heat exchange effect. In addition, when the cold plate 40 is fixed to the box 10 on all sides, when the middle area of ​​the cold plate 40 is pressurized, a greater stress concentration will be generated due to the boundary constraint, and the middle area is more likely to cause depression. At this time, an elastic bag 52 with a larger support force is set corresponding to the middle area of ​​the cold plate 40, which can increase the support force here and further improve the uniformity of force on the cold plate 40.

[0093] It should be noted that the middle area of ​​the cold plate 40 is called the first area, and the middle area of ​​the cold plate 40 corresponding to the battery cell group 20 or the area corresponding to the battery cell group 20 located in the middle is called the second area. The first area and the second area can be different, and the set support force can be different. At this time, the support force of the two areas can be set as needed to reduce the uneven force caused by different deformations; in another embodiment, the first area and the second area can also be the same. At this time, under the dual action, the sinking phenomenon of the cold plate 40 is particularly serious, and the support force here can be further increased to avoid the sinking phenomenon of the cold plate 40 and ensure the uniformity of the force on the cold plate 40.

[0094] In a specific embodiment, each elastic bladder 52 within the same support frame 51 is independently connected to the filling member 12 via a pipeline G. Specifically, each elastic bladder 52 can be connected to a different filling member 12, or to the same filling member 12. Optionally, each elastic bladder 52 within the same support frame 51 can be connected in parallel to the same filling member 12. This can reduce the number of filling members 12 and simultaneously allow each elastic bladder 52 to be filled with fluid, resulting in higher fluid filling efficiency. The partitions where each elastic bladder 52 is located can basically provide support force to each pressure application location simultaneously, preventing the cold plate 40 from being depressed due to insufficient local support.

[0095] It is worth noting that when the elastic bladders 52 of the same support frame 51 are connected in parallel to the same filling member 12, the amount of fluid flowing into the elastic bladders 52 at the same time can be controlled by designing the inner diameter of the pipe G connected to the elastic bladders 52, thereby controlling the supporting force provided by the elastic bladders 52, thereby varying the supporting force provided by at least some of the elastic bladders 52. The supporting force is equal to the product of pressure and contact area. Optionally, when filled with the same amount of fluid, the supporting force provided by each elastic bladder 52 can be varied by designing the size of the elastic bladders 52 to achieve different pressures and by appropriately designing the area of ​​support provided by the elastic bladders 52.

[0096] In some embodiments, the support frame 51 includes a divider 53 that separates adjacent elastic bladders 52. The divider 53 can be used to create multiple placement zones within the support frame 51, with each elastic bladder 52 placed in a corresponding placement zone, facilitating the rapid, zoned placement of the elastic bladders 52. Furthermore, the divider 53 separates the elastic bladders 52, preventing adjacent bladders 52 from squeezing each other during expansion. This facilitates accurate measurement of the pressure generated by the fluid within each bladder 52 and facilitates precise control of the fluid charge within each bladder 52.

[0097] The partition 53 may include a partition plate, a partition rib, etc., which are arranged in the support frame 51 .

[0098] In some embodiments, reference Figure 5 The partition 53 includes a partition groove 53a recessed into the outer surface of the support frame 51. The partition groove 53a extends along the Y direction, which intersects the X direction. The Y direction is the width of the bottom guard plate 11. The partition groove 53a serves as a reinforcing rib to increase the rigidity of the support frame 51. Furthermore, by using the partition groove 53a recessed into the outer surface of the support frame 51 as the partition 53, the space occupied by the support frame 51 is not increased, which facilitates the layout of the support frame 51 and simplifies its processing.

[0099] In some embodiments, the cell pack 20 includes an explosion-proof valve located on the side of the cell pack 20 facing the cold plate 40 along the Z direction. The thermally conductive structural adhesive 30 clears the explosion-proof valve. The cold plate 40 is provided with a clearance portion 40a, and the flexible member 50 is provided with a thinned portion 54. The explosion-proof valve, the clearance portion 40a, and the thinned portion 54 are arranged correspondingly along the Z direction. The clearance portion 40a and the thinned portion 54 are configured to allow the flow of high-temperature, high-pressure flue gas released when the explosion-proof valve releases pressure. The fluid filled in cavity k includes a fire extinguishing agent, and the thinned portion 54 allows the high-temperature, high-pressure flue gas to enter cavity k for cooling by the fire extinguishing agent.

