Battery cell protection device, battery pack and electric equipment

Abstract

The embodiment of the invention provides a battery cell protection device, a battery pack and electric equipment, the battery cell protection device comprises a first pressing plate, a second pressing plate and a first connecting structure, and the second pressing plate and the first pressing plate are oppositely arranged. The first connecting structure is connected with the first pressing plate and the second pressing plate, the first connecting structure comprises at least one rigid part, at least one first elastic part and at least one elastic assembly which are sequentially connected, and the elastic assembly comprises at least two second elastic parts which are connected in parallel; the stiffness coefficient of the first elastic piece is different from that of the elastic assembly. The battery cell protection device in the embodiment of the invention can effectively cope with the respiratory action of the battery pack and reduce thermal runaway to the greatest extent, ensure that the structure of the battery pack is stable, prolong the cycle life of the battery pack and improve the reliability and safety of the whole system.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell protection device, a battery pack, and an electrical device. Background Art

[0002] With the rapid development of the economy and technology, batteries are increasingly being used. Lithium-ion batteries, with their advantages of high packaging reliability, high system energy efficiency, high energy density, simple structure, long cycle life, and relatively good stability, have been widely used in various fields, playing an irreplaceable role in energy storage, mobile devices, and the automotive industry.

[0003] Batteries consist of cells, which can experience performance degradation and expansion over long periods of cycling. To minimize cell expansion and deformation, batteries typically include protective devices to limit the cell's position and protect it.

[0004] However, the above protection device is difficult to cope with the breathing effect of the battery and the expansion force generated by the thermal runaway effect. Summary of the Invention

[0005] The embodiments of the present application provide a battery cell protection device, a battery pack, and an electrical device to effectively cope with breathing and minimize thermal runaway, thereby ensuring the structural stability of the battery pack, extending the cycle life of the battery pack, and improving the reliability and safety of the entire system.

[0006] The present invention provides a battery protection device, comprising:

[0007] first pressing plate;

[0008] a second pressing plate, arranged opposite to the first pressing plate;

[0009] A first connecting structure connects the first pressure plate and the second pressure plate, the first connecting structure includes at least one rigid member, at least one first elastic member, and at least one elastic component connected in sequence, the elastic component includes at least two second elastic members connected in parallel, and the stiffness coefficient of the first elastic member is different from the stiffness coefficient of the elastic component.

[0010] In some possible implementations, there are multiple first connection structures, and the multiple first connection structures are connected to the surfaces of the first pressing plate and the second pressing plate facing each other, and are arranged at intervals along the edge of at least one side of the first pressing plate.

[0011] In some possible implementations, along the direction from the first pressing plate to the second pressing plate, the rigid members, the first elastic members, and the elastic components in the plurality of first connection structures are arranged in the same order.

[0012] In some possible implementations, one end of the rigid member in each of the first connection structures is connected to one of the first pressing plate and the second pressing plate, and one end of the elastic component is connected to the other of the first pressing plate and the second pressing plate.

[0013] In some possible embodiments, along the direction from the first pressure plate to the second pressure plate, the arrangement order of the rigid parts, the first elastic parts and the elastic components in part of the first connection structure is opposite to the arrangement order of the rigid parts, the first elastic parts and the elastic components in the rest of the first connection structure.

[0014] In some possible implementations, a stiffness coefficient of the first elastic member is greater than a stiffness coefficient of the second elastic member.

[0015] In some possible implementations, the first connection structure includes a rigid member, a first elastic member, and an elastic component, and the elastic component includes two second elastic members;

[0016] One end of the rigid member is connected to the first pressure plate, the other end of the rigid member is connected to one end of the first elastic member, the other end of the first elastic member is connected to one end of the two second elastic members, and the other ends of the two second elastic members are connected to the second pressure plate.

[0017] In some possible implementations, the first elastic member includes a first spring, a first end plate, and a first pull rod;

[0018] Both ends of the first spring are connected to the first end plates respectively, and one end of the first end plate away from the first spring is connected to the first pull rod.

[0019] In some possible implementations, the first elastic member further includes a first sleeve, and the first sleeve is sleeved outside the first spring.

[0020] In some possible implementations, the second elastic member includes a second spring, a second end plate, and a second pull rod;

[0021] Both ends of the second spring are respectively connected to the second end plate, and one end of the second end plate away from the second spring is connected to the second pull rod.

[0022] In some possible implementations, the second elastic member further includes a second sleeve, and the second sleeve is sleeved outside the second spring.

[0023] In some possible implementations, the second elastic member further includes a connecting plate provided on at least one side of the second spring, and the connecting plate is correspondingly connected to an end of the second pull rod away from the second spring.

[0024] In some possible implementations, the rigid member includes a first pull rod.

[0025] In some possible implementations, the battery cell protection device further includes a second connecting structure;

[0026] The second connecting structure connects the first pressing plate and the second pressing plate, and is located at two opposite ends of the first pressing plate with the first connecting structure.

