Mo 6+ Doping in Li 3 VO 4 Anode for Li-Ion Batteries: Significantly Improve the Reversible Capacity and Rate Performance.

Consider the almost insulator for pure Li3 VO4 with a band gap of 3.77 eV, to significantly improve the electrical conductivity, the novel Li3 V1-x Mox O4 (x = 0.00, 0.01, 0.02, 0.05, and 0.10) anode materials were prepared successfully by simple sol-gel method. Our calculations show that, by substitute Mo6+ for V5+ , the extra electron occupied the V 3p empty orbital and caused the Fermi level shift up into the conduction band, where the Mo-doped Li3 VO4 presents electrical conductor. The V/I curve measurements show that, by Mo doping in V site, the electronic conductivity of the Li3 VO4 was increased by 5 orders of magnitude. And thence the polarization was obviously reduced. EIS measurement results indicated that by Mo-doping a higher lithium diffusion coefficient can be obtained. The significantly increased electronic conductivity combined the higher lithium diffusion coefficient leads to an obvious improvement in reversible capacity and rate performance for the Mo-doped Li3 VO4 . The resulting Li3 V1-x Mox O4 (x = 0.01) material exhibited the excellent rate capability. At a high rate 5 C, a big discharge capacity of the initial discharge capacity 439 mAh/g can be obtained, which is higher than that of pure Li3 VO4 (only 166 mAh/g), and after 100 cycles the mean capacity fade is only 0.06% per cycle.