Influence of Anode Pore-Size Distribution and Total Electrolyte Filling Degree on Molten Carbonate Fuel Cell Performance

Abstract

Experimental data of the total cell reaction resistance as a function of the total electrolyte filling degree was measured to investigate how more electrolyte initially may be added to get as long a cell lifetime as possible. The reaction resistance of each electrode was also measured using two gas compositions and various total electrolyte filling degrees. A theoretical model for the distribution of electrolyte between the anode and the cathode as a function of the total electrolyte filling degree was used to compare the experimental data in this study with data from a symmetrical cell setup. The model takes into account the electrode pore-size distributions and considers two cases for the contact angle between the electrode and the electrolyte for the anode: a zero wetting angle ͑fully wetted͒ or reported experimental values for the wetting angle on pure Ni. It was concluded that after the cathode initially has been sufficiently filled with electrolyte the anode pores have to be smaller than the remaining ones of the cathode to allow having the anode act as a reservoir to prolong cell lifetime. The results from the experimental data and the theoretical model for electrolyte distribution were compared with results from a symmetrical setup.

A review on MCFC matrix: State-of-the-art, degradation mechanisms and technological improvements

“…The optimal management is obtained when the electrolyte partially fills the electrode pores and completely fills the matrix ones. Generally, the electrolyte content within the matrix has to be maintained greater than 50 vol% [ 30 ], compared to a maximum of 30 vol% within the electrodes with usually a smaller value at the cathode showing an operation more sensitive to the electrolyte content [ 31 , 32 ]. Referring to the cell pore to filling ratio, defined as the electrolyte volume over the total pore volume, minimal polarization resistances have been reported at 50–80% with an exponential increase for lower and higher values [ 33 ].…”

Characterization of Spatial Distribution of Electrolyte in Molten Carbonate Fuel Cell Cathodes

“…The elevated operation temperature of MCFCs, that is, 650 °C, enables to keep the electrolyte (the mixture of Li/K or Li/Na carbonates) in a molten state, as well as to provide its sufficient ionic conductivity, and to provide sufficiently high catalytic activity or Ni‐based electrodes for promotion of electrochemical electrode reactions . The molten carbonates partly infiltrate the open‐porous cell components (cathode, anode, and matrix) due to wettability and capillary forces . In the light of the theory, it leads to formation of triple phase boundary (TPB) − region where electron conducting catalyst, ion conducting electrolyte, and pore space with reactant gases combine .…”