In this study, we report the preparation and electrochemical evaluation of LiFePO 4 -carbon nanocomposites with carbon aerogels of varied pore size and distribution. In these composites, LiFePO 4 nanoparticles smaller than 50nm are confined to a three-dimensional (3D) microporous network that functions as the electronic and ionic conductor. The pore size of carbon aerogel is adjusted to achieve smaller LiFePO 4 nanoparticles. The KOH activation treatment of carbon aerogels is used to increase micropores that act as electrolyte reservoirs and is beneficial for ionic conductivity. Additional carbon coating of LiFePO 4 particles using glucose further enhances the electrode performance. The resultant composite electrodes exhibit superior rate performance and good cyclic stability due to the optimized nanostructure. The nanocomposites of LiFePO 4 and carbon areogels provide good examples of material nano-engineering owing to their tunable nanostructures.