Deciphering the exceptional kinetics of hierarchical nitrogen-doped carbon electrodes for highperformance vanadium redox flow batteries

Yang Li, Shida Yang, Yunhe Zhao, Nauman Mubarak, Mengyang Xu, Muhammad Ihsan-Ul-haq, Tianshou Zhao, Qing Chen, Jang Kyo Kim

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

High-performance vanadium redox flow batteries (VRFBs) necessitate robust carbon electrodes, whose rational design demands quantitative relationships between the electrode properties and performance. Here, we decipher the exceptional kinetics of VO2+/VO2+on a hierarchical nitrogen-doped carbon (HNC) electrode. Diffusion-less cyclic voltammetry, a method developed to evade the complex influence of diffusion in three-dimensional porosity, quantifies a rate constant of ∼5 × 10-7cm s-1on the electrode, substantially higher than that of un-doped porous carbons, in line with the calculated adsorption energies of solvated vanadium cations. The hierarchy is further linked to the high specific area via a comparison with graphite felt with and without carbon nanotube-decoration. The HNC electrode enables a VRFB of an exceptional energy efficiency of 76.8% over 2000 cycles at 400 mA cm-2, among the best reported. The work offers deep insights into the relationship of heteroatom doping, structural hierarchy, and kinetics for porous carbon electrodes for developing next-generation flow batteries.

Original languageBritish English
Pages (from-to)5605-5613
Number of pages9
JournalJournal of Materials Chemistry A
Volume10
Issue number10
DOIs
StatePublished - 8 Feb 2022

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