"Vanadium-doped LiFePO4/C
used as a cathode for a lithium ion battery has been successfully synthesized.
In this work, LiFePO4 was synthesized from LiOH, NH4H2PO4,
and FeSO4.7H2O at a stoichiometric amount. Vanadium was added in the
form of H4NO3V at concentration variations and 3 wt.%
carbon black. The characterization includes thermal analysis, X-ray
diffraction, electron microscopy, and electrical impedance spectroscopy. The
thermal analysis results showed that the LiFePO4 formation
temperature is 653.8?700.0°C. The X-ray
diffraction results showed an olivine structure with an orthorhombic space
group, whereas the electron microscopy results showed that LiFePO4/C
has a round shape with an agglomerated microstructure. Electrical impedance
test results showed values of 158 Ω and 59 Ω for the as-synthesized
LiFePO4/C and the 5 wt.% vanadium-doped
LiFePO4/C, respectively. Cyclic performance test results at 1 C
showed capacities of 24.0 mAh/g and 31.2 mAh/g for the as-synthesized LiFePO4/C
and the 5 wt.% vanadium-doped LiFePO4/C,
respectively. Charge and discharge test results showed charge and discharge
capacities of 27.6 mAh/g and 40.2 mAh/g for the as-synthesized LiFePO4/Candthe5 wt.%
vanadium-doped LiFePO4, respectively. This result is promising
in terms of increasing the performance of a lithium ion battery."
