A cylindrical battery cell

Abstract

A cylindrical battery cell comprising: a can, which provides a first battery terminal of the cell; an electrode assembly within the can; a battery terminal part, which provides a second battery terminal of the cell; a current collecting disc that is electrically connected to both the electrode assembly and the battery terminal part; an electrical insulation disc that sits between the can and the current collecting disc in order to galvanically isolate the can from the current collecting disc; and wherein the electrical insulation disc has one or more protrusions that extend axially towards the current collecting disc in order to define one or more cavities between the electrical insulation disc and the current collecting disc.

Description

[0001] A CYLINDRICAL BATTERY CELL

[0002] Field

[0003] The present disclosure relates to cylindrical battery cells.

[0004] Summary

[0005] According to the first aspect of the present disclosure there is provided a cylindrical battery cell comprising: a can, which provides a first battery terminal of the cell; an electrode assembly within the can; a battery terminal part, which provides a second battery terminal of the cell; a current collecting disc that is electrically connected to both the electrode assembly and the battery terminal part; and an electrical insulation disc that sits between the can and the current collecting disc in order to galvanically isolate the can from the current collecting disc; wherein the electrical insulation disc has one or more protrusions that extend axially towards the current collecting disc in order to define one or more cavities between the electrical insulation disc and the current collecting disc.

[0006] Advantageously, the cavities define a volume into which electrolyte can flow when it moves out of the electrode assembly without resulting in a significant increase in pressure within the can. Furthermore, the electrical insulation disc provides galvanic isolation between the current collecting disc and the can, and it also acts as a lightweight spacer between the can and the current collecting disc.

[0007] The electrical insulation disc may further comprise an axially extending lip at the periphery of the electrical insulation disc. The axially extending lip may extend towards the electrode assembly and alongside at least part of the current collecting disc.

[0008] The axially extending lip may extend alongside the entire current collecting disc.

[0009] The electrical insulation disc may have a hole through its thickness. The battery terminal part may pass through the hole in the electrical insulation disc in order to be electrically connected to the current collecting disc.

[0010] The one or more protrusions may comprise one or more circumferential ribs. A surface of the electrical insulation disc that faces away from the current collecting disc may have one or more recesses.

[0011] The electrical insulation disc may have a uniform thickness such that the surface of the electrical insulation disc that faces away from the current collecting disc has a recess that corresponds to the protrusion from the opposite surface of the electrical insulation disc.

[0012] The electrical insulation disc may have an outer surface that faces away from the current collecting disc. The outer surface of the electrical insulation disc may be substantially planar. The electrical insulation disc may have: relatively thick regions that correspond to the location of the one or more protrusions; and relatively thin regions that correspond to locations of the electrical insulation disc that do not include a protrusion.

[0013] The current collecting disc may have one or more holes through its thickness. The one or more protrusions of the electrical insulation disc may be aligned such that they do not overlap with the holes in the current collecting disc.

[0014] The electrode assembly may comprise a jelly-roll and a liquid electrolyte.

[0015] The battery terminal part may comprise a rivet.

[0016] There is also provided a cylindrical battery cell comprising : a can, which provides a first battery terminal of the cell; an electrode assembly within the can; a battery terminal part, which provides a second battery terminal of the cell; a current collecting disc that is electrically connected to both the electrode assembly and the battery terminal part; and an electrical insulation disc that sits between the can and the current collecting disc in order to galvanically isolate the can from the current collecting disc; wherein the electrical insulation disc further comprises an axially extending lip at the periphery of the electrical insulation disc, wherein the axially extending lip extends towards the electrode assembly and alongside at least part of the current collecting disc. The electrical insulation disc may have one or more protrusions that extend axially towards the current collecting disc in order to define one or more cavities between the electrical insulation disc and the current collecting disc.

[0017] The cylindrical battery may further comprise: an electrically insulating gasket, which is located between the battery terminal part and the can in order to galvanically isolate the battery terminal part from the can. The electrically insulating gasket may be a separate component to the electrical insulation disc.

[0018] Brief Description of Drawings

[0019] One or more embodiments will now be described by way of example only with reference to the accompanying drawings in which:

[0020] Figure 1 shows an exploded diagram of a cylindrical battery cell that illustrates its internal structure;

[0021] Figure 2 shows a partial cross-sectional view of an example embodiment of a cylindrical battery cell according to the present disclosure; and

[0022] Figure 3 shows a partial cross-sectional view of another example embodiment of a cylindrical battery cell according to the present disclosure.

