Ascorbic acid-assisted solvothermal synthesis of LiMn_1-xFe_xPO₄/C nanoparticles for high-performance Li-ion cathode materials

LiFePO₄ is a promising cathode material for lithium-ion batteries due to its excellent rate capability and superior safety. However, its relatively low energy density makes the research efforts towards another olivine structure material LiMnPO₄, which exhibits higher energy density and operating voltage. Nevertheless, LiMnPO₄ does not show the remarkable electrochemical performance attributing from the low electronic/ionic conductivity. To solve the problems, a facile solvothermal method is used to successfully synthetise the LiMn_1-xFe_xPO₄/C with different Fe/Mn ratio (LMFP/C) nanoparticle in this paper. The length of the obtained LiMn_1-xFe_xPO₄/C is less than 200 nm. Owing to the doping of iron and the nano-structure, the LiMn_0.5Fe_0.5PO₄/C nanoparticle exhibits high discharge capacities of 153.6, 143.2 and 134.5 mAh g⁻¹ at rates 0.1 C, 1 C and 5 C, respectively. Furthermore, the effects of pH on the morphology evolution and electrochemical performance have been also investigated in detail.