TWO-DIMENSIONAL FILMS BASED ON GRAPHENE / Li4Ti5O12 COMPOSITE AS A PROMISING MATERIAL FOR CHEMICAL CURRENT SOURCES
Vladislav V. Shunaev
Candidate of Sciences (Physics and Mathematics), Associate Professor,
Department of Radio Engineering and Electrodynamics,
Saratov State University
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Astrakhanskaya St, 83, 410012 Saratov, Russian Federation
Alexandr A. Petrunin
Postgraduate Student, Department of Radio Engineering and Electrodynamics,
Saratov State University
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Astrakhanskaya St, 83, 410012 Saratov, Russian Federation
Arseni V. Ushakov
Candidate of Sciences (Physics and Mathematics), Associate Professor,
Department of Physical Chemistry,
Saratov State University
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Astrakhanskaya St, 83, 410012 Saratov, Russian Federation
Olga E. Glukhova
Doctor of Sciences (Physics and Mathematics), Professor, Department of Radio Engineering and Electrodynamics,
Saratov State University
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Astrakhanskaya St, 83, 410012 Saratov, Russian Federation
Abstract. Based on the density functional theory method, supercells of graphene/ LTO composites with different mass ratios were obtained for the first time. Electron-energy properties were calculated for the obtained cells. It is found that the addition of graphene to the LTO unit cell closes the energy gap in the zone structure. The increase in the mass concentration of lithium titanate leads to an increase in the density of electronic states at the Fermi level and a decrease in the value of quantum capacitance at 0 volts. The analysis of the dependence of quantum capacitance on the applied voltage allows us to state that when using graphene/LTO composite as elements of HIT, the non-Faraday process prevails in the process of electrode discharge, and the Faraday process prevails in the process of charging. It is found by the elastic band method that the presence of graphene reduces the energy barrier of the lithium atom transition inside the LTO cell, which explains the experimental results. All calculations were performed within the framework of Density Functional Theory (DFT) in the SIESTA 4.1.5 software package. The exchange-correlation interaction was described within the Generalized Gradient Approximation (GGA) of the Perdew-Burke-Ernzerhof (PBE) functional using the Grimme correction to describe the van der Waals interaction.
Key words: graphene, lithium titanate, chemical current sources, density functional theory, elastic band method, quantum capacitance, density of electronic states, energy barrier.
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