[0023] Detailed Description

[0024] Figure 1 shows an exploded diagram of a cylindrical battery cell 100 that illustrates its internal structure. The battery cell 100 comprises a substantially cylindrical casing, known in the art as a can 101, and a cylinder-shaped electrode assembly, known in the art as a jelly-roll 102, which is received within the can 101. In some example embodiments, the can 101 is also filled with a liquid electrolyte (not shown).

[0025] The jelly-roll 102 comprises a layered assembly of an anode layer, a cathode layer and at least one separator layer between the anode and cathode layer, each comprising a long conductive sheet or foil coated with an active material, as well as the aforementioned active materials. Once the layers are wound together, the jelly-roll 102 comprises a substantially cylindrical body 103 having a first end 104 and a second end 105, which opposes the first end 104. In case of using a solid electrolyte, the separator layers may be replaced by a sheet of solid electrolyte. Alternatively, solid electrolyte may be applied as a coating to either, or all, active material coatings.

[0026] The anode layer and the cathode layer comprise exposed parts, free from electrode coating. In this example, the exposed part of the cathode layer, which will be referred to as the cathode foil, extends from the longitudinal edge of the cathode layer that is uppermost in Figure 1 such that it can be electrically connected to an electrically conductive current collecting disc 108. The exposed part of the anode layer, which will be referred to as the anode foil, extends from the longitudinal edge of the anode layer that is lowermost in Figure 1 such that it can be electrically connected to an electrically conductive anode disc 113, or alternatively, directly to a lid 115, if the anode disc and the lid is one part.

[0027] Figure 1 also shows a plurality of first end components 106. The first end components

[0028] 106 comprise a battery terminal part, which in this example is a rivet 107. The rivet

[0029] 107 closes the can 101 at the first end. The rivet 107 also acts as a positive battery terminal for the cell. It should be noted that the polarity may be changed by inserting the jelly roll in the opposite direction. Such a change would require some material adjustments that would be apparent to the skilled person. The rivet 107 is configured to be electrically coupled, such as by welding, to the electrically conductive current collecting disc 108 that electrically connects to the cathode foil of the jelly-roll 102 and is received within the can 101. A gasket 110 is provided for sealing and electrical insulation between the rivet / battery terminal 107 and the can 101. It should be noted that the rivet 107 can be realised in different ways and may not be a rivet as such.

[0030] An electrical insulation disc 109 provides for electrical insulation between the current collecting disc 108 and the inside surface of the can 101. The electrical insulation disc 109 can comprise, or be made of, polypropylene, although it will be appreciated that any other suitable material, which is an electrically insulator, can be used. For instance, the electrical insulation disc 109 may be formed of a polymer having elastic, resilient, and electrically insulating properties, such as polyphenylene sulfide (PPS), ethylene propylene diene monomer (EPDM) rubber, polyethersulphone, (PES), or polyketone (PK). It will be appreciated that more than two materials may be used in other examples, depending on the implementation, in other arrangements. The electrical insulation disc 109 may be formed of two or more materials by injection molding, overmolding, 3D printing, and / or other techniques known to those skilled in the art. The second end components 111 in this example comprise the anode disc 113, which is provided to connect to the anode foil of the jelly-roll and act as a current collector. In this example the anode disc 113 is electrically connected to the can 101 such that the can 101 provides the anode terminal of the cylindrical battery cell 100. A lid gasket 114 is provided over the anode disc to provide for sealing of a lid 115 which closes the second end of the can 101. A seal plug 116 is provided to seal the can 101 by slotting into an aperture in the lid 115. A seal cap 117 finally closes the cell.

[0031] It will be appreciated, however, that the second end of the can 101 can be closed in any of a number of suitable ways. This may, or may not, include welding. Additionally, the second end of the 101 can be closed with or without the anode disc 113 in the bottom. If the anode disc 113 is not used, then the lid 115 can provide the functionality of the current collecting disc.

[0032] Figure 2 shows a partial cross-sectional view of an example embodiment of a cylindrical battery cell according to the present disclosure. As will be described below, advantageously the cell includes an electrical insulation disc 209 that is shaped such that it defines one or more cavities 222a, 222b between the electrical insulation disc 209 and a current collecting disc 208.

