Method for producing electrode foils for capacitors, electrode foils, and capacitors comprising said electrode foils

1. A method for producing electrode foils for an electrolytic capacitor, comprising the method steps of:

A) providing a metal foil for the electrolytic capacitor,

B) transferring microstructures located on a stamping die to a main surface of the metal foil by a reforming process as part of producing the electrolytic capacitor, the microstructures comprising trenches with an aspect ratio of at least 4:1 being produced, the trenches having a depth of at least 20 μm and a width of 5 μm.

2. The method according to claim 1 , the metal foil comprising a valve metal being used in method step A).

3. The method according to claim 1 , with a method step C) following the method step B)

C) producing a metal oxide layer on the metal foil.

4. The method according to claim 1 , in method step B) the metal foil being positioned between the stamping die and an additional stamping die and the microstructures located on the two stamping dies being transferred onto the main surfaces of the metal foil by pressing.

5. The method according to claim 1 , designed as a continuous process, in method step B) the metal foil being passed between one rotating roll as the stamping die and an additional rotating roll as an additional stamping die and the microstructures thereby transferred onto at least the main surface of the metal foil.

6. The method according to claim 1 , in method step B) regular microstructures being produced.

7. The method according to claim 1 , in method step B) the stamping die and an additional stamping due being pressed against the metal foil at a temperature of below 400° C.

8. The method according to claim 1 , in method step B) the stamping die, and the metal foil and an additional stamping die being pressed against one another with a pressure of 10 to 100 MPa.

9. The method according to claim 1 , in method step A) the metal foil with a crystalline texture, for example a cubic texture, of <90% being provided.

10. The method according to claim 1 , in method step A) a metal foil with a purity of >95% being provided.

11. The method according to claim 1 , in method step A) a metal foil with a thickness of at least 80 μm being provided.

12. The method according to claim 1 , in method step B) the microstructures being transferred to the main surface of the metal foil as a multiplicity of depressions.

13. An electrode foil for an electrolytic capacitor, comprising:

a metal foil with regular microstructures on at least one main surface, the regular microstructures comprising trenches with an aspect ratio of at least 4:1, the trenches having a depth of at least 20 μm and a width of 5 μm, the metal foil being used in the electrolytic capacitor.

14. The electrode foil for capacitors according to claim 13 , the metal foil comprising a valve metal.

15. The electrode foil according to claim 13 , the metal foil comprising a crystalline (cubic) texture of <90%.

16. The electrode foil according to claim 13 , a metal oxide layer being arranged over the microstructures.

17. The electrode foil according to claim 13 , the microstructures taking the form of a multiplicity of depressions.

18. An electrolytic capacitor, comprising:

an electrode foil according to claim 13 as a first electrode,

a further metal foil as a current collector for a second electrode and

an electrolyte solution, which is arranged between the first electrode and the current collector of the second electrode.