Battery cover and battery

Abstract

The present invention relates to the field of battery technology, and in particular to a cell cover and a cell. The cell cover comprises: one end of the pole is formed as a riveted portion; the connecting hole on the riveted piece is a stepped hole having a first step section and a second step section, the pole is riveted with the riveted piece, so that part of the riveted portion expands in the direction close to the second step section; before riveting, the size of the riveted portion in the thickness direction of the cover body is m, and the total size of the first step section and the second step section in the thickness direction of the cover body is n, (m‑n) / n=0.15~0.3. The present invention ensures that the pole and the riveted piece have sufficient expansion after riveting, so that the push-pull force that the pole can withstand meets the use requirements of the cell cover, ensures the safety performance of the cell, and can also avoid the problem of excessive expansion of the pole after riveting, resulting in the cell cover size out of tolerance, and ensures that the size accuracy and shape accuracy of the cell cover meet the design requirements, thereby improving the production yield of the cell cover.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cover and a battery. 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. The lithium battery cover is a key accessory in lithium-ion batteries. It has the functions of welding with the shell to form a sealed cavity, leading the positive and negative electrodes of the electrode group, and serving as an assembly carrier. The traditional cover includes a riveting block, a pole and a top cover sheet. The pole is fixed on the top cover sheet by riveting with the riveting block. Therefore, the riveting quality of the pole and the riveting block affects the assembly quality of the cover. If the pole is insufficiently expanded after riveting, the push and pull force that the pole can withstand will be reduced, and the risk of subsequent poor welding with the riveting block will increase, and the safety of battery use cannot be guaranteed; if the pole and the riveting block are over-riveted, it is easy to cause deformation of the cover and serious dimensional deviation, and the production yield of the cover will decrease, affecting the subsequent assembly with the shell. Summary of the invention

[0003] In view of this, the purpose of the present application is to provide a battery cell cover and a battery cell, so as to solve the problem that the pole and the rivet block in the existing battery cell cover are easily reduced in push-pull force due to insufficient expansion of the pole after riveting, and there is a risk of poor welding. It is also easy for the pole and the rivet block to be over-riveted, resulting in deformation of the cover and serious dimensional deviations, affecting the production yield of the battery cell cover.

[0004] A first aspect of the present invention provides a cell cover, wherein the cell cover comprises:

[0005] The cover plate body is provided with a mounting hole;

[0006] A pole, arranged in the mounting hole, wherein one end of the pole extending out of the cover plate body and facing the outside of the battery cell is formed into a riveted portion;

[0007] A rivet is provided with a connection hole, the rivet portion is arranged in the connection hole, the connection hole is formed as a stepped hole, the connection hole includes a first step section and a second step section arranged in sequence along the axial direction, the radial dimension of the second step section is greater than the radial dimension of the first step section, the pole is riveted to the rivet, so that part of the rivet portion expands toward the direction close to the second step section;

[0008] Before riveting, the dimension of the riveted portion in the thickness direction of the cover plate body is m, and the total dimension of the first step section and the second step section in the thickness direction of the cover plate body is n, (mn) / n=0.15-0.3.

[0009] Preferably, the pole includes a column portion and a plate portion arranged in sequence along the axial direction; the column portion is passed through the mounting hole and the end of the column portion extending out of the cover plate body facing the outside of the battery cell is formed as the riveted portion; the plate portion is arranged at one end of the cover plate body facing the inside of the battery cell.

[0010] Preferably, part of the circumferential side wall of the column portion protrudes outward to form a boss portion, and the rivet is in abutment with one end of the boss portion facing the outside of the battery cell.

[0011] Preferably, the connecting hole further comprises a third step segment, the third step segment is arranged at an end of the second step segment facing away from the first step segment, and a radial dimension of the third step segment is greater than a radial dimension of the second step segment.

[0012] Preferably, before riveting, part of the riveted portion extends out of a side of the riveted member facing the outside of the battery cell.

[0013] Preferably, after riveting, the pole is connected to the riveted piece by welding to form a welding portion between the outer wall of the riveted portion and the second step section.

