A surfactant-assisted synthesis route for scalable preparation of high performance of LiFe_0.15Mn_0.85PO₄/C cathode using bimetallic precursor

A uniform carbon coated LiFe_0.15Mn_0.85PO₄ (LFMP/C) cathode material is synthesized by a surfactant-assisted, highly reproducible and energy-saving solid state method using a bimetallic oxalate (Fe_0.15Mn_0.85C₂O₄) precursor. The obtained LiFe_0.15Mn_0.85PO₄/C composite is characterized by X-ray diffraction (XRD), Raman spectrum, elemental analysis (EA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results demonstrate that the oleic acid as a surfactant, for the scale preparation of LFMP, plays a critical role in controlling size of the obtained composite. The LiFe_0.15Mn_0.85PO ₄/C exhibits high specific capacity and good rate performance. It delivers initial discharge capacities of 156.5, 142.5, 129.0 and 103.0 mAh g^-1 at 0.05, 0.1, 0.5 and 1C, respectively. Moreover, it shows good cycle stability at both room temperature (25 °C, 89% and 88% capacity retention after 250 and 500 cycles at 0.5 and 1C rates, respectively) and elevated temperature (55°C, 80% capacity retention after 200 cycles at 0.5C rate). The significantly improved rate and cycling capability of the LiFe _0.15Mn_0.85PO₄/C is attributed to the uniform carbon coating layer on the primary particles, the conductive network provided by the carbon between the LiMn_0.15Fe_0.85PO₄/C particles and the sufficient pores formed in the LiFe_0.15Mn _0.85PO₄/C aggregates. © 2014 Elsevier B.V. All rights reserved.