Fast Etching Preparation Technique for Al Electrode Foil in Al Electrolytic Capacitor

Aluminum electrode foil was prepared through fast etching method. The morphology and distribution of tunnel holes in the aluminum foil were observed by scanning electron microscopy (SEM). The effects of Cl^- content in etching solution for creating pits, shielding coefficient and total current on the specific capacitance of the aluminum foil were analyzed. The results showed that with the increase of the Cl^- content in etching solution for creating pits, shielding coefficient and total current, the specific capacitance of the aluminum electrode foil increased firstly and then decreased. Under the conditions of Cl^- concentration of 0.9 mol/L, shielding coefficient of 0.4 and total current of 1 400 A, the prepared aluminium foil had high proportion of single pores, large and uniform pore length, and reasonable pore distribution, so its specific capacitance reached the maximum value of 0.818 μF/cm².