Effect of hydration on microstructure and property of anodized oxide film for aluminum electrolytic capacitor

Controlling Dielectric Film Defects to Increase the Breakdown Voltage of Conductive Polymer Solid Capacitors

“…In aluminum solid polymer capacitors, at low anodizing voltages (up to 100 V), the breakdown voltage is close or equal to the anodizing voltage; nevertheless, at high anodizing voltages (up to 1000 V), the gap between the breakdown voltage and the anodizing voltage is remarkableas was evidenced in this researchand the reason for the low breakdown potential is unclear in the literature. Our research reports a breakdown voltage higher than the anodizing potential by performing a posthydration treatment of the dielectric layer, a phenomenon that is not observed even in aluminum electrolytic capacitors. ,, On the other hand, in high-voltage aluminum electrolytic capacitors, etched aluminum foils with many tunnel pits have been used to reach a high capacitance due to the high surface area. ,, For increasing the breakdown voltage, a thicker dielectric layer is usually developed by applying higher anodizing voltages (∼1000 V), dramatically reducing the capacitance value due to the high dielectric layer thickness and the sealing of the tunnel pits. Consequently, the posthydration treatment is a promising and simple treatment to enhance the breakdown voltage of solid conductive polymer capacitors and avoid a dramatic reduction in capacitance.…”

“…The surface images were observed before the PEDOT:PSS coating, and the cross sections were imaged after the coating. The hot water reaction offers the ability to grow metal oxide nanostructures 28,44 due to forming a lamellae structure oriented approximately perpendicular to the substrate surface, which consists of pseudoboehmite, as it is well-known in the literature. 45,46 The pseudoboehmite structure obtained remains after anodizing and the second boiling water treatment, and no differences are observed from the surface observations (Figure 1a and 1d).…”

“…Our research reports a breakdown voltage higher than the anodizing potential by performing a posthydration treatment of the dielectric layer, a phenomenon that is not observed even in aluminum electrolytic capacitors. 44,58,59 On the other hand, in high-voltage aluminum electrolytic capacitors, etched aluminum foils with many tunnel pits have been used to reach a high capacitance due to the high surface area. 37,60,61 For increasing the breakdown voltage, a thicker dielectric layer is usually developed by applying higher anodizing voltages (∼1000 V), 38 dramatically reducing the capacitance value due to the high dielectric layer thickness and the sealing of the tunnel pits.…”

Research progress on the preparation of anode foil oxide film for aluminum electrolytic capacitors

“…The hydration process is a crucial step before the formation, which has a very positive sign on reducing the energy consumption of anodic oxidation [2] and improving the performance of oxide film [3,4] . Scaduto, G. et al [3] studied the effect of alcohol solutions on the hydration process.…”

“…et al [4] found that extending the hydration time in boiling water helped prepare crystalline hydrated oxide films on high-purity aluminum substrates. The crystallinity of the anodic oxide film increases with increasing hydration time in a specific time range and increases the unit-specific capacitance of the electrode foil, the XRD image of which is shown in Figure 4 [4] . However, a longer hydration process can cause problems such as pore blockage and slow processing efficiency of the product.…”