Plate-like LiFePO4 crystallite with preferential growth of (010) lattice plane for high performance Li-ion batteries

Abstract

Plate-like LiFePO₄ nanocrystallites with preferential growth of the (010) lattice plane are successfully prepared by a low temperature synthesis using a binary mixed solvent system of water and ethylene glycol (EG). A series of analyses, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) were performed to characterize the structure and morphology of the as-obtained products. Compared with conventional LiFePO₄ nanoparticles, the LiFePO₄ nanoplates possess an enlarged (010) surface to volume ratio besides a reduced Li-ion transport length. Such preferential growth of the (010) lattice plane can strongly facilitate Li-diffusion and endow LiFePO₄ with an excellent high rate performance as a Li-ion battery (LIB) cathode material. The LiFePO₄ nanoplates exhibit a high Li-ion diffusion coefficient of 1.28 × 10⁻¹² cm² s⁻¹ compared to that of LiFePO₄ nanoparticles (i.e., 3.37 × 10⁻¹³ cm² s⁻¹). The as-obtained LiFePO₄ nanoplates deliver great capacities of 113.4 mA h g⁻¹ and 85.6 mA h g⁻¹ even at 10 C and 20 C respectively. In addition, micro-nano-structured morphology control provides an additional strategy to obtain excellent LiFePO₄ cathode materials with an excellent high rate performance and cycling stability.