Synthesis of hollow spherical LiFePO4 by a novel route using organic phosphate

Abstract

LiFePO₄ hollow spheres have been successfully synthesized by a one-pot hydrothermal process without any additional surfactant or template for the first time. The morphology of the product was greatly influenced by reaction conditions, such as pH, reaction time, precursor concentration, etc., and it was easily controlled from hollow spheres to solid spheres upon changing the precursor concentration. We found that LiOH increases the crystallinity of LiFePO₄ particles, and that the phosphate ester plays an important role in the construction of the self-assembled hollow spherical microstructures. The effects of the concentration of LiFePO₄ precursor solution and reaction time were also investigated. Based on the experimental results, the mechanism of crystal growth of LiFePO₄ is suggested where nanoparticles grow into big crystals in the thick shell and then are broken to small particles after a certain point. The hollow LiFePO₄ particles may be used as high-power cathode material, owing to fast kinetics of insertion and de-insertion of lithium ions at the surface of the shell.