cell

Abstract

The application relates to the technical field of battery cell manufacturing, and provides a battery cell, which comprises a shell and a bottom supporting plate; a containing space for installing an electrode assembly is formed in the shell, a pressure relief hole is arranged on the bottom wall of the shell; the bottom supporting plate is arranged between the bottom wall and the electrode assembly and used for supporting the electrode assembly; a plurality of convex parts are arranged on the surface of the bottom supporting plate facing the bottom wall, the plurality of convex parts are supported on the inner surface of the bottom wall, an exhaust passage is formed between the bottom supporting plate and the bottom wall, and the exhaust passage is communicated with the pressure relief hole. The exhaust passage is formed between the bottom supporting plate and the inner side surface of the bottom wall of the shell through the arrangement of the convex parts, so that the rapid discharge of gas can be realized when thermal runaway occurs, and the electrode assembly is prevented from blocking the pressure relief hole.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery cell manufacturing, and in particular to a battery cell. BACKGROUND

[0002] In order to improve the safety performance of the battery monomer, a pressure relief mechanism is usually arranged on the battery monomer. When gas is generated inside the battery monomer due to abnormal operation, the gas can be discharged through the pressure relief structure to prevent a major safety accident.

[0003] In order to improve the capacity of the battery cell and the safety of the battery pack as much as possible, it is a very effective method to adjust the pressure relief structure from the cover plate to the side wall of the shell to achieve thermal and electrical separation.

[0004] In the related art, the pressure relief valve is usually arranged at the bottom of the battery shell, away from the electrical connection structure on the cover plate, to achieve effective thermal and electrical separation. However, when the battery cell experiences thermal runaway, due to the self-gravity of the electrode assembly, it will sink to the bottom of the shell and may cover the pressure relief hole, thereby causing the pressure relief hole to be blocked. At this time, the gas in the shell cannot be quickly discharged through the pressure relief valve, causing the internal gas pressure to be too large, increasing the risk of explosion. Therefore, there is an urgent need for a battery cell that can ensure the unobstructedness of the pressure relief hole during thermal runaway. SUMMARY

[0005] The present application provides a battery cell to solve the defect that the electrode assembly easily sinks and blocks the pressure relief hole during thermal runaway in the prior art.

[0006] The present application provides a battery cell, comprising: a shell and a bottom support plate; the shell forms a containing space for mounting an electrode assembly inside, and a pressure relief hole is arranged on the bottom wall of the shell; the bottom support plate is arranged between the bottom wall and the electrode assembly to support the electrode assembly; wherein a plurality of protrusions are arranged on the surface of the bottom support plate facing the bottom wall, the plurality of protrusions are supported on the inner surface of the bottom wall, so that an exhaust passage is formed between the bottom support plate and the bottom wall; and the exhaust passage communicates with the pressure relief hole.

[0007] According to the battery cell provided by the present application, the melting point Tm of the bottom support plate is greater than or equal to 250 DEG C.

[0008] According to the battery cell provided by the present application, a plurality of grooves are arranged near the two sides of the width direction of the bottom support plate, the groove bottom of the groove is protruded to the side away from the electrode assembly, and the protrusion is formed.

[0009] According to the battery cell provided by the present application, a through hole is arranged in each groove.

[0010] According to the battery cell provided by the present application, the groove edge of the groove and the groove bottom edge of the groove are both formed with a circular arc chamfer.

[0011] According to the electric cell provided by the application, the number of the grooves on both sides of the bottom plate in the width direction is the same, and the grooves are arranged in parallel and spaced one by one.

[0012] According to the electric cell provided by the application, the pressure relief hole is located in the gap region between the adjacent grooves in the width direction of the bottom plate.

[0013] According to the electric cell provided by the application, a fillet structure is formed at the connection between the bottom wall and the inner side wall of the shell.

[0014] According to the electric cell provided by the application, the radius of the fillet structure is r, the thickness of the bottom plate is a, and the protruding height b of the protruding part satisfies: 0.2mm≤b≤r-a.

