WO2012125115A1

WO2012125115A1 - Battery module, vehicle, electric device and method

Info

Publication number: WO2012125115A1
Application number: PCT/SE2012/050289
Authority: WO
Inventors: Andreas LJUNGBERG; Jesper Martaeng; Fredrik Larsson
Original assignee: EFFPOWER AB
Current assignee: EFFPOWER AB
Priority date: 2011-03-15
Filing date: 2012-03-15
Publication date: 2012-09-20
Anticipated expiration: 2013-09-15

Abstract

Battery module (12) comprising a plurality of support structures (16) each having an I-shaped profile. Each support structure (16) accommodates at least one battery cell (14) in between the opposed ends (16a) of its I-shaped profile, and the battery module (12) is assembled by stacking said plurality of support structures (16) together.

Description

BATTERY MODULE, VEHICLE, ELECTRIC DEVICE AND METHOD

TECHNICAL FIELD

The present invention concerns a battery module comprising a plurality of battery cells, a vehicle or an electric device comprising at least one such a battery module, and a method for manufacturing such a battery module.

BACKGROUND OF THE INVENTION

A rechargeable battery or storage battery is known as a secondary battery because, (unlike a primary or disposable battery), its electrochemical reactions are electrically reversible. Rechargeable batteries come in many different shapes and sizes and several different combinations of chemicals are commonly used in such batteries, including: lead-acid, nickel cadmium (NiCd), nickel metal hydride (NiMH), lithium ion (Li-ion), and lithium ion polymer (Li-ion polymer). A plurality of battery cells may be connected together and used as the power source for motor drives, such as those in electric and hybrid electric vehicles. Each battery cell includes an electrode assembly in which a separator is interposed between a positive electrode and a negative electrode, a container to house the electrode assembly, a cap to seal the container, and a positive terminal and a negative terminal extending towards and protruding from the cap, and electrically connected to a collector of a positive electrode and a negative electrode of the electrode assembly. The battery cells of a secondary battery are spaced apart from each other and their terminals are connected to each other serially or in parallel to form a battery module. When a battery module is used for motor drives in applications requiring a high power source, such as in electric or hybrid electric vehicles, the terminals of the battery cells are serially connected.

Heat generated by each battery cell of a secondary battery must be efficiently transferred away from the battery cells so that minimal temperature differences arise within the battery since such temperature differences may lower charge-discharge efficiency, adversely affect the performance of the battery and damage the battery. US patent application no. US 2006/0216582 discloses a secondary battery module that includes a plurality of battery cells, a housing receiving the battery cells, a cell barrier plate disposed between the battery cells to transfer heat generated from the battery cells, a cooling plate disposed in contact with an end of the cell barrier plate, and a heat dissipation assembly disposed proximate to the cooling plate to dissipate heat transferred to the cooling plate. The cell barrier plate is either integrally formed with the cooling plate or fixed to the cooling plate by welding.

SUMMARY OF THE INVENTION

An object of the invention is to provide an improved battery module comprising a plurality of battery cells.

This object is achieved by a battery module comprising a plurality of support structures each having an I-shaped profile with opposed ends and a stem interconnecting the opposed sides, whereby each support structure accommodates at least one battery cell in between the opposed ends of its I-shaped profile. The battery module is assembled by stacking the plurality of support structures together, i.e. by stacking a plurality of battery cell-accommodating support structures together, or by stacking a plurality of support structures together and then accommodating a plurality of battery cells therein.

Such a battery module is mechanically robust and stable, cost effective, simple and non-labour intensive to manufacture, it is easy to dismount for repair, replacement or maintenance work, and a battery module of any required power and/or size may be assembled quickly and simply.

