MOSCOW, December 9. Scientists at the St. Petersburg State Marine Technical University, as part of an international research group, have proposed a way to speed up the charging and discharging processes of sodium-ion batteries due to improved electrical conductivity and greater sodium capacity of the molybdenum selenide cathode; the results of the work are presented in Inorganic Chemistry.< br />According to the authors, the introduction of carbon atoms between the layers of cathode material will also increase the service life of batteries.
Lithium-ion batteries have recently attracted much attention due to their high energy/power density and long service life. At the same time, the high price and limited reserves of lithium in the earth’s crust hinder their further use, said specialists from St. Petersburg State Medical University. Since the number of devices with lithium-ion batteries is growing from year to year, and reserves of lithium-containing minerals are limited and localized only in some countries, experts predict a shortage of this type of charge storage by 2025.
An alternative to lithium-ion batteries is sodium-ion batteries, experts noted. With the same operating principle, when replacing metal, it is necessary to completely replace the materials of the electrodes in the batteries, which is due to the different radii of lithium and sodium ions. Since ions must be reversibly incorporated into the anode material during discharge and charging, the interlayer distance must be sufficient for the intercalation of sodium ions.
Despite the fact that sodium-ion batteries have begun to appear on the market, they are still at the development stage; work is now being carried out aimed at finding optimal design solutions, new materials and improving their production technology, experts explained. Additional difficulties with such charge storage devices arise due to the low rate of charging and discharging the battery, which is also associated with the large size of the sodium cation.
Scientists from St. Petersburg State Medical University, the Institute of Ion Plasma and Laser Technologies named after U. A. Arifov of the Academy of Sciences of the Republic of Uzbekistan and Hebei University of Technology (China) showed that the introduction of carbon atoms between Se-Mo-Se layers can accelerate the kinetics of charging-discharging processes due to increasing the distance between MoSe2 layers due to the improved electrical conductivity created by the carbon monolayers, while reducing volume change during the cycling process, which improves the stability of the energy storage device as the number of charge-discharge cycles increases.
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“The developed devices based on MoSe2/C anodes can achieve high energy density — approximately 1.5 times higher than analogues. Which is comparable to the performance of industrial lithium-ion batteries,” said one of the authors of the study, professor of the Department of Materials Science and Materials Technology of St. Petersburg State Medical University Oleg Tolochko.
According to him, the proposed type of two-dimensional MoSe2/C heterostructure has similar characteristics can be considered as an electrode with great potential for use in the anodes of high-performance sodium-ion batteries.
The work was supported by the Ministry of Science and Higher Education (project 0784-2020-0022).
SPbSMTU is a participant in the state support program universities of the Russian Federation «Priority-2030» of the national project «Science and Universities».
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