Abstract
As a continuation of the investigation of Ni and lithiated NiO single‐crystal wettability by alternative electrolytes for molten carbonate fuel cells (MCFCs), the increment of contact angles has been studied when anodic or cathodic overpotential, respectively, was applied to these solids. This investigation was carried out at 650°C under hydrogen‐ or oxygen‐containing atmospheres, respectively, within the overpotential ranges corresponding to usual operating parameters of the MCFC stacks. Using contact angle values for NiO single crystals determined in the first part of this investigation, the optimal ratio of anodic to cathodic pore size values for porous MCFC electrodes has been calculated according to the Mugikura‐Selman relationship [Y. Mugikura and J. R. Selman, J. Electrochem. Soc., 143, 2442 (1996)]. When considering in these calculations the contact angle values for smooth, NiO single‐crystal surfaces, one should conclude that the equilibrium of capillary forces should be obtained at quite identical mean pore sizes in both porous electrodes. The electrode polarization should show only negligible effect on this equilibrium. © 2000 The Electrochemical Society. All rights reserved.