It should be noted that the expression "I-shaped profile" is not intended to mean that the stem of the I-shaped profile is necessarily longer than the two opposed ends of the I-shaped profile. The opposed ends and the stem of the I-shaped profile may be of the same length, or the opposed ends may be longer than the stem. The I-shaped profile need not necessarily be symmetrical and there need not necessarily be an angle of 90° between the stem of the I-shaped profile and the opposed ends of the I-shaped profile. Furthermore, the support structure may be of any uniform or non-uniform thickness. The expression "each support structure accommodates at least one battery cell between the opposed ends of its l-shaped profile" is intended to mean that substantially an entire battery cell of any shape and size, such as a pouch battery cell (also called a "coffee bag cell" or soft package cell), is arranged to fit between the opposed ends of the support structure's I-shaped profile. A pouch battery cell is a soft package battery cell that requires external mechanical support. Preferably, the at least one battery cell is placed in contact with the surface of the stem of the I-shaped profile for improved heat transfer. Ideally, the at least one battery cell has a surface contour that corresponds to the surface contour of the surface of the stem of the I-shaped profile. The at least one battery unit may for example have a flat surface that is placed against a flat surface of the stem of the I-shaped profile. It should also be noted that each support structure of the battery module according to the present invention does not necessarily have to accommodate at least one battery cell when the battery module is in use, but each support structure is arranged to enable it to accommodate at least one battery cell. For example one or more support structures may be arranged to accommodate cooling means, electronics or computer hardware or software within the battery module.

The expression "to stack" as used throughout this document is not intended to mean arranging in support structures in a vertical stack or pile, but means that a plurality of support structures may be arranged horizontally, vertically or in any other direction. A stack of support structures need not necessarily extend in a linear manner, but a stack of support structures may be arranged to extend in a non-linear manner to fit around a particular component in a vehicle or an electric device.

According to an embodiment of the invention each support structure comprises material having a thermal conductivity of 1 WnT¹ K^"1 , or higher at room temperature, 50 Wm^"1K^'1, 100 Wm^"1 K^"1, 200 Wm^"1K^"1 or higher, such as a metal or alloy with a high thermal conductivity, such as aluminium or copper or an alloy thereof, or a plastic or composite material with a high thermal conductivity or comprising a material with a high thermal conductivity, such as carbon fibre or metal. At least part of the support structure may be made from material having a thermal conductivity of 1 Wrn^'V^'1 or higher, or a support structure may be coated with material having a thermal conductivity of 1 Wrn^'V^'1 or higher. The support structure will thereby not only mechanically support, contain and protect the battery cells, but will also serve to efficiently transfer heat generated by the battery cells away from the battery cells.

According to another embodiment of the invention at least one of the two opposed ends of each support structure comprises connection means to connect the at least one opposed end to at least one opposed end of another support structure to allow the opposed ends of the plurality of support structures to form at least one cooling surface. The at least one cooling surface is preferably arranged to be a flat, smooth, and/or continuous cooling surface, which is advantageous for heat transfer since good thermal contact between the cooling surface and cooling means/media may be made. The at least one cooling surface may be provided with means, such as flanges or ribs, to increase the available surface area for heat transfer.

The connection means may be arranged to allow at least one opposed end of a support structure to slide into, and optionally to lock into, a corresponding connection means on at least one opposed end of another support structure. The support structures may be arranged to connect to one another by means of any male/female connection or a snap-fit or in any other suitable manner. According to a further embodiment of the invention two or more battery cells are accommodated in between the opposed ends of each I-shaped profile of each support structure. For example, one battery cell may be arranged on each side of the stem of the I-shaped profile. Depending on the width of the support structure, a plurality of battery cells may be placed on one or both sides of the stem of the I-shaped profile, whereby the width of the support structure would extend in a direction perpendicularly into this page if its I-shaped profile were viewed in the same way as the reader views an "I" printed on this page.

According to an embodiment of the invention the at least one battery cell is fixedly attached to the stem of the support structure, which stem extends between the two opposed ends of the I-shaped profile of the support structure. Such an attachment may be arranged to improve the thermal contact between the at least one battery cell and the support structure and/or to hold the battery cells in place while the battery module is being assembled. According to another embodiment of the invention the at least one battery cell is fixedly attached to the stem of the support structure by means of any suitable adhesive(s). The adhesive(s) may be thermally conducting and electrically isolating. It should be noted that the battery cells need not necessarily be fixedly attached to the support structure. They may merely be placed adjacent to the support structure while a battery module is being assembled.

