Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, in particular to a battery cell and a battery pack. The battery cell comprises: a housing; the pole group is arranged in the shell; the insulating part is coated on the pole group; the cover plate assembly comprises a first cover plate, a second cover plate, a pole and a pressure relief part, the pole is arranged on the first cover plate, the pressure relief part is arranged on the second cover plate, the first cover plate and the second cover plate are installed on the shell, and only the insulating part is arranged between the second cover plate and the pole group. According to the invention, the risk of arcing fire at the pole position when the battery cell is subjected to thermal runaway can be reduced, and the safety performance of the battery cell is improved. In addition, compared with a traditional battery cell, the battery cell structure has the advantages that the occupied space of an end plate and lower plastic on one side is omitted, so that the effective space in the battery cell is increased, and the capacity of the battery cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cell and a battery pack. Background Art

[0002] As lithium-ion battery technology becomes increasingly mature, lithium-ion batteries are widely used as power batteries in electric vehicles and energy storage fields, and the requirements for the performance and safety of lithium-ion batteries are increasing.

[0003] Long cell lithium ion battery Figure 1 As shown, the pole ears extend from both sides of the electrode assembly 4, and the positive cover plate 1 and the negative cover plate 2 are respectively installed on the shell 8. After the positive cover plate 1 and the negative cover plate 2 are welded to the shell 8, a closed space that protects the electrode assembly 4 and has a certain mechanical strength is formed; a positive pole is arranged on the positive cover plate 1, and a negative pole is arranged on the negative cover plate 2. The electrode assembly 4 is laser-welded and fixed to the positive pole and the negative pole through the pole ears on both sides to achieve electrical connection; a lower plastic 3 is arranged on the side of the positive cover plate 1 and the negative cover plate 2 facing the electrode assembly 4, and a bare cell insulating film 6 wraps the electrode assembly 4 and is respectively fixed to the lower plastic 3 and the end plate 5 by hot melting, thereby ensuring that the electrode assembly 4 is isolated and insulated from the shell 8; an explosion-proof valve 7 structure is integrated on the positive cover plate 1 or the negative cover plate 2, which is mainly used for the directional discharge of internal high-temperature and high-pressure gas when thermal runaway occurs due to an internal short circuit, thereby improving the safety performance of the battery.

[0004] Since the positive and negative electrodes are set on different sides, both positive and negative electrodes need to be designed with a 5 to 9 mm thick lower plastic to provide bending space for the positive and negative electrode tabs. Figure 1 The cell assembly process is as follows: welding the pole ear to the negative electrode cover plate 2, installing the end plate 5, wrapping the bare cell insulation film 6, placing the electrode assembly 4 into the shell 8, welding and sealing the negative electrode cover plate 2 and the shell 8, welding the other pole ear to the positive electrode cover plate 1, and sealing and welding the positive electrode cover plate 1 and the shell 8; in order to fix the bare cell insulation film 6, the end plate 5 is added, which causes the length of the pole ear on this side to increase synchronously, and the required bending space is higher, which greatly reduces the occupied space of the electrode assembly 4 inside the cell, and the cell capacity is low; at the same time, the explosion-proof valve 5 must be set on the same side as the positive electrode column or the negative electrode column. When the cell thermal runaway occurs, accompanied by high-temperature and high-pressure gas gathering and erupting toward the explosion-proof valve position, the adjacent positive electrode column or negative electrode column will arc and catch fire due to the influence of temperature, which greatly aggravates the severity of the thermal runaway of the cell. Summary of the invention

[0005] In view of this, the purpose of the present application is to provide a battery cell and a battery pack to solve the problems that the existing battery cells have low capacity, the explosion-proof valve is close to the pole, the pole is affected by stability and arcing and fire will occur, which aggravates the severity of thermal runaway of the battery cell and affects the safety of the battery cell.

[0006] A first aspect of the present invention provides a battery cell, wherein the battery cell comprises:

[0007] case;

[0008] A pole group is arranged in the shell;

[0009] An insulating member, covering the pole group;

[0010] The cover plate assembly includes a first cover plate, a second cover plate, a pole and a pressure relief member, wherein the pole is arranged on the first cover plate, the pressure relief member is arranged on the second cover plate, the first cover plate and the second cover plate are installed on the shell, and only the insulating member is arranged between the second cover plate and the pole group.

