Influence of Particle Size and Crystal Orientation on the Electrochemical Behavior of Carbon-Coated LiFePO4

We investigate the influence of particle size and crystal orientation on the electrochemical behavior of carbon-coated LiFePO4 prepared by a hydrothermal synthesis in the presence of a polymeric surfactant and a source of carbon. We evaluated the charge/discharge profiles of two samples, one constituted by particles in the micrometer range with a platelet-like shape (large ac facet and (020) crystal orientation) and another made of sub-micrometer-rounded particles with a random crystal orientation. At low current rates the crystal orientation seems to be the prevailing factor, whereas at high current rates smaller particles can allow a shorter electronic conduction path, so reducing the resistance experienced by Li ions during diffusion.