Battery cell shell and battery cell

Abstract

The utility model relates to the technical field of batteries, in particular to a battery cell shell and a battery cell. The battery cell shell comprises: a shell main body, which is provided with a mounting hole, the mounting hole is provided with an extension part protruding towards the outside of the shell main body and a necking part extending towards the inside of the mounting hole from the inner wall of the extension part, so that the mounting hole forms a step-shaped structure; the pressure relief piece is embedded in the mounting hole, and the pressure relief piece abuts against the side, facing the interior of the shell body, of the necking part. According to the battery cell shell disclosed by the utility model, the assembly of the pressure relief piece and the shell main body is realized under the condition that the thickness of the shell main body is not changed, so that the problems that the capacity of the battery cell is reduced and the weight is increased due to increase of the thickness of the shell are avoided, and the yield and the production efficiency of the battery cell are further improved; and the battery cell shell integrating the shell main body and the pressure relief piece can be used for arranging the pressure relief piece at the bottom, so that the overall safety of the battery cell can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a battery core shell and a battery core. Background Art

[0002] With the continuous development of the application of lithium batteries in the automotive power industry, higher requirements are placed on the safety performance of batteries. Traditional batteries usually set the pressure relief mechanism of the battery cell, that is, the safety explosion-proof valve, on the top cover of the battery cell. When the battery cell triggers thermal runaway, gas is rapidly generated inside the battery cell, so it is necessary to open the explosion-proof valve to discharge the gas inside the battery cell to reduce the internal pressure of the battery cell. At this time, the electrolyte inside the battery cell may spray out or even cause safety risks such as fire. Therefore, integrating the explosion-proof valve at the bottom of the shell can improve the overall safety of the battery cell. However, due to the welding of the explosion-proof valve on the side wall of the shell, the shell must have sufficient wall thickness to set a step to accommodate the welding and fixing of the explosion-proof valve. Therefore, the shell with a bottom explosion-proof valve structure is mostly welded. The wall thickness on one side of the explosion-proof valve will be greater than the wall thickness of the other several sides, resulting in a reduction in the battery cell capacity. At the same time, the weight of the shell will also increase. In addition, the production and manufacturing process of this type of shell is immature, with low yield and slow efficiency, which increases the cost. Utility Model Content

[0003] In view of this, the purpose of the present application is to provide a battery cell shell and a battery cell to solve the problem that the existing battery cell with an explosion-proof valve on the shell is thickened due to the welding of the explosion-proof valve, resulting in reduced battery cell capacity and increased weight, resulting in low yield, slow efficiency and high cost in battery cell production.

[0004] The first aspect of the utility model provides a battery cell shell, wherein the battery cell shell comprises:

[0005] The shell body is provided with a mounting hole, wherein the mounting hole has an extension portion protruding toward the outside of the shell body and a constricted portion extending from the inner wall of the extension portion toward the inside of the mounting hole, so that the mounting hole is formed into a step-like structure;

[0006] The pressure relief member is embedded in the mounting hole, and the pressure relief member abuts against a side of the neck portion facing the interior of the shell body.

[0007] Preferably, the housing body is formed as a rectangular housing structure, and the side wall of the housing body includes two large faces opposite to each other and two narrow faces opposite to each other, and the large face is arranged adjacent to the two narrow faces;

[0008] The mounting hole is arranged on the narrow surface.

[0009] Preferably, the extension portion and the necking portion are both formed into a closed annular structure, and the necking portion is arranged at an end of the extension portion away from the shell body;

[0010] And / or, the necked portion extends along a first direction, the extending portion extends along a second direction, and the first direction is perpendicular to the second direction.

[0011] Preferably, the wall thickness of the mounting hole is the same as the wall thickness of the shell body.

[0012] Preferably, the adjacent two side walls of the shell body are connected by an arc-shaped transition portion;

[0013] A detection portion is formed on the side wall of the shell body where the mounting hole is opened. The detection portion is arranged between the transition portion and the extension portion. The size of the detection portion in the first direction is A, 1mm≤A≤5mm.

