Nickel anodes early developments

Anode Unalloyed porous nickel anodes used by early developers were found to shrink during operation under the stack compressive load, resulting in undesired dimensional change, reduced surface area, and lower electrochemical performance. Alloying with chromium and/or aluminum provides oxide dispersion strengthening, resulting in adequate creep strength. Excellent mechanical and chemical stability of the baseline Ni-Al anode is verified in an 18,000 h field operation. Fig. 8 shows that the structure of the... 

A very early use of anodic alumina as a template involved colonization of the alumina by depositing nanometals in the pores [39]. Somewhat later, Kawai and Ueda templated cobalt and nickel in alumina by electrodeposition [40]. Other metals were deposited by Andersson et al. [41] and Patel et al. [42]. The use of anodic alumina as a template increased after Furneaux et al. developed a convenient voltage-reduction method for detaching the porous anodized alumina from the underlying aluminum [38]. 

Although a wide range of materials has been considered as anode materials for SOFC (14), most developers today use a cermet of nickel and YSZ. Early on in the development of SOFC, precious metals such as platinum and gold were used, as well as pure transition metals such as nickel and iron. Because of the physical and chemical instability of these materials, other materials such as nickel aluminide were tested. 

As membrane material for their direct ammonia-oxygen fuel cells, Lan and Tao used a blend of the anion-exchange resin Amberlite IRA 400 (hydroxide form) and poly(vinyl alcohol). As cathode material, Mn02 deposited on carbon materials was used. In different cell versions the anodes were prepared from Pt-Ru-C and from chrom-decorated nanosized nickel (size about 6 nm). Experiments with such cells at room temperature showed maximal power densities in the range 12 to 16 mW/cm. In some cases the power densities for ammonia-fed cells were higher than those for hydrogen-fed cells. The authors note that the development of direct ammonia fuel cells with alkaline membranes and inexpensive catalysts is still at an early stage. 

The early magnesium alloys suffered rapid attack under moist conditions, mainly because of the presence of impurities, notably iron, nickel, and copper. These impurities or their compounds act as minute cathodes in the presence of a corroding medium and create micro-cells with the anodic magnesium matrix (Polmear, 1989). High-purity alloys are a relatively recent development. In high-purity alloys the concentrations of these impurities are controlled to below critical concentrations and as a consequence high-purity alloys are markedly more resistant to salt water than are alloys of normal purity (Shreir, 1965). 

The focal point of work on solid oxide fuel cells during this period was the development of electrode materials. An early problem was poor adhesion of the anode layers, which became obvious in 1963 [59]. Spacil as early as 1964 found the now well-known solution of using layers of nickel closely mixed with solid electrolyte material [101]. 

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