Effects of clamp load on PEFC performance and over voltages (comparison of performance between paper and cloth type GDLs)

The performance and over voltages of the polymer electrolyte fuel cell (PEFC) were evaluated using a test apparatus in which the clamp load of a test cell could be changed between 100 N and 1 000 N. The comparison of the performance between paper and cloth type gas diffusion layers (GDL) was also evaluated. The effect of GDL on the PEFC performance varies greatly depending on the clamp load and gas humidification condition. Under moderate humidification condition, an increase in the cell clamp load is effective in reducing IR over voltage, and thereby improving the PEFC performance significantly. However, the high clamp loads over 600 N contribute slightly to the improvement in the performance. The performance of the paper type GDL is higher than that of the cloth type GDL at high clamp loads. Under high humidification condition, however, the cloth type GDL shows lower concentration over voltage, resulting in the more excellent performance at a relatively low clamp load of 300 N, compared with the paper type GDL. However, when the clamp load becomes too high, because the ability to reduce concentration over voltage of the cloth type GDL is degraded, a significant difference in the performance between the paper and the cloth type GDLs can not be recognized.