Synthesis of LiNi_xFe_(1-x)PO_4 solid solution as cathode materials for lithium ion batteries

摘要

Nanosize LiNi_xFe_(1-x)PO_4 solid solution and LiNi_xFe_(1-x)PO_4/C nanocomposites were prepared via a solid state reaction method under argon atmosphere. A single phase olivine-type structure with Pnma space group was determined by X-ray diffraction. Crystallite sizes were found to be around 50 nm. A linear relationship was observed between lattice parameters and chemical composition which follows Vegard's law. Synthesized materials displayed electronic conductivity similar to previous reported values of LiFePO_4. Carbon coating further increased the overall conductivity of nanocomposites to the order of 10~(-3) S/cm. Chemical delithiation via NO_2BF_4 oxidant extracted more than 95% of lithium from the solid solution material accompanied by a decrease in lattice parameters.