GB2551997A

GB2551997A - Battery cell arrangement

Info

Publication number: GB2551997A
Application number: GB1611727.7A
Authority: GB
Inventors: Algoo Robin
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2016-07-05
Filing date: 2016-07-05
Publication date: 2018-01-10
Anticipated expiration: 2036-07-05
Also published as: GB2551997B; GB201611727D0; WO2018007078A1

Abstract

An apparatus 101,101A, an electrical system for a vehicle, a vehicle, a method and a sheet are disclosed. The apparatus comprises a heat sink means 102 and a sheet 103 having at least a first portion 104, 104A positioned alongside the heat sink means 102. The sheet 103 comprises a layer of material 120 that is thermally conductive along the plane of the sheet 103. The apparatus also includes a plurality of battery cells 105, in which each battery cell 105 has an end wall 106 and a plurality of layers of electrode material 107 and each of the layers of electrode material 107 extend in a direction away from the end wall 106. The end walls 106 of the battery cells 105 are positioned alongside a different second portion 108 of the sheet 103.

Description

(71) Applicant(s):

Jaguar Land Rover Limited

Abbey Road, Whitley, Coventry, Warwickshire,

CV3 4LF, United Kingdom (72) Inventor(s):

Robin Algoo (51) INT CL:

H01M 6/50 (2006.01) H01M 10/655 (2014.01) (56) Documents Cited:

DE 102012219642 A1 US 20140295241 A1 US 20120251865 A1 (58) Field of Search:

INT CL H01M Other: EPODOC, WPI (74) Agent and/or Address for Service:

Jaguar Land Rover Limited

Abbey Road, Whitley, Coventry, Warwickshire,

CV3 4LF, United Kingdom (54) Title of the Invention: Battery cell arrangement

Abstract Title: Battery cell with a heat sink and conductive sheet arrangement (57) An apparatus 101,101 A, an electrical system for a vehicle, a vehicle, a method and a sheet are disclosed. The apparatus comprises a heat sink means 102 and a sheet 103 having at least a first portion 104, 104A positioned alongside the heat sink means 102. The sheet 103 comprises a layer of material 120 that is thermally conductive along the plane of the sheet 103. The apparatus also includes a plurality of battery cells 105, in which each battery cell 105 has an end wall 106 and a plurality of layers of electrode material 107 and each of the layers of electrode material 107 extend in a direction away from the end wall 106. The end walls 106 of the battery cells 105 are positioned alongside a different second portion 108 of the sheet 103.

Fig. 1

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Fig. 1

2/8

Fig. 2

3/8

Fig. 3

4/8

Fig. 4A

5/8

Fig. 5

6/8

101, 101A

	GENERATOR 604

	MOTOR 606
POWERTRAIN 605

ELECTRICAL

SYSTEM

602


	- .-...........! c...........! r...........!
		BATTERY 603

Fig. 6

VEHICLE

601

7/8

Fig. 7

700

8/8

Fig. 8

800

BATTERY CELL ARRANGEMENT

TECHNICAL FIELD

The present disclosure relates to a battery cell arrangement. In particular, but not exclusively it relates to a battery cell arrangement in a vehicle such as an electrically powered vehicle or a hybrid vehicle.

Aspects of the invention relate to an apparatus, an electrical system for a vehicle, a vehicle, a method and a sheet.

BACKGROUND

It has been proposed to provide thermal management of battery cells in a vehicle by locating each battery cell within a pouch, formed of a continuous carbon based film, which extends around the sides of the battery cell. The pouch has flaps designed to contact a cooling plate or heat sink. A problem with such an arrangement is that the outside surface of the battery cell is kept relatively cool but, due to relatively poor heat conduction through the layers of electrolyte in the battery cell, a temperature gradient can be created in which the middle of a battery cell is at a higher temperature than its outer surface. Such a temperature gradient can have a negative influence on the rate of ageing of the cell. That is, it can have a negative effect on the useful life of the battery cell.

It is an aim of the present invention to address the disadvantages of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide an apparatus, an electrical system, a vehicle, a method and a sheet as claimed in the appended claims.

According to an aspect of the invention there is provided an apparatus comprising: a heat sink means; a sheet having at least a first portion positioned alongside the heat sink means, the sheet comprising a layer of material that is thermally conductive along the plane of the sheet; a plurality of battery cells, each battery cell having an end wall and a plurality of layers of electrode material, each of the layers extending in a direction away from the end wall, wherein the end walls of the battery cells are positioned alongside a different second portion of the sheet.

This provides the advantage that heat may be transferred from the battery cells to the heat sink means without producing a radial temperature gradient within the battery cells. That is, large temperature gradients from the middle of the battery cell radially outwards are avoided. Consequently, cell ageing that would otherwise be caused by such a temperature gradient is avoided.

In some embodiments, the sheet comprises a layer of graphite material or a layer of metal. This provides that advantage that sufficient heat conductivity may be provided with relatively thin sheets of material.

The sheet may comprise a layer of highly oriented pyrolytic graphite. This provides that advantage that sufficient heat conductivity may be provided with a relatively thin and light sheet of material.

In a further embodiment, the sheet of thermally conductive material has a thickness of less than 8mm. Advantageously, the sheets of thermally conductive material having a thicker section which may form part of the rigid structure of the battery pack and so could perform a dual purpose of heat dissipation means and a mounting means.