[0015] According to the electric cell provided by the application, the radius of the fillet structure is 1.0mm≤r≤2.5mm, and the thickness of the bottom plate is 0.1mm≤a≤0.3mm.

[0016] According to the electric cell provided by the application, the protruding part is arranged to form an exhaust passage between the bottom plate and the inner surface of the bottom wall of the shell, so that the rapid discharge of gas can be realized in the thermal runaway, and the electrode assembly is prevented from blocking the pressure relief hole. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] Figure 1 is the overall structure of the electric cell provided by the application.

[0019] Figure 2 is the internal structure of the electric cell provided by the application.

[0020] Figure 3 is the three-dimensional structure of the electric cell provided by the application.

[0021] Figure 4 is the overall structure of the bottom plate of the electric cell provided by the application.

[0022] Figure 5 is the structure of the assembly relationship between the bottom plate and the shell of the electric cell provided by the application.

[0023] Reference signs:

[0024] 10, housing; 101, accommodating space; 102, bottom wall; 103, pressure relief hole; 104, round corner structure; 20, cover plate assembly; 30, insulation film; 40, bottom support plate; 401, protruding part; 402, sink; 403, through hole; 404, exhaust passage; 50, explosion-proof valve. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below with reference to the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0026] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of clarifying the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0028] In the embodiments of the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0029] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present specification, the illustrative description 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 appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0030] In the related art, in order to prevent the thermal runaway of the battery cell from causing a greater safety hazard, the pressure relief hole of the battery cell is arranged at the bottom of the shell, and a pressure relief valve is arranged in the pressure relief hole, so that the pressure relief position is away from the pole position on the cover plate, thereby improving the safety performance. However, this way will block the pressure relief hole on the shell when the battery cell is in thermal runaway, so that the gas in the shell cannot be discharged, and the safety risk is intensified.

[0031] In view of the problems in the related art, the following will be combined Figures 1-3 The battery cell provided by the present application includes a shell 10 and a bottom support plate 40. The shell 10 forms a containing space 101 for mounting an electrode assembly. The bottom wall 102 of the shell 10 is provided with a pressure relief hole 103. The bottom support plate 40 is arranged between the bottom wall 102 and the electrode assembly to support the electrode assembly. The surface of the bottom support plate 40 facing the bottom wall 102 is provided with a plurality of protruding portions 401. The plurality of protruding portions 401 are supported on the inner surface of the bottom wall 102, so that an exhaust passage 404 is formed between the bottom support plate 40 and the bottom wall 102. The exhaust passage 404 communicates with the pressure relief hole 103. When the battery cell is in thermal runaway, effective support is needed to prevent the electrode assembly from sinking and blocking the pressure relief hole 103 on the battery cell shell 10 under the action of gravity. In the present embodiment, the protruding portions 401 are arranged to effectively support the electrode assembly and form the exhaust passage 404, so that the rapid discharge of gas is realized, the stability of the entire electrode assembly support is improved, and the safety of the battery cell is improved.

[0032] Specifically, the battery cell shell 10 has a circumferential side wall and a bottom wall 102 to form a containing space 101. A cover plate assembly 20 is arranged at the top of the shell 10. The electrode assembly is arranged in the containing space 101 to realize overall assembly. The bottom support plate 40 is located between the electrode assembly and the bottom wall 102 of the shell 10, and is used to support the electrode assembly.

[0033] The protruding portion 401 is integrally formed with the bottom support plate 40, and can increase the distance between the bottom support plate 40 and the bottom wall 102 of the shell 10, so as to form a gap space between the main plate of the bottom support plate 40 and the bottom wall 102 of the shell 10. The gap space forms an exhaust passage 404, which communicates the internal space of the shell 10 and the pressure relief hole 103, so as to realize the rapid discharge of the gas in the shell 10 in the case of thermal runaway.

[0034] In a specific arrangement, the electrode assembly includes the pole group pole piece and the insulation film 30, and the insulation film 30 is used to wrap the pole group pole piece. In a specific connection, the bottom support plate 40 is arranged below the insulation film 30. In the case of thermal runaway, the insulation film 30 will quickly melt and release high-temperature and high-pressure gas. At this time, the high-temperature and high-pressure gas can quickly flow through the exhaust passage 404 and be quickly discharged from the position of the pressure relief hole 103, thereby improving the safety performance of the battery cell.

