Development of novel and metallic components for fuel cells with micro/nano technology

The performance, cost and durability of fuel cells are significantly impacted by the characteristics of the gas diffusion layer (GDL) whose principal functions are to efficiently transport the reactants and products to and from the membrane, as well as to conduct heat and electric current. Current GDL materials, which include carbon cloth or paper, have shown limited success, motivating the development of new materials. In addition to good thermal and electrical conductivity of the GDL, its pore size distribution must be optimized for improving the transport of both gas and liquid phases during fuel cell operation.

A novel metallic porous medium with improved thermal and electrical conductivities and controllable porosity was developed based on micro/nano technology for its potential application in PEM fuel cells. In this work to demonstrate its applicability, the gas diffusion medium, made of 12.5 μm thick copper foil, was tested in an operational fuel cell. The small thickness and straight-pore feature of this novel material provides improved water management even at low flow rates. The performance does not decline at lower flow rates, unlike conventional gas diffusion layers. It has been shown that the performance can be further enhanced by increasing the in-plane transport. The improvements of such gas diffusion layer, including pore shape, porosity, and surface properties, are fully discussed.

Zhang F.Y., Advani S.G., and Prasad A.K., "Performance of a metallic gas diffusion layer for PEM fuel cells," Journal of Power Sources, Vol. 176, pp. 293-298, January 21, 2008. doi:10.1016/j.jpowsour.2007.10.055
Zhang F.Y., Prasad A.K., and Advani S.G., "Investigation of a copper etching technique to fabricate metallic gas diffusion media," Journal of Micromechanics and Microengineering, Vol. 16, pp. N23-N27, November 1, 2006. doi:10.1088/0960-1317/16/11/N02
Zhang F.Y., Prasad A.K., Advani S.G., "Nano-based novel gas diffusion media," Patent no. US 7785748 (provisional application filed April 3, 2006, patent granted August 31, 2010).