[0011] Preferably, the cover plate assembly further comprises:

[0012] The plastic component is arranged on a side of the first cover plate facing the inside of the battery core, and the insulating component is connected to the plastic component by thermal melting.

[0013] Preferably, the electrode group is provided with protruding electrode ears, and the electrode ears include a positive electrode ear and a negative electrode ear, and the positive electrode ear and the negative electrode ear are arranged on the same side of the electrode group.

[0014] Preferably, a folded pole ear space is provided between the pole column and the pole group, and a dimension of the folded pole ear space in a thickness direction of the first cover plate is 6 mm to 8 mm.

[0015] Preferably, the poles include a positive pole and a negative pole, and the positive pole and the negative pole are spaced apart on the first cover plate.

[0016] Preferably, the first cover plate and the second cover plate are respectively connected to the shell by welding; after the second cover plate is welded to the shell, the first cover plate is welded to the shell.

[0017] Preferably, the first cover plate and the second cover plate are arranged parallel to each other.

[0018] Preferably, the first cover plate and the second cover plate are arranged opposite to each other at two ends in the length direction of the shell.

[0019] Preferably, a liquid injection hole is provided on the first cover plate, an exhaust hole is provided on the second cover plate, and the pressure relief member is installed at the exhaust hole.

[0020] A second aspect of the present invention provides a battery pack, comprising the battery cell described in any of the above technical solutions.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The cover plate assembly in the battery cell of the present invention includes a first cover plate, a second cover plate, a pole and a pressure relief member. The first cover plate and the second cover plate are installed on the shell, the pole is arranged on the first cover plate, and the pressure relief member is arranged on the second cover plate, so as to realize that the pole and the pressure relief member are installed on different cover plates, thereby reducing the risk of arcing and fire at the pole position when the battery cell has thermal runaway, and improving the safety performance of the battery cell and the battery pack. In addition, the pole and the pressure relief member are installed on different cover plates, so that only an insulating member covering the pole group is arranged between the second cover plate and the pole group, and compared with the traditional battery cell, the space occupied by the end plate and the lower plastic on one side is omitted, thereby increasing the effective space inside the battery cell, increasing the battery cell capacity, and making the battery pack endurance meet user needs.

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 An exploded diagram of the structure of a battery cell in the prior art;

[0026] Figure 2 An exploded diagram of the structure of a battery cell provided in an embodiment of the present invention.

[0027] Icons: 10-shell; 20-pole group; 21-positive electrode tab; 22-negative electrode tab; 30-insulating part; 41-first cover plate; 42-second cover plate; 43-pole column; 431-positive electrode column; 432-negative electrode column; 44-pressure relief part; 45-plastic part; 46-liquid injection hole; 1-positive electrode cover plate; 2-negative electrode cover plate; 3-lower plastic; 4-electrode assembly; 5-end plate; 6-bare battery cell insulating film; 7-explosion-proof valve; 8-shell. DETAILED DESCRIPTION

[0028] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be apparent. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but in addition to the operations that must occur in a particular order, changes that will be apparent after understanding the disclosure of the present application may be made. In addition, in order to improve clarity and brevity, descriptions of features known in the art may be omitted.

[0029] The features described herein may be implemented in different forms and should not be interpreted as being limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0030] Throughout the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, “bound to”, “over”, or “covering” another element, it may be directly “on”, “connected to”, “bound to”, “over”, or “covering” another element, or one or more other elements may be present between them. In contrast, when an element is described as being “directly on”, “directly connected to”, “directly bound to”, “directly over”, or “directly covering” another element, there may be no other elements present between them.

[0031] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0032] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, component, region, layer, or portion referred to may also be referred to as the second member, component, region, layer, or portion.

[0033] For ease of description, spatial relational terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatial relational terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to the other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relational terms used herein will be interpreted accordingly.

[0034] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and / or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0035] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

[0036] The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0037] According to a first aspect of the present invention, a battery cell is provided, which specifically includes a housing 10, a pole group 20, an insulating member 30 and a cover assembly.

