GB2579035A

GB2579035A - Battery

Info

Publication number: GB2579035A
Application number: GB1818625.4A
Authority: GB
Inventors: Malone Adam; Kerby Paul
Original assignee: Pab Coventry Ltd; Pak Eng
Current assignee: Pab Coventry Ltd; Pak Eng
Priority date: 2018-11-15
Filing date: 2018-11-15
Publication date: 2020-06-10
Also published as: GB201818625D0

Abstract

A battery comprises a plurality of cells 1 and a conditioning system, which comprises a manifold 2 and a plurality of hollow polymer fibres 3 in fluid communication with the manifold and through which a cooling and/or heating fluid (liquid or gas) can flow, wherein the hollowpolymer fibres contact the cells. The hollow fibres 3 may be wrapped around the cells 1 in a number of different ways, e.g. so that they are wrapped around one row of cells and in contact with a second row of cells (as shown), or coiled around single cells. The hollow fibres may be made from a thermoplastic polymer such as PEEK or PTFE, and may have an outer diameter less than 3.5 mm, e.g. less than 1 mm.

Description

Battery The present invention relates to a battery, in particular to a battery comprising a conditioning system, which may be used for cooling and/or heating cells of the battery.

Electric vehicles use large batteries to store energy. These typically comprise, though are not limited to, a large number of Lithium-Ion cells. The performance of Lithium-Ion cells is greatly impacted by their temperature. They do not perform well when too hot. Heat can lead to permanent damage of the cells and/or accelerated degradation. They also do not perform well when too cold.

One known means of cooling the cells is by circulating water based coolant through cooling passages within a battery structure. The present inventors have noted various shortcomings with the prior art cooling arrangements. The present invention arose in a bid to provide an improved battery conditioning structure.

According to the present invention, in a first aspect, there is provided a battery comprising a plurality of cells and a conditioning system, which comprises a manifold and a plurality of hollow polymer fibres in fluid communication with the manifold and through which a cooling and/or heating fluid, or gas, can flow, wherein the hollow polymer fibres contact the cells.

The use of hollow polymer fibres offers a number of advantages over prior art arrangements, including weight savings, due to the comparatively low weight of the polymer fibres versus prior art metallic arrangements, and improved cooling performance

over those prior art arrangements.

The hollow polymer fibres are readily manipulated and may be wrapped around the cells, so as to conform, at least in part, to the outer profiles of the cells.

A greater surface contact with the cells can be achieved than with prior art arrangements, which increases the heat transfer coefficient and improves performance.

The ease of manipulation of the hollow polymer fibres and their small size (they may have an external diameter of 3.5mm or less, and more preferably 1mm or less) allows for the production of high density/compact cell banks within a battery, whilst achieving a significant contact area between the hollow polymer fibres and the cells. A number of configurations are possible in which the hollow polymer fibres are wrapped around the cells. The fibres may contact anywhere between 30 and 100% of the outer profile of each of the cells they are wrapped around, in dependence on the configuration adopted.

The cells may be arranged in at least a first row of cells and a second row of cells, with the first row of cells adjacent to the second row of cells, wherein the cells of the first and second rows are offset from one another and portions of the hollow polymer fibres that wrap around the cells of the first row contact the cells of the second row and/or contact portions of the hollow polymer fibres that wrap around the cells of the second row and portions of the hollow polymer fibres that wrap around the cells of the second row contact the cells of the first row and/or contact portions of the hollow polymer fibres that wrap around the cells of the first row.

Further, preferable, features are presented in the dependent claims.

Non-limiting embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawing, in which: Figure 1 is a partial perspective view of a battery according to one embodiment of the present invention.

With reference to Figure 1, there is shown a partial view of a battery, which comprises a plurality of cells 1 and a conditioning system, which comprises a manifold 2 and a plurality of hollow polymer fibres 3 in fluid communication with the manifold and through which a cooling and/or heating fluid, or gas, can flow. As can be seen, the hollow polymer fibres contact the cells.

