Ordered-mesoporous Nb2O5/carbon composite as a sodium insertion material

Abstract

The present work introduces a new intercalation host for the Na ions, Nb2O5, and proposes that a mesoporous Nb2O5/carbon composite can function as a promising sodium insertion material. The highly ordered mesoporous Nb2O5/carbon electrode, synthesized using a block copolymer-assisted one-pot method, demonstrated not only a stable cycle life, but also outstanding rate capability. The excellent Na storage properties of the Nb2O5/carbon electrode were due to the uniquely ordered mesoporous nanostructure and in situ carbon formation whose configuration provided a large electrode-electrolyte interface area and enhanced Na ion and electron transport. Ex situ analyses revealed that Nb2O5 stores Na ions through Na de/intercalation reactions combined with surface capacitive reactions, after the activation process during the first sodiation. (C) 2015 Elsevier Ltd. All rights reserved.