Binder-free thin graphite fiber mat sandwich electrode architectures for energy-efficient vanadium redox flow batteries

Vanadium redox flow batteries (VRFB) are emerging as the preferred energy storage solution for long-duration energy storage (LDES) and grid-scale load levelling. In this study, we report a novel binder-free sandwich electrode architecture consisting of a thin layer (6–12 mg cm–2) of thermally activated graphite felt mat (TGFM) sandwiched between thin carbon papers (TCP-TGFM-TCP). This electrode architecture substantially reduced the polarization (I-V) resistance of the VRFB by 23 %, resulting in a current density increase from 340 mA cm–2 at 1 V for the thermally activated graphite felt (TGF) electrode to 470 mA cm–2 at 1 V, and an energy efficiency of 80 % at 100 mA cm–2 is realized.