Electrochemical Study on MgO as an Additive in Molten Li2CO3-Na2CO3 for Molten Carbonate Fuel Cells

Abstract This study investigates the effect of MgO as an additive in molten Li2CO3-Na2CO3 electrolyte for molten carbonate fuel cells through electrochemical analyses. Addition of MgO (1~5 mol%) increased the electrochemical response in cyclic voltammogram of peroxide in molten Li2CO3-Na2CO3. The diffusion coefficient of peroxide in molten Li2CO3-Na2CO3 containing MgO was determined via the comparison between the peak currents of cyclic voltammograms from microwire electrode and macrowire electrode. The addition of MgO did not impact the diffusion coefficient, indicating that the increase in the electrochemical response with the addition of MgO might be attributed to the increase in the peroxide concentration. The change in peroxide concentration was also confirmed by electrochemical impedance analyses, which exhibited a decrease in the exchange current density. The increase in the concentration of peroxide with the addition of MgO might be associated with the high thermal decomposition constant of MgCO3, implying the high concentration of oxide ion in the molten Li2CO3-Na2CO3. This study suggests that MgO might be an effective additive for increasing the oxygen solubility in the molten Li2CO3-Na2CO3, and subsequently for enhancing the performance of molten carbonate fuel cells.

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Performance Study of Nickel Covered by Lithium Cobaltite Cathode for Molten Carbonate Fuel Cells: A Comparison in Li/K and Li/Na Carbonate Melts

Journal of Fuel Cell Science and Technology ◽

10.1115/1.3176402 ◽

2010 ◽

Vol 7 (2) ◽

Cited By ~ 2

Author(s):

C. Paoletti ◽

F. Zaza ◽

M. Carewska ◽

R. Lo Presti ◽

E. Simonetti

Keyword(s):

Fuel Cells ◽

Electrochemical Impedance ◽

Molten Carbonate ◽

Performance Study ◽

Nickel Substrate ◽

Surface Protection ◽

Before And After ◽

Lithium Cobaltite ◽

Molten Carbonate Fuel Cells ◽

Carbonate Melt

The slow dissolution of the lithiated NiO cathode represents one of the main causes of performance degradation in molten carbonate fuel cells. Two main approaches are usually investigated to overcome this problem: modifying the electrolyte composition and studying innovative cathode. In this work, the production of an alternative material as well as a study in different carbonate melt mixtures (62/38 mol % Li/K and 52/48 mol % Li/Na) of this innovative cathode have been taken into account. The issue of cathode surface protection was attained covering a nickel substrate with a thin layer of lithium cobaltite doped with magnesium (LiMg0.05Co0.95O2); a sol impregnation technique was used to deposit gel precursors on the porous surface of the substrate. Chemical analysis, electrical conductivity measurements and scanning electron microscopy were used to characterize the cathodes before and after in-cell tests. The cathodic performance was tested in two 3 cm2 area cells assembled with the following electrolyte compositions: Li/K=62/38 mol % and Li/Na=52/48 mol % in order to investigate the cathode behavior in different carbonate melt environments. Polarization curves and electrochemical impedance spectroscopy measurements were carried out during cell lifetime (about 850 h). Finally, different compositions of the cathodic gas were used to study the influence of oxygen and carbon dioxide on the electrode kinetics.

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Thermal energy recovery of molten carbonate fuel cells by thermally regenerative electrochemical cycles

Energy ◽

10.1016/j.energy.2021.120489 ◽

2021 ◽

pp. 120489

Author(s):

Armin Abdollahipour ◽

Hoseyn Sayyaadi

Keyword(s):

Fuel Cells ◽

Thermal Energy ◽

Energy Recovery ◽

Molten Carbonate ◽

Molten Carbonate Fuel Cells

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Lifetime expectancy of molten carbonate fuel cells: Part II. Cell life simulation using bench and coin-type cells

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2020.07.217 ◽

2020 ◽

Author(s):

Samuel Koomson ◽

Choong-Gon Lee

Keyword(s):

Fuel Cells ◽

Molten Carbonate ◽

Cell Life ◽

Molten Carbonate Fuel Cells ◽

Lifetime Expectancy

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Mechanical strength improvement of aluminum foam-reinforced matrix for molten carbonate fuel cells

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2017.03.096 ◽

2017 ◽

Vol 42 (25) ◽

pp. 16235-16243 ◽

Cited By ~ 6

Author(s):

Mihui Lee ◽

Chang-Whan Lee ◽

Hyung-Chul Ham ◽

Jonghee Han ◽

Sung Pil Yoon ◽

...

Keyword(s):

Fuel Cells ◽

Mechanical Strength ◽

Aluminum Foam ◽

Molten Carbonate ◽

Molten Carbonate Fuel Cells ◽

Strength Improvement

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Modeling of a Direct Carbon Fuel Cell System

Journal of Fuel Cell Science and Technology ◽

10.1115/1.4001015 ◽

2010 ◽

Vol 7 (5) ◽

Cited By ~ 7

Author(s):

K. Hemmes ◽

M. Houwing ◽

N. Woudstra

Keyword(s):

Fuel Cells ◽

Solid Oxide Fuel Cells ◽

Exergy Analysis ◽

Cell System ◽

System Model ◽

System Level ◽

Molten Carbonate ◽

Bench Scale ◽

Direct Carbon Fuel Cell ◽

Molten Carbonate Fuel Cells

Direct carbon fuel cells (DCFCs) have great thermodynamic advantages over other high temperature fuel cells such as molten carbonate fuel cells (MCFCs) and solid oxide fuel cells. They can have 100% fuel utilization, no Nernst loss (at the anode), and the CO2 produced at the anode is not mixed with other gases and is ready for re-use or sequestration. So far, only studies have been reported on cell development. In this paper, we study the performance of a CO2-producing DCFC system model. The theoretically predicted advantages that are confirmed on a bench scale are also confirmed on a system level, except for the production of pure CO2. Net system efficiencies of around 78% were found for the developed system. An exergy analysis of the system shows where the losses in the system occur. If the cathode of the DCFC must be operated as a standard MCFC cathode, the required CO2 at the cathode is the reason why a large part of the pure CO2 from the anode is recycled and mixed with the incoming air and cannot be used directly for sequestration. Bench scale studies should be performed to test the minimum amount of CO2 needed at the cathode. This might be lower than in a standard MCFC operation due to the pure CO2 at the anode side that enhances diffusion toward the cathode.

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