Before the start of fuel cell engin

Before the start of fuel cell engine, due to the diffusion through the anode exhaust channel and membrane electrode, there will be air in the anode flow field. When activated, hydrogen enters the anode and forms a hydrogen-air interface in the anode flow field. When the fuel cell shuts down, due to the concentration gradient, residual oxygen in the cathode flow field will diffuse through the proton exchange membrane to the anode, forming a hydrogen-air interface with the residual hydrogen there. In addition, when the fuel cell system is shut down, outside air penetrates the fuel cell through the anode channel, also causing the formation of the hydrogen-air interface. The specific processes above are schematically shown in Fig. 3 [12]. United Technologies Corporation (UTC) was the first to propose thepresence of hydrogen–oxygen interface in 2000. Reiser et al. [15] proposed in 2005 that the hydrogen-air interface formed inside the fuel cell would cause a high potential in the cathode, which in turn leads to corrosion of the catalyst carbon carrier. This reverse-current decay mechanism has been considered as the basis of PEMFC degradation during start and stop conditions. A one-dimensional steady-state model was proposed [15] to simulate the change of the liquid phase potential along the flow path in the electrolyte when the hydrogen-air interface is generated. A decrease of the liquid-phase potential at the hydrogen-air interface would cause a potential of up to about 1.44 V in the corresponding cathode, as shown in Fig. 4. This high potential would cause corrosion of the carbon carrier in the catalyst layer and performance degradation.