In this work we report the properties and electrochemical performance of composite electrodes containing lithium iron phosphate (LFP) and activated carbon (AC) as the active materials. These composite electrodes display high capacity during cycles carried out at specific current as high as 17.2Ag−1. Moreover, even after 500 cycles carried out at 8.6Ag−1, the electrodes display capacity retention higher than 98%. The high performance of these composite electrodes can be explained by a positive influence of AC on the LFP performance. The presence of AC increases the conductivity, reduces the density and modifies the porosity of the electrodes. The “dilution” of the LFP particles (with respect to the electrodes containing only LFP) results in exceptional high rate performance. During cycles carried out at specific current higher than 12Ag−1, LFP–AC electrodes display two times higher specific capacities compared to electrodes containing only LFP as active material.