CN-122013253-A - Voltage control method

Abstract

The embodiment provides a voltage control method for recovering valuable materials from an electrochemical device, which can inhibit the generation of large current. The voltage control method according to an embodiment is a voltage control method for recovering valuable substances from an electrochemical device including an electrode having a catalyst containing a noble metal by applying a voltage to the electrochemical device and periodically reversing the polarity of the voltage by holding the absolute value of the voltage after increasing with time, and performing an electrolytic reaction.

Inventors

• Jin Cunxiang is flat
• FUJIMAKI TAKURO

Assignees

• 株式会社东芝
• 东芝能源系统株式会社

Dates

Publication Date

20260512

Application Date

20250718

Priority Date

20241112

Claims (5)

1. 1. A voltage control method for recovering valuable substances from an electrochemical device provided with an electrode having a catalyst containing a noble metal by applying a voltage to the electrochemical device and periodically reversing the polarity of the voltage to perform an electrolytic reaction, The polarity of the voltage is periodically reversed by maintaining the absolute value of the voltage over time.
2. 2. The voltage control method according to claim 1, comprising: A first period in which the voltage value is maintained after the voltage value is linearly or curvilinearly reduced from a first value to a second value lower than the first value, and In a second period, the voltage is maintained after the value of the voltage is linearly or curvedly increased from a third value which is the same as or different from the first value to a fourth value which is higher than the third value.
3. 3. The voltage control method according to claim 2, wherein a third period during which the voltage is not applied is provided between the first period and the second period.
4. 4. The voltage control method according to claim 2, wherein, In the first period, the time required from the first value to the second value of the voltage is 0.6 seconds or more, In the second period, the time required from the third value to the fourth value of the voltage is 0.6 seconds or longer.
5. 5. The voltage control method of claim 1, wherein the catalyst comprises at least one noble metal selected from the group consisting of platinum, iridium, ruthenium, rhodium, palladium, platinum, gold, and rhenium.

Description

Voltage control method Reference to related applications The present application enjoys priority of Japanese patent application No. 2024-197478 (application date: 11/12 of 2024). The present application includes the entire content of the basic application by referring to the basic application. Technical Field Embodiments of the present invention relate to a voltage control method. Background With the development of worldwide carbon-neutral society, hydrogen is attracting attention as a substitute for fossil energy. In society where hydrogen is used for various purposes, an electrochemical device such as a water electrolysis device for producing hydrogen by electrolysis of water or a fuel cell for generating electricity using the obtained hydrogen is important. There are various modes of the water electrolysis device and the fuel cell depending on the operating temperature and the device structure. Among them, PEM-type water electrolysis apparatuses and solid polymer fuel cells (PEFC) in which a solid polymer membrane is used as an electrolyte and a noble metal is used as an electrode catalyst are expected to be further popularized because of their compact structure and low-temperature operation. The PEM-type water electrolysis apparatus and PEFC have very similar structures, and a Membrane Electrode Assembly (MEA) having electrode catalysts coated on both sides of a solid polymer membrane is used. In the future, with the development of social hydrogen socialization, the number of PEM-type water electrolysis devices and PEFCs on the market has increased, but the total amount of noble metal used in the electrode catalyst has also increased. Therefore, in order to spread these devices, it is necessary to ensure a sufficient amount of noble metal. One of the methods for securing the amount of noble metal is to recycle the PEM-type water electrolysis apparatus and PEFC after use to recover the noble metal. Recovery of precious metals present in high concentrations in waste products is expected to reduce supply costs compared to recovery of precious metals contained in very low concentrations in ore. In addition, by recovering uneven resources from waste products, raw materials can be stably supplied, and products can be continuously manufactured. As a method for recovering noble metals from fuel cells, it is common to burn waste in an incinerator or the like, dissolve noble metal components contained in ash with a strongly oxidizing solution such as aqua regia, and separate and recover the noble metal components (japanese patent No. 1626036). Further, as a simpler and environmentally friendly method, a technique for dissolving and recovering noble metals from fuel cells by electrolysis has been developed (patent documents 2, 3, and 4), and further development of a recycling technique for fuel cells is expected in the future. Since the noble metal dissolution technique from MEA based on electrolysis described in japanese patent No. 6652518, japanese patent No. 6652454, and japanese patent No. 6109769 can easily dissolve noble metals that are not normally dissolved using dilute hydrochloric acid at room temperature, social installation is expected as a method with low environmental load. In the electrolysis method used herein, unlike the usual electrolysis performed at a constant voltage or a constant current, the noble metal is dissolved by periodically reversing the polarity of the applied voltage. When a voltage is applied to the electrochemical device from the outside, a non-faradaic current associated with charging of the electric double layer at the interface between the electrolyte and the electrode and a faradaic current associated with progress of the electrochemical reaction are observed. The non-faraday current flows at the instant of applying the voltage, and when the charging at the interface is completed, no flow thereafter, and only faraday current caused by the electrochemical reaction is observed (north village house man, "chronoamperometry", electrochemistry,68, no.1, p.63-68 (2000)). When electrolysis is performed in which the polarity of the applied voltage is periodically reversed, a non-faraday current flows at the moment of each polarity switching. As the electrode area increases, the amount of electricity stored in the interface increases, and therefore, in a device using a porous body having a large electrode area as an electrode material, such as a PEM-type water electrolysis apparatus or PEFC, a large non-faraday current intermittently flows. Since the non-faraday current flowing immediately after the polarity inversion is very large compared with the faraday current, when noble metal dissolution by an electrolytic method is performed, it is necessary to prepare a power supply having a large output size capable of withstanding a current flow larger than the current actually used for noble metal dissolution. Japanese patent No. 6109769 shows an example in which electrolysis is performed b