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.