[0027] In some possible implementations, the second connection structure is the same as the first connection structure;

[0028] Alternatively, the second connection structure includes a second pull rod.

[0029] An embodiment of the present application further provides a battery pack, comprising at least two battery cells, and the battery cell protection device as described above, which is arranged on the outside of the at least two battery cells.

[0030] In some possible implementations, an arrangement direction of the first pressing plate and the second pressing plate of the battery cell protection device is the same as an arrangement direction of the at least two battery cells.

[0031] An embodiment of the present application also provides an electrical device, including the battery pack as described above.

[0032] In the battery cell protection device, battery pack, and electrical equipment of the embodiments of the present application, a first pressure plate and a second pressure plate are arranged opposite each other; a first connecting structure connects the first and second pressure plates. The first connecting structure includes at least one rigid member, at least one first elastic member, and at least one elastic component connected in sequence. The elastic component includes at least two second elastic members connected in parallel, and the stiffness coefficient of the first elastic member is different from the stiffness coefficient of the elastic component. By providing at least one rigid member, the battery cell protection device and the battery cell can be prevented from falling apart. By adjusting the number, stiffness coefficient, and arrangement of the first and second elastic members, the overall stiffness of the battery cell protection device can be varied over a wide range, thereby obtaining a battery cell protection device that meets different constraint requirements based on actual needs and the stiffness variation pattern of the battery cell protection device. In this way, localized excessive force that may damage the battery cell can be avoided, thereby effectively addressing the breathing effect of the battery pack and minimizing thermal runaway, ensuring the structural stability of the battery pack, extending the cycle life of the battery pack, and improving the reliability and safety of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0034] Figure 1 A schematic diagram of a battery pack;

[0035] Figure 2 is a schematic diagram of a battery pack in an embodiment of the present application;

[0036] Figure 3 for Figure 2 A partial enlarged view of point A in the middle;

[0037] Figure 4 for Figure 2 A partial enlarged view of point B in the middle;

[0038] Figure 5 A side view of a battery pack in an embodiment of the present application;

[0039] Figure 6 Schematic diagram of the relationship between cell displacement and force in an embodiment of the present application.

[0040] Description of reference numerals:

[0041] 10-battery cell; 11-tab;

[0042] 20-pull strip;

[0043] 31-first pressing plate; 32-second pressing plate;

[0044] 40-first connecting structure; 41-rigid member; 42-first elastic member; 43-second elastic member;

[0045] 51-first spring; 52-first end plate; 53-first pull rod; 54-first sleeve;

[0046] 61 - second spring; 62 - second end plate; 63 - second pull rod; 64 - second sleeve; 65 - connecting plate. DETAILED DESCRIPTION

[0047] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0048] First, let’s explain the terms involved in this application:

[0049] Respiration: refers to the phenomenon that the charge and discharge process of the battery pack causes chemical reactions inside the battery pack, resulting in gas generation or material expansion.

[0050] Thermal runaway: This refers to a phenomenon in which both the current and temperature of a battery pack increase, and both increase and reinforce each other, while the battery pack is in use or charging. When thermal runaway occurs, the surge in heat inside the battery pack causes a rapid increase in temperature, which will trigger a more dramatic volume change.

[0051] There are two common restraint methods for protective devices. One is the restraint method without tie bars, that is, after multiple cells are compressed, only the pressure plate / side plate is used to fix the four sides of multiple cells. The other is the restraint method with tie bars, see Figure 1 That is, after the multiple battery cells 10 are compressed, multiple pull bars 20 are set on the top to strengthen the fixation and increase the stability of the restraint.

[0052] The former restraint method can easily cause multiple battery cells to shift, become dislocated, or even fall apart during transportation, failing to ensure smooth and safe transportation. The latter restraint method is difficult to control in terms of tightness. If the tie 20 restrains the battery cell 10 too tightly, it may cause some damage to the battery cell 10. If the tie 20 restrains the battery cell 10 too loosely, it cannot effectively prevent the battery cell 10 from shifting or dislocating during transportation.

[0053] The material properties and dimensions of the tie bars 20 used in the latter restraint method are fixed, and their rigidity is also unchangeable, making it difficult to cope with the expansion forces generated by the breathing and thermal runaway effects of the battery cells 10. This means that when the battery cells 10 breathe or even experience thermal runaway, the resulting increase in thickness and even rapid increases in temperature and pressure within the cells 10 will seriously affect the cycle life and safety performance of the battery pack.

[0054] To this end, an embodiment of the present application provides a battery cell protection device, which is provided with at least one first elastic member and at least one elastic component connected in series, and the elastic component includes at least two second elastic members connected in parallel, and the stiffness coefficient of the first elastic member is different from the stiffness coefficient of the elastic component. By adjusting the number, stiffness coefficient and arrangement of the first elastic member and the second elastic member, the overall stiffness of the battery cell protection device can be changed within a large range, so that according to actual needs and the stiffness change law of the battery cell protection device, a battery cell protection device that meets different restraint requirements can be obtained. In this way, it is possible to avoid damage to the battery cell due to excessive local force, thereby effectively coping with the breathing effect of the battery pack and minimizing thermal runaway, ensuring the structural stability of the battery pack, extending the cycle life of the battery pack, and improving the reliability and safety of the entire system.

