Issue 45, 2018

Engineering of a TiO2 anode toward a record high Initial coulombic efficiency enabling high-performance low-temperature Na-ion hybrid capacitors

Abstract

Initial coulombic efficiency (ICE) is an important evaluation index to weigh the applicability of electrode materials, but it is not acknowledged by many researchers. Herein, S-doped TiO2 nanosheets with porous and layered structures are utilized as anodes to fabricate hybrid sodium-ion capacitors in an ether electrolyte with high performance, especially through dramatically improved ICE. For Na-ion half cell tests in a DME electrolyte, S-doped TiO2 nanosheets display record high ICE of 88.6%, excellent rate capability and good cycling performance. We also find that TiO2 material with a large surface area is helpful for reducing the first irreversible capacity in an ether electrolyte, which is different from that observed using a traditional ester-based electrolyte. This could be due to excellent electronic conductivity with charge resistance of ∼1 Ω through the construction of an ultrathin solid electrolyte interphase (SEI) layer. Coupling with an Na3V2(PO4)3 cathode, we verify a successful Na-ion hybrid capacitor, delivering high energy and power density values of 158 W h kg−1 and 1075 W kg−1, respectively, at room temperature. Moreover, it also exhibits satisfactory performance of 82 W h kg−1 at −20 °C and outstanding cycling performance with over 95% retention after 800 cycles even at 1 A g−1 charge and discharge rate.

Graphical abstract: Engineering of a TiO2 anode toward a record high Initial coulombic efficiency enabling high-performance low-temperature Na-ion hybrid capacitors

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
24 Jul 2018
Accepted
19 Oct 2018
First published
20 Oct 2018

J. Mater. Chem. A, 2018,6, 22840-22850

Engineering of a TiO2 anode toward a record high Initial coulombic efficiency enabling high-performance low-temperature Na-ion hybrid capacitors

M. Kang, Y. Wu, X. Huang, K. Zhou, Z. Huang and Z. Hong, J. Mater. Chem. A, 2018, 6, 22840 DOI: 10.1039/C8TA07127F

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