WO2015075460A1

WO2015075460A1 - Battery pack

Info

Publication number: WO2015075460A1
Application number: PCT/GB2014/053440
Authority: WO
Inventors: Alexander SCHEY; Toby SCHULZ
Original assignee: Vantage Power Limited
Priority date: 2013-11-20
Filing date: 2014-11-20
Publication date: 2015-05-28
Also published as: GB201320491D0; GB2520929A

Abstract

The present invention relates to a battery pack (400) having a modular construction, components thereof, methods of manufacturing battery packs (400), and methods of installing a battery pack (400) in a device. A battery module (200) for a battery is provided, comprising an elongate sleeve (20) enclosing a stack of cell blocks (100). Each cell block (100) comprises first and second conductive end plates (12a, 12b) and a plurality of cells (10). Each cell (10) extends between the first and second end plates (12a, 12b).

Description

Battery Pack

The present invention relates to a battery pack having a modular construction, components thereof, methods of

manufacturing battery packs, and methods of installing a battery pack in a device.

Conventional battery packs are typically developed

specifically for applications where space requirements and limitations are known.

There is a need in the art for a battery pack having a modular construction to provide flexibility in fitting a battery pack to spaces whereby the requirements and limitations vary between applications.

According to a first aspect of the invention, there is provided a battery module defined by claim 1.

According to a second aspect of the invention, there is provided a method of manufacturing a battery defined by claim 28.

According to a third aspect of the invention, there is provided a method of manufacturing a battery defined by claim 33.

According to a fourth aspect of the invention, there is provided a battery module defined by claim 34.

Such a battery module can be easily manufactured to required parameters (including both the electrical requirements of the battery and also the physical requirements of size and shape) by choosing the number of cells per cell block and the length of the sleeve. Advantageously, the sleeve may be an off-the- shelf item such as a simple PVC pipe that is simply cut to the length required. The sleeve or tube may have any cross- sectional shape. However, the preferred embodiments disclosed herein utilise sleeves/tubes having a circular cross-section since this is available on a large scale and is inexpensive.

For a better understanding of the invention and to show how the same may be put into effect reference is now made, by way of example only, to the accompanying drawings in which:

Figure 1A shows a perspective view of a cell block;

Figure IB shows a plan view of the cell block of Figure 1A;

Figure 1C shows an exploded view of the cell block of Figure

1A;

Figure 2A shows an exploded view of a battery module having cell blocks of the type shown in Figures 1A and IB;

Figure 2B shows a cross-sectional view of the battery module of Figure 2B; and

Figure 3 shows a close-up cross-sectional view of the end of the battery module of Figures 2A and 2B;

Figure 4 shows a perspective view of a battery having a plurality of battery modules of the type shown in Figures 2A and 2B;

Figure 5A shows an exploded view of a battery having a plurality of battery modules of the type shown in Figures 2A and 2B; and

Figure 5B shows a close-up view of a preferred terminal end plate .

Figures 1A and IB show a cell block 100. A cell block 100 comprises a plurality of cells 10, each extending between conductive end plates 12a, 12b. As described below (e.g. with reference to Figure 2A) , multiple cell blocks 10 may be introduced into a sleeve 20 to form a battery module 200 (see Figure 4 ) .

Preferably, the sleeve 20 comprises or is formed from one or more non-conductive materials, such as PVC .

The sleeve 20 may be manufactured by extrusion. A desired length of the extruded part may be used for the sleeve 20. For example, the extruded part may be simply cut to the desired length. Advantageously, such a method allows sleeves for any length of battery module to be made using a single extrusion process and simply cut to the length required.

First end plate 12a is in communication with the anode of each cell 10 of the cell block 100, while second end plate 12b is in communication with the cathode of each cell 10 of the cell block 100. In this way, the plurality of cells 10 of each cell block 100 are connected in parallel between the end plates 12a, 12b.

The end plates 12 of each cell block 100 contact each of the cells 10 of the cell block 100, and have apertures 15 through which coolant may flow.

Preferably, the end plates 12 comprise or are made of a metal, such as nickel, aluminium, or copper. Preferably, the end plates 12 are welded (for example arc welded or resistance welded) to the cells 10.

Within each cell block the cells 10 are preferably spaced apart so as not to contact. However, the cells 10 are

preferably closely packed. Spaces between the cells 100 may be aligned with the apertures 15 in the end plates 12 so that coolant can flow unimpeded through the passages in each cell block 10 defined by the cells 10 and aligned with the apertures 15.