[0100] Specifically, multiple explosion-proof valves are provided at the bottom of each cell group 20, arranged side by side along the length or width of the bottom guard plate 11. A relief portion 40a is provided on the cold plate 40 corresponding to each explosion-proof valve, and a thinned portion 54 is provided on the flexible member 50 corresponding to each relief portion 40a.

[0101] In one embodiment, the cold plate 40 is a single piece that exchanges heat with all the battery cell groups 20, and the avoidance portion 40a is a avoidance hole provided on the cold plate 40. In another embodiment, the cold plate 40 is a plurality of pieces, and the intervals between adjacent cold plates 40 serve as the avoidance gaps of the avoidance portion 40a.

[0102] The thinned portion 54 may be a partially thinned portion of the flexible member 50 to form a scored structure. The scored structure may be in the shape of a cross, a straight line, a circle, a ring, a wave, etc. The thinned portion 54 may also be formed by machining a hole structure in the flexible member 50 and then providing a thin film structure with a relatively small thickness in the hole structure. The film structure serves as a seal.

[0103] The fire extinguishing substance in the cavity k may include hot aerosol, heptafluoropropane gas, hexafluoropropane, carbon dioxide, foam extinguishing agent, perfluorohexanone liquid, etc.

[0104] In actual application, when the explosion-proof valve releases pressure, high-temperature and high-pressure flue gas is ejected toward the cold plate 40, and after passing through the avoidance portion 40a, it breaks through the thinned portion 54 and releases the fire-extinguishing substance in the cavity k, thereby actively extinguishing the fire and cooling the room, preventing heat from spreading, and improving the safety of the battery pack 100.

[0105] Specifically, if the flexible member 50 includes the aforementioned support frame 51, the thinned portion 54 is disposed within the support frame 51. If the flexible member 50 only includes the aforementioned support frame 51, the fire extinguishing substance is directly filled within the cavity k formed by the support frame 51. When the thinned portion 54 is breached, the fire extinguishing substance within the cavity k is released, actively extinguishing the fire and reducing the temperature. If the flexible member 50 also includes an elastic bladder 52 within the support frame 51, the elastic bladder 52 forms the cavity k. When the thinned portion 54 is breached, the high-temperature, high-pressure flue gas acts on the elastic bladder 52, causing it to melt / break, releasing the fire extinguishing substance. For example, the elastic bladder 52 can be provided with a structure such as the aforementioned notch. Upon entering the support frame 51, the high-temperature, high-pressure flue gas breaks through the notch in the elastic bladder 52, causing it to break and release the fire extinguishing substance. Alternatively, the elastic bladder 52 can be made of a flexible polymer material with a relatively low melting point, such as PP, PE, TPU, etc., so that upon entering the support frame 51, the high-temperature, high-pressure flue gas melts the elastic bladder 52, causing it to release the fire extinguishing substance.

[0106] In some embodiments, combined Figure 2 and Figure 6 The side of the bottom guard plate 11 facing the cold plate 40 is recessed away from the cold plate 40 to form a receiving groove 11a. The flexible member 50 and the pipe G connected to the flexible member 50 are arranged within the receiving groove 11a. This allows the flexible member 50 and its pipe G to be accommodated in the existing battery pack 100 by simply modifying the bottom guard plate 11. This simplifies the production of the battery pack 100 and reduces the cost of modifying the battery pack 100.

[0107] Specifically in the embodiment, Figure 6 As shown, the filling piece 12 is arranged on the lateral peripheral wall of the bottom guard plate 11. It is possible that a plurality of filling pieces 12 are arranged on the lateral peripheral wall of the bottom guard plate 11. In this way, it is convenient for the pipeline G to be routed.

