Metal/air ‘fuel cells

The above described principle of the zinc/air battery is not limited to zinc as negative electrode material. Under the name metal/air fuel cell the aluminum/air battery is claimed as a superior solution with an output of 320 to 400 Wh/kg (75). This means a considerable increase compared to the rechargeable zinc/air system (Line 3b in Table 1.11). 

Keywords conducting polymers, oxygen reduction, composites, air-metal battery, fuel cells... 

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... 

We will demonstrate the preparation techniques for ASPEM and the characterization results. The relationship between structure and properties will be discussed and compared. The double-layer carbon air cathodes were also prepared for solid-state alkaline metal fuel cell fabrication. The alkaline solid state electrochemical systems, such as Ni-MH, Zn-air fuel cells. 

In Chapter 10, the authors will demonstrate the preparation techniques for ASPEM and the characterization results. The relationship between structure and properties will be discussed and compared. The double-layer carbon air cathodes were also prepared for solid-state alkaline metal fuel cell fabrication. The alkaline solid state electrochemical systems, sueh as Ni-MH, Zn-air fuel cells, Al-air fuel cells, Zn-Mn02 and Al-Mn02 cells, were assembled with anodes, cathodes and alkaline solid polymer electrolyte membranes. The electrochemical cells showed excellent cell power density and high electrode utilization. Therefore, these PVA-based solid polymer electrolyte membranes have great advantages in the applications for all-solid-state alkaline fuel cells. Some other potential applieations include small electrochemical devices, sueh as supercapacitors and 3C electronic products. 

Its performance was evaluated in hydrogen-oxygen and hydrogen-air fuel cells at ambient temperature in 6 N KOH and 5 N H SO. In both cases it was shown that water was efficiently retained in the electrolytic solutions and did not leak into the gas fuel feed stream. It was established that gas-diffusion electrodes based on back-side metallized porous membranes (Cao and Stetter 1991 Cao et al. 1992 Chang et al. 1993) are not affected by evaporation of water because the porous electrode is directly in contact with the bulk of the electrolyte solution. The mass transfer of analyte from the... 

Owing to highly corrosive acid conditions, stable catalysts and supports are required for the development of anodes working in direct methanol-air fuel cells. Platinum is the only stable catalyst material that shows a significant amount of activity for methanol oxidation. However, platinum has to be modified with other metals, such as ruthenium and tin, to obtain lower oxidation potentials. So, platinum and tin or ruthenium particles have been electrochemically immobilized in poly(3-methylthiophene) [142] and polyaniline [137] films, respectively. Compared to electrodes modified with platinum alone, the electrocatalytic properties... 

Metal fuel cells (MFCs) can provide the electrical power in a reliable and cost-effective manner. Preliminary studies undertaken by the author indicate that Zn-air fuel cells can yield electrical energy in excess of 4 kWh/kg, which are roughly 1,000 times the energy available from the Pb-acid batteries and three times the energy provided by the gasoline. 

Two new technologies have reduced the cost of alkali fuel cells to the point where a European company markets taxis that use them. One is the use of CO2 scrubbers to purify the air supply, making it possible to use atmospheric O2 rather than purified oxygen. The other is the development of ultrathin films of platinum so that a tiny mass of this expensive metal can provide the catalytic surface area needed for efficient fuel-cell operation. 

Recent testing in phosphoric acid fuel cells has shown improved performance using promoted Ft on carbon catalysts in the air cathode. The promoters are oxides of the base transition metals, e.g., Ti (O,... 

---