Electrochemical properties and reaction mechanism of ZnMoO4 nanotubes as anode materials for sodium-ion batteries

One-dimensional zinc molybdate (ZnMoO4) nanotubes with excellent sodium-storage performance are controllably and delicately prepared by a facile electrospinning method. The as-prepared nanotubes are systematically characterized. The charge-discharge cycling curves, cyclic voltammetry and rate performance further reveal the electrochemical properties of the samples when used as the new Sodium-ion batteries (SIBs) anode material. In the charge-discharge process, the initial discharge capacity of the electrode is 548 mAh g−1, and remains a reversible capacity of about 190 mAh g−1 after 500 cycles at the current density of 100 mA g−1. ZnMoO4 nanotubes also deliver an excellent rate capability. In addition, the sodium-storage reaction mechanism of ZnMoO4 nanotubes is revealed via ex-situ XRD and TEM analysis. The results suggest the transformation of ZnMoO4 to Zn and NaMoO4 at the potential of ∼1.0 V during the first discharge, which is subsequently converted to Zn and Mo nanograins of 3–5 nm with the deepening of the discharge. This study provides an in-depth understanding of the electrochemical mechanism of molybdates-type anode materials.