[0055] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0056] Please refer to Figures 1 to 6 The present invention provides an electric device, which may be an electric vehicle, an electric train, an electric bicycle, a golf cart, a mobile phone, a portable device, a laptop computer, an electric toy, an electric tool, a ship, etc. The electric vehicle includes a pure electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle.

[0057] The above-mentioned electrical equipment includes a battery pack, which provides energy for the electrical equipment. The battery pack can be a lithium-ion battery pack. Figure 2 The battery pack may include at least two battery cells 10. The battery cells 10 may be rectangular in shape, i.e., blade-shaped battery cells. At least one of the two opposing sides of the battery cell 10 may be provided with a tab 11. For example, the two opposing sides of the battery cell 10 may be opposite sides of the battery cell 10 along the length direction.

[0058] Among them, at least two battery cells 10 are arranged in sequence along a first direction, and the first direction is the thickness direction of the battery cell 10. Figure 2 As shown in the X direction, the length direction of the battery cell 10 is as follows Figure 2 In this way, the large surfaces of two adjacent battery cells 10 face each other, which can reduce the space occupied by the battery cells 10 as a whole. The large surface refers to the surface with the largest area in the battery cell 10.

[0059] See Figures 2 to 5 The battery pack also includes a cell protection device, which is disposed outside at least two battery cells 10. That is, at least two battery cells 10 are placed inside the cell protection device, and the cell protection device is used to restrain and secure these battery cells 10. When these battery cells 10 experience temperature changes and increase in thickness during the charge and discharge process, the battery cells 10 will generate a certain expansion force on the cell protection device, and at the same time, the battery cells 10 will also be subject to the restraining force of the cell protection device on these battery cells 10.

[0060] The battery cell protection device includes a first pressure plate 31, a second pressure plate 32, and a first connecting structure 40. The second pressure plate 32 is arranged opposite the first pressure plate 31; the first connecting structure 40 connects the first and second pressure plates 31 and 32. The first connecting structure 40 includes at least one rigid member 41, at least one first elastic member 42, and at least one elastic assembly connected in sequence. The elastic assembly includes at least two second elastic members 43 connected in parallel. The spring coefficient of the first elastic member 42 is different from the spring coefficient of the elastic assembly.

[0061] This arrangement, by providing at least one rigid member 41, prevents the cell protection device and the cell 10 from falling apart. By adjusting the number, stiffness coefficient, and arrangement of the first and second elastic members 42, 43, the overall stiffness of the cell protection device can be varied over a wide range. This allows for cell protection devices that meet different restraint requirements based on actual needs and the stiffness variation patterns of the cell protection device. This prevents damage to the cell 10 due to localized excessive force, effectively counteracts the breathing effect of the battery pack, minimizes thermal runaway, ensures a stable battery pack structure, extends the cycle life of the battery pack, and improves the reliability and safety of the entire system.

[0062] It is understandable that the battery cell 10 generates an outward expansion force during the breathing or thermal runaway effect, the magnitude of which depends on the pressure inside the battery cell 10 of the battery pack and the rigidity of the battery cell protection device, as shown below:

[0063]

[0064] Among them, F K Indicates the expansion force of the battery pack due to breathing or thermal runaway effect, P I represents the pressure inside the battery cell 10, and A represents the force-bearing area of ​​the battery cell 10.

[0065] To prevent displacement or structural damage caused by expansion force, the cell guard provides an inward tightening force, the magnitude of which depends on the material, rigidity, and pre-tightening of the cell guard, as shown below:

[0066]

[0067] Among them, F R represents the clamping force of the cell protection device on the battery cell 10, k represents the stiffness of the cell protection device, and ΔL represents the elongation or deformation of the cell protection device.

[0068] When the expansion force of the battery cell 10 is greater than the tightening force of the battery cell protection device, the battery cell 10 will be displaced. The magnitude of the displacement depends on the difference between the two and the total stiffness of the battery cell protection device, as shown below:

[0069]

[0070]

[0071] Wherein, F represents the force on the battery cell 10 , X represents the displacement of the battery cell 10 , and K represents the total stiffness of the entire battery cell protection device.

[0072] In some possible examples, the arrangement direction of the first pressing plate 31 and the second pressing plate 32 of the battery cell protection device is the same as the arrangement direction of at least two battery cells 10. Figure 2 As shown, the first pressing plate 31 and the second pressing plate 32 are arranged opposite each other along the thickness direction of the battery cell 10 and are respectively located on the two outermost large surfaces of at least two battery cells 10. The first pressing plate 31 and the second pressing plate 32 can both be flat plates, which have a large contact area with the battery cell 10 and improve the overall uniformity of the force applied to the battery cell 10.