In some embodiments, the sheet of thermally conductive material has a thickness in the range of less than 1 mm. Thinner sheets of material have the advantage of being able to conduct heat away from the end of the battery cells in package constrained locations, for example by having increased flexibility and reduced space requirements.

In another embodiment the sheet of thermally conductive material has a thickness between 0.01 and 0.1mm. The thinner the section of the sheet of thermally conductive material the higher is the in plane thermal conductivity and therefore the more efficient the thermally conductive material is at removing thermal energy from the battery cells.

In a further embodiment the sheet of thermally conductive material has a thickness of 0.1 mm.

In some embodiments, the sheet comprises a layer of electrically conductive material and the apparatus further comprises a layer of electrically insulating material disposed between the layer of electrically conductive material and the end walls of the battery cells. This provides the advantage that an electrically conductive material may be used to conduct heat away from the battery cells while the insulating material enables electrical leakage through the sheet to be avoided.

In some embodiments the layer of electrically insulating material provides a coating on the layer of electrically conductive material.

In some embodiments the sheet defines a plurality of first holes, each of the first holes corresponding to a respective one of the battery cells, and the apparatus further comprises a busbar and a plurality of electrical conductors, each electrical conductor being located through a respective one of the first holes and connecting the busbar to the respective battery cell. This provides the advantage that the sheet may be used to conduct heat from the end wall of a battery cells when the end wall provides one of the electrical terminals of the battery cells.

The sheet may be folded to extend from the battery cells around the busbar to the heat sink means. This provides the advantage that the heat sink means may be positioned further from the battery cells than the busbar is.

The sheet may folded to form a channel having a central second portion and two side portions extending from opposing sides of the central second portion, the battery cells are located alongside the central second portion, the heat sink means is located alongside the side portions and the busbar extends within the channel. This arrangement enables efficient extraction of heat from the base (or end wall) of the battery cells while enabling the nearby positioning of a busbar connected to the bases.

In some embodiments the battery cells located alongside the sheet form an array that is no more than two rows wide. Limiting the number of rows to no more than two, provides the advantage that heat may be efficiently extracted in a similar way from all of the battery cells.

In some embodiments, for each of the battery cells, a respective area of the sheet extending between the respective battery cell and the first portion of the sheet positioned alongside the heat sink means is free from other battery cells, and the respective battery cell is the nearest battery cell to all points within the area. This provides the advantage that all battery cells are provided with a clear conduction path to the heat sink means.

The heat sink means may comprise a heat sink defining channels for the passage of fluid to enable heat to be removed from the heat sink.

The battery cells are cylindrical battery cells having a central axis that extends away from the second portion of the sheet. This provides the advantage that temperature gradients across the battery cell (perpendicular to the axis) are kept to a minimum.

According to another aspect of the invention there is provided an electrical system of a vehicle in which the system comprises an apparatus as described above and comprising a motor configured to receive electrical energy from the battery cells of the apparatus.

The use of the thermally conductive sheet in the apparatus enables the battery cells to be efficiently cooled while taking up a relatively small volume in the vehicle and adding a relatively small mass to the vehicle.

According to another aspect of the invention there is provided a vehicle comprising an apparatus as described above or an electrical system as described above.

According to a further aspect of the invention there is provided a method of assembling a plurality of battery cells, the method comprising: positioning a plurality of battery cells, each battery cell having an end wall and a plurality of layers of electrode material that extend from the end wall, so that the end walls are positioned alongside a second portion of a sheet, the sheet comprising a layer of material that is thermally conductive along the plane of the sheet; and positioning at least a different first portion of the sheet alongside a heat sink means.

This provides the advantage that the battery cells may be simply assembled to form a battery, spaced separately from the heat sink means but in such a way that the battery cells may be efficiently cooled by the heat sink means.

In some embodiments, the sheet comprises a layer of electrically conductive material and a layer of electrically insulating material; and the positioning the plurality of battery cells comprises positioning the layer of electrically insulating material between the end walls of the plurality of battery cells and the layer of electrically conductive material.

In some embodiments, the sheet defines a plurality of first holes, and the method comprises positioning the end wall of each of the plurality of battery cells against a respective one of the first holes and connecting each of the end walls to a busbar by a respective electrical conductor located through the respective first hole.

In some embodiments, the method comprises folding the sheet so that the sheet extends from the battery cells around the busbar to the heat sink means.

In some embodiments, the method comprises folding the sheet around the support structure and supporting the support structure on the heat sink means with the at least first portion of the sheet located between the support structure and the heat sink means.

In some embodiments, the sheet is folded to form a channel having a central portion and two side portions extending from opposing sides of the central portion, and the method comprises positioning the battery cells to be in contact with the central portion, and bringing the heat sink means into contact with the side portions so that the busbar extends within the channel.

In some embodiments, the battery cells are positioned on the sheet to form an array that is no more than two rows wide.

In some embodiments, the battery cells each have one or more side walls extending from the end wall and the battery cells are positioned so that the sheet is not in contact with the one or more side walls.

According to a still further aspect of the invention there is provided a sheet comprising a layer of material that is thermally conductive along the plane of the sheet, wherein the sheet comprises: at least a first portion positioned alongside a heat sink; and a different second portion of the sheet positioned alongside an end wall of each one of a plurality battery cells, the end wall of each battery cell being positioned such that a plurality of layers of electrode material within the battery cell extend in a direction away from the end wall.

