SE2251551A1

SE2251551A1 - A gasket for a cylindrical secondary cell

Info

Publication number: SE2251551A1
Application number: SE2251551A
Authority: SE
Inventors: Koki Inoue; Saurabh Bidari
Original assignee: Northvolt Ab
Priority date: 2022-12-22
Filing date: 2022-12-22
Publication date: 2024-06-23

Abstract

This disclosure presents a gasket (40) for a cylindrical secondary cell (100), the gasket (40) being configured to be arranged between a cylindrical enclosure (110) and a terminal assembly (1, 10) of the cylindrical secondary cell (100), the gasket (40) comprising a circumferential contact surface (44) comprising an axially extending portion (41) and a radially extending portion (43), the circumferential contact surface (44) being configured to wrap around the terminal assembly (1, 10), wherein the circumferential contact surface (44) comprises a contact section (45) that is chamfered in relation to a longitudinal axis of the gasket (40), the contact section (45) extending between the axially extending portion (41) and the radially extending portion (43).

Description

TECHNICAL FIELD The present disclosure generally pertains to cylindrical secondary cells, and more particularly to a gasket for a cylindrical secondary cell.

BACKGROUND The rapid development of compact and lightweight portable electronic devices in recent times has created a growing need for compact and high-capacity batteries. In particular, use of cells, such as lithium secondary batteries, is rapidly increasing because they have a high energy density per unit weight, a good operating voltage, and excellent lifespan characteristics. Further, to address climate change there is an increasing demand for rechargeable batteries, e. g. to enable electrification of transportation and to supplement renewable energy.

Lithium-ion secondary batteries, also referred to as lithium-ion secondary cells, produce electric energy by redox reactions occurring when lithium ions are intercalated or deintercalated at positive and negative electrodes. Lithium secondary batteries use a material capable of reversibly intercalating or deintercalating lithium ions as active materials for positive and negative electrodes, and have an organic or polymer electrolyte between the positive electrode and the negative electrode.

Cylindrical lithium-ion secondary cells typically include an electrode assembly wound in a j elly-roll shape, in which a separator is interposed between a negative electrode and a positive electrode. These batteries also include a cylindrical enclosure (or a can housing), the electrode assembly, an electrolyte, and a terminal arrangement sealing one end of the cylindrical enclosure.

A cylindrical secondary battery, or cylindrical secondary cell, is typically configured such that a terminal arrangement is located at the upper end of a cylindrical can, which is open, and the cylindrical secondary battery is herrnetically sealed in the state in which a gasket is interposed between the can and the terminal arrangement. The gasket has a function of securing insulation between the terminal arrangement, which is connected to a positive electrode tab of the electrode assembly, and the can, which is connected to a negative electrode tab of the electrode assembly.

There is a need to improve the sealing effect of the gasket, while simultaneously not jeopardizing the insulation effect.

SUMMARY Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified def1ciencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by providing a gasket for a cylindrical secondary cell, the gasket being configured to be arranged between a cylindrical enclosure and a terminal assembly of the cylindrical secondary cell, the gasket comprising a circumferential contact surface comprising an axially extending portion and a radially extending portion, the circumferential contact surface being configured to wrap around the terminal assembly, wherein the circumferential contact surface comprises a contact section that is chamfered in relation to a longitudinal axis of the gasket, the contact section extending between the axially extending portion and the radially extending portion.

The chamfered contact section securely seals around the terminal assembly. During assembly of the cylindrical secondary cell, the gasket is axially clamped by an enclosure of the cylindrical secondary cell, and the chamfered contact section may utilise the axial sealing force to provide a radial sealing force between the terminal arrangement and the enclosure.

Advantageous embodiments are envisioned in the dependent claims below, and advantages associated with the present disclosure, and additional conceivable features, will become clear from the following description of embodiments and examples.

