WO2023247653A1

WO2023247653A1 - Wrapping for a cell in a potted battery module

Info

Publication number: WO2023247653A1
Application number: PCT/EP2023/066872
Authority: WO
Inventors: Eduard MARTI BIGORRA; Tetsuya Makino; Love FÄLTSTRÖM
Original assignee: Northvolt Ab; Northvolt Revolt Ab; Northvolt Systems Ab
Priority date: 2022-06-22
Filing date: 2023-06-21
Publication date: 2023-12-28
Also published as: SE2250769A1

Abstract

Disclosed herein is a potted battery assembly (200, 500, 600) comprising a cell (14) housed in a wrapping (20) to thereby form a wrapped cell (21) and a potting compound (15) arranged to bond the wrapped cell (21) into the battery assembly (200, 500, 600). The wrapping (20) comprises a first portion (22) bonded to the potting compound (15), and an openable portion (24) configured to open to thereby permit removal of the cell (14) from the wrapping (20), such that the cell may be readily removed from the potted battery assembly (200, 500, 600), for example during a process (800) of disassembly thereof.

Description

WRAPPING FOR A CELL IN A POTTED BATTERY MODULE

Technical Field

The present disclosure relates to battery assemblies. In particular, the present disclosure relates to a potted battery assembly, and methods for assembly and disassembly thereof.

Background

Rechargeable or secondary batteries (cells) find widespread use as electrical power supplies and energy storage systems. For example, in automobiles, battery assemblies (e.g. battery packs or battery modules) may include a plurality of electrochemical cells, provided as a means of effective storage and utilization of electric power.

Potting is the process of partially or completely filling a space around cells (e.g. in a frame) or embedding cells (e.g. without a frame) with a compound, for the purpose of providing resistance to shock and vibration, as well as creating a seal against moisture, solvents, and corrosive agents. Potting compounds may also aid with electrical insulation, flame retardancy, and/or heat dissipation. Battery assemblies may form a structural unit only using the cells themselves and a potting compound that bonds the cells into place, such that a frame is not required.

In order to reduce the environmental impact of the production and disposal of battery assemblies, it is desirable to find ways of reusing or recycling components thereof. In order to assist in such reuse or recycling, it may be desirable to make battery assemblies easier to disassemble.

However, despite the advantages of potting, recycling processes for such battery assemblies may be hindered by the presence of the potting compound, which may make battery assemblies less easy to disassemble. Summary

It is realized as part of the present disclosure that the advantages of potting may be realized in a potted battery assembly without complicating a disassembly of such a potted battery assembly.

In particular, according to an aspect of the present disclosure, there is provided a cell housed in a wrapping to thereby form a wrapped cell, and a potting compound arranged to bond the wrapped cell into the battery assembly.

As used herein, a ‘wrapping’ may entirely or substantially enclose the cell in such a way that the cell is retained therein. It will be understood that the wrapping may have through-holes to allow for electrical connections, ventilation (e.g. in the event of failure), etc.

Furthermore, as used herein, to ‘bond’ the wrapped cell into the battery assembly may refer to a fixing of the wrapped cell into place, e.g. into a (relative) location intended for the wrapped cell in the battery assembly, under action of the addition of the potting compound. The potting compound may be adhesive, e.g. a glue, that may be introduced uncured/unset and then allowed to cure/set such that wrapped cells may become stuck in place.

For example, a battery assembly may be assembled by arranging at least one wrapped cell in an intended position in the battery assembly, and fixing said at least one wrapped cell at the intended position at least by bonding the potting compound to the first portion of the wrapping. This may be repeated for any other cells to be included in the battery assembly, or may be performed for a plurality of wrapped cells at the same time.

The wrapping may advantageously comprise a first portion that is bonded to the potting compound, and an openable portion configured to open to thereby permit removal of the cell from the wrapping.

That is, the wrapped cell may be held in place by the potting compound via the bonding thereof to the first portion. However, another portion of the wrapping, i.e. , different to the first portion, may then protrude, extend from, be exposed, etc. in respect of the surrounding potting compound. Thus, a portion of the wrapping that is not bonded to the potting compound may be provided with an openable portion that allows for the cell to be removed from the wrapping.

It will be appreciated that, in order to permit removal of the cell from the wrapping, the cell may not be strongly bonded to an inside of the wrapping.