According to another further aspect of the invention there is provided an apparatus comprising: a heat sink defining passageways or channels for enabling the flow of a fluid; a sheet having at least a first portion positioned alongside the heat sink, the sheet comprising a layer of material that is thermally conductive along the plane of the sheet; a plurality of battery cells, each battery cell having an end wall and a plurality of layers of electrode material, each of the layers extending in a direction away from the end wall, wherein the end walls of the battery cells are positioned alongside a different second portion of the sheet.

The apparatus may be for providing electrical energy in a vehicle, such as an electric vehicle or a hybrid vehicle.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Fig. 1 shows an example apparatus 101 embodying the invention;

Fig. 2 shows an alternative example apparatus 101A embodying the invention;

Fig. 3 shows a more detailed cross-sectional view of the apparatus 101 A;

Fig. 4A shows a plan view of an example support structure 115A;

Fig. 4B shows an end view of the support structure 115A;

Fig. 5 shows a plan view of an example sheet 103 before folding and configured for assembly to the support structure 115A;

Fig. 6 shows schematically a vehicle 601;

Fig. 7 shows a flowchart of an example method 700 of assembling an apparatus; and Fig. 8 shows a flowchart of an example method 800 of assembling an apparatus.

DETAILED DESCRIPTION

The Figures illustrate an apparatus 101, 101A comprising: a heat sink means 102; a sheet 103 having at least a first portion 104, 104A positioned alongside the heat sink means 102, the sheet 103 comprising a layer 120 of material that is thermally conductive along the plane of the sheet 103; a plurality of battery cells 105, each battery cell 105 having an end wall 106 and a plurality of layers of electrode material 107, each of the layers 107 extending in a direction away from the end wall 106, wherein the end walls 106 of the battery cells 105 are positioned alongside a different second portion 108 of the sheet 103.

In the illustrated embodiments, the sheet 103 comprises a layer 120 of a highly thermally conductive material such as a layer of a graphite material or a layer of metal, and in some such embodiments the sheet 103 comprises a layer highly oriented pyrolytic graphite.

An apparatus 101 embodying the invention is shown in Fig. 1. The apparatus 101 comprises a heat sink means 102 which may be specifically provided for use as a heat sink and may be provided with features for dissipating heat to a fluid passing through or over the heat sink. For example, the heat sink means 102 may be a heat sink 102 comprising a block that defines passageways to allow a liquid to be passed through. The block may be formed of a material that is highly thermally conductive, such as aluminium or copper.

The apparatus 101 also comprises a sheet 103 having at least a first portion 104 positioned alongside the heat sink means 102. The first portion 104 may be in direct contact with the heat sink means 102, or may be spaced from it by another element that allows heat to flow from the sheet 103 to the heat sink means 102. For example, a second sheet may be positioned between the sheet 103 and the heat sink means 102.

The sheet 103 comprises a thermally conductive layer 120 of material that is thermally conductive along the plane of the sheet. For example, the thermally conductive layer 120 may comprise a graphite material, such as highly oriented pyrolytic graphite, or it may comprise a layer of metal, such as aluminium or copper. The apparatus 101 also comprises a plurality of battery cells 105 (in the present case two battery cells), that are positioned alongside a different second portion 108 of the sheet 103. More specifically, each battery cell

105 comprises an end wall 106 and a plurality of layers of electrode material 107, each of the layers 107 extending in a direction away from the end wall 106, and the end walls 106 are positioned alongside the second portion 108 of the sheet 103. The end walls 106 may be positioned in direct contact with the second portion 108 as shown in Fig. 1, or alternatively another element, such as a second sheet may be positioned between the end walls 106 and the sheet 103. For example, the thermally conductive layer 120 may have a thickness of 1 mm or less or in other embodiments may have a thickness of up to 8mm or more.

Although, for the purposes illustration, the apparatus 101 of Fig. 1 only comprises two battery cells, it should be understood that the apparatus 101 can be extended in the direction of arrow 150, i.e. in the direction along the line of battery cells 105, to include a larger number of battery cells. For example the apparatus 101 could comprise a line of 10 to 20 battery cells.

As shown, the battery cells 105 may be circular cylindrical battery cells having a jelly roll (or Swiss roll) design. Thus, the battery cells 105 may comprise layers of electrode material 107 that are coiled into a roughly cylindrical shape and located within a cylindrical can 109. The end wall 106 may form a part of the can 109 and provide a closed end to the can, as is the case in Fig. 1. In an alternative arrangement the end wall 106 may only partially close one end of the can 109 and may be electrically insulated from the can. In either case, the end wall 106 may provide one terminal of the battery cell. A second terminal 110 of opposite polarity may be provided at the opposite end of the cylinder. In an alternative embodiment, both terminals of the battery cell may be provided at one end that is opposite to the end wall

106 and to the location of the sheet 103.

