Hierarchical LFP/C (LiFePO4) nanoplate microspheres are prepared via a facile template-free route by self-assembling porous microspheres of the interconnected network nanoplate building blocks and are then further modified with carbon. The self-assembled hierarchical nanocomposites with open porous, flexible, and stable structures show improved rate capability and excellent cycle life and have potential application in advanced Li-ion batteries.