Corrigendum to Activating abnormal capacity in stoichiometric NaVO3 as cathode material for sodium-ion battery [J. Power Sources 400 (12 August 2018) 377–382]

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)Erratum

1 Scopus Citations
View graph of relations

Author(s)

Related Research Unit(s)

Detail(s)

Original languageEnglish
Article number228729
Journal / PublicationJournal of Power Sources
Volume477
Online published20 Aug 2020
Publication statusPublished - 30 Nov 2020

Abstract

The authors regret an incorrect interpretation of the XPS and XANES spectra in Fig. 3a and b of the original manuscript. The charge transfer mechanism during discharge was incorrectly attributed previously only to oxygen reaction as no peak shift of XPS is observed after charge and discharge. However, we found that the surface etching process performed before the XPS tests will change the valence state of vanadium [1], leading to erroneous conclusions on the charge-discharge mechanism. We therefore re-analyzed the XANES results to get more information about the discharge mechanism and estimate the contribution of capacity from vanadium redox reactions. 
The experimental XANES data were first normalized using the first inflection point of the EXAFS oscillations, as indicated by Chaurand et al. [2]. The edge position is defined as the energy corresponding to the normalized absorption of 0.5. The XANES profiles of NaVO3 at different state of charge together with V2O5 and VO2 references are shown in Fig. C1 and the corresponding edge energies are listed in Table 1. One can see that there is no change in oxidation state of V in NaxVO3 during charging to 4.9 V, indicating that V does not participate in charge transfer during charging. In contrast, after discharging to 1.5 V, the edge position shifts left by 0.63 eV, indicating that vanadium is reduced during sodium insertion. Compare to the change of 1.51 eV for V5+/4+ reaction based on V2O5/VO2 standard references, a shift of 0.63 eV suggests the average valence of our NaxVO3 material changes from 5+ to 4.58+ during discharge. This corresponds to a capacity of about 91.8 mAh g−1 from vanadium redox reaction. Since the observed first discharge capacity is 112.3 mAh g−1, the difference of 20.5 mAh g−1 is attributed to reversible oxygen reaction, as XPS spectra of O1s in Fig. 3c show a decrease of (O2)n− peak with an increase of O2- peak after discharging to 1.5 V. Overall, both vanadium redox reaction and oxygen redox reaction contribute to the discharge capacity of NaVO3 cathode. The authors would like to apologize for any inconvenience caused.

Citation Format(s)