An improved solid-state reaction route to Mg2+-doped LiFePO4/C cathode material for Li-ion battery

An improved solid-state reaction route has been employed to synthesize Mg2+-doped LiFePO4/C nanocomposite cathode by calcining the precursor obtained via evaporating the mixture of ascorbic acid, LiCH3COO·2H2O, Mg(CH3COO)2·4H2O, and amorphous FePO4 nanoparticles in anhydrous ethanol under continuous stirring. Ascorbic acid used here acted as both reducing agent and carbon source. The amorphous FePO4 was pre-prepared via a simple and fast oxidic precipitation method. Electrochemical tests showed that the final product exhibited good rate and cycling performance, with discharge capacities of 145.2 mAh g−1 at 0.2 C, 129.8 mAh g−1 at 1 C, 107.6mAh g−1 at 5 C, and 81.4 mAh g−1 at 20 C, respectively. The Mg2+-doped LiFePO4/C showed enhanced charge–discharge performance compared with undoped LiFePO4/C, especially at high rates. The enhanced electrochemical performance of the composite could be attributed to a combination result of the fine particle size with narrow particle size distribution, homogeneous carbon coating on the surface of the particles, and magnesium ion doping.