BRIEF DESCRIPTION OF THE DRAWINGS The embodiments disclosed herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Like reference numerals refer to corresponding parts throughout the drawings, in which Figure l is an isometric view of a gasket for a cylindrical secondary cell, Figure 2 is an enlarged axial cross-section of the area encircled in figure 1, and also illustrates a terminal assembly and a cylindrical enclosure between which the gasket is to seal, Figure 3 is a scheniatic axial cross-section of a first end of a cylindrical secondary cell and discloses a terrninal arrangenient coniprising the gasket of figures 1 and 2, Figure 4 is scheniatic axial cross-section of a second end of the cylindrical secondary cell of figure 3, Figure 5 shows the terrninal arrangenient of figure 3 before conipletion, and Figures 6-10 is an exploded View of the components of the terrninal arrangenient shown in figures 3 and 5, where figure 10 scheniatically illustrates the gasket.

DETAILED DESCRIPTION Enibodinients of the present disclosure will now be described niore fully hereinafter. The invention niay, however, be enibodied in niany different forrns and should not be construed as liniited to the enibodinients set forth herein; rather, these enibodinients are provided by way of example so that this disclosure will be thorough and coniplete, and will fully convey the scope of the invention to those persons skilled in the art.

Figures 1 to 3, 5 and 10 (scheniatic illustration in figure 10) show a gasket 40 for a cylindrical secondary cell 100. The cylindrical secondary cell 100 (hereinafter referred to as cell) is illustrated in the cross-sections of figures 3 and 4. In figures 1, 2, 5 and 10, the gasket 40 is illustrated in an undeforrned shape, i.e. before conipletion of the cell 100. Figure 3 illustrates the gasket 40 at or near conipletion of the cell 100. The gasket 40 is a sealing part and an electrically insulating part. The gasket niay alternatively be referred to as an outer gasket.

As is illustrated in figures 2 and 3, the gasket 40 is configured to be arranged between a cylindrical enclosure 110 and a terrninal assenibly 1, 10 of the cell 100. The terrninal assenibly coniprises a terrninal part 1 and a burst part 10, described in detail below.

The gasket 40 coniprises a circuniferential contact surface 44 coniprising an axially extending portion 41 and a radially extending portion 43. The circuniferential contact surface 44 is configured to wrap around the terrninal assenibly 1, 10, as is best shown in figure 3. The circuniferential contact surface 44 coniprises a contact section 45 that is chanifered in relation to a longitudinal axis A of the gasket 40. The contact section 45 extends between the axially extending portion 41 and the radially extending portion 43, see figure 2. The contact section 45 may be referred to as a chamfered contact section 45.

As is illustrated in figure 2, the axially extending portion 41 of the circumferential contact surface 44 extends essentially in parallel with the longitudinal axis A of the gasket 40. The radially extending portion 43 of the circumferential contact surface 44 extends essentially orthogonal to the longitudinal axis A. The contact section 45 of the circumferential contact surface 44 extends obliquely to the longitudinal axis A. The contact section 45 may extend at an angle of approximately 45 degrees (figure 2) to the longitudinal axis A, a suitable range for the angle being 30 to 60 degrees.

As is shown in figures 1 to 3 and 5, the contact section 45, or chamfered contact section, is at least partly arranged axially proximally of the terrninal assembly 1, 10. In other words, the contact section 45 is at least partly arranged axially intemally the terrninal assembly 1, 10. As is clear from e.g. figures 2 and 3 in conjuction, the contact section 45 is positioned on the electrode roll-side (the electrode roll described below) of the terrninal assembly 1, 10.

As mentioned, the circumferential contact surface 44 is configured to wrap around the terrninal assembly 1, 10. In detail, referring to figures 2 and 3 in conjunction, the circumferential contact surface 44 extends from an axially proximal side of the terrninal assembly, along an axially proximal end surface of the terrninal assembly, along a radially outer edge of the terrninal assembly and to and along an axially distal end surface of the terrninal assembly 1, 10. The chamfered contact section 45 is arranged at the axially proximal end of the outer edge of the terrninal assembly.

