title: Nb-doped rutile TiO₂: a potential anode material for Na-ion battery.
abstract: The electrochemical properties of the rutile-type TiO2 and Nb-doped TiO2 were investigated for the first time as Na-ion battery anodes. Ti(1-x)Nb(x)O2 thick-film electrodes without a binder and a conductive additive were prepared using a sol-gel method followed by a gas-deposition method. The TiO2 electrode showed reversible reactions of Na insertion/extraction accompanied by expansion/contraction of the TiO2 lattice. Among the Ti(1-x)Nb(x)O2 electrodes with x = 0-0.18, the Ti(0.94)Nb(0.06)O2 electrode exhibited the best cycling performance, with a reversible capacity of 160 mA h g(-1) at the 50th cycle. As the Li-ion battery anode, this electrode also attained an excellent rate capability, with a capacity of 120 mA h g(-1) even at the high current density of 16.75 A g(-1) (50C). The improvements in the performances are attributed to a 3 orders of magnitude higher electronic conductivity of Ti(0.94)Nb(0.06)O2 compared to that of TiO2. This offers the possibility of Nb-doped rutile TiO2 as a Na-ion battery anode as well as a Li-ion battery anode.
authors.affiliation: †Department of Chemistry and Biotechnology, Graduate School of Engineering, and Center for Research on Green Sustainable Chemistry, Tottori University, 4-101 Minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Usui
authors.affiliation: †Department of Chemistry and Biotechnology, Graduate School of Engineering, and Center for Research on Green Sustainable Chemistry, Tottori University, 4-101 Minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Yoshioka
authors.affiliation: †Department of Chemistry and Biotechnology, Graduate School of Engineering, and Center for Research on Green Sustainable Chemistry, Tottori University, 4-101 Minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Wasada
authors.affiliation: †Department of Chemistry and Biotechnology, Graduate School of Engineering, and Center for Research on Green Sustainable Chemistry, Tottori University, 4-101 Minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shimizu
authors.affiliation: †Department of Chemistry and Biotechnology, Graduate School of Engineering, and Center for Research on Green Sustainable Chemistry, Tottori University, 4-101 Minami, Koyama-cho, Tottori 680-8552, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sakaguchi
keywords: Li-ion battery; Na-ion battery; Nb doping; gas deposition; rutile-type titanium oxide; thick-film electrode