Facile synthesis of LiMn0.75Fe0.25PO4/C nanocomposite cathode materials of lithium-ion batteries through microwave sintering

Abstract

LiMn0.75Fe0.25PO4/C nanocomposites are synthesized by a facile hydrothermal and ball-milling method, combining with spraydrying and microwave sintering process. X-ray diffractometer (XRD) and scanning electron microscopy (SEM) results reveal that the sintering process has a strong effect on the structures and morphologies of the as-prepared powders, and thus on the subsequent electrochemical performance. The lattice parameters (a, b, and c) of the microwave sintered sample are all smaller than those of the ordinary sintered sample. Meanwhile, compared to 299.66 Å3 of unit cell volume for the ordinary heating sintered sample, the value of the microwave sintered sample is 299.15 Å3. Transmission electron microscope (TEM) displays that the grains of the microwave sintered sample are less than 50 nm. The microwave sintered sample presents an excellent electrochemical performance with a discharge capacity of 143.5 mAh g-1 and capacity retention of 94.3% after 225 cycles at a rate of 0.1 C. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show that the microwave sintered electrode has a smaller charge-transfer resistance and a minor polarization and thus results in improved electrode kinetics. The microwave sintering is an economic, energy-saving, and time-saving synthetic method, which has great industrial application prospects.