[0108] In some embodiments, reference Figure 8 The filling element 12 comprises a valve body 12e, a core 12a, an ejector pin 12b, and a sealing plug 12c. The valve body 12e has a through-hole e1, within which the core 12a, ejector pin 12b, and sealing plug 12c are all located. A core cavity a1 is defined within the core 12a, and ejector pin 12b extends through the core cavity a1 and is movable relative to the core 12a in the depth direction of the through-hole e1. The sealing plug 12c is fixed to the ejector pin 12b and can open and close the core cavity a1 as it moves with the ejector pin 12b.

[0109] Specifically, the bottom guard plate 11 is provided with a mounting hole, into which the valve body 12e is mounted, housing the core 12a, ejector pin 12b, and sealing plug 12c. The valve body 12e and bottom guard plate 11 can be secured by gluing, laser welding, cold pressing, or other methods. The core 12a is secured within the through-hole e1, while the ejector pin 12b extends through the core cavity a1 of the core 12a, with both ends extending beyond the cavity a1. One end is adapted to engage an external interface, while the other end is connected to the sealing plug 12c.

[0110] In practical application, combined with Figure 8 To illustrate, after the interface of the fluid supply device is docked with the left end of valve body 12e, the interface pushes ejector pin 12b along core cavity a1 toward the right end, connecting pipe G connected to the right end of valve body 12e with the fluid supply device. Fluid can enter and exit cavity k of flexible member 50 through through-hole e1. When the interface of the fluid supply device is removed from the left end of valve body 12e, the ejector pin moves leftward, driving sealing plug 12c to close core cavity a1.

[0111] At this time, the valve body 12e houses the ejector pin, core body 12a, and sealing plug 12c, thereby preventing external forces from accidentally contacting the conductive filling member 12 and improving the reliability of the filling member 12. Furthermore, the ejector pin drives the sealing plug 12c to open and close the core chamber a1 to connect and disconnect the filling member 12, which is simple in structure and easy to implement.

[0112] In some embodiments, the filling member 12 further includes an elastic member 12d, which is connected to the ejector pin 12b and provides the elastic force that allows the ejector pin 12b to drive the sealing plug 12c to close the core cavity a1. This allows the elastic member 12d to automatically return the ejector pin 12b to the position where the sealing plug 12c closes the core cavity a1 when the external interface is removed. This prevents leakage in the filling member 12, making it more reliable.

[0113] Regarding the arrangement of the elastic member 12d, in one embodiment, the elastic member 12d comprises a spring sheet disposed in the through hole e1, one end of the spring sheet being connected to the hole wall of the through hole e1, and the other end being connected to the ejector pin 12b. When the ejector pin 12b is squeezed by the external interface and moves to the right end, the spring sheet is stretched. When the external interface is withdrawn, the spring sheet is reset and pulls the ejector pin 12b back to its original position. In another embodiment, referring to Figure 8Core cavity a1 comprises a first cavity section a11 and a second cavity section a12, which are coaxially connected along the depth direction of through-hole e1. The inner diameter of first cavity section a11 is larger than that of second cavity section a12. First cavity section a11 is located on the side of second cavity section a12 facing away from sealing plug 12c. Elastic member 12d comprises a spring disposed within first cavity section a11. The spring is sleeved on ejector pin 12b. Ejector pin 12b includes a shoulder b1 located within first cavity section a11. First cavity section a11 has an inner wall spaced relative to shoulder b1 in the depth direction of through-hole e1. The spring is positioned within the space between the inner wall and shoulder b1. When ejector pin 12b is squeezed to the right by the external interface, the spring is compressed. When the external interface is removed, the spring returns ejector pin 12b to its original position.

[0114] In other embodiments, the elastic member 12d may not be provided, and the position restoration of the ejector pin 12b may be achieved by the external interface. In other embodiments, a spring may be provided on one side of the sealing plug 12c, and the spring may be used to push the sealing plug 12c to close the core chamber a1 and push the ejector pin to restore its position.

