title: Tunable Pseudocapacitance in 3D TiO2-δNanomembranes Enabling Superior Lithium Storage Performance.
abstract: Nanostructured TiO2of different polymorphs, mostly prepared by hydro/solvothermal methods, have been extensively studied for more than a decade as anode materials in lithium ion batteries. Enormous efforts have been devoted to improving the electrical conductivity and lithium ion diffusivity in chemically synthesized TiO2nanostructures. In this work we demonstrate that 3D Ti3+-self-doped TiO2(TiO2-δ) nanomembranes, which are prepared by physical vapor deposition combined with strain-released rolled-up technology, have a great potential to address several of the long-standing challenges associated with TiO2anodes. The intrinsic electrical conductivity of the TiO2layer can be significantly improved by the in situ generated Ti3+, and the amorphous, thin TiO2nanomembrane provides a shortened Li+diffusion pathway. The fabricated material shows a favorable electrochemical reaction mechanism for lithium storage. Further, post-treatments are employed to adjust the Ti3+concentration and crystallinity degree in TiO2nanomembranes, providing an opportunity to investigate the important influences of Ti3+self-doping and amorphous structures on the electrochemical processes. With these experiments, the pseudocapacitance contributions in TiO2nanomembranes with different crystallinity degree are quantified and verified by an in-depth kinetics analysis. Additionally, an ultrathin metallic Ti layer can be included, which further improves the lithium storage properties of the TiO2, giving rise to the state-of-the-art capacity (200 mAh g-1at 1 C), excellent rate capability (up to 50 C), and ultralong lifetime (for 5000 cycles at 10 C, with an extraordinary retention of 100%) of TiO2anodes.
authors.forename: Shaozhuan
authors.identifier: 0000-0002-4188-6421
authors.initials: S
authors.lastname: Huang
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Xueyi
authors.initials: X
authors.lastname: Lu
authors.affiliation: International Iberian Nanotechnology Laboratory (INL) , Avenida Mestre Jose Veiga, 4715-330, Braga, Portugal.
authors.forename: Lifeng
authors.identifier: 0000-0003-2732-7399
authors.initials: L
authors.lastname: Liu
authors.forename: Lixiang
authors.initials: L
authors.lastname: Liu
authors.forename: Xiaolei
authors.identifier: 0000-0001-6327-1527
authors.initials: X
authors.lastname: Sun
authors.forename: Yin
authors.initials: Y
authors.lastname: Yin
authors.forename: Steffen
authors.initials: S
authors.lastname: Oswald
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces , Potsdam 14424, Germany.
authors.forename: Zhaoyong
authors.initials: Z
authors.lastname: Zou
authors.forename: Fei
authors.initials: F
authors.lastname: Ding
authors.affiliation: Material Systems for Nanoelectronics, Technische Universität Chemnitz , Chemnitz, Germany.
authors.forename: Oliver G
authors.initials: OG
authors.lastname: Schmidt
keywords: 3D nanomembrane; Ti3+ self-doping; lithium ion battery; titanium dioxide; tunable pseudocapacitance