Effect of electrodepositing Ag on DC etching aluminum foils for electrolytic capacitor

Ban, Chaolei; Zhu, Shuqin; Hou, Jianhua; Wang, F. R.; Wang, J.

doi:10.1007/s10854-017-6385-9

Cited by 9 publications

(3 citation statements)

References 22 publications

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“…However, little attention was paid to the cubic tunnel model with branches. On another way, we have also found that both Zn and Ag nuclei were deposited on Al foil as pretreatment to induce tunnel etching perpendicular to Al surface (Ban et al, 2013c;Ban et al, 2017). The similar results were further verified by Peng et al who electrodeposited Zn nuclei on Al foil (Peng et al, 2015).…”

Section: Introductionsupporting

confidence: 77%

D.C. etching anode aluminum foil to form branch tunnels by electroless depositing Cu

Liu

Wang

Chen

et al. 2019

ACMM

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Purpose The purpose of this study is to explore the mechanism of branch pits and tunnels formation and increase the specific surface area and capacitance of anode Al foil for high voltage electrolytic capacitor by D.C. etching in acidic solution and neutral. Design/methodology/approach Al foil was first D.C. etched in HCl-H2SO4 mixed acidic solution to form main tunnels perpendicular to the Al surface, and then D.C. etched in neutral NaCl solution including 0.5 per cent C6H8O7 and Cu(NO3)2 with different concentration to form branch tunnels normal to Al surface. Between two etching, Cu nuclei were electroless deposited on the interior surface of main tunnels by natural occluded corrosion cell effect to form micro Cu-Al galvanic local cells. The effects of electroless deposited Cu nuclei on cross-section etching morphologies and electrochemical behavior of Al foil was investigated with SEM, polarization curve and electrochemical impedance spectroscopy (EIS). Findings The results show that sub branch tunnels can form along the main tunnels owing to the formation of Cu-Al micro-batteries, in which Cu is cathode and Al is anode. With increase in Cu(NO3)2 concentration, more Cu nuclei can be electroless deposited and serve as the favorable sites for branch tunnel initiation along the whole length of main tunnels, leading to enhancement in specific capacitance of anode Al foil. Originality/value Cu nuclei were electroless deposited on the interior surface of main tunnels by natural occluded corrosion cell effect to form micro Cu-Al galvanic local cells, which can serve as the favorable sites for branch tunnel initiation along the main tunnels to enhance specific capacitance of anode Al foil.

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Section: Introductionsupporting

confidence: 77%

D.C. etching anode aluminum foil to form branch tunnels by electroless depositing Cu

Liu

Wang

Chen

et al. 2019

ACMM

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“…8 Fortunately, we developed a polishing method enables counting the tunnel length. Many scholars have studied the effects of bath temperature, 8-10 current density, [10][11][12] and bath chemistry 3,[13][14][15][16][17] on tunnel growth. These factors have a clear impact on tunnel growth and have guided industrial production.…”

Section: Introductionmentioning

confidence: 99%

Effects of the solution flow rate on the growth of aluminum etch tunnels

You

Chen

et al. 2022

Engineering Reports

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Increasing the specific surface area of the anode foil of aluminum electrolytic capacitors is a research direction to improve the performance of capacitors. Industrial mass‐produced anode foil increases the specific surface area by electrochemical etching of the aluminum foil. However, the tunnels created by corrosion stop growing midway through this process. In this study, the effect of the solution flow rate on tunnel growth is investigated, and the growth of tunnels is analyzed using a new method of preparing oblique sections. Neater tunnels can be grown by increasing the solution flow rate to facilitate active tunnels.

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“…DC or AC etching is usually considered to be an effective method of increasing the surface area of aluminum foils. The growth of pits using high-purity aluminum during DC etching in hot HCl solutions has been investigated with respect to the effect of electrolyte conditions on the pit shape [1], morphology of the early stages of the pitting corrosion [2], the tunnel pit growth rate [3], the effect of impurities on the DC etching behavior [4,5], the influence on the etch pit width and tunnel length [6], the tunnel growth effect after preprocessing with polymeric corrosion inhibitor before DC etching [7], and other methods assisting DC etching [8].…”

Section: Introductionmentioning

confidence: 99%

Tunnel growth mechanism of aluminum foils during etching on corrosion cell

Xu¹,

Li²,

Wang³

2018

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The corrosion cell is exploited to enhance the effective surface area of high-purity aluminum foils for aluminum electrolytic capacitors by forming tunnels. The morphology of tunnels is characterized, and the growth mechanism is discussed. Detailed investigations indicate that tunnels could grow only when nitric acid was added into the mixed acid electrolyte in the corrosion cell. Also, the tunnel morphology in the aluminum foil is relevant to the concentration of nitric acid and hydrochloric acid. In the mixed electrolyte solution that consists of 3.0 mol L −1 H2SO4, 1.0 mol L −1 HCl solution and 0.2 mol L −1 HNO3, the current density of the corrosion cell on the aluminum foil surface can reach 0.2 A cm −2 , which leads to square tunnels of high density on the surface of aluminum foils. The length and width of the tunnels are about 25-30 and 2 µm, respectively. The morphology of the tunnels is similar to that obtained by DC etching. The current results indicate that the generation of tunnels has a close correlation with the hydrogen evolution corrosion and oxygen absorption corrosion in the corrosion cell.

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Effect of electrodepositing Ag on DC etching aluminum foils for electrolytic capacitor

Cited by 9 publications

References 22 publications

D.C. etching anode aluminum foil to form branch tunnels by electroless depositing Cu

D.C. etching anode aluminum foil to form branch tunnels by electroless depositing Cu

Effects of the solution flow rate on the growth of aluminum etch tunnels

Tunnel growth mechanism of aluminum foils during etching on corrosion cell

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