A battery or battery cell having a heater

Abstract

A battery or battery cell according to the invention has a heater on it. The heater is a foil transfer technology manufactured metal foil. The metal foil is flexible, conductive, and solderable material. Further, the metal foil heater comprises pads for soldering.

Description

[0001] A battery or battery cell having a heater

[0002] Field of technology

[0003] The invention relates to a battery or battery cell having a heater on it.

[0004] Prior art

[0005] It is known to use printed heaters with the batteries and battery cells. The heaters can be used to increase the performance and lifetime of batteries. For example, elevated temperature of Li-anode batteries can be used to initiate the self-healing process (i.e. breaking the dendrites), and for solid state batteries higher ionic conductivity and thus better performance can be achieved by increasing the temperature to 60 °C for example. It is also well known that the voltage of the batteries will drop in cold conditions.

[0006] Integration of external heaters to batteries is complicated as well as time and space consuming. Printed heaters are thin and can be used as heaters. However, printing process set limitation to the battery manufacturing and formation of reliable electrical connection to ink derived conductors is difficult. Further, the resistance level of even the best printed heating structures is high which results increased voltage demand to achieve sufficient heating power. In addition, the printed heaters can have a substrate layer, which may create extra stiffness to the heater’s structure.

[0007] Short description

[0008] The object of the invention is to alleviate or even eliminate the problems said above. The object is achieved in a way described in the independent claims. Dependent claims illustrate different embodiments of the invention.

[0009] A battery or battery cell according to the invention has a heater on it. The heater is a foil transfer technology manufactured metal foil. The metal foil is flexible, conductive and solderable material. Further, the metal foil heater comprises pads for soldering. The pads are arranged not to raise temperature on the battery or the battery cell over a determinate temperature level during soldering.

[0010] List of figures

[0011] In the following, the invention is described in more detail by reference to the enclosed schematic drawings, where

[0012] Figure 1 illustrates an example of a heater, and

[0013] Figure 2 illustrates an example of a battery or battery cell according to the invention.

[0014] Description of the invention

[0015] Figure 1 illustrates an example of a metal foil heater manufactured by a foil transfer technology. A possible example of the foil transfer technology is disclosed in WO 2022 / 234189 publication. This publication is accompanied by reference to this description. A metal foil 1 is attached to a carrier layer 2 by an adhesive. A metal foil can be a thin undulating strip, which is heated by an electric current flowing through it. The metal foil heater 1 comprises pads 4 for soldering. Above the metal foil 1 there can be a protection layer 3 for protecting the metal foil during a storage period and transportation etc, i.e. before installation on the battery or the battery cell. The protection layer 3 is also attached to the metal foil 1 by an adhesive. Material of the protection layer is such a kind that it can be easily released from the metal foil (and the carrier layer 2).

[0016] When installing the metal foil 1 onto the battery or the battery cell, the protection layer 3 is taken away, and the metal foil is attached to the surface of the battery or the battery cell. The adhesive on the metal foil heater 1 is utilized for the attachment. After that the carrier layer 2 is taken away from the metal foil heater. The adhesives on both sides of the metal foil heater are selected so that these actions can be done. The adhesive above on the metal foil provides a good attachment to the surface of the battery or the battery cell. The adhesive on the other side of the metal foil (below on the metal foil) is not so strong than the adhesive above on the metal foil 1 . Therefore, the carrier layer 2 can be taken away without releasing the metal foil heater away from the surface of the battery I battery cell. Note that the terms “above” and “below” are used here in order to understand figure 1 better. It should be understood that the selection of the adhesives and material selection of the layers (the protection layer and the carrier layer) is made so, that the metal foil heater 1 can be properly attached onto the battery I battery cell and the carrier layer can be taken away without breaking the metal foil heater or releasing the metal foil heater from the battery I battery cell. It is noted that the metal foil is flexible, conductive and solderable material. Therefore, the the metal foil heater 1 can also be attached properly onto a three-dimensional surface (for example concave or convex surface) not just onto a plane surface.

[0017] A battery or a battery cell 5 according to the invention having a heater on it is shown in figure 2. As said, the heater 1 is a foil transfer technology manufactured metal foil. The metal foil is flexible, conductive and solderable material. Further, the metal foil heater comprises pads 4 for soldering. The area of the pads 4 can, for example, be 0,5 x 0,5 cm2. However, larger pads are more preferable, like 1 x 1 cm2, or even larger. The pads are arranged not to raise temperature on the battery or the battery cell 5 over a determinate temperature level during soldering. In this way the battery or the battery cell is not damaged when soldering wires 8A, 8B onto the pads 4. The soldering temperature is higher than melting temperatures of most materials used in the battery or battery cells. The battery cell 5 can be a pouch cell. The determinate temperature level is, for example, 80 °C .