In the apparatus shown in Fig. 1, the first portion 104 of the sheet 103 is substantially planar and it is positioned against a flat surface of the heat sink 102 to provide a relatively large area of contact. The second portion of the sheet 108 is also substantially planar to provide a good thermal contact with the end walls 106 of the battery cells 105. The sheet 103 may be provided with one or more folds between the first portion 104 and the second portion 108. Thus as shown in Fig. 1, the first portion 104 may extend up to a first fold 112, the second portion 108 may extend up to a second fold 113 and a third portion 114 of the sheet 103 may extend between the first and second folds 112 and 113. The folds 112 and 113 may each define a 90 degree bend in the sheet 103 so that the first portion 104 and the second portion 108 of the sheet 103 are parallel to each other but spaced apart. In alternative arrangements, other folds may be provided that result in the first portion 104 and the second portion 108 of the sheet 103 being parallel to each other but spaced apart. For example, the two folds may be greater than 90 degrees and less than 90 degrees by the same amount. For example, an 80 degree bend and a 100 degree bend. Alternatively a single 180 degree bend of relatively large radius of curvature may be provided, instead of two bends that add together to provide 180 degrees.

A support structure 115 (shown in dotted outline in Fig. 1) may be positioned below the second portion 108 of the sheet 103 so that areas of the sheet in contact with the battery cells 105 are sandwiched between the battery cells and the support structure 115. The support structure 115 may be arranged to support the weight of the battery cells 105 and also ensure that the sheet 103 is pressed against the end walls 106 of the battery cells to provide a good thermal contact.

The support structure 115 may be located between the first and second portions 104 and 108 of the sheet 103, as shown in Fig. 1, and the support structure 115 may be arranged to rest on the first portion 104 of the sheet 103 to press the sheet 103 against the heat sink 102 to ensure efficient heat transfer between the sheet 103 and the heat sink 102.

As will be described further below in regard to Fig. 2, the sheet 103 may be provided with holes or slots to enable an electrical conductor to pass through a hole or slot to provide electrical connection between the end wall 106 of a battery cell 105 and a busbar 111. The busbar 111 may be located within the support structure 115. The support structure 115 may be formed of an electrically insulating material so that it is able to electrically insulate the busbar 111 from other components of the apparatus 101 as required.

Although not shown in Fig. 1, it will be understood that in use electrical connections are made to the second electrodes 110 of the battery cells 105 in order to form an electrical circuit. For example, the second electrodes 110 of the battery cells 105 may all be connected to a second busbar (not shown in Fig. 1) so that the battery cells 105 of the apparatus 101 are connected in parallel.

During use, heat is electrically generated within the battery cells 105 and conducted along the layers of electrode material 107 to the end wall 106. The heat is conducted away from the battery cells 105 by the highly conductive sheet 103 which transfers the heat from the end walls 106 of the battery cells 105 to the heat sink 102. It has been found that by conducting heat away through the end walls 106, the radial temperature gradient within the battery cells 105 is minimized. Consequently, relatively large radial temperature gradients within each battery cell, which would increase cell ageing, are avoided.

As shown in Fig. 1, the second portion 108 of the sheet 103 that is arranged to be alongside the battery cells 105 may be arranged to extend only across the end walls 106 of the battery cells. That is, it does not extend over any other surfaces of the battery cells 105, such as along the side walls 116, which extend upwards from the end walls 106.

An alternative example apparatus 101A embodying the present invention is shown in Fig. 2. The apparatus 101A is similar to apparatus 101 of Fig. 1 in that it comprises a heat sink 102 and a sheet 103 having a first portion 104A in contact with the heat sink 102. The sheet 103 comprises a thermally conductive layer 120 of material that is thermally conductive along the plane of the sheet. Each one of a plurality of battery cells 105 has an end wall 106 in contact with a second portion 108 of the sheet 103 that is different to the first portion 104A. Each battery cell 105 has a plurality of layers of electrode material 107 and each of the layers 107 extends in a direction away from the end wall 106 of the battery cell 105.

The apparatus 101A differs from the apparatus 101 of Fig. 1 in that it comprises two rows of battery cells 105 instead of just one row. Thus, it has a first row comprising battery cells 105A and 105B and a second row comprising battery cells 105C and 105D. For illustration purposes, each of the two rows in Fig. 2 comprises just two battery cells. However, it will be understood that the apparatus 101A may be made longer in the direction of the rows of battery cells and each row may comprise more than two battery cells.

The apparatus 101A also differs in the form of its sheet 103. The sheet 103 of apparatus 101A is folded to form a channel having a central second portion 108, which is in contact with the battery cells 105, and two side portions 201A and 201B, extending from opposing sides of the central second portion 108, which are in contact with the heat sink 102. A busbar 111A for electrical connection to the end walls 106 of the battery cells 105 may extend within the channel formed by the sheet 103.

A part of the side portion 201A that is adjacent to an edge of the sheet 103 provides a first portion 104A that is located alongside the heat sink 102. Similarly a part of the side portion 201B that is adjacent to an opposite edge of the sheet 103 provides a further portion 104B that is located alongside the heat sink 102. The two side portions 201A and 201B perform similar functions to each other, and the further portion 104B performs a similar function to first portion 104A. In the present example, there is a gap between the first and further portions 104A and 104B of the sheet 103, but in an alternative example there is no such gap and the first and further portions 104A and 104B abut against each other.