In each cell block 100, the outermost cells 10 define a perimeter of the cell block 100 (in plan view) that preferably closely fits the interior cross-section of the sleeve 20.

Such a close fit can substantially prevent the cell block 10 from moving perpendicularly to the longitudinal axis of the sleeve 20. However, each cell block 10 is preferably not directly attached to the sleeve 20 and thus may be slidable within the sleeve 20 along its axis.

The cells 10 are preferably cylindrical in shape. With reference to Figure 1C, the cells 10 preferably have a first terminal 8 (anode or cathode) forming a portion of the first end of the cylinder and a second terminal 9 (cathode or anode, respectively) that forms the second end of the cylinder and extends from the second end around the body of the cell 10 to the first end. It may be the case that the second terminal 9 also forms the peripheral area 7 surrounding the portion of the first end that defines the first terminal 8. Thus

typically the terminals of a cell 10 may be separated by just a few millimetres.

Since the terminals 7, 8 and 9 of each cell 10 are exposed and can be very close together, it may be difficult to attach a conductive end plate 12 to a plurality of cells 10 without short-circuiting the cell 10. It is therefore preferable that each cell block 100 comprises a non-conductive gasket 6 between the first terminal 8 and the peripheral area 7 of each of the plurality of cells 10 and the end plate 12a. The non- conductive gasket 6 may be flexible. The non-conductive gasket 6 (for example, formed of rubber) may be provided with holes corresponding to any holes 13 or apertures 15 in the end plate 12a. The non-conductive gasket 6 may have holes 5 through which the end plate 12a may contact the first

terminals 8 of the cells 10. The holes 5 can be sized to ensure that there is a sufficient contact area between the end plate 12a and the first terminal 8 of the cells 10 for good conductivity, but that there is no contact between the end plate 12a and the second terminal of the cell 10, including the periphery 7.

Preferably, the terminals of the cells 10 are not covered by a sleeve or housing individual to that cell 10. The cells 10 are preferably secondary electrochemical cells, such as lithium iron phosphate cells.

Each cell block 100 may also comprise a circuit board 16. The circuit board 16 may measure the voltage across each cell block 100. The circuit board 16 may include a temperature sensor, such as a thermistor. The circuit board 16 may also include other componentry in order to change the charging characteristics of the cell block 100.

Preferably, a tab is provided extending perpendicular to each end plate 12. The circuit boards 16 may be attached at each end to the tab (preferably, using rivets) .

As shown in Figures 2A and 2B, a plurality of cell blocks 10 may be stacked to form a cell stack 150. One or more cell stacks 150 may be slidably held within a sleeve 20 between two opposing sleeve closures 22.

Each end plate 12 may also have one or more alignment holes 13 (shown in Figures 1A and IB) . One or more alignment rods 14 (two are depicted) may pass through the alignment hole(s) 13 of multiple cell blocks 100 to maintain rotational alignment of the cell blocks 100 relative to each other. Preferably, the alignment rods 14 are not conductive. More preferably, the alignment rods 14 are PVC . Optionally, bolts may be used to lock each cell stack 150 together.

In preferred embodiments, although the cell blocks 100 may closely fit the interior cross-section of the sleeve 20, a gap may be provided such that the cell block 100 does not contact the sleeve 20. In such cases, radial locators 18 may be located between one or more of the cell blocks 100 aligned by each alignment rod 14. The radial locators 18 may abut interior surface of the sleeve 20 so as to prevent any lateral movement of the battery modules 100. The radial locators 18 may be formed as plates with radial extensions formed thereon and apertures to allow the passage of cooling fluid, which apertures align with the apertures 15 in the end plates 15 and the corresponding coolant passages defined in the cells 10. The radial locators 18 can additionally provide rigidity to each cell stack 150. Such radial locators 18 may comprise conductive material.

As shown in Figure 3, sleeve closures 22 are preferably slidably held within the sleeve 20. Preferably, the sleeve closures 22 form a fluid tight seal with the sleeve 20.

Preferably, the sleeve closures 22 form an interference fit with the sleeve 20.

One or more O-rings 23 may be provided to prevent fluid from passing between the sleeve closure 22 and the sleeve 20.

The sleeve closures 22 are preferably in the form of plugs. The plugs are insertable into the ends of the sleeve 20.

