六方多孔TT-Nb2O5微米片的固相制备与储锂性能

Synthesis of a novel hexagonal porous TT-Nb2O5 via solid state reaction for high-performance lithium ion battery anodes

本文通过固相反应首次合成了一种六方多孔Nb2O5材料。通过优化热处理温度调节Nb2O5材料的结构和电化学性能。XRD结果表明,在不同温度下可以合成伪六方晶系与正交晶系Nb2O5;SEM结果表明,所合成的Nb2O5材料具有正六边形貌与多孔结构。将该材料用作锂离子电池负极材料时,在600℃制备的伪六方结构Nb2O5(TT-Nb2O5)表现出最优的电化学性能。0.2C电流密度下,其可逆比容量为178 mA∙h/g;当电流密度提高到20C时,可逆比容量仍有86 mA∙h/g。优异的电化学性能得益于Nb2O5的赝电容式锂离子嵌入机制,通过晶体结构与比表面积调控显著提高Nb2O5的综合电化学性能。

Hexagonal porous Nb2O5 was synthesized for the first time via a facile solid-state reaction.The structure and electrochemical properties have been optimized through tuning heating temperature.X-ray diffraction results indicate that pseudo hexagonal Nb2O5(TT-Nb2O5)and orthorhombic Nb2O5 have been synthesized at different temperatures.Hexagonal sheet and porous structure of Nb2O5 were characterized by scanning electron microscopy and N2-adsorption-desorption isotherms.The as-prepared TT-Nb2O5(heated at 600℃)shows the best performance with a remarkable charge capacity of 178 mA∙h/g at 0.2C,which is higher than that of T-Nb2O5.Even at 20℃,TT-Nb2O5 offers unprecedented rate capability up to 86 mA∙h/g.The high rate capacity is due to pseudocapacitive Li+intercalation mechanism of TT-Nb2O5.The reported results demonstrate that Nb2O5 with good crystal structure and high specific surface area is a powerful composite design for high-rate and safe anode materials.