气体扩散层中聚四氟乙烯的分布对质子交换膜燃料电池水淹的影响(英文)

Effect of polytetrafluoroethylene distribution in the gas diffusion layer on water flooding in proton exchange membrane fuel cells

通过在不同真空度下进行碳纸的聚四氟乙烯(PTFE)浸渍处理,考察了PTFE在碳纸中的分布对燃料电池水淹情况的影响.碳纸PTFE浸渍过程中,抽真空作用可以将碳纸微孔中存留的空气移除,使PTFE更均匀地扩散到内部微孔中.碳纸的断面电镜照片显示真空浸渍可以改善PTFE的分布.在总浸渍量相同时,由于真空浸渍使更多的PTFE进入到碳纸内部微孔,故其表面的PTFE比例减少.实验进一步考察了碳纸中亲水孔和憎水孔的分布,结果表明真空浸渍处理的碳纸具有更高比例的憎水孔.将不同处理方法的碳纸制备成膜电极,通过全尺寸电池考察其性能,结果表明PTFE的均匀分布可以改善电池性能,并且电化学阻抗分析表明其有利于改善水淹问题.

The effect of polytetrafluoroethylene （PTFE） distribution in the gas diffusion layer on water flooding in proton exchange membrane fuel cells was investigated. PTFE was introduced within micropores of carbon papers, to achieve hydrophobicity under different pressures. Carbon papers were sub-jected to vacuum conditions during immersion in PTFE solution to prepare gas diffusion layers. Residual gas within the carbon papers was eliminated, and PTFE evenly infused within the pores. Cross-sections of the carbon papers indicated that vacuum treatment improved PTFE distribution. The same PTFE content resulted in a decreased water contact angle of the carbon paper because of the greater PTFE content within the micropores. The proportions of hydrophobic and hydrophilic pores within the carbon papers were investigated. The proportion of hydrophobic pores increased during the vacuum treatment. Membrane electrode assemblies （MEAs） were fabricated using the treated hydrophobic carbon papers as gas diffusion layers and were evaluated in a full-sized fuel cell. The uniform PTFE distribution of the carbon paper benefited fuel performance. Electrochemi-cal impedance spectroscopy indicated that the improved MEA possessed favorable resistance to water flooding.