This work studies the effect of doping with magnesium trisilicate for LiFePO4/C cathode materials by a solid-state
method. The samples were synthesized by two-step processing. Firstly, it was heated at 360 °C for 10 hours and then was
calcined at 700°C for 10 hours. All the annealing processing was carried out in argon atmosphere. The phase structure,
morphology and element distribution of prepared samples were characterized by XRD and scanning electron microscope
and energy dispersive spectrometer. The results show that Mg2+ and Si4+ co-doped LiFe0.99Mg0.01P0.985Si0.015O4/C cathode
materials exhibit higher capacity and rate capability than the unsubstituted LiFePO4/C cathode. For example,
LiFe0.99Mg0.01P0.985Si0.015O4/C exhibit discharge capacity of 146 mAh·g-1 compared to 140mAh·g-1 for unsubstituted
LiFePO4/C at 0.5C. Especially, at 5C rate, the discharge capacity of LiFe0.99Mg0.01P0.985Si0.015O4/C was remarkably
exceeded that of unsubstituted LiFePO4/C cathode materials. The better performances of the cathode were attributed to
the increase of electronic conductivity and the improved migration of lithium ion.
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