[0014] Preferably, the adjacent two side walls of the shell body are arranged perpendicular to each other, and the central angle of the transition portion is 90°;

[0015] The dimension of the pressure relief component in the first direction is L1=L0-(δ+R+A+C+0.5)×2, wherein L0 is the dimension of the shell body in the first direction; δ is the wall thickness of the shell body, δ=0.2mm~0.8mm; R is the radius of the inner wall of the transition portion; C is the gap between the pressure relief component and the extension portion, 0.1mm≤C≤0.5mm.

[0016] Preferably, a dimension of the necked portion in the first direction is B≥δ+C+0.5, B≥1.1 mm.

[0017] Preferably, the mounting hole is formed by stamping.

[0018] Preferably, the pressure relief member is formed with a limiting portion protruding outward, the limiting portion is arranged on one side of the inner wall of the necking portion, the pressure relief member is welded to the shell body to form a welding portion between the necking portion and the limiting portion, and the weld width of the welding portion in the first direction is evenly divided between the necking portion and the limiting portion;

[0019] The dimension D of the limiting portion in the first direction is ≥0.5 mm.

[0020] A second aspect of the utility model provides a battery cell, comprising the battery cell shell described in any of the above technical solutions.

[0021] Compared with the prior art, the beneficial effects of the utility model are:

[0022] The battery cell shell of the utility model has a mounting hole provided in the shell body, comprising an extension portion protruding outward and a necking portion extending inward from the inner wall of the extension portion, so that the mounting hole is formed into a step-shaped structure; the pressure relief piece is embedded in the mounting hole, and abuts against a side of the necking portion facing the inside of the shell body, so that the extension portion and the necking portion surround an area for mounting the pressure relief piece, so that the pressure relief piece is mounted on the step surface of the inner wall of the mounting hole, so that the necking portion has the functions of fixing and sealing the shell at the same time, thereby realizing the assembly of the pressure relief piece and the shell body without changing the thickness of the shell body, avoiding the problem of reduced capacity and increased weight of the battery cell due to increased shell thickness, thereby improving the yield rate and production efficiency of the battery cell, and the battery cell shell that integrates the shell body and the pressure relief piece can set the pressure relief piece toward the bottom, thereby improving the overall safety of the battery cell.

[0023] In addition, since the mounting hole is formed as a step-like structure and protrudes from the side wall of the shell body where the mounting hole is provided, the pressure relief part embedded in the mounting hole will not interfere with the components inside the battery cell, avoiding internal scratches on the pressure relief part, thereby reducing the risk of battery cell failure.

[0024] 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

[0025] In order to more clearly illustrate the specific implementation methods of the utility model 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 utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the structure of a battery cell housing provided in an embodiment of the utility model;

[0027] Figure 2 A structural cross-sectional view of the mounting hole of the shell body in the battery shell provided by an embodiment of the utility model;

[0028] Figure 3 A cross-sectional view of the assembly structure of the shell body and the pressure relief member in the battery shell provided by the embodiment of the utility model;

[0029] Figure 4 A structural cross-sectional view of a pressure relief member in a battery cell housing provided by an embodiment of the utility model, which is assembled on a mounting hole.

[0030] Icons: 10 - shell body; 11 - mounting hole; 111 - extension part; 112 - necking part; 101 - large surface; 102 - narrow surface; 103 - transition part; 104 - detection part; 20 - pressure relief part; 21 - limit part; D1 - first direction; D2 - second direction. DETAILED DESCRIPTION

[0031] 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.

[0032] 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.

[0033] 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.

[0034] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] According to a first aspect of the present utility model, a battery cell housing is provided, which includes a housing body 10 and a pressure relief member 20 .

[0041] Hereinafter, the specific structures of the above-mentioned components of the cell case according to the present embodiment will be described.

[0042] In this embodiment, as 1 to Figure 4 As shown, a mounting hole 11 is provided on the shell body 10, and the mounting hole 11 is formed as a through-hole structure penetrating the shell body 10. Specifically, the mounting hole 11 has an extension portion 111 protruding toward the outside of the shell body 10 and a constriction portion 112 extending from the inner wall of the extension portion 111 toward the inside of the mounting hole 11, so that the mounting hole 11 is formed into a step-like structure and protrudes outward from the side wall of the shell body 10 provided with the mounting hole 11. The pressure relief member 20 is embedded in the mounting hole 11, and the pressure relief member 20 abuts against the side of the constriction portion 112 facing the inside of the shell body 10, so that the extension portion 111 and the constriction portion 112 are in contact with each other. 2 encloses an area for installing the pressure relief member 20, so that the pressure relief member 20 is installed on the stepped surface of the inner wall of the installation hole 11, so that the necking portion 112 has the functions of fixing and sealing the shell, thereby realizing a firm assembly of the pressure relief member 20 and the shell body 10 without changing the thickness of the shell body 10, thereby avoiding the problem of reduced capacity and increased weight of the battery cell due to increased wall thickness of the shell, thereby improving the yield rate and production efficiency of the battery cell; in addition, the battery cell shell that integrates the shell body 10 and the pressure relief member 20 can set the pressure relief member 20 toward the bottom, and can also improve the overall safety of the battery cell.

