微孔层在质子交换膜燃料电池中起着水-气-热-电传输的重要作用,在机械应力作用下的变形及微结构的破坏将严重影响这种传输作用。本文首先实验制备微孔层并进行表征,量测其应力-应变关系。然后基于实验表征获得的特性参数,随机数值重构出微孔层的三维微观结构。使用有限元方法模拟其在不同机械作用下的形变,分别获得碳颗粒和聚四氟乙烯(PTFE)在不同应变下的位移-应力分布。结果表明：机械作用会使微孔层微结构产生显著应变,且位于应力施加侧表面应力和应变最大,更易产生应力集中现象。随着机械应变的增加,在受力方向上,应力会呈指数形式增大。当应变为10%时,碳颗粒和PTFE上的应力的最大值约为31.385 MPa和14.873 MPa。当应变增加到40%时,应力的最大值变为160.03 MPa和96.165 MPa,此时应力集中最为明显。微孔层中应力集中区域会随着应变的增大而明显变大。

The microporous layer plays an important role in the transmission of water, gas, heat and electricity in proton exchange membrane fuel cells,The deformation and microstructure damage under mechanical stress will seriously affect the transmission. The relationship between stress and strain is first obtained experimentally after fabricating the microporous layer and characterizing its microstructural properties. Then, the microstructure of the microporous layer is reconstructed numerically based on the microstructure characteristic parameters obtained from the experimental characterization. The displacement-stress distributions of carbon particles and polytetrafluoroethylene under different mechanical strains are obtained using finite element method. The results show that the mechanical action causes significant strain to the microporous layer microstructure of PEMFC, and strain located on the microporous layer surface is maximum, which is more likely to produce stress concentration. With the increase of mechanical strain, the stress increases exponentially in the direction of stress. When the strain is 10%, the maximum stress on carbon particles and PTFE is about 31.385 MPa and 14.873 MPa. When the strain increases to 40%, the maximum stress becomes 160.03 MPa and 96.165 MPa, and the stress concentration is the most obvious. The stress concentration area in the microporous layer will obviously increase with the increase of strain.

国家自然科学基金资助项目(52306270, 22179103, 21676207)；广东省基础与应用基础研究(2022A1515110456)