LiFePO4: From molten ingot to nanoparticles with high-rate performance in Li-ion batteries

LiFePO₄ (LFP) particles were obtained by grinding ingot synthesized in the molten state. This process, followed by jet milling, and then wet milling, provides a simple way to obtain powders with controlled particle size in the range from macroscopic to 25 nm. However, at this time, we find that these particles tend to agglomerate to form secondary particles of size ∼100 nm. The particles obtained by this process are characterized by X-ray diffraction (XRD). In situ and ex situ scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of milling was also investigated by analysis of physical properties using infrared spectroscopy (FTIR) and magnetic measurements. The electrochemical performance was evaluated in cells containing Li/1 M LiPF₆ in EC:DEC (1:1)/C-LiFePO₄. After carbon coating, the LFP particles which are free of impurities, exhibit high-rate capability. Even with a limited amount of carbon (2 wt.%) appropriate for commercial batteries, the capacity is 157 mAh g⁻¹ at 0.1 C, 120 mAh g⁻¹ at 10 C, without capacity fading after 60 cycles.