Uniform 8LiFePO4·Li3V2(PO4)3/C nanoflakes for high-performance Li-ion batteries

Abstract

The synthesis of novel nanostructures at high temperatures is a big challenge because of the particle growth and aggregations. In particular, the fabrication of two active components with uniform structures is rarely reported. Herein, uniform 8LiFePO4·Li3V2(PO4)3/C nanoflakes have been synthesized by a one-pot, solid-state reaction in molten hydrocarbon, where the oleic acid functions as a surfactant. The composite components of LiFePO4 and Li3V2(PO4)3 are distributed homogenously within the nanoflakes. Moreover, the nanoflakes are coated by in-situ generated carbon from oleic acid during the sintering process in H2/Ar. The as-prepared 8LiFePO4·Li3V2(PO4)3/C nanoflakes are approximately 20–50nm in thickness and are stacked together to construct a porous structure, which have a surface area of 30.21m2g−1. The lithium ion diffusion coefficient can be greatly improved by making 8LiFePO4·Li3V2(PO4)3/C composite. As cathode material for lithium ion batteries, the as-prepared material exhibits excellent electrochemical performances, including high reversible capacity, good cyclic stability and rate capability. The composite electrode delivers a high capacity of 161.5mAh g−1 at 0.1C, which is very close to the theoretical capacity. Even at 10C, the electrode can deliver a specific discharge capacity of 118.6mAh g−1. After the long-term 1000 cycles, the electrodes can still retain 93.21% and 88.7% of its maximum specific discharge capacities at the rates of 2C and 5C, respectively. The results demonstrate the 8LiFePO4·Li3V2(PO4)3/C nanoflakes are promising cathode materials for high-performance lithium ion batteries.