Graphene-Wrapped Anatase TiO2 Nanofibers as High-Rate and Long-Cycle-Life Anode Material for Sodium Ion Batteries

• Published in: Scientific reports Vol. 5; no. 1; p. 13862
• Main Authors: Yeo, Yeolmae, Jung, Ji-Won, Park, Kyusung, Kim, Il-Doo
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.09.2015; Nature Publishing Group
• Subjects: 639/301/299/161/891; 639/638/161/891; Batteries; Carbon; Electrical conductivity; Electrostatic properties; Graphene; Humanities and Social Sciences; Immobilization; multidisciplinary; Nanoparticles; Science; Sodium
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep13862

Anatase TiO 2 has been suggested as a potential sodium anode material, but the low electrical conductivity of TiO 2 often limits the rate capability, resulting in poor electrochemical properties. To address this limitation, we propose graphene-wrapped anatase TiO 2 nanofibers (rGO@TiO 2 NFs) through an effective wrapping of reduced graphene oxide (rGO) sheets on electrospun TiO 2 NFs. To provide strong electrostatic interaction between the graphene oxide (GO) sheets and the TiO 2 NFs, poly(allylamine hydrochloride) (PAH) was used to induce a positively charged TiO 2 surface by the immobilization of the -NH 3 + group and to promote bonding with the negatively charged carboxylic acid (-COO − ) and hydroxyl (-O − ) groups on the GO. A sodium anode electrode using rGO@TiO 2 NFs exhibited a significantly improved initial capacity of 217 mAh g −1 , high capacity retention (85% after 200 cycles at 0.2C) and a high average Coulombic efficiency (99.7% from the second cycle to the 200 th cycle), even at a 5C rate, compared to those of pristine TiO 2 NFs. The improved electrochemical performances stem from highly conductive properties of the reduced GO which is effectively anchored to the TiO 2 NFs.