The photo is sourced from arstechnica.com
Fuel cells transform the chemical energy of fuel into electricity. Technically, this occurs via the interaction of a fuel gas and an oxidant gas through a solid electrolyte (a substance conducting an electric current through ionic dissociation). The most promising fuel cells are hydrogen-air ones, whose functioning involves hydrogen (fuel) interacting with atmospheric oxygen (oxidant), producing water. For the reaction to be successful, the role of the electrolyte should be performed by a material with a high anion (oxygen-ionic) conductance and none other. The materials meeting this condition include perovskite (calcium titanate, which is found in igneous rocks in its natural form) and zirconium dioxide (a strong material used in dentistry) stabilised with yttrium oxide (colourless crystals, which do not dissolve in water).
Using supercomputer modeling, the project participants have identified a new substance: the aforementioned magnocolumbite (MgNb2O6), which has oxygen-ionic conductance but no electronic or cation (electronic-ionic) conductance. “As a rule, crystals can have either electronic or mixed (electronic-ionic) conductance,” Artem Kabanov, candidate of physical and mathematical sciences, senior researcher at Samara Polytech, is quoted as saying by Rossiyskaya Gazeta. “The compound we have discovered has only anion, or oxygen, conductance because oxygen serves as an anion here. Only several dozens of substances with the same characteristic are known to science.”
The authors of the study suggest that anion conductance is caused by the defects in the crystal lattice of the magnocolumbite, as a result of which mobile ions jump to the nearest free positions, vacating their own positions in the course of the hydrogen-oxygen reaction.
“Reactions in the fuel cell can only occur at a high temperature, which is why the electrolyte must be resistant to high temperatures. In that regard, the magnocolumbite has proven to be as good as perovskites or zirconium and yttrium-based compounds. Moreover, the magnocolumbite is resistant to the aggressive medium of the fuel cell and has the suitable linear expansion coefficient,” Artem Kabanov concludes (as per RIA Novosti). Thanks to these properties, the new material can be used in not only fuel cells but also in gas sensors/ analysers.