According to a further embodiment of the invention the battery module comprises compressive material located adjacent to the at least one battery cell to allow the at least one battery cell to expand during use.

The present invention also concerns a vehicle, such as an electric or hybrid electric vehicle that is used to transport people and/or cargo, such as a bicycle, car, truck, motorcycle, train, ship, boat or aircraft, comprising at least one battery module according to any of the embodiments of the invention for any reason. The present invention further concerns a stationary or non-stationary electric device comprising at least one battery module according to any of the embodiments of the invention for any reason. The present invention further concerns a method for manufacturing a battery module comprising a plurality of battery cells. The method comprises the steps of:

a) manufacturing a plurality of support structures having an I-shaped profile with opposed ends and a stem interconnecting said opposed sides,

b) accommodating at least one battery cell in between the opposed ends of the I- shaped profile of each support structure, and

c) stacking a plurality of support structures together,

The order of steps b) and c) may be reversed, i.e. a plurality of battery cell- accommodating support structures may be stacked together, or a plurality of support structures may be stacked together and then a plurality of battery cells may be accommodated therein.

According to an embodiment of the invention step a) involves extruding a plurality of support structures having an I-shaped profile. According to another embodiment of the invention each support structure is manufactured from material having sufficient thermal conductivity for the application in which the battery module is to be used, for example a material having a thermal conductivity of 1 Wm^'1K^'1 or higher at room temperature.

According to a further embodiment of the invention step b) involves accommodating two or more battery cells in between the opposed ends of each I-shaped profile of each support structure. According to an embodiment of the invention step b) involves fixedly attaching the at least one battery cell to the stem of the support structure which stem extends between the two opposed ends of the I-shaped profile of the support structure.

According to another embodiment of the invention step b) involves fixedly attaching the at least one battery cell to the stem of the support structure by means of an adhesive. The adhesive may comprise a thermally conducting and electrically isolating adhesive.

According to a further embodiment of the invention the method comprises the step of providing at least one of the two opposed ends of each support structure with connection means to connect the at least one opposed end to at least one opposed end of another support structure to allow the opposed ends of the plurality of support structures to form at least one cooling surface when a plurality of support structures are stacked together. According to an embodiment of the invention the method comprises the step of providing compressive material adjacent to one or more battery cells. If any force is applied to the sides of a battery module according to the present invention during its manufacture, transportation, installation or operation, that force will be substantially equally distributed across all of its support structures and over the entire surface of the battery cells. Such compressive material will absorb the battery cells' expansion and apply a resilient opposing force on the surface of the battery cells during use. Such compressive material will even provide vibrational resistance and mechanical support for the battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be further explained by means of non-limiting examples with reference to the appended schematic figures where; Figure 1 shows a vehicle according to an embodiment of the invention,

Figure 2 shows a battery cell in perspective,

Figure 3 shows a battery cell-accommodating support structure according to an embodiment of the invention in perspective and seen from the side along line A-A in the figure on the left of figure 3,

Figure 4 shows a battery module according to an embodiment of the invention from the side,

Figure 5 shows a battery module according to an embodiment of the invention in perspective, and

Figure 6 is a flow diagram of a method according to an embodiment of the invention.

It should be noted that the drawings have not been drawn to scale and that the dimensions of certain features have been exaggerated for the sake of clarity.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 shows a vehicle 10 comprising a battery module 12 according to an embodiment of the present invention, which battery module 12 comprises a plurality of battery cells 14, such as a plurality of pouch battery cells 14, an example of which as shown in figure 2.

