ELECTRODE AND SECONDARY BATTERY CELL WITH SUCH AN ELECTRODE

Abstract

An electrode for a secondary battery cell has a foil-like electrode main body, the electrode main body including a collector section as a current collector and a contact section for electrically contacting a cell tab, the collector section and the contact section having different electrical conductivities and/or different thermal conductivities. A secondary battery cell has such an electrode, and an electrically powered motor vehicle may have a traction battery with such a secondary battery cell.

Claims

1. An electrode for a secondary battery cell, comprising: a foil-like electrode main body, wherein the electrode main body includes a collector section as a current collector and a contact section for electrically contacting a cell tab; and wherein the collector section and the contact section have different electrical conductivities and/or different thermal conductivities.

2. The electrode as recited in claim 1, wherein the collector section is coated with active material.

3. The electrode as recited in claim 1, wherein the collector section and the contact section of the electrode main body have different thicknesses.

4. The electrode as recited in claim 1, wherein the collector section is formed of a first material, and the contact section is formed of a second material different from the first material.

5. The electrode as recited in claim 1, wherein the collector section is formed of a polymer film or from a carbon foil, and the polymer film or the carbon foil are coated with a metal.

6. The electrode as recited in claim 1, wherein the collector section has a first portion and a second portion, and wherein the first portion and the second portion have different electrical and/or thermal conductivity.

7. The electrode as recited in claim 1, wherein the electrode main body has a plurality of contact sections.

8. The electrode as recited in claim 1, wherein the contact section extends along the entire width of the collector section.

9. A secondary battery cell, in particular a lithium-ion battery cell, having an electrode according to claim 1.

10. The secondary battery cell as recited in claim 9, wherein the secondary battery cell is a lithium-ion battery cell.

11. An electrically powered motor vehicle having a traction battery which has a secondary battery cell configured according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Exemplary embodiments of the invention are described in more detail below with reference to the drawings, in which:

[0030] FIG. 1 schematically shows an electrically powered motor vehicle whose traction battery (battery system) has a number of battery modules, the battery modules in turn including a number of secondary battery cells configured as lithium-ion battery cells;

[0031] FIG. 2a shows a schematic elevation view of a first variant of the electrode of one of the battery cells, the electrode having an electrode main body including a contact section and a collector section coated with active material;

[0032] FIG. 2b shows a schematic side view of the electrode of FIG. 2a, where the contact section has a greater thickness than the collector section;

[0033] FIG. 2c shows a schematic side view of the electrode in accordance with an alternative embodiment of the first variant, where the contact section has a smaller thickness than the collector section;

[0034] FIG. 3a shows a schematic side view of a second variant of the electrode, where the collector section thereof is formed using a polymer film or carbon foil provided with a metal layer;

[0035] FIG. 3b shows a schematic elevation view of an alternative embodiment of the second variant of the electrode, where the collector section has a first portion, which is formed using a metal foil, and a second portion, which is formed using a polymer film or carbon foil provided with a metal layer;

[0036] FIG. 3c shows the electrode of the alternative embodiment of the second variant in a schematic cross-sectional view taken in the plane IIIc indicated in FIG. 3b;

[0037] FIG. 4 shows a schematic elevation view of a third variant of the electrode, where the contact section extends along the entire width of the collector section; and

[0038] FIG. 5 shows a schematic elevation view of a fourth variant of the electrode, where the electrode is in strip form and has a plurality of contact sections at its longitudinal side.

[0039] Corresponding parts and quantities are given the same reference characters throughout the figures.

DETAILED DESCRIPTION OF THE INVENTION

[0040] FIG. 1 shows a motor vehicle 2 having a traction battery 4. Traction battery 4 has a number of battery modules 6, also referred to as cell modules. For improved clarity, only two of the battery modules 6 are shown.

