A novel synthesis and characterization of LiFePO4 and LiFePO4/C as a cathode material for lithium-ion battery

• LiFePO4 is synthesized for the first time by a hydrothermal stripping route.
• Hydrothermal stripping is an effective, simple and green route to synthesize material.
• Coating carbon effectively improves the electrochemical performance of LiFePO4.
• LiFePO4/C has an excellent electrochemical performance for lithium ion batteries.

A novel hydrothermal stripping technique is developed to synthesize pure LiFePO4 and LiFePO4/C cathode materials. The pure sample is directly synthesized by the cation exchange between the organic phase which is prepared with FeSO4·7H2O and naphthenic acid, and aqueous phase prepared with H3PO4 and LiOH. SEM exhibits that the primary sizes of the well-distributed LiFePO4 and LiFePO4/C particles are about 150 nm and 100 nm in diameter, respectively. TEM indicates the LiFePO4/C is uniformly coated with a carbon layer about 2.7 nm in size. The as-prepared LiFePO4 exhibits a high initial discharge capacity of 135.5 mAh g−1 at 0.1 C, and the LiFePO4/C composite sintered at 650 °C for 4 h exhibits the best electrode properties with discharge capacities of 151.7, 154.8, 149.8 and 139.1 mAh g−1 at 0.1 C, 0.2 C, 0.5 C and 1.0 C rates, respectively. In addition, the LiFePO4/C also shows excellent capacity retention and cycle performances.