High Fuel Concentration Direct-Liquid Fuel Cell with a Redox Couple Cathode

Abstract

An approach to direct liquid fuel cells (DLFCs) has been investigated where the air cathode is replaced with a redox couple cathode. This different configuration, a direct liquid redox fuel cell (DLRFC), reduces the effect of fuel crossover, eliminates cathode flooding, allows the use of a carbon-based three-dimensional electrode for the cathode, and increases cell design flexibility. Furthermore, the use of a carbon-based cathode significantly reduces the fuel cell’s total platinum group metal content. Contrary to conventional DLFCs, high fuel concentrations can be employed in this type of configuration without depolarizing the cathode because the carbon-based cathode is selective to the redox couple only. Cyclic voltammetry (CV), differential scanning calorimetry (DSC), conductivity measurements, and fuel cell tests were used to characterize the system. CV and DSC have confirmed the electrochemical stability of methanol and the redox couple up to and in the potential window of vs a standard hydrogen electrode. DLRFCs at employing the redox couple at the cathode delivered peak power densities 5 and 3 times greater than DLFC equivalents (ambient pressure air) for acidic anolytes containing and HCOOH, respectively.