Abstract
Mono- (Li/Na), di- (Mg/Ca) and trivalent (Al) ion intercalation is investigated in the α and ζ phases of V2O5. Density functional theory is used to calculate the physical and electronic properties of each in the context of secondary battery cathodes. Various exchange-correlation functionals and van der Waals correction schemes are employed in calculating lattice parameters, bandgaps, density of states, cell voltages, and ion diffusion barriers. For intercalations of similar charge transfer (i.e., Li0.67, Na0.67, Mg0.33, Ca0.33, and Al0.20), Ca provides the highest voltage (2.95 V) in α-V2O5 with both PBE and PBE-D3. However, Li/Na yields the highest voltage (3.50 V/3.69 V) in ζ-V2O5 for PBE/PBE-D3. Monovalent ion diffusion barriers are calculated and show that Li and Na possess barriers of 0.39/0.32 eV and 1.27/1.09 eV in α/ζ-V2O5, respectively. A full voltage profile for Na intercalation in each phase determined the initial voltage in ζ-V2O5 (4.00 V) is higher than that in α-V2O5 (3.4 V), but lacks in specific capacity (168 mAhg−1 versus 235 mAhg−1). With a high diffusion barrier and low specific capacity, ζ-V2O5's utility as a sodium ion battery is bleak. However, both phases show promise for a lithium ion battery application.
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