MOSCOW, October 20. /TASS/. Researchers from the Skolkovo Institute of Science and Technology (Skoltech) and Yerevan State University (Armenia) figured out the surface structure of ruthenium dioxide, Skoltech’s press-office reported. This material is applied in supercapacitors (supercaps) which have a capacity that dramatically exceeds the capacity of conventional capacitors. The new study explains the appearance of pseudo-capacity on such cathodes. The study’s results have been recently published in the prominent journal Scientific Reports.

By comparing model data on low surface reconstruction energy of ruthenium dioxide RuO2, its electrochemical properties, and data on modeling images from scanning tunnel microscopy (STM), the scientists were able to find out the reason for the appearance of this pseudo-capacity.

A supercapacitor or supercap is an electrochemical device which can accumulate energy and in the future might replace conventional batteries. The most widely used material to construct cathodes for supercaps is ruthenium dioxide RuO2. The properties of supercapacitors depend on the processes of the surface of ruthenium dioxide crystals. For example, it is unclear what the reasons are for this pseudo-capacity, which manifests itself as charges accumulating on the electrode surface in supercapacitors.

Usually, the surface of materials is examinated using microscopes, but this sort of approach is capable of showing only the upper layer without going into the depth of the material. To explore the subject, researchers from Skoltech and Yerevan employed computer modeling to predict the structure of ruthenium dioxide’s deeper layers of the surface.

Research into the appearance of pseudo-capacity on the surface was conducted by modeling the process of inclusion of hydrogen atoms into the reconstructed surface. According to the results of the study, the pseudo-capacity is caused by the special atomic structure of RuO2 surface where redox reactions take place. This finding will make it possible for us to better understand the principles of how supercaps function, which in turn will lead to the design of new-age devices with greater capacity.