INSIGHT INTO Fuel Cells

The fuel cell-powered scooter project has provided valuable insights into fuel cell operation under real-world conditions as well as monitoring and control strategies to maximize power and efficiency. The electronics developed for the project have found dual use with other fuel cell testing systems. Additionally, the fuel cell-powered scooter has proven valuable as a way to illustrate and demystify fuel cell systems, and as a public relations tool to promote alternative energy research at Los Alamos National Laboratory. 

Synchrotron X-ray tomography can provide highly resolved, 3D insights into fuel cells. In contrast to neutron measurements, the brilliance of the synchrotron... 

As discussed previously, a number of different materials have been considered as potential candidates to be used as diffusion layers in PEMFCs and direct liquid fuel cells (DLFCs). The two materials used the most so far in fuel cell research and products are carbon fiber papers and carbon cloths, also known as carbon woven fabrics. Both materials are made from carbon fibers. Although these materials have been quite popular for fuel cells, they have a number of drawbacks—particularly with respect to their design and model complexity—that have led to the study of other possible materials. The following sections discuss in detail the main materials that have been used as diffusion layers, providing an insight into how these materials are fabricated and how they affect fuel cell performance. 

The previous discussion asserts that design, fabrication, and implementation of stable and inexpensive materials for membranes and catalyst layers are the most important technological challenges for PEFC developers. A profound insight based on theory and modeling of the pertinent materials will advise us how fuel cell components with optimal specifications can be made and how they can be integrated into operating cells. 

This new technique incorporates a catalyzed short contact time (SCT) substrate into a shock tube. Fig. 13. These SCT reactors are currently used in industry for a variety of applications, including fuel cell reformers and chemical synthesis.The combination of a single pulse shock tube with the short contact time reactor enables the study of complex heterogeneous reactions over a catalyst for very well defined regimes in the absence of transport effects. These conditions initiate reaction in a real environment then abruptly terminate or freeze the reaction sequence. This enables detection of intermediate chemical species that give insight into the reaction mechanism occurring in the presence of the chosen catalyst. There is no limitation in terms of the catalyst formulations the technique can study. 

The ultimate goal of any diagnostic technique is to improve the design of PEM fuel cells to achieve the desired performance, durability, reliability, and cost. Thus far most species distribution research has focused on technique development and verification. A summary of the previously presented techniques is shown in Table 1. However, as the techniques continue to mature, they are providing increasing insight into improved fuel cell designs. 

As shown in this review, test equipment integrated with several diagnostic techniques is preferred for a deeper insight into the mechanisms that cause performance losses and spatial non-uniform distribution. As a consequence, more information, which is simultaneously obtained with these diagnostic tools, will strongly support development of empirical models or validate theoretical models predicting performance as a function of operating conditions and fuel cell characteristic properties. 

Advances in fuel cells were later accelerated by space and defense programs. Fuel cells found initial practical application with the Gemini (1962-1966) and the Apollo (1968-1972) spacecraft missions, and are still used to provide water and electricity for the Space Shuttle. The upgrade in fuel cell performance over the last four decades has been based on the development of new proton-conducting polymers, like Nafion and Gore-tex , ceramics and catalysts, as well as on greater insights into... 

For a long time, solid-state methods have been successfully used to study molecular dynamics in material science applications, ranging from the investigation of chain order in elastomers (see, for example. Ref. for a recent application) to the investigation of the mechanism of proton conduction in fuel cell polymer electrolyte membranes. While solution-state NMR techniques have provided unprecedented insight into the... 

The electrochemical oxidation of methanol has been extensively studied on pc platinum [33,34] and platinum single crystal surfaces [35,36] in acid media at room temperature. Methanol electrooxidation occurs either as a direct six-electron pathway to carbon dioxide or by several adsorption steps, some of them leading to poisoning species prior to the formation of carbon dioxide as the final product. The most convincing evidence of carbon monoxide as a catalytic poison arises from in situ IR fast Fourier spectroscopy. An understanding of methanol adsorption and oxidation processes on modified platinum electrodes can lead to a deeper insight into the relation between the surface structure and reactivity in electrocatalysis. It is well known that the main impediment in the operation of a methanol fuel cell is the fast depolarization of the anode in the presence of traces of adsorbed carbon monoxide. 

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