| It was not until the latter half of the 20th century, with the technological developments associated with the space race, that the technical feasibility of the fuel cell was demonstrated. Various fuel cell technologies have emerged in this time period of which Proton Exchange Membrane Fuel Cells (PEMFCs) are of particular interest due to their lower operating temperatures, as compared with other types of fuel cells. Thus, they are ideal for applications such as small portable electronics and transportation. However, there are several challenges facing PEMFCs such as the development of efficient and durable proton exchange membranes (PEMs).;There are several techniques for the characterization of PEMs, One of these techniques is nuclear magnetic resonance (NMR), which has been an important tool in the characterization of ionic motion in liquids and solids. The ionic self-diffusion coefficient is of great importance in understanding the ionic conduction mechanism of electrolytic materials for fuel cells. In hydrated fuel cell membranes, the diffusion coefficient of water molecules also plays a vital role in ionic (protonic) transport. The measurements of the diffusion coefficients are performed by standard NMR methods. These measurements are usually performed as a function of temperature to obtain vital parameters such as activation energies. If an independent thermodynamic parameter such as pressure is employed, additional information about the ion transport process, such as activation volume, may be obtained. Studies of several types of fuel cell membranes based on sulfonated flouoropolymers are presented. |