The partial view of Figure 1 shows a cell bank of the battery. The casing of the battery is omitted for clarity. Whilst the cell bank is shown to contain 19 cells it should be appreciated that there will typically be a much larger number of cells contained in any cell bank. The number of cells in any cell bank is not particularly limited. The battery may comprise a single cell bank, or, as is preferred, will contain a plurality of cell banks grouped together to form the battery. Numerous configurations in this regard will be possible.

In the arrangement of Figure 1, the cooling or heating fluid, or gas, is introduced into a first end of each of the hollow polymer fibres by an intake manifold. The fluid/gas will flow through the hollow polymer fibres (which are polymer tubes) to a second end of the hollow polymer fibres to an exit manifold. The intake and exit manifolds are connected to a conventional pump and heat exchange arrangement. These are not discussed in detail here and may take any suitable known form.

As is clear from Figure 1, the hollow polymer fibres are wrapped around the cells, so as to conform, at least in part, to the outer profiles of the cells. It is to be noted that Figure 1 shows a preferred wrapping configuration but that alternative wrapping configurations will be possible within the scope of the claims. One notable alternative, which is not shown, but is discussed further below, is the provision of coiled hollow polymer fibres. It is further to be noted that whilst the depicted cells are cylindrical in form they need not be, they could for example be parallelepiped in form, or could be in a pouch or prism form or otherwise.

The wrapping of the fibres around the cells provides for a large contact area with the cells. Each of the cells may have at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or 100% of its outer profile contacted by one or more of the hollow polymer fibres. In the arrangement of Figure 1, each of the cells has substantially 50% of its outer profile, i.e. circumference, contacted by the hollow polymer fibres that contact it. In a coiled arrangement, for example, 100% of the outer profiles of the cells will be contacted by the hollow polymer fibres.

As shown, the cells are arranged in at least a first row of cells and a second row of cells. The first row of cells is adjacent to the second row of cells. As will be appreciated by those skilled in the art, there will typically be a number of further rows of cells. The number of rows of cells is not to be limited. The cells of the first and second rows (i.e. the cells of adjacent rows when there are more than two rows of cells) are preferably offset.

This provides for the most efficient packing of the cylindrical cells. In dependence on the specific form/shape of the cells or any other design/packaging considerations, the rows may be otherwise arranged. Where the cells are cylindrical, adjacent rows need not be offset from one another, even though this is preferred. The aim will typically be to maximise the density of the cells, without detriment to the contact of the hollow polymer fibres with the cells (and the resultant heating/cooling efficiency), whilst working within any external constraints. Notably, cell density in some applications may not be critical, wherein this may also factor into the specific arrangement adopted. In the present arrangement with offset rows, there is the advantage (additional to the high density packing of the cells) that the portions of the hollow polymer fibres that wrap around the cells of the first row contact the cells of the second row and the portions of the hollow polymer fibres that wrap around the cells of the second row contact the cells of the first row. The same principal will apply to various alternative wrapping arrangements, as will be appreciated by those skilled in the art. In yet further alternatives, for example, where the hollow polymer fibres are coiled around the cells or are otherwise wrapped around the cells, it may be that portions of the hollow polymer fibres that wrap around the cells of the first row contact portions of the hollow polymer fibres that wrap around the cells of the second row and vice versa.

In the depicted arrangement, the hollow polymer fibres are arranged in parallel to one another. This may not be the case. In alternative arrangements, in particular in a spiral arrangement, they may be otherwise arranged. The fibres may also be interwoven with one another/woven in an inter-locking arrangement. In an interwoven configuration, the fibres may together form a sheet or mat of fibres, which may be brought into contact with the cells. The sheet or mat may be wrapped around the cells or fed through and in between the cells, or otherwise, as will be readily appreciated by those skilled in the art.

