GB2458943A

GB2458943A - Improvements in or relating to battery systems

Info

Publication number: GB2458943A
Application number: GB0806088A
Authority: GB
Inventors: Simon Sheldon
Original assignee: AMBERJAC PROJECTS Ltd
Current assignee: AMBERJAC PROJECTS Ltd
Priority date: 2008-04-03
Filing date: 2008-04-03
Publication date: 2009-10-07
Anticipated expiration: 2028-04-03
Also published as: EP2277213A1; CN102047471A; GB0806088D0; WO2009121613A1; GB2458943B

Abstract

Connecting plates are provided for cells within a battery module comprising a plurality of cells and also to provide connection between modules in a multi-modular battery 5 system, the connection plates which comprise holes corresponding to individual cell terminals and are designed to enable improved ventilation of the battery system to minimise over heating and cell failure, increased resistance to short circuit hazards under critical cell failure and appropriate insulation can also be provided. The battery system and its use, particularly in battery powered vehicles is also provided.

Description

IMPROVEMENT IN OR RELATING TO BATIERY SYSTEMS

The present invention relates to improvements in or relating to batteries and is particularly concerned with battery packs for the provision of power to vehicles.

There is currently a growing need both from an environmental point of view and also an economic point of view to move away from fossil fuelled motorised vehicles. The internal combustion engine whether gasoline powered or diesel powered is the cause of significant environmental pollution due to undesirable gaseous emissions and the generation of particulate emissions. The increasing price of the fuels and the ultimate limitation on the availability of raw materials also require the development of alternate sources of power.

Battery powered vehicles are known, milk floats and golf carts have been battery powered for many years. However the battery systems required are extremely heavy and cumbersome and require a lot of space. The lifetime of the battery before a recharge is required is also limited. More recently hybrid vehicles such as the Prius by Toyota have appeared. These hybrid vehicles have the ability to work on either fossil fuel or electricity provided by batteries and they are able to switch from one source of power to the other. However, the battery life is limited and frequent recharging by the energy generated during the fossil fuel operation is required. A further disadvantage is that the battery system remain heavy and cumbersome and * requires a significant space within the vehicle structure to house the battery system.

*25 The present invention provides improved battery systems which overcome these e..

* * disadvantages.

-Within-this application the term "cell" refers to-an individual battery; the term "módule" refers to several cells mounted together to provide a power generation unit and the term "system" refers to several modules linked together as the overall power generation unit. In order to generate sufficient power for a sufficient period of time several modules may be assembled together. For example voltage can be built by connecting cells in series whereas capacity (the amount of energy storage) can be built by connecting cells in parallel. Nose to tail configuration means that modules are mounted so that the positive terminals of the cells (the nose) in one module is connected to the negative terminals of the cells (the tail) in an adjacent module.

I

By way of example if a battery system is to be assembled from cells of voltage 3.2 volts 10 cells may be connected in series to provide a module of 32 volts. If the cells also have a capacity of 1.6 Ah then connecting 10 cells in parallel will provide a capacity of 16 Ah. The energy storage is then the product of the voltage and the ampage. If again for example, an energy storage of about 45 kilo watt hours is required a system comprising 106 cells in parallel in each module and 84 modules in series in a nose to tail configurations may be employed. In this way if each cell is 3.2 volts and 1.6 Ah the system provides 106 x 1.6 Ah = 169.6 Ah and 84 x 3.2 volts = 268.8 volts. The capacity which is the product of the voltage and the ampage is 45588 watt hours or 45.588 kilo watt hours.

The present invention is concerned with improving the assembly and efficacity of such a battery system. Difficulties can arise in the assembly of such a system and in ensuring adequate electrical connection between the cells within a module and between modules within the system. Furthermore difficulties can arise within modules within the system which can lead to the development of excessive heat, perhaps causing fires and the release of corrosive materials.

The invention is applicable to any type of multicell system. The cells are S... . . ***. 20 conveniently mounted in a module in parallel with each other and they are conveniently cylindrical or prismatic or polymer and mounted so that the positive *S..

: terminal of each cell is at the same end in the module. Where several modules are employed they are preferably mounted in nose to tail configuration. It is then necessary to ensure that there is good electrical connection between the cells within *..: 25 the module to provide the required voltage and also good electrical connection between the modules to create the desired ampage and the combination of the two electrical connections ensures that the overall capacity is provided. It is also important to provide-adequate -insulation to prevent shorting of the cells and/or -modules.

The present invention therefore provides a battery system comprising at least two modules in which the cells in each module are mounted in parallel and the modules are mounted in a nose to tail configuration wherein electrical conductivity between the modules is provided by a connecting plate between the modules provided with holes positioned to correspond to the terminals of the cells within the modules.

