Electrode Assembly for a Battery Cell and Battery Cell

Abstract

The invention concerns an electrode assembly (10) for a battery cell (2), comprising an anode (11) and a cathode (12) that are separated from one another by means of a separator (18), an electrically conductive layer (32) being arranged on the separator (18) and the electrically conductive layer (32) being covered at least partially with a protective film (34). The protective film (34) is a dense passivation layer or a polymer coating. The invention also concerns a battery cell (2), comprising at least one electrode assembly (10).

Claims

1. An electrode assembly for a battery cell, comprising: an anode and a cathode that are separated from one another by a separator; and an electrically conductive layer arranged on the separator, wherein the electrically conductive layer is covered at least partially with a protective film, and wherein the protective film is a dense passivation layer.

2. The electrode assembly according to claim 1, wherein the dense passivation layer is formed by anodic oxidation on a surface of the electrically conductive layer.

3. The electrode assembly according to claim 1, wherein the electrically conductive layer is made of aluminium and/or an aluminium compound.

4. The electrode assembly according to claim 1, wherein the electrically conductive layer is made of titanium and/or of a titanium compound.

5. An electrode assembly for a battery cell, comprising: an anode and a cathode that are separated from one another by means of a separator; and an electrically conductive layer arranged on the separator, wherein the electrically conductive layer is covered at least partially with a protective film, and wherein the protective film is a polymer coating.

6. The electrode assembly according to claim 5, wherein the polymer coating is formed by electrochemical polymerization onto a surface of the electrically conductive layer.

7. The electrode assembly according to claim 5, wherein the electrically conductive layer is made of copper.

8. The electrode assembly according to claim 5 the polymer coating is made of electrically nonconductive polymers made of alkanes.

9. The electrode assembly according to claim 5, wherein the polymer coating is made of aniline or thiophene.

10. The electrode assembly according to claim 1, wherein the electrically conductive layer is porous.

11. The electrode assembly according to claim 1, wherein the protective film is at least partially electrically insulating.

12. The electrode assembly according to claim 1, wherein the electrically conductive layer is arranged between the separator and the anode.

13. The electrode assembly according to claim 1, wherein the electrically conductive layer is arranged between the separator and the cathode.

14. The electrode assembly according to claim 1, wherein the protective film is arranged to a far side of the electrically conductive layer in respect to a side of the electrically conductive layer arranged on the separator.

15. A battery cell, comprising at least one electrode assembly according to claim 1.

16. Usage of a battery cell according to claim 15, in an electric vehicle (EV), in a hybrid electric vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or stationary.

17. The electrode assembly according to claim 5, wherein the electrically conductive layer is porous.

18. The electrode assembly according to claim 5, wherein the protective film is at least partially electrically insulating.

19. The electrode assembly according to claim 5, wherein the electrically conductive layer is arranged between the separator and one of the anode and the cathode.

20. The electrode assembly according to claim 5, wherein the protective film is arranged to a far side of the electrically conductive layer in respect to a side of the electrically conductive layer arranged on the separator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a better understanding of the aforementioned embodiments of the invention as well as additional embodiments thereof, reference should be made to the description of embodiments below, in conjunction with the appended drawings showing:

[0038] FIG. 1 a schematic view at a battery cell and

[0039] FIG. 2 a schematic view at a separator with an electrically conductive layer and a protective film of the battery cell shown in FIG. 1.

[0040] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The drawings only provide schematic views of the invention. Like reference numerals refer to corresponding parts, elements or components throughout the figures, unless indicated otherwise.

DESCRIPTION OF EMBODIMENTS

[0041] FIG. 1 shows a schematic view at a battery cell 2. The battery cell 2 contains a housing 3 which has, for example, a prismatic or a cylindrical shape. The battery cell 2 further contains an electrode assembly 10, which is arranged within the housing 3.

[0042] The electrode assembly 10 contains an anode 11, a cathode 12 and a separator 18 that is arranged between the anode 11 and the cathode 12. Furthermore, the battery cell 2 contains a negative terminal 15 and a positive terminal 16. The terminals 15, 16 serve for charging and discharging the battery cell 2 and are mounted on the housing 3.

[0043] Presently, the electrode assembly 10 is shaped as a jelly roll. That means the anode 11 and the cathode 12 of the electrode assembly 10 are flat foils that are wound about an axis. The separator 18 that is also a flat foil is wound between the anode 11 and the cathode 12 about the same axis.

[0044] The housing 3 of the battery cell 2 is filled with a liquid electrolyte such that the electrode assembly 10 is surrounded by the electrolyte. The separator 18, respectively parts of the separator 18, is soaked in said liquid electrolyte. The electrolyte is ion conductive. The separator 18 is also ion conductive and is electrically insulating.

[0045] The battery cell 2 can also be of pouch type, for example. That means the anode 11 and the cathode 12 of the electrode assembly 10 consist of several flat foils that are stacked alternately to form a pile or a stack. The separator 18 also consists of several flat foils that are stacked between the foils of the anode 11 and the foils of the cathode 12. A bag or a pouch made of an electrically insulating material surrounds the electrode assembly 10 such that the electrode assembly 10 is electrically insulated.