[0035] It can be understood that the internal space of the shell 10 is a closed space after the cover plate assembly 20 is connected. Once the battery cell has thermal runaway, the pressure in the shell 10 will quickly increase. Generally, a pressure relief member is arranged in the pressure relief hole 103. The pressure relief member can be opened to realize the communication between the inside and the outside environment and release the internal pressure when the internal pressure reaches a set value. In the embodiment, the distance between the bottom support plate 40 and the inner side surface of the bottom wall 102 of the shell 10 can be increased by the protruding portion 401, so as to form the exhaust passage 404. The high-pressure gas in the inside can be discharged in time, thereby improving the safety performance of the battery cell in the case of thermal runaway.

[0036] In combination with the above embodiment, the melting point Tm of the bottom support plate 40 is greater than or equal to 250°C. In the initial stage of thermal runaway of the battery cell, especially when the internal temperature is less than 250°C, the internal gas is rapidly produced and the gas production is huge. In the embodiment, the melting point of the bottom support plate 40 is limited to be greater than 250°C, so that the bottom support plate 40 can effectively support the electrode assembly at this temperature range, thereby maintaining the exhaust passage 404 unobstructed and realizing the rapid discharge of the high-pressure gas in the inside.

[0037] Specifically, the melting point of the bottom support plate 40 is higher than the melting point of the insulation film 30. In the case of thermal runaway, the insulation film 30 quickly melts, and the gas in the shell 10 can be quickly discharged through the exhaust passage 404, thereby realizing pressure relief and improving the safety performance of the battery cell.

[0038] It can be understood that the pole pieces in the shell 10 are generally composed of positive and negative materials, and the insulating film 30 separates them to prevent short circuit and ensure the safety and stability of the battery. Specifically, the insulating film 30 wraps the positive and negative materials to isolate them. The cell bottom plate 40 in the embodiment is arranged below the insulating film 30, and the protruding part 401 is in contact with the inner side surface of the bottom wall 102 of the shell 10 to support the electrode assembly, and an exhaust passage 404 is formed between the bottom wall 102 of the shell 10 and the main body of the bottom plate 40, which realizes the timely discharge of the internal high-pressure gas.

[0039] In some embodiments, as shown in Figure 4 A plurality of grooves 402 are arranged near the width direction of the bottom plate 40, and the groove bottom of the groove 402 protrudes away from the electrode assembly to form the protruding part 401. Through the arrangement of the groove 402, the overall mass of the bottom plate 40 can be lighter, which can facilitate the lightweight design of the overall battery cell and improve the safety performance of the battery cell.

[0040] Specifically, a plurality of grooves 402 are formed on the bottom plate 40 by stamping, and the groove body on the side facing the bottom wall 102 protrudes, thereby achieving effective support. This method can avoid the arrangement of additional materials, make the overall bottom plate 40 lightweight, and facilitate mass production through stamping forming, thereby reducing the difficulty of preparation.

[0041] In combination with the above embodiment, a through hole 403 is arranged in each groove 402. Through the arrangement of the through hole 403, the preparation difficulty of the protruding part 401 can be further reduced, and the exhaust rate can be strengthened during thermal runaway, thereby further improving the safety performance of the battery cell.

[0042] It can be understood that the bottom plate 40 is in the form of a plate body, and the groove 402 is positioned by the through hole 403 during processing, which can facilitate the processing and forming of the groove 402, improve the processing precision, and reduce the processing difficulty. During the production of the battery cell, the electrode assembly may jump, and the internal gas can be directly discharged through the through hole 403, thereby achieving rapid discharge of the gas. Further, during thermal runaway, the overall structure may also jump, and at this time the through hole 403 can be in communication with the exhaust passage 404, thereby facilitating the rapid discharge of the internal high-pressure gas.

