Direct methanol fuel cells, principles

The purpose of the present review is to summarize the current status of fundamental models for fuel cell engineering and indicate where this burgeoning field is heading. By choice, this review is limited to hydrogen/air polymer electrolyte fuel cells (PEFCs), direct methanol fuel cells (DMFCs), and solid oxide fuel cells (SOFCs). Also, the review does not include microscopic, first-principle modeling of fuel cell materials, such as proton conducting membranes and catalyst surfaces. For good overviews of the latter fields, the reader can turn to Kreuer, Paddison, and Koper, for example. 

Fig. 3.1 Illustration of a micro-direct methanol fuel cell (a) top view of a planer cell and (b) cross-sectional view with working principle...

Fig. 5.1 Concept and principle of the DMFC fabricated by Si MEMS. [4] Reprinted from Proc. of Transducers 05, Houjou H, Motokawa S, Ishizuka M, Mizuno J, Momma T, Osaka T, Shoji S. Metallization on 3-D microstructures using spray coating for high performance micro direct methanol fuel cell (pDMFC), 1437, 2005, with permission from IEEE...

Figure 6.44 Principle of a direct methanol fuel cell (DMFC).

At present, most of the work toward building methanol fuel cells relies on technical and design principles, developed previously for polymer electrolyte membrane fuel cells. In both kinds of fuel cells, it is common to use platinum-ruthenium catalysts at the anode and a catalyst of pure platinum at the cathode. In the direct methanol fuel cells, the membrane commonly used is of the same type as in the hydrogen-oxygen fuel cells. The basic differences between these versions are discussed in Section 19.7. 

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. 

Zhao TS (2009) Micro fuel cells principles and applications. Elsevier, Amsterdam Zhou Y, Wang X, Wu Z, Wu X, Liu L (2011) Passive fuel delivery based on hydrophobic porous silicon for micro direct methanol fuel cells. In TREE 24th international conference on micro electro mechanical systems (MEMS), Cancun, Mexico Zhu L, Lin KY, Morgan RD, Swaminathan VV, Kim HS, Gurau B, Kim D, Bae B, Masel RI, Shannon MA (2008) Integrated micro-power source based on a micro-silicon fuel cell and a micro electromechanical system hydrogen generator. J Power Sources 185 1305-1310... 

Direct methanol fuel cell is an electrochemical device that converts the chemical energy of a reaction directly into electrical energy. The principle and schematic diagram of a DMFC is shown in Figure 9.1. In a typical DMFC, methanol and water molecules are simultaneously electro-oxidized at anode to produce CO2, electrons, and protons through the reaction (methanol oxidation reaction, MOR) ... 

Basic Principles of Direct Methanol Fuel Cell Operation... 

Direct methanol fuel cells are a class of polymer electrolyte membrane (PEM) fuel cells that typically employ a cation exchange membrane to separate the anode and cathode compartments. To illustrate the basic principles of DMFC operations, we shall take a typical, liquid-feed cell with a cation exchange membrane (alkaline exchange membranes are an alternative, and these are discussed later in this chapter). This is depicted in Figure 5.1. 

In principle biomass is a useful fuel for fuel cells many of the technologies discussed above for using biomass as a fuel produce either methane or hydrogen directly and as highlighted below synthesis gas production from biomass for conversion to methanol is an attractive option. Cellulose-based material may be converted to a mixture of hydrogen (70% hydrogen content recovered), CO2 and methane by high-temperature treatment with a nickel catalyst. 

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