[0041] Each of the battery modules 6 in turn includes a number of secondary battery cells 8 configured as lithium-ion battery cells, five of which are shown for each battery module 6. In FIG. 1, the battery cells 8 are configured, by way of example, as pouch cells, with the battery cells 8 being electrically interconnected by means of their cell tabs 10. In particular, the battery cells 8 of each battery module 6 are interconnected in series and/or in parallel via their cell tabs 10 in a manner not specifically shown. Moreover, battery modules 6 are interconnected in series and/or in parallel in a manner not specifically shown and are electrically connected to battery terminals 12 for a load.

[0042] A load is connected to battery terminals 12 of traction battery 4, the load here being in the form of an inverter 14 of a drive train of motor vehicle 2 and an electric motor 16 connected thereto. Inverter 14 converts the DC current and DC voltage provided by traction battery 4 to an AC current and AC voltage suitable for operation of electric motor 16. In summary, the traction battery provides electrical energy for driving motor vehicle 2.

[0043] In alternatives not specifically described herein, battery cells 8 are formed as round cells or as prismatic cells.

[0044] FIG. 2a shows a first variant of an electrode 18 of one of the battery cells 8. Electrode 18 includes a foil-like electrode main body 20, which is formed by a collector section 22 as a current collector and by a contact section 24. Contact section 24 serves for electrically contacting electrode 18 to cell tab 10 within battery cell 8, the cell tab 10 extending to the outside of the battery cell, where it is wired to a circuit.

[0045] In this first variant, electrode main body 20 is configured as a (single) metal foil. Consequently, contact section 24 and collector section 22 are formed monolithically; i.e. continuously with each other. Furthermore, electrode 18 includes active material, with which collector section 22 is coated on both sides. This coating of active material is denoted by reference numeral 26.

[0046] Electrode main body 20 defines a plane, with the main directions of extension being labeled B (for the width direction) and H (for the height direction) in the adjacent direction diagram. The direction perpendicular to this plane is denoted by reference numeral D (for the thickness direction). The specified directions apply analogously to the embodiments of FIGS. 2b through 4.

[0047] As can be seen in FIG. 2b, collector section 22 has a thickness d.sub.Kol and the contact section has a thickness d.sub.Kon, the thickness d.sub.Kon of contact section 24 being greater than the thickness d.sub.Kol of collector section 22. In other words, the spatial extent of contact section 24 in direction D is greater than the spatial extent of collector section 22 in this direction.

[0048] FIG. 2c illustrates an alternative embodiment of the electrode of the first variant. This alternative embodiment differs from the first variant only in that the thickness d.sub.Kol of collector section 22 is greater than the thickness d.sub.Kon of contact section 24.

[0049] In variants (not specifically described) of the electrodes 18 according to FIGS. 2a through 2c, collector section 22 is not provided with active material. In this case, the lithium deposits on the surface of collector section 22 during operation of the battery cell.

[0050] In summary, the contact section 24 and the collector section 22 according to the first variant and according to the alternative embodiment of the first variant have different thicknesses and, thus, different thermal and electrical conductivities.

[0051] FIG. 3a shows a second variant of electrode 18. In the second variant, collector section 22 and contact section 24 are joined together and, thus, are not formed monolithically with each other. Contact section 24 is disposed at the edge, here at an edge of collector section 22 extending in direction B. Contact section 24 preferably takes the form of a metal foil as a first material M1. The collector section is formed by a polymer film or carbon foil 28 as a second material M2. The polymer film or carbon foil 28 is provided with a metal layer 30. Metal layer 30 is electrically connected to contact section 24. In summary, the material M1 of contact section 24 is different from the material M2 of collector section 22.

[0052] According to an alternative not specifically illustrated, collector section 24 and contact section 24 are formed of films or foils of different materials, in particular using different metal foils, with collector section 24 and contact section 24 being joined together. In this connection, collector section 24 is, for example, coated with active material.

