LiFe0.5Mn0.5PO4/C prepared using a novel colloidal route as a cathode material for lithium batteries

A new colloidal route for the preparation of LiFe0.5Mn0.5PO4/C nanocomposite cathode material for lithium batteries is revealed. The method uses lithium dihydrogen phosphate (LiH2PO4), ferrous chloride (FeCl2) and manganese chloride(MnCl2) in stoichiometric amounts with N-methylimidazole (NMI) as the solvent and carbon source. The coating process is performed at 650 °C for 3 h under vacuum. Elemental analysis shows a carbon content of 3.71 wt%, rendering the material to exhibit excellent electronic conductivity (9.29 × 10−2 S cm−1 at room temperature) and a significant increase in rate capability. Scanning electron and high-resolution transmission electron microscopy (SEM/HRTEM) images exhibited particles of uniform size (around 40-60 nm) that are covered by a 3-6 nm thick carbon layer. At a C/20 discharge rate and between 2.2 and 4.2 V vs. Li+/Li, the cell delivers a high capacity (140 mAh g−1) at the first cycle. The electrode stability was studied at C/10 rate, with only a small decrease (3.9%) of discharge capacity over 100 cycles, which suggests that the new synthesis method for carbon-coated LiFe0.5Mn0.5PO4/C material is very promising.