Indeed, in some examples, an inner surface of the wrapping and/or an outer surface of the cell may be configured to permit removal of the cell from the wrapping. For example, a relatively weak adhesive, compared to the bonding strength of the potting compound, may be provided between the inner surface of the wrapping and the outer surface of the cell, such that the cell is only weakly held in the wrapping and thus may be readily removeable therefrom.

A battery assembly may be disassembled by opening the openable portion of a wrapped cell to thereby permit removal of the cell from the wrapping, and removing the cell from the wrapping. The cell may then be advantageously recycled/reused separately from a recycling process for the potting compound. In some preferred examples, a plurality of wrapped cells may be provided in a battery assembly, and a process for opening all of the openable portions of the wrappings simultaneously may be performed.

The openable portion of the wrapping may take any suitable form for providing a guided, controlled, and/or localized opening of the wrapping, thereby allowing for a predictable opening of the wrapping and hence facilitating an automation (or faster manual performance) of the opening.

In some examples, the openable portion may comprise a structural weakening, such as a perforation, a pre-folding, or the like. Thus, the openable portion may be opened by pulling (tearing, ripping, etc.) the wrapping until the openable portion opens at the location of the structural weakening.

During normal operations of the cell, i.e., during charging and discharging, the cell may swell and shrink, which may cause structural stresses on the wrapping, such that the wrapping may risk tearing open at the structural weakening. Therefore, in some examples, the structural weakening may be arranged to accommodate such structural stresses during normal operations of the cell. For example, the swelling may be confined to one plane or axis of the cell (e.g., for a cylindrical cell, the radial direction), and the structural weakening may thus be arranged perpendicular or otherwise away from this plane or axis.

It will be appreciated that the structural weakening may additionally or alternatively be calibrated in respect of the weakening such that the openable portion is sufficiently weakened to open upon a pulling action, without being so weak as to open during normal operations of the cell.

In some examples, the openable portion may be configured to open upon application of a chemical process. For example, the openable portion may be impregnated with or formed of a soluble or otherwise reactive material that causes the openable portion to open when a solvent or other reactant is applied thereto. The openable portion may instead comprise a material having a different melting point than the surrounding material such that the openable portion may be, e.g., melted away to thereby open.

Such examples may be combined with a structural weakening, but in other examples, the openable portion may only be configured to be opened using a chemical process. Thus, no structurally weaker point in the wrapping may exist before application of the chemical process, thus improving the stability and strength of the wrapping (and thus the battery assembly as a whole).

Depending on the implementation, the openable portion may be one or more separate or intersecting lines, e.g., arranged like seam(s), such that the wrapping may open centrally or at a side, or peel open in sections. In some examples, the wrapping may further comprise a removable portion that is removably attached to the first portion via the openable portion. Thus, by opening the openable portion, the removeable portion may be removed.

By removing the removeable portion, reliable access to the cell may be further improved, which may further improve the ease with which the battery assembly is disassembled. Furthermore, in the event that the openable portion comprising a structural weakening (i.e. , to be torn or pulled open) a wrapping having a removeable portion may only require a single grip location (e.g., on the removeable portion) to enable its removal, thereby simplifying a disassembly process for the potted battery assembly.

The wrapping may further comprise an opening aid configured to facilitate opening of the openable portion. The opening aid may be a tab or flap to allow a human or machine to grip the wrapping in such a way as to enable reliable opening of the opening portion. Additionally or alternatively, the opening aid may be a visual aid indicating the location of the openable portion, e.g., for instructing where to apply a chemical solvent or agent. Thus, the ease with which the battery assembly is disassembled may be further improved.

The disassembly process may take any suitable form for opening the openable portion, and may preferably comprise opening all of the wrappers of the wrapped cells comprised in the battery assembly at a same time.

In an example implementation, the potting compound may be arranged as multiple sections respectively bonded to separate portions of the wrapping. For example, the first portion may be bonded to a first section of the potting compound, and a second portion of the wrapping may be bonded to a second section of the potting compound. The openable portion may then be arranged between the first portion and the second portion.

In such an example implementation, opening the openable portion of the wrapped cell may comprise separating the first section and the second section of the potting compound, thereby causing the openable portion arranged therebetween to open.

