Tailoring Crystal Structure and Morphology of LiFePO₄/C Cathode Materials Synthesized by Heterogeneous Growth on Nanostructured LiFePO₄ Seed Crystals

Porous and coarse (5-10 μm) LiFePO₄/C composites with excellent electrochemical performance were synthesized by a growth technology using nanostructured (100-200 nm) LiFePO₄ as seed crystals for the 2nd crystallization process. The porous and coarse LiFePO₄/C presented a high initial discharge capacity (∼155 mA h g⁻¹ at 0.1 C), superior rate-capability (∼100 mA h g⁻¹ at 5 C, ∼65 % of the discharge capacity at 0.1 C), and excellent cycling performance (∼131 mA h g⁻¹, ∼98 % of its initial discharge capacity after 100 cycles at 1 C). The improvement in the rate-capability of the LiFePO₄/C was attributed to the high reaction area resulted from the pore tunnels formed inside LiFePO₄ particles and short Li-ion diffusion length. The improved cycling performance of the LiFePO₄/C resulted from the enhanced structural stability against Li-deficient LiFePO₄ phase formation after cycling by the expansion of the 1D Li-ion diffusion channel in the LiFePO₄ crystal structure.