NaF含量对惰性阳极在低温电解质中电化学性质的影响

Effect of different contents of NaF on electrochemical properties of inert anodes in low-temperature electrolyte

惰性阳极在NaF含量分别为12 wt%、18 wt%.25 wt%的NaF-KF-A1F3-7 wt%A12O3电解质体系中电解时,阳极表面的电化学反应进行的程度呈先增大后减小的趋势,阳极过电位呈逐渐增大的趋势,氧化铝的溶解度呈逐渐降低的趋势。以0.5A/cm^2的电流密度进行恒电流电解时,该惰性阳极在18 wt%NaF-KF-A1F3-7 wt%A12O3电解质中电解的持续时间最长最平稳。NaF含量过高或过低时,阳极寿命均会降低。电解质中的氟元素在电解过程中会渗透到阳极氧化膜的最里层,形成金属氟化物,不利于电解。

When the inert anode is electrolyzing in the low-temperature electrolyte of NaF-KF-A1F3-7 wt%A12O3 with different contents of NaF(12wt%,18wt%and 25wt%),the electrochemical reaction level on the anode surface exhibits a downward trend after an upward increase at first,the anode overpotential demonstrates a gradually-increasing trend,and the alumina solubility shows a gradually-decreasing trend.In the constant current electrolysis at the current density of 0.5A/cm2,the electrolysis of inert anodes in the 18 wt%NaF-KF-A1F3-7 wt%Al203 electrolyte lasts for the longest time and most stably.The service life of anodes will be reduced if the NaF content is excessively high or excessively low.The fluoride in electrolyte permeates the most inner layer of anode oxide during the electrolysis process to form metal fluoride,which is unfavorable to electrolysis.