[0043] In this embodiment, if Figure 3 As shown, since the mounting hole 11 is formed as a step-like structure and protrudes from the side wall of the shell body 10 where the mounting hole 11 is provided, the pressure relief member 20 embedded in the mounting hole 11 will not interfere with the components inside the battery cell, avoiding internal scratches on the pressure relief member 20, thereby reducing the risk of battery cell failure.

[0044] In this embodiment, if Figures 1 to 4 As shown, the wall thickness of the mounting hole 11 is the same as the wall thickness δ of the shell body 10, that is, the thickness dimension of the extension portion 111 in the first direction D1 is the same as the wall thickness δ of the shell body 10, and the thickness dimension of the necking portion 112 in the first direction D1 is the same as the wall thickness δ of the shell body 10.

[0045] In a preferred embodiment, the wall thickness δ of the shell body 10 is 0.2 mm to 0.8 mm, thereby preventing the shell body 10 from having a too large wall thickness δ, which may lead to a reduction in the capacity of the battery cell, or from having a too small wall thickness δ, which may lead to insufficient structural strength of the mounting hole 11 and fail to ensure a reliable connection between the pressure relief member 20 and the shell body 10.

[0046] In this embodiment, the pressure relief member 20 is welded to the shell body 10, and the welding method can be butt welding or penetration welding. The inner wall of the mounting hole 11 has the same shape as the outer wall of the pressure relief member 20 to ensure the sealing of the battery cell shell. In a preferred embodiment, the mounting hole 11 is formed by stamping, so that the side wall of the shell body 10 is efficiently formed into a step-shaped mounting hole 11, which effectively solves the problem of difficulty in welding thin-walled shells, improves the safety of the battery cell, and does not occupy the space inside the battery cell, and effectively improves the production efficiency of the battery cell.

[0047] Furthermore, if Figure 4 As shown, in this embodiment, the pressure relief member 20 is formed with a limiting portion 21 protruding outward, and the limiting portion 21 is arranged on one side of the inner wall of the necking portion 112. The pressure relief member 20 is welded to the shell body 10 to form a welding portion between the necking portion 112 and the limiting portion 21. The welding portion is a welding mark formed between the connection of the two structures under the welding process; in a preferred embodiment, the weld width of the welding portion in the first direction D1 is evenly divided into the necking portion 112 and the limiting portion 21. For example, the weld width of the welding portion (that is, the weld width of the welding portion in the first direction D1) is Figure 4 When the dimension in the first direction D1 under the viewing angle is 1 mm, the weld width of the welding portion arranged at the limiting portion 21 and the necking portion 112 is 0.5 mm, thereby ensuring that the pressure relief member 20 is welded reliably and firmly connected to the shell body 10.

[0048] In a preferred embodiment, Figure 4 As shown, the dimension D of the limiting portion 21 in the first direction D1 is ≥ 0.5 mm, thereby ensuring the reliability that the welding portion can be evenly divided between the limiting portion 21 and the necking portion 112 , thereby improving the connection strength between the pressure relief member 20 and the shell body 10 .

[0049] In this embodiment, if Figure 1 As shown, the shell body 10 is formed as a rectangular shell structure, and the side wall of the shell body 10 includes two large surfaces 101 opposite to each other and two narrow surfaces 102 opposite to each other. The large surface 101 is adjacent to the two narrow surfaces 102, and the area of ​​the large surface 101 is larger than the narrow surface 102; the mounting hole 11 is arranged on the narrow surface 102, so that the pressure relief member 20 is installed on the narrow surface 102 of the shell body 10, so that when a plurality of battery cells are assembled in series or in parallel into a battery module or a battery pack, the battery cells arranged in an upright state (that is, the two narrow surfaces 102 of the battery cells extend in the horizontal direction respectively) can enable the pressure relief member 20 to be arranged at the bottom of the battery cells, so that when the pressure relief member 20 is opened, the risk of electrolyte spraying can be effectively reduced, thereby ensuring the safety of the battery cells.

