3D graphene-encapsulated Li3V2(PO4)3 microspheres as a high-performance cathode material for energy storage

Abstract

In this study, we report a promising structural design of the 3D graphene-encapsulated Li3V2(PO4)3 microspheres (3D-Li3V2(PO4)3/G) by using a facile spray-drying method with one-step calcination. XRD results indicate that the as-prepared composite shows a single monoclinic Li3V2(PO4)3 without any impurity phases. SEM and TEM images reveal that all the particles of 3D-Li3V2(PO4)3/G are spherical with diameters of about 5 μm and the surface of Li3V2(PO4)3 particles are tightly covered by soft graphene sheets, forming a conductive network. This unique structure of the composite offers a synergistic effect to facilitate the transport of electrons and Li+ ions. As the advanced cathode for lithium-ion batteries, the obtained 3D-Li3V2(PO4)3/G displays good high-rate capability and long cycling performance between 3.0 and 4.8 V (vs. Li/Li+). It delivers an initial specific capacity of 187 mAh g−1 at 0.1 C, which is close to the theoretical maximum value (197 mAh g−1). More remarkably, it presents a superior discharge capacity of 146 mAh g−1 at 20 C with capacity retention of about 95.7% over 100 cycles. Combined with the advantages of high voltage and high theoretical capacity, the 3D-Li3V2(PO4)3/G cathode material would be a potential cathode material for next-generation lithium-ion batteries.