Hierarchical, Porous Microspherical Lithium Iron Phosphate with Nanoparticle Shells for High-Rate Capacity and Stability Cathodes

Further promoting the application of lithium iron phosphate (LFP) requires both a high-rate performance and high volumetric energy density. Nanosizing and increased carbon content can improve rate performance but may decrease the volumetric energy density. Therefore, it is challenging to achieve both high volumetric energy density and excellent rate performance simultaneously for LFP. Here, we propose a heterogeneous spray-drying method to synthesize low-carbon-content hierarchical large microspheres filled with small microspheres composed of nanosized primary particles. The material was analyzed using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and in situ electrochemical impedance spectroscopy. The material exhibits a high tap density and excellent lithium-ion diffusion kinetics. Benefiting from the hierarchical large microsphere structure, the material maintains a capacity of 130.2 mA h g –1 at a rate of 10C and exhibits no capacity decay after 620 cycles at 1C. This study provides insights for the further promotion of LFP applications.