The impact of carbon nanofibers as conductive additive on the electrochemical performance of a LiFePO4-based composite electrode for lithium battery is investigated here. We use a new method that allows discriminating between the electronic and the ionic wirings contributions to the polarization and the specific capacity at different discharge rates [C. Fongy, et al., J. Electrochem. Soc., 157 (2010) A885; C. Fongy, et al., J. Electrochem. Soc., 157 (2010) A1347]. Results show this conductive additive is not only beneficial in terms of electronic wiring but it also enables to reach better high rate performance by improving the ionic wiring as it decreases the tortuosity of the porosity within the composite electrode architecture.