[0073] The edges of the first pressing plate 31 and the second pressing plate 32 may protrude from the battery cell 10 to facilitate connection with the first connection structure 40 and provide certain protection for the first connection structure 40. Exemplarily, both ends of the first pressing plate 31 and the second pressing plate 32 along the width direction of the battery cell 10 protrude from the corresponding ends of the battery cell 10, so that the first connection structure 40 is connected between the surfaces of the first pressing plate 31 and the second pressing plate 32 facing each other. In this way, at least part of the first connection structure 40 is located in the space between the first pressing plate 31 and the second pressing plate 32, reducing the exposure of the first connection structure 40. Figure 1 As shown in FIG. 2 , the first connection structure 40 is arranged on the opposite side of the battery cell 10 along the width direction. This can avoid interference between the first connection structure 40 and the tab 11 and facilitate external connection of the tab 11 .

[0074] Continue reading Figure 2 The first connecting structure 40 includes at least one rigid member 41, at least one first elastic member 42, and at least one elastic assembly. For example, the first connecting structure 40 includes one rigid member 41, one first elastic member 42, and one elastic assembly. Another example includes one rigid member 41, two first elastic members 42, and one elastic assembly. The rigid member 41, the first elastic member 42, and the elastic assembly form the components corresponding to the first connecting structure 40. These components are connected end-to-end in a certain order, i.e., the at least one rigid member 41, the at least one first elastic member 42, and the at least one elastic assembly are connected in series.

[0075] The order of connection between the components of the first connection structure 40 is not limited. For example, in a case where the first connection structure 40 includes a rigid member 41, two first elastic members 42, and an elastic assembly, in one connection method, the rigid member 41, the first elastic member 42, the elastic assembly, and the first elastic member 42 are connected in sequence. In another connection method, the first elastic member 42, the rigid member 41, the elastic assembly, and the first elastic member 42 are connected in sequence. In yet another connection method, the elastic assembly, the first elastic member 42, the rigid member 41, and the first elastic member 42 are connected in sequence.

[0076] Among them, the rigid member 41 may include a first pull rod, which has a simple structure and is easy to arrange. The elastic component includes at least two second elastic members 43 connected in parallel, that is, at least two second elastic members 43 are connected end to end and end to end, and at least two second elastic members 43 in an elastic component are connected in parallel. The stiffness coefficient of the first elastic member 42 is different from the stiffness coefficient of the elastic component, so that the stiffness of the first elastic member 42 is different from the stiffness of the elastic component. Changing the arrangement method and number can adjust the total stiffness of the first connection structure 40, and can achieve the purpose of multi-stiffness fitting and adjustable clamping force, thereby realizing variable stiffness restraint of at least two battery cells 10.

[0077] It is understood that the stiffness of the rigid member 41 is greater than that of the first elastic member 42 and greater than that of the elastic assembly. The stiffness of the rigid member 41 can be approximately infinite, while the stiffness of the first elastic member 42 is related to its spring constant. The stiffness of the elastic assembly is related to the spring constant and number of the second elastic members 43. The combination of different first and second elastic members 42, 43 can vary the overall stiffness of the first connecting structure 40. When multiple first elastic members 42 are connected in series, their stiffness decreases, while when multiple second elastic members 43 are connected in parallel, the stiffness of the elastic assembly increases.

[0078] When the first elastic member 42 and the second elastic member 43 both comprise springs, refer to the following formula:

[0079]

[0080]

[0081] Among them, K c represents the total stiffness of the springs in series, K p represents the total stiffness of the springs in parallel, k n represents the spring constant of the nth spring.

[0082] To improve the overall stability of the battery cell protection device and the restraining effect on the battery cell 10, in some possible embodiments, there are multiple first connection structures 40. The multiple first connection structures 40 are connected to the mutually facing surfaces of the first pressure plate 31 and the second pressure plate 32, and are arranged at intervals along the edge of at least one side of the first pressure plate 31. Exemplarily, multiple first connection structures 40 are arranged along the length of the battery cell 10 to ensure that the restraining force applied by the battery cell protection device to the battery cell 10 varies uniformly, helping to prevent deformation or damage to the battery cell 10 caused by local overpressure.

[0083] In some possible implementations, the multiple first connection structures 40 have the same specific structure, that is, the stiffness coefficient, number, and arrangement order of the rigid member 41, first elastic member 42, and second elastic member 43 in each first connection structure 40 are all the same. This ensures that the multiple first connection structures 40 are evenly stressed and can move synchronously, thereby improving the overall performance of the battery cell protection device.

[0084] In some possible examples, the multiple first connection structures 40 also have the same connection relationship with the first pressing plate 31 and the second pressing plate 32. That is, along the direction from the first pressing plate 31 to the second pressing plate 32, the arrangement order of the rigid members 41, the first elastic members 42, and the elastic components in the multiple first connection structures 40 is the same. This can further ensure the consistency of the deformation of the multiple first connection structures 40 and improve the uniformity of the overall force applied to the at least two battery cells 10.