In the example of figure 2, the thickness to of the gasket 40 at the chamfered contact section 45 exceeds the thickness of the gasket 40 at the axially extending portion 41. As is also illustrated, the thickness to of the gasket 40 at the chamfered contact section 45 exceeds the thickness of the gasket 40 at the radially extending portion 43.

The thickness to of the gasket 40 at the chamfered contact section 45 is measured from the inner surface of the chamfered contact section 45 and normal thereto across the gasket 40. In other words, the thickness to of the gasket 40 at the chamfered contact section 45 is measured 4 obliquely through the gasket 40 sidewall. The thickness of the gasket 40 at the axially extending portion 41 is measured radially through the gasket sidewall and the thickness of the gasket 40 at the radially extending portion 43 is measured axially through the gasket sidewall. Thus, in all cases the thickness is measures orthogonal to the respective inner surfaces of the gasket 40.

In figure 2, the dotted lines in the vicinity of the chamfered contact section 45 illustrate how the gasket, and its circumferential contact surface 44, would be shaped without the chamfered contact section 45. Such a gasket essentially has the shape of the only very schematically illustrated gasket in figure 10, where the chamfered contact section 45 is not shown. As is illustrated, without the chamfered contact section the transition between the axially extending portion 41 and the radially extending portion 43 would be a relatively sharp comer. Such a comer, even if slightly rounded, would not provide a satisfactory local seal against the terminal assembly 1, 10, more precisely against the burst part 10. By local seal is meant locally between the comer and the burst part 10.

In prior art gaskets for cylindrical secondary cells, a sealing between a cylindrical enclosure and a terminal assembly (or a similar component) may typically chieﬂy be obtained by the gasket being clamped axially by the cylindrical enclosure. In other words, the gasket is clamped at both its axial sides, i.e. from the top and from the bottom of the cell. Thus, the gasket undergoes a deformation in the axial direction on an axially proximal end and on an axially distal end of the terminal assembly. The deformation of prior art gaskets (and the provided sealing effect) may be said to occur chiefly, or even entirely, in the axial direction.

Now, by the provision of the chamfered contact section 45, the current gasket 40 in addition provides a radial sealing force (and sealing effect) between the terminal arrangement and the enclosure. As is apprehended from figures 2 and 3 in conjunction, as the gasket 40 is compressed axially by the cylindrical enclosure 110, the chamfered contact section 45 will be radially compressed and provide a radial sealing between the terminal assembly 1, 10 and the circumferential contact surface 44. More precisely, the radial sealing occurs between the chamfered contact section 45 and the burst part 10 of the terminal assembly.

Referring again to figure 2, the chamfered contact section 45, as seen in an axial cross-section, may be substantially straight. Such as chamfered contact section 45 may provide for a tight seal when radially forced against the burst part 10 of the terminal assembly 1, 10. Said burst part 10 may, as is shown, comprise a circumferential edge, which may be rounded. After assembly, the chamfered contact section 45 may, as shown, be arranged at the axially proximal end (here, lower end) of the outer edge of the terminal assembly 1, 10.

As is illustrated, the axially distal (here, upper) end of the gasket 40 is folded radially inwards as the gasket sidewall, and its circumferential contact surface 44, is wrapped around the terminal assembly 1, 10. Since the axially distal end of the gasket 40 is folded in such a manner, the gasket 40 may provide for not only an axial sealing but also a radial sealing at the axially distal end. When the axially distal end of the gasket 40 is folded, it may be brought into tight contact with at least a (upper) portion of the radially outer edge of the terminal assembly and the axially distal end surface of the terminal assembly 1, 10.

As is illustrated in figures 1 and 2, the axially distal end of the gasket 40 may comprise a circumferential bulge 46 or protrusion that may locally improve the axial sealing and also the radial sealing. The circumferential bulge 46 protrudes radially inward from the axially extending portion 41. The distal end of the gasket 40 may be tapered (see figure 2), which may avoid or reduce undulations or wrinkles being formed after the gasket 40 has folded radially inwards to wrap the terminal assembly 1, 10.