[0014] Preferably, the cell cover plate further includes:

[0015] The first insulating member is sandwiched between the rivet member and the cover plate body, and a portion of the first insulating member extends toward the rivet member to cover the circumferential side wall of the rivet member.

[0016] Preferably, the cell cover plate further comprises:

[0017] The second insulating member is arranged on a side of the cover plate body facing the inside of the battery cell, and a portion of the second insulating member is sandwiched between the cover plate body and the plate body.

[0018] Preferably, the cell cover plate further comprises:

[0019] A sealing member is sleeved on the circumferential side wall of the column portion, and a portion of the sealing member is sandwiched between the plate portion and the cover plate body.

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

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

[0022] The cell cover of the present invention satisfies the relationship between the size m of the riveted portion and the riveted block on the pole before riveting and the total size n of the first step section and the second step section related to the riveting on the connecting hole to satisfy (mn) / n=0.15~0.3, so that the pole and the riveted piece have sufficient expansion after riveting, and the riveting of the pole and the riveted piece is reliable, so that the push-pull force that the pole can withstand meets the use requirements of the cell cover, and the safety performance of the battery cell is guaranteed. It can also avoid the problem of excessive expansion of the pole after riveting, resulting in excessive size of the cell cover, and ensure that the size accuracy and shape accuracy of the cell cover meet the design requirements, thereby improving the production yield of the cell cover, and further ensuring the product quality of the battery cell.

[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 A schematic diagram of the exploded structure of a cell cover provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the structure of a pole in a cell cover plate before riveting provided by an embodiment of the present invention;

[0027] Figure 3 For along Figure 2 The cross-section taken at AA in the middle;

[0028] Figure 4 A schematic diagram of the structure of a riveted part in a cell cover provided by an embodiment of the present invention;

[0029] Figure 5 For along Figure 4 The cross-section taken at BB in the middle;

[0030] Figure 6 A schematic diagram of the structure of a cell cover plate before riveting provided by an embodiment of the present invention;

[0031] Figure 7 For along Figure 6 Cross-sectional view taken at CC;

[0032] Figure 8 A schematic diagram of the structure of a cell cover plate after riveting provided by an embodiment of the present invention;

[0033] Fig. 9 A cross-sectional view of a cell cover plate after riveting provided by an embodiment of the present invention.

[0034] Icons: 10-cover body; 11-mounting hole; 12-liquid injection hole; 20-pole; 21-column; 211-riveted part; 212-boss; 22-plate body; 30-rivet; 31-connecting hole; 311-first step section; 312-second step section; 313-third step section; 41-first insulating part; 42-second insulating part; 50-sealing part. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] 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.

[0038] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] According to a first aspect of the present invention, a cell cover is provided, which specifically includes a cover body 10 , a pole 20 and a rivet 30 .

[0045] Hereinafter, the specific structure of the cell cover plate as described above according to this embodiment will be described.

[0046] In this embodiment, if Figure 1 As shown, the cover body 10 is formed into a plate-like structure. Specifically, when the battery cell is a square shell battery cell or a blade battery cell, the cover body 10 is a rectangular plate-like structure. The cover body 10 is welded to the battery cell shell, and a mounting hole 11 is opened on the cover body 10. The mounting hole 11 is a through hole structure that penetrates the cover body 10.

[0047] Optionally, a liquid injection hole 12 is opened on the cover body 10 , and the liquid injection hole 12 is a through-hole structure penetrating the cover body 10 . After the battery cover and the battery shell are assembled, electrolyte can be injected into the battery cell through the liquid injection hole 12 .

[0048] like Figure 7 and Fig. 9 As shown, the pole 20 is arranged in the mounting hole 11, and the end of the pole 20 extending out of the cover body 10 facing the outside of the battery cell is formed as a riveted portion 211; the rivet 30 is formed as a block structure, and a connecting hole 31 is opened on the rivet 30, and the connecting hole 31 is formed as a through hole structure penetrating the rivet 30, and the rivet portion 211 is arranged in the connecting hole 31.