[0050] It should be noted that the narrow surface 102 of the housing body 10 is a planar structure extending along the first direction D1 , and the large surface 101 of the housing body 10 is a planar structure extending along the second direction D2 .

[0051] In this embodiment, if Figures 2 to 4 As shown, the extension portion 111 and the necked portion 112 are both formed into a closed annular structure, and the necked portion 112 is arranged at one end of the extension portion 111 away from the shell body 10, that is, the side wall of the shell body 10 with the mounting hole 11 and the necked portion 112 are respectively arranged at both ends in the protruding direction of the extension portion 111, so that the shell body 10, the extension portion 111 and the necked portion 112 form a continuous structure, which is convenient for processing and manufacturing, thereby improving the production efficiency of the battery cell.

[0052] Furthermore, in this embodiment, if Figure 4 As shown, the necked portion 112 extends along the first direction D1 so that the extension direction of the necked portion 112 is parallel to the side wall of the shell body 10 on which the mounting hole 11 is provided, ensuring that the pressure relief member 20 can be tightly abutted against the side wall of the necked portion 112 facing the inside of the shell body 10, thereby supporting and limiting the pressure relief member 20. The extension portion 111 extends along the second direction D2, so that the mounting hole 11 is formed into a step-like structure protruding from the shell body 10.

[0053] It should be noted that the first direction D1 is perpendicular to the second direction D2.

[0054] Furthermore, in a preferred embodiment, Figure 4 As shown, the adjacent two side walls of the shell body 10 are connected by an arc-shaped transition portion 103, so as to avoid stress concentration in the shell body 10; a detection portion 104 is formed on the side wall of the shell body 10 with a mounting hole 11, and the detection portion 104 is arranged between the transition portion 103 and the extension portion 111 for airtightness detection; preferably, the size of the detection portion 104 in the first direction D1 is A, 1mm≤A≤5mm, so as to avoid the size A of the detection portion 104 in the first direction D1 being too small to meet the airtightness detection requirements, thereby causing a hidden danger in product sealing. If the size A of the detection portion 104 in the first direction D1 is too large, the size of the pressure relief component 20 will be reduced accordingly, thereby affecting the thermal runaway performance of the battery cell.

[0055] Furthermore, the adjacent two side walls of the shell body 10 are arranged perpendicular to each other (that is, the large surface 101 and the narrow surface 102 as described above are arranged perpendicular to each other), so that the central angle of the transition portion 103 is 90°; the dimension L1 of the pressure relief member 20 in the first direction D1 is L0-(δ+R+A+C+0.5)×2, in mm, wherein L0 is the dimension of the shell body 10 in the first direction D1, in mm, δ is the wall thickness of the shell body 10, R is the radius of the inner wall of the transition portion 103, in mm, and C is the gap between the pressure relief member 20 and the extension portion 111, and the gap is 0.1mm≤C≤0.5mm. If the gap is too small, the assembly of the pressure relief member 20 is affected. If the gap is too large, the contact area between the pressure relief member 20 and the necking portion 112 is too small, and poor welding is likely to occur, thereby sealing and fixing the special-shaped pressure relief member 20.

[0056] Furthermore, in this embodiment, if Figure 4 As shown, the dimension of the necked portion 112 in the first direction D1 is B≥δ+C+0.5, where B≥1.1 mm, so as to ensure that the welding portion has a sufficient setting area, thereby ensuring that the pressure relief member 20 is firmly connected to the shell body 10.

[0057] It should be noted that the battery cell shell structure of the present application can be applied to battery cells with thin-wall shells, rear-wall shells or shells of unequal wall thicknesses.

[0058] In addition, in this embodiment, Figure 1 As shown, the number of the pressure relief member 20 is at least one. When a plurality of pressure relief members 20 are provided, the plurality of pressure relief members 20 may be arranged at intervals on the housing body 10 .

