Influence of Electrolyte Conductivity on Energy Consumption and the Oxide Films Performance During Anodic Oxidation of Aluminum Electrolytic Capacitors.

Anode foil is a key component of aluminum electrolytic capacitors, and its performance largely depends on the anodic oxidation, or formation, process. During formation, electrical current converts the aluminum surface into a thin insulating oxide film that determines the capacitor's voltage resistance and reliability. Electrolyte conductivity controls how easily ions move through the solution: excessively low conductivity increases resistive energy losses, whereas excessively high conductivity can cause electrical discharges that damage the oxide film. This study investigated the effects of low (800 μS·cm-1), medium (1500 μS·cm-1), and high (2700 μS·cm-1) conductivities on energy consumption and oxide-film quality during formation at 520 V. The corresponding energy consumptions were 761.635, 707.381, and 754.238 kJ, respectively. Medium conductivity achieved the lowest energy consumption, representing reductions of 7.1% and 6.2% compared with low and high conductivities, respectively. However, the oxide film formed at medium conductivity showed lower crystallinity, revealing a trade-off between energy efficiency and film quality. Based on these results, a four-stage process was developed by applying high conductivity at ≤300 V, medium conductivity at 300-400 V, and low conductivity at 400-520 V. Compared with the conventional single-stage process, the optimized process reduced energy consumption by 8.4% and increased the voltage rise rate by approximately 6%. This voltage-dependent conductivity strategy provides a practical approach to producing high-quality anode foil with lower energy consumption.