[0033] The cylindrical battery cell includes a can 201, a first end of which is shown in Figure 2. Figure 2 also shows a first end of an electrode assembly 203 within the can 201. In this example, the can 201 is electrically connected to the second end of the electrode assembly 203 (not shown in Figure 2), such that it provides a first battery terminal of the cell. The can 201 provides the negative battery terminal of the cell in the example of Figure 2.

[0034] Figure 2 also shows a battery terminal part 207, which in the implementation of Figure 2 is a rivet. The battery terminal part 207 provides a second battery terminal of the cell, which in this example is the positive battery terminal of the cell. The battery terminal part 207 is mechanically connected to, and electrically insulated from, the can 201. As shown in Figure 2, an electrically insulating gasket 210 can be located between the battery terminal part 207 and the can 201 in order to galvanically isolate the two components and thereby prevent a short circuit.

[0035] The cylindrical cell of Figure 2 also includes a current collecting disc 208. The current collecting disc 208 is electrically, galvanically, connected to the cathode foil 218 of the electrode assembly 203. Such an electrical connection can be made by notching the and then folding the cathode foil 218, and then welding the current collecting disc 208 to the cathode foil 218; or by pressing the cathode foil 218 to make it flat, which is known in the art as kneading, and then arranging the current collecting disc 208 directly onto the kneaded cathode foil 218. There are several ways to flatten the cathode foil before arranging the current collecting disc 208 on it; for example, partly kneading the cathode foil or cutting different shapes of the foil before bending it.

[0036] The current collecting disc 208 is also electrically, galvanically, connected to the battery terminal part 207. In this way, the current collecting disc 208 provides an electrical connection between the electrode assembly 203 and the battery terminal part 207.

[0037] In this example, the electrically insulating gasket 210 is a separate component to the electrical insulation disc 209. This can represent an efficient way of providing the cylindrical cell in terms of manufacturing processes, when compared with an alternative design in which the electrically insulating gasket and the electrical insulation disc are provided as a single component. Also, providing the electrically insulating gasket 210 and the electrical insulation disc 209 as separate components enables them each to comprise different materials, that are best suited to the needs of the respective components. For instance, it can be beneficial for the electrically insulating gasket 210 to have sealant properties, that are not as relevant for the electrical insulation disc 209.

[0038] The electrical insulation disc 209 that is shown in Figure 2 sits between the can 201 and the current collecting disc 208. The electrical insulation disc 209 galvanically isolates the can 201 from the current collecting disc 208 in order to avoid a potential short circuit if the components were to come into contact with each other.

[0039] It will be appreciated that any of the discs described herein may, or may not, have a circular shape when viewed from above. For example, a disc may be star shaped, square, oval or any other suitable shape.

[0040] The electrical insulation disc 209 includes one or more protrusions 220a, 220b that extend axially towards the current collecting disc 208. In this example, the protrusions are provided as two circumferential ribs 220a, 220b. The circumferential ribs 220a, 220b are concentric in Figure 2. One or both of the circumferential ribs 220a, 220b can be continuous such that they extend circumferentially around the electrical insulation disc 209 without any significant interruptions. In other examples, one or both of the circumferential ribs 220a, 220b can be discontinuous such that there are one or more gaps in a circumferential rib. Furthermore, it will be appreciated that a circumferential may have a circular profile when viewed along the axis of the cylindrical cell, but it could have a non-circular profile. In a yet further example, the electrical insulation disc 209 may include one or more protrusions that are implemented as radially extending ribs.

[0041] Irrespective of how the protrusions 220a, 220b on the electrical insulation disc 209 are implemented, the electrical insulation disc 209 includes indented regions between the protrusions. Such an indentation is considered with reference to a plane that includes the outermost surface of the protrusions 220a, 220b. The indented regions include a surface that is spaced apart from the current collecting disc 208. In this way, the one or more cavities 222a, 222b are defined between the electrical insulation disc 209 and the current collecting disc 208.

[0042] The electrical insulation disc 209 has a surface 225 that faces away from the current collecting disc 208. This surface 225 can be considered as an outer surface of the electrical insulation disc 209. In the example of Figure 2, the outer surface 205 of the electrical insulation disc 209 is substantially planar. In this way, the electrical insulation disc 209 has: relatively thick regions that correspond to the location of a protrusion 220a, 220b; and relatively thin regions that correspond to locations of the electrical insulation disc 209 that do not include a protrusion 220a, 220b. In other words, the regions of the electrical insulation disc 209 that correspond to the location of a protrusion 220a, 220b are thicker than the regions of the electrical insulation disc 209 that do not include a protrusion 220a, 220b. The cavities 222a, 222b are provided adjacent to the relatively thin regions of the electrical insulation disc 209. Such an electrical insulation disc 209 can provide good stability to the first end of the cell such that the components in this part of the cell are reliably held in the correct positions.

