Establishment of anhydrous synthesis process using molten salts as reaction media

本项目的目的是建立由熔板提纯和产品分离/回收组成的无水合成工艺。1999年，我们成功地将电解池的体积缩小到原来的一半，将熔盐的体积缩小到原来的十分之一。在2000年，我们建造了一个新的电解池在氩气手套箱有气体净化设备。通过使用该装置，发现与传统制备方法相比，LiCl-KCl熔体中的水污染水平可以降低到十分之一。在LiCl-KCl-DyCl_3熔体中，用Ni电极在723 K下恒电位阴极电解2小时，形成了厚度为60 μm的DyNi_2膜。在LiCl-KCl-SmCl_3熔体中，用Ni电极在723 K下恒流阴极电解1小时，形成了厚度为20μm的SmNi_2膜。2001年，我们合成和/或寻找了新的室温和中温熔盐。在中温范围（200 ~ 300℃），LiBr-KBr-CsBr的熔点在230℃左右，是熔融碱卤化物中熔点最低的。当LiH加入到熔体中时，发现形成了氢化物离子。利用氢化物离子的电极反应，对钛电极的吸氢性能进行了评价。在室温范围内，我们成功合成了一种新型的室温熔盐，EMIF-2.3HF，在25℃时，它的电导率是所有室温熔盐中最高的。发现EMIF-2.3HF的电化学窗口约为3.2 V。利用该熔体制备了高性能电容器。

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.