Characterization of the Cathodic Thermal Behavior of Molten CaCl2 and Its Hygroscopic Chloride Mixture During Electrolysis
Characterization of the Cathodic Thermal Behavior of Molten CaCl2 and Its Hygroscopic Chloride Mixture During Electrolysis
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DOI：
10.1149/1945-7111/ab9961
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发表时间：
2020-06
影响因子：
3.9
通讯作者：
Ryota Shibuya;S. Natsui;H. Nogami;T. Kikuchi;R. Suzuki
中科院分区：
文献类型：
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作者：
Ryota Shibuya;S. Natsui;H. Nogami;T. Kikuchi;R. Suzuki
在CaCl2或其氯化物熔体中电化学沉积的液态金属是活性金属氧化物的有效还原剂。虽然可以在很高的电解效率下获得很低的氧浓度，但由于熔融氯化物中存在着很难检测到的少量水杂质，导致电解效率较低。在这项研究中，为了阐明在微吸湿的LiCl-KCl-CaCl2熔体中阴极电极的形态和热特性，我们同时进行了电化学测量和热测量，使用插入钼电极(I.D.1.57毫米)。同时，使用同步高速数码相机以500-μ的S间隔记录电极界面的变化。尽管体系中含有少量的水，但测得的吸热量远小于热力学预测，这表明生成的氢通过氢化物的形成降低了阴极表面电沉积的液态合金的纯度。通过同步热测量，可以快速、灵敏地跟踪杂质水电沉积模式的变化，而这一变化仅通过电化学电位-电流响应是很难确定的。
A liquid metal electrochemically deposited in CaCl2 or its chloride melts serves as an effective reductant for active metal oxides. Although a very low oxygen concentration can be achieved at a considerably high electrolysis efficiency, the existence of small amount of water impurity in molten chlorides, which is very difficult to detect, causes low electrolysis efficiency. In this study, to clarify the morphological and thermal characteristics of a cathodic electrode in a slightly hygroscopic LiCl–KCl–CaCl2 melt, we simultaneously performed electrochemical measurements and thermal measurements using an ultrafine thermocouple inserted inside a Mo electrode (i.d. 1.57 mm). Concomitantly, changes in the electrode interface were recorded at 500-μs intervals using a synchronized high-speed digital camera. Despite the small amount of water included in the system, the measured heat absorption was much smaller than thermodynamically predicted, which suggested that the generated hydrogen decreased the purity of the liquid alloy electrodeposited on the cathode surface through hydride formation. By using the synchronized thermal measurement, it was possible to trace the change in the electrodeposition pattern of impurity water quickly and sensitively, which was difficult to determine in only the electrochemical potential-current response.