DE102019105120A1 - Current arrester for a battery cell of a motor vehicle - Google Patents

Abstract

The present invention relates to a current arrester (1) for a battery cell, the current arrester (1) having a core area (2) and a shell area (3), the core area (2) having a first material and the shell area (3) a second Having material, and wherein the shell region (3) at least partially encloses the core region (2).

Description

The present invention relates to a current collector for a battery cell of a motor vehicle according to claim 1. Furthermore, the invention relates to a battery cell with the aforementioned current collector according to claim 9. Furthermore, the present invention relates to a motor vehicle equipped with this battery cell according to claim 11.

Electrodes for battery cells typically include anodes and cathodes with massive current collectors, which are constructed either from copper or from aluminum and have an active material coating. For example, an anode with a solid copper current collector and an active material coating on both sides is provided, and a cathode with a solid aluminum current collector and an active material coating on both sides

Electrodes for battery cells typically include anodes and cathodes with massive current collectors, which are constructed either from copper or from aluminum and have an active material coating. For example, an anode with a solid copper current collector and active material coating on both sides is provided and a cathode with a solid aluminum current collector and active material coating on both sides

Both electrode current collectors - cathode and anode - comprise copper, typically 5 to 30 µm in solid construction, or aluminum, typically 5 to 30 µm in solid construction. The electrode tracks are rolled up into a cell roll, separated by separators.

For example, the anode is formed with a solid copper current conductor and an active material coating on both sides and the cathode with a solid aluminum current conductor and an active material coating on both sides. The battery cell can be designed as an electrode stack or as an electrode coil.

In the side area without active material coating, the individual electrode windings of the cell coil are welded together for the anode and the cathode, typically by ultrasonic welding, spot welding or laser welding.

In the event of a fault in the lithium-ion cell, for example due to overheating, internal short-circuit or overcharging, the cell materials can react exothermically with one another and, in the worst case, lead to a cell fire.

During this thermal runaway of the battery cell ("thermal runaway"), the aluminum current arresters in particular also influence the amount of energy released during the thermal runaway. The aluminum reacts as a reducing agent with the metal oxides from the cathode, releasing a lot of heat and is oxidized in the process, or the metal oxides contained in the cathode are reduced. The high surface area of the entire aluminum current arrester in direct contact with the cathode active material metal oxides additionally intensifies the reaction.

It is therefore an object of the present invention to provide a current conductor for a battery cell which has a low aluminum content.

This object is achieved by a current arrester, a battery cell and a motor vehicle according to Claims 1, 9 and 11. Advantageous embodiments and developments can be found in the subclaims, the following description and the figures.

The current conductor for a battery cell according to a first aspect of the present invention comprises a core area and a shell area, wherein the core area comprises a first material and the shell area comprises a second material, and wherein the shell area at least partially encloses the core area. The shell area can also completely enclose the core area.

In other words, the current arrester is designed as a "core-shell", English for "core-shell" current arrester, i.e. the current arrester has a two-component structure, the two components being core and shell. This hybrid core-shell construction enables the use of different materials with adapted and coordinated material properties.

The “core-shell” construction of the electrode current arrester can significantly reduce the amount of aluminum in the current arrester. A conventional aluminum current conductor typically has a thickness of approximately 10 to 25 µm.

In the “core-shell” structure of the electrode current conductor of the present invention, the aluminum layer processed thereon can be significantly thinner, for example with a thickness of 10 nm to 1 μm; such a thin layer coating is already sufficient to prevent exposure of the copper to the outside . Therefore, through the concept of the present invention, the amount of aluminum installed in the battery cell can be reduced by a factor 25th to 1000 to be humiliated.

The amount of aluminum present in the battery cell for a possible, unwanted thermite reaction is thus significantly reduced and thus also the amount of energy released during the “thermal runaway” of the battery cell. The battery cell and also the overall system of module and battery pack containing the battery cell (s) are safer to handle and operate, i.e. there is a reduced fire load due to the reduced aluminum content and there is a reduced probability that the battery cell will become an unwanted ignition source as the absolute probability of starting a thermite reaction is significantly reduced.

Because electrode current collectors can be made much thinner from copper than from aluminum, the use of this core-shell current collector can potentially achieve higher energy densities for the battery cell. Copper current collectors typically have a thickness in a range from 6 µm to 12 µm, aluminum current collectors a thickness in a range from 10 µm to 25 µm due to the poor electrical conductivity.

Even after coating with aluminum, for example, Cu-Al core-shell are current conductors for the cathode by around a factor 2 thinner than conventional current arresters made of solid aluminum.

As a result, the volumetric energy density of the cell can be increased while at the same time increasing safety. Due to the higher specific electrical conductivity of copper compared to aluminum, the absolute conductivity of the cathode current arrester can be maintained despite its lower thickness.