[0046] An electrically conductive layer 32 is arranged on the separator 18 of the electrode assembly 10. The electrically conductive layer 32 is thereby covered with a protective film 34. The electrically conductive layer 32 is in direct contact with the separator 18. The protective film 34 is applied to a far side of the electrically conductive layer 32 in respect to the separator 18. That means, the electrically conductive layer 32 is arranged between the separator 18 and the protective film 34.

[0047] Additionally to the protective film 34 on the electrically conductive layer 32, there might be a second insulating porous layer isolating the electrically conductive layer 32 against the anode 11.

[0048] The electrically conductive layer 32 arranged on the separator 18 is made of a metal, in particular of copper, aluminium or titanium. Thereat, the electrically conductive layer 32 is porous and is presently formed like a net which includes meshes, respectively pores. Said pores allow ions to pass through. Hence, the electrically conductive layer 32 is also ion conductive.

[0049] The protective film 34 arranged on the electrically conductive layer 32 is electrically insulating. But, the protective film 34 is covering continuously the electrically conductive layer 32 while still keeping the porosity of the electrically conductive layer 32 and the separator 18. Hence, the unit comprising the separator 18, the electrically conductive layer 32 and the protective film 34 is electrically insulating and ion conductive.

[0050] The anode 11 contains an anode active material 21 formed as a flat foil and an anode current collector 23 formed as a flat foil. The anode active material 21 and the anode current collector 23 are attached to one another. The anode current collector 23 is electrically conductive and is made of a metal, in particular of copper. The anode current collector 23 is electrically connected to the negative terminal 15 of the battery cell 2.

[0051] The cathode 12 contains a cathode active material 22 formed as a flat foil and a cathode current collector 24 formed as a flat foil. The cathode active material 22 and the cathode current collector 24 are attached to one another. The cathode current collector 24 is electrically conductive and is made of a metal, in particular of aluminium. The cathode current collector 24 is electrically connected to the positive terminal 16 of the battery cell 2.

[0052] The unit comprising the separator 18, the electrically conductive layer 32 and the protective film 34 is arranged within the electrode assembly 10 such that the separator 18 is in direct contact with the cathode active material 22. The protective film 34 on the electrically conductive layer 32 is in direct contact with the anode active material 21. Thus, the electrically conductive layer 32 is arranged between the separator 18 and the anode 11. Also the protective film 34 is arranged between the separator 18 and the anode 11.

[0053] FIG. 2 shows a schematic and detailed view at the unit comprising the separator 18, the electrically conductive layer 32 and the protective film 34 of the electrode assembly 10 of the battery cell 2 shown in FIG. 1. Thereat, a schematic sectional view of said unit is given.

[0054] As mentioned already, the electrically conductive layer 32 that is arranged on the separator 18 of the electrode assembly 10 is porous and is formed like a net which includes meshes, respectively pores. Said pores allow ions to pass through and hence, the pores render the electrically conductive layer 32 ion conductive.

[0055] The protective film 34 is covering the electrically conductive layer 32 such that the electrically conductive layer 32 cannot get in touch with the electrolyte within the battery cell 2. The electrically conductive layer 32 is enclosed between the protective film 34 and the separator 18.

[0056] According to a first exemplary embodiment which corresponds to the first aspect of the invention, the electrically conductive layer 32 is made of aluminium. The electrically conductive layer 32 is arranged on the separator 18 and the protective film 34 is arranged on the electrically conductive layer 32.

[0057] The protective film 34 is a passivation layer which is formed by anodic oxidation on a surface of the electrically conductive layer 32 which is located on the far side of the electrically conductive layer 32 in respect to the separator 18. Thereat, the protective film 34 is aluminium oxide (AL.sub.2O.sub.3), aluminium fluoride (AlF.sub.3) or mixed aluminium fluoride oxide (Al.sub.xF.sub.yO.sub.z) where x ranges from 1 to 2, y ranges from 0 to 3 and z ranges from 0 to 3. Said method of generating the protective film 34 as a passivation layer can also be transferred to other metals, in particular titanium. Advantageously, the protective film 34 is titanium oxide (TiO.sub.2), titanium fluoride (TiF.sub.4) or mixed titanium fluoride oxide (Ti.sub.xO.sub.yF.sub.z) where x ranges from 1 to 2, y ranges from 0 to 4 and z ranges from 0 to 4.

[0058] According to a second exemplary embodiment which corresponds to the second aspect of the invention, the electrically conductive layer 32 is made of copper. The electrically conductive layer 32 is arranged on the separator 18 and the protective film 34 is arranged on the electrically conductive layer 32.

[0059] The protective film 34 is a polymer coating which is made by electrochemical polymerisation onto a surface of the electrically conductive layer 32 which is located on the far side of the electrically conductive layer 32 in respect to the separator 18. Thereat, the protective film 34 is made of polypropylene. Alternatively, the protective film 34 can be made of aniline or of thiophene, for example.

[0060] The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings and those encompassed by the attached claims. The embodiments were chosen and described in order to explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.