S

In a further embodiment the present invention provides a system for the electrical connection of a plurality of cells to form a module comprising a plate provided with means for establishing electrical connection between the cells wherein the plate is provide with ventilation means whereby a fluid or gas may flow through the module around the cells.

In a preferred embodiment the plate comprises a series of holes positioned to correspond to the location of the positive and/or negative terminals of the cells and the connection is established by means of a metal strip that passes across the holes.

In a further preferment the strip does not cover the entire surface of the holes,in this way a gap can be provided at the edges of the strip to allow the flow of fluid along the axis of the module. In addition or alternatively the plate may be provided with additional holes to allow the ventilation. In the embodiment where a module is made up of several cylindrical cells lying adjacent to each other additional holes can be provided in the plate to coincide with the ends of the channels formed between adjacent cells.

In a further embodiment the fluid or gas is air and a fan is provided to drive the air *:::* along the axis of the module and, in a preferred embodiment, throughout the battery 20 system. In this way the battery system can be controlled and any emissions that may be created if a cells fails can be carried away. In this way a safer system is provided and the system will not fail due to the failure of a single cell.

The connector plate may be attached to both ends of a module and the plates may *25 be provided with means whereby adjacent plates may be secured to each other to *....S * * enable the production of the battery system. The modules may conveniently be bolted together as this allows the required mechanical and electrical assembly to be -achieved-in one process. in a-further preferenta conducting spacer is provided to -form a small gap between the modules to allow any pressure build up that may occur particularly due to cell failure to be vented. A gap of from 0.5 mm to 2.0 mm preferably from 1 mm to 1.5 mm is preferred. Conveniently the spacers may be made of steel or copper. For high power battery systems we prefer that the spacers have ventilation holes.

The nose to tail configuration has further benefits in that the risk of a short circuit on the edge of a module is reduced. Furthermore if a module fails it is easy to unbolt and replace. Additionally attachment means such as clips or brackets can readily be provided for securing the battery system in the desired location. Contact points may also be provided for linking two or more battery systems if the overall battery system comprises two or more battery systems mounted in different locations.

The use of the connector plates of the present invention has the additional benefit that the plate can act as a heat sink drawing thermal energy out of the cells and that energy may be dissipated into the surrounding atmosphere.

The plate employed in the connection system of the present invention should be of a conducting material to ensure good electrical contact between two modules when they are attached to each other. Copper is a particularly preferred metal from which to produce the plate due to its high electrical conductivity. Copper is not however a suitable material from which to form the strip that contacts the terminals of the cell because it is necessary to spot weld the strip to the top contact of the cell and copper cannot be welded. We have found that nickel or certain nickel alloys are suitable materials from which to produce the connector strip.

Accordingly in a further embodiment the present invention provides a connector plate * ** * for use in a battery module comprising a copper plate provided with a series of holes positioned to correspond to the positive and/or negative terminal contact points of the cells within the battery module provided with a connector strip bridging but not ** : covering the holes, said strip being weldable to the upper terminals of the cells to establish electrical contact with the cell and being dimensioned to provide a gap between the edge of the strip and the circumference of the hole. 25

The dissimilar nature of the material used to form the current carrying plate and the weldable connection to the top of the cells poses problems in joining said materials.

-Wehave found-that ultrasonic weldingis an effective method of joinihgtwo dissimilar -- materials without having to create a heat based fusion weld as is described in our co-filed application reference PAAJBA778. Ultrasonic welding creates an alloyed mix of the two materials where the weld is made. Also of importance is that no third party binding medium, such as solder, is needed. Furthermore, the ultrasonic method of creating this junction provides a join of low resistance and high quality.

In a further embodiment the invention provides a battery module having a connector plate as previously described attached thereto. In a yet further embodiment the invention provides a battery system comprising a plurality of modules connected together wherein electrical contact between cells within a module and between the modules is established by the connector plate optionally together with a spacer.

In a further embodiment appropriate electrical insulation is provided within the system to prevent shorting of the system. Insulation is particularly useful if the system comprises modules running alongside each other and it is also useful around the top of the cell to prevent short circuits between the two components of the battery system casing and the plate for joining the plurality of cells. The insulation can reduce the likelihood of shorts and contain the impact of module failure. Examples of suitable insulating materials that can be used are natural and synthetic rubbers and temperature resistant electrically insulating materials such as mica,alternatively a fomex film material may be used which may be held in place on the plate assembly by double sided tape Particularly preferred are synthetic rubbers such as polybutadiene, acrylonitrile butadiene copolymers and the like which can be formed into sheets and die cut so that they can be assembled with the modules and the connector plates to provide the required insulation within the battery system.

