Hydrothermal growth kinetics and electrochemical properties of Li2FeSiO4 nanoparticles

Abstract

Li2FeSiO4 nanoparticles are successfully prepared using the hydrothermal method under different dynamic growth conditions. Structure and morphology of the samples are characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The nucleation activation energy in the initial nucleation process of Li2FeSiO4 nanoparticles is 49.1 kJ mol−1 based on the Arrhenius equation. The grain growth kinetics of Li2FeSiO4 is further discussed based on Lifshitz-Slyozov-Wagner (LSW) model with the equation D3 = (9.16 × 107) t exp(-41.3/T). Small activation energies of nucleation and growth confirm a low kinetic barrier for Li2FeSiO4 nanoparticle formation under hydrothermal conditions, as well as depicting nanoparticle growth as a diffusion-controlled process. Carbon coated Li2FeSiO4 samples, prepared at 210 °C with reaction times of 3 and 72 h, respectively, are used as cathode materials in half-cell batteries, and deliver initial discharge specific capacities of 152.4 and 145.2 mA h g−1 at 0.1 °C. Both samples display good cycle performance with a specific discharge capacity of 147.4 and 140.8 mA h g−1, respectively, after 50 cycles. The corresponding values of Li-ion diffusion coefficient of the samples obtained using electrochemical impedance spectroscopy are 1.50 × 10−13 and 5.76 × 10−14 cm2 s−1, respectively.