Additive-Free Morphology Controlled Synthesis of Hierarchical Lithium Iron Phosphate Mesosturctures

Three dimensional hierarchical lithium iron phosphate mesostructures were successfully fabricated through a simple solvothermal synthesis by using the mixture of ethylene glycol/dimethylacetamide/water (EG/DMAC/H2O) as co-solvent. No other surfactant or template agent was applied. For the authors' best knowledge, it is the first application of EG/DMAC/H2O mixture as co-solvent for the synthesis of cathode materials as LiFePO4 for lithium ion batteries. Hierarchical LiFePO4 mesostructures with different morphology and size can be synthesized by adjusting the ratio of the EG/DMAC/H2O co-solvent. Palma-like, dumbbell-like and urchin-like hierarchical LiFePO4 mesostructures with different small-sized building blocks were finally obtained. The characteristics and electrochemical performance of the obtained three LiFePO4 mesostructures were investigated. It is found that the size of the whole structure and building blocks has a great affection on the electrochemical performance of the LiFePO4 mesostructures at low rate condition. Among the three LiFePO4 mesostructures, the urchin-like mesostructure composed of LiFePO4 nano-plates showed the best initial lithium intercalation property of 103 mAh g-1 at a current density of 17 mA g-1 (0.1 C) without any conductive coating, which should be attributed to the high specific surface area and high porosity introduced by the special superstructure and well crystallized LiFePO4 nano-plates composition units.