High-purity LiFePO.sub.4 prepared by a rapid one-step microwave-assisted hydrothermal synthesis

A microwave-assisted hydrothermal synthesis route to prepare LiFePO.sub.4 (LFP) in a very short time and under a low temperature is proposed. Only 10 min at 200 °C was sufficient to produce a high-purity, single-phase LFP, with no need to perform a thermal treatment as a second step that is usual to enhance the structural properties of the material. The obtained LFP was structurally characterized by XRD, HR-TEM and FTIR spectroscopy and morphologically analyzed by SEM. Electrochemical impedance spectroscopy data allowed the estimation of the diffusion coefficient for the lithium ions (D.sub.Li.sup.+ = 2.0 x 10.sup.-14 cm.sup.2 s.sup.-1) in the LFP structure during the redox reactions related to the charge and discharge processes that occur in a Li-ion battery. Preliminary galvanostatic charge and discharge tests of the prepared LFP as a cathode in a Li-ion cell were carried out in a 1.0 mol L.sup.-1 LiPF.sub.6 EC/DMC 1:1 (V/V) electrolyte solution, allowing the estimation of the initial specific capacity (126 mA h g.sup.-1 at 0.1 C) and coulombic efficiency (94-99%). Hence, the here-reported rapid, clean and facile one-step synthesis of LFP allows the production of a material that has excellent structural properties and a promising electrochemical response, with significant savings in time and energy.