The gasket 40 may be made of a polymer material, such as a therrnoplastic material. The therrnoplastic material may be PBT (polybutylene terephthalate) or PFA (perﬂuoroalkoxy alkane).

Figures 3, 5 and 6 show the terminal part 1. As is particularly clear from figure 6, the terminal part 1 may comprise a central portion 2, an outer portion 3, and a vent portion 4 arranged between the central portion 2 and the outer portion 3. These radially separate portions 2, 3, 4 of the terminal part 1 may be concentric, as illustrated.

The central portion 2 may form a terminal of the cell 100 once assembled, see figure 3. By terminal is herein meant that equipment that is powered by the cell 100 and electrically charges the cell 100 may be connected thereto via the terminal. Electrical connection to the terminal may be established by a connector (not shown) being brought in electrical contact with the terminal. Such a connector may be welded to the terminal, i.e. to the central portion 2. To facilitate establishing the connection, e.g. an automated connection, it may be advantageous 6 that the central portion 2 is positioned centrally on the terminal part 1. As is shown, the central portion 2 may be essentially circular.

The outer portion 3 may be annular and radially surround the central portion 2. As is particularly clear from figure 3, the outer portion 3 may, after assembly, be electrically connected to an electrode 101 of the cylindrical secondary cell 100. As will be described, the outer portion 3 may be electrically connected to the electrode 101 via other components of a terminal arrangement 50 of the cylindrical secondary cell 100.

The Vent portion 4 may be annular, may be radially surrounded by the outer portion 3, and may radially surround the central portion 2, see figure 6. The Vent portion 4 comprises a number of Vent holes 5 for release of gas and/or other ej ecta through the terminal part 1.

It is noted that figures 3 and 5 illustrate sharp angles between for example the central portion 2 and the Vent portion 4 of the terminal part 1, but in an actual implementation these transitions are typically smooth, as shown in figure 6.

A first (top) end of the cylindrical secondary cell 100 is illustrated in figure 3 and a second (bottom) end of the cell 100 is illustrated in figure 4. The cell 100 may be of a so-called 2170- type (radius 21 millimeters and height 70 millimeters). As is shown, the cell 100 may comprise a cylindrical enclosure in the form of a can 110 within which an electrode roll 103 and the terminal arrangement 50 are arranged.

The burst part 10, see especially figure 7, may comprise a Vent groove (also referred to as a notch) 11 configured to provide an opening in the burst part 10 if a pressure to which the burst part 10 is subjected reaches a second threshold Value. As is shown in figures 3 and 5, the burst part 10 is positioned intemally with respect to the terminal part 1.

The burst part 10 may essentially have the shape of a bowl, or circular cylinder with one open end and one closed end. In other words, the burst part 10 may comprise a circular disc portion 12 (bowl bottom or closed cylinder end) and a ﬂange portion 13 (bowl or cylinder lateral sidewall), see figure 7. The disc portion 12 may be convex, such that is protrudes downward in the axial direction away from to the ﬂange portion 13, see figure 5.

Referring again to figure 5, the terminal arrangement 50 may further comprise a current interruption device 30, which may altematively be referred to as a current collector disc. The current interruption device 30, illustrated in figure 9, may comprise a central contact portion 31 and a radially separate collecting portion 33. These portions 31, 33 of the current interruption device 30 may be concentric, as is illustrated.

A groove (or notch) 32 may at least partly surround the contact portion 31, such that the contact portion 31 may be separated from the collecting portion 33 by the groove 32 rupturing, in the event that a pressure to which the burst part 10 is subj ected reaches a first threshold value. The central contact portion 31 is secured to the center of the burst part 10, e.g. by welding.

