Nanoparticles enrichment to carbon felt electrodes for non-aqueous redox flow battery

Abstract

Non-aqueous electrolytes enable redox flow batteries to achieve higher energy density. However, commercially available, pristine carbon felt electrodes display high overpotentials for electrochemical reactions in a non-aqueous medium. It is then crucial to develop stable high-performance electrodes which display low activation overpotentials, low ohmic losses, and high porosity to ensure uniform flow-through distribution of the electrolyte. This study acknowledges the influence of using attached carbon-based nanoparticles to the fibers of the supporting carbon-felt electrodes. The use of reduced graphene oxide, graphene, multi-walled carbon nanotubes (CNT), carbon black Vulcan XC72, and Ketjen carbon nanoparticles bounded to the support carbon felt electrode using a Nafion ionomer was assessed. Post-mortem analysis revealed that the nanoparticles remained attached to the fibers even after intense charge-discharge cycling. The carbon felt containing CNT added to the fibers displayed the best performance on running the charge/discharge electrochemical reactions while achieving a 23 % higher energy efficiency compared to commonly used electrodes. The addition of noble metal-based nanoparticles Pt-rGO displayed only a slightly better performance of rGO. Good binding of the carbon nanoparticles was obtained by the addition of the ionomer in a ratio of 15 wt%.