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Highly Ordered Multi-layered Hydrogenated TiO2-II phase Nanowire Arrays Negative Electrode for 2.4 V Aqueous Asymmetric Supercapacitors with High Energy Density and Long Cycle Life

Abstract

To increase the active material loading coupling with the improvement of electric conductivity and ionic transport in the TiO2 based negative electrode for 2.4 V aqueous asymmetric supercapacitors (ASCs), a highly ordered binder-free multi-layered hydrogenated TiO2-II phase nanowire arrays (ML-HTO) electrode is synthesized via a multi-step method. Due to the highly ordered scaffold-like multi-layered structure, hydrogenated TiO2-II phase, small TiO2 grains (4.4 nm), high oxygen vacancy (Ti3+) concentration and functionalized hydrophilic surfaces, endowing the electrode high electric conductivity (low band gap of 2.39 eV), more positive flat-band potential (-0.35 V) and high Na+ diffusion coefficiency (3.08×10-8 cm2 s-1), the as-prepared ML-HTO electrode with high active materials loading (3.0 mg cm-2) exhibits a high areal specific capacitance (710.7 mF cm-2), which is much higher than that of the pristine TiO2 nanowire arrays (TO) electrode (28.3 mF cm-2) and the single layered hydrogenated TiO2 nanowire arrays (HTO) electrode (258.7 mF cm-2). Consequently, a 2.4 V aqueous ASC was firstly assembled with the ML-HTO electrode as the negative electrode, presenting a high energy density of 90.3 Wh kg-1 at 349.0 W kg-1, as well as a high volumetric energy density of 9.6 mWh cm-3 at 61.0 mW cm-3, which is much higher than most of previously reported aqueous ASCs. The capacitance retention of the as-prepared MnO2//ML-HTO ASC is 65.7 % after 10000 cycles, demonstrating its long cycle life.

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Publication details

The article was received on 31 Oct 2017, accepted on 04 Dec 2017 and first published on 04 Dec 2017


Article type: Paper
DOI: 10.1039/C7TA09590B
Citation: J. Mater. Chem. A, 2017, Accepted Manuscript
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    Highly Ordered Multi-layered Hydrogenated TiO2-II phase Nanowire Arrays Negative Electrode for 2.4 V Aqueous Asymmetric Supercapacitors with High Energy Density and Long Cycle Life

    Y. Tang, Y. Li, W. Guo, J. Wang, X. Li, S. Chen, S. Mu, Y. Zhao and F. Gao, J. Mater. Chem. A, 2017, Accepted Manuscript , DOI: 10.1039/C7TA09590B

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