固态氧化物阴极过程的离子扩散模型及其Ta_2O_5熔盐电解验证

An Ionic Diffusion Model for the Solid Oxide Cathode and Its Verification by the Electrolysis of Ta_2O_5 in Molten CaCl_2

固态氧化物阴极在氯化钙熔盐电解质中的脱氧速率可依据氧离子的稳态扩散模型(PRS模型)由固态氧化物阴极孔隙率P,还原后金属与还原前氧化物之间的摩尔体积比R,还原后阴极的体积收缩率S等参数直接计算.PRS模型重要意义还在于可提供极简单的公式以预测不同金属氧化物还原时固态阴极的优化孔隙率,而固态阴极孔隙率对其脱氧速率有显著影响.对于Ta2O5电解,其固态阴极孔隙率不宜大于50%.相关理论预测结果得到了固态Ta2O5在氯化钙熔盐中电解实验的良好验证,表明PRS模型对固态化合物阴极的快速、高效电解具有重要的指导意义.

The deoxidation speed of a solid oxide cathode in molten CaCl2 can be estimated by the PRS steady diffusion model of O2-,which correlates the deoxidation speed with the precursor porosity,P,the metal-to-oxide molar volume ratio,R,and the cathode volume shrinkage S.The PRS model indicates that the porosity of the oxide cathode has important influence on the deoxidation speed,and provides a very simple equation for the prediction of the optimal cathode porosity.For the electrolysis of Ta2O5,the porosity of the cathode is better to be within 50%.The model and its predictions have been well verified by the electrolysis of solid Ta2O5 in molten CaCl2,suggesting the great significance of the PRS model for the high speed and high current efficiency electrolysis of solid compound cathode in molten salts.