Synthesis and characterization of 0.95LiMn0.95Fe0.05PO4·0.05Li3V2(PO4)3 nanocomposite by sol-gel method

LiMn0.9Fe0.05V0.05PO4 (LMFVP) and nanocomposite 0.95LiMn0.95Fe0.05PO4·0.05Li3V2(PO4)3 (LMFP-LVP) are prepared by sol-gel and heat-treatment. The samples are characterized by X-ray diffraction patterns (XRD), scanning electron micrograph (SEM), and Bruauer-Emmett-Teller (BET) analysis. The coexistence of minor Li3V2(PO4)3 (LVP) in LiMn0.95Fe0.05PO4 (LMFP) plays the important role in electrochemical properties rather than V-doped in LMFP. LMFP-LVP nanocomposite delivers capacity of 176 mAh g−1 much higher than LMFVP of 115 mAh g−1. At 2C rate, LMFVP only delivers capacity of 47 mAh g−1 (no response at 5C rate). LMFP-LVP presents the improved rate performance of 126, 105 and 72 mAh g−1 at 1, 2 and 5 C-rate, respectively. Electrochemical impedance spectra (EIS) and galvanostatic intermittent titration technique (GITT) of LMFP-LVP confirm that the coexistence of minor LVP phase is positive to improve the lithium diffusion ability rather than V-doped in LMFP.