V_(3)O_(7)·n H_(2)O纳米带高倍率储钠性能与机制研究

V_(3)O_(7)·n H_(2)O nanoribbons for high-rate sodium ion storage and investigations on their charge storage mechanisms

通过水热法成功制备出具有大层间距的层状钒基氧化物V_(3)O_(7)·n H_(2)O,其结构中层间H+与Na+间具有较弱的相互作用力,有利于载流子的快速固态传导。通过非原位X射线衍射与扫描电镜研究了V_(3)O_(7)·n H_(2)O的生长机理。将其应用于钠离子电池负极时,该材料展现出优异的电化学性能:在2 A/g的电流密度下循环1000次后放电比容量仍可达129 mAh/g,容量保持率为94%。同时,通过非原位表征发现,V_(3)O_(7)·n H_(2)O在循环中展现出的比容量上升现象与其结构相变有关。该研究结果为高倍率钒基储钠负极材料的研发提供了思路。

V_(3)O_(7)·n H_(2)O with a larger interlayer spacing was successfully prepared via a facile hydrothermal process.In the structure of V_(3)O_(7)·n H_(2)O,the interlayer H+cations interact weakly with Na+,which benefits the fast solid-state diffusion of the charge carriers.The formation mechanism of V_(3)O_(7)·n H_(2)O was carefully investigated by ex-situ XRD and SEM measurements.When applied as an anode material in sodium-ion batteries,V_(3)O_(7)·n H_(2)O delivers an outstanding electrochemical performance with a high specific capacity of 129 mAh/g and a capacity retention of 94%after 1000 cycles at a high rate of 2 A/g.Moreover,the phenomenon of capacity fluctuation was observed for V_(3)O_(7)·n H_(2)O during the cycling test,which was revealed to be associated with the structural evolution processes.The results may offer a reference for exploring high-rate vanadium-based sodium-ion battery anode materials.