Direct methanol fuel cells advantages

The dynamic behavior of fuel cells is of importance to insure the stable operation of the fuel cells under various operating conditions. Among a few different fuel cell types, the direct methanol fuel cell (DMFC) has been known to have advantages especially for portable... 

Wang Y, Li L, Hu L, Zhuang L, Lu J, Xu B. 2003. A feasibility analysis for alkaline membrane direct methanol fuel cell Thermodynamic disadvantages versus kinetic advantages. Electrochem Commun 5 662. 

Despite the uncertainty regarding the exact nature of the active site for oxygen reduction, researchers have managed to produce catalysts based on heat-treated macrocycles with comparable activities to state-of-the-art platinum catalysts. In numerous cases researchers have shown activity close to or better than platinum catalysts.64,71,73,103,109 Since the active site for the ORR in these materials is not fully understood, there is still potential for breakthrough in their development. Another advantage of this class of materials that should be mentioned is their inactivity for methanol oxidation, which makes them better suited than platinum for use in direct methanol fuel cell cathodes where methanol crossover to the cathode can occur.68,102,104,122-124 While the long-term activity of heat treated materials is... 

This survey focuses on recent developments in catalysts for phosphoric acid fuel cells (PAFC), proton-exchange membrane fuel cells (PEMFC), and the direct methanol fuel cell (DMFC). In PAFC, operating at 160-220°C, orthophosphoric acid is used as the electrolyte, the anode catalyst is Pt and the cathode can be a bimetallic system like Pt/Cr/Co. For this purpose, a bimetallic colloidal precursor of the composition Pt50Co30Cr20 (size 3.8 nm) was prepared by the co-reduction of the corresponding metal salts [184-186], From XRD analysis, the bimetallic particles were found alloyed in an ordered fct-structure. The elecbocatalytic performance in a standard half-cell was compared with an industrial standard catalyst (bimetallic crystallites of 5.7 nm size) manufactured by co-precipitation and subsequent annealing to 900°C. The advantage of the bimetallic colloid catalysts lies in its improved durability, which is essential for PAFC applicabons. After 22 h it was found that the potential had decayed by less than 10 mV [187],... 

Fuel cells o fer important advantages as a power source, such as the potential for high efficiency, clean exhaust gases and quiet operation. In addition, the direct methanol fuel cell offers special benefits as a power source for transportation, such as potential high energy density, no need for a fuel reformer and a quick response. These advantages, however, have not been fully realized yet. One of the problems is the poor performance of the fiiel electrode. Even platimun, which seems the most active single element for methanol oxidation in add media, loses its electrocatalytic activity rapidly by the accumulation of adsorbed partially oxidized products. 

The storage, transportation, and handling of H2 are difficult. It has been reported that between H2 production and H2 application, a 15% loss due to leakage is unavoidable. Liquid methanol has advantages over H2 in this respect, and direct methanol fuel cells are presently believed to be the ideal energy converting alternatives to hydrogen PEMFCs. 

Fuel cells offer the possibility of reduced emissions and high efficiency for transportation applications. Of the various fuel cells being considered, the direct methanol fuel cell (DMFC) is very attractive due to the key advantages of reducing system complexity and potentially improving transient response compared to reformate-air fuel cell systems. However, DMFCs currently require unsupported noble metal catalysts at high loadings of... 

The held to which the specific features of CNTs and CNFs could bring the most significant advancements is perhaps that of fuel cell electrocatalysis [125,187]. The main uses of CNTs or CNFs as catalyst support for anode or cathode catalysis in direct methanol fuel cells (DMFCs) or proton-exchange membrane fuel cells (PEMFCs) are covered in Chapter 12. In this section we summarize the main advantages linked to the use of nanotubes or nauofibers for these applications. 

Intense international academic and industrial research efforts have recently placed the direct methanol fuel cell (DMFC) on the brink of commercialization [xi,xii]. The major advantage of the DMFC relative to other fuel cells is the simplicity of... 

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. 

The fuel cell has a proven history with solid oxide based systems. Recent needs for miniaturization have generated new ideas of fuel sources and structures. These include direct methanol fuel cells (DMFCs) and polymer electrolyte membrane fuel cells (PEMFCs). These fuel cells have advantages over others for several reasons. A key quality is the potential energy that the fuel sources provide with respect to the fuel costs. 

Sulfonated PPESK membrane materials have been demonstrated to be useful for various types of fuel cells, such as formic acid fuel cells, and methanol fuel cells. The direct methanol fuel cell has certain advantages over the proton exchange membrane fuel cell because it is more suitable for portable applications. Because of the interest in these cells, many papers focus on materials suitable for membranes. The reactions in a direct methanol fuel cell are ... 

The first of these possibilities has the advantage of keeping the fuel cell at a higher temperature and thus realizing a better electrical performance. Shukla et al. (1995) have described such a direct methanol fuel cell. A temperature of 200 C was maintained in an evaporator for a 2.5 M aqueous methanol solution. The fuel cell s working temperature was lower. At a temperature of 100°C current density of 200 mA/cm could be realized at a voltage of about 0.5 V (the total platinum content of both electrodes was 5 mg/cm ). 

For very small loads (<200 W) also direct methanol fuel cells (DMFC) can be used, which are aheady being produced in large quantities (especially for the leisure market and the mobile sector). Another advantage of these FC type is their fuel Methanol is available in special cartridges, which can be ccmnected— unlike compressed gas cylinders—without specific user skills. 

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