The in the present embodiment annular collecting portion 33 may be electrically connected to the electrode 101 of the cylindrical secondary cell 100. For example, as is schematically illustrated in figure 3, a conductor 104 in the form of a so-called tab may extend from the electrode 101 to the annular collecting portion 33 of the current interruption device 30.

As is shown, the annular collecting portion 33 may comprise a number of ﬂow holes 35 for release of ej ecta through the current interruption device 30. The ﬂow holes 35 of the annular collecting portion 33 may be similar in shape (essentially bean-shaped) and size to the vent holes 5 of the terminal part, at least in a plan view.

Referring in particular to figures 5 and 8, the terminal arrangement 50 may further comprise a schematically illustrated insulator part 20 that is arranged between the annular collecting portion 33 of the current interruption device 30 and the burst part 10. The insulator part 20 is electrically insulating, and may altematively be referred to as an inner gasket as it is arranged radially intemally the outer gasket 40.

The electrode roll 103 may comprise a first 101 and a second 102 electrode, optionally with a separator sheet arranged between them, that are formed into a roll in a manner known per se. Such an electrode roll 103 is often referred to as a jelly-roll. The first electrode 101 may, as illustrated, be electrically connected to the terminal part 1 and the second electrode 102 may be electrically connected to the can 110. The electrodes 101, 102 may be referred to as electrode assemblies. The can 110 may comprise a bottom formed in one piece with the sidewall (figure 4), or the can bottom may be closed by a separate lid (not shown). 8 The order, or relative positions, of the components of the cell 100 is clear from figures 3, 5 and 6 to 10. Starting from the top (as illustrated, i.e. most downstream as seen in the ej ecta ﬂow direction), the terminal part 1 forms the upperrnost part of the cell 100. The radially outer edge of the terminal part 1 is enclosed by the axial ﬂange 13 of the burst part 10, which ﬂange 13 is bent radially inwards during manufacture. Thus, the terminal part 1 may be attached to, or held by, the burst part 10. The burst part 10 is positioned below the terminal part 1, i.e. intemally with respect to the terminal part 1 after assembly.

In some detail, during manufacture the first end of the cylindrical enclosure 110, also referred to as the can, may be folded to form an end ﬂange 112 (see figure 3). As the end ﬂange 112 is formed, the axially distal end of the gasket 40 is forced radially inwards towards the inwards bent axial ﬂange 13 of the burst part 10. Thus, the forrning of the end flange 112 may deforrn the gasket 40, close the first end of the cylindrical enclosure 110 by fixing the burst part 10 thereto, and also seal the seal first end of the cylindrical enclosure 110.

Typically before the end ﬂange 112 is formed, a circumferential groove 111 has been formed in the cylindrical enclosure 110. The circumferential groove 111 may be formed by beading. The circumferential groove 111 protrudes radially inward into the cell 100. The gasket 40 may be axially clamped between the circumferential groove 111 and the end ﬂange 112.

The end flange 112 and the circumferential groove 111 may be located at the first end of the cylindrical enclosure 110, in a first end zone 120. The gasket 40 may thus be axially clamped between the circumferential groove 111 and the end ﬂange 112, within the first end zone 120.

The gasket 40 may essentially have the shape of a stepped, open circular cylinder. The gasket 40 may comprise a first (upper) section formed by the axially extending portion 41 of larger diameter and a second (lower) section 42 of smaller diameter. A step formed by the radially extending portion 43, shaped as an annular disc, may extend between the axially extending portion 41 and the second section 42. The second section 42 may be formed by a second axially extending portion.

The diameter of the first (larger) section 41 of the gasket 40 may essentially correspond to the diameters of the terminal part 1 and the burst part 10. The diameter of the second (smaller) section 42 may essentially correspond to the diameters of the insulator part 20 and the current interruption device 30, see figures 3 and 5.

The insulator part 20 is positioned below the burst part 10 to electrically insulate the burst part 10 from the current interruption device 30. The current interruption device 30 is positioned below the insulator part 20.

