Facile and fast Na-ion intercalation employing amorphous black TiO^sub 2-x^/C composite nanofiber anodes

Structural and electronic modification of titanium oxide (TiO2) nanomaterials induced by the co-introduction of fully disordered glass phase and oxygen vacancies can lead to remarkable advances in the electrode performance in emerging energy storage systems. We report on the effective co-creation of...

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Published inElectrochimica acta Vol. 263; p. 417
Main Authors Lee, Na-Won, Jung, Ji-Won, Lee, Jun-Seo, Jang, Hye-Yeon, Kim, Il-Doo, Ryu, Won-Hee
Format Journal Article
LanguageEnglish
Published Oxford Elsevier BV 10.02.2018
Subjects
Anatase
Anodes
Batteries
Composite materials
Conductivity
Electrical resistivity
Electrodes
Energy storage
Heat treatment
Nanofibers
Nanomaterials
Rechargeable batteries
Sodium-ion batteries
Storage systems
System effectiveness
Titanium
Titanium dioxide
Titanium oxides
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Summary:Structural and electronic modification of titanium oxide (TiO2) nanomaterials induced by the co-introduction of fully disordered glass phase and oxygen vacancies can lead to remarkable advances in the electrode performance in emerging energy storage systems. We report on the effective co-creation of fully amorphous nanofibers (NFs) composed of black TiO2-x and conductive carbons throughout the NF structure, and evaluate the materials as potential anodes in sodium-ion batteries. The black TiO2-x nanofiber is successfully fabricated by electrospinning a precursor solution followed by a two-step sequential thermal treatment in an air and reducing atmosphere. The NF electrode could deliver approximately two-fold higher 2nd discharge capacity and an excellent kinetic performance even under high rates compared to that delivered by anatase-structured white TiO2 NFs used as reference, because of (i) an inherent free volume in the glass phase corresponding to the enlarged Na+ sites, (ii) increased electrical conductivity (low bandgap) resulting from the presence of Ti3+, (iii) introduction of conductive carbon agents around the TiO2-x domain, and (iv) one-dimensional NF feature allowing numerous Na+ reaction sites at the electrochemical interface. We also elucidate the morphological and structural changes in the nanofibers after discharge and charge by ex-situ characterizations.
ISSN:0013-4686
1873-3859