Patent ID: 8871358

Claim:
A process for etching an anode foil, comprising: (a) applying a formation voltage to the foil of at least about 250 Volts; (b) treating the anode foil in an aqueous electrolyte bath composition comprising: an oxidizing agent comprising sodium perchlorate; a halide; and a sulfate in an amount ranging from about 200 parts per million (ppm) to about 2000 ppm, wherein the sulfate is selected from the group consisting of sodium sulfate, potassium sulfate, and lithium sulfate, and mixtures thereof, wherein the temperature of said electrolyte bath is about 60° C. to about 95° C.; and (c) passing a direct current (DC) charge through the anode foil while the foil is immersed in the electrolyte bath; such that the anode foil is etched, wherein the DC charge has a current density ranging from about 0.1 A/cm 2 to about 0.2 A/cm 2 .