[0049] Specifically, Figure 4 , Figure 5 , Figure 7 and Fig. 9 As shown, the hole is formed as a stepped hole, and the connecting hole 31 includes a first step section 311 and a second step section 312 arranged in sequence along the axial direction, wherein the radial dimension of the second step section 312 is greater than the radial dimension of the first step section 311, and the first step section 311 is arranged facing the cover body 10, and the pole 20 is riveted with the rivet 30, so that part of the riveted portion 211 expands toward the direction close to the second step section 312, so that the pole 20 is fixed to the cover body 10 by using the rivet 30.

[0050] In this embodiment, if Figures 2 to 7 As shown, the dimension of the riveted portion 211 in the thickness direction of the cover body 10 before riveting is m, in mm; the total dimension of the first step section 311 and the second step section 312 in the thickness direction of the cover body 10 is n, in mm, (mn) / n=0.15~0.3, so that the pole 20 and the rivet 30 have sufficient expansion after riveting, ensuring that the pole 20 and the rivet 30 are riveted reliably, so that the push-pull force that the pole 20 can withstand meets the use requirements of the battery cover, ensuring the safety performance of the battery, and also avoiding the problem of excessive expansion of the pole 20 after riveting, resulting in the size of the battery cover exceeding the tolerance, ensuring that the size accuracy and shape accuracy of the battery cover meet the design requirements, thereby improving the production yield of the battery cover, and then ensuring the product quality of the battery.

[0051] In this embodiment, if Figure 7 As shown, before riveting, part of the riveted portion 211 extends out of the side of the rivet 30 facing the outside of the battery cell, which further ensures that the pole 20 and the rivet 30 have sufficient expansion after riveting, improves the riveting reliability of the pole 20 and the rivet 30, and makes the push and pull force that the pole 20 can withstand meet the use requirements of the battery cover, thereby ensuring the safety performance of the battery cell.

[0052] In this embodiment, if Figure 7 As shown, before riveting, the basic dimension of the riveted portion 211 in the radial direction is the same as the basic dimension of the first step section 311 in the radial direction, and the basic dimension is the dimension given in the design.

[0053] It should be noted that the axial direction is the thickness direction of the cover plate body 10 , and the radial direction is perpendicular to the thickness direction of the cover plate body 10 .

[0054] Specifically, in this embodiment, Figure 1 , Figure 3 , Figure 4 , Figure 7 and Fig. 9 As shown, the pole 20 includes a column portion 21 and a plate portion 22 arranged in sequence along the axial direction. The column portion 21 can be a cylindrical or prismatic structure. The column portion 21 is inserted into the mounting hole 11 and the end of the column portion 21 extending out of the cover body 10 facing the outside of the battery cell is formed as a riveted portion 211; the plate portion 22 is arranged at the end of the cover body 10 facing the inside of the battery cell. The plate portion 22 can be a polygonal, circular or elliptical plate-like structure, which is used to connect the pole ears on the pole group inside the battery cell. The plate-like structure can increase the connection area and facilitate welding and assembly with the pole ears.

[0055] More specifically, in this embodiment, if Figure 3 , Figure 7 and Fig. 9 As shown, part of the circumferential side wall of the column portion 21 protrudes outward to form a boss portion 212, so that before riveting, the radial dimension of the boss portion 212 is greater than the radial dimension of the rivet portion 211, and the rivet 30 abuts against one end of the boss portion 212 facing the outside of the battery cell, thereby limiting the rivet 30. In this embodiment, the rivet portion 211, the boss portion 212 and the plate portion 22 are arranged in sequence along the axial direction of the pole 20.

[0056] In this embodiment, if Figure 8 and Fig. 9As shown, after riveting, the pole 20 is welded to the rivet 30 to form a welding portion between the outer wall of the rivet portion 211 and the second step section 312, so as to ensure that the pole 20 and the rivet 30 are connected reliably, and the push and pull force that the pole 20 can withstand is increased, so that the pole 20 has sufficient structural strength to resist external impact. It should be noted that the welding portion can be understood as a welding mark formed under the welding process.

[0057] Furthermore, if Figure 5 As shown, the connecting hole 31 also includes a third step section 313, and the third step section 313 is arranged at one end of the second step section 312 facing away from the first step section 311, and the radial dimension of the third step section 313 is greater than the radial dimension of the second step section 312, so as to avoid the welding part protruding from the outer surface of the rivet 30, improve the appearance of the battery cover, and improve the yield rate of the battery cover.

