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

• Na2MoO4 is firstly valuated as an anode material for lithium-ion batteries.
• Carbon-coated nanoplate α-Na2MoO4 sample is synthesized firstly via a facile sol–gel method.
• Residual carbon and reducing atmosphere would not change the valence of Mo (+6).
• Carbon-coated nanoplate α-Na2MoO4 presents outstanding rate abilities and cycle capabilities compared to the carbon-free sample.
• The Li storage mechanism of α-Na2MoO4 is conversion reaction confirmed by the ex-situ XRD and HRTEM results.

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 806 mAh g−1 and 409 mAh g−1 respectively in the first cycle, while a reversible discharge–charge capacity of 350 mAh g−1 can be retained after 30 cycles at 30 mAh g−1. A capacity of ∼320 mAh g−1 at 30 mAh g−1 can still recover after 50 cycles even following the discharge/charge process with the high current density of 480 mAh g−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.

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