Optimization of catalyst layer thickness for achieving high performance and low cost of high temperature proton exchange membrane fuel cell

The thickness of catalyst layer (CL) determines the electrochemical performance and the cost of high temperature proton exchange membrane fuel cell (HT-PEMFC). However, various values (e.g. 100 μm, 50 μm, 10 μm) of CL thickness are reported in the previous studies. To identify the optimal CL thickness to reduce the PEMFC cost without sacrificing the electrochemical performance, it is necessary to first identify the effective reaction thickness (ERT) of both anode and cathode. A numerical non-isothermal 3D model was developed considering the activation loss, concentration loss and ohmic loss at two electrodes, respectively. After model validation, parametric analyses were performed to investigate the effects of temperature, working voltage and flow rate on the performance of the fuel cell, especially on ERT. It is found that the ERT increases with increasing temperature. The working voltage and the cathode flow rate have opposite influences on the ERT of the two electrodes. The ERT highly depends on the ratio of activation loss and concentration loss (η_act+η_conc) to ohmic loss η_ohmic. Considering the utilization rate of the catalyst and cell performance, the appropriate CL thicknesses for anode and cathode electrode are 10–17 μm and 15–30 μm, respectively. This study clearly demonstrates that we can reduce the CL cost and maintain high fuel cell performance by carefully controlling the thickness of CL.