造孔剂对PEMFC膜电极性能的影响

Influence of pore forming agents on the performance of membrane electrode assembly in PEMFC

在质子交换膜燃料电池(PEMFC)膜电极的催化层中加入造孔剂以减小气体反应物的扩散传质阻力。提出了两种新型造孔剂,分别为低分解温度的NH_4HCO_3和高溶解度的(NH_4)_2SO_4。实验结果表明,加入适量的造孔剂NH_4HCO_3,可使膜电极在H2-空气条件下的输出功率获得显著提高;加入适量的造孔剂(NH_4)_2SO_4,可使膜电极大电流工作时的性能得到明显改善。环境扫描电镜(ESEM)的测试结果表明,造孔剂的加入使膜电极催化层的孔结构得到优化,更有利于传质过程的顺利进行和提高催化剂Pt的利用率。

An effective method of minimization of the gas diffusion transport resistance was to exploit suitable pore-forming agents in the formulation of the electrocatalytic layer of the membrane electrode assembly (MEA) in a proton exchange membrane fuel cell (PEMFC). Two kinds of new pore-forming agents, NH4HCO3 and (NH4)2SO4, were studied in this paper. The results showed that the electrochemical performance of MEA with suitable amount of NH4HCO3 additive was improved obviously for air and oxygen operations. The cell voltage of MEA with suitable amount of (NH4)2SO4 additive was increased at large current densities for air operations. The pore structure of the catalyst layer in a MEA was investigated by the environmental scanning electron microscopy (ESEM) method, and the measurement results showed that higher porosities were obtained in the catalyst layer with the two additives. This was of benefit to enhance the mass transfer of oxidants and utilization of electrocatalysts.