It should be noted that the tabs 14a containing the positive and negative terminal of a battery cell 14 do not necessarily have to be arranged on the same side of the battery cell 14 but they may be arranged on different sides. Furthermore, all of the tabs 14a of a plurality of battery cells 14 of a battery module 12 do not necessarily have to be located on the same side of a battery module 12 but may be located on two or more different sides of the battery module 12 in any repeating or non-repeating manner. For example the tabs 14a of one battery cell 12 may be located at a top side of the battery module 14 and the tabs 14a of an adjacent battery cell 12 may be located at the bottom side of the battery module 12. The embodiments of the present invention illustrated in figures 2-5 show a battery cells 14 having two tabs 14a located at the top side thereof and a battery module 12 in which all of the tabs 14a of the battery cells 14 are arranged at the top side thereof. This is however just one non-limiting example of a battery cell 14 and a battery module 12 according to the present invention.

The battery module 12 comprises a plurality of support structures 16 each having an I- shaped profile as shown in figure 3 of any suitable uniform or non-uniform thickness. Each l-shaped profile has opposed ends 16a and a stem 16b interconnecting the opposed ends 16a and comprises material having a thermal conductivity having sufficient thermal conductivity for the application in which the battery module 12 is to be used. Aluminium may for example be used to provide a lightweight mechanically robust support structure 16 having a high thermal conductivity. Alternatively or additionally, a support structure 16 may be arranged to be at least partly hollow in order to further decrease the weight of the battery module 12 according to the present invention.

The support structure 16 illustrated in figure 3 accommodates two battery cells 14 in between the opposed ends 16a of its I-shaped profile. The battery cells 14 may be adhered to the stem 16b of the I-shaped profile by means of a liquid or semi-liquid adhesive, an adhesive film or tape, such as double-sided adhesive tape. The adhesive may be a thermally conducting and electrically isolating adhesive 18. It should be noted that an adhesive need not necessarily cover the entire contact surface between a battery cell 14 and the support structure 16, it may namely be arranged to only partly the contact surface. Optionally, compressive material 20 may be placed adjacent to one or more battery cells 14 on the non-adhered adhered side thereof.

A battery module 12 may be assembled by stacking a plurality of such unit-battery accommodating support structures 16 together. Figure 3 shows a stack of six such unit-battery-accommodating support structures 16 from the side. It should be noted that a battery module may comprise any number of battery cells 14 depending on requirements. At least one of the two opposed ends 16a of each support structure 16 comprises connection means 22 (shown schematically in figure 2) to connect the at least one opposed end 16a to corresponding connection means 22 of at least one opposed end 16a of an adjacent support structure to allow the opposed ends 16a of the plurality of support structures 16 to form at least one cooling surface 24. The opposed ends 16a of the support structures 16 are arranged to be mechanically connected without the use of welding. In figure 4 flat, smooth and continuous cooling surfaces 24 are formed above and below the stack of unit-battery accommodating support structures 16, which is advantageous for heat transfer since good thermal contact between the cooling surface 24 and cooling means (not shown) may be made. Additionally, or alternatively the cooling surface may be provided with means, such as flanges or ribs, to increase the surface area available for heat transfer. Heat generated by the battery cells 14 during the use of the battery module 12 will be transferred though the thermally conducting support structures 16 to the cooling surfaces 24 which may be cooled in any manner known to the skilled person.

Figure 5 shows an assembled battery module 12 according to an embodiment of the invention. The opposed ends 16a of the support structures form cooling surfaces 24 and a robust housing for the battery module 12. If any force F is applied to the sides of the battery module 12 (as shown by the arrows in figure 5) or to its cooling surfaces 24 during its manufacture, transportation, installation or operation, that force will be substantially equally distributed across all of the support structures 16.

Figure 6 shows a method for manufacturing a battery module 12 comprising a plurality of battery cells 14 according to an embodiment of the invention. The method comprises the steps of manufacturing a plurality of support structures 16 having an I-shaped profile by extrusion from a suitable metal or plastic having a high thermal conductivity for example. At least one battery cell 14 is accommodated in between the opposed ends 16a of the I-shaped profile of each support structure 16 and fixedly attached to the stem 16b of the I-shaped profile, by means of an adhesive for example. A plurality of battery cell-accommodating support structures 16 is then stacked together. Optionally, compressive material 20 may be provided adjacent to one or more battery cells 14 before or after the support structures 16 have been stacked together. Further modifications of the invention within the scope of the claims will be apparent to a skilled person.

