Synthesis of 3D “micro-nano-structure” LiFePO₄/C with high-rate capability and high tap density via a water bath process

The 3D “micro-nano-structure” LiFePO₄/C have been synthesized successfully from FePO₄·2H₂O precursor via a simple, inexpensive and continuously water bath process at 100 °C for 24 h by using Fe³⁺ as the iron source, followed by a rheological phase method. Both the properties of the FePO₄·2H₂O and the LiFePO₄/C were investigated by XRD and SEM. The results indicated that the 3D “micro-nano-structure” materials composited of nanoplates which are about 100 nm long and 50 nm thick, and had a hole in the center. Moreover, the FePO₄·2H₂O had a high yield above 85 %. Furthermore, the 3D “micro-nano-structure” LiFePO₄/C as cathode materials for Li-ion batteries were also evaluated. The materials showed excellent high-rate capability, with discharge capacities reaching 103 and 80 mAh g⁻¹ at high rates of 10 and 20 C, even could reach 40 mAh g⁻¹ when the current increased to 30 C. Moreover, the LiFePO₄/C had a high tap density about 1.5 g cm⁻³. As a result, the 3D “micro-nano-structure” LiFePO₄/C can be the cathode material for large-scale applications and industrialization.