Alkaline fuel cells advantages

A significant cost advantage of alkaline fuel cells is that both anode and cathode reactions can be effectively catalyzed with nonprecious, relatively inexpensive metals. To date, most low cost catalyst development work has been directed towards Raney nickel powders for anodes and silver-based powders for cathodes. The essential characteristics of the catalyst structure are high electronic conductivity and stability (mechanical, chemical, and electrochemical). 

The removal of the C02 is entirely possible. European work has stressed the advantages of the alkaline fuel cell (e.g., it starts from the cold) more than U.S. work has. 

Alkaline fuel cells (AFC) — The first practical -+fuel cell (FC) was introduced by -> Bacon [i]. This was an alkaline fuel cell using a nickel anode, a nickel oxide cathode, and an alkaline aqueous electrolyte solution. The alkaline fuel cell (AFC) is classified among the low-temperature FCs. As such, it is advantageous over the protonic fuel cells, namely the -> polymer-electrolyte-membrane fuel cells (PEM) and the - phosphoric acid fuel cells, which require a large amount of platinum, making them too expensive. The fast oxygen reduction kinetics and the non-platinum cathode catalyst make the alkaline cell attractive. 

Several types of fuel cells have been developed and are classified according to the electrolytes used alkaline fuel cells, molten carbonate fuel cells, phosphoric acid fuel cells (PAFCs), PEMFCs, and solid oxide fuel cells (SOFCs). As shown in Figure 1.3, the optimum operation temperatures of these fuel cells are different, and each type has different advantages and disadvantages. 

This low-temperature fuel cell uses H2 and O2 reactants and a highly alkaline aqueous KOH electrolyte. The advantages of this fuel cell are the faster oxygen reduction reaction in the alkaline electrolyte and the possibility of using low-cost, nonprecious metal electrode catalysts, such as Ag-loaded carbon powder. The greatest problem with alkaline fuel cells is that the electrolyte reacts with traces of CO2 to produce insoluble carbonates. 

Alkaline fuel cells have numerous advantages over proton exchange membrane fuel cells on both cathode kinetics and ohmic polarization [115]. 

Alkaline fuel cells present several potential advantages over their acidic counterparts, dominating low-temperature fuel cell appUcatimis today. Main advantages include performance improvements and cost reduction, both associated with the use of NPMCs. 

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 applications include small electrochemical devices, such as supercapacitors and 3C electronic products. 

Lan and Tao [22] successfully applied a novel fuel cell type with an alkaline membrane to oxidize ammonia at room temperature. Compared to solid oxide fuel cells, the alkaline membrane fuel cell is less brittle and can be operated at low temperatures. As an advantage of alkaline membrane fuel cells over conventional alkaline fuel cells, no KOH-based electrolyte is needed. The researchers used two types of anodes first platinum and ruthenium deposited on carbon and sec-raid chromium-decorated nickel. The ammraiia sources were either ammraiia gas or a 35 wt% aqueous ammonia solution. 

V. Hacker, P. Enzinger, M. Muhr, K. Kordesh, J. Gsellman, M. Cifrain, P. Prenninger, K. Meitz, R. Aronsson, Advantages of Alkaline Fuel Cell Systems for Mobile Applications, 2000 Fuel Cell Seminar Program and Abstracts, Portland, OR sponsored by the Fuel Cell Seminar Organizing Committee, October 30 - November 2, 2000. 

Francis Bacon first developed the AFC during the 1930s. The AFC offers the advantage of faster cathode reaction rates and, therefore, higher energy efficiency, and the ability to use a wide range of cathode catalysts compared to the acidic electrolyte in PEM fuel cells [12]. The electrochemical reactions in an alkaline fuel cell can be expressed by equation (1.10) through equation (1.12). 

Alkaline fuel cells (AFCs) have been used by NASA on space missions and can achieve power-generating efficiencies of up to 70 % [13, 69-72]. The operating temperature of these cells range between room temperature to 250 °C. The electrolyte is aqueous solution of alkaline potassium hydroxide (30-75 w %) soaked in a matrix [13]. (This is advantageous because the cathode reaction is faster in the alkaline electrolyte, which means higher performance). 

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