High-Peak-Power Polymer Electrolyte Membrane Fuel Cells

A polymer electrolyte membrane fuel cell with amorphous hydrated ruthenium dioxide (RuO2 " xH2O) supercapacitative sublayers inserted between the electrocatalyst layers and the Nafion membrane was fabricated to enhance the cell’s pulse power output. RuO2 " xH2O material showed a high capacitance ~ca. 230 F/g! and allowed a much higher pulse power output, which was demonstrated by cyclic voltammetry and millisecond-width pulse voltammetry in a nitrogen atmosphere on both anode and cathode at 50°C. When the gases were changed to hydrogen and air, the sublayer slightly decreased the steady-state power output of the cell by decreasing both proton conductivity and the rate of oxygen reduction. In spite of this, the presence of the sublayer gave a much higher pulse power output, which is of value for, e.g., communications applications. This modified fuel cell performs the same functions as those of a more complex fuel cell/supercapacitor hybrid system without significant increase in weight, volume, and cost. Moreover, the blocking effect of the thin RuO2 on methanol crossover is advantageous for direct methanol fuel cell applications. © 2003 The Electrochemical Society. @DOI: 10.1149/1.1559068# All rights reserved.