Characterization and electrochemical properties of high tap-density LiFePO4/C cathode materials by a combination of carbothermal reduction and molten salt methods

Olivine-structured LiFePO4 cathode materials were prepared via a combination of carbothermal reduction (CR) and molten salt (MS) methods. To enhance the powder's tap density, the LiFePO4/C composite was pressed into pellets and then sintered for at least 1 h at 1028 K in the reaction environment of KCl molten salts. The use of molten salt can effectively influence unit cell volume, morphology and tap density of particles, and consequently change the electrochemical performance of LiFePO4/C. The composites were characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy and tap density testing. The final product with high tap density of 1.50 g cm−3 contains 4.58 wt% carbon and exhibits good discharge capacity of 141 mAh g−1 at a 0.2 C-rate in the potential range of 2.8–4.0 V.