The first portion 104A of the sheet 103 is substantially planar and it is positioned against a flat surface of the heat sink 102. The second portion 108 of the sheet 103 is also substantially planar to provide efficient heat transfer from the end walls 106 of the battery cells 105 to the sheet 103. The sheet 103 may be provided with one or more folds dividing the first portion 104A from the second portion 108. Thus as shown in Fig. 2, the first portion 104A may extend up to a first fold 112A, the second portion 108 may extend up to a second fold 113A and a third portion 114A of the sheet 103 may extend between the first and second folds 112A and 113A. Thus, in the present example, the first side portion 201A of the sheet 103 comprises the first portion 104A and the third portion 114A.

The folds 112A and 113A may each define a 90 degree bend in the sheet 103 so that the first portion 104A and the second portion 108 of the sheet 103 are parallel to each other but spaced apart.

The further portion 104B of the sheet 103 is also substantially planar and it is positioned against a flat surface of the heat sink 102. The sheet 103 may be provided with one or more folds dividing the further portion 104B from the second portion 108. Thus as shown in Fig. 2, the further portion 104B may extend up to a third fold 112B, the second portion 108 may extend up to a fourth fold 113B and a fourth portion 114B of the sheet 103 may extend between the third and fourth folds 112B and 113B. Thus, in the present example, the second side portion 201B of the sheet 103 comprises the further portion 104B and the fourth portion 114B.

The folds 112B and 113B may also each define a 90 degree bend in the sheet 103 so that the further portion 104B and the second portion 108 of the sheet 103 are parallel to each other and spaced apart.

It may be noted that each of the battery cells 105 is adjacent to one of the folds, 113A or 113B, at one edge of the second portion 108 or the opposite edge. Consequently, for each of the battery cells 105, a respective area of the sheet 103 extends between the respective battery cell 105 and the heat sink means 102 that is free from other battery cells. For this area the respective battery cell is the nearest battery cell to all points within the area. For example, an area 202 of the sheet 103 extends from the battery cell 105B across the second portion 108, around the second fold 113A, across the third portion 114A, around the first fold 112A and across the first portion 104A, which is in contact with the heat sink 102. For all points within the area 202 extending between battery cell 105B and the heat sink 102, the battery cell 105 is the nearest battery cell.

It will be understood that the fourth portion 114B and further portion 104B of the sheet 103 provide a similar function as the third portion 114A and first portion 104A respectively. Thus, for the battery cells 105C and 105D there is an area of the sheet 103, similar to area 202, but which extends across the second portion 108, around the fourth fold 113B, across the fourth portion 114B, around the third fold 112B and across the further portion 104B, which is in contact with the heat sink 102.

The apparatus 101A may also comprise a support structure 115A positioned below the second portion 108 of the sheet 103 so that areas of the sheet in contact with the battery cells 105 are sandwiched between the battery cells and the support structure 115A. The support structure may be arranged to support the weight of the battery cells 105 and also ensure that the sheet 103 is pressed against the end walls 106 of the battery cells to provide a good thermal contact.

The support structure 115A may be located above the first portion 104A and the further portion 104B and below the second portion 108 of the sheet 103, as shown in Fig. 2. The support structure 115A may be arranged to rest on the first portion 104A and the further portion 104B of the sheet 103 to press the first portion 104A and the further portion 104B of the sheet 103 against the heat sink 102 to ensure a good thermal contact between the sheet and the heat sink.

The busbar 111A may be located within the support structure 115A, which is formed of an electrically insulating material so that the support structure 115A is able to electrically insulate the busbar 111A from other components of the apparatus 101A as required.

A more detailed cross-sectional view of the apparatus 101A is shown in Fig. 3. The cross section of Fig. 3 is along a vertical plane through the battery cell 105A and perpendicular to the direction of a row of battery cells.

As mentioned above, the layers of electrode material 107 extend along the battery cells 105, such as battery cell 105A as shown in Fig. 3. In Fig. 3, the battery cells 105 are cylindrical battery cells having a circular cross-section and a central axis 320 that extends perpendicularly away from the end wall 106 and the second portion 108 of the sheet. In an alternative embodiment the battery cells 105 may be prismatic battery cells having a noncircular cross-section, but, like the present embodiment, the layers of electrode material of the cells extend away from an end wall 106 that is located alongside the thermally conductive sheet 103.

The materials forming the layers of electrodes 107 of the battery cells 105 are relatively good thermal conductors, for example, when compared to the electrolyte material between the layers 107. Therefore, the layers 107 of electrode material are able to efficiently conduct heat down towards the end walls 106 of the battery cells 105 during use. The heat is then transferred to the sheet 103 that is in contact with the end walls 106 and conducted through the sheet to the heat sink 102.

As shown in Fig. 3, for each battery cell 105, the sheet 103 may be provided with a hole 301 positioned against the respective end wall 106 to allow the passage of an electrical conductor 302 providing connection between the end wall 106 and the busbar 111 A. The electrical conductor 302 may be a metal wire that is welded to the end wall 106 and welded to the busbar 111A.

The support structure 115A may be provided with a cavity 303 beneath each of the battery cells 105 and adjacent to the busbar 111A to allow the passage of the electrical conductor 302. The support structure 115A may also be provided with a removable lower cover 304, that, when removed, allows access to the busbar 111A and cavities 303 to enable the electrical conductor 302 to be connected (for example by welding) to the busbar 111A during manufacture.

