Abstract
In this research, lithium manganese phosphate nanoparticles of different morphologies were synthesized by solvothermal processes. Effects of manganese ions substituted by cobalt ions and magnesium ions were also investigated. The structure and morphology information were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The electrochemical properties of these materials were analyzed using cyclic voltammetry and cycling life test. The particle size and shape were affected by concentration of both reactants and surfactants. The needle-like shape particles were the narrowest ones, approximately 15 nm in width. At the charging and discharging rate of 0.1 C, non-doped lithium manganese phosphate nanoparticles had a discharge capacity of 73.8 mAh/g, while doped with 10% cobalt ions, the discharge capacity was improved to 121.1 mAh/g, and the capacity retention after 50 cycles was 42.1%. The effects of LiMnPO4 co-doped with Co2+ and Mg2+ were also investigated. The sample with 15% cobalt ions and 5% magnesium ions had the largest improvement in retention of 81.7% after 50 cycles, and the discharge capacity was 110.9 mAh/g.