Porous LiMn0.6Fe0.4PO4 (LMFP) is synthesized by a modified sol–gel process. Highly conductive LMFP due to uniform dispersion of carbon throughout LMFP particles are achieved by the addition of sucrose as an additional carbon source. The LMFP obtained has a high specific surface area with a uniform, porous, and web-like nano-sized carbon layer on the surface. The initial discharge capacity and energy density of the LMFP cathode is 152 mAh g−1 and 570 Wh kg−1, respectively, at 0.1C current rate. The combined effect of high porosity and high electrical conductivity lead to fast lithium ion diffusion and enhance initial capacity compared to materials prepared by the general sol–gel method. However, with conventional electrolyte (1M LiPF6 in EC/DMC) poor cycle performance is observed due to HF attack. To improve the cycle stability we add tris (trimethylsily) phosphite (TMSP) as an additive in the electrolyte which dramatically improves cycle stability and rate-capability.