The potted battery assembly may further comprise, in some examples, a third section of the potting compound configured to occupy a space between the first section and the second section. The third section may also be configured for a weaker bonding between the third section and the openable portion than the bonding between the first section and the first portion, and the second section and the second portion. For example, the third section may comprise an expanding foam, polystyrene, or some other material that may preferably be configured to allow the openable portion to open (i.e. not being so adhesive as to seal the openable portion in a closed position). The third section may provide a structural filling between the first section and the second section of the potting compound, but may then readily give way during a disassembly process when the first section and the second section are pulled apart or otherwise separated from each other.

According to this example, one of the sections of the potting compound may be gripped or otherwise manipulated by an automated mechanical manipulator and moved apart from the other section in a single motion, which may cause all of the wrappings to be opened at a same time. The cells may then be readily removed (e.g., under the action of gravity), thus allowing for separate disposal (e.g., recycling) of the cells and the potting compound.

In some preferred embodiments, the wrapping may comprise one or more materials selected for compatibility with a recycling process for the potting compound. Accordingly, the potting compound may be processed for recycling with the wrappers (or remaining portions thereof) still bonded thereto.

It will be appreciated that the presently described wrappers may be applied to any shape of cell, such as cylindrical or prismatic, and the battery assembly containing such wrapped cells may be a battery pack, a battery module with or without a frame. That is, the present approach may be readily applied to modular battery packs as well as so-called ‘structural batteries’, which may not only provide energy storage but also mechanical structure.

In any event, numerous advantages, some of which are described above, may be realized through the wrapping of cells in a potted battery assembly with a wrapping having an openable portion. These advantages, as well as others, may be further appreciated through a description of specific illustrated embodiments.

Brief Description of the Drawings One or more embodiments will be described, by way of example only, and with reference to the following figures, in which:

Figure 1 schematically shows an example prior art potted battery assembly;

Figure 2 schematically shows an example potted battery assembly according to an embodiment of the present disclosure;

Figure 3 shows an enlarged view of a wrapped cell, according to an embodiment of the present disclosure;

Figures 4A and 4B show example forms for wrappers for housing cylindrical and prismatic cells, respectively;

Figures 5A and 5B schematically show an example method for disassembling a potted battery assembly, according to an embodiment of the present disclosure wherein a wrapper comprises a removeable portion;

Figures 6A and 6B schematically show another example method for disassembling a potted battery assembly, according to an embodiment of the present disclosure wherein the potting compound is formed of multiple sections bonded to respective portions of a wrapper;

Figure 7 illustrates a method for assembling a potted battery assembly, according to an embodiment of the present disclosure; and

Figure 8 illustrates a method for disassembling a potted battery assembly, according to an embodiment of the present disclosure.

Detailed Description

The present disclosure is described in the following by way of a number of illustrative examples. It will be appreciated that these examples are provided for illustration and explanation only and are not intended to be limiting on the scope of the disclosure.

Furthermore, although the examples may be presented in the form of individual embodiments, it will be recognized that the present disclosure also covers combinations of the embodiments described herein.

Figure 1 schematically shows a cross-sectional view of an example prior art potted battery assembly 1 , having a casing 2 containing a plurality of cells 3. The cells 3 may be prismatic and arranged in a stack, as illustrated, but it will be appreciated that the cells 3 may instead be cylindrical or have another form or arrangement within the casing 2.

Each cell 3 may have one or more electrodes 4 (e.g. an anode and a cathode connector) for electrically (inter)connecting the cells 3, e.g., via an electrical connector 5 for the potted battery assembly 1 , which may comprise busbars, wires, or some other electrical connection means.

The cells 3 may be charged with electrical energy, i.e. , via the electrical connector 5, and configured to store said electrical energy for later discharge. For example, the potted battery assembly 1 may be included in an electric vehicle.

The potted battery assembly 1 may further comprise a potting compound 6 such that the cells 3 are embedded therein. The potting compound 6 may provide a resistance against shocks or impacts, as well as an accommodation for swelling of the cells 3 during normal operations (i.e., charge and discharge of the cells 3), to name but a few functions of the potting compound 6.

The potting compound 6 may bond directly to the outer casings of the cells 3, or to a coating bonded thereto, such that the cells 3 are resil iently held in place in the potted battery assembly 1 .

