Battery cell, power battery pack and vehicle

Abstract

According to the battery cell, the power battery pack and the vehicle, a boss on the bottom wall in the battery cell is directly formed by inwards protruding a shell, the structure is simple, the overall weight of the battery cell can be reduced, and the lightweight design requirement of the whole vehicle is met. Even if the battery cell is in thermal runaway and the battery cell body is supported on the boss protruding out of the main body part, the anti-explosion valve is arranged on the main body part, a fluid channel is still formed between the battery cell body and the main body part, and a high-temperature fluid medium can flow in the fluid channel formed between the battery cell body and the main body part and is sprayed out from the anti-explosion valve, so that timely pressure relief in the battery cell is realized; in addition, the size of the fluid channel can be reasonably set by controlling the height of the boss, so that the potential safety hazard caused by thermal runaway of the battery cell is further reduced.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a battery cell, a power battery pack, and a vehicle. Background Technology

[0002] Currently, battery cells are equipped with explosion-proof valves. When thermal runaway occurs inside the cell, the high-temperature material inside can break through the explosion-proof valve and be ejected to the outside of the cell, thus providing pressure relief protection. Typically, a battery cell consists of a casing, the bare cell, and a top cover, with the bare cell located inside the casing. The location of the explosion-proof valve on the cell can be broadly categorized into two situations: the valve is located on the top cover or on the bottom wall of the casing. When the explosion-proof valve is located on the bottom wall of the casing, since the bare cell is also supported on the bottom wall, the gap between the bare cell and the bottom wall is relatively small. This limits the ejection of high-temperature material during thermal runaway to some extent, resulting in low ejection efficiency. The inability of the high-temperature material to be ejected from the casing in time may cause the cell to explode, potentially leading to an explosion of the power battery pack, posing a certain safety hazard.

[0003] Therefore, minimizing safety hazards during thermal runaway of battery cells is an important issue of concern to those skilled in the art. Utility Model Content

[0004] The purpose of this application is to provide a battery cell in which, in the event of thermal runaway, the high-temperature material inside the cell can be smoothly ejected from the explosion-proof valve, thereby improving the safety of the battery cell. Another purpose of this application is to provide a power battery pack and a vehicle including the above-mentioned battery cell.

[0005] This application provides a battery cell, including a casing, a battery cell body, an explosion-proof valve, a tab, and a terminal post. The casing has an inner cavity, and the battery cell body is located in the inner cavity. The casing includes a bottom wall, a side wall, and a top wall. The terminal post is located on the side wall or the top wall, and the explosion-proof valve is located on the bottom wall. The bottom wall includes a main body portion and a boss. The boss is connected to the main body portion and protrudes towards one side of the inner cavity. The explosion-proof valve is disposed on the main body portion.

[0006] In this embodiment, the boss is formed directly by the inward protrusion of the shell, resulting in a simple structure that helps reduce the overall weight of the battery cell and meets the lightweight design requirements of the vehicle. Even in the event of thermal runaway of the battery cell, the battery cell body is supported by the boss protruding from the main body. Because the explosion-proof valve is located in the main body, a fluid channel is still formed between the battery cell body and the main body. The high-temperature fluid medium can flow within the fluid channel formed between the battery cell body and the main body and be ejected from the explosion-proof valve, achieving timely pressure relief inside the battery cell and improving the safety of battery cell use. Furthermore, by controlling the height of the boss, the size of the fluid channel can be reasonably set, further reducing the safety hazards in the event of thermal runaway of the battery cell.

[0007] Furthermore, embodiments of this application also provide a power battery pack, including a battery box and at least one of the above-mentioned battery cells, wherein the battery cell is located inside the battery box.

[0008] This application also provides a vehicle, including a vehicle body and the aforementioned power battery pack, wherein the power battery pack is mounted on the vehicle body.

[0009] The power battery pack and vehicle of this application include the aforementioned battery cells, and therefore the power battery pack and vehicle also have the aforementioned technical effects of the battery cells. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a partial structure of the power battery pack in one embodiment of this application;

[0011] Figure 2 This is an exploded view of a battery cell in one embodiment of this application;

[0012] Figure 3 for Figure 2 A schematic diagram of the casing in the battery cell along the S-axis.

[0013] Figure 4 for Figure 3 A schematic diagram of the shell as viewed from the opening side;

[0014] Figure 5 This is a cross-sectional view of a battery cell in one embodiment of this application;

[0015] Figure 6 This is a cross-sectional view of the battery cell in the second embodiment of this application;

[0016] Figure 7 This is a cross-sectional view of the battery cell in the third embodiment of this application.