[0038] Hereinafter, the specific structures of the components described above in the battery cell according to the present embodiment will be described.

[0039] In this embodiment, if Figure 2 As shown, a cavity is formed inside the shell 10, and openings are provided at both ends of the cavity. The pole group 20 is arranged in the shell 10. The shell 10 is made of metal material. The insulating member 30 is coated on the pole group 20 to separate the pole group 20 and the shell 10 to form insulation protection. The insulating member 30 can be an insulating film.

[0040] In this embodiment, if Figure 2As shown, the cover plate assembly includes a first cover plate 41, a second cover plate 42, a pole 43 and a pressure relief member 44. The first cover plate 41 and the second cover plate 42 are installed on the housing 10. The first cover plate 41 and the second cover plate 42 are both formed into a plate-like structure. When the housing 10 is a rectangular parallelepiped, the first cover plate 41 and the second cover plate 42 are both formed into a rectangular plate-like structure and are respectively formed as a surface of the rectangular parallelepiped. The pressure relief member 44 can be an explosion-proof valve.

[0041] Specifically, in this embodiment, Figure 2 As shown, the pole 43 is arranged on the first cover plate 41, and the pressure relief member 44 is arranged on the second cover plate 42, so that the pole 43 and the pressure relief member 44 are installed on different cover plates, thereby reducing the risk of arcing and fire at the position of the pole 43 when the battery cell has thermal runaway, thereby improving the safety performance of the battery cell. In addition, in this embodiment, the pole 43 and the pressure relief member 44 are installed on different cover plates, so that only the pressure relief member 44 is arranged on the second cover plate 42, so that only the insulating member 30 covering the electrode group 20 is arranged between the second cover plate 42 and the electrode group 20, which saves the conventional battery cell structure. Figure 1 The space occupied by the end plate 5 and the lower plastic 3 on one side of the positive electrode cover plate 1 is increased, thereby increasing the space occupied by the electrode group 20 in the length direction inside the battery cell, thereby improving the energy density of the battery cell.

[0042] It should be noted that in this embodiment, after the insulating member 30 is covered, only the side facing the first cover plate 41 is provided with an opening, so that the circumferential side wall of the pole group 20 and the side facing the second cover plate 42 are both covered by the insulating member 30 .

[0043] More specifically, in this embodiment, the proportion of the electrode group 20 in the housing 10 is increased by W, W = (W1-W0) / W0 = 1.5% to 3.0%, W0 is the length of the electrode group 20 in the conventional battery cell, that is, the electrode group in the conventional battery cell (i.e. Figure 1 The electrode assembly 4 in the housing (i.e. Figure 1 W0 is the dimension in the length direction of the shell 8 in the shell, W1 is the length dimension of the electrode group 20 in the battery cell of the present application, that is, the dimension of the electrode group 20 in the length direction of the shell 10 on the shell 10 in the present application, and the units of W0 and W1 are both mm.

[0044] The following are multiple groups of comparative tests on the length size and safety of the pole group 20 of the battery cell structure of the present application and the traditional battery cell structure with poles 43 arranged on both sides and end plates and two lower plastics. Five groups of similar batteries are used in each group of tests to ensure the reliability and accuracy of the test. The test results are shown in Table 1 below.

[0045] Table 1

[0046]

[0047] As shown in Table 1, in Tests 1 to 5, the length of the pole group 20 in the battery cell structure of the present application is increased compared to the pole group 20 in the traditional battery cell, so that the proportion of the pole group 20 inside the shell 10 is effectively increased, thereby increasing the energy density of the battery cell compared to the traditional battery cell structure, and being able to improve or maintain the test pass rate in the battery cell safety inspection, thereby demonstrating that the battery cell structure of the present application has reliable safety performance and can improve the problems caused by thermal runaway of the battery cell to a certain extent.

[0048] In a preferred embodiment, Figure 2 As shown, the first cover plate 41 and the second cover plate 42 are arranged parallel to each other, so that the first cover plate 41 and the second cover plate 42 are arranged opposite to each other, so that when thermal runaway occurs in the battery cell, the gas inside the battery cell is ejected toward the pressure relief member 44, and the ejection direction is away from the pole 43, thereby avoiding the high temperature and high pressure gas from affecting the pole 43.

