High-strength battery electrode foil for the production of lithium-ion accumulators

1. A battery electrode foil comprising an aluminium alloy, wherein the aluminium alloy comprises the following composition in weight percent:

Si: 0.07-0.12% by weight,

Fe: 0.18-0.24% by weight,

Cu: 0.03-0.08% by weight,

Mn: 0.015-0.025% by weight,

Zn: ≤0.01% by weight, and

Ti: 0.015-0.025% by weight,

wherein the aluminium alloy can contain impurities of up to a maximum of 0.01% for each compound, in total up to a maximum of 0.03%,

wherein the remaining weight % of the aluminum alloy is aluminium, with the proviso that the aluminium content must be at least 99.5% by weight;

wherein the battery electrode foil has intermetallic phases of a diameter length of 0.1 to 1.0 μm with a density of ≤9500 particles/mm 2 , and

wherein the battery electrode foil has a thickness of 8 to 20 μm.

2. The battery electrode foil according to claim 1 , wherein the battery electrode foil has intermetallic phases of a diameter length of 0.1 to 1.0 μm with a density of ≤7000 particles/mm 2 .

3. The battery electrode foil according to claim 1 , wherein the battery electrode foil has a minimum electrical conductivity of 56% IACS.

4. The battery electrode foil according to claim 1 , wherein the battery electrode foil has a tensile strength (in the direction of rolling and transverse to the direction of rolling) Rm >250 MPa.

5. The battery electrode foil according to claim 1 , wherein said battery electrode foil has a surface roughness Ra of 0.07 to 0.22 μm on both sides.

6. The battery electrode foil according to claim 5 , wherein the difference in surface roughness Ra on both sides of the battery electrode foil is at most 0.03 μm.

7. The battery electrode foil according to claim 1 , wherein the battery electrode foil has a carbon coverage of <5 mg/m 2 .

8. The battery electrode foil according to claim 1 , wherein the surface tension of the battery electrode foil is >30 dyn/cm.

9. The battery electrode foil according to claim 8 , wherein the surface tension of the battery electrode foil is >32 dyn/cm.

10. The battery electrode foil according to claim 1 , wherein the battery electrode foil has a thickness of 12 μm.

11. The battery electrode foil according to claim 1 , wherein the battery electrode foil has the following mechanical properties:

Rm (in direction of rolling): ≥250 MPa,

Rm (transverse to rolling direction): ≥250 MPa,

Rp0.2 (in rolling direction): ≥200 MPa,

Rp0.2 (transverse to rolling direction): ≥200 MPa,

A100 (in rolling direction): ≥2.0%,

A100 (transverse to rolling direction) ≥2.0%.

12. The battery electrode foil according to claim 1 , characterised in that the Fe/Si ratio is in the range of 1.5 to 3.5.

13. The battery electrode foil according to claim 1 , characterised in that the Cu/Ti ratio is in the range of 2 to 5.

14. A method of manufacturing a battery electrode foil, comprising:

producing an aluminium hot-rolled strip with a hot-rolled thickness of at least 2.5 mm is provided from an aluminium alloy as described in claim 1 , and

cold rolling the aluminium hot strip in several cold rolling passes to a final thickness of 8 to 20 μm,

wherein cold rolling is carried out from an initial thickness of at least 1 mm without intermediate annealing.

15. The method according to claim 14 , wherein cold rolling from a hot strip thickness to the final thickness is carried out without intermediate annealing.

16. The method according to claim 14 , characterised in that the degree of rolling per cold rolling pass is at most 60% from an initial thickness of at least 0.55 mm.

17. The method according to claim 14 , characterised in that the aluminium strip, starting from a thickness of at least 0.1 mm, is cooled between two cold rolling passes.

18. The method according to claim 14 , characterised in that the aluminium strip is cold-rolled in a single layer to the final thickness.

19. A battery electrode foil produced by a method according to claim 14 .

20. A method of making an accumulator, the method comprising:

using the battery electrode foil according to claim 1 as a current collector foil, in the manufacture of an accumulator.

21. An accumulator comprising a current collector made of a battery electrode foil according to claim 1 .