Comparative study on carbon corrosion characteristics of gas diffusion layer in PEMFCs under two accelerated stress tests

As a key component of proton exchange membrane fuel cell, the durability of gas diffusion layer (GDL) is directly related to the overall life of fuel cell. Carbon corrosion is a critical factor influencing the durability of GDL, damaging its pore structure and reducing its hydrophobicity, thus affecting the internal water management of fuel cells. At present, although there are many accelerated stress testing (AST) methods for studying carbon corrosion, there is a lack of indicators between these methods to comprehensively compare and analyze the corrosion of GDL. Herein, two ASTs, i.e., steady-state durability testing at a constant-potential of 1.4V (vs. RHE) and dynamic testing of a voltage triangular-wave of 1~1.5V (vs. RHE), are used to assess the durability of cathode GDL. The results reveal that the variation rates of pore volume and hydrophobicity of GDL after 6000 cycles of triangular-wave AST are faster than those after 24hours of constant-potential AST. By comparing the variation rates of oxygen mass transfer resistance and mass transfer impedance (Rmt) of GDL, it is found that the corrosion rate of triangular-wave AST is 6.75 times higher than that of constant-potential AST under the same corrosion degree.