Direct alcohol fuel cells technology

Abstract The faster kinetics of the alcohol oxidation reaction in alkaline direct alcohol fuel cells (ADAFCs), opening up the possibility of using less expensive metal catalysts, as silver, nickel, and palladium, makes the alkaline direct alcohol fuel cell a potentially low-cost technology compared to acid direct alcohol fuel cell technology, which employs platinum catalysts. In this work an overview of catalysts for ADAFCs, and of testing of ADAFCs, fuelled with methanol, ethanol, and ethylene glycol, formed by these materials, is presented. 

The faster kinetics of alcohol oxidation and oxygen reduction reactions in alkaline direct alcohol fuel cells opens up the possibility of using less expensive Pt-free catalysts, as nickel, gold, palladium and their alloys [30]. Thus, the cost of ADAFC could be potentially lower compared to the acid DAFC technology if non-precious metal alloys are used for the alcohol electrooxidation, being the nanoparticulated Ni-Fe-Co alloys developed by Acta (Italy) with the trade name of HYPERMEC a good example. 

In the first chapter, we introduce the concept of methanol economy, as an alternative to the most popular but still elusive hydrogen economy, and we also provide a brief historical description of fundamental research on electrochemical oxidation of methanol and the development of the first alkaline direct methanol fuel cells more than 60 years ago. The operating principles of PEM and alkaline direct alcohol fuel cells are analyzed, as well as their components, configuration, and operation modes, with a final remark on the state of the art of the technology. 

K.W. Feindel, Magnetic resonance imaging (MRI) techniques for polymer electrolyte membrane and direct alcohol fuel ceU characterization, in C. Hattnig, C. Roth (Eds.), Polymer Electrolyte Membrane and Direct Methanol Fuel Cell Technology, In Sim Characterization Techniques for Low Temperature Fuel Cells, vol. 2, Woodhead Publishing Limited, Cambridge, UK, 2012. 

C. Lamy and E. M. Belgsir, Other Direct-Alcohol Fuel Cells, in Handbook of Fuel Cells—Fundamentals, Technology and Applications, Vol. 1, W. Vielstich, A. Lamm, and H. A. Gasteiger, Eds., Wiley, 2003, pp. 323-334. 

Most of issues related to future development of PEM technology as discussed in the previous section is applicable to direct alcohol fuel cell (DAFC). Few pertinent points peculiar to DAFC are mentioned below. 

Application of an acid-alkaline concept to direct alcohol fuel cells has also been reporfed. Cheng and Chan [29] reported operation of a 6-cell slack of dual pH elecfrolyte fuel cell using ethanol fuel. A BPM MB-3 supplied by Membrane Technology Centre (Russia) was used. Each anode chamber contained 4 mL 7 mol L NaOH and 0.5 mol ethanol. Each cathode chamber... 

The direct methanol fuel cell is a special form of low-temperature fuel cells based on PEM technology. In the DMFC, methanol is directly fed into the fuel cell without the intermediate step of reforming the alcohol into hydrogen. Methanol is an attractive fuel option because it can be produced from natural gas or renewable biomass resources. It has the advantage of a high specific energy density, since it is liquid at operation conditions. The DMFC can be operated with liquid or gaseous methanoFwater mixtures. 

Direct ethanol fuel cells (DEFCs) produce power directly from ethanol without prior reforming. Compared with methanol used as the fuel for DMFCs, ethanol is nontoxic, environmentally friendly, and universally available, and making the handling easy. Since ethanol is also a liquid alcohol like methanol, the technological issues of crossover, discharge of carbon dioxide, and passive operation are comparable. 

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