Establishment of anhydrous synthesis process using molten salts as reaction media

点击翻译按钮获取中文摘要

The purpose of this project is to establish the anhydrous synthesis process that consists of purification of molten slats and separation/recovery of products. In year 1999, we succeeded in reducing the size of electrolysis cell to one half and the volume of molten salts to one tenth. In year 2000, we constructed a new electrolysis cell in an argon glove box having a gas purification equipment. By using this apparatus, it was found that water contamination level in LiCl-KCl melts could be reduced to one tenth compared to a conventional preparation method. In LiCl-KCl-DyCl_3 melts, a DyNi_2 film having 60 μm thickness was formed by potentiostatic cathodic electrolysis at a Ni electrode for 2 hours at 723 K. In LiCl-KCl-SmCl_3 melts, a SmNi_2 film having 20μm thickness was formed by galvanostatic cathodic electrolysis at a Ni electrode for 1hour at 723 K. In year 2001, we synthesized and/or searched for new room-and middle-temperature molten salts. At middle temperature range (200-300℃), it was found that the melting point of LiBr-KBr-CsBr was around 230℃, which was the lowest value among molten alkali halides. When LiH was added to this melt, it was found that hydride ion was formed. By using the electrode reaction of hydride ions, hydrogen absorption properties were evaluated for Ti electrode. At room temperature range, we succeeded in synthesizing a novel room temperature molten salt, EMIF-2.3HF, that has the highest conductivity among all room temperature molten salts at 25℃. It was found that EMIF-2.3HF had a electrochemical window of about 3.2 V. A high performance capacitor was constructed by using this melt.