Polarization, solution-separator, charge transfer, and diffusion resistances of clean and used separator
electrode assemblies were examined in microbial fuel cells using current–voltage curves and electrochemical
impedance spectroscopy (EIS). Current–voltage curves showed the total resistance was reduced
at low cathode potentials. EIS results revealed that at a set cathode potential of 0.3V diffusion resistance
was predominant, and it substantially increased when adding separators. However, at a lower cathode
potential of 0.1V all resistances showed only slight differences with and without separators. Used separator
electrode assemblies with biofilms had increased charge transfer and diffusion resistances (0.1V)
when one separator was used; however, charge transfer resistance increased, and diffusion resistance did
not appreciably change with four separators. Adding a plastic mesh to compress the separators improved
maximum power densities. These results show the importance of pressing separators againstthe cathode,
and the adverse impacts of biofilm formation on electrochemical performance