The invention is applicable tcf any type and size of cell and to modules containing any *. number of cells. It may be applied to nickel-cadmium, nickel metal hydride sometimes known as nickel hydrogen, lead-acid and lithium ion cells which may be cobalt, manganese or phosphate ions. The cells are generally cylindrical or prismatic *0 or polymer and the capacity of the individual cell can be selected according to the use to which the battery system is to be put.

: 25 In another embodiment the invention provides a battery system comprising a plurality * of modules connected together by connector plates as previously described and further provided with an insulation sheet as previously described. It is preferred that the insulation sheet is shaped to retain theventilatioA sytem ihén it is provided by the connector plate and hence it should not cover the gap between the cells or the gap provided between the edge of the connector strip and the circumference of the holes formed in the connector plate.

The present invention is applicable to battery systems designed to produce any power output. It is also applicable to systems based on different size and capacity cells and to modules containing different numbers of cells. The capacity of the cell, the number of cells within a module and the number of modules within the system may be selected according to the power output required. For example different power outputs are required to drive light vehicles such as golf carts, milk floats and light automobiles than are required to drive heavy automobiles and heavy goods vehicles. Furthermore, different power outputs may be required if the battery system is to be used as a power supply component in a hybrid vehicle in which the battery system can be charged when the vehicle is operating under another power source than if the battery system is to be the sole source of power. In addition the need for ventilation can depend upon the power output required; low power full electric vehicles such as golf carts, milk floats and light vehicles may not require ventilation.

Higher power hybrid vehicles or plug in hybrid vehicles where cooling (ventilation) holes and fluid flow are important.

The power requirements are given what are known as "C" ratings. If the battery has a capacity of 40 KWh and it is powering a motor capable of 40 KW the application rating for power draw is 1 C. If it were an 80 KWh battery for the same application the power draw would be C/2. If a 20 KWh battery was powering a motor capable of 40 KW the application rating would be 2C. Typically high power electric vehicles such as hybrid vehicles (HEV) have a rating of about 30C. Plug in hybrid vehicles (PHEV) have a rating of from 5C to 1 OC whereas electric vehicles (EV) typically have a rating * ** from 1C to 5C more typically from 1C to 2C. *.*. * .20 *.-.

In addition different system lifetimes between system recharges may be required *1S : according to the nature of the vehicle. A further consideration is that the weight of * the battery systems of the present invention should be selected to minimise the * **, impact on vehicle speed and any increase the fuel consumption when the battery system is used in a hybrid vehicle. The battery system of the present invention has ** . . . . * * the benefit of flexibility concerning the number, capacity and size of cells that can be employed in a module and the number of modules that can be employed.

Traditional battery systems for powering of vehicles are bulky and require the provision of a special locator within the vehicle. The modular system of the present invention has the added benefit that modules or batches of modules may be located at different positions within the vehicle and they may be connected by wiring to secure the desired output of the entire battery system. In this way space can be saved within the vehicle structure. For example modules or batches of modules may be mounted on various structural components of the vehicle such as frame rails and pillars, around a drive shaft and other similar positions. In a preferred embodiment the battery system is provided in a box preferably of glass fibre reinforced plastic to provide the necessary strength and insulation and can withstand the temperatures which may be generated by the operation of the battery system which can reach 160°C.

Whilst the invention has particular applicability to battery powered vehicles and has been described in relation to its use in battery powered vehicles it can be used in any environment where battery power is used. Examples of other environments where the invention may be used include stationary and stand by power, industrial battery applications, aviation batteries, batteries for space and exploration, submarine and ship borne battery systems, telecommunication and portable power applications.

The invention is illustrated but in no way limited by reference to the accompanying Figures in which Figure 1 shows a connector plate according to the present invention.

Figure 2 shows the connector plate of Figure 1 provided with the metal strip to establish electrical connection with the cells within a module. ° *e * S S * S.

Figure 3 shows a connector plate similar to Figure 1 but designed for use with a module containing a larger number of cells. S... *SS*

* Figure 4 shows the connector plate of Figure 2 attached to a battery module.

* 25 Figure 5 shows the connector plate of Figure 3 attached to a module.

a..... * ,

Figure 6 shows three of the battery modules shown in Figure 4 assembled in nose to tail configuration to provide a battery system. -Figure 7 shows three of the modules shown in Figure 3 assembled in nose to tail configuration to provide a battery system.

Figure 8 shows an insulating sheet which may be used in a battery system such as that show in Figure 6.

Figure 9 shows a battery system comprising several modules in a container.