In the depicted embodiment, the terrninal part 1 and the burst part 10 (the terrninal assembly) are positioned radially within the first section 41 of the gasket 40 whereas the insulator part 20 and the current interruption device 30 are positioned radially within the second section 42 of the gasket 40.

As is illustrated in figure 3, during manufacture an open can end (lateral sidewall) may be deforrned such that, after completion, the terrninal arrangement 50 is held in place. The terrninal arrangement 50 may be clamped to the can 110 by the deformation of the open can end. Thereby, the terrninal arrangement 50 may seal the open end of the can 110. Thus, the terrninal arrangement 50 may serve the purposes of sealing the cell 100, providing a (typically positive) terrninal, and also provide a vent function.

Thus, upon deformation of the can 110, the gasket 40 is also deforrned. As is apprehended from figures 3 and 5, after the deformation of the can 110 (figure 3), the first section 41 of the gasket 40, the terrninal part 1 and the burst part 10 are clamped axially together by the can 110. It is to be noted that the components are illustrated at some distance from one another in figures 3 and 5. In a real implementation, the deformation of the can 110 continues beyond the illustration of figure 3, until the can 110 tightly clamps the terrninal arrangement 50 and the cell 100 is sealed.

Should the pressure inside the cell 100 increase, e. g. as a result of an intemal cell malfunction or an extemal load short-circuit, the pressure will deforrn the burst part 10 such that its central portion moves (upward) in a direction away from the current interruption device 30 (axially away from the electrode roll 103). Since the contact portion 31 of current interruption device 30 is secured to the burst part 10, the contact portion 31 will move axially along with the burst part 10. As is shown e.g. in figure 3, before burst part 10 deformation the disc portion 12 of the burst part 10 and the contact portion 31 of the current interruption device 30 protrude axially toward each other.

After a certain pressure increase, at a first threshold value, the groove 32 of the current interruption device 30 will break such that the collecting portion 33 is separated from the contact portion 31. As a result, the electrode 101 is electrically disconnected from the terrninal part 1. When the burst part 10 is deforrned axially toward the upper cell end 100 such that the groove 32 of the current interruption device 30 will break, the burst part 10 may change shape from being convex to being concave, such that it protrudes (upward) in the axial direction along with the ﬂange portion 13. In some cases, the pressure increase will now stop.

In case the pressure inside the cell 100 increases beyond the first threshold value to a second, higher, threshold value the vent groove 11 of the burst part 10 will break such that the overpressure may be released through the burst part 10. More in detail, the overpressure (ej ecta) will be released (ﬂow) through the ﬂow holes 35 of the current interruption device 30, through the opening formed in the burst part 10 and finally exit the cell 100 through the vent holes 5 of the terminal part 1. An additional ﬂow path may be formed through the central opening of the current interruption device 30 formed by the ruptured groove 32.

Modifications and other variants of the described embodiments will come to mind to ones skilled in the art having benefit of the teachings presented in the foregoing description and associated drawings. Therefore, it is to be understood that the embodiments are not limited to the speciﬁc example embodiments described in this disclosure and that modifications and other variants are intended to be included within the scope of this disclosure.

Furthermore, although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Therefore, persons skilled in the art would recognize numerous variations to the described embodiments that would still fall within the scope of the appended claims. As used herein, the terms "comprise/comprises" or "include/includes" do not exclude the presence of other elements or steps. Furthermore, although individual features may be included in different claims (or embodiments), these may possibly advantageously be combined, and the inclusion of different claims (or embodiments) does not imply that a certain combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. Finally, reference numerals in the 11 clairns are provided rnerely as a clarifying example and should not be construed as lirniting the scope of the clairns in any Way.

