Enhancement of Quaternized Ammonium Polyaromatic Anion Membrane Performance in Alkaline Fuel Cells by Deposition of Graphene Oxide and Catalyst Ink Optimization*

To bolster the performance of polyaromatic ionomer membranes in alkaline fuel cells (AFCs), two major modifications were made. First, catalyst ink composition was optimized to yield the maximum power performance for the low platinum loading (0.6 mg/cm2). From the tested compositions, an 80:20 (catalyst: ionomer) ratio produced the greatest results for quaternary ammonium biphenyl membranes, yielding an improved 66 mW/cm2 power density despite reduced back-pressure.
In addition to determining an optimal ink composition, partially reduced graphene oxide (PRGO) was deposited onto catalyst-loaded electrodes. The membrane electrode assembly (MEA) reached a power density of 66 mW/cm2 at a low back-pressure of 50 kPa; likewise, the current density of 400 mA/cm2 was unprecedented for this particular polyaromatic membrane in prior tests. By varying the composition of the catalyst ink, we demonstrated a 453% increase in power per milligram platinum (PPMP) from 58% ionomer by mass to 20% ionomer by mass. Through the direct application of PRGO to the gas diffusion electrode surface, we achieved the highest recorded PPMP membrane — 0.97 W/mgPt in MEA 6.