[0043] In combination with the above embodiment, the groove edge of the groove 402 and the groove bottom edge of the groove 402 are formed with a circular arc chamfer. The circular arc chamfer can improve the stability of the overall structure.

[0044] Specifically, the upper surface of the bottom plate 40 is in contact with the insulating film 30 of the electrode assembly, and in this embodiment, the circular arc chamfer structure is arranged at the edge of the groove, which can avoid damage to the insulating film 30 and improve the stability of the structure.

[0045] Further, the circular arc chamfer structure at the edge of the groove bottom can facilitate the stamping forming of the sink groove 402 and ensure that the edge position has no corner and sharp structure, thereby improving the stability of the structure after assembly.

[0046] In some embodiments, the number of sink grooves 402 on both sides of the bottom plate 40 in the width direction is the same, and they are arranged one by one and spaced side by side. The bottom plate 40 needs to effectively support the electrode assembly and needs to ensure the stability of the support. In this embodiment, the sink grooves 402 are distributed on both sides of the bottom plate 40 in the width direction, which can make each protruding part 401 bear force evenly and improve the stability of the support of the bottom plate 40.

[0047] Specifically, the number of sink grooves 402 arranged in the width direction of the bottom plate 40 is the same, and the sink grooves 402 on each side are uniformly spaced along the length direction of the bottom plate 40. This makes the sink grooves 402 occupy a large area of the entire bottom plate 40, thereby achieving effective support and making the support more stable.

[0048] As shown in the above embodiments, as shown in Figure 2 , Figure 3 The pressure relief hole 103 is located in the gap region between the adjacent sink grooves 402 in the width direction of the bottom plate 40. When the battery cell is in thermal runaway, the internal gas pressure needs to be discharged quickly. In this embodiment, the pressure relief hole 103 is arranged between the adjacent sink grooves 402 in the width direction, which can facilitate the rapid discharge of internal gas.

[0049] Specifically, the sink grooves 402 in the width direction of the bottom plate 40 have a certain spacing, which is used to form an exhaust passage 404, and the exhaust passage 404 is directly communicated with the pressure relief hole 103, which makes the high-pressure gas in the internal directly enter the pressure relief hole 103 along the exhaust passage 404 and then be discharged.

[0050] It can be understood that the pressure relief hole 103 is provided with an explosion-proof valve 50, and the explosion-proof valve 50 is used to open when the pressure in the battery cell housing 10 reaches a predetermined threshold, so that the high-pressure gas in the internal can be discharged; in this embodiment, the pressure relief hole 103 is arranged in the exhaust passage 404, which can respond in time when the battery cell is in thermal runaway and can make the high-pressure gas in the internal quickly discharged along the pressure relief hole 103.

[0051] In some embodiments, a rounded structure 104 is formed at the junction between the bottom wall 102 and the inner side wall of the shell 10. When the battery cell experiences thermal runaway, a large amount of high-temperature gas and spatter is generated from the bottom electrode assembly and needs to be quickly discharged to the pressure relief hole 103 through the exhaust passage 404 below the bottom support plate 40. A right-angle structure (90° turn) can form a turbulent vortex area and a flow dead zone, significantly increasing the flow resistance. In the present embodiment, the design of the rounded structure 104 can facilitate the rapid discharge of internal gas.

[0052] Specifically, the rounded structure 104 can also improve the yield during processing. A right-angle stretch can easily cause the material to thin out or crack, and the rounded design allows the material to flow uniformly, improving the pass rate of stamping forming.

[0053] Further, since the rounded structure 104 is arranged to interfere with the electrode assembly and press the electrode assembly, the present embodiment can raise the electrode assembly by arranging the bottom support plate 40, thereby avoiding interference between the electrode assembly and the rounded structure 104 of the bottom wall 102 and improving the stability of the arrangement of the electrode assembly.

[0054] In combination with the above embodiments, as shown in Figure 5 , the radius of the rounded structure 104 is r, the thickness of the bottom support plate 40 is a, and the protruding height b of the protruding portion 401 satisfies: 0.2mm≤b≤r-a. The bottom support plate 40 is used to support the entire electrode assembly in the shell 10 and can be used to form the exhaust passage 404. In the present embodiment, the protruding height of the protruding portion 401 is limited so that the exhaust passage 404 has sufficient space to discharge high-temperature and high-pressure gas.

