Porous carbon-coated LiFePO4 nanocrystals prepared by in situ plasma-assisted pyrolysis as superior cathode materials for lithium ion batteries

The porous carbon-coated LiFePO 4 (LFP) nanocrystals synthesized by in situ plasma-assisted pyrolysis are reported. The particle size of LFP nanoparticles is well controlled through the coating of polyaniline (PANI) on FePO 4 . The effect of PANI content in FePO 4 /PANI on the morphology and electrochemical performance of LiFePO 4 particles is extensively investigated. Results show that the optimized amount of PANI in FePO 4 /PANI is 10.16% and the corresponding carbon content in activated porous carbon-coated LiFePO 4 (LFP/AC-P4) is 9.27%. The primary particle size of LFP/AC-P4 is 20~50 nm which are wrapped and connected homogeneously and loosely by activated porous carbon. The LFP/AC-P4 composite delivers a capacity of 166.9 mAh g −1 at 0.2 C, which is much higher than carbon-encapsulated LiFePO 4 nanocomposite (LFP/C) synthesized without the assistance of plasma pyrolysis (163.5 mAh g −1 ). Even at high rate of 5 C, a specific capacity of 128.4 mAh g −1 is achievable with no obvious capacity fading after 250 cycles.