[0049] Furthermore, in this embodiment, the first cover plate 41 and the second cover plate 42 are arranged opposite to each other at both ends of the shell 10 in the length direction, so as to maximize the distance between the pole 43 and the pressure relief member 44, thereby achieving effective protection for the pole 43 in the event of thermal runaway.

[0050] Furthermore, in this embodiment, if Figure 2 As shown, the cover assembly also includes a plastic part 45, which is made of insulating material, such as PP (polypropylene), and is arranged on the side of the first cover 41 facing the inside of the battery cell, and is used to separate the first cover 41 from the pole group 20. The insulating part 30 is hot-melt connected to the plastic part 45, so that the insulating part 30 and the plastic part 45 can effectively separate the pole group 20 and the pole 43 from the shell 10 to improve the insulation effect.

[0051] It should be noted that, in the present embodiment, since only a pressure relief member 44 is provided on the second cover plate 42 and no pole 43 is provided, only the insulating member 30 is required to separate the second cover plate 42 and the pole group 20, and there is no need to provide a plastic member 45 on the side of the second cover plate 42 facing the interior of the battery cell. Therefore, compared with the traditional long battery cell structure, the battery cell structure of the present application only needs to provide a plastic member 45 on one side of the pole group 20, thereby saving the effective space inside the battery cell.

[0052] Furthermore, in this embodiment, if Figure 2 As shown, the electrode group 20 is formed into a rectangular block structure, and a protruding electrode ear is provided on the electrode group 20, and the electrode ear includes a positive electrode ear 21 and a negative electrode ear 22. In this embodiment, the positive electrode ear 21 and the negative electrode ear 22 are arranged on the same side of the electrode group 20, that is, the positive electrode ear 21 and the negative electrode ear 22 extend outward on the same side of the electrode group 20.

[0053] Furthermore, in this embodiment, if Figure 2 As shown, the pole 43 includes a positive pole 431 and a negative pole 432, the positive pole 431 is connected to the positive pole ear 21, and the negative pole 432 is connected to the negative pole ear 22, the positive pole 431 and the negative pole 432 are arranged at intervals on the first cover plate 41, and when the first cover plate 41 is formed into a rectangular plate structure, the positive pole 431 and the negative pole 432 are arranged on both sides of the first cover plate 41 in the length direction.

[0054] In this embodiment, if Figure 2 As shown, the first cover plate 41 is provided with an injection hole 46, which is formed as a through hole penetrating the first cover plate 41. After the battery cell is assembled, electrolyte can be injected into the battery cell from the outside through the injection hole 46 and vacuum can be drawn. In addition, the second cover plate 42 is provided with an exhaust hole, which is a through hole penetrating the second cover plate 42, and is used to discharge the gas inside the battery cell to the outside of the battery cell when the battery cell is in thermal runaway. The pressure relief member 44 is installed in the exhaust hole, so that the structure in the cover plate assembly is realized in which only the pressure relief member 44 is installed on the second cover plate 42. When the battery cell is in thermal runaway, the gas inside the battery cell is ejected to the pressure relief member 44, so as to prevent the pole 43 from arcing and catching fire due to the influence of high temperature and high pressure gas, aggravating the thermal runaway of the battery cell, thereby improving the safety performance of the battery cell.

[0055] In this embodiment, a folding pole ear space is provided between the pole column 43 and the pole group 20, so that the pole column 43 and the pole group 20 are spaced apart in the length direction of the battery cell, and the folding pole ear space is used for bending the pole ear after the pole ear and the pole column 43 are assembled to facilitate the pole group 20 to enter the shell. In this embodiment, the size of the folding pole ear space in the thickness direction of the first cover plate 41 is 6mm to 8mm, while the space for bending the pole ear required in the traditional battery cell structure is usually between 14mm and 17mm, so the battery cell structure of the present application can save 6mm to 11mm compared with the traditional battery cell structure, so that the saved space can be used to increase the volume of the pole group 20 in the length direction of the battery cell.

