In recent years ， fuel cell technologies attract much attention． It is also known that overpotentials in polymer electrolyte 血 el cells ( PEFCs ) are serious problems which decrease the energy conversion efficiency ． However ， effective solutions are required for the practical use ， In the present study ， we try to control proton flows and electric fields in membrane electrode assemblies ( MEAs ) to improve the current − voltage characteristics of PEFC ． The novel MEA ， on which addidonal silver electrodes are fabricated ， is prepared to invesdgate the effect of electric fields on proton flows through electrolyte membranes ． It is found that electric voltage losses can be suppressed by applying extemal voltages

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In fuel cell technologies, there are some problems which should be overcome rapidly. For example, it is known that voltage losses in polymer electrolyte fuel cells are serious problems. However, drastic solutions have not been found out yet. In the present study, we experimentally try to improve the energy conversion efficiency, focusing on ion currents in electrode membrane assemblies (MEAs). Additional Ag electrodes are fabricated on an MEA and their effects on proton flows are investigated. Consequently, it is found that electric voltage losses can be suppressed by electric or ion currents parallel to the proton flow. This result suggests that the external perturbations can be effective to protons and oxygen molecules on their reactions and on the power generation efficiency.

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