Passive Films for Electrolytic Capacitors

Ono, Satoshi

doi:10.1016/b978-0-12-409547-2.13412-2

Cited by 5 publications

(13 citation statements)

References 47 publications

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“…Using these cell parameters, the cell-to-pore diameter ratio (dcell/dpore) of the anode films formed in both sulfuric and oxalic acids at different constant voltages was plotted against the logarithm of the current density (log j), and a linear relationship was found [15]. Since the electric field E across the barrier layer of the porous film varied linearly with log j, as in the case of the barrier-type film [17,19], the dcell/dpore ratio was considered to be proportional to the electric field. From these results, it was deduced that the barrier layer thickness and cell diameter were proportional to the voltage and inversely proportional to E, whereas the pore diameter was proportional to the voltage and inversely proportional to the square of E. This result clearly shows that the pore size depends more strongly on the current density than on the other cell parameters.…”

Section: Cell Parametersmentioning

confidence: 99%

“…Therefore, the higher the electric field and the larger the negative charge of the anions in the oxide film, the smaller their size, and the smaller their interaction with the oxide, the greater the number of anions incorporated deeper into the barrier layer. The anion content of porous anodic films linearly increases with the increasing log of the current density, i.e., electric field strength [ 15 ], similar to the case of barrier-type films [ 17 , 19 , 59 ]. It is shown that the anion content and species significantly affect the film properties [ 23 , 36 , 68 , 71 , 72 , 73 ].…”

Section: Incorporation Depth and Content Of Electrolyte Anionsmentioning

confidence: 99%

“…It is shown that the anion content and species significantly affect the film properties [ 23 , 36 , 68 , 71 , 72 , 73 ]. In barrier-type films, the anion species and the content of anions have a significant impact on the permittivity, as well as the leakage current, due to the formation of defects [ 17 , 18 , 19 , 74 , 75 ].…”

Section: Incorporation Depth and Content Of Electrolyte Anionsmentioning

confidence: 99%

“…The presence of defects that are ignored in modeling, as well as the factors that cause them, appeared to be an important and fascinating issue. The author has also studied the structure and properties of barrier-type films as a basis for elucidating the formation behavior of porous films [ 17 ]. As a result, the author realized that not only the geometric structure of the film but also the anion incorporation has a significant impact on the film’s dielectric properties [ 17 , 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

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Nanostructure Analysis of Anodic Films Formed on Aluminum-Focusing on the Effects of Electric Field Strength and Electrolyte Anions

Ono

2021

Molecules

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In this review, the research conducted by the authors on anodic oxide films on aluminum is described, paying particular attention to how the electric field strength, as a factor other than voltage, controls the nanostructures and properties of the films. It will also be indicated what factors contribute to the formation of defects, which, in contrast to the ideal or model film structure, contains a significant number of defects in the film. In addition to electrochemical measurements, the films were examined with a variety of advanced instruments, including electron microscopes, to confirm the “reality of film nanostructure” from a slightly different angle than the conventional view. The following topics on anodic films formed in four types of major anodizing electrolytes are discussed: pore initiation process, steady-state porous structure, sealing mechanism, the relationship between cell parameters and voltage/electric field strength, amount and depth of anion incorporation, electrolyte types, radial branching of pores, atypical pore structures, defect formation mechanism, self-ordering, Al coordination number, and the creation of α-alumina membranes.

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Section: Cell Parametersmentioning

confidence: 99%

Section: Incorporation Depth and Content Of Electrolyte Anionsmentioning

confidence: 99%

Section: Incorporation Depth and Content Of Electrolyte Anionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nanostructure Analysis of Anodic Films Formed on Aluminum-Focusing on the Effects of Electric Field Strength and Electrolyte Anions

Ono

2021

Molecules

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“…Niobium oxide is an n-type semiconductor with a band gap of ~3.4 eV and, as it is a transparent dielectric material, it is ideal for capacitor technology. The value of the dielectric constant ε given in the literature is 41 [ 2 , 3 ]. One of the first descriptions of niobium oxide film growth in aqueous acidic solution was given by Young [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Determination of the Dielectric Constant of Niobium Oxide by Using Combined EIS and Ellipsometric Methods

Fitzner

Stępień

2023

Materials

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Combining ellipsometric and EIS methods, the dielectric constant ε for the oxide Nb2O5 at room temperature was determined. At first, the linear dependence between anodization voltage and oxide thickness was established in the form d = 2.14 (± 0.05) × U + 12.2 (± 1.7) nm in the range of anodizing potentials 0–50 V. Next, assuming the equivalent circuit corresponds to one, the capacitance C of the dense oxide layer was measured. All results taken together gave the value of dielectric constant ε = 93 ± 5.

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

Quintero,

Matsuya,

Iwai

et al. 2024

ACS Appl. Mater. Interfaces

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Aluminum solid polymer capacitors are promising devices for the increased demand for power electronics applications. Nonetheless, the low breakdown voltage of commercially available catalysts (∼100 V) limits their applications. In this study, a hydroxide-film-covered high-purity aluminum was anodized at 700 V in boric acid at 85 °C, and the effect of a second hot water immersion (posthydration treatment) after anodizing on the breakdown voltage was studied as a possible future treatment to enhance the withstand voltages of solid electrolytic capacitors. The dielectric breakdown voltage of the anodized aluminum with a PEDOT:PSS coating was ∼500 V, being ∼200 V less than the anodizing voltage; however, the dielectric breakdown voltage was increased above 700 V by introducing the posthydration treatment due to the formation of a nanovoid layer above the dielectric alumina film. Our research suggests that the highly dispersed nanovoids incorporated with PEDOT:PSS avoid the current concentration at some local regions, effectively increasing the dielectric breakdown voltage. The posthydration treatment increased the leakage current by introducing physical defects in the dielectric film. However, the leakage current was reduced by a voltage sweep below the breakdown voltage after the PEDOT:PSS coating or a second anodizing process before the coating, keeping the breakdown voltage above 600 V. A promising processing route to obtain aluminum solid capacitors with high withstand voltage (600 V) found in our research is, first, dipping in hot water; second, anodizing at 700 V; then a second hot water treatment; and a second anodizing at 400 V, which keeps the capacitance invariable with a breakdown voltage enhanced.

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Passive Films for Electrolytic Capacitors

Cited by 5 publications

References 47 publications

Nanostructure Analysis of Anodic Films Formed on Aluminum-Focusing on the Effects of Electric Field Strength and Electrolyte Anions

Nanostructure Analysis of Anodic Films Formed on Aluminum-Focusing on the Effects of Electric Field Strength and Electrolyte Anions

Determination of the Dielectric Constant of Niobium Oxide by Using Combined EIS and Ellipsometric Methods

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

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