[0017] in, Figures 1 to 7 The one-to-one correspondence between the reference numerals and component names in the attached drawings is as follows:

[0018] 100 Battery cell; 1 Housing; 1A Inner cavity; 10 Explosion-proof valve; 11 Bottom wall; 111 Main body; 112 Boss; 113 Groove; 12 First side wall; 13 Second side wall; 2 Battery cell body; 3 Tab; 4 Top cover; 5 Insulating plate; 6 Pole post; 7 Insulating film; 8 Bracket. Detailed Implementation

[0019] This application uses the example of upright mounting of each battery cell, i.e., the terminal of each cell being located at the top of the cell, to introduce the technical solution and its effects. Of course, it is not excluded that the technical solution provided in this application can be applied to battery cells with side mounting or flip-flop mounting.

[0020] Please refer to Figures 1 to 7 , Figure 1This is a schematic diagram of a partial structure of the power battery pack in one embodiment of this application; Figure 2 This is an exploded view of a battery cell in one embodiment of this application; Figure 3 for Figure 2 A schematic diagram of the casing in the battery cell along the S-axis. Figure 4 for Figure 3 A schematic diagram of the shell as viewed from the opening side; Figure 5 This is a cross-sectional view of a battery cell in one embodiment of this application; Figure 6 This is a cross-sectional view of the battery cell in the second embodiment of this application; Figure 7 This is a cross-sectional view of the battery cell in the third embodiment of this application.

[0021] This application provides a power battery pack, which includes a housing 200 and a plurality of battery cells 100 located inside the housing 200. The battery cells 100 are stacked along a first direction X to form a cell group. The number of battery cells 100 in a cell group is typically several, such as two or more. The specific number of battery cells 100 depends on the specific product. Of course, it is not excluded that in some embodiments, a cell group may include only one battery cell 100. The first direction X is the direction in which the battery cells 100 are stacked in the cell group. The housing 200 may have one cell group inside, or it may have at least two cell groups arranged along a second direction Y. Figure 1 The diagram shows only one row of battery cells inside the housing 200. Those skilled in the art should understand that the number of battery cells inside the housing 200 is not limited to the number shown in the diagram. Although the specific structure of the aforementioned power battery pack is not shown, it does not impede the understanding of those skilled in the art regarding the above description.

[0022] The power battery pack also has a flexible circuit board 300 inside, which is used to transmit operating condition signals such as the temperature of the battery cell 100 to the external management system.

[0023] In this embodiment, the battery cell 100 includes components such as a casing and a battery cell body 2. The battery cell body 2 is also referred to as a bare battery cell or electrode roll. The battery cell body 2 includes stacked positive electrode sheets, negative electrode sheets, and separators, wherein the separator is located between adjacent positive and negative electrode sheets. The battery cell body 2 can be a wound battery cell or a stacked battery cell. In a wound battery cell, adjacent positive and negative electrode sheets and the separator are an integral structure, while in a stacked battery cell, adjacent positive and / or negative electrode sheets are separate structures. The positive electrode sheet includes a positive electrode active material, which can be any one or a combination of lithium iron phosphate, lithium nickel cobalt manganese oxide, or lithium manganese iron phosphate. The negative electrode sheet includes a negative electrode active material, which can be any one or a combination of artificial graphite, natural graphite, hard carbon, soft carbon, or silicon-based materials.

[0024] Typically, the housing includes a shell 1 and a top cover 4. The shell 1 has an inner cavity 1A, and the battery cell body 2 is located inside the inner cavity 1A. One side of the inner cavity 1A has an opening, and the top cover 4 is installed in the opening. The top cover 4 can seal the opening by sealing it with the shell 1. The top cover 4 is part of the top wall of the housing. An insulating plate 5 can also be provided between the top cover 4 and the battery cell body 2 to improve insulation protection. The shell 1 can be made of metal or non-metal.

[0025] In this embodiment, the battery cell body 2 is used to store electrical energy. The battery cell body 2 typically has two tabs 3, namely a positive tab and a negative tab. The battery cell also has two terminals 6, namely a positive terminal and a negative terminal. The positive terminal is electrically connected to the positive tab. Typically, the positive tab can be made of aluminum (Al) material, and the negative tab can be made of nickel (Ni) material. The negative tab can also be made of copper plated with nickel (Ni-Cu) material. Of course, the positive tab and the negative tab 3 can also be made of other materials, which will not be listed one by one in this article.

