关键词: 锂离子电池, 磷酸铁锂, 相变, 反应动力学, 晶格错配度

Abstract: Cathode materials LiFePO4 and LiFe0.9Mg0.1PO4 for lithium ion batteries were synthesized by a solid state reaction. Chemical oxidation to obtain Li0.4Fe0.9Mg0.1PO4 and Li0.1Fe0.9Mg0.1PO4 was carried out by reacting LiFe0.9Mg0.1PO4 with K2S2O8 solution of different concentration. Li0.1Fe0.9Mg0.1PO4 was confirmed to be a single phase compound with no impure phases,investigated by X-ray diffraction (XRD),selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM) techniques. Calculated lattice parameter results showed decreased lattice misfit between lithiated LiFe0.9Mg0.1PO4 and delithiated Li0.1Fe0.9Mg0.1PO4,compared lattice misfit between LiFePO4 and FePO4. It was considered the decreased lattice misfit as the structural basis for optimized high-rate capability of cathode material LiFe0.9Mg0.1PO4 for lithium ion batteries.

Key words: lithium ion battery, lithium iron phosphate, phase transformation, kinetic behavior, lattice misfit