亚硫酰氯阴极还原的半对数极化曲线

THE TAFEL PLOT OF THIONYL CHLORIDE REDUCTION

目前正在广泛研究的鲤/亚硫酰氯(Li/SOCl_2)电池是迄今为止比能量最高的一种新型化学电源。提高电池的性能和可靠性与电池反应的化学和电化学性质直接有关。但是,SOCl_2的还原过程相当复杂,对其反应机理迄今尚无明确的结论。由于SOCl_2还原时伴随着LiCl的沉积,当用常规电极测量时难以得到稳态极化曲线,因而至今未见报道SOCl_2还原反应的半对数极化曲线。微电极的单位表面上极限液相传质速度较高,且测量时较易得到稳态电流。因此,采用微电极方法可在一定程度上避开上述困难,研究SOCl_2还原反应的机理。

The electrochemical behaviors of thionyl chloride reduction in 0.11 mol dm^(-3) SOCl_2+ 0.1 mol dm^(-3) LiA1CI_4/DMF solution were studied with disc microelectrodes. For the first time, satisfactory Tafel plot with slope very nearly to 120mV/decade was obtained from steady polarization curve of thionyl chloride reduction. By analysis of the Tafel plot, it is clear that the first electron transfer of thionyl chloride reduction is a totally irreversible. The exchange current density of the first electron transfer of thionyl chloride reduction is 9.0×10^(-7)A cm^(-2), and a value very near to 0.5.