The sleeve closures 22 may be provided with coolant ports 25 connectable to a source of coolant. A flow of coolant through the battery module 200 may be provided between coolant ports 25 provided in sleeve closures 22 at either end of the sleeve 20 of a battery module 200. Preferably, the coolant ports 25 are made of non-conducting material.

Optionally, a wiring port 27 may be provided in the sleeve closure 22 at one or both ends of each battery module 200, through which wiring in communication with each of the

circuits 16 of the cell blocks 100 may pass. The wiring ports 27 may be sealed to prevent unwanted egress of coolant from the battery module 200.

Optionally, threaded fixing holes 28 may be provided to allow the sleeve to be affixed to another structure.

Since the cell blocks 100 and the sleeve closures 22 are slidable within the sleeve 20, a good electrical contact can be obtained between abutting cell blocks 100 by applying a force to the sleeve closures 22 to slightly compress the cell blocks 100 therebetween. It is preferable that the sleeve closures 22 extend axially outwardly from the end of the sleeve 20.

However, in some embodiments, the sleeve closures 22 may be entirely within the sleeve 20 (i.e. not protruding beyond the end of the sleeve) . In such embodiments, the end plates 320 (described below) may have protrusions extending therefrom into one or more sleeves 20 for connection with one or more sleeve closures 22, or spacers may be provided between the end plates 320 and sleeve closures 22 to attach the end plates 320 to one or more sleeve closures 22.

The sleeve closures 22 may comprise conductive material for contacting the end of a cell stack 150. Thus, in each cell block 100 (see Figure 1A) the cells 10 are connected in parallel between the conductive end plates 12a, 12b, while in each cell stack 150 (see Figure 2B) the cell blocks 100 are connected in series (either directly or via a conductive radial locators 18); and in each battery pack 400 the battery modules are connected in parallel and/or series. The sleeve closures 22 can provide terminals of each battery module 200.

Figure 4 shows a combined module 300. A combined module 300 is defined by the one or more battery modules 200 and terminal plates 320.

The combined module 300 comprises a pair of terminal plates 320 sandwiching several battery modules 200 between end plates 320. The alignment plates 315 can also provide support to the battery modules 200 between the end plates 320. The terminal plates 320 may be held together by one or more ties 310.

Preferably, ties 310 are rods passing through the terminal plates 320. Ties 310 may be provided with tightening nuts 312. The tension in ties 310 can be adjusted (for example, by tightening of each of the tightening nuts 312) to thereby ensure that each battery module 200 is subjected to the correct amount of compression. A slight compression of each battery module 200 can provide a good electrical connection between each cell block 100, between the cell stacks 150 and the sleeve closures 22, and between the sleeve closures and the alignment plates 315 and terminal plates 320.

Terminal plates 320 may be fixed to the sleeve closures 22, for example by bolts extending into the fixing holes 28.

A preferred form of a terminal plate 320 is shown in Figures 5A and 5B. A connection plate 322 may include a non-conductive body having apertures 341 providing a space for conductive

connectors 335 such that the non-conductive body defines the way battery modules 200 may be interconnected using connectors 335 to thereby prevent unwanted electrical contact with other components .

The connection plates 322 are preferably comprise a non- conductive material, such as a plastic.

Figure 5C shows how the connectors 335 can be affixed to the sleeve closures of each battery module using fixing means (e.g. bolts) . The apertures 341 in each connection plate 322 are complementary in shape with at least a portion of a connector 335. Thus, it is not possible to inadvertently connect the connectors 335 to the battery modules 200

incorrectly .

Only a small number of connection plates 322 are needed to define the many ways in which the battery modules 200 may be connected together. For example, the pair of connection plates 322 at the ends of the four battery modules 200 connect the battery modules 200 in series.

The non-conductive body preferably comprises or is made from a plastic .

Optionally, an insulating sheet 324 may be sandwiched between the connection plate 322 and a housing plate 326.

Each of the insulating sheet 324, the connection plate 322, and the housing plate 326 may comprise holes corresponding to any coolant port 25, wiring port 27, and/or bolt holes. The housing plate 326 may support one or more coolant conduits 330 (see Figure 4) in communication with one or more of the coolant ports 25. Preferably, the coolant conduits 330 are formed integrally with the housing plate 326.

Housing plates 326 at either end of the one or more battery modules 200 may be connected together using ties 310.

Housing plates 326 preferably comprise or are formed of steel.

The module connection plate 322 may comprise a plurality of connection plates 322a, 322b, 322c, 322d. Each connection plate 322a-322b may support one or more battery modules 200 and define how they are interconnected. Preferably, each connection plate 322a-322d may support four or more battery modules 200.

