Synthesis of nano FePO4 particles via high-temperature oxidative precipitation in microreactor

A novel high temperature oxidation precipitation method for synthesizing high-purity nano-sized ferric phosphate was proposed. We systematically investigated the impact of reaction temperature on the properties of the ferric phosphate product and its slurry. The study found that the FePO 4 obtained by the high-temperature precipitation method consisted of amorphous nanoparticles with a narrow size distribution around 30 nm. Increasing the reaction temperature did not affect the purity or crystal structure of the particles, but it reduced the viscosity and solid content of the slurry, beneficial for improving the solid-liquid separation efficiency in subsequent production processes. Characterization of products obtained at different reaction temperatures using FTIR, XPS, and ICP-OES revealed that elevated temperatures decreased the content of hydroxyl groups on the surface of the ferric phosphate particles, weakening the adsorption of metal ion impurities on the particle surface and the interaction between particles. The LiFePO 4 @C material synthesized using the nano FePO 4 product obtained by the high-temperature oxidative precipitation method as a precursor exhibited good rate performance (137.1 mAh g −1 at 5 C). This high-temperature oxidative precipitation method might enable controllable, continuous, and easily scalable production of nano-sized FePO 4 production.