[0115] In some embodiments, the battery pack 100 further includes a monitoring device and a pressure detector. The pressure detector is used to determine the supporting force provided by the fluid in the cavity k on the cold plate 40. The monitoring device is in communication with the pressure detector and is used to determine whether the battery pack 100 is debonded based on the detection results obtained by the pressure detector.

[0116] The pressure sensing element can be a piezoelectric sensor, a piezoresistive sensor, or the like. Specifically, the pressure sensing element can be positioned at the end of the filling element 12 connected to the cavity k, within the pipeline G connected to the cavity k, or within the cavity k, or between the flexible member 50 and the cold plate 40. It is worth noting that the pressure P (in MPa) detected by the pressure sensing element refers to the force per unit area. The supporting force F provided by the flexible member 50 to the cold plate 40 can be determined by P*S, where S is the contact area between the flexible member 50 and the cold plate 40 and can be set to a default value.

[0117] The monitoring device can be a battery management system (BMS) or other processing device within the battery pack 100. Debonding of the battery pack 100 refers to the partial separation (or partial separation) of the thermally conductive adhesive 30 between the cold plate 40 and the battery cell assembly 20. This separation is likely to occur when the battery pack 100 is subjected to external force or other hazards, reducing the heat transfer efficiency and effectiveness between the cold plate 40 and the battery cell assembly 20. When the thermally conductive adhesive 30 separates, the pressure detected by the pressure detection element fluctuates. Upon detecting this fluctuation, the monitoring device determines that debonding has occurred in the battery pack 100.

[0118] In this way, the setting of the flexible member 50 can not only effectively support the cold plate 40 and balance the forces on the upper and lower parts, but also be used to detect whether the thermal conductive structural adhesive 30 is debonded, so as to timely discover abnormal conditions of the battery pack 100, thus achieving multiple uses.

[0119] Please refer to Figure 9 and Figure 10 The present application also provides a method for preparing a battery pack 100. The method includes:

[0120] S1. During the process of pressing the battery cell group 20 into the box body 10 using the pressing mechanism 200, the pressing force exerted by the pressing mechanism 200 on the cold plate 40 through the battery cell group 20 is monitored;

[0121] Specifically, the end plates 60 at both ends of the cell group 20 are clamped by a clamping mechanism to transport the cell group 20 into the housing 10, and the pressing mechanism 200 is used to press down on the cell group 20 to press the cell group 20 into the housing 10. In order to detect the downward force exerted by the pressing mechanism 200 on the cold plate 40, it is possible, but not limited to, to set a pressure sensor at the pressure application position of the pressing mechanism 200 on the cell group 20 to determine the downward force of the cold plate 40. When the pressing mechanism 200 has multiple pressure application positions on the cell group 20, the downward force is determined based on the sum of the pressures at each pressure application position. A pressure sensing structure can also be set at the pressing head of the pressing mechanism 200 to monitor the downward force provided by the pressing mechanism 200.

[0122] S2. According to the downward pressure, control the power pump connected to the filling member 12 to inject fluid into the cavity k until the fluid in the cavity k of the flexible member 50 provides a supporting force to the cold plate 40 that is equivalent to the downward pressure.

[0123] The fluid supply device is connected to the filling member 12 via a power pump. A pressure sensor can be installed at the power pump to obtain real-time fluid pressure, or alternatively, the pressure detection device mentioned above can be used to obtain real-time fluid pressure. A target fluid pressure is determined based on the downforce, and the timing of the power pump's injection of fluid into cavity k is controlled based on the difference between the real-time fluid pressure and the target fluid pressure. When the real-time fluid pressure reaches the target fluid pressure, indicating that the supporting force provided by the fluid on the cold plate 40 is equivalent to the downforce, the power pump is stopped.