As mentioned above, the sheet 103 may comprise a thermally conductive layer 120 of highly thermally conductive material, and the thermally conductive material may also be electrically conductive. However, in addition, the sheet 103 may comprise a layer 307 of electrically insulating material that extends across a first face of the thermally conductive layer 120. In the present embodiment only one electrically insulating layer 307 extends across a face of the thermally conductive layer 120. However, in an alternative embodiment, a second layer of electrically insulating material is also provided on the thermally conductive layer 120 on the opposite face to the first face. That is, the thermally conductive layer 120 may be sandwiched between two outer electrically insulating layers 307.

The layer 307 of electrically insulating material may be disposed between the thermally conductive layer 120, which may also be electrically conductive, and the end walls 106 of the battery cells 105 to prevent the thermally conductive layer 120 from coming directly into contact with the end walls 106 of the battery cells 105. In this way the formation of an electrically conductive path from the end walls 106 through the thermally conductive layer 120 is prevented.

Portions of the layer 307 of electrically insulating material, corresponding to the first portion 104A and the further portion 104B, may also be disposed between the thermally conductive layer 120, which may also be electrically conductive, and the heat sink means, to prevent the electrically conductive material 120 from electrically contacting the heat sink means.

The layer 307 of insulating material may be formed as a coating on the thermally conductive layer 120. For example the insulating material 307 may be a polyester coating formed on a conductive metal layer 120. Alternatively the thermally conductive layer 120 may be formed as a coating on the insulating material layer 307. In an example, the sheet 103 comprises a pyrolytic graphite sheet comprising a highly oriented graphite polymer film and the one or two layers 307 of insulating material comprise a polymer such as a polyester.

In an alternative embodiment, the thermally conductive layer 120 and the layer 307 of insulating material may be provided as two separate sheets that are positioned face to face with any necessary holes in the thermally conductive layer 120 aligned with similar holes in the insulating layer 307.

The sheet 103 may also define additional holes 308 to allow parts 309 of the support structure 115A to extend upwards past the plane of the second portion 108. The parts 309 may be in the form of posts that are positioned to define the locations in which the battery cells 105 may be positioned and to retain the battery cells 105, such as cells 105A and 105C, at those locations.

As shown in Fig. 3, the heat sink 102 may comprise a block of material defining internal channels 310 for the passage of a liquid coolant to enable heat to be removed from the heat sink.

Although the heat sink 102 is generally used to take heat away from the battery cells 105 via the sheet 103, it is also envisaged that the battery cells 105 may be warmed when necessary by providing heat from the heat sink via the sheet 103. The heat sink 102 may have an internal pipe (not shown) circulating a fluid which may serve as a means of heating or cooling the heat sink 102 which then could heat or cool the battery cells 105.

A second busbar 111B may be provided for connection to the terminals 110 of the battery cells by electrical conductors 302A, so that the apparatus 101A forms a battery, or a part of a battery, in which the battery cells 105 are connected in parallel. The battery may be connected in parallel and/or in series with other similar batteries to provide a battery having a required voltage and capable of providing a required electrical current. The battery may be located within a vehicle and used to store power used for an electrical system of the vehicle.

A plan view of the support structure 115A is shown in Fig. 4A and an end view of the support structure 115A is shown in Fig. 4B.

The support structure 115A has an upper surface 401 and a plurality of posts 309 which extend upwards from the upper surface 401. The posts 309 are positioned so that they extend just outside of the intended locations of the battery cells 105, which are shown in dotted outline 402 in Fig. 4A. The support structure 115A also defines the cavities 303 that enable the passage of the conductors 302 (shown in Fig. 3) between the battery cells 105 and the busbar 111 A. In the present example the cavities are cylindrical (having a circular cross-section) and arranged to be concentric with the battery cells, but it will be understood that other shaped cavities may be used, provided the cavities enable the passage of the conductors 302 and provide access to enable the conductors to be attached to the busbar 111A during assembly of the apparatus. Thus, the cavities 303 extend from the upper external surface 401 of the support structure down to a hole 403 configured to receive the busbar 111 A.

As mentioned previously, the support structure 115A may comprise a lower cover 304 which, when removed from a main part 405 of the support structure 115A, provides access to the cavities 303 and busbar 111 A.

The sheet 103 configured for assembly to the support structure 115A is shown in the plan view of Fig. 5. The sheet 103 may be rectangular and provided with a first plurality of holes 301 to enable the passage of the electrical conductors 302 from the battery cells 105 to the busbar 111 A. The sheet may be also provided with a second plurality of holes 308 to enable the passage of the posts 309 (shown in Fig.3), which extend upwards from the upper surface 401 of the support structure 115A. Lines where folds 112A, 113A, 112B and 113B may be made to define the first portion 104A, further portion 104B and the second portion 108 are also shown in Fig. 5.

To assemble the apparatus 101 the sheet 103 is positioned on the upper surface 401 of the support structure 115A by locating the posts 309 in the holes 308. When positioning the sheet 103, the insulating layer 307 is positioned uppermost so that it will be located between the battery cells and the thermally conductive layer 120 of the sheet.

The electrical conductors 302 may each be attached to a respective battery cell 105, for example, by welding, and the electrical conductors 302 each located through a respective one of the holes 301 in the sheet. The busbar 111A may be positioned within the hole 403 and the electrical conductors 302 may then be attached to the busbar 111 A, for example by welding. The lower cover 304 may be located on the main part 405 of the support structure 115A to retain the busbar 111A in position. The sheet 103 may be folded at folds 113A, 113B, 112A and 112B, to at least partially enclose the support structure 115A, and then this assembly may be located on a heat sink 102. The heat sink may be of sufficient size to enable a plurality of other similar assemblies to be located upon it.