[0026] The negative terminal is electrically connected to the negative tab. The electrical connection between terminal 6 and tab 3 can be fixed by welding. Terminal 6 and tab 3 can be directly welded together, or they can be fixed by welding through an intermediate component, such as a connecting plate. The portion of terminal 6 located outside the housing 1 is electrically connected to the busbar 400. The terminals 6 of all cells 100 inside the housing 200 can be connected in series or / and in parallel through the busbar 400 according to a set rule to form a power supply. In this application, a cell group includes at least one row of busbars 400 arranged along a first direction. Typically, a cell group includes two rows of busbars 400. Figure 2 The example shown is that both pole posts 6 are located on one side of the top cover 4. Of course, the pole posts 6 can also be located on the bottom wall 11 or the side wall of the outer casing.

[0027] Among them, the positive terminal 6, negative terminal 6 and bus 400 can be made of single-component materials, such as copper or aluminum, which have good conductivity, or composite materials with different components, such as copper or aluminum, which have good conductivity, as long as they can achieve good conductivity.

[0028] Typically, to improve the safety of the battery cell 100, it is also equipped with an explosion-proof valve 10. The explosion-proof valve 10 is used to open in the event of thermal runaway of the battery cell 100, so as to discharge the internal pressure and thermal runaway substances from the inside of the battery cell 100's housing 1 to the outside of the housing. The explosion-proof valve 10 can be a welded explosion-proof plate on the through hole of the housing 1, or it can be a weak point on the surface of the housing 1. Please refer to... Figure 2 and Figure 3 Understood, in this embodiment, the explosion-proof valve 10 is located on the bottom wall 11. Figure 2The diagram shows a schematic of the explosion-proof valve 10 having an elongated oval structure. In this embodiment, the battery cell 100 has a cuboid structure, and correspondingly, the outer casing has four side walls, which are opposite each other in pairs. In this embodiment, the two side walls are defined as the first side wall 12 and the second side wall 13, respectively. The two first side walls 12 are opposite each other, and the two second side walls 13 are opposite each other. The first side wall 12 is the large surface of the battery cell, and the second side wall 13 is the small surface of the battery cell. The top cover 4 forms the top wall of the outer casing, and the bottom wall 11 of the casing 1 is the bottom wall of the outer casing. The two first side walls 12 and the two second side walls 13 enclose and form an annular cylinder, with the bottom wall 11 and the top wall located at the two ends of the annular cylinder.

[0029] The shape and specific structure of the explosion-proof valve 10 are not described in detail here; please refer to current technology. When the internal pressure of the housing 1 exceeds a predetermined pressure threshold, the high-temperature fluid medium inside the housing 1 will be ejected from the explosion-proof valve 10, ensuring the safety of the battery cell.

[0030] In this embodiment, the bottom wall 11 includes a main body 111 and a boss 112. The boss 112 is connected to the main body 111 and protrudes towards the inner cavity. The explosion-proof valve 10 is disposed on the main body 111. The main body 111 can be planar, and the boss 112 forms a groove 113 on the side away from the inner cavity 1A. The number of bosses 112 can be one or more, such as two, three, or four, with the bosses 112 arranged at intervals.

[0031] In this embodiment, the boss 112 is directly formed from the housing 1. For example, the housing 1 can be formed by stamping, stretching, or other processes. The cell body 2 can be supported on the boss 112 only in the event of thermal runaway. Of course, when the battery is in normal use, the cell body 2 can also be directly or indirectly supported on the boss 112, that is, the cell body 2 is always supported on the boss 112.

[0032] In this embodiment, the boss 112 is formed by the inward protrusion of the housing 1, which is simple in structure and helps to reduce the overall weight of the battery cell, meeting the requirements of lightweight vehicle design. Even if the battery cell experiences thermal runaway, the battery cell body 2 is supported by the boss 112 protruding from the main body 111. Because the explosion-proof valve 10 is located in the main body 111, a fluid channel is still formed between the battery cell body 2 and the main body 111. The high-temperature fluid medium can flow in the fluid channel formed between the battery cell body 2 and the main body 111 and be ejected from the explosion-proof valve 10, realizing timely pressure relief inside the battery cell, improving the safety of battery cell use. Furthermore, by controlling the height of the boss 112, the size of the fluid channel can be reasonably set, further reducing the safety hazards when the battery cell 100 experiences thermal runaway.

[0033] In this embodiment, there can be two bosses 112, which are arranged at intervals along the first direction. The two bosses 112 are located on both sides of the explosion-proof valve 10, that is, the explosion-proof valve 10 is located between the two bosses 112. The explosion-proof valve 10 can be located at the center of the bottom wall 11, and the two bosses 112 can be symmetrically arranged relative to the explosion-proof valve 10. This provides a more balanced support force on the battery cell body 2, which is beneficial for the stable installation of the battery cell body 2.

