Phase Transformation and Diffusion Kinetics of V₂O₅ Electrode in Rechargeable Li and Mg Batteries: A First-Principle Study

Abstract

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.

Recent Progress on Layered Cathode Materials for Nonaqueous Rechargeable Magnesium Batteries

“…The phase transformation and migration energy barrier of V 2 O 5 were investigated by density functional theory. [38] With increasing Mg insertion content, the Figure 3a). The slow migration of Mg 2+ in -V 2 O 5 could be attributed to the strong interaction between Mg and the adjacent O atoms.…”

“…[89][90][91][92] Reproduced with permission. [38] Copyright 2018, American Chemical Society. b) Contour maps of in operando synchrotron diffraction of orthorhombic V 2 O 5 and the corresponding charge/discharge curves.…”

In Operando Synchrotron Diffraction and in Operando X-ray Absorption Spectroscopy Investigations of Orthorhombic V2O5 Nanowires as Cathode Materials for Mg-Ion Batteries

“…Li-ordering is discovered in Li-V2O5 system 32,59 , as well as has Li-ions at alternate locations along with a-axis 60 . Recently, Xiao et al 61 reported that V2O5 goes through a phase-transition of α-phase into ε-phase and then δ-phase in turn upon Mg insertion (0 → 0.5 → 1) using firstprinciples calculations. In the Li-V2O5 system, it is well known that a topotactic reaction is observed during lithium insertion into V2O5 (0 < x < 1) 62 , where "topotactic" is used to describe that the basic structure of the positive electrode material is maintained during the reaction.…”

3D porous V2O5 architectures for high-rate lithium storage

“…V 2 O 5 that outperforms most of the conventional cathodes (e.g., LiCoO 2 , LiFePO 4 , and LiNiO 2 ) satiates the increasing energy demands of LIBs [10][11][12] . Its exceptionally high specific capacity of 294 mAh g −1 (voltage window: 2.0-4.0 V) is endowed by the rich chemistry of V 2 O 5 to access plentiful redox reactions via the movement of ions along the layered structure of V 2 O 5 [13][14][15][16][17][18] . Although the thermodynamic expression signifies the available energy depends on the types of electrode materials, the theoretical value of chemical energy being stored in V 2 O 5 is difficult to be fully claimed due to the limitation in ion diffusion kinetics and electronic conductivity of V 2 O 5 .…”