First-Principles Calculations about Elastic and Li$^{+}$ Transport Properties of Lithium Superoxides under High Pressure and High Temperature
Yufeng Li1,2, Shichuan Sun1,2, Yu He1,2,3*, and Heping Li1,2
1Key Laboratory of High-Temperature and High-Pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China 2University of Chinese Academy of Sciences, Beijing 100049, China 3Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
Abstract：Lithium superoxides, Li$_{2}$O$_{3}$, LiO$_{2}$, and LiO$_{4}$, have been synthesized under high pressure. These materials have potential applications in energy storage devices. Here, we use first-principles calculations to investigate the elastic and Li$^{+}$ transport properties of these oxides at high pressure and high temperature. The elastic constants are calculated at 20–80 GPa, and they satisfy the Born stability criteria, indicating the good mechanical stability of these oxides. Their sound velocities calculated with elastic constants are close to each other, but difference in velocity anisotropy is obvious. LiO$_{2}$ presents significant shear sound wave anisotropy over 80%. The Li$^{+}$ transport properties are investigated using first principles molecular dynamics (FPMD) and climbing-image nudged elastic band methods. The lowest Li$^{+}$ migration barrier energies increase from 0.93, 0.86 and 1.22 eV at 20 GPa to 1.43, 1.12 and 1.77 eV at 50 GPa for Li$_{2}$O$_{3}$, LiO$_{2}$, and LiO$_{4}$, respectively. The most favorable path for LiO$_{2}$ and LiO$_{4}$ is along the [001] direction. The FPMD results suggest that these oxides become unstable with increasing temperature up to 2000 K due to O–O dimer clusters in these superoxides. Consequently, a superionic transition is not observed in the simulations.
. [J]. 中国物理快报, 2022, 39(2): 26101-.
Yufeng Li, Shichuan Sun, Yu He, and Heping Li. First-Principles Calculations about Elastic and Li$^{+}$ Transport Properties of Lithium Superoxides under High Pressure and High Temperature. Chin. Phys. Lett., 2022, 39(2): 26101-.
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