A boron phosphate-phosphoric acid composite membrane for medium temperature proton exchange membrane fuel cells

Fuel cell tests showed a significant enhancement in performance of BPOx over that of typical 5.6H3PO4-PBI membrane electrolyte. The enhancement is due to the improved ionic conductivity (3×), a higher exchange current density of the oxygen reduction (30×) and a lower membrane gas permeability (10×). Fuel cell current densities at 0.6 V were 706 and 425 mA cm−2 for BPOx and 5.6H3PO4-PBI, respectively, at 150 °C with O2 (atm).