[0085] In other possible examples, along the direction from the first pressure plate 31 to the second pressure plate 32, the arrangement order of the rigid members 41, the first elastic members 42, and the elastic components in some first connection structures 40 is opposite to the arrangement order of the rigid members 41, the first elastic members 42, and the elastic components in the remaining first connection structures 40, so as to make the first connection structures 40 structurally symmetrical. In this way, the multiple first connection structures 40 can be divided into two parts, and the arrangement order of the rigid members 41, the first elastic members 42, and the elastic components in each part of the first connection structures 40 is the same, and the arrangement order of the components in one part of the first connection structures 40 is opposite to the arrangement order of the components in the other part of the first connection structures 40.

[0086] It is understood that the two first connection structures 40 have the same structure, differing only in their connections to the first and second pressure plates 31, 32. Specifically, the components of all first connection structures 40 are arranged in the same order from beginning to end. Some first connection structures 40 have their beginnings connected to the first pressure plate 31 and their ends connected to the second pressure plate 32, while others have their beginnings connected to the second pressure plate 32 and their ends connected to the first pressure plate 31. For example, along the length of the battery cell 10, the two first connection structures 40 are arranged alternately.

[0087] Continue reading Figure 2 In some possible embodiments, one end of the rigid member 41 in each first connecting structure 40 is connected to one of the first pressing plate 31 and the second pressing plate 32, and one end of the elastic component is connected to the other of the first pressing plate 31 and the second pressing plate 32. Thus, the rigid member 41 disposed at one end of the first connecting structure 40 can improve the stability of the first connecting structure 40. The elastic component is disposed at the other end of the first connecting structure 40, and each second elastic member 43 in the elastic component can be connected to the first pressing plate 31 or the second pressing plate 32, thereby improving the stability of the connection between the elastic component and the first pressing plate 31 or the second pressing plate 32.

[0088] The stiffness coefficient of the first elastic member 42 is greater than that of the second elastic member 43, meaning that the first elastic member 42 is more susceptible to elastic deformation. Thus, the first elastic member 42 deforms first, allowing the entire first connection structure 40 to generate at least three levels of stiffness to cope with the displacement changes of the battery cell 10 in different states. The turning points of the different levels of stiffness include when the first elastic member 42 moves to its maximum limit state and when the elastic assembly moves to its maximum limit state.

[0089] In some possible implementations, such as Figure 2 As shown, one end of the rigid member 41 is connected to the first pressure plate 31, the other end of the rigid member 41 is connected to one end of the first elastic member 42, the other end of the first elastic member 42 is connected to one end of two second elastic members 43, and the other ends of the two second elastic members 43 are connected to the second pressure plate 32. In this way, the two second elastic members 43 are connected in parallel and then in series with the first elastic member 42 and the rigid member 41.

[0090] Among them, see Figure 3 and Figure 4 The first elastic member 42 includes a first spring 51, a first end plate 52, and a first pull rod 53. The first spring 51 is connected to the first end plate 52 at each end, and the first end plate 52, distal from the first spring 51, is connected to the first pull rod 53. The first spring 51 provides a certain degree of flexibility, allowing the battery cell 10 to expand under varying temperature conditions during the charge and discharge process, thereby reducing structural damage caused by thermal stress. The spring constant of the first spring 51 is the same as the spring constant of the first elastic member 42.

[0091] Exemplarily, both ends of the first spring 51 are fixedly connected to the first end plate 52, for example, by welding or forming an integral structure. The end surface of the first end plate 52 is connected to the first spring 51. The end surface of the first end plate 52 has a large area, which facilitates the connection between the first end plate 52 and the first spring 51. The first end plate 52 can be a flat plate, a circular plate, or an elliptical plate.

[0092] The first pull rod 53 is fixedly connected to the end of the first end plate 52 away from the first spring 51. For example, the first pull rod 53 is welded to the first end plate 52 or is an integral structure. The first pull rod 53 can be a straight rod. The first pull rod 53 is connected to another structure. For example, one end of the first pull rod 53 is welded to one end of the rigid member 41, and the other end of the first pull rod 53 is welded to the first end plate 52.

[0093] like Figure 3 and Figure 4 As shown, the first elastic member 42 also includes a first sleeve 54, which is sleeved outside the first spring 51. The first sleeve 54 can be cylindrical or elliptical, and is adapted to the first spring 51 to provide isolation, protection, and position limiting for the first spring 51. One end of the first sleeve 54 has an opening, and the other end is provided with a top plate, and the top plate has a through hole for the first pull rod 53 to pass through. The first spring 51 and at least one first end plate 52 are located in the first sleeve 54, and the opening of the first sleeve 54 is also fixedly connected to a first end plate 52 away from the top plate of the first sleeve 54, for example, by clamping or welding. In this way, when the first end plate 52 close to the top plate of the first sleeve 54 abuts against the top plate of the first sleeve 54, the first spring 51 moves to the maximum position, and the tightening force that the first spring 51 can provide reaches the maximum.

