Li(MnxFe1−x)PO4/C (x = 0.5, 0.75 and 1) nanoplates for lithium storage application

Abstract

A simple solvothermal method was used to synthesize nanoplates of LiMnPO₄ (LMP) with a thickness of ∼60 to 80 nm. The LMP nanoplates were well characterized by PXRD, SEM and HRTEM techniques. The reaction conditions for the solvothermal method were found to be crucial to control the morphology of LMP. Carbon, silver, gold and copper have been coated on the surfaces of LMP nanoplates to improve the electronic conductivity. Despite such coating, the electrochemical activity of such metal-decorated LMP nanoplates was found to be minimal due to discontinuous wiring limiting the electronic conduction. Therefore, the Mn²⁺ in the nanoplates was partially substituted by the Fe²⁺ ion to obtain the following composition [LiMn_xFe_1−xPO₄ (x = 0.5 and 0.75)]. These solid solutions showed excellent storage performance compared to pure LMP. Especially LiMn_0.5Fe_0.5PO₄/C nanoplates exhibited a reversible capacity of 153, 121, 91 and 31 mA h g⁻¹ at 0.02, 0.1, 5 and 18 C respectively. In addition, LiMn_0.5Fe_0.5PO₄/C also demonstrated a stable long term cycling capacity of 103 mA h g⁻¹ at a 2 C rate up to 1000 cycles.