When the hollow polymer fibres are provided in parallel to one another, adjacent fibres may be spaced from one another, as shown, but it is preferred that they contact one another so that the contact area with the cells is increased. The density of the parallel fibres may be dependent on specific cooling requirements. With the hollow polymer fibres extending parallel to one another as shown, each of the hollow polymer fibres may be considered to define one or more waveforms. In the present arrangement with two rows of cells, the hollow polymer fibres extending along the first row, weaving in and out of the cells of the first row, may be considered to define a waveform that is close to a sine wave in form. A second waveform is provided as the hollow polymer fibres extend back along the second row. Clearly with changes to the form of the cells that the hollow polymer fibres wrap around, the form of the waveform will change. With parallelepiped cells the waveform may be a square waveform for example.

The hollow polymer fibres may alternatively/further be considered to define a plurality of peaks and troughs, wherein adjacent cells are alternately received within the peaks and troughs. In the present arrangement, as shown, a single cell is received by each peak and a single cell is received by each trough. This arrangement is preferred to maximise contact between the hollow polymer fibres and cells. The adjacent cells of the first row of cells are alternately received within a first set of peaks and troughs, and adjacent cells of the second row of cells are alternately received within a second set of peaks and troughs. This is made possible by the size and ease of manipulation of the hollow polymer fibres. It may be contrasted with an arrangement where a cooling member passes between adjacent rows to separate those rows from one another with one row on a first side of the cooling member and an adjacent row of cells on the other side of the cooling member.

In the depicted arrangement, the manifolds are provided in parallel to the axes of the cells. This need not be the case, the manifolds may be otherwise oriented. For example, the manifolds could run perpendicular to the axes of the cells, or otherwise. The form of the manifolds is not particularly limited as long as they are in fluid communication with the hollow polymer fibres to provide for suitable fluid, or gas, flow therethrough.

In an alternative arrangement to the depicted arrangement, rather than the hollow polymer fibres running parallel to one another, the hollow polymer fibres may be coiled around the cells. In such an arrangement each of the cells may have a different one of the hollow polymer fibres coiled around it, i.e. every one of the cells may have a single unique hollow polymer fibre wrapped around it. This contrasts with the depicted arrangement in which each of the fibres contacts a number of the cells and each of the cells is contacted by a number of the hollow polymer fibres. However, alternative coiled arrangements are possible where a single hollow polymer fibre coils around a plurality of the cells or a number of fibres coil around each of the cells. Moreover, as defined above, the fibres may be woven into a mat or sheet, in such case, most preferably, a plurality of the fibres forming the mat will contact a number of the cells.

Where each of the cells has an individual, or pluraltity of, hollow polymer fibre(s) coiled around it, the hollow polymer fibres may have their outflow and inflow ends at the same end of the cells or at opposed ends of the cells. It is preferred that they are at opposed ends of the cells. In either case, it is preferable that the inflow and outflow manifolds extend perpendicular to the axes of the cells along the cell rows, wherein each of the hollow polymer fibres may be connected to the manifolds adjacent the respective cell it coils around, however this need not be the case, the manifolds may be otherwise oriented/located with the hollow polymer fibres suitably trailed to the manifolds. In the arrangement where the inflow and outflow ends of the coil are both at the same end of each of the cells, inflow and outflow portions of the hollow polymer fibre may be adjacent one another in each turn of the coil. Whether the manifolds are at the same end or at opposite ends of the cell or are otherwise oriented/located, the adjacent turns of the coils on each cell may be spaced from one another or abut one another.

The hollow polymer fibres are preferably formed from a thermoplastic polymer. They may be formed from polyether ether ketone (PEEK) or from polytetrafluoroethylene (PTFE), or any other suitable thermoplastic polymer. Suitable polymers may be selected on the basis of required operating conditions, as will be readily appreciated by those skilled in the art. The hollow polymer fibres preferably have an outer diameter of less than 3.5 millimetres. The hollow polymer fibres most preferably have an outer diameter of less than 1 millimetre and may have an outer diameter of 0.85mm or less. In a preferred arrangement, they have an outer diameter of 0.80mm±0.05mm. The wall thickness of the hollow polymer fibres may be less than 0.5mm, more preferably less than 0.3mm, 0.2mm, or 0.1mm. The wall thickness may depend on the outer diameter of the hollow polymer fibres.

