Effect of Sn-Doping on Behavior of Li-Intercalation in V2O5 Cathode Materials of Li-Ion Batteries: A Computational Perspective

We utilized first-principles plane-wave calculations to obtain insight into the role of Sn-doping on the behavior of Li intercalation in V2O5 cathode materials used in Li-ion batteries. Density functional theory (DFT+U) calculations were carried out to study microscopic structures and electronic structures of a Sn-doped V2O5 system. We find that the bonding interaction between Sn and the V2O5 lattice displays mixed ionic/covalent character in which Sn donates two of its four valence electrons to the nearby V centers and shares the other two valence electrons with the surrounding lattice. The extra electrons originated from Sn insertion increase the number of charge carriers which could improve electronic conductivity of the material. In addition, Sn insertion induces structural distortion in the V2O5 lattice which in turn affects thermodynamic and kinetic properties of Li intercalation. The calculated insertion energies and diffusion barriers describe how Li intercalates into the V2O5 structure in the presence of Sn. Although the inserted Sn atom may block and trap Li ion, most diffusion paths exhibit lower lying energy levels than those in the pure V2O5, suggesting that Sn-doping facilitates Li intercalation in V2O5-based cathode materials.