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Exfoliation of Layered Na-Ion Anode Material Na2Ti3O7for Enhanced Capacity and Cyclability

Published version
Peer-reviewed

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Authors

Tsiamtsouri, MA 
Allan, PK 
Pell, AJ 
Stratford, JM 

Abstract

We report the exfoliation of layered Na2Ti3O7, a promising anode material for Na-ion batteries, and restacking using HNO3and NaOH to form H-[Ti3O7] and Na(x)-[Ti3O7] compositions, respectively. The materials were characterized by a range of techniques (SEM, TEM, solid-state NMR, XRD, PDF). Although the formation of aggregated nanoparticles is favored under acidic restacking conditions, the use of basic conditions can lead to control over the adherence between the exfoliated layers. Pair distribution function (PDF) analysis confirms that the local TiO6connectivity of the pristine material is maintained. The lowest sodium-containing phase Na(1)-[Ti3O7], which is the stable product upon Na+leaching after consecutive washing steps, displays the best performance among the compositions studied, affording a stable reversible capacity of about 200 mAh·g-1for 20 cycles at a C/20 rate. Washing removes the excess of "free/reactive" Na+, which otherwise forms inactive Na2CO3in the insufficiently washed compositions.

Description

Keywords

physics.chem-ph, physics.chem-ph

Journal Title

Chemistry of Materials

Conference Name

Journal ISSN

0897-4756
1520-5002

Volume Title

30

Publisher

ACS
Sponsorship
Engineering and Physical Sciences Research Council (EP/K01711X/1)
Engineering and Physical Sciences Research Council (EP/L019469/1)
Engineering and Physical Sciences Research Council (EP/K030132/1)
European Commission (604391)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (696656)
M.A.T, A.J.P, J.M.S, and R.N.K. acknowledge funding from the United States Department of Energy (DOE, funder reference: 7057154). P.K.A. acknowledges a Junior Research Fellowship from Gonville and Caius College and an Oppenheimer Fellowship from the University of Cambridge. European Union’s Horizon 2020 research and innovation programme under grant agreement No. 696656–GrapheneCore1 (G.K.)