According to such a prior art arrangement, if and when it is desired to disassemble the potted battery assembly 1 , the direct bonding of the potting compound 6 to the cells 3 may complicate a removal of the cells 3 from the potted battery assembly 1 . Therefore, it may be cost and energy inefficient to recycle such a potted battery assembly 1 .

Figure 2 schematically shows a cross-sectional view of an adapted potted battery assembly 200, according to an embodiment of the present disclosure, which improves the ease of disassembly and thus the cost and efficiency of recycling the potted battery assembly 200, among other advantages which will be apparent from the following discussion.

The potted battery assembly 200 may comprise a casing 12 containing a plurality of cells 14, having electrodes 16 interconnected via an electrical connector 18 such that the cells 14 can be collectively charged and discharged.

The casing 12 may be partially (or almost entirely) filled with a potting compound 15 so as to substantially surround and embed the cells 14. For example, the cells 14 may be placed at their intended positions whilst the potting compound 15 is introduced in a liquid form, such that the potting compound 15 can flow freely into the free space(s) in the casing 12 and around the cells 14. The potting compound 12 may then be allowed to harden (e.g., set, cure, etc.), thereby fixing the cells 14 into place.

The potting compound 15 may comprise polyurethane, acrylic, epoxy resin, silicone, or some other suitable material, or some combination thereof. The particular choice of material(s) for the potting compound 15 may depend on the anticipated environment in which the potted battery assembly 200 shall be installed, the desired material physical properties, processing needs, etc. It will be understood that the potting compound 15 may have adhesive properties so as to fixedly embed cells 14 in place in the potted battery assembly 20.

According to the illustrated embodiment, and in contrast to the prior art potted battery assembly 1 discussed above, the potting compound 15 may not bond directly to the cells 14 but instead to a wrapping 20 placed therearound. That is, the plurality of cells 14 may be housed in respective wrappings 20 to thereby form wrapped cells 21 .

As illustrated in figure 2, the wrapping 20 may have a through-hole or opening therein to allow electrical connection of the electrodes 16 to the electrical connector 18. In some examples, the wrapping 20 may itself comprise an intermediate electrically connective portion.

Figure 3 schematically shows an enlarged portion of figure 2, showing a wrapped cell 21 embedded in a potting compound 15. In the illustrated example, the wrapping 20 may comprise a first portion 22 bonded (e.g., adhesively) to the potting compound 15, and an openable portion 24 configured to open to thereby permit removal of the cell 14 from the wrapping 20. As is further illustrated in figure 3, the wrapping 20 may in some examples comprise a removeable portion 26 removably attached to the first portion 22 via the openable portion 24. The openable portion 24 may comprise a structural weakening such as a perforation such that the removeable portion 26 may be removed by opening the openable portion 24, e.g., by pulling, tearing, etc.

The wrapping 20 may be made of any suitable material, such as paper, plastic, a composite material, or some combination thereof. In some examples, the wrapping 20, including the arrangement of the openable portion 24, may be configured to withstand the structural swelling and shrinking of the cell 14 during normal operations.

The wrapping 20 may further be configured on its inner surface to permit removal of the cell 14 from the wrapping 20. That is, the inner surface of the wrapping 20 and/or the outer surface of the cell 14 may be slideable relative to each other, or fixed using a relatively weak adhesive (compared to the adhesive strength of the potting compound 15).

An example method 700 for assembling a potted battery assembly (such as the one illustrated in figure 2) is illustrated in figure 7. The method 700 may be discussed by reference to the illustrated potted battery assembly 200.

The method 700 may comprise arranging 710 a wrapped cell 21 in an intended position in the battery assembly 200, and fixing the wrapped cell 21 at the intended position at least by bonding the potting compound 15 to the first portion 22 of the wrapping 20.

The method 700 may repeat for any further wrapped cells 21 to be added into the battery assembly 200, or the method 700 may be performed simultaneously for a plurality of wrapped cells 21 , depending on the implementation.

Figures 4A and 4B show various alternative examples for a form for such a wrapping 20. Figure 4A shows example forms for a wrapping 20 for housing a cylindrical cell, whilst figure 4B shows example forms for a wrapping 20 for housing a prismatic cell. It will be appreciated that any other shape may be used instead, and that the wrapping 20 may or may not substantially conform in respect of its shape to the shape of the cell it is intended to house.

