High rate performance intensified by nanosized LiFePO₄ combined with three-dimensional graphene networks

A sample of nanosized LiFePO₄/graphene/carbon (NLFP/GC) hybrid material was achieved by homogenously dispersing a lab-fabricated NLFP (<100 nm) preparation inside well-exfoliated graphene, followed by carbon coating on the NLFP to constitute a three-dimensional network. For comparison, the NLFP coated with sucrose (NLFP/C) and the NLFP solely dispersed in graphene (NLFP/G) were prepared and evaluated. For these as-prepared products, the purity of the LFP component was characterized by X-ray diffraction, while the morphology was characterized by scanning electron microscopy and transmission electron microscopy. The nanosized and homogeneously dispersed NLFP/C in composite insures high capacities, indicating that can significantly shorten the pathway for lithium ion diffusion. Under different charge/discharge rates, the capacities of NLFP/GC are all higher than those of NLFP, NLFP/C, and NLFP/G. Also, NLFP/GC exhibited the excellent rate performance of 101 mAh g⁻¹ compared to NLFP/C (ca. 0 mAh g⁻¹) and NLFP/G (58 mAh g⁻¹) at 10C. It is clear that the three-dimensional graphene network of NLFP/GC, very efficiently promote the conductivity of the poorly conductive LiFePO₄. Also, the graphene skeleton can serve as a solid scaffold to restrain the aggregation of NLFP. The outstanding electrochemical performance of NLFP/GC derives from the nanosized NLFP in combination with the graphene/carbon layer.