title: Improvement of Na Ion Electrode Activity of Metal Oxide via Composite Formation with Metal Sulfide.
abstract: The composite formation with a conductive metal sulfide domain can provide an effective methodology to improve the Na-ion electrode functionality of metal oxide. The heat treatment of TiO2(B) under CS2flow yields an intimately coupled TiO2(B)-TiS2nanocomposite with intervened TiS2domain, since the reaction between metal oxide and CS2leads to the formation of metal sulfide and CO2. The negligible change in lattice parameters and significant enhancement of visible light absorption upon the reaction with CS2underscore the formation of conductive metal sulfide domains. The resulting TiO2(B)-TiS2nanocomposites deliver greater discharge capacities with better rate characteristics for electrochemical sodiation-desodiation process than does the pristine TiO2(B). The23Na magic angle spinning nuclear magnetic resonance analysis clearly demonstrates that the electrode activities of the present nanocomposites rely on the capacitive storage of Na+ions, and the TiS2domains in TiO2(B)-TiS2nanocomposites play a role as mediators for Na+ions to and from TiO2(B) domains. According to the electrochemical impedance spectroscopy, the reaction with CS2leads to the significant enhancement of charge transfer kinetics, which is responsible for the accompanying improvement in electrode performance. The present study provides clear evidence for the usefulness in composite formation between the semiconducting metal oxide and metal sulfide in exploring new efficient NIB electrode materials.
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.
authors.forename: Seung Mi
authors.initials: SM
authors.lastname: Oh
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.
authors.forename: In Young
authors.initials: IY
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.
authors.forename: Sharad B
authors.initials: SB
authors.lastname: Patil
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.
authors.forename: Boyeon
authors.initials: B
authors.lastname: Park
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.
authors.forename: Jang Mee
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.
authors.forename: Kanyaporn
authors.initials: K
authors.lastname: Adpakpang
authors.affiliation: Western Seoul Center, Korea Basic Science Institute , Seoul 03759, Korea.
authors.forename: Seen Ae
authors.initials: SA
authors.lastname: Chae
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.|Western Seoul Center, Korea Basic Science Institute , Seoul 03759, Korea.|Graduate School of Analytical Science and Technology, Chungnam National University , Daejeon 34134, Korea.
authors.forename: Oc Hee
authors.initials: OH
authors.lastname: Han
authors.affiliation: Department of Chemistry and Nanoscience, College of Natural Sciences, Ewha Womans University , Seoul 03760, Korea.
authors.forename: Seong-Ju
authors.identifier: http://orcid.org/0000-0003-0233-1826
authors.initials: SJ
authors.lastname: Hwang
keywords: Na ion batteries; capacitive storage; composite formation; composite materials; metal sulfide