[0056] In the present embodiment, the first cover plate 41 and the second cover plate 42 are respectively welded to the shell 10; specifically, the assembly order of the battery cell in the present application is: the shell 10 is welded to the second cover plate 42, the pole ear is welded to the pole post 43 on the first cover plate 41, the pole ear is bent to form the pole group 20, the pole group 20 is covered with the insulating member 30, the pole group 20 is put into the shell, and the first cover plate 41 is welded to the shell 10, which greatly simplifies the assembly process flow. Such an arrangement makes it possible that in the present embodiment, after the second cover plate 42 is welded to the shell 10, the first cover plate 41 is welded to the shell 10, so that the second cover plate 42 with only the pressure relief member 44 can be welded to the shell 10 first, so that the second cover plate 42 and the shell 10 welding defective products can be discharged in advance, and the whole battery cell can be scrapped when the second cover plate 42 and the shell 10 are poorly welded after the first cover plate 41 and the shell 10 have been welded, thereby reducing the production cost.

[0057] According to a battery cell provided by the present invention, the structure is simple and easy to assemble, wherein the cover plate assembly includes a first cover plate, a second cover plate, a pole and a pressure relief member, the first cover plate and the second cover plate are installed on the shell, the pole is arranged on the first cover plate, and the pressure relief member is arranged on the second cover plate, so that the pole and the pressure relief member are installed on different cover plates, thereby reducing the risk of arcing and fire at the pole position when the battery cell has thermal runaway, and improving the safety performance of the battery cell. In addition, the pole and the pressure relief member are installed on different cover plates, so that only an insulating member covering the pole group is arranged between the second cover plate and the pole group, and compared with the traditional battery cell, the space occupied by the end plate and the lower plastic on one side is saved, thereby increasing the effective space inside the battery cell and increasing the battery cell capacity.

[0058] A battery pack provided according to the present invention includes the battery cell as described above, wherein at least one battery cell is provided. When a plurality of battery cells are provided, at least some of the battery cells are connected in series and / or in parallel, and the safety performance and capacity of each battery cell are effectively improved, so that the battery pack has reliable safety performance and endurance.

[0059] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes 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, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A battery cell, characterized in that: The battery cell comprises: case; A pole group is arranged in the shell; An insulating member, covering the pole group; The cover plate assembly includes a first cover plate, a second cover plate, a pole and a pressure relief member, wherein the pole is arranged on the first cover plate, the pressure relief member is arranged on the second cover plate, the first cover plate and the second cover plate are installed on the shell, and only the insulating member is arranged between the second cover plate and the pole group.

2. The battery cell according to claim 1, characterized in that: The cover plate assembly also includes: The plastic component is arranged on a side of the first cover plate facing the inside of the battery core, and the insulating component is connected to the plastic component by thermal melting.

3. The battery cell according to claim 1, characterized in that: The pole group is provided with protruding pole ears, and the pole ears include a positive pole ear and a negative pole ear, and the positive pole ear and the negative pole ear are arranged on the same side of the pole group.

4. The battery cell according to claim 3, characterized in that: A folded pole ear space is provided between the pole column and the pole group, and a dimension of the folded pole ear space in a thickness direction of the first cover plate is 6 mm to 8 mm.

5. The battery cell according to claim 1, characterized in that: The poles include a positive pole and a negative pole, and the positive pole and the negative pole are spaced apart from each other on the first cover plate.

6. The battery cell according to claim 1, characterized in that: The first cover plate and the second cover plate are respectively connected to the shell by welding; after the second cover plate is welded to the shell, the first cover plate is welded to the shell.

7. The battery cell according to claim 1, characterized in that: The first cover plate and the second cover plate are arranged parallel to each other.

8. The battery cell according to claim 7, characterized in that: The first cover plate and the second cover plate are disposed opposite to each other at two ends in the length direction of the housing.

9. The battery cell according to claim 1, characterized in that: The first cover plate is provided with a liquid injection hole, the second cover plate is provided with an exhaust hole, and the pressure relief member is installed at the exhaust hole.

10. A battery pack, characterized in that: A battery cell comprising any one of claims 1 to 9.

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