[0124] At this time, during the assembly process of the battery pack 100, the power pump is controlled to input fluid into the cavity k according to the downward pressure exerted by the downward pressure mechanism 200 on the cold plate 40, so that the supporting force provided by the fluid is equivalent to the downward pressure, so that the cold plate 40 is subjected to balanced force up and down, and the cold plate 40 is not prone to local concavity. The thickness of the thermal conductive structural adhesive 30 filled between the cold plate 40 and the battery cell group 20 is uniform, the cold plate 40 and the battery cell group 20 can transfer heat evenly, and the thermal management effect of the battery pack 100 is better.

[0125] When a plurality of filling pieces 12 are provided on the battery pack 100 , the same power pump is independently connected to each filling piece 12 and can deliver fluid to each filling piece 12 synchronously.

[0126] Figure 11 Schematic diagram of a flow chart of a debonding detection method for a battery pack 100 according to some embodiments.

[0127] In addition, the present application also provides a debonding detection method for a battery pack 100, which is applied to the battery pack 100 in the above embodiment. The debonding detection method includes:

[0128] P1. Monitoring the fluctuation of the supporting force provided by the fluid in the cavity k of the flexible member 50 to the cold plate 40;

[0129] P2. When the fluctuation of the supporting force exceeds the allowable fluctuation range, it is determined that the battery pack 100 is debonded;

[0130] P3, output debonding reminder information.

[0131] Specifically, after the battery pack 100 is assembled and in use, the battery management system (BMS) uses the pressure sensor to determine the supporting force provided by the fluid within the flexible member 50. This supporting force F acting on the cold plate 40 can be calculated based on the force P detected by the pressure sensor. The calculated supporting force F can be compared with a pre-stored standard supporting force. If the difference exceeds the allowable range, this indicates that the battery pack 100 is debonding. If the difference remains within the allowable range, this indicates that the battery pack 100 is not debonding.

[0132] When it is determined that the battery pack 100 is debonded, the BMS can report debonding prompt information to the electrical device (such as a car or airplane) loaded with the battery pack 100, and provide timely warnings to improve the reliability of the electrical device.

[0133] The debonding detection method of the battery pack 100 determines whether the battery pack 100 is debonded based on the fluctuation of the supporting force provided by the fluid in the flexible member 50 to the cold plate 40. This method can timely detect abnormal conditions of the battery pack 100 and improve the reliability of the battery pack 100.

[0134] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A battery pack, characterized in that: include: The box body (10) includes a bottom guard plate (11); A battery cell group (20), a heat-conducting structural adhesive (30), and a cold plate (40) stacked in sequence along a Z direction, wherein the Z direction is a thickness direction of the bottom guard plate (11); and A flexible member (50) is provided on the bottom guard plate (11) and supported on a side of the cold plate (40) away from the heat-conducting structural adhesive (30); along the Z direction, the projection of the flexible member (50) overlaps with the projection of the battery cell group (20); a cavity (k) is constructed inside the flexible member (50), and a fluid is loaded in the cavity (k); the flexible member (50) is constructed to expand and contract with changes in the fluid content in the cavity (k) to adjust the supporting force of the flexible member (50) on the cold plate (40); and a filling member (12), the filling member (12) being in communication with the cavity (k) and capable of allowing the fluid to enter and exit the cavity (k) so as to control the content of the fluid in the flexible member (50); The flexible member (50) includes an elastically expandable support frame (51), and the cold plate (40) is supported by the support frame (51); the cavity (k) is located in the support frame (51), and the support frame (51) has an initial volume. When the fluid causes the volume of the cavity to exceed the initial volume, the support frame (51) is squeezed by the fluid and expands to increase its volume; The flexible member (50) further comprises an elastic sac (52) forming the cavity (k), wherein the elastic sac (52) is located in the support frame (51); the volume of the elastic sac (52) can change with the content of the fluid inside. When the fluid causes the volume of the elastic sac (52) to exceed the initial volume, the support frame (51) is squeezed by the elastic sac (52) and expands to increase its volume.

