Additional Carbon/Nafion Covering Layer on Electrode in Polymer Electrolyte Membrane Fuel Cell for Effective Operation at Low Relative Humidity Condition

Abstract

Demands for fuel cells that can operate in ambient conditions are increasing as their applications expand to portable devices and unmanned aircraft system. Particularly, maintaining high-hydration state of membrane electrode assembly (MEA) in the fuel cell in ambient condition is essential for prevention of performance degradation. At low relative humidity condition, the polymer electrolyte membrane exhibit poor ionic conductivity because the transfer of protons bonded with water molecules is severely limited. Therefore, developing the effective strategy to prevent dehydration in polymer electrolyte membrane fuel cell (PEMFC) is highly required. Herein, we successfully improve the MEA performance in low relative humidity condition by introducing a functional carbon-covering layer onto the catalyst layer on the cathode side. The carbon-covering layer plays an effective role to retain generated water and shows good compatibility with the MEA without interfering with the electrochemical reaction. Furthermore, we have investigated the optimized Nafion ionomer loading and the thickness of the carbon-covering layer for effective operation in both low and high relative humidity condition. Figure 1