Synthesis and characterization of multi-wall carbon nanotubes supported-hydrated iron phosphate cathode material for lithium-ion cells by a novel homogeneous precipitation method

摘要

Iron phosphate (FePO4) is a promising candidate for the cathode material in lithium-ion cells due to its easy synthesis and low cost. However, the intrinsic drawbacks of FePO4 material (i.e., the low electronic conductivity and the low lithium-ion diffusion coefficient) result in poor capacity. To overcome the shortcomings, multi-wall carbon nanotubes (MWNTs) supported hydrated iron phosphate nano-composites (FePO4·2H2O/MWNTs) are prepared using a novel homogeneous precipitation method. Meanwhile, the formation mechanism of highly dispersed and ultrafine FePO4·2H2O nanoparticles is discussed in detail. Electrochemical measurements show that FePO4·2H2O/MWNTs nanocomposites have a superior discharge capacity and stability. For example, FePO4·2H2O/MWNTs nanocomposites exhibit a high initial discharge capacity (129.9 mAhg~(-1)) and a stable capacity retention (114.3 mAhg~(-1) after 20 cycles). The excellent electrochemical performance is attributed to the small particle size of FePO4·2H2O nanoparticles, the good electronic conductivity of MWNTs, and the three-dimensional conductive network structure of FePO4·2H2O/ MWNTs nanocomposites.