An economic and scalable approach to synthesize high power LiFePO4/C nanocomposites from nano-FePO4 precipitated from an impinging jet reactor

Abstract

A novel, economic and scalable method is proposed in this context using an impinging jet reactor to continuously precipitate FePO₄ (FP) nanoparticles with high purity. The LiFePO₄/C (LFP/C) nano-composites synthesized from the FP, lithium and carbon sources show fast charge capability and excellent power performance. The generated FP and LFP/C are characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and inductively coupled plasma (ICP) spectrometry. The LFP/C nano-composites are cycled at various C-rates to explore the electrochemical performance. When the pH of the working solution is 1.3, the molar ratio of Fe to P equals 1 in the obtained amorphous FP. In addition, the precipitation mechanism is discussed. Compared to the amorphous FP, the hexagonal FP obtained after calcining the former one is preferred to synthesize high power LFP/C. It is proved that 2 mol% excess LiOH is needed to compensate for the possible loss of Li during calcination. With 4.4 wt% of in situ carbon coating, the LFP/C nano-composites exhibit 145 mA h g⁻¹ at 10 C (1.7 A g⁻¹, 6 min) charge (without floating charge) and discharge, without obvious capacity loss up to 100 cycles, which is among the best high power performances reported so far. This strategy offers an inexpensive and easy control method to mass-produce high quality LFP/C nano-composites which might be suitable for powering hybrid electric vehicles and plug-in hybrid electric vehicles.