  Vanadium oxides are among the most promising materials that can be used as
electrodes in rechargeable metal-ion batteries. In this work, we systematically
investigate thermodynamic, electronic and kinetic properties associated with
the insertion of Li, Mg and Al atoms in rutile VO2. Using first-principles
calculations, we systematically study the structural evolution and voltage
curves of LixVO2, MgxVO2 and AlxVO2 (0<x<1) compounds. The calculated lithium
intercalation voltage starts at 3.50 V for single-atom insertion and decreases
to 2.23 V for full lithiation, to the LiVO2 compound, which agrees well with
experimental results. The Mg insertion features a plateau about 1.6 V up to
Mg0.5VO2 and then another plateau-like region at around 0.5 V up to Mg1VO2. The
predicted voltage curve for Al insertion starts at 1.98 V, followed by two
plateaus at 1.48 V and 1.17 V. The diffusion barrier of Li, Mg and Al in the
tunnel structure of VO2 is 0.06, 0.33 and 0.50 eV, respectively. The
demonstrated excellent Li, Mg and Al mobility, high structural stability and
high specific capacity suggest a promising potential of rutile VO2 electrodes
especially for multivalent batteries.
