A dual‐porosity, agglomerate‐type model for the porous anode and cathode of the molten carbonate fuel cell is developed and used to predict electrode performance in a small, differential‐conversion, cell. The model is based on a phenomenological treatment of mass transport, electrode kinetics, and ionic conduction, combined with structural assumptions. The model predicts the steady‐state performance, given a minimum number of structural parameters. Comparison with experimental data for a 3 cm2 anode and cathode shows good agreement for plausible values of these parameters.

AC impedance and current interruption measurements have been investigated as an in situ method for characterizing rate-limiting processes in molten carbonate fuel cell porous electrodes. Analysis of the data for the fuel cell anode indicates that the anode is always under strong mass-transfer control, in the temperature range of 600-700~ Analysis of data for the cathode indicates that at 650~ the cathode is under mixed control. Charge-transfer control is approached at lower temperature (600~ and at high CO2 partial pressures. Control by mass transfer or slow homogeneous reactions (e.g.,

The stationary polarization of small, differential conversion, molten carbonate fuel cells (3 cm 2) was measured between 600 and 700~ under various gas compositions. Multiple linear regression was used to correlate the experimental data and to infer the rate-limiting processes in fuel cell electrodes. The analysis indicates that both the anode and the cathode are primarily under mixed control at 700~ at low partial pressures of CO2. The anode does not exhibit charge-transfer control under normal operating conditions, due to its very fast kinetics. The superoxide mechanism appears to be the dominant reaction in a fuel cell cathode.

CO2 capture and sequestration (CCS) from stationary flue gas sources is one of the critical technologies needed as the future energy landscape shifts to low carbon intensity energy systems. Molten carbonate fuel cells (MCFCs) have the potential to capture CO2 from flue gas at higher thermal efficiency than traditional CCS technologies while simultaneously producing electricity. Herein, we present an investigation of molten carbonate fuel cell behavior at carbon capture conditions using simulated natural gas combined cycle flue gas. Measurements at these low CO2 and high current conditions reveal a lower than expected cathodic consumption of CO2 Based on the strong dependence of this deviation on water partial pressure as well as mass balances revealing a net consumption of water at the cathode, a parallel oxygen reduction mechanism is proposed. In this mechanism, water and oxygen are consumed at the cathode to produce hydroxide ions which migrate through the electrolyte to the anode. This parallel mechanism contributes to power generation but not to CO2 capture. Mass transport limitations in the molten carbonate fuel cell cathode were identified as the primary driver for this alternative mechanism which were heavily influenced by the design of the current collector and cathode interface.

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