MOSCOW, 31 Aug. OmSTU scientists together with colleagues from the Oncology Center of the Siberian Branch of the Russian Academy of Sciences have improved the material for energy storage devices. According to them, the proposed composite based on carbon nanotubes can accumulate five times more charge than the standard used. The results of the study were published in the journal Solid State Physics.
Supercapacitors (or ionistors) are a fairly new and promising type of energy storage devices. Their specific capacity (the amount of accumulated charge per unit mass) is 100 thousand times or more higher than the capacity of conventional capacitors. Compared to lithium-ion batteries, they are able to accumulate and release the accumulated charge much faster, thereby providing high power.
As the experts explained, thanks to this, the supercapacitor can be used as a backup power source for such a battery, ensuring its stable operation at the time of peak loads. For example, at the moment of rapid climb by an unmanned aerial vehicle, a supercapacitor is able to smooth out the “drawdown” of voltage in the power supply system.
Currently, such devices are used as power sources in pre-start devices for the «cold» start of engines, pulse emitters and even electronic locks, as well as sources of main and additional power for electric vehicles. The ability to quickly charge supercapacitors makes it possible to effectively use them in energy recovery systems released during braking of electric vehicles.
Scientists from the Omsk State Technical University (OmSTU) reported that various carbon materials are traditionally used to manufacture supercapacitor electrodes. They have high electrical conductivity, but do not have the ability to accumulate a large charge.
Among these materials, a special type stands out — carbon nanotubes, whose high strength and flexibility make them attractive for the formation of new composites.
On the other hand, the researchers noted that the oxides of some transition metals (ruthenium, manganese, nickel, cobalt) can have a much higher specific capacity, but they are not used in their pure form as the electrode material of supercapacitors due to their high electrical resistance. Specialists from Omsk State Technical University suggested distributing metal oxides over the surface of carbon nanotubes, which would solve this problem and simultaneously increase the active surface area of the electrode material, and, consequently, increase the specific capacitance.
“In our work, we covered the surface of carbon nanotubes with continuous layers of oxide manganese. This made it possible to increase the amount of charge that the material is capable of storing by 3–4 times, depending on the magnitude of the discharge current,» said Sergey Nesov, associate professor of the Department of Physics at Omsk State Technical University.
According to him, further heat treatment of the composite material leads to the transformation of continuous layers of manganese oxide into nanoparticles no larger than 20 nanometers in size, which are firmly fixed on the surface of carbon nanotubes due to the formation of chemical bonds. The specific capacity of such a material increases almost fivefold compared to «pure» carbon nanotubes.
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Scientists believe that the results obtained in the work expand the base of experimental information about the structure and properties of nanomaterials, and the developed laboratory technologies for obtaining effective electrode materials for supercapacitors can be quickly scaled up to semi-industrial and industrial production.
Further research on This topic will be focused on the development of materials for the creation of efficient supercapacitors with high specific capacitance and stable characteristics. In addition, work is already underway to manufacture experimental samples of supercapacitors with electrodes based on the developed composite material.
Part of the research was carried out using technoparks of St. Petersburg State University, National Research Center «Kurchatov Institute» , as well as the equipment of the laboratory of technology of chemical current sources of the Omsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences.
OmSTU is a member of the state program to support universities «Priority-2030». The development is carried out within the framework of the strategic project of OmSTU «Ultra-wideband microwave microelectronics».