Typically, the terminals 110 opposite to the end walls 106 of the battery cells 105 are then similarly electrically connected to another busbar (such as 111B, shown in Fig. 3) so that the battery cells 105 form a battery, or a part of a battery, suitable for use in a vehicle.

A vehicle 601 is shown schematically in Fig. 6. The vehicle 601 comprises an electrical system 602 that includes a battery 603, a generator 604 and a power train 605 comprising an electric motor 606. The vehicle may be an electrically powered vehicle or it may be a hybrid vehicle in which the power train also comprises an internal combustion engine. The battery 603 comprises a plurality of apparatuses 101 and/or 101A that are electrically connected in parallel and/or in series as required in order to provide the necessary voltage and currents for the motor 606. The battery cells may be rechargeable battery cells and arranged to be recharged by the operation of the generator 604 and/or an external electrical power supply.

A method 700 of assembling an apparatus is shown in the flowchart of Fig. 7. At block 701, a plurality of battery cells, such as battery cells 105, is positioned so that an end wall of each battery cell is positioned alongside a second portion of a sheet, such as second portion 108 of sheet 103. As described above, the battery cells 105 may be positioned with the end walls 106 in direct contact with the sheet 103, or alternatively a thin electrically insulating sheet may be provided between the sheet and the end walls. The battery cells each comprise a plurality of layers of electrode material (such as layers 107), and each of the layers of electrode material extends in a direction from the respective end wall. The sheet comprises a layer (such as layer 120) of material that is thermally conductive along the plane of the sheet.

In an example, the sheet comprises a layer of electrically conductive material and a layer of electrically insulating material (such as layer 307), and the positioning the plurality of battery cells at block 701 comprises positioning battery cells in direct contact with the sheet so that the layer of electrically insulating material is between the end wall of each of the battery cells and the layer of electrically conductive material.

The battery cells each have one or more side walls extending from the end wall and, in an example of method 700, the battery cells are positioned so that the sheet is not in contact with the one or more side walls.

At block 702, at least one first portion of the sheet (such as first portion 104 or 104A or further portion 104B) that is different to the second portion is brought into contact with a heat sink means.

In examples of the method 700, at block 701 the battery cells are arranged in rows as described above in respect of Figs. 1 and 2. The battery cells are therefore positioned on the sheet to form an array that is no more than two rows wide, so that, for each battery cell, a respective area of the sheet between the respective battery cell and the heat sink means is free of other battery cells, and the respective battery cell is the nearest battery cell to all points within the area. Thus, for each battery cell, the sheet effectively provides a dedicated path for heat flow from the battery cell to the heat sink means.

A second method 800 of assembling an apparatus, such as that shown in Fig. 2, is shown in the flowchart of Fig. 8. At block 801, a thermally conductive sheet is positioned on a support structure. As described above, the sheet may define a plurality of holes that are configured to receive posts of the support structure, and therefore this process may comprise locating the posts within the holes of the sheet. At block 802, a plurality of battery cells is positioned so that end walls of the battery cells are located alongside the sheet. As described above, the end walls may be positioned with the end walls in direct contact with the sheet, or alternatively a thin electrically insulating sheet may be provided between the sheet and the end walls. The process at block 802 may be the same as that at block 701 of Fig. 7.

At block 803, for each one of the battery cells, an electrical conductor is located through a respective hole or slot formed in the sheet and the battery cell is connected to a busbar via the electrical conductor. This may be achieved by welding a wire to the end wall of each of the battery cells in advance of locating the wire through a respective hole in the sheet and welding the wire to the busbar.

At block 804 the sheet is folded to form a channel having a central portion on which the battery cells are located and two side portions extending from opposing sides of the central channel. In this way, the support structure and the busbar may be located within the channel formed by the sheet. In an alternative method, the sheet is only folded to form one side portion as shown in Fig. 1. However, in this case the array of battery cells located against the sheet is restricted to just one row of battery cells.

At block 805, at least a first portion of the sheet that is different to the central portion (the second portion) is positioned alongside a heat sink means. The process at block 805 may therefore be the same as the process at block 702 of Fig. 7. In an example, parts of each of the two side portions of the sheet are positioned alongside a heat sink means, and in some examples the portions of the sheet that are positioned alongside the heat sink means are positioned to be in direct contact with the heat sink means. For example, in the example of Fig. 2, the first portion 104A of the first side portion 201A of the sheet 103 and the further portion 104B of the second side portion 201B are positioned alongside the heat sink 102, and the battery cells are located on the second central portion 108 of the sheet 103.

The illustration of a particular order to the blocks of Figs. 7 and 8 does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some blocks of the methods to be omitted.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. An apparatus comprising: a heat sink means;

a sheet having at least a first portion positioned alongside the heat sink means, the sheet comprising a layer of material that is thermally conductive along the plane of the sheet;

a plurality of battery cells, each battery cell having an end wall and a plurality of layers of electrode material, each of the layers of electrode material extending in a direction away from the end wall, wherein the end walls of the battery cells are positioned alongside a different second portion of the sheet.

