Effect of Bipolar Electrochemical Process on Tunnel Etching Characteristics of Aluminum Foil

In this study, closed bipolar electrochemical etching was introduced to prepare etched tunnels on aluminum foils. The morphological evolution and tunnel etching behaviors of aluminum foils in the traditional electrochemical etching system and closed bipolar electrochemical etching system were thoroughly investigated using scanning electron microscopy and electrochemical measurements. Compared with the tunnels etched on the aluminum foil by traditional electrochemical etching, those by closed bipolar electrochemical etching had a larger diameter and a more uniform distribution of length. These characteristics are beneficial for improving the specific surface area of the etched aluminum foil. Furthermore, aluminum foils do not need direct electricity connection, thus offering a potential advantage in industrial production.