Fuel, Vol.91, No.1, 192-199, 2012
Cathode catalyst layer design for proton exchange membrane fuel cells
To improve water management and enhance the catalyst utilization of the cathode catalyst layer of proton exchange membrane (PEM) fuel cells, the effects of polytetrafluoroethylene (PTFE) addition in the catalyst ink and the loading pattern of the catalyst layer were investigated. Two types of catalyst ink were used: a typical one without PTFE (Pt on carbon support + Nafion) and another type added with PTFE (Pt on carbon support + Nafion + PTFE). In exploring the effect of PTFE addition into the conventional full loading pattern of catalyst layer, the presence of 10% PTFE in the catalyst layer improved the cell performance (34% increase of maximum power density) and the optimum Pt loading for the PTFE-added catalyst layer was 0.25 mg/cm(2). Two catalyst layer loading patterns created in this work were the strip and chess patterns. Each pattern consists of equal areas of several hydrophilic and hydrophobic segments. The hydrophilic segments were formed by using the ink with PTFE while the hydrophilic had no PTFE. For the catalyst loading pattern effect, the cell achieved the highest performance with the chess pattern, followed by the strip and full loading pattern for the case of 0.5 mg/cm(2) Pt loading having a thick catalyst layer of 50-mu m thickness. On the other hand, for the case of 0.25 mg/cm(2) Pt loading forming a thin catalyst layer of similar to 30-mu m thickness, the catalyst loading pattern had no effect on the cell's performance. (C) 2011 Elsevier Ltd. All rights reserved.
Keywords:Catalyst loading pattern;PEM fuel cell;Hydrophobic catalyst ink;Hydrophilic catalyst ink;Water management