2. An apparatus according to claim 1, wherein the sheet comprises a layer of graphite material or a layer of metal.

3. An apparatus according to claim 1, wherein the sheet comprises a layer of highly oriented pyrolytic graphite.

4. An apparatus according to any one of claims 1 to 3, wherein the sheet of thermally conductive material has a thickness of less than 8mm.

5. An apparatus according to any one of claims 1 to 4, wherein the sheet of thermally conductive material has a thickness of less than 1 mm.

6. An apparatus according to any one of claims 1 to 5, wherein the sheet of thermally conductive material has a thickness in the range of 0.01 and 0.1mm.

7. An apparatus according to any one of claims 1 to 3, wherein the sheet of thermally conductive material has a thickness of 0.1mm.

8. An apparatus according to any one of claims 1 to 7, wherein the sheet comprises a layer of electrically conductive material and the apparatus further comprises a layer of electrically insulating material disposed between the layer of electrically conductive material and the end walls of the battery cells.

9. An apparatus according to any one of claims 1 to 8, wherein the layer of electrically insulating material provides a coating on the layer of electrically conductive material.

10. An apparatus according to any one of claims 1 to 9, wherein the sheet defines a plurality of first holes, each of the first holes corresponding to a respective one of the battery cells, and the apparatus further comprises a busbar and a plurality of electrical conductors, each electrical conductor being located through a respective one of the first holes and connecting the busbar to the respective battery cell.

11. An apparatus according to claim 10, wherein the sheet comprises at least one fold separating the first portion from the second portion, so that the sheet extends from the battery cells around the busbar to the heat sink means.

12. An apparatus according to claim 10 or claim 11, wherein the sheet comprises folds to provide a channel having a central second portion and two side portion extending from opposing sides of the central second portion, the battery cells are located alongside the central second portion, the heat sink means is located alongside the side portions and the busbar extends within the channel.

13. An apparatus according to any one of claims 1 to 12, wherein the battery cells located alongside the sheet form an array that is no more than two rows wide.

14. An apparatus according to any one of claims 1 to 13, wherein for each of the battery cells, a respective area of the sheet extending between the respective battery cell and the heat sink means is free from other battery cells, and the respective battery cell is the nearest battery cell to all points within the area.

15. An apparatus according to any one of claims 1 to 14, wherein the heat sink means comprises a heat sink defining channels for the passage of fluid to enable heat to be removed from the heat sink.

16. An apparatus according to any one of claims 1 to 15, wherein the battery cells are cylindrical battery cells each having a central axis that extends away from the second portion of the sheet.

17. An electrical system of a vehicle, the electrical system comprising an apparatus according to any one of the preceding claims and a motor configured to receive electrical energy from the battery cells of the apparatus.

18. A vehicle comprising an apparatus according to any one of claims 1 to 16 or an electrical system according to claim 17.

19. A method of assembling a plurality of battery cells, the method comprising:

positioning a plurality of battery cells, each battery cell having an end wall and a plurality of layers of electrode material that extend away from the end wall, so that the end walls are positioned alongside a second portion of a sheet, the sheet comprising a layer of material that is thermally conductive along the plane of the sheet; and positioning at least a different first portion of the sheet alongside a heat sink means.

20. A method according to claim 19, wherein the sheet comprises a layer of electrically conductive material and a layer of electrically insulating material, and the positioning the plurality of battery cells comprises positioning the layer of electrically insulating material between the end walls of the plurality of battery cells and the layer of electrically conductive material.

21. A method according to claim 19 or claim 20, wherein the sheet defines a plurality of first holes, and the method comprises positioning the end wall of each of the plurality of battery cells against a respective one of the first holes and connecting each of the end walls to a busbar by a respective electrical conductor located through the respective first hole.

22. A method according to claim 21, wherein the method comprises folding the sheet so that the sheet extends from the battery cells around the busbar to the heat sink means.

23. A method according to any one of claims 19 to 22, wherein the method comprises folding the sheet around a support structure and supporting the support structure on the heat sink means with the at least first portion of the sheet located between the support structure and the heat sink means.

24. A method according to any one of claims 19 to 23, wherein the sheet comprises folds to form a channel having a central portion and two side portion extending from opposing sides of the central portion, and the method comprises positioning the battery cells to be in contact with the central portion, and bringing the heat sink means into contact with the side portions so that the busbar extends within the channel.

25. A method according to any one of claims 19 to 24, wherein the battery cells are positioned on the sheet to form an array that is no more than two rows wide.

26. A method according to any one of claims 19 to 25, wherein the battery cells each have one or more side walls extending from the end wall and the battery cells are positioned so that the sheet is not in contact with the one or more side walls.

27. A sheet comprising a layer of material that is thermally conductive along the plane of the sheet, wherein the sheet comprises:

at least a first portion positioned alongside a heat sink means; and a different second portion of the sheet positioned alongside an end wall of each one of a plurality battery cells, the end wall of each battery cell being positioned such that a plurality of layers of electrode material within the battery cell extend in a direction away from the end wall.

28. An apparatus, as described herein with reference to the accompanying figures.

29. An electrical system as described herein with reference to the accompanying figures.

30. A vehicle as described herein with reference to the accompanying figures.

31. A method as described herein with reference to the accompanying figures.

Intellectual

Property

Office

Application No: GB1611727.7 Examiner: Dr Lyndon Ellis