[0034] Please see Figure 6 In one example, the battery cell 100 further includes an insulating film 7, which wraps around the outside of the battery cell body 2. At least a portion of the tab 3 extends to the side of the insulating film 7 away from the battery cell body 2 to connect to the terminal post 6. The area of ​​the surface of the boss 112 facing the battery cell body 2 ranges from 200 mm² to 10000 mm², for example, 200 mm², 250 mm², 300 mm², 400 mm², 500 mm², 600 mm², 700 mm², 800 mm², 900 mm², or 1000 mm². Of course, the area of ​​the surface of the boss 112 facing the battery cell body 2 is not limited to the values ​​listed above and can be any value between 200 mm² and 10000 mm². In this way, the battery cell body 2 can be supported by the boss 112 by the insulating film 7, avoiding direct contact between the electrode of the battery cell body 2 and the housing 1, preventing electrode wear, and protecting the electrode. In addition, the insulating film 7 can achieve relative isolation between the battery cell body 2 and the boss 112, preventing short circuits in the battery cell body 2. At the same time, the insulating film 7 can protect the battery cell body 2 from physical damage during storage, transportation and assembly.

[0035] The insulating film 7 can be made of plastic material and can be fixed to the battery cell body 2 structure through a hot-melt process.

[0036] Please see Figure 7 In one specific embodiment, the battery cell further includes a bracket 8 located between the battery cell body 2 and the boss 112. A clearance channel is provided at the position of the bracket 8 opposite to the explosion-proof valve 10 to ensure that the high-temperature medium can flow smoothly through the clearance channel 81 to the explosion-proof valve 10. In this embodiment, the bracket 8 can be made of insulating material and can provide stable support for the battery cell body 2, forming the necessary venting channel between the battery cell body 2 and the side wall to facilitate rapid gas discharge and improve battery safety.

[0037] In addition, the large contact area between the bracket 8 and the cell body 2 is also conducive to the rapid dissipation of heat generated by the cell body 2 during normal operation.

[0038] In one specific example, the terminal 6 is located on the top wall. Under normal conditions, the cell body 2 is suspended on the top wall via the tab 3 and the terminal 6. There is a gap between the cell body 2 and the boss 112, so that the cell body 2 and the boss 112 are in a non-contact state to avoid wear on the cell body 2. The so-called normal state refers to the state in which the cell works normally, that is, the state in which thermal runaway does not occur.

[0039] In this embodiment, there is also a gap between the battery cell body 2 and the circumferential sidewall. During thermal runaway, the high-temperature fluid can flow along the gap between the battery cell body 2 and the sidewall to the gap between the battery cell body 2 and the bottom wall 11, and then be ejected from the explosion-proof valve 10 to the outside of the housing 1. That is, the circumferential gap between the battery cell body 2 and the sidewall is connected to the gap between the battery cell body 2 and the main body 111 of the bottom wall 11. Theoretically, the smaller the size of the boss 112, the more likely the high-temperature fluid medium can flow from the circumferential gap to the space between the battery cell body 2 and the main body 111.

[0040] In addition, the battery cell body 2 generates a large amount of heat during normal operation, which needs to be dissipated in a timely manner. The outer side of the bottom wall 11 of the battery cell is typically equipped with heat dissipation components, such as a liquid cooling plate or heat dissipation layer. The heat from the battery cell body 2 can be transferred to the external heat dissipation components through the protrusion 112 in contact with it. Theoretically, the larger the contact area between the protrusion 112 and the battery cell body 2, the higher the heat conduction capacity. This application proposes a specific design for the protrusion 112 that can balance the smooth flow of the high-temperature medium during thermal runaway and the rapid heat dissipation of the battery cell body 2 during normal operation.

[0041] In one example, the height A of the boss 112 ranges from 0.1mm to 2mm, such as 0.1mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, or 2mm. Similarly, the value of A is not limited to the values ​​listed above and can be any value between 0.1mm and 2mm. The higher the boss 112, the larger the space between the cell body 2 and the bottom wall 11, making it easier for fluid to flow out in the event of thermal runaway. The ratio B of the projected area of ​​the boss 112 to the area of ​​the bottom wall 11 ranges from 0.1 to 0.8, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, or 0.8. Again, the value of B is not limited to the values ​​listed above and can be any value between 0.1 and 0.8. The larger the value of B, the larger the area of ​​the bottom wall 11 occupied by the boss 112, the better the support stability of the battery cell body 2, and the more conducive it is to heat exchange of the battery cell body 2. When A is between 0.1mm and 2mm and B is between 0.1 and 0.8, the boss 112 can take into account the support stability of the battery cell body 2, high thermal conductivity, and rapid flow of thermal runaway fluid out of the shell 1.

