Applications of carbon-based nanomaterials as electrode catalysts for redox flow batteries (RFBs)

Several positive electrodes were employed in the hydrogen/manganese hybrid redox flow battery (regenerative fuel cell). This was a follow-on work from a similar investigation on a hydrogen/vanadium RFB. Graphite felt showed a better performance and thus this was used in combination with carbon metal fabrics (prepared by means of electrospinning) to improve the performance even further. High energy efficiencies more than 84% were noted at 100 mA cm−2 along with relatively high peak power densities around 0.6 W cm−2 (for gas-liquid based hybrid RFBs only). In addition, 100 charge/discharge cycles were successfully performed at the same current density with electrolyte capacities above 20 Wh L−1. Therefore, this combination of electrodes warrants further investigations in future to optimize the H/Mn system for potential commercial exploitation. It is worth noting that biomass-derived carbon electrodes can also be prepared via electrospinning, as discussed in our current work, and could be of exceptional value for RFBs in the future.