[0058] In this embodiment, if Figure 1 , Figures 6 to 9 As shown, the cell cover also includes a first insulating member 41, and the first insulating member 41 is clamped between the rivet 30 and the cover body 10, thereby separating the rivet 30 and the cover body 10 to provide insulation protection for the cover body 10 and reduce the risk of short circuit. In addition, part of the first insulating member 41 extends toward the rivet 30 to cover the circumferential side wall of the rivet 30, thereby improving the insulation protection effect. It should be noted that the problem of excessive material expansion of the pole 20 after riveting, resulting in out-of-tolerance size of the cell cover, mainly occurs when the rivets 30 on both sides of the pole 20 in the width direction of the cover body 10 are greatly deformed, causing the first insulating member 41 to deform accordingly. Figure 8 The width dimension of the first insulating member 41 located on both sides of the pole 20 in the width direction of the cover body 10 is B, that is, the measurement position of dimension B passes through the pole 20, and the deformation of the position of dimension B is more obvious than that of other positions.

[0059] In the following, when the size of the rivet 30 is fixed, the size of m is adjusted and the size B of the first insulating member 41 at the riveted area and the push-pull force that the pole 20 can withstand are detected to verify whether the limiting condition (mn) / n=0.15~0.3 ensures reliable riveting assembly of the pole 20. The following multiple tests are performed.

[0060] Test 1: n=2.3 mm, the dimension requirement of the first insulating member 41 in the width direction of the cover plate is 12.5±0.2 mm, the push-pull force requirement that the pole 20 can withstand is ≥1000 N, and the test results are shown in Table 1.

[0061] Table 1

[0062]

[0063] Test 2: n=2.8 mm, the dimension requirement of the first insulating member 41 in the width direction of the cover plate is 13.5±0.2 mm, the push-pull force requirement that the pole 20 can withstand is ≥1000 N, and the test results are shown in Table 2.

[0064] Table 2

[0065]

[0066] Test 3: n=2mm, the dimension requirement of the first insulating member 41 in the width direction of the cover plate is 11.5±0.2mm, the push-pull force requirement that the pole 20 can withstand is ≥800N, and the test results are shown in Table 3.

[0067] Table 3

[0068]

[0069] Referring to Tables 1 to 3 above, it can be seen that in Examples 1-4 to 1-8, Examples 2-4 to 2-8, and Examples 3-4 to 3-7, (mn) / n is within the limited range of 0.15~0.3, and the dimension B of the first insulating member 41 in the width direction of the cover plate after riveting meets the set dimension requirements, and the maximum push-pull force that the pole 20 can withstand is higher than the set push-pull force requirements. This proves that the limiting condition of (mn) / n=0.15~0.3 can effectively ensure the reliability of the riveted assembly of the pole 20, so that the push-pull force that the pole 20 can withstand meets the use requirements of the battery cover plate, ensures the safety performance of the battery cell, and can also avoid the problem of excessive expansion of the pole 20 after riveting, resulting in excessive size of the battery cover plate, ensuring that the size accuracy and shape accuracy of the battery cover plate meet the design requirements, thereby improving the production yield of the battery cover plate.

[0070] In Examples 1-1 to 1-3, 2-1 to 2-3, and 3-1 to 3-3, the parameter (mn) / n is less than 0.15, resulting in the maximum push-pull force that the pole 20 can withstand being less than the set requirement, thereby failing to ensure the safety performance of the battery cell. In Examples 1-9, 1-10, 2-9, 2-10, 3-8 to 3-10, the parameter (mn) / n is greater than 0.3, resulting in excessive expansion of the pole 20, and the dimension B after riveting exceeds the set dimension range, reducing the production yield of the battery cell cover.

[0071] In addition, in this embodiment, Figure 1 , Figures 6 to 9As shown, the cell cover also includes a second insulating member 42, which is arranged on the side of the cover body 10 facing the inside of the cell to provide insulation protection for the cell cover and prevent the pole group and other components inside the cell from contacting the cover body 10 and causing a short circuit. Part of the second insulating member 42 is sandwiched between the cover body 10 and the plate body 22, so that the cover body 10 can be separated from the plate body 22, thereby further preventing the pole 20 from contacting the cover body 10 and causing a short circuit.