For the purposes of illustration only, the openable portions 24 of the example wrappings 20a to 20f have been shown as a perforation for tearing open. However, it will be appreciated that one or more of the openable portions 24 may instead be configured to open upon application of a chemical process, or be otherwise configured to open to thereby permit the removal of a cell (not shown).

Figure 4A shows an example wrapping 20a, and figure 4B shows a similar example wrapping 20d, wherein the wrappings 20a, 20d may comprise a first portion 22 at a lower section (as defined relative to an orientation of a battery assembly), a removeable portion 26 at an upper section, and an openable portion 24 defining the boundary therebetween. The openable portion 24 may be arranged further towards the upper section such that a surface area of the first portion 22 may be increased for improved bonding with a potting compound.

During a disassembly process, the removeable portion 26 may be torn off in a controlled and guided manner, the tearing being assisted and localized to the structural weaking comprised in the openable portion 24. An opening aid in the form of a pull tab or flap may be further provided, in some examples, to assist in tearing or pulling the openable portion 24 open.

Figure 4A further shows an example wrapping 20b, and figure 4B shows a similar example wrapping 20e, wherein the openable portion 24 extends across a length of the upper surface of the wrapping 20. As illustrated in respect of wrappings 20c and 20f in figures 4A and 4B respectively, the openable portion 24 may instead extend across a width or depth/thickness of the wrapping 20 in some examples.

During a disassembly process, the openable portion 24 may be tom open and the resulting sections of the wrapping 20 may be pulled apart to thereby expose and permit removal of a cell housed therein. An example disassembly process is schematically shown in figures 5A and 5B, and illustrated in figure 8.

A method 800 for disassembling a potted battery assembly 500 may comprise opening 810 the openable portion 24 of a wrapped cell 21 , as indicated by the arrow in figure 5A. The opening 810 may comprise a tearing or pulling, an application of a chemical agent or solvent, and/or a heating or other process, depending on the implementation.

The method 800 may further comprise removing 820 the cell 14 from the wrapping 20, as indicated by the arrow in figure 5B. The cell 14 may be removed by manual or automatic means, under the action of gravity, or in any other suitable way, depending on the implementation.

Although all of the illustrated wrappings 20a to 20f show the openable portion 24 as a dotted line, it will be appreciated that this may be purely illustrative for the purpose of showing the possible location of the openable portion 24. In some examples, the location of the openable portion 24 may not be (clearly) visible. In other examples, the location of the openable portion 24 may be marked as an opening aid such that opening the openable portion 24 of the wrapping 20 may be made easier.

In some examples, the openable portions 24 of multiple wrappings 20 may be opened simultaneously, for example as part of a single mechanical or chemical action. Thus, the disassembly of a potted battery assembly may advantageously be made more fast and efficient.

Figures 6A and 6B show an example disassembly process for a potted battery assembly 600 having potting compound 15 arranged in sections 15a to 15c.

In the illustrated example, the potted battery assembly 600 may comprise a plurality of wrapped cells 21 , wherein the wrappings 20 may comprise a first portion 22a bonded to a first section 15a of the potting compound 15, and a second portion 22b of the wrapping bonded to a second section 15c of the potting compound 15. The first section 15a and the second section 15c of the potting compound 15 may be made of a same or a different material, having relatively higher adhesive properties. The openable portion 24 in the wrappings 20 of the wrapped cells 21 may be arranged between the first section 15a and the second section 15b of the potting compound 15 such that a moving apart of the first section 15a and the second section 15c may cause the openable portion 24 to open (e.g., by tearing or ripping, as a result of a structural or chemically-induced weakening).

The potting compound 15 may further comprise a third section 15b configured to occupy a space between the first section 15a and the second section 15c. The third section 15b may also be configured for a weaker bonding between the third section 15b and the openable portion 24 than the bonding between the first section 15a and the first portion 22a, and the second section 15c and the second portion 22b.

Thus, when the first section 15a and the second section 15c of the potting compound 15 are separated, as indicated by the arrows, the third section 15b may readily split, crumble, or otherwise break apart to thereby allow the openable portions 24 to open. That is, the third section 15b may preferably be not so adhesive as to seal the openable portions 24 shut.