By forming a module connection plate 322 using a plurality of connection plates 322a-322d, a large range of end terminals can be designed using only a small number of standard parts coupled in different arrangements.

Preferably, if the combined module 300 comprises a plurality of battery modules 200 having long sleeves 20, the alignment plates 315 are provided to support the sleeves 20 at one or more locations along their lengths. Each alignment plate 315 may have the same shape as the terminal plates 320, but have holes through which the sleeves 20 may be inserted.

A battery pack 400 which comprises the combined module 300 described above, and may comprise the coolant conduits 330 (for example, in the form of piping or hosing) provided on each terminal plate 320. The coolant conduits 330 may

communicate with the coolant ports 25 of the sleeve closures in contact with that terminal plate 320. Preferably, the coolant conduits 330 are arranged so that fluid passes through each battery module 200 in parallel. However, embodiments are envisaged in which other flows of coolant are provided.

The battery pack 400 may also include: a coolant pump for circulating coolant within the battery 200; and a heat pump for cooling the coolant.

The flow of coolant through the battery modules 200 allows direct contact between each individual cell 10 and the

coolant. Accordingly, a non-conductive coolant is used.

Preferably, the coolant is non-flammable. For example, the coolant may comprise transformer oil.

When each cell block 100 includes a circuit 14 and each circuit 14 includes a temperature sensor, it is possible to monitor the temperature of each cell block 100. It is also possible to monitor the temperature gradient along each cell block 100. This information can be used to identify whether the flow of coolant should be increased for one or more battery modules 200.

Battery packs 400 in the form described above can be

advantageously retrofitted to devices largely irrespective of the available space within the device. For example, a battery pack 400 may be retrofitted to a vehicle such as an automobile (for example, a bus) .

A method of retrofitting the battery pack 400 comprises identifying one or more cavities in the device.

A cavity will have a cross-section and a length. First and second terminal plates 320 for either end of the battery pack can be manufactured such that they fit within the cross-section of the cavity. Since the battery modules 200 have only a small cross-sectional area as compared with the terminal plates 320, the terminal plates 320 may have various shapes (i.e. any shape that can encompass repeated cross- sectional foot-prints of the sleeve 20) .

Preferably, the terminal plates 320 are shaped so as to be complementary with the cavity. For example, Figure 4 shows L- shaped terminal plates 320, which would fit within an L-shaped cavity .

One or more sleeves 20 can be manufactured with a length that fits within the length of the cavity.

One or more battery modules 200 may be made by sliding a cell stack 150 into the sleeve. The number of cell blocks 100 in the cell stack 250 can be chosen to fit within the available length of the sleeve 20 incorporating a sleeve closure 22 at either end.

The first and second terminal plates 320 can be fit to

respective ends of the battery module 200.

If required, a plurality of battery modules 200 may be

provided. The number of battery modules 200 in the battery pack 400 can be chosen to fit within the available area of the terminal plates 320.

The assembled battery pack 400 may then be installed within the cavity. The installation of the battery pack 400 may form part of a method of retrofitting an additional battery pack to a vehicle to supplement an existing battery.

Moreover, the installation of the battery pack 400 may form part of a method of retrofitting an electric or hybrid drive system to a vehicle (for example a bus) in place of a

conventional internal combustion engine. The internal combustion engine may be removed from the vehicle to leave a cavity. Once the space required for the components of the replacement system has been considered, the battery pack 400 may be designed (i.e., the shape of the terminal plates 320 and the length of the sleeves 20 defined) to fit within the remaining cavity.

Claims

CLAIMS :

1. A battery module for a battery, comprising:

an elongate sleeve enclosing a stack of cell blocks, wherein each cell block comprises:

first and second conductive end plates; and

a plurality of cells, each cell extending between the first and second end plates.

2. The battery module of claim 1, wherein an end plate of one cell block directly contacts an end plate of a second cell block .

3. The battery module of any preceding claim, further comprising means for maintaining rotational alignment of a plurality of cell blocks within the sleeve.

4. The battery module of claim 3, wherein the means for maintaining rotational alignment of the cell blocks within the sleeve comprises one or more rods extending through the end plates .

5. The battery module of any preceding claim, further comprising means for maintaining a gap between the cell blocks and the sleeve.

6. The battery module of claim 5, wherein the means for maintaining a gap comprises one or more radial locators abutting the interior surface of the sleeve.

