A simple analytical approach to simulate the electrochemical impedance response of flooded agglomerates in polymer fuel cells

2015 ◽  
Vol 157 ◽  
pp. 324-332 ◽  
Author(s):  
A. Baricci ◽  
A. Casalegno
Keyword(s):  
Fuel Cells ◽  
Analytical Approach ◽  
Electrochemical Impedance ◽  
Impedance Response

scholarly journals Effect of Stratification of Cathode Catalyst Layers on Durability of Proton Exchange Membrane Fuel Cells

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2975
Author(s):  
Zikhona Nondudule ◽  
Jessica Chamier ◽  
Mahabubur Chowdhury
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
Catalyst Layer ◽  
Cost Effective ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Potential Cycling ◽  
Catalyst Layers ◽  
Exchange Membrane

To decrease the cost of fuel cell manufacturing, the amount of platinum (Pt) in the catalyst layer needs to be reduced. In this study, ionomer gradient membrane electrode assemblies (MEAs) were designed to reduce Pt loading without sacrificing performance and lifetime. A two-layer stratification of the cathode was achieved with varying ratios of 28 wt. % ionomer in the inner layer, on the membrane, and 24 wt. % on the outer layer, coated onto the inner layer. To study the MEA performance, the electrochemical surface area (ECSA), polarization curves, and electrochemical impedance spectroscopy (EIS) responses were evaluated under 20, 60, and 100% relative humidity (RH). The stratified MEA Pt loading was reduced by 12% while maintaining commercial equivalent performance. The optimal two-layer design was achieved when the Pt loading ratio between the layers was 1:6 (inner:outer layer). This MEA showed the highest ECSA and performance at 0.65 V with reduced mass transport losses. The integrity of stratified MEAs with lower Pt loading was evaluated with potential cycling and proved more durable than the monolayer MEA equivalent. The higher ionomer loading adjacent to the membrane and the bi-layer interface of the stratified catalyst layer (CL) increased moisture in the cathode CL, decreasing the degradation rate. Using ionomer stratification to decrease the Pt loading in an MEA yielded a better performance compared to the monolayer MEA design. This study, therefore, contributes to the development of more durable, cost-effective MEAs for low-temperature proton exchange membrane fuel cells.

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

2021 ◽  
Author(s):  
Chan Mi Kim ◽  
In Ui Kim ◽  
S. P. Yoon ◽  
Sung Ki Cho
Keyword(s):  
Diffusion Coefficient ◽  
Fuel Cells ◽  
Electrochemical Impedance ◽  
Oxygen Solubility ◽  
Cyclic Voltammograms ◽  
Cyclic Voltammogram ◽  
Molten Carbonate ◽  
High Concentration ◽  
Electrochemical Response ◽  
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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