[0018] The metal foil heater 1 comprises extensions 2A, 2B. Said pads 4 are at ends of the extensions. Having the extensions, the pads can be located away from the surface 5A of the battery or the batter cell 5. For example, the corners of the battery I battery cell can be utilized, or the extensions 2A, 3B may be turned away from the surface 5A.

[0019] It is also possible that the battery or battery cell 5 comprises an insulating piece 9 between each pad 4 and a surface 5A of the batter or the battery cell. The insulating piece is thermally insulating material, and it is attached to the surface 5A of the battery / a battery cell and the pads (and possibly to the extensions 2A, 2B) by a suitable adhesive / s. It can be also noted in the schematic example of figure 2 that the extensions 2A, 2B, can be utilized for locating the pads 4 outside of a designed heating area 6, which is heated by the metal foil heater 5.

[0020] So, the extensions 2A, 2B can be passages away from the surface 5A of the battery or the batter cell 5. It may even be possible that the carrier layer remains, at least partly, on the other side of the metal foil heater in order to support the extensions. It is also possible that said insulating piece is manufactured utilizing the foil transfer technology.

[0021] As said the metal foil 1 is thin. It’s thickness is 0,5 - 50 micrometres. The width of the metal foil conductor can, for example, be 0,5 - 10 mm, preferably 1 - 8 mm. The width range of 2 - 5 mm can be convenient in practice. The metal foil 1 is made of copper, brass, German silver, silver, gold, bronze, nickel, steel or aluminium. Metal is selected so that reliable electrical contacts can be created by soldering. As the heater element has a metallic conductivity, low voltages can be used for sufficient heating power. As said the metal foil heater has a flexible form factor and it can be attached on 3D shaped surfaces. It is noticeable that the metal foil heater can be attached to the battery cell before or at any stage of the cell manufacturing process or it can be retrofitted on to the existing battery or battery cell. So, the invention makes it possible to integrate the heater onto existing batteries or cells, and manufacturing lines do not need to be modified.

[0022] Figure 2 also discloses solders 7, which can be made on the pads 4 for electric wires 8A, 8B to supply power. So, the battery I battery cell can comprise solders 7 for external wires 8A, 8B. The solders 7 can be lead-free.

[0023] Utilizing the transfer foil technology, the heater can also be manufactured directly on the material used for a battery cell manufacturing. The specialty with this technology is that the heaters can be also attached to the battery or battery cell, and addition of any additional carriage material, which complicate the structure, can be avoided. Reliable electrical contacts can be created by soldering when materials suitable for soldering are used.

[0024] The metallic heater element can be used as a retrofitted heater element. Reliable electrical connection can be created. Low voltage operation is beneficial for the heater. The placement of the heater in the battery or battery cell allows the battery or battery cell to be heated below the above temperature in cold conditions or when stored at low temperatures.

[0025] In this invention, using a thin and flexible sheet of metal as a heater, a number of advantages are achieved. Firstly, thanks to the choice of metal, reliable electrical connections are easy to establish, and secondly, the flexible design of the heater allows it to be easily installed on batteries or battery cells of various sizes and shapes. In addition, the placement of the heater inside the battery or battery cell (made during manufacturing) makes it highly efficient in cold conditions, which improves its performance and extends its service life. Generally, the service life of the battery I battery cell is improved (breaking the dendrites). The invention is especially useful when the battery or battery cell is Lithium battery or battery cell.

[0026] It is evident from the above that the invention is not limited to the embodiments described in this text but can be implemented in many other different embodiments within the scope of the independent claims.

Claims

Claims1 . A battery or battery cell having a heater on it, characterised in that the heater (1 ) is a foil transfer technology manufactured metal foil, the metal foil being flexible, and being conductive and solderable material, the metal foil heater (1) comprising pads (4) for soldering, the pads being arranged not to raise temperature on the battery or the battery cell (5) over a determinate temperature level during soldering.

2. A battery or battery cell (5) according to claim 1 , characterised in that the metal foil heater (1) comprises extensions (2A, 2B), said pads (4) being at ends of the extensions.

3. A battery or battery cell (5) according to claim 1 or 2, characterised in that it comprises an insulating piece (9) between each pad and a surface (5A) of the battery or the battery cell.

4. A battery or battery cell (5) according to claim 1 , 2 or 3, characterised in that thickness of the metal foil (1) is 0,5 - 50 micrometres.

5. A battery or battery cell (5) according to claim 1 , 2, 3 or 4, characterised in that the metal foil (1) is made of copper, brass, German silver, silver, gold, bronze, nickel, steel or aluminium.

6. A battery or battery cell (5) according to claim 1 , 2, 3, 4 or 5, characterised in that it comprises solders (7) for external wires (8A, 8B).

7. A battery or battery cell according to claim 6, characterised in that the solders (7) are lead-free.

8. A battery cell 5 according to any of claim 1 - 7, characterised in that it is a pouch cell.

9. A battery cell 5 according to any of claim 1 - 8, characterised in that the heater (1) is retrofitted on to the battery or battery cell.

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