Size-tunable tavorite LiFe(PO4)(OH) microspheres with a core–shell structure

Abstract

Core–shell structured tavorite LiFe(PO₄)(OH) microspheres were synthesized by means of a simple solvothermal route. These particles have a mesoporous structure consisting of a shell made up of submicro-sized particles and a core of nano-sized particles. The size of the particles can be tuned within a range of 0.7 μm to more than 7 μm, with no hollowing observed despite the longer reaction times needed to create a sufficiently high density for use as a precursor of LiFePO₄ in lithium-ion batteries. From the experimental data obtained, mechanisms for particle formation and crystal growth have been proposed based on the low dielectric constant of the reaction medium, the chemical potential difference induced by the adsorption of surfactants into the phosphate group, and the degree of supersaturation. In addition, the dependence of the electrochemical performance on the LiFe(PO₄)(OH) particle size is investigated.