Claims

1.Claims A gasket (40) for a cylindrical secondary cell (100), the gasket (40) being configured to be arranged between a cylindrical enclosure (110) and a terminal assembly (1, 10) of the cylindrical secondary cell (100), the gasket (40) comprising a circumferential contact surface (44) comprising an axially extending portion (41) and a radially extending portion (43), the circumferential contact surface (44) being conf1gured to Wrap around the terrninal assembly (1 , 10), Wherein the circumferential contact surface (44) comprises a contact section (45) that is chamfered in relation to a longitudinal axis (A) of the gasket (40), the contact section (45) extending between the axially extending portion (41) and the radially extending portion (43). The gasket (40) of claim 1, Wherein the contact section (45) is conf1gured to be at least partly arranged axially proximally of the terrninal assembly (1 , 10). The gasket (40) of claim 1 or 2, Wherein the circumferential contact surface (44) is conf1gured to Wrap around the terrninal assembly (1, 10) such that it extends from an axially proximal side of the terrninal assembly (1, 10), along an axially proximal end surface of the terrninal assembly (1, 10), along an outer edge of the terrninal assembly (1, 10) and to and along an axially distal end surface of the terrninal assembly (1, 10), Wherein the chamfered contact section (45) is arranged at the axially proximal end of the outer edge of the terrninal assembly (1, 10). The gasket (40) of claim 3, Wherein the thickness (to) of the gasket (40) at the chamfered contact section (45) exceeds the thickness of the gasket (40) at the axially extending portion (41). The gasket (40) of claim 3 or 4, Wherein the thickness (to) of the gasket (40) at the chamfered contact section (45) exceeds the thickness of the gasket (40) at the radially extending portion (44). The gasket (40) of any preceding claim, Wherein the chamfered contact section (45), as seen in an axial cross-section, is substantially straight. The gasket (40) of any preceding claims, Wherein the gasket (40) is made of a therrnoplastic material. The gasket (40) of claim 7, Wherein the therrnoplastic material is PBT (polybutylene terephthalate) or PFA (perﬂuoroalkoxy alkane). A terminal arrangement (50) for a cylindrical secondary cell (100), the terminal arrangement (50) comprising - a terminal part (1), a burst part (10) positioned intemally With respect to the terminal part (1) and comprising a vent groove (11) configured to provide an opening in the burst part (10) if a pressure to Which the burst part (10) is subjected reaches a second threshold value, and - a gasket (40) of any preceding claim. The terminal assembly (5 0) of claim 9, Wherein the burst part (10) laterally Wraps around the terminal part (1) and the gasket (40) laterally Wraps around the burst part (10). The terminal assembly (50) of claim 9 or 10, Wherein the terminal part (1) comprises a central portion (2) forrning a terminal of the cylindrical secondary cell (100), an annular outer portion (3) for electrical connection to an electrode (110) of the cylindrical secondary cell (100), and an annular vent portion (4) arranged between the central portion (2) and the annular outer portion (3), the annular vent portion (4) comprising at least one vent hole (5) for release of gas and/or other ej ecta through the terminal part (1). A cylindrical secondary cell (100), comprising - a cylindrical enclosure (110) comprising a cylindrical sideWall extending along a longitudinal axis between a second end and a first open end and defining an inner volume therein surrounded by the cylindrical sideWall, - an electrode assembly (101) positioned in the inner volume of the cylindrical enclosure (110), - a terminal assembly (1, 10) mounted at the open end of the cylindrical enclosure (110), and - a gasket (40) according to any one of claini 1 to The cylindrical secondary cell (100) of claini 12, Wherein the cylindrical enclosure (110) coniprises a circuniferential groove (111) at the first end zone (120), Wherein the gasket (40) abuts against the circuniferential groove (111). The cylindrical secondary cell (100) of claini 13, Wherein the first end of the cylindrical enclosure (110) is folded to forrn an end ﬂange (112), Wherein the gasket (40) is axially claniped between the circuniferential groove (111) and the end flange (112). The cylindrical secondary cell (100) of clain1 14, Wherein the chan1fered contact section (45) of the gasket (40) is radially sealingly forced against the terrninal assembly (1, 10) by the gasket (40) being axially claniped between the circuniferential groove (111) and the end flange (112).