According to such an illustrated approach, the openable portions 24 may advantageously be opened in a single step, requiring only a grip or mechanical connection to at least one of the first section 15a and the second section 15c. Thus, an automation or simplification of a disassembly process for the potted battery assembly 600 may be provided.

It will be appreciated that the implementations described above in relation to figures 2 through 8 are but examples of many which may fall within the scope of the present disclosure, and these illustrated examples have been provided merely to assist in understanding particular aspects of the present disclosure.

Any reference to prior art documents or comparative examples in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Furthermore, whilst the present disclosure is susceptible to various modifications and alternative forms, specific embodiments are shown and described by way of example in relation to the drawings, with a view to clearly explaining the various advantageous aspects of the present disclosure. It should be understood, however, that the detailed description herein and the drawings attached hereto are not intended to limit the disclosure to the particular form disclosed. Rather, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the following claims.

Claims

1 . A potted battery assembly (200, 500, 600) comprising: a cell (14) housed in a wrapping (20) to thereby form a wrapped cell

(21 ); and a potting compound (15) arranged to bond the wrapped cell (21 ) into the battery assembly (200, 500, 600); wherein the wrapping (20) comprises: a first portion (22) bonded to the potting compound (15); an openable portion (24) configured to open to thereby permit removal of the cell (14) from the wrapping (20).

2. The potted battery assembly (200, 500, 600) according to claim 1 , wherein: the openable portion (24) comprises a structural weaking.

3. The potted battery assembly (200, 500, 600) according to claim 2, wherein: the structural weaking is arranged to accommodate structural stresses during normal operations of the cell (14).

4. The potted battery assembly (200, 500, 600) according to any preceding claim, wherein: the openable portion (24) is configured to open upon application of a chemical process.

5. The potted battery assembly (200, 500, 600) according to any preceding claim, wherein: the wrapping (20) further comprises a removable portion (26) removably attached to the first portion (22) via the openable portion (24).

6. The potted battery assembly (200, 500, 600) according to any preceding claim, wherein: an inner surface of the wrapping and/or an outer surface of the cell (14) is configured to permit removal of the cell (14) from the wrapping (20).

7. The potted battery assembly (200, 500, 600) according to any preceding claim, wherein: the wrapping (20) comprises one or more materials selected for compatibility with a recycling process for the potting compound (15).

8. The potted battery assembly according to any preceding claim, wherein: the wrapping further comprises an opening aid configured to facilitate opening of the openable portion (24).

9. The potted battery assembly (200, 500, 600) according to any preceding claim, wherein: the potting compound (15) is arranged as multiple sections (15a, 15c) respectively bonded to separate portions (22a, 22b) of the wrapping (20); the first portion (22a) is bonded to a first section (15a) of the potting compound; a second portion (22b) of the wrapping (20) is bonded to a second section (15c) of the potting compound (15); and the openable portion (24) is arranged between the first portion (22a) and the second portion (22b).

10. The potted battery assembly (200, 500, 600) according to claim 9, further comprising: a third section (15b) of the potting compound (15) configured to occupy a space between the first section (15a) and the second section (15c); wherein the third section (15b) is configured for a weaker bonding between the third section (15b) and the openable portion (24) than the bonding between: the first section (15a) and the first portion (22a), and the second section (15c) and the second portion (22b).

11. A method (700) for assembling the potted battery module (200, 500, 600) of any of claims 1 to 10, comprising: arranging (710) at least one wrapped cell in an intended position in the battery assembly; fixing (720) said at least one wrapped cell at the intended position at least by bonding the potting compound to the first portion of the wrapping.

12. A method (800) for disassembling the potted battery assembly (200, 500, 600) of any of claims 1 to 10, comprising: opening (810) the openable portion of a wrapped cell to thereby permit removal of the cell from the wrapping; and removing (820) the cell from the wrapping.

13. The method (800) according to claim 12, wherein the method is for disassembling the potted battery assembly claim 4, wherein: opening (810) the openable portion of the wrapped cell comprises applying a chemical compound configured to cause the openable portion to open.

14. The method according to claim 12, wherein the method is for disassembling the potted battery assembly claim 9 or 10, wherein: opening (810) the openable portion of the wrapped cell comprises separating the first section and the second section of the potting compound.

15. A wrapping (20) for housing a cell (14) being adapted for use in the potted battery assembly (200, 500, 600) according to any of claims 1 to 10.