2. The battery pack according to claim 1, wherein: The flexible member (50) and the battery cell group (20) are both configured in plurality; in the Z direction, each battery cell group (20) is provided with a flexible member (50) in one-to-one correspondence; There are multiple filling pieces (12), and the cavity (k) of each flexible piece (50) is independently connected to a filling piece (12) via a pipeline (G).

3. The battery pack according to claim 1, wherein: A plurality of elastic bags (52) are provided in the support frame (51), and all the elastic bags (52) are sequentially spaced and arranged along the X direction, where the X direction is the length direction of the bottom guard plate (11); Each elastic bag (52) in the same support frame (51) is independently connected to the filling piece (12) via a pipeline (G).

4. The battery pack according to claim 3, wherein: The support frame (51) includes a partition (53), and the partition (53) is separated between adjacent elastic bags (52); The partition portion (53) comprises a partition groove (53a) recessed in the outer surface of the support frame (51), and the partition groove (53a) extends along a Y direction intersecting with the X direction, and the Y direction is the width direction of the bottom guard plate (11).

5. The battery pack according to claim 1, wherein: The flexible member (50) is at least arranged below the pressure action position of the battery cell group (20), and the pressure action position of the battery cell group (20) is used to be acted upon by the pressing mechanism (200) when the battery pack is assembled.

6. The battery pack according to claim 1, wherein: The battery cell group (20) includes an explosion-proof valve, the explosion-proof valve is located on a side of the battery cell group (20) facing the cold plate (40) along the Z direction, and the thermal conductive structural adhesive (30) avoids the explosion-proof valve; The cold plate (40) is provided with a relief portion (40a), the flexible member (50) is provided with a thinning portion (54), the explosion-proof valve, the relief portion (40a) and the thinning portion (54) are arranged correspondingly along the Z direction; the relief portion (40a) and the thinning portion (54) are configured to be able to flow high-temperature and high-pressure flue gas released when the explosion-proof valve is depressurized; The fluid filled in the cavity (k) includes a fire extinguishing substance, and the thinned portion (54) allows high-temperature and high-pressure smoke to enter the cavity (k) to be cooled by the fire extinguishing substance.

7. The battery pack according to claim 1, wherein: The filling member (12) comprises a valve body (12e), a core body (12a), a ejector pin (12b) and a sealing plug (12c); the valve body (12e) has a through hole (e1); the core body (12a), the ejector pin (12b) and the sealing plug (12c) are all arranged in the through hole (e1); A core cavity (a1) is provided in the core body (12a), and the ejector pin (12b) passes through the core cavity (a1) and is movable relative to the core body (12a) in the depth direction of the through hole (e1); The sealing plug (12c) is fixed to the ejector pin (12b) and can open and close the core cavity (a1) when moving with the ejector pin (12b).

8. The battery pack according to claim 1, wherein: The battery pack further comprises a monitoring device and a pressure detection member, wherein the pressure detection member is used to determine the supporting force provided by the fluid in the cavity (k) to the cold plate (40), and the monitoring device is communicatively connected with the pressure detection member and is used to determine whether the battery pack is debonded based on the detection result obtained by the pressure detection member.

9. A method for preparing a battery pack, applied to the battery pack according to any one of claims 1 to 8, characterized in that: The preparation method comprises: In the process of using a pressing mechanism (200) to press the battery cell group (20) into the box (10), detecting the downward pressure exerted by the pressing mechanism (200) on the cold plate (40) through the battery cell group (20); According to the downward pressure, a power pump connected to the filling member (12) is controlled to inject the fluid into the cavity (k) until the fluid in the cavity (k) of the flexible member (50) provides a supporting force to the cold plate (40) that is equivalent to the downward pressure.

10. A method for detecting debonding of a battery pack, applied to the battery pack according to any one of claims 1 to 8, characterized in that: The degumming detection method comprises: monitoring fluctuations in the supporting force provided by the fluid in the cavity (k) of the flexible member (50) to the cold plate (40); When the fluctuation of the supporting force exceeds the allowable fluctuation range, it is determined that the battery pack is debonded; Output degumming prompt information.

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