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标题：Graphene-Wrapped Anatase TiO2 Nanofibers as High-Rate and Long-Cycle-Life Anode Material for Sodium Ion Batteries
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作者：Yeolmae Yeo ; Ji-Won Jung ; Kyusung Park 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
期号：1
DOI：10.1038/srep13862
语种：English
出版社：Springer Nature
摘要：Anatase TiO₂ has been suggested as a potential sodium anode material, but the low electrical conductivity of TiO₂ often limits the rate capability, resulting in poor electrochemical properties. To address this limitation, we propose graphene-wrapped anatase TiO₂ nanofibers (rGO@TiO₂ NFs) through an effective wrapping of reduced graphene oxide (rGO) sheets on electrospun TiO₂ NFs. To provide strong electrostatic interaction between the graphene oxide (GO) sheets and the TiO₂ NFs, poly(allylamine hydrochloride) (PAH) was used to induce a positively charged TiO₂ surface by the immobilization of the -NH₃⁺ 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@TiO₂ 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 TiO₂ NFs. The improved electrochemical performances stem from highly conductive properties of the reduced GO which is effectively anchored to the TiO₂ NFs.