Carbon-coated LiMn0.4Fe0.6PO4 (LMFP) was synthesized by sol–gel technique using citric acid as foaming agent and carbon precursor. To evaluate the effect of synthetic conditions on the electrochemical properties of LMFP for use as cathode active material, the carbon-coated olivines were synthesized by a two-step thermal treatment at different temperatures. The composites were characterized by elemental analysis, XRD, SEM, TEM, Raman microprobe spectroscopy and their electrochemical properties were also studied. The composite that shows the better electrochemical performance has more porous structure, lower D/G band ratio in Raman spectra, and charge and discharge capacities of same 155mAhg−1 with higher material utilization of 97% at 0.1C-rate (0.05mAcm−2). The material exhibiting the better performance was also incorporated in a polymer electrolyte hosted in an electrospun P(VdF-HFP) membrane. The lithium polymer battery composed of LiMn0.4Fe0.6PO4 cathode and polymer electrolyte showed a good cycling performance with the initial discharge capacity of 146mAhg−1.