[0042] Furthermore, when 1≤A / B≤2.5, the overall performance of the battery cell is better.

[0043] In one embodiment, the distance between the boss 112 and the side of the bottom wall 11 ranges from 5mm to 30mm, for example, 5mm, 10mm, 15mm, 20mm, 25mm, or 30mm. Similarly, the distance between the boss 112 and the side of the bottom wall 11 is not limited to the above values ​​and can be any value between 5mm and 30mm. This prevents the boss 112 from being too close to the side of the bottom wall 11, which could lead to excessive stress concentration and affect the strength of the battery bottom wall 11.

[0044] In this embodiment, the distance between the boss 112 and the explosion-proof valve 10 ranges from 5mm to 20mm, for example, 5mm, 8mm, 10mm, 12mm, 15mm, 18mm, or 20mm. Similarly, the distance between the boss 112 and the explosion-proof valve 10 can be from 5mm to 20mm and is not limited to the above values. This can reduce the influence of the boss 112 on the explosion-proof valve 10 and avoid inaccurate valve opening pressure caused by the boss 112.

[0045] The power battery pack provided in this application embodiment can be applied to a vehicle, which includes a vehicle body, and the power battery pack is installed in the vehicle body. Of course, the power battery pack can also be applied to other power consumption environments.

[0046] For other structural details regarding the vehicle and battery pack, please refer to current technology; this application will not elaborate further.

[0047] The vehicle described in this application includes the aforementioned power battery pack, and therefore the vehicle also possesses the aforementioned technical effects of the power battery pack.

[0048] In the description of embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0049] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0050] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A battery cell, characterized in that, The device includes a housing, a battery cell body (2), an explosion-proof valve (10), a tab (3), and a pole (6). The housing has an inner cavity (1A), and the battery cell body (2) is located in the inner cavity (1A). The housing includes a bottom wall (11), a side wall, and a top wall. The pole (6) is located in the side wall or the top wall. The explosion-proof valve (10) is located in the bottom wall (11). The bottom wall (11) includes a main body (111) and a boss (112). The boss (112) is connected to the main body (111) and protrudes toward the inner cavity (1A). The explosion-proof valve (10) is disposed in the main body (111).

2. The battery cell according to claim 1, characterized in that, The number of the bosses (112) is two, and the two bosses (112) are arranged at intervals along a first direction. The two bosses (112) are located on both sides of the explosion-proof valve (10), and the first direction is the length direction of the bottom wall (11).

3. The battery cell according to claim 1, characterized in that, The height of the boss (112) is A, and the ratio of the projected area of ​​the boss (112) on the bottom wall (11) to the area of ​​the bottom wall (11) is B, where 1≤A / B≤2.

5.

4. The battery cell according to claim 3, characterized in that, The height A of the boss (112) ranges from 0.1mm to 2mm; the ratio B of the projected area of ​​the boss (112) on the bottom wall (11) to the area of ​​the bottom wall (11) ranges from 0.1 to 0.

8.

5. The battery cell according to claim 1, characterized in that, The distance between the boss (112) and the side of the bottom wall (11) is in the range of 5 mm to 30 mm; Alternatively / and, the distance between the boss (112) and the explosion-proof valve (10) is in the range of 5mm~20mm.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The battery cell also includes an insulating film that wraps around the outside of the battery cell body (2). At least a portion of the tab (3) extends to the side of the insulating film away from the battery cell body (2) to connect the pole (6). The area of ​​the surface of the boss (112) facing the battery cell body (2) is in the range of 200 mm² to 10000 mm².

7. The battery cell according to any one of claims 1 to 5, characterized in that, The battery cell also includes a bracket, which is located between the battery cell body (2) and the boss (112). The bracket is provided with a clearance passage at the position opposite to the explosion-proof valve (10).

8. The battery cell according to any one of claims 1 to 5, characterized in that, The electrode post (6) is located on the top wall. Under normal conditions, the cell body (2) is suspended on the top wall through the tab (3) and the electrode post (6). There is a gap between the cell body (2) and the boss (112).

9. A power battery pack, characterized in that, It includes a battery box and at least one battery cell as described in any one of claims 1 to 8, the battery cell being located inside the battery box.

10. A vehicle, characterized in that, It includes a vehicle body and the power battery pack as described in claim 9, wherein the power battery pack is mounted on the vehicle body.

Images