7. The battery module of claim 6, wherein each radial locator comprises a plate having a plurality of radial

extensions .

8. The battery module of any preceding claim, wherein the plurality of cells are laid out between the end plates to define an outer perimeter of the cell block that closely fits the interior cross-section of the sleeve.

9. The battery module of any preceding claim, wherein each cell block comprises a temperature sensor and a sensor circuit associated therewith.

10. The battery module of any preceding claim, wherein each cell block has a voltage sensor circuit arranged to measure the voltage difference between the end plates.

11. The battery module of claim 9 or claim 10, wherein the sensor circuit extends between the two end plates of the cell.

12. The battery module of claim 11, wherein the sensor circuit extends between a tab protruding from each of the two end plates of the cell.

13. The battery module of claim 12, wherein the sensor circuit is riveted to each tab.

14. The battery module of any preceding claim, further comprising a non-conductive gasket with holes through which the cells contact one of the end plates.

15. The battery module of claim 14, wherein the non-conductive gasket is flexible.

16. The battery module of any preceding claim, wherein the cells are spaced apart and defines between them coolant passages .

17. The battery module of claim 16, wherein the end plates are provided with apertures for the passage of cooling fluid which align with at least some of the coolant passages defined by the cells.

18. The battery module of any preceding claim, wherein the terminals of the cells are exposed.

19. The battery module of any preceding claim, comprising two sleeve closures slidingly and sealingly engaging the ends of the sleeve.

20. The battery module of claim 19, wherein one sleeve closure has a coolant inlet through which cooling fluid may flow into the battery module, and the other sleeve closure has a coolant outlet through which cooling fluid may leave the sleeve .

21. A battery, comprising first and second terminal plates and a plurality of battery modules in accordance with any preceding claim, wherein each of the battery modules extend between the first and second terminal plates.

22. The battery of claim 21 comprising a plurality of ties between the terminal plates, the ties being tensioned to apply a compressive force to the battery modules.

23. The battery of claim 21 or 22, wherein each terminal plate comprises a plurality of interconnected connector plates, each of which is connected to one or more battery modules .

24. The battery of claim 23, further comprising a plurality of conductive connectors for electrical connecting two battery modules together, wherein the connector plates each include one or more apertures to collectively define how the

conductive connectors may be attached and thereby define how the battery modules of the battery may be electrically

connected .

25. A battery pack, comprising:

the battery of any one of claims 21 to 24; and

a coolant pump.

26. The battery pack of claim 25, further comprising a heat pump for cooling the coolant.

27. A hybrid vehicle comprising the battery of any one of claims 21 to 26.

28. A method of manufacturing a battery, comprising the steps of:

extruding a tube;

removing a desired length of the tube to form a sleeve for a battery module; and

sliding a stack of cell blocks into the sleeve.

29. The method of claim 28, further comprising the steps of: sandwiching the cell blocks between two sleeve closures to form a battery module; and

sandwiching one or more battery modules between first and second terminal plates.

30. The method of claim 28 or 29, further comprising the step of compressing the battery modules between the first and second terminal plates.

31. The method of any one of claims 28 to 30, further

comprising the step of manufacturing a plurality of cell blocks by connecting an end plate to a plurality of cells in parallel .

32. The method of claim 31, further comprising the steps of: manufacturing a cell stack by connecting a plurality of cell blocks in series; and

passing a rod through a hole in the end plates to align the plurality of cell blocks.

33. A method of manufacturing a battery to fit a pre-existing cavity, the method comprising:

identifying a cross-section and a length of the cavity; providing first and second terminal plates configured to fit within the cross-section of the cavity;

providing a sleeve having a length that fits within the length of the cavity;

forming a battery module by fitting a stack of cell blocks within the sleeve;

forming a battery by fitting the first and second

terminal plates to respective ends of the battery module;

installing the battery within the cavity.

34. A battery module comprising:

a sleeve closed at opposite ends by respective sleeve closures; and

a plurality of cells stacked in series within the sleeve, the plurality of cells connected to the sleeve closures,

wherein the sleeve closures slidably engage the ends of the sleeve.

35. The battery module of claim 34, wherein the sleeve closures sealingly engage the ends of the sleeve.

36. The battery module of claim 34 or 35, wherein one sleeve closure has an opening for connection through which cooling fluid may be provided, and the other sleeve closure has an opening through which cooling fluid may leave the sleeve.