The hollow polymer fibres may be potted in the manifolds, however they may also be welded. Alternative suitable attachment means will be appreciated by those skilled in the art.

To construct the battery, irrespective of the specific arrangement of hollow polymer fibres that is adopted, the hollow polymer fibres will be heated to above their glass transition temperature before being suitably wrapped around the cells of the battery and subsequently cooled.

The invention has been described above with reference to specific embodiments, given by way of example only. It will be appreciated by those skilled in the art that many different arrangements of the battery are possible, which fall within the scope of the appended claims.

Claims

Claims 1. A battery comprising a plurality of cells and a conditioning system, which comprises a manifold and a plurality of hollow polymer fibres in fluid communication with the manifold and through which a cooling and/or heating fluid or gas can flow, wherein the hollow polymer fibres contact the cells.
2. A battery as claimed in Claim 1, wherein the hollow polymer fibres are wrapped around the cells, so as to conform, at least in part, to the outer profiles of the cells.
3. A battery as claimed in Claim 2, wherein each of the cells has between 30% and 100% of its outer profile contacted by one or more of the hollow polymer fibres.
4. A battery as claimed in Claim 3, wherein the cells are substantially cylindrical and each of the cells has between 30% and 100% of its circumference contacted by one or more of the hollow polymer fibres.
5. A battery as claimed in any of Claims 2 to 4, wherein the cells are arranged in at least a first row of cells and a second row of cells, and the first row of cells is adjacent to the second row of cells, wherein the cells of the first and second rows are offset from one another and portions of the hollow polymer fibres that wrap around the cells of the first row contact the cells of the second row and/or portions of the hollow polymer fibres that wrap around the cells of the second row and portions of the hollow polymer fibres that wrap around the cells of the second row contact the cells of the first row and/or portions of the hollow polymer fibres that wrap around the cells of the first row.
6. A battery as claimed in any preceding claim, wherein each of the hollow polymer fibres defines a waveform.
7. A battery as claimed in any preceding claim, wherein the hollow polymer fibres are arranged in parallel to one another, or are interwoven with one another.
8. A battery as claimed in Claim 7, wherein adjacent hollow polymer fibres contact one another.
9. A battery as claimed in any preceding claim, wherein the hollow polymer fibres define a plurality of peaks and troughs, wherein adjacent cells are alternately received within the peaks and troughs.
10. A battery as claimed in any of Claims 2 to 9, wherein the cells are arranged in at least a first row of cells and a second row of cells, wherein the polymer fibres define a plurality of peaks and troughs, wherein adjacent cells of the first row of cells are alternately received within a first set of peaks and troughs, and adjacent cells of the second row of cells are alternately received within a second set of peaks and troughs.
11. A battery as claimed in Claim 9 or 10, wherein a single one of the cells is received by each of the peaks and troughs.
12. A battery as claimed in any of Claims 2 to 5, wherein the hollow polymer fibres are coiled around the cells.
13. A battery as claimed in Claim 12, wherein each of the cells has a different one of the hollow polymer fibres coiled around it.
14. A battery as claimed in Claim 12, wherein adjacent turns of each of the coils contact one another.
15. A battery as claimed in any preceding claim, wherein the hollow polymer fibres are formed from a thermoplastic polymer.
16. A battery as claimed in any preceding claim, wherein the hollow polymer fibres are formed from polyether ether ketone or polytetrafluoroethylener.
17. A battery as claimed in any preceding claim, wherein the hollow polymer fibres have an outer diameter of less than 3.5 millimetres.
18. A battery as claimed in any preceding claim, wherein the hollow polymer fibres have an outer diameter of less than 1 millimetre.