Self-sacrificed synthesis of three-dimensional Na3V2(PO4)3 nanofiber network for high-rate sodium ion full batteries

The morphological optimization of Na3V2(PO4)(3) (NVP) material has a great significance for improving the electrochemical performance since NVP suffers from intrinsic low electronic conductivity. For this purpose, a novel 3D NVP nanofiber network is controllably constructed via a facile self-sacrificed template method. Based on time-dependent experiments, an outside-in morphological evolution mechanism from microsphere to 3D nanofiber network is proposed. The as-synthesized material exhibits excellent cyclability (95.9% capacity retention over 1000 cycles at 10 C) and enhanced high-rate performance (94 mA h g(-1) at 100 C) for sodium half cell. Notably, when evaluated as full battery (NaTi2(PO4)(3) as anode) cathode, it also shows outstanding cycling stability (96.9% capacity retention over 300 cycles at 5 C) and superior rate capability (80 mA h g(-1) at 50 C). Such remarkable performance is attributed to the 3D nanofiber network structure, which provides multi-channel ionic diffusion pathway, continuous electronic conduction, and improved structural integrity. This self-sacrificed template strategy presented here can inspire new thought in constructing novel nanofiber/nanowire structures and accelerate the development of high-power sodium-ion batteries. (C) 2016 Elsevier Ltd. All rights reserved.