Mesoporous LiFePO4 microspheres for rechargeable lithium-ion batteries

A series of mesoporous LiFePO4/C microspheres have been successfully synthesized via a hydrothermal process using citric acid as chelating agent and reductant. The growth evolution process of the precursor is systematically investigated based on the time-dependent experiments. Pure mesoporous LiFePO4 microspheres are obtained with a diameter of ∼2 μm, which are composed of numerous compact nanoparticles (∼200 nm). These microspheric LiFePO4 shows high tap density (1.35 g cm−3) and large Brunauer–Emmett–Teller (BET) surface area (20.992 m2 g−1), which favor the electrochemical properties. The initial discharge capacity of LiFePO4/C microspheres is 163.8 mAh g−1 at 0.1 C rate, corresponding to 96.4% of the theoretical capacity of LiFePO4 (170 mAh g−1). The material also shows excellent high rate capability (120.3 mAh g−1, 10 C), and cycling stability (a capacity retention of 98.1% at 0.5 C rate after 200 cycles).

► LiFePO4/C microspheres were prepared by a template-free hydrothermal route.
► LiFePO4/C microspheres show superior electrochemical properties.
► The growth evolution process was systematically investigated.
► The lithium ion diffusion coefficients were studied.
► Cheap Fe3+ salt were used as iron sources.