钙离子对质子交换膜燃料电池性能衰减机理研究

STUDY ON DEGRADATION MECHANISM OF PROTON EXCHANGE MEMBRANE FUEL CELL PERFORMANCE BY PRESENCE OF Ca

采用试验方法,通过向质子交换膜燃料电池(PEMFC)的电极(阳极和阴极)注入2种浓度(200和500 mg/L)的Ca2+溶液,研究Ca2+对PEMFC电化学性能的影响;通过扫描电镜(SEM),能量散射谱仪(EDS)和电子探针(EPMA)对经Ca2+污染20 h后的电池性能的衰减机理进行研究。实验结果表明,经200和500 mg/L Ca2+污染PEMFC阳极20 h后,电池的电化学性能衰减明显,随着Ca2+浓度的增加,电池电化学性能衰减程度增大;SEM和EDS实验结果表明,经500 mg/L Ca2+污染PEMFC阳极20 h后,阴、阳两极的气体扩散层分别与阴、阳两极的催化层剥离,在质子交换膜、阳极催化层、阳极气体扩散层以及阴极气体扩散层均发现Ca元素,在质子交换膜上Ca元素含量高于其他部件上;EPMA实验结果表明,Ca2+污染PEMFC阳极后,Ca元素主要存在于质子交换膜上;研究结果表明,PEMFC电化学性能衰减的机理主要是由于Ca2+与质子交换膜中的质子发生离子交换反应并取代质子交换膜中的磺酸根基团上的质子形成新的磺酸盐结构所致。

In this paper,based on the electrochemical performance tests,the effects of calcium ion(Ca2+)on the performance of proton exchange membrane fuel cell(PEMFC)were studied by adding two levels of Ca2+concentrations(i.e.200 and 500 mg/L)into the anode and cathode of the PEMFC.And then,scanning electron microscopy(SEM),energy dispersive spectrometer(EDS)and electron probe microanalysis(EPMA)were employed to study degradation mechanism of the PEMFC performance for 20 hours of the Ca2+contamination.The test results show that the electrochemical performance of the PEMFC degraded for contamination by 200 and 500 mg/L Ca2+for 20 hours in the anode of PEMFC,and the degradation of the PEMFC performance was more serious with the increasing Ca2+concentration.The SEM and EDS test results show that the membrane electrode assembly(MEA)degraded after contaminated by 500 mg/L Ca2+for 20 hours,and the anode and cathode gas diffusion layers of the MEA separated from the anode and cathode catalyst layers of the MEA,respectively.Calcium was found in the proton exchange membrane,anode catalyst layer,anode and cathode gas diffusion layers,and the content of Calcium in the proton exchange membrane was higher than that in other parts of the MEA.The EPMA test results show that Calcium mainly appeared in the proton exchange membrane after the MEA were contaminated by 200 mg/L Ca2+for 20 hours in the anode of PEMFC.The degradation mechanism of PEMFC performance for the Ca2+contamination could be due to ion exchange reaction between Ca2+cation and the proton of sulfonate group of proton exchange membrane to form new sulfonate structure.