Novel Method to Boost Capacity of Energy Sources for Portable Electronics

Researchers from Skolkovo Institute of Science and Technology (Skoltech), Moscow State University (MSU), and Moscow Institute of Physics and Technology (MIPT) have suggested a new method to substituting carbon atoms with nitrogen atoms in the supercapacitor’s crystal lattice and created a novel capacity enhancement technique based on carbon lattice alteration with the help of plasma. Their findings can aid in the development of the next generation of power sources for portable electronics. The results from the study were reported in Nature – Scientific Reports.

As portable devices progress, the demand for new kinds of energy sources also increases. Researchers are constantly hunting for an operative way to enhance the performances of electrochemical energy sources. A chemical source of current, the supercapacitor is identified by high charge and discharge rates and a higher energy storage capacity per unit volume or mass as compared to a battery. It is routine to use porous materials, such as porous metals or carbon, for supercapacitors, although metals make the source a lot heavier. There are a number of ways of increasing the capacity of electrochemical energy sources while maintaining their weight unaffected, for instance, by using other lighter elements or adding the atoms of another element into the crystal lattice (doping.) The second technique is said to deliver better prospects, as it enables easy atom addition at the carbon structure synthesis stage. Nitrogen is one of the elements chosen for doping. Nitrogen is a part of redox reactions, which results in an extra increase in capacity. Although researchers have known about the doping technique, the effect of nitrogen on the electrochemical features is still not properly understood.

A group of researchers led by Skoltech Senior Researcher, Dr. Stanislav Evlashin, showed a simple approach of boosting the supercapacitors’ electrochemical performance. Their method offers a better understanding of the nitrogen incorporation process. The scientists carried out the experiments using Carbon Nanowalls composed of vertically oriented graphene sheets, wherein they substituted some of the carbon with nitrogen using carbon structure treatment by plasma. The results of the study are a crucial step towards forming new energy sources.

In this study, we used a plasma post-treatment approach in order to improve the capacity of the electrodes. We used carbon structures with a high specific surface area as a material for doping in the nitrogen plasma and replaced a part of carbon atoms with nitrogen atoms to enhance the electrochemical capacity of the energy source. This approach can be applied to modify any carbon structure. The obtained samples were tested using various methods. The experimental results displayed a six-fold increase in electrochemical capacity and excellent cycling stability. We also performed DFT simulation of the nitrogen incorporation process that sheds some light on the complex incorporation mechanisms.

Dr. Stanislav Evlashin, Senior Researcher, Skoltech