Ca杂质对Na-β″-Al_2O_3在钠硫电池中退化的影响

Effects of Calcium Impurities on the Degradation ofβ″Alumina Utilized in Sodium-Sulfur Cells

研究了钠硫电池中 β″-Al_2O_3固体电解质、钠电极和硫电极的 Ca 杂质对 β″-Al_2O_3电性能退化的影响。用电子探针分析检测了电池失效后,β″-Al_2O_3陶瓷管在两个电极之间表面的 Ca 杂质。Ca 杂质主要存在于β″-Al_2O_3的内表面,即在 β″-Al_2O_3/Na 电极界面。试验表明硫电极中的 Ca 杂质(<60 ppm)对钠硫电池电阻随工作循环周次的升高在早期没有影响。在钠硫电池工作过程中,结合 β″-Al_2O_3电解质中的 Ca 杂质最有害于 β″-Al_2O_3的电导及其强度的退化,讨论了电池在充放电过程中 Ca 杂质对 β″-Al_2O_3电阻增加及其损坏的影响机理。

The effects of calcium impurities in beta″-alumina solid electrolytes on the de-gradation of beta″-alumina utilized in sodiumsulfur cells were studied.After thecells were in failure,calcium impurities on the surfaces of beta″-alumina ceramicstubes between two eletrodes were easily detected by EPMA.Significant calcium impuri-ties were discovered upon the beta″-alumina inner surface,that is a beta″-alumina/sodium interface in sodium-sulfur cell.it can be shown that calcium impurities lessthan 60 ppm in the sulfur electrods are not detrimental unable to cause an increasein cell discharge resistance with time of cycling during initial stage.But calcium im-purities,incorporated into beta″-alumina solid electrolytes,can lead to serious degra-dation in both conductivity and strength of beta″-alumina in the sodium-sulfur cells.Some mechanisms for the increase in resistance of beta″-alumina electrolyte withtime of cycling in the sodium-sulfur cell and also leading to earlier failure due tocalcium impurities have been discussed.