Electrolytic cell drive current in opposite directions. The cell with the larger voltage is discharged, making it a galvanic cell, so P is the cathode and N is the anode as described above. But, the cell with the smaller voltage charges, making it an electrolytic cell. In the electrolytic cell, negative ions are driven towards P and positive ions towards N. Thus, the P electrode of the electrolytic cell meets the definition of anode while the electrolytic cell is being charged. Similarly, the N electrode of the electrolytic cell is the cathode while the electrolytic cell is being charged. As already noted,
SAL electrolytic capacitor 31, 2015 these are now end-of-life and have ceased production. Basic anode material of solid aluminum capacitors exists of highly purified aluminum with a purity of at least 99.99%. In an electrochemical process the anode material is etched (roughened) to increase the effective electrode surface. After that the roughened aluminum becomes oxidized or formed by an anodic oxidizing process. Thereby an electrical insulating oxide layer AlO is formed on the aluminum surface by applying an electric current in correct polarity in an electrolytic bath. This process of oxide formation is carried out into two reaction steps: The aluminum oxide layer