[0053] FIGS. 3b and 3c show an alternative embodiment of the second variant of electrode 18. Here, collector section 22 includes two portions 32 and 34. First portion 32 is formed using a metal foil and is electrically connected to contact section 24. The first portion 32 and the contact section are, for example, formed in one piece, in other words monolithically. The second portion 34 of collector section 22 is formed using a polymer film or carbon foil 28 which is coated on both sides with a metal layer 30. For example, first portion 32 surrounds second portion 34 like a frame. Alternatively, first portion 32 is in the form of a strip extending between second portion 34 and contact section 24 along the edge of collector section 22 facing the contact section 24.

[0054] Thus, in summary, first portion 32 and second portion 34 are different in terms of their electrical and/or thermal conductivity.

[0055] FIG. 4 shows a third variant of electrode 18. In this variant, contact portion 24 extends along the entire width of collector section 22; i.e., along the entire extent of collector section 22 in direction B. Analogously to the descriptions for FIGS. 2a through 2c, collector section 22 has a different thickness d.sub.Kol than contact section 24, and/or, analogously to the descriptions for FIGS. 3a through 3c, contact section 24 is formed of a different material than collector section 22.

[0056] FIG. 5 shows a further, fourth variant of electrode 18, which is in strip form. Thus, the electrode defines a plane, with the main directions of extension of electrode 18 forming the longitudinal direction L and the height direction H. Moreover, the extent of electrode 18 in longitudinal direction L is relatively large compared to the extent in height direction H. Such a strip-shaped electrode 18 is intended, for example, to form a jelly roll or a flat roll, which are typically used in round cells or in prismatic cells.

[0057] Electrode main body 20 includes the collector section 22 and a plurality of contact sections 24 which here by way of example are disposed on a common longitudinal side 36 of collector section 22, which longitudinal side 36 extends in longitudinal direction L. The contact sections are, for example, identical in design. However, it is also possible that the contact sections may have different thicknesses and/or different extents in the longitudinal direction, and/or may be formed of different materials. The collector section is formed, for example, from a metal foil provided with active material or from a polymer film or carbon foil with a metal layer.

[0058] Possibly, at least one of the contact sections 24 has a different thickness d.sub.Kon than collector section 22 and/or is formed of a different material than collector section 22.

[0059] In summary, in all of the variants and embodiments described above, the electrical conductivity σ.sub.Kol of collector section 22 and/or the thermal conductivity λ.sub.Kol of collector section 22 are/is different from the electrical conductivity σ.sub.Kol of contact section 24 and the thermal conductivity λ.sub.Kol of the contact section, respectively. In other words, the following holds: [0060] σ.sub.Kol≠.sub.Kon, and/or [0061] λ.sub.Kol≠λ.sub.Kon.

[0062] This advantageously allows the electrical conductivities and/or the thermal conductivities of collector section 22 and of contact section 24 to be independently adapted to the particular requirements on the battery cell and its electrodes, in particular to different requirements on collector section 22 and contact section 24 in terms of their thermal and/or electrical conductivities.

[0063] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention may also be derived therefrom by those skilled in the art without departing from the subject matter of the invention. Furthermore and in particular, all individual features described in connection with the exemplary embodiment may also be combined in other ways without departing from the subject matter of the invention.

LIST OF REFERENCE CHARACTERS

[0064] 2 electrically powered motor vehicle

[0065] 4 traction battery

[0066] 6 battery module

[0067] 8 lithium-ion battery cell

[0068] 10 cell tab

[0069] 12 battery terminal

[0070] 14 inverter

[0071] 16 electric motor

[0072] 18 electrode

[0073] 20 electrode main body

[0074] 22 collector section

[0075] 24 contact section

[0076] 26 coating of active material

[0077] 28 polymer film or carbon foil

[0078] 30 metal layer

[0079] 32 first portion of the collector section

[0080] 34 second portion of the collector section

[0081] 36 longitudinal side

[0082] B width direction

[0083] D thickness direction

[0084] H height direction

[0085] L longitudinal direction

[0086] d.sub.Kol thickness of the collector section

[0087] d.sub.Kon thickness of the contact section