Synthesis of Carbon-coated Nanoplate α-Na2MoO4 and its Electrochemical Lithiation Process as Anode Material for Lithium-ion Batteries

Abstract

The carbon-coated α-Na2MoO4 nanoplate sample was fabricated via a facile sol–gel method involving the subsequent annealing under a reducing atmosphere to decompose the organic carbon source. X-ray diffraction with Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) results show that single-phase α-Na2MoO4 can be obtained even under the presence of carbon and reducing atmosphere. When evaluated as an anode material for lithium-ion batteries, the carbon-coated α-Na2MoO4 nanoplate electrode displays a discharge and recharge capacity of 806mAhg−1 and 409mAhg−1 respectively in the first cycle, while a reversible discharge–charge capacity of 350mAhg−1 can be retained after 30 cycles at 30mAhg−1. A capacity of ∼320mAhg−1 at 30mAhg−1 can still recover after 50 cycles even following the discharge/charge process with the high current density of 480mAhg−1. Meanwhile, carbon-free and carbon-coated α-Na2MoO4 powders fabricated via a solid state reaction were also prepared for comparison. Furthermore, the structure change of α-Na2MoO4 and its Li storage mechanism upon lithiation and delithiation process are studied by ex-situ XRD and TEM in below.