Claims

1. Battery module (12) comprising a plurality of battery cells (14), characterized in that said battery module (12) comprises a plurality of support structures (16) each having an I-shaped profile with opposed ends (16a) and a stem (16b) interconnecting said opposed sides (16a), whereby each support structure (16) accommodates at least one battery cell (14) in between said opposed ends (16a) of its I-shaped profile, and whereby said battery module (12) is assembled by stacking said plurality of support structures (16) together.

2. Battery module (12) according to claim 1 , characterized in that each said support structure (16) comprises material having a thermal conductivity of 1 Wm^'1K^'1 or higher at room temperature.

3. Battery module (12) according to claim 1 or 2, characterized in that at least one of the two opposed ends (16a) of each said support structure (16) comprises connection means (22) to connect said at least one opposed end to at least one opposed end of another support structure (16) to allow said opposed ends (16a) of said plurality of support structures (16) to form at least one cooling surface (24).

4. Battery module (12) according to any of the preceding claims, characterized in that two or more battery cells (14) are accommodated in between the opposed ends (16a) of each I-shaped profile of each said support structure (16).

5. Battery module (12) according to any of the preceding claims, characterized in that said at least one battery cell (14) is fixedly attached to said stem (16b) of said support structure (16).

6. Battery module (12) according to claim 5, characterized in that said at least one battery cell (14) is fixedly attached to said stem (16b) of said support structure (16) by means of an adhesive (18).

7. Battery module (12) according to claim 6, characterized in that said adhesive (18) is thermally conducting and electrically isolating.

8. Battery module (12) according to any of the preceding claims, characterized in that it comprises compressive material (20) located adjacent to said at least one battery cell (14).

9. Vehicle (10) or electric device, characterized in that it comprises at least one battery module (12) according to any of claim 1-8.

10. Method for manufacturing a battery module (12) comprising a plurality of battery cells (14), characterized in that it comprises the steps of: a) manufacturing a plurality of support structures (16) having an I-shaped profile with opposed ends (16a) and a stem (16b) interconnecting said opposed sides (16a),

b) accommodating at least one battery cell (14) in between the opposed ends (16a) of the I-shaped profile of each support structure (16), and

c) stacking a plurality of support structures (16) together.

1 1. Method according to claim 10, characterized in that step a) involves extruding said plurality of support structures (16) having an I-shaped profile.

12. Method according to claim 10 or 11 , characterized in that each support structure (16) is manufactured from material having a thermal conductivity of 1 Wrn^'V^'1 or higher at room temperature.

13. Method according to any of claims 10-12, characterized in that step b) involves accommodating two or more battery cells (14) in between the opposed ends (16a) of each I-shaped profile of each said support structure (16).

14. Method according to any of claims 10-13, characterized in that step b) involves fixedly attaching said at least one battery cell (14) to said stem (16b) of said support structure (16).

15. Method according to claim 14, characterized in that step b) involves fixedly attaching said at least one battery cell (14) to the stem (16b) of said support structure (16) by means of an adhesive (18).

16. Method according to claim 15, characterized in that said adhesive (18) comprises a thermally conducting and electrically isolating adhesive (18).

17. Method according to any of claims 10-16, characterized in that it comprises the step of providing at least one of the two opposed ends (16a) of each said support structure (16) with connection means (22) to connect said at least one opposed end to at least one opposed end of another support structure (16) to allow said opposed ends (16a) of said plurality of support structures (16) to form at least one cooling surface (24) when a plurality of support structures (16) are stacked together.

18. Method according to any of claims 10-17, characterized in that it comprises the step of providing compressive material (20) adjacent to said at least one battery cell