[0094] Continue reading Figure 3 and Figure 4 The second elastic member 43 includes a second spring 61, a second end plate 62, and a second pull rod 63. The second spring 61 is connected to the second end plate 62 at both ends, and the end of the second end plate 62, distal from the second spring 61, is connected to the second pull rod 63. The second spring 61 provides a certain degree of flexibility, allowing the battery cell 10 to expand under varying temperature conditions during the charge and discharge process, thereby reducing structural damage caused by thermal stress. The sum of the spring constants of the second springs 61 is the spring constant of the second elastic member 43.

[0095] Exemplarily, both ends of the second spring 61 are fixedly connected to the second end plate 62, for example, by welding or forming an integral structure. The end surface of the second end plate 62 is connected to the second spring 61. The end surface of the second end plate 62 has a large area, which facilitates the connection between the second end plate 62 and the second spring 61. The second end plate 62 can be a flat plate, a circular plate, or an elliptical plate.

[0096] The second pull rod 63 is fixedly connected to the end of the second end plate 62 away from the second spring 61. For example, the second pull rod 63 is welded to the second end plate 62 or is an integral structure. The second pull rod 63 can be a straight rod, and the second pull rod 63 is connected to another structure. For example, one end of the second pull rod 63 is welded to the second pressure plate 32, and the other end of the second pull rod 63 is welded to the second end plate 62.

[0097] like Figure 3 and Figure 4 As shown, the second elastic member 43 also includes a second sleeve 64, which is sleeved outside the second spring 61. The second sleeve 64 can be cylindrical or elliptical, and is adapted to the second spring 61 to provide isolation, protection, and positioning for the second spring 61. One end of the second sleeve 64 has an opening, and the other end is provided with a top plate, and the top plate has a through hole for the second pull rod 63 to pass through. The second spring 61 and at least one second end plate 62 are located in the second sleeve 64, and the opening of the second sleeve 64 is also fixedly connected to a second end plate 62 away from the top plate of the second sleeve 64, for example, by clamping or welding. In this way, when the second end plate 62 close to the top plate of the second sleeve 64 abuts against the top plate of the second sleeve 64, the second spring 61 moves to the maximum position, and the tightening force that the second spring 61 can provide reaches the maximum.

[0098] In order to facilitate the connection of the second elastic member 43, the second elastic member 43 also includes a connecting plate 65 arranged on at least one side of the second spring 61. The connecting plate 65 corresponds to the end of the second pull rod 63 away from the second spring 61. This can ensure that the second springs 61 are parallel, so that the deformation direction of the second springs 61 remains consistent, and the uniformity of the force applied to each second spring 61 can be improved.

[0099] Illustratively, along the direction from the first pressure plate 31 to the second pressure plate 32, the rigid member 41, the first pull rod 53, the first end plate 52, the first spring 51, the first end plate 52, the first pull rod 53, the connecting plate 65, the second pull rod 63, the second end plate 62, the second spring 61, the second end plate 62, and the second pull rod 63 are connected in sequence.

[0100] Specifically, a connecting plate 65 is provided on the side of the second spring 61 away from the second pressing plate 32, and one end of the rigid member 41 is connected to the first pressing plate 31 (see Figure 2 The other end of the rigid member 41 is connected to one end of a first pull rod 53, the other end of the first pull rod 53 is connected to one end surface of a first end plate 52, the other end surface of the first end plate 52 is connected to one end of a first spring 51. The other end of the first spring 51 is connected to one end surface of another first end plate 52, the other end surface of the first end plate 52 is connected to one end of another first pull rod 53, the other end of the first pull rod 53 is connected to one end surface of a connecting plate 65, the other end surface of the connecting plate 65 is connected to one end of a second pull rod 63, the other end of the second pull rod 63 is connected to one end surface of a second end plate 62, the other end surface of the second end plate 62 is connected to one end of a second spring 61, the other end of the second spring 61 is connected to one end surface of another second end plate 62, the other end surface of the second end plate 62 is connected to one end of another second pull rod 63, and the other end of the second pull rod 63 is connected to the second pressure plate 32.

[0101] In order to facilitate the explanation of the working principle of the battery protection device in the embodiment of the present application, the embodiment of the present application is described by taking the above-mentioned first connection structure 40 as an example, wherein the above-mentioned first connection structure 40 includes a rigid member 41, a first elastic member 42 and an elastic component, the elastic component includes two second elastic members 43, the first elastic member 42 includes a first spring 51, a first end plate 52, a first pull rod 53 and a first sleeve 54, and the second elastic member 43 includes a second spring 61, a second end plate 62, a second pull rod 63 and a second sleeve 64. The stiffness of the first spring 51, the second spring 61 and the rigid member 41 are k a 、k b and k c , where k a <k b .