[0072] In this embodiment, the first insulating member 41 and the second insulating member 42 are both made of insulating materials, such as PP (polypropylene) or PPS (polyphenylene sulfide).

[0073] In addition, in this embodiment, Figure 1 , Figures 6 to 9 As shown, the cell cover also includes a seal 50, which can be an annular sealing ring. The seal 50 is sleeved on the circumferential side wall of the column portion 21, so that part of the seal 50 is clamped between the mounting hole 11 and the boss portion 212, and the remaining part of the seal 50 is clamped between the plate portion 22 and the cover body 10, so as to ensure the sealing of the cell cover assembly.

[0074] According to a battery cell cover provided by the present invention, by limiting the relationship between the size m of the riveted portion and the riveted block on the pole before riveting and the total size n of the first step section and the second step section related to the riveting on the connecting hole to satisfy (mn) / n=0.15~0.3, it is achieved that the pole and the riveted part have sufficient expansion after riveting, and the riveting of the pole and the riveted part is reliable, so that the push and pull force that the pole can withstand meets the use requirements of the battery cell cover, and the safety performance of the battery cell is guaranteed, and it can also avoid the problem of excessive expansion of the pole after riveting, resulting in excessive size of the battery cell cover, and ensure that the size accuracy and shape accuracy of the battery cell cover meet the design requirements, thereby improving the production yield of the battery cell cover, and then ensuring the product quality of the battery cell.

[0075] A battery cell provided according to the present invention comprises the battery cell cover plate as described above, and thus has all the beneficial effects of the battery cell cover plate, which will not be described in detail herein.

[0076] 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 cover, characterized in that: The battery cover plate comprises: The cover plate body is provided with a mounting hole; A pole, arranged in the mounting hole, wherein one end of the pole extending out of the cover plate body and facing the outside of the battery cell is formed into a riveted portion; A rivet is provided with a connection hole, the rivet portion is arranged in the connection hole, the connection hole is formed as a stepped hole, the connection hole includes a first step section and a second step section arranged in sequence along the axial direction, the radial dimension of the second step section is greater than the radial dimension of the first step section, the pole is riveted to the rivet, so that part of the rivet portion expands toward the direction close to the second step section; Before riveting, the dimension of the riveted portion in the thickness direction of the cover plate body is m, and the total dimension of the first step section and the second step section in the thickness direction of the cover plate body is n, (mn) / n=0.15~0.3; The pole comprises a column part and a plate part arranged in sequence along the axial direction; the column part is inserted into the mounting hole and the end of the column part extending out of the cover plate body facing the outside of the battery cell is formed as the riveted part; the plate part is arranged at the end of the cover plate body facing the inside of the battery cell; Part of the circumferential side wall of the column portion protrudes outward to form a boss portion, and the rivet is in contact with one end of the boss portion facing the outside of the battery cell; The connecting hole further comprises a third step section, the third step section is arranged at an end of the second step section facing away from the first step section, and the radial dimension of the third step section is greater than the radial dimension of the second step section; The battery cover plate also includes: A first insulating member, sandwiched between the rivet member and the cover plate body, wherein a portion of the first insulating member extends toward the rivet member to cover a circumferential side wall of the rivet member; A second insulating member is arranged on a side of the cover plate body facing the inside of the battery cell, and a portion of the second insulating member is sandwiched between the cover plate body and the plate body; A sealing member is sleeved on the circumferential side wall of the column portion, and a portion of the sealing member is sandwiched between the plate portion and the cover plate body.

2. The cell cover plate according to claim 1, characterized in that: Before riveting, part of the riveted portion extends out of a side of the riveted piece facing the outside of the battery cell.

3. The cell cover plate according to claim 1, characterized in that: After riveting, the pole is connected to the riveted piece by welding to form a welding portion between the outer wall of the riveted portion and the second step section.

4. A battery cell, characterized in that: The invention comprises the battery cell cover plate as claimed in any one of claims 1 to 3.

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