Figure 1 shows a copper connector plate (1) provided with a series of holes (2) through which the positive terminal of a cell is exposed. The plate (1) is provided with an arm (3) which can be used for wire connections and the like. Figure 2 shows the reverse side of the connector plate (1) shown in Figure 1 provided with nickel containing metal connector strips (4), (5) and (6) which are attached to plate (1) and which will contact the positive terminal of a cell when the plate is mounted on a module.

Figure 3 shows a larger connector plate (7) similar to plate (1) of Figure 1 and provided with a series of holes (2).

Figure 4 shows how 24 cells (8) can be mounted as a module with a connector plate as shown in Figure 2 provided at the front end of the module connecting the positive terminals of the cells. A connector plate as shown in Figure 1 is provided at the back end of the module in readiness to provide a connection with a second module.

Figure 5 shows how connector plates as illustrated in Figure 3 can be used to create a 96 cell module. * SS

Figure 6 shows how three of the modules shown in Figure 4 can be connected in 20 series in nose to tail configuration to provide a 72 cell battery system. Similarly Figure 7 shows how 3 modules of the type shown in Figure 5 can be bolted together S...

: by bolts (9) to provide a battery system which can itself be provided with connecting * means (10) to attach the battery system at a required location. A small 1 mm gap is provided between the modules to allow venting in the event of pressure build up.

Figure 8 shows a mica insulating sheet (11) useful with the connector plates illustrated in Figures 1, 2, 4 and 6. The insulating sheet (11) being provided with a series of holes (12) which correspond to-the holes (2) in the connector plate of Figure 1.

Figure 9 shows a battery system comprising several of the modules shown in Figure 7 mounted in a container (13) for placement within, for example, a vehicle and provided with a socket (14) for the connection of a plug (not shown) to enable delivery of electricity from the system.

Claims

CLAIMS1. The present invention provides a battery system comprising at least two modules in which the cells in each module are mounted in parallel and the modules are mounted in a nose to tail configuration wherein electrical conductivity between the modules is provided by a connecting plate between the modules provided with holes positioned to correspond to the terminals of the cells within the modules.
2. A system for the electrical connection of a plurality of cells to form a module comprising a plate provided with means for establishing electrical connection between the cells wherein the plate is provide with ventilation means whereby a fluid or gas may flow through the module around the cells.
3. A system according to Claim I or Claim 2 wherein the plate comprises a series of holes positioned to correspond to the location of the positive terminals of the cells and the connection is established by means of a metal strip that passes across the holes. * S. * * .
4. A system according to Claim 3 in which the strip does not cover the entire surface of the holes. ****S S..
5. A system according to any of Claims 2 to 4 in which the fluid or gas is air.

*,25
6. A system according to any of the preceding claims in which a fan is provided * : * to drive a fluid along the axis of the module.
7. A system according to any of the preceding claims in which the plate is made of copper.
8. A system according to any of Claims 3 to 7 in which the connector strip is made of nickel or a nickel containing metal.
9. A connector plate for use in a battery module comprising a copper plate provided with a series of holes positioned to correspond to the positive and/or negative terminals of the cells within the module.
10. A battery module provided with one or more connector plates according to Claim 9.
11. A battery system comprising a plurality of modules according to Claim 10 connected together wherein electrical contact between cells within a module and between the modules is established by a connector plate according to one Claim 9.
12. A battery system according to Claim 11 wherein appropriate electrical insulation is provided within the system to prevent shorting of the system.
13. A battery system according to Claim 11 or Claim 12 in which the cells are selected from nickel-cadmium, lead-acid and lithium ion cells in which the ion is selected from cobalt, manganese or phosphate.
14. A battery system according to any of Claims 11 to 13 wherein conducting spacers are provided between the modules.
15. A battery system according to Claim 14 in which the spacers are of copper or steel. * S..r
16. A battery system according to any of the preceding claims in which means are provided as adjuncts to the connector plate for attaching the battery system. S... * 25 S...
17. The use of battery system according to any of Claims 11 to 16 for providing power to automotive vehicles.
18. The use according to Claim 17 in which the vehicle is an EV and the battery system has a rating of IC to 5C.
19. The use according to Claim 17 in which the vehicle is a PHEV and the battery system has a rating of 5C to 1 OC.
20. The use according to Claim 17 in which the vehicle is an HEV and the battery system has a rating of about 30C.
21. The use according to any of Claims 17 to 20 in which the automotive vehicle is an automobile, a bus or a truck.
22. An automotive vehicle powered by a battery system according to any one of Claims 11 to 16
23. A vehicle according to Claim 22 selected from an EV, a PHEV and an HEy.
24. An automotive vehicle according to Claim 22 or Claim 23 comprising an automobile, a bus or a truck. * ** * * * * ** **** * * **** S... *.*SS S...S *SSS 5.... S *