Mo-doped Li3V2(PO4)3/C cathode material with high rate capability and long term cyclic stability

Abstract Mo-doped Li 3 Mo x V 2− x (PO 4 ) 3 /C ( x  = 0, 0.01, 0.02, 0.03 and 0.04) are prepared through a fast sol–gel method. The X-ray diffractometer, scanning electron microscopy and high-resolution transmission electron microscopy are employed to characterize the prepared materials, and the evidences show that Mo element have been successfully incorporated into the Li 3 V 2 (PO 4 ) 3 lattice. The Li 3 Mo 0.03 V 1.97 (PO 4 ) 3 /C composite exhibits the most excellent electrochemical performance among all the samples. In the potential range of 3.0–4.3 V, Li 3 Mo 0.03 V 1.97 (PO 4 ) 3 /C exhibits the discharge capacities of 125.0 mAh g −1 and 122.8 mAh g −1 at 5 C and 10 C rates, respectively. A capacity of 117.6 mAh g −1 is still delivered at 20 C rate after 150 cycles with a capacity retention of 93.6%. In addition, the electrochemical impedance spectroscopy test proves that the electronic conductivity of Li 3 Mo 0.03 V 1.97 (PO 4 ) 3 /C is decreased, while the lithium ion conductivity is increased compared with the un-doped one. Based on above results, we conclude that the solid state diffusion of lithium ions is the rate-determining step of the extraction/insertion process.