Strategies for enhancing electrochemical activity of carbon-based electrodes for all-vanadium redox flow batteries

Two strategies for improving the electroactivity towards VO2+/VO2+ redox pair, the limiting process in all-vanadium redox flow batteries (VFBs), were presented. CuPt3 nanoparticles supported onto graphene substrate and nitrogen and oxygen polyacrylonitrile (PAN)-functionalized electrodes materials have been evaluated. The morphology, composition, electrochemical properties of all electrodes prepared was characterized with field emission-scanning electrode microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy and cell charge–discharge test. The presence of the CuPt3 nanocubes and nitrogen and oxygen functionalities enhance the electrocatalytic activity of the electrodes materials accelerating the oxygen and electron transfer processes. The battery performance was also evaluated using PAN-functionalized electrodes exhibiting a high of energy efficiency of 84% (at current density 20 mA cm−2) up to 30th cycle, indicating a promising alternative for improving the VFB.

► Improved reactions at the positive electrode in all-vanadium redox flow batteries.
► Graphene-derived and PAN-modified electrodes have been successfully prepared.
► Modification with bimetallic CuPt3 nanocubes yielded the best catalytic behavior.
► N and O-containing groups enhances the vanadium flow battery performance.