Improvement of the PEMFC performance at low humidity by tailoring structure of the catalyst layer

Abstract

A proton exchange membrane fuel cell (PEMFC) is one of the promising next-generation power suppliers. However, external humidification is required to preserve sufficient hydration in the PEMFC systems. Previously, a number of researchers have extensively studied the self-humidifying membrane or the catalyst layer (CL) to enhance the fuel-cell performance at low relative humidity (RH). Nevertheless, the key properties which impact the CL morphology and the addition of SiO2 particles are inadequately investigated. In this study, the CL morphology for the high fuel-cell performance at low RH operation is investigated with various aspects. The solvent effect on the CL morphology firstly was examined by using different solvents. Subsequently, the hygroscopic SiO2 particle was employed into the CL to increase its water uptake characteristics. Lastly, to enhance the cell polarization at low RH operation, the SiO2-containing CLs were prepared by different solvents. As a result, it is demonstrated that the agglomerate structures significantly affects the fuel-cell performance at low RH operation. Because of the break-in of the SiO2 particle into the agglomerate, the enhanced cell polarization was obtained at low RH operation owing to improved resistance and triple-phase boundary. Consequently, it is important to improve the Pt/C-SiO2-Nafion agglomerate structure for enhancing the fuel-cell performance under low RH operation.