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Using the density functional theory (DFT), first-principles computations were performed to investigate the intercalation site, phase transformation, electronic properties, and migration energy barrier of Li and Mg atoms in V2O5 to thoroughly illuminate the phase transformation and microscopic interaction as well as the migration mechanism of Li and Mg in V2O5. It is found that Li and Mg atoms prefer to locate at the site that is above, near the center of the quadrilateral composed of four V atoms. With the increase of the intercalation concentration (0 ≤ x ≤ 1), V2O5 undergoes a structural transformation from α-phase to ε-phase and δ-phase. Compared with ε-M0.5V2O5 (M = Li/Mg), the electronic conductivity of δ-MV2O5 (M = Li/Mg) is declined. On the basis of diffusion kinetics, Mg exhibits more difficulty in inserting and extracting in V2O5 than Li. This study can be useful for the further application of V2O5 in Mg ion batteries.

Although magnesium rechargeable battery (MRB) raise considerable attention, the research on MRBs is still in its infancy. One of issues is that magnesium ions is difficult to reversibly (de)-intercalate in...

The thermodynamic, electronic, and kinetic properties were systematically investigated during the process of Li and Mg atoms into VOCl. The upper limit of Li and Mg intercalation into VOCl is xLi =1 and xMg=0.5, respectively. At high concentration, the further lithiation and magnesiation will cause the phase evolution. The pair correlation function (PCF) diagrams prove the formation of V metal at high concentration of xLi and xMg. The four discharge plateaus of lithiation are observed at 2.10, 2.23, 1.62 and 1.23 V vs. Li+/Li in the concentration range of 0≤xLi≤1, while the average voltage of the embedded Mg is 1.10 V vs. Mg2+/Mg in the concentration range of 0≤xMg≤0.25, which are consistent with the experimental values. The diffusion energy barriers of Li ions and Mg ions in VOCl are 0.22 and 0.72 eV, respectively, which are much lower than those of other intercalation materials. Based on the thermodynamic/kinetic properties and the AIMD simulation results, the electrochemical process of layered VOCl is an intercalation-conversion reaction process upon the lithiation and magnesiation processes.

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