Highly Stable Zero-Stain Na₂MoO₄/C Nanocomposite Anode for Long Life Na-Ion Batteries

The structure of the electrode material has been found to affect the electrochemical performance of rechargeable batteries. Thus, stable structured materials with large tunnels can provide long cycle life to help establish high-performance batteries. Herein, the electrochemical properties and associated reaction mechanism of a stable structured Na2MoO4 anode material are investigated in sodium-ion batteries. Na2MoO4/C nanocomposite is prepared using the ball-milling method and size of the particles is reduced from micro- to nanometers. The composite electrode shows high cycling stability exhibiting a specific capacity of 84 mAh g-1 at the first cycle and 81 mAh g-1 at the 1000th cycle, demonstrating a capacity retention of >96%. The reaction mechanism is evaluated with synchrotron-based in situ XRD and X-ray absorption spectroscopy. The results thus obtained, imply that the Na2MoO4/C anode shows low volume change (0.68%) in crystal structure upon cycling and Mo-O tetrahedral coordination is reversibly affected by the sodium insertion/extraction process.