镀铌不锈钢双极板的电化学性能

Electrochemical Characteristic of Stainless Steel Bipolar Plates Deposited with Niobium

采用对水和空气稳定的氯化胆碱:乙二醇=1:2(摩尔比)的离子液体为电解质,在316不锈钢基体上进行电镀铌,考察模拟质子交换膜燃料电池(PEMFC)环境中镀铌不锈钢双极板的电化学性能。结果表明,以氯化胆碱类离子液体为电解质在316不锈钢表面可获得平整均匀的颗粒状铌镀层。在模拟质子交换膜燃料电池环境中,镀铌316不锈钢的腐蚀电位得到提高,维钝电流密度减小,阳极极化性能得到改善;孔蚀电位正移,反应电阻增大,耐蚀性能提高。能谱和X射线衍射分析结果表明,镀铌后316不锈钢表面生成化学惰性良好的NbO和Nb2O5,形成耐蚀"屏障",改善了不锈钢表面膜的钝化能力,提高了不锈钢的电化学稳定性能。

Niobium was electrodeposited on 316 stainless steel in water and air-stable choline chloride based ionic liquid （choline chloride： ethylene glycol=1：2 （mole ratio））. The electrochemical characteristic of the coated steel was investigated in simulated proton exchange membrane fuel cell （PEMFC） environment. The results indicated that the uniform film was obtained on stainless steel surface. In simulated PEMFC environment, after 316 stainless steel was coated with niobium, its electrochemical characteristics were improved greatly, such as the corrosion potential increased, the passivation current density decreased, the pitting potential moved toward positive, and the reaction resistance increased. The deposited niobium film was mainly composed of Nb, NbO and Nb2Os, among them NbO and Nb205 behaved as an anti- corrosion barrier and improved the passavition ability of surface layer. So the electrochemical stability of the stainless steel bipolar plate was increased remarkably.