[0043] Advantageously, the electrical insulation disc 209 with one or more protrusions 220a, 220b provides the following functionality: i) it provides galvanic isolation between the current collecting disc 208 and the can 201; ii) it acts as a spacer between the can 201 and the current collecting disc 208, such that the protrusions can contact the current collecting disc 208 and therefore can help keep the current collecting disc 208 and the electrode assembly 203 in the correct position; and iii) it provides cavities 222a, 222b that are available for receiving liquid electrolyte. In relation to item ii), it can be important that the cell is able to withstand vibrations without components being displaced, which would degrade the performance of the cell. Therefore, the presence of the one or more protrusions 220a, 220b can assist with making the cell resilient to vibrations. In relation to item iii), it is known that electrolyte can move in and out of the electrode assembly 203 while the cell is being charged or discharged. Therefore, the cavities 222a, 222b between the protrusions 220a, 220b provide a volume into which the electrolyte can flow when it moves out of the electrode assembly 203 without resulting in a significant increase in pressure within the can 201.

[0044] Furthermore, the use of an electrical insulation disc 209 with protrusions 220a, 220b and cavities 222a, 222b results in an electrical insulation disc 209 that is lighter weight than a solid electrical insulation disc that has the same thickness as that of the regions of the electrical insulation disc 209 in Figure 2 that have the protrusions 2220a, 220b. This represents a very significant advantage because it enables a cell with a relatively high energy density to be achieved.

[0045] It will be appreciated that the electrical insulation disc 209 can be provided with any number of protrusions, of any shape, and in any arrangement in order to provide the functionality that is described above. For instance, the protrusions can include regularly or irregularly spaced, they can include continuous or discontinuous ribs, and I or they can include any pattern of dots.

[0046] As shown in the figures, the electrical insulation disc 209 has a hole through its thickness at its centre. The battery terminal part 207 passes through the hole in the electrical insulation disc 209 (and also through a hole in the can 201) such that it can be electrically connected to the current collecting disc 208.

[0047] Figure 3 shows a partial cross-sectional view of another example embodiment of a cylindrical battery cell according to the present disclosure. Features of Figure 3 that have corresponding features in Figure 2 are given corresponding reference numbers in the 300 series, and will not necessarily be described again here.

[0048] As shown in Figure 3, in this example an outer surface of the electrical insulation disc 309 (i.e., the one that faces away from the current collecting disc 308) includes one or more recesses 323. A benefit of including such recesses 323 is that they can further improve electrolyte flow within the battery cell. Another benefit of including the recesses 323 is that the electrical insulation disc 309 requires less material than would be the case if the outer surface of the electrical insulation disc 309 were planar.

[0049] In the particular implementation of Figure 3, the electrical insulation disc 309 has a single circumferential protrusion 320, which defines a first cavity 322a that is radially outwards from the protrusion 320 and a second cavity 322b that is radially inwards from the protrusion 320. The circumferential protrusion 320 has an outer surface, which faces towards the current collecting disc 308, that is closer to the current collecting disc 308 than the surface of the electrical insulation disc 309 between the protrusions 320. In this example, the electrical insulation disc 309 has a uniform thickness such that an outer surface of the electrical insulation disc 309 (i.e., a surface that faces away from the current collecting disc 308) has a recess 323 that corresponds to the protrusion 320 from the opposite surface of the electrical insulation disc 309. In some applications, it can be easier to manufacture an electrical insulation disc 309 that has a uniform thickness. This can especially be the case when injection moulding the electrical insulation disc 309.

[0050] Although Figure 3 shows the electrically insulating gasket 310 and the electrical insulation disc 309 as separate components, for any of the examples described herein the functionality of both components can be provided as a single, unitary, component.

[0051] Optionally, the current collecting disc 308 can have one or more holes through its thickness. (Examples of such holes can be seen in Figure 1.) This can be to allow electrolyte to flow through the current collecting disc 308. If such holes are present, then the protrusion (or protrusions) 320 of the electrical insulation disc 309 can be aligned such that they do not overlap with the holes in the current collecting disc 308. This ensures that the protrusion (or protrusions) 320 do not obstruct the flow of electrolyte through the current collecting disc 308.

