Study on the mechanism of ionic mobility in molten carbonate mixtures.

熔融碳酸盐混合物中离子迁移机制的研究。

基本信息

批准号：
07454183
负责人：
OKADA Isao
金额：
$ 4.54万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

The molten binary systems (Li, K)_2CO_3 and (Li, Na)_2CO_3 at their eutectic compositions are the candidates for the electrolytes for the molten carbonate fuel cells (MCFC). The internal mobilities in the system (Li, Na)_2CO_3 have been measured by countercurrent electromigration ; those in the system (Li, Na)_2CO_3 at were previously measured In the former system the mobility of Na^+ is somewhat greater than that of Li^+ at all the investigated range of composition and temperature. The internal mobilities of Li^+, u_<Li>, in these two systems are well expressed by the empirical equation : u_<Li>=[A/ (V_m-V_0)] exp (-E/RT), where V_m is the molar volume of the mixture ; V_0, A and E are constants nearly independent of the second cation. The mobilities in the ternary system (Li, Na, K)_2CO_3 at the eutectic composition (43.5-21.5-25.0 mol%) have also been measured. The order of the mobilities of these cations is as follows : u_<Li>-u_K<u_<Na> (at 500ﾟC), u_<Li><u_<Na>-u_K (at 600ﾟC) and u_<Li><u_<Na>-u_K (at 750ﾟC). These results can be interpreted in terms of the dynamic dissociation model previously presented by us. This suggests that the internal mobilities of other cations could be semi-quantitatively predicted by this model. Polarized Raman spectroscopy has been applied for systems (Li, Na)_2CO_3 to investigate the rotational relaxation of the C_<3V> axis of the CO_3^<2-> ion. No appreciable relation has been found between the mobility and the rotationa motion.

熔融二进制系统（LI，K）_2CO_3和（LI，NA）在其电子组合物处是熔融碳酸盐燃料电池（MCFC）的电解质的候选者。系统中的内部迁移率（LI，NA）_2CO_3是通过反电流电气迁移测量的； those in the system (Li, Na)_2CO_3 at were previously measured In the former system the mobility of Na^+ is somewhat greater than that of Li^+ at all the investigated The internal mobilities of Li^+, u_<Li>, in these two systems are well expressed by the empirical equation : u_<Li>=[A/ (V_m-V_0)] exp (-E/RT), where V_m is the molar volume of the mixture ; V_0，A和E是常数几乎与第二个阳离子无关。还测量了三元系统（Li，Na，k）_2CO_3在共晶组成（43.5-21.5-25.0 mol％）中的迁移率。这些阳离子的迁移率的顺序如下：u_ <li> -u_k <u_ <a>（在500 c），u_ <li> <u_ <u_ <na> -U_K（在600 c）和u_ <li> <li> <u_ <u_ <na> -u_k（在750 c）中。这些结果可以用我们先前提出的动态解离模型来解释。这表明其他阳离子的内部迁移率可以由该模型半定量地预测。偏振拉曼光谱已用于系统（LI，NA）_2CO_3，以研究CO_3^<2->离子的C_ <3v>轴的旋转松弛。在迁移率和旋转运动之间未发现可欣赏的关系。