Anodised aluminium is:

Al is not obtained electrolytically or at anode, because Al itself used as anode in anodizing process. There is no use of aluminum alloy in anodizing process because this process concern for the formation of aluminum oxide layer on the surface of Al, which acts as anode.

Anodizing aluminum is the process used for creating a layer of aluminum oxide on the surface of Al. In this process, dilute sulfuric acid is used as an electrolyte. This is an electrolysis process where Al acts as anode and any inert material acts as an a cathode. During the process, hydrogen is deposited at cathode whereas oxygen deposited at anode results in the formation of layer of aluminum oxide on the Al anode.