Fabrication of Graphite/PTFE Based Electrodes for Proton Exchange Membrane Fuel Cell 2014-01-2433

Fuel cells are a promising energy source on account of their high efficiency and low emissions. Proton exchange membrane fuel cells (PEMFC) are clean and environmental-friendly power sources, which can become future energy solutions especially for transport vehicles. They exhibit good energy efficiency and high power density per volume. Working at low temperatures (<90°C), hydrogen fuelled proton exchange membrane fuel cells (PEMFCs) are identified as promising alternatives for powering autos, houses and electronics. At the middle of the proton exchange membrane (PEM) fuel cell is the membrane electrode assembly (MEA). The MEA consists of a proton exchange membrane, catalyst layers, and gas diffusion layers (GDL). However, most of the researchers have already mentioned that PEMFC are not competitive enough to rechargeable lithium ion battery with respect to price because of the rare metal used such as platinum in it. Presence of platinum in PEM fuel cells is one of the reasons why fuel cells are excluded from commercialization. Therefore, reducing the amount of platinum used in fuel cells is very important for their commercialization. The catalyst layer of a PEM fuel cell is a porous mixture of polymer, carbon, and platinum. The characteristics of the catalyst layer play a critical role in determining the performance of the PEM fuel cell. In this work, we develop modified Graphite/ polytetrafluoroethylene (PTFE) based electrodes for PEMFC. Graphite owing to its conductivity, corrosion resistance and easy machinability, is the preferred material in the system. For adherence of the graphite powder on the electrode we use N-methyl pyrollidone medium. Then PTFE dispersion are heated to 80°C and added with chemically treated graphite powder and this paste is coated on the electrode. Carbon-fluorine (C-F) bonding in Teflon (PTFE) is very strong as compared to the other organic bonds; therefore it is quite difficult to break. Also, smaller size of fluorine atom makes it difficult to exchange the electrons for the formation of multiple bonds. This property of PTFE is used to enhance the overall functionality of the fuel cell and hence decrease the amount of platinum catalyst used.