[0055] Specifically, the radius of the rounded structure 104 is greater than the thickness of the bottom support plate 40, and the limitation of b≥0.2mm ensures the minimum effective exhaust cross-sectional area of the exhaust passage 404, realizing effective exhaust of the exhaust passage 404. The limitation of b≤r-a ensures that a safety gap is reserved between the top of the protrusion and the rounded area of the shell 10, avoiding interference between the electrode assembly and the rounded structure 104.

[0056] In combination with the above embodiments, as shown in Figure 5 , the radius of the rounded structure 104 is 1.0mm≤r≤2.5mm, and the thickness of the bottom support plate 40 is 0.1mm≤a≤0.3mm. The radius of the rounded structure 104 needs to be kept within a reasonable range, and too large or too small a rounded radius will affect the formation of the shell 10 as a whole. Similarly, the thickness of the bottom support plate 40 needs to be kept within a reasonable range, and a too thin bottom support plate 40 will be difficult to effectively support, and a too thick bottom support plate 40 will occupy too much space inside the shell 10, which is not conducive to the utilization of the internal space of the shell 10.

[0057] In specific embodiments, the radius r of the rounded structure 104 is 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.3 mm or 2.5 mm. The thickness a of the bottom support plate 40 is 0.1 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm or 0.3 mm.

[0058] The above-mentioned value ranges are tested by specific examples as follows, and the test structure is shown in Table 1.

[0059] Table 1

[0060]

[0061] It can be known from the above test table that the thickness of the bottom support plate 40 needs to be limited in the range of 0.1 mm≤a≤0.3 mm, and exceeding the range will affect the overall support or overall space layout of the electrode assembly. The height of the raised portion 401 needs to satisfy 0.2 mm≤b≤r-a, and when the height of the raised portion 401 does not fall within the range, it will affect the function of the exhaust passage 404 or will occupy the space inside the shell 10.

[0062] Through the description of the above embodiments, those skilled in the art can clearly understand that in each embodiment, the exhaust passage 404 is formed between the bottom support plate 40 and the inner side surface of the bottom wall 102 of the shell 10 by the arrangement of the raised portion 401 on the bottom support plate 40, so that the rapid discharge of gas can be realized during thermal runaway, and the electrode assembly is prevented from blocking the pressure relief hole 103. Further, by limiting the height of the raised portion 401, the exhaust passage 404 can be ensured to be smooth, and the space layout can be more reasonable.

[0063] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, characterized in that, include: The housing has an accommodating space for mounting electrode assemblies, and a pressure relief hole is provided on the bottom wall of the housing. A base plate is disposed between the bottom wall and the electrode assembly to support the electrode assembly, and the melting point Tm of the base plate is ≥250℃; The base plate has multiple protrusions on its surface facing the bottom wall, and multiple grooves on both sides near the width direction of the base plate. The bottom of the grooves protrudes away from the electrode assembly to form the protrusions. The multiple protrusions are supported on the inner surface of the bottom wall, so that an exhaust channel is formed between the base plate and the bottom wall. Furthermore, the exhaust passage is connected to the pressure relief hole; The connection between the bottom wall and the inner side wall of the shell has a rounded corner structure with a radius of r. The thickness of the bottom support plate is a. The protrusion height b of the protrusion satisfies: 0.2mm≤b≤ra; the radius of the rounded corner structure is 1.0mm≤r≤2.5mm, and the thickness of the bottom support plate is 0.1mm≤a≤0.3mm.

2. The battery cell according to claim 1, characterized in that, The edges of the trough opening and the bottom edge of the trough are both rounded.

3. The battery cell according to claim 1, characterized in that, The number of sinkholes located on both sides of the width direction of the bottom support plate is the same, and they are arranged side by side with intervals.

4. The battery cell according to claim 1, characterized in that, The pressure relief hole is located in the gap area between adjacent sinkers in the width direction of the bottom support plate.

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