[0059] According to a battery cell shell provided by the utility model, the mounting hole provided in the shell body has an extension portion protruding outward and a necking portion extending inward from the inner wall of the extension portion, so that the mounting hole is formed into a step-like structure; the pressure relief member is embedded in the mounting hole and abuts against the side of the necking portion facing the inside of the shell body, so that the extension portion and the necking portion surround an area for installing the pressure relief member, so that the pressure relief member is installed on the step surface of the inner wall of the mounting hole, so that the necking portion has the functions of fixing and sealing the shell at the same time, thereby realizing the assembly of the pressure relief member and the shell body without changing the thickness of the shell body. In addition, since the mounting hole is formed into a step-like structure and protrudes from the side wall of the shell body where the mounting hole is provided, the pressure relief member embedded in the mounting hole will not interfere with the components inside the battery cell, avoiding the situation where the pressure relief member is scratched internally, thereby reducing the risk of battery cell failure.

[0060] A battery cell provided according to the second aspect of the utility model includes the above-mentioned battery cell shell, and the battery cell shell realizes the assembly of the pressure relief part and the shell body without changing the thickness of the shell body, thereby avoiding the problem of reduced capacity and increased weight of the battery cell due to increased shell thickness, thereby improving the yield rate and production efficiency of the battery cell; in addition, the battery cell shell that integrates the shell body and the pressure relief part can set the pressure relief part toward the bottom, and can also improve the overall safety of the battery cell.

[0061] 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 casing, characterized in that: The battery cell housing comprises: The shell body is provided with a mounting hole, wherein the mounting hole has an extension portion protruding toward the outside of the shell body and a constricted portion extending from the inner wall of the extension portion toward the inside of the mounting hole, so that the mounting hole is formed into a step-like structure; The pressure relief member is embedded in the mounting hole, and the pressure relief member abuts against a side of the neck portion facing the interior of the shell body.

2. The battery cell casing according to claim 1, characterized in that: The housing body is formed into a rectangular housing structure, and the side wall of the housing body includes two large faces opposite to each other and two narrow faces opposite to each other, and the large face is arranged adjacent to the two narrow faces; The mounting hole is arranged on the narrow surface.

3. The battery cell casing according to claim 1, characterized in that: The extension portion and the necking portion are both formed into a closed annular structure, and the necking portion is arranged at one end of the extension portion away from the shell body; And / or, the necked portion extends along a first direction, the extending portion extends along a second direction, and the first direction is perpendicular to the second direction.

4. The battery cell casing according to claim 1, characterized in that: The wall thickness of the mounting hole is the same as the wall thickness of the housing body.

5. The battery cell casing according to claim 1, characterized in that: The adjacent two side walls of the shell body are connected by an arc-shaped transition portion; A detection portion is formed on the side wall of the shell body where the mounting hole is opened. The detection portion is arranged between the transition portion and the extension portion. The size of the detection portion in the first direction is A, 1mm≤A≤5mm.

6. The battery cell casing according to claim 5, characterized in that: The adjacent two side walls of the shell body are arranged perpendicular to each other, and the central angle of the transition portion is 90°; The dimension of the pressure relief component in the first direction is L1=L0-(δ+R+A+C+0.5)×2, wherein L0 is the dimension of the shell body in the first direction; δ is the wall thickness of the shell body, δ=0.2mm~0.8mm; R is the radius of the inner wall of the transition portion; C is the gap between the pressure relief component and the extension portion, 0.1mm≤C≤0.5mm.

7. The battery cell casing according to claim 6, characterized in that: The dimension of the necked portion in the first direction is B≥δ+C+0.5, B≥1.1 mm.

8. The battery cell casing according to claim 1, characterized in that: The mounting hole is formed by punching.

9. The battery cell casing according to claim 1, characterized in that: The pressure relief member is formed with a limiting portion protruding outward, the limiting portion is arranged on one side of the inner wall of the necking portion, the pressure relief member is welded to the shell body to form a welding portion between the necking portion and the limiting portion, and the weld width of the welding portion in the first direction is evenly divided between the necking portion and the limiting portion; The dimension D of the limiting portion in the first direction is ≥0.5 mm.

10. A battery cell, characterized in that: The invention comprises a battery cell casing as described in any one of claims 1 to 9.

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