Air-cathode structure optimization in separator-coupled microbial fuel cells.

Area of Science:

• Electrochemistry
• Renewable Energy Technologies

Background:

• Microbial fuel cells (MFCs) are devices converting organic matter into electricity using microorganisms.
• Optimized MFCs previously used 4 diffusion layers (DLs) in air cathodes to limit oxygen transfer.
• Newer MFC designs with separators require re-evaluation of cathode configurations for optimal performance.

Purpose of the Study:

• To investigate the impact of diffusion layer (DL) number and cathode wet-proofing on separator-coupled MFC performance.
• To determine optimal conditions for maximizing power density and coulombic efficiency in MFCs with separators.

Main Methods:

• Systematic variation of diffusion layers (DLs) and wet-proofing percentages on carbon cloth cathodes.
• Performance evaluation of microbial fuel cells (MFCs) under varying cathode configurations.
• Analysis of oxygen transfer, power density, and coulombic efficiency (CE).

Main Results:

• The number of DLs significantly affected MFC power density; 1 DL on a 50% wet-proofed cathode yielded 1427 mW/m².
• A 50% wet-proofed cathode with 1 DL outperformed a standard 30% wet-proofed cathode with 4 DLs by 31%.
• MFCs with 50% wet-proofing and 2 DLs achieved >84% CE at 6.8 A/m², exceeding previous results without separators.

Conclusions:

• Separator-coupled MFCs benefit from minimizing diffusion layers (DLs) to enhance oxygen transfer to the cathode.
• Optimal MFC performance is achieved with a balance between preventing water leakage and maximizing oxygen availability.
• Higher cathode wet-proofing percentages are beneficial for MFCs utilizing separators.