A Hybrid Hydrazine Redox Flow Battery with a Reversible Electron Acceptor

Abstract

Hydrazine is a pollutant with high hydrogen content, offering tremendous possibilities in a direct hydrazine fuel cell (DHFC) as it can be converted into electricity via benign end products. Due to the inner sphere nature of the half-cell chemistries, hydrazine cross over triggers parasitic chemistry at the Pt based air cathode of the state of the art DHFC, overly complicating the already sluggish electrode kinetics at the positive electrode. Here we illustrate that by altering the interfacial chemistry of the catholyte from inner sphere to outer sphere, the parasitic chemistry can be dissociated from the redox chemistry of the electron acceptor and the fuel cell can be driven by simple carbon-based cathodes. The reversible nature of the outer sphere catholyte leads to a hybrid fuel cell redox flow battery with performance metrics ~4 times higher than Pt based DHFC-air configuration.