Electrode Reaction Characteristics under Pressurized Conditions in a Molten Carbonate Fuel Cell

Abstract

This work examines the overpotential behavior of two types of single cells with (cell I) and (cell II) anodes while under varying pressures up to . Inert gas step addition (ISA) and steady-state-polarization methods were employed. These methods revealed that cell I showed a lower anodic and cathodic overpotential ascribed to the gas-phase mass-transfer process compared to cell II. The results of the Hg porosimetry show that the anode has a more uniform pore structure with a smaller amount of small-size pores compared to the anode, which implies that the anode of cell II has a lower electrolyte content, resulting in a larger overpotential due to the increased diffusion resistance inside the pores. Both cells showed enlarged gas-phase-resistance induced overpotential at of pressure. Theoretically, reduced gas-phase diffusivity and flow velocity under pressurized conditions increase gas-phase mass-transfer resistance and its overpotential. However, pressurization reduces the overpotential of the liquid-phase mass-transfer resistance, which results in a total overvoltage decrease under pressurization.