Highly flat and highly homogeneous carbon paper with ultra-thin thickness for high-performance proton exchange membrane fuel cell (PEMFC)

Abstract

Gas diffusion layer is one of the most important components of fuel cell, which supports the catalytic layer, collects the current and facilitates mass transfer. However, current carbon paper is mainly composed of long carbon fibers (CF), which brings drawbacks including rough surface, poor body homogeneity, excessive thickness, and preparation difficulty, etc. In this research, we invent a combination method to produce a highly flat, highly homogeneous, ultra-thin and high-performance carbon paper for proton exchange membrane fuel cell (PEMFC). The method combines the advantages of two materials, i.e. few-walled carbon nanotube (FWCNT) with high flatness and short CF with high porosity. And the combination method only contains three steps, material dispersion, carbon paper formation and heat treatment. The highest temperature for the heat treatment process is only 350 °C, which is much lower than the traditional 2000 °C. Due to the small size and fine distribution of FWCNT and CF, the new carbon paper exhibits highly flat (<6.4 μm in average), highly homogeneous (<3.6 μm in average), ultra-thin (<60 μm) properties, and high-performance in PEMFC. Therefore, this work shows that the optimized combination of several materials with outstanding properties could be used to prepare high performance carbon paper for PEMFC. • Preparation method of ultra-thin, highly flat and highly uniform carbon paper. • Contribution of FWCNT and short CF to thin, flat and uniform carbon paper surface. • Ohmic impedance and charge mass transfer impedance are the main factors. • Critical area in MEA are the two interfaces among the CL, GDL, and Nafion membrane.