Identification and Comparison of Internal Resistances In a Proton-Exchange Membrane Fuel Cell and a Microbial Fuel Cell Using Electrochemical Impedance Spectroscopy
Doug S. Aaron1, Abhijeet Borole2, Choo Y. Hamilton3, Sotira Yiacoumi1, and Costas Tsouris2. (1) Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0373, (2) Oak Ridge National Laboratory, Oak Ridge, TN 37831, (3) University of Tennessee, Knoxville, Oak Ridge, TN 37831
Fuel cells are a rapidly developing field of energy conversion technology due to demonstrated high efficiency and low harmful waste products. Multiple tools exist to study and optimize various fuel cell designs; electrochemical impedance spectroscopy (EIS) is a useful tool to characterize internal resistances to transport in electrochemical systems. An EIS study of two fuel cell designs is presented here: proton-exchange membrane (PEMFC) and microbial (MFC) fuel cells. Charge transfer resistances at the anode and cathode electrodes and resistance to proton transport between the electrodes (termed PEM or solution resistance in the PEMFC and MFC, respectively) are of special interest. In addition, the capacitances existing between the electrodes and electrolyte are also studied. Experiments with the PEMFC involved changing the operating conditions and observing the effects on internal resistances and capacitance. MFC experiments involved optimizing the anode bacterial consortium and using different cathode configurations. In all experiments, the resistances in the MFC were much greater than in the PEMFC, usually by 1-2 orders of magnitude.