[0102] The battery pack will breathe during the charging and discharging process, causing the battery cell 10 material to expand and contract, that is, the battery cell 10 will undergo a certain degree of displacement. At this time, the battery protection structure is subjected to the expansion force of the battery cell 10, and the first elastic member 42 and the elastic component will undergo elastic deformation. The first pull rod 53 is connected to the first end plate 52, driving the first spring 51 to move together, and the second pull rod 63 is connected to the second end plate 62, driving the second spring 61 to move together. When the temperature of the battery cell 10 continues to rise, the expansion force it generates increases, and the first end plate 52 will first contact the top plate of the first sleeve 54. The tightening force that the first spring 51 can provide reaches its maximum, and then the two second springs 61 move to the maximum tightening force.

[0103] In the above process, the top plates of the first sleeve 54 and the second sleeve 64 affect the stiffness of the cell protection device in three stages to cope with the displacement changes of the battery cell 10 in different states. The stiffness of the cell protection device in the three stages are as follows:

[0104]

[0105]

[0106]

[0107] Among them, 2k b Indicates that both stiffness coefficients are k b The total stiffness of the second spring 61 in parallel, k c It can be approximated to infinity.

[0108] The total stiffness K of the cell protection device includes three stages: k1, k2, and k3. The piecewise linear function relationship between the displacement of the cell 10 and its stress is shown as follows:

[0109]

[0110] Among them, S1, S2, and S3 correspond to slight, significant, and severe expansion states caused by the continuous increase in the temperature of the battery cell 10, respectively. The severe expansion state here refers to the situation where the battery cell 10 has a thermal runaway effect.

[0111] See Figure 6 , Figure 6 The figure shows the relationship between the displacement of the battery cell 10 and the force it is subjected to. The horizontal axis represents the force F of the battery cell 10, and the vertical axis represents the displacement X of the battery cell 10. S1, S2, and S3 correspond to the three expansion states shown in the above formula. The straight line R1, the broken line R2, and the curve R3 respectively represent the constant stiffness constraint state, the variable stiffness constraint state, and the ideal constraint state of the fitted broken line of the battery cell 10. Among them, the two turning points of the broken line R2 represent the maximum limit states of the first spring 51 and the second spring 61 moving to their respective top plates.

[0112] from Figure 6 It can be seen that when the displacement X of the battery cell 10 is constant, the force on the battery in the variable stiffness constraint state is much smaller than that in the constant stiffness constraint state. This indicates that the battery cell protection device in the embodiment of the present application can greatly reduce the deformation or damage to the battery cell 10 caused by excessive constraint. The multi-stiffness fitting of the first elastic member 42 and the second elastic member 43 can make the battery cell 10 subject to an ideal constraint force that is approximately evenly distributed.

[0113] In order to improve the stability of the battery cell protection device, in some possible embodiments, the battery cell protection device further includes a second connecting structure (not shown in the figure); the second connecting structure connects the first pressing plate 31 and the second pressing plate 32, and is located at opposite ends of the first pressing plate 31 to the first connecting structure 40.

[0114] For example, the first connection structure 40 and the second connection structure are arranged opposite to each other along the width direction of the battery cell 10. Figure 2 As shown, the first connection structure 40 is located at the top of the battery cell 10, and the second connection structure is located at the bottom of the battery cell 10, so that there is a connection between the opposite ends of the first pressure plate 31 and the corresponding ends of the second pressure plate 32, which can reduce the battery cell protection device and the battery cell 10 from falling apart.

[0115] Multiple second connection structures and first connection structures 40 may be provided, for example, with a one-to-one correspondence between each second connection structure and the first connection structure 40, with the corresponding second connection structures and first connection structures 40 facing each other along the width direction of the battery cell 10. The second connection structure is the same as the first connection structure 40; or the second connection structure includes a second brace.

[0116] Exemplarily, the second connection structure also includes at least one rigid member, at least one first elastic member, and at least one elastic assembly. The number, order, and connection relationship of these components, as well as their connection to the first and second pressure plates 31 and 32, are all identical. This improves the overall uniformity of the battery cell protection device and makes the force applied to the battery cell 10 more uniform. Furthermore, exemplary, the second connection structure includes a second tie rod, one end of which is connected to the first pressure plate 31 and the other end of which is connected to the second pressure plate 32. This simplifies the overall structure of the battery cell protection device.

[0117] The battery cell protection device in the embodiment of the present application includes a first pressure plate 31, a second pressure plate 32 and a first connecting structure 40. The second pressure plate 32 is arranged opposite to the first pressure plate 31; the first connecting structure 40 connects the first pressure plate 31 and the second pressure plate 32. The first connecting structure 40 includes at least one rigid member 41, at least one first elastic member 42, and at least one elastic component connected in sequence. The elastic component includes at least two second elastic members 43 connected in parallel. The stiffness coefficient of the first elastic member 42 is different from the stiffness coefficient of the elastic component. By providing at least one rigid member 41, the battery cell protection device and the battery cell 10 can be prevented from falling apart. By adjusting the number, stiffness coefficient and arrangement of the first elastic member 42 and the second elastic member 43, the overall stiffness of the battery cell protection device can be changed within a large range. Therefore, according to actual needs and the stiffness change law of the battery cell protection device, a battery cell protection device that meets different constraint requirements can be obtained. In this way, damage to the battery cell 10 due to excessive local force can be avoided, thereby effectively coping with the breathing effect of the battery pack and minimizing thermal runaway, ensuring the structural stability of the battery pack, extending the cycle life of the battery pack, and improving the reliability and safety of the entire system.

