Method for producing electrode for aluminum electrolytic capacitor

Abstract

When manufacturing an electrode for an aluminum electrolytic capacitor, in the first hydration treatment step (ST1), the aluminum electrode having a porous layer is immersed in a first hydration treatment solution at a temperature of 80° C. or higher to form a hydration film on the aluminum electrode , in the dehydration step ( ST2 ), the aluminum electrode is heated in an atmosphere having a temperature of 150° C. or higher and 350° C. or lower. Next, in the second hydration treatment step (ST3), after immersing the aluminum electrode in the second hydration treatment solution at a temperature of 80° C. or higher to form a hydration film on the aluminum electrode, in the chemical conversion step, the aluminum electrode is treated The chemical conversion is carried out up to a voltage of 400V or higher, further 600V or higher.

Description

technical field [0001] The present invention relates to a method for producing an electrode for an aluminum electrolytic capacitor by chemically converting an aluminum electrode. Background technique [0002] As a method of manufacturing an electrode for an aluminum electrolytic capacitor for medium and high voltages, it is known to perform a hydration treatment step of boiling an aluminum foil in pure water (pure water boiling step) before performing a chemical conversion step. By performing the hydration treatment step, the electrostatic capacity after chemical conversion can be increased. This is because a highly crystalline chemical conversion coating can be obtained when pseudo-boehmite or the like in the hydration coating is dehydrated and converted into a chemical conversion coating. When the hydrated film is obtained only through the general hydration treatment steps, the amount and thickness of the hydrated film will be increased by prolonging the boiling time, and...

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Problems solved by technology

[0003] However, if the boiling time is prolonged to increase the thickness or amount of the hydrated film, it will cause the porous part of the aluminum electrode to be blocked by the hydrated film.

If the clogging occurs due to the hydration coating, the electrolyte cannot penetrate into the clogged part during the subsequent chemical conversion, and the chemical conversion coating cannot be properly formed, resulting in a decrease in the hydration resistance of the chemical conversion coating

Also, the surface area of ​​the clogged part is reduced, so the electrostatic capacitance is reduced

In particular, when the thickness of the porous layer is 400 μm or more, the porous part is likely to be clogged due to boiling, so if the boiling time is prolonged to increase the electrostatic capacitance, the hydration resistance of the chemical conversion coating will deteriorate and the electrostatic capacitance will also decrease. The problem

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