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

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 mm 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. (C) 2017 Elsevier B.V. All rights reserved.