Due to the almost twice as high thermal conductivity of copper, approx. 398 W / mK, compared to aluminum, approx. 234 W / mK, depending on the thickness ratio of the conventional current arrester to the core-shell (Cu / Al) current arrester, an at least just as powerful if it is not even possible to achieve an improved cooling of the electrode stack during operation of the battery cell. This is advantageous for good aging behavior of the battery cell, particularly under extreme conditions, such as rapid charging of the battery cell.

Due to the significantly higher tensile and tear strength of copper compared to aluminum, a significantly better processability can potentially be achieved even with a thinner core-shell (Cu / Al) current collector foil, for example when coating and calendering the electrodes.

In an advantageous embodiment of the present invention it is provided that the first material is copper or a copper alloy.

In an advantageous embodiment of the present invention it is provided that the second material is aluminum or an aluminum alloy.

In an advantageous embodiment of the present invention it is provided that the second material is an electrical conductor.

In an advantageous embodiment of the present invention it is provided that the shell area is designed to be enclosed by an electrode active material.

In an advantageous embodiment of the present invention it is provided that the core area is designed to provide electrical conductivity of the current conductor.

In an advantageous embodiment of the present invention it is provided that the core area is designed to provide thermal conductivity of the current conductor.

In an advantageous embodiment of the present invention it is provided that the shell area is designed to protect the core area from corrosion and / or to avoid exposure of the core area.

In an advantageous embodiment of the present invention it is provided that the core area is designed as an electrode film and has a thickness of 4 μm to 16 μm, preferably 6 μm to 12 μm, particularly preferably 8 μm to 10 μm, and the shell area as a coating of the electrode film is formed and has a thickness of up to 1 μm, preferably of up to 100 nm, particularly preferably of up to 10 nm.

In an advantageous embodiment of the present invention it is provided that the current arrester is designed as a cathode current arrester for a cathode of the battery cell.

In an advantageous embodiment of the present invention it is provided that the shell area encloses the core area in such a way that a shielding effect against materials of the battery cell is achieved for the core area.

According to a further, second aspect of the present invention, a battery cell is provided, comprising the current conductor according to the first aspect or an embodiment of the first Aspect, wherein the battery cell further comprises an electrode active material, wherein the shell region of the current conductor is designed to be enclosed by the electrode active material.

In an advantageous embodiment of the present invention it is provided that the battery cell also has an active electrode material, the shell area of the current conductor being designed to be enclosed by the active electrode material.

According to a further, third aspect of the present invention, a motor vehicle is provided, the motor vehicle comprising a battery cell according to the second aspect or an embodiment of the second aspect and comprising the current conductor according to the first aspect or an embodiment of the first aspect.

The features of the present invention described above can be combined with one another as far as possible, even if it is not explicitly described above.

Further features, advantages and possible applications of the present invention emerge from the following description of the exemplary embodiments and the figures. All of the features described and / or shown in the figures, individually and in any combination, form the subject matter of the invention, regardless of their composition in the individual claims or their references. In the figures, the same reference symbols stand for the same or similar objects.

• 1 zeigt eine schematische Darstellung von herkömmlichen Stromableitern mit beidseitiger Elektrodenbeschichtung zur Erläuterung der Erfindung;
• 2 zeigt eine schematische Darstellung eines Elektrodenstapels bzw. -wickels einer herkömmlichen Batteriezelle zur Erläuterung der Erfindung.
• 3 zeigt eine schematische Darstellung eines Stromableiters für eine Batteriezelle gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;
• 4 zeigt eine schematische Darstellung einer Batteriezelle gemäß einem Ausführungsbeispiel der vorliegenden Erfindung.

The following is a brief description of figures of the present invention.

• 1 shows a schematic representation of conventional current conductors with double-sided electrode coating to explain the invention;
• 2 shows a schematic representation of an electrode stack or coil of a conventional battery cell to explain the invention.
• 3 shows a schematic representation of a current conductor for a battery cell according to an embodiment of the present invention;
• 4th shows a schematic representation of a battery cell according to an embodiment of the present invention.

Referring to FIG 1 to 4th a detailed description of embodiments of the present invention.

The 1 shows a schematic representation of conventional current conductors with double-sided electrode coating to explain the invention.

In 1 you can see not only the current arrester, but two current arresters - cathode-side current arrester 1a or anode-side current arrester 1b with double-sided electrode coating 4a and 4b . The coating 4th is not the same for anode and cathode, ie a cathode-side coating is used 4a and anode-side coating 4b used.

The 2 shows a schematic representation of an electrode stack or coil of a conventional battery cell to explain the invention. The other components of a battery cell, such as electrolyte, other mechanical components of the current arrester, cell housing with associated cell terminals are in the 2 not shown.