[0052] The electrical insulation disc 309 of Figure 3 (and also the electrical insulation disc 209 of Figure 2) includes an axially extending lip 324 at the periphery of the electrical insulation disc 309. The axially extending lip 324 extends towards the electrode assembly 303, and alongside at least part of the current collecting disc 308. In some examples, the axially extending lip 324 extends alongside the entire current collecting disc 308. In some implementations, the electrical insulation disc 309 can include one or both of: i) one or more protrusions 320; and ii) the axially extending lip 324. That is, an electrical insulation disc can be provided that includes one or more protrusions but not necessarily an axially extending lip, and vice versa.

[0053] The axially extending lip 324 provides additional galvanic isolation between the current collecting disc 308 and the can 301. In particular, it provides an electrically insulating barrier between the peripheral edges of the current collecting disc 308 and the can 301. This can be especially beneficial if the current collecting disc has a diameter to cover most of the end surface of the electrode assembly such that its edge is arranged close to the can. The axially extending lip 324 is then making sure that there will be no contact between the current collecting disc and the can, even in a case where the battery cell is subjected to external force so that the electrode assembly and the current collecting disc moves in relation to the can. In this way, the axially extending lip 324 can provide side protection against a short circuit.

[0054] Advantages of the protrusions described herein include: providing the functionality of a structure support for the jelly-roll in order to prevent excessive movement of the jelly-roll due to vibration and shock during use in the application; keeping the current collecting disc flat; and maintaining the integrity of welds between the current collecting disc and the jelly-roll (i.e., there is no or only limited localized deformation).

Claims

Claims1. A cylindrical battery cell comprising: a can, which provides a first battery terminal of the cell; an electrode assembly within the can; a battery terminal part, which provides a second battery terminal of the cell; a current collecting disc that is electrically connected to both the electrode assembly and the battery terminal part; and an electrical insulation disc that sits between the can and the current collecting disc in order to galvanically isolate the can from the current collecting disc; wherein the electrical insulation disc has one or more protrusions that extend axially towards the current collecting disc in order to define one or more cavities between the electrical insulation disc and the current collecting disc.

2. The cylindrical battery cell of claim 1, wherein the electrical insulation disc further comprises an axially extending lip at the periphery of the electrical insulation disc, wherein the axially extending lip extends towards the electrode assembly and alongside at least part of the current collecting disc.

3. The cylindrical battery cell of claim 2, wherein the axially extending lip extends alongside the entire current collecting disc.

4. The cylindrical battery cell of any preceding claim, wherein: the electrical insulation disc has a hole through its thickness; and the battery terminal part passes through the hole in the electrical insulation disc in order to be electrically connected to the current collecting disc.

5. The cylindrical battery cell of any preceding claim, wherein the one or more protrusions comprise one or more circumferential ribs.

6. The cylindrical battery cell of any preceding claim, wherein a surface of the electrical insulation disc that faces away from the current collecting disc has one or more recesses.

7. The cylindrical battery cell of claim 6, wherein the electrical insulation disc has a uniform thickness such that the surface of the electrical insulation disc that faces away from the current collecting disc has a recess that corresponds to the protrusion from the opposite surface of the electrical insulation disc.

8. The cylindrical battery cell of any one of claims 1 to 5, wherein : the electrical insulation disc has an outer surface that faces away from the current collecting disc; and the outer surface of the electrical insulation disc is substantially planar.

9. The cylindrical battery cell of claim 8, wherein the electrical insulation disc has: relatively thick regions that correspond to the location of the one or more protrusions; and relatively thin regions that correspond to locations of the electrical insulation disc that do not include a protrusion.

10. The cylindrical battery cell of any preceding claim, wherein: the current collecting disc has one or more holes through its thickness; and the one or more protrusions of the electrical insulation disc are aligned such that they do not overlap with the holes in the current collecting disc.

11. The cylindrical battery cell of any preceding claim, wherein the electrode assembly comprises a jelly-roll and a liquid electrolyte.

12. The cylindrical battery cell of any preceding claim, wherein the battery terminal part comprises a rivet.

13. The cylindrical battery cell of any preceding claim, further comprising: an electrically insulating gasket, which is located between the battery terminal part and the can in order to galvanically isolate the battery terminal part from the can, wherein the electrically insulating gasket is a separate component to the electrical insulation disc.

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