Binary NiCoO2-modified graphite felt as an advanced positive electrode for vanadium redox flow batteries

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

25 Scopus Citations
View graph of relations

Related Research Unit(s)

Detail(s)

Original languageEnglish
Pages (from-to)5589-5600
Journal / PublicationJournal of Materials Chemistry A
Volume7
Issue number10
Online published4 Feb 2019
Publication statusPublished - 14 Mar 2019

Abstract

To address the challenges of the poor electrochemical performance of graphite felt electrodes in vanadium redox flow batteries (VRFBs), binary nickel cobalt oxide (NiCoO2 ) is developed as a novel candidate for the positive electrode via a facile hydrothermal and calcination approach. The graphite felt modified with NiCoO2 exhibits excellent electrochemical activity and reversibility in the VO2+ /VO2+ redox reactions resulting from the enhanced electrocatalytic activity of binary NiCoO2 , compared with pristine graphite felt and single metal oxide CoO-modified graphite felt. The flow cell employing a NiCoO2 -modified graphite felt electrode displays a voltage efficiency of 81.2% at a high current density of 150 mA cm-2 , which is higher than that of 66.9% and 77.5% obtained from pristine graphite felt and CoO-modified graphite felt electrodes, respectively. In particular, the discharge capacity of the flow cell is significantly enhanced, increasing from 185.4 mAh for graphite felt and 374.2 mAh for CoO-modified graphite felt to 469.4 mAh for NiCoO2 -modified graphite felt. No obvious efficiency decay is observed after 50 charge-discharge cycles confirming the stability of NiCoO2 deposition on graphite felt. Overall, the results demonstrate that the electrochemical performance of graphite felt can be further enhanced via introducing a binary metal oxide exhibiting higher conductivity and electrocatalytic activity compared with single metal oxides, providing guidelines for future research in VRFB studies.