The 3 schematically shows the cross section of a current conductor with active material coating for a battery cell according to an embodiment of the present invention.

For correct functioning of the battery cell, it is essential in the case of the design of the current conductor as a cathode current conductor, as in the exemplary embodiment as in FIG 3 shown, it is essential that the metallic current conductor core - for example copper - is completely or completely enclosed by the shell material of the current conductor - for example aluminum.

For a better understanding of the present invention, only schematic cross-sections are shown in the figures. For example, the core structures or the current arrester are largely or even completely covered with, for example, aluminum. The core is thus enclosed everywhere and not just inside or outside the active material coating.

The Indian 3 The current conductor shown for a battery cell is designed in a core-shell design, with the core area 2 a copper current collector foil is provided, which is formed, for example, in a thickness range of 4 to 15 μm.

According to a further exemplary embodiment of the present invention, the current collector foil can be formed from metal, including from non-copper metals, which are largely stable in the environmental parameters of a thermal runaway.

By vapor deposition, electrochemical deposition, sputtering, cathode atomization, lamination, hot pressing or hot rolling, a coating can be used as a shell layer or shell area 3 are applied, for example an outer layer with a layer thickness of, for example, 10 nm to 1 μm.

The surrounding aluminum layer can be used as a shell area 3 the core area 2 at least partially or completely enclose. The core should be completely enclosed - or at least in relevant areas - so that it does not oxidize at corresponding cathode potentials and dissolve in the course of the oxidation.

Alternatively, instead of aluminum, can be used as the shell area 3 any other conductive material can also be applied that is stable under the operating conditions in the battery cell at the prevailing cathode potential or the core area 2 passivated, for example titanium or a titanium alloy for the shell area 3 be used.

Furthermore, the enveloping aluminum layer or the shell area 3 be further processed by coating with an electrode active material or a cathode active material.

The 4th shows a schematic representation of a battery cell according to an embodiment of the present invention.

The 4th shows a cathode-side current collector 1a and a current collector on the anode side 1b .

The coating 4th is for anode and cathode in the present, in the 4th The illustrated embodiment is the same, but a cathode-side coating can also be used 4a and anode-side coating 4b be used.

In addition, it should be noted that “comprehensive” does not exclude any other elements or steps and “one” or “one” does not exclude a large number. It should also be noted that features or steps that have been described with reference to one of the above exemplary embodiments can also be used in combination with other features or steps of other exemplary embodiments described above. Reference signs in the claims are not to be regarded as a restriction.

List of reference symbols

1

Current arrester

2

Core area

3

Shell area

4th

Electrode active material

6th

separator

10

Battery cell

20th

Motor vehicle

Claims (11)

Current arrester (1) for a battery cell, wherein the current conductor (1) has a core area (2) and a shell area (3), wherein the core region (2) comprises a first material and the shell region (3) comprises a second material, and wherein the shell area (3) at least partially encloses the core area (2). Current arrester (1) Claim 1 wherein the first material is copper or a copper alloy; and / or wherein the second material is aluminum or an aluminum alloy; and / or wherein the second material is an electrical conductor. Current arrester (1) Claim 1 or 2 , wherein the shell area (3) is designed to be enclosed by an electrode active material. Current conductor (1) according to one of the preceding claims, wherein the core region (2) is designed to provide electrical conductivity of the current conductor. Current conductor (1) according to one of the preceding claims, wherein the shell area (3) is designed to protect the core area (2) from corrosion and / or to avoid exposure of the core area (2). Current conductor (1) according to one of the preceding claims, wherein the core area (2) is designed as an electrode film and has a thickness of 4 µm to 16 µm, preferably 6 µm to 12 µm, particularly preferably 8 µm to 10 µm and wherein the shell region (3) is designed as a coating of the electrode film and has a thickness of up to 1 μm, preferably of up to 100 nm, particularly preferably of up to 10 nm. Current collector (1) according to one of the preceding claims, wherein the current collector (1) as a Cathode current arrester is designed for a cathode of the battery cell. Current conductor (1) according to one of the preceding claims, wherein the shell area (3) encloses the core area (2) in such a way that a shielding effect against materials of the battery cell is achieved for the core area. Battery cell (10) comprising a current conductor (1) according to one of the preceding claims, wherein the battery cell (10) further comprises an electrode active material, the shell region (3) of the current conductor (1) being designed to be enclosed by the electrode active material. Battery cell (10) comprising a current collector (1) according to one of the Claims 1 to 8th , wherein the first material is copper or a copper alloy and wherein the second material is aluminum or an aluminum alloy and wherein a thickness ratio between the shell region (3) and the core region (2) is provided so that a limit value for a Aluminum content of the battery cell is not exceeded. Motor vehicle (20) comprising a battery cell (10) according to Claim 9 or 10 .

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