Enhanced ionic conductivity in oxide heterostructures

Article By:

Garcia-Barriocanal, Javier Universidad Complutense, Madrid, Spain.

Rivera-Calzada, Alberto Universidad Complutense, Madrid, Spain.

Varela, Maria Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Sefrioui, Zouhair Universidad Complutense, Madrid, Spain.

Iborra, Enrique Escuela Técnica Superior de Ingenieros de Telecomunicación, Universidad Politécnica, Madrid, Spain.

Leon, Carlos Universidad Complutense, Madrid, Spain.

Pennycook, Stephen J. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Santamaria, Jacobo Universidad Complutense, Madrid, Spain.

Last reviewed:2010

DOI:https://doi.org/10.1036/1097-8542.YB100185

Fuel cells are electrochemical devices used to generate energy out of hydrogen. In a fuel cell, two conducting electrodes are separated by an electrolyte that is permeable to ions (either hydrogen or oxygen, depending on the fuel-cell category) but not to electrons. An electrode catalytic process yields the ionic species, which are transported through the electrolyte, while electrons blocked by the electrolyte pass through the external circuit. Polymeric membrane (PEMFC) or phosphoric acid fuel cells (PAFC) operating at low temperatures are the preferred option for transportation because of their quite large efficiencies (50%), compared with gasoline combustion engines (25%). Other uses are also being considered, such as battery replacements for personal electronics and stationary or portable emergency power. Solid-oxide fuel cells (SOFCs), operating at high temperatures, are a better option for stationary power generation because of their scalability. Here O²⁻ ions are the mobile species that travel at elevated temperatures (800–1000°C) through a solid electrolyte material to react with H⁺ ions in the anode to produce water (Fig. 1). The high operating temperatures of solid oxide fuel cells are a major impediment to their widespread use in power generation. Thus, reducing this operating temperature is currently a major materials research goal, involving the search for novel electrolytes as well as active catalysts for electrode kinetics (oxygen reduction and hydrogen oxidation).

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