[0118] In this specification, each embodiment or implementation method is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referenced to each other. The descriptions with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0119] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell protection device, characterized in that: include: a first pressing plate (31); a second pressing plate (32), arranged opposite to the first pressing plate (31); A first connecting structure (40) connects the first pressure plate (31) and the second pressure plate (32), wherein the first connecting structure (40) includes at least one rigid member (41), at least one first elastic member (42), and at least one elastic component connected in sequence, wherein the elastic component includes at least two second elastic members (43) connected in parallel, and the stiffness coefficient of the first elastic member (42) is different from the stiffness coefficient of the elastic component.

2. The battery cell protection device according to claim 1, characterized in that: There are a plurality of the first connecting structures (40), and the plurality of the first connecting structures (40) are connected to the surfaces of the first pressing plate (31) and the second pressing plate (32) facing each other, and are arranged at intervals along the edge of at least one side of the first pressing plate (31).

3. The battery cell protection device according to claim 2, characterized in that: Along the direction from the first pressing plate (31) to the second pressing plate (32), the rigid members (41), the first elastic members (42), and the elastic components in the plurality of first connection structures (40) are arranged in the same order.

4. The battery cell protection device according to claim 3, characterized in that: One end of the rigid member (41) in each of the first connection structures (40) is connected to one of the first pressure plate (31) and the second pressure plate (32), and one end of the elastic component is connected to the other of the first pressure plate (31) and the second pressure plate (32).

5. The battery cell protection device according to claim 2, characterized in that: Along the direction from the first pressure plate (31) to the second pressure plate (32), the arrangement order of the rigid member (41), the first elastic member (42) and the elastic component in part of the first connection structure (40) is opposite to the arrangement order of the rigid member (41), the first elastic member (42) and the elastic component in the rest of the first connection structure (40).

6. The battery cell protection device according to claim 1, characterized in that: The stiffness coefficient of the first elastic member (42) is greater than the stiffness coefficient of the second elastic member (43).

7. The battery cell protection device according to any one of claims 1 to 6, characterized in that: The first connecting structure (40) comprises a rigid member (41), a first elastic member (42) and an elastic component, wherein the elastic component comprises two second elastic members (43); One end of the rigid member (41) is connected to the first pressure plate (31), the other end of the rigid member (41) is connected to one end of the first elastic member (42), the other end of the first elastic member (42) is connected to one end of two second elastic members (43), and the other ends of the two second elastic members (43) are connected to the second pressure plate (32).

8. The battery cell protection device according to any one of claims 1 to 6, characterized in that: The first elastic member (42) comprises a first spring (51), a first end plate (52) and a first pull rod (53); Both ends of the first spring (51) are connected to the first end plates (52), respectively; and one end of the first end plate (52) away from the first spring (51) is connected to the first pull rod (53).

9. The battery cell protection device according to claim 8, characterized in that: The first elastic member (42) further includes a first sleeve (54), and the first sleeve (54) is sleeved outside the first spring (51).

10. The battery cell protection device according to any one of claims 1 to 6, characterized in that: The second elastic member (43) comprises a second spring (61), a second end plate (62) and a second pull rod (63); Both ends of the second spring (61) are respectively connected to the second end plate (62), and one end of the second end plate (62) away from the second spring (61) is connected to the second pull rod (63).

11. The battery cell protection device according to claim 10, characterized in that: The second elastic member (43) further includes a second sleeve (64), and the second sleeve (64) is sleeved outside the second spring (61).

12. The battery cell protection device according to claim 10, characterized in that: The second elastic member (43) further includes a connecting plate (65) provided on at least one side of the second spring (61), and the connecting plate (65) is correspondingly connected to an end of the second pull rod (63) away from the second spring (61).

13. The battery cell protection device according to any one of claims 1 to 6, characterized in that: The rigid member (41) includes a first pull bar.

14. The battery cell protection device according to any one of claims 1 to 6, characterized in that: The battery cell protection device further includes a second connecting structure; The second connection structure connects the first pressing plate (31) and the second pressing plate (32), and is located at opposite ends of the first pressing plate (31) to the first connection structure (40).

15. The battery cell protection device according to claim 14, characterized in that: The second connection structure is the same as the first connection structure (40); Alternatively, the second connection structure includes a second pull rod.

16. A battery pack, characterized in that: Comprising at least two battery cells (10), and a battery cell protection device according to any one of claims 1 to 14, arranged outside the at least two battery cells (10).

17. The battery pack according to claim 16, wherein: The arrangement direction of the first pressing plate (31) and the second pressing plate (32) of the battery cell protection device is the same as the arrangement direction of the at least two battery cells (10).

18. An electrical device, characterized in that: Including the battery pack according to claim 16 or 17.

Images