Department of Chemical and Materials Engineering, New Mexico State University , New Mexico 88003, United States.
College of Mechanical and Electrical Engineering, Agricultural University of Hebei , Baoding 071001, China.
ACS Appl Mater Interfaces. 2016 Aug 31;8(34):22213-9. doi: 10.1021/acsami.6b06516. Epub 2016 Aug 18.
Ultrafine niobium oxide nanocrystals/reduced graphene oxide (Nb2O5 NCs/rGO) was demonstrated as a promising anode material for sodium ion battery with high rate performance and high cycle durability. Nb2O5 NCs/rGO was synthesized by controllable hydrolysis of niobium ethoxide and followed by heat treatment at 450 °C in flowing forming gas. Transmission electron microscopy images showed that Nb2O5 NCs with average particle size of 3 nm were uniformly deposited on rGO sheets and voids among Nb2O5 NCs existed. The architecture of ultrafine Nb2O5 NCs anchored on a highly conductive rGO network can not only enhance charge transfer and buffer the volume change during sodiation/desodiation process but also provide more active surface area for sodium ion storage, resulting in superior rate and cycle performance. Ex situ XPS analysis revealed that the sodium ion storage mechanism in Nb2O5 could be accompanied by Nb(5+)/Nb(4+) redox reaction and the ultrafine Nb2O5 NCs provide more surface area to accomplish the redox reaction.
采用铌醇盐可控水解、在流动的还原气氛中 450°C 热处理的方法制备了超细氧化铌纳米晶/还原氧化石墨烯（Nb2O5 NCs/rGO）复合物，将其作为用于钠离子电池的一种很有前途的具有高倍率性能和高循环稳定性的正极材料。透射电子显微镜图像显示，平均粒径为 3nm 的 Nb2O5 NCs 均匀地沉积在 rGO 片层上，Nb2O5 NCs 之间存在空隙。超细 Nb2O5 NCs 锚定在高导电性 rGO 网络上的这种结构不仅可以增强电荷转移并在钠化/脱钠过程中缓冲体积变化，而且还可以为钠离子存储提供更多的活性表面积，从而实现优异的倍率性能和循环性能。原位 XPS 分析表明，Nb2O5 的钠离子存储机制可能伴随着 Nb(5+)/Nb(4+)氧化还原反应，而超细 Nb2O5 NCs 提供了更多的表面积来完成氧化还原反应。
